JP4395257B2 - Catalyst film, method for preparing catalyst film, and electrical synthesis of compound using catalyst film - Google Patents

Description

[0001]
(Technical field)
The present invention relates to methods for preparing hydroxylammonium salts and hydroxylamines using mediators, catalyst films, methods of making catalyst films, and methods of using catalyst films. More particularly, the present invention relates to a catalyst film formed on an electrode by the interaction of a film-forming compound and nitrate ions.
[0002]
(Background of the Invention)
Hydroxyl ammonium salts are compounds with various applications. For example, hydroxylammonium nitrate can be used as a component of liquid fuels and as a reducing agent in photographic operations. In some of these applications, it is desirable that a high purity hydroxylammonium salt solution be available.
[0003]
There are several production methods for producing hydroxylammonium salts. For example, in the case of hydroxylammonium nitrate, some of these methods include: electrodialysis of hydroxylammonium chloride and nitrate; reaction of hydroxylammonium sulfate and barium nitrate; using hydroxylammonium sulfate and nitric acid 3 Process cation exchange process; and electrolytic reduction of nitric acid. However, some of these methods do not provide the high purity hydroxylammonium salt solution required by some applications of this compound. As a result, procedures have been developed to purify hydroxylammonium salt solutions produced by existing methods. Nevertheless, there is still substantial demand for large quantities of high purity hydroxylammonium salt solutions. There is also a need for an efficient process for making hydroxylammonium salts.
[0004]
Hydroxylamine is useful as an intermediate in chemical processes, particularly in the pharmaceutical industry and agriculture. This is also useful in stripper formulations. The stripper formulation can be used to remove the photoresist from the substrate or to clean the substrate. For example, a hydroxylamine stripper solution can be used to remove a polyamide coating from a metal foil. Hydroxylamine stripper solutions are utilized in the printed circuit board and semiconductor industries.
[0005]
Frequently, solutions of hydroxylamine, especially those prepared from hydroxylammonium salts, contain undesirable amounts of impurities such as salts, ammonium ions, metals and organics. There is therefore a need for a hydroxylamine solution having a high purity. There is also a need for an efficient process for making hydroxylamine.
[0006]
The production of hydroxylamine by electroreduction of nitric oxide in sulfuric acid is J. et al. J. Janssen et al., Electrochimica Acta, 1977, Vol. 22, p. L. Bathia et al., The Canadian Journal of Chemical Engineering, Vol. 57, October 1979, pages 631-7. Janssen et al. Utilize a platinum cathode, and Bathia et al. Utilize a cathode bed of tungsten carbide particles. The electroreduction of nitric oxide with large amounts of platinum in perchloric acid and sulfuric acid solutions is described in J. Am. A. Colucci et al., Electrochimica Acta, Vol. 30, No. 4, 521-528, 1985.
[0007]
US Pat. No. 5,281,331 relates to a process in an electrolysis cell including: (A) an anolyte compartment with an anode, a catholyte compartment with an oxygen-consuming cathode, and an anolyte compartment and Providing an electrolysis cell comprising an anionic partition separating the catholyte compartment; (B) an aqueous solution containing acid and water in the anolyte compartment, and a hydroxylamine salt, water, in the catholyte compartment; And, optionally, providing an aqueous solution containing an acid; (C) filling the catholyte compartment with an oxygen-containing gas; (D) reducing the acid content in the catholyte compartment and / or salting hydroxyl Passing direct current through the electrolysis cell for a period of time effective to convert to amine; and (E) catholyte compartment From the chamber, recovering the hydroxylamine or hydroxylamine salt solution containing acid reduced amount.
[0008]
US Pat. No. 5,447,610 describes neutral electrolytes to form at least one dinitrogen monoxide and hydroxylamine, or acidic electrolytes such as organic or inorganic acids to form hydroxylammonium salts. It relates to the preparation of hydroxylamine and hydroxylammonium salts by electrolytically reducing a mixture containing either. The electrolytic reduction is performed in an electrolysis cell comprising an anolyte compartment with an anode, a catholyte compartment with a cathode, and a partition that separates the anolyte compartment and the catholyte compartment. Here, at least one nitrous oxide and electrolyte mixture is present in the catholyte compartment and acid is present in the anolyte compartment.
[0009]
(Summary of the Invention)
In one embodiment, the present invention relates to a catalyst film made by applying an electric current to an electrochemical cell comprising two electrodes and a solution comprising a film-forming compound and a nitrate ion source.
[0010]
In another embodiment, the present invention relates to a method of making a catalyst film comprising applying an electric current to an electrochemical cell comprising: an anode, a cathode, and a solution comprising a film-forming compound and a nitrate ion source. And thereby forming a catalyst film.
[0011]
In another embodiment, the present invention is made by applying a current to a first electrochemical cell comprising an anode and a cathode and a film forming solution comprising a film forming compound and a nitrate ion source. Concerning a method of using a catalyst film formed on the cathode, the method comprises: providing a second electrochemical cell comprising an anode, a cathode having the catalyst film, and a reactant solution comprising a reactant. Applying a current to the second electrochemical cell; and recovering a product from the second electrochemical cell.
[0012]
In another embodiment, the present invention relates to a method of preparing a hydroxylammonium salt, the method comprising: an anode, a cathode, and a divider located between the anode and the cathode, the cathode and the partition. Providing an electrochemical cell with a partition plate defining a catholyte compartment between the plate and an anolyte compartment between the anode and the partition; the catholyte compartment containing nitrogen Filling the anolyte compartment with a first solution comprising a compound and a mediator and a second solution comprising an ionic compound; passing an electric current through the electrochemical cell and the catholyte compartment Producing a hydroxylammonium salt in the chamber; and recovering the hydroxylammonium salt from the catholyte compartment.
[0013]
In another embodiment, the present invention relates to a method for producing a hydroxylammonium salt by reducing a nitrogen-containing compound, wherein a mediator is used with the nitrogen-containing compound.
[0014]
In another embodiment, the present invention relates to a method for preparing hydroxylamine, the method comprising: an anode, a cathode, and a divider located between the cathode and the anode, the cathode and the divider Providing an electrochemical cell with a catholyte compartment between and a partition plate defining an anolyte compartment between the partition and the anode; the catholyte compartment with a hydroxylammonium salt And filling the anolyte compartment with a first electrolyte solution; passing a current through the electrochemical cell to produce hydroxylamine in the catholyte compartment And recovering the hydroxylamine from the catholyte compartment.
[0015]
In another embodiment, the invention relates to a method of making hydroxylamine from a hydroxylammonium salt in an electrochemical cell, wherein a mediator is used with the hydroxylammonium salt.
[0016]
In another embodiment, the present invention relates to a method of preparing a hydroxyammonium salt, the method comprising an anode, a cathode, and a divider located between the anode and the cathode, the cathode and the partition. A partition plate defining a catholyte compartment between the plate and an anolyte compartment between the anode and the partition plate, wherein the cathode has a film formed thereon from a mediator; Providing an electrochemical cell; filling the catholyte compartment with a first solution containing a nitrogen-containing compound and filling the anolyte compartment with a second solution containing an ionic compound; Passing an electric current through the electrochemical cell to produce a hydroxylammonium salt in the catholyte compartment; and Comprising the step of recovering from over de fluid compartment.
[0017]
In one embodiment, the present invention also provides an inexpensive and uncomplicated electrochemical method for efficiently preparing a variety of high purity compounds including, but not limited to, hydroxylammonium salts, hydroxylamine and adiponitrile.
[0018]
(Description of preferred embodiments)
In one embodiment, the present invention relates to a catalyst film and a method of forming the catalyst film. The catalyst film is formed on an electrode, typically in an electrochemical cell comprising at least a cathode, an anode, and a solution containing a film-forming compound and nitrate ions. In a preferred embodiment, the catalyst film is formed on the cathode of the electrochemical cell.
[0019]
While not wishing to be bound by any theory, it is believed that the interaction between the film-forming compound and nitrate ions forms a catalyst film on the electrode. The chemical identity of the catalyst film formed on the electrode due to the presence of the film-forming compound is unknown. However, the catalyst film is formed on the electrode substantially uniformly and smoothly. The catalyst film is typically dark orange to brown. This catalyst film is typically solid and porous. This film adheres strongly to the electrodes. This catalyst film has a pronounced catalytic effect that promotes at least one of the conversion of nitrogen-containing compounds to hydroxyammonium salts and the conversion of acrylonitrile to adiponitrile. While not wishing to be bound by any theory, this catalyst film increases the overvoltage for hydrogen evolution at the cathode, thereby facilitating the formation of products such as hydroxyammonium salts, hydroxylamine or adiponitrile. obtain.
[0020]
The thickness of the catalyst film formed on the electrode depends on the length of time that the film-forming compound and nitrate ions interact, the strength of the current, the relative concentration of the film-forming compound and nitrate ions, and other process parameters. It depends on various conditions such as The catalyst film typically has a thickness of at least about 0.1 nm, and typically from about 0.1 nm to about 500 μm. In another embodiment, the catalyst film has a thickness of at least about 0.5 nm, and typically from about 0.5 nm to about 100 μm. In another embodiment, the catalyst film has a thickness of at least about 1 nm, and typically from about 1 nm to about 10 μm.
[0021]
The catalyst film forms fairly rapidly during the first hour of the applied current and can last for at least 3 months (holding a pronounced catalytic effect). In this regard, once an electrode (such as a cathode) has such a catalyst film formed thereon, a film-forming compound in a solution that is loaded into an electrochemical cell for chemical processing. Need not be included. In other words, when an electrochemical cell comprising an electrode with such a catalyst film thereon is comprised, the solution that is refilled into the cell need contain only the reactants to produce the desired compound. There is.
[0022]
The mediator or film-forming compound includes an organic mediator or organic film-forming compound, and an inorganic mediator or inorganic film-forming compound. Organic film-forming compounds or organic mediators include one or more aromatic compounds and heterocyclic compounds that can form a catalyst film in the presence of nitrate ions. As used herein, the terms film-forming compound and mediator are interchangeable (they refer to the same compound); however, the term film-forming compound generally refers to the formation of a film that is not related to the use of the film. Used to indicate, while the term mediator is generally used to indicate the simultaneous use of a film to form a film and to form a final product such as a hydroxyammonium salt. Suitable film forming compounds or mediators include amino-aromatic compounds and quinone compounds. Specific examples of film forming compounds are: 1,4-phenylenediamine; 1,3-phenylenediamine; tetracyanoquinodimethane; N, N, N ′, N′-tetramethyl-p-phenylenediamine; p- Aminophenols such as aminophenol, m-aminophenol and o-aminophenol; aminothiophenol; tetrathiafulvalene; thianthrene; tri-Np-tolyamine; ferrocene; methylviologen dichloride Hydrates; quinone compounds such as hydroquinone, aminoanthraquinone, aminoanthraquinone-2-sulfonic acid sodium salt, anthraquinone-1,5-disulfonic acid disodium salt and anthraquinone-2,6-disulfonic acid disodium salt; , 4-bromo-2,3,5,6-tetrafluoroaniline, aniline compounds such as 4,4′-oxydianiline and 4′-aminoacetanilide; 1,10-phenanthroline; phenazine; 1,8-diamino Naphthalene; 1,4-diacetylbenzene; terephthaldicarboxaldehyde; terephthalic acid; and 2,5-dichloro-1,4-phenylenediamine.
[0023]
Inorganic mediators or inorganic film-forming compounds include metal mediators and non-organic mediators that can be reversibly reduced and oxidized. For example, each of the inorganic mediators is Me^{(n + x) +}And Me^{n +}A metal (expressed as Me) having an oxidized and reduced form such as The inorganic mediator includes at least one of a cesium compound, a chromium compound, a cobalt compound, a copper compound, a manganese compound, a periodate compound, a silver compound, a sodium compound, a tin compound, a titanium compound, and a lead compound. A specific example of an inorganic mediator is Ag²⁺/ Ag⁺, Ce⁴⁺/ Ce³⁺, Co³⁺/ Co²⁺, Cr³⁺/ Cr²⁺, Cu²⁺/ Cu⁺, Mn³⁺/ Mn²⁺, Sn²⁺/ Sn⁴⁺, Ti³⁺/ Ti⁴⁺, Zn²⁺/ Zn⁰, IO_Four ^-/ IO_Three ^-And Na⁺/ Na (Hg). The inorganic mediator can be added to the electrochemical cell in metallic form (adding metal powder) or in salt form. The above metal salts are known such as acetates, bromides, carbonates, chlorides, fluorides, iodides, nitrates, oxalates, phosphates and sulfate salts (the hydroxyl groups described below). (See also the various anions of ammonium salts), and therefore a long list is not included herein.
[0024]
The determination of whether a prospective compound can be classified as a film-forming compound is determined by whether the film formed by the prospective compound according to the present invention facilitates the conversion of the reactant compound to the desired compound. Including the evaluation. In one embodiment, the prospective compound converts the reactant to product at a faster rate than the conversion under the same conditions except that it forms a catalyst film and no catalyst film is used. Can be classified as film-forming compounds. In another embodiment, the promising compound is converted to the hydroxyammonium salt of the nitrogen-containing compound at a faster rate than the conversion under the same conditions except that it forms a catalyst film and no catalyst film is used. Can be classified as film-forming compounds. In yet another embodiment, the promising compound converts acrylonitrile to adiponitrile at a faster rate than conversion under the same conditions except that it forms a catalyst film and no catalyst film is used. When promoted, it can be classified as a film-forming compound.
[0025]
The nitrate ions can be obtained from one or more nitrate ion sources. Sources of nitrate ions include nitric acid, alkali metal nitrates (eg, sodium nitrate, potassium nitrate and rubidium nitrate), alkaline earth metal nitrates (eg, magnesium nitrate, calcium nitrate and strontium nitrate), transition metal nitrates (eg, copper nitrate, Nickel nitrate, manganese nitrate, silver nitrate, zinc nitrate, etc.), ammonium nitrate, quaternary ammonium nitrate (eg, tetramethylammonium nitrate, tetraethylammonium nitrate, tetrapropylammonium nitrate, tetrabutylammonium nitrate, tetra-n-octylammonium nitrate, nitric acid) Methyl triethylammonium, diethyldimethylammonium nitrate, methyltripropylammonium nitrate, methyltributylammonium nitrate, cetyltrimethylammonium nitrate, Methylhydroxyethylammonium nitrate, trimethylmethoxyethylammonium nitrate, dimethyldihydroxyethylammonium nitrate, methyltrihydroxyethylammonium nitrate, phenyltrimethylammonium nitrate, phenyltriethylammonium nitrate, benzyltrimethylammonium nitrate, and benzyltriethylammonium nitrate), quaternary phosphonium nitrate ( For example, tetramethylphosphonium nitrate, tetraethylphosphonium nitrate, tetrapropylphosphonium nitrate, tetrabutylphosphonium nitrate, tetramethylhydroxyethylphosphonium nitrate, dimethyldihydroxyethylphosphonium nitrate, methyltrihydroxyethylphosphonium nitrate, phenyltrimethylphosphonium nitrate, phenyltriethylphosphonium nitrate Honiumu and nitrate benzyltrimethylammonium phosphonium), and tertiary sulfonium nitrates (e.g., nitrate trimethylsulfonium, nitrate triethyl sulfonium, nitrate tripropylamine sulfonium and combinations thereof).
[0026]
Once the catalyst film is formed on the electrode (typically the cathode), the electrochemical cell can be emptied and a solution containing the reactants of the desired chemical reaction can fill the cell. Alternatively, the electrode coated with the catalyst film can be removed from the cell and transferred to another electrochemical cell where the desired chemical reaction takes place. Alternatively, the electrode coated with the catalyst film can be used during or after its formation without changing the solution by incorporating reactants of the desired chemical reaction into the cell with the mediator or film-forming compound. .
[0027]
Electrochemical cells suitable for the preparation of catalyst films can be considered to take many different configurations. In one embodiment, the electrochemical cell includes at least one compartment that includes an anode and a cathode (see FIG. 1). In a preferred embodiment, the electrochemical cell includes at least two compartments including an anode, a cathode and a divider (see FIG. 2). In another embodiment, the electrochemical cell includes at least three compartments including an anode, a cathode, a bipolar membrane, and a divider (see FIG. 3).
[0028]
In general, an electrochemical cell can be composed of a cell material, which is compatible with the material that is filled into the cell. It is essential that this cell material can be particularly resistant to acidic environments and often to basic environments.
[0029]
The cell can be adapted to operate at atmospheric or high pressure. In one embodiment, the cell is capable of operating at a high pressure of at least about 1 psig to about 10 psig or higher. Since the anode and cathode are not directly involved in the reaction, they can also be made from a variety of materials, but this material does not react with the solution added to the cell or the catalyst film formed in the cell.
[0030]
Suitable cathodes include carbon (eg, graphite), stainless steel, glassy carbon, titanium, titanium oxide ceramic, niobium, tungsten carbide, silver, lead, chromium, zinc, mercury, manganese dioxide or platinum. For example, the cathode may include tungsten carbide, activated carbon supported platinum, activated carbon supported silver, activated carbon supported manganese dioxide or platinized titanium. Graphite or carbon felt can be used with the cathode to increase the active surface area of the cathode. An Ebonex® cathode can also be used.
[0031]
In some embodiments, gas is introduced into the electrochemical cell and the cathode becomes a gas diffusion cathode. The gas diffusion cathode can include a conventional cathode structure formed from a suitable porous hydrophobic material such as polytetrafluoroethylene (PTFE), which is mixed with carbon black and an optional catalyst. Commercially available gas diffusion cathodes include ELAT type gas diffusion cathodes (which have a stainless steel mesh current collector integrated with an alloy of PtCo on hydrophobic PTFE containing Vulcan XC-72 carbon) and EFCG type gas diffusion cathodes ( This includes a stainless steel mesh current collector integrated with an alloy of PtCo on a Toray carbon substrate.
[0032]
A variety of materials can be used as the anode in an electrochemical cell. For example, the anode can be made from a metal, such as a coated titanium, tantalum, zirconium, hafnium or alloy thereof. In general, the anode has a non-passivated film and a catalyst film, which are noble metals (eg, platinum, iridium, rhodium, ruthenium or alloys thereof) or noble metals (eg, platinum, iridium, ruthenium, palladium or A mixture of electrically conductive oxides comprising at least one oxide of rhodium) or mixed oxides. In one embodiment, the anode is a dimensionally stable anode (eg, an anode having a titanium base thereon with ruthenium oxide and / or iridium oxide).
[0033]
Most electrochemical cells utilized in making and using the catalyst films of the present invention include at least one divider or separator (eg, an ionic or non-ionic selective membrane). This partition plate and / or bipolar membrane functions as a diffusion barrier and / or a gas separator.
[0034]
In one embodiment, this divider or separator that can be used in the present invention is a wide range of microporous with pores of the desired size that move anions and / or cations of various chemical compounds toward one of the electrodes. May be selected from diffusive diffusion barriers, screens, filters, partitions, and the like. The microporous divider can be prepared from a variety of materials including, for example, plastics such as polyethylene, polypropylene and Teflon, ceramics, and the like. Microporous partition plates (eg, non-ionic partition plates) can be used, for example, in addition to the partition plates listed in the drawings. Specific examples of commercially available microporous separators include: Celanese Celgard and Norton Zitex.
[0035]
In one embodiment, the divider is an anion selective membrane. Any anion selective membrane can be utilized, including a membrane used in a process for desalting brackish water. Preferably, an anion selective membrane should be selected with respect to the particular anion present in the cell (eg nitrate and halide ions). The preparation and structure of anionic membranes is described in Encyclopedia of Chemical Technology, Kirk-Othmer, 3rd edition, volume 15, chapter entitled “Membrane Technology”, pages 92-131, Wiley and Sons, New York, 198. . It is described in. These pages are incorporated herein by reference for disclosure of various anionic membranes that may be useful in the process of the present invention.
[0036]
Anion-selective membranes that can be utilized and are commercially available are: Fluoropolymer-based AMPLOON, Series 310 (produced by American Machine and Foundry Company) substituted with quaternary ammonium groups; Polymer based IONAC MA 3148, MA 3236 and MA 3475 (produced by Ritter-Pfowler Corp., Permutit Division) substituted with quaternary ammonium groups derived from functional polyvinyl chloride; Tosflex IE-SF 34 or IE-SA 48 (made by Tosoh Corp.), which is a membrane designed to be stable in alkaline media; Tokuyama Soda Co. NEOSEEPTA AMH, NEOSEPTTA ACM, NEOSEPTA AFN or NEOSEPTA ACLE-SP from; and Salemion AMV and Salemion AAV from Asahi Glass.
[0037]
In one embodiment, the divider is a cation selective membrane. The cation selective membrane used in the cell and process of the present invention can be any that has been utilized for electrochemical purification or recycling of chemical compounds. Preferably, the cation exchange membrane should comprise a very durable material such as a fluorocarbon series based membrane, or should consist of a cheaper material of the polystyrene or polypropylene series. Preferably, however, cation selective membranes useful in the present invention include cation selective groups such as perfluorosulfonic acid and perfluorosulfonic acid and perfluorocarboxylic acid, perfluorocarbon polymer membranes such as Fluoride membranes, including Dupont's Cationic Nafion 423 and 902 membranes, sold by EI DuPont Nemours & Co. under the generic trademark “Nafion”). Other suitable cation selective membranes include styrene divinylbenzene copolymer membranes containing cation selective groups such as sulfonate groups, carboxylate groups, and the like. Raipore Cation R1010 (from Pall RAI) and NEOSEPTTA CMH and NEOSEPTTA CM1 membranes from Tokuyama Soda are particularly useful for higher molecular compounds. The preparation and structure of cation-selective membranes is described in the chapter entitled “Membrane Technology” in Encyclopedia of Chemical Technology, Kirk-Othmer, 3rd edition, Volume 15, pages 92-131, Wiley and Sons, New Y, 1985. It is described in. These pages are incorporated herein by reference for disclosure of various cation selective membranes that may be useful in the present invention.
[0038]
Bipolar membranes used in electrochemical cells are composite membranes having three parts: a cation selective side or region, an anion selective side or region, and an interface between the two regions. When direct current passes through the bipolar membrane with a cation selective side facing the cathode or facing the cathode, electrical conduction is generated by the dissociation of water that occurs at the interface under the influence of the electric field.⁺And OH^-This is achieved by ion transport. Bipolar membranes are described, for example, in U.S. Pat. Nos. 2,829,095, 4,024,043 (single film bipolar membrane) and 4,116,889 (cast bipolar membrane). . Bipolar membranes useful in the present invention include NEOSEPTA BIPOLAR 1 (by Tokuyama Soda), WSI BIPOLAR, and Aquatics Bipolar membranes.
[0039]
In one embodiment, the electrochemical cell comprises at least one compartment. In a preferred embodiment, the electrochemical cell comprises at least two compartments; a catholyte compartment and an anolyte compartment. In another embodiment, the electrochemical cell comprises at least three compartments; that is, a catholyte compartment, an anolyte compartment and another compartment (eg, a buffer compartment, a pass compartment, Base compartment, acid compartment, etc.). The buffer compartment is typically placed between two bipolar membranes or between a bipolar membrane and an electrode. The pass compartment is typically placed between two cation selective membranes or two anion selective membranes and serves to further purify the final product. The base and acid are typically formed in the base compartment and the acid compartment, respectively.
[0040]
The electrochemical cell catholyte compartment (typically adjacent to the cathode) (or compartment of a one compartment cell) contains a solution of film forming compounds and nitrate ions. An aqueous solution is preferred. In one embodiment, the concentration of the film-forming compound can range from about 1 mM to about 1M. In another embodiment, the concentration of the film-forming compound ranges from about 5 mM to about 500 mM. In yet another embodiment, the concentration of the film-forming compound ranges from about 10 mM to about 100 mM. In one embodiment, the concentration of the nitrate ion source can range from about 0.001M to about 10M. In another embodiment, the nitrate ion source concentration ranges from about 0.01M to about 1M. In yet another embodiment, the nitrate ion source concentration ranges from about 0.1M to about 0.5M.
[0041]
The anolyte compartment of the electrochemical cell (generally adjacent to the anode) and the remaining compartment (if present) contain a solution of ionic compounds (electrolyte solution). An ionic compound is any compound that fully or partially ionizes in solution. Ionic compounds include acids, bases, and salts. An aqueous solution is preferred. The ionic compound in the anolyte compartment may be the same as or different from the ionic compound in any other compartment. Although any suitable ionic compound may be used in the anolyte compartment and other compartments, in a preferred embodiment, the ionic compounds in the anolyte compartment and other compartments are acid or nitrate ions. Is the source. The concentration of the ionic compound in the anolyte compartment and other compartments ranges from about 0.1M to about 10M, and preferably from about 2M to about 6M. The concentration of the ionic compound in the anolyte compartment may be the same as the concentration of the ionic compound in the other compartment, or it may be higher or lower.
[0042]
The current applied between the anode and cathode depends on the number of dividers (if any) placed between the anode and cathode and the concentration of the components. In one embodiment, the current density is from about 1 volt to about 10 volts and from about 2 volts to about 5 volts, each from about 0.01 ASI (ampere per square inch) to about 10 ASI, more often about 1 ASI-5 ASI is applied between the anode and cathode with an apparent current density. The current is applied to the electrochemical cell for a time effective to produce a catalyst film at the desired thickness on the cathode in the catholyte compartment (or compartment of the one compartment cell).
[0043]
The electrochemical cell can be maintained at a temperature suitable for the production of the catalyst film. This temperature typically ranges from about −20 ° C. to about 70 ° C. In another embodiment, the temperature ranges from about 1 ° C to about 30 ° C. The formation of the catalyst film can be monitored visually.
[0044]
Examples of electrochemical cells useful in the present invention are discussed below and are shown in FIGS.
[0045]
Referring to FIG. 1, an electrochemical cell 10 is made from a cathode 11 and an anode 12. The electrochemical cell 10 includes one compartment 13. In the operation of the electrochemical cell illustrated in FIG. 1, the compartment 13 is filled with a solution containing a film-forming compound and a nitrate ion source. A potential is established and maintained between the anode and the cathode to generate a current across the electrochemical cell; a catalyst film is then formed on the cathode 11 in the compartment 13.
[0046]
Referring to FIG. 2, the electrochemical cell 20 is made from a cathode 21, an anode 22, and a partition plate 23. The electrochemical cell 20 comprises two compartments; a catholyte compartment 24 and an anolyte compartment 25. In the operation of the electrochemical cell illustrated in FIG. 2, the catholyte compartment 24 is filled with a solution containing a film-forming compound and a nitrate ion source. The electrolyte solution containing the ionic compound is filled in the anolyte compartment 25. A potential is established and maintained between the anode and the cathode to generate a current across the electrochemical cell. At that time, a catalyst-forming film is produced on the cathode 21 in the catholyte compartment 24.
[0047]
Referring to FIG. 3, an electrochemical cell 30 is made from a cathode 31, an anode 32, and a bipolar membrane 33 and a divider 34 (starting with the cathode 31 in order). The bipolar membrane 33 has an anion selective side (not shown) facing the anode and a cation selective side (not shown) facing the cathode. The electrochemical cell 30 comprises three compartments; a catholyte compartment 35, a central compartment 36, and an anolyte compartment 37. In the operation of the electrochemical cell illustrated in FIG. 3, the catholyte compartment 35 is filled with a solution containing a film-forming compound and a nitrate ion source. The solution containing the ionic compound is filled in the central compartment 36 and the anolyte compartment 37. The ionic compound in the central compartment may be the same as or different from the ionic compound in the anolyte compartment. A potential is established and maintained between the anode and the cathode to generate a current across the electrochemical cell. At that time, the catalyst film is formed on the cathode 31 in the catholyte compartment 35.
[0048]
The following specific examples further illustrate the preparation of catalyst films according to the present invention. Unless otherwise indicated in the Examples and elsewhere in this specification and claims, all percentages or percentages are by weight, temperatures are in degrees Centigrade, and pressures are at or near atmospheric.
[0049]
(Example 1)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A solution containing 1 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3.5 volts are applied for 6 hours while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0050]
(Example 2)
An electrochemical cell according to FIG. 3 is provided. This includes an anode made of ruthenium oxide coated titanium, a stainless steel cathode, a Tokuyama Bipolar 1 bipolar membrane, an Asahi glass AAV anion selective membrane (as a divider). A 0.5 M nitric acid solution is placed in the central compartment. A solution of 0.3M nitric acid is placed in the anolyte compartment. A solution of 1.7 M hydroxylamine nitrate, 0.7 M nitric acid and 50 mM 1,4-phenylenediamine is then placed in the catholyte compartment. A 5 Amp current and a cell voltage of about 9.1 volts are applied for 2 hours while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0051]
(Example 3)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A graphite felt is attached to the graphite cathode to increase the active cathode surface area. A solution containing 1 M nitric acid and 50 mM to 100 mM anthraquinone-2,6-disulfonic acid disodium salt is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 15 Amp (1 ASI) and a cell voltage of about 3.5 volts are applied for 24 hours. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0052]
Example 4
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A graphite felt is attached to the graphite cathode to increase the active cathode surface area. A solution containing 1 M nitric acid and 50 mM to 400 mM 4,4'-oxydianiline is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 30 Amp (2 ASI) and a cell voltage of about 6 volts are applied for 8 hours. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0053]
(Example 5)
The general procedure of Example 1 is repeated. However, one graphite felt is attached to the graphite cathode to increase the cathode surface area. A solution containing 0.5 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 20 amp (5 ASI) and a cell voltage of about 5.5 volts are applied for 16 hours. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0054]
(Example 6)
The general procedure of Example 1 is repeated. However, a solution containing 1.0 M nitric acid and 70 ppm p-aminophenol is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 20 amp (5 ASI) and a cell voltage of about 5 volts are applied for 30 hours. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0055]
(Example 7)
The general procedure of Example 1 is repeated. However, a solution of 1 M nitric acid and 100 ppm hydroquinone is placed in the catholyte compartment. A solution of 4M nitric acid is added to the anolyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 20 amp (5 ASI) and a cell voltage of about 6.5 volts are applied for 1 hour. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0056]
(Example 8)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A solution containing 1 M sodium nitrate and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the sodium nitrate concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3.5 volts are applied for 6 hours while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A deep orange to brown color film forms uniformly on the cathode.
[0057]
Example 9
An electrochemical cell according to FIG. 1 is provided. This includes an anode made of ruthenium oxide coated titanium and a cathode made of graphite. A solution containing 1M tetrabutylammonium nitrate and 50 mM 1,4-phenylenediamine is placed in the compartment. Nitric acid is added to the compartment and the tetrabutylammonium nitrate concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3.5 volts are applied for 6 hours while maintaining the temperature between 5 ° C. and 10 ° C. Stir the compartment while applying current. A deep orange to brown color film forms uniformly on the cathode.
[0058]
The use of this cathode with a catalyst film thereon facilitates the synthesis of various compounds. For example, conversion of nitrogen-containing compounds to hydroxylammonium salts, conversion of hydroxylammonium salts to hydroxylamine, and conversion of acrylonitrile to adiponitrile are facilitated by the catalyst film of the present invention.
[0059]
Generally speaking, an electrochemical cell comprising an electrode having a catalyst film thereon is used to facilitate the synthesis of various compounds. In a preferred embodiment, the electrode is a cathode. The synthesis of various compounds can be performed in an electrochemical cell in which a catalyst film is formed. Alternatively, the electrode on which the catalyst film is formed can be transferred to another electrochemical cell. Some electrochemical cells suitable for the synthesis of certain compounds may comprise an electrode having a catalyst film thereon. For example, the electrochemical cell of FIGS. 2 and 3 is suitable for making hydroxylammonium salts and adiponitrile.
[0060]
The electrochemical cell may be operated batchwise or continuously. Circulation takes place by means of a pump and / or by outgassing. In one embodiment, the concentration of the ionic compound in the catholyte, anolyte, and / or recovery compartment is monitored by monitoring the supply to the compartment (eg, water supply to the anolyte compartment) and By using it, a substantially constant concentration is maintained.
[0061]
In one embodiment of the invention, the catalyst film is used to electrochemically convert nitrogen-containing compounds to hydroxylammonium salts or to convert hydroxylammonium salts to hydroxylamines. In particular, nitrogen-containing compounds are reduced to hydroxylammonium salts in the presence of films formed by film-forming compounds on the cathode. Referring to FIG. 2, a solution containing a nitrogen-containing compound is placed in the catholyte compartment 24. An electrolyte solution containing an ionic compound is placed in the anolyte compartment 25. In a preferred embodiment, the ionic compound is an acid. In this embodiment, the partition plate 23 is preferably a cation selective membrane. In some embodiments, additional dividers can be used in the cell. However, these are generally not necessary. When a potential is achieved and maintained between the anode and the cathode and a current is generated in the electrochemical cell, a hydroxylammonium salt is formed in the catholyte compartment 24. Hydroxyl ammonium salt is recovered from the catholyte compartment 24. The hydroxylammonium salt (or hydroxylamine described below) can be purified by further processing using one or more of distillation, reverse osmosis, electrodialysis and ion exchange methods.
[0062]
Ion exchange techniques using cation exchange resins and anion exchange resins are known to those skilled in the art. Distillation techniques are known to those skilled in the art. For example, the hydroxylammonium salt solution obtained from the catholyte compartment can be further purified using vacuum distillation.
[0063]
Reverse osmosis membranes are available from Fluid Systems, Filmtech, Osmonics, Inc. , Desalination Systems Inc. Etc. are commercially available. A specific example is a Fluid Systems TFCL-HP thin film composite membrane. Reverse osmosis membrane technology is known to those skilled in the art. For example, a hydroxylamine solution obtained from a catholyte compartment containing a hydroxylammonium salt is passed through a reverse osmosis membrane (eg, a polyamide-based membrane) under high pressure (100 psi or more, often 500 psi or more). Some compounds pass through this membrane. However, hydroxylammonium salts do not pass. Reverse osmosis membranes generally allow water and small molecular weight organics (eg, hydroxylamine) to pass through, but not ionic compounds.
[0064]
The hydroxylammonium salt solution obtained from the catholyte compartment can be further purified using electrodialysis in an electrodialysis cell. Electrodialysis techniques are known to those skilled in the art.
[0065]
These additional procedures are effective in removing impurities that may be present in the solution obtained from the compartment. Impurities include undesirable salts, ammonium ions, metals and organics.
[0066]
In embodiments where the hydroxylammonium salt is produced in the catholyte compartment, a current is applied between the anode and the cathode. Its apparent current density is about 0.1 ASI (ampere per square inch) to about 10 ASI at about 3 volts to about 4 volts, more frequently about 2 ASI to 4 ASI. The current is applied to the electrochemical cell for a time effective to produce hydroxylammonium salt in the catholyte compartment.
[0067]
The concentration of the nitrogen-containing compound in the catholyte compartment can be from about 0.01M to about 10M. Preferably, the nitrogen-containing compound concentration is about 0.5M to about 1M. The concentration of the ionic compound in the anolyte compartment can be from about 0.01M to about 5M. Preferably, the acid concentration is about 0.5M to about 1M.
[0068]
Nitrogen-containing compounds are compounds that have at least one nitrogen atom and can be converted to hydroxylammonium salts according to the invention. Examples of nitrogen-containing compounds include nitric acid, alkali metal nitrates (eg, sodium nitrate and potassium nitrate), alkaline earth metal nitrates (eg, magnesium nitrate and calcium nitrate), alkaline nitrites (eg, sodium nitrite and potassium nitrite), Alkaline earth metal nitrites, nitrides (eg, calcium nitride and magnesium nitride), organic nitro compounds (eg, nitromethane, nitroethane, nitropropane, nitrobutane, nitrobenzene, etc.) and nitrogen-containing gases.
[0069]
As used herein, a nitrogen-containing gas includes any gas containing nitrogen atoms. Examples of nitrogen-containing gases include nitrogen oxide gas and nitrogen-hydrogen gas. As used herein, nitrogen oxide gas is intended to mean a gas containing nitrogen and oxygen atoms. Examples of nitrogen oxide gases include one or more of nitric oxide (NO), nitrogen dioxide (NO₂), Nitric oxide (NO)_Three), Dinitrogen trioxide (N₂O_Three), Dinitrogen pentoxide (N₂O_Five). Examples of nitrogen-hydrogen gases are ammonia, hydrazine, and derivatives thereof. The nitrogen-containing gas can also be any gas containing at least a nitrogen-containing gas (eg, a mixture of one or more inert gases and nitrogen oxide gases). Inert gases include nitrogen and noble gases. Examples of noble gases are helium, neon, argon, krypton, xenon, and radon.
[0070]
In embodiments in which gas is introduced into the electrochemical cell (eg, a nitrogen-containing gas in the process for making the hydroxylammonium salt), the cathode is a gas diffusion cathode. In these embodiments, the electrochemical cell includes a gas chamber next to the gas diffusion cathode. Nitrogen-containing gas is injected into the gas chamber and then passed through the gas diffusion cathode and into the catholyte compartment. Such methods are described in US Pat. No. 5,447,610 and US application Ser. No. 08 / 734,858. Both of these are incorporated herein by reference. In one embodiment, the cathode can include a material that exhibits electrocatalytic activity for the reduction of nitrogen oxides to hydroxylamine or hydroxylammonium salts.
[0071]
A hydroxylammonium salt that can be produced in an electrochemical cell from a nitrogen-containing compound by the process of the present invention can be represented by the following formula:
(NR₂HOH)⁺ _yX^-y
Here, each R is independently hydrogen or a hydrocarbon group containing 1 to about 8 carbon atoms, preferably 1 to about 6 carbon atoms. X is an anion of an acid (eg, any of the above acids). And y is a number equal to the valence of X. Specific examples of anions include Cl^-, Br^-, SO_Four ^-2, HSO_Four ^-, NO_Three ^-, PO_Four ^-3, H₂PO_Four ^-1, HPO_Four ^-2Etc.
[0072]
Specific examples of hydroxylammonium salts that can be prepared according to the present invention may include: hydroxylammonium sulfate, hydroxylammonium nitrate, hydroxylammonium chloride, hydroxylammonium bromide, hydroxylammonium fluoride, hydroxylammonium formate. , Hydroxylammonium acetate, hydroxylammonium phosphate, hydroxylammonium methylsulfonate, hydroxylammonium toluenesulfonate, methylhydroxylammonium nitrate, ethylhydroxylammonium nitrate, propylhydroxylammonium nitrate, isopropylhydroxylammonium nitrate, and diethyl Hydroxylammonium nitrate, phenyl hydroxylammonium nitrate.
[0073]
The concentration of hydroxylammonium salt formed in the catholyte compartment can be from about 0.1M to about 10M. Preferably, the hydroxylammonium salt concentration in the catholyte compartment is from about 0.5M to about 2M.
[0074]
In one embodiment, the ionic compound is an acid and the acid solution is an acidic electrolyte. The acid lowers the pH of the neutral solution. The acid includes an organic acid and an inorganic acid. Preferably the acid is not reactive at the cathode.
[0075]
Formula H, which can be used with nitrogen-containing compounds in acidic electrolytes_YSpecific examples of the inorganic acid represented by X include at least one nitric acid, halogen acid (for example, hydrofluoric acid, hydrochloric acid, hydrobromic acid, and hydroiodic acid), sulfuric acid, sulfurous acid, perchloric acid, boron. Acids, and phosphorus-containing acids such as phosphoric acid and phosphorous acid. Nitric acid and sulfuric acid are preferred inorganic acids. Nitric acid and any other acid is a preferred acid combination. Formula H_YExamples of the organic acid represented by X include carboxylic acid and polycarboxylic acid. For example, formic acid, acetic acid, propionic acid, citric acid, oxalic acid, etc .; organic phosphorus-containing acids (eg, dimethylphosphoric acid and dimethylphosphinic acid); or sulfonic acids (eg, methanesulfonic acid, ethanesulfonic acid, 1-pentanesulfone) Acid, 1-hexanesulfonic acid, 1-heptanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid). Nitric acid and any other acid is a preferred combination of acids.
[0076]
In one embodiment, the ionic compound is a base and the base solution is a basic electrolyte. The base increases the pH of the neutral solution. The base includes an organic base and an inorganic base.
[0077]
Bases include alkali metal and alkaline earth metal hydroxides, silicates, phosphates, borates, carbonates, and mixtures thereof. For example, basic compounds include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal silicates, and the like. Alkali metals include lithium, sodium, potassium, rubidium and cesium. Alkaline earth metals include beryllium, magnesium, calcium, strontium and barium. Specific bases are: sodium tetraborate, sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium phosphate, sodium pyrophosphate and other polyphosphates, sodium silicate, potassium carbonate, potassium bicarbonate, Potassium hydroxide, potassium phosphate, potassium pyrophosphate and other polyphosphates, calcium carbonate, calcium hydroxide, calcium phosphate, calcium pyrophosphate, calcium silicate, magnesium carbonate, magnesium hydroxide, magnesium phosphate, magnesium pyrophosphate, and Magnesium silicate.
[0078]
Examples of electrochemical cells useful in the present invention are discussed below and are shown in FIGS. 1, 2, 3, 4, 5 and 6.
[0079]
As required, various compounds (eg, one or more acids, water, one or more ionic compounds, nitrogen-containing compounds, stabilizers, hydrogen inhibitors, etc.) can be added to the electrochemical cell. Can be added to or recovered from the catholyte compartment, anolyte compartment, and other compartments to maintain efficient operation of . For example, nitrogen-containing compounds must be added continuously or intermittently to the catholyte compartment. In some cases, it may be necessary to remove acid from the anolyte compartment intermittently or continuously.
[0080]
In one embodiment, the solution placed in the compartment in which the hydroxylammonium salt (or adiponitrile described below) is produced can also optionally include a hydrogen inhibitor. Examples of hydrogen inhibitors include thio compounds (eg, thiourea) and quaternary ammonium salts (eg, quaternary alkyl ammonium chlorides, nitrates, sulfates, bromides, phosphates, carbonates and bicarbonates). Can be mentioned. Specific examples of quaternary alkylammonium ions include: quaternary methylammonium, quaternary ethylammonium, quaternary propylammonium, quaternary butylammonium, dimethyldiethylammonium, methyltriethylammonium. Such. In one embodiment, the amount of hydrogen inhibitor in the solution can range from about 0.001% to about 10% by weight of the solution. In another embodiment, the amount of hydrogen inhibitor in the solution can range from about 0.01% to about 1% by weight of the solution.
[0081]
In another embodiment, the solution placed in the compartment in which the hydroxylammonium salt is produced can also optionally include a stabilizer. In some examples, the stabilizer inhibits the degradation of hydroxylammonium salt. Examples of stabilizers include: quinoline derivatives, thiocarboxylic acids, thiosulfates, hydroxyanthraquinones, and the like. Specific examples include 8-hydroxyquinoline, morin hydrate and quercetin. The amount of stabilizer in the solution is about 5 × 10 6 based on the weight of electrolyte present.^-FourIt can range from wt% to about 1 wt%.
[0082]
In one particular embodiment, where the hydroxylammonium salt is produced (starting with a solution containing a nitrogen-containing compound and an electrode having a mediator or mediator-forming film thereon), the electrochemical cell comprises an anode, a cathode, and A partition plate is included (see FIG. 2). In this embodiment, the divider plate is preferably a cation selective membrane. In some embodiments, additional dividers can be used in the cell. However, in general, these are not necessary.
[0083]
In one particular embodiment where hydroxylamine is produced (starting with a solution containing hydroxylammonium salt and an electrode having a mediator or mediator-forming film thereon), the electrochemical cell comprises an anode, a cathode, a bipolar membrane And a partition plate (see FIG. 3). In this embodiment, the divider plate is preferably an anion selective membrane. In some embodiments, additional dividers can be used in the cell. However, in general, these are not necessary.
[0084]
For example, in another specific embodiment where hydroxylamine is produced (starting with a solution containing hydroxylammonium salt and an electrode having a mediator or catalyst film thereon), the electrochemical cell comprises an anode, cathode, bipolar Includes a membrane and two dividers (see FIG. 4). In this embodiment, the two dividers comprise an anode next anion selective membrane and a bipolar membrane next cation selective membrane.
[0085]
In one particular embodiment where hydroxylamine is produced (starting with a solution containing hydroxylammonium salt and an electrode having a mediator or mediator-forming film thereon), the electrochemical cell comprises an anode, a cathode, and a partition Including a plate (see FIG. 5). In this embodiment, the divider plate is preferably an anion selective membrane and the cathode is preferably a gas diffusion cathode.
[0086]
In certain embodiments where both hydroxylammonium salt and hydroxylamine are produced in a single cell, the electrochemical cell comprises an anode, a cathode, a bipolar membrane, and a divider (see FIG. 6). In this embodiment, the divider plate is preferably an anion selective membrane.
[0087]
Thus, methods for producing hydroxylammonium salts from nitrogen-containing compounds involve the use of one electrochemical cell, while methods for producing hydroxylamines from nitrogen-containing compounds via hydroxylammonium salts include one or at least two Including the use of electrochemical cells. In an embodiment that uses two electrochemical cells to produce hydroxylamine, the hydroxylammonium salt is produced in a first electrochemical cell (eg, the cell of FIG. 2) and the hydroxylamine is produced in the second Manufactured in an electrochemical cell (eg, the cell of FIGS. 3, 4 or 5).
[0088]
In embodiments in which only hydroxylammonium salts are produced, hydroxylammonium salts and hydroxylamine are produced, or using cells that are the same or similar to the electrochemical cells of FIGS. 2 and 3, the catholyte compartment is Contains nitrogen-containing compound and mediator solution and optionally an acid. In embodiments where the cathode of the electrochemical cell has a film formed with a mediator thereon, the catholyte compartment contains a solution of a nitrogen-containing compound and optionally an acid (the mediator is excluded because it is a film). obtain). The choice of acid is determined by the particular hydroxylammonium salt desired to be produced. The acid may contain the desired hydroxyl ammonium salt anion. The concentration of the nitrogen-containing compound can be about 0.01M to 10M. Preferably, the concentration of the nitrogen-containing compound is about 0.5M to about 1M. The concentration of the mediator, when present, can be from about 1 mM to about 1M. Preferably, the mediator concentration, if present, is from about 10 mM to about 100 mM. The acid concentration can be from about 0.01M to about 5M. Preferably, the acid concentration is about 0.5M to about 1M.
[0089]
In embodiments that are intended to produce only hydroxylamine or that use the same or similar cell as the electrochemical cell of FIG. 3 or 4, the catholyte compartment is a solution of an ionic compound (electrolyte solution). including. Although any ionic compound may be used in the catholyte compartment, in a preferred embodiment, the ionic compound in the catholyte compartment is a base. In these embodiments, the concentration of the ionic compound in the catholyte compartment is from about 0.01M to about 10M, and preferably from about 0.1M to about 1M. The concentration of ionic compounds in the catholyte compartment can be the same, higher or lower than the concentration of ionic compounds in the other compartments present.
[0090]
In embodiments that are intended to produce only hydroxylamine or use cells that are the same or similar to the electrochemical cell of FIG. 5, the catholyte compartment contains a solution of hydroxylammonium salt and mediator. Others that are intended to produce only hydroxylamine or that use a cell that is the same or similar to the electrochemical cell of FIG. 5 and that has a film on which the cathode of the electrochemical cell is formed with a mediator In this embodiment, the catholyte compartment contains a solution of hydroxylammonium salt. The concentration of hydroxylammonium salt can be about 0.1M to 10M. Preferably, the concentration of hydroxylammonium salt concentration is from about 0.5M to about 2M. The concentration of the mediator, when present, can be from about 1 mM to about 1M. Preferably, the mediator concentration, if present, is from about 10 mM to about 100 mM.
[0091]
The collection compartment of the electrochemical cell (generally next to the intermediate compartment and / or the bipolar membrane) initially contains a solution containing an ionic compound as required. The ionic compounds in the recovery compartment can be the same or different from the ionic compounds in the other compartments present. The concentration of the ionic compound in the recovery compartment is about 0.01M to 10M, and preferably about 0.1M to about 0.5M. The concentration of the ionic compound in the recovery compartment can be the same, higher or lower than the concentration of the ionic compound in the other compartment. In some embodiments (see, eg, FIG. 3), this collection compartment is charged with a solution of hydroxylammonium salt and mediator (if there is no film formed of mediator on the cathode). The concentration of hydroxylammonium salt can be about 0.1M to 10M. Preferably, the hydroxylammonium salt concentration is about 0.5M to about 2M. The concentration of the mediator, when present, can be from about 1 mM to about 1M. Preferably, the mediator concentration, if present, is from about 10 mM to about 100 mM. In the embodiment of FIG. 4, this feed compartment (typically an intermediate compartment), if present, is charged with a solution of hydroxylammonium salt and mediator (same concentration as above), and the recovery compartment is optional. A solution having the following ionic compound.
[0092]
The concentration of hydroxylammonium salt produced in the catholyte compartment is about 0.1M to 10M, and preferably about 0.5M to about 2M. A portion of the hydroxylammonium salt produced in the catholyte compartment is then either recovered or physically transferred to another electrochemical cell or the recovery compartment of the same cell (See, for example, FIG. 6). This can be accomplished on a basis either intermittently or continuously by means known to those skilled in the art. The concentration of hydroxylamine produced in the recovery compartment is from about 0.1M to about 16M, and preferably from about 2M to about 5M.
[0093]
Referring to FIG. 6, an electrochemical cell 60 is made with an array of bipolar membranes 63 and dividers 64 starting with a cathode 61, an anode 62, and a cathode 61. In a preferred embodiment, the partition plate 64 is an anion selective membrane. The bipolar membrane 63 has an anion selective side (not shown) facing the anode and a cation selective side (not shown) facing the cathode. The electrochemical cell 60 comprises three compartments; a catholyte compartment 65, a recovery compartment 66 and an anolyte compartment 67.
[0094]
In the operation of the electrochemical cell shown in FIG. 6, a solution containing a nitrogen-containing compound and a mediator is charged to the catholyte compartment 65. The electrolyte solution containing the ionic compound is charged into the recovery compartment 66 and the anolyte compartment 67. The ionic compound has a first concentration in the recovery compartment and a second concentration in the anolyte compartment 67. A potential is established and maintained between the anode and cathode to generate a current across the electrochemical cell, resulting in the production of hydroxylammonium salt in the catholyte compartment 65. Whether a portion of the catholyte solution containing the hydroxylammonium salt is recovered or physically removed from the catholyte compartment 65 and transferred to the recovery compartment 66 as indicated by line 68 Either. As a result of the potential maintained between the anode and cathode, the salt (anion) of the hydroxylammonium salt is attracted towards the anode 62, thereby passing through the partition plate 64 to the anolyte compartment 67. enter. Hydroxylamine is produced in the recovery compartment 66. Hydroxylamine is then produced in the recovery compartment 66. The hydroxylamine is then recovered from the recovery compartment 66. Hydroxylamine and / or hydroxylammonium salt (before being charged to the recovery compartment) can be purified by further processing using one or more distillations, reverse osmotic pressure, electrodialysis and ion exchange techniques.
[0095]
In a preferred embodiment, a portion of the solution in the anolyte compartment can be physically removed and transferred to the catholyte compartment 65 as indicated by line 69. In a still further preferred embodiment, the acid solution obtained from this anolyte compartment is concentrated before being added to the catholyte compartment. As a salt, the anion from the hydroxylammonium salt passes through the partition plate 64 and moves to the anolyte compartment 67, and an acid corresponding to this salt is produced in the anolyte compartment.
[0096]
Various compounds (eg, one or more acids, water, one or more ionic compounds, nitrogen-containing compounds, mediators, stabilizers, etc.) to maintain efficient operation of the electrochemical cell as required. Can be added or recovered from the catholyte compartment, the recovery compartment and the anolyte compartment. For example, nitrogen-containing compounds must be added continuously or intermittently to the catholyte compartment. Sometimes it may also be necessary to remove acid from the anolyte compartment intermittently or continuously.
[0097]
Although the embodiment described in FIG. 6 illustrates the formation of a general hydroxylammonium salt, the described electrochemical cell and method employs a number of desired unique hydroxyls by utilizing the different acids described above. It can be utilized to prepare ammonium salts. Therefore, hydroxylammonium chloride salt can be prepared by utilizing a hydrochloric acid solution, hydroxylammonium sulfate can be prepared by utilizing a sulfuric acid solution, and hydroxylammonium nitrate can be prepared by utilizing a nitric acid solution. Hydroxyl ammonium borate can be prepared by utilizing boric acid and formate and acetate can be prepared by utilizing formic acid and acetic acid.
[0098]
Referring to FIG. 2, the electrochemical cell 20 is made from a cathode 21, an anode 22, and a partition plate 23. In a preferred embodiment, the partition plate 23 is a cation selective membrane. The electrochemical cell 20 comprises two compartments; a catholyte compartment 24 and an anolyte compartment 25.
[0099]
In the operation of the electrochemical cell illustrated in FIG. 2, a solution containing a nitrogen-containing compound and a mediator is charged to the catholyte compartment 24. The anolyte compartment 25 is charged with an electrolyte solution containing an ionic compound. In a preferred embodiment, the ionic compound is an acid. A potential is established and maintained between the anode and cathode to generate a current across the electrochemical cell, resulting in the production of hydroxylammonium salt in the catholyte compartment 24. Hydroxyl ammonium salt is recovered from the catholyte compartment 24. The hydroxylammonium salt can be purified by further processing using one or more distillation, reverse osmotic pressure, electrodialysis and ion exchange techniques.
[0100]
Referring to FIG. 3, the electrochemical cell 30 is made with a cathode 31, an anode 32, and an array of bipolar membranes 33 and dividers 34 starting with the cathode 31. In a preferred embodiment, the partition plate 34 is an anion selective membrane. The bipolar membrane 33 has an anion selective side (not shown) facing the anode and a cation selective side (not shown) facing the cathode. The electrochemical cell 30 comprises three compartments; a catholyte compartment 35, a recovery compartment 36 and an anolyte compartment 37.
[0101]
In the operation of the electrochemical cell shown in FIG. 3, a solution containing hydroxylammonium salt and mediator is charged into the recovery compartment 36. The catholyte compartment 35 and the anolyte compartment 37 are charged with a solution containing an ionic compound. The ionic compound in the catholyte compartment is the same as or different from the ionic compound in the anolyte compartment. In a preferred embodiment, the ionic compound in the catholyte compartment is a base while the ionic compound in the anolyte compartment is an acid. A potential is established and maintained between the anode and cathode to generate an electric current across the electrochemical cell, resulting in the production of hydroxylamine in the recovery compartment 36. As a result of the potential maintained between the anode and cathode, the salt (anion) of the hydroxylammonium salt is attracted towards the anode 32, thereby passing through the divider 34 to the anolyte compartment 37. enter. Next, hydroxylamine is recovered from the recovery compartment 36. Hydroxylamine can be purified by further processing using one or more distillations, reverse osmotic pressure, electrodialysis and ion exchange techniques.
[0102]
Referring to FIG. 4, an electrochemical cell 40 is made with a cathode 41, an anode 42, and an array of a bipolar membrane 43, a first divider 44 and a second divider 45 starting with the cathode 41. In a preferred embodiment, the first divider 44 is a cation selective membrane and the second divider is an anion selective membrane. The bipolar membrane 43 has an anion selective side (not shown) facing the anode and a cation selective side (not shown) facing the cathode. The electrochemical cell 40 comprises four compartments; a catholyte compartment 46, a recovery compartment 47, a supply compartment 48 and an anolyte compartment 49.
[0103]
In the operation of the electrochemical cell shown in FIG. 4, a solution containing hydroxylammonium salt and mediator is charged to the supply compartment 48. The solution containing the ionic compound is charged into the catholyte compartment 35 and the anolyte compartment 37. A solution containing an ionic compound is charged into the collection compartment 47 as necessary. The ionic compound in the catholyte compartment is the same as or different from the ionic compound in the anolyte compartment (and / or the recovery compartment). In a preferred embodiment, the ionic compound in the catholyte compartment is a base while the ionic compound in the anolyte compartment is an acid. A potential is established and maintained between the anode and cathode to generate an electric current across the electrochemical cell, resulting in the production of hydroxylamine in the recovery compartment 47. As a result of the potential maintained between the anode and cathode, the salt (anion) of the hydroxylammonium salt is attracted towards the anode 42 and thereby passes through the second divider 45 to the anolyte compartment. Enter 49. Next, hydroxylamine is recovered from the recovery compartment 47. Hydroxylamine can be purified by further processing using one or more distillations, reverse osmotic pressure, electrodialysis and ion exchange techniques.
[0104]
Referring to FIG. 5, the electrochemical cell 50 is made from a cathode 51, an anode 52 and a partition plate 53. In a preferred embodiment, divider 53 is an anion selective membrane and the cathode is a gas diffusion cathode. Electrochemical cell 50 comprises two compartments; a catholyte compartment 54 and an anolyte compartment 55.
[0105]
In operation of the electrochemical cell shown in FIG. 5, a solution containing hydroxylammonium salt and mediator is charged to the catholyte compartment 54. The solution containing the ionic compound is charged into the anolyte compartment 55. In a preferred embodiment, the ionic compound in the anolyte compartment is an acid. A potential is established and maintained between the anode and cathode to generate a current across the electrochemical cell, which results in the production of hydroxylamine in the catholyte compartment 54. As a result of the potential maintained between the anode and cathode, the salt (anion) of the hydroxylammonium salt is attracted towards the anode 52, thereby passing through the partition plate 53 to the anolyte compartment 55. enter. Hydroxylamine is then recovered from the catholyte compartment 54. Hydroxylamine can be purified by further processing using one or more distillations, reverse osmotic pressure, electrodialysis and ion exchange techniques.
[0106]
In another embodiment of the invention, a catalyst film is used to electrochemically convert acrylonitrile to adiponitrile. Specifically, acrylonitrile is converted to adiponitrile in the presence of a film formed by a film-forming compound on the cathode. Referring to FIG. 2, the catholyte compartment 24 is charged with a solution containing acrylonitrile. The anolyte compartment 25 is charged with an electrolyte solution containing an ionic compound. In a preferred embodiment, the ionic compound is an acid. In this embodiment, the partition plate 23 is preferably a cation selective membrane. In some embodiments, additional dividers may be used in the cell, but they are generally not required. A potential is established and maintained between the anode and the cathode to generate a current across the electrochemical cell, resulting in the production of adiponitrile in the catholyte compartment 24. Adiponitrile is recovered from the catholyte compartment 24. Adiponitrile can be purified by further processing using one or more distillations, reverse osmotic pressure, electrodialysis and ion exchange techniques.
[0107]
In embodiments in which adiponitrile is produced in the catholyte, an apparent current between the anode and cathode of about 0.1 ASI (amps per square inch) to about 10 ASI, more often about 2 ASI to 4 ASI. The current density is applied from about 3 volts to about 4 volts. An electric current is applied to the electrochemical cell for a time effective to produce adiponitrile in the catholyte compartment.
[0108]
The concentration of acrylonitrile in the catholyte compartment can be from about 0.01M to about 10M. Preferably, the acrylonitrile concentration is from about 0.5M to about 1M. The concentration of the ionic compound in the anolyte compartment can be from about 0.01M to about 5M. Preferably, the concentration of the ionic compound is from about 0.5M to about 1M. The ionic compound is as described above.
[0109]
The concentration of adiponitrile formed in the catholyte compartment can be about 0.1M to 10M. Preferably, the concentration of adiponitrile formed in the catholyte compartment is from about 0.5M to about 2M.
[0110]
The following detailed examples further illustrate the preparation of hydroxylammonium salts and hydroxylamines according to the present invention. Unless otherwise indicated in the examples and elsewhere in the specification and claims, all parts and percentages are parts by weight and percentages by weight, temperatures are in degrees Centigrade, and pressures are at standard atmospheric pressure. Or near standard atmospheric pressure.
[0111]
(Example 10)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 1, and a Nafion 423 cation selective membrane as a divider. A solution containing 1M nitric acid is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.8 M nitric acid and 1.3 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 60% is achieved for the formation of hydroxylammonium nitrate.
[0112]
(Example 11)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 3, and a Nafion 423 cation selective membrane as a divider. A solution containing 1M nitric acid is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 15 Amp (1 ASI) and a cell voltage of about 3.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 1.1M hydroxylammonium nitrate and 0.9M nitric acid and 0.05M ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 35% is achieved for the formation of hydroxylammonium nitrate.
[0113]
Example 12
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 4, and a Nafion 423 cation selective membrane as a divider. A solution containing 1M nitric acid is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 30 Amp (2 ASI) and a cell voltage of about 6 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.8M nitric acid and 1.9M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 60% is achieved for the formation of hydroxylammonium nitrate.
[0114]
(Example 13)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 4, and a Nafion 423 cation selective membrane as a divider. A solution containing 1M nitric acid is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 15 Amp (1 ASI) and a cell voltage of about 4.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 1.2M hydroxylammonium nitrate and 1.2M nitric acid and 0.1M ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 40% is achieved for the formation of hydroxylammonium nitrate.
[0115]
(Example 14)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of niobium, and a Nafion 423 cation selective membrane as a divider. A solution containing 1 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A film forms on the cathode after about 1 hour. A solution of 0.8M hydroxylammonium nitrate and 0.9M nitric acid and 0.03M ammonium nitrate is then obtained from the catholyte compartment. An overall current efficiency of 45% is achieved for the formation of hydroxylammonium nitrate.
[0116]
(Example 15)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 5, and a Nafion 423 cation selective membrane as a divider. A solution containing 0.5M nitric acid is placed in the catholyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 20 Amp (5 ASI) and a cell voltage of about 5.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.50 M nitric acid and 1.67 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 85% is achieved for the formation of hydroxylammonium nitrate.
[0117]
(Example 16)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 6, and a Nafion 423 cation selective membrane as a divider. A solution containing 1.0 M nitric acid is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 20 Amp (5 ASI) and a cell voltage of about 5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. A solution of 0.7 M nitric acid and 1.26 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 74% is achieved for the formation of hydroxylammonium nitrate.
[0118]
(Example 17)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 7, and a Nafion 423 cation selective membrane as a divider. A solution of 1M nitric acid is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 20 Amp (5 ASI) and a cell voltage of about 6.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. A solution of 0.8 M nitric acid and 1.3 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 60% is achieved for the formation of hydroxylammonium nitrate.
[0119]
(Example 18)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 1, and a Nafion 423 cation selective membrane as a divider. A solution of 1M hydrochloric acid and 1M nitrobenzene is placed in the catholyte compartment of the cell. A solution of 4M nitric acid is placed in the anolyte compartment. While maintaining the temperature between 25 ° C. and 30 ° C., a current of 10 amp (2.5 ASI) and a cell voltage of about 5.5 volts are applied. The catholyte is stirred while applying an electric current. A solution of 0.9M phenylhydroxylammonium chloride is obtained from the catholyte compartment. An overall current efficiency of 55% is achieved for the formation of phenylhydroxylammonium chloride.
[0120]
(Example 19)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 1, and a Nafion 423 cation selective membrane as a divider. The general procedure of Example 10 is repeated. However, thiourea is also added into the catholyte compartment. A solution of 1 M nitric acid and 250 mM thiourea is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 45 amp (3 ASI) and a cell voltage of about 6.5 volts are applied. The catholyte is stirred while applying an electric current. A solution of 0.5 M nitric acid and 1.77 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 90% is achieved for the formation of hydroxylammonium nitrate.
[0121]
(Example 20)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 1, and a Nafion 423 cation selective membrane as a divider. The general procedure of Example 10 is repeated. However, tetrabutylammonium chloride is added into the catholyte compartment. A solution of 1M nitric acid and 0.1M tetrabutylammonium chloride is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 45 amp (3 ASI) and a cell voltage of about 6.5 volts are applied. The catholyte is stirred while applying an electric current. A solution of 0.7 M nitric acid and 1.65 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 85% is achieved for the formation of hydroxylammonium nitrate.
[0122]
(Example 21)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 1, and a Nafion 423 cation selective membrane as a divider. The general procedure of Example 10 is repeated. However, a solution containing 1M nitrobenzene is also added into the catholyte compartment of the cell. A solution of 4M nitric acid is placed in the anolyte compartment. While maintaining the temperature between 25 ° C. and 30 ° C., a current of 10 amp (2.5 ASI) and a cell voltage of about 5.5 volts are applied. The catholyte is stirred while applying an electric current. A solution of 0.9M phenylhydroxylammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 55% is achieved for the formation of phenylhydroxylammonium nitrate.
[0123]
(Example 22)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made according to Example 3, and a Nafion 423 cation selective membrane as a divider. The general procedure of Example 10 is repeated. However, 1.5M acrylonitrile and 0.2M tetraethylammonium p-toluenesulfonate are added into the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. A current of 12 amp (3 ASI) and a cell voltage of about 4.50 volts are applied while maintaining the temperature between 25 ° C. and 30 ° C. A solution of 0.45 M adiponitrile is obtained from the catholyte compartment. An overall current efficiency of 95% is achieved for the formation of adiponitrile.
[0124]
(Example 23)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A solution containing 1 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.8 M nitric acid and 1.3 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 60% is achieved for the formation of hydroxylammonium nitrate.
[0125]
(Example 24)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A graphite felt is attached to the graphite cathode to increase the active cathode surface area. A solution containing 1 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 45 Amp (3 ASI) and a cell voltage of about 6.5 volts are applied. The catholyte is stirred while applying an electric current. A solution of 0.6 M nitric acid and 1.7 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 75% is achieved for the formation of hydroxylammonium nitrate.
[0126]
(Example 25)
An electrochemical cell according to FIG. 3 is provided. This includes an anode made of ruthenium oxide coated titanium, a stainless steel cathode, a Tokuyama Bipolar 1 bipolar membrane, an Asahi glass AAV anion selective membrane (as a divider). A solution of 0.5M sodium hydroxide is placed in the catholyte compartment. A solution of 0.3M nitric acid is placed in the anolyte compartment. Then 1.7 M hydroxylamine nitrate, 0.7 M nitric acid and 50 mM 1,4-phenylenediamine are placed in the recovery compartment. A 5 Amp current and a cell voltage of about 9.1 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. A solution containing 1.6 M hydroxylamine and 50 mM 1,4-phenylenediamine is collected from the collection compartment. Pure hydroxylamine is obtained after purification by distillation.
[0127]
(Example 26)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A graphite felt is attached to the graphite cathode to increase the active cathode surface area. A solution containing 1 M nitric acid and 50 mM to 100 mM anthraquinone-2,6-disulfonic acid disodium salt is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 15 Amp (1 ASI) and a cell voltage of about 3.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 1.1M hydroxylammonium nitrate and 0.9M nitric acid and 0.05M ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 35% is achieved for the formation of hydroxylammonium nitrate.
[0128]
(Example 27)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. A graphite felt is attached to the graphite cathode to increase the active cathode surface area. A solution containing 1 M nitric acid and 50 mM to 400 mM 4,4'-oxydianiline is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 30 Amp (2 ASI) and a cell voltage of about 6 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.8M nitric acid and 1.9M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 60% is achieved for the formation of hydroxylammonium nitrate.
[0129]
(Example 28)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of graphite, and a Nafion 423 cation selective membrane as a divider. Carbon felt is attached to the graphite cathode to increase the active cathode surface area. A solution containing 1 M nitric acid and 50 mM to 0.1 M tin chloride is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 15 Amp (1 ASI) and a cell voltage of about 4.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 1.2M hydroxylammonium nitrate and 1.2M nitric acid and 0.1M ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 40% is achieved for the formation of hydroxylammonium nitrate.
[0130]
(Example 29)
An electrochemical cell according to FIG. 2 is provided. This includes an anode made of ruthenium oxide coated titanium, a cathode made of niobium, and a Nafion 423 cation selective membrane as a divider. A solution containing 1 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 5 Amp (0.3 ASI) and a cell voltage of about 3 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.8M hydroxylammonium nitrate and 0.9M nitric acid and 0.03M ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 45% is achieved for the formation of hydroxylammonium nitrate.
[0131]
(Example 30)
The general procedure of Example 23 is repeated. However, one graphite felt is attached to the graphite cathode to increase the cathode surface area. A solution containing 0.5 M nitric acid and 50 mM 1,4-phenylenediamine is placed in the catholyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 20 amp (5 ASI) and a cell voltage of about 5.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.50 M nitric acid and 1.67 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 85% is achieved for the formation of hydroxylammonium nitrate.
[0132]
(Example 31)
The general procedure of Example 30 is repeated. However, a solution containing 1.0 M nitric acid and 70 ppm p-aminophenol is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 20 amp (5 ASI) and a cell voltage of about 5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. A solution of 0.7 M nitric acid and 1.26 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 74% is achieved for the formation of hydroxylammonium nitrate.
[0133]
(Example 32)
The general procedure of Example 30 is repeated. However, a solution of 1 M nitric acid and 100 ppm hydroquinone is placed in the catholyte compartment. A solution of 4M nitric acid is added to the anolyte compartment. Concentrated nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 20 amp (5 ASI) and a cell voltage of about 6.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. A solution of 0.8 M nitric acid and 1.3 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 60% is achieved for the formation of hydroxylammonium nitrate.
[0134]
(Example 33)
The general procedure of Example 30 is repeated. However, thiourea is also added to the catholyte compartment. A solution of 1M nitric acid, 50 mM 1,4-phenylenediamine and 250 mM thiourea is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. A current of 45 amp (3 ASI) and a cell voltage of about 6.5 volts are applied while maintaining the temperature between 5 ° C. and 10 ° C. The catholyte is stirred while applying an electric current. A solution of 0.5 M nitric acid and 1.77 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 90% is achieved for the formation of hydroxylammonium nitrate.
[0135]
(Example 34)
The general procedure of Example 30 is repeated. However, tetrabutylammonium chloride is added to the catholyte compartment. A solution of 1M nitric acid, 50 mM 1,4-phenylenediamine and 0.1M tetrabutylammonium chloride is placed in the catholyte compartment. A solution of 4M nitric acid is placed in the anolyte compartment. Nitric acid is added to the catholyte compartment and the nitric acid concentration is maintained between 0.5M and 1M while applying current. While maintaining the temperature between 5 ° C. and 10 ° C., a current of 45 amp (3 ASI) and a cell voltage of about 6.5 volts are applied. The catholyte is stirred while applying an electric current. A solution of 0.7 M nitric acid and 1.65 M hydroxylammonium nitrate without detectable ammonium nitrate is obtained from the catholyte compartment. An overall current efficiency of 85% is achieved for the formation of hydroxylammonium nitrate.
[0136]
The present invention provides an efficient, low-cost, and uncomplicated electrochemical process for the preparation of high purity hydroxylammonium salts, hydroxylamine and adiponitrile. Since the use of mercury-containing and / or lead-containing cathodes is not required, the present invention does not cause toxicity concerns and is environmentally friendly. In some embodiments, since the use of a gas permeable cathode is not required, the present invention is simple to implement at a relatively low cost.
[0137]
The description has been made in connection with a preferred embodiment of the present invention. However, it should be understood that various modifications thereof will be apparent to those skilled in the art upon reading this specification. Accordingly, it is to be understood that the invention disclosed herein is intended to include such modifications within the scope of the appended claims.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an electrochemical cell useful in the preparation of a catalyst film according to the present invention.
FIG. 2 is a schematic cross-sectional view of an electrochemical cell useful in the preparation of a catalyst film according to the present invention.
FIG. 3 is a schematic cross-sectional view of an electrochemical cell useful in preparing a catalyst film according to the present invention.
FIG. 4 is a schematic cross-sectional view of an electrochemical cell useful in the preparation of hydroxyammonium salts and hydroxylamine according to the present invention.
FIG. 5 is a schematic cross-sectional view of an electrochemical cell useful in the preparation of hydroxyammonium salts and hydroxylamines according to the present invention.
FIG. 6 is a schematic cross-sectional view of an electrochemical cell useful in the preparation of hydroxyammonium salts and hydroxylamines according to the present invention.

Claims (16)

  A catalyst film made by applying an electric current to an electrochemical cell comprising a solution comprising two electrodes and a film-forming compound and a nitrate ion source.   The catalyst film of claim 1, wherein the electrochemical cell comprises a partition plate between the anode and the cathode.   The catalyst film of claim 1, wherein the film-forming compound comprises at least one of an amino-aromatic compound and a quinone compound.   The film-forming compound is 1,4-phenylenediamine; 1,3-phenylenediamine; tetracyanoquinodimethane; N, N, N ′, N′-tetramethyl-p-phenylenediamine; p-aminophenol; m-aminophenol; o-aminophenol; aminothiophenol; tetrathiafulvalene; thianthrene; tri-Np-tolyamine; ferrocene; methyl viologen dichloride hydrate; hydroquinone; amino Anthraquinone; aminoanthraquinone-2-sulfonic acid sodium salt; anthraquinone-1,5-disulfonic acid disodium salt; anthraquinone-2,6-disulfonic acid disodium salt; acetanilide, 4-bromo-2,3,5,6- Tetrafluoroaniline, 4,4'-oxydianiline; 4'-aminoacetanilide; 1,10-phenanthroline; phenazine; 1,8-diaminonaphthalene; 1,4-diacetylbenzene; terephthaldicarboxaldehyde; terephthalic acid; The catalyst film according to claim 1, comprising at least one of dichloro-1,4-phenylenediamine.   The nitrate ion source comprises at least one of nitric acid, alkali metal nitrate, alkaline earth metal nitrate, transition metal nitrate, ammonium nitrate, quaternary ammonium nitrate, quaternary phosphonium nitrate, and tertiary sulfonium nitrate. The catalyst film according to claim 1.   The catalyst film of claim 1, wherein the catalyst film has a thickness of about 0.1 nm to about 500 μm. A method of making a catalyst film comprising:
Applying an electric current to an electrochemical cell comprising an anode, a cathode, and a solution comprising a film-forming compound and a source of nitrate ions, thereby forming the catalyst film.   The method of claim 7, wherein the catalyst film is formed on the cathode.   8. The solution of claim 7, wherein the solution has a temperature of about -20C to about 70C and the current is about 1 A to about 10 V and has an apparent current density of about 0.1 ASI to about 10 ASI. The method described.   The solution comprises from about 1 mM to about 1 M of the film-forming compound and from about 0.01 M to about 1 M of the nitrate ion source, and from about 1 mM to about 1 M of the film-forming compound and from about 0.1 M to about 0. 8. The method of claim 7, comprising 5M of the nitrate ion source.   The film-forming compound is 1,4-phenylenediamine; 1,3-phenylenediamine; tetracyanoquinodimethane; N, N, N ′, N′-tetramethyl-p-phenylenediamine; p-aminophenol; m-aminophenol; o-aminophenol; aminothiophenol; tetrathiafulvalene; thianthrene; tri-Np-tolyamine; ferrocene; methyl viologen dichloride hydrate; hydroquinone; amino Anthraquinone; aminoanthraquinone-2-sulfonic acid sodium salt; anthraquinone-1,5-disulfonic acid disodium salt; anthraquinone-2,6-disulfonic acid disodium salt; acetanilide, 4-bromo-2,3,5,6- Tetrafluoroaniline, 4,4'-oxydianiline; 4'-aminoacetanilide; 1,10-phenanthroline; phenazine; 1,8-diaminonaphthalene; 1,4-diacetylbenzene; terephthaldicarboxaldehyde; terephthalic acid; The method of claim 7, comprising at least one of dichloro-1,4-phenylenediamine. A catalyst film formed on the cathode made by applying an electric current to a first electrochemical cell comprising an anode and a cathode and a film-forming solution comprising a film-forming compound and a source of nitrate ions. The method to use is:
Providing a second electrochemical cell comprising an anode, a cathode having the catalyst film, and a reactant solution comprising the reactant;
Applying a current to the second electrochemical cell; and recovering a product from the second electrochemical cell.   13. The method of claim 12, wherein the first electrochemical cell and the second electrochemical cell are the same electrochemical cell.   13. The method of claim 12, wherein the first electrochemical cell and the second electrochemical cell are different electrochemical cells.   13. The method of claim 12, wherein the reactant comprises a nitrogen containing compound and the product comprises a hydroxylammonium salt.   13. The method of claim 12, wherein the reactant comprises acrylonitrile and the product comprises adiponitrile.

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