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CN113663674B - A preparation method and application of porous microspheres and a reduction method of nitro compounds - Google Patents

A preparation method and application of porous microspheres and a reduction method of nitro compounds Download PDF

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CN113663674B
CN113663674B CN202010412632.4A CN202010412632A CN113663674B CN 113663674 B CN113663674 B CN 113663674B CN 202010412632 A CN202010412632 A CN 202010412632A CN 113663674 B CN113663674 B CN 113663674B
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compound
resin
catalyst
reaction
nitro compound
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CN113663674A (en
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饶先花
王贤文
黄华鹏
胡三友
杨思思
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Zhuhai Pairuier New Material Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/755—Nickel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/51—Spheres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
    • C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
    • C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
    • C07C213/02—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton by reactions involving the formation of amino groups from compounds containing hydroxy groups or etherified or esterified hydroxy groups
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

本发明公开了一种负载催化剂用多孔微球的制备方法，是通过无机材料与树脂热压成型后烧结得到的。微球为无机纳米多孔微球，微球坚固并且孔洞多，能够吸附大量催化剂。本发明同时公开了将本发明负载催化剂的多孔微球用于固定床反应器的催化加氢反应，应用于含硝基化合物的硝基还原反应，特别是还原含二硝基化合物、多硝基化合物，得到的氨基化合物纯度高、转化率高，催化剂的耐用性强，可以多次、长时间循环使用。The present invention discloses a method for preparing porous microspheres for supporting catalysts, which are obtained by hot pressing inorganic materials and resins and then sintering. The microspheres are inorganic nanoporous microspheres, which are strong and have many holes and can absorb a large amount of catalysts. The present invention also discloses that the porous microspheres supporting the catalyst of the present invention are used for catalytic hydrogenation reactions in fixed bed reactors, and are applied to nitro reduction reactions of nitro compounds, especially reduction of dinitro compounds and polynitro compounds. The obtained amino compounds have high purity and high conversion rate, and the catalyst has strong durability and can be recycled for multiple times and for a long time.

Description

Preparation method and application of porous microspheres and reduction method of nitro compound
Technical Field
The invention relates to the technical field of fine chemistry, in particular to a preparation method and application of a porous microsphere and a reduction method of a nitro compound.
Background
Typical amino compounds such as 4,4 diaminodiphenyl ether (ODA) are important organic chemical products, mainly for the synthesis of high performance polyimides. In the early industrial production, iron powder is usually adopted for catalytic reduction, but the yield is lower, the cost is higher, a large amount of iron mud and wastewater which are difficult to treat can be generated, and the environmental pollution is serious. Most of the current industrial production adopts catalytic hydrogenation reduction, but most of the current industrial production still adopts reaction kettle type intermittent catalytic hydrogenation reduction. Such as patent 201110330139.9. The intermittent process is complex to operate and has high production cost.
The fixed bed hydrogenation process is simpler in process and equipment structure, fluid flow can be regarded as ideal displacement flow, so that the chemical reaction rate is faster, and the required catalyst consumption and the reactor volume are smaller when the same production capacity is completed. However, the disadvantage is that no fine-grained catalyst can be used, the active inner surface of the catalyst being underutilized. To achieve a fixed bed continuous process, the catalyst must have high activity, high selectivity, high activity stability, and proper mechanical strength, wherein the activity and stability of the catalyst are key to determine whether the fixed bed process can be successfully implemented and industrial production can be performed.
Chinese patent application 2019105721199 discloses a method for continuously synthesizing 2-amino-2-methyl-1-propanol, wherein 2-nitro-2-methyl-1-propanol is adopted for catalytic reduction in a fixed bed reactor, and discharged and rectified after the reaction is finished to obtain high-purity 2-amino-2-methyl-1-propanol. However, the catalytic effect of the iron/aluminum catalyst adopted in the technical scheme is poor, and a catalyst with higher catalytic efficiency is needed. Such as porous microsphere loading, but the porous microsphere loading catalyst with high strength and high stability obtained by the prior art is expensive, and the development of the porous microsphere loading catalyst with high strength and high stability is required.
The existing fixed bed catalyst preparation method adopted in industry is complex in process and high in cost. Chinese patent application 201810080547.5 discloses a common preparation method of porous alumina microspheres, which comprises the steps of dissolving polyvinylpyrrolidone in absolute ethyl alcohol to obtain a dispersion alcohol solution, adding aluminum ammonium carbonate and sodium chloride into the dispersion alcohol solution, uniformly stirring to form a uniform suspension, placing the suspension into a reduced pressure distillation reaction kettle for reduced pressure distillation reaction for about 200min to obtain a viscous concentrated solution, adding the viscous concentrated solution into a mold, slowly heating until the ethanol is completely removed to obtain an alumina spherical precursor, placing the alumina spherical precursor into a muffle furnace for sintering, naturally cooling to obtain porous alumina spheres, finally placing the porous alumina spheres into deionized water for ultrasonic reaction for 3-4h, taking out and drying to obtain the porous alumina microspheres. The method is a commonly used alumina microsphere preparation method at the present stage, has low molding efficiency of a multipurpose die in the process steps, and is not environment-friendly due to large solvent volatilization. The prepared alumina microsphere has insufficient strength and is difficult to be applied to a fixed bed reactor.
Disclosure of Invention
The invention aims to provide a preparation method of porous microspheres, and the porous microspheres obtained by the preparation method have a plurality of holes and high strength, and can be used for catalytic application of fixed bed hydrogenation reduction. The invention also discloses a method for preparing the amino compound by using the porous microsphere fixed bed, which has high reaction conversion rate and high product purity.
The invention is realized by the following technical scheme:
A preparation method of the porous microsphere comprises the following steps of (1) mixing 20-60 parts of resin and 40-80 parts of inorganic material with 2-10 parts of auxiliary agent according to parts by weight, (2) grinding after uniformly mixing, hot-pressing the mixture into the microsphere at a temperature higher than the melting temperature of the resin, or adding a curing agent into the mixture to be cured into the microsphere in a mold, (3) sintering the mixture at a temperature higher than the decomposition temperature of the resin to obtain the porous microsphere, wherein the weight ratio of the resin to the inorganic material is (1:3) - (1:1), the resin is one or more selected from polystyrene, polyvinyl chloride, polyethylene, acrylic resin, polyurethane, epoxy resin, isocyanate and the like, the inorganic material is one or more selected from silicon carbide, silicon dioxide, titanium dioxide, aluminum nitride, aluminum oxide, silicon nitride, calcium fluoride, magnesium oxide, zinc oxide, zirconium oxide and the like, and the auxiliary agent is one or more selected from polyvinylpyrrolidone, polyethylene glycol and sodium dodecyl benzene sulfonate.
Preferably, step (2) employs hot pressing into microspheres at a temperature above the melting temperature of the resin after grinding. The porous microsphere obtained by adopting the preferred technology has higher strength and higher specific surface area.
Or curing in a mold by adding a curing agent, wherein the curing agent can be aliphatic amine curing agent.
The method comprises the steps of uniformly compounding resin, inorganic material and surfactant in solution, forming polymer/inorganic compound microspheres by adopting the resin and the inorganic material through a hot molding method, wherein the aim is that the inorganic material can form a discontinuous two-phase separation structure with the resin, and finally, removing the resin through a sintering method to form a continuous porous structure of the inorganic material. The ratio of the resin material to the inorganic material is 1:3-1:1. The pore size and the adsorption performance of the inorganic material can be regulated and controlled in the preparation process, so that the specific surface area is increased, and a better effect of adsorbing the catalyst is obtained.
The porous microsphere obtained by the preparation method is used for loading a catalyst, and can be specifically one or more of Pd (palladium) catalyst, ni (nickel) catalyst, ag (silver) catalyst, rh (rhodium) catalyst, ru (ruthenium) catalyst and Pt (platinum) catalyst.
The continuous pore structure imparts an excellent adsorption function thereto, and thus has a characteristic of being able to adsorb a metal catalyst substance. The porous microsphere is used for loading a catalyst, wherein the catalyst adsorption process can be one or a combination of a precipitation method, an impregnation method and a hydrothermal synthesis method, the active component is selected from one or a plurality of nitrate metal salt, acetate metal salt and metal ammonium salt, and the porous microsphere loaded active metal nanoparticle catalyst is obtained through reduction.
Specifically, the porous microspheres prepared by the method are immersed in a palladium chloride solution with the mass concentration of 8-15% for 1-3 hours, taken out and dried, and then reduced by NaBH 4, so that the supported Pd catalyst is obtained.
And the other porous microsphere is used for loading Ni (nickel) catalyst, the porous microsphere prepared by the method is immersed into a nickel nitrate solution with the concentration of 0.15-0.25mol/L for 2-5 hours, taken out and dried, reduced by formaldehyde aqueous solution, and dried to obtain the Ni-loaded catalyst.
The method for reducing the nitro of the nitro compound by using the supported catalyst comprises the following steps of adding the supported Pd catalyst, the nitro compound and a reaction solvent into a fixed bed reactor, carrying out reduction reaction under the hydrogen pressure of 40-100 ℃ and 1.5-5MPa, discharging hydrogen after the reaction of the raw material liquid with the space velocity of 0.02-0.3L/h is finished, filtering to obtain the amino compound and the reaction solvent, and then carrying out rectification technology to obtain the amino compound.
Specifically, the reaction solvent is selected from methanol, ethanol, dimethylformamide, dimethylacetamide and tetrahydrofuran, and the weight ratio of the reaction solvent to the nitro-containing compound is 1:1-10:1.
When the supported Ni catalyst is selected to replace the supported Pd catalyst, the reaction solvent is DMF, the reaction temperature is 110-160 ℃, the hydrogen pressure is 2.5-5MPa, and the space velocity of the raw material liquid is 0.02-0.3L/h.
The dinitro compound is at least one selected from dinitrotoluene, dinitrochlorobenzene, 4-dinitrodiphenyl ether, dinitrobenzene and bisphenol A dinitrodiphenyl ether, the mononitro compound is at least one selected from nitrobenzene and p-nitrophenol, and the polynitro compound is at least one selected from trinitrotoluene and trinitrophenol.
The invention has the following beneficial effects
The invention discloses a preparation method of porous microspheres, which is obtained by hot pressing and sintering resin and inorganic materials. Compared with the porous microsphere obtained by the prior art, the porous microsphere provided by the invention has the advantages of more surface holes and higher strength, and can meet the application of a fixed bed catalyst. The invention also discloses a method for catalytic reduction of the nitro-compound by the fixed bed, and the porous microsphere supported catalyst has high reaction conversion rate and high product purity and can be repeatedly used for a long time (300 hours).
The pore size of the porous microsphere can be adjusted, and the porous microsphere can be used for preparing different types of catalysts. The carrier microsphere has the advantages of high physical and chemical stability, large specific surface area, large adsorption capacity, good selectivity, low cost and the like, and has outstanding advantages when being applied to the preparation of the supported catalyst.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
The raw materials used in the invention are from commercial products:
4, 4-dinitrodiphenyl ether with the purity of 99.5 percent;
M-dinitrobenzene with purity of 99.5%;
Bisphenol A diether dinitro with purity of 99.5 percent
Polyethylene glycol with average molecular weight of 10000;
Polyethylene with average molecular weight of 150000;
epoxy resin with average molecular weight of 400;
Polyvinylpyrrolidone with an average molecular weight of 50000;
silica micropowder is 50 meshes;
Alumina micropowder 5 microns;
Titanium dioxide micropowder is 50nm;
A curing agent, namely an aliphatic amine curing agent;
self-made nickel nitrate solution with the concentration of 0.2 mol/L;
1mol/L chloroplatinic acid:
DMF is analytically pure;
THF, analytically pure;
The purity of the prepared product is tested by adopting gas chromatography.
Comparative example 1A:
weighing 10 g of polystyrene, dissolving in 30 ml of tetrahydrofuran, adding 10 g of silica micropowder and 0.5 g of polyvinylpyrrolidone, stirring uniformly, slowly adding into a coagulating bath formed by 100 ml of water, stirring to form microspheres, and filtering out the aqueous solution to form the polystyrene/silica composite microspheres. And then sintered in a high Wen Mafu furnace at 500 ℃ to obtain the porous silica/C composite.
The porous silica/C composite microsphere adsorption Pd catalyst is prepared by immersing the silica/C composite microsphere particles in a 10% palladium chloride solution for 2h, drying, and then reducing with NaBH 4, wherein Pd in the Pd/Al 2O3 catalyst accounts for 10% of the mass of the catalyst.
A fixed bed catalytic hydrogenation reduction process:
The prepared supported palladium catalyst is added into a fixed bed reactor, the solvent is methanol, the mass ratio of the methanol to the 4, 4-dinitrodiphenyl ether is 0.02L/h of the space velocity of a reaction solution of 2:1, the reaction temperature is 45 ℃, the reaction pressure is 3MPa, the pressure is reduced firstly after reduction, hydrogen is separated, the diaminodiphenyl ether and the methanol solvent are separated by adopting a continuous rectification process, the purity of the methanol and the high-purity diaminodiphenyl ether is 99.5% after gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 96%.
Comparative example 1B:
activity was used after 300 hours of cycling:
The reaction is continued for 300 hours in the fixed bed reactor, the solvent is methanol, the mass ratio of the methanol to the 4, 4-dinitrodiphenyl ether is 2:1, the space velocity of the reaction solution is 0.02L/h, the reaction temperature is 45 ℃, the reaction pressure is 3MPa, the pressure is reduced after the reduction, hydrogen is separated, the diaminodiphenyl ether and the methanol solvent are separated by adopting a continuous rectification process, the methanol and the high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 85% after gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 82%.
As is clear from comparative example 1A/B, the porous silica/C composite microsphere palladium catalyst obtained by the above method has low strength and is difficult to maintain for a long period of time and repeatedly use.
Example 1A:
Preparing porous alumina microspheres:
30 g of polyethylene and 60 g of alumina micropowder are added with 3 g of polyethylene glycol, uniformly mixed and ground, hot-pressed into microspheres at 180 ℃ in a die, and then the microspheres are sintered at 500 ℃ to form the porous microspheres of alumina. The prepared porous microspheres are immersed into a nickel nitrate solution with the concentration of 0.2mol/L for 4 hours, then dried, reduced by formaldehyde aqueous solution, and then dried, thus obtaining the alumina-supported Ni catalyst.
A fixed bed catalytic hydrogenation reduction process:
Adding the prepared supported Ni catalyst into a fixed bed reactor, wherein the mass ratio of the solvent DMF to the 4, 4-dinitrodiphenyl ether is 5:1, the hydrogen pressure is 3MPa, the reaction temperature is 120 ℃, the space velocity of the reaction solution is 0.03L/h, the pressure is reduced after the reaction is finished, hydrogen is separated, the diaminodiphenyl ether and DMF solvent adopt a continuous rectification process, DMF and high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 99.9% after gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 99.8%.
Example 1B:
activity was used after 300 hours of cycling:
Continuously reacting for 300 hours in the fixed bed reactor, wherein the solvent is DMF, the mass ratio of DMF to 4, 4-dinitrodiphenyl ether is 5:1, the hydrogen pressure is 3MPa, the reaction temperature is 120 ℃, the space velocity of the reaction solution is 0.2L/h, the pressure is reduced after the reaction is finished, hydrogen is separated, the diaminodiphenyl ether and DMF solvent are separated by adopting a continuous rectification process, the DMF and high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 99.9% by gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 99.5%.
The alumina porous microsphere Ni catalyst obtained by the preparation method of the porous microsphere has high strength, can be used for long-time and repeated catalysis, and completely meets the purpose of a fixed bed catalyst.
Example 2A:
Adding 1 g of fatty amine curing agent into 50 g of epoxy resin/50 g of titanium dioxide micropowder (weight ratio of 1:1), uniformly mixing, curing in a mold to form microspheres of epoxy resin/titanium dioxide, and sintering and curing the microspheres at high temperature of 600 ℃ to obtain porous microspheres of titanium dioxide. Immersing the microsphere into 1mol/L chloroplatinic acid solution for 2 hours, and adopting hydrazine hydrate for reduction to obtain the titanium dioxide catalyst loaded with platinum, wherein the platinum content is 2%.
Adding the prepared supported platinum catalyst into a fixed bed reactor, wherein the mass ratio of the solvent DMF to the 4, 4-dinitrodiphenyl ether is 2:1, the hydrogen pressure is 5MPa, the reaction temperature is 100 ℃, the space velocity of the reaction solution is 0.1L/h, the pressure is reduced after the reaction is finished, hydrogen is separated, the diaminodiphenyl ether and DMF solvent are separated by adopting a continuous rectification process, the DMF and high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 99.9% by gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 100%.
Example 2B:
activity was used after 300 hours of cycling:
and continuing the reaction in the fixed bed reactor for 300 hours, wherein the solvent is DMF, the mass ratio of DMF to 4, 4-dinitrodiphenyl ether is 2:1, the hydrogen pressure is 5MPa, the reaction temperature is 100 ℃, the space velocity of the reaction solution is 0.05L/h, the pressure is reduced after the reaction is finished, hydrogen is separated, the diaminodiphenyl ether and DMF solvent are subjected to continuous rectification, DMF and high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 99.8% after gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 99.8%.
The titanium dioxide porous microsphere platinum catalyst obtained by the preparation method of the porous microsphere has high strength, can be used for long-time and repeated catalysis, and completely meets the purpose of a fixed bed catalyst.
Example 3A:
Adding 3 g of sodium dodecyl benzene sulfonate into 50 g of epoxy resin/100 g of aluminum oxide (weight ratio of 1:2) micropowder, adding an aliphatic amine curing agent, uniformly mixing, curing in a mold to form microspheres of the epoxy resin/aluminum oxide, and sintering and curing the microspheres at a high temperature of 600 ℃ to obtain porous microspheres of the aluminum oxide. Immersing the microsphere into 1mol/L chloroplatinic acid solution for 6 hours, and adopting hydrazine hydrate for reduction to obtain the alumina catalyst loaded with platinum, wherein the platinum content is 2%.
Adding the prepared supported platinum catalyst into a fixed bed reactor, wherein the solvent is DMF, the mass ratio of DMF to bisphenol A dinitrodiphenyl ether is 2:1, the hydrogen pressure is 5MPa, the reaction temperature is 100 ℃, the space velocity of the reaction solution is 0.1L/h, the pressure is reduced after the reaction is finished, hydrogen is separated, the bisphenol A diaminodiphenyl ether and DMF solvent adopt a continuous rectification process, DMF and high-purity bisphenol A diaminodiphenyl ether are separated, the purity of bisphenol A diaminodiphenyl ether is 98.5% after gas chromatography analysis, and the conversion rate of bisphenol A dinitrodiphenyl ether is 100%.
Example 3B:
activity was used after 300 hours of cycle:
continuously reacting for 300 hours in the fixed bed reactor, wherein the solvent is DMF, the mass ratio of DMF to bisphenol A dinitrodiphenyl ether is 2:1, the hydrogen pressure is 5MPa, the reaction temperature is 100 ℃, the reaction pressure is 5MPa, the space velocity of the reaction solution is 0.1L/h, after the reaction is finished, the pressure is reduced, the hydrogen is separated, the bisphenol A diaminodiphenyl ether and DMF solvent are subjected to continuous rectification process, the DMF and the high-purity bisphenol A diaminodiphenyl ether are separated, the purity of the bisphenol A diaminodiphenyl ether is 99.7% after gas chromatography analysis, and the conversion rate of the bisphenol A dinitrodiphenyl ether is 100%.
The alumina porous microsphere platinum catalyst obtained by the preparation method of the porous microsphere has high strength, can be used for long-time and repeated catalysis, and completely meets the purpose of a fixed bed catalyst.
Example 4A:
50g of isocyanate/50 g of alumina micropowder are uniformly mixed, polyether polyol equivalent to the isocyanate is added, and the mixture is cured in a mold to form polyurethane/alumina microsphere, and the microsphere is sintered and cured at a high temperature of 600 ℃ to obtain the alumina porous microsphere. Immersing the microsphere into 1mol/L chloroplatinic acid solution for 4 hours, and adopting hydrazine hydrate for reduction to obtain the alumina catalyst loaded with platinum, wherein the platinum content is 2%.
The prepared supported platinum catalyst is added into a fixed bed reactor, the solvent is DMAc, the mass ratio of DMAc to m-dinitrobenzene is 2:1, the hydrogen pressure is 3MPa, the reaction temperature is 100 ℃, the reaction is finished, the pressure is reduced, hydrogen is separated, m-phenylenediamine and DMF solvent are subjected to continuous rectification process, DMF and high-purity m-phenylenediamine are separated, the purity of the m-phenylenediamine is 99.9% after gas chromatography analysis, and the conversion rate of m-dinitrobenzene is 100%.
Example 4B:
activity was used after 300 hours of cycling:
The reaction is continued for 300 hours in the fixed bed reactor, the solvent is DMAc, the mass ratio of DMAc to m-dinitrobenzene is 2:1, the hydrogen pressure is 3MPa, the reaction temperature is 100 ℃, the pressure is reduced firstly after the reaction is finished, hydrogen is separated, m-phenylenediamine and DMF solvent are subjected to continuous rectification process, DMF and high-purity m-phenylenediamine are separated, the purity of the m-phenylenediamine is 99.9% after gas chromatography analysis, and the conversion rate of m-dinitrobenzene is 99.8%.
The alumina porous microsphere platinum catalyst obtained by the preparation method of the porous microsphere has high strength, can be used for long-time and repeated catalysis, and completely meets the purpose of a fixed bed catalyst.
Example 5A:
Preparing porous alumina microspheres:
30g of polyvinyl chloride and 60 g of alumina micropowder are added with 3 g of polyethylene glycol, uniformly mixed and ground, hot-pressed into microspheres at 180 ℃, and then the microspheres are sintered at 500 ℃ to form the porous microspheres of alumina. Immersing in 0.2mol/L palladium chloride solution for 4 hours, drying, reducing with formaldehyde aqueous solution, and drying to obtain the palladium catalyst loaded by alumina.
A fixed bed catalytic hydrogenation reduction process:
Adding the prepared supported Pd catalyst into a fixed bed reactor, wherein the mass ratio of the solvent DMF to the 4, 4-dinitrodiphenyl ether is 2:1, the hydrogen pressure is 3MPa, the reaction temperature is 120 ℃, the reaction pressure is 3MPa, after the reaction is finished, the pressure is reduced, hydrogen is separated, the diaminodiphenyl ether and DMF solvent are subjected to continuous rectification process, ethanol and high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 99.9% after gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 99.8%.
Example 5B:
activity was used after 300 hours of cycling:
The reaction is continued for 300 hours in the fixed bed reactor, the solvent is DMF, the mass ratio of DMF and 4, 4-dinitrodiphenyl ether is 2:1, the reaction temperature is 120 ℃, the reaction pressure is 3MPa, the crude diaminodiphenyl ether is decompressed firstly, hydrogen is separated, the diaminodiphenyl ether and DMF solvent are subjected to continuous rectification process, ethanol and high-purity diaminodiphenyl ether are separated, the purity of the diaminodiphenyl ether is 99.9% after gas chromatography analysis, and the conversion rate of the 4, 4-dinitrodiphenyl ether is 99.5%.
The porous microsphere Pd catalyst of alumina obtained by the preparation method of the porous microsphere has high strength, can be used for long-time and repeated catalysis, and completely meets the purpose of a fixed bed catalyst.

Claims (9)

1. A reduction method of nitro compound is characterized in that Pd-loaded catalyst, nitro compound and reaction solvent are added into a fixed bed reactor, reduction reaction is carried out under the hydrogen pressure of 40-100 ℃ and 1.5-5MPa, hydrogen is discharged after the reaction is finished, a mixture of amino compound and reaction solvent is obtained by filtration, and then rectification process is carried out to obtain amino compound;
The preparation method of the supported Pd catalyst comprises the steps of immersing porous microspheres in a palladium chloride solution with the mass concentration of 8-15% for 1-6 hours, taking out and drying, and reducing by NaBH 4 to obtain the supported Pd catalyst;
The preparation method of the porous microsphere comprises the following steps of (1) mixing 20-60 parts of resin and 40-80 parts of inorganic material with 2-10 parts of auxiliary agent according to parts by weight, (2) grinding after mixing uniformly, hot-pressing the mixture into the microsphere at a temperature higher than the melting temperature of the resin, and (3) sintering the mixture at a temperature higher than the decomposition temperature of the resin to obtain the porous microsphere, wherein the weight ratio of the resin to the inorganic material is (1:3) - (1:1), the resin is one of polystyrene, polyvinyl chloride, polyethylene, acrylic resin, polyurethane and epoxy resin, the inorganic material is one or more of silicon carbide, silicon dioxide, titanium dioxide, aluminum nitride, aluminum oxide, silicon nitride, calcium fluoride, magnesium oxide, zinc oxide and zirconium oxide, and the auxiliary agent is one or more of polyvinylpyrrolidone, polyethylene glycol and sodium dodecyl benzene sulfonate.
2. The method for reducing a nitro compound according to claim 1, wherein the reaction solvent is one or more selected from methanol, ethanol, dimethylformamide, dimethylacetamide and tetrahydrofuran, and the weight ratio of the reaction solvent to the nitro compound is 1:1-10:1.
3. The method for reducing a nitro compound according to claim 1, wherein the nitro compound is at least one selected from the group consisting of a mononitro compound and a polynitro compound.
4. The method for reducing a nitro compound according to claim 3, wherein the polynitro compound is selected from the group consisting of dinitrotoluene, dinitrochlorobenzene, 4-dinitrodiphenyl ether, dinitrobenzene, and bisphenol A dinitrodiphenyl ether, and the mononitro compound is selected from the group consisting of nitrobenzene and p-nitrophenol.
5. The method for reducing a nitro compound according to claim 3, wherein the polynitro compound is at least one selected from trinitrotoluene and trinitrophenol.
6. A reduction method of nitro compound is characterized in that a supported Ni catalyst, dimethylformamide and nitro compound are added into a fixed bed reactor, then the reduction reaction is carried out under the hydrogen pressure of 2.5-5MPa at the reaction temperature of 110-160 ℃, the hydrogen is discharged after the reaction is finished, the mixture of amino compound and reaction solvent is obtained by filtration, and then the amino compound is obtained by rectification process;
The preparation method of the supported Ni catalyst comprises the steps of immersing porous microspheres in 0.15-0.25mol/L nickel nitrate solution for 1-6 hours, taking out and drying, reducing with formaldehyde aqueous solution, and drying to obtain the supported Ni catalyst;
The preparation method of the porous microsphere comprises the following steps of (1) mixing 20-60 parts of resin and 40-80 parts of inorganic material with 2-10 parts of auxiliary agent according to parts by weight, (2) grinding after mixing uniformly, hot-pressing the mixture into the microsphere at a temperature higher than the melting temperature of the resin, and (3) sintering the mixture at a temperature higher than the decomposition temperature of the resin to obtain the porous microsphere, wherein the weight ratio of the resin to the inorganic material is (1:3) - (1:1), the resin is one of polystyrene, polyvinyl chloride, polyethylene, acrylic resin, polyurethane and epoxy resin, the inorganic material is one or more of silicon carbide, silicon dioxide, titanium dioxide, aluminum nitride, aluminum oxide, silicon nitride, calcium fluoride, magnesium oxide, zinc oxide and zirconium oxide, and the auxiliary agent is one or more of polyvinylpyrrolidone, polyethylene glycol and sodium dodecyl benzene sulfonate.
7. The method for reducing a nitro compound according to claim 6, wherein the nitro compound is at least one selected from the group consisting of a mononitro compound and a polynitro compound.
8. The method for reducing a nitro compound according to claim 7, wherein the polynitro compound is selected from the group consisting of dinitrotoluene, dinitrochlorobenzene, 4-dinitrodiphenyl ether, dinitrobenzene, and bisphenol A dinitrodiphenyl ether, and the mononitro compound is selected from the group consisting of nitrobenzene and p-nitrophenol.
9. The method for reducing a nitro compound according to claim 7, wherein the polynitro compound is at least one selected from trinitrotoluene and trinitrophenol.
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