CN117042873A - Catalytic element with regular cellular structure for heterogeneous reactions - Google Patents

Abstract

The present invention relates to a catalytic element having a regular honeycomb structure for heterogeneous reactions. A catalytic element for heterogeneous reactions involving deep oxidation of hydrocarbons and carbon monoxide is described, said catalytic element being made of a catalytically active substance containing active ingredients and aluminum oxide and having a regular honeycomb structure and rectangular honeycomb channels. block form. The alumina precursor used is a mixture of aluminum compounds and alumina powder with the formula Al ₂ O ₃ ·nH ₂ O where 0.3≤n≤1.5 obtained by rapid partial dehydration of gibbsite, in a ratio of 20‑80wt % Al ₂ O ₃ ·nH ₂ O where 0.3≤n≤1.5 and 80‑20wt% alumina powder, the channel walls have open transport pores with size 50‑500nm, said open transport pores accounting for 35% of the total pore volume -70%, and the active ingredient includes a metal or metal compound selected from the group of manganese, chromium, copper, iron, or a mixture thereof. The object of the present invention is to develop catalytic elements in the form of blocks with a regular honeycomb structure, which exhibit high thermal stability and mechanical strength while also having high activity.

Description

Catalytic element with regular honeycomb structure for heterogeneous reactions

Technical Field

The present invention relates to a catalyst with a regular honeycomb structure for heterogeneous reactions, for example, for industrial waste gas treatment, selective reduction of nitrogen oxides and oxygen, ozone destruction, and a process for fixed-bed catalytic dehydrogenation of lower alkanes, alkenes, and aromatic alkanes to produce corresponding alkenes, chain dienes, and aromatic alkenes.

Background Art

The catalyst operating conditions are characterized by very high temperatures and mechanical loads, excessive exposure to gas streams. For example, the temperature range for industrial waste gas reduction by secondary combustion is from 400 to 1000 ° C, which determines the requirements for high thermal stability of the catalyst. The operating environment of the catalyst also involves high mechanical loads and excessive exposure to gas streams. Therefore, the catalyst performance and life depend on its ability to maintain its strength, phase composition uniformity and high activity in long-term severe operation. If bulk catalysts in the form of spherical or cylindrical pellets are used under such conditions, high bed resistance, uneven temperature distribution over the reactor cross section and enhanced particle attrition are usually recorded.

For the purpose of eliminating the above disadvantages, monolithic (honeycomb) catalysts can be used, in which a support as a solid monolith is used. Typically, the monolith has a large number of parallel non-intersecting channels and is made of a silicate ceramic material. The channel surface is coated with active components.

The honeycomb catalyst should have high mechanical strength, thermal stability and good flow rate in each layer of the channel wall, and have a sufficiently high channel density so that the reagents can enter the internal channel wall to increase the active surface area and corresponding activity of the honeycomb monolithic catalyst (monolithic catalyst).

Honeycomb monolithic catalysts can consist of active components mixed with a binder (so-called complete monoliths), or be present as a support coated with active components. In terms of the distribution of the active components, there are catalysts in which the active components are located on the outer surface of the monolith, or are evenly distributed over the wall depth (R. Avila, M. Montes, E. E. Miro, Chem. Eng. Journal 109 (2005), 11-36).

There is a known method for producing a honeycomb catalyst for a heterogeneous catalytic reaction system (RU 2724261, IPCB01D 53/94; B01D 53/56; B01D 53/58; B01J 29/064; B01J29/068; B01J 29/072; B01J 29/076; B01J 29/46; B01J 29/56; B01J 29/72, published on June 22, 2020), in which the active component is applied to a carrier (inert support) or the active component (catalyst) is mixed with other components to produce a catalyst for the selective catalytic reduction of nitrogen oxides (SCR).

According to a second variant, the catalyst is mixed with other components such as fillers, binders and reinforcing agents to obtain an extrudable paste which is further extruded through a die to form a honeycomb monolith.

Developing more durable coatings for honeycomb supports is one of the existing trends, but its production technology is complicated, which limits the widespread application of honeycomb catalysts in different heterogeneous high-temperature reactions.

There is a known catalyst for ozone destruction process (patents KR 900003136, IPC B01D53/34; B01J 23/34; B01J 37/00, published on September 18, 1989), which comprises a support having a honeycomb structure; a material of _SiO2 (30 _% ), _Al2O3 (35%), CaO (3%), MgO (1%), monazite (5%), _TiO2 (25.5%) and Ag (0.5%) is prepared and calcined at 150-250°C to form a ceramic support. The obtained support is doped with _MnO2 .

To support the active components, cordierite honeycomb monoliths may be used.

There is a known catalyst for removing organic compounds (patent US2020197912, IPC B01D 53/86; B01J 23/42; B0U 23/44, published on June 25, 2020). The catalyst includes cordierite honeycomb ceramics and uses a mixture of platinum and palladium as an active component; the amount of the mixture of platinum and palladium ranges from 0.01% to 0.05% of the mass of the substrate; the amount of the carrier ranges from 3% to 5% of the mass of the substrate.

A disadvantage is the use of precious metals, which limits their application and is cost-ineffective in some cases.

There are known catalysts for removing volatile organic compounds (VOCs) (patents CN110404550, IPCB01D 53/44; B01D 53/86; B01J 23/83, published on November 05, 2019). The catalyst for removing volatile organic compounds includes a carrier and a coating material applied to the carrier, wherein the carrier is a monolithic carrier having a cordierite honeycomb, and the coating material includes a composite Co/Ce-Zr-M oxide, wherein M is one or more of La, Nd, Рr and Y. The catalyst does not include expensive precious metal components.

The main disadvantage of the above analogs is their low thermal stability, which leads to cracking and peeling of the active catalytic layer from the support, which in turn leads to clogging of the honeycomb channels, and if dusty gases are processed, these processes are accelerated several times due to erosion.

The closest technical solution to the claimed technical solution in terms of structure and monolithic shape is a catalyst with a regular honeycomb structure for heterogeneous high-temperature reactions (patents RU 2209117, IPC B01J 35/04; B01J23/745; B01J 23/26; B01J 21/04; С01V21/26, published on July 27, 2003), manufactured as a single monolith 25 to 50 mm high, with a square cross-section with a side length of 65 to 73 mm. A regular honeycomb structure with channel dimensions of 4x4 mm, 5x5 mm is arranged in the monolith, using walls with a thickness of 0.8 to 1.5 mm.

The closest technical solution to the claimed technical solution in terms of the method for producing the claimed catalyst with a regular honeycomb structure is a method for producing a honeycomb monolith as a parallelepiped or hexagonal prism comprising oxides of iron and aluminum and a promoter (patents RU 2207904, IPC B01J 23/84; B01J 21/04; С01V21/26, published on July 10, 2003). As a promoter, the catalyst comprises at least one compound of an element from the following group: Co, Mn, Cr, V, Mo, Sn, Bi or a mixture thereof, and a precursor of aluminum oxide that is an aluminum compound of the formula Al ₂ O ₃ ·nH ₂ O, where 0.3≤n≤1.5, having a layered X-ray amorphous structure. The precursor of aluminum oxide may comprise at least one compound of an element from the following group: Si, Mg, Sa, in an amount expressed as an oxide not exceeding 1.0 wt.%. The obtained catalyst has the following composition, in wt. %: Fe ₂ O ₃ -65 to 86, promoter as oxide -0.1 to 15, the rest is Al ₂ O _3. The honeycomb catalyst further comprises titanium oxide in an amount not exceeding 5 wt. %.

Patent RU 2207904 proposes a method for producing honeycomb monoliths from catalytically active substances.

To produce the monolith, a mixture of active components and peptized aluminum hydroxide is prepared based on an X-ray amorphous compound of formula Al ₂ O ₃ ·nH ₂ O (where 0.3≤n≤1.5). From the paste obtained, monoliths as parallelepipeds or hexagonal prisms are produced by extrusion through a die (mold). The honeycomb monolith is air-dried at room temperature for 6 days and dried in a flow dryer, with air heated to 350° C. flowing through the honeycomb channels. Once dried, the catalyst monolith is calcined at 950° C.

According to these solutions, the honeycomb structure of the proposed catalyst has geometric components: channels and channel walls.

In long channels with small channel cross-sections, there is always a risk of clogging the channels with reagents and reaction products or soot. The flow within the channel is different along the channel axis and in the wall layers, there is no filtration through the channel walls, which ultimately reduces the accessibility of active sites on the channel walls and reduces the activity and lifetime of the catalyst.

In an extruded catalyst having a honeycomb structure, in which the working mixture to be shaped is a catalytically active mixture, the active components are distributed over the entire volume of the catalyst as a monolithic mass of a regular honeycomb structure having honeycomb channels.

However, modifications of the composition of the working mixture and the catalytically active components lead to molding difficulties or to cracking of the monolith, which makes the development of improved catalysts with a honeycomb structure cost-intensive and expensive even for one process, but especially for different chemical processes.

Summary of the invention

The object of the present invention is to develop catalysts for heterogeneous reactions as honeycomb monoliths from catalytically active substances, which monoliths exhibit high thermal stability, mechanical strength and maintain high activity, and to develop a simple method for producing them, which method allows to significantly expand the use of honeycomb monolithic catalysts in different chemical processes.

The problem is solved by using a catalyst for heterogeneous reactions including deep oxidation of hydrocarbons and carbon monoxide, made of a catalytically active mass comprising an active component, aluminum oxide, in a honeycomb monolith with rectangular honeycomb channels. As a precursor of aluminum oxide, a mixture of an aluminum compound of formula _Al2O3 · _nH2O (wherein 0.3≤n≤1.5) obtained by rapid partial dehydration of gibbsite and aluminum oxide powder is used, the ratio being 20 to 80 wt.% of _Al2O3 · _nH2O (wherein 0.3≤n≤1.5) and 80 to 20 _wt .% of aluminum oxide powder, wherein the channel walls have open transport pores with a size of 50 to 500 nm, said open transport pores accounting for 35 to 70% of the total pore volume, and the active component comprises a _metal or a compound of a metal selected from the group of manganese, chromium, copper, iron or a mixture thereof.

Preferably, the particle size of the active ingredient is no greater than 20 to 50 nm.

Preferably, the rectangular monolithic substrate has a side of 20 to 150 mm, a height of 30 to 1470 mm, a channel wall thickness of 0.1 to 2 mm, a channel side dimension of 0.1 to 19.9 mm, and the number of channels per square inch of the monolithic cross section is 1.5 to 250 cpsi.

Preferably, the honeycomb monolith is formed as a right hexagonal prism or a right rectangular prism, and the inner walls of all honeycomb channels have the same thickness.

Preferably, a groove is made on the outer side of the honeycomb block, and the groove has a depth equal to 1/2 of the side of the honeycomb channel.

Preferably, the catalyst comprises a metal or a metal compound selected from metal oxides, metal hydroxides, metal carbonates, metal hydroxycarbonates or mixtures thereof.

Preferably, the metal or the metal compound comprises one or more metals selected from Na, K, Ba, Al, Si, V, Co, Ni, Zn, Mo, Ag, Sn, La and Ce.

Preferably, the catalyst comprises titanium dioxide, zirconium dioxide, metal aluminates or mixtures thereof.

Preferably, the catalyst has a specific surface area of 1 to 100 m ² /g, a bulk density of 0.4 to 1.4 g/cm ³ , a mechanical strength of not less than 6.0 MPa, and a bed flow resistance of not more than 280 Pa/m at a flow rate of 0.5 m/s.

The problem is also solved by a method for producing the above-mentioned catalyst for heterogeneous reactions involving deep oxidation of hydrocarbons and carbon monoxide, comprising the steps of preparing a powder material from the components of the catalytically active substance, mixing it with a binder based on an aluminum compound, a plasticizing additive, a pore structuring additive including a combustible pore structuring additive to obtain a catalytically active substance, shaping it by extrusion through a die to produce a shaped element as a honeycomb monolith with rectangular honeycomb channels, air drying, drying and calcining. For shaping, a mixture of a binder of an aluminum compound of the formula _Al2O3 · _nH2O wherein 0.3≤n≤1.5 obtained by rapid partial dehydration of gibbsite and aluminum oxide powder is used, the ratio of the aluminum compound of the formula _Al2O3 · _nH2O wherein _{0.3≤n≤1.5} and the aluminum oxide powder being 20 to 80 wt.%, wherein the channel walls have open transport pores having a size of 50 to 500 nm, and the open transport pores occupy ₃₅ to 70% of the total pore volume, wherein the mixture is preliminarily activated by combined grinding or single grinding, mixed with a component of a catalytically active substance comprising a metal or a compound of a metal selected from the group of manganese, chromium, copper, iron or a mixture thereof, a plasticizing additive and a pore structuring additive, the catalytically active substance obtained is plasticized, shaped, air-dried, then dried at a gradually increasing temperature from 40 to 120°C, and calcined at a temperature of 300 to 1200°C for 1 to 16 hours.

Preferably, the aluminum compound of the formula Al ₂ O ₃ .nH ₂ O wherein 0.3≤n≤1.5 has an average particle size of 30 μm after activation by grinding.

Preferably, pyrolusite and/or ramsdellite preliminarily ground in a pulverizer to a particle size of not more than 40 μm is used as the manganese compound.

Preferably, polyvinyl alcohol or isopropanol, polyethylene glycol, cellulose, starch, urotropin, sawdust, stearic acid and/or commercially available derivatives thereof or mixtures thereof are used as plasticizing additives in an amount of 0.1 to 15.6 wt.%.

Preferably, nitric acid having an acid modulus of 0.10 to 0.30 is used for plasticizing the catalyst working mixture.

Preferably, the shaped monolith is air-dried at a temperature of 18 to 20° C. and a relative humidity of 20 to 90% for 7 to 14 days.

Preferably, the monolith is dried at a relative humidity of 20 to 90% for a period of 7 to 21 days.

Preferably, calcination is performed at a temperature of 350 to 500° C. for 2 to 8 hours.

Preferably, low temperature calcination is carried out at a temperature of 400 to 600°C for not less than 1 to 6 hours, followed by high temperature calcination at a temperature of 900 to 980°C for not less than 1 to 6 hours, and optionally the temperature is subsequently increased to 1200°C.

Preferably, the strength is not less than 4.0 MPa after 100 to 200 heating cycles in a muffle furnace in air from room temperature to 800°C and cooling to room temperature.

The problem is also solved by a catalytic process comprising deep oxidation of hydrocarbons and carbon monoxide using the above-mentioned catalyst produced by the above-mentioned method, the catalytic process comprising the step of contacting a reaction mixture with the catalyst under catalytic reaction conditions.

The proposed catalyst for heterogeneous reactions has the following substantial differences from known solutions:

- as precursor of aluminum oxide, a mixture of an aluminum compound of formula _Al2O3 · _nH2O (wherein 0.3≤n≤1.5) obtained by rapid partial dehydration of gibbsite and aluminum oxide powder is used, the ratio being 20 to ₈₀ wt.% of _Al2O3 · _nH2O (wherein 0.3≤n≤1.5) and 80 to 20 wt.% of aluminum oxide powder _;

- The channel walls have open transport pores with a size of 50 to 500 nm, which account for no less than 35% of the total pore volume.

The proposed set of features allows the production of catalysts for heterogeneous reactions from catalytically active substances as honeycomb monoliths with rectangular honeycomb channels, with high thermal stability and mechanical strength and maintaining high activity.

The technical result of the proposed solution is the development of a catalyst as a honeycomb monolith for heterogeneous reactions from catalytically active substances, which has high thermal stability, mechanical strength and maintains high activity, as well as the development of a simple method for its production, which allows to significantly expand the use of honeycomb monolithic catalysts in different chemical processes.

In this case, the problem of using catalysts in high-production rate plants and dusty mixtures is solved, and the high ratio of contact surface to element volume allows efficient heterogeneous reactions at low (100 to 1500 ppm) and very low (<100 ppm) reagent concentrations.

The proposed method for producing the catalyst as a honeycomb monolith is as follows:

As aluminum compound of formula _{Al2O3 · nH2O} for preparing the catalyst, _a layered X-ray amorphous aluminum compound of formula _Al2O3 · _nH2O (wherein 0.3≤n≤1.5) is used. The compound _Al2O3 · _nH2O , wherein 0.3≤n≤1.5, is obtainable by rapid partial dehydration of gibbsite by any known method, for _example according to patent RU 2064435 (IPC C01F 7/44, published on July 27, 1996) or according to patent RU 2148017 (IPC C01F 7/44, published on April 27, 2000).

The compound _Al2O3 · _nH2O of layered X-ray amorphous structure, wherein 0.3≤n≤1.5, means a compound for which no characteristic lines of any crystalline phase can _be detected by X-ray analysis. The compound has an increased reactivity, which allows the compound of the catalyst component to be inserted into the interlayer space between the aluminum hydroxide packages, accompanied by the sliding of the aluminum hydroxide packages relative to each other.

During the production of the catalyst, as the temperature rises to 350 to 1200° C., an active phase is formed on the aluminum compound of the formula Al ₂ O ₃ ·nH ₂ O with a layered X-ray amorphous structure, where 0.3≤n≤1.5, in the presence of compounds of the following metals: Na, K, Ba, Al, Si, V, Cr, Mn, Fe, Со, Ni, Cu, Zn, Mo, Ag, Sn, La and Се. At the same time, the layered X-ray amorphous structure of the aluminum compound of the formula Al ₂ O ₃ ·nH ₂ O, where 0.3≤n≤1.5, helps to produce highly dispersed active components, which increases the mechanical strength of the catalyst due to the formation of stronger bonds between the active component particles and the aluminum oxide surface.

A binder of formula _Al2O3 · _nH2O (hereinafter referred to as thermally activated alumina, TAA) and alumina powder are preliminarily activated by grinding (disintegration) in combination or separately to a specific particle size, possibly an aluminum compound of formula _{Al2O3 ·nH2O ,} where 0.3≤n≤1.5, having an average particle size of 30 μm after _activation by grinding.

As alumina powder different phases can be used: γ-Al ₂ O ₃ , χ-Al ₂ O ₃ , α-Al ₂ O ₃ , which are also ground to a specific particle size in a pulverizer.

As plasticizing additives, polyvinyl alcohol or isopropanol, polyethylene glycol, cellulose, starch, hexamethylenetetramine, sawdust, stearic acid and/or commercially available derivatives thereof or mixtures thereof are used in amounts of 0.1 to 15.6 wt.%.

Nitric acid having a sour modulus of 0.10 to 0.30 was used for plasticizing the catalyst working mixture.

In order to plasticize the catalytically active substance, water can be added and, in addition to nitric acid, other acids can also be used.

The prepared catalytically active substance (working mixture) is shaped by extrusion through a die to produce a shaped element as a honeycomb monolith having rectangular honeycomb channels, the monolith having the following dimensions: the side of the rectangular block substrate is 20 to 150 mm, the height is 30 to 1470 mm, the channel wall thickness is 0.1 to 2 mm, the size of the channel side is 0.1 to 19.9 mm, and the number of channels per square inch of the monolith cross section is 1.5 to 250 cpsi.

The honeycomb monolith has the shape of a right hexagonal prism ( FIG. 2 ) or a right rectangular prism.

Grooves are made on the outside of the honeycomb monolith, with a depth equal to 1/2 of the sides of the honeycomb channels. When the monoliths are stacked in layers, the grooves form additional channels (Figure 3).

The catalyst may include, as an active component, a metal or a compound of a metal selected from metal oxides, metal hydroxides, metal carbonates, metal hydroxycarbonates or mixtures thereof.

Depending on the catalytic process, at least one metal or metal compound is selected from the group of Na, K, Ba, Al, Si, V, Co, Ni, Zn, Mo, Ag, Sn, La and Ce.

The catalyst may include titanium dioxide, zirconium dioxide, metal aluminates, or mixtures thereof.

For ozone destruction, the catalyst may include, as an active component, an oxide of at least one metal selected from the group consisting of copper, manganese, cobalt and nickel.

For the selective catalytic reduction of nitrogen oxides, the catalyst may comprise oxides of vanadium, cerium and manganese as active components.

The shaped workpiece is possibly air-dried for 7 to 14 days under the following conditions: at a temperature of 18 to 20° C. and a relative humidity of 20 to 90%.

The monolith is then dried at a temperature of 40 to 120°C and a relative humidity of 20 to 90% for 7 to 21 days and then calcined, including low temperature calcination which may be performed at a temperature of 350 to 500°C for 2 to 8 hours.

Possibly, low temperature calcination is carried out at a temperature of 400 to 600°C for not less than 1 to 6 hours, followed by high temperature calcination at a temperature of 900 to 980°C for not less than 1 to 6 hours, optionally followed by raising the temperature to 1200°C.

The calcination temperature depends on the metal compound:

Cu – 400 to 600 °C;

Mn – 400 to 1000°C;

Cr – 400 to 700°C;

Fe – 400 to 850°C.

The temperature was gradually increased at a rate of 1 to 5°C per minute.

High temperature calcination may be performed at a temperature of 900 to 980°C for not less than 1 to 6 hours, optionally followed by raising the temperature to 1200°C.

The catalyst obtained after calcination has a specific surface area of 1 to 100 ^m2 /g, a bulk density of 0.4 to 1.4 g/ ^cm3 , a mechanical strength of not less than 6.0 MPa, a liquid flow resistance of the bed at a flow rate of 0.5 m/s of not more than 280 Pa/m, a strength of not less than 4.0 MPa after 100 to 200 heating cycles in a muffle furnace in air from room temperature to 800°C and cooling to room temperature, and a particle size of the active component of not more than 20 to 50 nm.

The proposed solution allows the development of catalysts made into honeycomb monoliths, providing an optimal combination of strength and minimum flow resistance of the catalyst bed in high-speed gas streams, ensuring high performance and reduced economic costs in the final application, for example, gas treatment.

Preferred Embodiments of the Invention

The process described below for preparing a catalyst for deep oxidation of organic compounds includes preparation steps that are also useful for producing catalysts for other heterogeneous reactions, such as ozone destruction, dehydrogenation of ethylbenzene to styrene, selective catalytic reduction of nitrogen oxides, selective partial oxidation of organic compounds.

The strength was measured using an instrument for measuring mechanical strength, MP-9S.

The catalytic activity of the samples prepared according to Examples 1 to 5 was determined by the flow circulation method in a model reactor for deep oxidation of butane. The butane concentration in the reaction mixture was 0.2 vol.%, the catalyst sample weight was 1±0.2 g. The butane oxidation reaction rate (cm ³ /g·s) at a temperature of 400±2° C. with 60% butane conversion was used as an activity measure.

The composition and physical and chemical characteristics of the resulting catalysts were determined as follows:

The catalyst density is determined by dividing the mass of the monolithic catalyst by the geometric volume.

The contents of the components in the catalyst samples were determined by X-ray fluorescence using a "Spectroscan MAX-GV" instrument.

The specific surface area of the sample was measured by argon thermal desorption method using a gas meter GKh-1.

The flow resistance of the catalyst pellet bed is determined in a fixed catalyst bed on a pressure drop test bench.

The porous structure of the prepared samples was studied by mercury intrusion porosimetry using an Autopore 9500 mercury intrusion porosimeter.

The examples provided below disclose the proposed solution.

Example 1

A catalyst for deep oxidation of organic compounds was prepared as a honeycomb monolith with rectangular honeycomb channels.

The catalytically active material (working mixture) is prepared by mixing the required amounts of binders - aluminum hydroxide powder, aluminum oxide powder, manganese (IV) oxide powder and organic additives (e.g. sawdust) in a rotor mixer for 10 to 120 min and then in a mixer with Z-blades for 5 to 45 min.

As aluminum hydroxide, a product of rapid partial dehydration of gibbsite is used, having the formula _{Al2O3 ·nH2O ,} wherein n=0.9 (TAA), comprising not less than 40 wt.% of shaped boehmite, ground and having an average particle size of 30 μm, a specific surface area of about 250 ^m2 /g, a loss on drying (LOD) of not more than 18%, and a loss on ignition ( ^LOI800 ) of 28 to 32%.

As alumina, precalcined highly dispersed γ-Al ₂ O ₃ (the weight content of the 40 μm fraction is not less than 60%) is used.

The amount of TAA was 80 wt.%, and the amount of Al ₂ O ₃ powder was 20%.

As manganese dioxide, pyrolusite (main component content not less than 90% by weight) is used, which is preliminarily ground in a pulverizer to a particle size of not more than 240 μm, preferably not more than 100 μm.

For plasticization, nitric acid (solid modulus 0.15 to 0.20) is added to the catalytically active mass (working mixture) prepared in a mixer and the mass obtained is mixed for 30 to 40 min to form a homogeneous paste. The readiness of the mass for molding is determined visually. If a high-viscosity mass is obtained, a small amount of water is added, if a low-viscosity mass is obtained, aluminum oxide powder is added.

Polyvinyl alcohol, polyethylene glycol, cellulose, starch, sawdust, stearic acid and/or commercially available derivatives thereof or mixtures thereof may be used as plasticizing additives in amounts of 0.1 to 15.6 wt.%.

The molding is carried out on a screw or plunger press with a string cutter. When molding, the paste-like mass is pressed through a die to form an extrudate with the desired cross-sectional geometry (Figure 2). The extrudate is cut into pieces of equal length with a cutter. The length of the molded piece is 10 to 250 mm. The obtained piece has the shape of a parallelepiped (rectangular prism).

The resulting workpiece is air-dried at a temperature of 18 to 20° C. and a humidity of 20 to 50% for 1 to 16 days.

After air drying, the honeycomb catalyst is dried in a chamber dryer at a temperature of 20 to 120° C. and a humidity of 20 to 90% for 60 to 400 h.

During the drying step of the pellets, free water is removed:

AlO(OH)·xH ₂ O→AlO(OH)+xH ₂ O

AlO(OH) _1-y (NO ₃ ) _y ·xH ₂ O→AlO(OH) _1-y (NO ₃ ) _y +xH ₂ O.

The dried extrudates were calcined in two steps.

Low temperature calcination is carried out in a belt kiln, with the catalyst loading not exceeding 25% of the total kiln volume. As the belt moves, the product is delivered to the calcination zone, where calcination is carried out at a temperature of 630 to 650°C for not less than 4 hours.

The following processes occurred during the low-temperature calcination of the honeycomb catalyst:

- Removal of structural water and dehydration of aluminum hydroxide and formation of aluminum oxide

2AlO(OH)→γ-Al ₂ O ₃ +Н ₂ О;

- Basic aluminum nitrate decomposes to form aluminum oxide, nitrogen dioxide and water

2AlO(OH) _1-y (NO ₃ ) _y →А1 ₂ О ₃ +yNO ₂ +(1-y)Н ₂ О;

- Combustion of combustible additives (sawdust) and plasticizers

С+О ₂ →СО ₂ ;

- Interaction of the formed nitrogen dioxide with sawdust carbon

NO ₂ +C→CO ₂ +1/2N ₂ ;

-Conversion of manganese dioxide

4MnO ₂ →2Mn ₂ O ₃ +О ₂ .

The high temperature calcination of the honeycomb catalyst is carried out in a belt kiln or a batch kiln. The product is placed in a calcination zone, where it is calcined at a temperature of 900-980°C for not less than 4 hours.

During the high temperature calcination of the honeycomb catalyst, further conversion of manganese(III) oxide occurred:

6Mn ₂ O ₃ →4Mn ₃ O ₄ +О ₂ .

The properties of the honeycomb catalyst are characterized by the values shown in the rows of Table 1.

The honeycomb catalyst included 4.5 wt.% of Мn ₂ O ₃ .

The monolith has a rectangular prism shape, a channel size of 3.1 mm, a channel wall thickness of 0.9 mm, _{a specific surface area} S = 15 ^m2 /g; a total pore volume of 0.3 ^cm3 /g, with transport pores accounting for 41% of the total pore volume.

Example 2

The catalyst was prepared in a manner similar to that of Example 1, the only difference being the catalyst composition, the monolith having the shape of a right rectangular prism, the substrate side being 150 mm, the height being 300 mm, the wall thickness being 0.9 mm, the channel side dimension being 1.6 mm, S _{specific surface area} = 18 ^m2 /g; the total pore volume being 0.37 ^cm3 /g, the transport pores accounting for 50% of the total pore volume. TAA with n = 0.3 was used.

Example 3

The catalyst was prepared in a manner similar to that of Example 1, using ramsdellite as the manganese dioxide, except for the catalyst composition and monolithic shape.

The monolith had a hexagonal prism shape, channel size of 1.6 mm, channel wall thickness of 0.5 mm, S _{surface area} = 20 ^m2 /g, total pore volume of 0.33 ^cm3 /g, transport pores accounting for 37% of the total pore volume. TAA with n = 1.5 was used.

Example 4

The catalyst was prepared in a manner similar to that of Example 1, using ramsdellite as the manganese dioxide, except for the catalyst composition and monolithic shape.

The monolith has a hexagonal prism shape, a channel size of 1.6 mm, a channel wall thickness of 0.5 mm, _{a specific surface area} S = 45 ^m2 /g, a total pore volume of 0.31 ^cm3 /g, and transport pores account for 70% of the total pore volume (Figure 1).

Example 5A. Preparation of a catalyst for low temperature oxidation of VOCs.

The working mixture was prepared by mixing the required amounts of binder - aluminum hydroxide powder, copper (II) oxide powder and organic additives (eg sawdust) in a rotor mixer for 10 to 120 min and then in a mixer with a Z-blade for 5 to 45 min.

As aluminum hydroxide, a product of rapid partial dehydration of gibbsite (TAA) is used, wherein n=0.9, comprising not less than 40 wt.% of shaped boehmite, having an average particle size of 30 μm, a specific surface area of about 250 m ² /g, a loss on drying (LOD) of not more than 18%, and a loss on ignition (LOI ⁸⁰⁰ ) of 28 to 32%.

As copper oxide, calcined copper hydroxide (the weight fraction of the main component is not less than 98%) is used, which is ground in a pulverizer to a particle size of not more than 120 μm, preferably not more than 50 μm.

For plasticization, nitric acid (solid modulus 0.15 to 0.20) is added to the catalytically active mass (working mixture) prepared in a mixer and the mass obtained is mixed for 30 to 40 min to form a homogeneous paste. The readiness of the mass for molding is determined visually. If a high-viscosity mass is obtained, a small amount of water is added, if a low-viscosity mass is obtained, aluminum oxide powder is added.

As alumina, precalcined highly dispersed γ-Al ₂ O ₃ (the weight content of the 40 μm fraction is not less than 60%) is used.

The amount of TAA was 20 wt.%, and the amount of γ-Al ₂ O ₃ powder was 80%.

Polyvinyl alcohol, polyethylene glycol, cellulose, starch, sawdust, stearic acid and/or commercially available derivatives thereof or mixtures thereof may be used as organic additives in an amount of 0.1 to 15.6 wt.%.

The forming is carried out on a screw or plunger press with a string cutter. When forming, the pasty mass is pressed through a die to form an extrudate with the desired cross-sectional geometry. The extrudate is cut into pieces of equal length with a cutter. The length of the formed piece is 10 to 250 mm. The obtained piece has the shape of a parallelepiped.

The resulting shaped monolithic workpiece is air-dried at a temperature of 18 to 20° C. and a humidity of 20 to 50% for 1 to 16 days.

After air drying, the formed monolith is dried in a chamber dryer at a temperature of 20 to 120° C. and a humidity of 20 to 90% for 60 to 400 h.

During the drying step of the pellets, free water is removed:

AlO(OH)·xH ₂ O→AlO(OH)+xH ₂ O

AlO(OH) _1-y (NO ₃ ) _y ·xH ₂ O→AlO(OH) _1-y (NO ₃ ) _y +xH ₂ O.

The dried shaped monolith is calcined in a belt kiln, with the catalyst loading not exceeding 75% of the total volume of the kiln. As the belt moves, the product is delivered to the calcination zone, where it is calcined at a temperature of 430 to 650°C for not less than 4 hours.

During calcination of the dry shaped monolith the following processes take place:

- Removal of structural water and dehydration of aluminum hydroxide and formation of aluminum oxide

2AlO(OH)→γ-AL ₂ O ₃ +Н ₂ О;

- Basic aluminum nitrate decomposes to form aluminum oxide, nitrogen dioxide and water

2AlO(OH) _1-y (NO ₃ ) _y →А1 ₂ О ₃ +yNO ₂ +(1-y)Н ₂ О;

- Combustion of combustible additives (sawdust) and plasticizers

С+О ₂ →СО ₂ ;

- Interaction of the formed nitrogen dioxide with sawdust carbon

NO ₂ +C→CO ₂ +1/2N ₂ ;

The monolith has a rectangular prism shape, with a base side of 100 mm, a height of 100 mm, a channel size of 1.8 mm, a wall thickness of 0.9 mm, S _{specific surface area} = 126 ^m2 /g; the total pore volume is 0.48 ^cm3 /g, and transport pores account for 51% of the total pore volume.

Example 5B

The catalyst was prepared in a manner similar to that of Example 5A, the only difference being the catalyst composition. For plasticization, nitric acid solution and CrO ₃ were added to the prepared catalytically active material (working mixture) in the mixer.

As shown by the examples provided, the catalyst as a honeycomb monolith preferably has a specific surface area greater than 1 m ² /g, depending on the calcination temperature, high strength, thermal stability and high activity.

According to the proposed solution, for the production of a catalyst as a honeycomb monolith for different heterogeneous reactions, proposed is a method for producing this catalyst that allows obtaining open transport pores with a size ranging from 50 to 500 nm, which represent no less than 35% of the total pore volume.

It is known that the high pressures required to extrude a monolith with a high channel density lead to an increase in the density of the material in the surface layer of the channel walls. As a result of the high temperature treatment, the surface layer of the walls is sintered, while a molten shell with a low specific surface area is formed. This impermeable shell restricts the access of reagents to the inner layers of the monolith and thus significantly reduces the active surface.

The proposed solution using as precursor of alumina a mixture of an aluminum compound of formula Al ₂ O ₃ ·nH ₂ O (where 0.3≤n≤1.5) obtained by rapid partial dehydration of gibbsite (TAA) and alumina powder in specific ratios allows solving this problem, keeping a high flow rate of the reagents in the inner wall of the honeycomb catalyst and thus increasing the heat and mass transfers.

Industrial Applicability

The proposed catalyst can be used for industrial waste gas treatment, selective reduction of nitrogen oxides and oxygen, ozone destruction, and fixed-bed catalytic dehydrogenation of low-level alkanes, alkenes, and aromatic alkanes to produce corresponding alkenes, chain dienes, and aromatic alkenes.

Claims (20)

1. A catalyst for heterogeneous reactions involving deep oxidation of hydrocarbons and carbon monoxide, made from a catalytically active material containing an active component, alumina, into a honeycomb monolith with rectangular honeycomb channels, characterized in that, A mixture of an aluminum compound of the formula Al ₂ O ₃ ·nH ₂ O where 0.3 ≤ n ≤ 1.5 and alumina powder obtained by rapid partial dehydration of gibbsite is used as a precursor of alumina in a ratio of 20 to 80 wt.%. Al ₂ O ₃ ·nH ₂ O wherein 0.3 ≤ n ≤ 1.5 and 80 to 20 wt.% alumina powder, wherein the channel walls have open transport pores with a size of 50 to 500 nm, and the open transport pores account for 50% of the total pore volume 35 to 70%, and the active component includes a metal or metal compound selected from the group of manganese, chromium, copper and iron or a mixture thereof. 2. The catalyst according to claim 1, characterized in that the particle size of the active component is not greater than 20 to 50 nm, and the amount of metal or metal compound included in the active component is 2 to 2 in terms of metal oxide. 30wt.%. 3. The catalyst according to claim 1, characterized in that the side of the rectangular monolithic substrate is 20 to 150mm, the height is 30 to 1470mm, the thickness of the channel wall is 0.1 to 2mm, and the size of the channel side is 0.1 to 19.9 mm, the number of channels per square inch of the monolithic cross-section is 1.5 to 250 cpsi. 4. The catalyst according to claim 1, wherein the honeycomb monolith is shaped into a right hexagonal prism or a right rectangular prism, and the inner walls of all honeycomb channels have the same thickness. 5. The catalyst according to claim 1, characterized in that grooves are made on the outside of the honeycomb monolith, and the depth of the grooves is equal to 1/2 of the side of the honeycomb channel. 6. The catalyst according to claim 1, characterized in that the catalyst includes a metal or a metal compound selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, metal alkali carbonates or mixtures thereof. 7. The catalyst according to claim 6, characterized in that the metal or the metal compound comprises Na, K, Ba, Al, Si, V, Co, Ni, Zn, Mo, Ag, Sn, One or more metals of La and Ce. 8. The catalyst according to claim 7, characterized in that the catalyst includes titanium dioxide, zirconium dioxide, metal aluminates or mixtures thereof. 9. The catalyst according to any one of claims 1 to 8, characterized in that the catalyst has a specific surface area of 1 to 100 ^m2 /g, a bulk density of 0.4 to 1.4g/ ^cm3 , and a mechanical strength of Less than 6.0MPa, the liquid flow resistance of the bed is not greater than 280Pa/m at a flow rate of 0.5m/s. 10. A method for producing a catalyst for a heterogeneous reaction comprising deep oxidation of hydrocarbons and carbon monoxide according to any one of claims 1 to 9, the method comprising the following steps: A powder material is prepared from the components of the catalytically active substance, which is mixed with a binder based on an aluminum compound, a plasticizer, a pore structuring additive including a flammable pore structuring additive to obtain the catalytically active substance, which is extruded through a die Shaping to produce a shaped element as a honeycomb monolith with rectangular honeycomb channels, air-drying, drying and calcining, characterized in that, for shaping, the formula Al ₂ O ₃ · obtained by rapid partial dehydration of gibbsite is used nH ₂ O A mixture of a binder and alumina powder of an aluminum compound where 0.3 ≤ n ≤ 1.5, in a ratio of 20 to 80 wt.% of the formula Al ₂ O ₃ ·nH ₂ O where an aluminum compound of 0.3 ≤ n ≤ 1.5 and 80 to 20 wt.% alumina powder, wherein the channel walls have open transport pores with a size of 50 to 500 nm, the open transport pores accounting for 35 to 70% of the total pore volume, the mixture is preliminarily processed by combined grinding or separate grinding Activation, mixing with a component of a catalytically active substance including a metal or a compound of a metal selected from the group of manganese, chromium, copper, iron or a mixture thereof, a plasticizing additive and a pore structuring additive, and the obtained catalytically active substance is plasticized It is formed, formed, air-dried, and then dried at a temperature gradually increasing from 40 to 120°C, and calcined at a temperature of 300 to 1200°C for 1 to 16 hours. 11. The method according to claim 10, characterized in that the aluminum compound of the formula Al ₂ O ₃ ·nH ₂ O, where 0.3≤n≤1.5, has an average particle size of 30 μm after activation by grinding. 12. Method according to claim 10, characterized in that pyrolusite and/or harzburgite, which has been preliminarily ground in a pulverizer to a particle size of no more than 40 μm, is used as the manganese compound. 13. The method according to claim 10, characterized in that polyvinyl alcohol or isopropyl alcohol, polyethylene glycol, cellulose, starch, urotropine, sawdust are used in an amount of 0.1 to 15.6 wt.% , stearic acid and/or its commercial derivatives or mixtures thereof as plasticizing additives. 14. Method according to claim 10, characterized in that nitric acid having an acid modulus of 0.10 to 0.30 is used for plasticizing the catalyst working mixture. 15. Method according to claim 10, characterized in that the shaped monolith is air-dried for 7 to 14 days at a temperature of 18 to 20°C and a relative humidity of 20 to 90%. 16. Method according to claim 10, characterized in that the monolith is dried at a relative humidity of 20 to 90% for 7 to 21 days. 17. Method according to claim 16, characterized in that the calcination is carried out at a temperature of 350 to 500°C for 2 to 8 hours. 18. The method according to claim 10, characterized in that low-temperature calcination is performed at a temperature of 400 to 600°C for not less than 1 to 6 hours, and then high-temperature calcination is performed at a temperature of 900 to 980°C for not less than 1 to 6 hours. hours, optionally followed by increasing the temperature to 1200°C. 19. The method according to any one of claims 10 to 18, characterized in that after 100 to 200 heating cycles from room temperature to 800°C and cooling to room temperature in a muffle furnace in air, the strength is not low. at 4.0MPa. 20. A catalytic process for the deep oxidation of hydrocarbons and carbon monoxide using a catalyst according to any one of claims 1 to 9 produced by a method according to any one of claims 10 to 19, It is characterized in that the catalytic process includes the step of contacting the reaction mixture with the catalyst under catalytic reaction conditions.