Catalyst carrier and method thereof

 

(57) Abstract:

The invention relates to the field of technical chemistry, namely, carriers for catalysts that can be used in various heterogeneous catalytic processes in the chemical industry. Describes the media that contains ceramic matrix based on aluminum oxide and the material dispersed throughout the matrix, as a dispersed material media contains the oxides of transition and/or rare earth metals, or their mixture, and/or metals and/or alloys, and/or carbides of metals of the 4th period of the Periodic table, or their mixture, in the form of particles or aggregates of particles with size from 1 to 250 μm, when the content of the dispersed material in the matrix of 0.5-70 wt.%, this media contains a system of parallel and/or intersecting channels. The preparation method of the carrier includes obtaining a homogeneous mass containing sintered ceramic material of the matrix and the dispersed material, molding the mass into the desired shape, the heat treatment of the molded mass at a temperature sufficient for sintering of the matrix material, as the material of the ceramic matrix use powder containing metallic aluminum or vpityvayut fiber and/or fabric materials, forming in the body of the monolith during sintering system parallel and/or intersecting perpendicular channels, before heat treatment formed the mass of the pre-treated under hydrothermal conditions. The technical result - the creation of a catalyst carrier, resistant to thermal shocks and high specific surface area. 2 S. and 1 C.p. f-crystals.

The invention relates to the field of technical chemistry, namely monolithic carriers for catalysts, including cell structure, which can be used in a variety of heterogeneous catalytic processes in the chemical industry, such as full and partial oxidation of hydrocarbons, steam reforming, and others.

Well-known and widely used heterogeneous catalysts in the form of blocks (cell structures) of different ceramic materials [GB 1375830, B 01 J 11/06, 1973], which allows to reduce the hydraulic resistance of the catalyst layer. The usual drawback of such honeycomb structures is their low specific surface area [GB 1375830, B 01 J 11/06, 1973; EP 0197681, B 01 J 37/00, 18.03.1986]. This reduces the activity of the catalysts produced from such honeycomb structures, because it reduces the amount of applied active componentui structures and increase the number of channels per unit of cross-section of the block. In addition, on the surface of the cell carriers in addition put a highly porous substrate made of aluminum oxide, silicon, rare earth elements. The latter technique requires special preparation of the materials of which make the substrate, the introduction of additional stages in the manufacturing process of the media [US 3824196, B 01 J 11/06, 1974]. In addition, due to differences in coefficients of thermal expansion may exfoliation of highly porous layer by thermal shock, which is typical for any exothermic catalytic processes. Derived from such media, the catalysts have a scarce resource, less resistant to catalytic poisons.

A fundamentally different approach is focused on the manufacture of the monolithic honeycomb carrier immediately with a high specific surface. So, in the US 4294806, B 01 D 53/36, 13.10.1981, monolithic carrier is aluminum oxide with a high specific surface. However, the media has insufficient mechanical strength and resistance to thermal shocks. In Pat. RF 2093249, B 01 D 53/06, 22.12.1992, described cell media for oxidation catalyst containing aluminum oxide and silicon oxide. thermal stability of the obtained cell media not only to use these media for the manufacture of catalysts for fuel combustion or partial oxidation of methane into synthesis gas, requiring thermal stability at higher temperatures.

Closest to the claimed is a monolith with increased thermostability [US 4637995, B 01 J 23/75, 20.01.1987] containing 50-90 wt.% sintered ceramic matrix material and 10-50 wt.% material with a high specific surface, dispersed throughout the matrix. The material of the ceramic matrix consists of cordierite, mullite, alpha-alumina, or mixtures thereof. The particle size of the matrix material does not exceed 70 μm (200 mesh). Dispersed material has a specific surface area of not less than 40 m2/g and a crystallite size of not more than 0.5 μm and consists of sulphides of transition metals or mixtures thereof, porous oxides on the basis of aluminum oxide, Zirconia, spinel-based aluminate magnesium, silica, zeolite, titanium oxide or their mixtures, and their mixtures with sulfides of metals.

A disadvantage of the known media is the use of silicon-containing compounds, which significantly reduce the stability of the monoliths to sintering due to the relatively low melting temperature than aluminum oxide [Quick reference chemist. L.: Chemistry, 1978]. Sulfides of metals at high temperature sintering oxidized that ashrah, the reaction is carried out in the diffusion region, it is therefore very high specific surface area is not required. Much more important, that these carriers were resistant to thermal shocks and, if possible, had the high conductivity to reduce the possibility of local overheating. Such properties are composite materials.

The invention solves the problem of obtaining a carrier having a sufficiently high specific surface area with uniform distribution of pores throughout the thickness of the substrate, increasing resistance to local overheating and resistance to thermal shock (rapid temperature changes), as well as increasing the geometric surface of the media.

The problem is solved using the catalyst carrier containing a ceramic matrix and the material, while dispersed throughout the matrix material consists of coarse particles or aggregates of particles, which is a metal oxide, and/or metals, or their alloys, and/or carbides of metals, or any mixture that is different from the matrix composition and structure, and the content of the dispersed material is 0.5-70 wt.%, this media contains a system of parallel and/or intersecting channels.

the diamonds in the media center hole, different from the channel size and shape.

The task of creating media is solved:

1) through the formation of a matrix based on oxide of aluminum, having a relatively high specific surface area and does not contain oxides of silicon;

2) through the use of dispersed material in the amount of 0.5-70 wt.% with a relatively low specific surface consisting of metal oxides and/or metals, or their alloys, and/or carbides of metals, different from the matrix composition and structure;

3) through the use of dispersed material with a large enough particle size of 1-250 microns;

4) through the formation in a unit cell structure of an additional system of intersecting channels.

The use of a matrix that does not contain low-melting compounds, allows to maintain a high porosity and after overheating. The presence of coarse dispersed material, including metals or metal carbides, reduces mechanical and thermal stress in local overheating by increasing the heat capacity of the composite media and reinforcing properties of the coarse fraction. System of intersecting channels increases geometric is about, for durable fixing of the carrier in case you can use storage media with a hole in the center, with a larger diameter than the cell channels, sufficient to securely fasten received from the carrier of the catalyst in the case.

The task of preparing the proposed media is solved in a special way. Structural features of the proposed media determine the method of its preparation. Usually, to obtain a mixture, which is formed of a monolithic carrier is used, at least three components:

a) a ceramic material that provides mechanical strength and, as a rule, thermostability;

b) inorganic (fixed) link that provides bonding of the particles of ceramic material and a high specific surface area;

in) organic (temporary) binder, providing the necessary rheological properties of the moldable paste [EP 0197681, B 01 J 37/00, 18.03.1985; US 3824196, B 01 J 11/06, 16.07.1974]. The disadvantages of this method include forming honeycomb structures of these pastes by extrusion, which leads to significant compaction of the material. Therefore, in the manufacture of monolithic honeycomb structures by this method the specific surface somethingbecause based aerosoles, received by the freezing of Aerosil with subsequent thawing and drying [U.S. Pat. RF 2093249, 01 D 53/06, B 01 J 23/76, 22.12.1992]. However, stage pre-treatment of the powder of silicon dioxide, which significantly complicates the preparation of a carrier. In [US 4294806, B 01 D 53/36, 13.10.1981] described the method of preparation of monolithic carrier based on alumina, in which the calcination and sintering of the material was performed only in the front. However, the heterogeneity of the heat treatment may lead to cracking of the ceramic material.

In [US 4637995, B 01 J 23/75, 20.01.1987], we have chosen as a prototype for the method of preparation described method, including the formation of a homogeneous mass consisting of:

a) material of sintered ceramic matrix, consisting of particles with a size less than 70 microns (200 mesh) on the basis of cordierite, mullite, alpha-alumina, lithium silicate or mixtures thereof in the amount of 50-90 wt.%;

b) a material with a high specific surface, having a crystallite size of not more than 0.2 μm and a specific surface area of not less than 40 m2/g, based on sulphides of transition metals, porous alumina, Zirconia, spinel, silicon, titanium, zeolite or mixtures thereof in the amount of 10-50 wt.%.

CCI.

The disadvantages of the described method should include the following 1) use as matrix materials only oxides is not possible to obtain porous monoliths with high mechanical strength and resistance to thermal shocks and do not require long-term high-temperature processing, contributing to the diffusion sintering;

2) use as an additional material fine particles with high surface area leads to a significant shrinkage of the material during annealing, and reduces the mechanical strength of the monoliths;

3) forming honeycomb structures by extrusion, leads to the formation of nonequilibrium structures, which also requires long-term high-temperature processing.

The problem is solved by the method of preparation of the catalyst carrier containing ceramic matrix material dispersed throughout the matrix, including the production of a homogeneous mass containing sintered ceramic material of the matrix and the dispersed material, molding the mass into the desired shape, the heat treatment of the molded mass at a temperature sufficient for sintering of the matrix material. As a material of the ceramic matrix and the new materials, forming in the body of the monolith during sintering system parallel and/or intersecting perpendicular channels, before heat treatment formed the mass of the pre-treated under hydrothermal conditions. As the dispersed material used powdered metal oxides, and/or powdered metals and/or alloys, and/or carbides of metals, or any mixture, the content of dispersed material is 0.5-70 wt.%.

The preparation method of the carrier according to the invention includes:

1) use as a material for ceramic matrix of aluminum powder or powders on the basis of the oxides or hydroxides of aluminum with the addition of aluminum powder;

2) use as an additional material powder particles of large size 1-250 μm, which perform a reinforcing function, and application of metals and carbides improve thermal properties of the media;

3) obtain a homogeneous mass, including aluminum powders and powder of the additional material;

4) impregnation of a homogeneous mass of fibrous or textile materials, burnable when vysokotemperaturno icemaw for gaseous substances;

6) processing a homogeneous mass under hydrothermal conditions before calcination in air.

Aluminum powder, interacting with water, is oxidized to form hydroxides, which leads to an increase in the volume of the solid body and samouprave a homogeneous mass in a mechanically stable monolith. When ignition occurs thermal decomposition of the hydroxides of aluminum with the formation of a highly porous matrix of aluminum oxide, and finally oxidized aluminum metal with the formation of elongated oxide particles, which are reinforced particles of the porous matrix and increase its resistance to thermal shocks. In addition, burnable fibers after heat treatment in air is formed through parallel channels in the body of the monolith with rough walls. Burnable materials after heat treatment in air form the system of intersecting perpendicular to each other channels.

It should be noted that the method of preparation of media, including the use of aluminum powder mixed with powdered non-volatile components, placing the resulting mass in a molding device, permeable to gaseous substances, with subsequent treatment with water vapor already izveidosanos, fade in the air. It is not possible to produce a honeycomb structure.

There is also known a method of obtaining a carrier of honeycomb structure including a layer-by-layer stacking saturated paste-like mass of fibers and vigorish forming elements with a subsequent heat treatment [U.S. Pat. RF 1680305, B 01 J 37/02, 09.01.1989]. However, this method does not include the added weight of aluminum powder and hydrothermal processing of the product, which significantly reduces its mechanical strength. In addition, this method does not allow to produce a system of channels that intersect perpendicularly to each other, which increases the area of the geometric surface of the monolith. Thus, in the proposed method for the preparation of monolithic media is a special combination of known techniques, creating novelty of the invention.

As oxides in the present invention can be used in simple and mixed oxides of transition and rare earth elements of the Periodic table. As metals, alloys and carbides are mainly used metals 4 period. Can be used and other transition elements of the Periodic table. The average particle size of metals, alloys and to the aggregates of oxide particles is determined by the method of Coulter. In some cases, the particle size is determined by sieving method. Specific surface area determined by BET method [A. P. Karnaukhov Adsorption. Texture, particle size and porosity of the materials. Novosibirsk: Nauka, 1999].

The invention is illustrated by, but not limited to, the following examples:

Example 1. The aluminum powder is mixed with the dispersed material is a mixed oxide LaNiOthe 2.5with perovskite structure with an average size of aggregates of particles of about 15 μm, but with a wide range of size distribution from 1 to 25 μm. The resulting powder was mixed with a solution of glycerine in water. The obtained suspension moisten a cotton cloth in the form of a tape, on top of which is placed cotton yarn thickness 1 mm parallel to each other and perpendicular to the length of the tape. Then the tape rolled into a cylinder, which lay in the molding device and placed in the autoclave. Autoclave molding device steamed, resulting in part of aluminum powder is oxidized, and the powder is grasped in the monolith. After autoclaving the moulder is dried and calcined to a temperature of at least 1000°C, resulting in the remaining part of the aluminum doomey specific surface area of 5 m2/so the Number of concurrent channels per unit geometric surface of the end plane is 56 cm-2. The distance between the intersecting channels is 0.5 mm, the content of the dispersed material is 22 wt.%.

Example 2. Similar to example 1. Characterized in that, as the dispersed material used powder CEO2with the structure With double oxide having the average size of aggregates of particles of 7 μm. Received the product cell structure has a specific surface area of 10 m2/, the Number of channels per unit geometric surface of the end plane is 40 cm-2. The distance between the intersecting channels is 5 mm, the content of the dispersed material is 26 wt.%.

Example 3. Similar to example 1. Characterized in that, as the dispersed material used powdered Nickel (fraction of 100-250 μm) and aluminum powder added powdered aluminum hydroxide.

Received the product cell structure has a specific surface area of 3 m2/, the Number of channels per unit geometric surface of the end plane is 40 cm-2. The content of dispersed maternova material used powdered alloy Fe-Cr-Al, having an average particle size of 5 μm. Received the product cell structure has a specific surface. The number of concurrent channels per unit geometric surface of the end plane is 35 cm-2. The content of the dispersed material is 70 wt.%.

Example 5. Similar to example 1. Characterized in that, as the dispersed material used powder of solid solution on the basis of oxides of La, CE, Zr having an average size of aggregates of particles of 8 μm, and a powder alloy Ni-CR, and having an average particle size of 60 μm. Received the product cell structure has a specific surface area of 12 m2/, the Number of channels per unit geometric surface of the end plane is 230 cm-2. The content of the dispersed material is 26 wt.%. solid solution on the basis of oxides of La, CE, Zr and 9 wt.% alloy Ni-Cr.

Example 6. Similar to example 3. Characterized in that, as the dispersed material used TiC powder having an average particle size of 3 μm. Received the product cell structure has a specific surface area of 2 m2/, the Number of channels per unit geometric surface of the end plane is 40 cm-2. Sudarianto as dispersed material used TiC powder analogously to example 6 and the powder CeO2analogously to example 2. Received the product cell structure has a specific surface area of 9 m2/, the Number of channels per unit geometric surface of the end plane is 40 cm-2. The content of the dispersed material is 12 wt.% TiC and 8 wt.% SEO2.

Example 8. Similar to example 7. Characterized in that, as the dispersed material optionally use the powdered alloy NiCr having an average particle size of 60 μm. Received the product cell structure has a specific surface area of 4 m2/, the Number of channels per unit geometric surface of the end plane is 230 cm-2. The content of the dispersed material is 12 wt.% TiC; 8 wt.% SEO2; 6 wt.% NiCr.

The obtained solid media showed good results when tested for thermal shock. I.e., the carriers are not destroyed by heating them for a few minutes up to 1200°C.

Thus, as can be seen from the above examples, the present invention solves the technical problem of creating a catalyst carrier is resistant to thermal shocks and high specific surface area.

1. Catalyst carrier containing ke as dispersed material media contains the oxides of transition and/or rare earth metals, or their mixture, and/or metals and/or alloys, and/or carbides of metals of the 4th period of the Periodic table, or their mixture in the form of particles or aggregates of particles with size from 1 to 250 μm at a content of dispersed material in the matrix of 0.5-70 wt.%, this media contains a system of parallel and/or intersecting channels.

2. Catalyst carrier under item 1, characterized in that it can have a hole in the middle that is different from the channel size and shape.

3. The method of preparation of the catalyst carrier containing ceramic matrix based on aluminum oxide and the material dispersed throughout the matrix, including the production of a homogeneous mass containing sintered ceramic material of the matrix and the dispersed material, molding the mass into the desired shape, the heat treatment of the molded mass at a temperature sufficient for sintering of the matrix material, wherein the material of the ceramic matrix use powder containing metallic aluminum or powder-based oxides or hydroxides of aluminum and aluminum metal, a homogeneous mass of impregnated fibrous and/or fabric materials, forming in the body of the monolith during sintering system pair is t under hydrothermal conditions, and as dispersed material used oxides of transition and/or rare earth metals, or their mixture, and/or metals and/or alloys, and/or carbides of metals of the 4th period of the Periodic table, or their mixture in the form of particles or aggregates of particles with size from 1 to 250 μm, and the content of the dispersed material is 0.5-70 wt.%.



 

Same patents:

The invention relates to a method for preparing a multi-component catalyst for the oxidation of propylene to acrolein

The invention relates to the field of preparation of supported catalysts and can find application in various sectors of the chemical industry

The invention relates to the production of spherical granules of catalyst

The invention relates to the field of pyrolysis of hydrocarbons
The invention relates to the production of catalysts for ammonia synthesis and can be used in the nitrogen industry
The invention relates to the field of chemistry, and in particular to methods of preparation of catalysts for the conversion of light hydrocarbons to high octane motor fuel components

The invention relates to catalysts, catalyst carrier, process for their preparation and methods of purification of exhaust gases from the NOxincluding flue gases of thermal power plants, exhaust gases of cars, as well as in the production of nitric acid

The invention relates to a process for the preparation of catalysts based on copper compounds and zinc for low-temperature conversion of carbon monoxide with water vapor and can be used in the chemical and petrochemical industry, for example, in the production of ammonia and hydrogen, the synthesis of methanol and other industries
The invention relates to the field of petrochemicals

The invention relates to the refining and petrochemical industries, in particular to methods of producing catalysts for the conversion of aliphatic hydrocarbons WITH2-C12in high-octane gasoline and/or aromatic hydrocarbons

The invention relates to the production, accompanied by emissions of nitrogen oxides
Up!