The composition of the charge for a highly porous material with mesh - mesh structure for catalysts carriers

 

(57) Abstract:

Highly porous ceramic materials with mesh-wire mesh structure can be widely used as a stationary object catalysts for the conversion of natural gas, smelting reduction of unsaturated hydrocarbons, aromatic nitro compounds, aldehydes, ketones, carboxylic acids and other products made of a highly porous ceramic materials obtained by reproduction of the structure of open-celled foamed polyurethane foam by spraying a ceramic powder containing a filler and active to the sintering of the alumina powder with the addition of a binder, with the subsequent burning of the substrate and heating the remaining ceramic frame to a temperature of 1450-C. The total porosity of the ceramic product is 85-92% open porosity jumper between cells 20-30% with a pore size of 1-2 microns. Samples of highly porous ceramics can withstand a static load of from 0.5 to 2.0 MPa, depending on the composition and thermal treatment regimes. table 1.

The invention relates to the field of chemical technology highly porous ceramic materials with mesh-cellular structure, which can widely ispolzovaniya unsaturated hydrocarbons, aromatic nitro compounds, aldehydes, ketones, carboxylic acids and others, as well as filters for metals, high-temperature insulation materials and other purposes.

Invented a highly porous materials with mesh-mesh structure obtained by reproduction of the structure of open-celled foamed polyurethane by applying a ceramic powder containing a filler and active to the sintering of the alumina powder with additives in the form of a slurry in various bundles with the subsequent burning of the substrate and heating the remaining ceramic frame to a temperature at which the ceramic product acquires the specified properties. The total porosity of the ceramic product is 85-92% open porosity jumper between cells 20-30%, which have a pore size of 1-2 microns. Samples of highly porous ceramics can withstand a static load of 0.5 to 2 MPa, depending on composition and heat treatment temperature.

Fabrication of highly porous ceramic materials with mesh-cellular structure currently used mainly aluminosilicate materials, the slip which is applied on the open-celled polyurethane foam, and indelity corundum obtained on the basis of powdered alumina with an average particle size less than 1 μm. Sintering is carried out at a temperature S [Century. N.Antsiferov, S. E. Morozova. Highly porous permeable materials based on silicates Perm, 1996, 207 S.].

A feature of these materials is the practical absence of open porosity jumpers cells, low specific surface area, high shrinkage in the range of 10-20%, which leads to the formation of the taper, deformation and lack of maintenance of accurate shape and size of the product. Properties of samples on the basis of silicates differ little among themselves, and have, for example, highly porous aluminous porcelain (prototype) [C. N. Antsiferov, C. N. Ovchinnikov, S. E. Morozova, I. C. Fedorov. Highly porous cellular ceramic materials, glass and ceramics, 1996, No. 9, S. 19-20] the following values:

- an apparent density of 0.2-0.3 g/cm3;

- open volumetric porosity is about 80 to 98%;

- compressive strength of 0.1 - 0.5 MPa.

Such materials are not suitable for use as carriers of catalysts.

The technical problem consists in the manufacture of highly porous ceramic carrier catalysts with mesh-cellular structure, which upon firing, no shrinkage and deformation, and the jumper between cells have>The3on highly porous carrier by impregnation and subsequent calcination in the pores of the jumpers are formed of porous particles-Al2O3that increase specific surface area 3-4 times in comparison with the initial specific surface area of ceramic media, which is at level 2 m2/,

The technical result is achieved in that for the manufacture of highly porous ceramic material with mesh-cellular structure is an inert filler in the form of electro-fused corundum, silicon carbide, silica sand and dispersed oxide powder with additives of any metal oxides II and IV group of the periodic table in any quantity, active hardening products in the absence of shrinkage and deformation at temperatures in the range 1350-S), providing, in addition to the necessary hardening of workpieces, the formation of a microporous structure jumpers cells for the subsequent development of specific surface area burned products by impregnation of porous ceramics by the Sol of aluminum oxide and calcining in the following ratio of components:

the inert filler is 50-60 wt.%;

- dispersed powder aluminum oxide - 50-40 wt.%

with the population highly porous ceramic material with mesh-cellular structure is as follows.

Components of the charge - filler and disperse the alumina powder with additives, providing strengthening products during firing, is stirred in a ball mill, a dry method in the presence of grinding media with a ratio of material : balls 1:1 for at least 2 hours. In the resulting composition is administered to a temporary technological ligament in the form of a solution of PVA, dextrin or MC to get a specific viscous state, providing high-quality impregnation pieces of polyurethane foam. After impregnation, the excess slip is released and the workpiece is dried at a temperature of - 100-120C, so that they acquire a sufficiently high strength. Firing blanks is carried out in a furnace with an air atmosphere at a heating rate of providing slow burning out the basics without breaking the ceramic framework. The final firing temperature depends on the type of filler and the composition of the dispersed powder, providing strengthening products, and is 1350-C.

The resulting products have a porosity of up to 92% and a specific surface area of up to 2 m2/,

For the development of specific surface annealed product is impregnated with a Sol of aluminum oxide and subjected to heat treatment at temperatures of 860-1000C for again rises to 8-9 m2/g per the total mass of the carrier. After that, on the surface of the ceramic carrier is applied catalytically active component by impregnation with appropriate solutions. To ensure the activity of the resulting catalytic systems for a wide variety of chemical processes on the surface can be coated with metals, metal oxides, and their salts, complex, and other compounds used as a catalyst.

The composition of the charge for a highly porous material with mesh-mesh structure for carriers of catalysts consisting of inert filler: fused corundum, silicon carbide, silica sand, and dispersed powder aluminum oxide or other oxide compositions with additives of oxides of metals of the II and the IV group of the periodic table, providing strengthening of billet products in the absence of shrinkage and deformation at temperatures of 1350-S, characterized in that the components used in the following proportions:

Inert filler 50-60 wt.%

The dispersed powder aluminum oxide 50-40 wt.%

or other oxide compositions with

additives of oxides of metals of the II and IV groups

of the periodic table

 

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