The method of preparation of the catalyst

 

(57) Abstract:

The invention relates to catalytic systems, compositions, and more particularly to methods for bulk catalysts of honeycomb structure. The inventive catalytically active mixed metal oxide with an inorganic binder. As catalytically active oxides, a mixture of oxide of iron, chromium and zinc. The components of the catalyst is subjected to wet-milling. Press on the filter press to a moisture content of 28%. Is then formed on the air. Forming dried and calcined. table 2.

The invention relates to catalytic systems, compositions, and more particularly to methods for bulk catalysts of honeycomb structure. Block the catalysts used in the implementation process of complete oxidation of organic substances and carbon monoxide, including the processes of catalytic fuel combustion and post-combustion industrial gas emissions, emissions vehicles, as well as purification processes from sericoidini natural gas.

Known to block the catalysts of honeycomb structure used in the processes of complete oxidation and combustion chamber, which represents the catalytically active commonality specific surface area of these carriers operate applying an additional substrate on the basis of metal oxides II, Groups III and IV. Oxide film (additional substrate) is applied in a variety of ways, but regardless of how it has insufficient thermal stability and mechanical strength. The known method [1] preparation of the catalyst of this type. According to this method, to obtain firmly connected with the carrier film of aluminum oxide last put by repeated impregnation of the carrier suspensions of aluminum oxide in a solution of oxynitride aluminum. Usually after 3 times of application on the surface of the carrier film is formed of Al2O3, component 10-40% of its weight. On the thus prepared carrier by impregnation put active component: Pt or Pd in an amount of from 0.2 to 0.6 wt.

The catalysts obtained in this way have a high specific surface area and catalytic activity, however, their mechanical strength due to the presence of additional substrate is insufficient. The use of such catalysts at high temperatures is complicated by the low thermal stability of platinum group metals. In addition, the technology for these catalysts multistage.

Known catalyst [2] used in the cleaning process of extrudate in the form of cuttings, prepared by mixing precipitated hydroxides of iron and chromium, with subsequent drying and calcination. The catalyst contains 20-75 wt. iron oxide and 25-80 wt. oxide of chromium. The catalyst may include oxides of cobalt, Nickel, manganese, copper, zinc, titanium in the amount of 15-25 wt. The method of preparation of the catalyst [2] is the closest to the technical nature of the claimed method and is taken as a prototype.

The advantages of the catalyst [2] include the use of cheap and available raw materials and a high level of activity in sulfur-containing compounds. However, the catalysts in the form of cuttings do not have high enough strength and with increasing volumetric gas flow rate will be destroyed.

Block catalysts have a significantly lower hydraulic resistance compared with the same height of the layer of granular catalysts [3]

Known method of preparing the bulk catalyst comprising a mixture of catalytically active oxides with alumina and kaolin in the presence of water, then add binding and extrusion molded blocks cellular patterns [4]

The purpose of the invention preparation of block catalyst and, able to effectively clear away toxic compounds high-speed gas flows.

The objective is achieved by the fact that the source components: chromium oxide, iron oxide, zinc oxide, clay, bentonite, talc and magnesium sulfate, as well as balloons and water in the ratio of solid balls water 1:1:2 loaded into a ball mill and are wet milled for 2 hours the resulting mass was filtered on a filter press to a moisture content of 28% is then formed by extrusion in the form of blocks of cellular structure in the form of a square or hexagonal prisms of various sizes. Received blocks provalivajut in air, dried at 110oC, calcined at 700oC 4 h

Distinctive features of the prototype features are:

introduction to the catalyst composition of clay and other plasticizing binder and additives;

the implementation of the wet grinding of all catalyst components to obtain a homogeneous and plastic weight;

forming by extrusion blocks cell structure.

To illustrate the proposed method provides examples of specific performance. The strength of the catalysts on the crushing along generatrix defined on the device MP-9-C. To determine the strength was shaped catalytic mccoach oxidation of butane and direct oxidation of hydrogen sulfide to sulfur. The results of the tests of the catalysts are given in table. 1 and 2.

Example 1. Ball mill load 87 kg of a mixture of the original oxide (composition of mixture for all examples, wt. Cr2O344,8, Fe2O329,9, ZnO 25,3), plasticizing agents in the amount of 33 kg (20 kg clay, 4 kg of bentonite, 4 kg of talc, 5 kg MgCO3), 200 kg of balls and impose binding distilled water, bringing the volume of the mixture to 2/3 of the volume of the mill. Grinding lead for 2 h, then the mass is filtered on a filter press to a moisture content of 28% resulting mass is formed on the vacuum screw-press in the form of blocks of cellular structure. Unit dimensions:

hexagonal prism with a side of 45 mm, height 150 mm;

prism of square cross section HH mm;

prism of square cross section HH mm

Catalysts provalivajut in air, dried at 110oC 6 h, the calcining is conducted at 500, 700, 800, 900oC for 4 h the resulting catalyst composition, wt. Fe2O320,0, Cr2O336,5, ZnO 16,9, MgO 3,7, Al2O39,4, SiO213,5. The catalysts of the composition, calcined at different temperatures were tested in the oxidation of butane (the results are shown in table. 1). The catalytic activity of the prepared catalysts is determined by the prot is I butane X 60% test Conditions catalysts:

temperature 400oC;

the composition of the initial gas mixture: 0.5 to about. C4H10the rest of the air.

In addition, the catalyst calcined at 700oC, tested in the reaction of direct oxidation of hydrogen sulfide into elemental sulfur. The tests were carried out as follows.

The purified natural gas, containing about. H2S 4,2, CO24,3, CH461,4, hydrocarbons, C2-C529,1, with a temperature of 185oC 50 l/h is mixed with air in an amount of 10 l/h of the Obtained gas mixture was fed into the reactor containing 8 g of the catalyst. In the reactor at a temperature of 230oC is the catalytic oxidation of hydrogen sulfide. The reaction gas containing the formed sulfur and water, and unreacted components of the original gas mixture withdrawn from the reactor and cooled first to 130oC for condensation of sulfur vapor, then 90oC for condensation of water vapor. The catalyst was operated continuously for 600 including the results of the experiments are given in table. 2.

Example 2. Ball mill load 47 kg of a mixture of the original oxides, 40 kg of clay, 4 kg of bentonite, 4 kg of talc, 5 kg MgCO3balls, distilled water. The mixture is subjected to wet-milling for 2 is URS, provalivajut and subjected to heat treatment as in example 1. The resulting catalyst composition, wt. Fe2O314.4V, Cr2O324,0, ZnO 11,9, MgO 3,7, Al2O320,2, SiO225,7. The results of the tests of the catalysts are given in table. 1.

Example 3. Ball mill load 87 kg of a mixture of the original oxides, 4 kg of bentonite, 4 kg of talc, 5 kg MgCO3balls, distilled water. The mixture is subjected to wet-milling for 2 h, and then press on the filter press to a moisture content of 28% Received a lot ekstragiruyut in blocks of honeycomb structure, provalivajut and subjected to heat treatment as in example 1. The resulting catalyst composition, wt. Fe2O326,0, Cr2O339,0, ZnO 22,0, MgO 3,7, Al2O31,6, SiO27,7. The results of the tests of the catalysts are given in table. 1.

Example 4. For comparison with the catalyst prepared according to the method prototype, a mixture of initial oxides in the form of cuttings, calcined at 400oC, was tested in the oxidation reactions of butane and direct oxidation of hydrogen sulfide to sulfur. The chemical composition of the sulfurous gas and the operating conditions of the catalyst identical to the conditions given in example 1. The results are given in table. 1 and 2.

the 1 3) are at a high enough level. Strength values vary depending on the composition and temperature of calcination. It should be noted that the reduction in the content of clay additives in the composition of the catalyst mass (compared to example 3) reduces its elasticity and prevents the formation of blocks of cellular structure. Optimal catalytic and structural-mechanical properties of block-type catalysts in examples 1, 2, 3, calcined at temperatures of 500-800oC. the Best formability has the composition of the catalyst mass of example 2.

The method of preparation of a catalyst comprising a mixture of catalytically active metal oxides and inorganic binder additives, followed by extrusion molding in the form of blocks of honeycomb structure, characterized in that the catalytically active oxides, a mixture of oxide of iron, chromium and zinc, the components of the catalyst is subjected to wet grinding with subsequent spin on filter press to a moisture content of 28% and shaping is done on the air, followed by drying and calcination.

 

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