SU417978A1 - Process for producing nickel-alumino-chrome catalyst - Google Patents

Description

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The invention relates to methods for producing a nickel alumochromic catalyst, widely used in industry for hydrogenation processes, gas purification from oxygen and oxygen-containing substances, as well as for methanation of carbon monoxide.

A method is known for producing a nickel alumochromic catalyst by treating a paste with a solution of chromic anhydride prepared from powdered basic nickel carbonate and aluminum hydroxide, followed by drying the catalyst mass, calcining, tabletting, and reconstituting. The known method allows to obtain a catalyst with high catalytic activity in the reactions of hydrogenation of organic compounds, gas purification from oxygen and oxygen-containing compounds in the process of methane carbonation. However, this catalyst does not have high mechanical strength.

In order to obtain a nickel alumochromic catalyst with high mechanical strength, it is proposed to treat the paste prepared from powdered basic nickel carbonate and aluminum hydroxide with a solution of chromic anhydride, followed by drying the catalyst

mass, calcination, tabletting, and recovery.

But to the proposed method, the starting components of the catalyst and / or the calcined catalyst mass are disaggregated. The powdery components of the catalyst can be disintegrated by grinding.

The initial powder components of the nickel alumochromic catalyst consist of nervous aggregates (intergrowths) of particles reaching sizes up to iUU microns, which significantly reduces the density of the catalyst during its preparation. Grinding — although it somewhat increases the strength of the catalyst, does not allow one to completely get rid of the aggregates, since it is accompanied by intensive formation of secondary aggregates.

But the proposed method of particle aggregates is destroyed along with grinding or instead of it in the initial powder components and / or in the calcined catalyst mass by disaggregation - mechanical processing of powders and powders that ensure destruction of the primary aggregates while reducing the secondary aggregation characteristic of grinding. The specified parameters can be achieved in vibratory mills with a small diameter of working tanks or in a tube disassembler of continuous action. In existing vibratory mills of periodic operation, disaggregation can be achieved at maximum frequencies and minimum amplitudes of oscillations by loading and periodically re-sowing the norm-shaped components or catalyst mass every 30 seconds after 2 minutes of continuous processing. In a tube disaggregator, disaggregation is achieved by continuous loading of powders from the brewer and continuous unloading of disaggregated material.

This method allows to obtain a catalyst with high mechanical strength and higher chemical homogeneity. The deviation of the nickel content from the average value — for catalyst tablets when disaggregating only one component of the catalyst — aluminum hydroxide — ranges within ± 13 wt. % With the disaggregation of both comioents, chemical homogeneity increases and becomes equal to ± 4 wt. % A catalyst with chemical homogeneity of ± 28 wt. %

Disaggregation can significantly reduce the duration of mechanical processing of powder-like components or catalyst mass, for example, from 10-30 hours for grinding mode to 1-30 minutes during disaggregation.

The proposed catalyst has a catalytic activity, for example, in carbon monoxide methanation reactions, not

the activity of the catalyst, which was obtained by the well-known method, and in some cases even exceeds it. Example 1. For the prepared catalyst, aluminum hydroxide is taken, which is disaggregated continuously for 1.5 minutes in an eccentric quadruple NIPPMM with a drum capacity of 100 cm at a frequency of 50 Hz and an amplitude of 2 mm (balls of hard alloy VK-6 are loaded into the mill diameter 4-5 mm). Then, a pasty mixture of 316 g of disaggregated aluminum hydroxide and 256 g of basic is prepared in a mixer.

nickel carbonate and water, which is treated with a solution of chromic anhydride (0.30 g of Cr 2 O 3 per ml).

Pasta dried Iri 100-130 ° C and calcined at 450 ° C. The finished catalyst mass is mixed with graphite and tableted in a diameter of 6 mm and a height of 5 mm.

In tab. 1 shows the results of tests of catalysts prepared by the proposed (sample 2) and known (sample 1) methods for mechanical strength during crushing but rib; chemical homogeneity of the tablets, characterized by a deviation of the content of the nangel from the average value; the catalytic activity in the methanation process of 1.0% CO in hydrogen, determined by the minimum temperature at which the residual content of carbon monoxide does not exceed 0.001% at a pressure of 1 atm and a space velocity of 20,000 H-1.

Table 1

Example 2. A catalyst (sample 3) was prepared as in example 1, but both powdered components were coagulated (basic nickel carbonate and aluminum hydroxide) to disaggregate. The mixture of powders disaggregated in example 1 for 15 min, with the first 2 min processing

lead continuously, in the subsequent time - with unloading and reseeding every 30 s.

In tab. 2 shows the results of testing the catalysts prepared by the proposed (sample 3) and known (sample I) methods,

table 2

Tl p and me 3. The catalyst (sample 4) is prepared according to example 1, but only prokalein} catalyst mass is disaggregated. Sample 5 is also prepared in accordance with Example 1, but both the initial aluminum hydroxide and the calcined catalyst mass are disaggregated. The calcined masses of samples 4 and 5 disaggregate continuously for 30 seconds.

Claims (1)

Invention Formula The method of producing a nickel alumochromic catalyst by treating a paste with a solution of chromic anhydride prepared from powdered basic nickel carbonate and aluminum hydroxide, followed by drying the catalyst mass. In the table. 3 shows the results of tests on the mechanical strength of the catalyst tablets prepared by the proposed (samples 2, 4 and 5) and known. (Sample 1) methods. At the same time, the initial and powder-like components of sample 1 and 4 are not disaggregated, and in samples 2 and 5, the a. Seed hydroxide is disaggregated for 1.5 minutes. Table 3 , calcination, pelletizing and reconstitution, characterized in that, in order to obtain a catalyst with high mechanical strength, the initial powder components of the catalyst and / or the calcined catalyst mass are disaggregated.