SU925380A1 - Catalyst for oxidation of sulphurous acid anhydride - Google Patents

Description

as a carrier, silicon nitride. This makes it possible to increase by 14–20% the specific activity of the catalyst in comparison with the prototype.

The catalyst is prepared by mixing silicon nitride with an alkaline solution of potassium vanadate, silica gel, ethyl silicate and sulfuric acid at pH 4-5. The proportion of silica in silica injected in the form of ethyl silicate is 10-50 May. % The contact mass obtained in the form of granules, calcined at 540-620 ° C for 2-4 hours.

The invention is illustrated by the following examples.

Example 1. Silicon nitride powder in an amount of 100 g is mixed with 54 g of silica hydrogel (humidity 75%) and the mass is thoroughly mixed. 132 g (102 ml) of vanadate liquor (VaOs concentration 159 g / l, molar ratio K2O / V2O5 3: 1) are added to the mixture and then 23.2 g (15.5 ml) of sulfuric acid solution ( 1: 1 vol.), Bringing the pH of the pulp to 4-5, then pouring 32.4 g (30.8 ml) of ethyl silicate (SiOa content 40-41 May.%). The mixture is thoroughly homogenized. The contact mass is dried to a moisture content of 30%, extracted. The granules are dried at 110-120 ° C for 3 h and calcined at. 550 ° C for 2 hours. The resulting catalyst contains, May. %:

VsOs9.0

K2014,0

SiOa15,0

SisNi62,0

Example 2. Analogously to Example 1, a contact mass of 100 g of silicon nitride is prepared; 52 g of silica hydrogel; 40.3 g (35 ml) of vanadate liquor (VsOs concentration 143 g / l, molar ratio K2OA2O5 2.03: 1); 5.3 g (3.5 ml) of sulfuric acid (1: 1 vol.) And 3.45 g (3.25 ml) of ethyl silicate. The catalyst granules are dried at 110-120 ° C for 6 h and calcined

Comparative data on the catalytic activity of catalyst samples

at 580 ° C for 2 hours. Received

The catalyst has a composition, May. %:

4.0

42

11.5

80.3

Example 3. Analogously to example I, a contact mass of 100 g of silicon nitride is prepared; 24.8 g of silicic acid hydrogel; 59.0 g (51.4 g) of vanadate liquor (V2O5 concentration 146 g / l, molar ratio K2O / V2O3 2: 1); 7.95 g (5.3 ml) of sulfuric acid (1: 1 vol.) And 3.4 g (3.2 ml) of ethyl silicate. The granules are dried at 110 ° C for 4 hours and calcined at 600 ° C for 2 hours. The catalyst is composed in May. %:

5.9

6.1

6.0

82.0

The activity of the catalysts is tested in a flow circulating unit at 485 ° C, concentration of F3 11% by volume. % and Og 17.1 vol.% in the initial reaction mixture and at a space velocity for the diffusion region of about 1.4 s and a kinetic 2.6.

The values of the reaction rate constants obtained in the diffusion region on grains of industrial size, or the values of the specific rate constants obtained in the kinetic region are taken as a measure of activity. The heat resistance is estimated by the change in the rate constants after the catalysts are treated in a current of the ionic mixture at 700 ° C for 10 hours. The values of the specific rate constants are determined by relating the rate constants measured in the kinetic region to the corresponding values of the specific surface of the catalyst samples.

The test results are presented in the table.

As can be seen from the table, the specific reaction rate constants for the catalyst based on silicon nitride are 14–20% higher than those for the catalyst based on marshalite.

The thermal stability of the catalyst according to the invention is at the level of a known catalyst. After thermal testing, the reduction of the rate constants for it is 5–13%, while for industrial catalysts, SVD and BAS under similar conditions is 27–35%, i.e., the total increase in heat resistance is 14–30% for the proposed catalyst.

Claims (3)

1. Mukhlenov I.P. Catalysts technologists, L., “Chemistry, 1974, p. .154. 2. Mukhlenov I.P. Catalysts technologists, L., “Chemistry, 1974, p. 116. 3. USSR author's certificate number 599833, cl. 01 J 23/22, 1975 (prototype).