SU1009508A1 - Method of producing catalyst for synthesis of ammonia - Google Patents

Description

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This invention relates to the field of producing a catalyst for ammonia synthesis.

A known method of preparing a catalyst for the synthesis of ammonia by coagulating a mixture of iron hydroxide, aluminum oxychloride and boric acid in a kerosene / ammonia water layer, followed by drying the formed granules, calcining at 900–1300 ° C with potassium nitrate and additional calcination at 600. C (1 j.

The disadvantage of this method is the preparation of a catalyst with low activity.

The closest to the invention in its technical essence and the achieved effect is a method of preparing a catalyst for ammonia synthesis by mixing aluminum oxychloride, boric acid and an iron-containing component, coagulating the resulting mixture in a kerosene / ammonia water layer, drying and calcining the shaped granules, impregnating it with an aqueous solution potassium nitrate and additional calcination.

At the same time as the iron-containing component using iron oxyp, pre-worn in a vibrating mill or obtained by plasma chemistry method.

The disadvantage of this method is the preparation of a catalyst with low activity. So, in the synthesis of ammonia in the temperature range iiOO-550 C at a pressure of 300 at and an air flow rate of am-. The mica hydrogen mixture of 30,000 h. The yield of ammonia on the catalyst obtained in a known manner is 9.0-15.9 lO.

The aim of the invention is the preparation of a catalyst with increased activity.

The goal is achieved by the method of preparing a catalyst for ammonia synthesis by mixing an iron-containing component - iron hydroxide with iron chloride or nitrate in a weight ratio of (20-80): 1 followed by aging for 710 days, mixing aluminum oxychloride, boric acid and iron hydroxide, coagulating the mixture obtained. in a layer of kerosene / ammonia water, drying and calcining the molded granules, impregnating them with an aqueous solution of potassium nitrate with additional calcination of the catalyst mass.

Distinctive features of the present invention are the use of iron hydroxide as an iron-containing component and the mixing of iron hydroxide with iron chloride or nitrate in a weight ratio (20-80): 1 followed by aging for 24 hours before mixing with aluminum oxychloride and boric acid.

The invention makes it possible to obtain the following positive effect. The activity of the catalyst obtained by this method, expressed by the yield of ammonia, under synthesis conditions similar to the prototype, is, depending on the composition of the catalyst, 9.0-19.0 obL.

The invention is illustrated by the following examples.

Example 1. Iron hydroxide is prepared by precipitating a 10% aqueous solution of an iron salt (nitrate or chloride) with ammonia solution with vigorous stirring and pH 9. The precipitate is filtered and washed until no ions in the filtrate (NO or CE) are added. To 60 g iron hydroxide

1.2 g fe (HQ-) is added. Stir and incubate the mixture for 7-1.0 days. The resulting pseudo-salt of iron hydroxide is mixed with 0 g of aluminum oxychloride and

boric acid in the amount of 15 wt. VdOz in relation to AP203 Aluminum oxychloride is obtained by peptizing freshly precipitated at pH 10 and i 20 ° C aluminum hydroxide with hydrochloric acid

to pH k. The pseudo-sol mixture is then sent to a molding column, in which spherical granules are obtained by coagulating in a droplet in a kerosene layer and 15% ammonia water.

The formed granules are dried in air for 2 days at room temperature, then for 12 hours and at –2 hours. Then calcined at 1100 ° D and after slowly cooling to room temperature, impregnated with a 10% aqueous solution of potassium nitrate and calcined at 600 ° C until the salt is completely decomposed to potassium oxide. Catalyst

tested for activity under the following conditions for the synthesis of ammonia with a flow rate of 3000 p-1, the ratio N2: H2 25:75 vol., temperature, pressure 300 atm. 310 Comparative characteristics of the catalysts are given in table. 1. p 2. To 70 g of iron hydroxide Prim obtained in example 1, add 1, g ReСВз-6Н20, mix and maintain the mixture for 7-10 days. The resulting iron hydroxide pseudozole is mixed with 3.0 g of aluminum oxychloride and boric acid in an amount of 15 masD203 relative to Ab203. All further operations are carried out according to Example 1. The comparative characteristics of the catalysts are given in Table. 2. Example 3. To 80 g of hydroxide of iron obtained in example 1, add 1.6 g of Fe (NO3) 3 H20, stir and incubate the mixture for 7-10 days. The resulting pseudo-hydroxide hydroxide is mixed with 20 g of aluminum oxychloride and boric acid in an amount of 15 wt.% LWO with respect to. All further operations are carried out as in Example 1. The comparative characteristics of the catalysts are given in Table. 3. Example 4. To 98 g of iron hydroxide add 2 g of the ferric chloride salt ReС826Н20, mix and. maintain the mixture for 7-10 days. The formed iron sol is mixed with 2 g of aluminum oxychloride and boric acid in an amount of 15% by weight 8203, relative to. A mixture of table 1 8, lei is formed into balls in the form of hydrocarbon-ammonia method, the formed granules are dried, calcined and modified with potassium oxide. Physico-chemical characteristics of the catalyst are given in table. . Pm and me, p 5. To 98 g, of iron hydroxide, add 0.8 g of ferric chloride of OpSobloHlO, stir and maintain the mixture for 7-10 days. The resulting thixotropic suspension is mixed with 2 g of aluminum oxychloride and boric acid in an amount of 15 wt.% BgOg with respect to AP203. The mixture is formed into balls using the hydrocarbon-ammonia method. Molded granules are dried, calcined and modified with potassium oxide. Physico-chemical characteristics of the catalyst are given in table. 5. The invention makes it possible to produce catalysts with a wide range of component ratios, while the prototype allows only a certain ratio of the iron-containing component and alumina, since with a decrease in the content of alumina less than 23 wt.%, The formed granules have insufficient mechanical strength. Comparative characteristics of the catalysts obtained according to the invention and by known methods are presented in Table. 6

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Claims (1)

METHOD FOR PREPARING THE CATALYST FOR AMMONIA SYNTHESIS by mixing aluminum oxychloride, boric acid and an iron-containing component, coagulating the resulting mixture in a kerosene / ammonia water layer, drying · .:. and calcining the formed granules, impregnating them with an aqueous solution of potassium nitrate with additional calcination of the catalyst mass, characterized by the fact that, in order to prepare a catalyst with increased activity, iron hydroxide is used as the iron-containing component and before mixing aluminum oxychloride, boric acids and iron hydroxide are mixed with iron chloride or nitrate in weight ratio (20-80): 1, followed by exposure for 710 days J ^;