RU1626495C - Method to produce catalyst for ammonia oxidation second stage - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: catalyst is produced by plasma-chemical treatment of dispersed suspension of magnesite slime (concentrated nitric acid production waste) with following hardening in the open air under temperature of 250 300 C, separation of catalyst mass from gas stream and moulding. The conditions provide better activity and thermal stability of catalyst, that on second stage of ammonia provides its conversion 96.8 against 95,6 In the case, after temperature drop from 900 to 800 C activity is 97 against 96.7% EFFECT: increased activity and thermal stability of catalyst. 1 tbl

Description

 The invention relates to methods for producing catalysts, in particular a catalyst for the second stage of ammonia oxidation.

 The purpose of the invention is the preparation of a catalyst with increased activity and thermal stability through the use of new raw materials and the introduction of additional operations.

 The invention is illustrated by the following examples.

PRI me R 1. A suspension of magnesite sludge containing 10% of the solid phase through the nozzle is directed with a specific flow rate of G / N 0.7 kg / kW to a plasma chemical reactor with a mass-average temperature of the plasma stream of 3300K. In a plasma chemical reactor during a residence time of about 0.2 s, the formation of a finely dispersed catalytic active powder occurs. In the quenching chamber, installed directly under the reaction channel of the plasma chemical reactor, the dust-gas mixture is quenched with air up to 300 ^° C. Cooled to 130 ^° C in the connecting pipelines, fine-dispersed oxide powder is collected on the filter, unloaded, mixed with graphite and tableted. The obtained catalyst samples are tested in a laboratory setup for determining the activity of ammonia oxidation catalysts at an air mixture flow rate of 740 l / h and an ammonia content of 10-10.5 vol. space velocity 30000 h ^-1, a temperature of 800-900 ^{° C} and atmospheric pressure. As the catalyst for the first stage using one platinum mesh.

 PRI me R 2-5. Carry out similarly, changing the temperature of quenching.

 PRI me R 6 (comparative).

The suspension magnesia slurry was dried at ¹²⁰ ° C to a moisture content of 3-4% and calcined ^at 800 ^° C for 4 hours. The batch was milled in a ball mill to a particle size of 50-100 microns and tabletted.

 The test results of the catalytic activity of the samples in examples 1-6 and the prototype method are given in the table.

EXAMPLE Example s 1-3 show that quenching dust-gas mixture to ^about 250-300 C catalyst samples have higher thermal stability and activity than the catalyst samples prepared according to the prior art.

With a quenching temperature lower than 250 ^C. (Example 4) or above ^about 300 C (Example 5) thermostability and activity of the catalyst is reduced.

 The catalyst sample prepared according to example 6 has very low activity and thermal stability.

The advantage of the proposed method is to obtain a catalyst with increased activity. For example, at 900 ^{° C} and atmospheric pressure, the degree of conversion of ammonia 96.8% (95.6% for the prior art). Increasing the thermal stability shows higher catalyst activity after overheating, e.g., activity of the sample prepared by the inventive method, after reducing the temperature from 900 to 800 ^{° C} is 97.0% (96.77% prototype).

Claims (1)

METHOD FOR PRODUCING A CATALYST FOR THE SECOND STAGE OF AMMONIA OXIDATION BY PLASMA CHEMICAL PROCESSING OF A SPRAYED SUSPENSION OF IRON-CONTAINING MATERIAL followed by separation of the catalyst mass from the gas stream and its molding, characterized in that, in order to obtain a catalyst with increased activity and thermal stability, magnesite is used as a raw material. concentrated nitric acid and after plasma chemical treatment, the catalyst mass is subjected to air quenching at 250 300 ^o C.

Images