SU451458A1 - Catalyst for gas purification from nitrogen oxides - Google Patents

Description

(54) CATALYST FOR CLEANING GAS FROM NITROGEN OXIDES

one

This invention relates to catalysts for the purification of gas from nitrogen oxides, such as exhaust gas, the production of nitric acid, ammonium nitrate, a number of synthetic productions. .

A known catalyst for the purification of gas from nitrogen oxides, for example, exhaust gas of internal combustion engines, containing neodymium oxide in an amount of 0.01 to 25 wt. % carrier-alumina. Known catalyst has sufficient activity. In order to increase the catalyst activity, a real catalyst has been proposed, in which cerium oxide is taken as the rare earth metal oxide and the catalyst has the following composition: %: cerium oxide - 5-20, alky mini oxide 95-8O.

The proposed catalysaacher is intended for the purification of gases from nitrogen oxides with the formation of ammonia as a reagent and is highly active.

and selectivity in the temperature range of 350-500 ° C.

Example. 11.1 g

1.5 НО is dissolved in 6О ml Н-О and 1О ml of 50% N.

The resulting solution is impregnated with 5O g at 600 ° C for 30 minutes. The impregnated carrier is maintained at 120 ° C for 6 hours, followed by calcining at 6OO ° C for 8 hours until the salt has been completely converted to cerium oxide. The catalyst thus prepared contains 1O weight. % CEO and 9O weight. %

The specified catalyst tested on a gas mixture of the following composition, about. %: nitric oxide 0,2; ammonia 0.2-0.22; oxygen in, O; the rest is in the balance of aeot, the volumetric gas velocity is 1OOOO hour, the temperature of the test is 35 ° -50 ° C.

The degree of purification was 6-99%. Below is the degree of purification depending on temperature.

temperature, С

Cleaning degree

%

90.0

320 97.5 350 99.2 400 96.0 450 92.0 480

For comparison, a catalyst based on neodymium oxide, prepared similarly to the proposed peroxide catalyst, is taken and tested in the process of reducing nitrogen oxides with ammonia,

S p and significant npi measures. The catalyst is prepared by soaking the degree of purification,%

Cerium oxide content.

Temperature,

ki 50 g aqueous / solution of zirous neodymium concentration of 4.8% M j

at for 30 min. The impregnated carrier is dried at 120 ° C for 5 hours and calcined at 6OO ° C for 9 hours until complete decomposition of the salt to neodymium oxide. Catalysts catcher holds 4 weight. %

Catalysts based on oxide oxides and based on oxides of neodymium were prepared under the same conditions by impregnation of the carrier in solutions of the corresponding salts, followed by drying and calcination.

The test results of these catalysts showed the following activity in a mode similar to that described and are shown in the table.

Neodymium oxide content.