SU1674954A1 - Method of producing catalyst for cleaning exhaust gases - Google Patents

Abstract

This invention relates to catalytic chemistry, in particular to the preparation of a catalyst for the purification of exhaust gas. The goal is to increase thermal stability and catalyst activity. The preparation is carried out by impregnating the fibrous mullite silicon-soluble material with copper acetate solution. The process is carried out followed by drying and calcining at 250-400 ° C. Preferably, the impregnation is carried out with a solution of copper acetate, providing the amount of copper oxide in the catalyst 4-6 wt.%. 1 hp f-ly, 3 tab.

Description

The invention relates to the field of air purification from harmful organic impurities, in particular, to methods for producing a catalyst for the deep oxidation of harmful organic impurities and carbon monoxide in exhaust gases.

The aim of the invention is to obtain a heat-resistant, active catalyst, for which the fiber is used as a carrier, mullite-silica material, and the impregnation is carried out with a saturated solution of copper acetate directly in the catalytic reactor.

Example 1. In 100 ml of distilled water is dissolved 0.4 g of copper acetate. A weighed portion in 100 ml of mullite silicon-fiber fibrous material of the mark MKRR-130 is placed on the grid of the thermo-catalytic reactor and calcined at 1000–1300 ° C in air flow for 20–30 min. Cool the reactor to 20-30 ° C, the carrier sample is impregnated by capacity

prepared solution of copper acetate, which irrigate the carrier layer for 15-20 minutes. Drying of the catalyst is carried out in a reactor at 100-120 ° C until the material turns blue from black, after which the catalyst is calcined at 400 ° C for 4 hours in a stream of air. Layer-by-layer chemical analysis of the obtained sample showed a uniform distribution of copper oxide over the entire volume of the fibrous mullite-siliceous material. The total content of copper oxide in the sample 3 wt.%.

The catalytic activity of the samples obtained is determined in a dynamic flow setup with respect to the model reaction of the complete oxidation of phenol and carbon monoxide with oxygen. For the tests, 6 ml of catalyst was taken, the initial concentration of phenol and carbon monoxide was 5 mg / l, the volumetric rate of the reaction mixture was 10,000.

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Examples 2-5. Similar to example 1, but the mullite-silica material is impregnated with a solution of acetic copper in terms of copper oxide 4, 5, 6 and 7 wt.%, Respectively.

The temperatures of 100% conversion of phenol and CO on the obtained catalysts, which characterize their activity, are given in Table 1 (for comparison, data on the catalytic activity of an industrial alumina oxide catalyst sample are given).

From table 1 it can be seen that the complete combustion of phenol and carbon monoxide to carbon dioxide and water occurs on the catalysts of the proposed method with the content of copper oxide 4-6 wt.% At temperatures 30-50 ° C lower compared to the aluminum-oxide catalyst containing 8-10 wt.% CuO. Without a supported catalyst, the oxidation of phenol at a noticeable rate begins only at temperatures above 750 ° C.

Table 2 shows the data characterizing the thermal stability of the catalyst, e. the degree of preservation of activity during thermal overheating.

Table 2 presents the results of the study of the catalytic activity of contacts subjected to aging at 750 ° C. As can be seen from the above data, catalysts deposited on and on ceramics (Raschig rings) reduced the activity in the oxidation reaction of phenol at 400 ° C, respectively, by 20 and 35%. This is caused by sintering the catalyst with alumina. The activity of the copper oxide catalyst on the mullite-siliceous fiber material does not decrease even after 10 hours of contact work at 550 ° C. This is due to the fact that a new type of carrier remains elastic and there is no sintering of the catalyst, since the fibers of mullite from the surface are vitrified with silicon oxide, which prevents the interaction of copper oxide with aluminum oxide, which prevents the decrease in activity.

The use of copper acetate as an impregnating solution in addition to simplifying the technology for producing a catalyst and eliminating oxides of nitrogen and ammonia from flue gases allows copper oxide to be applied as a highly dispersed phase on the surface of mullite-silica fibers. two large ligands of organic (acetic acid) compared with ligands (anions) of nitric or carbonic (copper carbonates) acids. With

In such a configuration of acetate, chemisorbed copper oxide crystals appear to be separated by active centers of alumina, as a result of which the impregnated

the desorption of acetic anhydride and a significant reduction in its concentration in the catalyst calcining off-gases.

Table 3 presents the data characterizing the thermal stability of copper oxide deposited on the fibers of mullite-mineral material in the oxidation of phenol at 400 ° C and a space velocity of 10,000 hours after heat treatment

at 750 ° C for 10 h from the proposed impregnating solutions.

As can be seen from Table 3, the catalyst obtained from copper acetate retains a high activity, whereas copper oxide.

obtained from solutions taken for comparison, reduces activity by 30%.

In addition, in the processes of preparation of catalysts based on the use of copper nitrate or ammonium carbonate complex of copper, a significant amount of harmful substances is released during calcination. In the method based on copper acetate, it is significantly less. Thus, a more environmentally friendly method has been proposed in comparison with the known method of obtaining a highly active and thermostable supported catalyst that has a twice lower content of copper oxide.

Claims (2)

1. A method for preparing a catalyst for purifying waste gas from harmful organic impurities and carbon monoxide by impregnating the carrier with a solution of copper salt subsequent drying and calcining at 250-400 ° C, characterized in that, in order to increase the thermal stability and activity of the catalyst, fibrous mullite silica material is used as the carrier and copper acetate is used as the copper salt. 2. A method according to claim 1, characterized in that the impregnation is carried out with a solution of copper acetate, providing an amount of copper oxide in the catalyst of 4-6 wt.%. Table 1 4-6 65.0 20-3020 50-60 20 4-64-6 26.08-10 9-13 15-25 20 8-136-8 table 2 Table 3 Acetic Anhyd-10 Reed 50 Couples Nitrogen oxides 400 kg per ton - 10 catalyst Ammonia 330 0 65