The catalyst chromium-nickel complex gas purification from nitrogen oxides and carbon monoxide

 

(57) Abstract:

The invention relates to the protection of the environment from toxic gas emissions, namely the catalysts for purification of exhaust gases of internal combustion engines from nitrogen oxides and carbon monoxide. Describes the catalyst chromium-Nickel complex gas purification from nitrogen oxides and carbon monoxide containing media on the basis of silica is Aerosil coated components, and the composition of the media introduced the addition of bentonite clay with a particle size of less than 110-3mm, and the ratio of the components is, wt.%: Nickel oxide 5,08? 7.04 baby mortality; chromium oxide 9,6-11,5; silicon dioxide 68,12-age of 65.17; clay bentonite 17,2-16,29. The catalyst allows thanks reseparate the structure of media to produce effective cleaning of exhaust gases from nitrogen oxides NOxand carbon monoxide CO for 300 hours table 2.

The invention relates to catalysts for purification of gas emissions from monoxide, carbon and nitrogen oxides, such as exhaust gas of internal combustion engines, gas emissions from thermal power plants etc.

A known catalyst (see and.with. 1132962,barely. The cleaning process is conducted at a temperature of 640-740oC in the presence of reducing agents monoacid carbon and oxygen.

This catalyst provides a high degree of purification for 6 hours, then the efficiency drops sharply, the service life of the catalyst is small - through 96 hours, the degree of purification is reduced to 24%.

Nearest to offer the technical essence is the catalyst for purification of gases from nitrogen oxides from internal combustion engines (see and.with. 1447393, M CL 01 J 23/26, 23/36, published in BI 48 - 1988).

The catalyst is a faience carrier with a specific surface area 60-128 m3/g, which caused the oxides of Nickel and chromium in the following ratio, wt.%:

Nickel oxide is 5.5 to 8.3

The chromium oxide - 10,4-15,2

Faience media - Rest

This catalyst is designed for cleaning of gases from nitrogen oxides and has sufficient efficiency at a temperature of 400oC.

Its production requires high energy costs in the preparation of the molding material - stirring for 4-5 hours, drying and calcination of the molded pellets at temperatures 250oC and 1150oC sootvetstvenno snijaetsa.

The aim of the invention is to develop a catalyst for the efficient purification of exhaust gases of internal combustion engines from nitrogen oxides and carbon monoxide.

The authors propose the catalyst for purification of exhaust gases of the engines internal combustion oxides of nitrogen and carbon monoxide containing media based on silicon dioxide coated components, and the composition of the media entered the bentonite clay with a particle size less than 10x10-3mm, and the ratio of the components is, wt.%:

Nickel oxide - 5,08? 7.04 baby mortality

The chromium oxide - 9,6 - 11,5

Silicon dioxide (Aerosil) - 68,12 - age of 65.17

Clay bentonite - 17,2 - 16,29

Distinctive features of the invention are used as the inorganic binder in the carrier bentonite clay Watches-Yarskaya field with a particle size of less than 1x10-3mm, and the ratio of carrier components, wt.%:

Nickel oxide II - 5,08? 7.04 baby mortality

Oxide of chromium III - 9,6 - 11,5

Silicon dioxide - 68,12 - age of 65.17

Clay bentonite - 17,2 - 16,29

In the composition of the carrier include Aerosil - dispersed silica with a specific surface area of 300 m3/g, an average size of frequent the em to create reseparate structure of the carrier with a specific surface area of 120-140 m2/g and a predominant pore of 0.015 μm. The basis of the medium - Aerosil grades a-300 provides a high specific surface area, mechanical strength and thermal stability with the addition of inorganic binder is bentonite clay Watches-Yarskaya field. Organic binders, providing the necessary rheological properties of the moldable mass is an aqueous solution of polyvinyl acetate dispersions.

Catalytic mass containing precious metals, the carrier is introduced by impregnation with solutions of salts of transition metals - chromium (III), Nickel (II) with subsequent drying and calcination.

The catalyst efficiency was evaluated according to the degree of purification of exhaust gases of the internal combustion engine from carbon monoxide (CO) and oxides of nitrogen (NOx) on the stand, created on the basis of universal compressor station UKS-400V. Power unit on the stand is a diesel engine YAM 3-236. The presence of the compressor allows to obtain load characteristics of the modes close to the characteristics of diesel cars in operation on the roads.

Site purification of exhaust gases with the catalyst test is a reaction apapane warming up of the catalyst is regulated by a rheostat.

The presence of NOxand CO in the exhaust gas, the concentration and temperature before and after the catalyst is recorded by detector type IMR 3000 RUB.

Studies of the catalyst was carried out at idle and load operation of the engine. When testing at idle for withdrawal of catalyst on the mode has been heated catalyst (spiral). In both cases, the catalyst is filled in a glass of displacement ye= 5,610-5m3.

At idle the gas before the catalyst had a temperature 95100oWith the load mode 220230oC. the gas Flow through the catalyst was measured by volumetric method and changed within 0,180,09 m3/h, while the flow rate was respectively 30005000 h-1. The concentration and the temperature of the gases were measured before and after the catalyst. The degree of purification of exhaust gases from CO and NOxdefined by the change of the composition of the effluent gases in relation to the composition of the incoming gas.

Example. Prepare media (silicon dioxide) Aerosil grades a-300, clay Watches-Yarskaya and polivinilatsetatnoj dispersion (PVAD) density () of 1.01 g/m3. To obtain a molding material to 18 g of Aerosil was added 4.6 g of clay, smelecom formed into spherical granules with a diameter of 5 mm The granules are dried for 24 hours at a temperature of 205oC and calcined for 30 minutes at a temperature of 900oC. Prepared medium was incubated for 24 hours at a temperature of 205aboutWith and impregnated with a catalytic material containing a 10% aqueous solution of Nickel nitrate II and 25% aqueous solution of chromium nitrate III, dried for 24 hours at a temperature of 205oC and calcined in air for 2.5 hours at a temperature of 550oC. the resulting catalyst has a composition in mass %: NiO - Of 5.89%, CR2O3- 10,4%, the rest of silica and clay.

To determine the degree of exhaust gas purification catalyst is placed in a tubular reaction apparatus and passed through it, the output gas of the internal combustion engine with a bulk velocity 30005000 h-1containing nitric oxide SPOx= 1254 ppm and carbon monoxide WITHCO= 1170 ppm at a temperature of 230oWith on load operation of the engine, and CNOx= 198 ppm andCO= 770 ppm at a temperature of 100oWith the idling operation of the engine.

The results of the test catalyst at idle and load conditions of the engine are presented in tables 1 and 2 respectively.

The test results of the mine on its surface. The necessary temperature for the beginning of the redox catalytic process is 265oC at idle engine operation, and the degree of purification of exhaust gases from WITH was 78%, NOx- 10%, temperature is achieved at the expense of Electrophotography catalyst.

At a temperature of 320oC the degree of purification from CO was 86%, NOx- 39%. Further, if the heating system is a decrease in the temperature of the gas after the catalyst, and the degree of gas purification catalyst increases and at a temperature of 180oC is 90% of the CO and 55% of the NOx. At temperatures below 165oC is a decrease in the degree of purification of exhaust gases, therefore, suitable electric heating catalyst.

Testing of the catalyst at idle engine operation was carried out for 6 hours.

In the discharge mode of operation of the engine the necessary temperature redox catalytic process is 280oWith the degree of purification of exhaust gases from CO - 71%, NOx- 67%. The degree of purification of the exhaust gas remains stable from SB (80-82%), NRx(70-73%) with little change in temperature is appointed for purification of exhaust gases of the internal combustion engine from nitrogen oxides and carbon monoxide in contrast to the prototype, applicable in respect of oxides of nitrogen.

The use of media with high specific surface 120-140 m2/g derived from inorganic substances Aerosil grades a-300 - highly dispersed silicon dioxide and particle size of 52010-12mm and inorganic binders - montmorillonite (bentonite) clay Watches-Yarskaya field with a particle size of less than 1x10-3mm High specific surface area components of the medium and particle size allow you to create reseparate the structure of the catalyst.

The media of the proposed catalyst is prepared by mechanical mixing of the components for 0.5 h, and firing the formed and dried granules at a temperature of 900oC for 0.5 h, resulting in lower energy consumption compared to production of the known catalyst.

The catalyst provides the cleaning efficiency of the exhaust gas from the NOxand WITH over 300 hours.

The catalyst chromium-Nickel complex gas purification from nitrogen oxides and carbon monoxide containing media on the basis of silica is Aerosil coated components, characterized in that chinoserie components, wt.%:

Nickel oxide - 5,08? 7.04 baby mortality

The chromium oxide - 9,60 - 11,50

Silicon dioxide - age of 65.17 - 68,12

Bentonite clay - 16,29 - 17,20 and

 

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