Method for treating exhaust gas stream involves performign continuous contact of hydrogen, oxygen and nitrogen monoxide-containing effluent stream with particulate silver/aluminum oxide catalyst, and removing particulate material

摘要

Continuous contact of hydrogen, oxygen and nitrogen monoxide-containing effluent stream with a particulate silver/aluminum oxide catalyst is carried out to oxidize at least one portion of the nitrogen monoxide to nitrogen dioxide. The effluent stream is contacted with a catalytic material to oxidize nitrogen monoxide. While removing particulate material from the stored silver/alumina catalyst, the particulate silver/alumina catalyst completed its action on the heated gas stream. When temperature reaches to 250[deg] C or less, and the engine is turned off and restarted. Continuous contact of hydrogen, oxygen and nitrogen monoxide-containing effluent stream with a particulate silver/aluminum oxide catalyst is carried out to oxidize at least one portion of the nitrogen monoxide to nitrogen dioxide, and to temporarily store a bit of nitric oxide and nitrogen dioxide product of the particulate catalyst material. The primary catalyst material of particulate silver/alumina catalyst is contacted with flowing exhaust stream, and silver/alumina catalyst particles of silver or silver oxide are deposited on support particles of alumina. The effluent stream is contacted with a catalytic material containing particles of platinum group metal or several platinum group metals to oxidize nitrogen monoxide. When temperature of the exhaust gas increases, the platinum group metal catalyst is heated to a working temperature. The continuous contact of exhaust gas with each of silver/alumina catalyst and platinum group metal particles is carried out for period of engine operation. While removing particulate material from the stored silver/alumina catalyst, the particulate silver/alumina catalyst completed its action on the heated gas stream. When temperature reaches to 250[deg] C or less, and the engine is turned off and restarted. The motor passes during cold start in a lean operation and comprises effluent stream of mixture containing nitrogen monoxide, carbon monoxide, hydrocarbons, hydrogen, water, carbon dioxide, oxygen and nitrogen, in which effluent stream has an initial temperature of 75[deg] C or less, and is increasingly heated for an additional engine operation. The silver content is 0.5-10% of total content of particles of silver or silver oxide, and alumina. An independent claim is included for catalytic reactor for treating exhaust gas.