초록 ▼

The invention relates to reduction of nitric oxide in exhausts from hydrocarbon burning engines. The nitric oxide is reacted with ammonia over a first catalyst and then the excess ammonia is reacted with oxygen present in the exhaust gas over a second catalyst. The resulting effluent stream has grea

The invention relates to reduction of nitric oxide in exhausts from hydrocarbon burning engines. The nitric oxide is reacted with ammonia over a first catalyst and then the excess ammonia is reacted with oxygen present in the exhaust gas over a second catalyst. The resulting effluent stream has greatly reduced nitric oxide content without having an objectionable content.

대표청구항 ▼

A method of removing nitric oxide from a hydrocarbon burning engine exhaust stream, the engine operating under varying load conditions from a high load to a low load wherein the exhaust stream temperature varies from a high of about 800°C. to a low of about 200°C., comprising: contacting a combusted

A method of removing nitric oxide from a hydrocarbon burning engine exhaust stream, the engine operating under varying load conditions from a high load to a low load wherein the exhaust stream temperature varies from a high of about 800°C. to a low of about 200°C., comprising: contacting a combusted gas stream comprising nitric oxide and oxygen with ammonia, the contacting over a first catalyst bed having a catalyst comprising a zeolite which catalyzes a reductive reaction of ammonia with nitric oxide, the amount of ammonia from about 0.5 to about 2 times the stoichiometric amount for the reductive reaction of ammonia with nitric oxide, the contacting at a temperature between about 200°C. to about 800°C., the first catalyst bed retaining ammonia when the temperature is above about 315°C. and desorbing a portion of the ammonia at a temperature from about 200°C. to about 315°C., to form an effluent gas stream having oxygen, a reduced amount of nitric oxide content, and having the desorbed portion of ammonia when said contacting is at a temperature from about 200°C. to about 315°C.; and contacting said effluent gas stream with a second catalyst bed comprising a porous solid carrier having a catalytically active oxidation catalyst metal disposed thereon which is sufficiently active to catalyze the oxidation of the desorbed portion of ammonia to form a substantially nitric oxide free and ammonia free exhaust stream.