摘要:
The present invention relates to a method of reducing coking over a Ag/Al2O3 hydrocarbon selective catalytic reduction catalyst in an exhaust stream of a lean burn internal combustion engine, the exhaust stream including hydrocarbon and NOx. The method includes controlling the hydrocarbon to molar NOx ratio of the exhaust stream so as to be within certain limits at certain temperatures. An exhaust system for a lean burn engine suited to the above method, and a lean burn internal combustion engine, or a vehicle or stationary power source including such an exhaust system are also included.
摘要翻译:本发明涉及一种在稀燃内燃机的废气流中的Ag / Al 2 O 3选择性催化还原催化剂上还原焦化的方法,所述废气流包括烃和NOx。 该方法包括在某些温度下控制烃与排气流的摩尔NOx比以达到某一极限。 还包括适用于上述方法的稀薄燃烧发动机的排气系统,以及稀燃燃烧内燃机或包括这种排气系统的车辆或固定动力源。
摘要:
A catalyst structure for treating exhaust gas from a lean burn internal combustion engine comprises a substrate monolith comprising a lean NOX catalyst (LNC) composition associated with at least one partial oxidation catalyst (POC), wherein the LNC composition is selected from the group consisting of: (a) silver or a silver compound supported on alumina; and (b) at least one metal selected from the group consisting of copper (Cu), iron (Fe), cobalt (Co) and cerium (Ce) supported on at least one zeolite, and wherein the at least one POC is selected from the group consisting of: (i) a bulk oxide, a bulk composite oxide or a bulk mixed oxide comprising at least one metal selected from the group consisting of manganese (Mn), iron (Fe), cerium (Ce) and praseodymium (Pr); and (ii) at least one of rhodium (Rh) and palladium (Pd) disposed on at least one inorganic oxide support.
摘要:
A method to improve NOx reduction in diesel engine exhausts by selective catalytic reduction using reductants comprising hydrocarbons, comprising passing the exhaust gases through a series of zones, said zones comprising a first zone in which a first catalyst is located that promotes HC SCR, to yield a first product gas; a second zone through which the first product gas is passed and in which a second catalyst is located that promotes the H2-promoted HC SCR reaction to produce a second product gas and a third zone through which the second product gas is passed and in which a third catalyst is located that promotes CO/H2 SCR to yield a final, NOx-depleted, exhaust gas, and admixing a reformate gas comprising CO and H2 with one or more of the exhaust gases, the first product gas and the second product gas. The use of the series of catalysts offers a sound alternative to urea-based SCR, without requiring a source and storage of urea.