Johnson Matthey Public Limited Company

Valerie Marie Renee Houel

Raj Rao Rajaram

Stephen Poulston

Stanislaw Edmund Golunski

Stephen David Pollington

Athanasios Tsolakis

Andrea Hawkings

David William James

The present invention relates to a method of reducing coking over a Ag/AlOhydrocarbon selective catalytic reduction catalyst in an exhaust stream of a lean burn internal combustion engine, the exhaust stream including hydrocarbon and NO. The method includes controlling the hydrocarbon to molar NOratio 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.

[object Object]

A catalyst structure for treating exhaust gas from a lean burn internal combustion engine comprises a substrate monolith comprising a lean NOcatalyst (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.

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Royston, United Kingdom

Valerie Marie Renee Houel