Abstract: The present invention relates to a compressed natural gas combustion and exhaust system comprising: (i) a natural gas combustion engine and (ii) an exhaust treatment system comprising an intake for receiving an exhaust gas from the combustion engine and a catalyst article arranged to receive and treat the exhaust gas, wherein the catalyst article comprises: a substrate having at least first and second coatings, the first coating comprising a palladium-containing alumina and/or a base-metal containing alumina and the second coating comprising a palladium-containing zeolite, wherein the first coating is arranged to contact the exhaust gas before the second coating; and, wherein the system is configured to selectively operate in: (a) a lean first mode in which sulphur is trapped on the first coating; and (b) a rich second mode whereby sulphur is released from the first coating. The present invention further relates to a method.

Abstract: An oxidation catalyst for treating an exhaust gas produced by a stoichiometric natural gas (NG) engine comprising a substrate and a catalytic material for oxidising hydrocarbon (HC), wherein the catalytic material for oxidising hydrocarbon (HC) comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve, wherein the molecular sieve has a framework comprising silicon, oxygen and optionally germanium.

Abstract: An oxidation catalyst for treating an exhaust gas produced by a stoichiometric natural gas (NG) engine comprising a substrate and a catalytic material for oxidising hydrocarbon (HC), wherein the catalytic material for oxidising hydrocarbon (HC) comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve, wherein the molecular sieve has a framework comprising silicon, oxygen and optionally germanium.