Abstract: A system, apparatus, and method for oxidizing methane in the exhaust gas from a lean-burn combustion gas engine in which a syngas stream comprising H2 and CO, or a combustible hydrocarbon with a light-off temperature at or below the temperature of the engine exhaust temperature, is added to and combined with the engine exhaust stream and passed through an oxidation catalyst whereupon the combustible gas oxidizes and increases the operating temperature of a platinum group oxidation catalyst sufficiently to exceed the light-off temperature of the platinum group catalyst for oxidizing methane emissions contained in the engine exhaust stream.

Abstract: An apparatus and method for attenuating sound from an engine exhaust. The relative lengths of the expansion chambers and other components within the apparatus provide a quadruple tuning effect which attenuates sound over a wide frequency range. Attenuation at higher frequencies is also increased and extended by the use of acoustically lined internal baffle tubes inside the apparatus housing.