Hiroyuki Ohtsubo

Oxidation Catalysts for Natural Gas Engine Operating under HCCI or SI Conditions

Oxidation catalyst performances are studied under HCCI (Homogeneous Charge Compression Ignition) and SI (Spark ignited) conditions using a model gas reactor and with natural gas fuelled HCCI and SI engines. The characteristic emissions of HCCI engines are high levels of CO and hydrocarbons, and temperatures as low as 120°C. Conventional oxidation catalysts typically light off at around 200°C, well above these temperatures. The oxidation catalyst for a HCCI engine is required to be active at low temperature, and be durable. Test results will be shown for bench-scale experiments for a series of catalyst formulations. Some catalyst formulations show excellent performance. The HCCI-tailored catalyst exhibits complete conversion of CO under HCCI engine emission conditions with various loads. Under SI conditions, high conversion efficiencies are observed for methane and non-methane hydrocarbons.