Electrochemical-catalytic conversion for simultaneous NO x and hydrocarbons emissions control of lean-burn gasoline engine
Electrochemical-catalytic conversion via the electrochemical-catalytic cell (ECC) is effective at 400°C for simultaneous NOx and hydrocarbons emissions control of lean-burn gasoline engine without consuming any reductant. The NO reaction is direct NO decomposition. The NOx to N2 rate over the cathode of the ECC can be three orders larger than those over conventional oxide catalysts for NO decomposition. In the high NOx concentration region, the NO conversion increases with increasing NOx concentration; this characteristic allows the engine to be operated at high enough temperature with excess oxygen to result in maximum fuel efficiency. In the low NOx concentration region, the NO conversion also increases with decreasing NOx concentration; this characteristic enables complete conversion of NO and thus can result in zero NOx emission. The NO conversion increases with decreasing temperature, at least till 400°C. Higher oxygen concentration is beneficial to both the NO conversion and the hydrocarbons oxidation to result in zero pollution.