Title : A study on simultaneous reduction of CH4 and NOx of NGOC/de-NOx catalysts for CNG buses
Abstract:
Natural gas is a clean fuel that discharges almost no substance contaminating the air. It has mainly been used as the primary fuel source for the CNG (Compressed Natural Gas) bus. Application of natural gas, with many advantages as a fuel, is anticipated to spread more widely, thanks to the rich deposit of shale gas and innovative drilling technologies and its stabilized price. However, CH4 is one of the culprits of greenhouse effect and its impact is 23 times greater than CO2 of the same mass. As of now, laws require the city bus to use CNG fuel, the primary content of which is CH4. A currently commercialized after-treatment system for reducing CH4 and NOx for CNG buses is run by a theoretical air-fuel ratio and uses a three-way catalyst. Operation in a theoretical air-fuel ratio involves deterioration of fuel-efficiency and more emission of CO2, while the after-treatment system of a lean air-fuel ratio type, increases in cost and difficulties in installation, due to the size of the catalyst unit. This study targets developing a NGOC/LNT+NGOC/SCR combined unit for a simple “one canning two brick system” that can simultaneously reduce the emission of CH4 and NOx for the CNG bus, in response to post Euro 6 emission regulation, which will be challenging and make this study more meaningful. This study is mainly focused on identifying the loading amount of precious metals, additive catalysts, loading amount of washcoat and stirring time and types of substrates, related with improvement of de-CH4/NOx performance.
