Preparation Of Cerium-based Catalysts For Automobile Exhaust Elimination

With the economic development,the problem of air pollution is getting worse.The sources of air pollution are mainly the combustion of fossil fuels and the emission of automobile exhaust.The elimination of nitrogen oxides(NOx)and carbon monoxide has become an urgent issue.The currently reported catalysts for the simultaneous elimination of CO and NO in automobile exhaust are mainly precious metal catalysts,and require higher reaction temperatures.This has hindered the practical application of automobile exhaust elimination to a certain extent.Therefore,it is necessary to prepare a catalyst with low cost and high reactivity for the removal of CO and NO from automobile exhaust.China's rare earth resources are very rich,and CeO2 is a good choice.Based on the good oxygen storage and release capacity of CeO2,research and development of a series of cerium-based catalysts have extremely important practical application value.In this study,we design and prepare a PdO-CeO2-OMS ternary oxide composite for selective catalytic reduction of NO(NO-SCR)by CO as reducing agent.The PdO-CeO2-OMS composite is analyzed by a serial of technology,such as scanning transmission electron microscopy(STEM)with energy dispersive X-ray detector(EDX),powder X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and temperature-programmed reduction(TPR).XPS and H2-TPR present the Pd clusters mainly comprise of Pd?O species.The PdO-CeO2-OMS composite shows excellent catalytic performance.The presence of PdO clusters largely improve the catalytic performance.(NO+CO)-TPD experiments suggest the CO molecules are selectively adsorbed and activated over the PdO sites.And the NO-SCR should occur at interfacial perimeter of PdO particles and CeO2-OMS(indication by XPS results)and the selectivity is largely tailored by the CeO2-OMS supports.The PdO-CeOZ-OMS catalysts exhibit significant stability and H2O tolerance during the NO-SCR tests.This study may offer some strategies to design new metal cluster catalysts for the NOx-SCR process in a membrane reactorIn this study,we prepared a series of cerium-copper catalysts by changing the type of cerium source,precipitant and reducing agent,and optimized the synthesis time and calcination temperature of the cerium-copper catalyst.Under anaerobic conditions,the catalytic activity of selective reduction of NO with CO as reducing agent was investigated,and a CuO-Ce(CO3)2O catalyst with excellent performance was obtained(100%NO and CO convension and full N2 selectivity at 250 ?).CuO-Ce(CO3)2O catalyst still maintains high reactivity in the presence of SO2 and water vapor.The morphology of the catalyst was observed to be fusiform by a transmission electron microscope.The cerium-copper catalyst has high reaction activity and low cost,and has broad market prospects.