Preparation And Catalytic Properties Of Metal Modified Ni-based Composite Oxides

Carbon monoxide(CO)and nitric oxide(NO)are two major atmospheric pollutants.With the rapid development of China's industry,and the increasing number of motor vehicles,a large number of CO and NO from fossil fuel combustion have caused serious air pollution,which caused a serious damage for environmental and human health.Hence the purification of exhaust gas has been paid more and more attention.There are many way to eliminate CO and NO,among which catalytic elimination is a universal and efficient method.Ni is an earth-abundant metal,which has good redox and stability.As a catalyst,it has great potential in practical application.This study focused on metal modified Ni-based oxides to improve their catalytic activity,the main contents of the study are as follows:Ni-Co composite oxides were synthesized by a facile liquid-precipitation method without the addition of surfactant,and their ability to catalyse a low temperature CO oxidation was investigated.In order to explore the effect of the synergetic interaction between Ni and Co on the physicochemical properties and catalytic performance of these catalysts,the as-prepared samples were characterized using XRF,XRD,LRS,N2-physisorption(BET),SEM,TEM,XPS,H2-TPR,O2-TPD characterization techniques.The results show:compared with NiO,the catalytic activity of Ni-Co composite oxide catalyst was significantly improved,among which the Ni0.8Co0.2 sample exhibited the optimal catalytic performance.Doping of Co could reduce the size of NiO and produced a large amount of highly dispersed amorphous NiO on catalyst surface,which makes the catalyst surface is rich in active Ni2+ ions;Ni2+ partially substituted Co3+ to form spinel structure,resulting in a large number of surface oxygen vacancies.Active Ni2+ and oxygen vacancies are key factors in the catalytic oxidation of CO.LaNi0.5M0.5O3(M = Co?Mn?Cu)composite oxides were synthesized by modified sol-gel method,and their ability to catalyse CO reduction NO reaction was investigated.The as prepared samples were characterized by XRD N2-physisorption(BET),SEM,ICP-AES,XPS,Hz-TPR and O2-TPD.The effects of different transition metal doping into LaNi03 perovskite on the structure,chemical composition,redox properties and catalytic activity were studied.The results show that doped with these three-transition metals can improve the activity of the catalyst,and the LaNi0.5Cu0.5O3 catalyst exhibits the optimal catalytic performance,Cu2+ partly substituted Ni3+ in perovskite structure,resulting in a large number of oxygen vacancies.This is the key to the significant improvement of catalyst activity.Finally,the in situ DRIFTS technique used to study the species change of the surface reaction of the catalyst,and the reaction mechanism of CO oxidation and NO reduction by CO on the corresponding catalyst has tentatively proposed.