Structure Evolution Of Cerium-based Catalysts Under Temperature Driven And The Effect On CO+O₂ Reaction Performance

In recent years,as environmental issues have become increasingly prominent,the consensus on the prevention and control of atmospheric pollutants has gained popularity.Among them,the increase of carbon monoxide?CO?content in the atmosphere will cause serious health and environmental problems,thus many countries around the world have adopted many technical methods to try to reduce the concentration of CO in the atmosphere.Scientific facts prove that the catalytic oxidation of CO is one of the most effective technologies for removing such pollutants,and the most critical part is the development and production of efficient,economical,and stable catalysts.In the selection of catalyst materials,many researchers have found that Ce-based catalysts have excellent oxygen storage and release properties and good Ce³⁺/Ce⁴⁺switching capabilities,especially after being modified by transition metal ion doping.In this paper,we focus on the effects of thermal drive on its structure and the reaction performance of CO oxidation,including exploring the process of Ni ion migration in nickel-cerium catalysts and changes in physicochemical properties.Including the feasibility of Cu species dispersion and cross-carrier migration on SBA-15 carrier.The specific research contents are as follows:1.A Ce_xNi_1-xO_2-?catalyst with a nickel-cerium ratio of 1:9 was prepared by the co-precipitation method,and a series of nickel-cerium catalysts were obtained after the catalyst was acid-treated and heat-treated in different temperatures.We used CO oxidation as a model reaction to investigate the differences in the catalytic performance of this series of catalysts.It was found that the oxidation conversion of CO after the acid treatment of nickel-cerium catalysts increased with the increase of the calcination temperature,and was significantly higher than the corresponding acid-treated samples;Through XRD,BET and Raman analysis methods,we found that the catalyst has not changed significantly in terms of structural properties such as grain size and specific surface area;and XPS results show that Ni ions can migrate from the Ce O₂ bulk phase to the surface through heat treatment,and also It can be removed by acid treatment.At the same time,the results of H₂-TPR prove that the redox performance of the nickel-cerium catalyst calcined at different temperatures has changed significantly.The above results comprehensively prove that the migration of Ni ions mainly depends on factors such as the temperature of heat treatment,and that the enhancement of the catalytic performance of the catalyst is closely related to the increase of the interaction between the surface of Ni and Ce caused by the increase of the surface Ni species.2.Cu/SBA-15 and Ce/SBA-15 catalysts with 5 wt%Cu O and 20 wt%Ce O₂ were prepared by mechanical grinding and roasting.Firstly,the effect of Ce O₂ addition on the structure of Ce/SBA-15 catalyst and the performance of CO oxidation reaction was investigated.It was found that when calcined at 450?,Cu O originally dispersed on Si O₂ would flow and migrate due to lattice vibration,and then dispersed to the surface of Ce O₂,a Cu-Ce interface is formed and the reactivity is enhanced.With the increase of the calcination temperature,the dispersion of Cu is gradually strengthened.Furthermore,we mixed Cu/SBA-15 and Ce/SBA-15 catalysts and other masses,and prepared Cu-Ce/SBA-15 catalysts calcined at different temperatures by solid-phase impregnation method.By observing and analyzing the CO oxidation reaction performance of different catalysts,we found that copper species on the surface of Si O₂can migrate and disperse across the support under temperature driving,and form a strong interaction with Ce on the surface of another support,and improve the calcination.Temperature will also enhance this interaction.