A Study Of Catalyst Research Based On Efficient And Stable Conversion Of Natural Gas

As non-renewable energy sources such as coal and oil are increasingly depleted,natural gas,as a clean energy source,has received widespread attention,especially in the context of the sustainable development goals of"carbon peak"and"carbon neutrality".The methane dry reforming reaction（DRM）can directly convert the two major greenhouse gases,methane and carbon dioxide,into synthesis gas,which has both environmental and economic benefits and has therefore attracted much attention.Considering the economic benefits of precious metals,non-precious metal catalysts have shown good application potential,but compared with precious metal catalysts,they are more prone to sintering and carbon deposition,which limits their industrial application.This paper prepared two carbon-modified oxide-supported Ni-based catalysts for methane dry reforming reaction by using high-temperature carbonization-assisted wet impregnation method and high-temperature carbonization-assisted hydrothermal synthesis method,respectively,aiming to improve the coking resistance performance and catalytic stability of Ni-based catalysts.Firstly,a series of nitrogen-doped carbon surface-modified zirconia-supported Ni catalysts（Ni/Zr O₂@NC-xh）were prepared by high-temperature carbonization-assisted wet impregnation method,and the amount of nitrogen-doped carbon was adjusted by changing the dopamine polymerization time.The Ni/Zr O₂@NC-3h catalyst had the best DRM reaction performance and coking resistance performance.Density functional theory studies showed that the introduction of carbon can effectively reduce the formation energy of oxygen vacancies in the Zr O₂ support.The rich oxygen vacancies in Ni/Zr O₂@NC-3h catalyst were confirmed by XPS,EPR,XANES and other characterization methods.Stability tests showed that the production of oxygen vacancies effectively improved the anti-coking performance of the catalyst.After stability tests for 80 h,the methane（CH₄）conversion rate and carbon dioxide（CO₂）conversion rate of Ni/Zr O₂@NC-3h catalyst remained at 61.4%and 73.6%,respectively,without any deactivation signs.Secondly,in order to further explore the effect of the type of introduced carbon on the reaction activity,carbon-modified hydrotalcite-supported Ni catalyst（Ni/LDH-C1）and nitrogen-doped carbon-modified hydrotalcite-supported Ni catalyst（Ni/LDH@NC-3h）were prepared by high-temperature carbonization-assisted hydrothermal synthesis method.Stability tests showed that the introduction of carbon effectively increased the stability and coking resistance performance of the hydrotalcite-supported Ni catalyst.However,the CH₄conversion rate of Ni/LDH@NC-3h catalyst was 38.0%,and the CO₂ conversion rate was73.5%,which was higher than the CH₄ conversion rate（29.7%）and CO₂ conversion rate（58.1%）of Ni/LDH-C1 catalyst.XPS,UPS and other characterization methods showed that nitrogen-doped carbon had certain electronic interactions with the metal Ni,which changed the electronic structure of the metal Ni and thus affected the catalytic activity and stability.