Preparation And Performance Study Of CO/CO₂ Co-methanation Catalyst For Biomass Gas Upgrading

To relieve the contradiction between supply and demand of natural gas urbanization and to solve the environmental problems caused by pollutant emission from biomass combustion,preparing urban gas by methanation using biomass gas is of much significance.Nickel-based catalyst is regarded as a promising catalyst in this process because of its excellent performance during CO and CO₂ methanation process,which could realize the promotion of biomass gas and the capture of CO₂ simultaneously.This paper investigated the effect of operating condition,component contents and preparation methods on the performance of catalysts using simulated biomass gas,kinetic analysis was also applied in it.A series of nickel-based catalysts supported on ZrO₂-Al₂O₃ composite support were prepared by impregnation and powder pressing,and were further characterized by N₂isothermal physisorption,X-ray powder diffraction?XRD?,H₂ temperature-programmed reduction?H₂-TPR?,thermogravimetric analysis?TG?,X-ray photoelectron spectroscopy?XPS?,scanning electron microscope?SEM?and transmission electron microscope?TEM?techniques.The influence of nickel component,zirconia addition and different preparation methods was investigated in CO methanation,CO₂ methanation and CO/CO₂ co-methanation,respectively.The results indicated that compared to single component Al₂O₃ support,the addition of zirconia could improve the dispersion of Ni species leading to enhanced catalytic performance in CO methanation.Besides,composite support prepared through powder pressing method could effectively improve the reducibility and decreased the reduction temperature of catalysts in contrast to the impregnation method.However,the former method would decrease the specific surface area,pore volume and pore diameter of the catalysts.In the CO₂ methanation,catalysts prepared both by impregnation method had little effect on CO₂ conversion,which was mainly limited by physical properties such as specific surface area that originated from the difference in preparation method.In the CO/CO₂ co-methanation experiments,CO methanation is prior to CO₂ methanation.In the kinetic analysis,the kinetic equation in the form of power function is established to calculate the activation energy,leading factor and other indexes of the catalyst.Aspen plus is also used to design and optimize the reactor.