Study On Carbon Dioxide Reforming Of Methane By Microwave Catalysis And Its Microwave Catalytic Effects

Methane carbon dioxide reforming to syngas(CO and H2)is one of the important ways to reduce the emissions of greenhouse gas(CH4 and CO2)and realize resource utilization of CH4 and CO2.It is significant to achieve carbon neutrality,mitigate energy crisis and protect the environment.Therefore,it has attracted great research interest of academia and industry in recent years.However,achieving efficient carbon dioxide reforming of methane remains challenge because of the high energy consumption and deactivation of the catalyst caused by carbon deposition.The introduction of microwave field and the development of microwave catalysts with excellent performance can reduce the energy consumption,reduce carbon deposition and improve the conversion rate of CO2 and CH4,which can provide a new way for methane carbon dioxide reforming.The key to achieve low energy consumption and reduce carbon deposition in the reforming reaction is to develop microwave catalysts with excellent performance.Furthermore,the mechanism of microwave catalytic carbon dioxide reforming of methane remains to be elucidated.In order to solve the above problems,a series of new cheap Nickel-based microwave catalysts for the microwave catalytic reforming of methane carbon dioxide were developed.The catalysts were characterized by XRD,TPR,XPS,Raman,TG,BET,TEM,etc.The catalytic performance of microwave catalyst was systematically investigated,and the microwave catalytic effect and reaction mechanism were also discussed.The main research content includes the following sections:(1)The LaNiO3-based perovskite microwave catalysts were prepared.The effect of elemental doping on the performance of the catalyst was studied.The performance difference between microwave and conventional reaction modes was compared.It was found that the catalyst activity was improved after modification of Mg and Sr at A-site.The modification of Cu and Fe at B-site can maintain longer stability.In addition,the activity and stability of La0.8Sr0.2Ni0.8Cu0.2O3 catalyst under microwave reaction mode(MCRM)are higher than those under conventional reaction mode(CRM).(2)Ni-Co/CaZrO3+SiC microwave catalysts were prepared and the effects of active metal types and reaction modes on the performance of the catalysts were investigated.The results show that the performance of Ni-Co/Cazr O3+SiC bi-metal catalysts is better than that of Ni or Co mono-metal catalysts under microwave reaction mode.Moreover,the activity and stability of Ni-Co/CaZrO3+SiC catalyst under microwave reaction mode are higher than the corresponding activity and stability under conventional heating mode.(3)The Ni@SiO2 based microwave catalysts with core-shell structure were prepared,and the effect of hydrolysis time on the structure and properties of the catalyst was investigated.The results showed that complete core-shell structure was formed a after 2 hours hydrolysis,and catalysts with complete core-shell can maintain longtime stability.Moreover,the activity of the core-shell catalyst with Ni content of9.0 wt% is even better than that of the common catalysts with higher Ni loading of15.1wt% and 20.9 wt%.(4)Microwave catalytic effect and reaction mechanism were discussed.It was found that on Ni-Co/ CaZrO3+SiC catalysts the apparent activation energy of methane and carbon dioxide under microwave irradiation decreased from 71.0 k J/mol and 62.5k J/mol to 38.5 k J/mol and 36.25 k J/mol,respectively.By studying the carbon deposition on the surface of the used catalyst under microwave and conventional reaction modes,it was found that microwave irradiation could accelerate the removal of carbon from the surface of the catalyst,and the possible reaction mechanism was speculated.