The Application Of Catalysts By In-situ Coupled Assembly Of Metal Oxides And Molecular Sieve In Methane Reforming Reaction

Among the potential hydrocarbons utilized for hydrogen generation,methane has the advantage of extensive source,low cost,high hydrogen content and complete storage-transport facilities.It has been widely recognized in the fossil fuels reforming producing hydrogen.With the redox,unsteady state and high temperature,some problems existed in the traditional Ni-based catalyst of methane steam reforming,especially the low catalytic activity and stability.Therefore,the research on excellent support and catalyst has become one of the hot topics in the field of hydrogen production by methane reforming.In this paper,two methods,which include synthesis of new catalyst support and in-situ coupled assembly,were developed to solve the key scientific problems in hydrogen production.Firstly,based on ceria-zirconia solid solution,the homogeneous precipitation hydrothermal method was adopted to prepare the composite molecular sieve catalyst NiO/CZ-SX.The effect of water content in the precursor solution was investigated.The result shoe that compared with NiO/CZ prepared by homogeneous precipitation,NiO/CZ-SX exhibited the most strong interaction between the active components and supports,and it also enhanced the delivery ability of surface and body lattice oxygen.And,these characters could effectively improve the activity and hydrothermal stability at high temperature.In addition,the catalyst NiO/CZ-S15 was prepared under the conditions of TPAOH:TEOS:H2O=25:100:15000 and it exhibited the best catalytic performance.Secondly,based on Silicalite-1 which had high temperature hydrothermal stability,the M-Sil-1 supports were prepared by in-situ coupled assembly of metal oxides and Silicalite-1 molecular sieve.It could greatly improve the interaction between active component and support aiming to enhance catalytic activity and stability.Then,the NiO/M-Sil-1 were synthesized by incipient wetness impregnation method.And the effect of different metal on catalytic performance was investigated in detail.According to BET,TEM and other characterization results,NiO/Zr-Sil-1 had largest special surface area,lowest NiO particle size and best catalytic performance in all the NiO/M-Sil-1.Finally,the NiO/Zr-Sil-1 was premised to investigate the effect of the different preparation conditions(roast temperature and Ni content)and process conditions(reaction temperature,H2O/CH4 ratio and space velocity)on catalytic activity.The optimum preparation conditions for the catalyst were determined as roast tempera ture of 500? and loading amount of active components of 10wt%.Above all,NiO/Zr-Sil-1 still retained higher catalytic activity and stability even if the reaction temperature is 800?,the H2O/CH4 ratio is 2,a space velocity is 12000ml·g-1·h-1.