Study On The Application Of Ni-based Reverse Water Gas Shift Reaction Catalysts

Transportation is an indispensable and important part of our life.With the popularization of various transportation methods,people pay more and more attention to the pollution they produce.The use of a large number of fossil energy fuels in the field of transportation will emit a large amount of greenhouse gas CO₂.At the same time,CO₂ is also the most abundant and cheap carbon source in the world,so the conversion and utilization of CO₂ has attracted worldwide attention.Among them,the reverse water gas shift（RWGS）reaction is one of the most promising reactions.Ni-based catalysts have the unique advantage of low prices and are widely used in RWGS research.However,Ni-based catalysts have the disadvantages of poor high-temperature thermal stability and low selectivity.In this thesis,Ni-based catalysts were prepared by different methods,and excellent catalysts for reverse water gas shift reaction were developed.The main research contents are as follows:1、A series of Ni/SiO₂-x N catalysts with different ratios of urea were prepared by urea-assisted impregnation,and the effects of urea on the activity and high temperature stability of the catalysts were investigated.Through the performance test,it was found that the catalytic activity and stability of the catalyst in RWGS reaction gradually improved with the increase of urea content.Through H₂-TPR,TEM and other characterization tests,the introduction of urea can effectively enhance the metal-support interaction and contribute to the formation of highly dispersed small Ni nanoparticles,thus improving the activity and high temperature stability of Ni catalyst.2、La₂O₃ was prepared by solution combustion method,and Ni-x K/La₂O₃ catalysts with different K content were prepared by K promoter assisted impregnation method.The effect of K promoter on the performance and selectivity of the catalyst was investigated.The performance test of RWGS showed that the selectivity of by-product CH₄ decreased gradually with the increase of the percentage of K additive.Adding a small amount of K promoter can improve the activity and high temperature stability of the catalyst.3、Bimetallic NiCu/SiO₂-N catalysts were prepared by urea-assisted impregnation method for RWGS reaction.Ni/SiO₂ has high catalytic activity and CH₄ selectivity;Cu catalyst has low catalytic activity but has 100%selectivity to CO.The formation of NiCu alloy in bimetallic catalyst can inhibit the production of CH₄and significantly improve the selectivity of CO.The NiCu/SiO₂-N catalyst prepared by urea-assisted impregnation method has better catalytic activity and thermal stability,while maintaining good CO selectivity.