Composite catalyst of sorption enhanced water gas shift for hydrogen production:A review
Sorption enhanced water gas shift reaction(SEWGS)is one of the critical reactions for high-purity hydrogen preparation and carbon dioxide emission reduction.The composite catalyst is utilized to couple catalytic water gas shift(hydrogen production)with in-situ CO2 removal(decarbonization)during SEWGS,which could break the thermodynamic limitations by moving the chemical equilibrium towards the hydrogen production to achieve enhanced hydrogen production.SEWGS has the characteristic of one-step production of high-purity hydrogen.However,problems with the composite catalyst,such as sintering and hindered CO2 diffusion during continuous SEWGS hydrogen production,lead to a decrease in cycle stability,thereby affecting the hydrogen production efficiency.This work elaborates on the current research status of high-temperature Ni/CaO-based composite catalysts for sorption enhanced hydrogen production.The existing problems of Fe/CaO-based composite catalysts in SEWGS for hydrogen production are briefly described.The current status and core problems of medium temperature Cu/MgO-based and Cu/layer double hydroxides are discussed.From the perspectives of the catalytic components and the sorbent components of composite catalysts,the reasons for the reduced stability are analyzed,and the most effective modification methods currently available are briefly described.Furthermore,modification strategies are proposed from the design of the composite catalyst,operational conditions,and bed loading methods of reactor,to improve the cycle stability of composite catalyst,focusing on enhancing CO2 diffusion and lowering sintering resistance.It highlights that the design and development of composite catalysts that are simple in composition,easy to prepare,as well as high activity and stability,for the coupled production of hydrogen and decarbonization,are the future research direction in SEWGS for hydrogen production.
hydrogen productioncomposite catalystwater gas shift reactionsorption enhancedCO2 diffusionsinteringstability