Ethanol Steam Reforming Over A CeO₂-Modified Ni/SBA-15 Catalyst

With rising global demands for energy,diminishing availability of fossil fuels,and growing concerns upon pollution prevention,alternative and environmentally friendly energy sources have captured much attention in recent research.Hydrogen is a clean energy carrier and its application in proton exchange membrane fuel cells(PEMFC)for electricity generation only produces water.H2 used in current industries is mainly obtained from fossil fuels,which leads to co-production of significant amounts of greenhouse gas CO2.Biomass and biomass-derivatives offer renewable hydrogen sources and a theoretically closed carbon loop.Consequently,great efforts have been undertaken to efficiently extract hydrogen from biomass,among which ethanol steam reforming(ESR)is of great interests to chemical industry due to the high H2 yield and mature technology to produce ethanol from biomass.In the past few years,the interests in developing hydrogen fuel cells have spurred extensive studies upon ESR process,many of which focus on investigating various catalytic systems.Non-noble metal-based catalysts,especially Ni-based catalysts,are widely employed in the reforming process due to their low costs,wide availability and excellent capability for C-C and C-H bonds rupture.However,Ni-based catalysts generally suffer rapid deactivation caused by sintering of active nickel species and coke deposition,which remains a major challenge for developing robust Ni-based catalysts.This thesis describes the design and synthesis of CeO2-modifed Ni/SBA-15 catalysts for hydrogen production from ethanol steam reforming.Two major strategies have been applied,namely,incorporation of nickel nanoparticles inside the ordered mesoporous channels of SBA-15 silica and addition of ceria promoter.The spatial confinement effect as well as the strong metal-support interaction induced by ceria addition effectively suppress catalysts from deactivation via metal sintering and carbon deposition.Therefore,the ceria-promoted Ni-based catalysts with encapsulated structure exhibit superior performance in ESR for H2 production.