Macroporous Ni-based Catalysts For H₂Production From Ethanol Steam Reforming

Ni has been used as one of the most preferred active component for ethanolsteam reforming （ESR） reaction due to its low cost, excellent activity and highhydrogen selectivity. The major concern for the Ni-based catalyst is the deactivationdue to coking, metal sintering and phase transformation. Generally, the activecomponent of a catalyst works more efficiently only in combination with awell-organized structure. Recently, a macroporous monolithic material is proposed tobe beneficial to heterogeneous catalysis, especially from the viewpoint of their lowresistance of heat and mass diffusion, regular macroporous structure and high surfacearea as well as excellent thermal and chemical stability.In this work, a three-diamensional ordered macroporouus （3DOM） Ni/Mg-Alcatalyst is prepared using colloidal PS as the template via a citric acidroute.Characterization results show that the3DOM catalyst has a very high surfacearea and pore volume, and the active component is highly dispersed on spinel supportof MgAl2O4. Compared to the catalyst prepared without template, the3DOM catalystexhibits better reactivity at both700and800oC in terms of higher H2but lower CH4yields. Moreover, the3DOM catalyst maintains its excellent activity and small Niparticles, with a moderate coke accumulation, after100h on-stream at700oC.On the other hand, a macro-meso-porous Al₂O₃monolith has been prepared byfilling PS foam templates with the corresponding hydrosol, and followed byimpregnation of Mg and Ni for a macro-meso-porous monolithic Ni/Mg-Al catalyst.The catalyst has a regular macroporous structure, a surface area larger than230m²/gand a Ni dispersion higer than5.62%. Compared to the conventional meso-poroussample, the macro-meso-porous monolithic Ni/Mg-Al catalyst exhibits a higher H2selectivity and maintains its high activity after100h on-stream at700oC, as well as agood resistance to coking and metal sintering. This may attributed to the macroporousstructure induces the formation of a hierarchical macro-meso-porous structure,improved the surface area and Ni dispersion and enhaced mass and heat diffussion,which all benefit the catalytic stability.Summary: Ni is highly dispersed on the hierarchical macro-meso-porous supportof the macroporous Ni/Mg-Al catalyst, improved the active sites, which enhanced thecatalytic performance and stability in ESR reaction.