Effect of preparation method of mesoporous Ni-Al_2O_3 catalysts on their catalytic activity for hydrogen production by steam reforming of liquefied natural gas (LNG)

摘要

Mesoporous Ni-Al_2O_3 catalysts were prepared by impregnation method (NiAl-IP), co-precipitation method (NiAl-CP), and sequential precipitation method (NiAl-SP) for use in hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of preparation method of mesoporous Ni-Al_2O_3 catalysts on their catalytic activity for steam reforming of LNG was investigated. Physicochemical properties of Ni-Al_2O_3 catalysts were strongly influenced by the preparation method of Ni-Al_2O_3 catalysts. Surface area, pore volume, and average pore size of Ni-Al_2O_3 catalysts decreased in the order of NiAl-SP > NiAl-CP > NiAl-IP. Nickel species strongly interacted with Al_2O_3 supports through the formation of nickel aluminate phase. Surface nickel aluminate phase of Ni-Al_2O_3 catalysts was readily reduced after the reduction process, while bulk nickel aluminate phase of NiAl-CP catalyst was hardly reducible. Nickel dispersion and nickel surface area of Ni-Al_2O_3 catalysts decreased in the order of NiAl-SP > NiAl-CP > NiAl-IP. Among the catalysts tested, NiAl-SP catalyst with the highest nickel surface area showed the best catalytic performance in the steam reforming of LNG. Furthermore, finely dispersed nickel species in the NiAl-SP catalyst efficiently suppressed the carbon deposition during the reaction.