Hydrogen Production via Glycerol Steam Reforming over Ni/Al2O3: Influence of Nickel Precursors

This paper describes an investigation regarding the influence of Ni precursors on catalytic performances of Ni/Al 2 O 3 catalysts in glycerol steam reforming. A series of Ni/Al 2 O 3 is synthesized using four different precursors, nickel nitrate, nickel chloride, nickel acetate, and nickel acetylacetonate. Characterization results based on N 2 adsorption–desorption, X-ray diffraction, H 2 temperature-programmed reduction, H 2 chemisorption, transmission electron microscopy, and thermogravimetric analysis show that reduction degrees of nickel, nickel dispersion, and particle sizes of Ni/Al 2 O 3 catalysts are closely dependent on the anion size and nature of the nickel precursors. Ni/Al 2 O 3 prepared by nickel acetate possesses the moderate Ni reduction degree, high Ni dispersion, and small nickel particle size, which possesses the highest H 2 yield. Reaction parameters are also examined, and 550 °C and a steam-to-carbon ratio of 3 are optimized. Moreover, coke deposition, mainly graphite species, leads to the deactivation of Ni/Al 2 O 3 catalysts in glycerol steam reforming. Nickel chloride-derived Ni/Al 2 O 3 catalysts suffer from severe coke deposition and low reaction activity due to large Ni particle size, low Ni dispersion, and residual chloride.