Mechanochemical synthesis of ZnO.Al2O3 powders with various Zn/Al molar ratios and their applications in reverse water-gas shift reaction.

ZnO.Al2O3 powders with various Zn/Al molar ratios were prepared via a solid-state reaction using a mechanochemical synthesis method, and the selected powder with a ZnO/Al2O3 molar ratio of 1 was used as support for the preparation of 15% Ni/ZnO.Al2O3 catalyst. The activity of the prepared catalyst was studied in the reverse water-gas shift (RWGS) reaction. The synthesized samples were characterized by XRD, BET, TGA/DTA, TPR, FTIR, and SEM techniques. The results indicated that the prepared powders possessed mesoporous structure with pores having small diameters with crystallite sizes in the nanometer range (6.35-12.08 nm). The results showed that the increment in Zn/Al molar ratio reduced the BET area and the pure Al2O3 powder possessed the highest BET area (235.4 m2 g-1). The results also indicated that the rise of calcination temperature remarkably decreased the BET area. The prepared nickel-based catalyst also exhibited a high activity in RWGS reaction.