Effect of calcination temperature of Ni/γ-Al2O3 catalyst on the steam reforming of acetic acid

Ni/γ-Al₂O₃-550 and Ni/γ-Al₂O₃-800 catalysts (calcined at 550°C and 800°C in the catalyst preparation) were prepared with a impregnation method. Steam reforming of acetic acid as a model compound of bio-oil for hydrogen production had been investigated on the catalysts. The fresh catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR-H₂) and specific surface area analysis (BET). The spent catalysts were characterized by temperature programmed oxidation (TPO), differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS). The results showed that the Ni/γ-Al₂O₃-800 catalyst exhibited higher catalytic activity and lower coke formation than Ni/γ-Al₂O₃-550. This was due to the formation of nickel aluminate at higher calcination temperature in the catalyst preparation. Two types of carbon species: Ni_xC and graphitic carbon, were deposited on the Ni/γ-Al₂O₃-550 catalyst and only one type of carbon species: graphitic carbon, was deposited on the Ni/γ-Al₂O₃-800 catalyst. Higher calcination temperature in the catalyst preparation promoted the conversion of Ni_xC.