Preparation and characterization of hydrolysis component γ-Ga₂O₃ for hydrogen production by low temperature steam reforming of dimethyl ether in slurry reactor

The oxide of gallium was prepared by homogeneous precipitation in organic solvent. The physical structure and surface properties were characterized by XRD, NH₃-TPD, TEM and BET. The results reveal that γ-Ga₂O₃ was obtained after 500 ℃ heat treatment of the precursor of GaOOH. The lattice type of the γ-Ga₂O₃ is similar to that of γ-Al₂O₃, which belongs to cubic, cation-deficient spinel structure. The γ-Ga₂O₃ has a moderate acid center with larger amount of acid content. Most of the γ-Ga₂O₃ is two-dimensional nanoflakes with thickness of 10 nm and diameter of 100 nm. These nanoflakes are mainly distributed in one direction, and some of them form petal-shaped patterns. The experimental results showed that the conversion rate of dimethyl ether (DME) was about 24% at 270 ℃, which was close to equilibrium conversion. The texture properties of the catalyst had no significant change after the reaction and the specific surface of the catalyst was about 130 m²/g. The composite catalyst composed of the γ-Ga₂O₃ and Cu-based catalyst was used to DME steam reforming reaction in slurry bed at 270 ℃. The conversion of DME and selectivity of H₂ were as high as about 99% and 68%, respectively. The conversion of DME was over 95% after reaction time of 200 h.