Dehydrogenation of propane over a hydrothermal-synthesized Ga2O3–Al2O3 catalyst in the presence of carbon dioxide

The hydrothermal synthesis method was adopted to prepare a highly active Ga2O3–Al2O3 catalyst (GA-HS), which displayed superior catalytic performance for dehydrogenation of propane to propylene in the presence of CO2 (DHP-CO2). The highest propane conversion on GA-HS was 35.2%, which was much higher than that from the catalysts prepared using the grind-mixture method (8.7%) or coprecipitation method (26.2%). Moreover, propylene selectivity over the GA-HS catalyst was higher than that over the other catalysts in a period of 9 h of reaction. These catalysts were characterized by N2 physical adsorption, ICP-AES, XRD, TGA, TEM, SEM, DRIFT, Py-FTIR, NH3-TPD, XPS, 27Al MAS NMR and 71Ga MAS NMR techniques. The characterization data indicated that the hydrothermal treatment increased the surface area, expanded the pore size and promoted the formation of more tetrahedral Ga ions and the generation of more medium-strong Lewis acid sites. Furthermore, this catalyst mainly displayed an amorphous sponge-like morphology as well as a new morphology whereby some pieces were covered with amorphous nanoparticles. The superior activity of GA-HS was attributed to the higher surface area of this catalyst and the larger amount of tetrahedral Ga ions (Ga3+ and probably Gaδ+δ < 2) related to the medium-strong Lewis acid sites.