Ga₂O₃/Al₂O₃ Catalysts for Propane Dehydrogenation: Effect of H₂ Treatment and Cofeeding

Abstract

Abstract This study investigated the catalytic dehydrogenation of propane over uncalcined, calcined, or pre‐reduced gallium‐supported alumina catalysts. The effects induced by a reductive pretreatment and hydrogen cofeeding (5% and 50% in volume in the gas mixture) on the catalytic performance were evaluated. For comparison, a non‐supported γ‐Ga 2 O 3 sample was prepared. The catalysts were characterized by different methods, including XRD, TEM, SEM, NMR, TPR, FTIR, pyridine‐FTIR, and the model reaction of 3,3‐dimethylbut‐1‐ene isomerization. It was found that reductive pretreatment improved the propylene production in gas phase but decreased the initial conversion compared to the calcined sample. Hydrogen cofeeding positively impacted the catalytic stability of reduced catalysts, leading to a higher conversion after 240 min and reducing the deactivation of the catalyst up to 70% as the amount of H 2 increased in the stream. Moreover, improvement in the carbon balance and reduction of carbon deposited were observed at a high H 2 cofeeding ratio. The formation of gallium hydride species during the reduction pretreatment under H 2 flowing was clearly identified, but their contribution in the PDH reaction can be considered as negligible compared to the positive effect induced by the decrease in acidity due to the reducing pretreatment.