Catalytic performance of gallium oxide based-catalysts for the propane dehydrogenation reaction: effects of support and loading amount

Abstract

The different materials (ZSM-5, SBA-15, γ-Al₂O₃ and SiO₂) were used as supports for Ga₂O₃-based catalysts for the propane dehydrogenation reaction, and the effect of Ga₂O₃ content (1–9 wt%) for xGa₂O₃/SBA-15 catalysts on the catalytic activity was discussed. It is found that the supports determine the porous features, the state and dispersion of Ga species, and the acid–base properties of the corresponding catalysts. The existence of strong acid sites in catalyst can lead to more well-dispersed Ga species. The satisfied catalytic performances are obtained over 5Ga₂O₃/ZSM-5 and 5Ga₂O₃/SBA-15 catalysts. Among the Ga₂O₃-based catalysts with different supports, the 5Ga₂O₃/ZSM-5 sample exhibits the highest catalytic activity, which possesses the maximum well-dispersed gallium species and high dehydrogenation efficiency gallium ions (Ga^δ+ cations, δ < 2), and the 5Ga₂O₃/SBA-15 catalyst exhibits the highest catalytic stability. Furthermore, as for the xGa₂O₃/SBA-15 samples, the 5Ga₂O₃/SBA-15 sample exhibits the best catalytic performance. The initial propane conversion and propylene selectivity are above 32.0% and 90.0% respectively, and a final propane conversion of 17.0% is obtained after 30 h reaction. With the increase of Ga loading, the Ga species are easily agglomerated and destroy the structural integrity of the SBA-15 support, which is unfavorable to the propane dehydrogenation reaction.