Gas-phase propene oligomerization: A comparative study of micro- and mesoporous acid catalysts

Oligomerization of light olefins is a key step in producing sustainable liquid fuels, yet the interplay between catalyst acidity, pore structure, and operating conditions remains insufficiently understood. Here we compare microporous, mesoporous, and a hierarchical silica–alumina catalysts to elucidate how structural and acidic properties influence activity and product selectivity in gas phase propene oligomerization. All catalysts displayed apparent first-order behavior in propene consumption. Oligomerization rates scaled with acid site density across all materials. A synergistic effect between micro- and mesoporosity was observed, with the hierarchical catalyst displaying the highest oligomerization activity, attributed to improved accessibility of micropore openings through the mesoporous framework. Product selectivity correlated strongly with conversion, reflecting the increasing interconversion of olefins through secondary cracking and oligomerization reactions. Further differences in selectivity were observed between the microporous and mesoporous catalysts, which showed higher cracking and dimer selectivity, respectively. The operating temperature was further found to be of major importance, not only affecting conversion, but also changing the mobility of the occluded hydrocarbons. Increasing temperature promoted secondary cracking reactions while reducing micropore filling, thereby increasing micropore accessibility and alleviating associated mass-transport limitations.