Acid-catalyzed alkene oligomerization is often masked by artifacts of transport limitations. Implications of these limitations on turnover rates and selectivity were assessed on zeolites with diverse frameworks (MFI, MTW, TON) and crystal sizes over a wide range of temperatures (423-573 K). Measured kinetic data, together with Weisz-Prater estimates, show that reactant diffusion limitations can prevail at high oligomerization temperatures (573 K). These data also suggest, through transition state theory formalisms, that structural effects on oligomerization rates arise solely from entropy changes. Isomer speciation of oligomers reveals that the degree of hydrocarbon branching increases with the pore diameter and decreases with diffusional constraints. The ob-served selectivity trends were consistent with sorption transients of structurally relevant hydrocarbons.
Bibliographical noteKAUST Repository Item: Exported on 2023-07-31
Acknowledgements: The authors acknowledge Natalia Morlanes, Adrian Ramirez, Jose Cerrillo, Youssef Saih, Selvedin Telalovic, Daria Poloneeva, Gerard Clancy, Jose Primera, Omar El Tall, and Abdelhamid Emwas for assistance with catalytic testing and structural and chemical characterization. The authors also thank Sandra Ramirez for designing the graphical abstract of this work.