La 3+ cations exchanged into ultrastable zeolite Y and zeolite X promote catalytic isomerization, cracking, and alkylation of alkanes. La 3+ cations stabilize the zeolite lattices and, more importantly, polarize alkane C−H bonds to enhance the rates of all three reactions. This unique activity leads to stable cracking and isomerization of reactive alkanes, with polarizable C−H bonds with adjacent tertiary or quaternary carbon atoms below 370 K. The presence of La 3+ cations also enhances the zeolite catalyzed hydride transfer rate for isobutane alkylation with 2-butene leading to high catalyst stability. Solid state MAS NMR shows that the strongest positive effects are associated with nonhydroxylated La 3+ cations accessible to the reacting molecules in supercages of the zeolite. The high activity is the result of a cooperative polarization of C− H bonds of alkanes by La 3+ cations and the presence of stable and strong Brønsted acid sites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.