Effects of Partial Confinement on the Specificity of Monomolecular Alkane Reactions for Acid Sites in Side Pockets of Mordenite

Catalytic specificity of side pockets: Monomolecular reactions with higher activation energies—dehydrogenation of linear alkanes (n-butane: blue) and cracking of branched alkanes (isobutane: green)—show a stronger preference for acid sites located within eight-membered ring (8-MR) side pockets in mordenite, where reactants and transition states can only be partially confined. Partial confinement leads to higher entropies and lower free energies for ion pairs at late monomolecular transition states.