Alkane Activation over Acidic Zeolites: The First Step

The heterogeneous acid-catalyzed activation step of alkalies leading to the reaction intermediates (carbo-cationic or alkoxy species) was up to now the matter of a longstanding controversy. Gas chromatography and online mass spectroscopy measurements show that H-2 and methane are formed over H-zeolites, whereas HD and CH3D are formed over D-zeolites as the primary products in the reaction with isobutane. These results indicate that o-bond protolysis by strong acid sites is the first step for hydrocarbon activation on these catalysts at mild temperatures (473 K), in analogy to the activation Path Occurring ill liquid superacid media.