Enhanced performances of bimetallic Ga-Pt nanoclusters confined within silicalite-1 zeolite in propane dehydrogenation

Abstract

Ga-based catalysts are promising for use in propane dehydrogenation (PDH) because of the relatively superior activity, but the conventional Ga-based catalysts usually suffer from serious deactivation and unsatisfactory propene selectivity. Here, ultrafine bimetallic Ga-Pt nanocatalysts encapsulated into silicalite-1 (S-1) zeolites (GaPt@S-1) were synthesized by a facile ligand-protected direct H2-reduction method. It is indicated that this catalyst is composed of confined ultra-small GaPt alloy nanoclusters and a part of isolated tetrahedral coordination of Ga species. The confined GaPt alloy nanoclusters are the active sites for PDH reaction, and their high electron density could boost the desorption of products, resulting in a high propene selectivity of 92.1% and propene formation rate of 20.5 mol g−1Pt h−1 at 600 °C. Moreover, no obvious deactivation was observed over GaPt@S-1 catalyst even after 24 h on stream at 600 °C, affording an extremely low deactivation constant of 0.0068 h−1, which is much lower than that of the conventional Ga-based catalysts. Notably, the restriction of the zeolite can enhance the regeneration stability of the catalyst, and the catalytic activity kept unchanged after four consecutive cycles.