Framework-confined Sn in Si-beta stabilizing ultra-small Pt nanoclusters as direct propane dehydrogenation catalysts with high selectivity and stability†
Industrial propane dehydrogenation (PDH) catalysts generally suffer from low catalytic stability due to coke deposition and metal sintering. Herein, highly stable Pt/Sn-Si-beta catalysts for PDH were prepared by an improved post-synthesis strategy, which consists of dealumination of H-beta and subsequent metal impregnation. It is indicated that Sn species existing in tetrahedral coordination states were incorporated into the framework of dealuminated beta (Si-beta). Meanwhile, Pt species were highly dispersed in the form of ultra-small nanoclusters on Pt/Sn-Si-beta due to the strong interaction between Pt and Sn(IV) sites confined in the Si-beta framework. The prepared Pt/Sn-Si-beta catalysts show excellent catalytic performance for PDH, in which the propene formation rate was 2.3 mol g−1Pt h−1 with a propene selectivity of >99% at 550 °C and the higher propene formation rate was 3.1 mol g−1Pt h−1 at 600 °C. Moreover, the strong Pt–Sn interactions and the confinement effect of Sn in the Si-beta framework inhibit the coke and sintering of Pt clusters, thereby achieving good stability of dehydrogenation and regeneration with almost unchanged catalytic activity during four cycles at 550 °C.