Boron-Induced Redispersion of Pt Species during Propane Dehydrogenation

Abstract

In a propane dehydrogenation (PDH) reaction system, low-Pt catalysts generally suffer from rapid deactivation and poor durability due to easy sintering at high temperatures and in a reductive atmosphere. Herein, we develop a catalyst (PtSnK-B/Al₂O₃, named as PtSnK-B0.32) with both low Pt loading (0.15 wt %) and high durability by facile doping of trace boron into a conventional Pt-based catalyst. Density functional theory (DFT) calculations show that pure Pt clusters have weak binding energy with support, leading to a further undesired Pt sintering process. In contrast, when boron (B) is added to the Pt-based catalyst, the undesired Pt sintering process is significantly inhibited. Moreover, being initiated by propane molecules, the pure Pt clusters are readily to dissociate into Pt atoms due to their longer Pt-Pt bond lengths, then the dissociated Pt atoms are captured by B or BO_x species to form stable Pt–B clusters under PDH conditions. The formation of highly dispersed Pt–B clusters allows the catalyst to achieve high intrinsic activity; compared with the catalyst without B (PtSnK, 0.14 wt % Pt), the E_a value of the B-doped catalyst is obviously reduced. Significantly, the durability of PtSnK-B0.32 is three times that of PtSnK and even twice that of 0.26PtSnK with a Pt loading of 0.26 wt %. The facile synthesis method, lower Pt content, and higher durability provide a promising application perspective.