Support-facet-mediated metal–support interaction regulation of Pt-based catalysts for efficient dehydrogenation

Abstract

A methylcyclohexane (MCH)/toluene (TOL) system is considered a promising candidate for large-scale green hydrogen storage, and catalytic MCH dehydrogenation is the key reaction for effective system recycling. The electronic structure of Pt active sites, as an important property, determines the dehydrogenation dynamics, but the mechanism underlying its effect on dehydrogenation is still ambiguous. Herein, we propose a support (CeO₂) facet-mediated method to rationally regulate metal–support interaction as well as d-orbital electron occupation of Pt sites for efficient MCH dehydrogenation. Characterizations indicate that the interfacial Pt–O coordination numbers are reduced from Pt/CeO₂(110) to Pt/CeO₂(111) and Pt/CeO₂(100), leading to a gradual decrease in interfacial charge transfer and metal–support interaction (MSI). The in situ characterization of catalytic reactions and DFT calculation results confirm that the rate-limiting step of dehydrogenation is the desorption of the products H₂ and TOL. The MCH dehydrogenation performances show catalytic activities in the order of Pt/CeO₂(111) > Pt/CeO₂(110) > Pt/CeO₂(100). Notably, Pt/CeO₂(111) with a moderate MSI induces moderate e_g-orbital electron occupation of Pt–O–Ce sites to accelerate H₂ formation and desorption, while the resulting least t_2g-orbital electron occupation of Pt–Pt sites weakens TOL adsorption, thereby showing the best TOL yield of 91.2% at 350 °C and a WHSV of 4.62 h⁻¹. This work reveals the mechanism of support-facet-mediated d-orbital electron occupation regulation of Pt sites, which provides guidance for the rational design of highly efficient dehydrogenation catalysts.