Deciphering active site dynamics through interfacial engineering of Pt–Mo catalysts for the efficient dehydrogenation of liquid organic hydrogen carriers

Abstract

In this study, we developed high-performance Pt–Mo catalysts for the dehydrogenation of monobenzyltoluene, a homo-cyclic liquid organic hydrogen carrier (LOHC), focusing on the promotional role of molybdenum (Mo). Incorporating Mo into Pt/Al2O3 significantly enhanced catalytic activity, with the optimized 2Pt0.4Mo/Al catalyst achieving a 74 % dehydrogenation degree—approximately 10 % higher than the Pt-only counterpart. Spectroscopic (XPS, XAFS) and surface (CO-DRIFTS, H2-TPD) analyses revealed that Mo preferentially interacts with undercoordinated Pt sites, inducing electron withdrawal and promoting hydrogen spillover via adjacent MoOx domains. These effects improve the regeneration of active sites by modulating the adsorption–desorption dynamics of hydrogen and LOHC molecules. DFT calculations confirmed that MoOx clusters anchor onto low-coordinated Pt sites, driving charge redistribution and enhancing turnover frequency. However, excessive Mo loading leads to coverage of Pt active sites, resulting in a loss of catalytic efficiency. These findings underscore the importance of optimizing Mo content and highlight metal–oxide interfacial engineering as a key strategy in designing advanced LOHC dehydrogenation catalysts.