Graphical abstract

The rigorous operating conditions required for propane dehydrogenation result in undesired side reactions on Pt catalysts. Herein, we present the successful suppression of structure-sensitive side reactions by modifying Pt/Al₂O₃ catalysts with P. The characterization of the P-modified Pt/Al₂O₃ catalysts revealed the coexistence of metallic Pt and Pt–P alloys on the surfaces of the Pt nanoparticles. At a reaction temperature of 600 °C, the Pt catalyst modified with an optimal amount of P exhibited a notably higher propylene selectivity (95%) than that of the unmodified Pt/Al₂O₃ catalyst (typically ∼83%), without any loss of activity. A detailed investigation revealed that the geometric effect resulting from the formation of the Pt–P alloy, which reduced the size of the Pt ensembles, was mainly responsible for the enhanced performance of P-modified Pt/Al₂O₃. This study offers vital insights into the formation of noble metal–P alloys on nanoparticle surfaces and their advantageous effects on heterogeneous catalysis.