Catalytic dehydrogenation of dodecahydron-ethyl carbazole on supported Pt–Cu catalyst: Mechanistic insights into diffusion, bimetallic synergistic and support effects

Performance of the dehydrogenation catalyst is an essential issue for hydrogen storage and transportation based on liquid organic hydrogen carriers (LOHC). To overcome the problem of traditional supported noble metal catalysts, suffering from relatively low catalytic activity and selectivity, this work designed an efficient Pt–Cu synergistic catalyst by introducing additional N, O and other coordination sites as metal anchoring points in the Al 2 O 3 support during catalyst preparation. This strategy achieved high spatial isolation of Cu from Pt nanoparticles (NPs) by adding the regulator of imidazolidinyl urea to the catalytic support, actualizing highly dispersed Pt and Pt–Cu alloy nanoparticles (NPs) and subsequently quantifiable synergistic catalytic effect for dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC). Notably, the catalytic activity of Pt 2·0 Cu 0·1 /Al 2 O 3 -MR catalyst was substantially higher than that of Pt 2·1 /Al 2 O 3 -MR. A peak Pt–Cu synergistic index of 1.39 was attained in the dehydrogenation rate-determining step. The excellent synergistic effect between the Pt and Cu components was attributed to the modified electronic properties of the novel Pt–Cu alloy species under spatial confinement and the suppression of strong metal-support interactions (SMSI), as reflected by several characterization tools like XPS and HRTEM. Furthermore, the catalytic activity is also influenced by diffusion effects. DFT calculation further helped revealing that the Cu component was beneficial for the Pt cluster to lower the reaction barrier of the rate-determining step of 12H-NEC dehydrogenation.