Pt-Carbon interaction-determined reaction pathway and selectivity for hydrogenation of 5-hydroxymethylfurfural over carbon supported Pt catalysts

In this study, a series of Pt catalysts supported on carbon materials, including multi-walled carbon nanotubes (CNTs), reduced graphene oxide (rGO), graphitic carbon nitride (g-C₃N₄), and biochar (BC), were prepared by impregnation or atomic layer deposition (ALD) methods. The Pt content was around 2.5 wt% in all the Pt catalysts, and the average Pt particle size was 1.6-1.9 nm for the catalysts prepared by impregnation (IM), which was slightly larger than that for the Pt catalyst (∼1.4 nm) synthesized by ALD (Pt/CNTs-ALD). All the catalysts were used in the HMF hydrogenation reaction to investigate the effects of different carbon materials and Pt-carbon interactions on the catalytic performance of catalysts. The main product was DHMF over all the Pt catalysts prepared by impregnation, and Pt/BC-IM showed the highest turnover frequency and the highest selectivity to DHMF (95.3%) with an HMF conversion of 94.6% after 10 h of reaction time, which could be due to the abundant functional groups on the surface of BC. Compared with the Pt/CNTs-IM catalyst, the main product over the Pt/CNTs-ALD catalyst was DMF with a yield of 47% due to the relatively strong Pt-CNT interaction. The interaction between Pt and CNTs is the dominant factor in determining the main product in the selective HMF hydrogenation reaction. After introducing Ni nanoparticles to Pt/CNTs-ALD, the yield of DMF reached 93.4% over the PtNi/CNTs-ALD bimetallic catalyst owing to the synergistic effect between Pt and Ni.