Shifting reaction path for levulinic acid aqueous-phase hydrogenation by Pt-TiO₂ metal-support interaction

Levulinic acid (LA) aqueous-phase hydrogenation into γ-valerolactone (GVL) is considered one of the pivotal reactions to convert biomass into renewable chemicals. Here we have deposited Pt on TiO₂ nanofilm coated α-Al₂O₃ via atomic layer deposition (ALD) to synthesize Pt-TiO₂/α-Al₂O₃. This catalyst shows excellent activity and stability (1000 h) in LA hydrogenation compared to Pt/α-Al₂O₃. By excluding the effect of Pt particle size, lattice plane, support morphology, pore structure, and electronic state, the critical role of Pt-TiO₂ interaction is revealed by various characterization methods. CO diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and in-situ Fourier transform Infrared spectra (FTIR) results indicate that Pt-TiO₂ interaction provides new interfacial Pt sites for LA and intermediate adsorption and Ti-OH active sites for LA dehydration cyclization to α-angelica lactone intermediate, which leads to the shift of reaction pathways from direct LA C[dbnd]O hydrogenation lactonization on Pt/α-Al₂O₃ to LA dehydration cyclization and hydrogenation on Pt-TiO₂/α-Al₂O_3。It provides insight into the design of high-efficient catalysts for aqueous-phase hydrogenation.