A DFT Study On Hydrodeoxygenation Of Phenol On Pt(111) Surface

Biomass energy is the fourth largest energy in the world.Compared with the traditional energy,biomass energy is renewable,carbon neutral and without geographical restriction.Fuel-producing from lignin biomass is an effective way to use biomass energy,while the hydrogenation and hydrogenation deoxidization process of phenol compounds is a critical step in to complete the conversion.In this paper,density functional theory study was used to explore the hydrodeoxygenation paths of phenol on Pt?111?surface.A combined experimental and density functional theory calculation study was performed to understand the reaction mechanism of hydrodeoxygenation of phenol on the Pt?111?surface.Partial hydrogenation of phenyl ring reduces the barrier of deoxygenation.The intermediate formed by adding 5 H atoms to the phenyl ring and with?-C adsorption on Pt is identified as the key intermediate responsible for the formation of different products with mild barriers:deprotonating the hydroxyl to cyclohexanone?0.38 eV?,hydrogenation at?-C to cyclohexanol?0.56 eV?,and deoxygenation?0.76 eV?and followed by dehydrogenation to benzene.Microkinetic parameter analysis indicates that the hydrogenation steps are fast and reversible while deoxygenation steps are slow and almost irreversible,which is consistent with the experimental observation that hydrogenation products are the major primary products at low conversions while deoxygenation product dominates at high conversions,at 523 K and ambient H₂pressure.H₂ pressure plays an essential role on surface coverage of H and available adsorption sites,modulating the competition between hydrogenation and deoxygenation reactions and,thereby,the product distributions.The deoxygenation,hydrogenation and tautomerism reaction are both considered in this paper.To analyze the effect of temperature and hydrogen partial pressure on the product selectivity,we used the microkinetic parameter analysis.Combined with m-cresol hydrodeoxygenation on platinum from the experimental data,we obtained the main reaction paths for phenol hydrodeoxygenation on Pt?111?and this is the theoretical foundation for experimental research.