Study On The Adsorption Of Guaiacol On The Surface Of Transition Metals Based On DFT

The energy crisis and environmental problems have become more serious which non-renewable fossil resources on the verge of depletion has been exploited and used continuously.Low-carbon,green,and environmentally friendly renewable energy has been developed and used which has become the current research trend.Lignin is the second largest polymer in nature,and it is the only renewable resource with a low price,a wide range of sources,and an aromatic ring structure.Catalyzing and turning the lignin can get phenols,aromatic chemicals and high-grade hydrocarbon fuels that can be replaced some processes that use fossil resources as raw materials to produce chemicals and fuels.In the process of catalytic conversion of lignin,transitional metal catalysts are widely used.The catalytic conversion of lignin with Cu and Rh that belong to different main groups as catalysts can be studied to understand the function of transitional metal system to lignin better.Adsorption is a necessary step in the catalytic reaction and the catalyst can only occur catalytic reaction when the reactants have chemical adsorption with the catalyst.Therefore,the study on the metal surface adsorption of catalytic conversion process about lignin and its model can provide a theoretical basis for the selection and preparation of high-efficiency catalysts.This paper use the adsorption behavior of guaiacol of lignin model compound and VASP software to study the surface of Cu（111）,Rh（111）and Ce-Cu（111）modified by Ce through the structural optimization,differential charge density,Bader charge and density of state.Guaiacol was stable in the Hcp30°-Top-Fcc when it adsorbed on the surface of Cu（111）and its adsorption energy was 128.94 kJ/mol.The hybridization of the P orbit of guaiacol and the D orbit on the Cu（111）surface is the main reasons for the adsorption and catalytic reaction between guaiacol and metal Cu.The P orbit is provided by the C atom on the aromatic ring and the O atom（O1）on the methoxy.The geometric deformation of Ce-Cu（111）surface based on interposition is most stable after Ce atom modified Cu（111）surface.The most stable adsorption site was Bridge_Ce-Cu30o-Bridge_Ce-Cu-Bridge_Cu-Cuu-Cu when guaiacol was adsorbed on Ce-Cu（111）surface.The adsorption energy was 221.27 kJ/mol and the C-O bond between the C-OH of before and after adsorption with the aromatic ring changes mostly.Guaiacol and the p-orbital of Ce-Cu（111）surface have an electronic cross bred effect in the region of-18.0to-17 eV through the density of states.The p orbitals are provided by Ce atoms.The yiosquinol O1p,O2p,and Cp orbitals have hybridized with the d orbitals of the Ce-Cu（111）surface at-5.0eV to Fermi level,and the d orbitals are provided by Cu atoms.To sum up,when guaiacol adsorbs on the surface of the three metals,the order of adsorption energy is:Rh（111）>Ce-Cu（111）>Cu（111）;By contrast,the surface of Cu（111）interacts strongly with methoxy.The surface of Cu（111）after Ce modification has strong interaction with hydroxyl group.And the interaction between Rh（111）surface and aromatic ring is stronger than other two groups.