Dft Studies Of The Furfural Hydrogenation Mechanism On Different Metal Catalysts

As the process simplification of using agricultural waste to produce furfural, technology increasingly mature and low cost, the formation furfuryl alcohol、2-methylfuran and furan by furfural catalytic hydrogenation reaction receives great interest. Furfural alcohol and2-methyl furan is obtained through carbonyl hydrogenation of furfural with the catalysts contained Cu. Furan is obtained by furfuryl alcohol decarburization catalysed by noble metal catalysts, such as contained Pd and Pt, and in the gas phase reaction, Pt metal catalyst shows better catalytic activity. The mechanism of furfuryl alcohol hydrogenation on Cu and Pt surface was investigated by Dmo3program based on density functional theory generalized gradient approximati on calculations with the slab model. It is helpful to the design of catalyst.Firstly, the periodic on Cu(111) slab model has been designed. The stability adsorption location, geometries and adsorption energies of species were obtained by the geometry optimization. Mulliken population and density of state analysis results were cited to analyze electronic transfer information between adsorbate and substrate. The transition states were searched by the complete LST/QST method. The activation energy barriers and reaction heat data of elementary reaction steps were obtained. In addition, we also designed Pt(111) slab model and studied the mechanism of furfural decarbonylation reaction.The results show that the furfural molecule adsorbed on the Cu(111) plane via O of the branched chain. The intermediate (C4H3O)CH2O is more possible to form through the hydrogenation of C=O. Furfuryl alcohol molecule adsorbed on the Cu(111) plane via-OH, and the intermediate (C4H3O)CH2and (C4H3O)CH2O can be obtained by the furfuryl alcohol decomposition. We obtain more optimal path through compared the energy barriers. The energy barrier of furfuryl alcohol decomposition to form (C4H3O)CH2can be significantly reduced by the participation of hydrogen radical. The intermediate of (C4H3O)CH2is much easier to obtain the H atom from the furfuryl alcohol, that is the formation routine of the product2-methylfuran. In the mechanism C, the calculated barrier for the rate-determining step (C4H3O)CH2O*�' (C4H3O)CHO*+H*is199.0kJ-mol-1The general reaction is2(C4H3O)CH2OH=(C4H3O)CH3+(C4H3O) CHO+H2O.After adsorption on the Pt(111) surface the d orbit of metal surface has strong interaction with π orbit of furfural ring. The aromaticity of furfural ring was damaged and the C atoms were a characteristic of sp3hybrid. We obtain more optimal path through compared the energy barriers. The furfural is much easier to produce an acyl intermediate through losing the H atom from the branched chain than the directly decarburization. Then the product of furan was formed by decarburization and hydrogenation of intermediate. The calculated barrier for the rate-determining step (C4H3O)CO*+*�'C4H3O*+CO*is127.65kJ-mol-1.