Ru掺杂对Fe催化剂上酚类化合物加氢脱氧影响的密度泛函理论研究北大核心CSCD

采用密度泛函理论(DFT)计算研究了苯酚、邻甲酚、愈创木酚在不同结构Ru-Fe(211)表面上吸附活化性能和加氢脱氧反应路径.结果表明,Ru掺杂能促进H2分子在Fe(211)表面上解离,提高加氢脱氧反应速率.酚类在1Ru_(ads)-Fe(211)表面上吸附比在1Ru_(sub)-Fe(211)表面上更稳定,苯酚和邻甲酚脱羟基步骤能垒分别降低0.13和0.28 eV,有利于生成芳烃.愈创木酚在1Ru_(sub)-Fe(211)表面上加氢脱氧优势路径是先脱甲氧基生成苯酚,苯酚再加氢脱氧生成产物苯(速控步骤能垒1.16 eV);而在1Ru_(ads)-Fe(211)表面上愈创木酚先脱羟基再脱甲基生成苯酚的路径更具有动力学优势(速控步骤能垒1.21 eV).计算结果表明Ru掺杂方式影响Fe催化剂对酚反应分子的吸附稳定性以及加氢脱氧反应路径和性能.与1Ru掺杂Fe(211)催化剂相比,增加Ru原子数形成4Ru_(ads)-Fe(211),能够进一步提高酚类反应物的吸附强度,但导致加氢脱氧反应能垒升高.因此,在Fe催化剂上以表面吸附的形式掺杂少量贵金属Ru更利于酚类加氢脱氧生成芳烃.

Density Functional Theory Study of The Effect of Ru Doping on The Hydrodeoxygenation of Phenolic Compounds over Fe Catalyst

The adsorption properties and hydrodeoxygenation reaction paths of phenol, o-cresol and guaiacol on Ru-Fe (211) surfaces with different structures were studied by density functional theory (DFT) calculations. The results show that Ru doping can promote the dissociation of H2 molecules on Fe (211) surface and improve the hydrodeoxygenation rates. The adsorption of phenols on 1Ruads-Fe (211) surface is more stable than that on 1Rusub-Fe (211); and the barriers of phenol and o-cresol dehydroxylation are reduced by 0.13 and 0.28 eV, respectively, which is conducive to the formation of aromatic products. The dominant route of guaiacol hydrodeoxygenation on the 1Rusub-Fe (211) surface is demethoxylation and hydrogenation to produce phenol, followed by phenol hydrodeoxygenation to produce benzene (rate-limiting barrier of 1.16eV). On the surface of 1Ruads-Fe (211), the pathway of guaiacol dehydroxylation to anisole followed by demethylation to phenol has more kinetic advantage (rate-limiting barrier of 1.21eV). The calculation results reveal that Ru doping affects the adsorption ability of Fe catalyst for phenolic reactants, as well as the hydrodeoxygenation pathway and performance. Compared to the 1Rusub-Fe (211) catalyst, increasing the number of Ru atoms to form 4Ruads-Fe(211) surface can enhance the adsorption of phenolic reactants, but lead to the increase of hydrodeoxygenation barriers. Therefore, doping a small amount of precious metal Ru on the Fe catalyst in the manner of surface adsorption is more conducive to the hydrodeoxygenation of phenolic compounds to desired aromatic products.