Pd/Cu(111)双金属表面催化糠醛脱碳及加氢的反应机理

采用密度泛函理论(DFT)研究糠醛在最稳定Pd/Cu(111)双金属表面上的吸附构型和糠醛脱碳及加氢的反应机理。结果表明,当糠醛初始吸附于O_3-Pd-top、O_7-Cu-hcp位时,吸附构型最稳定,其吸附能为73.4 kJ/mol。糠醛在Pd/Cu(111)双金属表面上更易发生脱碳反应。对于糠醛脱碳反应,所需活化能较低,各个基元反应均为放热反应,糠醛更易先失去支链上的H形成(C_4H_3O)CO,然后中间体脱碳加氢得到呋喃,其中,C_4H_3O加氢生成呋喃所需活化能(72.6 kJ/mol)最高,是反应的控速步骤。对于加氢反应,糠醛与首个氢原子的反应需要最大的活化能(290.4 kJ/mol),是反应的限速步骤。

Decarbonylation and hydrogenation reaction of furfural on Pd/Cu(111) surface

The adsorption behavior, decarbonylation and hydrogenation reaction mechanisms of furfural on best Pd/Cu(111) bimetallic model were investigated by density functional theory method. The results show that the initial adsorption at O₃-Pd-top and O₇-Cu-hcp site is most stable, with the adsorption energy of 73.4 kJ/mol. On the Pd/Cu(111) bimetallic surface, decarbonylation reaction of furfural is more likely to occur. The decarbonylation reaction of furfural has low activation energy. Each steps of decarbonylation mechanism is exothermic reaction. Furfural tends to form (C₄H₃O)CO by losing the H atom from the branch chain, and furan is then formed by decarbonylation and hydrogenation of the intermediate. Throughout the process, the hydrogenation of C₄H₃O is the rate-determining step with the highest activation energy barrier of 72.6 kJ/mol. For the hydrogenation of furfural, reacting with the first hydrogen is the rate-determining step, and it has the highest reaction energy barrier of 290.4 kJ/mol.