Ni_(1)/g-C_(3)N_(4)催化乙炔加氢反应的密度泛函理论研究

Density functional theory study on Ni_(1)/g-C_(3)N_(4) catalytic hydrogenation of acetylene

乙烯是石化产业的主要原料之一,广泛运用于工业生产和基本生活。乙烯中少量的乙炔杂质从根本上会影响下游产品,那么乙炔选择性加氢就可以提高乙烯产量,减少杂质产生。本文中构建了Ni_(1)/g-C_(3)N_(4)催化剂模型,以密度泛函理论为依据,从B3LYP泛函基组出发,计算过程中采用DFT-D3校正。对Ni原子使用LAN2DZ赝势,对于C,H,N非金属原子使用6-31g**基组。通过分析静电势、态密度和在催化剂上的吸附行为,系统性研究了Ni_(1)/g-C_(3)N_(4)催化剂催化乙炔加氢的反应机理,详细阐述了选择性和活性。结果表明,Ni_(1)/g-C_(3)N_(4)催化乙炔加氢的最优反应路径是乙炔加氢生成乙烯,能垒是20.05 kcal·mol^(-1);乙烯加氢生成乙烷,能垒是90.29 kcal·mol^(-1)。Ni_(1)/g-C_(3)N_(4)催化剂具有低活性、高选择性的特征,展现了其良好的催化性能,为乙炔高效催化加氢领域提供了帮助。

Ethylene is one of the main raw materials in the petrochemical industry and is widely used in industrial production and basic life.A small amount of acetylene impurities in ethylene will fundamentally affect downstream products,so selective hydrogenation of acetylene can increase ethylene production and reduce impurities.In this paper,the Ni_(1)/g-C_(3)N_(4)catalyst model is constructed,based on density functional theory,starting from the B3LYP functional basis set,and using DFT-D3 correction in the calculation process.The LAN2DZ pseudopotential was used for Ni atoms and the 6-31g**basis set for C,H,N non-metallic atoms.By analyzing the electrostatic potential,density of states and adsorption behavior on the catalyst,the reaction mechanism of Ni_(1)/g-C_(3)N_(4)catalyst for acetylene hydrogenation was systematically studied,and the selectivity and activity were also elaborated.The results show that the optimal reaction path for Ni_(1)/g-C_(3)N_(4)catalyzed acetylene hydrogenation is hydrogenation of acetylene to ethylene with an energy barrier of 20.05 kcal·mol^(-1);hydrogenation of ethylene to ethane with an energy barrier of 90.29 kcal·mol^(-1).The Ni_(1)/g-C_(3)N_(4)catalyst has the characteristics of low activity and high selectivity,showing its good catalytic performance,which provides help for the field of efficient catalytic hydrogenation of acetylene.