C/O杂化调变Ni催化苯分子脱氢及开环反应性能的理论研究

C/O hybrid tuning the catalytic activity of Ni for dehydrogenation and ring-opening of benzene:A theoretical account

基于密度泛函理论计算,对比研究了Ni,Ni/O,Ni/C,Ni/C/O杂化体系的电子特性以及催化苯分子脱氢和开环反应的性能。实验结果表明,单独C或O原子对Ni外层轨道的杂化降低了Ni的化学活性,而C/O同时与Ni外层轨道杂化促进了Ni外层电子的离域,提高了Ni/C/O杂化体系与苯分子的键合作用。不同催化剂催化苯分子脱氢及C—C键断裂开环反应的结果表明,Ni及其杂化体系对苯分子的催化脱氢作用微弱,但显著影响了苯分子C—C键断裂开环反应。动力学和热力学分析结果显示,Ni催化苯分子开环反应的催化活性最高,单独C或O原子对Ni的杂化降低了催化活性,C/O同时杂化进一步降低了催化活性。本工作为新型Ni基催化体系的分子设计及催化反应过程优化提供了基本的理论认识,也可为其他复合催化剂分子设计及性能调控提供借鉴。

The electronic properties and the catalytic effect of Ni,Ni/O,Ni/C and Ni/C/O hybrid system on the dehydrogenation and C—C breakage reaction of benzene were detected using density functional theory calculations.Results showed that hybrid between C or O and Ni atom deactivates the chemical activity of Ni,while both C and O atom hybrid with Ni delocalizes the electrons in the outer orbits of Ni atom,promoting the bonding between benzene and the Ni/C/O hybrid system.Further,the catalytic dehydrogenation and C—C breakage of the ring by different catalysts showed that Ni-based catalyst and its various hybrid systems had little effect on the dehydrogenation of benzene,but great effect on the C—C breakage reaction,where the kinetics and thermodynamics analysis implied that the hybrid by single C or O atom decreases the catalytic activity of Ni,and the hybrid by both C and O atom further deactivates the catalytic activity of Ni.The findings not just provide fundamental understanding of designing novel Ni-based catalyst and optimizing catalytic processes,but offer references for the molecular design and property modulation of other complex catalysts.