摘要
CO_(2)加氢制甲酸由于需同时活化惰性氢气及CO_(2)而富有挑战性,同时此过程原子经济性100%,具有很好的理论和现实研究价值,但文献中报道的活性较好的催化剂均为贵金属催化剂.为了开发活性更高的用于CO_(2)加氢制甲酸的铁基催化剂,我们采用理论计算方法研究了12种不同种类的PNP-Fe(PNP=2,6-(二-叔丁基-磷甲基)吡啶)化合物催化CO_(2)加氢制甲酸的过程.理论研究结果表明,CO_(2)加氢制甲酸反应过程包括H2活化及CO_(2)插入金属氢键两个步骤,H_(2)活化过程是整个反应的速控步骤.催化剂吡啶环上进行P原子取代可以显著降低H_(2)活化能垒.基于以上发现,我们设计了一种新颖的高效铁基催化剂,使用此催化剂催化CO_(2)加氢制甲酸反应,速控步骤能垒只有85.6 kJ/mol,催化活性与贵金属的比较接近.我们研究的12种铁基催化剂速控步骤能垒范围为85.6~126.4 kJ/mol,显示了配体良好的调控催化活性能力.
CO_(2)hydrogenation is full of challenge because both H_(2)and CO_(2)are activated at the same time.This reaction also has 100%atomic economy.Most of the reported catalysts for CO_(2)hydrogenation are based on noble metal.To find out more effective iron based catalysts for the CO_(2)hydrogenation to formic acid,totally,the reaction processes catalyzed by 12 different PNP-Fe(PNP=2,6-bis(di-tert-butylphosphinomethyl)pyridine)compounds were investigated.The theoretic calculation results revealed that the CO_(2)hydrogenation included two steps:H_(2)activation and CO_(2)inserting into the metal-hydride bond.The H_(2)activation is the rate-determining step.It was found that P atom substitution on the pyridine ring could obviously reduce the H_(2)activation barrier.Based on these findings,an effective Fe catalyst was designed,whose H_(2)activation barrier was only 85.6 kJ/mol,being comparable to the data of precious metal catalyst.The H_(2)activation barriers range from 85.6 to 126.4 kJ/mol for different Fe-based catalysts investigated here,indicating that the modification of ligand has great influence on the catalytic reactivity for the CO_(2)hydrogenation.
作者
刘聪
胡兴邦
LIU Cong;HU Xing-bang(Shandong GuoBang Pharmaceutical Co.,Ltd.,Weifang 261108,China;School of Chemistry and Chemical Engineering,Nanjing University,Nanjing 210023,China)
出处
《分子催化》
CAS
CSCD
北大核心
2022年第2期162-170,共9页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金面上项目(22178159和21878141)
关键词
CO_(2)
加氢
甲酸
理论计算
铁基催化剂
CO_(2)
hydrogenation
formic acid
theoretical calculation
iron catalyst
