Influence of H2 on the gas-phase decomposition of formic acid: a theoretical study.
Gas-phase decomposition of formic acid results in final products CO + H2O and CO2 + H2. Experimentally, the CO/CO2 ratio tends to be large, in contradiction with mechanism studies, which show almost equal activation energies for dehydration and decarboxylation. In this work, the influence of H2 on the decomposition mechanism of HCOOH was explored using ab initio calculations at the CCSD(T)/6-311++G**//MP2/6-311++G** level. It was found that, in the presence of H2, the reaction channels leading to CO + H2O are more than those leading to CO2 + H2. With competitive energy, H2 addition to HCOOH can reduce the latter into HCHO, which then dissociates into CO + H2 catalyzed by H2O. Compared to trans-HCOOH, cis-HCOOH and cis-C(OH)2, conformers required for decarboxylation, are less populated due to interactions with H2.
Hu
Shao-Wen
SW
Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing, China 100871. sw-hu@163.com
Wang
Xiang-Yun
XY
Chu
Tai-Wei
TW
Liu
Xin-Qi
XQ