Accurate rate constants for elementary reactions of molecular hydrogen and carbon monoxide mixtures and the role of the H2 rich environment.

Abstract

This investigation provides accurate rate constant values for a set of elementary reactions relevant to mixtures between molecular hydrogen (H2) and carbon monoxide (CO) such as syngas. We considered intermediates and products including formaldehyde (H2CO), hydroxymethylene (c-HCOH and t-HCOH) and methanol (CH3OH). The calculations were performed employing the improved canonical variational transition state theory with small-curvature tunneling corrections based on high-level electronic structure results. This study demonstrates for the first time that H2 can act as an effective catalyst to the reaction from t-HCOH to H2CO. In this case, the adiabatic barrier height for the reaction decreases from 30.6 kcal⋅mol- 1 to 18.1 kcal⋅mol- 1 in the presence of H2. The results obtained here can improve the comprehension regarding processes such as the combustion of hydrogen-rich syngas.