The microcosmic reaction mechanism of methanol and carbon monoxide was studied by density functional theory (DFT). Then, the geometries of the reactants, transition states and products were optimized by using B3LYP method with 6-311＋＋G(d,p) basis set. Vibration analysis and intrinsic reaction coordinate (IRC) method were employed to confirm the structure of transition state and search the reaction path, respectively. The energies of the species were corrected at the CCSD/6-311＋＋G(d,p) level and the possible reaction mechanism of CH₃OH＋CO was proposed. Three probable reaction channels were found with the products respectively as methyl formate, acetic acid and glycollic aldehyde. Results showed that product as methyl formate (without any catalyst) was the dominant reaction channel with the activation energy of 364.715 kJ•mol^－1, which is relatively lower than that for acetic acid (460.775 kJ•mol^－1) and glycollic aldehyde (611.402 kJ•mol^－1). In addition, the energy calculations show that the formations of methyl formate and glycollic aldehyde are endothermic reaction while product as acetic acid is exothermic one.

Key words: CH₃OH＋CO, methyl formate, reaction mechanism, transition states, DFT