Mechanistic insights into the dehydrogenation of formaldehyde, formic acid and methanol using the Pt cluster as a promising catalyst.

Reaction mechanisms of the dehydrogenation of formaldehyde, formic acid and methanol on the Pt cluster were computationally investigated using density functional theory (DFT) with the B3LYP functional in the conjunction with the aug-cc-pVTZ basis sets for H, C and O atoms, and the cc-pVDZ-PP basis set for Pt. Herein, the key mechanistic aspects of three possible pathways of the dehydrogenation of these compounds are summarized. The results indicate that the formation of H and CO or CO molecules is more energetically favorable than the generation of H and HO, HCHO products. Generally, the formation of H molecule in the presence of catalysts is more favorable than the direct decomposition of either HCHO, HCOOH or CHOH molecule. The use of Pt catalyst significantly reduces the energy barriers for C-H and O-H bond cleavage of all three compounds to 14, 9 and 12 kcal/mol, respectively. The decomposition of HCOOH is found to be the most energetically favorable. In addition, the mechanistic insights of the reactions confirm the reduction of the energy barriers of the gas-phase dehydrogenation by 67-82 kcal/mol and bring it to the values smaller than 14 kcal/mol in the presence of the Pt catalysts.