Hydrogen donation of bio-acids over transition metal facets: A Density Functional Theory study

Abstract

Bio-acids produced from biomass fast pyrolysis are regarded as alternative hydrogen source for upgrading bio-oil into transport fuels. In this work, the hydrogen donation performance of acetic acid (AcOH) and formic acid (FA) were evaluated over the transition metal facet in comparison with H2 gas, using Density Functional Theory (DFT) modelling. It was revealed that Mo (110) led to stronger binding with the bio-acid molecule than other base transition metals, and the consequent electrons migration significantly facilitated the bio-acids decomposition. AcOH exhibited a greater potential than FA as a hydrogen donor over Mo (110) because it released more H atoms with low energy barriers. H2 gas showed undoubtable merits of dissociative adsorption with negligible energy barrier over Mo (110). However, the larger enthalpy changes from the exothermic decomposition of bio-acids would probably more facilitate the activation and migration of the individual H atoms for their donation compared to H2 gas.