Density functional theory calculations on acetaldehyde and glycolaldehyde decompositions over stepped Ni surface

Abstract

Bio-oil catalytic steam reforming for green hydrogen production is a prospective technology. In order to make a clear understanding of the reaction mechanisms on metal surfaces, acetaldehyde and glycolaldehyde were selected as bio-oil model compounds to study their decomposition behaviors on stepped Ni surface via density functional theory calculations. Thirty-three possible elementary reactions of acetaldehyde and glycolaldehye decompositions were proposed. Adsorption energies and geometries of reaction intermediates were presents. Detailed activation energies and reaction energies of elementary reactions were reported, and the favored decomposition pathways were identified. Acetaldehyde undergoes the decomposition through path of CH3CHO → CH2CHO → CH2 + CHO → CH2 + CO. The most preferable decomposition pathway for glycolaldehyde is HOCH2CHO → CH2CHO → CH2 + CHO → CH2 + CO. The rate-determining steps in both two pathways are CC bond cleavage of CH2CHO, which has activation energy of 92.3 kJ/mol.