Theoretical insight into hydrogen production from methanol steam reforming on Pt(111)

Abstract

Pt-based catalysts are widely used for hydrogen production from methanol steam reforming (MSR), but they show high CO selectivity. The reaction pathways of MSR on Pt(111) surface are systemically studied using density functional theory and kinetic Monte Carlo to reduce the selectivity of CO. The results show that CH3OH (g) → CH3OH* → CH2OH *→ CHOH * → CHO * → CO * → CO (g) is the main reaction pathway at 423–623 K and 0.1–10 atm with CH3OH: H2O of 3:1–1:1, and water is very difficult to dissociate. The difference between H2O* + * → OH* + H* and CH3OH* +*→ CH2OH * + H* is the key factor for MSR reaction on Pt(111) surface. The actual ratio of H2/(CO+CO2) is close to the theoretical ratio for MSR (2.91 vs. 3.00) when the energy barrier of H2O* + * → OH* + H* is smaller than that of CH3OH* +*→ CH2OH * + H* by 0.30 eV. The elimination of CO* is mainly from CO * + OH * → COOH*, and the ratio of CO/(CO+CO2) is 6.71%. These results may be useful for the design and optimization of Pt-based catalysts at low temperature for MSR reaction.