A DFT study of the effect of K and SiO2 on syngas conversion to methane and methanol over an Mo6P3 cluster

ISSN： 0892-7022

Source： Molecular Simulation, Vol.36, Iss.2, 2010-02, pp. : 118-126

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Abstract

Synthesis gas (CO+H2) conversion to CH4 and CH3OH over an Mo6P3 cluster, an Mo6P3-Si3O9 and a K-Mo6P3-Si3O9 cluster has been studied using density functional theory (DFT). The study focused on the reaction between the intermediate species CH2OHad+Had, comparing methanol formation to C-O bond scission that yields CH2.ad+H2Oad species. The activation energies of both the reactions decreased on the Mo6P3-Si3O9 and the K-Mo6P3-Si3O9 clusters compared to the Mo6P3 cluster. However, on the K-Mo6P3-Si3O9 cluster, the activation energy for methanol formation (12.1 kcal/mol) was higher than the C-O bond-breaking activation energy (9.9 kcal/mol). Although the DFT study predicted preferential formation of CH4 versus CH3OH on all the Mo6P3 clusters, the study also predicted an increased formation of CH3OH with the addition of K and experimental measurements are in agreement with this prediction.