Density Functional Theory Study on Interaction of CO2 with Metal Surface Carbon Species in Synthesis of Acetic Acid from CH4/CO2 on Co-Pd Catalysts

作者：Zhang Ri Guang; Huang Wei^*; Wang Bao Jun

来源：Chemical Journal of Chinese Universities, 2009, 30(11): 2252-2257.

• Carbon dioxide
• Acetic acid
• Reaction mechanism
• Cobalt
• Palladium
• Density functional theory
• General gradient approtimationry (GGA)

The insertion reactions of CO2 with M-H (M = Co, Pd) and Pd-CH3 were systematically investigated by the first-principle DFT-GGA calculations. The mechanisms of CO2 reacting with M-H and Pd-CH3 were obtained for the direct synthesis of acetic acid from CH4/CO2 by a two-step reaction sequence on Co-Pd catalysts. The calculation result showed that. the pathway that CO2 inserts into Co-H bonds forming HCOO-Co was the most advantageous in dynamics for all four designed reaction paths. However, HCOO was linked with Co in bi-dentate form, whose binding energy was very large, so the desorption of HCOO hardly taken place and formic acid was little produced. Meanwhile, the pathway that CO2 inserts into Pd-CH3 bonds forming H3CCOO-Pd was secondly preferential pathway favored in dynamics. The binding energy between H-3 CCOO and Pd was small, and desorption of H-3 CCOO easily occur-red, so the main product was acetic acid. While methyl formate was inhibited by dynamics. The calculated result was in accordance with the experimental facts.

• 出版日期2009-11-10
• 单位太原理工大学