Dynamic evolution of CO2 hydrogenation to methanol over Cu catalysts based on ReaxFF MD simulations

MR Dong and ZH Huang and JC Xiong and HC Liu and YC Liang and JD Lu, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 136, 102-114 (2025).

DOI: 10.1016/j.ijhydene.2025.05.049

It is essential to identify key intermediates for elucidating the reaction mechanism by studying the dynamic evolution of the reaction process. In the synthesis of methanol by CO2 hydrogenation, the formation of byproducts CO and H2O affects the selective generation of methanol. In this work, reactive force field molecular dynamics (ReaxFF MD) simulations were proposed to simulate the CO2 hydrogenation reaction on Cu surface. The CO2/H2, CO2/CO/H2 and CO2/H2O/H2 systems were analyzed sequentially in order to explore the dynamic properties of the key intermediate product generation and to elucidate the detailed reaction pathways and their kinetic effects. The results showed that in the CO2/H2 system, there are three different pathways for the methanol production, while two main pathways were found for CO hydrogenation. The synergistic effect between CO2 and CO hydrogenation was demonstrated in the CO2/CO co-hydrogenation to methanol, and the introduction of CO further improved the methanol selectivity. However, in the CO/H2 system, excessive CO adsorption leads to severe C deposition, catalyst deactivation, and reduced methanol yield. Conversely, the incorporation of H2O into the CO2/H2 system was shown to inhibit the C deposition on the Cu catalyst, maintain the catalytic activity, and enhance the methanol selectivity by introducing the methoxy hydrolysis pathway (CH3O + H2O-* CH3OH + HO). It is worth noting that the simulations revealed previously unrecognized CH pathways (CO2-* CH-* CH-* CHO-* CH2O-* CH3O-* CH3OH) and methoxy hydrolysis pathways. The proposed route to synthesize methanol over Cu catalysts not only provides novel insights into methanol synthesis, but also provides the necessary theoretical support for understanding the reaction mechanism of CO2 hydrogenation to methanol.

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