Exploring the Reaction Mechanism of Methanol Steam Reforming on CuZn₃O₃ Cluster: A Density Functional Theory Study

Hydrogen gas is not only an essential industrial raw material but also an important clean energy. The hydrogen production by methanol steam reforming (MSR) has attracted much attention due to its mild reaction conditions and high hydrogen yield. Herein, the MSR reactions on CuZn₃O₃ cluster are explored using theoretical calculations. It is found that the adjacent Cu and Zn atoms in CuZn₃O₃ cluster play the synergistic roles in the MSR reaction. Specifically, the reaction starts with the adsorption of H₂O and CH₃OH on the Zn atoms. Then, the adsorbed CH₃OH and H₂O dehydrogenate, and the produced oxygen-containing intermediates (CH₃O* and *OH) remain adsorbed on the Zn atoms. The dissociated H atoms migrate to the nearby Cu atoms. In their subsequent dehydrogenation, this rule is still followed. With the participation of H₂O, CH₂O* combines with OH* to form CH₂OOH*, followed by consecutive dehydrogenation to produce CO₂ and H₂. Moreover, the formate (HCOO*) pathway is the least energy-demanding pathway compared with the carboxyl (COOH*) pathway. The synergistic roles of adjacent Cu and Zn atoms in CuZn₃O₃ cluster may provide insight into the structure-activity relationship of CuZnO interfacial sites in related MSR catalysts.