DFT Study of Direct\nPropylene Epoxidation over the\nDisordered Surface Oxide of Cu<sub>12</sub>O<sub>6</sub>/Cu(111)

Propylene epoxidation reaction is a significant catalytic\nprocess\nutilized in a diverse range of other industrial processes and has\nbeen employed for the synthesis of numerous high-value products. Cu-based\ncatalysts have been extensively researched as cost-effective and environmentally\nfriendly catalysts for the epoxidation of propylene. In this paper,\nCu<sub>12</sub>O<sub>6</sub>/Cu(111) is selected as the precursor\nof bulk oxidation. Generalized ab initio molecular dynamics (AIMD)\nsimulation shows that Cu<sub>12</sub>O<sub>6</sub>/Cu(111) is a highly\nstable surface oxide under the condition of selective oxidation of\npropylene. The key competitive reactions of dehydrogenation and epoxidation\non the surface of Cu<sub>12</sub>O<sub>6</sub>/Cu(111) with lattice\noxygen (O<sub>L</sub>), adsorbed oxygen atoms (O*), and molecular\noxygen (O<sub>2</sub>*) as oxidants have been studied utilizing density\nfunctional theory. Due to the high energy barrier of O<sub>L</sub> as a key step of the oxidizing agent, O* and O<sub>2</sub>* are\nmainly used as oxidizing agents in the whole process of the propylene\noxidation reaction. The results show that the reaction mechanism of\nthe O2 molecule as an oxidizing agent is better in reactivity and\nselectivity than that of the O atom as the oxidizing agent. The Cu<sub>12</sub>O<sub>6</sub>/Cu(111) surface exhibits a high level of PO\nselectivity, surpassing the Cu<sup>+</sup> selectivity observed on\nthe Cu<sub>2</sub>O(111) surface and resembling the Cu<sup>0</sup> selectivity of the pure metal surface of Cu(111). It is hoped that\nthis study can provide theoretical guidance for designing good catalysts\nfor propylene epoxidation by controlling the oxidation state of copper\nin the partial oxidation state like surface copper oxide.