Chemistry Division, Brookhaven National Laboratory, Upton, NY 11973, USA.
Chemistry Department, Stony Brook University, Stony Brook, NY 11794, USA.
Science. 2020 May 1;368(6490):513-517. doi: 10.1126/science.aba5005.
Highly selective oxidation of methane to methanol has long been challenging in catalysis. Here, we reveal key steps for the pro-motion of this reaction by water when tuning the selectivity of a well-defined CeO/CuO/Cu(111) catalyst from carbon monoxide and carbon dioxide to methanol under a reaction environment with methane, oxygen, and water. Ambient-pressure x-ray photoelectron spectroscopy showed that water added to methane and oxygen led to surface methoxy groups and accelerated methanol production. These results were consistent with density functional theory calculations and kinetic Monte Carlo simulations, which showed that water preferentially dissociates over the active cerium ions at the CeO-CuO/Cu(111) interface. The adsorbed hydroxyl species blocked O-O bond cleavage that would dehydrogenate methoxy groups to carbon monoxide and carbon dioxide, and it directly converted this species to methanol, while oxygen reoxidized the reduced surface. Water adsorption also displaced the produced methanol into the gas phase.
甲烷的高选择性氧化在催化领域一直具有挑战性。在这里，我们揭示了在甲烷、氧气和水的反应环境中，通过调节定义明确的 CeO/CuO/Cu(111)催化剂的选择性，从一氧化碳和二氧化碳到甲醇的关键步骤，当水促进该反应时。常压 X 射线光电子能谱表明，添加到甲烷和氧气中的水会导致表面甲氧基，并加速甲醇的生成。这些结果与密度泛函理论计算和动力学蒙特卡罗模拟一致，表明水优先在 CeO-CuO/Cu(111)界面上的活性铈离子上离解。吸附的羟基物质阻止了 O-O 键的断裂，从而将甲氧基脱氢生成一氧化碳和二氧化碳，并且它直接将该物质转化为甲醇，同时氧气将还原的表面重新氧化。水的吸附也将产生的甲醇排入气相中。
