The mechanism of carbon dioxide hydrogenation to methanol over Cu/ZnO materials has been explored for decades; however, the question of the active site still remains open to discussion. We used operando time-resolved X-ray absorption spectroscopy (XAS) and time-resolved isotope labeling experiments coupled with Fourier transform infrared (FTIR) spectroscopy and mass spectrometry (MS) analysis to elucidate the reaction mechanism and study the active sites and intermediates over a Cu/ZnO catalyst during carbon dioxide conversion into methanol. No reduction of the zinc oxide or formation of a copper–zinc alloy was observed even under highly reducing conditions (15 bar of hydrogen, 260 °C), which leads to the conclusion that a copper–zinc alloy phase is not required for high methanol yields and selectivity to be obtained. We attribute the reactive superiority of the copper–zinc-based system to the interplay between copper and zinc oxide phases. Our synthesis protocol provides a way to produce this copper–zinc oxide interface, without having to go through an alloy phase.

中文翻译：

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Cu / ZnO /八面沸石上二氧化碳催化无铜锌合金合成甲醇

数十年来，人们一直在探索在Cu / ZnO材料上二氧化碳加氢成甲醇的机理。但是，活动站点的问题仍然有待讨论。我们使用了操作时间分辨X射线吸收光谱（XAS）和时间分辨同位素标记实验，以及傅立叶变换红外（FTIR）光谱和质谱（MS）分析来阐明反应机理并研究活性位点和中间产物二氧化碳转化为甲醇期间的Cu / ZnO催化剂。即使在高度还原的条件下（15 bar的氢气，260°C）也没有观察到氧化锌的还原或铜锌合金的形成，这得出结论，高甲醇不需要铜锌合金相得到的产率和选择性。我们将铜锌基体系的反应性优越归因于铜和氧化锌相之间的相互作用。我们的合成规程提供了一种生产铜-氧化锌界面的方法，而无需经过合金相。