Department of Interface Science, Fritz-Haber Institute of the Max Planck Society, 14195Berlin, Germany.
Department of Physics, Ruhr University Bochum, 44780Bochum, Germany.
J Am Chem Soc. 2023 Feb 8;145(5):3016-3030. doi: 10.1021/jacs.2c11540. Epub 2023 Jan 30.
The hydrogenation of CO to methanol over Cu/ZnO-based catalysts is highly sensitive to the surface composition and catalyst structure. Thus, its optimization requires a deep understanding of the influence of the pre-catalyst structure on its evolution under realistic reaction conditions, including the formation and stabilization of the most active sites. Here, the role of the pre-catalyst shape (cubic vs spherical) in the activity and selectivity of ZnO-supported Cu nanoparticles was investigated during methanol synthesis. A combination of , , and microscopy, spectroscopy, and diffraction methods revealed drastic changes in the morphology and composition of the shaped pre-catalysts under reaction conditions. In particular, the rounding of the cubes and partial loss of the (100) facets were observed, although such motifs remained in smaller domains. Nonetheless, the initial pre-catalyst structure was found to strongly affect its subsequent transformation in the course of the CO hydrogenation reaction and activity/selectivity trends. In particular, the cubic Cu particles displayed an increased activity for methanol production, although at the cost of a slightly reduced selectivity when compared to similarly sized spherical particles. These findings were rationalized with the help of density functional theory calculations.
在 Cu/ZnO 基催化剂上，CO 加氢合成甲醇对表面组成和催化剂结构高度敏感。因此，要优化其性能，就需要深入了解预催化剂结构对实际反应条件下的演变的影响，包括最活跃的反应位点的形成和稳定。在此，研究了在甲醇合成过程中，预催化剂形状（立方体形与球形）对 ZnO 负载的 Cu 纳米颗粒的活性和选择性的影响。综合运用 、 和 显微镜、光谱学和衍射方法，揭示了在反应条件下，所制备的形状各异的预催化剂在形貌和组成上发生了显著的变化。特别是，观察到立方体形催化剂的圆化和（100）晶面的部分损失，尽管这些晶面仍以较小的域存在。然而，最初的预催化剂结构被发现强烈影响其在 CO 加氢反应过程中的后续转化以及活性/选择性趋势。具体而言，与具有相似尺寸的球形颗粒相比，立方体形 Cu 颗粒虽然在选择性上略有降低，但在甲醇的生成方面显示出更高的活性。这些发现借助密度泛函理论计算得到了合理的解释。
