Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, Netherlands.
Haldor Topsoe A/S, Haldor Topsøes Allé 1, DK-2800 Kongens Lyngby, Denmark.
Nat Commun. 2016 Oct 5;7:13057. doi: 10.1038/ncomms13057.
For decades it has been debated whether the conversion of synthesis gas to methanol over copper catalysts is sensitive or insensitive to the structure of the copper surface. Here we have systematically investigated the effect of the copper particle size in the range where changes in surface structure occur, that is, below 10 nm, for catalysts with and without zinc promotor at industrially relevant conditions for methanol synthesis. Regardless of the presence or absence of a zinc promotor in the form of zinc oxide or zinc silicate, the surface-specific activity decreases significantly for copper particles smaller than 8 nm, thus revealing structure sensitivity. In view of recent theoretical studies we propose that the methanol synthesis reaction takes place at copper surface sites with a unique configuration of atoms such as step-edge sites, which smaller particles cannot accommodate.
几十年来，人们一直在争论铜催化剂上合成气转化为甲醇的反应对铜表面结构是否敏感。在这里，我们系统地研究了在工业甲醇合成条件下，铜粒子尺寸在表面结构发生变化的范围内（即低于 10nm）对催化剂的影响，其中包括有和没有锌助剂的催化剂。无论氧化锌或硅酸锌以锌助剂的形式存在与否，铜粒子小于 8nm 时，表面比活性显著降低，从而显示出结构敏感性。鉴于最近的理论研究，我们提出甲醇合成反应发生在铜表面具有独特原子构型的活性位上，如阶梯边缘位，而较小的粒子无法容纳这些原子构型。
