Yang Juanjuan, Cui Yanran, Zhao Ying, Purdy Stephen C, Zhang Junyan, Liu Haoyu, Zheng Yanping, Nie Lei, Li Zhenglong
State Key Laboratory of Biobased Transportation Fuel Technology, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
Division of Biobased Chemicals, Institute of Zhejiang University-Quzhou, Quzhou 324000, China.
J Am Chem Soc. 2025 Jun 25;147(25):22084-22091. doi: 10.1021/jacs.5c06007. Epub 2025 Jun 12.
Capitalizing on the success of single-atom catalysts (SACs), dual-atom catalysts (DACs) have emerged as a new frontier in heterogeneous catalysis. However, most SACs and DACs studies seek to uniformly distribute the catalytic sites on the support material, which can hinder their effectiveness in intricate multistep cascading reactions. Particularly, it is a grand challenge to precisely control the spatial distribution of two different single sites forming binary sites so that reactants and intermediates contact the catalytic sites in the exact sequence required by the reaction steps. Here, we report a new type of binary single-site catalyst, Cu-Zr@SiO, with Cu and Zr sites spatially aligned with the reaction sequence of the cascade reactions. The catalyst is synthesized by a modified reverse microemulsion approach, with single Cu sites anchored by nonbridging oxygen hole centers, which were induced by doping single Zr sites into SiO. Low-energy ion scattering spectroscopy (LEIS) reveals that the outermost surface of the catalyst contains only Cu single sites, while the Zr sites are dispersed in the bulk. The catalytic performance is demonstrated in ethanol conversion to butenes, a model cascade reaction which includes ethanol dehydrogenation and aldol condensation steps. The precisely spatially controlled binary sites enable ethanol to first undergo dehydrogenation to acetaldehyde on Cu sites, followed by aldol condensation of acetaldehyde on Zr sites. As a result, C olefins selectivity as high as 77.0% (56.0% selectivity of butenes) is achieved by suppressing ethylene formation.
基于单原子催化剂（SACs）的成功，双原子催化剂（DACs）已成为多相催化领域的一个新前沿。然而，大多数SACs和DACs研究试图将催化位点均匀分布在载体材料上，这可能会阻碍它们在复杂多步级联反应中的有效性。特别是，精确控制形成二元位点的两种不同单一位点的空间分布，使反应物和中间体按照反应步骤所需的确切顺序与催化位点接触，是一项巨大的挑战。在此，我们报道了一种新型的二元单位点催化剂Cu-Zr@SiO，其Cu和Zr位点在空间上与级联反应的反应顺序对齐。该催化剂通过改进的反相微乳液法合成，单个Cu位点由非桥连氧空穴中心锚定，这些中心是通过将单个Zr位点掺杂到SiO中诱导产生的。低能离子散射光谱（LEIS）表明，催化剂的最外表面仅含有Cu单位点，而Zr位点分散在主体中。在乙醇转化为丁烯的反应中展示了其催化性能，这是一个包括乙醇脱氢和羟醛缩合步骤的模型级联反应。精确的空间控制二元位点使乙醇首先在Cu位点上脱氢生成乙醛，随后乙醛在Zr位点上进行羟醛缩合。结果，通过抑制乙烯的形成，实现了高达77.0%的C烯烃选择性（丁烯选择性为56.0%）。
