Svensson Rasmus, Grönbeck Henrik
Department of Physics and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
J Phys Chem Lett. 2024 Aug 8;15(31):7885-7891. doi: 10.1021/acs.jpclett.4c01659. Epub 2024 Jul 26.
Capturing the dynamic character of metal nanoparticles under the reaction conditions is one of the major challenges within heterogeneous catalysis. The role of nanoparticle dynamics is particularly important for metal alloys as the surface composition responds sensitively to the gas environment. Here, a first-principles-based kinetic Monte Carlo method is developed to compare the dynamics of dilute PdAu alloy nanoparticles in inert and CO-rich atmospheres, corresponding to reaction conditions for catalyst deactivation and activation. CO influences the dynamics of the activation by facilitating the formation of vacancies and mobile Au-CO complexes, which are needed to obtain CO-stabilized Pd monomers on the surface. The structure of the catalyst and the location of the Pd monomers determine the rate of deactivation. The rate of catalyst deactivation is slow at low temperatures, which suggests that metastable structures determine the catalyst activity at typical operating conditions. The developed method is general and can be applied to a range of metal catalysts and reactions.
捕捉反应条件下金属纳米颗粒的动态特性是多相催化领域的主要挑战之一。纳米颗粒动力学的作用对于金属合金尤为重要，因为其表面组成对气体环境敏感。在此，开发了一种基于第一性原理的动力学蒙特卡罗方法，以比较稀钯金合金纳米颗粒在惰性和富一氧化碳气氛中的动力学，这两种气氛分别对应催化剂失活和活化的反应条件。一氧化碳通过促进空位和可移动的金 - 一氧化碳络合物的形成来影响活化动力学，而这些对于在表面获得一氧化碳稳定的钯单体是必需的。催化剂的结构和钯单体的位置决定了失活速率。在低温下催化剂失活速率较慢，这表明亚稳结构决定了典型操作条件下的催化剂活性。所开发的方法具有通用性，可应用于一系列金属催化剂和反应。
