Huang Xing, Teschner Detre, Dimitrakopoulou Maria, Fedorov Alexey, Frank Benjamin, Kraehnert Ralph, Rosowski Frank, Kaiser Harry, Schunk Stephan, Kuretschka Christiane, Schlögl Robert, Willinger Marc-Georg, Trunschke Annette
Department Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany.
Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195, Berlin, Germany.
Angew Chem Int Ed Engl. 2019 Jun 24;58(26):8709-8713. doi: 10.1002/anie.201902750. Epub 2019 May 30.
The direct conversion of syngas to ethanol, typically using promoted Rh catalysts, is a cornerstone reaction in CO utilization and hydrogen storage technologies. A rational catalyst development requires a detailed structural understanding of the activated catalyst and the role of promoters in driving chemoselectivity. Herein, we report a comprehensive atomic-scale study of metal-promoter interactions in silica-supported Rh, Rh-Mn, and Rh-Mn-Fe catalysts by aberration-corrected (AC) TEM. While the catalytic reaction leads to the formation of a Rh carbide phase in the Rh-Mn/SiO catalyst, the addition of Fe results in the formation of bimetallic Rh-Fe alloys, which further improves the selectivity and prevents the carbide formation. In all promoted catalysts, Mn is present as an oxide decorating the metal particles. Based on the atomic insight obtained, structural and electronic modifications induced by promoters are revealed and a basis for refined theoretical models is provided.
合成气直接转化为乙醇，通常使用促进型Rh催化剂，这是CO利用和储氢技术中的一个基础反应。合理的催化剂开发需要对活化催化剂的详细结构以及促进剂在驱动化学选择性方面的作用有深入了解。在此，我们通过像差校正（AC）透射电子显微镜对二氧化硅负载的Rh、Rh-Mn和Rh-Mn-Fe催化剂中金属-促进剂相互作用进行了全面的原子尺度研究。虽然催化反应导致在Rh-Mn/SiO催化剂中形成Rh碳化物相，但添加Fe会导致形成双金属Rh-Fe合金，这进一步提高了选择性并防止了碳化物的形成。在所有促进型催化剂中，Mn以氧化物形式存在于金属颗粒表面。基于所获得的原子层面的认识，揭示了促进剂引起的结构和电子修饰，并为完善理论模型提供了依据。
