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Breaking the Structure–Activity Relationship in Toluene Hydrogenation Catalysis by Designing Heteroatom Ensembles Based on a Single-Atom Alloying Approach
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-07-17 , DOI: 10.1021/acscatal.3c02132 Akira Oda 1, 2 , Takahisa Fujita 1 , Yuta Yamamoto 3 , Kyoichi Sawabe 1 , Atsushi Satsuma 1, 2
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-07-17 , DOI: 10.1021/acscatal.3c02132 Akira Oda 1, 2 , Takahisa Fujita 1 , Yuta Yamamoto 3 , Kyoichi Sawabe 1 , Atsushi Satsuma 1, 2
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Hydrogenation of toluene (TOL) to methylcyclohexane (MCH) is one of the hydrogen carrier systems desired for social integration. Supported Pt nanoparticle catalysts are effective for this application. However, Pt is rare, expensive, and in short supply, limiting its practical applications. Therefore, the key issue for TOL hydrogenation is how to substantially reduce the amount of Pt required for the catalyst. Because a specific ensemble of Pt atoms, that is dominantly formed on the surface of the Pt nanoparticle, is required for achieving higher catalytic performance, there is a limit to the number of precious Pt that can be conserved by simply reducing the particle size. The structure sensitivity established in the existing heterogeneous catalyst so far makes it difficult to design precious metal-conserving catalysts with both high activity and atomic efficiency. Here, a strategy for breaking the above limitations is reported. Our approach uses the heteroatom ensemble (HAE) on Pt single-atom alloyed 3d transition-metal nanoparticle catalysts (Pt1M SAAs, M = Co, Ni, Cu). The role of the TOL fixation/activation site is assigned to the atomic M sites on HAE, whereas the H2-activation site is to the Pt single-atom site on HAE. The atomic-scale division of roles within the HAE improves the efficiency of competitive adsorption of TOL/H2, which is important for boosting TOL hydrogenation. To maximize the synergistic effect at the adjacent sites, the atomic composition, geometric configuration, and electronic state of these active sites as well as the density of the HAE were tuned by the chemical composition and particle size of Pt1M SAAs. High activity was observed on the Pt1Co SAA with a particle size of 1.8 nm and Pt/Co molar ratio of 0.002. The Pt mass-specific activity reached 219 mol/gPt/h, which was 23 times higher than that in a conventional Pt nanoparticle-supported catalyst. Using a set of well-defined Pt1M SAAs, high-angle annular dark-field scanning transmission electron microscopy, Pt LIII-edge X-ray absorption fine structure spectroscopy, coupled with periodic density functional theory and ab initio molecular dynamics simulation, we proved the origin of the structure sensitivity at an atom-to-nanometer scale. The present work sheds light on the significance of regulations of the coordination environment of the Pt single-atom site, atomic composition, and particle size of Pt1M SAA for creating high activity, durability, and Pt-utilization efficiency for catalytic applications relevant to hydrogen carrier systems.
中文翻译：
基于单原子合金化方法设计杂原子系综打破甲苯加氢催化中的构效关系
甲苯（TOL）加氢生成甲基环己烷（MCH）是社会融合所需的氢载体系统之一。负载型 Pt 纳米粒子催化剂对于该应用是有效的。然而，Pt 稀有、昂贵且供应短缺，限制了其实际应用。因此，TOL加氢的关键问题是如何大幅减少催化剂所需的Pt用量。由于要实现更高的催化性能，需要主要在 Pt 纳米颗粒表面形成的特定 Pt 原子集合，因此通过简单地减小颗粒尺寸可以保存的珍贵 Pt 的数量是有限的。迄今为止，现有多相催化剂所建立的结构敏感性使得设计兼具高活性和原子效率的贵金属保守催化剂变得困难。在此，报告了打破上述限制的策略。我们的方法在 Pt 单原子合金化 3d 过渡金属纳米粒子催化剂（Pt1M SAAs，M = Co、Ni、Cu）上使用杂原子系综 (HAE)。TOL 固定/激活位点的作用被分配给 HAE 上的原子 M 位点，而 H2-激活位点是HAE上的Pt单原子位点。HAE内原子尺度的角色划分提高了TOL/H 2竞争吸附的效率，这对于促进TOL氢化非常重要。为了最大限度地发挥相邻位点的协同效应，这些活性位点的原子组成、几何构型和电子状态以及 HAE 的密度通过 Pt1M SAA 的化学成分和粒径进行调整。在粒径为 1.8 nm、Pt/Co 摩尔比为 0.002 的 Pt1Co SAA 上观察到高活性。Pt质量比活度达到219 mol/g Pt/h，比传统 Pt 纳米粒子负载催化剂高 23 倍。利用一套明确的Pt1M SAAs、高角度环形暗场扫描透射电子显微镜、Pt L III边X射线吸收精细结构光谱，结合周期密度泛函理论和从头算分子动力学模拟，我们证明了原子到纳米尺度的结构敏感性的起源。目前的工作阐明了 Pt 单原子位点的配位环境、原子组成和 Pt1M SAA 粒径的调控对于为氢载体相关催化应用创造高活性、耐久性和 Pt 利用效率的重要性系统。
更新日期：2023-07-17
中文翻译：
基于单原子合金化方法设计杂原子系综打破甲苯加氢催化中的构效关系
甲苯（TOL）加氢生成甲基环己烷（MCH）是社会融合所需的氢载体系统之一。负载型 Pt 纳米粒子催化剂对于该应用是有效的。然而，Pt 稀有、昂贵且供应短缺，限制了其实际应用。因此，TOL加氢的关键问题是如何大幅减少催化剂所需的Pt用量。由于要实现更高的催化性能，需要主要在 Pt 纳米颗粒表面形成的特定 Pt 原子集合，因此通过简单地减小颗粒尺寸可以保存的珍贵 Pt 的数量是有限的。迄今为止，现有多相催化剂所建立的结构敏感性使得设计兼具高活性和原子效率的贵金属保守催化剂变得困难。在此，报告了打破上述限制的策略。我们的方法在 Pt 单原子合金化 3d 过渡金属纳米粒子催化剂（Pt1M SAAs，M = Co、Ni、Cu）上使用杂原子系综 (HAE)。TOL 固定/激活位点的作用被分配给 HAE 上的原子 M 位点，而 H2-激活位点是HAE上的Pt单原子位点。HAE内原子尺度的角色划分提高了TOL/H 2竞争吸附的效率，这对于促进TOL氢化非常重要。为了最大限度地发挥相邻位点的协同效应，这些活性位点的原子组成、几何构型和电子状态以及 HAE 的密度通过 Pt1M SAA 的化学成分和粒径进行调整。在粒径为 1.8 nm、Pt/Co 摩尔比为 0.002 的 Pt1Co SAA 上观察到高活性。Pt质量比活度达到219 mol/g Pt/h，比传统 Pt 纳米粒子负载催化剂高 23 倍。利用一套明确的Pt1M SAAs、高角度环形暗场扫描透射电子显微镜、Pt L III边X射线吸收精细结构光谱，结合周期密度泛函理论和从头算分子动力学模拟，我们证明了原子到纳米尺度的结构敏感性的起源。目前的工作阐明了 Pt 单原子位点的配位环境、原子组成和 Pt1M SAA 粒径的调控对于为氢载体相关催化应用创造高活性、耐久性和 Pt 利用效率的重要性系统。
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