Catalysis at the atomic-scale: observing single-site promoted polymerization of small hydrocarbons

原子尺度的催化：观察单中心促进小分子碳氢化合物的聚合

• 批准号: 432043087
• 负责人: Professor Dr. Laerte Patera, Ph.D.
• 金额: --
• 依托单位: Institut für Physikalische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/432043087?language=en
• 关键词: Catalysis; atomic; scale; observing; single

Over the past few years, single-atom catalysts (SACs) have attracted special attention in the field of heterogeneous catalysis, due to their unique chemical activity and selectivity. However, despite single site catalysts are already used in chemical processes, the lack of a fundamental understanding of atomistic mechanisms driving the surface reactions has so far limited the process optimization to empirical data, affecting the catalyst development. In this context, the surface-science approach has proved to have the potential to steer the engineering of catalytic materials, by providing actual atomistic understanding of chemical reactions occurring at interfaces. Nevertheless, these studies are generally restricted to ultra-high vacuum (UHV) conditions, while industrial chemical processes occur at elevated pressures and on complex materials.Here, we aim to obtain mechanistic insights at the atomic scale into single-site promoted reactions. By combining in-situ surface-science methods optimized to work at elevated pressures, namely high-pressure scanning tunneling microscopy (HP-STM) and near-ambient pressure X-ray Photoelectron Spectroscopy (NAP-XPS), we will study the mechanisms governing single-sites catalyzed polymerization of small hydrocarbons under realistic reaction conditions, from model systems towards industrial supported catalysts.First, we will elucidate the hydrocarbon polymerization on a Ni(111) model catalyst, where individual Ni adatoms have been suggested to act as SACs. In-situ STM imaging performed on the millisecond timescale will allow clarifying their role in facilitating the monomer attachment. Following the surface evolution at pressures in the mbar range, by means of HP-STM and NAP-XPS, we aim to unveil how the hydrocarbon polymerization processes observed under UHV evolves going towards conditions commonly used in industrial reactors.Then, we plan to expand the in-situ studies towards “real-world” supported catalysts for olefin polymerization, namely metallocene complexes anchored to an ultrathin alumina support. For this purpose, we will make use of well-defined systems, prepared under controlled conditions to prepare activated single-sites catalysts. This strategy will enable the characterization by means of advanced in-situ microscopy and spectroscopy techniques, shedding light onto the reaction mechanisms and unveiling the nature of the catalytic active species under realistic reaction conditions.In this way, we aim to clarify long-standing questions about the role of single-site catalysts during industrial chemical processes, with potential implications in the design of new catalysts.

在过去的几年中，单原子催化剂（SAC）由于其独特的化学活性和选择性而在多相催化领域引起了特别关注。然而，尽管单中心催化剂已经在化学过程中得到应用，但缺乏合适的催化剂。迄今为止，对驱动表面反应的原子机制的基本理解仅限于经验数据的过程优化，从而影响了催化剂的开发。在此背景下，表面科学方法已被证明具有通过提供指导催化材料工程的潜力。实际的然而，这些研究通常仅限于超高真空 (UHV) 条件，而工业化学过程发生在高压和复杂材料上。在这里，我们的目标是获得原子的机理见解。通过结合优化在高压下工作的原位表面科学方法，即高压扫描隧道显微镜 (HP-STM) 和近环境压力 X 射线光电子能谱，可将规模扩大到单点反应。 （NAP-XPS），我们将研究在实际反应条件下，从模型系统到工业负载催化剂的小烃单中心催化聚合的机制。首先，我们将阐明 Ni(111) 模型催化剂上的烃聚合，其中单个 Ni 吸附原子被建议充当 SAC，在毫秒时间尺度上进行的原位 STM 成像将有助于阐明它们在促进单体附着方面的作用。在毫巴范围内的压力下，通过 HP-STM 和 NAP-XPS，我们的目标是揭示在特高压下观察到的烃聚合过程如何向工业反应器常用的条件演变。然后，我们计划扩大现场研究用于烯烃聚合的“现实世界”负载型催化剂，即锚定在超薄氧化铝载体上的茂金属配合物。为此，我们将利用在受控条件下制备的明确的系统来制备。该策略将通过先进的原位显微镜和光谱技术进行表征，揭示反应机制并揭示现实反应条件下催化活性物质的性质。通过这种方式，我们的目标是澄清有关工业化学过程中单中心催化剂作用的长期存在的问题，对新催化剂的设计具有潜在影响。