Catalytic reactions studied by angle-resolved product desorption
Catalytic reactions studied by angle-resolved product desorption
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通过角分辨产物解吸研究催化反应
DOI：
10.1039/9781849732772-00139
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Kosuke Shobatake
中科院分区：
文献类型：
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作者：
Tatsuo Matsushima;Kosuke Shobatake
自1925年Taylor提出活性中心理论以来，催化化学的主要目标一直是确定和设计活性反应位点。位点的活性并不总是均匀的，甚至在无缺陷的表面上也是如此，并且只有有限的位点对关键过程（例如，限速步骤）是活性的。2只有有限的吸附物种可以参与反应途径。因此，活性位点和中间体必须通过反应本身直接鉴定，除了通过合适的表面光谱测量它们的静态特征之外。虽然许多化学动力学模拟3和光谱表面物种分配已被使用，4没有合适的方法已经建立了直接识别的反应位点，因为缺乏信息的新生的表面产品之前的能量耗散。最近，角分辨产物解吸分析已被公认为是直接的方法之一，网站的产品形成或活性中间体发射片段。5，6该方法基于能量耗散前的乘积分析和角度分解方法。另一方面，前者的动力学和光谱分析产品和中间体，无论是没有注意到他们的能量或能量耗散后。这种差异是必不可少的直接方法的网站或中间体，经常看到在气相反应的研究，其中产品进行分析之前，能量耗散。[7]在表面反应中，众所周知的从新生产物到金属表面的快速能量转移导致了这样一种情况，即主要从化学动力学的观点来研究反应。事实上，这种能量转移在金属表面上以皮秒的量级完成，到那时，通过表面光谱学观察到的物质已经被热化到表面温度。8此外，即使在400 K左右的物理吸附中，捕获物质的表面停留时间也很长，大约为纳秒。新生产物一旦被捕获在金属表面上，在解吸之前完全热化至表面温度。一般来说，从实验的角度来考察表面反应中的过渡态（TS）构象仍然是困难的。密度泛函理论（DFT）与广义梯度近似（GGA）已经产生了许多建议TS配置，例如，但是，没有实验验证已提供。9、10目前，还没有确定金属表面上新生产物的能量分布的方法。因此，对于直接的a催化研究中心，北海道大学，北21西10，札幌001-0021，日本b国际规划与合作总部，名古屋大学，筑草区，名古屋，
The main goal of catalysis chemistry has been to identify and design active reaction sites since the proposal of an active center theory by Taylor in 1925.1 This concept is still valid even on well-defined single crystal surfaces. The activity of sites is not always homogeneous, not even on defect-free surfaces, and only limited sites are active to key processes, for example, a rate-limiting step. 2 Only limited adsorbed species can participate in the reaction pathway. Thus, active sites and intermediates must be directly identified through the reaction itself, in addition to surveying their static features by means of suitable surface spectroscopy. Although many chemical-kinetic simulations3 and spectroscopic surface-species assignments have been used, 4 no suitable methods have been established for the direct identification of reaction sites because of the lack of information of nascent surface products before energy dissipation. Recently, angle-resolved product desorption analysis has been recognized as one of the direct approaches to sites for product formation or to active intermediates emitting fragments. 5, 6 This method is based on product analysis before energy dissipation and in angle-resolved ways. On the other hand, the former kinetics and spectroscopy analyze products and intermediates either without cautions toward their energy or after energy dissipation. This difference is essential for a direct approach to sites or intermediates as frequently seen in gas-phase reaction studies, in which products are analyzed before energy dissipation. 7 In surface reactions, the well-known rapid energy transfer from nascent products to metal surfaces has brought about a situation in which reactions are primarily studied from the viewpoint of chemical kinetics. In fact, this energy transfer is completed on the order of picoseconds on metal surfaces, by which time species observed by surface spectroscopy have already been thermalised to the surface temperature. 8 In addition, the surface residence time of trapped species is long, on the order of nanoseconds, even in physical adsorption at around 400 K. Nascent products once trapped on metal surfaces are completely thermalised to the surface temperature before desorption. Generally speaking, it remains difficult to examine the transition state (TS) conformation in a surface reaction from an experimental viewpoint. The density functional theory (DFT) with a generalized gradient approximation (GGA) has yielded many proposals for TS configurations, for example; however, no experimental verification has been provided. 9, 10 At present, there is no method for determining the energy distributions of nascent products on metal surfaces. Thus, only limited surface reactions, which emit product molecules with hyperthermal energy, have been examined for the direct aCatalysis Research Center, Hokkaido University, North 21 West 10, Sapporo 001-0021, Japan bInternational Planning & Cooperation Headquarter, Nagoya University, Chikusa-ku, Nagoya,