Mechanisms of Surface Hydrogenation Reactions

许多金属表面可以催化重要的化学反应。然而，催化活性最高的金属往往是一些最稀有和最昂贵的元素，如钯(Pd)和铂(Pt)。在化学系化学结构动力学和机理(CSDM-A)计划的支持下，伊利诺伊大学芝加哥分校的Michael Trenary教授正在探索一种新的双金属表面，在这种表面上，孤立的催化活性金属(如Pd)原子被放置在价格较低的金属(如铜)上。当这些单原子合金(SSA)暴露在氢气(H2)中时，Pd原子将H2分子解离成H原子，H原子溢出到铜表面。特伦纳里教授正在与他的学生们合作，使用精密的光谱仪来研究表面弱结合的氢原子与有机小分子之间的氢化反应。该项目可以促进我们对催化加氢反应的理解，并可能导致开发出最大限度地减少昂贵金属使用的新催化材料。该项目还在培养未来的科学家，并通过与日本研究人员的合作促进国际合作。该项目使用常压条件下的偏振相关反射吸收红外光谱(RAIRS)来表征加氢反应的基本步骤。通过红外光谱分析，特雷纳里教授和他的学生们监测了气相产物的演变，同时也表征了吸附的表面物种。将该方法应用于Pd-Ag(111)SAA催化剂上丙烯醛选择性加氢制2-丙烯醇和Pd-Cu(111)和Pd-Cu(111)SAAS催化剂上的CO2加氢反应。除了RAIRS实验外，还使用了各种其他技术来研究表面的性质及其氢化化学，包括程序升温反应光谱(TPRS)、俄歇电子能谱(AES)和扫描隧道显微镜(STM)。对于每个加氢反应，目标是获得关于反应中间体的身份的信息，并将它们与旁观者物种区分开来。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Many metal surfaces can catalyze important chemical reactions. However, metals with the highest catalytic activity are oftentimes some of the rarest and most expensive elements, such as palladium (Pd) and platinum (Pt). With support from the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Michael Trenary of the University of Illinois at Chicago is exploring a new class of bimetallic surfaces where isolated atoms of catalytically active metals (e.g. Pd) are placed on a less expensive metal, such as copper (Cu). When these single atom alloys (SSAs) are exposed to hydrogen gas (H2), the Pd atoms dissociate the H2 molecules into H atoms, which spillover onto the Cu surface. Working with his students, Professor Trenary is using sophisticated spectroscopies to study hydrogenation reactions between the weakly bound H atoms on the surface and small organic molecules. The project could advance our understanding of catalytic hydrogenation reactions, and could lead to the development of new catalytic materials that minimize the use of expensive metals. The project is also training future scientist and fostering international cooperation through collaboration with researchers in Japan.The project is using polarization dependent reflection absorption infrared spectroscopy (RAIRS) under ambient pressure conditions to characterize the fundamental steps of hydrogenation reactions. Through analysis of the infrared spectra, Professor Trenary and his students monitor the evolution of gas phase products while also characterizing adsorbed surface species. The methodology is applied to the selective hydrogenation of acrolein to 2-propenol over a Pd-Ag(111) SAA and to CO2 hydrogenation over Pd-Cu(111) and Pt-Cu(111) SAAs. In addition to RAIRS experiments, the properties of the surfaces and their hydrogenation chemistry are being studied with a variety of other techniques including temperature programmed reaction spectroscopy (TPRS), Auger electron spectroscopy (AES), and scanning tunneling microscopy (STM). For each hydrogenation reaction, the objective is to obtain information on the identity of reaction intermediates and to distinguish them from spectator species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.