EAGER:GOALI: Bulk Intermetallics with well-defined active sites for selectivity control in selective hydrogenations

本研究项目研究了一种新型的多相催化剂，用于轻烃选择加氢反应，生成对石油化工有价值的高价值化学中间体。选择性是指当可能有多种产品时，催化剂优先于另一种产品的能力。因此，可以通过改变催化剂的表面组成来控制选择性。这项研究项目研究了一类无机固体，金属间化合物，它由不同大小和组成的小金属团簇有序组装而成。这些金属间化合物具有作为重要碳氢加氢反应的高选择性催化剂的潜力。计算研究和实验研究正在结合起来，以确定对所需产品既表现出高催化活性又表现出高选择性的催化剂成分。结晶学上定义明确的金属间化合物正被用来了解催化活性金属原子成核对催化选择性的影响。正在合成不同成分的金属间化合物，以控制原子核和团簇的数量。金属间化合物的形式M-锌(M=Pd，铜和银)已被仔细选择，因为它们包含连续的团簇尺寸的催化金属从单体到六聚体。在混合原料(炔烃+烯烃和烯烃+芳烃)的部分加氢反应中，正在研究M-Zn块状金属间化合物。实验结果将验证团簇大小对催化剂选择性的影响。结果可以用来确定氢化的选择性团簇尺寸，然后这些团簇将成为高比表面积纳米颗粒形式的合成目标。这项研究是与一个工业合作伙伴(埃克森美孚)合作进行的，该合作伙伴提供使用基于同步加速器的X射线吸收催化剂表征工具的机会，同时也为参与该项目的研究生提供与工业相关的指导。

This research project investigates a new class of heterogeneous catalysts for the selective hydrogenation reactions of light hydrocarbons to higher-value chemical intermediates of value to the petrochemical industry. Selectivity refers to the ability of a catalyst to favor one product over another when multiple products are possible. As such, it is possible to control selectivity by changing the surface composition of a catalyst. This research project investigates a class of inorganic solids, intermetallic compounds, that have ordered assemblies of small metal clusters of various size and composition. These intermetallic compounds have potential as highly selective catalysts for important hydrocarbon hydrogenation reactions. Computational studies and experiment studies are being combined to identify catalyst compositions that display both high catalytic activity and high selectivity toward the desired products. Crystallographically well-defined intermetallic compounds are being utilized to understand the impact of catalytically-active metal atom nuclearity on catalytic selectivity. Intermetallic compounds are being synthesized with varying compositions across the gamma-brass phase to control both nuclearity and the number of clusters. Intermetallics of the form M-Zn (M = Pd, Cu and Ag) have been carefully chosen since they contain contiguous cluster sizes of catalytic metal from monomers to hexamers. M-Zn bulk intermetallics are being examined for partial hydrogenation reactions of mixed feedstocks (alkyne plus alkene and alkene plus aromatic). The results will demonstrate the impact of cluster size on catalyst selectivity. The results can be used to identify selective cluster sizes for hydrogenation that will then become targets for synthesis in a high surface area nanoparticle form. The study is being conducted in collaboration with an industrial partner (ExxonMobil) who provides access to synchrotron-based X-ray absorption catalyst characterization tools, while also delivering industrially-relevant guidance to the graduate students involved in the project.