Acetylene Hydrogenation on Alloy Catalysts Spanning Ternary Alloy Composition Space

催化剂用于加速工业过程中化学品的生产，大大提高了生产效率，并在化学制造中提供了显著的节能。多组分合金，即两种或两种以上金属的均匀混合物，在这些反应中用作催化剂，因为它们比任何纯金属成分本身都更有效。相对金属成分在很大范围内是可变的，这对设计合金催化剂提出了挑战，即如何找到每种金属成分的最佳相对量以获得最大的催化剂效率。这可能成为一项繁琐而耗时的研究活动，因为它需要制备、表征和催化评估数百种不同的合金催化剂，每种催化剂都有不同的组成。Gellman博士发明了一种快速，高通量的方法来加速研究三组分（三元）合金催化剂的广泛可能组成。Gellman博士制造了一种单一材料，其合金成分沿着材料表面连续变化。然后，他使用了一些最先进的空间分辨分析工具。每次测量都探测不同成分的催化剂合金。该方法允许一次制备100种催化剂组合物，然后在顺序制备每种组合物所允许的时间的一小部分内进行表征和研究。Gellman博士正在使用他的高通量方法来了解合金催化剂的组成如何影响乙炔（HCCH）加氢成乙烯（H2CCH2）的动力学和选择性，这是聚合物生产中的一个重要化学过程。最终，Gellman博士的工作可能会改善合金催化剂的许多应用，并可能为清洁能源技术做出贡献，因为它与碳氢化合物转化有关。除了他在催化领域的进步，Gellman博士在他与学生的工作中产生了更广泛的影响。他指导女本科生进行研究，以鼓励她们在STEM领域攻读高级学位的兴趣。作为卡内基梅隆大学斯科特能源创新研究所的联合主任，他还从事公共教育活动。了解多组分合金催化剂的复杂性是由于测量合金材料的物理特性和催化活性作为多维成分的函数的实验挑战。卡内基梅隆大学的Andrew Gellman博士在化学学部的化学催化项目和化学、生物工程、环境和运输系统学部的催化和生物催化项目的资助下，通过使用他实验室开发的一套独特的高通量方法来解决这一挑战。该分析采用了一种合金薄膜，其中包含所有可能的合金成分，该过程称为成分扩散合金薄膜（CSAF）。制备了三元合金CuxAuyPd1-x-y、CuxAgyPd（1-x-y）和AgxAuyPd(1-x-y)，其中x和y在整个成分范围内变化，样品尺寸约为1 cm2。利用空间分辨表面分析工具绘制合金特征图，包括体积成分、表面成分和价电子结构，并将其作为成分空间的函数。然后使用一个独特的100通道微反应器阵列，在100种不同的合金成分下，对HD交换、乙烯加氢和乙炔加氢等几种催化过程的动力学和选择性进行平行测量。采用微动力学分析方法提取了基本反应步骤的基本参数。这些测量建立了动力学参数和合金特性之间的相关性，并深入了解了各个基本步骤与合金成分的速率依赖关系。除了他在催化领域的进步，Gellman博士在他与学生的工作中产生了更广泛的影响。他指导本科女生进行研究，鼓励她们在STEM领域攻读高级学位的兴趣。作为卡内基梅隆大学斯科特能源创新研究所的联合主任，他还从事公共教育活动。

Catalysts are used to accelerate production of chemicals in industrial processes, greatly increasing the efficiency of production and providing significant energy savings in chemical manufacturing. Multicomponent alloys, homogeneous mixtures of two or more metals, are used as catalysts in these reactions because they are more effective than any of the pure metal components by itself. The relative metal compositions are variable over a wide range, which presents a challenge in designing alloy catalysts in finding the optimal relative amounts of each metal component for maximum catalyst efficiency. This can become a tedious and time-consuming research activity because it requires the preparation, characterization and catalytic evaluation of hundreds of different alloy catalysts, each with a different composition. Dr. Gellman has invented a rapid, high-throughput method to accelerate the study of three-component (ternary) alloy catalysts over a wide range of possible compositions. Dr. Gellman fabricates a single material in which the composition of the alloy is varied continuously along the material surface. He then uses a number of state-of-the-art spatially-resolved analytical tools. Each measurement probes a catalyst alloy with a different composition. This methods allows 100 catalyst compositions to be prepared at once, then characterized and studied in a fraction of the time that sequential preparation of each composition would allow. Dr. Gellman is using his high-throughput method to understand how the composition of alloy catalysts influences the kinetics and selectivity of acetylene (HCCH) hydrogenation to ethylene (H2CCH2), an important chemical process in polymer production. Ultimately, Dr. Gellman's work may lead to improvement of alloy catalysts for numerous applications and may contribute to clean energy technologies for its relevance to hydrocarbon conversion. In addition to his advancement of the field of catalysis, Dr. Gellman is making broader impacts in his work with students. He mentors female undergraduate students in research to encourage their interest in pursuing advanced degrees in the STEM fields. He also is engaged in public education activities as part of his role as co-Director of the Carnegie Mellon University's Scott Institute for Energy Innovation.Understanding the complexity of multicomponent alloy catalysts is confounded by the experimental challenges of measuring the physical characteristics and the catalytic activities of alloy materials as a function of multidimensional composition. With funding from the Chemical Catalysis Program of the Chemistry Division and the Catalysis and Biocatalysis Program of the Division of Chemical, Bioengineering, Environment and Transport Systems Division, Dr. Andrew Gellman of Carnegie Mellon University addresses this challenge by using a unique set of high-throughput methods developed in his lab. The analysis employs an alloy film containing all possible compositions of alloys in a process called Composition Spread Alloy Films (CSAF). Ternary alloys, CuxAuyPd1-x-y, CuxAgyPd(1-x-y), and AgxAuyPd(1-x-y), are fabricated with x and y varied over the entire compositional range within an approximately 1 cm2 area sample size. Spatially resolved surface analysis tools are used to map alloy characteristics, including bulk composition, surface composition and valence electronic structure, as a function of composition space. A unique, 100 channel microreactor array is then used to make parallel measurements of the kinetics and selectivities of several catalytic processes, HD exchange, ethylene hydrogenation and acetylene hydrogenation, at 100 different alloy compositions. Microkinetic analysis is used to extract the fundamental reaction parameters for elementary mechanistic steps. These measurements establish correlations among kinetic parameters and alloy characteristics and yield insight into rate dependence of individual elementary steps with alloy composition. In addition to his advancement of the field of catalysis, Dr. Gellman is making broader impacts in his work with students. He mentors undergraduate female students in research to encourage their interest in pursuing advanced degrees in the STEM fields. He also is engaged in public education activities as part of his role as co-Director of the Carnegie Mellon University's Scott Institute for Energy Innovation.