UNS:Modeling Bulk Composition Dependent Alloy Surface Properties Under Reaction Conditions

由两种或多种金属的混合物组成的合金催化剂广泛用于商业应用中，以比单一金属更有效地促进反应。 然而，在设计新的催化剂时，很难预测两种或更多种金属的哪种组合对于给定的反应将是最有效的，特别是因为气-固催化反应中的活性表面位点通常在结构和组成上不同于本体合金的那些。 这项工作将开发一种改进的模型，用于预测合金催化剂在实际工作条件下的催化反应性，从而能够发现新的和改进的合金催化剂，而不需要昂贵和耗时的合成和测试大阵列的潜在金属组合。 这项工作解决了两个主要因素，阻碍直接相关的散装合金组合物与催化反应性：表面偏析和吸附剂引起的表面组成的变化。 具体而言，新的方面的研究是结合联合收割机的表面位置分布函数（其中每个网站的反应性是由密度泛函理论计算）与表面偏析模型（包括吸附诱导的影响），以产生一个统计加权平均性能的合金表面。 新的方法将被应用到优化的Ag-Pd合金的设计中，用于在乙烯存在下乙炔的选择性氢化-一个商业上重要的反应。本研究中开发的理论方法将对催化工业产生广泛的影响，通过比简单的试错法更有效地设计催化剂，并通过生产比目前使用的催化剂更具活性，选择性和能源效率的催化剂。 此外，研究人员将公开他们的方法提供给催化社区，既作为一种研究工具，也作为一种教育工具。

Kitchin, 1506770Alloy catalysts, consisting of mixtures of two or more metals, are widely used in commercial applications to promote reactions more effectively than possible with a single metal. However, in designing new catalysts, it is difficult to predict which combinations of two or more metals will be the most effective for a given reaction, especially because the active surface sites in gas-solid catalytic reactions typically are different in structure and composition than those of the bulk alloy. This work will develop an improved model for predicting the catalytic reactivity of alloy catalysts under actual working conditions, thereby enabling the discovery of new and improved alloy catalysts without the need for costly and time-consuming synthesis and testing of large arrays of potential metal combinations. The work addresses two major factors that hinder direct correlation of bulk alloy composition with catalytic reactivity: surface segregation and adsorbate-induced changes in surface composition. Specifically, the novel aspect of the study is to combine a surface site distribution function (where the reactivity of each site is calculated by density functional theory) with a surface segregation model (that includes adsorbate-induced effects) to produce a statistically weighted average property of the alloy surface. The new approach will be applied to the design of optimized Ag-Pd alloys for the selective hydrogenation of acetylene in the presence of ethylene - a commercially important reaction. The theoretical methods developed in this study will have broad impact to the catalysis industry by enabling more efficient design of catalysts than simple trial-and-error methods, and by producing catalysts that are more active, selective, and energy-efficient than catalysts currently in use. In addition, the researchers will make their methods openly available to the catalysis community, both as a research tool and as an educational tool.