Elucidating the Role of Basic Promoters in Transition Metal Catalysis

摘要：美国弗吉尼亚大学Robert J. Davis教授将研究碱土元素和稀土氧化物对负载型Ru金属催化剂在氨合成反应中的促进作用机理。这项建议与催化科学有关，并与化学工业，特别是与农用化学品和商品化学品生产有关的化学工业有更广泛的关系。在碱促进钌催化剂上合成氨可以降低工艺能耗，从而减少对环境的影响。Ru金属的碱性促进剂将包括碱和碱土以及稀土氧化物：例如，K、Ba、Ca和Ce和Pr的氧化物。支持物包括沸石、其他氧化物和碳。目的是用EXAFS测定Ru簇的原子结构，用XANES和吸附氮气的红外光谱测定其电子结构。在非沸石载体上的Ru簇附近和簇上的启动子分布将通过分析HRTEM进行检测，并与乙烷氢解活性相关。活性位点的密度将通过N2和H2化学吸附的TPD，以及它们在大气和20 bar压力下N2活化和NH3合成的固有活性来确定。各种反应中间体的表面覆盖将通过稳态同位素瞬态动力学进行研究。

Abstract- Davis - 9729812 Prof. Robert J. Davis of the University of Virginia will investigate the mechanism of promotion of supported Ru metal catalysts for the ammonia synthesis reaction, by alkaline-earth elements and rare-earth oxides. This proposal is of relevance to the science of catalysis and of wider relevance to the chemical industry, in particular that concerned with agrochemical and commodity chemical production. Ammonia synthesis over base-promoted Ru catalysts may lead to reduced consumption of process energy and consequently less environmental impact. Basic promoters for Ru metal will include alkali and alkaline-earth as well as rare-earth oxides: K, Ba, Ca, and oxides of Ce and Pr, for example. Supports will include zeolites, other oxides, and carbon. The proposal objectives are to determine the atomic structure of Ru clusters by EXAFS and their electronic structure by XANES and IR spectroscopy of adsorbed N2. The promoter distribution in the vicinity of, and on Ru clusters over non-zeolitic supports, will be examined by analytical HRTEM, and correlated with ethane hydrogenolysis activity. The density of active sites will be determined with TPD of N2 and H2 chemisorption, and their intrinsic activity by N2 activation and by NH3 synthesis at atmospheric and at 20-bar pressure. The surface coverage by various reactive intermediates will be investigated by means of steady state isotopic transient kinetics.