Theoretical studies of acrolein hydrogenation on silver catalysts

该项目将寻求在微观层面上澄清银催化剂在a，b-不饱和醛加氢生产技术上重要的不饱和醇中的高选择性的原因。为此，高层次的密度泛函计算丙烯醛分子（作为一个代表性的反应物），吸附在各种银基板，以及中间体，过渡态，和氢化反应的产物将进行。参与两个竞争的反应途径，丙烯醛的C=O和C=C键的氢化的表面络合物，将被研究。可以被“真实的”银催化剂暴露的规则小面将由单晶（111）、（100）和（110）Ag表面模拟。表面的不规则性将表示为平板模型的阶梯银表面以及银纳米团簇。研究的主题可以分为以下几类：1）丙烯醛及其加氢反应的中间体和产物在Ag基底上的吸附; 2）在存在共吸附在表面上和/或溶解在亚表面区域中的原子氢的情况下的相同吸附系统; 3）选择的过渡态的位置以量化丙烯醛加氢的活化能势垒。这个理论项目将补充P. Claus（达姆施塔特工业大学）和R. Schlögl/A. Knop-Gericke（FHI柏林）。

The project will seek to clarify at the microscopic level reasons for the high selectivity of silver catalysts in the hydrogenation of a,b-unsaturated aldehydes to produce technologically important unsaturated alcohols. For this purpose, high-level density functional calculations of acrolein molecules (as a representative reactant), adsorbed on various Ag substrates, as well as of intermediates, transition states, and products of the hydrogenation reactions will be carried out. Surface complexes involved in the two competing reaction pathways, hydrogenation of the C=O and C=C bonds of acrolein, will be studied. Regular facets that can be exposed by "real" silver catalysts will be modeled by single crystal (111), (100) and (110) Ag surfaces. Surface irregularities will be represented by slab models of stepped Ag surfaces as well as by Ag nanoclusters. The topics of the studies can be grouped as follows: 1) adsorption of acrolein, intermediates and products of its hydrogenation reactions on Ag substrates; 2) the same adsorption systems in the presence of atomic hydrogen co-adsorbed on the surface and/or dissolved in the subsurface region; 3) location of selected transition states to quantify activation energy barriers of acrolein hydrogenation. This theoretical project will supplement experimental efforts within the priority programme by the groups of P. Claus (TU Darmstadt) and R. Schlögl/A. Knop-Gericke (FHI Berlin).