Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, 5600MB, Eindhoven, The Netherlands.
Phys Chem Chem Phys. 2013 Oct 28;15(40):17038-63. doi: 10.1039/c3cp52506f.
The increasing availability of quantum-chemical data on surface reaction intermediates invites one to revisit unresolved mechanistic issues in heterogeneous catalysis. One such issue of particular current interest is the molecular basis of the Fischer-Tropsch reaction. Here we review current molecular understanding of this reaction that converts synthesis gas into longer hydrocarbons where we especially elucidate recent progress due to the contributions of computational catalysis. This perspective highlights the theoretical approach to heterogeneous catalysis that aims for kinetic prediction from quantum-chemical first principle data. Discussion of the Fischer-Tropsch reaction from this point of view is interesting because of the several mechanistic options available for this reaction. There are many proposals on the nature of the monomeric single C atom containing intermediate that is inserted into the growing hydrocarbon chain as well as on the nature of the growing hydrocarbon chain itself. Two dominant conflicting mechanistic proposals of the Fischer-Tropsch reaction that will be especially compared are the carbide mechanism and the CO insertion mechanism, which involve cleavage of the C-O bond of CO before incorporation of a CHx species into the growing hydrocarbon chain (the carbide mechanism) or after incorporation into the growing hydrocarbon chain (the CO insertion mechanism). The choice of a particular mechanism has important kinetic consequences. Since it is based on molecular information it also affects the structure sensitivity of this particular reaction and hence influences the choice of catalyst composition. We will show how quantum-chemical information on the relative stability of relevant reaction intermediates and estimates of the rate constants of corresponding elementary surface reactions provides a firm foundation to the kinetic analysis of such reactions and allows one to discriminate between the different mechanistic options. The paper will be concluded with a short perspective section dealing with the needs for future research. Many of the current key questions on the physical chemistry as well as computational study of heterogeneous catalysis relate to particular topics for further research on the fundamental aspects of Fischer-Tropsch catalysis.
表面反应中间体的量子化学数据的日益丰富，促使人们重新审视多相催化中尚未解决的动力学问题。其中一个特别受关注的问题是费托合成反应的分子基础。在这里，我们综述了目前对该反应的分子理解，该反应将合成气转化为更长的碳氢化合物，特别阐明了由于计算催化的贡献而取得的最新进展。这一观点突出了旨在从量子化学第一性原理数据进行动力学预测的多相催化理论方法。从这个角度讨论费托合成反应很有趣，因为该反应有几种可能的反应机理。对于单体单 C 原子中间物的性质，以及生长碳氢链本身的性质，有许多关于该反应的建议。费托合成反应有两种主要的、相互矛盾的反应机理，将特别进行比较，这两种机理是碳化物机理和 CO 插入机理，它们涉及到在将 CHx 物种插入生长的碳氢链之前（碳化物机理）或插入生长的碳氢链之后（CO 插入机理）断裂 CO 的 C-O 键。选择特定的机理具有重要的动力学后果。由于它基于分子信息，它也会影响到这种特定反应的结构敏感性，从而影响催化剂组成的选择。我们将展示关于相关反应中间体相对稳定性的量子化学信息以及相应的基本表面反应速率常数的估计如何为这种反应的动力学分析提供坚实的基础，并允许在不同的反应机理之间进行区分。本文将以简短的展望部分结束，讨论未来研究的需求。目前关于多相催化的物理化学和计算研究的许多关键问题都涉及到费托催化基本方面的进一步研究的特定主题。
