Surface reactivity of polycyclic aromatic hydrocarbon clusters
Surface reactivity of polycyclic aromatic hydrocarbon clusters
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DOI：
10.1016/j.proci.2014.06.140
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发表时间：
2015-01-01
影响因子：
3.4
通讯作者：
Kraft, Markus
中科院分区：
文献类型：
--
作者：
Chen, Dongping;Akroyd, Jethro;Kraft, Markus
提出了一种表征表面原子的方案，以探测均相芘和冠烯簇的分子表征。溶剂排除表面的概念，广泛用于蛋白质，形成了该方案的基础。该方案用于根据不同气体种类的活性原子和位置的表面可用性提供对表面反应性的见解。研究发现，活性位点的表面有效性随气体种类、体系温度和颗粒大小而变化。小气体种类的活性位点数量总是大于大气体种类的活性位点数量。表面暴露量随温度的升高而增加，当转变为类液体形态时，表面暴露量明显增强。表面可用性随粒径的增大而降低，并与粒径的倒数呈线性关系。烟灰文献中用于经验量化表面反应性的参数a，在HACA机制的背景下进一步估计，烟灰颗粒与乙炔之间反应的参数a约为0.8，与0.9相似。通过探索具有100个分子的冕烯团簇表面的一个特定口袋，发现氧和乙炔分子原则上都可以穿透团簇内部。然而，与表面反应的时间尺度相比，单个口袋的寿命非常短，从而排除了表面反应可以通过表面口袋在边界以外的区域发生的可能性。(C) 2014燃烧研究所。Elsevier Inc.出版。版权所有。
A scheme to characterise surface atoms is proposed to probe molecular representations of homogenous pyrene and coronene clusters. The concept of solvent-excluded surface, which is widely used for proteins, forms the basis of this scheme. The scheme is used to provide insights into the surface reactivity in terms of the surface availability of active atoms and sites for different gaseous species. It was found that the surface availability of active sites varies with gaseous species, system temperature and particle size. The number of active sites available for a small gaseous species is always greater than that for a large species. Surface exposure increases with an increase in temperature and an obvious enhancement exists when transforming to liquid-like configurations. The surface availability decreases with increasing particle size following a linear relation with reciprocal size. The parameter a, which is used in the soot literature to empirically quantify surface reactivity, was further estimated in the context of HACA mechanism and was approximately 0.8 similar to 0.9 for reactions between soot particles and acetylene. By exploring one particular pocket on the surface of a coronene cluster with 100 molecules, it was noted that it is feasible for both oxygen and acetylene molecules to penetrate inside the cluster in principle. However, the lifetime of individual pockets was found to be very short compared to the time-scale of a surface reaction, thus ruling out the possibility that surface reactions can take place in regions beyond the boundary by means of surface pockets. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.