Understanding the Mechanism of Plasma-assisted Catalysis: Visit by Prof. Y.S. Mok

这项建议旨在寻求支持，使来自韩国济州大学的莫永生教授能够在他的休息年与曼彻斯特大学化学学院的等离子体化学小组合作进行调查。莫教授在等离子体辅助催化净化环境，特别是脱除柴油废气中的氮氧化物方面，是一位经验丰富的研究人员。拟议调查的目的是研究等离子体放电和催化剂相结合如何提高两个过程的效率，以销毁废气中的VOCs和NOx等污染物。废气中的等离子体放电产生高能电子，这些电子继续产生激发的原子、分子和自由基。然后，这些物种会启动一系列化学反应，摧毁污染物，理想的情况是将它们转化为无害的化合物，这些化合物可以安全地排放到大气中，或者转化为可以去除并可能回收利用的化合物。结果发现，等离子体和催化的结合提高了催化剂的破坏效率，降低了催化剂的工作温度，在某些情况下接近环境温度。与单独操作催化剂相比，这可以带来十分之一的能源消耗减少。然而，等离子体放电激活催化剂的过程的机理尚不清楚。它可能涉及等离子体产生的电子和光子与催化剂表面的相互作用，或者产生的自由基被吸附到催化剂上，并开辟新的反应途径。或者，等离子体可以在与催化剂相互作用之前通过化学反应简单地改变气体的性质。我们将使用一系列催化材料和不同的等离子体放电配置进行一系列实验，使用现有气流的在线化学分析来了解过程的化学成分，并确定涉及的关键参数。对等离子体活化催化的温度依赖性的研究将产生包括活化能在内的动力学信息。将使用一系列分析和表面表征技术来研究加工后催化剂的任何变化，这将产生所涉及的表面物种的信息。将开发一个基于计算机的模型，该模型结合了气相和非均相化学以及等离子体的电学性质和气体动力学。人们希望这个模型将确定等离子体辅助催化中涉及的关键过程，使我们能够通过建模来开发基本的分子机制，既可以用于解释模式，也可以用于预测模式。

This proposal seeks support to enable Professor YS Mok from Cheju University in Korea to spend his sabbatical year in a collaborative investigation with the Plasma Chemistry group in the School of Chemistry at The University of Manchester. Professor Mok is an experienced researcher working in the field of plasma-assisted catalysis for environmental clean-up, particularly the removal of NOx from diesel exhaust. The purpose of the proposed investigation is to study the mechanism by which combining a plasma discharge with a catalyst increases the efficiency of both processes for the destruction of pollutants such as VOCs and NOx in waste gas streams. The plasma discharge in the waste gas creates highly energetic electrons which go on to create excited atoms, molecules and radicals. These species then initiate a series of chemical reactions that destroy the pollutants, ideally converting them into benign compounds which can be safely vented to atmosphere or into compounds that can be removed and possibly recycled. It is found that the combination of plasma and catalysis increase the destruction efficiency of the catalyst reducing its operating temperature in some cases close to ambient. This can bring about a factor of ten reduction in the energy consumption compared to the operation of the catalyst alone. However, the mechanism of the processes by which the plasma discharge activates the catalyst is not clearly understood. It might involve interaction of plasma-generated electrons and photons with the catalyst surface or radicals are produced which are adsorbed onto the catalyst and open up new reaction pathways. Alternatively, the plasma may simply change the nature of the gas by chemical reaction before interaction with the catalyst. We will conduct a series of experiments with a range of catalytic materials and different plasma discharge configurations using on-line chemical analysis of the exiting gas stream to understand the chemistry of the process and to determine the key parameters involved. Studies of the temperature dependence of the plasma-activated catalysis will yield kinetic information including activation energies. A range of analytical and surface characterisation techniques will be used to study any changes in the catalysts following processing which will yield information on the surface species involved. A computer-based model that incorporates the gas-phase and heterogeneous chemistry together with the electrical properties of the plasma and the gas dynamics will be developed. It is hoped that this model will identify the key processes involved in plasma-assisted catalysis allowing us to develop fundamental molecular mechanisms via the modelling that can be used both in an interpretative and predictive mode.