Kinetic Measurements of Catalytic Converter Reactions by Using Modern Surface Sensitive Techniques

摘要CTS-9525761 该项目采用分子方法来表征与汽车催化转化器的环境控制功能相关的催化过程的动力学细节。 现代超高真空技术与大气压催化反应器结合使用。 本文用King和威尔斯的方法研究了一氧化碳在铂表面上的氧化和一氧化氮在铑表面上的还原（用一氧化碳或氧），方法是用质谱仪记录气体的分压，同时用准直的气体束直接撞击表面，测量粘附系数和反应速率。 实验通过将基底暴露于气体物质混合物或在暴露于另一种物质之前预吸附一种物质来模拟竞争吸附。 研究的气体种类是燃烧废气中的那些，包括水和二氧化碳。 实验结果采用Monte Carlo计算机模拟算法进行建模。 研究了甲烷在钯催化剂上的氧化反应。 这项研究是基于实验模型的催化系统用于汽车排气控制。 然而，它也与来自其他（固定）燃烧系统（包括发电厂、加热系统、焚化炉和蒸汽厂）的排放物的污染控制有关。

ABSTRACT CTS-9525761 This project employs a molecular approach to characterize the kinetic details of catalytic processes relevant to the functioning of automotive catalytic converters for environmental control. Modern ultrahigh-vacuum techniques are used in conjunction with atmospheric-pressure catalytic reactors. The oxidation of carbon monoxide on platinum and the reduction of nitric oxide (by carbon monoxide or oxygen) on rhodium are studied by measuring sticking coefficients and reaction rates using the method of King and Wells in which the partial pressures of the gases are recorded with a mass spectrometer while a collimated gas beam impinges directly on the surface. The experiments emulate competitive adsorption either by exposing the substrate to a mixture of gas species or by preadsorbing one species before exposure to another. Gaseous species studied are those in combustion exhaust, including water and carbon dioxide. Experimental results are modeled using a Monte Carlo computer simulator algorithm. The oxidation of methane over palladium is also studied. This study is based on experimental models for the catalytic systems used in automotive exhaust control. However, it is also relevant to pollution control of emissions from other (stationary) combustion systems including power plants, heating systems, incinerators, and steam plants.