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

摘要CTS-9525761这个项目使用分子方法来表征与汽车催化转化器用于环境控制的功能相关的催化过程的动力学细节。现代超高真空技术与常压催化反应器结合使用。用King和Wells的方法研究了一氧化碳在铂上的氧化和一氧化氮(一氧化碳或氧气)在铑上的还原反应。这些实验通过将底物暴露在混合气体中或通过在暴露于一种气体之前预先吸附另一种气体来模拟竞争吸附。所研究的气体物种是燃烧废气中的那些物质，包括水和二氧化碳。实验结果用蒙特卡罗计算机模拟器算法模拟。研究了甲烷在钯上的氧化反应。这项研究是基于汽车尾气控制中使用的催化系统的实验模型。然而，它也与其他(固定)燃烧系统排放的污染控制有关，包括发电厂、供暖系统、焚烧炉和蒸汽工厂。

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.