Modeling NOx Reduction on Catalytic Surfaces with Molecular Beam Techniques

该建议是弗朗西斯科扎埃拉教授关于燃烧废气在贵金属表面上的催化反应的研究的延续。Zaera教授的实验室专门使用分子束技术进行本征动力学测定，并使用表面红外振动光谱进行化学吸附表征。在先前的资助下，在高真空下观察到的动力学和机制与催化反应条件下观察到的动力学和机制之间的关联方面取得了进展。在本建议中，NO和CO在Pd（和Rh）单晶在高温下的反应将在高通量脉冲分子束条件下进行研究，以模拟真实的催化反应条件。此外，燃烧废气中典型的其它气体，例如，CO2、H2O、O2将被包括在分子束中，以确定竞争吸附对吸附截面和反应动力学的影响。快速步进扫描红外反射吸收光谱仪将提供随时间变化的表面覆盖度和成分信息。吸附机理将用蒙特-卡罗技术模拟，反应参数将从瞬态动力学研究中得出。该研究对开发新型燃烧废气治理催化剂具有重要意义。它被认为是遵守现代全球气体排放标准的首要需求。

This proposal is a continuation of Prof. Francisco Zaera's investigation of the catalytic reaction of combustion exhaust gases on noble metal surfaces. Prof. Zaera's laboratory is specialized in the use of molecular beam techniques for intrinsic kinetics determination, and surface infrared vibrational spectroscopy for chemisorbate characterization. Under the previous grant, progress was made in correlating between kinetics and mechanisms observed under high-vacuum to those under catalytic reaction conditions. In the present proposal, NO and CO reactions on Pd (and Rh) single crystals at high temperature will be studied under high-flux pulsed molecular beam conditions, to resemble the real catalytic reaction conditions. In addition, other gases typical in combustion exhaust, e.g., CO2, H2O, O2, will be included in the molecular beam in order to determine the influence of competitive adsorption on the adsorption cross-section and the reaction kinetics. A rapid step-scanning infrared reflection-absorption spectroscope will provide the time-dependent surface coverage and composition information. The mechanism of adsorption will be modeled with Monte-Carlo techniques and the reaction parameters will be derived from the transient kinetics study. This research has significant implications in the development of novel catalysts for the remediation of combustion exhaust gases. It is recognized as a primary need in complying with modern global standards of gas emission.