Activation of CO and NO Over MnOx/TiO2 Surfaces: Mechanistic Investigations

CBET-0828226 Smirnios这项建议描述了在存在另一种化学物种和过量氧的情况下，基本了解MnOx/Ti02表面上CO活化的研究计划。这项研究侧重于In CO不被氧化成CO2(非选择性)，但更多地用于选择性化学转化的特定反应情况。这项工作的灵感来自于我们使用CO作为还原剂将NO转化为二氮的显着发现。更具体地说，我们发现MnOx/TiO2催化剂对CO还原NO具有很高的活性，在200℃下，在很高的空速(GHSV=50000 h-1)下，NO的转化率超过90%。在有氧的情况下，反应的活性增加，在有氧的情况下，反应具有高度的选择性。我们的原位FT-IR研究表明，MnOx/TiO2上的反应机理不同于先前报道的负载型金属和钙钛矿基催化剂，这是因为没有生成被广泛报道的中间体-NCO物种。在2178 cm-1处没有明显的吸收带，证实了-NCO物种的未形成。将进行一项平衡的合成计划，用现代技术进行表征，并进行动力学研究，以揭示所建议的催化剂上的反应途径/机理。预计拟议的研究将从根本上了解在150至350°C的范围内，在高浓度氧存在的情况下，在NO存在的情况下，在Mn/Ti02催化剂上CO活化过程中发生的表面化学和反应途径。我们的研究将集中在CO和NO的反应上，后者是选择性转化的促进剂。将深入研究锰在低温下提高选择性和活性以及对水的高耐受性的具体作用。将进行广泛的表面表征、动力学和同位素标记实验来解释观察到的显著选择性。此外，这些工具将被用来获得关于锰在活化CO和NO中的作用的有用的见解，了解中间表面物种的性质，并将识别表面物种在反应机理上的作用。拟议的研究对环境和能源这两个对未来非常重要的领域具有独特的实际意义。这项拟议的工作预计将对科学知识库、教育和整个社会产生广泛影响。压倒一切的驱动因素既是更有效的环境过程的制定，也是发展新的技术概念，以促进使用CO催化的当前最先进的技术。预计对教育的影响是多方面的。通过为高中生开展创新的动手演示，在社区一级进行海报展示和展示参与，以及为工业界和学术界举办多学科研讨会，将向该领域引入广泛的支持者。本科生将参与研究，以鼓励创新并激发对研究生教育的兴趣。将特别重视招聘任职人数不足的少数群体和妇女。这项拟议的工作可能会产生很高的社会经济影响。如果获得资金，它将提供先进的催化剂，更经济地运行，以控制空气污染。此外，在选择性转化CO方面获得的知识将扩展到其他重要的环境和能源相关过程。

CBET-0828226 SmirniotisThis proposal describes research plans for the fundamental understanding of CO activation over the surface of MnOx/TiO2 in the presence of another chemical species and excess oxygen. This study focuses on specific cases of reactions where in CO is not oxidized to CO2 (non-selective) but it is rather utilized towards a selective chemical transformation. This work is inspired by our remarkable findings of using CO as a reductant for the transformation of NO into di-nitrogen. More specifically, we found that the MnOx/TiO2 catalyst is highly active for the reduction of NO with CO, giving more than 90% NO conversion at 200 °C at very high space velocity (GHSV = 50,000 h-1). The activity of the reaction increased in presence of oxygen and the reaction is highly selective in the presence of oxygen. Our in-situ FT-IR studies revealed that the reaction mechanism on MnOx/TiO2 is different from that reported earlier over supported metal and perovskites-based catalysts, on account of the non-formation of -NCO species, which is widely reported as intermediate. The non-formation of -NCO species was confirmed by the absence of prominent absorbance band at 2178 cm-1. A balanced program for the synthesis, characterization with modern techniques, and kinetic studies to reveal the reaction pathways/mechanism over the proposed catalysts will be performed. It is expected that the proposed research will provide a fundamental understanding of the surface chemistry and reaction pathways occurring during the activation of CO in the presence of NO over Mn/TiO2 catalysts in the range of 150 to 350 °C in the presence of high concentrations of oxygen. Our studies will focus on reactions of CO with NO, where the latter compounds serve as a promoter for the selective transformations observed. The specific role of Mn leading to the increased selectivity and activity observed at low temperatures, and high tolerance to water will be investigated thoroughly. Extensive surface characterizations, kinetic and isotopic labeling studies experiments will be carried to explain the remarkable selectivity observed. Moreover, these tools will be used to obtain useful insights for the role of Mn in activating CO and NO, understand the nature of the intermediate surface species, and will identify the role of surface species on the reaction mechanism. The proposed research has unique practical implications in relation to environment and energy which are areas of great importance for the future. The proposed work is expected to broadly impact the scientific knowledge base, education, and society in general. The overriding drivers are both the formulation of more effective environmental processes, and developing new technological concepts that advance the current state-of-the-art in catalysis using CO. The impact on education is expected to be manifold. Through the development of innovative hands-on demonstrations for high school students, poster presentations and showcase participation at the community level, and multidisciplinary seminars to industry and academia, a broad constituency will be introduced to the field. Undergraduate students will be involved in the research, to encourage innovation and spark an interest in graduate education. A particular emphasis will be placed on recruiting under-represented minorities and women. The proposed work has potentially high socioeconomic impact. If funded it will provide advanced catalysts more economic to operate for air pollution control. Moreover, the knowledge gained on selectively transforming CO, will be extended to other important environmental and energy related processes.