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

该提案描述了在另一种化学物质和过量氧气存在下MnOx/TiO2表面CO活化的基本理解的研究计划。本研究侧重于CO不被氧化为CO2（非选择性），而是被用于选择性化学转化的反应的具体情况。这项工作的灵感来自于我们使用CO作为将NO转化为二氮的还原剂的显著发现。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°C和非常高的空速（GHSV = 50,000 h-1）下，NO转化率超过90%。在有氧存在的情况下，反应的活性增加，反应在有氧存在的情况下具有高度选择性。我们的原位FT-IR研究表明，MnOx/TiO2的反应机制与之前报道的负载金属和钙钛矿催化剂不同，因为不形成-NCO物种，这是广泛报道的中间产物。在2178 cm-1处没有明显的吸收带，证实了-NCO的不形成。一个平衡程序的合成，表征与现代技术，动力学研究，以揭示反应途径/机理的催化剂将进行。预计该研究将为在150至350°C的高浓度氧气条件下，在Mn/TiO2催化剂上，NO存在下CO活化过程中的表面化学和反应途径提供基本的理解。我们的研究将集中在CO与NO的反应上，后者的化合物作为观察到的选择性转化的促进剂。Mn在低温条件下的选择性和活性增加以及对水的高耐受性的具体作用将被深入研究。广泛的表面表征、动力学和同位素标记研究将进行实验来解释观察到的显著选择性。此外，这些工具将用于获得有用的见解Mn在活化CO和NO中的作用，了解中间表面物质的性质，并将确定表面物质在反应机制中的作用。所提出的研究在环境和能源方面具有独特的实际意义，这是对未来非常重要的领域。预计拟议的工作将对科学知识库、教育和整个社会产生广泛影响。最重要的驱动因素是制定更有效的环境过程，以及发展新的技术概念，推动目前使用CO催化的最新技术。预计对教育的影响将是多方面的。通过为高中学生开发创新的实践演示，在社区一级进行海报展示和展示，以及为工业界和学术界举办多学科研讨会，将广泛的选民引入该领域。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。将特别强调征聘代表性不足的少数民族和妇女。拟议的工作具有潜在的高社会经济影响。如果获得资金，它将提供先进的催化剂，更经济地控制空气污染。此外，将把在选择性转化一氧化碳方面获得的知识推广到其他重要的环境和能源过程。

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.