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

MnOx/TiO2 表面上 CO 和 NO 的活化：机理研究

• 批准号: 0828226
• 负责人: Panagiotis Smirniotis
• 金额: $ 30万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0828226&HistoricalAwards=false
• 关键词: Activation; CO; NO; Over; MnOx

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.

CBET-0828226 Smirniotis该提案描述了在另一种化学物质和过量氧气存在下MnOx/TiO 2表面上CO活化的基本理解的研究计划。这项研究的重点是在CO不氧化为CO2（非选择性），而是利用对选择性的化学转化反应的具体情况。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，我们发现MnOx/TiO 2催化剂对于用CO还原NO具有高活性，在200 ℃下在非常高的空速（GHSV = 50，000 h-1）下产生超过90%的NO转化率。在氧气存在下，反应的活性增加，并且反应在氧气存在下是高度选择性的。我们的原位FT-IR研究表明，MnOx/TiO 2上的反应机理与先前报道的负载型金属和钙钛矿基催化剂不同，因为不形成-NCO物种，这被广泛报道为中间体。通过在2178 cm-1处不存在显著的吸收带证实了-NCO物质的未形成。一个平衡的程序的合成，表征与现代技术，动力学研究，以揭示在拟议的催化剂的反应途径/机制将进行。预计拟议的研究将提供在150至350 °C的范围内，在高浓度氧气的存在下，在Mn/TiO 2催化剂上，在NO的存在下活化CO期间发生的表面化学和反应途径的基本理解。我们的研究将集中在CO与NO的反应，后者的化合物作为观察到的选择性转化的促进剂。将彻底研究Mn导致在低温下观察到的增加的选择性和活性以及对水的高耐受性的具体作用。广泛的表面表征，动力学和同位素标记研究实验将进行解释观察到的显着的选择性。此外，这些工具将被用来获得有用的见解Mn在激活CO和NO的作用，了解中间表面物种的性质，并将确定表面物种的反应机制的作用。拟议的研究在环境和能源方面具有独特的实际意义，这些领域对未来非常重要。预计拟议的工作将广泛影响科学知识库，教育和整个社会。压倒一切的驱动因素是制定更有效的环境过程，并开发新的技术概念，推进目前的国家的最先进的催化使用CO的教育的影响预计将是多方面的。通过为高中生开发创新的实践演示、海报展示和社区层面的展示参与，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，鼓励创新，激发研究生教育的兴趣。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。如果获得资助，它将为空气污染控制提供更经济的先进催化剂。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。