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对 MnOx/TiO2 表面 CO 活化的基本理解的研究计划。该研究重点关注 CO 不被氧化为 CO2 的反应的具体情况。非选择性），但它更适用于选择性化学转化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 催化剂对于用 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%，反应增强。我们的原位 FT-IR 研究表明，MnOx/TiO2 上的反应机理与之前报道的过度支持的反应机理不同。金属和钙钛矿基催化剂，由于不形成 -NCO 物质，其被广泛报道为中间体。2178 cm-1 A 处不存在明显的吸收带，证实了不形成 -NCO 物质。将进行合成、现代技术表征和动力学研究的平衡计划，以揭示所提出的催化剂的反应途径/机制，预计所提出的研究将为表面化学和反应过程中发生的反应途径提供基本的了解。在 Mn/TiO2 催化剂上，在高浓度氧气存在的情况下，在 150 至 350 °C 范围内，CO 的活化我们的研究将集中于 CO 与 NO 的反应，其中后者化合物充当催化剂。 Mn 导致在低温下观察到的选择性和活性增加以及对水的高耐受性的具体作用将得到彻底研究。此外，这些工具将用于获得关于 Mn 在活化 CO 和 NO 中的作用的有用见解，了解中间表面物种的性质，并确定表面物种对反应的作用。拟议的研究对环境和能源具有独特的实际意义，这两个领域对未来非常重要，预计将广泛影响科学知识基础、教育和整个社会。制定更有效的环境流程，并开发新技术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，预计对教育的影响将是多方面的。以及面向工业界和学术界的多学科研讨会，将吸引广泛的本科生参与该领域，以鼓励创新并激发对研究生教育的兴趣。少数民族和拟议的工作具有潜在的巨大社会经济影响。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，而且，在选择性转化二氧化碳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。