RUI: CAS: Mapping Catalytic Sites on Alkali Promoted Anatase Titanium Dioxide (TiO2)

降低可再生燃料生产的成本是一个社会走向可持续经济的关键目标。能够加速化学反应而不被消耗的物质，通常被称为催化剂，将继续成为实现这一目标的关键因素。最近的进展提出了通过改变催化剂颗粒的形状来改进催化剂的新方法。适当的形状暴露出催化剂最有用的活性位点，同时最大限度地减少其他非活性位点或导致不良副反应和浪费的位点。在化学系化学催化项目的资助下，圣约翰费舍尔学院的Alexey Ignatchenko博士正在对催化剂形状进行微调，以最大限度地提高催化剂在工业化学品和生物燃料制备中的效率。催化生物燃料加工的成本节约为社会带来了明显的经济效益。这项研究为来自以本科生为主的大学的本科生提供了丰富的研究经验。学生们与橡树岭国家实验室的科学家互动，并使用纳米材料中心的专用仪器。该项目培养学生成为从事可再生能源研究的下一代科学家，这将确保我国的能源独立。许多可再生能源技术的成功取决于对反应性催化中心结构及其在原子尺度上的作用机制的详细了解。在化学催化项目的资助下，圣约翰费舍尔学院的Alexey Ignatchenko博士战略性地选择锐钛矿型TiO2晶体的最佳表面，并通过碱掺杂进一步微调其催化活性。他的研究小组研究了在锐钛矿型TiO2单晶的（001）或（101）表面分别添加钾和铯，以及在其中一种表面富集的纳米状颗粒上产生的催化中心。采用密度泛函理论（DFT）计算、漫反射红外傅立叶变换光谱（DRIFTS）、x射线光电子能谱（XPS）、电子显微镜分析、单个表面催化活性测试等理论和实验相结合的方法，了解酸性和碱性催化中心在脱羧酮化反应中的作用机理，这对生物燃料的升级具有重要意义。本研究对其它催化反应中碱促进剂和氧、- oh、- o -卫星碱中心的类型、数量或位置的合理修饰具有指导意义。参与该项目的学生将学习如何通过在分子水平上操纵催化剂结构和改进反应机制的关键步骤来控制催化过程的活性和选择性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Lowering the cost of renewable fuel production is a key goal for a society moving toward a sustainable economy. Substances that accelerate chemical reactions without themselves being consumed, commonly referred to as catalysts, will continue to be the key element towards achieving this goal. Recent advances suggest new ways of improving catalysts by modifying the shape of the catalyst particles. The proper shape exposes the catalyst’s most useful reactive sites while minimizing other sites that are either unreactive or that lead to undesirable side reactions and waste. With funds from the Chemical Catalysis Program in the Division of Chemistry, Dr. Alexey Ignatchenko of St. John Fisher College is fine-tuning catalyst shapes to maximize catalyst effectiveness for the preparation of industrial chemicals and biofuels. Cost savings in catalytic biofuel processing brings a clear economic benefit to society. The study provides enriching research experiences for undergraduate students from a predominantly undergraduate institution. The students interact with scientists at the Oak Ridge National Laboratory and use the specialized instruments housed at the Center for Nano Materials. The project prepares students to be the next generation of scientists engaged in renewable energy research that will ensure our country’s energy independence. The success of many renewable energy technologies depends on detailed knowledge about the structure of reactive catalytic centers and the mechanism of their action on the atomic scale. With funding from the Chemical Catalysis Program, Dr. Alexey Ignatchenko of St. John Fisher College is strategically selecting the best available surface of anatase TiO2 crystals and further fine-tuning its catalytic activity by alkali doping. His research group studies catalytic centers created by adding potassium and cesium separately to (001) or (101) surfaces of anatase TiO2 single crystals as well as on nano shaped particles enriched by one of the surfaces. A combination of theoretical and experimental methods, such as Density Functional Theory (DFT) computations, Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTS), X-Ray Photoelectron Spectroscopy (XPS), electron microscopy analysis, and catalytic activity testing of individual surfaces is applied to understand the role of acidic and basic catalytic centers in the reaction mechanism of the decarboxylative ketonization reaction, which is important for upgrading biofuels. This study is guiding research and development in rational modification of the type, amount, or location of the alkali promoters and the satellite basic centers made of oxygen, –OH, and –O– for many other catalytic reactions. The students involved in the project learn how to control the activity and selectivity of a catalytic process by manipulating catalyst structures at the molecular level and by refining critical steps of the reaction mechanism.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.