SusChEM: Single Molecule Studies of Aldol Condensation on Heterogeneous Catalysts

将可再生生物质资源转化为燃料提供了一种在不依赖化石燃料的情况下可持续地满足社会日益增长的能源需求的方法。然而，从生物质中最容易提取的化合物与从加工石油或页岩中获得的常规碳氢化合物大不相同。一个主要的区别是，大多数生物质衍生的化合物比碳氢化合物燃料小，需要催化反应才能从原始化合物中生成更大的分子。在这些反应中，催化剂是由化学物质组成的固体膜，这些化学物质有助于提高反应的效率，但本身不会在反应中消耗。Drs。约翰和希金斯正在研究一种这样的反应，醛醇缩合反应，以了解哪种催化性质最适合这项任务。为了实现这一目标，他们在催化剂膜上进行了发光反应，并沿着膜表面形成了催化特性梯度。观察薄膜的哪些部分发出最亮的光，可以提供最活跃的催化位点类型的信息，并允许团队设计改进的催化剂。研究成果正以几种方式传播，包括通过在科学会议上的报告和同行评议的出版物。Hohn博士还将研究成果纳入到K-12学生的拓展活动中，而Higgins博士则将研究成果引入到显微镜教科书和研究生水平的化学课程中。在化学部化学催化项目的资助下，dr。堪萨斯州立大学的Hohn和Higgins正在对醛醇缩合反应的催化性质有一个基本的了解。他们正在应用单分子方法同时测量薄膜上酸/碱性质和醛醇缩合活性，并结合酸/碱位点密度的梯度。通过这些测量，他们将醛醇缩合的催化活性与酸/碱位点的强度和密度联系起来。该团队应用表面表征方法，包括x射线光电子能谱（XPS）和拉曼映射研究，来增强单分子表征研究。此外，博士。Hohn和Higgins通过制备在分子水平上酸和碱位点混合的薄膜以及酸和碱位点被宏观距离分开的薄膜，将醛缩反应的催化活性与酸碱位点接近联系起来。除了定期在同行评审文献和会议上发表结果外，Hohn博士还将研究的各个方面纳入堪萨斯州立大学的外展项目活动中，以加强从代表性不足的群体中招募学生进入科学和工程领域，而Higgins博士则将精选的结果引入研究生课程和化学显微镜教科书中。

Converting renewable biomass resources to fuels provides a way to meet society's growing energy demands sustainably without reliance on fossil fuels. However, the compounds most easily extracted from biomass are quite different from conventional hydrocarbons obtained from processing petroleum or shale. One major difference is that most biomass-derived compounds are smaller than hydrocarbon fuels, necessitating catalytic reactions to build larger molecules from the original compounds. In these reactions, the catalyst is a solid film comprising chemicals that aid the efficiency of the reaction, but are not themselves consumed in the reaction. Drs. Hohn and Higgins are studying one such reaction, aldol condensation, to understand what catalytic properties are best suited to this task. To accomplish this, they follow a light-emitting reaction occurring on a catalyst film that they create with a gradient of catalytic properties along the film surface. Observing which parts of the film emit the brightest light provides information on the types of catalytic sites that are most active and allows the team to design improved catalysts. Research results are being disseminated in several ways, including through presentations at scientific conferences and peer reviewed publications. Dr. Hohn is also incorporating research results into outreach activities for K-12 students, while Dr. Higgins is introducing research results into a textbook on microscopy and into a graduate-level chemistry class.With funding from the Chemical Catalysis Program of the Chemistry Division, Drs. Hohn and Higgins of Kansas State University are developing a fundamental understanding of the catalytic properties responsible for activity in aldol condensation. They are applying single molecule methods to simultaneously measure acid/base properties and aldol condensation activity on thin films incorporating gradients in acid/base site densities. With these measurements, they are correlating catalytic activity in aldol condensation with the strengths and densities of the acid/base sites. The team applies surface characterization methods, including x-ray photoelectron spectroscopy (XPS) and Raman mapping studies, to augment the single molecule characterization studies. In addition, Drs. Hohn and Higgins correlate catalytic activity in aldol condensation with acid/base site proximity by preparing films with acid and base sites mixed at the molecular level and films where acid and base sites are separated by macroscopic distances. Along with regular publication of the results in the peer reviewed literature and presentation at conferences, Dr. Hohn is incorporates aspects of the research into activities for outreach programs at Kansas State University to enhance the recruitment of students from under-represented groups into science and engineering, while Dr. Higgins is introducing selected results into a graduate-level course and a textbook on chemical microscopy.