SusChEM: Surface Active Site Design for Selective Deoxygenation

许多化学过程需要在不影响其他键的情况下在化合物中形成或断开碳-氧键的能力。生物质转化为燃料和化学品需要碳氧键解离(或“脱氧”)反应，以改善生物质衍生化合物与现有炼油基础设施的兼容性。不幸的是，对脱氧有效的催化剂通常也会催化其他不受欢迎的反应，从而导致碳的损失。因此，设计专门从原料中去除氧气的固体材料的能力是现代催化研究的目标。在这个项目中，科罗拉多大学博尔德分校的J.Will Medlin博士正在研究如何调整催化剂表面含氧反应物之间的相互作用，以实现从原料中特定地脱除氧气。梅德林博士还在研究催化剂纳米结构在促进除氧反应方面发挥的作用，而不是那些去除碳的反应。该项目将科学推广和培训纳入研究计划。这些外展活动包括为本科生提供暑期研究机会，以及扩大一年一度的化学和化学工程“野外日”活动，该活动的重点是为中学生提供动手科学实验。在化学系化学催化项目的资助下，科罗拉多大学博尔德大学的J.Will Medlin博士正在研究醇在金属表面上的脱氧反应机理。选择性地激活碳-氧键在许多应用中都很重要，包括将生物质衍生化合物转化为燃料和化学品。由于碳-碳键的断裂通常会导致碳损失和效率降低，因此确定对碳-氧键活化具有选择性的催化剂尤为重要。虽然某些金属表面对脱氧具有异常的活性和选择性，但表面性质和脱氧性能之间的关系尚不清楚，这阻碍了设计改进催化剂的努力。在这个项目中，梅德林博士采用了使用模型表面的实验研究、密度泛函理论计算和负载型催化剂实验相结合的方法，系统地研究了以前与高脱氧选择性相关的因素。在本项目中，利用同位素示踪研究系统地研究了脱氧过程中关键的氢转移步骤的机理。对各种钯表面的脱氧选择性和动力学进行了测量，以确定与有效脱氧相关的几何结构。该项目的目标是确定简单的催化剂描述符，以便为高效催化剂的设计提供信息。该项目通过对不同层次的学生进行研究性培训，以及由梅德林博士的团队组织的一年一度的中学生“田野日”活动，强调STEM教育。

Many chemical processes require the ability to make or break carbon-oxygen bonds in a compound without affecting other bonds. The conversion of biomass to fuels and chemicals requires carbon-oxygen bond dissociation (or "deoxygenation") reactions to improve the compatibility of biomass-derived compounds with the existing refining infrastructure. Unfortunately, catalysts that are effective for deoxygenation also often catalyze other, undesired reactions that lead to the loss of carbon. The ability to design solid materials that specifically remove oxygen from a feedstock is thus a goal of modern catalysis research. In this project, Dr. J. Will Medlin of the University of Colorado Boulder is investigating how interactions between oxygen-containing reactants on catalyst surfaces can be tuned to allow for specific removal of oxygen from a feedstock. Dr. Medlin is also investigating the role that catalyst nanostructure plays in favoring oxygen removal reactions over those that remove carbon. The project integrates scientific outreach and training within the research program. These outreach activities include summer research opportunities for undergraduate students, as well as expansion of an annual chemistry and chemical engineering "Field Day" activity that is focused on hands-on science experiments for middle school students. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. J. Will Medlin of the University of Colorado Boulder is developing an understanding of the mechanism for deoxygenation reactions of alcohols on metal surfaces. Selective activation of carbon-oxygen bonds is important in many applications, including the conversion of biomass-derived compounds to fuels and chemicals. It is especially important to identify catalysts that are selective for carbon-oxygen bond activation, since cleavage of carbon-carbon bonds generally results in carbon loss and reduced efficiency. Although certain metal surfaces have been identified as being unusually active and selective for deoxygenation, the relationship between surface properties and deoxygenation performance is not well understood, hampering efforts to design improved catalysts. In this project, Dr. Medlin is employing a combination of experimental studies using model surfaces, density functional theory calculations, and experiments with supported catalysts to systematically investigate factors that have previously been associated with high deoxygenation selectivity. In this project, isotope tracing studies are employed to systematically investigate the mechanism for the critical hydrogen transfer step during deoxygenation. Deoxygenation selectivity and kinetics are measured for a variety of palladium surfaces to identify the geometric structures associated with efficient deoxygenation. The goal of this project is to identify simple catalyst descriptors that can inform design of efficient catalysts. This project emphasizes STEM education through the research training of students across multiple levels, as well as through an annual "Field Day" activity for middle school students organized by Dr. Medlin's group.