CAREER: SusChEM : Electrochemically Driven Deoxydehydration of Polyols

化学原料分子，如乙烯和丁烯，用于生产各种消费品，其高效和经济的生产对健康的经济至关重要。目前，这些原料是从原油等不可再生资源中提炼出来的。为了确保这些化学品的国内生产和可再生来源，可以使用催化反应将植物来源的生物质材料转化为原料和其他燃料。然而，目前生产这些原料的技术也会产生大量的废物，必须从所需的材料中分离出来。该项目开发电催化方法，利用电力和化学物质加速反应，但在过程中本身不会被消耗，以水作为唯一的副产品，将模型生物质有效地转化为原料。这项研究的广泛影响直接关系到可持续化学的发展，改善了工业重要化学品的可再生生产过程。这项工作还对培养一支成熟的劳动力队伍产生了更广泛的影响，因为它使研究生、本科生和博士后能够学习现代化学技术和可持续化学生产科学。研究工作与本科学生的“研究训练营”相结合，教授他们化学合成和表征的基础知识。这个“训练营”的参与者正在开发一个“连接库”，用于将催化剂固定在电极表面上。由“训练营”的本科生参与者开发的固定化策略解决了将电化学过程扩大到工业实际水平的关键问题。美国国家科学基金会化学部的化学催化项目资助阿肯色大学的Stefan Kilyanek博士，研究新开发的地球丰度-金属-氧催化剂的质子耦合电子转移（PCET）行为，用于多元醇的脱氧脱水（DODH），用于生产烯烃和二烯。通过PCET电化学还原金属-氧DODH催化剂是一种很有吸引力的策略，可以在不使用仲醇等牺牲还原剂和芳基膦等氧受体的情况下实现催化剂的转换。经PCET还原后，金属-氧催化剂形成与DODH催化循环中催化活性中间体相关的配合物。密度泛函理论计算通过探索空间和电子环境对关键反应步骤的热化学的影响来指导催化剂设计。在各种配体环境下，对含二氧钼和二氧钨的催化剂进行了研究。采用循环伏安法等电化学技术研究了PCET的催化行为，探讨了催化剂还原的机理。这项研究的广泛影响直接关系到可持续化学的发展，改善了工业重要化学原料的可再生生产过程。这项工作还对培养一支成熟的劳动力队伍产生了更广泛的影响，因为它使研究生、本科生和博士后能够学习现代化学技术和可持续化学生产科学。研究工作与本科学生的“研究训练营”相结合，教授他们化学合成和表征的基础知识。

Chemical feedstock molecules, such as ethylene and butylene, are used to a produce a wide range of consumer goods, and their efficient and economical production is crucial to a healthy economy. Currently, these feedstocks are refined from non-renewable resources such as crude oil. In order to secure a domestically-produced and renewable source of these chemicals, catalytic reactions can be used to convert plant-derived biomass material into feedstocks and other fuels. However, current technologies that produce these feedstocks also generate significant amounts of waste product that must be separated from the desirable materials. This project develops electrocatalytic methods, using electricity and chemicals that accelerate the reaction but are not themselves consumed in the process, to convert model biomass into feedstocks efficiently with water as the only byproduct. Broader impacts of the research are directly related to sustainable chemistry in the development of improved processes for the renewable production of industrially-important chemicals. This work also has broader impacts in developing a sophisticated workforce since it allows graduate students, undergraduate students and postdoctoral fellows to learn modern techniques in chemistry and the science of sustainable chemical production. The research work is integrated with a "research boot-camp" for undergraduate students that teaches them the fundamentals of chemical synthesis and characterization. The participants in this "boot-camp" are developing a "linker library"for the immobilization of catalysts onto electrode surfaces. The immobilization strategies developed by the undergraduate participants in the "boot-camp" address issues critical to the scale-up of the electrochemical process to an industrially-practical level. With this award, the Chemical Catalysis Program of the Chemistry Division of the National Science Foundation funds Dr. Stefan Kilyanek of the University of Arkansas to study the proton-coupled electron transfer (PCET) behavior of newly developed earth-abundant-metal-oxo catalysts for the deoxydehydration (DODH) of polyols for the production of alkenes and dienes. Electrochemical reduction of metal-oxo DODH catalysts via PCET is an attractive strategy for achieving catalyst turnover without using sacrificial reductants such as secondary alcohols and oxo-acceptors like aryl phosphines. Upon reduction via PCET, metal-oxo catalysts form complexes that are relevant to catalytically active intermediates in the DODH catalytic cycle. Density Functional Theory calculations are used to guide catalyst design by exploring the impact of steric and electronic environments on the thermochemistry of critical reaction steps. Catalysts containing the dioxo-molybdenum and dioxo-tungsten moieties in a variety of ligand environments are being studied. The catalytic PCET behavior is studied by cyclic voltammetry and other electrochemical techniques to probe the mechanism of catalyst reduction. Broader impacts of the research are directly related to sustainable chemistry in the development of improved processes for the renewable production of industrially-important chemical feedstocks. This work also has broader impacts in developing a sophisticated workforce since it allows graduate students, undergraduate students and postdoctoral fellows to learn modern techniques in chemistry and the science of sustainable chemical production. The research work is integrated with a "research boot-camp" for undergraduate students that teaches them the fundamentals of chemical synthesis and characterization.