CAREER: SusChEM : Electrochemically Driven Deoxydehydration of Polyols

University Of Arkansas, Fayetteville AR

Investigators

Abstract

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.