SusChEM: Catalytic lignin degradation

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

The Chemical Catalysis program of the Division of Chemistry supports the research of Professor Corey Stephenson. Professor Stephenson is a faculty member at the University of Michigan. The goal of the project is to develop sustainable photocatalytic chemical methods for biomass degradation and repurposing. The total amount of biomass currently produced by the forestry and agricultural industries is estimated to be sufficient to replace petroleum as a carbon feedstock for fine chemicals. The Stephenson group is developing methods to degrade and convert lignin, the second most abundant biopolymer in the world, to valuable commodity chemicals. Lignin's high aromatic content is converted into useful feedstocks and complementing the aliphatic chemicals that can be derived from cellulose. This research focus is an integral component of Professor Stephenson's educational plans as a training opportunity for students in his laboratory. In addition, it provides hands-on experimental modules integrated into a series of outreach elements designed to engage high school students in the exciting opportunities in green chemistry and molecular sciences. Graduate and undergraduate trainees in the Stephenson group are exposed to a broad range of interdisciplinary topics, such as catalysis, photochemistry, renewable energy and flow chemistry. The focus is on using electron transfer-initiated transformations to promote chemoselective C-O and C-C bond cleavage reactions of lignin chemical linkages, processes for sustainable chemistry that are situated at the intersection of organometallic chemistry, photochemistry and materials science. These operationally simple, catalytic methods obviate the need for specialized photochemistry equipment, utilizing inexpensive and energy efficient LEDs for irradiation. The challenges of lignin degradation are addressed using a combination of oxidative and reductive visible light-mediated radical chemistry. The proposal consists of three specific aims: 1) development of new catalytic oxidation methods employing both photoredox catalysis and electron shuttling agents; 2) development of novel visible light-mediated reductive C-O and C-C cleavage methods; 3) implementation of the strategies developed in aims 1 and 2 toward the degradation of commercial lignin in continuous flow. The objectives advance the broader concept of sustainable chemistry without compromising reaction efficiency and chemoselectivity.