Catalytic upgrading of muconates for renewable chemical applications

Abstract

Due to growing awareness of environmental impacts and the economic volatility of petroleum, there has been a drastic increase in research towards biomass-derived, sustainable alternatives to petroleum-based processes and products. Notably, commodity chemicals for production of commercial products are exclusively manufactured using feedstocks derived from crude oil refining and currently account for over one third of the worldwide industrial energy demand. As the market demand for petrochemicals are only forecasted to grow, development and advancement of renewable chemical processes is timely. Lignocellulosic biomass presents as a promising alternative source for these aromatic monomers due to the diverse structure and inherently high oxygen content within its components: lignin, cellulose, and hemicellulose. However, significant research is needed in order to realize the use of lignocellulosic biomass as a platform for such chemical products and to push these renewable chemical processes toward industrial and commercial relevance. This work focuses on the catalytic conversions of cis,cis-muconic acid (cis,cis-2,4-hexadienedioic acid), a polyunsaturated C6 dicarboxylic acid that can be microbiologically produced from lignocellulosic biomass streams. The state of catalysis for Diels-Alder reactions involved in upgrading schemes of muconic acid and other biomass-derived products to drop-in and functional alternative commodity monomers is reviewed and evaluated, followed by concentrated studies into the iodine-catalyzed isomerization of cis,cis¬-dimethyl muconate to the Diels-Alder active isomer, trans,trans-dimethyl muconate. Finally, an investigation into the use of atomic layer deposition to enhance the leaching resistance and thermal stability of supported platinum group metal catalysts during condensed phase hydrogenation of muconic acid to adipic acid is presented.