Renewable Isoprene By Sequential Hydrogenation of Itaconic Acid and Dehydra-Decyclization of 3-Methyl-Tetrahydrofuran

2018 Spring Symposium

Omar Abdelrahman, Post-Doc, Paul Dauenhauer Group, Department of Chemical Engineering & Material Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, MN 55455

Abstract – The catalytic conversion of biomass-derived feedstocks to value added chemicals is an important challenge to alleviate the dependence on petroleum-based resources. To accomplish this, the inherently high oxygen content of biomass compounds, such as that of lignocellulosic biomass, requires significant reduction via hydrodeoxygenation strategies. The unsaturated carboxylic acid itaconic acid (IA) can be produced from biomass via fermentation pathways, for example. A pathway of interest is the conversion of IA to isoprene, facilitating the renewable production of an industrially relevant diolefin. IA can be successively hydrogenated to yield 3-methyl tetrahydrofuran (3-MTHF), in a one-pot cascade reaction, where a Pd-Re bimetallic catalyst results in an 80% yield to 3-MTHF. The 3-MTHF can then be converted to isoprene, and other pentadienes, through an acid catalyzed vapor-phase dehydra-decyclization. Multiple solid acid catalysts, including aluminosilicates, metal oxides and phosphorous modified zeolites, were screened for the dehydra-decyclization step. A new class of catalytic materials, all silicon
phosphorous containing zeolites, were found to be the most selective (70% isoprene and 20% pentadienes), where the major side reaction involved is a retro-prins condensation of 3-MTHF to butane and formaldehyde. Through kinetic studies, an investigation into the effect of Brønsted acid strength, pore size and operating conditions on the selectivity to isoprene are discussed. The prospect of applying this dehydra-decyclization strategy to other saturated cyclic ethers will also be discussed, which enables the production of other diolefin molecules of interest such as butadiene and linear pentadienes.

[1] Abdelrahman, O. A.; Park, D. S.; Vinter, K. P.; Spanjers, C. S.; Ren, L.; Cho, H. J.; Zhang, K.; Fan, W.; Tsapatsis, M.; Dauenhauer, P. J. ACS Catal. 2017, 7, 1428-1431.