Biomass-derived 1,4-dimethylcyclooctane (DMCO), a cyclic alkane, has the potential to serve as a low-carbon, high-performance jet fuel blendstock that may enable jet fuel made with 100% bio-based aviation fuels. Isoprene, the DMCO precursor, can be produced from dehydration of isoprenol, which is obtained by sugar fermentation. In this study, the effects of acid type and acid strength on isoprenol dehydration were investigated with a wide range of solid acid catalysts using alumina, supported phosphoric acid, phosphotungstic acids and organosulfonic acids. It was found that Brønsted acid site favors the dehydration, as high selectivity to isoprene (80-90%) was obtained using a wide range of Brønsted acid catalysts at reaction temperatures from 200 to 300℃. In contrast, Lewis acid site favored isoprenol cracking, as isobutene was the main production from alumina, a Lewis acidic catalyst. While the effect of Brønsted acid strength on isoprene selectivity was minimal, low catalyst acids strength slowed catalyst deactivation, as supported phosphoric acid with the lowest acid strength among the catalysts showed relatively slow deactivation. The findings provide an efficient strategy for isoprene production utilizing solid Brønsted acid catalysts.
