One-pot production of branched decalins as high-density jet fuel from monocyclic alkanes and alcohols

Branched decalins are promising jet fuel components with high density, high thermal stability and low freezing point, but its accessibility is limited by fossil resources. Here we report a novel H2SO4 catalytic one-pot synthesis process using cyclic alcohols (cyclohexanol, cyclopentanol) and branched cycloalkanes (methylcyclohexane, methylcyclopentane) that can be derived from lignocellulose and/or refineries as feedstock. The reaction occurs in a consecutive way of dehydration, alkylation, rearrangement and hydrogen transfer to produce branched decalins. The dehydration/oligomerization of alcohols also produces branched cycloalkanes but the carbon yield and selectivity are very low, and the presence of branched cycloalkanes significantly improves the reaction. The reaction goes smoothly at room temperature and continuous feeding of alcohols can further increase the yield. Under optimized reaction conditions, the carbon yield and branched decalins selectivity vary in range of 61-87%, dependent on the reactants used. The branched decalins show good fuel properties like density as high as 0.88 g/mL and freezing point as low as -110 degrees C, and can be produced in large scale. (C) 2018 Elsevier Ltd. All rights reserved.