Recent development of production technology of diesel- and jet-fuel-range hydrocarbons from inedible biomass

Key catalytic processes for the production of diesel-fuel- and jet-fuel-range branched or cyclic alkanes from lignocellulose and microalgal oil are reviewed, in particular the processes for the constructing the carbon framework. Furfural, 5-hydroxymethylfurfural (HMF) and 2-methylfuran are the most fundamental building blocks (platform chemicals) in the synthesis of long chain alkanes from lignocellulose. Aldol condensation and alkylation of furan ring are key reactions to elongate the carbon chain. Hydrodeoxygenation follows the carbon chain elongation, giving final alkane product. Effective hydrodeoxygenation catalysts include Pd/NbOPO₄, Ir-ReO_x/SiO₂ and Ni/zeolites. Pd/NbOPO₄ catalyst is effective to convert furanic precursor with oxygen-containing chains. Ir-ReO_x/SiO₂ catalyst is attractive in view of the high activity (low reaction temperature), and Ni/zeolites are attractive in view of the catalyst cost. Lignin or raw lignocellulose can be converted to mixture of alkanes including diesel-fuel- and jet-fuel-range ones using catalytic cracking, alkylation and hydrogenation. Microalgal large hydrocarbons can be converted to smaller alkanes with retention of branches in the carbon chain by Ru/CeO₂-catalyzed C–C hydrogenolysis.