High-Octane Biogasoline

Gasoline made from biomass may be one step closer to the pump, thanks to a sequence of reactions that for the first time yields branched alkanes when starting from a biobased chemical feedstock. Short to medium-length branched alkanes are crucial components of gasoline because they allow the fuel to combust smoothly and predictably, a property measured by the octane rating. Current biofuel production methods mostly make linear alkanes, which don’t provide a sufficient octane rating for standard gasoline engines, although the longer alkanes produced are useful for diesel fuel or jet fuel. Mark Mascal and coworkers at the University of California, Davis, optimized two known catalytic reactions and developed a third to assemble a process (major products shown) that converts levulinic acid—a popular biofeedstock—to desirable branched C₇ to C₁₀ alkanes (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201308143). “Levulinic acid can be derived directly from raw biomass in about 80% yield,” Mascal explains, so “field-to-tank yields of cellulosic gasoline of greater than 60% are achievable by this approach.” The future of biogasoline still depends on competition from petroleum and the availability of biomass to produce levulinic acid.