Production of liquid hydrocarbon transportation fuels by oligomerization of biomass-derived C-9 alkenes

A process is described to produce renewable liquid fuels, similar to existing petroleum-derived transportation fuels, through the oligomerization over solid acid catalysts of C-9-alkenes derived from gamma-valerolactone (GVL). Larger, non-terminal alkenes are shown to be less reactive than short chain alpha-alkenes for oligomerization over solid acid sites, and Amberlyst-70 has been identified to be an active and stable catalyst with sufficient acidity to couple C-9-alkenes. The inhibiting effect of water on alkene oligomerization can be minimized, because C-9 alkenes derived from aqueous solutions of GVL separate spontaneously from water. The effect of other impurities arising from the cascade process for production of C-9 alkenes from GVL, such as 5-nonanone and 5-nonanol, has been studied. Ketones are shown to be inert, while alcohols readily dehydrate on acid sites, producing an equivalent of water, which inhibits the rate of oligomerization. Small amounts of 5-nonanol present with C-9-alkenes (< 1%) have a promotional effect, due to swelling of the catalyst by polar molecules; however, large amounts of 5-nonanol lead to inhibition of oligomerization. Other more reactive alkenes present in C-9-alkenes produced from GVL, such as hexene and heptene isomers, compete for acid sites with the nonene feed. These smaller, more reactive alkenes are readily coupled at high conversion. Accordingly, with this process approximately 50 kg of liquid hydrocarbons can be produced from 100 kg of GVL retaining more than 90% of its energy content.