Conversion of Biomass-Derived Isoprene and Acrolein to Terephthalate Acid (TPA) and Hydrocarbon Fuels

The conversion of biomass to biofuels and value-added chemicals has attracted numerous attentions in terms of less dependence on fossil fuel and increasing concerns on environmental problems. Hydrocarbon fuels such as diesel and jet fuel (C₈-C₂₁) have an advantage because of compatibility with the current infrastructure and a higher energy density suitable for truck and jet engines. Terephthalic acid (TPA) is an indispensable monomer precursor for polyesters such as polyethylene terephthalate (PET), a thermoplastic polymer with a broad spectrum of applications, ranging from drink bottles to polyester fibers. Several routes have studied to produce either TPA or hydrocarbon fuels using sustainable chemical blocks (e.g. furfural) as starting materials. Herein, we reported new approaches for the synthesis of both TPA and hydrocarbon fuels (C₈ and C₁₆) using abundant biomass-derived chemicals isoprene and acrolein as the starting materials. TPA can be prepared by a simple route avoiding the p-xylene production including Diels-Alder, aromatization and oxidation with a total yield of 32%. Then, by sharing the same intermediate, C₈ hydrocarbon can be prepared by a hydrodeoxygenation reaction from the intermediate 4-methyl-cyclohex-3-enecarbaldehyde of Diels-Alder reaction with up to 57% total yield. The transition metal catalysts such as Pt/C, Pd/C, Fe/SiO₂ and Ni/SiO₂ were screened to optimize the product yield.  Furthermore, a long chain C₁₆ hydrocarbon was also synthesized by a sequence of Diels-Alder reaction, reductive coupling, and hydrodeoxygenation from isoprene and acrolein as well.