Production and catalytic transformation of levulinic acid: A platform for speciality chemicals and fuels

Lignocellulosic biomass is a renewable and abundant source that can be used as a replacement for fossil resources in the sustainable production of speciality chemicals and transportation fuels. Over the last several decades, it has been demonstrated that one of the most effective methodology is to converse the high concentration of oxygen functionalized biomass monomers (e.g., cellulose, hemicelluloses) through de-functionalization into levulinic acid (LA) that has low oxygen content, followed by catalytic transformation of LA into fuels and valuable chemicals. This strategy currently seems to be the logical and promising alternative for sustainable development in the context of economic and environmental considerations. Besides, LA has been identified as one of the most promising platform chemicals for the sustainable production of fuels and commodity chemicals. This review is an up-to-date progress of literatures available on the subject of speciality chemicals and fuels derived from biomass through LA platform. The mechanism and current technologies for the production of LA are reviewed and compared. The potential theoretical calculation methods such as ab initio methods and density functional theories to predict the reaction pathway was also commented. The various transformation methods started from LA to speciality chemicals and fuels are critically reviewed. Among the various products, γ-valerolactone, 2-methyltetrahydrofuran and levuinate esters have been identified as promising fuels. The commercial diphenolic acid and delta-aminolevulinic acid have been widely utilized in many areas. The potential applications as well as fuel properties of these products are also discussed.