Valeric Biofuels from Biomass-Derived γ-Valerolactone: A Critical Overview of Production Processes

This review analyzes critically the production of valeric biofuels from γ-valerolactone, a relevant biomass-derived platform molecule. Initially, the main properties of valeric esters as fuels for spark- and compression-ignition engines are summarized. Then, catalytic routes to valeric esters from γ-valerolactone are meticulously analyzed, describing the acid- and metal-catalyzed reactions taking part in the tandem catalysis. Only works focused on the production of the valeric biofuels were considered, excluding the cases where these esters were observed in minor amounts or as byproducts. The role of the appropriate selection of the support, catalytic species, catalyst preparation and experimental conditions on the valeric ester productivity are thoroughly commented. Finally, some concluding remarks and perspectives are given, mentioning the areas where additional efforts must be done in order to turn the dream of a massive and renewable valeric biofuel production into a reality.

Production of pentyl valerate from γ-valerolactone, pentanol and H2 using Pd and Rh-based bifunctional catalysts

Easily prepared SiO2–Al2O3-supported Rh and Pd-based catalysts exhibit high activity and selectivity in the pentyl valerate production in liquid phase from γ-valerolactone, pentanol and H2, reaching the highest reported productivity.

Valeric Biofuel Production from γ-Valerolactone over Bifunctional Catalysts with Moderate Noble-Metal Loading

SiO2 -Al2 O3 -supported Ru, Ir and Pt-based catalysts with moderate metal loading (1 %) were tested for the first time in the production of pentyl valerate (PV) in liquid phase from γ-valerolactone, pentanol (in excess) and H2 . The acidity of these bifunctional catalysts, plays a key role in the one-pot process comprising two consecutive acid-catalyzed reactions and a metal-catalyzed one. Metal dispersion also shown to be relevant for the conversion of the pentyl pentenoate intermediate into PV by hydrogenation over the metal sites. Pt/SA catalyst with the highest surface acidity and metal dispersion reached optimal GVL conversion with a PV yield of 90.0 % after 10 h, exhibiting a PV productivity of 300 mmol/gM .h, i. e. a value between three and four times higher than the best result reported until now (91.8 mmol/gM .h). These findings highlight the potential that noble metal-based catalyst with moderate metal loading have in the valorization of biomass-derived platform molecules such as γ-valerolactone.