Current Approaches to Alkyl Levulinates via Efficient Valorization of Biomass Derivatives

Abstract

Biomass is a potential non-food, carbon-neutral, and abundant resource, which can be used as an alternative to fossil fuels during the sustainable preparation of various platform chemicals. Alkyl levulinates (ALs) have found widespread application as flavorings, plasticizing agents, and fuel additives, as well as synthetic precursors to various building blocks. Several processes have been investigated to transform biomass and its derivatives into ALs, which mainly include: (i) direct esterification of levulinic acid (LA) with alkyl alcohols and (ii) alcoholysis reactions of renewable biomass feedstocks and their derivatives, including furfuryl alcohol (FAL), chloromethyl furfural (CMF), and saccharides. This review focuses on illustrating the effects of the biomass pretreatment step, catalyst texture, possible mechanisms, acidities, and intermediates on the synthesis of ALs from sustainable resources covering a wide range of intermediates, including diethyl ether (DEE), 4,5,5-triethoxypentan-2-one (TEP), ethoxymethylfuran (EMF), ethyl-D-fructofuranoside (EDFF), and ethyl-D-glucopyranoside (EDGP).

Production of levulinic acid and alkyl levulinates: a process insight

“…165,167 The alcoholysis via acid catalysts represents a convenient and atomeconomic route to obtained value-added alkyl levulinates. 168 Besides sulfuric acid and other acids, 47,150 various homogeneous and heterogeneous catalysts have been investigated such as zeolites, 151,169 sulfonic acid ion-exchange resins, 151,170,171 organo-silica nanotubes, 172 oxides, 173 salts, 174 and porous aluminosilicate acid catalysts 135 (Table 6); generally operating at temperatures range between 110-140 °C and pressure up to 20 bar to avoid to operate below the boiling point of the reagents. 175 Even though mineral acids are still favored for their low cost and high availability, heterogeneous catalysts are gaining a foothold in the industry, avoiding corrosion effects, limiting downstream steps and ecotoxicity, all with the same efficiency.…”

Sulphonated Carbon Dots Synthesized Through a One‐Pot, Facile and Scalable Protocol Facilitates the Preparation of Renewable Precursors Using Glucose/Levulinic Acid

“…However, it exhibits a relatively lower cetane number than diesel. [36] A typical LA esterification reaction achieves a near-complete conversion under acidic conditions at 120 °C up to 2 h. [37] Heteropolyacid, [38] zeolites, [39] metal oxides, [40] sulphonic acid-functionalized materials [41] are the prominent solid-acid catalysts for the LA esterification. In a variety, in the present study, the sulphonic acid functionalized CDs was developed by using the cheap ptoluenesulphonic acid (PTSA) precursor by following a one-pot thermalization procedure.…”

An overview of the obtaining of biomass-derived gamma-valerolactone from levulinic acid or esters without H2 supply

“…Finally, to reach the levulinic acid, HMF is dehydrated, whereas FUR is first hydrogenated and then dehydrated. Considering hexoses, the conversion of fructose tends to be higher than that of glucose (Liu et al 2020). In particular, the fructofuranose gives a higher selectivity to HMF due to its high reactivity and the presence of a five-membered ring (Assary et al 2012).…”