New Frontiers in the Catalytic Synthesis of Levulinic Acid: From Sugars to Raw and Waste Biomass as Starting Feedstock

Abstract

Levulinic acid (LA) is one of the top bio-based platform molecules that can be converted into many valuable chemicals. It can be produced by acid catalysis from renewable resources, such as sugars, lignocellulosic biomass and waste materials, attractive candidates due to their abundance and environmentally benign nature. The LA transition from niche product to mass-produced chemical, however, requires its production from sustainable biomass feedstocks at low costs, adopting environment-friendly techniques. This review is an up-to-date discussion of the literature on the several catalytic systems that have been developed to produce LA from the different substrates. Special attention has been paid to the recent advancements on starting materials, moving from simple sugars to raw and waste biomasses. This aspect is of paramount importance from a sustainability point of view, transforming wastes needing to be disposed into starting materials for value-added products. This review also discusses the strategies to exploit the solid residues always obtained in the LA production processes, in order to attain a circular economy approach.

Recycling of Sulfuric Acid in the Valorization of Biomass Residues

“…2) [9]. Accordingly, several attempts were made to produce 5-HMF and/or LA from simple sugar molecules such as D-fructose or D-glucose in the presence of well-designed catalyst species i.e.…”

Upgrading Lignocellulosic Biomasses: Hydrogenolysis of Platform Derived Molecules Promoted by Heterogeneous Pd-Fe Catalysts

“…The first step for cellulose valorization is based on its depolymerisation into oligomers and glucose followed by catalytic reactions (hydrogenation, oxidations, esterification, etc.) for the manufacture of a pool of chemicals such as C6-C2 polyols, levulinic acid, hydroxymethylfurfural (HMF), among others ( [25][26][27][28][29] and "references within"). Polyols, owing to their peculiar chemical properties, could represent an important resource for production of several building-block chemicals.…”

Catalytic Transfer Hydrogenolysis as an Effective Tool for the Reductive Upgrading of Cellulose, Hemicellulose, Lignin, and Their Derived Molecules

“…LA has attracted much attention because it is one of the top biomass derived platform molecules that can be made by the transformation of the lignocellulosic biomass followed by hydration and dehydration of hexose sugars [96,97]. The different chemical products that can be derived from LA are collected in Figure 3.…”