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Conventional biorefinery processes are complex, engineered and energy-intensive, where biomass fractionation, a key functional step for the production of biomass-derived chemical substances, demands industrial organic solvents and harsh, environmentally harmful reaction conditions. There is a timely, clear and unmet economic need for a systematic, robust and affordable conversion method technology to become greener, sustainable and cost-effective. In this perspective, deep eutectic solvents (DESs) have been envisaged as the most advanced novel polar liquids that are entirely made of natural, molecular compounds that are capable of an association via hydrogen bonding interactions. DES has quickly emerged in various application functions thanks to a formulations’ simple preparation. These molecules themselves are biobased, renewable, biodegradable and eco-friendly. The present experimental review is providing the state of the art topical overview of trends regarding the employment of DESs in investigated biorefinery-related techniques. This review covers DESs for lignocellulosic component isolation, applications as (co)catalysts and their functionality range in biocatalysis. Furthermore, a special section of the DESs recyclability is included. For DESs to unlock numerous new (reactive) possibilities in future biorefineries, the critical estimation of its complexity in the reaction, separation, or fractionation medium should be addressed more in future studies.

As one of the most demanded dicarboxylic acids, adipic acid can be directly produced from renewable sources. Hexoses from (hemi)cellulose are oxidized to aldaric acids and subsequently catalytically dehydroxylated. Hitherto performed homogeneously, we present the first heterogeneous catalytic process for converting an aldaric acid into muconic and adipic acid. The contribution of leached Re from the solid prereduced catalyst was also investigated with hot-filtration test and found to be inactive for dehydroxylation. Corrosive or hazardous (HBr/H 2) reagents are avoided and simple alcohols and solid Re/C catalysts in an inert atmosphere are used. At 120 8C, the carboxylic groups are protected by esterification, which prevents lactonization in the absence of water or acidic sites. Dehydroxylation and partial hydrogenation yield monohexenoates (93 %). For complete hydrogenation to adipate, a 16 % higher activation barrier necessitates higher temperatures.

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Ruthenium catalyzed and magnetically heated hydrogenation of furfural in a slurry-type reactor is demonstrated in this work. We have developed a catalyst composed of magnetic-nanoparticles-containing alumina carrying Ru nanoparticles on...

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Hydrotreatment of mucic acid (also known as galactaric acid, an glucaric acid enantiomer), one of the most promising bio-based platform chemicals, was systematically investigated in aqueous media over alumina, silica, or carbon-supported transition (nickel and nickel-molybdenum) or noble (platinum, ruthenium and rhodium) metals. Mucic acid was only converted into mucic-1,4-lactone under non-catalytic reaction conditions in N2 atmosphere, while the 5 MPa gaseous H2 addition triggers hydrogenation in the bulk phase, resulting in formation of galacturonic and galactonic acid. However, dehydroxylation, hydrogenation, decarbonylation, decarboxylation, and cyclization occurred during catalytic hydrotreatment, forming various partially and completely deoxygenated products with a chain length of 3–6 C atoms. Characterization results of tested catalysts were correlated with their activity and selectivity. Insufficient pore diameter of microporous supports completely hindered the mass transfer of reactants to the active sites, resulting in negligible conversion of mucic acid. A comprehensive reaction pathway network was proposed and several industrially interesting compounds were formed, including levulinic acid, furoic acid, and adipic acid. However, selectivity towards adipic acid, a bio-based nylon 6,6 precursor, was low (up to 5 mol%) in aqueous media and elevated temperatures.

As one of the most demanded dicarboxylic acids, adipic acid can be directly produced from renewable sources. Hexoses from (hemi)cellulose are oxidized to aldaric acids and subsequently catalytically dehydroxylated. Hitherto performed homogeneously,w ep resent the first heterogeneous catalytic process for converting an aldaric acid into muconic and adipic acid. The contribution of leached Re from the solid prereduced catalyst was also investigated with hot-filtration test and found to be inactive for dehydroxylation. Corrosive or hazardous (HBr/H 2 )reagents are avoided and simple alcohols and solid Re/C catalysts in an inert atmosphere are used. At 120 8 8C, thec arboxylic groups are protected by esterification, which prevents lactonization in the absence of water or acidic sites.Dehydroxylation and partial hydrogenation yield monohexenoates (93 %). Forc omplete hydrogenation to adipate, a1 6% higher activation barrier necessitates higher temperatures.