Abstract
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.
Highlights
A huge amount of interest is devoted to a search of new sources and processes for the production of industrially important chemicals, especially monomers, which can substitute petrol-based precursors.To avoid competition between food and chemical or fuel production, only non-edible biomass should be utilized in the chemical industry
The same trend in the size distribution was observed for pore volume—the highest value was determined for Pt/C and the lowest for the Pt/γ-Al2 O3, which was comparable to the NiMo/γ-Al2 O3
The results show that commercial catalysts contain well dispersed metal clusters below 5 nm in size
Summary
A huge amount of interest is devoted to a search of new sources and processes for the production of industrially important chemicals, especially monomers, which can substitute petrol-based precursors. To avoid competition between food and chemical or fuel production, only non-edible biomass should be utilized in the chemical industry. The missed opportunities for converting biomass into chemicals lie in agricultural wastes, wood residues, and other similar lignocellulosic materials [1,2,3]. Lignocellulosic biomass is composed of three main polymer structures—lignin, cellulose, and hemicellulose. Each of them presents its own system of potential sources of chemicals [4]. Glucose as a cellulose monomer has a high potential for biopolymer production. Oxidation of a glucose at both terminal C-atoms yields a group of dicarboxylic sugar acids, named aldaric acids (saccharic acids), poorly soluble in polar and nonpolar solvents [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
