Adipic acid is widely used in the production of nylon, plasticizers, polyurethane resins, adhesives, lubricants, etc. and hence the compound annual growth rate of adipic acid is expected to be 4.4% with a market size of over USD 7,000 million. At present adipic acid is commercially manufactured using petrochemical feedstock like benzene, hexane, hexene, hexanone, etc. using nitric acid as the catalyst. The research community is exploring newer methodologies to synthesize adipic acid and other industrially valuable chemicals using renewable feedstock one of them being biomass. There are mainly two routes of synthesizing adipic acid from biomass–chemocatalytic and biological. Within these routes, there are a variety of processes like deoxydehydrogenation (DODH), hydrodeoxygenation, direct synthesis via oxidation-hydrogenation that help convert biomass to adipic acid. With heterogeneous catalysis as a developing domain, researchers have developed a variety of catalysts like zeolites, silica-based catalysts, biological catalysts, deep utectic solvents as catalysts and a variety of other heterogeneous catalysts that convert that biomass containing cellulose, hemicellulose, lignin, other sugars to adipic acid efficiently. The paper reviews all the methodologies, catalysts for conversion and market demand of adipic acid.
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