Oxidative pretreatment of carbohydrate dehydration products comprising humins

Abstract

Processes for oxidative pretreatment of carbohydrate dehydration products are disclosed, which relate to the discovery that functional groups of humins, such as those that result in, or lead to, color formation (e.g., aldehyde groups and/or groups having conjugated double bonds) may be more readily converted by oxidation (in some cases 'bleached') than FDCA-forming furanics. This selective oxidation of humins may use milder oxidation conditions and/or a different reaction system, compared to respective conditions and systems used for oxidation of furan ring-containing compounds. Oxidative pretreatment can beneficially promote the selective oxidation of humin functional groups over FDCA-forming furanics, with the overall result of modifying humins in a manner that can provide a number of improvements. These may particularly reside in the further processing of the obtained, pretreated dehydration product, such as in the overall manufacture of bio-based poly(alkylene furan dicarboxylate) copolymers, a prominent example of these being poly(ethylene furan dicarboxylate), or PEF.