Co-production of monomers, including at least one bio-based monomer
Processes for the oxidation of carbohydrate dehydration products, such as furanics that can be oxidized to the bio-based monomer 2,5-furandicarboxylic acid (FDCA), are disclosed, according to which certain co-feeds, having been discovered to impart a beneficial reaction stabilizing effect, are oxidized together with the carbohydrate dehydration products. This can advantageously counteract, in whole or in part, detrimental effects of human impurities present in oxidation feed, with such impurities having been generated as byproducts of the upstream dehydrating step. An important co-feed is para-xylene that can be co-oxidized to form the petroleum-based monomer terephthalic acid (TPA), such that co-processing can beneficially yield two valuable monomers, while improving performance, particularly in terms of reaction stability, over comparable processes in which only the first monomer is produced. Related aspects involve opportunities for retrofitting existing monomer production facilities to enable co-processing of carbohydrate dehydration products that can lead to the above-noted advantages.
1 . A process for making a mixed monomer composition comprising 2,5-furan dicarboxylic acid (FDCA) and terephthalic acid (TPA), the process comprising:
co-feeding (i) FDCA-forming furanics and (ii) para-xylene to an oxidation reactor containing an oxidation catalyst and reactant oxygen, to provide the mixed monomer composition; wherein
Said oxidation catalyst comprises either or both of Co and Mn.
2 . The process of claim 1 , wherein the mixed monomer composition comprises an aldehyde derivative of FDCA and an aldehyde derivative of TPA, and the process further comprises selectively hydrogenating one or both of the aldehyde derivative of FDCA and the aldehyde derivative of TPA.
3 . The process of claim 2 , wherein said selectively hydrogenating one or both of the aldehyde derivative of FDCA and the aldehyde derivative of TPA occurs following a separation of the mixed monomer composition into an FDCA-enriched fraction and a TPA-enriched fraction.
4 . The process of claim 1 , wherein the mixed monomer composition comprises an aldehyde derivative of FDCA and an aldehyde derivative of TPA,
the process further comprises, in a step of esterifying one or both of the FDCA and TPA, producing one or both of an aldehyde derivative of an ester derivative of FDCA and an aldehyde derivative of an ester derivative of TPA, and
the process further comprises selectively hydrogenating one or both of the aldehyde derivative of the ester derivative of FDCA and the aldehyde derivative of the ester derivative of TPA.
5 . The process of claim 4 , wherein the process comprises esterifying both of the FDCA and TPA by reacting the mixed monomer composition with an esterifying agent, to provide an esterified mixed monomer composition comprising both the aldehyde derivative of the ester derivative of FDCA and the aldehyde derivative of the ester derivative of TPA.
6 . The process of claim 4 , wherein the
esterifying one or both of the FDCA and TPA occurs in a step of esterifying one or both of an FDCA-enriched fraction and a TPA-enriched fraction, by reaction with an esterifying agent, downstream of a separation of the mixed monomer composition into the FDCA-enriched fraction and the TPA-enriched fraction.
7 . The process of claim 1 , wherein the co-feeding comprises providing the FDCA-forming furanics and the para-xylene as separate feed streams to the oxidation reactor.
8 . The process of claim 1 , wherein the
co-feeding comprises combining the FDCA-forming furanics and the para-xylene into a combined feed stream and providing the combined feed stream to the oxidation reactor.
9 . The process of claim 1 , further comprising, prior to said co-feeding, dehydrating one or more carbohydrates in a solution comprising a lower carboxylic acid or a lower alcohol to obtain the FDCA-forming furanics in a crude dehydration product mixture, and supplying the FDCA-forming furanics directly to the oxidation reactor with the para-xylene in a separate feed stream or in a combined feed stream.
10 . The process of claim 9 , wherein the solution further comprises para-xylene.