Purifying crude furan 2,5-dicarboxylic acid by hydrogenation
A process for purifying a crude furan 2,5-dicarboxylic acid composition (cFDCA) by hydrogenation of a FDCA composition dissolved in a hydrogenation solvent such as water, and hydrogenating under mild conditions, such as at a temperature within a range of 130° C. to 225° C. by contacting the solvated FDCA composition with hydrogen in the presence of a hydrogenation catalyst under a hydrogen partial pressure within a range of 10 psi to 900 psi. A product FDCA composition is produced having a low amount of tetrahydrofuran dicarboxylic acid, a low b*, and a low amount of 5-formyl furan-2-carboxylic acid (FFCA).
1. A furan 2,5-dicarboxylic acid composition comprising:
a) solids, wherein at least 98 wt. % of the solids are furan-2,5-dicarboxylic acid (FDCA), based on the weight of the solids;
b) a b* value of less than 4;
c) 5-formyl furan-2-carboxylic acid (FFCA) in an amount of less than 500 ppm; and
d) tetrahydrofuran dicarboxylic acid (THFDCA) present in an amount ranging from 0 to no more than 0.5 wt. %;
in each case based on the weight of the solids.
2. The composition of claim 1 , comprising:
a) at least 98 wt. % of solids;
b) a b* value of less than 3;
c) FFCA in an amount of less than 100 ppm; and
d) THFDCA in an amount of less than 100 ppm;
in each case based on the weight of the solids.
3. The composition of claim 2 , which has a b* value of not more than 1.
4. The composition of claim 1 , comprising:
a) 99 wt. % of solids, wherein at least 99 wt. % of the solids is FDCA;
b) a b* value of not more than 1;
c) FFCA in an amount of less than 50 ppm; and
d) THFDCA in an amount of less than 30 ppm;
in each case based on the weight of the solids.