Method for preparing chromium(III) pyridine-2-carboxylate using 2-OP rectification residues

Abstract

A method for preparing chromium(III) pyridine-2-carboxylate using 2-OP rectification residues, including: subjecting the 2-OP rectification residues to in-situ catalytic pyrolysis and vacuum distillation, room-temperature crystallization and separation, recrystallization and dehydration, alkali-catalyzed hydrolysis, acidification and complexation, and separation, washing and drying to prepare a chromium(III) pyridine-2-carboxylate product, of which a yield is greater than 50% of the weight of the 2-OP rectification residues. The acidification and complexation includes: cooling the aqueous solution containing sodium pyridine-2-carboxylate obtained from the alkali-catalyzed hydrolysis to a temperature below 50° C.; adjusting the aqueous solution to pH 3.0-8.5 with 5-50 wt % dilute H2SO4 or 3-30 wt % dilute HCl followed by batchwise addition of CrCl3, Cr(NO3)3 or Cr2(SO4)3 for complexation at 20-70° C. to obtain a slurry containing chromium(III) pyridine-2-carboxylate, which is separated, washed and dried to obtain a chromium(III) pyridine-2-carboxylate product with a purity of 98.5% or more.

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