Abstract:
Phthalic anhydride is manufactured by the partial oxidation of ortho xylene in the presence
of V205/TiO2 catalyst. In the residue, maleic acid, benzoic acid (BA), toluic acid and traces
of other organic compounds are present in the byproduct stream. The waste stream is in the
form of slurry at high temperature and is solidified at room temperature. Benzoic acid was
selectively removed from the solid waste of phthalic anhydride production industry.
In the present work, the separation of benzoic acid from crude sample has been performed
by using physical and chemical techniques. In physical methods re-crystallization (RE),
liquid-liquid extraction (LLE) as well as re-crystallization followed by liquid-liquid
extraction (RE, LLE) and liquid-liquid extraction followed by re-crystallization (LLE, RE)
have been studied. In another attempt chemical derivatization (CD) has been performed for
the purification purposes. The operation has been carried out at the atmospheric pressure
with operating temperatures of 100⁰C and 25⁰C in physical processes (RE) and (LLE)
respectively while in chemical derivatization it ranges from 72⁰C to 100⁰C. The
characterization of the samples was accomplished by melting point determination, Gas
chromatography (GC), Mass spectrometry (MS) and Fourier transform infrared
spectroscopy (FTIR) . RE technique gives high recovery with compromised purity.CD is
found to be generating high purity but with only 58% recovery. While LLE is associated
with optimized purity and recovery. Almost 99% of the purity was achieved by CD , LLE ,
RE followed LLE and LLE followed by RE.
