title: Monitoring of itaconic acid hydrogenation in a trickle bed reactor using fiber-optic coupled near-infrared spectroscopy.
abstract: Near-infrared (NIR) spectroscopy has been applied to determine the conversion of itaconic acid in the effluent stream of a trickle bed reactor. Hydrogenation of itaconic to methyl succinic acid was carried out, with the trickle bed operating in recycle mode. For the first time, NIR spectra of itaconic and methyl succinic acids in aqueous solution, and aqueous mixtures withdrawn from the reactor over a range of reaction times, have been recorded using a fiberoptic sampling probe. The infrared spectra displayed a clear isolated absorption band at a wavenumber of 6186 cm(-1) (wavelength 1.617 microm) resulting from the =C-H bonds of itaconic acid, which was found to decrease in intensity with increasing reaction time. The feature could be more clearly observed from plots of the first derivatives of the spectra. A partial least-squares (PLS) model was developed from the spectra of 13 reference samples and was used successfully to calculate the concentration of the two acids in the reactor effluent solution. Itaconic acid conversions of 23-29% were calculated after 360 min of reaction time. The potential of FT-NIR with fiber-optic sampling for remote monitoring of three-phase catalytic reactors and validation of catalytic reactor models is highlighted in the paper.
authors.affiliation: Centre for Formulation Engineering, Department of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Joseph
authors.initials: J
authors.lastname: Wood
authors.forename: Paul H
authors.initials: PH
authors.lastname: Turner
mesh_terms: D019149:Bioreactors; D002138:Calibration; D002384:Catalysis; D002617:Chemical Industry / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006859:Hydrogen / Q000737:chemistry*; D006865:Hydrogenation; D055100:Optical Fibers; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation* / Q000379:methods*; D013386:Succinates / Q000032:analysis* / Q000138:chemical synthesis / Q000145:classification; D014159:Transducers
chemical_list: D013386:Succinates; D006859:Hydrogen; C005229:itaconic acid