A continuing challenge in modern industrial chemical processes is how the process analytical team can accurately monitor and – more importantly – control the concentrations of reagents and rates of reactions. It is possible to infer conditions within the process using conventional sensors, such as pH probes, thermostats, flow monitors etc…but none of these techniques directly measure the species themselves. The alternative – extracting aliquots for off-line analysis – is costly, slow, and can result in changing the sample, for example when a quench is required. Online and real-time spectroscopy is a very tempting prospect, but most modern spectrometers are designed for laboratory use, and are wholly unsuitable for an industrial setting.<br/>Here we present the design and use of a vibration resistant solid state FTIR spectrometer. The traditional Michelson interferometer has been removed and replaced with an array of mirrors that has no moving parts. This means that the spectrometer has a small footprint, and is almost unaffected by vibration.<br/>We present the results of a number of industrially relevant case studies, of particular interest to industrial chemists. Firstly, we establish the detection limits of water in common solvents (acetone, isopropanol, methanol and acetonitrile), with LoDs in the 10s of ppm. We also investigate specificity between benzene, toluene and xylene, to provide online monitoring of BTX within aromatic hydrocarbon streams. Lastly, we monitor the suitability of the instrument for solvent exchange, with particular focus on the long term stability of chemometric models to monitor concentrations of realistic long terms with minimal changes to the calibration of the spectrometer.

A robust and rugged FTIR spectrometer designed for industrial chemistry

256th National Meeting (2018)

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