Application Examples for the Chemical and Pharmaceutical Industry

Determination of the Purity of Monoethylene Glycol
Clariant is one of the leading European producers of ethylene oxide as well as fatty amines and their derivatives. These products are all manufactured at the Gendorf production site in Germany. Monoethylene glycol (MEG) is used for the manufacture of polyester fibres and polyethylene terephthalate (PET) as well as plastics antifreeze and deicing agents.
For the determination of the purity of monoethylene glycol,
a UV spectrometer was installed.
Impurities after the production process can be very well detected in the UV region at 220nm. This needs solarization stable UV light guides and because of higher damping losses in this spectral region long fiber optic distances have to be avoided. Therefore, the measurement system must be located close to a pipe or vessel. The CompactSpec^® II EEx process spectrometer system can be installed directly in the production area and thus avoids long light guides. Damping losses and costs for installation are therefore minimized.

Inline Color Measurement of Fatty Alcohols
Cognis is a leading company in specialty chemicals. Utilizing its 160 years of experience in oleochemicals, Cognis develops innovative products for personal care, home care, and modern nutrition, as well as high-performance products for numerous industrial markets. The superior quality of Cognis natural sourced products is the key to their success. They spent great effort to maintain this quality, from careful selection of raw materials to state-of-the-art process technology.
The color of the fatty alcohols is a major quality criteria. In the past, samples for analysis were taken from the process stream and measured in the lab. To reduce this time consuming and cost-intensive procedure the plant applied an inline spectrometer system. The color is determined as Lovibond number. The flow through cells with a path length of 50mm are connected with the instrument via fiber optics. The sample temperature is 60°C. To eliminate the effect of soiled windows an offset correction is done before colorimetric data evaluation. For process communication the Profibus DP protocol is used.

Inline Measurements of a Polymerization Process
The graphic shows NIR spectra of a copolymerisation reaction during a run over a period of 5 hours. The individual measurements were taken by means of a transmission process probe with integration times of only a few milliseconds each. Regression calculations were performed by a chemometrical software tool for the parameters ‘Total Throughput’ as well as for the components ‘Styrene’ and ‘BA’.
In the beginning the strong bubble generation, which is typical for this reaction, had a very negative effect on the reproducibility of the measurements. A special software algorithm, based on the very short data acquisition times of a detector array spectrometer, corrupted spectra are identified already during the recording process by detecting the baseline shift. These spectra are neglected for further data evaluation. Even at extreme process conditions stable results can be achieved.