Turning Moisture Monitoring into a Competitive Edge in PET Production

From clothing to single-use medical devices to containers for food and liquids, plastics have become essential to modern life. Polyethylene terephthalate (PET), for example, is one of the most common thermoplastics found throughout these industrial supply chains. However, despite its widespread use, PET production – via the condensation reaction of monoethylene glycol and terephthalic acid – is not without challenges. Moisture levels in particular significantly impact the yield of the process. Because of this risk, accurate monitoring and moisture removal are crucial to optimizing profitability.

Currently, manufacturers produce terephthalic acid through the Mid-Century oxidization process. In this process, p-xylene reacts with air in the presence of manganese or cobalt acetate and sodium bromide in an acetic acid solvent. The resulting terephthalic acid is separated from the acetic acid and water mixture for further purification, while the acetic acid is distilled from the water and recycled back to the reactor.

This step requires extra caution with regards to remaining moisture levels. The presence of water deactivates the catalysts found in the p-xylene oxidization reaction. This lowers yields and decreases the overall efficiency of the process. However, thanks to online monitoring solutions like Applied Analytics’ OMA-300-InGaAs analyzer, there does not need to be guesswork to determine if your process stream has moisture levels that are detrimental. By monitoring your acetic acid recycle stream in real time, these potential problems can be identified before they become an issue.

The OMA-300-InGaAs provides superior analysis and flexibility in large part due to its powerful near-infrared Sigma spectrometer. The fiber-optic cables enable unparalleled installation flexibility by allowing the analyzer to be housed at a location separate from the sample point. Moreover, the solid-state design’s lack of moving parts further minimizes routine maintenance and maximizes analyzer uptime.

If you’re interested in learning more about this application or Applied Analytics’ available instrumentation, reach out to one of our experts today and let us provide you with a window into your process.