Quality control for Ziegler-Natta catalysis via spectroscopic fingerprinting

Commercial olefin polymerization catalysts are typically produced at a manufacturing site before transport to production facilities for storage and eventual use. During transport and storage, catalysts can deteriorate resulting in decreased catalytic performance due to contact with environmental factors. In this work, a spectroscopic toolbox was developed for quality assurance purposes of a third generation Ziegler-Natta catalyst for ethylene polymerization. A pre-activated, industrial Ziegler-Natta catalyst was exposed singly to heat, dry air, and moisture to study the specific environmental factors. Activity tests were performed with the polymer morphology inspected by SEM and image analysis. Catalyst characterization was conducted using Fourier Transform Infrared spectroscopy with CO and Diffuse Reflectance UV–Vis spectroscopy to relate unique spectroscopic fingerprints to different environmental effects. Reactivity towards gas-phase ethylene polymerization was tested using Diffuse Reflectance Infrared Fourier Transform spectroscopy. This work demonstrates the development of a new spectroscopic methodology useful for quality control in Ziegler-Natta catalysis.