Oxygen Chemistry in Polymer Fouling: Insights from Multiphase Detailed Kinetic Modeling

Polymer fouling is a pervasive challenge in the downstream processes of steam cracking. Molecular oxygen is likely to present and is known to strongly affect various polymerization processes, yet the role of oxygen in distillation column fouling remains poorly understood. Building upon the foundations laid in our preceding study [Pang et al., Ind. Eng. Chem. Res. 2023, 62, 36, 14266–14285], this work presents a detailed kinetic modeling approach to investigate the impact of oxygen on polymer fouling in a typical debutanizer. The fouling model incorporates molecular oxygen as a primary source of contamination in the feedstock and encompasses a comprehensive network of chemical reactions, phase equilibria, and interphase transport phenomena. Critical model parameters are derived from quantum chemistry calculations to ensure accuracy. The sensitivity of fouling rates to varying levels of dissolved oxygen is examined. We find that even small traces (ppm level) of the molecular oxygen contaminant in the feedstock can significantly accelerate fouling growth in the colder section. Furthermore, the dominant pathways of fouling are observed to shift over time due to diffusion limitations. This study showcases the power and adaptability of predictive detailed kinetic modeling in deciphering the mechanistic fundamentals of polymer fouling.