This thesis investigates the catalytic pyrolysis of low-density polyethylene (LDPE) that has been contaminated with limonene, a terpene that is commonly found in orange juice and used as a model contaminant. The selection of limonene is based on its high prevalence in natural products and its strong affinity for polyethylene, as evidenced by several studies. The research aims to evaluate the influence of limonene on the thermal and catalytic degradation of LDPE and to explore how its presence alters the pyrolysis process. Additionally, the effect of ZSM-5 zeolite, a widely used catalyst that is known for enhancing LDPE conversion into valuable hydrocarbons, is assessed.

In this study, low-density polyethylene (LDPE, DOW 310E) and d-limonene (Alfa Aesar) were used to examine the limonene sorption by LDPE. For each experiment, 3 g of LDPE pellets was divided into three aluminum supports (1 g per support) and placed in an airtight desiccator containing 12 mL of limonene in a beaker. The setup was incubated at 40°C, and sorption was monitored by weighing the LDPE after 12 days to determine the absorbed limonene, which ranged between 150 and 160 mg per gram of LDPE. Pyrolysis experiments were conducted at 450°C with a nitrogen flow rate of 200 mL/min.

The results show that limonene influences the distribution of the pyrolysis phases (gas, liquid, and solid), with the liquid fraction being analyzed via Gas Chromatography–Mass Spectrometry (GC-MS). The chemical transformations of the pure and absorbed limonene were also characterized using Fourier Transform Infrared Spectroscopy (FTIR). These findings provide insights into the role of contaminants such as limonene in shaping the efficiency and product distribution of catalytic pyrolysis, contributing to a better understanding of how to valorize contaminated polyethylene waste.