Off-campus SJSU users: To download campus access theses, please use the following link to log into our proxy server with your SJSU library user name and PIN.

Publication Date

Fall 2025

Degree Type

Thesis - Campus Access Only

Degree Name

Master of Science (MS)

Department

Chemical and Materials Engineering

Advisor

Christopher Lew; Katy Kao; Yanika Schneider

Abstract

The accumulation of plastic waste has created an urgent need for more sustainable recycling methods. Catalytic pyrolysis presents a promising approach, particularly when enhanced with zeolite catalysts that can lower degradation temperatures and improve product selectivity. This study investigates the catalytic effect of zeolites on the thermal degradation of polyethylene (PE), focusing on the structural and compositional features that influence zeolite acidity and catalytic performance. Thermogravimetric analysis (TGA) was employed to compare the catalytic influence of beta, MFI, CHA, and FAU zeolites with varying crystal sizes on the thermal degradation behavior of PE. Both micro- and nanocrystalline zeolites exhibited catalytic activity, lowering the degradation temperature from 504.1 ± 0.6 °C to as low as 277.8 ± 9.5 °C. However, zeolites possessing characteristics typically associated with higher acidity, such as lower Si/Al ratios, larger pores, and smaller crystal sizes, did not consistently enhance catalytic performance. Statistical analyses confirmed that protonated zeolites produced significantly greater reductions in degradation temperature (p < 0.01), followed by nanocrystalline variants, whereas the Si/Al ratio and pore size showed a lesser influence. These findings suggest that catalytic behavior is not solely governed by intrinsic acidity, but by the interplay among pore dimensionality, acid-site accessibility, and morphology, which collectively influence zeolite-polymer interactions and degradation efficiency.

Download

Share

COinS