Sustainable Catalysis for Plastic Upcycling in Electronics Waste Streams

Thesis Abstract

The rapid growth of electronics waste (e-waste) and its plastic components poses severe environmental and health challenges due to the accumulation of persistent polymers and additives that resist conventional recycling. This study addresses the problem of low-value recovery from mixed plastic fractions in e-waste streams by developing sustainable catalytic routes for upcycling plastics into high-value monomers and fuels, thereby aligning waste valorization with circular economy objectives. The aims are to (i) identify viable plastic fractions within selected e-waste streams, (ii) design and optimize heterogeneous catalysts capable of converting polyolefins and halogenated polymers present in electronics waste into useful chemicals under mild conditions, and (iii) assess environmental and techno-economic performance of the proposed routes. Specific objectives include (a) characterizing e-waste plastics from a regional recycling facility with a sample size of 120 discrete batches collected over 12 months, (b) synthesizing and screening metal–organic framework (MOF)-derived bifunctional catalysts and earth-abundant metal catalysts (e.g., Ni, Fe) for hydrocracking and depolymerization reactions, (c) optimizing reaction conditions (temperature 250–350°C, pressure 2–8 MPa H2 or supercritical CO2) using response surface methodology (RSM) to maximize monomer yield, (d) evaluating catalyst stability and deactivation mechanisms via TEM, XRD, TGA, and XPS, and (e) conducting life cycle assessment (LCA) and techno-economic analysis (TEA) to compare the proposed routes with conventional mechanical recycling. The methodology adopts a mixed-methods design integrating experimental catalysis with cheminformatics and sustainability assessment. The population comprises plastics recovered from end-of-life electronics collected from three regional recycling centers; a stratified sampling approach yields 10 representative feedstocks for catalytic testing. Data collection instruments include gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography (HPLC) for product analysis, inductively coupled plasma optical emission spectroscopy (ICP-OES) for catalyst composition, Brunauer–Emmett–Teller (BET) surface area analysis, and calibrated calorimetry for energy input assessments. Validity and reliability are ensured through replication (triplicate runs per condition), calibration against authenticated standard references, and cross-validation of product distributions with GC–MS libraries. Analytical methods include multivariate regression and ANOVA to quantify the influence of catalyst properties and reaction parameters on product selectivity, density functional theory (DFT) calculations to elucidate mechanistic pathways, and statistical process control to monitor reproducibility. A conceptual framework combining the Theory of Planned Behavior for stakeholder acceptance and the Circular Economy model guides the interpretation of environmental and socio-economic implications. The expected findings indicate that bifunctional catalysts derived from MOF-derived materials enable selective cleavage of C–C and C–O bonds in polyolefins and polyesters within e-waste plastics, achieving monomer yields above 40% under optimized conditions with less than 10% formation of char, and showing enhanced turnover frequencies after regeneration cycles. It is anticipated that DOT (degree of polymerization and tacticity) effects will influence selectivity, and that catalysts will exhibit varying lifetimes depending on halogen content, with deactivation linked to coke deposition and metal physisorption. The study contributes to knowledge by providing a scalable, catalyst-driven pathway for turning low-value e-waste plastics into high-value chemical commodities, integrating catalytic design with lifecycle sustainability metrics, and offering a framework for industrial pilots in electronics recycling facilities. The main conclusion is that sustainable catalysis can materially improve the upcycling potential of e-waste plastics while reducing energy use and environmental impact relative to conventional routes. Recommendations include (i) scaling pilot reactors to 100–250 kg per batch with integrated feed-preparation and impurity mitigation, (ii) optimization of catalyst regeneration protocols to minimize deactivation, and (iii) policy and governance guidance to harmonize e-waste feedstock standards and encourage industry adoption through standardized LCA benchmarks.