Sustainable Catalysis for Plastic Waste Valorization: A Case Study in India

Thesis Abstract

This study addresses the escalating challenge of plastic waste accumulation in India and the underutilization of waste plastics as a feedstock for sustainable chemical production. The aim is to develop and validate a catalysis-led valorization framework that integrates waste sorting, catalytic depolymerization, and downstream upgrading to value-added chemicals within Indian urban and industrial contexts. Specific objectives include (i) identifying dominant plastic waste streams in major metropolitan regions (Delhi, Mumbai, Bengaluru) and characterizing their contamination profiles, (ii) developing and benchmarking heterogeneous catalytic systems (zeolite- and metal-supported catalysts) for selective depolymerization of polyethylene terephthalate (PET), polypropylene (PP), and high-density polyethylene (HDPE) into monomers and oligomers, (iii) optimizing reaction parameters (temperature, pressure, catalyst loading, solvent or solvent-free conditions) using factorial experimental design, (iv) evaluating process integration with solvent extraction and catalytic upcycling to polyols, fuels, and petrochemical precursors, and (v) assessing techno-economic and environmental implications under Indian regulatory and market conditions. The study adopts a mixed-methods research design, combining quantitative experimental work with qualitative stakeholder insights. The population comprises catalytic materials researchers, municipal solid waste managers, and polymer processing industry professionals in India. A stratified random sample of 30 municipal sites will be surveyed to quantify waste composition, while 12 pilot-scale catalytic runs will be conducted to evaluate performance. Data collection instruments include gas chromatography–mass spectrometry (GC–MS) and carbon-13 nuclear magnetic resonance (13C NMR) for product distribution, Brunauer–Emmett–Teller (BET) surface area analysis for catalyst characterization, inductively coupled plasma optical emission spectrometry (ICP-OES) for metal loadings, and high-performance liquid chromatography (HPLC) for polyol purity assessment. Statistical analyses will employ response surface methodology (RSM) and central composite design (CCD) to optimize reaction conditions, while regression analyses will quantify relationships between catalyst properties and process yields. Life cycle assessment (LCA) will be conducted following ISO 14040 standards, and techno-economic analysis (TEA) will estimate levelized production costs and break-even points under varying feedstock prices and policy incentives. The theoretical framework integrates the principles of sustainable chemistry and the catalytic reaction engineering theory, with a focus on structure–activity relationships and reaction pathway control mediated by acidic and bifunctional active sites. The study anticipates producing a detailed performance map for catalysts comprising zeolite Y, ZSM-5, and supported ruthenium or nickel catalysts, alongside process designs for a modular, decentralized valorization unit suitable for urban waste processing hubs. Expected findings include (i) a quantified dominance of PET and PP fractions in Indian municipal waste streams and their corresponding impurity profiles, (ii) identification of catalyst configurations that maximize selective C–O and C–C scission to yield terephthalic monomers, benzene-derived aromatics, and lower-value fuels with minimal char formation, (iii) optimal operating windows that balance conversion, selectivity, and catalyst stability, (iv) demonstrated techno-economic viability under policy scenarios including extended producer responsibility and waste-to-energy tax credits, and (v) a robust LCA showing net environmental ben- efits relative to conventional landfill and incineration routes. The study contributes to knowledge by integrating municipal waste characterization with catalyst development and process integration in a realistic Indian setting, bridging laboratory discovery and scalable, policy-relevant solutions. The final conclusions are expected to confirm the feasibility of modular catalytic valorization chains within Indian cities, provide design guidelines for pilot facilities, and offer policy-oriented recommendations to support feedstock collection, catalyst procurement, and end-product markets. Recommendations include adopting standardized waste sorting protocols at source, deploying pilot plants with 5–10 tonne per day throughput, incentivizing recyclates through green chemistry certifications, and establishing public–private partnerships to sustain decentralized valorization ecosystems.