{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/132535"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/132535","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Kinetic modeling frameworks for the chemical recycling of polyolefins","abstract":"Plastics have become essential to modern life, yet their durability has led to a global waste challenge (> 360 Mt per year). Among this gigantic among of plastic wastes, most of them have been landfilled, incinerated, or even mismanaged. Only a small portion of them have been recycled. However, current mechanical recycling cannot solve the issue that material properties will degrade during the recycling process. Chemical recycling offers new pathways by converting polymers back into valuable molecules selectively, but the underlying reactions are extremely complex due to a wide range of chain lengths in polymers, different features and functional groups among products, and different phases in a reactor scale that stretch traditional kinetic tools past their limits. This dissertation develops a set of kinetic modeling frameworks for the chemical recycling of polyolefins. First, we examine mass-transfer limits using a diffusion–reaction model that describes how processive catalysts perform inside stagnant and stirred polymer melts. The core of the dissertation then advances the mechanistic modeling for polyethylene (PE) and polypropylene (PP) depolymerization. We begin with a length-agnostic microkinetic model (MKM) that includes all surface and bulk species for a model compound, allowing extraction of rate constants and validation of mechanistic hypotheses from experiments. Then, we started with PP pyrolysis mechanism to build a continuous feature x population balance models (PBMs) that resolve the realistic molecular weight distribution (MWD) while keeping track of the evolution of functional motifs such as double bonds or end groups with a feature balance framework (FBM). We show how FBMs can be coupled to PBMs to follow both detailed kinetics and evolving MWDs across multiple species and predict experimental observables and MWDs.","abstract_html":"Plastics have become essential to modern life, yet their durability has led to a global waste challenge (> 360 Mt per year). Among this gigantic among of plastic wastes, most of them have been landfilled, incinerated, or even mismanaged. Only a small portion of them have been recycled. However, current mechanical recycling cannot solve the issue that material properties will degrade during the recycling process. Chemical recycling offers new pathways by converting polymers back into valuable molecules selectively, but the underlying reactions are extremely complex due to a wide range of chain lengths in polymers, different features and functional groups among products, and different phases in a reactor scale that stretch traditional kinetic tools past their limits. This dissertation develops a set of kinetic modeling frameworks for the chemical recycling of polyolefins. First, we examine mass-transfer limits using a diffusion–reaction model that describes how processive catalysts perform inside stagnant and stirred polymer melts. The core of the dissertation then advances the mechanistic modeling for polyethylene (PE) and polypropylene (PP) depolymerization. We begin with a length-agnostic microkinetic model (MKM) that includes all surface and bulk species for a model compound, allowing extraction of rate constants and validation of mechanistic hypotheses from experiments. Then, we started with PP pyrolysis mechanism to build a continuous feature x population balance models (PBMs) that resolve the realistic molecular weight distribution (MWD) while keeping track of the evolution of functional motifs such as double bonds or end groups with a feature balance framework (FBM). We show how FBMs can be coupled to PBMs to follow both detailed kinetics and evolving MWDs across multiple species and predict experimental observables and MWDs.","abstract_has_math":false,"creators":["Ge, Jiankai"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemical Engineering","degree_department":null,"school":null,"contributors":["Peters, Baron G","Schweizer, Kenneth S","Mironenko, Alexander V","Bickel Rogers, Elizabeth"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-12","date_published":"2025-12","updated_at":"2026-07-22T22:25:07Z","subjects":["Chemical recycling","Kinetics","Modeling","Polyolefins"],"languages":["en"],"rights":["Copyright 2025 Jiankai Ge"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/132535","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Peters, Baron G","Schweizer, Kenneth S","Mironenko, Alexander V","Bickel Rogers, Elizabeth"]},{"key":"dc:creator","label":"Author","values":["Ge, Jiankai"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-12","2025-12-01"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Chemical recycling","Kinetics","Modeling","Polyolefins"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Jiankai Ge"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/132535"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Plastics have become essential to modern life, yet their durability has led to a global waste challenge (> 360 Mt per year). Among this gigantic among of plastic wastes, most of them have been landfilled, incinerated, or even mismanaged. Only a small portion of them have been recycled. However, current mechanical recycling cannot solve the issue that material properties will degrade during the recycling process. Chemical recycling offers new pathways by converting polymers back into valuable molecules selectively, but the underlying reactions are extremely complex due to a wide range of chain lengths in polymers, different features and functional groups among products, and different phases in a reactor scale that stretch traditional kinetic tools past their limits. This dissertation develops a set of kinetic modeling frameworks for the chemical recycling of polyolefins. First, we examine mass-transfer limits using a diffusion–reaction model that describes how processive catalysts perform inside stagnant and stirred polymer melts. The core of the dissertation then advances the mechanistic modeling for polyethylene (PE) and polypropylene (PP) depolymerization. We begin with a length-agnostic microkinetic model (MKM) that includes all surface and bulk species for a model compound, allowing extraction of rate constants and validation of mechanistic hypotheses from experiments. Then, we started with PP pyrolysis mechanism to build a continuous feature x population balance models (PBMs) that resolve the realistic molecular weight distribution (MWD) while keeping track of the evolution of functional motifs such as double bonds or end groups with a feature balance framework (FBM). We show how FBMs can be coupled to PBMs to follow both detailed kinetics and evolving MWDs across multiple species and predict experimental observables and MWDs.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo terms","The student, Jiankai Ge, accepted the attached license on 2025-11-25 at 19:07.","The student, Jiankai Ge, submitted this Dissertation for approval on 2025-11-25 at 19:28.","This Dissertation was approved for publication on 2025-12-01 at 11:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22961 on 2026-02-19 at 18:25:24"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Kinetic modeling frameworks for the chemical recycling of polyolefins"]}]}],"canonical_facts":{"dc:contributor":["Peters, Baron G","Schweizer, Kenneth S","Mironenko, Alexander V","Bickel Rogers, Elizabeth"],"dc:creator":["Ge, Jiankai"],"dc:date":["2025-12","2025-12-01"],"dc:description":["Plastics have become essential to modern life, yet their durability has led to a global waste challenge (> 360 Mt per year). Among this gigantic among of plastic wastes, most of them have been landfilled, incinerated, or even mismanaged. Only a small portion of them have been recycled. However, current mechanical recycling cannot solve the issue that material properties will degrade during the recycling process. Chemical recycling offers new pathways by converting polymers back into valuable molecules selectively, but the underlying reactions are extremely complex due to a wide range of chain lengths in polymers, different features and functional groups among products, and different phases in a reactor scale that stretch traditional kinetic tools past their limits. This dissertation develops a set of kinetic modeling frameworks for the chemical recycling of polyolefins. First, we examine mass-transfer limits using a diffusion–reaction model that describes how processive catalysts perform inside stagnant and stirred polymer melts. The core of the dissertation then advances the mechanistic modeling for polyethylene (PE) and polypropylene (PP) depolymerization. We begin with a length-agnostic microkinetic model (MKM) that includes all surface and bulk species for a model compound, allowing extraction of rate constants and validation of mechanistic hypotheses from experiments. Then, we started with PP pyrolysis mechanism to build a continuous feature x population balance models (PBMs) that resolve the realistic molecular weight distribution (MWD) while keeping track of the evolution of functional motifs such as double bonds or end groups with a feature balance framework (FBM). We show how FBMs can be coupled to PBMs to follow both detailed kinetics and evolving MWDs across multiple species and predict experimental observables and MWDs.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo terms","The student, Jiankai Ge, accepted the attached license on 2025-11-25 at 19:07.","The student, Jiankai Ge, submitted this Dissertation for approval on 2025-11-25 at 19:28.","This Dissertation was approved for publication on 2025-12-01 at 11:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22961 on 2026-02-19 at 18:25:24"],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/132535"],"dc:language":["en"],"dc:rights":["Copyright 2025 Jiankai Ge"],"dc:subject":["Chemical recycling","Kinetics","Modeling","Polyolefins"],"dc:title":["Kinetic modeling frameworks for the chemical recycling of polyolefins"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Chemical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:07Z"}