Understanding the Structure–Activity Relationships in Catalytic Conversion of Polyolefin Plastics by Zeolite-Based Catalysts: A Critical Review

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(24), P. 14882 - 14901

Published: Nov. 23, 2022

Polyolefins, the largest used commodity plastics in world, find extensive application many fields. However, most end up landfills or incineration, leading to severe ecological crises, environmental pollution, and serious resource waste problems. As representatives on chemical upcycling of polyolefin fuels bulk/fine chemicals, catalytic cracking hydrocracking based zeolite metal/zeolite composite catalysts are considered effective paths due their large capacity strong adaptability existing petrochemical equipment. After an overview reaction mechanisms pyrolysis cracking, this review aims comprehensively discuss influence catalyst structure (acidity, pore structure, morphology) activity, selectivity, stability particularly emphasizing importance for matching acidity target product formation. Subsequently, structure–activity relationship between metal site zeolite's acid is also discussed. In end, emerging opportunities challenges proposed promote a more efficient way upcycling.

Language: Английский

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Plastic Waste Valorization by Leveraging Multidisciplinary Catalytic Technologies

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(15), P. 9307 - 9324

Published: July 18, 2022

Plastic waste triggers a series of concerns because its disruptive impact on the environment and ecosystem. From point view catalysis, however, end-of-life plastics can be seen as an untapped feedstock for preparation value-added products. Thus, development diversified catalytic approaches valorization is urgent. Previous reviews this field have systematically summarized progress made plastic reclamation. In review, we emphasize design processes by leveraging state-of-the-art technologies from other developed fields to derive valuable polymers, functional materials, chemicals plastics. The principles, mechanisms, opportunities chemical (thermo-, electro-, photocatalytic) well biocatalytic ones are discussed, which may provide more insights future processes. Finally, outlooks perspectives accelerate toward feasible economy discussed.

Language: Английский

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Role of Bifunctional Ru/Acid Catalysts in the Selective Hydrocracking of Polyethylene and Polypropylene Waste to Liquid Hydrocarbons

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(22), P. 13969 - 13979

Published: Oct. 31, 2022

Hydrogenolysis of C–C bonds over Ru-based catalysts has emerged as a deconstruction strategy to convert single-use polyolefin waste liquid alkanes at relatively mild conditions, but this approach exhibits limitations, including methane formation resulting from terminal bond scission. In study, variety were investigated for the reductive polyethylene (PE) and polypropylene (PP) identify supports that promote nonterminal We found Ru nanoparticles supported on Brønsted-acidic zeolites with faujasite (FAU) Beta (BEA) topologies highly active cleavage in PE PP, exhibiting improved yields suppressed formation. For PE, supporting ruthenium (5 wt %) FAU increased 67% compared 33% an inert silica support % Ru/SiO2) 200 °C, 16 h, under 30 bar H2. A dramatic selectivity enhancement toward hydrocarbons was also observed PP Ru/FAU Ru/BEA Ru/SiO2. To understand origin improvement, combination ex situ operando characterization techniques used reveal both catalyst structure acidity play key roles conversion. Operando X-ray absorption spectroscopy studies model polyolefins Ru-supported varying levels revealed local chemical environment Ru[0] during reaction is consistent across multiple acidic supports, although onset reduction synthesis varies different supports. These results, combined reactivity data, demonstrate importance acid-noble metal cooperativity promoting selective scission shifts mechanism hydrogenolysis ideal hydrocracking.

Language: Английский

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A two-stage strategy for upcycling chlorine-contaminated plastic waste

Nature Sustainability, Journal Year: 2023, Volume and Issue: 6(10), P. 1258 - 1267

Published: June 22, 2023

Abstract Chemical upcycling of polyolefin plastic waste to lubricant, wax and fuel-range hydrocarbons over metal-based catalysts is a crucial technological solution the enormous environmental threat posed by waste. However, currently available methods are incompatible with chlorine-contaminated feedstocks. Here we report two-stage strategy for polypropylene. First, magnesia–alumina mixed oxide at 30 bar H 2 250 °C serves as chlorine trap rapidly forming solid chloride, resulting in nearly complete extraction from melt. This enables up 10% polyvinyl chloride content lubricants ruthenium-based catalysts, second stage. The also applicable chlorinated aromatics alkanes. proposed renders hydrocracking hydrogenolysis less sensitive impurities feedstocks while eliminating HCl emissions contamination products. It could incentivize further progress plastics upcycling.

Language: Английский

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Recent Advances in Catalytic Chemical Recycling of Polyolefins

ChemCatChem, Journal Year: 2023, Volume and Issue: 15(13)

Published: March 29, 2023

Abstract Polyolefins and especially polyethylenes (LLDPE, LDPE HDPE) polypropylene (PP) contribute a great deal to the growing amounts of plastic waste with combined production share almost 50 % by mass. While being universally applicable, they are mainly used for short‐lived packaging materials that constitute over 60 annual post‐consumer waste. Thus, disproportionately high polyolefins end up as (PCW) management strategies these particularly inert plastics needed. This necessity has promoted research effort dealing valorization discarded but, nevertheless, valuable materials. review aims highlight scientific advances made in chemical polyolefin recycling recent years, focusing, though not exclusively, on catalytic processes recycle various means at more moderate temperatures compared pyrolysis such deconstructing polymer objective upcycling mind or transformation give access functional chemicals.

Language: Английский

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Upcycling of Plastic Waste Using Photo-, Electro-, and Photoelectrocatalytic Approaches: A Way toward Circular Economy

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(7), P. 4865 - 4926

Published: March 18, 2024

Rapid industrialization and development have led to a tremendous increase in the use of various types plastic commodities daily life. For past several years, pollution has become global issue, posing serious threat mankind. The primary issue with increasing is lack proper management which created huge havoc environment. From initial phase waste management, been discarded, recycled, downcycled, or dumped into landfills large proportion, causing extreme damage ecosystem. Conventionally, treated via thermal processes such as pyrolysis incineration plants require amount capital and, therefore, harms aim circular economy. Chemical upcycling gaining attention high-potential catalytic strategy convert plastics, polyethylene terephthalate, polyethylene, polystyrene, etc. fuels, functionalized polymers, other value-added chemicals having direct impact on affordability viability. In this review, we focused photocatalysis, electrocatalysis, photoelectrocatalysis effective efficient technologies. These approaches can lower dependence nonrenewable resources are more environmentally friendly contrast conventional approaches. This review elaborately discusses pros cons provides detailed overview potential renewable energy-driven for conversion wastes valuable fuels commodity chemicals, along challenges future directions emerging approach treatment.

Language: Английский

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Upcycling of polyethylene to gasoline through a self-supplied hydrogen strategy in a layered self-pillared zeolite

Nature Chemistry, Journal Year: 2024, Volume and Issue: 16(6), P. 871 - 880

Published: April 9, 2024

Abstract Conversion of plastic wastes to valuable carbon resources without using noble metal catalysts or external hydrogen remains a challenging task. Here we report layered self-pillared zeolite that enables the conversion polyethylene gasoline with remarkable selectivity 99% and yields >80% in 4 h at 240 °C. The liquid product is primarily composed branched alkanes (selectivity 72%), affording high research octane number 88.0 comparable commercial (86.6). In situ inelastic neutron scattering, small-angle solid-state nuclear magnetic resonance, X-ray absorption spectroscopy isotope-labelling experiments reveal activation promoted by open framework tri-coordinated Al sites zeolite, followed β-scission isomerization on Brönsted acids sites, accompanied hydride transfer over through self-supplied pathway yield alkanes. This study shows potential materials enabling upcycling wastes.

Language: Английский

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Stable Interfacial Ruthenium Species for Highly Efficient Polyolefin Upcycling

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 7076 - 7087

Published: March 1, 2024

The present polyolefin hydrogenolysis recycling cases acknowledge that zerovalent Ru exhibits high catalytic activity. A pivotal rationale behind this assertion lies in the propensity of majority species to undergo reduction within milieu. Nonetheless, suitability as an optimal structural configuration for accommodating multiple elementary reactions remains ambiguous. Here, we have constructed stable Ru0–Ruδ+ complex species, even under reaction conditions, through surface ligand engineering commercially available Ru/C catalysts. Our findings unequivocally demonstrate surface-ligated can be stabilized form a Ruδ+ state, which, turn, engenders perturbation σ bond electron distribution carbon chain, ultimately boosting rate-determining step C–C scission. optimized catalysts reach solid conversion rate 609 g·gRu–1·h–1 polyethylene. This achievement represents 4.18-fold enhancement relative pristine catalyst while concurrently preserving remarkable 94% selectivity toward valued liquid alkanes. Of utmost significance, extended gentle mixing solution at room temperature, thus rendering it amenable swift integration into industrial processes involving degradation.

Language: Английский

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Catalytic Upcycling of Polyolefins

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(16), P. 9457 - 9579

Published: Aug. 16, 2024

The large production volumes of commodity polyolefins (specifically, polyethylene, polypropylene, polystyrene, and poly(vinyl chloride)), in conjunction with their low unit values multitude short-term uses, have resulted a significant pressing waste management challenge. Only small fraction these is currently mechanically recycled, the rest being incinerated, accumulating landfills, or leaking into natural environment. Since are energy-rich materials, there considerable interest recouping some chemical value while simultaneously motivating more responsible end-of-life management. An emerging strategy catalytic depolymerization, which portion C-C bonds polyolefin backbone broken assistance catalyst and, cases, additional molecule reagents. When products molecules materials higher own right, as feedstocks, process called upcycling. This review summarizes recent progress for four major upcycling strategies: hydrogenolysis, (hydro)cracking, tandem processes involving metathesis, selective oxidation. Key considerations include macromolecular reaction mechanisms relative to mechanisms, design transformations, effect conditions on product selectivity. Metrics describing critically evaluated, an outlook future advances described.

Language: Английский

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A US perspective on closing the carbon cycle to defossilize difficult-to-electrify segments of our economy

Nature Reviews Chemistry, Journal Year: 2024, Volume and Issue: 8(5), P. 376 - 400

Published: May 1, 2024

Electrification to reduce or eliminate greenhouse gas emissions is essential mitigate climate change. However, a substantial portion of our manufacturing and transportation infrastructure will be difficult electrify and/or continue use carbon as key component, including areas in aviation, heavy-duty marine transportation, the chemical industry. In this Roadmap, we explore how multidisciplinary approaches enable us close cycle create circular economy by defossilizing these difficult-to-electrify those that need carbon. We discuss two for this: developing alternatives improving ability reuse carbon, enabled separations. Furthermore, posit co-design use-driven fundamental science are reach aggressive reduction targets. To achieve net-zero emissions, must industries electrify. Developing needed provide non-fossil accelerate advances towards defossilization.

Language: Английский

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