Expanding plastics recycling technologies: chemical aspects, technology status and challenges

Green Chemistry, Journal Year: 2022, Volume and Issue: 24(23), P. 8899 - 9002

Published: Jan. 1, 2022

This paper reviewed the entire life cycle of plastics and options for management plastic waste to address barriers industrial chemical recycling further provide perceptions on possible opportunities with such materials.

Language: Английский

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Catalytic deconstruction of waste polyethylene with ethylene to form propylene

Science, Journal Year: 2022, Volume and Issue: 377(6614), P. 1561 - 1566

Published: Sept. 29, 2022

The conversion of polyolefins to monomers would create a valuable carbon feedstock from the largest fraction waste plastic. However, breakdown main chains in these polymers requires cleavage carbon–carbon bonds that tend resist selective chemical transformations. Here, we report production propylene by partial dehydrogenation polyethylene and tandem isomerizing ethenolysis desaturated chain. Dehydrogenation high-density with either an iridium-pincer complex or platinum/zinc supported on silica as catalysts yielded dehydrogenated material containing up 3.2% internal olefins; combination second-generation Hoveyda-Grubbs metathesis catalyst [PdP( t Bu) 3 (μ-Br)] 2 isomerization selectively degraded this unsaturated polymer yields exceeding 80%. These results show promise for application mild catalysis deconstruct otherwise stable polyolefins.

Language: Английский

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Rational Design of Chemical Catalysis for Plastic Recycling

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(8), P. 4659 - 4679

Published: April 5, 2022

Plastics are indispensable, but their pollution is triggering a global environmental crisis. Although many end-of-life catalytic options have involved converting plastics into valuable products, deep understanding of the relationship between polymer structure and recycling performance significant urgently needed. Here, we start with primer polymeric chain structures on chemical discuss structure–performance polymer, catalyst, reaction. Specifically, development challenges re/upcycling waste PET polyolefins discussed in-depth. In addition, also present some prospects for innovations in catalyst synthesis reaction engineering basis relationship. The discussion ends brief perspective future plastic re/upcycling. Overall, intelligent catalysis design necessary incentivizing relieving burden plastics.

Language: Английский

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Biodegradation of polyethylene and polystyrene: From microbial deterioration to enzyme discovery

Biotechnology Advances, Journal Year: 2022, Volume and Issue: 60, P. 107991 - 107991

Published: May 31, 2022

The global production of plastics has continuously been soaring over the last decades due to their extensive use in our daily life and industries. Although synthetic offer great advantages from packaging construction electronics, low biodegradability induce serious plastic pollution that damage environment, human health make irreversible changes ecological cycle. In particular, containing only carbon-carbon (C-C) backbone are less susceptible degradation lack hydrolysable groups. representative polyethylene (PE) polystyrene (PS) account for about 40% total production. Various chemical biological processes with potential have developed recycle reuse, but biodegradation seems be most attractive eco-friendly method combat this growing environmental problem. review, we first summarize current advances PE PS biodegradation, including isolation microbes degrading enzymes different sources. Next, state-of-the-art techniques used evaluating monitoring degradation, scientific toolboxes enzyme discovery as well challenges strategies intensively discussed. return, it inspires a further technological exploration expanding diversity species enzymes, disclosing essential pathways developing new approaches utilize waste feedstock recycling upcycling.

Language: Английский

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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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Disordered, Sub-Nanometer Ru Structures on CeO₂ are Highly Efficient and Selective Catalysts in Polymer Upcycling by Hydrogenolysis

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(8), P. 4618 - 4627

Published: April 5, 2022

Nondegradable polyolefin plastics pose severe environmental threats and thus demand efficient upcycling technologies. In this work, we discovered that low-loading (≤0.25 wt %) Ru/CeO2 exhibits remarkable catalytic performance in the hydrogenolysis of polypropylene (PP), polyethylene (PE), n-C16H34 is superior to high-loading (≥0.5 Ru/CeO2. They possess high PP conversion efficiency (sevenfold increase over current literature reports), low selectivity toward undesired CH4, good isomerization ability. range, intrinsic activity Ru increases as particle size decreases, opposite trend range. Detailed characterization revealed abrupt changes behaviors coincide with species transitioning from well-defined highly disordered structures domain. The were shown be sub-nanometer cationic. Mechanistically, regioselectivity rate dependence on hydrogen pressure C–C bond cleavage are different low- Ru/CeO2, both explained by higher coverage adsorbed (*H) This work reveals disordered, sub-nanometer, cationic hydrogenolysis, opening immense opportunities develop effective, selective, versatile catalysts for plastic upcycling.

Language: Английский

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Current Prospects for Plastic Waste Treatment

Polymers, Journal Year: 2022, Volume and Issue: 14(15), P. 3133 - 3133

Published: July 31, 2022

The excessive amount of global plastic produced over the past century, together with poor waste management, has raised concerns about environmental sustainability. Plastic recycling become a practical approach for diminishing and maintaining sustainability among management methods. Chemical mechanical are typical approaches to waste, simple process, low cost, environmentally friendly potential profitability. Several materials, such as polypropylene, polystyrene, polyvinyl chloride, high-density polyethylene, low-density polyurethanes, can be recycled chemical approaches. Nevertheless, due waste’s varying physical properties, separation becomes challenge. Hence, reliable effective technology is critical increasing value rate. Integrating technologies would an efficient method reducing accumulation contaminants by especially in industrial uses. This review addresses recent advances technology, mainly recycling. article also discusses current various materials.

Language: Английский

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Sustainable chemical upcycling of waste polyolefins by heterogeneous catalysis

SusMat, Journal Year: 2022, Volume and Issue: 2(2), P. 161 - 185

Published: April 1, 2022

Abstract The mass production of disposable polyolefin products has led to serious plastic pollution and an imbalance between manufacturing recycling. Given these challenges, the chemical upcycling waste polyolefins attracted extensive attention due its high efficiency economic benefits. Herein, we review development in heterogeneous catalysis. status quo recycling is first discussed. We then introduce advanced strategies for view different value‐added discuss their challenges prospects. Our in‐depth analysis centers on catalytic mechanism design principle catalysts. Finally, outlook promising directions facilitate degradation process via polymer catalyst optimized engineering. Innovative are expected promote polyolefins, bringing great promise sustainable society.

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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Nanocatalyzed upcycling of the plastic wastes for a circular economy

Coordination Chemistry Reviews, Journal Year: 2022, Volume and Issue: 458, P. 214422 - 214422

Published: Jan. 31, 2022

Language: Английский

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