Rapid Polyolefin Plastic Hydrogenolysis Mediated by Single-Site Heterogeneous Electrophilic/Cationic Organo-group IV Catalysts DOI

Wilson C. Edenfield,

Alexander H. Mason, Qingheng Lai

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 14(1), P. 554 - 565

Published: Dec. 26, 2023

A homologous series of cationic electrophilic group IV metal hydrides (M = Ti, Zr, Hf) created by chemisorption the corresponding MNp4 precursors on highly Brønsted acidic sulfated alumina (AlS) to yield loosely coordinated surface AlS/MNp2 (Np neopentyl) species are systematically characterized ICP, EXAFS/XANES, DRIFTS, and solid-state high-resolution multidimensional NMR spectroscopy (SSNMR), as well energy span DFT computation. With effective stirring, these complexes readily undergo reaction with H2 AlS/M(alkyl)H species, which active for hydrogenolysis diverse commercial polyethylenes, α-olefin-ethylene copolymers, isotactic polypropylene, postconsumer polyolefins including high-density yielding medium small linear branched hydrocarbons at turnover frequencies high 36,300 h–1 200 °C/17 atm M Zr. For given polyolefin conditions, scale approximately Zr > Hf whereas catalyst thermal stability scales ≈ trends qualitatively understandable from analysis. These catalytic results reveal that AlS/Hf(R)H-mediated favors wax-like liquid products, AlS/Zr(R)H-mediated can be tuned between gases liquids. analysis identifies β-alkyl elimination turnover-limiting C–C scission process, is particularly facile in d0 but not so neutrally charged analogues.

Language: Английский

Sustainable developments in polyolefin chemistry: Progress, challenges, and outlook DOI

Xiaoyan Wang,

Yanshan Gao, Yong Tang

et al.

Progress in Polymer Science, Journal Year: 2023, Volume and Issue: 143, P. 101713 - 101713

Published: June 25, 2023

Language: Английский

Citations

80
Chemically recyclable polyolefin-like multiblock polymers DOI
Yucheng Zhao, Emma M. Rettner, Katherine Harry

et al.

Science, Journal Year: 2023, Volume and Issue: 382(6668), P. 310 - 314

Published: Oct. 19, 2023

Polyolefins are the most important and largest volume plastics produced. Unfortunately, enormous use of lack effective disposal or recycling options have created a plastic waste catastrophe. In this work, we report an approach to create chemically recyclable polyolefin-like materials with diverse mechanical properties through construction multiblock polymers from hard soft oligomeric building blocks synthesized ruthenium-mediated ring-opening metathesis polymerization cyclooctenes. The exhibit broad properties, spanning elastomers plastomers thermoplastics, while integrating high melting transition temperature (

Language: Английский

Citations

62
Catalytic Upcycling of Polyolefins DOI Creative Commons
Jia‐Kai Sun,

Jinhu Dong,

Lijun Gao

et al.

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

Citations

29
Circular olefin copolymers made de novo from ethylene and α-olefins DOI Creative Commons
Xingwang Han, Xun Zhang, You‐Yun Zhou

et al.

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Feb. 17, 2024

Abstract Ethylene/α-olefin copolymers are produced in huge scale and widely used, but their after-use disposal has caused plastic pollution problems. Their chemical inertness made re/upcycling difficult. Ideally, PE materials should be de novo to have a circular closed-loop lifecycle. However, synthesis of ethylene/α-olefin copolymers, including high-volume, linear low-density as well high-value olefin elastomers block presents particular challenge due difficulties introducing branches while simultaneously installing recyclability directly using industrial ethylene α-olefin feedstocks. Here we show that coupling coordination copolymerization α-olefins with designed functionalized chain-transfer agent, followed by modular assembly the resulting AB telechelic polyolefin building blocks polycondensation, affords series ester-linked PE-based copolymers. These new not only retain thermomechanical properties also exhibit full circularity via simple transesterification markedly enhanced adhesion polar surfaces.

Language: Английский

Citations

26
A US perspective on closing the carbon cycle to defossilize difficult-to-electrify segments of our economy DOI Creative Commons
Wendy J. Shaw, Michelle K. Kidder, Simon R. Bare

et al.

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

Citations

23
Review on Catalytic Depolymerization of Polyolefin Waste by Hydrogenolysis: State-of-the-Art and Outlook DOI
Abdulrahman Musa,

E. A. Jaseer,

Samir Barman

et al.

Energy & Fuels, Journal Year: 2024, Volume and Issue: 38(3), P. 1676 - 1691

Published: Jan. 22, 2024

Mechanical recycling of plastic waste is not sustainable and inefficient in terms the resources needed to accomplish process, quality materials obtained from this technique substandard. Chemical polymers appears be preferable because technology allows for production new materials. This review compiles most recent research which selected transition metals are used as catalysts hydrogenolytic depolymerization polyolefins a polymer upcycling process. Hydrogenolysis an emerging chemical method that uses transition-metal complexes presence hydrogen cleave C–C bonds substances into shorter hydrocarbons. Transition such Ruthenium (Ru), Platinum (Pt), Nickel (Ni), Cobalt (Co), Zirconium (Zr), Tantalum (Ta), Rhodium (Rh) have been utilized recently type reaction. hydrogenolysis can produce valuable hydrocarbon products, gas/liquid fuels lubricating oils, under relatively milder operational conditions with less environmental impact. The focused on supported metal organometal catalytic system their mechanism polyolefin pathways detailed investigation impact reaction parameters high gasoline, diesel, light lubricants.

Language: Английский

Citations

22
Cationic Tantalum Hydrides Catalyze Hydrogenolysis and Alkane Metathesis Reactions of Paraffins and Polyethylene DOI
Jiaxin Gao,

Lingchao Zhu,

Matthew P. Conley

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(9), P. 4964 - 4968

Published: Feb. 24, 2023

Sulfated aluminum oxide (SAO), a high surface area material containing sulfate anions that behave like weakly coordinating anions, reacts with Ta(═CHtBu)(CH2tBu)3 to form [Ta(CH2tBu)2(O-)2][SAO] (1). Subsequent treatment H2 forms Ta-H+ sites supported on SAO are active in hydrogenolysis and alkane metathesis reactions. In both reactions is more than related neutral Ta-H silica. This reaction chemistry extends melts of high-density polyethylene (HDPE), where converts 30% low molecular weight HDPE (Mn = 2.5 kg mol-1; Đ 3.6) paraffins under conditions. Under conditions this MW fraction 6.2 kDa; 2.3) products (C13-C32). These results show incorporating charge as design element d0 metal hydrides viable strategy increase the rate challenging involving reorganization C-C bonds alkanes.

Language: Английский

Citations

27
Investigation into the Reaction Pathways and Catalyst Deactivation for Polyethylene Hydrogenolysis over Silica-Supported Cobalt Catalysts DOI Creative Commons
Siddhesh S. Borkar, Ryan Helmer, Suraj Panicker

et al.

ACS Sustainable Chemistry & Engineering, Journal Year: 2023, Volume and Issue: 11(27), P. 10142 - 10157

Published: June 27, 2023

Chemical repurposing has emerged as a promising route to valorize "end-of-use" plastic waste and mitigate its release the environment. In this work, we applied silica-supported cobalt (5 wt % Co/SiO2) catalysts produce liquid-range hydrocarbons (C5–C30) in batch phase at 200–300 °C, 20–40 bar H2, 2–36 h with high selectivity investigated reaction pathways, influence of catalyst on product yields selectivity, deactivation mechanisms. Reaction conditions were optimized for improving liquid 275 30 8 time, giving 55% yield (C-mole basis), comprising 75% nonsolid products, gas limited ∼19%. By tracking evolution over time varying surface density, propose multipathway mechanism, including dominant, nonterminal C–C cleavage polymer chain catalyst, which drives selectivity. The also showed recyclability four reactions reduced activity shift toward products after first reaction. It was effectively regenerated by calcination under air 450 °C. We combined reactivity data powder X-ray diffraction (PXRD), thermogravimetric analysis coupled mass spectrometry (TGA-MS), areas via N2 physisorption various fresh, spent, recycled, attribute mainly presence recalcitrant species embedded 10.5–18.5 spent obstructs access active sites increases overshadows carbonaceous coke or reduction Co. Moreover, successfully postconsumer polyethylene (HDPE LDPE) samples. These results move field more sustainable economically viable chemical upcycling plastics.

Language: Английский

Citations

24
Efficient and selective dual-pathway polyolefin hydro-conversion over unexpectedly bifunctional M/TiO2-anatase catalysts DOI Creative Commons
Linxiao Chen, J. Moreira, Laura C. Meyer

et al.

Applied Catalysis B Environment and Energy, Journal Year: 2023, Volume and Issue: 335, P. 122897 - 122897

Published: May 19, 2023

Language: Английский

Citations

23
Highly Selective Upgrading of Polyethylene into Light Aromatics via a Low-Temperature Melting-Catalysis Strategy DOI
Zhe Zhang, Huan Chen, Guixiang Li

et al.

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(4), P. 2552 - 2561

Published: Feb. 2, 2024

The selective upgrading of polyethylene waste into light aromatics is hampered by relatively high C–C bond cleavage temperatures and low product selectivity. Herein, we report a low-temperature melting-catalysis strategy that directly upgrades low-density (LDPE) over commercial ZSM-5 zeolite under mild conditions, eliminating the need for precious metals, solvent, or external H2. Experimental results combined with DFT calculations molecular dynamics simulations revealed molten LDPE microenvironment facilitates intimate LDPE-catalyst contact, promoting primary while suppressing olefin intermediates diffusion out pores. This feature increases residence time subsequent direct cyclization within confined micropores. Moreover, online mass spectra confirmed in situ generated hydrogen from dehydroaromatization reactions plays vital role scission. By optimizing reaction aromatic yield 50.6 wt % an impressive selectivity 90.9% toward benzene, toluene, xylenes was achieved at 280 °C 1 h. not limited to model but also demonstrates remarkable efficiency depolymerization various widely used polyethylene-rich plastics, enabling economically viable environmentally benign chemical recycling path plastic wastes.

Language: Английский

Citations

14