Population balance models for polymer upcycling: signatures of the mechanism in the molecular weight evolution

Yappert, Ryan; Peters, Baron

doi:10.1039/d2ta04628h

Cited by 9 publications

(24 citation statements)

References 91 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…34 The difference between initial M n and after a conversion also provides the number of C−C bonds cleaved. 24,39 Despite errors associated with combining data from separate measurements of each component of the reaction mixture, we find reasonable agreement (<20% greater C−C cleavage from H 2 consumption) between this C−C bond cleavage and the value calculated from H 2 consumption.…”

Section: ■ Resultsmentioning

confidence: 62%

“…Branching and chain length can affect the reaction mechanism of small molecule conversions − as well as the physical properties of polymers, leading to complex behavior. Non-processive catalysts generally require longer times for samples with higher MW, leading to time-dependent distributions. ,,,,,, For example, Ru/CeO 2 required shorter times for the conversion of lower MW LDPE than higher MW samples . Polymer branching also affects reactivity.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the mass-specific activity and TOF for Pt/MCM-48-catalyzed C–C cleavage are higher than for Pt/SiO 2 . This behavior is understood in terms of the rate of chain end migration to an internal carbon bonded to Pt (e.g., via quasi-desorption/adsorption equilibria) competing with C–C bond cleavage in the slower hydrogenolysis catalyst …”

Section: Discussionmentioning

confidence: 99%

“…Also, the mesoporous silica-embedded Pt NPs resist deactivation. Importantly, mSiO 2 /Pt/SiO 2 affords conversion-independent products, in contrast to the number-average molecular weight ( M n ) decreasing with time . The porous architecture further favors polymer deconstruction over cleavage of paraffins …”

Section: Introductionmentioning

confidence: 99%

“…Importantly, mSiO 2 / Pt/SiO 2 affords conversion-independent products, in contrast to the number-average molecular weight (M n ) decreasing with time. 24 The porous architecture further favors polymer deconstruction over cleavage of paraffins. 23 The latter two features are signatures of a processive deconstruction mechanism, which is generally supported by experimental, spectroscopic, and theoretical studies of mSiO 2 / Pt/SiO 2 -catalyzed conversions.…”

Section: ■ Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Two Mesoporous Domains Are Better Than One for Catalytic Deconstruction of Polyolefins

Tennakoon,

Wu,

Meirow

et al. 2023

J. Am. Chem. Soc.

View full text Add to dashboard Cite

Catalytic hydrogenolysis of polyolefins into valuable liquid, oil, or wax-like hydrocarbon chains for second-life applications is typically accompanied by the hydrogen-wasting co-formation of low value volatiles, notably methane, that increase greenhouse gas emissions. Catalytic sites confined at the bottom of mesoporous wells, under conditions in which the pore exerts the greatest influence over the mechanism, are capable of producing less gases than unconfined sites. A new architecture was designed to emphasize this pore effect, with the active platinum nanoparticles embedded between linear, hexagonal mesoporous silica and gyroidal cubic MCM-48 silica (mSiO2/Pt/MCM-48). This catalyst deconstructs polyolefins selectively into ∼C20–C40 paraffins and cleaves C–C bonds at a rate (TOF = 4.2 ± 0.3 s–1) exceeding that of materials lacking these combined features while generating negligible volatile side products including methane. The time-independent product distribution is consistent with a processive mechanism for polymer deconstruction. In contrast to time- and polymer length-dependent products obtained from non-porous catalysts, mSiO2/Pt/MCM-48 yields a C28-centered Gaussian distribution of waxy hydrocarbons from polyolefins of varying molecular weight, composition, and physical properties, including low-density polyethylene, isotactic polypropylene, ultrahigh-molecular-weight polyethylene, and mixtures of multiple, post-industrial polyolefins. Coarse-grained simulation reveals that the porous-core architecture enables the paraffins to diffuse away from the active platinum site, preventing secondary reactions that produce gases.

show abstract

Section: ■ Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Two Mesoporous Domains Are Better Than One for Catalytic Deconstruction of Polyolefins

Tennakoon,

Wu,

Meirow

et al. 2023

J. Am. Chem. Soc.

View full text Add to dashboard Cite

show abstract

Treasuring trash: Pt/SrTiO3 catalysts process plastic waste into high-value materials

Peczak

Kennedy²,

Hackler³

et al. 2023

Matter

View full text Add to dashboard Cite

Catalytic Upcycling of Polyolefins

Sun,

Dong,

Gao

et al. 2024

Chem. Rev.

View full text Add to dashboard Cite

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

show abstract

Population balance models for polymer upcycling: signatures of the mechanism in the molecular weight evolution

Abstract: Chemical and catalytic upcycling processes could help realize a circular plastics economy, but current models for testing mechanistic hypotheses and designing catalysts remain primitive. This work shows how proposed catalytic...

Cited by 9 publications

References 91 publications

Two Mesoporous Domains Are Better Than One for Catalytic Deconstruction of Polyolefins

Two Mesoporous Domains Are Better Than One for Catalytic Deconstruction of Polyolefins

Treasuring trash: Pt/SrTiO3 catalysts process plastic waste into high-value materials

Catalytic Upcycling of Polyolefins

Contact Info

Product

Resources

About