Comparison of literature models for volatile product formation from the pyrolysis of polyisobutylene at mild conditions: Data analysis, free-radical mechanistic considerations, and simulation of initial product-forming pathways

Poutsma, Marvin L.

doi:10.1016/j.jaap.2005.02.009

Cited by 11 publications

(4 citation statements)

References 171 publications

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“…In fact, Poutsma [8] demonstrated that the absence of a rigorous analytical methodology and of reaction regime control could lead to contradicting mechanistic interpretations. Similar inconsistencies have also been reported elsewhere for polyisobutylene [9], polystyrene (PS) [8] and biomass [10,11]. Such contradictions have obvious implications for technological progress in terms of reactor design.…”

Section: Introductionsupporting

confidence: 68%

Structure-reactivity relationship in pyrolysis of plastics: A comparison with natural polymers

Larraín

Carrier

Radović

2017

Journal of Analytical and Applied Pyrolysis

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Highlights• Global activation energy depends on conversion in pyrolysis of all polymers.• Activation energy variability is proportional to chemical complexity of polymers.• An Evans-Polanyi relationship for initiation reactions of polymer pyrolysis is proposed. AbstractRecent advances in plastics recycling confirm the high potential of pyrolysis technologies to enhance recovery and selectivity rates. Modelling the kinetics of this complex process to stimulate scaling-up opportunities remains a major challenge.This study is an attempt to develop practical quantitative reactivity indices for the pyrolysis of natural and synthetic polymers. Representative samples from both categories (coal and pine vs. PET, PE and PMMA) were selected. Their weight loss during pyrolysis was determined experimentally and analyzed using judicious lumping procedures for its initiation, propagation and termination steps. The combined experimental and theoretical approach allowed us to determine apparent activation energies using the isoconversional Friedman method; and the use of Benson's group contribution method generated reaction enthalpies for the initiation reactions. Increasing activation energies with conversion in each case indicated that bond scission proceeds in order of increasing bond strength. The greater chemical complexity of natural polymers was reflected in the higher coefficients of variability for activation energy and wider ranges of reaction enthalpies. A structure-reactivity relationship based on the Evans-Polanyi theory was used to test the hypothesis that primary pyrolysis kinetics is controlled by cleavage of weakest chemical bonds. While the results show that this approach is promising, especially if confirmed by extension to a larger data set, they also suggest the need to compare the relative kinetic importance of initiation and propagation steps in the sequence of polymer pyrolysis reactions.

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Section: Introductionsupporting

confidence: 68%

Structure-reactivity relationship in pyrolysis of plastics: A comparison with natural polymers

Larraín

Carrier

Radović

2017

Journal of Analytical and Applied Pyrolysis

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“…18 We will extend the use of the carbocycle model from the (p f p) class to other reaction classes and compare predictions with the data base. We have recently suggested, 19 based on simple molecular mechanics simulations applied to the carbocycle model, that the presence of spectator alkyl substituents may accelerate 1,x-shifts for the (p f p) class, but that steric congestion at sec or tert reaction sites may decelerate 1,x-shifts. We will explore such predictions further and also compare them with the database.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Kinetic Data for Intramolecular 1,x-Hydrogen Shifts in Alkyl Radicals and Structure/Reactivity Predictions from the Carbocyclic Model for the Transition State

Poutsma

2006

J. Org. Chem.

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Experimental and computational kinetic data for the intramolecular 1,x-hydrogen shift in alkyl radicals are compiled in Arrhenius format for x = 2-5. Significant experimental disparity remains, especially for x = 2 and 3. Experimental data for radicals with tert centers or bearing spectator substituents are lacking for all x, and none exist for x = 6. The common use of the strain energy of the unsubstituted (x+1)-carbocycle to coarsely model the activation energy for the 1,x-shift is extended to explore more subtle differences in progressively methyl-substituted systems by use of molecular mechanics estimates of differences in strain between radicals and carbocycles. For x = 5 and 6, a sterically driven increase in E is predicted for shifts in the tert --> tert class that apparently runs counter to the behavior of bimolecular hydrogen transfers. In contrast, a sterically driven decrease in E is predicted to result from spectator methyl groups for the prim --> prim reaction class for all x. There is no experimental basis to test these predictions; fragmentary computational evidence lends some support to the second but is ambiguous concerning the first. Possible deficiencies in the use of carbocycles as transition state models are discussed.

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“…The reaction mechanism of polymerization passes four stages during the plastic degradation process: initiation, propagation, hydrogen transfer, and termination reactions. Through the initiation reaction process, there are three types of cracking or reforming processes: random, end chain, and chain strip cracking (Bockhorn et al, 1999;Faravelli et al, 1999Faravelli et al, , 2003Kruse et al, 2001Kruse et al, , 2002Kruse et al, , 2003Kruse et al, , 2005Broadbelt, 2008, 2009;Marongiu et al, 2003Marongiu et al, , 2007Poutsma, 2003Poutsma, , 2005Poutsma, , 2009Westerhout et al, 1997a,b) They are determined by the side functional group on the plastic molecular carbon backbone. Then, there are propagation reactions, especially β-scission, (Vinu and Broadbelt, 2012b) which is the cracking of large molecular weight.…”

Section: Figure (4) Schematic Illustrating the Complex Formationmentioning

confidence: 99%

Studying and Evaluating Sustainable Materials for Converting Plastic Waste to Fuel

Abdelrahman¹,

Dosky²,

Mohamed³

et al. 2018

EER

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Gasification is one of the most important solutions for plastic waste management. We researched the conversion of plastic waste to fuel using sustainable material (Nano Clay) modified with Nano transition metals (TiO 2 , MnO, and ZnO). This was processed in a fix bed reactor design. After studying the reaction mechanism of the gasification process, we evaluated the optimize (reactor temperature, reaction time and feeding ratio of the modified catalyst) on the gasification process with its application for the modified catalyst on the degradation of polyethylene high density(PEHD), other waste plastic to fuel (CH 4 , H 2 , and other light component gasses). This method can be used as an important resource for renewable energy (like generating electricity and clean fuel), rather than waste for landfills and the incineration process which is the main source of CO 2 emissions.

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Comparison of literature models for volatile product formation from the pyrolysis of polyisobutylene at mild conditions: Data analysis, free-radical mechanistic considerations, and simulation of initial product-forming pathways

Cited by 11 publications

References 171 publications

Structure-reactivity relationship in pyrolysis of plastics: A comparison with natural polymers

Structure-reactivity relationship in pyrolysis of plastics: A comparison with natural polymers

Evaluation of the Kinetic Data for Intramolecular 1,x-Hydrogen Shifts in Alkyl Radicals and Structure/Reactivity Predictions from the Carbocyclic Model for the Transition State

Studying and Evaluating Sustainable Materials for Converting Plastic Waste to Fuel

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