Thermal degradation of virgin and waste plastics: Estimation of kinetic and thermodynamic parameters using model‐free iso‐conversional methods

Singh, Rohit Kumar; Gupta, Prithviraj; Ruj, Biswajit; Sadhukhan, Anup Kumar; Gupta, Parthapratim

doi:10.1002/kin.21692

Cited by 7 publications

(1 citation statement)

References 68 publications

(284 reference statements)

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“…Polyethylenes differ in microstructure, and their pyrolysis must not yield the same products. − The pathways of thermolysis have been discussed in some detail, and over the years several models were evaluated on their merits. − The thermal degradation of linear polyethylene occurs overall as a “one-step” process with one peak in differential thermal gravimetric determinations. − It starts by a random chain scission (RS) to generate two primary alkyl radicals. ,, Ethylene results from β-scission in these radicals (a depolymerization a.k.a. unzipping, UZ).…”

Section: Introductionmentioning

confidence: 99%

Fast Pyrolysis Product Analysis of Commercial Polyethylenes

Matthiesen,

Plessing,

Luinstra

2024

Energy Fuels

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The pyrolysis of eight commercial polyethylene grades in a fluidized bed reactor (FBR, Hamburger Verfahren) operating at 750 °C (residence time of ∼3 s) is carried out to show that the gaseous and liquid product spectra are very similar. The reaction temperature is the sole parameter of major impact for the outcome of the pyrolysis in the FBR between 700 and 800 °C. The temperature of 750 °C gives a good yield of ethylene (31 wt %) and propylene (15 wt %) and moderate amounts of methane (11 wt %). Solid products (soots) are hardly formed. A stochastic analysis shows that the molar amounts of the linear alkane and alkene products with less than 4−5 carbon atoms (making up 75 wt % of the products) are confidently described by geometric distributions Geom(1 − α). The remaining 25 wt % of the products are mainly aromatics with 6 or more carbon atoms. The formation of alkanes at a 750 °C bed temperature is interpreted to result from random chain scission with a probability α of 0.82 in n-alkyls, followed by a hydrogen abstraction: 1-alkenes result from a competition between β-scission and 1,2-hydrogen shifts with an α of 0.64 for β-scission in linear alkyl radicals. The intermediate formation of n-alkyls and primary radicals is key; weak bond scissions (at branching points) are not relevant for polyethylene decomposition at 750 °C. The α geometric parameters are temperature dependent, giving access to activation energies of 47(4) kJ/mol for alkane formation and 54(2) kJ/mol for the difference in β-scission and 1,2-hydrogen shift on the interval between 600 and 900 °C. The geometric distributions suggest that the 75 wt % gaseous products are directly formed and transported away from the hot zone (surface ablation). The same analysis applied to published data on polyethylene pyrolysis shows that different geometric distributions for alkanes and alkenes are present too.

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Section: Introductionmentioning

confidence: 99%

Fast Pyrolysis Product Analysis of Commercial Polyethylenes

Matthiesen,

Plessing,

Luinstra

2024

Energy Fuels

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Insights into the oxidative thermal stability of mesoporous triazine‐based organic polymers: Kinetics and thermodynamic parameters

Altarawneh

2024

Int J of Chemical Kinetics

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This study investigates the thermal degradation kinetics of mesoporous triazine‐based polymers, namely triazine‐amine and triazine‐ether polymers. The synthesis, physicochemical characterization, and catalytic applications of these polymers were discussed in our previous report. Herein, the thermal stability parameters, including kinetic triplets and thermodynamic parameters, were determined using thermogravimetric analysis (TGA) and non‐isothermal mathematical approximations such as Coats‐Redfern, Broido, and Horowitz–Metzger methods. Triazine‐ether polymers exhibit thermal stability within the range of 200°C–300°C, while triazine‐amine polymer demonstrates superior thermal stability, reaching up to 450°C. According to the Coats‐Redfern method, the degradation follows reaction orders of 0.5 ≤ n ≤ 1. The activation energy of triazine‐amine polymer is notably high, particularly at the third degradation stage (e.g., 89.0 kJ/mol by the Broido method), attributed to its high nitrogen content. Conversely, the higher carbon content of triazine‐ether polymers reduces their activation energy to approximately 30 kJ/mol at all stages and thus, facilitates the degradation process. Thermodynamically, the degradation process is favorable yet non‐spontaneous, with intermediate states of the polymers exhibiting higher entropy, indicative of their enhanced degradation capability.

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Combustion characteristics and thermal degradation kinetics of microporous triazine-based organic polymers: the role of organic linkers

Altarawneh

2024

Polym. Bull.

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Thermal degradation of virgin and waste plastics: Estimation of kinetic and thermodynamic parameters using model‐free iso‐conversional methods

Cited by 7 publications

References 68 publications

Fast Pyrolysis Product Analysis of Commercial Polyethylenes

Fast Pyrolysis Product Analysis of Commercial Polyethylenes

Insights into the oxidative thermal stability of mesoporous triazine‐based organic polymers: Kinetics and thermodynamic parameters

Combustion characteristics and thermal degradation kinetics of microporous triazine-based organic polymers: the role of organic linkers

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