Pyrolysis mechanism of R601a/R245fa mixture: A ReaxFF-MD and DFT study

Liu, Wei; Yu, Wei; Duan, Jizhou; Shen, Anwei

doi:10.1016/j.comptc.2023.114244

Cited by 7 publications

(2 citation statements)

References 23 publications

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“…In the wake of advancements in computer and simulation technology, the exploration of the pyrolytic reaction of phenolic resins at the molecular level has garnered considerable interest. ReaxFF molecular dynamics (ReaxFF MD) is an innovative simulation method that tracks or detects the free radicals formed during the chemical reaction. − By examining these free radicals, intermediates, and products, the pyrolysis mechanism can be elucidated, providing explanations for experimental observations that are otherwise challenging to interpret . Xing et al investigated the thermal decomposition of nine phenol-formaldehyde resin models with different structures using ReaxFF molecular dynamics simulations, analyzing the effects of substituent positions of the methylene bridge on the benzene ring and temperature on the pyrolysis mechanism of the phenolic resin.…”

Section: Introductionmentioning

confidence: 99%

New Insights into Phenolic Resin Decomposition under Oxidative Conditions of High Temperature

Huang,

Zhao,

Cai

et al. 2024

Ind. Eng. Chem. Res.

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Phenol-formaldehyde (PF) resin, a significant synthetic thermosetting polymer, is extensively utilized across diverse engineering domains. The exploration of the high-temperature oxidation mechanism of PF resin is pivotal to enhancing its thermal stability. However, current research lacks a comprehensive study on the pyrolysis mechanism of PF resin under different oxidizing conditions. Herein, this work systematically explores the pyrolysis mechanism of PF resin under various hightemperature oxidation environments by using pyrolysis experiments and molecular dynamics simulations. The high-temperature oxidative cracking experiment revealed that the major liquid products from phenolic resin are single-ring aromatic compounds, such as phenol, benzene, and cresol. As the temperature increases, the proportion of phenol increases while that of m-cresol decreases. The Kissinger method determined the activation energies and mechanisms of the four-step oxidation reactions. ReaxFF simulations validate that the erosion products and mechanisms of oxygen on PF are consistent with the experiment and further explore the bombardment effects of different highenergy oxygen. It was found that oxygen caused greater damage to the resin than atomic oxygen by breaking bonds, such as C−H and C�C, producing a richer array of products. This study elucidates the reaction mechanisms of gaseous byproducts, including H 2 , OH, C 2 H 2 , and CO 2 , which are released during the oxygen bombardment process on phenolic resin. These findings offer new insight into the high-temperature pyrolysis of resin under extreme oxidative conditions and enrich our understanding of the complex interactions between material properties and environmental factors.

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Section: Introductionmentioning

confidence: 99%

New Insights into Phenolic Resin Decomposition under Oxidative Conditions of High Temperature

Huang,

Zhao,

Cai

et al. 2024

Ind. Eng. Chem. Res.

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“…ReaxFF, based on bond order theory, can dynamically simulate chemical bond breaking and formation, enabling more reactive simulations of large systems compared to traditional empirical force fields. , By fitting to quantum mechanics methods using a training set of ab initio data, ReaxFF overcomes the size and cost limitations of calculations to provide reliable predictions of rate constants, activation barriers, and reaction mechanisms for a wide range of systems . Consequently, with a balance of accuracy and efficiency compared to empirical force fields and QM, ReaxFF has been widely applied to simulate combustion and phenolic pyrolysis of large molecular systems. − For instance, pyrolysis simulation of resin systems involves modeling complex chemistry with bond dissociation and recombination to generate various small molecule products . However, ReaxFF fails to capture phenolic intermediates during resin pyrolysis and match the experimentally observed low resin decomposition temperature of 800 K. In fact, most ReaxFF combustion pyrolysis simulations use temperatures around 3000 K, which are significantly higher than industrial and experimental conditions of 500–1500 K. − These elevated temperatures accelerate kinetic rates, resulting in simulated values that exceed experimental ones and hinder intermediate observation .…”

Section: Introductionmentioning

confidence: 99%

Adaptive Force Field Parameter Optimization for Expanding Reaction Simulations within Wide-Ranged Temperature

Huang,

Li,

Wang

et al. 2024

J. Phys. Chem. A

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Large-scale and long-term simulation of chemical reactions are key research topics in computational chemistry. However, there are still difficulties in simulating high-temperature reactions, such as polymer thermal decomposition. Herein, we introduce an adaptive potential parameter optimization framework designed to automatically fine-tune parameters, and the application of it to optimize ReaxFF parameters enhances the accuracy of chemical reaction simulations conducted at experimental temperatures. To achieve this, we leverage the power of Random Forests and interpretable machine learning techniques that enable the identification and selection of parameters that exert a substantial influence on the target attribute. By training deep neural network (NN) models, we established optimized parameter associations with reference properties. We train deep neural network (NN) models to establish the relationship between the optimized parameters and reference properties. We employ a Genetic Algorithm (GA) to utilize the surrogate NN model and the quantum mechanical targets to speed up the search for the optimal parameters. Our simulation results of resin pyrolysis show that the adaptive optimized ReaxFF can predict the peak temperature more accurately and obtain reasonable product composition under conditions that more closely resemble experimental scenarios. This work facilitates advances in force field parameter optimization for more accurate and universal reaction simulations.

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Comparison of combustion and interaction mechanisms of mixed working fluids R152a and R1270: A theoretical and experimental study

Zhang,

He,

Hua

et al. 2024

Energy

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Pyrolysis mechanism of R601a/R245fa mixture: A ReaxFF-MD and DFT study

Cited by 7 publications

References 23 publications

New Insights into Phenolic Resin Decomposition under Oxidative Conditions of High Temperature

New Insights into Phenolic Resin Decomposition under Oxidative Conditions of High Temperature

Adaptive Force Field Parameter Optimization for Expanding Reaction Simulations within Wide-Ranged Temperature

Comparison of combustion and interaction mechanisms of mixed working fluids R152a and R1270: A theoretical and experimental study

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