Detailed Reaction Mechanism Research Articles

Preparation of lanthanide-doped polystyrene/CeO2 abrasives and investigation of slurry stability and photochemical mechanical polishing performance

With the pursuit of high efficiency and quality chemical mechanical polishing (CMP), exploring additional efficiency enhancement means based on the CMP has become a trend. Polystyrene/CeO2 core-shell abrasives (core: 85 nm, shell: 10 nm) doped with Lanthanide (La, Nd, and Eu) were synthesized by a modified in situ chemical precipitation method, promising application for photocatalytic-assisted CMP of silica wafer. The doping of La, Nd, and Eu can reduce the band gap of CeO2 from 3.24 eV to 3.23 eV, 3.20 eV, and 3.22 eV, respectively, indicating enhanced photocatalytic activity. Especially for Nd-doped abrasives, the content of Ce3+ increases from 0.49 to 0.56, accompanied by the generation of oxygen vacancies, as proved by X-ray photoelectron spectroscopy (XPS) and Raman spectra. In addition, the prepared polishing slurry could remain stable for up to 7 days by the steric hindrance effect and electrostatic repulsion of the dispersants. The materials removal rate of Nd-doped abrasive in photocatalytic-assisted CMP of SiO2 films reaches 174.3 ± 7.6 nm/min, which is 163% higher than those in CMP, while the surface roughness (Ra) in localized areas (2×2 µm2) can be reduced from the initial 0.82 ± 0.01 nm to 0.36 ± 0.05 nm. Detailed reaction and removal mechanism involved in photocatalytic-assisted CMP processes is discussed.

Numerical simulation of flow field and residence time of nanoparticles in a 1000-ton industrial multi-jet combustion reactor

In this work, by establishing a three-dimensional physical model of a 1000-ton industrial multi-jet combustion reactor, a hexahedral structured grid was used to discretize the model. Combined with realizable k–ε model, eddy-dissipation-concept, discrete-ordinate radiation model, hydrogen 19-step detailed reaction mechanism, air age user-defined-function, velocity field, temperature field, concentration field and gas arrival time in the reactor were numerically simulated. The Euler–Lagrange method combined with the discrete-phase-model was used to reveal the flow characteristics of particles in the reactor, and based on this, the effects of the reactor aspect ratios, central jet gas velocity and particle size on the flow field characteristics and particle back-mixing degree in the reactor were investigated. The results show that with the decrease of aspect ratio in the combustion reactors, the velocity and temperature attenuation in the reactor are intensified, the vortex phenomenon is aggravated, and the residence time distribution of nanoparticles is more dispersed. With the increase in the central jet gas velocities in reactors, the vortex lengthens along the axis, the turbulence intensity increases, and the residence time of particles decreases. The back-mixing degree and residence time of particles in the reactor also decrease with the increase in particle size. The simulation results can provide reference for the structural regulation of nanoparticles and the structural design of combustion reactor in the process of gas combustion synthesis.

Study on the Influencing Factors of Modal Transformation of Continuous Rotating Detonation Wave Propagation

In order to study the propagation mode of rotating detonation wave, the detailed reaction mechanism of hydrogen-oxygen with 9 components and 19 steps is used, and the finite rate chemical reaction model is used for numerical calculation. After ignition, there is a stable collision period in the flow field for a certain period, and the collision extinguishing and new detonation wave generation occur during the mode conversion. By adding nitrogen or argon to the hydrogen-oxygen mixture for dilution, when the dilution ratio increases, the activity of the gas mixture decreases, the height of the combustible gas layer increases, and the temperature of the combustion product after the detonation wave decreases away from the head of the detonation wave, which will reduce the mixture that is burned in advance. There are different degrees of reflected shock at the outlet of the combustion chamber, and the upward detonation wave will cause the height change of the detonation wave head and the instability of the flow.

Recent advances in low-gradient combustion modelling of hydrogen fuel blends

Low-gradient combustion (LGC) proved to be an effective alternative technology to reduce pollutant emissions and carbon footprint, specifically when combined with hydrogen as a fuel or blend component. This novel technology offers several advantages over conventional combustion regimes, including a more effective control of emissions and providing greater flexibility in fuel application. The impact of hydrogen on this regime is still not well-known, especially when it comes to the combustion of pure hydrogen and fuels with a high hydrogen content. In the last two decades, numerical simulations have become a powerful tool that facilitates the research and design of LGC, particularly in terms of stability of the process and the emission of pollutants. This article provides an up-to-date review of recent trends and theoretical knowledge in low-gradient combustion. This includes the guidelines and recommendations applied to LGC modelling. Comparisons have been made between the recently published modelling approaches presented by the authors, including a detailed assessment of the discrepancies in the temperature predictions. The challenges and limitations associated with the LGC combustion modelling of conventional fuels (i.e., natural gas, methane, syngas) blended with hydrogen are also discussed. The review demonstrated that the Eddy Dissipation Concept (EDC) is the most common turbulent-chemical interaction model employed in LGC combustion simulations. The performance of the EDC can be significantly improved by variable constants Cγ and Cτ based on local turbulent Reynolds and Damköhler numbers. However, the most recent publications indicate that the flamelet-based approach can be considered as a promising (and more cost-effective) alternative to the EDC. Furthermore, the chemical kinetic studies considered in this review confirm that there is no detailed reaction mechanism capable of accurately predicting the temperature profile along with the emissions of the main species of interest, i.e., NOx, CO, CO2, and OH. Although GRI-Mech 2.11 is the most widely used mechanism in LGC simulations, providing satisfactory overall accuracy.

Ignition studies of hydrogen-air mixtures over hot wire

Hot surface ignition of combustible gas mixtures poses a safety threat in many engineering applications. Gaseous mixtures ignite when hot surface temperature reaches the ignition threshold. In the present work, two-dimensional numerical simulations with detailed reaction mechanism are performed to simulate the flow of stoichiometric hydrogen-air mixture over a stationary hot wire. The effect of heating rates, wire diameters, mixture inlet velocities, and mixture equivalence ratios on the ignition threshold is investigated. In all the cases investigated, ignition is found to occur at the rear stagnation point, and wire heating rate did not influence the ignition phenomenon significantly. With an increase in mixture inlet velocity and mixture equivalence ratio, the ignition threshold increases, whereas the threshold has been found to decrease with increasing wire diameters. The role of the local equivalence ratios at the ignition point and reaction rates prior to the ignition process has been studied to help better understand the ignition phenomenon under different conditions.

Nanoclay Modulates Cation Occupancy in Manganese Ferrite for Catalytic Antibacterial Treatment.

Controllable preparation is the current frontier in the field of inorganic nanomaterial-based artificial enzymes (nanozymes). For ferrites, the factors affecting cation occupancy are very complex, making the modulation of cation occupancy extremely challenging. Herein, we report a new strategy to modulate the cation occupancy of manganese ferrite (MFO) based on the structural properties of nanoclay (i.e., montmorillonite K10). It demonstrates that montmorillonite K10 mainly changes the valence state and occupancy of manganese ions in manganese ferrite and not iron ions. K10 increases the proportion of Mn (II) in manganese ferrite and causes more manganese ions to migrate to the tetrahedral sites. As expected, the prepared new inorganic compound possesses excellent enzyme-like catalytic activities and antibacterial functional properties, which are attributed to Mn (II) accelerating Fe (III) reduction and hydroxyl radical formation. Furthermore, steady-state kinetic assays are used to study the reaction mechanism in detail. In vitro and in vivo antibacterial experiments show that the synthesized inorganic compounds exhibit satisfactory disinfection and wound skin recovery efficiencies. This work emphasizes the controllable preparation of new inorganic compounds with biomimetic activity and provides novel insight into the biological effects of inorganic nanomaterials.

Automatically generated detailed and lumped reaction mechanisms for low- and high-temperature oxidation of alkanes

In this work, we present a methodology on automatic generation of predictive lumped sub-mechanisms for normal and branched alkanes. This methodology aims at obtaining lumped reaction mechanisms that preserve the chemical behavior of each reaction class in the detailed model. To achieve this goal, detailed sub-mechanisms for combustion of alkanes are generated by employing an updated version of the MAMOX++ software developed in this work; recent progress in the low-temperature reaction classes and rate rules are incorporated into the updated software. Instead of computing the selectivities of several primary products with MAMOX++ and fitting the selectivities between the detailed and lumped models, this work proposes a new methodology to generate the lumped sub-mechanisms for fuel molecules. The stoichiometric parameters and the reaction rates for each reaction class in the lumped sub-mechanism are fitted to match those in the detailed model. Based on the present methodology, both the detailed and lumped sub-mechanisms for normal C5C10 alkanes and branched C5C8 alkanes, that is for 15 different fuels, are automatically generated and merged into a base chemistry model (i.e. AramcoMech 2.0), respectively. The detailed and lumped models are validated against the experimental data in the literature. The automatically generated detailed models for alkanes are able to capture the experimental targets across a wide range of conditions, demonstrating the robustness of the reaction classes and rate rules adopted. The lumped models for normal alkanes have similar performance to their respective detailed models, and are able to predict the oxidation behavior of normal alkanes. However, prediction deviations between the detailed and lumped models for branched alkanes are shown to be slightly greater.

A comprehensive kinetic modeling of oxymethylene ethers (OMEn, n=1–3) oxidation - laminar flame speed and ignition delay time measurements

This work reports on the development and experimental validation of a detailed reaction mechanism for the oxidation of polyoxymethylene dimethyl ethers (OMEn, n = 1–3). The validation is done by constant-volume chamber laminar flame speeds (393 K and 443 K, 1 to 5 bar, and equivalence ratio 0.8 to 1.6) and Rapid Compression Machine ignition delay times (550–680 K, 10 and 15 bar, equivalence ratios of 0.5–2.0) in OMEn/air mixtures. Using our new experimental and published data, the validation basis for the new kinetic model comprises the pyrolysis and oxidation of OMEn (n = 1–3) in freely propagating flames, auto-ignition in rapid compression machines and shock tubes, and speciation in jet-stirred and flow reactors as well as burner-stabilized premixed flames. The model provides a reasonable agreement with the experimental data for a broad range of conditions investigated. The performance of the developed model is compared against the recent literature models. OMEn (n = 1–3) all have the same laminar flame speed. The model suggests that the chemistry of OME0 (DME) and CH3OCHO (methyl formate) is the one that dictates the flame chemistry. Under the same pressure and equivalence ratio conditions, ignition delay times of OME2 and OME3 are similar for the investigated temperature range. This work helps to improve the understanding of OMEs chemistry. The model developed in this work will serve as the base mechanism for higher chain length OMEs (n>3).

The capture of carbonyl sulfide by N‐methyldiethanolamine: A systematic density functional theory investigation

AbstractIn this contribution, the mechanism of carbonyl sulfide (COS) absorption by N‐methyldiethanolamine (MDEA) aqueous solution was explored via theoretical computations. Detailed reaction mechanisms were analyzed using density functional theory (DFT) calculations at the B3LYP‐D3 level of theory. In total, four different pathways for COS absorption by MDEA have been considered. The most favorable pathway for the removal of COS is a three‐step mechanism including the hydrolysis, proton transfer, and dissociation of CO2, and hydrolysis is the rate‐determining step. The mechanisms of the COS absorption by different amines were investigated, and the calculated results suggest that the total energy barrier for the COS absorption by MDEA is comparable to that by monoethanolamine (MEA), diethanolamine (DEA), and diisopropylamine (DIPA), indicating the COS absorption by all the four amines are feasible, while MDEA gives a better performance in terms of thermodynamics.

Burner stabilized flames: Towards reliable experiments and modelling of transient combustion

In this work the diffusive–thermal pulsations of the burner stabilized methane-air flames are investigated experimentally, by analysing the OH∗ chemiluminescence signal, and numerically within the model with various detailed reaction mechanisms. The employment of the nitrogen co-flow configuration to isolate the flame from the surrounding air allows us to obtain the experimental data of high fidelity such that the difference between the numerical data calculated with different reaction mechanisms is greater then the experimental uncertainty, demonstrating that the proposed technique can be used to verify the reaction mechanisms. Sensitivity analyses are carried out and it is shown that the steady and pulsating regimes of combustion has different although partly overlapping subsets of most important elementary reactions, especially for the case of relaxational oscillations in which the combustion front exhibits stages close to quenching and re-ignition. The suggested configuration can thus be used to access “transient combustion” and to gain an additional information to verify mechanisms.

Investigation on the Reaction Mechanism of Methane Oxidation over MgAl2O4‐Supported Single‐Atom Catalyst Prepared at High Temperature

AbstractStability and reactivity of single‐atom catalysts (SACs) are the points of concern in catalysis, especially under the harsh conditions, such as at elevated temperatures in oxidizing conditions. Previous work showed that thermally stable Pt1 SAC supported on K‐modified MgAl2O4 prepared by a vapor‐phase self‐assembly mechanism (Pt1/K/MgAl2O4) showed better performance than a Pt/MgAl2O4 nanocatalyst in catalytic CH4 oxidation (Chem, 2022, 8, 731–748). However, the detailed reaction mechanism remains unclear, which preventing the further development of single‐atom catalysts for CH4 oxidation. Herein, the sintering resistance behaviour of the Pt1/K/MgAl2O4 catalyst, was investigated by means of density functional theory (DFT) calculations, and it was found that the catalytic CH4 oxidation takes place via the Mars‐van Krevelen (MvK) mechanism, similar to that on conventional oxides. This viewpoint is further verified by experiments. Additionally, other noble metals (Au, Ir and Ru) and alkali elements (Na and Cs) are also investigated and it is found that the alkali types also affect the catalytic performance. This work clarifies the reaction mechanism of CH4 oxidation on metal SAC supported on MgAl2O4 synthesized at high temperature, providing a chance to manipulate the performances of metal SAC in CH4 oxidation.

Kinetically consistent detailed surface reaction mechanism for steam reforming of methane over nickel catalyst

A one-dimensional model, LOGEcat is used to develop a detailed surface reaction mechanism for modeling the steam reforming of methane over a nickel-based catalyst. The focus of the paper is to develop a kinetically consistent surface reaction mechanism. The two terms, kinetically and thermodynamically consistent mechanisms, will be used frequently in this article. Note that when the mechanism is thermodynamically consistent then the thermodynamic data or the thermochemistry of the species is not used and all the reactions in the mechanism are forward reactions (no backward reactions included) which need the Arrhenius parameters (pre-exponential factor, A_{r}; activation energy, E_{r}; temperature exponent, beta _r) explicitly for each reaction. The kinetically consistent mechanisms need Arrhenius parameters only for the forward reactions and does not need these parameters for backward reactions making the backward reactions independent of the kinetics. The rate for the backward reactions is calculated with the help of thermochemistry of the intermediate species involved in the reaction mechanism. Since the thermochemistry of the intermediate species are not easily available, this makes such studies much more complex. The original multi-step reaction mechanism consists of 42 reactions which are thermodynamically consistent. In this study we have modified this reaction mechanism from literature and used only 21 (reversible) direct reactions. This aspect is important because by using only 21 reactions, we use the thermochemistry of the species to achieve thermodynamic equilibrium instead of providing the Arrhenius parameters for forward and backward reactions. We use the same A_{r}, E_{r} and beta _r values as used in the reference paper for the considered 21 reactions which are in equilibrium. However, the value of A_{r}, E_{r} and beta _r for the inverse/backward reactions are not given in the mechanism and the reverse rates are calculated by using the equilibrium and forward rate. Therefore, a sensitivity analysis on thermochemistry of the species is performed for a better agreement with the literature data. The method is presented for ensuring kinetic consistency and bringing thermochemistry of species in play while developing a surface reaction mechanism. The applicability of the mechanism is tested for two different simulation set-ups available in literature considering various reactor conditions in terms of parameters given as temperature and steam-to-carbon (S/C) ratio. Several chemical reaction terms, such as, selectivity, conversion and mathrm {H_2}/{text{CO}} ratio are shown for different parameters in comparison with the available reference data. The detailed mechanism developed in this study is able to accurately express the steam reforming of methane over the nickel catalyst for complete ranges of temperature for both the set-ups and within acceptable limit for S/C ratio considered for the analysis.

Enhancing oxygen reduction reaction activity of pyrolyzed Fe–N–C catalyst by the inclusion of BN dopant at the graphitic edges

We study the detailed mechanism of oxygen reduction reaction (ORR) at the graphitic edges of BN-doped pyrolyzed Fe–N–C catalyst (FeN4-BN-edge) by utilizing the combination of DFT and microkinetic calculations. We find that the ORR mechanism on FeN4-BN-edge active sites is more selective toward the associative reduction pathway for all relevant potential ranges instead of the dissociative reduction pathway. This situation arises because the O2 dissociation energies on the FeN4-BN-edge active sites are too high for the dissociative reduction pathway to take place with sufficient ORR rates. The inclusion of BN-dopant at the graphitic edge of pyrolyzed Fe–N–C is found to improve the ORR activity of the catalyst. One factor contributed to this improvement originates from the easy formation of active site configurations at the graphitic edges, which is induced by the interaction between neighboring FeN4 and BN configurations. Another factor is the formation of the FeN4-BN configuration at the zigzag edge of graphene. These active sites could improve the onset potential for the associative reduction pathway up to 0.12 V larger than that at the standard FeN4 active site in the basal plane of graphene.

Transition-Metal-Catalyzed Remote C–H Bond Functionalization of Cyclic Amines

AbstractC–H bond functionalization is one of the most effective strategies for the rapid synthesis of cyclic amines containing substituents on the ring, which are core structures of many bioactive molecules. However, it is much more challenging to perform this strategy on remote C–H bonds compared to the α-C–H bonds of cyclic amines. This graphical review aims to provide a concise overview on transition-metal-catalyzed methods for the remote C–H bond functionalization of cyclic amines. Examples are categorized and demonstrated according to mechanistic pathways that initiate the reactions of cyclic amine substrates. Where relevant, selected substrate scope and detailed reaction mechanisms are given.

Mxene Ti3C2 generated TiO2 nanoparticles in situ and uniformly embedded in rGO sheets as high stable anodes for potassium ion batteries

Ti3C2/TiO2/rGO nanosheets were synthesized as anode materials for potassium ion batteries (KIBs) using modified Hummers, freeze drying, and thermal reduction in this paper. Layered Ti3C2 /TiO2/rGO nanosheets were synthesized by in-situ formation of rGO and TiO2 nanoparticles between Ti3C2 layers. As one of the most important members of MXenes family, Ti3C2 exhibits unique electronic characteristics, high specific surface area, strong electrical conductivity and chemically active surface, which can enhance electrode capacity. There are three ways to increase electrode conductivity and capacity: Firstly, rGO is applied as the substrate for the inlaying of TiO2 and Ti3C2 nanoparticles and nanosheets. Secondly, rGO may also buffer electrode volume changes during charging and discharging processes. In addition, the enormous surface area of rGO makes Ti3C2 and TiO2 nanoparticles dispersion well, and Ti3C2 and TiO2 nanoparticles can well separate rGO nanoparticles and prevent them from stacking up again. The synergistic effect of the three can efficiently relieve the stress and provide a rapid transport pathway between electrons and ions. The flake structure of Ti3C2/TiO2/rGO is advantageous to the stability of SEI film, which makes the material maintain good activity during charge and discharge process, and significantly increases its electrochemical performance. Therefore, Ti3C2/TiO2/rGO electrode has a high reversible capacity of 349.2 mAhg−1 after 200 cycles of 100 mAg−1 current, and a high stable capacity of 229.3 mAhg−1 after 500 cycles of 500 mAg−1 current, and has exceptional rate performance. The structure of Ti3C2/TiO2/rGO composite remains stable after 500 cycles, and no agglomeration occurs. The detailed reaction mechanism of Ti3C2/TiO2/rGO electrode as KIBs anode was analyzed by SEM, XRD, Raman, TGA, FT-IR, BET, TEM, XPS, EDS, CV, EX-situ XRD, ex-situ TEM, and so on. Therefore, it can be concluded that the Ti3C2/TiO2/rGO composite is an appropriate anode material for KIBs.

Numerical investigation of low-frequency instability and frequency shifting in a scramjet combustor

The combustion instability in a laboratory-scale direct-connect hydrogen-fueled scramjet combustor is investigated numerically. The numerical simulation has been carried out using a delayed detached eddy simulation (DDES) with a detailed reaction mechanism. The computational framework has high fidelity by applying multi-dimensional high order accurate schemes for handling convective and viscous fluxes. The field data were accumulated up to 100 milliseconds on each case to capture sufficiently the repetitive behavior of low-frequency instability of order of 100 Hz. The numerical results exhibit the formation/dissipation of pressure and shock wave induced by continuous heat release in the combustor. This motion of pressure/shock wave, so-called upstream-traveling shock wave, presents repeated dynamics between isolator and combustor with a period of several milliseconds. With this periodic hydrodynamic characteristic, the upstream-traveling shock wave interacts with the boundary layer and injected fuel stream affecting fuel/air mixing and burning, and finally inducing the combustion instability in a scramjet combustor. Frequency analysis derived major instability frequencies of 190 Hz and 450 Hz in the isolator and combustor for low and high equivalence ratios, respectively. Current numerical results present the underlying flow physics on the shifting of the instability frequency by changing the equivalence ratio observed by the previous experimental studies. The fact that an instability frequency exists homogeneously from isolator to combustor informs that the combustion instability of scramjet engine is the fully coupled flow/combustion dynamics throughout the engine on a macroscopic scale.

Solvent‐polarity‐dependent excited‐state behaviors for 2‐(2‐hydroxyphenyl) benzothiazole‐5‐(9H‐carbazol‐9‐yl)phenol fluorophore: A theoretical study

AbstractIn this work, we mainly focus on elaborating the effects of solvent polarity on excited state interactions and intramolecular proton transfer (ESIPT) behavior for the novel dye 2‐(2‐hydroxyphenyl) benzothiazole‐5‐(9H‐carbazol‐9‐yl)phenol (HBT‐Cz). Six aprotic solvents with different polarities are considered. Via comparing geometrical parameters, infrared (IR) vibrational spectra, and atomic charge distributions, we confirm that the hydrogen bond of HBT‐Cz is enhanced in S1 state. The enhancement of hydrogen bonding with low polarity is particularly important. Via exploring molecular orbitals, we find that intramolecular charge transfer happens and charge redistribution facilitates ESIPT reaction. Results show that low solvent polarity is more conducive to ESIPT process for HBT‐Cz. In order to clarify detailed reaction mechanism, we construct potential energy curves and determine that the ESIPT process of HBT‐Cz fluorophores could be controlled by solvent polarity. We not only elucidate the excited state behavior of HBT‐Cz systems but also present the polarity‐dependent ESIPT mechanism for HBT‐Cz fluorophore.

Self-reaction of C2H5O2 and its cross-reaction with HO2 studied with vacuum ultraviolet photoionization mass spectrometry

We present a study of the self-reaction of C2H5O2 and its cross-reaction with HO2 with VUV photoionization mass spectrometry. Hefei synchrotron radiation and a krypton discharge lamp are combined to ionize species. Key products including CH3CHO, C2H5OH, C2H5O and C2H5OOH formed from the reactions are directly observed and confirmed. In particular, the radical product C2H5O from the self-reaction is detected for the first time. The ionization energies of C2H5O and C2H5OOH are determined and the Franck-Condon factors are calculated to fit the photoionization spectra. Moreover, kinetic experiments are performed to confirm the products’ assignment and provide detailed reaction mechanism.

Modelling a detailed kinetic mechanism for electrocatalytic reduction of CO2

For the first time a fully-elementary reversible kinetic model for electrocatalytic CO2 reduction towards a multitude of different products has been established and verified with experimental data. The detailed reaction mechanism was generated by compiling hypothesized reaction paths and intermediates from many different sources. Thereby a focus was put on distinguishing different embodiments of similar elementary steps: For proton-coupled electron transfer three hydrogenation mechanisms were considered and for intermediates with unclear molecular structure separate paths were modelled. The micro-kinetic model was fed with tabulated energy parameters and results of DFT calculations to simulate CO2 reduction on a Cu(100) surface for constant applied potentials. The operating conditions were chosen according to published experimental results in order to compare Faradaic Efficiencies. With these, the model parameters were successfully calibrated across a wide potential range while keeping all values within a tight interval of theoretical bounds derived from ab initio calculations and other theoretical considerations. The calibrated model was found to be in good qualitative agreement with the measurement data and also captures trends of surface coverages reported for in-situ measurements. Most interestingly, it finds the widely accepted hypothesis of dimerization via *CO intermediates to be inaccurate. Instead, coupling reactions of *CHO and *CH2 intermediates are observed. The shifting of dimerization routes with varying applied potential especially towards ethylene is supported by other experimental studies. Furthermore, this work establishes a methodology of creating and calibrating complex electrochemical micro-kinetic models.

Temperature Effect on Formation of Polycyclic Aromatic Hydrocarbons in Acetylene Pyrolysis

AbstractThe detailed chemical reaction mechanism of high temperature pyrolysis is constructed through the comparison of various current reaction mechanisms and sub‐models. This mechanism can better predict the formation of polycyclic aromatic hydrocarbons. Through path analysis, the interrelationship of the growth mechanisms of polycyclic aromatic hydrocarbons is expounded. And the important contribution pathways of five‐membered/six‐membered rings at high temperatures are investigated. Through component flux analysis and sensitivity analysis, the results show that the main formation path of the external five‐membered ring is the acetylene addition of naphthalene. Its stability decreases with increasing temperature and is the main introduction route of molecular curvature during low temperature pyrolysis. However, the embedded five‐membered ring obtained by benzene cycloaddition is less affected by temperature and is the most important chemical reaction process introduced by high temperature molecular curvature. The hydrogen abstraction acetylene addition mechanism still plays a dominant role at different temperatures and is a classical pathway for the formation of six‐membered rings. By cooperating with multiple reaction mechanisms, the formation mechanism of polycyclic aromatic hydrocarbons at different temperatures can be well predicted.