Group Additivity Values Research Articles

Modeling the kinetics of hydrogen abstraction reactions in nitrogen-containing compounds via group additivity.

New group additivity values are presented to enable the modeling of a broad range of intermolecular hydrogen abstraction reactions involving nitrogen-containing compounds. From a dataset of 316 reaction rate coefficients calculated at the CBS-QB3 level of theory in the high-pressure limit, 76 group additivity values and 14 resonance corrections have been estimated. The influence of substituents on both the attacked hydrogen and attacking radical, being a carbon or nitrogen atom, has been investigated systematically. The new group additivity models can be applied to approximate the Arrhenius parameters of hydrogen abstraction reactions of nitrogen-containing compounds by hydrogen atoms, carbon-centered and nitrogen-centered radicals in the 300-1800 K temperature range. Complementary to the group additivity model, correlations for the tunneling coefficients, which depend on both the temperature and the activation energy of the reaction in the exothermic direction, have been generated. The good performance of the new group additivity schemes has been demonstrated using a test set of reactions. At 1000 K, the rate coefficients for all test set reactions are approximated on average within a factor of 1.45, 1.47 and 1.34, for the hydrogen abstractions with a reactive center of the type H-H-N, N-H-N and C-H-N respectively.

Modeling the thermochemistry of nitrogen-containing compounds via group additivity.

First-principles based kinetic modeling is essential to gain insight into the governing chemistry of nitrogen-containing compounds over a wide range of technologically important processes, e.g. pyrolysis, oxidation and combustion. It also enables the development of predictive, fundamental models key to improving understanding of the influence of nitrogen-containing compounds present as impurities or process additives, considering safety, operability and quality of the product streams. A prerequisite for the generation of detailed fundamental kinetic models is the availability of accurate thermodynamic properties. To address the scarcity of thermodynamic properties for nitrogen-containing compounds, a consistent set of 91 group additive values and three non-nearest-neighbor interactions has been determined from a dataset of CBS-QB3 calculations for 300 species, including 104 radicals. This dataset contains a wide range of nitrogen-containing functionalities, i.e. imine, nitrile, nitro, nitroso, nitrite, nitrate and azo functional groups. The group additivity model enables the approximation of the standard enthalpy of formation and standard entropy at 298 K as well as the standard heat capacities over a large temperature range, i.e. 300-1500 K. For a test set of 27 nitrogen-containing compounds, the group additivity model succeeds in approximating the ab initio calculated values for the standard enthalpy of formation with a MAD of 2.3 kJ mol-1. The MAD for the standard entropy and heat capacity is lower than 4 and 2 J mol-1 K-1, respectively. For a test set of 11 nitrogen-containing compounds, the MAD between experimental and group additivity approximated values for the standard enthalpy of formation amounts to 2.8 kJ mol-1.

Group additivity values for entropy and heat capacities of C2–C8 alkanes, alkyl hydroperoxides, and their radicals

Group additivity values for the thermodynamic properties of oxygenated radicals are poorly determined due to the absence of high quality reference data. Here, a set of 58 group additive values (GAV) for the standard entropy and heat capacity of relevance to alkane oxidation is derived from fits to an extensive and accurate database of standard entropies (298.15 K) and heat capacities (300–3000 K) recently calculated with the “STAR-1D” formalism. The 192 species in this database represent the alkanes (RH), alkyl radicals (Ṙ), alkyl hydroperoxides (RO2H), alkyl-peroxy (RȮ2) and hydroperoxy-alkyl (Q˙OOH) radicals for all of the isomers of C2–C5 alkane fuels and a select number of isomers of C6–C9 species. The STAR-1D thermochemical data for this set of species was previously obtained from a coupling of scaled B2PLYPD3/cc-pVTZ vibrational analyses with scaled ωB97X-D/cc-pVTZ one-dimensional hindered rotor corrections. The 2σ uncertainties in the GAV results relative to the STAR-1D data set are 2.4 cal K–1 mol–1 for the entropies and at most 2.0 cal K–1 mol–1 for the heat capacities in the temperature range 500–800 K. The 2σ fitting uncertainties in the heat capacity gradually reduce at higher temperatures reaching a value of 0.8 cal K–1 mol–1 at 2000 K decreasing to only 0.5 cal K–1 mol–1 at 3000 K. The high degree of accuracy for the GAV representations is obtained through the introduction of various new group terms, together with the re-optimization of existing group terms. Among the full set of 58 GAV terms, 25 include non-next-nearest neighbor interactions (NNI) and β-corrections. The updated GAVs can be applied in the prediction of entropies and heat capacities for a wide range of hydrocarbons and hydroperoxide species and their radicals, which is important to the accurate prediction of fuel reactivity at low-temperatures in the range 600–1000 K.

Ab Initio Group Additive Values for Thermodynamic Carbenium Ion Property Prediction

Carbenium ions are important intermediates in both zeolite and plasma chemistry. The construction of kinetic models for zeolite and plasma chemistry requires the incorporation of thermodynamic properties of these carbenium ions. In this way, thermodynamic equilibrium is incorporated resulting in more accurate and general kinetic models, which facilitate rational zeolite design and plasma process development. In this work, a consistent set of 46 group additive values (GAVs) and non-nearest neighbor interactions (NNIs) is determined for the standard enthalpy of formation, standard molar entropy, and heat capacity. The GAVs are regressed based on 165 quantum chemistry calculations with the CBS-QB3 composite method for carbenium ions as CBS-QB3 was proven a valid method for carbenium property prediction. The presented group additive approach gives the first GAVs and NNIs for entropy and heat capacity and 33 novel values for enthalpy prediction. The determined non-nearest neighbor interactions account for the effect of longer range hyperconjugation, resonance stabilization, and inductive stabilization, which are shown to be crucial for the carbenium stability. The presented group additivity scheme ensures an accurate prediction of all properties with a mean absolute error of 4.82 kJ/mol, 4.92 J/(mol·K), and 1.95 J/(mol·K) for the standard enthalpy of formation, standard molar entropy, and heat capacity, respectively. The reported GAVs and NNIs ensure the thermodynamic property prediction of paraffinic, olefinic, alkynic, aromatic, and five- and six-ring naphthenic cations.

Group additivity values for the heat of formation of C2–C8 alkanes, alkyl hydroperoxides, and their radicals

A set of 58 group additivity values (GAV) for the calculation of the heat of formation is derived from an extensive and accurate database of 192 ab initio heats of formation. The ab initio values are from companion calculations at the CCSD(T)–F12/cc-pVTZ-F12//B2PLYPD3/cc-pVTZ level of theory employing second order connectivity based hierarchy reference reactions with ANL energies for the reference species. This database of 192 species consists of alkanes (RH), alkyl radicals (Ṙ), alkyl hydroperoxides (RO2H), alkyl-peroxy (RȮ2) radicals, and hydroperoxy-alkyl (Q˙OOH) radicals of all of the isomers of C2–C5 alkane fuels and a select set of C6–C8 isomers. The GAV and ab initio based enthalpies for this dataset show excellent agreement, with an estimated 2σ uncertainty of 0.9 kcal mol–1. Among the 58 GAV terms, 40 are refinements of previously reported terms, while 18 are newly developed. These new GAV terms are mainly non-next-nearest neighbor interactions (NNI) and β-corrections. The inclusion of these new groups significantly improves the accuracy of the GAV estimates of the heats of formation. The updated GAVs can be used with increased confidence to estimate the heats of formation of combustion relevant hydrocarbons and oxygenated hydrocarbons and their corresponding radicals, which are important in predicting low-temperature chemistry and are critical in the development of accurate chemical kinetic models.

Computational thermochemistry of oxygenated polycyclic aromatic hydrocarbons and relevant radicals

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) have attracted growing attention due to their toxicological harmfulness and significant role in soot formation. This study comprehensively investigates the thermochemistry of OPAH species and relevant radicals via quantum-chemical calculations. Temperature-dependent enthalpy of formation, entropy, and heat capacity for C5C18 OPAHs (59 molecules and 33 radicals) are consistently determined at the M06–2X/6-311++G(d,p) level of theory. Considerable differences are found to be introduced by different methods when calculating electronic energies, and the G3 method outperforms the composite compound methods G3/G4/CBS-APNO. The calculated thermochemical properties from the G3 method show excellent agreement with literature data. An accurate thermochemistry database for OPAHs is thus developed. In addition, the existing group additivity (GA) method does not apply to OPAHs since the group additivity values (GAVs) derived from small hydrocarbons fail to predict large polycyclic species. Based on our dataset, GAVs are obtained from combinatorial considerations. The updated GAVs can be applied with enhanced confidence to estimate the thermochemical parameters at different temperatures for larger OPAHs where such high-accuracy quantum chemistry calculations are intractable. These thermodynamic properties and GAVs are crucial for the development of accurate kinetic models for OPAH formation chemistry and for achieving emission control.

The influence of thermochemistry on the reactivity of propane, the pentane isomers and n-heptane in the low temperature regime

The influence of thermochemistry on the reactivity of fuels at low temperatures (600–1000 K) is studied here. Specifically, the effect of different sets of thermochemistry on chemical model predictions is explored, where various sets are calculated at different levels of theory in addition to recently updated group additivity values. Experimentally measured ignition delay times for propane, the pentane isomers and n-heptane are simulated using NUIGMech1.2 and replacing the thermochemistry of the low-temperature species with the calculated values. For propane, three different thermochemistry sets were calculated, namely CCSD(T)-F12/TZ-F12//B2PLYP-D3/TZ//B2PLYP-D3/TZ (QM1), CCSD(T)-F12/TZ-F12//B2PLYP-D3/TZ//ωB97X-D/TZ (QM2) and B2PLYP-D3/TZ/ωB97X-D/6-31G*//ωB97X-D/6-31G* (QM3). The QM2 results provide parameters to optimize new group additivity (NGA) values which are used to calculate the fourth set of thermochemistry. The model predictions using these four sets are compared to those using NUIGMech1.2 for propane. As the QM1 and QM2 calculations are expensive, the thermochemistry calculated from the QM3 and NGA calculations are used in the pentane isomer and n-heptane models. For all of the models, it is found that the thermochemistry of the species involved in the low-temperature reaction sequence (RH, Ṙ, RO2H, RȮ2, Q˙OOH and Ȯ2QOOH species) significantly affect fuel reactivity. The NGA values were developed based on all of these species except Ȯ2QOOH radicals. The thermochemistry of Ȯ2QOOH species cannot be accurately calculated with the NGA representations due to the importance of non-next-nearest neighbor interactions of –OOH substitution. Further development of the NGA method to capture such interactions is in progress. Overall, the model developed using the NGA thermochemistry shows better agreement with experimental data than the model using thermochemistry from affordable and prominent QM methods, such as QM3. Based on the results presented for propane, the pentane isomers and n-heptane, the thermochemistry calculated using the NGA method can be used to model the oxidation of higher order hydrocarbons at low temperatures.

Accurate thermochemistry prediction of extensive Polycyclic aromatic hydrocarbons (PAHs) and relevant radicals

Polycyclic aromatic hydrocarbons (PAHs) are important intermediates to soot formation in combustion. A reliable database of their thermochemistry is required for the development of chemical kinetic models describing the gas-phase chemistry of hydrocarbon fuels. In this study, temperature-dependent thermodynamic properties are consistently determined using high-accuracy quantum chemistry calculations for an extensive set of PAH compounds. The developed database comprehensively consists of 125 C6-C18 PAH molecules and radicals, which are important and commonly included in chemical mechanisms studies. At the M06-2X/6-311++G(d,p) level of theory, geometry optimizations, vibrational frequency calculations, and dihedral angle scans are performed for all PAH species. The G3 method, together with the atomization reaction approach, is selected to derive the average atomization formation enthalpy. This method produces the most accurate thermochemistry quantities for PAHs, as demonstrated in a previous study. The entropy and heat capacity values are calculated using statistical thermodynamics in MultiWell. These results exhibit good agreement with the databases in literature. To examine the application of the group additivity (GA) method for PAHs, the Bland−Altman plot, a statistical analysis approach, is employed to visualize the agreement between the results from the quantum chemical calculations and GA methods. Two GA methods are examined and significant differences are found, which indicates that GA values of relevant groups need to be further updated. The database of thermodynamic quantities developed in this study are of particular value in modeling studies and important for exploring mechanisms of the PAH growth.

The merit of pressure dependent kinetic modelling in steam cracking.

Renewable cracking feedstocks from plastic waste and the need for novel reactor designs related to electrification of steam crackers drives the development of accurate and fundamental kinetic models for this process, despite its large scale implementation for more than half a century. Pressure dependent kinetics have mostly been omitted in fundamental steam cracking models, while they are crucial in combustion models. Therefore, we have assessed the importance of pressure dependent kinetics for steam cracking via in-depth modelling and experimental studies. In particular we have studied the influence of considering fall-off on the product yields for ethane and propane steam cracking. A high-pressure limit fundamental kinetic model is generated, based on quantum chemical data and group additive values, and supplemented with literature values for pressure dependent kinetic parameters for β-scission reactions and homolytic bond scissions of C2 and C3 species. Model simulations with high-pressure limit rate coefficients and pressure dependent kinetics are compared to new experimental measurements. Steam cracking experiments for pure ethane and propane feeds are performed on a tubular bench-scale reactor at 0.17 MPa and temperatures ranging from 1058 to 1178 K. All important product species are identified using a comprehensive GC × GC-FID/q-MS. For homolytic bond scissions, the inclusion of pressure dependent kinetics has a significant effect on the conversion profile for ethane steam cracking. On the other hand, pressure dependence of C2 β-scissions significantly influences conversion and product species profiles for both ethane and propane steam cracking. The C3 β-scissions pressure dependence has a negligible effect in ethane steam cracking, while for propane steam cracking the effect is non-negligible on the product species profiles.

An extensive theoretical study on the thermochemistry of aromatic compounds: from electronic structure to group additivity values.

An extensive and reliable database of thermodynamic properties of C6-C12 aromatic molecules is constructed by using quantum chemistry calculations. There are 101 molecules in total, which cover a variety of structures including mono-substituted, di-substituted, and bi-cyclic aromatics which can be important intermediates in the combustion of alkylbenzenes. Based on the database, a consistent set of Benson group additive values (GAV) and non-nearest neighbor interactions (NNI) is developed to extend the applicability of Benson's group additivity method for aromatic molecules. Meanwhile, GAVs of existing groups are also updated to improve their accuracy. Geometry optimizations, and vibrational frequency calculations are conducted at the M06-2X/6-311++G(d,p) level of theory. Internal rotor potentials for lower-frequency modes are obtained at the M06-2X/6-31G level of theory. G3 and G4 compound methods are used to derive the 0 K enthalpies of formation via the atomization approach. The entropy and temperature-dependent heat capacity values of all species are calculated via the Master Equation System Solver (MESS) code. This work also provides an extensive literature comparison to validate the calculated results, and good agreement is observed with literature data. The correction terms beyond a group range are explored. The NNIs of di-substituted aromatics with substituents including OH, CHO, and CH3 groups are reported. Entropy reduction is observed in the molecules with two substituents in the ortho position, which mainly derives from the hindered internal rotations. In addition, ring strain corrections (RSC) of dicyclic aromatics are evaluated. The strain energies of molecules with a four-membered side ring are prominently large, as the bond length and bond angle distortions are severely restricted. Ring strain also plays a key role in the C-H bond strength associated with the benzylic carbons in dicyclic aromatics. The loss of a hydrogen atom can destroy the high ring-strain geometry leading to a large C-H bond energy.

Extensive High-Accuracy Thermochemistry and Group Additivity Values for Halocarbon Combustion Modeling

Standard enthalpies, entropies, and heat capacities are calculated for 16,813 halocarbons using an automated high-fidelity thermochemistry workflow. This workflow generates conformers at density functional tight binding (DFTB) level, optimizes geometries, calculates harmonic frequencies, and performs 1D hindered rotor scans at DFT level, and computes electronic energies at G4 level. The computed enthalpies of formation for 400 molecules show good agreement with literature references, but the majority of the calculated species have no reference in the literature. Thus, this work presents the most accurate thermochemistry for many halocarbons to date. This new data set is used to train an extensive ensemble of group additivity values and hydrogen bond increment groups within the Reaction Mechanism Generator (RMG) framework. On average, the new group values estimate standard enthalpies for halogenated hydrocarbons within 3 kcal/mol of their G4 values. A significant contribution towards automated mechanism generation of halocarbon combustion, this research provides thermochemical data for thousands of novel halogenated species and presents a self-consistent set of halogen group additivity values.

Thermochemistry of Oxygen-Containing Organosilane Radicals and Uncertainty Estimations of Organosilane Group-Additivity Values.

Si-C-H-O-containing radicals are important intermediates during the combustion and pyrolysis of precursors applied for the gas-phase synthesis of silica nanoparticles. Despite the industrial importance of silica nanoparticles, a comprehensive thermodynamics database of organosilane species is still missing. This work presents thermochemical data of 91 Si-C-H-O radical species. Quantum-chemical calculations and isodesmic reaction schemes are used to determine the standard enthalpy of formation, entropy, and heat capacities covering the 298-2000 K temperature range. In addition, 90 group-additivity values (GAVs) are calculated, which cover all relevant group increments. A combinatorial approach is used to ensure that all possible group increments are considered. The theoretically calculated species are used as a training set to derive 90 GAVs of Si-C-H-O radical species for the first time. In addition, uncertainty contributions of GAVs were estimated. These uncertainty estimates also comprise GAVs that were previously derived to compute thermochemical data of stable Si-C-H species and radicals as well as stable Si-C-H-O compounds. Therefore, uncertainty contributions of GAVs for a whole set of 243 group increments used to predict thermochemical data of Si-organic species are reported.

Standard enthalpies of formation of N,N′-(1,3-phenylene)bis(phthalimide) and N,N′-(1,3-phenylene)bis(phthalimide-5-carboxilic acid)

N,N′-(1,3-phenylene)bis(phthalimide) and N,N′-(1,3-phenylene)bis(phthalimide-5-carboxilic acid), were synthetized in solid phase without solvents, using mechanochemistry; the first compound could be purified with a high mole fraction. However, it was not possible to obtain the second with high purity. The thermochemical properties of compound N,N′-(1,3-phenylene)bis(phthalimide) were determined from experimental data,. The enthalpy of fusion, temperatures of fusion and decomposition as well as heat capacities as a function of temperature, were acquired by means of Differential Scanning Calorimetry (DSC). The standard enthalpy of formation in solid phase was determined from the energy of combustion, which was obtained using combustion calorimetry. Its enthalpy of formation in gas phase was calculated using the standard enthalpy of formation in solid phase as well as the enthalpy of sublimation, which was determined by thermogravimetric data. Experimental values for N,N′-(1,3-phenylene)bis(phthalimide) and three methods of contribution of groups, were used to estimate the enthalpy of formation in gas phase for N,N′-(1,3-phenylene)bis(phthalimide-5-carboxilic acid). In order to make the estimation, it was necessary to calculate some group additivity values (GAVs), corresponding to cyclic imides.

Thermochemistry of organosilane compounds and organosilyl radicals

Si–C–H-containing radicals and stable species are present in the oxidation of silicon-organic compounds such as methyl and ethyl silanes, which are frequently-used precursors for the synthesis of silicon-based nanoparticles and coatings via combustion processes. Silicon-containing intermediates interact with flame radicals and thus play a major role in flame chemistry and influence flame propagation. Mechanistic understanding of these effects is hampered by very limited thermochemical properties available for relevant organosilane species. This paper presents quantum-chemical calculations and isodesmic reaction schemes for the determination of temperature-dependent heat of formation, entropy, and heat capacity of Si–C–H radicals and molecules, from which group additivity values (GAVs) were obtained from combinatorial considerations. The data for 22 stable Si–C–H species are revised using isodesmic reactions and the related 24 GAVs were refined by considering 19 additional stable Si–C–H species. In addition, quantum chemical calculations are made to calculate the thermochemistry of 61 radicals and used to derive 56 GAVs for Si–C–H containing radicals for the first time.

A group additivity methodology for predicting the thermochemistry of oxygen‐containing organosilanes

AbstractA combinatorial approach was applied to devise a set of reference Si–C–O–H species that is used to derive group‐additivity values (GAVs) for this class of molecules. The reference species include 62 stable single‐bonded, 19 cyclic, and nine double‐bonded Si–C–O–H species. The thermochemistry of these reference species, that is, the standard enthalpy of formation, entropy, and heat capacities covering the temperature range from 298 to 2000 K was obtained from quantum chemical calculations using several composite methods, including G4, G4MP2, and CBSQB3, and the isodesmic reaction approach. To calculate the GAVs from the ab initio based thermochemistry of the compounds in the training set, a multivariable linear regression analysis is performed. The sensitivity of GAVs to the different composite methods is discussed, and thermodynamics properties calculated via group additivity are compared with available ab initio calculated values from the literature.

Investigating the impacts of thermochemical group additivity values on kinetic model predictions through sensitivity and uncertainty analyses

The accuracy of species thermochemical properties is important for predicting combustion characteristics by chemical kinetic models due to their impacts on chemical equilibria of elementary reactions and on backward rate coefficients. As they are frequently estimated based on the group additivity method, the underlying group values directly influence the model prediction accuracy. While a number of studies have recently aimed to improve the accuracy of group values, the dependence of kinetic model predictions on the different groups has not yet been investigated in detail before. In the present work, the impact of group thermochemical parameters on ignition prediction is systematically analyzed by means of sensitivity analysis, employing the oxidation of 2-methylhexane (2-MH) as an example. Very high sensitivities are observed at intermediate temperatures for the peroxy group OO/C/H and its adjacent groups in low-temperature intermediate species. Based on uncertainty analysis, optimization potentials are then determined for the group values of enthalpy of formation, standard entropy, and heat capacity, and they are observed to be considerable for certain groups, especially for the enthalpy of formation values of OO/C/H and its adjacent groups. It is also found that the correct and consistent application of optical isomer corrections in the group additivity method is essential for accurate model predictions. The high optimization potentials of a number of groups motivate the extension of an established kinetic model optimization framework as part of this work, calibrating jointly the rate rules and group values against sets of both global model prediction targets and known species thermochemical properties. This methodology is applied to the considered 2-MH model, yielding very good posterior predictions of ignition characteristics. Overall, the results of this study demonstrate that uncertainties in certain group values will strongly propagate into the model prediction, which motivates future research towards a reduction of those uncertainties.

Thermochemistry and Group Additivity Values for Fused Two-Ring Species and Radicals.

Motivated by a lack of understanding in the chemical mechanisms of alkylaromatic pyrolysis, the thermochemistry of fused two-ring aromatic molecules and radicals was calculated in this work using the CBS-QB3 level of theory. The enthalpies of formation of some fused ring species differ by as much as 13 kcal/mol from previous estimates. New group values were defined to facilitate better thermochemistry estimates in the future and were found to match the CBS-QB3 calculated values with an average deviation of 0.4 kcal/mol and a standard deviation of 0.9 kcal/mol, a substantial improvement from previous estimation methods. We discuss the thermochemical characteristics of the various polycyclic and radical groups developed in this work.

Benson group additivity values of phosphines and phosphine oxides: Fast and accurate computational thermochemistry of organophosphorus species.

Composite quantum chemical methods W1X-1 and CBS-QB3 are used to calculate the gas phase standard enthalpy of formation, entropy, and heat capacity of 38 phosphines and phosphine oxides for which reliable experimental thermochemical information is limited or simply nonexistent. For alkyl phosphines and phosphine oxides, the W1X-1, and CBS-QB3 results are mutually consistent and in excellent agreement with available G3X values and empirical data. In the case of aryl-substituted species, different computational methods show more variation, with G3X enthalpies being furthest from experimental values. The calculated thermochemical data are subsequently used to determine Benson group additivity contributions for 24 Benson groups and group pairs involving phosphorus, thereby allowing fast and accurate estimations of thermochemical data of many organophosphorus compounds of any complexity. Such data are indispensable, for example, in chemical process design or estimating potential hazards of new chemical compounds. © 2018 Wiley Periodicals, Inc.

Response surface and group additivity methodology for estimation of thermodynamic properties of organosilanes

AbstractGroup additivity methods simplify the determination of thermodynamic properties of a wide range of chemically related species involved in detailed reaction schemes. In this paper, we expand Benson's group additivity method to organosilanes. Based on quantum‐chemical calculations, the thermodynamic data of 22 stable silicon‐organic species are calculated, presented in the form of NASA polynomials, and compared to the available experimental data. Based on this theoretical database, a complete set of 24 Si‐ and C‐atom‐centered, single‐bonded and nonradical group additivity values for enthalpy of formation, standard entropy, and heat capacity at temperatures from 200 to 4000 K is derived through unweighted multivariate linear regression.

Experimental and Kinetic Modeling Study of Cyclohexane Pyrolysis

The pyrolysis of undiluted cyclohexane has been studied in a continuous flow tubular reactor at temperatures from 913 to 1073 K and inlet feed flow rates in the range 288–304 g·h–1 at 0.17 MPa reactor pressure with average reactor residence time of 0.5 s calculated based on the pressure in the reactor, the temperature profile along the reactor, and the molar flow rate along the reactor estimated by the logarithmic average of the inlet and outlet molar flows. The reactions lead to conversions between 2% and 95%. Forty-nine products were identified and quantified using two-dimensional gas chromatography equipped with thermal conductivity and flame ionization detectors. The products with molecular weights between those of hydrogen and naphthalene constitute more than 99 mass % of the total products. A kinetic mechanism composed exclusively of elementary step reactions with high pressure limit rate coefficients has been generated with the automatic network generation tool “Genesys”. The kinetic parameters for the reactions originate either directly from high level ab initio calculations or from reported group additive values which were derived from ab initio calculations. The Genesys model performs well when compared to five models available in the literature, and its predictions agree well with the experimental data for 15 products without any adjustments of the kinetic parameters. Reaction path analysis shows that cyclohexane consumption is initiated by the unimolecular isomerization to 1-hexene but is overall dominated by hydrogen abstraction reactions by hydrogen atoms and methyl radicals. Dominant pathways to major products predicted with the new model are discussed and compared to other well performing models in the literature.