Graph-Based Method for the Automated Calculation of Thermochemical Properties of Components and Intermediate Species in the Hydroprocessing of Light Oil Fractions

Dávila, O G Ytalo; Martinis, Mladen

doi:10.1021/ie101657v

Cited by 4 publications

(5 citation statements)

References 32 publications

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“…Finally, the values obtained from our group additivity results were compared against the results from a similar approach recently published by Dávila et al Table compares the deviations from experimental enthalpies of formation for both group additivity schemes for a subset of molecules (molecules (1), (2), (3), (4), (5), (10), (11), (35), (36), and (44)) (values are listed in Supporting Information). Both sets of values do reasonably well against experiment.…”

Section: Resultsmentioning

confidence: 99%

“…In this work, we performed QM calculations on a set of fifty-seven acyclic and cyclic carbenium ions, calculated enthalpies of formation for each using isodesmic reactions, and derived a set of Benson-like group values in order to allow for modeling of hydrocarbon conversion chemistries involving carbenium ions. Our results will be compared to experimental values where available, as well as to enthalpies of formation obtained from Dávila et al’s recent set of group values …”

Section: Introductionmentioning

confidence: 95%

“…Other authors have derived group values for enthalpies of formation for simple carbenium ions and select allylic carbenium ions . However, additional groups are required to calculate enthalpies of formation for all potential allylic carbenium acyclic ions, as well as cyclic molecules.…”

Section: Introductionmentioning

confidence: 99%

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Group Additivity Determination for Enthalpies of Formation of Carbenium Ions

Bjorkman

Sung

Mondor

et al. 2014

Ind. Eng. Chem. Res.

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Modeling of acid-catalyzed hydrocarbon conversion processes at the mechanistic level requires rate coefficients for a large number of reactions. The computational demand of finding activation energy barriers for each reaction is substantially reduced by employing structure–reactivity correlations such as the Evans–Polanyi relationship that correlates activation energy with the enthalpy of reaction. However, there are many species for which the enthalpies of formation are unknown. Therefore, group additivity methods to specify enthalpies of formation for each species involved in the reaction network are valuable. Quantum mechanical (QM) calculations and isodesmic reactions were used to calculate enthalpies of formation for a number of acyclic and cyclic carbenium ions, including allylic carbenium ions. These values compare favorably with experimental values, establishing Gaussian-4 as an accurate QM method for these calculations. Using these values, Benson-type group additivity values for enthalpies of formation were then derived through multiple linear regression. Enthalpies of formation values calculated from the group additivity scheme capture experimental and QM enthalpies of formation well and enhance the range of species that can be described by the group additivity approach.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

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Group Additivity Determination for Enthalpies of Formation of Carbenium Ions

Bjorkman

Sung

Mondor

et al. 2014

Ind. Eng. Chem. Res.

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show abstract

“…This ensures that the test set is representative of the studied types of carbenium ions. 47 and Davila et al 46 in Table 6. There is no consensus in the reported literature values, but the values in this work match closely with one of the values from literature for every group.…”

Section: Group Additive Valuesmentioning

confidence: 94%

“…44,45 A limited number of group additive values (GAVs) for the enthalpy of formation have been determined in the past via quantum chemical calculations. 46,47 Bjorkman et al determined 16 GAVs for the calculation of enthalpies of formation based on quantum chemical calculations at the G4 level of theory. 47 However, these GAVs limit themselves to the description of paraffinic, olefinic, and a limited set of aromatic carbenium ions.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Group Additive Values for Thermodynamic Carbenium Ion Property Prediction

Ureel

Vermeire

Sabbe

2022

Ind. Eng. Chem. Res.

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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.

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Symmetry calculation for molecules and transition states

et al. 2014

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The symmetry of molecules and transition states of elementary reactions is an essential property with important implications for computational chemistry. The automated identification of symmetry by computers is a very useful tool for many applications, but often relies on the availability of three-dimensional coordinates of the atoms in the molecule and hence becomes less useful when these coordinates are a priori unavailable. This article presents a new algorithm that identifies symmetry of molecules and transition states based on an augmented graph representation of the corresponding structures, in which both topology and the presence of stereocenters are accounted for. The automorphism group order of the graph associated with the molecule or transition state is used as a starting point. A novel concept of label-stereoisomers, that is, stereoisomers that arise after labeling homomorph substituents in the original molecule so that they become distinguishable, is introduced and used to obtain the symmetry number. The algorithm is characterized by its generic nature and avoids the use of heuristic rules that would limit the applicability. The calculated symmetry numbers are in agreement with expected values for a large and diverse set of structures, ranging from asymmetric, small molecules such as fluorochlorobromomethane to highly symmetric structures found in drug discovery assays. The new algorithm opens up new possibilities for the fast screening of the degree of symmetry of large sets of molecules.

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Graph-Based Method for the Automated Calculation of Thermochemical Properties of Components and Intermediate Species in the Hydroprocessing of Light Oil Fractions

Cited by 4 publications

References 32 publications

Group Additivity Determination for Enthalpies of Formation of Carbenium Ions

Group Additivity Determination for Enthalpies of Formation of Carbenium Ions

Ab Initio Group Additive Values for Thermodynamic Carbenium Ion Property Prediction

Symmetry calculation for molecules and transition states

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