Thermochemistry of 1-methylnaphthalene hydroconversion : comparison of group contribution and ab-initio models.

Abstract : As a necessary step in the development of microkinetic models for the hydroconversion of heavy hydrocarbon fractions, we report an assessment of various DFT models for the calculation of molecular thermochemical properties in comparison with Benson's group contribution method for reactants, intermediates and products involved in the hydrogenation of 1-methylnaphatalene. The association of the G4 level with homodesmic decomposition schemes (HI-G4-iso method) has significantly improved the accuracy of the thermodynamic calculated properties when the resemblance of reactants and products are taken into account. Although smaller deviations are observed for Benson's GA method, sorne limitations appear when position isomers are included. This gap can be fulfilled with homodesmic/DFT models, whose deviations are not so far from those obtained with Benson's GA method.