Hydrotreating stands as a critical facet in oil refining to meet stringent environmental norms, facilitating the production of ultra-low sulfur fuels. This study delves into the concurrent ...hydrodesulfurization of DBT and 4,6-DMDBT utilizing a NiMoP/Al2O3 catalyst. Through 27 experiments, parameters such as temperature, pressure, concentrations, and WHSV were scrutinized to derive kinetic insights. Employing five power law (PL) models, encompassing both global and individual HDS variations, parameter estimation employed weighted least squares optimization techniques like particle swarm and Gauss-Newton methods. Rigorous statistical analyses underlined model performance nuances. While the ‘global HDS of 4,6-DMDBT’ model met the chi-squared test, the ‘global HDS of DBT’ revealed complexities beyond PL modeling. Notably, the negative hydrogenation order for DBT implied significant adsorption effects. Apparent activation energies, approximately 117 kJ mol−1 for DBT and 124 kJ mol−1 for 4,6-DMDBT, were discerned using global models.
•Deep hydrodesulfurization of DBT and 4,6-DMDBT was evaluated in fixed-bed reactor.•Estimation and statistical evaluation of kinetic parameters were performed.•A power-law model considering individual DBT routes fits the experimental data well.•The reparameterization technique and Arrhenius equation optimization reduced parametric correlation.
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•Deep hydrodesulfurization of dibenzothiophene was evaluated in a fixed-bed reactor.•The CoMoP catalyst was more active while NiMoP showed higher hydrogenation power.•Estimation and ...statistical evaluation of kinetic parameters were performed.•A power-law model considering two parallel routes fit well the experimental data.•The good model prediction was validated with data not used in parameter estimation.
Over the last decades, the regulatory agencies, aiming to limit vehicle emissions, established more stringent fuel specifications, including ultra-low sulfur contents in diesel and gasoline. In such way, hydrodesulfurization (HDS) is a key process in the oil refining scheme for producing low sulfur fuels. The evaluation of the HDS reaction kinetics of refractory compounds, as dibenzothiophene (DBT), is an important tool in the search for improving the activity of usual industrial catalysts. In this context, the main objective of this work was the estimation of kinetic parameters of DBT HDS reactions using CoMoP/Al2O3 and NiMoP/Al2O3 catalysts at operational conditions which provide a wide range of DBT conversions. The estimation results were evaluated using statistical tests as t-Student and chi-square. Good fits to the evaluated experimental data were provided by two power-law models with different levels of detail: one considering the global DBT conversion only and the other considering a reactional scheme with two parallel routes (direct desulfurization to biphenyl and hydrogenation to cyclohexylbenzene). The apparent activation energies found were of the order of 90 to 100 kJ mol−1. Regarding the biphenyl hydrogenation to cyclohexylbenzene, the parameter estimation was hindered because this reaction is expected to be significant at conditions with high DBT conversions only.
