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In this work, we report a statistically significant increase in the rates of direct C–S bond scission of dibenzothiophene when co-reactants such as naphthalene, quinoline, and indole are present during its hydrodesulfurization over a Ni–MoS2/γ-Al2O3 catalyst. The competitive adsorption of these compounds on the same active sites has usually been associated with inhibitory effects of sulfur elimination. However, we carried out statistically designed experiments at temperatures between 260 and 300 °C, concentrations of dibenzothiophene between 1.0 and 3.7 wt%, and concentrations of the co-reactants between 0.13 and 0.52 wt%, and observed that the kinetic constant of the direct desulfurization pathway can increase up to 200% when either naphthalene, indole, or quinoline is co-fed to the reaction system at 260 °C and 3.7 wt% of dibenzothiophene. Therefore, the classical paradigm that aromatics and nitrogen heterocycles always inhibit hydrodesulfurization needs reexamination.

The competitive adsorption of aromatics and nitrogen heterocycles on the active sites of solid catalytic sulfides (Ni(Co)-MoS2 dispersed over oxidic carriers) typically causes inhibitory effects during the hydropurification of sulfur heterocycles. Contrary to this typical behavior, we report herein that it is possible to promote the scission of the C-S bond of refractory dibenzothiophene by co?feeding the above compounds during hydropurification over a conventional Ni-MoS2/Al2O3 catalyst. Particularly, we prove that at temperatures between 240 and 300°C and concentrations of dibenzothiophene between 1.0 and 3.7 wt.%, the desulfurization of dibenzothiophene is promoted by increasing its conversion up to 370% when either naphthalene, indole, or quinoline are co-fed to the reaction system. The work highlights the following: (i) lower temperatures and higher concentrations of the sulfur heterocycle enhanced the cleavage of the C-S bond from dibenzothiophene; (ii) it is possible to promote hydropurification reactions regardless of the nature of the of co-reactants; namely: a fused aromatic ring -naphthalene-, or a fused nitrogen heterocycle with a lone pair belonging to the pi-system -quinoline- or not -indole-.

The competitive adsorption of aromatics and nitrogen heterocycles on the active sites of solid catalytic sulfides (Ni(Co)-MoS2 dispersed over oxidic carriers) typically causes inhibitory effects during the hydropurification of sulfur heterocycles. Contrary to this typical behavior, we report herein that it is possible to promote the scission of the C-S bond of refractory dibenzothiophene by co?feeding the above compounds during hydropurification over a conventional Ni-MoS2/Al2O3 catalyst. Particularly, we prove that at temperatures between 240 and 300°C and concentrations of dibenzothiophene between 1.0 and 3.7 wt.%, the desulfurization of dibenzothiophene is promoted by increasing its conversion up to 370% when either naphthalene, indole, or quinoline are co-fed to the reaction system. The work highlights the following: (i) lower temperatures and higher concentrations of the sulfur heterocycle enhanced the cleavage of the C-S bond from dibenzothiophene; (ii) it is possible to promote hydropurification reactions regardless of the nature of the of co-reactants; namely: a fused aromatic ring -naphthalene-, or a fused nitrogen heterocycle with a lone pair belonging to the pi-system -quinoline- or not -indole-.

The effect of the milk-whey relation over the physicochemical properties (pH, total acidity, soluble solids and syneresis) and rheology (deformation rate, apparent viscosity, flow behavior index and consistency index) of a fermented dairy drink was studied. A completely randomized experimental design of two factors: percentage of whey (0, 5, 10 and 15% w/w) and type of milk (whole and skim) was used. The significance was determined using an analysis of variance (ANOVA). All properties analyzed except pH had statistically significant differences (P

The work presents a kinetic study of the simultaneous hydrodesulfurization of dibenzothiophene and hydrogenation of aromatics with different chemical structures. This kind of studies are seldom reported, since many authors deal almost exclusively with hydrodesulfurization. Furthermore, most of these authors employ power rate laws for kinetic modelling neglecting a rigorous analysis of the thermodynamic parameters of the reactions; namely, adsorption enthalpies and entropies.Considering this fact, we decided to base our kinetic modelling on a Langmuir-Hinshelwood-Hougen-Watson (LHHW) formalism testing the hypothesis of the existence of one or two different catalytic sites for hydrogenation and desulfurization. The consistency of the aforementioned thermodynamic parameters was assessed considering the criteria postulated by Boudart.Our results allowed concluding that a LHHW model considering two actives sites provides a statically satisfactory fitting of experimental data. In addition, it was possible to determine that inhibition effects of aromatics on hydrodesulfurization exist but depend to some extent on the molecular structure of the aromatic.On the other hand, this work also contributes by providing experimental values of adsorption constants of compounds reacting under hydrotreatment conditions which despite the significant advances in theoretical calculations are not yet available in open literature.