Thermodynamic analysis of a reactive distillation process for deep hydrodesulfurization of diesel: Effect of the solvent and operating conditions

The effect of the solvent type, operating pressure and catalyst loading for deep hydrodesulfurization of diesel through a reactive distillation process has been analyzed. The analysis considers the computation of reactive residue curve maps for the hydrodesulfurization of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in a simple reactive batch distillation process. For the computation of the reactive residue curves, the hydrogenolysis and hydrogenation reaction paths were considered. The visualization of the reactive residue curves is posed in terms of elements. Through the computation of the reactive residue curve maps it was possible to reproduce the experimental information stating that DBT is preferentially converted following the hydrogenolysis reaction route, while 4,6-DMDBT is mostly eliminated by the hydrogenation reaction route. From the reactive residue curve maps the effect of the solvent, pressure and catalyst loading on the conversion of 4,6-DMDBT was studied. It was found that when n-hexadecane (n-C16H34) is used as the solvent medium and the operating pressure is set to 10 atm a complete conversion of 4,6-DMDBT is achieved. The same conversion is achieved using tetraline (C10H12) as solvent but the pressure must be increased up to 30 atm and a higher amount of catalyst is required.