Experiments with a duration of 60 and 200 hours are carried out at different contact times of 0.33, 0.66, and 1.33 hours (the specific volumetric rate is 3.0, 1.5, and 0.75 h, and the pressure is 4.0 MPa) during hydrotreatment of diesel fuel with a high silicon content. Experiments with a run time of 200 hours showed that the silicon concentration in the front layer of the NiMo/AlO catalyst does not change as the contact time grows, indicating that the maximum capacity value of ~5 wt. % is reached. The absence of the influence of external mass transfer on the adsorption of silicon, as well as on the conversion of sulfur during testing of the catalyst in a laboratory setup, is experimentally studied and theoretically substantiated. The values of linear feed rates of raw materials are determined, showing no influence of external mass transfer on both the process of silicon adsorption and sulfur conversion.
Petrov et al. (Wed,) studied this question.