A new method for reactivating the supported deep hydrotreatment CoMo/Al2O3 and NiMo/Al2O3 catalysts after oxidative regeneration

A new method for the reactivation of CoMo/Al2O3 and NiMo/Al2O3 catalysts for the deep hydrotreatment of diesel fuel after the oxidative regeneration stage involves impregnating regenerated catalysts with aqueous solutions of such chelating compounds as citric and oxalic acids, ethyleneglycol, and diethyleneglycol with subsequent drying. The activity of reactivated catalysts subjected to such treatment can be higher than for fresh samples. The effect of the nature and amount of introduced chelates on the activity of the IK-GO-1 catalyst in the hydrotreatment of straight-run diesel fuel is studied. Treating an oxidized sample with a solution containing both citric acid and glycol at the optimum molar ratio of total chelate compounds to total metals (0.5–1.0) yields the best results. Regenerated catalysts thus enable the production of ultralow sulfur diesel fuels (10 ppm) at an initial hydrotreatment temperature 10–15°C lower than for catalysts after their oxidative regeneration and 3–4°C lower than for fresh catalysts.