The influence of alumina precursor (pseudoboehmites) in CoMo/ASA + Al2O3 catalysts on catalytic activity in FCC gasoline hydrotreating has been studied. Pseudoboehmites prepared by alcoholate, precipitate and hydro-thermal technologies were used. Parent powders, supports and catalysts were characterized by low-temperature N2 adsorption, TPD of ammonia, STEM, HRTEM, UV-vis spectroscopy. Catalysts were tested in hydrotreating of the model FCC gasoline feedstock. It is shown that the choice of pseudoboehmite has significant effect on textural, acid and mechanical properties of supports and catalysts, as well as dispersity of the active phase. The type of pseudoboehmite affects the amount of tetrahedral cobalt in catalysts that changes surface activity per 1 g of the catalyst. The linear dependence between the ratio of the medium and weak acid sites and catalyst selectivity was found. It is established that isomerizing activity is higher than the hydrogenating one, when medium/weak acid sites ratio in the catalyst is lower than 1.85.

Abstract CoMo/Al2O3-ASA catalysts with different Al2O3/ASA ratio have been studied. The amount of ASA (Si/Al ratio 0.25 wt./wt.) varied from 0 to 100 % in the support. Supports and catalysts were characterized by low-temperature N2 adsorption-desorption, TPD-NH3, IRS of adsorbed pyridine, HRTEM, UV-vis spectroscopy, XPS, XRD, bulk crushing strength. Catalysts were tested in hydrotreating of the model FCC gasoline containing 250 ppm of sulfur from thiophene, 40 wt.% of toluene, 40 wt.% of heptane and 20 wt.% of 1-hexene. It was shown that the introduction of ASA to the support increased the amount of weak Brønsted acid sites and weak and medium Lewis acid sites. The addition of ASA changed the morphology of sulfide active component and extract Co from the composition of the CoMoS phase. It was shown that presence of more than 50 wt.% of ASA in the samples demonstrated significant changes in the selectivity of CoMo catalysts.

Because hydrotreating (HDT) of FCC gasoline is one of the important processes used to prepare such gasoline for blending, the development of a catalyst for this process is of great interest. Currently, the industrial HDT of FCC gasoline con-sists of two stages and the creation of a new catalyst for one-stage HDT will make this process more efficient. Recently, our group has developed the CoMo/Al2O3-ASA catalyst and studied the influence of Si/Al ratio on the target reactions of HDT pro-cess. Despite the high selectivity and activity, the catalyst with ASA is not applicable in industry because of its low strength. The present work moves forward to study the influence of the ASA content in the catalyst support and clarify the possibility to develop the catalyst that combines high activity and selectivity in HDT reactions with successful performance. Here we show that the CoMo catalyst with ASA/Al2O3 molar ratio 1/1 in the support is the best combination for FCC gasoline hydrotreatment due to exceptional properties of the catalyst composition.

A NiMoP/Al2O3 catalyst deactivated at the industrial plant was subjected to oxidative regeneration and reactivation with water and an aqueous solution of citric acid. The catalyst was studied at all stages by XRD, UV–vis, Raman spectroscopy, FTIR spectroscopy, XPS and HRTEM methods. The catalyst samples after oxidative regeneration, treatment with water and rejuvenation with citric acid were tested in hydrotreatment of the model feedstock and straight-run gasoil. It was established that the regenerated catalyst contained phosphorus strongly bound to the support and soluble or insoluble Ni and Mo compounds. The catalyst after water treatment contained only insoluble Ni and Mo compounds and a phosphate monolayer, while treatment with citric acid resulted in the formation of citrate complex compounds. Ni and Mo compounds in the sulfide form, which were obtained from insoluble components, showed high activity in the target hydrotreating reactions.