Study of the effect of the amount of Ni on the hydrodesulfurization activity of Ni-Mo catalysts supported on Mgo-TiO2

Abstract

The activity of hydrodesulfurization catalysts depends on the formation of the active NiMoS phases. Which requires Ni and Mo to interact during catalyst preparation from solution, impregnation, calcination and sulfidation. However, the use of new supports such as MgO-TiO2 can avoid the interaction between Ni and Mo, since Ni strongly interacts with MgO forming the spinel NiMgO. Therefore, the addition of TiO2 is expected to modify the MgO surface to avoid Ni-MgO interaction and favor the dispersion and activity of the active NiMoS species. In order to know if the Ni interacts with the support or with the Mo during the impregnation and calcination of the catalysts, in this work we present the strategy of increasing the amount of Ni: this will allow us to appreciate if the Ni interacts with the Mo and the effect of Mg on the Mo precursors formed after impregnation in a basic medium (pH 9) and in a neutral medium (pH 7). The results obtained by means of Raman and UV-Vis diffuse reflectance spectroscopy showed that during the impregnation, the Ni2+ /MoO42- species are formed in the synthesized solids at pH= 7 and 9. However, after calcination, the Ni/MgO species in both solids, prepared at pH= 7 and 9, which is more evident when the Ni concentration is higher.