CoMo/SBA-15 catalysts prepared with EDTA and citric acid and their performance in hydrodesulfurization of dibenzothiophene

Abstract

A series of CoMo catalysts supported on SBA-15 were prepared with ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) as chelating agents. The catalysts were prepared varying the MoO3 charges (6, 12 and 18wt.%). They were characterized by several techniques (N2 physisorption, powder and small-angle XRD, TPR, DRS and HRTEM) and tested in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalysts prepared without chelating agents showed a crystalline phase (β-CoMoO4) since the lowest metal charge, detected by powder XRD. The addition of chelating agents in the impregnation solution avoided the precipitation of this crystalline phase on the SBA-15 surface. HRTEM measurements exhibited smaller MoS2 particles when the catalysts were prepared with chelating agents. Highly active catalysts were synthesized with EDTA and CA. The increase in the metal charges in the CoMo/SBA-15 catalysts without chelating agents resulted in little increment in the catalytic activity. However, the catalytic activity showed an important enhancement when the metal species were impregnated in presence of EDTA or CA.