Intrinsic potential of alumina-supported CoMo catalysts in HDS: Comparison between γc, γT, and δ-alumina

► CoMoS catalysts were prepared on different kinds of alumina. ► Optimization of the promotion by using Co complexes on already sulfided MoS2. ► Characterization of the solids by XPS and IR(CO) at low temperature. ► Highly efficient catalysts in thiophene and 4,6-DMDBT HDS. ► TOF was calculated using XPS, elemental analysis, and microscopy measurements.