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The effect of Ga and V as support-modifier and promoter of NiMoV/Al2O3-Ga2O3 catalyst on hydrogenation (HYD) and hydrodesulfurization (HDS) activities was studied. The catalysts were characterized by elemental analysis, textural properties, XRD, XPS, EDS elemental mapping and High-resolution transmission electron microscopy (HRTEM). The chemical analyses by X-ray Fluorescence (XRF) and CHNS-O elemental analysis showed results for all compounds in agreement, within experimental accuracy, according to stoichiometric values proposed to Mo/Ni = 6 and (V+Ni)/(V+Ni+Mo) = 0.35. The sol-gel synthesis method increased the surface area by incorporation of Ga³⁺ ions into the Al₂O₃ forming Ga-O-Al bonding; whereas the impregnation synthesis method leads to decrease by blocking of alumina pores, as follows NiMoV/Al-Ga(1%-I) < NiMoV/Al-Ga(1%-SG) < NiMo/Al₂O₃ < Al₂O₃-Ga₂O₃(1%-I) < Al₂O₃-Ga₂O₃(1%-SG) < Al₂O₃, propitiating Dp-BJH between 6.18 and 7.89 nm. XRD confirmed a bulk structure typical of (NH₄)_4[NiMo₆O₂₄H₆]•5H₂O and XPS the presence at the surface of Mo⁴⁺, Mo⁶⁺, NixSy, Ni²⁺, Ga³⁺ and V⁵⁺ species, respectively. The EDS elemental mapping confirmed that Ni, Mo, Al, Ga, V and S are well-distributed on Al₂O₃-Ga₂O₃(1%-SG) support. The HRTEM analysis shows that the length and stacking distribution of MoS₂ crystallites varied from 5.07 to 5.94 nm and 2.74 to 3.58 with synthesis method (SG to I). The results of the characterization sulfided catalysts showed that the synthesis method via impregnation induced largest presence of gallium on the surface influencing the dispersion V⁵⁺ species, this effect improves the dispersion of the MoS₂ phase and increasing the number of active sites, which correlates well with the dibenzothiophene HDS and naphthalene HYD activities. The dibenzothiophene HDS activities with overall pseudo-first-order rate constants’ values (k_HDS) from 1.65 to 7.07 L/(h·mol·m²) follow the order: NiMoV-S/Al-Ga(1%-I) < NiMo-S/Al₂O₃ < NiMoV-S/Al-Ga(1%-SG), whereas the rate constants’ values (k) of naphthalene HYD from 0.022 to 2.23 L/(h·mol·m²) as follow: NiMoV-S/Al-Ga(1%-SG) < NiMo-S/Al₂O₃ < NiMoV-S/Al-Ga(1%-I). We consider that Ga and V act as structural promoters in the NiMo catalysts supported on Al₂O₃ that allows the largest generation of BRIM sites for HYD and CUS sites for DDS.