Effect of the Gallium and Vanadium on the Dibenzothiophene Hydrodesulfurization and Naphthalene Hydrogenation Activities Using Sulfided NiMo-V2O5/Al2O3-Ga2O3

Abstract

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 (kHDS) 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.

Al2O3-MgO Supported Ni, Mo, and NiMo Mixed Phosphidic-Sulphidic Phase for Hydrotreating of Stearic and Oleic Acids Into Green Diesel

“…Results obtained from XRF and EDX chemical analyses of Al 2 O 3 -MgO, NiP-S/ γ -Al 2 O 3 -MgO, MoP-S/ γ -Al 2 O 3 -MgO, and NiMoP-S/ γ -Al 2 O 3 -MgO are shown in Table 1 . The differences between experimental and nominal contents for all catalysts were within experimental accuracy, whose deviations could be related to the steps applied to synthesizing the supports and catalysts ( Puello-Polo et al, 2020 ). Hence, the Al/Mg, Ni:Mo, Ni:P, and Mo:Ni:P atomic ratios proposed were similar to the designed formulation of the supports and catalysts in this work.…”

“…The EDS elemental mapping confirmed the well-distributed presence of the atoms constituting the catalysts on the support, i.e., Mo, Ni, Al, O, P, Mg, and S. However, the micrographs show the greater intensity of mapping in a few catalyst zones for Ni and Mo atoms associated to the solubility of the precursors, suggesting that some of these atoms could precipitate. But they are not dispersing on the whole selected area forming a metal rich-aggregate “cluster” in the NiP-S/γ-Al 2 O 3 -MgO and MoP-S/γ-Al 2 O 3 -MgO catalysts ( Puello-Polo et al, 2020 ).…”

Hydrodesulfurization of 4,6-Dimethyldibenzothiophene and the Diesel Oil Fraction on NiMo Catalysts Supported over Proton-Exchanged AlMCM-41 and TiMCM-41 Extrudates

“…In both cases, the values of BE are somewhat higher than those usually observed at for stoichiometric MoO 3 (232.9 and 236.1 eV) [61], suggesting some interactions of molybdenum species with the support surface. The less-intense signals for the Mo 3d 5/2 −Mo 3d 3/2 doublet (i.e., BE at 230.8 and 234.1 eV, and at 231.5 and 234.1 eV for the NiMo/HAlMCM-41 and NiMo/HTiMCM-41 samples, respectively) are linked with the presence of Mo (IV) [62].…”

Management of γ-Alumina with High-Efficient {111} External Surfaces for HDS Reactions

“…The catalyst support plays an important role in the distribution active phase and determining catalytic performance. For the HDS catalyst, the most frequently used support is alumina [4][5][6][7][8] owing to its tunable and stable mechanical characteristics and low cost, yet conventional alumina interacts strongly with metal oxide precursors, which may affect their sulfidity [9]. Until recently, the exact role of how oxide affects the activities of catalysts is still not entirely resolved [10].…”