Hydrotreating of straight-run diesel fraction over mixed nimows/al2o3 sulfide catalysts

International audienceThe catalytic properties of trimetallic NiMoWS catalysts supported on alumina are studied in the process of straight-run diesel fraction hydrotreating. It is shown that the nature of the oxide precursor of the mixed NiMoWS active phase strongly affects catalyst activity in the hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and hydrogenation (HYD) of polycyclic aromatic hydrocarbons (PAH). The NiMoWS/Al2O3 catalyst synthesized from the mixed H4SiMo3W9O40 heteropoly acid is more efficient than the sample prepared from a mixture of individual H4SiMo12O40 and H4SiW12O40 heteropoly acids in both HDS and HDN transformations at the same metal content. The highest activity in PAH hydrogenation is exhibited by the NiMoWS/Al2O3 catalyst prepared using H4SiMo3W9O40

Effect of quinoline on hydrodesulfurization and hydrogenation on bi- and trimetallic nimo(w)/al2o3 hydrotreating catalysts

International audienceThe effect of quinoline on the hydrodesulfurization and hydrogenation activities of bi- and trimetallic NiMo(W)/Al2O3 hydrotreating catalysts obtained using Keggin heteropoly acids H4SiMo3W9O40, H4SiMo12O40, and H4SiW12O40 (denoted as SiMo3W9, SiMo12, and SiW12, respectively) and a mixture of two monometallic heteropoly acids (SiMo12 and SiW12) was studied. The catalytic properties were determined in a fixed-bed microreactor in hydrotreating of model feedstock containing dibenzothiophene and naphthalene and of the same feedstock with the addition of quinoline. The trimetallic NiMoW/Al2O3 sample based on the mixed SiMo3W9 heteropoly acid exhibited 1.5 times higher catalytic activity in all the reactions studied compared to its analog prepared from a mixture of SiMo12 and SiW12 heteropoly acids with the same metal ratio. The trimetallic NiMoW/Al2O3 catalyst based on the mixed SiMo3W9 heteropoly acid surpassed in the activity the NiMo/Al2O3 sample and was more resistant to the inhibiting effect of quinoline than its analog prepared from a mixture of the two heteropoly acids. The correlations of the inhibiting effect of quinoline with the morphology of the active phase particles and the content of promoted active sites Ni(Mo)WS in the bi- and trimetallic NiMo(W)/Al2O3 catalysts were found

Enhancing the hydrodesulfurization of 4,6-dimethyldibenzothiophene through the use of mixed mows2 phase evidenced by haadf

International audienceMoW alumina supported hydrotreating (HDT) catalysts were synthesized by using mixed SiMonW12-n heteropolyacids (HPAs) and also from a mixture of SiMo12 and SiW12 HPAs with the same Mo/W ratios for reference. Gas phase sulfidation of the catalysts prepared from mixed MoW HPAs led to the formation of a mixed phase evidenced by high-angle annular dark-field (HAADF) images, where a core of Mo atoms was surrounded by W atoms. Contrariwise, most of MoS2 or WS2 slabs were observed in the solids prepared from a mixture of the HPAs. This mixed phase induced higher hydrodesulfurization (HDS) of DBT, as well as hydrogenation (HYD) of naphthalene, than it was observed in the case of the reference catalysts. Comparison of activation procedures (gas phase versus liquid phase) confirmed that sulfidation in gas phase led to more efficient catalysts, even in the case of the formation of the mixed slabs. Beneficial effect of the mixed MoWS phase was even more pronounced in the case of the HDS of a more refractory molecule, 4,6-dimethyldibenzothiophene (4,6-DMDBT), which was attributed to the more hydrogenating properties of this mixed phase

Activity of mo(w)s-2/sba-15 catalysts synthesized from simow heteropoly acids in 4,6-dimethyldibenzothiophene hydrodesulfurization

International audienceMo(W)/SBA-15 catalysts are prepared using heteropoly acids H4SiMo12O40, H4SiW12O40, and H4SiMo3W9O40. The catalysts in the sulfide form are studied by low-temperature nitrogen adsorption, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Catalytic properties are tested in the hydrodesulfurization of 4,6-dimethyldibenzothiophene. It is shown that the gas-phase sulfiding of Mo(W)/SBA-15 catalysts leads to increase in the average length of particles and the number of Mo(W)S2 layers in active phase particles compared with liquid-phase sulfiding with the use of dimethyl sulfide. The replacement of a quarter of tungsten atoms with molybdenum ones makes it possible to considerably improve the catalytic activity of the mixed catalyst Mo + W/SBA-15 compared with the monometallic counterparts. This effect can be enhanced due to the use of mixed heteropoly acid H4SiMo3W9O40 as a precursor of the active phase of the MoW/SBA-15 catalyst, which is apparently associated with the formation of MoWS2 active sites