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Mexico City, Mexico

Leyva C.,Mexican Institute of Petroleum | Ancheyta J.,Mexican Institute of Petroleum | Travert A.,University of Caen Lower Normandy | Mauge F.,University of Caen Lower Normandy | And 3 more authors.
Applied Catalysis A: General | Year: 2012

NiMo/SiO 2-Al 2O 3 mixed oxide supported catalysts were investigated for hydroprocessing of heavy crude oil at moderate reaction conditions. Hydrodesulfurization (HDS), hydrodemetalization (HDM), hydrodeasphaltenization (HDAs) and hydrodenitrogenation (HDN) reactions were studied as function of time-on-stream (TOS). The results indicated that HDS of crude oil corresponds to the number of active metal sites (sulfide phases) present in the catalyst, HDN is enhanced when the catalyst presents a combination of well dispersed sulfide phases and weak to moderate acidity. HDM presented a complex behavior indicating that it is affected significantly not only by the dispersion of the sulfide phase but also by the porosity and acidity of the catalyst. As expected, for HDAs both acidity and textural properties are important. The stability of the catalyst with time-on-stream was affected by coke and metals deposition. The supports and fresh catalysts were characterized by nitrogen physisorption, SEM-EDX, and FT-IR of CO and pyridine adsorption. The results confirm that NiMo/SiO 2-Al 2O 3 catalysts are a good option for the hydrotreatment of heavy oils and that the method used here for support preparation can tune the formation of meso- or macro-porosity and the type and strength of the catalyst acid sites. © 2012 Elsevier B.V. Source

Ortiz-Moreno H.,UNICAT | Ramirez J.,UNICAT | Sanchez-Minero F.,National Polytechnic Institute of Mexico | Cuevas R.,UNICAT | Ancheyta J.,Mexican Institute of Petroleum
Fuel | Year: 2014

The effect of the catalyst load in slurry hydrocracking of heavy Maya crude oil was investigated at mild conditions (390 °C and 1400 H2 psi).The catalyst load and operating time were varied in the intervals 0-1000 ppm Mo and 0-11 h respectively. The results allowed to establish the transformation routes of the different fractions under thermal or catalytic conditions. Under thermal conditions, the contributors to gas formation were found to be: Asphaltenes. Source

Rayo P.,Mexican Institute of Petroleum | Ramirez J.,Mexican Institute of Petroleum | Torres-Mancera P.,UNICAT | Marroquin G.,Mexican Institute of Petroleum | And 2 more authors.
Fuel | Year: 2012

In the present work we analyze the changes in hydrocracking, hydrodesulfurization, hydrodeasphaltenization, and hydrodesmetallization, during the hydrotreating of Maya crude, when 3.4 wt.% of P 2O 5 is incorporated by two different routes to a NiMo/Al 2O 3 catalyst. The catalysts were characterized by nitrogen physisorption, XRD, HRTEM, SEM, and CO adsorption analyzed by FTIR. Additionally, to obtain deeper knowledge on the reaction system, the catalysts were also tested in the HDS of 4,6-DMDBT, and hydrocracking of cumene. NiMo/PAl 2O 3 shows the highest HDS activity for 4,6-DMDBT, the better hydrogenating properties, and the best performance in all the reactions during hydrotreating of Maya crude. The acidity and porosity of the catalyst are determinant factor for the conversion of atmospheric residue. At similar acidity, the porosity defines the best catalyst and conversely, at similar porosity, acidity will define the activity of the catalyst. However, an excess of acidity in the catalyst can lead to rapid deactivation. NiMo/PAl 2O 3 displays superior performance compared to NiMo/Al 2O 3 and NiMoP/Al 2O 3 because it presents the best combination of acidity, porosity and distribution of the sulfided Ni and Mo phases, which provide the hydrodesulfurization and hydrogenating functions. © 2012 Elsevier Ltd. All rights reserved. Source

Ramirez J.,UNICAT | Gutierrez-Alejandre A.,UNICAT | Sanchez-Minero F.,National Polytechnic Institute of Mexico | MacIas-Alcantara V.,UNICAT | And 4 more authors.
Energy and Fuels | Year: 2012

HDS of 4,6-DMDBT over NiMoP/SBA-15 and NiMoP/(x)TiSBA-15 catalysts prepared using an heteropolyacid (H 3PMo 12O 40) and nickel citrate (C 12H 10Ni 3O 14) as Mo and Ni precursors was studied. To analyze the effect of calcination temperature on HDS activity, catalysts noncalcined and calcined at 773 K were prepared. The performance of the different catalysts during the hydrodesulfurization of 4,6-dimethyldibenzothiophene was compared with that of a reference catalyst prepared by impregnation with a solution containing ammonium heptamolybdate and nickel nitrate. Kinetic parameters for the HDS of 4,6-DMDBT were estimated using a simplified kinetic model. The catalysts were characterized by N 2 physisorption, X-ray diffraction, Raman, and IR of adsorbed CO at ∼100 K. The results show that for catalysts supported on pure SBA-15 the noncalcined catalyst prepared with H 3PMo 12O 40 (NiMoP(H-nc)/SBA-15) presents the highest number of active sites, the higher apparent reaction rate constant for the hydrogenation route, and therefore the best 4,6-DMDBT HDS activity. In contrast, for Ti-modified catalysts, NiMoP/(x)Ti-SBA-15, the highest HDS activity was found when 15% of TiO 2 was incorporated to SBA-15 and the catalyst was calcined at 773 K. This catalyst presented the highest TOF. © 2011 American Chemical Society. Source

Infrared spectroscopy of adsorbed CO and HDS activity for thiophene, dibenzothiophene, and 4,6-dimethyl dibenzothiophene were performed using Mo/Al 2O 3, CoMo/Al 2O 3, and CoMo-EDTA/Al 2O 3 catalysts. The results show differences between the FT-IR absorption coefficients of CO adsorbed on Co-Mo-S sites for CoMo/Al 2O 3, and CoMo-EDTA/Al 2O 3, despite that the vibration frequency of the CO - Co-Mo-S peak in both cases is observed at ∼2071 cm -1. The absorption coefficient is bigger when the level of promotion increases. We propose that the increased absorption coefficient is associated with the change in the local structure of the surface Co sites from tetrahedral/pseudo-tetrahedral, in partially promoted crystallites, to square planar structure in totally promoted zones of MoS 2 crystallites. For simple molecules like thiophene, the HDS activity does not change if Co is in either tetrahedral/pseudo-tetrahedral or square planar structures. In contrast, an open structure like square planar Co favors the accessibility of 4,6-DMDBT to the Co-Mo-S sites, increasing its HDS activity. © 2012 Elsevier Inc. All rights reserved. Source

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