TY - JOUR

T1 - Hydroprocessing of Maya vacuum residue using a NiMo catalyst supported on Cr-doped alumina

AU - Puron, Holda

AU - Pinilla, Jose Luis

AU - Saraev, Andrey A.

AU - Kaichev, Vasily V.

AU - Millan, Marcos

N1 - Publisher Copyright: © 2019 Elsevier Ltd Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - Mesoporous alumina was doped with Cr using a co-precipitation method to prepare a support for hydrocracking catalysts. Ni and Mo were then impregnated on Cr-doped mesoporous alumina (NiMo/Al2O3-Cr). Catalytic activity was tested in hydrodeasphaltenisation (HDA), hydrodesulfurisation (HDS) and hydrodemetallisation (HDM) of Maya vacuum residue in a batch reactor and compared with NiMo supported on mesoporous alumina not doped with Cr (NiMo/Al2O3). Following activation and initial carbon deposition, experiments involving contact of the catalysts with fresh feed were performed. Greater HDA extent and maltene to asphaltene ratios were obtained with NiMo/Al2O3-Cr than NiMo/Al2O3 despite a larger amount of coke deposits. Significant activity of both NiMo/Al2O3-Cr and NiMo/Al2O3 towards HDS and HDM were also observed. Alumina textural properties remained relatively unaffected by the co-precipitation of Cr. X-ray photoelectron spectroscopy (XPS) showed that the catalysts contained Cr3+ and after reduction all Ni was present in metallic state at least in the near-surface region, while Mo6+ was reduced to Mo4+ and Moδ+ (0 ≤ δ ≤ 3) to a larger extent in NiMo/Al2O3-Cr. Lower reduction temperatures in the presence of Cr were determined, suggesting a larger number of metal sites available in reduced form at operating conditions. It was found that Cr aided metal dispersion in catalyst synthesis and coke dispersion during reaction. Spent catalysts showed reductions in surface area and pore volume. However, while spent NiMo/Al2O3 catalysts had a decrease in average pore diameter (APD), NiMo/Al2O3-Cr maintained the fresh material APD, which may explain the sustained catalytic activity.

AB - Mesoporous alumina was doped with Cr using a co-precipitation method to prepare a support for hydrocracking catalysts. Ni and Mo were then impregnated on Cr-doped mesoporous alumina (NiMo/Al2O3-Cr). Catalytic activity was tested in hydrodeasphaltenisation (HDA), hydrodesulfurisation (HDS) and hydrodemetallisation (HDM) of Maya vacuum residue in a batch reactor and compared with NiMo supported on mesoporous alumina not doped with Cr (NiMo/Al2O3). Following activation and initial carbon deposition, experiments involving contact of the catalysts with fresh feed were performed. Greater HDA extent and maltene to asphaltene ratios were obtained with NiMo/Al2O3-Cr than NiMo/Al2O3 despite a larger amount of coke deposits. Significant activity of both NiMo/Al2O3-Cr and NiMo/Al2O3 towards HDS and HDM were also observed. Alumina textural properties remained relatively unaffected by the co-precipitation of Cr. X-ray photoelectron spectroscopy (XPS) showed that the catalysts contained Cr3+ and after reduction all Ni was present in metallic state at least in the near-surface region, while Mo6+ was reduced to Mo4+ and Moδ+ (0 ≤ δ ≤ 3) to a larger extent in NiMo/Al2O3-Cr. Lower reduction temperatures in the presence of Cr were determined, suggesting a larger number of metal sites available in reduced form at operating conditions. It was found that Cr aided metal dispersion in catalyst synthesis and coke dispersion during reaction. Spent catalysts showed reductions in surface area and pore volume. However, while spent NiMo/Al2O3 catalysts had a decrease in average pore diameter (APD), NiMo/Al2O3-Cr maintained the fresh material APD, which may explain the sustained catalytic activity.

KW - Asphaltene

KW - Cr-doped alumina

KW - Hydrocracking

KW - Hydroprocessing

KW - NiMo catalyst

KW - Vacuum residue

KW - MOLYBDENUM

KW - TEMPERATURE-PROGRAMMED-REDUCTION

KW - X-RAY PHOTOELECTRON

KW - HYDROCRACKING

KW - MESOPOROUS ALUMINA

KW - XPS

KW - OXIDATIVE DEHYDROGENATION

KW - PILLARED CLAYS

KW - SURFACE-CHEMISTRY

KW - PORE-STRUCTURE

UR - http://www.scopus.com/inward/record.url?scp=85076613946&partnerID=8YFLogxK

U2 - 10.1016/j.fuel.2019.116717

DO - 10.1016/j.fuel.2019.116717

M3 - Article

AN - SCOPUS:85076613946

VL - 263

JO - Fuel

JF - Fuel

SN - 0016-2361

M1 - 116717

ER -