Initial coke deposition on hydrotreating catalysts. Part II. Structure elucidation of initial coke on hydrodematallation catalysts

Hauser, A.; Stanislaus, A.; Marafi, Abdulazem; Al-Adwani, Awatef

doi:10.1016/j.fuel.2004.08.010

Cited by 57 publications

(40 citation statements)

References 40 publications

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“…During the first 6 days on stream after performance stabilization, between 90 and 95% of total final coke was deposited for feed A and between 80 and 85% for feed B. It is consistent with the literature ,, that claims that coke deposition initially increases rapidly before a pseudostable state is reached. For reforming catalysts, Querini et al and Absi-Halabi found that coke equivalent to 25% of the weight of the original catalyst is deposited within the first few hours of operation.…”

Section: Discussionsupporting

confidence: 90%

Impact of Feedstock Properties on the Deactivation of a Vacuum Gas Oil Hydrocracking Catalyst

et al. 2021

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The aim of this study was to understand the impact of vacuum gas oil (VGO) properties on the deactivation rate of a hydrocracking catalyst (nickel− molybdenum sulfide dispersed on a carrier containing USY zeolite). For this purpose, two hydrotreated feeds of different densities, organic nitrogen (∼120−150 ppmw) and aromatic content, were hydrocracked under operating conditions that favor catalyst deactivation, that is, high temperature (T = 418 °C) and high space velocity (LHSV = 3 h −1 ). The catalyst performance was followed by measuring the VGO conversion (370 °C+ petroleum cut) and determining the apparent kinetic constants for the main hydrocracking reactions (cracking, hydrodenitrogenation, hydrodesulfurization, and aromatics hydrogenation). The experiments were stopped after different times on stream (either 6 or 30 days) in order to assess the evolution of the catalyst as a function of time. The spent catalysts, obtained from three different reactor locations, were characterized by elemental and textural analyses and by thermogravimetry to investigate the quantity and nature of the coke formed. Catalytic tests with different model compounds (toluene and n-heptane) were carried out to determine the residual activity of the hydrogenating and acid catalyst functions. It was found that, at the evaluated conditions, both the nature and the content of organic nitrogen and aromatics compounds of the feedstock have a determinant role in the deactivation rate. Organic nitrogen determines the ratio between available metal and acid sites. The aromatics generate coke precursors on the available acid sites. Both factors play a coupled role that promotes coke deposition on the catalyst surface, which leads to an increase in the deactivation rate on top of the end boiling point of the feed.

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Section: Discussionsupporting

confidence: 90%

Impact of Feedstock Properties on the Deactivation of a Vacuum Gas Oil Hydrocracking Catalyst

et al. 2021

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“…The spectra of dried and ground samples were measured using proton gated decoupled single pulse excitation at high MAS (SPE/MAS) [16] and cross polarization with polarization inversion at low or moderate MAS (CP/PI/ MAS) [17]. For more details see Hauser et al [18]. As moderate MAS, 4 kHz (7 mm rotor) was chosen to minimize overlapping between the main signals (aliphatic and aromatic carbon) and the spinning side bands (SSB).…”

Section: Pilot Plant Experiments and Analysesmentioning

confidence: 99%

Investigation of the mechanism of sediment formation in residual oil hydrocracking process through characterization of sediment deposits

2005

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“…On the other hand, extensive studies have been made to clarify the deactivation mechanism of the catalyst for HDS of heavy oil (Christensen et al, 1994;Iijima et al, 1997;Gualda & Kasztelan, 1994;Furimsky & Massoth, 1999;Yamazaki et al, 1999;Fujii et al, 2000;Idei et al, 2002aIdei et al, ,b, 2003Ternan et al, 1979;Egiebor et al, 1989;Díez et al, 1990Díez et al, , 1992de Jong et al, 1991de Jong et al, , 1994Hadjiloizou et al, 1992;Zeuthen et al, 1994Zeuthen et al, , 1995Marafi & Stanislaus, 1997;Koide et al, 1999;Seki & Yoshimoto, 2001a,b,c,d;Kumata et al, 2001;Callejas et al, 2001;Higashi et al, 2002;Amemiya et al, 2003;Sahoo et al, 2004;Hauser et al, 2005;Eijsbouts & Inoue, 1994). Based on these studies, it has been suggested that catalyst deactivation is caused by (i) deposition of V and/or Ni sulfides originated from metalloporphyrin compounds in heavy oil (Christensen et al, 1994;Iijima et al, 1997;Gualda & Kasztelan, 1994;Furimsky & Massoth, 1999;Yamazaki et al, 1999;Fujii et al, 2000;Idei et al, 2002aIdei et al, ,b, 2003, (ii) deposition of carbonaceous compounds (Gualda & Kasztelan, 1994;Furimsky & Massoth, 1999;…”

Section: Introductionmentioning

confidence: 99%

Quasiin situNiK-edge EXAFS investigation of the spent NiMo catalyst from ultra-deep hydrodesulfurization of gas oil in a commercial plant

et al. 2010

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Ni species on the spent NiMo catalyst from ultra-deep hydrodesulfurization of gas oil in a commercial plant were studied by Ni K-edge EXAFS and TEM measurement without contact of the catalysts with air. The Ni-Mo coordination shell related to the Ni-Mo-S phase was observed in the spent catalyst by quasi in situ Ni K-edge EXAFS measurement with a newly constructed high-pressure chamber. The coordination number of this shell was almost identical to that obtained by in situ Ni K-edge EXAFS measurement of the fresh catalyst sulfided at 1.1 MPa. On the other hand, large agglomerates of Ni(3)S(2) were observed only in the spent catalyst by quasi in situ TEM/EDX measurement. MoS(2)-like slabs were sintered slightly on the spent catalyst, where they were destacked to form monolayer slabs. These results suggest that the Ni-Mo-S phase is preserved on the spent catalyst and Ni(3)S(2) agglomerates are formed by sintering of Ni(3)S(2) species originally present on the fresh catalyst.

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Initial coke deposition on hydrotreating catalysts. Part II. Structure elucidation of initial coke on hydrodematallation catalysts

Cited by 57 publications

References 40 publications

Impact of Feedstock Properties on the Deactivation of a Vacuum Gas Oil Hydrocracking Catalyst

Impact of Feedstock Properties on the Deactivation of a Vacuum Gas Oil Hydrocracking Catalyst

Investigation of the mechanism of sediment formation in residual oil hydrocracking process through characterization of sediment deposits

Quasiin situNiK-edge EXAFS investigation of the spent NiMo catalyst from ultra-deep hydrodesulfurization of gas oil in a commercial plant

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