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hydrotreating catalysts based on activated

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  • Applied Catalysis A: General 441 442 (2012) 99 107

    Contents lists available at SciVerse ScienceDirect

    Applied Catalysis A: General

    j ourna l ho me page: www.elsev ier .com

    Prepar taderived

    Yu Shia, reka Natural Resoub National Insti e, Edm

    a r t i c l

    Article history:Received 19 May 2012Received in revised form 13 July 2012Accepted 14 July 2012Available online 20 July 2012

    Keywords:Oil sand petroActivated carbHydrotreatingHeavy vacuum

    Novel NiMo/activated carbon (AC) hydrotreating catalysts were prepared and evaluated for upgradingheavy vacuum gas oil (HVGO). The AC supports were derived from Alberta oil sand petroleum coke, i.e.uid coke and/or delayed coke, hereafter referred to as OSP coke, through a chemical process. The BETsurface area was as high as 2194 m2/g for the uid coke derived AC and 2357 m2/g for the delayed cokederived AC. Both ACs contained a large number of micropores with pore volume as high as 1.2 cm3/g. Ni

    1. Introdu

    As the wand more sgies to proc[1]. Catalytconventionsulfur, nitrodium) in hehave to be pace with

    CorresponE-mail add

    0926-860X/$ http://dx.doi.oleum (OSP) cokeon (AC)

    gas oil (HVGO)

    and Mo based active component precursors could be easily loaded on the activated carbon supports bychemical impregnation of nickel nitrate and ammonium molybdate followed by calcination in nitrogenat 773 K without further modication or oxidation treatment to the activated carbons. Scanning electronmicroscopy (SEM) observation showed highly porous surface structure of the bare activated carbon sup-ports and well dispersed metal (oxide) precursor nanoparticles of 3050 nm loaded on the AC supports.For comparison, two reference catalysts were also prepared by the same procedure but using commercialactivated carbon and porous alumina as supports. After catalyst activation by sulding, the hydrotreatingperformance of the prepared catalysts was evaluated in a magnetically stirred autoclave with a HVGOfeedstock to examine their hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities. Twocommercial hydrotreating catalysts were also tested and compared under similar conditions with thesame feed. The results showed that the catalysts based on the activated carbon supports prepared fromOSP coke had better hydrotreating performance than the other catalysts. Scanning transmission elec-tron microscopy (STEM) characterization of the catalysts after activation showed that small particles ofnanostructure (25 nm in size) were evenly embedded in the carbon matrix except for some bigger par-ticles that were located on the catalyst surface. Energy dispersive X-ray (EDX) spectroscopy revealed thatthese particles were composed of Ni, Mo and S elements. The dispersed nanoparticles formed the activesites and were responsible for the observed high HDS and HDN activity. Elemental analysis and surfacecharacterization of the spent catalysts showed that the formation of coke precursors was favored on thealumina supported catalyst, which resulted in catalyst deactivation.

    Crown Copyright 2012 Published by Elsevier B.V. All rights reserved.

    ction

    orld remaining accessible crude oil become heavierour, there is an urgent need for improved technolo-ess such crudes to produce clean transportation fuelsic hydroprocessing technology is well established inal reneries worldwide. Due to the high contents ofgen, asphaltenes and heavy metals (nickel and vana-avy feedstocks [2], existing catalysts and technologiesmodied or new ones have to be developed to keepmore stringent environmental regulations, including

    ding author. Tel.: +1 780 987 8703; fax: +1 780 987 5349.ress: YuShi@dal.ca (Y. Shi).

    emissions from hydrocarbon fuel use, such as SOx, NOx, and CO2[3,4]. Hydrotreating catalysts are used in reneries to catalyticallyremove S, N and metals, and to saturate aromatic compounds. Cur-rently, alumina-supported hydrotreating catalysts are commonlyused because of the good mechanical and textural specics of alu-mina [5,6]. However, suldation of alumina supported metal oxidesis always incomplete due to the strong metalsupport interactions(SMSI) present in the catalyst suldation step, which is a signif-icant drawback of alumina [79]. In addition, alumina supportedcatalysts suffer from deactivation caused by coking and nitrogencompounds, and heavy metal deposition when heavy oil is treated[2,1014]. In the past decades much effort has been paid eitherto modify existing catalysts by developing new synthesis meth-ods through addition of new promoting species, or to develop newsupports based catalysts to improve hydrotreating performance forheavy feedstocks [1520].

    see front matter Crown Copyright 2012 Published by Elsevier B.V. All rights reserved.rg/10.1016/j.apcata.2012.07.014ation and evaluation of hydrotreating ca from oil sand petroleum coke

    , Jinwen Chena, Jian Chenb, Robb A. Macleodb, Marces Canada, CanmetENERGY-Devon, One Oil Patch Drive, Devon, AB, T9G 1A8, Canadatute for Nanotechnology, National Research Council Canada, 11421 Saskatchewan Driv

    e i n f o a b s t r a c t/ locate /apcata

    lysts based on activated carbon

    Malacb

    onton, AB, T6G 2M9, Canada

  • 100 Y. Shi et al. / Applied Catalysis A: General 441 442 (2012) 99 107

    Activated carbon (AC) possesses high microporosity and sur-face area. It has attracted considerable attention recently as apossible candidate for replacing conventional alumina support forupgrading heavy gas oil [2,2123]. Activated carbon supportedhydrotreatipounds, gometal comp-Al2O3 forPrevious stities towarCoMo hydbeen wideling hydrodby applyinhybridizatiosolely as catains muchduring sulport surfacactive sitesimportant flow producsupport andlyst provide

    Recentlyreported bprocesses, converting into porousporosity [32S (>6 wt%) aand applicathe AC can plyst supporprecious meMo(W)S hywith sulfur alyst precurthe activati

    Althougare favorablow mechanthe potentimean time face functiowill continualyst suppofeasibility oactivated cahydroproceas the testlysts and thconductingsupported cmercial hyd

    2. Experim

    2.1. Materi

    Dry uiddirectly wicommerciapany, Inc. mesh) as t

    mesoporous commercial -Al2O3 (PURALOX HP 14/150) pow-der was provided by Sasol Germany GmbH and used as anotherreference catalyst support without any treatment. Since HVGOwas used as feed in this study to evaluate catalyst activity, the

    orouvity wo red frS grion ac Ctivatde (Dr DMum

    tivat

    h cokoces

    wasto mg. ThOH/crredo a qmin. e of

    agae of ctivas waater nt atvernd cok

    den

    talys

    Mo/Ass mAC ay preniumpecinatef 35

    K foing atraticoncand er thpar

    talys

    C/H/ke sere

    and he saent

    m atm fong catalysts also have less sensitivity to nitrogen com-od resistance to coke deposition and easy recovery ofonents from spent catalysts, giving it advantages over

    processing heavy petroleum feedstocks [13,2325].udies have demonstrated good hydrotreatment activ-d sulfur removal with AC supported Mo, NiMo orrotreating catalysts [2426]. However they have noty applied in commercial operations. Other promis-esulfurization (HDS) results were also reported eitherg activated carbon (or mesoporous carbon) throughn with alumina support or by using activated carbontalyst support [19,2628]. Since activated carbon con-

    less polar oxygen containing species than alumina,dation, the much weaker interaction between the sup-e and metals favors the formation of the Type II high

    (NiMoS II) [2931]. Furthermore, since cost is anactor in catalyst selection for reneries, the relativelytion cost of activated carbon as hydrotreating catalyst

    easy recovery of metals by burning off the spent cata- additional advantages., although activation of petroleum coke has beeny several research groups with different activationno efcient method has yet been demonstrated forAlberta OSP coke (both uid coke and delayed coke)

    carbon materials with relatively high surface area and36]. Since OSP coke contains more impurities, such asnd heavy metals, than conventional coke, the activationtion of it are more challenging [10,37]. Sulfur content inotentially limit its application as a hydrogenation cata-

    t for supporting active metal components, especially fortals. On the contrary, transition metal sulde Ni(Co)S ordroprocessing catalysts usually require pre-suldationcontaining compounds (such as H2S) to activate the cat-sor. Therefore, sulfur is helpful, rather than harmful, inon process of this type of hydrotreating catalysts.h activated carbon has a number of properties whichle for hydrotreating heavy petroleum feedstocks, itsical strength and weak surface functionality might be

    al hurdles for industrial/commercial application. In thealumina, due to its high mechanical strength and sur-nality, and mature commercial production technology,e to be the dominating commercial hydrotreating cat-rt in the foreseeable future. This paper explores thef developing low cost hydrotreating catalysts based onrbon derived from Alberta OSP coke and examines theirssing performance using heavy vacuum gas oil (HVGO)ing feed. The catalytic activity of the prepared cata-e effects of catalyst support have been evaluated by

    comparative performance tests with a commercial ACatalyst, an alumina supported catalyst, and two com-rotreating catalysts supported on -Al2O3.

    ental

    als

    coke (F-coke) and delayed coke (D-coke) were used

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