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dc.contributor.authorAl-Sabban, Bedour E.
dc.contributor.authorFalivene, Laura
dc.contributor.authorKozlov, Sergey M.
dc.contributor.authorAguilar Tapia, Antonio
dc.contributor.authorOuld-Chikh, Samy
dc.contributor.authorHazemann, Jean-Louis
dc.contributor.authorCavallo, Luigi
dc.contributor.authorBasset, Jean-Marie
dc.contributor.authorTakanabe, Kazuhiro
dc.date.accessioned2017-05-09T08:34:34Z
dc.date.available2017-05-09T08:34:34Z
dc.date.issued2017-05-02
dc.identifier.citationAlSabban B, Falivene L, Kozlov SM, Aguilar-Tapia A, Ould-Chikh S, et al. (2017) In-operando elucidation of bimetallic CoNi nanoparticles during high-temperature CH 4 /CO 2 reaction. Applied Catalysis B: Environmental. Available: http://dx.doi.org/10.1016/j.apcatb.2017.04.076.
dc.identifier.issn0926-3373
dc.identifier.doi10.1016/j.apcatb.2017.04.076
dc.identifier.urihttp://hdl.handle.net/10754/623410
dc.description.abstractDry reforming of methane (DRM) proceeds via CH4 decomposition to leave surface carbon species, followed by their removal with CO2-derived species. Reactivity tuning for stoichiometric CH4/CO2 reactants was attempted by alloying the non-noble metals Co and Ni, which have high affinity with CO2 and high activity for CH4 decomposition, respectively. This study was focused on providing evidence of the capturing surface coverage of the reactive intermediates and the associated structural changes of the metals during DRM at high temperature using in-operando X-ray absorption spectroscopy (XAS). On the Co catalysts, the first-order effects with respect to CH4 pressure and negative-order effects with respect to CO2 pressure on the DRM rate are consistent with the competitive adsorption of the surface oxygen species on the same sites as the CH4 decomposition reaction. The Ni surface provides comparatively higher rates of CH4 decomposition and the resultant DRM than the Co catalyst but leaves some deposited carbon on the catalyst surface. In contrast, the bimetallic CoNi catalyst exhibits reactivity towards the DRM but with kinetic orders resembling Co catalyst, producing negligible carbon deposition by balancing CH4 and CO2 activation. The in-operando X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements confirmed that the Co catalyst was progressively oxidized from the surface to the bulk with reaction time, whereas CoNi and Ni remained relatively reduced during DRM. Density functional theory (DFT) calculation considering the high reaction temperature for DRM confirmed the unselective site arrangement between Co and Ni atoms in both the surface and bulk of the alloy nanoparticle (NP). The calculated heat of oxygen chemisorption became more exothermic in the order of Ni, CoNi, Co, consistent with the catalytic behavior. The comprehensive experimental and theoretical evidence provided herein clearly suggests improvement to the catalyst design protocol by selecting the appropriate composition of Co-Ni alloy.
dc.description.sponsorshipThis work was funded by Saudi Arabia Basic Industries Corporation (SABIC) through a collaborative research project with King Abdullah University of Science and Technology (KAUST). The authors gratefully thank Dr. Lawrence D’Souza (SABIC) for technical advice and valuable contributions. Moreover, the authors acknowledge Mr. Dong-Chang Kang, KAUST Catalysis Center, and Dr. Manuel A. Roldan-Gutierrez, KAUST Core Laboratories, for their assistance with the DRIFTS and TEM measurements, respectively. We are also grateful for the computational resources for the XAS spectra acquired from the KAUST Supercomputing Laboratory using the supercomputer Shaheen II under project k1016.
dc.publisherElsevier BV
dc.relation.urlhttp://www.sciencedirect.com/science/article/pii/S0926337317303909
dc.rightsUnder a Creative Commons license
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subjectDry Reforming of Methane
dc.subjectNickel
dc.subjectCobalt
dc.subjectBimetal
dc.subjectCarbon Deposition
dc.subjectKinetics
dc.subjectDensity Functional Theory
dc.subjectIn-operando X-ray Absorption Spectroscopy
dc.titleIn-operando elucidation of bimetallic CoNi nanoparticles during high-temperature CH 4 /CO 2 reaction
dc.typeArticle
dc.contributor.departmentKAUST Catalysis Center (KCC)
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Division
dc.identifier.journalApplied Catalysis B: Environmental
dc.eprint.versionPost-print
dc.contributor.institutionInstitut Néel, UPR 2940 CNRS, 38042 Grenoble Cedex 9, France
kaust.personAl-Sabban, Bedour E.
kaust.personFalivene, Laura
kaust.personKozlov, Sergey M.
kaust.personAguilar Tapia, Antonio
kaust.personOuld-Chikh, Samy
kaust.personCavallo, Luigi
kaust.personBasset, Jean-Marie
kaust.personTakanabe, Kazuhiro
refterms.dateFOA2018-06-13T18:55:58Z


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