Spinel-structured ZnCr2O4 with excess Zn is the active ZnO/Cr2O3 catalyst for high-temperature methanol synthesis

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dc.contributor.author Song, Huiqing
dc.contributor.author Laudenschleger, Daniel
dc.contributor.author Carey, John J.
dc.contributor.author Ruland, Holger
dc.contributor.author Nolan, Michael
dc.contributor.author Muhler, Martin
dc.date.accessioned 2017-11-02T09:58:42Z
dc.date.available 2017-11-02T09:58:42Z
dc.date.issued 2017-09-27
dc.identifier.citation Song, H., Laudenschleger, D., Carey, J. J., Ruland, H., Nolan, M. and Muhler, M. (2017) 'Spinel-Structured ZnCr2O4 with Excess Zn Is the Active ZnO/Cr2O3 Catalyst for High-Temperature Methanol Synthesis', ACS Catalysis, pp. 7610-7622. doi: 10.1021/acscatal.7b01822 en
dc.identifier.volume 7 en
dc.identifier.startpage 7610 en
dc.identifier.endpage 7622 en
dc.identifier.issn 2155-5435
dc.identifier.uri http://hdl.handle.net/10468/4945
dc.identifier.doi 10.1021/acscatal.7b01822
dc.description.abstract A series of ZnO/Cr2O3 catalysts with different Zn:Cr ratios was prepared by coprecipitation at a constant pH of 7 and applied in methanol synthesis at 260–300 °C and 60 bar. The X-ray diffraction (XRD) results showed that the calcined catalysts with ratios from 65:35 to 55:45 consist of ZnCr2O4 spinel with a low degree of crystallinity. For catalysts with Zn:Cr ratios smaller than 1, the formation of chromates was observed in agreement with temperature-programmed reduction results. Raman and XRD results did not provide evidence for the presence of segregated ZnO, indicating the existence of Zn-rich nonstoichiometric Zn–Cr spinel in the calcined catalyst. The catalyst with Zn:Cr = 65:35 exhibits the best performance in methanol synthesis. The Zn:Cr ratio of this catalyst corresponds to that of the Zn4Cr2(OH)12CO3 precursor with hydrotalcite-like structure obtained by coprecipitation, which is converted during calcination into a nonstoichiometric Zn–Cr spinel with an optimum amount of oxygen vacancies resulting in high activity in methanol synthesis. Density functional theory calculations are used to examine the formation of oxygen vacancies and to measure the reducibility of the methanol synthesis catalysts. Doping Cr into bulk and the (10–10) surface of ZnO does not enhance the reducibility of ZnO, confirming that Cr:ZnO cannot be the active phase. The (100) surface of the ZnCr2O4 spinel has a favorable oxygen vacancy formation energy of 1.58 eV. Doping this surface with excess Zn charge-balanced by oxygen vacancies to give a 60% Zn content yields a catalyst composed of an amorphous ZnO layer supported on the spinel with high reducibility, confirming this as the active phase for the methanol synthesis catalyst. en
dc.description.sponsorship Science Foundation Ireland (SFI funded computational resources at Tyndall and at the Irish Centre for High End Computing (ICHEC)); European Cooperation in Science and Technology (COST action CM1104) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher American Chemical Society en
dc.rights © 2017 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/pdf/10.1021/acscatal.7b01822 en
dc.subject DFT+U en
dc.subject Methanol synthesis en
dc.subject Nonstoichiometric spinel en
dc.subject Oxygen vacancy en
dc.subject ZnO/Cr2O3 en
dc.title Spinel-structured ZnCr2O4 with excess Zn is the active ZnO/Cr2O3 catalyst for high-temperature methanol synthesis en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Michael Nolan, Tyndall Theory Modelling & Design Centre, University College Cork, Cork, Ireland. +353-21-490-3000 Email: michael.nolan@tyndall.ie en
dc.internal.availability Full text available en
dc.check.info Access to this article is restricted for 12 months after publication by request of the publisher. en
dc.check.date 2018-09-27
dc.date.updated 2017-11-02T09:49:58Z
dc.description.version Accepted Version en
dc.internal.rssid 417268007
dc.contributor.funder Seventh Framework Programme en
dc.contributor.funder European Cooperation in Science and Technology en
dc.contributor.funder Science Foundation Ireland en
dc.description.status Peer reviewed en
dc.identifier.journaltitle ACS Catalysis en
dc.internal.copyrightchecked No !!CORA!! en
dc.internal.licenseacceptance Yes en
dc.internal.IRISemailaddress michael.nolan@tyndall.ie en
dc.relation.project info:eu-repo/grantAgreement/EC/FP7::SP1::NMP/604296/EU/Catalytic Partial Oxidation of Bio Gas and Reforming of Pyrolysis Oil (Bio Oil) for an Autothermal Synthesis Gas Production and Conversion into Fuels/BIOGO-FOR-PRODUCTION en

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