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Physical and chemical behaviour of tungsten oxide in the presence of nickel additive under hydrogen and carbon monoxide atmospheres

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dc.contributor.authorSalleh F.en_US
dc.contributor.authorTahari M.N.A.en_US
dc.contributor.authorSamsuri A.en_US
dc.contributor.authorSaharuddin T.S.T.en_US
dc.contributor.authorSulhadi S.S.en_US
dc.contributor.authorYarmo M.A.en_US
dc.date.accessioned2024-05-29T02:05:32Z
dc.date.available2024-05-29T02:05:32Z
dc.date.issued2020
dc.description.abstractThe physical and chemical behaviour of bulk tungsten oxide (WO3) and Ni doped tungsten oxide (15% Ni/WO3) were examined by performing a temperature-programmed reduction (TPR) technique. The chemical composition, morphology, and surface composition of both samples before and after reduced were analysed by X-ray diffraction (XRD), scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) analysis. The XRD pattern of calcined Ni doped tungsten oxide powder comprised of WO3 and nickel tungstate (NiWO4) phases. The reduction behaviour was investigated by a non-isothermal reduction up to 900 °C achieved under (10 and 20% v/v) hydrogen in nitrogen (H2 in N2) and (20 and 40% v/v) carbon monoxide in nitrogen (CO in N2) atmospheres. The H2-TPR were indicated the reduction of bulk WO3 and 15% NiWO3 proceed in three steps (WO3 → WO2 → WO2 + W) and (WO3 → WO2 → W + Ni4W) respectively under 20% H2. Whereas, the reduction of 15% WO3 under 40% CO involves of two following stages: (i) low temperature (<800 °C) transformation of WO3 → WO2.72 → WO2 and, (ii) high temperature (>800 °C) transformation of WO2 → W → WC. Furthermore, NiWO4 alloy phase was transformed according to the sequence NiWO4 → Ni + WO2.72 → Ni + WO2 → Ni + W → Ni4W + W at temperature >700 °C and >800 °C in H2 and CO atmospheres, respectively. It can be concluded that the reduction behaviour of WO3 is matched with the thermodynamic data. In addition, the reduction under H2 is more favourable and have better reducibility compared to the CO gas. It is due to the small molecule size and molecule mass of H2 that encourages the diffusion of H2 molecule into the internal surface of the catalyst compared to CO. Moreover, Ni additive had improved the WO3 reducibility and enhancing the CO adsorption and promotes the formation of tungsten carbide (WC) by carburisation reaction. Besides, the formation of Ni during the reduction of 15% Ni/WO3 under CO reductant catalysed the Boudouard reaction to occur, which disproportionated the carbon monoxide to carbon dioxide and carbon (CO → CO2 + C). © 2020 Hydrogen Energy Publications LLCen_US
dc.identifier.doi10.1016/j.ijhydene.2020.08.099
dc.identifier.issn3603199
dc.identifier.scopus2-s2.0-85092188365
dc.identifier.urihttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85092188365&doi=10.1016%2fj.ijhydene.2020.08.099&partnerID=40&md5=56706a546b32660d00dd4927b5af11fd
dc.identifier.urihttps://oarep.usim.edu.my/handle/123456789/10334
dc.languageEnglish
dc.language.isoen_USen_US
dc.publisherElsevier Ltden_US
dc.relation.ispartofChemical Papersen_US
dc.sourceScopus
dc.subjectCarbideen_US
dc.subjectCarbon monoxideen_US
dc.subjectHydrogenen_US
dc.subjectNickelen_US
dc.subjectTPRen_US
dc.subjectTungsten oxideen_US
dc.titlePhysical and chemical behaviour of tungsten oxide in the presence of nickel additive under hydrogen and carbon monoxide atmospheresen_US
dc.typeArticleen_US
dspace.entity.typePublication

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