Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry

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dc.contributor.authorMaphutha, Malebelo
dc.contributor.authorde Oliveira, Dominic
dc.contributor.authorNyathi, Thulani M
dc.contributor.authorFadlalla, Mohamed I
dc.contributor.authorHenkel, Robert
dc.contributor.authorFischer, Nico
dc.contributor.authorClaeys, Michael
dc.date.accessioned2021-10-13T09:33:55Z
dc.date.available2021-10-13T09:33:55Z
dc.date.issued2021-05-16
dc.date.updated2021-05-24T15:04:25Z
dc.description.abstractThe presented study investigated the effects of temperature (350–650 ◦C) and gas environment (pure Ar versus a H2O/H2 partial pressure ratio (PH2O/PH2) of 5) on the extent of sintering and oxidation of Al2O3 -supported Ni0 nanoparticles (≈4 nm). We note that a PH2O/PH2 of 5 corresponds to a simulated CO conversion of 94% during methanation. Sintering and oxidation were studied using in situ magnetometry, while ex situ TEM analyses confirmed the particle sizes before and after the magnetometry-based experiments. It was found that increasing the temperature from 350 to 650 ◦C in Ar at atmospheric pressure causes a negligible change to the average size and degree of reduction (DOR) of the starting Ni0 nanoparticles. However, studying the same temperature window under hydrothermal conditions at 10 bar causes significant particle growth (≈9 nm) and the development of a bimodal distribution. Furthermore, the presence of steam decreases the DOR of Ni0 from 86.2% after initial activation to 22.2% due to oxidation. In summary, this study reports on the expected sintering and oxidation of Ni-based catalysts under high CO conversion conditions at elevated temperatures during methanation. Importantly, we were able to demonstrate how magnetometry-based analyses can provide similar size information (and changes thereof) as those observed with TEM but with the added advantage that this information can be obtained in situ.en_US
dc.identifier10.3390/catal11050636
dc.identifier.apacitationMaphutha, M., de Oliveira, D., Nyathi, T. M., Fadlalla, M. I., Henkel, R., Fischer, N., & Claeys, M. (2021). Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry. <i>Catalysts</i>, 11(5), 636. http://hdl.handle.net/11427/35226en_ZA
dc.identifier.chicagocitationMaphutha, Malebelo, Dominic de Oliveira, Thulani M Nyathi, Mohamed I Fadlalla, Robert Henkel, Nico Fischer, and Michael Claeys "Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry." <i>Catalysts</i> 11, 5. (2021): 636. http://hdl.handle.net/11427/35226en_ZA
dc.identifier.citationMaphutha, M., de Oliveira, D., Nyathi, T.M., Fadlalla, M.I., Henkel, R., Fischer, N. & Claeys, M. 2021. Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry. <i>Catalysts.</i> 11(5):636. http://hdl.handle.net/11427/35226en_ZA
dc.identifier.ris TY - Journal Article AU - Maphutha, Malebelo AU - de Oliveira, Dominic AU - Nyathi, Thulani M AU - Fadlalla, Mohamed I AU - Henkel, Robert AU - Fischer, Nico AU - Claeys, Michael AB - The presented study investigated the effects of temperature (350–650 ◦C) and gas environment (pure Ar versus a H2O/H2 partial pressure ratio (PH2O/PH2) of 5) on the extent of sintering and oxidation of Al2O3 -supported Ni0 nanoparticles (≈4 nm). We note that a PH2O/PH2 of 5 corresponds to a simulated CO conversion of 94% during methanation. Sintering and oxidation were studied using in situ magnetometry, while ex situ TEM analyses confirmed the particle sizes before and after the magnetometry-based experiments. It was found that increasing the temperature from 350 to 650 ◦C in Ar at atmospheric pressure causes a negligible change to the average size and degree of reduction (DOR) of the starting Ni0 nanoparticles. However, studying the same temperature window under hydrothermal conditions at 10 bar causes significant particle growth (≈9 nm) and the development of a bimodal distribution. Furthermore, the presence of steam decreases the DOR of Ni0 from 86.2% after initial activation to 22.2% due to oxidation. In summary, this study reports on the expected sintering and oxidation of Ni-based catalysts under high CO conversion conditions at elevated temperatures during methanation. Importantly, we were able to demonstrate how magnetometry-based analyses can provide similar size information (and changes thereof) as those observed with TEM but with the added advantage that this information can be obtained in situ. DA - 2021-05-16 DB - OpenUCT DP - University of Cape Town IS - 5 J1 - Catalysts LK - https://open.uct.ac.za PY - 2021 T1 - Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry TI - Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry UR - http://hdl.handle.net/11427/35226 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/35226
dc.identifier.vancouvercitationMaphutha M, de Oliveira D, Nyathi TM, Fadlalla MI, Henkel R, Fischer N, et al. Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry. Catalysts. 2021;11(5):636. http://hdl.handle.net/11427/35226.en_ZA
dc.language.isoenen_US
dc.publisher.departmentDepartment of Chemical Engineering
dc.publisher.facultyFaculty of Engineering and the Built Environmenten_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en_US
dc.sourceCatalystsen_US
dc.source.journalissue5en_US
dc.source.journalvolume11en_US
dc.source.pagination636en_US
dc.source.urihttps://www.mdpi.com/journal/catalysts
dc.titleHydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometryen_US
dc.typeJournal Articleen_US
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