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A variable-temperature diffuse reflectance infrared Fourier transform spectroscopy study of the binding of water and pyridine to the surface of acid-activated metakaolin

2005Journal article Open access
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dc.contributor.authorBelver, Carolina
dc.contributor.authorBreen, Christopher
dc.contributor.authorClegg, Francis
dc.contributor.authorFernandes, César E.
dc.contributor.authorVicente, Miguel A.
dc.date.accessioned2023-02-02T09:21:50Z
dc.date.available2023-02-02T09:21:50Z
dc.date.issued2005
dc.description.abstractFour metakaolins were prepared by heating a Spanish kaolin at 600, 700, 800, and 900 °C for 10 h. Following preliminary optimization, these metakaolins were acid activated in 6 M hydrochloric acid at 90 °C for 6 h; the samples calcined at 600, 700, and 800 °C produced the highest surface area solids and were selected for further study. Variable-temperature diffuse reflectance infrared Fourier transform spectroscopy analysis of the resulting acid-activated metakaolins (AAMKs) identified a wide range of hydrogen bond strengths in adsorbed water at room temperature. Above 300 °C it was possible to fit the broad hydroxyl stretching band to seven contributing components at 3730, 3700, 3655, 3615, 3583, 3424, and 3325 cm-1. As the sample temperature was increased, the 3730 cm-1 band increased in intensity as the water hydrogen bonded to AlOHAl was thermally desorbed. The other six bands decreased in intensity. The spectra of adsorbed pyridine indicated the presence of both Bro¨nsted and Lewis acid sites on the surface of the air-dried AAMKs. Preheating the AAMK at 200 °C prior to pyridine sorption reduced the number of Bro¨nsted acid sites and increased the number of thermally stable Lewis acid sites. A reduction in the amount of adsorbed pyridine after pretreating the AAMK at 400 °C was tentatively attributed to a reduction in surface area. This was reflected in fewer thermally stable Lewis acid sites in the AAMK pretreated at 400 °C compared to the number present in the sample pretreated at 200 °C.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationBelver, C., Breen, C., Clegg, F., Fernandes, C. E., & Vicente, M. A. (2005). A variable-temperature diffuse reflectance infrared Fourier transform spectroscopy study of the binding of water and pyridine to the surface of acid-activated metakaolin. Langmuir, 21(6), 2129-2136.pt_PT
dc.identifier.doi10.1021/la048323mpt_PT
dc.identifier.urihttp://hdl.handle.net/10400.13/4987
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherAmerican Chemical Societypt_PT
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/pt_PT
dc.subjectAdsorption propertiespt_PT
dc.subjectHydroxylspt_PT
dc.subjectPretreatmentpt_PT
dc.subjectPyridinespt_PT
dc.subjectSilicapt_PT
dc.subjectMetakaolinspt_PT
dc.subject.pt_PT
dc.subjectFaculdade de Ciências Exatas e da Engenhariapt_PT
dc.titleA variable-temperature diffuse reflectance infrared Fourier transform spectroscopy study of the binding of water and pyridine to the surface of acid-activated metakaolinpt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage2136pt_PT
oaire.citation.issue6pt_PT
oaire.citation.startPage2129pt_PT
oaire.citation.titleLangmuirpt_PT
oaire.citation.volume21pt_PT
person.familyNameFernandes
person.givenNameCesar
person.identifier.orcid0000-0001-9289-9962
person.identifier.scopus-author-id14064572200
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT
relation.isAuthorOfPublication482857a3-4e6d-4453-bfc1-afb17ff8ce2a
relation.isAuthorOfPublication.latestForDiscovery482857a3-4e6d-4453-bfc1-afb17ff8ce2a

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