The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography

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dc.contributor.authorDuncan, Warwicken_ZA
dc.date.accessioned2014-10-24T07:29:54Z
dc.date.available2014-10-24T07:29:54Z
dc.date.issued2001en_ZA
dc.descriptionBibliography: p. 97-102.en_ZA
dc.description.abstractZeolites are important solid acid catalysts largely because of their microporous nature giving them strong shape selective properties. This shape selectivity may be improved by depositing an inert (e. g. silaceous) layer on the surface of the catalyst crystals, which inertises non-shape selective surface acid sites and increases diffusional transport resistances. This thesis presents an investigation, using the zero length column (ZLC) method, into changes in the diffusional properties of cyclohexane in ZSM-5 that has had tetraethoxysilane deposited on the surface in the liquid phase. Theoretical analyses of the ZLC technique and its use in a detailed study of cyclohexane in unmodified ZSM-5 were performed in order to prove the reliability of the technique and measure baseline behaviour of the selected system. The ZLC method is a chromatographic technique for the measurement of diffusion coefficients in porous sorbents. Originally developed for gaseous hydrocarbon / zeolite powder systems, it has been experimentally extended to the measurement of liquid sorbate systems, macroporous zeolite pellets and resins and the measurement of self-diffusion through tracer exchange. The technique is robust against the intrusion of external heat and mass transfer effects by the use of relatively high flow rates and small catalyst samples, Analysis of the desorption curves is simple: the slope of the linear (on semilogarthmic axes) long time region gives the diffusional time constant. This so-called 'long time' analysis gives an accurate result for the diilusional time constant.en_ZA
dc.identifier.apacitationDuncan, W. (2001). <i>The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering. Retrieved from http://hdl.handle.net/11427/8743en_ZA
dc.identifier.chicagocitationDuncan, Warwick. <i>"The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 2001. http://hdl.handle.net/11427/8743en_ZA
dc.identifier.citationDuncan, W. 2001. The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Duncan, Warwick AB - Zeolites are important solid acid catalysts largely because of their microporous nature giving them strong shape selective properties. This shape selectivity may be improved by depositing an inert (e. g. silaceous) layer on the surface of the catalyst crystals, which inertises non-shape selective surface acid sites and increases diffusional transport resistances. This thesis presents an investigation, using the zero length column (ZLC) method, into changes in the diffusional properties of cyclohexane in ZSM-5 that has had tetraethoxysilane deposited on the surface in the liquid phase. Theoretical analyses of the ZLC technique and its use in a detailed study of cyclohexane in unmodified ZSM-5 were performed in order to prove the reliability of the technique and measure baseline behaviour of the selected system. The ZLC method is a chromatographic technique for the measurement of diffusion coefficients in porous sorbents. Originally developed for gaseous hydrocarbon / zeolite powder systems, it has been experimentally extended to the measurement of liquid sorbate systems, macroporous zeolite pellets and resins and the measurement of self-diffusion through tracer exchange. The technique is robust against the intrusion of external heat and mass transfer effects by the use of relatively high flow rates and small catalyst samples, Analysis of the desorption curves is simple: the slope of the linear (on semilogarthmic axes) long time region gives the diffusional time constant. This so-called 'long time' analysis gives an accurate result for the diilusional time constant. DA - 2001 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2001 T1 - The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography TI - The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography UR - http://hdl.handle.net/11427/8743 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/8743
dc.identifier.vancouvercitationDuncan W. The measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatography. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Chemical Engineering, 2001 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/8743en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Chemical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemical Engineeringen_ZA
dc.titleThe measurement and modelling of the intracrystalline diffusion of cyclohexane in ZSM-5 using zero length column chromatographyen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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