The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5
dc.contributor.author | Weber, R W | |
dc.contributor.author | Möller, K P | |
dc.contributor.author | Unger, M | |
dc.contributor.author | O'Connor, C | |
dc.date.accessioned | 2016-08-05T10:37:15Z | |
dc.date.available | 2016-08-05T10:37:15Z | |
dc.date.issued | 1998 | |
dc.date.updated | 2016-08-01T08:37:56Z | |
dc.description.abstract | The external acidity of ZSM-5 was modified by chemical vapour deposition (CVD) and chemical liquid deposition (CLD) of tetraethoxysilane [Si(OC2 H5 ) 4 ] using a static vacuum system, a vapour phase flow system and liquid phase deposition. Temperature programmed desorption (TPD) techniques were used to characterise the acidity changes arising from these modifications. Pyridine was used as a probe for the total acidity and 4-methyl quinoline (MQ) was used to probe the external acidity. The adsorption capacities of the samples were measured using n-hexane, p-xylene, o-xylene and 1,2,4-trimethyl benzene. The extent of Si(OC2 H5 ) 4 deposition was strongly dependent on temperature in both vapour phase flow and static vacuum systems. Continuous Si(OC2 H5 ) 4 deposition was observed in the presence of H2 O at relatively high temperatures when decomposition products were removed from the sample. It is proposed that physisorbed species need to be removed by evacuation or calcination to re-expose active sites, thereby enabling complete inertisation of the external surface acidity to occur, and that a more uniform covering can be obtained when a gradual deposition process is used. Such a process may be achieved by the use of diluents or by preventing overexposure of Si(OC2 H5 ) 4 to the sample under conditions where continuous deposition may occur. It was shown that it is possible to reduce the relative external surface acidity by 97% without significant changes in acidity as measured by Py-TPD or adsorption capacity. | en_ZA |
dc.identifier | http://dx.doi.org/10.1016/S1387-1811(98)00061-4 | |
dc.identifier.apacitation | Weber, R. W., Möller, K. P., Unger, M., & O'Connor, C. (1998). The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5. <i>Microporous and Mesoporous Materials</i>, http://hdl.handle.net/11427/21133 | en_ZA |
dc.identifier.chicagocitation | Weber, R W, K P Möller, M Unger, and C O'Connor "The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5." <i>Microporous and Mesoporous Materials</i> (1998) http://hdl.handle.net/11427/21133 | en_ZA |
dc.identifier.citation | Weber, R. W., Möller, K. P., Unger, M., & O'Connor, C. T. (1998). The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5. Microporous and mesoporous materials, 23(3), 179-187. | en_ZA |
dc.identifier.issn | 1387-1811 | en_ZA |
dc.identifier.ris | TY - Journal Article AU - Weber, R W AU - Möller, K P AU - Unger, M AU - O'Connor, C AB - The external acidity of ZSM-5 was modified by chemical vapour deposition (CVD) and chemical liquid deposition (CLD) of tetraethoxysilane [Si(OC2 H5 ) 4 ] using a static vacuum system, a vapour phase flow system and liquid phase deposition. Temperature programmed desorption (TPD) techniques were used to characterise the acidity changes arising from these modifications. Pyridine was used as a probe for the total acidity and 4-methyl quinoline (MQ) was used to probe the external acidity. The adsorption capacities of the samples were measured using n-hexane, p-xylene, o-xylene and 1,2,4-trimethyl benzene. The extent of Si(OC2 H5 ) 4 deposition was strongly dependent on temperature in both vapour phase flow and static vacuum systems. Continuous Si(OC2 H5 ) 4 deposition was observed in the presence of H2 O at relatively high temperatures when decomposition products were removed from the sample. It is proposed that physisorbed species need to be removed by evacuation or calcination to re-expose active sites, thereby enabling complete inertisation of the external surface acidity to occur, and that a more uniform covering can be obtained when a gradual deposition process is used. Such a process may be achieved by the use of diluents or by preventing overexposure of Si(OC2 H5 ) 4 to the sample under conditions where continuous deposition may occur. It was shown that it is possible to reduce the relative external surface acidity by 97% without significant changes in acidity as measured by Py-TPD or adsorption capacity. DA - 1998 DB - OpenUCT DP - University of Cape Town J1 - Microporous and Mesoporous Materials LK - https://open.uct.ac.za PB - University of Cape Town PY - 1998 SM - 1387-1811 T1 - The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5 TI - The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5 UR - http://hdl.handle.net/11427/21133 ER - | en_ZA |
dc.identifier.uri | http://hdl.handle.net/11427/21133 | |
dc.identifier.vancouvercitation | Weber RW, Möller KP, Unger M, O'Connor C. The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5. Microporous and Mesoporous Materials. 1998; http://hdl.handle.net/11427/21133. | en_ZA |
dc.language | eng | en_ZA |
dc.publisher | Elsevier | en_ZA |
dc.publisher.institution | University of Cape Town | |
dc.rights | Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) | * |
dc.rights.uri | https://creativecommons.org/licenses/by-nc-nd/4.0/ | en_ZA |
dc.source | Microporous and Mesoporous Materials | en_ZA |
dc.source.uri | http://www.sciencedirect.com/science/journal/13871811 | |
dc.subject.other | ZSM-5 | |
dc.subject.other | CVD | |
dc.subject.other | TPD | |
dc.subject.other | Adsorption | |
dc.subject.other | External surface | |
dc.title | The chemical vapour and liquid deposition of tetraethoxysilane on the external surface of ZSM-5 | en_ZA |
dc.type | Journal Article | en_ZA |
uct.type.filetype | Text | |
uct.type.filetype | Image | |
uct.type.publication | Research | en_ZA |
uct.type.resource | Article | en_ZA |