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DC Field | Value | Language |
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dc.citation.endPage | 68 | - |
dc.citation.startPage | 58 | - |
dc.citation.title | APPLIED CATALYSIS A-GENERAL | - |
dc.citation.volume | 500 | - |
dc.contributor.author | Lee, Jaekyoung | - |
dc.contributor.author | Jeon, Himchan | - |
dc.contributor.author | Oh, Dong Gun | - |
dc.contributor.author | Szanyi, Janos | - |
dc.contributor.author | Kwak, Ja Hun | - |
dc.date.accessioned | 2023-12-22T01:07:55Z | - |
dc.date.available | 2023-12-22T01:07:55Z | - |
dc.date.created | 2015-08-03 | - |
dc.date.issued | 2015-07 | - |
dc.description.abstract | The phase transformations of platelet- and rod-shaped gamma-Al2O3 were investigated and compared to that of a commercial sample by XRD, BET surface area measurements, transmission electron microscopy (TEM), solid state Al-27-NMR, and ethanol temperature programmed desorption (TPD) after sequential annealing in air up to 1100 degrees C. After annealing at 1100 degrees C, commercial gamma-Al2O3 mostly transformed into alpha-Al2O3 with drastic surface area reduction (from 200 m(2)/g to 25 m(2)/g). Interestingly, platelet- and rod-shaped gamma-Al2O3 which showed exactly the same XRD patterns transformed into different phases upon the high temperature calcinations. Platelet-shaped gamma-Al2O3 transformed into theta-phase while the rod-shaped gamma-Al2O3 transformed into the delta-phase and not to the alpha-polymorph. Both platelet- and rod-shaped aluminas retained significantly higher surface area (similar to 60 m(2)/g) than the commercial one after the same treatment at 1100 degrees C. These results suggest that the phase transformation in gamma-Al2O3 is strongly affected by not only the crystal structure of the starting material, but its morphology as well. Ethanol TPD from platelet- and rod-shaped alumina after 1100 degrees C annealing, showed significantly different desorption profiles which suggest different surface characteristics even though they had almost the same surface areas. These different phase transformations were also supported by solid state Al-27-NMR. After 1100 degrees C annealing commercial alumina showed the presence of mostly octahedral Al3+ ions, but the other two samples displayed even higher number of tetrahedral Al3+ ions than the initial gamma-Al2O3. Morphological changes were also confirmed by TEM. All these results consistently suggest the morphology-dependent phase transformations of gamma-Al2O3 and the improved thermal stability of platelet- and rod-shaped gamma-Al2O3 in comparison to a commercial gamma-Al2O3. (C) 2015 Elsevier B.V. All rights reserved. | - |
dc.identifier.bibliographicCitation | APPLIED CATALYSIS A-GENERAL, v.500, pp.58 - 68 | - |
dc.identifier.doi | 10.1016/j.apcata.2015.03.040 | - |
dc.identifier.issn | 0926-860X | - |
dc.identifier.scopusid | 2-s2.0-84968764298 | - |
dc.identifier.uri | https://scholarworks.unist.ac.kr/handle/201301/13384 | - |
dc.identifier.url | http://www.sciencedirect.com/science/article/pii/S0926860X15002264 | - |
dc.identifier.wosid | 000357141700008 | - |
dc.language | 영어 | - |
dc.publisher | ELSEVIER SCIENCE BV | - |
dc.title | Morphology-dependent phase transformation of γ-Al2O3 | - |
dc.type | Article | - |
dc.description.isOpenAccess | FALSE | - |
dc.relation.journalWebOfScienceCategory | Chemistry, Physical; Environmental Sciences | - |
dc.relation.journalResearchArea | Chemistry; Environmental Sciences & Ecology | - |
dc.description.journalRegisteredClass | scie | - |
dc.description.journalRegisteredClass | scopus | - |
dc.subject.keywordAuthor | gamma-Al2O3 | - |
dc.subject.keywordAuthor | Phase transformation | - |
dc.subject.keywordAuthor | Morphology | - |
dc.subject.keywordAuthor | TEM | - |
dc.subject.keywordAuthor | Ethanol-TPD | - |
dc.subject.keywordPlus | GAMMA-ALUMINA | - |
dc.subject.keywordPlus | SURFACE-AREA | - |
dc.subject.keywordPlus | HYDROTHERMAL SYNTHESIS | - |
dc.subject.keywordPlus | TRANSITIONAL ALUMINAS | - |
dc.subject.keywordPlus | ETHANOL DEHYDRATION | - |
dc.subject.keywordPlus | THERMAL-STABILITY | - |
dc.subject.keywordPlus | PARTICLE-SIZE | - |
dc.subject.keywordPlus | BOEHMITE | - |
dc.subject.keywordPlus | NANOPARTICLES | - |
dc.subject.keywordPlus | MECHANISM | - |
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