Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH) (CH3COO)2 crystals
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| Format: | Artículo científico |
| Language: | en |
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Academia Brasileira de Ciências
2000
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| _version_ | 1876446281813983232 |
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| author | Pedro K. Kiyohara |
| author_facet | Pedro K. Kiyohara |
| contents | Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH) (CH3COO)2 crystals Pedro K. Kiyohara Helena Santos Souza Antonio C. Coelho Vieira Pérsio Santos de Souza Multidisciplinaria (Ciencias Naturales y Exactas) boehmite active aluminas transition aluminas aluminum hydroxides aluminium hydroxiacetate Crystalline aluminium hydroxiacetate was prepared by reaction between aluminium powder (ALCOA123) and aqueous solution of acetic acid at 96◦C±1◦C. The white powder ofAl(OH)(CH3COO)2 is constituted by agglomerates of crystalline plates, having size about 10µm.The crystals were fired from 200◦C to 1550◦C, in oxidizing atmosphere and the products characterizedby X-ray diffraction, scanning electron microscopy and surface area measurements byBET-nitrogen method. Transition aluminas are formed from heating at the following temperatures:gamma (300◦C); delta (750◦C); alpha (1050◦C). The aluminas maintain the original morphologyof the Al(OH)Ac2 crystal agglomerates, up to 1050◦C, when sintering and coalescence of thealpha-alumina crystals start and proceed up to 1550◦C. High surface area aluminas are formed inthe temperature range of 700◦C to 1100◦C; the maximum value of 198m2/g is obtained at 900◦C,with delta-alumina structure. The formation sequence of transition aluminas is similar to the sequencefrom well ordered boehmite, but with differences in the transition temperatures and in thedevelopment of high surface areas. It is suggested that the causes for these diversities between thetwo sequences from Al(OH) Ac2 and boehmite are due to the different particle sizes, shapes andtextures of the gamma-Al2O3 which acts as precursor for the sequence gamma- to alpha-Al2O3. 2000 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32772403 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.72 |
| format | Artículo científico |
| id | redalyc_32772403 |
| institution | Redalyc |
| language | en |
| publishDate | 2000 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH) (CH3COO)2 crystals Pedro K. Kiyohara Multidisciplinaria (Ciencias Naturales y Exactas) boehmite active aluminas transition aluminas aluminum hydroxides aluminium hydroxiacetate Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH) (CH3COO)2 crystals Pedro K. Kiyohara Helena Santos Souza Antonio C. Coelho Vieira Pérsio Santos de Souza Multidisciplinaria (Ciencias Naturales y Exactas) boehmite active aluminas transition aluminas aluminum hydroxides aluminium hydroxiacetate Crystalline aluminium hydroxiacetate was prepared by reaction between aluminium powder (ALCOA123) and aqueous solution of acetic acid at 96◦C±1◦C. The white powder ofAl(OH)(CH3COO)2 is constituted by agglomerates of crystalline plates, having size about 10µm.The crystals were fired from 200◦C to 1550◦C, in oxidizing atmosphere and the products characterizedby X-ray diffraction, scanning electron microscopy and surface area measurements byBET-nitrogen method. Transition aluminas are formed from heating at the following temperatures:gamma (300◦C); delta (750◦C); alpha (1050◦C). The aluminas maintain the original morphologyof the Al(OH)Ac2 crystal agglomerates, up to 1050◦C, when sintering and coalescence of thealpha-alumina crystals start and proceed up to 1550◦C. High surface area aluminas are formed inthe temperature range of 700◦C to 1100◦C; the maximum value of 198m2/g is obtained at 900◦C,with delta-alumina structure. The formation sequence of transition aluminas is similar to the sequencefrom well ordered boehmite, but with differences in the transition temperatures and in thedevelopment of high surface areas. It is suggested that the causes for these diversities between thetwo sequences from Al(OH) Ac2 and boehmite are due to the different particle sizes, shapes andtextures of the gamma-Al2O3 which acts as precursor for the sequence gamma- to alpha-Al2O3. 2000 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32772403 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.72 |
| title | Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH) (CH3COO)2 crystals |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) boehmite active aluminas transition aluminas aluminum hydroxides aluminium hydroxiacetate |
| url | https://www.redalyc.org/articulo.oa?id=32772403 |