Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production
<abstract language="eng">The catalytic dehydrogenation of ethylbenzene in presence of steam is the main commercial route to produce styrene. The industrial catalysts are potassium- and chromia-doped hematite which show low surface areas leading to bad performance and short life. In o...
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| Format: | Article |
| Language: | English |
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Sociedade Brasileira de Química
1997-10-01
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| Series: | Química Nova |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40421997000500004 |
| _version_ | 1818217093440471040 |
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| author | Mário Nilo Mendes Barbosa Marly Fernandes Araújo de Carvalho Maria do Carmo Rangel |
| author_facet | Mário Nilo Mendes Barbosa Marly Fernandes Araújo de Carvalho Maria do Carmo Rangel |
| author_sort | Mário Nilo Mendes Barbosa |
| collection | DOAJ |
| description | <abstract language="eng">The catalytic dehydrogenation of ethylbenzene in presence of steam is the main commercial route to produce styrene. The industrial catalysts are potassium- and chromia-doped hematite which show low surface areas leading to bad performance and short life. In order to develop catalysts with high areas, the effect of beryllium on the textural properties and on the catalytic performance of this iron oxide was studied. The influence of the amount of the dopant, the starting material and the calcination temperature were also studied. In sample preparations, iron and beryllium salts (nitrate or sulfate) were hydrolyzed with ammonia and then calcinated. The experiments followed a factorial design with two variables in two levels (Fe/Be= 3 and 7; calcination temperature= 500 and 700ºC). Solids without any dopant were also prepared. Samples were characterized by elemental analysis, infrared spectroscopy, surface area and porosity measurements, X-ray diffraction, DSC and TG. The catalysts were tested in a microreactor at 524ºC and 1 atm, by using a mole ratio of steam/ ethylbenzene=10. The selectivity was measured by monitoring styrene, benzene and toluene formation. It was found that the effect of beryllium on the characteristics of hematite and on its catalytic performance depends on the starting material and on the amount of dopant. Surface areas increased due to the dopant as well as the nature of the precursor; samples produced by beryllium sulfate showed higher areas. Beryllium-doped solids showed a higher catalytic activity when compared to pure hematite, but no significant influence of the anion of starting material was noted. It can be concluded that beryllium acts as both textural and structural promoter. Samples with Fe/Be= 3, heated at 500ºC, lead to the highest conversion and were the most selective. However, catalysts prepared from beryllium sulfate are the most promising to ethylbenzene dehydrogenation due to their high surface area which could lead to a longer life. |
| first_indexed | 2024-12-12T07:02:23Z |
| format | Article |
| id | doaj.art-7870bbe460cb401f9265d457f49902a2 |
| institution | Directory Open Access Journal |
| issn | 0100-4042 1678-7064 |
| language | English |
| last_indexed | 2024-12-12T07:02:23Z |
| publishDate | 1997-10-01 |
| publisher | Sociedade Brasileira de Química |
| record_format | Article |
| series | Química Nova |
| spelling | doaj.art-7870bbe460cb401f9265d457f49902a22022-12-22T00:33:50ZengSociedade Brasileira de QuímicaQuímica Nova0100-40421678-70641997-10-0120546346810.1590/S0100-40421997000500004Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene productionMário Nilo Mendes BarbosaMarly Fernandes Araújo de CarvalhoMaria do Carmo Rangel<abstract language="eng">The catalytic dehydrogenation of ethylbenzene in presence of steam is the main commercial route to produce styrene. The industrial catalysts are potassium- and chromia-doped hematite which show low surface areas leading to bad performance and short life. In order to develop catalysts with high areas, the effect of beryllium on the textural properties and on the catalytic performance of this iron oxide was studied. The influence of the amount of the dopant, the starting material and the calcination temperature were also studied. In sample preparations, iron and beryllium salts (nitrate or sulfate) were hydrolyzed with ammonia and then calcinated. The experiments followed a factorial design with two variables in two levels (Fe/Be= 3 and 7; calcination temperature= 500 and 700ºC). Solids without any dopant were also prepared. Samples were characterized by elemental analysis, infrared spectroscopy, surface area and porosity measurements, X-ray diffraction, DSC and TG. The catalysts were tested in a microreactor at 524ºC and 1 atm, by using a mole ratio of steam/ ethylbenzene=10. The selectivity was measured by monitoring styrene, benzene and toluene formation. It was found that the effect of beryllium on the characteristics of hematite and on its catalytic performance depends on the starting material and on the amount of dopant. Surface areas increased due to the dopant as well as the nature of the precursor; samples produced by beryllium sulfate showed higher areas. Beryllium-doped solids showed a higher catalytic activity when compared to pure hematite, but no significant influence of the anion of starting material was noted. It can be concluded that beryllium acts as both textural and structural promoter. Samples with Fe/Be= 3, heated at 500ºC, lead to the highest conversion and were the most selective. However, catalysts prepared from beryllium sulfate are the most promising to ethylbenzene dehydrogenation due to their high surface area which could lead to a longer life.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40421997000500004ethylbenzene dehydrogenationstyreneiron oxides |
| spellingShingle | Mário Nilo Mendes Barbosa Marly Fernandes Araújo de Carvalho Maria do Carmo Rangel Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production Química Nova ethylbenzene dehydrogenation styrene iron oxides |
| title | Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production |
| title_full | Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production |
| title_fullStr | Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production |
| title_full_unstemmed | Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production |
| title_short | Ação promotora do berílio em catalisadores da síntese do estireno Promotor action of beryllium in catalysts for styrene production |
| title_sort | acao promotora do berilio em catalisadores da sintese do estireno promotor action of beryllium in catalysts for styrene production |
| topic | ethylbenzene dehydrogenation styrene iron oxides |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40421997000500004 |
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