Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification
Main Author: | |
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Publication Date: | 2018 |
Other Authors: | , |
Format: | Article |
Language: | eng |
Source: | Repositório Institucional da UFLA |
Download full: | http://repositorio.ufla.br/jspui/handle/1/34678 |
Summary: | The innumerous advantages of heterogeneous catalysts employed in biodiesel production have stimulated the search for a solid catalyst capable of replacing the industrially used homogeneous catalysts. This paper investigates the effect of the sol-gel method in the catalytic activity and stability of Li-MgAl mixed oxides prepared by the “in situ” lithium addition to a MgAl hydrotalcite. The analyses based on N2 physisorption, thermogravimetric analysis, X-ray diffractometry, scanning electron microscopy and temperature-programmed desorption of CO2 were carried out to elucidate the properties of the catalysts. Considerable differences in the physico-chemical properties of the catalysts were observed with the Li addition. Li reduced the surface area and increased the crystallite size of the oxides. Furthermore, Li-MgAl mixed oxides prepared by the calcination of the sol-gel MgAl hydrotalcites presented substantial morphological differences when compared to the same oxides obtained by heat treatment of hydrotalcites synthesized via the conventional co-precipitation route. Furthermore, Li increased the number and strength of the base sites which resulted in the increase of the oxide reactivities towards the transesterification reaction between methyl acetate and ethanol. The activity was dependent on the Li loading on the catalysts. The catalyst containing only 5 wt.% Li turned out to be highly active (( 85% conversion at 50°C, ethanol/methyl acetate molar ratio = 6/1, 4 wt.% of catalyst and 30 min of reaction). Stability tests showed that the Li-MgAl catalysts lose activity after 3 reuse cycles. |
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Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterificationHydrotalciteSol-gel methodTransesterificationLithiumMixed oxideHeterogeneous catalysisThe innumerous advantages of heterogeneous catalysts employed in biodiesel production have stimulated the search for a solid catalyst capable of replacing the industrially used homogeneous catalysts. This paper investigates the effect of the sol-gel method in the catalytic activity and stability of Li-MgAl mixed oxides prepared by the “in situ” lithium addition to a MgAl hydrotalcite. The analyses based on N2 physisorption, thermogravimetric analysis, X-ray diffractometry, scanning electron microscopy and temperature-programmed desorption of CO2 were carried out to elucidate the properties of the catalysts. Considerable differences in the physico-chemical properties of the catalysts were observed with the Li addition. Li reduced the surface area and increased the crystallite size of the oxides. Furthermore, Li-MgAl mixed oxides prepared by the calcination of the sol-gel MgAl hydrotalcites presented substantial morphological differences when compared to the same oxides obtained by heat treatment of hydrotalcites synthesized via the conventional co-precipitation route. Furthermore, Li increased the number and strength of the base sites which resulted in the increase of the oxide reactivities towards the transesterification reaction between methyl acetate and ethanol. The activity was dependent on the Li loading on the catalysts. The catalyst containing only 5 wt.% Li turned out to be highly active (( 85% conversion at 50°C, ethanol/methyl acetate molar ratio = 6/1, 4 wt.% of catalyst and 30 min of reaction). Stability tests showed that the Li-MgAl catalysts lose activity after 3 reuse cycles.Brazilian Society of Chemical Engineering2019-06-07T10:31:17Z2019-06-07T10:31:17Z2018info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfLIMA-CORRÊA, R. A. B.; CASTRO, C. S.; ASSAF, J. M. Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification. Brazilian Journal of Chemical Engineering, São Paulo, v. 35, n. 1, p. 189 - 195, Jan./Mar. 2018.http://repositorio.ufla.br/jspui/handle/1/34678Brazilian Journal of Chemical Engineeringreponame:Repositório Institucional da UFLAinstname:Universidade Federal de Lavras (UFLA)instacron:UFLAAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/info:eu-repo/semantics/openAccessLima-Corrêa, Renata A. B.Castro, Cínthia S.Assaf, José M.eng2019-06-07T10:31:18Zoai:localhost:1/34678Repositório InstitucionalPUBhttp://repositorio.ufla.br/oai/requestnivaldo@ufla.br || repositorio.biblioteca@ufla.bropendoar:2019-06-07T10:31:18Repositório Institucional da UFLA - Universidade Federal de Lavras (UFLA)false |
dc.title.none.fl_str_mv |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
title |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
spellingShingle |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification Lima-Corrêa, Renata A. B. Hydrotalcite Sol-gel method Transesterification Lithium Mixed oxide Heterogeneous catalysis |
title_short |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
title_full |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
title_fullStr |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
title_full_unstemmed |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
title_sort |
Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification |
author |
Lima-Corrêa, Renata A. B. |
author_facet |
Lima-Corrêa, Renata A. B. Castro, Cínthia S. Assaf, José M. |
author_role |
author |
author2 |
Castro, Cínthia S. Assaf, José M. |
author2_role |
author author |
dc.contributor.author.fl_str_mv |
Lima-Corrêa, Renata A. B. Castro, Cínthia S. Assaf, José M. |
dc.subject.por.fl_str_mv |
Hydrotalcite Sol-gel method Transesterification Lithium Mixed oxide Heterogeneous catalysis |
topic |
Hydrotalcite Sol-gel method Transesterification Lithium Mixed oxide Heterogeneous catalysis |
description |
The innumerous advantages of heterogeneous catalysts employed in biodiesel production have stimulated the search for a solid catalyst capable of replacing the industrially used homogeneous catalysts. This paper investigates the effect of the sol-gel method in the catalytic activity and stability of Li-MgAl mixed oxides prepared by the “in situ” lithium addition to a MgAl hydrotalcite. The analyses based on N2 physisorption, thermogravimetric analysis, X-ray diffractometry, scanning electron microscopy and temperature-programmed desorption of CO2 were carried out to elucidate the properties of the catalysts. Considerable differences in the physico-chemical properties of the catalysts were observed with the Li addition. Li reduced the surface area and increased the crystallite size of the oxides. Furthermore, Li-MgAl mixed oxides prepared by the calcination of the sol-gel MgAl hydrotalcites presented substantial morphological differences when compared to the same oxides obtained by heat treatment of hydrotalcites synthesized via the conventional co-precipitation route. Furthermore, Li increased the number and strength of the base sites which resulted in the increase of the oxide reactivities towards the transesterification reaction between methyl acetate and ethanol. The activity was dependent on the Li loading on the catalysts. The catalyst containing only 5 wt.% Li turned out to be highly active (( 85% conversion at 50°C, ethanol/methyl acetate molar ratio = 6/1, 4 wt.% of catalyst and 30 min of reaction). Stability tests showed that the Li-MgAl catalysts lose activity after 3 reuse cycles. |
publishDate |
2018 |
dc.date.none.fl_str_mv |
2018 2019-06-07T10:31:17Z 2019-06-07T10:31:17Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
LIMA-CORRÊA, R. A. B.; CASTRO, C. S.; ASSAF, J. M. Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification. Brazilian Journal of Chemical Engineering, São Paulo, v. 35, n. 1, p. 189 - 195, Jan./Mar. 2018. http://repositorio.ufla.br/jspui/handle/1/34678 |
identifier_str_mv |
LIMA-CORRÊA, R. A. B.; CASTRO, C. S.; ASSAF, J. M. Lithium containing MgAl mixed oxides obtained from sol-gel hydrotalcite for transesterification. Brazilian Journal of Chemical Engineering, São Paulo, v. 35, n. 1, p. 189 - 195, Jan./Mar. 2018. |
url |
http://repositorio.ufla.br/jspui/handle/1/34678 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Brazilian Society of Chemical Engineering |
publisher.none.fl_str_mv |
Brazilian Society of Chemical Engineering |
dc.source.none.fl_str_mv |
Brazilian Journal of Chemical Engineering reponame:Repositório Institucional da UFLA instname:Universidade Federal de Lavras (UFLA) instacron:UFLA |
instname_str |
Universidade Federal de Lavras (UFLA) |
instacron_str |
UFLA |
institution |
UFLA |
reponame_str |
Repositório Institucional da UFLA |
collection |
Repositório Institucional da UFLA |
repository.name.fl_str_mv |
Repositório Institucional da UFLA - Universidade Federal de Lavras (UFLA) |
repository.mail.fl_str_mv |
nivaldo@ufla.br || repositorio.biblioteca@ufla.br |
_version_ |
1784550067594592256 |