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CaAl-layered double hydroxides as active catalysts for the transesterification of glycerol to glycerol carbonate
AbstractSeveral hydrocalumite-type materials (CaAl-LDHs) were prepared by precipitation using nitrate or chloride salts with and without ultrasound, and aged hydrothermally in autoclave or by refluxing with and without microwaves. These samples were tested as catalysts for the transesterification of glycerol with dimethyl carbonate to glycerol carbonate. After 3h of reaction, all catalysts showed high glycerol conversion (70–84%) and moderate selectivity values to glycerol carbonate (52–65%) accompanied by the formation of low amounts of glycidol (7–15%). These results are very interesting taking into account the low specific surface area of these catalysts (7–25m2/g). No significant catalytic differences were observed between the catalysts. This can be due to the similar surface and basic characteristics observed for all of them. By increasing the reaction time, an increase of conversion was observed arriving practically to total conversion after 24h of reaction, with selectivity to glycerol carbonate in the range 65–75%. Several catalytic reuses favoured the decarboxylation of glycerol carbonate resulting in the formation of higher amounts of glycidol (30%) but still maintaining high selectivity values to glycerol carbonate (70%).
Graphical abstract
HighlightsSynthesized CaAl-LDHs catalysts had similar surface and basic properties.CaAl-LDHs catalysts were highly active for the conversion of glycerol.CaAl-LDHs catalysts led to significant selectivity values to glycerol carbonate.Catalytic reuse favoured decarbonylation of glycerol carbonate to glycidol.
CaAl-layered double hydroxides as active catalysts for the transesterification of glycerol to glycerol carbonate
AbstractSeveral hydrocalumite-type materials (CaAl-LDHs) were prepared by precipitation using nitrate or chloride salts with and without ultrasound, and aged hydrothermally in autoclave or by refluxing with and without microwaves. These samples were tested as catalysts for the transesterification of glycerol with dimethyl carbonate to glycerol carbonate. After 3h of reaction, all catalysts showed high glycerol conversion (70–84%) and moderate selectivity values to glycerol carbonate (52–65%) accompanied by the formation of low amounts of glycidol (7–15%). These results are very interesting taking into account the low specific surface area of these catalysts (7–25m2/g). No significant catalytic differences were observed between the catalysts. This can be due to the similar surface and basic characteristics observed for all of them. By increasing the reaction time, an increase of conversion was observed arriving practically to total conversion after 24h of reaction, with selectivity to glycerol carbonate in the range 65–75%. Several catalytic reuses favoured the decarboxylation of glycerol carbonate resulting in the formation of higher amounts of glycidol (30%) but still maintaining high selectivity values to glycerol carbonate (70%).
Graphical abstract
HighlightsSynthesized CaAl-LDHs catalysts had similar surface and basic properties.CaAl-LDHs catalysts were highly active for the conversion of glycerol.CaAl-LDHs catalysts led to significant selectivity values to glycerol carbonate.Catalytic reuse favoured decarbonylation of glycerol carbonate to glycidol.
CaAl-layered double hydroxides as active catalysts for the transesterification of glycerol to glycerol carbonate
Granados-Reyes, Judith (author) / Salagre, Pilar (author) / Cesteros, Yolanda (author)
Applied Clay Science ; 132-133 ; 216-222
2016-06-13
7 pages
Article (Journal)
Electronic Resource
English
Ultrasound-assisted reconstruction and delamination studies on CaAl layered double hydroxides
| Online Contents | 2015