576-08-9Relevant articles and documents
Tuning Ca-Al-based catalysts' composition to isomerize or epimerize glucose and other sugars
Ventura, Maria,Cecilia, Juan A.,Rodríguez-Castellón, Enrique,Domine, Marcelo E.
, p. 1393 - 1405 (2020/03/11)
One of the key reactions to achieve good productivity in the transformations of cellulose derived from biomass feedstocks is the isomerization of glucose to fructose, the latest being the platform molecule for obtaining other important derivatives. In this work, Ca-Al containing catalysts based on hydrotalcite-type derived materials were used to perform the selective isomerization of glucose to fructose, and the selective epimerization of glucose to mannose, using water as the solvent under mild reaction conditions. The catalysts showed high activity (conversion = 51-87%), and excellent selectivity (63-88%) towards fructose, compared with the current industrial process based on the glucose transformation via biocatalysis. It was also possible to modulate the selectivity towards fructose or mannose by tuning the amount of basic sites of the catalysts and their composition. The combination of basic and acid sites present in the Ca-Al-based catalysts plays a key role in the reaction, a fact that is discussed in the text together with other important operational parameters. The stability and recyclability of the catalysts were tested, detecting only a small activity loss after 5 consecutive runs. The synthesis of the catalysts and their characterization are also discussed since they are one of the few cases found in the literature of this kind of hydrotalcite-type material with such a high level of Ca incorporation. Some green metrics, such as E-factor, have been calculated to evaluate our system as an environmentally friendly process.
Influence of reaction conditions on the selectivity of the synthesis of lactulose with microbial β-galactosidases
Guerrero, Cecilia,Vera, Carlos,Plou, Francisco,Illanes, Andres
experimental part, p. 206 - 212 (2012/07/13)
Commercial β-galactosidase preparations from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae were evaluated as catalysts for the synthesis of lactulose. Among them, the enzyme from A. oryzae was selected for further studies. The effect of reaction conditions was then studied on product composition during the kinetically controlled synthesis of lactulose by transgalactosylation with A. oryzae β-galactosidase. Product composition was not affected by pH, temperature, total initial concentration of sugar (lactose plus fructose) and enzyme to substrate ratio within the ranges studied. However, lactose to fructose ratio strongly influenced product composition being then possible to control the lactulose to galacto-oligosaccharide ratio within ample margins. Maximum lactulose yield (0.282 g of lactulose per g initial lactose) was obtained using 1/8 lactose to fructose molar ratio, 50% (w/w) total initial sugars, 40 °C, pH 4.5 and enzyme to initial lactose ratio equivalent to 200 IU/g.
