Adsorption properties of glucose and isomaltose on different BEA zeolites
The adsorption properties of monosaccharide glucose and disaccharide isomaltose have been investigated on BEA zeolites with different moduli for a reaction-integrated adsorption system. For BEA-type zeolites from Süd- Chemie the moduli Si/AlD12.5, 75, and 225 were compared and showed a maximum for isomaltose adsorption on Si/Al D 75. Adsorption models of Langmuir and Toth were used for fitting of the detected data and compared. Equilibrium measurements at different temperatures allowed the calculation of the adsorption enthalpy. For module Si/Al D 75 adsorption enthalpy δhAd was -27:5 kJ mol-1 using Langmuir and -26:3 kJ mol-1 in the case of Toth's model. For glucose only -13:3 kJ mo-1 was obtained, indicating a weaker adsorption compared to isomaltose. For an enzymatic production system, BEA150 (Süd-Chemie) and HSZ-980HOA (Tosoh Corporation) were compared. The adsorption equilibrium constant Ki;L is 14:9mLg-1 on BEA 150 and 1:79mLg-1 on HSZ-980HOA. Hence, HSZ-980HOA shows a three-fold faster desorption, which was determined in desorption kinetics. Despite nearly identical loading under production conditions, BEA 150 reaches a yield of 64% for purification of isomaltose compared to 43% for HSZ-980HOA. © de Gruyter 2012.