The Effect of Molar Ratio and Precipitation Time of Mg/Al Hydrotalcite Synthesis on the Isomerization of Glucose into Fructose

Abstract

The substitution of Mg/Al hydrotalcite catalyst over the glucose-isomerase is expected to decrease the space-time and reduce the energy consumption of glucose isomerization into fructose. The quality of the Mg/Al hydrotalcite catalyst is determined during the synthesis process. The synthesis has been carried out in the various Mg/Al molar ratio and precipitation times and observed the catalytic activity in the isomerization. Response Surface Methodology (RSM) is used to analyze statistically the optimum condition of the synthesis process. The Mg/Al molar ratio was 1:1 to 4:1 with a precipitation time of 720-1080 min. The characterization of the Mg/Al hydrotalcite catalyst includes the functional groups of the constituent compounds by FTIR, the crystallinity and particle size by (XRD), and the surface area of the catalyst by BET. The RSM results show the optimum condition of the Mg/Al molar ratio and precipitation time to produce the highest mass catalyst product of Mg/Al hydrotalcite catalyst (3,38 g) is 3.34:1 and 984.85 min. The highest degree of crystallinity obtained is 28.70% with the particle size is 10.19 Å. The highest yield and selectivity of the isomerization process are 56.95% and 91.89%, respectively. By the RSM analytical method, the Mg/Al molar ratio and the precipitation time used in this catalyst synthesis do not give a significant effect on the catalytic activity of the isomerization.