Tin Grafted on Modified Alumina-Catalyzed Isomerisation of Glucose to Fructose

Abstract

The present study focuses on designing a catalyst based on hot water treated alumina (Al2O3-HWT) for the conversion of glucose to fructose. The glucose isomerisation reactions are performed with tin incorporated on parent Al2O3 and Al2O3-HWT in methanol. 0.5 wt% Sn/Al2O3-HWT affords a combined yield of fructose and methylfructoside (30.4%) which is two-fold higher than that obtained with 0.5wt% Sn/Al2O3 (15.1%), implying the importance of hot water treatment of Al2O3. Al2O3-HWT shows a very broad peak centred around 3440 cm-1, which could be assigned to OH stretching band of gibbsite, γ-Al(OH)3 which significantly diminished after solid state ion-exchange with SnCl4.5H2O (0.5 wt% Sn/Al2O3-HWT). UV-Vis diffused reflectance spectrum of 0.5 wt% Sn/Al2O3-HWT displays a peak centered at 241 nm, which can be ascribed to the incorporation of tin into the alumina network. XRD patterns of 0.5, 3 and 5 wt% Sn/Al2O3-HWT show that no peak corresponding to SnO2 is formed. Importantly, 0.5wt% SnO2/Al2O3-HWT exhibits a low activity, giving 13.2% of the total yield of fructose and methylfructoside, respectively, compared to 0.5wt% Sn/Al2O3-HWT (30.4% fructose), signifying the role of incorporated tin into the alumina network.