Hydrolysis of fructose and glucose precursors

Hydrolysis of inulin has already been performed in the presence of a zeolite, namely the zeolite LZ-M-8.[11] This catalyst has been found to be extremely selective towards hydrolysis compared with fructose decomposition, thus illustrating the superiority of the zeolite over sulfuric acid or ion-exchange resins as catalysts. As an example, a 96% yield in fmctose was obtained after 15 min at 130 °C starting from 2 ml of a 0.257 mol L 1 inulin solution and 0.25 g of zeolite. 

In the presence of a H-Y zeolite with a Si/Al ratio of 15, we have performed the hydrolysis of other fructose and glucose precursors under operating conditions quite close to those used for sucrose hydrolysis. It was found that aqueous solutions of inulin, maltose, cellobiose and starch (50-l20gL L) were hydrolysed into the corresponding monosaccharides within 30-150 min at temperatures between 90 °C and 150 °C in the presence of 0.5-2.5 g of catalyst in 50 ml of starting solution, with yields of monosaccharides from 92 to 98%.[12] 

From this work, an important feature to be noted was the influence of stereoelectronic effects toward cleavage of / -1,4 (cellobiose) and a-1,4 linkage (maltose)/131 In the presence of zeolites, there is insufficient space inside the channels for conformational changes both in ground and transition states. In such a way, maltose is hydrolysed faster than cellobiose compared with homogeneous or macroporous ion-exchange resin catalysis/71 

In the presence of MCM-41, acidic Mordenites and Beta zeolites with different Si/Al ratios, it has been shown by Abbadi et al 111 that maltose (lg in 50 ml of water, batch reactor, 0.5g of catalyst) was also selectively hydrolysed into glucose at 130°C. For other polysaccharides, such as amylose and starch, the conversion and 

However, for hydrolysis of inulin over a H-Beta zeolite at 100 °C (1 g of inulin in 50 ml of water, batch reactor, 0.25 g of catalyst), a large effect of the nitrogen pressure was observed. Hydrolysis goes to completion within 5 h at 1 bar N2 and within 20 min at 100 bar N2, without any effect on the selectivity of the reaction. 

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C. Moreau, R. Durand, J. Duhamet, and P. Rivalier, Hydrolysis of fructose and glucose precursors in the presence of H-form zeolites, J. Carbohydr. Chem., 16 (1997) 709-714. 

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