Facile preparation of Sn-β zeolites by post-synthesis (isomorphous substitution) method for isomerization of glucose to fructose

Sn-β zeolites were facilely synthesized by a post-synthesis method consisting of two steps, i.e., heteroatom removal and isomorphous substitution by reaction with SnCl₄. This significantly shortened the Sn-β zeolite preparation time from the previously reported 40 d to less than 1 d. It was shown that Sn-β samples prepared using the post-synthesis method had higher Sn contents than that prepared using a hydrothermal method. The as-synthesized Sn-β zeolites were tested in the isomerization of glucose to fructose in aqueous media. The effects of reaction temperature, reaction time, catalyst amount, solvent, and halide additive on the isomerization reaction over Sn-Al-β zeolites were studied in detail. Under the optimized conditions, the yield of fructose reached a maximum of ~43%. The catalysts can be reused without loss of activity after regeneration by calcination.