The role of aluminum in Sn-Al-beta zeolite catalyzing the conversion of glucose to methyl lactate

The preparation of H-Beta zeolites with different Si/Al ratios (Si/Al=14, Si/Al=288) was obtained by desiliconization and dealumination. Subsequently, Sn-Al-Beta catalysts were prepared by tin grafting and used for the conversion of glucose to methyl lactate. The results indicate that the yield of methyl lactate from the catalyst obtained using the parent H-beta synthesis with a high Si/Al ratio is higher than that of methyl lactate from the parent catalyst with a low initial Si/Al ratio. And the maximum methyl lactate yield of 46.66% was achieved on Sn-Al-Beta (DSi-277). In contrast, the yield of methyl lactate on Sn-Al-Beta (DAl-493) was 24.54%. Results from spectroscopic analysis and probe molecular FTIR indicated that the post-synthesis process altered the structure of the zeolite, which changed its aluminum concentration and existence form (1.8ppm chemical shift), Additionally, when the aluminum interacted with the Sn that had been added to the zeolite, it encouraged the Sn transformation to the high energy state and created the weaker Lewis acid site, as well as more effective action to improve reaction yield.