No abstract

To overcome the rapid deactivation of conventional ZSM-5, novel nanosheet MFI zeolites, with different Si/Al molar ratios were well fabricated. It was found that Si/Al molar ratios, do not just affect acid properties, but also determine the morphologies of nanosheet MFI zeolites by changing a-c plane areas of zeolite nanosheets. In reaction of gas phase glycerol dehydration to acrolein, the nanosheet MFI zeolites were much more active and stable than conventional ZSM-5 catalysts, owing to their suitable acidity and unique nanosheet structure. For nanosheet MFI zeolite, with Si/Al = 50 (NMZ-50), the conversion of glycerol is higher than 99% in the initial 12 h, with an acrolein selectivity of 86.6%, better than most previous reports. This superior stability of NMZ-50 can be ascribed to its low coke deposition rate and improved coke tolerance capacity. Additionally, it is interesting to find that Al contents do not just simply affect acid properties, but also determine morphologies of nanosheet MFI zeolites, and thus influence catalytic performance.