Effect of Si/Al ratio and a secondary hydrothermal treatment on the properties of Al-MSU-SFAU

This work reexamines the preparation condition of Al-MSU-SFAU, which is prepared with an assembly method from zeolite Y seed colloidal, and reveals the effect of Si/Al ratio and a secondary hydrothermal treatment on the property of the material, e.g. the texture, the hydrothermal stability, the acidity and the catalytic activity. With the specific condition for preparing Al-MSU-SFAU, the samples with high Si/Al atomic ratios are uniform, but have no crystalline structure and low hydrothermal stability. The samples with Si/Al <5 contain a significant amount of micropores. However, they are also instable and are the mixtures of zeolite Y and mesoporous material. A secondary hydrothermal treatment destroys a part of the mesopores for all the samples irrespective of the Si/Al ratios but reforms the micropores, specifically improves the micropore volume and surface area for the sample with Si/Al = 5. This sample has the long expected micro/meso composite porous structure with higher hydrothermal stability and acidity.