Relation between Morphology and Porous Structure of SAPO-11 Molecular Sieves and Chemical and Phase Composition of Silicoaluminophosphate Gels

Abstract

The formation of silicoaluminophosphate gels using boehmite, Al isopropoxide, and di-n-propylamine as a template of silicoaluminophosphate gels as well as their subsequent crystallization into SAPO-11 molecular sieves was studied in detail using X-ray fluorescence spectroscopy (XRF), powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption–desorption methods. The effect of the chemical and phase composition of silicoaluminophosphate gels on the physicochemical properties of SAPO-11 molecular sieves was shown. The secondary structural units that the AEL lattice is composed of were found to be formed at the initial stage of preparation involving aluminum isopropoxide. Several approaches to control their morphology and secondary porous structure are also proposed.

Keywords

• silicoaluminophosphate gels
• zeolites
• SAPO-11
• crystal morphology
• micro-mesoporous materials