Synthesis of Hierarchical Silicoaluminophosphate (SAPO) Molecular Sieves by Post‐Synthetic Modification and Their Catalytic Application

Abstract Silicoaluminophosphates SAPO‐34 (CHA topology) and SAPO‐5 (AFI topology) molecular sieves are selectively prepared by hydrothermal method using templates tetraethylammonium hydroxide and triethylamine, respectively and suitably modified. Hierarchical SAPO‐34 & SAPO‐5 catalysts were post‐synthetically prepared by facile acid (HNO 3 and HCl) and base (NaOH) etching. X‐ray diffraction (XRD), Thermogravimetric analysis (TG), FT‐IR and Scanning Electron Microscope (SEM) were employed to investigate structural changes of the molecular sieves. Hierarchical SAPO‐34 & SAPO‐5 were used for the ring opening reaction of propylene oxide with morpholine producing the corresponding β‐amino alcohols, and catalytic activity of the acid‐treated SAPO‐34 & SAPO‐5 was compared with that of alkali treated counterparts. The catalytic performance of the acid treated materials was found better than the base treated one. 91 % conversion was achieved using acid treated SAPO‐34, whereas 74 % conversion was achieved using alkali treated SAPO‐34.