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.
MCM type mesoporous silica materials can be used as potential catalysts with appropriate functionalization, for increasing selectivity and yield of the desired products. Co‐condensation or post‐synthesis treatment is the most common process of surface functionalization of mesoporous materials for the introduction of catalytic groups to their internal pore surfaces. In this work two different functional moieties were introduced on the surface of mesoporous material; one, a base functional group (3‐aminopropyl)triethoxysilane (APTES) and another, an acid functional group (3‐mercaptopropyl)triethoxysilane (MPTES). The materials were characterized thoroughly by powder XRD, BET, FT‐IR, TGA, NMR, SEM, TEM, etc. The results confirmed successful grafting of both the functional groups. The functionalized materials were tested in ring opening of different oxiranes; and the base functionalized MCM‐48 was found to be catalytically more active than acid functionalized material and was correlated mechanistically. Conversion of morpholine and piperidine with base functionalized material was found to be 93 and 91 %, respectively; and with acid functionalized material, 52 % of conversion of morpholine and 57 % conversion of piperidine was observed. Amine modified mesoporous MCM‐48 and MCM‐41 were found to be totally heterogeneous in nature and the catalysts were reusable up to 4 times without leaching.
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