Synthesis and characterization of Fe-containing mesoporous molecular sieves using primary amine as template

We synthesized and characterized Fe - containing hexagonal mesoporous silic a (FeHMS) molecular sieves by means of some modem physico - chemiscal techn iques (XRD, SEM, TEM, BET, TG/DTA, FT LR, EPR, Mossbauer spectroscopy, etc. ), together with NH3 - TPD. We found more iron still retain in the framewor k after removal of the surfactant. The particle of FeHMS is smaller than th at of SiHMS, and its surface is smoother. The pore size distribution of FeH MS reveals that there are two type mesopores, with diameters being 2 . 5nm and 10nm, respectively. It is found that Fe is mainly in the tetrahedral co ordinated framework in as - synthesized samples. After removal of the templ ate by calcination, a part of Fe transfers to the wall surface. In case of using acidified alcohol to extract surfactant, it is more effective to reta in Fe in tetrahedral coordinated framework. Fe species on wall surface are of high dispersion when removing the surfactant at high temperature. The re sults indicate that the introduction of Fe could improve the hydrothermal s tability. It seems that the octahedral Fe (III) species is responsible for the above improvement. Owing to the thicker wall, FeHMS appears to possess better thermal and hydrothermal stability than FeMCM - 41.