Synthesis of Fe-SBA-15 mesoporous material

Abstract

A new mesoporous material, namely Fe-SBA-15, was synthesized by static hydrothermal method at the temperature of 100 ℃. The methodology for synthesis of Fe-SBA-15 was studied. Effect of pH of gel (-0.30 to 3.0), type of iron source (Fe2+ and Fe3+), and Si/Fe ratio in gel (180 and 90) on formation of Fe-SBA-15 structure were studied. XRD was used for structural determination, SEM for crystal morphology, and ESR for iron coordination. It was found that gel aging is an essential step to induce the hexagonal structure of SBA-15 and the pre-mixing of iron source and silica source in acid solution is required to incorporate iron into the framework of SBA-15. Morphology of Fe-SBA-15 was found to be rope-like and worm-like shape depending on the pH of the synthesis gel. Tetrahedral and octahedral coordinations of iron atoms to framework silica were observed. Iron can be incorporated at higher amount with increasing pH of gel. There was no significant difference in using Fe3+ and Fe2+ as iron source. The Fe-SBA-15 material synthesized in this work is found active for conversion of methanol to hydrocarbons. Formation of olefinic products is favored at the temperature of 300 ℃ while formation of methane is more predominant at higher temperature.