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Ferrisilicate and chromium silicalite with MCM-41 type structure have been synthesized and characterized using several spectroscopic techniques. The results of framework IR, ESR and solid-state MAS NMR measurements indicate an isomorphous substitution of Si4+ by iron or chromium ions in the silicalite framework. An absorption band at 960 cm-1 on the IR spectrum, characteristic of the incorporation in the case of titanosilicalites, is observed in both FeMCM-41 and CrMCM-41. Fe(III) and Cr(III) containing MCM-41 molecular sieves were also demonstrated by X-ray powder diffraction, SEM, UV-VIS, TG-DTA, NH3-TPD and chemical analysis. The experimental results indicate that the conceintion of Cr(III)incorporated into framework is lower than that of Fe(III) in silicalites.
Ferrisilicate and chromium silicalite with MCM-41 type structure have been synthesized and characterized using several spectroscopic techniques. The results of framework IR, ESR and solid-state MAS NMR measurements indicate an isomorphous substitution of Si4 + by iron or chromium ions in the silicalite framework. An absorption band at 960 cm -1 on the IR spectrum, characteristic of the incorporation in the case of titanosilicalites, was observed in both FeMCM-41 and CrMCM-41. Fe (III) and Cr (III) containing MCM-41 molecular sieves were also demonstrated by X-ray powder diffraction, SEM, UV-VIS, TG-DTA, NH3-TPD and chemical analysis. The experimental results indicate that the concemtion of Cr (III) incorporated into the framework is lower than that of Fe ) in silicalites.