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Cr-doped Zr, Si-mesoporous molecular sieves as catalysts of CH<inf>2</inf>Cl<inf>2</inf> oxidation

Abstract:

Zirconium-containing mesoporous silica of nominal Si/Zr ratio in the range 40-5 have been synthesized using dodecylamine as a structure-directing surfactant. The samples were characterized with PXRD, SEM/EDX, BET, CEC measurement and chemical analysis. The materials were used as supports for chromium species incorporated by means of cation exchange procedure. Gradual substitution of Si by Zr in the mesoporous framework results in an increasing structural disorder, increasing cation exchanged capacity and increasing capacity for incorporation of Cr. All Cr-doped ZrMMSx catalyst are active in the deep oxidation of methylene chloride reaching 100% conversion at temperature ≥400°C. The catalytic performance depends strongly on the catalyst composition. The role of particular components in determining the catalytic activity and selectivities to various products is discussed.