Articles written in Journal of Chemical Sciences

    • Preparation, characterization, and post-synthetic modification of layered MCM-22 zeolite precursor


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      Hydrothermal synthesis of MCM-22(P) was carried out with two different silica sources, colloidal silica (28%) and silicic acid with different gel composition. The synthesis was carried out in stirring and static conditions with different crystallization time. MCM-22(P) modified with swelling-sonication method resultedin swollen MCM-22, while alkali treatment yielded desilicated MCM-22. The materials were characterized by X-ray diffraction, low-angle XRD, FE-SEM-EDX, FT-IR, TGA, N₂ adsorption and NH₃-TPD analysis. The results revealed that MCM-22 has a layered sphere, doughnut like morphology and after modification, swollen and broken sphere was observed. Physicochemical analysis revealed that the materials’ mesoporosity increased and acidity also changed. Energy dispersive X-ray analysis revealed the high amount of desilicationin alkali-treated MCM-22(P).

    • Nano-sized Silicalite-1: novel route of synthesis, metal impregnation and its application in selective oxidation of toluene


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      The novel route of synthesis and catalytic performance of nano-sized Silicalite-1 are presented. Nano-sized Silicalite-1 was initially obtained from a clear solution using sodium silicate as silica source and tetrapropylamonium hydroxide as a template. The effects of silica source on the product yield, purity, crystallization rate and crystallinity were investigated. Effect of seeds in the synthesis was also studied. Nucleation time decreased to6hfrom24husing 4% seed, with yield and crystallinity 70% and 90%, respectively. The catalyst was characterized by XRD, FE-SEM, TG, FITR and N2 adsorption–desorption techniques. Transition metals like Fe, Cu and Mo were impregnated by wet impregnation method. Cu-impregnated nanosized Silicalite-1 was found to be highly active for the oxidation of toluene with H2O2.

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