• Key parameters to improve zeolites hierarchization in direct synthesis

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      https://www.ias.ac.in/article/fulltext/boms/043/0288

    • Keywords

       

      Hierarchical ZSM-11; hydrothermal synthesis; soft templates; synthesis parameters; type of base.

    • Abstract

       

      In this study, we propose the generation of micro/mesoporous zeolites with ZSM-11 structure by hydrothermal treatment using tetrabutylammonium hydroxide (TBAOH) as micropore structure directing agent and cetyltrimethylammonium bromide (CTAB) as mesotemplate. From many synthesis parameters evaluated (crystallization time, hydrothermal temperature, CTAB content), the type of base employed in the synthesis gel showed notorious influence in the structure, textural properties and morphology of the micro/mesoporous ZSM-11 zeolites. The samples were characterized by different techniques such as X-ray diffraction, nitrogen adsorption and desorption isotherms, Brunauer–Emmett–Teller surface area, scanning electron microscope, ICP-AES and ${}^{27}$Al MAS NMR. The characterization results revealed that the crystallization time, CTAB content and type of base (NaOH, KOH, Ca(OH)$_2$ and NaCO$_3$) played a dominant role in controlling the formation of both microporous and mesoporous structures. The base employed in the synthesis and its concentration showed important effects on the structure and textural properties of the composite materials. It was found that to obtain the best characteristics in terms of crystallinity and textural parameters, NaOH and KOH should be employed.

    • Author Affiliations

       

      L BONETTO1 L B PIERELLA1 C SAUX1

      1. Centro de Investigacion y Tecnologıa Quımica (CITeQ), UTN – CONICET, Maestro Marcelo Lopez y Cruz Roja Argentina, 5016 Cordoba, Argentina
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