Effect of addition of alkali metal salts in hydrothermal synthesis and post heat-treatment on porosity of SBA-15

Masaki Okamoto, Yuko Fukukita, Masaki Haga, Kazuhisa Toyofuku, Naoki Mimura

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

SBA-15 was hydrothermally synthesized at 80 °C for 48 h, and then the surfactant template for mesopore formation was removed by extraction with ethanol, washing with nitric acid, and heating at 200 °C. Addition of alkali metal chlorides to a synthesis gel of SBA-15 increased its mesopore diameter in the following order: no added salt < LiCl < KCl < CsCl. The micropore volume did not change with the addition of any alkali metal and was around 0.17 mL g-1. These results suggest that alkali metal salt is inside the mesopore with a micelle template. When a small amount of potassium chloride was impregnated in SBA-15 after extraction and washing, micropore volume reduced almost to zero with heating at 400 °C in dry air, and the mesopore diameter and pore wall thickness were reduced by a larger amount than for non-impregnated SBA-15. It is likely that the micropores in the mesopore wall vanish due to condensation of silanols and/or reconstruction of siloxane bonds on the micropore wall, which are catalyzed by alkali metal halides.

Original languageEnglish
Pages (from-to)135-140
Number of pages6
JournalJournal of Porous Materials
Volume16
Issue number2
DOIs
Publication statusPublished - 2009 Apr 1
Externally publishedYes

Keywords

  • Alkali metal salt
  • Heat treatment
  • Micropore
  • Ordered mesoporous silica
  • SBA-15

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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