Effect of the SiO2/TiO2 ratio on the solid acidity of SiO2-TiO2/montmorillonite composites

Yoshikazu Kameshima, Tomohisa Koike, Toshihiro Isobe, Akira Nakajima, Kiyoshi Okada

Research output: Contribution to journalArticle

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Abstract

SiO2-TiO2/montmorillonite composites with varying SiO2/TiO2 molar ratios were synthesized and the effect of the SiO2/TiO2 ratio on the solid acidity of the resulting composites was investigated. Four composites with SiO2/TiO2 molar ratios of 0, 0.1, 1 and 10 were synthesized by the reaction of colloidal SiO2-TiO2 particles prepared from alkoxides with sodium-montmorillonite at room temperature. The composites showed slight expansion and broadening of the XRD basal reflection, corresponding to the intercalation of fine colloidal SiO2-TiO2 particles into the montmorillonite sheets and incomplete intercalation to form disordered stacking of exfoliated montmorillonite and colloidal SiO2-TiO2 particles. The colloidal particles crystallized to anatase in the low SiO2/TiO2 composites but remained amorphous in the high SiO2/TiO2 composites. The specific surface areas (SBET) of the composites measured by N2 adsorption ranged from 250 to 370 m2/g, considerably greater than in montmorillonite (6 m2/g). The pore size increased with decreasing SiO2/TiO2 molar ratio of the composites. The NH3-TPD spectra of the composites consisted of overlapping peaks, corresponded to temperatures of about 190 and 290 °C. The amounts of solid acid obtained from NH3-TPD were 186-338 μmol/g in the composites; these values are higher than in the commercial catalyst K10 (85 μmol/g), which is synthesized by acid-treatment of montmorillonite. The present sample with SiO2/TiO2 = 0.1 showed the highest amount of acid, about four times higher than K10.

Original languageEnglish
Pages (from-to)1906-1909
Number of pages4
JournalMaterials Research Bulletin
Volume44
Issue number9
DOIs
Publication statusPublished - Sep 2009
Externally publishedYes

Fingerprint

Bentonite
montmorillonite
Clay minerals
Acidity
acidity
composite materials
Composite materials
Temperature programmed desorption
Intercalation
intercalation
acids
Acids
TiO2-SiO2
alkoxides
Specific surface area
anatase
Titanium dioxide
Pore size
Sodium
sodium

Keywords

  • A. Composites
  • A. Layered compounds
  • B. Intercalation reactions
  • D. Surface properties

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

Effect of the SiO2/TiO2 ratio on the solid acidity of SiO2-TiO2/montmorillonite composites. / Kameshima, Yoshikazu; Koike, Tomohisa; Isobe, Toshihiro; Nakajima, Akira; Okada, Kiyoshi.

In: Materials Research Bulletin, Vol. 44, No. 9, 09.2009, p. 1906-1909.

Research output: Contribution to journalArticle

Kameshima, Yoshikazu ; Koike, Tomohisa ; Isobe, Toshihiro ; Nakajima, Akira ; Okada, Kiyoshi. / Effect of the SiO2/TiO2 ratio on the solid acidity of SiO2-TiO2/montmorillonite composites. In: Materials Research Bulletin. 2009 ; Vol. 44, No. 9. pp. 1906-1909.
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AB - SiO2-TiO2/montmorillonite composites with varying SiO2/TiO2 molar ratios were synthesized and the effect of the SiO2/TiO2 ratio on the solid acidity of the resulting composites was investigated. Four composites with SiO2/TiO2 molar ratios of 0, 0.1, 1 and 10 were synthesized by the reaction of colloidal SiO2-TiO2 particles prepared from alkoxides with sodium-montmorillonite at room temperature. The composites showed slight expansion and broadening of the XRD basal reflection, corresponding to the intercalation of fine colloidal SiO2-TiO2 particles into the montmorillonite sheets and incomplete intercalation to form disordered stacking of exfoliated montmorillonite and colloidal SiO2-TiO2 particles. The colloidal particles crystallized to anatase in the low SiO2/TiO2 composites but remained amorphous in the high SiO2/TiO2 composites. The specific surface areas (SBET) of the composites measured by N2 adsorption ranged from 250 to 370 m2/g, considerably greater than in montmorillonite (6 m2/g). The pore size increased with decreasing SiO2/TiO2 molar ratio of the composites. The NH3-TPD spectra of the composites consisted of overlapping peaks, corresponded to temperatures of about 190 and 290 °C. The amounts of solid acid obtained from NH3-TPD were 186-338 μmol/g in the composites; these values are higher than in the commercial catalyst K10 (85 μmol/g), which is synthesized by acid-treatment of montmorillonite. The present sample with SiO2/TiO2 = 0.1 showed the highest amount of acid, about four times higher than K10.

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