TY - JOUR
T1 - Effect of the SiO2/TiO2 ratio on the solid acidity of SiO2-TiO2/montmorillonite composites
AU - Kameshima, Yoshikazu
AU - Koike, Tomohisa
AU - Isobe, Toshihiro
AU - Nakajima, Akira
AU - Okada, Kiyoshi
N1 - Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/9
Y1 - 2009/9
N2 - 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.
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.
KW - A. Composites
KW - A. Layered compounds
KW - B. Intercalation reactions
KW - D. Surface properties
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U2 - 10.1016/j.materresbull.2009.05.005
DO - 10.1016/j.materresbull.2009.05.005
M3 - Article
AN - SCOPUS:67651172774
SN - 0025-5408
VL - 44
SP - 1906
EP - 1909
JO - Materials Research Bulletin
JF - Materials Research Bulletin
IS - 9
ER -