Y. Teraoka et al., Synthesis and characterization of tin oxide-modified mesoporous silica by the repeated post-grafting of tin chloride, MICROP M M, 48(1-3), 2001, pp. 151-158
Modification of mesoporous silica with tin oxide was investigated by the re
peated post-grafting method, which consisted of the repetition of the cycle
of hydroxylation of the surface, grafting of tin(IV) chloride through the
reaction with surface hydroxyl groups and calcination in air. The singly Sn
O2-modified material showed extremely high thermal stability up to 950 degr
eesC as well as the stability against the treatment in basic solution (pH =
10). With increasing the number of cycles, XRD peak intensity characterist
ic to the hexagonal mesophase decreased gradually, but the mesoporous struc
ture was maintained up to the third modification. The optical absorption du
e to tin oxide was emerged by the modification and its absorbance increased
with an increase in the modification cycles. The repeated modification wit
h tin oxide caused progressive decreases in specific surface area, mesopore
volume and diameter, while no significant change of the hexagonal cell par
ameter was observed. It was suggested from the enhanced stabilities and the
pore-structure change that inner wall and outer surfaces of the mesoporous
silica was progressively coated with the tin oxide layer, (C) 2001 Elsevie
r Science B.V. All rights reserved.