TY - JOUR
T1 - The states of vanadium species in V-SBA-15 synthesized under different pH values
AU - Gao, Fei
AU - Zhang, Yanhua
AU - Wan, Haiqin
AU - Kong, Yan
AU - Wu, Xingcai
AU - Dong, Lin
AU - Li, Baiqin
AU - Chen, Yi
PY - 2008/4/15
Y1 - 2008/4/15
N2 - V-SBA-15 (nSi/V ≈ 10) mesoporous molecular sieves have been synthesized in different pH-value medias and characterized by XRD, N2 adsorption, TEM, UV-vis, Raman, FT-IR, ESR, and NH3-absorbed in situ FT-IR techniques. Results indicated that the pH value played an important role on the states of vanadium species in the prepared materials. As the pH value increased, the amount of the crystalline vanadium oxides decreased, the incorporated vanadium species with isolated tetrahedral (V5+) and square pyramidal coordination (VO2+) increased accordingly. At pH = 3.0, vanadium species were mainly in the silica framework and formed stronger acid sites, it seems to suggest that the linear configuration V5+-ONH3H+-O-V4+ groups have been formed after ammonia was adsorbed. However, for the samples synthesized at the low pH values, the crystalline vanadium oxides existed and the amount of the dispersed tetrahedral vanadium species decreased, which caused the weaker acid sites.
AB - V-SBA-15 (nSi/V ≈ 10) mesoporous molecular sieves have been synthesized in different pH-value medias and characterized by XRD, N2 adsorption, TEM, UV-vis, Raman, FT-IR, ESR, and NH3-absorbed in situ FT-IR techniques. Results indicated that the pH value played an important role on the states of vanadium species in the prepared materials. As the pH value increased, the amount of the crystalline vanadium oxides decreased, the incorporated vanadium species with isolated tetrahedral (V5+) and square pyramidal coordination (VO2+) increased accordingly. At pH = 3.0, vanadium species were mainly in the silica framework and formed stronger acid sites, it seems to suggest that the linear configuration V5+-ONH3H+-O-V4+ groups have been formed after ammonia was adsorbed. However, for the samples synthesized at the low pH values, the crystalline vanadium oxides existed and the amount of the dispersed tetrahedral vanadium species decreased, which caused the weaker acid sites.
KW - In situ FT-IR
KW - SBA-15
KW - State
KW - Synthesis
KW - Vanadium
UR - http://www.scopus.com/inward/record.url?scp=39849109831&partnerID=8YFLogxK
U2 - 10.1016/j.micromeso.2007.06.041
DO - 10.1016/j.micromeso.2007.06.041
M3 - 文章
AN - SCOPUS:39849109831
SN - 1387-1811
VL - 110
SP - 508
EP - 516
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
IS - 2-3
ER -