Unambiguously distinguishing Si[3Si,1Al] and Si[3Si,1OH] stuctural units in zeolite by 1H/29Si/27Al triple resonance solid state NMR spectroscopy.
We present an experimentally feasible triple-resonance NMR method that establishes the correlation among three different nuclei, avoiding the difficulty to directly explore the weak coupling between two NMR nuclei, such as (29)Si and (27)Al. Using this method, we are able to give an unambiguous assignment to the various peaks in (29)Si CP NMR spectrum of MCM-22 zeolite and discriminate (29)Si signals from SiOHAl and SiOH groups. In addition, in combination with (1)H/(27)Al double-resonance technique, the (1)H/(27)Al/(29)Si triple-resonance experiment suggests the presence of two different kinds of Brönsted acid sites in H-MCM-22 zeolite.
Luo
Qing
Q
Wuhan Institute of Physics and Mathematics, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, The Chinese Academy of Sciences, Wuhan City, Hubei Province 430071, PR China.
Yang
Jun
J
Hu
Wei
W
Zhang
Mingjin
M
Yue
Yong
Y
Ye
Chaohui
C
Deng
Feng
F