TY - JOUR
T1 - Impact of aqueous medium on zeolite framework integrity
AU - Vjunov, Aleksei
AU - Fulton, John L.
AU - Camaioni, Donald M.
AU - Hu, Jian Z.
AU - Burton, Sarah D.
AU - Arslan, Ilke
AU - Lercher, Johannes A.
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/5/12
Y1 - 2015/5/12
N2 - In this work, Al K-edge extended X-ray absorption fine structure and 27Al MAS NMR spectroscopies in combination with DFT calculations are used to determine both qualitative and quantitative structural changes of two well-characterized samples with the BEA structure. The effects of various properties, including Al concentration, Al distribution, particle size, and structural defects, on zeolite stability are explored. As the samples are degraded by treatment in hot liquid water, the local structure about the Al T-site remains mostly intact, including the Al-O-Si angles and bond distances, while the crystalline structure as measured by XRD and STEM is disrupted. The combined data suggests the crystallinity decreases via selective hydrolysis of the T1- and T2-sites that form the 4-member rings of the zeolite framework. The hydrolysis eventually leads to the dissolution of the T-sites followed by reprecipitation on the particle surface resulting in amorphization of the sample.
AB - In this work, Al K-edge extended X-ray absorption fine structure and 27Al MAS NMR spectroscopies in combination with DFT calculations are used to determine both qualitative and quantitative structural changes of two well-characterized samples with the BEA structure. The effects of various properties, including Al concentration, Al distribution, particle size, and structural defects, on zeolite stability are explored. As the samples are degraded by treatment in hot liquid water, the local structure about the Al T-site remains mostly intact, including the Al-O-Si angles and bond distances, while the crystalline structure as measured by XRD and STEM is disrupted. The combined data suggests the crystallinity decreases via selective hydrolysis of the T1- and T2-sites that form the 4-member rings of the zeolite framework. The hydrolysis eventually leads to the dissolution of the T-sites followed by reprecipitation on the particle surface resulting in amorphization of the sample.
UR - http://www.scopus.com/inward/record.url?scp=84929192779&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.5b01238
DO - 10.1021/acs.chemmater.5b01238
M3 - Article
AN - SCOPUS:84929192779
SN - 0897-4756
VL - 27
SP - 3533
EP - 3545
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 9
ER -