TY - JOUR
T1 - Hydrothermal Stability of One-Dimensional Pore ZSM-22 Zeolite in Hot Water
AU - Jamil, Anas K.
AU - Muraza, Oki
AU - Osuga, Ryota
AU - Shafei, Emad N.
AU - Choi, Ki Hyouk
AU - Yamani, Zain H.
AU - Somali, Ali
AU - Yokoi, Toshiyuki
N1 - Funding Information:
We acknowledge the funding provided by Saudi Aramco for supporting this work through project contract number 6600011900 as part of the Oil Upgrading theme at King Fahd University of Petroleum and Minerals.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/10/13
Y1 - 2016/10/13
N2 - The hydrothermal stability of 1-D medium pore zeolites ZSM-22 with different nominal Si/Al ratios (30, 46, 80, and 100) was investigated in hot liquid water environments at different temperatures (100, 150, 200, and 250 °C) and different exposure times (6, 12, 36, 72, and 144 h). The changes in the zeolite structure, phase transformation, and textural properties were characterized by X-ray diffraction, scanning electron microscopy, 27Al and 29Si magic-angle spinning nuclear magnetic resonance, temperature-programmed desorption of ammonia, IR spectra, and X-ray fluorescence. After the treatment in a hot water environment, TON framework suffered from desilication (silicon extraction), phase transformation, and crystallinity change. The degree of desilication via siloxane hydrolysis is dependent on the treatment time and temperature. At high temperature (250 °C), severe desilication, textural properties degradation, and formation of extra-framework Al species (EFAL) were observed. This formed EFAL worked as a covering layer protecting the venerable Si bonds and mitigated further leaching of Si species from TON framework with time progress. On the contrary, selective removal of Si species at temperatures lower than 250 °C was observed without the appearance of EFAL.
AB - The hydrothermal stability of 1-D medium pore zeolites ZSM-22 with different nominal Si/Al ratios (30, 46, 80, and 100) was investigated in hot liquid water environments at different temperatures (100, 150, 200, and 250 °C) and different exposure times (6, 12, 36, 72, and 144 h). The changes in the zeolite structure, phase transformation, and textural properties were characterized by X-ray diffraction, scanning electron microscopy, 27Al and 29Si magic-angle spinning nuclear magnetic resonance, temperature-programmed desorption of ammonia, IR spectra, and X-ray fluorescence. After the treatment in a hot water environment, TON framework suffered from desilication (silicon extraction), phase transformation, and crystallinity change. The degree of desilication via siloxane hydrolysis is dependent on the treatment time and temperature. At high temperature (250 °C), severe desilication, textural properties degradation, and formation of extra-framework Al species (EFAL) were observed. This formed EFAL worked as a covering layer protecting the venerable Si bonds and mitigated further leaching of Si species from TON framework with time progress. On the contrary, selective removal of Si species at temperatures lower than 250 °C was observed without the appearance of EFAL.
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U2 - 10.1021/acs.jpcc.6b04980
DO - 10.1021/acs.jpcc.6b04980
M3 - Article
AN - SCOPUS:84991694137
VL - 120
SP - 22918
EP - 22926
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 40
ER -