TY - JOUR
T1 - Energetics of Alkali and Alkaline Earth Ion-Exchanged Zeolite A
AU - Sun, Hui
AU - Wu, Di
AU - Liu, Kefeng
AU - Guo, Xiaofeng
AU - Navrotsky, Alexandra
N1 - Funding Information:
This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Grant DE-FG02-05ER15667. H.S. thanks the Natural Science Foundation of Shanghai for the financial support (No. 16ZR1408100), and the China Scholarship Council for the State Scholarship Fund (No. 201308310077). D.W. acknowledges the institutional funds from the Gene and Linda Voiland School of Chemical Engineering and Bioengineering at Washington State University.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/7/21
Y1 - 2016/7/21
N2 - Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential (Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO2 (Mg-A). The formation enthalpies from oxides (25 °C) range from -93.71 ± 1.77 (K-A) to -48.02 ± 1.85 kJ/mol per TO2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from -47.99 ± 1.20 (Ba-A) to -26.41 ± 1.71 kJ/mol per TO2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. The formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.
AB - Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential (Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO2 (Mg-A). The formation enthalpies from oxides (25 °C) range from -93.71 ± 1.77 (K-A) to -48.02 ± 1.85 kJ/mol per TO2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from -47.99 ± 1.20 (Ba-A) to -26.41 ± 1.71 kJ/mol per TO2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. The formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.
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U2 - 10.1021/acs.jpcc.6b04840
DO - 10.1021/acs.jpcc.6b04840
M3 - Article
AN - SCOPUS:84979642694
SN - 1932-7447
VL - 120
SP - 15251
EP - 15256
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 28
ER -