TY - JOUR
T1 - Enthalpy of formation and dehydration of alkaline earth cation exchanged zeolite beta
AU - Sun, Pingping
AU - Navrotsky, Alexandra
N1 - Funding Information:
We thank Tricat Zeolites GmbH for sending us well characterized zeolite beta samples, Gregory Baxter and Sarah Roeske for assistance in electron microprobe analysis, Ping Yu for NMR analysis. This work is supported by National Science Foundation, Grant DMR 0601892.
PY - 2008/3/1
Y1 - 2008/3/1
N2 - Cationic variants of zeolite beta (Mg-BEA 14, Ca-BEA 14, Sr-BEA 14, Ba-BEA 14, Mg-BEA 4 and Ca-BEA 4) were achieved by alumination and ion exchange processes, and characterized by XRD, NMR and TG-DSC. Mg-BEA 14/Ca-BEA 14, Sr-BEA 14/Ba-BEA 14, and Mg-BEA 4/Ca-BEA 4 have distinct thermal behavior. The low silica zeolites Mg-BEA 4 and Ca-BEA 4 were observed to have octahedral Al atoms and less crystallinity compared with high silica Mg-BEA 14 and Ca-BEA 14. High temperature oxide melt solution calorimetry determined the dehydration enthalpy and the formation enthalpy from the constituent oxides. For alkaline earth zeolite beta with the same Si/Al ratio, both the integral dehydration enthalpy and formation enthalpy from oxides becomes more endothermic with increasing average ionic potential. Mg-BEA 4 and Ca-BEA 4 have very endothermic formation enthalpies, in both dehydrated and hydrated forms, indicating a likely thermodynamic barrier to their direct synthesis, despite the natural occurrence of their analog, tschernichite.
AB - Cationic variants of zeolite beta (Mg-BEA 14, Ca-BEA 14, Sr-BEA 14, Ba-BEA 14, Mg-BEA 4 and Ca-BEA 4) were achieved by alumination and ion exchange processes, and characterized by XRD, NMR and TG-DSC. Mg-BEA 14/Ca-BEA 14, Sr-BEA 14/Ba-BEA 14, and Mg-BEA 4/Ca-BEA 4 have distinct thermal behavior. The low silica zeolites Mg-BEA 4 and Ca-BEA 4 were observed to have octahedral Al atoms and less crystallinity compared with high silica Mg-BEA 14 and Ca-BEA 14. High temperature oxide melt solution calorimetry determined the dehydration enthalpy and the formation enthalpy from the constituent oxides. For alkaline earth zeolite beta with the same Si/Al ratio, both the integral dehydration enthalpy and formation enthalpy from oxides becomes more endothermic with increasing average ionic potential. Mg-BEA 4 and Ca-BEA 4 have very endothermic formation enthalpies, in both dehydrated and hydrated forms, indicating a likely thermodynamic barrier to their direct synthesis, despite the natural occurrence of their analog, tschernichite.
KW - Al coordination
KW - Calorimetry
KW - Formation and dehydration enthalpy
KW - Thermal behavior
KW - Zeolite BEA
UR - http://www.scopus.com/inward/record.url?scp=37349004138&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=37349004138&partnerID=8YFLogxK
U2 - 10.1016/j.micromeso.2007.04.040
DO - 10.1016/j.micromeso.2007.04.040
M3 - Article
AN - SCOPUS:37349004138
SN - 1387-1811
VL - 109
SP - 147
EP - 155
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
IS - 1-3
ER -