TY - JOUR
T1 - Enthalpies of formation of microporous titanosilicates ETS-4 and ETS-10
AU - Xu, Hongwu
AU - Zhang, Yiping
AU - Navrotsky, Alexandra
N1 - Funding Information:
We thank Bob Haushalter for allowing us to use his synthesis laboratory at the NEC Research Institute and Martin Wilding for performing the microprobe analysis. This work was supported by the National Science Foundation (grant no. DMR-97-31782) and the Department of Energy Environmental Management Science Program (grant no. FG07-97ER45674).
PY - 2001/10
Y1 - 2001/10
N2 - The energetics of microporous titanosilicates ETS-4 (K0.61Na1.09Ti1.10Si4.98 O13 - 2.89H2O) has been investigated by high-temperature drop solution calorimetry using lead borate as the solvent at 974 K. Combining the measured heats of drop solution with the published enthalpies of drop solution and formation for the constituent oxides, the standard enthalpies of formation from the oxides (ΔH0f.ox) and from the elements (ΔH0f.e1) for both phases were derived for the first time. The obtained values (in kJ/mol) are as follows: ΔH0f.ox(ETS-4) = -818.5 ± 13.1, ΔH0f.e1(ETS-4) = - 14, 642.8 ± 15.9, ΔH0f.ox(ETS-10) = -262.2 ± 3.1, and ΔH0f.e1(ETS-10) = -6995.2 ± 6.1. Comparison between the ΔH0f.ox (or ΔH0f.e1) values of the two phases suggests that ETS-4 is thermodynamically more stable than ETS-10 with respect to the oxides (or the elements) at 298 K and 1 atm. This behavior can largely be attributed to the higher degree of hydration of ETS-4 than that of ETS-10.
AB - The energetics of microporous titanosilicates ETS-4 (K0.61Na1.09Ti1.10Si4.98 O13 - 2.89H2O) has been investigated by high-temperature drop solution calorimetry using lead borate as the solvent at 974 K. Combining the measured heats of drop solution with the published enthalpies of drop solution and formation for the constituent oxides, the standard enthalpies of formation from the oxides (ΔH0f.ox) and from the elements (ΔH0f.e1) for both phases were derived for the first time. The obtained values (in kJ/mol) are as follows: ΔH0f.ox(ETS-4) = -818.5 ± 13.1, ΔH0f.e1(ETS-4) = - 14, 642.8 ± 15.9, ΔH0f.ox(ETS-10) = -262.2 ± 3.1, and ΔH0f.e1(ETS-10) = -6995.2 ± 6.1. Comparison between the ΔH0f.ox (or ΔH0f.e1) values of the two phases suggests that ETS-4 is thermodynamically more stable than ETS-10 with respect to the oxides (or the elements) at 298 K and 1 atm. This behavior can largely be attributed to the higher degree of hydration of ETS-4 than that of ETS-10.
KW - ETS-10
KW - ETS-4
KW - Energetics
KW - Enthalpy of formation
KW - Titanosilicate
UR - http://www.scopus.com/inward/record.url?scp=0035477260&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035477260&partnerID=8YFLogxK
U2 - 10.1016/S1387-1811(01)00388-2
DO - 10.1016/S1387-1811(01)00388-2
M3 - Article
AN - SCOPUS:0035477260
SN - 1387-1811
VL - 47
SP - 285
EP - 291
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
IS - 2-3
ER -