文献类型：期刊文献

英文题名：Energetics of sodium-calcium exchanged zeolite A

作者：Sun, H.[1];Wu, D.[2,3];Guo, X.[2,3];Shen, B.[1];Navrotsky, A.[2,3]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Univ Calif Davis, Peter A Rock Thermochem Lab, Davis, CA 95616 USA;[3]Univ Calif Davis, NEAT ORU, Davis, CA 95616 USA

年份：2015

卷号：17

期号：17

起止页码：11198

外文期刊名：PHYSICAL CHEMISTRY CHEMICAL PHYSICS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000353338800010)】；

基金：H.S. is grateful to the National Natural Science Foundation of China for the financial support under the National Natural Science Fund for Young Scholar (No. 21201063), the Ministry of Education of Republic of China for the financial support under the Research Fund for the Doctoral Program of Higher Education of China (RFDP) (No. 20110074120020) and the Fundamental Research Funds for the Central Universities, and the China Scholarship Council for the State Scholarship Fund (No. 201308310077). The calorimetric work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, grant DEFG02-97ER14749.

语种：英文

摘要：A series of calcium-exchanged zeolite A samples with different degrees of exchange were prepared. They were characterized by powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). High temperature oxide melt drop solution calorimetry measured the formation enthalpies of hydrated zeolites CaNa-A from constituent oxides. The water content is a linear function of the degree of exchange, ranging from 20.54% for Na-A to 23.77% for 97.9% CaNa-A. The enthalpies of formation (from oxides) at 25 degrees C are -74.50 +/- 1.21 kJ mol(-1) TO2 for hydrated zeolite Na-A and -30.79 +/- 1.64 kJ mol(-1) TO2 for hydrated zeolite 97.9% CaNa-A. Dehydration enthalpies obtained from differential scanning calorimetry are 32.0 kJ mol(-1) H2O for hydrated zeolite Na-A and 20.5 kJ mol(-1) H2O for hydrated zeolite 97.9% CaNa-A. Enthalpies of formation of Ca-exchanged zeolites A are less exothermic than for zeolite Na-A. A linear relationship between the formation enthalpy and the extent of calcium substitution was observed. The energetic effect of Ca-exchange on zeolite A is discussed with an emphasis on the complex interactions between the zeolite framework, cations, and water.