Calorimetric heats of adsorption and adsorption isotherms .2. O-2, N-2, Ar, CO2, CH4, C2H6, and SF6 on NaX, H-ZSM-5, and Na-ZSM-5 zeolites
Calorimetric heats of adsorption and adsorption isotherms .2. O-2, N-2, Ar, CO2, CH4, C2H6, and SF6 on NaX, H-ZSM-5, and Na-ZSM-5 zeolites
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DOI：
10.1021/la960496r
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发表时间：
1996-11-27
期刊：
影响因子：
3.9
通讯作者：
Myers, AL
中科院分区：
文献类型：
--
作者：
Dunne, JA;Rao, M;Myers, AL
用量热计同时测定了一系列体积和四极矩大小递增的气体（Ar、O-2、N-2、CH_4、C_2 H_6、SP_6、CO_2）在不同孔结构和离子类型的吸附剂（NaX、H-ZSM-5、Na-ZSM-5）上的吸附等温线和吸附等温线，并用脱附实验检验了吸附等温线的可逆性。加载的平均实验误差为+/-0.6%;等温吸附热的平均不确定度为+/-0.5kJ/mol。非极性分子（CH_4、C_2 H_6、SF_6）的吸附热在低覆盖度下按NaX、硅质岩、H-ZSM-5、Na-ZSM-5的顺序增加。在高覆盖度下，非极性分子在硅质岩、H-ZSM-5和Na-ZSM-5上的吸附热几乎相同。四极分子CO_2的吸附热按硅沸石、H-ZSM-5、Na-ZSM-5、NaX的顺序增加。根据CO2在Na-ZSM-5中的吸附热与CO2在硅质岩中的吸附热之间的差异，邻近Na+位点的电场为6.2V/nm。
Isosteric heats of adsorption and adsorption isotherms have been measured simultaneously in a calorimeter for a series of gases of increasing size and magnitude of quadrupole moment (Ar O-2, N-2, CH4, C2H6, SP6, CO2) on adsorbents of varying pore structure and ion type (NaX, H-ZSM-5, Na-ZSM-5), Adsorption isotherms have been checked for reversibility by desorption experiments. The average experimental error in loading is +/-0.6%; the average uncertainty in the isoster-ic heat of adsorption is +/-0.5 kJ/mol. Heats of adsorption of nonpolar molecules (CH4, C2H6, SF6) increase in the order NaX, silicalite, H-ZSM-5, Na-ZSM-5 at low coverage. Heats of adsorption of nonpolar molecules are almost identical on silicalite, H-ZSM-5, and Na-ZSM-5 at high coverage. Heats of adsorption of the quadrupolar molecule CO2 increase in the order silicalite, H-ZSM-5, Na-ZSM-5, NaX. The electric field adjacent to Na+ sites is 6.2 V/nm, on the basis of the difference between the heat of adsorption of CO2 in Na-ZSM-5 and the heat of adsorption of CO2 in silicalite.