Adsorption kinetics of CO2, O2, N2, and CH4 in cation-exchanged clinoptilolite

被引:104
作者
Aguilar-Armenta, G
Hernandez-Ramirez, G
Flores-Loyola, E
Ugarte-Castaneda, A
Silva-Gonzalez, R
Tabares-Munoz, C
Jimenez-Lopez, A
Rodriguez-Castellon, E
机构
[1] Benemerita Univ Autonoma Puebla, Ctr Invest, Fac Ciencias Quim, Puebla 72570, Mexico
[2] Benemerita Univ Autonoma Puebla, Inst Fis Luis Rivera Terrazas, Puebla 72570, Mexico
[3] Univ Malaga, Fac Ciencias, Dept Quim Inorgan, E-29071 Malaga, Spain
来源
JOURNAL OF PHYSICAL CHEMISTRY B | 2001年 / 105卷 / 07期
关键词
D O I
10.1021/jp9934331
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The rate of adsorption of pure CO2, O-2, N-2, and CH4 on natural untreated clinoptilolite-rich volcanic tuff (Cp) from Tehuacan (Puebla, Mexico), and on cation-exchanged clinoptilolite samples (Ca-Cp, K-Cp, and Na-Cp) has been measured at 20 degreesC using a glass high-vacuum volumetric apparatus. The X-ray diffraction pattern of Cp showed that the main crystalline phases correspond to clinoptilolite-heulandite and minor amounts of mordenite, cristobalite, feldspar (albite), quartz, smectite, and opal. The adsorption rates of gases in the initial period (t < 180 s) were measured with a custom acquisition data card capable of registering pressure and time data five times per second, simultaneously. The influence of cation exchange on adsorption kinetics of the gases depended on the gas-adsorbent contact time (t). In the initial period, the adsorption rate of all gases on all samples decreased in the order Ca-Cp > K-Cp > Cp > Na-Cp, and the affinity decreased in the order CO2 much greater than N-2 > O-2 > CH4, whereas at equilibrium (t --> infinity s) the adsorption uptake decreased in the sequence CO2 much greater than CH4 > N-2 > O-2. The slow adsorption of methane in Na-Cp was probably due to diffusional difficulties as a result of channel blockage by Na+ cations. By cation exchange of Cp an adsorbent can be tailored for the separation of N-2/O-2, N-2/CH4, and CO2/CH4 mixtures.
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页码:1313 / 1319
页数:7
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