Combined volumetric, infrared spectroscopic and theoretical investigation of CO₂ adsorption on Na-A zeolite

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• 作者：A. Zukal^a ; C.O. Arean^b ; M.R. Delgado^b ; P. Nachtigall^c ; A. Pulido^c ; J. Mayerová ; ^a ; J. ?ejka^a ;   ; ^{jiri.cejka@jh-inst.cas.cz}
• 关键词：Na-A zeolite ; Carbon dioxide ; Adsorption ; Infrared spectroscopy ; Density functional theory
• 刊名：Microporous and Mesoporous Materials
• 出版年：2011
• 出版时间：December 2011
• 年：2011
• 卷：146
• 期：1-3
• 页码：97-105
• 全文大小：858 K

文摘

Adsorption isotherms of carbon dioxide on the Na-A zeolite were measured in the temperature range from 273 to 333 K. Henry’s constants and isosteric adsorption heats calculated from the temperature dependence of CO₂ isotherms were combined with results of the variable temperature IR spectroscopy to obtain a spectroscopic signature of adsorption complexes and corresponding thermodynamic characteristics. The adsorption of CO₂ in Na-A zeolite was also investigated computationally, using a periodic density functional model improved for the proper description of dispersion interactions. Based on a good agreement between experimental and calculated adsorption heats and shifts of asymmetric CO₂ stretching frequency due to adsorption the following model of CO₂/Na-A system is proposed: (i) CO₂ adsorption complexes formed at a low coverage involves interaction of CO₂ with three Na⁺ cations in the LTA supercage; they are characterized by the IR band at 2349 cm^?. (ii) CO₂ adsorption complexes at higher coverages are formed between a pair of Na⁺ cations; they are characterized by the IR band centered at 2360 cm^?. Almost half of the interaction energy between CO₂ and Na-A is due to the dispersion interaction.