Thermodynamics of hydrogen adsorption on calcium-exchanged faujasite-type zeolites
Thermodynamics of hydrogen adsorption on calcium-exchanged faujasite-type zeolites
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DOI：
10.1016/j.ijhydene.2009.03.031
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发表时间：
2009-05
影响因子：
7.2
通讯作者：
G. Palomino;B. Bonelli;C. Areán;J. Parra;M. Carayol;M. Armandi;C. Ania;E. Garrone
中科院分区：
文献类型：
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作者：
G. Palomino;B. Bonelli;C. Areán;J. Parra;M. Carayol;M. Armandi;C. Ania;E. Garrone
采用可变温度红外光谱和体积气体吸附测量相结合的方法研究了低温下钙交换沸石X和y上氢吸附的热力学。考虑了两种吸附机制：(i)二氢分子在Ca2+阳离子位点上的局部吸附，以及（ii） Ca2+吸附中心饱和后的离域氢吸附。局域吸附的焓变在−12 ~−15kJmol−1之间，局域吸附的等容热在4.5 ~ 5.5 kjmol−1之间。这些实验结果在更广泛的背景下讨论了其他碱性沸石的相应数据，重点讨论了局部吸附机制的吸附焓和熵之间的相关性。
A combination of variable-temperature infrared spectroscopy with volumetric gas adsorption measurements was used to study the thermodynamics of hydrogen adsorption, at a low temperature, on calcium-exchanged zeolites X and Y. Two adsorption regimes were considered: (i) localized adsorption of dihydrogen molecules on Ca2+cation sites, and (ii) delocalized hydrogen adsorption following saturation of the Ca2+adsorbing centres. For localized adsorption, the corresponding enthalpy change was found to be in the range of −12 to −15kJmol−1, while the isosteric heat of delocalized adsorption was found to be in the range of 4.5–5.5kJmol−1. These experimental results are discussed in the broader context of corresponding data for other alkaline zeolites, with a focus on correlation between adsorption enthalpy and entropy for the localized adsorption regime.