Diffusion mechanism of CO2 in 13X zeolite beads
Diffusion mechanism of CO2 in 13X zeolite beads
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DOI：
10.1007/s10450-013-9554-z
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发表时间：
2014-01-01
影响因子：
3.3
通讯作者：
Brandani, Stefano
中科院分区：
文献类型：
--
作者：
Hu, Xiayi;Mangano, Enzo;Brandani, Stefano
本文系统地研究了工业13X沸石小球中CO2的扩散机理。为了全面了解CO2的扩散过程，用零长度色谱柱(ZLC)系统和容积仪进行了动力学测量。ZLC实验是在13X沸石的单个珠子上进行的，温度为38摄氏度，二氧化碳分压为0.1bar，代表燃烧后捕获的条件。用不同载气进行的实验清楚地表明，扩散过程受控于大孔内的传输。使用Quantachrome Autosorb系统在不同浓度下进行了体积测量。这些实验是在没有载气的情况下进行的，低压测量清楚地显示了吸收池和微珠大孔中的努森扩散控制。随着CO2浓度的增加，迁移机制从大孔内的努森扩散转变为完全热限制的过程。这两组实验都与珠孔含气率和曲折度的独立测量结果一致，并确认在碳捕获过程的典型条件范围内，系统受大孔扩散机制控制。
A systematic study of the diffusion mechanism of CO2 in commercial 13X zeolite beads is presented. In order to gain a complete understanding of the diffusion process of CO2, kinetic measurements with a zero length column (ZLC) system and a volumetric apparatus have been carried out. The ZLC experiments were carried out on a single bead of zeolite 13X at 38 A degrees C at a partial pressure of CO2 of 0.1 bar, conditions representative of post-combustion capture. Experiments with different carrier gases clearly show that the diffusion process is controlled by the transport inside the macropores. Volumetric measurements using a Quantachrome Autosorb system were carried out at different concentrations. These experiments are without a carrier gas and the low pressure measurements show clearly Knudsen diffusion control in both the uptake cell and the bead macropores. At increasing CO2 concentrations the transport mechanism shifts from Knudsen diffusion in the macropores to a completely heat limited process. Both sets of experiments are consistent with independent measurements of bead void fraction and tortuosity and confirm that under the range of conditions that are typical of a carbon capture process the system is controlled by macropore diffusion mechanisms.