Characterization of Micro- and Mesoporous Materials Using Accelerated Dynamics Adsorption

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• 作者：Ali Qajar ; Maryam Peer ; Ramakrishnan Rajagopalan ; Henry C. Foley
• 刊名：Langmuir
• 出版年：2013
• 出版时间：October 8, 2013
• 年：2013
• 卷：29
• 期：40
• 页码：12400-12409
• 全文大小：484K
• 年卷期：v.29,no.40(October 8, 2013)
• ISSN：1520-5827

文摘

Porosimetry is a fundamental characterization technique used in development of new porous materials for catalysis, membrane separation, and adsorptive gas storage. Conventional methods like nitrogen and argon adsorption at cryogenic temperatures suffer from slow adsorption dynamics especially for microporous materials. In addition, CO₂, the other common probe, is only useful for micropore characterization unless being compressed to exceedingly high pressures to cover all required adsorption pressures. Here, we investigated the effect of adsorption temperature, pressure, and type of probe molecule on the adsorption dynamics. Methyl chloride (MeCl) was used as the probe molecule, and measurements were conducted near room temperature under nonisothermal condition and subatmospheric pressure. A pressure control algorithm was proposed to accelerate adsorption dynamics by manipulating the chemical potential of the gas. Collected adsorption data are transformed into pore size distribution profiles using the Horvath鈥揔avazoe (HK), Saito鈥揊oley (SF), and modified Kelvin methods revised for MeCl. Our study shows that the proposed algorithm significantly speeds up the rate of data collection without compromising the accuracy of the measurements. On average, the adsorption rates on carbonaceous and aluminosilicate samples were accelerated by at least a factor of 4鈥?.