Department of Chemical Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.
Dalton Trans. 2019 Apr 2;48(14):4685-4695. doi: 10.1039/c9dt00222g.
In this article, zeolitic-imidazolate framework-8 (ZIF-8) and its mixed metal CoZn-ZIF-8 were synthesized via a rapid microwave method. The products were characterized by Raman spectroscopy, XPS, XRD, EDX, TEM, NanoSEM, TGA, and DSC. The gas adsorption properties of samples were determined using C3 and C4 hydrocarbons, including propane, propylene, isobutane and n-butane at a temperature of 25 °C. The adsorption equilibrium and kinetics of these gases on various ZIFs were studied. It was noted that ZIF-8 and mixed metal CoZn-ZIF-8 samples start to adsorb these gases after certain pressures which are believed to result in the opening of their nano-gates (i.e., 6-membered rings) to allow the entry of gas molecules. The nanogate opening pressure value (p0) for each ZIF towards different gases was determined by fitting adsorption equilibrium data against a modified form of the Langmuir adsorption isotherm model. It was observed that the value of p0 differs significantly for each gas and to various extents for various ZIFs. Therefore, it is possible that the distinct values of p0 afford a unique technique to separate and purify these gases at the industrial scale. The overall mass transfer coefficient values of the adsorption process were also investigated.
在本文中，通过快速微波法合成了沸石咪唑酯骨架-8（ZIF-8）及其混合金属 CoZn-ZIF-8。通过拉曼光谱、XPS、XRD、EDX、TEM、NanoSEM、TGA 和 DSC 对产物进行了表征。在 25°C 的温度下，使用包括丙烷、丙烯、异丁烷和正丁烷在内的 C3 和 C4 烃类来测定样品的气体吸附性能。研究了这些气体在各种 ZIF 上的吸附平衡和动力学。结果表明，ZIF-8 和混合金属 CoZn-ZIF-8 样品在一定压力下开始吸附这些气体，据信这导致其纳米门（即六元环）打开，允许气体分子进入。通过将吸附平衡数据拟合到改进的 Langmuir 吸附等温线模型，确定了每个 ZIF 对不同气体的纳米门开启压力值（p0）。结果表明，p0 值因气体而异，且对不同的 ZIF 也有显著差异。因此，p0 的独特值有可能为这些气体在工业规模上的分离和纯化提供一种独特的技术。还研究了吸附过程的整体传质系数值。
