Hao Xiaofei, Li Zhen, Hu Hongjie, Liu Xueqin, Huang Yanqiu
Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan, China.
Zhengzhou Fulong Science and Technology of New Materials Co., Ltd., Zhengzhou Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Zhengzhou, China.
Front Chem. 2018 Dec 18;6:633. doi: 10.3389/fchem.2018.00633. eCollection 2018.
Clinoptilolite is a widely distributed tectosilicate, mainly composed of AlO, SiO with exchangeable cations such as Ca, K, Mg, and Na. In this research, raw clinoptilolite was ground, gravimetrically concentrated and ion-exchanged using different concentrations of NaCl solution. Then the modified clinoptilolite powder was formulated into particles as adsorbents. The adsorbents were applied to CH separation in coal bed gas. The raw and modified clinoptilolites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), atomic emission spectrometer (ICP-AES), Fourier transform infrared spectrometer (FTIR), and Brunauer Emmett Teller (BET) specific surface area. The CH absorptivity by raw and modified clinoptilolites was evaluated using pressure swing adsorption (PSA) to assess the CH separation ability. The results indicated that the ion-exchanged clinoptilolite using 0.2 mol/L NaCl solution was found to be promising for the kinetic PSA separation of CH/N, giving a better absorptivity for CH separation under different influence factors. Based on the simulated static experiments, it was indicated that both CH and N were capable of diffusing into clinoptilolite while N adsorption by clinoptilolite was excellent. The experiment results also indicated that ion-exchanged clinoptilolite using a 0.2 mol/L NaCl solution was the optimal adsorbent for separating CH/N at the low pressure condition. From the simulated dynamic experiments, the ion-exchanged clinoptilolite using a 0.2 mol/L NaCl solution as a potential sorbent in kinetic PSA processes for N/CH separation, exhibited the best performance at 648 K under 0.2 MPa within 28 min, in comparison to the raw clinoptilolite and clinoptilolite under other modification conditions. In the next phase of research, the modified clinoptilolite will be tested for CH separation in real coal bed gas.
斜发沸石是一种分布广泛的构造硅酸盐，主要由AlO、SiO以及Ca、K、Mg和Na等可交换阳离子组成。在本研究中，将天然斜发沸石研磨、进行重量法富集，并使用不同浓度的NaCl溶液进行离子交换。然后将改性斜发沸石粉末制成颗粒作为吸附剂。这些吸附剂应用于煤层气中CH的分离。通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、原子发射光谱仪（ICP - AES）、傅里叶变换红外光谱仪（FTIR）和布鲁诺尔-埃米特-泰勒（BET）比表面积对天然和改性斜发沸石进行了表征。使用变压吸附（PSA）评估天然和改性斜发沸石对CH的吸附率，以评估CH的分离能力。结果表明，使用0.2 mol/L NaCl溶液进行离子交换的斜发沸石在CH/N的变压吸附动力学分离方面具有潜力，在不同影响因素下对CH分离具有更好的吸附率。基于模拟静态实验表明，CH和N都能够扩散到斜发沸石中，而斜发沸石对N的吸附效果良好。实验结果还表明，使用0.2 mol/L NaCl溶液进行离子交换的斜发沸石是低压条件下分离CH/N的最佳吸附剂。从模拟动态实验来看，使用0.2 mol/L NaCl溶液进行离子交换的斜发沸石作为N/CH分离变压吸附动力学过程中的潜在吸附剂，与天然斜发沸石和其他改性条件下的斜发沸石相比，在648 K、0.2 MPa条件下28分钟内表现出最佳性能。在研究的下一阶段，将对改性斜发沸石在实际煤层气中进行CH分离测试。
