温度对MOF-74(Ni)吸附分离丙烯丙烷机理和选择性的影响

doi:10.11949/j.issn.0438-1157.20151519

摘要/Abstract

摘要：

采用水热法成功制备了MOF-74(Ni),使用PXRD、孔径分析对材料进行了表征,测定了材料在不同温度下的C₃H₆和C₃H₈吸附等温线,应用程序升温脱附技术估算了脱附活化能,并使用IAST理论预测了材料对C₃H₆/C₃H₈二元体系的吸附选择性。讨论了温度对吸附机理和吸附选择性的影响。结果显示,MOF-74(Ni)的BET比表面积高达1306 m²·g^-1。在298 K下,C₃H₆的吸附量高达7.4 mmol·g^-1。随着温度升高,C₃H₈的吸附量大幅降低,而C₃H₆的吸附量下降程度较小,导致材料对C₃H₆/C₃H₈吸附选择性升高。当温度为328K时,MOF-74(Ni)对C₃H₆/C₃H₈二元气体混合物的吸附选择接近12。程序升温脱附的实验结果显示,C₃H₆在MOF-74(Ni)上的脱附活化能大于C₃H₈,分别为68.92 kJ·mol^-1和50.80 kJ·mol^-1。C₃H₆是通过与MOF-74(Ni)的不饱和金属位点Ni²⁺以p络合作用方式吸附,作用力较强,而C₃H₈与Ni²⁺之间的作用力较弱。根据吸附机理不同的特点,适当提高温度,将有助于提高MOF-74(Ni)吸附分离C₃H₆/C₃H₈混合物体系的吸附选择性。

关键词: MOF-74(Ni), 丙烯, 丙烷, 吸附等温线, 吸附选择性, 温度

Abstract:

MOF-74(Ni) was synthesized by solvothermal synthesis method and then characterized by PXRD and pore size analysis. Isotherms of C₃H₆ and C₃H₈ on the synthesized MOF-74(Ni) were measured at different temperatures. The temperature programmed desorption experiments were conducted to estimate the desorption activation energies of C₃H₆ and C₃H₈ on the MOF-74(Ni). IAST theory was applied to predict the adsorption selectivity of C₃H₆/C₃H₈ mixture. The effects of temperature on adsorption mechanism and adsorption selectivity were also discussed. Results showed that the as-synthesized MOF-74(Ni) had BET surfaces of 1306 m²·g^-1, and its C₃H₆ adsorption capacity was up to 7.4 mmol·g^-1 at 298 K. With rising temperature, the adsorption capacity of C₃H₈ on MIL-74(Ni) decreased sharply, while that of C₃H₆ decreased slightly, resulting in improvement of C₃H₆/C₃H₈ adsorption selectivity of MOF-74(Ni). It could be attributed to p-complexation bonding between C₃H₆ and MOF-74(Ni), which was stronger than the interaction of C₃H₈ with MOF-74(Ni). TPD results indicated that the desorption activation energy of C₃H₆ on MOF-74(Ni) was higher than that of C₃H₈, which were 68.92 kJ·mol^-1 and 50.80 kJ·mol^-1, respectively.

Key words: MOF-74(Ni), propylene, propane, adsorption isotherms, adsorption selectivity, temperature

中图分类号:

TQ028.1
TB34

刘江, 吴玉芳, 许峰, 肖静, 夏启斌, 李忠. 温度对MOF-74(Ni)吸附分离丙烯丙烷机理和选择性的影响[J]. 化工学报, 2016, 67(5): 1942-1948.

LIU Jiang, WU Yufang, XU Feng, XIAO Jing, XIA Qibin, LI Zhong. Effects of temperature on adsorption mechanism and adsorption selectivity of C₃H₆ and C₃H₈ on MOF-74(Ni)[J]. CIESC Journal, 2016, 67(5): 1942-1948.

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