温度对MOF-74(Ni)吸附分离丙烯丙烷机理和选择性的影响  

Effects of temperature on adsorption mechanism and adsorption selectivity of C_3H_6 and C_3H_8 on MOF-74(Ni)

作　　者：刘江[1] 吴玉芳[1] 许峰[1] 肖静[1] 夏启斌[1] 李忠[1] 

机构地区：[1]华南理工大学化学与化工学院,广东广州510640

出　　处：《化工学报》2016年第5期1942-1948,共7页CIESC Journal

基　　金：国家自然科学基金重点项目(21436005)~~

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C_3H_6和C_3H_8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C_3H_6/C_3H_8二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,C_3H_6的吸附量高达7.4 mmol·g^(-1)。随着温度升高,C_3H_8的吸附量大幅降低,而C_3H_6的吸附量下降程度较小,导致材料对C_3H_6/C_3H_8吸附选择性升高。当温度为328K时,MOF-74(Ni)对C_3H_6/C_3H_8二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,C_3H_6在MOF-74(Ni)上的脱附活化能大于C_3H_8,分别为68.92 k J·mol^(-1)和50.80 k J·mol^(-1)。C_3H_6是通过与MOF-74(Ni)的不饱和金属位点Ni2+以π络合作用方式吸附,作用力较强,而C_3H_8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C_3H_6/C_3H_8混合物体系的吸附选择性。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 m^2·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 π-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 k J·mol^-1 and 50.80 k J·mol^-1, respectively.

关 键 词：MOF-74(Ni) 丙烯 丙烷 吸附等温线 吸附选择性 温度 

分 类 号：TQ028.1[化学工程] TB34[一般工业技术—材料科学与工程]