Abstract:

HP?MOF?74(Mg _x Ni_1-x ) (x=0.25, 0.50, 0.75) was synthesized by solvothermal method with Mg and Ni as central metals and sodium dodecylbenzene sulfonate (SDBS) as template. Using flue gas CO₂ and N₂ as adsorbents, the performance of HP?MOF?74(Mg _x Ni_1-x ) in adsorption and separation of CO₂/N₂ at 273 K and 298 K was investigated, the isotherms of CO₂ and N₂ on three different HP?MOF?74(Mg _x Ni_1-x ) materials were measured at 273 K and 298 K by static volumetric method, and the experimental data sets were fitted by Dual Site Langmuir Freundlich (DSLF) and Single Site Langmuir Freundlich (SSLF) models. The adsorption selectivity of CO₂/N₂ binary mixture was estimated according to the Ideal Adsorption Solution Theory (IAST). In addition, the isosteric heat of adsorption (Q_st) was calculated using the Clausius Clapeyron equation. The results show that the CO₂ adsorption capacity of HP?MOF?74(Mg_0.50Ni_0.50) sample is 4.864 mmol/g at 273 K and 100 kPa; the adsorption isotherms of CO₂ and N₂ on HP?MOF?74(Mg _x Ni_1-x ) are in good agreement with Dual Site Langmuir Freundlich (DSLF) and Single Site Langmuir Freundlich (SSLF) models respectively, indicating that the adsorption behavior of CO₂ is double sites adsorption, while the adsorption behavior of N₂ is single site adsorption; at 273 K and 100 kPa, the IAST adsorption selectivity of HP?MOF?74(Mg_0.25Ni_0.75) for CO₂ is 2 263, and the adsorption capacity and selectivity are better than those of traditional adsorbent MOF?74; the CO₂ isosteric heat of adsorption on HP?MOF?74(Mg _x Ni_1-x ) is higher than that of N₂, indicating that the surface free binding energy of CO₂ on HP?MOF?74(Mg _x Ni_1-x ) is higher.

Key words: HP?MOF?74(Mg _x Ni_1-x ), CO₂/N₂ adsorption separation, Adsorption isotherm, Henry selectivity, Flue gas

摘要：

以Mg、Ni为中心金属、十二烷基苯磺酸钠（SDBS）为模板剂，采用溶剂热法合成HP?MOF?74（Mg _x Ni_1-x ）（x=0.25、0.50、0.75）样品，以烟道气中CO₂和N₂为吸附质，考察了HP?MOF?74（Mg _x Ni_1-x ）样品在273 K和298 K下吸附分离CO₂/N₂的性能；通过静态容量法在273 K和298 K处测试了三种不同HP?MOF?74（Mg _x Ni_1-x ）样品上CO₂和N₂的等温线，并使用双位点Langmuir?Freundlich（DSLF）和单位点Langmuir?Freundlich（SSLF）模型对获得的实验数据集进行了拟合；根据理想吸附溶液理论（IAST），估算了CO₂/N₂二元混合物的吸附选择性；使用Clausius–Clapeyron方程计算了等量吸附热（Q_st）。结果表明，在273 K和100 kPa的条件下，HP?MOF?74(Mg_0.50Ni_0.50)样品的CO₂吸附量为4.864 mmol/g；CO₂和N₂在HP?MOF?74(Mg_0.50Ni_0.50)样品上的吸附等温线分别与DSLF和SSLF模型十分吻合，说明CO₂的吸附行为是双孔位吸附，而N₂的吸附行为是单位点吸附；HP?MOF?74（Mg_0.25Ni_0.75）样品对CO₂的IAST吸附选择性为2 263，吸附量和选择性均优于传统吸附剂MOF?74材料；CO₂在HP?MOF?74（Mg _x Ni_1-x ）样品上的等量吸附热均高于N₂，说明CO₂在HP?MOF?74（Mg _x Ni_1-x ）样品上的表面自由结合能更高。

关键词: HP?MOF?74(Mg _x Ni_1-x ), CO₂/N₂吸附分离, 吸附等温线, Henry选择性, 烟道气