SSZ-13分子筛选择性吸附分离CO2与CH4

Selective adsorption of CO2 and CH4 by SSZ-13 molecular sieves

以N,N,N-三甲基金刚烷基氢氧化铵(TMAdaOH)为模板剂,以水热合成法合成Na-SSZ-13分子筛。用硝酸铵、硝酸锂、硝酸钾对样品进行离子交换。通过XRD和FTIR和TGA对样品进行表征,采用吸附等温线和穿透曲线考察其对CO2/CH4吸附分离能力进行测试。吸附等温线结果表明,CO2在所有样品上的吸附量都优于CH4;CO2和CH 4的吸附量遵循Na-SSZ-13>Li-SSZ-13>H-SSZ-13>K-SSZ-13的顺序。穿透曲线结果表明,混合气体中,CH4首先穿透吸附床,CO2后穿出;穿透曲线吸附量及分离因子的结果与吸附等温线基本一致。K-SSZ-13的吸附量较低,但是具有极高的吸附选择性,是具有良好工业应用前景的吸附剂。

Na-SSZ-13 molecular sieves were synthesized by hydrothermal synthesis with N,N,N-trimethyl rigid alkyl ammonium hydroxide(TMAdaOH)as template.Ammonium nitrate,lithium nitrate and potassium nitrate were used for ion exchange.The samples were characterized by XRD,FT-IR and TGA,and the adsorption and separation ability of CO2/CH4 was tested by adsorption isotherms and penetration curves.The results of adsorption isotherms show that the adsorption capacity of CO2 on all samples is better than that of CH 4,because the electric field of the CH 4 molecule is weaker than that of CO2 and the molecule’s size is larger than it.The adsorption capacity of CO2 and CH 4 follows the order of Na-SSZ-13>Li-SSZ-13>H-SSZ-13>K-SSZ-13.The results of penetration curve show that CO2 is strong adsorbents and CH4 is weak adsorbents.Therefore,CH 4 first penetrate the adsorption bed and CO2 penetrate later.The results of adsorption capacity and separation factor of breakthrough curve are basically consistent with adsorption isotherms.Na-SSZ-13 has the highest adsorption capacity and selectivity because of the high electric field of Na+and the problem of occupying space in molecular sieves.K-SSZ-13 adsorption capacity is low,Na-SSZ-13 has very high adsorption selectivity and is an absorbent with good industrial application prospect.