SBA-15介孔分子筛在烯烃/烷烃分离中的应用

Application of SBA-15 Mesoporous Molecular Sieve to Separation of Olefin/Paraffin Mixtures

采用一步法合成了SBA-15介孔分子筛,并利用气相色谱技术考察了它作为色谱固定相对气态烯烃/烷烃混合物和液态烯烃/烷烃混合物的分离性能。实验结果表明,SBA-15介孔分子筛作为色谱固定相能在较短的时间内实现对含有甲烷、乙烷、乙烯、丙烷和丙烯的气态烃类混合物的分离,也能分离正己烷/1-己烯、正庚烷/1-庚烯、正辛烷/1-辛烯3种液态烃类混合物。采用XRD、N_2吸附-脱附等手段对SBA-15介孔分子筛进行了表征,表征结果显示,合成的SBA-15介孔分子筛具有较大的比表面积和孔体积,孔分布较窄,结构中含有一定数量的微孔。由于其主介孔壁上存在微孔,构成吸附位,对烯烃分子表现出更高的选择性,且其织构性能优良,因此与常规色谱填料硅胶相比,SBA-15介孔分子筛更适合作为烯烃/烷烃分离的色谱固定相。

SBA-15 mesoporous molecular sieve self-prepared through one-step synthesis was used in separation of olefin/paraffin mixtures by means of gas chromatographic technique. Separation of the gaseous mixture of methane, ethane, ethylene, propane and propylene could be achieved in short retention time by using the SBA-15 mesoporous molecular sieve as chromatographic stationary phase. The SBA-15 mesoporous molecular sieve could be applied to separation of liquid mixtures of n-hexane/1-hexene, n-heptane/1-heptene and n-octane/1-octene also. Structure of the SBA-15 mesoporous molecular sieve was characterized by means of XRD and N2 adsorption-desorption. The synthesized SBA-15 mesoporous molecular sieve possessed large specific surface area and pore volume, narrow pore size distribution and some micropores. Due to its excellent textural properties and high adsorption selectivity to olefins, which should be attributed to the micropores as adsorption sites existing on the mesopore wall, SBA-15 mesoporous molecular sieve was more suitable as the stationary phase for gas chromatographic separation of olefin/paraffin than conventional silica gel.