High performance compatible thiazole-based polymeric blend cellulose acetate membrane as selective CO2 absorbent and molecular sieve

Green blend membranes comprise of high thermal resistance ortho-linked thiazole-based polyimine (PM-4) including thioether linkage were fabricated in combination of glassy cellulose acetate (CA). The thermal stabilities of PMs were examined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphological aspects and functional groups of the membranes were investigated via field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR-ATR) analysis respectively. X-ray diffraction (XRD) and mechanical strength were determined as well. The effects of polyimine content, pressure and temperature were studied on CO2 permeability (P) and selectivity. The pressure changes revealed exponentially increases on CO2 permeability by plasticization, facilitated transfer and solution-diffusion mechanisms, but decreases on CH4 and N2 permeations. Remarkable permeation (P = 3000 Barrer) of CA/PM-4 (1:3 % w/w) and ideal selectivity ratios of CO2/N2 = 59, CO2/CH4 = 33.7 were obtained at 3 bar and 35 ◦C versus neat CA membrane.本研究制备了含硫醚键的高热稳定性邻位连接噻唑基聚亚胺（PM-4），并将其与玻璃态醋酸纤维素（cellulose acetate, CA）共混，制得绿色共混膜。采用热重分析（thermogravimetric analysis, TGA）与差示扫描量热法（differential scanning calorimetry, DSC）对聚亚胺（PM）的热稳定性进行了表征；分别通过场发射扫描电子显微镜（field emission scanning electron microscopy, FESEM）与傅里叶变换红外光谱-衰减全反射（Fourier transform infrared spectroscopy–attenuated total reflectance, FTIR-ATR）分析，表征了该共混膜的形貌特征与官能团结构；同时还测定了该膜的X射线衍射（X-ray diffraction, XRD）图谱与机械强度。本研究考察了聚亚胺含量、操作压力与温度对CO₂渗透系数（P）与分离选择性的影响。结果显示，压力变化会通过塑化作用、促进传递及溶液扩散机制使CO₂渗透系数呈指数级提升，但会降低CH₄与N₂的渗透性能。在3 bar、35 ℃条件下，相较于纯CA膜，CA/PM-4（质量比1:3，weight/weight, w/w）膜展现出优异的CO₂渗透性能（P=3000 巴雷尔，Barrer），其CO₂/N₂理想选择性为59、CO₂/CH₄理想选择性为33.7。