聚糠醇炭分子筛膜的制备及O_2/N_2分离性能研究

以草酸为催化剂将糠醇单体直接聚合成所需黏度的聚糠醇液体作为涂膜液,仅需一步涂覆便可在价格低廉的煤基炭管支撑体上制备出高性能的聚糠醇炭分子筛膜.聚糠醇炭分子筛膜的热解过程、微观形貌和分离性能分别采用热重分析、扫描电镜以及O2、N2渗透实验进行表征.实验结果表明制备出的聚糠醇炭分子筛膜表面均匀且无缺陷.聚糠醇在热解过程中最终转化成具有超微孔的乱层石墨微晶结构.热解温度升高导致了起分离作用的有效超微孔尺寸的减小,进而表现出O2、N2的渗透速率逐渐降低,O2/N2的选择性逐渐增大的趋势.不同热解温度下制备的炭分子筛膜的O2渗透性和O2/N2选择性之间关系均超出了传统聚合物膜的Robeson上限.

PREPARATION AND O2/N2 SEPARATION PERFORMANCE OF CARBON MOLECULAR SIEVE MEMBRANES DERIVED FROM POLY(FURFURYL ALCOHOL)

A convenient and effective approach has been developed to prepare carbon molecular sieve (CMS) membranes derived from poly ( furfuryl alcohol) with high O2/N2 separation performance in this paper. The CMS membranes is formed by coating a thin layer of viscous poly ( furfuryl alcohol) liquid,which was synthesized by polymerization of furfuryl alcohol by oxalic acid catalyst,on a porous coal-based tubular support followed by controlled pyrolysis. TGA,XRD,SEM and gas permeation experiments are employed to give an insight into pyrolysis process,morphological characteristics and separation performance of CMS membranes. The results show that the CMS membranes with a continuous defect-free coating exhibit an excellent O2/N2 separation performance. The increase in the final pyrolysis temperature from 600℃ to 900℃ results in a decrease in the d-spacing of the interlayers of graphitic carbon planes and the shrinkage in size of ultramicropores,which leads to the reduction in permeabilities of O2 and N2 and improvement in O2/N2 permselectivity. It can also be found that the correlation points for all CMS membranes prepared in the present work fall above the Robeson's upper bound limit that is uncommon for polymeric membranes. These results indicate that poly ( furfuryl alcohol)-based CMS membranes obtained from the novel method are of great potential for O2 and N2 separation.