Preparation And Performance Of Composite Carbon Membranes With Ordered Mesoporous Interlayer

Carbon membranes are a new type of membrane materials featuring with molecular sieving property, which can be potentially used in different gas separation, purification and membrane reactors, owing to many advantages that compared with polymers membranes, such as high gas separability, superior chemical and thermal stability and excellent capacity to endure high temperature and pressure, also modification of their surfaces and porous structure via physical or chemical methods to meet different need. However, the low mechanical strength has limited their wide utilization in gas separation. Composite carbon membranes can be prepared by coating precursor on supports to improve mechanical strength effectively, but if we desire to prepare composite carbon membranes without flaw, we should use the supports that have small pore diameter and smooth surface, and the consecutive and flawless separation can be prepared by coating repeatedly on the supports of big pore diamete. which will not only increase the difficulties of preparing composite carbon membranes, but decrease the permeability of carbon membranes. Thus, it remains a challenge to achieve industrialization and fabricate composite carbon membrane with high permeability and perfect selectivity.In order to avoid the flaw on the surface of support transfering to separation layer and reduce the coating times to improve the permeation of composite carbon membrane, we fabricated interlayer with ordered mesoporous carbon synthesizing by soft templating method on coal-based platy supports. The ordered mesoporous interlayer was prepared after carbonization, which modified the surface of supports and enhanced the gas permeation flux of carbon membrane.And then, a composite carbon membrane with separation layer was prepared by coating the precursors of Polyamic acid (PAA) on the interlayer and pyrolyzed to obtain the CCMs. We discuss the effect of support property, spin coating technology, etc on the gas separation performances of separation layer. And employ various Characterization method to demonstrate the apparent morphology and microstructure of the composite carbon membranes. The results indicate that the composite carbon membranes with high permeability and high selectivity can be prepared by coating one interlayer on coal-based platy supports. For the bituminous coal-based composite carbon membranes, the selectivities of H2/N2, CO2/N2, O2/N2 are 88.9, 16.5,11.3, respectively, and the O2 permeation rate of 7.00×10-9 mol·m·-2·s-1-Pa-1.