Preparation And Performance Of Composite Carbon Membranes With Micro-Mesoporous Structure

Membrane-based gas separation technology is a new and interdisciplinary separation technology, which has been widely investigated and used in various fields such as carbon dioxide recovery, acidic gas removal, oxygen/nitrogen separation in air, hydrogen recovery of the tail gas in ammonia synthesis, petrochemical industry and so on. Membrane-based gas separation technology is considered the most potential new gas separation technology, which is the fastest developing membrane separation technique in independent branch, and the characteristics is high-efficiency, economical, convenient and fast and undefiled. Carbon molecular sieving membrane (Carbon membrane), one of the membranes in the gas separation, is a novel inorganic membrane material with high selectivity, thermal stability and good chemical stability, also with the molecular sieve ability. And it has attached more attention owing to this.Carbon membranes can be divided into two categories:composite carbon membranes and homogeneous carbon membranes. The homogeneous carbon membrane is still commercially unavailable because of the texture brittle and it's researched mainly in the laboratory. However, the composite carbon membranes have attracted much attention in the near future because of their high mechanical strength provided from the supports. It is significative for the industrialized application. But, the materials for the carbon membrane supports are usually expensive such as porous stainless steel and ceramic substrate, which restricts the development and application of composite carbon membranes. In addition, the contradictions between permeability and selectivity restrict the development of Industrial application of composite carbon membranes. Hence, the composite carbon membrane with ordered mesoporous material can be manufactured, which shows acceleration effect for the industrial application.Herein, we fabricated ordered mesoporous carbon materials with dual templates. The ordered mesoporous polymer was lead in composite carbon membranes as interlayer, and the composite carbon membranes with high permeability and high selectivity can be prepared.Ordered mesoporous carbon materials were prepared by pyrolysis of polymers, which were formed by organic-organic self-assembly of resorcinol-formaldehyde composites and tri-block copolymers under acidic conditions. The tri-block copolymers F127 and P123 were employed as both structure-directing agents. The samples were characterized byâ…©-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen adsorption-desorption. The results show that ordered mesoporous carbons climb up and then decline as the holding time of synthesis extending from 24h to 72h. When the mole ratio of the main template to aided is 1:1, the mesoporous carbon obtained exhibits highly ordered hexagonal mesostructure Pm6m, with a typical BET surface area of 640.34m2/g, pore size of 3.68nm and pore volume of 0.59cm3/g.In this paper, low-cost coal-based platy supports were employed, and the polymers of mesoporous interlayer firstly coated on the supports. And then, a composite carbon membrane with mesoporous interlayer was prepared by coating the polyamic acid (PAA) on the interlayer and pyrolyzed to obtain the composite carbon membranes. We discuss the effect of structural behaviour of supports, spin coating technology, etc. on the gas permeation and separation performances of composite carbon membranes. The results show that the composite carbon membranes with high performance can be prepared in the best preparation process conditions.