Controlled Fabrication And Gas Separation Performance Of Ordered Microporous Carbon Membranes

Carbon membranes（CMs）are a new type of excellent porous inorganic membranematerial, taking the advagtages of outstanding gas separation performance, thermal stabilityand anti-corrosion, etc. CMs are commonly prepared by the pyrolysis of organic membrane athigh temperature. CMs can be used in various fields, such as oxygen enrichment, hydrogenrecovery, and acid gas removal from natural natural gas, and so on. The development oftraditional CMs has been restricted by the limitation of their tradeoff relationship betweenpermeability and selectivity, as well as the high fabrication-cost and fragility. In the pasttwenty years, results have shown that it is necessary to optimize the micropore structure so asto improve the separation performance substantially. Recently, a new type of ordered porestructure carbon membranes have gained much attention for it can be used to developfunctionalization, modeling, and gas separation. According to the theoretical analysis it willget ultra-high permeability and distinguishment ability if the accurate control of ordered porestructure carbon membranes were achieved. Unfortunately, rare report can be found on thepreparation of ordered porous carbon membranes (OPCM) with molecular sieve ability.In this thesis, OPCM was prepared by using self-made phenolic resin (PR) as precursor,block copolymer P123and F127as template, via the processes of organic-organicself-assembly and pyrolysis. In addition,another kind of OPCM was also fabriated by adoptingpolyimide as carbon source, mesoporous materials SBA-15as hard template, through thehybridization, membrane-forming, pyrolysis and etching. In addition, supported carbonmemrbanes were also formed by the abovementioned two kinds of carbon membranes bycoating technique. A large variety of advanced techniques were used to character the thermalstability of precursor, evolution of functional groups, morphology, pore structure, carbonstructure and gas separation performance of the samples, including thermogravimetry, Fouriertransformed infrared spectroscopy, scanning electron microscopy, transmission electronmicroscopy, X-ray diffraction, nitrogen adsorption and permeation, etc. The contents of thetemplate, pyrolysis temperature, the time of solvent evaporation and the etching conditions,etc., were also investigated on the thermal stability, carbon structure, pore structure and gasseparation performance. The results have showed that:(1) PR is a kind of ideal precursor candidate to prepareCMs, which can effectively control the rate of synthesis of PR for its few reactive sites. Theprocess of organic-organic self-assembly is beneficial to the production of ordered porousstructure between PR resin and PEO-PPO-PEO triblock copolymer.(2) The microporestructure and gas separation of OPCM are highly susceptible to the contents of P123, solventevaporation time and membrane-form substrate due to it is difficult to control themembrane-form performance. The gas permeability reach to40342.96Barrer(1Barrer＝1×10-10cm3(STP)cm/cm2s cmHg),51857.11Barrer,60316.96Barrer and8285.88Barrercorrespondingly for H2, CO2, O2and N2when the mole ratio of P123and the time of solventevaporation are0.012and6h, respectively, and pyrolysis at600℃, along with the selectivityof4.87(H2/N2),6.25(CO2/N2),7.28(O2/N2).(3) It indicates that the more content of F127, thelarger pore size, volume and surface for carbon membranes, the optimum mole ratio of F127is0.01in the course of preparating of OPCM with F127as template.(4) Microporous atmolecular level can be formed during the preparation of polyimide based OPCM with SBA-15as hard template. In the case of SBA-15doped precuesor membrane, high content tends togenerate precursor with high thermal stability and the better gas permeability of CMs, at theloss of selectivity due to SBA-15aggregation. The gas permeability of CMs without SBA-15reaches to874.37Barrer,687.15Barrer,143.94Barrer and63.04Barrer correspondingly forH2, CO2, O2and N2, along with the selectivity of13.87(H2/N2),10.90(CO2/N2),2.28(O2/N2).The gas permeability of the hybrid carbon membranes reach to23163.78Barrer,197.42Barrer,271.35Barrer and62.04Barrer correspondingly for H2, CO2, O2and N2, along with theselectivity of373.37(H2/N2),3.18(CO2/N2),4.37(O2/N2) when the amount of SBA-15is1%.(5) The number of coating times effect the microstructure and the finally gas separationperformance in the process of the preparation of the supportted carbon membranes. Finally theoptimization is4times. The supportted CMs made by coating4times possess2.94times,1.63times,2.58times higher in permeability magnitude for H2, CO2and O2and3.99times,2.19times,3.52times higher in selectivity magnitude for H2/N2, CO2/N2, O2/N2than those of CMsby6times.