| Carbon membranes are a new type of membrane materials featuring with molecular sieving property,which are mainly prepared by pyrolysis of polymers as precursors. Compared with polymeric membranes,carbon membranes have broad prospects in gas separation for possessing numerous advantages,such as high gas separation factor,good thermal resistance and chemical inertness.Carbon membranes can be divided into two categories:homogeneous and composite.The carbon composite membranes have attracted much attention recently because of their high mechanical strength.But the materials for the carbon membrane supports are usually high cost,which restricts the development and application of carbon composite membranes.Therefore,it is necessary to research and development low cost supports for the industrialization of carbon composite membranes.In this paper,coal based plate carbon membrane supports have been prepared by anthracite with blender and bituminous coal.The effect of processing parameters such as binder type,molding pressure,pre-oxidation temperature and pre-oxidation time on the performance of coal-based carbon membrane supports has been investigated,the technology route to prepare the coal-based carbon membrane supports has also been designed.The results show that the coal-based carbon membrane supports prepared with different metamorphic grade coals have different pore structure characteristics,the anthracite-based carbon membrane supports have a wide pore size distribution and a high gas permeation rate,but the largest pore diameter is larger,however,the bituminous coal-based carbon membrane supports have a narrow pore size distribution and the largest pore diameter is smaller.Hence the bituminous coal-based carbon membrane supports are more suitable to prepare carbon composite membranes.The plate carbon composite membranes have been prepared by spin-coating the PMDA-ODA polyamic acid(PAA)on the coal-based membrane supports.The effect of support property,spin coating technology,blending the surfactant in PAA and the pretreatment of the membrane support on the gas separation performances of carbon composite membranes has been investigated.Scanning electron microscope has also been employed to characterize the microstructure of the carbon composite membranes.The results indicate that the carbon composite membranes with high performances can be prepared by controlling spin coating technology.The surfactant showed the function of improving the composite between carbon plate and PAA,Carbon composite membranes with the suffactant additive reaching molecular sieving need only one time by spin-coating.The pre-immersing treatment on anthracite supports can greatly improve the gas permeation rate of the anthracite-based carbon composite membranes.For the bituminous coal-based carbon composite membranes,the selectivities of H2/N2,CO2/N2,O2/N2 are 94.3,18.3,10.2 respectively,and the selectivity for O2/N2 of air is 10.8 with the O2 permeation rate of 4.99×10-9mol·m·-2·S-1.Pa-1and the O2 concentration can reach 74.4%by one time enrichment. |
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