The Preparation Of Process Optimization For Coal-based Tubular Carbon Membranes

Carbon membranes which are usually prepared by carbonizing carbonaceous materials can be applied in many fields due to their thermal and chemical stability, good conductivity and mechanical strength. In the preparation of carbon membranes, some expensive supports such as ceramic membrane are used and restricted the application of carbon membrane on commercial scale. Coal is a cheap precursor for the preparation of carbon membranes owing to its low cost and aromatic structure, which will significantly be to reduce the cost and improve the competitiveness of carbon membrane in its commercial application. Our group has developed a technology to prepare the coal-based tubular carbon membrane in past ten years. However, there are still some problems existed, such as the pinhole, low strength and wide pore structure in carbon membranes. They need to be further optimized for their commercial application.To solve the above key problems, the preparation processes are optimized to improve the wetting, dispersing and plasticing of mud for eliminating surface defects of carbon membrane by adding surfactants and modifying agents and to improve the strength of carbon membranes by blending with different coals and adding the high residual binder and to control and regulate the pore structure by particle size of coal and pore-forming agent. Besides, the TG, XRD, SEM and Bubble-pressure method were employed to characterize structure and properties of carbon membranes. The results show that adding wetting and dispersing agent can greatly reduce the defects of carbon membranes and improve the pore size distribution and porosity. The maximum compressive strength of carbon membrane is 190.7N/m when the addition ratios of gas, coking and lean coal are 30%,40%,30% respectively. Addition of coal tar can increase the compressive strength by nearly four times and improve the composition of carbon fiber and carbon matrix. The pore structure of carbon membrane can be controlled by regulating coal particle distribution and pore-forming agent.