Research On The PEK-C Based Supported Carbon Membrane Prepared By Spray Coating Method

The nanoporous carbon molecular sieve membrane is a novel membrane material. Compared with organic membrane, carbon membranes show great potential in gas separation field due to various significant potential advantages, such as high flux, high thermal resistance and chemical stability. The supported composite membranes with the necessary mechanical strength and high flux, good selectivity are beneficial to the commercial application of carbon membranes. The membranes prepared from cardo-polyaryl etther ketones (PEK-C) with main chain rigid and less stacking density have a high gas permeability. The spray-coating method is an outstanding technology of large-scale preparing carbon membrane, according to many advantages, such as precision control, good reproducibility, simple operation and easy to scale up.In this paper, PEK-C homogeneous membrane was prepared by coating method; then the primary property of the PEK-C membranes was tested. The supported composite membranes were prepared by spraying the PEK-C precursor on the supported carbon membranes. The influence factors of spraying process (parameters of atomization, the property of the supports, the content of PEK-C, the temperature of the heater roller, the feed mass per surface area) and the parameters of pre-oxidation and carbonization were systematically examined in this paper,which had a great effect on property of the composite membrane. The results indicated as followed.PEK-C exhibited excellent thermal stability. The thermal weight loss elevated at 440 ℃, and increased to 40% at 700 ℃. The molecular cross-linking happened in pre-oxidation period, and the proper temperature was 440℃.The chemical reaction speed was high and the membrane structure could be maintained in pre-oxidation at 440℃. The composite carbon membrane carbonized at 600℃ had high flux of O2 and N2, and the selectivity was also high.The spraying coating process and the thermal-treatment had great impacts on surface profile and the gas permeation. The adhesion between the separation layer and the supports was better when the casting solution spreaded quickly on the supported membrane. The separation layer was flatten with uniform thickness, when the supports had small pore size and narrow pore distribution and the PEK-C solution had suitable content, The cross-linking reaction rate increaseed with the pre-oxidation temperature, accompanied with high gas permeation of the membrane. The thermal decomposition rate and the gas permeation were both improved with the carbonization temperature increasing. The composite carbon membrane had a high O2 permeation rate of 173GPU,when pre-oxidatization and carbonization temperatures were 440℃ and 550℃, respectively, and the pre-oxidatization time was 60 min.