Preparation of microfiltration carbon membrane by pyrolysis of phenol-formaldehyde resin

The microfiltration carbon membrane was prepared by pyrolysis of novolac phenol-formaldehyde resin. The effects of carbonization conditions, including carbonization temperature, heating rate, holding time and protective gas flow rate, and activation conditions on the carbon membrane properties were systematically investigated. The mass loss during carbonization was characterized by thermogravimetric analysis. The gas bubble pressure method was used to determine the pore size distribution of the carbon membrane. The results indicate that the gas permeation rate and the mean pore size of carbon membrane decrease with the increase of carbonization temperature. The gas permeation rate decreases from 1.84 × 10-5 mol/(m2·s·Pa) to 1.14 × 10-5 mol/(m2·s·Pa) and the mean pore size decreases from 0.61 μm to 0.54 μm with the carbonization temperature from 650°C to 950°C. The carbon membrane carbonized at 350°C shows the lowest strength. Above 350°C, high carbonization temperature results in high strength carbon membrane. The heating rate, holding time and protective gas flow rate have little effect on the carbon membrane properties. Activation of carbon membrane with CO2 increases the pore size of membrane. With CO2 content increasing from 12.5% to 50%, the gas permeation rate increases from 7.0 × 10-5 mol/(m2·s·Pa)to 1.68 × 10-4 mol/(m2·s·Pa) and the mean pore size increases from 1.54 μm to 1.96 μm.