Preparation of supported carbon molecular sieve membrane from novolac phenol-formaldehyde resin

摘要

An asymmetric carbon membrane was prepared by coating alcohol solution of novolac phenol-formaldehyde resin containing a little hexamine on a porous resin support from the same material. After drying in air for two days at room temperature, the coated support was heated at 150℃rnfor 1 h in air (heating rate: 0.5℃/min) and then carbonized at 800℃ (heating rate: 0.5℃/min) in Ar atmosphere. The support and the membrane layer were carbonized simultaneously. The coating-pyrolysis cycle only needed one time. SEM photographs showed the carbon membrane had an asymmetric structure formed by a dense skin layer with a thickness of around 35 μm and a porous substrate. Pure gases of different molecular size (H_2, CO_2, O_2, N_2 and CH_4) were used to test the carbon membrane permeance property. The membrane has a good selectivity for H_2/N_2 and H_2/CH_4 with H_2 permeance of 4.05 × 10~(-6) cm~3 cm~(-2) s~(-1) cmHg~(-1). The permeance is independent of pressure. The results indicate that the gases transport through the membrane according to molecular sieve mechanism.