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

Abstract

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 °C for 1 h in air (heating rate: 0.5 °C/min) and then carbonized at 800 °C (heating rate: 0.5 °C/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.