A high-permeance supported carbon molecular sieve membrane fabricated by plasma-enhanced chemical vapor deposition followed by carbonization for CO2 capture

We proposed a novel method of combining plasma-enhanced chemical vapor deposition and carbonization to fabricate supported carbon molecular sieve (CMS) membranes. It proved to be more efficient than the traditional technique of repeated cycles of spin-coating and carbonization. The effect of carbonization temperature on the membrane physical morphology, chemical structure, and separation performance was investigated. Results showed that the carbonized membranes were defect-free, as characterized by both scanning electron microscopy and positron annihilation lifetime spectroscopy, despite the reduced membrane selective layer thickness at high carbonization temperatures. Raman and X-ray photoelectron spectroscopy demonstrated that the CMS membranes carbonized at high temperatures consisted of a graphite-like structure. As such, their gas separation performance was enhanced compared with the precursor membrane, particularly the permeance. The supported CMS membrane obtained at a carbonization temperature of 500 °C gave the following gas separation performance: CO2 permeance=772.1 GPU, CO2/N2 selectivity=14.3; O2 permeance=150.6 GPU, and O2/N2 selectivity=2.8.