Carbon molecular sieve membranes for hydrogen purification from a steam methane reforming process

Asymmetric carbon molecular sieve (CMS) membranes prepared from cellulose hollow fiber precursors were investigated for H2/CO2 separation in this work. The prepared carbon membrane shows excellent separation performance with H2 permeance of 111 GPU and an H2/CO2 selectivity of 36.9 at 10 bar and 110 ?C dry mixed gas. This membrane demonstrates high stability under a humidified gas condition at 90 ?C and the pressure of up to 14 bar. A two-stage carbon membrane system was evaluated to be techno-economically feasible to produce high-purity H2 (>99.5 vol%) by HYSYS simulation, and the minimum specific H2 purification cost of 0.012 $/Nm3 H2 produced was achieved under the optimal operating condition. Sensitivity analysis on the H2 loss and H2 purity indicates that such membrane is still less cost-effective to achieve ultrapure hydrogen (e.g., >99.8 vol %) unless the higher operating temperatures for carbon membrane systems are applied.

Automated summary

Asymmetric carbon molecular sieve (CMS) membranes prepared from cellulose hollow fiber precursors show excellent separation performance and high stability for H2/CO2 separation. A two-stage carbon membrane system is found to be technologically and economically feasible for producing high-purity H2. It is suggested that higher operating temperatures are needed to achieve higher purity hydrogen.