Nanoporous Carbon Membranes for CO2 Capture
Capture and storage of carbon dioxide (CO2) is considered to have a significant role in the near-term reduction of CO2 emissions and therefore to slow global warming. Nanoporous carbon (NPC) membranes show promise as a new generation of gas separation membranes suitable for CO2 capture.
Made from the pyrolysis (heating) of a polymer, a NPC membrane is an amorphous carbon network with pores smaller than one nanometer that allows the separation of gases through a molecular sieving mechanism. Molecular simulations suggest that the performance of NPC membranes will be an order of magnitude better than the current commercial polymeric membranes.
We have manufactured supported NPC membranes by spin coating polyfurfuryl alcohol (PFA) onto a porous stainless steel support followed by pyrolysis under argon at 400°C.
The NPC membranes made display CO2/CH4 permselectivities as high as 15, which is further increased to a selectivity of 21 when tested with a mixed CH4:CO2 feed (90:10 vol%). It was also determined that increasing the membrane operating temperature from 35°C to 125°C decreases the selectivity from 21 to 9 due to the disproportional increase in the methane permeance. The performance of the NPC membranes also decreases with time. Recovery of 80% of the original performance can be achieved using a nitrogen (N2) purge at 120°C prior to testing