Carbon molecular sieve (CMS) membranes have been studied for more than 20 years as promising and energy-efficient membranes for gas separation. Due to their high permeability and selectivity, as well as their high thermal and chemical stability under adverse and harsh conditions, CMS membranes are becoming increasingly important for separating gas mixtures with quite similar molecular kinetic diameter. Carbon molecular sieve membranes can be prepared by controlling the carbonization procedure during carbonization of a polymeric material. The effects of carbonization parameters (final temperature, heating rate, soak time and atmosphere during carbonization) on the resulting carbon membrane performance can be investigated, and the optimal condition can be found to prepare the high performance carbon membranes for a specific application. Several general techniques of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction can be employed to characterize the membrane's structure and morphology. Moreover, the pore size and pore size distribution can be estimated by gas gravimetric adsorption measurements, which will be helpful in understanding the transport mechanism through carbon membranes. The operating conditions will greatly affect the CMS membranes separation performances and need to be optimized for the application. Considering the aging problem for carbon membranes, different regeneration techniques can be used to recover the performances on-line or off-line. In order to ensure the efficiency of the carbon membrane separation process, the membrane module should be prepared as hollow fibers, and the process designed according to the given process conditions and economic considerations. Based on the experimental investigations and process simulations, the carbon membranes show high potential for selected industrial applications such as CO2–CH4 separation for biogas upgrading, H2–CH4 separation wherever relevant, CO2 capture from flue gases, air separation, petrochemical and high-temperature applications.
|Title of host publication||Membrane Engineering for the Treatment of Gases: Volume 2: Gas-separation Problems Combined with Membrane Reactors|
|Editors||Enrico Drioli, Giuseppe Barbieri|
|Publisher||Royal Society of Chemistry|
|State||Published - 21 Jul 2011|