Pore size control of microporous carbon membranes by post-synthesis activation and their use in a membrane reactor for dehydrogenation of methylcyclohexane

Hydrogen-permselective carbon membranes were prepared by a vapor-phase synthesis using furfuryl alcohol as a carbon source. Their pore sizes were evaluated from the molecular sieving properties by single gas permeations of H2, CO2, CH4 and CF4. The pore size of the carbon membranes was increased by a post-synthesis activation using various gases and vapors such as H2, CO2, O2 and steam. The activation using H2 was the most effective for improving both the H2 permeance and permselectivity because the molecular size of H2 is smaller than the pore size of the carbon membrane and can react with the inner surface of the carbon membrane. After the activation using H2 at 973 K, the pore size of the carbon membrane was increased from 0.30 to 0.45 nm, and the permeance of H2 was increased from 3.6×10−9 to 1.6×10−8 mol m−2 s−1 Pa−1. The activated carbon membrane was used in a membrane reactor for dehydrogenation of methylcyclohexane and showed potential for application in the dehydrogenation of chemical hydrides in membrane reactors.