Carbon Molecular Sieve Membranes Derived from Phenolic Resin with a Pendant Sulfonic Acid Group

Abstract

A thermosetting phenolic resin with a pendant sulfonic acid group was prepared by reacting a resol-type phenolic resin (PF) with a Novalak-type sulfonated phenolic resin (SPF). Large amounts of gaseous molecules with similar and small size such as H2O and SO2 evolved in the range of 110 and 350 °C during the pyrolysis of this thermosetting phenolic resin (PF/SPF). Highly permeable carbon molecular sieve (CMS) membranes were obtained by pyrolysis of PF/SPF(45/55) precursor membranes which were dip-coated on porous alumina tubes. For example, the membrane pyrolyzed at 500 °C for 1.5 h displayed H2, CO2, and O2 permeances of 1950, 800, and 240 [GPU (gas permeation units) = 10-6 cm3(STP)·s-1·cm-2·cmHg-1], respectively, and ideal H2/CH4, CO2/CH4, and O2/N2 separation factors of 65, 27, and 5.2 at 35 °C and 1 atm, respectively. Sulfonic acid groups linked to thermostable polymer chains might act as “bonded templates” and showed attractive potential in the preparation of CMS membranes.