(46i) Carbon Molecular Sieve Membranes Derived from Lignin-Based Materials

It is important to produce functional materials from renewable resources, and not from fossil resources, in order to sustain the production of materials for human life under a sound ecological system. Among renewable resources the forest provides excellent raw materials, carbohydrates(cellulose and hemicellulose) and polyphenol(lignin) in both quantity and quality. Although the carbohydrates have been incorporated into human life for a long time, lignin has scarcely been utilized. Here, we report the preparation of carbon membranes by coating thin layers of lignocresol derived from lignin by the phase-separation method and then carbonizing the lignocresol by high frequency induction heating at a heating rate of 500ºC/min or conventional tube reactors at a heating rate of 5 ºC/min. The thickness of the membrane formed on the outer surface of a porous alumina substrate was about 400-1000 nm judging from SEM observation. Gas permeation rates through the membranes were measured at 35 ºC and 1 atm using a vacuum time-lag method. Carbon membranes derived from lignin-based materials provide one of the promising candidates for high performance membrane. Especially, the carbon membrane prepared by rapid pyrolysis shows a high permeance, which can be attributed to a more open structure of the membrane.