Carbon Membranes from Wood Materials and their Separation Properties

Abstract

Carbon membranes were prepared by coating thin layers of lignocresol derived from Hinoki cypress by the phase-separation method and then carbonizing the lignocresol by high frequency induction heating at a heating rate of 500°C/min. The thickness of the membrane formed on the outer surface of a porous alumina substrate was about 1000 nm. Carbon membrane with a high performance of gas permeation showed a high water-selectivity in pervaporation of water/alcohol separation. The separation factor increased with increasing the heating temperature. The water concentration of the permeate was more than 99.5 wt% and the water flux was more than one or two order larger than the alcohol flux in the membrane prepared at 600 or 700°C. Carbon membranes derived from lignin-based materials provide one of the promising candidates for the separation of the liquid mixtures.

Structure and Separation Performance of Carbon Membranes from Lignin-based Materials

“…The thermogravimetric analysis of the lignocresol [7] showed that the weight of lignocresol decreased by approximately 45% in the range of 350-450ºC and then gradually decreased by 55% at 800ºC. The gaseous products evolved from the lignocresol included methylphenol, dimethylphenol and several compounds with higher molecular weight together with traces of carbon dioxide and methanol.…”

“…6 Gas permeation rates (R) at 35ºC and 1 atm through lignocresol membranes carbonized at 600ºC and 700ºC for 10 min in nitrogen atmosphere. 34 [3] 371-374 (2009) Transaction of the Materials Research Society of Japan Carbon membranes derived from lignocresol with a high performance of gas permeation also showed a high water-selectivity in pervaporation of water/alcohol separation [8].…”

“…Such lignin derivatives having a linear structure offer greater versatility and are particularly suitable for the replacement of the phenolic products from fossil resources. Thus, in our recent reports [5][6][7][8], we chose lignocresol as novel precursor membrane materials for carbon molecular sieving membranes on the basis of high carbon yield and good film-forming properties without a pinhole during pyrolysis. Resulting membranes showed both higher permeability and higher selectivity than presently available polymers.…”

Review on the preparation of carbon membranes derived from phenolic resins for gas separation: From petrochemical precursors to bioresources

“…although it may open up a space for new research. In this sense, lignocresols, as polyphenolic extracts of lignocellulose and other liquefied wood products, represented an approach to synthesise CMSMs for gas separation [182][183][184][185][186][187]. Pyrolysis of these precursors was carried out over a temperature range of 400-800 °C and under vacuum or N 2 atmosphere.…”

“…In the works of the research group of Kita et al and Koga et al[182][183][184][185], a lignocresol fraction was extracted from a lignin matrix by a phase-separation treatment with p-cresol and sulphuric acid. This phenolic fraction was mixed with methyl ethyl ketone and used to coat the outer face of an alumina tube.…”