Carbon Membranes Prepared from Poly (Furfuryl Alcohol–Furfural) Precursors: Effect of FeCl₃ Additive

Abstract

Thermosetting resins, such as poly (furfuryl alcohol), are efficient precursors for preparation of carbon membranes with molecular sieving properties. Polymerization of furfuryl alcohol is catalyzed by Bronsted or Lewis acids. FeCl3, showing Lewis-acid behavior, is an interesting polymerization catalyst, because it gets reduced into metallic iron during pyrolysis of the resin, promoting transformation of amorphous carbon into graphitic domains. The goal of the present work was to examine whether use of FeCl3 as a polymerization catalyst of furfuryl alcohol–furfural mixtures could lead to preparation of carbon membranes with improved gas separation performance compared to those prepared with use of p-toluenesulfonic acid. The resins were deposited onto tubular porous ceramic supports and pyrolyzed at temperatures in the range of 500–1000 °C. Material characterization was carried out by X-Ray Diffraction, N2 physisorption, Raman spectroscopy and Scanning Electron Microscopy. The membrane performance was examined using H2, CO2 and CH4 as probe molecules. It was found that the membranes operate mainly via the molecular sieving mechanism and the use of FeCl3 instead of p-toluenesulfonic acid does not lead to an improvement in the permeation characteristics of the respective membranes.

Keywords

• carbon membrane
• hydrogen
• carbon dioxide
• methane
• furfuryl alcohol
• furfural