Porous structure and surface chemistry of nitrogen containing carbons from polymers

Active carbons containing up to 4.5% nitrogen (SCN-type carbons) were prepared by carbonization in argon and steam activation of a vinylpyridine resin. The porous structure of the SCN carbons with different burn-off values was characterized by gas adsorption (N-2 and CO2), mercury porosimetry and helium pycnometry. The SCN carbons exhibit micro- and mesoporosities, which may be regulated. By microcalorimetric and water adsorption methods it was shown, that SCN carbons present a higher surface polarity than carbons without nitrogen. The nitrogen atoms in the carbon structure behave as polar sites. The nitrogen chemistry investigated by XPS analysis is discussed. The nitrogen chemical functions in SCN carbons are transformed during heat treatment. In the char obtained at 1223 K and samples of activated carbons, the nitrogen is present in the six-membered rings of the polyaromatic structures. (C) 1999 Elsevier Science Ltd. All rights reserved.