HEAT-TREATMENT OF ROCKROSE CHAR IN AIR - EFFECT ON SURFACE-CHEMISTRY AND POROUS TEXTURE

The surface chemistry and the porous texture of activated carbons prep ared from a charred product (C-lex-600), which was obtained from rockr ose (Cistus ladaniferus, L.) extracted previously into petroleum ether , were studied. Activated carbons were prepared by heating C-Jex-600 b etween 350 and 850 degrees C in air to 40% burnoff. Methods of chemica l analysis and FTIR spectroscopy as well as techniques of gas adsorpti on (N-2, 77 K; CO2, 298 K), mercury porosimetry, and density measureme nts were applied. In the FTIR study of the samples, the presence of su rface olefinic C=C double bonds, aromatic rings, and oxygen functional groups was detected. Carbonyl groups were only found to a significant extent in C-Jex-600 and in the activated carbon prepared at 350 degre es C. The microporosity developed with increasing temperature between 350 and 750 degrees C. At higher temperatures, pore narrowings occurre d. The gasifying action of air was strongly dependent on the removal o f nonorganized matter from C-Jex-600 and on the pore size. The reactio n time needed at 850 degrees C in air to reach burnoff 40% was less th an a half of that at 350 degrees C, and was comparable to the times re quired in CO2 and steam under the same experimental conditions. Copyri ght (C) 1996 Elsevier Science Ltd