ORGANIC-CHEMICAL STRUCTURE AND STRUCTURAL SHRINKAGE OF CHARS PREPAREDFROM ROCKROSE

Chars were prepared by heating rockrose (Cistus ladaniferus L) under d ynamic and isothermal conditions between 200 and 1000 degrees C in nit rogen. Several techniques including chemical analysis, Fourier transfo rm infrared (FTIR) spectroscopy, molecular simulation, density measure ments, mercury porosimetry and adsorption were used to study the chemi cal structure and pore structure. The chars prepared at high temperatu res in particular contain oxygen in ether type structures, which may c ross-link aromatic sheets. The degree of development of porosity in th e chars and the porosity distribution seem to depend on the amount of volatile matter removed at each temperature during pyrolysis and on th e structural shrinkage of the residual carbon. Both factors act contra rily on the pore structure of the chars, the latter effect being stron ger at high temperatures. The shrinkage of the carbon structure may be caused by break down of interlayer carbon-oxygen bonds. (C) 1998 Else vier Science Ltd. All rights reserved.