Journal of Analytical and Applied Pyrolysis, 14 (1989) 281-294 zyxwvutsrqponmlkjihgfedcbaZYXWVU Elsevier Science Publishers B.V.. Amsterdam - Printed in The Netherlands 281 zyxwvutsrqp CHARACTERIZATION OF THE SOLID RESIDUES OF VACUUM PYROLYSIS OF zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC POPUL US TREMULOIDES A. AHMED, H. PAKDEL, C. ROY and S. KALIAGUINE * Department of Chemical Engineering and GRA PS, UniversitC LA VAL., Q&bee (Canada) (Received May 2nd, 1988; accepted August 26th, 1988) ABSTRACT Bulk chemical analyses and surface composition ESCA results are reported for the solid residues of vacuum pyrolysis of Populus tremuloides. The conversions of hemicellulose and lignin start as low as 207 o C, but below 280 o C the conversion products of lignin are mostly solids. Cellulose is converted to oil and gas above 280°C but some of these products undergo secondary recondensation reactions which involve lignin degradation solid products. The char obtained above 315O C mostly consists of polyaromatic materials. The ESCA analysis of chars produced from extracted and non-extracted wood indicate the presence of extractives with hydrocarbon chains on the surface of the fibers. These heavy components seem very resistant to thermal degradation and remain on the surface of the residues up to 400 o C even under vacuum conditions. The effect of these extractives on the liquefaction of wood is discussed. ESCA; lignin; Populus tremuloides; pyrolysis. INTRODUCTION In a series of articles [l-4] we have reported analytical results, including ESCA analysis, of solid residues prepared by supercritical extraction (SCE) of Populu.s tremuloides in methanol. Analytical techniques usually utilized for the characterization of lignin, cellulose and hemicellulose in wood [5,6] were adapted for the analysis of SCE solid residues. Such methods are of course applicable to any kind of thermally degraded lignocellulosic materi- als, and they may therefore provide information about the mechanistic differences between the various wood liquefaction processes. In the present paper these analytical techniques were applied to the solid residues obtained by vacuum pyrolysis of Populus tremuloides, with special emphasis on the use of the ESCA technique. 01652370/ 89/ $03.50 0 1989 Elsevier Science Publishers B.V.