Effect of heat treatment on wood chemical composition, extraction yield and quality of the extractives of some wood species by the use of molybdenum catalysts

Abstract

The effect of heat treatment and the presence of some molybdenum catalysts on the amount of extractives in Populus nigra, Larix decidua, Paulownia tomentosa, Castanea sativa and Quercus frainetto wood were studied. There are an increase in the amount of lignin and extractives and a decrease in the amount of holocellulose following thermo-treatment, in the treatment temperature range. Autoclave treatment of wood with water in the presence of some molybdenum catalysts can increase the amount of extracts, but it reduces solubility. Soxhlet extraction of wood with ethanol/toluene mixture in the presence of H3PMo12O40 increases the amount of extractives and their solubility in chloroform, while in the presence of MoO3 only the solubility of extractives increases. GC–MS analysis of insoluble fraction showed the presence of myo-inositol and some simple carbohydrates, mainly ribose, xylose and glucose. GC–MS analysis of soluble fraction showed the presence of long-chain acids and fatty acid esters of 10–20 carbon atoms, mainly decanoic acid, hexadecanoic acid and octadecanoic acid, which can be a source of fatty acids for biodiesel production.