Products and Global Weight Loss Rates of Wood Decomposition Catalyzed by Zinc Chloride

Motivated by the production of fine chemicals and the improvement of flame retardance properties, experiments have been performed with a fixed-bed reactor to investigate the catalytic action exerted by zinc chloride on fir wood pyrolysis (catalyst concentrations between 0 and 16% on a dry wood basis and heating temperatures between 650 and 900 K). It has been observed that this Lewis acid acts as a dehydrating and cross-linking agent promoting the formation of char and water with total yields up to about 73%. As a consequence, the majority of organic condensable products generated from uncatalyzed pyrolysis of wood (hydroxyacetaldehyde, hydroxypropanone, levoglucosan, and other minor carbohydrates, phenols, and guaiacols) is rapidly reduced to low values. However, zinc chloride is a particularly effective catalyst (concentrations of 1-6% and temperatures of 700-800 K) to maximize the yields of levoglucosenone, acetylfuran, 5-methyl-2- furaldehyde, and, especially, 2-furaldehyde which is augmented by a factor of 5. Zinc chloride also introduces good fire retardance properties of wood as testified, in addition to the enhanced formation of char and water, by the halving of the release rate of flammable volatile species and the five-factor increment in the ratio of noncombustible to combustible volatile product yields.