Canadian Journal of Chemical Engineering, Vol.77, No.6, 1176-1184, 1999
Pyrolysis of kraft lignin in the presence of molten ZnCl2-KCl mixture
Pyrolysis of kraft lignin was carried out using small reactors with an added ZnCl2-KCl mixture at three levels of temperature, 500 degrees C, 550 degrees C and 600 degrees C, and three levels of salt-to-lignin ratio (SR), 1, 2 and 3. Nineteen kinds of phenolic compound were identified and their quantitative determinations were made by gas chromatography. The yield of gaseous products determined gravimetrically exhibited a strong dependence on the added amount of salt mixture, and its lowest value was obtained at SR of 1. The formation of gaseous products, apparently stemming from decomposition of liquid products and tar, was observed at reaction times longer than 30 min. At SR of 1 and a temperature of 550 degrees C, all phenolic compounds attained their maximum yields almost synchronously at a reaction time of 15 min. Cresol's formation was slightly increased with the amount of added salt mixture. At a temperature of 550 degrees C, cresols and guaiacols decomposed according to a pseudo-first-order lumping model, while catechols did not follow the similar model.
Keywords:KINETICS