PYROLYSIS OF LIGNINS IN MOLTEN-SALT MEDIA

Two kinds of lignins, i.e., kraft and solvolysis lignins, were pyrolyzed using mixtures of molten ZnCl2 and KCl with molar ratios of 3/7 and 7/6 over the temperature range of 500-800-degrees-C under atmospheric pressure. The yields of gaseous products and of phenolic compounds were measured. It was found that the variation of gaseous product yield with temperature was similar in pattern, irrespective of the lignin type. A higher yield of H-2 implies that the H2O-forming reaction was partially retarded. It was also found that the mixture of molten ZnCl2 and KCl with molar ratio of 7/6 had a high selectivity to cresols. The maximum yield of cresols from solvolysis lignin reached 4.6 wt %, higher than any figures reported so far. This maximum yield was attained at 600-degrees-C.