Abstract
Gas and char formation from guaiacol as lignin model compound in sub- and supercritical water (SCW) was conducted in a continuous flow system for 300-450 ℃ and 25 MPa at short residence time of 0.5-40 s. Both char and gaseous formation are qualitatively and quantitatively determined to establish its yield and its formation trend with temperature and residence time. The high yields of CO_2, H_2, CH_4, and zero CO indicates that the gaseous compounds are produced from direct decompositions of guaiacol and its derivative compounds instead of reaction among gas species and water. On the other hand, there is significant higher yield of char in supercritical region. It is established that gas-forming reactions are competing with cross-linking between the reactive degradation fragments from the degraded lignin to form char.
