2014 Volume 93 Issue 10 Pages 944-952
In fast catalytic pyrolysis of eucalyptus as woody biomass, zeolites enhanced the formation of aromatic hydrocarbons with and without O-atoms, mainly. H-ZSM-5 and H-Beta zeolites were efficient for the formation of non-oxygenated aromatic compounds. High Si/Al2 ratio in H-ZSM-5 depressed the formation of non-oxygenated aromatics, while high Si/Al2 ratio in H-Beta kept high yield of non-oxygenated aromatics. H-mordenite and USY showed a moderate catalytic activity for the formation of phenolic compounds as well as non-oxygenated aromatics, due to moderate catalytic properties. Aromatic compounds may be derived from cellulose, hemicellulose and lignin. In the case of cellulose or hemicellulose as source of aromatics, oxygenated intermediates were formed by thermal decomposition of cellulose or hemicellulose, followed by reaction to form aromatic compounds. In the case of lignin source, oxygenated aromatics were formed by thermal decomposition of lignin, followed by deoxygenation to form non-oxygenated aromatics. Strong solid acidity favors deoxygenation reaction. Moderate solid acidity leads to the formation of phenolic compounds. Large micropore diameter and 3-dimensional microstructure have advantage, since intermediates can contact active sites inside the micropore. Except for SAPO-34, 4A, 13X and Ti-silicate, exhibiting significantly low yield of both of non-oxygenated aromatics and phenols, there seems to be an inversed correlation between yield of non-oxygenated aromatic compounds and that of phenolic compounds.