Screening heterogeneous catalysts for the pyrolysis of lignin

The pyrolytic conversion of pure lignin at 600 °C in flowing helium over five catalysts is described and compared to the control bed material, sand. Product distribution as char, liquid, and gas are described as well as the composition of the liquid and gas fractions. The catalysts examined were HZSM-5, KZSM-5, Al-MCM-41, solid phosphoric acid, and a hydrotreating catalyst, (Co/Mo/Al2O3). The sand yielded a liquid phase that was 97% oxygenated aromatics and a gas phase that was CO (18 vol%), CO2 (16 vol%), and CH4 (12 vol%). HZSM-5 was the best catalyst for producing a deoxygenated liquid fraction yielded almost equal amounts of simple aromatics (46.7%) and naphthalenic ring compounds (46.2%). The gas phase over this catalyst consisted of CO (22 vol%), CO2 (14 vol%), H2 (12 vol%), and CH4 (10 vol%). The Co/Mo/Al2O3 hydrotreating catalyst yielded a liquid consisting of 21% aromatics, 4% naphthalenics, and 75% oxygenated aromatics and a gas phase that was rich in hydrogen: H2 (18 vol%), CO2 (16 vol%), CO (12 vol%), and CH4 (8 vol%).