Influences of pyrolysis conditions in the production and chemical composition of the bio-oils from fast pyrolysis of sewage sludge

摘要

Fast pyrolysis of sewage sludge (SS) was investigated in a drop tube furnace to understand the effects of pyrolysis temperature and sweeping gas flow rate (SGFR) on the yields and chemical composition of pyrolysis products. The bio-oil yield reached ca. 45.3% at 500 ℃ and a SGFR of 300 mL/min. The bio-oils were analyzed with an elemental analyzer, Fourier transformation infrared spectrometer, and gas chro-matograph/mass spectrometer. The chemical composition of the bio-oil significantly depended on the pyrolysis temperature. The bio-oils obtained at low temperatures are species, such as alkenes, alkanes, long-chain fatty acids and esters, and aliphatic nitriles and amides. At high temperatures, aliphatic and thermally labile organooxygen species were mainly cracked to gaseous products, while the organonitro-gen species tended to form aromatic species, especially N-heterocyclic ones. Because of its high nitrogen content, the SS bio-oil is unfeasible for use as fuel feedstock, but possible for use as chemical feedstock. This study provides a basic insight into the preparation and characterization of bio-oil from SS, which would facilitate the use of the bio-oil both as clean fuel and value-added chemical.