Slow pyrolysis of bio-oil and studies on chemical and physical properties of the resulting new bio-carbon

This paper describes the conversion of bio-oil into bio-carbon by using slow pyrolysis. The effects of two different temperatures (600 degrees C and 900 degrees C) and residence times (30 min and 60 min) on the morphology, elemental composition, thermal stability, functionality, as well as the thermal and electrical conductivity of the produced bio-carbon were investigated. Overall, it was found that differences in the residence time at the same temperature have no relevant effects on the elemental composition of the samples. Temperatures of pyrolysis of 900 degrees C were found to have a direct impact in the morphology of the synthesized bio-carbon. In general, X-ray diffraction showed the presence of amorphous carbon combined with hexagonal graphitic planes (002). However, it was found that the d-spacing between adjacent graphitic planes is reduced at higher temperatures of pyrolysis. The elemental and spectroscopic assessment also indicated that pyrolysis at 900 degrees C leads to a higher reduction of oxygen (O) and hydrogen (H) compared to samples processed at 600 degrees C resulting in more pure forms of bio-carbon and a better thermal stability. A tendency of the electrical conductivity to decrease and the thermal conductivity to increase was found with the increase in the temperature of pyrolysis. (C) 2017 Elsevier Ltd. All rights reserved.