Characteristics of Chars Prepared by Low-Temperature Co-Pyrolysis of Lignite and Biomass

Low-temperature co-pyrolysis of lignite coal and biomass blends was studied at different ratios using a fixed bed reactor and a thermogravimetric analyzer (TGA). The results show that the addition of biomass during low-temperature pyrolysis was found to promote the collapse of macro-pores, leading to the formation of more fine meso-pores in chars. As a stabilizer the hydrogen atoms produced from the pyrolysis of biomass samples reacted with the radical fragments which inhibited the polymerization, and resulted in an increase in the tar and gases yields. The effect of hydrogen from co-pyrolysis on the chemical structure of char was obvious. The combustion reactivity of co-pyrolysis chars was lower than that of lignite char, indicating that the content of volatile is more important than the pore structure and oxygen-containing groups to combustion reactivity for biomass/lignite char obtained from low-temperature co-pyrolysis.