Catalytic upgrading of coal pyrolysis products over bio-char

Several reactions parallel happened during co-pyrolysis of coal and biomass, such as primary volatiles of coal and biomass will contact and react with the nascent char from coal or biomass themselves' pyrolyzed. To clarify the function of bio-char and investigate if bio-char has the catalytic effect on pyrolysis products of Hulunbuir lignite, a two-stage reactor is designed and used in this study. The effects of bio-char preparing temperature, char-making method and usage amount of bio-char were discussed. In comparison with the alone coal pyrolysis at 650 °C, the portion of light tar (n-hexane soluble) from pyrolysis of coal with bio-char (20 wt% of coal), increased by 30.31%, gas volume yield increased by 9.05% and the volume yield of hydrogen and methane increased by 6.36% and 5.64%, respectively. For the most efficient RSCR-700 against the test with quartz, the H/C molar ratio in RSCR-700's produced tar increased by 22.06%, while the contents of N and S elements decreased by 27.88% and 25.0% accordingly. The role of bio-char in the coal tar upgrading process was further explored through the instruments characterization. Besides the thermal cracking, the bio-char also can provide catalytic active sites to crack heavy fraction of coal tar.