Catalytic pyrolysis of low-rank coal using Fe-carbon composite as a catalyst

In this study, CO₂-cofeeding pyrolysis of low-rank coal (LRC) was performed to quest the mechanistic effects of CO₂ on the CO enhancement. The thermogravimetric analysis (TGA) test and lab-scale pyrolysis of LRC informed that CO₂ and tar were reacted by the gas phase reaction. The gas phase reaction of CO₂ and tar led to the different carbon distribution in liquid pyrolysate, and it was experimentally justified by mass balance of three pyrogenic products and the CO enhancement. To expedite the CO enhancement by CO₂, the catalytic capability of LRC char was also investigated. For the fundamental study, inorganics in LRC was removed through the acid-washing process, which experimentally proved that the catalytic capability was imparted from inorganics in LRC. All findings in this study suggested that the exploitation of CO₂ in pyrolysis of LRC offers the better opportunity in terms of the CO₂ conversion into CO. Also, the CO enhancement can be further expedited catalytically. Such facts greatly offer a technical benefit that the exploitation of LRC in reference to high rank coal (HRC) can be an ideal carbon source because the CO₂ susceptibility resulting in the CO₂ enhancement by consuming tar is highly dependent on the volatile carbon content.