Use of steel slag as a catalyst in CO2-cofeeding pyrolysis of pine sawdust

Abstract

To seek an innovative way for simultaneous waste management and energy recovery, two waste materials (pine sawdust: PSD and steel slag: SS) were used in the pyrolysis process. PSD was used as a carbonaceous material for pyrolysis, and SS was used as a catalyst. Also, to achieve a more sustainable conversion system, a viable use of carbon dioxide (CO2) as a raw material in the non-catalytic/catalytic pyrolysis process was evaluated. Hence, the present study laid great stress on the CO2 effects. The present study pointed the optimistic technical features in line with the use of CO2 in the pyrolysis process. Exploiting CO2 in pyrolysis of PSD offered a strategic way to control carbon reallocation from liquid to gaseous pyrolysates by the gas phase reactions (GPRs). The reactions of CO2 and volatile pyrolysates led to CO enhancement, which was only observed at ≥ 600 °C due to the slow reaction kinetics of the GPRs of volatile pyrolysates and CO2. Such the slow reaction kinetics was expedited remarkably when SS was acted as a catalyst. Moreover, CO2 expedited thermal cracking of volatile pyrolysates including dehydrogenation, which led to the enhanced formation of CH4 and H2.