Catalytic pyrolytic platform for scrap tires using CO2 and steel slag

• Published in: Applied energy 2020-02, Vol.259, p.114164, Article 114164
• Main Authors: Cho, Seong-Heon, Oh, Jeong-Ik, Jung, Sungyup, Park, Young-Kwon, Tsang, Yiu Fai, Ok, Yong Sik, Kwon, Eilhann E.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Catalysis; Pyrolysis; Scrap tire; Steel slag; Waste-to-energy
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2019.114164

•CO2 plays a role for modifying the compositional matrix of pyrolytic oil and gas.•Lowering aromaticity of pyrolytic oil by CO2 restrict the formation of PAHs.•CO2 can be used in-situ reaction medium for air pollution controls (APCs).•CO2 offers an opportunity to enhance the formation of H2. This study specifically examined CO2-cofeeding pyrolysis of scrap tire (ST) to enhance H2 generation. Thus, volatile pyrolysates (syngas and pyrolytic oil) from the thermolysis of ST in N2 and CO2 were compared to elucidate the mechanistic roles of CO2. To this end, laboratory scale of pyrolysis of ST from N2 and CO2 was conducted in this study. The gaseous effluents from a pyrolyzer showed that enhanced CO evolution only from CO2-cofeeding pyrolysis of ST. Moreover, a substantial decrease in the formation of benzene derivatives (BDs) including polycyclic aromatic hydrocarbons (PAHs) was discovered from CO2-cofeeding pyrolysis of ST. Those findings offered that CO2 could improve pyrolysis of ST by modifying the pyrogenic products, and those enhanced pyrolysis behaviors were ascribed to the homogeneous interaction between CO2 and pyrolysates from the pyrolysis of ST (more CO generation). To advance the identified roles of CO2, catalytic pyrolysis of ST in CO2 was carried out using steel slag (SS) as a catalyst. In the presence of SS, the effectiveness of CO2 on pyrolysis of ST was dramatically enhanced (~400% enhancement at 400 °C). Therefore, this study experimentally justified that the utilization of SS could alleviate the environmental burdens by adopting CO2 in pyrolysis of ST. Also, the CO enhancement by CO2 likely leads to the H2 enhancement when the water-gas-shift (WGS) reaction was also conducted. All experimental findings from this study suggested that the use of CO2 in pyrolysis of ST could be a breakthrough to enhance H2 formation.