(2020) Energy Conversion and Management_CO₂-Mediated catalytic pyrolysis of rice straw for syngas production and power generation

Jung S., Lee S., Park Y.-K., Lee K.H., Kwon E.E.

(Elsevier Ltd) Energy Conversion and Management ISSN: 1968904 Vol.220 Issue. Article No.113057 DOI: 10.1016/j.enconman.2020.113057

As emissions of anthropogenic CO₂ from the use of fossil fuels become more severe, the renewable energy production has received considerable interests. In this study, CO₂ was used as a raw material to produce energy as a form of syngas (H₂/CO) as a precautious measure for mitigating the atmospheric CO₂ levels. Rice straw pyrolysis was conducted under various N₂/CO₂ purge gas environments. The present study experimentally proved that CO₂ expedited gas phase homogeneous reactions between volatile organic compounds (VOCs), evolved from rice straw pyrolysis. These CO₂ functionalities led to the conversion CO₂/rice straw into CO at ≥ 480°C. To accelerate reaction kinetics of syngas formation, additional thermal energy (500 or 700°C) was applied through multi-stage pyrolysis setups. In addition, SiO₂ supported Co (Co/SiO₂) catalyst was further accelerate reaction kinetics of CO (3 times) and H₂ (6 times) in reference to non-catalytic pyrolysis at 500°C. The synergistic effects of Co/SiO₂ catalyst and CO₂ feedstock resulted in substantial formations of H₂ and CO at ≤ 480°C. To analyze the potential capability of rice straw fuels, their power generation performances were evaluated through a simple gas turbine cycle. When the constant amount of air was assumed to be supplied to a combustion chamber, different amounts of fuel feedstocks were required for their complete combustions. In this condition, the resulting power generations of rice straw fuels (maximum 138 MJ s⁻¹ from catalytic pyrolysis under 100% CO₂) were up to 1.9 times higher than the power generations from natural gas references (74 and 82 MJ s⁻¹). These results suggest that a renewable power generation platform could be constructed with a valorization of greenhouse gas (CO₂) and biomass waste (rice straw) through pyrolysis process at mild temperature. © 2020 Elsevier Ltd

This work is financially supported by Korea Ministry of Environment (MOE) as Graduate School specialized in Climate Change.