(2020) Journal of Hazardous Materials_CO₂-cofed catalytic pyrolysis of tea waste over Ni/SiO₂ for the enhanced formation of syngas

Kim J.-H., Jung S., Park Y.-K., Kwon E.E.

(Elsevier B.V.) Journal of Hazardous Materials ISSN: 3043894 Vol.396 Issue. Article No.122637 DOI: 10.1016/j.jhazmat.2020.122637

To valorize tea waste (TW), catalytic pyrolysis was done as a practical measure for recovering energy as a form of syngas. Considering CO₂ as a reactive gas medium in place of conventional pyrolysis gas, a sustainable pyrolysis platform was established. In addition, mechanistic effectiveness of CO₂ on TW pyrolysis was examined. In the presence of CO₂, homogeneous reaction with volatile organic compounds (VOCs) derived from TW pyrolysis contributed to CO formation. To enhance the formation of syngas at low pyrolysis temperature, catalytic pyrolysis over a Ni/SiO₂ was investigated. The synergistic effects of Ni/SiO₂ catalyst and CO₂ promoted thermal cracking of VOCs and further homogeneous reaction with CO₂, thereby resulting in the substantial enhancement (28 times more) of H₂ and CO production than non-catalytic pyrolysis. It was also confirmed that CO₂ could be considered a reactive gas medium to produce biochar (34–35 wt.% yield), having competitive porosity and surface area, in comparison to that from pyrolysis in N₂. Therefore, CO₂ can be employed to build a sustainable waste conversion platform for energy and biochar production through pyrolysis instead of using N2. © 2020 Elsevier B.V.

This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIT) ( NRF-2019R1A4A1027795 and NRF-2019H1D3A1A01070644 ).