(2020) Chemical Engineering Journal_Functional use of CO₂ for environmentally benign production of hydrogen through catalytic pyrolysis of polymeric waste

Jung S., Choi D., Park Y.-K., Tsang Y.F., Klinghoffer N.B., Kim K.-H., Kwon E.E.

(Elsevier B.V.) Chemical Engineering Journal ISSN: 13858947 Vol.399 Issue. Article No.125889 DOI: 10.1016/j.cej.2020.125889

A benign route for hydrogen (H₂) production is environmentally desirable. To achieve this, H₂ synthesis from polymeric waste was investigated. A new route was sought to maximize H₂ production with the least formation of coke during catalytic pyrolysis of fishing net waste (FNW) by using CO2 (as reaction media) and a Ni/SiO₂ (as catalyst). The thermolytic characteristics of FNW were also evaluated under the CO₂ condition (and N₂ as reference environment) both with and without catalysts to assess the full scope of variabilities involved in catalytic pyrolysis of FNW. The use of Ni/SiO₂ catalyst in each of the N₂ and CO₂ conditions improved the reaction kinetics in terms of syngas formation with significant production of H₂ (1,543 and 770 mmol g⁻¹cat h⁻¹) and CO (11 and 1157 mmol g⁻¹cat h⁻¹), respectively. However, H₂ production rate dropped when the catalyst was deactivated due to (hydro)carbon deposition onto the catalyst surface under N₂ environment. Under CO₂ environment, CO₂ served as an oxidant during FNW thermolysis with additional CO formation and prolonged lifetime of catalyst (via suppressed deactivation). H₂ production mediated by CO₂ increased to ≥1,093 mmol g⁻¹cat h⁻¹ during five repeated cycles of FNW pyrolysis, coupling with water–gas shift reaction (WGS: CO+H₂O⇌H₂+CO₂). This new approach to H₂ production is demonstrated as a practical measure for producing H₂ while extending catalyst life. © 2020 Elsevier B.V.

This work was supported by National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (NRF-2019R1A4A1027795 and NRF-2019H1D3A1A01070644).