(2024) Chemical Engineering Journal_Using CO₂ in cultivation of microalgal biomass and thermo-chemical process

Park J.; Cho S.-H.; Jung S.; Lee J.S.; Tsang Y.F.; Sim S.J.; Kwon E.E.

(Elsevier B.V.) Chemical Engineering Journal ISSN: 13858947 Vol.484 Issue. Article No.149700 DOI: 10.1016/j.cej.2024.149700

Microalgal biomass is a promising candidate for next generation biorefinery resources because of its rapid growth rate and efficiency in carbon assimilation. Recent studies have reported successful microalgal cultivation using exhaust gases rich in CO₂ as the carbon source. This study focuses on optimising carbon utilisation by incorporating CO₂ into the pyrolysis process of microalgae, particularly Scenedesmus sp., cultivated under elevated CO₂ concentrations. Under the influence of CO₂, homogeneous reactions occurred between the volatile pyrolysates and CO₂. These reactions result in enhanced CO levels and a reduction in polycyclic aromatic hydrocarbons (PAHs) in pyrolytic oil through the simultaneous reduction of CO₂ and oxidation of volatile pyrolysates. To accelerate the kinetics of these homogeneous reactions, catalytic pyrolysis was performed using Ni-based catalysts. The catalytic effects of The Ni catalyst significantly boosted CO production by promoting homogeneous reactions. The evolution of CO from catalytic pyrolysis under CO₂ conditions was 2.92 times higher than that from double-stage pyrolysis. Thus, these experimental findings underscore the technical advantages of strategically utilising CO₂ in both microalgal biomass cultivation and the thermochemical conversion of microalgal biomass. © 2024 Elsevier B.V.

This study was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government ( MSIT ) (No. NRF-2023R1A2C3003011 ) and Korea Carbon to X R&D Center (2020M3H7A1098295).