Optimised pyrolysis strategies for energy-dense bio-oil from Chlorella sp

Ferreira, Gabriela F., Hayward, James S., Nelson, Matthew, Slocombe, Daniel R. ORCID: https://orcid.org/0000-0003-3590-6075 and Bartley, Jonathan K. ORCID: https://orcid.org/0000-0003-4640-541X 2026. Optimised pyrolysis strategies for energy-dense bio-oil from Chlorella sp. Bioresource Technology 441 , 133628. 10.1016/j.biortech.2025.133628

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Abstract

Microalgae are promising feedstocks for sustainable biofuels due to rapid growth, CO2 fixation, and non-reliance on arable land. This study investigates the pyrolysis of Chlorella sp. under non-catalytic, catalytic, and microwave-assisted configurations to optimise bio-oil composition and energy density. Response surface methodology identified optimal conditions at 550 °C and 60 °C/min, yielding 43 wt% bio-oil. Catalytic pyrolysis with HZSM-5 and Na2CO3 improved deoxygenation and increased higher heating value (HHV) to 30.8 MJ/kg. Microwave-assisted pyrolysis at 80 W (∼80 W/g for 1 g sample) produced the best bio-oil, with 68.3 % C, 16.1 % O, and HHV of 33.4 MJ/kg. Carbon-rich biochar (∼80 wt% C) was also obtained, suitable for soil amendment or activation. Catalyst-dependent gas profiles were observed, with Na2CO3). Yielding 24.7 vol% H2. These results highlight the potential of tuning pyrolysis configuration to upgrade algal biomass without post-treatment. The study supports the development of drop-in microalgal biofuels and reinforces their role in circular, carbon–neutral energy systems.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Engineering Schools > Chemistry Research Institutes & Centres > Cardiff Catalysis Institute (CCI)
Publisher:	Elsevier
ISSN:	0960-8524
Date of First Compliant Deposit:	24 November 2025
Date of Acceptance:	8 November 2025
Last Modified:	24 Nov 2025 16:15
URI:	https://orca.cardiff.ac.uk/id/eprint/182602

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