Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)

Microalgae's high photosynthetic efficiency and CO2 sequestration capability makes it an attractive feedstock for biofuels and value-added compounds. Zeolite Y is widely used in biomass conversion due to its affordability and high catalytic activity, but its limited acidity and susceptibility t...

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Main Authors: A. Aliyu, J.G.M. Lee, A.P. Harvey
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Next Sustainability
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Online Access:http://www.sciencedirect.com/science/article/pii/S2949823625000443
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author A. Aliyu
J.G.M. Lee
A.P. Harvey
author_facet A. Aliyu
J.G.M. Lee
A.P. Harvey
author_sort A. Aliyu
collection DOAJ
description Microalgae's high photosynthetic efficiency and CO2 sequestration capability makes it an attractive feedstock for biofuels and value-added compounds. Zeolite Y is widely used in biomass conversion due to its affordability and high catalytic activity, but its limited acidity and susceptibility to coking present challenges. This study investigates whether sulfated zirconia, with its superacidic properties, can serve as an alternative catalyst to zeolite Y for improving bio-oil quality in Chlorella vulgaris pyrolysis. Sulfated zirconia catalysts with zirconium-to-sulfate ratios of 1:1 and 1:6 (wt/wt) were synthesized using a solvent-free method and evaluated alongside zeolite Y using Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GCMS) and isothermal pyrolysis at 400, 500, and 600°C. Py-GC/MS analysis revealed that zeolite Y, sulfated zirconia (1:1), and sulfated zirconia (1:6) increased aromatic content by 227 %, 69 %, and 50 %, respectively, than the non-catalytic process. Additionally, sulfated zirconia at 400 °C produced bio-oil with a 29.9 % higher heating value (HHV) than the non-catalytic process. This is comparable to the highest HHV of 37.8 % achieved with zeolite Y at 500 °C. These results suggest that sulfated zirconia catalysts effectively enhance aromatic production while suppressing nitrogen-containing and acidic compounds, making them a viable alternative to zeolite Y in Chlorella vulgaris pyrolysis. Furthermore, a comparison of catalytic and non-catalytic reaction mechanisms highlights the significant influence of acid site distribution on product selectivity, demonstrating the potential of sulfated zirconia in optimizing biofuel composition.
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spelling doaj-art-747baa846d09422a948cb489a35f3b212025-08-20T02:34:35ZengElsevierNext Sustainability2949-82362025-01-01510014110.1016/j.nxsust.2025.100141Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)A. Aliyu0J.G.M. Lee1A.P. Harvey2School of Engineering, Newcastle University, United Kingdom; Department of Chemical Engineering, Ahmadu Bello University, Zaria, Nigeria; Africa Centre of Excellence on New Pedagogies in Engineering Education, Ahmadu Bello University, Zaria, Nigeria; Corresponding author at: School of Engineering, Newcastle University, United Kingdom.School of Engineering, Newcastle University, United KingdomSchool of Engineering, Newcastle University, United KingdomMicroalgae's high photosynthetic efficiency and CO2 sequestration capability makes it an attractive feedstock for biofuels and value-added compounds. Zeolite Y is widely used in biomass conversion due to its affordability and high catalytic activity, but its limited acidity and susceptibility to coking present challenges. This study investigates whether sulfated zirconia, with its superacidic properties, can serve as an alternative catalyst to zeolite Y for improving bio-oil quality in Chlorella vulgaris pyrolysis. Sulfated zirconia catalysts with zirconium-to-sulfate ratios of 1:1 and 1:6 (wt/wt) were synthesized using a solvent-free method and evaluated alongside zeolite Y using Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GCMS) and isothermal pyrolysis at 400, 500, and 600°C. Py-GC/MS analysis revealed that zeolite Y, sulfated zirconia (1:1), and sulfated zirconia (1:6) increased aromatic content by 227 %, 69 %, and 50 %, respectively, than the non-catalytic process. Additionally, sulfated zirconia at 400 °C produced bio-oil with a 29.9 % higher heating value (HHV) than the non-catalytic process. This is comparable to the highest HHV of 37.8 % achieved with zeolite Y at 500 °C. These results suggest that sulfated zirconia catalysts effectively enhance aromatic production while suppressing nitrogen-containing and acidic compounds, making them a viable alternative to zeolite Y in Chlorella vulgaris pyrolysis. Furthermore, a comparison of catalytic and non-catalytic reaction mechanisms highlights the significant influence of acid site distribution on product selectivity, demonstrating the potential of sulfated zirconia in optimizing biofuel composition.http://www.sciencedirect.com/science/article/pii/S2949823625000443MicroalgaeChlorella vulgarisZeoilite YSulfated zirconiaThermogravimetric analysisPy-GCMS
spellingShingle A. Aliyu
J.G.M. Lee
A.P. Harvey
Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)
Next Sustainability
Microalgae
Chlorella vulgaris
Zeoilite Y
Sulfated zirconia
Thermogravimetric analysis
Py-GCMS
title Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)
title_full Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)
title_fullStr Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)
title_full_unstemmed Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)
title_short Microalgae for biofuel: Comparing the performance of solvent-free sulfated zirconia catalysts and zeolite Y for the catalytic pyrolysis of freshwater microalgae (Chlorella vulgaris)
title_sort microalgae for biofuel comparing the performance of solvent free sulfated zirconia catalysts and zeolite y for the catalytic pyrolysis of freshwater microalgae chlorella vulgaris
topic Microalgae
Chlorella vulgaris
Zeoilite Y
Sulfated zirconia
Thermogravimetric analysis
Py-GCMS
url http://www.sciencedirect.com/science/article/pii/S2949823625000443
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