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ARTICLE

Preliminary Study: Furfural Production from Oat Husks via Phosphorus-Containing Catalysts Catalyzed Hydrothermal Pretreatment in the Context of Biorefinery

Prans Brazdausks^*, Maris Puke, Guntis Sosins

Biorefinery Laboratory, Latvian State Institute of Wood Chemistry, Riga, LV-1001, Latvia

* Corresponding Author: Prans Brazdausks. Email:

(This article belongs to the Special Issue: Advances in Biorefinery Technologies and Products – 2024)

Journal of Renewable Materials 2025, 13(4), 719-730. https://doi.org/10.32604/jrm.2025.057944

Received 31 August 2024; Accepted 07 January 2025; Issue published 21 April 2025

Abstract

Oat husks, a byproduct of oat milling operations with limited economic value, present a promising feedstock for biorefinery processes due to their chemical composition. This study investigates the conversion of C5 carbohydrates in oat husks into furfural through hydrothermal pretreatment using various phosphate-based catalysts, including H₃PO₄, NH₄H₂PO₄, NaH₂PO₄, KH₂PO₄, K₂HPO₄ and K₃PO₄ as catalyst. The catalysts’ effectiveness in promoting furfural production was evaluated under identical hydrothermal conditions (treatment time for 60 min at a constant temperature of 170°C and a catalyst amount). Continuous water steam was used to strip furfural from the reaction zone and minimize its degradation. Results indicated that H₃PO₄ was the most effective catalyst, achieving a furfural yield of 13.99 wt.%, which corresponds to approximately 57% of the theoretical yield. NH₄H₂PO₄ also showed moderate effectiveness, while sodium and potassium phosphate salts were significantly less effective. A scanning electron microscope analysis shows that catalysts with lower pH may disrupt the oat husks external layer thus providing a higher C5 carbohydrates conversion rate into furfural. The chemical complexity of oat husk contributes to side reactions between its carbohydrates and lignin during the hydrothermal treatment. This results in an increase in acid-insoluble lignin and inorganic matter in the oat husk lignocellulosic residue, which can reduce the effectiveness of further cellulose saccharification by enzymatic hydrolysis.

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