Exploring the Catalytic Potential of Oxide Glasses (Ceramics) in the Thermal Decomposition of Fatty Acids

To tackle the critical issue of reducing greenhouse gas emissions, renewable fuels such as biofuels present an attractive alternative to fossil fuels due to their lower toxicity, renewability, biodegradability, and cleaner combustion [1,2]. This study focuses on developing cost-effective and innovative catalysts, specifically glasses (ceramics) derived from the Na₂O-V₂O₅-(Al₂O₃)-P₂O₅-Nb₂O₅ system [3], for the pyrolytic deoxygenation of long-chain fatty acids into alkanes. Stearic acid was selected as a model compound to investigate the thermal decomposition of fatty acids and assess the catalytic performance of oxide glass (ceramic) catalysts, with additional experiments conducted on oleic acid and palmitic acid to extend the study. The tested catalysts varied in V₂O₅ content, ranging up to 70 mol% V₂O₅, with commercially available V₂O₅ used as a standard reference material. Catalytic activity was evaluated using thermogravimetric analysis/differential scanning calorimetry (TG/DSC), while coupled thermogravimetry–infrared spectroscopy (TG-IR) and simultaneous thermal analysis–quadrupole mass spectrometry (STA-QMS) provided comprehensive insights into the decomposition mechanisms. The results indicated that catalysts with a higher V₂O₅ content (≥ 55 mol%) significantly enhanced the thermal decomposition of fatty acids. This study highlights that oxide glasses (ceramics) are efficient catalysts for fatty acid decarboxylation, offering a combination of thermal and chemical stability, cost-effective and straightforward synthesis, and the flexibility to fine-tune catalyst properties through simple compositional adjustments, which is crucial for industrial applications.

This work is supported by the Croatian Science Foundation under projects IP-2018–01–5425 and DOK-2021–02–9665 and partially funded by the European Union – NextGenerationEU.

[1] Mulyatun, M. et al. Catal. Lett. 154, 4837–4855 (2024).

[2] Chen, B., et al., Appl. Catal. B: Environ. 338, 123067 (2023).

[3] Pisk, J. et al. J. Non-Cryst. Solids 626, 122780 (2024).