Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation
This study investigates the temperature-dependent carboxylation of single and mixed biomass-derived phenolic sodium salts with CO₂ via the Kolbe–Schmitt reaction. Reactions were performed at T = 175–225 °C, t = 2 h, and pCO₂ = 30 bar. Five model phenolics; phenol, 2-cresol, guaiacol, catechol, and s...
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Elsevier
2025-06-01
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| Series: | Carbon Capture Science & Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2772656825000818 |
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| author | Omar Mohammad Jude A. Onwudili Qingchun Yuan Robert Evans |
| author_facet | Omar Mohammad Jude A. Onwudili Qingchun Yuan Robert Evans |
| author_sort | Omar Mohammad |
| collection | DOAJ |
| description | This study investigates the temperature-dependent carboxylation of single and mixed biomass-derived phenolic sodium salts with CO₂ via the Kolbe–Schmitt reaction. Reactions were performed at T = 175–225 °C, t = 2 h, and pCO₂ = 30 bar. Five model phenolics; phenol, 2-cresol, guaiacol, catechol, and syringol were examined individually and in mixtures. Characterisation via high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) analysis showed that 2-hydroxybenzoic and dicarboxylic acids were favoured at higher temperatures, while 4-hydroxybenzoic acids prevailed at 175 °C. In mixtures, dicarboxylic acid yields increased significantly, reaching 41.9 % for 2,3-dihydroxyterephthalic acid and 20.5 % for 2-hydroxyisophthalic acid. These dicarboxylic acids possess up to 10-fold higher market value than their monocarboxylic counterparts. Syringic acid synthesis via Kolbe–Schmitt is reported here for the first time, with yields rising to 33.0 % in mixtures versus <2.0 % molar yield when reacted individually. The study also presents the first detailed mechanistic explanation of Brønsted acid–base interactions and temperature-driven selectivity in phenolic salt carboxylation. While previous research suggested that producing phenolics solely from lignin was not viable, this work demonstrates that CO₂ incorporation not only enhances product value but also narrows product distribution and enables broader industrial applicability - ultimately opening new opportunities for potential large-scale, economically viable CO₂ utilisation. |
| format | Article |
| id | doaj-art-98a1f5ff95404ca4abeb9708bb535d23 |
| institution | OA Journals |
| issn | 2772-6568 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Carbon Capture Science & Technology |
| spelling | doaj-art-98a1f5ff95404ca4abeb9708bb535d232025-08-20T02:05:51ZengElsevierCarbon Capture Science & Technology2772-65682025-06-011510044210.1016/j.ccst.2025.100442Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisationOmar Mohammad0Jude A. Onwudili1Qingchun Yuan2Robert Evans3Energy and Bioproducts Research Institute, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United KingdomEnergy and Bioproducts Research Institute, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United Kingdom; Department of Chemical Engineering and Applied Chemistry, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United Kingdom; Corresponding author at: Energy and Bioproducts Research Institute, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United Kingdom.Energy and Bioproducts Research Institute, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United Kingdom; Department of Chemical Engineering and Applied Chemistry, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United KingdomDepartment of Chemical Engineering and Applied Chemistry, Aston University, Aston Triangle, West Midlands, Birmingham B4 7ET, United KingdomThis study investigates the temperature-dependent carboxylation of single and mixed biomass-derived phenolic sodium salts with CO₂ via the Kolbe–Schmitt reaction. Reactions were performed at T = 175–225 °C, t = 2 h, and pCO₂ = 30 bar. Five model phenolics; phenol, 2-cresol, guaiacol, catechol, and syringol were examined individually and in mixtures. Characterisation via high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) analysis showed that 2-hydroxybenzoic and dicarboxylic acids were favoured at higher temperatures, while 4-hydroxybenzoic acids prevailed at 175 °C. In mixtures, dicarboxylic acid yields increased significantly, reaching 41.9 % for 2,3-dihydroxyterephthalic acid and 20.5 % for 2-hydroxyisophthalic acid. These dicarboxylic acids possess up to 10-fold higher market value than their monocarboxylic counterparts. Syringic acid synthesis via Kolbe–Schmitt is reported here for the first time, with yields rising to 33.0 % in mixtures versus <2.0 % molar yield when reacted individually. The study also presents the first detailed mechanistic explanation of Brønsted acid–base interactions and temperature-driven selectivity in phenolic salt carboxylation. While previous research suggested that producing phenolics solely from lignin was not viable, this work demonstrates that CO₂ incorporation not only enhances product value but also narrows product distribution and enables broader industrial applicability - ultimately opening new opportunities for potential large-scale, economically viable CO₂ utilisation.http://www.sciencedirect.com/science/article/pii/S2772656825000818CO2 utilisationHigh-value organic chemicalsHydroxybenzoic acidsDicarboxylic acidsModel biomass-derived phenolicsChemical fixation and reaction mechanisms |
| spellingShingle | Omar Mohammad Jude A. Onwudili Qingchun Yuan Robert Evans Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation Carbon Capture Science & Technology CO2 utilisation High-value organic chemicals Hydroxybenzoic acids Dicarboxylic acids Model biomass-derived phenolics Chemical fixation and reaction mechanisms |
| title | Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation |
| title_full | Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation |
| title_fullStr | Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation |
| title_full_unstemmed | Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation |
| title_short | Optimisation of reaction temperature during carboxylation of single and mixed model bio-derived phenolics as effective route for CO2 utilisation |
| title_sort | optimisation of reaction temperature during carboxylation of single and mixed model bio derived phenolics as effective route for co2 utilisation |
| topic | CO2 utilisation High-value organic chemicals Hydroxybenzoic acids Dicarboxylic acids Model biomass-derived phenolics Chemical fixation and reaction mechanisms |
| url | http://www.sciencedirect.com/science/article/pii/S2772656825000818 |
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