Preparation and characterization of lignin-derived carbon aerogels

Piia Jõul; Oliver Järvik; Heidi Lees; Urve Kallavus; Mihkel Koel; Tiit Lukk

doi:10.3389/fchem.2023.1326454

Preparation and characterization of lignin-derived carbon aerogels

Front Chem. 2024 Jan 8:11:1326454. doi: 10.3389/fchem.2023.1326454. eCollection 2023.

Authors

Piia Jõul¹, Oliver Järvik², Heidi Lees², Urve Kallavus³, Mihkel Koel¹, Tiit Lukk¹

Affiliations

¹ Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.
² Department of Energy Technology, Tallinn University of Technology, Tallinn, Estonia.
³ Department of Mechanical and Industrial Engineering, Tallinn University of Technology, Tallinn, Estonia.

Abstract

Lignin is considered a valuable renewable resource for building new chemicals and materials, particularly resins and polymers. The aromatic nature of lignin suggests a synthetic route for synthesizing organic aerogels (AGs) similar to the aqueous polycondensation of resorcinol with formaldehyde (FA). The structure and reactivity of lignin largely depend on the severity of the isolation method used, which challenges the development of new organic and carbon materials. Resorcinol aerogels are considered a source of porous carbon material, while lignin-based aerogels also possess great potential for the development of carbon materials, having a high carbon yield with a high specific surface area and microporosity. In the present study, the birch hydrolysis lignin and organosolv lignin extracted from pine were used to prepare AGs with formaldehyde, with the addition of 5-methylresorcinol in the range of 75%-25%, yielding monolithic mesoporous aerogels with a relatively high specific surface area of up to 343.4 m²/g. The obtained lignin-based AGs were further used as raw materials for the preparation of porous carbon aerogels (CAs) under well-controlled pyrolysis conditions with the morphology, especially porosity and the specific surface area, being dependent on the origin of lignin and its content in the starting material.

Keywords: aerogels; carbon aerogels; lignin; pyrolysis; resorcinol–formaldehyde gels; supercritical drying.

Grants and funding

The authors declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by ERDF and Estonian Research Council via project RESTA11 and via Grant PRG1784. The authors declare that this study received chemicals from Fibenol OÜ and VKG AS. The funders were not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication. This publication is based upon work from COST Action “Advanced Engineering of aeroGels for Environment and Life Sciences” (AERoGELS, ref. CA18125), supported by COST (European Cooperation in Science and Technology).