{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T03:26:14Z","timestamp":1775705174197,"version":"3.50.1"},"reference-count":110,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2021,7,29]],"date-time":"2021-07-29T00:00:00Z","timestamp":1627516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Lignin is the second most abundant component, next to cellulose, in lignocellulosic biomass. Large amounts of this polymer are produced annually in the pulp and paper industries as a coproduct from the cooking process\u2014most of it burned as fuel for energy. Strategies regarding lignin valorization have attracted significant attention over the recent decades due to lignin\u2019s aromatic structure. Oxidative depolymerization allows converting lignin into added-value compounds, as phenolic monomers and\/or dicarboxylic acids, which could be an excellent alternative to aromatic petrochemicals. However, the major challenge is to enhance the reactivity and selectivity of the lignin structure towards depolymerization and prevent condensation reactions. This review includes a comprehensive overview of the main contributions of lignin valorization through oxidative depolymerization to produce added-value compounds (vanillin and syringaldehyde) that have been developed over the recent decades in the LSRE group. An evaluation of the valuable products obtained from oxidation in an alkaline medium with oxygen of lignins and liquors from different sources and delignification processes is also provided. A review of C4 dicarboxylic acids obtained from lignin oxidation is also included, emphasizing catalytic conversion by O2 or H2O2 oxidation.<\/jats:p>","DOI":"10.3390\/molecules26154602","type":"journal-article","created":{"date-parts":[[2021,7,29]],"date-time":"2021-07-29T21:21:21Z","timestamp":1627593681000},"page":"4602","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":51,"title":["Added-Value Chemicals from Lignin Oxidation"],"prefix":"10.3390","volume":"26","author":[{"given":"Carina A. Esteves","family":"Costa","sequence":"first","affiliation":[{"name":"Laboratory of Separation and Reaction Engineering\u2014Laboratory of Catalysis and Materials (LSRE-LCM), Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8542-8732","authenticated-orcid":false,"given":"Carlos A.","family":"Vega-Aguilar","sequence":"additional","affiliation":[{"name":"Laboratory of Separation and Reaction Engineering\u2014Laboratory of Catalysis and Materials (LSRE-LCM), Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"},{"name":"Centro de Investiga\u00e7\u00e3o de Montanha\u2212CIMO, Instituto Polit\u00e9cnico de Bragan\u00e7a, Campus de Santa Apol\u00f3nia, 5300-253 Bragan\u00e7a, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0715-4761","authenticated-orcid":false,"given":"Al\u00edrio E.","family":"Rodrigues","sequence":"additional","affiliation":[{"name":"Laboratory of Separation and Reaction Engineering\u2014Laboratory of Catalysis and Materials (LSRE-LCM), Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4200","DOI":"10.1039\/C7GC01479A","article-title":"Lignin transformations for high value applications: Towards targeted modifications using green chemistry","volume":"19","author":"Gillet","year":"2017","journal-title":"Green Chem."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Rodrigues, A.E., Pinto, P.C.d.R., Barreiro, M.F., da Costa, C.A.E., da Mota, M.I.F., and Fernandes, I. 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