Chemically Activated Spruce Organosolv Lignin as a Carbocatalyst for Heterogeneous Oxidative Dehydrogenations in the Liquid Phase

Anna Lenarda, Michele Melchionna, Santeri Aikonen, Tiziano Montini, Paolo Fornasiero, Tao Hu, Michael Hummel, Juho Helaja*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)
54 Downloads (Pure)

Abstract

Activated carbons obtained from organosolv lignin by chemical activation with KOH and oxidized with diluted HNO3 were studied as catalysts for aerobic oxidative dehydrogenation (ODH) reactions. The structure/activity relationship was investigated through multiple techniques revealing the crucial role of oxygen functionality distribution in promoting two mechanistically archetypical ODH probe reactions: (i) the tetrahydroquinoline (THQ) aromatization, which represents ODH triggered by hydride transfer, and (ii) the 2-phenyl indole homocoupling reaction, a model for single-electron transfer-promoted reactions. In particular, the catalytic activity, correlating with oxygen functionality distribution on the basis of X-ray photoelectron spectroscopy and temperature-programmed desorption analysis, was associated with the C═O surface functionalities, as confirmed by blocking experiments with 2,2,2-trifluoroethyl hydrazine. Kinetic profiling tools were employed to assess THQ ODH product inhibition effects on the overall yield of the process as well as the extent of stoichiometric activity of the carbocatalyst. The breadth of the developed catalysts’ applicability was explored through selected relevant ODH reactions.

Original languageEnglish
Pages (from-to)11362-11375
Number of pages14
JournalACS Catalysis
Volume13
Issue number17
Early online date14 Aug 2023
DOIs
Publication statusPublished - 1 Sept 2023
MoE publication typeA1 Journal article-refereed

Keywords

  • carbon materials
  • heterogeneous catalysis
  • lignin
  • organocatalysis
  • oxidative dehydrogenation

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