Formation, Molecular Structure, and Morphology of Humins in Biomass Conversion: Influence of Feedstock and Processing Conditions

Ilona van Zandvoort, Yuehu Wang, Carolus B. Rasrendra, Ernst R. H. van Eck, Pieter C. A. Bruijnincx, Hero J. Heeres, Bert M. Weckhuysen

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Neither the routes through which humin byproducts are formed, nor their molecular structure have yet been unequivocally established. A better understanding of the formation and physicochemical properties of humins, however, would aid in making biomass conversion processes more efficient. Here, an extensive multiple-technique-based study of the formation, molecular structure, and morphology of humins is presented as a function of sugar feed, the presence of additives (e.g., 1,2,4-trihydroxybenzene), and the applied processing conditions. Elemental analyses indicate that humins are formed through a dehydration pathway, with humin formation and levulinic acid yields strongly depending on the processing parameters. The addition of implied intermediates to the feedstocks showed that furan and phenol compounds formed during the acid-catalyzed dehydration of sugars are indeed included in the humin structure. IR spectra, sheared sum projections of solid-state 2DPASS (CNMR)-C-13 spectra, and pyrolysis GC-MS data indicate that humins consist of a furan-rich polymer network containing different oxygen functional groups. The structure is furthermore found to strongly depend on the type of feedstock. A model for the molecular structure of humins is proposed based on the data presented.
Original languageEnglish
Pages (from-to)1745-1758
Number of pages14
JournalChemSusChem
Volume6
Issue number9
DOIs
Publication statusPublished - Sept 2013

Keywords

  • Biomass
  • Carbohydrates
  • Furans
  • Reaction mechanisms
  • Structure elucidation

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