Ferrous and Ferric Ion-Facilitated Dilute Acid Pretreatment of Lignocellulosic Biomass under Anaerobic or Aerobic Conditions: Observations of Fe Valence Interchange and the Role of Fenton Reaction

Journal Article · 01 March 2020 · Molecules

DOI: https://doi.org/10.3390/molecules25061427 · OSTI ID:1606119

Wei, Hui  ^[1]; Wang, Wei ^[1]; Ciesielski, Peter N  ^[1]; Donohoe, Bryon S ^[1]; Zhang, Min ^[1]; Himmel, Michael E ^[1]; Chen, Xiaowen ^[1]; Tucker, Melvin P ^[1]

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1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Ferrous ion co-catalyst enhancement of dilute-acid (DA) pretreatment of biomass is a promising technology for increasing the release of sugars from recalcitrant lignocellulosic biomass. However, due to the reductive status of ferrous ion and its susceptibility to oxidation with exposure to atmosphere, its effective application presumably requires anaerobic aqueous conditions created by nitrogen gas-purging, which adds extra costs. The objective of this study was to assess the effectiveness of oxidative iron ion, (i.e., ferric ion) as a co-catalyst in DA pretreatment of biomass, using an anaerobic chamber to strictly control exposure to oxygen during setup and post-pretreatment analyses. Remarkably, the ferric ions were found to be as efficient as ferrous ions in enhancing sugar release during DA pretreatment of biomass, which may be attributed to the observation that a major portion of the initial ferric ions were converted to ferrous during pretreatment. Furthermore, the detection of hydrogen peroxide in the liquors after DA/Fe ion pretreatment suggests that Fenton reaction chemistry was likely involved in DA/Fe ion pretreatments of biomass, contributing to the observed ferric and ferrous interchanges during pretreatment. These results help define the extent and specification requirements for applying iron ions as co-catalysts in DA pretreatments of biomass.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation and Fuels. Bioenergy Technologies Office (BETO)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1606119
• Report Number(s): NREL-JA-2700-76370; MOLEFW
• Journal Information: Molecules, Vol. 25, Issue 6; ISSN 1420-3049
• Publisher: MDPICopyright Statement
• Country of Publication: United States
• Language: English