Lignin alkaline oxidation using reversibly-soluble bases. Issue 22 (31st October 2022)

• Record Type: Journal Article
• Authors: Kruger, Jacob S.; Dreiling, Reagan J.; Wilcox, Daniel G.; Ringsby, Arik J.; Noon, Katherine L.; Amador, Camille K.; Brandner, David G.; Ramirez, Kelsey J.; Haugen, Stefan J.; Klein, Bruno C.; Davis, Ryan; Hanes, Rebecca J.; Happs, Renee M.; Cleveland, Nicholas S.; Christensen, Earl D.; Miscall, Joel; Beckham, Gregg T.
• Is Part Of: Green chemistry. Volume 24:Issue 22(2022)
• Page Start: 8733
• Page End: 8741
• Publication Date: 2022-10-31
• Subjects: Environmental chemistry -- Industrial applications -- Periodicals; Environmental management -- Periodicals; 660
• DOI: 10.1039/d2gc03333j
• Languages: English
• ISSNs: 1463-9262

Abstract

Abstract : When excess base is required to drive desired reactions, such as in lignin alkaline oxidation, Sr(OH)2 can offer a reversibly-soluble alternative to NaOH that allows simple recycle of the excess base with concomitant cost and environmental benefits. Abstract : Lignin valorization approaches, which are critical to biorefining, often involve depolymerization to aromatic monomers. Alkaline oxidation has long held promise as a lignin depolymerization strategy, but requires high concentrations of base, typically NaOH, much of which must be neutralized to recover lignin-derived aromatic monomers. This consumption of base and associated waste generation incurs high cost and negative environmental impacts. In this work, we demonstrate that Sr(OH)2 and Ba(OH)2 perform comparably to NaOH in terms of total aromatic monomer yields in the aqueous aerobic alkaline depolymerization of corn stover lignin, and that up to 90% of these reversibly-soluble bases can be recovered via precipitation and filtration. Process modeling suggests that the use of Sr(OH)2 could reduce the cost of alkaline oxidation by 20–60% compared to NaOH, depending on lignin loading. In contrast, the energy required to regenerate the Sr largely offsets potential improvements in sustainability over Na-promoted alkaline oxidation, though the sustainability comparison is likely sensitive to the lignin composition and could be improved by further optimization of the regeneration step.