Solvothermal liquefaction of alkali lignin to obtain a high yield of aromatic monomers while suppressing solvent consumption

The high content of oxygen in the lignin polymer and the prevalence of phenolic functional groups make the conversion of lignin to fuels and value-added products with well-defined chemical properties challenging. The lignin-to-liquid process using a water/formic acid reaction medium has been shown to convert the lignin polymer to monomers with a molecular weight range of 300–600 Da. The bio-oil comprises a complex mixture of monomeric phenols, aromatics, and aliphatic hydrocarbons with a high H/C and low O/C ratio. This study investigates the effect of the stirring rate, level of loading, and catalyst at 305 and 350 °C in a 5 L pilot scale reactor. The oil yields are found to be highest for experiments conducted using the maximum stirring rate, maximum level of loading, and Ru/Al2O3 catalyst with yields of more than 69 wt % on lignin intake. Goethite as a catalyst does not show good conversion efficiency at either reaction temperatures. The carbon recovery is highest for products produced at 305 °C. Furthermore, results from solid phase extraction on a DSC-CN solid phase show that 65–92 wt % the bio-oils can be recovered as fractions separated based on polarity.

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“…The complete lignin conversion resulted in high aromatic monomer yields of 36.7 wt % on a dry ash-free lignin basis. 27…”

Section: Introductionmentioning

confidence: 99%

Effect of Reaction Conditions on Catalytic and Noncatalytic Lignin Solvolysis in Water Media Investigated for a 5 L Reactor

2019

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“…Given the moderate oil yield in the current system, we tried our best to improve it. Although no significant breakthrough has been achieved so far, strategies like adding capping agents (e.g., formaldehyde 10 or acetaldehyde 11 ) to stabilise lignin radical have been reported recently to enhance lignin depolymerisation. Despite the product yield, further analysis of the product selectivity was explored to gain a deeper insight.…”

Section: Resultsmentioning

confidence: 99%

Is oxidation–reduction a real robust strategy for lignin conversion? A comparative study on lignin and model compounds

et al. 2019

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“… 9 , 11 Other petroleum replacing applications, heavily depending on lignin chemistry, include utilization in hydrophobic composites, 12 , 13 for lubricant production, 14 , 15 carbon fiber production, 16 , 17 nanoparticles, 18 adsorption purposes in aqueous remediation systems, 19 , 20 or production of low-molecular-weight aromatics and hydrocarbons. 21 , 22 Despite the fact that lignin chemistry will heavily influence its suitability for a specific application, there is nowadays still a lot of need for strictly connecting isolation process parameters to chemical features of the extracted lignin and the abundance of specific structural motifs and the resulting consequences for suitable high-value applications. The current work thus sets out to investigate the application of a promising mode of extraction, namely, the novel organosolv/steam-explosion method, 23 which combines the benefits of a catalytically active solvent allowing the dissolution of hydrolyzed lignin with the shear force of depressurization made more effective by solvent-softening of cell–cell adhesion.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Organosolv Birch Lignins: Toward Application-Specific Lignin Production

et al. 2021

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Organosolv pretreatment represents one of the most promising biomass valorization strategies for renewable carbon-based products; meanwhile, there is an overall lack of holistic approach to how extraction conditions affect the suitable end-usages. In this context, lignin extracted from silver birch ( Betula pendula L.) by a novel hybrid organosolv/steam-explosion treatment at varying process conditions (EtOH %; time; catalyst %) was analyzed by quantitative NMR ( 1 H– 13 C HSQC; 13 C NMR; 31 P NMR), gel permeation chromatography, Fourier transform infrared (FT-IR), Pyr-gas chromatography–mass spectroscopy (GC/MS), and thermogravimetric analysis, and the physicochemical characteristics of the lignins were discussed regarding their potential usages. Characteristic lignin interunit bonding motifs, such as β- O -4′, β-β′, and β-5′, were found to dominate in the extracted lignins, with their abundance varying with treatment conditions. Low-molecular-weight lignins with fairly unaltered characteristics were generated via extraction with the highest ethanol content potentially suitable for subsequent production of free phenolics. Furthermore, β-β′ and β-5′ structures were predominant at higher acid catalyst contents and prolonged treatment times. Higher acid catalyst content led to oxidation and ethoxylation of side-chains, with the concomitant gradual disappearance of p -hydroxycinnamyl alcohol and cinnamaldehyde. This said, the increasing application of acid generated a broad set of lignin characteristics with potential applications such as antioxidants, carbon fiber, nanoparticles, and water remediation purposes.

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Solvothermal liquefaction of alkali lignin to obtain a high yield of aromatic monomers while suppressing solvent consumption

Abstract: The use of formic acid leads to the complete decomposition of alkali lignin and affords high-yield aromatic monomers, while at the same time suppress consumption of solvent used for the lignin conversion.

Cited by 56 publications

References 70 publications

Effect of Reaction Conditions on Catalytic and Noncatalytic Lignin Solvolysis in Water Media Investigated for a 5 L Reactor

Effect of Reaction Conditions on Catalytic and Noncatalytic Lignin Solvolysis in Water Media Investigated for a 5 L Reactor

Is oxidation–reduction a real robust strategy for lignin conversion? A comparative study on lignin and model compounds

Characterization of Organosolv Birch Lignins: Toward Application-Specific Lignin Production

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