Continuous catalytic depolymerisation and conversion of industrial kraft lignin into low-molecular-weight aromatics

Abdelaziz, Omar Y.; Li, Kena; Tunå, Per; Hulteberg, Christian

doi:10.1007/s13399-017-0294-2

Cited by 53 publications

(51 citation statements)

References 34 publications

(53 reference statements)

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“…Various lignin depolymerisation and conversion methods have been described in the literature, each approach having its own advantages and limitations. Examples comprise acidcatalysed [11,12], base-catalysed [13,14], thermochemical [15,16], biochemical [1,17], reductive [18,19] and oxidative [20][21][22] lignin depolymerisation. Oxidative depolymerisation, in particular, emerges as a promising route among the deconstruction strategies, as it can produce highly functionalised chemicals under relatively mild operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Oxidative Depolymerisation of Lignosulphonate Lignin into Low-Molecular-Weight Products with Cu–Mn/δ-Al2O3

et al. 2019

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Lignin depolymerisation receives great attention due to the pressing need to find sustainable alternatives to fossil sources for production of fuels and chemicals. In this study, alumina-supported Cu-Mn and Ni-Mo catalysts were tested for oxidative depolymerisation of a technical lignin stream-sodium lignosulphonates-to produce valuable low-molecular-weight aromatics that may be considered for applications in the fuels and chemicals sector. The reactions were performed at elevated temperature and oxygen pressure, and the product mixtures were analysed by size exclusion chromatography, two-dimensional nuclear magnetic resonance spectroscopy and supercritical fluid chromatography mass spectrometry. The best performance was obtained with Cu-Mn/δ-Al 2 O 3 , which was thoroughly characterised before and after use by nitrogen physisorption, scanning electron microscopy, energy dispersive spectroscopy, powder X-ray diffraction, thermal gravimetric analysis, inductively coupled plasma optical emission spectrometry and X-ray photoelectron spectroscopy. Major products identified were vanillin, p-hydroxybenzaldehyde, vanillic acid and p-hydroxybenzoic acid as well as smaller aliphatic aldehydes, acids and lactones.

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Section: Introductionmentioning

confidence: 99%

Oxidative Depolymerisation of Lignosulphonate Lignin into Low-Molecular-Weight Products with Cu–Mn/δ-Al2O3

et al. 2019

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“…The formation of high molecular weight insoluble structures and char is the consequence of the repolymerization that occurs. In order to suppress repolymerization, we have developed a novel continuous flow reactor (CFR) to depolymerize ‘Indulin AT’ (a commericial Kraft lignin that was precipitated from the black liquor of softwood pulp) at 170–240 °C for 1–4 min of residence time by using NaOH as a catalyst [18]. We found that, under the experimental conditions, some of the Indulin AT macromolecules were depolymerized into LMMC.…”

Section: Introductionmentioning

confidence: 99%

Membrane Separation of the Base-Catalyzed Depolymerization of Black Liquor Retentate for Low-Molecular-Mass Compound Production

Al-Rudainy

Sun

et al. 2019

Membranes

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One way of valorizing the lignin waste stream from the pulp and paper industries is depolymerizing it into low-molecular-mass compounds (LMMC). However, a common problem in the depolymerization of Kraft lignin is the low yields of small aromatic molecules obtained. In the present work, the combination of the repeated depolymerization of lignin and the separation of LMMC from depolymerized lignin to upgrade them into value-added chemicals was studied. In so doing, we investigated the possibility of depolymerizing black liquor retentate (BLR). The base-catalyzed depolymerization of BLR was performed using a continuous flow reactor at 170–210 °C, with a 2 min residence time. The results obtained indicate that BLR can be depolymerized effectively under the experimental conditions. Depolymerized lignin LMMC can be successfully separated by a GR95PP membrane, and thus be protected from repolymerization. Through combining membrane filtration with base-catalyzed depolymerization, more than half of the lignin could be depolymerized into LMMC. Around 46 mg/g of lignin monomers (guaiacol, vanillin, acetovanillone, and acetosyringone), which can potentially be upgraded to high-valued chemicals, were produced. On the basis of our results, we suggest use of a recycling Kraft lignin depolymerization and filtration process for maximizing the production of LMMC under mild alkaline conditions.

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“…All the investigations have been performed systematically using the same reference conditions (350°C, 25 MPa, 5.5 wt% lignin, 4 wt% phenol, and 1.6 wt% potassium carbonate). The influence of temperature was investigated in five steps from 290 to 370°C [19] and showed that the yield of bio-oil decreased slightly when the temperature was increased. The yield of water-soluble organics (WSO) as well as the char on catalyst increased slightly.…”

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Hydrothermal liquefaction of kraft lignin in sub-critical water: the influence of the sodium and potassium fraction

Belkheiri

Andersson

Mattsson

et al. 2018

Biomass Conv. Bioref.

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As a part of developing a hydrothermal liquefaction (HTL) process to valorise lignin, it is important to consider integration possibilities with existing infrastructures in order to obtain an overall positive economic impact. One obvious example is to integrate the HTL process with the kraft pulp mill: transport and storage costs is reduced, the temperature levels on process streams can be matched (energy integration) and the recovery/use of alkali can be made efficient. In this study, softwood kraft lignin was depolymerised using sub-critical water (623 K; 25 MPa) in a continuous, small pilot unit with a flow rate of 2 kg/h. ZrO 2 , K 2 CO 3 /KOH and Na 2 CO 3 /NaOH were used as catalytic system, and phenol as the capping agent. The influence of the ratio between sodium and potassium in the feed on the yield and composition of the product stream was investigated. The results showed that bio-oil, water-soluble organics (WSO) and char yields were not remarkably influenced by shifting the catalytic system from potassium to sodium. Moreover, the yields of most phenolic compounds did not change significantly when the sodium fraction was varied in the feed. The amounts of suspended solids in the bio-oil produced showed, however, a diminishing trend, (decrease from 10.8 to 3.8%) when the sodium fraction was increased in the feed, whilst the opposite trend was observed for the heavy oil, which increased from 24.6 to 37.6%.

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Continuous catalytic depolymerisation and conversion of industrial kraft lignin into low-molecular-weight aromatics

Cited by 53 publications

References 34 publications

Oxidative Depolymerisation of Lignosulphonate Lignin into Low-Molecular-Weight Products with Cu–Mn/δ-Al2O3

Oxidative Depolymerisation of Lignosulphonate Lignin into Low-Molecular-Weight Products with Cu–Mn/δ-Al2O3

Membrane Separation of the Base-Catalyzed Depolymerization of Black Liquor Retentate for Low-Molecular-Mass Compound Production

Hydrothermal liquefaction of kraft lignin in sub-critical water: the influence of the sodium and potassium fraction

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