Effect of pH on Kraft Lignin Depolymerisation in Subcritical Water

Belkheiri, Tallal; Mattsson, Cecilia; Andersson, Sven-Ingvar; Olausson, Lars; Åmand, Lars-Erik; Theliander, Hans; Vamling, Lennart

doi:10.1021/acs.energyfuels.6b00462

Cited by 35 publications

(41 citation statements)

References 32 publications

(101 reference statements)

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“…The samples of bio-oil investigated in this work came from a process in which LignoBoost Kraft softwood lignin was converted into bio-oil in a continuous reactor operating at subcritical conditions in water; the samples are characterised elsewhere [20][21][22][23][24]. In these experiments, the reactor temperature and pressure were kept at 350°C and 25 MPa, respectively.…”

Section: Production Of the Bio-oilmentioning

confidence: 99%

“…The flow rate of the feed was 2 kg/h, the recycle-to-feed ratio was 4 and the steady-state period for sampling was 1 h and 20 min. Further details of the apparatus and procedure related to the production of lignin-derived bio-oil can be found in previous work by Nguyen et al [21,22] and Belkheiri et al [23,24].…”

Section: Production Of the Bio-oilmentioning

confidence: 99%

“…substituted with hydroxyl, methoxyl and alkyl groups, and only a small amount of carboxylic acids/aldehydes groups are to be found. It was shown that these active organic functional groups combine with residues of ash and influence the stability of the HTL bio-oil negatively [20][21][22][23][24]. The complexity of the chemical composition of bio-oil has meant that studies on the ageing of HTL bio-oil at a molecular level have rarely been published, particularly with respect to the ageing of lignin derived HTL bio-oil.…”

Section: Introductionmentioning

confidence: 99%

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Thermal stability of low and high Mw fractions of bio-oil derived from lignin conversion in subcritical water

Lyckeskog

Mattsson

Olausson

et al. 2016

Biomass Conv. Bioref.

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The thermal stability of bio-oil influences its application in industry and is, therefore, a very important factor that must be taken into consideration. In this study, the stability of low and high molecular weight (Mw) fractions of bio-oil obtained from the hydrothermal liquefaction (HTL) of lignin in subcritical water was studied at an elevated temperature (80°C) for a period of 1 h, 1 day and 1 week. The changes in molecular weight (gel permeation chromatography (GPC)) and chemical composition (gas chromatography-mass spectrometry (GC-MS) and 2D heteronuclear single quantum correlation (HSQC) NMR (18.8 T, DMSO-d 6 )) of low and high Mw fractions of the HTL bio-oil (i.e. light oil (LO) and heavy oil (HO)) were evaluated before and after ageing. It was found that only a slight formation of high Mw insoluble structures was obtained during ageing at elevated temperature for 1 week: 0.5% for the LO and 3.1% for the HO. These higher Mw moieties might be formed from different polymerisation/ condensation reactions of the reactive compounds (i.e. anisoles, guaiacols, phenols, methylene (-CH 2 -) groups in phenolic dimers and xanthene). The high Mw insolubles in both the LO and the HO were analysed for structural composition using 2D HSQC NMR to obtain a better understanding of the changes in the composition of bio-oil fractions during the accelerated ageing process. In addition, a chemical shift database in DMSO-d 6 was analysed for a subset of phenolic model compounds to simplify the interpretation of the 2D HSQC NMR spectra.

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Section: Production Of the Bio-oilmentioning

confidence: 99%

Section: Production Of the Bio-oilmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermal stability of low and high Mw fractions of bio-oil derived from lignin conversion in subcritical water

Lyckeskog

Mattsson

Olausson

et al. 2016

Biomass Conv. Bioref.

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“…As the NCW process is intended for bulk production, continuous reactors have a clear advantage for upscaling. Belkheiri et al used a hybrid plug flow reactor with internal recirculation, meaning that a pump is used instead of the stirrer in a continuous stirred tank reactor (CSTR) (Belkheiri et al, ). This adds additional flexibility, because different recirculation ratios (RRs) can be used, and the plug flow reactor (PFR)/recycle design is best for maximizing targeted intermediate reaction products by finding an optimal RR (Levenspiel, ).…”

Section: Methodsmentioning

confidence: 99%

“…Alkylation and condensation reactions may also occur in competition with these main reactions. To moderate these condensation reactions, end‐capping agents or hydrogen donors may be added and have proven effective in reducing solids formation (Belkheiri et al, ).…”

Section: Introductionmentioning

confidence: 99%

Technoeconomic assessment of hydrothermal liquefaction oil from lignin with catalytic upgrading for renewable fuel and chemical production

Funkenbusch

Mullins

Vamling

et al. 2018

WIREs Energy & Environment

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Lignin is a readily available by-product of the Kraft pulping process, and may be processed via hydrothermal liquefaction (HTL) to produce a bio-oil suitable for cofeeding into a petroleum refinery hydrotreatment unit. HTL of lignin is performed in near-critical water and, in addition to the bio-oil, produces an aqueous organic and solid char phase. The aqueous organics are primarily phenolics, which may be converted into valuable coproducts via liquid-liquid extraction and hydrotreatment to benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds. Three technological scenarios were developed: a current technology case, a state-of-the-art research case, and an optimal case based on product targets provided by refiners. For a large Kraft pulp mill (400 metric tons/day of dry lignin), a renewable fuel production of 65-70 million L/year, with capital costs of $114-125 million and a final per liter cost of $0.41-0.44 were estimated. The BTEX coproduct yield ranged from 16.8-18.0 million L/year. An economic analysis of the process revealed that the hydrotreatment steps have the highest installed capital costs, while the liquid-liquid extraction process is the largest operating cost. Based on these results, the minimum selling price (MSP) of the biofuel is between $3.52 and $3.86/gallon, and the MSP of BTEX is between $1.65 and $2.00 per liter. With current technology, coproduction of BTEX does not offset the cost of biofuel production. Improved technology to further lower bio-oil oxygen content and decrease both capital and operating costs are needed to make HTL-based fuels competitive with fossil fuel-based options.

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Attapulgite‐supported magnetic dual acid–base catalyst for the catalytic conversion of lignin to phenolic monomers

Zhang

Zhao

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND Research on the catalytic conversion of lignin into value‐added chemicals has grown rapidly on account of the importance of lignin in the biorefinery. There is thus a need to investigate novel technologies to depolymerize lignin in the absence of hydrogen gas and noble metal catalysts. This study developed a cheap and recyclable catalyst via a facile process involving impregnation and calcination for the conversion of lignin to value‐added phenolic monomers. RESULTS Acid sites, basic sites and magnetic components were successfully incorporated into attapulgite. The resulting catalyst displayed high catalytic activity for lignin conversion to phenolic monomers, which resulted in 10.9% total monomers yield at 250 °C for 3 h with a catalyst loading of 50% and a solvent–solid ratio of 20:1 in 50% C2H5OH. The total monomers yield decreased observably after eight successive reaction runs. After being calcined at 600 °C for 3 h, the recovered catalyst provided a total monomers yield of 6.74% in the ninth reaction run. CONCLUSION A novel catalyst was successfully prepared by incorporation of acid sites, basic sites and magnetic properties using natural attapulgite clay as a precursor via a simple and inexpensive process. The resulting catalyst could depolymerize lignin efficaciously. The reusability of the catalyst was barely satisfactory, however, the activity could be partly recovered by simple calcination. © 2018 Society of Chemical Industry

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Effect of pH on Kraft Lignin Depolymerisation in Subcritical Water

Cited by 35 publications

References 32 publications

Thermal stability of low and high Mw fractions of bio-oil derived from lignin conversion in subcritical water

Thermal stability of low and high Mw fractions of bio-oil derived from lignin conversion in subcritical water

Technoeconomic assessment of hydrothermal liquefaction oil from lignin with catalytic upgrading for renewable fuel and chemical production

Attapulgite‐supported magnetic dual acid–base catalyst for the catalytic conversion of lignin to phenolic monomers

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