Structural and Morphological Changes in Kraft Lignin during Hydrothermal Carbonization

Wikberg, Hanne; Ohra-aho, Taina; Pileidis, Filoklis D.; Titirici, Maria‐Magdalena

doi:10.1021/acssuschemeng.5b00925

Cited by 144 publications

(79 citation statements)

References 34 publications

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“…The results demonstrated that solvents with poorer polarity benefited the improvement of char yield and carbon recovery. Char yield and carbon recovery of E‐260 from supercritical ethanol were 48.0 % and 57.9 %, respectively, higher than that of W‐260 (41.1 % and 46.9 %) from subcritical water, while the addition of H 2 SO 4 and NaOH remarkably improved the production of biochars . All solvothermal carbon from lignin had small or even no BET surface area (0.4‐2.8 m 2 g −1 for alcohothermal carbon), but certain content of oxygen‐containing functional groups (Figure ).…”

Section: Resultsmentioning

confidence: 98%

“…Nowadays, the preparation of carbon‐based functional catalysts from renewable bioresources such as waste lignin through hydrothermal route has received increasing attentions . Hydrothermal carbonization of lignin produces biochars with lower BET surface, thermally stable char structure and irregular or melted morphology, and has many advantages such as high oxygen functionality of the obtained chars . Solvents play critical role in the carbonization and other solvothermal conversion of lignin .…”

Section: Introductionmentioning

confidence: 99%

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The Formation of Char, Gaseous and Liquid Products during Lignin Carbonization in Super‐ and Subcritical Solvents

Luo

Yang

et al. 2017

ChemistrySelect

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The carbonization of lignin was performed using different solvents including ethanol, water and 50 vol% ethanol/water mixture under super-and subcritical conditions at 260 8C. The chars from lignin carbonization in supercritical ethanol provided low O/C ratio (0.09-0.14) and considerable content of surface oxygen-containing group (0.18-0.32 mmol g À1 ). Supercritical ethanol substantially participated in lignin carbonization, while the activity of ethanol was also influenced by the chemical structure of lignin. High carbon recovery of 103.8 % for chars was obtained from dealkaline lignin with guaiacyl characteristics, accompained with the production of H 2 and high valuable C 6 -C 10 esters. IntroductionNowadays, the preparation of carbon-based functional catalysts from renewable bioresources such as waste lignin through hydrothermal route has received increasing attentions. [1] Hydrothermal carbonization of lignin produces biochars with lower BET surface, [2] thermally stable char structure [3] and irregular [4] or melted morphology, [3] and has many advantages such as high oxygen functionality of the obtained chars. [5] Solvents play critical role in the carbonization and other solvothermal conversion of lignin. [6] The hydrothermal carbonization of lignin had two possible mechanisms: 1) lignin was firstly hydrolyzed or degraded to phenols and other water-soluble fragments, and then recondensed to form phenol-type chars, which we called as "homogeneous-like" route; 2) unsoluble lignin was transformed to aromatic-type chars directly after deeper crosslinking of aromatic chains and the removal of excess oxygen functionality, which was "heterogeneous" route. Both two routes were believed to exist in the real hydrothermal carbonization of lignin, [7] and possibly made the morphologies and properties of the obtained chars greatly different. It can be expected that replacing water with organic solvents in biomass carbonization would do some help for changing "heterogeneous" route to"homogeneous-like" one, although it is less studied. A case using organic alcohol to assist biomass carbonization was reported by Zheng et al, [8] who used the mixture of alcohol and water at 550 o C to produce uniform carbonaceous spheroids with different symmetric shape from glucose, sucrose and starch. For lignin carbonization, supercritical ethanol was introduced to prepare lignin chars in our previous work, [9] which were then sulfonated to prepare solid acids and used in the esterification of oleic acid and the transesterification of Jatropha oil to biodiesel. Sulfonated catalyst derived from alcohothermal carbonization of lignin possessed similar surface acidity (5.05 vs. 5.35 mmol [H + ] g À1 ) but much higher BET surface (113.1 vs. 2.7 m 2 g À1 ) than sulfonated pyrolytic char. It was believed that the solvothermal carbonization of lignin in organic solvents was remarkable different from that through hydrothermal or pyrolytic routes, which might influence the performance of sulfonated catalyst. Results and discussionHere, the sol...

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

The Formation of Char, Gaseous and Liquid Products during Lignin Carbonization in Super‐ and Subcritical Solvents

Luo

Yang

et al. 2017

ChemistrySelect

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“…The most advanced analytical methodologies allowed the identification and structural characterization of low molecular weight species, e.g., the lignin p -bis(2,6-dimethoxyphenol)yl dimers [ 39 ], but also characterization of the differences between native lignins [ 40 ] and technical lignins resulting from the above-mentioned processing [ 41 , 42 , 43 , 44 , 45 , 46 ] ( Figure 4 ).…”

Section: Main Sources Of Natural Phenol Polymersmentioning

confidence: 99%

Natural Phenol Polymers: Recent Advances in Food and Health Applications

Panzella

Napolitano

2017

Antioxidants

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Natural phenol polymers are widely represented in nature and include a variety of classes including tannins and lignins as the most prominent. Largely consumed foods are rich sources of phenol polymers, notably black foods traditionally used in East Asia, but other non-edible, easily accessible sources, e.g., seaweeds and wood, have been considered with increasing interest together with waste materials from agro-based industries, primarily grape pomace and other byproducts of fruit and coffee processing. Not in all cases were the main structural components of these materials identified because of their highly heterogeneous nature. The great beneficial effects of natural phenol-based polymers on human health and their potential in improving the quality of food were largely explored, and this review critically addresses the most interesting and innovative reports in the field of nutrition and biomedicine that have appeared in the last five years. Several in vivo human and animal trials supported the proposed use of these materials as food supplements and for amelioration of the health and production of livestock. Biocompatible and stable functional polymers prepared by peroxidase-catalyzed polymerization of natural phenols, as well as natural phenol polymers were exploited as conventional and green plastic additives in smart packaging and food-spoilage prevention applications. The potential of natural phenol polymers in regenerative biomedicine as additives of biomaterials to promote growth and differentiation of osteoblasts is also discussed.

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“…16 It is a complex reaction, performed in a closed system using wet, carbohydrate rich biomass as raw materials under conditions of temperature (180-260 C) and high autogenous pressure. 17 At present, hydrothermal carbonization is predicted a large potential in the preparation of carbon materials or carbon composites with different properties. Some researchers use hydrothermal carbonization to hydrolyze viscous organic substances in sludge at a certain temperature and pressure.…”

Section: Introductionmentioning

confidence: 99%