Functionality and molecular weight distribution of red oak lignin before and after pyrolysis and hydrogenation

McClelland, Daniel J.; Motagamwala, Ali Hussain; Li, Yanding; Rover, Marjorie; Wittrig, Ashley M.; Wu, Chunping; Buchanan, J. Scott; Brown, Robert C.; Ralph, John; Dumesic, James A.; Huber, George W.

doi:10.1039/c6gc03515a

Cited by 83 publications

(88 citation statements)

References 50 publications

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“…It has been extensively studied on lignin and liquefaction products. [45][46][47][48] But a careful calibration must be achieved due to potential chemical interactions between lignin molecules and the column. [49] The different structure (hydrodynamic volume) between lignin products and calibration standards also impairs the quality of the molar masses determined by GPC.…”

Section: Introductionmentioning

confidence: 99%

Lignin Depolymerization: A Comparison of Methods to Analyze Monomers and Oligomers

et al. 2020

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Catalytic liquefaction of lignin is an attractive process to produce fuels and chemicals, but it forms a wide range of liquid products from monomers to oligomers. Oligomers represent an important fraction of the products and their analysis is complex. Therefore, rapid characterization methods are needed to screen liquefaction conditions based on the distribution in monomers and oligomers. For this purpose, UV spectroscopy is proposed as a fast and simple method to assess the composition of lignin‐derived liquids. UV absorption and fluorescence were studied on various model compounds and liquefaction products. Liquefaction of Soda lignin was conducted in an autoclave, in ethanol and with Pt/C catalyst (H2, 250 °C, 110 bar). Liquids were sampled at isothermal conditions every 30 min for 4 h. UV fluorescence spectroscopy is related to GC–MS, gel‐permeation chromatography (GPC), MALDI‐TOF MS, and NMR characterizations. A depolymerization index is proposed from UV spectroscopy to rapidly assess the relative distribution of monomers and oligomers.

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Section: Introductionmentioning

confidence: 99%

Lignin Depolymerization: A Comparison of Methods to Analyze Monomers and Oligomers

et al. 2020

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“…Other studies like (McClelland et al, ) combining NMR, Fourier‐transform ion cyclotron resonance mass spectrometer (FT‐ICR), and SEC analyses delivered also new information of lignin degradation pathways via oligomeric compounds. The SEC method was performed with THF as mobile phase and calibration with polystyrene, so solubility and calibration issues must be considered.…”

Section: Resultsmentioning

confidence: 99%

Lignin from bark as a resource for aromatics production by hydrothermal liquefaction

et al. 2018

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Biorefineries, which are using mostly unused side streams of other existing processes like bark or lignin, have a huge potential to open new resources, for example, chemicals. But with new resources new challenges will be met along the way. These challenges must be addressed and discussed to build a solid and far‐sighted process. This work focuses on the formation of monocyclic compounds like catechol as a valuable product during the hydrothermal liquefaction of beech wood bark as well as Kraft lignin from pine wood like Indulin AT. The focus is to get a better knowledge of the behavior of bark during hydrothermal liquefaction for depolymerization aiming at the production of aromatic building blocks for chemicals. Therefore, the influence, for example, of temperature and reaction time, the chemical reaction pathways, and the therefore necessary analytics need to be understood. Several limitations and challenges of common analytical methods are discussed and compared for bark and Kraft lignin, which is relatively well investigated and can act as a reference material to build a common ground and make it possible to build standards for all bioeconomic processes. Hydrothermal conditions increase the yield and selectivity toward bifunctional molecules like catechol. With rising temperatures and longer retention times, the catechol mass yields get lower. At temperatures above 350°C, nearly no catechol could be found any more. Different types of wood deliver different lignin compositions in terms of the monomeric units. However, it can be observed that different lignins show the same trends in regard to the catechol yield concerning temperatures and reaction time dependence, but overall a different product spectrum.

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“…Polyaromatics are regarded as the main precursors for the formation of deposited carbon species during the aromatization of pure alcohol . However, compared with the aromatization procedure of pure alcohol, not only polyaromatics would be generated in GTA process, but also a large amount of aldehydes and ketones could be produced, which could also be transformed into oxygen‐containing coke species via aldol condensation . As can also be seen in Figure and Table , except for the catalyst lifetime (defined as the time at which the BTX aromatics yields were less than 3 wt %), glycerol/alcohol mixture exhibited similar combustion peaks as glycerol/water mixture, indicating that only the coking rate was reduced after the introduction of alcohol into glycerol, while both the amount and type of coke were little affected.…”

Section: Resultsmentioning

confidence: 99%

Study on Catalytic Performance and Deactivation Behavior of HZSM‐5 in Aromatization of Glycerol

et al. 2018

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We have investigated both the catalytic performance and deactivation behavior of HZSM‐5 under aromatization of glycerol condition which represents an alternative aromatics manufacturing route for using “green” fuel sources to replace the traditional fossil fuels. The effects of solvents, glycerol contents, reaction temperature and weight hourly space velocity (WHSV) on product distribution and coking process over HZSM‐5 were studied. Three stages could be clearly distinguished in HZSM‐5 catalyzed glycerol to aromatics (GTA) process: induction stage, auto‐catalytic stage and rapid deactivation stage. The synergetic effect between methanol and glycerol promoted the conversion of glycerol dehydrated products into aromatic hydrocarbons, resulting in higher yields of aromatics and lower coking rate. More glycerol content in the feed would result in more low temperature coke originated from aldehydes/ketones and less high temperature coke derived from polyaromatics. Under the selected optimum reaction conditions of 450 °C, WHSV=0.71 mL ⋅ g−1 ⋅ h−1 with an methanol/glycerol ratio of 40/60 over HZSM‐5 catalyst, the aromatics yields reached 42.1 % and the catalyst lifetime was 14.5 h. Higher temperature and lower WHSV benefited the production of harder coke while lower temperature and higher WHSV enhances the formation of softer coke.

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Functionality and molecular weight distribution of red oak lignin before and after pyrolysis and hydrogenation

Abstract: GVL lignin, pyrolytic lignin, and hydrogenated pyrolytic lignin were studied and characterized by FT-ICR MS, GPC, and NMR.

Cited by 83 publications

References 50 publications

Lignin Depolymerization: A Comparison of Methods to Analyze Monomers and Oligomers

Lignin Depolymerization: A Comparison of Methods to Analyze Monomers and Oligomers

Lignin from bark as a resource for aromatics production by hydrothermal liquefaction

Study on Catalytic Performance and Deactivation Behavior of HZSM‐5 in Aromatization of Glycerol

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