scholarly journals Formation of p-Unsubstituted Phenols in Base-catalyzed Lignin Depolymerization

2021 ◽  
Vol 333 ◽  
pp. 05006
Author(s):  
Shinji Kudo ◽  
Eriko Honda ◽  
Shingo Nishioka ◽  
Jun-ichiro Hayashi
Keyword(s):  
Functional Groups ◽  
Chemical Industry ◽  
Main Product ◽  
Lignin Valorization ◽  
Theoretical Maximum ◽  
Lignin Depolymerization

Lignin valorization is one of the biggest challenges for developing biomass-based chemical industry. Recent innovative works has enabled depolymerization of lignin to the monomers with the yield close to theoretical maximum. The main product is a mixture of phenols derived from the cleavage of β-O-4 linkages between phenylpropanoid units. However, the obtained highly functionalized phenols are not common in current industry and, therefore, needs further processing for the utilization in intended applications. The present study shows that simple phenols without functional groups at para-position form selectively in base-catalyzed depolymerization of lignin. The yield is not sufficiently high, up to 6.9% on a carbon basis under the examined conditions, but the selectivity among released lignin monomers reaches 80%. The study also discusses the mechanism of p-unsubstituted phenols formation.

Catalytic lignin valorization over HSZ-supported CuNiAl-based catalysts with microwave heating

2021 ◽  
Author(s):  
Peng Liu ◽  
Changzhou Chen ◽  
Minghao Zhou ◽  
Haihong Xia ◽  
Jing Li ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Metal Oxides ◽  
Microwave Heating ◽  
Mixed Metal Oxides ◽  
Lignin Valorization ◽  
Mixed Metal ◽  
Microwave Assisted ◽  
The Difference ◽  
Lignin Depolymerization

Microwave assisted lignin depolymerization was investigated over HSZ-supported CuNiAl based catalysts. The synergistic effect between acidic HSZ support and mixed metal oxides were studied in detail, to explore the difference...

scholarly journals Supported-Metal Catalysts in Upgrading Lignin to Aromatics by Oxidative Depolymerization

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 467
Author(s):  
Cédric Cabral Almada ◽  
Aleksandr Kazachenko ◽  
Pascal Fongarland ◽  
Denilson Da Silva Perez ◽  
Boris N. Kuznetsov ◽  
...  
Keyword(s):  
Gold Catalyst ◽  
Added Value ◽  
Supported Metal Catalysts ◽  
Lignin Valorization ◽  
Mild Conditions ◽  
Platinum Particles ◽  
Lignin Oxidation ◽  
Target Molecules ◽  
Supported Gold ◽  
Lignin Depolymerization

Supported gold and platinum particles on titanium oxide catalysts were evaluated in the oxidative depolymerization of lignins toward high added value aromatics under mild conditions (T: 150 °C, Pair: 20 bar, CNaOH: 10 g/L, 1 h). Kraft and ethanol Organosolv lignins were engaged in the study. Gold catalyst showed a strong tendency to further oxidize aromatics produced from lignin depolymerization to volatile compounds leading to very low yield in target molecules. On the contrary, platinum-based catalysts were allowed to observe enhanced yields that were attributed to its ability to preserve lignin’s substructure during the reaction. A kinetic model was constructed based on the results observed, which allowed us to identify the occurrence of condensation reactions during lignin oxidation and degradation of the produced aromatic compounds as the main limitations to reach high product yields. Insights on lignin oxidation and the catalyst’s role lead through this study would help to reach higher control over lignin valorization.

scholarly journals Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 98 ◽  
Author(s):  
Ricardo Abejón ◽  
Heriberto Pérez-Acebo ◽  
Leonardo Clavijo
Keyword(s):  
Bibliometric Analysis ◽  
Interdisciplinary Collaboration ◽  
Polymeric Materials ◽  
Lignin Valorization ◽  
Isolation And Characterization ◽  
Dominant Process ◽  
Number Of Publications ◽  
Main Components ◽  
Lignin Depolymerization

A complete bibliometric analysis of the Scopus database was performed to identify the research trends related to lignin valorization from 2000 to 2016. The results from this analysis revealed an exponentially increasing number of publications and a high relevance of interdisciplinary collaboration. The simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose, and lignin) has been revealed as a key aspect and optimal pretreatment is required for the subsequent lignin valorization. Research covers the determination of the lignin structure, isolation, and characterization; depolymerization by thermal and thermochemical methods; chemical, biochemical and biological conversion of depolymerized lignin; and lignin applications. Most methods for lignin depolymerization are focused on the selective cleavage of the β-O-4 linkage. Although many depolymerization methods have been developed, depolymerization with sodium hydroxide is the dominant process at industrial scale. Oxidative conversion of lignin is the most used method for the chemical lignin upgrading. Lignin uses can be classified according to its structure into lignin-derived aromatic compounds, lignin-derived carbon materials and lignin-derived polymeric materials. There are many advances in all approaches, but lignin-derived polymeric materials appear as a promising option.

The Clinical, Roentgenological and Morphological Effects of an Acute Exposure of Phosgene on the Lungs of Dogs

1971 ◽  
Vol 29 ◽  
pp. 236-237
Author(s):  
R. F. Bils ◽  
W. F. Diller ◽  
F. Huth
Keyword(s):  
Latent Period ◽  
Chemical Industry ◽  
Toxic Substance ◽  
Lung Edema ◽  
X Rays ◽  
Beagle Dogs ◽  
Male And Female ◽  
Morphological Alterations ◽  
Before And After ◽  
Electron Microscopes

Phosgene still plays an important role as a toxic substance in the chemical industry. Thiess (1968) recently reported observations on numerous cases of phosgene poisoning. A serious difficulty in the clinical handling of phosgene poisoning cases is a relatively long latent period, up to 12 hours, with no obvious signs of severity. At about 12 hours heavy lung edema appears suddenly, however changes can be seen in routine X-rays taken after only a few hours' exposure (Diller et al., 1969). This study was undertaken to correlate these early changes seen by the roengenologist with morphological alterations in the lungs seen in the'light and electron microscopes.Forty-two adult male and female Beagle dogs were selected for these exposure experiments. Treated animals were exposed to 94.5-107-5 ppm phosgene for 10 min. in a 15 m3 chamber. Roentgenograms were made of the thorax of each animal before and after exposure, up to 24 hrs.

Improving integration between functional groups: A case in organization change and implications for theory and practice

1971 ◽  
Author(s):  
Warren G. Bennis ◽  
Michael Beer ◽  
Gerald R. Pieters ◽  
Alan T. Hundert ◽  
Samuel H. Marcus ◽  
...  
Keyword(s):  
Functional Groups ◽  
Organization Change ◽  
Theory And Practice

HYDROXYAPATITE, ALGINATE, AND CHITOSAN FOR BONE SCAFFOLDS: SPECTROSCOPY STUDY

2016 ◽  
Vol 19 (2) ◽  
pp. 93-100
Author(s):  
Lalita El Milla
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Functional Groups ◽  
Bone Growth ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Tissue Engineering Scaffolds ◽  
Hydroxyapatite Powder ◽  
Materials Used

Scaffolds is three dimensional structure that serves as a framework for bone growth. Natural materials are often used in synthesis of bone tissue engineering scaffolds with respect to compliance with the content of the human body. Among the materials used to make scafffold was hydroxyapatite, alginate and chitosan. Hydroxyapatite powder obtained by mixing phosphoric acid and calcium hydroxide, alginate powders extracted from brown algae and chitosan powder acetylated from crab. The purpose of this study was to examine the functional groups of hydroxyapatite, alginate and chitosan. The method used in this study was laboratory experimental using Fourier Transform Infrared (FTIR) spectroscopy for hydroxyapatite, alginate and chitosan powders. The results indicated the presence of functional groups PO43-, O-H and CO32- in hydroxyapatite. In alginate there were O-H, C=O, COOH and C-O-C functional groups, whereas in chitosan there were O-H, N-H, C=O, C-N, and C-O-C. It was concluded that the third material containing functional groups as found in humans that correspond to the scaffolds material in bone tissue engineering.

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