Back to Search
Start Over
Base-catalyzed oxidative depolymerization of softwood kraft lignin
- Source :
- Industrial Crops and Products. 152:112473
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- Lignin is an important aromatic biopolymer with the structure based on phenolic units. Depolymerized lignin materials can be useful substitutes for phenol in phenol-formaldehyde resins. Our aim was to examine the potential of the base-catalyzed oxidation method to provide reactive oligomeric lignin fragments from softwood kraft lignin through the cleavage of the ether bonds. Three different bases, namely, NaOH, KOH, and NH4OH, were used as the catalyst in an aerobic oxidation, in which the influence of the reaction time was examined for 2 h and 6 h. Oxidized lignin materials were characterized with high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and nuclear magnetic resonance spectroscopy (13C, 1H-13C HSQC, and 31P NMR). The presence of methanol in the oxidation gas phase and formation of carboxylic acids indicate that some of the lignin structures were degraded in the oxidation. Guaiacyl units, the major phenolic structure of softwood kraft lignin, survived the oxidation. The oxidatively depolymerized lignin materials showed a reactivity close to that of pristine lignin in a reaction with formaldehyde, as determined by differential scanning calorimetry (DSC). Overall, the FT-ICR MS, NMR, and DSC results proved that the oxidized lignin materials maintained their oligomeric nature and possess the reactivity with formaldehyde.
- Subjects :
- 0106 biological sciences
Softwood
010405 organic chemistry
Depolymerization
fungi
technology, industry, and agriculture
food and beverages
Ether
macromolecular substances
Nuclear magnetic resonance spectroscopy
complex mixtures
01 natural sciences
0104 chemical sciences
chemistry.chemical_compound
Differential scanning calorimetry
chemistry
Phenol
Organic chemistry
Lignin
Reactivity (chemistry)
Agronomy and Crop Science
010606 plant biology & botany
Subjects
Details
- ISSN :
- 09266690
- Volume :
- 152
- Database :
- OpenAIRE
- Journal :
- Industrial Crops and Products
- Accession number :
- edsair.doi...........e5803bd793b6ff3b2d36de66bb9d3446