A method for judging the molecular structure of oligomers in lignin liquid phase depolymerization products
A technology of depolymerization products and molecular structure, applied in the direction of analysis of materials, preparation of test samples, analysis by nuclear magnetic resonance, etc., can solve problems such as less research
Active Publication Date: 2019-07-12
SOUTHEAST UNIV
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At present, there are many reports on the structural yield of monophenolic compounds in depolymerization products, but there are few studies on the determination and distribution of oligomer molecular structures with relatively large molecular weight (200-500) in oil phase products. Further in-depth research in order to understand the law of lignin liquid phase depolymerization and provide technical guidance for improving the yield of target products
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[0019] The present invention provides a method for determining the molecular structure of oligomers in lignin liquid phase depolymerization products. The method is carried out by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) on lignin liquid phase depolymerization products. For analysis, first determine the molecular weight corresponding to the product with a larger peak in the spectrum detected by TOF-MS. reuse 13 C-NMR qualitatively and quantitatively characterizes the type and distribution of the main linkages in oligomers. The structural main body of lignin is the carbon frame C of the phenylpropane structural unit 6 -C 3 , the main functional groups are hydroxyl (-OH) and methoxyl (-OCH 3 ), combined with the molecular weight of the oligomer and different types of linkages, and obeying the principle of saturation, the possible molecular structure of the oligomer was deduced. In the TOF-MS characterization results, the rati...
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The invention discloses a method for deducing molecular structures of oligomers in liquid phase depolymerization products of lignin. Lignin and alcohols solvents are mixed and added into a microwave reaction pot, microwave liquid phase degradation is carried out, matrix-assisted laser desorption / ionization time-of-flight mass spectrometry representation experiments are carried out for separated depolymerization products, molecular weights of oligomers whose peak values are higher in the products are obtained, ratios of absolute peak areas of oligomers are calculated, and relative content of each oligomer is obtained; a 13C-NMR experiment is carried out for depolymerization products, types of main connecting bonds and distribution thereof of oligomers in the depolymerization products are qualitatively and quantitatively represented; the structural main body of lignin is a carbon skeleton C6-C3 of a phenylpropanoid structure unit, main functional groups comprise hydroxyl radical (-OH) and methoxyl group (-OCH3), molecular weights of oligomers and different types of connecting bonds are combined, a saturability principle is obeyed, and possible molecular structures of oligomers in the depolymerization products are reckoned; a matrix model is established by using the data, and a distribution case of oligomers in the products is reckoned.
Description
technical field [0001] The invention belongs to the technical field of lignin utilization, and mainly relates to a method for judging the molecular structure of oligomers in lignin liquid-phase depolymerization products. Background technique [0002] Lignin is an abundant renewable organic resource in nature, which widely exists in plant fiber raw materials. Its production in nature is second only to cellulose, and it is the most abundant natural aromatic polymer substance. The molecular structure and aggregate structure of lignin are very complex, and human beings have not yet fully understood it. Therefore, being able to effectively use these resources is a long-cherished wish of human beings, and it is also the fundamental purpose of people's research on lignin chemistry. [0003] Liquefaction degradation of lignin has become an important method of lignin degradation because of its relatively mild reaction conditions and relatively short reaction time. Patent CN103724189...
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IPC IPC(8): G01N27/64G01N24/08G01N1/44
CPCG01N1/44G01N24/08G01N27/64
Inventor 沈德魁刘娜娜肖睿
Owner SOUTHEAST UNIV