Valorization of Lignin to Simple Phenolic Compounds over Tungsten Carbide: Impact of Lignin Structure.

Title Valorization of Lignin to Simple Phenolic Compounds over Tungsten Carbide: Impact of Lignin Structure.
Authors H. Guo; B. Zhang; Z. Qi; C. Li; J. Ji; T. Dai; A. Wang; T. Zhang
Journal ChemSusChem
DOI 10.1002/cssc.201601326
Abstract

Lignins isolated from representative hardwood, softwood, and grass materials were effectively hydrocracked to aromatics catalyzed by tungsten carbide over activated carbon (W2 C/AC). The effects of botanical species and fractionation methods on lignin structure and the activity of W2 C/AC were studied in detail. Gas permeation chromatography (GPC), FTIR, elemental analysis, and 2?D HSQC?NMR showed that all the extracted samples shared the basic skeleton of lignin, whereas the fractionation method significantly affected the structure. The organosolv process provided lignin with a structure more similar to the native lignin, which was labile to be depolymerized by W2 C/AC. Softwood lignins (i.e., spruce and pine) possessed higher molecular weights than hardwood lignins (i.e., poplar and basswood); whereas corn stalk lignin that has noncanonical subunits and exhibited the lowest molecular weight owing to its shorter growth period. ?-O-4 bonds were the major linkages in all lignin samples, whereas softwood lignins contained more resistant linkages of ?-5 and less ?-? than corn stalk and hardwood lignins; as a result, lowest hydrocracking efficiency was obtained in softwood lignins, followed by corn stalk and hardwood lignins. 2?D HSQC?NMR spectra of lignin and the liquid oil as well as the solid residue showed that W2 C/AC exhibited high activity not only in ?-O-4 cleavage, but also in deconstruction of other ether linkages between aromatic units, so that high yield of liquid oil was obtained from lignin.

Citation H. Guo; B. Zhang; Z. Qi; C. Li; J. Ji; T. Dai; A. Wang; T. Zhang.Valorization of Lignin to Simple Phenolic Compounds over Tungsten Carbide: Impact of Lignin Structure.. ChemSusChem. 2017;10(3):523532. doi:10.1002/cssc.201601326

Related Elements

Tungsten

See more Tungsten products. Tungsten (atomic symbol: W, atomic number: 74) is a Block D, Group 6, Period 6 element with an atomic weight of 183.84. The number of electrons in each of tungsten's shells is [2, 8, 18, 32, 12, 2] and its electron configuration is [Xe] 4f14 5d4 6s2. Tungsten Bohr ModelThe tungsten atom has a radius of 139 pm and a Van der Waals radius of 210 pm. Tungsten was discovered by Torbern Bergman in 1781 and first isolated by Juan José Elhuyar and Fausto Elhuyar in 1783. In its elemental form, tungsten has a grayish white, lustrous appearance. Elemental TungstenTungsten has the highest melting point of all the metallic elements and a density comparable to that or uranium or gold and about 1.7 times that of lead. Tungsten alloys are often used to make filaments and targets of x-ray tubes. It is found in the minerals scheelite (CaWO4) and wolframite [(Fe,Mn)WO4]. In reference to its density, Tungsten gets its name from the Swedish words tung and sten, meaning heavy stone.

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