title: Valorization of Lignin to Simple Phenolic Compounds over Tungsten Carbide: Impact of Lignin Structure.
abstract: Lignins isolated from representative hardwood, softwood, and grass materials were effectively hydrocracked to aromatics catalyzed by tungsten carbide over activated carbon (W2C/AC). The effects of botanical species and fractionation methods on lignin structure and the activity of W2C/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 W2C/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. β-O-4 bonds were the major linkages in all lignin samples, whereas softwood lignins contained more resistant linkages of β-5 and less β-β 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 W2C/AC exhibited high activity not only in β-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.
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.|University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors.forename: Haiwei
authors.initials: H
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.|College of Chemistry, Xiangtan University, Xiangtan, Hunan, 411105, P. R. China.
authors.forename: Zaojuan
authors.initials: Z
authors.lastname: Qi
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Changzhi
authors.initials: C
authors.lastname: Li
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.|Shaanxi Key Laboratory of Catalysis, School of Chemistry and Environment Science, Shaanxi Sci-tech University, Hanzhong, 723001, P. R. China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.|University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Aiqin
authors.initials: A
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
mesh_terms: D002384:Catalysis; D002606:Charcoal / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008031:Lignin / Q000737:chemistry*; D008970:Molecular Weight; D010636:Phenols / Q000737:chemistry*; D058105:Polymerization; D012997:Solvents / Q000737:chemistry; D017973:Tungsten Compounds / Q000737:chemistry*; D003313:Zea mays / Q000737:chemistry
chemical_list: D010636:Phenols; D012997:Solvents; D017973:Tungsten Compounds; C002802:tungsten carbide; D002606:Charcoal; D008031:Lignin
keywords: aromatics; biomass; lignin; methanol; tungsten carbide