title: Selective Cleavage of the Aryl Ether Bonds in Lignin for Depolymerization by Acidic Lithium Bromide Molten Salt Hydrate under Mild Conditions.
abstract: The present study demonstrates that the concentrated lithium bromide (LiBr) solution with acid as catalyst was able to selectively cleave the β-O-4 aryl ether bond and lead to lignin depolymerization under mild conditions (e.g., in 60% LiBr with 0.3 M HCl at 110 °C for 2 h). Four industrial lignins from different pulping and biorefining processes, including softwood kraft lignin (SKL), hardwood kraft lignin (HKL), softwood ethanol organosolv lignin (EOL), and acid corncob lignin (ACL), were treated in the LiBr solution. The molecular weight, functional group, and interunit linkages of the lignins were characterized using GPC, FTIR, and NMR. The results indicated that the β-O-4 aryl ether bonds of the lignins were selectively cleaved, and both LiBr and HCl played crucial roles in catalyzing the cleavage of the ether bonds.
authors.affiliation: Institute of Chemical Industry of Forestry Products, Chinese Academy of Forestry , Nanjing 210042, China.|Department of Biological Systems Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Xuliang
authors.initials: X
authors.lastname: Lin
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Pan
authors.affiliation: Institute of Chemical Industry of Forestry Products, Chinese Academy of Forestry , Nanjing 210042, China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D001965:Bromides / Q000737:chemistry*; D002850:Chromatography, Gel; D007221:Industry; D008031:Lignin / Q000737:chemistry*; D018020:Lithium Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008970:Molecular Weight; D058105:Polymerization; D017550:Spectroscopy, Fourier Transform Infrared; D014934:Wood / Q000737:chemistry; D003313:Zea mays / Q000737:chemistry
chemical_list: D001965:Bromides; D018020:Lithium Compounds; C040949:lithium bromide; D008031:Lignin
keywords: aryl ether bond; depolymerization; inorganic molten salt hydrate; lignin; lithium bromide