High Yield Production of Natural Phenolic Alcohols from Woody Biomass Using a Nickel-Based Catalyst
Efficient depolymerization of woody biomass to produce natural phenolic alcohols not only preserves the original structure of lignin, but also makes the depolymerization process atom-efficient. Here, high yield production of natural phenolic alcohols (38.7 wt %) from woody biomass has been achieved using a Ni/C catalyst in a methanol–water co-solvent. The Ni-based catalyst can efficiently etherify the Cα?OH group in lignin β-O-4 motifs under hydrogen atmosphere, which can break the hydrogen bond between the Cβ?O oxygen and the Cα?OH proton to facilitate the Cβ?O cleavage. It was reported that water can also accelerate the etherification of raw lignin with methanol through in situ formation of acid. Our results suggest that breaking the intramolecular hydrogen bonds can accelerate the Cβ?O cleavage, keeping the original structure of lignin unchanged. This work highlights the significance of structure modification in lignin depolymerization and displays a clear potential for the valorization of whole biomass.
Chen, Jiazhi,Lu, Fang,Si, Xiaoqin,Nie, Xin,Chen, Junsheng,Lu, Rui,Xu, Jie
Mechanistic investigation of the Zn/Pd/C catalyzed cleavage and hydrodeoxygenation of lignin
While current biorefinery processes use lignin only for its heat value, the conversion of lignin to high value chemicals is an area of increasing interest. Herein we present a detailed mechanistic study of the hydrodeoxygenation (HDO) of lignin by using a synergistic Pd/C and ZnII catalyst through use of both lignin model compounds and lignocellulosic biomass. Spectroscopic data coupled with the study of lignin model compounds suggest that ZnII activates and facilitates removal of the hydroxyl group at the Cγ position of the β-O-4 ether linkage. Activation is proposed to occur through formation of a six-membered ring complex of ZnII coordinated to the oxygen atoms at Cα and Cγ of the lignin model compound guaiacylglycerol-β-guaiacyl.
Klein, Ian,Marcum, Christopher,Kentt?maa, Hilkka,Abu-Omar, Mahdi M.
p. 2399 - 2405
(2016/05/19)
Are quinone methides responsible for yellowing of paper in light?
Irradiation of tetrahydrofuran solutions of quinone methide 1 at 350 nm resulted in the formation of yellow oligomeric products and guaiacol. The rate constants determined for the disappearance of the starting compound and those of guaiacol formation show
Dolenc, Jozica,Sket, Boris,Strlic, Matija
p. 5669 - 5671
(2007/10/03)
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