Lignin Depolymerization with Phenol via Redistribution Mechanism in Ionic Liquids

Nanayakkara, Sepa; Patti, Antonio F.; Saito, Kei

doi:10.1021/sc5003424

Cited by 59 publications

(32 citation statements)

References 27 publications

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“…Recently ionic liquids (ILs) are extensively used for the conversion of cellulose, hemicellulose, and lignin into various value‐added chemicals . ILs have been employed as the solvent, additives, catalyst, etc.…”

Section: Introductionmentioning

confidence: 99%

Effect of Solvent, Role of Formic Acid and Rh/C Catalyst for the Efficient Liquefaction of Lignin

et al. 2019

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We demonstrate highly efficient liquefaction of alkali lignin with a very high yield of THF‐soluble bio‐oil (91.5 wt %) using formic acid (FA) and Rh/C catalyst under relatively mild reaction conditions (250 °C, 6 h) in EtOH−H2O co‐solvent system. The monomeric products are identified in which alkyl guaiacols accounts for the main proportion. The role of FA was not only used as a liquid‐phase in‐situ hydrogen source but also acts as organic acid which can catalyze the hydrolysis reaction of −C−O−C ether bonds of lignin. Moreover, in the present study, the role of Rh/C and FA is demonstrated for the liquefaction of lignin. The replacement of pure H2 gas by the liquid‐phase FA (hydrogen source) can effectively prevent the char formation. The utilization of Rh/C catalyst helps for the conversion of alkenyl guaiacols to alkyl guaiacols suggesting the hydrogenation of phenolic monomers and further cleavage by hydrogenation results in the formation of bio‐oil with lower molecular weight (Mn=466 g mol−1) as well as lower O/C ratio (0.26).

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Section: Introductionmentioning

confidence: 99%

Effect of Solvent, Role of Formic Acid and Rh/C Catalyst for the Efficient Liquefaction of Lignin

et al. 2019

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“…After Ar-NN-is coupled with AL, the intensity ratio of the band at 1510−1516 cm −1 to that at 1595− 1601 cm −1 increases because the NN stretching vibration is overlapped with the CC stretching vibration of benzene rings at 1510−1516 cm −1 . As shown in Figure 3, the intensity ratio is ∼0.82 for AL but increases to 1.10 for AL-azo-NO 2 and 1.16 for AL-azo-OCH 3 .…”

Section: ■ Results and Discussionmentioning

confidence: 81%

“…The characteristic absorption peak of AL is near 280 nm. Compared with that of AL, the spectra of AL-azo-NO 2 and AL-azo-OCH 3 show new characteristic absorption bands in the range of 300−500 nm, indicating that azophenyl has been successfully synthesized in the two polymers. The exact absorption location of the two ALazo polymers depends on the type of azo chromophore, the degree of functionalization, and the solvent.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Preparation of Photoresponsive Azo Polymers Based on Lignin, a Renewable Biomass Resource

Deng

Liu

Qian

et al. 2015

ACS Sustainable Chem. Eng.

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Lignin-based azo polymers are prepared from alkali lignin, a byproduct in spent liquor from the pulping and papermaking industry, and their structures and photochromic effects are characterized by elemental analysis, Fourier transform infrared, 1 H nuclear magnetic resonance, and ultraviolet−visible spectroscopy. Results show that only the 2-(4-nitrophenyl azo) phenol lignin-modified polymer (ALazo-NO 2 ) shows a significant photochromic effect, and its photoresponsive behavior is evidently slower than that of the synthetic polymer with a similar azo chromophore. For the 2-(4-methoxyphenyl azo) phenol lignin-modified polymer, its photoisomerization behavior was expected to be similar to that of azobenzene-type molecules, but its photoresponse is not obvious. The abnormal photochromic effect of AL-azo polymers is related to strong steric hindrance of lignin backbones. With addition of water (poor solvent), AL-azo-NO 2 shrinks gradually, which prevents azobenzene groups from isomerizing and results in a lower isomerization efficiency at higher water contents. Preparation of lignin-based azo polymers offers a novel source of azo polymers and provides a green and sustainable pathway for value-added utilization of lignin biomass recovered from the pulping industry.

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“…Depolymerization of lignin into value-added aromatics is one of the most important routes in biomass deconstruction [6]. Lignin is an excellent precursor for the synthesis of aromatic chemicals [3].…”

Section: Introductionmentioning

confidence: 99%

Oxidative Depolymerization of Lignin Using Supported Niobium Catalysts

et al. 2017

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Abstract:Valorization of lignin into aromatics has driven researchers for decades. In this research, niobium was deposited on oyster shells (OSNC) and carbon rods (CRNC) and tested as a catalyst for depolymerization of lignin. Catalysts (2%, 5%, and 8% loading) were synthesized via wet impregnation. Batch experiments were performed at 95 • C, using 8 g of lignin, and 1 g of catalyst. Our research indicates that niobium supported catalysts are effective in partial oxidation of lignin. Maximum vanillin concentration for OSNC was found to be 86.25 mg L −1 (0.1 wt%) at 5% niobium whereas, as for CRNC, maximum vanillin concentration was found to be 139.40 mg L −1 (0.17 wt%) at 2% niobium loading. Addition of hydrogen peroxide into the batch reactor decreased the concentration of vanillin production.

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Lignin Depolymerization with Phenol via Redistribution Mechanism in Ionic Liquids

Cited by 59 publications

References 27 publications

Effect of Solvent, Role of Formic Acid and Rh/C Catalyst for the Efficient Liquefaction of Lignin

Effect of Solvent, Role of Formic Acid and Rh/C Catalyst for the Efficient Liquefaction of Lignin

Preparation of Photoresponsive Azo Polymers Based on Lignin, a Renewable Biomass Resource

Oxidative Depolymerization of Lignin Using Supported Niobium Catalysts

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