Understanding changes in lignin of Panicum virgatum and Eucalyptus globulus as a function of ionic liquid pretreatment

Varanasi, Patanjali; Singh, Priyanka; Arora, Rohit; Adams, Paul D.; Auer, Manfred; Simmons, Blake A.; Singh, Seema

doi:10.1016/j.biortech.2012.08.070

Cited by 65 publications

(52 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In an aqueous IL system, the hydrogen bond basicity (β value) can be correlated with the disruption of the inter-and intramolecular hydrogen bondings in cellulose, hemicellulose, and lignin (Shi et al, 2014). It is likely that the G-lignin monomeric products obtained in this study were phenolic moieties of G-lignin caused by losing phenolic proton under alkaline conditions at low reaction temperatures (Varanasi et al, 2012). These results lead to the hypothesis that the temperature-dependent dual basic and acidic characteristics of an IL could serve as a design basis to tune the aqueous IL system for better lignin solubility and product selectivity (Park and Kazlauskas, 2003;Shi et al, 2014).…”

Section: Lignin Breakdown Product Identificationmentioning

confidence: 82%

“…Formation of vanillin from Kraft lignin by different oxidants such as H2O2, O2, and nitrobenzene in NaOH medium has been reported (Xiang and Lee, 2000;Rodrigues Pinto et al, 2010;Pandey and Kim, 2011). It was reported that the IL, [C2C1im] [OAc] possesses dual basic and acidic characteristics as a function of temperature (Varanasi et al, 2012). The hydrogen bond basicity (β) decreased by 1.4% with an increase in temperature from 120 to 160°C (Varanasi et al, 2012).…”

Section: Lignin Breakdown Product Identificationmentioning

confidence: 99%

“…It was reported that the IL, [C2C1im] [OAc] possesses dual basic and acidic characteristics as a function of temperature (Varanasi et al, 2012). The hydrogen bond basicity (β) decreased by 1.4% with an increase in temperature from 120 to 160°C (Varanasi et al, 2012). In an aqueous IL system, the hydrogen bond basicity (β value) can be correlated with the disruption of the inter-and intramolecular hydrogen bondings in cellulose, hemicellulose, and lignin (Shi et al, 2014).…”

Section: Lignin Breakdown Product Identificationmentioning

confidence: 99%

See 2 more Smart Citations

Catalytic Oxidation and Depolymerization of Lignin in Aqueous Ionic Liquid

Das

Shi

2017

Front. Energy Res.

View full text Add to dashboard Cite

Lignin is an integral part of the plant cell wall, which provides rigidity to plants, also contributes to the recalcitrance of the lignocellulosic biomass to biochemical and biological deconstruction. Lignin is a promising renewable feedstock for aromatic chemicals; however, an efficient and economic lignin depolymerization method needs to be developed to enable the conversion. In this study, we investigated the depolymerization of alkaline lignin in aqueous 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc] under oxidizing conditions. Seven different transition metal catalysts were screened in presence of H2O2 as oxidizing agent in a batch reactor. CoCl2 and Nb2O5 proved to be the most effective catalysts in degrading lignin to aromatic compounds. A central composite design was used to optimize the catalyst loading, H2O2 concentration, and temperature for product formation. Results show that lignin was depolymerized, and the major degradation products found in the extracted oil were guaiacol, syringol, vanillin, acetovanillone, and homovanillic acid. Lignin streams were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography to determine effects of the experimental parameters on lignin depolymerization. The weight-average molecular weight (Mw) of liquid stream lignin after oxidation, for CoCl2 and Nb2O5 catalysts were 1,202 and 1,520 g mol, respectively, lower than that of Kraft lignin. Polydispersity index of the liquid stream lignin increased as compared with Kraft lignin, indicating wide span of the molecular weight distribution as a result of lignin depolymerization. Results from this study provide insights into the role of oxidant and transition metal catalysts and the oxidative degradation reaction sequence of lignin toward product formation in presence of aqueous ionic liquid.

show abstract

Section: Lignin Breakdown Product Identificationmentioning

confidence: 82%

Section: Lignin Breakdown Product Identificationmentioning

confidence: 99%

Section: Lignin Breakdown Product Identificationmentioning

confidence: 99%

See 1 more Smart Citation

Catalytic Oxidation and Depolymerization of Lignin in Aqueous Ionic Liquid

Das

Shi

2017

Front. Energy Res.

View full text Add to dashboard Cite

show abstract

“…Furthermore, ILs can be easily prepared using different cations and anions, resulting in hydrophobic or hydrophilic types [6e8]. Ionic liquids have been utilized in the dissolution of both softwood and hardwood [9], depolymerization of hemicelluloses for yellow pine [10], and also delignification of eucalyptus, switchgrass and bagasse [11,12].…”

Section: Introductionmentioning

confidence: 99%

Characterization of ionic liquid pretreatment and the bioconversion of pretreated mixed softwood biomass

Trinh

Lee

et al. 2015

Biomass and Bioenergy

View full text Add to dashboard Cite

“…Varanasi concluded that with higher pretreatment times using 1-ethyl-3-methylimidazolium acetate ([C 2 mim] [OAc]). (6-12 h), it is easier to remove G-lignin at 120 o C and to remove Slignin at 160 o C (Varanasi et al 2012). The formation of new carbon-carbon bonds during acid-pretreatment leads to the disappearance of the G6 correlation and the obvious shift of G2 correlation due to the steric hindrance of the methoxyl group in the S units (Wang et al 2012).…”

Section: Introductionmentioning

confidence: 99%