Selective catalytic tailoring of the H unit in herbaceous lignin for methyl <i>p</i>-hydroxycinnamate production over metal-based ionic liquids

Li, Zhangmin; Cai, Zhenping; Zeng, Qiang; Zhang, Tian; Song, Chenyu; Zhang, Yaqin; He, Hongyan; Jiang, Lilong; Long, Jinxing; Li, Xuehui

doi:10.1039/c8gc01252k

Cited by 63 publications

(57 citation statements)

References 52 publications

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“…Although the production of arenes, cycloalkanes, and phenol from lignin is the main direction for upgrading lignin‐derived monomers, the synthesis of other value‐added chemicals, such as ethylbenzene, indane, terephthalic acid, diethyl maleate, acetic acid, and methyl‐substituted amines, has received gradually increasing attention in the last two years and becomes a new research hotspot . When targeting ethylbenzene and indane, attention should be paid to modification of the aforementioned Ru‐based catalysts .…”

Section: Upgrading Of Lignin‐derived Monomersmentioning

confidence: 99%

Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen

et al. 2020

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Lignin is the most abundant biopolymer with aromatic building blocks and its valorization to sustainable chemicals and fuels has extremely great potential to reduce the excessive dependence on fossil resources, although such conversions remain challenging. The purpose of this Review is to present an insight into the catalytic conversion of lignin involving hydrogen, including reductive depolymerization and the hydrodeoxygenation of lignin‐derived monomers to arenes, cycloalkanes and phenols, with a main focus on the catalyst systems and reaction mechanisms. The roles of hydrogenation sites (Ru, Pt, Pd, Rh) and acid sites (Nb, Ti, Mo), as well as their interaction in selective hydrodeoxygenation reactions are emphasized. Furthermore, some inspirational strategies for the production of other value‐added chemicals are mentioned. Finally, some personal perspectives are provided to highlight the opportunities within this attractive field.

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Section: Upgrading Of Lignin‐derived Monomersmentioning

confidence: 99%

Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen

et al. 2020

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“…However, the products are composed of a wide range of chemical compounds. To avoid this disadvantage and make the product more suitable for direct use as either industrial feedstock or fuel, more recently Li et al (2018) proposed a remarkable method, that is different from previous C-O or C-C cleavage approaches. In particular, the selective catalytic tailoring the H unit ( p CA) in herbaceous lignin for MPC production can be realized over metal-based ionic liquids (MBILs), as MPC has a similar structure to that of p-coumaric acid ester, a typical H structural unit in herbaceous lignin.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Insights Into the Depolymerization Mechanism of Lignin to Methyl p-hydroxycinnamate by [Bmim][FeCl4] Ionic Liquid

Zhang

Wang

et al. 2019

Front. Chem.

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Depolymerization of lignin into valuable aromatic compounds is an important starting point for its valorization strategies, which requires the cleavage of C-O and C-C bonds between lignin monomer units. The catalytic cleavage of these bonds is still difficult and challenging. Our previous experimental investigation (Green Chem., 2018, 20: 3743) has shown that methyl p-hydroxycinnamate ( MPC ) can be produced from molecular tailoring of H unit in lignin by the cleavage of the γ-O ester bond. In this study, the mechanism of [Bmim][FeCl 4 ]-catalyzed depolymerization of lignin was investigated by using the density functional theory (DFT) method. The results reveal that [FeCl 4 ] − anion of the catalyst plays a decisive role in the whole catalytic process, where two possible activation modes including three different potential reaction pathways can realize the depolymerization of lignin model compound. The calculated overall barriers of the catalytic conversion along these potential routes show that the third potential pathway, i.e., methanol firstly activated by [Bmim][FeCl 4 ], has the most probability with the lowest energy barrier, while the second pathway is excluded because the energy barrier is too high. Also, the results illustrate that the solvent effect is beneficial to the reduction of the relative energy for the reaction to form the transition states. Hence, the obtained molecular level information can identify the favorable conversion process catalyzed by metallic ionic liquids to a certain extent, and it is desirable to enhance the utilization of biomass as a ubiquitous feedstock.

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“…In order to evaluate the solvation effect on the reaction profiles, the Gibbs free energies were refined at the M06-2x/6-311+g(d,p) level of theory. According to experimental results, methanol was chosen as the SMD solvent because of its fine performance for lignin depolymerization (Singh and Dhepe, 2016; Li et al, 2018). The energy profiles of the three reaction routes are shown in Figure 5; the energies under vacuum are denoted in solid lines and those under solvent condition are denoted in dash lines.…”

Section: Resultsmentioning

confidence: 99%

“…Recent studies have presented that the selective tailor for ester bonds, rather than the ether bonds of lignin, yields methyl p-hydroxycinnamate with [Bmim][FeCl 4 ]. The high catalytic activity was attributed to the narrow HOMO-LUMO gap between ester lignin and [FeCl 4 ] − anion (Li et al, 2018). The efficient degradation of lignin using acidic IL, 1-(4- sulfobutyl)-3-methylimidazoliumhydrosulfate ([C 4 H 8 SO 3 Hmim][HSO 4 ]), was investigated (Long et al, 2015), yielding useful fine aromatic chemicals such as guaiacol, phenol and 4-ethylphenol through dehydration and dealkylation of lignin.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Elucidation of β-O-4 Bond Cleavage of Lignin Model Compound Promoted by Sulfonic Acid-Functionalized Ionic Liquid

et al. 2019

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While the depolymerization of lignin to chemicals catalyzed by ionic liquids has attracted significant attention, the relevant molecular mechanism, especially the cleavage of specific bonds related to efficient depolymerization, still needs to be deeply understood for the complexity of this natural aromatic polymer. This work presents a detailed understanding of the cleavage of the most abundant β-O-4 bond in the model system, guaiacylglycerol β-guaiacyl ether, by a Brønsted acidic IL (1-methyl-3-(propyl-3-sulfonate) imidazolium bisulfate ([C 3 SO 3 Hmim][HSO 4 ]) using density functional theory calculation and molecular dynamics simulation. It has been found that [C 3 SO 3 Hmim][HSO 4 ] generates zwitterion/H 2 SO 4 via proton transfer with an energy barrier of 0.38 kcal/mol, which plays a dominant role in the lignin depolymerization process. Subsequently, the reaction can be carried out via three potential pathways, including (1) the dehydration of α-C-OH, (2) dehydration of γ-C-OH, and (3) the protonation of β-O. The electrophilic attack of H 2 SO 4 and the hydrogen-bonding interaction between GG and zwitterion are the two most important factors to promote the depolymerization reaction. In all steps, the dehydration of α-C-OH route is computed to be favored for the experiment. The relatively higher energy barrier for β-O-4 bond dissociation among these reaction steps is attributed to the hindrance of the self-assembled clusters of GG in the mixed system. Further, the dense distribution of H13([C 3 SO 3 Hmim]) surrounding O21(GG), indicated by sharp peaks in RDFs, reveals that -SO 3 H in cations plays a substantial role in solvating lignin. Hopefully, this work will demonstrate new insights into lignin depolymerization by functionalized ILs in biomass conversion chemistry.

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Selective catalytic tailoring of the H unit in herbaceous lignin for methyl p-hydroxycinnamate production over metal-based ionic liquids

Abstract: Selective catalytic tailoring of herbaceous lignin for the production of methyl p-hydroxycinnamate (MPC).

Cited by 63 publications

References 52 publications

Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen

Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen

Theoretical Insights Into the Depolymerization Mechanism of Lignin to Methyl p-hydroxycinnamate by [Bmim][FeCl4] Ionic Liquid

Theoretical Elucidation of β-O-4 Bond Cleavage of Lignin Model Compound Promoted by Sulfonic Acid-Functionalized Ionic Liquid

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