Catalytic depolymerization of lignin macromolecule to alkylated phenols over various metal catalysts in supercritical tert-butanol

Kim, Jae‐Young; Park, Jeesu; Hwang, Hyewon; Kim, Jeong Kwon; Song, In Kyu; Choi, Joon Weon

doi:10.1016/j.jaap.2014.11.011

Cited by 76 publications

(58 citation statements)

References 42 publications

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“…Catalysts based on noble metals (Pd, Ru, Pt) and on the less expensive metals (Ni, Mo, etс.) supported on Al 2 O 3 , SiO 2 and carbon carries are used in the different processes of lignin valorization [8,[15][16]. In particular, the catalyst Ni/C shows the comparable with catalysts Pt/C, Pd/C, Ru/C activity in organosolv lignin depolymerization in supercritical butanol with obtaining of alcylated phenols [17].…”

Section: Introductionmentioning

confidence: 99%

Green catalytic processing of native and organosolv lignins

et al. 2018

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Two ways of catalytic depolymerization of native and isolated wood lignins are described: the peroxide delignification of hardwood (aspen, birch) and softwood (abies) in the medium of acetic acidwater over TiO 2 catalyst and the thermal dissolution of organosolv lignins (ethanol-lignin and acetone-lignin) in supercritical alcohols (ethanol and butanol) over solid Ni-containing catalysts. The catalyst TiO 2 in rutile modification has the higher activity in wood peroxide delignification at 100°C as compared to TiO 2 in anatase modification. The results of kinetic studies and optimization of the processes of peroxide depolymerization of hardwood (aspen, birch) and softwood (abies) lignins in the medium of acetic acidwater over catalyst TiO 2 (rutile) at mild conditions (≤ 100°C, atmospheric pressure) are compared. The catalyst TiO 2 initiates the formation of OH • and OOH • radicals from H 2 O 2 which promote the oxidative fragmentation of wood lignin. In this case, the peroxide depolymerization of softwood lignin, constructed from phenylpropane units of guaiacyl-type proceeds more difficult than the hardwood lignins, mainly containing syringyl-type units. The solid and soluble products of peroxide catalytic delignification of wood under the optimized conditions were studied by FTIR, XRD, GC-MS and chemical methods. Regardless of the nature of wood the cellulosic products have a structure similar to microcrystalline cellulose. The soluble products mainly consist of monosaccharides and organic acids. Aromatic compounds are present only in a low amount which indicates the oxidative degradation of aromatic rings of lignin phenylpropane units under the used conditions of wood catalytic delignification. The processes of thermal dissolution of acetone-lignin and ethanol-lignin from aspenwood in supercritical ethanol and butanol over Ni-containing catalyst (NiCu/SiO 2 , NiCuMo/SiO 2) are compared. The composition, structure and thermal properties of organosolv lignins were studied with the use of FTIR, GPC, 1 H-13 C HSQC NMR, DTA and elemental analysis. The influence of a composition of Ni-containing catalyst on the thermal conversion in supercritical butanol and ethanol of ethanol-lignin and acetone-lignin was established. The highest conversion of lignins (to 93% wt.) in supercritical alcohols and the highest yield of liquid products (to 90 % wt.) were achieved at 300 °C in the presence of catalyst NiCuMo/SiO 2. Scheme of green biorefinery of wood based on the use of non-toxic and low-toxic reagents (H 2 O 2 , H 2 O, acetic acid, ethanol, butanol) and solid catalysts (TiO 2 , NiCuMo/SiO 2) is suggested.

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Section: Introductionmentioning

confidence: 99%

Green catalytic processing of native and organosolv lignins

et al. 2018

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“…However, the physiochemical heterogeneity of lignin complicates its use as a feedstock. Many researchers have reported that the physiochemical properties of lignin, and its suitability for catalytic conversion and specific polymer applications are largely dependent on the structures, which rely on the source of lignin and the isolation method. The structure of lignin has a direct impact on the processability of lignin, particularly for fiber production .…”

Section: Introductionmentioning

confidence: 99%

Effects of Extraction Methods on Structure and Valorization of Corn Stover Lignin by a Pd/C Catalyst

et al. 2017

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With the significant development of efficient pretreatments of lignocellulosic biomass towards using carbohydrate compositions for biofuel production, the valorization of associated lignin products into valuable chemicals has gained much attention. Four lignins obtained by pretreatment of corn stover with emerging ionic liquid‐based mixed organic electrolytes (ILOE) and alkaline twin‐screw extrusion (ATSE) pretreatment technologies were characterized by gel permeation chromatography (GPC), FTIR, HSQC, 31P NMR spectroscopy, and SEM. These lignins were valorized by using Pd/C under various conditions, followed by an elucidation of the relationship between the lignin structure and valorization efficiency and selectivity. The pretreatment/separation methods have a significant effect on lignin structure and subsequent valorization efficiency. HSQC spectra revealed that corn stover lignin consisted of β‐O‐4, β‐5, β‐1 linkages, and cinnamyl alcohol end groups. The extracted lignins (EL) showed less carbohydrates and β‐O‐4 units than those of enzymatic hydrolytic lignins (EHL). The yields of bio‐oils were 61.7 % and 57.9 % for ATSE‐EL and ILOE‐EL, and 34.2 % and 45.1 % for ATSE‐EHL and ILOE‐EHL under optimal and comparative conditions, respectively. Part of the syringyl (S) units were converted into guaiacyl or p‐hydroxyphenyl (H) units by release of methoxyl groups on the aromatic ring through hydrogenolysis, which led to a decreased proportion of S units and an increased proportion of H units in oil compared with in lignin.

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“…In these studies, the catalysts play a major role in the conversion and the selectivity of the final products. The most widely used catalysts are Pd/C [81,[92][93][94][95][96], Ni/C [93][94][95][96][97], Pt/C [93][94][95]98], Pt/Al 2 O 3 [99], Cu-based porous oxides [100,101], supported NiW and NiMo [102], Ru-based materials [93][94][95][96]103], bimetallic NiM (M = Ru, Rh, Pd) [66], Ni-Au [65,104], WP [105], Ru x Ni 1-x /SBA-15 [106], modified SBA-15 and Al-SBA-15 [107], MoO x /CNT [108], S 2 O 8 2− -KNO 3 /TiO 2 [109]. Another significant parameter in the reductive depolymerization using molecular H 2 is the reaction medium.…”

Section: Depolymerization With External Hydrogen Sourcementioning

confidence: 99%

Catalytic Transfer Hydrogenolysis Reactions for Lignin Valorization to Fuels and Chemicals

Margellou

Triantafyllidis

2019

Catalysts

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Lignocellulosic biomass is an abundant renewable source of chemicals and fuels. Lignin, one of biomass main structural components being widely available as by-product in the pulp and paper industry and in the process of second generation bioethanol, can provide phenolic and aromatic compounds that can be utilized for the manufacture of a wide variety of polymers, fuels, and other high added value products. The effective depolymerisation of lignin into its primary building blocks remains a challenge with regard to conversion degree and monomers selectivity and stability. This review article focuses on the state of the art in the liquid phase reductive depolymerisation of lignin under relatively mild conditions via catalytic hydrogenolysis/hydrogenation reactions, discussing the effect of lignin type/origin, hydrogen donor solvents, and related transfer hydrogenation or reforming pathways, catalysts, and reaction conditions.

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Catalytic depolymerization of lignin macromolecule to alkylated phenols over various metal catalysts in supercritical tert-butanol

Cited by 76 publications

References 42 publications

Green catalytic processing of native and organosolv lignins

Green catalytic processing of native and organosolv lignins

Effects of Extraction Methods on Structure and Valorization of Corn Stover Lignin by a Pd/C Catalyst

Catalytic Transfer Hydrogenolysis Reactions for Lignin Valorization to Fuels and Chemicals

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