Catalytic depolymerization of lignin via transfer hydrogenation strategy over skeletal CuZnAl catalyst

Huang, Yao‐Bing; Zhang, Jilong; Zhang, Xuan; Xue, Liyan; Chen, Hao-ze; Hu, Bin; Zhao, Li; Wu, Yuankui; Lü, Qiang

doi:10.1016/j.fuproc.2022.107448

Cited by 19 publications

(3 citation statements)

References 41 publications

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“…Moreover, ether bond cleavage and hydroxyl group elimination reactions may take place, leading to the formation of methoxyphenolic monomers. Additionally, different catalysts may lead to secondary reactions such as hydrogenation and deoxygenation, resulting in the formation of monophenolic compounds, cyclic alcohols, or cyclic hydrocarbon compounds [67]. It is worth noting that lignin monomer yields obtained through different catalytic methods cannot be easily compared since lignin structure and composition vary depending on the extraction method used and the source plant.…”

Section: Reductive Degradationmentioning

confidence: 99%

Structural Characteristics–Reactivity Relationships for Catalytic Depolymerization of Lignin into Aromatic Compounds: A Review

Wang

Zhang

et al. 2023

IJMS

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Developing renewable biomass resources is an urgent task to reduce climate change. Lignin, the only renewable aromatic feedstock present in nature, has attracted considerable global interest in its transformation and utilization. However, the complexity of lignin’s structure, uncertain linkages, stability of side chain connection, and inevitable recondensation of reaction fragments make lignin depolymerization into biofuels or platform chemicals a daunting challenge. Therefore, understanding the structural characteristics and reactivity relationships is crucial for achieving high-value utilization of lignin. In this review, we summarize the key achievements in the field of lignin conversion with a focus on the effects of the β-O-4 content, S/G ratio, lignin sources, and an “ideal” lignin—catechyl lignin. We discuss how these characteristics influence the formation of lignin monomer products and provide an outlook on the future direction of lignin depolymerization.

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Section: Reductive Degradationmentioning

confidence: 99%

Structural Characteristics–Reactivity Relationships for Catalytic Depolymerization of Lignin into Aromatic Compounds: A Review

Wang

Zhang

et al. 2023

IJMS

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“…Alcohol solvents are perhaps the most intriguing hydrogen donors; they are readily synthesized from the polysaccharide fractions of biomass and can function simultaneously as the reducing agent and reaction solvent. Several existing examples of catalytic transfer hydrogenation/hydrogenolysis (CTH) of lignin employ ethanol or 2-propanol with a variety of catalysts, including those based on Ni, − Cu, − Ru, − Cs, bimetallic species, − and noble metals. − These and other catalysts and systems for lignin transfer hydrogenation and hydrogenolysis have been thoroughly reviewed elsewhere. ,− …”

Section: Introductionmentioning

confidence: 99%

Catalytic Transfer Hydrogenolysis of Switchgrass Lignin with Ethanol Using Spinel-Type Mixed-Metal Oxide Catalysts Affords Control of the Oxidation State of Isolated Aromatic Products

Godwin,

Babusci,

Wonderling

et al. 2024

ACS Sustainable Chem. Eng.

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Chemical reductions of lignin are useful to remove oxygen and create product slates that can function as renewable platform molecules for new fuels and chemicals. Catalytic transfer hydrogenolysis (CTH) is an underexplored method to reduce lignin that obviates the use of dangerous and nonrenewable hydrogen gas. While noble metals are used extensively as catalysts for transfer hydrogenation, sustainability remains a major challenge to their deployment. In this work, we synthesized mixed-metal oxides of earth-abundant Co and Ni and characterized the catalysts using powder X-ray diffraction (XRD). Catalyst reactivity for the CTH of acetophenone was also assessed. Among the catalysts tested, spinel NiCo 2 O 4 demonstrated the highest conversion of acetophenone (75%) and the highest selectivity for ethylbenzene (90%); thus, we applied it to valorize switchgrass lignin, extracted under mild operating conditions by cosolvent enhanced lignocellulosic fractionation (CELF). The catalytically depolymerized lignin showed an increase in the number of selectively deoxygenated monomeric compounds. As demonstrated using 2D-NMR spectroscopy, the lignin displayed highly reduced aliphatic carbons, resulting from the catalyst-mediated reduction reaction at the Cα sites. These results are critical to the further development of the lignin-first biorefinery as they demonstrate the use of sustainable catalyst materials and mild transformation conditions to generate and refine a suite of new bioproducts.

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“…License: CC BY-NC-ND 4.0 the reducing agent and reaction solvent. Several examples of catalytic transfer hydrogenation/hydrogenolysis (CTH) of lignin exist which employ ethanol or 2-propanol with a variety of catalysts, including those based on Ni, [24][25][26][27][28] Cu, [29][30][31] Ru, [32][33][34][35][36][37] Cs, 38 bimetallic species, [39][40][41][42][43] and noble metals. [44][45][46][47] These and other catalysts and systems for lignin transfer hydrogenation and hydrogenolysis have been thoroughly reviewed elsewhere.…”

Section: Introductionmentioning

confidence: 99%

Catalytic transfer hydrogenolysis of switchgrass lignin with ethanol using spinel-type mixed-metal oxide catalysts affords control of the oxidation state of isolated aromatic products

Godwin,

Babusci,

Wonderling

et al. 2023

Preprint

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Chemical reductions of lignin are useful to remove oxygen and create product slates that can function as renewable platform molecules for new fuels and chemicals. Catalytic transfer hydrogenolysis (CTH) is an underexplored method to conduct reductions of lignin that obviates the use of dangerous and non-renewable hydrogen gas. While noble metals are used extensively as catalysts for transfer hydrogenation, one major challenge for their deployment is related to their sustainability. In this work, we synthesized mixed-metal oxides of earth-abundant Co and Ni. We characterized these catalysts using powder x-ray diffraction (XRD) and tested their reactivity for CTH of acetophenone. Among the catalysts we tested, we noted that the spinel NiCo2O4 demonstrated the highest conversion of acetophenone (75%) and highest selectivity for ethylbenzene (90%), so we applied it to valorization of switchgrass lignin extracted under mild operating conditions by cosolvent enhanced lignocellulosic fractionation (CELF). The catalytically depolymerized lignin showed an increase in selectively deoxygenated monomeric compounds. Using 2D-NMR spectroscopy, we demonstrated the lignin displayed highly reduced aliphatic carbons resulting from the reduction reaction at the Cα sites mediated by our catalyst material. These results are critical to the further development of the lignin-first biorefinery as they demonstrate the use of sustainable catalyst materials and mild transformation conditions to generate and refine a suite of new bioproducts.

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Catalytic depolymerization of lignin via transfer hydrogenation strategy over skeletal CuZnAl catalyst

Cited by 19 publications

References 41 publications

Structural Characteristics–Reactivity Relationships for Catalytic Depolymerization of Lignin into Aromatic Compounds: A Review

Structural Characteristics–Reactivity Relationships for Catalytic Depolymerization of Lignin into Aromatic Compounds: A Review

Catalytic Transfer Hydrogenolysis of Switchgrass Lignin with Ethanol Using Spinel-Type Mixed-Metal Oxide Catalysts Affords Control of the Oxidation State of Isolated Aromatic Products

Catalytic transfer hydrogenolysis of switchgrass lignin with ethanol using spinel-type mixed-metal oxide catalysts affords control of the oxidation state of isolated aromatic products

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