Catalytic disassembly of an organosolv lignin via hydrogen transfer from supercritical methanol

Barta, Katalin; Matson, Theodore D.; Fettig, Makayla L.; Scott, Susannah L.; Iretskii, Alexei V.; Ford, Peter C.

doi:10.1039/c0gc00181c

Cited by 324 publications

(312 citation statements)

References 22 publications

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“…Alcohol has been employed as a hydrogen source in several studies. [61][62][63] In our study, taking methanol for example, summing up of the total methanol consumption in converting 2.0 g of birch lignin into monomeric phenolics requires about 80 mg of methanol, which is only 0.3% of added methanol in the reaction. Different catalysts with alternation of supports and active components were evaluated in the LDP reaction (Table 1, entries [13][14][15][16].…”

Section: Resultsmentioning

confidence: 99%

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Song

Wang

Cai

et al. 2013

Energy Environ. Sci.

816

661

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Valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts has been studied. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Alcohols, such as methanol, ethanol and ethylene glycol, are suitable solvents for lignin conversion. Analyses with MALDI-TOF and NMR show that birch lignin is first fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. The presence of gaseous H 2 has no effect on lignin conversion, indicating that alcohols provide active hydrogen species, which is further confirmed by isotopic tracing experiments. Catalysts are recycled by magnetic separation and can be reused four times without losing activity. The mechanistic insights from this work could be helpful in understanding native lignin conversion and the formation of monomeric phenolics via reductive depolymerization. Broader contextNature efficiently synthesizes aromatic structures and deposits them as lignin in plants. Incorporation of catalytic technologies into lignin conversion is a possible option for valorizing the feedstock as a renewable raw material for aromatic chemical production. Use of heterogeneous catalysts facilitates separation and recycling, and has attracted great attention. However, the detailed chemistry between solid catalysts and solid feedstocks still remains unknown because of mass transfer limitations. Herein we report the valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Analysis results show that birch lignin is rst fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. This study will greatly contribute to the understanding of the lignin depolymerization reaction and will be interesting for other biomass conversion.

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Section: Resultsmentioning

confidence: 99%

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Song

Wang

Cai

et al. 2013

Energy Environ. Sci.

816

661

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“…34 However, two issues were of concern. The first was whether a process involving the heterogeneous catalyst (Cudoped PMO) and a heterogeneous substrate would indeed be effective.…”

Section: ■ Quantitative Conversion Of Organosolv Ligninmentioning

confidence: 99%

“…34,35 Similarly while scMeOH is known to partially solubilize wood, char formation occurs in the absence of catalyst. This undesired byproduct is absent in nearly every case for the reactions with the Cu-doped porous metal oxides described here.…”

Section: Mechanistic Considerationsmentioning

confidence: 99%

Catalytic Conversion of Nonfood Woody Biomass Solids to Organic Liquids

2014

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CONSPECTUS: This Account outlines recent efforts in our laboratories addressing a fundamental challenge of sustainability chemistry, the effective utilization of biomass for production of chemicals and fuels. Efficient methods for converting renewable biomass solids to chemicals and liquid fuels would reduce society's dependence on nonrenewable petroleum resources while easing the atmospheric carbon dioxide burden. The major nonfood component of biomass is lignocellulose, a matrix of the biopolymers cellulose, hemicellulose, and lignin. New approaches are needed to effect facile conversion of lignocellulose solids to liquid fuels and to other chemical precursors without the formation of intractable side products and with sufficient specificity to give economically sustainable product streams. We have devised a novel catalytic system whereby the renewable feedstocks cellulose, organosolv lignin, and even lignocellulose composites such as sawdust are transformed into organic liquids. The reaction medium is supercritical methanol (sc-MeOH), while the catalyst is a copper-doped porous metal oxide (PMO) prepared from inexpensive, Earth-abundant starting materials. This transformation occurs in a single stage reactor operating at 300−320°C and 160−220 bar. The reducing equivalents for these transformations are derived by the reforming of MeOH (to H 2 and CO), which thereby serves as a "liquid syngas" in the present case. Water generated by deoxygenation processes is quickly removed by the water−gas shift reaction. The Cu-doped PMO serves multiple purposes, catalyzing substrate hydrogenolysis and hydrogenation as well as the methanol reforming and shift reactions. This one-pot "UCSB process" is quantitative, giving little or no biochar residual. Provided is an overview of these catalysis studies beginning with reactions of the model compound dihydrobenzofuran that help define the key processes occurring. The initial step is phenyl−ether bond hydrogenolysis, and this is followed by aromatic ring hydrogenation. The complete catalytic disassembly of the more complex organosolv lignin to monomeric units, largely propyl-cyclohexanol derivatives is then described. Operational indices based on 1 H NMR analysis are also presented that facilitate holistic evaluation of these product streams that within several hours consist largely of propyl-cyclohexanol derivatives. Lastly, we describe the application of this methodology with several types of wood (pine sawdust, etc.) and with cellulose fibers. The product distribution, albeit still complex, displays unprecedented selectivity toward the production of aliphatic alcohols and methylated derivatives thereof. These observations clearly indicate that the Cu-doped solid metal oxide catalyst combined with sc-MeOH is capable of breaking down the complex biomass derived substrates to markedly deoxygenated monomeric units with increased hydrogen content. Possible implementations of this promising system on a larger scale are discussed.

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“…At present, industrial processes are limited to vanillin and "kraft lignin" (about 60 kt/year) manufacture but, the research on the sustainable production of chemicals from lignin has developed rapidly in the last years [48][49][50][51][52]. To this regard, one of the major challenges is the low cost-effective catalytic depolymerization of lignin preserving its aromatic nature [53][54][55][56][57][58][59][60][61][62][63][64][65].…”

Section: Introductionmentioning

confidence: 99%

Upgrading Lignocellulosic Biomasses: Hydrogenolysis of Platform Derived Molecules Promoted by Heterogeneous Pd-Fe Catalysts

et al. 2017

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Abstract:This review provides an overview of heterogeneous bimetallic Pd-Fe catalysts in the C-C and C-O cleavage of platform molecules such as C2-C6 polyols, furfural, phenol derivatives and aromatic ethers that are all easily obtainable from renewable cellulose, hemicellulose and lignin (the major components of lignocellulosic biomasses). The interaction between palladium and iron affords bimetallic Pd-Fe sites (ensemble or alloy) that were found to be very active in several sustainable reactions including hydrogenolysis, catalytic transfer hydrogenolysis (CTH) and aqueous phase reforming (APR) that will be highlighted. This contribution concentrates also on the different synthetic strategies (incipient wetness impregnation, deposition-precipitaion, co-precipitaion) adopted for the preparation of heterogeneous Pd-Fe systems as well as on the main characterization techniques used (XRD, TEM, H 2 -TPR, XPS and EXAFS) in order to elucidate the key factors that influence the unique catalytic performances observed.

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Catalytic disassembly of an organosolv lignin via hydrogen transfer from supercritical methanol

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Cited by 324 publications

References 22 publications

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Catalytic Conversion of Nonfood Woody Biomass Solids to Organic Liquids

Upgrading Lignocellulosic Biomasses: Hydrogenolysis of Platform Derived Molecules Promoted by Heterogeneous Pd-Fe Catalysts

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