The Aerobic Oxidative Cleavage of Lignin to Produce Hydroxyaromatic Benzaldehydes and Carboxylic Acids <i>via</i> Metal/Bromide Catalysts in Acetic Acid/Water Mixtures

Partenheimer, Walt

doi:10.1002/adsc.200800614

Cited by 117 publications

(72 citation statements)

References 25 publications

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“…Catalysts used in lignin oxidation range from metalsupported alumina catalysts like Pd/Al 2 O 3 [107] and Cu-Ni/ Al 2 O 3 [108] to a wide variety of homogenous catalysts [89,109]. Metal salt-based catalysts such as CuO, CuSO 4 , FeCl 3 , and MnSO 4 are the most frequently reported catalysts for lignin oxidation, usually using molecular oxygen as oxidant [33,36,110]. Tab.…”

Section: Catalysts In Lignin Conversionmentioning

confidence: 99%

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

2010

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The structure of lignin suggests that it can be a valuable source of chemicals, particularly phenolics. However, lignin depolymerization with selective bond cleavage is the major challenge for converting it into value-added chemicals. Pyrolysis (thermolysis), gasification, hydrogenolysis, chemical oxidation, and hydrolysis under supercritical conditions are the major thermochemical methods studied with regard to lignin depolymerization. Pyrolytic oil and syngases are the primary products obtained from pyrolysis and gasification. A significant amount of char is also produced during pyrolysis. Thermal treatment in a hydrogen environment seems very promising for converting lignin to liquid fuel and chemicals like phenols, while oxidation can produce phenolic aldehydes. Reaction severity, solvents, and catalysts are the factors of prime importance that control yield and composition of the product. IntroductionThe depleting stocks of fossil fuels and the growing concern over the excessive emission of greenhouse gases have forced researchers to investigate renewable, abundant and comparably cleaner alternatives to liquid fuels and chemicals produced from petroleum [1][2][3]. Biomass appears to be a promising alternative and a renewable source for fuels and chemicals. Significant achievements have already been made in the production of ethanol fuel from biomass, primarily starch and sugarrich components. However, research on second-generation bioethanol is focused on a more abundant [4,5] and often relatively cheap [6][7][8] biomass feedstock known as lignocellulosic biomass. Lignocellulosic biomass consists of three basic components: cellulose, hemicellulose, and lignin. Cellulose is a linear polymer of glucose consisting of parts with crystalline structure and parts with amorphous structure [9], while hemicellulose is an amorphous, heterogeneously branched polymer of pentoses and hexoses, mainly xylose, arabinose, mannose, galactose, and glucose. Lignin is an amorphous and highly branched polymer of phenylpropane units, which can account for up to 40 % of the dry biomass weight [10]. The concept of a biorefinery that integrates processes and technologies for biomass conversion demands efficient utilization of all three components [11]. Most of the biorefinery schemes, however, are focused on utilizing easily convertible fractions while lignin remains relatively underutilized to its potential [11]. The lignocellulosics-to-ethanol process makes use of the cellulose and hemicelluloses, leaving lignin as waste. In addition, pulp and paper refineries also generate huge amounts of lignin. Presently, lignin is being utilized as a low-grade boiler fuel to provide heat and power to the process [3]. However, the chemical structure of lignin suggests that it may be a good source of valuable chemicals if it could be broken into smaller molecular units [7].Several studies have been done to convert lignin to more value-added products. These include attempts to convert lignin to liquid fuel additives and commercially important chem...

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Section: Catalysts In Lignin Conversionmentioning

confidence: 99%

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

2010

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“…The most valuable products from lignin were 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, 4-hydroxy-3-methoxybenzaldehyde (vanillin), 4-hydroxy-3-methoxybenzoic acid (vanillic acid), 4-hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde), and 4-hydroxy-3,5-dimethoxybenzoic acid (syringic acid). By the use of model compounds they demonstrated that (i) the presence of the phenolic functionality on an aromatic ring does inhibit the rate of reaction but that the alkyl group on the ring is still oxidized to the carboxylic acid; (ii) the masking of phenol by acetylation occurs at a reasonable rate in acetic acid; (iii) the alkyl group of the masked phenol is very readily oxidized; (iv) an acetic anhydride/acetic acid mixture is a good oxidation solvent; and (v) that a two-step acetylation/oxidation to the carboxylic acid is feasible [106]. Crestini et al had reported a convenient and efficient application of heterogeneous methyl-rhenium trioxide (MTO) systems for the selective oxidation of lignin model compounds and lignin [36].…”

Section: Lignin To Phenolic Acidsmentioning

confidence: 98%

“…Based on the different structure of the lignin precursors, the oxidation reaction pathways can be divided into three categories. First, p-coumaryl alcohol resembling lignin model compounds to 4-hydrobenzaldehyde [18,26,41,43] and then 4-hydrobenzoic acid [106]; Second, coniferyl alcohol resembling lignin model compounds to vanillin [9,81] and vanillic acid [36]; Third, sinapyl alcohol resembling lignin model compounds to syringaldehyde and syringic acid.…”

Section: Lignin To Phenolic Acidsmentioning

confidence: 99%

Catalytic Conversion of Lignocellulosic Biomass to Value-Added Organic Acids in Aqueous Media

Lin

Liu

et al. 2014

Green Chemistry and Sustainable Technology

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The transition from today's fossil-based economy to a sustainable economy based on renewable biomass is driven by the concern of climate change and anticipation of dwindling fossil resources. Although biofuels are the central theme of the transition, biomass resources cannot completely replace petroleum. It is projected that biofuels can only supply up to 30 % of today's transportation fuel market even if all available domestic biomass resources are used for the production of liquid fuels. Therefore, transformation of biomass into high-value-added chemicals is advantageous to secure optimal use of the abundant, but limited, biomass resources from the economical and ecological perspective. Industry is increasingly considering bio-based chemical production as an attractive area for investment. The potential for chemical and polymer production from biomass is substantial. The US Department of Energy recently issued a report which listed 12 chemical building blocks considered as potential building blocks for the future. Organic acids (e.g., succinic, lactic, levulinic acid, etc.) are among the widely spread ''platform-molecules,'' which may be further converted into possibly derivable high-value-added chemicals. The transition from a fossil chemical industry to a renewable chemical industry will likewise depend on our ability to focus research and development efforts on the most promising alternatives. In this chapter, we review the emerging technologies on catalytic conversion of biomass to value-added organic acids in aqueous media.

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“…In the limited literature for the degradation of lignin, [18][19][20][21][22][23][24][25] Sergeev and Hartwig 26 made impressive progress on selective hydrogenolysis of lignin model compounds catalyzed by a soluble nickel carbene complex under relatively mild conditions. Kou and co-workers 27 also did nice work on hydrocraking of wood lignin over various noble-metal catalysts through a twostep hydrogenation process, they obtained about 42 wt% C 8 -C 9 alkanes and 10 wt% C 14 -C 18 alkanes from wood lignin.…”

Section: Introductionmentioning

confidence: 99%

One-pot catalytic hydrocracking of raw woody biomass into chemicals over supported carbide catalysts: simultaneous conversion of cellulose, hemicellulose and lignin

Zheng

Wang

et al. 2012

Energy Environ. Sci.

384

327

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Using raw lignocellulosic biomass as feedstock for sustainable production of chemicals is of great significance. Herein, we report the direct catalytic conversion of raw woody biomass into two groups of chemicals over a carbon supported Ni-W 2 C catalyst. The carbohydrate fraction in the woody biomass, i.e., cellulose and hemicellulose, were converted to ethylene glycol and other diols with a total yield of up to 75.6% (based on the amount of cellulose & hemicellulose), while the lignin component was converted selectively into monophenols with a yield of 46.5% (based on lignin). It was found that the chemical compositions and structures of different sources of lignocellulose exerted notable influence on the catalytic activity. The employment of small molecule alcohol as a solvent could increase the yields of phenols due to the high solubilities of lignin and hydrogen. Remarkably, synergistic effect in Ni-W 2 C/ AC existed not only in the conversion of carbohydrate fractions, but also in lignin component degradation. For this reason, the cheap Ni-W 2 C/AC exhibited competitive activity in comparison with noble metal catalysts for the degradation of the wood lignin. Furthermore, the catalyst could be reused at least three times without the loss of activity. The direct conversion of the untreated lignocellulose drives our technology nearer to large-scale application for cost-efficient production of chemicals from biomass.

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The Aerobic Oxidative Cleavage of Lignin to Produce Hydroxyaromatic Benzaldehydes and Carboxylic Acids via Metal/Bromide Catalysts in Acetic Acid/Water Mixtures

Cited by 117 publications

References 25 publications

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

Catalytic Conversion of Lignocellulosic Biomass to Value-Added Organic Acids in Aqueous Media

One-pot catalytic hydrocracking of raw woody biomass into chemicals over supported carbide catalysts: simultaneous conversion of cellulose, hemicellulose and lignin

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