Production of phenol compounds by alkaline treatment of technical hydrolysis lignin and wood biomass

Nenkova, S.; Васильева, Т. В.; Stanulov, K.

doi:10.1007/s10600-008-9009-z

Cited by 49 publications

(28 citation statements)

References 10 publications

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“…Zeolite H-ZSM-5 produced more aromatic hydrocarbons while amorphous silica-alumina catalysts favored aliphatic hydrocarbons [100]. Base catalysts such as KOH and NaOH have been found effective in lignin hydrolysis, and the process employing them is known as BCD [68,72,101,102].…”

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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“…However, chemical methods for such conversions of lignocellulose materials have been very elusive. Characteristic lignin units are methoxylated and hydroxylated 4-propylphenols coupled as ethers and occasionally cross-linked with carboncarbon bonds.[2] Possible strategies for chemical disassembly include hydrolysis or hydrogenolysis of ether linkages, [3][4][5][6][7] and oxidative CÀC bond cleavage in analogy to degradation by white rot fungus. [8,9] The advantage of hydrogenolysis is the increased fuel value from adding H 2 equivalents, which in principle may be obtained by reforming biomass-derived alcohols such as glycerol or cellulose.…”

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confidence: 99%

Hydrogen Transfer from Supercritical Methanol over a Solid Base Catalyst: A Model for Lignin Depolymerization

et al. 2009

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A (super)critical transfer: The consecutive hydrogenolysis and hydrogenation of the lignin model compound dihydrobenzofuran was studied in supercritical methanolic solutions using porous metal oxide catalysts. These catalysts promote H(2) production from methanol followed by hydrogenolysis of the ether linkages and reduction of the aromatic rings, leading principally to a mixture of cyclohexanols.

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“…For example, treatment of lignin with 5% NaOH in water at the relatively low temperature of 180°C over four to six hours produced low molecular weight products including guaiacol, syringol, benzaldehyde and vanillin [291]. Some degree of lignin hydrolysis is seen under surprisingly gentle conditions, with up to 20% of water soluble products reported on treatment at pH 12.0 and 25°C, but this is probably not associated with any significant amount of ß-O-5 bond scission [292].…”

Section: Alkaline Hydrolysismentioning

confidence: 99%