Experimental evaluation and continuous catalytic process for fine aldehyde production from lignin

Sales, Fernando G.; Maranhão, Laísse C.A.; Filho, Nelson M. Lima; Abreu, César Augusto Moraes de

doi:10.1016/j.ces.2007.02.018

Cited by 95 publications

(78 citation statements)

References 11 publications

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“…Catalysts have been used in both acidic and alkaline oxidation to increase the yield of aldehydes [33,80]. 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].…”

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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“…Various types of catalysts from expensive noble metals [20][21][22] to inexpensive metal ions such as iron, copper, and cobalt have been extensively studied [23][24][25][26][27] for a lignin catalytic wet oxidation process. In general, the lignin conversion rate and the yield of aromatic aldehydes are enhanced significantly in catalytic processes compared with non-catalytic processes [28].…”

Section: Introductionmentioning

confidence: 99%

Alkaline Partial Wet Oxidation of Lignin for the Production of Carboxylic Acids

et al. 2015

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The production of carboxylic acids by partial wet oxidation of alkali lignin was studied experimentally. The factors influencing the different types of products, their yields and concentrations were investigated. Formic, acetic, succinic, oxalic, and glutaconic acid were the main identified products. Both the temperature and oxygen partial pressure are shown to have direct effects on the product yields whereas the lignin concentration has an indirect effect. At low lignin concentrations, the yield of products was relatively high. However, at higher concentrations, the yield decreased. By measuring the lignin molecular weight distributions, it is shown that this decrease is linked to repolymerization/condensation reactions of lignin fragments which compete with oxidative lignin depolymerization.

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“…New methods that can process lignin into value-added aromatic chemicals are highly desirable. (Sales et al, 2007;Marshall and Alaimo, 2010;Zakzeski et al, 2010;Murat Sen et al, 2012; Ben et al, 2013;Gao et al, 2014) Lignin consists of interlinked arylpropane units with various functional groups like ethers, methoxy and hydroxyl groups, as well as C-C linkages. The most abundant lignin linkage is the β-O-4 linkage with 45-50% occurrence in softwood and even more than 60% in hardwood.…”

Section: Introductionmentioning

confidence: 99%

Base promoted hydrogenolysis of lignin model compounds and organosolv lignin over metal catalysts in water

Konnerth

Zhang

et al. 2015

Chemical Engineering Science

159

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The first systematic study of base promotional effect in lignin hydrogenolysis.. Lignin hydrogenolysis into aromatics was carried out in pure water under mild conditions. The yield for monomeric aromatic compounds from lignin increased ca. 100% in the presence of base. Base promotional effect was observed over Ru (a typical noble metal) and Ni (a typical non-noble metal) catalysts. Ru catalyst (a stable catalyst over a wide pH range), from which a significantly increased selectivity towards monomeric compounds was observed in the presence of base. This promotional effect was studied in detail over bimetallic Ni 7 Au 3 nanoparticles. Addition of a strong base such as NaOH significantly enhanced the activity and selectivity for C-O bond hydrogenolysis over undesired hydrogenation reactions, not only in lignin model compounds but also in real lignin conversion. Notably, the yield for monomeric aromatic compounds from lignin over Ni 7 Au 3 catalyst increased ca. 100% after adding NaOH as a promoter, under the same reaction conditions. Mechanistic study suggest that addition of base significantly reduced the benzene ring hydrogenation activity of the metal catalysts. The effect of adding different bases over various metal catalysts were also investigated.

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Experimental evaluation and continuous catalytic process for fine aldehyde production from lignin

Cited by 95 publications

References 11 publications

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

Lignin Depolymerization and Conversion: A Review of Thermochemical Methods

Alkaline Partial Wet Oxidation of Lignin for the Production of Carboxylic Acids

Base promoted hydrogenolysis of lignin model compounds and organosolv lignin over metal catalysts in water

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