Combustion properties of thermochemically treated softwood and hardwood kraft black liquors

Alén, Raimo; Louhelainen, Jarmo

doi:10.3183/npprj-2003-18-02-p150-157

Cited by 2 publications

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“…The aliphatic carboxylic acids isolated from kraft BL are mainly composed of volatile acids (formic acid and acetic acid), hydroxy acids with 2–4 carbon atoms (mainly glycolic acid, lactic acid, 2-hydroxybutanoic acid, and 2,5-dihydroxypentanoic acid), and isosaccharinic acids with 5–6 carbon atoms (mainly gluco- and xylo-isosaccharinic acids). 41 , 59 Some of these predominant carboxylic acids in kraft BL have been upgraded. For example, the utilization of the volatile components of the carboxylic acids (formic and acetic) via pathways like ketonization and catalytic transfer hydrogenation is well established in the literature.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Upgrading of a Mixed Hydroxy Acid Feedstock Derived from Kraft Black Liquor

Ojelade,

Fu,

Nair

et al. 2024

ACS Sustainable Chem. Eng.

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Lignocellulosic feedstocks are widely studied for sustainable liquid fuel and chemical production. The pulp and paper industry generates large amounts of kraft black liquor (BL) from which a high volume of hydroxy acids (HAs) can be separated for further catalytic processing. Here, we explore the catalytic upgrading of HAs, including the conversion of (1) a model HA, gluconic acid; (2) a model mixture of HAs, and (3) a real mixture of HAs derived from kraft BL on M/Nb2O5 (M = Pd, Pt, Rh, and Ru). The hydrodeoxygenation of model gluconic acid reveals that “volatile” carboxylic acids (mainly C2 and C3), levulinic acid, and cyclic esters are significant products over all the catalysts, with Pd/Nb2O5 showing superior activity and selectivity toward valuable intermediates. The model mixture of HAs shows a wide range of reactivity over the supported metal catalyst, with the product selectivity strongly correlating to reaction temperature. Utilizing a 0.25% Pd/Nb2O5 catalyst, a real mixture of HAs derived from kraft BL is successfully dehydroxylated to produce a mixture rich in C3–C8 carboxylic acids that may be amenable for further upgrading, e.g., catalytically to ketones with high carbon chain lengths. Despite the feedstock complexity, we selectively cleaved the C–OH bonds of HAs, while successfully preserving most of the −COOH groups and minimizing C–C and CO bond scission reactions under the operating conditions tested. The BL-derived HA stream is thus proposed to be a suitable platform for producing mixed carboxylic acid products from an overoxygenated byproduct feed.

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Section: Resultsmentioning

confidence: 99%

Catalytic Upgrading of a Mixed Hydroxy Acid Feedstock Derived from Kraft Black Liquor

Ojelade,

Fu,

Nair

et al. 2024

ACS Sustainable Chem. Eng.

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Characterization of black liquors from kraft pulping of first-thinning Scots pine (Pinus sylvestris L.)

Rautiainen

Alén

2010

Holzforschung

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Formation of hydroxy acids and soluble lignin fragments was investigated during conventional kraft pulping of first-thinning Scots pine (Pinus sylvestris L.) stem wood and its long-fiber outer part and short-fiber inner part. The results indicate that there are characteristic differences in the formation of hydroxy acids in these specific tissues, due to the slightly different contents of cellulose, hemicelluloses, and lignin. Notable are the differences in the formation of xylan-derived acids (2-hydroxybutanoic and xyloisosaccharinic acids) and glucomannan- and cellulose-derived acids (3,4-dideoxy-pentonic and glucoisosaccharinic acids). In contrast, no significant differences were found in the average molecular masses of the dissolved lignins in these black liquors. Finally, the black liquor from the outer part of first-thinning pine was shown to have similar properties as the black liquor from the reference mature wood material.

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Combustion properties of thermochemically treated softwood and hardwood kraft black liquors

Cited by 2 publications

References 0 publications

Catalytic Upgrading of a Mixed Hydroxy Acid Feedstock Derived from Kraft Black Liquor

Catalytic Upgrading of a Mixed Hydroxy Acid Feedstock Derived from Kraft Black Liquor

Characterization of black liquors from kraft pulping of first-thinning Scots pine (Pinus sylvestris L.)

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