US 5,002,634 AGranted

Method for the delignification of wood pulp utilizing fused ring quinone compounds prepared from lignin or lignin derived substances

AssigneeInstitute of Paper Science and Technology, Inc.

InventorsDonald R. Dimmel, John C. Wozniak

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Abstract

A method for the preparation of a mixture of fused ring quinone type compounds from lignin and lignin derived substances. The mixture of fused ring quinone compounds has been found useful in the wood pulping process as an accelerator in the degradation and separation of wood lignin from the other principal wood constituents, cellulose and hemicellulose.

Claims5

Dependent claims

A method for the delignification of wood pulp utilizing fused ring quinone compounds prepared from lignin and lignin derived substances in pulping liquors resulting from a wood pulping process, the method comprising the steps of:

(a) mixing the lignin and lignin derived substances in a solvent selected from the group consisting of water C.sub.1 -C.sub.4 organic acids, glycols and glycol ethers to form a lignin and lignin derived substances solution;
(b) cooling the solution to a temperature in the range of about -10.degree. C. to about +10.degree. C.;
(c) adding a conjugated organic diene selected from the group consisting of 1,3-butadiene, isoprene, 2,3-demethyl-1,3-butadiene, cyclopentadiene, 1,3-cyclohexadiene and styrene to the solution;
(d) oxidizing the diene containing solution in an inert atmosphere with an oxidizing agent solution selected from the group consisting of potassium nitrodisulfonate, hydrogen peroxide, chromic acid, perhalogenic acid and perhalogenate salt solution;
(e) warming the oxidized diene containing solution to ambient temperature and transferring said solution to a pressure vessel;
(f) adding glacial acetic acid to said solution and heating the resulting reaction mixture after sealing the pressure vessel to a temperature in the range of about 75.degree.-160 C. for a time of about 12-24 hours;
(g) cooling the heated reaction mixture to ambient temperature and venting the vessel;
(h) isolating the reaction products by precipitation on ice and collection by filtration;
(i) reacting the collected product in a C.sub.1 -C.sub.4 carboxylic acid solution with an oxidizing agent selected from the group consisting of potassium nitrodisulfonate, hydrogen peroxide, chromic acid, peroxycarboxylic acids, perhalogenic acid, perhalogenate salt, and thiophenoxide;
(j) isolating the resulting mixture of fused ring quinone compounds by precipitating the product on ice and collecting it by filtration;
and
(k) adding the collected product to an alkali containing wood pulp mixture to accelerate and catalyze the delignification of the wood pulp contained therein.

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Dependencies are inferred from the claim text.

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Abstract

(a) mixing the lignin and lignin derived substances in a solvent selected from the group consisting of water C.sub.1 -C.sub.4 organic acids, glycols and glycol ethers to form a lignin and lignin derived substances solution;
(b) cooling the solution to a temperature in the range of about -10.degree. C. to about +10.degree. C.;
(c) adding a conjugated organic diene selected from the group consisting of 1,3-butadiene, isoprene, 2,3-demethyl-1,3-butadiene, cyclopentadiene, 1,3-cyclohexadiene and styrene to the solution;
(d) oxidizing the diene containing solution in an inert atmosphere with an oxidizing agent solution selected from the group consisting of potassium nitrodisulfonate, hydrogen peroxide, chromic acid, perhalogenic acid and perhalogenate salt solution;
(e) warming the oxidized diene containing solution to ambient temperature and transferring said solution to a pressure vessel;
(f) adding glacial acetic acid to said solution and heating the resulting reaction mixture after sealing the pressure vessel to a temperature in the range of about 75.degree.-160 C. for a time of about 12-24 hours;
(g) cooling the heated reaction mixture to ambient temperature and venting the vessel;
(h) isolating the reaction products by precipitation on ice and collection by filtration;
(i) reacting the collected product in a C.sub.1 -C.sub.4 carboxylic acid solution with an oxidizing agent selected from the group consisting of potassium nitrodisulfonate, hydrogen peroxide, chromic acid, peroxycarboxylic acids, perhalogenic acid, perhalogenate salt, and thiophenoxide;
(j) isolating the resulting mixture of fused ring quinone compounds by precipitating the product on ice and collecting it by filtration;
and
(k) adding the collected product to an alkali containing wood pulp mixture to accelerate and catalyze the delignification of the wood pulp contained therein.

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