# US 10,767,307 B2 · Method for catalytic oxidation of cellulose and method for making a cellulose product > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,767,307 B2 - Document ID: US10767307B2 - Status: Granted - Kind: B2 - Application number: 14/907,905 - Filed: 2014-07-29 - Published: 2016-06-09 - Granted: 2020-09-08 - Earliest claimed: 2013-07-29 - Assignees: Upm-Kymmene Corporation - Applicants: UPM-Kymmene Corporation - Inventors: Timo Pääkkönen; Tapani Vuorinen; Markus Nuopponen - Web page: https://patentgrep.com/patent/US10767307B2 ## CPC - D21C 9/005: {organic compounds} - C08B 15/02: Oxycellulose; Hydrocellulose; {Cellulosehydrate, e.g. microcrystalline cellulose} - C08B 15/04: Carboxycellulose, e.g. prepared by oxidation with nitrogen dioxide - D21C 9/007: {by mechanical or physical means} - D21H 11/18: Highly hydrated, swollen or fibrillatable fibres - D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR - C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21) - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR ## Abstract A method for catalytic oxidation of cellulose using a heterocyclic nitroxyl radical as catalyst, main oxidant acting as oxygen source, and an activator of the heterocyclic nitroxyl radical, comprises—a preliminary activation step of the heterocyclic nitroxyl radical with hypochlorite to activated catalyst, and after the preliminary activation step, a cellulose oxidation step using the activated catalyst and hypochlorite as the main oxidant to oxidize cellulose. In the cellulose oxidation step, fibrous starting material is subjected to the oxidation to oxidize the cellulose, whereafter the oxidized fibrous raw material is disintegrated to nanofibrillar cellulose (NFC). ## Claims ### Claim 1 A method for catalytic oxidation of cellulose using a heterocyclic nitroxyl radical as catalyst, main oxidant acting as oxygen source, and an activator of the heterocyclic nitroxyl radical, characterized in that the method comprises (a) a separate preliminary activation step of the heterocyclic nitroxyl radical consisting of activating the heterocyclic nitroxyl radical catalyst with hypochlorite in a reaction medium in the absence of cellulose and adjusting the pH with an acid to a pH of 6 to 8; and (b) a cellulose oxidation step using the activated catalyst and main oxidant to oxidize primary hydroxyl groups of cellulose in a reaction medium comprising the activated heterocyclic nitroxyl catalyst, cellulose, and main oxidant at a pH higher than the pH of the preliminary activation step; and wherein hypochlorite is used as the main oxidant in the cellulose oxidation step. ### Claim 2 (depends on 1) The method according to claim 1, wherein in the cellulose oxidation step, the cellulose is oxidized catalytically using the main oxidant and the activated catalyst at a pH of 7-10. ### Claim 3 (depends on 1) The method according to claim 1, wherein the pulp initial consistency in the cellulose oxidation step is above 6%. ### Claim 4 (depends on 1) The method according to claim 1, wherein in the cellulose oxidation step, the cellulose is oxidized in the absence of bromide or iodide. ### Claim 5 (depends on 1) The method according to claim 1, wherein after the cellulose oxidation step, aldehyde groups in the cellulose are oxidized to carboxylic groups in a second, complementary oxidation step. ### Claim 6 (depends on 1) The method according to claim 1, wherein the cellulose is oxidized to the level of 0.5-1.4 mmol COOH/g pulp. ### Claim 7 (depends on 1) The method according to claim 1, wherein the cellulose subjected to catalytic oxidation in the cellulose oxidation step is the cellulose in fibrous raw material. ### Claim 8 (depends on 1) The method according to claim 1, wherein the pulp initial consistency in the cellulose oxidation step is above 6% and at the most 12%. ### Claim 9 (depends on 1) The method according to claim 1, wherein the pulp initial consistency in the cellulose oxidation step is 8-12%. ### Claim 10 (depends on 1) The method according to claim 1, wherein the cellulose is oxidized to the level of 0.5-1.1 mmol COOH/g pulp. ### Claim 11 (depends on 1) The method according to claim 1, wherein the cellulose is oxidized to the level of 0.6-0.95 mmol COOH/g pulp. ### Claim 12 (depends on 1) The method according to claim 1, wherein the cellulose subjected to catalytic oxidation in the cellulose oxidation step is the cellulose in fibers obtained from plant material. ### Claim 13 (depends on 1) The method of claim 1, wherein the primary hydroxyl groups of the cellulose are oxidized to aldehydes in the cellulose oxidation step. ### Claim 14 (depends on 1) The method of claim 1, wherein the primary hydroxyl groups of the cellulose are oxidized to aldehydes and carboxylic acids in the cellulose oxidation step. ### Claim 15 (depends on 1) The method of claim 1, wherein the temperature of the oxidation step is controlled to be in a range of 26° C. to 35° C. ### Claim 16 (depends on 1) The method according to claim 1, wherein the pH of the preliminary activation step is adjusted to a pH of 6.5-7.5 with an acid, and the pH of the cellulose oxidation step is 8-9.5. ### Claim 17 (depends on 1) The method according to claim 1, comprising adjusting the pH of the cellulose oxidation step to a pH higher than the pH of the preliminary activation step by adding an alkaline pH adjusting agent. ### Claim 18 (depends on 1) The method according to claim 1, wherein the hypochlorite is used in the preliminary activation step in a stoichiometric ratio of hypochlorite:heterocyclic nitroxyl radical catalyst of greater than 1:1 to 3:1. ### Claim 19 (depends on 1) A method for making a cellulose product, comprising (a) subjecting fibrous starting material to catalytic oxidation in a cellulose oxidation step according to the method according to claim 1 to obtain oxidized fibrous material, and (b) disintegrating the oxidized fibrous raw material. ### Claim 20 (depends on 19) The method according to claim 19, wherein the oxidized fibrous raw material is disintegrated to nanofibrillar cellulose (NFC) having shear-thinning behavior, with zero shear viscosity in the range of 1,000 to 100,000 Pa·s, and with a yield stress in the range of 1 to 50 Pa, determined by rotational rheometer at a consistency of 0.5 wt % in aqueous medium. ### Claim 21 (depends on 20) The method according to claim 20, wherein the nanofibrillar cellulose is essentially crystalline with degree of crystallinity of at least 55%, being made of plant material. ### Claim 22 (depends on 19) The method according to claim 19, wherein the oxidized fibrous raw material is disintegrated to nanofibrillar cellulose (NFC) having shear-thinning behavior, with zero shear viscosity in the range of 5,000 to 50,000 Pa·s, and with a yield stress in the range of 3 to 15 Pa, determined by rotational rheometer at a consistency of 0.5 wt % in aqueous medium. ### Claim 23 (depends on 19) The method of claim 19, wherein the fibrous starting material is fibers obtained from plant material.