EP0325890B1 - Process for treating lignin containing cellulose pulp with ozone - Google Patents
Process for treating lignin containing cellulose pulp with ozone Download PDFInfo
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- EP0325890B1 EP0325890B1 EP88810034A EP88810034A EP0325890B1 EP 0325890 B1 EP0325890 B1 EP 0325890B1 EP 88810034 A EP88810034 A EP 88810034A EP 88810034 A EP88810034 A EP 88810034A EP 0325890 B1 EP0325890 B1 EP 0325890B1
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- Prior art keywords
- ozone
- fatty acid
- pulp
- lignin
- acid
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
- D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Definitions
- the invention relates to a method for treating lignin-containing cellulose mass, i.e. Ligno cellulose or pulp.
- lignin-containing cellulose mass i.e. Ligno cellulose or pulp.
- “Lignocelluloses” are understood here to mean the macromolecular substances which, in addition to cellulose, also contain hemicelluloses and lignin, such as e.g. is the case with wood.
- the removal of lignin from cellulose or wood is also referred to as "delignification”.
- the raw material consisting of wood or woody annual plants, usually in a mechanically crushed state, is chemically digested.
- acetic acid is used instead of the conventional digestion chemicals based on sulfur compounds, which are problematic for disposal. This method, also known as the acetosol method, offers a significant reduction in environmental pollution compared to conventional methods.
- the pulps obtained from the Acetosolv digestion can still contain up to 4% residual lignin, which usually has to be removed by a bleaching treatment.
- hydrogen peroxide is added as the bleaching agent, which combines with the acetic acid to form peracetic acid, which is considered a selective lignin oxidizing agent.
- this bleaching has so far only led to satisfactory degrees of whiteness with hardwood pulp, and even then only with a relatively high consumption of hydrogen peroxide:
- several bleaching stages with bleaches containing chlorine are used to achieve high degrees of whiteness. As a result, chlorine-containing organic compounds are formed in the waste liquors, which lead to serious wastewater problems.
- ozone In addition to hydrogen peroxide and oxygen, ozone has also been proposed as a chlorine-free bleach. Despite great efforts, however, ozone has not yet been used technically as a bleaching agent, because the reaction of ozone in water with hydroxyl ions generates hydroxyl radicals, which break down the cellulose molecules and thus lower the strength properties of the pulp and prejudice the use of ozone as Have established bleach in the pulp production.
- ABIPC 6233 (Volume 54, No. 6, December 1983) describes a further investigation of the effect of sulfuric acid, acetic acid, chemical additives and process variables on the ozone bleaching of sulfate cellulose. Also in this publication, there are no indications of the suitability of concentrated C1 ⁇ 3 fatty acids or acetic acid as a selective solvent or extraction agent for oxidized lignin.
- the inventive method for the treatment of cellulose mass with ozone has the features indicated in the characterizing part of claim 1.
- ozone concentration is increased and, on the other hand, side reactions due to ozone decomposition products can be reduced.
- low fatty acids react as radical scavengers with OH radicals and can thus prevent these very unselective radicals from attacking cellulose.
- the ozone itself does not have a radical effect, but preferably electrophilic, as a result of which the lignin is selectively attacked and broken down into soluble products.
- ozone in low fatty acids increases its effectiveness as a bleaching agent and thus reduces ozone consumption, which is of fundamental importance for technical use.
- acetic acid is a better solvent for lignin than water, while the reverse is true for cellulose, which further increases the selectivity of ozone as a delignifying agent.
- cellulose mass in the claims and the description denotes all masses (including starting materials) which are suitable for the production of cellulose or cellulose and cellulose (here includes both ⁇ -cellulose and the hemicelluloses sometimes referred to as ⁇ - or ⁇ -cellulose). as well as lignin included.
- acetic acid and propionic acid are suitable as C1 ⁇ 3 fatty acids.
- Acetic acid is preferred.
- Mixtures of such acids with one another and / or with water in limited proportions are also suitable, the water content of the fatty acid, the fatty acid mixture or the preferred acetic acids being less than 50% by weight, in particular less than 30% by weight, and usually 1 to 10% by weight. % is.
- a low water content of e.g. 5 to 10% by weight, i.e. a 90 to 95% acetic acid is particularly preferred.
- Ozone obtainable with conventional generators is contained in the gas phase which surrounds the mixture combined with fatty acid, for example consisting of 2 to 50% by weight cellulose mass and 98 to 50% by weight fatty acid.
- the interaction between the cellulose mass / fatty acid mixture on the one hand and the gas phase or the ozone contained therein on the other hand can be influenced in particular by movement or / and the amount of ozone present and / or the temperature. Through movement, both the mixing intensity and the distribution of the solid and liquid phases can be influenced or varied and adapted. Conventional mixing devices that are sufficiently resistant to the components can be used for this purpose; Mixers with a pronounced shear effect on the mix are not preferred.
- the amount of ozone present in the gas phase can be influenced by the gas pressure and / or the ozone concentration in the gas phase.
- a gas phase which mainly consists of air.
- the ozone concentration of a gas phase suitable for the process and consisting predominantly of air or oxygen under normal or slight excess pressure is 0.1 to 10%, generally 1 to 3%. These values are based on the gas volume.
- amounts of ozone of 1 to 2% by weight, but also even higher concentrations, can be used without adverse effects for the pulp obtained when working at the preferred temperatures of 0 to 30 ° C.
- the working temperature (measured in the cellulose mass or the gas phase) is below 100 ° C, in particular below 50 ° C.
- the process according to the invention offers particular advantages when it is used as a delignification stage for pulp bleaching, in which the starting material, in particular wood, is digested with acetic acid, for example by the process described in DE-A-3 445 132.
- the starting material in particular wood
- acetic acid for example by the process described in DE-A-3 445 132.
- coniferous wood eg spruce wood
- this offers considerable advantages because the peroxide consumption is then comparatively high in the known treatment with peroxides.
- kappa values or kappa numbers given here were determined using the method described in Leaflet IV / 37/80 of the Technical Committee for Chemical Pulp and Paper Testing in the Association of Pulp and Paper Chemists and Engineers (BR Germany).
- Whiteness levels in the range just mentioned can also be achieved if bleaching is carried out first with peracetic acid and then with ozone. According to the prior art, whitenesses of over 70% ISO after digestion of acetic acid could only be achieved with relatively large amounts of peroxide. According to the invention, degrees of whiteness of over 80% ISO can be achieved if the pulp is first bleached with ozone in a three-stage bleach (Z), then treated with H2O2 (P) and finally again with ozone (Z) or with a PZP bleaching sequence in the same solvent, ie C1 ⁇ 3 fatty acid or acetic acid.
- the process according to the invention is particularly advantageous as a process stage in a "countercurrent process" which e.g. with known carousel extractors according to the information in the magazine "Wood as raw and material", 44 (1986) 207-212, can be carried out;
- acetic acid with or without ozone is used not only for the final extraction, but as the only lignin solvent.
- operation with a low consistency, preferably 2 to 10% pulp, and ozone concentrations below 2%, preferably 0.5 to 1.5%, is possible.
- the acetic acid should contain less than 50% by weight of water, preferably less than 30% by weight and in particular less than 10% by weight of water.
- an addition of another substance, in particular another C1 ⁇ 3 fatty acid, can also serve, i.e. it can also be used with acetic acid, e.g. Contains 1 to 50 wt.% Propionic and / or formic acid.
- devices known per se are suitable for carrying out the method according to the invention as a separate treatment or as a step in a sequence of treatments or processing operations in the production of cellulose, which devices have at least one chamber or zone for receiving the fat or.
- Cellulose mass containing acetic acid if these devices have devices known per se for treatment with a gas phase containing ozone.
- the parts of the device which come into contact with the mass or the gas phase consist of correspondingly resistant materials, preferably steel alloys.
- the properties e.g. the characteristic values of the pulp obtained, such as tear length, rupture area and tear resistance, were not significantly changed by the treatment with ozone by the process according to the invention; the process according to the invention enables pulp products to be obtained, the quality of which corresponds to that of the conventional pulps obtainable by the sulfate process and is considerably better than that of the products obtained by the sulfite process.
- the invention is illustrated by the following examples.
- the term DP w means the degree of polymerization, based on the weight average molecular weight.
- the ozone treatment can drastically reduce peroxide consumption and still achieve a whiteness of over 70% without the mechanical product properties suffering.
- the fatty acid used for the process according to the invention can be worked up and recirculated in an environmentally friendly manner in a manner known per se, for example by azeotropic distillation.
- the distillation residue containing the lignin can also be worked up in an environmentally friendly manner, for example burned.
- pulp which was made from pine chips (Pinus sylvestris, 45 years) according to the Acetosolv process (Kappa number 24.2), is pressed down to a moisture content of 35% and then mechanically crushed.
- the shredded material is placed in a flask and treated with 1 to 3.3% ozone (0.05 g ozone / min, 0.06 g ozone / liter oxygen). After an exposure time of 10 to 40 minutes, the pulp washed with acetic acid and then with water.
- C1 ⁇ 3 fatty acid mixtures which, for example, are available in the hydrolysis of plant waste and consist of mixtures of acetic acid, propionic acid and formic acid.
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Behandeln von Lignin enthaltender Cellulosemasse, d.h. Ligno cellulosen bzw. Zellstoff (engl.: pulp). Als "Lignocellulosen" werden hier die makromolekularen Substanzen verstanden, die neben Cellulose auch noch Hemicellulosen und Lignin enthalten, wie das z.B. bei Holz der Fall ist. Die Entfernung von Lignin aus Zellstoff oder Holz wird auch als "Delignifizierung" bezeichnet.The invention relates to a method for treating lignin-containing cellulose mass, i.e. Ligno cellulose or pulp. "Lignocelluloses" are understood here to mean the macromolecular substances which, in addition to cellulose, also contain hemicelluloses and lignin, such as e.g. is the case with wood. The removal of lignin from cellulose or wood is also referred to as "delignification".
Zur Gewinnung von Zellstoff wird der aus Holz oder holzigen Einjahrespflanzen bestehende Rohstoff, meist in mechanisch zerkleinertem Zustand, chemisch aufgeschlossen. Bei einem neueren und in DE-A-3 445 132 beschriebenen Verfahren wird anstelle der konventionellen und für die Entsorgung problematischen Aufschlusschemikalien auf Basis von Schwefelverbindungen Essigsäure verwendet. Diese auch als AcetosolvVerfahren bezeichnete Methode bietet eine im Vergleich zu konventionellen Verfahren wesentliche Verminderung der Umweltbelastung.To obtain pulp, the raw material consisting of wood or woody annual plants, usually in a mechanically crushed state, is chemically digested. In a more recent method described in DE-A-3 445 132, acetic acid is used instead of the conventional digestion chemicals based on sulfur compounds, which are problematic for disposal. This method, also known as the acetosol method, offers a significant reduction in environmental pollution compared to conventional methods.
Die beim Acetosolv-Aufschluss gewonnenen Zellstoffe können jedoch je nach Ausgangsmaterial noch bis zu 4% Restlignin enthalten, das meist durch eine Bleichbehandlung entfernt werden muss. Gemäss DE-A-3 445 132 wird als Bleichmittel Wasserstoffperoxid zugegeben, das sich mit der Essigsäure zu Peressigsäure verbindet, die als selektives Ligninoxidationsmittel gilt. Diese Bleiche führt jedoch bisher nur bei Laubholzzellstoff zu befriedigenden Weissgraden, und auch dann nur mit relativ hohem Verbrauch an Wasserstoffperoxid:
Bei den konventionellen Verfahren zur Zellstoffbleiche werden zur Erreichung hoher Weissgrade mehrere Bleichstufen mit chlorhaltigen Bleichmitteln angewendet. Dadurch bilden sich in den Ablaugen chlorhaltige organische Verbindungen, die zu schwerwiegenden Abwasserproblemen führen.However, depending on the starting material, the pulps obtained from the Acetosolv digestion can still contain up to 4% residual lignin, which usually has to be removed by a bleaching treatment. According to DE-A-3 445 132, hydrogen peroxide is added as the bleaching agent, which combines with the acetic acid to form peracetic acid, which is considered a selective lignin oxidizing agent. However, this bleaching has so far only led to satisfactory degrees of whiteness with hardwood pulp, and even then only with a relatively high consumption of hydrogen peroxide:
In the conventional processes for pulp bleaching, several bleaching stages with bleaches containing chlorine are used to achieve high degrees of whiteness. As a result, chlorine-containing organic compounds are formed in the waste liquors, which lead to serious wastewater problems.
Als chlorfreies Bleichmittel ist ausser Wasserstoffperoxid und Sauerstoff auch Ozon vorgeschlagen worden. Trotz grosser Anstrengungen hat aber Ozon als Bleichmittel technisch bisher keine Anwendung gefunden, weil die Reaktion des Ozons in Wasser mit Hydroxylionen Hydroxylradikale erzeugt, die zu einem Abbau der Cellulosemoleküle und damit zur Erniedrigung der Festigkeitseigenschaften des Zellstoffes führen und ein Vorurteil gegen die Verwendung von Ozon als Bleichmittel in der Zellstoffgewinnung begründet haben.In addition to hydrogen peroxide and oxygen, ozone has also been proposed as a chlorine-free bleach. Despite great efforts, however, ozone has not yet been used technically as a bleaching agent, because the reaction of ozone in water with hydroxyl ions generates hydroxyl radicals, which break down the cellulose molecules and thus lower the strength properties of the pulp and prejudice the use of ozone as Have established bleach in the pulp production.
Es wurde nun überraschenderweise gefunden, dass die Delignifizierung von Lignocellulosen mit Ozon, insbesondere bei Zellstoffen mit einem Restligningehalt von unter 5 %, in niederen Fettsäuren, bevorzugt Essigsäure, als Reaktionsmedium sehr viel selektiver verläuft als in Wasser, d. h. daß man zu hohen Weissgraden kommen kann, ohne einen signifikanten Festigkeitsabfall des Zellstoffes zu beobachten.It has now surprisingly been found that the delignification of lignocelluloses with ozone, in particular in the case of pulps with a residual lignin content of less than 5%, is much more selective as a reaction medium in lower fatty acids, preferably acetic acid, than in water, ie that high degrees of whiteness can be achieved without observing a significant decrease in the strength of the pulp.
In der Zusammenfassung Nr. 8417, Abstract Bulletin of the Institute of Paper Chemistry, Band 53, Nr. 8, Februar 1983, Appleton, Wisconsin, US (kurz ABIPC Nr. 8417) wird über eine Untersuchung der Wirkung von organischen Säuren als Kohlehydratschutz beim Bleichen von Sulfatzellstoff (kraft pulp) mit Ozon berichtet. Dabei erwiesen sich von den 27 getesteten Säuren Oxalsäure, Buttersäure und Propionsäure als am wirksamsten. Valeriansäure und Essigsäure waren weniger wirksam, aber noch besser, als die getesteten ungesättigten Säuren, die Keto- und Hydroxysäuren sowie die organischen Säuren. Hierbei wird Ozon in wässriger Lösung eingesetzt, was den Polymerisationsgrad der Cellulose herabsetzt.In Summary No. 8417, Abstract Bulletin of the Institute of Paper Chemistry, Volume 53, No. 8, February 1983, Appleton, Wisconsin, US (ABIPC No. 8417 for short), an investigation of the effect of organic acids as carbohydrate protection in Bleaching of sulfate pulp (kraft pulp) with ozone has been reported. Of the 27 acids tested, oxalic acid, butyric acid and propionic acid proved to be the most effective. Valeric acid and acetic acid were less effective, but even better than the unsaturated acids, keto and hydroxy acids and organic acids tested. Here, ozone is used in aqueous solution, which reduces the degree of polymerization of the cellulose.
Eine Lehre zur Verwendung von konzentrierter C₁₋₃-Fettsäure bzw. Essigsäure als Lösungsmittel zur Abtrennung von Lignin aus Cellulosemasse ist aus diesen Ergebnissen keinesfalls abzuleiten und auch nicht naheliegend, zumal die erst im Zuge der vorliegenden Erfindung festgestellte gute Löslichkeit von oxydiertem Lignin in C₁₋₃-Fettsäure bzw. Essigsäure nicht vorausgesetzt werden konnte.A teaching on the use of concentrated C₁₋₃ fatty acid or acetic acid as a solvent for the separation of lignin from cellulose mass is in no way to be derived from these results and also not obvious, especially since the good solubility of oxidized lignin in C₁₋ found only in the course of the present invention ₃ fatty acid or acetic acid could not be assumed.
Die Zusammenfassung Nr. 38887c der Chemical Abstracts, Band 103, Nr. 6, vom 12.8.85, Columbus, Ohio, US (CA Nr. 38887c) betrifft ebenfalls Untersuchungen über die Wirkung verschiedener Substanzen, auch organischer Säuren, wie insbesondere Oxal-, Propion- und Buttersäure, als Mittel zum Schutz von Sulfatzellstoff beim Bleichen mit Ozon. MeOH-Lösungen von Harnstoff wurden als besonders wirksame Schutzmittel befunden.Summary No. 38887c of Chemical Abstracts, Volume 103, No. 6, August 12, 1985, Columbus, Ohio, US (CA No. 38887c) also relates to studies on the action of various substances, including organic acids, such as especially oxalic acids, Propionic and butyric acid, as a means of protecting sulfate pulp when bleaching with ozone. MeOH solutions of urea have been found to be particularly effective protective agents.
Wiederum ist hieraus kein Hinweis auf die Verwendung konzentrierter C₁₋₃-Fettsäure bzw. Essigsäure als Extraktionsmittel für oxidiertes Lignin abzuleiten.Again, no reference to the use of concentrated C₁₋₃ fatty acid or acetic acid as an extractant for oxidized lignin can be derived from this.
Gemäss ABIPC Nr. 6669 (Band 47, Nr. 6, Dezember 1976) wird die Helligkeit von Zellstoff beim Bleichen mit Ozon verbessert, wenn Essigsäuren, hydroxyethylierte Alkylolamide synthetischer Fettsäuren oder Carbamide zugesetzt werden, um in der Reaktionsmischung einen pH-Wert von 2-7 zu erhalten.According to ABIPC No. 6669 (Volume 47, No. 6, December 1976), the brightness of pulp is improved when bleaching with ozone if acetic acids, hydroxyethylated alkylolamides of synthetic fatty acids or carbamides are added in order to achieve a pH of 2- in the reaction mixture. 7 to get.
Wiederum ist hieraus keinesfalls die Lehre abzuleiten, konzentrierte C₁₋₃-Fettsäure bzw. Essigsäure als Mittel zur selektiven Extraktion von oxydiertem Lignin aus Zellstoff zu verwenden.Again, the teaching of using concentrated C₁₋₃ fatty acid or acetic acid as a means for the selective extraction of oxidized lignin from pulp cannot be derived from this.
In ABIPC 6233 (Band 54, Nr. 6, Dezember 1983) ist eine weitere Untersuchung der Wirkung von Schwefelsäure, Essigsäure, chemischen Additiven und Verfahrensvariablen auf das Ozonbleichen von Sulfatcellulose beschrieben. Auch dieser Publikation sind keine Hinweise auf die Eignung konzentrierter C₁₋₃-Fettsäuren bzw. Essigsäure als selektives Lösungs- bzw. Extraktionsmittel für oxydiertes Lignin zu entnehmen.ABIPC 6233 (Volume 54, No. 6, December 1983) describes a further investigation of the effect of sulfuric acid, acetic acid, chemical additives and process variables on the ozone bleaching of sulfate cellulose. Also in this publication, there are no indications of the suitability of concentrated C₁₋₃ fatty acids or acetic acid as a selective solvent or extraction agent for oxidized lignin.
In US - A - 4'119'486 wird beschrieben, dass Ozon Cellulose und Lignin gleichermassen oxydiert und einen erheblichen Celluloseabbau bewirkt; nach diesem Dokument wird dem wässrigen Zellstoff 0,01 bis 1 % kationisches Tensid zugesetzt, um die Bleichwirkung des Ozons zu verbessern bzw. um die Kappazahl zu senken. Dabei kann vor dem Zusatz des Tensides Säure aus der Gruppe Schwefelsäure, Salzsäure und Essigsäure zugegeben werden, um einen pH-Wert von 1-7 zu erzielen.In US Pat. No. 4,119,486 it is described that ozone oxidizes cellulose and lignin equally and causes a considerable cellulose breakdown; According to this document, 0.01 to 1% cationic surfactant is added to the aqueous pulp in order to improve the bleaching effect of the ozone or to reduce the kappa number. Before the addition of the surfactant, acid from the group of sulfuric acid, hydrochloric acid and acetic acid can be added to achieve a pH of 1-7.
Das erfindungsgemässe Verfahren zur Behandlung von Cellulosemasse mit Ozon hat die im Kennzeichen von Anspruch 1 angegebenen Merkmale.The inventive method for the treatment of cellulose mass with ozone has the features indicated in the characterizing part of claim 1.
Bevorzugte Ausführungsformen des erfindungsgemässen Verfahrens haben die in den Ansprüchen 2-8 genannten Merkmale.Preferred embodiments of the method according to the invention have the features mentioned in claims 2-8.
Ohne die Absicht einer Beschränkung kann angenommen werden, daß die Eignung von Ozon in C₁₋₃-Fettsäure als Bleichmittel für Zellstoff darauf beruht, daß Ozon in solchen Fettsäuren erheblich besser löslich sind, als in Wasser, und die Stabilität des Ozons in niedrigen Fettsäuren vermutlich grösser ist als in Wasser.Without the intention of limitation, it can be assumed that the suitability of ozone in C₁₋₃ fatty acid as a bleaching agent for pulp is based on the fact that ozone is considerably more soluble in such fatty acids than in water, and the stability of the ozone in low fatty acids presumably is larger than in water.
Dadurch kann einerseits die Ozonkonzentration erhöht und können andererseits Nebenreaktionen durch Zerfallprodukte des Ozons verringert werden. Möglicherweise kommt hinzu, dass niedrige Fettsäuren als Radikalfänger mit OH-Radikalen reagieren und damit einen Angriff dieser sehr unselektiv wirkenden Radikale auf die Cellulose verhindern können. Das Ozon selbst wirkt hingegen nicht radikalisch, sondern bevorzugt elektrophil, wodurch das Lignin selektiv angegriffen und zu löslichen Produkten abgebaut wird.On the one hand, this allows the ozone concentration to be increased and, on the other hand, side reactions due to ozone decomposition products can be reduced. In addition, low fatty acids react as radical scavengers with OH radicals and can thus prevent these very unselective radicals from attacking cellulose. The ozone itself, on the other hand, does not have a radical effect, but preferably electrophilic, as a result of which the lignin is selectively attacked and broken down into soluble products.
Durch die vergleichsweise grössere Stabilität des Ozons in niedrigen Fettsäuren wird seine Wirksamkeit als Bleichmittel erhöht und damit der Ozonverbrauch reduziert, was für die technische Anwendung von grundlegender Bedeutung ist. Ferner ist Essigsäure ein besseres Lösungsmittel für Lignin als Wasser, während das Umgekehrte für Cellulose gilt, wodurch die Selektivität des Ozons als Delignifizierungsmittel weiter erhöht wird.The comparatively greater stability of ozone in low fatty acids increases its effectiveness as a bleaching agent and thus reduces ozone consumption, which is of fundamental importance for technical use. Furthermore, acetic acid is a better solvent for lignin than water, while the reverse is true for cellulose, which further increases the selectivity of ozone as a delignifying agent.
Der Begriff "Cellulosemasse" in den Patentansprüchen und der Beschreibung bezeichnet alle Massen (einschliesslich Ausgangsstoffe), die sich zur Zellstoff- oder Cellulosegewinnung eignen und Cellulose (umfasst hier sowohl α-Cellulose als auch die gelegentlich als β- oder γ-Cellulose bezeichneten Hemicellulosen) sowie Lignin enthalten.The term "cellulose mass" in the claims and the description denotes all masses (including starting materials) which are suitable for the production of cellulose or cellulose and cellulose (here includes both α-cellulose and the hemicelluloses sometimes referred to as β- or γ-cellulose). as well as lignin included.
Als C₁₋₃-Fettsäuren sind Ameisensäure, Essigsäure und Propionsäure geeignet. Essigsäure wird bevorzugt. Auch Mischungen solcher Säuren miteinander und/oder mit Wasser in begrenzten Anteilen sind geeignet, wobei der Wasseranteil der Fettsäure, des Fettsäuregemisches oder der bevorzugten Essigsäuren geringer als 50 Gew.%, insbesondere geringer als 30 Gew.% ist und meist 1 bis 10 Gew.% beträgt.Formic acid, acetic acid and propionic acid are suitable as C₁₋₃ fatty acids. Acetic acid is preferred. Mixtures of such acids with one another and / or with water in limited proportions are also suitable, the water content of the fatty acid, the fatty acid mixture or the preferred acetic acids being less than 50% by weight, in particular less than 30% by weight, and usually 1 to 10% by weight. % is.
Ein geringer Wassergehalt von z.B. 5 bis 10 Gew.%, d.h. eine 90 bis 95%ige Essigsäure, wird besonders bevorzugt.A low water content of e.g. 5 to 10% by weight, i.e. a 90 to 95% acetic acid is particularly preferred.
Das z.B. mit üblichen Generatoren erhältliche Ozon ist in der Gasphase enthalten, welche die mit Fettsäure vereinigte, beispielsweise aus 2 bis 50 Gew.% Cellulosemasse und 98 bis 50 Gew.% Fettsäure bestehende Mischung umgibt.That e.g. Ozone obtainable with conventional generators is contained in the gas phase which surrounds the mixture combined with fatty acid, for example consisting of 2 to 50% by weight cellulose mass and 98 to 50% by weight fatty acid.
Die Wechselwirkung zwischen der Cellulosemasse/Fettsäure-Mischung einerseits und der Gasphase bzw. dem darin enthaltenen Ozon andererseits kann insbesondere durch Bewegung oder/und die vorhandene Ozonmenge oder/und die Temperatur beeinflusst werden. Dabei kann durch Bewegung sowohl die Mischintensität als auch die Verteilung der festen und flüssigen Phase beeinflusst bzw. variiert und angepasst werden. Hierzu können übliche Mischeinrichtungen, die gegen die Komponenten ausreichend beständig sind, verwendet werden; Mischer mit ausgeprägter Scherwirkung auf das Mischgut werden aber nicht bevorzugt.The interaction between the cellulose mass / fatty acid mixture on the one hand and the gas phase or the ozone contained therein on the other hand can be influenced in particular by movement or / and the amount of ozone present and / or the temperature. Through movement, both the mixing intensity and the distribution of the solid and liquid phases can be influenced or varied and adapted. Conventional mixing devices that are sufficiently resistant to the components can be used for this purpose; Mixers with a pronounced shear effect on the mix are not preferred.
Die in der Gasphase vorhandene Ozonmenge kann durch den Gasdruck oder/und die Ozonkonzentration in der Gasphase beeinflusst werden. Vorzugsweise wird bei normalem Umgebungsdruck mit einer Gasphase gearbeitet, die überwiegend aus Luft besteht. Es kann aber auch in einer überwiegend aus Sauerstoff bestehenden Gasphase und/oder unter Ueberdruck gearbeitet werden.The amount of ozone present in the gas phase can be influenced by the gas pressure and / or the ozone concentration in the gas phase. At normal ambient pressure, it is preferred to work with a gas phase which mainly consists of air. However, it is also possible to work in a gas phase consisting predominantly of oxygen and / or under excess pressure.
Die Ozonkonzentration einer für das Verfahren geeigneten und überwiegend aus Luft oder Sauerstoff bestehenden Gasphase unter normalem oder schwachem Ueberdruck beträgt 0,1 bis 10%, in der Regel 1 bis 3%. Diese Werte sind bezogen auf das Gasvolumen. In Bezug auf das Gewicht der vorhandenen Cellulosemasse können Ozonmengen von 1 bis 2 Gew.%, aber auch noch höhere Konzentrationen ohne nachteilige Wirkungen für den erhaltenen Zellstoff zur Anwendung kommen, wenn bei den bevorzugten Temperaturen von 0 bis 30°C gearbeitet wird. Allgemein liegt die Arbeitstemperatur (gemessen in der Cellulosemasse oder der Gasphase) unter 100°C, insbesondere unter 50°C.The ozone concentration of a gas phase suitable for the process and consisting predominantly of air or oxygen under normal or slight excess pressure is 0.1 to 10%, generally 1 to 3%. These values are based on the gas volume. With regard to the weight of the cellulose mass present, amounts of ozone of 1 to 2% by weight, but also even higher concentrations, can be used without adverse effects for the pulp obtained when working at the preferred temperatures of 0 to 30 ° C. In general, the working temperature (measured in the cellulose mass or the gas phase) is below 100 ° C, in particular below 50 ° C.
Besondere Vorteile bietet das erfindungsgemässe Verfahren, wenn es als Delignifizierungsstufe zur Zellstoffbleiche eingesetzt wird, bei welchem das Ausgangsmaterial, insbesondere Holz, mit Essigsäure z.B. nach dem in DE-A-3 445 132 beschriebenen Verfahren aufgeschlossen wird. Insbesondere bei Verwendung von Nadelhölzern (z.B. Fichtenholz) bietet dies beachtliche Vorteile, weil dann in der bekannten Behandlung mit Peroxiden der Verbrauch an Peroxid vergleichsweise hoch ist.The process according to the invention offers particular advantages when it is used as a delignification stage for pulp bleaching, in which the starting material, in particular wood, is digested with acetic acid, for example by the process described in DE-A-3 445 132. In particular when using coniferous wood (eg spruce wood), this offers considerable advantages because the peroxide consumption is then comparatively high in the known treatment with peroxides.
Allgemein scheint ein gewisser Zusammenhang zwischen dem Ligningehalt (ausgedrückt als Kappazahl) einer Cellulosemasse und dem optimalen Einsatz der erfindungsgemässen Behandlung mit Ozon zu bestehen; optimale Ergebnisse werden häufig dann erhalten, wenn durch das Aufschlussverfahren (vorzugsweise ebenfalls in C₁₋₃-Fettsäure, insbesondere Essigsäure) der Kappawert auf etwa 20 (entspricht einem Ligningehalt von ca. 3%) gebracht und dann durch die erfindungsgemässe Ozonbehandlung in Essigsäure soweit abgesenkt wird, z.B. auf Kappawerte von unter 5, dass durch eine vorzugsweise durchgeführte abschliessende Bleiche mit Peressigsäure ein gewünschter End-Weissgrad von typisch über 70% ISO erreicht werden kann.In general, there appears to be a certain connection between the lignin content (expressed as kappa number) of a cellulose mass and the optimal use of the treatment according to the invention with ozone; Optimal results are often obtained when the kappa value is brought to about 20 (corresponds to a lignin content of approx. 3%) by the digestion process (preferably also in C₁₋₃ fatty acid, especially acetic acid) and then reduced by the inventive ozone treatment in acetic acid will, e.g. to kappa values of less than 5, that a desired final whiteness of typically over 70% ISO can be achieved by a preferred final bleaching with peracetic acid.
Die hier angegebenen Kappawerte oder Kappazahlen wurden nach der Methode bestimmt, die im Merkblatt IV/37/80 des Fachausschusses für chemische Zellstoff- und Papierprüfung im Verein der Zellstoff- und Papierchemiker und -ingenieure (BR Deutschland) beschrieben ist.The kappa values or kappa numbers given here were determined using the method described in Leaflet IV / 37/80 of the Technical Committee for Chemical Pulp and Paper Testing in the Association of Pulp and Paper Chemists and Engineers (BR Germany).
Weissgrade im eben erwähnten Bereich sind auch erreichbar, wenn zuerst mit Peressigsäure und danach mit Ozon gebleicht wird. Nach dem Stand der Technik waren Weissgrade von über 70% ISO nach dem Essigsäureaufschluss nur mit verhältnismässig grossen Mengen an Peroxid zu erzielen. Weissgrade von über 80% ISO können erfindungsgemäss erreicht werden, wenn der Zellstoff in einer dreistufigen Bleiche zuerst mit Ozon (Z), danach mit H₂O₂ (P) und abschliessend nochmals mit Ozon (Z) oder mit einer PZP-Bleichfolge im gleichen Lösungsmittel, d.h. C₁₋₃-Fettsäure bzw. Essigsäure, behandelt wird.Whiteness levels in the range just mentioned can also be achieved if bleaching is carried out first with peracetic acid and then with ozone. According to the prior art, whitenesses of over 70% ISO after digestion of acetic acid could only be achieved with relatively large amounts of peroxide. According to the invention, degrees of whiteness of over 80% ISO can be achieved if the pulp is first bleached with ozone in a three-stage bleach (Z), then treated with H₂O₂ (P) and finally again with ozone (Z) or with a PZP bleaching sequence in the same solvent, ie C₁₋₃ fatty acid or acetic acid.
Das erfindungsgemässe Verfahren ist insbesondere als Verfahrensstufe in einem "Gegenstromverfahren" vorteilhaft, das z.B. mit bekannten Karussell-Extraktoren gemäss den Angaben in der Zeitschrift "Holz als Roh- und Werkstoff", 44 (1986) 207-212, durchgeführt werden kann; dabei wird gemäss einer bevorzugten Ausführungsform Essigsäure mit oder ohne Ozon nicht nur für die abschliessende Extraktion, sondern als einziges Ligninlösungsmittel verwendet. In diesem Falle ist eine Arbeitsweise bei niedriger Konsistenz, vorzugsweise 2 bis 10% Zellstoff, und Ozonkonzentrationen unter 2%, vorzugsweise 0,5 bis 1,5%, möglich. Auch hierbei soll die Essigsäure weniger als 50 Gew.% Wasser, vorzugsweise weniger als 30 Gew.% und insbesondere weniger als 10 Gew.% Wasser, enthalten. Statt Wasser kann jedoch auch ein Zusatz eines anderen Stoffes, insbesondere einer anderen C₁₋₃-Fettsäure, dienen, d.h. es kann auch mit Essigsäure gearbeitet werden, die z.B. 1 bis 50 Gew.% Propion- oder/und Ameisensäure enthält.The process according to the invention is particularly advantageous as a process stage in a "countercurrent process" which e.g. with known carousel extractors according to the information in the magazine "Wood as raw and material", 44 (1986) 207-212, can be carried out; According to a preferred embodiment, acetic acid with or without ozone is used not only for the final extraction, but as the only lignin solvent. In this case, operation with a low consistency, preferably 2 to 10% pulp, and ozone concentrations below 2%, preferably 0.5 to 1.5%, is possible. Here too, the acetic acid should contain less than 50% by weight of water, preferably less than 30% by weight and in particular less than 10% by weight of water. Instead of water, however, an addition of another substance, in particular another C₁₋₃ fatty acid, can also serve, i.e. it can also be used with acetic acid, e.g. Contains 1 to 50 wt.% Propionic and / or formic acid.
Allgemein sind zur Durchführung des erfindungsgemässen Verfahrens als gesonderte Behandlung oder als Schritt in einer Folge von Behandlungen bzw. Verarbeitungen bei der Zellstoffgewinnung an sich bekannte Vorrichtungen geeignet, die mindestens eine Kammer oder Zone zur Aufnahme der die Fett-bzw. Essigsäure enthaltenden Cellulosemasse aufweisen, wenn diese Vorrichtungen an sich bekannte Einrichtungen zur Behandlung mit einer Ozon enthaltenden Gasphase aufweisen. Die mit der Masse bzw. der Gasphase in Kontakt kommenden Teile der Vorrichtung bestehen aus entsprechend resistenten Werkstoffen, vorzugsweise Stahllegierungen.In general, devices known per se are suitable for carrying out the method according to the invention as a separate treatment or as a step in a sequence of treatments or processing operations in the production of cellulose, which devices have at least one chamber or zone for receiving the fat or. Cellulose mass containing acetic acid if these devices have devices known per se for treatment with a gas phase containing ozone. The parts of the device which come into contact with the mass or the gas phase consist of correspondingly resistant materials, preferably steel alloys.
Wie bereits eingangs angedeutet, werden die Eigenschaften, z.B. die Kennwerte des erhaltenen Zellstoffes, wie Reisslänge, Berstfläche und Durchreissfestigkeit, durch die Behandlung mit Ozon nach dem erfindungsgemässen Verfahren nicht signifikant verändert; das erfindungsgemässe Verfahren ermöglicht die Gewinnung von Zellstoffprodukten, deren Qualität derjenigen der konventionellen, nach dem Sulfatverfahren erhältlichen Zellstoffe entspricht und erheblich besser ist als diejenige der nach dem Sulfitverfahren erhaltenen Produkte.As already indicated at the beginning, the properties, e.g. the characteristic values of the pulp obtained, such as tear length, rupture area and tear resistance, were not significantly changed by the treatment with ozone by the process according to the invention; the process according to the invention enables pulp products to be obtained, the quality of which corresponds to that of the conventional pulps obtainable by the sulfate process and is considerably better than that of the products obtained by the sulfite process.
Die Erfindung wird anhand folgender Beispiele erläutert. Die Bezeichnung DPw bedeutet den auf das Gewichtsmittel-Molekulargewicht bezogenen, Polymerisationsgrad.The invention is illustrated by the following examples. The term DP w means the degree of polymerization, based on the weight average molecular weight.
(A) 289 g essigsäurefeuchte Cellulosemasse in Form von Zellstoff aus Fichtenholz, enthaltend ca. 8 Gew.% Lignin (50 g atro, Kappazahl 59), werden mit 2 Liter 93%iger Essigsäure in einem Becherglas mit einem starken Rührer 8 min aufgeschlagen, auf einer Fritte scharf abgesaugt und mit heisser 93%iger Essigsäure nachgewaschen. Danach hat der Zellstoff die Kappazahl 24. Er wird mit 600 ml 93%iger Essigsäure, die 7 g H₂O₂ enthält, 5 Std. im Rundkolben bei 70°C rotiert. Der so behandelte Zellstoff wird erneut auf einer Fritte scharf abgesaugt und mit heisser Essigsäure nachgewaschen.
(B) Es wird wie in Absatz A gearbeitet, jedoch mit der Abänderung, dass der mit 1,75 g H₂O₂ statt mit 7 g H₂O₂ gebleichte Zellstoff (270 g feucht, 48,5 g atro) in aufgeflufftem Zustand in einem rotierenden Rundkolben bei 20°C 1 Std. mit Ozon (10 Liter, 3,5% Ozon in Sauerstoff) begast wird. Danach wird er auf einer Fritte mit heisser Essigsäure gewaschen.
(A) 289 g of cellulose mass moistened with acetic acid in the form of pulp made of spruce wood, containing approx. 8% by weight of lignin (50 g dry, Kappa number 59), are beaten with 2 liters of 93% acetic acid in a beaker with a strong stirrer for 8 min. sucked off sharply on a frit and washed with hot 93% acetic acid. Then the pulp has the Kappa number 24. It is rotated with 600 ml of 93% acetic acid containing 7 g of H₂O₂ for 5 hours in a round bottom flask at 70 ° C. The pulp treated in this way is again sucked off sharply on a frit and washed with hot acetic acid.
(B) The procedure is as in paragraph A, but with the modification that the bleached pulp bleached with 1.75 g H₂O₂ instead of 7 g H₂O₂ (270 g moist, 48.5 g dry) in a rotating round bottom flask 20 ° C for 1 hour with ozone (10 liters, 3.5% ozone in oxygen). Then it is washed on a frit with hot acetic acid.
50 g Zellstoff, welcher aus Kiefernhackschnitzeln (Pinus sylvestris, 45 Jahre) nach dem Acetosolv-Verfahren hergestellt wurde (Kappazahl 24,2), werden bis auf einen Feuchtigkeitsgehalt von 35% abgepresst und anschliessend mechanisch zerkleinert. Der zerfaserte Stoff wird in einen Kolben gegeben und mit 1 bis 3,3% Ozon behandelt (0,05 g Ozon/min, 0,06 g Ozon/Liter Sauerstoff). Nach einer Einwirkungsdauer von 10 bis 40 min wird der Zellstoff mit Essigsäure und anschliessend mit Wasser gewaschen.
267,4 g atro Kiefernholz (Pinus sylvestris, 45 Jahre) werden nach dem Acetosolv-Verfahren aufgeschlossen. Der Zellstoff wird wie in Beispiel 2 mit 2% Ozon gebleicht (erste Bleichstufe) und mit Essigsäure gewaschen. Bei einer Konsistenz von 12% Zellstoff in Essigsäure wird 1% Wasserstoffperoxid zugesetzt und während 6 Std. bei 70°C gebleicht (zweite Bleichstufe). Der erhaltene Zellstoff wird mit Essigsäure gewaschen, auf 35% Feststoffgehalt abgepresst und erneut mit 0,6% Ozon behandelt (dritte Bleichstufe).
Anstelle der in den Beispielen 1-3 verwendeten Essigsäure können in der Regel auch C₁₋₃-Fettsäuremischungen verwendet werden, die z.B. bei der Hydrolyse von Pflanzenabfällen erhältlich sind und aus Mischungen von Essigsäure, Propionsäure und Ameisensäure bestehen.Instead of the acetic acid used in Examples 1-3, C₁₋₃ fatty acid mixtures which, for example, are available in the hydrolysis of plant waste and consist of mixtures of acetic acid, propionic acid and formic acid.
Claims (8)
- A method of treating a lignin-containing cellulosic mass with ozone in the presence of C₁₋₃ fatty acid characterized in that said cellulosic material, in mixture with at least one C₁₋₃ fatty acid containing less than 50% by weight of water, is subjected to the action of a gaseous phase containing ozone in an amount of from 0.1 to 10 % by volume so as to increase solubility of said lignin in said C₁₋₃ fatty acid by an oxidative alteration of said lignin, and that said lignin so altered is separated together with said C₁₋₃ fatty acid from said cellulosic mass.
- The method of claim 1 characterized in that acetic acid is used as said C₁₋₃ fatty acid.
- The method of claim 1 or 2 characterized in that said treatment of said cellulosic mass with ozone is effected at temperatures of below 100°C, preferably below 50°C and notably between 0 and 30°C.
- The method according to any of claims 1 to 3 characterized in that it is applied as a delignification step with a C₁₋₃ fatty acid in the production of bleached pulp wherein said C₁₋₃ fatty acid is a component of the process liquor in a preceding step and serves, at least in part, as liquid processing medium in a bleaching treatment with peroxide.
- The method of claim 4 characterized in that said ozone treatment in said C₁₋₃ fatty acid, notably acetic acid, is carried out before and/or after a treatment with peracetic acid.
- The method according to claim 4 or 5 characterized in that it is carried out as a step in a counter-current process.
- The method according to any of claims 4 to characterized in that the pulp concentration is between 1 and 50%, preferably 25 to 40%, and the ozone concentration in said C₁₋₃ fatty acid is below 3%, preferably between 0.1 and 1.5%, based upon the dry weight of said pulp.
- The method of any of claims 1 to 7 characterized in that said water content of said fatty acid or said mixture of fatty acids is from 1 to 10% by weight.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP88810034A EP0325890B1 (en) | 1988-01-25 | 1988-01-25 | Process for treating lignin containing cellulose pulp with ozone |
| AT88810034T ATE90404T1 (en) | 1988-01-25 | 1988-01-25 | PROCESS FOR TREATMENT OF LIGNIN-CONTAINING CELLULOSE MASS WITH OZONE. |
| ES198888810034T ES2041828T3 (en) | 1988-01-25 | 1988-01-25 | PROCEDURE FOR THE TREATMENT OF CELLULOSE MASS CONTAINING LIGNIN, WITH OZONE. |
| DE8888810034T DE3881676D1 (en) | 1988-01-25 | 1988-01-25 | METHOD FOR TREATING LIGNINE-CONTAINING CELLULOSE MASS WITH OZONE. |
| CA000588913A CA1319472C (en) | 1988-01-25 | 1989-01-23 | Lignin removal method |
| BR898900299A BR8900299A (en) | 1988-01-25 | 1989-01-25 | PROCESS FOR THE SEPARATION OF CELLULOSE MASS LIGNIN, DEVICE FOR CARRYING OUT THE PROCESS AND CELLULOSE MASS PREPARED BY THE PROCESS |
| JP1017414A JPH01221587A (en) | 1988-01-25 | 1989-01-25 | Removal of lignin from pulp |
| US07/606,595 US5074960A (en) | 1988-01-25 | 1990-10-31 | Lignin removal method using ozone and acetic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP88810034A EP0325890B1 (en) | 1988-01-25 | 1988-01-25 | Process for treating lignin containing cellulose pulp with ozone |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0325890A1 EP0325890A1 (en) | 1989-08-02 |
| EP0325890B1 true EP0325890B1 (en) | 1993-06-09 |
Family
ID=8200568
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP88810034A Expired - Lifetime EP0325890B1 (en) | 1988-01-25 | 1988-01-25 | Process for treating lignin containing cellulose pulp with ozone |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5074960A (en) |
| EP (1) | EP0325890B1 (en) |
| JP (1) | JPH01221587A (en) |
| AT (1) | ATE90404T1 (en) |
| BR (1) | BR8900299A (en) |
| CA (1) | CA1319472C (en) |
| DE (1) | DE3881676D1 (en) |
| ES (1) | ES2041828T3 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2053035C (en) * | 1990-10-12 | 1997-09-30 | Repap Enterprises Inc. | Chlorine-free wood pulps and process of making |
| DE4107354C1 (en) * | 1991-03-08 | 1992-11-05 | Acetocell Gmbh & Co Kg, 7162 Gschwend, De | |
| DE4107357C1 (en) * | 1991-03-08 | 1992-11-05 | Acetocell Gmbh & Co Kg, 7162 Gschwend, De | |
| SE470234B (en) * | 1992-05-13 | 1993-12-13 | Kamyr Ab | Method of bleaching cellulosic fibrous material with ozone in the presence of an organic compound |
| JP3121917B2 (en) * | 1992-07-08 | 2001-01-09 | 住友重機械工業株式会社 | Pulp bleaching method with ozone |
| DE4228171C2 (en) * | 1992-08-25 | 1995-06-14 | Kaemmerer Projekt Agentur Gmbh | Process for the production of cellulose |
| US5387317A (en) * | 1993-01-28 | 1995-02-07 | The Mead Corporation | Oxygen/ozone/peracetic aicd delignification and bleaching of cellulosic pulps |
| US5411635A (en) * | 1993-03-22 | 1995-05-02 | The Research Foundation Of State University Of New York | Ozone/peroxymonosulfate process for delignifying a lignocellulosic material |
| JP3312138B2 (en) * | 1998-12-02 | 2002-08-05 | 独立行政法人 森林総合研究所 | Wood board and its manufacturing method |
| US6468953B1 (en) | 2000-08-03 | 2002-10-22 | Lynntech, Inc. | Methods of preparing antimicrobial compositions comprising ozone |
| AU2002225936A1 (en) * | 2000-11-03 | 2002-05-15 | Penwest Pharmaceutical Company | Process for producing microcrystalline cellulose with a desired dp |
| US20020107288A1 (en) * | 2000-12-08 | 2002-08-08 | Singh Waheguru Pal | Methods of sterilizing with dipercarboxylic acids |
| WO2005064076A1 (en) * | 2003-12-25 | 2005-07-14 | Xiuquan Mei | Closed cycle zero discharge oxidizing pulping process |
| US7824521B2 (en) * | 2006-12-18 | 2010-11-02 | University Of Maine System Board Of Trustees | Process of treating a lignocellulosic material with hemicellulose pre-extraction and hemicellulose adsorption |
| US20100159522A1 (en) * | 2008-12-19 | 2010-06-24 | E.I. De Pont De Nemours And Company | Organosolv and ozone treatment of biomass to enhance enzymatic saccharification |
| WO2010080489A1 (en) * | 2008-12-19 | 2010-07-15 | E. I. Du Pont De Nemours And Company | Ozone treatment of biomass to enhance enzymatic saccharification |
| US8216809B2 (en) * | 2008-12-19 | 2012-07-10 | E I Du Pont De Nemours And Company | Organic solvent pretreatment of biomass to enhance enzymatic saccharification |
| EP2513150A1 (en) * | 2009-12-18 | 2012-10-24 | Shell Internationale Research Maatschappij B.V. | A process for the extraction of sugars and lignin from lignocellulose-comprising solid biomass |
| US9382282B2 (en) * | 2011-09-09 | 2016-07-05 | University Of Tennessee Research Foundation | Metal catalyzed oxidation of lignin and related compounds |
| ES2386045B1 (en) * | 2012-05-03 | 2013-04-18 | Saica Pack, S.L. | PROCEDURE FOR OBTAINING NANOFIBRILLED CELLULOSE FROM RECOVERED PAPER |
| ES2384931B1 (en) * | 2012-05-03 | 2013-03-20 | Saica Pack, S.L. | Procedure for obtaining nanodispersed cellulose from recovered paper |
| FR3016359B1 (en) * | 2014-01-10 | 2022-04-29 | Arkema France | HYDROGEN PEROXIDE COMPOSITIONS FOR THE DELIGNIFICATION OF PLANT MATERIAL AND THEIR USES |
| WO2018013796A1 (en) * | 2016-07-14 | 2018-01-18 | University Of Kansas | Continuous process for the ozonolysis of lignin to yield aromatic monomers |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3553076A (en) * | 1968-01-22 | 1971-01-05 | Weyerhaeuser Co | Non-catalytic process for the production of cellulose from lignocellulosic materials using acetic acid |
| US4119486A (en) * | 1975-08-14 | 1978-10-10 | Westvaco Corporation | Process for bleaching wood pulp with ozone in the presence of a cationic surfactant |
| CA1090510A (en) * | 1976-06-02 | 1980-12-02 | Arthur W. Kempf | Delignification and bleaching of a lignocellulosic pulp slurry with ozone |
| US4372812A (en) * | 1978-04-07 | 1983-02-08 | International Paper Company | Chlorine free process for bleaching lignocellulosic pulp |
| US4278477A (en) * | 1980-03-19 | 1981-07-14 | Amchem Products, Inc. | Metal treatment |
| DE3445132A1 (en) * | 1984-12-11 | 1986-06-12 | Nimz, Horst H., Prof.Dr., 2050 Hamburg | Wood pulping with acetic acid |
-
1988
- 1988-01-25 ES ES198888810034T patent/ES2041828T3/en not_active Expired - Lifetime
- 1988-01-25 EP EP88810034A patent/EP0325890B1/en not_active Expired - Lifetime
- 1988-01-25 DE DE8888810034T patent/DE3881676D1/en not_active Expired - Fee Related
- 1988-01-25 AT AT88810034T patent/ATE90404T1/en not_active IP Right Cessation
-
1989
- 1989-01-23 CA CA000588913A patent/CA1319472C/en not_active Expired - Fee Related
- 1989-01-25 JP JP1017414A patent/JPH01221587A/en active Pending
- 1989-01-25 BR BR898900299A patent/BR8900299A/en not_active Application Discontinuation
-
1990
- 1990-10-31 US US07/606,595 patent/US5074960A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE3881676D1 (en) | 1993-07-15 |
| BR8900299A (en) | 1989-09-19 |
| ES2041828T3 (en) | 1993-12-01 |
| EP0325890A1 (en) | 1989-08-02 |
| JPH01221587A (en) | 1989-09-05 |
| ATE90404T1 (en) | 1993-06-15 |
| US5074960A (en) | 1991-12-24 |
| CA1319472C (en) | 1993-06-29 |
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