EP1585772A1 - Method for the production of a porous cellulose body - Google Patents
Method for the production of a porous cellulose bodyInfo
- Publication number
- EP1585772A1 EP1585772A1 EP04703120A EP04703120A EP1585772A1 EP 1585772 A1 EP1585772 A1 EP 1585772A1 EP 04703120 A EP04703120 A EP 04703120A EP 04703120 A EP04703120 A EP 04703120A EP 1585772 A1 EP1585772 A1 EP 1585772A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cellulose
- aqueous medium
- porous
- cellulosic
- supercritical solvent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 229920002678 cellulose Polymers 0.000 title claims abstract description 71
- 239000001913 cellulose Substances 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 239000012736 aqueous medium Substances 0.000 claims abstract description 33
- 239000002904 solvent Substances 0.000 claims abstract description 27
- 239000007788 liquid Substances 0.000 claims abstract description 10
- 239000002609 medium Substances 0.000 claims abstract description 10
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 11
- 150000003512 tertiary amines Chemical class 0.000 claims description 11
- 239000001569 carbon dioxide Substances 0.000 claims description 8
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 238000000197 pyrolysis Methods 0.000 claims description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims description 4
- 238000001556 precipitation Methods 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 claims description 2
- 125000004432 carbon atom Chemical group C* 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 claims description 2
- 238000004140 cleaning Methods 0.000 claims description 2
- 239000003431 cross linking reagent Substances 0.000 claims description 2
- 239000007772 electrode material Substances 0.000 claims description 2
- 239000000835 fiber Substances 0.000 claims description 2
- 239000000446 fuel Substances 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims description 2
- 239000012774 insulation material Substances 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- 238000003860 storage Methods 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 10
- 230000001376 precipitating effect Effects 0.000 abstract description 4
- 125000001302 tertiary amino group Chemical group 0.000 abstract 4
- 239000003795 chemical substances by application Substances 0.000 abstract 3
- LFTLOKWAGJYHHR-UHFFFAOYSA-N N-methylmorpholine N-oxide Chemical compound CN1(=O)CCOCC1 LFTLOKWAGJYHHR-UHFFFAOYSA-N 0.000 abstract 1
- 238000001035 drying Methods 0.000 description 13
- 239000011324 bead Substances 0.000 description 11
- 239000004964 aerogel Substances 0.000 description 10
- 239000011148 porous material Substances 0.000 description 9
- 239000000499 gel Substances 0.000 description 7
- 239000003960 organic solvent Substances 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 229920000297 Rayon Polymers 0.000 description 5
- 238000000352 supercritical drying Methods 0.000 description 5
- 150000001412 amines Chemical class 0.000 description 3
- 239000002270 dispersing agent Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011049 pearl Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229920002301 cellulose acetate Polymers 0.000 description 2
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- ZOOODBUHSVUZEM-UHFFFAOYSA-N ethoxymethanedithioic acid Chemical compound CCOC(S)=S ZOOODBUHSVUZEM-UHFFFAOYSA-N 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000012991 xanthate Substances 0.000 description 2
- 239000004966 Carbon aerogel Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 239000011240 wet gel Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
- C08J2201/054—Precipitating the polymer by adding a non-solvent or a different solvent
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/08—Supercritical fluid
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Definitions
- the present invention relates to a method for producing a porous cellulosic body, a porous cellulosic body and its use and a porous carbon body which can be produced from the cellulosic body by pyrolysis and its use.
- porous bodies according to the invention are so-called aerogels.
- aerogels are highly porous solids with very low density.
- aerogels are materials in which the pore and network structure is completely or largely preserved when the pore fluid of a gel is replaced by air.
- a gel consists of a sponge-like, three-dimensional network, the pores of which are filled with a liquid.
- aerogels in which the network structure remains essentially unchanged during drying, conventionally drying (increasing the temperature and / or reducing the pressure) gives strongly shrunk bodies, which are called xerogels.
- the shrinkage of the gel is caused by the capillary forces at the liquid / gaseous interface of the evaporating pore liquid.
- aerogels The unique optical, thermal, acoustic and mechanical properties of aerogels are caused by the combination of a solid matrix with air-filled pores in the nanometer range.
- the majority of industrially produced aerogels are inorganic in nature and consist of silica and metal oxides.
- organic aerogels are also known (for example US Department of Energy, US 4,873,218).
- a cellulose xanthate solution or cellulose acetate, which is hydrolyzed, is generally assumed.
- Viscose solution of cellulose xanthate in dilute sodium hydroxide solution
- a water-immiscible organic solvent such as chlorobenzene
- the cellulosic bodies obtained in this way have porosities (volume fraction water) of 90%.
- the water can (according to: J. Stamberg et al., Acta Polymerica 30 (1979) Issue 12, 734-739) be replaced by various organic solvents, and the degree of porosity remains almost unchanged.
- the highest porosity value of a dried cellulose body known to the applicant is a value of 83.6%, which is described in Peska et al., Cell. Chem. Techn. 21 (1978) pp. 419-428.
- DD 1 18,887 corresponds to US 4,055,510
- WO 91/09878 corresponds to US 5,527,902
- DD 118,887 contains the statement that only cellulose balls with a low pore volume of less than 30% are dimensionally stable and can be dried without special measures to maintain the porosity.
- a hydrolyzable cellulose derivative such as e.g. Cellulose acetate dissolved in a water-miscible organic solvent, the solution divided into drops and introduced into a precipitation bath (e.g. water), the beads separated, washed, the cellulose derivative hydrolyzed to cellulose and washed again.
- a precipitation bath e.g. water
- the drying with supercritical carbon dioxide mentioned in Example 1 is used exclusively for the preparation of a pattern suitable for characterization by means of electron microscopy.
- a disadvantage of many processes known from the prior art are ecological problems, such as the use of chlorinated organic solvents, the emission of toxic sulfur compounds in the viscose process or the use of copper-containing solvents for the cellulose.
- WO 99/31 141 contains the description of a process with the following steps:
- the solution becomes a jet with a diameter in the range from 40 ⁇ m to
- N-Methylmo ⁇ holin-N-oxide is used as a solvent for cellulose in the examples.
- example 2 beads with an average diameter of 2.2 mm are obtained. After pyrolysis of the beads, which also contain a proportion of Al 2 O, and subsequent sintering, the beads have a diameter of 1.1 mm. In another example (example 4), the undried beads have an average diameter of 3.13 mm. After drying (not described in detail), the diameter is only 0.8 mm. It can therefore be assumed that the porosity of these pearls has drastically reduced during drying.
- the method according to the invention for the production of porous cellulosic bodies comprises the steps Production of a cellulose solution in a tertiary amine oxide, in particular N-methylmo ⁇ holin-N-oxide, the cellulose used having an average degree of polymerization of 150 to 2000 and the solution having a cellulose concentration of 0.1 to 5% by weight, production of a body the cellulose solution
- Precipitation of the body in a precipitant whereby a precipitated cellulosic body is obtained, the precipitant being an aqueous medium or a cellulose-precipitating, water-miscible, non-aqueous medium which is non-aqueous
- Solvent is miscible and is characterized in that if an aqueous medium is used as the precipitant in the precipitated cellulosic body, tertiary amine oxide contained in the precipitated cellulose is washed out with the aqueous medium, the aqueous medium is exchanged for a liquid exchange medium which is miscible with a supercritical solvent and which is moist with the exchange medium cellulosic body is treated with the supercritical solvent, whereby the porous cellulosic body is obtained or that, if a non-aqueous medium is used as a precipitant, tertiary amine oxide contained in the precipitated cellulosic body is washed out with the non-aqueous medium which is washed with the non-aqueous medium. aqueous medium moist cellulosic body is treated with the supercritical solvent, whereby the porous cellulosic body is obtained.
- cellulosic means cellulose, cellulose derivatives soluble in tertiary amine oxides and mixtures of cellulose and / or soluble cellulose derivatives and other polymers soluble in NMMO, such as, for example, polyamides.
- NMMO N-methylmo ⁇ holin-N-oxide
- Carbon dioxide is preferably used as the supercritical solvent in the process according to the invention.
- Organic solvents which are suitable as precipitants for the purposes of the present invention are water-miscible, act as precipitants in relation to cellulose in amine oxide solutions, are able to dissolve NMMO, should cause the primary gel swelling of the cellulose to be as high as possible and should be good with supercritical carbon dioxide be miscible.
- Acetone can also be used as the non-aqueous medium or as the liquid exchange medium.
- the aqueous medium which can be used as a precipitant, can consist of water or of mixtures of water with other solvents (provided the cellulose-precipitating effect is retained).
- the precipitant (aqueous medium or non-aqueous medium) can additionally contain further components, such as e.g. Parts of solvent (amine oxide) included.
- an alcohol or acetone-moist gel is covered in an autoclave with excess alcohol / acetone (to prevent premature drying), then the temperature and the CO 2 pressure are slowly increased and for some time at values above the critical point of C0 2 (31, 1 ° C / 73.8 bar) held until the solvent in the cellulose body is removed quantitatively. The pressure and temperature are then adjusted so that the CO 2 is slowly removed in the gaseous state.
- the cellulose solution is processed in a manner known per se, e.g. by extrusion through a molding tool or by casting into a corresponding mold, formed into a shaped body.
- the molded body can be, for example, a fiber, a film, a block or a plate.
- spherical or pearl-shaped particles can also be produced from the cellulose solution by dropping the solution or, for example, using the technology described in WO 99/31 141.
- particles can be produced from the solution by means of the jet cutter technology (from Genialab) and by means of vibration nozzles.
- a powder can also be produced from a large number of porous cellulose particles.
- a further preferred embodiment of the method according to the invention is characterized in that the cellulosic body is treated with a crosslinking agent, such as e.g. described in WO 91/09878.
- porous cellulosic body produced by the process according to the invention can also be subjected to pyrolysis.
- the method according to the invention it is possible for the first time to provide a porous cellulosic body with a porosity in the dry state of 85% and more.
- the body obtained by treatment with the supercritical solvent is thus a highly porous airgel.
- the cellulosic body according to the invention preferably has a porosity of 90% and more, particularly preferably of 95% and more.
- the porosity is defined as follows for the purposes of the present invention: The cellulosic body obtained is measured in a microscope and the volume is calculated therefrom. The cellulosic body is weighed, which gives the density of the body (mass / volume).
- the formula (1 - density of the body / 1, 6) * 100 gives the porosity of the body, ie the percentage of voids in the body. In the case of a large number of bodies (eg pearls), the average is taken from several measurements.
- the invention further relates to a porous cellulosic body which can be obtained by the process according to the invention.
- This body differs from known porous cellulosic bodies produced by the amine oxide process, e.g. described in WO 99/31 141 and WO 02/057319, characterized in that the porosity is significantly higher in the dry state.
- cellulosic bodies according to the invention can be used in particular as insulation material, for example in thermal or acoustic insulation. Furthermore, the cellulosic bodies according to the invention can be used as a dielectric in the electrical and electronics industry, for impedance matching in acoustic applications, as a means for absorbing and cleaning gases, as a carrier for catalysts and / or as a means for storing energy sources, such as e.g. Hydrogen.
- the invention further relates to a porous carbon body which can be obtained from the cellulosic body according to the invention by means of pyrolysis.
- the carbon airgel resulting after pyrolysis of the cellulose component is suitable as an electrode material for batteries, accumulators, capacitors and fuel cells and for high-temperature insulation.
- Such carbon aerogels in analogy to carbon nanotubes, represent efficient hydrogen stores.
- a cellulose solution with 1% by weight> cellulose (cellulose Solucell with a viscosity according to SCAN CM 15:88 500) / 82% by weight NMMO / 17% by weight H 2 O was prepared in a manner known per se. This solution was dropped in water as a precipitant Washed out solvent with water and then exchanged the water for ethanol.
- the ethanol-moist bodies (spheres with a diameter of approximately 3 mm) were placed in an autoclave, covered with additional ethanol, heated to 50 ° C. and 130 bar of CO 2 were added for 2.5 hours.
- the CO 2 was kept in circulation, which was reduced in the cycle of pressure in two stages, each with a liquid at 60 and 40 bar, then the C0 2 has been re-compressed to 130 bar. After the two and a half hours mentioned, the CO 2 was then discharged at 50.degree.
- Cellulose balls with the same diameter (approx. 3 mm) as the moist starting product were obtained.
- the density of the cellulose balls was 0.042 g / cm 3 ; according to the above calculation formula, this means that the pore volume is 97.4%.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
Description
Verfahren zur Herstellung eines porösen cellulosischen KörpersProcess for the production of a porous cellulosic body
Die vorliegende Erfindung betrifft ein Verfahren zur Herstellung eines porösen cellulosischen Körpers, einen porösen cellulosischen Köφer und dessen Verwendung sowie einen durch Pyrolyse aus dem cellulosischen Köφer herstellbaren porösen Kohlenstoffköφer und dessen Verwendung.The present invention relates to a method for producing a porous cellulosic body, a porous cellulosic body and its use and a porous carbon body which can be produced from the cellulosic body by pyrolysis and its use.
Die erfindungsgemäßen porösen Köφer sind sogenannte Aerogele.The porous bodies according to the invention are so-called aerogels.
Nach Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2002 Electronic Release sind Aerogele hoch poröse Festköφer mit sehr niedriger Dichte. In einer engeren Definition sind Aerogele Materialien, in denen die Poren- und Netzwerkstruktur völlig oder weitgehend erhalten bleibt, wenn die Porenflüssigkeit eines Gels durch Luft ersetzt wird.According to Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2002 Electronic Release, aerogels are highly porous solids with very low density. In a narrower definition, aerogels are materials in which the pore and network structure is completely or largely preserved when the pore fluid of a gel is replaced by air.
Ein Gel besteht aus einem schwammartigen, dreidimensionalen Netzwerk, dessen Poren mit einer Flüssigkeit gefüllt sind. Im Gegensatz zu Aerogelen, bei denen beim Trocknen die Netzwerkstruktur im wesentlichen unverändert bleibt, werden durch konventionelle Trocknung (Erhöhung der Temperatur und/oder Verringerung des Drucks) stark geschrumpfte Köφer erhalten, die Xerogele genannt werden. Die Schrumpfung des Gels wird verursacht durch die Kapillarkräfte an der Grenzfläche flüssig/gasförmig der verdampfenden Porenflüssigkeit.A gel consists of a sponge-like, three-dimensional network, the pores of which are filled with a liquid. In contrast to aerogels, in which the network structure remains essentially unchanged during drying, conventionally drying (increasing the temperature and / or reducing the pressure) gives strongly shrunk bodies, which are called xerogels. The shrinkage of the gel is caused by the capillary forces at the liquid / gaseous interface of the evaporating pore liquid.
Die Art der Trocknung des Gels ist somit der entscheidende Schritt für die Herstellung hoch poröser Aerogele. Angewandt werden die Technologien:The type of drying of the gel is therefore the decisive step for the production of highly porous aerogels. The technologies are applied:
- überkritische Trocknung- supercritical drying
- in organischen Lösungsmitteln- in organic solvents
- in Kohlendioxid (im folgenden wird der Begriff „überkritisches Lösungsmittel" sowohl für überkritische organische Lösungsmittel als auch für überkritisches Kohlendioxid verwendet)- in carbon dioxide (hereinafter the term "supercritical solvent" is used both for supercritical organic solvents and for supercritical carbon dioxide)
- Gefriertrocknung- Freeze drying
- Trocknung bei Normaldruck - dies ist aber nur bei besonders stabilen Netzwerken möglich.- Drying at normal pressure - this is only possible with particularly stable networks.
Die einzigartigen optischen, thermischen, akustischen und mechanischen Eigenschaften von Aerogelen werden durch die Kombination einer festen Matrix mit luftgefüllten Poren im Nanometerbereich hervorgerufen. Die Hauptmenge industriell hergestellter Aerogele ist anorganischer Natur und besteht aus Kieselsäure und Metalloxiden. Es sind jedoch auch organische Aerogele bekannt (z.B. U.S. Department of Energy, US 4 873 218).The unique optical, thermal, acoustic and mechanical properties of aerogels are caused by the combination of a solid matrix with air-filled pores in the nanometer range. The majority of industrially produced aerogels are inorganic in nature and consist of silica and metal oxides. However, organic aerogels are also known (for example US Department of Energy, US 4,873,218).
Für Cellulose sind hochporöse Formköφer bekannt, die Patentliteratur beschreibt jedoch mit wenigen Ausnahmen nur die Herstellung im nassen Zustand, in diesen Fällen handelt es sich somit nicht um Aerogele.Highly porous moldings are known for cellulose, but with few exceptions the patent literature only describes the production in the wet state, in these cases it is not aerogels.
Es wird im allgemeinen von einer Cellulosexanthogenatlösung oder von Celluloseacetat, welches hydrolysiert wird, ausgegangen.A cellulose xanthate solution or cellulose acetate, which is hydrolyzed, is generally assumed.
Bei der Herstellung nach dem Viskoseverfahren nach US 4,055,510 wirdIn the manufacture according to the viscose process according to US 4,055,510
- Viskose (Lösung von Cellulosexanthogenat in verdünnter Natronlauge) in einem mit Wasser nicht mischbaren organischen Lösungsmittel, wie Chlorbenzol, dispergiert,Viscose (solution of cellulose xanthate in dilute sodium hydroxide solution) dispersed in a water-immiscible organic solvent, such as chlorobenzene,
- die dispergierte Viskose mittels eines thermisch induzierten Sol-Gel-Überganges verfestigt (Erwärmen der Mischung auf 90°C),solidified the dispersed viscose by means of a thermally induced sol-gel transition (heating the mixture to 90 ° C.),
- es werden Celluloseperlen abgetrennt,- cellulose beads are separated,
- mit Säure im wäßrigen Medium regeneriert und- Regenerated with acid in an aqueous medium and
- gewaschen.- washed.
Die so erhaltenen cellulosischen Köφer weisen Porositäten (Volumsanteil Wasser) von 90% auf. Das Wasser kann (nach: J. Stamberg et al., Acta Polymerica 30 (1979) Heft 12, 734- 739) durch verschiedenste organische Lösungsmittel ersetzt werden, und der Porositätsgrad bleibt dabei fast unverändert.The cellulosic bodies obtained in this way have porosities (volume fraction water) of 90%. The water can (according to: J. Stamberg et al., Acta Polymerica 30 (1979) Issue 12, 734-739) be replaced by various organic solvents, and the degree of porosity remains almost unchanged.
Nach der Trocknung werden Produkte mit Porositätswerten von 0% bis 70% erhalten, je nachdem, welches Lösungsmittel vor der Trocknung mit Cellulose zuletzt in Kontakt war. Es ist jedoch daraus zu entnehmen, daß selbst unter den schonendsten Trocknungsbedingungen ein erheblicher Verlust an Porosität eintritt.After drying, products with porosity values of 0% to 70% are obtained, depending on which solvent was last in contact with cellulose before drying. However, it can be seen from this that even under the gentlest drying conditions there is a considerable loss of porosity.
Als höchster der Anmelderin bekannter Porositätswert eines getrockneten CellulosekÖφers ist ein Wert von 83,6 % anzusehen, der in Peska et al., Cell. Chem. Techn. 21 (1978) S. 419- 428 mitgeteilt wurde.The highest porosity value of a dried cellulose body known to the applicant is a value of 83.6%, which is described in Peska et al., Cell. Chem. Techn. 21 (1978) pp. 419-428.
Weitere Beispiele zur Herstellung von cellulosischen Köφern sind beschrieben in: Stamberg, J. „Bead Cellulose", Separation and Purification Methods 17(2) (1988)Further examples for the production of cellulosic bodies are described in: Stamberg, J. "Bead Cellulose", Separation and Purification Methods 17 (2) (1988)
155-183155-183
US 2,543,928US 2,543,928
DE 1 ,792,230 entspricht US 3,597,350DE 1, 792,230 corresponds to US 3,597,350
DD 1 18,887 entspricht US 4,055,510DD 1 18,887 corresponds to US 4,055,510
GB 1 ,575,700GB 1, 575,700
US 4,312,980US 4,312,980
US 4,946,953US 4,946,953
WO 91/00142WO 91/00142
WO 91/09878 entspricht US 5,527,902WO 91/09878 corresponds to US 5,527,902
US 5,328,603US 5,328,603
EP 850,979EP 850,979
Die DD 118,887 enthält die Aussage, daß nur Cellulosekugeln mit dem niedrigen Porenvolumen von unter 30% formstabil sind und ohne spezielle Maßnahmen zur Beibehaltung der Porosität getrocknet werden können.DD 118,887 contains the statement that only cellulose balls with a low pore volume of less than 30% are dimensionally stable and can be dried without special measures to maintain the porosity.
In der GB 1 ,575,700 wird ein hydrolysierbares Cellulosederivat wie z.B. Celluloseacetat in einem wassermischbaren organischen Lösungsmittel gelöst, die Lösung zu Tropfen zerteilt und in ein Fällbad (z.B. Wasser) eingetragen, die Perlen abgetrennt, gewaschen, das Cellulosederivat zu Cellulose hydrolysiert und noch einmal gewaschen. Es wird somit ein nasses Produkt beansprucht, die in Beispiel 1 erwähnte Trocknung mit überkritischem Kohlendioxid dient ausschließlich zur Präparation eines für die Charakterisierung mittels Elektronenmikroskopie geeigneten Musters.In GB 1, 575,700 a hydrolyzable cellulose derivative such as e.g. Cellulose acetate dissolved in a water-miscible organic solvent, the solution divided into drops and introduced into a precipitation bath (e.g. water), the beads separated, washed, the cellulose derivative hydrolyzed to cellulose and washed again. A wet product is thus claimed; the drying with supercritical carbon dioxide mentioned in Example 1 is used exclusively for the preparation of a pattern suitable for characterization by means of electron microscopy.
Nachteilig an vielen aus dem Stand der Technik bekannten Verfahren sind ökologische Probleme, wie der Einsatz von chlorierten organischen Lösungsmitteln, die Emission von toxischen Schwefelverbindungen beim Viskoseverfahren oder die Verwendung kupferhaltiger Lösungsmittel für die Cellulose. Verfahren, die alternative Celluloselösungsmittel, wie die Kombination Dimethylacetamid/Lithiumchlorid, einsetzen, sind bisher den Beweis einer industriell realisierbaren Rückgewinnungsmöglichkeit des Lösungsmittels schuldig geblieben.A disadvantage of many processes known from the prior art are ecological problems, such as the use of chlorinated organic solvents, the emission of toxic sulfur compounds in the viscose process or the use of copper-containing solvents for the cellulose. Processes that use alternative cellulose solvents, such as the combination of dimethylacetamide / lithium chloride, have so far failed to provide evidence of an industrially feasible recovery option for the solvent.
Verfahren ausgehend von Viskose oder auch Natriumhydroxid sind eingeschränkt auf das Lösen von Cellulose niedrigen Polymerisationsgrades. Die WO 99/31 141 enthält neben einer Übersicht über bisher eingesetzte Prozesse zur Herstellung von Celluloseperlen die Beschreibung eines Verfahrens mit den folgenden Schritten:Processes based on viscose or sodium hydroxide are restricted to the dissolution of cellulose with a low degree of polymerization. In addition to an overview of processes previously used for the production of cellulose beads, WO 99/31 141 contains the description of a process with the following steps:
- Herstellung einer Celluloselosung (Polymerisationsgrad 150 bis 2000, Cellulosekonzentration 0,5 bis Gew. 25%)- Preparation of a cellulose solution (degree of polymerization 150 to 2000, cellulose concentration 0.5 to 25% by weight)
- Feinzerteilen der Celluloselosung und Dispersion mit einem nicht mit der Lösung mischbaren Dispersionsmittel- Fine division of the cellulose solution and dispersion with a dispersant that is not miscible with the solution
- Verfestigung der Lösungsteilchen durch a) Abkühlen der Dispersion unter die Schmelztemperatur der Celluloselosung und Abtrennung der erstarrten Teilchen vom Dispersionmittel oder b) mittels Ausfällen der Teilchen mit einem mit dem Dispersionsmittel mischbaren Fällungsmittel- Solidification of the solution particles by a) cooling the dispersion below the melting temperature of the cellulose solution and separating the solidified particles from the dispersant or b) by precipitating the particles with a precipitant which is miscible with the dispersant
- Abtrennen der Perlteilchen von der Flüssigkeit.- separation of the pearl particles from the liquid.
Zur Herstellung von Teilchen mit einem Teilchengrößenbereich von 50 μm bis 1000 μm wird die Lösung zu einem Strahl mit einem Durchmesser im Bereich von 40 μm bisTo produce particles with a particle size range from 50 μm to 1000 μm, the solution becomes a jet with a diameter in the range from 40 μm to
1000 μm verformt und der Strahl mit Hilfe rotierender Schneidstrahlen in Segmente zerteilt.Deformed 1000 μm and the beam split into segments using rotating cutting beams.
Erhalten werden Teilchen mit einem Porenvolumen von 5% bis 95% im nassen Zustand. Die Möglichkeit einer Trocknung der Celluloseperlen wird erwähnt, ohne weitere Angaben in der WO 99/31 141 ist jedoch auf Grund der oben erwähnten Literatur anzunehmen, daß dabei nur ein Produkt geringer Porosität entsteht. Als Lösungsmittel für Cellulose wird in den Beispielen N-Methylmoφholin-N-Oxid (NMMO) eingesetzt.Particles with a pore volume of 5% to 95% are obtained in the wet state. The possibility of drying the cellulose beads is mentioned, but without further information in WO 99/31 141 it can be assumed on the basis of the above-mentioned literature that only a product with low porosity is produced. N-Methylmoφholin-N-oxide (NMMO) is used as a solvent for cellulose in the examples.
Ein weiteres Verfahren zur Herstellung von porösen Celluloseperlen ist in derAnother method for producing porous cellulose beads is in the
WO 02/057319 beschrieben. Auch dieses Dokument enthält keine näheren Angaben über die mögliche Trocknung der hergestellten Celluloseperlen.WO 02/057319 described. This document also does not contain any details about the possible drying of the cellulose beads produced.
In einem Beispiel (Beispiel 2) werden Perlen mit einem mittleren Durchmesser von 2,2 mm erhalten. Nach Pyrolyse der Perlen, welche auch einen Anteil an Al2O enthalten, und anschließender Sinterung haben die Perlen einen Durchmesser von 1 ,1 mm. In einem weiteren Beispiel (Beispiel 4) haben die nicht getrockneten Perlen einen Durchmesser von durchschnittlich 3,13 mm. Nach einer (nicht näher beschriebenen Trocknung) beträgt der Durchmesser nur mehr 0,8 mm. Es ist daher davon auszugehen, daß sich die Porosität dieser Perlen bei der Trocknung drastisch reduziert hat.In one example (example 2) beads with an average diameter of 2.2 mm are obtained. After pyrolysis of the beads, which also contain a proportion of Al 2 O, and subsequent sintering, the beads have a diameter of 1.1 mm. In another example (example 4), the undried beads have an average diameter of 3.13 mm. After drying (not described in detail), the diameter is only 0.8 mm. It can therefore be assumed that the porosity of these pearls has drastically reduced during drying.
Das erfmdungsgemäße Verfahren zur Herstellung von porösen cellulosischen Köipem umfaßt die Schritte Herstellen einer Celluloselosung in einem tertiären Aminoxid, insbesondere N- Methylmoφholin-N-Oxid, wobei die eingesetzte Cellulose einen durchschnittlichen Polymerisationsgrad von 150 bis 2000 hat und wobei die Lösung eine Cellulosekonzentration von 0,1 bis 5 Gew.% aufweist, Herstellen eines Köφers aus der CelluloselosungThe method according to the invention for the production of porous cellulosic bodies comprises the steps Production of a cellulose solution in a tertiary amine oxide, in particular N-methylmoφholin-N-oxide, the cellulose used having an average degree of polymerization of 150 to 2000 and the solution having a cellulose concentration of 0.1 to 5% by weight, production of a body the cellulose solution
Ausfällen des Köφers in einem Fällungsmittel, wodurch ein ausgefällter cellulosischer Köφer erhalten wird, wobei das Fällungsmittel ein wässriges Medium oder ein Cellulose fällendes, mit Wasser mischbares nicht-wässriges Medium ist, welches nicht-wässrigePrecipitation of the body in a precipitant, whereby a precipitated cellulosic body is obtained, the precipitant being an aqueous medium or a cellulose-precipitating, water-miscible, non-aqueous medium which is non-aqueous
Medium das tertiäre Aminoxid lösen kann und mit einem überkritischenMedium can dissolve the tertiary amine oxide and with a supercritical
Lösungsmittel mischbar ist und ist dadurch gekennzeichnet, daß im Falle der Verwendung eines wässrigen Mediums als Fällungsmittel im ausgefällten cellulosischen Köφer enthaltenes tertiäres Aminoxid mit dem wässrigen Medium ausgewaschen wird das wässrige Medium gegen ein mit einem überkritischen Lösungsmittel mischbares flüssiges Austauschmedium ausgetauscht wird der mit dem Austauschmedium feuchte cellulosische Köφer mit dem überkritischen Lösungsmittel behandelt wird, wodurch der poröse cellulosische Köφer erhalten wird bzw. daß im Falle der Verwendung eines nicht-wässrigen Mediums als Fällungsmittel im ausgefällten cellulosischen Köφer enthaltenes tertiäres Aminoxid mit dem nicht-wässrigen Medium ausgewaschen wird der mit dem nicht-wässrigen Medium feuchte cellulosische Köφer mit dem überkritischen Lösungsmittel behandelt wird, wodurch der poröse cellulosische Köφer erhalten wird.Solvent is miscible and is characterized in that if an aqueous medium is used as the precipitant in the precipitated cellulosic body, tertiary amine oxide contained in the precipitated cellulose is washed out with the aqueous medium, the aqueous medium is exchanged for a liquid exchange medium which is miscible with a supercritical solvent and which is moist with the exchange medium cellulosic body is treated with the supercritical solvent, whereby the porous cellulosic body is obtained or that, if a non-aqueous medium is used as a precipitant, tertiary amine oxide contained in the precipitated cellulosic body is washed out with the non-aqueous medium which is washed with the non-aqueous medium. aqueous medium moist cellulosic body is treated with the supercritical solvent, whereby the porous cellulosic body is obtained.
Unter dem Begriff „cellulosisch" sind für die Zwecke der vorliegenden Erfindung Cellulose, in tertiären Aminoxiden lösliche Cellulosederivate sowie Mischungen aus Cellulose und/oder löslichen Cellulosederivaten und anderen in NMMO löslichen Polymeren, wie z.B Polyamiden zu verstehen.For the purposes of the present invention, the term “cellulosic” means cellulose, cellulose derivatives soluble in tertiary amine oxides and mixtures of cellulose and / or soluble cellulose derivatives and other polymers soluble in NMMO, such as, for example, polyamides.
Das Auflösen von Cellulose in tertiären Aminoxiden, wie z.B. NMMO, ist aus dem Stand der Technik bekannt, wobei üblicherweise aus einer Suspension von Cellulose in einem wässrigen tertiären Aminoxid, vorzugsweise N-Methylmoφholin-N-oxid (NMMO), durch Abdampfen von überschüssigem Wasser eine Lösung von Cellulose gebildet wird.The dissolving of cellulose in tertiary amine oxides, such as NMMO, is known from the prior art, usually from a suspension of cellulose in one aqueous tertiary amine oxide, preferably N-methylmoφholin-N-oxide (NMMO), a solution of cellulose is formed by evaporating excess water.
Als überkritisches Lösungsmittel wird im erfindungsgemäßen Verfahren bevorzugt Kohlendioxid eingesetzt.Carbon dioxide is preferably used as the supercritical solvent in the process according to the invention.
Die Behandlung von Cellulose mit überkritischem Kohlendioxid wird beschrieben in:The treatment of cellulose with supercritical carbon dioxide is described in:
- EP-A 1 ,205,598 (Extraktion von Harz aus Zellstoff zur Verbesserung der Absoφtionsfähigkeit)- EP-A 1, 205.598 (extraction of resin from cellulose to improve absorption capacity)
- PCT WO 2000/015668 (Aufschluß cellulosischer Materialien mittels Dampfexplosion).- PCT WO 2000/015668 (disintegration of cellulosic materials by means of steam explosion).
Bei beiden Patenten wird von trockener Cellulose ausgegangen, es handelt sich somit nicht um die Konservierung eines hochporösen nassen Gelnetzwerkes.Both patents are based on dry cellulose, so it is not a matter of preserving a highly porous wet gel network.
Organische Lösungsmittel, die für die Zwecke der vorliegenden Erfindung als Fällungsmittel geeignet sind, sind wassermischbar, wirken gegenüber Cellulose in Aminoxidlösungen als Fällungsmittel, sind in der Lage, NMMO zu lösen, sollten eine möglichst hohe primäre Gelquellung der Cellulose bewirken und sollten mit überkritischem Kohlendioxid gut mischbar sein. Besonders geeignet sind Alkohole mit 1 - 4 C-Atomen, wie z.B. Ethanol. Als nicht-wässriges Medium bzw. als flüssiges Austauschmedium kann auch Aceton eingesetzt werden.Organic solvents which are suitable as precipitants for the purposes of the present invention are water-miscible, act as precipitants in relation to cellulose in amine oxide solutions, are able to dissolve NMMO, should cause the primary gel swelling of the cellulose to be as high as possible and should be good with supercritical carbon dioxide be miscible. Alcohols with 1 to 4 carbon atoms, such as Ethanol. Acetone can also be used as the non-aqueous medium or as the liquid exchange medium.
Das wässrige Medium, das als Fällungsmittel eingesetzt werden kann, kann aus Wasser oder aus Mischungen von Wasser mit anderen Lösungsmitteln (soferne eine die Cellulose ausfällende Wirkung beibehalten wird) bestehen.The aqueous medium, which can be used as a precipitant, can consist of water or of mixtures of water with other solvents (provided the cellulose-precipitating effect is retained).
Das Fällungsmittel (wässriges Medium oder nicht-wässriges Medium) kann zusätzlich weitere Komponenten, wie z.B. Anteile an Lösungsmittel (Aminoxid), enthalten.The precipitant (aqueous medium or non-aqueous medium) can additionally contain further components, such as e.g. Parts of solvent (amine oxide) included.
Bei der Behandlung mit dem überkritischen Lösemittel findet eine sogenannte überkritische Trockung statt. Bei der überkritischen Trocknung verschwindet die Phasengrenzfläche flüssig/gasförmig in den Poren.So-called supercritical drying takes place during the treatment with the supercritical solvent. During supercritical drying, the liquid / gaseous phase interface disappears in the pores.
Im bevorzugten Fall einer überkritischen Trocknung mit Kohlendioxid wird beispielsweise ein Alkohol- oder Aceton-feuchtes Gel in einem Autoklaven mit überschüssigem Alkohol/ Aceton bedeckt (um vorzeitige Trocknung zu verhindern), dann werden die Temperatur und der CO2-Druck langsam erhöht und einige Zeit auf Werten oberhalb des kritischen Punktes von C02 (31 ,l °C/73,8 bar) gehalten, bis das im Cellulosekörper befindliche Lösungsmittel quantitativ entfernt ist. Anschließend werden Druck und Temperatur so eingestellt, daß das CO2 in gasförmigem Zustand langsam entfernt wird.In the preferred case of supercritical drying with carbon dioxide, for example, an alcohol or acetone-moist gel is covered in an autoclave with excess alcohol / acetone (to prevent premature drying), then the temperature and the CO 2 pressure are slowly increased and for some time at values above the critical point of C0 2 (31, 1 ° C / 73.8 bar) held until the solvent in the cellulose body is removed quantitatively. The pressure and temperature are then adjusted so that the CO 2 is slowly removed in the gaseous state.
Allgemeines zur Technik der überkritischen Trocknung mit C02 siehe P. H. Tewari, A. J. Hunt, K. D. Lofftus in: J. Fricke (ed.): Aerogels (Springer Proc. Phys. 6), Springer, Berlin 1986, p. 31.General information on the technique of supercritical drying with C0 2 see PH Tewari, AJ Hunt, KD Lofftus in: J. Fricke (ed.): Aerogels (Springer Proc. Phys. 6), Springer, Berlin 1986, p. 31st
In einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens wird die Celluloselosung in an sich bekannter Weise, z.B. durch Extrusion durch ein Formwerkzeug oder durch Gießen in eine entsprechende Form, zu einem Formköφer geformt.In a preferred embodiment of the method according to the invention, the cellulose solution is processed in a manner known per se, e.g. by extrusion through a molding tool or by casting into a corresponding mold, formed into a shaped body.
Der Formköφer kann beispielsweise eine Faser, eine Folie, ein Block oder eine Platte sein.The molded body can be, for example, a fiber, a film, a block or a plate.
Aus der Celluloselosung können aber auch durch Tropfenlassen der Lösung oder beispielsweise auch durch die in der WO 99/31 141 beschriebene Technologie kugel- oder perlförmige Teilchen hergestellt werden. Weiters können aus der Lösung Teilchen mittels der Jet-Cutter-Technologie (Fa. Genialab) sowie mittels Vibrationsdüsen hergestellt werden.However, spherical or pearl-shaped particles can also be produced from the cellulose solution by dropping the solution or, for example, using the technology described in WO 99/31 141. Furthermore, particles can be produced from the solution by means of the jet cutter technology (from Genialab) and by means of vibration nozzles.
Mit dem erfindungsgemäßen Verfahren kann auch ein Pulver aus einer Vielzahl von porösen Celluloseteilchen hergestellt werden.With the method according to the invention, a powder can also be produced from a large number of porous cellulose particles.
Eine weitere bevorzugte Ausführungsform des erfindungsgemäßen Verfahrens ist dadurch gekennzeichnet, daß der cellulosische Köφer vor der Behandlung mit dem überkritischen Lösungsmittel einer Behandlung mit einem Vemetzungsmittel, wie z.B. in der WO 91/09878 beschrieben, unterzogen wird.A further preferred embodiment of the method according to the invention is characterized in that the cellulosic body is treated with a crosslinking agent, such as e.g. described in WO 91/09878.
Der nach dem erfindungsgemäßen Verfahren hergestellte, poröse cellulosische Köφer kann weiters einer Pyrolyse unterzogen werden.The porous cellulosic body produced by the process according to the invention can also be subjected to pyrolysis.
Mit dem erfindungsgemäßen Verfahren ist es erstmals möglich, einen porösen cellulosischen Köφer mit einer Porosität in trockenem Zustand von 85 % und mehr zur Verfügung zu stellen. Der durch die Behandlung mit dem überkritischen Lösemittel erhaltene Köφer ist somit ein hochporöses Aerogel. Der erfmdungsgemäße cellulosische Köφer hat bevorzugt eine Porosität von 90 % und mehr, besonders bevorzugt von 95 % und mehr. Die Porosität wird für die Zwecke der vorliegenden Erfindung wie folgt definiert: Der erhaltene cellulosische Köφer wird im Mikroskop vermessen und daraus das Volumen berechnet. Der cellulosische Köφer wird abgewogen, woraus sich die Dichte des Köφers (Masse/Volumen) ergibt. Aus der gemessenen Dichte des cellulosischen Köφers ergibt sich nach der Formel (1 - Dichte des Köφers/1 ,6) * 100 die Porosität des Köφers, d.h. der prozentuelle Anteil an Hohlräumen im Köφer. Bei einer Vielzahl von Köφern (z.B. Perlen) wird der Durchschnitt aus mehreren Messungen genommen.With the method according to the invention it is possible for the first time to provide a porous cellulosic body with a porosity in the dry state of 85% and more. The body obtained by treatment with the supercritical solvent is thus a highly porous airgel. The cellulosic body according to the invention preferably has a porosity of 90% and more, particularly preferably of 95% and more. The porosity is defined as follows for the purposes of the present invention: The cellulosic body obtained is measured in a microscope and the volume is calculated therefrom. The cellulosic body is weighed, which gives the density of the body (mass / volume). From the measured density of the cellulosic body, the formula (1 - density of the body / 1, 6) * 100 gives the porosity of the body, ie the percentage of voids in the body. In the case of a large number of bodies (eg pearls), the average is taken from several measurements.
Die Erfindung betrifft weiters einen porösen cellulosischen Köφer, der durch das erfindungsgemäße Verfahren erhältlich ist. Dieser Köφer unterscheidet sich von bekannten nach dem Aminoxidverfahren hergestellten porösen cellulosischen Köφern, wie z.B. in der WO 99/31 141 bzw. der WO 02/057319 beschrieben, dadurch, daß die Porosität in trockenem Zustand deutlich höher liegt.The invention further relates to a porous cellulosic body which can be obtained by the process according to the invention. This body differs from known porous cellulosic bodies produced by the amine oxide process, e.g. described in WO 99/31 141 and WO 02/057319, characterized in that the porosity is significantly higher in the dry state.
Erfindungsgemäße cellulosische Köφer können aufgrund ihrer niedrigen Dichte insbesondere als Isolationsmaterial, wie z.B in der thermischen oder akustischen Isolation, eingesetzt werden. Weiters können die erfindungsgemäßen cellulosischen Köφer als Dielektrikum in der Elektro- und Elektronikindustrie, zur Impedanzanpassung in akustischen Anwendungen, als Mittel zur Absoφtion und Reinigung von Gasen, als Träger für Katalysatoren und/oder als Mittel zur Speicherung von Energieträgern, wie z.B. Wasserstoff, eingesetzt werden.Due to their low density, cellulosic bodies according to the invention can be used in particular as insulation material, for example in thermal or acoustic insulation. Furthermore, the cellulosic bodies according to the invention can be used as a dielectric in the electrical and electronics industry, for impedance matching in acoustic applications, as a means for absorbing and cleaning gases, as a carrier for catalysts and / or as a means for storing energy sources, such as e.g. Hydrogen.
Die Erfindung betrifft weiters einen porösen Kohlenstoffköφer, der aus dem erfindungsgemäßen cellulosischen Köφer mittels Pyrolyse erhältlich ist.The invention further relates to a porous carbon body which can be obtained from the cellulosic body according to the invention by means of pyrolysis.
Für diese Kohlenstoffköφer eröffnen sich besonders interessante Einsatzgebiete. Das nach Pyrolyse des Celluloseanteils resultierende Kohlenstoff-Aerogel ist als Elektrodenmaterial für Batterien, Akkumulatoren, Kondensatoren und Brennstoffzellen sowie zur Hochtemperaturisolierung geeignet. Gleichzeitig stellen solche Kohlenstoff-Aerogele in Analogie zu Kohlenstoff-Nanoröhren effiziente Wasserstoffspeicher dar.Particularly interesting areas of application open up for these carbon bodies. The carbon airgel resulting after pyrolysis of the cellulose component is suitable as an electrode material for batteries, accumulators, capacitors and fuel cells and for high-temperature insulation. At the same time, such carbon aerogels, in analogy to carbon nanotubes, represent efficient hydrogen stores.
Beispiel:Example:
Es wurde auf an sich bekannte Weise eine Celluloselosung mit 1 Gew.%> Cellulose (Zellstoff Solucell mit einer Viskosität nach SCAN CM 15:88 500) / 82 Gew.% NMMO / 17% Gew.H2O hergestellt. Diese Lösung wurde in Wasser als Fällungsmittel tropfen gelassen, das Lösungsmittel mit Wasser ausgewaschen und anschließend das Wasser gegen Ethanol ausgetauscht.A cellulose solution with 1% by weight> cellulose (cellulose Solucell with a viscosity according to SCAN CM 15:88 500) / 82% by weight NMMO / 17% by weight H 2 O was prepared in a manner known per se. This solution was dropped in water as a precipitant Washed out solvent with water and then exchanged the water for ethanol.
Die Ethanol-feuchten Köφer (Kugeln mit ca. 3 mm Durchmesser) wurden in einen Autoklaven gegeben, mit zusätzlichem Ethanol bedeckt, auf 50°C aufgeheizt und während 2,5 Stunden 130 bar CO2 aufgegeben. Das CO2 wurde im Kreislauf gefahren, wobei im Kreislauf der Druck in zwei Stufen mit jeweils einem Flüssigkeitsabscheider auf 60 bzw. 40 bar reduziert wurde, anschließend wurde das C02 wieder auf 130 bar komprimiert. Nach den genannten zweieinhalb Stunden wurde bei 50°C dann das C02 abgelassen.The ethanol-moist bodies (spheres with a diameter of approximately 3 mm) were placed in an autoclave, covered with additional ethanol, heated to 50 ° C. and 130 bar of CO 2 were added for 2.5 hours. The CO 2 was kept in circulation, which was reduced in the cycle of pressure in two stages, each with a liquid at 60 and 40 bar, then the C0 2 has been re-compressed to 130 bar. After the two and a half hours mentioned, the CO 2 was then discharged at 50.degree.
Es wurden Cellulosekugeln erhalten mit demselben Durchmesser (ca. 3 mm) wie das feuchte Ausgangsprodukt. Die Dichte der Cellulosekugeln betrug 0,042 g/cm3; das bedeutet gemäß obiger Berechnungsformel, daß das Porenvolumen 97,4% beträgt. Cellulose balls with the same diameter (approx. 3 mm) as the moist starting product were obtained. The density of the cellulose balls was 0.042 g / cm 3 ; according to the above calculation formula, this means that the pore volume is 97.4%.
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DE102006049179B4 (en) * | 2006-10-18 | 2016-07-07 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Aerogels, process for their preparation and their use |
DE102010011808A1 (en) | 2010-03-18 | 2011-11-17 | Blue Globe Energy Gmbh | Porous solid body made of cellulose phosphate and carrying covalently bound phosphate groups on its entire surface and inner surface, useful as a cell growth substrate including bone implant- or cartilage- and bone regeneration-material |
DE102013111459A1 (en) * | 2013-10-17 | 2015-04-23 | Elringklinger Ag | Acoustically effective shielding parts and covers |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1575700A (en) * | 1976-04-22 | 1980-09-24 | Purdue Research Foundation | Porous cellulose beads |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3553132A (en) * | 1968-02-26 | 1971-01-05 | Celanese Corp | Heat and flame resistant pyrolyzed cellular material and process of making same |
US5169687A (en) * | 1988-09-16 | 1992-12-08 | University Of South Florida | Supercritical fluid-aided treatment of porous materials |
DE19755353C1 (en) * | 1997-12-14 | 1999-04-29 | Thueringisches Inst Textil | Production of porous cellulose beads |
ATE293138T1 (en) * | 1997-12-14 | 2005-04-15 | Thueringisches Inst Textil | METHOD FOR PRODUCING REGULAR POROUS PEARL CELLULOSES |
DE10102334C2 (en) * | 2001-01-19 | 2003-12-04 | Thueringisches Inst Textil | Process for the production of regular, monodisperse cellulose beads and their use |
-
2003
- 2003-01-20 AT AT0007103A patent/AT412404B/en not_active IP Right Cessation
-
2004
- 2004-01-19 WO PCT/AT2004/000013 patent/WO2004065424A1/en active Application Filing
- 2004-01-19 EP EP04703120A patent/EP1585772A1/en not_active Withdrawn
- 2004-01-20 TW TW093101667A patent/TW200418558A/en unknown
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1575700A (en) * | 1976-04-22 | 1980-09-24 | Purdue Research Foundation | Porous cellulose beads |
Non-Patent Citations (1)
Title |
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See also references of WO2004065424A1 * |
Also Published As
Publication number | Publication date |
---|---|
AT412404B (en) | 2005-02-25 |
TW200418558A (en) | 2004-10-01 |
WO2004065424A1 (en) | 2004-08-05 |
ATA712003A (en) | 2004-07-15 |
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