The method of obtaining copper-aluminum spinel extrudates

 

The invention concerns a method of obtaining copper-aluminum spinel extrudates, in particular extrudates in the form of honeycombs, which after drying and calcination can be used as catalysts. Describes how to obtain a copper-aluminum spinel extrudates by extrusion of a powder of copper-aluminum spinel, and, if necessary, and auxiliary equipment used for compaction, stabilizers, antisodomy means of pore or molding masses, containing a mixture of the original molding composition further comprises oxides of aluminum or hydrates of aluminum oxide and nitrates of metals in a weight ratio corresponding to the weight ratio of copper-aluminum spinel, and the calcination is carried out at temperatures in the range from 700 to 900o. Also described products in the form of cell profiles obtained by the method described above, where the initial extrudate is dried at temperatures in the range from 10 to 2000oWith or sublimate at temperatures in the range from minus 40 to 0oC at a pressure of from 0.05 to 0.8 bar and calicivirus at temperatures in the range from 500 to 900oEffect: getting a flat, undeformed products is Stateline to changing thermal loads. 2 S. and 6 C.p. f-crystals, 1 table.

The present invention relates to a method of producing spinel extrudates, in particular extrudates in the form of honeycombs, which after drying and calcination can be used as catalysts.

Combustion of hydrocarbons with air used as the oxidant, the oxidation of nitrogen contained in the air are formed, especially when the excess air and at high temperatures, nitrogen oxides. Examples of such oxides are NO, NO2, NO3N2About3N2O4and N2O5. To prevent pollution of these oxides of nitrogen as harmful substances should be as short as possible removed from the exhaust gases. And when you consider that harmful emissions from industrial plants and CHP dramatically reduced through the use of purification of exhaust gases, it is becoming increasingly important problem of reducing the content of harmful substances in exhaust gases of vehicles and, primarily, on the basis of increasing the number of vehicles themselves.

To reduce emissions of nitrogen oxides from automobile engines was proposed many solutions. Effectively the congestion should for example, be provided by: - a high degree of conversion, i.e. a significant removal of nitrogen oxides that must be guaranteed at high and low temperatures, frequent changing loads during operation, the possibility of preventing the use of auxiliary reagents such as ammonia or urea, low operating and maintenance costs - long service life - the formation of minor amounts of nitrous oxide, high mechanical strength of the catalyst.

The number of known catalysts used to reduce oxides of nitrogen. This is one of the areas of development of the respective catalysts are aimed at creating catalysts made on the basis of spinel.

The use of spinel ul2O4impregnated with copper as a catalyst exhaust gas described in the patent application Germany And 19546482. These spinels are used in the form of crumbs.

And in the application for a European patent A-0779093 also described respective catalysts from spinel to reduce the content of nitrogen oxides and oxidation of hydrocarbons. These spinels is made on the basis of zinc, copper and aluminum and are used in the form of crumbs.

In the application for Europe is lobnig gases, reducing the content of nitrogen oxides. We are talking about the zinc-lomaspilis, which can be obtained from the original solution by precipitation. The products of deposition can be dried using a spray drying or flash evaporation of the solvent and isolated in powder form. You can also mix the original solution of the catalyst, for example, with urea or glycine and burn this mixture, along with the formation of spinel as a result of high temperature, there is a simultaneous calcination of the product. Indicates that the catalysts can be obtained in the form of honeycombs, but do not specify a technological method by which this can be accomplished.

Catalysts made of spinel, used cars mostly not in the form of chips or pellets, and in the form of honeycombs, consisting of a material of catalyst and having a mainly parallel channels through which the treated exhaust gases. Such cells may fit in the context, for example, bee satam. Individual channels may be circular or rectangular, in particular square cross-section, resulting in a cross-section of these hundred corresponds to a rectangular lattice structure.

Were pre whom I oxide compounds TiO2-SiO2that, in addition, may also contain zirconium dioxide. To do this, mixed with an aqueous solution containing active components such as vanadium and copper, or a powder of the active components in the form of oxides, together with a molding material such oxide containing titanium as TiO2, TiO2-SiO2and TiO2-SiO2-ZrO2. Then these components mix, adding appropriate amount of water, after which the mixture formed in the extruder device. The resulting product is dried and subjected to calcination.

Patent application Germany And 4419974 relates to a method of obtaining a molded catalyst based on titanium dioxide and its application. This catalyst can be obtained in the form of honeycombs. To obtain soda mix titanium dioxide in powder form in a mixture with water, ammonium solution metavolume, polyethylene glycol as a plasticizer, monoethanolamine and fiberglass. This homogeneous mix mass is formed into the extruder in cell profiles, after which the catalyst honeycomb is dried and subjected to calcination.

U.S. patent 5219816 relates to dehydrogenation catalysts and methods for their preparation. To obtain material the resulting mass in the extruder with obtaining relevant profiles. After drying, you calcination at temperatures from 600 to 700oC.

Manufacturing cell profiles, in particular, of copper-aluminum spinel, known methods involves a number of disadvantages.

Making hundreds of moulding mass in the extruder requires a long time in accordance with a low feed rate of the material. Often the feed rate of the material is from 5 to 10 cm per minute.

Drying time obtained on extruder hundred very large. At room temperature it is often not less than one month.

During drying and subsequent calcination, as a rule, there are various strain - for example, a parallelogram and a pillow and longitudinal and transverse cracks. Increase the drying time does not improve the results.

Such cells due to the presence of cracks and deformations are not mechanically stable and do not provide uniform gas flow through the catalyst, resulting in the permanent establishment of reaction conditions on catalyst is difficult or impossible. Furthermore, for example, catalysts in the form of honeycombs must be for the possibility of their use on vehicles consistent in shape with the body, in notorious, resulting exhaust gases as if by-pass by-pass the catalyst, in General, dramatically reducing its performance. Thus, with a total consideration in this case, the catalyst has a lower activity.

The purpose of this invention is to provide a method of producing spinel extrudates, in particular, in the form of honeycombs, not having the disadvantages of the known technological methods and providing a flat, undeformed products, no cracks, but has a high mechanical stability and longer durability and which is insensitive to thermal loads. They must enter into various parts, for example in housing, providing maximum activity during the operation. In addition, this method of manufacture should be faster compared with conventional methods.

In accordance with the claimed invention this problem is solved by a method of producing extrudates from a powder of spinel, and, if necessary, of the AIDS used during pressing, stabilizers, antisodomy means, pore, peptizyme funds or of the moulding mass containing a mixture thereof, followed by drying the hydrate of aluminum oxide and nitrates of metals. Preferred is the use of nitrates of metals with acidic aqueous solutions. Especially preferred is the use of nitrate of copper. Instead preferred si(NR3)23H2About can be used also hydrates with a smaller or greater number of moles of water of crystallization. In addition, can also be used and other nitrates of metals, provided that their cations are spinlooptime and that the presence of a catalyst formed of metal oxides is desirable.

This molding material is manufactured by extrusion in the main cell profiles, already described in the beginning. Typical cell profiles have channels with a diameter of from 1 to 5 mm in thickness, partitions separating them from 0.2 to 5 mm

The claimed method makes it possible to manufacture the spinel hundred without deformations and cracks. The flow of the molding material for manufacturing the honeycomb can be carried out at a speed of 80 cm / min. Drying time at room temperature is typically only one week. Manufactured cells have a very high mechanical stability and stability to changes in temperature loads.

the corresponding powders of spinel described, for example, in applications for a European patent A-0676232 And 0779093, in the patent application Germany And 19546482, and having an earlier priority, not previously published patent application Germany And 19653200.

Spinel is described, for example, K. C. of Correns in "Introduction to Mineralogy", publisher shpringer, 1949, pages 77-80. Other descriptions are, Remy, "a Textbook of inorganic chemistry", Academic publishing house "Geest and Portig KG, Leipzig 1950, pp. 308-311, and Rempe, "Chemical encyclopedia, 9th edition, 1995, pp. 4245. Formally spinels originate from lumasense MgAl2O4. While magnesium can be replaced by ions such other divalent metals, such as zinc, copper, iron. The aluminum can be replaced by ions such other trivalent metals, such as iron or chromium. In the structural lattice of the spinel oxygen atoms form a dense cubic packing in accordance with centered in the plane of the grating. One half of the octahedral voids in it is occupied by the aluminum, the other half of the cavities not occupied. One-eighth of the tetrahedral voids are occupied by magnesium.

Mainly as a powder using copper-lomaspilis powder, which can be produced by the substitution in Diana, the molybdenum trioxide, titanium dioxide, vanadium pentoxide, niobium trioxide, lanthanum trioxide or mixtures thereof and which can additionally be introduced precious metals.

Mostly use the spinel powders with an average grain size of the particles is from 0.1 to 50 μm, preferably from 1 to 30 μm, particularly preferably from 2 to 10 μm. They can be obtained in various ways, as, for example, it's mentioned in earlier publications.

Preparation of powders of spinel can be carried out, for example, by mixing powdered oxides contained in the spinel metal, pressing these mixtures of oxides and callerebia. The temperature of calcination is generally not less than 700oC. as used oxides can be considered, for example, zirconium dioxide, silicon oxide, aluminum oxide, titanium dioxide, cesium dioxide, tin dioxide, tungsten trioxide, molybdenum trioxide, niobium trioxide, lanthanum trioxide and vanadium pentoxide.

Preparation of powders can also be performed by mixing solutions of salts of the metals contained in the spinel, with subsequent operations deposition, drying and calcination. Instead of the solution can be COI inorganic salts, as nitrates, sulfates, carbonates or halides. But can also be used, and organic acid salts such as formate, acetate, propionate, oxalates or citrates. The deposition may be due to additive coagulants type ammonia, alkaline carbonates, basic alkaline carbonate or hydroxide.

In addition, the solutions can be dried and converted into powder form using a spray drying or flash evaporation. After drying can be accomplished by calcining, mainly at temperatures of at least 600oC.

In addition, compounds containing the original metal spinels, can be mixed with a source containing carbon and nitrogen, after which the resulting mixture is burned, creating a high temperature, causing the formation of spinel. As such a source of carbon and nitrogen may be considered, for example, organic compounds of the type of urea or glycine.

Other commonly used methods of preparation are described, for example, in the patent application Germany And 4224881. For example, oxides of metals of the type lOO (boehmite), copper oxide, zinc oxide, and, if necessary, and other suitable metal oxides may be in the presence of some of the relations is ROFILE can be converted into powder form. Instead of metal oxides can be used corresponding hydroxide, oxyhydrates, carbonates, organic acid salts, nitrates, chlorides, sulphates or phosphates, as described above. For manufacturing bicistronic or polycistronic catalysts can be used instead of the hydrate of aluminum oxide mixture consisting of hydrate of aluminum oxide and aluminum oxide, mainly fromor-aluminum oxide. This can be used alumina with different pore sizes.

Drying is carried out generally at temperatures in the range from 10 to 200oC, preferably from 20 to 150oS, particularly preferably from 30 to 120oC. Possible and freeze-drying (for example, from minus 40 to 0oC at a pressure of from 0.05 to 0.8 bar). This method is the most gentle, though requiring more time. This well preserved geometric shape. The calcination is produced mainly at temperatures from 600 to 900oC.

When using known technologies powder of spinel, or a mixture of the original salt obtained as described above, push on the extruder to obtain cellular profilelist along with supporting means, used during pressing, stabilizers, antisodomy means, pore, patiserie means or forming masses, with their mixtures, oxides or hydroxides of aluminum oxide and nitrates of metals. While the hydrate of aluminum oxide and, for example, copper nitrate are mainly used in a molar ratio of from 0.3 to 0.7, preferably from 0.4 to 0.6. As the hydrate of aluminum oxide are used in the main hydroxide aluminum oxide, trihydroxide aluminum or mixtures thereof. Metal salts can be used in the form of their hydrates. The preferred content of the hydrate of aluminum oxide and the metal nitrate is from 15 to 55 wt.% from a quantity of powder of spinel. The spinel powder kneaded with additional components to a plastic mass, which is then processed into extrudates, in particular in cellular profiles. Then the extrudate is dried at temperatures generally in the range from 10 to 200oC, preferably from 20 to 150oS, particularly preferably from 30 to 120oWith, and subjected to calcination in the temperature range from 500 to 900oC. Additive hydrate of aluminum oxide and metal nitrate provides the possibility of obtaining products in the form of a cell

Preferably the ratio of the number of hydrate of aluminum oxide to the metal nitrate (copper) is chosen so that it corresponds with the quantitative ratio in spinel. For a given powder mainly taken from 5 to 25 wt.% hydrate of aluminum oxide and from 10 to 30 wt.% the metal nitrate (e.g., si(NO3)23H2About). The molar ratio of metal oxide to aluminum oxide in this original form spinel should not be substantially below stoichiometric. Basically it should be somewhere between 0.6 to 1.4.

Instead lOO (boehmite) can also be used Al(Oh)3(bayerite or hydro-argillite) or other hydrates of alumina, and mixtures thereof. According to the description of the possible diversity of hydrate of aluminum oxide can be given a reference to a publication Holleman-Wiberg, "a Textbook of inorganic chemistry", Walter D. Gruyter Berlin, new York, 1985.

Mainly used boehmite and nitrate of copper with a water content of from 2 to 6 moles.

The preparation used powder of spinel can be performed in various ways, for example: - joint precipitation of the hydroxide with subsequent calcination, the mixture of oxides with subsequent calcination, is used in the s,
- mix salt with subsequent spray drying, and calcining.

In the spinel powder and obtained from him the extrudates, in particular, cells may be introduced and such other oxides, as the dioxide of zirconium, cesium dioxide, tin dioxide, tungsten trioxide, molybdenum trioxide, titanium dioxide, vanadium pentoxide, niobium trioxide, lanthanum trioxide and/or noble metals of the type of platinum, palladium, ruthenium, silver, gold. These supplements are taken mainly in the range from 0 to 10 wt.% from mass calcinatory hundred.

Extrusion of the molding material for the manufacture of products in the form of cell profiles produced in accordance with the claimed method is mainly speeds up to 80 cm per minute. Drying time at room temperature is in accordance with the claimed invention mainly about one week.

Manufactured in accordance with the claimed invention of the product in the form of cell profiles can be used as catalyst or catalyst carrier in the catalytic purification of exhaust gases from nitrogen oxides. Thus, they are assumed to be primarily for the removal of nitrogen compounds in the fuel gas, mainly from diesel engines. But they mohani coal, oil or debris. With appropriate use of cell catalysts assume also possible and purification of industrial exhaust gases containing nitrous oxide. Also, with appropriate use of titanium dioxide, vanadium pentoxide and tungsten trioxide possible and decomposition of dioxin, which can be performed simultaneously with the removal of nitrogen oxides or directly after it. Basically decomposition of dioxin can be done in terms of oxidation catalyst containing titanium dioxide, vanadium pentoxide and tungsten trioxide, as described in the application for a European patent A-0447537. Can be cleaned and other waste gases containing polyhalogenide connection. Especially preferably the use of cellular profiles - in particular, containing a noble metal as a media adsorption is carried hydrocarbon catalysts for full use.

The present invention is explained below based on examples.

Examples
Example 1
Source material
Take 3000 g of copper powder-lumasense, in which the copper content is undervalued against stoichiometric. He has a 6% loss on ignition, h,1 mol of aluminum oxide. Thus, it contains of 0.32 mol of copper per mole of aluminum oxide, being thus clearly below the stoichiometric range. The spinel powder may be original, fresh, cooking or recycling of, for example, in the current process. Fresh powder is prepared according to the method described in the application for the European patent A-0676232, example 2, namely by mixing copper nitrate and hydroxide of aluminum with water, followed by spray drying in a known manner, and calcining at 800oC.

Adulteration of additives lOO+Cu(NO3)23H2O.

3000 g of the specified spinel powder is mixed with a mixture of 402,8 g wet Pural" (mineralogicheskii defined as boehmite=lOO containing 73,74% = 297,0 g = 2.9 moles in terms of aluminum oxide) and 703 g of three-hydrate of copper nitrate (232 g = 2.9 moles in terms of oxide of copper). The mixture is equimolecular, that is, corresponds in composition to the formula CuAl2O4.

Mixing
A mixture of spinel powder and additives to the mixture contains 796 g = 10,0 moles in terms of oxide of copper and 2553 g = 25,0 of moles in terms of aluminum oxide. Thus, the molar ratio of copper oxide to aluminum oxide sostav the t for 5 minutes. Then add 246,4 g carbon fiber, 41 g "Walocel(hydroxymethylcellulose), 41 g of polyethylene oxide and 2000 g of fully demineralized water and mix this weight within 6 hours. Then added 41 g of monoethanolamine and mix it for another 7 hours. At the time of kneading add 350 grams of evaporated water. Carbon fibers have a length of 3 mm and a diameter of 5 microns.

Manufacturing cell profiles
Cell profiles ekstragiruyut, dried and calicivirus on conventional extruders under the following operating conditions.

The extrusion speed of 50 cm / minute
Drying time - 8 days
Appearance calcinatory hundred - impeccable
Tensile strength is the resistance to punching shear 181 N/cm2
Stability when the temperature is very high
The catalytic activity is very high, in this case 100%.

Example 2 (comparative)
The production in situ of the three-hydrate of copper nitrate and boehmite.

4841 g of Cu(NO3)23H2Oh, 9482 g of AlOOH, 522 g of carbon fibers, 128 g of monoethanolamine, 128 g of lactic acid, 96 g of carboxymethyl cellulose and 5020 g of water is stirred and mix very similar to these procedures in example 1. The resulting mass izgotovlivala drying - 28 days
Resistance to bursting - 50 N/cm2
The catalytic activity of 80% specified in example 1
Appearance - a large number of longitudinal cracks, severe deformity
Stability during temperature change - the presence of additional cracks.

Example 3
Analogously to example 1, but with cordierite, but without auxiliary tools used during pressing and without pore.

The spinel powder and lOO, and C(NR3)23H2About mixed as described in example 1, add 12% of cordierite and 30% water and processed into cell profiles with a density of 160 cells per square inch.

The extrusion speed is 45 cm per minute
The drying time is 10 days
Resistance to bursting - 150 N/cm2
The catalytic activity of 95% from that indicated in example 1
Appearance - light, longitudinal cracks, honeycombs have specified dimensions
Stability when the temperature is high.

Example 4
Analogously to example 1, but using cordierite. In contrast to example 3 in this case, used tools, used during compaction, and pore.

Material costs are presented in the table.

Soon the lytic activity - 100% specified in example 1
Appearance is impeccable
Stability when the temperature is high.


Claims

1. The method of obtaining copper-aluminum spinel extrudates by extrusion molding masses containing powder of copper-aluminum spinel and, if necessary, auxiliary tools used during extrusion, stabilizers, antisodomy tools, pore, or a mixture thereof, followed by drying and calcining these extrudates, wherein the molding composition further comprises oxides of aluminum or oxide hydrates of aluminium and copper nitrate in a weight ratio corresponding to the weight ratio of copper-aluminum spinel, and the calcination is carried out at temperatures in the range from 700 to 900C.

2. The method according to p. 1, characterized in that the molding material by extrusion manufacture of the product cell structure.

3. The method according to p. 1 or 2, characterized in that, as a powder using a powder of copper-aluminum spinel, which can be from 0 to 10 wt.% replaced by the dioxide of zirconium, cesium dioxide, tin dioxide, tungsten trioxide, molybdenum trioxide, Vuokatti precious metals.

4. The method according to one of paragraphs.1-3, characterized in that the hydrate of aluminum oxide and nitrate of copper is used in a molar ratio of Cu:Al from 0.3 to 0.7.

5. The method according to one of paragraphs.1-4, characterized in that as a hydrate of aluminum oxide using a hydroxide of aluminum oxide, trihydrates aluminum or a mixture of them.

6. The method according to one of paragraphs.1-5, characterized in that the amount of hydroxide of aluminum oxide and nitrate of copper, calculated by lO and Cu(NO3)23H2O, is from 15 to 55 wt.%, take the number of spinel powder.

7. The method according to p. 6, wherein the boehmite and the nitrate of copper is used with a moisture content of from 2 to 6 moles.

8. Products honeycomb structure obtained by the method according to one of paragraphs.1-7, characterized in that the source of the extrudate is dried at temperatures in the range from 10 to 200°C or sublimate at temperatures in the range from minus 40 to 0°C at a pressure of from 0.05 to 0.8 bar and calicivirus at temperatures in the range from 700 to 900°C.

 

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