Composition based on zirconium oxide, yttrium oxide and tungsten oxide, method of production and use as catalyst or catalyst support. RU patent 2440299.
 Tungstic acid powder consisting of spherical particles and method of preparing said powder / 2389690Invention can be used in tungsten metallurgy. A solution of an alkali metal and a solution of an inorganic acid are continuously fed into a reactor or cascade of reactors in molar ratio of an inorganic acid to tungstate ranging from 4:1 to 9:1 while stirring continuously. Sodium tungstate is mainly used as the alkali metal tungstate and the mineral acid used is a solution of sulphuric acid containing 50-70 wt % H2SO4. Tungstic acid powder has apparent density in accordance with ASTM B 329 of at least 1.5 g/cm3 and can be used to make tungsten metal powder. |
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Method of obtaining high-purity tungsten oxide (iv) / 2341461 Proposed method of obtaining high-purity tungsten oxide (IV) involves hydrolysis of pure tungsten hexafluoride with subsequent separation of tungsten oxide from the solution of hydrolysis products and baking of the latter. Tungsten hexafluoride is purified by distillation with subsequent filtering of the tungsten hexafluoride stream through a fluoroplastic fibrous filter. Distillation of tungsten hexafluoride is carried out with rate of evaporation not exceeding 5·10-4 g/(cm2·s), and filtration is carried out when the stream of gaseous tungsten hexafluoride passes through a filter at linear speed of 0.3-1 cm/s. The separated tungsten oxide is baked in a stream of oxygen at 400-900°C. |
 Zirconium hydroxide / 2434810Invention relates to chemistry and can be used in catalytic processes. Amorphous zirconium hydroxide has surface area of at least 300 m2/g, total pore volume of at least 0.70 cm3/g and average pore size from 5 nm to 15 nm. First, an aqueous solution containing sulphate anions and a zirconium salt with the ratio ZrC2:SO3 ranging from 1:0.40 to 1:0.52 are obtained. The solution is then cooled to temperature lower than 25°C. Alkali is then added to precipitate amorphous zirconium hydroxide which is then filtered and washed with water or alkali to remove residual sulphate and chloride. The washed residue undergoes thermal treatment at excess pressure of not less than 3 bars and dried. |
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Method of producing mineral material using zirconium oxide grinding beads containing cerium oxide, obtained products and use thereof / 2432376 In order to obtain ground mineral material a) at least one mineral material which is optionally in form of aqueous suspension is taken, b) said material is ground, c) the ground material obtained at step (b) is optionally sieved and/or concentrated, d) the ground material obtained at step (b) or (c) is optionally dried. The grinding step (b) is carried out in the presence of zirconium oxide grinding beads containing cerium oxide, having cerium oxide content between 14 and 20% of the total weight of said beads, preferably between 15 and 18% of the total weight of said beads, and more preferably approximately 16% of the total weight of said beads. The average size of grains after sintering grains which form said beads with average diameter less than 1 mcm is preferably less than 0.5 mcm and more preferably less than 0.3 mcm. The obtained ground mineral material is in form of aqueous suspension, wherein the weight ratio ZrO2/CeO2 is equal to 4-6.5, preferably 4.6-5.7 and more preferably 5.3. |
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Method of producing nanocrystalline powder of metal oxides / 2425803 Method involves production of metal hydroxides via reverse precipitation, drying and calcination. To prevent local change in pH of the solution of the precipitation agent, the reverse precipitation method involves ultrasonic treatment of the solution of metal salts in an atomising nozzle through which the said solution passes before reacting with the solution of the precipitation agent. The solution of metal salts undergoes ultrasonic treatment which enables to disperse the solution to droplets with size smaller than 1.0 mcm. |
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Composition for making thin films based on system of double oxides of zirconium and zinc / 2411187 Invention relates to production of thin-film materials used in illumination, construction and electronics. The composition for making thin films based on a system of double oxides of zirconium and zinc contains the following components, wt %: zirconium oxochloride 4.0-8.6; zinc nitrate 3.8-7.6; pre-distilled and dried to 96 wt % ethyl alcohol - the rest. The film-forming solution of the said composition is deposited onto a substrate by centrifuging and subjected to step-by-step thermal treatment. |
 Method of obtaining nanodispersed metal oxides / 2407705Invention can be used in production of refractory ceramic matrices of composite materials and high-temperature coatings. A solution of β-diketonates of one or more metals with concentration of 1·10-3-1 mol/l in an organic solvent or mixture of solvents in the presence of an alcohol undergoes thermal treatment at 95-250 °C for 0.1-8 hours to obtain solutions of alkoxo-β-diketones of corresponding metals. Hydrolysis is then carried out at 15-95°C for 0.05-240 hours with hydrolysing solutions, which are either water, organic solvents or mixture of solvents containing water or a mixture of organic solvents and water to form transparent gels. Further, the gels are dried at 15-250°C and pressure of 1·10-4-1 atm until constant weight. Thermal treatment of xerogels to form nanocrystalline metal oxides is carried out in an oxygen-containing atmosphere at 350-750°C for 0.5-24 hours. |
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Zirconium oxide- and cerium oxide based composition with increased reducing power and stable specific surface, method of its producing and using for exhaust gas treatment / 2407584 Invention can be used for exhaust gas after burning in ICE. Aqueous mix containing zirconium and cesium and one of lanthanides, ether than cerium, and yttrium is obtained. Obtained mix is heated to 100 °C to produce precipitate in the form of suspension in reaction medium which is brought up to the level of alkaline pH. First, added is additive selected from anion surfactants, nonionic surfactants, polyethylene glycols, carbonic acids and their salts, and surfactants of the type of carboxymethylated oxethylates of fat alcohols is added to produced medium and, then precipitate is separated. In compliance with another version, first, precipitate is liberated from reaction medium and, thereafter, aforesaid additive is added to precipitate. Precipitate is calcinated in atmosphere of inert gas or in vacuum at 900 °C and, then in oxidising atmosphere at 600 °C. Produced composition contains cerium oxide in amount of not over 50 wt %. Reduction degree after calcination in atmosphere of air at 600 °C makes at least 95 %, while specific surface after calcination at 1100 °C for 4 h makes at least 15 m2/g. |
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Composition for making thin film based on system of double oxides of zirconium and titanium / 2404923 Invention can be used in electronic engineering, lighting and construction industry. The composition is obtained by preparing a film-forming solution based on 96 wt % ethyl alcohol, 6.68-10.02 wt % crystalline hydrate of zirconium oxochloride and 3.34-5.01 wt % tetraethoxytitanium. The obtained solution is deposited onto a substrate and thermally treated. |
 Method of preparing zirconium dioxide nanopowder / 2404125Zirconium hydroxide is precipitated and then simultaneously dried and calcined under microwave radiation in the frequency range 50-20000 MHz with continuous power of 3.0-50.0 kW for 5-60 minutes. |
 Method of producing zirconium oxide having tetragonal modification for producing catalysts / 2400429Invention relates to methods of producing zirconium oxide used in chemistry for producing catalysts. The invention describes a method of producing zirconium (IV) oxide for producing catalysts involving preparation of an initial reaction aqueous solution of a zirconium (IV) salt, precipitation of zirconium hydroxide from the solution, separation of the obtained zirconium hydroxide precipitate from the aqueous solution, drying and calcination of the precipitate at 600°C. The method is characterised by that precipitation is carried out using an anionite in OH form. |
 Zirconium-bearing raw material processing method / 2386713Invention refers to processing of zirconium-bearing natural raw material, namely zirconium concentrate, and can be used for obtaining microdispersed high-purity zirconium dioxide. Processing method involves fluoridisation of zirconium-bearing raw material, heat treatment of fluoridised product so that zirconium tetrafluoride is obtained, and its further pyrohydrolysis. Fluoridisation is performed by treatment of zirconium-bearing raw material with 10-20% solution of hydrofluoric acid with conversion of zirconium compounds to the solution, separation of solution from the formed settlement, addition of ammonium fluoride to the obtained solution with further extraction of deposited fluoridisation product. Heat treatment of the extracted fluoridisation product so that zirconium tetrafluoride is obtained is performed by thermal decomposition at 600-650°C with separation of ammonium fluoride and removal of ammonium hexafluorosilicate by distillation. Pyrohydrolysis of zirconium tetrafluoride is performed in gas phase. |
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Method of producing alcohol solvates of chlorides of rare-earth elements / 2438981 Invention can be used in chemical industry when producing diene polymerisation catalysts. Aqueous chloride of a rare-earth element is mixed with monoatomic alcohol in molar ratio alcohol: rare-earth element equal to (100-200):1. The azeotropic mixture is distilled at normal pressure, followed by distillation of excess alcohol in the presence of paraffin with initial boiling point of 220-270°C in a rotary film evaporator. The ready product is a stable mobile dispersion of a solvate of a chloride of a rare-earth element in liquid paraffin. |
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Method of producing powdered trisulphides of europium, lanthanide and copper / 2434809 Invention relates to inorganic chemistry and specifically to a method of producing complex sulphides of rare-earth elements used as semiconductor materials. The method of producing powdered trisulphides of europium (II), lanthanide (III) and copper EuLnCuS3 (Ln=La-Lu) involves exposing an initial charge of an argon stream to sulphiding gases (H2S, CS2), obtained from decomposition of ammonium rhodanide. The initial charge used is a mixture of simple and complex oxides obtained via thermal decomposition at 1000 K together with crystalline nitrates of copper, europium and lanthanide. Sulphidation takes place in a stream of H2S and CS2 (4-6 eq/l) at 970 K for 15 hours, at 1120 K for 7 hours and at 1220 K for 3 hours. |
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Method of producing mineral material using zirconium oxide grinding beads containing cerium oxide, obtained products and use thereof / 2432376 In order to obtain ground mineral material a) at least one mineral material which is optionally in form of aqueous suspension is taken, b) said material is ground, c) the ground material obtained at step (b) is optionally sieved and/or concentrated, d) the ground material obtained at step (b) or (c) is optionally dried. The grinding step (b) is carried out in the presence of zirconium oxide grinding beads containing cerium oxide, having cerium oxide content between 14 and 20% of the total weight of said beads, preferably between 15 and 18% of the total weight of said beads, and more preferably approximately 16% of the total weight of said beads. The average size of grains after sintering grains which form said beads with average diameter less than 1 mcm is preferably less than 0.5 mcm and more preferably less than 0.3 mcm. The obtained ground mineral material is in form of aqueous suspension, wherein the weight ratio ZrO2/CeO2 is equal to 4-6.5, preferably 4.6-5.7 and more preferably 5.3. |
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Method of extracting lanthanides from apatite concentrate / 2430885 Apatite concentrate is decomposed with nitric acid to obtain nitrate-phosphate solution. Calcium nitrate and sodium fluosilicate are successively extracted from the solution. The solution is neutralised with ammonia to form a precipitate of phosphates of the main part of lanthanides and a mother solution with the residual part of lanthanides. The mother solution is treated by bringing it into contact with an amorphous titanium phosphate-based sorbent at pH of the solution equal to 1.4-1.7 with concentration of the residual part of lanthanides in the sorbent. The lanthanide-rich sorbent is separated, washed with water and treated with 0.5-3.0 M mineral acid with desorption of lanthanides. The amorphous sorbent used is one of the sorbents with the following composition: TiOHPO4·nH2O, (Ti1-xZrx)OHPO4·nH2O, TiONH4PO4·nH2O, (Ti1-xZrx)ONH4PO4·nH2O, where n≥1, x=0.05-0.5. |
 Method of producing complex oxide compounds of rare-earth metals / 2430884Production of complex oxide compounds of rare-earth metals involves preparation of a mixture from rare-earth metal oxide powder, metal powder and an oxygen-containing additive, taken in hyperstoichiometric ratio, putting the mixture onto a substrate and carrying out a combustion reaction. The oxygen-containing additive is perchlorate of an alkali or alkali-earth metal selected from sodium, potassium, lithium, barium, calcium or magnesium, which is first mixed with rare-earth metal oxide powder, with the following ratio of components in wt %: rare-earth metal oxide 65.71-88.06; metal 11.94-34.29; perchlorate of alkali or alkali-earth metal 13.49-24.71. |
 Method of cleaning fluorine-containing rare-earth concentrate / 2429199Concentrate obtained when processing apatite is treated with concentrated sulphuric acid in the presence of hydrated silica at 95-130°C with transition of fluorine to gaseous phase and obtaining a sulphate-phosphate rare-earth concentrate which is leached with water to obtain a sulphate rare-earth concentrate free from fluorine and phosphorus and a sulphate-phosphate solution. |
 Inorganic scintillation material, crystalline scintillator and radiation detector / 2426694Invention relates to novel inorganic scintillation materials, a novel crystalline scintillator, especially in form of a monocrystal, and can be used to detect ionising radiation in form of low-energy electromagnetic waves, gamma radiation, X-rays, cosmic rays and particles in fundamental physics, computerised tomography devices, PET tomographic scanners, new-generation tomographic scanners, gamma spectrometres, cargo scanners, well logging systems, radiation monitoring systems, etc. The halide-type scintillation material has the formula Ln(1-m-n)HfnCemA(3+n), where A is either Br, Cl or I or a mixture of at least two halogens from this group, Ln is an element selected from: La, Nd, Pm, Sm, Eu, Gd, Tb, Lu, Y; m is molar fraction of substitution of Ln with cerium, n is the molar fraction of substitution of Ln with hafnium, m and n is a number greater than 0 but less than 1, (m+n) is less than 1. The crystalline scintillator has formula Ln(1-m-n)CemA3:n-Hf4+, where Ln(1-m)CemA3 is the formula of the matrix of the material, A is Br, O or I or a mixture of at least two halogens from this group, Ln is an element selected from: La, Nd, Pm, Sm, Eu, Gd, Tb, Lu, Y; Hf4+ is a dopant, m is a number greater than 0 but less than or equal to 0.3, n is content of the Hf4+ dopant (mol %) which is preferably between 0.05 mol % and 1.5 mol %. The radiation detector has a scintillation element based on the novel inorganic scintillation material. |
 Method of extracting samarium and europium ions via ionic floatation using sodium dodecylsulphate / 2426599Invention can be used in chemical industry. Samarium and europium ions are extracted through ionic floatation with sodium dodecylsulphate, taken in ratio of 1:3 according to the stoichiometric equation Me3+ + 3C12H25OSO3 - = Me(C12H25OSO3)3, where Me is a samarium or europium cation, C12H25OSO3 is the dodecylsulphate ion. |
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Method of producing nanocrystalline powder of metal oxides / 2425803 Method involves production of metal hydroxides via reverse precipitation, drying and calcination. To prevent local change in pH of the solution of the precipitation agent, the reverse precipitation method involves ultrasonic treatment of the solution of metal salts in an atomising nozzle through which the said solution passes before reacting with the solution of the precipitation agent. The solution of metal salts undergoes ultrasonic treatment which enables to disperse the solution to droplets with size smaller than 1.0 mcm. |
FIELD: chemistry.
SUBSTANCE: composition contains 1-20% yttrium oxide, 1-30% tungsten oxide and zirconium oxide - the rest. The specific surface area of the composition is at least equal to 20 m2/g after calcination for 4 hours at 900°C.
EFFECT: high efficiency of the catalyst, obtaining catalysts with specific acidity and heat resistance.
13 cl, 1 tbl, 1 ex
The present invention relates to a composition based on zirconium oxide, yttrium oxide and tungsten oxide, to its preparation and its use as catalyst or catalyst substrate.
It is known that in order to be effective catalysts, as well as arrangements designed to serve them, the substrate should have a large specific surface area. In addition, always strive to be the catalysts that can be used at higher temperatures, and therefore, the catalyst, the stability of the specific surface of which is improved. This applies particularly to catalysts or substrates used for treatment of exhaust gases of automobile engines.
In addition, in an even more particular case, as processing gases of diesel engines by reduction of nitrogen oxides (NOx) ammonia or urea, there is a need for catalysts, with some acidity, but also a certain resistance.
Finally, some applications may require products that do not contain silicon, since it is known that in certain conditions, the silicon can react with precious metals, which are often used in catalysts, and worsen thus their characteristics.
Object of the invention is to provide materials that can be used to receive catalysts, to meet these needs.
This task is responsible composition according to the invention on the basis of zirconium oxide, yttrium oxide and tungsten oxide. These oxides are present in the composition in the following weight percentage:
- yttrium oxide 1%-20%;
- tungsten 1%-30%;
the rest is zirconium oxide.
Other characteristics, details and advantages of the invention will appear more fully in the study of the following description, as well as particular example, which is illustrative but not restrictive.
Hereinafter in the description under the specific surface area refers to the specific surface according to BET, determined by nitrogen adsorption in accordance with ASTM D 3663-78 established on the basis of the method of brunauer-Emmett-teller described in the journal "The Journal of the American Chemical Society, 60, 309 (1938)".
The annealing, after which the data on the surface is annealed in air.
Values of specific surface, which is specified for the given temperature and duration correspond, unless otherwise indicated, annealed in air at a constant temperature for a specified time.
The content given in mass per oxide, unless otherwise specified.
Check also that later in the description, unless otherwise specified, ranges of values are included boundary values.
The composition according to the of the invention differs, first, the nature of its components. As mentioned above, this composition is based on zirconium oxide and, in addition, it contains the oxides of yttrium and tungsten in proportions which have been given above.
The content of yttrium oxide can comprise, in particular, from 5% to 15%, and the content of tungsten oxide from 5% to 20%.
According to various compositions according to the invention can contain only the oxides of zirconium, yttrium and tungsten, but they can also contain, in addition, at least one oxide of rare earth element other than cerium. Here, under rare earth element refers to the elements of the group formed by elements of the periodic system with atomic numbers from 57 to 71 inclusive. This rare earth element can be, in particular, lanthanum, praseodymium, neodymium, and this element can also be present in combination.
In the case of the presence in the composition of rare earth element other than cerium, the number of yttrium and tungsten will be the same as above, but the amount of rare earth element can be from 1 to 10%, in particular from 2 to 7%, and the rest is zirconium oxide. The presence of a rare earth element in the composition is the result of stabilization of its specific surface area at high temperatures.
Another additional feature is risticii compositions according to the invention is their specific surface area. It can be at least 40 m2/g, in particular at least 60 m2/g and in particular at least 70 m2/g after calcination for 4 hours at 700°C. For these conditions, the annealing can be obtained from the surface, reaching at least to about 90-120 m2/g, and typically, the surface is greater than the lower tungsten content in the composition.
In addition, after a four-hour calcination at 900°C the surface may be at least 10 m2/g, in particular at least 20 m2/g and in particular at least 26 m2/g or at least 29 m2/year
Another interesting characteristic of the compositions according to the invention is their acidity. This acidity can be measured by the test conversion methylbutanol, which will be described further, and it is at least 90%, in particular it can be at least 95%. This acidity can also be estimated by acid activity, which is also measured on the basis of tests on conversion methylbutanol and which characterizes the acidity of the product, regardless of its surface.
This acid activity of at least 0.03 mmol/h/m2in particular, at least of 0.075 mmol/h/m2. It may also be, in particular at least 0.1 mmol/h/m2, in particular, at least 0.15 mmol/h/m2and these values are listed for the song, which was progulivali for 4 hours at 700°C.
The composition of the invention can be in the form of a mixture of crystallographic phases, in which the main phase is the phase of zirconium oxide crystallized in the tetragonal or cubic structure.
According to one private variant of implementation of the composition according to the invention can be in the form of a solid solution of the elements yttrium and tungsten in the zirconium oxide.
In this case, x-rays of these compositions reveal the existence of a single phase and the corresponding zirconium oxide crystallized in the tetragonal or cubic structure, reflecting thus the introduction of the elements yttrium and tungsten into the crystal lattice of the zirconium oxide and, consequently, to gain a true solid solution. Increased contents of yttrium generally favour the emergence of a cubic phase. This option is implementation - solid solution - fair for songs that were subjected to calcination for 4 hours at 700°C. This means that, after annealing under these conditions is not observed stratification of the mixture, i.e. the appearance of other phases.
The composition of the invention may also contain sulfate, which can be very low. This is the contents of the can is to be no more than 800 mln, in particular not more than 500 mln, also, in particular, not more than 100 mln, and the content is expressed in weight SO4by weight of the entire composition and measured by device type LECO or ELTRA, that is, the method using catalytic oxidation of the product in the induction furnace and infrared analysis formed SO2.
In addition, the composition of the invention may also contain chlorine at a very low concentration. This content can be no more than 500 mln, in particular not more than 200 mln, more precisely not more than 100 mln, in particular not more than 50 mlnd and, in particular, not more than 10 mlnd This content is expressed as mass of Cl relative to the weight of the entire composition.
Finally, the composition of the invention may also comprise alkali element, in particular a sodium content of not more than 500 mln, in particular not more than 200 mln, in particular not more than 100 mln, in particular not more than 50 mind This content expressed in mass of the element, for example the mass of Na, relative to the weight of the entire composition.
Chlorine and alkali measured by ion chromatography.
Next will be described a method of producing compositions according to the invention.
This method is characterized by that it comprises the following steps:
(a) a compound of zirconium, a compound of yttrium, possible connection of rare earth element other than cerium, and basic compounds is their lead into contact in a liquid medium, thereby precipitate;
- (b) may be specified precipitate was separated, washed and again enter into a slurry;
(c) in the medium obtained after step (a) or step (b), add the connection tungsten and acid to bring the pH of the formed medium to a value of 2 to 7;
(d) may precipitate obtained in the previous step, washed after separation of the precipitated environment;
(e) the precipitate obtained after step (c) or (d), calcined.
Above the various stages will now be described in more detail.
The first step of the method consists in connecting in a liquid medium zirconium compounds and compounds of yttrium. These compounds are present in the stoichiometric proportions required to obtain the desired final composition. In the case of obtaining a composition containing a rare earth element, according to the variant described above, in this first step is also the compound of the rare earth element.
Liquid medium further contains a basic compound.
Liquid medium is typically water.
The compounds are preferably soluble compounds. Compound of zirconium may be nitrate, which can be obtained, for example, the interaction of nitric acid with the hydroxide of zirconium. This may be a chloride or sulfate. According to one private Varian is the use of zirconium oxychloride.
As compounds of yttrium or rare earth element can be used inorganic or organic salts of these elements. You can mention the chloride or acetate, in particular nitrate.
As the primary connection, you can use products such as hydroxide or carbonate. Can be called alkaline or alkaline earth hydroxides and ammonia. You can also use a secondary, tertiary or Quaternary amines. You can also mention urea.
The specified stage (a) can be carried out in the presence of additives intended to facilitate its implementation, in particular to facilitate later handling of sludge. These additives can be selected from compounds of the type of sulfate, phosphate or polycarboxylate.
Under the connection sulfate type refers to all compounds containing the anion SO42-or able to give such an anion. This connection can be sulfuric acid, ammonium sulfate, alkali sulfate, in particular the sodium sulfate or potassium.
The integration of the various compounds can be carried out in any way. So, you can enter the connection yttrium together with the connection of zirconium in the reactor, containing at the bottom of the reactor vessel main connection and sulfate connection.
This first stage is usually carried out at room temperature (15-35°C).
At the output of stage (a) receive TV is RDY residue.
Then the method comprises a stage (b), in which the precipitate can be separated from its environment by any classical method of separation of the solid phase - liquid, such as filtration, decantation, dehydration or centrifugation. The product is subjected to one or more washings with water or aqueous solutions of acids or bases. After washing the precipitate is introduced into the suspension in the water and spend the next stage (c) of the method.
This step (c) is added to the environment, coming from the previous stage (stage (a) or (b)if it was performed), compounds of tungsten. This connection can be, in particular, inorganic salt, as metabolomic ammonium (NH4)6W12O41and metabolomic Na2WO4. In addition, add acid to bring the pH of the formed medium to a value of 2 to 7, in particular from 4 to 6. This acid may be an inorganic acid such as nitric acid.
Then the method includes the step (d), which is optional. This step is the separation of the precipitate obtained in the previous step, from its precipitating environment in the same way as described above for step (b), and then washing the obtained precipitate one or more times.
Note that according to one preferred variant implementation of the method comprises by at least one washing step (b) or (d), even more preferably, both of these stages, in particular, in the case when you want to obtain compositions with a low content of sulfate, chloride or alkali.
The last step of this method is the calcination of the precipitate obtained in step (c) or (d), and this annealing, possibly preceded by drying. This annealing can improve the crystallinity formed product, and it can also be adjusted depending on the temperature of the later application, for which it is intended composition, taking into account the fact that the specific surface of the product is lower the higher the temperature is held calcination. Such calcination is usually carried out in air.
In practice usually limited by temperature annealing in the range from 500°C to 900°C, in particular from 700°C to 900°C.
The duration of calcination may vary within wide limits, in principle it is greater, the lower the temperature. Solely as an example, the duration may vary from 2 hours to 10 hours.
The composition of the invention as described above or obtained by the method described above, are in the form of powders, but they can be molded to form granules, beads, cylinders, monoliths or filters in the form of honeycomb structures with varying sizes. These compositions can be applied to any item is Daiki, used usually in the field of catalysis, that is, in particular, on the substrate, thermally inert. These substrates can be selected from aluminum oxide, titanium oxide, cerium oxide, zirconium oxide, silicon oxide, spinels, zeolites, silicates, crystalline phosphates and silicates, crystalline aluminum phosphate.
The composition can also be used in catalytic systems. Thus, the invention relates to catalytic systems containing compositions according to the invention. These catalytic systems may include a coating (primer) with catalytic properties, based on these compositions, substrate type, for example, metal or ceramic monolith. The coating itself may also contain a substrate of the type mentioned above. This coating is obtained by mixing the composition with a base to form a suspension, which can then be applied to the substrate.
In the case of their use in catalytic systems, the composition of the invention can be used in combination with transition metals; thus, they play a role in substrate for these metals. Under the transition metals are the elements of groups IIIA-IIB of the periodic system. As transition metals include, in particular, vanadium and copper, and precious metals like platinum, rhodium, palladium, silver or ride. The nature of these metals and methods for their introduction in the composition of the substrate are well known to the specialist. For example, the metals can be introduced into the composition by impregnation.
The system according to the invention can be used in the processing gas. They can act as a catalyst for the oxidation of CO and hydrocarbons contained in these gases, or as a catalyst for reduction of nitrogen oxides (NOx) reduction reaction of these NOx by ammonia or urea, in this case as a catalyst for hydrolysis or decomposition of urea to ammonia (SCR process).
The gas, which is suitable for processing in the framework of the present invention is, for example, a gas emitted by stationary installations as gas turbines, boilers of thermal power plants. It can also be gases emanating from internal combustion engines, in particular diesel engine exhaust gases.
In the case of application in catalysis reactions for reduction of NOx by ammonia or urea, the composition of the invention can be used in combination with cerium or with metals of the type of transition metals, such as vanadium or copper.
Below is one example.
First, we describe the test conversion methylbutanol used to determine the pH of the compositions according to the invention.
This catalytic test described Pernot and others in Applied Catalysis, 1991, vol. 78, p. 213 and uses 2-methyl-3-butyn-2-ol (methylbutanol, or MBOH) as a molecular probe of the acidity-basicity of the surface of the obtained compositions. Depending on the acidity-basicity of the surface centers composition methylbutanol can participate in 3 of the following reactions:
| Table 1 |
| Reaction | The reaction product |
| Acid | 2-methyl-1-butene-3-in + 3-methyl-2-butenal |
| Amphoteric compound | 3-hydroxy-3-methyl-2-butanone + 3-methyl-3-butene-2-he |
| Base | Acetone + acetylene |
In the experiment the composition in an amount (m) of approximately 400 mg is placed in a quartz reactor. The composition is first subjected to a pretreatment at 400°C for 2 h in the gas stream N2when the throughput rate of 4 l/h
Then the temperature of the composition was adjusted to 180°C. After that, the composition is periodically brought into contact with a specified number MBOH. This periodic contact is to be made to circulate during the 4 minute injection of a synthetic mixture of 4 vol.% MBOH in N2at a flow rate of 4 l/h, which corresponds to a molar h is sec tor consumption methylbutanol (Q) 7.1 mmol/H. Spend 10 injection. At the end of each injection of the gas stream at the outlet of the reactor was analyzed by gas chromatography to determine the nature of the reaction products (cf. table 1) and their number.
The selectivity (S1of the product i in the reactions of methylbutanol is based on the percentage of this product from all of the formed products (where Cithere are a quantity of product i, and Σ means the sum of the products formed during the reaction). So, determine acidic, amphoteric or basic selectivity, which is equal to the sum of selectively formed products for the reactions, respectively acids, amphoteric compounds and bases. For example, acid selectivity (S[acid]) is equal to the sum of selectively 2-methyl-1-butene-3-inu and 3-methyl-2-butenal. So, the higher the acid selectivity, the greater the number of products formed by reaction of the acid and the greater the number of acid centers in the studied composition.
The degree of transformation of methylbutanol (TT) during the test is calculated by taking the average of the degrees of conversion of methylbutanol 5 last injection of test.
You can also define acid activity (A[acid]) compositions, expressed in mmol/h/m2on the basis of the degree of conversion of methylbutanol (TT, expressed in %), molar hour consumption METI is butanol (Q, expressed in mmol/h), acid selectivity (S[acid], expressed in %), number of analyzed composition (m, expressed in g) and specific surface composition (SBET, expressed in m2/g) according to the following equation:
A[acid]=10-4*TT*Q*S[acid]/(SBET*m)
Example
This example relates to the preparation of a composition based on oxides of zirconium, yttrium and tungsten in proportions, based on the weight of the oxide, 70%, 10% and 20%, respectively.
Prepare A solution by mixing in a beaker with stirring 219 g circinelloides (20 wt.% ZrO2), 18 g of sulfuric acid (97 wt.%) and 27 g of yttrium nitrate (391 g/l, Y2O3with 93 g permuteran water.
In the reactor mixture is injected 657 g of sodium hydroxide solution (10 wt.% NaOH) and 50 g permuteran water. Then, while stirring, gradually add the solution A. the pH of the medium was adjusted at least to 12.5, then adding the sodium hydroxide solution. The precipitate is filtered and washed at 60°C 3 liters permuteran water. The solid phase is introduced into the suspension and to complement 714 g permuteran water.
Prepare solution B by mixing 17.8 g of metavolume sodium dihydrate and 45 g permuteran water. Then, while stirring, gradually add in the suspension solution B. Then the pH set at 5.5 by addition of a solution of nitric acid (68%). The precipitate is again filtered and PR is myauth at 45°C 3 liters permuteran water.
The solid is dried overnight in a drying Cabinet at 120°C, then the resulting product is calcined in air for 4 hours at a constant temperature of 700°C. This product is characterized by a specific surface area of 68 m2/g and a pure tetragonal phase. After calcination in air for 4 hours at a constant temperature of 900°C specific surface area equal to 29 m2/year
The product contains 50 mlnd sodium, less than 10 mlnd chloride and less than 120 mln sulfates.
In the test conversion methylbutanol product, progulivavshimisya at 700°C/4 h, the acid has a selectivity of 97%and an acid activity 0,171 mmol/m2/PM
1. Composition based on zirconium oxide, yttrium oxide and tungsten oxide in the following mass proportions:
yttrium oxide is from 1% to 20%;
tungsten: from 1% to 30%;
the rest of the zirconium oxide,
characterized in that it has a specific surface area of at least 20 m2/g after calcination for 4 hours at 900°C.
2. The composition according to claim 1, characterized in that it has a content of yttrium oxide is from 5% to 15%.
3. The composition according to claim 1 or 2, characterized in that it has a content of the oxide of tungsten from 5% to 20%.
4. The composition according to claim 1 or 2, characterized in that it has a specific surface area of at least 40 m2/g after calcination for 4 hours at 700°C.
5. The composition according to claim 1 or 2, characterized in that is it has a specific surface area of at least 70 m 2/g after calcination for 4 hours at 700°C.
6. The composition according to claim 1 or 2, characterized in that it has an acidity as measured by test conversion methylbutanol, at least 90%.
7. The composition according to claim 1 or 2, characterized in that it further contains an oxide of rare earth element other than cerium, in a fraction comprising from 1 to 10%, in particular from 2 to 7%.
8. The method of obtaining the composition according to one of claims 1 to 7, characterized in that it comprises the following steps:
(a) bringing into contact zirconium compounds, compounds of yttrium, possible compounds of rare earth element other than cerium, and a basic compound in a liquid medium, resulting in a gain precipitate;
(b) may be specified precipitate was separated, washed and again enter into a slurry;
(C) in the medium obtained after step (a) or step (b), add the connection tungsten and acid to bring the pH of the formed medium to a value of 2 to 7;
(d) may precipitate obtained in the previous step, washed after separation of the precipitated environment;
(e) the precipitate obtained after step (C) or (d), calcined.
9. The method according to claim 8, characterized in that the compound of zirconium is the zirconium oxychloride.
10. The method according to claim 8 or 9, characterized in that step (a) is carried out in the presence of an additive selected from compounds of the type of sulfate, phosphate or polycarboxylate.
11. The catalytic system, characterized in that it contains a composition according to one of claims 1 to 7.
12. The method of processing gas, in particular of exhaust gases of a diesel engine, characterized in that as a catalyst for oxidation of CO and hydrocarbons contained in gases, use of the composition according to one of claims 1 to 7 or a catalytic system according to claim 11.
13. Method of treatment of exhaust gases of a diesel engine, characterized in that as a catalyst for reduction of nitrogen oxides (NOx) reduction reaction of these NOx by ammonia or urea use composition according to one of claims 1 to 7 or a catalytic system according to claim 11.