Catalyst and a method of conversion of ammonia

FIELD: chemical industry.

SUBSTANCE: the invention is pertinent to the field of chemical industry, in particular to production of a catalysts and processes of oxidation of ammonia in production of a weak nitric acid. The invention offers an ammonia conversion catalyst on the basis of the mixture of oxides of unitized structure and a method oxidation of ammonia in production of weak nitric acid. The catalyst represents a mixture of oxides of the over-all formula (AxByO3Z)k (MmOn)f, (NwPgvOv)r where: A - cation of Ca, Sr, Ba, Mg, Be, Ln or their mixtures; B - cations of Mn, Fe, Ni, Co, Cr, Cu, V, A1 or their mixtures; x=0-2, y=1-2, z=0.8-l.7; M - A1, Si, Zr, Cr, Ln, Mn, Fe, Co, Cu, V, Ca, Sr, Ba, Mg, Be or their mixtures; m=l-3, n=l-2; N - Ti, Al, Si, Zr, Ca, Mg, Ln, W, Mo or their mixtures, P - phosphorus, O - oxygen; w=0-2, g=0-2, v=l-3; k, f and r - mass %, at a ratio (k+f)/r=0-l, f/r=0-l, k/f = 0-100. The catalyst is intended for use in a composition of a two-stage catalytic system generated by different methods, also in a set with the trapping platinoid screens and-or inert nozzles. The technical result ensures activity, selectivity and stability of the catalyst to thermocycles at its use in two-stage catalytic system with a decreased loading of platinoid screens.

EFFECT: the invention ensures high activity, selectivity and stability of the catalyst to thermocycles at its use in two-stage catalytic system with a decreased loading of platinoid screens.

8 cl, 1 tbl, 5 ex

 

The invention relates to catalysts for the oxidation of ammonia in the production of weak nitric acid.

The main industrial catalysts for the oxidation of ammonia to the present time are mesh of platinum and its alloys with palladium and rhodium. In terms of the high cost of platinum group metals urgent task of reducing expenditures and losses of platinum. This task industry is solved by the process of oxidation in a two-stage catalytic system, in which the first stage using an incomplete set of platinum mesh, and the second - layer oxide catalyst.

There are various oxide catalysts for the oxidation of ammonia, in which the active component is iron oxide, chromium oxide, cobalt oxide, bismuth oxide, oxides with perovskite structure, exalent and other

Known oxide catalyst, a mixture of oxides of aluminum, iron, calcium and chromium, followed by pelletizing and calcining at 875-900° [SU # 641985, 1979].

A known catalyst for the oxidation of ammonia, containing, wt.%: 90-95 iron oxide and 5-10 chromium oxide, a mixture of nitrates of iron and chromium, keeping at 315° C, cooled, mixed with graphite, followed by pelletizing and calcining at 560-650° [FR No. 2119121 1972].

Known oxide catalyst produced in the form of tablets, consisting of iron oxide and aluminum oxide [SU # 1220193, 1986]. The method of preparation of the catalyst is a mixture of iron oxide and aluminum hydroxide in an acidic medium and subsequent termomaslyanym catalyst mass at 600-700°, grinding, pelletizing and sintering of the finished tablets. In the pilot test shows that it works on the second stage of the oxidation of ammonia.

The disadvantages of such catalysts should include significant gas-dynamic resistance of the layer of preformed catalyst, a change in the phase composition during operation, the presence of ammonia in the gas stream after the catalyst layer, the necessity of making special baskets for loading catalyst into the reactor, and the spillage of the catalyst in the process of its operation.

These shortcomings were eliminated after the development of a massive block of oxide catalysts on the basis of simple and complex oxides [RF 2117528, B 01 J 23/83, 20.08.1998; RF 2100068, B 01 J 23/78, 27.12.1997].

Known block catalyst for the oxidation of ammonia, which is a mixed oxide of General formula (AxInyAbout3z)k(MemAboutn)fwhere a is a cation of CA, Sr, Ba, Mg, Be, Ln, or a mixture thereof, In the cation Mn, Fe, Ni, Co, CR, cu, V or mixtures thereof, x=0-2, y=1-2, z=0,8-1,7, MemO n- aluminium oxide and/or silicon oxide, zirconium, chromium, aluminum silicates, oxides of rare earth elements (REE), or mixtures thereof, m=1-3, n=1-2, k and f - wt.%, when the ratio f/k=0,01-1 [US 6489264, 03.12.2002]. The catalyst was prepared by extrusion molding of the catalyst pastes through a specially designed die. The paste is prepared by mixing active in the oxidation of ammonia oxide powder (iron oxide or oxide with a perovskite structure with structural and " oven " components after injection of the electrolyte and other additives that provide the necessary rheological properties of pastes, sufficient mechanical strength and thermal stability of the blocks, as well as their resistance to thermal cycles. Massive block catalysts contain more than 50 wt.% active oxide and are in the shape of a square or hexagonal prisms with the width 45-80 mm, with channels of square or triangular cross-section and minimum wall thickness and size of the side channel 1.6 mm and 3.2 mm, respectively. The application of these catalysts in industrial units, UKL-7 as a second stage allows without reducing the output of nitrogen oxides to increase the mileage of the platinum mesh, 20-30% reduction in loading and loss of platinum, 2-3 times to reduce the aerodynamic resistance of the catalyst layer in comparison with the preformed oxide is utalization and therefore, the energy cost of the gas in the reactor. The process becomes more stable, no breakthrough of ammonia, which increases its safety [Chernyshev VI, brustein EA //Catalysis in industry. 2001, No. 3. P.30].

However, further reduction in the number of platinum mesh as the first stage, and the possibility of a two-stage process for the catalytic oxidation of ammonia in aggregates AK-72 is limited due to the inability to prepare the massive blocks with smaller channels and wall thickness (Pich), which would provide a higher geometric surface of the catalyst layer and, consequently, a higher degree of conversion of unreacted 1-stage ammonia, as the oxidation reaction proceeds in vneshnediffuzionnoe mode. These difficulties are due not only to the difficulty of forming such catalyst pastes, but also a decrease in strength and resistance to thermal cycles of a massive block of catalysts (blocks) with thin walls.

Known trick that can increase strength, thermal stability and stability of the catalysts to the cycles is the use of heat-resistant carriers, which are coated with the active ingredient. However, despite the popularity of this approach, industrial catalysts of this type the La process two-stage oxidation of ammonia does not exist. The main difficulties in the development of such catalysts is the interaction of the active component and the carrier, which reduces the activity and selectivity of the process, and the low strength of the coating of the active component, which is destroyed in the process of operation.

As a prototype of the selected catalyst for the oxidation of ammonia to oxides of nitrogen, comprising as the active component of the oxides of cobalt, iron, bismuth, chromium, manganese and mixtures thereof, which may have additive from the group comprising zinc, cerium, cadmium, and lithium, and a heat-resistant carrier monolithic structure. The material of the carrier is selected from the group comprising titanium dioxide, zirconium and silicon, oxides of aluminum, cerium, magnesium, alkaline earth metals, lanthanum, and mullite, kaolin clay, silicates and a thin foil of an alloy based on iron oxides. The active component in such a catalyst is 15-25 wt.%. The media has channels with a hydraulic diameter of 0.8-30 mm and volume of voids 60-85%. The method of preparation of such a catalyst is in the anointing of the active component of suspensions of salts [RF 2106908, B 01 J 23/78, 01 21/6, 20.03.98].

The disadvantage of this catalyst is sufficiently low, the outputs of nitrogen oxides, because, apparently, the low selectivity of the catalyst, probably due to the interaction of the active component and the carrier at the stage of preparation of the catalyst, and low durability of the coatings of the suspensions.

The problem to which the invention is directed, is to develop a solid oxidic bulk catalyst honeycomb structure for the oxidation of ammonia with high activity, selectivity and resistance to thermal cycles for use in two-stage catalytic system with a reduced loading of the platinum grids, including in aggregates AK-72.

The problem is solved using the reaction of the ammonia oxidation catalyst block structure representing the mixed oxides of the General formula (AxByO3z)k(MmOn)f, (NwPgOv)rwhere a is a cation of CA, Sr, Ba, Mg, Be, Ln, or a mixture thereof; the cations of Mn, Fe, Ni, Co, CR, cu, V, Al, or mixtures thereof; x=0-2, y=1-2, z=0,8-1,7; M Is Al, Si, Zr, Cr, Ln, Mn, Fe, Co, Cr, Cu, V, Ca, Sr, Ba, Mg, Be, or mixtures thereof; m=1-3, n=1-2; N - Ti, Al, Si, Zr, Ca, Mg, Ln, W, Mo, or mixtures thereof, P is phosphorus, O is oxygen; w=0-2, g=0-2, v=1-3; k, f and r - wt.%, when the ratio (k+f)/r=0-1, f/r=0-1, k/f=0-10000.

Mixed oxides comprising (AxInyAbout3z) can have a perovskite structure, hexaline, corundum, spinel, pyrochlore.

As an Ln, you can use the undivided industrial concentrates, such as, loparite concentrate cationic composition: La0.33Ce0.5Nd0.11Pr0.05Sm0.01or bastnasite concentrate cat the organizational structure: La 0.60Ce0.13Nd0.18Pr0.08Sm0.01or waste concentrate cationic composition of La0.32Ce0.19Nd0.23Pr0.09Ca0.017.

The zirconium oxide optionally contains an admixture of other cations, ensuring the stability of the tetragonal or cubic structure, such as metals 1, 2 and 3 groups.

The material corresponding to the composition of NwPgOvmay have a frame structure, and the structure of spinel, pyrochlore, perovskite, hexaline, corundum with a thermal expansion coefficient equal to 10-7-10-5To-1in the temperature range up to 900° C.

Block the catalyst may have a coefficient of thermal expansion in the range of 10-7-10-5K-1.

Block the catalyst may be in the form of a rectangular prism or inclined prism with an angle of inclination 0-45° . Changing the angle of the prism is achieved by changing the angle of slicing the molded blocks.

The task is also solved by a method of catalytic conversion of ammonia which comprises passing the reaction gas mixture containing ammonia and oxygen-containing gas through a two-stage catalytic system formed in various ways, including complete with catching the platinum mesh and/or inert nozzles in the second stage using block kata is isator cell structure, above.

(NwPgOv) is a formative component of the catalyst, which can be used, for example, titanium dioxide, titanium aluminate, aluminium silicates, framework phosphates with the structure of NASICON, cordierite, mullite, corundum, zirconium oxide modified with cations of alkaline earth or rare earth elements, and other thermally stable materials with low coefficients of thermal expansion (CTE~10-6).

(MmAboutn) is the " oven " part, which prevents the interaction of the active component and the carrier, which can be used oxides REE, Zr, Si, Al, Cr, Co, Mn, Fe, and mixtures thereof.

(AxByO3z) is the active component of the catalyst, which can be used for any active in the oxidation of ammonia simple and complex oxides.

However, the division is rather arbitrary, since the interaction between the components of the catalyst can not only lead to decreased activity, but also to increase. Active ingredient without interaction will not be held on the surface of the carrier block form, etc. that is why the catalyst is the totality of its constituent parts and cooking conditions, which determine in the end it often auditiv is s, operational properties.

The method of preparation of the catalyst comprises the following steps:

1. The preparation of a carrier.

In the mixer powders mixed powder of material with a low CTE with compounds that give the annealing oxides of Al, Cr, Si, Zr, REE or aluminosilicates in an acidic environment. To improve the resistance to thermal cycles at the stage of mixing the paste composition may be optionally entered reinforcing aluminosilicate fiber. As Al-containing bonding agent used: basic salts of aluminum, hydroxides of aluminum or maloperation oxides of aluminum, CR-containing - chromic acid; Si-containing kaolin; Zr-containing basic salts of zirconium; Ln-containing - lanthanide nitrates. To improve the rheological characteristics of the paste composition to add surface-active substances - glycol, polyethylene oxide, carboxymethyl cellulose, polyvinyl alcohol, glycerin, etc. Of the obtained paste is formed by extrusion blocks cell structure. The media is dried at finite temperature - 120° C, then calcined in air at 700-1300° 2-24 hours

2. To reduce the interaction between the active component and the carrier, as well as to increase the strength of adhesion of the active component and the carrier on the surface of the block carrier is applied thermostability component of the catalyst is Ecodom impregnation of the viscous polymer salt compositions. "Oven " component to form a dense oxide film, located mainly on the geometric surface forming component, is formed after heat treatment, the polymer coating. As the " oven " component choose composition without impairing the catalytic properties of the active component. In some cases the role of the " oven " of a component can perform mixed oxide, which is formed of a catalytically active composition after direct deposition on the forming component of the catalyst and heat treatment.

3. The active component of the catalyst is also applied by impregnation of the polymeric salt compositions of the composite obtained in stage 2, with subsequent stages of treatment.

The invention is illustrated by the following examples of the preparation of the catalysts and the results of their tests in the oxidation of ammonia, are given in tables.

Chemical analysis of the catalysts is carried out by flame photometry, phase - x-ray methods, specific surface area determined by BET method, the catalytic activity in the oxidation of ammonia for fragments of the blocks is determined at temperatures of 700-900° installing flow type. The main part of the installation is a quartz reactor with a diameter of 2 cm, sleep is defined devices to accommodate oxide catalyst in the form of a fragment of the block and sampling points. The degree of conversion of ammonia and selectivity for nitrogen oxides is determined by spyektrofotomyetrirovaniya gas mixture. To control determines the selectivity of oxidation on one of the platinum grid, which is 83-86%, which coincides with the data of chemical analysis. The initial mixture contains 5% of the ammonia feed rate of the mixture of 0.3 m/s, the height of the fragments of 25-50 mm, the contact time 0.16 C. Vary the temperature of the test - T,° C.

Below in the examples described compositions of the catalysts and methods for their preparation, including the preparation of the formative component of the catalyst NwPgOv(1.1-5.1), the application of the " oven " part of the catalyst MmOn(1.2.1-1.2.5; 2.2.1-2.2.3) and the application of the active component of the catalyst AndxInyAbout3z(1.3.1.-1.3.9; 2.3.1.-2.3.4; 3.2.1.-3.2.4; 4.2.1; 5.2.1.).

Example 1. Preparation of catalysts, where NwPgOvhas a frame structure.

1.1. The preparation of a carrier (formative component of the catalyst).

Cordierite blocks prepared by extrusion molding through a specially designed die paste formed by mixing clay, talc and amorphous alumina, taken in the stoichiometric ratio and the previously subjected to machining vibration in a centrifugal ball mill VCM-25 or d is integratore DAISY, electrolyte and surfactant. The blocks are moulded in the shape of a prism with square section 75× 75× 25 mm and calcined at 1164° C for 4 h Chemical composition of the medium corresponds to the formula 2MgO2Al2O35SiO2. For the preparation of catalysts cut out pieces of blocks with a diameter of 2 cm with the following kharakterstikami:

Sbeats- 0.7 m2/g;

Vthen=0.119 cm3/g;

Block height - 25 mm;

Wall thickness - 0.6 mm;

Pipe size - 3.5× 3.5 mm;

The geometric surface of the block 56 cm2;

KTR 2· 10-6deg-1.

1.2. Application of the substrate ("oven " component of the catalyst).

1.2.1. To 30 g of mischmetall (Ln2About3slowly add 40 ml conc. nitric acid, the solution is heated on a water bath under stirring until complete dissolution of mischmetall. Blocks in section 1.1. dip into the warm solution and leave for 3 minutes, then rinsed. After wilting in air for 24 h, the blocks are dried at 160-300° and calcined at 700° C-900° Forming oxide La0.33CE0.5Nd0.11Pr0.05Sm0.01has a pyrochlore structure.

1.2.2. In 25 ml of distilled water dissolve 12.5 g of lanthanum nitrate 6 water, add 11.66 g of iron nitrate 9-water, 4 ml of citric acid solution (2 g/ml) and 2.5 ml of ethylene glycol. The solution is heated on a water bath Ave is stirring. Next, as in 1.2.1. Formed LaFeO3has a perovskite structure.

1.2.3. In 25 ml of distilled water dissolve 12.5 g of lanthanum nitrate 6 water, add 8.33 g of manganese nitrate 6-water, 4 ml of citric acid solution (2 g/ml) and 1.5 ml of ethylene glycol. The solution is heated on a water bath under stirring. Next, as in 1.2.1. Formed Ln3has a perovskite structure.

1.2.4. To 30 g of mischmetall (Ln2About3slowly add 40 ml conc. nitric acid, the solution is heated on a water bath under stirring until complete dissolution of mischmetall. Blocks in section 1.1. dip into the warm solution and leave for 3 minutes, then rinsed. After wilting in air for 24 h, the blocks are dried at 160-300° and calcined at 700° C-900° C. the Formed oxide formula meets the composition of La0.60Ce0.13Nd0.18Pr0.08Sm0.01.

1.2.5. To 30 g of mischmetall (Ln2About3slowly add 40 ml conc. nitric acid, the solution is heated on a water bath under stirring until complete dissolution of mischmetall. Blocks in section 1.1. dip into the warm solution and leave for 3 minutes, then rinsed. After wilting in air for 24 h, the blocks are dried at 160-300° and calcined at 700° C-900° C. the Formed oxide formula meets the composition of La0.32Ce0.19Nd0.23Pr0.09Ca.017 .

1.3. The application of active catalyst component.

1.3.1. In the solution according to paragraph 1.2.2. immersing the sample in 1.2.1. Next, as in 1.2.1. The composition of the catalyst corresponds to the formula

(LaFeO3)0.02(La0.33Ce0.5Nd0.11Pr0.05Sm0.01)0.04(2MgO2Al2O35SiO2)0.94. KTP catalyst 2· 10-6deg-1.

1.3.2. In the solution according to paragraph 1.2.2. immersing the sample in paragraph 1.2.2. Next, as in 1.2.1. The composition of the catalyst corresponds to the formula (LF3)0.04(2MgO2l2O35SiO2)0.96. KTP catalyst 5· 10-6deg-1

1.3.3. In the solution according p. immersing the sample in 1.2.1. Next, as in 1.2.1. The composition of the catalyst corresponds to the formula (LaMnO3)0.02(La0.33Ce0.5Nd0.11Pr0.05Sm0.01)0.04(2MgO2Al2O35SiO2)0.96. KTP catalyst 7· 10-6deg-1.

1.3.4. In the solution according p. immersing the sample in 1.2.2. Next, as in 1.2.1. (LaMnO3)0.04(2MgO2Al2O35SiO2)0.96. KTP catalyst 5.1· 10-6deg-1.

1.3.5. In 25 ml of distilled water dissolve 65.75 g of cobalt nitrate 6-water, add 4 ml of citric acid (2 ml/g) and 1.5 ml of EG. In the solution, immersing the sample in p. Further p. The resulting cobalt oxide Co3O4has a spinel structure. The composition of the catalyst corresponds to the formula (Co3O4)0.03(La0.33 Ce0.5Nd0.11Pr0.05Sm0.01)0.04(2MgO2Al2O35SiO2)0.93. KTP catalyst 6· 10-6deg-1

1.3.6. In 25 ml of distilled water dissolve 51 g of iron nitrate 9-water, add 4 ml of citric acid (2 ml/g) and 1.5 ml of EG. Further p. The resulting iron oxide has a structure of corundum. The composition of the catalyst corresponds to the formula (Fe2O3)0.03(La0.33CE0.5Nd0.11Pr0.05Sm0.01)0.04(2MgO2Al2O35SiO2)0.93. KTP catalyst 5· 10-6deg-1.

1.3.7. In 25 ml of distilled water dissolve the 106.5 g of manganese nitrate 6-water, add 4 ml of citric acid (2 ml/g) and 1.5 ml of EG. Next, as in p. The resulting manganese oxide has a spinel structure. The composition of the catalyst corresponds to the formula (MnO2)0.05(La0.33Ce0.5Nd0.11Pr0.05Sm0.01)0.04(2MgO2Al2O35SiO2)0.91. KTP catalyst 5· 10-6deg-1.

1.3.8. Analogously to example 1.3.7. The carrier has the form of an inclined prism with an angle of 45° C.

1.3.9. In 25 ml of distilled water dissolve the 106.5 g of manganese nitrate 6-water, add 4 ml of citric acid (2 ml/g) and 1.5 ml of EG. Next, as in p. The resulting manganese oxide has a spinel structure. The composition of the catalyst corresponds to the formula (MnO2)0.05(La0.60 Ce0.13Nd0.18Pr0.08Sm0.01)0.04(2MgO2Al2O35SiO2)0.91. KTP catalyst 5· 10-6deg-1.

Example 2. Preparation of catalysts, where NwPgOvhas the corundum structure.

2.1. The preparation of a carrier (formative component of the catalyst).

Corundum blocks prepared by extrusion molding (through a specially designed die) paste formed by mixing powder of corundum (being not less than 70%) and a binder consisting of a mixture of amorphous aluminum oxide, pseudoboehmite and bayerite, acidic electrolyte and surfactant. The blocks are moulded in the shape of a prism of square cross section 70× 70× 25 mm and calcined at 1200° C for 4 h characteristics of prepared medium:

Sbeats4 m2/g;

Vthen=0.64 cm3/g;

Block height - 25 mm;

Wall thickness - 0.6 mm;

Pipe size - 3.5× 3.5 mm;

The geometric surface of the block 56 cm2;

KTR 8· 10-6deg-1.

2.2. Application of the substrate ("oven " component of the catalyst).

2.2.1. In the solution according p. immersing the blocks in section 2.1. Next, as in p. the resulting oxide film has a composition of La0,33Ce0,5Nd0,11Pr0.05Sm0.01.

2.2.2. In the solution according to paragraph 1.2.2. immersing the blocks in section 2.1. Next, as in p. Brazauskas the oxide film has a composition LF 3.

2.2.3. In the solution according p. immersing the blocks in section 2.1. Next, as in p. The resulting oxide film has a composition LaMnO3.

2.3. The application of active catalyst component.

2.3.1. In the solution according to paragraph 1.2.2. immersing the sample in 2.2.1. Next, as in 1.2.1. The composition of the catalyst corresponds to the formula (LaFeO3)0.1(La0.33Ce0.5Nd0.11Pr0.05Sm0.01)0.17(Al2O3)0.73. KTP catalyst 9· 10-6deg-1.

2.3.2. In the solution according to paragraph 1.2.2. immersing the sample in p. Next, as in 1.2.1. The composition of the catalyst corresponds to the formula (LF3)0.3(A2O3)0.7. KTR catalyst 9· 10-6deg-1

2.3.3. In the solution according p. immersing the sample in 2.2.1. Next, as in 1.2.1. The composition of the catalyst corresponds to the formula (Co3O4)0.13(La0.33Ce0.5Nd0.11Pr0.05Sm0.01)0.17(Al2O3)0.07. KTR catalyst 10· 10-6deg-1.

2.3.4. In the solution according p. immersing the sample in 2.2.3. Next, as in 1.2.1. The resulting oxide has a structure of exhalent after calcination at 1200° C.

Example 3. Preparation of catalysts, where NwPgOvhas a pyrochlore structure.

3.1. The preparation of a carrier (formative component of the catalyst).

Blocks of zirconium oxide is prepared by extrusion molding (via Acelino designed Spinneret) pasta, formed by mixing powder of zirconium dioxide (being not less than 70 wt.%) and a binder consisting of a mixture of amorphous aluminum oxide and pseudoboehmite, acidic electrolyte and surfactant. The blocks are moulded in the shape of a prism of square cross section 70× 70× 25 mm and calcined at 1200° C for 4 h Formula composition of the carrier is responsible ZrO20.5l2O3. Characteristics of prepared medium:

Sbeats4 m2/g;

Vthen=0.64 cm3/g;

Block height - 25 mm;

Wall thickness - 0.6 mm;

Pipe size - 3.5× 3.5 mm;

The geometric surface of the block 56 cm2.

3.2. The application of active catalyst component.

3.2.1. In the solution according to paragraph 1.2.2. immersing the sample in section 3.1. Next, as in 1.2.1. The resulting oxide film has a composition LFO3·KTR catalyst 5· 10-6deg-1.

3.2.2. In the solution according p. immersing the sample in section 3.1. Next, as in 1.2.1. The resulting oxide film has a composition LaMnO3. KTP catalyst 4· 10-6deg-1.

3.2.3. In the solution according p. immersing the sample in section 3.1. Next, as in 1.2.1. The resulting oxide is responsible formula composition of Co3O4. KTP catalyst 7· 10-6deg-1.

3.2.4. In the solution according p. immersing the sample in p. Next, as in 1.2.1. KTP catalyst 7· 10-6deg-1.

The resulting ACS is d Ln 3has a perovskite structure.

Example 4. Preparation of catalysts, where NwPgOvhas a frame structure NZP materials.

4.1. The preparation of a carrier (formative component of the catalyst). In the mixer powders mixed powders frame transition metal phosphate - Ca0.5Mg0.5Zr4P6O24(NZP) and aluminum hydroxide in an acidic medium before the formation of the plastic paste, which is formed by extrusion in the form of blocks of cellular structure. After drying, the blocks calcined at 1100° C.

Characteristics of prepared medium:

Sbeats- 4.5 m2/g;

Vthen- 0.50 cm3/g;

Block height - 25 mm;

Wall thickness - 0.6 mm;

Pipe size - 3.5× 3.5 mm;

The geometric surface of the block 56 cm2.

4.2. The application of active component.

4.2.1. In the solution according p. immersing the sample in clause 4.1. Next, as in 1.2.1. The formed oxide film has a composition Ln3. KTP catalyst 8· 10-7deg-1.

Example 5. Preparation of catalysts, where NwPgOvhas a frame structure NZP materials.

5.1. The preparation of a carrier (formative component of the catalyst). In the mixer powders mixed powder frame transition metal phosphate - NaZrCrP3O12with the gel of the same composition to education the project for a plastic paste, which is formed by extrusion in the form of blocks of cellular structure. The blocks are dried and calcined at 1000° C.

5.2. The application of active component.

5.2.1. In 25 ml of distilled water dissolve 12.5 g of lanthanum nitrate 6 water, add 8.33 g of cobalt nitrate 6-water, 4 ml of citric acid solution (2 g/ml) and 1.5 ml of ethylene glycol. The solution is heated on a water bath under stirring. Next, as in 1.2.1. Formed L3has a perovskite structure. KTR catalyst 5· 10-7deg-1.

Table 1 provides data on the composition of certain catalysts and data on catalytic activity (the degree of conversion and selectivity for nitrogen oxides)obtained on fragments of microblocks. The contents of the " oven " components of ~4 wt.%, the content of the active oxide, input 1 impregnation ~2 wt.%. As shown, the " oven " component of the catalyst has a low degree of conversion and selectivity for nitrogen oxides. The introduction of the active component in the catalyst composition and the increase in the test temperature increases the degree of conversion of ammonia to almost 100% for all oxide systems. However, the selectivity of the reaction of nitrogen oxides with increasing temperature is reduced, and most significantly for simple oxides. High selectivity is of utilizatorul persists to high temperatures for the catalysts based on complex oxides with " oven " component. Thus it is seen that the chemical composition of the catalyst has a significant impact on the activity and selectivity of the oxidation process. The application of active component without the stabilizing component actually leads to a decrease in the selectivity of the process, apparently due to the interaction between the structure and the active components of the catalyst.

The highest activity and selectivity over a wide temperature region showed cobaltic and lanthanum manganite. With increase in the content of perovskite selectivity increases. The samples stand at least 20 cycles of heating and cooling to 700° in the air without the formation of cracks and peeling of coating components.

Check the stability of the catalysts for continuous operation in industrial conditions within three months shows that the catalyst maintains high activity, selectivity and durability.

The proposed catalysts can find wide application in the industrial production of nitric acid by oxidation of ammonia in part two (platinum mesh + oxide catalyst) catalytic system formed in various ways, including complete with catching the platinum mesh and/or inert nozzles.

1. The catalyst for the conversion of ammonia into nitric oxide (II) - based mixed oxide block of honeycomb structure, characterized in that it is a mixed oxide of General formula (AxByO3z)k(MmOn)f, (NwPgOv)rwhere a is a cation of CA, Sr, Ba, Mg, Be, Ln, or a mixture thereof; the cations of Mn, Fe, Ni, Co, CR, cu, V, Al, or mixtures thereof; x=0-2, y=1-2, z=0.8 to l-7; M is Al, Si, Zr, Cr, Ln, Mn, Fe, Co, Cu, V, Ca, Sr, Ba, Mg, Be, or mixtures thereof; m=1-3, n=1-2; N-Ti, Al, Si, Zr, Ca, Mg, Ln, W, Mo, or mixtures thereof, P is phosphorus, O is oxygen; w=0-2, g=0-2, v=1-3; k, f and r - wt.%, when the ratio (k+f)/r=0-1, f/r=0-1, k/f=0-10000.

2. The catalyst according to claim 1, characterized in that the mixed oxides in the composition (AxInyAbout3zhave a perovskite structure, hexaline, corundum, spinel, pyrochlore.

3. The catalyst according to any one of claims 1 and 2, characterized in that the mixture of lanthanide - Ln may have a stoichiometric composition of cations, the corresponding industrial undivided concentrates, for example loparite concentrate composition of La0.33Ce0.5Nd0.11Pr0.05Sm0.01or bastnasite concentrate La0.60Ce0.13Nd0.18Pr0.08Sm0.01or waste concentrate La0.32Ce0.19Nd0.23Pr0.09Ca0.17.

4. Catalyst according to any one of claims 1 to 3, characterized in that the oxide CID is one, used in MmAboutn, further comprises the admixture of other cations, ensuring the stability of the tetragonal or cubic structure, such as metals 1, 2 and 3 groups.

5. Catalyst according to any one of claims 1 to 4, characterized in that the material meets the composition of NwPgOvhas either a frame structure or a spinel structure, or pyrochlore or perovskite, or exhalent or corundum with a thermal expansion coefficient equal to 10-7-10-5To-1in the temperature range up to 900°C.

6. Catalyst according to any one of claims 1 to 5, characterized in that it has a coefficient of thermal expansion in the range of 10-7-10-5To-1.

7. Catalyst according to any one of claims 1 to 6, characterized in that it has the shape of a rectangular prism or inclined prism with an angle of inclination 0-45°.

8. Method of catalytic conversion of ammonia, comprising passing the reaction gas mixture containing ammonia and oxygen-containing gas through a two-stage catalytic system formed in various ways, including complete with catching the platinum mesh and/or inert nozzles, characterized in that the second step using the catalyst according to any one of claims 1 to 7.



 

Same patents:

FIELD: chemical industry; production of nitric acid.

SUBSTANCE: the invention is dealt with production of nitric acid with the help of oxidation of ammonia by oxygen of the air and absorption of nitrogen oxides by water in installations with uniform pressure at the stages of oxidation of ammonia and absorption of nitrogen oxides. The method of production of nitric acid in the installations with uniform pressure at the stages of oxidation of ammonia and absorption of nitrogen oxides provides, that compression of the air up to a uniform terminal pressure is conducted continuously within one stage without intermediate cooling and after that the compressed and so heated air is divided into two streams, one of which intended for production of nitric acid is directed to be cooled with further mixing with ammonia, and another is fed directly into a fuel combustion chamber connected with a recuperation turbine. The design embodiment of the installation for production of nitric acid provides for usage in the gas-turbine plant as an air engine for compression of air of an axial-flow compressor mounted directly on a common shaft with the recuperation turbine, at which near the outlet of the air engine the line of a compressed air stream is divided into two parts, one of which intended for production of nitric acid is first connected with a compressed air cooler and then with a mixer of ammonia with air, and the second intended for incineration of fuel is directly connected with the recuperation turbine combustion chamber. Besides in the capacity of a the compressed air cooler they use a "boiling" economizer connected to a line of a feed water for a boiler-utilizer and with a vapor collector of the boiler-utilizer by a line of steam-and-water mixture. The line of the air intended for production of nitric acid is also connected through the reheater of ammonia with a nitric acid blowing column. The technical result is simplification of the method, decreased investments and specific consumption of fuel.

EFFECT: the invention ensures simplification of the method, decreased investments and specific consumption of fuel.

4 cl, 1 dwg

The invention relates to a device and method of removal of N2About during the manufacture of nitric acid

The invention relates to a catalyst and process for the oxidation of ammonia in the production of weak nitric acid

The invention relates to the production of nitrous oxide by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to processes of high-temperature catalytic conversion of ammonia in a two-stage catalytic system in the production of nitric acid

The invention relates to a method of heat recovery nitrous and tail gas emissions in installations for the production of nitric acid

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to a method for preparing CdS photocatalyst for hydrogen production and to a method of obtaining hydrogen from water by photochemical reaction with its application
The invention relates to an improved method for the oxidation of cyclic hydrocarbons, alcohols and/or ketones to carboxylic acids with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

The invention relates to catalysts and methods of producing nitrous oxide (N2O) by oxidation of ammonia with oxygen or oxygen-containing gas

FIELD: alternative fuel production and catalysts.

SUBSTANCE: invention relates to (i) generation of synthesis gas useful in large-scale chemical processes via catalytic conversion of hydrocarbons in presence of oxygen-containing components and to (ii) catalysts used in this process. Catalyst represents composite including mixed oxide, simple oxide, transition element and/or precious element, carrier composed of alumina-based ceramic matrix, and a material consisting of coarse particles or aggregates of particles dispersed throughout the matrix. Catalyst has system of parallel and/or crossing channels. Catalyst preparation method and synthesis gas generation method utilizing indicated catalyst are as well described.

EFFECT: enabled preparation of cellular-structure catalyst with high specific surface area, which is effective at small contact times in reaction of selective catalytic oxidation of hydrocarbons.

6 cl, 2 tbl, 16 ex

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