The preparation method of catalyst for deep oxidation of hydrocarbons and carbon monoxide

 

(57) Abstract:

Preparation of a catalyst based on a metal tube or rod for deep oxidation of hydrocarbons and carbon oxide deposited on the tube surface of the catalyst layer includes a mixture of insoluble or low-solubility compounds with powdered aluminum, with subsequent backfilling material in a molding device with a metal tube or rod, and after the steam treatment of the formed product is removed from the molding device, dried and calcined, with the catalytic layer is a thick, highly porous, samozakravatayasa coating when the coating thickness (mm): 0,6 = 10,0. Increases the activity unit of geometric surface of the catalytic element on the metal carrier, its stability, and decreases the intensity and simplifies the preparation of the catalyst. 7 C.p. f-crystals, 1 table.

The invention relates to the field of technical chemistry, namely, catalysts (catalytic elements) for deep oxidation of carbon monoxide, hydrocarbons and other substances by burning fuel, the oxidation of harmful pollutants in the exhaust gas fluids.

It is known that to reduce the hydraulic resistance requires regular device layer of the catalyst placed in the reactor or turbine. Such a device layer can be achieved by using a catalyst carrier in the form of honeycomb structures, tubes, rods, plates, foam materials, etc., deposited on the surface of the carrier of the active component [U.S. patent N 3794588, class B 01 J 11/06, 1974; U.S. patent N 4410454, class B 01 J 23/10, 1983; U.S. patent N 2720494, CL 252-471, 1955]. For catalysts based on porous media, which are usually above-mentioned materials, the most important characteristics are the thickness of the active layer and the concentration of components per unit surface area of the media.

Thus, a known catalyst active component in a layer thickness from a monomolecular to 0,0254 mm (10 "mills") [U.S. patent N 3794588, class B 01 J 11/06, 1974] containing transition elements 4-6 periods of the Periodic table, including platinum metals; alkaline-earth and rare-earth elements deposited on the microscopically smooth media. Also known catalyst with deposited thickness of the active layer is not more than 0.1 mm [US patent N 4410454, class B 01 J 23/10, 1983], containing platinum group metals and rare earth Elia active component in wt. % is not unequivocal in his response, because the same amount of active ingredient per unit geometric surface malabarista or non-porous media thickness of the carrier can vary significantly. The activity per unit of surface of the carrier will be the same in contrast to the activity per unit weight of catalyst.

Also known catalyst with deposited thickness of the active layer is about 0.5 mm, containing a platinum metal deposited on the metal [U.S. patent N 2720494, CL 252-470, 1955]. [Ed.St. USSR N 910180, class B 01 J 23/74, B. I. N 9, 1982] describes a catalyst containing up to 20 wt.% Co3O4printed on metallic titanium with a specific surface area of 0.04 m2/g (or 0,00046 g Co on 1 cm2titanium). In General, for all of the above catalysts is characterized by low porosity, low concentration of active ingredient applied per unit surface area is non-porous or malabarista metal carrier, and, therefore, not very high activity unit of geometric surface of the media.

To improve the efficiency of the catalyst, on the surface of the metal carrier put a highly porous ceramic SL is/02; B. I. N 41, 1979]. The thickness of the most highly porous coatings (s) does not exceed 100 μm [U.S. patent N 4771029, class B 01 J 24/04, 1988]. Thus, a highly porous coating, described above, is not thick. Small thickness of the coating causes their low absorption capacity (capacity per unit geometric surface non-porous metallic base. This leads to the fact that the number entered in highly porous layer of the active component is small, so basically as the active component of such catalysts use platinum metals. In addition, the small thickness of the highly porous layer of catalyst reduces its thermal stability, resistance to poisons, the influence of the reaction medium, reduces the life of the catalyst [U.S. patent N 4771029, class B 01 J 24/04, 1988].

The above-mentioned disadvantages of media systems-predecessors) because of the inadequacy of the methods of their preparation. One of the main ways to obtain a highly porous coating on the porous base is impregnated porous framework in the suspension containing highly porous substance or its precursor, followed by drying and calcination. Thus, in [ed. St. USSR N 6956597, class B 01 J 37/02, B. I. N 41, 1979] ISPO J 24/04, 1988] describes a suspension containing fine powder milled in the wet state of the aluminum oxide, the promoter and the noble metal, which is non-porous monolith is immersed, followed by drying and calcination. The disadvantage of this method of cooking is too low concentration of the applied substances in suspension, since the greater the concentration of the slurry becomes too viscous. In the result, the thickness of the highly porous layer, as noted above, is insufficient.

To obtain a thick highly porous coatings on the basis of non-porous uses a variety of additional reinforcing elements. [US patent N 4019969, CL C 25 D 5/50, 1977] on the metal tube electrochemically pre-inflicted spongy metal, and then impregnated in the salt solution followed by heat treatment received highly porous coating thickness of 0.5 to 0.6 mm in the composition of the catalytic layer includes a Nickel covered "neustanovivshiesya" ceramic oxide type Al2O3and "recovering" oxide-type NiO. The specific surface of the porous catalytic layer is 10-15 m2/year of the Disadvantages of this invention are relatively the Kie coverage, having a specific surface area of less than 20 m2/g belong to malabaricum materials.

There are also known methods of preparation of the catalytic elements, in which the catalytic layer in the form of fabric attached to the outer side of the tube using malabarista reinforced material (metal mesh, wire or rings) (Japan patent N 57-16656, class B 01 D 53/39; Japan patent N 57-16655, class B 01 D 53/56; Japan patent N 57-16927, class D 01 D 53/56]. The main disadvantage of all these methods of obtaining highly porous, thick-film coatings is that they include an additional stage, increasing the time and intensity of the resulting product.

[RF patent N 2059427, class B 01 J 23/75, B. I. N 13, 1996], selected as a prototype, described is a method of obtaining highly porous catalytic material for deep oxidation of hydrocarbons and CO, including the use of low-soluble or water-insoluble compounds, which are mixed with powdered aluminum and sticking of the mixture in the molding device and the steaming water. These materials can be used as a highly porous thick coatings on metal tubes, however, in the prototype are not described spanioli unit geometric surface of the catalytic element on a metal carrier (tube), its thermostability, on the one hand, and the reduction of metal consumption, simplification of its preparation.

The problem is solved by placing the material in a molding device together with the powder components is a metal tube, extracting the resulting product after steam treatment, drying and calcination. This metal tube is formed thick, highly porous, samozakravatayasa, catalytic coating thickness of 0.6-10.0 mm; the concentration of platinum group metals (Me) per unit geometric surface non-porous or malabarista media to 0,120 g/cm2; transition elements (M) - up to 2.40 g/cm2; rare-earth elements (R) - to 1,91 g/cm2; alkaline earth elements (A) to 1.52 g/cm2. As the main binder in the present invention are compounds based on aluminum, so in all variants highly porous, composite layer includes aluminum in the amount of 0.02-3,22 g/cm2.

As a metal carrier in the proposed catalytic element can be used metals or their alloys, made in the form of tubes or rods with a low specific surface area. Highly porous layer can be heat by passing a cold fluid or gas. Highly porous catalytic layer can be applied and with the two sides of the metal tube to increase the activity per unit volume of the catalytic reactor or turbine. For rods catalytic layer is applied only on the outer surface. All the elements of a highly porous catalytic layer can be distributed evenly and unevenly distributed in the layer, to form a variety of individual and mixed compounds in various combinations with each other. Highly porous layer can be single-phase or multiphase composition. Oxide or metal oxide compounds that comprise a highly porous layer may include body-centered, face-centered and other structures of metals or their alloys; structure of spinel, corundum, double oxides, rutile, perovskite, pyrochlore, and others, as well as solid solutions on the basis of these oxides. Depending on the composition and method of preparation pore volume and size distribution can vary within wide limits.

The term "highly porous" in accordance with [U.S. patent N 4046712, class B 01 J 23/56, 1977], refers to coating with a specific surface area of more than 20 m2/g per unit weight of the coating. The term "thick" potatoe to exist in the form of a mechanically stable composite (granules, rings and so on) and without metal, including tubular, the basics. Therefore, the catalytic elements based on metal tubes with samonasraivayuschiesya ceramic or cermet coatings do not require as additional design details special reinforcing details unlike other catalytic elements with thick coatings.

The term "rare earth elements" is used in a broad sense, as implying 4f elements and side elements IIIb group of the Periodic table (La, Y). The term "transition elements" refers to 3d elements 4 period of the Periodic table. The term "platinum group metals" refers to the transition metals 5 and 6 periods of the family of platinum in the Periodic table.

The preparation of the catalyst (catalyst element) based on a metal tube for deep oxidation of hydrocarbons and carbon monoxide comprises the following stages:

a) preparing a mixture by mixing a powder of aluminum with other powdery, fixed, metal oxide or other components;

b) placing the mixture and a metal tube in a forming device;

C) processing f the STI non-porous frameworks;

g) removing the resulting product from the molding device, its drying and calcination with the formation of highly porous coatings;

d) in some cases, part of the components of a highly porous layer can be introduced by impregnation of the product, followed by drying and calcination.

The invention is illustrated by the following examples:

Example 1. The aluminum powder is mixed with powdered iron is poured into the molding device in which pre-placed tube of largescale, closed and placed in an autoclave. Autoclave molding device steamed, then remove the molding device from the autoclave, is taken out of the molding device, the obtained product is dried and calcined in air. The obtained catalytic element contains highly porous metal oxide composite thickness of 10 mm of the composition of AlxFeaOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,91; Fe - 2,40; oxygen concentration is determined by the degree of oxidation of the aluminum, the valence of iron, the values of x and a.

Example 2. How prepared are made of copper. The obtained catalytic element contains highly porous oxide composite thickness of 10 mm of the composition of AlxFeaOyon the surface of a tube made of copper with a diameter of 4 mm at the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 3,22; Fe - 0,33; oxygen concentration is determined by the degree of oxidation of the aluminum, the valence of Mn, the values of x and a.

Example 3. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of chromium, lanthanum and cerium. The obtained catalytic element contains highly porous oxide composite thickness of 10 mm of the composition of AlxCraLab-zCezOyon the surface of the tube from largescale with a diameter of 10 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,52; Cr - 0,11; La - 0,81; Ce - 1,10; oxygen concentration is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, a, b, z.

Example 4. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of copper, manganese and calcium. The obtained catalytic element contains highly porous metal oxide by consumera 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,53; Cu - 0,06; Mn - 0,06; Ca - 1,52; oxygen concentration is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, a, z, d.

Example 5. The preparation method similar to example 1, characterized in that the composition of the powder mixture includes manganese oxide, and palladium in catalytic element introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite thickness of 10 mm of the composition of AlxMnaPddOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,53; Mg - 0,41; Pd - 0,120; oxygen concentration is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, a, d.

Example 6. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of manganese, cerium, magnesium. The obtained catalytic element containing a highly porous metal oxide composite with a thickness of 2 mm of the composition of AlxMnaCebMgcOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal tostu cations, values of x, a, b, c.

Example 7. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of manganese, lanthanum and sulfur, and palladium in catalytic element introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite with a thickness of 2 mm of the composition of AlxMnaLnb-zCezPddOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,22; Mn - 0,06; Ln - 0,01; Ce - 0,01; Pd - 0,001; oxygen concentration is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, a, b, z, d.

Example 8. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of chromium and magnesium, and palladium in catalytic element introduced by impregnation. The obtained catalytic element containing a highly porous metal-oxide composite with a thickness of 2 mm of the composition of AlxCraMgcPddOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0, values of x, a, c, d.

Example 9. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of manganese, cerium and palladium in catalytic element introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite thickness of 0.6 mm of the composition of AlxMnaCebCacPddOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,02; Mn - 0,02; Ce - 0,01; Ca - 0,01; Pd - 0,002; the concentration of aluminum is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, a, b, c, d.

Example 10. The preparation method similar to example 1, characterized in that the composition of the powder mixture includes aluminum oxide and palladium in catalytic element introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite with a thickness of 2 mm of the composition of AlxPddOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,25; Pd - 0,018; oxygen concentration ODA is for drinking, preparing, similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of calcium and magnesium, and platinum and palladium in catalytic element introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite with a thickness of 2 mm of the composition of AlxCac-zMgzPtd-lPdlOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,14; Ca - 0,02; Mg - 0,04; Pt - 0,001; Pd - 0,001; oxygen concentration is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, c, z, d, 1.

Example 12. The preparation method similar to example 1, characterized in that the composition of the powder mixture includes aluminum oxide and cerium, platinum, palladium and rhodium in catalytic element introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite with a thickness of 2 mm of the composition of AlxCecPtd-z-lPdzRhlOyon the surface of the tube from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,26; Ce - 0,01; Pt - 0,02; Pd - 0,03; Rh - 0,02; S="ptx2">

Example 13. The preparation method similar to example 1, characterized in that the composition of the powder mixture composed of the oxides of lanthanum, cerium, magnesium, as non-porous bases use the rod from largescale and palladium introduced by impregnation. The obtained catalytic element contains highly porous metal oxide composite with a thickness of 2 mm of the composition of AlxLab-zCezMgcPddOyon the surface of the rod from largescale diameter of 6 mm under the following concentrations of the elements of the composite per unit surface area of the metal (g/cm2): Al - 0,22; La - 0,02; Ce - 0,02; Mg Is 0.001; Pd - 0,001; oxygen concentration is determined by the degree of oxidation of aluminum, the valence of the cations, the values of x, b, c, d.

All examples with data on specific surface area, high porosity layer, the concentration of elements included in a highly porous layer per unit surface of the metal carrier and the specific activity of highly porous layer in the oxidation of butane in the table. The analysis of cations in high-porosity layer was performed by atomic-absorption spectrophotometry and flame photometry. The concentrations were rounded to 0.01 g/cm2; the concentration of the platinum metals okrzei argon method BET. The activity of a highly porous layer was determined for fractions 1-2, separated from the metallic base in bigradient conditions at a concentration of Bhutan; a stationary - 0.2 vol% initial - 0,5%; 400oC.

As can be seen from the table, the specific activity of the composites containing platinum metals, high, due to the large concentration of these metals in the unit weight of the composite. Special experiments have shown that, compared with faction specific activity of the composite 2 mm thick, deposited on a metal tube, is reduced by 2-4 times. However, this value is quite high. So, for Mn-containing catalytic element (example 6) it was found that the effective rate constant, referred to the unit volume of the reactor, in which the tube is coated staggered, that is at 300 and 500oC 4400 and 190,000 ml butane/(mlreactorh), respectively. That is, if 300oC and load 25000 h-1low degree of transformation is estimated from the equation for the reactor of ideal displacement: K ln(1-x), will be 16%, which is sufficient for ignition of the oxidation of butane. If 500oC conversion of butane will be about 99%. Released during signint process. However, the use of the catalyst, deposited on a metal tube to stabilize the combustion process of fuels, to prevent overheating and to reduce wear.

1. The method of preparation of the catalyst (catalyst element) on the basis of a metal tube or rod for deep oxidation of hydrocarbons and carbon oxide deposited on the tube surface of the catalyst layer comprising a mixture of insoluble or low-solubility compounds with powdered aluminum, then filling in the moulder and processing of water vapor, characterized in that the forming device together with the powder components is placed a metal tube or rod, and after the steam treatment of the formed product is removed from the molding device, dried and calcined, with the catalytic layer is a thick, highly porous, samozakravatayasa floor the next coating thickness , mm :

of 0.6 < < 10,0.

2. The method of preparation under item 1, characterized in that the insoluble or low-solubility compounds are used compounds of transition elements or their mixtures, and/or Melo is on all of the above elements, this catalytic layer further comprises a compound based on at least one of the above items.

3. The method of preparation by PP.1 and 2, characterized in that the components of the catalytic layer into it by impregnation tube with a thick coating in solution with subsequent drying and calcination, while the catalytic layer further comprises at least one of the compounds based on platinum metals.

4. The method of preparation by PP.1 to 3, characterized in that the concentration of aluminum in the catalytic layer per unit geometric surface of the metal is

0,02 CAl3,22 (g/cm2).

5. The method of preparation by PP.1 to 3, characterized in that the concentration of transition elements or their mixtures (M) in the catalytic layer per unit geometric surface of the metal is

0 < CM2,40 (g/cm2).

6. The method of preparation by PP.1 to 3, characterized in that the concentration of rare earth elements, or mixtures thereof in the catalytic layer per unit geometric surface of the metal is

0 < CR1,91 (g/cm2).

7. The method of preparation by PP.1 to 3, characterized by tech metal surface is

0 < CA1.52m (g/cm2).

8. The method of preparation by PP.1 to 3, characterized in that the concentration of platinum metals or their mixtures (Me) in the catalytic layer per unit geometric surface of the metal is

0 < CMe0,120 (g/cm2).

 

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