The preparation method of catalyst for the conversion of so2in so3

 

(57) Abstract:

Describes the method of preparation of the catalyst the conversion of SO2in SO3that includes getting hydrocephalia, the mixing of the carrier with solutions of active ingredients, drying the slurry, forming and heat treatment, characterized in that the receiving hydrocephaly lead, treating siliceous material alkaline solutions of active ingredients, with the extraction of part of the silica in solution followed by presidenial dissolved silica sulfuric acid in the presence of solid particles of undissolved media, the siliceous material use natural or/and synthetic silica content (based on the substance calcined at 600oC), wt. %: SiO2not less 86,0, (Al2O3+Fe2O3) no more than 11,0, and the molar ratio of SiO2/(K2O+Na2O)-V2O5when processing siliceous material by alkaline solutions change in the range of 3.5-20,8, and the degree of extraction of SiO2in the solution support in the range of 0.14 to 0.85. The technical result - improved stability of catalytic activity over time. 5 C.p. f-crystals, 1 table.

The invention relates to Catalytica preparation method of catalyst for the conversion of SO2in SO3[a.c. USSR N 1113165 "Method of preparation of the catalyst for oxidation of sulfur dioxide", class. B 01 J 37/4 B 01 J 23/22, 1982, BI N 34, 1984], which includes a mixture of a carrier obtained by drying hydrocephaly, with solutions of active ingredients followed by molding and heat treatment. The method allows to obtain a catalyst with high mechanical strength and stability of activity. The disadvantage of this method is the low value of the initial activity of the catalyst.

A known catalyst for the conversion of SO2in SO3made in the following way. Hydrocephaly obtained from liquid sodium glass additive first of ammonium sulfate, and then sulfuric acid, followed by filtration and washing. Next, mix the media with active components, dried, molded and thermoablative. This method allows you to obtain a catalyst with high activity at low temperatures (420oC) [and.with.USSR N 1616688 Catalyst for the conversion of SO2in SO3" B 01 J 23/22, C 01 B 17/69, 1987, BI N 48, 1990]. The disadvantage of this method is the low stability of the catalyst activity with time at low temperatures.

The aim of the invention is to increase the stability of the catalytic act of the stick and high performance through the use of a number of techniques.

This goal is achieved in that the method comprises obtaining hydrocephalia, the mixing of the carrier with solutions of active ingredients, drying the slurry, forming and heat treatment. While getting hydrocephaly lead, treating siliceous material alkaline solutions of active ingredients, with the extraction of part of the silica in solution followed by presidenial dissolved silica sulfuric acid in the presence of solid particles of undissolved media.

As the siliceous material use natural and/or synthetic silica (including waste production) with the content of SiO2no less than 86 wt.%, (Al2O3+ Fe2O3) not more of 11.0 wt.% (based on the substance calcined at 600oC). The molar ratio in the processing of siliceous material by alkaline solutions change in the range of 3.5 - 20,8. The degree of extraction of SiO2in the solution support in the range of 0.14 to 0.85.

The particle size of the carrier is less than 3 mm, the moisture content of the pulp during processing of the medium alkaline solutions of active ingredients maintain at least 55%, while the slurry is stirred at a temperature of 35 - 100oC for 0.5 - 20 hours Pereosazhdeniya solution the media take the value of specific surface area of not less than 5 m2/, the Content of Al2O3and Fe2O3if necessary, reduce the preliminary washing with solutions of acids.

Standard tests of the activity of the catalyst are within 6 h, but increasing the duration of the test, for example up to 50 h, the activity value can be drastically reduced. This is because the catalyst under reaction conditions undergoes transformations, which do not have time to come to equilibrium for 6 h, so the duration of 50 hours, especially for testing at low temperatures, is more objective characteristic.

The test results presented in the table.

Changes in the activity of the catalyst over time, i.e., the stability, activity, achieved by the creation of special structures and composition of the catalyst. Removing only part of the silica in the solution, followed by its precipitation occurs in the presence of solid particles of undissolved carrier, i.e. a special structure "fresh globules in the environment of solid particles". It is possible, to a large extent it determines the stability of the catalyst activity. Silicon dioxide as a carrier, in addition, participates in catalysis chemically stabilizing aktiviranje SiO2in silica, less than 86%, the stability of the activity at t = 420oC is significantly reduced.

When used as the siliceous material is a mixture of two or more carriers, the total content of these indicators should remain in the same position.

When the impurity content of Al2O3and Fe2O3more than 11% reduced activity of the catalyst at 420oC and after 6 and after 50 hours of testing. This is due, apparently, to the fact that as aluminium and iron enter into a chemical reaction with the potassium of the active complex and, thus, "limit" active complex. Because the rate of this process is limited by diffusion factors, the negative influence of these impurities is particularly noticeable with longer duration of operation of the catalyst.

The negative impact of the admixture of aluminum in the silica is known, however, a decisive role is played by the presence of the total content of Al2O3and Fe2O3because both of these elements can form alum. For example, when a low content of Al2O3(see example 12) - 3%) and high Fe2O3- 9% of the activity of the catalyst at 420oC small. Thus, the smaller the content of the activity.

The content of the components is given in relation to the substance calcined at 600oC, i.e., when the operational temperature of the catalyst, to ignore the content of the burnable or decomposing impurities, receding at the stage of calcination of the catalyst.

The formation of the rational structure of the media possibly in the range of the degree of extraction of SiO2and the solution is in the range from 0.14 to 0.85. The value of a specific value is selected depending on the porous characteristics of the original siliceous material, which can be patchy, especially in natural materials and waste industries. The degree of extraction less 0.14 insufficient to stabilize the active complex and leads to a decrease in catalyst activity. The increased recovery of more than 0.85 insoluble parts is insufficient for the formation of structure in the "fresh globules in the environment of solid old particles, and the activity and stability of the catalyst is low.

The ratio allows more accurate than SiO2/K2O, ask the stoichiometric ratio of K2O + Na2O and SiO2that should translate into a solution in the case when the alkali treatment is used Vanadate, potassium and sodium is that a wide range of chemical composition of the catalyst with high performance properties, because alkali metals and V2O5introduced into the pulp at alkaline treatment siliceous carrier, then not removed from the catalyst composition. With increasing ratio of more than 20.8 reduced percentage of the active complex catalyst and its activity as at 420 and 485oC. With reduction ratios below 3,5 reduced content of the carrier in the catalyst, it causes a decrease in the stability of its activity.

The particle size of the carrier should not exceed 3 mm, because otherwise dissolved particles decreases the rate of dissolution is determined by the size of the interfacial surface. For nerastvorim particles decreased rate of impregnation.

The value of the moisture content of the pulp is determined by the requirements to the hardware design process, at a relative humidity less than 55%, the fluidity of the slurry is low, transport and mixing difficult.

The boundaries of the intervals of temperature and duration of mixing associated with a given degree of extraction of SiO2. So, to achieve a low degree of extraction of the duration of mixing of the pulp is at least 0.5 hours at least to achieve a uniform composition of the pulp by volume of the device.

For d and further increase the time performance of the apparatus falls with a slight increase in the degree of extraction.

When reducing the process temperature below 35oWith sharply reduced the rate of dissolution of SiO2the upper temperature limit due to undesirable boiling pulp.

The pulp density in presideni dissolved silica sulfuric acid determines the structure formation "fresh globules in the environment of solid particles and must be in the range of 1.05 - 1.13 g/cm3. It was established experimentally that at lower values than 1,05 g/cm3decreases the activity of the catalyst at 485oC, higher than 1.13 g/cm3that decreases the activity of the catalyst at a temperature of 485oC. the temperature of the slurry may vary within a wide range from 17 to 95oC. However, at temperatures below 17oC stability activity worsens, the upper limit due to the undesirability of boiling pulp.

The foregoing process conditions allows to obtain a catalyst with a satisfactory performance characteristics, using natural and synthetic media with the different value of specific surface area, and even with the use of waste products. However, the lower limit of the specific surface area is limited, but not the debtor is WKR decrease.

Comparative analysis of the proposed solutions and prototype shows that the claimed solution is distinguished by the following characteristics: the content in the media SiO2that is, the total content of impurities of Al2O3and Fe2O3, the molar ratio of Some of them overlap with the prototype (in the range), but they cause the appearance of a new enhanced effect, not previously described, the improved stability of activity. Thus, the claimed method meets the criterion of "novelty."

The comparison of the proposed solutions with other technical tasks shows that the use of a number of the above technical solutions are known, but in this case they allow while preserving the positive characteristics of the prototype to get a new effect - increased one of the basic properties of the catalyst.

Example 1.

To prepare 100 g of catalyst a 35.8 g of dry synthetic silica (based on the substance calcined at 600oC) with a particle size less than 3 mm, with the size of the specific surface area of 5.0 m2/g content (based on the substance calcined at 600oC), wt.%: SiO2- 86,0, (Al2O3+Fe2O3) - 4,9 mix the soy in the pulp corresponds to 3.5. The pulp is diluted with water to a moisture content of 65%, heated to 40oC and stirred for 20 hours, the Degree of extraction SiO2in the solution thus corresponds to 0.85. The slurry is further diluted with water to achieve the density of the stock solution of 1.05 g/cm3, cooled to 17oC and then periostat dissolved silica, adding to the pulp to 10.6 ml of a solution of sulfuric acid - 92,5% to pH 7.5. The slurry is stirred for 2 h, after which impose solutions of active ingredients to achieve a given catalyst composition, namely 13,2 ml of sulfuric acid - 92,5% and 52 ml of KOH solution with a content of K2O - 50 g/l Slurry is dried, the powder ekstragiruyut moisture 39,4%.

The catalyst has a composition, wt.%:

V2O5- 10,0

K2O - 21,4

SO3- 32,8

Media - Rest

Example 2.

The catalyst prepared according to example 1 using synthetic silica with a specific surface area 620,9 m2/g content (based on the substance calcined at 600oC), wt.%: SiO2at 99.1, (Al2O3+Fe2O3) is 2.1.

The molar ratio is 20,8, and the degree of extraction of SiO2in the solution of 0.14. When presideni dissolved silica of platnost who meet the composition, wt.%:

V2O5- 7,0

K2O - 8,9

SO3- 13,7

Media - Rest

Example 3.

The catalyst prepared in accordance with example 1 using synthetic silica with a specific surface area 27,4 m2/g content (based on the substance calcined at 600oC), wt.%: SiO2- 87,8, (Al2O3+Fe2O3) is 11.0. of 47.1 g (based on the substance calcined at 600oC) silica mixed with 92 ml of a solution of potassium Vanadate with a content of 100 g/l V2O5and 171,7 g/l K2O. the Molar ratio of 5.9, and the degree of extraction of SiO2in the solution of 0.51. When presideni dissolved silica density of the stock solution corresponds 1,10, and the temperature of the pulp - 25oC.

The catalyst has a composition, wt.%:

V2O5- 9,2

K2O - 17,3

SO3- 26,4

Media - Rest

Example 4.

The catalyst prepared in accordance with example 3. Synthetic silica is mixed with 110 ml of KOH solution with a content of 100 g/l K2O.

In the pulp after the resultant deposition rates of dissolved silica impose solutions of active ingredients to achieve a given composition, namely sulfuric S="ptx2">

The catalyst prepared in accordance with example 3. Synthetic silica is mixed with 92 ml of alkaline Vanadate solution with a content of 100 g/l V2O5, 119,6 g/l K2O and 38.0 g/l Na2O.

The catalyst has a composition, wt.%:

V2O5- 9,2

K2O - 12,0

Na2O - 3,5

SO3- 26,4

Media - Rest

Example 6.

The catalyst prepared in accordance with example 3 using diatomite content (based on the substance calcined at 600oC), wt.%: SiO2- 84,3, (Al2O3+ Fe2O3) is 11.9. Before mixing with a solution of potassium Vanadate diatomaceous earth is mixed with water at T:W=1:4 add sulfuric acid - 92,5% to obtain the concentration of H2SO4in the mother solution of 15%, the slurry is heated to 70oC, stirred for 4 h, the residue is filtered and washed with water at the rate of 10 liters per 1 kg of dry sediment. Washed so diatomite contains (based on the substance calcined at 600oC), wt.%: SiO2- 94,2, (Al2O3+Fe2O3) is 1.2.

Example 7.

To prepare 100 g of the catalyst of 23.5 g (based on the substance calcined at 600oC) diatomite with a specific surface area of 35,B>3+Fe2O3) is 11.9 mix from 23.6 g (calcined substance) of synthetic silica (waste production) with a specific surface area 750,3 m2/g and the content (based on the substance calcined at 600oC), wt.%: SiO2- 91,3 and (Al2O3+Fe2O3) to 3.0. The mixture of the carriers further mixed with a solution of potassium Vanadate and get the catalyst in accordance with example 3.

Example 8 (comparison).

The catalyst was prepared in accordance with example 3 with the use of diatomaceous earth with a specific surface area of 35.2 m2/g, and content (based on the substance calcined at 600oC), wt.%: SiO2- 84,3, (Al2O3+Fe2O3) is 11.9.

Example 9 (for comparison).

The catalyst prepared in accordance with example 1. The value of the specific surface of the synthetic silica - 4.1 m2/,

Example 10 (for comparison).

The catalyst prepared in accordance with example 2. The molar ratio is 22,0, the degree of extraction of SiO2in a solution of 0.10.

The moisture content of the pulp during processing of silica alkaline solutions - 58%, temperature - 35oC, mixing time 0,3 including the density of the stock solution in vs is="ptx2">

The catalyst prepared in accordance with example 3. The molar ratio is 3.2, the degree of extraction of SiO2in the solution of 0.93. The moisture content of the pulp during processing of the alkaline silica solution - 75%, temperature - 100oC, mixing time is 20 hours, the Density of the mother liquor in the pulp before presidenial dissolved silica - 1,03 g/cm3.

Example 12 (for comparison).

The catalyst was prepared in accordance with example 8. Content, wt.%: (Al2O3+Fe2O3) is 11.9, including Al2O3to 3.0, Fe2O3- 9,0.

1. The preparation method of catalyst for the conversion of SO2in SO3that includes getting hydrocephalia, the mixing of the carrier with solutions of active ingredients, drying the slurry, forming and heat treatment, characterized in that the receiving hydrocephaly lead, treating siliceous material alkaline solutions of active ingredients, with the extraction of part of the silica in solution followed by presidenial dissolved silica sulfuric acid in the presence of solid particles of undissolved media, the siliceous material use natural or/and synthetic silica content+ Fe2O3) - Not more than 11,0

and the molar ratio of SiO2/(K2O + Na2O) V2O5when processing siliceous material by alkaline solutions change in the range of 3.5 - 20,8, and the degree of extraction of SiO2in the solution support in the range of 0.14 to 0.85.

2. The method according to p. 1, characterized in that the use of media with a particle size less than 3 mm

3. The method according to PP.1 and 2, characterized in that the moisture content of the pulp during processing of the medium alkaline solutions of active ingredients maintain at least 55%, while the duration of mixing of the pulp is 0.5 - 20 h at 35 - 100oC.

4. The method according to PP.1 to 3, characterized in that pereosazhdeniya dissolved silica conduct of the pulp with a density of stock solution of 1.05 - 1.13 g/cm3when 17 - 95oC.

5. The method according to PP.1 to 4, characterized in that the specific surface area of the siliceous material is not less than 5 m2/,

6. The method according to p. 1, characterized in that to reduce the content of impurities of Al2O3and Fe2O3and to increase the content of SiO2carrier pre-washed with acid solutions.

 

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FIELD: oxidation catalysts.

SUBSTANCE: SO2-into-SO3 conversion catalyst contains following active components: vanadium oxide, alkali metal (K, Na, Rb, Contains) oxides, sulfur oxides, and silica framework formed from natural and/or synthetic silica and having pores with radii up to 65000 , among which fraction of pores with radii larger 10000 does not exceed 50%, while content of sulfuric acid-insoluble vanadium compounds (on conversion to V2O5) does not exceed 4.0% by weight. Fraction of pores with radii 1000-10000 does not exceed 35% and that less than 75 at most 9%.

EFFECT: improved performance characteristics of catalyst operated in reactor zones at medium and maximum temperature due to under conditions activity at 420-530оС.

3 cl, 1 tbl, 8 ex

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