RU2072898C1 - Method of preparing catalyst for afterburning of organic admixtures in gases - Google Patents

Abstract

FIELD: gas purification. SUBSTANCE: method includes evacuation of globe cracking catalyst carrier and its impregnation with 0.6-0.8 vol.parts of 0.8-2.5 g/l of aqueous solution of H₂PtCl₆ or PdCl₂ per 1 vol.part of carrier followed by sulfidization with hydrogen sulfide and drying. EFFECT: improved preparation procedure. 1 tbl

Description

 The invention relates to catalytic chemistry, in particular, to a method for producing a catalyst for afterburning organic impurities in waste industrial gases and can be used in the chemical and petrochemical industries.

The known method (I) for the preparation of AP-56 alumina-platinum catalyst for afterburning formaldehyde in a flue gas (concentration of 220 mg / m ³ ) and ventilation pipe gases (formaldehyde concentration of 2 120 mg / m ³ ), including the precipitation of aluminum hydroperoxide from a solution of sodium aluminate and 56 % nitric acid, filtering a suspension of aluminum hydroperoxide on a frame filter press, washing the precipitate from sodium nitrate with water, a mold mass in an extrudate with a diameter of 2.8 3.2 mm, length 3 9 mm, drying, calcining an alumina extruded catalyst and in the form of cylinders, at 550 ^o C, impregnation with a 3% aqueous solution of acetic acid, and then with a solution of platinum-hydrochloric acid, drying.

The catalyst AP-56 (TU 38.101.486-77) obtained by the specified method, has a composition, wt. platinum 0.52 0.58; sodium oxide 0.02; the rest is γ alumina. The catalyst according to the specified method reduces the styrene content in the exhaust gas from the production of synthetic rubber from 0.3 to 0.01 mg / l at a temperature of 450 500 ^o C and the space velocity of the gas-air mixture 12000 h ^-1 .

 The disadvantage of this method is the low mechanical strength and thermal stability of the catalyst. After 5 to 6 months. the operation of the catalyst is destroyed, up to 50% of expensive platinum is irretrievably lost.

 Another disadvantage is the complexity of the catalyst preparation technology, the high platinum content and the relatively high temperature of the gas afterburning process.

 There is also known a method (I) for producing an IR-12-1 catalyst, containing 0.40 0.45 platinum supported on alumina promoted by rare earth elements. Carrier extruded alumina is prepared with an additional introduction at the stage of obtaining a suspension of aluminum hydroxide REE in an amount of 1.5 to 5% of the composition of the finished catalyst. Platinum is also applied to the extrudants of the calcined support in excess of an aqueous solution of platinum hydrochloric acid with preliminary treatment with an 8% aqueous solution of acetic acid.

The catalyst, therefore obtained by the method, at 350 ^o C, with a load of 50,000 h ^-1 , with a formaldehyde content of up to 200 mg / m ³ in the exhaust gases, provided a conversion of 95 to 98%
The disadvantage of this method is the complexity of the catalyst preparation technology: precipitation of aluminum hydroxide, filtration, washing, molding, drying, calcining, platinum impregnation of the support, rapid wear of the catalyst extrudants during its operation due to the intense movement in the gas stream of the afterburner, low thermal stability, which leads to the destruction of the catalyst during local overheating at 1000 ^o C in the reaction zone.

A known method (2) of obtaining a catalyst for afterburning organic impurities in gases. The method involves applying to the carrier gA ₂ O ₃ from an aqueous 0.16% solution (ethylene diamine) of platinum chloride, after which the impregnated carrier is dried, calcined in an air stream and activated. Prepared by the method (3), the catalyst afterburns various organic compounds 20-30 ^° C lower than the catalysts obtained by impregnation of the carrier H ₂ PtCl ₆ .

 The disadvantage of this method (3) is the low thermal stability of the catalyst, which at high local temperatures of gas afterburning leads to the destruction of granules and significant losses of platinum, as well as the cylindrical shape of the granules, which is ineffective from the point of view of ensuring the hydrodynamic mode of operation of the catalyst during the afterburning process.

The closest in technical essence and the achieved effect is the method (3) for the preparation of a catalyst, including evacuation and impregnation of an aluminosilicate zeolite-containing base (in the form of a ball). As the crystalline component of the ball, type U zeolite with a molar ratio of SiO ₂ : Al ₂ O ₃ = 4.5 5.5 in an amount of 20-30% by weight to the X-ray amorphous ball aluminosilicate is used.

Zeolite is introduced into a solution of sodium silicate, the formation of balls occurs from sol with a pH of 7.2 and 7.4 in the presence of Al ₂ (SO ₄ ) ₃ in a solution of H ₂ SO ₄ at concentrations of 1 n and 1.2 n, respectively. The balls obtained after coagulation after 1 hour of aging in the mother liquor are activated with a 2% solution of NH ₄ Cl, washed to a negative reaction to chlorine in wash water, then the balls are dried at 150 ^{° for} 4 hours, calcined at 660 ^{° for} 6 hours, and a bulk ball is obtained with a density of 0.56 g / cm ³ and a strength of 7 kg / ball with a ball diameter of 3 mm.

A platinum catalyst containing 0.5% by weight of Pt is prepared by a single impregnation of aluminosilicate beads with a zeolite filler in an aqueous solution of H ₂ PtCl ₆ containing 4.4 g of Pt in a liter of solution. The amount of activating solution is 80% of the volume occupied by the balls. The impregnation is carried out under vacuum (residual vacuum 0,044 at). The solution is served in 0.5 1 min. The catalyst coated with the activating solution is left to impregnate for 1 hour, after which the impregnator is communicated with the atmosphere and the catalyst, together with an excess of H ₂ PtCl _{6, is} discharged into a container in which it is left in the air for 24 hours. Then the catalyst is dried at 110 120 ^o C and calcined at 530 550 ^o C.

 The disadvantage of method (4) is the high concentration (0.5 wt%) of platinum in the catalyst, which makes it very expensive; sophisticated cooking technology: preparing a special ball carrier, calcining, impregnating, drying and calcining again; lack of activity in the afterburn of organic compounds in gases.

 The purpose of the invention is to simplify the technology of preparation of the catalyst, obtaining a catalyst with increased activity, mechanical strength and thermal stability.

This goal is achieved in that the carrier used is a ball cracking catalyst CEOKAR-ZF composition, wt. Al ₂ O ₃ - 8.5; SiO ₂ 90.5; REE 0.5; Na ₂ O 0.3; Fe ₂ O ₃ 0.2 (TU 38.1011114-87), which is evacuated in a cylindrical impregnator to remove air from the pores, is impregnated with platinum (palladium) at 100% absorption from an aqueous solution of H ₂ PtCl ₆ (PtCl ₂ ) at a concentration of it Pt (Pd) 0.8 2.5 g / l with a volume ratio of solution to carrier (0.6 0.8): 1, after impregnation, the catalyst is sulfidized with hydrogen sulfide, dried at 120 ^o C.

.The iron content in the finished catalyst is less than 0.2 wt. in comparison with the carrier CEOKAR-ZF, tk. part of it leaves with a hydrochloric acid impregnating solution, no more than 0.001% remains, which does not affect the decrease in activity of the finished catalyst. The sulfur content in the finished catalyst after sulphurization before its reduction in a stream of hydrogen or in afterburning is 0.08 - 0.16 wt. by reaction

.

The catalyst obtained by the proposed method contains 0.08 0.16% Pt (Pd) instead of 0.4 0.58% in the catalysts obtained by known methods due to the high dispersion of Pt (Pd) on the surface of the new carrier (Ssp ≈ 320 350 m ² / g instead of 180 200 m ² / g for the known method) provides a high degree of purification of gases from organic impurities 99 + 99.5% during the afterburning process in the external diffuse region at a temperature of 300 400 ^o C, which is 50 100 ^o C lower than for the prototype.

The catalyst obtained by the proposed method has high mechanical strength (15 20 kg / ball), high resistance and abrasion (the content of whole and mechanical strong balls after testing in airlift at an air pressure of 2.4 kgf / cm ² 85 87%). The catalyst due to the thermal support of the cracking catalyst "CEOKAR-ZF", processed by calcining at 700 750 ^o C in a stream of flue gases and water vapor, has high thermal stability and does not break at a temperature at 1000 ^o C.

 The resulting catalyst according to the new method provides for 99 99.5% degree of purification of the exhaust gases from styrene, toluene, isopropylbenzene, formaldehyde, oxidation products of the production of higher fatty acids.

Distinctive features of the proposed method from the known is:
1. The use as carrier of a ball aluminosilicate tseolite-containing carrier CEOKAR-ZF with a specific surface area of 320 - 350 m ² / g instead of γ-A ₂ O ₃ .

2. Impregnation of the new support with platinum (palladium) at 100% absorption from H ₂ PtCl ₆ or PdCl ₂ solutions at a volume ratio of the impregnation solution to the catalyst (0.6 0.8): 1 with preliminary evacuation of the support.

 3. The content of Pt (Pd) in the catalyst obtained by the new method, 0.08 0.16 wt. instead of 0.4 0.58 wt. for known methods.

The present invention is illustrated by the following examples:
PRI me R 1. The ball carrier CEOKAR-ZF in the amount of 48 g (volume 80 ml) vacuum for 0.5 h at a residual pressure of 0.002 MPa, prepare 50 mg of an aqueous solution of H ₂ PtCl ₆ (PdCl ₂ ) with a concentration Pt (Pd) 0.8 g / L in it. (The ratio of solution to carrier 0.6: 1), the catalyst is impregnated with 100% absorption for 1 hour, sulphurized for 0.5 hours, dried at 120 ^o C for 4 hours.

The catalyst has a composition, wt. Al ₂ O ₃ = 8.12; SiO ₂ 90.0; REE 1.5; Na ₂ 0.3; Pt (Pd) 0.08. Bulk density 0.65 g / cm ³ , strength 15 kg / ball. The catalyst was tested in the process of post-combustion of isopropylbenzene at Y _gas = 20,000 h ^-1 , temperature 300 500 ^o C. The test results of the catalyst obtained in example 1 and the following are presented in the table.

PRI me R 2. Ball carrier in the amount of 48 g (80 ml) is evacuated for 0.5 hours, prepare 65 ml of an impregnating solution of H ₂ PtCl ₆ or PdCl ₂ (the ratio of the impregnating solution to the carrier of 0.8: 1) , the catalyst is impregnated at 100% absorption for 1 hour with platinum (palladium), grained with hydrogen sulfide, dried at 120 ^o C.

The catalyst has a composition, wt. Al ₂ O ₃ 8.04; SiO ₂ 90.0; REE 1.5; Na ₂ O 0.3; Pt (Pd) 0.16, bulk density 0.68 g / cm ³ , strength 20 kg / ball.

 PRI me R 3. The catalyst is prepared at 100% absorption according to example 1, vol. the ratio of the absorption solution to the carrier is 0.7: 1, the concentration in it of Pt (Pd) is 1.65 g / l.

The catalyst has the composition: Al ₂ O ₃ 8.08; SiO ₂ 90.0; REE 1.5; Na ₂ O 0.3; Pt (Pd) 0.12, us. density 0.60 g / cm ³ , strength 19 kg / ball.

 PRI me R 4. (comparative). The catalyst is prepared according to example 1, however, the volumetric ratio of the impregnating solution to the carrier is 0.5: 1, the concentration of Pt (Pd) in the solution is 0.7 g / L.

The catalyst has a composition, wt. Al ₂ O ₃ 8.14; SiO ₂ 90.0; REE 1.5; Na ₂ O 8.3; Pt (Pd) 0.06, us. density 0.62 g / cm ³ , strength 12 kg / ball.

 PRI me R 5 (comparative). The catalyst is prepared according to example 1, however, about. the ratio of the impregnating solution to the carrier is 0.9: 1 at a concentration of Pt (Pd) of 3.0 mg / L. The carrier impregnation with platinum (palladium) proceeds in excess of the impregnating solution (not according to 100% absorption).

The composition of the catalyst, wt. Al ₂ O ₃ 8.16; SiO ₂ 90.0; REE 1.5; Na ₂ O 0.3; Pt (Pd) 0.04, us. density 0.62 g / cm ³ , strength 8 kg / ball.

PRI me R 6 (comparative). The catalyst is prepared according to example 1, however, the carrier is not evacuated before the solution is impregnated with a metal. The composition of the catalyst, Al ₂ O ₃ 18; SiO ₂ 90.0; REE 1.5; Na ₂ O 0.3; Pt (Pd) 0.02, us. density 0.61 g / cm ³ , strength 6 kg / ball, 50% of the balls are cracked in half.

PRI me R 7. The catalyst is prepared according to example 1 at a concentration of platinum (palladium) in an impregnating solution of 2.5 g / L. The resulting catalyst has a composition, wt. Pt (Pd) 0.25; SiO ₂ 90.0; Na ₂ O 0.3; REE 1.5; Al ₂ O ₃ 7.95. Bulk density 0.70 g / cm ³ , strength 19 kg / ball.

For a concentration of Pt (Pd) of 0.8 g / l, see example 1, the fractional composition of the obtained ball catalyst for all examples corresponds to TU 38.1011114.87 on CEOKAR-ZF, i.e., the content of the target fraction with a diameter of balls of 2.5 ^o C5 is not less than 94%

Claims (1)

A method of producing a catalyst for afterburning organic impurities in gases, including evacuation and impregnation of a ball aluminosilicate tseolite-containing carrier with an aqueous solution of a platinum or palladium compound, subsequent drying of the catalyst, characterized in that the carrier is used as a cracking catalyst CEOKAR-ZF, impregnation is carried out up to 100% absorption of H solution ₂ Pt Cl ₆ or PdCl ₂ at a concentration of platinum or palladium 0.8 2.5 g / l, the volume ratio of the impregnating solution to the carrier (0.6 0.8) 1 and before drying, the catalyst sulfides hydrogen sulfide.

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