CS251054B2 - Method of coating or film application of catalytically active elements - Google Patents

Abstract

The present invention provides a process for applying a coating or film of catalytically active elements by means of solution on the external surface of a porous catalyst support i.e., a catalyst support having a large surface area, characterized in that the catalyst support is impregnated with a solution of at least one of various complexing agents, precipitants and reducing agents in an organic liquid, without exceeding the saturation of the catalyst supports, the solution of catalytically active elements is then added, the liquid is removed by heating and when required, the catalyst support thus treated is subjected to an aftertreatment which is treatment with a reducing agent or tempering at elevated temperature. The process provides a catalyst of uniform quality without a high loss of active components.

Description

The present invention relates to a method of applying a coating or film of catalytically active elements by means of a solution to a catalyst. the outer surface of the porous large-area catalyst supports.

Catalyst supports, also called structural enhancers, are large surface materials onto which a catalytically active substance is deposited in a thin layer. Since the catalytic reactions take place on the surface, this increases efficiency and saves valuable catalytically active substance.

It is known that porous particulate catalyst supports can be sprayed with a concentrated aqueous solution of the salt of the active ingredients, in which the water is substantially deficient in relation to the absorption capacity of the support, to the surface saturation, for example when hot, and then calcined. If necessary, saturation can be facilitated by evacuating the carrier.

Another known method of deposition of catalytically active substances, which is similar to surface saturation, is steam impregnation, in which a hot stream of butane saturated with aluminum chloride is passed through the support and the aluminum chloride settles on the support.

It is further known to dissolve the platinum salts in methanol, acetone, methyl acetate and the like, impregnate the catalyst support with this solution and then ignite it to reduce the platinum. This procedure is described in British Patent No. 496,579.

In another known process, the platinum salts are dissolved in high-boiling organic oils, for example, fish oil boiling above 250 ° C. The solution is deposited on the catalyst support at a penetration depth of not more than 1 mm, and the oil is then removed by heating to ignite. This procedure is described in British Patent No. 5,362,549. 594 463.

These methods have the disadvantage that they must be operated in a closed vessel. Furthermore, uniform coverage of the catalyst support with the active substance is not ensured, so that the catalysts produced are of uneven quality. Another drawback is the high loss of active ingredients.

The purpose of the invention is to develop a surface method; applying an active coating to catalyst supports which do not have the above drawbacks.

The invention is based on the fact that the catalyst support is saturated with an organic solvent and optionally with a solution of clotting, precipitating and / or reducing agents in an organic solvent active against the active element compound, while not exceeding the saturation of the support. the solvent is removed by heating and the catalyst support provided with a catalytically active coating having a maximum cadmium depth of 0.4 mm is optionally subjected to further treatment with reducing agents or tempering at temperatures up to 600 degrees Celsius.

According to the invention, the catalyst support may be saturated with a non-flammable organic solvent such as carbon tetrachloride. According to a preferred embodiment of the process according to the invention, the catalyst support is saturated with a flammable organic solvent, optionally complexing, precipitating and / or reducing agents active against the active element compound and dissolved in the organic solvent are added, not exceeding saturation of the support. solvents which do not adversely affect the flammability of the flammable organic solvent, the flammable organic solvent is allowed to burn, and catalyst supports having a catalytically active coating having a maximum penetration depth of 0.4 mm or less are subjected to further treatment with reducing agents or tempering at temperatures up to 600 degrees Celsius.

The process according to the invention can be carried out on a granulating plate or by means of an auction machine or a heated machine. The burning time of the organic solvent can be controlled by the rate of rotation of the vessel. After the organic solvent has been burned, the catalyst support can be treated with a reducing agent. This can be done, for example, by treating the catalyst for an extended period of time, for example 0.5 to 3 hours, at an elevated temperature of up to 600 ° C with a stream of hydrogen. Other useful reducing agents include forming gas, tormaldehyde, carbon monoxide, hydrazine, hydroxylamine, glyoxal, sulfur dioxide, and the like. The completion of the reaction can be determined by testing the activity of the catalyst.

The catalyst supports to be treated according to the invention are substances with a porous surface which are chemically and physically resistant, i.e., refractory.

Substances meeting these requirements may be of natural and / or synthetic origin. For this purpose, aluminum oxides such as gamma modification of alumina or corundum, silica gel, diatomaceous earth, lime, barium sulphate, magnesium, carbon black, titanium dioxide, iron oxide, zinc oxide, silicon carbide, natural oxide can be used individually or in a mixture aluminum, silicates, pumice, kaolin, asbestos, zeolites and / or magnesium. Depending on the purpose of use, these materials in the form of balls, rings, rollers, cubes, chips and beads can be made into a bulk material or a monolithic catalyst carrier.

Depending on the catalytic reaction, catalyst supports having a large area of about 50 m ² / g, supports having a smaller surface area of about 5 m ² / g having a proportionally larger pore radius, or coarse-grained catalyst supports can be used.

For all structural enhancers, the synergistic interaction between the enhancer (catalyst support) and the active substance (coating or film) can be expected to be greater, the more intense the cross-penetration. Thus, the boundary between the structural and synergistic amplifiers may be movable. Synergic enhancers or promoters impart increased activity or selectivity to one or more of the thermodynamics of possible reactions to the active ingredient or major component of the catalyst. These amplifiers are very diverse in terms of their composition and type of efficiency.

A large number of elements and compounds are used as the main components of the catalysts, in which elements of all groups of the Periodic Table of the Elements except the noble gases are involved. In doing so, one substance can be effective for several or very diverse processes; therefore, it is generally not possible to assign certain substances to certain reactions. For example, copper, silver, gold, chromium, tungsten, molybdenum, iron, cobalt, manganese, nickel, rhodium, platinum, palladium, rhenium, ruthenium and iridium can be used from Groups I, VI and VIII of the Periodic Table. Zinc, aluminum, tin, zirconium, titanium, vanadium, tantalum and magnesium can also be used from groups II, III, IV, V and VII of the Periodic Table. Rare soils such as lanthanum are also useful.

According to the purpose of use may be ^one of the catalytically active elements of the catalyst in a bulk phase used both as metal and as oxide or sulfide in a salt form. The catalysts produced by the process according to the invention are suitable for catalysing chemical reactions in the liquid or gas phase, such as hydrogenation, dehydrogenation, oxidation, dehydration, alkylation or cyclization.

Depending on the type and special nature of the reaction to be catalyzed, the structural enhancer can be coated with the main component so that it does not actually have the synergistic effect of the catalyst support, meaning that the catalytic effect of the metals can be influenced only by the volume phase.

This type of catalyst can be used to produce monolytic exhaust catalytic converters for internal combustion engines. Another possibility of combining is that the main components are applied to a synergistic enhancer, for example a gamma modification of alumina, or the synergistic enhancer is applied to a structural enhancer and a third component, for example a spherical catalyst, is applied as a film or coating. This variant is conceivable, for example, when combining the alpha-modification of alumina (structural enhancer) with the gamma-modification of alumina (synergistic enhancer).

According to the invention, catalyst carriers can be saturated with a flammable organic solvent in the production of catalytically active coatings or films. For this purpose can be used individually or in admixture ^one of alcohols, ketones, ethers and aromatic hydrocarbons. These include, for example, n-butenyl ether, acetone, acetone oils, ethanol, ethyl acetate, ethylbutyrate, ethylene glycol monoacetate, ethylene glycol monoethyl ether, ethylene glycol monnotyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol ether, ethylene glycol ether, ethylene glycol ether ethylene glycol mono-methylether, ethylene glycol mono-ethylethylacetate, ethylene glycol monopropylethylene, ethyl formate, ethylexanoate, ethylpropionate, amyl acetate, amyl alcohol, butanol, butyl alcohol, n-butylformate, benzene, benzene, benzene, 3-Inone methyl ether, butyleneglycol-3-monomethylthylyther-1-acetate, n-butylfummiate, n-butylpnopionate, cyclohexane, cyclohexanol, cyclohexanol acetate, cyclohexanone, cyclohedane, cymene, decahydro-naphthalene, diacetoyl dimethyl ether, diethyl ether, dimethyl ether, diethyl ether , dioxane, fural, glycol carbonate, glycolic acid butyl ether, hexylalcohol, isobutanol, isobutyl acetate, isobutylbutyrate, isoheptylacetate, isoheptyl alcohol, isohexyl acetate, isohexyl alcohol, isopropanol, isopropyl acetate, pine oil, dissolving benzene (solvent naphtha),

5 1 Ο N 4

m.esityloxide, methanol, methyl acetate, methyl ethyl ketone, methyl isobutylcarbinol, methyl isobutyl ketone, methylcyclohexanol, methylcyclohexanol acetate, methylcyclohenainone, methylcyclohexenone, methylene chloride, methylformate, ethyl acetate, butylene methyl ester, n-propylbenzene, n-n-butylbenzene, , propylene glycol etlier, propylene glycol carboinate, n-propylpropronate, carbon disulfide, industrial naphtha, solvenoin M [technical dimethylacetal), turpentine oil and its derivatives, test naphtha, tetrachloroethane, tetrahydrofuran, tetrahydronaphthalene, tetramethylenesulfonate, toluene, trichlorethylene

VMP diesel, turpentine or chloroform.

As solvents in which the catalytically active elements are dissolved, water, alcohols, ketones, ethers, aldehydes and aromatic hydrocarbons can be used singly or in a mixture. In addition, the above-mentioned organic solvents can be used. The mixing ratios can be varied according to the crosslinking catalyst material and the catalytically active element, and must be determined empirically.

For example, in order not to adversely affect the flammability of the organic solvent, for example, the addition of methanol can only be carried out with a maximum amount of water which allows ignition of the methanol.

Catalysts can be present in the solvent as free or complexing ions. Complex compounds may be formed by chelating agents such as acetylacetone, or by addition, such as ammonia. Of particular interest is the use of complex halides, for example chloroplatinic acid. In the organic solvent, complexing, precipitating and / or reducing agents active against the catalytically active compound can be used; element.

For example, the organic solvent may be mixed with hydrogen sulfide, urotropin, ammonia, ammonium polysulfide or ammonium chloride. In doing so, hydrogen sulfide and ammonium polysulfide cause the metal to fix on the support surface, while ammonia and ammonium chloride cause slower diffusion of the metal salts into the carrier. of the interior of the carrier due to complex formation. Do organic. Thus, soluble substances are added to the solvents to convert the catalytically active elements into compounds with reduced solubility (fixation) or compounds with reduced diffusion rate (complexation). Other complexing agents include phosphates, especially metal pyrophosphates and phosphates, citrates, acetams, oxalates, tartrates, -o-phenyantrolene, thiocyanates, thiosulfates, thioureas, pyridine, quinoline, and cyano groups. Halocomplexes such as chlorocomplexes can also be envisaged.

Olefins and olefin-like compounds such as ethylene, propylene, butadiene, cyclohexane or styrene can also be used to form complexes. These complexes can be used in defective systems such as benzene, toluene, pyridine, acetone or diethyl ether.

If a platinum group is used as catalytically active elements of noble metals, a reducing agent can be additionally added to the organic solvent. Such a reducing agent may be, for example, hydrazine, dihydroxylamine, glyoxal, formaldehyde, carbon monoxide and sulfur dioxide. The additional reduction treatment can in this. fall off.

When the monolithic catalyst supports, i.e., one-piece bodies and as such are used in practice, are treated with the process according to the invention, it is expedient to add only enough organic solvent to the monolith to fill approximately 80% of the pores. The remaining 20% of the pores are then filled with a salt-containing solvent.

The process according to the invention has the advantage that the catalytically effective coating uniformly covers the surface of the support. The resulting layer is very thin irrespective of the size of the support because, due to the diffusion of the solvent from the interior of the support, the catalytically active elements are trapped and held on the support surface. A further advantage of the process according to the invention is that it prevents the loss of metal salts.

The process of the invention will be explained in the following examples.

Example 1

110 g of gamma-modified alumina beads with a diameter of 2.8 to 4 mm are rolled in a rotating enamel reaction vessel. 60 ml of a solution consisting of 22 g of chloroplatinic acid and of rhodium chloride in water vials are poured onto these beads with continuous rolling. After drying with a warm stream of air, the beads are treated for 1 hour at 500 ° C with hydrogen.

Example 2

110 g of gamma-modified alumina beads having a diameter of 2.8 'to 4 mm rolling in an enameled rotating plate are saturated with methanol. 15 ml of a solution consisting of 22 g of chloroplatinic acid and rhodium chloride in 1 l of water are then added and this solution is intimately mixed with saturated beads. The methanol is then ignited and completely burnt and then kuhčky / treated with hydrogen at 500 ^C for 1 hour.

Example 1 and id 3

110 g of gamma-modified aluminum oxide beads with a diameter of 2.8 to 4 mm, which are rolled in an enameled rotating plate, are saturated with cyclohexane. 15 ml of a solution of 22 g of chloroplatinic acid and rhodium chloride in 1 l of water are then added and mixed intensively with saturated beads. The cyclohexane is then ignited and allowed to burn completely, after which the beads are treated with hydrogen for 1 hour at 500 ° C.

Example 4

110 g of gamma-modified alumina beads with a diameter of 2.8 to 4 mm are saturated with a saturated solution of hexamethylenetetramine in methanol in the enameled rotating plate while being saturated. While continuously rolling the beads, 15 ml of a solution containing 22 g of chloroplatinic acid and rhodium chloride in 1 l of water are added thereto, and the solution is vigorously mixed with saturated beads. The mixture was ignited and allowed to burn completely. The beads are then treated with hydrogen for 1 hour at 500 ° C.

Example5

110 g of gamma-modified alumina beads with a diameter of 2.8 to 4 mm are saturated with methanol during rolling in an enameled rotating plate and then sprinkled with 15 ml of cold saturated solution of hexamethylenetetramine in methanol. Then 15 ml of a solution containing 22 g of chloroplatinic acid and rhodium chloride in 1 l of water are added thereto, and the solution is mixed thoroughly with saturated beads. The mixture is then ignited and allowed to burn completely. The beads are then treated with hydrogen at 500 ° C for 1 hour.

Example 6

The gamma-modified alumina beads having a size of between 2.38 and 4 mm and a weight of 0.7 to 0.72 kg / l are heated for 2 hours at 800 ° C, after which they have a specific surface area of 43 m ² /G. 10 kilograms of processed beads are saturated in an enamel reaction vessel with 9 L of methanol and allowed to evaporate for 5 minutes to homogenize. While the balls are continuously rolled, 500 ml of an aqueous solution containing 13.1 g of chloroplatinic acid, 4.6 g of rhodium chloride and 26.0 g of aluminum chloride (A1C1 .6 Н О) are added thereto. For homogenization, the beads are allowed to roll for an additional 5 minutes.

The alcohol is ignited and allowed to burn while continuously rolling the loose balls. After the flame was extinguished, the beads were stirred for a further 15 min and then treated for 0.5 h with a stream of hydrogen at 500 ° C.

Example 7

A cylindrical monolithic support body of 100 ml diameter and 150 mm length was coated with an active alumina coating. The support body then had a specific surface area of 13 m ² per gram.

The activated body was then immersed in methanol, excess methanol was expelled by compressed air from its pores, and weighed to reveal that the body soaked 113 grams of methanol (wet weight). The body was then dried to 70% by weight wet and then immersed in an aqueous solution of methanol (92% methanol) containing, in 1 L, 23.8 g of palladium in the form of palladium chloride, 57.4 g of copper nitrate Cu (NO3). 2. 3 H2O, 47.6 g of chromium trioxide * and 61.9 g of aluminum acetylacetonate * A1 (C5H7O2) p. Methanol was then allowed to burn, the support body was calcined in air at 400 ° C for 0.5 h and then treated in a stream of hydrogen at 200 ° C for 15 min.

Example 8 kg of gamma-modified alumina beads, 2.8-4 mm fraction, were saturated with 6 L of carbon tetrachloride according to the method of Example 1 in a rotating plate. Then, 1000 L of an aqueous solution of methanol (40% by weight, methanol) containing 22 g of palladium in the form of palladium chloride was added, then the beads were dried in a hot air stream of 20 ° C and then treated at 50 ° C. for 1 hour in a hydrogen stream of 40 l / h.

Example 9

A cylindrical monolithic support body having a diameter of 100 mm and a length of 75 mm was coated according to Example 8 with an active alumina coating. The carrier body then had a specific surface area of 20 m ² / g.

The pretreated body was immersed in acetone and the pores were then passed through compressed air. The body was then dried to approximately 65% by weight of wet weight and immersed in ethyl acetate containing 21.8 g of platinum in the form of platinum (II) chloride and 143.5 g of chromium oxide. The body was then calcined for 1 hour at 600 ° C in air and subjected to further processing. The catalyst contained 0.5 g of platinum and 2.5 g of chromium trioxide.

Example 10

A quantity of 1 kg of extruded active alumina bodies, having a diameter of 3 min and a length of 3 to 9 mm, was saturated in vacuo with 0.75 L of carbon tetrachloride after 10 min homogenization. 100 ml of an aqueous solution of methanol (95% methanol) containing 13.15 g of chromium trioxide was added continuously, the material was placed in a vacuum rotary evaporator and the liquid components were evaporated while stirring at an oil bath temperature of 80 ^q C The material was then calcined in air at 500 ° C for 0.5 hours.

Example 11 kg of spherical catalyst supports having a bead diameter of 2.8 to 4 mm were saturated in an enameled rotating plate with 8 L of aqueous ammonia solution of methanol (6.3% NH 3). Then, 1000 ml of a methanol solution containing 22 g of platinum in the form of platinum (II) chloride was added, and the nose was treated as described in Example 8.

EXAMPLE 12 kg of 3X3 mm tableted active alumina tablet was saturated with a formaldehyde-containing methanolic solution (8.75% CH 2 SO 2 in an amount of 8 L in an enamelled reaction vessel with continuous rolling of the tablets). aqueous methanol solution containing 95% methanol and 40 g palladium in the form of palladium chloride, after which the tablets were processed as described in Example 1.

To assess the penetration depth of the catalytically active coating and thus the consumption of noble metal salts, the cross section of the processed ball was enlarged photographically by a factor of 100. The width of the dark-colored edge was then measured.

Example The margin width of a photo actually

Example 1 3,5 to 4 cm 0.35 to 0.4 mm the edge does not have a sharp border on the inside Example 2 2,0 to 2.5 cm 0.2 to 0.25 mm Example 3 3.0 cm 0.3 mm Example 4 0.5 to 1 cm 0.05 to 0.1 mm the edge has no inner side sharp border Example 5 0.5 to 1 cm 0.05 to 0.1 mm Example 6 2,0 to 2.5 cm 0.2 to 0.25 mm

The following Table 1 provides an additional overview of Examples 1 to 12 and the substances used.

14

Example Catalyst support Solvent to saturation Komplexotvor. Reducing or precipitating agent Active ingredient Solvent, active ingredients 1 (Cf.) r-AlžCh - - —- Pt / Rh H2O [0.75 kg / l *) 80 m ² / g **)] 2 A12O3 [0.75 kg / l *) 80 m ² / g **) J СНзОН - - Pt / Rh H2O 3 у-АкОз [0.75 kg / 1 *) 80 m ² / g **)] CH6H12 - - Pt / Rh H2O 4 у-АкОз СНзОН hexamethylene- Pt / Rh H2O [0.75 kg / l *) 80 m ² / g **) J tetramine 5 AI2O3 [0.75 kg / l *) 80 m ² / g **)] СНзОН hexamethylene- Pt / Rh H2O 6 у-АкОз tetramin СНзОН (0.7–0.72 kg / l; 43 m ² / g) СНзОН - - Pt / Rh / Al H2O 7 monolith + АкОз СНзОН - - Pt / Cu 92% 13 m ² / g ***) (Cr) Al СНзОН 8 АкОз; CCh - - Pd 40% 0.75 kg / l; 80 m ² / g СНзОН 9 monolith + АкОз; Acetone _ - Pt / Cr acid 20 m ² / g acetic 10 г-АЬОз - extrusion, CC14 molding - - Cr СНзОН (160 m ² / g) 11 y-АкОз - balls (0.8 kg / l; 250 m ² / g) СНзОН NH3 - Pt СНзОН 12 y-АкОз - tablets СНзОН - CH2O Pd СНзОН

(140 m ² / g)

*) bulk density * *) specific surface area ***) specific surface area of combination

In Table 2, Examples 13-28 illustrate additional supports and organic solvents in catalyst production, the depth of penetration of the catalytically active agent into the support, and the force required to crush the grain by the catalyst. Examples 18, 20, 26, 28 are comparative.

Experiment Carrier Organ, Solvent Complexor. Reduction Catalyst. component quantity depth Force in N

Qty. Type of precipitation agent penetration to crush (ml) value grain

CM O

CM

CD CM CO 00 CM in

o CM

CM rH CD

CO * 4 CM CDs' THREE CD IDs

´ Ф CM rH * <Ф CD g CD About CD rH CD £

Cu s s e s s а е * Э and s s

CMCMCMCMCMCDCDOCDCDCD rl Η H rl rl

*********** totototototototototobo ssssssžssss <<<<<<<<<<< 2

CO ^ lDCDbC0O> CDHCMCO Ч Ч Ч Ч cd cd cd cd cd cd ч CD CD CD CD CD CD CD CD CD CD CD 00 00 00

251854

Table 3 illustrates the activity of the catalysts prepared by the process of the invention.

Table 3

Oxidative conversion of carbon monoxide and hydrocarbon

Composition of the test gas sample: Lower residue

H2O 10% vol.

CO 2,25% vol

CsHs 0.04% v / v

Ol 4,4% vol.

Hž 0,75% vol.

NO 0,028% vol

• CO 2 10% vol.

Spatial speed: 42 000 h ^{1 2}

Catalyst according to example

CO conversion (%) at 350 ° C

Conversion of O 3 H 8 (%) at 350 ° C

SUBJECT

Claims (3)

A method of applying a coating or film of catalytically active elements by means of a grid onto the outer surface of porous large-area catalyst supports, characterized in that the catalyst support is saturated with an organic solvent and optionally with a solution of complexing, precipitating and / or reducing agents in an organic solvent active against the active element compound, while not exceeding the saturation of the support, adding a solution of catalytically active elements, removing the organic solvent with heating and catalyst support having a catalytically active coating having a penetration depth of not more than 0.4 mm; subjected to further treatment with reducing agents or tempering at temperatures up to 600 ° C. 2. Method according to claim 1, characterized in that ^iNOS: No catalyst was impregnated with a non-flammable organic solvent. 3. Process according to claim 1, characterized in that the catalyst support is saturated with a flammable organic solvent, optionally with complexing, precipitating and / or reducing agents active against the active element compound and dissolved in the organic solvent, without exceeding the saturation of the support. catalytically active elements dissolved in an amount of solvent not adversely affecting the flammability of the flammable organic solvent are added, the flammable organic solvent is allowed to burn and carry a catalyst coated with a catalytically active coating having a maximum penetration depth of 0.4 mm; tempering at temperatures up to 600 ° C.