KR100187582B1 - Preparation of catalyst containing group viii metal and non-acidic promoter dispersed on a support via simultaneous impregnation - Google Patents

Abstract

The present invention comprises a) mixing a first aqueous solution containing a chelating agent and at least one accelerator metal salt and heated to a temperature between 80 ° C. and its boiling point and a second aqueous solution containing at least one Group VIII metal compound. Obtaining a solution; b) aging the mixed solution at a temperature of 40-100 ° C. for 5 minutes to 4 hours; c) impregnating the aged mixed solution onto a solid refractory oxide support to obtain an impregnated solid support; d) calcining the impregnated solid support at a temperature of 300 to 850 ° C. for 10 minutes to 8 hours to obtain a calcined catalyst; And e) reducing the calcined catalyst at a temperature of 300 to 850 ° C. for 30 minutes to 8 hours to obtain a catalyst of the present invention, simultaneously comprising a catalyst containing a Group VIII metal and a non acidic promoter dispersed on a support. It relates to a manufacturing method by the impregnation method.

Description

Method for Producing by Simultaneous Impregnation of Catalyst Containing Group VIII Metal Dispersed on Support and Non Acid Promoting Agent

The present invention relates to a process for the preparation by the simultaneous impregnation of a catalyst containing a Group VIII metal dispersed on a support and a non-acid promoter.

Catalysts containing group VIII metals with modifiers such as alkali metals, tin, germanium, lead, indium, gallium and the like are known in the art. For example, US Pat. No. A4914075 discloses a dehydrogenation catalyst consisting of a Group VIII metal component, an alkali metal component, an alkaline earth metal component, and a component selected from tin, germanium, lead, indium, gallium, thallium, or mixtures thereof. have. This catalyst is prepared by impregnating a target component on a support. It is also known that chelating ligands can be used to impregnate a metal on a support. For example, US Patent A479196 discloses the preparation of a catalyst using a solution containing ethylenediaminetetraacetic acid (EDTA), a noble metal and ammonia.

The inventors have discovered a process for the preparation of a catalyst consisting of simultaneously impregnating a Group VIII metal and a non acidic promoter metal using a chelating ligand. The method includes preparing a solution containing a chelating ligand such as EDTA and an accelerator metal. This solution is heated, then mixed with a solution containing a Group VIII metal compound and the resulting mixed solution is aged. This aged solution is then used to impregnate a refractory oxide support such as Θ-alumina, followed by calcination and reduction to obtain the desired catalyst in which both the promoter metal and the Group VIII metal are dispersed on the support.

The present invention relates to a method for producing a catalyst by a simultaneous impregnation method. This catalyst consists of a Group VIII metal and a non-acidic modifier metal dispersed on a solid refractory oxide support. Thus, one embodiment of the present invention comprises a) a first aqueous solution containing a chelating agent and at least one promoter metal salt and heated to a temperature between 80 ° C. and its boiling point and at least one Group VIII metal compound. 2) mixing the aqueous solution to obtain a mixed solution, b) aging the mixed solution for 5 minutes to 4 hours at a temperature of 40 to 100 ℃, c) impregnated by impregnating the aged mixed solution on a solid refractory oxide support Obtaining the calcined catalyst, d) calcining the impregnated solid support at a temperature of 300 to 850 ° C. for 10 minutes to 8 hours to obtain a calcined catalyst and e) calcining the catalyst at a temperature of 300 to 850 ° C. Reduction for from minutes to 8 hours to obtain a catalyst of the invention.

In another embodiment, the catalyst obtained by the above process is treated with a hydrogen chloride / chlorine stream for a period of 30 minutes to 8 hours at a temperature of 300 to 850 ° C.

In another embodiment, aluminum chloride may also be deposited on the catalyst.

The catalyst produced by the present invention consists of a solid refractory oxide support on which at least one Group VIII metal and a nonacid promoter are dispersed. The support can be any of a number of supports known in the art, including alumina, silica / alumina, silica, titania, zirconia, and zeolites. Alumina that can be used as a support includes gamma alumina, theta alumina, delta alumina and alpha alumina, with gamma and theta alumina being preferred. Alumina includes those containing modifiers such as tin, zirconium, titanium and phosphate. Zeolites that may be used include possite, zeolite beta, L-zeolite, ZSM-5, ZSM-8, ZSM-11, ZSM-12 and ZSM-35. The support can be shaped into any desired shape such as spherical, annular, cake, extrudates, powder, granules and the like, and can be used in any particle size. The preferred form is spherical and the preferred particle size is about 1.59 millimeters in diameter, but 0.79 millimeters and smaller particles can also be used.

One method for producing spherical alumina supports is by the known oil drop method described in US Pat. No. A2620314, which is incorporated herein by reference. The oil drop process is any technique known in the art, preferably an oil bath in which an aluminum metal is formed by reacting aluminum metal with hydrochloric acid, the hydrosol is combined with a suitable gelling agent, and the resulting mixture is maintained at elevated temperature. It consists of dripping into. The mixture droplet remains in the oil bath until it cures to form a hydrogel sphere. The spheres are then collected continuously from the oil bath and usually undergo special aging and drying treatments in oil and ammoniacal solutions to further improve their physical properties. The resulting aged and gelled spheres are washed and dried at a relatively low temperature of 80-260 ° C. and then calcined at a temperature of 455-705 ° C. for a period of 1-20 hours. This treatment results in the conversion of the hydrogel to the corresponding crystalline gamma alumina. Theta alumina is calcined, if necessary, at a temperature of 950-1100 ° C.

The Group VIII metal or metals are dispersed on the desired support in the following manner. First, an aqueous solution of a chelating ligand and one or more nonacidic promoter salts is prepared. Chelating ligands that can be used in the methods of the present invention include amino acids that do not leave harmful components on the support, such as sulfur, upon degradation. Specific examples of these amino acids include ethylenediaminetetraacetic acid, nitrilotriacetic acid, N-methylaminodiacetic acid, iminodiacetic acid, glycine, alanine, sarcosine, α-aminoisobutyric acid, N, N-dimethylglycine, α, β- Diaminopropionate, aspartate, glutamate, histidine and methionine.

Another necessary component of this first solution is the salt of the non-acidic metal promoter. The metal promoter is selected from the group consisting of alkali metals and alkaline earth metals. Examples of salts of these promoter metals that can be used include potassium hydroxide, lithium hydroxide, sodium hydroxide, cesium hydroxide, magnesium hydroxide and the like. The resulting solution is heated to a temperature of about 80 ° C. to its boiling point, preferably 90 to 102 ° C. The ratio of chelating ligand to metal salt will range from 1 to 8, preferably from 1.5 to 4.

The first solution is mixed with a second aqueous solution containing at least one Group VIII metal compound. Among the Group VIII metals that can be dispersed on the desired support, preferred metals are rhodium, palladium, platinum, nickel, cobalt and iron, more preferred metals are rhodium, palladium and platinum, and the most preferred metal is platinum. Examples of Group VIII metal compounds usable in the process of the present invention include platinum chloride, palladium acid, tetraamine platinum chloride, tetraamine palladium chloride, platinum hydrobromide, rhodium chloride, ruthenium chloride, gallium nitrate, nickel chloride, nickel nitrate, Cobalt nitrate, iron nitrate and iron chloride.

The first and second solutions are mixed to form a complex between the Group VIII metal and the chelating ligand. Metal promoters can also be part of the complex. In order to form the complex, the ratio of the chelating ligand to the Group VIII metal is 0.5 to 30, preferably 5 to 13. This ratio depends on the concentration of the promoter metal and the Group VIII metal, with higher ratios being preferred for higher concentration metals. The concentrations of the Group VIII metal and the promoter metal may vary considerably, but are selected to provide concentrations on the support which are expressed in weight percent (as metal) of the support, respectively, from 0.2 to 1 weight percent and from 0.5 to 3 weight percent.

Further, the above-mentioned first solution of ammonium hydroxide and the general formula _{NR 1 R 2 R 3 R 4} + X - ( wherein, R _1, R _2, R _3, R ₄ are each methyl, ethyl, propyl, butyl or t- Butyl, X is hydroxide, and a basic compound selected from the group consisting of quaternary ammonium compounds. The purpose of adding one or more of these basic compounds is to adjust the pH of the solution to vary the distribution of the metal. That is, in some cases it may be desirable to make the distribution of metals uniform, while in other cases it may be desirable to have a higher concentration on the surface. In addition, the distribution of the Group VIII metal may be different from the distribution of the accelerator metal.

While not wishing to be bound by any one theory, there appears to be a constant relationship between the isoelectric point of the support (IEP) and the pH of the impregnation solution. Thus, if the IEP is high, say 8, and the pH is low (1-2), strong bonding or chemisorption will cause surface impregnation of the metal. By raising the pH to 6-9, a substantially uniform distribution will be obtained. Likewise if both IEP and pH are low, a uniform distribution of metals will occur.

After the mixed solution is obtained, it is aged for 5 minutes to 4 hours at a temperature of 40 to 100 ° C. The aged mixed solution is used to deposit the metal on the support by means known in the art. Examples of such means include spray impregnation and evaporation impregnation. Spray impregnation involves taking a small amount of mixed solution and spraying it onto the support while moving the support. When the spray is finished, the wet support can be delivered to another device for the drying or finishing step.

One specific method of evaporation impregnation involves the use of a steam-jacket rotary dryer. In this method, the support is immersed in the impregnation solution located in the dryer, and the support is tumbled by the rotary motion of the dryer. Evaporating the solution in contact with the tumbling support is facilitated by applying steam to the dryer jacket. The impregnated support is then dried at a temperature of 60 to about 300 ° C. and calcined at a temperature of 300 to 850 ° C. for 30 minutes to 8 hours to obtain a calcining catalyst. Finally, the calcined catalyst is reduced by heating the catalyst under a reducing atmosphere, preferably dry hydrogen, at a temperature of 300 to 850 ° C. for 30 minutes to 8 hours. This allows the Group VIII metal to be in the metal or zero state.

Optional steps in the process of the invention include oxychlorination of the above-described calcination catalyst prior to the reduction step. If such a step is desired, a calcination catalyst is placed in the reactor, and a stream containing chloride or chlorine is passed through the catalyst at a flow rate of 0.9 to 18 kg / hr (2 to 40 lb / hr) at a temperature of 300 to 850 ° C. for 10 minutes to Spend six hours. The air stream can be a hydrogen chloride / chlorine stream, a water / HCl stream, a water / Cl ₂ stream or a chlorine stream. The purpose of this step is to provide optimum dispersion of the Group VIII metal and to provide a certain amount of chloride on the final catalyst.

In addition to the above-described catalyst components, other components may be added to the catalyst. For example, a second modifier metal selected from the group consisting of tin, germanium, lead, indium, gallium, thallium and mixtures thereof can be added to the catalyst. This second modifier metal may be added to the support during the preparation of the support, for example by adding a solution of a metal compound to the hydrosol, or before or after impregnation with a Group VIII metal and a non-acid promoter. It may be impregnated into the phase. Impregnation onto the support is carried out in a similar manner as described above using an impregnation solution suitable for the second modifier metal.

When the catalyst is used for alkylation, the catalyst may also contain metal halides having Friedel-Crafts activity. Alkylation herein means alkylation of C ₂ -C ₆ olefins with alkanes having 4-6 carbon atoms. This type of alkylation usually means alkylation of automotive fuels. This metal halide is deposited on the catalyst after the catalyst is calcined and optionally reduced by oxychloride digestion. Metals with Friedel-Craft activity include aluminum, zirconium, tin, tantalum, titanium, gallium, antimony and mixtures thereof. Preferred metals are aluminum, gallium, boron and mixtures thereof. Suitable halides include fluorides, chlorides and bromide. Representative examples of such metal halides include aluminum chloride, aluminum bromide, ferric chloride, ferric bromide, zirconium chloride, zirconium bromide, boron trifluoride, titanium tetrachloride, gallium chloride, tin tetrachloride, antimony fluoride, tantalum chloride, and fluoride Tantalum and the like. Of these metal halides, aluminum halides are preferred, and aluminum chloride is particularly preferred. Boron trifluoride is an exception, but chloride is generally the preferred halide.

These metal halides react with the bound hydroxyl of the support. Thus, for this type of alkylation catalyst, it is required to have hydroxyl bound to the support. The reaction between the metal halide and the bonded surface hydroxyl group of the support is readily accomplished by, for example, subliming or distilling the metal halide onto the particle surface of the support. This reaction is carried out by removing 0.5 to 2.0 moles of hydrogen halide per mole of metal halide adsorbed thereon. The reaction temperature will depend on variables such as the reactivity of the metal halide, its sublimation temperature or boiling point at which the metal halide reacts in the gas phase, as well as the properties of the support. For example, the reaction using aluminum chloride and alumina shown in the examples easily occurs within the range of 190 to 600 ° C.

The amount of metal halide that reacts with the bonded surface hydroxyl groups of the support is generally expressed in weight percent of Friedel-Craft metal on the composite. This amount depends on the support used, the relative number of bound surface hydroxyls of the support (which may be related to the particular oxide phase used), as well as the specific Friedel-Craft metal halides used, as well as the Friedel-Craft-based metal halides. It will vary depending on the particular method used to conduct the reaction between bound surface hydroxyls. As an example, in the case of aluminum chloride on alumina, experience shows that the amount of aluminum chloride represented by weight percent aluminum in the final composite is in the range of 0.1 to 2.5%, and the concentration is primarily of the bound surface hydroxyl groups on the support. It is a function of number.

Several catalysts prepared by the process of the present invention are useful in many hydrocarbon conversion processes. For example, catalysts containing Group VIII metals, in particular platinum, and first modifier metals, in particular potassium, and second modifier metals, in particular tin, have use as dehydrogenation catalysts. Dehydrogenation of hydrocarbons involves contacting the catalyst with a dehydrogenable hydrocarbon in a dehydrogenation reaction zone maintained under dehydrogenation conditions. Such contact may be accomplished using a fixed bed catalyst system, a mobile bed catalyst system, a fluidized bed system, or a batch system, with a fixed bed system being preferred. Hydrocarbons that can be dehydrogenated include hydrocarbons having 2 to 30 or more carbon atoms, including paraffins, alkyl aromatic compounds, naphthenes and olefins. In particular, preferred dehydrogenable hydrocarbons are C 2 -C 6 paraffins, mainly propane and butane.

Dehydrogenation conditions include a temperature of 400 to 900 ° C., a pressure of 1 to 1013 kPa (0.01 to 10 absolute atmospheres) and an hourly space velocity (LHSV) of liquid of 0.1 to 100 hr ⁻¹ . Other conditions and general considerations for carrying out the dehydrogenation process are well known in the art and described, for example, in US Pat. No. A4914075, which is incorporated herein by reference.

The catalyst of the present invention can also be used for alkylation of automotive fuels by adding metal halide functionality. Alkylation of automotive fuels is done by taking a mixture of alkanes and alkenes feed and reacting it with the catalyst required under alkylation conditions. Alkylating conditions include low temperatures on the order of -10 ° C and high temperatures on the order of 100 ° C, depending on the specific feed and catalyst characteristics used. Preference is given to a temperature of 10 to 50 ° C. This reaction is carried out under sufficient pressure to keep the reactants in the liquid phase. The alkylation reaction zone typically uses the catalyst phase required for the mixture of liquid reactants to pass through it with an LHSV of 0.1 to 5.0 hr ⁻¹ .

Example 1

A solution was prepared by combining 262.5 g deionized water, 22.3 g potassium hydroxide solution (39.5% KOH) and 11.6 g EDTA in a flask. The solution was heated to boil and then transferred to a rotary evaporator controlled at 70 ° C. To this evaporator was added a second solution containing 79.1 g of deionized water and 86 g of a solution containing chloroplatinic acid (2.92% Pt). The mixed solution was aged for 45 minutes in the evaporator.

To this aged solution was added 283.5G of gamma alumina spheres containing 0.3% by weight of tin and prepared as described in US Pat. No. A4914075 (Example 1). The temperature was raised to 100 ° C. and the support was rolled for 5 hours.

The impregnated support was then heated to a temperature of 565 ° C. in dry air. When this temperature was reached, an air stream containing HCl and Cl ₂ was flowed through the catalyst for 6 hours.

Finally, pure hydrogen was flowed over the catalyst at a temperature of 562 ° C. for 2.5 hours to reduce the catalyst.

Analysis of the catalyst showed that the catalyst contained 0.75 wt% Pt and 2.2 wt% K. Potassium had a slight concentration gradient (higher at the surface) from the surface of the support inwards, while platinum was evenly distributed throughout the support. This catalyst was referred to as catalyst A.

Example 2

In a flask, a solution was prepared by combining 276.7 g deionized water, 8.1 g potassium hydroxide solution (39.5% KOH) and 4.2 g EDTA. The solution was heated to boil and then transferred to a rotary evaporator controlled at 70 ° C. To this evaporator was added a second solution containing 102.7 g of deionized water and 62.4 g of a solution containing chloroplatinic acid (2.92% Pt). The mixed solution was aged for 45 minutes in the evaporator.

To this aged solution was first prepared gamma alumina spheres (Sn addition) containing 0.3 wt% tin and prepared as described in US Pat. No. A4914075 (Example 1), followed by a temperature of 565 ° C. for 2 hours. 310.5 g of theta alumina spheres prepared by calcining the support was added thereto. The temperature was raised to 100 ° C. and the support was rolled for 5 hours.

The impregnated support was then heated to a temperature of 565 ° C. in dry air. When this temperature was reached, an air stream containing HCl and Cl ₂ was flowed through the catalyst for 6 hours.

Finally, pure hydrogen was flowed over the catalyst at a temperature of 562 ° C. for 2.5 hours to reduce the catalyst.

Analysis of the catalyst showed that the catalyst contained 0.60% Pt and 0.73% K. This catalyst was referred to as catalyst B. The catalyst appeared to be evenly distributed in platinum, but potassium was concentrated on the surface.

Example 3

A solution was prepared by combining 276.8 g deionized water, 7.9 g potassium hydroxide solution (39.5% KOH), 4.17 g EDTA, and 4.0 g tetramethylammonium hydroxide in a flask. The solution was heated to boil and then transferred to a rotary evaporator controlled at 70 ° C. To this evaporator was added a second solution containing 102.34 g of deionized water and 62.8 g of a solution containing chloroplatinic acid (2.92% Pt). The mixed solution was aged for 45 minutes in the evaporator.

In this aged solution, gamma alumina spheres (Sn addition) containing 0.3% by weight of tin and prepared as described in US Pat. No. A4914075 (Example 1) were first prepared, followed by 1037 DEG C. for about 2 hours. 310.5 g of theta alumina spheres prepared by calcining the support to temperature were added. The temperature was raised to 100 ° C. and the support was rolled for 5 hours.

The impregnated support was then heated to a temperature of 565 ° C. in dry air. When this temperature was reached, an air stream containing HCl and Cl ₂ was flowed through the catalyst for 6 hours.

Finally, pure hydrogen was flowed over the catalyst at a temperature of 562 ° C. for 2.5 hours to reduce the catalyst.

Analysis of the catalyst showed that the catalyst contained 0.6 wt% Pt and 0.7 wt% K. Platinum and potassium were evenly distributed across the support. This catalyst was referred to as catalyst C.

Example 4

Catalysts A, B and C were tested for dehydrogenation activity as follows. 20 cc of catalyst heated to about 532 ° C. was placed in a vertical reactor. A reactor comprising isobutane and hydrogen was flowed into the reactor at a H ₂ / HC ratio of 1.0 mol / mol and a LHSV of 20 ^{hr −1} . The conversion over time was measured for the air flow. The test results for each catalyst are shown in the table below.

The data show that Catalyst C with evenly distributed platinum and potassium has the best conversion and selectivity.

Claims (11)

a) mixing a first aqueous solution containing a chelating agent and at least one accelerator metal salt and heated to a temperature between 80 ° C. and its boiling point and a second aqueous solution containing at least one Group VIII metal compound to obtain a mixed solution. B) aging the mixed solution at a temperature of 40-100 ° C. for 5 minutes to 4 hours, c) impregnating the aged mixed solution onto a solid refractory oxide support to obtain an impregnated solid support, d) Calcining the impregnated solid support at a temperature of 300 to 850 ° C. for 10 minutes to 8 hours to obtain a calcined catalyst, and e) reducing the calcined catalyst at a temperature of 300 to 850 ° C. for 30 minutes to 8 hours. A process for producing a catalyst containing a Group VIII metal dispersed on a solid refractory oxide support and a non-acid promoter, comprising the step of obtaining a catalyst. The method of claim 1, wherein the nonacidic promoter is selected from the group consisting of alkali metals or alkaline earth metal salts, and the Group VIII metal is selected from the group consisting of platinum, palladium, rhodium, ruthenium, cobalt, nickel and iron. The method according to claim 1 or 2, wherein the Group VIII metal is platinum and the promoter is potassium. The method of claim 1 or claim 2 wherein the first solution of ammonium hydroxide, and the formula _{NR 1 R 2 R 3 R 4} + X - ( wherein, R _1, R _2, R _3, R ₄ are each methyl, ethyl, Propyl, butyl or t-butyl, and X is a hydroxide, containing a basic compound selected from the group consisting of quaternary ammonium compounds. The catalyst of claim 1 or 2, wherein after step (d), the catalyst is carried out at a rate of 0.9 to 18 kg / hr (2 to about 40 lb / hr) for 10 minutes to 6 hours at a temperature of about 300 ° C to about 850 ° C. Treating with an air stream selected from the group consisting of HCl / Cl ₂ , water / HCl, water / Cl ₂ , and Cl ₂ . The method of claim 1 or 2, wherein after step (e), the metal halide is deposited with a Friedel-Craft activity on the surface of the support by reacting the metal halide with the binding surface hydroxyl on the support. . The method of claim 6 wherein the metal halide is a halide of aluminum, gallium, boron and mixtures thereof. The method according to claim 1 or 2, wherein the chelating agent and the promoter metal salt are present in the first solution at a ratio of 1 to 8. The method of claim 1 or 2, wherein the refractory oxide support contains a modifier metal selected from the group consisting of tin, germanium, lead, indium, gallium, thallium, and mixtures thereof. The chelating agent used in the first solution is ethylenediaminetetraacetic acid, nitrilotriacetic acid, N-methylaminodiacetic acid, iminodiacetic acid, glycine, alanine, sarcosine, α-aminoisobutyric acid. , N, N-dimethylglycine, α, β-diaminopropionate, aspartate, glutamate, histidine and methionine. Catalyst prepared by claim 1.