DE2348618B2 - PLATING GROUP METAL CATALYST ON AL LOW 2 O LOW 3 CARRIER AND PROCESS FOR ITS MANUFACTURING AND USE OF THE CATALYST - Google Patents

Description

55

The invention relates to a catalyst which contains a platinum group metal on an aluminum oxide support and bound halogen which is at least partially obtained by treating the aluminum oxide support containing 0.1 to 5 percent by weight of platinum group metal, optionally in a pre-reduced state and / or in a reducing atmosphere, with a Friedel Crafts metal halide at a temperature of 100 to 600 ⁰ C until the introduction of 2 to 15 percent by weight of bonded halogen and is incorporated. and a process for its manufacture

as well as the use of the catalyst.

It is known (e.g. DT-PS 12 76611, DT-PS 14 18 447), that catalysts made from a platinum group metal, usually platinum, on a bound halogen, especially chlorine or fluorine containing Aluminum oxide carriers are useful for the isomerization of paraffinic hydrocarbons. Such However, catalysts do not have sufficient activity at low temperatures. on the other hand there is a marked interest in low-temperature isomerization catalysts, in order to be able to exploit the advantages of the more favorable isomer distribution at low temperature. It has been shown that the Desired improved low-temperature activity by simply increasing the halogen content of the catalyst, for example by introducing larger amounts of halogen into the catalyst support by means of an impregnation solution, is not achieved.

There are also catalysts of the type indicated at the outset or procedures for their preparation known (DT-PS 10 48 877, DT-PS 11 56 053), in which a platinum group metal supported alumina catalyst for introducing bound halogen with a Friedel-Crafts metal halide, in particular an aluminum halide, is treated. This improves the low temperature isomerization activity of the catalyst achieved

It is also known (US-PS 32 48 320), platinum group metal-alumina catalysts for the isomerization of paraffinic hydrocarbons with certain polyhalogen compounds, e.g. B. carbon tetrachloride, to treat for halogen introduction. According to a similar known working method (US-PS 34 49 264) are platinum group metal aluminum oxide catalysts with gaseous halogen compounds such as HCl, CI2, HBr, Brj and the chlorine and Treated bromine derivatives of methane to introduce halogen, and then optionally additionally Aluminum chloride can be sublimed onto the catalyst. Through these well-known ways of working an improvement in the low-temperature isomerization activity is also achieved

Despite the improvements achieved, however, the platinum group metal-alumina catalysts prepared by the known procedures are not yet in their activity properties, in particular with regard to the low-temperature isomerization activity fully satisfactory, and there is therefore a keen interest in further improvement.

It is also known to use platinum group metal-alumina catalysts containing bound halogen of the type specified at the outset for improving the activity of hydrocarbon isomerism tion to additionally introduce promoter metals, in particular rhenium (US-PS 36 79 602), germanium (US-PS 36 49 704) or tin (U.S. Patent 36 32 525). Such promoter metals can also be used in the platinum groups metal-aluminum oxide catalysts of the invention or the process for producing this catalyst ren are also used. With special measures for the introduction of halogen, however, this has Nothing to do.

The invention is accordingly the object zugrun de, a catalyst of the type specified zi create, which is characterized by further improved activity properties, especially for the low temperature Isomerization of hydrocarbons

including a process for its manufacture that is simple and reliable to perform

To achieve this object, the invention provides a catalyst which is a platinum group metal on an aluminum oxide support and contains bound halogen, which it at least partially through Handling the 0.1 to 5 weight percent platinum group metal-containing alumina support, if necessary in a pre-reduced state and / or in a reducing atmosphere, with a Friedel-Crafts metal halide at a temperature of 100 to 600 ° C until the introduction of 2 to 15 percent by weight Bound halogen has been incorporated, which is characterized according to the invention in that it contains at least 0.1 percent by weight of further bound “halogen, which after treatment with the Friedel-Crafts metal halide by treatment with a polyhalogen compound from the substance groups of compounds containing at least two halogen atoms on the same carbon or sulfur atom, Boron trihalides, trihalogen derivatives of methane and their methyl substitution products, carbon tetrahalides, Sulfur dihalides, sulfuryl halides, thionyl halides, carbonyl halides and thiocarbonyl tetrahalides has been incorporated in a non-reducing atmosphere at 100 to 600 ° C.

In connection with this, the invention further provides a process for producing this catalyst by treating an alumina support containing 0.1 to 5 percent by weight of a platinum group metal, optionally after pre-reduction and / or in a reducing atmosphere, at 100 to 600 ° C. with a Friedel-Crafts -Metal halide up to the introduction of 2 to 15 percent by weight of bound halogen, which is characterized according to the invention that it is then in a non-reducing atmosphere at 100 to 600 ° C as long with a polyhalogen compound from the groups of at least two halogen atoms on the same carbon or Compounds containing sulfur atoms, _fc boron trihalides, trihalogen derivatives of methane and their methyl substitution products, carbon tetrahalides, sulfur dihalides, sulfuryl halides, thionyl halides, carbonyl halides and thiocarbonyl tetrahalides aftertreated to at least 0.1 weight percent w more bound halogen are introduced.

Preferably, an aluminum oxide carrier is used, which is used before the treatment with the Friedel-Crafts metal halide 0.1 to 2 percent by weight of platinum group metal and 0.01 to 2 percent by weight of a promoter such as rhenium, germanium, tin or Combinations thereof have been incorporated.

Surprisingly, if the according to the invention is adhered to given regulations a catalyst of significantly improved activity properties, in particular for the low temperature isomerization of hydrocarbons. There is also the Adherence to the special sequence prescribed according to the invention for the double halogenation treatment necessary, d. i.e., the one containing the platinum group metal and optionally promoter metal Aluminum oxide carriers must first be successively in the prescribed manner with the Friedel-Crafts metal halide and then with the polyhalogen compound from the prescribed Groups of substances are treated in the manner indicated. With treatment under otherwise identical conditions but in the reverse order, comparably favorable results are not obtained. The same applies when introducing appropriate amounts of bound halogen either only by treatment with a Friedel-Crafts metal halide or only by treatment with a polyhalogen compound of specified type This will be explained in detail using the examples listed below with comparative tests indicated, from which also the case of compliance

The reasons for this unforeseeable improvement are not known in detail
Features and preferred embodiments of the invention are further explained below

For the aluminum oxide carrier, hydrous aluminum oxides or aluminum oxide gels, e.g. B. boehmite, gibbsite bayerite and in particular activated aluminum oxides, which have been treated, for example, at a temperature above 400 ° C. to remove at least part of the chemically and / or physically bound water, can be used. Activated aluminum oxides with a surface area of 100 to 500 m ² / g, in particular gamma- and eta-aluminum oxides produced by heat treatment at 400 to 850 ° C., are preferred.

The alumina support material should be essentially sodium, e.g. B. less than 0.5 Contain weight percent sodium. The alumina support determines the shape of the final Catalyst, e.g. B. balls, pills, granules, extrudate or powder. Balls are preferred. Sodium Free Aluminum oxide spheres can be conveniently and advantageously produced by the known oil drop method in the form of an aluminum oxide sol, similar to the one obtained when aluminum is digested in hydrochloric acid of droplets is dispersed in a hot oil bath, the droplets forming spherical particles are gelled and the latter is then aged, e.g. B. 10 to 24 hours at 50 to 105 ° C, washed, dried and calcined or activated at 500 to 850 ° C.

Platinum, palladium, rhodium, ruthenium, osmium and iridium come into consideration as platinum group metal. Platinum is preferred. The platinum group metal can by any of the known methods with the Aluminum oxide are combined. An impregnation in which the aluminum oxide particles are suspended Dipping or slurrying in contact with an aqueous solution of a platinum group metal compound are brought, is preferred. Suitable compounds are, for. B. platinum chloride, chloroplatinic acid, ammonium chloroplatinate, Dinitrodiamino platinum,

Palladium chloride and chloropalladic acid. A very good impregnation treatment for introducing Platinum consists in impregnating aluminum oxide with an aqueous chloroplatinic acid solution, and that with hydrochloric acid is acidified. The resulting product contains bound halogen, but generally less than 1.5 percent by weight. The aluminum oxide is preferably at least 30% at room temperature Maintained in contact with the impregnation solution for minutes, and then the impregnation solution becomes Evaporated to dryness, for example in a steam-coated rotary steam dryer. Essentially dry impregnated alumina particles are recovered.

The dried material is usually calcined at 375 to 600 ° C in air to convert the platinum group metal into

to convert the oxide form. Preferably the

Aluminum oxide-platinum group metal composition produced in a reduced state For this purpose, the material is expediently ^{treated in an essentially anhydrous hydrogen atmosphere at 425 to 650 °} C. This ensures a uniform and fine distribution of the platinum group metal on the aluminum oxide

The alumina-platinum group metal · -Vorprodukt is then treated at 100-600 ⁰ C with the Friedel-Crafts to Metallhgbgenid so that a reaction of the metal halides occurs with the alumina and a material is formed containing from 2 to 15 weight percent bound halogen containing this purpose the Friedel-Crafts metal halide can be evaporated in a known manner and sublimed onto the aluminum oxide-platinum group metal catalyst, expediently in the presence of hydrogen, nitrogen or another inert diluent gas. Ε ^: τ reducing gas, such as hydrogen, is preferred. The reaction of the Friedel-Crafts metal halide with the aluminum oxide takes place at least partially during the sublimation process. A subsequent heat treatment at a temperature slightly above the evaporation temperature of the Friedel-Crafts metal halide is expedient. Such a heat treatment, which is generally carried out at a temperature of 300 to 600 ^° C., depending on the Friedel-Crafts metal halide used in the individual case, does not promote the reaction of the Friedel-Crafts metal halide with the aluminum oxide with simultaneous evaporation and separation of not converted Friedel-Crafts metal halide, so that the final catalyst composition is essentially free thereof. Friedel-Crafts metal chlorides are preferably used, e.g. B. aluminum chloride, antimony tri- and pentachloride, beryllium chloride, iron (HI) chloride, gallium trichloride, tin (IV) chloride, titanium tetrachloride, zinc chloride, zirconium chloride, boron trichloride. Aluminum chloride is particularly preferred. This sublimed at 178 ° C, suitable vaporization temperatures are between 180 and 55O ⁰ C.

The material obtained is then further treated with a polyhalogen compound from the groups of substances compounds containing at least 2 halogen atoms on the same carbon or sulfur atom (mixed dihalogen compounds), Boron trihalides, trihalogen derivatives of methane and their methyl substitution products, Carbon tetrahalides, sulfur dihalides, sulfuryl halides, thionyl halides, carbonyl halides and thiocarbonyl tetrahalides. Preferred are methylene chloride, chloroform, Methyl chloroform, sulfuryl chloride, thionyl chloride, carbonyl chloride, thiocarbonyl tetrachloride and especially carbon tetrachloride.

While the treatment of the alumina platinum group metal catalyst with the Friedel-Crafts metal halide is preferably carried out in a reducing atmosphere, the treatment with the polyhalogen compound requires a non-reducing atmosphere in order to obtain an active catalyst. The polyhalogen compound can be used as such, but it is preferably mixed with a non-reducing gas, e.g. B. nitrogen, air or oxygen, diluted. Nitrogen is preferred. The treatment with the polyhalogen compound takes place at 100 to 600 ^° C., expediently for a period of 0.2 to 5 hours, until at least 0.1 percent by weight of further bound halogen has been incorporated. Bound halogen resulting from treatment with the Friedei-Crafts metal halide is different from bound halogen resulting from treatment with the polyhalogen compound.

The inventive catalyst is for Kohlenwasserstoffumwandlungsreaktion.en varied at temperatures from 25 to 760 ⁰ C useful. For example, it can be used for the hydrocracking of heavy oils, in which a hydrogenation treatment is carried out to remove sulfur, oxygen and nitrogen impurities; the temperatures then need in no case ^{to exceed 300 °} C., and pressures of 5 to 70 atmospheres are used. However, the catalyst is particularly suitable for the isomerization of paraffinic hydrocarbons, such as η-butane to n-octane or mixtures thereof, and for the isomerization of weakly branched to more strongly branched saturated hydrocarbons, such as the isomerization of 2- or 3-methylpentane to 2,2- and 2,3-DimethyIbutane, and also for the isomerization of naphthenes, z. B. the isomerization of dimethylcyclopentane to methylcyclohexane or of methylcyclopentane to cyclohexane. The catalyst is particularly advantageous for the low-temperature isomerization of straight-chain hydrocarbons having 4 to 6 carbon atoms.

The isomerization of paraffinic hydrocarbons can take place with the catalyst at low levels Temperatures, about 65 to 235 ° C can be carried out. It is useful in the case of a hydrogen / hydrocarbon molar ratio from 0.25: 1 to 20: 1, a pressure between atmospheric pressure and 140 atm. and an hourly space velocity of the liquid d. H. Parts by volume of feed, measured at 15 ° C., from 0.5 to 10 per hour and per part by volume of catalyst

According to a particularly preferred embodiment of the catalyst preparation process, gamma-aluminum oxide, which contains 0.1 to 2.0 percent by weight of platinum, is treated in a hydrogen atmosphere with aluminum chloride to introduce 2.0 to 6.0 percent by weight of combined chlorine, and the composition obtained is then in a Treated nitrogen atmosphere at 150 to 35O ⁰ C with carbon tetrachloride for the further introduction of 0.1 to 5.0 percent by weight of bound chlorine

The same beneficial effects of the double halogenation treatment of the present invention will be obtained achieved with catalysts that contain a promoter metal such as germanium, tin, rhenium. Germanium and tin are better than rhenium. Tin is particularly preferred because it is cheap and moreover one has a slightly better promoter effect than germanium. In each case, the promoter metal is before the double Halogenation treatment introduced into the catalyst. The most favorable are the promoter metals in Combination with platinum, but they can also be used in connection with palladium.

The promoter metals can be combined with the alumina in any conventional manner be e.g. B. by impregnation or ion exchange either before, after or simultaneously with the introduction of the platinum group metal, co-precipitation or joint gelation with the aluminum oxide and subsequent impregnation or ion exchange with

a platinum group metal compound. If tin is precipitated together with the aluminum oxide, it can a soluble tin compound, e.g. B. tin (II) - or tin (IV) chloride, mixed with an aluminum oxide sol before the sol is dripped into a hot oil bath. After the calcination then lies Tin (IV) oxide in intimate association with aluminum oxide. For an impregnation, a Impregnation solution of chloroplatinic acid, hydrochloric acid and tin (II) or tin (IV) chloride is preferred. Instead of HCl, oxalic acid can be used. In the case of germanium, the aluminum oxide is impregnated preferred with the germanium component, e.g. B. using an acidic germanium tetrachloride solution odei of germanium monoxide in chlorinated water. An impregnation solution is particularly preferred from a mixture of chloroplatinic acid solution and germanium monoxide in chlorinated water. In case of Rhenium is also preferred to be impregnated together with the platinum group metal, especially with an impregnation solution of perrhenic acid, chloroplatinic acid and hydrochloric acid.

The final catalyst composition preferably contains 0.01 to 2 weight percent promoter metal and 0.01 to 2 weight percent platinum.

example 1

Sodium free gamma alumina balls from 1.6 mm in diameter, which contained 0.3 percent by weight of combined chlorine, were determined by the oil drop method manufactured. The balls were impregnated with 0.4 weight percent platinum by placing them in an aqueous Chloroplatinic acid solution introduced and the solution then in contact with the balls in one Rotary steam evaporator was evaporated to dryness. The dried impregnated balls were then calcined at 500 to 550 ° C, first two hours in air and then one hour in hydrogen.

50 g of AICI3 were slowly evaporated in a stream of 750 to 1000 cmVmin hydrogen carrier gas, the gas flowing over 125 g of the reduced platinum-impregnated spheres. The AlCl ₃ was fed in at 550 ° C. in the course of 1.5 hours. The spheres were then purged with hydrogen at 600 ° C. for one hour. Then 60 g of CCI4 were slowly introduced into a stream of 2000 cmVmin nitrogen carrier gas which flowed over the spheres. The carbon tetrachloride was added over 1.5 hours at 275 ° C. The catalyst was then ^{flushed with nitrogen at 300 °} C. for one hour in order to remove unreacted carbon tetrachloride. The final catalyst contained 0.4 weight percent platinum and 5.94 weight percent combined chlorine.

The catalyst obtained was tested for the isomerization of n-pentane and η-hexane to isopentane or i2-dimethylbutane. For this purpose, 50 cm ^{3 of} catalyst were arranged in the form of a fixed bed in a tubular reactor. A charge of 50 mole percent n-pentane and 50 mole percent η-hexane, mixed with hydrogen to establish a hydrogen / hydrocarbon molar ratio of 8, was fed at an hourly space flow rate; the liquid of 2.0 passed over the catalyst. The reactor temperature was 140 ° C. and the pressure was 69 atm. The test results are shown in Table I.

As already said, the order of handling is with AlCI. and CCI ₁ essential for success. Treatment with aluminum chloride must precede treatment with carbon tetrachloride. This is illustrated by Comparative Example A below, in which the order was reversed.

Comparative example A.

60 g of CCU were passed over 125 g of the reduced platinum-impregnated aluminum oxide spheres using nitrogen as the carrier gas. The treatment with carbon tetrachloride was carried out in 1.5 hours at 300 ° C. The beads were then rinsed at 300 ⁰ C with nitrogen. Thereafter, 50 g of AlCl _{3 were} evaporated and passed over the spheres using hydrogen as a carrier gas. The ALCH-treatment lasted for 1.5 hours at 55O ⁰ C. The balls were then rinsed for one hour at 600 ⁰ C with hydrogen. The finished catalyst contained 0.4 percent by weight of platinum and 5.71 percent by weight of combined chlorine.

The catalyst was tested in the same manner as in Example 1. The results are in Table I. specified.

The following comparative examples B and C show that the improved activity is not achieved, if the combined chlorine content is only reduced by an AlCl! treatment or only by a CCU treatment is brought about.

Comparative example B

There were 50 g of AICI3 in hydrogen as a carrier gas evaporated and passed over 125 g of the reduced platinum-impregnated aluminum oxide spheres. The aluminum chloride was fed over 1.5 hours at 550 ° C. The balls were then at for an hour 600 ° C flushed with hydrogen. The finished catalyst contained 0.4 percent by weight platinum and 5.56 percent by weight combined chlorine. The test results are given in Table I.

Comparative Example C

44 g of CCU were passed over 130 g of the reduced platinum-impregnated spheres using nitrogen as the carrier gas. The treatment with CCU lasted 1.5 hours at 300 ^° C. The catalyst was then flushed for one hour with nitrogen at 300 ^° C. to remove unreacted CCU. The finished catalyst contained 0.4 percent by weight of platinum and 5.66 percent by weight of combined chlorine. The test results are given in Table I.

Table I.

Conditions for the k; il; il> N; itoipruliini:

^ / Hydrocarbon ratio 8: 1

Hourly Space velocity

the liquid 2.0

Charge 50 mol%

n-pentane
50 mol%
n-hexane
Pressure 69 atm

continuation

example treatment React Product distribution functional AlCIi CCU tempe- i-Cs. i-Cb. rature, ⁰ C % *)% **)

first

second

second first

Yes
no

no
Yes

140
120

140
120
140
140

71
54

68
46
61.5
59

32.5
25.5
29.5
20.5
25.5
23.5

Moles of isopentane
Mole Cs

100.

Moles of 2,2- dimethylbulane
Mole Ce

• 100.

The clear improvement in compliance with the provisions of the invention (example 1) is _{readily apparent from a comparison with the results for i-Cs and iC b} in the comparative experiments (comparative examples A, B, C).

Example 2

There were gamma aluminum oxide balls from 1.6 mm in diameter containing 0.3 percent by weight of combined chlorine with an aqueous solution of Chloroplatinic acid, hydrochloric acid and tin (IV) chloride at a content of 0.6 percent by weight platinum and 0.5 Weight percent tin impregnated. The drying, calcination and halogenation took place as in Example 1. The finished catalyst contained 8.78 percent by weight combined chlorine. The catalyst was tested in the same manner as in Example 1. The test results are given in Table II. In Table II also shows values from Example 1 again for comparison.

Example 3

1.6 mm diameter gamma-alumina spheres containing 0.3% by weight of combined chlorine were impregnated with an aqueous solution of chloroplatinic acid, germanium tetrachloride and hydrochloric acid so that they contained 0.375% by weight of platinum and 0.5% by weight of germanium. This catalyst was then treated and tested as in Example 1. The results are listed in Table II. The catalyst contained 5.53 percent by weight of combined chlorine.

'10

Example 4

There were gamma-alumina spheres 1.6 mm in diameter, the 0.3 percent by weight bound Chlorine and 0.6 percent by weight of tin introduced by coprecipitation contained, with an aqueous Impregnated solution of chloroplatinic acid and hydrochloric acid. The material then contained 0.6 percent by weight Platinum and 0.6 percent by weight tin. It was

ίο then dried, calcined and as in Example 1 halogenated. The finished catalyst contained 6.35 percent by weight combined chlorine. He became like in Example 1 checked. The results are shown in Table 11.

Example 5

A palladium-tin catalyst was made by the usual impregnation of palladium on an aluminum oxide, which was precipitated together with a tin component; the catalyst contained 0.54 Weight percent palladium, 0.5 weight percent tin and 5.25 weight percent chlorine on aluminum oxide. The material was then dried, calcined and halogenated as in Example 1. The test results are in given in Table II.

Table Il

Test conditions exactly as given in Table 1

All catalysts were initially with AICb and then treated with CCU

example 35 1 Promoter React Product distribution i-a. functional ¹¹ Ai 40 y tempe- i-Cs. 32.5 rature.
C. % 25.5 3 - 140 71 35 120 54 32 45 <* Sn 140 76 36 (impregnated) 120 66 32 Ge 140 74.5 35.3 5 120 64 36.8 Sn 140 76 (together ge 120 72 36 falls) Pd-Sn 140 71 (no Pt)

Again it is readily apparent that in all cases excellent and due to the addition of promoter even further improved results can be achieved.

Claims (3)

Patent claims: 1. Catalyst which contains a platinum group metal on an aluminum oxide carrier and bound halogen, which is at least partially obtained by treating the aluminum oxide carrier containing 0.1 to 5 percent by weight of platinum group metal, optionally in a pre-reduced state and / or in a reducing atmosphere, with a Friedel-Crafts Metal halide has been incorporated at a temperature of 100 to 600 ⁰ C up to the introduction of 2 to 15 percent by weight of bound halogen, characterized in that it contains at least 0.1 percent by weight of further bound halogen which it receives after treatment with the Friedel-Crafts Metal halide by treating with a polyhalogen compound from the groups of substances containing at least two halogen atoms on the same carbon or sulfur atom, boron trihalides, trihalogen derivatives of methane and their methyl substitution products, carbon tetrahalides, sulfur dihalides, sulfuryl halides, thionyl halides ogenide, carbonyl halide and thiocarbonyl tetrahalide in a non-reducing atmosphere at 100 to 600 ⁰ C has been incorporated 2. Process for the preparation of a catalyst according to claim 1 by treating an aluminum oxide support containing 0.1 to 5 percent by weight of a platinum group metal, optionally after pre-reduction and / or in a reducing atmosphere, at 100 to 600 ⁰ C with a Friedel-Crafts metal halide up to Introduction of 2 to 15 percent by weight of bound halogen, characterized in that it is then mixed in a non-reducing atmosphere at 100 to 600 ^° C. with a polyhalogen compound from the groups of substances containing at least two halogen atoms on the same carbon or sulfur atom, boron trihalides, trihalogen derivatives of methane and their methyl substitution products, carbon tetrahalides, sulfur dihalides, sulfuryl halides, thionyl halides, carbonyl halides and thiocarbonyl tetrahalides, until at least 0.1 percent by weight of further bound halogen are introduced. 3. Use of the catalyst according to claim 1 or according to the method according to claim 2 prepared catalyst for the conversion, in particular the isomerization, of hydrocarbons.