DE1767848B1 - Process for the production of a noble metal alumina catalyst and its use - Google Patents

Description

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The invention relates to a method for the percentage of noble metal no more than 1000 μ of Manufacture of a noble metal-alumina catalyst, the surface are removed, and the catalyst which may also contain alkali oxide, is also reduced. Preferably one leads the in which the alumina is first leached with water, reduction of the catalyst with hydrogen at 300 with an aqueous solution of a noble metal compound from 5 to 500 ° C.

treated, dried and heated to high temperature- The catalyst of the invention is particularly suitable

ren is heated. The invention also relates well to the hydrogenation of paraffins with at most on the use of the noble metal-alumina-cataly- 6 C-atoms.

sators for the dehydration of paraffins. In the method according to the invention are as

It is known to impregnate platinum-alumina catalysts by io noble metals, the metals of group VIII of the peri-drenching of alumina particles under a controlled od system, such as palladium, iridium, rhodium, Conditions in water, subsequent calcination ruthenium, osmium and preferably platinum, too and understanding finally impregnation of the particles.

a compound from the platinum group. The total concentration of the precious metal in the clay

There is no control whatsoever with regard to the type 15 soil carrier is appropriately less than 1 ge and intensity of the impregnation stage. The weight percent and is preferably in the range of Catalyst obtained by the known process - 0.05 to 0.5 percent by weight, gates are in terms of their hydrogenation activity for In the catalyst produced according to the invention

Paraffins in need of improvement. sator is therefore more than 50 percent by weight

Furthermore, a method of making a 20 of the noble metal is no further than 1000μ from the halogen-containing alumina noble metal catalyst removed from the surface of the support. The inside of the knows, when alumina is treated with an acid, contains smaller amounts of noble metal and carrier Washed with water and the clay with a can possibly partially no noble metal Solution of a precious metal is treated. This is included. The precious metal is preferably located at least 50 percent by weight of the ions produced by the acid treatment in an outside area Catalyst placed on the layer of the support, at least 50 and at most can have an adverse effect on catalytic activity. 500 μ, in particular 100 to 200 μ, is thick. This catalyst, too, which is also without special The catalytic efficiency of the according to the

Their measure for a targeted impregnation produced catalyst is improved, is made, has in the hydrogenation of paraffin if it is ensured that the crystal size of the fine in many cases does not have the desired activity. Precious metal is not too big. Furthermore, it is known to produce noble metal catalysts to the crystal size of the noble metal not more than one carrier made of activated carbon, with 100 Å, in particular not more than 30 Å. Likewise, however, the carrier with a noble metal solution is brought into contact with the catalytic effect of the noble metal without the carrier having a large surface area beforehand. Preferably has to be soaked with water. As a result, the noble metal has a surface area of more than 50 m ² / g, regulated impregnation of the noble metal in the, in particular, more than 200 m 2 / g. Carrier difficult. The corresponding known In detail, the catalysts are after

Catalysts also have for many cases not produced in the following way: Alumina, the previously the required hydrogenation activity for the hydrogenation was immersed in water and allowed to drain, tion of paraffins. is in an aqueous solution of a noble metal compound

In the known dehydration of paraffins to dung immersed and preferably in the solution the corresponding monoolefins using for a corresponding time something moved and on one A noble metal catalyst drained on a closing. The mass will then suitable carrier, the efficiency of the De- 45 is dried and calcined in a stream of air, and Hydrogenation reaction through undesirable side reactions - at first slowly and then more vigorously, and is functions, e.g. B. aromatization, diene formation and finally reduced with hydrogen. Cracking, humiliated. It has been suggested that the alumina preferably has a surface in the

These difficulties with the corresponding De range 50 to 200 m ² / g and a pore volume of hydrogenation processes to reduce by 50 0.2 to 0.6 cm ³ Zg kept all over in the water. A time carrier distributed is already suitable. However, this measure did not last 5 to 10 minutes. The water applied to a satisfactory solution of the catalytic is preferably pure, such as. B. distilled water hydrogenation of paraffins. or deionized water. The one used to represent the

Accordingly, the object of the invention is to create noble metal compounds suitable for catalysts a process for the manufacture of a noble metal- those that are soluble in water, such as e.g. B. Alumina catalyst with excellent activity, chloroplatinic acid and dinitrodiaminoplatinum. the in the dehydration of paraffins. aqueous solution of the metal compound should preferably

The solution to this problem in a process wise have such a concentration that the for the production of a noble metal-alumina catalyst- 60 final total concentration of the noble metal in the tors, which may contain alkali metal in the range 0.05 to 1.0 percent by weight. The sound can in which the alumina is first eroded with water in the solution of the noble metal compound leached, held with an aqueous solution of a noble metal for a maximum of a few hours. Compound treated, dried and on high The catalyst is preferably in two stages

Temperatures is heated, consists according to the invention 65 dried. The first stage can be under atmospheric exhaustion in that the alumina with the solution of pressure in a stream of air at a temperature of Bring noble metal compound in contact for as long as 80 to 150 ° C or under reduced pressure that at least 50 weight lower temperatures take place in the finished catalyst. This drying

ORK3INAL P ¹ SPZCTED

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stage can last 1 to 3 hours, after which the last of 0.32 cm ³ / g 5 minutes in distilled water traces of moisture by heating to 300 and then allowed to drain. The tablets were then removed at 500 ° C. for a period of up to 24 hours in an aqueous solution of chlorine. The mass of platinic acid, which contains 5 g of platinum per liter, is then reduced uniformly at 300 to 500 ° C. with hydrogen. 5 submerged. There was 11 solution per kilo of tablets

According to a further feature of the invention used and the tablets were 30 minutes

the catalyst according to the invention is kept in the solution and with gentle stirring

Process for dehydrating paraffins on- then drained. Then the

turned, the catalyst being dried in contact with tablets in a standing tube furnace,

at least one paraffin and hydrogen ίο by being exposed to a stream of air at 120 ° C for 2 hours

is brought. were flowed through. The amount of air was reduced to min-

The paraffin has preferably held at most at least 600 l / h / kg of catalyst. Thereupon

17 carbon atoms, in particular a maximum of 6 carbon atoms. the temperature of the furnace was increased to 450 ° C

In order to achieve high yields in this process and kept at this value for 4 hours

To obtain monoolefins as a product, the air volume should remain unchanged. Then the

drive with a paraffin conversion of at most the oven with nitrogen and the air flow

20%, preferably 5 to 15 ° / c, are operated. by a stream of hydrogen in the same amount

The reaction can be replaced with one in a plant, allowing a reduction for 4 hours at 450 ° C

stationary bed or a fluidized bed took place,

will. 20 The finished catalyst contained 0.37% by weight

Preferably, the process becomes platinum at one percent. Some catalyst tablets were in

temperature in the range of 300 to 550 ° C, especially resin held, ground and polished so that a

370 to 500 ° C. The method can be a planar section through the tablets with an optimal

at negative pressure or at overpressure up to 20 atm., see microscope could be observed. Included

preferably in the range from 1 to 10 atm., it was found that the tablets had a uniform

be guided. dark outer layer with a thickness of 190 μ and

To crack reactions and isomerization of a white interior. With a microanalysis

Platinum could not be found in the carbon skeleton in the paraffin dehydrogenation generator with an electron probe

can be found in the manufacture of the catalyst inside the tablets,

an alkali metal oxide incorporated in a known manner 30 The absence of platinum crystallites with a size

be by z. B. the finished catalyst with a rating of more than about 30 A was used in this catalyst

aqueous solution of an alkali metal compound emulator by X-ray diffraction at stepwise

is impregnated, which during the calcination is the detachment and also due to the high chemisorption

talking oxide yields. The alkali metal can be shown from carbon oxide through the catalyst. the

Sodium, potassium or lithium, and one can 35 the latter measurement also indicated that the platinum

each suitable compound of the alkali metal area of the catalyst was 521 m ² / g platinum,

apply the appropriate for calcination. .

Oxide yields. As examples of such compounds, Example 2

one can use carboxylates, e.g. B. Formates and Acetates, a mixture of n-heptane, hydrogen and and mention nitrates and carbonates. Preferably 40 nitrogen in amounts of 11.5, 15.0 or 12.5MoI /

If the concentration of the alkali metal oxide in the h / kg catalyst is above that according to Example 1

Catalyst passed in the range from 0.01 to 2 per weight per catalyst represented. The catalyst

cent, especially at 0.2 to 0.5 percent by weight. was in a stationary bed in one

Although the tubular reaction vessel produced according to the invention is maintained at 430 ° C,

Catalysts lose their activity only slowly, 45 with the total pressure about 1 atm. fraud. Of the

it may eventually become necessary to analyze it after long-term effluent has been analyzed by gas chromatography

regenerate after use. Such a regenerated, whereby it could be determined that 2% of the

ration can be done in a known manner by z. B. n-heptane converted into C ₀ and lower substances

the catalyst were in controlled contact with one and that 11.7 percent by weight of the n-heptane

oxygen-containing gas or with hydrogen or 50 converted into other ^ -hydrocarbons

is brought to a hydrogen-containing gas mixture. the, of which 84% from the desired heptenes

The olefin formed as the product can consist of the.

not changed by the dehydration process 1 3 Paraffin secreted in a known manner or before

the separation of a further reaction with 55 For comparison, a catalyst was prepared,

be thrown. Such a further reaction can in the case of the alumina prepared according to Example 1

z. B. exist in the dimerization, where the catalytic tablets were used, but the platinum

lysatoren known homogeneous or heterogeneous was evenly distributed in the tablets.

Systems are used. The clay tablets were distilled for 6 minutes.

In the following examples, the production is kept 60 Hertem water at 50 ° C, drained

of the catalyst and a number of dehydrogenation and then 3.5 hours with gentle stirring

method using the according to the invention in a 0.1 weight percent solution of

Catalysts produced explained. Pt (NH ₃ ) _O (NO ₂ ) ₂ in 0.3N ammonium hydroxide solution

. (in water) kept at 50 to 60 ° C. There were

B e 1 s ρ 1 e 1 1 65 8.5 1 platinum solution per kilogram of tablets

ICI clay catalyst tablets were used. The tablets were drained

12-1 with a diameter of 3.175 mm, one and then dried, calcined and according to Example 1

Reduced surface area of 90m ² / g and a pore volume.

Claims (1)

5 6 The tablets contained 0.23 percent by weight of Example 5 Platinum. The sections produced according to Example 1 of this Tablets were found to be uniformly light gray when observed with a catalyst prepared according to Example 1 under an optical microscope. impregnated with an aqueous lithium acetate solution. Microanalysis with an electron probe showed 5. As in Example 1, the catalyst was then dried out and calcined with no unevenness in the platinum content, whereupon the lithium content in different zones of the section. The chemisorption was 0.17 percent by weight. The catalyst was carbon monoxide through the catalyst showed that for the dehydrogenation of n-heptane according to Example 2 the platinum surface area of the catalyst 326 m ² / g platinum used. Analysis of the effluent showed that was. ίο 1.1 percent by weight of the n-heptane in C ₆ - and low This catalyst was used as in Example 2 for the rigere substances and 8.5 percent by weight in other dehydrogenation of n-heptane. Analysis ^ hydrocarbons were converted, of which 88% of the effluent showed that 1.3% by weight consisted of heptenes. n-heptane were converted into products below C ₇ and 11.4 percent by weight in other ^ -hydrocarbons, of which 77% consisted of the desired heptenes. It follows that this A hydrocarbon mixture, in which 96% of catalyst in the dehydrogenation of paraffins η-paraffins in the carbon number range C ₁₄ to C _{17 is} less effective than the catalyst according to passed, was with the catalyst according to Example 1. ao game 1 dehydrated under the conditions of Example 2, but with the temperature 420 ° C Example 4 was. The ones in C ₄ and lighter hydrocarbons "The amount of paraffins converted was only 0.02%, which shows that cracking reactions in very little For comparison, a catalyst was prepared, 25 degrees took place. The aromatic content of the stream, which had a relatively small surface area, was less than 0.1 percent by volume and contained relatively large platinum crystallites. Analysis with a fluorescent indicator. These ana-alumina tablets according to Example 1 were also shown that the content of mono-olefins and kept in water, allowed to drain and diene was 22.6 percent by volume. Then kept in connection for 30 seconds with gentle stirring in an aqueous solution of chloroplatinic acid with the hydrogen requirement in the microhydration. This result indicated that the monoolefin solution contained 24 g of chloroplatinic acid per liter, and the diene fraction essentially composed of monoolefins, 1.31 per kilogram of tablets were used. duration.
The tablets were drained and then 1 minute with gentle stirring in a 20 weight 35 example? percent aqueous solution of hydrazine hydrate held, with 1.3 1 solution per kilogram of the catalyst prepared according to Example 1 was again Tablets were used. The tablets were at 430 ° C under a pressure of 1 atm. from rinsed with water, drained and in a mixture of n-heptane, hydrogen and stick hydrogen stream dried, the temperature 40 flowing through the substance. Keeping the entire feed-in quantity Brought to 300 ° C for 90 minutes and then carried 57 mol / h / kg catalyst, the molar-15 Was held at 500 ° C for hours. ratio of n-heptane to hydrogen to nitrogen The finished catalyst contained 0.29 weight- 1.00: 1.25: 1.08. After 17 hours the percent was platinum. Tablet cuts according to by-heptane conversion were 10%, and the yield of Hepspielli was examined with an optical microscope, 45 times was 84%. 0.23% of the one could be found that the tablets converted a fed heptane into hydrocarbons under C _{7 and a} dark outer layer with a thickness of 190 μ. had a white central zone. In the middle zone After 174 hours of continuous operation, the heptane could only slightly fall through microanalysis with electron probe conversion, namely to no platinum can be found. 50 9.5%, the heptene yield being 87%. The chemisorption of carbon oxide by the catalyst was less than 0.1 at this point, and the platinum surface of fed heptane in hydrocarbons below C ₇ was 10 m ² / g platinum. Another proof that implemented. the crystallite size was large (~ 300 Å), the catalyst was then regenerated by being by X-ray diffraction. 55 with a dilute oxygen-in-nitrogen mixture The dehydrogenation of n-heptane was treated with an and then reduced with hydrogen Turn of this catalyst among the same has been. Thereupon his performance in terms of Conditions carried out as in Example 2, with the dehydrogenation of heptane as described above Deviation that the temperature is slightly higher performance very similar. (435 ° C) and the amount of n-heptane hydrogen 60 or nitrogen slightly smaller (3.20, 3.75 or claims: 3.75 mol / h / kg catalyst). The implementation in C ₆ - and lower compounds was 0.3 weight- 1. Process for the production of a noble metal percent, and the conversion into other C ₇ -carbons-alumina catalyst, which optionally still Hydrogen was 2.6%, of which, however, 88% out of 65 can contain alkali oxide, in which the clay the desired heptenes passed. The dehydration is first leached with water, then with an aqueous treatment was much less effective than when a noble metal compound was dissolved. Example 2. delt, dried and at high temperatures 7 8 is heated, characterized in 2. The method according to claim 1, characterized ge that the alumina is marked with the solution of the noble, that the reduction with hydrogen brings metal connection into contact for so long, is carried out at 300 to 500 ° C, that in the finished catalyst at least 50 Ge 3. Use of the catalyst according to a weight percent of the precious metal no more than 5 of the preceding claims in a 1000 μ are removed from the surface, and they drive to the dehydration of paraffins, preferably Catalyst is also reduced. wise from those with a maximum of 6 carbon atoms. 009 530/277