DE1418439C - Process for the hydroisomerization of saturated hydrocarbons - Google Patents

Description

The invention relates to a process for the hydroisomerization of saturated hydrocarbons at elevated temperature and pressure in the presence of a catalyst made from fluorine-containing alumina with 0.01 to 1 percent by weight of platinum and 0.1 to 8 percent by weight of total fluorine and Chlorine. Such catalysts containing alumina as a carrier are known per se.

In the process of US Pat. No. 2,636,863 for reforming gasoline, e.g. B. Catalysts with a content of 0.05 to 8% halogen, preferably 0.05 to 3% fluorine and 0.3 ^w / o platinum. They are produced in such a way that the alumina is prepared by precipitating aluminum hydroxide from aqueous aluminum chloride solution with ammonium hydroxide, washing several times with ammonia-containing water, adding aqueous hydrofluoric acid to the washed aluminum oxide and drying, e.g. B. at 150 ⁰ C, obtained and then combined with platinum sulfate or platinum nitrate. This platinum salt is preferably obtained by first forming platinum sulfide by introducing hydrogen sulfide into chloroplatinic acid and then adding a small amount of aluminum chloride and dissolving the resulting precipitate after washing out the impurities with nitric acid, the excess of which is then removed by further heating. The solution obtained in this way is finally mixed with ammonium hydroxide and combined with the clay formed into tablets, from which the volatile substances are then removed by heating.

Another known gasoline reforming process (U.S. Patent 2,479,110) again uses a supported platinum catalyst is used, the alumina carrier of which is halogen, in particular 0.1 to 3% Fluorine, and has a platinum content of 0.01 to 1 percent by weight. When making the An organic acid, particularly acetic acid, can be added to the carrier, and the platinum is preferred in the form of a chloroplatinic acid solution added to the hydrogen sulfide until a dark brown color was initiated.

While the known processes involve carrying out reforming processes with catalysts made from fluorine-containing alumina and low platinum content, the subject matter of the invention relates to a process for the hydroisomerization of saturated hydrocarbons. In the case of gasoline reforming, the catalyst has a certain isomerization effect, but this is only a part of the entire reforming reaction, which is primarily from dehydrogenation. Dehydrocyclization, hydrogenation and reforming of hydrocarbons consists. In contrast, the invention is based on the object of finding a catalyst particularly suitable for the hydroisomerization of saturated hydrocarbons; it assumes that the known catalysts mentioned are less suitable for this particular purpose.
. The invention therefore relates to a process for the hydroisomerization of saturated hydrocarbons at elevated temperature and pressure in the presence of a catalyst composed of fluorine-containing alumina and 0.01 to 1 percent by weight of platinum with 0.1 to 8 percent by weight of total fluorine and chlorine, which is characterized .

that you have a catalyst with a fluorine content of more than 67 percent by weight, based on the Total halogen content obtained by impregnating calcined alumina with a content of 0.1 to 5 percent by weight bound fluorine with a homogeneous aqueous solution of a water-soluble platinum compound and nitric acid, sulfuric acid, Phosphoric acid, aluminum nitrate, acetic acid, oxalic acid, formic acid or propionic acid, and less

ίο as 2 percent by weight, preferably 0.1 to 1.6 percent by weight, Hydrogen chloride, and which has a pH value below 2.5, preferably below 2, then drying and calcining at 260. bis 595'C is used. Significant

is the predominant fluorine content for this catalyst, based on the total halogen content and the use of a strongly acidic aqueous impregnation solution of a water-soluble platinum compound. It has been shown that the hydroisomerization of saturated hydrocarbons when using a catalyst according to the invention with significantly higher space velocity and lower Temperature can be carried out than when using the known catalysts.

The invention offers the further advantage that the impregnation of the fluorine-containing catalyst support is very high can easily be done with a chloroplatinic acid solution, provided that this has the necessary acid addition having. This solution easily penetrates the alumina carrier and is evenly distributed therein, so that the platinum is distributed in the form of crystallites of very small uniform size throughout the support. The desired high activity is not achieved; when the platinum atoms in part of the support too are closely grouped to one another, whereby the size of the platinum crystallites is increased.

A preferred method of preparing 'clay is to add, for example Ammonium hydroxide or ammonium carbonate to an aluminum salt such as aluminum chloride, aluminum nitrate or aluminum acetate in an amount sufficient to form aluminum hydroxide sufficient. After drying, the precipitated aluminum hydroxide is converted into aluminum oxide.

converted .. Aluminum chloride is generally preferred as the aluminum salt, not just because of the Ease of subsequent washing and filtering, but also because it gives the best results supplies.

After the clay is formed, it is turned into known manner, preferably washed with ammonium hydroxide-containing water to the Bring the chlorine content below 0.1 percent by weight. In any case, this washout is carried out in such a way that that chlorine is retained in the clay only in an amount which is much less than the desired level of bound fluorine. In general, it is convenient to use the clay completely wash out and then chlorine in one

^f) to add 0 separate stage because this enables better control of the amount of chlorine.

The partially dried clay can be mixed with a

Lubricants, e.g. B. stearic acid, resin or graphite, ground and shaped into pills, which in

^ft 5 temperatures of 760 ° C and more are annealed before the addition of platinum. Alumina spheres can be produced by the known dropping method.

ialt) A preferred method for introducing the the bound halogen in the catalyst consists in adding aqueous fluorine or chlorinated water 3e chemical acid. Another suitable source for the no-addition of the halogen is a volatile salt, such as ilen ammonium fluoride or ammonium chloride. The ire, ammonium ions are produced during the subsequent : removed after heating the support or catalyst. ger The bound fluorine content fluctuates in the range of 67 to 100 percent by weight of the total halogen ■ The content of the catalyst depends on the use in question. In general, a catalyst bis Carriers with a fluorine content of 0.1 to 5 percent by weight, especially 0.3 to 5 percent by weight, des :> r vehicle weight used. In a special embodiment, a catalyst with a clay ; n- earth with 0.3 to 5 percent by weight, especially of ig. 2 to 5 percent by weight, bound fluorine and ng less than 0.1 weight percent; preferably less than 0.05 percent by weight of combined chlorine H- he used when soaking with the acidic platinum solution.

Because of its easy accessibility and relatively low cost, chloroplatinic acid is the preferred platinum compound for impregnation. The water-soluble platinum compound is dissolved in an aqueous solution of one of the acids mentioned. Another way of preparing the impregnation solution consists in dissolving the platinum compound in water and adding the selected acidic compound to the solution, if necessary with hydrogen chloride. While fluorine has very strong bonds with t; the alumina enters and is therefore not easily removed from the catalyst support or catalyst during drying and annealing, hydrogen chloride does not lead to the formation of similarly strong bonds η between chlorine and the bound fluorine containing the support. Concentrated solutions of H Chlörwasser- material are not brought into contact with the catalyst support, because they attack the alumina, thereby reduce its surface area available and thus result in fines. If hydrogen chloride is used in the impregnation solution, it is used together with at least one of the following acidic compounds: nitric acid, sulfuric acid, phosphoric acid, aluminum nitrate, formic acid, acetic acid, propionic acid or oxalic acid.

In any case, the composition of the acidic soaking solution is controlled so that it does not enters into substantial reaction with the carrier under the conditions under which the impregnation he follows. Because high concentrations of sulfuric acid, especially at elevated temperatures, with the clay react, sulfuric acid is used in a low concentration and at a temperature where it does not attack the clay.

In general, only a small amount of the acidic compound will be required to adjust the pH of the soaking solution below 2.5, preferably below 2.0. For example, one is Solution of a voigen hydrochloric acid solution with a 1% nitric acid solution for dissolution of chloroplatinic acid and therefore suitable for the preparation of the impregnation solution.

Hydroisomerization converts saturated hydrocarbons, such as straight-chain paraffins or weakly branched paraffins, into hydrocarbons which are used as feed stocks in other petroleum refining processes. The process of the invention can also be used for the hydroisomerization of mixtures of paraffins and naphthenes.

In the hydroisomerization of paraffins, the conversion of less heavily branched paraffins into more branched paraffins occurs. So η-butane is converted into isobutane, n-pentane into isopentane. η-hexane is converted into a mixture of hexane isomers

! o converted from 2-methylpentane. 3-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane. Usually occurs during isomerization a crack on. Due to the presence of hydrogen during the isomerismic reaction are unsaturated hydrocarbons or hydrocarbon fragments that appear as a result of fission are formed, saturated, and "the formation of coke-like deposits on the catalyst becomes thereby reduced to a minimum. The Ver-

drive according to the invention allows the cracking to be regulated so that no excessive amounts Decomposition products are generated and a long catalyst life is achieved and the isomerization process is economically improved. U.N-

regulated cleavage that occurs when many known isomerization catalysts are used to the rapid formation of "large quantities of coke or other high-boiling" hydrocarbon material, that is deposited on the catalyst and its

Activity diminishes or destroys. This in turn results in shorter periods of operation with the need

frequent regeneration or replacement of the catalyst.

The process of the invention is usually carried out under the following reaction conditions: Temperatures from 245 to 480 C, pressures from 6.5 to 100 atm, liquid hourly space velocities (Volume of hydrocarbon, measured as liquid, per hour and per volume of catalyst)

from about 0.5 to about 20. The hydroisomerization process is carried out in the presence of hydrogen, which can be introduced or circulated from an external source. Usually sufficient hydrogen is supplied to its

Balance consumption. The hydrogen present in the reaction zone is within the range from 0.5 to 10 moles of hydrogen per mole of hydrocarbon. The hydrogen-containing gas can be subjected to a treatment to produce hydrogen sulfide

or to remove other contaminants.

The process of the invention can be carried out using the catalyst as a fixed layer, as a Fluidized bed operation in the fluidized state under hindered settling conditions or as fixed

Fluidized bed can be used. The catalyst can also be used in a moving bed process where the Catalyst and the hydrocarbons either countercurrently or cocurrently through a reaction zone or in suspensoid mode

are needed where the catalyst and hydrocarbons pass through the reaction zone as a slurry be directed. The effluent from each of the aforementioned reaction zones usually becomes one further treatment, such as fractionation to remove

separation and recovery of the desired product.

The following examples serve to further illustrate the invention.

example 1

Aluminum pills were dissolved in hydrochloric acid to form a sol containing about 15% aluminum. Sufficient hydrofluoric acid was then added so that the finished mass contained 3.9% fluorine on a dry clay basis. The sol was continuously mixed with hexamethylenetetramine, and dropped into a bath maintained at 90 ⁰ C oil bath. The resulting spheres were Ul and then aged in aqueous ammonia solution and the washed beads with ammonium hydroxide then annealed in a dryer at 250 "C and then dried at 65O ⁰ C.

These balls were soaked in dilute chloroplatinic acid containing 1 percent by weight of HCl and 1 percent by weight nitric acid. The amount of platinum was adjusted so that the finished mass 0.375 weight percent platinum, based on dry

Clay, contained. The impregnated material was calcined at 110 ° C and dried in air at 500 ^u C. It contained 0.05% combined chlorine in addition to a combined fluorine content of 3.9%, based on the weight of the dry clay.

This catalyst was used in the hydroisomerization of n-pentane to isopentane. 50 cm ^{3 of} the catalyst were tested for activity as a fixed layer in a reaction zone. The conditions used were as follows: pressure of 34 atmospheres, a hydrogen to hydrocarbon molar ratio of 2: 1, and different liquid hourly space velocities and temperatures. The results obtained are shown in Table I. The debutanizer overhead and excess recycle gas values are reported in liters of gas under normal conditions per liter of hydrocarbon feed measured as liquid.

table I.
Isomerization of n-pentane with the catalyst of Example 1

1 15 to 18 ³ Vcrsu
4th
Catalytic converter ch no.
5
or 50 cm ³ 6th 7th 8th Use in hours 7 to 10 34
322 23 to 26 31 to 34 39 to 42 47 to 52 60 to 63 75 to 80 Conditions:
Pressure in atm 34.4
301 3.98
2: 1 34
340 34
359 34
380 34
400 34
360 34
360 Temperature in ^l C:
block 3.88
2: 1 0.4
99.6 3.97
2: 1 3.88
2: 1 3.97
2: 1 3.98
2: 1 4.00
2: 1 2.02
2: 1 Liquid space velocity
Ratio of hydrogen
to hydrocarbon 9.3
90.7 0.6
99.4 4.0
96.0 Product distribution in weight
percent:
Ci to Ci 6.7
93.3 100.0 17.4
82.6 39.7
60.3 61.8 '
38.2 60.8
39.2 41.9
58.1 C ₅ 100.0 4.27 100.0 100.0 100.0 100.0 100.0 52.6 Analysis of Cs:
• isopentane 5.52 5.34 7.3 10.1 19.9
1.78 8.02 47.4 n-Pcntan 100.0 Total ·.' 4.09 Dehutanizer package fjrodukt Circulatory excess

9 Table I. (Continuation) Attempt N
12th
Catalyst 5 r.
13th
learn ' 14th 15th 85 to 88 IO Il 121 to 123 126 to 128 131 to 133 142 to 145 Use in hours 34 98 to 103 113 to 118 34 34 34 34 " Conditions:
Pressure in atm 370 34 34 370 390 410 361 Temperature in C:
block 3.94
2: 1 340 370 7.60
1: 1 7.78
2: 1 7.88
2: 1 3.94
2: 1 Fluid space
speed
Ratio of hydrogen
to hydrocarbon ... 2.06
2: I. 1.98
2: I.

ie
: k
: u
ie
d
>
: s
η
I-

continuation

¹⁰ attempt no.
I 12-1, 3
Catalyst 50 cm ³

14th

15th

Product distribution
in percent by weight:

. Ci to Ci

C ₅

Analysis of C.- ,:

Isopentane

n-pentane,

total

Butanizer head product ...
Circulatory excess

51.5

48.5

100.0

8.1

23.1

76.9

100.0

5.87

98.7

56.3

43.7

100.0

0.5
99.5

37.5
62.5
100.0
8.55
2.49

1.3
98.7

57.9
42.1

100.0
11.8
2.31

3.1 96.9

60.3 39.7

100.0 18.3 2.31

41.2 58.8 100.0 6.24 3.03

From Table I it can be seen that an extremely satisfactory conversion of n-pentane to isopentane is achieved by the process of the invention. The temperature required for the equilibrium of transition is markedly lower than the temperatures known for this. After 145 hours of operation, the catalyst contained 0.05 ¹ Vo carbon. This period of time is equivalent to a service life of 14021 hydrocarbon charges per kilogram of catalyst; it was not to determine signs ₀ door a deactivation of the catalyst during the test. It should also be noted that the catalyst used in the process of the invention can be used at space velocities of 4 and 8 while maintaining the equilibrium of conversion. This is impossible with the known catalysts, such as aluminum chloride, for which space velocities of about 0.1 to 0.2 are necessary. This of course means that less catalyst is required in the reaction zone and therefore the economics of the process are considerably more favorable.

e 1 s ρ ι e 1 2

The conditions for testing the stability or life of the catalyst were as follows: Pressure of 34 atm. hourly liquid space velocity of 32nd molar ratio of hydrogen to Hydrocarbon of 2: 1 and temperatures in the range from 445 to 460 C. The results obtained are shown in Table II.

Table II

Durability test of the catalyst during hydroisomerization with n-pentane

Conditions:

Pressure in atm 34

Liquid space velocity 32

Mole ratio of hydrogen to hydrocarbon 2: 1

Temperature in C 445 to 460

60

Hours in liinsnt / Weight Debutanizer
head throttle attempt
No. percent
IsO-C ₅ im 70 to 75 Gesanit-Cj 9.55 ■ 16 89 to 94 53.9 17.45 17th 99 to 103 56.8 15.1 18th 143 to 148 55.8 13.35 19th 193 to 198 56.9 13.35 '20 238 to 243 .55.9 12.5 ' 21 283 to 288 56.7 13.2 22nd 419 to 424 57.0 14.2 23 464 to 469 54.8 14.6 24 524 to 529 55.7 15.5 ■ 25 554 to 559 56.6 15.65 26th 54.5

Used catalyst:
carbon
Top section.
Bottom section

0.99 percent by weight 1.07 percent by weight

It can be seen from these values that the catalyst had constant or stable activity for up to 560 hours of use. The conversion of n-pentane to isopentane was kept at about 55 to 56 ¹ Vo isopentane in the entire G> product. The debutanizer head gas from the pilot plant was fairly steady at a value of 13.3 to 161 per liter of liquid hydrocarbon feed, a substantial proportion (about 5.35! Per liter) of which consisted of hydrogen. This total is essential as it shows that cleavage did not increase with time as the catalyst aged. At the bottom of Table II are the numbers for the carbon content of the catalyst used for this experiment. They show that the catalyst contained about 1% carbon at the end of the run, although it had practically the same activity as originally. The catalyst demonstrated the extraordinarily long service life of over 35 0501 liquid hydrocarbon feed per kilogram of catalyst.

009 636/150

Comparative experiment

The hydroisomerization of n-pentane was carried out in the presence of two catalysts, of which one according to example 1 and the other according to the example in columns 6 and 7 of the LJSA.-

U.S. Patent 2,636,863 was made; the comparison tests were carried out in accordance with Example 2 in three individual experiments each. The following results were obtained:

Catalyst according to the invention catalyst according to the
USA.-PatenlschnTt 2 636 863

Pressure in atm

Temperature in ⁰ C

Space velocity

% Isopentane in the Cs product

34

380

60.3

j; - 3-4.

^! · 450
32
56

34
426
0.5
61

34

450

52

34
470
6th
8.5

Of particular note is a comparison between the at 38O ⁰ C with the catalyst according to the invention and the process carried out at 426 ° C with the known catalyst attempt. It can be seen from this that in the case of the catalyst according to the invention it was possible to use an eight times greater space velocity at a ^{temperature lower by 46 °} C. in order to achieve an even higher isomerization. When using higher temperatures and higher space velocities, the yield drops very sharply when using the known catalyst, while it drops relatively little with the catalyst according to the invention.

Claims (1)

Claim: Process for the hydroisomerization of saturated hydrocarbons at elevated temperature and elevated pressure in the presence of a catalyst composed of fluorine-containing alumina and 0.01 up to 1 weight percent platinum with 0.1 to 8 weight percent total fluorine and chlorine content, characterized in that one a catalyst with a fluorine content of more than 67 percent by weight, based on the Total halogen content obtained by impregnating calcined alumina with a content of 0.1 to 5 percent by weight of bound fluorine with a homogeneous aqueous solution of a water-soluble one Platinum compound and nitric acid, sulfuric acid, phosphoric acid, aluminum nitrate, Acetic acid, oxalic acid, formic acid or. Propionic acid, and less than 2 percent by weight, preferably 0.1 to 1.6 percent by weight, hydrogen chloride, and which has a pH value below 2.5, preferably below 2, then dried and annealed at 260 to 595 ° C has been used.