DE1276265B - Process for the production of saturated aliphatic hydrocarbons containing 1 to 5 carbon atoms together with benzene and homologues by cracking light petrol - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Clog

German class: 23 b -1/04

Number: 1276 265

File number: P 12 76 265.1-44 (St 25686)

Filing date: July 25, 1966

Opening day: August 29, 1968

The invention relates to the production of saturated aliphatic hydrocarbons containing 1 to 5 carbon atoms along with benzene and homologues by cracking light gasoline with a boiling range from 40 to 110 to 180 ° C.

It is well known that the hydrocarbons present in light petrol (bp 40 to 110 to 180 ° C), especially those having 5 to 7 to 9 carbon atoms by thermal cracking at temperatures from 700 to 900 ° C largely into gaseous unsaturated hydrocarbons with 2 to 4 carbon atoms and also essentially converted into methane and hydrogen.

In such a cracking process - calculated according to parts by weight and depending on the composition of the starting material and the respective operating conditions - converted to, for example, 20 to 25% in ethylene and, for example, 35 to 55% in methane, propylene and unsaturated C ₄ hydrocarbons; In addition, 20 to 30% of the liquid hydrocarbons are produced, the so-called cracked gasoline, mostly with a higher aromatic content than the original gasoline.

The generated liquid hydrocarbons have a larger one due to the higher aromatic content Get value as fuel for gasoline engines.

As a starting material for the production of pure aromatics, this liquid fraction is relatively low aromatic content and unsaturated hydrocarbons, however, less suitable.

Of the gaseous products obtained during cracking, ethylene and butadiene have the highest value as starting material for chemical syntheses; the value of the other gases is limited mostly only on that as fuel.

A process is also known (see, for example, British patent specification 935 681) in which, with a view to the production of ethylene and aromatics, light gasoline is first cracked by heating and, in the process, largely converted into methane, ethylene, gaseous unsaturated hydrocarbons with 3 to 4 carbon atoms and a liquid fraction (cracked petrol) pass over, the latter fraction, after the gases have been separated out under certain pressure and relatively mild temperature conditions, then subjected to a catalytic hydrogen treatment in order to saturate the olefins present in the cracked petrol, so that this cracked petrol is suitable for to serve as a starting material for the extractive extraction of aromatics, whereupon the remaining liquid after extraction of the aromatics is used to process saturated,
Aliphatic containing 1 to 5 carbon atoms
Hydrocarbons along with
Benzene and homologues by cracking
Light petrol

Applicant:

Stamicarbon N.V., Heerlen (Netherlands)

Representative:

Dr. F. Zumstein, Dr. E. Assmann,

Dr. R. Koenigsberger

and Dipl.-Phys. R. Holzbauer, patent attorneys,

8000 Munich 2, Bräuhausstr. 4th

Named as inventor:
Gerrit Hovestreydt, Beek;
Johan Diederich Logemann,
Kees Delcour, Geleen (Netherlands)

Claimed priority:

Netherlands of July 26, 1965 (65 09 667)

can be fed back to the thermal cracking process.

Another disadvantage of this process is that the aromatics content of the end obtained cracked gasoline is at least so low that these aromatics by means of extraction, one with a large Cost associated method, must be won.

It is also a method (see e.g. U.S. Patent 2143,472) for the recovery of Aromatics and low-boiling olefins based on a naphthenic oil distillate known, wherein the starting material in vapor form is subjected to such a catalytic treatment that Naphthenes pass into aromatics, after which the reaction mixture undergoes a non-catalytic cracking process is subjected to the paraffins and any naphthenes still present, both of which have a boiling point that goes beyond that of aromatics, to lower-boiling olefins and paraffins to crack, whereupon the reaction mixture by rectification into a tar fraction, an aromatic fraction, Paraffin and olefin fractions and gaseous hydrocarbons is separated. How yourself shows, is used to obtain pure aromatics too

809 598/513

3 4

in this process the aromatics thus obtained on the one hand takes place a catalytic, so-called

fraction subjected to an extraction in order to take on this hydroforming of the gasoline, what an on-way between those in the aromatic fraction still increased the aromatic content caused, e.g. B. as a result of a existing non-aromatics, which do not result in the dehydrogenation of naphthenes with 6 to 8 carbon atoms, solve the extractant, and the actual 5 isomerization of naphthenes with 5 carbon atoms in the Aromatics, which with the extractant form a ring to naphthenes with 6 carbon atoms in the ring Form solution to cause separation. subsequent dehydration with cyclization under

The invention now provides a process for the hydrogen separation of paraffins for preparation saturated, 1 to 5 carbon atoms containing maten, and on the other hand a catalytically hydraulic aliphatic occurs Hydrocarbons, along with io rendes cracking of paraffins to lower saturated benzene and homologues by cracking light hydrocarbons with 1 to 4 carbon atoms. petrol with a boiling range from 40 to 110 to The operating conditions under which the inven-

180 ° C, which is characterized in that the proper hydrogen treatment of the light gasoline in the presence of a hydrogenation dehydrating benzine, differ from those which tion catalyst of a hydrogen treatment and is generally used in the hydroforming of Benter, at which the pressure 15 to 90 at, the tem-ines occur, which ultimately also results in a temperature, at least at the end of the hydrotreating result is obtained.

ment, is 550 to 600 ° C and the molar ratio in hydroforming is an aromatic

Hydrogen gasoline formation at a value of 4 to 20, in particular toluene and xylene formation, and is maintained while the space velocity, 20 an isomerization of the liquid hydrocarbons with which the light gasoline over the catalyst is desired, with hydrogen being released and which conducts is chosen so that the gasoline rninde- process is directed in such a way that at least half of the saturated, gaseous C ₁ - to a few gaseous hydrocarbons are formed. ^ -Hydrocarbons and for the rest of a part in the hydrogen treatment according to the invention

Liquid with an aromatic content of at least 25 d _un g also occurs aromatics formation, in addition at least 70 percent by weight is converted, whereby a large part of the liquid _{non-aromatic remainder consists mainly of saturated C 5} hydrocarbons in gaseous saturated carbons If necessary, the aromatic hydrogens with 1 to 4 carbon atoms are reacted, and the resulting aromatic-containing liquid does not release hydrogen, rather the liquid is obtained by rectification and, if necessary, a little hydrogen decay, the hydrogen treatment in two stages need through, z. B. carries an amount of 0 to 3 weight, wherein in the first stage a Pt catalyst percent, calculated on the amount of used on a support of aluminum oxide with halogen gasoline; All of this is related to the composition of the original gasoline and lyser as a promoter and, in the second stage, a Pt catalyst on a silicon dioxide carrier or the ratio between the aromatics produced on an aluminum oxide carrier with an amount of alkali and the amount of gaseous form Products, or alkaline earth metal is present as a promoter. The greater the formation of gaseous hydrocarbon

The process is also preferably substances, the greater the hydrogen consumption, indicates that the hydrogen treatment can also be used in the aromatic

in the presence of a 0.1 to 2 percent by weight Pt 40 liquid by taking into account a containing catalyst, the support of which is made of aluminum - higher temperature in the hydrogen treatment There is miniumoxide and / or silicon dioxide, through the ratio of benzene to its homologues, in favor of benzene.

The process according to the invention offers the advantages to carry out the desired implementation part, that according to the procedure a liquid fraction 45 reactions one uses the normal trade with so greatly increased aromatic content is formed, conventional dehydrogenation catalysts, i.e. Metalldaß the aromatics from it by a comparison catalysts, such as Cr, Mo, Pt, Pd or other Edelzur Extraction method far cheaper separating pre-metals; the metals are on a carrier gang, namely obtained by rectification are applied.

den can, and on the other hand gaseous saturated 50 Very active platinum catalysts are preferred, Hydrocarbons with essentially 2 to 4 C in which platinum in an amount between 0.1 and Atoms are obtained which are excellent there- 2 percent by weight on a support, essentially to be suitable as a starting material for the production of consisting of aluminum oxide and / or silicon-ethylene by thermal cracking of the carbon dioxide.

Hydrogen to serve, whereby besides ethylene only 55 It is used in the hydrogen treatment for such a small amount of less valuable gaseous temperature and pressure conditions and By-products such as propylene is formed. in addition, such a ratio of hydrogen: gasoline

The method according to the invention also has the advantage that the aromatic content of the liquid has the advantage that the fraction to be obtained will be at least 70 percent by weight, is flexible with respect to products, ie the ^60th fraction mainly consists of C ₅ possibility , by changing the reaction hydrocarbons and, moreover, the conditions more aromatics and less gaseous original starting material, e.g. half or shaped hydrocarbons or less aroma, even more in gaseous saturated C ₁ - to C ₄ coimates and more gaseous hydrocarbons is converted into hydrogen. 65 The pressures required for this can e.g. B. from

In the catalytic water according to the invention 15 to 90 at, preferably from 25 to 60 at, the Substance treatment under pressure essentially plays molar ratios between hydrogen and gasoline two known reactions play a role. vary from 4 to 20 during final temperatures

from ζ. B. 550 to 600 ° C come into consideration; the light gasoline can be used in z. B. a lot of 0.5 to 10 parts by volume in liquid form per part by volume of catalyst per hour passed over the catalyst will.

At the beginning of the hydrogen treatment, the temperature can be lower because even at temperatures of z. B. 450 to 525 ° C aromatics will form for the likewise desired conversion of the majority of the paraffins not to be converted into aromatics to the desired gaseous saturated C ₁ - bis (^ -hydrocarbons but the temperature at the end of the hydrogen treatment must be about 100 to 50 ° C can be increased.

The hydrogen treatment in successive stages, if necessary, is also advantageous with a different type of catalyst in each stage, with temperature in the first stages and pressure are kept at a relatively low level and in the final stages a temperature and Pressure increase is brought about.

The catalyst present in the hydrogen treatment can be in the form of both a flow and a also have those of a fixed bed.

The inventive method has the advantage that a liquid with a high proportion of forms valuable aromatics and these aromatics do not need to be obtained by extraction; on the contrary, a simple, less costly rectification can be used as the separation process content.

Such a separation by distillation can, for. B. consist of a first stage in which a top product from benzene and non-aromatic hydrocarbons as well as a bottom product, which by means of a next rectification in toluene as the top product and a xylene contaminated with ethylbenzene can be broken down as a bottom product.

The mixture obtained as the top product in the first rectification process can be used for recovery of pure benzene in the known manner of an azeotropic distillation, with z. B. acetone as Auxiliary liquid.

The saturated gaseous hydrocarbons obtained during the hydrogen treatment are subjected to a cracking process for the production of ethylene by thermal means. From these gases before the actual cracking process can methane and hydrogen, which do not lead to the formation of ethylene contribute, be eliminated.

In the hydrogen treatment according to the invention, the sulfur compounds do not need to to be removed from the starting material for the most part.

Light petrol with sulfur contents of z. B. 1000 ppm can still be processed. True will the formation of aromatics will be less on the one hand, but on the other hand more will be converted to ethylene form gaseous hydrocarbons.

The method according to the invention is illustrated with reference to FIGS. 1 and 2, in which in a schematic manner Embodiments are shown, explained.

In the embodiment according to FIG. 1, gasoline is fed via line 1 to reactor R, in which the hydrogen treatment is carried out under pressure.

The reaction mixture thus formed enters a separator S ₁ via line 2, where the gases are separated from the liquid fraction after cooling.

The liquid fraction goes via line 3 to a stripping column D ₁ in which still dissolved gases are obtained as top product, while the liquid flows as bottom product through line 4 into a next rectification column D ₂ . In this column, a separation is obtained between benzene and non-aromatic mainly C ₅ ⁺ hydrocarbons on the one hand, which leave via line 6, and the higher-boiling toluene and xylene on the other hand. The mixture of toluene and xylene flows via line S to a rectifying _{column P 3} , from which the top product via line 7 is the toluene and the bottom product via line 8 is xylene, which always contains a little ethylbenzene.

The benzene-paraffin mixture emerging as the top product from column D ₂ can be used to obtain pure benzene in the usual way by means of a distillation with z. B. acetone can be subjected to a further separation as an auxiliary liquid.

The gas mixture of hydrogen and saturated C ₁ to C ₄ hydrocarbons emerging from separator S ₁ enters a separator S ₂ through line 9, in which hydrogen is separated from the hydrocarbons by cooling. If necessary, this hydrogen is brought under pressure again by compressor P and fed back into reactor R.

The hydrocarbons leaving the separator S ₂ or the hydrocarbons obtained as the top product from the distillation column D ₁ go via lines 10 and 11 to the cracking system K ₁ , in which the ethane, propane and butane are subjected to a non-catalytic thermal cracking process with the formation of ethylene ; the resulting reaction mixture flows via line 12 to the gas separation vessel S ₃ .

The ethylene produced is discharged via line 13, while ethane not converted into ethylene enters the ethylene cracking plant K ₂ via line 14; the gas mixture formed during this cracking process is fed back into the gas separation vessel S ₃ via line 16. Residual gases (a mixture of essentially methane, propylene and propane) are removed from the system through discharge lines 15 - only one is shown. If desired, these residual gases can be returned to a heat cracking plant, if necessary after being broken down into components.

The embodiment according to FIG. 2 differs from that according to FIG. 1 in that the hydrogen treatment takes place in several reactors R ₁ and R _{2 connected} in series and that the gas mixture of saturated C ₁ - bis emerging from separator S ₂ and stripping column D _{1 via line 11 takes place} ^ Hydrocarbons are first sent to a gas separator S ₄ for the purpose of removing methane, which relieves the load on the cracking systems. The methane fraction, which still contains components to be cracked into ethylene, then goes through line 18 to gas separator S ₃ ; the C ₂ to C ₄ fraction emerging from the separator S ₄ enters the cracking plant K ₁ via line 17.

The reactor R ₁ can then be loaded with a catalyst better suited for the formation of aromatics

Claims (2)

7 8 be sent, such as Pt on a support of Al ₂ O ₃ , butane fraction (2.9 g). The liquid fraction (34 g) obtained in the hydrogen treatment with a small amount of halogen, if necessary, with (Cl, F) as a promoter, while reactor R ₂ has an aromatic ^{content of 87.6 fl} / o, can be divided into the destructive hydrogenation of the paraffins in: th catalyst, such as Pt on a support of Al ₂ O ₃ 5
with a small amount of alkali metal or alkaline earth metal ⁵ ' ³ & benzene as a promoter, or Pt on a 13.1 g toluene carrier of SiO ₂ can contain. In addition, 11.4 g of xylene and ethylbenzene one the temperature of the reactor A ₂ to a little 4.2 _{g of} non-aromatics, essentially from higher, z. B. a level 50 ° C higher bring 10 saturated C ₅ and a little bit of C ₅ ⁺ than the temperature, which in the reactor R existing hydrocarbons, is to be maintained. Because the hydrogenation reactions are endothermic, in the case of direct thermal cracking of the if the reaction gasoline is supplied by the supply of heat, that is to say without carrying out a hydrogen temperature and the temperature profile in the reactor 15 treatment, one would get: R ₁ can be maintained as required while just in the reactor R ₂ for destructive hydrogenation - ³ ' ⁵ S ethylene the paraffins and olefins heat by cooling 15.5 g methane + hydrogen is to be discharged. 18.5 g propylene + propane The Ausfüh- 20 1 ^ 5 _g ^ -hydrocarbons shown in Figs. Rungsformen are limited to the actual ₂₆ cracked gasoline with an aromatic principle. In practical operation there are, of course, several reactors for hydrogen treatment, which are periodically put out of operation. B. by carbon 25 In a manner similar to that in Example 1, a regenerate. Gasoline with a bp of 40 to 116 ° C processed. It is generally also an addition of water per 100 g of starting gasoline are necessary after the hydrogen, because in the hydrogen treatment 64 g of C ₁ to C ₄ gaseous carbon-hydrogen in proportions of 0 to 3% of the additional hydrogen won. These consist of: amount consumed. The following examples give an impression ■ * · "§ ^" "a _{of the 19 g of C 2} H _{6 obtained} by the process according to the invention aimed results. 24 g of C ₃ H ₈ Example I ³⁵ HgC ₄ H ₁₀ In a device according to FIG. 1 becomes a thermal cracking result from this Gasoline with a boiling range of 40 to 160 ° C, 27.9 g of ethylene and residual gases. The latter consist of first a five-fold amount of hydrogen (calcu- lated. Hydrogen-methane fraction (21.7 g), one net on gram molecules) at a temperature of 40 propylene-propane fraction (10.9 g) and a butylene 565 ° C and a pressure of 30 at over a butane fraction (2.9 g). Aluminum oxide with a platinum coating consists - The resulting after the hydrogen treatment passed the catalyst (0.6 percent by weight Pt, liquid fraction (37 g) with an aromatic 0.66 percent by weight Cl), with a throughput of 89%, can be separated into: Set speed of 11 gasoline per liter of Kata- 45 lysator per hour. ⁹ > ³ 8 benzene After this, 16.9 g of toluene fall per 100 g of the charge mass Hydrogen treatment 68 g C ₁ to C ₄ gaseous 6.7 g xylene + ethylbenzene Hydrocarbons on, namely: ₄₎ 1 _{g of} non-aromatics, essentially off Ils CH ⁵ ° * - * 5 ^{un <} ^ f ^erner Q ⁺ existing """* Hydrocarbons. 20 g C ₂ H ₆ 26 g C ₃ H ₈ with thermal cracking of this gasoline without Hg C ₄ H ₁₀ prior hydrogen treatment would be 55 hold: which amount together with water vapor of a 24 5 e Äthvlen Heat cracking system K _{1 is} fed to there at., / · »,,. "," to be cracked at a temperature of 800 ° C. ¹⁴ § ^Methane + Hydrogen The cracked reaction mixture enters the gas - 20.5 g propylene + propane separator S ₃ , from where an amount of 21.6 g of ethane 60 12 g of C ₄ hydrocarbons via line "of Äthankrackanlage K ₂ to-23 g cracked-gasoline having an aromatics goes to there a new cracking process at a content of 20%. To be subjected to a temperature of 820 ° C. At the end of the day, gas separation includes: 100 g of starting gasoline, 29.2 g of ethylene and a 65 Amount of residual gases. The latter consist of a 1. Process for the production of saturated, 1 to Hydrogen-methane fraction (23.8 g), an aliphatic carbon containing pro 5 carbon atoms pylene propane fraction (11.5 g) and a butylene hydrogen together with benzene and homo- logen by cracking light gasoline with a boiling range from 40 to 110 to 180 ° C, characterized in that the gasoline is subjected to a hydrogen treatment in the presence of a hydrogenation-dehydrogenation catalyst, at which the pressure is 15 to 90 at, the temperature at least at the end the hydrogen treatment is 550 to 600 ° C. and in which the molar ratio of hydrogen to gasoline is kept at a value of 4 to 20, while the space velocity at which the light gasoline is passed over the catalyst is chosen so that the gasoline is at least half is converted into saturated, gaseous C ₁ - bis (^ hydrocarbons and the remainder into a liquid with an aromatic content of at least 70 percent by weight, the remainder mainly consisting of saturated C ₅ hydrocarbons, the aromatics being optionally obtained from the ao Aromatic liquid wins by rectification, and optionally the hydrogen treatment carried out in two stages, with a Pt catalyst on one in the first stage Carrier of aluminum oxide with halogen as promoter and in the second stage a Pt catalyst on a support of silica or a support of alumina with an alkali or Alkaline earth metal is present as a promoter. 2. The method according to claim 1, characterized in that that the hydrotreatment in the presence of 0.1 to 2 percent by weight Pt-containing catalyst, the carrier of which is made of aluminum oxide and / or silicon dioxide exists, performs. Considered publications:
British Patent No. 935,681;
U.S. Patent No. 2143,472. 1 sheet of drawings 809 598/513 8.68 © Bundesdruckerei Berlin