DE2463420C2 - Process for the preparation of reaction products consisting essentially of aliphatic hydrocarbons - Google Patents

Description

The invention relates to a process for the production of essentially aliphatic hydrocarbons existing reaction products according to the preceding claims.

In US-PS 37 28 408 is the reaction of polar organic compounds with crystalline aluminosilicate zeolites described. Numerous examples illustrate this implementation. An indication of a catalytic Conversion of aliphatic compounds containing heteroatoms to reaction products which essentially include aliphatic compounds, but does not appear in this patent.

The object of the invention is to provide a process for the preparation of essentially aliphatic Hydrocarbons existing reaction products through the catalytic conversion of nitrogen or sulfur-containing aliphatic compounds.

The invention relates to a process for the preparation of essentially aliphatic hydrocarbons existing reaction products through the catalytic conversion of nitrogen or sulfur containing aliphatic compounds, which is characterized in that the reaction is carried out in a Temperature of at least 260 ° C. and pressures of 1 to 208 bar in the presence of a crystalline aluminosilicate zeolite having a silica / alumina ratio of at least 12 and a Constraint Index of Performs 1 to 12 as a catalyst.

It is preferred that the silica / aluminum oxide ratio of the zeolite is at least 30, since the stability of the zeolite crystal structure under severe conditions, for example high temperatures, in particular in the presence of water vapor, increases with an increasing silica / aluminum oxide ratio. In addition, it has been observed that at silica / aluminum oxide ratios above about 30 the zeolites absorb greater amounts of cyclohexane than water than at lower silica / aluminum oxide ratios, that is, they are more hydrophobic. The term “aluminum oxide” used in the expression “ratio silica / aluminum oxide” means lattice aluminum oxide, that is to say tetrahedrally coordinated aluminum oxide, in contrast to cationic and precipitated forms of aluminum. The expression “constraint index” essentially indicates the size of the openings in the pores of the zeolite. In order for a zeolite to be effective within the scope of the invention, it should be capable of free absorption of η-hexane, which means that it should have pore openings larger than about 5.10- ^lo m diameter. On the other hand, zeolites with pore openings considerably larger than 5.10- '° m, for example the faujasites commonly used as cracking catalysts, which are usually given "with pores from 6 to 15.10- ^{| 0} m in diameter", are less suitable. It has been observed that all of the zeolites that are particularly effective have pore openings with a size corresponding to a ring of 10 lattice tetrahedra (S1O4 and Al04). No zeolite with pore openings formed by rings of eight tetrahedra was found to be particularly effective; and although a zeolite was found whose pores were defined by a twelve-membered ring, it is believed that, due to blockage by non-lattice material, the actual size of the openings shown by this zeolite is the same as that shown by an unobstructed 10-membered ring.

To avoid complications from such anomalies and also to take the issue into account draw that the structure of numerous zeolites is not yet known, a functional test was developed, which on the basis of the catalytic behavior in a simple reaction chosen for this purpose distinguishes between zeolites that are effective and zeolites that are not effective. After this test Equal weights of η-hexane and 3-methylpentane are applied continuously over a small sample of about 1 g or less of the catalyst at atmospheric pressure according to the procedure described below guided. A sample of the catalyst in the form of pellets or extrudates will have a particle size of about broken into coarse sand and placed in a glass tube. Before the test, the catalyst is treated with a Airflow treated at 538 ° C for at least 15 minutes. Then the catalyst is flushed with helium and the temperature is set to a value between 288 and 510 ° C for a total conversion between 10

and get 60%. The hydrocarbon mixture is transported at an hourly space velocity of 1, That means 1 volume of hydrocarbon per volume of catalyst per hour, over the catalyst with helium dilution out, so that a molar ratio of helium to total hydrocarbon of 4: 1 is obtained. After 20 minutes, a sample is taken and analyzed, preferably by gas chromatography, to determine the to determine unchanged fractions of the two hydrocarbons.

The "constraint index" is calculated as follows:

". , logio (fraction of remaining n-hexane)

Constraint index -, _{og] o} ( _{fraction of} remaining 3-methylpentane)

The constraint index approaches the ratio of the cracking rate constants of the two hydrocarbon substances. Catalysts suitable for the present invention are those having a Constraint Index from 1.0 to 12.0, preferably 2.0 to 7.0.

It will be understood that the value given in this test is that of a comparison between catalyst performance with one molecule that can be freely absorbed and one that is due to its Side chains cannot be freely absorbed, some information about the sizes of the pore openings Must contain zeolite.

The zeolite is also characterized by the crystal density, it being found that zeolites with a Crystal density of at least 1.6 is particularly effective for producing hydrocarbons in the gasoline boiling range are in the method according to the invention. The crystal density is that of the zeolite in the dry Form of hydrogen, given in grams per cubic centimeter.

The dry density for known structures can be calculated from the number of silicon plus aluminum atoms, as indicated, for example, on page 11 of the publication on the zeolite structure by WM Meier. This literature, the content of which is incorporated by reference, is listed in the Proceedings of the Conference on Molecular Sievens, London, April 1967, Society of Chemical Industry, London, 1968. If the crystal structure is unknown, the crystal lattice density can be determined by the classic pycnometer method. For example, it can be determined by immersing the dry hydrogen form of the zeolite in an organic solvent which is not sorbed by the crystal. It is possible that the unusual long-term activity and stability of this class of zeoites is related to their high anionic crystal lattice density of no less than about 1.6 g per cm ³ . This high density must of course be coupled with a relatively small free space within the crystal, which is why a more stable structure can be expected. However, this free space is important as a location for catalytic activity.

There are a large number of crystalline aluminosilicate zeolites which have the values given above in terms of the silica / alumina ratio and constraint index, and which therefore as Catalysts are effective in the process according to the invention. Some of these, especially the one of course occurring, require a post-synthesis or degradation treatment in order to maintain their silica / Increase aluminum oxide to the prescribed minimum value of 12; however, numerous will be common encountered with silica / alumina ratios considerably higher than 12, for example ZSM-5 usually has a silica / aluminum oxide ratio of 15 to 3000.

The naturally occurring zeolites that can be used include ferrierite, brewsterite, stilbit, Epistilbit, dachiardite, heulandite and clinoptilotite. All of these materials have pore openings that pass through a ring of 10 SiCm and AlCv tetrahedra are intended. The synthetic zeolites comprise the members the ZSM-5 family of zeolites ZSM-12 and ZSM-21 and tetraethylammonium mordenite. The latter owns known pore openings with a ring of 12 SiCv and AICv tetrahedra and it is assumed that one Usability in the method according to the invention caused by an internal pore resistance which the effective size of the pore openings to that of an unobstructed 10-tetrahedral ring decreased. The preferred zeolites are those of the ZSM-5 family, which include the zeolites ZSM-5 and ZSM-II and of this family, the preferred zeolite material is zeolite ZSM-5 itself.

In the case of synthetic zeolites, it is preferred that the silica / alumina ratio be within is in the range of 60 to 600.

As in the case of most catalytic applications of the zeolites, it is advantageous that at least a portion the originally present alkali metal is removed by base exchange. It is preferred that the Alkali ions are replaced by hydrogen ions or by ions such as ammonium ions, which are replaced by thermal treatment can be broken down to hydrogen ions. Many of the above Synthetic zeolites are often obtained in a form that contains a certain proportion of organic stick material cations contains, and in such a case the ratio of those occupied by hydrogen ions becomes cationic sites by thermal treatment as a result of the breakdown of the organic nitrogen cations Hydrogen increased. The combination of exchange and thermal treatment therefore results in these zeolites practically entirely in the hydrogen form, that is, an extremely effective catalytic state.

On the other hand, especially if it is desired ^{to bring the aromatic content of the product at a low process operating temperature, for example 260 to 400 0} C to a maximum value, the zeolite can be with a metal from one or more groups IB, Ha, Hb, HIa, IVa and VIII of the periodic table can be base-exchanged. Zinc and zinc-copper were found to be particularly suitable cations under these circumstances, although cadmium, nickel, and platinum group metals and rare earth metals were also found to be very effective. It can also be implemented by impregnation or a combination of replacement and impregnation. The impregnation can also be carried out with the already completely exchanged zeolite, for example one which is practically completely in the hydrogen form. The amount of metal should preferably not exceed 10% by weight.

It is advantageous in carrying out the method according to the invention to use the zeolite in the form of a mixed material with a material which is catalytically relatively inert. The preferred materials of this type are inorganic oxides, and a particularly preferred material is aluminum oxide. A very good blend material is one that contains 65 wt% zeolite and 35 wt% alumina
The meaning of the “Constraint Index” for some of the zeolites preferably used in the examples is explained below

A simple determination of the cracking rate provides a parameter for the identification of zeolites, which can be used according to the invention. The ratios of the rate constants of the first order from η-hexane to 3-methylpentane for 12 with a mixture of the isomeric hexanes under cracking conditions The catalysts contacted are summarized in Table Ia below.

The ratios given in the last column of the table are divided into three groups. In the first Group (Trials 1 to 5) the ratios are all about 0.50. The inner pores of these catalysts seem equally accessible for the normal and the methyl branched isomers, in the next Group (experiments 6 to 11) the ratios are in the range from 1.0 to about 10, from which it follows that the Pore openings of these zeolites allow the normal isomers to enter the inner pore structure in a distinctive manner Favor the extent, while the 3-methylpentane can still enter the pore system, albeit the access is restricted. The last test at a ratio of 38.0 shows that the structure of the catalyst the 3-methylpentane isomer is not allowed to enter the inner pore system

The conversion of methanol to aromatic hydrocarbons shows a correlation between the • 20 molecular weight of the aromatics formed and the constraint index. Table Ib shows that catalysts with limited access to 3-methylpentane, such as ZSM-5, the production of aromatics in the gasoline boiling range restrict.

Table Ia

First order speed parameters and ratio of

Rate constants

Experiment no. catalyst

REY

HZSM-4

H-mordenite

beta

Si-Al / 46 Al

ZSM-5

ZSM-Il

ZSM-12

ZSM-21

TMA offretit

TEA mordenite

H-erionite

Speed parameter, * ' J-MP * '". R. n-Cf, 0.25 λ'Ί-ΜΙ · 0.11 0.23 0.44 0.12 0.19 0.52 0.10 - 0.53 - 0.10 0.56 0.06 0.11 0.60 0.66 - 6.0 - 0.44 2.2 0.78 0.075 1.8 0.34 0.097 4.5 0.23 0.21 2.4 0.36 0.006 1.7 0.23 38.0

",, _ log. Concentration of the isomer in the feed log. Concentration of the isomer in the product

Table Ib

Distribution of the hydrocarbons obtained from methanol (% by weight)

Coal

material-

number

ZSM-4

Mordenite (H-zeolone)

beta

ZSM-12

ZSM-5

ZSM-II

TEA
Mordenite

ZSM-2

C ₆

C ₇

C ₈

C ₉

Cio

C6-C10-

Cu +

0.2
1.5
3.8
6.9
9.5

1.7 4.5 4.9 4.8 9.6

0.6 12.3 2.1 3.5 5.0 16.4 2.7 16.3 38.8 3.2 14.0 28.3 6.5 26.9 13.0

2.7 1.8 3.5 22.2 11.4 14.6 40.6 53.5 42.5 29.4 22.8 31.6 5.1 10.5 8.0

21.0
78.1

25.5 74.5

16.5 83.5

74.5 25.5

■ 100.0
-0.0

• 100.0
-0.0

-100.0 -0.0

100.0

100.0

100.0

100.0

100.0

100.0

TMA-Offretit and REY, which are given in Table Ia, are not included in Table Ib because they do not form a substantial amount of aromatics from methanol. Since the compulsory index of TMA-Offrelit is six corresponds to other usable materials, however, all converting methanol is to be assumed that at least one further parameter is necessary to a preferred class with regard to the catalyiischen Behavior. Both TMA-Offretit and REY have relatively low ratios of silica

And alumina, both are characterized by a fairly low anionic lattice density. Table Ic

Type of crystal density ₅

Analcime 1.86

Natrolite 1.78

Thomsonite 1.77

Edingtonite 1.67 10

Gmelinite 1.46

Chabezit 1.46

Erionite 1.57

Levynite 1.56

Cancrinite hydrate 1.67 15

Sodalite hydrate 1.72

Phillipsite 1.58

Gismondit 1.53

Barrer PI 1.60

Brewsterite 1.75 20

Heulanite 1.70

Stilbit 1.69

Mordenite 1.72

Dachiarite 1.73

Epistilbit 1.80 25

Ferrierite 1.77

Bikitait 2.02

Faujasite 1.27

Linden A 1.29

ZK-5 1.47 30

Paulinpit 1.55

The anionic lattice density or crystal density for some zeolites of known structure is in Table Ic specified. All of the zeolites used in the following examples had a crystal density greater than 1.6. However, the process can also be carried out when using zeolites which have a lower crystal density leads to be. The preferred zeolites have a Constraint Index in the range 1.0 to 10 and a crystal density ranging from 1.6 to 3.8.

The invention is explained in more detail below with the aid of examples.

B e i s ρ i e 1 1 40

Methyl mercaptan was at a temperature of 288 ° C and a space velocity of 1.4 with a brought into contact crystalline aluminosilicate zeolite A reaction product of the following composition was obtained obtain:

50

65

Aliphatics (wt%) - H ₂ 0 CO 0 CO ₂ 19.53 CH ₄ 3.23 C ₂ H ₆ 1.00 C ₂ H ₄ 33 C ₃ H ₈ 0.65 C ₃ H ₆ 0.23 1C4H10 0.23 nC4H | o 0.23 C ₄ H ₈ 0 C ₄ Ht, Q r "
- ^ j 0 C ₆ 0 C ₇ + 3.9 CH ₃ SH 3.5 (CHa) ₂ p 50.6 H ₂ S 8.4 CS ₂

I. 10 Yy 24 63 420 Example] 2 Aliphatics (wt%) 2.10 I. Aromatics (wt .-%) Tri-n-butylamine was at a temperature of 260 ° C and H ₂ 1.61 E. B. benzene brought crystalline aluminosilicate zeolite into contact. It CO 0.32 1 I. toluene received composition: CO ₂ 0.05 1 I ⁴⁰ Xylenes CH ₄ 0.97 Year ⁵ 20th ArC ₅ C ₂ H ₆ 31.40 1 ArCio C2H4 1.83 Aliphatics. (Wt .-%) C ₃ H ₈ 15.8 45 Aromatics (wt .-%) C ₃ H ₆ 50.6 25th S compounds (% by weight) IC ₄ Hi ₀ H ₂ S (wt .-%) nC ₄ Hio a space velocity of 2.3 with a C ₄ H ₈ was a reaction product of the following composition 50 C ₄ H ₆ C ₅ 30th C ₆ 0.24 55 C ₇ + 0 CH ₃ SH 0 (CH ₃ J ₂ S 0.98 fin H ₂ S 4.38 35 CS ₂ 5.34 Aromatics (wt .-%) 1.54 benzene 17.93 toluene 0.31 Xylenes 1.70 ArC ₅ 39.56 ArQo 4.87 Aliphatics (wt%) 8.78 Aromatics (wt .-%) 3.42 S compounds (% by weight) 2.47 - H ₂ S (wt .-%) - Conversion% - Material. Balance% - 0.59 0.80 1.55 1.44 1.85 93.37 6.63 - - 97.5 97.6 I.

Claims (6)

Patent claims: 1. Process for the production of essentially consisting of aliphatic hydrocarbons' Reaction products by catalytic conversion before nitrogen or sulfur-containing aliphatic products Compounds, characterized in that the reaction is carried out at a temperature of at least 260 ° C and pressures of 1 to 208 bar in the presence of a crystalline aluminosilicate zeolite having a silica / alumina ratio of at least 12 and a Constraint Index of 1 to 12 as Catalyst performs. 2. The method according to claim 1, characterized in that a zeolite with a crystal density, in the dry hydrogen form, of at least 1.6 g per cm ^{3 is} used 3. The method according to claim 1 or 2, characterized in that one at a temperature in the range from 288 to 454 ° C and a pressure in the range from 20 to 196 bar. 4. The method according to any one of claims 1 to 3, characterized in that the crystalline aluminosilicate zeolite a zeolite ZSM-5, zeolite ZSM-11, zeolite ZSM-12, zeolite ZSM-21 or TEA-mordenite a! s Catalyst starts. 5. The method according to any one of claims 1 to 4, characterized in that there is a crystalline Aluminosilicate zeolite with a silica / alumina ratio ranging from 60 to 600 as Catalyst starts 6. The method according to any one of claims 1 to 5, characterized in that a zeolite ZSM-5 with a silica / aluminum oxide ratio in the range from 15 to 3000 is used as the catalyst.