DE2344564C2 - Process for the preparation of aromatic hydrocarbons from C 2 to C 4 paraffins - Google Patents

Description

The invention relates to a process for the production of aromatic hydrocarbons from Cr to Q paraffins> -Oleefins or their mixtures, at pressures of approx. 1 to 71 bar, in the presence of ion-exchanged Zeolites as a catalyst and a hydrogen to hydrocarbon ratio of 0 to 20.

It has long been known to use various hydrocarbon fractions generally with acidic catalysts and especially with solid siliceous acidic catalysts including those called crystalline ones Aluminosilicate zeolites are referred to. The contact of the hydrocarbon feed The acidic catalysts have been used for a wide variety of reactions including Cracking, isomerization, hydrocracking and the like. Contacting various hydrocarbon fractions with crystalline aluminosilicates is in J5 U.S. Patents 31 40 249.31 40 251.31 40 253 and 31 40 322 and DE-OS 15 18 745 described.

The contact of paraffinic feedstocks with crystalline aluminosilicate zeolites is also known and is by far the predominant cause of the Contacting paraffinic materials with zeolites was for the purpose of cracking; H. their conversion into products of lower molecular weight. A typical application in this general area is the use of crystalline aluminosilicate zeolites to carry out dewaxing reactions; H. the cracking of paraffins into materials low molecular weight

In US-PS 34 00 072 a dewaxing process with crystalline aluminosilicates is generally so wrote.

The formation of aromatic compounds from low molecular weight paraffins is known, however These prior art processes always require the presence of a strong hydride / dehydrogenation component. Processes of this type are disclosed in U.S. Patents 32 96 324 and 33 74 281.

DE-OS 15 18 745 relates to the use of crystalline zeolitic Melallaluminiumsiiicaten as Catalysts for aromatizing hydrocarbons. As can be seen, however, according to this Reference uses a zeolite X as a catalyst, which differs from that according to the present invention used zeolite materials differs significantly. From the comparative experiment brought later, in which, on the one hand, an exchanged zeolite X and a zeolite ZSM-5 were used, the result is that much better conversions and yields Aromatics are obtained when the invention used zeolite of the type ZSM-5 is used,

The object of the invention is to create a process for converting hydrocarbons, those consisting essentially of Cj-Ct paraffins, olefins and their mixtures exist, to aromatic compounds,

This object is achieved according to the invention by creating a process for the production of aromatic hydrocarbons from Cr to CV paraffins, olefins or mixtures thereof, at pressures of about 1 to 71 bar, in the presence of ion-exchanged zeolites as a catalyst and a ratio of hydrogen to hydrocarbons of 0 to 20, which is characterized in that one carries out the reaction at 300-650 ⁰ C and as zeolite a zeolite of type ZSM-5 used which contains, if appropriate, a hydrogenation / DehvG / ier component

According to the invention, aromatic compounds are formed by essentially consisting of C2-C4 paraffins, olefins or mixtures thereof existing feed stream is contacted with a crystalline aluminosilicate zeolite which

i) has a silica to alumina ratio greater than 15;

ii) has been crystallized from a solution containing organic cations so that it is direct contains organic cations after manufacture and

iii) has a pore size such that it sorbs methyl paraffins under the conditions used,

being these conditions

a) a temperature of 300 to 650 ⁰ C,

b) a pressure of approx. 1 to 71 bar,

c) a WHSV value of 0.5 to 400, and

d) comprise a hydrogen to hydrocarbon ratio of 0-20.

It appears that a new reaction mechanism is emerging, since for the first time it is not necessary to have one To use hydrogenation / dehydrogenation component in conjunction with the crystalline aluminosilicate zeolite.

The new process of the invention is very economical because the catalysts used are among the The reaction conditions used are surprisingly stable, so that they are active over long periods of time remain, eliminating the need for frequent regeneration. As can be seen, there was one general characteristic of all previous acidic catalysts, whether amorphous or crystalline, in that they aged rapidly in the absence of a hydrogenation / dehydrogenation component. The invention provides in contrast, a process for the direct conversion of C2-C4 paraffins or olefins into aromatics, the can be operated over long periods of time without adverse effects on the catalyst efficiency or the product selectivity.

As ZSM-5 type zeolites, ZSM-5 zeolites are according to US-PS 37 02 886, ZSM-8 zeolites according to DE-OS 20 49 755 and ZSM-11 zeolites according to US-PS 37 09 979 can be used.

In the zeolites used according to the invention are usually the associated original cations by a wide variety of other cations

replaced according to known techniques Typical replacement cations include hydrogen, ammonium, and Metal cations including their mixtures, cations of hydrogen, Ammonium, rare earths and their mixtures are particularly preferred

Typical ion exchange techniques consist of the special zeolite with a salt of the desired Contact replacement cations or the desired replacement cations. Although a wide variety of salts ι ο can be used, chlorides, nitrates and sulfates are particularly preferred

Typical ion exchange techniques are described in a wide variety of patents including the US Pat U.S. Patents 31 40 249, 31 40 251 and 31 40 253 are described.

After contacting the salt solution of the desired displacement cation, the zeolites can washed with water and dried at a temperature in the range from 65 to about 316 ° C and then in La! t or another inert gas at temperatures in the range from 260 to 816 ° C heated for a period of time ranging from 1 to 48 hours or more.

It is also possible to steam the zeolite at elevated temperatures in the range of 427 to 87 Γ C and preferably 538 to 816 ° C if so desired. Treatment can be in atmospheres which consist partially or entirely of water vapor.

A similar treatment can be carried out at lower temperatures and elevated pressures, for example at 177 to 37 ° C. at about 200 bar.

One embodiment of the invention consists in the Use of a porous matrix, together with the previously described zeolite of the 2. ίΜ-5 type. Of the ZSM-5 type zeolite may be combined with a porous matrix in such amounts or dispersed in be intimately mixed otherwise that the product obtained 1 to 95 wt .-% and preferably 50 to Contains 80% by weight of the zeolite in the finished mass

The term "porous matrix" includes inorganic masses with which the aluminosilicates combine dispersed or intimately mixed in some other way, in which the matrix can be active or inactive can. It should be noted that the porosity of the masses used as a matrix may either be inherent in the particular material or may be through mechanical or chemical means can be introduced. Typical matrices that can be used include Metals and their alloys, sintered metals and sintered glass, asbestos, silicon carbide aggregates, pumice, Fireclay brick, diatomaceous earth and inorganic oxides. Inorganic masses, especially one Silica in nature, are preferred. In particular, these matrices are inorganic Oxides, such as clay, chemically treated clay, silica, or silica-alumina because of their superior porosity, abrasion resistance and stability preferred.

The association of the aluminosilicate with an inorganic oxide can be achieved by various methods, wherein the aluminosilicates on a Particle size of less than 40μπι, preferred less than ΙΟμπι, be reduced and with a inorganic oxide are intimately mixed while h> the latter in a water-containing state, for example in the form of a hydrosol, hydrogel, more humid gelatinous precipitation or in a dry state or a mixture thereof. Thus, fine divided aluminosilicates directly with a silicic acid gel, aas by hydrolyzing a basic one Solution of an alkali metal silicate with an acid such as hydrochloric acid, sulfuric acid or acetic acid formed. That Mixing of the three components can be done in any way, for example in one Ball mill or other types of mills. Lie aluminosilicates can also be dispersed in a hydrosol obtained by reacting an alkali silicate with an acidic or alkaline coagulant became. The hydrosol is then allowed to solidify in the mass to form a hydrogel, which is then dried and broken into pieces of the desired shape is dried or by conventional spray drying techniques or through a nozzle in an oil bath or a Bath of other, water-immiscible suspending medium is dispersed, being spherical shaped bead particles of the catalyst as described in US Pat. No. 2,384,946 can be obtained. That so The resulting silicic acid-containing aluminosilicate silica gel is washed free of soluble salts and then dried and / or optionally calcined

Similarly, an alumina-containing oxide can be incorporated into the aluminosilicates. Such Gels and hydrous oxides are known and can, for example, by adding ammonium hydroxide, Ammonium carbonate and the like to an aluminum salt, such as aluminum chloride, aluminum sulfate, aluminum nitrate and the like in a sufficient amount to form aluminum hydroxide, which is converted into aluminum oxide after drying. In the aluminosilicate that can Alumina-containing oxide are incorporated, while the latter in the form of a hydrosol, hydrogel or one gelatinous precipitate or a hydrous oxide or in the dried state

The catalytically active matrix made of inorganic Oxide can also consist of a multiple gel containing a predominant amount of silica one or more metals or their oxides of groups IB, II, III, IV, V, VI, VH and VIII des Periodic table. Multiple gels or silicon dioxide with metal oxides are particularly preferred of groups HA, III and IVa of the periodic table, especially those in which the metal oxide is an oxide the rare earths, magnesium oxide, aluminum oxide, zirconium oxide, titanium dioxide, beryllium oxide, thorium oxide or a combination thereof. The production multiple gels are known and generally consist of either separate precipitation or simultaneous precipitation processes in which a suitable salt of the metal oxide to an alkali silicate is added and, as required, an acid or base is added to precipitate the corresponding oxide. The silica content of the here into consideration Coming silica-containing gel matrix is generally in the range from 55 to 100% by weight, with the metal oxide content ranges from 0 to 45%.

The inorganic oxide can also consist of raw clay or a clay mineral that has been treated with an acidic medium to make it active. The aluminosilicate can be incorporated into the clay in a simple manner by mixing the two and forming the mixture into the desired shapes. Suitable clays include attapulgite, kaolin, sepiolite, polygarskite, kaolinite, hallosite, plastic

see spherical clays, bentonite, montmorillonite, lllit or Chlorite

Other suitable matrices include refractory oxide powders such as alumina or -aluminium oxide with very low internal pore volume, preferably these materials have practically no inherent catalytic efficacy by itself

The catalyst product can be stored in steam or other atmospheres, e.g. B. air, can be heated close to the temperature intended to be converted, but can also be heated to initial operating temperatures during the application of the conversion process. In general, the catalyst is dried at about 65 to 316 "C and can then in air, steam, nitrogen, helium, flue gas or other gases not harmful to the catalyst product at temperatures in the range of about 260 to 870 ⁰ C for a period of 1 It should also be noted that the aluminosilicate may be calcined prior to incorporation into the inorganic oxide, and it should also be understood that the aluminosilicate or aluminosilicates are not ion exchanged prior to incorporation into a matrix must, but can be treated in this way during or after incorporation into a matrix.

The new process of the invention is carried out in a threading manner by adding a feed stream consisting essentially of C2 — Cr paraffins and / or olefins (ethane, propane, butane, isobutane, ethylene, propylene, butene, isobutene and mixtures thereof) with a zeolite type defined above is contacted at a temperature of about 100 to 700 ⁰ C and the aromatic compounds produced are obtained. The reaction can be carried out at atmospheric pressure and in the absence of hydrogen. The aromatic compounds produced are predominantly Ce-Cio aromatics.

It should be pointed out, however, that it is not necessary to add a hydrogenation-to-hydrogenation component use, and it is not necessary to carry out the reaction in the presence of added hydrogen, although both of these features can be applied if desired. But be on it pointed out that the preferred embodiment of the Invention in carrying out the process in the absence of hydrogen and in the absence of one There is hydrogenation component

When a hydrogenation / dehydrogenation component is used it need not be a strong hydrogenation component, but can be any commonly known Be hydrogenation component. About these components include metals, oxides and sulfides of metals that belong to group VIB including chromium, molybdenum, Tungsten and the like, group HB including zinc and cadmium, group VIIB including Manganese and Rhenium and Group VIII including cobalt, nickel, platinum, palladium, ruthenium and Rhodium and combinations of metals, sulphides and oxides of metals of the Giuppe. VIB and VIII des periodic system, such as nickel-tungsten-su'üd, Cobalt oxide molybdenum oxide fall.

Preferred working conditions when carrying out the process according to the invention are temperatures from 400 to 650 ⁰ C ₁ atmospheric pressure to 22 bar, absence of hydrogen and WHSV values from 0.5 to 400.

The following examples illustrate how the Invention.

Examples 1 to 4

Examples 1 to 4 explain the production of C6 ₊ aromatics by contacting propylene at different temperatures with a catalyst composition composed of 80 parts by weight of H-ZSM-5 (produced by the method according to Example 5 of British Patent 13 23 7 ) 0) and 20 parts by weight of aluminum oxide. The catalyst mass contained no hydrogenation / dehydrogenation component and no additional hydrogen was used. All experiments were carried out at atmospheric pressure.

Further process conditions and results are given in Table 1.

Table I. Propylene 7.72 g 300 400 500 feed 3.9 WHSV value 200 96 96 95 Temperature (° C) 61 52 55 Product recovery (Gcw .-%) 99 Total product (-196 °) 59 35.5 12.5 2.8 liquid product (0 °) 1.1 2.0 10.4 Product yield (g / 100 C ₃ H ₆ ) 44.0 6.3 23.3 35.9 P + O + N 2.9 6.0 9.2 4.0 C ₆ aromatics 3.5 12.5 4.5 2.1 C ₇ aromatics 3.8 61 52 55 C _g format 5.1 26th 39 52 Cg aromatics 59 4th 8th 17th liquid product 15th 30th 47 69 Qi aromatics 31 C ₂ -C 4 olefins 46 Aromatics and olefin

Example 5

This example explains the possibility of using it additional weak hydrogenation / dehydrogenation components.

In this example, the catalyst used was one with ammonium and zinc as the hydrogenation / dehydrogenation component exchanged ZSM-5 catalyst (Zn / HZSM-5, prepared according to example 7 of the British Patent 13 23 710). The reaction was carried out at 500 ° C. in the absence of added hydrogen and at atmospheric pressure.

The results are given in Table II.

Table Il

Propane (g)

Total condensed product (g)

Total liquid product (g)
GLC analysis (wt .-%)

Paraffins and olefins

Q aromatics

C ₇ aromatics

C ₈ aromatics

Cs aromatics
C ₆ -C ₉ aromatics (g)
Wt% of the charge

Heavy gas
Weight (g)

Analysis M.S.

C _: -C ₄ olefins (% by weight)

Paraffins (wt .-%)
C _; -C ₄ olefins (g)
Wt% of the charge

Olefins plus aromatics
Wt% of the charge

Comparison attempt

Conversions were carried out at atmospheric pressure with a ZSM-5 zeolite to be used in accordance with the invention in comparison to an exchanged ZSM-X zeolite according to DE-OS 15 18 745 in Glass reactors carried out, the conditions given in the table below being observed became. The results obtained are also shown in Tables III to V below.

3.4
1,877

0.347 - "'

0.9
48.6
39.6 - '"'

7.1

2.5

0.348 K) '"

¹ , 53

12th
87
0.184

15th

Table III

Conversion of η-butane, 450 ° C, 0.5 WHSV

Operational Na-Zeolite X

HZSM-5

duration in min

Conversion- Aromalen- Conversion- Aromatics Uew .-%

bulge% by weight

lung oew .-%

yield% by weight

5.1 3.6 2.7 1.1 0.8

0.0

0.0 left 0.0 0.0

97 97 97 97

17 17 17 18

Table IV

Conversion of 1-butene, 350 ° C. 0.5 WHSV

HZSM-5

Conversion aromatics Conversion aromatics *) yield yield

% By weight% by weight *,;,% by weight by weight ",

Operating Na-Zeolite X duration in

32

0.0 0.0

95

93

32 33

·) To products other than butenes.

Table V

Conversion of 1-butene. 35O ° C, 0.5 WHSV

Operating Ca zeolite X HZSM-5 Aromatic duration in Conversion Aromatic Conversion yield mm lung *) yield lung Wt% Wt% Wt% Wt%

20 14 12

0.2 0.1 0.1

96 95 93

28 32 33

*) For products other than butenes.

Claims (1)

Claim; Process for the production of aromatic hydrocarbons from Cr bis (^ -paraffins, -olefins or mixtures thereof, at pressures of approx. 1 to 71 bar, in the presence of ion-exchanged zeolites as a catalyst and a ratio of hydrogen to hydrocarbons of 0 to 20, characterized that one carries out the reaction at 300-650 ⁰ C and as zeolite a zeolite of type ZSM-5 used, which optionally contains a hydrogenation component ZDehydrier 15th