AU640814B2 - Process for the aromatization of hydrocarbons containing 5 to 9 carbon atoms per molecule in the presence of a particular catalyst - Google Patents

Description

AUSTRAL

Patents Act 1990

U

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT 0ee Invention Title: be *c S *Ge S. *e S C

S

C 6 4r Ge PROCESS FOR THE AROMATIZATION OF HYDROCARBONS CONTAINING 5 TO 9 CARBON ATOMS PER MOLECULE IN THE PRESENCE OF A PARTICULAR CATALYST.

The following statement is a full description of this invention, including the best method of performing it known to me:- O OO

B

C e C The present invention relates to a process for the aromatization of Ihydrocarbons containing between 5 and 9 carbon ataoms per molecule in the presence of a coiposite catalyst incorporating a MFI structure zeolite containing silicon, aluminium and at least one metal fzrom the platinum fanily, to which are added at least one additional metal chosen from within the group constituted by tin, genrmanium, Ga indium and lead. An amorphous matrix can be added to the catalyst &sea for the shaping thereof.

**000.

a 00 o 10 Catalysts based on zeolites doped with gallium, zinc and platinum G are kncwn to be active and selective in the aromatization of propane and butane. Conventionally hydrocarbons with more than 6 carbon atoms per molecule are transformed into aromatics by catalytic "*^reforming using catalysts of the platinum-doped acid alumina type platinum 15 -to which can be added tin, rhenium, etc. However, these refor- V ming catalysts do not have good performance characteristics for the aranatization of hydrocarbons with 5 carbon atoms per molecule and to a lesser extent for those with 6 carbon atoms per molecule.

0° Thus, there is considerable interest in finding high performance catalysts for the aromatization of hydrocarbon-rich fractions of the

C

5

-C

6 type.

The arnmatization reaction of hydrocarbons with more than 5 carbon atoms per molecule in the presence of zeolitic catalysts has already formed the subject matter of several patents and publications.

-2- Several MFI zeolite-based catalytic systems are claimed and these systems can be distinguished by the additives contained therein. A distinction can be made between: i) systems containing galliun Berti, J. Moore, L. Salusinszki, D. Seddon, Aust. J. Chem., 42, p 2095, 1989) ii) systems containing zinc Anunziata, 0. Orio, L. Pierella, M. Aguirre, React. kin. Catal. Lett., 39(1), 75, 1989; J. Kanai, 4 N. Kawata, J. Catal., 114, 284, 1988).

,e 10 However, all these systems suffer from an inportant defect, namely a high methane selectivity. In order to improve the performance characteristics of these catalytic systems a number of solutions have been proposed, such as the addition of platinum Jin, Y. Makino, A. Miyamoto, T. Inui, Chem. Express, 2 p 515, 1987). The 4 15 use of a non-acid MFI zeolite with various metallic elements has Ve A'S. ealso been claimed Chen. et al. WD 8904818).

Moreover, in French patent application 90/06557, the Applicant claims ;a a catalyst incorporating on the one hand a MFI zeolite and on the other a generally anorphous matrix or support, on which is deposited a noble metal from the platinum group and at least one additional metal chosen fromn within the group constituted by tin, germanium, indium and lead, said support also containing at least one alkali metal and at least one alkaline earth metal chosen from within the group constituted by lithium, sodium, potassium, rubidium, cesium, barium, calcium, beryllium, magnesium and strontium. This catalyst 3 is used for the arcmatization of hydrocarbons with 2 to 4 carbon atoms per molecule.

It has been found that the fixing of the noble metal from the platinumn family (hydrogenating metal) and the additional metal chosen fromn the group constituted by tin, germanium, indium and lead, directly to the zeolite, using methods such as impregnation, exchange or any other known method have led to an inprovenent of the catalytic performance characteristics in the aramatizaticn of hydrocarbons with 5 to 9 carbon atoms per molecule.

ee 4* The MFI structure zeolite of said catalyst (which is preferably acid) used in the present invention can be prepared by all known methods.

The synthesis of said MFI zeolite can be carried out in a conven- 15 tional OH medium, in the presence or absence of organic structuring agents and/or alcohol. The synthesis of the MFI zeolite in the OH medium according to known methods is described in: Synthesis of High Silica Zeolites, P Jacobs and J. Martens, Studies in Surface Science and Catalysis, volume 33, Elsevier Editor, 1987. The MFI zeolite can also be synthesized in less conventional media, such as e.g. the fluoride medium (of. cur European patent EP-A-172068).

After synthesis, the MFI zeolite is transformed into a hydrogen form by the total or partial elimination of organic compounds and/or alkali metal or alkaline earth cations contained therein, possibly -4after synthesis. All known methods can be used for passing to the hydrogen form, such as e.g. calcination in an oxidizing or nonoxidizing atmosphere, ion exchanges followed or not by calcination, various chemical treatments, etc.

All MFI zeolites synthesized in the Si-Al system are suitable for the present invention. However, their Si/Al atomic ratio is genersets **so ally higher than 7, preferably higher than 25 and more particularly 6-toa: between 40 and 1,000.

b.

to o ::The hydrogenating metal is then deposited on the MFI zeolite. Any metal from group VIII of the periodic classification of elements can be used, but platinum is preferred.

4@eee.

4 a 0 0 The platinum can be introduced in different ways, e.g. in the form of a tetrammine complex by cationic exchange, or in the form of a hexachlorcplatinic acid by impregnation.

The platinum (or optionally another noble metal fran the platinun group) can consequently be incorporated into the zeolite by Ipregnating the latter with the aid of an adequate aqueous or nnaqueous solution containing a salt or a caround of the noble metal.

The platinum is generally introduced into the zeolite In the form of chloroplatinic acid, but it is also possible to use compouxnds such as aunonium chloroplatinate, dicarbonyl platinum dichloride, *0g hexahydrplatinic acid, palladiumn chloride and palladium nitrate.

10 AmIng the capounds of the metal or metals fron the platinumn group used in the present invention, reference is also made in exerplitied manner to aroniium conplexes.

In the case of platinum, particular reference is made to platinum 15 IV hexaarmine salts of formula (Pt()NH 6

)X

4 in which X is a halogen atom chosen fron within the group formed by fluorine, chlorine, branine and iodine and preferably X is a chlorine atom, platinum IV t: halcpentaunine salts of formula (PtX(N 3 5

)X

3 platinum IV tetrahalodianrnines salts of formula Pt X4 (N 3 2 in which X has the meaning given hereinbefore, canplexes of platinum with halogenspolyketaces and polyketcne halogen corpounds of formula H(Pt(aca) 2

X)

in which X has the meaning given hereinbefore and aca represents the radical of formula C 5

H

7 0 2 derived from acetyl acetone.

The noble metal fron the platinum fanily is preferably introduced -6by imrpregnation with the aid of an aqueous or organic solution of one of the aforementioned organcmetallic carpounds. Among the organic solvents which can be used reference is made to paraffin, naphthene or arnomatic hydrocarbons and halogen-containing organic crpcunds e.g. having 1 to 12 carbon atoms in their molecule.

Particular reference is made to n-heptane, methyl cycldhexane, toluene and chloroform and mixtures of these solvents can also be used.

10 The element (or additional metal M) chosen fron within the group .constituted by tin, germanium, lead and indium can be introduced via compounds such as e.g. tin nitrate, brcmides and chlorides, 9 .9..halides, lead carbonate, acetate and nitrate, germaniun coalate and *e chloride, indium chloride and nitrate.

The additional metal M can be introduced before or after the introduction of the noble metal. If it is introduced before the noble metal, the caqound used is chosen fran the grcup constituted by halides, nitrates, acetates, carbonates and cocalates of the additional metal. Introduction advantageously takes place in aqueous e solution. In this case, before introducing the noble metal, calcining takes place in air at a temperature between 400 and 1000*C.

The additional metal M can be introduced after the introduction of the noble metal in the form of at least one organic campound chosen -7fran the grap ocnstituted by ccnplexes of metals M and in particular pQlyketone complexes, and hydrocarbyl metals, such as alkyl, cycloalkyl, aryl, alkyl aryl and aryl alkyl metals.

The intrcducticn of the metal M advantagecusly takes place with the aid of a solution in an organic solvent of the organanetallic canpound of said metal M. It is also possible to use organhalogen crpounds of the metals M. Carpounds of metals M are in particular a a tetrabutyl tin, tetramethyl tin, tetraprcopyl gennaniun, tetraethyl "JO lead, indin acetyl acetcnate and triphenyl indixn.

a.

The impregnatin solution is chosen fran within the graup ccstituted by paraffin, naphthene or aromatic hydrocarbcns containing 6 to 12 carbon atarns per molecule and halogen-containing organic :15 canpounds containing 1 to 12 carbcn atans per molecule. Reference is made to n-heptane, methyl cyclohexane, toluene ad chloroform.

It is also possible to use mixtures of the solvents defined hereina before.

This introduction method for the metal M has already been described in US patent 4548918. However, the canbination of the platinun fanily metal intrcductimn methcd and the metal M intrductici methcd produces a particular synergian.

The MFI zeolite of the catalyst used in the invention contains by -8- *9*e9.

I.

S

0 a. 4@ S

U

.0 4~ a weight approximately 0.01 to 2 and more particularly approximately 0.1 to 0.5% of at least one noble metal from the platinum family, approximately 0.005 to 0.60 and preferably 0.01 to 0.50% of tin and/or 0.005 to 0.70 and preferably approximately 0.01 to 0.60 and more particularly 0.02 to 0.50% of at least one metal chosen within the group constituted by germanium, lead and indium.

When there are at least two metals chosen from within the group constituted by tin, germanium, lead and indium, the total content of metals in said group is approximately 0.02 10 to 1.20, preferably 0.02 to 1.0 and more particularly 0.02 to 0.8%.

It is possible to use either a coarmon solution of the metals which it is wished to deposit n the zeolite, or separate solutions for the metal from the platinum family and for the additional metal or metals. When several solutions are used, it is possible to carry out intermediate calcinations and/or dryings. Normally the process is completed by a calcination at e.g. between approximately 500 and 1000°C, preferably in the presence of free oxygen, e.g. by carrying ut air scavenging.

Following the preparation of the catalyst, the latter is generally calcined at between 450 and 1000 but after calcination the catalyst can advantageously undergo an activation treatment under hydrogen and at high teperature, e.g. 300 to 500C, in order to a a 9 obtain a more active metallic phase. The procedure of this treatment under hydrogen e.g. consists of a slow temperature rise under a hydrogen stream until the ma> Ium reduction temperature is e.g.

between 300 and 500*C and preferably between 350 and 450*C and this is maintained for 1 to 6 hours.

see*, 00 00 6 000.

0 s 0** 0 i0 10 0* S 0 This preparation procedure for the catalyst leads to a solid in which the metals are homogeneously distributed throughout the volume of the catalyst grain and are in a metallic state following the reduction treatment under hydrogen scavenging between 300 and 500"C and maintaining for 1 to 6 hours under hydrogen at the final temperature chosen.

S

000000 4 0000 0e 0 60 0S 0 0 00 An advantageous method for the preparation of catalysts can involve 15 the following stages: The MFI zeolite is lpregnated with an aqueous solution of a copound of a metal chosen from within the group constituted by tin, gemanium, indium and lead.

The product obtained in stage is dried.

The product obtained in stage is calcined.

The product obtained in stage is impregnated with a platinum acetyl acetonate solution n toluene.

The product obtained in stage is dried.

The product obtained in stage is calcined.

The product obtained in stage is reduced under a hydrogen stream.

**g St S5I

S

iS 5 55 @5 a

SOS.

05 Another advantageous method for the preparation of catalysts can involve the following stages: The MFI zeolite is inpregnated with an aqueous solution of a canpound of a metal chosen franom within the group constituted by tin, indium, germaniumrn and lead.

The product obtained in stage is dried.

The product obtained in stage is calcined.

The product obtained in stage is inpregnated with an =moniacal tetraanmine platinum chloride solution.

10 The product obtained in stage is dried.

The product obtained in stage is calcined.

The product obtained in stage is reduced under a hydrogen stream.

15 Another advantageous method for the preparation of catalysts rcan be carried out with the following stages: The MFI zeolite is inpregnated with an amoniacal tetraannine platinum chloride solution.

The product obtained in stage is dried.

The product obtained in stage is calcined.

The product obtained in stage is reduced under a hydrogen stream.

The product obtained in stage is contacted with a hydrocarbon solvent and with said organic compound of metal M, e.g. by immersing the mass in a hydrocarbon solvent already containing the 11 organic carpound or by innmersing the mass in a hydrocarbon solvent and than injecting into the mixture obtained a solution of the organic coarpound of said metal M in a hydrocarbon solvent and e.g.

that in which said mass has been inmersed.

The product obtained in stage is reduced under a hydrogen streanm sees The catalyst can also contain a support or an anorphous matrix, e.g.

chosen fran anong magnesiun, aluminixum, titanium, zirconiun, 10 thorium, silicon and boron oxcides, considered singly or in mixtures.

It is also possible to use carbon. The preferred support is alumina. The specific surface of the alumina is aivantageously between 50 and 600 m2/g and preferably between 150 and 400 m 2 /g.

15 The ,olite containing the various metals described hereinbefore can be shaped with the support using any known procedure, e.g.

pelletiz:ng, extrusion, drageification, droplet coagulation, drying by atanizaticon, The catalyst then contains 1 to 99% by weight zeolite containing the different mtetals, the residue being constituted by the support or anorphous ma-trix.

The catalyst is used in a process for the aranatizati of hydrocarbons containing 5 to 9 carbon atans per molecule, under the 12 converntional cperating conditions for such a process. The follaowing examples illustrate the invention without limiting its scope.

ExqT e 1~ The aim is to transform a charge constituted by a mixture of hydrocarbons containing 5 or 6 carbon atoms in the presence of a FI zeolite-based catalyst with a Si/Al atonic ratio of 45 containing 0*0*0 platinum and a metal chosen from within the group constituted by tin, 6 germanium, indiumn and lead.

*0

S

0 Preparatian of the MFI zeolite:

SS

The MFI zeolite is synthesized in the presence of an organic structuring agent using knevn fonrmulations (US-A-3,702,886). This *ses: zeolite is transformed into the H form by calcining in an air- 0 135 nitrogen mixture (10% axygen in the mixture) at 550*C and for 4 hours, three exchanges in SN NI 4

N

3 at 100*C and calcinlng in air at 530*C for 5 hours with a flow rate of 5 l/h/g.

The Si/Al atonic ratio of the HMFI zeolite is 45 and its porous volume measured by nitrogen adsorption at 77 K exceeds 0.160 cm 3g.

The metals are deposited on the MFI zeolite according t tthe following procedures: Catalyst

A

The MI zeolite is impregnated by an aqueous tin chloride 13 solution, so that the final tin concentration of the catalyst is 0.25% by weight.

The product obtained in stage is dried for 1 hour at 100 to 120*Co The product obtained in stage is calcined for 2 hours at 530 *C.

The product obtained in stage is irpregnated by an aquea hexachlorcplatinic acid solution so as to obtain 0.3% platinum on the final catalyst.

10 The product obtained is dried for 1 hour at 100 to 120°C.

Calcining takes place for 2 hours at 530°C.

*O00

S

egO.

C

0S OS S C

C

5 S

*J

US

Catalyst A: 0.3% Pt and 0.25% Sn/MFI.

90.0,.

0 15 00 0* *0 Catalyst B The MFI zeolite is impregnated according to the sane procedure as for catalyst except that the tin chloride is replaced by tin acetate, the remainder of the procedure being unchanged.

Catalyst B: 0.3% Pt and 0.25% Sn/MFI.

Catalyst C The MFI zeolite is inpregnated according to the sane procedure as for catalyst B, except that the platinum is impregnated by means of an amnoniacal tetcaannine platinum chloride solution, the rest 14 of the proceczre being unchanged.

Catalyst C: Pt 0.3% ad Sn to*e *see 9 0 909, 0#600: a 0 @06 6g o of Sr S. S Catalyst D (carparative catalyst) The MFI zeolite is Thpregnated by an amoniacal tetraarmine platinun chloride solution, so as to obtain a platinuTi ooncentration of 0.3% by weight on the final catalyst.

10 Ctalyst D: Pt 0.3%/MFI.

Exaggle 2 The above-prepared catalysts were subject to an arniatization test of a C 5

-C

6 fraction with the following xneposition by weight): Paraffins 90.0% 5.4% Nphthenes 3.7% 0.9% The operating Teqerature Pressure conditions are as folloks: 4800C 0.25 mnegapascal 3h 15 The results of the comparative tests for catalysts A to D and the MFI zeolite only are given in table 1.

TABLE 1 Catalyst Conversion by weight .556 500e 0e0

S

S.

S

0 6 or e MFI zeolite Catalyst A Catalyst B Catalyst C Catalyst D Selectivity

CH

4 C 2 6

C

2

H

4 35 25 5 12 5 13 4 10 25 20 by

C

3

H

8 CH C3 6 15 15 14 12 10 weight) C4H10

CH

4 8 20 7 5 8 15.

Aramatics 61 63 66 staff: Sao* *969 05 40 Exaple 3 In order to prepare catalysts E, F and G respectively, an ipregnation procedure strictly identical to that used for the preparation of catalyst C is used, except that the tin, acetate is replaced by germaniaun axalate (catalyst lead nitrate (catalyst F) and indium nitrate (catalyst the remainder of the procedure remaining unchanged.

Catalyst E: Catalyst F: Catalyst G: Pt 0.3% and Ge 0.20%/MFI Pt 0.3% and Pb 0.35%/MFI Pt 0.3% and In 0.25%/MFI.

16 Table 2 gives the results of the aranatization tests for the C5 6 fractionc performed with these catalysts under the sane conditions as defined in example 2.

TABLE 2 88.0 0 *eeg t1 0* ee 0 15

S.

os S.

10 O 0

S'S.

Catalyst Conversion by weight Selectivity CH4 C 2

H

6

C

3

H

C+

C

2

H

4

C

3

H

6 by weight) C4H10 Armatics 4

C

4

H

8 Catalyst Catalyst Catalyst Catalyst Catalyst

S.

Example 4 The above-prepared ca';alyst D is reduced under a hydrogen strean for 2 hours at 450*C. 100 g of this catalyst are inrersed in 300 an3 of n-heptane. Into the catalyst-containing n-heptane are then injected 2 g of a tetra n-butyl tin solution in n-heptane (10% tin). The contact between the platinum catalyst and the tetra n-butyl tin solution is maintained for 6 hours at the reflux termperature of the heptane. The irmpregnation solution is then discharged and three washing operations are carried out with pure n-heptane at the reflux 17 teiperature of the n-heptane. The catalyst is then dried. It can then undergo either a calcination in air for 2 hours at 500*C and followed by a reduction under a hydrogen strean at 450"C and for 2 hours before being introduced into the reactor, or undergo a direct reduction under a hydrogen stream at 450°C for 2 hours before being fed into the reactor.

a This gives catalyst H: Pt: 0.3% and Sn: 0.2%/MFI.

eeerft A 10 The aranatization results with respect to the C5-C 6 fraction under a o* conditions identical to those of example 2 are given in table 3.

TABLE 3 °•Selectivity by weight) s 15 Catalyst Conversion by weight CH4 CH 6

C

3

H

8

C

4

H

10 Armnatics C h' C 3

H

6

C

4

H

8 atalyst D 95 25 20 10 15 Catalyst C 94 4 10 12 8 66 Catalyst H 95 4 8 10 8 Thus, a good aromatic product selectivity is obtained with the catalysts-in accordance with those used in the present invention B, C, E, F, G and H).

Claims (7)

1. Process for the aromatization of hydrocarbons containing 5 to 9 carbon atoms per molecule, characterized in that it is carried out in the presence of at least one catalyst containing a MFI structure zeolite containing at least one noble metal from the platinum family Q* *i and at least one additional metal chosen fran the group constituted by tin, germanium, lead and indium. C 10

2. Process according to claim 1, wherein said zeolite contains at o least one noble metal from the platinum family in a quantity of approximately 0.01 to 2% by weight and at least one additional metal chosen fromn within the group constituted by tin, qgennaniun, lead and indium in a quantity of approximately 0.005 to 0.60% by 6# g weight for the tin and a quantity of approximately 0.005 to 0.70% by weight for the germaniumn, lead or indium.

3. Process according to claim* 1 wherein said zeolite contains at least one noble metal from the platinum family in a quantity of approximately 0.1 to 0.5% by weight and at least one additional metal chosen fromn within the group constituted by tin, germanium, lead and indium in a quantity of appr dmately 0.01 to 0.50% by weight for the tin and in a quantity of approxmately 0.01 to 0.60% by weight for the germanium, lead or indium.

4. Process according to claim 1, wherein said zeolite contains as additional metals tin and at least one metal chosen from within the group constituted by germanium, lead and indium, the total additional metal content of said zeolite being approximately 0.02 to 1.20% by weight.

Process according to claim 1, wherein the catalyst also contains an amorphous matrix.

6. Process according to claim 5 wherein the catalyst contains by weight 1 to 99% of said zeolite and 99 to 1% of said matrix.

7. Process according to claim 5 or claim 6, wherein said matrix is alumina. DATED THIS 25TH DAY OF JUNE 1993 20 INSTITUT FRANCAIS DU PETROLE By its patent attorneys: GRIFFITH HACK CO Fellows Institute of Patent Attorneys of Australia. *a a a *e *oo aeQ A iI A &*of 0 DESCRIPTIVE ABSRACT 6 The inventicn relates to a process for the catalytic aromatizaticn 01 00 of hydrocazbcww containing 5 to 9 carbons atoms per molecule. 0 SO It is diaracterized by the use of a catalyst containing a MFI meolite containing at least cne noble metal fran the platinum farnly S a- at least one alditicnal metal chosen fran the group constituted by tin, gemnanimn, lead and ind n, ad cptionally an anorphous o pmatrix. '*r a o