GB2245001A

GB2245001A - Catalyst compositions containing metal ion-exchanged zeolites

Info

Publication number: GB2245001A
Application number: GB9012991A
Authority: GB
Inventors: Abraham Araya
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1990-06-11
Filing date: 1990-06-11
Publication date: 1991-12-18
Also published as: GB9012991D0; EP0461851A3; EP0461851A2; IN172882B

Description

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FCC PROCESSING USING CATALYST COMPOSITIONS CONTAINING METAL ION-EXCHANGED ZEOLITES This invention relates to FCC processing using catalyst compositions containing metal ion-exchanged zeol-4tes. In particular, the invention relates to FCC processes using a catalyst composition containing a zeolite into which a metal, especially zinc, ion has been incorporated by ion-exchange, which composition has improved catalytic properties.

Catalysts containing crystalline zeolites dispersed in an inorganic oxide matrix have been widely utilized in the Droduction of gasoline by cracking of netroleum-derived feedstocks, particularly gas oil, using FCC technology.

Typically, in FCC, wide-pore zeolites having a faujasitic structure (X or Y zeolites) have been emploved but improvements have been achieved by including in the catalyst composition other additional zeolites, including medium-pore zeolites of the ZSM-5 family or by modification of the zeolite, including ion- exchange treatment.

Such improvements include increased conversion, increased aromaticity of the gasoline, increased branching of the paraffins in the gasoline and improved 2 passivation of certain metal contaminants present in the petroleum feedstock, especially vanadium and nickel which produce undesirable changes in the activity and selectivity of the contaminated catalyst. However, to date there has been no disclosure of the use of a catalyst composition so as to achieve all of these advantages at one and the same time.

Thus, US-A-4363720 and US-A-4500645 disclose the incorporation, separately into a zeolite catalyst composition, of a zinc treatment agent, especially zinc oxide. The zinc oxide is introduced into the composition by treating the zeolite with a zinc nitrate solution, subsequent processing of the catalyst compositJon resulting in precipitation of zinc oxide. According to US-A-4363720, this results in passivation of contaminant metals, especially nickel, while according to US-A-4500645, a reduction in the amount of gaseous component is achieved even when maintaining a high conversion so as to produce selectively a middle fraction.

US-A-3835030 is directed mainly to achieving improved activity of a zeolite by increasing its silica/alumina ratio. However, an additional improvement in activity is achieved by ion-exchanging the zeolite with a metal, such as a zinc, cation.

1 3 EP-A-0258726 describes FCC catalyst compositions containing zeolite 3 on a silica sol matrix. The zeolite 3 has, ion-exchanged onto it, Ga and/or Zn so as to increase the aromatic content of gasoline subjected to FCC using the catalyst. The catalyst is prepared by heating the zeolite B in a solution of a salt of the metal, mixing the ion-exchanged zeolite 3 with the silica sol, oven drying, screening and then calcining.

GB-A-1393501 describes zeolite (especially zeolite Y) catalysts ion exchanged with rare earth metal and zinc ions in controlled relative proportions so as to achieve improved thermal and steam stability properties. The ion exchange of the rare earth metal and/or zinc can be carried out prior or subsequently to incorporation of the zeolite in a matrix, especially kaolin.

Surprisingly, we have found that a zeolite catalyst composition comprising a zeolite incorporated within a matrix, which zeolite contains certain metal, especially zinc, ions, as later described, when used as a catalyst in hydrocarbon cracking, especially FCC, exhibits simultaneously each of the following phenomena, i) activity enhancement, as compared with a composition in which the zeolite has not been metal ion exchanged, ii) enhanced aromatization of the gasoline 1 4 fraction (iii) enhanced branching of paraffins of the gasoline fraction, (iv) vanadium passivation of the catalyst and (v) nickel passivation of the catalyst.

Hereinafter, such a zeolite composition is referred to as "a metal ion exchanged zeolite catalyst composition".

Aspects of the present invention include 1) a method of cracking a vanadium and/or nickel containing hydrocarbon feedstock, which method comprises contacting the feedstock with the metal ion exchanged zeolite catalyst composition, 2) use of the metal ion exchanged zeolite catalyst composition in the passivation of vanadium and/or nickel during the cracking of a hydrocarbon feedstock, 3) a method of cracking a hydrocarbon feedstock containing nickel and vanadium with a zeolite catalyst composition and, during the said cracking, simultaneously achieving enhanced activity of the zeolite composition, enhanced branching of paraffins and aromatization of the gasoline fraction and passivation of both the nickel and vanadium, which method comprises a step, prior to cracking the hydrocarbon feedstock, of subjecting the zeolite of the zeolite catalyst composition to ion exchange with a metal, and 4) a method of simultaneously (a) cracking, with a zeolitic composition, a hydrocarbon feedstock, containing nickel and vanadium to obtain a conversion, especially in FCC, of at least 50% and a gasoline fraction containing aromatic and branched paraffin compounds and (b) passivating the nickel and the vanadium, wherein the zeolite of the zeolite catalyst composition is ion-exchanged with a metal.

The metal ion exchanged zeolite catalyst composition is especially effective in simultaneously achieving the above phenomena (i)-(iv) if it is obtained by preparing a composition comprising a protonated, for example an ammonium ion exchanged, crystalline zeolite and a matrix material and thereafter subjecting the resultant composition to ion-exchange to provide, on the composition, ions of the metal.

The metal may be any of zinc, titanium, copper, chromium, manganese, cobalt, gallium, germanium, indium, tin, antimony and iron. Zinc is especially preferred.

The amount of the metal, especially zinc, by weight of the total catalyst composition is preferably 0.1-3, especially 0.5-2, more especially 0.012 moles of the metal per 100g total catalyst composition.

6 For zinc, expressed as metallic zinc, the amount, by weight of the total composition, is preferably 0.052%, especially 0.1-1%, more especially 0. 8%. When expressed as ZnO, a typical range of amounts is 0.02-2%.

The crystalline zeolite component of a composition used in the method of the present invention, which is usually present in the range from about 5% to about 50%, especially about 20 to about 40%, by weight of the total composition, may generally be described as a crystalline, three dimensional, stable structure enclosing cavities of molecular dimensions. Most zeolites are based on aluminosilicate frameworks, the aluminium and silicon atoms being tetrahedrally coordinated by oxygen atoms. However, for the purposes of our invention we include, as the "zeolites" which are to be subjected to metal ion exchange, similar materials in which atoms of other elements are present in the framework, such as boron, gallium, germanium, chromium, iron, and phosphorus. Further we include materials such as pillared interlayered clays ("PILCS"), which have many of the catalytically valuable characteristics of the aluminosilicate zeolites. We also include all modifications to the above materials, whether obtained by ion-exchange, impregnation, hydrothermal or chemical treatments.

7 Zeolites which can be incorporated in the matrix prior to metal ion exchange in preparing zeolite compositions used in the methods of this invention can be natural or synthetic in origin. These naturally 5 occurring zeolites include faujasite, erionite, offretite, mordenite. Suitable synthetic zeolites are zeolites L,X,Y, beta, omega, the EU types, the Fu types, the Nu types, the ZSM types, the ALP04 types, the SAPO types, and other similar materials. The effective pore size of the synthetic materials is preferably between 0.5 and 1.5 nanometers, and the preferred zeolites are those with the faujasite framework and silica/alumina ratios >3, thus including synthetic zeolite Y and the various form of Y which have been made more siliceous by chemical, hydrothermal or thermal treatments.

In a preferred embodiment of the invention, the preparation of the zeolitic composition includes the step of converting the zeolite to a form which is most applicable for the catalytic cracking method prior to the metal ion exchange. In general this involves a sequence of preliminary ion-exchange and calcination treatments to introduce acid groups into the zeolite, stabilise the structure, and remove alkali metal cations. The preferred method of achieving this end, well known in the art, is to exchange the zeolite with solutions containing ammonium ions and/or rare earth 8 ions (either a pure rare earth compound or a mixture).

Such treatment can be carried out either on the zeolite before or after its incorporation into the matrix, and can be carried out on a filter press, filter 5. table, or filter belt, or by slurrying the zeolite/catalyst in a tank.

An especially preferred zeolite is a zeolite Y, which before the metal ion-exchange is in the NH 4-Y or H-Y form.

The matrix into which the zeolite is incorporated can be selected from a wide range of components. Suitable components include: naturally occurring or synthetic clays, including kaolin, halloycite and montmorillonite; inorganic oxide gels such as silica gel, and including binary gels such as silica-alumina, silica-zirconia and silica-magnesia, aluminium phosphates, ternary combinations such as silicamagnesia-alumina; and crystalline inorganic oxides such as silica, alumina, titania and zirconia.

An especially preferred matrix comprises an inorganic oxide gel, such as a silica sol and alumina, for example, a crystalline alumina.

A typical catalyst composition prior to the 9 metal ion exchange step comprises, by weight of the total weight of the composition, zeolite - HY - 20-40, especially 25-35, especially 30% inorganic - 10-30, 20-30, 25% oxide gel alumina - clay l 3-15, 11 5-15, 91 10% 11 35% The metal ion exchange step may be carried out by treating the composition with an aqueous solution of the metal salt at a temperature of from ambient, for example 250C, up to about 1000C, preferably (at least for zinc) at least 600C, more preferably at least 700C, especially 80'C. The resultant product may be filtered, washed and dried, preferably at a temperature just above boiling, for example, at 1050C.

We find, surprisingly, that a metal ion exchanged zeolite catalyst composition, especially when the ion exchanged zeolite is prepared by the method, described above, and more especially such a catalyst composition ion-exchanged with zinc, may be used to provide, at one at the same time, (i) activity enhancement, (ii) increased aromaticity and branched chain paraffin content of the gasoline and (iii) improved passivation of both vanadium and nickel.

The invention will now be described in more detail with reference to the following Examples.

In the Examples, the following definitions apply.

Definitions Kinetic Conversion Kinetic H 2 Specific Coke Wt. % Conversion 100 - wt. Conversion Wt. % H 2 Kinetic Conversion Wt. Coke - 0.3 Kinetic Conversion 1 11 Example 1 - Preparation of Zinc Containing Cataivst The following composition was slurried into 3000 mls of deionized water, namely 300g zeolite HY, 250g silica sol binder, 100g pseudo-boehmite alumina and 35t.g clay. The slurry was spray-dried, washed and subjected to ammonium ion-exchange in the usual manner. The ammonium exchanged composition was filtered, washed and oven-dried. The resultant composition (100 gms) was slurried in 300 ml deionized water at 800C. To the slurry catalyst was addded 4.9g of Zn(NO 3)2.6H 20 dissolved in 20 ml deionized water. The mixture was stirred at 800C for a further ten minutes, then filtered, washed and dried at 1050C for sixteen hours.

The parent catalyst was labelled as Catalyst A and the zinc exchanged catalyst as Catalyst B. Catalyst B was analysed for zinc and contained 1% ZnO.

ExamDle 2 - Microactivity Test (MAT) of Catalysts A and B Prior to MAT evaluation, both catalysts A and B were hydrothermally deactivated in 100% steam at 8160C for 5 hours. MAT test conditions employed were as follows:

Feed type Kuwait waxy distillate Temperature - 9601'F Weight Hourly Space - 13.5 12 Velocity (WHSV) The MAT data of major fields for catalysts A and B is given in Table 1 below. Table 1 MAT Data

Catalyst A Catalyst B Conversion (wt.%) 67 76 Gasoline (wt.%) 46.3 51.7 LCO (wt.%) 22.8 18.8 HCO (wt.%) 10.4 5.6 LPG (wt.%) 16.1 17.2 Dry Gas (wt.%) 1.9 2.4 Specific Coke 1.13 1.28 Kinetic H2 0.048 0.075 The fact that wtA conversion by Catalyst B after severe steam deactivation is 9 units higher than that of Catalyst A (Table 1) is a clear indication that zinc has enhanced the activity of the catalyst significantly (though this enhanced activity is accompanied by a high level of H 2) It might have been considered that such enhanced activity was associated (as in rare earth containing catalysts) merely with stability enhancement by the zinc of the zeolite structure. In order to determine whether or not this was the case both the fresh and steam 13 deactivated catalyst samples for both catalysts A and B were subjected to surface area and crystallinity measurements. It was found that surface area retention and crystallinity for both catalysts A and B were similar (both about 67% for catalyst A and both about 68% for catalyst B). This shows clearly that zinc does not stabilize the zeolite structure and indicates that enhancement of activity is by a different mechanism.

From a partial analysis of the gasoline produced by catalysts A and B in the MAT unit it appeared the gasoline composition contained significantly increased amounts of both aromatic and branched chain paraffin compounds.

ExamDle 3 - Nickel Passivation Catalysts A and B were impregnated with 1000 ppm of Ni. The Ni impregnated catalysts were steam deactivated at 8160C for 5 hours and their catalytic performance was evaluated by MAT.

The MAT data of major yields for the Ni impregnated catalysts is given in Table 3 below.

1 14 Table 3 MAT Data for Ni Impregnated Catalysts Catalyst A Catalyst B Conversion (wt.%) 67 75 Gasoline (wt.%) 45.6 49.0 LCO (wt.-%) 21.1 18.2 HCO (wt.%) 10.7 6.3 LPG (wt.%) 16.7 18.9 Dry Gas (wt.%) 2.1 2.8 Specific Coke 1.20 1.41 Kinetic H. 0.095 0.11 Nickel is a well known dehydrogenating catalyst. Thus, the degree of the increase of H. yield in the presence of nickel can be used to assess the nickel tolerance of FCC catalysts. To this end, the kinetic H2 of catalysts A and B in the presence and absence of nickel is compared in Table 4 below.

Table 4

ComDarison of Ni Tolerance for Catalysts A and B Kinetic Hydrogen 0 ppm Ni 1000 ppm Ni % Increase Catalyst A 0.048 0.095 98 Catalyst B 0.075 0.11 46 Example 4 - Vanadium Passivation Catalysts A and B were impregnated with 3000 ppm of V. The V impregnated catalysts were steam deactivated at 788C for 5 hours and their vanadium tolerance assessed by MAT, and the data of major yields for the V impregnated catalysts is given in Table 5 below. Table 5 MAT Data for V Impregnated Catalysts Catalyst A Catalyst B -------------------------------------------------------- Conversion (wt.-W) 66 77 Gasoline (wtA) 44.0 49.5 LCO (wtA) 22.2 17.6 HCO (wtA) 11.5 5.9 LPG (wt.U 15.8 18.5 Dry Gas (wt.%) 2.5 3.2 Specific Coke 1.83 1.66 Kinetic H 2 0.19 0.12 Vanadium selectively attacks the zeolite structure and this leads to loss in catalytic activity and an increase in H 2 and coke yields.

The activity of catalyst B in the presence of V is 11 units higher than that of catalyst A. Moreover, the specific coke and kinetic H2 for catalyst B is lower 16 than that of catalyst A. This clearly demonstrates the vanadium passivating property of zinc.

From the above Examples, it can be seen that a method embodying the invention for cracking a hydrocarbon feedstock using a metal ion exchanged zeolite catalyst composition provides, at one and the same time, increased conversion, and increased aromatic and branched chain paraffin content of the gasoline so that enhanced motor octane is to be expected.

Furthermore, the composition is also, at the same time, highly effective in passivating both nickel and vanadium.

17

Claims

1. A method of cracking a vanadium and/or nickel containing hydrocarbon feedstock, which method comprises contacting the feedstock with a zeolite catalyst composition comprising a zeolite incorporated within a matrix, the zeolite containing metal ions selected from zinc, titanium, copper, chromium, manganese, cobalt, gallium, germanium, indium, tin, antimony and iron.

2. A method of cracking a hydrocarbon feedstock containing nickel and vanadium containing nickel and vanadium with a zeolite catalyst composition and, during the said cracking, simultaneously achieving enhanced activity of the zeolite composition, enhanced brancing of paraffins and aromatization of the gasoline fraction and passivation of both the nickel and vandium, which method comprises a step, prior to cracking the hydrocarbon feedstock, of subjecting the zeclite of the zeolite catalyst composition to ion exchange with a metal selected from zinc, titanium, copper, chromium, manganese, cobalt, gallium, germanium, indium, tin, antimony and iron.

3. A method of simultaneously (a) cracking, with a zeolite catalyst composition, a hydrocarbon feedstock containing nickel and vanadium to obtain a conversion of at least 50% and a gasoline fraction containing 1 1 18 aromatic and branched paraffin compounds and (b) passivating the nickel and the vandium, wherein the zeolite of the zeolite catalyst composition is ionexchanged with a metal selected from zinc, titanium, copper, chromium, manganese, cobalt, gallium, germanium, Indium, tin, antimony and iron.

4. A method according to any preceding claim in which the zeolite catalyst composition has been prepared by incorporating a zeolite in a matrix and thereafter subjecting the zeolite containing matrix to ion exchange with the metal ion.

5. A method according to claim 4, wherein the zeolite catalyst composition has been prepared by a method comprising the steps of (a) incorporating a zeolite in a matrix material to provide a zeolite composition, (b) prior to, simultaneously with or subsequently to step (a), subjecting a zeolite to ammonium ion exchange, and (c) after steps (a) and (b) subjecting the zeolite composition to metal ion-exchange to provide the metal ions on the zeolite selected from zinc, titanium, copper, chromium, manganese, cobalt, gallium, germanium, indium, tin, antimony and iron.

6. A method according to any preceding claim, w Q 19 wherein the metal ions are present in an amount, expressed as the lowest metal oxide, of from 0.1 to 3% by weight of the total weight of the catalyst.

7. A method according to any preceding claim, wherein the metal ion is selected from zinc, titanium and copper.

8. A method according to claim 7, wherein the metal ion is zinc.

9. A method according to any preceding claim, wherein the zeolite is zeolite Y.

10. A method according to any preceding claim, wherein the matrix comprises at least one of a silica sol and alumina.

11. A method according to claim 10, wherein the 15 matrix comprises a silica sol and alumina.

12. A method according to claim 5, wherein subsequent to the said incorporation step (a) but prior to the said metal ion-exchange step (c), the zeolite is subjected to the ammonium ion exchange step (b).

13. A method according to any one of the preceding 1 claims, wherein the metal ions have been introduced into the zeolite catalyst composition by heating a slurry of the composition in a solution of a salt of the metal at a temperature of from ambient temperature to 1000C inclusive.

14. A method according to claim 13, wherein the metal salt is zinc nitrate.

15. A method according to any preceding claim, which includes the preliminary step of subjecting the zeolite catalyst composition to hydrothermal deactivation.

16. A method according to any preceding claim substantially as herein described and exemplified.

17. Use of a zeolite catalyst composition in the passivation of vanadium and/or nickel during the crakcing of a hydrocarbon feedstock, whcih zeolite catalyst composition comprises a zeolite incorporated within a matrix, the zeolite containing metal ions selected from zinc, titanium, copper, chromium, manganese, cobalt, gallium, germanium, indium, tin, antimony and iron.

18. Use according to claim 17 for the simultaneous passivation of vanadium and nickel.

i 1 21

19. Use according to claim 17 or 18, in which the zeolite catalyst composition has been prepared by incorporating a zeolite in a matrix and thereafter subjecting the zeolite containing matrix to ion exchange with the metal ions.

20. Use according to claim 19, wherein the zeolite catalyst composition has been prepared by a method comprising the steps of (a) incorporating a zeolite in a matrix material to provide a zeolite composition, (b) prior to, simultaneously with or subsequently to step (a), subjecting a zeolite to ammonium ion exchange, and (c) after steps (a) and (b) subjecting the zeolite composition to metal ion-exchange to provide the metal ions on the zeolite.

21. Use according to any one of claims 17 to 20, wherein the metal ions are present in an amount expressed as the lowest metal oxide, of from 0.1 to 3 by weight of the total weight of the zeolite catalyst composition.

22. Use according to any one of claims 17 to 21, wherein the metal ion is selected from zinc, titanium and copper.

41, - 22

23. Use according to claim 22, wherein the metal ion is zinc.

24. Use according to any one of claims 17 to 22, wherein the zeolite is zeolite Y.

25. Use according to any one of claims 17 to 23, wherein the matrix comprises at least one of a silica sol and alumina.

26. Use according to claim 25, wherein the matrix comprises a silica sol and alumina.

27. Use according to claim 20, wherein subsequent to the said incorporation step (a) but prior to the said metal ion-exchange step (c), the zeolite is subjected to the ammonium ion exchange step (b).

28. Use according to any one of claims 17 to 26, wherein the metal ions have been introduced into the zeolite catalyst composition by heating a slurry of the composition in a solution of a salt of the metal at a temperature of from ambient temperature to 1000C inclusive.

29. Use according to claim 28, wherein the metal salt is zinc nitrate.

1:

1 I- 23

30. Use according to any one of claims 17 to 29, which includes the preliminary step of subjecting the zeolite catalyst composition to hydrothermal deactivation.

31. Use according to any one of claims 17 to 30 substantially as herein described and exemplified.

Published 1991 at The Patent Office, Concept House. Cardiff Road, Newport. Gwent NP9 I RH. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point, Cwrnfelirifach. Cross Keys, Newport, NP I 7HZ. Printed by Multiplex techniques ltd, St Mary Cray. Kent.