CATALYST SYSTEM FOR DEWAXING

Abstract

A catalyst system for dewaxing of a hydrocarbon feedstock comprising at least two catalytic sections, the first section comprising a first dewaxing catalyst and a subsequent section comprising a second dewaxing catalyst, wherein the first dewaxing catalyst is a ZSM-12 zeolite based catalyst and the second dewaxing catalyst is a EU-2 and/or ZSM-48 zeolite based catalyst. The catalyst system displays enhanced performance when compared to systems containing either ony ZSM-12 based catalyst or EU-2/ZSM-48 based catalyst only.

Claims

1. A catalyst system for dewaxing of a hydrocarbon feedstock comprising at least two catalytic sections, the first section comprising a first dewaxing catalyst and a subsequent section comprising a second dewaxing catalyst, wherein the first dewaxing catalyst is a ZSM-12 zeolite based catalyst and the second dewaxing catalyst is a EU-2 and/or ZSM-48 zeolite based catalyst.

2. The catalyst composition of claim 1, wherein said ZSM-12 zeolite is present in said first dewaxing catalyst composition in an amount of at least 10 wt. % and at most 70 wt. % and said first dewaxing catalyst composition further comprises a binder in an amount of at least 30 wt. % and no more than 90 wt. %, with such % wt being based on the dry weight of said composition.

3. The catalyst system of claim 1, wherein said EU-2 and/or ZSM-48 zeolite is present in said second dewaxing catalyst composition in an amount of at least 15 wt. % and at most 70 wt. % and said second dewaxing catalyst composition further comprises a binder in an amount of at least 30 wt. % and no more than 85 wt. %, with such wt. % being based on the dry weight of said composition.

4. The catalyst system of claim 1, wherein the first dewaxing catalyst and the second dewaxing catalyst each comprise a noble metal component.

5. The catalyst system of claim 1, wherein the ZSM-12 zeolite has a silica to alumina molar ratio of at least 50:1 and at most 250:1.

6. The catalyst system of claim 1, wherein the EU-2 and/or ZSM-48 zeolite has a silica to alumina molar ratio of at least 60:1 and at most 300:1.

7. The catalyst system of claim 1, wherein the catalyst volume ratio of the first dewaxing catalyst to the second dewaxing catalyst is in the range of 10:90 to 90:10.

8. The process for dewaxing of a hydrocarbon feedstock comprising contacting a hydrocarbon feedstock with a catalyst system according to claim 1 at a temperature from 200 C. up to 450 C. and a pressure of from 5 to 20010.sup.5 Pa.

9. The process according to claim 8, in which process the feedstock is a wax-containing feed that boils in the lubricating oil range having a 10% distillation point at 200 C. or higher, as measured by ASTM D-2887-93.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0037] FIG. 1 shows performance data of catalyst stacks with ZSM-12 and EU-2 based catalysts when compared to ZSM-12 only and EU-2 only catalysts, respectively. Also the performance data of a ZSM-12/EU-2 catalyst mixture is shown.

[0038] Legends: wof % is the wt. % on feed. C1-C4 indicates the amount of product containing 1, 2, 3, or 4 carbon atoms. C5-150 C. indicates the amount of product with carbon number 5 up to products that have a boiling point of 150 C. 150-370 C. indicates the amount of product with a boiling point in the range between 150 and 370 C. >370 C. indicates the amount of product with a boiling point of 370 C. or higher as measured with ASTM D2887-93. Treq.dPP 75 C. stands for the required reactor temperature to obtain a pour point (PP) improvement of 75 C.

[0039] The method of the invention will now be illustrated by the following non-limiting examples.

EXAMPLES

Example 1

ZSM-12 Composition

[0040] An extrudable mass was prepared by combining ZSM-12 zeolite having a SAR of 90 from Zeolyst International with amorphous silica, ammonia and water. The mass was extruded to give extrudates having a cylinder shape and an average diameter of 1.6 mm. These extrudates were dried and calcined resulting in white extrudates.

[0041] The extrudates were treated unstirred at a temperature of 90 C. for 5 hours with aqueous ammonium hexafluorosilicate (AHS) solution. The weight ratio of solution to extrudates was 5:1. Subsequently, the extrudates were separated from the solution, washed with deionized water, and dried and calcined.

[0042] Thereafter, 0.7% wt./wt. platinum was incorporated into the composition by pore volume impregnation during about 10 minutes with an aqueous solution containing tetramine platinum nitrate (Pt(NH3)4(NO3)2) (3.37% wt./wt. Pt).

[0043] The impregnated composition was not washed, but equilibrated during 1.5 hours on a rolling bed, dried and calcined. Then, the catalyst was cooled down to room temperature.

Example 2

EU-2 (ZSM-48) Composition

[0044] Zeolite EU-2 (ZSM-48) having a SAR of 110 was prepared as described in US 4741891 A. An extrudable mass was prepared by combining EU-2 with amorphous silica, ammonia and water. The mass was extruded to give extrudates having a cylinder shape and an average diameter of 1.6 mm. These extrudates were dried and calcined resulting in white extrudates.

[0045] The extrudates were treated unstirred at a temperature of 90 C. for 5 hours with aqueous ammonium hexafluorosilicate (AHS) solution. The weight ratio of solution to extrudates was 5:1. Subsequently, the extrudates were separated from the solution, washed with deionized water, and dried and calcined.

[0046] Thereafter, 0.7% wt./wt. platinum was incorporated into the composition by pore volume impregnation during about 10 minutes with an aqueous solution containing tetramine platinum nitrate (Pt(NH3)4(NO3)2) (3.3% wt./wt. Pt).

[0047] The impregnated composition was not washed, but equilibrated during 1.5 hours on a rolling bed, dried and calcined. Then, the catalyst was cooled down to room temperature.

Example 3

Performance Testing of Stacked Catalysts

[0048] The catalysts of Examples 1 and 2 were dried at 250 C. for 3 hours. Subsequently, each of the catalysts was mixed with sufficient inert material (e.g. SiC) to assure proper plug flow conditions and loaded into a single tube test reactor of down flow mode (comparative examples). For preparing the stacked examples, the catalysts mixed with sufficient inert materialwere loaded on top of each other into a single tube test reactor of down flow mode.

[0049] In total, 4 stacked examples were prepared: [0050] (a) 50% EU-2/50% ZSM-12; [0051] (b) 25% ZSM-12/75% EU-2; [0052] (c) 50% ZSM-12/50% EU-2; and [0053] (d) 75% ZSM-12/25% EU-2,
wherein EU-2 refers to the catalyst of Example 2 and ZSM-12 refers to the catalyst of Example 1.

[0054] Thus, e.g. 25% ZSM-12/75% EU-2 means: 25% of the total dewaxing catalyst volume is occupied by the catalyst with ZSM-12 being located in the top of the stack, and 75% of the total dewaxing catalyst volume is occupied by the catalyst with EU-2 being located in the bottom of the stack.

[0055] Subsequently, a hydrogen partial pressure was applied of 140 bar and then the temperature was increased from room temperature to 125 C. at a rate of 20 oC/h, and held for two hours. The temperature was increased further to 300 oC at a rate of 50 oC/h, and held for 8 hours to ensure proper reduction of the metallic phase. The reactor was cooled to 200 C. and then the feed of Table 1 was introduced. After feed breakthrough, the temperature was increased to 250 C. in 4 hours, and held overnight. The feed of Table 1 was added at a weight hourly space velocity of 1.2 kg 1-1 h-1.

TABLE-US-00001 TABLE 1 Feed Density at 70/4 C. g/ml 0.8197 Carbon content wt. % 85.99 Hydrogen content wt. % 14.01 Sulphur content, wt. % 0.001 Nitrogen content, ppmw 0.0004 UV Aromatics Mono-aromatics wt. % 1.47 Di-aromatics wt. % 0.17 Tri-aromatics wt. % 0.09 Tetra+-aromatics wt. % 0.13 Pour Point C. 42 TBP-GLC 0.5 wt. % recovery (IBP) C. 251 10 wt. % recovery C. 358 90 wt. % recovery C. 519 98 wt. % recovery C. 568 99.5 wt. % recovery C. 595

[0056] The performance of the catalyst or catalyst stacks was evaluated at temperatures in the range between 330 C. and 350 C.

[0057] [Method: The performance of the catalyst (stack) was evaluated at temperatures in the range between 330 C. and 350 C. The performance of the catalyst (stacks) is evaluated at a pour point improvement of 75 C., which means that the product has a pour point which is 75 C. lower than the pour point of the feedstock. The pour points are measured according to ASTM D97. The feed of Table 1 was added at a weight hourly space velocity of 1.2 kg 1-1 h-1.]

[0058] The performances of the catalyst/catalyst stacks are shown in FIG. 1. In this Figure, the expression wof % stands for the wt. % on feed. C1-C4 stands for the amount of product containing 1, 2, 3, or 4 carbons. C5-150 C. stands for the amount of a hydrocarbon product with carbon number 5 up to products that have a boiling point of 150 C. 150-370 C. stands for the amount of product which has a boiling point that falls in the range between 150 and 370 C.>370 C. stands for the amount of product which has a boiling point of 370 C. or higher as measured with ASTM D2887-93. Treq.dPP 75 C. stands for the required reactor temperature to obtain a pour point (PP) improvement of 75 C.

[0059] In Table 2 the results are listed with their numerical values.

Example 4

[0060] The catalysts of Examples 1 and 2 were dried at 250 C. for 3 hours. Subsequently, a mixture of 75% of the ZSM-12 based catalyst and 25% of the EU-2(ZSM-48) based catalyst was prepared. Then the ZSM-12/EU-2(ZSM-48) catalyst mixture was mixed with 0.1 mm SiC inert material in a 1:1 vol/vol ratio to assure proper plug flow conditions and carefully loaded into a single tube test reactor of down flow mode. This happened in a similar way as in Example 3, where the catalysts were loaded on top of each other. The total catalyst volume was 20 ml. Subsequently, a hydrogen partial was applied of 140 bar and then the temperature was increased from room temperature to 125 C. at a rate of 20 oC/h, and held for two hours. The temperature was increased further to 300 oC at a rate of 50 oC/h, and held for 8 hours to ensure proper reduction of the metallic phase. The reactor was cooled to 200 C. and then the feed of Table 1 was introduced. After feed breaks through the temperature was increased to 250 C. in 4 hours, and held overnight.

[0061] The performance of the catalyst was evaluated according to the method described in Example 3. The performance of the catalyst mixture is shown in FIG. 1 next to the performance of the catalyst stacks. For an explanation of the numbers and abbreviations in the Figure, see Example 3.

[0062] In Table 2 the results are listed with their numerical

TABLE-US-00002 TABLE 2 50% EU- 25% ZSM- 50% ZSM- 75% ZSM- 75% ZSM- 100% 2/50% 100% 12/75% 12/50% 12/25% 12/25% label ZSM-12 ZSM-12 EU-2 EU-2 EU-2 EU-2 EU-2 mix Treq. dPP C. 336 338 342 339 335 332 335 75 C. Yields: C1-C4 wof % 0.5 0.8 1.1 0.8 0.7 0.6 0.7 C5-150 C. wof % 4.0 4.1 4.0 3.5 3.2 3.2 4.3 150-370 C. wof % 23.7 22.6 19.8 19.2 19.5 20.7 23.5 >370 C. wof % 71.7 72.4 75.0 76.8 76.5 75.7 71.8

CONCLUSION

[0063] It can be concluded from the performance data of Examples 3 and 4, that the stacked catalyst system of the present invention with a ZSM-12 based catalyst in the top of the stack and a EU-2 based catalyst in the bottom of the stack exhibits an enhanced performance and an improved base oil yield, not only when compared to a catalyst system containing only a EU-2 based catalyst, but also when compared to a proportionate mixture of both catalysts. Further, the stacked system of the present invention exhibits an improved base oil yield when compared to a catalyst system containing only a ZSM-12 based catalyst, whereas the performance is very well comparable to or even better than a catalyst system containing only a ZSM-12 based catalyst.