Catalyst system for dewaxing

Abstract

A catalyst system for dewaxing of a hydrocarbon feedstock comprising a mixture of a first dewaxing catalyst composition and a second dewaxing catalyst composition, wherein the first dewaxing catalyst composition is a ZSM-12 zeolite based catalyst composition and the second dewaxing catalyst composition is a EU-2 and/or ZSM-48 zeolite based catalyst composition, and wherein a concentration gradient of the mixture is achieved within a single catalyst bed, such that the concentration of the first dewaxing catalyst is decreasing and the concentration of the second dewaxing catalyst is increasing through the catalyst bed; and a process for dewaxing of a hydrocarbon feedstock comprising contacting the hydrocarbon feedstock with said catalyst system.

Claims

1. A catalyst system for dewaxing of a hydrocarbon feedstock comprising a mixture of a first dewaxing catalyst composition and a second dewaxing catalyst composition, wherein the first dewaxing catalyst composition is a ZSM-12 zeolite based catalyst composition and the second dewaxing catalyst composition is a EU-2 and/or ZSM-48 zeolite based catalyst composition, and wherein a concentration gradient of the mixture is achieved within a single catalyst bed, such that the concentration of the first dewaxing catalyst is decreasing and the concentration of the second dewaxing catalyst is increasing through the catalyst bed.

2. The catalyst system according to claim 1, wherein the catalyst bed comprises two or more separate regions in a stacked configuration, each region comprising a mixture of the first and second dewaxing catalysts, such that the regions together define a gradient decreasing in the concentration of the first dewaxing catalyst and increasing in the concentration of second dewaxing catalyst composition in a step-wise, non-linear, fashion from one region to the next region through the catalyst bed.

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

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

5. The catalyst system according to claim 1, wherein the first dewaxing catalyst and the second dewaxing catalyst each comprise a noble metal component.

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

7. The catalyst system according to 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.

8. A process for dewaxing of a hydrocarbon feedstock comprising contacting a hydrocarbon feedstock with a catalyst system according to claim 1.

9. The process according to claim 8, wherein the process takes place at a temperature from 200° C. up to 450° C. and a pressure of from 5×10.sup.5 to 200×10.sup.5 Pa.

10. The process according to claim 8, wherein the hydrocarbon 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

(1) FIG. 1 shows performance data of catalyst systems tested.

(2) The method of the invention will now be illustrated by the following non-limiting examples.

EXAMPLES

Example 1. ZSM-12 Composition

(3) 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.

(4) 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.

(5) 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(NH.sub.3).sub.4(NO.sub.3).sub.2) (3.37% wt./wt. Pt).

(6) 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

(7) Zeolite EU-2 (ZSM-48) having a SAR of 110 was prepared as described in U.S. Pat. No. 4,741,891 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.

(8) 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.

(9) 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(NH.sub.3).sub.4(NO.sub.3).sub.2) (3.3% wt./wt. Pt).

(10) 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 Comparative Single Bed and Stacked Bed Catalyst Systems

(11) The catalysts of Examples 1 and 2 were dried at 250° C. for 3 hours.

(12) 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 (“Single Bed” comparative examples).

(13) For preparing the “Stacked Bed” comparative examples, the catalysts (mixed with sufficient inert material) were loaded on top of each other into a single tube test reactor of down flow mode.

(14) In total, two “Stacked Bed” comparative examples were prepared: (a) 25% “ZSM-12”/75% “EU-2”; (b) 50% “ZSM-12”/50% “EU-2”,
wherein “EU-2” refers to the catalyst of Example 2 and “ZSM-12” refers to the catalyst of Example 1.

(15) 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.

(16) 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° C./h, and held for two hours. The temperature was increased further to 300° C. at a rate of 50° C./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.

(17) The feed of Table 1 was added at a weight hourly space velocity of 1.2 kg 1.sup.−1 h.sup.−1.

(18) 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.sup.+-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

(19) The performance of the single ZSM-12 and EU-2 catalysts and the ZSM-12/EU-2 catalyst stacks was evaluated at temperatures in the range between 330° C. and 350° C.

(20) [Method: The performance of each catalyst bed was evaluated at temperatures in the range between 330° C. and 350° C. The performance of the catalyst beds was 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.sup.−1 h.sup.−1].

(21) The performances of the single catalysts and the catalyst stacks are shown in FIG. 1.

(22) In this FIGURE, the expression “wof %” represents the wt. % on feed. “C1-C4” represents the amount of product containing 1, 2, 3, or 4 carbons. “C5-150° C.” represents the amount of a hydrocarbon product with carbon number 5 up to products that have a boiling point of 150° C. “150-370° C.” represents the amount of product which has a boiling point in the range between 150 and 370° C. “>370° C.” represents the amount of product which has a boiling point of 370° C. or higher as measured with ASTM D2887-93. “Treq.dPP 75° C.” represents for the required reactor temperature to obtain a pour point (PP) improvement of 75° C.

(23) In Table 2, the results are listed with their numerical values.

Example 4. Performance Testing of Comparative Mixed Bed Catalyst System

(24) 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° C./h, and held for two hours. The temperature was increased further to 300° C. at a rate of 50° C./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.

(25) The performance of the catalyst bed was evaluated according to the method described in Example 3.

(26) The performance of the mixed catalyst bed is shown in FIG. 1. For an explanation of the numbers and abbreviations in the FIGURE, see Example 3.

(27) In Table 2, the results are listed with their numerical values.

Example 5. Performance Testing of Catalyst System According to Present Invention

(28) Catalysts made in accordance with Examples 1 and 2 were dried at 250° C. for 3 hours.

(29) A stacked system was prepared with, in the top layer, a physical mixture of 40% of the total “ZSM-12” catalyst and 10% of the total “EU-2” catalyst and, in the bottom layer, a physical mixture of 10% of the total “ZSM-12” catalyst and 40% of the total “EU-2” catalyst. That is to say, the top layer was an 80:20 mixture of “ZSM-12” catalyst:“EU-2” catalyst and the bottom layer was a 20:80 mixture of of “ZSM-12” catalyst:“EU-2” catalyst and the overall catalyst volume ratio was 50:50.

(30) 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° C./h, and held for two hours. The temperature was increased further to 300° C. at a rate of 50° C./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.

(31) The performance of the catalyst bed was evaluated according to the method described in Example 3.

(32) The performance of the catalyst bed is shown in FIG. 1. For an explanation of the numbers and abbreviations in the FIGURE, see Example 3.

(33) In Table 2, the results are listed with their numerical values.

(34) Conclusion

(35) It can be concluded from the performance data of the Examples, that the catalyst system (i.e. the gradient mixed system) of the present invention exhibits an enhanced activity 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 mixture of both ZSM-12 and EU-2 catalysts.

(36) Further, the catalyst 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 activity is very well comparable to or even better than a catalyst system containing only a ZSM-12 based catalyst.

(37) The base oil yield of the catalyst system of the present invention is on par when compared with a stacked bed catalyst system having a ZSM-12 based catalyst in the top of the stack and a EU-2 based catalyst in the bottom of the stack, and the activity of the catalyst system of the present invention is also slightly higher.

(38) TABLE-US-00002 TABLE 2 FIG. 1 label Working Example 50% ZSM- Comparative Examples 12/50% 75% ZSM- 75% ZSM- 50% ZSM- EU-2 100% ZSM- 100% 12/25% 12/25% 12/50% gradient 12 EU-2 EU-2 EU-2 mix EU-2 mix Catalyst Bed Single Single Stacked Mixed Stacked Present Arrangement Bed Bed Bed Bed Bed Invention Treq. dPP 75° C. ° C. 336 342 332 335 335 334 Yields: C1-C4 wof % 0.5 1.1 0.6 0.7 0.7 0.8 C5-150° C. wof % 4.0 4.0 3.2 4.3 3.2 3.5 150-370° C. wof % 23.7 19.8 20.7 23.5 19.5 20.3 >370° C. wof % 71.7 75.0 75.7 71.8 76.5 75.7