Anatase polymorph titania-bound ZSM-12 zeolite composition and method of making and using such composition

Abstract

Presented is a composition useful in the catalytic dewaxing of a waxy hydrocarbon feedstock. The composition includes a mixture of ZSM-12 zeolite and titania and may further include a noble metal. The ZSM-12 zeolite preferably has a high silica-to-alumina ratio within its framework. The mixture may be dealuminated either by acid leaching using a fluorosilicate salt or by steam treating.

Claims

1. A dewaxing catalyst composition, comprising: a calcined particle, consisting essentially of ZSM-12 zeolite having a silica-to-alumina ratio of at least 50:1 and titania powder in an amount exceeding 50% anatase titania with the balance being in either in a rutile form or a brookite form or a combination of both forms and having a surface area in the range of from 10 m.sup.2/gm to 700 m.sup.2/gm, that is either acid treated or steam treated; and a noble metal component selected from the group of noble metals consisting of platinum and palladium that is incorporated into said particle after said acid treatment or said steam treatment at a noble metal concentration in the range upwardly to about 3 wt. % based on the noble metal as an element and the total dry weight of said dewaxing catalyst composition.

2. A dewaxing catalyst composition as recited in claim 1, wherein said ZSM-12 zeolite is present in said dewaxing catalyst composition in an amount of at least 10% wt. and at most 70% wt. and said titania is present in said dewaxing catalyst composition 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. A dewaxing catalyst composition as recited in claim 2, wherein said calcined particle is treated with an acid solution to thereby provide dealuminated ZSM-12 zeolite.

4. A dewaxing catalyst composition as recited in claim 3, wherein said ZSM-12 zeolite has a silica-to-alumina ratio greater than 70:1.

5. A dewaxing catalyst composition as recited in claim 1, wherein said ZSM-12 zeolite has a silica-to-alumina molar ratio greater than 70:1.

6. A dewaxing catalyst composition as recited in claim 1, wherein said calcined particle is substantially free of silica other than the silica contained in the ZSM-12 zeolite framework.

7. A dewaxing catalyst composition as recited in claim 1, wherein said mixture calcined particle is substantially free of alumina other than the alumina contained in the ZSM-12 zeolite framework.

8. A dewaxing catalyst composition as recited in claim 1, wherein said titania has a substantial absence of silica.

9. A dewaxing catalyst composition as recited in claim 1, wherein said titania has a substantial absence of alumina.

10. A dewaxing composition as recited in claim 3, wherein the acid treatment of said calcined particle with said acid solution comprises contacting said calcined particle with an aqueous solution of a fluorosilicate salt of the formula (A).sub.2/bSiF.sub.6, wherein A is a metallic or non-metallic cation other than H.sup.+ having a valence of b.

11. A dewaxing composition as recited in claim 10, wherein said aqueous solution has a pH in the range of from 2 to 8.

12. A dewaxing composition as recited in claim 11, wherein the acid treatment includes contacting said calcined particle with said aqueous solution for a contacting time period in the range of from 0.5 hours to 20 hours and at a contacting temperature in the range of from 20 C. to 100 C.

13. A process for the catalytic dewaxing of a hydrocarbon oil feed, wherein said process comprises: contacting under catalytic dewaxing conditions said hydrocarbon oil feed with the composition of claim 1.

14. A method for preparing a dewaxing catalyst composition, wherein said method comprises: preparing a formed particle that is dried and calcined to provide a calcined particle consisting essentially of ZSM-12 zeolite having a silica-to-alumina ratio of at least 50:1 and titania powder in an amount exceeding 50% anatase titania with the balance being in either in a rutile form or a brookite form or a combination of both forms and having a surface area in the range of from 10 m.sup.2/gm to 700 m.sup.2/gm; and treating said calcined particle with either steam or an acid solution to thereby provide a treated particle comprising dealuminated zeolite; and incorporating into said treated particle a noble metal selected from the group consisting of platinum and palladium at a noble metal concentration in the range upwardly to about 3 wt. % based on the metal as an element and the total dry weight of said dewaxing catalyst composition.

15. A method as recited in claim 14, wherein the treating of said calcined particle is with an acid solution to thereby provide an acid treated particle comprising dealuminated zeolite.

16. A composition prepared by the method of claim 14.

Description

(1) The following examples are presented only to illustrate certain aspects of the invention, but they are not intended to in any way be limiting.

EXAMPLE I

(2) This Example I describes the preparation of the comparative Composition A (ZSM-12/silica) and the inventive Compositions B and C (ZSM-12/titania).

(3) Composition A (Comparison)

(4) An extrudable mass was prepared by combining 25 wt % ZSM-12 zeolite having a SAR of 90, 50 wt % of amorphous precipitated silica powder (Sipernat-50 as obtained from Degussa) and 25 wt % of an ammonium stabilized commercially available silica sol (sold under the trade name Bindzil 30NH.sub.3/220 by Eka Chemicals). The weight amounts are basis dry components. The mass was extruded to give extrudates having a cylinder shape and an average diameter of 1.6 mm. These extrudates were dried at 120 C. and calcined at 625 C. for 1 hour resulting in white calcined extrudates.

(5) These extrudates were treated unstirred at a temperature of 90 C. for 5 hours with 0.02 M 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 at 120 C. for 2 hours followed by calcination at 500 C. for 1 hour.

(6) 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% w/w Pt).

(7) The impregnated composition was not washed, but equilibrated during 1.5 hours on a rolling bed, dried for 10 minutes at 180 C. (temperature incrementally increased at a rate of 15 C./minute). The temperature was raised again at an incremental rate of 30 C./minute to 290 C. (internal 270 C.) and held stable during 12 minutes. Then, the catalyst was cooled down to room temperature.

(8) Composition B (ZSM-12 Zeolite and Titania)

(9) An extrudable mass was prepared by combining 25 wt % ZSM-12 having a SAR of 90 and 75 wt % 100% anatase titania powder sold by Millenium Specialty Chemicals Inc. identified as Millenium's G5 grade titania having a nitrogen B.E.T. surface are of 293 m.sup.2/g and a bulk density of 0.56 g/ml. The weight amounts are basis dry components. The mass was extruded to give extrudates having a cylinder shape and an average diameter of 1.6 mm. These extrudates were dried at 120 C. and calcined at 625 C. for 1 hour to provide calcined extrudates.

(10) These extrudates were treated unstirred at a temperature of 90 C. for 5 hours with 0.02 M 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 at 120 C. for 2 hours followed by calcination at 500 C. for 1 hour.

(11) 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% w/w Pt).

(12) The impregnated composition was not washed, but equilibrated during 1.5 hours on a rolling bed, dried for 10 minutes at 180 C. (temperature incrementally increased at a rate of 15 C./minute). The temperature was raised again at an incremental rate of 30 C./minute to 290 C. (internal 270 C.) and held stable during 12 minutes. Then, the catalyst was cooled down to room temperature.

(13) Composition C (ZSM-12 Zeolite and Titania)

(14) This composition was prepared in the same manner as described above for Composition B with the exception that the titania powder is Degussa (Evonik) P25 80 wt % anatase and 20 wt % rutile titania.

EXAMPLE II

(15) This Example II describes the performance testing of the compositions of Example I in the catalytic dewaxing of a waxy raffinate feed and presents the results thereof.

(16) The catalyst under scrutiny was dried at 250 C. for 3 hours. Subsequently, the catalyst was mixed with sufficient inert material to assure proper plug flow conditions and loaded into a single tube test reactor of down flow mode. Subsequently, a hydrogen partial of 40 bar was applied and 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 then 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.

(17) The reactor was cooled to 200 C. and then the feed having the properties presented in Table 1 was introduced at a weight hourly space velocity of 1.0 kg feed per liter catalyst per hour, together with hydrogen at a rate of 500 Nl per kg of feed. After feed break through, the temperature was increased to 250 C. in 4 hours, and held overnight. The temperature was then adjusted to obtain a liquid product cloud point of 30 C. The cloud points were measured according to ASTM D 2500.

(18) The performance of catalysts A, B and C is shown in Table 2. The expression % w of stands for the weight percent on feed, 400 C.+ stands for product having a boiling point above 400 C. measured according to ASTM D-2887. The yield of 400 C.+ product can be considered equivalent to the base oil yield. T.sub.req is the temperature required to reach the target liquid product cloud point of 30 C.

(19) TABLE-US-00001 TABLE 1 Feed Properties Feed Density at 70/4 C. g/ml 0.7844 Carbon content % w 85.28 Hydrogen content % w 14.72 Sulphur content, ppmw <10 Nitrogen content, ppmw <1 UV Mono-aromatics Aromatics mmol/100 g 0.30 Pour Point C. +48 Cloud Point C. +56 TBP-GLC 0.5% w recovery (IBP) C. 289 10% w recovery C. 405 50% w recovery C. 461 90% w recovery C. 520 98% w recovery C. 548 99.5% w recovery C. 567

(20) TABLE-US-00002 TABLE 2 Catalyst Performance Results nC7 to iC7 @ 40% Bintulu WR conv. @ TLP PP = 30 C. T.sub.req T.sub.req ( C.), T.sub.req Yield 400 C.+ Catalyst ( C.) no AHS ( C.) (% wof) A 302 316 71.3 B 289 276 302 70.7 C 287 277 300 67.4

(21) As may be seen from the data presented in Table 2, the Catalysts B and C with the titania binder exhibits significantly better catalytic dewaxing activity than the comparative Catalyst A that uses a silica binder with the activity gain being 13 to 15 C. It is theorized that an interaction between the silica and zeolite of Catalyst A in some way impacts the catalytic activity of the composition.