PROCESS

Abstract

A process for dehydrating methanol to dimethyl ether product in the presence of a catalyst and a promoter, wherein the catalyst is at least one aluminosilicate zeolite, wherein:—the aluminosilicate zeolite is selected from: (i) a zeolite having a 2-dimensional framework structure comprising at least one channel having a 10-membered ring, and having a maximum free sphere diameter of at least 4.8 Angstroms; (ii) a zeolite having a 3-dimensional framework structure comprising at least one channel having a 10-membered ring; or (iii) a zeolite comprising at least one channel having a 12-membered ring;—the promoter is selected from one or more compounds of Formula I: (I) wherein Y is selected from a C.sub.1-C.sub.4 hydrocarbyl substituent, and wherein each of X and any or all of the Z's may independently be selected from hydrogen, halide, a substituted or unsubstituted hydrocarbyl substituent, or a compound of the formula —CHO, —CO.sub.2R, —COR, or —OR, where R is hydrogen or a substituted or unsubstituted hydrocarbyl substituent, and wherein the molar ratio of promoter to methanol is maintained at less than 1.

##STR00001##

Claims

1. A process comprising dehydrating methanol to dimethyl ether product in the presence of a catalyst and a promoter, wherein the catalyst is at least one aluminosilicate zeolite, wherein: the aluminosilicate zeolite is selected from: (i) a zeolite having a 2-dimensional framework structure comprising at least one channel having a 10-membered ring, and having a maximum free sphere diameter of at least 4.8 Angstroms; (ii) a zeolite having a 3-dimensional framework structure comprising at least one channel having a 10-membered ring; or (iii) a zeolite comprising at least one channel having a 12-membered ring; the promoter is selected from one or more compounds of Formula I: ##STR00009## wherein Y is selected from a C.sub.1-C.sub.4 hydrocarbyl substituent, and wherein each of X and any or all of the Z's may independently be selected from hydrogen, halide, a substituted or unsubstituted hydrocarbyl substituent, or a compound of the formula —CHO, —CO.sub.2R, —COR, or —OR, where R is hydrogen or a substituted or unsubstituted hydrocarbyl substituent, and wherein the molar ratio of promoter to methanol is maintained at less than 1.

2. A process according to claim 1, wherein the zeolite is a H-form zeolite.

3. A process according to claim 1, wherein the zeolite is selected from framework type MWW, MFS, TER, MFI, and MEL.

4. A process according to claim 1, wherein the zeolite is selected from framework type MWW, MEL, MFI, BEA, MOR, or FAU.

5. A process according to claim 1, wherein the zeolite is selected from zeolite Y, mordenite, zeolite beta, ZSM-5, ZSM-11, PHS-3, and MCM-22.

6. A process according to claim 1, wherein the zeolite is composited with a binder material.

7. A process according to claim 1, wherein Y is selected from methyl, ethyl, n-propyl, or n-butyl, preferably selected from methyl or ethyl, such as methyl.

8. A process according to claim 1, wherein X and/or any of the Z's are independently selected from hydrogen, halide, or substituted or unsubstituted hydrocarbyl substituent comprising from 1 to 11 carbon atoms.

9. A process according to claim 1, wherein X and/or any of the Z's are independently selected from a substituted or unsubstituted hydrocarbyl substituent.

10. A process according to claim 9, wherein X and/or any of the Z's are independently selected from an unsubstituted hydrocarbyl substituent comprising from 1 to 11 carbon atoms.

11. A process according to claim 9, wherein X and/or any of the Z's are independently selected from a substituted hydrocarbyl substituent comprising from 1 to 11 carbon atoms.

12. A process according to claim 11, wherein X and/or any of the Z's are independently a halide substituted hydrocarbyl.

13. A process according to claim 1, wherein all of the Z's are hydrogen.

14. A process according to claim 1, wherein the total amount of promoter relative to methanol is maintained in an amount of at least 1 ppm.

15. A process according to claim 1, wherein the molar ratio of promoter to methanol is maintained in the range 0.00001:1 to 0.2:1.

16. A process according to claim 1, wherein the promoter is added to the dehydration process.

17. A process according to claim 1, wherein the promoter is generated in-situ in the dehydration process.

18. A process according to claim 1, wherein the process is carried out at a temperature of from 100° C. to 300° C.

19. A process according to claim 1, wherein the process is carried out as a heterogeneous vapour phase process.

20. A process comprising dehydrating methanol to dimethyl ether product in the presence of a catalyst, wherein the catalyst is at least one aluminosilicate zeolite, wherein: the aluminosilicate zeolite is selected from: (i) a zeolite having a 2-dimensional framework structure comprising at least one channel having a 10-membered ring, and having a maximum free sphere diameter of at least 4.8 Angstroms; (ii) a zeolite having a 3-dimensional framework structure comprising at least one channel having a 10-membered ring; or (iii) a zeolite comprising at least one channel having a 12-membered ring; and wherein prior to using the catalyst in the dehydration process, the catalyst has been impregnated with a promoter is selected from one or more compounds of Formula I: ##STR00010## wherein Y is selected from a C.sub.1-C.sub.4 hydrocarbyl substituent, and wherein each of X and any or all of the Z's may independently be selected from hydrogen, halide, a substituted or unsubstituted hydrocarbyl substituent, or a compound of the formula —CHO, —CO.sub.2R, —COR, or —OR, where R is hydrogen or a substituted or unsubstituted hydrocarbyl substituent.

21. A method of improving the productivity to dimethyl ether product in a process for dehydrating methanol, the method comprising dehydrating methanol in the presence of a catalyst and a promoter, wherein the catalyst is at least one aluminosilicate zeolite, wherein: the aluminosilicate zeolite is selected from: (i) a zeolite having a 2-dimensional framework structure comprising at least one channel having a 10-membered ring, and having a maximum free sphere diameter of at least 4.8 Angstroms; (ii) a zeolite having a 3-dimensional framework structure comprising at least one channel having a 10-membered ring; or (iii) a zeolite comprising at least one channel having a 12-membered ring; the promoter is selected from one or more compounds of Formula I: ##STR00011## wherein Y is selected from a C.sub.1-C.sub.4 hydrocarbyl substituent, and wherein each of X and any or all of the Z's may independently be selected from hydrogen, halide, a substituted or unsubstituted hydrocarbyl substituent, or a compound of the formula —CHO, —CO.sub.2R, —COR, or —OR, where R is hydrogen or a substituted or unsubstituted hydrocarbyl substituent, and wherein the molar ratio of promoter to methanol is maintained at less than 1.

22. (canceled)

Description

EXAMPLES

[0098] The zeolites and SAPO used in the Examples were utilised in their H-form. The SAPO-34, ferrierite, PSH-3, ZSM-5 mordenite, beta and Y catalysts were obtained from Zeolyst International and the SSZ-13 and ZSM-11 were obtained from ACS Materials. These catalysts were calcined in air at 500° C. for 4 hours prior to use. The ZSM-22 and ZSM-23 was prepared in accordance with literature methods. Details of the zeolites is provided in Table 1 below.

TABLE-US-00002 TABLE 1 Framework Largest ring Catalyst SAR* code size Structure** SAPO-34 n/a CHA 8 3-D SSZ-13 18 CHA 8 3-D ZSM-22 61 TON 10 1-D ZSM-23 91 MTT 10 1-D Ferrierite 20 FER 10 2-D PSH-3 21 MWW 10 2-D ZSM-5 (23) 23 MFI 10 3-D ZSM-5 (50) 50 MFI 10 3-D ZSM-5 (280) 280 MFI 10 3-D ZSM-11 53 MEL 10 3-D Mordenite 20 MOR 12 1-D Zeolite beta 25 BEA 12 3-D Zeolite Y 30 FAU 12 3-D *SAR indicates the silica to alumina molar ratio of a zeolite. **1-D, 2-D and 3-D indicate a 1-dimensional, a 2-dimensional and a 3-dimensional zeolite framework structure respectively.

[0099] The methanol dehydration reactions of the Examples were carried out utilising the General Reaction Method and Apparatus described below.

General Reaction Method and Apparatus

[0100] The methanol dehydration reactions were carried out using a 16-channel parallel fixed-bed stainless steel reactor system. Each reactor (10 mm internal diameter) housed a bed of catalyst mixed with silica dioxide diluent (0.168 g catalyst diluted with 0.337 g silica dioxide). The catalyst and silica dioxide each had a particle size of 450 to 900 microns diameter. The mixture was loaded on top of a 6.5 cm deep bed of an inert material (quartz sand). The reactor volume above the catalyst bed was also packed with quartz sand.

[0101] Each reactor was maintained at a temperature of 150° C. and at a total pressure of 1100 kPa throughout the reactions. A gaseous feed comprising 10 mol % methanol and inert gas was introduced into the reactor and allowed to flow through the catalyst bed for at least 24 hours before a promoter compound was added to the feed. Throughout the reactions the methanol feed rate was kept constant at 45 mmol h.sup.−1. The effluent stream from each reactor was cooled to 5° C. in a condenser and the gas phase from the condenser was periodically analysed by online gas chromatography to determine the yield of dimethyl ether product. Different promoters were added to the feed and the dimethyl ether yield was measured. When introducing the promoter the flow rate of inert gas was adjusted to maintain a constant GHSV of the combined MeOH, promoter and inert gas feed.

Example 1

[0102] This Example demonstrates the effect of acetophenone co-feed at 0.1 mol % relative to methanol fed, on methanol dehydration reactions employing various catalysts. The methanol dehydration reactions were carried out using the General Reaction Method and Apparatus described above. The observed space time yields to dimethyl ether product are provided in Table 2 below.

TABLE-US-00003 TABLE 2 Dimethyl ether STY/g kg.sup.−1 h.sup.−1 Acetophenone Catalyst No Promoter (0.1 mol %) Stability SAPO-34 652 666 Good SSZ-13 829 847 Good ZSM-22 232 246 Good ZSM-23 356 371 Good Ferrierite 1375 1401 Good PSH-3 398 606 Good ZSM-5 (23) 525 697 Good ZSM-5 (50) 410 597 Good ZSM-5 (280) 96 195 Good ZSM-11 320 555 Good Mordenite 665 995 Moderate Zeolite beta 186 1443 Moderate Zeolite Y 45 61 Moderate

[0103] Some catalysts had moderate stability during introduction of the catalyst co-feed and the percentage decrease in DME STY over a 12-hour period during addition of the co-feed was greater than 5%. The DME STY with no promoter is taken immediately before the promoter was added. The DME STY with the co-feed over the catalysts with good stability is representative of the DME productivity observed during the co-feed period. For the catalysts with moderate stability the DME STY with the co-feed is the maximum DME productivity observed during the co-feed period.

Example 2

[0104] This Example demonstrates the effect of feeding acetophenone and derivatives, 0.1 mole % relative to methanol fed, on methanol dehydration reactions. The methanol dehydration reactions were carried out using the General Reaction Method and Apparatus described above. The observed space time yields to dimethyl ether product are provided in Table 3 below.

TABLE-US-00004 TABLE 3 Dimethyl ether STY/g kg.sup.−1 h.sup.−1 4-Trifluoro- 4-Methyl- 4-Ethyl- 4-n-Butyl- No Acetophenone acetophenone acetophenone acetophenone acetophenone Catalyst Promoter 0.1 mol % 0.1 mol % 0.1 mol % 0.1 mol % 0.1 mol % ZSM-5 (23) 558 697 583 743 782 922 ZSM-5 (50) 377 597 436 855 1021 1379 ZSM-5 (280) 100 195 121 477 551 703 ZSM-11 317 555 391 727 847 1199

[0105] The DME STY with no promoter is taken immediately before the promoter was first added. The DME STY with the co-feed is representative of the DME productivity observed during the co-feed period.