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, and the promoter is selected from one or more compounds of Formula I: (I) wherein each of X and any or all of the Y'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, and the promoter is selected from one or more compounds of Formula I: ##STR00009## wherein each of X and any or all of the Y'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 catalyst is at least one aluminosilicate zeolite which comprises at least one channel having a 10-membered ring.

3. A process according to claim 2, wherein the catalyst is an aluminosilicate zeolite which comprises at least one channel having a 10-membered ring.

4. A process according to claim 1, wherein the catalyst does not comprise any aluminosilicate zeolite which comprises at least one channel having a 12-membered ring.

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

6. A process according to claim 1, wherein the zeolite is selected from framework type CHA, TON, MTT, FER, MWW, MFI, MEL, MOR, BEA and FAU.

7. A process according to claim 6, wherein the zeolite is selected from framework type FER, MWW, MFI or MEL.

8. A process according to claim 7, wherein the zeolite is selected from ferrierite, PSH-3, ZSM-5, ZSM-11, ZSM-35, and MCM-22.

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

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

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

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

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

14. A process according to claim 13, wherein X and/or any of the Y's are independently a halide substituted hydrocarbyl.

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

16. 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.

17. 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.

18. (canceled)

19. (canceled)

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

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

22. A process comprising dehydrating methanol to dimethyl ether product in the presence of a catalyst, wherein the catalyst is at least one aluminosilicate zeolite, 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 each of X and any or all of the Y'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.

23. A method of improving the productivity to dimethyl ether in a process for dehydrating methanol, the method comprising dehydrating methanol to dimethyl ether in the presence of a catalyst and a promoter, wherein the catalyst is at least one aluminosilicate zeolite, and the promoter is selected from one or more compounds of Formula I: ##STR00011## wherein each of X and any or all of the Y'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.

24. (canceled)

Description

EXAMPLES

[0090] 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-00001 TABLE 1 Framework Largest Catalyst SAR* code ring 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.

[0091] The methanol dehydration reactions of the Examples were carried out utilising the General Reaction Method and Apparatus described below.

General Reaction Method and Apparatus

[0092] 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.

[0093] 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-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

[0094] This Example demonstrates the effect of benzaldehyde 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-00002 TABLE 2 Dimethyl ether STY/g kg.sup.−1 h.sup.−1 Catalyst No Promoter Benzaldehyde (0.1 mol %) Stability SAPO-34 695 697 Good SSZ-13 912 998 Good ZSM-22 244 343 Good ZSM-23 383 456 Good Ferrierite 1521 2550 Good PSH-3 499 1955 Good ZSM-5 (23) 583 1829 Good ZSM-5 (50) 407 1888 Good ZSM-5 (280) 106 835 Good ZSM-11 345 1811 Good Mordenite 722 809 Moderate Zeolite beta 198 666 Moderate Zeolite Y 64 131 Moderate

[0095] 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

[0096] This Example demonstrates the effect of benzaldehyde concentration, mole % relative to methanol fed, on methanol dehydration reactions employing 1-, 2- and 3-dimensional zeolite catalysts where the largest ring is 10-membered. 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-00003 TABLE 3 Dimethyl ether STY/g kg.sup.−1 h.sup.−1 Benzaldehyde 0.01 0.05 0.2 0.5 Catalyst No Promoter mol % mol % mol % mol % ZSM-22 231 253 294 382 473 ZSM-23 363 381 407 469 553 Ferrierite 1619 1719 2054 2968 3875 ZSM-5 (23) 581 867 1432 2417 3387 ZSM-5 (50) 325 739 1368 2260 3057 ZSM-5 (280) 99 325 627 1051 1356

[0097] 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.

Example 3

[0098] This Example demonstrates the effect of feeding benzaldehyde and derivatives, 0.1 mole % relative to methanol fed, on methanol dehydration reactions employing a 3-dimensional 10-membered ring zeolite catalyst, ZSM-5. 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 4 below.

TABLE-US-00004 TABLE 4 Dimethyl ether STY/g kg.sup.−1 h.sup.−1 Benzaldehyde 4-Trifluoro-benzaldehyde 4-Methyl-benzaldehyde 4-Ethyl-benzaldehyde 4-n-Butyl-benzaldehyde Catalyst No Promoter 0.1 mol % 0.1 mol % 0.1 mol % 0.1 mol % 0.1 mol % ZSM-5 (23) 563 828 1712 2845 2782 3307 ZSM-5 (50) 380 836 1870 3324 3405 3893 ZSM-5 (280) 99 332 778 1714 1825 2120

[0099] 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.