Process for dehydrating alcohols to ethers

Abstract

A process for dehydrating C.sub.2+ alcohols to ether products in the presence of a catalyst and promoter, wherein the catalyst is at least one aluminosilicate zeolite catalyst which is a medium pore zeolite having a 3-dimensional framework structure, and the promoter is one or more organic carbonyl compounds or derivatives thereof, and wherein and the molar ratio of promoter to C.sub.2+ alcohols is maintained at less than 1.

Claims

1. A process comprising dehydrating C.sub.2+ alcohols to ether products in the presence of a catalyst and promoter, wherein the catalyst is at least one aluminosilicate zeolite catalyst which is a medium pore zeolite having a 3-dimensional framework structure, and the promoter is one or more organic carbonyl compounds or derivatives thereof, and wherein and the molar ratio of promoter to C.sub.2+ alcohols is maintained at less than 1.

2. A process according to claim 1, wherein the promoter is one or more compounds selected from: (i) an aldehyde of formula R.sup.A1CHO(Formula I), wherein R.sup.A1 is hydrogen, a C.sub.1-C.sub.11 alkyl group, a C.sub.3-C.sub.11 alkyl group in which 3 or more carbon atoms are joined to form a ring, or an optionally substituted aromatic group; (ii) an acetal derivative of an aldehyde of Formula I; (iii) a ketone of formula R.sup.K1COR.sup.K2 (Formula II), wherein R.sup.K1 and R.sup.K2 are identical or different and each is a alkyl group, a C.sub.1-C.sub.11 alkyl group, a C.sub.3-C.sub.11 in which 3 or more carbon atoms are joined to form a ring, or an optionally substituted aromatic group, and furthermore R.sup.K1 and R.sup.K2 together with the carbonyl carbon atom to which they are bonded may form a cyclic ketone; (iv) a ketal derivative of a ketone of Formula II; (v) an ester of formula R.sup.E1CO.sub.2R.sup.E2 (Formula III), wherein R.sup.E1 and R.sup.E2 are identical or different and are each a C.sub.1-C.sub.11 alkyl group, a C.sub.3-C.sub.11 alkyl group in which 3 or more carbon atoms are joined to form a ring, or an optionally substituted aromatic group; and (vi) a di-ester of formula R.sup.E1(CO.sub.2R.sup.E2).sub.2 (Formula IV), wherein R.sup.E1 and R.sup.E2 are identical or different and are each a C.sub.1-C.sub.11 alkyl group, a C.sub.3-C.sub.11 alkyl group in which 3 or more carbon atoms are joined to form a ring, or an optionally substituted aromatic group.

3. A process according to claim 1, wherein the aluminosilicate zeolite catalyst is a medium pore zeolite having a 3-dimensional framework structure.

4. A process according to claim 3, wherein the aluminosilicate zeolite catalyst is selected from framework types MFI and MEL.

5. A process according to claim 4, wherein the aluminosilicate zeolite catalyst is selected from ZSM-5 or ZSM-11.

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

7. A process according to claim 1, wherein the C.sub.2+ alcohols to be dehydrated are primary alcohols comprising a C.sub.2 to C.sub.6 alkyl group and a hydroxyl group.

8. A process according to claim 1, wherein the C.sub.2+ alcohols to be dehydrated is one or more alcohols selected from the group comprising ethanol, n-propanol, and n-butanol.

9. A process according to claim 1, wherein the C.sub.2+ alcohols to be dehydrated is a single C.sub.2+ alcohol species.

10. A process according to claim 1, wherein the molar ratio of promoter to C.sub.2+ alcohol is maintained in the range 0.00001:1 to 0.2:1.

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

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

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

14. A method of improving the productivity to ether products in a process for dehydrating C.sub.2+ alcohols, the method comprising dehydrating C.sub.2+ alcohols to ether products in the presence of a catalyst and a promoter, wherein the catalyst is at least one aluminosilicate zeolite catalyst which is a medium pore zeolite having a 3-dimensional framework structure, and the promoter is one or more organic carbonyl compounds or derivatives thereof, and wherein and the molar ratio of promoter to C.sub.2+ alcohols is maintained at less than 1.

15. A process comprising dehydrating C.sub.2+ alcohols to ether products in the presence of a catalyst, wherein the catalyst is at least one aluminosilicate zeolite catalyst which is a medium pore zeolite having a 3-dimensional framework structure, and wherein prior to using the catalyst in the dehydration process, the catalyst has been impregnated with a promoter which is an organic carbonyl compound or derivative thereof.

Description

EXAMPLES

(1) The ZSM-5 catalysts used in Examples 1 to 11 were obtained in ammonium-form from Zeolyst International. The ZSM-11 catalyst used in Example 12 was obtained in ammonium-form from ACS Material. The ZSM-5 and ZSM-11 catalysts were utilised in their H-form after conversion by calcination in air at 500° C.

(2) General Reaction Method and Apparatus I

(3) The ethanol dehydration reactions were carried out using a 16-channel parallel fixed-bed stainless steel reactor system. Each reactor (2 mm internal diameter) was heated to maintain a temperature of 150 or 200° C. Each reactor housed a 25 mg bed of catalyst (having particle size fraction of 100 to 200 microns diameter) loaded on top of a 6 cm deep bed of an inert material (carborundum). The reactor volume above the catalyst was also packed with carborundum. The reactor was set-up in a down-flow configuration.

(4) 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 % ethanol and inert gas was introduced into the reactor at a constant flow rate of ethanol of 13 mmol h.sup.−1 and allowed to flow through the catalyst bed for a period of at least 24 hours. Different concentrations of promoters were added to the feed in order to determine the impact on the yield of diethyl ether. The flow rate of inert gas was reduced to maintain a constant gas-hourly space velocity upon addition of the promoter and the ethanol flow rate was maintained at 13 mmol h.sup.−1.

(5) The effluent stream from each reactor was diluted with inert gas (nitrogen) and was periodically analysed by online gas chromatography to determine the yield of diethyl ether product.

(6) General Reaction Method and Apparatus II

(7) The n-hexanol dehydration reactions were carried out using a single-channel fixed-bed stainless steel reactor system. The reactor housed a 350 mg bed of ZSM-5 catalyst with a silica to alumina ratio (SAR) of 80. The catalyst had a particle size fraction of 250 to 500 microns diameter. The catalyst was loaded below a 170 mg pre-bed of inert material (silicon carbide) and above a 600 mg post-bed of inert material (silicon carbide).

(8) The reactor was maintained at a temperature of 160° C. and at a pressure of 20 barg throughout the reactions.

Example 1

(9) This Example demonstrates the effect of ethyl formate on ethanol dehydration reactions over different ZSM-5 catalysts at a reaction temperature of 150° C.

(10) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 1.

(11) TABLE-US-00001 TABLE 1 Diethyl ether STY/g kg.sup.−1 h.sup.−1 5 mol % 10 mol % 20 mol % ethyl ethyl ethyl No formate formate formate Catalyst SAR co-feed co-feed co-feed co-feed ZSM-5 23 592 1227 1567 2072 ZSM-5 80 291 1388 1839 2492 ZSM-5 280 97 605 800 1076 SAR indicates the silica:alumina molar ratio of a zeolite

(12) The results in Table 1 show that the use of ethyl formate enhances the space time yields to diethyl ether.

Example 2

(13) This Example demonstrates the effect of ethyl formate on ethanol dehydration reactions over different ZSM-5 catalysts at a reaction temperature of 200° C.

(14) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 200° C. The observed space time yields to diethyl ether product are provided in Table 2.

(15) TABLE-US-00002 TABLE 2 Diethyl ether STY/g kg.sup.−1 h.sup.−1 No 10 mol % ethyl Catalyst SAR co-feed formate co-feed ZSM-5 23 11851 15200 ZSM-5 80 8605 17274 ZSM-5 280 1634 7603 SAR indicates the silica:alumina molar ratio of a zeolite

(16) The results in Table 2 show that the use of ethyl formate enhances the space time yields to diethyl ether.

Example 3

(17) This Example demonstrates the effect of ethyl n-butyrate on ethanol dehydration reactions over different ZSM-5 catalysts.

(18) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 3.

(19) TABLE-US-00003 TABLE 3 Diethyl ether STY/g kg.sup.−1 h.sup.−1 ethyl n-butyrate co-feed No co- 0.1 1 5 10 20 Catalyst SAR feed mol % mol % mol % mol % mol % ZSM-5 23 504 510 554 666 766 1006 ZSM-5 80 317 337 469 940 1384 1904 ZSM-5 280 77 82 120 256 347 476 SAR indicates the silica: alumina molar ratio of a zeolite

(20) The results in Table 3 show that the use of ethyl n-butyrate enhances the space time yields to diethyl ether.

Example 4

(21) This Example demonstrates the effect of dimethyl adipate on ethanol dehydration reactions over different ZSM-5 catalysts.

(22) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 4.

(23) TABLE-US-00004 TABLE 4 Diethyl ether STY/g kg.sup.−1 h.sup.−1 No 0.01 mol % dimethyl Catalyst SAR co-feed adipate co-feed ZSM-5 23 499 596 ZSM-5 80 356 577 ZSM-5 280 79 159 SAR indicates the silica:alumina molar ratio of a zeolite

(24) The results in Table 4 show that the use of dimethyl adipate enhances the space time yields to diethyl ether.

Example 5

(25) This Example demonstrates the effect of 5-nonanone on ethanol dehydration reactions over different ZSM-5 catalysts.

(26) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 5.

(27) TABLE-US-00005 TABLE 5 Diethyl ether STY/g kg.sup.−1 h.sup.−1 Catalyst SAR No co-feed 0.01 mol % 5-nonanone ZSM-5 23 617 654 ZSM-5 80 299 420 ZSM-5 280 77 209 SAR indicates the silica:alumina molar ratio of a zeolite

(28) The results in Table 5 show that the use of 5-nonanone enhances the space time yields to diethyl ether.

Example 6

(29) This Example demonstrates the effect of acetone on ethanol dehydration reactions over different ZSM-5 catalysts.

(30) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 6.

(31) TABLE-US-00006 TABLE 6 Diethyl ether STY/g kg.sup.−1 h.sup.−1 Catalyst SAR No co-feed 0.01 mol % acetone ZSM-5 23 597 601 ZSM-5 80 284 296 ZSM-5 280 72 75 SAR indicates the silica:alumina molar ratio of a zeolite

(32) The results in Table 6 show that the use of acetone enhances the space time yields to diethyl ether.

Example 7

(33) This Example demonstrates the effect of 1,1-diethoxyethane on ethanol dehydration reactions over different ZSM-5 catalysts.

(34) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 7.

(35) TABLE-US-00007 TABLE 7 Dietliyl ether STY/g kg.sup.−1 h.sup.−1 No 0.05 mol % Catalyst SAR co-feed 1,1-diethoxyethane ZSM-5 23 592 648 ZSM-5 80 275 382 ZSM-5 280 67 98 SAR indicates the silica:alumina molar ratio of a zeolite

(36) The results in Table 7 show that the use of 1,1-diethoxyethane enhances the space time yields to diethyl ether.

Example 8

(37) This Example demonstrates the effect of benzaldehyde on ethanol dehydration reactions over different ZSM-5 catalysts.

(38) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 8.

(39) TABLE-US-00008 TABLE 8 Diethyl ether STY/g kg.sup.−1 h.sup.−1 No 0.01 mol % 0.1 mol % Catalyst SAR co-feed benzaldehyde benzaldehyde ZSM-5 23 573 604 903 ZSM-5 80 287 616 1836 ZSM-5 280 90 182 598 SAR indicates the silica:alumina molar ratio of a zeolite

(40) The results in Table 8 show that the use of benzaldehyde enhances the space time yields to diethyl ether.

Example 9

(41) This Example demonstrates the effect of n-butanal on ethanol dehydration reactions over different ZSM-5 catalysts.

(42) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 9.

(43) TABLE-US-00009 TABLE 9 Diethyl ether STY/g kg.sup.−1 h.sup.−1 No 0.01 mol % 0.1 mol % Catalyst SAR co-feed n-butanal n-butanal ZSM-5 23 544 558 567 ZSM-5 80 281 309 423 ZSM-5 280 73 88 140 SAR indicates the silica:alumina molar ratio of a zeolite

(44) The results in Table 9 show that the use of n-butanal enhances the space time yields to diethyl ether.

Example 10

(45) This Example demonstrates the effect of benzaldehyde on n-hexanol dehydration reactions over a ZSM-5 catalyst.

(46) The n-hexanol dehydration reactions were carried out using the General Reaction Method and Apparatus II described above. A liquid feed was introduced into the reactor at a constant flow rate of 0.08 ml min.sup.−1 to achieve a liquid hourly space velocity (LHSV) of 10 mL mL.sub.cat.sup.−1 h.sup.−1. The reactor was set-up in a down-flow configuration. A liquid sample was analysed by an off-line gas chromatography (GC) at 3.5 h time on stream (ToS).

(47) At 3.5 h ToS the liquid feed was changed to one consisting of 1 mol % benzaldehyde (1.06 g) in n-hexanol (101.14 g); all other variables remained the same. At 5.5 h ToS a liquid sample was analysed by off-line GC. The observed space time yields to dihexyl ether and hexene products are provided in Table 10.

(48) TABLE-US-00010 TABLE 10 STY/g kg.sup.−1 h.sup.−1 No co-feed 1 mol % benzaldehyde co-feed Product (ToS = 3.5 h) (ToS = 5.5 h) Hexene 86 73 Dihexyl ether 287 360

(49) The results in Table 10 show that the use of benzaldehyde enhances the space time yield to dihexyl ether.

Example 11

(50) This Example demonstrates the effect of 4-trifluorobenzaldehyde on n-hexanol dehydration reactions over a ZSM-5 catalyst.

(51) The n-hexanol dehydration reactions were carried out using the General Reaction Method and Apparatus II described above. A liquid feed was introduced into the reactor at a constant flow rate of 0.08 ml min.sup.−1 to achieve a liquid hourly space velocity (LHSV) of 10 mL mL.sub.cat.sup.−1 h.sup.−1. The reactor was set-up in a down-flow configuration. A liquid sample was analysed by an off-line gas chromatography (GC) at 4.25 h time on stream (ToS).

(52) At 4.25 h ToS the liquid feed was changed to one consisting of 1 mol % 4-fluorobenzaldehyde (1.746 g) in n-hexanol (101.14 g); all other variables remained the same. At 6.25 h ToS a liquid sample was analysed by off-line GC. The observed space time yields to dihexyl ether and hexene products are provided in Table 11.

(53) TABLE-US-00011 TABLE 11 STY/g kg.sup.−1 h.sup.−1 No co-feed 1 mol % 4-trifluorobenzaldehyde Product (ToS = 4.25 h) co-feed (ToS = 6.25 h) Hexene 58 44 Dihexyl ether 287 312

(54) The results in Table 11 show that the use of 4-trifluorobenzaldehyde enhances the space time yield to dihexyl ether.

Example 12

(55) This Example demonstrates the effect of ethyl formate on ethanol dehydration reactions over ZSM-5 and ZSM-11 catalysts at a reaction temperature of 150° C.

(56) The ethanol dehydration reactions were carried out using the General Reaction Method and Apparatus I described above at a reaction temperature of 150° C. The observed space time yields to diethyl ether product are provided in Table 12.

(57) TABLE-US-00012 TABLE 12 Diethyl ether STY/g kg.sup.−1 h.sup.−1 No 5 mol % ethyl Catalyst SAR co-feed formate co-feed ZSM-5 50 376 1435 ZSM-11 50 372 1381 SAR indicates the silica:alumina molar ratio of a zeolite

(58) The results in Table 12 show that the use of ethyl formate enhances the space time yields to diethyl ether.