PROCESS FOR DEHYDRATION OF OXYGENATES WITH HETEROPOLYACID CATALYSTS HAVING MIXED OXIDE SUPPORTS AND USE OF THE SAME

Abstract

The present invention relates to a process for producing ethene by the vapour phase dehydration of ethanol using a supported heteropolyacid catalyst. In particular, the present invention involves the use of a supported heteropolyacid catalyst, wherein the supported heteropolyacid catalyst is: i) a mixed oxide support comprising silica and a transition metal oxide, wherein silica is present in an amount of at least 50 wt. %, based on the weight of the mixed oxide support; or ii) a mixed oxide support comprising zirconia and a different transition metal oxide, wherein zirconia is present in an amount of at least 50 wt. %, based on the weight of the mixed oxide support. When used in a process for the preparation of ethene by vapour phase dehydration, and after attaining steady-state performance of the catalyst, the process may be operated continuously with the same supported heteropolyacid catalyst for at least 150 hours without any regeneration of the catalyst.

Claims

1. A process for the vapour phase chemical dehydration of ethanol in a reactor in the presence of a supported heteropolyacid catalyst, wherein the support of the supported heteropolyacid catalyst is: i) a mixed oxide support comprising silica and a transition metal oxide, wherein silica is present in an amount of at least 50 wt. %, based on the weight of the mixed oxide support; or ii) a mixed oxide support comprising zirconia and a different transition metal oxide, wherein zirconia is present in an amount of at least 50 wt. %, based on the weight of the mixed oxide support; and wherein, after attaining steady-state performance of the catalyst, said process is operated continuously with the same supported heteropolyacid catalyst for at least 150 hours, without any regeneration of the catalyst.

2. A process according to claim 1, wherein, after attaining steady-state performance of the catalyst, the process is operated continuously with the same supported heteropolyacid catalyst for at least 200 hours, preferably at least 250 hours, without any regeneration of the catalyst.

3. A process according to claim 1 or claim 2, wherein the catalyst retains at least 25%, preferably at least 50%, more preferably at least 75% and even more preferably at least 85% of its maximum activity, observed for the operating temperature under steady-state conditions, after at least 200 hours of operation of the process.

4. A process according to any of claims 1 to 3, wherein the support is a mixed oxide support comprising silica and a transition metal oxide, preferably comprising at least 60 wt. % silica.

5. A process according to any of claims 1 to 3, wherein the support is a mixed oxide support comprising zirconia and a different transition metal oxide, preferably comprising at least 60 wt. % zirconia.

6. A process according to any of the preceding claims, wherein the transition metal oxide is selected from an oxide of a Group 3 to 6 metal, preferably an oxide of Sc, Y, La, Ti, Zr, Hf, Nb, Ta or W.

7. A process according to claim 4, wherein the transition metal oxide is an oxide of Nb, Ti, Zr or W, preferably an oxide of Nb, Ti, or Zr, more preferably an oxide of Ti or Zr.

8. A process according to claim 5, wherein the different transition metal oxide is an oxide of W, Ti, Nb, Y or La, preferably an oxide of W, Nb or Ti, more preferably an oxide of Nb or Ti.

9. A process according to any of the preceding claims, wherein the transition metal oxide is present in the mixed oxide support in an amount from 1 to 40 wt. %, preferably from 2 to 35 wt. %.

10. A process according to any of the preceding claims, wherein the heteropolyacid catalyst is a phosphotungstic or a silicotungstic acid, preferably a silicotungstic acid.

11. A process according to any of the preceding claims, wherein the feed temperature of the feed-stream comprising ethanol is from 180° C. to 270° C., more preferably from 190° C. to 260° C., and most preferably from 200° C. to 260° C.

12. A process according to any of the preceding claims, wherein the process is operated at an internal reactor pressure of from 0.1 MPa to 4.5 MPa, more preferably at a pressure of from 1.0 MPa to 3.5 MPa.

13. Use of a supported heteropolyacid catalyst comprising a mixed oxide support for increasing catalyst lifetime in a monohydric alcohol dehydration process wherein the supported heteropolyacid catalyst comprises i) a mixed oxide support comprising silica and a transition metal oxide, wherein silica is present in an amount of at least 50 wt. %, based on the weight of the mixed oxide support; or ii) a mixed oxide support comprising zirconia and a different transition metal oxide, wherein zirconia is present in an amount of at least 50 wt. %, based on the weight of the mixed oxide support

14. A use according to claim 12, wherein the supported heteropolyacid catalyst is as defined in any of claims 4 to 10.

15. A use according to claim 13 or claim 14, wherein the monohydric alcohol dehydration process is an ethanol dehydration process, preferably an ethanol dehydration process operated according to the conditions of claims 1, 2, 11 or 12.

Description

[0061] The present invention will now be illustrated by way of the following examples and with reference to the following figures:

[0062] FIG. 1: A comparison of results of the vapour phase dehydration of ethanol using catalysts B, F, G, H, I J, K, L, M and AB (Experiments Nos. 1, 3, 4, 8, 11, 13, 15, 16, 20, 21, 22, 32 from Table 3);

[0063] FIG. 2: A comparison of results of the vapour phase dehydration of ethanol using catalysts B, N, O, P, Q, R, S, T, U (Experiments Nos. 1, 7, 9, 11, 12, 14, 19, 23, 24 and 25 from Table 3);

[0064] FIG. 3: A comparison of results of the vapour phase dehydration of ethanol using catalysts B, M, V and W (Experiments Nos. 1, 5, 8, 11 and 18 from Table 3);

[0065] FIG. 4: A comparison of results of the vapour phase dehydration of ethanol using catalysts B, X, Y, Z and AA (Experiments Nos. 1, 2, 6, 10, 11 and 17 from Table 3);

[0066] FIG. 5: A comparison of results of the vapour phase dehydration of ethanol using catalysts B, D and E (Experiments Nos. 1, 11, 26 and 27 from Table 3);

[0067] FIG. 6: A comparison of results of the vapour phase dehydration of ethanol using catalysts A and B (Experiments Nos. 28 and 29 from Table 3); and

[0068] FIG. 7: A comparison of results of the vapour phase dehydration of ethanol using catalysts B and C (Experiments Nos. 30 and 31 from Table 3).

EXAMPLES

Preparation of Supported Heteropolyacid Catalyst (Supported Silicotungstic Acid Catalyst)

[0069] Table 1 below lists the supports that were used for the preparation of the supported silicotungstic acid catalysts used in the Examples.

TABLE-US-00001 TABLE 1 Support Description/Type Silica - Grace Davison G57 Silica - Aerolyst 3045 Silica - Cariact Q15 Alumino-silicate Silica doped with Alumina (7%) Silica-Alumina (25%) γ-Alumina Silica with Niobia (10%) Silica-Titania Cogel (3% TiO.sub.2, enriched in shell of SiO.sub.2) Silica-Titania Cogel (3% TiO.sub.2, dispersed homogeneously throughout SiO.sub.2) Silica doped with Titania (5%) Silica-Titania (32%) Silica-Titania (51%) Silica-Titania (70%) Titania (100% with 75% anatase phase) m/t-Zirconia-Titania (41% anatase phase) Silica-Zirconia Cogel (3% ZrO.sub.2, enriched in shell of SiO.sub.2) Silica with monoclinic-Zirconia (10%) Silica doped with Zirconia (5%) monoclinic-Zirconia (95%+) tetragonal-Zirconia (95%+) Tungstated tetragonal-Zirconia (18% WO.sub.3) Carbon (93%+)

[0070] Silicotungstic acid hydrate was dissolved in water and then a support according to Table 1 was added to this solution (which was always in excess of the pore volume and voidage of the support). The mass of each reagent is given in Table 2 below. The support was allowed to contact the solution for at least 1 hour with occasional gentle swirling to dislodge any trapped air bubbles before the excess solution was drained, under gravity, from the support. The catalyst was allowed to drain for between 15 to 60 minutes until no more liquid was removed from the support. After draining was complete, the catalyst was transferred to a ceramic tray and dried in an oven at between 110° C. and 130° C. to give the dried solid catalyst.

[0071] The dried solid catalyst was weighed and the amount of silicotungstic acid adsorbed on the catalyst calculated by difference in weight to the starting support material as indicated in Table 2.

TABLE-US-00002 TABLE 2 Mass of Dried STA Support Water catalyst Loading Catalyst Example Support (g) STA (g) (g) (g) (g/kg) A Comparative Silica - Aerolyst 3045 30.01 14.91 73.28 34.76 136.6 B Comparative Silica - Aerolyst 3045 512.00 508.00 1249.00 678.35 245.2 C Comparative Silica - Aerolyst 3045 458.39 913.40 1123.00 735.30 376.6 D Comparative Silica - Cariact Q15 430.00 430.00 976.00 591.37 272.7 E Comparative Silica - Grace Davison G57 20.05 21.54 49.13 27.77 278.0 F Comparative monoclinic-Zirconia 15.90 4.58 16.52 18.43 137.3 (95%+) G Comparative tetragonal-Zirconia (95%+) 15.17 9.12 20.07 18.89 196.9 H Example m/t-Zirconia-Titania (41% 15.34 8.11 20.10 18.60 175.3 anatase phase) I Example Silica with monoclinic- 10.02 5.73 25.10 12.90 223.3 Zirconia (10%) J Example Silica doped with Zirconia 10.07 8.11 25.02 13.25 240.0 (5%) K Example Silica-Zirconia Cogel (3% 10.20 16.22 21.94 20.83 510.3 ZrO.sub.2, enriched in shell of SiO.sub.2) L Example Silica-Zirconia Cogel (3% 10.00 8.14 22.00 15.24 343.8 ZrO.sub.2, enriched in shell of SiO.sub.2) M Example Tungstated tetragonal- 14.48 4.50 16.10 16.15 103.2 Zirconia (18% WO.sub.3) N Comparative Titania (100% with 75% 8.02 2.04 2.93 9.81 181.8 anatase phase) O Example Silica-Titania Cogel (3% 5.02 3.32 11.50 7.31 313.3 TiO.sub.2, enriched in shell of SiO.sub.2) P Example Silica-Titania Cogel (3% 4.98 7.58 11.03 11.26 557.7 TiO.sub.2, enriched in shell of SiO.sub.2) Q Example Silica-Titania Cogel (3% 5.06 5.04 11.66 7.71 343.5 TiO.sub.2, dispersed homogeneously throughout SiO.sub.2) R Example Silica doped with Titania 10.13 6.89 25.00 12.97 219.0 (5%) S Example Silica-Titania (32%) 10.03 9.73 25.11 13.19 239.6 T Comparative Silica-Titania (51%) 10.05 10.01 25.07 12.89 220.3 U Comparative Silica-Titania (70%) 10.23 7.64 25.03 12.37 173.0 V Example Silica-Niobia (10%) 10.10 5.89 25.28 13.20 234.8 W Comparative Carbon (93%+) 4.49 4.60 20.42 6.54 313.9 X Comparative γ-Alumina 8.08 1.99 10.00 9.38 138.9 Y Comparative Silica-Alumina (25%) 10.07 10.11 23.03 13.54 256.3 Z Comparative Silica doped with Alumina 10.02 6.32 25.11 12.16 176.0 (7%) AA Comparative Alumino-silicate 30.32 46.71 50.53 42.68 289.6 AB Example Tungstated tetragonal- 30.17 27.55 32.26 39.43 234.8 Zirconia (18% WO.sub.3)
General Procedure for Vapour Phase Dehydration of Ethanol with Supported Silicotungstic Acid

[0072] A mass of supported silicotungstic acid catalyst (as indicated in Table 3 below) prepared in accordance with the above method was loaded into a reactor tube having an isothermal bed and pressurised to 0.501 MPa under inert gas (nitrogen and helium) flow. The catalyst was heated at 2° C./min to 240° C. under a combined nitrogen (0.01500 mol/hr) and helium (0.00107 mol/hr) flow and held at this temperature for 8 hours before being cooled to 150° C.

[0073] Ethanol (0.04084 mol/hr) was then added to the nitrogen/helium flow and the temperature was increased at 2° C./min to 225° C. Once at 225° C. the feed pressure was increased at a rate of 0.1 MPa/min such that the pressure inside the reactor was increased to the value of 27.57 MPa. Once at the desired pressure diethyl ether and water were added to the ethanol, helium and nitrogen flow and the flows of the feed components adjusted to give ethanol (0.02677 mol/hr), diethyl ether (0.00776 mol/hr), water (0.00297 mol/hr), helium (0.00106 mol/hr) and nitrogen (0.01479 mol/hr).

[0074] Once the catalyst performance had stabilised to a steady-state at 225° C., typically after around 100 hrs, the catalyst temperature, which is the same as the feed temperature in this particular reactor, was increased to 260° C. and the ethylene productivity monitored versus time by on-line GC analysis.

TABLE-US-00003 TABLE 3 Mass of catalyst STA in STA in Expt. Loading Reactor Reactor No. Plate Catalyst Support (g/kg) (mg) (mg) 1 5 B Silica - Aerolyst 3045 245.2 54.34 13.5 2 5 X γ-Alumina 138.9 98.9 13.7 3 5 F monoclinic-Zirconia (95%+) 137.3 100.09 13.7 4 5 L Silica-Zirconia Cogel (3% ZrO.sub.2, enriched in shell 343.8 40 13.8 of SiO.sub.2) 5 5 W Carbon (93%+) 313.9 43.77 13.7 6 5 Y Silica-Alumina (25%) 256.3 53.6 13.7 7 5 Q Silica-Titania Cogel (3% TiO.sub.2, dispersed 343.5 40.01 13.7 homogeneously throughout SiO2) 8 5 M Tungstated tetragonal-Zirconia (18% WO.sub.3) 103.2 133.1 13.7 9 5 O Silica-Titania Cogel (3% TiO.sub.2, enriched in shell of 313.3 43.91 13.8 SiO.sub.2) 10 7 AA Alumino-silicate 289.6 47.4 13.7 11 7 B Silica - Aerolyst 3045 245.2 54.3 13.5 12 7 N Titania (100% with 75% anatase phase) 181.8 75.6 13.7 13 7 F monoclinic-Zirconia (95%+) 137.3 100.1 13.7 14 7 P Silica-Titania Cogel (3% TiO.sub.2, enriched in shell of 557.7 24.6 13.7 SiO.sub.2) 15 7 K Silica-Zirconia Cogel (3% ZrO.sub.2, enriched in shell 510.3 27 13.8 of SiO.sub.2) 16 7 J Silica doped with Zirconia (5%) 240.0 57.3 13.8 17 7 Z Silica doped with Alumina (7%) 176.0 78.2 13.8 18 7 V Silica with Niobia (10%) 234.8 58.5 13.7 19 7 R Silica doped with Titania (5%) 219.0 62.7 13.7 20 7 I Silica with monoclinic-Zirconia (10%) 223.3 61.6 13.8 21 7 H m/t-Zirconia-Titania (41% anatase phase) 175.3 78.4 13.7 22 7 G tetragonal-Zirconia (95%+) 196.9 69.9 13.8 23 7 S Silica-Titania (32%) 239.6 57.4 13.8 24 7 T Silica-Titania (51%) 220.3 62.5 13.8 25 7 U Silica-Titania (70%) 173.0 79.5 13.8 26 5 D Silica - Cariact Q15 272.7 50.44 13.8 27 5 E Silica - Grace Davison G57 278.0 49.44 13.7 28 1 B Silica - Aerolyst 3045 245.2 54.3 13.5 29 1 A Silica - Aerolyst 3045 136.6 94.9 13.3 30 1 C Silica - Aerolyst 3045 376.6 49.1 18.5 31 1 B Silica - Aerolyst 3045 245.2 81.4 20.2 32 7 AB Tungstated tetragonal-Zirconia (18% WO.sub.3) 234.8 58.6 13.8

Example 1

[0075] Vapour phase dehydration of ethanol was conducted independently with catalysts B, F, G, H, I J, K, L, M and AB (Experiments Nos. 1, 3, 4, 8, 11, 13, 15, 16, 20, 21, 22, 32 from Table 3) according to the above procedure. These results of the reactions are illustrated graphically in FIG. 1.

[0076] The results show the benefit of using a mixed oxide support in accordance with the present invention for extending the heteropolyacid catalyst lifetime and reducing catalyst deactivation. Catalysts H, I, J, K, L and M employed in Experiments 4, 8, 15, 16, 20 and 21 according to Table 3, which includes catalysts comprising silica supports modified with zirconia (Catalysts I to L), a zirconia support modified by titania (Catalyst H) or a tungstated zirconia support (Catalyst M) in accordance with the invention, retain higher levels of ethylene productivity over the course of the reactions than Catalysts B, F and G employed in Experiments 1, 3, 11, 13 and 22, which include single oxide supports of silica or zirconia.

[0077] Moreover, it is also apparent that supported catalysts according to the present invention retain well over 25% of their maximum activity, observed for the same operating conditions, even after 200 hours of operation of the process with the same catalyst under the same conditions without regeneration.

[0078] It can also be seen that the initial ethylene productivity of a catalyst comprising a zirconia support is improved by modifying with titania, as illustrated by a comparison of the initial ethylene productivities of Catalyst H (Experiment 21) and Catalysts F and G (Experiments 3, 13 and 22).

Example 2

[0079] Vapour phase dehydration of ethanol was conducted independently with catalysts B, N, O, P, Q, R, S, T, U (Experiments Nos. 1, 7, 9, 11, 12, 14, 19, 23, 24 and 25 from Table 3) according to the above procedure. The results of the reactions are illustrated graphically in FIG. 2.

[0080] The results show the benefit of using a mixed oxide support in accordance with the present invention for extending the heteropolyacid catalyst lifetime and reducing catalyst deactivation. Catalysts O, P, Q, R and S employed in Experiments 7, 9, 14, 19 and 23 according to Table 3, which includes catalysts comprising silica supports modified with less than 50 wt. % titania (Catalysts O to S) retain higher levels of ethylene productivity over the course of the reactions than Catalysts B, N, T and U employed in Experiments 1, 11, 12, 24 and 25, which include single oxide supports of silica (Catalysts B and N) or silica-titania supports comprising less than 50 wt. % silica (Catalysts T and U).

[0081] Moreover, it is also apparent that supported catalysts according to the present invention retain well over 25% of their maximum activity, observed for the same operating conditions, even after 200 hours of operation of the process with the same catalyst under the same conditions and without regeneration.

Example 3

[0082] Vapour phase dehydration of ethanol was conducted independently with catalysts B, M, V and W (Experiments Nos. 1, 5, 8, 11 and 18 from Table 3) according to the above procedure. The results of the reactions are illustrated graphically in FIG. 3.

[0083] The results show the benefit of using a mixed oxide support in accordance with the present invention for extending the heteropolyacid catalyst lifetime and reducing catalyst deactivation. Catalysts M and V employed in Experiments 8 and 18 according to Table 3, which includes catalysts comprising a zirconia support modified with tungsten oxide (Catalyst M) or a silica support modified with niobia (Catalyst V) retain higher levels of ethylene productivity over the course of the reactions than Catalysts B and W employed in Experiments 1, 5 and 11, which include single oxide supports of silica (Catalyst B) or carbon (Catalyst W).

[0084] Moreover, it is also apparent that supported catalysts according to the present invention retain well over 25% of their maximum activity, observed for the same operating conditions, even after 200 hours of operation of the process with the same catalyst under the same conditions and without regeneration.

Example 4

[0085] Vapour phase dehydration of ethanol was conducted independently with catalysts B, X, Y, Z and AA (Experiments Nos. 1, 2, 6, 10, 11 and 17 from Table 3) according to the above procedure. The results of the reactions are illustrated graphically in FIG. 4.

[0086] The results show detrimental effects of the presence of alumina in a silica based support on heteropolyacid catalyst lifetime and catalyst deactivation. Catalyst B employed in Experiments 1 and 11 according to Table 3, which includes a silica support without any transition metal oxide, does not retain catalyst activity well and is almost completely deactivated after 250 hours of operation of the process. However, catalyst lifetime is not improved by modifying the silica support with alumina and initial catalyst productivity is instead severely reduced as shown with the results for Catalysts AA, Y and Z which have increasing content of alumina, employed in Experiments 6, 10 and 11 according to Table 3. The worst performing catalyst is that having a pure alumina support, corresponding to Catalyst X employed in Experiment 2.

Example 5

[0087] Vapour phase dehydration of ethanol was conducted independently with catalysts B, D and E (Experiments Nos. 1, 11, 26 and 27 from Table 3) according to the above procedure. The results of the reactions are illustrated graphically in FIG. 5.

[0088] The results show the similarity in the results for catalysts comprising different single oxide silica supports. All exhibit inferior heteropolyacid catalyst lifetime compared to mixed oxide supported heteropolyacids used in accordance with the present invention and are completely deactivated after 250 hours of operation of the process without regeneration.

Example 6

[0089] Vapour phase dehydration of ethanol was conducted independently with catalysts A and B (Experiments Nos. 28 and 29 from Table 3) according to the above procedure. The results of the reactions are illustrated graphically in FIG. 6.

[0090] The results show the similarity in the results for catalysts comprising single oxide silica supports with different loadings of silicotungstic acid (136.6 g/kg and 245.2 g/kg for Catalysts A and B respectively). Catalyst deactivation, as illustrated by a reduction in ethylene productivity (which is based on the number of moles/g of silicotungstic acid) in these reactions, is not dependent on the loading of the catalyst on the support.

Example 7

[0091] Vapour phase dehydration of ethanol was conducted independently with catalysts B and C (Experiments Nos. 30 and 31 from Table 3) according to the above procedure. The results of the reactions are illustrated graphically in FIG. 7.

[0092] The results show the similarity in the results for catalysts comprising single oxide silica supports with different loadings of silicotungstic acid (245.2 g/kg and 376.6 g/kg for Catalysts B and C respectively). Catalyst deactivation, as illustrated by a reduction in ethylene productivity (which is based on the number of moles/g of silicotungstic acid) in these reactions, is not dependent on the loading of the catalyst on the support.

[0093] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

[0094] Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0095] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope and spirit of this invention.