PROCESS FOR INITIATING A HIGHLY SELECTIVE ETHYLENE OXIDE CATALYST

• US 20090082584A1
• Filed: 09/26/2007
• Published: 03/26/2009
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: SD Lizenzverwertungsgesellschaft mbH & Co. KG
• Original Assignee: SD Lizenzverwertungsgesellschaft mbH & Co. KG
• Inventors: Castagnola, Norma B., Rizkalla, Nabil, Billig, Barry Jay
• Granted Patent: US 7,553,980 B2
• Time in Patent Office: Days
• US Class Current: 549/534
• CPC Class Codes: C07D 301/10 with catalysts containing silver or gold
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts

Abstract

A process for initiating a highly selective ethylene oxide catalyst is provided in which the highly selective ethylene oxide catalyst is operated first as a ‘standard’ Ag-based catalyst (e.g., a catalyst that contains only silver and alkali metal, especially cesium). Moreover, the inventive initiation procedure is more efficient when the concentration of carbon dioxide in the feed is higher than 6 vol. %, and even more efficient when the concentration of carbon dioxide in the feed is higher than 10 vol. %, of the feed mixture during the initiation period.

Claims

1-3. -3. (canceled)

5. (canceled)

12. (canceled)

15. A method for epoxidation of ethylene comprising:

contacting a catalyst bed including a silver-based highly selective epoxidation catalyst with a feed gas composition at a first temperature during an initiation period, said feed gas composition including ethylene, oxygen, a moderator and carbon dioxide, said carbon dioxide is present in said feed gas composition in a first concentration of greater than about 6 vol. %;

increasing the first temperature to a second temperature to produce a desired concentration of ethylene oxide;

adjusting the feed gas composition in order to maintain said desired concentration of ethylene oxide while achieving a desired catalyst work rate; and

lowering the second temperature to a third temperature, while simultaneously lowering the carbon dioxide concentration to a second concentration of about 5 vol. % or less.

4. The method of claim 17 wherein said support is essentially alpha-alumina having a surface area from 0.1 to 10 m²/g.

6. The method of claim 18 wherein the Group IIA metal-containing compound comprises beryllium, magnesium, calcium, strontium, barium or combinations thereof.

7. The process of claim 18 wherein the transition metal-containing compound comprises an element selected from Groups IVA, VA, VIA, VIIA and VIIIA of the Periodic Table of the Elements, or combinations thereof.

8. The method of claim 7 wherein the transition metal-containing compound comprises molybdenum, tungsten, chromium, titanium, hafhium, zirconium, vanadium, thorium, tantalum, niobium or combinations thereof.

9. The method of claim 8 wherein the transition metal-containing compound comprises molybdenum or tungsten or combinations thereof.

10. The method of claim 17 wherein the alkali metal-containing compound comprises lithium, sodium, potassium, rubidium, cesium or combinations thereof.

11. The method of claim 17 wherein the alkali metal-containing compound comprises cesium and lithium.

13. The method of claim 15 wherein said first temperature is from about 180°

C. to about 220°

C. and said second temperature is from about 230°

C. to about 270°

C.

14. The method of claim 15 wherein said adjusting the feed composition includes changing the concentration of carbon dioxide or ethylene.

16. The method of claim 15 wherein said first concentration of carbon dioxide in said feed gas is greater than about 10 vol. %.

17. The method of claim 15 wherein said silver-based highly selective epoxidation catalyst comprises a support, a catalytically effective amount of silver or a silver-containing compound, a promoting amount of rhenium or a rhenium-containing compound, and a promoting amount of one or more alkali metals or alkali-metal-containing compounds.

18. The method of claim 17 wherein said catalyst further comprises a promoting amount of one or more Group IIA metal-containing compounds, one or more transition metal-containing compounds, one or more sulfur-containing compounds, one or more fluorine-containing compounds, one or more phosphorus-containing compounds, one or more boron-containing compounds, or combinations thereof.

20. The method of claim 15 wherein the carbon dioxide concentration is lowered to a second concentration of about 2 vol. % or less.

19. (canceled)

21. A method for epoxidation of ethylene comprising:

contacting a catalyst bed including a silver-based highly selective epoxidation catalyst with a feed gas composition at a first temperature, said feed gas composition including ethylene, oxygen, a moderator and carbon dioxide, said carbon dioxide is present in said feed gas composition in a first concentration of greater than about 10 vol. %;

increasing the first temperature to a second temperature to produce a desired concentration of ethylene oxide;

adjusting the feed gas composition in order to maintain said desired concentration of ethylene oxide while achieving a desired catalyst work rate; and

lowering the second temperature to a third temperature, while simultaneously lowering the carbon dioxide concentration to a second concentration of about 5 vol. % or less.