Process for oxidation of a lower alkene at low temperatures in ammonia-containing gas mixtures

Abstract

In a process for the oxidation of a lower alkene, such as ethylene, over a catalyst containing Cu and one or more zeolite or zeotype materials, the oxidation is conducted in the presence of ammonia in the feed gas at a process temperature below 350 C. The oxidation can be performed in a continuous process.

Claims

1. A process for the oxidation of a lower alkene over a catalyst, wherein the catalyst consists of (i) Cu or an oxide of Cu and (ii) one or more zeolite or zeotype materials, and wherein the oxidation is conducted in the presence of ammonia in the feed gas at a process temperature below 350 C. and the reaction product is ethylene oxide, ethylene glycol, acetaldehyde, or propylene oxide.

2. Process according to claim 1, wherein the catalyst consists of (i) an oxide o Cu and (ii) one or more zeolite or zeotype materials.

3. Process according to claim 1, wherein the zeotype is a silico-alumino phosphate material.

4. Process according to claim 1, in which the oxidation is performed in a continuous process.

5. Process according to claim 1, wherein the lower alkene is ethylene.

6. Process according to claim 1, wherein the reaction product is ethylene oxide.

7. A process for the oxidation of a lower alkene over a catalyst containing Cu and one or more zeolite or zeotype materials, wherein the oxidation is conducted in the presence of ammonia in the feed gas at a process temperature below 350 C. and the reaction product is ethylene glycol.

8. A process for the oxidation of a lower alkene over a catalyst containing Cu and one or more zeolite or zeotype materials, wherein the oxidation is conducted in the presence of ammonia in the feed gas at a process temperature below 350 C. and the reaction product is acetaldehyde.

9. Process according to claim 1, wherein the lower alkene is propylene.

10. Process according to claim 1, wherein the reaction product is propylene oxide.

11. Process according to claim 1, wherein the content of ammonia in the feed gas is between 1 and 5000 ppmv.

12. Process according to claim 1, wherein the content of oxygen in the feed gas is 10 vol % or lower.

13. Process according to claim 1, wherein the content of water in the feed gas is 10 vol % or lower.

14. Process according to claim 1, wherein the process temperature is 250 C. or lower.

15. Process according to claim 1, wherein one or more zeolite or zeotype materials in the catalyst have structures selected from the group consisting of AEI, AFX, CHA, KFI, ERI, GME, LTA, IMF, ITH, MEL, MFI, SZR, TUN, *BEA, BEC, FAU, FER, MOR and LEV.

16. Process according to claim 15, wherein the Cu-zeolite catalyst is selected from the group consisting of Cu-CHA, Cu-MOR, Cu-MFI, Cu-BEA, Cu-ZSM-5 and Cu-FER.

17. Process according to claim 15, wherein the Cu-based catalyst is Cu-CHA.

Description

(1) Thus, the present invention concerns a process for the oxidation of a lower alkene over a catalyst containing Cu and a zeolite or a zeotype material at a process temperature below 350 C., wherein the oxidation is conducted in the presence of ammonia in the feed gas. The presence of ammonia is essential to the oxidation of the alkene on Cu-zeolite or Cu-zeotype materials, even though it does not directly take part in the oxidation of the alkene, and it is not necessarily a part of the reaction product. It is also noted that the process of the invention implies activation of oxygen at temperatures below 350 C., and does not require the oxygen activation above 400 C. as described in Le, H. et al., ACS Catal. 7, 1403-1412 (2017) and Markovits, M. A. C. et al., Top. Catal. 59, 1554-1563 (2016).

(2) A lower alkene is a C1-C5 alkene. The preferred lower alkane is ethylene. Another preferred lower alkene is propylene.

(3) A preferred reaction product is ethylene oxide. Another preferred reaction product is propylene oxide.

(4) Other preferred reaction products are ethylene glycol and acetaldehyde.

(5) A first embodiment of the invention is a process in which a gas mixture comprising oxygen, ammonia and a lower alkene is contacted with a Cu-zeolite material at a temperature below 350 C., resulting in an alkene concentration in the product stream that is lower than the concentration in the inlet stream.

(6) Another embodiment of the invention is a process in which a gas mixture comprising oxygen, ammonia and a lower alkene is contacted with a Cu-zeotype material at a temperature below 350 C., resulting in an alkene concentration in the product stream that is lower than the concentration in the inlet stream.

(7) Another embodiment of the invention is a process in which a gas mixture comprising water, ammonia and lower alkene is contacted with a Cu-zeolite material at a temperature below 350 C., resulting in an alkene concentration in the product stream that is lower than the concentration in the inlet stream.

(8) Another embodiment of the invention is a process in which a gas mixture comprising water, ammonia and lower alkene is contacted with a Cu-zeotype material at a temperature below 350 C., resulting in an alkene concentration in the product stream that is lower than the concentration in the inlet stream.

(9) A further embodiment of the invention is a catalyst containing a mixture of a zeolite or a zeotype in the H.sup.+ or NH.sub.4.sup.+ form and an oxide of Cu.

(10) Preferably the zeolite structure of the Cu-zeolite catalyst is one or more structures selected from the group consisting of AEI, AFX, CHA, KFI, ERI, GME, LTA, IMF, ITH, MEL, MFI, SZR, TUN, *BEA, BEC, FAU, FER, MOR and LEV. It is especially preferred that the Cu-zeolite catalyst is selected from the group consisting of Cu-CHA, Cu-MOR, Cu-MFI, Cu-BEA, Cu-ZSM-5 and Cu-FER.

(11) According to the present invention, the process feed gas mixture comprises oxygen, ammonia and a lower alkene. Other gaseous compounds, such as nitrogen, water, noble gases and other hydrocarbons, can be present in the feed gas mixture as well.

(12) An advantage of the present invention is that the process can be conducted continuously without any need of re-activation of the Cu-zeolite or Cu-zeotype material.

(13) Another advantage of the present invention is that the process can be conducted isothermally at a process temperature between 150 and 350 C. A preferred embodiment of the invention is a process in which the oxidation is performed at a temperature of 250 C. or lower.

(14) A further embodiment of the invention is that the catalyst for the process comprises a mixture of a metal-free zeolite or zeotype material and an oxide of Cu.

(15) Another embodiment of the invention is a process in which a gas mixture comprising oxygen, ammonia and a lower alkene is contacted with a catalyst containing Cu and one or more zeolite or zeotype materials at a temperature below 350 C., in which the concentration of NH.sub.3 is between 1 and 5000 ppmv.

(16) Another embodiment of the invention is a process in which a gas mixture comprising oxygen, ammonia and a lower alkene is contacted with a catalyst containing Cu and one or more zeolite or zeotype materials at a temperature below 350 C., in which the concentration of oxygen is 10 vol % or lower.

(17) Another embodiment of the invention is a process in which a gas mixture comprising water, ammonia and a lower alkene is contacted with a catalyst containing Cu and one or more zeolite or zeotype materials at a temperature below 350 C., in which the concentration of water is 10 vol % or lower.