Method of ammonia production

• US 4,863,707 A
• Filed: 01/06/1989
• Issued: 09/05/1989
• Est. Priority Date: 09/30/1982
• Status: Expired due to Fees

• Current Assignee: Engelhard Corporation (BASF SE)
• Original Assignee: Engelhard Corporation (BASF SE)
• Inventors: Yarrington, Robert M., McShea, William T. III
• Primary Examiner(s): Doll, John
• Assistant Examiner(s): Langel, Wayne A.
• Application Number:
  US07/296,385
• Time in Patent Office: 242 Days
• Field of Search: 423/359, 252/373, 252/376, 502/527
• US Class Current: 423/359
• CPC Class Codes: C01B 2203/0827 at least part of the fuel being a recycle stream
• CPC Class Codes: C01B 2203/142 At least two reforming, decomposition or partial oxidation steps in series
• CPC Class Codes: C01B 2203/146 At least two purification steps in series
• CPC Class Codes: C01B 2203/147 Three or more purification steps in series
• CPC Class Codes: C01B 2203/148 involving a recycle stream to the feed of the process for making hydrogen or synthesis gas
• CPC Class Codes: C01B 2203/82 Several process steps of C01B2203/02 - C01B2203/08 integrated into a single apparatus
• CPC Class Codes: C01B 3/382 Multi-step processes

Abstract

A process for the production of ammonia from a hydrocarbonaceous feed, comprising preheating an inlet stream comprising a hydrocarbonaceous feed, H₂ O, air and oxygen to a preheat temperature sufficiently high to initiate catalytic oxidation of the feed, introducing the preheated inlet stream into a first catalyst zone comprising a monolithic body having a plurality of gas flow passages extending therethrough and having a catalytically effective amount of palladium and platinum catalytic components dispersed therein, passing the first zone effluent to a second catalyst zone containing a platinum group metal steam reforming catalyst to form a hydrogen-containing synthesis gas, and passing the synthesis gas into an ammonia synthesis loop.

Claims

1. A process for the production of ammonia from a hydrocarbonaceous feed, comprising the steps of:

(a) introducing an inlet stream comprising a hydrocarbonaceous feed, H₂ O, air and oxygen at a temperature sufficiently high to initiate catalytic oxidation of the feed into a first catalyst zone comprising a monolithic body having a plurality of gas flow passages extending therethrough and having a catalytically effective amount of palladium and platinum catalytic components dispersed therein, the amounts of feed, H₂ O, and oxygen introduced into said first catalyst zone being controlled to maintain in said inlet stream an H₂ O to C ratio from about 0.5 to 5 and O₂ to C ratio of from about 0.35 to 0.65;

(b) contacting the inlet stream within said first catalyst zone with said palladium and platinum catalytic components to initiate and sustain therein catalytic oxidation of said feed to produce hydrogen and carbon oxides therefrom, the temperature of at least a portion of said monolithic body being at least about 250°

F. (139°

C.) greater than the ignition temperature of said inlet stream, and oxidizing in said first catalyst zone a quantity, less than all, of said feed, which quantity is sufficient to head such first zone effluent to an elevated temperature high enough to catalytically steam reform, within a second catalyst zone defined below, hydrocarbon remaining in such first zone effluent without supplying external heat thereto;

(c) passing the first zone effluent, while still at an elevated temperature, from said first catalyst zone to a second catalyst zone containing a catalyst monolith having a platinum group metal steam reforming catalyst dispersed thereupon and contacting the first zone effluent in said second catalyst zone with said reforming catalyst to react hydrocarbons therein with H₂ O to produce hydrogen and carbon oxide therefrom;

(d) withdrawing the effluent of said second catalyst zone as a hydrogen-containing synthesis gas, and removing heat therefrom to cool said synthesis gas;

(e) reacting carbon monoxide in said synthesis gas with H₂ O to produce hydrogen;

(f) passing said synthesis gas into an ammonia synthesis loop to react the hydrogen with nitrogen thereof over an ammonia synthesis catalyst at ammonia synthesis conditions; and

(g) withdrawing ammonia as product from said ammonia synthesis loop.

2. The process of claim 1 wherein the proportion of air to oxygen in said inlet stream is such as to provide oxygen enrichment of the air in said inlet stream to at least about 33 volume percent oxygen.

3. The process of claim 1 or claim 2 wherein said hydrocarbonaceous feed is a hydrocarbon feed.

4. The process of claim 3 wherein the preheat temperature is from about 800°

F. to 1400°

F. (427°

C. to 760°

C.).

5. The process of claim 4 wherein said first catalyst zone is maintained at a temperature of from about 1750°

F. to 2400°

F. (954°

C. to 1316°

C.) and the first zone effluent is introduced into said second catalyst zone at substantially the same temperature.

6. The process of claim 4 wherein a volumetric hourly rate of at least 100,000 volumes of throughput per volume of catalyst is maintained in said first catalyst zone.

7. The process of claim 6 wherein a volumetric hourly rate of from about 2,000 to 20,000 volumes of throughput per volume of catalyst is maintained in said second catalyst zone.

8. The process of claim 4 wherein said first catalyst zone comprises palladium, platinum, and, optionally, rhodium catalytic components distended upon a refractory metal oxide support layer carried on said monolithic body.

9. The process of claim 8 wherein said catalytic component of said first catalyst zone comprises, on an elemental metal basis, about 10 to 90% by weight palladium and about 90 to 10% by weight platinum.

10. The process of claim 9 wherein said catalytic component of said first catalyst zone comprises about 25 to 75% by weight palladium, and about 75 to 25% by weight platinum.

11. The process of claim 10 wherein said catalytic component of said first catalyst zone comprises from about 60 to about 40% by weight platinum and from about 40% to about 60% by weight palladium.

12. The process of claim 8 wherein said steam reforming catalyst comprises one or both of platinum and rhodium catalytic components.

13. The process of claim 8 wherein said steam reforming catalyst comprises, an elemental metal basis from about 10 to 90% rhodium and from about 90 to 10% by weight platinum.

14. The process of claim 13 wherein said steam reforming catalyst comprises from about 20 to 40% by weight rhodium and 80 to 60% by weight platinum.

15. The process of claim 2 wherein said feed is a hydrocarbon and including the additional step of treating the synthesis gas withdrawn from said second catalyst zone to convert carbon monoxide therein to carbon dioxide and then removing carbon dioxide from the synthesis gas to provide a carbon oxides-depleted ammonia synthesis gas.

16. The process of claim 15 wherein the step of converting carbon monoxide to carbon dioxide comprises adding oxygen to the synthesis gas withdrawn from said second catalyst zone and contacting the resulting mixture with a catalyst effective for the selective oxidation of carbon monoxide to carbon dioxide in the presence of hydrogen.

17. The process of claim 16 wherein the oxygen added to said synthesis gas is added as air, and the amount of added air is calculated to bring the nitrogen content of the synthesis gas to from about 2.9 to 3.1:

1 molar ratio of hydrogen to nitrogen.

18. The process of claim 3 wherein the amounts of feed, H₂ O, air and oxygen introduced into said first catalyst zone are controlled to maintain in said inlet stream an H₂ O to C ratio of from about 1 to 4, and an O₂ to C ratio of from about 0.5 to 0.6.

19. The process of claim 3 wherein the amounts of feed, H₂ O, air and oxygen introduced into said first catalyst zone are controlled to provide oxygen enrichment of the air in said inlet stream to about 33 to 50 volume percent oxygen.

20. The process of claim 3 carried out at a pressure of from about 100 to 1500 psia.

21. The process of claim 1, wherein the process comprises the additional step of removing sulfur containing compounds and H₂ O from the synthesis gas after the carbon monoxide is reacted in said synthesis gas with H₂ O to produce hydrogen.

22. The process of claim 1, comprising the additional step of removing carbon dioxide from said effluent of said second catalyst zone.

23. The process for the production of ammonia from a hydrocarbon feed, comprising the steps of:

(a) introducing an inlet stream comprising a hydrocarbon feed, H₂ O, air and oxygen at a temperature of about 800°

F. to 1400°

F. (427°

C. to 760°

C.) and introducing the inlet stream at a pressure of from about 100 to 1500 psia into a first catalyst zone comprising a monolithic body having a plurality of gas flow passages extending therethrough and having a catalytically effective amount of palladium and platinum catalytic components dispersed therein, the amounts of hydrocarbonaceous feed, H₂ O and oxygen introduced into said first catalyst zone being controlled to maintain in said inlet stream an H₂ O to C ratio of from about 0.5 to 5, and an O₂ to C ratio of from about 0.4 to 0.65;

(b) contacting the inlet stream within said first catalyst zone with said palladium and platinum catalytic components at a volumetric hourly rate of at least about 100,000 volumes of throughput per volume of catalyst per hour to initiate and sustain therein catalytic oxidation of said hydrocarbonaceous feed to produce hydrogen and carbon oxides therefrom and oxidizing in said first catalyst zone a quantity, less than all, of said hydrocarbonaceous feed, which quantity is sufficient to heat such first zone effluent to an elevated temperature of from about 1750°

F. to 2400°

F. (954°

C. to 1316°

C.);

the temperature of at least a portion of the monolithic catalyst being maintained at least about 250°

F. (139°

C.) above the ignition temperature of the inlet stream;

(c) passing the first zone effluent, while still at said elevated temperature, from said first catalyst zone to a second catalyst zone containing a catalyst monolith having a platinum group metal steam reforming catalyst dispersed thereupon and contacting the first zone effluent in said second catalyst zone with said steam reforming catalyst at an hourly volumetric rate of from about 2,000 to 20,000 volumes of throughput per volume of catalyst to react hydrocarbons therein with H₂ O to produce hydrogen and carbon oxides therefrom; and

(d) withdrawing the effluent of said second catalyst zone as a hydrogen-containing synthesis gas; and

removing heat therefrom to cool said synthesis gas;

(e) withdrawing the effluent of said second catalyst zone as a hydrogen-containing synthesis gas, and removing heat therefrom to cool said synthesis gas;

(f) reacting carbon monoxide in said synthesis gas with H₂ O to produce hydrogen;

(g) passing said synthetic gas into an ammonia synthesis loop to react the hydrogen with nitrogen thereof over an ammonia synthesis catalyst at ammonia synthesis conditions.

24. The process of claim 23 wherein the proportion of air to oxygen is such as to provide oxygen enrichment of the air in said inlet stream from about 33 to 50 volume percent oxygen, whereby to provide a nitrogen-containing hydrogen-rich synthesis gas .

25. The process of claim 24 further including converting carbon monoxide in the effluent of said second catalyst zone to carbon dioxide and then removing carbon dioxide from said effluent of said second catalyst zone.

26. The process of claim 25 wherein the effluent withdrawn from said second catalyst zone is further treated to remove sulfur and sulfur compounds therefrom.

27. The process of claim 23 or claim 24 wherein said platinum group metal catalyst of said first catalyst zone comprises palladium, platinum, and, optionally, rhodium catalytic components and said steam reforming catalyst comprises platinum and rhodium catalytic components.

28. The process of claim 27 wherein said catalytic components of said first catalyst zone comprise, on an elemental metal basis, about 10 to 90% by weight palladium, 90 to 10% by weight platinum and said catalytic components of said second catalyst zone comprise, on an elemental basis, about 10 to 90% by weight rhodium and 90 to 10% by weight platinum.

29. The process of claim 28 wherein said catalytic components of said first catalyst zone comprise about 25 to 75% by weight palladium, 75 to 25% by weight platinum and said catalytic components of said second catalyst comprise comprise about 20 to 40% by weight rhodium, and 80 to 60% by weight platinum.

30. The process of claim 23, wherein the process comprises the additional step of removing sulfur containing compounds and H₂ O from the synthesis gas after the carbon monoxide is reacted in said synthesis gas with H₂ O to produce hydrogen.

31. The process of claim 23, comprising the additional step of removing carbon dioxide from said effluent of said second catalyst zone.