Process and reactor system for producing ammonia using ionic liquids

• US 8,808,659 B2
• Filed: 01/27/2011
• Issued: 08/19/2014
• Est. Priority Date: 01/28/2010
• Status: Active Grant

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Shiflett, Mark Brandon, Yokozeki, Akimichi
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US13/014,761
• Publication Number:
  US 20120027661A1
• Time in Patent Office: 1,300 Days
• Field of Search: 423359-363
• US Class Current: 423/359
• CPC Class Codes: C01C 1/0464 by absorption in liquids, e.g. water
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts

Abstract

A process and a reactor system for producing ammonia is described. The ammonia produced, such as by the Haber process, is absorbed into an ionic liquid. The removal of ammonia shifts the reaction equilibrium toward the production of ammonia, resulting in higher yields of ammonia.

Claims

1. A process for producing ammonia comprising the steps of:

(a) combining nitrogen and hydrogen in the presence of a catalyst to produce ammonia; and

(b) absorbing a portion of the ammonia so produced with an ionic liquid that comprises an ammonium cation.

2. The process according to claim 1 wherein the ammonium cation is represented by the structure of the following formula:

N⁺(R⁷)(R⁸)(R⁹)(R¹⁰)

wherein;

(a) R⁷, R⁸, R⁹, and R¹⁰ are independently selected from the group consisting of;

(i) —

CH₃, —

C₂H₅, or a C₃ to C₂₅ straight-chain, branched or cyclic alkane or alkene group, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH₂ and SH;

(ii) —

CH₃, —

C₂H₅, or a C₃ to C₂₅ straight-chain, branched or cyclic alkane or alkene group comprising one to three heteroatoms selected from the group consisting of O, N, Si and S, and optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH₂ and SH;

(iii) a C₆ to C₂₅ unsubstituted aryl, or a C₆ to C₂₅ unsubstituted heteroaryl, group having one to three heteroatoms independently selected from the group consisting of O, N, Si and 5, and

(iv) a C₆ to C₂₅ substituted aryl, or a C₆ to C₂₅ substituted heteroaryl, group having one to three heteroatoms independently selected from the group consisting of O, N, Si and S, and wherein the substituted aryl or substituted heteroaryl group has one to three substituents independently selected from the group consisting of;

(A) —

CH₃, —

C₂H₅, or a C₃ to C₂₅ straight-chain, branched or cyclic alkane or alkene group, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH₂ and SH,

(B) OH,

(C) NH₂, and

(D) SH; and

(v) —

(CH₂)_nSi(CH₂)_mCH₃, —

(CH₂)_nSi(CH₃)₃, and —

(CH₂)_nOSi(CH₃)_m, where n is independently 1-4 and m is independently 0-4; and

(b) optionally, at least two of R⁷, R⁸, R⁹, and R¹⁰, can together form a cyclic or bicyclic alkanyl or alkenyl group.

3. The process according to claim 1 further comprising a step of recovering the ammonia absorbed by the ionic liquid.

4. The process according to claim 1 wherein the ionic liquid comprises an anion selected from the group consisting of

(a) [BF₄]⁻

, [PF₆]⁻

, [SbF₆]⁻

, [CF₃SO₃]⁻

, [HCF₂CF₂SO₃]⁻

, [CF₃HFCCF₂SO₃]⁻

, [HCClFCF₂SO₃]⁻

, [(CF₃SO₂)₂N]⁻

, [(CF₃CF₂SO₂)₂N]⁻

, [(CF₃SO₂)₃C]⁻

, [CF₃CO₂]⁻

, [CF₃OCFHCF₂SO₃]⁻

, [CF₃CF₂OCFHCF₂SO₃]⁻

, [CF₃CFHOCF₂CF₂SO₃]⁻

, [CF₂HCF₂OCF₂CF₂SO₃]⁻

, [CF₂ICF₂OCF₂CF₂SO₃], [CF₃CF₂OCF₂CF₂SO₃]⁻

, [(CF₂HCF₂SO₂)₂N]₋

, [(CF₃CFHCF₂SO₂)₂N]⁻

, and F⁻

; and

(b) anions represented by the structure of the following formula;

5. The process according to claim 1 wherein the nitrogen and hydrogen are combined at a temperature in the range of about 300°

C. to about 550°

C.

6. The process according to claim 1 wherein the nitrogen and hydrogen are combined at a pressure in the range of about 8 MPa to about 40 MPa.

7. The process according to claim 1 wherein the ammonia is absorbed by the ionic liquid at a temperature in the range of about 20°

C. to about 200°

C.

8. The process according to claim 1 wherein the ammonia is absorbed by the ionic liquid at a pressure in the range of about 100 kPa to about 40 MPa.

9. The process according to claim 1 wherein the ionic liquid comprises a fluorinated anion.

10. The process according to claim 2 wherein an R group selected from R⁷, R⁸, R⁹ and R¹⁰ is a group substituted with F.

11. The process according to claim 1 wherein the ionic liquid comprises an anion selected from the group consisting of:

[CH₃CO₂]⁻

, [NO₃]⁻

, [SO₄]²⁻

, [HPO₃]²⁻

, [H₂PO₃]¹⁻

, [PO₄]³⁻

, [HPO₄]²⁻

, [H₂PO₄]⁻

, [HSO₃]⁻

, [CuCl₂]⁻

, Cl⁻

, Br⁻

, I⁻

, SCN⁻

, carborates optionally substituted with an alkyl or substituted alkyl group; and

carboranes optionally substituted with an alkylamine, substituted alkylamine, alkyl or substituted alkyl group.

12. The process according to claim 1 wherein the ionic liquid comprises an anion selected from the group consisting of aminoacetate, ascorbate, benzoate, catecholate, citrate, dimethylphosphate, formate, fumarate, gallate, glycolate, glyoxylate, iminodiacetate, isobutyrate, kojate, lactate, levulinate, oxalate, pivalate, propionate, pyruvate, salicylate, succinamate, succinate, tiglate, tetrafluoroborate, tetrafluoroethanesulfonate, and tropolonate.