Buffered amino alcohol solutions of N-(n-butyl)thiophosphoric triamide (NBPT) and urea fertilizers using such solutions as urease inhibitors

• US 20100206030A1
• Filed: 02/17/2009
• Published: 08/19/2010
• Est. Priority Date: 02/17/2009
• Status: Active Grant

• Current Assignee: Whitehurst Associates, Inc.
• Original Assignee: Whitehurst Associates, Inc.
• Inventors: Whitehurst, Brooks M., Whitehurst, Garnett B.
• Granted Patent: US 8,048,189 B2
• Time in Patent Office: Days
• US Class Current: 71/30
• CPC Class Codes: C05B 17/00 Other phosphatic fertilisers, e.g. soft rock phosphates, bone meal
• CPC Class Codes: C05G 3/90 for affecting the nitrification of ammonium compounds or urea in the soil
• CPC Class Codes: C07F 9/224 Phosphorus triamides
• CPC Class Codes: Y10S 71/902 Nitrification inhibition

Abstract

Reduced volatility of urea fertilizers are prepared in accordance with the present invention by first preparing an N-(n-butyl)-thiophosphoric triamide (NBPT) solution by dissolving NBPT in a mixture of an amino alcohol having the formula 1—(H)_x—N—((CH₂)_m—OH)_n where m is 1-3, x is 0 or 1, and n is 2 when x is 1 and 3 when x is 0: or the formula 2—(H)_y—N—((CH₂)—CHOH—CH₃)_z such that the length of the carbon chain where the secondary hydroxyl group is located is 3, y is 0 or 1, and z is 2 when y is 1 and 3 when y is 0, and a carboxylic acid having 6 or fewer carbon atoms. The solution is then combining with a urea fertilizer in granular or liquid form.

Claims

1. A method of preparing a solution for use in reducing the volatility of urea fertilizers comprising dissolving N-(n-butyl)-thiophosphoric triamide (NBPT) in a mixture of an amino alcohol having the formula 1—

(H)_x—

N—

((CH₂)_m—

OH)_n where m is 1-3, x is 0 or 1, and n is 2 when x is 1 and 3 when x is 0;

or the formula 2—

(H)_y—

N—

((CH₂)—

CHOH—

CH₃)_z such that the length of the carbon chain where the secondary hydroxyl group is located is 3, y is 0 or 1, and z is 2 when y is 1 and 3 when y is 0, and a carboxylic acid having 6 or fewer carbon atoms to form an NBPT solution.

2. The method of claim 1, wherein said amino alcohol is selected from the group consisting of diethanolamine, dipropanolamine, triethanolamine, tripropanolamine, diisopropanolamine, triisopropanolamine, and mixtures thereof.

3. The method of claim 1, wherein from about 15% to about 30% by weight NBPT is dissolved in said mixture.

4. The method of claim 1, wherein said NBPT is dissolved in said mixture and a co-solvent selected from the group consisting of ethylene glycol and propylene glycol.

5. The method of claim 1, wherein said amino alcohol has a pK_a of between about 7.5 and 10 and said acid has a pK_a of 5 or less.

6. A solution for use in reducing the volatility of urea fertilizers comprising N-(n-butyl)-thiophosphoric triamide (NBPT) dissolved in a mixture of an amino alcohol having the formula 1—

(H)_x—

N—

((CH₂)_m—

OH)_n where m is 1-3, x is 0 or 1, and n is 2 when x is 1 and 3 when x is 0;

or the formula 2—

(H)_y—

N—

((CH₂)—

CHOH—

CH₃)_z such that the length of the carbon chain where the secondary hydroxyl group is located is 3, y is 0 or 1, and z is 2 when y is 1 and 3 when y is 0, and a carboxylic acid having 6 or fewer carbon atoms to form an NBPT solution.

7. The solution of claim 6, wherein said amino alcohol is selected from the group consisting of diethanolamine, dipropanolamine, triethanolamine, tripropanolamine, diisopropanolamine, triisopropanolamine, and mixtures thereof.

8. The solution of claim 6, wherein from about 15% to about 30% by weight NBPT is dissolved in said mixture.

9. The solution of claim 6, further including a co-solvent.

10. The solution of claim 6, wherein said solution is diluted with water.

11. A method of producing reduced volatility of urea fertilizers comprising:

a) dissolving N-(n-butyl)-thiophosphoric triamide (NBPT) in a mixture of an amino alcohol having the formula 1—

(H)_x—

N—

((CH₂)_m—

OH)_n where m is 1-3, x is 0 or 1, and n is 2 when x is 1 and 3 when x is 0;

or the formula 2—

(H)_y—

N—

((CH₂)—

CHOH—

CH₃)_z such that the length of the carbon chain where the secondary hydroxyl group is located is 3, y is 0 or 1, and z is 2 when y is 1 and 3 when y is 0, and a carboxylic acid having 6 or fewer carbon atoms to form an NBPT solution; and

b) combining said NBPT solution with said urea fertilizer.

12. The method of claim 11, wherein said urea fertilizer is in the form of granules and said NBPT solution is coated on said granules.

13. The method of claim 11, wherein said fertilizer granules are coated with from about 0.050% to about 0.25% NBPT.

14. The method of claim 11, wherein said urea fertilizer is an aqueous urea fertilizer solution and said NBPT solution is mixed with said aqueous solution.

15. The method of claim 11, wherein said aqueous urea fertilizer solution contains with from about 0.050% to about 0.25% NBPT

16. The method of claim 11, wherein said amino alcohol is selected from the group consisting of diethanolamine, dipropanolamine, triethanolamine, tripropanolamine, diisopropanolamine, triisopropanolamine, and mixtures thereof.

17. The method of claim 11, wherein from about 15% to about 30% by weight NBPT is dissolved in said mixture of an amino alcohol and a carboxylic acid.

18. A method of producing reduced volatility of urea fertilizers comprising:

a) dissolving N-(n-butyl)-thiophosphoric triamide (NBPT) in a mixture of an amino alcohol having the formula 1—

(H)_x—

N—

((CH₂)_m—

OH)_n where m is 1-3, x is 0 or 1, and n is 2 when x is 1 and 3 when x is 0;

or the formula 2—

(H)_y—

N—

((CH₂)—

CHOH—

CH₃)_z such that the length of the carbon chain where the secondary hydroxyl group is located is 3, y is 0 or 1, and z is 2 when y is 1 and 3 when y is 0, and a carboxylic acid having 6 or fewer carbon atoms to form an NBPT solution; and

b) combining a granular urea fertilizer with said NBPT solution.

19. The method of claim 18, further including the step of coating said fertilizer granules with powdered micronutrients.

20. The method of claim 18, wherein said NBPT solution is diluted with an aqueous mixture prior to addition of micronutrients.

21. The method of claim 18, wherein said granular urea fertilizer with added micronutrients contains from about 0.050% to about 0.25% NBPT.

22. A method of producing reduced volatility liquid urea fertilizer comprising:

a) dissolving N-(n-butyl)-thiophosphoric triamide (NBPT) in a mixture of an amino alcohol having the formula 1—

H)_x—

N—

((CH₂)_m—

OH)_n where m is 1-3, x is 0 or 1, and n is 2 when x is 1 and 3 when x is 0;

or the formula 2—

(H)_y—

N—

((CH₂)—

CHOH—

CH₃)_z such that the length of the carbon chain where the secondary hydroxyl group is located is 3, y is 0 or 1, and z is 2 when y is 1 and 3 when y is 0, and a carboxylic acid having 6 or fewer carbon atoms to form an NBPT solution; and

b) mixing said NBPT solution with an aqueous solution of urea fertilizer.

23. The method of claim 22, wherein said amino alcohol is selected from the group consisting of diethanolamine, dipropanolamine, triethanolamine, tripropanolamine, diisopropanolamine, triisopropanolamine, and mixtures thereof.

24. The method of claim 22, wherein from about 15% to about 30% by weight NBPT is dissolved in said mixture.

25. The method of claim 22, wherein sufficient NBPT solution is mixed with said aqueous solution to produce an aqueous fertilizer containing from about 0.050% to about 0.25% NBPT.

26. The method of claim 22, wherein said urea fertilizer is an aqueous mixture of urea and ammonium nitrate.