Recycling of styrene butadiene rubber and like materials

Patent metadata

Field	Value
Publication number	US-9458303-B1
Application number	US-201414560614-A
Country	US
Kind code	B1
Filing date	Dec 4, 2014
Priority date	Dec 4, 2013
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

Present embodiments provide efficient and cost-effective use of chloramines such as monochloramine, NH 2 Cl, to degrade styrene butadiene rubber, a material from which tires and other products are made, so that it can be recycled, and do so by overcoming the limitations of monochloramine due to its thermodynamic instability by achieving and maintaining adequate monochloramine concentrations for the degrading process.

First claim

What is claimed is:

1. A process for degrading styrene butadiene rubber in a reactor, comprising:
contacting particles of styrene butadiene rubber with at least one chloramine compound in solution under stirring, the at least one chloramine compound being chosen from the group monochloramine, dichloramine, and nitrogen trichloride; and
continuously providing fresh chloramine to the reactor.

2. The process of claim 1 , wherein the step of providing fresh chloramine to the reactor comprises forming a solution of chloramine compound in a makeup supply vessel and adding the formed solution to the reactor.

3. The process of claim 1 , wherein the temperature within the reactor is between about 45° C. and 92° C.

4. The process of claim 1 , wherein the step of providing flesh chloramine to the reactor comprises adding hypochlorite and ammonia species in aqueous solution to the reactor.

5. The process of claim 2 , further comprising regulating the flow of the chloramine compound between the chloramine makeup supply vessel and the reactor.

6. The process of claim 1 , further comprising determining the concentration of chloramine in the reactor; comparing the concentration of chloramine in the reactor to a threshold value; and, if the concentration is below the threshold, adding fresh chloramine to the reactor.

7. The process of claim 1 , wherein the at least one chloramine compound includes monochloramine, and further comprising favoring the formation of monochloramine over dichloramine and nitrogen trichloride when providing fresh chloramine to the reactor.

8. The process of claim 7 , further comprising reducing the particle size of styrene butadiene rubber.

9. The process of claim 7 , wherein the particle size of a substantial majority of styrene butadiene rubber particles is between about 0.5-1 millimeter.

10. The process of claim 9 , wherein the particle size of a substantial majority of styrene butadiene rubber particles is no greater than about 0.5 millimeter.

11. The process of claim 7 , wherein the step of favoring the formation of monochloramine over dichloramine and nitrogen trichloride comprises maintaining a pH in a range of about 8-9.

12. The process of claim 11 , at a pH of about 8.3.

13. The process of claim 11 , wherein the step of maintaining a pH in a range of about 8-9 comprises adding to the reactor a solution of a basic salt of an alkali metal.

14. The process of claim 1 , further comprising determining a decomposition rate of at least one chloramine compound and determining a feed rate for providing fresh chloramine to the reactor proportional to the decomposition rate.

15. The process of claim 14 , wherein the step of determining a decomposition rate of at least one chloramine compound comprises determining a concentration of the at least one chloramine compound as a function of reaction temperature.

16. The process of claim 1 , wherein the at least one chloramine compound is dissolved in an aqueous solution.

17. A reactor for degrading styrene butadiene rubber, comprising:
a reaction vessel for accommodating at least one chloramine compound;
a chloramine makeup supply vessel communicating with the reaction vessel;
a feedline configured to deliver a solution of a basic salt of an alkali metal to the reaction vessel;
a flow regulator configured to control the flow chloramine compound from the chloramine makeup supply vessel to the reaction vessel; and
an outlet for removing degraded chloramine compound solution from the reactor.

18. The reactor of claim 17 , wherein the at least one chloramine compound is chosen from the group monochloramine, dichloramine, and nitrogen trichloride, and further comprising a pH meter for determining the pH of a solution.

19. The reactor of claim 18 , further comprising a stirring implement.

20. The process of claim 1 , further comprising subjecting the degraded styrene butadiene rubber to a revulcanizing process, thereby crosslinking adjacent polymer molecules of styrene butadiene rubber.

Assignees

• Univ Louisville Res Found Inc

Inventors

• Willing Gerold A
• Kroeger Patrick

Classifications

• C08J11/28 Primary

  by treatment with organic compounds containing nitrogen, sulfur or phosphorus · CPC title

• B01J2208/00893

  Feeding means for the reactants · CPC title

• C08J11/16 Primary

  by treatment with inorganic material (C08J11/14 takes precedence) · CPC title

• C08J2309/06

  Copolymers with styrene · CPC title

• B01J8/082

  Controlling processes · CPC title