HYDROGEN SULFIDE SCAVENGERS FOR POLYMER TREATED ASPHALT

Abstract

Scavenging compounds and compositions useful in reducing sulfide emissions from polymer treated asphalt, such as polyphosphoric acid, are disclosed. The scavengers include hexamethyl-enetetramine, water-free triazine, and water-free 1,3,5-triazine derivatives of formula I. Methods of using the compositions to reduce hydrogen sulfide emissions from asphalt are also disclosed.

Claims

1. A composition, comprising: (a) asphalt or an asphalt mix further comprising polyphosphoric acid; and (b) a sulfide scavenging agent selected from the group consisting of: hexamethylenetetramine, water-free triazine, and 1,3,5-triazine derivatives of formula I ##STR00007## where each of R.sup.1, R.sup.2, and R.sup.3 is independently selected from straight or branched C.sub.1-C.sub.30 alkyl, hydroxyl substituted straight or branched C.sub.1-C.sub.30 alkyl, straight or branched C.sub.1-C.sub.30 alkyl substituted with straight or branched C.sub.1-C.sub.30 alkoxy.

2. The composition of claim 1, wherein the scavenger is of formula I, and each of R.sup.1, R.sup.2, and R.sup.3 is independently selected from straight or branched C.sub.6-C.sub.30 alkyl, hydroxyl substituted straight or branched C.sub.6-C.sub.30 alkyl, straight or branched C.sub.6-C.sub.30 alkoxy substituted with straight or branched C.sub.1-C.sub.30 alkoxy.

3. The composition of claim 1, wherein the scavenger is of formula I, and each of R.sup.1, R.sup.2, and R.sup.3 is selected from C.sub.1-C.sub.9 straight or branched alkyl.

4. The composition of claim 1, wherein the scavenger is of formula I, and each of R.sup.1, R.sup.2, and R.sup.3 is the same.

5. The composition of claim 1, wherein the scavenger is of formula I, and at least one of R.sup.1, R.sup.2, and R.sup.3 is different from the other R.sup.1, R.sup.2, and R.sup.3.

6. The composition of claim 1, wherein R.sup.1 is CH.sub.2CH.sub.2OH, R.sup.2 is CH.sub.2CH.sub.2OH, and R.sup.3 is CH.sub.2CH.sub.2OH.

7. The composition of claim 1, wherein the scavenger is hexamethylenetetramine.

8. The composition of claim 1, wherein the scavenger is water-free triazine.

9. The composition of claim 8, wherein the water-free triazine further comprises a low volatile polar solvent.

10. The composition of claim 9, wherein the low volatile polar solve is selected from diethylene glycol, 2-butoxyethanol, propylene glycol, monoethanol amine, and mixtures of the same.

11. The composition of claim 1, wherein the polyphosphoric acid is present in the asphalt or asphalt mix at about 1 wt. %.

12. A method of reducing hydrogen sulfide emission from asphalt, comprising: combining polyphosphoric acid treated asphalt or asphalt mix with a sulfide scavenging agent, the sulfide scavenging agent selected from the group consisting of: hexamethylenetetramine, water-free triazine, and 1,3,5-triazine derivatives of formula I ##STR00008## where each of R.sup.1, R.sup.2, and R.sup.3 is independently selected from straight or branched C.sub.1-C.sub.30 alkyl, hydroxyl substituted straight or branched C.sub.1-C.sub.30 alkyl, straight or branched C.sub.1-C.sub.30 alkyl substituted with straight or branched C.sub.1-C.sub.30 alkoxy.

13. The method of claim 12, wherein the scavenger is of formula I, and each of R.sup.1, R.sup.2, and R.sup.3 is independently selected from straight or branched C.sub.6-C.sub.30 alkyl, hydroxyl substituted straight or branched C.sub.6-C.sub.30 alkyl, straight or branched C.sub.6-C.sub.30 alkoxy substituted with straight or branched C.sub.1-C.sub.30 alkoxy.

14. The method of claim 12, wherein the scavenger is of formula I, and each of R.sup.1, R.sup.2, and R.sup.3 is the same.

15. The method of claim 12, wherein the scavenger is of formula I, and at least one of R.sup.1, R.sup.2, and R.sup.3 is different from the other R.sup.1, R.sup.2, and R.sup.3.

16. The method of claim 12, wherein R.sup.1 is CH.sub.2CH.sub.2OH, R.sup.2 is CH.sub.2CH.sub.2OH, and R.sup.3 is CH.sub.2CH.sub.2OH.

17. The method of claim 12, wherein the scavenger is hexamethylenetetramine.

18. The method of claim 12, wherein the scavenger is water-free triazine.

19. The method of claim 18, wherein the water-free triazine further comprises a low volatile polar solvent.

Description

EXAMPLES

[0049] Sulfide emissions from polyphosphoric acid treated asphalt were measured to examine the effectiveness of various sulfide scavengers. All H.sub.2S levels reported below and observed were measured by modified ASTM D5705 at annotated temperature and residual time.

[0050] The H.sub.2S testing was conducted by adding 1 wt % PPA to asphalt and keeping the mixture at 300 F. for 24 hours to allow any H.sub.2S release. At the end of this 24 hour period, the vapor phase H.sub.2S concentration of sample was determined and recorded as initial H.sub.2S. The scavenger was then added to this PPA treated asphalt sample, and the sample was kept at 300 F. for another 24 or 48 hours. The vapor phase H.sub.2S after this 24 or 48 hour period was measured and reported as final H.sub.2S.

[0051] Tested hydrogen sulfide scavengers included hexamethylenetetramine (HMTA)Table 1 and water-free triazineTable 2.