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 a water-free triazine sulfide scavenging agent.

2. The composition of claim 1, wherein the water-free triazine further comprises a low volatile polar solvent.

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

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

5. 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: water-free triazine, 1,3,5-triazine derivatives of formula I, and any combination thereof, wherein formula I comprises: ##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.3o alkyl, straight or branched C.sub.1-C.sub.30 alkyl substituted with straight or branched C.sub.1-C.sub.30alkoxy.

6. The method of claim 5, 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.30alkoxy.

7. The method of claim 5, wherein the scavenger is of formula I, and each of R.sup.1, R.sup.2, and R.sup.3 is the same.

8. The method of claim 5, 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.

9. The method of claim 5, wherein R.sup.1 is CH.sub.2CH.sup.2OH, R.sup.2 is CH.sub.2CH.sub.2OH, and R.sup.3 is CH.sub.2CH.sub.2OH.

10. The method of claim 5, wherein the scavenger is water-free triazine.

11. The method of claim 5, wherein the water-free triazine further comprises a low volatile polar solvent.

12. The composition of claim 1, further comprising hexamethylenetetramine.

13. The method of claim 5, further comprising combining the polyphosphoric acid treated asphalt or the asphalt mix with hexamethylenetetramine.

14. 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: water-free triazine, a 1,3,5-triazine derivative of formula I, and any combination thereof, wherein formula I comprises: ##STR00008## wherein 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.30alkyl substituted with straight or branched C.sub.1-C.sub.30alkoxy.

15. The composition of claim 14, 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.30alkoxy.

16. The composition of claim 14, 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.

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

18. The composition of claim 14, 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.

19. The composition of claim 14, wherein R.sup.1 is CH.sup.2CH.sub.2OH, R.sup.2 is CH.sub.2CH.sub.2OH, and R.sup.3 is CH.sub.2CH.sub.2OH.

20. The composition of claim 14, wherein the polyphosphoric acid is present in the asphalt or asphalt mix at about 1 wt. %.

Description

DETAILED DESCRIPTION

(1) The present disclosure is related to a family of sulfide scavengers for use in PPA-treated asphalt, and the preparation thereof. The scavengers are particularly efficient at reducing hydrogen sulfide emissions of PPA-treated asphalt. The present disclosure is directed to a composition comprising PPA-treated asphalt with one or more sulfide scavengers. The present disclosure is also directed to a method of reducing hydrogen sulfide emission from PPA-treated asphalt, and the preparation thereof

(2) Unless expressly stated to the contrary, use of the term a is intended to include at least one or one or more. For example, a scavenger is intended to include at least one scavenger or one or more scavengers.

(3) Any ranges given either in absolute terms or in approximate terms are intended to encompass both, and any definitions used herein are intended to be clarifying and not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges (including all fractional and whole values) subsumed therein.

(4) The terms comprise(s), include(s), having, has, can, contain(s), and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The singular forms a, and and the include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments comprising, consisting of and consisting essentially of, the embodiments or elements presented herein, whether explicitly set forth or not. In accordance with the present disclosure, the phrases consist essentially of, consists essentially of, consisting essentially of, and the like limit the scope of a claim to the specified materials or steps and those materials or steps that do not materially affect the basic and novel characteristic(s) of the claimed invention.

(5) The term alkyl as used herein, refers to a hydrocarbon radical with a defined number of carbon atoms (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 carbons). Branched alkyl groups include, but are not limited to, sec-butyl, tert-butyl, isobutyl, isopentyl, neopentyl, 1-methylbutyl, 2-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1,1-dimethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4-dimethylpentyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3,4-dimethylpentyl, 4,4-dimethylpentyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, 1,2,2-trimethylbutyl, 1,2,3-trimethylbutyl, 1,3,3-trimethylbutyl, 2,2,3-trimethylbutyl, 2,3,3-trimethylbutyl, 1,1,2,2-tetramethylpropyl, 1-ethylpentyl, 2-ethylpentyl, 3-ethylpentyl, 1-ethyl-1-methylbutyl, 1-ethyl-2-methylbutyl, 1-ethyl-3-methylbutyl, 2-ethyl-l-methylbutyl, 2-ethyl-2-methylbutyl, 2-ethyl-3-methylbutyl, 1-propylbutyl, 1,1-diethylpropyl, etc.

(6) In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 30. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 20. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 15. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 10. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 8.

(7) The term alkoxyl as used herein, refers to a ether radical with a defined number of carbon atoms (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 carbons). Branched alkyl groups include, but are not limited to, secbutoxy, tert-butoxy, isobutoxy, isopentoxy, neopentoxy, 1-methylbutoxy, 2-methoxybutoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 1-ethylpropoxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, 3,3-dimethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethylbutoxy, 2-ethylbutoxy, 1-methylhexoxy, 2-methylhexoxy, 3-methylhexoxy, 4-methylhexoxy, 5-methylhexoxy, 1,1-dimethylpentoxy, 1,2-dimethylpentoxy, 1,3-dimethylpentoxy, 1,4-dimethylpentoxy, 2,2-dimethylpentoxy, 2,3-dimethylpentoxy, 2,4-dimethylpentoxy, 3,3-dimethylpentoxy, 3,4-dimethylpentoxy, 4,4-dimethylpentoxy, 1,1,2-trimethylbutoxy, 1,1,3-trimethylbutoxy, 1,2,2-trimethylbutoxy, 1,2,3-trimethylbutoxy, 1,3,3-trimethylbutoxy, 2,2,3-trimethylbutoxy, 2,3,3-trimethylbutoxy, 1,1,2,2-tetramethylpropoxy, 1-ethylpentoxy, 2-ethylpentoxy, 3-ethylpentoxy, 1-ethyl-l-methylbutoxy, 1-ethyl-2-methylbutoxy, 1-ethyl-3-methylbutoxy, 2-ethyl-1-methylbutoxy, 2-ethyl-2-methylbutoxy, 2-ethyl-3-methylbutoxy, 1-propylbutoxy, 1,1-diethylpropoxy, etc.

(8) In some embodiments, the number of carbon atoms for the alkyl portion of the alkoxy group is between 6 and 30. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 20. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 15. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 10. In some embodiments, the number of carbon atoms for the alkyl group is between 6 and 8.

(9) As used herein, the term asphalt refers to any of a variety of materials that are solid or semisolid at room temperature and which gradually liquefy when heated, and in which the predominant constituents are naturally occurring bitumens (or kerogens) or which are bitumen like materials obtained as residue in petroleum refining. It is expressly contemplated that asphalt as used herein includes what ASTM defines as asphalt: a dark brown to black cementitious material in which the predominant constituents are bitumens that occur in nature or are obtained in petroleum processing. Asphalts characteristically contain very high molecular weight hydrocarbons called asphaltenes. These are essentially soluble in carbon disulfide, and aromatic and chlorinated hydrocarbons. Bitumen is a generic term defined by the ASTM as a class of black or dark-colored cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches and asphaltenes are typical. The ASTM further classifies asphalts or bituminous materials as solids, semi-solids, or liquids using a penetration test for consistency or viscosity. In this classification, solid materials are those having a penetration of not more than 1 millimeter when a load of 100 grams is applied for 5 seconds while at 25 C., and semi-solids are those having a penetration of more than 1 millimeter when a load of 50 grams is applied for 5 seconds while at 25 C. Semi-solid and liquid asphalts predominate in commercial practice today. For example, any asphalt bottoms fraction, as well as naturally occurring asphalts, tars and pitches and may be used interchangeably herein with the term bitumen. The term asphaltic concrete means asphalt used as a binder with appropriate aggregate added, typically for use as a paving material.

(10) The term bottoms fraction refers to a crude fraction having a flash point of about 70 F. or greater.

(11) The term water-free as used herein, refers to compositions where the amount of water present is less than about 5 weight percent.

(12) Compositions

(13) The compositions disclosed herein include asphalt or an asphalt mix that has been treated with polyphosphoric acid. The composition also includes a sulfide scavenging agent. The sulfide scavenging agent is selected from hexamethylenetetramine, water-free triazine, and 1,3,5-triazine derivatives of formula I

(14) ##STR00003##
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.

(15) In some embodiments, the sulfide scavenging agent is hexamethylenetetramine, sometimes abbreviated (HMTA) which has the structure:

(16) ##STR00004##

(17) In some embodiments, the sulfide scavenging agent is water-free triazine. Triazine has the structure:

(18) ##STR00005##

(19) In some embodiments, the sulfide scavenging agent is a 1,3,5-triazine derivatives of formula I

(20) ##STR00006##
having the substituents for R.sup.1, R.sup.2, and R.sup.3 defined above. In some embodiments, 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. In some embodiments, each of 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.

(21) In some embodiments, each of R.sup.1, R.sup.2, and R.sup.3 is independently hydroxyl substituted straight or branched C.sub.1-C.sub.30 alkyl. In some embodiments, each of R.sup.1, R.sup.2, and R.sup.3 is independently hydroxyl substituted straight or branched C.sub.6-C.sub.30 alkyl.

(22) In some embodiments, each of R.sup.1, R.sup.2, and R.sup.3 is independently straight or branched C.sub.1-C.sub.30 alkyl substituted with straight or branched C.sub.1-C.sub.30 alkoxy. In some embodiments, each of R.sup.1, R.sup.2, and R.sup.3 is independently straight or branched C.sub.6-C.sub.30 alkyl substituted with straight or branched C.sub.1-C.sub.30 alkoxy. In some embodiments, each of R.sup.1, R.sup.2, and R.sup.3 is independently straight or branched C.sub.6-C.sub.30 alkyl substituted with straight or branched C.sub.6-C.sub.30 alkoxy.

(23) In some embodiments, each of R.sup.1, R.sup.2, and R.sup.3 is the same. In some embodiments, R.sup.1 is different from R.sup.2 and R.sup.3. In some embodiments, R.sup.1 and R.sup.2 are the same. In some embodiments, R.sup.1 and R.sup.2 are the same and are also different from R.sup.3. In some embodiments, R.sup.1 is different from R.sup.2 and R.sup.3, and R.sup.2 is different from R.sup.3.

(24) The asphalt composition includes polyphosphroric acid. Such acid modification of the asphalt generally results in asphalt compositions that exhibit improved low temperature performance, for example. The asphalt composition includes less than or equal to about 5 wt. % acid. In some emobidments, the asphalt composition includes less than or equal to about 3 wt. % acid. In some embodiments, the asphalt composition includes less than about 2.5 wt. % acid. In some embodiments, the asphalt composition includes less than about 1 wt. % acid and may include from about 0.01 wt. % to about 1 wt. % acid, or from about 0.05 wt. % to about 1 wt. % acid or from about 0.1 wt. % to about 1 wt. % acid, for example.

(25) The compositions disclosed herein can optionally include one or more additives. Suitable additives include, but are not limited to, asphaltene inhibitors, paraffin inhibitors, corrosion inhibitors, scale inhibitors, emulsifiers, water clarifiers, dispersants, emulsion breakers, gas hydrate inhibitors, biocides, pH modifiers, surfactants, solvents, and combinations thereof

(26) The asphalt composition may further include additives, such as sulfonating agents, crosslinking agents or combinations thereof, for example. The asphalt composition may include from about 0.001 wt. % to about 5 wt. % of total additives or from about 0.01 wt. % to about 3 wt. % of total additives, for example.

(27) The crosslinking agents may be activators (e.g., zinc oxide), accelerators, such as sulfur compounds (e.g., mercaptobenzothizole (MBT)) or both accelerators and activators, such as a zinc salt of MBT, for example. In one embodiment, the crosslinking agent is a metal oxide.

(28) The additives may further include unsaturated functional monomers, unsaturated carboxylic acids, unsaturated dicarboxylic acids, unsaturated anhydrides, unsaturated esters, unsaturated amides or combinations thereof, for example.

(29) Preparation Methods

(30) Generally, the compositions are made with water-free sulfide scavengers and to facilitate handling of polyphosphoric acid treated asphalt and asphalt mixtures at a temperature of greater than about 250 C. or less. In some embodiments, the temperature of the asphalt or asphalt mixture is less than about 200 C. In some embodiments, the temperature of the asphalt or asphalt mixture is less than about 150 C. In some embodiments, the temperature of the asphalt or asphalt mixture is less than about 100 C. In some embodiments, the temperature of the asphalt or asphalt mixture is less than about 90 C.

(31) Illustrative methods of forming such asphalt compositions are described below, but in no way limit the methods that may be utilized to form such compositions. For example, in one embodiment, asphalt is heated in a first mixing vessel to a temperature of from about 140 C. to 205 C. The asphalt concentrate may then be transferred to a second mixing vessel or remain in the first mixing vessel.

(32) Polyphosphoric acid is added. The acid is added in a timed release sufficient to avoid foaming, such as from about 20 minutes to about 1 hour, for example. The acid, however, can be added at any point in the process and to any vessel or conduit in the process. For example, the acid can be added to a first or second mixing vessel or to a conduit operably connecting the first and second mixing vessels.

(33) Sulfide scavenger is added. The scavenger can be added before the polyphosphoric acid is added or thereafter. The addition of the sulfur scavenger under agitation typically for 15 minutes to 10 hours. The concentration of the sulfur scavenger varies according to the workability of the mixture, and typically could range from 5% wt to 90% and most typically from 20 to 60% wt. The rate of addition into the asphalt or bitumen is proportionel to its solid content and varies from 0.01 to 10%, preferably from 0.1 to 0.5% wt. Other process control steps include thorough agitation and mixing to assure mixture of the scavenger with the asphalt mixture.

(34) Product Applications

(35) The asphalt compositions described herein can be used for many applications, such as road paving, sealing, water proofing, asphalt cement and/or roofing, for example.

(36) The compounds, compositions, methods, and processes will be better understood by reference to the following examples, which are intended as an illustration of and not a limitation upon the scope of the present disclosure.

EXAMPLES

(37) 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.

(38) 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.

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

(40) TABLE-US-00001 TABLE 1 Observed H.sub.2S scavenging on 1 wt % PPA treated asphalt at 148 C. using HMTA. H2S Residual Initial H2S/ Rxn Dosage/ Final Scavenger Time/hrs ppm Ratio g H2S/ppm HMTA 48 13000 Blank / / 48 13000 0.1 0.65 65 48 13000 0.2 1.3 5 48 13000 0.5 3.25 15 48 13000 1 6.5 0

(41) TABLE-US-00002 TABLE 2 Observed scavenging of H.sub.2S on 1 wt % PPA treated asphalt at 148 C. using water-free triazine. H2S Residual Initial H2S/ Rxn Dosage/ Final Scavenger Time/hrs ppm Ratio ppm H2S/ppm Water Free 24 7500 Blank / / Triazine 24 7500 0.25 1875 400 24 7500 0.5 3750 60 24 7500 1 7500 20