OIL SOLUBLE SULFIDE SCAVENGERS WITH LOW SALT CORROSION AND METHODS OF MAKING AND USING THESE SCAVENGERS

Abstract

Sulfide scavengers useful to reduce sulfide concentration in fluid streams and methods of using these scavengers. The scavengers comprise oil soluble reaction products of formaldehyde/N-substituted hydroxylamines and can be used to reduce, for example, H.sub.2S content in viscous hydrocarbon oil streams.

Claims

1. A method for reducing sulfides in a fluid comprising contacting said fluid with a reaction product of a N-substituted hydroxylamine and formaldehyde (AHAF).

2. A method as recited in claim 1 wherein said N-substituted hydroxylamine comprises one or more members selected from the group consisting of N,N-dimethylhydroxylamine, N,N-diethylhydroxylamine, N,N-dibenzylhydroxylamine, N-ethylhydroxylamine, N-propylhydroxylamine, N-isopropylhydroxylamine, N-butylhydroxylamine, N-phenylhydroxylamine, N-cyclohexylhydroxylamine, N-tert-butylhydroxylamine, N-benzylhydroxylamine.

3. A method as recited in claim 1 wherein said reaction product (AHAF) has the formula: ##STR00004## wherein n is from about 0-10 and R.sub.1 and R.sub.2 are each independently chosen from H, C.sub.1-C.sub.10 linear, branched, and cyclic alkyl, alkenyl, or aryl groups; with the proviso that both R.sub.1 and R.sub.2 are not H.

4. The method as recited in claim 1 wherein said sulfides comprise one or more members selected from the group consisting of organic sulfides, mercaptans, thiols, COS, and H.sub.2S.

5. The method of claim 1 wherein said fluid is (i) a hydrocarbon, (ii) natural gas, (iii) water, or (iv) a multiphase mixture of hydrocarbon.

6-8. (canceled)

9. The method of claim 5 wherein said hydrocarbon is a hydrocarbon oil selected from the group consisting of crude oil, naptha, gas oil, bunker fuel, marine diesel, asphalt, and bitumen.

10. The method of claim 1 wherein from about 1 to 100,000 ppm by volume of said reaction product is brought into contact with said fluid based upon one million parts of said fluid.

11. (canceled)

12. The method as recited in claim 3 wherein R.sub.1 and R.sub.2 are both C.sub.1-C.sub.10 alkyl.

13. The method as recited in claim 12 wherein both R.sub.1 and R.sub.2 are ethyl.

14. A method for making a dialkylhydroxylamine/formaldehyde reaction product comprising reacting a hydroxylamine of the formula RRNOH with formaldehyde, wherein R and R are each independently chosen from H, linear, branched, and cyclic C.sub.1-C.sub.10 alkyl, alkenyl, or aryl groups; with the proviso that both R.sub.1 and R.sub.2 are not H; said method being conducted at a temperature of about above 60 C. for about 0.5-2.0 hours.

15. A method as recited in claim 14 wherein said reaction is conducted in the presence of an organic solvent.

16. A method as recited in claim 14 wherein said reaction is conducted at a temperature of about 80-90 C.

17. A method as recited in claim 14 wherein R and R are both C.sub.1-C.sub.10 alkyl.

18. A method as recited in claim 17 wherein R and R are both ethyl.

19. A method as recited in claim 14 wherein the molar ratio of formaldehyde:N-substituted hydroxylamine is from about 0.5-5 moles formaldehyde to about 1 mole of N-substituted hydroxylamine.

20. (canceled)

21. A method as recited in claim 19 wherein said formaldehyde is paraformaldehyde.

22. An N-substituted hydroxylamine/formaldehyde reaction product having the structure ##STR00005## wherein n is an integer from 0-10; R.sub.1 and R.sub.2 are each independently chosen from H, C.sub.1-C.sub.10 linear, branched, alkyl, alkenyl, or aryl groups with the proviso that both R.sub.1 and R.sub.2 are not H.

23. The reaction product as recited in claim 22, wherein said reaction product is oil soluble.

24. The reaction product as recited in claim 23 wherein both R.sub.1 and R.sub.2 are C.sub.1-C.sub.10 alkyl.

25. The reaction product as recited in claim 24 wherein both R.sub.1 and R.sub.2 are ethyl.

Description

DETAILED DESCRIPTION

[0013] One aspect of the invention pertains to methods of making a N-substituted hydroxylamine/formaldehyde reaction product (AHAF) wherein a N-substituted hydroxylamine of the formula RRNOH is reacted with formaldehyde (e.g., paraformaldehyde) neat or in the presence of an organic solvent. The reaction may proceed at temperatures of from above about 60 C. for about 0.5-2.0 hours. In certain embodiments, the reaction may be carried out for about 1 hour at temperatures of about 80-90 C. In the above N-substituted hydroxyl amine formula, R and R are independently selected from H, linear, branched, and cyclic C.sub.1-C.sub.10 alkyl, alkenyl, or aryl groups; with the proviso that both R and R are not H. Examples of R and R include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and decyl. Particularly noteworthy is diethylhydroxylamine (DEHA).

[0014] In some embodiments, the hydroxyamine is chosen from the group consisting of N,N-dimethylhydroxylamine, N,N-diethylhydroxylamine, N,N-dibenzylhydroxylamine, N-ethylhydroxylamine, N-propylhydroxylamine, N-isopropylhydroxylamine, N-butylhydroxylamine, N-phenylhydroxylamine, N-cyclohexylhydroxylamine, N-tert-butylhydroxylamine, N-benzylhydroxylamine.

[0015] In those embodiments in which an organic solvent is employed, heavy aromatic naptha solvent may be mentioned as exemplary. The adduct reaction product may remain in the solvent and it can be used as such to reduce sulfide content of hydrocarbon fluid streams, or the adduct can be separated from the reaction medium via conventional separation techniques and then used as a sulfide scavenger. Other organic solvents that may be mentioned include pentane, hexane, cyclohexane, benzene, toluene, chloroform, diethyl ether, dichloromethane, tetrahydrofuran (THF), ethyl acetate, etc. The molar ratio of the reactants, formaldehyde:N-substituted hydroxylamine, may range from about 0.5-5:1 and a ratio of about 1-3:1 can also be mentioned as exemplary.

[0016] The AHAF reaction products have the structure

##STR00003##

wherein n is an integer from about 0-10; R.sub.1 and R.sub.2 are each independently selected from H, C.sub.1-C.sub.10 linear, branched, and cyclic alkyl, alkenyl, or aryl groups; with the proviso that both R.sub.1 and R.sub.2 are not H. In the case wherein DEHA is reacted with formaldehyde (e.g. paraformaldehyde), R.sub.1 and R.sub.2 are both ethyl.

[0017] In other aspects of the invention, a method for reducing sulfides from fluid streams is disclosed wherein the AHAF reaction products are brought into contact with such fluid streams that contain one or more organic sulfides, mercaptans, thiols, COS, and H.sub.2S. The fluid streams may include liquid and gas media, and these streams may be hydrocarbon streams or aqueous streams. The reaction products may be employed in amounts of from about 1 to 100, 000 ppm by volume of the fluid stream. Other exemplary dosage ranges that may be mentioned include 500-3,000 ppm, especially about 1,000 ppm.

[0018] The AHAF reaction products possess advantage in that they present low risk for amine salt corrosion of metallurgies in contact with the fluid streams and have a higher flash point compared to amines such as dipropylamine and dibutylamine; thus abating safety and handling concerns. The adducts have a low PPI (salt precipitation index) thus reducing salt corrosion risk. The adducts are oil soluble and can therefore be used in heavy, viscous hydrocarbon streams.

[0019] In other exemplary embodiments, the fluid stream treated can comprise a fluid hydrocarbon stream or an aqueous fluid stream. These fluid streams may, for example, comprise gas/liquid mixtures from oilfield processes, pipelines, tanks, tankers, refineries, and chemical plants. Additionally, the fluid stream may comprise farm discharge city water, etc. Other additional fluid streams include water, waste water, and process water containing H.sub.2S.

[0020] The invention will be further described in connection with the following illustrated examples that should not be construed as limiting the invention.

EXAMPLES

Example 1

[0021] Formaldehyde: DEHA adduct (2:1 mole ratio), neat. 45 gm of solid paraformaldehyde was placed in the flask. Anhydrous DEHA (65 gm) was added. The mixture was stirred and heated to 90 C. for 1 hour, until paraformaldehyde complete dissolved. Cooled to room temperature, collected 110 gm of adduct (100%).

Example 2

[0022] Formaldehyde: DEHA adduct (2:1 mole ratio), in solvent. 65 gm of solid paraformaldehyde was placed in the flask. Anhydrous DEHA (89 gm) and 51 gm of Aromatic A-150 solvent were added. Mixture was stirred and heated to 90 C. for 1 hour, until paraformaldehyde completely dissolved. Aromatic A-150 is a heavy aromatic solvent naptha. Cooled to room temperature, collected 205 gm of adduct (100%).

Example 3

[0023] Formaldehyde: DEHA adduct (1:1 mole ratio), neat. 23 gm of solid paraformaldehyde was placed in the flask. Anhydrous DEHA (65 gm) was added. Mixture was stirred and heated to 90 C. for 1 hour, until paraformaldehyde completely dissolved. Cooled to room temperature, collected 88 gm of adduct (100%).

Example 4

[0024] Formaldehyde: DEHA adduct (1:1 mole ratio), in solvent. Amount of 33 gm of solid paraformaldehyde was placed in the flask. Anhydrous DEHA 89 gm) and 51 gm of Aromatic A-150 solvent was added. Mixture was stirred and heated to 90 C. for 1 hour, until paraformaldehyde completely dissolved. Cooled to room temperature, collected 173 gm of adduct (100%).

Example 5

[0025] In order to demonstrate the efficacy of the N-substituted hydroxylamine-formaldehyde adducts in reducing H.sub.2S in hydrocarbon media, 150 ml of bunker fuel in 500 ml was mixed with or without sulfide scavenger candidate chemical and heated to 75 C. The headspace H.sub.2S vapor concentration was measured using a stain/dragger tube after 2 hours. The following table shows the resulting data.

TABLE-US-00001 TABLE ppm H.sub.2S @ Salt Precipitation Chemical Additive Dose 75 C. Potential Index of Amine Blank 0 900 NA 40% Glyoxal 1000 500 NA DMAPA triazine 1000 20 High Dialkylamine-HCHO adduct 1000 30 Low HCHO:DEHA adduct (1:1) 1000 0 Very Low (Example 3 above) DMAPA = dimethylaminopropyl amine

[0026] While illustrative embodiments of the invention have been described, it should be understood that the present invention is not so limited, and modifications may be made without departing from the present invention. The scope of the invention is defined by the appended claims viewed under either a literal infringement or doctrine of equivalents analysis.