Synergized Acetals Composition And Method For Scavenging Sulfides And Mercaptans

Abstract

This invention provides a composition comprising I. at least one reaction product between a nitrogen-free monohydric alcohol and an aldehyde or ketone, and II. at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde or ketone, and optionally III. at least one reaction product from III.a) formaldehyde, and III.b) an amine, selected from the group consisting of primary alkyl amines having 1 to 4 carbon atoms, and primary hydroxy alkyl amines having 2 to 4 carbon atoms, and optionally IV. at least one solid suppression agent selected from the group consisting of IV(a). alkali or alkaline earth metal hydroxides IV(b). mono-, di- or tri-hydroxy alkyl, aryl or alkylaryl amines, IV(c). mono-, di- or tri-alkyl, aryl or alkylaryl primary, secondary and tertiary amines or IV(d). multifunctional amines and IV(e). mixtures of compounds of groups IV(a) to IV(c). wherein alkyl is C.sub.1 to C.sub.15, aryl is C.sub.6 to C.sub.15 and alkylaryl is C.sub.7 to C.sub.15.

Claims

1. A composition comprising I. at least one reaction product between a nitrogen-free monohydric alcohol and an aldehyde or ketone, and II. at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde or ketone, wherein the reaction products I. and II. are selected from the group consisting of hemiacetals and acetals, and the aldehyde or ketone contains 1 to 10 carbon atoms, and the monohydric alcohol comprises 1 to 15 carbon atoms, and the polyhydric alcohol contains 2 to 20 carbon atoms and 2 to 6 hydroxy groups.

2. The composition according to claim 1, further comprising III. at least one reaction product from formaldehyde and a compound selected from the group consisting of ammonia and an amine, the amine being selected from the group consisting of primary alkyl amines having 1 to 4 carbon atoms, and primary hydroxy alkyl amines having 2 to 4 carbon atoms.

3. The composition according to claim 1, further comprising IV. at least one inorganic or organic alkaline compound that functions as a solids suppression agent.

4. The composition according to claim 1, wherein the aldehyde or ketone contains 1 to 4 carbon atoms.

5. The composition according to claim 1, wherein the aldehyde or ketone is selected from the group consisting of formaldehyde, paraformaldehyde, glyoxal, acetaldehyde, propionaldehyde, butyraldehyde and glutaraldehyde.

6. The composition according to claim 1, wherein the aldehyde or ketone is formaldehyde.

7. The composition according to claim 1, wherein the monohydric alcohol comprises 1 to 5 carbon atoms.

8. The composition according to claim 1, wherein the monohydric alcohol is an aliphatic alcohol.

9. The composition according to claim 1, wherein the monohydric alcohol is selected from the group consisting of methanol, ethanol, propanol, iso-propanol, n-butanol, iso-butanol, tert-butanol, pentanol, hexanol, heptanol and octanol, and any mixture thereof.

10. The composition according to claim 1, wherein the polyhydric alcohol is selected from the group consisting of monoethyleneglycol, diethylene glycol, triethylene glycol propylene glycol, butylene glycol, neopentyl glycol, pentaerythritol, glycerol and oligomers of glycerol.

11. The composition according to claim 1, wherein the reaction product between a polyhydric alcohol and an aldehyde or ketone is selected from the group consisting of the compounds of formulae (2) to (5) ##STR00011## wherein p is a number from 2 to 10, and R.sub.1 is H or C.sub.1 to C.sub.8 alkyl, and R.sub.2 is CH.sub.2OH, and ##STR00012## wherein R.sub.3 and R.sub.4 independently are H or CH.sub.2OH ##STR00013## wherein m is 1 to 10, and ##STR00014## wherein R.sub.5 is H, CH.sub.3, (CH.sub.2).sub.zCH.sub.3 z is 1 to 10 x is 1 to 5.

12. The composition according to claim 1, wherein the reaction product III of an amine and formaldehyde corresponds to the formula (1b) ##STR00015## wherein each R.sup.1 is C.sub.1 to C.sub.4 alkyl or C.sub.2 to C.sub.4 hydroxy alkyl.

13. The composition according to claim 1, wherein the reaction product III of an amine and formaldehyde corresponds to formula (1a) ##STR00016## wherein R is H or methyl, and n is 1 or 2.

14. The composition according to claim 13, wherein the compound of formula 1 is 3,3′-methylenebis-5-methyl-oxazolidine.

15. The composition according to claim 1, wherein the reaction product Ill of an amine and formaldehyde is present in the composition in an amount from 1 wt.-% to 20 wt. %.

16. The composition according to claim 1, further comprising an alkyl dimethyl benzyl ammonium chloride according to formula (8) as a corrosion inhibitor ##STR00017## wherein R.sup.9 is C.sub.8 to C.sub.18 alkyl.

17. The composition according to claim 16, wherein the compound of formula (8) is present in an amount between 0.01 and 5 wt.-%.

18. The composition according to claim 1, further comprising a demulsifier in an amount between 0.1 to 10 wt. %.

19. The composition according to claim 18, wherein the demulsifier is selected from the group consisting of polysorbates, fatty alcohols, polymers comprising ethylene oxide, polymers comprising propylene oxide, ethylene oxide-propylene oxide copolymers, alkyl polyglucosides, alkylphenol ethoxylates, alkyl polyethylene oxide, alkylbenzenesulfonic acid and ethoxylated and/or propoxylated alkyl phenol-formaldehyde resins.

20. The composition according to claim 18, wherein the demulsifier corresponds to the formula (6) ##STR00018## wherein R.sub.10 is C.sub.2 to C.sub.4 alkylene, R.sub.11 is C.sub.1 to C.sub.18 alkyl, k is a number from 1 to 200, m is a number from 1 to 100.

21. The composition according to claim 18, wherein the demulsifier is dodecylbenezesulfonic acid ##STR00019##

22. The composition according to claim 18, wherein the demulsifier is a mixture of at least one compound of formula (6) and at least one compound of formula (7) in a weight ratio of from 5:1 to 1:5.

23. The composition according to claim 3, wherein the alkaline compound IV. is selected from the group consisting of IV(a) alkaline metal salts or alkaline earth metal salts IV(b) ammonia; alkyl, aryl or alkylaryl amines IV(c) hydroxy alkyl, hydroxyl aryl or hydroxy alkylaryl amines IV(d) multifunctional amines containing besides an amino group, at least one further functional group selected from the group consisting of amino groups, ether groups and acid groups or an ester, amide or salt thereof and IV(e) mixtures of compounds of groups IV(a) to IV(c) wherein “alkyl” means C.sub.1 to C.sub.20 alkyl, “aryl” means C.sub.6 to C.sub.20 aryl and “alkylaryl” means C.sub.7 to C.sub.20 alkylaryl.

24. The composition according to claim 1, comprising 1 to 50 wt. % of the reaction product between a monohydric alcohol and an aldehyde or ketone.

25. The composition according to claim 1, comprising 1 to 95 wt. % of the reaction product between a polyhydric alcohol and an aldehyde or ketone.

26. The composition according to claim 1, comprising 0.1 to 10 wt. % of at least one solids suppression agent.

27. The composition according to claim 1, comprising water ad 100 wt.-%.

28.-33. (canceled)

Description

EXAMPLES

Preparation of Hemiacetals

[0135] In a stirred reactor alcohols were charged with the quantity given in table 1 together with 0.25 wt.-% of sodium hydroxide solution at 50 wt.-%. This mixture was homogenized for 10 minutes before paraformaldehyde (93 wt.-%) was added in the amounts given in table 1 over a period of approximately 30 minutes. The reaction mixture was warmed while stirring for 2 hours at a temperature between 80 to 85° C. After the reaction time, the mixture was cooled to 30° C.

[0136] In the reaction products the molar amounts of hemiacetal in respect to the total amount of hydroxyl groups charged and the content of free formaldehyde (CH.sub.2O) were determined by .sup.1H NMR spectroscopy.

TABLE-US-00001 TABLE 1 Preparation of hemiacetals and acetals Reactor charge reaction product (Hemi-) monohydric alcohol; polyhydric alcohol; paraformaldehyde (hemi-) CH.sub.2O acetal charge [g] charge [g] [g] acetal [wt.-%] A1 methanol 500 — 500 98% 0.07 A2 ethanol 600 — 420 99% 0.06 A3 i-propanol 600 — 320 99% 0.08 A4 2-EH 800 — 200 98% 0.11 A5 — ethyleneglycol 500 520 97% 0.12 A6 — diethylenglycol 600 360 96% 0.16 A7 — glycerol 600 410 66% 0.05 A8 — pentaerythritol 500 480 98% 0.12 A9 — pentaerythritol 600 430 75% 0.04 A10 ethanol 100 ethyleneglycol 490 430 75% 0.02 A11 ethanol 80 ethyleneglycol 400 470 99% 0.03 A12 methanol 70 glycerol 550 450 70% 0.02 A13 methanol 80 glycerol 570 370 55% 0.02 A14 ethanol 120 Glycerol 450 440 80% 0.02 A15 ethanol 160 pentaerythritol 350 440 98% 0.03 2-EH = 2-ethyl hexanol

[0137] Further materials used were [0138] hexahydro-1,3,5-trimethyl-s-triazin (HTT) and 3,3′-methylenebis-5-methyloxazolidine (MBO) as the synergists according to group III. [0139] NaOH (5 wt.-% aqueous solution), triethylamine (TEA), monoethanolamine (MEA) and piperazine (PIP) were used as the solids suppressants according to group IV. All these materials were commercial grades.

Scavenger Performance Tests—Efficiency

[0140] In order to demonstrate the improved efficiency of the instant invention in removing sulfhydryl compounds compared to group I respectively group II compounds alone, the removal of H.sub.2S from an oil and from an oil/water mixture was measured.

[0141] The oil used was a mixture of kerosene with 10% of xylene with zero bottom sediment and water (BS&W) to simulate oil field conditions.

[0142] The oil/water mixture was a mixture of the oil described above and brine (in a 50:50 volume ratio of oil to aqueous phase) to mimic the efficiency in hydrated crude oil.

[0143] In a 500 mL stirred autoclave (Parr reactor), 350 mL of the oil respectively the oil/brine mixture was de-aerated for 1 hour with N.sub.2, then saturated with a sour gas mixture of 0.2 wt.-% H.sub.2S and 99.8 wt.-% CO.sub.2, by purging this gas into the oil resp. oil/brine mixture with a flow rate of 0.6 L/min. After equilibration by the sour gas mixture, 1.000 ppm of the composition to be tested was injected into the autoclave by an HPLC pump. If mixtures of (hemi-)acetals were used, their proportions by weight are given in tables 2 and 3; the amounts of synergist and solids suppressant refer to their portion in the composition and are therefore included in said dosage rate.

[0144] The performance tests were carried out at 30° C. and under 1 bar, using a gas chromatograph to measure the outlet H.sub.2S content in the gas phase every two minutes. Then, a graph of the measured values of H.sub.2S content (ppm) versus time (min) was plotted. The amount of hydrogen sulfide scavenged is the area above the resultant performance curve, which is calculated by the integration of the curve. For all samples the integration of the curve was done up to 60 min after the injection of H.sub.2S-scavenger. As the output parameter of this performance test L.sub.sc/kgH.sub.2S (Liters of H.sub.2S scavenger required to remove 1 kg of H.sub.2S from the system) has been determined for 6 minutes and 1 hour of analysis. All consumption values are averages of three repeat tests. The test results have been summarized in Table 2 and Table 3. Percentages mean weight percent if not indicated otherwise.

TABLE-US-00002 TABLE 2 Performance tests for H.sub.2S-scavengers in oil (zero BS&W) L.sub.sc/kg H.sub.2S Synergist solids @ 6 @ 1 Example (Hemi)acetal (2 wt.-%) suppressant min. hour P1 (comp.) A2 — — 20.76 9.56 P2 (comp.) A3 — — 21.23 10.04 P3 (comp.) A4 — — 32.60 16.20 P4 (comp.) A5 — — 18.65 9.01 P5 (comp.) A6 — — 18.09 8.47 P6 (comp.) A1 + A2 (1:1) — — 19.12 9.85 P7 (comp.) A5 + A6 (2:1) — — 17.24 8.86 P8 A2 + A5 (1:4) — — 14.10 7.02 P9 A2 + A5 (1:1) — — 14.48 7.35 P10 A4 + A5 (1:3) — — 13.86 7.13 P11 A10 — — 12.95 6.89 P12 A11 — — 13.22 6.70 P13 A3 + A6 — — 14.27 7.54 P14(comp.) A2 MBO — 5.65 4.63 P15(comp.) A3 MBO — 5.86 4.86 P16 (comp.) A4 MBO — 9.98 8.05 P17 (comp.) A5 MBO — 5.10 4.21 P18 (comp.) A6 MBO — 5.28 4.36 P19 A2 + A5 (1:4) MBO 3.10 2.72 P20 A2 + A5 (1:1) MBO — 3.21 2.86 P21 A4 + A5 (1:3) MBO — 3.25 2.80 P22 A10 MBO — 2.98 2.61 P23 A11 MBO — 2.92 2.55 P24 A3 + A6 (1:3) MBO — 3.11 2.75 P25 (comp.) A2 MBO 5% MEA 4.76 4.06 P26 (comp.) A3 MBO 8% PIP 4.80 4.12 P27 (comp.) A4 MBO 10% TEA 8.12 6.95 P28 (comp.) A5 MBO 5% MEA 4.29 3.68 P29 (comp.) A6 MBO 8% PIP 4.23 3.57 P30 A2 + A5 (1:4) MBO 5% MEA 2.27 1.97 P31 A2 + A5 (1:1) MBO 5% MEA 2.35 2.04 P32 A4 + A5 (1:3) MBO 10% TEA 2.64 2.25 P33 A10 MBO 5% MEA 2.12 1.89 P34 A11 MBO 5% MEA 2.26 2.00 P35 A3 + A6 (1:3) MBO 8% PIP 2.49 2.21

TABLE-US-00003 TABLE 3 Performance tests for H.sub.2S-scavenging in a mixture of the oil and brine (50:50 volume ratio of oil to aqueous phase) L.sub.sc/kg H.sub.2S solids @ 6 @ 1 Example (Hemi)acetal Synergist suppressant min. hour P36 (comp.) A1 — — 23.36 10.04 P37 (comp.) A2 — — 23.82 10.20 P38 (comp.) A5 — — 23.11 9.50 P39 (comp.) A7 — — 20.80 8.91 P40 (comp.) A8 — — 19.64 8.52 P41 (comp.) A9 — — 19.22 8.20 P42 A2 + A5 (1:4) — — 15.22 6.69 P43 A10 — — 15.47 6.77 P44 A1 + A7 (1:3) — — 14.96 6.61 P45 A1 + A7 (1:1) — — 15.82 6.96 P46 A12 — — 14.92 6.48 P47 A13 — — 15.44 6.88 P48 A2 + A8 (1:1) — — 15.71 6.90 P49 A2 + A8 (1:5) — — 14.88 6.56 P50 A2 + A9 (1:1) — — 16.05 7.01 P51 A14 — — 14.66 6.50 P52 (comp.) A1 HTT — 8.76 7.04 P53 (comp.) A2 MBO — 8.40 6.88 P54 (comp.) A5 MBO — 8.56 6.80 P55 (comp.) A7 HTT — 9.30 7.56 P56 (comp.) A8 HTT — 8.07 6.52 P57 (comp.) A9 HTT — 8.41 6.92 P58 A2 + A5 (1:4) MBO — 6.28 5.44 P59 A10 MBO — 6.15 5.26 P60 A1 + A7 (1:3) HTT — 6.25 5.30 P61 A1 + A7 (1:1) HTT — 6.38 5.45 P62 A12 HTT — 5.84 5.12 P63 A13 HTT — 6.50 5.78 P64 A2 + A8 (1:1) HTT — 5.95 5.17 P65 A2 + A8 (1:5) HTT — 5.85 5.03 P66 A2 + A9 (1:1) HTT — 5.92 5.28 P67 A14 HTT — 6.14 5.19 P68 (comp.) A1 HTT 5% NaOH 6.91 5.72 P69 (comp.) A2 MBO 10% MEA 6.52 5.56 P70 (comp.) A5 MBO 10% MEA 7.05 5.92 P71 (comp.) A7 HTT 5% NaOH 7.33 6.24 P72 (comp.) A8 HTT 10% MEA 6.31 5.25 P73 (comp.) A9 HTT 10% MEA 6.73 5.57 P74 A2 + A5 (1:4) MBO 10% MEA 4.42 3.86 P75 A10 MBO 10% MEA 3.96 3.54 P76 A1 + A7 (1:3) HTT 5% NaOH 4.26 3.68 P77 A1 + A7 (1:1) HTT 5% NaOH 4.49 3.89 P78 A12 HTT 5% NaOH 3.93 3.47 P79 A13 HTT 5% NaOH 4.07 3.62 P80 A2 + A8 (1:1) HTT 10% MEA 4.18 3.65 P81 A2 + A8 (1:5) HTT 10% MEA 3.72 3.35 P82 A2 + A9 (1:1) HTT 10% MEA 4.10 3.67 P83 A15 HTT 10% MEA 3.86 3.38 P84 A2 + A5 (1:4) — 10% MEA 7.86 4.42 P85 A10 — 10% MEA 7.73 4.28 P86 A14 HTT — 6.23 5.35 P87 A14 — 10% TEA 7.82 4.38

[0145] In the tests including a synergist the portion of MBO was 2 wt.-%, the portion of HTT was 6 wt.-% of the scavenger formulation

[0146] In tables 2 and 3 the lower consumption of the scavenger to remove 1 kg of H.sub.2S, the more efficient is the scavenger. In the inventive examples the mixtures of acetals being based on mixtures of monohydric alcohols and polyhydric alcohols are more efficient than the single components. The efficiency is further improved by the incorporation of a synergist and/or a solids suppressant. Furthermore, incorporation of the synergist enhances the reaction rate in the initial phase of the test as can be seen from the difference between scavenging efficiency after 6 minutes versus 1 hour.

Scavenger Performance Tests—Gas Breakthrough

[0147] The performance of the H.sub.2S scavengers according to the invention is evaluated for their ability to remove H.sub.2S from a flowing gas stream by passing gas laden with H.sub.2S through a column of fluid containing the scavenger chemical. A sour gas mixture of 0.2% H.sub.2S and 99.8% CO.sub.2 is purged with a flow rate of 60 mL/min through 440 mL of a 22% active solution of the scavenger composition in water. Under these conditions the average contact time of gas and scavenger is about 4 seconds. Initially all of the H.sub.2S is removed from the gas stream and no H.sub.2S is detected in the effluent gas. At some point in time (the breakthrough time or TBT) the chemical can no longer entirely remove H.sub.2S from the gas stream and H.sub.2S is observed in the effluent. This parameter is a measure of the efficacy of the scavenger especially for contact tower applications with short contact time. The longer the break through time the more efficient is the chemical scavenger.

[0148] The effect of the solids suppression agent is rated by visual inspection of the spent scavenger fluid after the gas breakthrough test. The degree of solids formation is rated opaque>turbid>opalescent>clear.

[0149] The overall concentration of the scavenger formulations in all examples is 22 wt.-%, i. e. in examples where synergist and/or solids suppressant is present the concentration of (hemi-)acetals is reduced accordingly.

TABLE-US-00004 TABLE 4 Gas breakthrough times for different (hemi-)acetals solids suppres- TBT visual example (hemi-)acetal synergist sant [min] inspection B1 (comp.) A1 — — 31 opaque B2 (comp.) A2 — — 29 opaque B3 (comp.) A3 — — 27 opaque B4 (comp.) A5 — — 17 opaque B5 (comp.) A7 — — 35 opaque B6 (comp.) A1 + A2 (1:1) — — 31 opaque B7 (comp.) A5 + A7 (1:1) — — 37 opaque B8 A2 + A5 (1:1) — — 45 opaque B9 A2 + A5 (1:4) — — 47 opaque B10 A10 — — 52 opaque B11 A11 — — 58 opaque B12 A12 — — 55 opaque B13 A1 + A7 (1:4) — — 58 opaque B14 A3 + A7 (1:2) — — 49 opaque B15 A1 7% MBO — 76 turbid B16 A2 3% HTT — 69 turbid B17 A3 5% HTT — 74 turbid B18 A5 3% HTT — 78 turbid B19 A7 7% MBO — 77 turbid B20 A2 + A5 (1:1) 3% HTT — 82 turbid B21 A2 + A5 (1:4) 3% HTT — 89 turbid B22 A10 3% HTT — 87 turbid B23 A11 3% HTT — 84 turbid B24 A12 7% MBO — 81 turbid B25 A1 + A7 (1:4) 5% MBO 85 turbid B26 A3 + A7 (1:2) 5% HTT — 80 turbid B27 A1 — 10% MEA 149 opalescent B28 A2 — 15% PIP 146 opalescent B29 A3 — 15% PIP 134 opalescent B30 A5 — 15% PIP 157 opalescent B31 A7 — 10% MEA 150 opalescent B32 A2 + A5 (1:1) — 15% PIP 164 opalescent B33 A2 + A5 (1:4) — 15% PIP 182 opalescent B34 A10 — 15% PIP 169 opalescent B35 A11 — 15% PIP 178 opalescent B36 A12 — 10% MEA 171 opalescent B37 A1 + A7 (1:4) — 15% PIP 172 opalescent B38 A3 + A7 (1:2) — 15% PIP 163 opalescent B39 A1 7% MBO 10% MEA 215 clear B40 A2 3% HTT 15% PIP 200 clear B41 A3 5% HTT 15% PIP 192 clear B42 A5 3% HTT 15% PIP 226 clear B43 A7 7% MBO 10% MEA 222 clear B44 A2 + A5 (1:1) 3% HTT 15% PIP 298 clear B45 A2 + A5 (1:4) 3% HTT 15% PIP 321 clear B46 A10 3% HTT 15% PIP 334 clear B47 A11 3% HTT 15% PIP 348 clear B48 A12 7% MBO 10% MEA 342 clear B49 A1 + A7 (1:4) 5% MBO 15% PIP 346 clear B50 A3 + A7 (1:2) 5% HTT 15% PIP 316 clear

[0150] A comparison of the inventive examples and the comparative examples shows that mixtures of (hemi-)acetals containing reaction products of monohydric and polyhydric alcohols have a higher TBT than the single components or mixtures of components of the same group. The addition of a synergist according to group III increases the H.sub.2S scavenging activity of (hemi-)acetals and especially of mixtures of (hemi-)acetals significantly. The scavenging process becomes faster and more efficient. The addition of a solids suppressant further significantly improves the performance of the scavenger. Formation of solids is mostly inhibited which otherwise hampers the accessibility of part of the scavenger and furthermore bears the risk of clogging flow lines for the effluent. The enhancement in scavenging efficiency exceeds the stoichiometric H.sub.2S scavenging capacity of the added synergist considerably.