CA3028940A1

CA3028940A1 - Composition for removing iron sulfide

Info

Publication number: CA3028940A1
Application number: CA3028940A
Authority: CA
Inventors: Masaki Shimizu; Yuusuke SAITOU; Takuo Tsuruta; Junichi Fuji
Original assignee: Kuraray Co Ltd
Current assignee: Kuraray Co Ltd
Priority date: 2016-06-28
Filing date: 2017-06-21
Publication date: 2018-01-04
Also published as: SG11201811541TA; RU2018145752A3; JPWO2018003624A1; WO2018003624A1; TW201816098A; MX2018016415A; RU2018145752A; BR112018076690A2; EP3486353A1; US20190241822A1; EP3486353A4; CN109415819A

Abstract

Provided is a composition for removing iron sulfide, the composition containing an a,ß-unsaturated aldehyde represented by general formula (1) as an active ingredient (wherein: R1-R3 each independently represent a hydrogen atom, an alkyl group having 1-10 carbon atoms, an alkenyl group having 2-10 carbon atoms, or an aryl group having 6-12 carbon atoms; R1 may be bonded with R2 or R3 to form an alkylene group having 2-6 carbon atoms; and R1 and R2 would not simultaneously be hydrogen atoms).

Description

DESCRIPTION
Title of Invention COMPOSITION FOR REMOVING IRON SULFIDE
Technical Field [0001]
The present invention relates to a composition for removing iron sulfide and a method for removing iron sulfide, which includes using the same.
Background Art

[0002]
Hydrogen sulfide that often exists in hydrocarbons, such as fossil fuels and refined petroleum products, for example, natural gas, liquefied natural gas, sour gas, crude oil, naphtha, heavy aromatic naphtha, gasoline, kerosene, diesel oil, light oil, heavy oil, FCC slurry, asphalt, and oil field concentrates, corrodes iron which is used in excavation facilities, etc., to cause generation of iron sulfide. The iron sulfide is accumulated as a deposit within production facilities of fossil fuels and refined petroleum products, to lower operational efficiency of instruments in heat exchanger, cooling tower, reactor, transmission pipeline, furnace, etc., or disturb precise measurement for facility maintenance, and therefore, it is desired to remove this.

[0003]
As a method for removing iron sulfide, a method of dissolving iron sulfide with acrolein is known, and announcement regarding the removal of iron sulfide with acrolein as an active ingredient is also made in SPE Annual Technical Conference and Exhibition SPE 146080, held in the city of Denver, Colorado, USA on October 30 to November 2, 2011 (NPL 1). However, the acrolein is a compound which is strongly toxic and whose concentration is strictly regulated from the viewpoint of occupational safety and from the viewpoint of environmental safety, so that it involves such a problem that attention is required for handling. In addition to the above, the acrolein is problematic from the viewpoint that it is extremely easily polymerized and lacks in thermal stability and also from the viewpoint that it lacks in pH
stability, so that its abundance gradually decreases depending upon the pH of =
the environment to be used.
Citation List Non-Patent Literature

[0004]
NPL 1; SPE Annual Technical Conference and Exhibition SPE 146080, 2011; http://dx.doi.org/10.2118/146080-MS
Summary of Invention Technical Problem

[0005]
In the light of the above, in using acrolein for the purpose of removing iron sulfide, there are problems from the viewpoint of safety and thermal stability and also from the viewpoint of pH stability, and therefore, a safer and more stable compound is desired as a substitute therefor. Now, an object of the present invention is to provide a composition containing an active ingredient with high thermal stability and pH stability and being capable of removing iron sulfide safely and efficiently.
Solution to Problem

[0006]
In accordance with the present invention, the aforementioned object is achieved by the following [1] to [7].
[1] A composition for removing iron sulfide, containing, as an active ingredient, an a,p-unsaturated aldehyde represented by the following general formula (1) (hereinafter referred to as "aldehyde (1)");

[0007]

(1)

[0008]
wherein RI- to R3 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms, provided that R1 may be connected to R2 or R3, to constitute an alkylene group having 2 to 6 carbon atoms; and that R1 and R2 are not a hydrogen atom at the same time.
[2] The composition of [1], wherein R1 to R3 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
[3] The composition of [1] or [2], wherein R3 is a hydrogen atom.
[4] A method for removing iron sulfide, including bringing the composition of any of [1] to [3] into contact with iron sulfide.
[5] The method of [4], wherein the aldehyde (1) in the composition is added in an amount of 0.1 to 100 parts by mass based on 1 part by mass of iron sulfide.
[6] The method of [4] or [5], including bringing the aldehyde (1) in the composition into contact with iron sulfide in a range of from -30 C to 150 C.
[7] Use of the composition of any of [1] to [3], for removing iron sulfide.
Advantageous Effects of Invention

[0009]
Since the composition of the present invention contains the aldehyde (1), an excellent removal performance of iron sulfide is exhibited.
In particular, as compared with a conventional iron sulfide remover containing acrolein, the composition of the present invention has such an advantage that it is extremely low in toxicity and high in thermal stability and pH stability. Though the reasons for this are not elucidated yet, it may be considered as one of factors that since the aldehyde (1) has at least one of an alkyl group, an alkenyl group, and an aryl group at the f3-position thereof, an addition reaction to the 3-position of a bulky molecule, such as a biomolecule and a propagating chain, is hard to occur as compared with acrolein not having a substituent at the V-position thereof. Meanwhile, with respect to the removal of iron sulfide, it may be considered that the aldehyde (1) comes to bond to hydrogen sulfide that is existent in an equilibrium state with iron sulfide to thereby remove hydrogen sulfide, dissolution of iron sulfide is promoted, and as a result, the iron sulfide is removed; and while the aldehyde (1) has a substituent at the 13-position thereof, an attack from hydrogen sulfide that is in general a small molecule is not hindered so much, whereby the removal performance of iron sulfide is kept.
Brief Description of Drawings , =

[0010]
r ' Fig. 1 is a graph showing pH stability of senecioaldehyde (SAL).
Fig. 2 is a graph showing pH stability of acrolein.
Description of Embodiments

[0011]
The composition of the present invention includes the aldehyde (1) as an active ingredient.
In the aldehyde (1), the alkyl group having 1 to 10 carbon atoms, which Ri- to R3 each independently represent, may be linear, branched, or cyclic, and examples thereof include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a t-butyl group, a n-pentyl group, a n-hexyl group, a n-octyl group, a n-decyl group, a n-dodecyl group, and a cyclopentyl group. Above all, from the viewpoint of removal performance of iron sulfide, a methyl group, an ethyl group, or a n-propyl group is preferred, a methyl group or an ethyl group is more preferred, and a methyl group is still more preferred.
The alkenyl group having 2 to 10 carbon atoms, which R1 to R3 each independently represent, may be linear, branched, or cyclic, and examples thereof include a vinyl group, an allyl group, a 1-penten-1-y1 group, a 4-methyl-3-penten-1-y1 group, a 4-penten-1-y1 group, a 1-hexen-1-y1 group, a 1-octen-1-y1 group, and a 1-decen-1-y1 group. Above all, an alkenyl group having 1 to 8 carbon atoms is preferred, and an alkenyl group having 1 to 6 carbon atoms is more preferred.
Examples of the aryl group having 6 to 12 carbon atoms, which 11,1- to R3 each independently represent, include a phenyl group, a tolyl group, an ethylphenyl group, a xylyl group, a trimethylphenyl group, a naphthyl group, a biphenylyl group. Above all, an aryl group having 6 to 10 carbon atoms is preferred.
In the case where R1 is connected to R2 or R3, to constitute an alkylene group having 2 to 6 carbon atoms, examples of the alkylene group include an ethylene group, a n-propylene group, a n-butylene group, a n-pentylene group, a hexylene group, a 2-methylethylene group, a 1,2-dimethylethylene group, a 2-methyl-n-propylene group, a 2,2-dimethyl-n-propylene group, and a 3-methyl-n-pentylene group.

It is preferred that RI- to R3 are each independently a hydrogen atom or , an alkyl group having 1 to 5 carbon atoms.
From the viewpoint of exhibiting removal performance of iron sulfide and keeping thermal stability and pH stability, it is preferred that at least one of RI- and R2 is a methyl group, and it is still more preferred that both RI-and R2 are a methyl group.
From the viewpoint of promoting the reaction with hydrogen sulfide and efficiently removing iron sulfide, it is preferred that R3 is a hydrogen atom.

[0012]
Examples of the aldehyde (1) include 2-butenal, 2-pentenal, 2-hexenal, 2-heptenal, 2-octenal, 2-nonenal, 2-decenal, 2-undecenal, 2-dodecenal, 2-tridecenal, 4-methyl-2-pentenal, 4-methyl-2-hexenal, 5-methyl-2-hexenal, 4,4-dimethy1-2-pentenal, 6-mehy1-2-heptenal, 4-ethyl-2-hexenal, 2-methyl-2-butenal, 2-methyl-2-pentenal, 2-methyl-2-hexenal, 2-methyl-2-heptenal, 2-methy1-2-octenal, 4-methyl-2-propy1-2-hexenal, 2,4-dimethy1-2-pentenal, 2,4-dimethy1-2-hexenal, 2,4-dimethy1-2-heptenal, 2,5-dimethy1-2-hexenal, 2,6-dimethy1-2-heptenal, 2,4,4-trimethy1-2-pentena1, 2-ethyl-2-butenal, 2-ethyl-2-pentenal, 2-ethyl-2-hexenal, 2-ethyl-2-heptenal, 2-ethyl-2-octenal, 2-ethyl-4-methyl-2-pentenal, 2-ethyl-4-methy1-2-hexenal, 2-propy1-2-butenal, 2-propy1-2-pentenal, 2-propy1-2-hexenal, 2-propy1-2-heptenal, 2-propy1-4-methyl-2-pentenal, 2-propy1-5-methy1-2-hexenal, 2-isopropyl-2-butenal, 2-isopropyl- 4-methyl- 2-pe ntenal, 2-isopropyl-4-methyl-2-hexenal, 2-isopropyl- 5- methy1-2-hexenal, 2-butyl-2-butenal, 2 -buty1-2-pentenal, 2-butyl-2-hexenal, 2-butyl-2-heptenal, 2-butyl-2-octenal, 2-isobuty1-2-heptenal, 2-isobuty1-6-methyl-2-heptenal, 2-penty1-2-butenal, 2-penty1-2-pentenal, 2-penty1-2-hexenal, 2-penty1-2-heptenal, 2-penty1-2-octenal, 3-methyl-2-butenal, 3-methyl-2-pentenal, 3-methyl-2-hexenal, 3-methyl-2-heptenal, 3-methyl-2-octenal, 3-methyl-2-nonenal, 3-methyl-2-decenal, 3-methyl-2-undecenal, 3-methy1-2-dodecena1, 3-methy1-2-tridecena1, 3-ethyl-2-pentenal, 3,4-dimethy1-2-pentenal, 3,4,4-trimethy1-2-pentenal, 3-isopropy1-4-methy1-2-pentena1, 3-ethyl-2-hexenal, 3-propy1-2-hexenal, 3,5-dimethy1-2-hexenal, 3-(t-butyl) -4,4-dimethy1-2-pentenal, 3-butyl-2-heptenal, 2,3-dimethy1-2-butenal, 2-ethy1-3-methy1-2-butena1, =
2-isopropyl- 3-methy1-2-butena1, 2, 3- dimethy1-2-pentenal, 2,3, 4-trimethy1-2 -hexenal, 2-isobutyl- 3-methyl- 2-butenal, 3-methyl- 2-p entyl- 2-pentenal, 2,3-diethyl- 2-heptenal, 2-(1,1-dimethylpropy1)-3-methy1-2-butenal, 3, 5,5-trimethyl- 2-hexenal, 2,3,4-trimethy1-2-pentena1, 2-cyclopropylpyridenepropanal, 2-cyclopentylidenepropanal, 2-cyclopentylidenehexanal, 2- (3- methylcyclopentylidene)prop anal, 2-cyclohexylidienepropanal, 2-(2-methylcyclohexylidene)propanal, 2-cyclohexylidenebutanal, 2-cyclohexylidenehexanal, 1-formylcyclobutene, 1- formyl- 3,3 - dimethylcyclobutene, 1-cyclopropy1-2-formylcyclobutene, 1- formylcyclop entene, 5-ethyl- 1-formylcyclopentene, 1- formyl- 3- methylcyclopentene, 1-formy1-4-methylcyclopentene, 1-formyl- 5 -methylcyclopentene, 1-formyl- 3, 3- dimethylcyclopentene, 1-formyl- 4,5- dimethylcyclopentene, 1-formyl- 2-methylcyclopentene, 1-formyl- 5 -isopropyl- 2-methylcyclopentene, 1-formyl- 2, 5, 5 -trimethylcyclopentene, 1-formylcyclohexene, 1-formyl- 3- methylcyclohexene, 1-formyl-4-methylcyclohexene, 1-formyl-5-methylcyclohexene, 1-formyl- 6- methylcyclohexene, 1-formyl- 3,3- dimethylcyclohexene, 1-formyl-5,5-dimethylcyclohexene, 1-formyl- 2 -methylcyclohexene, 1-formy1-2, 5,6, 6-tetramethylcyclohexene, 1-formy1-2,4,6,6-tetramethylcyclohexene, 1-formylcycloheptene, 1-formyl- 2- methylcycloheptene, 1-formyl- 3- methylcycloheptene , 1-formylcyclooctene, 2,4-pentadienal, 2,4-hexadienal, 2,5-hexadienal, 5-methyl- 2, 4-hexadienal, 2, 4-heptadienal, 2, 4-octadienal, 2, 7-octadienal, 3,7 - dimethyl- 2,6- octadienal (citral), 2,4,6-octatrienal, 7-methyl-2,4,6-octatrienal, 2,4-nonadienal, 2,6-nonadienal, 4,8- dimethy1-2,7-nonadienal, 2,4-decadienal, 2,4-undecadienal, 2,4-dodecadienal, 2,4-tridecadienal, 2,4,7-tridecatrienal, 3-phenylpropenal, 3-phenyl-2-methylpropenal, 3-(o-tolyl)propenal, 3-(p-tolyl)propenal, and 3-napthylpropenal. Above all, 3-methyl-2-butenal, 3-methyl-2-pentenal, 3 -methyl- 2 - hexenal, 3-methy1-2-heptena1, 3-methyl-2-octenal, 3,7-dimethy1-2,6-octadienal (citral), 3-ethyl-2-pentenal, 3-ethyl-2-hexenal, and 3-propy1-2-hexenal are preferred; 3-methyl-2-butenal, 3-methyl-2-pentenal, and 3-ethyl-2-pentenal are more preferred; and 3-methyl-2-butenal (senecioaldehyde, hereinafter referred to simply as "SAL") is still more preferred.
With respect to compounds having a trans-isomer and a cis-isomer, either one of them may be used, or a mixture of the both isomers may also be used. In the case of using a mixture, those having an arbitrary mixing ratio can be used.

[0013]
As for the aldehyde (1), a commercially available product may be used, or it may be synthesized through an oxidative dehydrogenation reaction of a corresponding a,13-unsaturated alcohol (see, for example, JP 60-224652 A).

[0014]
Though a content proportion of the aldehyde (1) that is an active ingredient in the composition of the present invention can be properly set according to the use embodiment, it is typically 1 to 99.9% by mass, and from viewpoint of cost-effectiveness, it is preferably 5 to 99.9% by mass, and more preferably 5 to 95% by mass.

[0015]
The composition of the present invention may contain other iron sulfide remover, such as acrolein, tetrakis(hydroxymethyl)phosphine or a corresponding phosphonium salt, hydrochloric acid, and formic acid, as long as the effects of the present invention are not impaired.
The composition of the present invention may contain an appropriate solvent, such as cyclohexane, toluene, xylene, a heavy aromatic naphtha, and a petroleum distillate; and a monoalcohol or dialcohol having 1 to 10 carbon atoms, e.g., methanol, ethanol, and ethylene glycol.

[0016]
The composition of the present invention may contain, in addition to the aldehyde (1), a component, such as a surfactant, a corrosion inhibitor, an oxygen scavenger, an iron control agent, a crosslinking agent, a breaker, a coagulant, a temperature stabilizer, a pH adjuster, a dehydration regulator, a swelling prevention agent, a scale inhibitor, a biocide, a friction reducer, a defoaming agent, an agent for preventing a lost circulation of mud water, a lubricating agent, a clay dispersant, a weighting agent, and a gelling agent, as long as the effects of the present invention are not impaired.

[0017]
The composition of the present invention is not particularly limited . .
with respect to its production method, and it can be, for example, produced by , , adding and mixing the aldehyde (1) with the aforementioned arbitrary component, such as an iron sulfide remover and a solvent.
Though the composition of the present invention is suitably a liquid, it may be converted in a solid form, such as a powder and a fluid, upon being properly supported on a carrier, etc., according to a form to be used for the purpose of removing iron sulfide.

[0018]
As a preferred embodiment of the present invention, the treatment is performed by adding the composition of the present invention in an amount sufficient for the removal of iron sulfide to a liquid containing iron sulfide. In the method of removing iron sulfide by using the composition of the present invention, the composition of the present invention is added such that the amount of the aldehyde (1) contained in the composition of the present invention is preferably 0.1 to 100 parts by mass, and more preferably 2 to 100 parts by mass based on 1 part by mass of iron sulfide. A temperature on the occasion of performing the treatment in which the composition of the present invention is added to and brought into contact with a liquid containing iron sulfide is preferably in a range of from 0 C to 150 C, and more preferably from 20 C to 130 C.
Examples

[0019]
The present invention is hereunder specifically described by reference to Examples and the like, but it should be construed that the present invention is by no means limited by the following Examples. SAL, citral, and acrolein used in the Examples and Comparative Example are those mentioned below.
SAL: One synthesized from prenol in conformity with the method described in JP 60-224652 A (purity: 98.1%) Citral: Product available from Kuraray Co., Ltd. (purity: 98.0%, trans/cis = 51/49 to 57/43 (molar ratio)) Acrolein: Product available from Tokyo Chemical Industry Co., Ltd., which contains hydroquinone as a stabilizer

[0020]
<Example 1> Removal Test of Iron Sulfide (SAL) In a 1L three-necked flask equipped with a thermometer, a stirrer, and a condenser, 500 mL of distilled water, 1 mL of 1 mol/L hydrochloric acid, 120.0 mg (0.5 mmol) of sodium sulfide nonahydrate, and 138.2 (0.5 mmol) of iron sulfate heptahydrate were added and stirred. As a result, iron sulfide was produced as a fine black precipitate. 126.3 mg (1.5 mmol) of SAL was added thereto, and the reaction solution was subjected to temperature rise to 50 C
while stirring at 500 rpm. The point of time at when SAL was added was defined as 0 hour, and the behavior of iron sulfide was observed. As a result, after elapsing 4 hours, the iron sulfide was dissolved, and the reaction solution became colorless transparent.

[0021]
<Example 2> Removal Test of Iron Sulfide (Citral) The same test as in Example 1 was carried out, except that citral was used in place of SAL. After elapsing 7 hours, iron sulfide was dissolved, and the reaction solution became colorless transparent.

[0022]
<Comparative Example 1> Removal Test of Iron Sulfide (Acrolein) The same test as in Example 1 was carried out, except that acrolein was used in place of SAL. After elapsing 4 hours, iron sulfide was dissolved, and the reaction solution became colorless transparent.

[0023]
<Test Example 1> Thermal Stability Test 50 mL of each of SAL and acrolein was charged in three-necked flask, and the contents were subjected to temperature rise to 50 C in a nitrogen atmosphere. On the occasion when the content of each of SAL and acrolein immediately after the temperature rise was defined as 100%, a change of the content ratio was observed according to the calibration curve method by means of gas chromatography with an internal standard. The results are shown in Table 1.

[0024]
[Gas Chromatography Analysis]
Analysis instrument: GC-14A (available from Shimadzu Corporation) Detector: FID (hydrogen flame ionization detector) Column used: DB-1701 (length: 50 m, film thickness: 1 1.im, inner diameter: 0.32 mm) (available from Agilent Technologies) Analysis conditions: Injection temperature: 250 C, detection temperature: 250 C
Temperature rise conditions: 70 C ¨> (temperature rise at 5 C/min) ¨>

Internal standard substance: Diglyme (diethylene glycol dimethyl ether)

[0025]
Table 1: Results of thermal stability test 0 h 2 hours 4 hours 6 hours 10 hours our elapsed elapsed elapsed elapsed SAL 100.0% 100.0% 100.0% 100.0% 99.9%
Acrolein 100.0% 99.5% 98.3% 98.1% 96.6%

[0026]
After elapsing 10 hours, SAL remained in a ratio of 99.9%, whereas nevertheless acrolein contained hydroquinone as a stabilizer, it was lost in a ratio of 3.4%. It is noted from these results that SAL is extremely high in the thermal stability as compared with acrolein.

[0027]
<Test Example 2> pH Stability Test Each of SAL and acrolein was dissolved in 0.5 mol/L of phosphoric acid buffer solutions having a pH different from each other, thereby preparing 0.1 wt% solutions. 50 mL of each of the solutions was charged in a sample vial in a nitrogen atmosphere and stored at 23 2 C. On the occasion when the content of each of SAL and acrolein at the time of preparation was defined as 100%, a change of the content ratio was observed according to the absolute calibration curve by means of high-performance liquid chromatography analysis. The results are shown in Figs. 1 and 2.
It is noted from these results that SAL is extremely high in the pH
stability as compared with acrolein.

[0028]
[Preparation of Phosphoric Acid Buffer Solution]
pH 1.7: 4.9 g of 75% phosphoric acid and 7.8 g of sodium dihydrogen phosphate dihydrate were dissolved in 200 mL of distilled water.
pH 6.2: 7.8 g of sodium dihydrogen phosphate dihydrate and 7.1 g of disodium hydrogen phosphate were dissolved in 200 mL of distilled water.

pH 8.1: 0.3 g of sodium dihydrogen phosphate dihydrate and 13.9 g of disodium hydrogen phosphate were dissolved in 200 mL of distilled water.

[0029]
[High-Performance Liquid Chromatography Analysis]
Analysis instrument: Prominence System (available from Shimadzu Corporation) Column used: Cadenza CD-C18 (length: 150 m, inner diameter: 4.6 mm) Developing solution: H20/Me0H = 45/55 (volume ratio), H3PO4 = 1 mol/L
Flow rate: 1 mL/min

[0030]
<Reference Example>
SAL, citral, and acrolein are each an existing compound, and the information regarding the safety is disclosed. For reference, the information regarding the safety is shown in Table 2. SAL and citral are extremely low in the toxicity and safe as compared with acrolein.

[00311 Table 2: Information regarding safety of SAL, citral, and acrolein SAL Citral Acrolein Category IV, Class II petroleum Category IV, Class III petroleum Category IV, Class I petroleum Fire Service Act Hazardous grade III, water-insoluble Hazardous grade III, water-insoluble Hazardous grade II, water-insoluble Poisonous and Deleterious Substances Control Law Not applicable Not applicable Poisonous substance United Nations Classification Class 3 (inflammable liquid) Not applicable Class 6.1 (poisonous substance) Acute toxicity Rat LD50: 690 mg/kg Rat LD50:
4,960 mg/kg Rat LD50: 42 mg/kg GHS Classification; Section 1 (upper 0.1 ppm Respiratory organs, nervous system, Permissible Exposure Limit respiratory tract) No information and liver are considered to be target Irritative symptom in respiratory tract at organs 100 ppm or more Anesthetic action .
,õ
,õ
,õ

[00321 It is noted from the aforementioned Examples, Comparative Example, and Reference Example that the aldehyde (1), such as SAL, has an iron sulfide removal ability equivalent to acrolein and is higher in the thermal stability and the pH stability and safer than acrolein.
Industrial Applicability [0033]
The composition of the present invention is useful in view of the fact that it is high in the thermal stability and the pH stability and is able to remove iron sulfide safely and efficiently.

Claims

14

[Claim 1]
A composition for removing iron sulfide, comprising, as an active ingredient, an .alpha.,.beta.-unsaturated aldehyde represented by the following general formula (1);
wherein R1 to R3 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms, provided that R1 may be connected to R2 or R3, to constitute an alkylene group having 2 to 6 carbon atoms; and that R1 and R2 are not a hydrogen atom at the same time.
[Claim 2]
The composition according to claim 1, wherein R1 to R3 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
[Claim 3]
The composition according to claim 1 or 2, wherein R3 is a hydrogen atom.
[Claim 4]
A method for removing iron sulfide, comprising bringing the composition of any of claims 1 to 3 into contact with iron sulfide.
[Claim 5]
The method according to claim 4, wherein the .alpha.,.beta.-unsaturated aldehyde in the composition is added in an amount of 0.1 to 100 parts by mass based on part by mass of iron sulfide.
[Claim 6]
The method according to claim 4 or 5, comprising bringing the .alpha.,.beta.-unsaturated aldehyde in the composition into contact with iron sulfide in a range of from -30°C to 150°C.
[Claim 7]
Use of the composition according to any of claims 1 to 3, for removing iron sulfide.