Mixed inhibitory corrosion inhibitor and preparation method thereof

Abstract

The invention discloses a mixed inhibitory corrosion inhibitor and a preparation method thereof. The mixed inhibitory corrosion inhibitor comprises the following components in percentage by mass: 10%-30% of cationic imidazoline, 1%-30% of acylthiourea and 40%-89% of a solvent, the cationic imidazoline is synthesized from organic acid and organic amine in the presence of a catalyst; the acylthiourea is prepared by taking organic acid, thiocyanate and organic amine as raw materials. According to a multi-adsorption-center imidazoline and acylthiourea formula system formed by the invention, a protective film is formed in a physical adsorption and chemical adsorption manner, so that the anode process of a corrosion reaction that a sulfuration corrosion product iron ion is diffused into a solution is effectively prevented; the cathode process of the corrosion reaction that hydrogen ions in the solution migrate to metal is inhibited through the covering effect, and the method can be used for corrosion protection of a crude oil gathering and transportation system with the high content of H2S / CO2.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, and in particular to a mixed inhibitory corrosion inhibitor in a high hydrogen sulfide system and a preparation method thereof. Background Art

[0002] With the exploitation of oil and gas fields, the H2S content in some oil fields is relatively high, up to 2Mpa in a corrosive medium environment. Although there are a large number of literatures and patents reporting corrosion inhibitors for H2S and CO2 systems, which can control the corrosion of carbon steel when the H2S content is less than 2000ppm, it is difficult to achieve corrosion control under high H2S and high flow rates. Therefore, it is of great significance to develop a mixed inhibitory corrosion inhibitor. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a mixed inhibitory corrosion inhibitor and a preparation method thereof. The corrosion inhibitor is used in a crude oil gathering and transportation system with a high H2S (2.0Mpa) / CO2 content, and the film-forming strength of the corrosion inhibitor is improved by simultaneous inhibition of the cathode and anode, thereby improving the corrosion inhibition effect of the corrosion inhibitor.

[0004] In a first aspect, the present invention provides a mixed inhibitory corrosion inhibitor, which is realized by adopting the following technical solution.

[0005] A mixed inhibitory corrosion inhibitor comprises the following components in mass percentage: 10-30% of cationic imidazoline, 1-30% of acyl thiourea and 40%-89% of solvent; the cationic imidazoline is synthesized from organic acid and organic amine under catalyst conditions; the acyl thiourea is prepared from organic acid, thiocyanate and organic amine as raw materials.

[0006] Furthermore, the solvent is selected from one of ethanol, methanol, isopropanol and ethylene glycol.

[0007] Furthermore, the synthesis method of the cationic imidazoline comprises the following steps:

[0008] a. Under nitrogen protection, the organic acid and the organic amine are mixed in a molar ratio of 1:0.8-1.5, and a benzene solvent is added;

[0009] b. Reflux at 120°C to 140°C for 1h to 4h to separate the water generated by the amidation reaction; then keep the temperature at 140°C to 210°C for 1h to 2h to evaporate the solvent and unreacted raw materials, then cool to 70 to 100°C, add a catalyst, control the reaction temperature at 110°C to 130°C, and react for 2h to 4h to obtain an imidazoline intermediate;

[0010] c. Adding solvent and quaternizing agent for modification, reacting at 70°C to 80°C for 4h to 6h, cooling the reactant to obtain cationic imidazoline;

[0011] The specific reaction formula is as follows:

[0012]

[0013] Wherein, R1=-Ph, cycloalkyl, -C 11 H 23 、-C8H 17 , -C 15 H 31 , heptadeca-9-enyl, cis-hexadeca-13-enyl;

[0014] n=0, 1, 2, 3, corresponding to the organic amines ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, respectively.

[0015] Furthermore, the catalyst is selected from one or more of p-toluenesulfonyl chloride, methanesulfonyl chloride, methanesulfonic acid, trifluoromethanesulfonic acid, and phosphorus pentoxide, mixed in any proportion.

[0016] Furthermore, the amount of the catalyst used accounts for 5 mol% to 10 mol% of the amount of the organic amine fed.

[0017] Furthermore, the quaternizing agent is selected from one of methyl chloride, benzyl chloride, dimethyl sulfate, dimethyl carbonate, and dimethyl phosphite. Specifically, when the quaternizing agent is methyl chloride or benzyl chloride, R2 = methyl or benzyl, and X = Cl - ; When the quaternizing agent is dimethyl sulfate, dimethyl carbonate, dimethyl phosphite, R2 = methyl, X = CH3SO4 - , CH3CO3 - , CH3PHO3 - .

[0018] Furthermore, the molar ratio of the imidazoline intermediate to the quaternary ammonium agent is 1:(1.0-1.2).

[0019] Furthermore, the benzene solvent is toluene or xylene; the mass ratio of the reactant to the benzene solvent is 1:0.5-1.

[0020] Furthermore, in step c, the solvent is selected from one of ethanol, methanol and isopropanol.

[0021] Further, the synthesis method of the acyl thiourea comprises the following steps:

[0022] The acyl chloride and dichloromethane solvent are mixed in a mass ratio of 1:0.5-1, and thiocyanate is added in batches under stirring conditions at 0°C to 10°C, with the molar ratio of thiocyanate to acyl chloride being 0.9-1.2:1, and the mixture is stirred for reaction for 0.5-2h; then, an organic amine is added at 10°C to 40°C, with the molar ratio of the organic amine to acyl chloride being 0.9-1.2:1, and the mixture is stirred for reaction for 0.5-2h, and the solvent is evaporated under reduced pressure to obtain acyl thiourea;

[0023] The specific reaction formula is as follows:

[0024]

[0025] Wherein, R1=-phenyl, cycloalkyl, -C 11 H 23 、-C8H 17 , -C 15 H 31 , heptadeca-9-enyl, cis-hexadeca-13-enyl;

[0026] X=Cl, Br;

[0027] M=K, Na, NH4;

[0028] R3 = -CH2CH2OH, -phenyl, lauryl, -CH2CH2OCH2CH2OH.

[0029] In a second aspect, the present invention provides a method for preparing a mixed inhibitory corrosion inhibitor, which is achieved by adopting the following technical solution.

[0030] A method for preparing the mixed inhibitory corrosion inhibitor comprises stirring and mixing a specified amount of cationic imidazoline, acylthiourea and solvent to obtain the mixed inhibitory corrosion inhibitor.

[0031] This application has the following beneficial effects.

[0032] The multi-adsorption center imidazoline and acylthiourea formula system formed by the present invention forms a protective film by means of physical adsorption and chemical adsorption, effectively preventing the anodic process of the corrosion reaction in which the sulfidation corrosion product iron ions diffuse into the solution, and inhibiting the cathodic process of the corrosion reaction in which the hydrogen ions in the solution migrate to the metal through the covering effect, thereby effectively solving the problem of corrosion inhibition performance under the condition of excess hydrogen sulfide. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the infrared spectrum of the uncatalyzed cyclized imidazoline product in Example 1 of the present invention. -1 There is an imidazoline characteristic absorption peak at 1560.82cm -1 There are characteristic absorption peaks of unconverted amides;

[0034] Figure 2 This is the infrared spectrum of the catalytic cyclization imidazoline product in Example 1 of the present invention. After the catalytic reaction, -1 There is an obvious imidazoline characteristic absorption peak at 1560.82cm -1 The amide disappears and is converted into imidazoline. DETAILED DESCRIPTION

[0035] The present patent application is further described below in conjunction with embodiments.

[0036] Unless otherwise specified, the experimental methods used in the following preparation examples and examples are all conventional methods; the materials, reagents, etc. used in the following preparation examples and examples are all commercially available unless otherwise specified.

[0037] Example 1

[0038] Step 1: Synthesis of cationic imidazoline

[0039] Under nitrogen protection, an organic acid and an organic amine are accurately weighed in sequence into a four-necked flask equipped with a thermometer, a stirrer, a condenser and a water separator, and the molar ratio thereof is 1:1.5. At the same time, a dry benzene solvent is added to the reactor, and the mass ratio of the reactant to the benzene solvent is 1:1. The temperature is raised to 135°C and refluxed for 4 hours to separate the water generated by the amidation reaction. The temperature is then gradually raised to 210°C and kept for 2 hours to evaporate the solvent and the unreacted raw materials, and then the temperature is lowered to 70°C, and then a catalyst is slowly added, and the reaction temperature is controlled at 110°C. After reacting for 2 hours, an imidazoline intermediate is obtained, and finally ethanol and a quaternary ammonium agent are added for modification. After reacting at 80°C for 4 hours, the reactant is cooled to obtain a cationic imidazoline.

[0040] The specific reaction formula is as follows:

[0041]

[0042] Where: R1 = -Ph;

[0043] n=0, the corresponding organic amine is ethylenediamine;

[0044] The benzene solvent is xylene;

[0045] The catalyst is p-toluenesulfonyl chloride, and the amount of the catalyst used is 5 mol% of the amount of the organic amine fed;

[0046] The quaternizing agent is benzyl chloride; R2 = benzyl, X = Cl - ;

[0047] The reaction molar ratio of imidazoline intermediate: quaternary ammonium agent = 1:1.2.

[0048] Step 2: Synthesis of acylthiourea

[0049] To a four-necked flask equipped with a thermometer, a stirrer and a condenser, add acyl chloride and dichloromethane solvent in sequence, the mass ratio of acyl chloride to dichloromethane solvent is 1:1, turn on mechanical stirring, add thiocyanate to the reactor in batches at 0°C, the molar ratio of thiocyanate to acyl chloride is 0.9:1, stir and react for 2 hours at this temperature, finally add organic amine at 10°C, the molar ratio of organic amine to acyl chloride is 0.9:1, stir and react for 2 hours at this temperature, and evaporate the solvent under reduced pressure to obtain acyl thiourea.

[0050] The specific reaction formula is as follows:

[0051]

[0052] Where: R1 = -Ph;

[0053] M is K;

[0054] X is Cl;

[0055] R3=-CH2CH2OH.

[0056] Step 3: The mixed inhibitory corrosion inhibitor is a product in which the mass proportion of cationic imidazoline is 30%, the mass proportion of acyl thiourea is 10%, and the mass proportion of ethanol is 60%, and the mixture is stirred.

[0057] Example 2

[0058] Step 1: Synthesis of cationic imidazoline

[0059] Under nitrogen protection, an organic acid and an organic amine are accurately weighed in sequence into a four-necked flask equipped with a thermometer, a stirrer, a condenser and a water separator, and the molar ratio thereof is 1:0.8. At the same time, a dry benzene solvent is added to the reactor, and the mass ratio of the reactant to the benzene solvent is 1:0.5; the temperature is raised to 140°C and refluxed for 1 hour to separate the water generated by the amidation reaction; the temperature is gradually raised to 210°C and kept for 2 hours to evaporate the solvent and the unreacted raw materials, and then the temperature is lowered to 100°C, and then a catalyst is slowly added, and the reaction temperature is controlled at 110°C. After reacting for 2 hours, an imidazoline intermediate is obtained, and finally ethanol and a quaternary ammonium agent are added for modification. After reacting at 80°C for 4 hours, the reactant is cooled to obtain a cationic imidazoline;

[0060] The specific reaction formula is as follows:

[0061]

[0062] Wherein: R1 = cycloalkyl;

[0063] n=1, the corresponding organic amine is diethylenetriamine;

[0064] The benzene solvent is xylene;

[0065] The catalyst is p-toluenesulfonyl chloride, and the amount of the catalyst used is 10 mol% of the amount of the organic amine fed;

[0066] The quaternizing agent is benzyl chloride; R2 = benzyl, X = Cl - ;

[0067] The reaction molar ratio of imidazoline intermediate: quaternary ammonium agent = 1:1.2.

[0068] Step 2: Synthesis of acylthiourea

[0069] To a four-necked flask equipped with a thermometer, a stirrer and a condenser, add acyl chloride and dichloromethane solvent in sequence, the mass ratio of acyl chloride to dichloromethane solvent is 1:0.5, turn on mechanical stirring, add thiocyanate to the reactor in batches at 0°C, the molar ratio of thiocyanate to acyl chloride is 1.2:1, at this temperature, stir and react for 0.5h, finally add organic amine at 40°C, the molar ratio of organic amine to acyl chloride is 1.2:1, at this temperature, stir and react for 2h, and evaporate the solvent under reduced pressure to obtain acyl thiourea.

[0070] The specific reaction formula is as follows:

[0071]

[0072] Wherein: R1 = cycloalkyl;

[0073] M is K;

[0074] X is Cl;

[0075] R3=-CH2CH2OH;

[0076] Step 3: The mixed inhibitory corrosion inhibitor is a product in which the mass proportion of cationic imidazoline is 30%, the mass proportion of acyl thiourea is 10%, and the mass proportion of ethanol is 60%, and the mixture is stirred.

[0077] Example 3

[0078] Step 1: Synthesis of cationic imidazoline

[0079] Under nitrogen protection, an organic acid and an organic amine are accurately weighed in sequence into a four-necked flask equipped with a thermometer, a stirrer, a condenser and a water separator, and the molar ratio thereof is 1:1. At the same time, a dry benzene solvent is added to the reactor, and the mass ratio of the reactant to the benzene solvent is 1:1; the temperature is raised to 120°C and refluxed for 2 hours to separate the water generated by the amidation reaction; the temperature is gradually raised to 210°C and kept for 2 hours to evaporate the solvent and the unreacted raw materials, and then the temperature is lowered to 80°C, and then a catalyst is slowly added, and the reaction temperature is controlled at 110°C. After reacting for 2 hours, an imidazoline intermediate is obtained, and finally ethanol and a quaternary ammonium agent are added for modification. After reacting at 80°C for 4 hours, the reactant is cooled to obtain a cationic imidazoline;

[0080] The specific reaction formula is as follows:

[0081]

[0082] Wherein: R1=-heptadeca-9-enyl;

[0083] n=1, the corresponding organic amine is diethylenetriamine;

[0084] The benzene solvent is xylene;

[0085] The catalyst is p-toluenesulfonyl chloride, and the amount of the catalyst used is 5 mol% of the amount of the organic amine fed;

[0086] When the quaternizing agent is benzyl chloride; R2 = benzyl, X = Cl - ;

[0087] The reaction molar ratio of imidazoline intermediate: quaternary ammonium agent = 1:1.2.

[0088] Step 2: Synthesis of acylthiourea

[0089] To a four-necked flask equipped with a thermometer, a stirrer and a condenser, add acyl chloride and dichloromethane solvent in sequence, the mass ratio of acyl chloride to dichloromethane solvent is 1:1, turn on mechanical stirring, add thiocyanate to the reactor in batches at 10°C, the molar ratio of thiocyanate to acyl chloride is 0.9:1, stir and react for 2 hours at this temperature, finally add organic amine at 40°C, the molar ratio of organic amine to acyl chloride is 0.9:1, stir and react for 2 hours at this temperature, and evaporate the solvent under reduced pressure to obtain acyl thiourea.

[0090] The specific reaction formula is as follows:

[0091]

[0092] Wherein, R1=-Ph;

[0093] M is K;

[0094] X is Cl;

[0095] R3=-phenyl;

[0096] Step 3: The mixed inhibitory corrosion inhibitor is a product in which the mass proportion of cationic imidazoline is 30%, the mass proportion of acyl thiourea is 10%, and the mass proportion of ethanol is 60%, and the mixture is stirred.

[0097] Comparative Example 1

[0098] Benzyl chloride oleic acid diethylenetriamine imidazoline (the preparation method thereof: add accurately weighed oleic acid 1 mol and diethylenetriamine 1 mol into a reactor in sequence, and at the same time add 500 mL of dry toluene into the reactor as a solvent, reflux at 120° C. for 2 hours, gradually heat up to 180° C., react for 2 hours, separate the water generated by the amidation reaction and evaporate the solvent, and then react at 260° C. for 4 hours, cool the reactant to obtain imidazoline, and then add isopropanol, and at a certain temperature, add benzyl chloride dropwise into the reactor, stir the reaction at this temperature for a certain time, and cool to obtain a brown-red imidazoline quaternary ammonium salt liquid) by mass accounting for 30%, thiourea accounting for 10%, and ethanol accounting for 60%, and mixing and stirring to obtain Comparative Example 1.

[0099] Comparative Example 2

[0100] Benzyl chloride benzoic acid diethylenetriamine imidazoline (its preparation method: add accurately weighed benzoic acid 1mol and diethylenetriamine 1mol into a reactor in sequence, and add 500mL of dry toluene into the reactor as a solvent at the same time, reflux at 120°C for 2h, gradually heat up to 160°C, react for 2h, separate the water generated by the amidation reaction and evaporate the solvent, and then react at 240°C for 4h, cool the reactant to obtain imidazoline, then add isopropanol, and at a certain temperature, add benzyl chloride dropwise into the reactor, stir the reaction at this temperature for a certain time, cool to obtain a brown-red imidazoline quaternary ammonium salt liquid) accounts for 30% by mass, thiourea accounts for 10%, and ethanol accounts for 60%, and mixing and stirring to obtain Comparative Example 2.

[0101] Performance Evaluation

[0102] Experimental medium: simulated water quality of an offshore oil field (mineralization 50000mg / L)

[0103] Experimental temperature: 76℃

[0104] Drug concentration: 30mg / L

[0105] Hanging material: X65 carbon steel

[0106] Evaluation standard: SY / T 5273 "Evaluation method for corrosion inhibitor performance of oilfield produced water"

[0107] Evaluation method:

[0108] Soak the steel test piece in anhydrous ethanol for about 5 minutes, take out the test piece, wipe it dry with filter paper, blow it dry with cold air, wrap it, put it in a desiccator to dry for 30 minutes, and weigh it (accurate to 0.0001g);

[0109] Pour 2L of water sample into the autoclave and add the corrosion inhibitor of the specified concentration in the experiment. Fix three test pieces in the polytetrafluoroethylene tank of the autoclave hanging system, install the autoclave, pass nitrogen and vacuum to remove oxygen in the autoclave in turn, and inject carbon dioxide and nitrogen of the specified pressure into the autoclave. Control the temperature to the experimental temperature, set the speed to 451rpm, and hang the dynamic piece for 72h. After heating to the specified temperature and running for 72 hours, observe the water color and the appearance of the steel sheet (brightness, film formation characteristics, local spots), treat with standard pickling solution and anhydrous ethanol, weigh, record, and calculate. The experimental results are shown in Table 1.

[0110] Table 1 Evaluation table of corrosion inhibitor performance of simulated water sample from an offshore oil field

[0111]

[0112]

[0113] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A mixed inhibitory corrosion inhibitor, characterized in that: The invention comprises the following components in mass percentage: 10-30% of cationic imidazoline, 1-30% of acyl thiourea and 40-89% of solvent; the cationic imidazoline is synthesized from organic acid and organic amine under catalyst condition; and the acyl thiourea is prepared from organic acid, thiocyanate and organic amine as raw materials.

2. A mixed inhibitory corrosion inhibitor according to claim 1, characterized in that: The synthesis method of the cationic imidazoline comprises the following steps: a. Under nitrogen protection, the organic acid and the organic amine are mixed in a molar ratio of 1:0.8-1.5, and a benzene solvent is added; b. Reflux at 120°C to 140°C for 1h to 4h to separate the water generated by the amidation reaction; then keep the temperature at 140°C to 210°C for 1h to 2h to evaporate the solvent and unreacted raw materials, then cool to 70 to 100°C, add a catalyst, control the reaction temperature at 110°C to 130°C, and react for 2h to 4h to obtain an imidazoline intermediate; c. Adding solvent and quaternizing agent for modification, reacting at 70°C to 80°C for 4h to 6h, cooling the reactant to obtain cationic imidazoline; The specific reaction formula is as follows: Wherein, R1=-Ph, cycloalkyl, -C 11 H 23 、-C8H 17 , -C 15 H 31 , heptadeca-9-enyl, cis-hexadeca-13-enyl; n＝0、1、2、3。 3. A mixed inhibitory corrosion inhibitor according to claim 2, characterized in that: The catalyst is selected from one or more of p-toluenesulfonyl chloride, methanesulfonyl chloride, methanesulfonic acid, trifluoromethanesulfonic acid, and phosphorus pentoxide, mixed in any proportion.

4. A mixed inhibitory corrosion inhibitor according to claim 2, characterized in that: The amount of the catalyst used accounts for 5 mol% to 10 mol% of the amount of the organic amine fed.

5. A mixed inhibitory corrosion inhibitor according to claim 2, characterized in that: The quaternizing agent is selected from one of methyl chloride, benzyl chloride, dimethyl sulfate, dimethyl carbonate and dimethyl phosphite.

6. A mixed inhibitory corrosion inhibitor according to claim 2, characterized in that: The molar ratio of the imidazoline intermediate to the quaternary ammonium agent is 1:(1.0-1.2).

7. A mixed inhibitory corrosion inhibitor according to claim 2, characterized in that: The benzene solvent is toluene or xylene; the mass ratio of the reactant to the benzene solvent is 1:0.5-1.

8. The mixed corrosion inhibitor according to claim 1, characterized in that: The synthetic method of the acyl thiourea comprises the following steps: The acyl chloride and dichloromethane solvent are mixed in a mass ratio of 1:0.5-1, and thiocyanate is added in batches under stirring conditions at 0°C to 10°C, with the molar ratio of thiocyanate to acyl chloride being 0.9-1.2:1, and the mixture is stirred for reaction for 0.5-2h; then, an organic amine is added at 10°C to 40°C, with the molar ratio of the organic amine to acyl chloride being 0.9-1.2:1, and the mixture is stirred for reaction for 0.5-2h, and the solvent is evaporated under reduced pressure to obtain acyl thiourea; The specific reaction formula is as follows: Wherein, R1=-phenyl, cycloalkyl, -C 11 H 23 、-C8H 17 , -C 15 H 31 , heptadeca-9-enyl, cis-hexadeca-13-enyl; X=Cl, Br; M=K, Na, NH4; R3 = -CH2CH2OH, -phenyl, lauryl, -CH2CH2OCH2CH2OH.

9. A method for preparing the mixed corrosion inhibitor according to any one of claims 1 to 8, characterized in that: A specified amount of cationic imidazoline, acylthiourea and solvent are stirred and mixed to obtain a mixed corrosion inhibitor.

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