Electrode dynamic modification protective agent and application thereof

Abstract

The invention relates to the technical field of oil and gas field chemical engineering, in particular to an electrode dynamic modification protective agent and application thereof. The electrode dynamic modification protective agent is prepared from the following components in parts by weight: 0 to 30 parts of benzotriazole and 10 to 200 parts of benzotriazole derivative; an aromatic ring of the benzotriazole derivative is provided with an alkyl substituent group, and the substitution position is at the fourth position or the fifth position. The electrode dynamic protective agent provided by the invention not only can improve the sensitivity of the indicator electrode, but also can inhibit the influence of the sulfur element on the electrolysis process, and the determination efficiency and accuracy are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field chemical engineering, and in particular to an electrode dynamic modification protective agent and application thereof. Background Art

[0002] Crude oil contains trace amounts of organic and inorganic chlorides. Inorganic chlorine mainly comes from formation water and can be removed by desalting and dehydrating. The main source of organic chlorine is various chemical additives containing organic chlorine used in oil field production. In the later refining process of crude oil, hydrogen chloride will be generated due to the hydrolysis and decomposition of chlorides. Hydrogen chloride is corrosive to equipment and will spread from the constant pressure reduction device to the secondary processing device. At the same time, chloride ions cause low-temperature dew point corrosion and salt formation problems, which in turn cause equipment corrosion and catalyst poisoning problems. The Shengli crude oil organic chlorine pollution accident in late May 2013 shows the importance of controlling the organic chlorine content in crude oil.

[0003] To determine the organic chlorine content in crude oil, foreign countries (the United States) adopt ASTM D4929-07 "Determination of Organic Chlorine Content in Crude Oil". China adopts GB / T 18612-2011 "Determination of Organic Chlorine Content in Crude Oil", and this standard is modified to adopt ASTM D4929-07. Shengli Oilfield adopts Q / SH1020 2466-2016 "Method for Determination of Organic Chlorine Content in Crude Oil". This method uses a micro-coulomb chlorine meter. The core component of the coulomb meter is the electrolytic cell. The electrolytic cell is composed of electrolyte + electrodes. There are four electrodes, namely the reference electrode, the measuring electrode, the cathode, and the anode; the electrolyte is composed of 70% glacial acetic acid + 30% pure water. Measurement principle: The sample is carried into the cracking tube by the carrier gas and fully burned with oxygen, and the chlorine in it is quantitatively converted into HCl. HCl is absorbed by the electrolyte and reacts: HCl+Ag + =AgCl↓+H + , the reaction consumes Ag in the electrolytic solution + , causing the change in the potential of the measuring electrode of the electrolytic cell. The instrument detects this change and gives the electrolytic electrode a corresponding voltage. Ag is electrolyzed on the electrode + , until Ag in the electrolytic cell + The instrument detects the amount of electricity consumed during the electrolysis process and estimates the amount of Ag consumed in the reaction. + The amount of Cl in the sample was obtained - The microcoulometric method for detecting organic chlorine in crude oil is currently a commonly used detection method in the oilfield development system and is also used for arbitration in the process of data disputes.

[0004] The current problems of this method are mainly manifested in three aspects: first, the variability of the measurement results is extremely large, and the analysis results cannot be accurately calculated when the precision is very poor (especially for samples with low organic chlorine content); second, the presence of sulfur has a great influence on the electrolysis process. In GB / T18612-2011 "Determination of Organic Chlorine Content in Crude Oil", it is clearly stated that "this standard is applicable to the determination of crude oil with an organic chlorine content greater than 1μg / g, and the combustion oxidation microcoulomb method is not applicable to crude oil with a total sulfur content greater than 10,000 times the organic chlorine content". Third, the existing electrolytic cell uses a saturated mercurous sulfate electrode, because the leakage of sulfate ions will lead to the generation of silver sulfate that interferes with the determination of chloride ions; at the same time, due to the high temperature of the electrolyte, the saturated potassium sulfate filling liquid in the reference electrode is easy to lose water and precipitate potassium sulfate crystals to block the column and lose conductivity. Summary of the invention

[0005] The main purpose of the present invention is to provide an electrode dynamic modification protective agent and its application. The electrode dynamic protective agent of the present invention can not only improve the sensitivity of the indicator electrode, but also inhibit the electrode acid hydrolysis, inhibit the influence of sulfur element on the electrolysis process, and avoid interference with the electrogenerated titrant ions.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides an electrode dynamic modification protective agent, which is composed of the following components and their weight parts: 0-30 parts of benzotriazole and 10-200 parts of benzotriazole derivatives; the aromatic ring of the benzotriazole derivative has an alkyl substituent, and the substitution position is at the 4th or 5th position.

[0008] The electrode dynamic modification protective agent of the present invention is a mixture of benzotriazole and its derivatives, the aromatic ring of the derivative has an alkyl substituent, the alkyl group contains 1-3 straight-chain carbon atoms, and the substitution position is at the 4th and 5th positions, which can play a dynamic modification and protection role on the silver electrode, not only can improve the sensitivity of the indicator electrode, but also can inhibit the acid decomposition of the electrode single substance, and avoid interference with the electrogenerated titrant ions. .

[0009] Furthermore, the substituent is a straight-chain alkyl substituent.

[0010] Furthermore, the benzotriazole derivative is one or more of 5-methyl-1H-benzotriazole, 4-methyl-1H-benzotriazole, 5-ethyl-1H-benzotriazole, 4-ethyl-1H-benzotriazole, 5-propyl-1H-benzotriazole, and 4-propyl-1H-benzotriazole.

[0011] Furthermore, the benzotriazole derivative is composed of the following components and their weight parts: 10-50 parts of 5-methyl-1H-benzotriazole, 0-50 parts of 4-methyl-1H-benzotriazole, 0-20 parts of 5-ethyl-1H-benzotriazole, 0-20 parts of 4-ethyl-1H-benzotriazole, 0-10 parts of 5-propyl-1H-benzotriazole, and 0-10 parts of 4-propyl-1H-benzotriazole.

[0012] The second aspect of the present invention provides an electrolyte, which is composed of the following components: an ethanol solution of the electrode dynamic modification protective agent described in the first aspect and a glacial acetic acid aqueous solution;

[0013] The concentration of the electrode dynamic modification protective agent ethanol solution is 1% (w / v)-5% (w / v).

[0014] Furthermore, the volume ratio of the ethanol solution of the electrode dynamic modification protective agent to the glacial acetic acid aqueous solution is 0.001-0.5.

[0015] The third aspect of the present invention provides the use of the electrode dynamic modification protective agent described in the first aspect or the electrolyte described in the second aspect in detecting the organic chlorine content of crude oil.

[0016] A fourth aspect of the present invention provides a method for detecting the organic chlorine content of crude oil by microcoulometric method, wherein the electrolytic cell used in the method adopts the electrolyte described in the second aspect above.

[0017] Furthermore, the electrolytic cell is also provided with a variable diameter porous plug sleeve, the electrolytic cell reference electrode is placed in the variable diameter porous plug sleeve, and the lower part of the variable diameter porous plug sleeve is placed in the reference arm; a salt bridge is provided at the lower end of the variable diameter porous plug sleeve, and the salt bridge and the reference electrode salt bridge form a double salt bridge structure.

[0018] Furthermore, a check valve is arranged inside the diameter of the air inlet of the electrolytic cell.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The electrode dynamic protective agent of the present invention can effectively inhibit the influence of sulfur element in the sample on the electrolysis process. At the same time, the electrode dynamic modification protective agent of the present invention plays a role in modifying and dynamically protecting the electrode (electrolysis anode and indicator electrode), inhibiting the reaction of electrode elements in acid, making the entire electrochemical reaction process stable, and greatly improving the measurement efficiency and accuracy.

[0021] The present invention improves the reference electrode and adopts a double salt bridge, that is, a variable diameter sleeve with a porous plug is added to the original saturated mercuric sulfate electrode, the interior of which is filled with electrolyte, the original reference electrode is inserted into the variable diameter sleeve with a porous plug, and then the variable diameter sleeve with a porous plug is inserted into the reference arm, and the assembly is performed without structural modification of the original instrument, thereby overcoming the above two disadvantages of the existing reference electrode, further improving the numerical discreteness, and further improving the accuracy.

[0022] The method of the present invention adds a check valve in the tube diameter of the electrolytic cell at the interface between the electrolytic cell and the cracking tube, which can effectively prevent the electrode liquid in the electrolytic cell from instantly flowing back into the cracking tube when oxygen and nitrogen are suddenly stopped, thereby causing damage to the cracking tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a double salt bridge of the electrolytic cell of Example 7 of the present invention;

[0024] Figure 2 This is a schematic diagram of a cell body check valve of an electrolytic cell according to Example 7 of the present invention;

[0025] Figure 3 The results of the test on the inhibition of sulfur by using dimethyl disulfide as the base liquid electrode dynamic protective agent;

[0026] Figure 4 This is the result of the detection of the inhibition of sulfur by the electrode dynamic protective agent when the sulfur standard substance is used as the interfering sulfur element.

[0027] The accompanying drawings are marked as follows:

[0028] Reference electrode 1, reference electrode gasket 2, reference electrode salt bridge 2-1, reducer with porous plug sleeve 3, reducer with porous plug sleeve salt bridge 3-1, reference arm inlet 4, reference arm and cell body support 5, reference arm 6, reference arm and electrolytic cell connection 7, electrolytic cell base 8, electrolytic cell body 9, electrolytic cell top air outlet 9-1, electrolytic cell body bayonet 9-2, measuring electrode 10, electrode body 11, anti-electrode body rotation interface 11-1, anti-electrode body rotation knob 11-2, electrolytic cathode 12, electrolytic cathode platinum wire 12-1, check valve 13, electrolytic cell body and air inlet pipe diameter support 14, air inlet pipe diameter port 15. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0031] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0032] Example 1

[0033] An electrode dynamic modification protective agent is composed of the following components and their weight parts:

[0034] 20 parts of benzotriazole, 30 parts of 5-methyl-1H-benzotriazole, 20 parts of 4-methyl-1H-benzotriazole, 10 parts of 5-ethyl-1H-benzotriazole, 10 parts of 4-ethyl-1H-benzotriazole, 5 parts of 5-propyl-1H-benzotriazole, and 8 parts of 4-propyl-1H-benzotriazole.

[0035] Example 2

[0036] An electrode dynamic modification protective agent is composed of the following components and their weight parts:

[0037] 10 parts of 5-methyl-1H-benzotriazole, 50 parts of 4-methyl-1H-benzotriazole, 20 parts of 5-ethyl-1H-benzotriazole, 10 parts of 5-propyl-1H-benzotriazole, and 10 parts of 4-propyl-1H-benzotriazole.

[0038] Example 3

[0039] An electrode dynamic modification protective agent is composed of the following components and their weight parts:

[0040] 30 parts of benzotriazole, 50 parts of 5-methyl-1H-benzotriazole, 20 parts of 4-ethyl-1H-benzotriazole, 10 parts of 5-propyl-1H-benzotriazole, and 10 parts of 4-propyl-1H-benzotriazole.

[0041] Example 4

[0042] An electrolyte solution is composed of the following components: 20 ml of 70% (v / v) glacial acetic acid pure water solution, 0.2 ml of 2% (w / v) electrode dynamic modification protective agent ethanol solution. The electrode dynamic modification protective agent is described in Example 1.

[0043] Example 5

[0044] An electrolyte solution is composed of the following components: 20 ml of 70% (v / v) glacial acetic acid pure water solution, 0.1 ml of 2% (w / v) ethanol solution of electrode dynamic modification protective agent. The electrode dynamic modification protective agent is described in Example 2.

[0045] Example 6

[0046] An electrolyte solution is composed of the following components: 20 ml of 70% (v / v) glacial acetic acid pure water solution and 10 ml of 2% (w / v) ethanol solution of electrode dynamic modification protective agent. The electrode dynamic modification protective agent is described in Example 3.

[0047] Example 7

[0048] A method for detecting the organic chlorine content of crude oil by microcoulometric method, the method differs from the method for testing the organic chlorine content of crude oil by coulometric instrument described in GB / T 18612-2011 in that:

[0049] The electrolyte described in Example 4 was used.

[0050] The electrolytic cell used is also provided with a variable diameter belt porous plug sleeve 3, the electrolytic cell reference electrode 1 is placed in the variable diameter belt porous plug sleeve 3, and the lower part of the variable diameter belt porous plug sleeve 3 is placed in the reference arm 6; a salt bridge 3-1 is provided at the lower end of the variable diameter belt porous plug sleeve 3, and the salt bridge 3-1 and the reference electrode salt bridge 2-1 form a double salt bridge structure. A reference electrode gasket is also provided at the upper end of the variable diameter belt porous plug sleeve 3.

[0051] A check valve 13 is arranged in the diameter 15 of the air inlet of the electrolytic cell, which can effectively prevent the electrolyte in the electrolytic cell from instantly flowing back into the cracking tube when the oxygen and nitrogen are suddenly stopped, thereby causing damage to the cracking tube.

[0052] 1. Accuracy-related tests

[0053] The method described in Example 7 was used to detect the organic chlorine content of crude oil, and the results are shown in Table 1 below.

[0054] Table 1

[0055]

[0056] The method of testing organic chlorine in crude oil by coulometric meter in GB / T 18612-2011 was used to detect organic chlorine in crude oil samples, and the electrolyte consisted of 70% (v / v) glacial acetic acid + 30% (v / v) pure water. The results are shown in Table 2 below.

[0057] Table 2

[0058]

[0059]

[0060] It can be seen from Tables 1 and 2 that the coefficient of variation of the organic chlorine content in crude oil measured by the method described in Example 7 is 3.85 on average. Compared with the existing conventional coulometric method, the coefficient of variation is reduced from 14.70 to 3.85, the discreteness of the measured values ​​is greatly reduced, and the measurement accuracy is effectively improved.

[0061] (II) Experiment on the inhibitory effect of electrode dynamic modification protective agent on sulfur element in crude oil during detection

[0062] 1. Select dimethyl disulfide as the interfering sulfur element. First, measure the chloride ion content (theoretical value is 0) in the dimethyl disulfide reagent in two electrolytes respectively. Then, gradually add chlorine standard substances to dimethyl disulfide to increase the proportion of chloride ions in the sample. Detect the influence of sulfur element on the test results as the chloride ions increase.

[0063] The first electrolyte is the electrolyte described in Example 4;

[0064] The second electrolyte is composed of 70% (v / v) glacial acetic acid + 30% (v / v) pure water.

[0065] The specific method is:

[0066] 1. Take 1.0mL of dimethyl disulfide (DMDS) and add it to a 10mL volumetric flask 1, take 6.4μL and measure its organic chlorine. (Molecular weight M=94.2, d=1.0625, Cs=7.23×105μg / mL), pay attention to observe whether there is a peak, peak shape, precipitation color and particle size.

[0067] 2. Add 1mL (10ppm) chlorine standard to bottle 1, mix well, and put the total volume into bottle 2 to measure the organic chlorine. At this time, Ccl = 5.0μg / mL, Cs = 3.62×105μg / mL, and Cs / CCl = 72,300 times.

[0068] 3. Add 1 mL of chlorine standard to the above 2 bottles, mix well, and put the total volume into bottle 3 to measure the organic chlorine. At this time, Ccl = 6.7 μg / mL, Cs = 2.41×105 μg / mL, and Cs / Ccl = 36,100 times.

[0069] 4. Add 1 mL of chlorine standard to the above 3 bottles, mix well, and place in bottle 4 to measure the organic chlorine. At this time, Ccl = 7.5 μg / mL, Cs = 1.80×10 5 μg / mL, Cs / Ccl=24,000 times.

[0070] 5. Add 1 mL of chlorine standard to the above 4 bottles, mix well, and place in bottle 5 to measure the organic chlorine. At this time, Ccl = 8.0 μg / mL, Cs = 1.4.5×10 5 μg / mL, Cs / Ccl=18,000 times.

[0071] 6. Add 5 mL of chlorine standard to the above 5 bottles, mix well, and the total volume is 10.0 mL. Place it in bottle 6 and measure the organic chlorine. At this time, Ccl = 9.0 μg / mL, Cs = 7.23×10 4 μg / mL, Cs / Ccl=8033 times.

[0072] The results are as follows Figure 1 shown.

[0073] Depend on Figure 1 It can be seen that in the detection using dimethyl disulfide as the base liquid, as Cs / Ccl gradually decreases, the influence of sulfur on chloride ions gradually decreases, while the electrode dynamic modification protective agent has a certain inhibitory effect on sulfur.

[0074] 2. Select a sulfur standard substance containing 2000 mg / L sulfur as the interfering sulfur element. First, measure the chloride ion content (theoretical value is 0) in the sulfur standard substance in two electrolytes respectively. Then, gradually add chlorine standard substances to the sulfur standard substance to increase the proportion of chloride ions in the sample. Detect the impact of sulfur element on the test results as the chloride ions increase.

[0075] Electrolyte 1: the electrolyte described in Example 4;

[0076] Electrolyte 2: 70% (v / v) glacial acetic acid + 30% (v / v) pure water.

[0077] The specific method is:

[0078] 1. Take 1 ml of sulfur standard substance, add 0.2 ml of chlorine standard substance, mix well, place in bottle 1, and measure organic chlorine.

[0079] 2. Take the mixture in bottle 1, add 22.2 ml of chlorine standard substance and mix thoroughly, then place in bottle 2 to measure organic chlorine.

[0080] 3. Take the mixture in bottle 2, add 27.8 ml of chlorine standard substance and mix thoroughly, then place in bottle 3 to measure organic chlorine.

[0081] 4. Take the mixture in bottle 3, add 35.7 ml of chlorine standard substance and mix thoroughly, then place in bottle 4 to measure organic chlorine.

[0082] 5. Take the mixture in bottle 4, add 47.6 ml of chlorine standard substance and mix thoroughly, then place in bottle 5 to measure organic chlorine.

[0083] 6. Take the mixture in bottle 5, add 66.7 ml of chlorine standard substance and mix thoroughly, then place in bottle 6 to measure organic chlorine.

[0084] 7. Take the mixture in bottle 6, add 0.1 ml of chlorine standard substance and mix thoroughly, then place in bottle 7 to measure organic chlorine.

[0085] 8. Take the mixture in bottle 7, add 0.17 ml of chlorine standard substance and mix thoroughly, then place in bottle 8 to measure organic chlorine.

[0086] 9. Take the mixture in bottle 8, add 0.33 ml of chlorine standard substance and mix thoroughly, then place in bottle 9 to measure organic chlorine.

[0087] 10. Take the mixture in bottle 9, add 1 ml of chlorine standard substance and mix thoroughly, then place in bottle 10 to measure organic chlorine.

[0088] 11. Take the mixture in bottle 10, add 1 ml of chlorine standard substance and mix thoroughly, then place in bottle 11 to measure organic chlorine.

[0089] The results are as follows Figure 2 shown.

[0090] Depend on Figure 2 It can be seen that in the detection of sulfur standard substances as base liquid, as Cs / Ccl gradually decreases, the influence of sulfur on chloride ions gradually decreases, while the electrode dynamic modification protective agent has a certain inhibitory effect on sulfur.

[0091] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An electrode dynamic modification protective agent, characterized in that: The invention is composed of the following components and their weight parts: 0-30 parts of benzotriazole and 10-200 parts of benzotriazole derivative; The aromatic ring of the benzotriazole derivative carries an alkyl substituent, and the substitution position is at the 4th or 5th position.

2. The electrode dynamic modification protective agent according to claim 1, characterized in that: The substituent is a straight chain alkyl substituent.

3. The electrode dynamic modification protective agent according to claim 1, characterized in that: The benzotriazole derivative is one or more of 5-methyl-1H-benzotriazole, 4-methyl-1H-benzotriazole, 5-ethyl-1H-benzotriazole, 4-ethyl-1H-benzotriazole, 5-propyl-1H-benzotriazole, and 4-propyl-1H-benzotriazole.

4. The electrode dynamic modification protective agent according to claim 1, characterized in that: The benzotriazole derivative is composed of the following components and their weight parts:

5. 10-50 parts of 5-methyl-1H-benzotriazole, 0-50 parts of 4-methyl-1H-benzotriazole, 0-20 parts of 5-ethyl-1H-benzotriazole, 0-20 parts of 4-ethyl-1H-benzotriazole, 0-10 parts of 5-propyl-1H-benzotriazole, and 0-10 parts of 4-propyl-1H-benzotriazole.

5. An electrolyte, characterized in that: The electrolyte is composed of the following components: an ethanol solution of the electrode dynamic modification protective agent according to any one of claims 1 to 5 and a glacial acetic acid aqueous solution; The concentration of the electrode dynamic modification protective agent ethanol solution is 1% (w / v)-5% (w / v).

6. The electrolyte according to claim 5, characterized in that: The volume ratio of the ethanol solution of the electrode dynamic modification protective agent to the glacial acetic acid aqueous solution is 0.001-0.

5.

7. Use of the electrode dynamic modification protective agent according to any one of claims 1 to 4 or the electrolyte according to claims 5 to 6 in detecting the organic chlorine content of crude oil.

8. A method for detecting the organic chlorine content of crude oil by microcoulometric method, characterized in that: The electrolytic cell used adopts the electrolyte described in claim 5 or 6.

9. The method according to claim 8, characterized in that: The electrolytic cell is also provided with a variable diameter belt porous plug sleeve, the electrolytic cell reference electrode is placed in the variable diameter belt porous plug sleeve, and the lower part of the variable diameter belt porous plug sleeve is placed in the reference arm; a salt bridge is provided at the lower end of the variable diameter belt porous plug sleeve, and the salt bridge and the reference electrode salt bridge form a double salt bridge structure.

10. The method according to claim 8, characterized in that: A check valve is arranged inside the diameter of the air inlet pipe of the electrolytic cell.

Images