High-temperature corrosion inhibitor for macromolecular sulfur-phosphorus composite crude oil distillation device as well as preparation method and application of high-temperature corrosion inhibitor

Abstract

The invention provides a macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for a crude oil distillation device and a preparation method and application of the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for the crude oil distillation device, and the preparation method of the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for the crude oil distillation device comprises the following steps: step 1, dropwise adding ethylenediamine into a mixture of phenylphosphonic dichloride and acetonitrile at room temperature, and reacting for 2-4 hours; step 2, adding thiourea, heating to 100-120 DEG C, and reacting for 1-2 hours; and step 3, adding fatty acid, heating to 120-140 DEG C, and reacting for 2-4 hours to obtain the macromolecular sulfur-phosphorus composite crude oil distillation device high-temperature corrosion inhibitor. The macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for the crude oil distillation device is low in phosphorus content, contains a sulfur element, has the characteristics of small addition amount, high corrosion inhibition rate, low cost and easiness in production, and has a good application prospect and large-scale industrial popularization potential in the field of crude oil distillation devices.

Description

Technical Field

[0001] The invention relates to corrosion inhibitor technology, and in particular to a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit, and a preparation method and application thereof. Background Art

[0002] In the process of oil refining, it is inevitable to encounter high-temperature cyclopentane acid and sulfur corrosion problems. High-temperature corrosion is one of the main technical difficulties encountered in the process of crude oil refining for a long time. With the increase of the acid value of crude oil refining raw materials in recent years, the problem of high-temperature corrosion has become more and more serious. Especially marine cyclopentane crude oil, which has the characteristics of high density, high acid value and high salt content. The corrosion of the atmospheric and vacuum unit is divided into low-temperature zone corrosion (below 120℃) and high-temperature zone corrosion (240~480℃). The high-temperature zone corrosion is mainly cyclopentane acid corrosion and high-temperature sulfur corrosion. High-temperature corrosion often leads to corrosion damage of oil refining equipment systems and pipelines. The corrosion sites are mainly at the outlet of the atmospheric and vacuum furnace, the atmospheric and vacuum oil conversion line, the wall of the atmospheric and vacuum tower feed section and the vacuum three-line. These corrosion sites mainly show the characteristics of high flow rate, easy to form vortex and large scouring force. These corrosions seriously affect the safe production of the refinery and the long-term operation of the device.

[0003] In order to reduce the impact of cyclohexane acid corrosion on equipment, refineries can take the following measures: crude oil deacidification treatment, equipment using cyclohexane acid corrosion resistant materials, and adding high-temperature corrosion inhibitors. Since adding corrosion inhibitors has the characteristics of low cost and good effect, refineries generally adopt the method of adding high-temperature corrosion inhibitors to reduce the corrosion of cyclohexane acid in high-temperature parts. The high-temperature corrosion inhibitors used at home and abroad are mainly divided into two types: phosphorus and non-phosphorus. Phosphorus corrosion inhibitors are mainly organic compounds containing phosphoric acid or phosphite. Phosphorus corrosion inhibitors can generate oil-insoluble substances with metallic iron, forming a layer of chemical protective film on the metal surface to isolate the metal from contact with corrosive substances such as cyclohexane acid. The polar molecules or atoms in the non-phosphorus high-temperature corrosion inhibitor form a physical adsorption film with iron and adsorb on the metal surface, thereby achieving the purpose of isolating cyclohexane acid from protecting the metal. In terms of corrosion inhibition effect, phosphorus corrosion inhibitors are significantly better than non-phosphorus corrosion inhibitors due to the formation of chemical adsorption films. Physical adsorption film. However, currently, most high-temperature corrosion inhibitors are phosphorus-based. Phosphorus-based high-temperature corrosion inhibitors have the advantages of low dosage and high corrosion inhibition rate. However, because they contain harmful phosphorus elements, high-temperature decomposition can easily lead to problems such as catalyst poisoning, environmental protection and corrosion in the subsequent processes of refineries. At present, various petrochemical units such as Sinopec and PetroChina have begun to restrict the use of phosphorus-based high-temperature corrosion inhibitors. Non-phosphorus-based ones do not contain harmful elements, but generally have the disadvantages of large dosage and poor corrosion inhibition effect. Therefore, it has become a top priority to develop a composite high-temperature corrosion inhibitor with low phosphorus, high efficiency and synergistic synergy. Summary of the invention

[0004] The purpose of the present invention is to solve the problems that phosphorus-containing corrosion inhibitors on the market have high phosphorus content and are easy to cause poisoning of downstream processing catalysts, and phosphorus-free high-temperature corrosion inhibitors have large addition amounts and poor corrosion inhibition effects. A macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation units is proposed. The inhibitor has low phosphorus content, contains sulfur, has small addition amounts, high corrosion inhibition rates, low costs, and is easy to produce. It has good application prospects and large-scale industrial promotion potential in the field of crude oil distillation units.

[0005] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit, the molecular formula of which is shown in Formula I, wherein n is a natural number between 0 and 8:

[0007]

[0008] Furthermore, the molecular formula of the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit is as shown in Formula II:

[0009]

[0010] Another object of the present invention is to disclose a method for preparing a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit, comprising the following steps:

[0011] Step 1, adding ethyleneamine dropwise to a mixture of phenylphosphonyl dichloride and acetonitrile at room temperature, and reacting for 2-4 hours;

[0012] Step 2, add thiourea, raise the temperature to 100-120°C and react for 1-2 hours;

[0013] Step 3: Add fatty acid, raise the temperature to 120-140° C., and react for 2-4 hours to prepare a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit.

[0014] Furthermore, the molar ratio of phenylphosphonyl dichloride, acetonitrile, ethyleneamine, thiourea and fatty acid is 1-1.2: 4-8: 2-3: 2-3: 2-3. Preferably, the molar ratio of phenylphosphonyl dichloride, acetonitrile, ethyleneamine, thiourea and oleic acid is 1: 5: 2.2: 2: 2.

[0015] Furthermore, in step 2, acetonitrile is evaporated and condensed for recovery. The boiling point of acetonitrile is 81.5°C, and the reaction temperature in step 2 is 100-120°C. During the reaction, acetonitrile is evaporated and condensed for recovery and can be reused.

[0016] Furthermore, the ethyleneamine is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethylenepolyamine.

[0017] Furthermore, the fatty acid is one or more of oleic acid, linoleic acid, tall oil acid, stearic acid, coconut acid, palmitic acid and linolenic acid.

[0018] Furthermore, the reaction time in step 1 is 3 hours.

[0019] Furthermore, the reaction time of heating to 100° C. in step 2 is 1.5 hours.

[0020] Furthermore, the reaction time of heating to 140° C. in step 3 is 3 hours.

[0021] Taking the preparation of formula II macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit as an example, its synthesis route is as follows:

[0022]

[0023]

[0024] Another object of the present invention is to disclose the use of a macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for a crude oil distillation unit in the field of high-temperature corrosion inhibition.

[0025] Furthermore, the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation units is particularly suitable for corrosion inhibition of crude oil distillation units.

[0026] Furthermore, the macromolecular sulfur-phosphorus composite crude oil distillation unit high-temperature corrosion inhibitor is particularly suitable for the heating furnace tubes, atmospheric tower diesel distillation pipelines, vacuum tower side lines, atmospheric towers and vacuum tower bottoms of the atmospheric and vacuum units of the refinery processing high-acid value crude oil, and is suitable for chemical corrosion caused by petroleum acid in the temperature range of 200-400°C.

[0027] Furthermore, the application temperature of the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit is 200-400°C.

[0028] Furthermore, the application method of the high temperature corrosion inhibitor of the macromolecular sulfur-phosphorus composite crude oil distillation unit is: the diluted corrosion inhibitor is continuously injected into the fluid before the corrosion part by a gear metering pump. The solvent used for dilution is one or more of diesel, solvent oil and kerosene. The volume ratio of the high temperature corrosion inhibitor of the macromolecular sulfur-phosphorus composite crude oil distillation unit to the solvent is 1:20-50.

[0029] Furthermore, the application amount of the macromolecular sulfur-phosphorus composite crude oil distillation unit high-temperature corrosion inhibitor is 80-100 μg / g, which can control the iron ion content of the fluid in the pipeline to be less than 3 μg / g.

[0030] The macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit of the present invention, its preparation method and use have the following advantages compared with the prior art:

[0031] 1) The high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit of the present invention has a low phosphorus content (the phosphorus content of the traditional corrosion inhibitor is 10%-18%, while the phosphorus content of the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit of the present invention is only 2%-3%), contains sulfur element, has low cost, and is easy to produce.

[0032] 2) The laboratory addition amount of the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit of the present invention is 150 μg / g, and the corrosion inhibition rate is higher than 90%. The addition amount in industrial application is 80-100 μg / g, and the iron ion is less than 3 μg / g.

[0033] 3) The macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation units of the present invention has good application prospects and large-scale industrial promotion potential in the field of crude oil distillation units. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the infrared spectrum of the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit in Example 1. DETAILED DESCRIPTION

[0035] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0036] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0037] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0038] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0039] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0040] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0041] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0042] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0043] In this manual, unless otherwise specified, % refers to mass percentage.

[0044] Example 1

[0045] This embodiment discloses a macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit, and its molecular formula is as follows:

[0046]

[0047] The method for preparing the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit comprises the following steps:

[0048] Add 1 mol of phenylphosphonic acid dichloride and 5 mol of acetonitrile to the container, add 2.5 mol of diethylenetriamine dropwise at room temperature, and react for 3 hours at room temperature. Add 2.5 mol of thiourea, raise the temperature to 100°C and continue to react for 1.5 hours. It is necessary to condense and recover acetonitrile. After the reaction, add 2.5 mol of oleic acid and react at 140°C for 3 hours to obtain the finished product: a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit.

[0049] Figure 1 This is the infrared spectrum of the high-temperature corrosion inhibitor of the macromolecular sulfur-phosphorus composite crude oil distillation unit in Example 1. The visible wavelength is 2900 cm -1 The peak at 1600 cm-1 is the stretching vibration peak of methyl methylene. -1 The carbonyl vibration peak is at 1200cm -1 The carbon nitrogen amide vibration peak is at 1086 cm -1 The absorption peak of phosphorus oxygen double bond is 1050cm -1 The carbon-sulfur double bond vibration peak is at 1042 cm -1 The sharp peak is the vibration peak of nitrogen and phosphorus single bonds, which shows that the synthesized product is the target product.

[0050] The corrosion inhibition evaluation of the high temperature corrosion inhibitor of the macromolecular sulfur-phosphorus composite crude oil distillation unit in this example is as follows:

[0051] 1500mL of white oil corrosion medium with acid value adjusted to 7mgKOH / g was placed in an autoclave. A 20# carbon steel test piece with specification III type A3 was cleaned and weighed, and then hung in the autoclave so that the test piece was completely immersed in the experimental medium. At a certain stirring speed (200rad / min), it was heated to 280℃ and maintained for 6 hours (without nitrogen protection), and the weight change of the test piece before and after the blank experiment and the addition experiment was investigated. The corrosion inhibition rate of the corrosion inhibitor was calculated by the weight change of the test piece. The results are expressed as mass percentage, and it can be seen that the corrosion inhibition rate exceeds 90% when the amount of corrosion inhibitor added exceeds 150μg / g.

[0052] Table 1 Corrosion inhibition rate

[0053] Serial number Corrosion inhibitor addition amount Corrosion inhibition rate 1 50μg / g 81.2％ 2 100μg / g 87.6％ 3 150μg / g 92.3％ 4 200μg / g 93.5％

[0054] Example 2

[0055] This embodiment discloses a macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit, and its molecular formula is as follows:

[0056]

[0057] The method for preparing the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit comprises the following steps:

[0058] Add 1 mol of phenylphosphonic acid dichloride and 6 mol of acetonitrile to the container, add 3 mol of triethylenetetramine dropwise at room temperature, and react at room temperature for 4 hours. Add 3 mol of thiourea, raise the temperature to 100°C and continue to react for 2 hours. It is necessary to condense and recover acetonitrile. After the reaction, add 3 mol of linoleic acid and react at 140°C for 4 hours to obtain the finished product: a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit. The target product was prepared by infrared spectrum analysis.

[0059] The corrosion inhibition evaluation of the high temperature corrosion inhibitor of the macromolecular sulfur-phosphorus composite crude oil distillation unit in this example is as follows:

[0060] 1500mL of white oil corrosion medium with acid value adjusted to 7mgKOH / g was placed in an autoclave. A 20# carbon steel test piece with specification III type A3 was cleaned and weighed, and then hung in the autoclave so that the test piece was completely immersed in the experimental medium. At a certain stirring speed (200rad / min), it was heated to 280℃ and maintained for 6 hours (without nitrogen protection), and the weight change of the test piece before and after the blank experiment and the addition experiment was investigated. The corrosion inhibition rate of the corrosion inhibitor was calculated by the weight change of the test piece. The results are expressed as mass percentage, and it can be seen that the corrosion inhibition rate exceeds 90% when the amount of corrosion inhibitor added exceeds 150μg / g.

[0061] Table 2 Corrosion inhibition rate

[0062] Serial number Corrosion inhibitor addition amount Corrosion inhibition rate 1 50μg / g 80.3％ 2 100μg / g 86.4％ 3 150μg / g 91.8％ 4 200μg / g 92.4％

[0063] Example 3

[0064] This embodiment discloses a macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit, and its molecular formula is as follows:

[0065]

[0066] The method for preparing the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit comprises the following steps:

[0067] Add 1.2 mol of phenylphosphonic acid dichloride and 6 mol of acetonitrile to the container, add 3 mol of tetraethylenepentamine dropwise at room temperature, and react at room temperature for 4 hours. Add 3 mol of thiourea, raise the temperature to 100°C and continue to react for 2 hours. It is necessary to condense and recover acetonitrile. After the reaction, add 2 mol of tall oil acid and react at 140°C for 4 hours to obtain the finished product: a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit. The target product was prepared by infrared spectrum analysis.

[0068] The corrosion inhibition evaluation of the high temperature corrosion inhibitor of the macromolecular sulfur-phosphorus composite crude oil distillation unit in this example is as follows:

[0069] 1500mL of white oil corrosion medium with acid value adjusted to 7mgKOH / g was placed in an autoclave. A 20# carbon steel test piece with specification III type A3 was cleaned and weighed, and then hung in the autoclave so that the test piece was completely immersed in the experimental medium. At a certain stirring speed (200rad / min), it was heated to 280℃ and maintained for 6 hours (without nitrogen protection), and the weight change of the test piece before and after the blank experiment and the addition experiment was investigated. The corrosion inhibition rate of the corrosion inhibitor was calculated by the weight change of the test piece. The results are expressed as mass percentage, and it can be seen that the corrosion inhibition rate exceeds 90% when the amount of corrosion inhibitor added exceeds 150μg / g.

[0070] Table 2 Corrosion inhibition rate

[0071] Serial number Corrosion inhibitor addition amount Corrosion inhibition rate 1 50μg / g 78.6％ 2 100μg / g 85.3％ 3 150μg / g 90.2％ 4 200μg / g 91.9％

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit, characterized in that: The molecular formula is shown in Formula I, where n is a natural number between 0 and 8:

2. The high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit according to claim 1, characterized in that: Its molecular formula is shown in Formula II:

3. A method for preparing the macromolecular sulfur-phosphorus composite high-temperature corrosion inhibitor for crude oil distillation unit according to claim 1 or 2, characterized in that: The following steps are involved: Step 1, adding ethyleneamine dropwise to a mixture of phenylphosphonic dichloride and acetonitrile at room temperature, and reacting for 2-4 hours; Step 2, add thiourea, raise the temperature to 100-120°C and react for 1-2 hours; Step 3: Add fatty acid, raise the temperature to 120-140° C., and react for 2-4 hours to prepare a high-temperature corrosion inhibitor for a macromolecular sulfur-phosphorus composite crude oil distillation unit.

4. The method for preparing the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit according to claim 3, characterized in that: The molar ratio of phenylphosphonyl dichloride, acetonitrile, ethyleneamine, thiourea and fatty acid is 1-1.2:4-8:2-3:2-3:2-3.

5. The method for preparing the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit according to claim 3, characterized in that: In step 2, acetonitrile is evaporated and recovered by condensation.

6. The method for preparing the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit according to claim 3, characterized in that: The ethyleneamine is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethylenepolyamine.

7. The method for preparing the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit according to claim 3, characterized in that: The fatty acid is one or more of oleic acid, linoleic acid, tall oil acid, stearic acid, coconut acid, palmitic acid and linolenic acid.

8. The method for preparing the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit according to claim 3, characterized in that: The reaction time in step 1 is 3 hours; And / or, the reaction time of heating to 100° C. in step 2 is 1.5 hours; And / or, the reaction time of heating to 140° C. in step 3 is 3 hours.

9. Use of the macromolecular sulfur-phosphorus composite crude oil distillation unit high-temperature corrosion inhibitor according to claim 1 or 2 in the field of high-temperature corrosion inhibition.

10. The use according to claim 9, characterized in that: The application temperature of the macromolecular sulfur-phosphorus composite crude oil distillation unit high-temperature corrosion inhibitor is 200-400°C; And / or, the method for applying the high-temperature corrosion inhibitor for the macromolecular sulfur-phosphorus composite crude oil distillation unit is: continuously injecting the diluted corrosion inhibitor into the fluid before the corrosion site using a gear metering pump; And / or, the application amount of the macromolecular sulfur-phosphorus composite crude oil distillation unit high-temperature corrosion inhibitor is 80-100 μg / g.

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