Corrosion inhibitor for petroleum refining distillation device and preparation method thereof

Abstract

The invention discloses a corrosion inhibitor for a petroleum refining distillation device and a preparation method thereof, and relates to the technical field of petrochemical industry. The corrosion inhibitor for the petroleum refining distillation device comprises the following raw materials in parts by weight: 30-35 parts of a corrosion inhibitor main agent, 4-5 parts of a synergist, 8-12 parts of an emulsifier, 2-3 parts of propargyl alcohol, 6-10 parts of triethanolamine and 120 parts of deionized water. According to the novel benzimidazole corrosion inhibitor prepared by the invention, a surface active group with directional adsorption capacity on a metal surface is introduced into a molecular structure through copolymerization, so that the corrosion inhibitor can form a protective film on the metal surface more easily, and the corrosion inhibition efficiency of the novel benzimidazole corrosion inhibitor is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, and in particular to a corrosion inhibitor for a petroleum refining and distillation device and a preparation method thereof. Background Art

[0002] Atmospheric and vacuum distillation is a process in the crude oil refining process and is the foundation of the entire oil refining process. HCl and H2S corrosion in the overhead system of the atmospheric and vacuum distillation unit has long been a major problem for refineries both domestically and internationally. Analysis of the physical properties of the distillation tower overhead indicates that the water in the overhead oil-water mixture is relatively low in acidity, even reaching a pH of 1-1.3, potentially posing a risk of severe liquid acidic water corrosion. HCl levels are particularly high at the dew point, with reports suggesting HCl concentrations in liquid water can reach 1-3% by weight at the dew point. This acidic environment can rapidly cause dew point corrosion of carbon steel.

[0003] To combat acid corrosion, corrosion inhibitors are often added to the acidification system. Benzimidazole and its derivatives contain heteroatoms such as nitrogen, sulfur, and oxygen, which provide complexing and coordination functions and are widely used in metal corrosion protection. Given that the corrosion inhibition performance of these inhibitors primarily depends on the adsorption of the molecules on the metal surface, which is closely related to the molecular structure, appropriate chemical modification of these substances can be used to enhance their adsorption properties and thus improve their corrosion inhibition effectiveness.

[0004] Chinese invention patent publication number CN111621791A discloses a refinery distillation tower overhead corrosion inhibitor resistant to dilute hydrochloric acid and hydrogen sulfide corrosion. The inhibitor comprises N-alkylpyridinium tetrafluoroborate or N-alkylpyridinium hexafluorophosphate, and NaBr. While the inhibitor boasts low cost, good water solubility, and environmental friendliness, its corrosion protection is limited. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a corrosion inhibitor for a petroleum refining distillation unit and a preparation method thereof.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A corrosion inhibitor for a petroleum refining distillation unit, comprising the following raw materials in parts by weight:

[0008] Corrosion inhibitor main agent: 30-35 parts,

[0009] Synergist: 4-5 parts,

[0010] Emulsifier: 8-12 parts,

[0011] Propynol: 2-3 parts,

[0012] Triethanolamine: 6-10 parts,

[0013] Deionized water: 120 parts;

[0014] The corrosion inhibitor main agent is prepared by the following method:

[0015] S1: Cyanuric chloride, 1H-benzo[D]imidazol-7-amine, and anhydrous Na2CO3 were added to a reaction vessel in sequence, stirred and mixed, and reacted at 0-5°C for 3-5 hours. 1H-benzo[D]imidazol-7-amine was then added, and the temperature was raised to room temperature and reacted for 44-48 hours to obtain the substituent 1. The reaction equation is shown below:

[0016]

[0017] S2: Substituted product 1, 1-amino-10-undecene, and anhydrous Na2CO3 were added to a reaction vessel in sequence, stirred and mixed, and heated to 90-95°C for 12-18 hours to obtain substituent 2. The reaction equation is shown below:

[0018]

[0019] S3: Tetrahydrofuran, substituent 2, (3-acrylamidopropyl)trimethylammonium chloride, and azobisisobutyronitrile are added to the reaction vessel in sequence, stirred and mixed, heated to 60-80°C, and reacted for 14-18 hours to obtain the main agent of the copolymer corrosion inhibitor. The reaction equation is as follows:

[0020]

[0021] The number average molecular weight of the main corrosion inhibitor is 10,000-22,000.

[0022] The mass ratio of the cyanuric chloride, the first added 1H-benzo[D]imidazol-7-amine, the second added 1H-benzo[D]imidazol-7-amine, and anhydrous Na2CO3 is 19:(10-16):(10-16):(20-24).

[0023] The mass ratio of the substituent 1, 1-amino-10-undecene and anhydrous Na2CO3 is 38:(18-22):(10-12).

[0024] The mass ratio of tetrahydrofuran, substituent 2, (3-acrylamidopropyl)trimethylammonium chloride and azobisisobutyronitrile is 100:(22-28):(8-12):(0.14-0.18).

[0025] The synergist is one of potassium iodide, antimony trioxide and antimony trichloride.

[0026] The emulsifier is one of sodium dodecylsulfonate and sodium dodecylbenzenesulfonate.

[0027] A method for preparing a corrosion inhibitor for a petroleum refining distillation unit comprises the following steps:

[0028] (1) Weigh the following by weight: corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, triethanolamine, and deionized water;

[0029] (2) Deionized water, corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, and triethanolamine are added to the reactor in sequence, stirred evenly, heated to 50-60° C., and kept warm for 1-2 hours to obtain a corrosion inhibitor for a petroleum refining distillation unit.

[0030] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0031] (1) The present invention prepares a substituent 1 by reacting cyanuric chloride with 1H-benzo[D]imidazole-7-amine; then, the substituent 1 reacts with 1-amino-10-undecene to prepare a substituent 2; finally, the substituent 2 reacts with (3-acrylamidopropyl)trimethylammonium chloride to obtain a copolymer corrosion inhibitor main agent for a petroleum refining distillation unit.

[0032] (2) The main corrosion inhibitor used in the raw material of the corrosion inhibitor for the petroleum refining distillation unit of the present invention is a polymer-type benzimidazole corrosion inhibitor. Compared with traditional low-molecular corrosion inhibitors, the number of imidazole groups in its molecular structure is increased, which improves the complexing and coordination ability of the corrosion inhibitor, making it easier to form a multi-layer dense protective film on the metal surface, thereby achieving efficient and long-lasting corrosion inhibition. At the same time, the main corrosion inhibitor contains a surfactant group (3-acrylamidopropyl) trimethylammonium chloride introduced by copolymerization. The surfactant group can be directionally adsorbed on the metal surface to form a molecular film, thereby hindering the corrosion of the metal by the acidic medium. The combination of the benzimidazole corrosion inhibitor and the surfactant group improves the corrosion inhibition performance of the corrosion inhibitor, and the corrosion inhibitor has excellent corrosion resistance when applied to the petroleum refining distillation unit. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0034] Example 1 Preparation of corrosion inhibitor main agent:

[0035] S1: Add 19g of cyanuric chloride to 130g of toluene, stir and mix at 0-5℃, slowly add 290g of 1H-benzo[D]imidazol-7-amine toluene solution (10g of 1H-benzo[D]imidazol-7-amine dissolved in 280g of toluene) dropwise, and drip completely over 10min; then slowly add 320g of Na2CO3 solution (20g of anhydrous Na2CO3 dissolved in 300g of deionized water) dropwise, and drip completely over 10min, and react for 3h; then slowly add 2 90 g of a toluene solution of 1H-benzo[D]imidazol-7-amine (10 g of 1H-benzo[D]imidazol-7-amine dissolved in 280 g of toluene) was added dropwise over 10 min, and the mixture was allowed to react at room temperature for 44 h. After the reaction, deionized water and ethyl acetate were added and extracted three times (500 mL of deionized water and 300 mL of ethyl acetate were used each time). The mixture was then dried over 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 50°C for 3 h, and dried under vacuum at 50°C for 5 h to obtain the substituent 1.

[0036] S2: Add 38g of the substituent 1 to 300g of toluene and stir to mix. Slowly add 118g of a toluene solution of 1-amino-10-undecene (18g of 1-amino-10-undecene dissolved in 100g of toluene) dropwise at 90-95°C for 5 minutes. Then slowly add 110g of a Na2CO3 solution (10g of anhydrous Na2CO3 dissolved in 100g of deionized water) dropwise for 5 minutes. After reacting for 12 hours, filter to remove insoluble matter from the system, transfer the filtrate to a separatory funnel, and allow to stand for stratification. After removing the aqueous layer, wash the toluene solution with 70g of dilute hydrochloric acid (10wt%), then thoroughly wash with 300g of a saturated Na2CO3 solution, and then wash with 500g of deionized water until neutral. Dry the washed toluene layer with 200g of anhydrous sodium sulfate for 2 hours, remove the solvent by vacuum distillation at 60°C for 1 hour, and vacuum dry at 50°C for 5 hours to obtain the substituent 2.

[0037] S3: Under nitrogen protection, 100g of tetrahydrofuran, 22g of substituent 2, 8g of (3-acrylamidopropyl)trimethylammonium chloride and 0.14g of azobisisobutyronitrile were added to the reactor in sequence, stirred and mixed, heated to 60°C, and reacted for 18h. After the reaction was completed, the mixture was distilled under reduced pressure at 65°C for 2h to remove the solvent, 100g of methanol was added, filtered, washed with 50g of methanol, and vacuum dried at 80°C for 5h to obtain a copolymer corrosion inhibitor with a number average molecular weight of 10540.

[0038] Example 2 Preparation of corrosion inhibitor main agent:

[0039] S1: Add 19g of cyanuric chloride to 130g of toluene, stir and mix at 0-5°C, slowly add 293g of 1H-benzo[D]imidazol-7-amine toluene solution (13g 1H-benzo[D]imidazol-7-amine dissolved in 280g of toluene) dropwise, and let it drip for 15 minutes; then slowly add 323g of Na2CO3 solution (23g of anhydrous Na2CO3 dissolved in 300g of deionized water) dropwise, and let it drip for 15 minutes, and let it react for 4 hours; then slowly add 29 A toluene solution of 3 g 1H-benzo[D]imidazol-7-amine (13 g 1H-benzo[D]imidazol-7-amine dissolved in 280 g toluene) was added dropwise over 10 min, and the mixture was allowed to react at room temperature for 46 h. After the reaction, deionized water and ethyl acetate were added and extracted three times (500 mL deionized water and 300 mL ethyl acetate were used each time). The mixture was then dried over 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 55°C for 2.5 h, and dried under vacuum at 60°C for 4 h to obtain the substituent 1.

[0040] S2: 38 g of the substituent 1 was added to 300 g of toluene and stirred to mix; 120 g of a toluene solution of 1-amino-10-undecene (20 g of 1-amino-10-undecene dissolved in 100 g of toluene) was slowly added dropwise at 90-95° C. for 8 minutes; 111 g of a Na2CO3 solution (11 g of anhydrous Na2CO3 dissolved in 100 g of deionized water) was then slowly added dropwise for 8 minutes; after reacting for 16 hours, the insoluble matter in the system was removed by filtration, the filtrate was transferred to a separatory funnel, and the filtrate was allowed to stand for stratification. After removing the water layer, the toluene solution was washed with 80 g of dilute hydrochloric acid (10 wt %), then with 300 g of a saturated Na2CO3 solution, and then with 500 g of deionized water until neutral. The washed toluene layer was dried over 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 60° C. for 1.5 h to remove the solvent, and dried under vacuum at 60° C. for 4 h to obtain the substituent 2, the H NMR spectrum of which is as follows: 1 H NMR (300MHz, DMSO-d6) δ10.90(d,J=6.3Hz,2H),10.08(s,2H),8.31(d,J=6.3Hz,2H),7.75(dd,J=6.1,3.1Hz,2H),7.61–7.33(m,4H),6.52(t,J=4.6Hz ,1H),5.91–5.69(m,1H),5.29–4.81(m,2H),3.50(td,J=7.2,4.6Hz,2H),2. 03(tdt,J=8.1,6.8,1.4Hz,2H),1.71(p,J=7.3Hz,2H),1.47–1.02(m,12H).

[0041] S3: Under nitrogen protection, 100 g of tetrahydrofuran, 25 g of substituent 2, 10 g of (3-acrylamidopropyl)trimethylammonium chloride, and 0.16 g of azobisisobutyronitrile were added to the reactor in sequence, stirred and mixed, heated to 70°C, and reacted for 16 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 65°C for 2.5 hours to remove the solvent, 100 g of methanol was added, filtered, washed with 50 g of methanol, and vacuum dried at 80°C for 4 hours to obtain a copolymer corrosion inhibitor with a number average molecular weight of 16460.

[0042] Example 3 Preparation of corrosion inhibitor main agent:

[0043] S1: Add 19g of cyanuric chloride to 130g of toluene, stir and mix at 0-5℃, slowly add 296g of 1H-benzo[D]imidazol-7-amine toluene solution (16g of 1H-benzo[D]imidazol-7-amine dissolved in 280g of toluene) dropwise, and finish dripping within 20min; then slowly add 324g of Na2CO3 solution (24g of anhydrous Na2CO3 dissolved in 300g of deionized water) dropwise, and finish dripping within 20min, and react for 5h; then slowly add 2 A toluene solution of 96 g 1H-benzo[D]imidazol-7-amine (16 g 1H-benzo[D]imidazol-7-amine dissolved in 280 g toluene) was added dropwise over 20 minutes, and the mixture was allowed to react at room temperature for 48 hours. After the reaction, deionized water and ethyl acetate were added and extracted three times (500 mL deionized water and 300 mL ethyl acetate were used each time). The mixture was then dried over 200 g of anhydrous sodium sulfate for 2 hours, distilled under reduced pressure at 60°C for 2 hours, and dried under vacuum at 70°C for 3 hours to obtain the substituent 1.

[0044] S2: Add 38g of the substituent 1 to 300g of toluene and stir to mix. Slowly add 122g of a toluene solution of 1-amino-10-undecene (22g of 1-amino-10-undecene dissolved in 100g of toluene) dropwise at 90-95°C for 10 minutes. Then slowly add 112g of a Na2CO3 solution (12g of anhydrous Na2CO3 dissolved in 100g of deionized water) dropwise for 10 minutes. After reacting for 18 hours, filter to remove insoluble matter from the system, transfer the filtrate to a separatory funnel, and allow to stand for stratification. After removing the aqueous layer, wash the toluene solution with 90g of dilute hydrochloric acid (10wt%), then thoroughly wash with 300g of a saturated Na2CO3 solution, and then wash with 500g of deionized water until neutral. Dry the washed toluene layer with 200g of anhydrous sodium sulfate for 2 hours, remove the solvent by vacuum distillation at 60°C for 2 hours, and vacuum dry at 70°C for 3 hours to obtain the substituent 2.

[0045] S3: Under nitrogen protection, 100 g of tetrahydrofuran, 28 g of substituent 2, 12 g of (3-acrylamidopropyl)trimethylammonium chloride, and 0.18 g of azobisisobutyronitrile were added to the reactor in sequence, stirred and mixed, heated to 80°C, and reacted for 14 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 65°C for 3 hours to remove the solvent, 100 g of methanol was added, filtered, washed with 50 g of methanol, and vacuum dried at 80°C for 3 hours to obtain a copolymer corrosion inhibitor with a number average molecular weight of 21780.

[0046] Example 4 Preparation of corrosion inhibitor for petroleum refining distillation unit:

[0047] (1) Weigh by weight 300 g of the main corrosion inhibitor (prepared in Example 1), 40 g of the synergist (potassium iodide), 80 g of the emulsifier (sodium lauryl sulfate), 20 g of propargyl alcohol, 60 g of triethanolamine, and 1200 g of deionized water;

[0048] (2) Deionized water, corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, and triethanolamine were added to the reactor in sequence, stirred evenly, heated to 50° C., and kept warm for 1 hour to obtain a corrosion inhibitor for a petroleum refining distillation unit.

[0049] Example 5 Preparation of corrosion inhibitor for petroleum refining distillation unit:

[0050] (1) Weigh by weight 330 g of the main corrosion inhibitor (prepared in Example 2), 45 g of the synergist (antimony trioxide), 100 g of the emulsifier (sodium dodecylbenzenesulfonate), 25 g of propargyl alcohol, 80 g of triethanolamine, and 1200 g of deionized water;

[0051] (2) Deionized water, corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, and triethanolamine were added to the reactor in sequence, stirred evenly, heated to 55° C., and kept warm for 1.5 hours to obtain a corrosion inhibitor for a petroleum refining distillation unit.

[0052] Example 6 Preparation of corrosion inhibitor for petroleum refining distillation unit:

[0053] (1) Weigh by weight 350 g of the main corrosion inhibitor (prepared in Example 3), 50 g of antimony trichloride (synergist), 120 g of sodium lauryl sulfate (emulsifier), 30 g of propargyl alcohol, 100 g of triethanolamine, and 1200 g of deionized water;

[0054] (2) Deionized water, corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, and triethanolamine were added to the reactor in sequence, stirred evenly, heated to 60° C., and kept warm for 2 h to obtain a corrosion inhibitor for a petroleum refining distillation unit.

[0055] Comparative Example 1

[0056] A corrosion inhibitor for a petroleum refining distillation unit has substantially the same raw materials and process as Example 5, except that the main corrosion inhibitor is replaced by an equal weight of the main corrosion inhibitor prepared by the following method.

[0057] The corrosion inhibitor main agent in this comparative example was prepared by the following method:

[0058] S3: Under nitrogen protection, 100 g of tetrahydrofuran solvent, 20 g of substituent 2 (prepared in step S2 of Example 2), 6 g of (3-acrylamidopropyl)trimethylammonium chloride, and 0.14 g of azobisisobutyronitrile were added to the reactor in sequence, stirred and mixed, heated to 60°C, and reacted for 16 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 50°C for 2 hours to remove the solvent, 100 g of methanol was added, filtered, washed with 50 g of methanol, and dried in vacuo at 50°C for 5 hours to obtain a copolymer corrosion inhibitor with a number average molecular weight of 7870.

[0059] Comparative Example 2

[0060] A corrosion inhibitor for a petroleum refining distillation unit has substantially the same raw materials and process as Example 5, except that the main corrosion inhibitor is replaced by an equal weight of the main corrosion inhibitor prepared by the following method.

[0061] The corrosion inhibitor main agent in this comparative example was prepared by the following method:

[0062] S3: Under nitrogen protection, 100 g of tetrahydrofuran solvent, 32 g of substituent 2 (prepared in step S2 of Example 2), 12 g of (3-acrylamidopropyl)trimethylammonium chloride, and 0.22 g of azobisisobutyronitrile were added to the reactor in sequence, stirred and mixed, heated to 80°C, and reacted for 18 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 50°C for 3 hours to remove the solvent, 100 g of methanol was added, filtered, washed with 50 g of methanol, and vacuum dried at 70°C for 3 hours to obtain a copolymer corrosion inhibitor with a number average molecular weight of 29740.

[0063] Comparative Example 3

[0064] A corrosion inhibitor for a petroleum refining distillation unit, whose raw material components and preparation method are basically the same as those of Example 5, except that the corrosion inhibitor main agent added to the components of step (2) is replaced by an equal weight of the substitute 2 prepared in step S2 of Example 2.

[0065] Comparative Example 4

[0066] A corrosion inhibitor for a petroleum refining distillation unit, whose raw material components and preparation method are basically the same as those in Example 5, except that the corrosion inhibitor main agent added to the components of step (2) is replaced by 235.71g of substitute 2 (prepared in Example 2) and 94.29g of (3-acrylamidopropyl)trimethylammonium chloride.

[0067] Comparative Example 5

[0068] A corrosion inhibitor for a petroleum refining distillation unit, whose raw material components and preparation method are basically the same as those of Example 5, except that the corrosion inhibitor main agent added to the components of step (2) is replaced by an equal weight of 2-p-chlorobenzylbenzimidazole.

[0069] Comparative Example 6

[0070] A corrosion inhibitor for a petroleum refining distillation unit, the raw material components of which are different from those in Example 5, the main agent of the corrosion inhibitor in this comparative example is prepared by the following method:

[0071] (1) Weigh by weight the corrosion inhibitor main agent (tribenzyl-(2-benzyl)pyridyl ammonium chloride): 200 g, synergist: 20 g (potassium iodide 10 g, antimony trichloride 5 g, antimony trichloride 5 g), dispersant: 5 g (OP-10), propargyl alcohol: 5 g, triethanolamine: 90 g, surfactant: 10 g (sodium linear alkylbenzene sulfonate), solvent: 670 g (N,N-dimethylformamide 50 g, N,N-dimethylaniline 50 g, methanol 570 g);

[0072] (2) Adding a corrosion inhibitor main agent, a synergist, a dispersant, propargyl alcohol, triethanolamine, a surfactant, and a solvent into a reactor in sequence, stirring the mixture evenly, and obtaining a corrosion inhibitor for a petroleum refining distillation unit.

[0073] Comparative Example 7

[0074] The corrosion inhibitor was prepared using the raw materials and method of Example 6 in publication number CN111621791A.

[0075] Corrosion inhibition rate determination: According to the corrosion inhibitor evaluation indicators in Q / SHCG 109-2017 "Technical Requirements for Neutralizing Corrosion Inhibitors for Crude Oil Distillation Units", the corrosion inhibition performance of the corrosion inhibitors prepared in Examples 4-6 and Comparative Examples 1-7 was tested using the static coupon weight loss method, and the corrosion inhibition rate of each group of steel sheets was recorded. The test results are shown in Table 1.

[0076] Specific test conditions and steps:

[0077] Medium composition: HCl: 1000 mg / L;

[0078] Test temperature: 85℃;

[0079] Test time: 6h;

[0080] Test material: 20# steel.

[0081] First, polish the 20# steel to a bright finish, clean it with petroleum ether, acetone and ethanol, dry it, and weigh it. Put the prepared solution into a reaction vessel with a reflux device, add 100ppm of the prepared corrosion inhibitor, stir it evenly, hang the weighed 20# steel into the reaction vessel, heat it to 85℃, stabilize it under this condition for 6h, then take out the sample, remove the corrosion product film on the surface of the sample, dry it, weigh it, and calculate the corrosion inhibition rate.

[0082] Table 1

[0083] project Corrosion inhibitor dosage (ppm) Corrosion inhibition rate (%) Example 4 100 98.27 Example 5 100 99.12 Example 6 100 97.85 Comparative Example 1 100 88.30 Comparative Example 2 100 89.42 Comparative Example 3 100 83.62 Comparative Example 4 100 84.86 Comparative Example 5 100 69.65 Comparative Example 6 100 83.12 Comparative Example 7 100 85.69

[0084] It can be seen from Table 1 that the corrosion inhibitor for the petroleum refining distillation unit prepared in the present application has a corrosion inhibition rate of more than 97% after testing, indicating that the corrosion inhibitor for the petroleum refining distillation unit prepared in the present application has good anti-corrosion effect.

[0085] Comparative Example 1 of the present application uses a corrosion inhibitor main agent with a number average molecular weight lower than 10,000. As can be seen from the data in Table 1, its corrosion inhibition rate is 88.30%.

[0086] Comparative Example 2 of the present application uses a corrosion inhibitor main agent with a number average molecular weight higher than 22,000. As can be seen from the data in Table 1, its corrosion inhibition rate is 89.42%.

[0087] Comparative Example 3 of the present application is different from Example 5. Its raw material components and preparation method are basically the same as those of Example 5. The difference is that the main corrosion inhibitor added to the components of step (2) is replaced by an equal weight of the substitute 2 prepared in step S2 of Example 2. It can be seen from the data in Table 1 that the corrosion inhibition rate is 83.62%.

[0088] Comparative Example 4 of the present application is a comparative example different from Example 5. Its raw material components and preparation method are basically the same as those of Example 5. The difference is that the main corrosion inhibitor added to the components of step (2) is replaced by 235.71g of substitute 2 (prepared in Example 2) and 94.29g of (3-acrylamidopropyl)trimethylammonium chloride. It can be seen from the data in Table 1 that the corrosion inhibition rate is 84.86%.

[0089] Comparative Example 5 of the present application is different from Example 5. Its raw material components and preparation method are basically the same as those of Example 5. The difference is that the main corrosion inhibitor added to the components of step (2) is replaced by an equal weight of 2-p-chlorobenzylbenzimidazole. It can be seen from the data in Table 1 that the corrosion inhibition rate is 69.65%.

[0090] The raw material components and preparation method of the corrosion inhibitor for petroleum refining distillation equipment used in Comparative Example 6 of the present application are different from those in Example 5. As can be seen from the data in Table 1, its corrosion inhibition rate is 83.12%.

[0091] Comparative Example 7 of the present application is a corrosion inhibitor prepared using the raw materials and method of Example 6 in Publication No. CN111621791A. As can be seen from the data in Table 1, its corrosion inhibition rate is 85.69%.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in this field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A corrosion inhibitor for a petroleum refining distillation unit, characterized in that: The invention comprises the following raw materials in parts by weight: Corrosion inhibitor main agent: 30-35 parts, Synergist: 4-5 parts, Emulsifier: 8-12 parts, Propynol: 2-3 parts, Triethanolamine: 6-10 parts, Deionized water: 120 parts; The main corrosion inhibitor is prepared by the following method: S1: Add cyanuric chloride, 1H-benzo[D]imidazol-7-amine and anhydrous Na2CO3 to a reaction container in sequence, stir and mix, react at 0-5°C for 3-5h, then add 1H-benzo[D]imidazol-7-amine, warm to room temperature and react for 44-48h to obtain the substituent 1; S2: Add the substituent 1, 1-amino-10-undecene and anhydrous Na2CO3 into a reaction vessel in sequence, stir and mix, raise the temperature to 90-95°C and react for 12-18h to obtain the substituent 2; S3: Add tetrahydrofuran, substituent 2, (3-acrylamidepropyl)trimethylammonium chloride and azobisisobutyronitrile into the reaction container in sequence, stir and mix, raise the temperature to 60-80° C., react for 14-18 hours, and obtain the main agent of the copolymer corrosion inhibitor.

2. A corrosion inhibitor for a petroleum refining distillation unit according to claim 1, characterized in that: The number average molecular weight of the main corrosion inhibitor is 10000-22000.

3. A corrosion inhibitor for a petroleum refining distillation unit according to claim 1, characterized in that: In step S1, the mass ratio of cyanuric chloride, 1H-benzo[D]imidazole-7-amine added for the first time, 1H-benzo[D]imidazole-7-amine added for the second time, and anhydrous Na2CO3 is 19:(10-16):(10-16):(20-24).

4. A corrosion inhibitor for a petroleum refining distillation unit according to claim 1, characterized in that: In step S2, the mass ratio of the substituent 1, 1-amino-10-undecene and anhydrous Na2CO3 is 38:(18-22):(10-12).

5. The corrosion inhibitor for a petroleum refining distillation unit according to claim 1, characterized in that: In step S3, the mass ratio of tetrahydrofuran, substituent 2, (3-acrylamidepropyl)trimethylammonium chloride and azobisisobutyronitrile is 100:(22-28):(8-12):(0.14-0.18).

6. A corrosion inhibitor for a petroleum refining distillation unit according to claim 1, characterized in that: The synergist is one of potassium iodide, antimony trioxide and antimony trichloride.

7. A corrosion inhibitor for a petroleum refining distillation unit according to claim 1, characterized in that: The emulsifier is one of sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate.

8. A method for preparing the corrosion inhibitor for petroleum refining distillation equipment according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Weigh the following by weight: corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, triethanolamine, and deionized water; (2) Deionized water, corrosion inhibitor main agent, synergist, emulsifier, propargyl alcohol, and triethanolamine are added to the reactor in sequence, stirred evenly, heated to 50-60° C., and kept warm for 1-2 hours to obtain a corrosion inhibitor for a petroleum refining distillation unit.

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