Preparation method of copper sheet corrosion inhibitor for gasoline and diesel components produced as by-products from waste lubricating oil hydrogenation

Abstract

The present invention discloses a method for preparing a copper sheet corrosion inhibitor for gasoline and diesel components produced as byproducts from the hydrogenation of waste lubricating oils, belonging to the technical field of petroleum product corrosion inhibition. The method comprises preparing a saturated isooctane / n-hexadecane solution of tetrazole; preparing an n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole; mixing dropwise, adjusting the pH, and heating in a water bath; adding organic cerium, cooling, and aging the solution. The copper sheet corrosion inhibitor for gasoline and diesel components produced as byproducts from the hydrogenation of waste lubricating oils prepared using this method can significantly reduce the corrosion level of the copper sheet produced as a byproduct from the hydrogenation of waste lubricating oils, even at a very low dosage, thereby achieving the technical purpose of inhibiting copper sheet corrosion.

Description

Technical Field

[0001] The invention relates to a method for preparing a petroleum product additive, in particular to a method for preparing a copper sheet corrosion inhibitor for gasoline and diesel components produced as by-products from waste lubricating oil hydrogenation, and belongs to the technical field of petroleum product corrosion inhibition. Background Art

[0002] Waste lubricant oil recycling is not only environmentally friendly but also economically beneficial. Methods such as clay refining have been eliminated due to environmental pollution and low recovery rates. Hydrofining is currently the mainstream process for waste lubricant oil recycling.

[0003] Chinese patent application number 201510060139.X describes a hydrorefining process for waste lubricating oil. The waste lubricating oil undergoes dehydration, impurity removal, and heaviness removal fractionation, followed by two-stage hydrorefining. After dechlorination, it is cooled and separated to produce lubricating base oil and gasoline and diesel blending components. The lubricating base oil is a heavy component, while the gasoline and diesel components are light components. Occasionally, trace amounts of hydrogen sulfide and elemental sulfur may be present, causing copper corrosion failure. However, the China VI standard for gasoline and diesel requires Level 1 corrosion resistance for copper.

[0004] Benzotriazole is commonly used as a corrosion inhibitor. Patent application number 201710242249.7 describes its synthesis method, but it is more suitable for use with light hydrocarbons such as liquefied petroleum gas. When used in gasoline and diesel blending components, which are byproducts of waste lubricating oil hydrogenation, the dosage is high, resulting in poor stability and economic efficiency. Patent application number 202010150520.6 describes the inhibitory effect of benzotriazole-derived esters on copper corrosion. However, due to its long carbon chain, it is suitable for lubricating base oils, but its solubility and diffusion in gasoline and diesel components are relatively poor. Summary of the Invention

[0005] In order to avoid the copper sheet corrosion failure of gasoline and diesel components caused by trace amounts of hydrogen sulfide and elemental sulfur entrained in the light components of lubricating oil hydrogenation, it is necessary to develop a copper sheet corrosion inhibitor that is particularly suitable for gasoline and diesel components that are by-products of waste lubricating oil hydrogenation. This copper sheet corrosion inhibitor can form a dense protective layer on the surface of the copper sheet, and an extremely low dosage can achieve the effect of inhibiting copper sheet corrosion.

[0006] To achieve the above-mentioned object, the present invention provides a method for preparing a copper sheet corrosion inhibitor for gasoline and diesel components produced as by-products of waste lubricating oil hydrogenation. The technical solution is as follows:

[0007] Step S1, preparing a tetrazole solution in n-octane / n-hexadecane.

[0008] Step S2: preparing an n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole.

[0009] Step S3: Add the n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole prepared in step S2 dropwise to the n-octane / n-hexadecane solution of tetrazole prepared in step S1, adjust the pH value of the solution to 7.5-8, and heat in a 55° C. water bath.

[0010] Step S4: adding organic cerium to the solution obtained in step S3, fully stirring, cooling, and aging for 8 hours to obtain a copper sheet corrosion inhibitor for gasoline and diesel components as a by-product of waste lubricating oil hydrogenation.

[0011] As a further improvement of the present invention, the solvent used in step S1 and step S2 is a mixed solvent of n-octane and n-hexadecane, which simulates the gasoline and diesel components produced as by-products of waste lubricating oil hydrogenation and obtains optimal mutual solubility, with a mass ratio of 1:4 to 1:6.

[0012] As a further improvement of the present invention, the n-octane / n-hexadecane solution for preparing tetrazole in step S1 is in a saturated state at 25° C., and the clear liquid is collected by filtration.

[0013] As a further improvement of the present invention, the mass concentration of the 8-hydroxyquinoline or imidazole solution used in step S2 is 10% to 20%.

[0014] As a further improvement of the present invention, 8-hydroxyquinoline or imidazole solution is added dropwise to the tetrazole solution, with the volume ratio of 8-hydroxyquinoline or imidazole solution to saturated tetrazole solution being 1:10, and the pH value is controlled at 7.5-8.

[0015] As a further improvement of the present invention, the organic cerium reagent is prepared by exchanging anhydrous cerium trichloride with phenyl lithium and is prepared and used immediately. The amount of organic cerium added is calculated based on the mass of elemental cerium, and 0.1-0.2 g of cerium is added per liter of tetrazolium solution.

[0016] As a further improvement of the present invention, the organic cerium needs to be added when the solution temperature is controlled at 55° C., and after being fully dissolved, it is aged for 8 hours.

[0017] The main principles of the present invention:

[0018] Tetrazolium forms a protective metal complex film on the surface of copper metal, blocking the exchange of substances inside and outside the film, thereby isolating S from contact with the copper sheet.

[0019] 8-Hydroxyquinoline or imidazole can repair the defects of the tetrazole and copper complex protective film.

[0020] The synergistic effect of organic cerium makes the distribution of the complex protective film more uniform and improves the utilization rate of tetrazole.

[0021] The invention is suitable for inhibiting the corrosion of copper sheets of gasoline and diesel components produced as by-products of waste lubricating oil hydrogenation. Compared with the prior art, the invention has the following advantages:

[0022] Compared with benzotriazole, which is commonly used as a traditional copper corrosion inhibitor, tetrazole molecules are smaller and take less time to form a metal complex protective film on the surface of metallic copper, making it more efficient.

[0023] The combination of 8-hydroxyquinoline or imidazole and tetrazole can repair the defective positions of the metal complex protective film, which is not possible when benzotriazole is used alone.

[0024] The synergistic effect of organic cerium can promote the formation of a more uniform complex protective film of tetrazole on the copper surface, thereby improving the utilization rate of tetrazole and reducing the amount of the copper sheet corrosion inhibitor used. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the embodiments.

[0026] GB17930-2016 Motor Gasoline and GB19147-2016 Motor Diesel both require that the copper corrosion of gasoline and diesel should not exceed level 1. In the examples, all test methods strictly refer to GB / T 5096-2017 Petroleum Products Copper Corrosion Test Method. Example 1

[0027] Preparation of copper sheet corrosion inhibitor based on gasoline and diesel components produced as by-products from waste lubricating oil hydrogenation

[0028] S1. Dissolve 500g of tetrazole in 1L of n-octane / n-hexadecane (mass ratio 1:4) and filter at 25°C to obtain the clear solution. (Hereinafter referred to as Formula 1)

[0029] S2. Dissolve 10 g of 8-hydroxyquinoline in 100 mL of n-octane / n-hexadecane (mass ratio 1:4), add it dropwise to the solution prepared in Formula 1, and adjust the pH to 8. (hereinafter referred to as Formula 2)

[0030] S3. Take 0.176g of cerium trichloride and exchange it with phenyl lithium to obtain organic cerium. Add it to the solution prepared in Formula 2 heated to 55°C in a water bath, stir, cool, and age for 8 hours. (hereinafter referred to as Formula 3)

[0031] Take 5L of oil sample from a tank with unqualified gasoline and diesel mixed components produced by a waste lubricating oil hydrogenation unit in Tianmen, Hubei Province, and add 1g of analytical pure sublimed sulfur to it for testing. The results are shown in Table 1:

[0032] Table 1 Comparison of formulas for copper sheet corrosion inhibitors for gasoline and diesel components produced as by-products from waste lubricating oil hydrogenation

[0033]

[0034] As shown in Table 1, the inhibitors prepared from all three formulations significantly inhibited copper corrosion in the oil sample. Formulations 2 and 3 showed significantly greater inhibition than Formulation 1. The tetrazole / 8-hydroxyquinoline / cerium salt combination exhibited a significant advantage. Example 2

[0035] Preparation of copper sheet corrosion inhibitor based on gasoline and diesel components produced as by-products from waste lubricating oil hydrogenation

[0036] S1. Dissolve 500 g of tetrazole in 1 L of n-octane / n-hexadecane (volume ratio 1:6) and filter at 25°C to obtain the clear solution.

[0037] S2. Dissolve 20 g of imidazole in 100 mL of n-octane / n-hexadecane (volume ratio 1:6), add the solution dropwise to the solution prepared in the previous step, and adjust the pH to 7.5.

[0038] S3. Take 0.352 g of cerium trichloride and exchange it with phenyllithium to produce organocerium. Add it to the solution prepared in the previous step, heated to 55°C in a water bath. Stir, cool, and age for 8 hours. This produces a copper corrosion inhibitor for gasoline and diesel components produced as a byproduct of waste lubricating oil hydrogenation (hereinafter referred to as the inventive agent).

[0039] A copper sheet corrosion inhibitor sold commercially by a company in Suqian, Jiangsu Province was used as a reference group (the main ingredient was benzotriazole, hereinafter referred to as the reference agent).

[0040] Oil samples from a waste lubricating oil hydrotreating unit in Tianmen, Hubei Province, which produced unqualified gasoline and diesel blending components, were collected every other day for testing. The results are shown in Table 2:

[0041] Table 2 Comparison of copper sheet corrosion inhibitors for gasoline and diesel components produced as by-products from waste lubricating oil hydrogenation

[0042]

[0043] It can be determined from Table 2 that, in the unqualified gasoline and diesel component production line produced by waste lubricating oil hydrogenation, the copper sheet corrosion inhibitor prepared by the method of the present invention can make the copper sheet corrosion of the gasoline and diesel component of the waste lubricating oil hydrogenation byproduct, which was originally unqualified, pass the test.

[0044] When the corrosion of the raw copper sheets on the production line reached Level 3 on the first and fifth days, the reference agent required a dosage of at least 100 ppm, while the inventive agent only required 10-20 ppm to meet the standard, requiring only one-fifth to one-tenth the dosage of the reference agent. A horizontal comparison showed that when the inhibitor dosages were 5 ppm, 10 ppm, 20 ppm, and 50 ppm, the inventive agent consistently outperformed the reference agent in inhibiting copper sheet corrosion, confirming that the smaller tetrazole molecule forms a metal complex protective film on the copper surface more quickly and efficiently.

[0045] The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Based on the technical solution of the present invention, various modifications or replacements that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing a copper sheet corrosion inhibitor from gasoline and diesel components produced as by-products of waste lubricating oil hydrogenation, characterized in that: The preparation method of the copper sheet corrosion inhibitor comprises the following steps: Step S1, preparing a tetrazole n-octane / n-hexadecane solution; The solution prepared in step S1 is a saturated solution at 25°C, and the clear solution is obtained by filtration; Step S2, preparing an n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole; In step S2, the mass concentration of the n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole is prepared to be 10% to 20%; Step S3, adding the n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole prepared in Step S2 dropwise to the clear solution prepared in Step S1; In step S3, the volume ratio of the n-octane / n-hexadecane solution of 8-hydroxyquinoline or imidazole to the n-octane / n-hexadecane solution of tetrazole is 1:10; Step S4, adding organic cerium to the solution prepared in step S3; In step S4, organic cerium is prepared by exchanging anhydrous cerium trichloride with phenyl lithium and is prepared and used immediately. The amount of organic cerium added is calculated based on the mass of elemental cerium: 0.1-0.2 g of cerium is added per liter of tetrazole n-octane / n-hexadecane solution. The organic cerium needs to be added when the solution temperature is controlled at 55° C., and after being fully dissolved, it is aged for 8 hours.

2. The preparation method according to claim 1, characterized in that The mass ratio of n-octane to n-hexadecane in step S1 and step S2 is 1:4 to 1:6.

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