A preparation method of a neutralizing agent

Abstract

The present application relates to the technical field of neutralizers, and specifically discloses a method for preparing a neutralizer. A method for preparing a neutralizer comprises synthesizing a terminal hydroxyl hyperbranched polyester with good film-forming stability, and then mixing the terminal hydroxyl hyperbranched polyester with an organic amine to prepare a neutralizer. The neutralizer prepared in the present application has the advantage of corrosion inhibition.

Description

Technical Field

[0001] The present application relates to the technical field of neutralizing agents, and more specifically, to a method for preparing a neutralizing agent. Background Art

[0002] During the crude oil refining process, the top of the atmospheric and vacuum distillation unit is in an acidic and corrosive environment for a long time, in which the main corrosive media are hydrogen chloride and hydrogen sulfide, accompanied by a small amount of carbon dioxide.

[0003] Hydrogen chloride mainly comes from two aspects. On the one hand, although the inorganic chloride contained in crude oil has been desalted during the crude oil pretreatment stage, a small amount of residue still remains. Under the high temperature environment of the distillation unit, these residual salts will undergo hydrolysis reaction to generate hydrogen chloride. On the other hand, there are also organic chlorides in crude oil. Under the high temperature environment of the distillation process, the organic chlorides will decompose and release hydrogen chloride. After hydrogen chloride is dissolved in the primary condensate, the generated chloride ions have a strong penetrating ability. It can penetrate the passivation film on the metal surface, directly adsorb on the metal surface, and form soluble metal chlorides with metal ions. The formation of this metal chloride destroys the integrity of the passivation film, exposes the metal matrix below to the corrosive medium, and aggravates the corrosion of the top of the distillation tower.

[0004] Neutralizers have been used for a long time in the crude oil refining process because of their function of neutralizing acidic corrosive media, and have a good effect in alleviating acidic corrosion at the top of the distillation tower.

[0005] A Chinese patent application document with publication number CN110564449A discloses an organic neutralizer. The organic neutralizer described in the patent application document utilizes a s-triazine-based hyperbranched macromolecular compound to neutralize hydrogen sulfide in the oil refining system, lignin sulfonate as a dispersant, ethanolamine to neutralize hydrochloric acid, acetic acid and sodium acetate to control the acid-base balance and increase the reaction rate, and the components work synergistically to neutralize hydrogen sulfide and hydrochloric acid in the oil refining system, effectively preventing metal oil refining equipment from being corroded.

[0006] In the above-mentioned document, the isotriazine-based hyperbranched macromolecular compound is continuously decomposed and consumed during the neutralization reaction, causing the film layer on the substrate to decompose, making it difficult to play a corrosion-inhibiting role on the equipment for a long time. Summary of the invention

[0007] In order to further improve the corrosion inhibition performance of the neutralizer, the present application provides a method for preparing the neutralizer.

[0008] The present application provides a method for preparing a neutralizing agent, which adopts the following technical solution:

[0009] A method for preparing a neutralizing agent comprises the following steps:

[0010] (1) Maleic anhydride and propylene glycol are mixed uniformly, heated, and reacted to obtain a polymerization intermediate a;

[0011] (2) Under nitrogen bubbling conditions, diethanolamine and phthalic anhydride are mixed evenly, nitrogen bubbling is stopped, the temperature is increased, and the reaction is carried out to obtain a polymer intermediate b;

[0012] (3) pentaerythritol and water are mixed evenly, the temperature is raised, nitrogen is bubbled, and the polymerization intermediate b is added to carry out the first stage branching reaction, and then the polymerization intermediate a and 3,5-dihydroxybenzoic acid are added and mixed evenly, and the second stage branching reaction is carried out to obtain a terminal hydroxyl hyperbranched polyester;

[0013] (4) The organic amine, the terminal hydroxyl hyperbranched polyester and the surfactant are uniformly mixed to obtain a neutralizing agent.

[0014] By adopting the above technical scheme, terminal hydroxyl hyperbranched polyester is added to the neutralizer, and while neutralizing the hydrochloric acid, a dense and stable protective film is formed on the metal surface of the top of the distillation tower, preventing corrosive substances from continuing to contact the metal surface of the distillation tower, thereby playing a good protective role on the top of the distillation tower.

[0015] Preferably, in step (1), the mass ratio of maleic anhydride to glycerol is 1:(1-1.2).

[0016] By adopting the above technical solution, the anhydride group of maleic anhydride and the hydroxyl group of propylene glycol can react more fully to form a polyester structure with certain regularity, and excessive cross-linking will not be caused by excessive anhydride. Since the reaction is relatively sufficient, the generated chemical bonds are relatively stable, and the molecular chains of the product are connected more tightly through ester bonds. In a high temperature environment, these ester bonds are not easy to break, which improves the stability of the terminal hydroxyl hyperbranched polyester film and can still play a good corrosion inhibition role at the top of the distillation tower at a higher temperature.

[0017] Preferably, in step (2), the reaction parameters are: temperature 60-70° C., time 1-1.5 h.

[0018] By adopting the above technical solution, the prepared polymer intermediate b has a relatively regular structure. At the same time, the occurrence of side reactions is avoided, and the formation of amide bonds is promoted. The existence of amide bonds enhances the interaction between molecular chains, thereby making the structure of the terminal hydroxyl hyperbranched polyester film more compact, improving mechanical properties, and making it more difficult for corrosive substances to penetrate into the membrane and react with the metal at the top of the distillation tower, effectively preventing the top of the distillation tower from being corroded.

[0019] Preferably, in step (3), the mass ratio of the polymer intermediate a, the polymer intermediate b and 3,5-dihydroxybenzoic acid is (1.3-1.7):1:(0.4-0.6).

[0020] By adopting the above technical scheme, the polymer intermediate a, the polymer intermediate b and 3,5-dihydroxybenzoic acid cooperate with each other to form a relatively compact core structure of the terminal hydroxyl hyperbranched polyester center, and the polymer intermediate a with more peripheral parts is wrapped around the center, while 3,5-dihydroxybenzoic acid is interspersed therein to play a role of auxiliary support and connection, thereby making the terminal hydroxyl hyperbranched polyester film better cover the surface of the base of the distillation tower top, improving the coverage quality and integrity of the film, and making it have a good corrosion inhibition effect.

[0021] Preferably, in step (3), the time of the first-stage branching reaction is 1.5-2.5 h, and the time of the second-stage branching reaction is 3.5-5 h.

[0022] By adopting the above technical solution, the degree of branching of the terminal hydroxyl hyperbranched polyester can be effectively controlled. The first stage branching reaction initially constructs a branching framework, and the second stage branching fully reacts on this basis, so that the molecules form an orderly and complex stable structure with controllable size and shape. This structure enables the terminal hydroxyl hyperbranched polyester to be more evenly distributed on the base of the distillation tower top when forming a film, avoiding local agglomeration or uneven thickness, thereby improving the quality and uniformity of the film, and further improving the protective ability of the terminal hydroxyl hyperbranched polyester on the distillation tower top.

[0023] Preferably, in step (3), the nitrogen flow rate during nitrogen bubbling is 40-60 mL / min.

[0024] Preferably, in step (4), the organic amine consists of ethanolamine and ethyleneamine.

[0025] By adopting the above technical solution, the neutralization reaction between ethanolamine and ethyleneamine and acidic corrosive substances is relatively mild, the occurrence of side reactions is reduced, and the generated salt will not cause secondary corrosion to the top of the distillation tower. In addition, after protonation, ethanolamine and ethyleneamine can be well adsorbed on the metal surface of the top of the distillation tower, filling a small amount of pores between the terminal hydroxyl hyperbranched polyester membranes, and preventing the metal at the top of the distillation tower from being corroded.

[0026] Preferably, in step (4), the mass ratio of the organic amine, the terminal hydroxyl hyperbranched polyester and the surfactant is (65-100):(30-45):1.

[0027] By adopting the above technical scheme, the prepared neutralizer has good neutralization performance and avoids damage to the top of the distillation tower caused by excessive neutralization; the neutralizer has good storage stability. After being injected into the top of the distillation tower, it is evenly dispersed in the acidic corrosive substance system and can quickly and fully play the role of neutralization and corrosion inhibition.

[0028] Preferably, in step (4), the surfactant is one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether and cocamidopropyl betaine.

[0029] Preferably, the mass ratio of ethanolamine to ethyleneamine is 1:(2.1-2.5).

[0030] In summary, this application has the following beneficial effects:

[0031] 1. Hyperbranched polyester forms a thin film on the metal surface, preventing corrosive gases and liquids from continuing to contact the metal inner surface of the distillation tower, thus achieving a corrosion-inhibiting effect; after being terminally hydroxylated, its solubility in water is improved, and it can neutralize hydrochloric acid and combine with chloride ions in hydrochloric acid to prevent chloride ions from continuing to penetrate into the metal inner surface of the distillation tower, thereby reducing chloride ion corrosion.

[0032] 2. In the preparation process of the terminal hydroxyl hyperbranched polyester, 3,5-dihydroxybenzoic acid and ethylene glycolamine are introduced to improve the stability of the terminal hydroxyl hyperbranched polyester. The nitrogen atom and the carbonyl group produce a conjugated effect, which weakens the positive charge of the carbonyl carbon and reduces its sensitivity to nucleophilic reagents, thereby improving the stability of the ester group. Due to the presence of the II-II conjugated system between the benzene rings, the density of the terminal hydroxyl hyperbranched polyester when forming a film layer is increased, preventing corrosive substances from contacting the metal inner surface of the distillation tower.

[0033] 3. The solubility of organic amines in the water phase is higher than that in the oil phase, and they can be discharged with the water phase without causing pollution to the oil products. The surfactant improves the compatibility between the organic amines and the terminal hydroxyl hyperbranched polyester, making the neutralizer uniform and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a titration curve diagram of the neutralizer prepared in Example 1 of the present application.

[0035] Figure 2 It is a graph of the corrosion inhibition performance of the neutralizers prepared in the examples and comparative examples of the present application. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to the embodiments.

[0037] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0038] Example 1

[0039] The preparation method of the neutralizer of this embodiment comprises the following steps:

[0040] (1) 100 g of maleic anhydride and 100 g of propylene glycol were placed in a flask, heated to 65°C, and stirred for 30 min until the maleic anhydride was completely dissolved. The stirring was continued until the stratification in the solution completely disappeared, and a polymer intermediate a was obtained.

[0041] (2) Under nitrogen bubbling conditions, 110 g of diethanolamine and 150 g of phthalic anhydride were mixed evenly, the nitrogen was stopped, the temperature was raised to 60°C, and the reaction was kept at this temperature for 1.5 hours to obtain a polymer intermediate b;

[0042] (3) 5 g of pentaerythritol and 15 g of water were mixed, the temperature was raised to 140°C, nitrogen bubbling was performed at a nitrogen flow rate of 40 mL / min, 100 g of polymerization intermediate b was added, the reaction was continued for 1.5 h, and then 130 g of polymerization intermediate a and 60 g of 3,5-dihydroxybenzoic acid were added, and the reaction was continued for 5 h to obtain a terminal hydroxyl hyperbranched polyester;

[0043] (4) Mix 4 g of ethylenediamine, 15 g of diethylenetriamine, 6 g of piperazine, 19 g of triethylenetetramine, 4 g of monoethanolamine, 10 g of N-methylethanolamine, 2 g of diethanolamine, 5 g of N-methyldiethanolamine, 30 g of terminal hydroxyl hyperbranched polyester and 1 g of fatty alcohol polyoxyethylene ether, raise the temperature to 40°C, and stir for 30 min to obtain a neutralizing agent.

[0044] Example 2

[0045] The preparation method of the neutralizer of this embodiment comprises the following steps:

[0046] (1) 100 g of maleic anhydride and 120 g of propylene glycol were placed in a flask, heated to 65°C, and stirred for 30 min until the maleic anhydride was completely dissolved. The stirring was continued until the stratification in the solution completely disappeared, and a polymerization intermediate a was obtained.

[0047] (2) Under nitrogen bubbling conditions, 120 g of diethanolamine and 150 g of phthalic anhydride were mixed evenly, the nitrogen was stopped, the temperature was raised to 70°C, and the reaction was kept at this temperature for 1 hour to obtain a polymer intermediate b;

[0048] (3) 6 g of pentaerythritol and 15 g of water were mixed, the temperature was raised to 140°C, nitrogen bubbling was performed at a nitrogen flow rate of 60 mL / min, 100 g of polymerization intermediate b was added, the reaction was continued for 2.5 h, and then 170 g of polymerization intermediate a and 40 g of 3,5-dihydroxybenzoic acid were added, and the reaction was continued for 3.5 h to obtain a terminal hydroxyl hyperbranched polyester;

[0049] (4) Mix 10 g of ethylenediamine, 25 g of diethylenetriamine, 6.5 g of piperazine, 30 g of triethylenetetramine, 5 g of monoethanolamine, 10 g of N-methylethanolamine, 5 g of diethanolamine, 8.5 g of N-methyldiethanolamine, 45 g of terminal hydroxyl hyperbranched polyester and 1 g of alkylphenol polyoxyethylene ether, heat to 60°C, and stir for 30 min to obtain a neutralizing agent.

[0050] Example 3

[0051] The preparation method of the neutralizer of this embodiment comprises the following steps:

[0052] (1) 100 g of maleic anhydride and 110 g of propylene glycol were placed in a flask, heated to 65°C, and stirred for 30 min until the maleic anhydride was completely dissolved. The stirring was continued until the stratification in the solution completely disappeared, and a polymer intermediate a was obtained.

[0053] (2) Under nitrogen bubbling conditions, 115 g of diethanolamine and 150 g of phthalic anhydride were mixed evenly, the nitrogen was stopped, the temperature was raised to 68°C, and the reaction was kept at this temperature for 1.2 hours to obtain a polymer intermediate b;

[0054] (3) 6 g of pentaerythritol and 15 g of water were mixed, the temperature was raised to 140°C, nitrogen bubbling was performed at a nitrogen flow rate of 55 mL / min, 100 g of polymerization intermediate b was added, the reaction was continued for 2.3 h, and then 150 g of polymerization intermediate a and 42 g of 3,5-dihydroxybenzoic acid were added, and the reaction was continued for 4 h to obtain a terminal hydroxyl hyperbranched polyester;

[0055] (4) Mix 10 g of ethylenediamine, 15 g of diethylenetriamine, 10 g of piperazine, 20 g of triethylenetetramine, 5 g of monoethanolamine, 10 g of N-methylethanolamine, 3 g of diethanolamine, 7 g of N-methyldiethanolamine, 35 g of terminal hydroxyl hyperbranched polyester and 1 g of cocamidopropyl betaine, heat to 45°C, and stir for 30 min to obtain a neutralizing agent.

[0056] Comparative Example 1

[0057] The preparation method of the neutralizing agent of this comparative example comprises the following steps:

[0058] (1) 100 g of maleic anhydride and 100 g of propylene glycol were placed in a flask, heated to 65°C, and stirred for 30 minutes until the maleic anhydride was completely dissolved. The stirring was continued until the stratification in the solution completely disappeared, thereby obtaining a polymer intermediate.

[0059] (3) 5 g of pentaerythritol and 15 g of water were mixed, the temperature was raised to 140° C., nitrogen bubbling was performed at a nitrogen flow rate of 40 mL / min, 130 g of the polymerization intermediate and 60 g of 3,5-dihydroxybenzoic acid were added, and the reaction was carried out for 5 h to obtain a terminal hydroxyl hyperbranched polyester;

[0060] (4) Mix 4 g of ethylenediamine, 15 g of diethylenetriamine, 6 g of piperazine, 19 g of triethylenetetramine, 4 g of monoethanolamine, 10 g of N-methylethanolamine, 2 g of diethanolamine, 5 g of N-methyldiethanolamine, 30 g of terminal hydroxyl hyperbranched polyester and 1 g of fatty alcohol polyoxyethylene ether, raise the temperature to 40°C, and stir for 30 min to obtain a neutralizing agent.

[0061] Comparative Example 2

[0062] The preparation method of the neutralizing agent of this comparative example comprises the following steps:

[0063] (1) 100 g of maleic anhydride and 100 g of propylene glycol were placed in a flask, heated to 65°C, and stirred for 30 min until the maleic anhydride was completely dissolved. The stirring was continued until the stratification in the solution completely disappeared, and a polymer intermediate a was obtained.

[0064] (2) Under nitrogen bubbling conditions, 110 g of diethanolamine and 150 g of phthalic anhydride were mixed evenly, the nitrogen was stopped, the temperature was raised to 60°C, and the reaction was kept at this temperature for 1.5 hours to obtain a polymer intermediate b;

[0065] (3) 5 g of pentaerythritol and 15 g of water were mixed, the temperature was raised to 140°C, nitrogen bubbling was performed at a nitrogen flow rate of 40 mL / min, 100 g of polymerization intermediate b was added, the reaction was continued for 1.5 h, and then 190 g of polymerization intermediate a was added, and the reaction was continued for 5 h to obtain a terminal hydroxyl hyperbranched polyester;

[0066] (4) Mix 4 g of ethylenediamine, 15 g of diethylenetriamine, 6 g of piperazine, 19 g of triethylenetetramine, 4 g of monoethanolamine, 10 g of N-methylethanolamine, 2 g of diethanolamine, 5 g of N-methyldiethanolamine, 30 g of terminal hydroxyl hyperbranched polyester and 1 g of fatty alcohol polyoxyethylene ether, raise the temperature to 40°C, and stir for 30 min to obtain a neutralizing agent.

[0067] Performance testing

[0068] 1. pH control performance of neutralizer: Take 0.1g of the neutralizer prepared in Example 1 and add it to a beaker, then add 10g of water and mix well, titrate with a standard HCl solution with a molar concentration of 0.1mol / L, and measure the pH value of the solution with an acidity meter, record the pH value change and the volume of HCl consumed, and draw a neutralization titration curve, as shown in FIG. Figure 1 shown.

[0069] 2. Corrosion scraper experiment: Select a carbon steel specimen with a length of 3cm, a width of 2cm, and a thickness of 0.2mm, polish it with sandpaper until it is bright, wash it once with dilute hydrochloric acid, wash it once with water, wash it twice with anhydrous alcohol, quickly air-dry it, and weigh it; add 500mL of corrosive medium into a conical flask, the corrosive medium is 1000mg / L HCl+1000mg / L NaCl+200mg / L H2S aqueous solution, heat it to 90°C, and then hang the carbon steel specimen in it so that the carbon steel specimen is completely immersed in the corrosive medium, then add a neutralizer, and keep it still for 6 hours; take out the carbon steel specimen, wash it once with dilute hydrochloric acid, wash it once with water, wash it twice with anhydrous alcohol, quickly air-dry it, and weigh it. The blank control experiment method is the same as above, except that no neutralizer is added. The corrosion inhibition performance of the neutralizer is measured as follows Figure 2 shown.

[0070] Analyze Examples 1-3, Comparative Example 1 and Comparative Example 2 and combine Figure 1 and Figure 2 It can be seen that the neutralizer prepared in the present application can effectively control the pH value within the range of 6.5-7.5, and the neutralizer prepared in the present application has good corrosion inhibition performance.

[0071] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a neutralizing agent, characterized in that: The steps include: (1) Maleic anhydride and propylene glycol are mixed uniformly, heated, and reacted to obtain a polymerization intermediate a; (2) Under nitrogen bubbling conditions, diethanolamine and phthalic anhydride are mixed evenly, nitrogen bubbling is stopped, the temperature is increased, and the reaction is carried out to obtain a polymer intermediate b; (3) pentaerythritol and water are mixed evenly, the temperature is raised, nitrogen is bubbled, and the polymerization intermediate b is added to carry out the first stage branching reaction, and then the polymerization intermediate a and 3,5-dihydroxybenzoic acid are added and mixed evenly, and the second stage branching reaction is carried out to obtain a terminal hydroxyl hyperbranched polyester; (4) uniformly mixing the organic amine, the terminal hydroxyl hyperbranched polyester and the surfactant to obtain a neutralizing agent; The organic amine is composed of ethanolamine and ethyleneamine; The surfactant is one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether and cocamidopropyl betaine.

2. The method for preparing a neutralizing agent according to claim 1, characterized in that: In the step (1), the mass ratio of maleic anhydride to propylene glycol is 1:(1-1.2).

3. The method for preparing a neutralizing agent according to claim 2, characterized in that: In the step (2), the reaction parameters are: temperature 60-70°C, time 1-1.5h.

4. The method for preparing a neutralizing agent according to claim 1, characterized in that: In the step (3), the mass ratio of the polymer intermediate a, the polymer intermediate b and 3,5-dihydroxybenzoic acid is (1.3-1.7):1:(0.4-0.6).

5. The method for preparing a neutralizing agent according to claim 1, characterized in that: In the step (3), the time of the first-stage branching reaction is 1.5-2.5 hours, and the time of the second-stage branching reaction is 3.5-5 hours.

6. The method for preparing a neutralizing agent according to claim 1, characterized in that: In the step (3), the nitrogen flow rate during nitrogen bubbling is 40-60 mL / min.

7. The method for preparing a neutralizing agent according to claim 1, characterized in that: In the step (4), the mass ratio of the organic amine, the terminal hydroxyl hyperbranched polyester and the surfactant is (65-100):(30-45):

1.

8. The method for preparing a neutralizing agent according to claim 1, characterized in that: The mass ratio of the ethanolamine to the ethyleneamine is 1:(2.1-2.5).

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