Corrosion-resistant metal bent pipe for petrifaction and preparation method of corrosion-resistant metal bent pipe

Abstract

The invention discloses a corrosion-resistant metal bent pipe for petrifaction and a preparation method of the corrosion-resistant metal bent pipe, and relates to the technical field of metal bent pipes, the corrosion-resistant metal bent pipe applied to the petrifaction field is prepared, a dopamine solution is used for dipping the metal bent pipe, and the corrosion resistance of the metal bent pipe is improved. The invention discloses a zeolite imidazole skeleton-zinc oxide composite material. The zeolite imidazole framework material can effectively isolate corrosive ions, has excellent corrosion resistance and large specific surface area, can be grafted with polyethyleneimine of a large amount of glycine to form a modified zeolite imidazole framework material, and the zigzag surface of the modified zeolite imidazole framework material can further prevent corrosion of corrosive media. And the modified zeolite imidazole framework material and the nano-zinc oxide are compounded together, so that the dispersity of the nano-zinc oxide is improved, and the corrosion resistance of the metal elbow pipe is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal pipe bends, in particular to a corrosion-resistant metal pipe bend for petrochemical use and a preparation method thereof. Background Art

[0002] Metal elbows are widely used as connectors in hydropower, petroleum, construction natural gas, chemical industry and other fields, playing a vital role in the transportation of media. In the petrochemical field, petrochemical products often work under high temperature and high pressure environment, and are often exposed to highly corrosive chemicals. Ordinary metal elbows are prone to corrosion and damage under such conditions. Although the existing technology provides some corrosion-resistant alloys, in practical applications, there are still problems such as insufficient durability, complex manufacturing process and high cost.

[0003] In order to solve the above problems and improve the corrosion resistance of the corrosion-resistant metal elbow for petrochemical use, the present invention provides a corrosion-resistant metal elbow for petrochemical use and a preparation method thereof. Summary of the invention

[0004] The object of the present invention is to provide a corrosion-resistant metal elbow for petrochemical use and a preparation method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a corrosion-resistant metal elbow for petrochemical use comprises the following steps: Step 1: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1550-1600℃ to melt, then cast them, cool them to form, cut and grind them to obtain a metal elbow; Step 2: Take the pretreated nano zinc oxide and anhydrous ethanol, stir evenly, add n-dodecyl mercaptan, heat to 60-65°C, stir for 2-3h, add modified zeolite imidazole framework material, stir for 6-8h, filter, wash and dry to obtain zeolite imidazole framework-zinc oxide composite material; Step 3: Take the metal elbow, clean it, dry it, and then immerse it in the dopamine solution for 1-2 hours, add the Tris-HCl solution containing the zeolite imidazole framework-zinc oxide composite material, continue to immerse it for 5-6 hours, take it out, dry it, and obtain a corrosion-resistant metal elbow for petrochemical use.

[0006] More optimally, the preparation method of the modified zeolite imidazole framework material comprises the following steps: S1: Take glycine, branched polyethyleneimine, and deionized water, stir evenly, add tert-butyl hydroperoxide dropwise, reflux at 80-85°C for 3.5-5h under inert gas protection, remove the solvent by reduced pressure distillation, add anhydrous methanol, stir evenly, then add aqueous hydrochloric acid solution, precipitate, centrifuge, dry, add deionized water, stir evenly, add sodium carbonate, adjust the pH value to 8.0, then dialyze with deionized water, freeze, and dry to obtain polyethyleneimine grafted with glycine; S2: Take zeolite imidazole framework material and deionized water, stir evenly, add polyethyleneimine grafted with glycine, stir for 6-8 hours, filter and dry to obtain modified zeolite imidazole framework material.

[0007] More optimally, the preparation method of the zeolite imidazole framework material is: take 2-methylimidazole, zinc nitrate hexahydrate, and methanol, stir for 1-2 hours, then stand for 24-26 hours, centrifuge, filter, wash, and dry to obtain the zeolite imidazole framework material.

[0008] More optimally, in step 2, the preparation method of the pretreated nano zinc oxide is: take a dopamine solution, add nano zinc oxide, heat to 60-65°C, stir for 7-9h, filter, wash and dry to obtain the pretreated nano zinc oxide.

[0009] More optimally, the preparation method of the dopamine solution is: taking a tris(hydroxymethyl)aminomethane solution, adding hydrochloric acid to adjust the pH value to 8.5 to obtain a Tris-HCl buffer; dissolving dopamine hydrochloride in the Tris-HCl buffer to obtain a dopamine solution.

[0010] More optimally, the metal elbow includes the following components, calculated by mass percentage: 20wt%-22wt% chromium, 7wt%-8wt% nickel, 1.5wt%-2.6wt% silicon, 0.5wt%-1wt% manganese, 0.3wt%-0.5wt% carbon, 0.2wt%-0.4wt% vanadium, 0.1wt%-0.2wt% magnesium, 0.01wt%-0.03wt% cerium, 0.03wt%-0.05wt% phosphorus, and the balance is iron.

[0011] More optimally, in S2, the mass ratio of zeolite imidazole framework material, polyethyleneimine grafted with glycine, and deionized water is: (2-2.5): 1:300.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention prepares a corrosion-resistant metal elbow pipe used in the petrochemical field, and uses a dopamine solution to impregnate the metal elbow pipe, thereby improving the corrosion resistance of the metal elbow pipe.

[0013] 2. The present invention prepares a zeolite imidazole framework-zinc oxide composite material. The zeolite imidazole framework material can effectively isolate corrosive ions, has excellent corrosion resistance, and has a large specific surface area. It can be grafted with a large amount of glycine polyethyleneimine to form a modified zeolite imidazole framework material. The tortuous surface of the modified zeolite imidazole framework material can further prevent the erosion of the corrosive medium. The polyethylenimine is grafted with the zwitterionic surfactant glycine, so that the corrosion resistance of the polyethylenimine is improved, and the surface of the polyethylenimine is loaded with amino groups, which helps the modified zeolite imidazole framework material to be better deposited on the surface of the metal elbow with the assistance of dopamine. The present invention controls the mass ratio of the zeolite imidazole framework material, the polyethylenimine grafted with glycine, and the deionized water to: (2-2.5): 1:300. At this time, the corrosion resistance of the metal elbow is optimal.

[0014] 3. The present invention uses n-dodecyl mercaptan to treat nano zinc oxide, which reduces the surface energy of nano zinc oxide and improves its hydrophobicity, thereby improving the corrosion resistance of the metal elbow. The present invention combines the modified zeolite imidazole framework material with nano zinc oxide, improves the dispersibility of nano zinc oxide, and further improves the corrosion resistance of the metal elbow. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] There is no special restriction on the purchase manufacturers of all raw materials involved in the present invention, and exemplary examples include: branched polyethyleneimine: can be purchased from Sigma-Aldrich, model: 408727; nano zinc oxide: particle size: 10-100 nm.

[0017] Embodiment 1: A method for preparing a corrosion-resistant metal elbow for petrochemical use, comprising the following steps: Step 1: Preparation of metal elbow: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1570℃ to melt, then cast them, cool them into shape, cut them and grind them to get the metal elbow; The metal elbow comprises the following components, calculated by mass percentage: 21wt% chromium, 7.5wt% nickel, 2.0wt% silicon, 0.7wt% manganese, 0.4wt% carbon, 0.3wt% vanadium, 0.15wt% magnesium, 0.02wt% cerium, 0.04% phosphorus, and the balance is iron; Step 2: Preparation of zeolite imidazole framework material: Take 0.52g 2-methylimidazole, 0.85g zinc nitrate hexahydrate, and 50mL methanol, stir for 1.5h, then stand for 25h, centrifuge, filter, wash, and dry to obtain a zeolite imidazole framework material; Step 3: Preparation of polyethyleneimine grafted with glycine: Take 0.8g of glycine, 1g of branched polyethyleneimine, and 30mL of deionized water, stir evenly, add 16µL of tert-butyl hydroperoxide dropwise, and react at 83°C for 4h under the protection of inert gas. Remove the solvent by distillation under reduced pressure, add 80mL of anhydrous methanol, stir evenly, then add 10mL of 10% hydrochloric acid aqueous solution, precipitate, centrifuge, dry, add 100mL of deionized water, stir evenly, add sodium carbonate, adjust the pH value to 8.0, then dialyze with deionized water, freeze, and dry to obtain polyethyleneimine grafted with glycine; Step 4: Preparation of modified zeolite imidazole framework material: Take 2.2 g of zeolite imidazole framework material and 300 mL of deionized water, stir evenly, add 1 g of polyethyleneimine grafted with glycine, stir for 7 h, filter and dry to obtain a modified zeolite imidazole framework material; The mass ratio of zeolite imidazole framework material, polyethyleneimine grafted with glycine, and deionized water is: 2.2:1:300; Step 5: Preparation of pretreated nano zinc oxide: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take 100mL dopamine solution, add 5g nano zinc oxide, heat to 63°C, stir for 8h, filter, wash, and dry to obtain pretreated nano zinc oxide; Step 6: Preparation of zeolite imidazole framework-zinc oxide composite material: Take 5g of pretreated nano zinc oxide and 100mL of anhydrous ethanol, stir evenly, add 1.2mL of n-dodecyl mercaptan dropwise, heat to 63°C, stir for 2.5h, add 1g of modified zeolite imidazole framework material, stir for 7h, filter, wash and dry to obtain a zeolite imidazole framework-zinc oxide composite material; Step 7: Preparation of corrosion-resistant metal elbows for petrochemical applications: Take a 10mmol / L tris(hydroxymethyl)aminomethane solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain a Tris-HCl buffer solution; dissolve dopamine hydrochloride in the Tris-HCl buffer solution to obtain a 2g / L dopamine solution; take a metal elbow, wash it, dry it, and then immerse it in the dopamine solution for 1.5 hours, add a Tris-HCl solution containing 1.5g / L zeolite imidazole framework-zinc oxide composite material with an equal volume to the dopamine solution, continue to immerse for 5.5 hours, take it out, dry it, and obtain a corrosion-resistant metal elbow for petrochemical use.

[0018] Embodiment 2: A method for preparing a corrosion-resistant metal elbow for petrochemical use, comprising the following steps: Step 1: Preparation of metal elbow: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1550℃ to melt, then cast them, cool them into shape, cut them and grind them to get the metal elbow; The metal elbow comprises the following components, calculated by mass percentage: 20wt% chromium, 7wt% nickel, 1.5wt% silicon, 0.5wt% manganese, 0.3wt% carbon, 0.2wt% vanadium, 0.1wt% magnesium, 0.01wt% cerium, 0.03wt% phosphorus, and the balance is iron; Step 2: Preparation of zeolite imidazole framework material: Take 0.52g 2-methylimidazole, 0.85g zinc nitrate hexahydrate, and 50mL methanol, stir for 1h, then stand for 24h, centrifuge, filter, wash, and dry to obtain a zeolite imidazole framework material; Step 3: Preparation of polyethyleneimine grafted with glycine: Take 0.8g of glycine, 1g of branched polyethyleneimine, and 30mL of deionized water, stir evenly, add 16µL of tert-butyl hydroperoxide dropwise, and react at 80°C under inert gas protection for 3.5h. Remove the solvent by distillation under reduced pressure, add 80mL of anhydrous methanol, stir evenly, then add 10mL of 10% hydrochloric acid aqueous solution, precipitate, centrifuge, dry, add 100mL of deionized water, stir evenly, add sodium carbonate, adjust the pH value to 8.0, then dialyze with deionized water, freeze, and dry to obtain polyethyleneimine grafted with glycine; Step 4: Preparation of modified zeolite imidazole framework material: Take 2 g of zeolite imidazole framework material and 300 mL of deionized water, stir evenly, add 1 g of polyethyleneimine grafted with glycine, stir for 6 h, filter and dry to obtain a modified zeolite imidazole framework material; The mass ratio of zeolite imidazole framework material, polyethyleneimine grafted with glycine, and deionized water is 2:1:300; Step 5: Preparation of pretreated nano zinc oxide: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take 100mL dopamine solution, add 5g nano zinc oxide, heat to 60°C, stir for 7h, filter, wash, and dry to obtain pretreated nano zinc oxide; Step 6: Preparation of zeolite imidazole framework-zinc oxide composite material: Take 5g of pretreated nano zinc oxide and 100mL of anhydrous ethanol, stir evenly, add 1.2mL of n-dodecyl mercaptan dropwise, heat to 60°C, stir for 2h, add 1g of modified zeolite imidazole framework material, stir for 6h, filter, wash and dry to obtain a zeolite imidazole framework-zinc oxide composite material; Step 7: Preparation of corrosion-resistant metal elbows for petrochemical applications: Take a 10mmol / L tris(hydroxymethyl)aminomethane solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain a Tris-HCl buffer solution; dissolve dopamine hydrochloride in the Tris-HCl buffer solution to obtain a 2g / L dopamine solution; take a metal elbow, wash it, dry it, and then immerse it in the dopamine solution for 1 hour, add a Tris-HCl solution containing 1.5g / L zeolite imidazole framework-zinc oxide composite material with an equal volume to the dopamine solution, continue to immerse for 5 hours, take it out, and dry it to obtain a corrosion-resistant metal elbow for petrochemical use.

[0019] Embodiment 3: A method for preparing a corrosion-resistant metal elbow for petrochemical use, comprising the following steps: Step 1: Preparation of metal elbow: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1600℃ to melt, then cast them, cool them into shape, cut them and grind them to get the metal elbow; The metal elbow comprises the following components, calculated by mass percentage: 22wt% chromium, 7wt% nickel, 2.6wt% silicon, 1wt% manganese, 0.5wt% carbon, 0.4wt% vanadium, 0.2wt% magnesium, 0.03wt% cerium, 0.05wt% phosphorus, and the balance is iron; Step 2: Preparation of zeolite imidazole framework material: Take 0.52g 2-methylimidazole, 0.85g zinc nitrate hexahydrate, and 50mL methanol, stir for 2h, then stand for 26h, centrifuge, filter, wash, and dry to obtain a zeolite imidazole framework material; Step 3: Preparation of polyethyleneimine grafted with glycine: Take 0.8g of glycine, 1g of branched polyethyleneimine, and 30mL of deionized water, stir evenly, add 16µL of tert-butyl hydroperoxide dropwise, and react at 85°C under inert gas protection for 5h, remove the solvent by distillation under reduced pressure, add 80mL of anhydrous methanol, stir evenly, then add 10mL of 10% hydrochloric acid aqueous solution, precipitate, centrifuge, dry, add 100mL of deionized water, stir evenly, add sodium carbonate, adjust the pH value to 8.0, then dialyze with deionized water, freeze, and dry to obtain polyethyleneimine grafted with glycine; Step 4: Preparation of modified zeolite imidazole framework material: Take 2.5 g of zeolite imidazole framework material and 300 mL of deionized water, stir evenly, add 1 g of polyethyleneimine grafted with glycine, stir for 8 h, filter and dry to obtain a modified zeolite imidazole framework material; The mass ratio of zeolite imidazole framework material, polyethyleneimine grafted with glycine, and deionized water is: 2.5:1:300; Step 5: Preparation of pretreated nano zinc oxide: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take 100mL dopamine solution, add 5g nano zinc oxide, heat to 65°C, stir for 9h, filter, wash, and dry to obtain pretreated nano zinc oxide; Step 6: Preparation of zeolite imidazole framework-zinc oxide composite material: Take 5g of pretreated nano zinc oxide and 100mL of anhydrous ethanol, stir evenly, add 1.2mL of n-dodecyl mercaptan dropwise, heat to 65°C, stir for 3h, add 1g of modified zeolite imidazole framework material, stir for 8h, filter, wash and dry to obtain a zeolite imidazole framework-zinc oxide composite material; Step 7: Preparation of corrosion-resistant metal elbows for petrochemical applications: Take a 10mmol / L tris(hydroxymethyl)aminomethane solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain a Tris-HCl buffer solution; dissolve dopamine hydrochloride in the Tris-HCl buffer solution to obtain a 2g / L dopamine solution; take a metal elbow, wash it, dry it, and then immerse it in the dopamine solution for 2h, add a Tris-HCl solution containing 1.5g / L zeolite imidazole framework-zinc oxide composite material with an equal volume to the dopamine solution, continue to immerse for 6h, take it out, dry it, and obtain a corrosion-resistant metal elbow for petrochemical use.

[0020] Comparative Example 1: No glycine was grafted, and the rest was the same as Example 1: Step 1: Preparation of metal elbow: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1570℃ to melt, then cast them, cool them into shape, cut them and grind them to get the metal elbow; The metal elbow comprises the following components, calculated by mass percentage: 21wt% chromium, 7.5wt% nickel, 2.0wt% silicon, 0.7wt% manganese, 0.4wt% carbon, 0.3wt% vanadium, 0.15wt% magnesium, 0.02wt% cerium, 0.04% phosphorus, and the balance is iron; Step 2: Preparation of zeolite imidazole framework material: Take 0.52g 2-methylimidazole, 0.85g zinc nitrate hexahydrate, and 50mL methanol, stir for 1.5h, then stand for 25h, centrifuge, filter, wash, and dry to obtain a zeolite imidazole framework material; Step 3: Preparation of modified zeolite imidazole framework material: Take 2.2 g of zeolite imidazole framework material and 300 mL of deionized water, stir evenly, add 1 g of branched polyethyleneimine, stir for 7 h, filter and dry to obtain a modified zeolite imidazole framework material; The mass ratio of zeolite imidazole framework material, branched polyethyleneimine, and deionized water is: 2.2:1:300; Step 4: Preparation of pretreated nano zinc oxide: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take 100mL dopamine solution, add 5g nano zinc oxide, heat to 63°C, stir for 8h, filter, wash, and dry to obtain pretreated nano zinc oxide; Step 5: Preparation of zeolite imidazole framework-zinc oxide composite material: Take 5g of pretreated nano zinc oxide and 100mL of anhydrous ethanol, stir evenly, add 1.2mL of n-dodecyl mercaptan dropwise, heat to 63°C, stir for 2.5h, add 1g of modified zeolite imidazole framework material, stir for 7h, filter, wash and dry to obtain a zeolite imidazole framework-zinc oxide composite material; Step 6: Preparation of corrosion-resistant metal elbows for petrochemical applications: Take a 10mmol / L tris(hydroxymethyl)aminomethane solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain a Tris-HCl buffer solution; dissolve dopamine hydrochloride in the Tris-HCl buffer solution to obtain a 2g / L dopamine solution; take a metal elbow, wash it, dry it, and then immerse it in the dopamine solution for 1.5 hours, add a Tris-HCl solution containing 1.5g / L zeolite imidazole framework-zinc oxide composite material with an equal volume to the dopamine solution, continue to immerse for 5.5 hours, take it out, dry it, and obtain a corrosion-resistant metal elbow for petrochemical use.

[0021] Comparative Example 2: Polyethyleneimine without adding glycine, the rest is the same as Example 1: Step 1: Preparation of metal elbow: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1570℃ to melt, then cast them, cool them into shape, cut them and grind them to get the metal elbow; The metal elbow comprises the following components, calculated by mass percentage: 21wt% chromium, 7.5wt% nickel, 2.0wt% silicon, 0.7wt% manganese, 0.4wt% carbon, 0.3wt% vanadium, 0.15wt% magnesium, 0.02wt% cerium, 0.04% phosphorus, and the balance is iron; Step 2: Preparation of zeolite imidazole framework material: Take 0.52g 2-methylimidazole, 0.85g zinc nitrate hexahydrate, and 50mL methanol, stir for 1.5h, then stand for 25h, centrifuge, filter, wash, and dry to obtain a zeolite imidazole framework material; Step 3: Preparation of pretreated nano zinc oxide: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take 100mL dopamine solution, add 5g nano zinc oxide, heat to 63°C, stir for 8h, filter, wash, and dry to obtain pretreated nano zinc oxide; Step 4: Preparation of zeolite imidazole framework-zinc oxide composite material: Take 5g of pretreated nano zinc oxide and 100mL of anhydrous ethanol, stir evenly, add 1.2mL of n-dodecyl mercaptan dropwise, heat to 63°C, stir for 2.5h, add 1g of zeolite imidazole framework material, stir for 7h, filter, wash and dry to obtain a zeolite imidazole framework-zinc oxide composite material; Step 5: Preparation of corrosion-resistant metal elbows for petrochemical applications: Take a 10mmol / L tris(hydroxymethyl)aminomethane solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain a Tris-HCl buffer solution; dissolve dopamine hydrochloride in the Tris-HCl buffer solution to obtain a 2g / L dopamine solution; take a metal elbow, wash it, dry it, and then immerse it in the dopamine solution for 1.5 hours, add a Tris-HCl solution containing 1.5g / L zeolite imidazole framework-zinc oxide composite material with an equal volume to the dopamine solution, continue to immerse for 5.5 hours, take it out, dry it, and obtain a corrosion-resistant metal elbow for petrochemical use.

[0022] Comparative Example 3: The modified zeolite imidazole framework material and the nano zinc oxide are not compounded together, and the rest is the same as Example 1: Step 1: Preparation of metal elbow: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1570℃ to melt, then cast them, cool them into shape, cut them and grind them to get the metal elbow; The metal elbow comprises the following components, calculated by mass percentage: 21wt% chromium, 7.5wt% nickel, 2.0wt% silicon, 0.7wt% manganese, 0.4wt% carbon, 0.3wt% vanadium, 0.15wt% magnesium, 0.02wt% cerium, 0.04% phosphorus, and the balance is iron; Step 2: Preparation of zeolite imidazole framework material: Take 0.52g 2-methylimidazole, 0.85g zinc nitrate hexahydrate, and 50mL methanol, stir for 1.5h, then stand for 25h, centrifuge, filter, wash, and dry to obtain a zeolite imidazole framework material; Step 3: Preparation of polyethyleneimine grafted with glycine: Take 0.8g of glycine, 1g of branched polyethyleneimine, and 30mL of deionized water, stir evenly, add 16µL of tert-butyl hydroperoxide dropwise, and react at 83°C for 4h under the protection of inert gas. Remove the solvent by distillation under reduced pressure, add 80mL of anhydrous methanol, stir evenly, then add 10mL of 10% hydrochloric acid aqueous solution, precipitate, centrifuge, dry, add 100mL of deionized water, stir evenly, add sodium carbonate, adjust the pH value to 8.0, then dialyze with deionized water, freeze, and dry to obtain polyethyleneimine grafted with glycine; Step 4: Preparation of modified zeolite imidazole framework material: Take 2.2 g of zeolite imidazole framework material and 300 mL of deionized water, stir evenly, add 1 g of polyethyleneimine grafted with glycine, stir for 7 h, filter and dry to obtain a modified zeolite imidazole framework material; The mass ratio of zeolite imidazole framework material, polyethyleneimine grafted with glycine, and deionized water is: 2.2:1:300; Step 5: Preparation of pretreated nano zinc oxide: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take 100mL dopamine solution, add 5g nano zinc oxide, heat to 63°C, stir for 8h, filter, wash, and dry to obtain pretreated nano zinc oxide; Step 6: Preparation of corrosion-resistant metal elbows for petrochemical applications: Take 10mmol / L tris(hydroxymethyl)aminomethane) solution, add hydrochloric acid to adjust the pH value to 8.5, and obtain Tris-HCl buffer; dissolve dopamine hydrochloride in Tris-HCl buffer to obtain 2g / L dopamine solution; take a metal elbow, wash, dry, and then immerse it in the dopamine solution for 1.5h, add a Tris-HCl solution containing 1g / L modified zeolite imidazole framework material and 0.5g / L pretreated nano zinc oxide in an equal volume to the dopamine solution, continue immersing for 5.5h, take out, dry, and obtain a corrosion-resistant metal elbow for petrochemical use.

[0023] experiment: The corrosion-resistant metal elbows for petrochemical use prepared in Example 1-Example 3 and Comparative Example 1-Comparative Example 3 were tested for performance. The inner diameter of the metal elbow was 100 mm, the outer diameter was 105 mm, the curvature was 90°, and its yield strength was tested at 30°C. Referring to GB4334.7-84, a 6% concentration of ferric chloride solution was used to perform a pitting test on the metal elbow to test its corrosion rate. The data obtained are shown in the following table:

[0024] Conclusion: From the comparison of the data in the table, it can be seen that in Example 1, glycine is not grafted, and the deposition effect of the modified zeolite imidazole skeleton material on the surface of the metal elbow is poor, and the corrosion resistance is poor. In Example 2, polyethyleneimine without glycine is added. At this time, the corrosive medium is easily corroded and the corrosion resistance is reduced. In Example 3, the modified zeolite imidazole skeleton material is not compounded with nano zinc oxide. The modified zeolite imidazole skeleton material and nano zinc oxide have poor dispersibility and are easy to agglomerate, which affects the corrosion resistance of the metal elbow. The corrosion-resistant metal elbow for petrochemical use prepared by the present invention has high yield strength and good corrosion resistance.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a corrosion-resistant metal elbow for petrochemical use, characterized in that: The following steps are involved: Step 1: Take iron, chromium, nickel, silicon, manganese, carbon, vanadium, magnesium, cerium and phosphorus, mix them, heat them to 1550-1600℃ to melt, then cast them, cool them to form, cut and grind them to obtain a metal elbow; Step 2: Take the pretreated nano zinc oxide and anhydrous ethanol, stir evenly, add n-dodecyl mercaptan, heat to 60-65°C, stir for 2-3h, add modified zeolite imidazole framework material, stir for 6-8h, filter, wash and dry to obtain zeolite imidazole framework-zinc oxide composite material; Step 3: Take the metal elbow, clean it, dry it, and then immerse it in the dopamine solution for 1-2 hours, add the Tris-HCl solution containing the zeolite imidazole framework-zinc oxide composite material, continue to immerse it for 5-6 hours, take it out, dry it, and obtain a corrosion-resistant metal elbow for petrochemical use.

2. The method for preparing a corrosion-resistant metal elbow for petrochemical use according to claim 1, characterized in that: The preparation method of the modified zeolite imidazole framework material comprises the following steps: S1: Take glycine, branched polyethyleneimine, and deionized water, stir evenly, add tert-butyl hydroperoxide dropwise, reflux at 80-85°C for 3.5-5h under inert gas protection, remove the solvent by reduced pressure distillation, add anhydrous methanol, stir evenly, then add aqueous hydrochloric acid solution, precipitate, centrifuge, dry, add deionized water, stir evenly, add sodium carbonate, adjust the pH value to 8.0, then dialyze with deionized water, freeze, and dry to obtain polyethyleneimine grafted with glycine; S2: Take zeolite imidazole framework material and deionized water, stir evenly, add polyethyleneimine grafted with glycine, stir for 6-8 hours, filter and dry to obtain modified zeolite imidazole framework material.

3. The method for preparing a corrosion-resistant metal elbow for petrochemical use according to claim 2, characterized in that: The preparation method of the zeolite imidazole framework material is as follows: 2-methylimidazole, zinc nitrate hexahydrate and methanol are taken, stirred for 1-2 hours, then allowed to stand for 24-26 hours, centrifuged, filtered, washed and dried to obtain the zeolite imidazole framework material.

4. The method for preparing a corrosion-resistant metal elbow for petrochemical use according to claim 1, characterized in that: In step 2, the preparation method of the pretreated nano zinc oxide is as follows: taking a dopamine solution, adding nano zinc oxide, heating to 60-65° C., stirring for 7-9 hours, filtering, washing, and drying to obtain the pretreated nano zinc oxide.

5. The method for preparing a corrosion-resistant metal elbow for petrochemical use according to claim 1 or 4, characterized in that: The preparation method of the dopamine solution comprises: taking a tris(hydroxymethyl)aminomethane) solution, adding hydrochloric acid to adjust the pH value to 8.5, and obtaining a Tris-HCl buffer; and dissolving dopamine hydrochloride in the Tris-HCl buffer, and obtaining a dopamine solution.

6. The method for preparing a corrosion-resistant metal elbow for petrochemical use according to claim 1, characterized in that: The metal elbow includes the following components, calculated by mass percentage: 20wt%-22wt% of chromium, 7wt%-8wt% of nickel, 1.5wt%-2.6wt% of silicon, 0.5wt%-1wt% of manganese, 0.3wt%-0.5wt% of carbon, 0.2wt%-0.4wt% of vanadium, 0.1wt%-0.2wt% of magnesium, 0.01wt%-0.03wt% of cerium, 0.03wt%-0.05wt% of phosphorus, and the balance is iron.

7. The method for preparing a corrosion-resistant metal elbow for petrochemical use according to claim 2, characterized in that: In S2, the mass ratio of zeolite imidazole framework material, polyethyleneimine grafted with glycine, and deionized water is: (2-2.5): 1:

300.

8. A corrosion-resistant metal elbow for petrochemical use prepared according to the method for preparing a corrosion-resistant metal elbow for petrochemical use according to any one of claims 1 to 7.

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