Environment-friendly metal deactivator and preparation method thereof

Abstract

The invention discloses an environment-friendly metal deactivator and a preparation method thereof, and relates to the field of petrochemical engineering, and the environment-friendly metal deactivator comprises the following raw materials in parts by weight: 10-15 parts of modified nano magnesium oxide, 10-12 parts of citric acid, 20-25 parts of calcium nitrate and 350-450 parts of water. The modified nano magnesium oxide has strong hydrothermal stability, strong affinity with an FCC catalyst, strong capability of passivating heavy metals nickel and vanadium, effective inhibition of FCC catalyst poisoning, and high environmental protection property.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, specifically to an environmentally friendly metal passivating agent and its preparation method. Background Technology

[0002] Catalytic cracking (FCC) is one of the main processing technologies for lightening heavy oil. Currently, the FCC process faces significant challenges due to the increasing density and deterioration of crude oil. High levels of heavy metals (such as nickel and vanadium) in crude oil can lead to a significant increase in the content of these metals in the feedstock of the FCC unit. Nickel and vanadium in crude oil mainly exist as porphyrin compounds, which are relatively stable during the catalytic cracking reaction. However, they easily decompose and deposit on the catalyst during FCC catalyst regeneration, causing catalyst poisoning and reducing both activity and selectivity. To maintain high activity and long lifespan of FCC catalysts, metal passivators are commonly used industrially to inhibit the contamination of the catalyst by heavy metals such as nickel and vanadium.

[0003] The most widely used metal passivating agents currently include antimony-based nickel passivating agents and tin-based vanadium passivating agents. The passivation principle of antimony-based nickel passivating agents is to form an alloy between antimony and nickel, thereby inhibiting the strong dehydrogenation activity of Ni. 0 The formation of tin-based vanadium passivators aims to reduce the activity of deposited nickel, thereby decreasing the generation of hydrogen and coke. The passivation principle of tin-based vanadium passivators is to react tin with V₂O₅ in the feedstock oil to form high-melting-point compounds, inhibiting the migration of vanadium into the catalyst bulk phase or the formation of vanadate, thus avoiding vanadium's damage to the catalyst structure and reducing catalyst consumption. However, both antimony compounds and tin compounds are toxic substances and do not meet environmental protection requirements.

[0004] Previous studies have shown that, at temperatures below the FCC catalyst regeneration temperature (approximately 700°C), non-toxic magnesium salts react with V₂O₅ to form Mg₂V₂O₇, preventing V₂O₅ from damaging the crystal structure of the zeolite catalyst, thus achieving vanadium passivation. Because Mg… 2＋ and Ni 2＋ Lattice substitution occurs on the NiO crystal surface, causing Ni... 2＋ The significantly increased LUMO (lowest unoccupied orbital) energy in Ni indicates that it is more difficult for electrons to enter. 2＋ The more difficult it is to reduce, the lower the Ni value. 2＋ The reduction degree under FCC reaction conditions inhibits the strong dehydrogenation activity of low-valent nickel, achieving the purpose of passivating nickel. Nano-magnesium oxide, as a potential FCC metal passivating agent, meets environmental protection requirements, but its insufficient hydrothermal stability can lead to particle breakage and pulverization. Furthermore, nanoparticles tend to agglomerate into larger particles, resulting in a decrease in effective specific surface area, weakened interaction with heavy metals, and reduced passivation effect.

[0005] Therefore, suitable modification methods are needed to improve the hydrothermal stability of nano-magnesium oxide while reducing its agglomeration, in order to obtain a high-performance, environmentally friendly metal passivating agent. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an environmentally friendly metal passivating agent and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions: An environmentally friendly metal passivating agent comprises the following raw materials in parts by weight: 10-15 parts modified nano magnesium oxide, 10-12 parts citric acid, 20-25 parts calcium nitrate, and 350-450 parts water; The environmentally friendly metal passivating agent is prepared by the following steps: Citric acid was added to water, heated and stirred, then calcium nitrate was added and stirred again. Modified nano magnesium oxide was then added, and the mixture was ultrasonically dispersed. The remaining water was added, stirred, and the pH was adjusted to obtain an environmentally friendly metal passivating agent. The preparation of the environmentally friendly metal passivating agent includes the following specific steps: Add citric acid to 1 / 3 of the total volume of water, heat to 55-65℃, stir for 25-35 minutes, add calcium nitrate, continue stirring for 1-1.5 hours, add modified nano magnesium oxide, ultrasonically disperse for 40-50 minutes, add the remaining water, stir and adjust the pH to 6-6.5 to obtain an environmentally friendly metal passivating agent. The modified nano-magnesium oxide is prepared by the following steps: Step C1: Mix silane coupling agent a and ethanol solution, adjust pH with stirring, heat and reflux with stirring to obtain hydrolysate; dry and cool nano magnesium oxide, add it to ethanol solution and ultrasonically disperse, add hydrolysate, heat and reflux with stirring, filter, and vacuum dry to obtain product c1; Step C2: Mix sodium aminobenzenesulfonate, DMF, and ethanol, add tri-n-propylamine and product c1 while stirring, turn on reflux, heat and stir to obtain product c2; Step C3: After ultrasonic dispersion of nano-alumina and anhydrous ethanol, the mixture is dried to obtain pretreated nano-alumina; after ultrasonic dispersion of pretreated nano-alumina and methanol aqueous solution, the hydrolysate of silane coupling agent b is added, and the mixture is heated under reflux and stirred to obtain product c3. Step C4: After mixing and stirring products c2, c3, DMAC, and ethanol, 3-methoxypyridine is added and stirred under ultraviolet irradiation to obtain product c4; product c4 and DMF are mixed, sodium hydrosulfite is added while stirring, and heated and stirred to obtain product c5; product c5, triphosgene, and mixed solvent are mixed and stirred, reflux is turned on, protective gas is introduced, 2,3-dimethylpyridine and triethylamine are added, and after stirring, the temperature is raised and stirred to obtain modified nano magnesium oxide; The preparation of the modified nano-magnesium oxide includes the following specific steps: Step C1: Mix silane coupling agent a and ethanol solution, adjust pH to 4.5-5 with stirring, heat to 55-60℃, reflux and stir for 2-2.2h to obtain hydrolysate; dry nano magnesium oxide at 280-300℃ for 1-1.5h, cool and add to ethanol solution for ultrasonic dispersion for 15-20min, add hydrolysate, reflux and stir at 70-80℃ for 4-4.2h, filter, and vacuum dry at 55-60℃ to obtain product c1; Furthermore, the ratio of silane coupling agent a to ethanol solution in the hydrolysate is 22.5-23.5 g : 50-55 mL; silane coupling agent a is 2-(chloromethyl)allyltrimethoxysilane; the ratio of nano-magnesium oxide, ethanol solution, and hydrolysate is 10-12 g : 280-300 mL : 13-15 mL; the volume fraction of ethanol to water in the ethanol solution is 9-10 : 1; the volume fraction of ethanol is 95%. In step C1, the silane coupling agent a is hydrolyzed to modify the surface of the nano-magnesium oxide, resulting in nano-magnesium oxide with alkyl chloride and alkenyl groups on the surface, i.e., product c1. Step C2: Mix sodium aminobenzenesulfonate, DMF, and ethanol, stir for 35-45 min, add tri-n-propylamine and product c1, turn on reflux, and stir at 100-105℃ for 9-9.5 h to obtain product c2. Furthermore, the ratio of sodium aminobenzenesulfonate, DMF, ethanol, tri-n-propylamine, and product c1 is 25.5-26.5 g : 25-30 mL : 30-35 mL : 16-18 g : 19-21 g; the sodium aminobenzenesulfonate is 2-nitroaniline-4-sulfonate sodium salt; and the volume fraction of ethanol is 95%. In step C2, the amino group of sodium aminobenzenesulfonate reacts with the alkyl chloride of product C1 to undergo dehydrochlorination, yielding product C2, which contains alkenyl, nitro and sodium sulfonate on its surface. Step C3: Mix nano-alumina and anhydrous ethanol and ultrasonically disperse for 20-30 min, then dry at 105-110℃ for 2-2.5 h to obtain pretreated nano-alumina; mix pretreated nano-alumina and methanol aqueous solution and ultrasonically disperse for 35-40 min, add hydrolysate of silane coupling agent b, heat to 80-85℃, reflux and stir for 5-5.5 h to obtain product c3; Further, the ratio of nano-alumina to anhydrous ethanol is 1-1.5g:15-20mL; the ratio of pretreated nano-alumina, methanol aqueous solution, and hydrolysate of silane coupling agent b is 11-13g:210-230mL:18-20mL; the hydrolysate of silane coupling agent b is obtained by adding silane coupling agent b to methanol aqueous solution and stirring for 4-4.2h at pH 3.8-4.2 and temperature 28-32℃; the ratio of silane coupling agent b to methanol aqueous solution in the hydrolysate of silane coupling agent b is 21.5-22.5g:45-50mL; silane coupling agent b is mercaptopropyltrimethoxysilane; the volume ratio of methanol to water in the methanol aqueous solution is 3-3.5:1-1.2; In step C3, the silane coupling agent b is hydrolyzed and then used to modify the nano-alumina to obtain nano-alumina with thiol groups on the surface, i.e., product C3. Step C4: Mix and stir products c2, c3, DMAC, and ethanol for 35-45 min, add 3-methoxypyridine, and stir under UV irradiation for 30-35 min to obtain product c4; mix product c4 and DMF, add sodium hydrosulfite while stirring, heat to 50-55℃, and stir for 10-10.5 h to obtain product c5; mix and stir product c5, triphosgene, and mixed solvent for 3-3.5 h, turn on reflux, introduce protective gas, add 2,3-dimethylpyridine and triethylamine, stir for 1-1.5 h, heat to 75-80℃, and stir for 3-3.5 h to obtain modified nano-magnesium oxide; Further, the molar ratio of product c2, product c3, DMAC, ethanol, and 3-methoxypyridine is 12.5-13.5g: 20-22g: 200-220mL: 180-200mL: 5.5-6.5g; the UV light power is 50-100W; the volume fraction of ethanol is 95%; the molar ratio of product c4, DMF, and sodium hydrosulfite is 18-22g: 450-460mL: 25-27g; the molar ratio of product c5, triphosgene, mixed solvent, 2,3-dimethylpyridine, and triethylamine is 21-23g: 35-37g: 520-540mL: 7-9g: 10-12g; the mixed solvent is ethyl acetate and tetrahydrofuran mixed in a volume ratio of 1:1-1.5. In step C4, the alkenyl group of product C2 is grafted with the thiol group of product C3 to obtain product C4; the nitro group of product C4 is reduced to an amino group to obtain product C5; the amino group of product C5 reacts with triphosgene to obtain modified nano-magnesium oxide containing isocyanate groups. The beneficial effects of the present invention are as follows: The present invention discloses an environmentally friendly metal passivating agent and its preparation method. The metal passivating agent is prepared from raw materials such as modified nano magnesium oxide, citric acid, and calcium nitrate, and has strong environmental protection properties.

[0008] The modified nano-magnesium oxide is a product obtained by reacting nano-magnesium oxide modified with silane coupling agent a, nano-aluminum oxide modified with silane coupling agent b, sodium aminobenzenesulfonate, etc. By combining nano-magnesium oxide modified with silane coupling agent a and nano-alumina modified with silane coupling agent b, the aggregation phenomenon of both nano-magnesium oxide and nano-alumina is improved. This physically blocks water molecules from penetrating to the active sites of magnesium oxide, inhibiting its hydrolysis into magnesium hydroxide. Furthermore, the nano-alumina exhibits almost no hydrolysis at high temperatures and is chemically stable, resulting in modified nano-magnesium oxide with strong hydrothermal stability, thus compensating for the insufficient hydrothermal stability of nano-magnesium oxide. The use of sodium aminobenzenesulfonate salt further enhances the affinity between the modified nano-magnesium oxide and the FCC catalyst by forming isocyanate groups, thereby increasing the deposition rate of the metal passivator on the FCC catalyst and improving passivation ability. Sodium sulfonate salt ensures good solubility of the modified nano-magnesium oxide in water, and the sodium sulfonate groups can also form stable complexes with heavy metals such as nickel and vanadium, which is beneficial for inhibiting FCC catalyst poisoning. Therefore, the metal passivator of this invention has strong metal passivation ability. Detailed Implementation

[0009] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] Example 1 A modified nano-magnesium oxide, the preparation of which includes the following steps: Step C1: Mix 2-(chloromethyl)allyltrimethoxysilane and ethanol solution, adjust pH to 4.6 with stirring, heat to 58℃, and reflux for 2.1 h to obtain hydrolysate; dry nano-magnesium oxide (supplier: Shijiazhuang Jinghuang Technology Co., Ltd., packaging specification: 25kg) at 280℃ for 1 h, cool, add to ethanol solution and ultrasonically disperse for 15 min, add hydrolysate, reflux and stir at 70℃ for 4 h, filter, and vacuum dry at 55℃ to obtain product c1; the volume ratio of 2-(chloromethyl)allyltrimethoxysilane to ethanol solution in hydrolysate is 22.5g:50mL; the volume ratio of nano-magnesium oxide, ethanol solution, and hydrolysate is 10g:280mL:13mL; the volume fraction of ethanol to water in ethanol solution is 9:1; the volume fraction of ethanol is 95%; Step C2: Sodium 2-nitroaniline-4-sulfonate, DMF, and ethanol were mixed and stirred for 35 min. Tri-n-propylamine and product c1 were added, and reflux was started. The mixture was stirred at 100 °C for 9 h to obtain product c2. The ratio of sodium 2-nitroaniline-4-sulfonate, DMF, ethanol, tri-n-propylamine, and product c1 was 25.5 g: 25 mL: 30 mL: 16 g: 19 g; the volume fraction of ethanol was 95%. Step C3: Nano-alumina (Beijing Deco Island Gold Technology Co., Ltd., model: DK410-2) and anhydrous ethanol were mixed and ultrasonically dispersed for 20 min, then dried at 105℃ for 2 h to obtain pretreated nano-alumina. The pretreated nano-alumina and methanol aqueous solution were mixed and ultrasonically dispersed for 35 min, and the hydrolysate of silane coupling agent b was added. The mixture was heated to 80℃ and refluxed with stirring for 5 h to obtain product c3. The ratio of nano-alumina to anhydrous ethanol was 1 g:15 mL; the ratio of pretreated nano-alumina, methanol aqueous solution, and hydrolysate of silane coupling agent b was 11 g:210 mL:18 mL; the hydrolysate of silane coupling agent b was obtained by adding mercaptopropyltrimethoxysilane to methanol aqueous solution and stirring for 4 h at pH 3.9 and temperature 28℃; the ratio of mercaptopropyltrimethoxysilane to methanol aqueous solution in the hydrolysate of silane coupling agent b was 21.5 g:45 mL; the volume ratio of methanol to water in the methanol aqueous solution was 3:1. Step C4: Mix and stir products c2, c3, DMAC, and ethanol for 35 min, add 3-methoxypyridine, and stir under UV irradiation for 30 min to obtain product c4; mix product c4 and DMF, add sodium hydrosulfite while stirring, heat to 50℃, and stir for 10 h to obtain product c5; mix and stir product c5, triphosgene, and mixed solvent for 3 h, turn on reflux, introduce nitrogen gas, add 2,3-dimethylpyridine and triethylamine, stir for 1 h, heat to 75℃, and stir for 3 h to obtain modified nano-magnesium oxide; products c2, c3, and ethanol are mixed and stirred for 3 h. The ratio of c3, DMAC, ethanol, and 3-methoxypyridine was 12.5g:20g:200mL:180mL:5.5g; the UV light power was 50W; the volume fraction of ethanol was 95%; the ratio of product c4, DMF, and sodium hydrosulfite was 18g:450mL:25g; the ratio of product c5, triphosgene, mixed solvent, 2,3-dimethylpyridine, and triethylamine was 21g:35g:520mL:7g:10g; the mixed solvent was ethyl acetate and tetrahydrofuran mixed in a 1:1 volume ratio.

[0011] Example 2 A modified nano-magnesium oxide, the preparation of which includes the following steps: Step C1: Mix 2-(chloromethyl)allyltrimethoxysilane and ethanol solution, adjust pH to 4.8 with stirring, heat to 58℃, and reflux for 2.1 h to obtain hydrolysate; dry nano-magnesium oxide (supplier: Shijiazhuang Jinghuang Technology Co., Ltd., packaging specification: 25kg) at 290℃ for 1.3 h, cool, add to ethanol solution and ultrasonically disperse for 18 min, add hydrolysate, reflux for 4.1 h at 75℃, filter, and vacuum dry at 58℃ to obtain product c1; the volume ratio of 2-(chloromethyl)allyltrimethoxysilane to ethanol solution in hydrolysate is 23.0 g: 53 mL; the volume ratio of nano-magnesium oxide, ethanol solution, and hydrolysate is 11 g: 290 mL: 14 mL; the volume fraction of ethanol to water in ethanol solution is 9.5: 1; the volume fraction of ethanol is 95%; Step C2: Sodium 2-nitroaniline-4-sulfonate, DMF, and ethanol were mixed and stirred for 40 min. Tri-n-propylamine and product c1 were added, and reflux was started. The mixture was stirred at 103 °C for 9.3 h to obtain product c2. The ratio of sodium 2-nitroaniline-4-sulfonate, DMF, ethanol, tri-n-propylamine, and product c1 was 26.0 g: 28 mL: 33 mL: 17 g: 20 g; the volume fraction of ethanol was 95%. Step C3: Nano-alumina and anhydrous ethanol were ultrasonically dispersed for 25 min and dried at 108℃ for 2.3 h to obtain pretreated nano-alumina; the pretreated nano-alumina and methanol aqueous solution were ultrasonically dispersed for 38 min, and the hydrolysate of silane coupling agent b was added. The mixture was heated to 83℃ and refluxed with stirring for 5.3 h to obtain product c3; the ratio of nano-alumina to anhydrous ethanol was 1.3 g: 18 mL; the ratio of pretreated nano-alumina, methanol aqueous solution, and hydrolysate of silane coupling agent b was 12 g: 220 mL: 19 mL; the hydrolysate of silane coupling agent b was obtained by adding mercaptopropyltrimethoxysilane to methanol aqueous solution and stirring at pH 4.0 and temperature 30℃ for 4.1 h; the ratio of mercaptopropyltrimethoxysilane to methanol aqueous solution in the hydrolysate of silane coupling agent b was 22.0 g: 48 mL; the volume ratio of methanol to water in the methanol aqueous solution was 3.2: 1.1; Step C4: Mix and stir products C2, C3, DMAC, and ethanol for 40 min, add 3-methoxypyridine, and stir under UV irradiation for 33 min to obtain product C4; mix product C4 and DMF, add sodium hydrosulfite while stirring, heat to 53℃, and stir for 10.3 h to obtain product C5; mix and stir product C5, triphosgene, and mixed solvent for 3.3 h, turn on reflux, introduce protective gas, add 2,3-dimethylpyridine and triethylamine, stir for 1.3 h, heat to 78℃, and stir for 3.3 h to obtain modified nano-magnesium oxide; product The molar ratios of c2, c3, DMAC, ethanol, and 3-methoxypyridine were 13.0 g: 21 g: 210 mL: 19 mL: 6.0 g; the UV light power was 50 W; and the volume fraction of ethanol was 95%. The molar ratios of c4, DMF, and sodium hydrosulfite were 20 g: 455 mL: 26 g. The molar ratios of c5, triphosgene, mixed solvent, 2,3-dimethylpyridine, and triethylamine were 22 g: 36 g: 530 mL: 8 g: 11 g; and the mixed solvent was a mixture of ethyl acetate and tetrahydrofuran in a volume ratio of 1:1.3.

[0012] Example 3 A modified nano-magnesium oxide, the preparation of which includes the following steps: Step C1: Mix 2-(chloromethyl)allyltrimethoxysilane and ethanol solution, adjust pH to 4.9 with stirring, heat to 60℃, and reflux for 2.2h to obtain hydrolysate; dry nano-magnesium oxide (supplier: Shijiazhuang Jinghuang Technology Co., Ltd., packaging specification: 25kg) at 300℃ for 1.5h, cool, add to ethanol solution and ultrasonically disperse for 20min, add hydrolysate, reflux for 4.2h at 80℃, filter, and vacuum dry at 60℃ to obtain product c1; the volume ratio of 2-(chloromethyl)allyltrimethoxysilane to ethanol solution in hydrolysate is 23.5g:55mL; the volume ratio of nano-magnesium oxide, ethanol solution, and hydrolysate is 12g:300mL:15mL; the volume fraction of ethanol to water in ethanol solution is 10:1; the volume fraction of ethanol is 95%; Step C2: Sodium 2-nitroaniline-4-sulfonate, DMF, and ethanol were mixed and stirred for 45 min. Tri-n-propylamine and product c1 were added, and reflux was started. The mixture was stirred at 105 °C for 9.5 h to obtain product c2. The ratio of sodium 2-nitroaniline-4-sulfonate, DMF, ethanol, tri-n-propylamine, and product c1 was 26.5 g: 30 mL: 35 mL: 18 g: 21 g; the volume fraction of ethanol was 95%. Step C3: Nano-alumina and anhydrous ethanol were mixed and ultrasonically dispersed for 30 min, then dried at 110℃ for 2.5 h to obtain pretreated nano-alumina. The pretreated nano-alumina and methanol aqueous solution were mixed and ultrasonically dispersed for 40 min, and the hydrolysate of silane coupling agent b was added. The mixture was heated to 85℃ and refluxed with stirring for 5.5 h to obtain product C3. The ratio of nano-alumina to anhydrous ethanol was 1.5 g: 20 mL. The ratio of pretreated nano-alumina, methanol aqueous solution, and hydrolysate of silane coupling agent b was 13 g: 230 mL: 20 mL. The hydrolysate of silane coupling agent b was obtained by adding mercaptopropyltrimethoxysilane to methanol aqueous solution and stirring at pH 4.2 and temperature 32℃ for 4.2 h. The ratio of mercaptopropyltrimethoxysilane to methanol aqueous solution in the hydrolysate of silane coupling agent b was 22.5 g: 45-50 mL. The volume ratio of methanol to water in the methanol aqueous solution was 3.5: 1.2. Step C4: Mix and stir products C2, C3, DMAC, and ethanol for 45 min, add 3-methoxypyridine, and stir under UV irradiation for 35 min to obtain product C4; mix product C4 and DMF, add sodium hydrosulfite while stirring, heat to 55℃, and stir for 10.5 h to obtain product C5; mix and stir product C5, triphosgene, and mixed solvent for 3.5 h, turn on reflux, introduce protective gas, add 2,3-dimethylpyridine and triethylamine, stir for 1.5 h, heat to 80℃, and stir for 3.5 h to obtain modified nano-magnesium oxide; product C 2. The ratio of product c3, DMAC, ethanol, and 3-methoxypyridine was 13.5g:22g:220mL:200mL:6.5g; the UV light power was 50W; the volume fraction of ethanol was 95%; the ratio of product c4, DMF, and sodium hydrosulfite was 22g:460mL:27g; the ratio of product c5, triphosgene, mixed solvent, 2,3-dimethylpyridine, and triethylamine was 23g:37g:540mL:9g:12g; the mixed solvent was ethyl acetate and tetrahydrofuran mixed in a volume ratio of 1:1.5.

[0013] Example 4 An environmentally friendly metal passivating agent comprises the following raw materials in parts by weight: 10 parts modified nano magnesium oxide, 10 parts citric acid, 20 parts calcium nitrate, and 350 parts water; The environmentally friendly metal passivating agent is prepared by the following steps: Citric acid was added to water accounting for 1 / 3 of the total volume, the temperature was raised to 55°C, and the mixture was stirred for 25 minutes. Calcium nitrate was added, and the mixture was stirred for another 1 hour. The modified nano-magnesium oxide obtained in Example 1 was added, and the mixture was ultrasonically dispersed for 40 minutes. The remaining water was added, and the mixture was stirred and the pH was adjusted to 6.1 to obtain an environmentally friendly metal passivating agent.

[0014] Example 5 An environmentally friendly metal passivating agent comprises the following raw materials in parts by weight: 13 parts modified nano magnesium oxide, 11 parts citric acid, 23 parts calcium nitrate, and 400 parts water; The environmentally friendly metal passivating agent is prepared by the following steps: Citric acid was added to 1 / 3 of the total volume of water, heated to 60°C, stirred for 30 min, calcium nitrate was added, and stirring was continued for 1.3 h. Modified nano magnesium oxide obtained in Example 2 was added, ultrasonically dispersed for 45 min, the remaining water was added, stirred and the pH was adjusted to 6.3 to obtain an environmentally friendly metal passivating agent.

[0015] Example 6 An environmentally friendly metal passivating agent comprises the following raw materials in parts by weight: 15 parts modified nano magnesium oxide, 12 parts citric acid, 25 parts calcium nitrate, and 450 parts water; The environmentally friendly metal passivating agent is prepared by the following steps: Citric acid was added to 1 / 3 of the total volume of water, heated to 65°C, stirred for 35 minutes, calcium nitrate was added, and stirring was continued for 1.5 hours. The modified nano magnesium oxide obtained in Example 3 was added, and ultrasonic dispersion was carried out for 50 minutes. The remaining water was added, stirred, and the pH was adjusted to 6.5 to obtain an environmentally friendly metal passivating agent.

[0016] Comparative Example 1 Compared with Example 6, the nano-alumina used in the preparation process of modified nano-magnesium oxide used as the metal passivator was replaced with nano-silicon oxide, while the rest was exactly the same as in Example 6, thus obtaining an environmentally friendly metal passivator.

[0017] Comparative Example 2 Compared with Example 6, the modified nano-magnesium oxide used in the metal passivator was replaced with product c5, and the rest was exactly the same as in Example 6, thus obtaining an environmentally friendly metal passivator.

[0018] The metal passivating agent prepared in this invention was further tested for its effectiveness, and the test results are as follows.

[0019] 20g of RICC-3 catalyst was calcined at 350℃ for 4h; then, nickel naphthenate and vanadium naphthenate were dissolved in petroleum ether and impregnated with the calcined catalyst using the Mitchell artificial impregnation method to achieve nickel and vanadium contents of 6g / L and 3g / L, respectively. The impregnated catalyst was then calcined at 550℃ for 3h, followed by hydrothermal treatment at 700℃ and 100% steam for 4h to obtain a blank catalyst, which served as a blank control group. 20g of the blank catalyst was then impregnated with 40g of the environmentally friendly metal passivating agent obtained in Examples 4-6 and Comparative Examples 1-2 of this invention. After impregnation for 40min, the catalyst was removed and subjected to hydrothermal treatment at 750℃ and 100% steam for 4h to obtain the passivated catalysts obtained in Examples 4-6 and Comparative Examples 1-2 of this invention. Referring to NB / SH / T0952-2017, a light oil micro-reaction experiment was conducted. The experimental conditions were as follows: the feed oil was a straight-run light diesel oil fraction at 235-337℃, the reaction pressure was 0.1MPa, the reaction temperature was 460℃, the feed oil rate was 1.56g, the catalyst loading was 5g, the catalyst-to-oil mass ratio was 3.2, and the purge gas after the reaction was nitrogen with a flow rate of 30mL / min. The experimental method was as follows: the reactor and product receiver were thoroughly cleaned with acetone and dried. Quartz sand was filled into the bottom 20mm of the reactor. Then, 5g of catalyst was added to the reactor in a free-flowing manner, ensuring that it was loaded into the middle section of the reactor. The reactor was gently tapped to ensure good catalyst distribution. The reactor was inserted into the heating furnace, and the nitrogen purge line and reactor feed line were connected. The nitrogen purge gas flow rate was 30mL / min, and the purge time was 30min. The oil pump was turned on, the oil output rate was calibrated, the empty weight of the receiver was weighed, and it was placed at the bottom of the reactor and placed in an ice-water bath. Close the nitrogen valve and wait for the temperature to rise to 460℃ before starting the feed. The feed time is 75 seconds, and the feed rate is 1.56 g. After feeding is complete, open the nitrogen valve and purge the reactor at a gas flow rate of 30 mL / min for 15 minutes to ensure that the product completely enters the liquid receiver. Finally, remove the product receiver from the reactor, seal it quickly, wipe it dry, and weigh it. The composition analysis of the product was determined according to ASTM D7964 method, and the results are recorded in Table 1. The results are recorded in Table 1; Table 1: Test Results According to the data in Table 1, the metal passivator of the present invention has strong metal passivation ability, effectively inhibits FCC catalyst poisoning, improves the conversion rate and gasoline / diesel yield of the catalytic cracking reaction in the FCC process, and reduces the yield of hydrogen and coke. Comparing Example 6 with Comparative Example 1, it can be seen that replacing the nano-alumina in the preparation process of the modified nano-magnesium oxide used in the metal passivator preparation with nano-silicon oxide reduces the ability to improve the hydrothermal stability of the modified nano-magnesium oxide, decreases the passivation ability of the resulting metal passivator for heavy metals, reduces the ability to inhibit catalyst poisoning, and decreases both the conversion rate and gasoline / diesel yield of the catalytic cracking reaction, while increasing the yield of hydrogen and coke. Comparing Example 6 with Comparative Example 2, it can be seen that replacing the modified nano-magnesium oxide used in the preparation of the metal passivator with product C5 reduces the affinity with the FCC catalyst, weakens the passivation ability, decreases both the conversion rate and gasoline / diesel yield of the catalytic cracking reaction, and increases the yield of hydrogen and coke.

[0020] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. An environmentally friendly metal passivating agent, characterized in that: The raw materials include the following parts by weight: 10-15 parts modified nano magnesium oxide, 10-12 parts citric acid, 20-25 parts calcium nitrate, and 350-450 parts water; The modified nano-magnesium oxide is prepared by the following steps: Step C1: Mix silane coupling agent a and ethanol solution, adjust pH with stirring, heat and reflux with stirring to obtain hydrolysate; dry and cool nano magnesium oxide, add it to ethanol solution and ultrasonically disperse, add hydrolysate, heat and reflux with stirring, filter, and vacuum dry to obtain product c1; Step C2: Mix sodium aminobenzenesulfonate, DMF, and ethanol, add tri-n-propylamine and product c1 while stirring, turn on reflux, heat and stir to obtain product c2; Step C3: After ultrasonic dispersion of nano-alumina and anhydrous ethanol, the mixture is dried to obtain pretreated nano-alumina; after ultrasonic dispersion of pretreated nano-alumina and methanol aqueous solution, the hydrolysate of silane coupling agent b is added, and the mixture is heated under reflux and stirred to obtain product c3. Step C4: After mixing and stirring products c2, c3, DMAC, and ethanol, 3-methoxypyridine is added, and the mixture is stirred under ultraviolet irradiation to obtain product c4; product c4 and DMF are mixed, sodium hydrosulfite is added while stirring, and the mixture is heated and stirred to obtain product c5; product c5, triphosgene, and mixed solvent are mixed and stirred, reflux is turned on, protective gas is introduced, 2,3-dimethylpyridine and triethylamine are added, and the mixture is stirred and heated to obtain modified nano-magnesium oxide.

2. The environmentally friendly metal passivating agent according to claim 1, characterized in that: In step C1, the silane coupling agent a is 2-(chloromethyl)allyltrimethoxysilane.

3. The environmentally friendly metal passivating agent according to claim 1, characterized in that: In step C2, the sodium aminobenzenesulfonate is sodium 2-nitroaniline-4-sulfonate.

4. The environmentally friendly metal passivating agent according to claim 1, characterized in that: In step C3, the hydrolysate of silane coupling agent b is obtained by adding silane coupling agent b to an aqueous methanol solution and stirring for 4-4.2 hours at a pH of 3.8-4.2 and a temperature of 28-32°C.

5. The environmentally friendly metal passivating agent according to claim 1, characterized in that: In step C4, the mixed solvent is obtained by mixing ethyl acetate and tetrahydrofuran in a volume ratio of 1:1-1.

5.

6. The environmentally friendly metal passivating agent according to claim 4, characterized in that: Silane coupling agent b is mercaptopropyltrimethoxysilane.

7. A method for preparing an environmentally friendly metal passivating agent according to any one of claims 1-6, characterized in that: The process includes the following steps: mixing citric acid and water, heating and stirring, adding calcium nitrate, continuing to stir, adding modified nano-magnesium oxide, ultrasonically dispersing, adding water, stirring and adjusting the pH to obtain an environmentally friendly metal passivating agent.

8. The method for preparing an environmentally friendly metal passivating agent according to claim 7, characterized in that: The mass ratio of water added in the two additions was 1:2; the pH was adjusted to 6-6.5.

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