A composite anti-coking and anti-scaling agent for S-Zorb adsorptive desulfurization device and a preparation method thereof

Abstract

This invention relates to process aids technology for catalytic cracking gasoline adsorption desulfurization (S-Zorb) units in the petroleum refining field, specifically disclosing a composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units and its preparation method. The composite anti-coking and scale inhibitor comprises, by weight: 15-25 parts of a temperature-responsive nanoporous silica-supported composite antioxidant and polymerization inhibitor, 2-5 parts of a free antioxidant and polymerization inhibitor, 2-5 parts of a benzotriazole-type metal passivator, 4-8 parts of a self-healing film-forming agent containing siloxane groups, 2-4 parts of an oil-soluble imidazoline corrosion inhibitor, 10-15 parts of a polyisobutylene succinimide dispersant, 6-10 parts of a Mannich base-type detergent, and 28-59 parts of a high-boiling-point aromatic solvent oil. The anti-coking and scale inhibitor of this invention constructs a multi-component synergistic protection system of "antioxidant-passivation-film formation-dispersion-determination-corrosion inhibition," possessing both intelligent slow-release and self-healing film-forming functions, and exhibiting excellent high-temperature anti-coking and scale inhibition performance.

Description

Technical Field

[0001] This invention relates to process aid technology for catalytic cracking gasoline adsorption desulfurization (S-Zorb) units in the petroleum refining field, specifically to a composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units and its preparation method. Background Technology

[0002] The S-Zorb process is a catalytic cracking gasoline adsorption desulfurization technology introduced and assimilated by Sinopec. This technology is one of the key technologies for producing clean gasoline meeting the China VI standard. The feedstock heat exchangers in an S-Zorb adsorption desulfurization unit typically consist of 3-4 sets of heat exchangers connected in series, either in a single or double row. The primary or secondary heat exchangers are generally made of carbon steel. The feedstock catalytic gasoline contains a high sulfur content (500-800 μg / g), gum, and small amounts of dienes (dien value 1.5-2.5 gI2 / 100g), olefins (25-30 v%), catalyst powder, and metal compounds. Therefore, the low-temperature section of the feedstock heat exchanger pipeline is prone to corrosion, generating ferrous sulfide (FeS), while the medium- and high-temperature sections are prone to coking.

[0003] As catalytic cracking gasoline flows from a low temperature to a high temperature, a phase change occurs, transforming it from a liquid to a gaseous state. This makes it easier for polymers and other colloids, FeS detached from the front end, catalyst powder, and metal compounds to precipitate and deposit on the equipment surface. This reduces the heat transfer coefficient, increases pressure drop, and increases energy consumption. Severe scaling can cause blockages, forcing the unit to shut down.

[0004] Currently, there are some technical solutions for anti-coking and scale inhibitors for S-Zorb units.

[0005] CN108342221B discloses an anti-coking and scale inhibitor for S-Zorb devices, comprising a free radical scavenger, a detergent-dispersant (polyisobutylene Mannich base or polyisobutylene amine), an antioxidant (screening phenols), and an organic solvent. This patented technology does not contain metal ions, but it only works through free radical scavenging and detergent-dispersing mechanisms, resulting in a single function. Its antioxidant effect is significantly reduced under high-temperature conditions above 300°C, and its scale inhibition cycle is relatively short.

[0006] CN104845673A discloses an anti-coking and scale inhibitor for S-Zorb devices, comprising an antioxidant and polymerization inhibitor (sec-octylphenol), a metal passivator (aminotriazole), a detergent and dispersant (polyisobutylene diimide), a film-forming agent (oil-soluble imidazoline), and a solvent. This technology introduces metal passivation and film-forming functions. However, aminotriazole-based metal passivators have insufficient thermal stability above 350°C and are prone to decomposition and failure. Furthermore, the oil-soluble imidazoline film-forming agent only forms a physical adsorption film on the metal surface, resulting in poor erosion resistance.

[0007] CN114686264B discloses a coking and scale inhibitor for S-Zorb devices, characterized by comprising the following raw materials in parts by weight: 12-17 parts antioxidant, 7-11 parts hydroxylamine polymerization inhibitor, 6-9 parts polyisobutylene diimide, 7-9 parts iminodisuccinate, 4-6 parts viscosity modifier, 5-8 parts modified activated carbon, 7-10 parts ammonium persulfate, 5-7 parts oil-soluble imidazoline, and 53-74 parts No. 120 solvent oil. However, its composition is complex, with significant antagonistic effects between the components. Furthermore, the modified activated carbon is easily worn away in the flowing medium, limiting its slow-release performance. Crucially, the preparation process introduces additional iron and moisture. Ammonium persulfate decomposes and releases oxygen, which is strictly controlled for oxygen in adsorption desulfurization devices, requiring extreme caution in introducing additional oxygen. Additionally, iron, moisture, and oxygen all promote polymerization and coking, which is detrimental to coking and scale prevention. Therefore, this technology has significant shortcomings.

[0008] CN102732286B discloses a compound containing polyolefin succinimide and thiophosphate generated by the Mannich reaction as an anti-coking and scale inhibitor, which has a good cleaning and dispersing effect. However, it essentially only provides a dispersant and does not involve anti-coking and scale inhibition of the S-Zorb device.

[0009] In summary, the existing S-Zorb device anti-coking and scale inhibitor technology still has the following shortcomings: (1) Single function, most of them only have the function of dispersion or anti-oxidation, which is difficult to deal with the multi-path causes of coking; (2) The film-forming components have weak bonding force with the metal surface, and the control of carbon steel corrosion in the low temperature range is limited. Although the existing technology proposes to use imidazoline corrosion inhibitors, the imidazoline adsorption film has poor erosion resistance, cannot achieve long-term protection, and does not have self-repair function; (3) Anti-oxidation and polymerization inhibitor components are consumed in large quantities in the low and medium temperature range, which cannot achieve "delayed protection", thus lacking effective protection in the high temperature range; (4) Insufficient high temperature stability, some components of the existing technology decompose at low temperatures.

[0010] Therefore, there is an urgent need to develop a new type of S-Zorb device anti-coking and scale inhibitor that combines high-temperature oxidation resistance, temperature-responsive intelligent release, long-lasting metal passivation and corrosion inhibition, and self-healing film formation functions. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization devices and its preparation method. The composite anti-coking and scale inhibitor constructs an eight-component synergistic protection system of "antioxidant-passivation-film formation-dispersion-cleaning-corrosion inhibition" by introducing a temperature-responsive nanoporous silica-supported composite antioxidant and a self-healing film-forming agent containing siloxane groups. In particular, the temperature-responsive controlled-release technology of the basic magnesium carbonate coating layer achieves "precise on-demand release" of the active components, while the self-healing chemical film formation provides long-term protection, enabling long-term and precise anti-coking and scale inhibition under the high-temperature operating conditions of the S-Zorb device.

[0012] The present invention achieves the above objectives through the following technical solutions:

[0013] A composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units, comprising the following components by weight:

[0014] 15-25 parts of temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor;

[0015] 2-5 parts of free antioxidant polymerization inhibitor;

[0016] 2-5 parts of benzotriazole-type metal passivating agent;

[0017] 4-8 parts of a self-healing film-forming agent containing siloxane groups;

[0018] 2-4 parts of oil-soluble imidazoline corrosion inhibitor;

[0019] 10-15 parts of polyisobutylene succinimide dispersant;

[0020] 6-10 parts of Mannich base-type detergent;

[0021] 28-59 parts of high-boiling-point aromatic solvent oil.

[0022] Preferably, the preparation method of the temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor includes the following steps:

[0023] (1) First, the carrier is vacuum dried at 120℃ for 4h, cooled to room temperature, and then the free antioxidant polymerization inhibitor is dissolved in anhydrous ethanol to obtain a mixed solution with a mass concentration of 20-30%; then the dried carrier is immersed in the above mixed solution, stirred and immersed at room temperature for 12h, and finally vacuum dried at 80℃ for 6h to obtain mesoporous silica loaded with composite antioxidant; wherein, the carrier is MCM-41 type or SBA-15 type mesoporous silica, the pore size of the carrier is 6-10nm, the specific surface area is 800-1200m² / g, and the particle size is 50-100nm;

[0024] (2) First, basic magnesium carbonate (4MgCO3·Mg(OH)2·nH2O) is dispersed in deionized water, and an oil-soluble surfactant (such as Span-80) is added to obtain a 5-10% basic magnesium carbonate suspension; then, the mesoporous silica loaded with composite antioxidant obtained in step (1) is dispersed in the above basic magnesium carbonate suspension, stirred at 60-80℃ for 2-3 hours, and finally filtered and vacuum dried at 80℃ for 4 hours to obtain a temperature-responsive nano-mesoporous silica loaded with composite antioxidant polymerization inhibitor; wherein, the mass of the oil-soluble surfactant is 1.5-3% of the mass of basic magnesium carbonate.

[0025] Preferably, the free antioxidant polymerization inhibitor is obtained by compounding hindered phenolic antioxidants and aromatic amine antioxidants, and the mass ratio of hindered phenolic antioxidants to aromatic amine antioxidants is 1:0.5 to 1:2.

[0026] Preferably, the hindered phenolic antioxidant is selected from 2,6-di-tert-butyl-4-methylphenol (BHT) and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester (1076), and the aromatic amine antioxidant is selected from N-phenyl-α-naphthylamine (antioxidant A) and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

[0027] Preferably, the benzotriazole-type metal passivating agent is N-di(2-ethylhexyl)aminomethyl-methylbenzotriazole (T551).

[0028] Preferably, the preparation method of the self-healing film-forming agent containing siloxane groups is as follows: aminopropyltriethoxysilane and 4-boronicobenzoic acid are mixed at a molar ratio of 1:1.0 to 1.2, and reacted at 140 to 160°C for 4 to 6 hours under nitrogen protection. Water and low-boiling substances are removed by vacuum distillation to generate a silane coupling agent containing borate ester dynamic covalent bonds, thereby obtaining the self-healing film-forming agent containing siloxane groups.

[0029] Preferably, the oil-soluble imidazoline corrosion inhibitor is selected from oleic acid imidazoline and / or naphthenic acid imidazoline.

[0030] Preferably, the polyisobutylene succinimide dispersant is selected from monoalkenyl succinimide and / or diene succinimide, with a number average molecular weight of 1000 to 2400.

[0031] Preferably, the Mannich base-type detergent is a polyisobutylene Mannich base, which is prepared by a Mannich reaction of highly active polyisobutylene with a number average molecular weight of 1000, polyethylene polyamine and formaldehyde.

[0032] Preferably, the composite anti-scorching and scale inhibitor and its preparation method are as follows:

[0033] High-boiling-point aromatic solvent oil (SA-1500, SA-1800 or SA-2000) is added to a reaction vessel and heated to 50-60℃. Under stirring conditions, benzotriazole-type metal passivator, free antioxidant polymerization inhibitor, prepared temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor, polyisobutylene succinimide dispersant, prepared self-healing film-forming agent, Mannich base detergent and oil-soluble imidazoline corrosion inhibitor are added sequentially. Stirring is continued for 1-2 hours until all components are uniformly dispersed to obtain a composite anti-coking and scale inhibitor for use in S-Zorb adsorption desulfurization units.

[0034] Beneficial effects of the present invention

[0035] Compared with the prior art, the present invention has the following significant advantages:

[0036] (1) This invention creatively uses a temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor, utilizing a basic magnesium carbonate coating layer to densely block the mesoporous channels at low temperatures. The thermal decomposition of basic magnesium carbonate occurs in two stages: the first stage (142–302°C, DTG peak 236°C) and the second stage (306–483°C, DTG peak 458°C). When the mesoporous silica-supported composite antioxidant polymerization inhibitor enters the tube side of the 2nd to 3rd stage (medium temperature section) of the heat exchanger, the medium temperature range is exactly within the first stage of the thermal decomposition of basic magnesium carbonate. At this time, basic magnesium carbonate loses its water of crystallization, shrinks in volume to produce cracks and pores, the mesoporous channels open, and the antioxidant active components begin to be released. When the mesoporous silica-loaded composite antioxidant polymerization inhibitor enters the tube side of the 3rd to 4th stage (high temperature section) of the heat exchanger, the thermal decomposition of basic magnesium carbonate reaches the second stage (temperature above 300℃), decomposing into MgO, CO2 and H2O, and the antioxidant active components are completely released, achieving "precise on-demand protection" in the medium and high temperature sections.

[0037] (2) Temperature-responsive nanoporous silica-supported composite antioxidant and polymerization inhibitor combined with free antioxidant and polymerization inhibitor achieves "instant + delayed" dual antioxidant defense line, enabling the heat exchanger to achieve effective antioxidant and polymerization inhibition protection from low temperature to high temperature, avoiding the problem of antioxidant and polymerization inhibitor being consumed in large quantities in the low temperature range and having no effective protection in the high temperature range.

[0038] (3) This invention creatively introduces a self-healing film-forming agent technology containing siloxane groups, which can form an organic-inorganic hybrid protective film with BO-Fe coordination bonds and Si-O-Fe covalent bonds on the metal surface. Compared with the physical adsorption film of the prior art, the bonding strength is increased by more than 3 times and the erosion resistance is significantly enhanced. It also has a self-healing function. When the film is locally damaged, the "latent" siloxane groups and the dynamic covalent bonds of borate esters can continue to hydrolyze and condense to achieve automatic repair, ensuring long-term protection. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the performance testing process for the present invention. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0041] Example 1

[0042] A composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units, comprising the following components by weight:

[0043] Temperature-responsive nanoporous silica (MCM-41) supported composite antioxidant polymerization inhibitor 18 Free antioxidant polymerization inhibitor (BHT to antioxidant A mass ratio of 1:1) 5 N-Di(2-ethylhexyl)aminomethyl-methylbenzotriazole (T551) 5 Self-healing film-forming agents containing siloxane groups 6 Oleic acid imidazoline 3 Diene-succinimide T154 (number average molecular weight 1300) 12 Polyisobutylene Mannich base (number average molecular weight 1000) 8 High-boiling-point aromatic solvent oil SA-1500 (boiling range 200~280℃) 43

[0044] The preparation method of the above-mentioned composite anti-scorching and scale inhibitor is as follows:

[0045] 1. Preparation of temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor

[0046] (1) Antioxidant loading: The mass ratio of the carrier (MCM-41 type mesoporous silica, pore size 8nm, specific surface area 1050m² / g, particle size 80nm) to the composite antioxidant is 1:1; the mass ratio of 2,6-di-tert-butyl-4-methylphenol (BHT) to N-phenyl-α-naphthylamine (antioxidant A) in the composite antioxidant is 1:1. BHT and antioxidant A were dissolved in anhydrous ethanol to prepare a mixed solution with a mass concentration of 25%. The carrier, which was vacuum dried at 120℃ for 4h, was immersed in the mixed solution, stirred and immersed at room temperature for 12h, and vacuum dried at 80℃ for 6h to obtain mesoporous silica loaded with composite antioxidant.

[0047] (2) Deposition and coating of basic magnesium carbonate: Basic magnesium carbonate (4MgCO3·Mg(OH)2·5H2O) was dispersed in deionized water, and Span-80 (2% of the mass of basic magnesium carbonate) was added to prepare an 8% suspension; mesoporous silica loaded with composite antioxidant was dispersed in the basic magnesium carbonate suspension, and the amount of basic magnesium carbonate coating was 15% of the mass of mesoporous silica. The mixture was stirred at 70℃ for 2.5h to uniformly deposit and coat the surface of the mesoporous silica particles with basic magnesium carbonate, filtered, and vacuum dried at 80℃ for 4h to obtain a temperature-responsive nano-mesoporous silica loaded with composite antioxidant polymerization inhibitor.

[0048] (3) Preparation of self-healing film-forming agent containing siloxane group: aminopropyltriethoxysilane and 4-boronicobenzoic acid were mixed in a molar ratio of 1:1.1 and reacted at 150°C for 5 h under nitrogen protection. Water and low-boiling substances were removed by vacuum distillation to obtain a silane coupling agent self-healing film-forming agent containing borate ester dynamic covalent bond.

[0049] (4) Compounding: Add high-boiling-point aromatic solvent oil to the reactor, heat to 55°C, and add T551, free antioxidant polymerization inhibitor (BHT to antioxidant A mass ratio of 1:1), temperature-responsive nano-mesoporous silica supported composite antioxidant polymerization inhibitor, T154 dispersant, self-healing film-forming agent, polyisobutylene Mannich base detergent and oleic acid imidazoline in sequence under stirring. Continue stirring for 1.5h until all components are uniformly dispersed to obtain the final product.

[0050] Example 2

[0051] A composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units, comprising the following components by weight:

[0052] Temperature-responsive nanoporous silica (SBA-15) supported composite antioxidant polymerization inhibitor 15 Free antioxidant polymerization inhibitor (1076 to 4,4'-bis(α,α-dimethylbenzyl)diphenylamine mass ratio 1:1.5) 4 N-Di(2-ethylhexyl)aminomethyl-methylbenzotriazole (T551) 4 Self-healing film-forming agents containing siloxane groups 4 Cycloalkyl imidazoline 2 Diene-succinimide T154 (number average molecular weight 2400) 10 Polyisobutylene Mannich base (number average molecular weight 1000) 6 High-boiling-point aromatic solvent oil SA-1800 (boiling range 180~260℃) 55

[0053] The preparation method of the above-mentioned composite anti-scorching and scale inhibitor is as follows:

[0054] 1. Preparation of temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor

[0055] (1) Antioxidant loading: The mass ratio of the carrier (SBA-15 type mesoporous silica, pore size 10nm, specific surface area 880m² / g, particle size 100nm) to the composite antioxidant was 1:0.8; the mass ratio of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester (1076) to 4,4'-bis(α,α-dimethylbenzyl)diphenylamine in the composite antioxidant was 1:1.5. 1076 and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine were dissolved in anhydrous ethanol to prepare a 20% mass concentration mixed solution. The carrier, which had been vacuum dried at 120℃ for 4h, was immersed in the mixed solution, stirred and immersed at room temperature for 12h, and then vacuum dried at 80℃ for 6h to obtain mesoporous silica loaded with composite antioxidant.

[0056] (2) Deposition and coating of basic magnesium carbonate: Basic magnesium carbonate (4MgCO3·Mg(OH)2·5H2O) was dispersed in deionized water, and Span-80 (1.5% of the mass of basic magnesium carbonate) was added to prepare a 6% suspension; mesoporous silica loaded with composite antioxidant was dispersed in the basic magnesium carbonate suspension, and the amount of basic magnesium carbonate coating was 12% of the mass of mesoporous silica. The mixture was stirred at 65°C for 2 hours to uniformly deposit and coat the surface of the mesoporous silica particles. After filtration and vacuum drying at 80°C for 4 hours, a temperature-responsive nano-mesoporous silica loaded with composite antioxidant polymerization inhibitor was obtained.

[0057] (3) Preparation of self-healing film-forming agent containing siloxane group: aminopropyltriethoxysilane and 4-boronicobenzoic acid were mixed in a molar ratio of 1:1.0 and reacted at 140°C for 6 h under nitrogen protection. Water and low-boiling substances were removed by vacuum distillation to obtain the self-healing film-forming agent.

[0058] (4) Compounding: The compounding method described in Example 1 shall be followed.

[0059] Example 3

[0060] A composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units, comprising the following components by weight:

[0061] Temperature-responsive nanoporous silica (MCM-41) supported composite antioxidant polymerization inhibitor 22 Free antioxidant polymerization inhibitor (BHT to antioxidant A mass ratio of 1:1.8) 5 N-Di(2-ethylhexyl)aminomethyl-methylbenzotriazole (T551) 5 Self-healing film-forming agents containing siloxane groups 8 Oleic acid imidazoline 4 Monoalkenyl succinimide T151 (number average molecular weight 1000) 15 Polyisobutylene Mannich base (number average molecular weight 1000) 10 High-boiling-point aromatic solvent oil SA-1800 (boiling range 220~300℃) 31

[0062] The preparation method of the above-mentioned composite anti-scorching and scale inhibitor is as follows:

[0063] 1. Preparation of temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor

[0064] (1) Antioxidant loading: The mass ratio of the carrier (MCM-41 type mesoporous silica, pore size 6nm, specific surface area 1180m² / g, particle size 60nm) to the composite antioxidant is 1:1.3; the mass ratio of BHT to antioxidant A in the composite antioxidant is 1:1.8. BHT and antioxidant A were dissolved in anhydrous ethanol to prepare a 30% mass concentration mixed solution. The carrier, which was vacuum dried at 120℃ for 4h, was immersed in the mixed solution, stirred and immersed at room temperature for 12h, and vacuum dried at 80℃ for 6h to obtain mesoporous silica loaded with composite antioxidant.

[0065] (2) Deposition and coating of basic magnesium carbonate: Basic magnesium carbonate (4MgCO3·Mg(OH)2·5H2O) was dispersed in deionized water, and Span-80 (3% of the mass of basic magnesium carbonate) was added to prepare a 10% suspension; mesoporous silica loaded with composite antioxidant was dispersed in the basic magnesium carbonate suspension, and the amount of basic magnesium carbonate coating was 18% of the mass of mesoporous silica. The mixture was stirred at 75°C for 3 hours to uniformly deposit and coat the surface of the mesoporous silica particles. After filtration and vacuum drying at 80°C for 4 hours, a temperature-responsive nano-mesoporous silica loaded with composite antioxidant polymerization inhibitor was obtained.

[0066] (3) Preparation of self-healing film-forming agent containing siloxane group: aminopropyltriethoxysilane and 4-boronicobenzoic acid were mixed in a molar ratio of 1:1.2 and reacted at 160°C for 4 h under nitrogen protection. Water and low-boiling substances were removed by vacuum distillation to obtain the self-healing film-forming agent.

[0067] (4) Compounding: The compounding method described in Example 1 shall be followed.

[0068] Example 4

[0069] A composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units, comprising the following components by weight:

[0070] Temperature-responsive nanoporous silica (SBA-15) supported composite antioxidant polymerization inhibitor 25 Free antioxidant polymerization inhibitor (BHT to 4,4'-bis(α,α-dimethylbenzyl)diphenylamine mass ratio 1:2) 2 N-Di(2-ethylhexyl)aminomethyl-methylbenzotriazole (T551) 2 Self-healing film-forming agents containing siloxane groups 4 Cycloalkyl imidazoline 2 Diene-succinimide T154 (number average molecular weight 2400) 10 Polyisobutylene Mannich base (number average molecular weight 1000) 6 High-boiling-point aromatic solvent oil SA-1500 (boiling range 190~290℃) 49

[0071] The preparation method of the above-mentioned composite anti-scorching and scale inhibitor is as follows:

[0072] 1. Preparation of temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor

[0073] (1) Antioxidant loading: The mass ratio of the carrier (SBA-15 type mesoporous silica, pore size 9nm, specific surface area 950m² / g, particle size 90nm) to the composite antioxidant is 1:1.5; the mass ratio of BHT to 4,4'-bis(α,α-dimethylbenzyl)diphenylamine in the composite antioxidant is 1:2. BHT and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine were dissolved in anhydrous ethanol to prepare a mixed solution with a mass concentration of 28%. The carrier, which was vacuum dried at 120℃ for 4h, was immersed in the mixed solution, stirred and immersed at room temperature for 12h, and vacuum dried at 80℃ for 6h to obtain mesoporous silica loaded with composite antioxidant.

[0074] (2) Deposition and coating of basic magnesium carbonate: Basic magnesium carbonate (4MgCO3·Mg(OH)2·5H2O) was dispersed in deionized water, and Span-80 (2.5% of the mass of basic magnesium carbonate) was added to prepare an 8% suspension; mesoporous silica loaded with composite antioxidant was dispersed in the above basic magnesium carbonate suspension, and the amount of basic magnesium carbonate coating was 20% of the mass of mesoporous silica. The mixture was stirred at 80°C for 2 hours to uniformly deposit and coat the surface of the mesoporous silica particles. After filtration and vacuum drying at 80°C for 4 hours, a temperature-responsive nano-mesoporous silica loaded with composite antioxidant polymerization inhibitor was obtained.

[0075] (3) Preparation of self-healing film-forming agent containing siloxane group: aminopropyltriethoxysilane and 4-boronicobenzoic acid were mixed in a molar ratio of 1:1.15 and reacted at 155°C for 5 h under nitrogen protection. Water and low-boiling substances were removed by vacuum distillation to obtain the self-healing film-forming agent.

[0076] (4) Compounding: The compounding method described in Example 1 shall be followed.

[0077] Example 5

[0078] A composite anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units, comprising the following components by weight:

[0079] Temperature-responsive nanoporous silica (SBA-15) supported composite antioxidant polymerization inhibitor 15 Free antioxidant polymerization inhibitor (BHT to 4,4'-bis(α,α-dimethylbenzyl)diphenylamine mass ratio 1:2) 2 N-Di(2-ethylhexyl)aminomethyl-methylbenzotriazole (T551) 2 Self-healing film-forming agents containing siloxane groups 4 Cycloalkyl imidazoline 2 Diene-succinimide T154 (number average molecular weight 2400) 10 Polyisobutylene Mannich base (number average molecular weight 1000) 6 High-boiling-point aromatic solvent oil SA-2000 (boiling range 190~290℃) 59

[0080] The preparation method of the above-mentioned composite anti-scorching and scale inhibitor is described in Example 4.

[0081] Comparative Example 1

[0082] An anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units is prepared by compounding the following components in parts by weight:

[0083] 2,6-Di-tert-butyl-p-cresol (free radical scavenger) 5 Polyisobutylene Mannich base (detergent dispersant) 25 β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester (antioxidant) 6 SA-2000 Solvent Oil 64

[0084] Comparative Example 2

[0085] An anti-coking and scale inhibitor for S-Zorb adsorption desulfurization units is prepared by compounding the following components in parts by weight:

[0086] 2-Octanol (Antioxidant and Polymerization Inhibitor) 25 Aminotriazole (metal passivating agent) 5 Polyisobutylene diimide (detergent dispersant) 18 Oil-soluble imidazoline (film-forming agent) 6 SA-2000 Solvent Oil 46

[0087] Performance evaluation tests of the anti-scorching and scale inhibitors prepared in the embodiments and comparative examples of this invention

[0088] (I) Evaluation Test of Anti-coking and Anti-scaling Performance

[0089] To verify the performance of the anti-scaling and scale inhibitor of the present invention, dynamic simulation scale inhibition tests using an S-Zorb device were conducted on the samples of Examples 1-5 and Comparative Examples 1-2.

[0090] Experimental setup: A self-built S-Zorb device dynamic simulation and evaluation system, including a feeding system, three simulated tubes (material 316L stainless steel, inner diameter 6mm, length 300mm), a temperature control system, and a pressure control system.

[0091] Experimental conditions: The test oil was a feedstock from a petrochemical company's S-Zorb unit (sulfur content 580 μg / g, olefin content 24.5 wt%, diene value 1.8 gI2 / 100g, unwashed gum 5 wt%), with a loading rate of 60 μg / g (based on the feedstock oil). A three-stage heat exchanger was used as a simulation tube, with temperatures of 150℃, 250℃, and 350℃ sequentially. The system pressure was 0.8 MPa, and the oil flow rate was 0.2 m / s. The system operated continuously for 10 days. After the experiment, the pressure drop in the reaction tube was measured, and the results are shown in Table 1.

[0092] Table 1 Evaluation Table of Anti-scorching and Anti-scaling Performance

[0093] Example 1 0.6 3.9 8.1 12.6 Example 2 0.5 4.1 9.5 14.1 Example 3 0.6 3.7 7.5 11.8 Example 4 0.5 4.4 6.3 11.2 Example 5 0.7 5.0 9.6 15.3 Comparative Example 1 0.7 8.4 19.5 28.6 Comparative Example 2 0.5 9.8 15.1 25.4 blank 4.4 10.4 37.5 52.3

[0094] As can be seen from the results in Table 1, the low, medium and high temperature ranges of Examples 1 to 5 of the present invention all have good anti-coking and scale inhibition effects, especially in the high temperature range, their anti-coking and scale inhibition performance is far superior to that of the comparative examples.

[0095] (II) Temperature Response Intelligent Release Performance Evaluation Experiment

[0096] Test setup: Same as the anti-coking and scale inhibition performance evaluation test.

[0097] Test conditions: Samples from Examples 1-5 and Comparative Examples 1-2 were added to the test oil (addition amount 200 μg / g), and samples were taken after each section of the simulated heat exchanger to analyze the content of antioxidant polymerization inhibitor. The test results are shown in Table 2.

[0098] Table 2 Evaluation Table of Temperature Response Intelligent Release Performance

[0099] Example 1 5.7 10.8 17.2 Example 2 4.5 9.4 16.7 Example 3 6.2 13.7 22.3 Example 4 1.1 11.8 24.9 Example 5 1.4 6.3 14.2 Comparative Example 1 5.6 0.8 0.4 Comparative Example 2 41.2 15.6 7.9

[0100] As can be seen from the results in Table 2, under the premise of a high injection amount of 200 μg / g, in Examples 1 to 5 of the present invention, the antioxidant in the system also showed a significant increasing trend with increasing temperature, while in Comparative Examples 1 to 2, the antioxidant showed a decreasing trend with increasing temperature.

[0101] This fully demonstrates the two-stage temperature response characteristics of temperature-responsive nanoporous silica (SBA-15) supported by a composite antioxidant polymerization inhibitor. The comparative example, which directly adds an antioxidant polymerization inhibitor, does not exhibit temperature-responsive functionality.

[0102] (iii) Metal surface film-forming property test

[0103] Test setup: Same as the anti-coking and scale inhibition performance evaluation test.

[0104] Test conditions: 316L stainless steel test pieces were immersed in oil containing various anti-coking and scale inhibitor samples (addition amount 200 μg / g), kept at 350℃ for 24 h, and then removed. The film resistance was measured by electrochemical impedance spectroscopy (EIS) to evaluate the film quality and scouring resistance. Then, the film resistance was measured again after running under oil scouring conditions at a flow rate of 2.0 m / s for 24 h, and the film resistance retention rate was calculated (film resistance retention rate = film resistance after scouring / film resistance before scouring × 100%). The test results are shown in Table 3.

[0105] Table 3 Evaluation Table of Film-Forming Properties of Metal Surfaces

[0106] Example 1 155.2 129.8 83.6 Example 2 140.6 116.3 82.7 Example 3 169.8 146.1 86.0 Example 4 182.5 161.0 88.2 Example 5 167.6 143.5 85.6 Comparative Example 1 42.5 18.6 43.8 Comparative Example 2 68.3 32.5 47.6

[0107] As can be seen from the results in Table 3, the film-forming resistance of the protective films formed in Examples 1 to 5 of the present invention reached 140.6 to 182.5 kΩ·cm², which is much higher than that of Comparative Example 1 (42.5 kΩ·cm²) and Comparative Example 2 (68.3 kΩ·cm²). After 72 hours of rinsing, the film-forming resistance retention rate was still 82.7% to 88.2%, which is significantly higher than that of Comparative Example 1 (43.8%) and Comparative Example 2 (47.6%). This indicates that the BO-Fe / Si-O-Fe dual-anchored chemical bonded protective film formed by the siloxane-containing self-healing film-forming agent of the present invention has excellent compactness and rinsing resistance, and the self-healing function effectively maintains the integrity of the film.

[0108] The above test results fully demonstrate that the "antioxidant-passivation-film formation-dispersion-cleaning-corrosion inhibition" complete protective chain system constructed by the present invention through the synergistic effect of eight components, including temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor, siloxane-containing self-healing film-forming agent, and benzotriazole-type metal passivator, has excellent anti-scorching and scale inhibition effects in low, medium and high temperature ranges, and its comprehensive performance is significantly better than that of the prior art.

[0109] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as...

[0110] This is intended to limit the scope of the invention. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A composite antifouling and scale inhibitor for use in a S-Zorb adsorptive desulfurization unit, characterized in that, Based on parts by weight, it comprises the following components: 15-25 parts of temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor; 2-5 parts of free antioxidant polymerization inhibitor; 2-5 parts of benzotriazole-type metal passivating agent; 4-8 parts of a self-healing film-forming agent containing siloxane groups; 2-4 parts of oil-soluble imidazoline corrosion inhibitor; 10-15 parts of polyisobutylene succinimide dispersant; 6-10 parts of Mannich base-type detergent; 28-59 parts of high-boiling-point aromatic solvent oil.

2. The composite anti-scorching and scale inhibitor according to claim 1, characterized in that, The preparation method of the temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor includes the following steps: (1) First, the carrier is vacuum dried at 120℃ for 4h, cooled to room temperature, and then the free antioxidant polymerization inhibitor is dissolved in anhydrous ethanol to obtain a mixed solution with a mass concentration of 20-30%; then the dried carrier is immersed in the above mixed solution, stirred and immersed at room temperature for 12h, and finally vacuum dried at 80℃ for 6h to obtain mesoporous silica loaded with composite antioxidant; wherein, the carrier is MCM-41 type or SBA-15 type mesoporous silica, the pore size of the carrier is 6-10nm, the specific surface area is 800-1200m² / g, and the particle size is 50-100nm; (2) First, basic magnesium carbonate is dispersed in deionized water, and an oil-soluble surfactant is added to obtain a 5-10% basic magnesium carbonate suspension. Then, the mesoporous silica loaded with composite antioxidant obtained in step (1) is dispersed in the above basic magnesium carbonate suspension and stirred at 60-80°C for 2-3 hours. Finally, it is filtered and vacuum dried at 80°C for 4 hours to obtain a temperature-responsive nano-mesoporous silica loaded with composite antioxidant polymerization inhibitor. The mass of the oil-soluble surfactant is 1.5-3% of the mass of basic magnesium carbonate.

3. The composite anti-scorching and scale inhibitor according to claim 1 or 2, characterized in that, The free antioxidant polymerization inhibitor is obtained by compounding hindered phenolic antioxidants and aromatic amine antioxidants, with the mass ratio of hindered phenolic antioxidants to aromatic amine antioxidants being 1:0.5 to 1:

2.

4. The composite anti-scorching and scale inhibitor according to claim 3, characterized in that, The hindered phenolic antioxidant is selected from 2,6-di-tert-butyl-4-methylphenol or β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, and the aromatic amine antioxidant is selected from N-phenyl-α-naphthylamine or 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

5. The composite anti-scorching and scale inhibitor according to claim 1, characterized in that, The benzotriazole-type metal passivating agent is N-di(2-ethylhexyl)aminomethyl-methylbenzotriazole.

6. The composite anti-scorching and scale inhibitor according to claim 1, characterized in that, The preparation method of the self-healing film-forming agent containing siloxane groups is as follows: aminopropyltriethoxysilane and 4-boronicobenzoic acid are mixed at a molar ratio of 1:1.0 to 1.2, and reacted at 140 to 160°C for 4 to 6 hours under nitrogen protection. Water and low-boiling substances are removed by vacuum distillation to obtain the self-healing film-forming agent containing siloxane groups.

7. The composite anti-scorching and scale inhibitor according to claim 1, characterized in that, The oil-soluble imidazoline corrosion inhibitor is selected from oleic acid imidazoline and / or cycloalkanoic acid imidazoline.

8. The composite anti-scorching and scale inhibitor according to claim 1, characterized in that, The polyisobutylene succinimide dispersant is selected from monoalkenyl succinimide and / or diene succinimide.

9. The composite anti-scorching and scale inhibitor according to claim 1, characterized in that, The Mannich base type detergent is a polyisobutylene Mannich base prepared by the Mannich reaction of highly active polyisobutylene, polyethylene polyamine and formaldehyde.

10. The preparation method of the composite anti-scorching and scale inhibitor according to claim 1, characterized in that, Includes the following steps: High-boiling-point aromatic solvent oil is added to a reaction vessel and heated to 50-60°C. Under stirring conditions, benzotriazole-type metal passivator, free antioxidant polymerization inhibitor, prepared temperature-responsive nanoporous silica-supported composite antioxidant polymerization inhibitor, polyisobutylene succinimide dispersant, prepared self-healing film-forming agent, Mannich base-type detergent, and oil-soluble imidazoline corrosion inhibitor are added sequentially. Stirring is continued for 1-2 hours until all components are uniformly dispersed to obtain a composite anti-scorching and scale inhibitor.

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