A modified crude oil catalytic cracking enhancement aid and a method of making the same

Abstract

This invention discloses a modified crude oil catalytic cracking enhancement additive, the raw materials of which, by weight, include 80-100 parts of polymethylhydrosiloxane, 150-200 parts of triazine-bis(silane sulfide)-allyl sulfide, 40-50 parts of diethyl vinylphosphonate, 10-20 parts of styrene, and 600-800 parts of kaolin microspheres. This additive uses polymethylhydrosiloxane as the main chain, grafting various functional monomers via hydrosilylation, followed by hydrolysis, loading, and calcination anchoring. This allows the polymer side chains to form silicon-aluminum bonds with kaolin, while the main chain undergoes oxidative condensation to construct a silicon-oxygen-silicon network, covalently integrating and firmly anchoring multiple functional groups to the carrier surface. This invention can improve upon the problems of poor synergistic mixing of existing single-functional additives, insufficient thermal stability of small molecules, low carrier anchoring strength, and dispersed functional sites, resulting in low mass transfer efficiency.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a modified crude oil catalytic cracking enhancement agent and its preparation method. Background Technology

[0002] The trend of crude oil becoming heavier and of lower quality is becoming increasingly significant. Catalytic cracking, as a core process in petroleum refining, faces the challenge of continuously rising levels of heavy metals, macromolecular colloids, and asphaltenes in feedstocks. In existing technologies, catalytic cracking additives are mostly designed around a single function, such as only having metal passivation capabilities, only having the function of increasing octane number, or only having the function of increasing low-carbon olefin production. In industrial applications, multiple single-function additives are usually physically blended with the main catalyst. However, different additives differ in fluidization performance, hydrothermal stability, and adsorption behavior on the catalyst surface, which can easily lead to uneven distribution within the unit, competitive adsorption of functional components, and a decline in synergistic efficiency over operating cycles.

[0003] Furthermore, the active components of existing additives are mostly small organic molecules or simple inorganic salts, which lack thermal stability in the high-temperature, steamy environment of catalytic cracking reactors and regenerators. They are prone to decomposition, volatilization, or migration and loss, resulting in short effective lifespans and frequent replenishment. Although some additives can be loaded onto the carrier surface through impregnation, they mainly rely on physical adsorption or weak interactions for fixation. Under high-speed circulation and scouring in fluidized beds, they are easily detached, and their wear index is difficult to meet the requirements for long-term operation. More importantly, functions such as metal passivation, acid cracking, and diffusion promotion belong to different molecules or different phases. The transfer of reactants between functional sites requires multiple desorption and re-adsorption processes, resulting in high mass transfer resistance and making it difficult to form efficient reaction cascade pathways, thus restricting the overall effectiveness of the additives.

[0004] Therefore, there is an urgent need to develop a novel catalytic cracking additive that covalently integrates multiple functional groups into the same heat-resistant framework and is firmly anchored to the surface of the support through chemical bonding, in order to solve the technical problems of poor physical mixing synergy, insufficient thermal stability of small organic molecules, weak support anchoring strength, and low mass transfer efficiency caused by spatial separation of functional sites in existing single functional additives. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a modified crude oil catalytic cracking enhancement additive and its preparation method. The core design concept of this modified crude oil catalytic cracking enhancement additive is based on a polysiloxane main chain. Through hydrosilylation, metal passivation units, cracking active center precursors, and aromatic pre-adsorption units are covalently grafted onto the same comb-shaped polymer molecule. Furthermore, through controlled hydrolysis and calcination, the side-chain silane groups and residual active sites of the main chain form silicon-aluminum covalent bonds and a silicon-oxygen-silicon crosslinking network with the surface of the kaolinite carrier, constructing a multi-point chemical anchoring.

[0006] The technical solution for achieving the objective of this invention is as follows: A modified crude oil catalytic cracking enhancement additive, by weight, comprises 80-100 parts of polymethylhydrosiloxane, 150-200 parts of triazine-bis(silane sulfide)-allyl sulfide, 40-50 parts of diethyl vinylphosphonate, 10-20 parts of styrene, and 600-800 parts of kaolin microspheres; the additive has polymethylhydrosiloxane as the main chain, and triazine-bis(silane sulfide)-allyl sulfide, diethyl vinylphosphonate, and styrene are covalently grafted onto the same comb-shaped polymer molecule through a hydrosilylation reaction. After hydrolysis of phosphonate, controlled hydrolysis of silane, carrier loading, and calcination anchoring, the silanol groups of the polymer side chain form siloxane-aluminum bonds with the hydroxyl groups on the surface of kaolin, and the residual silane-hydrogen bonds in the main chain undergo oxidative self-condensation to form a siloxane-silicon network.

[0007] The polymethylhydrosiloxane has a molecular weight of 2000~10000 and a hydrogen content of 1.5wt%~1.6wt%.

[0008] The triazine-bis(silane sulfide)-allylic sulfide is prepared in-house, and the preparation method includes the following steps: After the mercaptosilane coupling agent was mixed evenly with potassium carbonate, it was added dropwise to 2,4,6-trichloro-1,3,5-triazine. After the addition was complete, the reaction was carried out, and the triazine intermediate was obtained after purification. The triazine intermediate was then mixed with allyl mercaptan and potassium carbonate and reacted. After the reaction was completed, the triazine-bis(silane sulfide)-allyl sulfide was obtained after purification.

[0009] The molar ratio of the 2,4,6-trichloro-1,3,5-triazine to the mercaptosilane coupling agent is 1:(2.0~2.1); the molar ratio of the triazine intermediate to allyl mercaptan is 1:(1.0~1.2); the mercaptosilane coupling agent is selected from one or two of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; the Karstedt catalyst, based on platinum atoms, has a molar ratio of (50~200)×10⁻⁶ to the silicon-hydrogen bond. -6 That is, 50~200 ppm.

[0010] In the hydrosilylation reaction, the thioether bonds in the triazine-bis(silane thioether)-allylic thioether monomer exert a coordination poisoning effect on the platinum atoms in the Karstedt catalyst, a well-known fact in organosilicon chemistry. To overcome this poisoning effect, this invention increases the amount of Karstedt catalyst from the conventional 10-50 ppm to 50-200 ppm, based on the molar ratio of platinum atoms to hydrogen silane bonds. By increasing the catalyst concentration, the loss of active sites caused by thioether coordination is compensated, allowing the hydrosilylation reaction to proceed smoothly and yielding a comb-shaped polymer with a controllable structure. Simultaneously, the moderate decrease in reaction rate brought about by the sulfur-containing monomer actually helps to avoid excessive crosslinking during the hydrosilylation process, resulting in a more regular and controllable grafted structure.

[0011] In the triazine-bis(silane sulfide)-allylic sulfide monomer, the electron-withdrawing conjugation effect of the triazine ring reduces the electron cloud density of the sulfide bond, weakening its coordination poisoning effect on the platinum catalyst. Samples were taken every 2 hours during the reaction, and the disappearance rate of the allyl characteristic peak was monitored by nuclear magnetic resonance hydrogen spectrum to confirm that the conversion rate was ≥80%.

[0012] The phosphonate hydrolysis and silane controlled hydrolysis are performed using a mixture of hydrochloric acid and ethanol; the diethyl ester group of the vinylphosphonate diethyl ester side chain is hydrolyzed to a dihydroxyphosphonoyl group, and the trimethoxysilyl group of the triazine side chain is partially hydrolyzed to a silanol, with the degree of hydrolysis controlled at 20-40%.

[0013] The kaolin microspheres have a particle size of 50~90 μm and are pre-calcined at 400~450℃ to remove impurities. In the carrier loading step, the hydrolyzed polymer is dispersed in a mixed solvent of ethanol and water, and after adding the kaolin microspheres, it is emulsified and dispersed by high-speed shearing. It is then dried by a spray dryer with an inlet temperature of 220~240℃, an outlet temperature of 100~120℃, and a spray disc rotation speed of 8000~12000 rpm.

[0014] The calcination anchoring process is carried out in an air atmosphere using a programmed temperature increase: first, the temperature is increased to 110-130℃ at a rate of 1-3℃ / min and held for 1-2 hours to remove physically adsorbed water; then, the temperature is increased to 280-320℃ at a rate of 4-6℃ / min and held for 1-3 hours to allow the side-chain silanols to dehydrate and condense with the carrier hydroxyl groups; finally, the temperature is increased to 400-450℃ at a rate of 1-3℃ / min and held for 1-2 hours to allow the residual silane bonds in the main chain to oxidize and self-condense; and then the furnace is cooled and the furnace is removed.

[0015] A method for preparing a modified crude oil catalytic cracking enhancement additive, characterized by comprising the following steps: (1) Hydrosilylation copolymerization: Under nitrogen protection, polymethylhydrosiloxane was dissolved in dry toluene, styrene and diethyl vinylphosphonate were added first, and after stirring evenly, Karstedt catalyst was added and the temperature was raised to 80°C for reaction; then triazine-bis(silane sulfide)-allylic sulfide was added and the reaction continued. The characteristic peak of total olefins was monitored by Fourier transform infrared spectroscopy, and the characteristic peak of allyl was monitored by nuclear magnetic resonance hydrogen spectroscopy. The reaction was stopped when the characteristic peak of total olefins basically disappeared and the allyl conversion rate was ≥80%. (2) Removal of platinum catalyst: Add pre-dried activated carbon to the reaction solution, stir at room temperature for 2 h, filter to remove activated carbon, wash the filtrate with dry solvent, combine the filtrate and washings, remove the solvent under reduced pressure to obtain polymer; (3) Phosphonate hydrolysis and silane controlled hydrolysis: The above polymer was transferred to a three-necked flask, a mixture of hydrochloric acid and ethanol was added, the mixture was heated and stirred, and the solvent was removed by vacuum distillation to obtain a viscous polymer containing phosphonate groups and silanol. (4) Carrier loading: The hydrolyzed polymer was dispersed in a mixed solvent of ethanol and water, stirred at room temperature, and kaolin microspheres that had been pre-calcined and purified were added. The mixture was then emulsified and dispersed under high-speed shearing and dried by a spray dryer to obtain near-spherical microsphere particles. (5) Calcination and anchoring: The spray-dried microspheres are placed in a tube furnace and calcined at a constant temperature in an air atmosphere. After cooling in the furnace, they are taken out to obtain the modified crude oil catalytic cracking enhancement agent.

[0016] A catalytic cracking catalyst mixture comprising the above-mentioned modified crude oil catalytic cracking enhancer and commercially available REY catalyst.

[0017] The mass ratio of the modified crude oil catalytic cracking enhancer to the commercially available REY catalyst is (3~15):(85~97).

[0018] A method for applying a catalytic cracking catalyst mixture includes the following steps: loading the mixed catalyst into a catalytic cracking reactor, and operating at a reaction temperature of 500-540℃, a catalyst-to-oil ratio of 5.0-8.0, and a weight hourly space velocity of 10-20 h⁻¹. -1 Under certain conditions, the catalyst undergoes catalytic cracking reaction in contact with crude oil feedstock. The reaction products are fractionated to obtain dry gas, liquefied petroleum gas, gasoline, diesel, and heavy oil fractions. The catalyst is stripped and then enters the regenerator for coking and regeneration at 680~720℃ in an air atmosphere. After regeneration, the catalyst is returned to the reactor for recycling.

[0019] The mechanism of action of this invention is as follows: At the molecular level, the triazine ring and thioether bond synergistically form a bidentate coordination structure for heavy metal ions such as nickel and vanadium. Through the synergistic chelation of nitrogen and sulfur atoms, the heavy metals are fixed on the catalyst surface in the form of inactive complexes, inhibiting their dehydrogenation activity and reducing the formation of dry gas and coke. The phosphonic acid group, after hydrolysis, provides a moderately strong protic acid center, which can selectively catalyze the secondary cracking reaction of hydrocarbons in gasoline fractions, promoting the formation of low-carbon olefins while avoiding excessive cracking that leads to an increase in dry gas yield. The phenyl side chain pre-adsorbs polycyclic aromatic hydrocarbons in the feedstock through π-π stacking, shortening the diffusion path of heavy macromolecules to the active center and reducing the probability of condensation and coking due to prolonged residence on the catalyst surface.

[0020] The polysiloxane backbone serves as a heat-resistant inorganic framework, maintaining structural integrity in high-temperature hydrothermal environments. It provides physical support and a protective barrier for the side-chain functional groups, reducing direct attack of water vapor on functional sites. The silane groups on the side chains and the silanol groups generated by the oxidation of the backbone dehydrate and condense with the hydroxyl groups on the carrier surface, forming a three-dimensional cross-linked network. This chemically bonds the active components of the additives firmly to the carrier surface, significantly enhancing resistance to fluidized bed wear.

[0021] The aforementioned functional groups are covalently linked to the same molecular framework at the nanoscale. The metal passivation, cracking activity, and diffusion-promoting functions are spatially adjacent, and reactants can be continuously transferred between different functional domains without undergoing repeated desorption and re-adsorption processes, thus forming an efficient intramolecular tandem reaction pathway.

[0022] Beneficial effects

[0023] The present invention has the following beneficial effects: 1. Molecular-level synergy between metal passivation and cracking activity. The triazine ring and thioether bond synergistically form a bidentate coordination structure for heavy metal ions such as nickel and vanadium, fixing the heavy metals to the additive surface in the form of inactive complexes; the phosphonic acid group provides a moderately strong protic acid center, promoting the secondary cracking reaction of hydrocarbons in gasoline fractions. The two functional groups are covalently linked to the same polysiloxane backbone, which is expected to alleviate the problems of competitive adsorption and uneven distribution when single functional additives are physically blended.

[0024] 2. Improved hydrothermal stability and wear resistance. The polysiloxane backbone serves as a heat-resistant inorganic framework, maintaining structural integrity in the high-temperature steam environment of the regenerator. The silanol groups on the side chains and the silanol groups generated by the oxidation of the backbone dehydrate and condense with the hydroxyl groups on the carrier surface, forming a three-dimensional cross-linked network. This allows the active components of the additives to be firmly fixed by chemical bonding, significantly reducing the wear and loss rate during high-speed circulation in the fluidized bed.

[0025] 3. Optimization of diffusion pathways and improvement of product distribution. The phenethyl side chain pre-adsorbs polycyclic aromatic hydrocarbons in the feedstock through π-π stacking, shortening the diffusion path of heavy macromolecules to the active center and reducing the probability of them condensing and forming coke due to prolonged residence on the catalyst surface, thereby improving heavy oil conversion and coke selectivity.

[0026] Furthermore, the additive of this invention has good physical compatibility with existing catalytic cracking main catalysts and conventional combustion improvers and sulfur transfer agents, and can be put into use without structural modifications to existing equipment, demonstrating strong process adaptability. Attached Figure Description

[0027] Figure 1 This is a synthetic circuit diagram of triazine-bis(silane sulfide)-allylic sulfide.

[0028] Figure 2The NMR spectrum of triazine-bis(silane sulfide)-allylic sulfide is shown in the 1H NMR spectrum. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0031] The raw materials and equipment used in the examples and comparative examples are described below, where eq represents molar equivalent: Polymethylhydrosiloxane: Trimethylsilyl-terminated polymethylhydrosiloxane, with a hydrogen content of 1.5wt%~1.6wt% based on silane-hydrogen bonds and a molecular weight of 2100~2400, commercially available.

[0032] Activated carbon: 200~300 mesh, commercially available.

[0033] Kaolin microspheres: particle size 50~90 μm, commercially available.

[0034] Commercially available REY catalyst: REY-15 molecular sieve, containing 13.5~16.5% RE2O3 mixed rare earth oxides, commercially available, aged at 800℃ and 100% steam for 17 hours.

[0035] Triazine-bis(silane sulfide)-allylic sulfide: prepared in-house, the preparation method is as follows: Under nitrogen protection, 1.0 eq of 2,4,6-trichloro-1,3,5-triazine was dissolved in dry tetrahydrofuran and cooled to 0°C. 2.0 eq of mercaptopropyltrimethoxysilane was dissolved in a small amount of dry tetrahydrofuran, and 2.2 eq of anhydrous potassium carbonate was added to form a suspension. This suspension was slowly added dropwise to the solution, with the addition time controlled at 1 h. After the addition was complete, the mixture was heated to room temperature and stirred for 4 h, then heated to 35°C and reacted for another 3 h. Heating was stopped after the starting material spot disappeared as monitored by thin-layer chromatography. The mixture was cooled to room temperature, filtered, and the filtrate was washed with saturated sodium chloride solution. The organic phase was dried over anhydrous sodium sulfate, and the filtrate was purified at 40°C under reduced pressure to remove tetrahydrofuran. The filtrate was then purified by silica gel column chromatography treated with triethylamine to obtain 1,3,5-triazine with a 2,4-position 3-trimethoxysilylpropylthio group and a 6-position chlorine group. Under nitrogen protection, 1.0 eq of 2,4,6-trichloro-1,3,5-triazine was dissolved in dry tetrahydrofuran and cooled to 0°C. The product obtained above was dissolved in dry tetrahydrofuran, and 1.2 eq of allyl mercaptan and 1.5 eq of anhydrous potassium carbonate were added. After stirring at room temperature for 2 h, the temperature was raised to 55 °C and reacted for 5 h. The disappearance of the starting material spot was monitored by thin-layer chromatography. After the reaction was completed, the mixture was filtered, and the filtrate was washed with saturated sodium chloride solution. The organic phase was dried over anhydrous sodium sulfate, and the tetrahydrofuran was removed from the filtrate at 40 °C under reduced pressure. The product was purified by silica gel column chromatography after treatment with triethylamine to obtain triazine-bis(silane sulfide)-allyl sulfide, with the structure shown below: .

[0036] Triazine-bis(allyl sulfide)-silane sulfide: prepared in-house, the preparation method is the same as that of triazine-bis(allyl sulfide)-allyl sulfide, except that 2.0 eq mercaptopropyltrimethoxysilane is replaced with 1.0 eq and 1.2 eq allyl mercaptan is replaced with 2.2 eq, while other conditions remain unchanged, to obtain triazine-bis(allyl sulfide)-silane sulfide.

[0037] Vinyltrimethoxysilane: Commercially available.

[0038] Triazine-allyl sulfide: Prepared in-house. The preparation method differs from that of triazine-bis(silane sulfide)-allyl sulfide in that mercaptopropyltrimethoxysilane is not added. Instead, 1.0 eq of allyl mercaptan and 1.0 eq of 2,4,6-trichloro-1,3,5-triazine are reacted in dry tetrahydrofuran at 0°C. The reaction is monitored by thin-layer chromatography until the starting material spot disappears. All other post-treatment conditions remain unchanged to obtain 2-allylthio-4,6-dichloro-1,3,5-triazine, i.e., triazine-allyl sulfide.

[0039] Example 1

[0040] Modified crude oil catalytic cracking enhancement additive 1: self-made, preparation method as follows: S1. Hydrosilylation copolymerization: Under nitrogen protection, 90 parts by weight of polymethylhydrosiloxane and dry toluene were added to a three-necked flask that had been dried at 120°C for 12 h and assembled while still hot. The mixture was stirred to dissolve the siloxane. Then, 15 parts by weight of styrene and 45 parts by weight of diethyl vinylphosphonate were added and stirred until homogeneous. Finally, Karstedt catalyst (toluene solution with a platinum concentration of 2% based on platinum atoms) was added at a molar amount of 125 ppm of siloxane-hydrogen bond based on platinum atoms. The mixture was heated to 80°C and stirred for 3 h. Subsequently, 175 parts by weight of triazine-bis(silane sulfide)-allylic sulfide was dissolved in dry toluene and slowly added dropwise to the above reaction solution. After the addition was complete, the reaction was continued at 80°C for 4-6 h. Samples were taken every 2 h during the reaction. The stretching vibration peak of the siloxane-hydrogen bond was detected by Fourier transform infrared spectroscopy, and the disappearance rate of the allyl characteristic peak was monitored by nuclear magnetic resonance hydrogen spectroscopy. When the allyl conversion rate was ≥80%, the reaction was stopped and cooled to room temperature. S2. Removal of platinum catalyst: 15 parts by weight of pre-dried activated carbon were added to the reaction solution and stirred at room temperature for 2 h to adsorb platinum complex. The activated carbon was removed by filtration. The activated carbon filter cake was washed twice with dry toluene. The filtrate and washing liquid were combined and the toluene was removed under reduced pressure at 40 °C to obtain the polymer. S3. Phosphonate hydrolysis and controlled silane hydrolysis: The above polymer was transferred to a three-necked flask, and a mixture of 0.5 M hydrochloric acid and ethanol (volume ratio 1:6), with a total mass three times the polymer mass, was added. The mixture was heated to 55°C and stirred for 6 h. Under these conditions, the diethyl ester group of the vinylphosphonate side chain preferentially hydrolyzed to a dihydroxyphosphonoyl group; the trimethoxysilyl group of the triazine side chain partially hydrolyzed to a silanol. The degree of hydrolysis was controlled at 20-40%. 29 Si-NMR characteristic peak monitoring showed that the residual methoxysilane was further hydrolyzed and condensed in the subsequent support loading step. After the reaction was completed, the solvent was removed by vacuum evaporation to obtain a viscous polymer containing phosphonic acid groups and silanols. S4. Carrier loading: The above-mentioned hydrolyzed polymer was dispersed in a mixed solvent of ethanol and water with a volume ratio of 3:1 and a total mass of 1.5 times the polymer mass. The mixture was stirred at room temperature for 2 h to ensure full dispersion. 700 parts by weight of kaolin microspheres that had been calcined at 420℃ to remove impurities were added. The mixture was then emulsified and dispersed at high speed for 35 min to achieve uniform dispersion of the polymer containing phosphonic acid groups and silanols on the surface of the kaolin microspheres. The slurry was dried by spray drying, with an inlet temperature of 230℃, an outlet temperature of 110℃, and a spray disk rotation speed of 10000 rpm, to obtain near-spherical microspheres with a particle size concentration of 50~90 μm. S5. Calcination and Anchoring: The spray-dried microspheres are placed in a tube furnace and heated to 120°C at a rate of 2°C / min and held for 1 h in an air atmosphere to remove physically adsorbed water. Then, the temperature is increased to 300°C at a rate of 5°C / min and held for 2 h to allow the side chain silanol groups to fully dehydrate and condense with the hydroxyl groups on the surface of kaolin to form silicon-aluminum bonds. Finally, the temperature is increased to 450°C at a rate of 2°C / min and held for 1 h to oxidize the residual silicon-hydrogen bonds in the main chain to silanols and self-condense to form a silicon-oxygen-silicon network. The entire calcination process is carried out in an air atmosphere. During this process, the silanol groups on the polymer side chain undergo dehydration condensation with the hydroxyl groups on the kaolin surface to form covalent silicon-aluminum bonds; the residual silicon-hydrogen bonds in the main chain are oxidized to silanols and further self-condense to form a silicon-oxygen-silicon network; the phosphonic acid groups undergo partial dehydration condensation at 450°C to form a polyphosphonic acid network, which interacts with the support surface and the polymer backbone, thus improving the dispersion stability of the phosphonic acid groups on the support surface; after being cooled to below 100°C in the furnace, the modified crude oil catalytic cracking enhancement additive 1 is obtained.

[0041] Example 2

[0042] Modified crude oil catalytic cracking enhancement additive 2: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that polymethylhydrosiloxane is replaced with 80 parts, triazine-bis(silane sulfide)-allylic sulfide is replaced with 150 parts, diethyl vinylphosphonate is replaced with 40 parts, styrene is replaced with 10 parts, kaolin microspheres are replaced with 600 parts, and Karstedt catalyst is replaced with 50 ppm. All other conditions remain unchanged to obtain modified crude oil catalytic cracking enhancement additive 2.

[0043] Example 3

[0044] Modified crude oil catalytic cracking enhancement additive 3: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that polymethylhydrosiloxane is replaced with 100 parts, triazine-bis(silane sulfide)-allylic sulfide is replaced with 200 parts, diethyl vinylphosphonate is replaced with 50 parts, styrene is replaced with 20 parts, kaolin microspheres are replaced with 800 parts, and Karstedt catalyst is replaced with 200 ppm. All other conditions remain unchanged to obtain modified crude oil catalytic cracking enhancement additive 3.

[0045] Example 4

[0046] Modified crude oil catalytic cracking enhancement additive 4: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that triazine-bis(silane sulfide)-allyl sulfide is replaced with triazine-bis(allyl sulfide)-silane sulfide, while other conditions remain unchanged, thus obtaining modified crude oil catalytic cracking enhancement additive 4.

[0047] Comparative Example 1 Modified crude oil catalytic cracking enhancement additive 5: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that triazine-bis(silane sulfide)-allylic sulfide is replaced with an equimolar amount of vinyltrimethoxysilane, while other conditions remain unchanged, thus obtaining modified crude oil catalytic cracking enhancement additive 5.

[0048] Comparative Example 2 Modified crude oil catalytic cracking enhancement additive 6: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that triazine-bis(silane sulfide)-allylic sulfide is replaced with an equimolar amount of triazine-allylic sulfide, while other conditions remain unchanged, thus obtaining modified crude oil catalytic cracking enhancement additive 6.

[0049] Comparative Example 3 Modified crude oil catalytic cracking enhancement additive 7: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that the amount of Karstedt catalyst is replaced with 20 ppm, while other conditions remain unchanged. After 6 h of reaction, the stretching vibration peak of silicon-hydrogen bonds was detected by Fourier transform infrared spectroscopy. Its intensity decreased by only 12% compared with the initial value, proving that in the presence of sulfur-containing monomers, conventional low-dosage catalysts have low catalytic efficiency due to sulfide coordination poisoning, and cannot obtain grafted polymers with controllable structure.

[0050] Comparative Example 4 Modified crude oil catalytic cracking enhancement additive 8: self-made. The preparation method is the same as that of modified crude oil catalytic cracking enhancement additive 1, except that 175 parts by weight of triazine-bis(silane sulfide)-allylic sulfide is replaced with an equimolar amount of vinyltrimethoxysilane, the Karstedt catalyst dosage is maintained at 125 ppm, and other conditions remain unchanged. After 1.5 h of reaction, the system showed obvious gelation, the viscosity increased, and effective stirring could not continue. This proves that the sulfur-free system reacts too quickly under the same high catalyst dosage, making it difficult to obtain a grafted polymer with controllable structure. In contrast, Example 1 of this application can react stably for more than 6 h under the same conditions without gel formation.

[0051] Application examples Application Example 1 Mixed catalyst 1: Self-made, preparation method as follows: Modified crude oil catalytic cracking enhancement additive 1 and commercially available REY catalyst were mechanically mixed in a high-speed mixer at a mass ratio of 10:90 for 10 min to obtain mixed catalyst 1.

[0052] Application Example 2 Mixed catalyst 2: self-made. The preparation method is the same as that of mixed catalyst 1, except that the mass ratio of modified crude oil catalytic cracking enhancer 1 to commercially available REY catalyst is replaced with 5:95, while other conditions remain unchanged, thus obtaining mixed catalyst 2.

[0053] Application Example 3 Mixed catalyst 3: self-made. The preparation method is the same as that of mixed catalyst 1, except that the mass ratio of modified crude oil catalytic cracking enhancer 1 to commercially available REY catalyst is replaced with 15:85, while other conditions remain unchanged, thus obtaining mixed catalyst 3.

[0054] Application Example 4 Mixed catalyst 4: self-made. The preparation method is the same as that of mixed catalyst 1, except that modified crude oil catalytic cracking enhancement agent 1 is replaced with modified crude oil catalytic cracking enhancement agent 2, while other conditions remain unchanged, thus obtaining mixed catalyst 4.

[0055] Application Example 5 Mixed catalyst 5: self-made. The preparation method is the same as that of mixed catalyst 1, except that modified crude oil catalytic cracking enhancement agent 1 is replaced with modified crude oil catalytic cracking enhancement agent 3, while other conditions remain unchanged, thus obtaining mixed catalyst 5.

[0056] Application Example 6 Mixed catalyst 6: self-made. The preparation method is the same as that of mixed catalyst 1, except that modified crude oil catalytic cracking enhancement agent 1 is replaced with modified crude oil catalytic cracking enhancement agent 4, while other conditions remain unchanged, thus obtaining mixed catalyst 6.

[0057] Comparative Application Example 1 Mixed catalyst 7: self-made. The preparation method is the same as that of mixed catalyst 1, except that modified crude oil catalytic cracking enhancement agent 1 is replaced with modified crude oil catalytic cracking enhancement agent 5, while other conditions remain unchanged, thus obtaining mixed catalyst 7.

[0058] Comparative Application Example 2 Mixed catalyst 8: self-made. The preparation method is the same as that of mixed catalyst 1, except that modified crude oil catalytic cracking enhancement agent 1 is replaced with modified crude oil catalytic cracking enhancement agent 6, while other conditions remain unchanged, thus obtaining mixed catalyst 8.

[0059] The following are the test methods for performance parameters involved in this invention: 1. Nuclear magnetic resonance hydrogen spectrum test: Characterization was performed using a nuclear magnetic resonance spectrometer (Bruker AM-600, Avance 600).

[0060] 2. Microreactor activity index: determined according to NB / SH / T 0952-2017 "Determination of Microreactor Activity Index of Catalytic Cracking Catalysts".

[0061] 3. Apparent loose density: determined according to NB / SH / T 0954-2017 "Determination of Apparent Loose Density of Catalytic Cracking Catalysts".

[0062] 4. Pore volume: determined according to NB / SH / T 0955-2017 "Determination of pore volume of catalytic cracking catalyst by water drop method".

[0063] 5. Wear index: Determined according to NB / SH / T 0964-2017 "Determination of wear index of catalytic cracking catalyst - straight tube method".

[0064] The catalytic cracking additive of this invention and a commercially available catalyst were mixed in a specific ratio to form a catalyst mixture. The catalyst mixture was then aged at 800°C with 100% water vapor for 17 hours in a fixed-bed aging unit. Evaluation was then conducted on an ACE unit. The properties of the feedstock used for evaluation are shown in Table 1, and the properties of the commercially available REY catalyst are shown in Table 2. The reaction temperature, catalyst-to-oil ratio, weight hourly space velocity, and evaluation results are listed in Table 3. Wherein, conversion rate = gasoline yield + LPG yield + dry gas yield + coke yield; propylene concentration in LPG = propylene yield / LPG yield.

[0065] Table 1 Properties of Crude Oil

[0066] Table 2 Properties of commercially available REY catalysts

[0067] Table 3. Test results of Application Examples 1-6 and Comparative Application Examples 1-2

[0068] Application Example 1 is a reference test group using the optimal formulation and conventional blending ratio. The test results show that the heavy oil conversion reaction is relatively complete, the total yield of light oil products is relatively high, the propylene selectivity and propylene enrichment in liquefied petroleum gas are relatively good, and the generation of by-products such as dry gas and coke is controlled. This demonstrates the passivation effect of the triazine sulfide bidentate chelate structure on heavy metals, the selective cracking activity regulation effect of the phosphonic acid group, and the pre-adsorption and diffusion promotion effect of the phenethyl side chain on aromatic macromolecules. Combined with the heat-resistant anchoring network formed by the polysiloxane backbone, a multi-component functional synergistic effect is achieved. In Application Example 2, after reducing the additive blending ratio, the various performance indicators decreased compared to Application Example 1, but overall, it was still better than the blank control group. This indicates that insufficient additive dosage leads to a decrease in functional site density, weakening the synergistic effect. In Application Example 3, increasing the additive blending ratio resulted in a slight increase or near-perfect improvement in heavy oil conversion depth and propylene enrichment compared to Application Example 1. The total yield of light oil products did not continuously increase with increasing additive dosage, indicating that excessive additive addition can dilute the active centers of the main catalyst, suggesting a reasonable upper limit for the additive blending ratio. In Application Example 4, using a low-loading formulation of the active component, the heavy oil conversion depth and low-carbon olefin yield decreased compared to Application Example 1, indicating insufficient functional density of triazine sulfide and phosphonic acid groups, failing to fully utilize the dual effects of metal passivation and secondary cracking. In Application Example 5, using a high-loading formulation of the active component, the heavy oil conversion depth, propylene yield, and liquefied petroleum gas quality further improved compared to Application Example 1, demonstrating that increasing the density of the functional side chains of the additive itself can optimize the catalytic cracking effect when the additive blending ratio is fixed. Application Example 6 uses a triazine monomer modified with diallyl sulfide and containing only a single silane anchoring arm to prepare an additive. Its heavy oil conversion depth and propylene selectivity are significantly lower than in Application Example 1, while the heavy oil yield is higher. This is because the anchoring point density is insufficient, making the additive prone to loss or uneven dispersion during fluidization. Simultaneously, the diallyl sulfide structure is prone to cross-linking entanglement, reducing the effective utilization rate of functional sites. In contrast, Application Example 1 uses a pure siloxane polymer additive without a triazine ring. Its dry gas yield is higher, but its propylene yield and liquefied petroleum gas quality are lower, and its heavy oil conversion effect is poor. This indicates that without a metal passivation structure, heavy metals such as nickel and vanadium in the feedstock easily promote dehydrogenation reactions, exacerbating the formation of dry gas and coke. In contrast, Application Example 2 uses a triazine derivative additive without a silane anchoring group. Its performance indicators are slightly better than those of Application Example 1, but still lag behind. This indicates that without the chemical bonding anchoring effect of the polysiloxane skeleton, the additive is easily worn away and lost in a hydrothermal fluidization environment, shortening its action cycle and failing to provide long-term stable improvement in catalytic performance. The wear index was significantly negatively correlated with the number of silane anchor arms. In application examples 1-5, the wear index was better than that of single anchor and no anchor system. The micro-reactivity index was better under the dual anchor and triazine ring synergistic passivation structure than that of no triazine ring or no auxiliary anchor, proving that heavy metal passivation and chemical bonding anchor are the dual keys to maintaining cracking activity after hydrothermal aging.Specific surface area and pore volume decrease with increasing additive blending ratio and higher degree of molecular crosslinking. In Application Example 6, the pore volume decreases due to diallyl sulfide crosslinking, becoming the structural root cause of its insufficient cracking activity. In summary, the additive blending ratio in Application Example 1, combined with the bissilane anchoring arm and the triazine-sulfide bidentate coordination structure, achieves the best balance between wear index, microreaction activity, and product distribution. Comparative Example 3 demonstrates that when the Karstedt catalyst dosage is lower than the 50-200 ppm range described in this invention, the coordination poisoning effect of the sulfur-containing monomer on the platinum catalyst makes the hydrosilylation reaction almost impossible, and it is impossible to prepare a structurally controllable graft polymer. Comparative Example 4 demonstrates that even with the high catalyst dosage of 125 ppm described in this invention, if the sulfur-containing monomer is replaced with a conventional sulfur-free vinyl monomer, the system will gel within 1.5 h due to excessively rapid reaction, and it is also impossible to obtain a structurally controllable product. Comparative Examples 3 and 4 together demonstrate the necessity of the technical solution of the present invention: only by simultaneously using sulfur-containing monomers and the high catalyst dosage range of 50~200 ppm described in the present invention can we ensure the smooth progress of the reaction while avoiding excessive cross-linking and obtaining a comb-shaped polymer with a regular structure.

[0069] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A modified crude oil catalytic cracking enhancement additive, characterized in that, The additive is a product obtained by covalently grafting triazine-bis(silane sulfide)-allylic sulfide, diethyl vinyl phosphonate, and styrene onto the side chain of polymethylhydrosiloxane via a hydrosilylation reaction, followed by hydrolysis of the phosphonate ester and controlled hydrolysis of the silane onto the surface of kaolin microspheres, and finally by drying and calcination. The raw materials of the additive, by weight, include 80-100 parts of polymethylhydrosiloxane, 150-200 parts of triazine-bis(silane sulfide)-allylic sulfide, 40-50 parts of diethyl vinyl phosphonate, 10-20 parts of styrene, and 600-800 parts of kaolin microspheres.

2. The modified crude oil catalytic cracking enhancement additive as described in claim 1, characterized in that, The preparation method of the triazine-bis(silane sulfide)-allylic sulfide includes the following steps: After the mercaptosilane coupling agent was mixed evenly with potassium carbonate, it was added dropwise to 2,4,6-trichloro-1,3,5-triazine. After the addition was complete, the reaction was carried out, and the triazine intermediate was obtained after purification. The triazine intermediate was then mixed with allyl mercaptan and potassium carbonate and reacted. After the reaction was completed, the triazine-bis(silane sulfide)-allyl sulfide was obtained after purification.

3. The modified crude oil catalytic cracking enhancement additive as described in claim 1, characterized in that, The molar ratio of 2,4,6-trichloro-1,3,5-triazine to the mercaptosilane coupling agent is 1:(2.0~2.1); the molar ratio of the triazine intermediate to allyl mercaptan is 1:(1.0~1.2); the mercaptosilane coupling agent is selected from one or two of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; the molar ratio of the Karstedt catalyst (based on platinum atoms) to the silicon-hydrogen bond is (50~200)×10⁻⁶. -6 .

4. The modified crude oil catalytic cracking enhancement additive as described in claim 1, characterized in that, The phosphonate hydrolysis and silane controlled hydrolysis are performed using a mixture of hydrochloric acid and ethanol; the diethyl ester group of the vinylphosphonate diethyl ester side chain is hydrolyzed to a dihydroxyphosphonoyl group, and the trimethoxysilyl group of the triazine side chain is partially hydrolyzed to a silanol, with the degree of hydrolysis controlled at 20-40%.

5. The modified crude oil catalytic cracking enhancement additive as described in claim 1, characterized in that, The polymethylhydrosiloxane has a molecular weight of 2000~10000 and a hydrogen content of 1.5wt%~1.6wt%; the kaolin microspheres have a particle size of 50~90 μm and are pre-calcined to remove impurities; in the carrier loading step, the hydrolyzed polymer is dispersed in a mixed solvent of ethanol and water, and after adding the kaolin microspheres, it is emulsified and dispersed by high-speed shearing, and then dried by spray dryer with an inlet temperature of 220~240℃, an outlet temperature of 100~120℃, and an atomizing disc rotation speed of 8000~12000 rpm.

6. The modified crude oil catalytic cracking enhancement additive as described in claim 1, characterized in that, The roasting and anchoring are carried out in an air atmosphere.

7. The method for preparing the modified crude oil catalytic cracking enhancement additive according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Hydrosilylation copolymerization: Under nitrogen protection, polymethylhydrosiloxane was dissolved in dry toluene, styrene and diethyl vinylphosphonate were added first, and after stirring evenly, Karstedt catalyst was added and the temperature was raised to 80°C for reaction; then triazine-bis(silane sulfide)-allylic sulfide was added and the reaction continued. The characteristic peak of total olefins was monitored by Fourier transform infrared spectroscopy, and the characteristic peak of allyl was monitored by nuclear magnetic resonance hydrogen spectroscopy. The reaction was stopped when the characteristic peak of total olefins basically disappeared and the allyl conversion rate was ≥80%. (2) Removal of platinum catalyst: Add pre-dried activated carbon to the reaction solution, stir at room temperature, filter to remove activated carbon, wash the filtrate with dry solvent, combine the filtrate and washings, remove the solvent under reduced pressure to obtain polymer; (3) Phosphonate hydrolysis and silane controlled hydrolysis: The above polymer was transferred to a three-necked flask, a mixture of hydrochloric acid and ethanol was added, the mixture was heated and stirred, and the solvent was removed by vacuum distillation to obtain a viscous polymer containing phosphonate groups and silanol. (4) Carrier loading: The hydrolyzed polymer was dispersed in a mixed solvent of ethanol and water, stirred at room temperature, and kaolin microspheres that had been pre-calcined and purified were added. The mixture was then emulsified and dispersed under high-speed shearing and dried by a spray dryer to obtain near-spherical microsphere particles. (5) Calcination and anchoring: The spray-dried microspheres are placed in a tube furnace and calcined at a constant temperature in an air atmosphere. After cooling in the furnace, they are taken out to obtain the modified crude oil catalytic cracking enhancement agent.

8. A mixture of catalytic cracking catalysts, characterized in that, Includes the modified crude oil catalytic cracking enhancer as described in any one of claims 1 to 6 and commercially available REY catalysts.

9. The catalytic cracking catalyst mixture as described in claim 8, characterized in that, The mass ratio of the modified crude oil catalytic cracking enhancer to the commercially available REY catalyst is (3~15):(85~97).

10. The method of applying the catalytic cracking catalyst mixture according to any one of claims 8 to 9, characterized in that, The process includes the following steps: loading the mixed catalyst into a catalytic cracking reactor, and operating at a reaction temperature of 500-540°C, a catalyst-to-oil ratio of 5.0-8.0, and a weight hourly space velocity of 10-20 h⁻¹. -1 Under certain conditions, the catalyst undergoes catalytic cracking reaction in contact with crude oil feedstock. The reaction products are fractionated to obtain dry gas, liquefied petroleum gas, gasoline, diesel, and heavy oil fractions. The catalyst is stripped and then enters the regenerator for coking and regeneration at 680~720℃ in an air atmosphere. After regeneration, the catalyst is returned to the reactor for recycling.

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