Emulsion type catalyst for hydrothermal cracking of thickened oil as well as preparation method and application of emulsion type catalyst

Abstract

The invention discloses an emulsion type catalyst for hydrothermal cracking of thickened oil as well as a preparation method and application of the emulsion type catalyst, and belongs to the technical field of oil exploitation and catalysis. The catalyst is prepared by the following method: adding a molybdenum-based catalyst, an emulsifier and emulsion oil into water, and carrying out ultrasonic emulsification to obtain the thick oil hydrothermal cracking emulsion type catalyst. The emulsion type catalyst prepared by the invention is a nano molybdenum catalytic system with high stability, low oil phase proportion, wide pH application range and good salt tolerance, has good dispersity and transmission capacity in an oil-water reaction system, has relatively high catalytic cracking activity on underground thickened oil, and can be used for preparing the underground thickened oil. Therefore, the method has good applicability and good application value in the technical field of oil exploitation.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction and catalysis technology, specifically relating to an emulsion catalyst for hydrothermal cracking of heavy oil, its preparation method and application. Background Technology

[0002] For deep heavy oil reservoirs with vast reserves, efficient and rapid extraction methods have become a global research focus. However, heavy oil itself is rich in long-chain and cyclic polycyclic compounds such as gums and asphaltenes, giving it characteristics of high relative density, poor fluidity, and high viscosity. Furthermore, the complex reservoir environment presents numerous challenges during heavy oil extraction and transportation. In-situ catalytic upgrading of heavy oil can introduce catalysts into the reservoir to catalyze in-situ heavy oil cracking, thereby reducing viscosity and density, enhancing oil fluidity, and improving recovery rates. This method is considered a key direction for future heavy oil extraction because it minimizes environmental impact and energy consumption. However, existing heavy oil hydrothermal cracking catalysts suffer from drawbacks such as insufficient catalytic activity, poor system stability, high oil phase content, limited environmental adaptability, and low dispersion and transfer efficiency in oil-water reaction systems. Therefore, providing an emulsion-type heavy oil hydrothermal cracking catalyst with high catalytic activity, low oil phase content, high stability, wide pH adaptability, and good salt tolerance is of great significance. Summary of the Invention

[0003] This invention provides an emulsion catalyst for hydrothermal cracking of heavy oil, which is prepared by adding a molybdenum-based catalyst, an emulsifier, and an emulsion oil to water and ultrasonically emulsifying them to obtain a hydrothermal cracking emulsion catalyst for heavy oil.

[0004] In the above method for preparing emulsion catalysts, the raw materials are selected from the following parts by mass: 0.005~0.1 parts of molybdenum-based catalyst, 0.1~0.5 parts of emulsifier, 1~10 parts of emulsion oil, and 10~50 parts of water.

[0005] In the above method for preparing emulsion catalysts, the amount of emulsifier used is 0.1 to 0.5% of the total mass of the emulsion catalyst.

[0006] In the above-mentioned method for preparing emulsion catalysts, the amount of emulsion oil is 5-20% of the total mass of the emulsion catalyst, preferably 8-15%, and more preferably 10%, so that while maintaining low oil phase usage and solvent cost, the emulsion system can still have high stability and good dispersion performance.

[0007] In the above method for preparing emulsion catalysts, the emulsifier is at least one of sodium dodecylbenzenesulfonate, saponin, and sodium hexadecylbenzenesulfonate.

[0008] In the above method for preparing emulsion catalysts, the emulsion oil is at least one of n-heptane, industrial white oil, and diesel oil.

[0009] In the above method for preparing emulsion catalysts, the conditions for ultrasonic emulsification are: ultrasonic emulsification at 100~200W for 10~20min.

[0010] In the above-described method for preparing emulsion-type catalysts, the molybdenum-based catalyst is prepared by the following method: A molybdenum-containing precursor, a sulfur source, and a morphology modifier were added to water, stirred to dissolve, and then subjected to a hydrothermal reaction. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain a molybdenum-based catalyst.

[0011] In the above method for preparing molybdenum-based catalysts, the molybdenum-containing precursor is at least one of molybdenum trioxide, ammonium molybdate, and ammonium tetrathiomolybdate.

[0012] In the above method for preparing molybdenum-based catalysts, the sulfur source is at least one of thiourea and sodium sulfide.

[0013] In the above method for preparing molybdenum-based catalysts, the morphology modifier is at least one of polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, and ethylenediamine.

[0014] In the above method for preparing molybdenum-based catalysts, the raw materials are selected from the following parts by mass: 0.1 to 1 part of molybdenum-containing precursor, 0.1 to 5 parts of sulfur source, 0.1 to 1 part of morphology modifier, and 50 to 200 parts of water.

[0015] In the above method for preparing molybdenum-based catalysts, the hydrothermal reaction conditions are: reaction at 150~200℃ for 10~24h.

[0016] This invention provides the application of the above-mentioned emulsion catalyst in in-situ underground upgrading and viscosity reduction of heavy oil.

[0017] This invention provides a method for in-situ underground modification and viscosity reduction of heavy oil, the steps of which are as follows: An emulsion catalyst and a hydrogen donor, tetrahydronaphthalene, are injected into underground heavy oil. The pressure is maintained at 1~1.5MPa, the temperature is raised to 180~250℃, and the reaction is continuously stirred at 100~150 r / min for 18~36h to achieve in-situ underground upgrading and viscosity reduction of heavy oil.

[0018] In the above-mentioned in-situ underground upgrading and viscosity reduction methods for heavy oil, based on 100 wt% of heavy oil, the amount of emulsion catalyst is 20-40 wt%, and the amount of hydrogen donor tetrahydronaphthalene is 1-2 wt%.

[0019] The beneficial effects of this invention are as follows: This invention, through the synergistic design of pre-fabricated molybdenum-based catalyst particles and emulsion dispersion, improves the effective contact efficiency of the catalyst at the oil-water reaction interface and the dispersion stability in the reaction system, thereby significantly enhancing the catalytic activity and upgrading effect of heavy oil hydrothermal cracking. The emulsion catalyst can catalytically crack asphaltenes and aromatics in heavy oil at 180–250 °C and 1.0–1.5 MPa, significantly reducing the viscosity of heavy oil, thus demonstrating good applicability and application value in the field of petroleum extraction technology.

[0020] The emulsion catalyst prepared in this invention is a nano-molybdenum catalytic system with high stability, low oil phase ratio, wide pH range and good salt resistance. It has good dispersibility and transport ability in oil-water reaction system and high catalytic cracking activity for underground heavy oil.

[0021] The molybdenum-based nanoparticles in the emulsion-type heavy oil hydrothermal pyrolysis catalyst prepared in this invention are characterized by small particle size, high dispersibility, and relatively uniform size, providing good catalytic pyrolysis performance. Simultaneously, the emulsion-type catalyst employs a low-oil-phase design, reducing the amount of light oil phase used while ensuring the stability of the emulsion system, thereby lowering the solvent oil cost during catalyst injection. Furthermore, the emulsion-type catalyst exhibits good stability over a wide pH range and maintains good emulsification stability and dispersion performance at certain salt concentrations, making it more suitable for in-situ underground upgrading processes of heavy oil in complex formation environments. Attached Figure Description

[0022] Figure 1 The image shows the XRD pattern of a heavy oil hydrothermal pyrolysis emulsion catalyst.

[0023] Figure 2 This is a SEM image of a heavy oil hydrothermal pyrolysis emulsion catalyst.

[0024] Figure 3 The appearance (1) of emulsion catalysts with different emulsion oil phase ratios and the microstructure (2) of emulsion catalysts with 10wt% emulsion oil content are shown in Figure (1). In Figure (1), 1 to 8 are 1wt%, 3wt%, 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, and 50wt% respectively. In Figure (2), the white scale bar is 100nm.

[0025] Figure 4 The appearance and microstructure of the emulsion catalyst under different pH and NaCl concentrations are shown, with the white scale bar representing 100 nm.

[0026] Figure 5 This is a characterization diagram of the interface structure of the emulsion catalyst of the present invention, where the white scale bar is 100 nm. Detailed Implementation

[0027] In this invention, No. 0 diesel oil comes from Sinopec; commercially available molybdenum-based catalyst powder (ZY-MoS2-N80) comes from Beasley New Materials (Suzhou); Shengli heavy oil is crude oil sample from Zheng-411 block of Shengli Oilfield of Sinopec; marine heavy oil is crude oil sample from Luda 5-2 North Block of CNOOC Tianjin Branch.

[0028] Other materials used in this invention, unless otherwise stated, are commercially available. Other terms used in this invention, unless otherwise specified, generally have the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. The following embodiments are merely illustrative and not intended to limit the scope of the invention in any way. Example 1

[0029] The steps for preparing a heavy oil hydrothermal pyrolysis emulsion catalyst are as follows: At room temperature, 0.35 g ammonium molybdate tetrahydrate, 0.76 g thiourea, and 0.2 g polyvinylpyrrolidone were dissolved in 80 g deionized water and stirred for 1 h to form a molybdenum precursor suspension. The molybdenum precursor suspension was then added to a 250 mL hydrothermal synthesis reactor and reacted in an oven at 180 °C for 12 h. The mixture was then centrifuged at 12000 r / min for 15 min, washed three times alternately with deionized water and ethanol, and freeze-dried for 48 h to obtain a molybdenum-based catalyst powder. 0.02 g of the molybdenum-based catalyst powder, 0.15 g sodium dodecylbenzenesulfonate, and 3 g n-heptane were added to 27 g deionized water, and the mixture was ultrasonically emulsified at 150 W for 15 min to obtain a heavy oil hydrothermal pyrolysis emulsion catalyst.

[0030] The heavy oil hydrothermal pyrolysis emulsion catalyst prepared in Example 1 was characterized by SEM and XRD diffraction. The XRD pattern is shown below. Figure 1 As shown, the catalyst exhibits typical characteristic peaks of molybdenum disulfide, including (002), (100), and (110) crystal forms. SEM test results are as follows... Figure 2 As shown, by Figure 2 It can be seen that the synthesized heavy oil hydrothermal pyrolysis emulsion catalyst has a small particle size (<500nm) and exhibits a monodisperse state. Example 2

[0031] The steps for preparing a heavy oil hydrothermal pyrolysis emulsion catalyst are as follows: At room temperature, 0.5 g ammonium tetrathiomolybdate, 0.38 g thiourea, and 0.25 g polyvinylpyrrolidone were dissolved in 80 g deionized water and stirred for 1 h to form a molybdenum precursor suspension. The molybdenum precursor suspension was then added to a 250 mL hydrothermal synthesis reactor and reacted in an oven at 200 °C for 16 h. After centrifugation at 12000 r / min for 20 min, the mixture was washed three times alternately with deionized water and ethanol, and then vacuum dried at 80 °C for 24 h to obtain a molybdenum-based catalyst powder. 0.02 g of the molybdenum-based catalyst powder, 0.2 g of saponin, and 4 g of industrial white oil were added to 26 g of deionized water, and the mixture was ultrasonically emulsified at 150 W for 15 min to obtain a heavy oil hydrothermal pyrolysis emulsion catalyst. Example 3

[0032] The steps for preparing a heavy oil hydrothermal pyrolysis emulsion catalyst are as follows: At room temperature, 0.18 g of molybdenum trioxide, 0.78 g of sodium sulfide, and 0.25 g of cetyltrimethylammonium bromide were dissolved in 80 g of deionized water and stirred for 0.5 h to form a molybdenum precursor suspension. The molybdenum precursor suspension was then added to a 250 mL hydrothermal synthesis reactor and reacted in an oven at 150 °C for 24 h. The mixture was then centrifuged at 10000 r / min for 20 min, washed three times alternately with deionized water and ethanol, and vacuum dried at 80 °C for 24 h to obtain a molybdenum-based catalyst powder. 0.02 g of the molybdenum-based catalyst powder, 0.2 g of sodium cetylbenzenesulfonate, and 2.5 g of No. 0 diesel oil were added to 27.5 g of deionized water, and the mixture was ultrasonically emulsified at 200 W for 15 min to obtain a heavy oil hydrothermal pyrolysis emulsion catalyst.

[0033] Comparative Example 1 (without emulsion oil) The steps for preparing a heavy oil hydrothermal pyrolysis catalyst are as follows: At room temperature, 0.5 g ammonium tetrathiomolybdate, 0.38 g thiourea, and 0.25 g polyvinylpyrrolidone were dissolved in 80 g deionized water and stirred for 1 h to form a molybdenum precursor suspension. The molybdenum precursor suspension was then added to a 250 mL hydrothermal synthesis reactor and reacted in an oven at 200 °C for 16 h. The mixture was then centrifuged at 12000 r / min for 20 min, washed three times alternately with deionized water and ethanol, and vacuum dried at 80 °C for 24 h to obtain a molybdenum-based catalyst powder. 0.02 g of the molybdenum-based catalyst powder and 0.2 g of saponin were added to 26 g of deionized water, and the mixture was ultrasonically emulsified at 150 W for 15 min to obtain a heavy oil hydrothermal pyrolysis emulsion catalyst.

[0034] Comparative Example 2 (using commercially available molybdenum-based catalyst directly) The steps for preparing a heavy oil hydrothermal pyrolysis catalyst are as follows: 0.02 g of commercially available molybdenum-based catalyst powder (ZY-MoS2-N80), 0.2 g of sodium cetylbenzenesulfonate, and 2.5 g of No. 0 diesel oil were added to 27.5 g of deionized water and ultrasonically emulsified at 200 W for 15 min to obtain a heavy oil hydrothermal cracking catalyst.

[0035] Comparative Example 3 (without molybdenum-based catalyst) The steps for preparing a heavy oil hydrothermal pyrolysis emulsion are as follows: Add 0.15 g sodium dodecylbenzenesulfonate and 3 g n-heptane to 27 g deionized water, and ultrasonically emulsify at 150 W for 15 min to obtain a heavy oil hydrothermal pyrolysis emulsion.

[0036] I. Hydrothermal Catalytic Cracking Experiment Take 70g of Shengli heavy oil or marine heavy oil, add 19g of water, 10g of catalyst and 1g of tetrahydronaphthalene (hydrogen donor), seal the autoclave, purge with nitrogen to 1MPa to replace the air, then heat to 250℃ and stir for 20h to carry out hydrothermal pyrolysis reaction.

[0037] The viscosity of the oil sample was determined using a rheometer (Anton Paar MCR 302). 3 g of oil sample was uniformly coated onto the test plate. The test temperature was set at 40°C, and the cooling rate was 1°C / s.

[0038] The formula for calculating viscosity reduction rate is as follows: ; in, η represents the viscosity reduction rate of heavy oil, η0 represents the initial viscosity of crude oil, and η represents the viscosity of heavy oil after hydrothermal cracking.

[0039] The test results are shown in Table 1: Table 1. Viscosity Reduction Effect of Various Catalysts on Heavy Oil Note: In Table 1 above, Comparative Example 4 is based on Example 1, but no hydrogen donor was added during the hydrothermal catalytic cracking experiment.

[0040] II. Low oil phase emulsion stability To investigate the effect of the oil phase ratio on the stability of emulsion catalysts, emulsion catalysts with different oil phase ratios were prepared by adjusting the content of n-heptane in Example 1 (1 wt%, 3 wt%, 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%) while keeping the total mass of the system constant. The morphology of each emulsion catalyst was observed, and the microstructure of the emulsion catalyst with a n-heptane content of 10 wt% was characterized.

[0041] The results are as follows Figure 3 As shown: Depend on Figure 3 It is known that when the proportion of the oil phase in the emulsion is too low, such as 1 wt%, 3 wt%, or 5 wt%, the system stability decreases, and demulsification is likely to occur after standing for 21 days. When the oil phase content of the emulsion is 10 wt%, the emulsion system maintains a good dispersion and stability. Using 10 wt% emulsion oil is still considered a low oil phase design compared to oil-soluble catalysts. Therefore, this invention can obtain an emulsion catalyst with good stability while reducing the amount of oil phase and solvent costs.

[0042] III. pH adaptability and salt tolerance To investigate the stability of the emulsion catalyst under different environmental conditions, the appearance, microstructure and particle size distribution of the emulsion catalyst prepared in Example 1 were characterized under different pH and different NaCl concentrations.

[0043] Test results are as follows Figure 4 As shown: The emulsion catalyst maintains good emulsification and droplet dispersibility within a pH range of 2-9, indicating that it has a wide pH adaptability range. At the same time, when the NaCl concentration is not higher than 500 mM, the emulsion system still maintains good stability and particle dispersion performance, indicating that the emulsion catalyst of the present invention has good salt resistance and can adapt to complex formation conditions.

[0044] IV. Structural Characteristics of Emulsions To further verify the emulsion structure characteristics of the emulsion catalyst of the present invention, n-heptane in Example 1 was replaced with 1,6-hexanediol diacrylate, and photoinitiator 1173 was added to cure the colloidal droplets for SEM observation.

[0045] Emulsions are inherently thermodynamically unstable liquid-liquid dispersions, and their interfacial structures (including droplet size, interfacial layer thickness, and catalyst distribution) are highly susceptible to rearrangement under external disturbances. The oil phase in the original system is n-heptane, which is prone to volatilization and droplet collapse during conventional SEM sample preparation processes (such as drying and vacuum environments), leading to emulsion structural damage and failing to accurately reflect the original microstructure of the oil-water interface. Therefore, directly observing untreated emulsions using SEM is insufficient to obtain reliable structural information.

[0046] The oil phase was replaced with 1,6-hexanediol diacrylate (HDDA), and photoinitiator 1173 was added. After the emulsion was formed, the 1,6-hexanediol diacrylate was polymerized in situ by UV light, which caused rapid cross-linking and solidification inside the droplets to form a hard polymer shell. This transformed the dynamic emulsion droplets into a solid microsphere structure and preserved the original oil-water interface morphology and size distribution to the greatest extent.

[0047] The results are as follows Figure 5 As shown: The clean and smooth surface of the microspheres indicates that no MoS2 nanoparticles were adsorbed at the oil-water interface. This demonstrates that the emulsion catalyst formed a stable emulsion system, and the molybdenum-based catalyst particles exhibited good dispersibility within the system.

[0048] In summary, this invention constructs a stable emulsion-type catalytic system through a synergistic design of "molybdenum-based catalyst particle prefabrication-emulsion dispersion," which is beneficial for the uniform dispersion of the catalyst in the oil-water reaction system and its effective contact with heavy oil components.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An emulsion catalyst for hydrothermal cracking of heavy oil, characterized in that, The catalyst is prepared by adding a molybdenum-based catalyst, an emulsifier, and an emulsion oil to water and ultrasonically emulsifying them to obtain a heavy oil hydrothermal pyrolysis emulsion catalyst.

2. The emulsion catalyst for hydrothermal cracking of heavy oil according to claim 1, characterized in that, The raw materials are selected from the following parts by weight: 0.005~0.1 parts of molybdenum-based catalyst, 0.1~0.5 parts of emulsifier, 1~10 parts of emulsion oil, and 10~50 parts of water.

3. The emulsion catalyst for hydrothermal cracking of heavy oil according to claim 1, characterized in that, The emulsifier is at least one of sodium dodecylbenzenesulfonate, saponin, and sodium hexadecylbenzenesulfonate; the emulsion oil is at least one of n-heptane, industrial white oil, and diesel oil.

4. The emulsion catalyst for heavy oil hydrothermal cracking according to claim 1, characterized in that, The conditions for ultrasonic emulsification are: 100~200W ultrasonic emulsification for 10~20 minutes.

5. The emulsion catalyst for hydrothermal cracking of heavy oil according to claim 1, characterized in that, The molybdenum-based catalyst is prepared by the following method: A molybdenum-containing precursor, a sulfur source, and a morphology modifier were added to water, stirred to dissolve, and then subjected to a hydrothermal reaction. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain a molybdenum-based catalyst.

6. The emulsion catalyst for heavy oil hydrothermal cracking according to claim 5, characterized in that, The molybdenum-containing precursor is at least one of molybdenum trioxide, ammonium molybdate, and ammonium tetrathiomolybdate; the sulfur source is at least one of thiourea and sodium sulfide; and the morphology modifier is at least one of polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, and ethylenediamine.

7. The emulsion catalyst for heavy oil hydrothermal cracking according to claim 5, characterized in that, The raw materials are selected from the following parts by weight: 0.1 to 1 part of molybdenum precursor, 0.1 to 5 parts of sulfur source, 0.1 to 1 part of morphology modifier, and 50 to 200 parts of water.

8. The emulsion catalyst for heavy oil hydrothermal cracking according to claim 5, characterized in that, The hydrothermal reaction conditions are: reaction at 150~200℃ for 10~24h.

9. The application of the emulsion catalyst according to any one of claims 1 to 8 in in-situ underground upgrading and viscosity reduction of heavy oil.

10. A method for in-situ underground modification and viscosity reduction of heavy oil, characterized in that, The steps are as follows: The emulsion catalyst and hydrogen donor described in any one of claims 1 to 8 are injected into underground heavy oil, the pressure is maintained at 1 to 1.5 MPa, the temperature is raised to 180 to 250°C, and the reaction is continuously stirred at 100 to 150 r / min for 18 to 36 hours to achieve in-situ underground upgrading and viscosity reduction of heavy oil.

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