Flaky zinc oxide particles, preparation method and application thereof and foam system

Abstract

The invention provides flaky zinc oxide particles and a preparation method, application and foam system.The preparation method comprises the steps that a zinc salt aqueous solution and a citric acid / sodium citrate mixed aqueous solution are evenly mixed, alkali liquor is added, then a urea aqueous solution is added, and a mixed solution is obtained; carrying out hydrothermal reaction on the mixed solution; and filtering the suspension obtained after the reaction to obtain a filtered substance, and sequentially washing and drying the filtered substance to obtain the flaky zinc oxide particles. According to the invention, the zinc oxide particles with regular hexagonal sheet structures are prepared from zinc salt, alkali and urea through a hydrothermal synthesis method for the first time. The prepared zinc oxide particles are of a regular hexagonal sheet structure, have the characteristics of high specific surface area, good foam stability, temperature resistance, salt resistance, good compatibility with formation water and the like, can be applied to a foam flooding technology for improving the crude oil recovery rate of a high-temperature and high-salt oil reservoir, and have a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to a sheet-like zinc oxide particle, its preparation method, application, and foam system, belonging to the field of petroleum extraction technology. Background Technology

[0002] Foam-based enhanced oil recovery (EOR) technology combines the ability to expand swept volume and improve oil displacement efficiency. It effectively improves reservoir heterogeneity and enhances oil recovery, making it a highly promising tertiary oil recovery technology. However, foam is a thermodynamically unstable system, requiring the addition of foam stabilizers to enhance its stability. Solid particles can effectively adsorb onto the foam liquid film, forming a thin film containing solid particles. This film slows down the drainage rate between the liquid films, inhibits gas diffusion, prolongs the foam's half-life, and improves its stability. Adding solid particles to the foam system enhances foam performance and improves oil recovery; the smaller the particle size and the larger the specific surface area of ​​the solid particles, the more significant the foam stabilizing effect.

[0003] Currently, the main methods for preparing zinc oxide in this field include hydrothermal synthesis, solvothermal synthesis, precipitation, green synthesis, and sol-gel methods. Among these, the solvothermal and precipitation methods involve high reaction temperatures and require sophisticated experimental equipment, while the green synthesis and sol-gel methods involve complex processes and long reaction times, making them difficult to meet the requirements of industrial production.

[0004] Therefore, researching, developing, and providing a novel type of sheet-like zinc oxide particles, its preparation method, applications, and foaming system has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned shortcomings and deficiencies, the present invention aims to provide a sheet-like zinc oxide particle, its preparation method, application, and foam system.

[0006] To achieve the above objectives, on the one hand, the present invention provides a method for preparing flake-shaped zinc oxide particles, wherein the preparation method includes:

[0007] Step (1): Mix the zinc salt aqueous solution and the citric acid / sodium citrate mixed aqueous solution evenly, add the alkali solution, and then add the urea aqueous solution to obtain a mixed solution;

[0008] Step (2): Allow the mixed solution to undergo a hydrothermal reaction;

[0009] Step (3): Filter the suspension obtained after the reaction in step (2) to obtain the filter material, and then wash and dry the filter material in sequence to obtain flaky zinc oxide particles.

[0010] In the reaction system involved in the preparation method described above in this invention, divalent zinc ions react with hydroxide ions in the solution to generate zinc hydroxide. The zinc hydroxide continues to react at a set hydrothermal reaction temperature, finally forming zinc oxide precipitate. The main reaction equations involved in the reaction system include:

[0011] Zn 2+ +2OH - →Zn(OH)2;

[0012] Zn(OH)₂ + 2H₂O → Zn(OH)₄ 2- +2H + ;

[0013] Zn(OH)4 2- →ZnO + H₂O + 2OH⁻ - .

[0014] In one specific embodiment of the preparation method described above in this invention, in step (1), the molar ratio of zinc salt, citric acid, sodium citrate, and urea is 10-50:1:50. In some specific embodiments of this invention, in step (1), the volume ratio of the zinc salt aqueous solution, the citric acid / sodium citrate mixed aqueous solution, and the urea aqueous solution can be, for example, 50:1:50, and the concentrations of the zinc salt aqueous solution, the citric acid / sodium citrate mixed aqueous solution, and the urea aqueous solution can be, for example, 0.1 mol / L, 0.2 mol / L, and 0.2 mol / L, respectively.

[0015] This invention does not impose specific requirements on the ratio of citric acid to sodium citrate in the citric acid / sodium citrate mixed aqueous solution. The ratio can be reasonably selected and adjusted as needed, as long as the objective of this invention is achieved. For example, in some specific embodiments of this invention, the molar ratio of citric acid to sodium citrate can be 1:1.

[0016] As a specific embodiment of the preparation method described above in this invention, in step (1), the zinc salt includes any one or more of zinc acetate, zinc chloride, zinc sulfate and zinc nitrate, preferably zinc nitrate.

[0017] As a specific embodiment of the preparation method described above in this invention, in step (1), an alkaline solution is added to adjust the pH value of the system to 6.6-6.9.

[0018] As a specific embodiment of the preparation method described above in this invention, in step (1), the concentration of the alkaline solution is 2 mol / L.

[0019] As a specific embodiment of the preparation method described above in this invention, in step (1), the alkaline solution includes any one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution and ammonia solution, preferably sodium hydroxide aqueous solution.

[0020] In one specific embodiment of the preparation method described above in this invention, in step (2), the temperature of the hydrothermal reaction is 120-140℃, and the time is 160-200 min. In a more preferred embodiment of this invention, the hydrothermal reaction can be carried out under stirring conditions, and this invention does not impose specific requirements on the stirring speed, which can be reasonably adjusted as needed. For example, in some specific embodiments of this invention, the stirring speed can be 800 r / min.

[0021] On the other hand, the present invention also provides a sheet-like zinc oxide particle, which is prepared by the above-described method for preparing sheet-like zinc oxide particles, wherein the sheet-like zinc oxide particles have a regular hexagonal sheet-like structure.

[0022] As a specific embodiment of the above-described flaky zinc oxide particles of the present invention, the particle size of the flaky zinc oxide particles is about 10-90 μm, preferably about 10-30 μm.

[0023] In another aspect, the present invention also provides the application of the above-described flaky zinc oxide particles as a foam stabilizer.

[0024] In another aspect, the present invention also provides a foam system comprising a foam stabilizer and a foaming agent, wherein the foam stabilizer is the above-described flaky zinc oxide particles.

[0025] Compared with the prior art, the beneficial technical effects achieved by the present invention include at least the following:

[0026] This invention, for the first time, utilizes a hydrothermal synthesis method involving zinc salts, alkali, and urea to prepare zinc oxide particles with a regular hexagonal plate-like structure. The preparation method is simple, quick, and easy to operate, with mild reaction conditions, short reaction time, low requirements for experimental equipment (i.e., simple experimental equipment), and high purity of the obtained product. The prepared zinc oxide particles exhibit a regular hexagonal plate-like structure, possessing characteristics such as high specific surface area, good foam stability, temperature and salt resistance, and good compatibility with formation water. It is suitable for foam flooding technology to enhance oil recovery in high-temperature, high-salinity oil reservoirs, and has promising industrial application prospects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1The image shows the XRD diffraction pattern of the product ZnO-P1 obtained in Example 1 of this invention.

[0029] Figure 2a and Figure 2b This is a scanning electron microscope image of the product ZnO-P1 obtained in Example 1 of the present invention.

[0030] Figure 3 This is a particle size distribution diagram of the product ZnO-P1 obtained in Example 1 of the present invention. Detailed Implementation

[0031] It should be noted that the term "comprising" and any variations thereof in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0032] The "range" disclosed in this invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges defined in this way are composable, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is also expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if the listed minimum range values ​​are 1 and 2, and the listed maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0033] In this invention, unless otherwise specified, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this invention, and "0-5" is simply a shortened representation of these numerical combinations.

[0034] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in this invention can be combined with each other to form new technical solutions.

[0035] In this invention, unless otherwise specified, all technical features and preferred features mentioned in this invention can be combined with each other to form new technical solutions.

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to tables, drawings, and embodiments. The embodiments described below are some, but not all, embodiments of this invention, and are only used to illustrate the invention, and should not be considered as limiting the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0037] Example 1

[0038] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0039] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0040] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.6 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0041] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0042] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P1.

[0043] The ZnO-P1 product obtained in this embodiment was subjected to XRD diffraction analysis. After the test, the positions of the diffraction peaks of the ZnO-P1 product and the standard diffraction characteristic peaks of zinc oxide were compared to determine whether the product ZnO-P1 was zinc oxide and whether it contained other impurities. The XRD diffraction pattern of the ZnO-P1 product obtained in Example 1 of this invention is shown below. Figure 1As shown, from Figure 1 As can be seen from the data, each peak is a characteristic peak of zinc oxide, and there are no characteristic peaks of other impurities, which proves that the ZnO-P1 product obtained in Example 1 has excellent purity.

[0044] The ZnO-P1 product obtained in this embodiment was further subjected to vacuum scanning electron microscopy (SEM) testing to observe its microstructure and size. The SEM image of the ZnO-P1 product obtained in Example 1 of this invention is shown below. Figure 2a and Figure 2b As shown, from Figure 2a and Figure 2b As can be seen, the products are all hexagonal sheet-like structures.

[0045] The particle size distribution diagram of the ZnO-P1 product obtained in this embodiment is as follows: Figure 3 As shown. From Figure 3 As can be seen from the data, the average particle size of the ZnO-P1 product obtained in this embodiment is around 10 μm.

[0046] In summary, the XRD analysis and scanning electron microscopy results prove that the product ZnO-P1 obtained in this embodiment is a high-purity zinc oxide particle with a hexagonal plate-like structure and an average particle size of about 10 μm.

[0047] Example 2

[0048] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0049] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0050] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.9 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0051] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 140 ℃ and the stirring speed to 800 r / min, and react under these conditions for 160 min. After the reaction is completed, let the vessel cool to room temperature.

[0052] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P2.

[0053] The ZnO-P2 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P2 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure and an average particle size of about 20 μm.

[0054] Example 3

[0055] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0056] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0057] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.6 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0058] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 120 ℃ and the stirring speed to 800 r / min, and react under these conditions for 200 min. After the reaction is completed, let the vessel cool to room temperature.

[0059] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P3.

[0060] The ZnO-P3 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P3 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure and an average particle size of about 15 μm.

[0061] Example 4

[0062] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0063] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 50 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0064] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.6 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0065] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0066] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P4.

[0067] The ZnO-P4 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P4 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure and an average particle size of about 25 μm.

[0068] Example 5

[0069] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0070] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 150 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0071] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.6 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0072] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0073] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P5.

[0074] The ZnO-P5 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P5 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure and an average particle size of about 30 μm.

[0075] Example 6

[0076] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0077] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0078] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.0 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0079] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0080] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P6.

[0081] The ZnO-P6 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P6 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure, but its average particle size is about 35 μm.

[0082] Example 7

[0083] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0084] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0085] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 7.1 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0086] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0087] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P7.

[0088] The ZnO-P7 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P7 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure, but its average particle size is about 50 μm.

[0089] Example 8

[0090] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0091] Step (1): Take commercially available zinc nitrate hexahydrate, urea, potassium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc nitrate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L potassium hydroxide aqueous solution with deionized water.

[0092] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.6 with potassium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0093] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0094] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P8.

[0095] The ZnO-P8 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P8 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure and an average particle size of about 40 μm.

[0096] Example 9

[0097] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0098] Step (1): Take commercially available zinc nitrate hexahydrate, urea, sodium citrate and citric acid, all with a purity of 100%. Take a certain amount of ammonia solution and prepare 100 mL of zinc nitrate solution with a concentration of 0.1 mol / L, 2 mL of citric acid / sodium citrate mixed solution with a concentration of 0.2 mol / L, and the molar ratio of citric acid and sodium citrate is 1:1, 100 mL of urea solution with a concentration of 0.2 mol / L, and 2 mol / L ammonia solution with a concentration of 2 mol / L.

[0099] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc nitrate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.9 with ammonia solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0100] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0101] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P9.

[0102] The ZnO-P9 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P9 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure, but its average particle size is as high as about 70 μm.

[0103] Example 10

[0104] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0105] Step (1): Take commercially available zinc acetate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 100 mL of 0.1 mol / L zinc acetate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0106] At room temperature, add a citric acid / sodium citrate mixed solution to a zinc acetate aqueous solution, stir and mix thoroughly, then adjust the pH of the system to 6.6 with sodium hydroxide aqueous solution, stir at room temperature for 1 h, and then slowly add urea aqueous solution dropwise to the mixed solution, controlling the dropwise addition rate to about 60 mL / h.

[0107] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0108] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P10.

[0109] The ZnO-P10 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P10 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure, but its average particle size is as high as about 90 μm.

[0110] Example 11

[0111] This embodiment provides a method for preparing flaky zinc oxide particles, wherein the preparation method includes the following specific steps:

[0112] Step (1): Take commercially available zinc chloride, zinc sulfate, urea, sodium hydroxide, sodium citrate and citric acid, all with a purity of 100%. Prepare 50 mL of 0.1 mol / L zinc chloride aqueous solution, 50 mL of 0.1 mol / L zinc sulfate aqueous solution, 2 mL of 0.2 mol / L citric acid / sodium citrate mixed aqueous solution with a molar ratio of 1:1, 100 mL of 0.2 mol / L urea aqueous solution and 2 mol / L sodium hydroxide aqueous solution with deionized water.

[0113] At room temperature, 50 mL of 0.1 mol / L zinc chloride aqueous solution and 50 mL of 0.1 mol / L zinc sulfate aqueous solution were mixed evenly to obtain a mixed solution. Citric acid / sodium citrate mixed solution was added to the mixed solution and stirred evenly. The pH value of the system was adjusted to 6.6 with sodium hydroxide aqueous solution and stirred at room temperature for 1 h. Then, urea aqueous solution was slowly added dropwise to the mixed solution, and the dropping rate was controlled at about 60 mL / h.

[0114] Step (2): After the addition is complete, transfer the solution into the reaction vessel, set the temperature to 130 ℃ and the stirring speed to 800 r / min, and react under these conditions for 180 min. After the reaction is completed, let the vessel cool to room temperature.

[0115] Step (3): After the reaction in step (2) is completed, the suspension obtained is filtered to obtain the filter material. Then, the filter material is thoroughly washed with anhydrous ethanol under ultrasonic conditions and dried to obtain the product, flaky zinc oxide particles, denoted as ZnO-P11.

[0116] The ZnO-P11 product obtained in this embodiment was subjected to XRD diffraction analysis and vacuum scanning electron microscopy analysis. The XRD analysis and scanning electron microscopy results confirmed that the ZnO-P11 product obtained in this embodiment is also a high-purity zinc oxide particle with a hexagonal plate-like structure, but its average particle size is about 60 μm.

[0117] Test Example 1

[0118] This test example tested the foam stability of the flake-shaped zinc oxide particles prepared in Examples 1-11 of the present invention when used as foam stabilizers. The specific test steps are as follows:

[0119] Produced water from the Abu Dhabi reservoir in the Middle East (with a total salinity of 217308.72 mg / L, of which Ca...) was used. 2+ Mg 2+ Prepare 200g of foaming solution containing a certain concentration of foam stabilizer and foaming agent (with a total divalent ion content of 19940mg / L). Seal the foaming solution and place it in an oven at 90℃ (corresponding to the target reservoir temperature) for 30 minutes. Stir for 1 minute using a WARING stirrer (approximately 7000 rpm). Immediately pour the solution into a 2000mL graduated cylinder, seal it with plastic wrap, and start timing. Record the volume of foam when stirring stops, denoted as V (V is called the foam volume, mL), and the time t required to separate 100mL of liquid from the foam. 1 / 2 (t) 1 / 2 This is called the foam separation half-life, or simply half-life (s). The foaming capacity is represented by the foaming volume V, expressed in tons (t). 1 / 2This indicates the stability of the foam. A larger V indicates a stronger foaming ability of the foaming liquid. 1 / 2 The larger the value, the better the stability of the bubble.

[0120] This test case evaluated and compared the foam volume and foam separation half-life of different foaming solutions (denoted as foaming solution 1 to foaming solution 11) composed of the biosurfactant sodium alkyl glycoside sulfonate (APGS) foaming agent, biopolysaccharide polymer (WP2101) foam stabilizer, and flake zinc oxide granule foam stabilizers (ZnO-P1, ZnO-P2, ZnO-P3, ZnO-P3, ZnO-P5, ZnO-P6, ZnO-P7, ZnO-P8, ZnO-P9, ZnO-P10, ZnO-P11, respectively). The results are shown in Table 1 below.

[0121] Table 1

[0122]

[0123] Note: The foaming fluid formulation system in Table 1 includes, in addition to the components shown in the table, the remaining amount of produced water from the Abu Dhabi oil reservoir in the Middle East. The content of each component in the foaming fluid formulation system is by weight percentage, which is calculated based on the total weight of the foaming fluid formulation system.

[0124] As shown in Table 1, the foaming abilities of the 12 groups of foaming solutions are similar. This indicates that the flake zinc oxide particles prepared in the embodiments of the present invention have good compatibility with the biosurfactant sodium alkyl glycoside sulfonate (APGS) foaming agent, the biopolysaccharide polymer (WP2101) foaming stabilizer, and the produced water from the Abu Dhabi oil reservoir in the Middle East when used as a foam stabilizer. Furthermore, it has excellent temperature and salt resistance. However, a further comparison of the foaming abilities of the 12 groups of foaming solutions shows that the foaming abilities of foaming solutions 1-5 containing ZnO-P1 to ZnO-P5 provided in Examples 1-5 of the present invention are slightly better than those of foaming solutions 6-11 containing ZnO-P6 to ZnO-P11 provided in Examples 6-11 of the present invention, and also slightly better than the foaming abilities of the comparative foaming solutions containing only APGS and WP2101 but not flake zinc oxide particles.

[0125] Table 1 also shows that the foam separation half-life of foaming liquid 6-foaming liquid 11 containing ZnO-P6 to ZnO-P11 provided in Examples 6-11 of the present invention is less than 2300s, indicating that the stability of these foaming liquids is slightly worse, but still significantly better than the stability of the comparative foaming liquid. The separation half-life of foaming liquid 2-foaming liquid 5 containing ZnO-P2 to ZnO-P5 provided in Examples 2-5 of the present invention is between 2300s and 2500s, indicating that the stability of the foam system is better, and better than that of foaming liquid 6-foaming liquid 11. The foam separation half-life of foaming liquid 1 containing ZnO-P1 provided in Example 1 of the present invention is as high as 2582s, indicating that the stability of this foam system is the best. Compared with the separation half-life of the comparative foaming liquid, i.e., 0.4%APGS+0.1%WP2101, i.e., 1256s, the stability of the foam system is more than doubled.

[0126] In summary, this invention provides the first method for preparing zinc oxide particles with a regular hexagonal plate-like structure via hydrothermal synthesis using zinc salts, alkali, and urea. The preparation method is simple, quick, and easy to operate, with mild reaction conditions, short reaction time, low requirements for experimental equipment (i.e., simple experimental equipment), and high purity of the obtained product. The zinc oxide particles prepared in this invention exhibit a regular hexagonal plate-like structure, possessing characteristics such as high specific surface area, good foam stability, temperature and salt resistance, and good compatibility with formation water. It is suitable for foam flooding technology to enhance oil recovery in high-temperature, high-salinity oil reservoirs and has promising industrial application prospects.

[0127] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A method for preparing flaky zinc oxide particles, characterized in that, include: Step (1): Mix the zinc salt aqueous solution and the citric acid / sodium citrate mixed aqueous solution evenly, add the alkali solution, and then add the urea aqueous solution to obtain a mixed solution; Step (2): Allow the mixed solution to undergo a hydrothermal reaction; Step (3): Filter the suspension obtained after the reaction in step (2) to obtain the filter material, and then wash and dry the filter material in sequence to obtain flaky zinc oxide particles.

2. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of zinc salt, citric acid and sodium citrate to urea is 10-50:1:

50.

3. The preparation method according to claim 1 or 2, characterized in that, In step (1), the zinc salt includes any one or more of zinc acetate, zinc chloride, zinc sulfate, and zinc nitrate.

4. The preparation method according to claim 1, characterized in that, In step (1), an alkaline solution is added to adjust the pH of the system to 6.6-6.

9.

5. The preparation method according to claim 1 or 4, characterized in that, The alkaline solution includes any one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and ammonia solution.

6. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the hydrothermal reaction is 120-140℃ and the time is 160-200min.

7. A type of flaky zinc oxide granules, prepared by the method for preparing flaky zinc oxide granules according to any one of claims 1-6, wherein, The zinc oxide particles have a regular hexagonal sheet-like structure.

8. The flaky zinc oxide particles according to claim 7, characterized in that, The particle size of the flaky zinc oxide particles is 10-90 μm.

9. The use of the flaky zinc oxide particles as a foam stabilizer according to claim 7 or 8.

10. A foam system comprising a foam stabilizer and a foaming agent, characterized in that, The foam stabilizer is the flaky zinc oxide particles as described in claim 7 or 8.

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