Polymer-nano composite pour point depressant and preparation method thereof

Abstract

The present invention discloses a polymer-nano composite pour point depressant and a preparation method thereof, the method comprising the following steps: surface-modifying MXene with hexadecyltrimethoxysilane to obtain GMXene; and solution-blending GMXene with the polymer pour point depressant to obtain the polymer-nano composite pour point depressant. The present invention uses hexadecyltrimethoxysilane to surface-modify MXene, forming silicon-oxygen bonds on its surface, and improving the adsorption of crude oil and the dispersibility of the pour point depressant in crude oil through a bridging effect between the polymer and the crude oil interface. After the modified MXene is surface-modified on the ethylene-vinyl acetate copolymer pour point depressant, the layered structure of the MXene is used to form a biomimetic "brick-mud" structure, making the wax crystals precipitated in the crude oil large and dense, reducing space occupancy, effectively weakening the ability of the wax crystals to form a three-dimensional network gel structure, and improving the pour point depressant effect.

Description

Technical Field

[0001] The present invention relates to the technical field of pour point depressants, and in particular to a method for preparing a polymer-nano composite pour point depressant. Background Art

[0002] During crude oil pipeline transportation, as the oil temperature drops, wax crystals within the crude oil continuously precipitate and gradually aggregate to form a three-dimensional, gelled network structure. This reduces fluidity and reduces the effective pipeline diameter, potentially leading to safety incidents such as blockage and condensation. Therefore, in the oil industry, lowering the pour point of crude oil and improving its low-temperature fluidity are extremely important. Adding a pour point depressant (Pour Point Depressant) is recognized as one of the most effective methods for ensuring crude oil transportation safety, due to its low cost and high efficiency.

[0003] Currently commonly used pure polymer pour point depressants are inefficient. However, the nanomaterial MXene offers excellent mechanical strength, thermal conductivity, low weight, high surface area, and structural stability. It can be combined with polymers to enhance performance and subsequently modified and grafted to produce desired physical and chemical properties. Its unique multilayer structure and excellent physical and chemical properties make it an ideal candidate for constructing biomimetic "brick and mortar" structures. Therefore, the development of efficient pour point depressants for the low-temperature transportation of high-pour point crude oil has become an urgent task. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a polymer-nano composite pour point depressant and a preparation method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In one aspect, the present invention provides a method for preparing a polymer-nano composite pour point depressant, comprising the following steps:

[0007] (1) Surface modification of MXene with hexadecyltrimethoxysilane to obtain GMXene;

[0008] (2) The GMXene obtained in step (1) is solution-blended with a polymer pour point depressant to obtain the polymer-nano composite pour point depressant.

[0009] As a preferred embodiment, in step (1), the MXene is prepared by a liquid phase exfoliation method;

[0010] Preferably, the liquid phase exfoliation method comprises the following steps: stirring the MAX phase Ti3AlC2 powder in an etchant at 30-50°C and 1000-1500 rpm for 12-24 hours;

[0011] Preferably, the etchant is a hydrofluoric acid solution;

[0012] Preferably, the method further comprises post-processing of centrifugation, washing, filtration and drying.

[0013] As a preferred embodiment, in step (1), the surface modification comprises the following steps:

[0014] MXene and hexadecyltrimethoxysilane were reacted in a solution by stirring to complete the surface modification;

[0015] Preferably, the stirring reaction temperature is 60-70°C;

[0016] Preferably, the stirring reaction time is 3.5 to 4.5 hours;

[0017] Preferably, the mass ratio of the MXene to hexadecyltrimethoxysilane is 1:0.5-1;

[0018] Preferably, the solution is a methanol-water solution;

[0019] In certain specific embodiments, post-processing including centrifugation, filtration, drying and grinding is also included.

[0020] As a preferred embodiment, in step (2), the temperature of the solution blending is 60-80°C;

[0021] Preferably, the solution blending time is 3 to 5 hours;

[0022] Preferably, the reaction solvent of the solution blend is xylene;

[0023] Preferably, the solution blending is carried out in an inert atmosphere;

[0024] Preferably, the method further comprises the steps of precipitating the product of the solution blending method with a poor solvent, and obtaining the polymer-nano composite pour point depressant by suction filtration and drying;

[0025] Preferably, the poor solvent is methanol;

[0026] Preferably, the drying is performed at 30-50° C. for 12-24 hours.

[0027] As a preferred embodiment, in step (2), the polymer pour point depressant is an ethylene-vinyl acetate copolymer pour point depressant;

[0028] Preferably, the mass ratio of the ethylene-vinyl acetate copolymer pour point depressant to the Mxene is 5:1-5.

[0029] In another aspect, the present invention provides a polymer-nano composite pour point depressant obtained by the above preparation method.

[0030] In another aspect, the present invention provides use of the polymer-nano composite pour point depressant in preparing a crude oil pour point depressant.

[0031] Preferably, the content of the polymer-nano composite pour point depressant in crude oil is 400 to 1200 ppm, preferably 400 to 800 ppm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention uses hexadecyltrimethoxysilane to modify the surface of MXene, forming silicon-oxygen bonds on the surface of the two-dimensional material MXene, which can form a bridging effect at the interface between the polymer and crude oil, thereby improving the adsorption of crude oil and the dispersibility of the pour point depressant in crude oil.

[0034] (2) The present invention blends MXene surface-modified with hexadecyltrimethoxysilane with ethylene-vinyl acetate copolymer pour point depressant in a solution, performs surface modification on the pour point depressant, and utilizes the layered structure of MXene to form a bionic "brick-mud" structure, so that the wax crystals precipitated from the crude oil are large and dense, reducing the space occupied, effectively weakening the ability of the wax crystals to form a three-dimensional network gel structure, releasing the bound liquid oil, and improving the pour point depressant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart for preparing the polymer-nano composite pour point depressant in Example 1 of the present invention.

[0036] Figure 2 FTIR spectra of MXene, GMXene, EVA and EVA-GMX (5:2) in Example 1 of the present invention.

[0037] Figure 3 This is a graph showing the water contact angle test results of MXene and GMXene in Example 1 of the present invention.

[0038] Figure 4 This is a graph showing the pour point test results of crude oils with added EVA, EVA-GMX (5:1), and EVA-GMX (5:2) in Example 1 of the present invention.

[0039] Figure 5a Viscosity-temperature curves of crude oil with different concentrations of EVA-GMX (5:1) added; Figure 5b Viscosity-temperature curves of crude oil with different concentrations of EVA-GMX (5:2) added; Figure 5c Viscosity-temperature curves of crude oil without / doped with 800 ppm EVA / GMXene. DETAILED DESCRIPTION

[0040] The following embodiments are merely some of the embodiments of the present invention, rather than all of them. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0041] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0042] Example 1

[0043] This embodiment provides a polymer-nano composite pour point depressant, and its preparation method is as follows Figure 1 As shown, the following steps are included:

[0044] (1) Preparation of Ti3AlC2

[0045] Step 1: Add 20 mL of 40% hydrofluoric acid solution to a polytetrafluoroethylene (100 mL) reactor;

[0046] Step 2: Weigh 1g of MAX phase Ti3AlC2 and slowly add it into the reactor in small amounts. Place it in an oil bath and stir it with magnetic stirring at 1000rpm and 40℃ for 24h.

[0047] Step 3: Pour the resulting solution into a centrifuge tube, centrifuge at 5000 rpm for 5 minutes, add deionized water, and centrifuge and wash 5 to 6 times until the pH of the filtrate is neutral;

[0048] Step 4: Filter with a 0.22 μm water filter membrane, place the filtered product in a vacuum drying oven at 40°C for 2 hours, grind into powder, and obtain MXene phase Ti3AlC2;

[0049] (2) Surface modification of Ti3AlC2

[0050] Step 1: Prepare 100 mL of methanol-water solution (volume ratio 9:1);

[0051] Step 2: 1 g of MXene phase Ti3AlC2 was added to a methanol-water solution and ultrasonically dispersed for 30 min with mechanical stirring to form a uniform and stable dispersion.

[0052] Step 3: Add 1 mL of hexadecyltrimethoxysilane to the dispersion, place it in an oil bath, and stir magnetically at 1000 rpm and 70°C for 3.5 h to promote chemical bonding between the silane groups and the MXene surface.

[0053] Step 4: Centrifuge at 5000 rpm for 5 minutes, add deionized water, and centrifuge and wash 5 to 6 times; filter with filter paper, place in a vacuum drying oven at 40°C for 2 hours, and grind into powder to obtain the modified product GMXene (abbreviated as GMX);

[0054] (III) Preparation of polymer-nano composite pour point depressant

[0055] Step 1: Add 40 mL of xylene into a flask, weigh 0.4 g, 0.8 g, and 2 g of GMXene into the flask, and ultrasonicate for 30 minutes to form a dispersion.

[0056] Step 2: Add 40 mL of xylene to a three-necked flask, weigh 2 g of ethylene-vinyl acetate copolymer pour point depressant (EVA, VA content is 25 wt.%) and add it to the flask. Stir at 500 rpm and 70°C until it is completely dissolved in xylene.

[0057] Step 3: Under nitrogen atmosphere, slowly add the dispersion liquid in step 1 to the solution in step 2, and react at 500 rpm and 70°C for 4 hours;

[0058] Step 4: The mixed solution was precipitated with excess methanol, and the precipitate was filtered through filter paper and dried at 40 ° C for 12 h to obtain the final product EVA-GMX, which were EVA-GMX (5:1), EVA-GMX (5:2) and EVA-GMX (1:1).

[0059] Performance Testing

[0060] (1) The Fourier transform infrared spectra of MXene, GMXene, EVA and EVA-GMX (5:2) in Example 1 are shown in Figure 2. Figure 2 , as can be seen from the figure:

[0061] EVA-GMX formed by solution blending of EVA and GMXene has a new characteristic peak of 1136 cm-1 compared to pure EVA. -1 and 530cm -1 , which correspond to the Si-O-Si asymmetric stretching vibration of GMXene and the characteristic peak Ti-O stretching vibration of MXene, respectively, which indicates the presence of GMXene in the composite material and also shows that the Ti-O structure remains stable after blending treatment.

[0062] (2) The water contact angle test results of MXene and GMXene in Example 1 are shown in Figure 3 , where a1-a3 are MXene and b1-b6 are GMXene. It can be seen from the figure that:

[0063] Unmodified MXene rapidly absorbs water and expands within 3 seconds after contact with water, demonstrating its hydrophilicity (a1-a3). GMXene exhibits superhydrophobicity, preventing water droplets from adhering to its surface (b1-b5). The measured water contact angle on the GMXene surface is 153.58° (b6), indicating that the EVA-MXene nanocomposite pour point depressant can be uniformly dispersed in crude oil, significantly reducing its viscosity and improving its flow properties.

[0064] (3) De-condensation effect test

[0065] Test Example 1: This test is aimed at high pour point thick oil containing wax and colloid asphaltene in a block of Shengli Oilfield. The pour point depressants prepared in Example 1 are used to compare and evaluate the pour point depressing effect (condensation point). The evaluation standard is implemented with reference to GB / T 26985-2018.

[0066] Test conditions: Pour point depressant dosage is 800mg / L, evaluation results are as follows Figure 4 As shown;

[0067] Depend on Figure 4 It can be seen that the three pour point depressants provided in Example 1 have obvious pour point depressing effects on high pour point crude oil in a block of Shengli Oilfield, and a high pour point depressing effect can be achieved at a relatively low dosage.

[0068] Test Example 2: This test is aimed at high-viscosity viscous oil containing wax and colloid asphalt in a block of Shengli Oilfield, and the pour point depressants prepared in Example 1 are used to conduct comparative evaluation of rheological properties (viscosity-temperature curve).

[0069] Test conditions: Crude oil samples without and with pour point depressant were preheated at 60°C for 30 min and cooled at a fixed rate of 0.5°C / min. The evaluation results are shown in the attached figure. Figures 5a-5c As shown:

[0070] When the three pour point depressants provided in Example 1 were added at 800 ppm, the viscosity of the crude oil at 10°C dropped to 12.4 Pa·s and 11.4 Pa·s, respectively. Compared to crude oil without the addition of pour point depressants, the viscosity decreased by 47.2% and 51.5%, respectively. When the addition level was increased to 1200 ppm, the crude oil viscosity increased abnormally. This is because the excess pour point depressant did not bind to the wax crystals and remained suspended in the crude oil, triggering a self-gelling effect and increasing viscosity. The experimental results show that the EVA-GMX composite material can significantly improve the low-temperature fluidity and rheological properties of crude oil.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a polymer-nano composite pour point depressant, characterized in that: The following steps are involved: (1) Surface modification of MXene with hexadecyltrimethoxysilane to obtain GMXene; (2) The GMXene obtained in step (1) is solution-blended with a polymer pour point depressant to obtain the polymer-nano composite pour point depressant; the method further comprises the steps of precipitating the product of the solution blending method in step (2) with a poor solvent, and obtaining the polymer-nano composite pour point depressant by suction filtration and drying; the polymer pour point depressant is an ethylene-vinyl acetate copolymer pour point depressant; and the mass ratio of the ethylene-vinyl acetate copolymer pour point depressant to the MXene is 5:1~5.

2. The preparation method according to claim 1, characterized in that In step (1), the MXene is prepared by a liquid phase exfoliation method.

3. The preparation method according to claim 2, wherein The liquid phase stripping method includes the following steps: stirring MAX phase Ti3AlC2 powder in an etchant at 30-50°C and 1000-1500 rpm for 12-24 hours.

4. The preparation method according to claim 3, characterized in that The etchant is a hydrofluoric acid solution.

5. The preparation method according to claim 3, characterized in that The liquid phase stripping method further includes post-processing of centrifugation, washing, filtration and drying.

6. The preparation method according to claim 1, characterized in that In step (1), the surface modification comprises the following steps: The surface modification was completed by stirring MXene and hexadecyltrimethoxysilane in solution.

7. The preparation method according to claim 6, characterized in that The temperature of the stirring reaction is 60-70°C.

8. The preparation method according to claim 6, wherein The stirring reaction time is 3.5 to 4.5 h.

9. The preparation method according to claim 6, characterized in that The mass ratio of the MXene to hexadecyltrimethoxysilane is 1:0.5~1.

10. The preparation method according to claim 6, characterized in that The solution is a methanol-water solution.

11. The preparation method according to claim 1, characterized in that In step (2), the temperature of the solution blending is 60-80°C.

12. The preparation method according to claim 1, wherein In step (2), the solution is blended for 3 to 5 hours.

13. The preparation method according to claim 1, characterized in that In step (2), the reaction solvent for the solution blending is xylene.

14. The preparation method according to claim 1, characterized in that In step (2), the solution blending is carried out in an inert atmosphere.

15. The preparation method according to claim 1, characterized in that The poor solvent is methanol.

16. The preparation method according to claim 1, wherein The drying step is drying at 30-50° C. for 12-24 hours.

17. The polymer-nano composite pour point depressant obtained by the preparation method according to any one of claims 1 to 16.

18. Use of the polymer-nano composite pour point depressant according to claim 17 in the preparation of a crude oil pour point depressant.

19. The use according to claim 18, characterized in that The content of the polymer-nano composite pour point depressant in crude oil is 400-1200 ppm.

20. The use according to claim 19, characterized in that The content of the polymer-nano composite pour point depressant in crude oil is 400-800 ppm.

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