High-enthalpy-value phase change wax based on olefin hydrogenation sweating separation and preparation method of high-enthalpy-value phase change wax

Abstract

The invention relates to the technical field of phase change materials, in particular to high-enthalpy-value phase change wax based on olefin hydrogenation sweating separation. The olefin raw materials comprise 10 olefin, 12 olefin, 14 olefin, 16 olefin, 18 olefin, 20 olefin, 22 olefin, 24 olefin, 26 olefin, 28 olefin, 30 olefin, C20-C24 mixed olefin, 26-28 mixed olefin and expanded graphite. Each olefin is subjected to hydrogenation reaction to prepare 10 alkane, 12 alkane, 14 alkane, 18 alkane, 20 alkane, 22 alkane, 24 alkane, 26 alkane, 28 alkane, 30 alkane, C20-C24 mixed alkane and 26-28 mixed alkane, and expanded graphite is added. A product obtained by hydrogenation of C20-C24 and 26-28 alkanes is subjected to sweating separation to obtain the phase change wax rich in 20 alkanes, 22 alkanes, 24 alkanes, 26 alkanes and 28 alkanes. All alkanes are added into the expanded graphite to prepare the high-thermal-conductivity phase change wax with melting points of-29 DEG C,-9 DEG C, 5 DEG C, 18 DEG C, 28 DEG C, 36 DEG C, 43 DEG C, 50 DEG C, 56 DEG C, 61 DEG C and 65 DEG C, and the thermal conductivity coefficient is increased to 1.5-15 W.m.K. The heat-conducting property is improved, and the industrial production feasibility is achieved.

Description

Technical Field

[0001] This invention relates to the field of phase change functional materials, specifically to a high enthalpy, high thermal conductivity phase change wax based on olefin hydrogenation and sweating separation and its preparation method. Background Technology

[0002] Phase change materials (PCMs) are functional materials that can absorb, store, and release heat energy through a phase change process within a specific temperature range. They are widely used in textiles, building energy conservation, electronic thermal management, new energy storage, cold chain logistics, and aerospace. Among them, PCM waxes have become an important direction in PCM research and application due to their high phase change enthalpy, excellent chemical stability, low cost, absence of supercooling, and environmental friendliness.

[0003] Different application fields have significantly different requirements for the phase change temperature of phase change waxes: thermal protection of electronic devices typically requires a phase change temperature of 25℃ to 90℃; building energy conservation and indoor heating fields mostly use phase change waxes with a phase change temperature of 15℃ to 28℃ to achieve temperature buffering and waste heat storage; while industrial waste heat recovery and power battery thermal management fields prefer a phase change temperature range of 30℃ to 70℃. Therefore, achieving high enthalpy, high thermal conductivity, and precise control of the phase change temperature of phase change waxes has become a key goal in their research and development and production.

[0004] Currently, phase change waxes are mostly obtained through the rectification and purification of petroleum fractions or Fischer-Tropsch waxes. Related patents, such as CN110628391A, use vacuum distillation to separate continuous fractions; CN105505331A and CN14560739 use molecular distillation combined with stabilizer addition; CN111996036A combines multi-stage cryogenic separation with continuous rectification; CN202310287510.0 prepares composite phase change waxes by mixing different grades of paraffin wax and adding thermal conductive agents and flame retardants; CN112322350A utilizes a combination of rectification and sweating to increase enthalpy. While these methods can improve product performance, they generally suffer from complex processes, high energy consumption, poor component uniformity, and difficulty in industrialization.

[0005] In contrast, this invention uses monomeric or mixed olefins as raw materials, hydrogenating them to obtain high-purity alkane phase change wax. It achieves the targeted collection of alkanes with different carbon numbers through stepwise heating and sweating, controlling the homogeneity of components and the "on-demand customization" of the phase change temperature from the source. This eliminates the need for distillation pretreatment, significantly simplifying the process and improving separation efficiency. Simultaneously, the introduction of expanded graphite significantly improves the thermal conductivity of the phase change wax, solving the problems of low thermal conductivity (only 0.15~0.22 W·m⁻¹·K⁻¹) and slow heat transfer in traditional phase change waxes.

[0006] In summary, existing technologies still have shortcomings in terms of controllability of phase change temperature, improvement of enthalpy and thermal conductivity, making it difficult to simultaneously achieve high purity, high enthalpy, and rapid thermal conductivity. Furthermore, they suffer from high production costs and limited industrialization. Therefore, developing a simple, cost-effective method for preparing high-enthalpy phase change waxes that enables precise temperature control and enhanced thermal conductivity has become a pressing technical problem to be solved in this field. Summary of the Invention

[0007] To overcome the problems of low precision in phase change temperature control, complex composition, poor thermal conductivity, and complex processes in existing phase change waxes, this invention aims to provide a method for preparing high-enthalpy phase change wax based on olefin hydrogenation and sweating separation. This invention introduces an expanded graphite thermal conductivity enhancement system into the obtained phase change wax, significantly improving its thermal conductivity efficiency and effectively solving the bottleneck problems of low thermal conductivity and slow heat storage and release rates in organic phase change materials. The method of this invention features a simple process flow, low energy consumption, and industrial scalability. The resulting phase change wax has advantages such as uniform composition, high enthalpy, excellent thermal conductivity, and strong controllability of phase change temperature, making it suitable for various applications such as cold chain logistics, textiles, building energy conservation, thermal management of electronic devices, and thermal control of power batteries. The phase change wax of this invention has high purity, high enthalpy, and significantly improved thermal conductivity, and the process is simple and cost-controllable, making it suitable for large-scale production.

[0008] The objective of this invention can be achieved through the following technical solutions: A method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation, characterized by comprising the following steps: (1) Select olefin raw materials, wherein the olefin raw materials include 10 olefins, 12 olefins, 14 olefins, 16 olefins, 18 olefins, 20 olefins, 22 olefins, 24 olefins, 26 olefins, 28 olefins, 30 olefins, C20 to C24 mixed olefins and 26 to 28 mixed olefins; (2) The olefin raw materials are subjected to hydrogenation reactions to obtain the corresponding 10-alkane, 12-alkane, 14-alkane, 16-alkane, 18-alkane, 20-alkane, 22-alkane, 24-alkane, 26-alkane, 28-alkane, 30-alkane, C20-C24 mixed alkanes and 26-28 mixed saturated alkanes; (3) The hydrogenation products of C20-C24 mixed olefins and 26-28 mixed olefins are separated by sweating to obtain a phase change wax rich in 20-alkane, 22-alkane, 24-alkane, 26-alkane and 28-alkane; (4) Add expanded graphite to the phase change wax and disperse it evenly to obtain a thermally conductive phase change wax based on olefin hydrogenation sweating separation.

[0009] Optionally, the hydrogenation reaction temperature in step (2) is 120-160°C, the hydrogenation pressure is 3-6 MPa, and the reaction time is 1-15 hours.

[0010] Optionally, the temperature for sweating separation in step (3) is 32-70℃, and the sweating separation time is 15-30 hours.

[0011] Optionally, in step (4), the amount of expanded graphite added is 8-15% of the mass of the phase change wax, the dispersion temperature is 60-90℃, and the dispersion time is 10-50 minutes.

[0012] Optionally, the melting point range of the phase change wax is −29℃ to 65℃.

[0013] Optionally, phase change waxes can be prepared to produce products with melting points of −29℃, −9℃, 5℃, 18℃, 28℃, 36℃, 43℃, 50℃, 56℃, 61℃ and 65℃ respectively.

[0014] Optionally, the thermal conductivity of the phase change wax is 1.5 to 15 W·m⁻¹·K⁻¹.

[0015] Optionally, the high enthalpy phase change wax is composed of 10-alkane, 12-alkane, 14-alkane, 16-alkane, 18-alkane, 20-alkane, 22-alkane, 24-alkane, 26-alkane, 28-alkane, 30-alkane, 20-alkane, 22-alkane, 24-alkane, 26-alkane, 28-alkane, and 30-alkane combined with expanded graphite. The expanded graphite is uniformly dispersed in the phase change wax, and the thermal conductivity is significantly improved.

[0016] Optionally, the thermal conductivity of the high enthalpy phase change wax is increased to 1.5–15 W·m⁻¹·K⁻¹.

[0017] The beneficial effects of this invention are: This invention, for the first time, uses the hydrogenation products of monomeric or mixed olefins as raw materials for sweating separation, overturning the traditional "distillation followed by sweating" process. It achieves component homogenization and precise control of phase change temperature from the source, significantly improving the purity and enthalpy of the phase change wax. Through stepwise heating and sweating separation technology, alkanes with specific carbon numbers can be obtained directionally, thus achieving "on-demand customization" of the phase change temperature to meet the personalized needs of different energy storage temperature zones. This invention introduces an expanded graphite thermally conductive network structure into the phase change wax, forming highly efficient thermal conduction channels and increasing the material's thermal conductivity to 1.5–15 W·m⁻¹·K⁻¹, solving the technical bottlenecks of low thermal conductivity and slow heat storage / release rates in traditional organic phase change waxes. These innovative designs achieve a synergistic unity of high purity, high enthalpy, and high thermal conductivity, providing a new technical path for the industrial preparation of high-performance phase change energy storage materials. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 This is a diagram showing the enthalpy values ​​of normal-form 16-alkanes. Figure 2This is a enthalpy diagram of ortho-22-alkane; Figure 3 This is a diagram showing the enthalpy values ​​of ortho-18-alkanes. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0021] Example 1 The purpose of this embodiment is to prepare a high enthalpy phase change wax with a phase change temperature of approximately 18°C.

[0022] S1, 30 parts of C16 olefin and 1.8 parts of Raney nickel catalyst were added to a high-pressure reactor. After purging the air with nitrogen, hydrogen was introduced to pressurize to 11 atm, and the mixture was heated to 185°C for 5 hours. After cooling, the catalyst was removed by filtration to obtain 16-n-alkane with an enthalpy of 247.96 kJ / kg. The enthalpy diagram is as follows. Figure 1 As shown.

[0023] S2, mechanically stir the expanded graphite at 75°C for 1 hour to ensure uniform dispersion and mixing; S3. Pour the mixture into a mold, allow it to cool naturally to room temperature, and then press the mixture into a phase change sheet using a press. The phase change temperature was tested to be 18℃, and the thermal conductivity was 2.2 W·m⁻¹·K⁻¹.

[0024] Example 2 The purpose of this embodiment is to prepare a high enthalpy phase change wax with a phase change temperature of approximately 43°C.

[0025] S1, 30 parts of C22 olefin and 2.2 parts of Raney nickel catalyst were weighed and placed in an autoclave. After replacing the air with nitrogen, hydrogen was introduced and the pressure was increased to 13 atm. The mixture was heated to 200℃ and reacted for 7 hours. After cooling, the mixture was filtered to obtain 22-carbon saturated alkanes; the enthalpy value was 227.91 kJ / kg. The enthalpy value diagram corresponds to... Figure 2 .

[0026] S2, add 9 parts of expanded graphite, stir at 85°C for 1.5 hours to disperse it evenly; S3. The mixture was slowly cooled and solidified to obtain a blackish-gray solid phase change wax. Test results showed that the phase change temperature was 40℃ and the thermal conductivity was 2.8 W·m⁻¹·K⁻¹.

[0027] Example 3 The purpose of this embodiment is to prepare a high enthalpy phase change wax with a phase change temperature of approximately 28°C.

[0028] S1, 200 g of 18-olefin and 10 g of Raney nickel catalyst were weighed and placed in a 500 mL autoclave. After replacing the air with nitrogen, hydrogen was added to 12 atm, and the reaction was carried out at 190 °C for 6 hours. After cooling, the catalyst was removed by filtration to obtain 18-saturated alkanes. The phase transition temperature of the 18-alkane was measured to be 28 °C, and the phase transition enthalpy was 237.37 KJ / kg.

[0029] S3, 25% expanded graphite powder is added to the 18-alkane in S1, and stirred at 80°C for 1 hour to form a stable dispersion; then it is pressed into a phase change sheet in a press with a thermal conductivity of 6.5 W·m⁻¹·K; Example 4 S1, 200 g of C26-C28 olefins and 15 g of Raney nickel catalyst were weighed and placed in a 500 mL autoclave, charged with hydrogen to 12 atm, and reacted at 190 °C for 6 hours. After cooling, the catalyst was removed by filtration to obtain a mixed saturated alkanes of C26-C28.

[0030] S2, S1 hydrogenation of C26-C28 mixed saturated alkanes is placed in a sweating dish to separate the alkanes rich in 26-alkane and the alkanes rich in 28-alkane; S3, 20% expanded graphite powder is added to the hydrogenated C26-C28 mixed saturated alkanes of S1, and stirred at 80°C for 1 hour to form a stable dispersion, which is then pressed into a phase change sheet in a press with a thermal conductivity of 4.8 W·m⁻¹·K⁻¹; S4, the two components of S2, rich in 26-alkane and rich in 28-alkane, were slowly cooled to room temperature and solidified to obtain phase change wax. The phase change temperatures were measured to be 56℃ and 61℃, respectively. The phase change temperatures were 228 KJ / kg and 226 KJ / kg, respectively.

[0031] In summary, this invention successfully prepared a multi-temperature-range phase change wax with high enthalpy, high thermal conductivity, and high stability through a three-step process of olefin hydrogenation, sweating separation, and expanded graphite composite, demonstrating strong technological innovation and promising prospects for industrial application.

Claims

1. A method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation, characterized in that, Includes the following steps: (1) Select olefin raw materials, wherein the olefin raw materials include 10 olefins, 12 olefins, 14 olefins, 16 olefins, 18 olefins, 20 olefins, 22 olefins, 24 olefins, 26 olefins, 28 olefins, 30 olefins, C20 to C24 mixed olefins and 26 to 28 mixed olefins; (2) The olefin raw materials are subjected to hydrogenation reactions to obtain the corresponding 10-alkane, 12-alkane, 14-alkane, 16-alkane, 18-alkane, 20-alkane, 22-alkane, 24-alkane, 26-alkane, 28-alkane, 30-alkane, C20-C24 mixed alkanes and 26-28 mixed saturated alkanes; (3) The hydrogenation products of C20-C24 mixed olefins and 26-28 mixed olefins were separated by sweating to obtain phase change wax rich in 20-alkane, 22-alkane, 24-alkane, 26-alkane and 28-alkane; (4) Add expanded graphite to the phase change wax and disperse it evenly to obtain a high thermal conductivity phase change wax based on olefin hydrogenation sweating separation.

2. The method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation according to claim 1, characterized in that, The hydrogenation reaction temperature in step (2) is 120-160℃, the hydrogenation pressure is 3-6MPa, and the reaction time is 1-15 hours.

3. A method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation according to claim 1 or 2, characterized in that, The sweating separation temperature in step (3) is 32-70℃, and the sweating separation time is 15-30 hours.

4. A method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation according to any one of claims 1 to 3, characterized in that, In step (4), the amount of expanded graphite added is 8-15% of the mass of the phase change wax, the dispersion temperature is 60-90℃, and the dispersion time is 10-50 minutes.

5. A method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation according to any one of claims 1 to 4, characterized in that, The melting point range of the phase change wax is −29℃ to 65℃.

6. A method for preparing a high-enthalpy phase change wax based on olefin hydrogenation and sweating separation according to any one of claims 1 to 5, characterized in that, The phase change wax can be prepared into products with melting points of −29℃, −9℃, 5℃, 18℃, 28℃, 36℃, 43℃, 50℃, 56℃, 61℃ and 65℃ respectively.

7. A method for preparing a high-enthalpy, high-thermal-conductivity phase change wax based on olefin hydrogenation and sweating separation according to any one of claims 1 to 6, characterized in that, The thermal conductivity of the phase change wax is 1.5–15 W·m⁻¹·K⁻¹.

8. A high-enthalpy phase change wax prepared by any one of claims 1 to 7, characterized in that, The high enthalpy phase change wax is composed of 10-alkane, 12-alkane, 14-alkane, 16-alkane, 18-alkane, 20-alkane, 22-alkane, 24-alkane, 26-alkane, 28-alkane, 30-alkane, 20-alkane, 22-alkane, 24-alkane, 26-alkane, 28-alkane, and 30-alkane combined with expanded graphite.

9. The high enthalpy, high thermal conductivity phase change wax according to claim 8, characterized in that, The thermal conductivity of the high enthalpy phase change wax is increased to 1.5–15 W·m⁻¹·K⁻¹.

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