Preparation method and application of phenol oil-based phase separation phenolic aerogel

Abstract

The application discloses a preparation method and application of a phenol oil-based phase separation phenolic aerogel, and belongs to the field of high-value utilization of coal tar. The preparation method of the phase separation phenolic aerogel comprises the following steps: taking melamine foam as a skeleton, phenol oil, phenols and aldehydes as raw materials, mixing different polar organic matters as solvents, and taking acid as a catalyst to perform a solvothermal reaction to obtain a phase separation phenolic organic gel; and vacuum drying is performed to obtain the phase separation phenolic aerogel. The phase separation phenolic aerogel with adjustable porosity and connectivity can be obtained by adjusting the polarity and ratio of the mixed solvents, and the aerogel can be used for solar-driven interfacial water evaporation. In the application, phenol oil is used to replace phenols to prepare the phenolic aerogel with high connectivity, the raw material cost is reduced, the utilization value of the phenol oil is improved, the operation is simple, complex freeze drying and template adjustment pores are not needed, and the application prospect of the phenol oil in solar-driven interfacial water evaporation is good.

Description

Technical Field

[0001] This invention belongs to the field of high-value utilization of coal tar, specifically relating to a method for preparing and applying phenolic aerogel with phenolic oil-based phase separation. Background Technology

[0002] Phenolic oil is a complex mixture, mainly derived from byproducts of coal pyrolysis / coking processes, and is rich in phenolic compounds and other harmful aromatic substances. Currently, the main method is the separation and purification of phenolic compounds, but this process is complex and generates large amounts of wastewater. Therefore, there is an urgent need to develop technologies for the high-value and low-carbon utilization of phenolic oil. This would not only reduce environmental pollution but also reduce resource waste and improve economic efficiency.

[0003] Although approximately 70% of the Earth's surface is covered by water, only about 3% of it is freshwater, and a large portion of this freshwater (about 87%) is frozen in glaciers and ice caps, making it difficult to utilize. Therefore, the amount of freshwater resources directly usable by humans on Earth is very limited, and the global water shortage will be further exacerbated by population and economic activity. To address this global challenge, seawater desalination is one of the most effective methods. Currently, seawater desalination technologies mainly include multi-stage flash evaporation and reverse osmosis, but these methods suffer from high energy consumption, large investment, and difficulty in scaling up. Therefore, solar-driven interfacial water evaporation technology, with its advantages of high energy efficiency and zero carbon emissions, has attracted widespread attention. Among these technologies, aerogels, due to their high porosity, low thermal conductivity, and low density, are widely used in solar-driven interfacial water evaporation.

[0004] The preparation of phenolic aerogels requires a large amount of phenol, resulting in high costs. Therefore, finding alternatives to phenol is of great significance. Given that phenolic oil is rich in various phenolic compounds, it holds promise as a substitute for phenol in the preparation of phenolic aerogels. Moreover, phenolic oil substitution can enhance photothermal properties without the need for additional expensive light absorbers, further reducing costs. Furthermore, the connectivity of pores significantly affects the water evaporation performance of aerogels; therefore, developing highly interconnected phenolic oil-based phase-separated phenolic aerogels is of great importance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying phenolic oil-based phase-separated phenolic aerogel. By using inexpensive phenolic oil to replace part of the petrochemical raw material phenol, a phase-separated phenolic aerogel with high photothermal conversion performance and rapid water escape is synthesized. This provides a new approach for the high-value utilization of phenolic oil and the modulation of aerogel pore size. At the same time, this aerogel can be applied to solar-driven interfacial water evaporation with good results.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing phenolic aerogel with phenolic oil-based phase separation includes the following steps:

[0008] 1) Add phenols and phenolic oils to a mixed solvent and stir until dissolved to obtain a mixed solution;

[0009] 2) Place the melamine foam into the above solution, then add aldehydes and acids to obtain a mixed sol;

[0010] 3) The above mixed sol was subjected to a solvothermal reaction to obtain a phase-separated phenolic oil-based phenolic organic gel;

[0011] 4) Wash the above phenolic organic gel with ethanol and then dry it under vacuum to obtain phase-separated phenolic oil-based phenolic organic aerogel.

[0012] Furthermore, in step (1), the mixed solvent is selected from methanol, ethanol, isopropanol, n-butanol, isobutanol, and acetone, and two of them are mixed in a volume ratio of 0:1–1:0; the phenol is one of phenol, o-cresol, m-cresol, p-cresol, p-ethylphenol, and resorcinol; the mass ratio of phenolic oil to phenol is 1:9–1:1.

[0013] Furthermore, in step (2), the aldehydes are one or two of formaldehyde, paraformaldehyde, and furfural; the acids are one of hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, and oxalic acid.

[0014] Furthermore, in steps (1) and (2), the ratio of phenols, mixed solvents, aldehydes and acids is 0.8–1.44 g: 10–50 mL: 1.5–8.5 mL: 0.5–2.5 mL.

[0015] Furthermore, in step (3), the solvothermal reaction temperature is 80–160℃ and the time is 6–36h.

[0016] It should be further explained that, based on the solvent polarity and the difference in solubility of phenolic resin in different solvents, by adjusting the type and ratio of solvents, it is possible to obtain phenolic oil-based phase-separated phenolic aerogels with interconnected pores, thereby achieving high porosity and high connectivity.

[0017] Another object of the present invention is to provide the application of the phenolic oil-based phase-separated phenolic aerogel obtained by the above preparation method in solar-driven interfacial water evaporation.

[0018] The beneficial effects of this invention are:

[0019] 1. The method for preparing highly interconnected phenolic oil-based phase separation phenolic aerogels of the present invention is simple and does not require complex freeze drying and templates.

[0020] 2. This invention prepares phase-separated phenolic aerogels by replacing part of the phenol with phenol oil to enhance photothermal properties, without the need for additional light absorbers.

[0021] 3. This invention uses melamine foam as a framework and a mixture of two organic compounds of different polarities as a solvent to prepare phenolic oil-based phase-separated phenolic aerogels, thereby enhancing the mechanical properties of phenolic aerogels.

[0022] 4. Phenolic oil is mainly used as a raw material for phenol extraction in industrial production. The process is complex, the purification is difficult, and it pollutes the environment. This invention uses phenolic oil to replace part of the phenols to prepare phenolic aerogel, which not only improves the utilization value of phenolic oil, but also replaces photothermal materials, reduces the cost of raw materials, and improves the solar-driven water evaporation performance of conventional phenolic aerogels. Therefore, it has good application prospects. Attached Figure Description

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Figure 1 This is a photograph of the aerogel used in Example 1 of the present invention.

[0025] Figure 2 The following are optical microscope images of aerogels in Examples 1-5 of this invention: (a) CPA-et, (b) CPA-buty, (c) CPA-isop, (d) CPA-et+buty and (e) CPA-et+isop.

[0026] Figure 3 These are the stress-strain curves of the aerogel in Examples 2-4 of this invention.

[0027] Figure 4 The saturated water content and water transport rate of the aerogels in Examples 1-5 of this invention are given.

[0028] Figure 5 The solar-driven water evaporation performance of the aerogels in Examples 1-5 of this invention. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] Weigh 1.12 g of phenol and 0.48 g of phenolic oil (phenol substitution rate 30%), add them to 30 mL of organic solvent (ethanol / n-butanol = 1:1), and stir until dissolved to obtain a mixed solution; place melamine foam (diameter 3.5 cm, height 4 cm) into the above solution, then add 5 mL of formaldehyde (35 wt%) and 1.5 mL of hydrochloric acid (37 wt%) to obtain a mixed sol; subject the above mixed sol to a solvothermal reaction at 120 °C for 12 h to obtain a phenolic oil-based phase-separated phenolic organic gel; wash the above phenolic organic gel with ethanol until the washing liquid is colorless, then vacuum dry to obtain a phenolic oil-based phase-separated phenolic organic aerogel (CPA-et+buty, Figure 1 The density is 0.061 g / cm³. 3 The phenolic resin balls are unevenly distributed. Figure 2 At 90% strain, the compressive strength is 1.63 MPa. Figure 3 The saturated water content is 13 g·g. -1 The water transport rate is 0.082 g·min. -1 ( Figure 4 Under one times the sunlight intensity, the water evaporation rate is 2.09 kg·m³. -2 h -1 ( Figure 5 It is 4.5 times that of pure water.

[0032] Example 2

[0033] Weigh 0.8 g of m-cresol and 0.8 g of phenolic oil (m-cresol substitution rate 50%), add them to 30 mL of ethanol, and stir until dissolved to obtain a mixed solution. Place melamine foam (diameter 3.5 cm, height 4 cm) into the above solution, then add 5 mL of formaldehyde (35 wt%) and 1.5 mL of hydrochloric acid (37 wt%) to obtain a mixed sol. Incubate the mixed sol at 140 °C for 12 h using a solvothermal reaction to obtain a phenolic oil-based phenolic organic gel. Wash the phenolic organic gel with ethanol until the washing solution is colorless, then vacuum dry to obtain a phenolic oil-based phenolic organic aerogel (CPA-et). The density is 0.060 g / cm³. 3 The number of phenolic resin balls is small and they are evenly distributed. Figure 2 At 90% strain, the compressive strength is 0.57 MPa. Figure 3 The saturated water content is 12 g·g. -1 The water transport rate is 0.066 g·min. -1 ( Figure 4 Under one times the sunlight intensity, the water evaporation rate is 1.81 kg·m³. -2 h -1 ( Figure 5 It is 3.9 times that of pure water, but significantly lower than that of phenolic oil-based phase-separated phenolic aerogel.

[0034] Example 3

[0035] Weigh 1.12 g of phenol and 0.48 g of phenolic oil (phenol substitution rate 30%), add them to 30 mL of n-butanol, and stir until dissolved to obtain a mixed solution. Place melamine foam (diameter 3.5 cm, height 4 cm) into the above solution, then add 5 mL of formaldehyde (35 wt%) and 1.5 mL of hydrochloric acid (37 wt%) to obtain a mixed sol. Incubate the mixed sol at 120 °C for 12 h using a solvothermal reaction to obtain a phenolic oil-based phenolic organic gel. Wash the phenolic organic gel with ethanol until the washing solution is colorless, then vacuum dry to obtain a phenolic oil-based phenolic organic aerogel (CPA-buty). The density is 0.064 g / cm³. 3 The phenolic resin balls are numerous and evenly distributed. Figure 2 At 90% strain, the compressive strength is 0.43 MPa. Figure 3 The saturated water content is 11 g·g. -1 The water transport rate is 0.048 g·min. -1 ( Figure 4 Under one times the sunlight intensity, the water evaporation rate is 1.71 kg·m³. -2 h -1 ( Figure 5 It is 3.7 times that of pure water.

[0036] Example 4

[0037] Weigh 1.12 g of phenol and 0.48 g of phenolic oil (phenol substitution rate 30%), add them to 30 mL of isopropanol, and stir until dissolved to obtain a mixed solution. Place melamine foam (diameter 3.5 cm, height 4 cm) into the above solution, then add 8 mL of formaldehyde (35 wt%) and 1.5 mL of hydrochloric acid (37 wt%) to obtain a mixed sol. Incubate the mixed sol at 100 °C for 12 h using a solvothermal reaction to obtain a phenolic oil-based phenolic organic gel. Wash the phenolic organic gel with ethanol until the washing liquid is colorless, then vacuum dry to obtain a phenolic oil-based phenolic organic aerogel (CPA-isop). The density is 0.063 g / cm³. 3 The phenolic resin balls are numerous and evenly distributed. Figure 2 At 90% strain, the compressive strength is 0.14 MPa. Figure 3 The saturated water content is 11 g·g. -1 The water transport rate is 0.058 g·min. -1 ( Figure 4 Under one times the sunlight intensity, the water evaporation rate is 1.76 kg·m³. -2 h -1 ( Figure 5 ).

[0038] Example 5

[0039] Weigh 1.12 g of phenol and 0.48 g of phenolic oil (phenol substitution rate 10%), add them to 40 mL of organic solvent (ethanol / isopropanol = 1:1), and stir until dissolved to obtain a mixed solution. Place melamine foam (diameter 3.5 cm, height 5 cm) into the above solution, then add 5 mL of formaldehyde (35 wt%) and 2 mL of hydrochloric acid (37 wt%) to obtain a mixed sol. Incubate the mixed sol at 120 °C for 18 h using a solvothermal reaction to obtain a phenolic oil-based phase-separated phenolic organic gel. Wash the phenolic organic gel with ethanol until the washing liquid is colorless, then vacuum dry to obtain a phenolic oil-based phase-separated phenolic organic aerogel (CPA-et+isop). The density is 0.043 g / cm³. 3 The phenolic resin balls are unevenly distributed. Figure 2 At 90% strain, the compressive strength is 4.3 MPa. Figure 3 The saturated water content is 13 g·g. -1 The water transport rate is 0.078 g·min. -1 ( Figure 4 Under one times the sunlight intensity, the water evaporation rate is 2.01 kg·m³. -2 h -1 ( Figure 5 ).

[0040] The above detailed embodiments provide a specific description of the analytical methods involved in this invention. It should be noted that the above description is only intended to help those skilled in the art better understand the methods and ideas of this invention, and is not intended to limit the scope of the invention. Without departing from the principles of this invention, those skilled in the art can make appropriate adjustments or modifications to this invention, and such adjustments and modifications should also fall within the protection scope of this invention.

Claims

1. A method for preparing a phenol oil-based phase-separated phenolic aerogel, characterized by, The method comprises the following steps: (1) adding phenols and phenolic oil into a mixed solvent, stirring until dissolved to obtain a mixed solution; The mixed solvent is a mixed solvent of ethanol and n-butanol or ethanol and isopropyl alcohol, and the mixed volume ratio is 1:1; The mass ratio of the phenolic oil to the phenols is 1:9-1:1; (2) placing melamine foam into the above solution, and then adding aldehydes and acid to obtain a mixed sol; (3) performing a solvothermal reaction on the mixed sol to obtain a phase-separated phenolic oil-based phenolic organic gel; (4) washing the phenolic organic gel with ethanol, and then vacuum drying to obtain a phase-separated phenolic oil-based phenolic organic aerogel.

2. The method for preparing a phenolic oil-based phase-separated phenolic aerogel according to claim 1, characterized in that, The phenols in step (1) are one of phenol, o-cresol, m-cresol, p-cresol, p-ethylphenol and resorcinol.

3. The method for preparing a phenolic oil-based phase-separated phenolic aerogel according to claim 1, characterized in that, The aldehydes in step (2) are one or two of formaldehyde, paraformaldehyde and furfural; and the acid is one of hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid and oxalic acid.

4. The method for preparing a phenolic oil-based phase-separated phenolic aerogel according to claim 1, characterized in that, The ratio of the phenols, the mixed solvent, the aldehydes and the acid in steps (1) and (2) is 0.8-1.44 g:10-50 mL:1.5-8.5 mL:0.5-2.5 mL.

5. The method for preparing a phenolic oil-based phase-separated phenolic aerogel according to claim 1, characterized in that, The solvothermal reaction temperature in step (3) is 80-160 ℃, and the time is 6-36 h.

6. Application of the phenolic oil-based phase-separated phenolic aerogel prepared by the method of any one of claims 1-5 in solar-driven interfacial water evaporation.

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