NL2030025B1

NL2030025B1 - Method for preparing phenolated lignin-phenolic resin nanospere and application thereof

Info

Publication number: NL2030025B1
Application number: NL2030025A
Authority: NL
Inventors: Liu Yu; Jiang Weikun; Lv Gaojin; Chen Honglei
Original assignee: Univ Qilu Technology
Priority date: 2020-12-28
Filing date: 2021-12-03
Publication date: 2023-05-15
Also published as: NL2030025A; CN112661920A; CN112661920B

Abstract

The present disclosure provides a method for preparing a phenolated lignin-phenolic resin nanosphere and an application thereof. The method comprises phenolation of lignin: mixing lignin or a lignin derivative with phenol and sulfuric acid for reacting in an oil bath, to prepare a phenolated lignin, and condensation reaction of a phenolic resin: mixing the phenolated lignin, phenols, aldehydes and ethanol with deionized water to obtain a mixing solution, and then transferring the mixing solution to a reaction kettle for curing, to obtain the phenolated lignin-phenolic resin nanosphere. Lignin modified by phenolation exhibits extremely high reactivity. The nanosphere with different sizes can be prepared by adding the phenolated lignin in different proportions as a substitute of the phenols for the condensation reaction of the phenolic resin. At the same time, compared with the direct addition of lignin, the use of the phenolated lignin as the substitute of the phenols can greatly improve the stability of the phenolated lignin-phenolic resin nanosphere formed by the polycondensation reaction.

Description

METHOD FOR PREPARING PHENOLATED LIGNIN-PHENOLIC RESIN

NANOSPHERE AND APPLICATION THEREOF

TECHNICAL FIELD

[01] The present disclosure relates to the phenolic materials, and specifically relates to a method for preparing a phenolated lignin-phenolic resin nanosphere and an application thereof.

BACKGROUND ART

[02] Disclosure of the background information is only intended to understand the overall background of the present disclosure better, which 1s not necessarily regarded as an acknowledgement or any form of hint that the information constitutes the prior art known to those ordinarily skilled in the art.

[03] The phenolic resin nanosphere is a kind of high molecular polymers prepared by the polycondensation reaction of phenols and aldehydes (such as formaldehyde, acetaldehyde and the like) under acid or alkali catalysis. Because the phenolic resin has a higher carbon-hydrogen ratio and a unique aromatic ring skeleton structure with rigidity, it has higher thermal stability and excellent mechanical performance. The phenolic resin has currently become an important chemical material widely used in the fields of building materials, energy storage materials, catalyst carriers, biomedical materials and the like.

[04] In recent years, the spherical phenolic resin nanomaterial has received extensive attention due to its excellent chemical stability and high specific surface area.

Particularly, a large number of active phenolic hydroxyl groups in the structure contained on the surface of the spherical phenolic resin nanomaterial make it compounded with many cutting-edge materials to use. For example, in the recent research on a catechol-based phenolic resin, the o-phenol structure can form a reversible chelating force with metal ions, which has a great application potential in the fields of sewage treatment and hydrogels. However, the phenolic resin nanosphere formed by compounding the phenols (such as phenol, resorcinol or catechol) with the aldehydes which are commonly used in the actual production has a large average diameter, usually ranging from a few microns to tens of microns. Moreover, phenol, resorcinol or catechol used as the reactive monomer for the synthesis of the phenolic resin nanosphere has too high cost, which makes its commercial application difficult.

[05] A lignin-modified phenolic resin nanosphere is disclosed in the prior art that an appropriate amount of phenol is substituted with lignin to react with formaldehyde to reduce the particle size of the nanosphere. However, the inventor of the present application found that although the size of the nanosphere is reduced by adding lignin, the nanosphere still has poor stability. And the phenolic resin nanosphere decomposes and cracks when being placed at 200°C, so it cannot be further used under high-temperature conditions, which greatly limits the development of the phenolic resin in high-performance materials. In addition, compared with the phenols (such as phenol, resorcinol or catechol), the active sites of lignin are so fewer that makes less lignin actually participated in the reaction. Therefore, how to improve the reactivity of lignin and increase the ratio of lignin to substitute the phenols is the key to reduce the dosage of the phenols and the production cost. Moreover, improving the stability of the lignin-phenolic resin nanosphere to maintain its high stability in the high-temperature environment is also a technical problem to be solved urgently.

SUMMARY

[06] To overcome the shortcomings in the prior art, the present disclosure is to provide a method for preparing a phenolated lignin-phenolic resin nanosphere and an application thereof. Lignin modified by phenolation exhibits extremely high reactivity.

Meanwhile, the stability of the phenolated lignin-phenolic resin nanosphere formed by the polycondensation reaction is greatly improved.

[07] Specifically, the technical solutions employed by the present disclosure are as follows:

[08] In the first aspect, the present disclosure provides the method for preparing the phenolated lignin-phenolic resin nanosphere, comprising:

[09] phenolation of lignin: mixing lignin or a lignin derivative with phenol and sulfuric acid for reacting in an oil bath, to prepare a phenolated lignin; and

[10] condensation reaction of a phenolic resin: mixing the phenolated lignin, phenols, aldehydes and ethanol with deionized water to obtain a mixing solution, and then transferring the mixing solution to a reaction kettle for curing, to obtain the phenolated lignin-phenolic resin nanosphere.

[11] In the second aspect, the present disclosure provides a phenolated lignin-phenolic resin nanosphere prepared by the above-mentioned method.

[12] In the third aspect, the present disclosure provides an application of the method for preparing the phenolated lignin-phenolic resin nanosphere and/or the phenolated lignin-phenolic resin nanosphere in the preparation of high-performance materials.

[13] One or more technical solutions in the present disclosure have the following beneficial effects:

[14] (1) The low reactivity of lignin results in an extremely low actual loading rate of lignin. And the active sites of lignin for reaction are so fewer that makes too less lignin actually participated in the polycondensation reaction. Phenolation is carried out tor the reaction of lignin with phenol to obtain the phenolated lignin, to improve the reactivity of lignin. The reactivity of lignin is greatly improved due to the increase of its active sites after being modified by phenolation, which possibly makes more lignin stable in the nanosphere.

[15] (2) The existing lignin-modified phenolic resin has poor stability. To reduce the particle size of the phenolic resin and improve the stability of the phenolic resin nanosphere, lignin modified by the phenolation is reacted with the aldehydes to prepare the phenolic resin nanosphere. Lignin modified by the phenolation is rich in phenolic hydroxyl groups, so the content of lignin participating in the polycondensation reaction is further increased, solving the problems that the surface of the phenolic resin nanosphere is loose, and the stability of the phenolic resin nanosphere is greatly improved. Thus, the phenolic resin nanosphere has high stability in an alkaline environment with the temperature of 300-600°C, which promotes the wide application of the phenolic resin in the high-performance materials.

[16] (3) The method has simple preparation and high lignin loading rate, which can obtain the phenolated lignin-phenolic resin nanosphere with high stability and controllable particle size. In addition, the method has low cost and high efficiency, and meets the requirements of green production.

BRIEF DESCRIPTION OF THE DRAWINGS

[17] The drawings as part of the present disclosure are used to further understand the present disclosure, and the exemplary examples and their descriptions of the present disclosure are used to illustrate the present disclosure, not to limit the present disclosure improperly.

[18] Hereinafter, the examples of the present disclosure will be described in detail with reference to the accompanying drawings, in which:

[19] FIG. 1: (a) is a scanning electron micrograph of a catechol-based phenolic resin nanosphere prepared by the method of Example 1 and size distribution thereof; (b) and (c) are size distribution diagrams of the catechol-based phenolic resin nanospheres by adding 30% and 50% of a phenolated lignin respectively in Examples 2 and 3.

Since there are more active sites of lignin after phenolization, more lignin can undergo condensation reaction with aldehydes. At this time, although a dosage of the phenolated lignin reaches 50%, the product can still form the phenolic resin nanosphere. (d), (e) and (f) are particle size distribution diagrams of three kinds of nanospheres detected by dynamic light scattering (DLS), with the particle sizes of 2095 nm, 327 nm and 121 nm in sequence.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[20] The present disclosure will be further described below in conjunction with the specific examples which are only used to illustrate but not to limit the present disclosure. The experimental methods without indicating specific conditions in the following examples are usually in accordance with conventional conditions or in accordance with the conditions recommended by the manufacturer.

[21] Unless otherwise specified, all technical and scientific terms used in the 5 present disclosure have the same meanings as commonly understood by those ordinarily skilled in the art. The reagents or raw materials used in the present disclosure are commercially available. Unless otherwise specified, the reagents or raw materials used in the present disclosure are used in a conventional manner in the art or used in accordance with the product instructions. In addition, any method and material similar or equivalent to the content described in the present disclosure can be applied.

The preferred implementations and materials described in the present disclosure are only used to exemplify.

[22] It shall be noted that the terms used herein are only used to describe the specific examples, not intended to limit the exemplary implementations of the present disclosure. Unless the context clearly indicates to the contrary, the terms used herein in the singular form shall include the plural form. In addition, it shall also be understood that the terms "includes" and/or "including" used in the description shall be deemed to indicate the features, steps, operations, devices, components, and/or combinations thereof.

[23] As described in the background art, the lignin-phenolic resin nanosphere has poor stability, and cannot be further used as the high-performance materials. Lignin is modified by the phenolation to reduce the particle size of the phenolic resin nanosphere while improving its stability.

[24] An implementation of the present disclosure provides the method for preparing the phenolated lignin-phenolic resin nanosphere, including:

[25] phenolation of lignin: mixing lignin or lignin derivative with phenol and sulfuric acid for reacting in the oil bath, to prepare the phenolated lignin; and

[26] condensation reaction of the phenolic resin: mixing the phenolated lignin, phenols, aldehydes and ethanol with deionized water to obtain a mixing solution, and then transferring the mixing solution to the reaction kettle for curing, to obtain the phenolated lignin-phenolic resin nanosphere.

[27] The phenols are partially substituted by lignin modified by the phenolation, to undergo condensation reaction with the aldehydes. Without adding any surfactants or additives, the particle size of the phenolic resin nanosphere is adjusted. More importantly, the phenolated lignin exhibits extremely high reactivity, and the stability of the phenolated lignin-phenolic resin nanosphere formed by polycondensation is improved. The phenolated lignin-phenolic resin nanosphere prepared by the method can be uniformly dispersed in different acid-base solutions and organic solvents, and its stability can be maintained even in a high-temperature alkaline environment.

[28] Further, lignin or the lignin derivative is selected from alkali lignin, lignosulfonate, eutectic solvent extracted lignin, milled wood lignin, and enzymatic/mild acidolysis lignin.

[29] Further, the molar ratio of lignin or the lignin derivative to phenol is 1:1-1:5.

The phenolated lignin at this ratio has the best reactivity, which is conducive to the improvement of the stability of the nanosphere.

[30] Further, the temperature for reacting in the oil bath is 80-100°C, and preferably 90°C, to obtain the best reactivity.

[31] Further, the specific steps for the phenolation of lignin includes: mixing lignin or the lignin derivative with phenol in the molar ratio of 1:1-1:5, then adding 65-75% sulfuric acid to stir, to react in the oil bath for 2-4 h.

[32] Furthermore, the sulfuric acid is preferably 72% sulfuric acid, and the time for reacting in the oil bath 1s preferably 2 h.

[33] Furthermore, after the reaction in the oil bath is completed, the excess phenol is removed by washing with ethyl acetate, and the solid residue is filtered out, to obtain the phenolated lignin.

[34] Further, the phenols are selected from phenol, catechol or resorcinol.

[35] Further, the aldehydes are formaldehyde or acetaldehyde.

[36] Further, the curing is carried out at 100-160°C for 4-8 h, and preferably at

120°C for 6 h.

[37] Further, the proportion of the phenolated lignin in the condensation reaction of the phenolic resin is 10-50 wt%.

[38] Further, in the condensation reaction of the phenolic resin, the mixing solution is heated at 50-70°C for 0.5-2 h, and then at 90-100°C for 20-40 min before transferring to the reaction kettle, and the mixing solution is preferably heated at 65°C for 1 h, and then at 90°C for 30 min before transferring to the reaction kettle. In the process, the etherification efficiency can be effectively improved by gradually increasing the temperature, so that the particle size of the obtained nanosphere is more uniform and stable.

[39] Further, in the condensation reaction of the phenolic resin, the reaction solution obtained is centrifuged after curing, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the phenolated lignin-phenolic resin nanosphere.

[40] An implementation of the present disclosure provides the phenolated lignin-phenolic resin nanosphere prepared by the above-mentioned method. Using the phenolated lignin for the condensation reaction of the phenolic resin can make more lignin to substitute the phenols for reaction, which increases the doping ratio of lignin.

In addition, compared with the phenolic resin nanosphere without adding lignin, the obtained nanosphere has a rougher surface which is very important to increase its specific surface. Meanwhile, this feature is of significance for its application as catalyst carriers and nanomaterial additives.

[41] An implementation of the present disclosure provides an application of the method for preparing the phenolated lignin-phenolic resin nanosphere and/or the phenolated lignin-phenolic resin nanosphere in the preparation of the high-performance materials.

[42] To enable those skilled in the art to understand the technical solutions of the present disclosure more clearly, the technical solutions of the present disclosure will be described in detail below with reference to the specific examples.

[43] Example 1

[44] 1.0 G of catechol is weighed to mix with 0.76 g of 37% formaldehyde solution and 0.0728 g of NaOH thoroughly in the aqueous ethanol solution (80 mL deionized water and 32 mL ethanol) to obtain the mixing solution. The mixing solution is heated at 65°C for 1 h, and then at 90°C for 30 min. Then, the mixing solution is transferred to the sealed stainless-steel autoclave lined with polytetrafluoroethylene to heat at 160°C for 6 h, and then naturally cooled to the room temperature to obtain the reaction solution. The reaction solution is centrifuged at 5000 rpm, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the phenolated lignin-phenolic resin nanosphere.

[45] Example 2

[46] 1.2 G of lignin and 1.2 g of phenol are mixed in the flask, and 72% sulfuric acid is added to stir. Then, the cold water is added to the top of the flask to condense, to react in the oil bath at 90°C for 2 h. After the reaction is completed, the excess phenol is removed using ethyl acetate wash repeatedly, and the solid residue is filtered out, to obtain the phenolated lignin.

[47] 0.3 G of the phenolated lignin and 1.0 g of catechol are weighed to mix with 0.76 g of 37% formaldehyde solution and 0.0728 g of NaOH thoroughly in the aqueous ethanol solution (80 mL deionized water and 32 mL ethanol) to obtain the mixing solution. The mixing solution is heated at 65°C for 1 h, and then at 90°C for 30 min. Then, the mixing solution is transferred to the sealed stainless-steel autoclave lined with polytetrafluoroethylene to heat at 160°C for 6 h, and then naturally cooled to the room temperature to obtain the reaction solution. The reaction solution is centrifuged at 5000 rpm, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the 30% phenolated lignin-phenolic resin nanosphere.

[48] Example 3

[49] 1.2 G of lignin and 1.2 g of phenol are mixed in the flask, and 72% sulfuric acid is added to stir. Then, the cold water is added to the top of the flask to condense,

to react in the oil bath at 90°C for 2 h. After the reaction is completed, the excess phenol is removed using ethyl acetate wash repeatedly, and the solid residue is filtered out, to obtain the phenolated lignin.

[50] 0.5 G of the phenolated lignin and 1.0 g of catechol are weighed to mix with 0.76 g of 37% formaldehyde solution and 0.0728 g of NaOH thoroughly in the aqueous ethanol solution (80 mL deionized water and 32 mL ethanol) to obtain the mixing solution. The mixing solution is heated at 65°C for 1 h, and then at 90°C for 30 min. Then, the mixing solution is transferred to the sealed stainless-steel autoclave lined with polytetrafluoroethylene to heat at 160°C for 6 h, and then naturally cooled to the room temperature to obtain the reaction solution. The reaction solution is centrifuged at 5000 rpm, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the 50 wt% phenolated lignin-phenolic resin nanosphere.

[51] Example 4

[52] 0.3 Gof the unphenolated lignin and 1.0 g of catechol are weighed to mix with 0.76 g of 37% formaldehyde solution and 0.0728 g of NaOH thoroughly in the aqueous ethanol solution (80 mL deionized water and 32 mL ethanol) to obtain the mixing solution. The mixing solution is heated at 65°C for 1 h, and then at 90°C for 30 min. Then, the mixing solution is transferred to the sealed stainless-steel autoclave lined with polytetrafluoroethylene to heat at 160°C for 6 h, and then naturally cooled to the room temperature to obtain the reaction solution. The reaction solution is centrifuged at 5000 rpm, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the lignin-phenolic resin nanosphere. [S3] Example 5 [S4] 0.5 G of the unphenolated lignin and 1.0 g of catechol are weighed to mix with 0.76 g of 37% formaldehyde solution and 0.0728 g of NaOH thoroughly in the aqueous ethanol solution (80 mL deionized water and 32 mL ethanol) to obtain the mixing solution. The mixing solution is heated at 65°C for 1 h, and then at 90°C for 30 min. Then, the mixing solution is transferred to the sealed stainless-steel autoclave lined with polytetrafluoroethylene to heat at 160°C for 6 h, and then naturally cooled to the room temperature to obtain the reaction solution. The reaction solution is centrifuged at 5000 rpm, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the lignin-phenolic resin nanosphere.

[55] Example 6 [S6] 1.2 G of lignosulfonate and 1.2 g of phenol are mixed in the flask, and 65% sulfuric acid is added to stir. Then, the cold water is added to the top of the flask to condense, to react in the oil bath at 80°C for 4 h. After the reaction is completed, the excess phenol is removed using ethyl acetate to wash repeatedly, and the solid residue is filtered out, to obtain the phenolated lignin.

[57] 0.5 G of the phenolated lignin and 1.0 g of resorcinol are weighed to mix with 0.76 g of 37% acetaldehyde solution and 0.082 g of NaOH thoroughly in the aqueous ethanol solution (80 mL deionized water and 32 mL ethanol) to obtain the mixing solution. The mixing solution is heated at 70°C for 2 h, and then at 100°C for 20 min.

Then, the mixing solution is transferred to the sealed stainless-steel autoclave lined with polytetrafluoroethylene to heat at 110°C for 7 h, and then naturally cooled to the room temperature to obtain the reaction solution. The reaction solution is centrifuged at 5000 rpm, then the solid obtained is repeatedly washed with distilled water and ethanol, and dried in the vacuum oven, to obtain the phenolated lignin-phenolic resin nanosphere.

[58] Testing example

[59] 2 G of the phenolic resin nanospheres prepared in examples 1-5 is weighed to soak into 100 mL of the aqueous solution, to heat in the reaction kettle at 100°C and 300°C for 30 min. The state of the phenolic resin nanosphere is recorded as the following table:

[60]

Example 1 | forming sphere with a size of | perfect sphere | perfect sphere 2095 nm

Example 2 | forming sphere with a size of | perfect sphere | perfect sphere 327 nm

Example 3 | forming sphere with a size of | perfect sphere | perfect sphere 121 nm

Example 4 | forming sphere with a size of | perfect sphere | partial sphere 842 nm broken me [notes [

Example 6 | forming sphere with a size of | perfect sphere | perfect sphere 155 nm

[61] The research results show that the phenolic resin nanosphere prepared using the phenolated lignin has extremely high stability, and its spherical structure can be maintained well when adding 50% of the phenolated lignin in a high-temperature environment. On the contrary, the phenolic resin prepared using the unphenolated lignin cannot form nanosphere when adding 50% of the unphenolated lignin.

[62] The above examples are only the preferred examples of the present disclosure, not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the above examples, modifications or equivalent replacements of the technical solutions described in the above examples still can be made by those skilled in the art. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

S12 - Conclusions

A method for preparing a phenolic lignin phenolic resin nanosphere, the method comprising: lignin phenolation: mixing lignin or a lignin derivative with phenol and sulfuric acid for reaction in an oil bath to prepare a phenolic lignin; and condensation reaction of a phenolic resin: mixing the phenolic lignin, phenols, aldehydes and ethanol with deionized water to obtain a mixing solution, and then transferring the mixing solution to a reaction kettle for curing, to obtain the phenolic lignin phenolic resin nanosphere.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein lignin or the lignin derivative is selected from alkali lignin, lignosulfonate, eutectic solvent extracted lignin, ground wood lignin and enzymatic/mildeacidolysis lignin, and a molar ratio of lignin or the lignin derivative to phenol is 1:1 — is 1:5.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein a temperature for reacting in the oil bath is 80-100°C, and preferably 90°C.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein specific steps for the phenolation of lignin comprises: mixing lignin or the lignin derivative with phenol in the molar ratio of 1:1 - 1:5, then adding 65 — 75% sulfuric acid for stirring, and reacting in the oil bath for 2 — 4 h; wherein the sulfuric acid is preferably 72% sulfuric acid, and a reaction time in the oil bath is preferably 2 hours; wherein, after the reaction in the oil bath is completed, an excess of phenol is removed by washing with ethyl acetate, and a solid residue is filtered off, to obtain the phenolated lignin.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein the phenols are selected from phenol, catechol or resorcinol, and the aldehydes are formaldehyde or acetaldehyde.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein the curing is performed at 100-160°C for 4-8 hours, and preferably at 120°C for 6 hours; wherein a portion of the phenolic lignin in the condensation reaction of the phenolic resin is 10-50% by weight.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein in the condensation reaction of the phenolic resin, the mixing solution is heated at 50-70°C for 0.5-2 hours, and then at 90-100°C for 20-40 min before transfer to the reaction kettle; and the mixing solution is preferably heated at 65°C for 1 hour, then at 90°C for 30 minutes before being transferred to the reaction kettle.

The method for preparing the phenolic lignin phenolic resin nanosphere according to claim 1, wherein in the condensation reaction of the phenolic resin, a reaction solution obtained after curing is centrifuged, then a solid obtained is repeatedly washed with distilled water and ethanol, and dried in a vacuum oven, to obtain the phenolic lignin phenolic resin nanosphere.

A phenolic lignin phenolic resin nanosphere, wherein the phenolic lignin phenolic resin nanosphere has been prepared according to the method of any one of claims 1-8.

Use of the method of any of claims 1-8 and/or the phenolated lignin phenolic resin nanosphere of claim 9 in the preparation of high performance materials.