KR20230059363A - Manufacturing method of polymer monomer using lignin - Google Patents

Abstract

The present invention relates to a method for manufacturing a polymer monomer, which is plastic precursors, from all materials produced by a hydrothermal reaction of lignin, a by-product generated during pulp production and biofuel production. The method of manufacturing a polymer monomer comprises the steps of: extracting guaiacol from liquid water-soluble oil produced through a lignin decomposition reaction; manufacturing a carbon structure by converting a product obtained from residual lignin oil and solid residue; and producing caprolactam and adipic acid, which are monomers of nylon, from guaiacol using a metal-supported catalyst on the carbon structure. Accordingly, a method of utilizing 100 % of waste lignin discharged from industry as a catalyst support and plastic production precursor is proposed.

Description

Manufacturing method of polymer monomer using lignin {Manufacturing method of polymer monomer using lignin}

The present invention relates to a method for producing a polymer monomer used in a process for producing nylon using a product obtained through a hydrothermal reaction of lignin.

Lignin is a major component of biomass, which makes up 15-35% of wood, and is a biopolymer rich in aromatic substances. Lignin obtained from biomass has different components and additives depending on the extraction method. Natural lignin can be obtained by purely extracting lignin, but industrially classified and recovered as waste resources remaining after utilization such as pulp processing and biomass fuel extraction, most of which are burned as a heat source, and only some are recycled. In the papermaking process, lignin and hemicellulose are removed to produce white pulp, and the kraft pulping process is mainly used for this purpose. This process, which accounts for about 90% of the pulp production process, uses a solution of sodium hydroxide and sodium sulfide to cook the wood at 150-180 °C to break the bonds between cellulose, hemicellulose and lignin. The separated cellulose is used as pulp, and the remaining hemicellulose and lignin are separated into black liquor. The lignin separated by treating the black liquor is called kraft lignin. However, compared to natural lignin, kraft lignin has fewer C-O bonds that are easy to depolymerize and a large amount of C-C bonds that are difficult to depolymerize, making it difficult to convert into high value-added chemical materials. In addition, in the biofuel production process using biomass, lignin is removed through sulfuric acid treatment and hydrolysis. It is difficult to treat as a waste with low utilization because it contains

Lignin is a polymer produced by combining various aromatic compounds, and a lot of development of aromatic monomer production technology using this has been progressed. Various depolymerization processes have been studied to convert lignin into high-value compounds. Aromatic compounds can be produced through depolymerization using supercritical water or supercritical alcohol, base-catalyzed depolymerization, oxidative depolymerization, and hydrocracking using a catalyst and high-pressure hydrogen. . However, even when depolymerization is performed with the above technique, (1) the yield of monomers is low due to the tight C-C bond of lignin, and (2) non-selective depolymerization occurs because lignin has various bonds, resulting in low product selectivity. Therefore, in order to produce a monomer with high selectivity, various processes such as separation/purification/extraction must be added in addition to the depolymerization process, so this method has a disadvantage of poor economic efficiency.

In addition to studies on converting lignin into monomers using enzymes and catalytic processes, many technologies for converting lignin into carbon materials have been developed. In previous studies, examples of manufacturing various carbon structured materials including porous activated carbon by extracting lignin from black liquor produced after the pulping process can be examined. However, carbon products produced through pyrolysis and hydrothermal carbonization have a small specific surface area and it is difficult to control the shape of carbon, which limits the production and utilization of high-quality carbon.

Industrially, waste lignin is discharged in significant amounts through processes for pulp production and biofuel, but lignin contains a large amount of contaminants, and because of its complex structure, upgrading technology to high value-added compounds is very limited. this is urgent

Korean Registered Patent No. 10-2157512 (2020.09.18. Publication)

The present invention provides a method for preparing a catalyst using a material extracted from lignin and preparing a plastic precursor using the catalyst and an aromatic compound extracted from lignin.

In order to achieve the above object, the present invention comprises the steps of extracting water-soluble oil, lignin oil, and solid residue from lignin (first step); Preparing a carbon structure using at least one of the lignin oil and the solid residue (second step); preparing a catalyst by mixing the prepared carbon structure and a metal precursor (third step); and preparing a polymer monomer using the water-soluble oil and the prepared catalyst (fourth step).

The present invention can prepare a catalyst important for converting lignin from an aromatic compound into a monomer by preparing a polymer monomer for producing nylon using water-soluble oil, lignin oil, and solid residue obtained through hydrothermal reaction of lignin, , 100% of lignin waste can be utilized.

1 is a schematic diagram of the entire method for producing a polymer monomer according to the present invention, which includes a process of synthesizing a carbon support from lignin and a process of preparing a lignin-derived nylon monomer.
Figure 2 is a schematic diagram showing the step of separating water-soluble oil, lignin oil, and solid residue through hydrothermal reaction of lignin in the first step of the present invention.
3 is a schematic diagram showing a nanocasting method for manufacturing the porous carbon structure (lignin-derived porous carbon; LPC) of the present invention.
4 is a result of 13C-1H heteronuclear single quantum coherence experiment by nuclearmagnetic resonance (HSQC NMR) by nuclear magnetic resonance of kraft lignin and clason lignin.
5 is a scanning electron microscopy (SEM) image of porous carbon (LPC) and lignin-derived carbon (LC) produced from lignin.
6 is an X-ray diffraction (XRD) analysis result of a catalyst supported with 10 wt% MoO ₂ and a catalyst supported with 1 wt% Pd on various carbon supports.
7 shows scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy of a catalyst loaded with 10 wt% MoO ₂ and 1 wt% Pd on LPC. EDS) is an elemental analysis image.
8 is a transmission electron microscopy (TEM) image of a catalyst supported with 10 wt% MoO ₂ on various carbon supports.
9 is a TEM image of catalysts supported with 1 wt% Pd on various carbon supports.
10 is a hydrodeoxygenation (HDO) reaction result of guaiacol using a carbon catalyst supported with 10 wt% MoO ₂ .
11 is a result of hydrodeoxygenation catalytic reaction of lignin-derived water-soluble oil in the presence of MoO ₂ /LPC catalyst.
12 is a result of hydrogenation of phenol in a carbon catalyst supported with 1 wt% Pd.

Hereinafter, the present invention is described in detail.

The object of the present invention is to separate (1) carbon materials from waste lignin discharged from industrial processes as well as purely extracted lignin to prepare high surface area carbon structures, (2) technology to extract lignin-derived guaiacol, and ( 3) It is to provide a catalytic conversion process for producing nylon raw materials including caprolactam and adipic acid from guaiacol.

In addition, the feature of the present invention is a technology that utilizes 100% lignin, and the carbon extracted from lignin is applied as a catalyst material in the catalyst process for producing caprolactam / adipic acid, a raw material of nylon polymer, from lignin-derived aromatic extract. Thus, waste can be drastically reduced.

Through the present invention, (1) a technology for extracting guaiacol from lignin, (2) a catalytic process technology for producing caprolactam and adipic acid from guaiacol, and (3) a catalyst necessary for this, using the lignin residual extract Methods for 100% utilization of waste lignin as catalyst carriers and precursors for plastic production, such as manufacturing technology and (4) technology for producing porous carbon structures with high surface area from lignin, are presented.

The present invention comprises the steps of extracting water-soluble oil, lignin oil, and solid residue from lignin (first step); Preparing a carbon structure using at least one of the lignin oil and the solid residue (second step); preparing a catalyst by mixing the prepared carbon structure and a metal precursor (third step); and preparing a polymer monomer using the water-soluble oil and the prepared catalyst (fourth step).

1 is a schematic diagram showing a method for preparing a polymer monomer according to the present invention. Specifically, after preparing a carbon structure from lignin oil and solid residue, a catalyst is prepared by supporting a metal or metal oxide, and then extracting guaiacol from the water-soluble oil and reacting with the prepared catalyst to obtain caprolactam and adip. Indicates the process of making an acid.

The first step is a step of decomposing lignin to extract water-soluble oil, lignin oil and solid residue from lignin.

Specifically, the first step is to hydrothermally react a mixture of lignin with a catalyst and a first solvent at a temperature of 200 to 400 ° C. or 250 to 350 ° C. for 30 minutes to 2 hours or 30 minutes to 1 hour to obtain water-soluble oil. , lignin oil and solid residues can be extracted.

The lignin includes at least one selected from the group consisting of extracted lignin and waste lignin. Specifically, the lignin may be extracted pure lignin or waste lignin. More specifically, the lignin may be waste lignin pulverized in a powder form.

The catalyst of the first step includes at least one selected from the group consisting of potassium carbonate, potassium hydroxide, sodium carbonate, calcium carbonate, and magnesium carbonate, and the first solvent may include water, ethanol, or other alcohol. Specifically, the catalyst may be potassium carbonate. The first solvent may be water.

In the first step, lignin and catalyst may be mixed in a weight ratio of 5 to 20: 1 or 10 to 15: 1.

Specifically, as shown in FIG. 2, the first step is to add the hydrothermal reaction mixture to pH 3 or less or pH 2 using an acid solution, precipitate lignin, and filter the precipitated lignin through a filter. After obtaining the solid residue, obtaining a water-soluble oil from the filtered aqueous solution using an organic solvent, dispersing the solid residue in acetone, filtering out the solid residue, and heating at 50 to 70 ° C. to extract lignin oil. At this time, the acid solution may be hydrochloric acid, and the organic solvent may be toluene.

The second step is a step of preparing a carbon structure using the lignin oil and the solid residue. Specifically, as shown in FIG. 3, the second step is to prepare a silica-lignin composite by dissolving lignin oil and silica, carbonizing the silica-lignin composite, and then etching the silica to prepare a carbon structure. there is.

The second step may include drying a solution in which the lignin oil and silica are dissolved in a second solvent to prepare a silica-lignin complex; and preparing a carbon structure by carbonizing the silica lignin oil composite at 600 to 1200° C. for 1 to 5 hours.

In the step of preparing the silica-lignin complex, spherical silica is used, and a solution in which the lignin oil and silica are dissolved in a second solvent at a weight ratio of 1:1 to 4 is stirred, and then completely dried at room temperature to silica- A lignin complex can be prepared.

In the step of preparing the carbon structure, the silica-lignin composite is heated at a rate of 1 to 5 ° C / min under nitrogen conditions and carbonized at 600 to 1200 ° C or 800 to 1000 ° C for 1 to 5 hours or 1 to 3 hours A carbon structure can be produced.

The step of preparing the carbon structure is carried out by repeating the etching process of dissolving the silica by putting the carbonized silica-lignin complex in a 1-3 M basic aqueous solution and maintaining it at 50-100 ° C for 1-2 hours. can Through this etching process, the silica spheres can be removed from the silica-lignin complex.

The carbon structure prepared from the lignin oil is a porous carbon structure, the porous carbon structure may be a lignin-derived porous carbon, and the total pore volume of the porous carbon structure is 2 to 50 cm ³ /g or 2 to 20 cm ³ / can be g.

Alternatively, in the second step, the solid residue is heated at a rate of 1 to 5° C./min under nitrogen conditions and carbonized at 600 to 1200° C. or 800 to 1000° C. for 1 to 5 hours or 1 to 3 hours to form a carbon structure. It includes manufacturing steps.

Then, after washing the prepared carbon structure, putting it in an aqueous nitric acid solution, stirring for 1 to 15 hours, and then washing with water may be further included. Through this process, the surface of the carbon structure exhibits hydrophilicity, which can be activated so that metal or metal oxide can be easily supported on the carbon surface.

The third step is a step of preparing a catalyst by binding a metal or metal oxide to the prepared carbon structure.

In the third step, a catalyst may be prepared by dissolving the carbon structure and the metal precursor in distilled water at a mass ratio of 2 to 20:1 and drying at a temperature of 30 to 200 ° C.

The metal precursor includes a precursor of at least one metal selected from the group consisting of molybdenum, tungsten, vanadium, palladium, platinum, rhodium, ruthenium, iridium, manganese, iron, cobalt, and nickel having structures of metal salts and metal oxides. Specifically, molybdenum hexacarbonyl, molybdate chloride, ammonium molybdenum oxide, metavanadic acid, ammonium tungsten, molybdenum chloride, tungsten vanadium chloride, palladium chloride, platinum chloride, rhodium chloride, ruthenium chloride, iridium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, palladium nitrate, platinum nitrate, rhodium nitrate, ruthenium nitrate, iridium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, and hydrates thereof.

The dried catalyst is in powder form, heated at a rate of 1 to 5° C./min under nitrogen conditions, heat treated at 300 to 600° C. for 1 to 5 hours, heated at a rate of 1 to 5° C./min under hydrogen conditions, and heated at 500° C./min. A metal or metal oxide may be supported on the carbon structure by additionally performing at least one heat treatment among the heat treatment at ~800° C. for 1 to 5 hours.

As described above, the carbon support of the present invention supports metals or metal oxides such as molybdenum oxide (MoO ₂ ) and palladium (Pd) to catalyze phenol conversion hydrodeoxygenation of guaiacol and phenol cyclolysis, respectively. It is used as a catalyst for cyclohexanone/cyclohexanol conversion hydrogenation and can exhibit high reactivity and selectivity.

The fourth step is a step of preparing a polymer monomer by reacting a lignin-derived catalyst with a water-soluble oil, including hydrodeoxygenation of guaiacol contained in the water-soluble oil; hydrogenation of phenol; And a polymer monomer may be prepared through a conversion reaction of aromatic hydrocarbons.

The fourth step may include preparing phenol by mixing the water-soluble oil and the prepared catalyst and stirring at a rate of 300 to 1000 rpm under a hydrogen pressure of 10 to 50 bar; Preparing a cyclic hydrocarbon compound by mixing the prepared phenol with a metal catalyst, stirring at a rate of 300 to 1000 rpm under a hydrogen pressure of 3 to 10 bar, and then reacting at 50 to 100 ° C. for 1 to 5 hours; and preparing a polymer monomer using the prepared cyclic hydrocarbon compound and an acid catalyst.

The polymer monomer prepared in the fourth step includes at least one selected from the group consisting of caprolactam and adipic acid.

The water-soluble oil includes at least one selected from the group consisting of guaiacol and creosol, and the water-soluble oil may be guaiacol.

The step of preparing phenol is a step of preparing phenol from guaiacol through hydrodeoxygenation of guaiacol contained in water-soluble oil.

The water-soluble oil and the prepared catalyst may be mixed in a mass ratio of 0.5 to 1.5:1 or 0.5 to 1.0:1.

The step of preparing the cyclic hydrocarbon compound includes at least one selected from the group consisting of cyclohexanol and cyclohexanone from phenol through hydrogenation of phenol.

In the step of preparing the polymer monomer, cyclohexanol may produce adipic acid and cyclohexanone may produce caprolactam through a conversion reaction of aromatic hydrocarbons by reacting with an acid catalyst. The adipic acid is a raw material of nylon-6.6, and caprolactam is a raw material of nylon-6.

In the step of preparing the polymer monomer, caprolactam or adipic acid may be prepared by mixing with the prepared aromatic hydrocarbon compound acid catalyst and heating at 50 to 200 ° C.

The acid catalyst includes at least one selected from the group consisting of trifluoroacetic acid, nitric acid, and boron trifluoride diethyl etherate.

Specifically, when the aromatic hydrocarbon compound is cyclohexanone, caprolactam may be prepared by mixing cyclohexanone with an acid catalyst, heating at 50 to 100° C., and then reacting with hydroxylamine for 3 to 5 hours.

In addition, cyclohexanone is reacted with hydroxylamine sulfate or hydroxylamine phosphate to generate cyclohexanone oxime, which is extracted and separated with a solvent such as toluene, and then extracted with a solvent such as benzene by adding oleum. After treatment with ammonia, caprolactam can be produced.

When the aromatic hydrocarbon compound is cyclohexanol, adipic acid may be produced by mixing cyclohexanol and nitric acid and heating at 50 to 200°C.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for explaining the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples according to the gist of the present invention. .

<Example 1> Lignin decomposition using hydrothermal reaction

Kraft lignin, which corresponds to waste lignin, used lignin discharged from the pulp process or lignin purchased from Sigma-Aldrich without separate treatment. The lignin released during the separation of sugar components containing pentose and hexose was used. After dispersing 20 g of waste lignin pulverized in powder form and 2 g of K ₂ CO ₃ , which serves as a catalyst, in 100 mL of water by stirring as much as possible (mass ratio of lignin and K ₂ CO ₃ is 10:1), It is put into an autoclave reactor for hydrothermal reaction. After purging the inside of the reactor with nitrogen, the temperature inside the reactor was raised to 300° C. without applying additional gas pressure, and then maintained for 40 minutes. After the reaction, lignin is precipitated while slowly adding hydrochloric acid to the solution recovered from the reactor cooled to room temperature until the pH is about 2. When the precipitated lignin is filtered through a filter, a solid residue with lignin oil remains on the filter paper, and the aqueous solution exiting the filter contains water-soluble oil. Water-soluble oil can be extracted with an organic solvent such as toluene. The filtered aqueous solution is first extracted with water-soluble oil using 20 mL of toluene. As a result of gas chromatography and gas chromatography-mass spectrometry analysis, about 40 mol% of guaiacol was produced. As a result of titrating the amount of guaiacol, about 0.5 mmol of guaiacol was obtained from 20 g of acid-treated lignin. In terms of mass, about 0.06 g of guaiacol was produced. In the case of lignin oil, the solid component remaining on the filter paper when the aqueous solution is filtered is dispersed in acetone to extract the oil. Filtering the suspension gives a black liquid, and heating the solution on a hot plate to a temperature of about 55 °C to evaporate the acetone produces a sticky solid lignin oil. In addition, the solid remaining on the filter paper is undecomposed lignin, which is completely dried in an oven and used as a solid residue for the production of lignin-derived carbon (LC).

< Example 2> Derivation of lignin using lignin oil porous carbon (lignin-derived porous carbon, LPC) synthesis

Silica spheres (10 g) having a uniform size are mixed with a solution in which about 4 g of lignin oil is dissolved in 40 mL of acetone, and then completely dried at room temperature. The completely dried silica-lignin oil complex was heated at a rate of 2 °C/min under nitrogen conditions and carbonized at 900 °C for 2 hours to form a carbon structure. The silica spheres are removed from the silica-carbon composite by repeating an etching process in which the silica is dissolved by holding the silica 4-5 times. Then, when the pH of LPC is lowered to neutral by washing several times with distilled water (DI water), LPC, a porous carbon structure in which the stacked spheres are removed, is synthesized. Then, nitric acid treatment is performed to make the surface of the carbon carrier hydrophilic. An aqueous solution of nitric acid was poured into the LPC, stirred for about 12 hours, and then washed with water to adjust the pH to neutral. Through this process, it is activated in a situation where it is easy to support metal or metal oxide on the carbon surface. The LPC thus produced supports MoO ₂ and Pd and is used as a catalyst.

< Example 3> solid residue Synthesis of lignin-derived carbon (LC)

The dried solid residue was heated to 900 °C at a heating rate of 2 °C/min under nitrogen conditions in the same manner as in the LPC synthesis of Example 2, and then carbonized for 2 hours. Then, use a mortar-pestle to pulverize the carbon product more finely. LC was prepared by acid-treating the carbon surface with an aqueous solution of nitric acid for about 12 hours and then washing with distilled water to adjust the pH to neutral.

<Example 4> Catalyst synthesis in which metal particles are supported on a carbon carrier

An impregnation method was used to prepare a catalyst in which molybdenum was supported on a carbon support. At this time, three types of carbon supports were used: AC, LC, and LPC. When the mass ratio of carbon to molybdenum (NH ₄ )6Mo ₇ O ₂₄ .4H ₂ O is adjusted to 5:1, about 10 wt% Mo catalyst can be synthesized. The Mo precursor is used by dissolving it in a small amount of distilled water, and the amount of water is determined by referring to the total pore volume value shown in the BET plot (see Table 1).

Catalyst S _BET (m ² /g) V _P (cm ³ /g) D _P (nm) AC 868.1 0.7 3.1 LPC 626.0 3.4 21.5 LC 236.4 0.1 2.2

After dissolving (NH ₄ )6Mo ₇ O ₂₄ ·4H ₂ O in distilled water in an amount corresponding to the total volume of pores of the carbon support, the solution was sufficiently absorbed into the carbon support using a mortar and pestle, and then dried in an oven at 60 °C. The dried powder was heated at a rate of 2 °C/min under nitrogen conditions and then heat-treated at 500 °C for 3 hours. Subsequently, the temperature was raised at a rate of 2 °C/min under 4% hydrogen conditions and heat-treated at 600 °C for 3 hours to complete three catalysts in which MoO ₂ was supported on carbon (MoO ₂ /LPC, MoO ₂ /LC, MoO ₂ /AC).

The process of making a catalyst in which palladium is supported on a carbon support is as follows. After dissolving Pd(NO ₃ ) ₂ ·xH ₂ O in acetone in an amount corresponding to 1 wt% Pd, the carbon support was dispersed in the Pd solution and stirred for 24 hours in a sealed state. After opening the lid, the mixture is stirred for 24 hours to evenly disperse Pd ions in the carbon support while evaporating acetone. The completely dried powder was heated at a rate of 5 °C/min to 200 °C under 4% hydrogen conditions, and maintained at 200 °C for 4 hours.

<Example 5> Production of caprolactam using guaiacol extracted from lignin

The aqueous fraction extracted from the aqueous solution produced by the hydrothermal reaction of lignin using toluene as a solvent contains about 40 mol% of guaiacol and contains methylcyclohexane, xylene, creosol, and some polycyclic aromatic hydrocarbons. To compare the activities of MoO ₂ catalysts synthesized using various carbon supports, 2 mmol of guaiacol was dissolved in 20 mL of toluene, decane was added as an internal standard, and 100 mL scale The catalytic reaction was carried out in an autoclave reactor. Each catalyst was used in an amount of 0.2 g, and after purging the inside of the reactor with hydrogen, the hydrogen pressure was filled at 30 bar and the solution was stirred at about 600 rpm. The MoO ₂ catalyst significantly selectively removed the methoxyl group from guaiacol to obtain phenol with high selectivity, and it was shown that a significant amount of cresol with a methyl group attached to phenol was also produced. In addition, a small amount of Enisol from which the hydroxyl group of guaiacol was removed was produced, and a small amount of benzene from which both methoxyl and hydroxyl groups were removed was also produced.

Produced phenol can be converted into KA-oil using a Pd catalyst. KA-oil is a mixture of cyclohexanol and cyclohexanone. 0.2 g of the synthesized 1 wt% Pd catalyst was put into a 100 mL autoclave with an aqueous solution of 2 mmol of phenol and 20 mL of distilled water, then purged with hydrogen, filled to 5 bar, and stirred at 600 rpm. And after raising the temperature to 80 ° C., the reaction proceeded for 3 hours. Looking at the catalytic reaction pathway, phenol becomes cyclohexanone as an intermediate product and is converted to cyclohexanol as the final product over time. In order to obtain the maximum yield of cyclohexanone, the catalytic reaction must be carried out for a short time with a highly efficient catalyst because the intermediate product must be finished before further reaction proceeds.

Cyclohexanone thus produced is converted into caprolactam through a cascade reaction. Put 20.1 mL of trifluoroacetic acid, which serves as an acid catalyst and solvent, and 1.9 mL of acetonitrile as an additive into a vial, heat it to 70-75 ° C, and then add 0.8 mL of cyclohexanone and 0.4 mL of hydroxylamine as one of the reactants. was added and the reaction proceeded for about 4 hours, showing a cyclohexanone conversion rate of 99.9% or more and high caprolactam selectivity (> 99.9%). Through the proposed three catalytic reactions (hydrodeoxygenation of guaiacol, hydrogenation of phenol, and conversion of cyclohexanone), guaiacol extracted from lignin can be converted to caprolactam, a monomer of nylon-6. .

The produced cyclohexanol is reacted with a concentrated nitric acid solution at elevated temperatures (50-200 ° C) to produce adipic acid. Adipic acid can be converted to nylon-6,6. After raising the temperature of the oil bath to 55-60 ° C, a round bottom flask containing 2 mL of concentrated nitric acid solution is heated while stirring in the oil bath. After stabilizing the temperature of the concentrated nitric acid solution for about 10 minutes, 1 mL of cyclohexanol is injected very slowly using a syringe, followed by stirring at 55-60 ° C for about 30 minutes. Thereafter, the temperature of the oil bath is raised to about 100° C. and maintained for 5 minutes. After the reaction is completed, the solution is cooled to room temperature, about 20° C., and then put into a bath containing ice water to precipitate adipic acid. Precipitated adipic acid is obtained using a filter, and nitric acid attached to adipic acid is washed with distilled water cooled to 5 ° C or less and then removed through a filter. When the produced adipic acid is dried in an oven at a temperature of 80 ° C., it can be confirmed that adipic acid is produced.

Experimental Example 1

The lignin used in the experiment used waste lignin obtained as a residue after use in a commercial process, but lignin extracted by other methods can also be applied. The two main types of lignin used in the experiment were kraft lignin, obtained as a by-product during the pulp manufacturing process, and classone lignin, which is released after obtaining cellulose containing sugar during the biofuel extraction process. 13C-1H HSQC NMR was analyzed for component analysis of the two lignins, and the results are shown in FIG. 4 . Referring to Figure 4, it can be seen that kraft lignin includes aromatic compounds of various bonds. On the other hand, in the case of biofuel and Clason lignin released during the sugar extraction process, it was found that polysaccharides were included to some extent. The two lignins undergo a hydrothermal reaction under the same method and conditions to produce lignin oil.

The results of 13C-1H HSQC NMR analysis measured after evaporating acetone from lignin oil obtained through hydrothermal reaction showed that the guaiacyl group occupied most of the lignin oil extracted from the two types of lignin. It can be seen that bio-oil having similar components is extracted after hydrothermal reaction even when two lignins are used.

Experimental Example 2

The LPC prepared in Example 2 and the LC prepared in Example 3 were photographed with a scanning electron microscope (SEM), and the results are shown in FIG. 5.

LPC is prepared through nanocasting using well-sized silica spheres as a template and lignin oil extracted from lignin as a carbon source (see FIG. 2). LC is produced by carbonization of the undissolved solid residue during the hydrothermal process of lignin. The solid residue is produced as LC when it is carbonized at high temperature under nitrogen conditions, and acid treatment is performed using nitric acid to activate the surface to prepare a highly dispersed catalyst.

When MoO ₂ was supported on the carbon support, an impregnation method (incipient wetness impregnation, IWI) was used. After dissolving the molybdenum precursor in distilled water in an amount corresponding to the total volume of pores of the support, the solution was sufficiently absorbed into the support using a mortar and pestle, and then dried. The dried powder was heat-treated at high temperature (400-900 ° C) under nitrogen conditions and then subjected to high-temperature reduction with hydrogen (400-900 ° C) to prepare a supported catalyst.

In addition, in order to confirm the characteristics of the catalyst according to the type of activated carbon, XRD analysis, STEM imaging, EDS analysis, and TEM imaging were performed on MoO ₂ /LC, MoO ₂ /AC, and MoO ₂ /LPC, and the results are shown in Fig. 6 to 8 are shown.

Through the XRD shown in FIG. 6 and the STEM and EDS of FIG. 7, it can be confirmed that MoO ₂ /LPC having a molybdenum content of 10 wt% in LPC has very well dispersed MoO ₂ . Looking at the TEM image of FIG. 8, MoO ₂ /LC and MoO ₂ /AC prepared using LC and activated carbon showed a larger size of MoO ₂ nanoparticles than MoO ₂ /LPC.

When Pd is supported on the carbon support, catalyst powder is obtained by putting the carbon support in a suspension in which the Pd precursor is dispersed in acetone and slowly evaporating the acetone. The catalyst was synthesized by heat treatment (100-400 °C) under hydrogen conditions, and the synthesized catalyst was analyzed by XRD and photographed by TEM, and the results are shown in FIGS. 6(b) and 9. Looking at (b) of FIG. 6, the distribution of metal Pd particles in the reduced catalyst (1 wt% Pd) is confirmed through XRD. Comparing the palladium particle size of 1 wt% Pd catalyst synthesized using different types of carbon supports through the TEM image of FIG. 9, Pd/LPC shows very small Pd nanoparticles, and Pd/AC and Pd/LC show Large Pd particles were observed.

Experimental Example 3

As the size of the metal particles supported on the catalyst is small and spread evenly, the number of active sites on the metal surface increases, increasing the catalytic activity. It can be confirmed through the fact that the metal particle-supported catalyst exhibits better catalytic activity than the comparative group.

First, in the hydrodeoxygenation reaction of guaiacol (GUA) shown in FIG. 10 (the catalytic reaction is carried out at a temperature of 320 ° C. for 2 hours using a toluene solvent under a hydrogen condition of 30 bar), the dispersion of molybdenum is relatively poor When MoO ₂ /AC and MoO ₂ /LC catalysts were used, conversion rates of 81.7% and 12.2%, respectively, were obtained in the hydrodeoxygenation of guaiacol. And MoO ₂ /LPC in which MoO ₂ was well dispersed showed a conversion rate of 98.4% under the same conditions. And in terms of selectivity, all catalysts except MoO ₂ /LC showed a phenol selectivity of about 74-76%, and cresol in the form of adding one methyl group to phenol showed a selectivity of about 12-16% (Enisol and benzene appear to account for about 10%).

As a result of catalytic hydrodeoxygenation of the lignin-derived water-soluble fraction shown in FIG. 11 in the presence of a MoO ₂ /LPC catalyst, a conversion rate of 98% or more was shown under the MoO ₂ /LPC catalyst. In addition, in terms of selectivity, it was confirmed that phenol selectivity was about 60%, cresol in which one methyl group was added to phenol showed about 25% selectivity, and enisole and benzene each accounted for less than 5%.

12 shows a hydrogenation reaction for converting phenol, a major product produced in the hydrodeoxygenation reaction of guaiacol, into cyclohexanone and cyclohexanol. In the presence of a palladium catalyst dispersed on a carbon support, water as a solvent was reacted under 5 bar hydrogen at 80 °C for 3 hours, and catalytic activity and selectivity were compared. Pd/AC and Pd/LC showed conversion rates of 42.5% and 57.7% in phenol hydrogenation. On the other hand, Pd/LPC showed an improved conversion rate of 79.4%. This proves that high catalytic activity is shown in Pd/LPC having a high dispersion of Pd. The selectivity of the product is high for the intermediate product cyclohexanone at the beginning of the reaction, but as the conversion rate increases, the selectivity of the final product cyclohexanol tends to increase. As the reaction time increases, the selectivity of the final product cyclohexanol increases. has increased. When the reaction time was kept short (about 2 hours) using Pd/LPC with good catalytic activity, the conversion rate was about 80% and the selectivity of cyclohexanone was 85%. Since Pd/LC showed slightly higher catalytic activity than Pd/AC, it proves that LC is useful as a catalyst support even though it has a relatively low surface area.

The resulting cyclohexanone is converted into caprolactam when reacted in the presence of trifluoroacetic acid as a solvent and catalyst, hydroxylamine as a reactant, and acetonitrile as an additive. When the reaction proceeds for about 4 hours at a temperature of about 70-75 ° C., caprolactam is produced with a conversion rate of 99.9% or more and a selectivity of 99.9% or more.

The produced cyclohexanol is reacted with a concentrated nitric acid solution at elevated temperatures (50-200 ° C) to produce adipic acid. Caprolactam can be used as a raw material for nylon-6, and adipic acid can be used as a raw material for nylon-6 and 6, respectively.

Having described specific parts of the present invention in detail above, it is clear that these specific techniques are only preferred embodiments for those skilled in the art, and the scope of the present invention is not limited thereto. Accordingly, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims (12)

Extracting water-soluble oil, lignin oil, and solid residue from lignin (first step);
Preparing a carbon structure using at least one of the lignin oil and the solid residue (second step);
preparing a catalyst by mixing the prepared carbon structure and a metal precursor (third step); and
A method for producing a polymer monomer comprising the step (fourth step) of preparing a polymer monomer using the water-soluble oil and the prepared catalyst. According to claim 1,
The lignin is a method for producing a polymer monomer comprising at least one selected from the group consisting of extracted lignin and waste lignin. According to claim 1,
The first step is to extract water-soluble oil, lignin oil and solid residue through a hydrothermal reaction of a mixture of lignin with a catalyst and a first solvent at a temperature of 200 to 400 ° C for 30 minutes to 2 hours. A method for producing a polymeric monomer. According to claim 1,
The second step may include drying a solution in which the lignin oil and silica are dissolved in a second solvent to prepare a silica-lignin complex; and
Method for producing a polymer monomer comprising the step of preparing a carbon structure by carbonizing the silica-lignin complex at 600 to 1200 ° C. for 1 to 5 hours. According to claim 4,
The prepared carbon structure is a porous carbon structure,
The method for producing a polymer monomer, characterized in that the total pore volume of the porous carbon structure is 2 to 50 cm ³ /g. According to claim 1,
The second step is a method for producing a polymer monomer comprising the step of preparing a carbon structure by carbonizing the solid residue at 600 to 1200 ° C. for 1 to 5 hours. According to claim 1,
The third step is performed by dissolving the carbon structure and the metal precursor in distilled water at a mass ratio of 2 to 20: 1 and then drying at a temperature of 30 to 100 ° C.
The metal precursor is a precursor of at least one metal selected from the group consisting of molybdenum, tungsten, vanadium, palladium, platinum, rhodium, ruthenium, iridium, manganese, iron, cobalt, and nickel having a structure of a metal salt and a metal oxide. A method for producing a polymeric monomer. According to claim 1,
The fourth step may include preparing phenol by mixing the water-soluble oil and the prepared catalyst and stirring at a rate of 300 to 1000 rpm under a hydrogen pressure of 10 to 50 bar;
Preparing a cyclic hydrocarbon compound by mixing the prepared phenol with a metal catalyst, stirring at a rate of 300 to 1000 rpm under a hydrogen pressure of 3 to 10 bar, and then reacting at 50 to 100 ° C. for 1 to 5 hours; and
A method for producing a polymeric monomer comprising the step of preparing a polymeric monomer using the prepared cyclic hydrocarbon compound and an acid catalyst. According to claim 8,
The method for producing a polymer monomer, characterized in that the water-soluble oil and the prepared catalyst are mixed in a mass ratio of 0.5 to 1.5: 1. According to claim 8,
The method of preparing a polymer monomer comprising at least one selected from the group consisting of caprolactam and adipic acid. According to claim 8,
The acid catalyst is a method for producing a polymer monomer comprising at least one selected from the group consisting of trifluoroacetic acid, nitric acid and boron trifluoride diethyl etherate. According to claim 1,
The water-soluble oil is a method for producing a polymer monomer comprising at least one selected from the group consisting of guaiacol and cresol.

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