KR20190027646A - Catalyst for decomposition reaction of lignin and method for decomposition of lignin using the same - Google Patents

Abstract

Disclosed in the specification are a catalyst for lignin decomposition reaction and a method for lignin decomposition using the same. The catalyst comprises a mixture of a metal-supported catalyst and a metal oxide catalyst and the method uses the catalyst and an alcohol solvent to decompose lignin, a natural phenol polymer, thereby having an effect of manufacturing a phenolic compound and an aliphatic ester compound with a high yield.

Description

TECHNICAL FIELD The present invention relates to a catalyst for decomposing lignin, and a method for decomposing lignin using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

A catalyst for lignin decomposition reaction and a lignin decomposition method using the same are disclosed in this specification.

Recently, the development of technology to produce transportation fuel and polymer precursor using biomass, which is a carbon resource that does not increase carbon dioxide concentration in the atmosphere due to depletion of fossil fuels and the conclusion of the Paris Climate Change Convention, is attracting much attention. In particular, when biomass such as edible crops such as corn and sugarcane is used as a raw material, side effects such as an increase in grain prices will occur. Therefore, research on techniques utilizing non-edible biomass such as waste wood and corn stalks It is actively proceeding.

Edible biomass, which is composed primarily of hexose, is readily converted to useful fuels and compounds such as bioethanol by biological methods. On the other hand, since lignin biomass is composed of cellulose and lignin as a constituent, it is difficult to directly convert the biomass because it has a hard polymer structure. Therefore, it is necessary to break down the polymer structure and convert it to a monomer such as hexane or phenolic compound.

In the case of cellulose, the hydrolysis reaction using an enzyme such as cellulase can be selectively decomposed into hexose due to its regular structure, and the produced hexane sugar is converted into fuel and compound by applying conventional food biofuel technology can do. On the other hand, lignin is a random phenolic polymer and has a very stable and rigid structure, making biologically / chemically efficient degradation very difficult.

Lignin is contained in 15-30 wt% of woody biomass components. If efficient decomposition technology is developed, sustainable carbon resources that can replace petroleum-derived aromatic compounds (benzene, phenol, etc.) . Various lignin decomposition techniques such as hydrolysis, supercritical fluid liquefaction, pyrolysis and hydrocracking have been studied all over the world. However, in order to produce high yield aromatic monomers, a homogeneous base catalyst such as NaOH (Non-Patent Document 1 ) Or an expensive additive such as formic acid (Non-Patent Document 2) must be used in a large amount.

Therefore, it is necessary to develop a low-cost and efficient process technology capable of effectively decomposing the polymer structure of lignin and converting it into an aromatic monomer.

M.J. Hidajat, A. Riaz, J. Park, R. Insyani, D. Verma, J. Kim, Chemical Engineering Journal 317 (2017) 9-19. A. Kloekhorst, Y. Shen, Y. Yie, M. Fang, H.J. Heeres, Biomass and Bioenergy 80 (2015) 147-161.

In one aspect, the present disclosure aims to provide a catalyst for lignin decomposition reaction comprising a mixture of a metal supported catalyst and a metal oxide catalyst.

In another aspect, the present disclosure aims to provide a method of lignin decomposition using the catalyst.

In one aspect, the technique disclosed herein provides a catalyst for lignin decomposition reaction comprising a mixture of a metal supported catalyst and a metal oxide catalyst.

In one exemplary embodiment, the metal-supported catalyst may be one or more metals supported on ruthenium (Ru), palladium (Pd), and nickel (Ni).

In an exemplary embodiment, the metal-supported catalyst may be supported on at least one carrier selected from the group consisting of carbon, silica, alumina, zirconia, and titania.

In one exemplary embodiment, the metal-supported catalyst may be 1 to 10% by weight of the metal supported on the carrier.

In an exemplary embodiment, the metal oxide catalyst may be a mixed metal oxide (Mg-Zr oxide) of magnesium (Mg) and zirconium (Zr).

In an exemplary embodiment, the metal oxide catalyst may be a mixture of magnesium (Mg) and zirconium (Zr) in a weight ratio of 1: 9 to 9: 1.

In an exemplary embodiment, the mixture may comprise a metal supported catalyst and a metal oxide catalyst in a weight ratio of 1: 1 to 1: 3.

In another aspect, the techniques disclosed herein provide a method of lignin degradation comprising the step of performing a lignin degradation reaction using the catalyst.

In an exemplary embodiment, the method may be to perform a lignin degradation reaction by mixing the catalyst with lignin and an alcohol solvent.

In an exemplary embodiment, the lignin degradation reaction may be conducted at 250 to 400 < 0 > C.

In an exemplary embodiment, the lignin degradation reaction time can be from 1 to 8 hours.

In an exemplary embodiment, the method may be to produce a phenolic compound from lignin.

In one aspect, the techniques disclosed herein are effective for providing a catalyst for lignin decomposition reaction that effectively decomposes lignin, including a mixture of a metal-supported catalyst and a metal oxide catalyst. The catalyst has the effect of decomposing lignin to produce a phenolic compound and an aliphatic ester compound at a high yield.

In another aspect, the techniques disclosed herein are effective in providing a lignin decomposition method using the catalyst.

FIG. 1 shows the results of the lignin decomposition reaction according to the type of catalyst in one experimental example of the present specification.
FIG. 2 shows the results of lignin decomposition reaction according to the composition of the metal oxide catalyst in one experimental example of the present invention.
Figure 3 shows the distribution of aromatic compounds produced in various experimental conditions of the present invention under various catalytic conditions.
4 shows the results of the lignin decomposition reaction according to the reaction temperature in one experimental example of the present specification.
5 shows the results of the lignin decomposition reaction according to the hydrogen gas injection in the experimental example of the present specification.
6 shows the results of the lignin degradation reaction according to the reaction time in one experimental example of the present specification.

Hereinafter, the present invention will be described in detail.

In one aspect, the technique disclosed herein provides a catalyst for lignin decomposition reaction comprising a mixture of a metal supported catalyst and a metal oxide catalyst.

In one exemplary embodiment, the metal-supported catalyst may be one or more metals supported on ruthenium (Ru), palladium (Pd), and nickel (Ni). Preferably, the ruthenium (Ru) metal may be suitable for the production of aromatic monomers by promoting hydrogenolysis of lignin.

In one exemplary embodiment, the metal-supported catalyst means a catalyst in which a metal is supported on a support. It may be preferable that the metal is supported on a support having a large surface area for increasing the degree of dispersion of the metal. In this respect, it is preferable that the metal-supported catalyst has a metal supported on a support having a specific surface area of 80 to 1,000 m ² / g. In another exemplary embodiment, the metal-supported catalyst has a specific surface area of at least 80 m ² / g, at least 100 m ² / g, at least 120 m ² / g, at least 140 m ² / g, at least 160 m ² / ² / g or more, 200 m ² / g or more, 250 m ² / g or more, 300 m ² / g or more, 350 m ² / g, yet more or 400 m ² / g more than 1,000 m ² / g or less, 900 m ² / g or less, 800 m ² / g or less, 700 m ² / g or less, or 600 m ² / g or less.

In an exemplary embodiment, the carrier may be one or more selected from the group consisting of carbon, silica, alumina, zirconia, and titania.

In an exemplary embodiment, the metal supported catalyst may be suitable for producing aromatic monomers by promoting hydrocracking of lignin on a carbon carrier.

In one exemplary embodiment, the metal-supported catalyst may be 1 to 10% by weight of the metal supported on the carrier. In another exemplary embodiment, the metal-supported catalyst may comprise at least 1 wt%, at least 2 wt%, at least 3 wt%, at least 4 wt%, at least 5 wt%, at least 6 wt%, or at least 7 wt% , Not more than 10 wt%, not more than 9 wt%, not more than 8 wt%, not more than 7 wt%, not more than 6 wt%, not more than 5 wt%, not more than 4 wt% or not more than 3 wt% . Accordingly, it is possible to prevent the problem that the content of the supported metal is small and the catalytic reactivity, which is measured by the conversion and yield, may be too low, and the problem that the content of the supported metal is high and the catalyst production cost may be increased may be prevented.

In an exemplary embodiment, the metal oxide catalyst may be a mixed metal oxide of magnesium (Mg) and zirconium (Zr). The base point of the mixed metal oxide catalyst has an effect of enhancing the lignin decomposition efficiency through solvolysis reaction. In addition, there is an effect of increasing the alkylated phenol yield by promoting the alkylation reaction between the primary generated phenolic monomers and the alcohol solvent.

In one exemplary embodiment, the metal oxide catalyst comprises magnesium (Mg) and zirconium (Zr) in a weight ratio of 1: 9 to 9: 1, a weight ratio of 1: 7 to 7: 1: 3 to 3: 1, preferably 1: 1 to 3: 1, in the weight ratio of 1: 4 to 4: 1, thereby improving the lignin decomposition reaction efficiency.

In an exemplary embodiment, the mixture can increase the lignin decomposition reaction efficiency by including the metal supported catalyst and the metal oxide catalyst in a weight ratio of 1: 1 to 1: 3, or 1: 1 to 1: 2.

In another aspect, the techniques disclosed herein provide a method of lignin degradation comprising the step of performing a lignin degradation reaction using the catalyst.

In an exemplary embodiment, the lignin decomposition reaction may proceed on a hybrid catalyst in which the metal supported catalyst and the metal oxide catalyst are physically mixed. By using the mixed catalyst in this way, the base point of the metal oxide catalyst and the active site for promoting the hydrogenation reaction of the metal-supported catalyst synergize with each other, thereby remarkably increasing the decomposition efficiency of lignin into an aromatic monomer.

In an exemplary embodiment, the lignin may be derived from woody biomass.

In an exemplary embodiment, the lignin may be separated from or produced from the biomass.

In an exemplary embodiment, the method may be to perform a lignin degradation reaction by mixing the catalyst with lignin and an alcohol solvent. The alcohol solvent acts as a nucleophile for the lignin solvolysis and as a hydrogen donor for hydrogenolysis of lignin, thus enhancing the efficiency of lignin degradation.

In an exemplary embodiment, the alcohol solvent may be one or more selected from the group consisting of methanol, ethanol and isopropanol.

In an exemplary embodiment, the lignin decomposition reaction may be carried out at 250 to 400 占 폚, 300 to 400 占 폚, preferably 300 to 350 占 폚. Accordingly, it is possible to prevent the problem that the reaction temperature is low and the lignin decomposition reaction activity to be lowered, and to prevent the problem that the reaction temperature is high and the alcohol solvent is decomposed and lost so much that the process cost is increased.

In an exemplary embodiment, the lignin degradation reaction time can be from 1 to 8 hours.

In an exemplary embodiment, the method may be to produce a phenolic compound and an aliphatic ester compound from lignin.

In an exemplary embodiment, the phenolic compound is selected from the group consisting of guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-propylguaiacol, 4-propylguaiacol, syringol, 4-methyl syringol, 2-methoxyphenylethanol, Eugenol, acetovanillone, May be at least one selected from the group consisting of guaiacylacetone, homovanillic acid, homovanillic alcohol, ethyl vanillate and dihydroconiferyl alcohol.

In an exemplary embodiment, the aliphatic ester compound is selected from the group consisting of hexadecanoic acid ethyl ester, heptadecanoic acid ethyl ester, and octadecanoic acid ethyl ester. ≪ / RTI > These fatty acid compounds are derived from the triglyceride impurities contained in lignin and can be converted into esters by reaction with an alcohol solvent.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Example  1. Metal supported catalyst and metal oxide catalyst production

Ruthenium (Ru / C) and palladium (Pd / C) catalysts supported on activated carbon among metal supported catalysts were purchased from Sigma Aldrich. The content of ruthenium and palladium in the catalyst was 5 wt% each. The nickel (Ni / C) catalyst supported on activated carbon was prepared by impregnating the dried activated carbon with an aqueous solution of nickel (II) nitrate hexahydrate, Ni (NO ₃ ) ₂ · 6H ₂ O) . The amount of nickel metal supported was 10% by weight with respect to the carbon carrier. All the catalysts were dried in an oven at 120 ° C for 4 hours, then reduced again in a hydrogen stream at 300 ° C for 3 hours, and then used in the reaction.

The metal oxide catalyst, MgO / ZrO _2, was prepared by coprecipitation. First, an aqueous solution of zirconium oxynitrate hydrate (ZrO (NO ₃ ) ₂ · 2H ₂ O) and magnesium nitrate hexahydrate (Mg (NO ₃ ) ₂ · 6H ₂ O) was prepared. drop / s < / RTI > An aqueous ammonia solution was also added simultaneously to keep the pH constant during the addition. After the addition was completed, the final mixed solution was aged at 4O < 0 > C for 4 hours and then filtered to separate the solid precipitate. The separated solid precipitate was washed with distilled water, dried, and calcined at 600 ° C for 3 hours in a nitrogen stream, and then used for the catalytic reaction. Three different MgO / ZrO ₂ catalysts with different Mg / Zr ratios of 0.11, 1 and 3 were prepared by varying the amounts of Mg and Zr metal precursors and used in the following experiments.

Comparative Example  One. MgO  And Mg-Al oxide metal oxide catalysts

Single-metal oxide MgO catalysts without Zr were purchased from Sigma-Aldrich. The mixed metal oxide Mg-Al oxide catalyst was prepared by coprecipitation using aluminum nitrate nonahydrate (Al (NO ₃ ) ₃ .2H ₂ O) precursor in the same manner as in Example 1. The composition of the catalyst was adjusted so that the ratio of Mg / Al was 3.

Example  2. From biomass  Lignin extraction

Lignin samples for catalysis were prepared directly from pine sawdust via an organosolv process. First, 1 kg of pine sawdust, 5 liters of water / ethanol (35/65 vol.%) Mixture, and 4 mL of sulfuric acid were added to a batch reactor of 10 L capacity. Then, the sawdust was dissolved in the aqueous ethanol solution for 1 hour Lt; / RTI > After the reactor was sealed well, the temperature was raised to 170 DEG C and lignin extraction reaction was performed for 3 hours. After completion of the reaction, the reactor was cooled to 40 DEG C or lower by using a fan, and the reaction suspension was filtered to obtain lignin dissolved in an aqueous ethanol solution. A large amount of low temperature water was added to the recovered lignin / ethanol / water mixture to precipitate lignin. The precipitated lignin was recovered by filtration and dried to be used for the catalytic reaction.

Experimental Example  1. Lignin decomposition experiment

Catalytic cracking of lignin was carried out in a high pressure batch reactor equipped with a stirrer of 160 ml capacity. After 0.2 g of the metal supported catalyst prepared in Example 1 and 0.3 g of MgO / ZrO ₂ , or a physical mixture (0.5 g) of the two catalysts were injected into the reactor, 40 mL of ethanol as a solvent and lignin 1 g was added thereto. Then, the nitrogen gas was filled to 10 bar and the impeller attached to the reactor was operated at 500 rpm, and the reaction temperature was increased to 350 ° C while stirring. After reaching the reaction temperature, the reaction was maintained for 1 hour, then the catalyst and solid residues were filtered out with a filter, and only the liquid product was obtained. The qualitative and quantitative analysis of aromatic monomers and aliphatic ester compounds contained in the liquid product was performed using GC-MS and GC-FID. The yields of aromatic monomers and aliphatic ester compounds were calculated as the weight of each compound produced relative to the weight of the lignin added. The results of the above experiment are shown in Figs.

Referring to FIG. 1, the yields of aromatic monomers and aliphatic ester compounds are remarkably high when a physical mixture of two catalysts is used as compared with the case where Ru / C or MgO / ZrO ₂ is used as a single catalyst. In particular, in the case of MgO / ZrO ₂ single catalyst, the yield of aromatic monomers is similar to that obtained in the case of the reaction in the non-catalytic condition, and the catalytic effect thereof is very small when used singly, while the yield of aromatic monomers is remarkably increased when the mixed catalyst is used. It was found that a synergistic effect occurred in decomposition.

As a comparative example, a catalyst reaction result obtained by mixing a single metal oxide MgO catalyst not containing Zr and a Mg-Al oxide catalyst containing Al as a mixed metal oxide with Ru / C is also shown in FIG. Both catalysts showed significantly lower aromatic monomer yield than MgO / ZrO ₂ mixed with the metal-supported catalyst, and showed lower yields of aromatic monomers than with Ru / C monocatalysts (see Table 2 below).

FIG. 2 shows that the composition of the MgO / ZrO ₂ catalyst greatly affects the lignin decomposition efficiency in the lignin decomposition reaction using the mixed catalyst. As the weight ratio of Mg / Zr increased from 0.11 to 3, the yields of aromatic monomers and aliphatic ester compounds also increased from 15.5% to 22%.

Figure 3 shows the distribution of aromatic monomers produced at various catalyst conditions. When Ru / C and MgO / ZrO ₂ hybrid catalysts are used, 4-ethylguaiacol, 4-propylguaiacol, 4-methyl syringol, 2- The yield of phenolic monomers added with an alkyl group such as 2-methoxyphenylethanol increased sharply.

Experimental Example 2 Effect of metal-supported catalyst in lignin decomposition

Ruthenium (Ru / C), palladium (Pd / C), and nickel (Ni / C) catalysts supported on activated carbon were used as metal supporting catalysts in the same manner as in Experimental Example 1. The lignin decomposition reaction was carried out at a reaction temperature of 350 ° C. using a physical mixture (0.5 g) of the metal supported catalyst (0.2 g) and MgO / ZrO ₂ (0.3 g) catalyst as catalysts. The experimental results are shown in Table 1 .

According to Table 1, it was found that ruthenium (Ru / C) catalyst supported on activated carbon among various metal supported catalysts produced the highest yield (18.28 wt%) of phenolic compounds when used with MgO / ZrO ₂ catalyst . The yield of aliphatic ester compounds was also highest when Ru / C catalyst was used.

Entry catalyst Product yield (wt%) Phenolic compound Aliphatic ester Total compound One Ru / C + MgO / ZrO ₂ 18.28 2.85 21.12 2 Pd / C + MgO / ZrO ₂ 10.27 2.63 12.90 3 Ni / C + MgO / ZrO ₂ 7.16 1.01 8.17

Experimental Example  3. Effect of metal oxide catalysts on lignin degradation

A lignin decomposition reaction was carried out in the same manner as in Experimental Example 1, except that a single metal oxide MgO or Al-containing Mg-Al oxide not containing Zr was used as a metal oxide catalyst. The lignin decomposition reaction was carried out at a reaction temperature of 350 ° C. using a physical mixture (0.5 g) of the metal oxide catalyst (0.3 g) and Ru / C (0.2 g) as a catalyst.

According to Table 2, when the MgO / ZrO ₂ catalyst containing Mg and Zr is used as a catalyst together with Ru / C, the yield of aromatic monomers is remarkably increased compared to the Ru / C single catalyst, but MgO or Mg- When Al oxide was used, the yield of aromatic monomers was lower than that of Ru / C single catalyst, and no synergistic effect was observed.

Entry catalyst Product yield (wt%) Phenolic compound Aliphatic ester Total compound One Ru / C (0.2 g) 10.89 1.17 12.06 2 Ru / C + MgO / ZrO ₂ 18.28 2.85 21.12 3 Ru / C + MgO 7.36 0.62 7.98 4 Ru / C + Mg-Al oxide 8.37 0.57 8.94

Experimental Example 4 Effect of Reaction Temperature on Lignin Degradation

A lignin decomposition reaction was carried out in the same manner as in Experimental Example 1 using a mixture of Ru / C catalyst (0.2 g) and MgO / ZrO ₂ catalyst (0.3 g) having a Mg / Zr ratio of 3, Respectively. The results of the experiment are shown in FIG.

FIG. 4 shows that the yield of aromatic monomers and aliphatic ester compounds was remarkably high at 350 ° C., compared with the lignin decomposition reaction performed at 250 to 300 ° C.

Experimental Example 5 Influence of hydrogen gas injection in lignin decomposition reaction

A lignin decomposition reaction was carried out in the same manner as in Experimental Example 1 using a mixture of Ru / C catalyst (0.2 g) and MgO / ZrO ₂ catalyst (0.3 g) having a Mg / Zr ratio of 3, And the reaction was carried out. The results of the experiment are shown in FIG.

5, when the hydrogen gas is used instead of the nitrogen gas, the yield of the aromatic monomer and the aliphatic ester compound increases to some extent, but the change is not large. Since the ethanol acts as a hydrogen donor for lignin hydrogenolysis during the reaction, the effect of additional hydrogen gas injection on the reaction is considered to be insignificant.

Experimental Example 6 Effect of Reaction Time on Lignin Degradation

A lignin decomposition reaction was carried out in the same manner as in Experimental Example 1 using a mixture of Ru / C catalyst (0.2 g) and MgO / ZrO ₂ catalyst (0.3 g) having a Mg / Zr ratio of 3, Respectively. The results of the experiment are shown in Fig.

As can be seen from FIG. 6, as the reaction time increases from 1 hour to 4 hours, the yields of aromatic monomers and aliphatic ester compounds also increase continuously. After a final reaction time of 4 hours, the yield of aromatic monomers and aliphatic ester compounds increased to 36%.

Having described specific portions of the present invention in detail, it will be apparent to those skilled in the art that this specific description is only a preferred embodiment and that the scope of the present invention is not limited thereby. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (12)

A catalyst for lignin decomposition reaction comprising a mixture of a metal supported catalyst and a metal oxide catalyst.
The method according to claim 1,
Wherein the metal-supported catalyst is one in which at least one metal selected from the group consisting of ruthenium (Ru), palladium (Pd), and nickel (Ni) is supported.
The method according to claim 1,
Wherein the metal-supported catalyst is supported on at least one carrier selected from the group consisting of carbon, silica, alumina, zirconia, and titania.
The method according to claim 1,
Wherein the metal supported catalyst comprises 1 to 10% by weight of a metal supported on the basis of the weight of the carrier.
The method according to claim 1,
Wherein the metal oxide catalyst is a mixed metal oxide of magnesium (Mg) and zirconium (Zr).
6. The method of claim 5,
Wherein the metal oxide catalyst is a mixture of magnesium (Mg) and zirconium (Zr) in a weight ratio of 1: 9 to 9: 1.
The method according to claim 1,
Wherein the mixture comprises a metal supported catalyst and a metal oxide catalyst in a weight ratio of 1: 1 to 1: 3.
A lignin decomposition method comprising performing a lignin decomposition reaction using a catalyst according to any one of claims 1 to 7.
9. The method of claim 8,
Wherein the lignin decomposition reaction is carried out by mixing lignin and an alcohol solvent in the catalyst.
9. The method of claim 8,
Wherein the lignin decomposition reaction is carried out at 250 to 400 캜.
9. The method of claim 8,
Wherein the lignin decomposition reaction time is 1 to 8 hours.
9. The method of claim 8,
Wherein the method comprises preparing a phenolic compound from lignin.

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