KR101298688B1 - Novel metal catalyst supported on activated carbon aerogel bearing cation-exchanged heteropolyacid and decomposition method of lignin compounds using said catalyst - Google Patents

Abstract

PURPOSE: A precious metal catalyst being immersed in activated carbon aerogel including cation exchange heteropoly acid and a decomposition method of lignin compound by using the same are provided to replace the conventional lignin pyrolysis method carried out under the existing condition of high temperature and high pressure (400°C, 50 atmosphere). CONSTITUTION: A precious metal catalyst being immersed in activated carbon aerogel including cation exchange heteropoly acid selectively disassembles a carbon-oxygen-carbon bond of an inner bond of lignin compound to produce an aromatic compound and is indicated as the chemical formula: M/Q_xH_3.0-xPW_12O_40/ACA. The precious metal catalyst is manufactured by: exchanging a hydrogen ion with one or more cation selected from alkaline metal ions or ammonium ions to produce heteropoly acid; immersing the heteropoly acid within the range of 5-70 weight% based on weight% of activation carbon aerogel to form activation carbon aerogel with an acid center; and immersing at least one precious metal selected from a group consisting of palladium, rhodium, and ruthenium and platinum in the activation carbon aerogel with the acid center within the range of 1-30 weight% based on weight% of activation carbon aerogel. A decomposition method of lignin compound by using the same comprises a step of decomposing lignin composition to produce an aromatic compound under the existence of the precious metal catalyst being immersed in activated carbon aerogel including cation exchange heteropoly acid, at 300°C or lower and 50 hydrogen atmosphere or lower. [Reference numerals] (AA) 4-phenoxyphenol conversion rate; (BB) Selectivity rate of main product; (CC) Yield rate of main product

Description

NOVEL METAL CATALYST SUPPORTED ON ACTIVATED CARBON AEROGEL BEARING CATION-EXCHANGED HETEROPOLYACID AND DECOMPOSITION METHOD OF LIGNIN COMPOUNDS USING SAID CATA

The present invention relates to a noble metal catalyst supported on an activated carbon aerogel including a cation-substituted heteropolyacid and a method for decomposing a lignin compound using the catalyst, and more particularly, by selectively decomposing a carbon-oxygen-carbon bond in an internal bond of a lignin compound. Used to prepare aromatic compounds, the formula M / Q _x H _3.0-x PW ₁₂ O ₄₀ / ACA (M is a noble metal, Q _x H _3.0-x PW ₁₂ O ₄₀ is a cation-substituted heteropolyacid, Q is an alkali metal Cation-substituted heteropolyacids represented by one or more cations selected from ions or ammonium ions, 0 ≦ x ≦ 3, ACA is an activated carbon aerogel) and hydrogen ions substituted with one or more cations selected from alkali metal ions or ammonium ions Activated carbon air having a acidic point formed by loading in the range of 5 to 70% by weight based on the weight of the activated carbon airgel Activated carbon aerogels including cation-substituted heteropolyacids, characterized in that the gel is supported with one or more precious metal catalysts selected from the group consisting of palladium, rhodium, ruthenium and platinum in the range of 1 to 30% by weight, based on the weight of the activated carbon aerogel. The present invention relates to a noble metal catalyst supported on and a method for decomposing lignin compounds using the catalyst.

The chemical industry, based on fossil fuels such as coal and oil, is changing its paradigm to biomass-based chemical industry due to the problem of rising prices due to depletion of fossil fuels and global warming caused by pollution in the air. The biomass-based chemical industry is attracting attention as an energy source that does not contribute to global warming because the cycle of carbon dioxide generated after use occurs over several months or years. However, biomass, such as starch and sugars, is an energy source, but at the same time plays an important role as a food resource. On the other hand, woody biomass is attracting attention as a material that does not compete with existing food resources. The woody biomass is composed of cellulose, hemicellulose and lignin. Cellulose and hemicellulose can be converted into high-value energy sources such as biodiesel and bioethanol by using a post-treatment process. Lignin is used as a low value fuel for combustion in power production or for power generation. However, since a large amount of aromatic material is contained in lignin, a technique of using aromatics generated by decomposing lignin as a chemical substance or a fuel additive is attracting attention.

Although lignin classified by the production method shows a difference in molecular weight and molecular weight distribution, as shown in FIG. 1, since aromatic substances such as benzene and phenol are polymers polymerized by carbon-carbon (CC) bond and carbon-oxygen (CO) bond, It is a chemically very stable substance. Therefore, it is difficult to produce monomeric aromatic chemicals by decomposing and converting lignin, and the materials produced through the above process are less competitive than those produced by conventional petroleum refining. However, with the recent rise in oil prices, aromatic materials produced by decomposing lignin are expected to be competitive, and research and development on lignin decomposition are actively underway.

Lignin is a polymer material in which koniphenyl alcohol, cumeryl alcohol, and cinafil alcohols are polymerized by enzymes. Therefore, lignin decomposition studies mainly use model compounds that can easily express lignin structure. Lignin model compounds include beta carbon-oxygen-4 carbon (β-O-4) bonds, alpha carbon-oxygen-4 carbon (α-O-4) bonds, beta carbon-5 carbon (β-5) bonds, and 4 Compounds capable of expressing carbon-oxygen-5 carbon (4-O-5) bonds are mainly used ( Biomass and Bioenergy, 2009, 33, 1122-1130 ). Phenyl ether is mainly used to express the highest ratio of beta carbon-oxygen-carbon bonds among lignin model compounds, and to express 4-O-5 bonds showing the highest binding energy among CO bonds in lignin. 4-phenoxyphenol shown in 2 is mainly used as a lignin model compound.

Pyrolysis method to directly decompose lignin produces aromatic substance by decomposing lignin at high pressure and high temperature. The conversion rate is about 20% or more under the reaction conditions of 450 ° C. and 100 atm, and the reaction temperature and pressure are below 450 ° C. and 100 atm. In this case, the conversion is less than 10% ( J. Org. Chem., 1995, 60, 6523-6536). However, pyrolysis has a problem in that the yield is low while decomposing lignin at high temperature and high pressure. Recently, lignin high value-added technology using a catalyst has attracted attention. The Lignol process developed by Hydrocarbon Research, Inc. (HRI) yielded an aromatic yield of at least about 30% using iron, cobalt, molybdenum and nickel in the form of oxides supported on alumina and silica as catalysts (US Pat. No. 4,647,704 / 1987). Hydrolysis of lignin using a zeolite catalyst such as H-ZSM-5 is a carbon-to-carbon (CC) bond that has a relatively strong bond with a carbon-oxygen (CO) bond that has a relatively weak bond inside the lignin. Decompose selectively. Catalytic performance in lignin decomposition with zeolites is strongly influenced by the structure and acidity of the zeolites ( Bioresource Tech., 1993, 45, 189-194 ).

As a method of selectively decomposing carbon-oxygen (CO) bonds of lignin, a technique of decomposing lignin using a cation-substituted heteropolyacid was introduced. Decomposition of the lignin model compound with a cesium ion-substituted heteropolyacid (Cs _2.5 H _0.5 PW ₁₂ O ₄₀ ) catalyst showed excellent lignin decomposition efficiency with conversion and main product yields of 80% and 60%, respectively. This method is useful for decomposing lignin, since the carbon-oxygen bond is distributed about 60 to 70% inside lignin ( Catal. Comm., 2010, 12, 1-4) (Korean Patent Application No. 10-2010). -0030562 (2010)). Precious metals supported on cesium ion-substituted heteropolyacids have the effect of increasing the adsorption capacity on the surface of the acid-catalyzed carbon-oxygen (CO) bond of lignin to increase the conversion and yield ( Korean J. Chem. Eng., 2010, 28 1177 -1180, Republic of Korea Patent Application 10-2010-0066173 (2010)).

Precious metal catalysts supported on activated carbon are also effective for the degradation of lignin or lignin oligomers ( Chem. Sus. Chem., 2008, 1, 626-629 ). However, activated carbon is inefficient in breaking down lignin, which has a large molecular size, because pores are distributed mainly between 1-3 nm. Carbon airgel is a carbon compound in which medium pores are developed, and the pores are distributed between 3-20 nm according to the preparation method thereof. Therefore, high conversion and yield can be obtained by decomposing lignin using a palladium catalyst supported on activated carbon aerogels in which medium pore-developed carbon aerogels are activated with phosphoric acid (Korean Patent Application 10-2011-0010158 (2011)). However, cesium ion-substituted heteropolyacid catalysts and noble metal catalysts supported on activated carbon aerogels are not effective in decomposing 4-phenoxyphenol, a model compound of 4-O-5 bond, which has the highest binding energy among lignin model compounds.

Treatment of sulfuric acid with activated carbon or various carbon materials by wet and dry methods introduces acid points into the carbon chain and is used primarily as a solid acid catalyst. By using carbon as a solid acid carbon material catalyst and catalyst carrier prepared by acid treatment, problems such as catalyst recovery, separation from reactants, and reactor corrosion generated when using a liquid catalyst can be solved. In addition, acid-treated activated carbon or carbon may be used as an effective carrier for supporting precious metals by utilizing carbon porosity and structural stability ( Nature, 2005, 438, 178 ).

U.S. Patent 4,647,704 (D.J. Engel, K.Z.Steigleder) 1987. Republic of Korea Patent Application 10-2010-0030562 (Song In-gyu, Park Hae-woong, Park Sun-young) 2010. Republic of Korea Patent Application 10-2010-0066173 (Song In-gyu, Park Hae-woong, Park Sun-young) 2010. Republic of Korea Patent Application 10-2011-0010158 (Song In-gyu, Park Hae-woong, Hong Ung-ki, Lee Yun-jae) 2011.

J.B. Binder, M.J. Gray, J.F. White, Z. C. Zhang, J.E. Holladay, Biomass and Bioenergy Vol. 33, p. 1122 (2009). P.F. Britt, A.C. Buchanan, E. A. Malcolm, J. Org. Chem. 60, p. 6523 (1995). A. Oasmaa, R. Alen, Bioresource Tech. 45, pp. 189 (1993). H.W. Park, S. Park, D. R. Park, J. H. Choi, I.K. Song, Catal. Commun. 12 Volume 1 (2010). H.W. Park, S. Park, D. R. Park, J. H. Choi, I.K. Song, Korean J. Chem. Eng. 28, 1177 (2010). N. Yan, C. Zhao, P.J. Dyson, C. Wang, L.-T. Liu, Y. Kou, Chem. Shut up. Chem. Vol. 1, p. 626 (2008).  M Toda, A. Takagaki, M. Okamura, J.N. Kondo, S. Hayashi, K. Domen, M. Hara, Nature 438 pp. 178 (2005).

Accordingly, the technical problem to be achieved by the present invention is to solve the above-mentioned problems and selectively decompose the carbon-oxygen-carbon bond among the lignin internal bonds, more specifically, 4- showing the highest binding energy among the carbon-oxygen-carbon bonds. To provide catalytic design and catalytic process development that effectively breaks O-5 bonds.

In order to achieve the above technical problem, the present invention is used to prepare an aromatic compound by selectively decomposing the carbon-oxygen-carbon bond among the internal bonds of the lignin compound, the formula M / Q _x H _3.0-x PW ₁₂ O ₄₀ / ACA (M is a noble metal, Q _x H _3.0-x PW ₁₂ O ₄₀ is a cation substituted heteropolyacid, Q is at least one cation selected from alkali metal ions or ammonium ions, 0≤x≤3, ACA is activated carbon Aerogel), wherein the hydrogen ions are supported by a cation-substituted heteropolyacid substituted with at least one cation selected from alkali metal ions or ammonium ions in the range of 5 to 70% by weight based on the weight of the activated carbon airgel to form an acid point. The weight of the activated carbon aerogel is added to the activated carbon aerogel by at least one precious metal catalyst selected from the group consisting of palladium, rhodium, ruthenium and platinum. It provides a noble metal catalyst supported on an activated carbon aerogel containing a cationic substituted heteropoly acid, characterized in that supported on the basis of 1 to 30% by weight.

In addition, the present invention is a carbon airgel produced by polymerizing the resorcinol and formaldehyde (R / F ratio) of the resorcinol and formaldehyde in the range of 0.1 ~ 2.0 One or more activators selected from the group consisting of potassium hydroxide, phosphoric acid, and zinc chloride, supported on activated carbon aerogels containing cation-substituted heteropolyacids, which are activated in a temperature range of 200 to 800 ° C., for 1 to 3 hours, and in a nitrogen atmosphere. Precious metal catalysts.

In addition, the present invention decomposes the lignin compound in the presence of a noble metal catalyst supported on the activated carbon aerogel including the cation-substituted heteropolyacid at a temperature of less than 300 ℃ and a pressure of 50 atm or less hydrogen to produce an aromatic compound Provided are methods for compound decomposition.

Decomposition reaction of lignin model compound using a noble metal catalyst supported on activated carbon aerosol containing acid point by treating cationic substituted heteropolyacid of the present invention can replace the lignin pyrolysis method performed at the existing high temperature and high pressure condition (400 ℃, 50 atm). It provides a technology that can produce aromatics such as benzene and phenol by selectively decomposing carbon-oxygen-carbon bonds among the internal bonds of lignin at relatively low temperature and low pressure (200 ° C., 10 atm).

1 is a lignin structural diagram illustrating lignin internal binding
FIG. 2 is a schematic diagram of a lignin model compound having a 4-carbon-oxygen-5-carbon (4-O-5)
3 is a process for preparing an activated carbon airgel formed by treating a cation-substituted heteropolyacid according to Preparation Example 1 and forming an acid point and a process for preparing a palladium catalyst supported on an activated carbon airgel having an acid point;
4 is a palladium catalyst (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40) supported on an activated carbon airgel formed by treating a cationic substituted heteropolyacid produced in Preparation Example 1 And 50% by weight) nitrogen adsorption and desorption curve
5 is a palladium catalyst (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40 supported on an activated carbon airgel formed by treating a cationic substituted heteropolyacid produced in Preparation Example 1 And 50% by weight of XRD pattern
6 is a palladium catalyst (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40) supported on an activated carbon airgel formed by treating a cationic substituted heteropolyacid produced in Preparation Example 1 And a TEM image of the palladium particle size distribution and pore shape of 50% by weight).
7 is a palladium catalyst (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40 supported on an activated carbon airgel formed by treating a cationic substituted heteropolyacid produced in Preparation Example 1 And 4-phenoxyphenol decomposition reaction performance using 50% by weight)
8 is a palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on activated carbon aerogels containing cationic substituted heteropolyacids produced in Preparation Example 1 and Comparative Preparation Examples 1 and 2, and supported on activated carbon aerogels. Comparison of 4-phenoxyphenol Degradation Performance of Palladium Catalyst (Pd / ACA) and Palladium Catalyst (Pd / AC) Supported on Commercial Activated Carbon

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The noble metal catalyst supported on the activated carbon aerogel including the cation-substituted heteropolyacid of the present invention is used to prepare an aromatic compound by selectively decomposing the carbon-oxygen-carbon bond among the internal bonds of the lignin compound, and the formula M / Q _x H _{3.0- x} PW ₁₂ O ₄₀ / ACA (M is a noble metal, Q _x H _3.0-x PW ₁₂ O ₄₀ is a cationic substituted heteropolyacid, Q is at least one cation selected from alkali metal ions or ammonium ions, 0≤x≤3 ACA is an activated carbon aerogel), and the cation-substituted heteropolyacid in which hydrogen ions are substituted with at least one cation selected from alkali metal ions or ammonium ions is in the range of 5 to 70% by weight based on the weight of the activated carbon aerogel. At least one member selected from the group consisting of palladium, rhodium, ruthenium and platinum on an activated carbon airgel which is supported and forms an acid point The noble metal catalyst is characterized in that it is supported in the range of 1 to 30% by weight based on the weight of the activated carbon airgel.

The noble metal catalyst supported on the activated carbon aerogel containing the acid point for decomposition of the lignin model compound of the present invention is (a) RF after polymerization of resocinol and formaldehyde using sodium hydrogen carbonate as a catalyst. Producing (Resocinol-Formaldehyde) gel; (b) exchanging the RF gel prepared in the step (a) with acetone and drying; (c) carbonizing the RF gel produced in the step (b) to produce carbon aerogels; (d) pre-treating the carbon aerogels produced in the step (c) with potassium hydroxide, phosphoric acid and zinc chloride to produce active carbon aerogels; (e) washing the activated carbon aerogels produced in the step (d) with water, followed by drying; (f) treating the cation-substituted heteropolyacid to add an acid point to the activated carbon aerogel produced in step (e); (g) treating the cation-substituted heteropolyacid produced in step (e) to carry an noble metal in an activated carbon airgel containing an acid point and then firing to produce an activated carbon airgel in which the precious metal oxide is supported; (h) Reducing the precious metal oxide supported on the activated carbon airgel containing acid point produced in step (g) to hydrogen to reduce the precious metal catalyst supported on the activated carbon airgel containing acid point (M / Q _x H _3.0-x PW ₁₂ O ₄₀ / ACA).

The ratio (R / F ratio) of resorcinol to formaldehyde used in step (a) is between 0.1 and 2.0, and they are sufficiently dissolved in distilled water and mixed. Also, sodium bicarbonate is added as a catalyst to the mixed solution of resorcinol and formaldehyde to initiate the polymerization reaction, and the amount of sodium hydrogencarbonate added is preferably 1/50 to 500 in terms of resorcinol. In the polymerization using the catalyst, the polymerization reaction time is preferably from 1 to 3 hours, and after the initiation of polymerization, the polymerization reaction is maintained at 80 to 120 ° C for 12 to 24 hours to sufficiently form an RF gel.

In step (b), the water contained in the RF gel prepared in step (a) is exchanged with acetone. After the RF gel containing water is thoroughly washed with a high purity acetone solution at 50 ° C, Dry for 3 to 5 hours to produce RF gel.

In step (c), the RF gel produced in step (b) is carbonized to produce carbon aerogels. The carbon gelation conditions of the RF gel include a temperature range of 200 to 800 ° C., a nitrogen atmosphere, and a carbonization do.

In step (d), the step of activating the carbon airgel produced in step (c) may be a step of activating carbon aerogels selected from potassium hydroxide (KOH), phosphoric acid (H ₃ PO ₄ ) and zinc chloride (ZnCl ₂ ) Mix by impregnation method. The carbon aerogels mixed with the activating material are sufficiently activated at a temperature of 200 to 800 ° C for 1 to 3 hours in a nitrogen atmosphere. The ratio of the activating material to the carbon airgel is between 0.5 and 5 by weight, preferably between 1 and 2. This is because the carbon airgel is not activated when the amount of the activating substance is out of the range of 0.5 or less, and when it is 5 or more, the structure of the carbon airgel is decayed and catalyst activity is lowered.

In step (e), the activated carbon aerogels containing the active material produced in step (d) are washed with water, and the acid material remaining on the activated carbon aerogels is thoroughly washed using distilled water. When the pH of the washing water is between 6.5 and 7.0, it is judged that the active substance is sufficiently washed. The washed activated carbon aerogels are dried at 110 ° C for 5 hours.

Step (f) is a step of treating a cationic substituted heteropoly acid to include an acid point in the activated carbon airgel produced in step (e), the heteropoly acid is impregnated in an activated carbon aerogel and dried at 80 ° C. for 3 hours. . Activated carbon aerogels, including dried heteropolyacids, are substituted for selected cations. Substituted cationic Q species is one selected from alkali metal or ammonium ions in aqueous solution, and the cationic material in aqueous solution is mechanically mixed into the activated carbon aerogel carrying heteropoly acid. Activated carbon aerogels containing cation-substituted heteropolyacids are dried at 110 ° C for 5 hours and then calcined at 250 to 300 ° C for 2 to 5 hours to be used as noble metal catalyst carriers. The supported amount of the cation-substituted heteropolyacid is preferably in the range of 1 to 70% by weight, and more preferably in the range of 10 to 30% by weight, based on the activated carbon aerogel. If the supported amount of the cation-substituted heteropolyacid is less than 10%, the acid activity contained in the activated carbon aerogel is weak and the catalytic activity is lowered. At 70% or more, the acid activity is weakened due to the agglomeration of the cation-substituted heteropolyacid, thereby lowering the catalytic activity. .

In step (g), the precious metal material is calcined after supporting the activated carbon airgel acid-treated with the cation-substituted heteropolyacid produced in step (f), followed by calcination, and the available precious metal M is composed of palladium, platinum, rhodium and ruthenium. It is one or more selected from the group, and the noble metal precursor is completely dissolved in a solvent and then supported on the activated carbon airgel by impregnation. Activated carbon aerogels mixed with precious metal precursors are thoroughly dried at 80 ° C for 5 hours and then calcined at a temperature ranging from 250 to 350 ° C for 2 to 5 hours in an air atmosphere. As a result, the noble metal oxide is supported on the activated carbon aerogels containing the acid sites. When the calcination temperature is 250 ° C or less, the calcination is incomplete, and when the temperature is 350 ° C or more, sintering of the noble metal particles may occur. The proportion of the noble metal supported is 1 to 30% by weight, preferably 3 to 7% by weight of the activated carbon aerogels. When the supported precious metal is less than 1%, it is difficult to see the influence of the supported precious metal. When the supported precious metal is less than 30%, the specific surface area of the precious metal is reduced due to the aggregation of the precious metal supported on the activated carbon aerogels, thereby degrading the catalytic activity.

In the step (h), the noble metal oxide supported on the activated carbon airgel containing the acid point generated in the step (g) is reduced to hydrogen and converted into a noble metal form. The reduction is carried out in a hydrogen atmosphere at 120 DEG C for 5 to 12 hours.

In addition, the present invention uses a lignin model compound to simplify the complicated internal structure of lignin in lignin decomposition, and a model representative of the most frequently occurring carbon-oxygen bond (CO bond) Were selected. 4-phenoxyphenol, which is representative of 4-carbon-oxygen-5-carbon (4-O-5) bond having the highest binding energy among the carbon-oxygen bonds of lignin, was selected as a model compound. The structural formula of cyphenol was presented.

In addition, the present invention was carried out the decomposition reaction of the lignin model compound using a noble metal supported on the activated carbon airgel prepared above as a catalyst, the reaction is a liquid phase reaction in which the catalyst is dispersed in a solvent heterogeneously. The solvent that can be used for the reaction does not decompose on the noble metal catalyst supported on the activated carbon airgel containing acidic point, and a hydrocarbon material having a boiling point of 200 ° C. or higher was selected. In the present invention, hexadecane (C ₁₆ H ₃₄ ) was selected. It was.

In the present invention, in order to calculate the conversion rate of the lignin model compound, the amount of lignin before the reaction and the amount of lignin after the reaction were analyzed by gas chromatography. The amount of phenol, benzene and cyclohexanol produced as a result of 4-phenoxyphenol decomposition reaction was analyzed by gas chromatography, and the conversion of lignin model compound, selectivity and yield of main product (phenol + benzene + cyclohexanol) It was calculated using the following equation.

Production Example 1

In the present invention, a noble metal catalyst supported on an activated carbon airgel containing an acid point by treating a cation-substituted heteropolyacid was applied to a lignin model compound decomposition reaction. In order to include an acid point in the activated carbon aerogel, a process of preparing a cation-substituted heteropolyacid and a precious metal catalyst supported on the activated carbon aerogel having an acid point are shown in FIG. 3. The activated carbon aerogels were prepared by carbonizing the RF gels produced by polymerizing resocinol and formaldehyde. The carbon aerogels prepared above were activated by using phosphoric acid (H ₃ PO ₄ ) Respectively. The ratio of resorcinol to formaldehyde used is 0.5 and the ratio of sodium hydrogencarbonate used as catalyst is 1/200 in terms of resorcinol base weight ratio. Resorcinol and formaldehyde are dissolved in distilled water, respectively, and mixed in a single container. The calculated amount of catalyst is added to the fully mixed resorcinol and formaldehyde solution to initiate the polymerization reaction. The polymerization initiated resorcinol / formaldehyde mixed solution is placed in a sealed container and reacted at 100 ° C for 10 hours to produce a solid RF gel. The solid RF gel is washed with acetone and dried at 80 ° C for 5 hours. The dried RF gel is carbonized at 500 ° C for 1 hour under a nitrogen atmosphere to produce carbon aerogels (CA). The carbon aerogels produced above are mixed by impregnation with phosphoric acid and sufficiently dried at 100 ° C. The proportion of phosphoric acid used as active substance is used twice by weight based on carbon airgel. Carbon aerogels impregnated with phosphoric acid are carbonized and activated at 800 ° C. for 1 hour in a nitrogen atmosphere to produce an activated carbon aerogel (ACA). The activated carbon aerogels are washed with distilled water and rinsed until the pH of the wash water is between 6.5 and 7. The washed activated carbon aerogels are dried at 110 ° C for 3 hours.

The impregnation method is used to treat cationic substituted heteropolyacids to add an acid point to an activated carbon aerogel (ACA), the heteropolyacid used is 12- tungstoic acid (H ₃ PW ₁₂ O ₄₀ ), and the substituted cations Cesium precursors are used. The activated carbon aerogels are treated with aqueous solution of heteropoly acid by impregnation method and dried at 80 ° C for 3 hours. Cationic substitution of the dried activated carbon aerogels with a predetermined amount of aqueous cesium precursor, followed by calcining at 250 ° C. for 5 hours to treat activated carbon aerogels treated with cationic substituted heteropolyacids (YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40, and 50% by weight). The amount of treated cationic heteropolyacid represented by Y is 10 to 50% by weight based on activated carbon aerogel, and the amount of substituted cation cesium is set at 2.5 molar ratio. In order to support palladium, a palladium precursor (palladium nitrate, Pd (NO ₃ ) ₂ ) is dissolved in distilled water and impregnated in activated carbon aerogels. The amount of palladium supported on the activated carbon aerogels containing the acid sites is 5 wt%, and the mixture is calcined at 250 DEG C for 2 hours to produce palladium oxide-supported active carbon aerogels containing acid sites. In order to reduce the palladium oxide supported on the activated carbon aerogel containing the acid point which has been calcined, it is reduced at 120 ° C. for 10 hours in a hydrogen atmosphere (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30 , 40, and 50% by weight) is used as a lignin model compound decomposition catalyst.

Comparative Preparation Example 1

The cation-substituted heteropolyacid produced in Preparation Example 1 was treated on an activated carbon aerogel to compare the catalytic performance with a palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on an activated carbon aerogel containing an acid point. Palladium catalyst (Pd / ACA, ACA is Activated Carbon Aerogel) was prepared. The ratio of resorcinol to formaldehyde used in the preparation of the carbon aerogels is 0.5, and the ratio of sodium hydrogencarbonate used as the catalyst is 1/200 as a resorcinol-based weight ratio. Resorcinol and formaldehyde are dissolved in distilled water, respectively, and mixed in a single container. The calculated amount of catalyst is added to the fully mixed resorcinol and formaldehyde solution to initiate the polymerization reaction. The polymerization initiated resorcinol / formaldehyde mixed solution is placed in a sealed container and reacted at 100 ° C for 10 hours to produce a solid RF gel. The solid RF gel produced above is washed with acetone and then dried at 80 ° C. The dried RF gel is carbonized at 800 ° C under a nitrogen atmosphere for 1 hour to produce carbon aerogels. Phosphoric acid is mixed in each of the carbon aerogels produced by impregnation, followed by drying at 100 ° C. The proportion of phosphoric acid used as active substance is used twice by weight based on carbon airgel. Carbon aerogels impregnated with phosphoric acid are carbonized and activated at 800 DEG C for 1 hour in a nitrogen atmosphere. The activated carbon aerogels are washed with distilled water and rinsed until the pH of the wash water is between 6.5 and 7. The washed activated carbon aerogels are dried at 110 ° C for 3 hours. The catalyst supporting the palladium on the activated carbon airgel produced above was prepared by the impregnation method, and the palladium metal was supported by 5 wt% based on the activated carbon airgel and calcined at 250 ° C. for 2 hours to activate the activated carbon airgel loaded with palladium oxide. To prepare. In order to reduce the precious metal oxide supported on the activated carbon airgel to the precious metal, the precious metal oxide supported on the carbon airgel is reduced at 120 ° C. for 10 hours in a hydrogen atmosphere to be used as a catalyst (Pd / ACA, ACA is an activated carbon aerogel).

Comparative Production Example 2

Commercial activated carbon to compare the degradation performance of lignin model compound with palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on activated carbon airgel containing acidic acid by treatment with cationic substituted heteropolyacid produced in Preparation Example 1 The Pd / AC (AC: commercially activated carbon) catalyst was prepared by supporting palladium metal. The commercial activated carbon used above used Kanshai's MSP 20 product. The catalyst supporting palladium on commercial activated carbon was prepared by impregnation, and the palladium metal was supported by 5 wt% based on commercial activated carbon and calcined at 250 ° C. for 2 hours to prepare a material in which precious metal oxide was supported on commercial activated carbon. In order to reduce the precious metal oxide supported on the commercial activated carbon to the precious metal, it is reduced for 10 hours in a hydrogen atmosphere at 120 ° C. and used as a catalyst (Pd / AC, commercially activated carbon).

Example 1

The cesium ion-substituted heteropolyacid produced in Preparation Example 1 was treated with a palladium catalyst supported on an activated carbon airgel formed with acid spots, and subjected to lignin model compound decomposition reaction. The lignin degradation reaction occupied the highest frequency of lignin interactions and used 4 - phenoxyphenol which is representative of carbon - oxygen bond. To decompose 4-phenoxyphenol, a high-temperature high-pressure vessel reactor was used, and hexadecane was used as a solvent. The reaction temperature was carried out for 1 hour in a hydrogen atmosphere of 200 ℃, 10 atmospheres, the palladium catalyst (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ supported on the activated carbon airgel containing 4-phenoxyphenol and acid point / ACA, Y = 10, 20, 30, 40, and 50% by weight).

Comparative Example 1

Produced in Comparative Preparation Example 1 to verify the performance of a palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on activated carbon aerogels formed by treating cesium ion-substituted heteropolyacids applied in Example 1 Palladium catalyst (Pd / ACA) supported on activated carbon airgel was subjected to the lignin decomposition reaction. The lignin degradation reaction occupied the highest frequency of lignin interactions and used 4 - phenoxyphenol which is representative of carbon - oxygen bond. To decompose 4-phenoxyphenol, a high-temperature high-pressure vessel reactor was used, and hexadecane was used as a solvent. The reaction temperature was maintained at 200 ° C under a hydrogen atmosphere of 10 atmospheres for 1 hour. The weight ratio of 4-phenoxyphenol and palladium catalyst (Pd / ACA) supported on carbon aerogels was 20.

Comparative Example 2

Produced in Comparative Preparation Example 2 to verify the performance of a palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on activated carbon aerogels formed by treating cesium ion-substituted heteropolyacids applied in Example 1 The palladium catalyst (Pd / AC, AC is a commercial activated carbon) supported on the commercially available activated carbon was applied to the lignin decomposition reaction. The lignin degradation reaction occupied the highest frequency of lignin interactions and used 4 - phenoxyphenol which is representative of carbon - oxygen bond. A high-temperature high-pressure vessel reactor was used to decompose 4-phenoxyphenol, and hexadecane was used as a solvent. The reaction temperature was carried out for 1 hour in a hydrogen atmosphere of 200 ℃, 10 atm, the weight ratio of the palladium catalyst (Pd / AC) supported on the activated carbon containing 4-phenoxyphenol and cesium ion-substituted heteropoly acid charged in the reaction is 20.

Palladium catalyst (Pd / YCs) supported on activated carbon airgel formed by treating cesium ion-substituted heteropolyacid _x H _3.0-x PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40, and 50% by weight)

Specific surface area of palladium catalyst (Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA, Y = 10, 20, 30, 40, and 50% by weight) supported on activated carbon aerogels formed by treating cationic substituted heteropolyacids And pore sizes are shown in Table 1. As the amount of cation-substituted heteropolyacids contained in activated carbon aerogels increased from 10% to 50% by weight, it decreased from 1385 m ² / g to 636 m ² / g and the pore size was observed almost constant at 4.1-4.6 nm. It became. As the amount of the cation-substituted heteropolyacid included in the activated carbon airgel increases, the specific surface area decreases because the amount of the cation-substituted heteropolyacid having a relatively small specific surface area increases. Figure 4 shows the nitrogen adsorption and desorption curves of the catalyst Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA (Y = 10, 20, 30, 40, and 50% by weight) catalyst. Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA (Y = 10, 20, 30, 40, and 50 wt%) The catalytic nitrogen adsorption and desorption curves were all observed in type 4 pore morphology. 5 shows the XRD pattern of the crystal structure of Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA (Y = 10, 20, 30, 40, and 50% by weight) catalyst. Dispersion degree of cationic substituted heteropolyacid catalyst for Pd / 10Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA and Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA catalyst High, no heteropoly acid related peaks are observed. On the other hand, in the case of a catalyst containing more than 30% by weight of cation-substituted heteropolyacid, the crystal structure of the heteropolyacid is confirmed by the XRD pattern. 6 shows TEM images of Pd / YCs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA (Y = 10, 20, 30, 40, and 50 wt%) catalysts. In the TEM image, it was observed that the palladium metal particles were distributed between 10-20 nm, and in the case of a catalyst containing more than 30% by weight of cation-substituted heteropolyacid, a heteropolyacid image was observed.

catalyst Specific surface area (m ² / g) Pore size (nm) Pd / 10Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA 1385 4.6 Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA 932 4.7 Pd / 30Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA 923 4.8 Pd / 40Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA 723 4.7 Pd / 50Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA 636 4.1

Palladium catalyst (Pd / YCs) supported on activated carbon airgel containing acid point by treatment of cesium ion-substituted heteropolyacid _2.5 H _0.5 PW ₁₂ O ₄₀ / Phenaphenol decomposition reaction with (ACA, Y = 10, 20, 30, 40, and 50% by weight)

In the decomposition of 4-phenoxyphenol, which is a lignin model compound, the reaction was carried out as in Example 1 for the performance evaluation of the palladium catalyst supported on the activated carbon aerogel containing an acid point by treating a cation-substituted heteropolyacid. The products produced in the 4-phenoxyphenol decomposition reaction were benzene, cyclohexanol, and phenol, respectively, identified by GC-MS. The conversion, selectivity, and yield are calculated according to equations (1), (2), and (3) to evaluate the catalytic activity after catalytic cracking of 4-phenoxyphenol. As shown in Example 1, the result of decomposing the lignin model compound 4-phenoxyphenol using a palladium catalyst supported on an activated carbon airgel treated with a cation-substituted heteropolyacid to form an acid point is shown in FIG. 7. As shown in FIG. 7, 4-phenoxyphenol conversion and main product yield show volcanic graphs depending on the amount of cationic substituted heteropolyacids included in the catalyst. When the cationic substituted heteropolyacid included in the catalyst is 20% by weight (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) among the catalysts described above, the conversion and main product yields are 93.7% and 66.5%, respectively. In addition, when the amount of cation-substituted heteropolyacid is between 10% and 50% by weight, the conversion is between about 80-95% and the main product yield is observed between about 45-67%.

Treatment of cesium ion-substituted heteropolyacids, palladium catalyst (Pd / 20Cs) supported on activated carbon airgel containing acid _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA), Palladium Catalyst Supported on Activated Carbon Aerogels (Pd / ACA), Palladium Catalyst Supported on Commercial Activated Carbon (Pd / AC)

8 shows the palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on the activated carbon aerogels containing acidic acid by treating the cation-substituted heteropolyacids carried out in Examples 1 and 2 and the activated carbon aerogels. Decomposition of the lignin model compound 4-phenoxyphenol with the palladium catalyst supported on (Pd / ACA) and the palladium catalyst supported on commercial activated carbon (Pd / AC) is shown. When the 4-phenoxyphenol is decomposed using a palladium catalyst (Pd / AC) catalyst supported on commercial activated carbon, the conversion and main product yields are 40.5% and 13.7%, respectively. In addition, the conversion and main product yields of 62.4% and 49.9%, respectively, were obtained when the 4-phenoxyphenol was decomposed using a palladium catalyst (Pd / ACA) supported on activated carbon aerogels. In contrast, the conversion and main product of the decomposition of 4-phenoxyphenol using a palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on activated carbon aerogels containing acidic acid by treating cationic substituted heteropolyacids Yields of 93.7% and 66.5% were observed. When the 4-phenoxyphenol was decomposed using the above three catalysts, the conversion and the yield of the main product were observed in the order of Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA> Pd / ACA> Pd / AC. The palladium catalyst (Pd / 20Cs _2.5 H _0.5 PW ₁₂ O ₄₀ / ACA) supported on the activated carbon aerogel containing the acid point by treating the cation-substituted heteropolyacid showed the best 4-phenoxyphenol degrading performance.

The embodiments of the present invention described above should not be construed as limiting the technical idea of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and those skilled in the art will be able to modify the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the scope of the present invention as long as they are obvious to those skilled in the art.

Claims (3)

Used to prepare aromatic compounds by selectively decomposing carbon-oxygen-carbon bonds among the internal bonds of lignin compounds,
Formula M / Q _x H _3.0-x PW ₁₂ O ₄₀ / ACA (M is a noble metal, Q _x H _3.0-x PW ₁₂ O ₄₀ is a cation-substituted heteropolyacid, wherein Q is one selected from alkali metal ions or ammonium ions) Or more cations, 0 ≦ x ≦ 3, ACA is an activated carbon aerogel), and a cation-substituted heteropolyacid in which hydrogen ions are substituted with at least one cation selected from alkali metal ions or ammonium ions, based on the weight of the activated carbon aerogel. 1 to 30% by weight based on the weight of the activated carbon airgel of at least one precious metal catalyst selected from the group consisting of palladium, rhodium, ruthenium and platinum on the activated carbon airgel formed in the range of 5 to 70% by weight A noble metal catalyst supported on an activated carbon aerogel comprising a cation-substituted heteropolyacid, which is supported in a range. The method of claim 1, wherein the activated carbon airgel is a carbon airgel produced by polymerizing resorcinol and formaldehyde (R / F ratio) in the range of 0.1 ~ 2.0 of resocinol and formaldehyde (R / F ratio) Activated carbon aerogels containing cation-substituted heteropolyacids, which are activated in a temperature range of 200 to 800 ° C. for 1 to 3 hours and in a nitrogen atmosphere with at least one activator selected from the group consisting of potassium hydroxide, phosphoric acid, and zinc chloride. Supported Precious Metal Catalysts. An aromatic compound is prepared by decomposing a lignin compound at a temperature of less than 300 ° C. and a pressure of 50 atm or less of hydrogen in the presence of a noble metal catalyst supported on an activated carbon aerogel including the cationic substituted heteropolyacid of claim 1. Method for Degrading Lignin Compounds.

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