KR20150077065A - Hydrogenation catalyst having metal catalyst-core/carbon-shell structure, preparation method thereof, and use thereof - Google Patents

Abstract

The present invention relates to a hydrogenation catalyst having a metal catalyst (core)/carbon (shell) structure and a manufacturing method thereof, and more specifically, to a hydrogenation catalyst which prevents leaching of reactive metal and has high stability in terms of a liquid hydrogenation reaction of an organic acid such as a levulinic acid. Furthermore, the manufacturing method comprises: a first step of preparing a mixed solution containing a metal catalyst precursor and a carbon precursor; a second step of forming a metallic oxide particle that carbon species are embedded from the mixed solution by radiating ultrasonic waves to the mixed solution; and a third step of vivifying a part or the entire of a metallic oxide and forming a carbon shell on the particle surface through a heat treatment which spreads the carbon species inside the metallic oxide particle to the surface.

Description

TECHNICAL FIELD The present invention relates to a hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure, a process for producing the same,

The present invention relates to a hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure and a process for producing the same, and more particularly, to a process for producing a hydrogenation catalyst which prevents leaching of an active metal in a liquid hydrogenation reaction of an organic acid such as levulinic acid, (Core) / carbon (shell) structure having a metal catalyst and a process for producing the same. The present invention further relates to a process for preparing a cyclized compound using the liquid hydrogenation catalyst.

In a method for producing a lactone compound containing a general gamma -valerolactone (GVL), a gaseous or liquid hydrogenation reaction is carried out under a catalyst to obtain a lactone compound such as gamma-valerolactone (GVL) from levulinic acid And a process for applying a more economical catalyst and process to the hydrogenation reaction have been carried out.

As a catalyst for producing gamma-valerolactone (GVL) by hydrogenating levulinic acid, a catalyst mainly composed of a noble metal is used. For example, U.S. Patent No. 5883266 shows a high yield as a Pd-Re-based catalyst, and U.S. Patent No. 2003/0055270 and WO2002 / 074760 disclose that Ru, Pd, Rh and Pt are replaced by C, SiO ₂ , TiO ₂ , Al ₂ O ₃ , and zeolites. Also, in Applied Cat. A general, 272 (2004), 249 discloses a process for obtaining a high yield using a 5% Ru / Carbon catalyst. However, since the main component of the catalyst used in this process is a noble metal and it operates at a relatively high hydrogen pressure, there are problems in terms of economy and safety. In addition, when the hydrogenation reaction of levulinic acid proceeds in a high-pressure liquid phase, there is a problem in that the active metal carried in the support is leached.

Furthermore, levulinic acid, which is a raw material for producing gamma-valerolactone (GVL), is usually produced from glucose through a biomass conversion reaction. This biomass conversion reaction is generally carried out in a liquid phase reaction using a homogeneous acid catalyst (acid or aqueous acid solution). Therefore, as mentioned above, in the hydrogenation reaction of levulinic acid, when the hydrogenation reaction is carried out in the gas phase to prevent leaching of the metal catalyst in the liquid phase, after the biomass conversion reaction, There is a problem that it must be separated separately.

On the other hand, nanoparticles having a metal (Fe, Co, Ni, etc.) core / carbon shell structure have been developed and they have been applied to various fields such as electronic parts, data memories, sensors, biological tags and drug delivery systems Has come. Various methods for manufacturing nanoparticles in which metal particles are encapsulated with carbon have been reported as described above. For example, an arc discharge (RS Ruoff, et al., Single Crystal Metals Encapsulated in Carbon Nanoparticles, Subramoney, Science 1993, 259 , 346), thermal decomposition of non-graphitizable carbon (PJF Harris et al., A Simple Technique for Filled Carbon Nanoparticles, Chem. There have been studies in which nanoparticles have been prepared using methods such as those described in, for example, Controlled Synthesis of Carbon-Encapsulated Co Nanoparticles by CVD, Chem. However, the above methods are uneconomical and have a low yield of particles. Furthermore, there has been no report on the use of the carbon-encapsulated metal nanoparticles as a catalyst for liquid hydrogenation of an organic acid.

Under these circumstances, the present inventors have found that when a liquid hydrogenation reaction of an organic acid is carried out by using a hydrogenation catalyst of a metal catalyst (core) / carbon (shell) structure, the porous carbon shell formed on the surface of the metal catalyst core particles, It is confirmed that the catalyst stability can be improved by preventing the leaching of the active metal. Furthermore, it was confirmed that the liquid hydrogenation reaction at a relatively low pressure of 5 bar or less, rather than high pressure, has high yield and high selectivity. The present invention is based on this.

A first aspect of the present invention relates to a metal catalyst core particle; And a porous shell made of carbon and formed on the surface of the metal catalyst core particle, wherein the metal catalyst precursor and the carbon precursor A first step of preparing a mixed solution; A second step of irradiating ultrasonic waves to the mixed solution to form metal oxide particles embedded in carbon paper from the mixed solution; And a third step of forming a carbon shell on the surface of the particles while reducing part or all of the metal oxide through heat treatment for diffusing the carbon species inside the metal oxide particles to the surface.

A second aspect of the present invention is a process for producing a metal catalyst core particle; And a porous shell made of carbon and formed on the surface of the metal catalyst core particle. The present invention provides a liquid hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure.

A third aspect of the present invention is a method for producing a cyclized compound by hydrogenating a solution containing an ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms in the presence of hydrogen, Wherein the hydrogenation catalyst or the liquid phase hydrogenation catalyst of the second aspect is used.

A fourth aspect of the present invention is a metal catalyst particle comprising: a metal catalyst core particle; And a porous shell made of carbon, which is formed on the surface of the metal catalyst core particle, in a process for producing a catalyst having a metal catalyst (core) / carbon (shell) structure and an average diameter of 20 nm to 1000 nm A metal catalyst precursor, and a carbon precursor-containing mixed solution; A second step of irradiating ultrasonic waves to the mixed solution to form metal oxide particles embedded in carbon paper from the mixed solution; And a third step of forming a carbon shell on the surface of the particles while reducing part or all of the metal oxide through heat treatment for diffusing the carbon species inside the metal oxide particles to the surface.

Hereinafter, the present invention will be described in detail.

The present invention provides a novel method for preparing a nanoparticle catalyst using ultrasonic irradiation and heat treatment in the production of a carbon-encapsulated metal nanoparticle catalyst having a metal catalyst (core) / carbon (shell) structure. This can provide nanoparticles with an average diameter of between 20 nm and 1000 nm, which can vary the average diameter more widely than conventional carbon-encapsulated metal nanoparticle manufacturing methods.

Further, the present invention provides a novel use of carbon-encapsulated metal nanoparticles having a metal catalyst (core) / carbon (shell) structure as a catalyst for the hydrogenation reaction of ester compounds of organic acids or organic acids having 4 to 6 carbon atoms. Particularly, since the carbon shell is chemically inert to air, acid, water and the like, and stable and lipophilic from the external high-temperature and high-pressure environment, the metal core inside the shell can be effectively protected. Thus, the hydrogenation catalyst according to the present invention can prevent leaching of a metal catalyst (active metal), which is a metal core, under a high-temperature, high-pressure liquid hydrogenation reaction environment, and significantly reduces the damage thereof from the outside, . In addition, due to the improvement in stability, the hydrogenation catalyst according to the present invention can maintain its catalytic activity even when it is reused. Furthermore, since the carbon shell is porous, the inner metal core can effectively contact with the reactants to promote the chemical reaction and improve the yield and selectivity.

Since the hydrogenation catalyst having the metal catalyst (core) / carbon (shell) structure according to the present invention can be reacted in a liquid phase, it is possible to separate and purify levulinic acid separately from the liquid product after the biomass conversion reaction The liquid hydrogenation process can be carried out directly without the need. Therefore, the biomass-derived chemical product can be efficiently produced by continuously operating the process.

Metal catalyst core particles according to the present invention; And a porous shell made of carbon and formed on the surface of the metal catalyst core particle. The method for producing a hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure comprises the steps of mixing a metal catalyst precursor and a carbon precursor- A first step of preparing a first step; A second step of irradiating ultrasonic waves to the mixed solution to form metal oxide particles embedded in carbon paper from the mixed solution; And a third step of forming a carbon shell on the surface of the particles while reducing part or all of the metal oxide through heat treatment for diffusing the carbon species inside the metal oxide particles to the surface.

The first step of the present invention is a step of preparing a mixed solution containing a metal catalyst precursor and a carbon precursor, wherein a metal source and a carbon source of the hydrogenation catalyst particles are prepared in the form of a mixture.

The metal catalyst precursor is a metal precursor compound to be used as a catalytically active component and is not particularly limited as long as it is a metal precursor compound that can be used for the liquid hydrogenation reaction of an organic acid. Non-limiting examples thereof include iron (III) acetylacetonate, aluminum acetylacetonate, titanium (IV) oxide acetylacetonate, cerium (IV) III) Acetylacetonate, Cerium (III) acetylacetonate, Hydrate, Chromium (III) acetylacetonate, Cobalt (II) acetylacetonate, Copper (II) acetylacetonate, gallium (III) acetylacetonate, manganese (III) acetylacetonate, iron (II) acetylacetonate, II) acetylacetonate, magnesium acetylacetonate (hydrate), barium acetylacetonate (hydrate), beryllium acetylacetonate, cadmium acetylacetonate (III) acetylacetonate, iridium (III) acetylacetonate (Iridium (III) acetylacetonate), cadmium acetylacetonate, cadmium acetylacetonate, cadmium acetylacetonate hydrate, calcium acetylacetonate, cesium acetylacetonate, indium (III) acetylacetonate, lanthanum acetylacetonate, hydrate, lead (II) acetylacetonate, lithium acetylacetonate, manganese (II) acetylacetonate Manganese (II) acetylacetonate, Nickel (II) acetylacetonate, Palladium (II) acetylacetonate, Platinum (II) acetylacetonate ), Rhodium (III) acetylacetonate, rubidium acetylacetonate, ruthenium (III) acetylaceto nate), silver acetylacetonate, vanadium (III) acetylacetonate, vanadyl acetylacetonate, yttrium (III) acetylacetonate, , hydrate, zinc acetylacetonate hydrate, zirconium (IV) acetylacetonate, and mixtures thereof, and may be selected therefrom. Preferably, iron (Fe) and copper (Cu) precursor compounds can be used because it is more economical to use a metal that is not a noble metal in view of the economical efficiency of the catalyst. Specifically, it may be selected from the group consisting of iron (III) acetylacetonate, iron (II) acetylacetonate, copper (II) acetylacetonate and mixtures thereof.

The carbon precursor is a precursor compound of carbon which forms a shell of catalyst particles, and at the same time, can act as an organic solvent in the production step. Specifically, the carbon precursor may be a C4 to C12 alkyl ether, but is not particularly limited.

The second step is a step of forming a metal oxide particle embedded in carbon paper from the mixed solution by irradiating ultrasonic waves to the mixed solution, and by irradiating ultrasonic wave to the mixed solution of the first step, So that the metal oxide particles embedded in the carbon paper are grown.

When ultrasonic treatment is applied to a mixed solution of a metal catalyst precursor and a carbon precursor, acoustic cavitation phenomenon may occur and crystal nucleation of the metal catalyst precursor may be triggered. As the crystal nuclei gradually grow according to ultrasonic irradiation, metal oxide particles are formed. At the same time, a carbon precursor is implanted to form carbon species inside the metal oxide particles. Specifically, FIG. 1 shows that carbon paper is embedded on the surface and inside of the metal oxide particles formed by ultrasonic irradiation.

In the present invention, the ultrasonic wave irradiation in the second step may be carried out in the following manner: specifically, the frequency of the ultrasonic waves is 1 to 100 kHz, the output amplitude of the ultrasonic waves is 40% to 60% But is not limited thereto. During the irradiation of the ultrasonic waves, the temperature of the mixed solution may gradually increase. At this time, it is preferable to irradiate ultrasonic waves so that the temperature of the mixed solution due to the ultrasonic irradiation is finally 30 ° C to 300 ° C. And the ultrasonic device can be appropriately changed and adopted by those skilled in the art.

In one embodiment of the present invention, when ultrasonic wave is irradiated to the mixed solution using iron (III) acetylacetonate as the metal catalyst precursor, α-Fe ₂ O ₃ (hematite) iron oxide It was confirmed that particles were generated.

The carbon species is a carbon-atom-containing compound derived from the carbon precursor of the first stage, and is a carbon skeleton-based compound produced through ultrasonic irradiation. By performing the ultrasonic irradiation in the second step, various carbon skeleton-based compounds can be generated from the carbon precursor (C4 to C12 alkyl ether) and can be incorporated into the particles, and the generated carbon species may vary considerably , The kind of the carbon species is not particularly limited.

When the growth of the metal oxide particles in the second step is completed, the solution may be centrifuged after the second step and washed with a solvent to separate and obtain the metal oxide particles.

The third step is a step of forming a carbon shell on the particle surface while reducing part or all of the metal oxide through a heat treatment for diffusing the carbon species inside the metal oxide particle to the surface, , The carbon species embedded in the particles are diffused to the surface of the particles through the heat treatment and the carbon species acts as a reducing agent to reduce metal oxides of the particles to metal.

In the third step, the present inventors confirmed that when the heat treatment is performed in a specific temperature range, the carbon particles in the particles are diffused to form a porous shell of carbon on the surface of the particles, and a schematic diagram thereof is shown in FIG. Specifically, the heat treatment in the third step may be performed at 300 ° C to 1000 ° C, and the carbon paper may diffuse under the heat treatment temperature range to form a porous shell on the surface.

Studies have been conducted on the use of carbon species embedded in the conventional grains as a reducing agent for rare earth oxides. For example, research has been conducted on reduction of Eu ^{3 +} -containing material by heat treatment under an embedded carbon species (BC Hong et al., Reduction of Eu2 + -activated nanoparticles by unique TCRA treatment, J. Alloy Compd. 2008, 451, 276.). In the present invention as well, the carbon species embedded in the metal oxide particles can act as a reducing agent for the metal oxide, and thus the metal oxide can be gradually reduced to the metal during the heat treatment in the third step.

In one embodiment of the present invention, the α-Fe ₂ O ₃ (hematite) iron oxide particles formed by irradiation with ultrasonic waves were heat-treated at a temperature of 700 ° C. As a result, Thereby forming a porous shell of carbon on the surface of the particles. Further, at the same time, the α-Fe ₂ O ₃ of the iron oxide particles gradually changed to the following form and was confirmed to be reduced (FIG. 2 and FIG. 3):

? -Fe ₂ O ₃ ? -Fe ₂ O ₃ ? Fe ₃ O ₄ ? Fe

The above reduction is characterized by the fact that it occurred without additional reducing agent (for example, H ₂ gas), and it can once again be confirmed that carbon in the particles can also act as a reducing agent.

The heat treatment in the third step is preferably carried out sufficiently until the carbon paper is sufficiently diffused to form a shell having a sufficient thickness while maintaining the heat treatment temperature range, and further, the metal oxides of the particles are mostly reduced to metal.

Through the first through third steps, a carbon-encapsulated metal nanoparticle catalyst having a metal catalyst (core) / carbon (shell) structure can be prepared. It was confirmed that the catalyst prepared by the method according to the present invention had an average diameter of about 300 nm.

The hydrogenation catalyst prepared through the first to third steps can be used as an economical and effective catalyst, especially for the liquid hydrogenation reaction.

A liquid hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure according to the second aspect of the present invention comprises: a metal catalyst core particle; And a porous shell made of carbon and formed on the surface of the metal catalyst core particle.

An exemplary structure of the liquid hydrogenation catalyst according to the present invention is as shown in Fig. Specifically, a portion corresponding to the active metal in the catalyst forms the inner core of the particle (metal catalyst core), and a porous shell is formed of carbon surrounding the surface of the core.

The carbon shell is highly stable against external compounds and environmental conditions and increases the lipophilicity of the particles, thereby effectively protecting the metal catalyst core formed inside the shell. Therefore, leaching of the metal catalyst (active metal), which is a metal core, can be prevented under a high temperature and high pressure liquid hydrogenation reaction environment. In addition, it was confirmed that the hydrogenation catalyst according to the present invention has improved stability and can maintain the catalytic activity even when reused (Experimental Example 2, Table 2, and FIG. 7). Furthermore, since the shell is porous, the inner metal catalyst core can effectively contact the reactants and have high yield and high selectivity.

The metal catalyst may be used as a metal catalyst that can be used for the liquid hydrogenation reaction of an organic acid without particular limitation, and may be different depending on whether a metal catalyst precursor is used in the production process. In consideration of the economical efficiency of the catalyst, specifically, the metal catalyst may be selected from the group consisting of Fe, Fe oxide, Cu, Cu oxide, and mixtures thereof, but is not particularly limited.

The liquid hydrogenation catalyst may be nanoparticles having an average diameter of 20 nm to 1000 nm, wherein the porous shell may have an average thickness of 1 nm to 100 nm.

The liquid hydrogenation catalyst may have a specific surface area of 50 to 1000 m ² / g and a pore volume of 0.05 to 1.0 ml / g. Since the specific surface area and the pore volume are large, Can be efficiently performed.

In the present invention, the metal catalyst constituting the core may be 50 to 99% by weight based on the total weight of the liquid hydrogenation catalyst. If it is lower than the lower limit of the numerical range, the catalytic activity may not be properly manifested. If the upper limit is larger than the upper limit, there is hardly any porous shell. Thus, it is difficult to effectively protect the metal catalyst core.

The liquid hydrogenation catalyst having the metal catalyst (core) / carbon (shell) structure can be produced by the production method according to the first aspect (ultrasonic irradiation and heat treatment). However, the present invention is not limited thereto, and can be produced according to a method for producing nanoparticles having a conventional metal core / carbon shell structure. That is, the present invention is characterized in that the metal catalyst encapsulated in the carbon shell is used as a catalyst for the liquid hydrogenation reaction of an ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms, rather than simply supported on a carbon support. Such as a catalyst, according to the method of the present invention. Specifically, methods such as arc discharge, pyrolysis of non-graphitizable carbon, or chemical vapor deposition can be used.

In the present invention, the "liquid hydrogenation catalyst" may be, for example, a catalyst particle used for performing hydrogenation reaction of an ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms in the liquid phase in the presence of hydrogen.

According to a third aspect of the present invention, there is provided a method for producing a cyclized compound by hydrogenating a solution containing an ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms in the presence of hydrogen, The hydrogenation catalyst or the liquid phase hydrogenation catalyst of the second embodiment is used.

In the present invention, considering that the hydrogenation reaction of an ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms is carried out at 150 ° C or more, specifically 150 to 350 ° C, the dehydration reaction of an organic acid having 4 to 6 carbon atoms, It is preferable that the catalyst has neutrality in order to obtain high selectivity. Therefore, catalyst particles composed of a metal catalyst (core) / carbon (shell) structure corresponding to the hydrogenation catalyst produced by the production method according to the first aspect of the present invention or the liquid hydrogenation catalyst of the second aspect of the present invention, It is effective to achieve the purpose.

The hydrogenation reaction can be carried out in a liquid phase reaction using a solution containing an ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms, specifically at a reaction temperature of 150 to 350 ° C and a reaction pressure of 1 to 20 bar. In particular, a liquid hydrogenation reaction using a noble metal catalyst requires a high hydrogen pressure of 20 atm or higher, whereas when a liquid hydrogenation catalyst according to the present invention is used, the reaction is performed at a lower pressure (for example, 5 bar) , The leaching of the active metal in the catalyst does not occur, and further, the conversion of the reactant, the yield and the selectivity of the product are excellent.

The solution containing the ester compound of an organic acid or an organic acid having 4 to 6 carbon atoms may be an aqueous solution, but is not particularly limited.

The organic acids having 4 to 6 carbon atoms include levulinic acid, succinic acid, fumaric acid, itaconic acid, aspartic acid, adipic acid, ) And glucaric acid, and is preferably selected from levulinic acid, succinic acid, fumaric acid and adipic acid, more preferably levulinic acid.

The cyclized compound may be a lactone compound or a heterocyclic compound containing oxygen.

Specifically, when the organic acid is levulinic acid, gamma-valerolactone (GVL) and 2-methyltetrahydrofuran, when the organic acid is succinic acid or fumaric acid, butyrolactone and tetrahydrofuran, when the organic acid is itaconic acid, 3- Methylbutyrolactone and 3-methyltetrahydrofuran, aspartic anhydride and 3-aminotetrahydrofuran when the organic acid is aspartic acid, E-caprolactone and oxepane when the organic acid is adipic acid, If it is an acid, it can be obtained as a cyclized compound in which the glucaro-δ-lactone and the glucaro-γ-lactone are hydrogenation products. Preferably, the organic acid is levulinic acid and the cyclized compound may be gamma-valerolactone.

Before performing the hydrogenation reaction, the hydrogenation catalyst according to the present invention may be activated by reducing the hydrogen-containing reducing gas at 50 ° C to 500 ° C before filling the reactor and supplying the reactants.

Metal catalyst core particles according to the fourth aspect of the present invention; And a porous shell made of carbon, which is formed on the surface of the metal catalyst core particle. The method for producing a catalyst having a metal catalyst (core) / carbon (shell) structure and having an average diameter of 20 nm to 1000 nm, A first step of preparing a mixed solution containing a catalyst precursor and a carbon precursor; A second step of irradiating ultrasonic waves to the mixed solution to form metal oxide particles embedded in carbon paper from the mixed solution; And a third step of forming a carbon shell on the surface of the particles while reducing part or all of the metal oxide through heat treatment for diffusing the carbon species inside the metal oxide particles to the surface.

As described above, the method of preparing nanoparticle catalyst using ultrasonic irradiation and heat treatment according to the present invention can provide nanoparticles having an average diameter of 20 nm to 1000 nm, which can be achieved by using carbon nanoparticles prepared by a conventional method The average diameter is remarkably improved.

A detailed description of a method for producing a catalyst having a metal catalyst (core) / carbon (shell) structure according to the fourth aspect is given below in detail with reference to a hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure according to the first embodiment As described in the production method.

The hydrogenation catalyst having a metal catalyst (core) / carbon (shell) structure according to the present invention and a production method thereof prevent leaching of an active metal in a liquid hydrogenation reaction of an organic acid such as levulinic acid and have high stability, The catalyst activity is maintained. Furthermore, it is possible to promote the chemical reaction under relatively low-pressure reaction conditions and improve the yield and selectivity of the cyclized compound such as gamma-valerolactone. In addition, since the liquid hydrogenation reaction is used, the biomass-derived chemical product can be efficiently produced by continuously operating the process.

FIG. 1 is a schematic diagram of a process for preparing a hydrogenation catalyst having an Fe catalyst (core) / carbon (shell) structure by ultrasonic irradiation and heat treatment according to an embodiment of the present invention.
FIG. 2 is an FE-SEM image and HR-TEM image showing the reduction process of α-Fe ₂ O ₃ iron oxide particles in a heat treatment process in the hydrogenation catalyst production process according to an embodiment of the present invention.
Figure 3 shows an FE-SEM image (Figure 3a), a TEM image (Figure 3b) and an HR-TEM image (Figure 3c) of a hydrogenation catalyst having a Fe catalyst (core) / carbon (shell) structure according to one embodiment of the present invention. )to be.
FIG. 4 is a graph showing a result of a nitrogen adsorption method using a BET equipment for a hydrogenation catalyst having a Fe catalyst (core) / carbon (shell) structure according to an embodiment of the present invention.
FIG. 5 is a graph showing the results of liquid hydrogenation of levulinic acid using a hydrogenation catalyst having Fe catalyst (core) / carbon (shell) structure according to one embodiment of the present invention with respect to time.
6 shows XRD data of the catalyst before and after the reaction in the liquid hydrogenation reaction of levulinic acid using a hydrogenation catalyst having a Fe catalyst (core) / carbon (shell) structure according to an embodiment of the present invention Graph.
FIG. 7 is a graph showing the results of liquid hydrogenation of levulinic acid using a hydrogenation catalyst having a Fe catalyst (core) / carbon (shell) structure according to an embodiment of the present invention with respect to the number of times of reuse.
8 is a graph showing XRD data of the catalyst for repetitive reaction in liquid hydrogenation of levulinic acid using a hydrogenation catalyst having Fe catalyst (core) / carbon (shell) structure according to an embodiment of the present invention Graph.

Hereinafter, the present invention will be described in more detail by way of examples. These embodiments are only for illustrating the present invention, and the scope of the present invention is not construed as being limited by these embodiments.

Example  One: Fe / C nanoparticle catalyst preparation

Iron (III) acetylacetonate (99.9%) was purchased from Aldrich and N-octyl ether (CH ₃ (CH ₂ ) ₇ O (CH ₂ ) ₇ CH ₃ , 95% Purchased from TCI.

An appropriate amount of iron (III) acetylacetonate was added to a vial containing 10 mL of N-octyl ether. After stirring for 20 minutes at room temperature, ultrasonic waves were applied to the stirred solution for 10 minutes. At this time, the temperature of the solution gradually increased with ultrasound treatment and finally reached about 257 ° C. Acoustic cavitation occurred during ultrasonic treatment, and crystal nucleation of iron (III) acetylacetonate in octyl ether was triggered. As the crystal nuclei grew, α-Fe ₂ O ₃ (hematite) nanoparticles were formed. As the hematite nanoparticles were formed, the carbon species compound generated from the N-octyl ether was incorporated therein. Then, the ultrasound-treated solution (nanoparticle dispersion) was centrifuged and chloroform and ethanol were added several times to remove by-products to separate and obtain α-Fe ₂ O ₃ (hematite) iron oxide nanoparticles.

The obtained? -Fe ₂ O ₃ nanoparticles were annealed at a temperature of 700 ° C. At this time, the carbon species (derived from N-octyl ether) inside the nanoparticle acted as a reducing agent, and Fe ₂ O ₃ was finally reduced to Fe. Further, the carbon paper inside the nanoparticles diffuses to the outside of the particle, and a carbon shell is formed on the surface of the nanoparticle. This finally resulted in a Fe (core) / Carbon (shell) nanoparticle catalyst.

FIG. 1 shows a schematic diagram of a process for producing a nanoparticle catalyst having an Fe catalyst (core) / carbon (shell) structure according to Example 1. FIG.

Meanwhile, in the manufacturing process according to Example 1, intermediate nanoparticles until Fe ₂ O ₃ was finally reduced to Fe through heat treatment were separately recovered and FE-SEM image and HR-TEM The images were taken and the results are shown in FIG.

A (FE-SEM), and B (HR-TEM) of Figure 2 shows the nano-particles _{α-Fe 2 O 3, C} (FE-SEM) and D (HR-TEM) is γ-Fe ₂ O ₃ nanoparticles , And E (FE-SEM) and F (HR-TEM) represent Fe ₃ O ₄ nanoparticles. As a result, the α-Fe ₂ O ₃ of the particles is sequentially reduced, and it can be confirmed that the carbon shell is gradually formed through the HR-TEM image.

FE-SEM images, TEM images and HR-TEM images of the Fe catalyst (core) / carbon (shell) nanoparticle catalyst finally obtained according to Example 1 were taken and the results are shown in Figs. . As shown in FIG. 3C, the nanoparticles were spherical particles having an average diameter of about 300 nm, and it was confirmed that a carbon shell having a thickness of about 20 nm was formed on the surface.

Further, the Fe catalyst (core) / carbon (shell) nanoparticle catalyst finally obtained according to the above Example 1 was subjected to the nitrogen absorption method with BET equipment and the results are shown in FIG. The obtained Fe catalyst (core) / carbon (nanoparticle) catalyst had a specific surface area of 255 m ² / g, a pore volume of 0.14 ml / g and a pore size ) Of 3.7 nm.

Example  2: Cu / C nanoparticle catalyst preparation

The same manufacturing method as in Example 1 was carried out except that copper (II) acetylacetonate was used in place of iron (III) acetylacetonate. This finally resulted in a Cu catalyst (core) / carbon (shell) nanoparticle catalyst.

Experimental Example  One: Fe / C nanoparticle catalyst Levulin mountain  Liquid hydrogenation reaction

0.2 g of the Fe / C nanoparticle catalyst prepared in Example 1 was packed in a tubular reactor (ID = 6.35 mm), and N ₂ gas containing 5% H ₂ was flowed thereinto to raise the temperature to 280 ° C. to activate the catalyst. Thereafter, the reactor was adjusted to a reaction temperature of 170 ° C and a reaction pressure of 5 bar, and a liquid hydrogenation reaction was performed while supplying a 10 wt% levulinic acid aqueous solution (5 g / 45 ml) under a hydrogen gas flow of 130 ml / min. The product analysis was performed at different reaction times (30 minutes, 60 minutes, 120 minutes, 150 minutes, 180 minutes, 240 minutes) and the results are shown in Table 1 and FIG. Furthermore, XRD data of the catalyst before and after the liquid hydrogenation reaction was analyzed, and the results are shown in FIG.

time
(minute) Temperature
(° C) H ₂ pressure
(bar) LA ^* conversion rate
(%) Product selectivity (%) GVL ^* A-lactone ^* others 0 170 5 - - - - 30 14.3 90.2 9.7 - 60 30.2 94.12 5.6 - 120 64.1 95.21 4.7 - 150 79.2 97.85 2.1 - 180 98.21 99.4 0.6 - 240 99.5 98.6 - -

* GVL: Gamma-valerolactone

* A-lactone: Angelica lactone

As shown in Table 1 and FIG. 5, the liquid hydrogenation catalyst according to the present invention showed the highest GVL selectivity (99.4%) at a reaction time of 180 minutes.

Further, as shown in FIG. 6, the XRD data of the catalyst before and after the liquid hydrogenation reaction did not show much change, and it was confirmed that even when the liquid hydrogenation reaction was performed, the catalyst was stably maintained without leaching the active metal Fe.

Experimental Example  2: Levulin mountain  In the liquid hydrogenation reaction Fe / C Confirmation of stability and reusability of nanoparticle catalyst

It was confirmed by the following experiment that the catalytic activity is stably maintained even when the liquid hydrogenation catalyst (Fe / C nanoparticle catalyst) according to the present invention is repeatedly used in the hydrogenation reaction.

0.2 g of the Fe / C nanoparticle catalyst prepared in Example 1 was charged into a batch reactor (100 ml size), and a 10 wt% levulinic acid aqueous solution (5 g / 45 ml) and hydrogen were introduced. The reactor was subjected to a liquid hydrogenation reaction at a reaction temperature of 170 ° C and a reaction pressure of 5 bar and a reaction time of 180 minutes (3 hours). After the reaction was completed, the catalyst was reused as it was and the same experiment as above was repeated. The reaction experiment was repeated 5 times in total.

After each reaction was completed, the product was recovered and analyzed. The results are shown in Table 2 and FIG. 7 below. Further, the XRD data of the catalyst after completion of each reaction was analyzed, and the results are shown in FIG.

Reuse Count Temperature
(° C) H ₂ pressure
(bar) LA ^* conversion rate
(%) Product selectivity (%) GVL ^* A-lactone One 170 5 99.5 99.6 - 2 98.21 98.21 1.5 3 97.58 96.12 4.8 4 97.01 95.21 4.7 5 96.58 94.35 5.61

* GVL: Gamma-valerolactone

* A-lactone: Angelica lactone

As shown in Table 2 and FIG. 7, even when the liquid hydrogenation catalyst according to the present invention was repeatedly used in the liquid hydrogenation reaction, the levulinic acid conversion and the GVL selectivity were all higher than 94%. Accordingly, it was confirmed that the liquid hydrogenation catalyst according to the present invention stably maintains the activity of the catalyst stably in the carbon shell without leaching Fe, which is a catalytically active component.

Further, as shown in FIG. 8, the peak shown in the XRD data of the catalyst is maintained substantially unchanged every time the liquid hydrogenation reaction is repeated, and it is once again confirmed that the catalyst activity and the component are stably maintained even when reused there was.

Experimental Example  3: Cu / C nanoparticle catalyst Levulin mountain  Liquid hydrogenation reaction

Experiments were carried out in the same manner as in Experimental Example 1, except that the hydrogenation was carried out for 4 hours using the Cu / C nanoparticle catalyst prepared in Example 2 instead of the Fe / C nanoparticle catalyst. The results are shown in Table 3 below.

time
(minute) Temperature
(° C) H ₂ pressure
(bar) LA ^* conversion rate
(%) Product selectivity (%) GVL ^* A-lactone ^* others 240 170 5 89.2 97.3 2.6 -

* GVL: Gamma-valerolactone

* A-lactone: Angelica lactone

As shown in Table 3 above, it was also confirmed that the Cu-based liquid phase hydrogenation catalyst according to the present invention exhibits excellent catalytic efficiency of about 90% for the conversion of levulinic acid and about 97% for GVL selectivity at a reaction time of 4 hours .

Claims (19)

Metal catalyst core particles; And a porous shell made of carbon and formed on the surface of the metal catalyst core particle, the method comprising the steps of:
A first step of preparing a mixed solution containing a metal catalyst precursor and a carbon precursor;
A second step of irradiating ultrasonic waves to the mixed solution to form metal oxide particles embedded in carbon paper from the mixed solution; And
And a third step of forming a carbon shell on the particle surface while reducing part or all of the metal oxide through a heat treatment for diffusing the carbon species inside the metal oxide particle to the surface.
The method of claim 1, wherein the metal catalyst precursor is selected from the group consisting of iron (III) acetylacetonate, aluminum acetylacetonate, titanium (IV) oxide acetylacetonate ), Cerium (III) acetylacetonate, hydrate, chromium (III) acetylacetonate, cobalt (II) acetylacetonate, copper (II) acetylacetonate, gallium (III) acetylacetonate, manganese (III) acetylacetonate, iron (II) acetylacetonate, Iron (II) acetylacetonate, magnesium acetylacetonate (hydrate), barium acetylacetonate (hydrate), beryllium acetylacetonate, cadmium (III) acetylacetonate, indium (III) acetylacetonate, cadmium acetylacetonate, cadmium acetylacetonate, cadmium acetylacetonate, cadmium acetylacetonate hydrate, calcium acetylacetonate, (II) acetylacetonate, lithium acetylacetonate, manganese (II) acetylacetonate, lanthanum acetylacetonate, hydrate, lead acetylacetonate, Manganese (II) acetylacetonate, Nickel (II) acetylacetonate, Palladium (II) acetylacetonate, Platinum (II) acetylacetonate ) acetylacetonate, rhodium (III) acetylacetonate, rubidium acetylacetonate, ruthenium (III) acetylacetonate, (III) acetylacetonate, silver acetylacetonate, vanadium (III) acetylacetonate, vanadyl acetylacetonate, yttrium (III) acetylacetonate, wherein the catalyst is selected from the group consisting of acetylacetonate, hydrate, zinc acetylacetonate hydrate, zirconium (IV) acetylacetonate, and mixtures thereof.
The method of claim 1, wherein the carbon precursor is a C4 to C12 alkyl ether.
The method according to claim 1, wherein the heat treatment in the third step is carried out at 300 ° C to 1000 ° C.
Metal catalyst core particles; And
(Core) / carbon (shell) structure, comprising a porous shell of carbon formed on the surface of the metal catalyst core particle.
The liquid hydrogenation catalyst according to claim 5, which is produced by the production method according to any one of claims 1 to 4.
6. The method of claim 5,
Wherein the liquid hydrogenation catalyst is a nanoparticle having an average diameter of 20 nm to 1000 nm.
6. The liquid hydrogenation catalyst according to claim 5, wherein the porous shell has an average thickness of 1 nm to 100 nm.
6. The liquid hydrogenation catalyst according to claim 5, wherein the liquid hydrogenation catalyst has a specific surface area of 50 to 1000 m < ² > / g and a pore volume of 0.05 to 1.0 ml / g.
The liquid hydrogenation catalyst according to claim 5, wherein the metal catalyst is selected from the group consisting of Fe, Fe oxide, Cu, Cu oxide, and mixtures thereof.
6. The liquid hydrogenation catalyst according to claim 5, wherein the metal catalyst is 50 to 99% by weight based on the total weight of the liquid hydrogenation catalyst.
A process for producing a cyclized compound by hydrogenating a solution containing an ester or organic acid of 4 to 6 carbon atoms in the presence of hydrogen,
A production process characterized by using the hydrogenation catalyst produced by the production process according to any one of claims 1 to 4 or the liquid hydrogenation catalyst according to claim 5.
13. The method according to claim 12, wherein the cyclized compound is a lactone compound or a heterocyclic compound containing oxygen.
13. The method of claim 12, wherein the organic acid having 4 to 6 carbon atoms is selected from the group consisting of levulinic acid, succinic acid, fumaric acid, itaconic acid, aspartic acid, Adipic acid and glucaric acid. ≪ RTI ID = 0.0 > 11. < / RTI >
15. The method according to claim 14, wherein the organic acid having 4 to 6 carbon atoms is levulinic acid, and the cyclized compound is gamma-valerolactone.
13. The process according to claim 12, wherein the hydrogenation reaction is carried out at a reaction temperature of 150 to 350 DEG C and a reaction pressure of 1 to 20 bar.
The production method according to claim 12, wherein the solution containing the ester compound of an organic acid or organic acid having 4 to 6 carbon atoms is an aqueous solution.
13. The process according to claim 12, wherein the hydrogenation catalyst is activated by being charged in a reactor and reduced at 50 to 500 DEG C under a flow of a hydrogen-containing reducing gas before supplying the reactant.
Metal catalyst core particles; And a porous shell made of carbon, which is formed on the surface of the metal catalyst core particle, in a process for producing a catalyst having a metal catalyst (core) / carbon (shell) structure and an average diameter of 20 nm to 1000 nm ,
A first step of preparing a mixed solution containing a metal catalyst precursor and a carbon precursor;
A second step of irradiating ultrasonic waves to the mixed solution to form metal oxide particles embedded in carbon paper from the mixed solution; And
And a third step of forming a carbon shell on the particle surface while reducing part or all of the metal oxide through a heat treatment for diffusing the carbon species inside the metal oxide particle to the surface.

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