KR101571319B1 - Sintering-resistant catalyst for water-gas shift reaction, preparing method of the same and water-gas shift method using the same - Google Patents

Abstract

 The present invention provides a catalyst for aqueous gas conversion reaction in which metal nanoparticles are supported in a mesh-type nanostructure carrier, a method for producing the same, and a method for converting a water gas using the same. According to the catalyst for water gas conversion reaction of the present invention, sintering of the metal nanoparticles is suppressed in performing a high temperature water gas conversion reaction, so that the reaction can be stably performed even at a high temperature and the water gas conversion reaction can be performed with high efficiency have.

Description

TECHNICAL FIELD The present invention relates to a catalyst for sintering-inhibiting aqueous gas conversion reaction, a method for producing the same, and a method for converting a water gas into a water-

The present invention relates to a catalyst for sintering-inhibiting aqueous gas conversion reaction, a process for producing the same, and a method for converting a water gas using the same. More specifically, the present invention relates to a catalyst for conversion of a water gas into a metal nano- And a method for producing hydrogen by performing a water-gas shift reaction using the same.

The heterogeneous catalyst used in the catalytic chemical reaction is a catalyst prepared by maximizing the number of catalytic reaction active sites by highly dispersing metal or metal oxide nanoparticles having catalytic activity on a support such as carbon or metal oxide. This heterogeneous catalyst is widely adopted in the commercialization process because of its high reactivity and relatively easy regeneration. However, when a very small nanoparticle catalyst is produced, the nanoparticles become sintered due to a high reaction temperature or a high reaction heat, The number of reaction active sites exposed to the catalyst decreases and, for this reason, the deactivation of the catalytic activity decreases. In addition, the inactivated nanoparticle catalyst having such a large particle size can not be used for a long time in a chemical reaction process because it is virtually impossible to regenerate into small nanoparticles. Therefore, the technique of retarding the inactivation of the catalyst can increase the use time of the heterogeneous catalyst, thereby improving the economical efficiency of the catalyst.

WO 2011055132 A1

The present invention relates to a metal nanoparticle capable of suppressing the increase in size or sintering of metal nanoparticles even under high temperature reaction conditions such as a water gas conversion reaction by supporting metal nanoparticles in a mesh type nanostructure carrier, And a method for producing hydrogen gas stably in a high-temperature aqueous gas reaction using the catalyst.

The present invention provides a catalyst for aqueous gas conversion reaction in which metal nanoparticles are supported in a mesh-type nanostructure carrier.

In one embodiment of the present invention, the metal nanoparticles are selected from the group consisting of platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh), ruthenium (Ru) Or more.

In one embodiment of the present invention, the meshed nanostructure carrier may be at least one selected from the group consisting of aluminum oxide, titanum oxide, silicon oxide, and zirconium oxide.

In one embodiment of the present invention, the meshed nanostructure carrier may have a gamma (?) Crystal structure.

The present invention also provides a process for producing a catalyst for water gas shift reaction comprising the steps of reducing a mixture of a metal precursor and a surfactant and then mixing a precursor of the carrier .

In one embodiment of the present invention, the metal precursor comprises a Pt precursor, a Pd precursor, a Au precursor, a Rh precursor, a ruthenium precursor, and an iridium precursor May be one or more selected from the group.

In one embodiment of the present invention, the metal precursor may be potassium tetrachloroplatinate (II), K ₂ PtCl ₄ .

In one embodiment of the present invention, the surfactant may be an organic surfactant including an aqueous solution of tetradecyltrimethylammonium bromide.

In one embodiment of the present invention, the reduction may be performed using a reducing agent including an aqueous solution of sodium borohydride (NaBH ₄ ).

In one embodiment of the present invention, the precursor of the support may be a metal oxide precursor.

In one embodiment of the present invention, the precursor of the support may be an alumina precursor.

In one embodiment of the present invention, the precursor of the support may be aluminum tert-butoxide.

In one embodiment of the present invention, the precursor of the carrier may be a solution in which aluminum tert-butoxide is dissolved in ethanol.

In one embodiment of the present invention, the method may further include stirring the mixture obtained in the mixing step at room temperature for 24 hours or more.

In one embodiment of the present invention, the method may further include drying the mixture obtained at the stirring step at 70 to 95 ^° C for at least 24 hours, and calcining at 400 to 600 ^° C for 6 to 10 hours.

The present invention also provides a water gas conversion reaction method for producing hydrogen from a mixture of carbon monoxide and water using the above-mentioned catalyst for aqueous gas conversion reaction.

According to the catalyst for water gas conversion reaction of the present invention, sintering of the metal nanoparticles is suppressed in performing a high temperature water gas conversion reaction, so that the reaction can be stably performed even at a high temperature and the water gas conversion reaction can be performed with high efficiency have.

1 is a schematic view showing a reactor apparatus for a water gas shift reaction using a catalyst for water gas shift reaction according to an embodiment of the present invention.
2 is a TEM photograph of an alumina supported metal catalyst according to an embodiment of the present invention.
3 is an XRD result of an alumina supported metal catalyst according to an embodiment of the present invention.
4 is a TEM photograph of an alumina supported metal catalyst according to a comparative example of the present invention.
5 shows XRD results of an alumina supported metal catalyst according to a comparative example of the present invention.
6 is a TEM photograph of an alumina supported metal catalyst according to a comparative example of the present invention.
7 is a TEM photograph of an alumina supported metal catalyst after a water gas shift reaction according to an embodiment of the present invention.
8 is a TEM photograph of an alumina supported metal catalyst after a water gas shift reaction according to a comparative example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail in order to facilitate the present invention by those skilled in the art.

The term 'water gas conversion reaction' as used in the present invention means a reaction for producing hydrogen gas and carbon dioxide from carbon monoxide and water.

The present invention provides a catalyst for aqueous gas conversion reaction in which metal nanoparticles are supported in a mesh-type nanostructure carrier.

In the present invention, the metal nanoparticles may be at least one selected from the group consisting of platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh), ruthenium (Ru), and iridium (Ir). Preferably platinum.

In the present invention, the mesa-shaped nanostructure carrier supports the metal nanoparticles in the mesa-shaped nanostructure. In the conventional carrier, the metal nanoparticles rise on the carrier, but in the present invention, the metal nanoparticles enter the carrier due to the mesh structure. In addition, the conventional core-shell type carrier may be limited in its use due to a problem of mass transfer in the shell, but the mesh type nanosized carrier of the present invention has an advantage that mass transfer is easy.

The mesoporous nanostructured carrier may be at least one selected from the group consisting of aluminum oxide, titanum oxide, silicon oxide, and zirconium oxide. Preferably alumina.

The mesa-shaped nanostructure carrier may have a crystal lattice structure having a gamma (?) Crystal structure. When the carrier has a gamma ([gamma]) crystal structure, the metal nanoparticles have excellent ability to be coated.

The present invention also provides a process for producing a catalyst for aqueous gas conversion reaction comprising the step of reducing a mixture of a metal precursor and a surfactant and then mixing a precursor of the carrier .

The metal precursor refers to a precursor of metal nanoparticles to be supported in a carrier. The metal precursor may be at least one selected from the group consisting of a platinum (Pt) precursor, a palladium (Pd) precursor, a gold (Au) precursor, a rhodium precursor, a ruthenium (Ru) precursor, and an iridium (Ir) Preferably a platinum precursor. For example, as a platinum precursor, platinum tetrachloroplatinate (K ₂ PtCl ₄ ), platinum chlorate (H ₂ PtCl ₆ or H ₂ PtCl ₆ .xH ₂ O), platinum nitrate (Pt (NO ₃ ) ₄ ), Platinum acetate (Pt (CH ₃ COO) ₂ ), and the like.

The surfactant is not particularly limited, but may be an organic surfactant including an aqueous solution of tetradecyltrimethylammonium bromide.

The metal precursor and the surfactant are mixed to prepare a mixture, which is then reduced. In this case, a known reducing agent may be used for the reduction. For example, an aqueous solution of sodium borohydride (NaBH ₄ ) may be used as the reducing agent, but the present invention is not limited thereto.

The precursor of the support may be a metal oxide precursor and may be a precursor of a metal oxide selected from the group consisting of an aluminum oxide precursor, a titanum oxide precursor, a silicon oxide precursor, and a zirconium oxide precursor . Preferably, the precursor of the support may be an alumina precursor. More specifically, the precursor of the carrier may be aluminum tert-butoxide, and it is preferable to mix a solution in which aluminum tert-butoxide is dissolved in ethanol.

After the mixture of the metal precursor and the surfactant is reduced and the precursor of the carrier is mixed, the resulting mixture is stirred for 24 hours or more, specifically 24 to 96 hours at room temperature. In the present invention, the room temperature means 20 to 28 ^° C, more specifically, 24 to 28 ^° C.

After the stirring, the resulting mixture is dried at 70 to 95 ^° C for at least 24 hours and calcined at 400 to 600 ^° C for 6 to 10 hours. Preferably at 85 to 95 ^° C for 24 to 96 hours and calcined at 450 to 550 ^° C for 6 to 7 hours.

The chemical reaction using the catalyst for water gas shift reaction according to the present invention is not particularly limited, but a water gas conversion reaction for producing hydrogen from a mixture of carbon monoxide and water can be carried out.

The present invention will be described in more detail with reference to the following specific examples and experimental examples. The following Examples and Experimental Examples are provided only to aid understanding of the present invention, and the scope and scope of the present invention are not limited thereto.

[Example 1]

A platinum nanoparticle catalyst supported on a meshed alumina support was prepared using a metal precursor, a surfactant, a reducing agent, and a solvent.

A solution of 0.0208 g of potassium tetrachloroplatinate (K ₂ PtCl ₄ ) and 1.682 g of tetradecyltrimethylammonium bromide (TTAB) was dissolved in 47 mL of deionized water, And stirred at 50 ^° C for 10 minutes. 0.0508 g of sodium borohydride (NaBH ₄ ) was dissolved in 3 mL of ion-exchanged water cooled at 0 ^° C, and this aqueous solution of NaBH ₄ was added to the mixed solution of K ₂ PtCl ₄ and TTAB I put it fast. The mixed solution was stirred at 50 ^° C. for 15 hours, then 0.6 mL of aluminum tert-butoxide solution dissolved in 24 mL of ethanol heated at 80 ^° C. was mixed and stirred at room temperature for 24 hours . Thereafter, ethanol was added and the product was precipitated with a centrifuge, and the obtained product was dried in a vacuum of 90 ^° C for 24 hours. The dried product was calcined at 500 ^o C in air for 6 hours.

[Example 2]

A water gas conversion reaction was carried out using the catalyst prepared in Example 1 above.

The water gas shift reaction was carried out at atmospheric pressure using a reactor as in FIG. 1, which included a cylindrical fixed bed reactor (inner diameter 7.8 mm). 0.2 g of the catalyst prepared in Example 1 was charged into the reactor 6 and heated. The catalyst was reduced for 3 hours while flowing a total of 75 mL / min of 10% hydrogen gas diluted with nitrogen gas at 350 ^o C. Nitrogen gas was then flowed for 60 minutes and the reactor temperature was cooled to 200 ^° C. The gas hourly space velocity (GHSV) was fixed at 22500 h ^-1 and the reaction was carried out while flowing 2.24 mol% of carbon monoxide gas diluted with nitrogen gas. After the reaction, the product was cooled with a cooler (7) and analyzed by a gas chromatograph (8).

[Comparative Example 1]

A platinum nanoparticle catalyst supported on an alumina support was prepared using a metal precursor, a surfactant, a reducing agent, a solvent, and a commercial alumina carrier.

A solution of 0.0208 g of potassium tetrachloroplatinate (K ₂ PtCl ₄ ) and 1.682 g of tetradecyltrimethylammonium bromide (TTAB) was dissolved in 47 mL of deionized water, And stirred at 50 ^° C for 10 minutes. 0.0508 g of sodium borohydride (NaBH ₄ ) was dissolved in 3 mL of ion-exchanged water cooled at 0 ^° C, and this aqueous solution of NaBH ₄ was added to the mixed solution of K ₂ PtCl ₄ and TTAB Quickly inject. The mixed solution was stirred at 50 ^° C. for 15 hours, 0.13025 g of γ-alumina was added to the mixed solution, and the mixture was stirred at room temperature for 24 hours. Thereafter, ethanol was added and the product was precipitated with a centrifuge, and the obtained product was dried in a vacuum of 90 ^° C for 24 hours. The dried product was calcined at 500 ^o C in air for 6 hours.

[Comparative Example 2]

An alumina support free of platinum was prepared using an aluminum precursor, a surfactant, a solvent, and the like.

4.2903 g of TTAB was mixed with 1.5 mL of aluminum tert-butoxide solution dissolved in 60 mL of ethanol heated to 80 ^° C and stirred at room temperature for 24 hours. Thereafter, ethanol was added and the product was precipitated with a centrifuge, and the obtained product was dried in a vacuum of 90 ^° C for 24 hours. The dried product was calcined at 500 ^o C in air for 6 hours.

[Experimental Example 1] TEM photograph and XRD analysis

The catalysts prepared in Example 1 and Comparative Examples 1 and 2 were analyzed by TEM and XRD. TEM and XRD of Example 1 are shown in FIGS. 2 and 3, TEM and XRD of Comparative Example 1 are shown in FIG. 4 and FIG. 5, respectively, and a TEM photograph of Comparative Example 2 is shown in FIG.

From the TEM photograph of the catalyst, it was confirmed that the particle size was about 10 nm in platinum particle in Example 1 shown in FIG. 2 and Comparative Example 1 shown in FIG. The results of XRD show that the alumina support of Example 1 shown in FIG. 3 and Comparative Example 1 shown in FIG. 5 both have a? -Alumina crystal structure. When the platinum precursor was excluded from the precursor composition as in Comparative Example 2, a mesh-like alumina support was not obtained as shown in FIG. 6, and it was confirmed that the mesh-like support was obtained only when the platinum precursor was mixed with another precursor mixture .

[Experimental Example 2]

Using the catalyst prepared in Example 1 and Comparative Example 1, a water gas conversion reaction was carried out in the same manner as in Example 2, and CO conversion was measured according to the reaction temperature. The experimental results are shown in Table 1 below.

Reaction temperature 250 ℃ 300 ° C 350 ℃ 400 ° C CO conversion rate Example 1 2.01% 13.55% 49.84% 91.26% Comparative Example 1 0.17% 4.24% 22.23% 58.34%

As can be seen from the above Table 1, it can be seen that the reaction activity of the catalyst prepared in Example 1 is higher than that of the catalyst prepared in Comparative Example 1.

[Experimental Example 3]

The particle size of the catalyst after the water gas shift reaction according to Example 2 was analyzed by TEM. The results of the catalyst prepared in Example 1 and the catalyst prepared in Comparative Example 1 are shown in Fig. 7 and Fig. 8, respectively. The catalyst prepared according to Example 1 maintained a particle size of approximately 10 nm as shown in FIG. 7, but the catalyst prepared according to Comparative Example 1 had irregular particle sizes due to severe sintering as shown in FIG. 8 And a particle size of about 40 nm was generated. As a result, it was confirmed that the catalytic activity point was sharply reduced.

1: hydrogen gas cylinder
2: Carbon monoxide gas cylinder
3: Nitrogen gas cylinder
4: Mixer
5: water mixer
6: Reactor
7: Cooler
8: Gas chromatographic apparatus

Claims (16)

As a catalyst for water gas shift reaction for producing hydrogen gas and carbon dioxide from carbon monoxide and water,
Wherein the catalyst comprises at least one metal nanoparticle selected from the group consisting of Pt, Pd, Au, Rh, Ru and Ir, However,
Wherein the nanostructured carrier has a gamma (?) Crystal structure, and the nanostructures constituting the carrier are irregularly formed in a thicket shape. The method according to claim 1,
Wherein the nanostructured carrier is formed from a precursor of a carrier that is at least one selected from the group consisting of an aluminum oxide precursor, a titanium oxide precursor, a silicon oxide precursor, and a zirconium oxide precursor. Catalyst for conversion reaction. 3. The method of claim 2,
Wherein the precursor of the support is a solution in which aluminum tert-butoxide is dissolved. delete A process for producing a catalyst for aqueous gas conversion reaction according to claim 1,
Mixing a precursor solution of the carrier with a mixture of a metal precursor and a surfactant after stirring and reducing the mixture. 6. The method of claim 5,
Wherein the metal precursor is at least one selected from the group consisting of a platinum (Pt) precursor, a palladium (Pd) precursor, a gold (Au) precursor, a rhodium precursor, a ruthenium (Ru) precursor, and an iridium (Ir) precursor (2). 6. The method of claim 5,
Wherein the metal precursor is potassium tetrachloroplatinate (II) (K ₂ PtCl ₄ ). 6. The method of claim 5,
Wherein the surfactant is an organic surfactant including an aqueous solution of tetradecyltrimethylammonium bromide. 6. The method of claim 5,
Wherein the reduction is performed using a reducing agent comprising an aqueous solution of sodium borohydride (NaBH ₄ ). 6. The method of claim 5,
Wherein the precursor of the support is a metal oxide precursor. 6. The method of claim 5,
Wherein the precursor of the support is an alumina precursor. 6. The method of claim 5,
Wherein the precursor of the support is aluminum tert-butoxide. 13. The method of claim 12,
Wherein the precursor solution of the carrier is a solution in which aluminum tert-butoxide is dissolved in ethanol. 6. The method of claim 5,
Further comprising stirring the mixture obtained in the mixing step at room temperature for 24 hours or more. 15. The method of claim 14,
Drying the mixture obtained in the step of agitating at 70 to 95 ^° C for at least 24 hours and calcining at 400 to 600 ^° C for 6 to 10 hours. A method for converting hydrogen gas into hydrogen from a mixture of carbon monoxide and water using the catalyst for aqueous gas conversion reaction according to any one of claims 1 to 3.

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