KR102152596B1 - A method for preparing an electrode catalyst for a fuel cell having sufur resistance and carbon coking resistance and a dry reforming method using the catalyst - Google Patents

Abstract

A method of manufacturing an electrode catalyst for a fuel cell, comprising: doping and substituting a part of Ti in a perovskite material with a noble metal or a transition metal; And reducing the doped-substituted perovskite material at 650° C. or higher for 10 hours or longer. A method of manufacturing an electrode catalyst for a fuel cell is disclosed.

Description

A method of manufacturing an electrode catalyst for fuel cells having sulfur resistance and carbon deposition resistance, and a dry reforming method of the catalyst {A METHOD FOR PREPARING AN ELECTRODE CATALYST FOR A FUEL CELL HAVING SUFUR RESISTANCE AND CARBON COKING RESISTANCE AND A DRY REFORMING METHOD USING THE CATALYST}

The present invention relates to a method for preparing an electrode catalyst for a fuel cell and a method for dry reforming the catalyst. More specifically, the present invention relates to a method of manufacturing an electrode catalyst for a fuel cell having sulfur resistance and carbon deposition resistance, and a dry reforming method of the catalyst.

High-temperature fuel cells such as Solid Oxide Fuel Cell (SOFC) and Molten Carbonate Fuel Cell (MCFC) are methane (CH ₄₎ made from agricultural, general and food waste, manure, and plant materials. ) As a main component of CO ₂ neutral alternative fuel such as biogas, which can be efficiently converted into electric power, thereby realizing clean power generation.However, if such alternative fuel is supplied directly to fuel cells, fuel The performance of the fuel cell may be greatly degraded due to impurities contained in the fuel cell, and in some cases, carbon deposition may occur in the fuel cell, thereby greatly reducing the performance of the fuel cell.

Due to the characteristics of the alternative fuel, the concentration of impurities and the composition of the fuel change with time and season, and when the alternative fuel is directly applied to a high-temperature fuel cell, it is necessary to develop a cell component that is highly resistant to impurities and carbon deposition. In addition, catalysts and batteries having the above characteristics must be manufactured economically. This patent is intended to propose a dry reforming method having sulfur resistance and carbon deposition resistance by using a material capable of corresponding to the above use as a fuel cell electrode and a catalyst.

Korean Patent Publication No. 10-2013-0133251

An object of the present invention is to prepare a catalyst for a fuel cell having excellent sulfur resistance and carbon deposition resistance, and to effectively dry-reform methane using such a catalyst.

In an exemplary embodiment of the present invention, a method of manufacturing an electrode catalyst for a fuel cell includes the steps of doping and substituting a part of Ti with a noble metal or a transition metal among the perovskite materials represented by the following Formula 1; And reducing the doped-substituted perovskite material at 650° C. or higher for 10 hours or longer. It provides a method of manufacturing an electrode catalyst for a fuel cell comprising a.

[Formula 1]

Sr _1-y Y _y TiO _3-z

In Formula 1, 0<y<1 and 0<z<1.

In an exemplary embodiment of the present invention, a method for improving sulfur resistance and carbon deposition resistance of an electrode catalyst for a fuel cell, comprising: doping and substituting a portion of Ti in the perovskite material represented by Formula 1 with a noble metal or a transition metal; And reducing the doped-substituted perovskite material at 650° C. or higher for 10 hours or longer. It provides a method of improving sulfur resistance and carbon deposition resistance of an electrode catalyst for a fuel cell comprising.

An exemplary embodiment of the present invention provides an electrode catalyst for a fuel cell, represented by the following formula (2), wherein M is eluted on a perovskite material.

[Formula 2]

Sr _1-y Y _y Ti _1-x M _x O _3-z

In Formula 2, 0<x<1, 0<y<1, and 0<z<1, and M is a noble metal or a transition metal.

An exemplary embodiment of the present invention provides a methane dry reforming method using an electrode catalyst for a fuel cell.

According to the present invention, a perovskite material doped and substituted with a noble metal or a transition metal noble metal or a transition metal is reduced for a long time (more than 10 hours) at a high temperature (650°C or higher), thereby improving sulfur resistance and carbon deposition resistance. An electrode catalyst can be prepared.

In addition, the catalyst is reduced in a hydrogen atmosphere with an inert gas such as nitrogen (N ₂ ), helium (He) or argon (Ar), thereby eluting the doped-substituted noble metal or transition metal on the surface of the perovskite material ( exsolution) to have higher catalytic activity.

In addition, since the electrode catalyst for a fuel cell according to the present invention is prepared through the Petchney method, it is possible to manufacture a material having a relatively large specific surface area and high purity compared to the solid state reaction, and by controlling the gelation reaction rate Surface characteristics such as size can be adjusted.

1 is Ru, Rh, a noble metal or a transition metal (M), such as Ni doped _{SYT (Sr 0 98 Y 0 .02} Ti 1-x M x O 3.) Sol of the perovskite catalyst-gel (sol -gel) method based on the Pechini method and the outline of the apparatus for evaluating the methane dry reforming (Dry Reforming of Methane, DRM) performance of the catalyst and the performance evaluation conditions are shown.
FIG. 2 shows that a metal (transition metal or precious metal) as an active material is supported on a SrYTiO ₃ type perovskite by a conventional impregnation method ( It shows that a part of Ti at the B site of the ABO3 type perovskite is substituted with metal to be doped into the lattice inside the perovskite structure.
3 is an XRD analysis of a crystal phase before and after dry modification of a material doped with 5, 10 and 15 mol% substitution of Ti of SYT and Ru synthesized by the method proposed in the present invention, respectively.
FIG. 4 is a comparison of dry reforming performance and long-term performance stability by temperature according to the presence or absence of 12.5 ppm H ₂ S for the SYTRu5 catalyst substituted with 5 mol% of Ru by reduction treatment at 900°C for 4 hours with the conversion rate of methane. .
5 is a diagram showing the reaction activity by temperature and long-term stability at 750°C without H ₂ S of a catalyst doped with 10 mol% Ru (SYTRu10) and a supported catalyst (Ru 10 loaded SYT) as a methane conversion rate. .
6 is methane from 600° C. to 900° C. of a Ru 10 loaded SYT catalyst in which pure SYT and Ru are doped with 2, 5, 10 mol% of Ti, respectively, and Ru 10 loaded SYT catalyst in the same amount as SYTRu2, 5, 10 and SYTRu10 This is a picture showing the carbon dioxide conversion rate.
7 is a diagram showing the methane conversion rate of the catalyst pretreated for 4, 12, and 24 hours in a 900°C 20% hydrogen atmosphere of the SYTRu5 catalyst at 600°C to 900°C, respectively.
8 is a diagram showing methane conversion rates at 900°C and 750°C, respectively, while supplying 100 ppm of H2S following FIG. 7.
9 shows the methane conversion rate in the presence of 100 ppm of H ₂ S at a reaction temperature of 900° C. after reduction treatment at 900° C. for 12 hours and 24 hours, respectively, of a SYTRh5 catalyst in which 5 mol% of rhodium (Rh) is substituted in the place of Ti. will be.
FIG. 10 is a diagram for evaluating the methane dry reforming performance of catalysts subjected to hydrogen pretreatment at 900° C. for 24 hours at 900° C. of SYTRu5, SYTRh5, and SYTNi5 catalysts each substituted with 5 mol% of Ru, Rh and Ni in the presence of 100 ppm H ₂ S. to be.
11 shows the results of methane dry reforming in the presence of 100 ppm of H ₂ S at 900° C. after heating in an N ₂ atmosphere of a pure SYT catalyst.
12 shows a TEM image and a Fast Fourier Transform (FFT) pattern before and after reduction treatment at 900° C. for 24 hours of a SYTRh10 catalyst.
13 shows SEM and TEM images of SYT (pure), SYTRu10 (substituted), and Ru 10 loaded SYT (supported) catalysts.
14 shows a TEM image of a SYTRu5 catalyst and a catalyst evaluated for dry reforming in the presence of H ₂ S after pretreatment at 900° C. for 4 hours and 24 hours, respectively.
FIG. 15 is a diagram of elemental image mapping using TEM after methane dry reforming reaction of SYTRu10 (substitution) and Ru 10 loaded SYT (supported) catalysts.
FIG. 16 shows changes in surface composition analyzed by SEM/EDX (SEM Energy Dispersive Spectrometer) method before and after methane dry reaction of SYT and SYTRu catalysts.
17 is a diagram showing whether a dry reaction of methane in the presence of H ₂ S when a perovskite catalyst doped with a catalytically active metal is subjected to reduction treatment.

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

The embodiments of the present invention disclosed in the text are exemplified for purposes of explanation only, and the embodiments of the present invention may be implemented in various forms and should not be construed as being limited to the embodiments described in the text. .

The present invention is not intended to limit the present invention to a specific disclosed form, as various changes can be added and various forms may be added, and all changes, equivalents or substitutes included in the spirit and scope of the present invention It should be understood to include.

In the present specification, bio-gas is a gaseous fuel that can produce biomass such as sewage sludge and food waste through anaerobic digester, gasification, and pyrolysis. to be. Such biogas contains methane (55-70%) and carbon dioxide (30-45%) as main components, and contains impurities such as sulfur (S).

In the present specification, a dry reforming reaction refers to a reaction of reacting carbon dioxide and methane to produce carbon monoxide and hydrogen. The dry reforming reaction is useful in terms of reuse of carbon dioxide, and it is an endothermic reaction, so the reaction is low. For reference, Reaction Formula 1 below is a reaction formula of a dry reforming reaction of carbon dioxide.

[Scheme 1]

_{CH 4 + CO 2 ↔2CO + 2H} 2 (△ 298K = +247 kJ / mol)

In the present specification, a homogenous catalyst refers to a catalyst capable of maintaining a single phase by including an active material substituted in a material lattice.

In the present specification, the long-term stability of the catalyst means the conversion rate of the catalyst or the hydrogen selectivity (the molar ratio of the generated hydrogen to the fuel consumed in the reaction), that is, a property capable of maintaining a high catalytic activity over a required level for a long time . Therefore, improving the long-term stability of the catalyst means improving the life of the catalyst.

In the present specification, the Pechini method broadly refers to a chelating action between an acid contained in a polymer resin (citric acid) and cations dissolved in a solvent, and a metal-chelating complex and polyhydroxyalcohol (titanium isopro). It refers to a powder synthesis method in which a chemically homogeneous and stable precursor can be obtained by the action of polymerization between foxsides) causing the dispersion of cations.

Method for producing catalyst

In exemplary embodiments of the present invention, a method of manufacturing an electrode catalyst for a fuel cell, comprising: doping and substituting a part of Ti with a noble metal or a transition metal among the perovskite materials represented by the following Formula 1; And reducing the doped-substituted perovskite material at 650° C. or higher for 10 hours or longer. It provides a method of manufacturing an electrode catalyst for a fuel cell comprising a.

[Formula 1]

Sr _1-y Y _y TiO _3-z

In Formula 1, 0<y<1 and 0<z<1.

More specifically, in order to doping-substitute part of the B site (Ti) with a noble metal or transition metal in the perovskite material, distilled water or deionized water (DI water) is used as a solvent. Among dry catalyst manufacturing methods, it may be carried out through the Pechini method.

That is, referring to the catalyst synthesis procedure of FIG. 1, in one embodiment, yttrium nitrate ((Y(NO ₃ ) ₃ H ₂ ), Aldrich) and strontium nitrate (Sr(NO ₃ ) ₃ H ₂ ), Aldrich) and The first solution may be prepared by dissolving the same compound in distilled or deionized water (DI water). A second solution may be prepared by sufficiently dissolving a titanium compound (Ti[OCH(CH ₃ ) ₂ ] ₄ ) and citric acid in ethylene glycol. Ruthenium chloride hydrate (RuCl ₃ xH ₂ O), rhodium trichloride (Rhodium chloride hydrate (RhCl ₃ xH ₂ O)), or Nickel nitrate hexahydrate (Ni(NO ₃ ) ₃ 6H ₂ O)), A third solution may be prepared by dissolving a precursor in distilled water or DI water. At this time, each compound of noble metal or transition metal such as yttrium (Y), strontium (Sr), titanium (Ti) and Ru, Rh or Ni is dissolved in distilled or deionized water (DI water) instead of ethanol as in the prior art, It is possible to minimize the content of impurities in the produced catalyst.

The first solution, the second solution, and the third solution thus prepared are mixed together, sufficiently stirred at about 80° C., dried at about 110° C., and then calcined at a temperature above about 300° C. and below 450° C. I can. The calcination process may be performed more than once, for example, by performing a first calcination process at about 300°C and a second calcination process at about 450°C. Accordingly, it is possible to effectively remove organic substances that may be generated during catalyst preparation. The calcined compounds may be grinded and finally further calcined at about 650°C.

The above-described processes are the Pechini method using distilled water or deionized water (DI water) as a solvent.

Referring to FIG. 2, the catalyst of the present invention is a SrYTiO ₃ type perovskite in which the active material metal (transition metal or precious metal) is supported by the conventional impregnation method. Unlike loading on the perovskite, a part of Ti at the B site of the ABO ₃ type perovskite is replaced with metal so that it is doped into the lattice inside the perovskite structure. I did it.

Thereafter, the prepared catalyst is subjected to activation treatment, that is, reduction.

In the present invention, the most different content from the existing catalyst activation treatment method is to increase the pretreatment (reduction) temperature and time for enhancing catalyst activity. In order to make the metal catalytically active material supported on a general metal oxide support into a metallic state, reduction is performed for 2-4 hours using hydrogen at a temperature between 600-700°C. In order to improve the sulfur resistance and carbon deposition resistance of the catalyst, the present inventors performed a reduction reaction for 10 hours or more at a temperature of 650° C. or higher, different from the conventional reduction treatment temperature. For example, the reduction temperature may be 650°C or higher, 700°C or higher, 750°C or higher, 800°C or higher, 850°C or higher, or 900°C or higher. In addition, the reduction time may be 10 hours or more, 12 hours or more, 14 hours or more, 16 hours or more, 18 hours or more, 20 hours or more, 22 hours or more, or 24 hours or more.

In exemplary embodiments, the noble metal or transition metal may be, for example, one or more of noble metals Pt, Pb, Pd, Ir, and Pr, and may be one or more of transition metals Cu, Fe, Co, and Mn, preferably May be at least one selected from the group consisting of Ru, Rh and Ni.

In example embodiments, the reducing may be performed using an inert gas in a hydrogen atmosphere. In exemplary embodiments, the inert gas may be at least one selected from the group consisting of nitrogen, helium, and argon.

In example embodiments, the reducing step may be for exsolution of the noble metal or transition metal on the perovskite material. By eluting the noble metal or the transition metal through the reducing step, the noble metal or the transition metal may perform a conversion catalyst function that aids in the electrochemical oxidation of hydrogen in place of the existing perovskite material.

Conventional pretreatment with hydrogen exposes a lot of Ni to the surface, and Ni, known to have poor carbon deposition, sulfur poisoning, and thermal durability, is easily poisoned and thermally agglomerated.Therefore, there is no need for a hydrogen treatment process for pretreatment, and no precious metal is used. It has been argued that it can achieve dry reforming performance.

However, in the case of the present invention, when a nano-sized catalytically active material is reduced to the surface in a hydrogen atmosphere, and the doped noble metal or transition metal is eluted, the particle size can be smaller than that of the support and evenly distributed on the surface. Compared to the supported catalyst, since it is substituted on the support lattice, the bond is strong (strongly anchoring).It is considered to have economical efficiency as it can use less durable and expensive catalyst materials other than those having carbon deposition and sulfur resistance described above. .

More specifically, referring to FIG. 17, a perovskite material having an ABO ₃ structure is not basically a complete oxide, but a material depleted of oxygen (oxygen vacancy or oxygen defects), and has a cubic structure or an orthorhombic structure. As a material having an orthorhombic structure, it is widely applied and studied in fuel cell electrodes, high-temperature superconductors, optoelectronic materials such as sunlight, and catalysts.

Substituting-doped catalytic material at the B site of this material causes metal particles to exist in the bulk lattice. The particles present in this way are eluted to the surface of the material due to the difference between oxygen and hydrogen in the reducing atmosphere by hydrogen, and oxygen vacancies (defects) are created more inside, and this is the oxidation-reduction characteristic ( redox property). The metal material that has moved to the surface in this way exists on the surface in the size of several nano-sized nano dots.

Based on the known Mars-Van Krevelen mechanism, CH ₄ , CO ₂ , H ₂ S are adsorbed on metal particles protruding to the surface, forming C _(ads) , CO _(ads) and H ₂ S _(ads) on the surface. and this metal and the support chain perovskite moves (migration) to the surface (interface) of the site of free radicals generated by the oxygen vacancy (active oxygen, O ^-) in combination with the desorption by the CO and SO _2, and the reaction It is thought to generate H ₂ and the like.

In exemplary embodiments of the present invention, as a method of improving sulfur resistance and carbon deposition resistance of an electrode catalyst for a fuel cell, a step of doping and substituting a part of Ti in a perovskite material represented by the following Formula 1 with a noble metal or a transition metal ; And reducing the doped-substituted perovskite material at 650° C. or higher for 10 hours or longer. It provides a method of improving sulfur resistance and carbon deposition resistance of an electrode catalyst for a fuel cell comprising.

[Formula 1]

Sr _1-y Y _y TiO _3-z

In Formula 1, 0<y<1 and 0<z<1.

catalyst

In exemplary embodiments of the present invention, an electrode catalyst for a fuel cell is provided as an electrode catalyst for a fuel cell, represented by Formula 2 below, and wherein M is eluted on a perovskite material.

[Formula 2]

Sr _1-y Y _y Ti _1-x M _x O _3-z

In Formula 2, 0<x<1, 0<y<1, and 0<z<1, and M is a noble metal or a transition metal.

The catalyst is represented by Chemical Formula 2, in which a part of strontium (Sr) of a perovskite material is doped-substituted with yttrium (Y) and a part of titanium (Ti) is doped-substituted with a noble metal or transition metal. That is, the catalyst is a material in which a part of the A site (Sr) and a part of the B site (Ti) in a perovskite material having a structure of ABO ₃ are different from each other (a noble metal or transition at the A site and the B site Metal), it is possible to maintain the perovskite structure as a basic structure.

Therefore, unlike conventional catalysts, which are generally so-called heterogeneous catalysts composed of two or more phases prepared by heat treatment of an active material on a support, the catalyst is a single phase homogeneous catalyst. Can be Therefore, the catalyst can be prepared through a minimized synthesis process, and is more useful in terms of process efficiency and economy than conventional catalysts.

In addition, yttrium (Y) substituted for the strontium site (site A of the perovskite structure) may provide improved electrical conductivity to the catalyst. Specifically, it can achieve the purpose of using it as an anode electrode material for SOFC.

Moreover, since the perovskite catalyst having the structure of ABO ₃ is inherently excellent in resistance to sulfur (S) and carbon (C), the catalyst can have high catalytic activity for the biogas reforming reaction, and It may have high resistance to carbon deposition and/or catalyst poisoning.

The eluted M may exist on the catalyst in the form of thermal sitering particles, and may have a size of 10 nm or less. For example, the size of the particles may be 10 nm or less, 9 nm or less, 8 nm, 7 nm, 6 nm or 5 nm or less. As the particle size decreases, the specific surface area increases even in the same amount, and the catalytic activity sites exposed on the surface increase, thereby enhancing the activity.

In addition, as the circumference of several smaller circles than one large circle (arc) even with the same circle area, the boundary where the particles exposed on the surface meet the support SYT increases, resulting in catalytic reaction. Can increase.

In exemplary embodiments, when considering all of the maintenance of a single phase of the catalyst, prevention of carbon deposition and/or poisoning of the catalyst, maintenance of the activity of the catalyst and improved electrical conductivity, substitution of the titanium site (B site of the perovskite structure) In the case of the amount of M (noble metal or transition metal such as Ru), it is advantageous in terms of cost and activity to expose a large amount to the surface by putting a relatively small amount. In addition, the amount of yttrium (Y) substituted in the strontium site (site A of the perovskite structure), that is, in the above formula 2, y is greater than 0 and less than 0.08 (0<y≦0.08), especially y is 0.08. It may be desirable.

In exemplary embodiments, the fuel cell electrode catalyst may be used for methane dry reforming.

In exemplary embodiments of the present invention, a methane dry reforming method using the aforementioned electrode catalyst for a fuel cell is provided.

The present invention will be described in more detail through the following implementation. However, the examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example

Yttrium nitrate (Y(NO ₃ ) ₃ ·H ₂ O (Aldrich)) and strontium nitrate (Sr(NO ₃ ) ₃ ·H ₂ O (Aldrich)) were simultaneously dissolved in DI water. In order to stabilize titanium sopropoxide (Ti(OCH(CH ₃ ) ₂ ) ₄ ) (Junsei), ethylene glycol (99.9%) is slowly added and dissolved while stirring, and then ruthenium trichloride suitable for the doping amount ( After adding Cl ₃ Ru·xH ₂ O) (Aldrich), citric acid was dissolved together for dispersion.

At this time, the amount of citric acid was the same as the number of moles of the metal precursor to be added for synthesis. The solutions are mixed together at 80° C., stirred in a water bath atmosphere, and then the precipitate is dried at 110° C. for 24 hours. Then, the first and second calcinations were performed at 300° C. and 450° C. for 2 hours in an air atmosphere to remove residual precursors and impurities, and the obtained catalyst particles were calcined at 650° C. for 10 hours.

Experimental example

Synthesized catalyst observation

3 is an XRD analysis of a crystal phase before and after dry modification of a material synthesized by substituting 5, 10 and 15 mol% of Ti with Ru by the method proposed in the present invention. Referring to Figure 3, it can be seen that the catalysts doped with Ru before the reaction test also show the same form as the crystal of SYT, and even after the reaction experiment, a slight impurity peak corresponding to titania (TiO ₂ ), etc., is observed, but the crystal phase It was confirmed that this was kept stably.

Evaluation of catalyst performance with or without sulfur

FIG. 4 is a comparison of dry reforming performance and long-term performance stability by temperature according to the presence or absence of 12.5 ppm H ₂ S for the SYTRu5 catalyst substituted with 5 mol% of Ru by reduction treatment at 900°C for 4 hours with the conversion rate of methane. . According to the existing method, in the presence of a low concentration of 12.5 ppm H ₂ S, the conversion rate is maintained similarly above 650°C, but the activity rapidly decreases at a temperature below 750°C, and the activity is not maintained stably even when the temperature is raised again. .

Evaluation of activity and long-term stability by temperature depending on whether or not the catalyst is doped

5 is a diagram showing the reaction activity by temperature and long-term stability at 750°C without H ₂ S of a catalyst doped with 10 mol% Ru (SYTRu10) and a supported catalyst (Ru 10 loaded SYT) as a methane conversion rate. . At this time, the pretreatment was not separately performed, and the temperature was raised to 750℃ while flowing N ₂ , and the performance was evaluated by changing the composition of the gas after 750℃.

Even if it contained the same amount of Ru, the activity was better than that of the doped catalyst-supported catalyst. In particular, it was confirmed that the difference in activity was more pronounced at low temperature. The difference in activity did not change even after a long operation of 100 hours or longer. .

Performance evaluation by catalyst doping content and temperature

6 is methane from 600° C. to 900° C. of a Ru 10 loaded SYT catalyst in which pure SYT and Ru are doped with 2, 5, 10 mol% of Ti, respectively, and Ru 10 loaded SYT catalyst in the same amount as SYTRu2, 5, 10 and This is a picture showing the carbon dioxide conversion rate.

In the case of metal-free SYT, the conversion activity of methane and carbon dioxide is hardly shown, and in the case of a catalyst doped or supported with Ru, the difference in methane and carbon dioxide conversion rates by temperature depending on the amount of doping or according to the catalyst manufacturing method such as doping and supporting. Looks.

Evaluating the performance of catalyst by reduction reaction time

7 is a diagram showing the methane conversion rate of the catalyst pretreated for 4, 12, and 24 hours in a 900°C 20% hydrogen atmosphere of the SYTRu5 catalyst, respectively. At a high temperature of 650° C. or higher, the difference in activity was not large, but it was confirmed that the difference in the same reaction increased as the reaction temperature decreased.

Long-term stability evaluation by reduction reaction time of catalyst (addition of sulfur)

FIG. 8 is a diagram showing the methane conversion rates at 900°C and 750°C, respectively, while supplying 100 ppm of H2S following FIG. 7. In the case of the catalyst pretreated for 4 hours and 10 hours, immediately after supplying H ₂ S to the reactant, While the activity was lowered, the catalyst that was pretreated for 24 hours maintained its activity even after a long operation of 100 hours or more. At a reaction temperature of 750℃, the activity decreased compared to the case without H ₂ S, but it was also maintained for more than 100 hours. .

Reduction reaction by time Sulfur resistance evaluation

9 shows the methane conversion rate in the presence of 100 ppm of H ₂ S at a reaction temperature of 900° C. after reduction treatment at 900° C. for 12 hours and 24 hours at 900° C. of a SYTRh5 catalyst in which 5 mol% of rhodium (Rh) is substituted in the place of Ti will be. In the case of the catalyst subjected to reduction treatment for 24 hours, there was a decrease in activity compared to the case where there was no reduction in activity, but the conversion rate was maintained at 90% or more, and the catalyst pretreated for 12 hours also had a rapid decrease in activity after H ₂ S injection, but unlike SYTRu5 in FIG. % Conversion was maintained without further reduction.

Doped According to particle type Sulfur resistance evaluation

FIG. 10 is a diagram for evaluating the methane dry reforming performance of catalysts subjected to hydrogen pretreatment at 900° C. for 24 hours at 900° C. of SYTRu5, SYTRh5, and SYTNi5 catalysts each substituted with 5 mol% of Ru, Rh and Ni in the presence of 100 ppm H ₂ S. to be.

In the case of the catalyst doped with Ru and Rh, which are noble metals, the conversion rate of 90% or more was maintained even in the presence of a high concentration of H ₂ S of 100 ppm, whereas in the case of the catalyst doped with Ni, about 40% was maintained. It is thought to be due to its weak resistance to sulfur compared to noble metals, but it was confirmed that it remained active for a long time nonetheless.

pure SYT Catalyst performance evaluation

11 shows the results of methane dry reforming in the presence of 100 ppm of H ₂ S at 900° C. after heating in an N ₂ atmosphere of a pure SYT catalyst. In the case of SYT, which was not doped or supported by metal, no sudden decrease in activity was observed in the presence of sulfur, but overall activity of less than 15% was maintained.

Catalyst observation

12 shows a TEM image and a Fast Fourier Transform (FFT) pattern before and after reduction treatment at 900° C. for 24 hours of a SYTRh10 catalyst. After the reduction treatment, it was observed that the Rh particles protruded from the surface, and looking at the Fourier transform result, it was confirmed that the perovskite crystal phase was maintained as shown in FIG. 3 above.

FIG. 13 shows SEM and TEM images of SYT (pure), SYTRu10 (doped), and Ru 10-loaded SYT (supported) catalysts. In the case of Ru-doped SYTRu10, reduction-treated Ru particles as in the TEM of SYTRh10 of FIG. It can be seen that in the case of the Ru loaded catalyst (Ru 10 loaded SYT), it was observed that the particles were aggregated.

14 is a photograph showing a TEM image of a SYTRu5 catalyst and a catalyst evaluated for dry reforming in the presence of H ₂ S after pretreatment at 900° C. for 4 hours and 24 hours, respectively. In the case of the catalyst pretreated for 4 hours, only the crystals became large without protruding Ru, whereas the particles became larger due to thermal sintering in the case of the catalyst pretreated for 24 hours, but small Ru particles of less than 10 nm were observed. It was confirmed that the size was maintained below nm.

15 is a diagram of elemental image mapping using TEM before and after methane dry reforming reaction of SYTRu10 and Ru 10 loaded SYT catalysts. In the figure, in the case of the catalyst doped with Ru after the reaction, only protruding Ru particles were observed, but in the case of the supported catalyst, agglomeration was confirmed.

FIG. 16 shows changes in surface composition analyzed by SEM/EDX (SEM Energy Dispersive Spectrometer) method before and after methane dry reaction of SYT and SYTRu catalysts. When looking at the components of carbon after the reaction, there is no significant difference compared to that before the reaction. Through this, it can be seen that carbon that can be generated during the dry reforming reaction is not accumulated on the catalyst surface.

As described above, specific parts of the present invention have been described in detail, and it is obvious that these specific techniques are only preferred embodiments for those of ordinary skill in the art, and the scope of the present invention is not limited thereby. something to do. Accordingly, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (9)

As a method for producing an electrode catalyst for a fuel cell,
Doping and substituting a part of Ti with a noble metal or a transition metal in the perovskite material represented by Formula 1 below; And
Reducing the doped-substituted perovskite material at 850° C. or higher for 20 hours or more; Method for producing an electrode catalyst for a fuel cell comprising:
[Formula 1]
Sr _1-y Y _y TiO _3-z
In Formula 1, 0<y<1 and 0<z<1. The method of claim 1,
The step of substituting the doping is performed by the Pecchini method, a method of manufacturing an electrode catalyst for a fuel cell. The method of claim 1,
The reducing step is to be performed using an inert gas in a hydrogen atmosphere, a method for producing an electrode catalyst for a fuel cell. The method of claim 3,
The inert gas is at least one selected from the group consisting of nitrogen, helium, and argon, a method of manufacturing an electrode catalyst for a fuel cell. The method of claim 1,
The reducing step is to elute (exsolution) the noble metal or transition metal on the perovskite material, the method of manufacturing an electrode catalyst for a fuel cell. As a method of improving the sulfur resistance and carbon deposition resistance of an electrode catalyst for a fuel cell,
Doping and substituting a part of Ti with a noble metal or a transition metal in the perovskite material represented by Formula 1 below; And
Reducing the doped-substituted perovskite material at 850° C. or higher for 20 hours or more; a method for improving sulfur resistance and carbon deposition resistance of an electrode catalyst for a fuel cell comprising:
[Formula 1]
Sr _1-y Y _y TiO _3-z
In Formula 1, 0<y<1 and 0<z<1. As an electrode catalyst for fuel cells,
An electrode catalyst for a fuel cell represented by the following Formula 2, wherein M is eluted on a perovskite material, and the eluted M is in the form of degraded particles:
[Formula 2]
Sr _1-y Y _y Ti _1-x M _x O _3-z
In Formula 2, 0<x<1, 0<y<1, and 0<z<1,
M is a noble metal or a transition metal. The method of claim 7,
The fuel cell electrode catalyst is used for methane dry reforming. Methane dry reforming method using the electrode catalyst for a fuel cell according to claim 7.

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