Conductive catalyst for reforming biogas and by-product gas, method for preparing same, and method for producing hydrogen and synthetic gas using same

Abstract

The present invention relates to a conductive catalyst, a method for preparing same, and a method for producing hydrogen and synthetic gas using same. The conductive catalyst may comprise: a structure having a first-1 particle diameter with an average particle diameter of 700-1200 ㎛, the structure including a porous support and an active metal supported on the porous support; and a high-temperature conductive material having a second-1 particle diameter, or may comprise: a structure having a first-2 particle diameter and including a porous support and an active metal supported on the porous support; and a high-temperature conductive material having a second-2 particle diameter, the high-temperature conductive material being mixed with the structure, wherein the structure and the high-temperature conductive material may each independently have a pellet form, and the first-2 particle diameter and the second-2 particle diameter may be 200-700 ㎛.

Description

Conductive catalyst for biogas and by-product gas reforming, method for producing the same, and method for producing hydrogen and synthesis gas using the same

[0001] The present invention relates to a conductive catalyst for reforming biogas and by-product gas, a method for producing the same, and a method for producing hydrogen and synthesis gas using the same.

[0002] In addition to the intended products, the petrochemical industry also produces large quantities of byproduct gases, including carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2). Meanwhile, organic waste generated from industrial sites and daily life is typically disposed of through landfill or incineration. However, landfill or incineration poses a problem: the decomposition of the waste releases biogas containing methane and carbon dioxide.

[0003] Accordingly, research is underway to convert the massive amounts of byproduct gases and biogas emitted during petrochemical processes and waste treatment into hydrogen and synthesis gas. Synthesis gas is a mixed gas containing hydrogen and carbon monoxide. It serves as an intermediate feedstock for synthesizing various compounds, including ammonia and methanol. This gas possesses high industrial value and potential applications in renewable energy.

[0004] Synthesis gas production involves a reforming reaction of raw material gas, including by-product gas and biogas, which is performed in a reactor loaded with a catalyst. Conventional raw material gas reforming reactions typically utilize catalysts in which active metal particles are supported on a porous support. However, when dry reforming raw material gas using these catalyst particles, there is a problem in that carbon components, such as coke, are deposited on the surface and interior of the catalyst, deactivating the catalyst. Wet reforming reduces carbon deposition compared to dry reforming, but the process is complex and carries a risk of catalyst deterioration due to the high temperature at which the reaction is performed.

[0005] Meanwhile, research is being conducted to improve catalytic reactivity by using electric fields, plasma, etc. in addition to heat source supply, but there is a problem that carbon deposition can be prevented only when the molar ratio of oxidizer and reactant contained in the raw material gas is 1.4 or more, and a large amount of oxidizer is included compared to the reactants.

[0006] Accordingly, there is a need for research on a conductive catalyst for biogas and by-product gas reforming that has high reaction activity while preventing coke deposition on the catalyst.

[0007] The purpose of the present invention is to solve the problems of the above-mentioned prior art, and to provide a conductive catalyst for reforming biogas and by-product gas, which prevents deposition of carbon components and thus has improved stability and lifespan, and a method for producing hydrogen and synthesis gas using the same.

[0008] Another object of the present invention is to provide a conductive catalyst for reforming biogas and by-product gas, which has remarkably improved reaction efficiency and excellent biogas and by-product gas conversion rates, and a method for producing hydrogen and synthesis gas using the same.

[0009] Another object of the present invention is to provide a method for manufacturing a conductive catalyst for biogas and by-product gas reforming, which is easy to mass-produce and has a simplified process.

[0010] A conductive catalyst according to one aspect of the present invention is a catalyst comprising a porous support and a structure having a first-first particle size including an active metal supported on the porous support; and a high-temperature conductive material having a second-first particle size; wherein the catalyst has an average particle size of 700 to 1200 μm.

[0011] According to another aspect of the present invention, a conductive catalyst comprises a structure having first-second particle sizes, including a porous support and an active metal supported on the porous support; and a high-temperature conductive material having second-second particle sizes mixed with the structure; wherein the structure and the high-temperature conductive material each independently have a pellet shape, and the first-second particle size and the second-second particle size may be 200 to 700 μm.

[0012] In one example, the mass ratio of the structure: high-temperature conductive material may be 1:0.5 to 3.

[0013] In one example, the catalyst may be a catalyst for reforming biogas or by-product gas.

[0014] In one example, the high-temperature conductive material may include at least one selected from the group consisting of yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinium doped-ceria (GDC), samarium doped-ceria, and lanthanum gallates.

[0015] In one example, the active metal may include a group Ⅷ element or a group Ⅵ element.

[0016] In one example, the first-second particle diameter (D 1-2 ) and the above 2-2 diameter (D 2-2 ) of the ratio (D) 1-2 / D 2-2 ) can be 0.5 to 2.

[0017] In one example, the catalyst may be in the form of a pellet in which structural particles having a first-first particle size and high-temperature conductive material particles having a second-first particle size are mixed.

[0018] In one example, the pellet may be a structure particle having a first-first particle size and a high-temperature conductive material particle having a second-first particle size uniformly dispersed therein.

[0019] In one example, the catalyst may be a pellet-shaped structural particle and a high-temperature conductive material particle uniformly dispersed therein.

[0020] The present invention includes a method for producing the above-described conductive catalyst.

[0021] A method for producing a conductive catalyst according to the present invention comprises the steps of: producing a structure in which active metal particles are supported on a porous support; independently pelletizing the structure and a high-temperature conductive material to produce a structure having a first-second particle size and a high-temperature conductive material having a second-second particle size; and uniformly mixing the structure particles having the first-second particle size and the high-temperature conductive material particles having the second-second particle size; wherein the first-second particle size and the second-second particle size are 200 to 700 μm.

[0022] The present invention includes a method for producing hydrogen and synthesis gas using the above-described conductive catalyst.

[0023] The method for producing hydrogen and synthesis gas according to the present invention comprises the steps of (S1) applying an electric field to a reactor including the conductive catalyst described above; (S2) supplying a reaction gas including methane and carbon dioxide and an oxidizing agent to the reactor to which the electric field is applied; and (S3) reforming the reaction gas to obtain hydrogen and synthesis gas.

[0024] In one example, the step (S3) may be a process in which methane is reformed by a method selected from the group consisting of steam reforming, dry reforming, and dual reforming.

[0025] In one example, the molar ratio of the oxidizing agent:reactant gas may be 0.5 to 2:1.

[0026] In one example, the oxidizing agent may include carbon dioxide, water, or a combination thereof.

[0027] The conductive catalyst for reforming biogas and by-product gas of the present invention and the method for producing hydrogen and synthesis gas using the same can improve reaction stability and catalyst life by minimizing the deposition of carbon components on the surface and inside of the catalyst.

[0028] In addition, the conversion rate of biogas and by-product gas can be significantly improved with excellent reaction efficiency.

[0029] The method for manufacturing a conductive catalyst for reforming biogas and by-product gas of the present invention has the advantages of a simplified process and ease of mass production.

[0030] Figure 1 is a schematic diagram illustrating a conductive catalyst manufactured by a method according to Manufacturing Example 1.

[0031] Figure 2 is a schematic diagram illustrating a conductive catalyst manufactured by a method according to Manufacturing Example 2.

[0032] Figure 3 is a schematic diagram illustrating a conductive catalyst manufactured by a method according to Manufacturing Example 4.

[0033] Figure 4 is a schematic diagram illustrating a hydrogen and synthesis gas production device according to one embodiment.

[0034] Figure 5 is a graph showing the conversion rates of methane (CH4) and carbon dioxide (CO2) measured when producing hydrogen and synthesis gas using the methods of Example 1, Example 2, and Comparative Examples 1 to 5.

[0035] Figure 6 is a graph showing the conversion rates of methane (CH4) and carbon dioxide (CO2) measured when producing hydrogen and synthesis gas using the methods of Example 3, Example 4, and Comparative Examples 6 to 10.

[0036] FIG. 7 is a diagram showing the results of thermogravimetric analysis (TGA) of a catalyst when producing hydrogen and synthesis gas using the methods of Example 1, Comparative Example 1, and Comparative Example 5.

[0037] Figure 8 is a graph showing the methane and carbon dioxide conversion rates measured when producing hydrogen and synthesis gas using the methods according to Examples 7 and 8.

[0038] Figure 9 is a graph showing the conversion rates of methane (CH4) and carbon dioxide (CO2) measured when producing hydrogen and synthesis gas using the methods of Example 5 and Comparative Example 11.

[0039] Figure 10 is a graph showing the results of thermogravimetric analysis (TGA) of a catalyst when producing hydrogen and synthesis gas using the methods of Example 5, Comparative Example 11, and Comparative Example 14.

[0040] Figure 11 is a transmission electron microscope (TEM) image of the surface of a catalyst observed after producing synthesis gas using the methods of Example 5, Comparative Example 11, and Comparative Example 14.

[0041] The present invention provides a conductive catalyst for reforming biogas and by-product gas, a method for producing the same, and a method for producing hydrogen and synthesis gas using the same. The terminology used in this specification has been selected from widely used terms as much as possible, taking into account the functions of the present invention. However, this may vary depending on the intentions of engineers working in the relevant fields, precedents, the emergence of new technologies, etc. Unless otherwise defined, the technical and scientific terms used may have the meaning commonly understood by those of ordinary skill in the technical field to which this invention pertains.

[0042] In this specification and the appended claims, the terms “include” or “have” mean that a feature or component described in the specification is present, and unless specifically limited, does not preclude the possibility that one or more other features or components may be added.

[0043] In this specification and the appended claims, the terms first, second, etc. are not used in a limiting sense but are used for the purpose of distinguishing one component from another.

[0044] As used herein and in the appended claims, the singular expression "a" includes the plural expression unless the context clearly dictates otherwise. Furthermore, the plural expression "a" includes the singular expression unless the context clearly dictates otherwise.

[0045] Additionally, the numerical ranges used herein include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0046] The term "about" or the like used in this specification and the appended claims is used to encompass the tolerance when an tolerance exists.

[0047] The term “syngas” as used in this specification and the appended claims means an artificially manufactured gas, a mixed gas containing hydrogen and carbon monoxide.

[0048] In addition to the intended products, the petrochemical industry also generates large quantities of byproduct gases, including carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2). Furthermore, organic waste generated from industrial sites and daily life is disposed of through landfill or incineration. During landfill or incineration, the waste decomposes, releasing biogas containing methane and carbon dioxide.

[0049] Biogas and by-product gases contain significant greenhouse gases, so research is underway to convert these massive quantities into synthesis gas. Syngas is a mixed gas containing hydrogen and carbon monoxide, used as an intermediate feedstock for synthesizing various compounds, including ammonia and methanol. It has high industrial value and potential for use in renewable energy.

[0050] Synthesis gas production involves a reforming reaction of raw material gas, including by-product gas and biogas. Conventionally, this reforming reaction is performed in a reactor filled with a catalyst containing active metal particles supported on a porous support. However, when dry reforming of raw material gas using these catalyst particles, there is a problem in that carbon components such as coke are deposited on the surface and interior of the catalyst, causing catalyst deactivation. While wet reforming reduces carbon deposition somewhat compared to dry reforming, the process is complex and carries the risk of catalyst deterioration due to the high temperature at which the reaction is performed.

[0051] Meanwhile, research is being conducted to improve catalytic reactivity by using electric fields, plasma, etc. in addition to heat source supply, but carbon deposition can be prevented only when the molar ratio of oxidant to reactant contained in the reaction gas is 1.4 or more, and a large amount of oxidant is included relative to the reactant.

[0052] Accordingly, the present applicant has achieved the production of a conductive catalyst that improves the reaction gas conversion rate with excellent catalytic activity while preventing coke from being deposited on the catalyst surface and inside the catalyst even when a small amount of oxidizing agent is included during a reforming reaction.

[0053] A conductive catalyst according to a first aspect of the present invention is a catalyst comprising a porous support and a structure having a first-first particle size including an active metal supported on the porous support; and a high-temperature conductive material having a second-first particle size; wherein the catalyst has an average particle size of 700 to 1200 μm.

[0054] The catalyst including the structure and the high-temperature conductive material exhibits high catalytic activity within the above particle size range, thereby improving the synthesis gas yield, and when reforming a reaction gas including by-product gas and / or biogas, the reaction gas has an oxidant / methane ratio of 1.2 or less, so that even if the reaction gas contains a small amount of oxidant, carbon components are not deposited on the catalyst surface, thereby improving the reaction stability and catalyst life. More specifically, in the first aspect, the average particle size of the conductive catalyst may be 700 to 1200 μm or 750 to 1100 μm, and preferably 800 to 1000 μm.

[0055] In the first aspect, the conductive catalyst may be in the form of a pellet in which structural particles (11) having a first-first particle size and high-temperature conductive material particles (21) having a second-first particle size are mixed, as illustrated in FIG. 1. The conductive catalyst particles (30) having a pellet shape in which very small-sized structural particles (11) and high-temperature conductive material particles (21) are compressed and molded can minimize sintering of active metal particles during a catalytic reaction, and as the catalyst density is improved, the electrical conductivity is improved when a current is applied, thereby exhibiting high catalytic activity.

[0056] In one example, the first-first diameter (D 1-1) and the above 2-1 diameter (D 2-1 ) of the ratio (D) 1-1 / D 2-1 ) may be 0.01 to 100, 0.05 to 50, or 0.1 to 10. When the structure (11) having a size of several to several tens of micrometers and the high-temperature conductive material (21) have the above particle size ratio, the carbon component can be prevented from being deposited in the pores inevitably formed by the empty space between the structure (11) and the high-temperature conductive material (21), thereby preventing catalyst deactivation.

[0057] In one example, the method for producing a conductive catalyst according to the first aspect may include the steps of producing a structure having a first particle size of 1-1, in which active metal particles are supported on a porous support; producing a mixed powder by mixing the structure having the first particle size of 1-1 and a high-temperature conductive material having a second particle size of 2-1; and producing catalyst particles having a particle size of 700 to 1200 μm by pelletizing the mixed powder.

[0058] A conductive catalyst having a particle size of 700 to 1200 μm can be manufactured by a simple method of pelletizing a mixed powder of a structural powder and a high-temperature conductive material powder, thereby manufacturing a catalyst having excellent stability and reaction activity.

[0059] In addition, a conductive catalyst according to a second aspect of the present invention includes, as illustrated in FIG. 2, a structure (12) having a first-second particle size including a porous support and an active metal supported on the porous support; and a high-temperature conductive material (22) having a second-second particle size mixed with the structure; wherein the structure (12) and the high-temperature conductive material (22) each independently have a pellet shape, and the first-second particle size and the second-second particle size are 200 to 700 μm.

[0060] The structure and the high-temperature conductive material exist in the form of pellets with an average particle diameter of 200 to 700 ㎛, 250 to 650 ㎛, or 300 to 600 ㎛, respectively, so that high reaction activity can be achieved even at low temperatures and catalyst deactivation due to carbon deposition can be minimized. In addition, as described below, the catalyst manufacturing process is simple, so there is an advantage of easy mass production.

[0061] In the second aspect, the first-second particle size (D 1-2 ) and the above 2-2 diameter (D 2-2 ) of the ratio (D) 1-2 / D 2-2 ) may be 0.5 to 2, 0.7 to 1.7, or 0.9 to 1.5. At the above particle size ratio, the carbon component can be minimized from being deposited in the gap between the structure (12) and the high-temperature conductive material (22), thereby improving long-term stability. In addition, the catalyst has a pellet-shaped structure particle (12) and a high-temperature conductive material particle (22) that are uniformly dispersed within the reactor, so that the catalyst is quickly activated when an electric field is applied, thereby converting the reaction gas at a high conversion rate even at low temperatures.

[0062] In the first or second aspect, the catalyst may be a catalyst for reforming biogas or by-product gas. Biogas and by-product gas contain massive amounts of methane (CH4), carbon dioxide (CO2), etc., and may inevitably be generated during chemical product production processes or waste treatment processes. By reacting biogas and by-product gas, which contribute to environmental pollution, with the conductive catalyst of the present invention, they are converted into high value-added synthesis gas, thereby reducing greenhouse gas emissions.

[0063] In the first aspect or the second aspect, the mass ratio of the structure: high-temperature conductive material may be 1:0.5 to 3, 1:0.7 to 2.7, or 1:1 to 2. At the mass ratio, not only is the conductivity improved, thereby enhancing catalytic activity, but also the deposition of carbon components during the catalytic reaction can be prevented, thereby enhancing reaction stability.

[0064] In the first aspect or the second aspect, the high-temperature conductive material may adopt a material that can improve conductivity when current is applied to the catalyst, and more specifically, may include a ceramic material having high conductivity at high temperatures. For example, the high-temperature conductive material may include at least one selected from the group consisting of yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinium-doped-ceria (GDC), samarium-doped-ceria, and lanthanum gallates, and preferably, yttria-stabilized zirconia (YSZ).

[0065] In the first aspect or the second aspect, the structure may include a porous support and an active metal supported on the porous support, and the particle size ratio of the porous support: active metal particles may be 1:0.0001 to 0.01, 1:0.0005 to 0.01, or 0.001 to 0.01. By using active metal particles having a significantly smaller size compared to the structure, the catalytic activity is significantly improved, and catalyst deactivation due to deposition of carbon components can be minimized.

[0066] The above active metal may include a Group VIII element or a Group VI element. More specifically, the active metal may include nickel (Ni), iron (Fe), cobalt (Co), ruthenium (Ru), palladium (Pd), platinum (Pt), molybdenum (Mo), tungsten (W) or an alloy thereof, but preferably includes nickel (Ni) which has excellent economic efficiency and catalytic activity. In this case, “Group VIIIA element” and “Group VI element” refer to elements corresponding to their respective groups in the periodic table according to the old IUPAC (International Union of Pure and Applied Chemistry).

[0067] The porous support may include at least one selected from the group consisting of alumina (Al₂O₃), ceria (CeO2), titanium oxide (TiO2), porous silica (SiO2), zirconia (ZrO2), magnesium oxide (MgO), activated charcoal, graphene, carbon nanotubes (CNT), porous carbon, and graphite. Preferably, it may include gamma-phase alumina, but the present invention is not limited by the specific types of the active metal and the porous support.

[0068] The present invention includes a method for producing the conductive catalyst described above and a method for producing hydrogen and synthesis gas using the conductive catalyst. In detailing the method for producing the conductive catalyst of the present invention and the method for producing hydrogen and synthesis gas using the same, the materials, structures, shapes, sizes, etc., such as the structural body and high-temperature conductive material included in the conductive catalyst are the same as or similar to those described above, and therefore the method for producing the conductive catalyst and the method for producing hydrogen and synthesis gas according to the present invention include all of the contents described above with respect to the conductive catalyst.

[0069] A method for producing a conductive catalyst according to the present invention comprises the steps of: producing a structure in which active metal particles are supported on a porous support; independently pelletizing the structure and a high-temperature conductive material to produce a structure having a first-second particle size and a high-temperature conductive material having a second-second particle size; and uniformly mixing the structure particles having the first-second particle size and the high-temperature conductive material particles having the second-second particle size; wherein the first-second particle size and the second-second particle size are 200 to 700 μm.

[0070] Since the conductive catalyst is manufactured by a simple method of pelletizing and then mixing the structural powder and the high-temperature conductive material powder, it has the advantage of being easy to mass-produce.

[0071] In one example, the structure manufacturing step may include a step of mixing an active metal precursor and a porous support; and a step of heat-treating the mixture. More specifically, the active metal precursor and the porous support powder may be mixed by ball milling, and the mixture may be aged at 50 to 70°C to support the active metal on the porous support. Thereafter, the porous support powder on which the active metal is supported may be heat-treated to uniformly disperse the active metal within the porous support. The heat treatment may be performed at a temperature range of 500 to 700°C under hydrogen gas.

[0072] The manufactured structure may contain 5 to 40 parts by weight, 6 to 35 parts by weight, or 7 to 30 parts by weight of active metal particles based on 100 parts by weight of the structure. A high content of active metal particles can be highly dispersed within the porous support to improve catalytic activity.

[0073] The active metal precursor may include at least one selected from the group consisting of sulfates, nitrates, carbonates, oxides, hydroxides, chlorides, and hydrates thereof of Group VIIIA elements or Group VI elements. For example, when the active metal precursor includes nickel, the active metal precursor may include at least one selected from the group consisting of nickel hydroxide, nickel sulfate, nickel carbonate, nickel nitrate, nickel chloride, and hydrates thereof, but the present invention is not limited by the specific type of the metal precursor.

[0074] For example, the structure and the high-temperature conductive material may be mixed at a mass ratio of 1:0.5 to 3, 1:0.7 to 2.7, or 1:1 to 2. At the mass ratio, not only is the conductivity improved, thereby enhancing the catalytic activity, but also the deposition of carbon components during the catalytic reaction can be prevented, thereby enhancing the reaction stability.

[0075] The conductive catalyst manufactured by this method exhibits excellent catalytic activity when an electric field is applied, which not only significantly improves the reaction gas conversion rate, but also has the effect of improving long-term stability by minimizing carbon component deposition and reducing the irreversible deactivation rate of the catalyst.

[0076] The present invention includes a method for producing hydrogen and synthesis gas using the above-described conductive catalyst.

[0077] The method for producing hydrogen and synthesis gas according to the present invention comprises the steps of (S1) applying an electric field to a reactor including a conductive catalyst according to the first or second aspect described above; (S2) supplying a reaction gas including methane and an oxidant to the reactor to which the electric field is applied; and (S3) reforming the reaction gas to obtain a synthesis gas.

[0078] The above reaction gas may contain a large amount of by-product gas, biogas, or a mixture thereof containing large amounts of methane (CH4) and carbon dioxide (CO2). As described above, waste gases emitted from the petrochemical industry and waste treatment processes can be converted into high-value-added synthesis gas containing hydrogen and carbon monoxide as reactants, significantly reducing greenhouse gas emissions and achieving carbon neutrality, which is advantageous from an environmental perspective.

[0079] The oxidizing agent may include carbon dioxide, water, or a combination thereof, and an appropriate oxidizing agent may be selected according to the reforming method described below. When using the conductive catalyst of the present invention, synthesis gas can be obtained with a high conversion rate even in a harsh environment with a small amount of oxidizing agent added, and at the same time, catalyst deactivation due to carbon component deposition can be minimized, thereby extending the catalyst replacement cycle. For example, the molar ratio of oxidizing agent to methane may be 0.5 to 2:1 or 0.7 to 1.5:1, and preferably 1 to 1.2:1.

[0080] The above reactor is a reactor capable of applying current, and specifically, may be a low-temperature plasma reactor, and more specifically, may be a dielectric barrier discharge (DBD) plasma reactor. By applying an electric field to the reactor to generate plasma, a reaction gas containing methane and carbon dioxide can be converted into synthesis gas at a high conversion rate even at a low temperature. Accordingly, a decarbonization process is possible, and greenhouse gases can be drastically reduced. Specifically, the reaction temperature of the step (S3) is 400 to 800°C, 450 to 750°C, or 500 to 700°C, so that the reforming reaction can be performed at a high conversion rate even at a low temperature.

[0081] The above step (S3) may reform the reactants by one method selected from the group including steam reforming, dry reforming, and dual reforming, and it may be advantageous to perform the dual reforming reaction in terms of improving the conversion rate and preventing catalyst coking. The conductive catalyst of the present invention can have excellent methane and carbon dioxide conversion rates regardless of the reforming method of the reaction gas.

[0082] For example, when step (S3) is performed via steam reforming, additional steam can be added during the reaction gas addition to produce synthesis gas. Steam reforming has the advantage of minimizing catalyst deactivation due to carbon deposition, while dry reforming has the advantage of maximizing the synthesis gas yield.

[0083] For example, steam reforming may involve reaction scheme 1, dry reforming may involve reaction scheme 2, and double reforming may involve reaction scheme 3.

[0084] [Reaction Formula 1]

[0085] CH4+ H2O → CO + 3H2

[0086] [Reaction Formula 2]

[0087] CH4+ CO2→ 2CO + 2H2

[0088] [Reaction Formula 3]

[0089] 2CH4+ CO2+ H2O → 3CO + 5H2

[0090] Hereinafter, the present invention will be described in more detail through examples.

[0091] (Manufacturing Example 1)

[0092] Gamma-phase alumina (γ-Al2O3) powder (Alfa Aesar, surface area = 255 m 2 / g, pore volume=1.12 cm 3 / g) 2 g and 1.1010 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O, mp = 56 ℃) were mixed in a ball mill. The mixture was placed in a polypropylene bottle with a wide mouth and aged at 60 ℃ for 2 hours at a rotation speed of 5 rpm in a rotating oven. Afterwards, the temperature was increased to 600 ℃ for 2 hours while flowing hydrogen gas at 100 cc / min in a tube furnace, and calcined for 4 hours to obtain a structure in which 10 wt% of nickel was supported on an alumina support.

[0093] The manufactured structure was dried in a vacuum oven at 60 °C, and the dried structure powder and yttrium stabilized zirconia (Sigma-Aldrich) powder were mixed at a mass ratio of 1:2 and ground finely in a mortar and pestle for more than 10 minutes to manufacture a mixed powder. The mixed powder was pelletized (6 ton, 10 min) to manufacture a conductive catalyst having a particle size of 800 to 1000 μm as shown in Fig. 1.

[0094] (Manufacturing Example 2)

[0095] As shown in Fig. 2, a conductive catalyst was manufactured in the same manner as in Manufacturing Example 1, except that the structure and yttria-stabilized zirconia were each independently pelletized to manufacture structure particles and high-temperature conductive material particles having a particle size of 300 to 600 μm, and then these were mixed.

[0096] (Manufacturing Example 3)

[0097] A conductive catalyst was manufactured in the same manner as in Manufacturing Example 1, except that a structure in which 30 wt% of nickel was supported on an alumina support was manufactured.

[0098] (Manufacturing Example 4)

[0099] A conductive catalyst was manufactured using the same method as in Manufacturing Example 1, but the pellets were sieved to manufacture a conductive catalyst having a particle size of 300 to 600 μm as shown in Fig. 3.

[0100] (Manufacturing Example 5)

[0101] Manufactured in the same manner as Manufacturing Example 1, but using only the structure and not mixing in yttria-stabilized zirconia.

[0102] (Manufacturing Example 6)

[0103] A commercial catalyst (Sud-Chemie, FCR-70) containing nickel (Ni) supported on calcium aluminate was used.

[0104] (Example 1)

[0105] 1 g of the catalyst of Preparation Example 1 was fixed inside a dielectric barrier discharge (DBD) reactor. A current of 9 mA was applied to the reactor, the reactor temperature was set to 700°C, and the catalyst was reduced for 1 hour while flowing hydrogen gas. Afterwards, reaction gas and steam were added to perform a dual reforming reaction of biogas for 10 hours. The space velocity was 12,000 h -1 The oxidant / methane ratio containing water and carbon dioxide was 1.04, and the reaction gas simulated biogas with a volume ratio of methane and carbon dioxide of 65:35. The reaction was carried out at a pressure of 1 bar.

[0106] (Example 2)

[0107] The modification reaction was carried out in the same manner as in Example 1, except that the catalyst of Manufacturing Example 2 was used.

[0108] (Example 3)

[0109] The reforming reaction was carried out in the same manner as in Example 1, except that the reactor temperature was set to 650°C.

[0110] (Example 4)

[0111] The reforming reaction was carried out in the same manner as in Example 2, except that the reactor temperature was set to 650°C.

[0112] (Example 5)

[0113] 1 g of the catalyst of Preparation Example 1 was fixed inside a dielectric barrier discharge (DBD) reactor. A current of 9 mA was applied to the reactor, and the reactor temperature was set to 700°C. The catalyst was reduced for 1 hour while flowing hydrogen gas. Afterwards, methane and steam were added, and the steam reforming reaction was performed for 10 hours. The space velocity was 12,000 h -1 , the steam / methane ratio was 3, and the reactor pressure was 1 bar.

[0114] (Example 6)

[0115] The modification reaction was carried out in the same manner as in Example 5, except that the catalyst of Manufacturing Example 2 was used.

[0116] (Example 7)

[0117] The catalyst of Manufacturing Example 3 was used, and the space velocity was 7200 h -1 Except that, the modification reaction was carried out in the same manner as in Example 5.

[0118] (Example 8)

[0119] Space speed is 7200 h -1 Except that, the modification reaction was carried out in the same manner as in Example 5.

[0120] (Comparative Example 1)

[0121] The reforming reaction was carried out in the same manner as in Example 1, except that no current was applied to the reactor and the reactor was heated to 700°C using a heater.

[0122] (Comparative Example 2)

[0123] The modification reaction was carried out in the same manner as in Comparative Example 1, except that the catalyst of Manufacturing Example 2 was used.

[0124] (Comparative Example 3)

[0125] The modification reaction was carried out in the same manner as in Example 1, except that the catalyst of Manufacturing Example 4 was used.

[0126] (Comparative Example 4)

[0127] The modification reaction was carried out in the same manner as in Comparative Example 1, except that the catalyst of Manufacturing Example 4 was used.

[0128] (Comparative Example 5)

[0129] The modification reaction was carried out in the same manner as in Comparative Example 1, except that the catalyst of Manufacturing Example 5 was used.

[0130] (Comparative Example 6)

[0131] The catalyst of Manufacturing Example 1 was used, and the reforming reaction was carried out in the same manner as Example 1, except that no current was applied to the reactor and the reactor was heated to 650°C using a heater.

[0132] (Comparative Example 7)

[0133] The modification reaction was carried out in the same manner as in Comparative Example 6, except that the catalyst of Manufacturing Example 2 was used.

[0134] (Comparative Example 8)

[0135] The modification reaction was carried out in the same manner as in Example 3, except that the catalyst of Manufacturing Example 4 was used.

[0136] (Comparative Example 9)

[0137] The modification reaction was carried out in the same manner as in Comparative Example 6, except that the catalyst of Manufacturing Example 4 was used.

[0138] (Comparative Example 10)

[0139] The modification reaction was carried out in the same manner as in Comparative Example 6, except that the catalyst of Manufacturing Example 6 was used.

[0140] (Comparative Example 11)

[0141] The reforming reaction was carried out in the same manner as in Example 5, except that no current was applied to the reactor and the reactor was heated to 700°C using a heater.

[0142] (Comparative Example 12)

[0143] The modification reaction was carried out in the same manner as in Comparative Example 11, except that the catalyst of Manufacturing Example 2 was used.

[0144] (Comparative Example 13)

[0145] The modification reaction was carried out in the same manner as in Example 5, except that the catalyst of Manufacturing Example 4 was used.

[0146] (Comparative Example 14)

[0147] The modification reaction was carried out in the same manner as in Comparative Example 11, except that the catalyst of Manufacturing Example 6 was used.

[0148] The types of catalysts, types of heat sources, reactor temperatures, and reforming methods used in the production of hydrogen and synthesis gas using the methods of Examples 1 to 8 and Comparative Examples 1 to 14 are summarized in Table 1 below.

[0149] Catalyst type, heat source type, space velocity, reactor temperature, reforming method, Example 1, Manufacturing example 1, electric field + heater, 12000 h -1 700℃ double reforming example 2 Manufacturing example 2 Electric field + heater 12000 h -1 700℃ double reforming example 3 Manufacturing example 1 Electric field + heater 12000 h -1 650℃ double reforming example 4 manufacturing example 2 electric field + heater 12000 h -1 650℃ double reforming example 5 manufacturing example 1 electric field + heater 12000 h -1 700℃ Steam Reformation Example 6 Manufacturing Example 2 Electric Field + Heater 12000 h -1700℃ Steam Reformation Example 7 Manufacturing Example 3 Electric Field + Heater 7200 h -1 700℃ Steam Reformation Example 8 Manufacturing Example 1 Electric Field + Heater 7200 h -1 700℃ Steam Reformation Comparison Example 1 Manufacturing Example 1 Heater 12000 h -1 700℃ double reforming comparison example 2 manufacturing example 2 heater 12000 h -1 700℃ double reforming comparative example 3 manufacturing example 4 electric field + heater 12000 h -1 700℃ double reforming comparison example 4 manufacturing example 4 heater 12000 h -1 700℃ double reforming comparison example 5 manufacturing example 5 heater 12000 h -1 700℃ double reforming comparison example 6 manufacturing example 1 heater 12000 h -1 650℃ double reforming comparative example 7 manufacturing example 2 heater 12000 h -1 650℃ double reforming comparative example 8 manufacturing example 4 electric field + heater 12000 h -1 650℃ double reforming comparative example 9 manufacturing example 4 heater 12000 h -1 650℃ double reforming comparative example 10 manufacturing example 6 heater 12000 h -1 650℃ double reforming comparative example 11 manufacturing example 1 heater 12000 h -1 700℃ Steam Reformation Comparative Example 12 Manufacturing Example 2 Heater 12000 h -1 700℃ Steam Reformation Comparative Example 13 Manufacturing Example 4 Electric Field + Heater 12000 h -1 700℃ Steam Reformation Comparative Example 14 Manufacturing Example 6 Heater 12000 h -1 700℃ steam reforming

[0150] (Experimental Example 1) Evaluation of dual reforming reaction performance

[0151] After the double reforming reaction according to the methods of Examples 1 to 4 and Comparative Examples 1 to 10, the gas concentration of the product was measured using gas chromatography, and the flow rate was measured using a gas meter to calculate each gas flow rate. Based on this, the methane conversion rate and carbon dioxide conversion rate were measured, and are shown in Figures 5 and 6 below.

[0152] FIG. 5 is a graph showing the methane conversion rate and carbon dioxide conversion rate measured when a dual reforming reaction was performed at a reaction temperature of 700°C. Referring to FIG. 5, in the case of Example 1 using the catalyst of Manufacturing Example 1 and Example 2 using the catalyst of Manufacturing Example 2, the methane conversion rate and carbon dioxide conversion rate were measured to be high values ​​exceeding the average conversion rate as the dual reforming reaction was performed by generating plasma by applying an electric field to the reactor. In the case of Comparative Examples 1 and 2, despite using the catalysts of Manufacturing Examples 1 and 2, respectively, the reforming reaction was performed by heating the reactor using a heater without applying current, so the reaction activity was significantly lower than the equilibrium conversion rate.

[0153] Comparative Examples 3 and 4 using the conductive catalyst of Preparation Example 4 having an average particle size of 300 to 600 ㎛ In addition, Comparative Example 3, in which a current was applied to the reactor, showed higher methane conversion and carbon dioxide conversion than Comparative Example 4, in which a current was not applied. On the other hand, when producing hydrogen and synthesis gas using the method of Comparative Example 3, the carbon dioxide conversion was high, but the methane conversion was low even though a current was applied to the reactor, and it was confirmed that the reaction activity was lowered compared to the catalysts of Preparation Examples 1 and 2. In the case of Comparative Example 5 using the catalyst of Preparation Example 5, in which the catalyst does not include a high-temperature conductive material, both the methane conversion and carbon dioxide conversion showed values ​​lower than the equilibrium conversion, showing lower catalytic activity compared to Examples 1 and 2.

[0154] FIG. 6 is a graph showing the methane conversion rate and carbon dioxide conversion rate measured when a dual reforming reaction was performed at a reaction temperature of 650 ℃. As shown in FIG. 6, Examples 3 and 4, which produce synthesis gas using the catalysts of Preparation Examples 1 and 2, respectively, exhibited high methane conversion rates and carbon dioxide conversion rates higher than the equilibrium conversion rate because the dual reforming reaction was performed by applying an electric field to generate plasma when producing hydrogen and synthesis gas. On the other hand, in Comparative Examples 6 and 7, which used the catalysts of Preparation Examples 1 and 2, respectively, the carbon dioxide conversion rate and methane conversion rate were significantly lower than when producing synthesis gas by applying an electric field because the reactor was heated using a heater without applying an electric field when producing hydrogen and synthesis gas, indicating that the catalytic activity was low.

[0155] Comparing Comparative Examples 8 and 9 using the catalyst of Manufacturing Example 4, Comparative Example 8 with an electric field applied showed higher methane conversion and carbon dioxide conversion than Comparative Example 9 without an electric field applied, but Comparative Example 8 showed lower methane conversion and carbon dioxide conversion compared to Examples 3 and 4. Comparative Example 10 including the commercial catalyst of Manufacturing Example 6 also showed lower catalytic activity compared to Examples 3 and 4.

[0156] Accordingly, when a current was applied to a reactor filled with the catalyst of Manufacturing Example 1 or Manufacturing Example 2 to generate plasma and produce synthesis gas, high reforming reaction activity was exhibited even at a low temperature of 650°C.

[0157] FIG. 7 is a graph showing thermogravimetric analysis (TGA) of the catalyst during the double reforming reaction using the methods of Example 1, Comparative Example 1, and Comparative Example 5. As shown in FIG. 7, in the case of Example 1, since the conductive catalyst of Preparation Example 1 was included and the reaction was performed under conditions of applying an electric field, the mass change of the catalyst after the reforming reaction was very small at 0.35 wt%, resulting in a very low amount of carbon deposition. However, in the case of Comparative Example 1, although the conductive catalyst of Preparation Example 1 was included, an electric field was not applied, so the catalyst mass increased by 1.02 wt% during the reforming reaction, indicating that some carbon components were deposited on the catalyst. In the case of Comparative Example 5, which includes the catalyst of Preparation Example 5 that does not include a high-temperature conductive material, the catalyst mass increased by 1.49 wt%, confirming that the carbon component was deposited the most compared to Example 1 and Comparative Example 1.

[0158] In particular, when double reforming of a reaction gas through an electric field-imposed catalytic reaction using the conductive catalyst of the present invention, excellent carbon deposition stability was shown with a carbon deposition amount of 0.35 wt% even under poor reaction conditions using a small amount of oxidant with an oxidant (CO2+H2O) / methane ratio of 1.04.

[0159] (Experimental Example 2) Steam reforming reaction performance evaluation

[0160] After the steam reforming reaction according to the methods of Example 5, Example 7, Example 8, and Comparative Example 5, the gas concentration of the product was measured using gas chromatography, and the flow rate was measured using a gas meter to calculate each gas flow rate. Based on this, the methane conversion rate was measured, and is shown in Figures 8 and 9 below.

[0161] Figure 8 is a graph measuring the methane conversion rate according to the reaction temperature during the steam reforming reaction by the methods of Examples 7 and 8, respectively. When hydrogen and synthesis gas were produced by the methods of Example 7 using the catalyst of Production Example 3 and Example 8 using the catalyst of Production Example 1, the methane conversion rate was significantly higher than the equilibrium conversion rate. In particular, even at a low temperature of 400°C, Examples 7 and 8 showed methane conversion rates of 63.2% and 85.0%, respectively, which were significantly higher than the equilibrium conversion rate (19.8%), and when the reaction temperature increased to 500°C or higher, a methane conversion rate of 95% or higher was shown.

[0162] Fig. 9 is a graph showing the methane conversion rate according to the reaction temperature during the steam reforming reaction according to the methods of Example 5 and Comparative Example 11. Referring to Fig. 9, when hydrogen and synthesis gas were produced using the catalyst of Production Example 1 at 400°C by the method of Example 5, a high methane conversion rate of about 55% was observed. However, in Comparative Example 11, where synthesis gas was produced by heating the reactor using a general heater without applying an electric field to the reactor, the methane conversion rate was only 48% even when the temperature increased to 530°C, confirming that it had a significantly lower catalytic activity compared to Example 5 where an electric field was applied.

[0163] FIG. 10 is a graph showing thermogravimetric analysis (TGA) of a catalyst during a steam reforming reaction using the methods of Example 5, Comparative Example 11, and Comparative Example 14, and FIG. 11 is a transmission electron microscope (TEM) image showing the shape of a catalyst after a steam reforming reaction at 700°C using the methods of Example 5, Comparative Example 11, and Comparative Example 14.

[0164] As shown in FIGS. 10 and 11, in Example 5, where an electric field was applied to the catalyst of Manufacturing Example 1 to produce synthesis gas, it was confirmed that there was almost no change in mass before and after the steam reforming reaction even at high temperatures, and that carbon components were not deposited inside the catalyst, thus having excellent stability. In Comparative Example 14, which used the commercial catalyst of Manufacturing Example 6, the mass increased by about 10% at 500°C or higher, and it can be seen in the TEM image that a large amount of coke was deposited on the catalyst. In Comparative Example 11, where an electric field was not applied to the catalyst of Manufacturing Example 1 and it was heated using a heater, the catalyst mass increased by about 1% at 600°C or higher, and it can be seen in the TEM image that a small amount of coke was deposited on the catalyst. Accordingly, by applying current to the reactor while using the catalyst of Manufacturing Example 1, the methane conversion rate was improved due to high reaction activity by reforming the reaction gas through low-temperature plasma reaction, and carbon deposition was minimized to prevent deactivation of the catalyst.

[0165] In summary, when a methane reforming reaction is performed by applying a current to a reactor filled with the conductive catalyst of Preparation Example 1, which includes a structure and a high-temperature conductive material and has an average particle diameter of 700 to 1200 ㎛, or a conductive catalyst in which the structure and the high-temperature conductive material are mixed, each independently in the form of a pellet and the average particle diameter of the pellets is 200 to 700 ㎛, not only can a high methane conversion rate and carbon dioxide conversion rate be achieved with excellent catalytic activity even at low temperatures, but also the deposition of carbon components on the catalyst surface can be minimized even under harsh conditions with an oxidant (CO2+H2O) / methane ratio of 1.04, thereby providing long-term stability and improved catalyst lifespan. By producing high value-added synthesis gas containing hydrogen and carbon monoxide by consuming a large amount of methane and carbon dioxide, not only can greenhouse gas emissions be significantly reduced, but also the energy consumed for the conversion of methane and carbon dioxide can be reduced, thereby achieving carbon neutrality.

[0166] As described above, the present invention has been described with specific details and limited examples and drawings, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0167] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the following claims as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

[0168] [Explanation of symbols]

[0169] 10: Structure

[0170] 11: Structure having the 1-1 particle diameter

[0171] 12: Structure with 1-2 particle diameters

[0172] 20: High-temperature conductive material

[0173] 21: High-temperature conductive material having a 2-1 particle size

[0174] 22: High-temperature conductive material having a 2-2 particle size

[0175] 30: Conductive catalyst

Claims

1. A structure having a first-first particle size, including a porous support and an active metal supported on the porous support; and A catalyst comprising a high-temperature conductive material having a second-first particle size; The above catalyst is a conductive catalyst having an average particle size of 700 to 1200 ㎛.

2. A structure having first-second particle sizes, including a porous support and an active metal supported on the porous support; and A high temperature conductive material having a second-2 particle size mixed with the above structure; A conductive catalyst wherein the above structure and the high-temperature conductive material each independently have a pellet shape, and the first-second particle size and the second-second particle size are 200 to 700 ㎛.

3. In paragraph 1 or 2, The above structure: a conductive catalyst having a mass ratio of high temperature conductive material of 1:0.5 to 3.

4. In paragraph 1 or 2, The above catalyst is a conductive catalyst that is a catalyst for reforming biogas or by-product gas.

5. In paragraph 1 or 2, A conductive catalyst comprising at least one selected from the group consisting of yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinium doped-ceria (GDC), samarium doped-ceria, and lanthanum gallates.

6. In paragraph 1 or 2, The above active metal is a conductive catalyst containing a group VIII element or a group VI element.

7. In paragraph 2, The above 1-2 diameters (D 1-2 ) and the above 2-2 diameter (D 2-2 ) of the ratio (D) 1-2 / D 2-2 ) is a conductive catalyst of 0.5 to 2.

8. In paragraph 1, The above catalyst is a conductive catalyst in the form of a pellet in which structural particles having a first-first particle size and high-temperature conductive material particles having a second-first particle size are mixed.

9. In paragraph 8, The above pellet is a conductive catalyst in which structural particles having a first-first particle size and high-temperature conductive material particles having a second-first particle size are uniformly dispersed.

10. In paragraph 2, The above catalyst is a conductive catalyst in which structural particles having a pellet shape and high-temperature conductive material particles are uniformly dispersed.

11. A step of manufacturing a structure in which active metal particles are supported on a porous support; A step of independently pelletizing the above structure and the high-temperature conductive material to manufacture a structure having a first-second particle size and a high-temperature conductive material having a second-second particle size; and A step of uniformly mixing structural particles having the first-second particle size and high-temperature conductive material particles having the second-second particle size; A method for manufacturing a conductive catalyst, wherein the first and second particle sizes and the second and third particle sizes are 200 to 700 ㎛. 12.(S1) A step of applying an electric field to a reactor including a conductive catalyst according to any one of claims 1 and 2; (S2) a step of supplying a reaction gas containing methane and carbon dioxide and an oxidizer to the reactor to which the electric field is applied; and (S3) A method for producing hydrogen and synthesis gas, comprising: a step of reforming the reaction gas to obtain hydrogen and synthesis gas.

13. In paragraph 12, A method for producing hydrogen and synthesis gas, wherein the step (S3) comprises reforming methane by one method selected from the group consisting of steam reforming, dry reforming, and dual reforming.

14. In paragraph 12, A method for producing hydrogen and synthesis gas wherein the molar ratio of the above oxidizing agent:reactant gas is 0.5 to 2:

1.

15. In paragraph 12, A method for producing hydrogen and synthesis gas, wherein the oxidizing agent comprises carbon dioxide, water or a combination thereof.

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