Catalyst for producing synthesis gas by reforming reaction of reducing gas using carbon dioxide

Abstract

The present invention relates to a catalyst for producing a synthesis gas by reforming a reducing gas using carbon dioxide, and more particularly, to a catalyst for producing a synthesis gas in which a composite catalyst comprising nickel and cobalt, which is novel configured for reforming a reducing gas using carbon dioxide, is provided, and when the catalyst is used in a reforming reaction, the catalyst can be used as a catalyst for producing a synthesis gas by reforming a reducing gas using carbon dioxide. The catalyst shows excellent catalytic activity and stability, and realizes an excellent conversion rate of carbon-based reducing gas.

Description

Technical Field

[0001] This invention relates to a catalyst for producing syngas using carbon dioxide through reforming of reducing gas. More specifically, this invention relates to a catalyst for producing syngas that, when used in a reforming reaction utilizing carbon dioxide, exhibits excellent catalytic activity and stability, and provides excellent conversion of reducing gas. Background Technology

[0002] Unless otherwise specified herein, the contents described in this section are not considered prior art to the claims of this application, and their inclusion in this section does not imply that they constitute prior art.

[0003] In recent years, energy-related issues have become important social problems, and excessive emissions of greenhouse gases related to carbon dioxide have become serious environmental problems.

[0004] Recognizing the urgent need to develop and utilize renewable energy sources that can grow sustainably to ensure domestic and international energy security, renewable energy is being expanded, and various technologies are being developed to address environmental issues such as carbon dioxide capture and utilization.

[0005] South Korea is considered a major global emitter of greenhouse gases, and international pressure to reduce greenhouse gas emissions is increasing.

[0006] Hydrogen energy is gradually emerging as a key future clean energy source capable of simultaneously addressing environmental issues (such as global warming) and energy dependence. Developing technologies to utilize carbon dioxide as a cyclical carbon resource is a critical research priority.

[0007] Generally, methods for producing syngas (composed of hydrogen and carbon monoxide) include those using fossil fuels such as natural gas. Among these syngas production methods, from an economic perspective, utilizing biomass (such as carbon dioxide and methane gas) and using renewable energy sources is advantageous.

[0008] Existing methods for producing syngas from biogas include dry reforming, wet reforming, and combined reforming, which are summarized in the following reaction equations.

[0009] Dry reforming: CO2 + CH4 → 2CO + 2H2 (ΔH = 247 kJ / mol) Wet reforming: H₂O + CH₄ → 3H₂ + CO (ΔH = 226 kJ / mol) Combined reforming: CO2 + 3CH4 + 2H2O → 4CO + 8H2 (ΔH = 712 kJ / mol) In reforming reactions that utilize reducing gas, dry reforming is the syngas production technology that uses the largest amount of CO2 (a greenhouse gas) as a feedstock among catalytic reforming technologies. Its significant potential to reduce greenhouse gases has attracted global interest in acquiring this technology.

[0010] In particular, dry reforming requires a higher proportion of CO compared to other reforming reactions used in chemical production and has a significant impact on reducing greenhouse gases. Therefore, efforts are underway to develop superior reaction technologies.

[0011] However, dry reforming uses catalysts for the reaction, and the methane dry reforming (DRM) technology, which can reduce greenhouse gases, suffers from serious drawbacks due to its short catalyst lifetime, making commercialization difficult. In particular, methane dry reforming (DRM) utilizes carbon dioxide as a reactant in the largest possible amount, thereby reducing greenhouse gases, but it is associated with significant technical hurdles, including harsh high-temperature reaction conditions and short catalyst lifetime due to carbon buildup.

[0012] Existing dry reforming catalysts that can use CO2 as a feedstock have been under development for over 100 years. However, their lifespan remains very limited due to various factors, including catalyst deactivation and damage to the catalyst caused by carbon buildup.

[0013] Therefore, various studies have been proposed to extend catalyst lifetime in dry reforming. However, there is a lack of technical means other than attempting to extend lifetime by specifying the catalyst composition.

[0014] Regarding existing reforming catalysts, Korean Patent Registration No. 10-2194440 proposes a dry reforming catalyst comprising a metal oxide support containing hydroxyl groups on the catalyst surface and one or more active materials selected from nickel (Ni), cobalt (Co), ruthenium (Ru), palladium (Pd), iridium (Ir), platinum (Pt), and rhodium (Rh). This catalyst is proposed to exhibit excellent catalytic activity and long-term stability.

[0015] However, although some existing reforming reducing gas catalysts using carbon dioxide aim for long-term use, their reported catalyst lifetimes are limited to 1000 hours or less. Therefore, no technology has yet been proposed to ensure sufficient catalyst lifetime.

[0016] Therefore, there is an urgent need to develop technologies that improve the composition of catalysts used to produce syngas from carbon dioxide via reforming reduced gas, thereby increasing the efficiency of syngas production.

[0017] The present invention aims to solve the above-mentioned problems of the prior art by improving the reforming performance of various reducing gases when using carbon dioxide for reforming reactions, and in particular, to provide a catalyst for the production of syngas that can be used for a long time without producing carbon deposits.

[0018] In this invention, the invention was completed after extensive research into the characteristics and properties of the catalytically active components to solve the above-mentioned problems. Summary of the Invention

[0019] The problem the invention aims to solve Therefore, one object of the present invention is to provide a Ni-Co catalyst for reforming reducing gas in which almost no carbon deposition occurs, thus significantly extending the catalyst lifetime compared to previously proposed catalyst technologies.

[0020] Another object of the present invention is to provide a catalyst for the efficient production of syngas using carbon dioxide through reforming reducing gas by a novel configuration of the composition of a Ni-Co catalyst.

[0021] Another object of the present invention is to provide a catalyst for producing syngas that exhibits a significantly extended catalyst lifetime and excellent conversion rate by suppressing carbon buildup during the reforming of reducing gas using carbon dioxide.

[0022] The purpose of this invention is not limited to the above-described purposes, but should be understood to cover all purposes inferred from the detailed description or claims of this invention, as well as all purposes achievable based on the description or technical concept of this invention.

[0023] Problem Solving Methods To achieve the above-mentioned objectives of the present invention, the present invention can provide a catalyst for reforming reducing gas using carbon dioxide, comprising a catalyst support on which a mixed catalytic component containing nickel and cobalt is supported, wherein the nickel content is greater than the cobalt content, and the lifetime of the catalyst is 1500 hours or more based on the total reaction time used in the dry reforming reaction, thereby constituting a dry reforming catalyst using carbon dioxide.

[0024] According to a preferred embodiment of the present invention, the mixed catalytic component containing nickel and cobalt can be dispersed on the surface of the support in an amount of 0.3 to 4 wt% of the total weight of the catalyst.

[0025] According to a preferred embodiment of the present invention, the nickel content may be 0.5 times or more higher by weight than the cobalt content.

[0026] According to a preferred embodiment of the invention, nickel and cobalt may be present in a weight ratio of (1.01 to 4):1.

[0027] According to a preferred embodiment of the present invention, the catalyst mixture containing nickel and cobalt may be included in the form of being directly supported on the carrier.

[0028] According to a preferred embodiment of the present invention, the catalyst may further comprise Zr, Ti, Ce and noble metal-based components as co-catalysts.

[0029] According to a preferred embodiment of the present invention, the catalyst may contain two or more composite metals as co-catalysts.

[0030] According to a preferred embodiment of the invention, the reforming reaction using carbon dioxide as a reducing gas can be, for example, a dry reforming reaction or a combined reforming reaction, wherein carbon dioxide is used in excess, such as a methane-carbon dioxide reaction.

[0031] According to a preferred embodiment of the present invention, the co-catalyst may be present in an amount less than that of the main catalyst.

[0032] According to a preferred embodiment of the present invention, the noble metal-based component used in the co-catalyst may include one or more components selected from Pd, Pt, Rh, Ru, Os and Ir.

[0033] According to a preferred embodiment of the present invention, the content of the noble metal-based component as a co-catalyst can be 0.01 to 0.5 wt% based on the total weight of the active metal.

[0034] According to a preferred embodiment of the present invention, the content of one or more metals selected from Zr, Ti and Ce as co-catalysts can be 0.1 to 1.0 wt% based on the total weight of the active metals.

[0035] According to a preferred embodiment of the present invention, the catalyst may contain a specific surface area of ​​0.1 to 5 m². 2 / g carrier.

[0036] According to a preferred embodiment of the invention, the catalyst may contain a support with a water absorption rate of 15% to 55%.

[0037] According to a preferred embodiment of the present invention, the catalyst may contain one or more components selected from cordierite, SiC, Al2O3 and SiO2 as a support.

[0038] According to a preferred embodiment of the present invention, the reaction between methane and carbon dioxide can occur when the weight ratio of carbon dioxide to methane is 1.01 to 2.

[0039] According to a preferred embodiment of the present invention, depending on the ratio of carbon dioxide to methane, the catalyst can achieve a carbon dioxide gas conversion rate of 70% or higher at a reaction temperature of 800 to 1000°C.

[0040] According to a preferred embodiment of the present invention, depending on the ratio of carbon dioxide to methane, the catalyst can achieve a methane gas conversion rate of 50% or higher at a reaction temperature of 800 to 1000°C.

[0041] Beneficial effects The catalyst according to the present invention for producing syngas using carbon dioxide via a reducing gas reforming reaction has improved catalytic activity and stability by having a catalyst composition different from that of conventional catalysts.

[0042] Furthermore, the catalyst for producing syngas according to the present invention does not cause carbon buildup when used in a predetermined amount in the reforming reaction, thereby enabling long-term use and achieving excellent conversion rates.

[0043] The effects of this invention are not limited to those described above, but should be understood to cover all effects inferred from the detailed description or claims of this invention. Attached Figure Description

[0044] Figure 1 ( Figure 1 A, Figure 1 B) is a graph illustrating the results of measuring catalyst lifetime when using a dry reforming catalyst based on reducing gas and utilizing carbon dioxide, manufactured according to an embodiment of Experimental Example 1 of the present invention, for dry reforming with carbon dioxide and methane gas.

[0045] Figure 2 ( Figure 2 A, Figure 2 B) is a graph illustrating the experimental results of catalyst lifetime evaluation when the Ni:Co content ratio of the Ni-Co-based catalyst used as a dry reforming catalyst in Experimental Example 2 of the present invention is Ni:Co=3:Co=1 and Ni:Co=1:1.

[0046] Figure 3 This is a graph illustrating the results of an experiment evaluating the conversion rate based on the Ni:Co content ratio and reaction temperature of a Ni-Co-based catalyst used as a dry reforming catalyst in Experimental Example 3 according to the present invention.

[0047] Figure 4 This is a graph comparing the methane conversion over time obtained by using the catalysts of Example 1 and Example 4 and Comparative Example 1 in Experimental Example 4 of the present invention for excess dry reforming of carbon dioxide.

[0048] Figure 5 This is a graph comparing the change in carbon dioxide conversion rate over time obtained by using the catalysts of Example 1 and Example 4 and Comparative Example 1 in Experimental Example 4 according to the present invention for excess dry reforming of carbon dioxide.

[0049] Figure 6 is a graph comparing the conversion rates of methane and carbon dioxide obtained by excess dry reforming of carbon dioxide using the catalysts of Examples 1 and 4 and Comparative Example 1 in Experimental Example 4 according to the present invention, at the final reaction time. Detailed Implementation

[0050] The invention will now be described in more detail using the following embodiments.

[0051] The descriptions and figures herein are merely illustrative of the most preferred embodiments of the invention and do not represent the full scope of the invention. Therefore, it should be understood that various equivalents and modifications may exist at the time of filing. It should also be understood that the embodiments described herein are illustrative in all respects and not restrictive, and the scope of the invention is defined by the appended claims rather than the detailed description, and all changes or modifications to the meaning and scope of the claims and their equivalents should be interpreted as including within the scope of the invention.

[0052] The present invention relates to a novel dry reforming catalyst for the utilization of carbon dioxide based on reducing gas, which is configured to use a minimum amount of catalytically active components in order to significantly extend catalyst lifetime.

[0053] More specifically, the present invention relates to a catalyst for producing syngas using carbon dioxide via a reducing gas reforming reaction, and more specifically to a catalyst for producing syngas using carbon dioxide via a reducing gas reforming reaction, characterized in that the long-term catalyst stability is improved under carbon dioxide excess reaction conditions compared to typical reforming conditions where the reducing gas to carbon dioxide ratio is 1:1.

[0054] In this invention, reducing gas is defined as a reducing agent used to produce syngas by reducing carbon dioxide (CO2), and generally refers to a gaseous substance. Such reducing gases include hydrocarbons (such as methane, ethane, and propane, or mixtures thereof), or mixtures thereof. Examples of reducing gases may include mixtures containing CH4, CO2, H2, O2, and N2. Additionally, reducing gases can typically include carbon-containing biogas, industrial by-product gases generated from industrial activities, carbon-containing gas mixtures, greenhouse gases (such as methane or carbon dioxide), unreacted materials, by-products, and volatile organic compounds generated in a plant. Examples of biogas may include methane, ethane, propane, butane, alcohols, ketones, and aldehydes.

[0055] In this invention, the term "carbon reaction system" refers to a reaction system in which carbon reactions are involved in a reaction using a reducing gas in a dry reforming reaction utilizing carbon dioxide. As described above, the carbon reaction system of this invention generally includes a reaction in which carbon deposition occurs during a reforming reaction utilizing carbon dioxide. Therefore, the application of the dry reforming catalyst of this invention can be applied to dry reforming involving carbon dioxide utilization, carbon dioxide utilization based on reducing gas, carbon reaction systems, or carbon reaction systems based on reducing gas.

[0056] In this invention, the reforming reaction includes a process for converting reducing gas into syngas. In the context of reforming catalysts, the terms "for dry reforming" or "for dry reforming reaction" refer to a pure dry reforming reaction, as well as reactions in which dry reforming is applied or included, such as combined reforming reactions. Here, the dry reforming reaction is a concept relative to the wet reforming reaction and refers to a reaction in a substantially anhydrous reaction system. However, the reforming catalyst of this invention can also be applied to reactions involving dry reforming systems, such as combined reforming reactions.

[0057] Therefore, the present invention is characterized by a novel catalyst configuration for use in reforming reactions (such as dry reforming) for the production of syngas from gases (such as carbon dioxide or methane).

[0058] According to embodiments of the present invention, a composite catalyst containing nickel (Ni) and cobalt (Co) as catalytically active components is preferably used as a reforming catalyst.

[0059] The Ni-Co catalyst according to embodiments of the present invention can preferably be used as a catalyst in which the Ni content is greater than that of Co.

[0060] According to the present invention, the meaning of "Ni content is greater than Co" can include cases where the contents of Ni and Co are substantially the same, but the content of Ni is slightly greater than that of Co.

[0061] According to a preferred embodiment of the present invention, the nickel content may be 0.1 times higher by weight than the cobalt content, more preferably 0.5 times or more by weight.

[0062] According to a preferred embodiment of the invention, nickel and cobalt may be present in the following Ni:Co weight ratio: (1.01 to 4):1, or 1.1 to 4:1, preferably 1.5 to 4:1, more preferably 2.5 to 3.5:1, or 3:1, such that the Ni content is in excess. When the Ni component is in relatively excess within the above range, a significantly better catalyst lifetime extension effect can be expected compared to compositions in which the Ni content is not in such excess.

[0063] According to a preferred embodiment of the present invention, the content of the Ni-Co composite active component can be 0.3 to 4 wt%, or 0.5 to 4 wt%, preferably 0.7 to 3 wt%, or 0.7 to 2 wt%.

[0064] If the content of this active component is too low, the catalytic activity may be insignificant, resulting in low conversion rate. If the content is too high, rapid carbon deposition may occur, thereby shortening the catalyst life.

[0065] According to a preferred embodiment of the invention, in the case of a Ni-Co catalyst, the catalyst mixture containing nickel and cobalt can preferably be directly supported on a support without the need for a separate binder.

[0066] For example, a catalyst can be prepared in which nickel and cobalt are supported on a porous catalyst support, with a nickel content greater than that of cobalt, and a mixed catalytic component of nickel and cobalt dispersed and contained on the surface of the support, at a content of 0.5 to 4 wt% based on the total catalyst composition. The Ni-Co catalyst of the present invention can maintain a catalyst lifetime of 1500 hours or more, preferably 2000 hours or more, more preferably 3000 hours or more, 5000 hours or more, 10000 hours or more, or 20000 hours or more.

[0067] According to a preferred embodiment of the present invention, when using this catalyst for a dry reforming reaction, the CO2 gas conversion rate can be 70% or higher at 800 to 1000°C. However, the conversion rate increases when the Ni to Co content ratio in the catalyst composition is maintained within an optimal range, and the reaction temperature is maintained at a higher level within this range. For example, at 900 to 1000°C, the conversion rate can be 90% or higher, more preferably 95% or higher.

[0068] According to a preferred embodiment of the present invention, when using this catalyst for a dry reforming reaction, the CH4 gas conversion rate can be 50% or higher at 800 to 1000°C. However, the conversion rate increases when the Ni to Co content ratio in the catalyst composition is maintained within the optimal range, and the reaction temperature is maintained at a higher level within the aforementioned range. For example, at 900 to 1000°C, the conversion rate can be 85% or higher, more preferably 90% or higher.

[0069] According to a preferred embodiment of the present invention, in the case of a Ni-Co composite catalyst, the nickel hydrate or salt and cobalt hydrate or salt applied to the support can be used as catalyst precursors.

[0070] According to a preferred embodiment of the present invention, in order to prepare the catalyst, a method for manufacturing a catalyst for dry reforming of a carbon reaction system can be provided, the method comprising, for example, the following steps: preparing a porous support; preparing a nickel metal oxide precursor; preparing a cobalt metal oxide precursor; mixing the nickel metal oxide and the cobalt metal oxide such that the weight ratio of nickel to cobalt is (1.01 to 4):1, and supporting them on the porous support in an amount of 0.3 to 4 wt%; and drying the support on which the nickel metal oxide and the cobalt metal oxide are supported, and calcining the support at a temperature of 500°C or higher.

[0071] At this point, the carrier can be selected from one or more of the carriers listed above.

[0072] As a preferred example of the dry reforming catalyst according to the invention, the catalyst can be manufactured such that a mixed catalytic component of nickel and cobalt is supported on the porous catalyst support, wherein nickel and cobalt are directly supported on the support at a nickel:cobalt weight ratio of (1.01 to 4):1, and the content of the mixed catalytic component of nickel and cobalt is 0.3 to 4 wt% based on the total catalyst composition, thereby having a catalyst lifetime of 2000 hours or more based on the total reaction time used in the dry reforming reaction.

[0073] Therefore, the Ni-Co catalyst presented as an embodiment of the present invention can be effectively used for a long period of time as a dry reforming catalyst utilizing carbon dioxide, and is expected to be widely and economically applied in reducing gas-based dry reforming reactions.

[0074] Furthermore, according to a preferred embodiment of the present invention, the catalyst for reforming reaction of the present invention is characterized in that by further adding a co-catalyst to the nickel-cobalt-based active component, the catalytic activity and stability under reforming conditions with excess carbon dioxide can be improved.

[0075] According to a preferred embodiment of the present invention, the reforming reaction using carbon dioxide to reduce the gas can be, for example, a dry reforming reaction in which an excess of carbon dioxide is used, or a combined reforming reaction, such as a methane-carbon dioxide reaction.

[0076] According to a preferred embodiment of the present invention, when a co-catalyst is used, the content of the Ni-Co based main catalyst can be from 0.001 to 5 wt%. More preferably, the content of the Ni-Co based main catalyst can be from 0.1 to 4 wt%, 0.3 to 4 wt%, or 1 to 3 wt%. Furthermore, according to a preferred embodiment of the present invention, it is preferable that the Ni content in the Ni-Co based main catalyst is greater than that of Co; for example, a Ni:Co ratio of 1.01 to 5:1 is preferred, and a ratio of 2.5 to 3.5:1 is more preferred.

[0077] According to a preferred embodiment of the present invention, the co-catalyst may contain one or more components selected from Zr, Ti and Ce and noble metal-based components; more preferably, a composite metal containing two or more metals may be used.

[0078] According to a preferred embodiment of the present invention, the content of the noble metal-based component can be from 0.0001 to 1.5 wt% based on the total weight of the active metal components, and the content can be less than the content of the main catalyst.

[0079] According to a preferred embodiment of the present invention, the noble metal-based component used in the cocatalyst may comprise one or more components selected from Pd, Pt, Rh, Ru, Os, and Ir. More preferably, one or more components selected from Pd, Pt, Rh, and Ru may be used; most preferably, one or more of palladium or platinum may be used.

[0080] According to a preferred embodiment of the present invention, the content of the noble metal-based component as a co-catalyst may be 0.01 to 0.5 wt% based on the total weight of the active metal components. More preferably, the content of the noble metal-based component may be 0.01 to 0.3 wt%, more preferably 0.01 to 0.2 wt%, and most preferably 0.01 to 0.1 wt%.

[0081] According to a preferred embodiment of the invention, one or more metals selected from Zr, Ti, and Ce can be used as a co-catalyst, and the content of the co-catalyst component can be 0.1 to 1.0 wt% based on the total weight of the active metal components. More preferably, one or more components selected from Zr and Ti can be used. The content of such metal components used is preferably 0.1 to 0.8 wt%, and most preferably 0.1 to 0.5 wt%.

[0082] According to a preferred embodiment of the present invention, the catalyst can react with a specific surface area of ​​0.1 to 5 m². 2 Used together with a carrier of / g. Additionally, a carrier with a water absorption rate of 15 to 55% is preferred.

[0083] According to a preferred embodiment of the invention, the catalyst may use one or more components selected from cordierite, SiC, Al2O3, and SiO2 as a support. Typically, supports conventionally used for dry reforming catalysts can be used, but alumina-silica-based supports are particularly preferred.

[0084] According to a preferred embodiment of the present invention, an example of a method for manufacturing the catalyst described above for a reforming reaction will be described, and the method for manufacturing the reforming catalyst includes the following steps: preparing a support, such as a porous support; preparing a nickel metal oxide precursor; preparing a cobalt metal oxide precursor; mixing the nickel metal oxide and the cobalt metal oxide such that the weight ratio of nickel to cobalt is (1.01 to 4):1, and supporting them on the support in an amount of 0.3 to 4 wt%; and drying the support on which the nickel metal oxide and the cobalt metal oxide are supported, and calcining the support at a temperature of 500°C or higher.

[0085] Additionally, as an example of producing syngas using the catalyst for producing syngas according to the present invention, a method for producing syngas from carbon dioxide via a reforming reaction of reducing gas is provided, characterized in that methane and carbon dioxide are used as reactant gases, wherein carbon dioxide is used in excess, and a reforming reaction catalyst is applied to the reaction system of the reactant gases, the catalyst comprising nickel and cobalt, wherein the nickel content is greater than the cobalt content, more preferably, Ni-Co is used as the main catalyst, and one or more metals selected from Zr, Ti and Ce and noble metal-based components are used as co-catalysts, wherein the amount of the main catalyst is greater than the amount of the co-catalyst, for carrying out the reforming reaction of reducing gas using carbon dioxide.

[0086] According to a preferred embodiment of the invention, the reaction between the reducing gas and carbon dioxide is preferably carried out under conditions in which carbon dioxide is in excess, for example, carbon dioxide and the reducing gas can react when the weight ratio of carbon dioxide to reducing gas is 1.01 to 2. If carbon dioxide is insufficient under these reaction conditions, the oxidant is insufficient relative to the reducing agent, and therefore other reactions (such as methane decomposition) may occur besides the reforming reaction. Furthermore, the pressure inside the reactor may increase due to rapid carbon deposition caused by the decomposition of the reducing gas, making the reaction difficult to proceed or causing it to terminate. On the other hand, under reaction conditions in which carbon dioxide is in excess, unlike the insufficient conditions, the excess oxidant will rapidly oxidize the active metal component, potentially leading to catalyst deactivation and making it difficult to guarantee long-term stability.

[0087] According to the present invention, unlike conventional catalysts, the catalyst of the present invention is newly configured as a reforming catalyst particularly suitable for dry reforming or dry-wet combined reforming, and by using a co-catalyst with specific components, the excellent long-term stability of the catalyst can be ensured.

[0088] According to a preferred embodiment of the present invention, when added as a co-catalyst to the reforming catalyst used in the excess carbon dioxide reforming reaction of the present invention, the co-catalyst exhibits excellent reduction characteristics even under strongly oxidizing reaction conditions (rather than under the weakly reducing reaction conditions typical of general reforming reactions), thereby inhibiting the oxidation of the active metal. Therefore, although the components that can be used as co-catalysts each have different characteristics, it is not easy to select a component that exhibits excellent thermal stability even at high temperatures, heat resistance, does not participate in coking during the reaction, induces strong interactions between the active metal and the support, protects the active metal from sintering, and inhibits oxidation, thereby stably maintaining excellent catalytic activity. Therefore, considering the main catalyst components of the present invention, it is preferable to select the above-mentioned specific components as co-catalyst components capable of stably maintaining catalytic activity.

[0089] In this invention, selective use of this co-catalyst can further significantly improve the catalytic activity of Ni-Co catalyst as the main catalyst in the reforming reaction of reducing gas with excess carbon dioxide, thereby maintaining a high conversion rate and ensuring long-term catalyst stability in the reforming reaction, so that a synergistic effect can be expected.

[0090] Furthermore, according to the present invention, for example, under conditions in which carbon dioxide is used in excess, excellent conversion effects can be achieved by utilizing carbon dioxide to reform the reducing gas and by using the catalyst described above for producing syngas through the reforming reaction.

[0091] Therefore, the present invention includes a method for producing syngas by reforming carbon-based reducing gas, wherein, when the reducing gas is reformed with excess carbon dioxide, Ni-Co having the above composition is used as a main catalyst, and one or more metals selected from Zr, Ti and Ce and noble metal-based components are used as co-catalysts, wherein the amount of the main catalyst is greater than the amount of the co-catalyst, to carry out the reforming reaction.

[0092] According to the present invention, in the process of producing syngas through such reforming reaction, the catalyst of the present invention also uses a co-catalyst and controls a series of configurations, such as the amount of reducing gas used relative to carbon dioxide, the amount of catalyst components used, and the application of the co-catalyst, thereby suppressing carbon deposition and imparting heat resistance properties, extending the catalyst lifespan from 2000 hours or more to tens of thousands of hours, and significantly improving catalytic activity while maintaining catalyst stability, thereby achieving excellent conversion results.

[0093] The present invention will be described in detail below based on specific embodiments, but the present invention is not limited to the embodiments illustrated herein.

[0094] [Example 1] Commercially available alumina-silica-based oxide was used as the support for the reforming catalyst without any additional treatment. Before loading the active component, a small amount (up to 2 wt%) of immobilizing additive (alumina sol) was applied to the support, and the support was heat-treated at 500°C for 4 hours to immobilize the additive. The catalyst was prepared by fixing the nickel to cobalt ratio at 3:1 and setting the active component content to 1.5 wt%. Deionized water was used as the solvent to prepare an active metal precursor solution in which palladium nitrate was dissolved at 0.05 wt% together with a nickel-cobalt precursor in nitrate form, and the active component was supported on the catalyst by a wet impregnation method. The catalyst with the active component supported was calcined at 500°C for 4 hours to prepare the catalyst of Example 1.

[0095] [Example 2] Catalyst 2 was prepared in the same manner as in Example 1, but with the palladium content increased to 0.2 wt%.

[0096] [Example 3] Catalyst 3 was prepared in the same manner as in Example 1, but with the platinum content increased to 0.05 wt%.

[0097] [Example 4] Commercially available alumina-silica-based oxide was used as the support for the reforming catalyst without any additional heat treatment. The catalyst was prepared by maintaining a nickel to cobalt ratio of 3:1 and setting the active component content to 1.5 wt%. Deionized water was used as a solvent to prepare a precursor solution in which palladium nitrate (0.05 wt%) and zirconium oxychloride (0.25 wt%) were dissolved together with a nickel-cobalt precursor in nitrate form, and the active component was supported on the catalyst by a wet impregnation method. The catalyst with the active component was calcined at 500°C for 4 hours to prepare the catalyst of Example 4.

[0098] [Example 5] The catalyst of Example 5 was prepared in the same manner as in Example 4, but the zirconium content was increased to 0.5 wt%.

[0099] [Example 6] The catalyst of Example 6 was prepared in the same manner as in Example 4, but the titanium content was increased to 0.25 wt%.

[0100] [Comparative Example 1] The catalytically active components were supported on a carrier without the use of fixed additives. A binary catalyst was prepared by a wet impregnation method, with the nickel-cobalt content fixed at 1.5 wt% and the nickel to cobalt ratio set at 3:1. The supported catalyst was calcined at 500°C for 4 hours to prepare the catalyst of Comparative Example 1.

[0101] [Comparative Example 2] The active component content was fixed at 1.5 wt%. A precursor solution containing dissolved cobalt nitrate and palladium was prepared, and the active metal component was supported by a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare the catalyst of Comparative Example 2.

[0102] [Comparative Example 3] The active component content was fixed at 1.5 wt%. A precursor solution containing dissolved cobalt nitrate and zirconium oxychloride was prepared, and the active metal component was supported by a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare the catalyst of Comparative Example 3.

[0103] [Comparative Example 4] The active component content was fixed at 1.5 wt%. A precursor solution containing dissolved nickel nitrate and palladium was prepared, and the active metal component was supported by a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare the catalyst of Comparative Example 4.

[0104] [Comparative Example 5] The active component content was fixed at 1.5 wt%. A precursor solution containing dissolved nickel nitrate and zirconium oxychloride was prepared, and the active metal component was supported by a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare the catalyst of Comparative Example 5.

[0105] [Experimental Example 1] A dry reforming catalyst was prepared using a Ni and Co composite active component supported on a porous support, with the mixing ratio of Ni and Co varying and the total content of the active component adjusted to 2 wt%. A continuous dry reforming reaction was carried out using carbon dioxide and methane gas under the same conditions as in Example 1, and the conversion rates of the reaction gases (CO2 and CH4) were measured at different reaction temperatures.

[0106] The results are presented in comparative form. Figure 1 middle( Figure 1 A is CH4. Figure 1 B is CO2). Figure 1 The figures and related data illustrate the results of conversion evaluation experiments based on the Ni to Co content ratio of a Ni-Co-based catalyst used as a dry reforming catalyst according to one embodiment of the present invention.

[0107] These experimental results indicate that, depending on the Ni-Co content ratio, the initial properties are similar (see [link]). Figure 1 Regarding reaction durability, the durability improves with increasing Ni content (see...). Figure 2 A and Figure 2 B).

[0108] [Experimental Example 2] Dry reforming catalysts were prepared using a Ni and Co composite active component supported on a porous support, with the mixing ratio of Ni and Co varied and the total content of the active component adjusted to 2 wt%. A continuous dry reforming reaction was carried out using carbon dioxide and methane gas under the same conditions as in Example 1, and the catalyst lifetime (defined as the available operating time of the catalyst) was measured.

[0109] The results are shown in Figure 2 ( Figure 2 A and Figure 2 B) in. Figure 2 This is a graph illustrating the results of a catalyst lifetime evaluation experiment using a Ni-Co based catalyst as an embodiment of the dry reforming catalyst according to the present invention, wherein the Ni:Co content ratio is 3:1. Figure 2 A), wherein the Ni:Co content ratio is 1:1 ( Figure 2 B).

[0110] Based on these results, the catalyst lifetime was confirmed to be approximately 6000 hours or longer in the case of Ni:Co = 3:1, and approximately 1700 hours in the case of Ni:Co = 1:1.

[0111] Therefore, in the above embodiments, it was confirmed that when the Ni content is higher than that of Co, a significantly better catalyst lifetime is exhibited compared to the case where the Ni and Co contents are the same. However, even when using Ni and Co in substantially the same amounts, a catalyst lifetime significantly better than that of conventional catalysts can be achieved. Therefore, since the excellent effect is exhibited even when using Ni and Co in substantially the same amounts, it is confirmed that a composition where the Ni content is slightly higher than that of Co also provides an excellent effect of long catalyst lifetime.

[0112] [Experiment Example 3] The dry reforming catalysts of Examples 4 and 5 were prepared by adjusting the content of catalytically active components (Co and Ni) on a porous support with a small amount (up to 2 wt%) of fixed additives (alumina sol) attached to it to 0.5 to 3 wt%. A continuous dry reforming reaction was carried out at a reaction temperature of 900 °C using carbon dioxide and methane gas in a 1:1 ratio, and the catalyst lifetime (defined as the available operating time of the catalyst) was measured.

[0113] The results are shown in Figure 3 middle.

[0114] according to Figure 3The experimental results shown confirm that the catalyst's durability is 6,000 hours or longer under ideal conditions, demonstrating an ultra-long lifespan that is approximately 10 to 20 times longer than the maximum lifespan of conventional catalysts.

[0115] [Experiment Example 4] To evaluate the performance of the catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 5, a reforming reaction of methane and carbon dioxide was carried out according to the following method, and the results are shown in... Figure 4 middle.

[0116] The reforming reaction of the catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was evaluated in a fixed-bed reactor equipped with an external heating system, wherein the reactor was a tubular quartz reactor with an outer diameter of 1 / 2 inch. Prior to the reaction, the catalysts prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were reduced with 5% H2-Ar at 900°C for 1 hour. The reaction was carried out by using methane and carbon dioxide reactant gases at a ratio of 1:1.7 and for 1000 to 3000 h. -1 The air velocity is supplied to the reactor to carry out the catalytic reaction. The catalytic reaction is carried out at atmospheric pressure and at a temperature of 800°C to 1000°C. The gases emitted after the reaction are analyzed using a gas chromatography system equipped with a thermal conductivity detector.

[0117] Under the above reaction conditions, the reaction results obtained by using the catalysts prepared in the Examples and Comparative Examples are shown in Table 1.

[0118] [Table 1]

[0119] Under the above reaction conditions, the methane and carbon dioxide conversion rates of the catalysts used in Examples 1 and 4 and Comparative Example 1 were respectively at [values ​​missing]. Figure 4 ( Figure 4 A and Figure 4 The comparison is explained in section B).

[0120] like Figure 4 As shown, the catalyst in Example 4 exhibited the highest methane ( Figure 4 A) and carbon dioxide ( Figure 4 B) Conversion rate and stable catalytic activity during the reforming reaction at 1800 hours. The catalyst of Example 1 exhibited similar catalytic activity to the catalyst of Example 4 and maintained stable reaction activity for 500 hours, but the catalytic activity gradually decreased after 500 hours of reaction. In addition, the catalyst of Example 2 exhibited similar activity to the catalyst of Example 1, but lower catalyst stability was observed compared with the catalyst of Example 1. The catalyst of Example 3 exhibited a similar trend in reaction activity and stability as that of Example 1.

[0121] Furthermore, the catalyst of Example 5 exhibited similar activity to that of Example 4, but lower stability was observed compared to the catalyst of Example 4. The catalyst of Example 6 exhibited similar reactivity and stability trends to that of Example 4.

[0122] Meanwhile, the catalyst of Comparative Example 1 exhibited similar activity to the catalysts of Examples 1 to 4, but its catalytic activity decreased rapidly after 35 hours of reaction.

[0123] The reforming reaction experiments conducted on the catalysts of Examples 1 to 6 and the comparative examples confirmed that, under the reforming conditions of excess carbon dioxide reducing gas, the catalytic activity and stability proposed in this invention are significantly affected by the addition of noble metal-based co-catalysts and zirconium-based co-catalysts, and exhibit excellent effects at specific contents of the co-catalysts.

[0124] In these experimental results, the reforming reactions of the catalysts of Comparative Examples 2 to 5 were studied under the reaction conditions of Experimental Example 1, wherein noble metal-based components and zirconium-based components were added to a single metal catalyst with nickel or cobalt as the main active metal. The results are shown in Table 1.

[0125] As confirmed in Table 1, the catalysts of Comparative Example 2 and Comparative Example 3 exhibited low activity and low stability under reaction conditions with excess carbon dioxide, even when palladium or zirconium was added as a co-catalyst to the cobalt single-metal catalyst.

[0126] Furthermore, these experimental results explain why, under an oxidizing atmosphere caused by excess carbon dioxide, the oxidation of cobalt, as the active component, significantly reduces both catalytic activity and stability.

[0127] Furthermore, the catalysts proposed in Comparative Examples 4 and 5 exhibited higher catalytic activity and stability than those in Comparative Examples 2 and 3, but it was observed that their activity and stability were significantly lower than those of the multi-component composite oxide catalysts proposed in this invention.

[0128] In the above experiments, it was confirmed that under reforming reaction conditions in which the ratio of methane to carbon dioxide was 1:1.1 to 2, the catalysts of Comparative Examples 1 to 5 exhibited improved activity and stability by adding a noble metal-based co-catalyst or by additionally incorporating one or more co-catalysts selected from Zr, Ti and Ce.

[0129] However, under the carbon dioxide excess reducing gas reforming conditions proposed in this invention, i.e., reforming conditions where mild oxidation reactions predominate, the oxidation of active metals such as nickel and cobalt alone is insufficient to ensure catalytic activity and stability. In particular, under reforming conditions where the oxidizing atmosphere predominates, the reactivity of cobalt decreases rapidly due to its relatively faster metal oxidation compared to nickel.

[0130] The above experiments confirm that, in dry reforming experiments for the efficient removal of carbon dioxide from reducing gas, the Ni-Co catalyst composition according to the present invention, used under specific conditions, exhibits excellent conversion and lifetime extension effects in producing syngas through the reducing gas reforming reaction utilizing carbon dioxide in dry reforming experiments. Furthermore, due to the use of a co-catalyst, this catalytic system has been confirmed to exhibit significantly better long-term stability compared to conventional reforming catalysts, thus providing an effective catalytic system.

Claims

1. A catalyst for producing syngas from carbon dioxide via a reforming reaction of reducing gas, said catalyst comprising a catalyst support on which a mixed catalytic component containing nickel and cobalt is supported, wherein the nickel content is greater than the cobalt content, and the lifetime of said catalyst is 1500 hours or more based on the total reaction time used in the dry reforming reaction.

2. The catalyst according to claim 1, wherein the mixed catalytic component containing nickel and cobalt is dispersed on the surface of the support in an amount of 0.3 wt% to 4 wt% of the total weight of the catalyst.

3. The catalyst according to claim 1, wherein nickel and cobalt are present in a weight ratio of (1.01 to 4):

1.

4. The catalyst according to claim 1, wherein the reforming reaction of the reducing gas is a methane-carbon dioxide reaction, wherein carbon dioxide is used in excess.

5. The catalyst according to claim 1, wherein the reforming reaction of the reducing gas is a dry reforming reaction or a combined reforming reaction including a dry reforming reaction.

6. The catalyst according to any one of claims 1 to 5, wherein the catalyst further comprises one or more components selected from Zr, Ti and Ce and noble metal-based components as a co-catalyst.

7. The catalyst according to claim 6, wherein the content of the co-catalyst is from 0.001 wt% to 1.5 wt%, and is present in a content less than that of the main catalyst.

8. The catalyst according to claim 6, wherein the noble metal-based component used in the co-catalyst comprises one or more components selected from Pd, Pt, Rh, Ru, Os and Ir.

9. The catalyst according to claim 6, wherein the co-catalyst comprises one or more metals selected from Zr, Ti and Ce, and one or more noble metals selected from Pd, Pt, Rh, Ru, Os and Ir, wherein the noble metals are present in an amount of 0.01 wt% to 1.0 wt%.

Images