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 a reforming reaction of a reducing gas using carbon dioxide, and more specifically to a catalyst for producing a synthesis gas, by which, when a composite catalyst comprising nickel-cobalt, used for reforming reducing gas using carbon dioxide, is newly configured and used in a reforming reaction, excellent catalytic activity and stability are achieved, and an excellent conversion rate of a carbon-based reducing gas is gained.

Description

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

[0001] The present invention relates to a catalyst for producing synthesis gas by a reforming reaction of a reducing gas using carbon dioxide, and more specifically, to a catalyst for producing synthesis gas having excellent catalytic activity and stability and an excellent conversion rate of reducing gas when used in a reforming reaction using carbon dioxide.

[0002] Unless otherwise indicated herein, the matters described in this section are not prior art to the claims of this application and their inclusion in this section is not intended to be admitted as prior art.

[0003] Recently, energy issues have become a major social issue, and on the other hand, excessive greenhouse gas emissions related to carbon dioxide emissions are emerging as a serious environmental problem.

[0004] Recognizing the urgent need to develop and utilize renewable energy sources that can achieve sustainable growth to ensure energy security both domestically and internationally, renewable energy sources are being expanded, and various technologies are being developed to address environmental issues, such as carbon dioxide capture and utilization.

[0005] Our country is recognized as a major greenhouse gas emitter in the world, and international pressure to reduce greenhouse gas emissions is increasing.

[0006] Hydrogen energy is being utilized as a future clean energy source that can simultaneously solve environmental problems such as global warming and the problem of energy dependence, and securing technology to utilize carbon dioxide as a cyclical carbon resource is becoming an important research topic.

[0007] In general, there are methods for producing synthesis gas composed of hydrogen and carbon monoxide, including methods using fossil fuels such as natural gas. Among these synthesis gas production methods, from an economic perspective, it is advantageous to use biomass such as carbon dioxide and methane gas and utilize renewable energy.

[0008] As a method for producing synthesis gas from existing biogas, methods such as dry reforming, wet reforming, or combined reforming, which are summarized by the following reaction formula, are known.

[0009] Dry reforming: CO2+ CH4→ 2CO + 2H2(ΔH=247 kJ / mol)

[0010] Wet reforming: H2O + CH4→ 3H2+ CO (ΔH=226 kJ / mol)

[0011] Complex reforming: CO2+ 3CH4+ 2H2O → 4CO + 8H2 (ΔH=712 kJ / mol)

[0012] Among the reforming reactions using the above-mentioned reducing gases, dry reforming is a synthesis gas production technology that can use the largest amount of CO2 (greenhouse gas) as a raw material among catalytic reforming technologies, and is receiving worldwide attention for securing the technology due to its high greenhouse gas reduction effect.

[0013] In particular, the dry reforming reaction requires a higher proportion of CO2 for chemical product production than other reforming reactions and has a high impact on greenhouse gas reduction, so efforts are being made to secure excellent reaction technology.

[0014] However, these dry reforming reactions utilize catalysts to carry out the reaction. Dry reforming (DRM) technology, which can reduce greenhouse gases, suffers from a critical drawback: short catalyst lifespan, making commercialization difficult. In particular, DRM, which utilizes the largest amount of carbon dioxide as a reactant to achieve greenhouse gas reduction, faces significant technical barriers, including harsh high-temperature reaction conditions and a short catalyst lifespan due to carbon deposition.

[0015] In this way, existing dry reforming catalysts have been continuously developed for the past 100 years because they can use CO2 as a raw material, but they still have the problem of extremely limited lifespan due to catalyst deactivation caused by various reasons and damage to the catalyst molded body caused by carbon deposition.

[0016] Therefore, although various studies have been proposed to extend the service life of catalysts, especially in dry reforming reactions, there is a lack of technological approaches other than extending the service life by forming a specific catalyst composition.

[0017] As a catalyst for a conventional reforming reaction, Korean Patent Registration No. 10-2194440 proposes a catalyst for biogas dry reforming that includes a metal oxide support containing a hydroxyl group on the catalyst surface and one or more active substances selected from nickel (Ni), cobalt (Co), ruthenium (Ru), palladium (Pd), iridium (Ir), platinum (Pt), and rhodium (Rh), and is proposed to have excellent catalytic activity and long-term stability.

[0018] However, although these existing catalysts for reducing gas reforming using carbon dioxide are pursuing long-term use, they have reported a catalyst life of less than 1,000 hours at most, and thus, no technology has been proposed to ensure sufficient catalyst life.

[0019] Therefore, there is an urgent need to develop a technology to improve the composition of the catalyst used to produce synthesis gas by reforming reducing gas with carbon dioxide, thereby increasing the efficiency of synthesis gas production.

[0020] The present invention aims to improve the problems of the prior art as described above, and to provide a catalyst for producing synthesis gas that improves the reforming efficiency when various reducing gases are reformed using carbon dioxide, and in particular, can be used for a long period of time without carbon deposition.

[0021] In order to solve these existing problems, the present invention was completed after conducting various studies on the characteristics and efficacy of catalyst active ingredients.

[0022] Therefore, the purpose of the present invention is to provide a Ni-Co catalyst for reducing gas reforming, which has a significantly longer catalyst life compared to existing proposed catalyst technologies because carbon deposition hardly occurs.

[0023] Another object of the present invention is to provide a catalyst effective in producing synthesis gas by reforming a reducing gas using carbon dioxide by newly configuring the composition of a Ni-Co catalyst composition.

[0024] Another object of the present invention is to provide a catalyst for producing synthesis gas, which has the characteristics of significantly long catalyst life and excellent conversion rate by suppressing carbon deposition during the process of reforming reducing gas using carbon dioxide.

[0025] The purpose of the present invention is not limited to the above-mentioned purpose, and should be understood to include all purposes that can be inferred from the composition of the invention described in the detailed description or claims of the present invention, or all purposes that can be achieved by the description or technical idea of ​​the present invention.

[0026] In order to solve the above-described problem of the present invention, the present invention can configure a catalyst for a reforming reaction of a reducing gas using carbon dioxide, wherein a mixed catalyst component including nickel and cobalt is supported on a catalyst support, nickel is contained in an excess amount compared to cobalt, and a catalyst life is 1,500 hours or more based on the total reaction time used in the dry reforming reaction.

[0027] According to a preferred embodiment of the present invention, a mixed catalyst component including nickel and cobalt can be dispersed and contained on the surface of a support at 0.3 to 4 wt% of the total catalyst composition.

[0028] According to a preferred embodiment of the present invention, the nickel may be contained in an excess amount of 0.5 times or more by weight compared to cobalt.

[0029] According to a preferred embodiment of the present invention, the nickel and cobalt may be contained in a weight ratio of (1.01 to 4): 1.

[0030] According to a preferred embodiment of the present invention, the catalyst mixture containing nickel and cobalt may be included in a form directly supported on a support.

[0031] According to a preferred embodiment of the present invention, the catalyst may additionally include Zr, Ti, Ce and noble metal components as cocatalysts.

[0032] According to a preferred embodiment of the present invention, two or more composite metals may be included as a cocatalyst.

[0033] According to a preferred embodiment of the present invention, the reforming reaction of the reducing gas using the carbon dioxide may be, for example, a dry reforming or a combined reforming reaction in which carbon dioxide is used in excess as a reaction between methane and carbon dioxide.

[0034] According to a preferred embodiment of the present invention, the cocatalyst may be contained in a smaller amount than the main catalyst.

[0035] According to a preferred embodiment of the present invention, the noble metal component used in the cocatalyst may contain at least one component selected from among Pd, Pt, Rh, Ru, Os, and Ir.

[0036] According to a preferred embodiment of the present invention, the noble metal component as a cocatalyst may be contained in an amount of 0.01 to 0.5 wt% based on the total weight of the active metal.

[0037] According to a preferred embodiment of the present invention, one or more metals selected from Zr, Ti, and Ce as a cocatalyst may be contained in an amount of 0.1 to 1.0 wt% based on the total weight of the active metal.

[0038] According to a preferred embodiment of the present invention, the catalyst may be used as a support having a specific surface area of ​​0.1 to 5 m2 / g.

[0039] According to a preferred embodiment of the present invention, the catalyst may be used as a support having a moisture absorption rate of 15 to 55%.

[0040] According to a preferred embodiment of the present invention, the catalyst may use at least one of cordierite, SiC, Al2O3, and SiO2 as a support.

[0041] According to a preferred embodiment of the present invention, the methane and carbon dioxide reaction can be carried out at a weight ratio of carbon dioxide / methane of 1.01 to 2.

[0042] According to a preferred embodiment of the present invention, the catalyst can have a carbon dioxide gas conversion rate of 70% or more depending on the carbon dioxide / methane ratio at a reaction temperature of 800 to 1,000°C.

[0043] According to a preferred embodiment of the present invention, the catalyst can have a methane gas conversion rate of 50% or more depending on the ratio of carbon dioxide / methane at a reaction temperature of 800 to 1,000°C.

[0044] The catalyst for producing synthesis gas by reforming a reducing gas using carbon dioxide according to the present invention can improve the activity and stability of the catalyst by differentiating the composition of catalyst components from existing ones.

[0045] In addition, the catalyst for producing synthesis gas of the present invention does not cause carbon deposition when used in a predetermined amount in a reforming reaction, so it can be used for a long period of time and has an excellent conversion rate.

[0046] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0047] Figure 1 (Figure 1A, Figure 1B) is a drawing showing the results of measuring the catalyst life when dry reforming using carbon dioxide and methane gas is performed using a catalyst for dry reforming using carbon dioxide using a reducing gas-based carbon dioxide manufactured by the method of one embodiment in Experimental Example 1 of the present invention.

[0048] FIG. 2 (FIG. 2A, FIG. 2B) is a graph showing the results of a catalyst life evaluation experiment for a case where the Ni and Co content ratio of a Ni-Co-based catalyst applied as an example of a catalyst for dry reforming in Experimental Example 2 according to the present invention is Ni:Co=3:1 and a case where the Ni and Co content ratio is Ni:Co=1:1.

[0049] Figure 3 is a graph showing the results of an experiment evaluating the conversion rate according to the Ni and Co content ratio and reaction temperature of a Ni-Co catalyst applied as an example of a catalyst for dry reforming in an experiment according to the present invention.

[0050] Figure 4 is a graph comparing the conversion rate of methane over the course of reaction time, which was obtained as a result of performing a dry reforming reaction with excess carbon dioxide using a catalyst according to Examples 1 and 4 and Comparative Example 1 in Experiment 4 of the present invention.

[0051] Figure 5 is a graph comparing the conversion rate of carbon dioxide over the course of reaction time, which was obtained as a result of performing a dry reforming reaction with excess carbon dioxide using a catalyst according to Examples 1 and 4 and Comparative Example 1 in Experiment 4 of the present invention.

[0052] Figure 6 is a graph comparing the conversion rates of methane and carbon dioxide according to the final reaction time, which was obtained as a result of performing a dry reforming reaction with excess carbon dioxide using a catalyst according to Examples 1 and 4 and Comparative Example 1 in the experiment of the present invention.

[0053] Hereinafter, the present invention will be described in more detail as an embodiment.

[0054] The descriptions and drawings described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive, and the scope of the present invention is indicated by the claims that follow rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention.

[0055] The present invention relates to a new concept dry reforming catalyst that can significantly extend the life of a catalyst by configuring a catalyst using a minimum of catalytically active components in a dry reforming catalyst utilizing carbon dioxide based on a reducing gas.

[0056] As a more specific example, the present invention relates to a catalyst for producing synthesis gas by reforming a reducing gas using carbon dioxide, and preferably, to a catalyst for producing synthesis gas by reforming a reducing gas using carbon dioxide, which is characterized by an improvement in long-term stability of the catalyst under reaction conditions with excess carbon dioxide, rather than a general reforming reaction in which the ratio of reducing gas to carbon dioxide is 1:1.

[0057] In the present invention, the reducing gas is defined as a reducing agent, such as one that reduces CO2 to produce synthesis gas, and mostly refers to a gaseous substance. Such reducing gases include, for example, hydrocarbons such as methane, ethane, and propane, or mixtures thereof, or compounds in which these are mixed. Examples of such reducing gases may include mixtures of CH4, CO2, H2, O2, N2, etc. In addition, reducing gases may typically include carbonaceous biogas, industrial gases produced as by-products from industrial activities, carbonaceous mixed gases, greenhouse gases such as methane or carbon dioxide, unreacted products, by-products, and volatile organic compounds generated in factories. Examples of biogases among these may include methane, ethane, propane, butane, alcohols, ketones, and aldehydes.

[0058] In the present invention, the carbon reaction system refers to a reaction system in which a carbon reaction is included in a reaction using a reducing gas used in dry reforming utilizing carbon dioxide. In the carbon reaction system of the present invention, since a carbon reaction is included in the carbon dioxide-utilizing reforming reaction process involving the above-mentioned reducing gas, a reaction in which carbon deposition typically occurs during the reaction process is included. Therefore, the application of the dry reforming catalyst of the present invention includes that it can be applied to dry reforming such as carbon dioxide utilization, reducing gas-based carbon dioxide utilization, carbon reaction system, or reducing gas-based carbon reaction system.

[0059] In the present invention, the reforming reaction includes a process of converting reducing gas into synthesis gas. Here, among the catalysts for reforming reactions, the term "for dry reforming" or "for dry reforming reaction" refers to a pure dry reforming reaction, which includes a reaction in which some dry reforming is applied or included, such as a complex reforming reaction using water. Here, the dry reforming reaction is a relative concept of the wet reforming reaction, and refers to a reaction in a reaction system that does not substantially contain water. However, the reforming catalyst of the present invention can also be applied to reactions that include a dry reforming system, such as a complex reforming reaction.

[0060] Therefore, the present invention features a novel composition of a catalyst used in a reforming reaction, such as dry reforming, for producing synthesis gas based on gases such as carbon dioxide or methane.

[0061] According to one embodiment of the present invention, a composite catalyst including nickel (Ni) and cobalt (Co) as active components of the catalyst can be preferably used as a catalyst for reforming.

[0062] The Ni-Co catalyst according to one embodiment of the present invention can preferably be applied as a catalyst containing Ni in excess of Co.

[0063] According to the present invention, the meaning of Ni being contained in excess compared to Co may include a case where the content levels are substantially the same, but Ni is contained in a trace amount more than Co.

[0064] According to a preferred embodiment of the present invention, the nickel may be contained in an amount of 0.1 times greater than cobalt, preferably 0.5 times greater than cobalt.

[0065] According to a preferred embodiment of the present invention, the nickel and cobalt may be contained in excess in a weight ratio of 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. In the case where the Ni component is contained in a relatively excessive amount as in the above-mentioned range, a significantly superior life extension effect can be expected compared to a composition where the Ni component is not contained in excess.

[0066] According to a preferred embodiment of the present invention, the Ni-Co composite active ingredient may be contained in an amount of 0.3 to 4 wt% or 0.5 to 4 wt%, more preferably 0.7 to 3 wt% or 0.7 to 2 wt%.

[0067] If the content of the active ingredient is too low, the catalytic effect will be minimal, resulting in a low conversion rate. If it is used in excessive amounts, carbon deposition will occur rapidly, shortening the life of the catalyst.

[0068] According to a preferred embodiment of the present invention, in the case of a Ni-Co catalyst, it may be preferable that the catalyst mixture component including nickel and cobalt is supported directly on the support without a separate adhesive.

[0069] For example, a porous catalyst support may be manufactured in which nickel and cobalt are supported, nickel is contained in an excess amount compared to cobalt, and a mixed catalyst component of nickel and cobalt is dispersed and contained on the surface of the support at 0.5 to 4 wt% of the total catalyst composition. The Ni-Co catalyst of the present invention may have a catalyst life of 1,500 hours or more, preferably 2,000 hours or more, and more preferably 3,000 hours or more, 5,000 hours or more, 10,000 hours or more, or 20,000 hours or more.

[0070] According to a preferred embodiment of the present invention, when performing a dry reforming reaction using the catalyst, the CO2 gas conversion rate at 800 to 1,000°C can be 70% or more. However, the conversion rate increases as the content ratio of Ni and Co in the composition of the catalyst is maintained within the most preferable range of the above range and the reaction temperature is maintained higher within the above range. For example, at 900 to 1,000°C, the conversion rate can be maintained at 90% or more, more preferably 95% or more.

[0071] According to a preferred embodiment of the present invention, when performing a dry reforming reaction using the catalyst, the CH4 gas conversion rate at 800 to 1,000°C can be 50% or more. However, the conversion rate increases as the content ratio of Ni and Co in the composition of the catalyst is maintained within the most preferable range of the above range and the reaction temperature is maintained higher within the above range. For example, at 900 to 1,000°C, the conversion rate can be maintained at 85% or more, more preferably 90% or more.

[0072] According to a preferred embodiment of the present invention, in the case of the Ni-Co composite catalyst, Ni hydrate or salt and Co hydrate or salt applied to the support can be used as precursors of the catalyst.

[0073] According to a preferred embodiment of the present invention, in order to manufacture the catalyst, a process for dry reforming of a carbon reaction system can be manufactured, including, for example, a step of preparing a porous support; a step of preparing a nickel metal oxide precursor; a step of preparing a cobalt metal oxide precursor; a step of mixing the nickel metal oxide and the cobalt metal oxide so that the weight ratio of nickel:cobalt is 1.01 to 4; 1 and supporting the porous support so that the amount is 0.3 to 4 wt%; and a step of drying the support on which the nickel metal oxide and the cobalt metal oxide are supported and calcining it at a temperature of 500°C or higher.

[0074] The support used at this time may be one or more of those listed above.

[0075] As a preferred example of a catalyst for dry reforming according to the present invention, a mixed catalyst component of nickel and cobalt is supported on a porous catalyst support, wherein nickel:cobalt is directly supported on the support at a weight ratio of 1.01 to 4:1, the mixed catalyst component of nickel and cobalt is contained at 0.3 to 4 wt% of the total catalyst composition, and the catalyst can be manufactured to have a lifespan of 2,000 hours or more based on the total reaction time used in the dry reforming reaction.

[0076] Therefore, the Ni-Co catalyst presented as an embodiment of the present invention is very effective as a catalyst for dry reforming utilizing carbon dioxide and can be used for a long period of time, and is therefore expected to be widely and very economically usable in a dry reforming reaction based on reducing gas.

[0077] Meanwhile, according to a preferred embodiment of the present invention, the catalyst for reforming reaction of the present invention is characterized by a catalyst capable of improving the activity and stability of the catalyst under carbon dioxide excess reforming reaction conditions by additionally adding a cocatalyst to the nickel-cobalt active component.

[0078] According to a preferred embodiment of the present invention, the reforming reaction of the reducing gas using the carbon dioxide may be, for example, a dry reforming or a combined reforming reaction in which carbon dioxide is used in excess as a reaction between methane and carbon dioxide.

[0079] According to a preferred embodiment of the present invention, when the cocatalyst is used, the Ni-Co-based main catalyst may be contained in an amount of 0.001 to 5 wt%. More preferably, it may be used in an amount of 0.1 to 4 wt%, 0.3 to 4 wt%, or 1 to 3 wt%. In addition, according to a preferred embodiment of the present invention, the Ni-Co-based main catalyst preferably contains Ni in excess of Co, for example, it is preferable to contain Ni:Co in a ratio of 1.01 to 5:1, preferably 2.5 to 3.5:1.

[0080] According to a preferred embodiment of the present invention, the cocatalyst may be at least one of Zr, Ti, Ce, and a noble metal component, and more preferably, two or more composite metals may be used.

[0081] According to a preferred embodiment of the present invention, the precious metal component is contained in an amount of 0.0001 to 1.5 wt% based on the total weight of the active component metal, but may be contained in a smaller amount than the main catalyst.

[0082] According to a preferred embodiment of the present invention, the noble metal component used in the cocatalyst may contain 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, and most preferably, one or more components selected from palladium and platinum may be used.

[0083] According to a preferred embodiment of the present invention, the noble metal component as a cocatalyst may be contained in an amount of 0.01 to 0.5 wt% based on the total weight of the active metal. More preferably, it may be contained in an amount of 0.01 to 0.3 wt%, even more preferably, 0.01 to 0.2 wt%, and most preferably, 0.01 to 0.1 wt%.

[0084] According to a preferred embodiment of the present invention, one or more metals selected from Zr, Ti, and Ce may be used as a cocatalyst, and this component may be contained in an amount of, for example, 0.1 to 1.0 wt% based on the total weight of the active metal. More preferably, one or more of Zr and Ti may be used. The content of such metal components may be contained in an amount of more preferably 0.1 to 0.8 wt%, and most preferably 0.1 to 0.5 wt%.

[0085] According to a preferred embodiment of the present invention, the catalyst may be used as a support having a specific surface area of ​​0.1 to 5 m2 / g. In addition, a support having a water absorption rate of 15 to 55% may be preferably used.

[0086] According to a preferred embodiment of the present invention, the catalyst may use one or more of cordierite, SiC, Al2O3, and SiO2 as a support. Typically, a support for a conventional dry reforming catalyst may be used, but an alumina-silica-based support is particularly preferably used.

[0087] According to a preferred embodiment of the present invention, an example of a method for manufacturing a catalyst for reforming reaction of the present invention includes the steps of preparing a porous support as a support, for example; preparing a nickel metal oxide precursor; preparing a cobalt metal oxide precursor; mixing the nickel metal oxide and the cobalt metal oxide so that the weight ratio of nickel:cobalt is (1.01-4):1 and supporting the support so that the amount is 0.3-4 wt%; and drying the support on which the nickel metal oxide and the cobalt metal oxide are supported and calcining it at a temperature of 500°C or higher.

[0088] In addition, as an example of a method for producing a combined gas using a catalyst for producing a synthesis gas according to the present invention, a method for producing a synthesis gas by a reforming reaction of a reducing gas using carbon dioxide is included, characterized in that in a method for reforming a reducing gas using carbon dioxide, methane and carbon dioxide are used as reaction gases, but carbon dioxide is used in excess, a catalyst for a reforming reaction is applied to the reaction system of the reaction gas, but the catalyst is a catalyst containing nickel and cobalt in excess of nickel compared to cobalt, and particularly preferably Ni-Co is used as a main catalyst, and at least one of Zr, Ti, Ce, and precious metal components is used as a cocatalyst, but the main catalyst is used in excess of the cocatalyst to carry out the reforming reaction.

[0089] According to a preferred embodiment of the present invention, the reaction of the reducing gas and carbon dioxide is preferably carried out under conditions in which carbon dioxide is in excess, for example, carbon dioxide / reducing gas can react at a weight ratio of 1.01 to 2. If the reaction condition is insufficient in carbon dioxide, the oxidizing agent is insufficient compared to the reducing agent, so other reactions such as methane decomposition reactions occur in addition to the reforming reaction, and there is a concern that the pressure inside the reactor may increase due to rapid carbon deposition resulting from the decomposition reaction of the reducing gas, making it difficult to proceed with the reaction or that the reaction may be terminated. In addition, under reaction conditions in which carbon dioxide is used in excessive amounts, unlike the insufficient conditions, there is difficulty in securing long-term stability and in deactivating the catalyst due to rapid oxidation of the catalytic metal active component by the excess oxidizing agent.

[0090] According to the present invention, the catalyst of the present invention, unlike existing catalysts, is a new catalyst for reforming reactions, particularly suitable for dry reforming or dry-wet composite reforming, and by using a cocatalyst of a specific component therein, the long-term stability of the catalyst can be excellently secured.

[0091] According to a preferred embodiment of the present invention, when added as a co-catalyst of a reforming catalyst used in the carbon dioxide excess reforming reaction of the present invention, it has the characteristic of being able to suppress the oxidation of the active metal by having excellent reduction characteristics under reaction conditions with a large oxidizing atmosphere, rather than the slightly reducing atmosphere reaction conditions of a general reforming reaction. Therefore, although the components that can be used as co-catalysts each have different characteristics, it is not easy to select a component that has excellent temperature durability even in high-temperature reactions, is heat-resistant, does not participate in carbon deposition during the reaction process, induces strong mutual bonding between the active metal and the support, protects the active metal from sintering phenomenon, and suppresses oxidation so that excellent catalytic activity can be stably maintained. Therefore, in this respect, it is preferable to consider the main catalyst component of the present invention and select a specific component as described above as a co-catalyst component that can stably maintain the catalytic activity.

[0092] In the present invention, due to the selective use of such a cocatalyst, it is expected that a synergistic effect can be achieved in which the catalytic activity of the Ni-Co catalyst, which is the main catalyst, is additionally significantly improved in the reforming reaction of a reducing gas using an excessive amount of carbon dioxide, thereby maintaining a high conversion rate and securing long-term catalyst stability in the reforming reaction.

[0093] Meanwhile, according to the present invention, by reforming a reducing gas using carbon dioxide, for example, by using an excess of carbon dioxide and using a catalyst for producing synthesis gas through the reforming reaction as described above, an excellent conversion rate can be achieved.

[0094] Therefore, the present invention includes a method for producing synthesis gas by reforming a carbon-based reducing gas, characterized in that, in reforming a reducing gas using an excess of carbon dioxide, Ni-Co having the above-described composition is used as a main catalyst, and at least one metal selected from Zr, Ti, and Ce and a precious metal component are used as a co-catalyst, and the main catalyst is used in an amount greater than the co-catalyst to carry out the reforming reaction.

[0095] According to the present invention, in the process of manufacturing synthesis gas by such reforming reaction, the catalyst of the present invention additionally uses a co-catalyst and controls a series of configurations such as the amount of reducing gas used compared to carbon dioxide, the amount of catalyst component used, and the application of a co-catalyst, thereby suppressing carbon deposition and imparting heat-resistant properties, thereby extending the use period of the catalyst from 2,000 hours to tens of thousands of hours, and greatly improving the catalytic activity while maintaining the catalytic stability, thereby obtaining an excellent conversion rate effect.

[0096] Hereinafter, the present invention as described above will be described in detail based on specific examples, but the present invention is not limited to the examples exemplified herein.

[0097]

[0098] [Example 1]

[0099] A commercial alumina-silica-based oxide was used as a support for a reforming catalyst without any further treatment. Before loading the active component, a small amount (less than 2 wt%) of a fixing agent (alumina sol) was attached to the support, and the support was heat-treated at 500°C for 4 hours to fix the adhesive to the support. The ratio of the active component, nickel-cobalt, was fixed at 3:1, and the content of the active component was 1.5 wt%, thereby preparing a catalyst. An active metal precursor solution containing 0.05 wt% of palladium nitrate in addition to the nickel-cobalt precursor in the form of nitrate was prepared using deionized water as a solvent, and the active component was loaded onto the catalyst using a wet impregnation method. The catalyst loaded with the active component was calcined at 500°C for 4 hours, thereby preparing the catalyst of Example 1.

[0100]

[0101] [Example 2]

[0102] Catalyst 2 was prepared in the same manner as Example 1, except that the palladium content was increased to 0.2 wt%.

[0103]

[0104] [Example 3]

[0105] Example catalyst 3 was prepared in the same manner as Example 1, except that the platinum content was added at 0.05 wt%.

[0106]

[0107] [Example 4]

[0108] A commercial alumina-silica-based oxide was used as a support for a reforming catalyst without any other heat treatment. The catalyst was prepared by fixing the ratio of nickel and cobalt as active components at 3:1 and setting the content of the active component to 1.5 wt%. A precursor solution containing 0.05 wt% palladium nitrate and 0.25 wt% zirconium oxychloride in addition to a nickel-cobalt precursor in the form of a nitrate was prepared using deionized water as a solvent, and the active component was loaded onto the catalyst using a wet impregnation method. The catalyst loaded with the active component was calcined at 500°C for 4 hours to prepare the catalyst of Example 4.

[0109]

[0110] [Example 5]

[0111] A catalyst of Example 5 was prepared in the same manner as in Example 4, except that the zirconium content was increased to 0.5 wt%.

[0112]

[0113] [Example 6]

[0114] A catalyst of Example 6 was prepared in the same manner as Example 4, except that the content of titanium was added to 0.25 wt%.

[0115]

[0116] [Comparative Example 1]

[0117] A catalytically active component was supported on a support without using a fixing agent. A binary catalyst was prepared using a wet impregnation method with the content of the active component, nickel-cobalt, fixed at 1.5 wt% and the nickel-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.

[0118]

[0119] [Comparative Example 2]

[0120] The content of the active ingredient was fixed at 1.5 wt%, and a precursor solution containing cobalt nitrate and palladium dissolved therein was prepared, and the active metal was supported using a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare a catalyst of Comparative Example 2.

[0121]

[0122] [Comparative Example 3]

[0123] The content of the active ingredient was fixed at 1.5 wt%, and a precursor solution containing cobalt nitrate and zirconium oxychloride was prepared, and the active metal was supported using a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare a catalyst of Comparative Example 3.

[0124]

[0125] [Comparative Example 4]

[0126] The content of the active ingredient was fixed at 1.5 wt%, a solution containing nickel nitrate and palladium was prepared, and the active metal was supported using a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours to prepare a catalyst of Comparative Example 4.

[0127]

[0128] [Comparative Example 5]

[0129] The content of the active ingredient was fixed at 1.5 wt%, and a solution containing nickel nitrate and zirconium oxychloride was prepared, and the active metal was supported using a wet impregnation method. The supported catalyst was calcined at 500°C for 4 hours, thereby preparing a catalyst of Comparative Example 5.

[0130]

[0131] [Experimental Example 1]

[0132] A catalyst for dry reforming reaction was manufactured by using a composite active ingredient of Ni and Co as a catalytic active ingredient on a porous support, but adjusting the mixing ratio of Ni and Co and adjusting the weight of the use to 2 wt% of the total active ingredient, and using carbon dioxide and methane gas, a continuous dry reforming reaction was performed under the same conditions as Example 1, and the conversion rate of the reaction gas (CO2, CH4) was measured at each reaction temperature.

[0133] The results are shown in comparison with Fig. 1 (Fig. 1A is CH4, Fig. 1B is CO2). Fig. 1 is a graph and related data showing the results of an experiment evaluating the conversion rate according to the Ni and Co content ratio of a Ni-Co catalyst applied as an example of a catalyst for a dry reforming reaction according to the present invention.

[0134] Looking at the results of this experiment, the initial performance is similar depending on the Ni-Co content ratio (see Figure 1), but in terms of reaction durability, the higher the Ni ratio, the better the durability (see Figures 2A and 2B).

[0135]

[0136] [Experimental Example 2]

[0137] A catalyst for dry reforming was manufactured by using a composite active ingredient of Ni and Co as a catalytic active ingredient on a porous support, but adjusting the mixing ratio of Ni and Co and adjusting the weight of the active ingredient to 2 wt% of the total active ingredient. A continuous dry reforming reaction was performed under the same conditions as Example 1 using carbon dioxide and methane gas, and the usable life of the catalyst was measured.

[0138] The results are shown in the above Fig. 2 (Fig. 2A, Fig. 2B). Fig. 2 is a graph showing the results of a catalyst life evaluation experiment for a case where the Ni and Co content ratio of a Ni-Co catalyst applied as an example of a catalyst for a dry reforming reaction according to the present invention is Ni:Co=3:1 (Fig. 2A) and a case where the Ni and Co content ratio is Ni:Co=1:1 (Fig. 2B).

[0139] According to these results, a catalyst life of approximately 6,000 hours or more was confirmed in the case of Ni:Co=3:1, while a catalyst life of approximately 1,700 hours was confirmed in the case of Ni:Co=1:1.

[0140] Therefore, in the above examples, it was confirmed that when Ni was contained in excess compared to Co, a significantly superior catalyst life was exhibited compared to when the same amount was used. However, even when the same amount was used, a much longer catalyst life could be exhibited compared to before. Therefore, since even when Ni and Co were used in substantially the same amount, a very excellent effect was exhibited, it was confirmed that even when Ni was excessive at a very small level, an excellent effect on the long-term catalyst life was also observed.

[0141]

[0142] [Experimental Example 3]

[0143] The catalysts for dry reforming of Examples 4 and 5 were prepared by adjusting the weight of the catalytically active component (active component: Co, Ni) to 0.5 to 3 wt% on a support (porous support) to which a small amount (within 2 wt%) of a fixing agent (alumina sol) was attached. The catalysts were continuously subjected to dry reforming at a reaction temperature of 900°C and a reaction gas ratio of methane:carbon dioxide of 1:1 using carbon dioxide and methane gas, and the service life, which is the usable time of the catalyst, was measured.

[0144] The results are as shown in Fig. 3.

[0145] According to the experimental results of Fig. 3, the durability life of the used catalyst was confirmed to be more than 1,000 hours under desirable conditions, which is an ultra-long lifespan that is 10 to 20 times longer than the maximum lifespan of existing catalysts.

[0146]

[0147] [Experimental Example 4]

[0148] In order to evaluate the performance of the catalysts manufactured according to Examples 1 to 6 and Comparative Examples 1 to 5, a reforming reaction of methane and carbon dioxide was performed using the following method, and the results are shown in Fig. 4.

[0149] The catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were subjected to reforming reaction evaluation in a fixed-bed reactor equipped with an external heating system, and the reactor was a tubular reactor made of quartz material with an outer diameter of 1 / 2 inch. Before 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 gas of methane:carbon dioxide was reduced at a reaction ratio of 1:1.7 for 1,000 h. -1 3,000 h -1 The catalytic reaction was performed by supplying the gas to the reactor at a space velocity of . At this time, the catalytic reaction was performed under atmospheric pressure and a reaction temperature of 800 to 1000 ℃, and the gas discharged after the reaction was analyzed using a gas chromatography system equipped with a thermal conductivity detector.

[0150] The reaction results according to the use of the catalyst manufactured in the above example and comparison under the above reaction conditions are shown in Table 1 below.

[0151] Methane conversion rate (%) Carbon dioxide conversion rate (%) H2 / CO ratio (%) Note (reaction time (h)) Example 175.766.40.49980 Example 274.9660.48890 Example 375.466.20.48980 Example 495.776.20.621,800 Example 595.1760.611,600 Example 695.576.20.621,800 Comparative example 110.55.751.1535 Comparative example 27.84.31.1320 Comparative example 33.52.150.9215 Comparative example 49.55.21.1530 Comparative example 55.73.40.9715

[0152] The conversion rates of methane and carbon dioxide of the catalysts according to Examples 1 and 4 and Comparative Example 1 performed under the above reaction conditions are shown in comparison in FIG. 4 (FIG. 4A, FIG. 4B).

[0153] As shown in Fig. 4, the catalyst of Example 4 showed the highest conversion of methane (Fig. 4A) and carbon dioxide (Fig. 4B), and exhibited stable catalytic activity during 1,800 hours of reforming reaction. The catalyst of Example 1 exhibited similar catalytic activity to the catalyst of Example 4 and exhibited stable reaction activity for 500 hours, but the activity of the catalyst 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 catalytic stability was observed compared to the catalyst of Example 1. The catalyst of Example 3 showed similar reaction activity and stability trends to Example 1.

[0154] In addition, the catalyst of Example 5 exhibited similar activity to the catalyst of Example 4, but the stability of the catalyst was observed to be lower than that of the catalyst of Example 4. The catalyst of Example 6 exhibited similar reaction activity and stability trends to those of Example 4.

[0155] Meanwhile, the catalyst of Comparative Example 1 exhibited similar activity to the catalysts of Examples 1 to 4, but a rapid decrease in the activity of the catalyst was observed after a reaction time of 35 hours.

[0156] From the results of reforming reaction experiments on the above Examples 1 to 6 and comparative example sample catalysts, it was confirmed that the activity and stability of the catalyst under the carbon dioxide-excess reducing gas reforming reaction conditions proposed in the present invention were greatly affected by the addition of precious metals and zirconium-based cocatalysts, and that excellent effects were exhibited at specific contents for the components used of the cocatalysts.

[0157] In the present experimental results, the results of performing a reforming reaction under the reaction conditions of Experimental Example 1 by adding precious metals and zirconium to the single metals of nickel and cobalt, which are the main active metals in the catalysts of Comparative Examples 2 to 5, were explored. The results are shown in Table 1 above.

[0158] As confirmed in Table 1 above, in the case of the catalysts of Comparative Examples 2 and 3, even when palladium or zirconium was added as a cocatalyst to the single metal cobalt, low activity and low stability were exhibited under reaction conditions with excess carbon dioxide.

[0159] In addition, from these experimental results, it can be interpreted that both the activity and stability of the catalyst are greatly reduced due to the oxidation of cobalt, the active ingredient, in the oxidation reaction atmosphere caused by excess carbon dioxide.

[0160] In addition, the catalysts proposed in Comparative Examples 4 and 5 exhibited higher catalytic activity and stability than the catalysts of Comparative Examples 2 and 3, but were observed to have significantly lower activity and stability than the multi-component composite oxide catalyst proposed in the present invention.

[0161] In the above experiments, it was confirmed that the catalysts of Comparative Examples 1 to 5 showed an increase in activity and stability by adding a noble metal cocatalyst or one or more additional cocatalysts of Zr, Ti, and Ce under reforming reaction conditions with a ratio of methane and carbon dioxide of 1:1.1 to 2.

[0162] However, under the carbon dioxide-excessive reducing gas reforming conditions proposed in the present invention, i.e., reforming conditions in which mild oxidation reactions predominate, it is not possible to ensure the activity and stability of the catalyst through oxidation of the active metals of nickel and cobalt. In particular, in the case of cobalt, a rapid decrease in reaction activity is observed due to relatively rapid metal oxidation compared to the active metal of nickel under reforming reaction conditions in which an oxidizing atmosphere predominates.

[0163]

[0164] From the above experiments, it was confirmed that the catalyst for producing synthesis gas through a reducing gas reforming reaction utilizing carbon dioxide according to the present invention exhibited excellent conversion rates and extended lifespans in a Ni-Co catalyst composition selected under specific conditions in experiments on dry reforming reactions for efficient removal of carbon dioxide. Furthermore, it was confirmed that the catalyst system exhibited excellent long-term stability compared to conventional reforming catalysts due to the use of a cocatalyst.

Claims

1. A catalyst for the reforming reaction of a reducing gas using carbon dioxide, characterized in that a mixed catalyst component including nickel and cobalt is supported on a catalyst support, nickel is contained in an excess amount compared to cobalt, and the catalyst life is 1,500 hours or more based on the total reaction time used in the dry reforming reaction.

2. A catalyst for producing synthesis gas by reforming a reducing gas using carbon dioxide, characterized in that, in claim 1, a mixed catalyst component containing nickel and cobalt is dispersed and contained on the surface of a support at 0.3 to 4 wt% of the total catalyst composition.

3. A catalyst for producing synthesis gas by reforming a reducing gas using carbon dioxide, characterized in that, in claim 1, nickel and cobalt are contained in a weight ratio of (1.01 to 4):

1.

4. A catalyst for producing synthesis gas, characterized in that the reforming reaction of the reducing gas in claim 1 is a reaction between methane and carbon dioxide in which carbon dioxide is used in excess.

5. A catalyst for producing synthesis gas, characterized in that the reforming reaction of the reducing gas in claim 1 is a dry reforming reaction or a composite reforming reaction including a dry reforming reaction.

6. A catalyst for producing synthesis gas by reforming a reducing gas using carbon dioxide, characterized in that it further comprises at least one of Zr, Ti, Ce, and precious metal components as a cocatalyst in any one of claims 1 to 5.

7. A catalyst for producing synthesis gas, characterized in that the co-catalyst content in claim 6 is 0.001 to 1.5 wt% and is contained in a smaller amount than the main catalyst.

8. A catalyst for producing synthesis gas, characterized in that the precious metal component used in the cocatalyst according to claim 6 is at least one component selected from among Pd, Pt, Rh, Ru, Os, and Ir.

9. A catalyst for producing synthesis gas, characterized in that in claim 6, the cocatalyst contains 0.01 to 1.0 wt% of at least one metal selected from Zr, Ti, and Ce, and at least one precious metal selected from Pd, Pt, Rh, Ru, Os, and Ir.

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