KR20230112976A - Catalyst for synthetic natural gas synthesis, method for preparing the same, and method for synthesizing synthetic natural gas with carbon dioxide - Google Patents

Abstract

Catalyst for synthetic natural gas synthesis comprising a composite metal oxide structure formed of a composite metal oxide composed of cobalt and aluminum and having a porous mesopore pore structure, and a metal cocatalyst supported in the pores of the composite metal oxide structure, and a method for preparing the same And a method for synthesizing synthetic natural gas from carbon dioxide using the same is provided.

Description

Catalyst for synthesizing synthetic natural gas, method for preparing the same, and method for synthesizing synthetic natural gas using carbon dioxide

A catalyst for synthesizing synthetic natural gas (SNG) using carbon dioxide, a method for preparing the same, and a method for synthesizing synthetic natural gas in which methane and hydrocarbons are mixed using the catalyst are provided.

As a countermeasure against global warming due to the increase in carbon dioxide emissions, various studies on the utilization and storage of carbon dioxide are being actively conducted. The methanation reaction is one of the methods for utilizing carbon dioxide, and methane is synthesized by reacting carbon dioxide and hydrogen. In addition, the carbon dioxide methanation reaction is also emerging as a method of effectively using surplus hydrogen generated in a power-to-gas (P2G) energy storage technology or a biogas reforming process, which has recently emerged.

The active materials used in the carbon dioxide methanation reaction are known noble metals and nickel. In general, nickel catalysts have high conversion and methane selectivity, but have been reported to have a risk of carbon deposition (Catalysts. 2017, 7, 59). In particular, nickel catalysts are known as suitable catalysts for methanation reactions because they are inexpensive compared to noble metal catalysts and show high catalytic activity at a certain level.

Meanwhile, in order to meet the ever-increasing demand for natural gas fuel, research on producing synthetic natural gas is also being conducted. As shown in Table 1 below, the methane component of synthetic natural gas synthesized by a general methanation reaction exceeds about 98% and has a calorific value lower than that of LNG or LPG by about 1000 kcal/m ³ . Therefore, in order to increase the overall calorific value of the product, there is a need to synthesize heavier hydrocarbons such as butane and propane.

division composition Calorific value (kcal/m ³ ) LNG Methane (85% or more), Ethane (2%) Others (Propane, _N2, etc.) 9,700 ~ 10,800 png Methane (90% or more), other (CO ₂ , N ₂ ) 9,000 ~ 10,200 SNG Methane (98% or more), other (H ₂ , CO ₂ , N ₂ ) 9,000 ~ 9,500

Cobalt-based catalysts, which show excellent activity in the Fische-Tropsch synthesis reaction of syngas composed of carbon monoxide and hydrogen, show methanation reaction activity when the reaction gas is changed to carbon dioxide instead of carbon monoxide (Catalysis Today 2016, 277, 161). At this time, since the activity of the Fischer-Tropsch synthesis reaction remains slightly, it is possible to produce synthetic natural gas with a high calorific value, including the above-mentioned heavy hydrocarbons.

In addition, the cobalt catalyst is advantageous in terms of operating cost of the reactor because it is operated at a temperature of 200 to 300 ° C., which is relatively lower than the operating conditions of a general methanation catalyst such as nickel or iron or a Fischer-Tropsch catalyst.

It is known that the activity of cobalt catalysts is mainly influenced by the number of active sites exposed on the surface. Therefore, in order to obtain high catalytic activity, a process of uniformly dispersing cobalt as an active material on a support having a very large specific surface area is essential. Since mesoporous materials with mesopores were developed as the most suitable material for realizing such high dispersion or wide catalyst specific surface area, they have been widely used in the field of catalysts (Appl. Catal. B., 2009, 89). , 365-374; Catal. Today, 2012, 185, 168-174).

It has been reported that meso-Co ₃ O ₄ ) catalysts using meso-Co 3 O 4 have been used in various organic reactions and battery-related technologies, but there are few reports of using mesoporous cobalt alone in catalytic reactions involving pretreatment processes such as reduction. . This is mainly due to the collapse of the mesostructure that occurs during the pretreatment process of the catalyst, especially under a reducing atmosphere. A mesoporous cobalt-aluminum catalyst in which about 25% of aluminum is mixed is known to have excellent stability against such structural collapse (Chem Commun., 2016, 52, 4820-4823).

The mesoporous cobalt-aluminum catalyst has a high mass transfer rate compared to a catalyst prepared by dispersing an active material in the form of small nanoparticles on the surface of a support having a very large surface area. In addition, the mesoporous cobalt-aluminum catalyst has a large number of active sites exposed on the surface, and shows excellent activity in the synthesis reaction of synthetic natural gas from carbon dioxide. However, the reaction rate of the catalyst is not fast enough and the unconverted reactants are significant, which forces the introduction of separation and recycling processes. Therefore, it is required to improve the reaction activity through the introduction of an appropriate enhancer.

Korean Patent Publication 2018-0114301 Korean registered patent 1578540

P. Frontera, A. Macario, M. Ferraro, P. Antonucci, Supported Catalysts for CO2 Methanation: A Review, Catalysts, 7(2) (2017) 59. C.G. Visconti, M. Martinelli, L. Falbo, L. Fratalocchi, L. Lietti, CO2 hydrogenation to hydrocarbons over Co and Fe-based Fischer-Tropsch catalysts, Catalysis Today, 277 (2016) 161-170. T. Tsoncheva, L. Ivanova, J. Rosenholm, M. Linden, Cobalt oxide species supported on SBA-15, KIT-5 and KIT-6 mesoporous silicas for ethyl acetate total oxidation, Applied Catalysis B: Environmental, 89 (2009) 365-374. J. -S. Jung, S.W. Kim, D.J. Moon, Fischer-Tropsch Synthesis over cobalt based catalyst supported on different mesoporous silica, Catalysis Today, 185 (2012) 168-174. C. -I. Ahn, Y.J. Lee, S.H. Um, J.W. Bae, Ordered mesoporous CoMOx (M = Al or Zr) mixed oxides for Fischer-Tropsch synthesis, Chemical Communications, 52 (2016) 4820-4823.

One embodiment of the present invention is to provide a catalyst for synthetic natural gas synthesis reaction in which the mesostructure is effectively maintained and deactivation is suppressed, and a method for preparing the same.

One embodiment of the present invention is to provide a method for producing synthetic natural gas with a high calorific value through simultaneous progress of a methanation reaction of carbon dioxide and a Fischer-Tropsch synthesis reaction using a catalyst.

In addition to the above tasks, embodiments according to the present invention may be used to achieve other tasks not specifically mentioned.

According to one embodiment, synthetic natural gas has a regular mesoporous main framework in which cobalt oxide and aluminum oxide are uniformly mixed, and transition metals such as zirconium, cerium, and zinc are added. Cobalt-aluminum hybrid catalyst for use, method for producing it using a hard template method, and methanation reaction and Fischer-Tropsch synthesis reaction occur simultaneously using the same to produce high exothermic synthetic natural gas including methane and hydrocarbons A method is provided.

A catalyst for synthetic natural gas synthesis reaction according to an embodiment is formed of a composite metal oxide composed of cobalt and aluminum, includes a composite metal oxide structure having a mesoporous structure, and transition metals such as zirconium, cerium, and zinc are added. .

Aluminum according to an embodiment may be contained in an amount of 10 mol% to 50 mol% compared to cobalt.

The catalyst according to an embodiment may have a specific surface area of 40 m 2 /g to 120 m 2 /g, and an average pore diameter of 4 nm to 12 nm.

A method for preparing a catalyst for synthetic natural gas synthesis according to an embodiment includes: (1) injecting a precursor solution in which a cobalt oxide precursor and an aluminum oxide precursor are dissolved into pores of a mesoporous silica mold, and then firing the precursor solution; (2) Forming a composite metal oxide structure composed of oxides of cobalt and aluminum and having a mesoporous structure by removing the mesoporous silica template obtained in step (1) using an acidic or basic solution, and (3) the above step ( A third step of impregnating the composite metal oxide structure obtained in 2) into a solution in which the promoter metal precursor material is dissolved and then heat-treating the composite metal oxide structure to support phosphorus in the pores of the composite metal oxide structure.

In one embodiment, the step of preparing the mesoporous silica template before the first step is further included, and the step of preparing the mesoporous silica template comprises adding a copolymer and tetraethoxysilane (TEOS, Tetraethoxysilane) as a structure directing agent to a solvent. It may include dissolving to form a silica precipitation solution, hydrothermal treatment of the silica precipitation solution, and removing the copolymer from the reactants after the hydrothermal synthesis with a mixed solution containing an acidic solution. .

In one embodiment, the promoter metal precursor is an acetate or nitrate of zirconium (Zr), cerium (Ce), manganese (Mn), zinc (Zn), iron (Fe), or nickel (Ni) metal. and chloride and the like.

In one embodiment, the promoter metal in the third step may be supported in an amount of 2% to 10% by weight based on the weight of the composite metal oxide structure.

In the method for synthesizing synthetic natural gas according to an embodiment, in the methanation reaction and the Fischer-Tropsch synthesis reaction of hydrogenating carbon dioxide to produce hydrocarbons such as methane, (1) disposing a catalyst for synthesizing natural gas inside the reactor (2) activating the catalyst by reducing at least some of the cobalt oxides of the catalyst to cobalt by supplying a reducing gas into the reactor, and (3) supplying a syngas containing hydrogen and carbon dioxide into the reactor to reduce the methane It includes the step of synthesizing hydrocarbons such as

In one embodiment, the step of performing the synthetic natural gas synthesis reaction may be performed at a reaction temperature of about 200 °C to about 350 °C and a reaction pressure of about 15 bar to about 25 bar.

According to an embodiment, a new catalyst is prepared by adding an enhancer for enhancing the activity of the carbon dioxide methanation reaction and the Fischer-Tropsch reaction to a meso-cobalt alumina catalyst having mesopores, through which high calorific value synthetic natural gas is produced from carbon dioxide A highly active catalyst for synthesis can be provided.

1 is a diagram showing the CO ₂ conversion rate of a catalyst.

With reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are used for the same or similar components throughout the specification. In addition, in the case of widely known known technologies, detailed descriptions thereof will be omitted.

Throughout the specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

Throughout the specification, the methanation reaction or Fischer-Tropsch synthesis reaction refers to a process of producing hydrocarbons such as methane by reacting carbon dioxide and hydrogen.

A catalyst for synthesis of synthetic natural gas according to an embodiment includes a composite metal oxide structure formed of an oxide of a composite metal composed of cobalt and aluminum, having a mesoporous structure, and to which a transition metal such as zirconium, cerium, or zinc is added.

The catalyst for synthetic natural gas synthesis may be a catalyst used in methanation reaction or Fischer-Tropsch synthesis. For example, the catalyst may be a catalyst used in Low Temperature Fischer-Tropsch Synthesis (LTFT). The low-temperature Fischer-Tropsch synthesis is a Fischer-Tropsch synthesis performed at a low temperature, and the reaction may be performed at about 200 °C to about 250 °C and about 15 bar to about 25 bar.

The composite metal oxide structure may have a porous structure including mesopores. The composite metal oxide structure may be prepared using mesoporous silica as a template. The mesoporous silica template may be a porous material having mesopores having a pore size of about 2 nm to about 50 nm.

The mesoporous silica template may be directly synthesized or a commercially available product may be purchased and used, and is not particularly limited. For example, one or more mesoporous silicas may be used in KIT-6, SBA-15, MCM-41, MCM-48, HMS, AMS-10, FDU-12, and the like.

The metal cocatalyst supported in the pores of the composite metal oxide structure may be supported as an activity enhancer for the synthetic natural gas synthesis reaction.

In one embodiment, the metal cocatalyst may contain about 2% to 10% by weight based on the weight of the composite metal oxide. If the content of the metal cocatalyst is less than 2% by weight, the activity of the synthetic natural gas synthesis reaction may not be sufficiently promoted, and if it exceeds 10% by weight, the metal cocatalyst is adsorbed on the active site on the catalyst surface, thereby reducing the reactivity of the catalyst. can rather hinder it. For example, a catalyst for synthesizing synthetic natural gas may contain about 4 wt% to 6 wt% of zirconium based on the weight of the composite metal oxide.

In one embodiment, the catalyst may have a specific surface area of about 60 m 2 /g to about 120 m 2 /g, and an average pore diameter of about 4 nm to about 6 nm. Furthermore, the catalyst may have a specific surface area of about 80 m ² /g to about 100 m ² /g, and an average pore size of about 4 nm to 5 nm.

According to the catalyst for synthetic natural gas synthesis according to an embodiment, a small amount of a metal cocatalyst is supported inside the pores of a composite metal oxide structure formed of oxides of a composite metal composed of cobalt and aluminum and having a porous mesoporous structure, It is possible to enhance the activity of the synthetic natural gas synthesis reaction without adversely affecting the skeleton of the pore structure.

A method for preparing a catalyst for synthesis of synthetic natural gas is a first step of injecting a precursor solution in which a cobalt oxide precursor and an aluminum oxide precursor are dissolved into pores of a mesoporous silica mold and then calcining the mesoporous silica using an acidic or basic solution. A second step of removing the mold to form a composite metal oxide structure formed of an oxide of a composite metal including cobalt and aluminum and having a porous mesopore structure, and a solution in which the metal precursor material of the cocatalyst is dissolved. and a third step of supporting a cocatalyst in the pores of the composite metal oxide structure by heat treatment after impregnation.

In the first step, the cobalt oxide precursor and the aluminum oxide precursor may be injected into the pores of the mesoporous silica template using a precursor solution in which the cobalt oxide precursor and the aluminum oxide precursor are dissolved.

The cobalt oxide precursor is not particularly limited, and includes cobalt-containing nitrate salt, cobalt-containing chloride salt, cobalt-containing bromide salt, cobalt-containing acetate salt and/or acetylacetonate ( acetylacetonate) salt and the like can be used. For example, cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O), cobalt chloride (CoCl ₂ 6H ₂ O), and cobalt acetate (Co(CH ₃ COO) ₂ 4H ₂ O) may be used.

The aluminum oxide precursor is not particularly limited, and includes aluminum-containing nitrate salt, aluminum-containing chloride salt, aluminum-containing bromide salt, aluminum-containing acetate salt and/or hydroxide ( hydroxide) salt and the like can be used. For example, aluminum nitrate (Al(NO ₃ ) ₃ 9H ₂ O) may be used.

The first step may be performed by mixing a mesoporous silica template with a precursor solution containing a composite metal oxide precursor composed of cobalt and aluminum to form a gel, drying the gel, and then firing it.

In order to fill the pores of the mesoporous silica template well with the composite metal oxide precursor made of cobalt and aluminum, a process of removing moisture contained in the pores may be performed first. For example, moisture contained in the pores of the mesoporous silica mold may be removed by drying the mesoporous silica mold in an oven at about 100° C. or higher for about 1 hour or more.

When the mesoporous silica template is mixed with the precursor solution, the composite metal oxide precursor solution made of cobalt and aluminum may penetrate into the pores of the mesoporous silica template through capillary action.

Subsequently, the mesoporous silica template injected with the precursor solution may be slowly dried at a temperature lower than the boiling point of the solvent of the precursor solution. For example, when water is used as a solvent for the precursor solution, the drying temperature may be about 80° C., and drying may be performed for about 12 hours. When the mesoporous silica mold into which the precursor solution is injected is dried at a temperature lower than the boiling point of the solvent, the solvent evaporates slowly, so that the cobalt oxide precursor material and the aluminum oxide precursor material penetrating into the pores of the silica mold do not come out of the pores and inside the pores. can stay in

Subsequently, the dried mesoporous silica mold may be fired at a high temperature to change the cobalt oxide precursor and the aluminum oxide precursor into oxides of a composite metal including cobalt and aluminum. For example, for firing the dried mesoporous silica mold, the temperature may be raised to about 550 °C at a heating rate of about 1 °C/min, and then maintained at about 550 °C for about 3 hours.

In the second step, the mesoporous silica template may be removed using an acidic or basic solution. As the acidic or basic solution, a strong base solution or a strong acid solution may be used. For example, mesoporous silica templates can be removed using an aqueous NaOH solution or an aqueous HF solution. For example, mesoporous silica templates can be removed using an aqueous solution of NaOH at a concentration of about 2 M.

In the third step, the metal cocatalyst may be supported in the pores of the composite metal oxide structure by impregnating the complex metal oxide structure into a solution in which the precursor material of the metal cocatalyst is dissolved, and then drying and firing the same.

The solution in which the precursor material of the metal cocatalyst is dissolved may be an aqueous solution using water as a solvent. In this case, the precursor of the metal cocatalyst may include a water-soluble precursor material such as a nitrate salt, a chloride salt, a bromide salt, and an acetate salt. For example, zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ 6H ₂ O) or cerium nitrate hexahydrate (Ce(NO ₃ ) ₃ 6H ₂ O) may be used as a precursor of the metal cocatalyst.

During the drying step, the solvent of the solution in which the precursor material of the cocatalyst is dissolved may be removed. For example, the drying step may be performed at about 70 °C to about 110 °C for about 6 hours to about 24 hours.

During the sintering step, the precursor material of the metal cocatalyst is decomposed and the metal cocatalyst may be supported on the surface and inside the pores of the composite metal oxide structure. For example, in the sintering step, the temperature of the composite metal oxide structure in which the precursor material of the metal cocatalyst is attached to the inside and surface of the pores is heated to about 500 ° C. at a heating rate of about 1 ° C./min, and then the temperature of about 500 ° C. It can be carried out by holding for 3 hours.

The metal cocatalyst may be supported in an amount of about 2% to 10% by weight based on the weight of the composite metal oxide structure. The metal cocatalyst used as an activity enhancer may be prepared by supporting a small amount in order to prevent an effect of inhibiting the reactivity of the catalyst by being adsorbed on the active site on the surface of the catalyst. For example, when prepared by supporting in an amount of about 2 to 5% by weight, the reactivity of the catalyst can be further enhanced.

In the synthetic natural gas synthesis method for producing hydrocarbons such as methane by hydrogenating carbon dioxide according to an embodiment, disposing a catalyst for synthetic natural gas synthesis in a reactor, supplying a reducing gas to the inside of the reactor to obtain cobalt oxide of the catalyst It includes activating a catalyst by reducing at least a part of it to cobalt, and synthesizing hydrocarbons such as methane by supplying a syngas containing hydrogen and carbon dioxide into a reactor.

The reactor may be a fixed bed reactor as a synthetic natural gas synthesis reactor, but is not limited thereto.

The reducing gas may include hydrogen and nitrogen gas. For example, the reducing gas may include about 4% to about 12% of hydrogen gas and residual nitrogen gas.

The process of reducing a portion of the cobalt oxide of the catalyst to cobalt with a reducing gas may be performed for about 6 hours to 24 hours, for example, about 12 hours.

The reduction process may be performed at a temperature of about 300 °C to about 500 °C, for example, the catalyst may be activated by being performed at 400 °C.

In the step of synthesizing liquid hydrocarbons, a synthetic natural gas synthesis reaction may be performed by supplying syngas into the reactor. Syngas may include hydrogen, nitrogen and carbon dioxide. For example, in syngas, hydrogen may account for a volume fraction of about 65% to about 80%, and carbon dioxide may account for a volume fraction of about 15% to about 30%.

For example, in the step of performing the synthetic natural gas synthesis reaction, the reaction temperature may be about 200 °C to about 350 °C, and the reaction pressure may be about 10 bar to about 30 bar. At this time, the space velocity may be about 4000 L/kg cat./h to about 32,000 L/kg cat./h.

The synthetic natural gas synthesis reaction may be a methanation reaction or a Fischer-Tropsch synthesis reaction. In the Fischer-Tropsch synthesis reaction, the reaction temperature may be about 200 °C to 250 °C, and the reaction pressure may be about 15 bar to 35 bar. For example, the reaction pressure may be about 20 bar.

Hereinafter, embodiments of the present invention will be described in detail. However, the following examples are merely some embodiments of the present invention, and the present invention should not be construed as being limited to the following examples.

Preparation Example 1: Complex Metal Oxide Structure (Conventional Complex Metal Oxide Structure Catalyst)

About 10.0 g of KIT-6, a mesoporous silica template material, is dried in an oven at about 110° C. for about 1 hour. About 16.8 g of cobalt nitrate hexahydrate and about 5.4 g of aluminum nitrate nonahydrate used as a precursor were put into about 10.0 g of distilled water and completely dissolved. The precursor solution in which the cobalt oxide precursor and the aluminum oxide precursor are dissolved is poured into KIT-6 dried for about 1 hour at once, and then sufficiently mixed. The bright red KIT-6 powder in which the precursor solution was well mixed was slowly dried in an oven at about 80 °C for about 12 hours, and distilled water as a solvent was evaporated. The dried composite metal oxide is heated to about 550 °C at a heating rate of about 1 °C/min, and then a firing process is performed for about 3 hours. In order to remove KIT-6 from the composite metal oxide formed by firing, the fired composite metal oxide was added to about 2 M NaOH aqueous solution and slowly stirred for about 30 minutes. After the stirring is completed, the base solution is separated by centrifuging the composite metal oxide at about 7000 rpm for about 7 minutes. The composite metal oxide is washed a second time with about 200 ml of about 1 M NaOH aqueous solution, and then washed three times with distilled water and once with ethanol, a total of four times. After washing, drying at about 80 ° C. for about 4 hours to finally prepare a composite metal oxide structure, and the prepared catalyst is marked as meso-CoAlO _x . The specific surface area of the catalyst is about 100 m ² /g.

Example 1: Ce(5)/meso-CoAlO _x catalyst

A catalyst was prepared by loading about 5% of cerium, a metal cocatalyst, based on the weight of the composite metal oxide structure as a promoter on the composite metal oxide structure prepared in Preparation Example 1.

About 0.15 g of cerium nitrate hexahydrate (about 99%), a cerium precursor, is dissolved in about 0.5 g of distilled water. The cerium precursor solution is supported on the prepared composite metal oxide structure of about 1 g by wet impregnation. The catalyst powder mixed with the cerium precursor is slowly dried in an oven at about 80° C. for about 12 hours to evaporate distilled water as a solvent. The dry composite metal oxide structure is calcined at about 500° C. for about 3 hours to prepare a cerium-supported catalyst for synthesizing synthetic natural gas. The prepared catalyst is expressed as Ce(5)/meso-CoAlO _x , and the specific surface area of the prepared catalyst is about 70.7 m ² /g.

A synthetic natural gas synthesis reaction is performed with the prepared catalyst, and prior to the reaction, H ₂ (about 5%)/N ₂ reducing gas is flowed at about 30 cm ³ /min for about 12 hours, and the catalyst is reduced for about 12 hours do. Syngas (gas containing H ₂ and CO ₂ ) After about 0.1 g of catalyst was put in a fixed bed reactor at a pressure of about 20 bar, a space velocity of about 8000 L/kg cat./h, and a temperature of about 230 °C. The reaction is performed while flowing syngas at a flow rate of about 13.3 ml/min. The reaction is carried out for about 60 hours as a continuous reaction. During the reaction, repeated analyzes of CO ₂ conversion and hydrocarbon selectivity for the reaction product were performed at intervals of about 1 hour using gas chromatography. CO ₂ conversion during the reaction shows a stable activity of about 48.8% for 60 hours. The composition of the synthesized natural gas was 92.4% CH ₄ and 6.4% C ₂ -C ₄ , and the high calorific value was 10,652 kcal/m ³ .

Example 2: Zn(5)/meso-CoAlO _x catalyst

A catalyst was prepared by supporting zinc, a metal cocatalyst, as an enhancer on the composite metal oxide structure prepared in Preparation Example 1 in an amount of about 5% based on the weight of the composite metal oxide structure.

About 0.13 g of zinc nitrate hexahydrate (about 98%), a zinc precursor, is dissolved in about 0.5 g of distilled water. About 1 g of the prepared composite metal oxide structure is dried in an oven at about 110° C. for about 1 hour to remove moisture. The zinc precursor solution is supported on the dried composite metal oxide structure by wet impregnation. The zinc-supported composite metal oxide structure is slowly dried in an oven at about 80° C. for about 12 hours to evaporate distilled water as a solvent. The dried composite metal oxide structure is calcined at about 500° C. for about 3 hours to prepare a zinc-supported catalyst for synthesizing synthetic natural gas. The prepared catalyst is expressed as Zn(5)/meso-CoAlO _x , and the specific surface area of the prepared catalyst is about 91.4 m ² /g.

A synthetic natural gas synthesis reaction is performed with the prepared catalyst, and prior to carrying out the reaction, the catalyst is reduced for about 12 hours under H ₂ (about 5%)/N ₂ reducing gas at a flow rate of about 30 cm ³ /min. Syngas (gas containing H ₂ and CO ₂ ) After about 0.1 g of catalyst was put in a fixed bed reactor at a pressure of about 20 bar, a space velocity of about 8000 L/kg cat./h, and a temperature of about 230 °C. The reaction is performed while flowing syngas at a flow rate of about 13.3 ml/min. The reaction is carried out for about 60 hours as a continuous reaction. During the reaction, repeated analyzes of CO ₂ conversion and hydrocarbon selectivity for the reaction product were performed at intervals of about 1 hour using gas chromatography. During the reaction time of about 60 hours carried out, the CO ₂ conversion rate shows a stable activity of about 38.2%. The composition of the synthesized synthetic natural gas was 92.2% CH ₄ and 6.8% C ₂ -C ₄ , and the high calorific value was 10,675 kcal/m ³ .

Comparative Example 1: Synthetic natural gas synthesis method using a conventional composite metal oxide structure

A synthetic natural gas synthesis reaction was performed using the conventional composite metal oxide structure prepared in Preparation Example 1, and prior to the reaction, H ₂ (about 5%)/N ₂ reducing gas was supplied to about 30 cm ³ / for about 12 hours. min and reduce the catalyst for about 12 hours. Syngas (gas containing H ₂ and CO ₂ ) After about 0.1 g of catalyst was put in a fixed bed reactor at a pressure of about 20 bar, a space velocity of about 8000 L/kg cat./h, and a temperature of about 230 °C. The reaction is performed while flowing syngas at a flow rate of about 13.3 ml/min. The reaction is carried out for about 60 hours as a continuous reaction. During the reaction, repeated analyzes of CO ₂ conversion and hydrocarbon selectivity for the reaction product were performed at intervals of about 1 hour using gas chromatography. CO ₂ conversion during the reaction shows a stable activity of about 38.7% for 60 hours. The composition of synthesized synthetic natural gas is 95.5% CH ₄ and 3.5% C ₂ -C ₄ , and the high calorific value is 10,048 kcal/m ³ .

Comparative Example 2: Zr(5)/meso-CoAlO _x catalyst

A catalyst was prepared by loading about 5% of zirconium, a metal cocatalyst, based on the weight of the composite metal oxide structure as a promoter on the composite metal oxide structure prepared in Preparation Example 1.

About 0.16 g of zirconium oxynitrate hydrate (about 99%), a precursor of zirconium, is dissolved in about 0.5 g of distilled water. The zirconium precursor solution is supported on the prepared composite metal oxide structure of about 1 g by wet impregnation. The catalyst powder mixed with the cerium precursor is slowly dried in an oven at about 80° C. for about 12 hours to evaporate distilled water as a solvent. The dry composite metal oxide structure is calcined at about 500° C. for about 3 hours to prepare a zirconium-supported catalyst for synthesizing synthetic natural gas. The prepared catalyst is expressed as Zr(5)/meso-CoAlO _x , and the specific surface area of the prepared catalyst is about 82.3 m ² /g.

A synthetic natural gas synthesis reaction is performed with the prepared catalyst, and prior to the reaction, H ₂ (about 5%)/N ₂ reducing gas is flowed at about 30 cm ³ /min for about 12 hours, and the catalyst is reduced for about 12 hours do. Syngas (gas containing H ₂ and CO ₂ ) After about 0.1 g of catalyst was put in a fixed bed reactor at a pressure of about 20 bar, a space velocity of about 8000 L/kg cat./h, and a temperature of about 230 °C. The reaction is performed while flowing syngas at a flow rate of about 13.3 ml/min. The reaction is carried out for about 60 hours as a continuous reaction. During the reaction, repeated analyzes of CO ₂ conversion and hydrocarbon selectivity for the reaction product were performed at intervals of about 1 hour using gas chromatography. CO ₂ conversion during the reaction shows a stable activity of about 48.2% for 60 hours. The composition of the synthesized synthetic natural gas was 94.3% CH ₄ and 4.6% C ₂ -C ₄ , and the high calorific value was 10,312 kcal/m ³ .

Comparative Example 3: Ni(5)/meso-CoAlO _x catalyst

A catalyst was prepared by loading about 0.5% of nickel, a metal cocatalyst, based on the weight of the composite metal oxide structure as a promoter on the composite metal oxide structure prepared in Preparation Example 1.

About 0.27 g of nickel nitrate hexahydrate (about 98%), a nickel precursor, is dissolved in about 0.5 g of distilled water. A nickel precursor solution is supported on the prepared composite metal oxide structure of about 1 g by a wet impregnation method. The nickel-supported composite metal oxide structure is slowly dried in an oven at about 80° C. for about 12 hours to evaporate distilled water as a solvent. The dried composite metal oxide structure is calcined at about 500° C. for about 3 hours to prepare a nickel-supported catalyst for Fischer-Tropsch synthesis. The prepared catalyst is expressed as Ni(5)/meso-CoAlO _x , and the specific surface area of the prepared catalyst is about 58.7 m ² /g.

A synthetic natural gas synthesis reaction was performed with the prepared catalyst, and prior to carrying out the reaction, the catalyst was reduced for about 12 hours under H ₂ (about 5%)/N ₂ reducing gas at a flow rate of about 30 cm ³ /min. Syngas (gas containing H ₂ and CO ₂ ) After about 0.1 g of catalyst was put in a fixed bed reactor at a pressure of about 20 bar, a space velocity of about 8000 L/kg cat./h, and a temperature of about 230 °C. The reaction is performed while flowing syngas at a flow rate of about 13.3 ml/min. The reaction is carried out for about 60 hours as a continuous reaction. During the reaction, repeated analyzes of CO ₂ conversion and hydrocarbon selectivity for the reaction product were performed at intervals of about 1 hour using gas chromatography. During the reaction time of about 60 hours carried out, the CO ₂ conversion rate shows a stable activity of about 44.3%. The composition of the synthesized synthetic natural gas is 98.2% CH ₄ and 1.8% C ₂ -C ₄ , and the high calorific value is 9,745 kcal/m ³ .

The experimental results are shown in Table 2 and FIG. 1 below.

division catalyst CO ₂ conversion rate (carbon mole %) CO selectivity
(carbon mole %) hydrocarbon distribution
C ₁ /C _2-4 /C ₅₊
(carbon mole%) of synthetic natural gas
total calorific value
(kcal/m ³ ) Catalyst specific surface area
(m ² /g) best After 60 hours reaction Example 1 Ce(5)/meso-CoAlO _x 44.3 42.8 0.4 92.4/6.4/1.2 10,652 70.8 Example 2 Zn(5)/meso-CoAlO _x 40.5 38.2 0.0 92.2/6.8/1.0 10,675 91.4 Comparative Example 1 meso-CoAlO _x 42.0 38.7 1.7 95.5/3.5/1.0 10,048 100.5 Comparative Example 2 Zr(5)/meso-CoAlO _x 49.8 48.2 0.8 94.3/4.6/1.1 10,312 82.3 Comparative Example 3 Ni(5)/meso-CoAlO _x 46.7 44.3 0.7 97.6/2.0/0.3 9,745 58.7 The reaction was carried out using syngas with a volume fraction of H ₂ /N ₂ /CO ₂ = 72/4/24 Reaction conditions were T=230'C, P=20 bar, and space velocity was 8,000 L/kg cat./h lim
The reaction proceeded for about 60 hours, and the average value of the catalyst activity for the last 10 hours was recorded.

As shown in Table 1, when the synthetic natural gas synthesis reaction is performed using the catalyst for synthetic natural gas synthesis in which about 5% by weight of cerium or zinc is supported as a metal cocatalyst, the catalyst activity is stably improved and relatively high C Due to the ₂₊ hydrocarbon selectivity, it is possible to provide synthetic natural gas with a higher calorific value. The calorific value of the synthetic natural gas synthesized through the examples is about 10,650 kcal/m ³ , which is higher than the calorific value of about 9,500 kcal/m ³ of general synthetic natural gas (SNG) and the average calorific value of liquefied natural gas (LNG) of 10,000 kcal. /m higher than ³ . In the case of Comparative Example 1 in which the metal cocatalyst was not supported, or Comparative Examples 2 and 3 in which Zr or Ni was selected, it could be confirmed that relatively low activity or excessively high methane selectivity was exhibited. Therefore, compared to the catalyst prepared without using an enhancer (Comparative Example 1), when prepared by carrying cerium or zinc, which is a metal cocatalyst, as an enhancer, more carbon dioxide can be synthesized into synthetic natural gas with higher energy. .

1 shows the CO ₂ conversion rate of the catalyst. Specifically, FIG. 1 shows the CO ₂ conversion rate TOS (Time On Stream) when a synthetic natural gas synthesis reaction is performed for about 60 hours using the prepared catalyst. It can be seen from FIG. 1 that, in the case of a catalyst in which an appropriate amount of cerium or zinc is used as a promoter, stable and high activity is maintained during a reaction time of about 60 hours.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

Claims (16)

cobalt oxide and aluminum oxide are uniformly mixed, and
A cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis reaction having a regular mesoporous mainframework.
In paragraph 1,
A cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis reaction, wherein the molar ratio of aluminum constituting the mesoporous main skeleton is between 0.1 and 0.5 relative to cobalt.
In paragraph 1,
The cobalt-aluminum hybrid catalyst has a specific surface area of 40 m 2 / g to 120 m 2 / g and an average pore diameter of 4 nm to 12 nm.
In paragraph 1,
The cobalt-aluminum hybrid catalyst includes a cocatalyst containing at least one of zirconium (Zr), cerium (Ce), manganese (Mn), iron (Fe), nickel (Ni), or zinc (Zn), synthetic natural Cobalt-aluminum hybrid catalyst for gas synthesis.
In paragraph 4,
The cocatalyst is a method for producing a cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis, which is supported by 2% to 10% by weight based on the weight of the cobalt-aluminum hybrid catalyst.
A first step of injecting a precursor solution in which a cobalt oxide precursor and an aluminum oxide precursor are dissolved into the pores of a mesoporous silica mold and then firing it;
A second step of removing the mesoporous silica template using an acidic or basic solution to form a composite metal oxide structure formed of oxides of cobalt and aluminum and having a porous mesoporous structure; and
A third step of impregnating the composite metal oxide structure in a solution in which a metal precursor material is dissolved and then carrying out heat treatment to support a cocatalyst in the pores of the composite metal oxide structure.
Method for producing a cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis comprising a.
In paragraph 6,
The cocatalyst includes at least one of zirconium (Zr), cerium (Ce), manganese (Mn), iron (Fe), nickel (Ni), or zinc (Zn), a cobalt-aluminum hybrid catalyst for synthesis of natural gas. Manufacturing method of.
In paragraph 7,
The cocatalyst is a method for producing a cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis, which is supported by 2% to 10% by weight based on the weight of the composite metal oxide structure.
In paragraph 6,
A method for producing a cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis having a specific surface area of 40 m 2 / g to 120 m 2 / g and an average pore diameter of 4 nm to 12 nm after the cocatalyst is supported.
Disposing a cobalt-aluminum hybrid catalyst for syngas synthesis reaction in which cobalt oxide and aluminum oxide are uniformly mixed and having a regular mesoporous mainframework inside the reactor;
activating the cobalt-aluminum hybrid catalyst by supplying a reducing gas into the reactor to reduce at least some of the cobalt oxides of the cobalt-aluminum hybrid catalyst to cobalt; and
supplying syngas containing hydrogen and carbon dioxide into the reactor to synthesize hydrocarbons containing methane.
Comprising, synthetic natural gas synthesis method from carbon dioxide.
In paragraph 10,
from carbon dioxide, wherein the cobalt-aluminum hybrid catalyst comprises a cocatalyst comprising one or more of zirconium (Zr), cerium (Ce), manganese (Mn), iron (Fe), nickel (Ni), or zinc (Zn). Synthesis of synthetic natural gas synthesis method.
In paragraph 11,
The cocatalyst is a synthetic natural gas synthesis method from carbon dioxide that is supported 2% to 10% by weight based on the weight of the cobalt-aluminum hybrid catalyst.
In paragraph 10,
The step of performing the synthetic natural gas synthesis reaction is carried out at a reaction temperature of 200 ℃ to 350 ℃, a reaction pressure of 15 bar to 25 bar, synthetic natural gas synthesis method from carbon dioxide.
Injecting a precursor solution in which a cobalt oxide precursor and an aluminum oxide precursor are dissolved into the pores of a mesoporous silica mold, followed by firing;
Removing the mesoporous silica template using an acidic or basic solution to form a composite metal oxide structure formed of oxides of cobalt and aluminum and having a porous mesoporous structure;
Preparing a cobalt-aluminum hybrid catalyst by impregnating the composite metal oxide structure in a solution in which a metal precursor material is dissolved and then performing heat treatment to support a cocatalyst in the pores of the composite metal oxide structure
Disposing the cobalt-aluminum hybrid catalyst inside the reactor;
activating the cobalt-aluminum hybrid catalyst by supplying a reducing gas into the reactor to reduce at least some of the cobalt oxides of the cobalt-aluminum hybrid catalyst to cobalt; and
supplying syngas containing hydrogen and carbon dioxide into the reactor to synthesize hydrocarbons containing methane.
Comprising, synthetic natural gas synthesis method from carbon dioxide.
In paragraph 14,
The cocatalyst includes at least one of zirconium (Zr), cerium (Ce), manganese (Mn), iron (Fe), nickel (Ni), or zinc (Zn), a cobalt-aluminum hybrid catalyst for synthesis of natural gas. Manufacturing method of.
In paragraph 15,
The cocatalyst is a method for producing a cobalt-aluminum hybrid catalyst for synthetic natural gas synthesis, which is supported by 2% to 10% by weight based on the weight of the composite metal oxide structure.

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