KR101969554B1 - Fe-Co based complex catalyst for producing Synthetic-Natural-Gas of higher heating level and Use thereof - Google Patents

Abstract

The present invention relates to a process for producing iron and cobalt in the presence of Co and Fe containing catalysts containing iron and cobalt in an amount of 61 to 99 parts by weight and 1 to 39 parts by weight, respectively, based on 100 parts by weight of iron and cobalt, Synthesis of methane and C2-C4 paraffin-containing synthetic natural gas from carbon monoxide. The catalyst according to the present invention is a catalyst which uses two or more active metals so that the FT synthesis reaction and the methanation reaction coexist simultaneously. The catalyst is composed of hydrogen and carbon monoxide mainly composed of methane and has a high C2-C4 paraffin content of 11,000 Kcal / Nm ³ ~ 13,000 Kcal / Nm ³ , and is a catalyst that can simplify the process compared to existing natural gas synthesis processes due to high C1-C4 productivity.

Description

(Fe-Co based complex catalyst for producing Synthetic-Natural-Gas of higher heating level and Use thereof)

The present invention relates to iron-cobalt complex catalysts for producing high calorific value synthetic natural gas, and to a process and a method for producing the same. The catalyst according to the present invention is capable of producing high-calorific synthetic natural gas having a high content of methane and C2-C4 paraffin from hydrogen and carbon monoxide, and enables a process simplification due to high C1-C4 productivity.

Natural gas is a major component of CH ₄ , and it is a clean fuel that generates less SO _{2 and} less NOx, dust, and CO ₂ than coal or oil during combustion, and its demand is continuously increasing worldwide. However, it is anticipated that the supply of natural gas will not follow the increase in demand. Therefore, it is expected that gasification of carbon-containing materials such as coal, biomass, and waste will produce syngas which is a mixture of H ₂ and CO, (SNG: synthetic natural gas) by methane conversion has been attracting new interest worldwide.

Coal is more than 200 years old and has the longest current fossil fuel, relatively low price per calorie, distributed in various regions around the world, and is advantageous in terms of supply and energy security.

Coal gasification technology converts most of the energy of coal into chemical energy, which reduces the efficiency of the entire process due to the temperature change in the downstream purification process. The main products of the coal gasification reaction are carbon monoxide and hydrogen, and these gases give a large calorific value when burned. That is, the gasification reaction converts a considerable amount of energy in the sample into a gas containing chemical energy such as carbon monoxide or hydrogen. Even if these gases are rapidly cooled, their chemical energy is maintained. If necessary, they are combusted and then passed through a gas turbine or a steam turbine It has the advantage that energy can be re-established.

Coal prices have been on a downward trend due to rising oil prices due to indiscriminate consumption of petroleum resources and the recent decline in demand for coal due to the development of shale gas. In addition, according to the development plan of coal chemical industry in China, energy and chemical production technology using coal, which is relatively long and cheap in price, is attracting attention. Among them, synthetic natural gas production technology started from the development of coal methane production process due to the surge of natural gas demand in the United States in the 1960s.

Coal gasification technology is a process of producing synthesis gas (Syngas) composed mainly of CO and H ₂ by incompletely burning coal by injecting coal into a gasifier and then producing a mixture of sulfur compounds such as COS and H ₂ S (SNG), Coal to Liquid (CTL), chemical products (methanol, DME, etc.) and power using synthetic / power generation processes.

The coal gasification system consists of a gasifier, an air separation unit as an oxygen supply unit, and a gas purification unit.

The IGCC, the most widely known coal gasification technology, is an eco-friendly next generation power generation system in which a low-grade fuel is subjected to incomplete combustion and gasification under the conditions of high temperature and high pressure to produce syngas and then subjected to a purification process to drive gas turbines and steam turbines Technology.

Synthetic natural gas (SNG) may be natural gas obtained from coal. As shown in Fig. 9, there are a method for obtaining SNG from coal, a method for obtaining synthesis gas obtained through coal gasification through methane synthesis reaction, a method for obtaining SNG by reacting coal directly with hydrogen (Hydrogasification) There is a method of obtaining SNG by reacting coal with steam at low temperature (catalytic gasification).

From the gasification of coal to the present, the synthetic natural gas production process consists of the gasification process of coal and the methanation process of syngas produced by coal gasification. Although the gasification process of coal itself is complicated, the syngas methanation process to date is composed of two or three methanation reactors, or the methanation process and the C2-C4 paraffin production process are linked, and the process configuration is complicated There are difficulties in securing the operation of the process and securing facilities.

The catalyst technology, which is the core technology of the synthetic natural gas production process, was mainly developed by nickel catalysts such as Haldor-Topsoe, BASF, Johson & Metthey and Sud-Chemie.

The Ni-based catalyst produces 1 mole of methane and 1 mole of water from 2 moles of carbon monoxide, and the product composition is mostly composed of methane. As a result, the calorific value of the synthetic natural gas produced from the Ni-based catalyst is about 8500 Kcal / Nm ^{3, which} is much lower than that of LNG (about 10,500 Kcal / Nm ³ ) and LPG (about 12,000 Kcal / Nm ³ ) The process is complicated by linking the C2-C4 paraffin production process. Therefore, efforts have been made to develop a catalyst capable of simultaneous production of methane and C2-C4 paraffin, and to simplify the process thereof.

An object of the present invention is to provide a catalyst capable of producing high-heat-generating synthetic natural gas (SNG) having a high content of methane and C2-C4 paraffin from hydrogen and carbon monoxide and capable of simplifying processes owing to high C1-C4 productivity and a method for producing the same I want to.

In a first aspect of the present invention, there is provided a method for producing a synthetic natural gas having a high calorific value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ , wherein the iron and cobalt, Cobalt ferrite (CoFe ₂ O ₄ ), and 61 to 99 parts by weight and 1 to 39 parts by weight of cobalt, respectively, in the presence of Co and Fe containing catalyst, Containing synthetic natural gas. ≪ RTI ID = 0.0 > A < / RTI >

The second aspect of the present invention is a catalyst for the production of synthetic natural gas having a high heating value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ , wherein iron and cobalt 61 to 99 parts by weight and 1 to 39 parts by weight, respectively, of Fe and Co, which are characterized by containing a cobalt ferrite of spinel structure , A catalyst for simultaneous FT synthesis and methanation.

A third aspect of the present invention is a method for producing Fe and Co containing catalysts for producing synthetic natural gas having a high heating value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ , wherein 100 parts by weight of iron and cobalt A first step of preparing a precursor solution by mixing an Fe precursor and a Co precursor so that iron and cobalt are 61 to 99 parts by weight and 1 to 39 parts by weight, respectively; A second step of preparing a mixed solution of a precipitant and distilled water; A third step of mixing the solution obtained in the first step with the solution obtained in the second step; A fourth step of precipitating and filtering the mixed solution obtained in the third step; And the filtrate obtained in the fourth step is dried and fired at 300 to 700 ° C to obtain a cobalt ferrite having a specific surface area of 70 to 120 m ² / g and an average particle size of pores of 7 to 30 and a fifth step of preparing a catalyst having a specific surface area of 200-300 nm.

Hereinafter, the present invention will be described in detail.

Through experiments, the inventors first confirmed the following results according to the catalyst composition:

(i) The Fe monometallic catalyst has a high heating value but is not suitable as a SNG synthesis catalyst because it has low CO conversion, high CO to CO ₂ conversion, and low SNG yield.

(ii) CO conversion by CO addition was close to 100% in all composition ratios and CO to CO ₂ conversion was decreased.

(iii) Cobalt ferrite predominates over cobalt oxide when the Co ratio is less than 39 wt% of the total active metal, thereby reducing CH ₄ selectivity, increasing C2-C4 selectivity, and increasing C5 + selectivity Respectively. Also, The paraffin selectivity reached 100% by Co addition.

(iv) The yield of SNG was increased due to the decrease of CO to CO ₂ conversion depending on the addition and amount of Co. However, when the Co ratio exceeds 39 wt% of the total active metal, the formation of Co ₃ O ₄ dominates the methanation reaction. The selectivity of CH ₄ was increased and the selectivity of C ₂ -C ₄ was decreased. For example, when the Co ratio is 20 wt% of the total active metal, the calorific value is about 12,000 Kcal / Nm ^3, but when the Co ratio is 50 wt%, the calorific value is greatly reduced to about 10,000 Kcal / Nm ³ . There was no significant difference in the 70:30 area. That is, when the proportion of Co in the active metal is 39 wt% or less, the amount of heat generated is increased due to low CH ₄ selectivity and high C ₂ -C ₄ selectivity. This is due to the formation of cobalt ferrite, which is a suitable result for synthesis of high calorie SNG.

The present invention is based on this finding, the methane present invention according to the Fischer-Tropsh synthesis reaction and the methanation reaction is controlling the Co ratio of the active metal on the Fe and Co-containing catalysts occurs at the same time to less than 39wt% and Co ₃ O ₄ screen The reaction superiority is inhibited and a high calorific value synthetic natural gas having a composition ratio of C ₂ -C ₄ selectivity is produced.

The Fe- and Co-containing catalysts according to the present invention are characterized in that, based on 100 parts by weight of iron and cobalt as active metals, 61 to 99 parts by weight and 1 to 39 Cobalt is not a main catalyst, but iron is a main catalyst, and it can produce synthetic natural gas having a high heating value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ .

The active metal in the catalyst may be iron oxide, cobalt oxide, iron, cobalt, iron-cobalt oxide and iron-cobalt alloy or mixtures thereof. Further, the catalyst may include a spinel structure of cobalt ferrite in an oxidized state, and may be composed of iron oxide, cobalt oxide, iron, cobalt, iron-cobalt and iron-cobalt oxide in a reduced state. Is Fe ₂ O ₃ , Fe ₃ O ₄ , or both, The cobalt oxide may be CoO, Co ₃ O ₄ , or both.

The Co and Fe containing catalyst according to the present invention is a catalyst which uses two or more kinds of active metals so that the FT synthesis reaction and the methanation reaction coexist simultaneously and is a catalyst composed mainly of hydrogen and carbon monoxide and methane and having a high content of C2- It is possible to produce synthetic natural gas with a calorific value and can simplify the process compared to the existing natural gas synthesis process due to high C1-C4 productivity.

<Fischer-Tropsch synthesis reaction>

_{nCO + 2nH 2 → - (CH} 2) n- + nH 2 O

<Methanation reaction>

_{nCO + 3nH 2 ↔ nCH 4 +} nH 2 O

The Co and Fe-containing catalyst according to the present invention may have a specific surface area of 70 to 120 m ² / g and an average particle size of pores of 7 to 30 nm.

Fischer-Tropsh Synthesis of Fe and Co containing both Fe and Co at the same time can increase the C2 to C4 composition ratio in the SNG through the Fischer-Tropsh synthesis reaction in the synthesis of SNG and the Fischer-Tropsh synthesis reaction through the methanation reaction. Unreacted CO and CO ₂ can be methanized to increase SNG yield. Due to these effects, it is possible to synthesize SNG with high yield in high yield by the above-mentioned method in which Fischer-Tropsh synthesis reaction and methanation reaction occur at the same time.

Synthetic natural gas produced by the catalyst according to the present invention may have a composition which exhibits a high calorific value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ . In one embodiment, the synthetic natural gas may be methane: C2-C4 paraffins (molar ratio) = 1: 0.5-1.

According to the present invention, a method for producing Fe and Co containing catalysts for producing synthetic natural gas having a high heating value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ ,

A first step of preparing a precursor solution by mixing an Fe-based precursor and a Co-based precursor so that iron and cobalt are 61 to 99 parts by weight and 1 to 39 parts by weight, respectively, based on 100 parts by weight of iron and cobalt;

A second step of preparing a mixed solution of a precipitant and distilled water;

A third step of mixing the solution obtained in the first step with the solution obtained in the second step;

A fourth step of precipitating and filtering the mixed solution obtained in the third step; And

The filtrate obtained in the fourth step is dried and calcined at 300 to 700 ° C to obtain a cobalt ferrite having a specific surface area of 70 to 120 m ² / g and an average particle size of pores of 7 to 30 nm And a fifth step of preparing a catalyst that is a catalyst for forming a catalyst.

Non-limiting examples of Fe-based precursors include iron nitrate, iron chloride, iron sulfate, iron acetate and mixtures thereof. Non-limiting examples of the Co-based precursor include cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate, .

The catalyst according to the present invention may further contain a cocatalyst capable of easily controlling the catalyst performance. Examples of the cocatalyst component include Pt, Pd, Rh, Ru, Mn, Cu, Zn, Mg, and combinations thereof. In the case of Pt, Pd, Rh, Ru and Cu co-catalysts, methane and paraffin selectivity can be increased. In the case of Mn, stability of the active metal is enhanced. In the case of Cu, Catalyst stability, and high hydrocarbon selectivity for SNG synthesis.

The co-catalyst component preferably maintains 0.5 to 5 parts by weight based on 100 parts by weight of the Fe and Co metals used. When the weight of the cocatalyst is less than the lower limit, the effect of promoting the cocatalyst is insufficient, which is undesirable. If the weight of the cocatalyst is more than the upper limit, undesired side reactions may occur due to the cocatalyst.

The catalyst according to the present invention may further comprise an inactive structural promoter component, and may be a metal oxide such as, but not limited to, alumina or silica. Structural enhancers can be used for the active metal dispersion in the Fe oxide structure. Thus, structure enhancing agents can be added to the catalyst by coprecipitation using an aluminum precursor (e.g., aluminum nitrate (Al (NO ₃ ) ₃ .9H ₂ O) without using an alumina support with other cobalt / iron precursors have. Further, when an aluminum precursor is used, since the ratio of the active metal in the overall composition of the catalyst can be maximized, it is possible to produce a catalyst having a high reaction activity.

The precursor of the cocatalyst and / or the precursor of the structure enhancer may further be included in the precursor solution of the first step.

Non-limiting examples of precursors of the cocatalyst and / or of the structure enhancer include nitrates, chlorides, sulfur oxides, super oxides, and mixtures thereof.

The second step is a step of preparing a mixed solution of a precipitant and distilled water. In order to coprecipitate the active metal and / or cocatalyst precursor and / or the structure enhancer precursor, the precipitant mixture solution is preferably an aqueous solution of a basic compound.

Non-limiting examples of precipitating agents include aqueous ammonia, sodium hydroxide, potassium hydroxide, magnesium hydroxide, ammonium carbonate, sodium carbonate, potassium carbonate, and mixtures thereof.

The precipitant is preferably used in an amount of 0.9 to 1.1 equivalents based on 1 equivalent of the active metal and the promoter and the structural enhancer component. If the amount of the basic compound used is less than 0.9 equivalent, the precipitation of the catalyst component is not complete. If the amount of the basic compound exceeds 1.1 equivalent, the precipitated catalyst component may be re-dissolved or the pH of the solution may be excessively increased. In addition, the pH of the basic compound aqueous solution is preferably maintained in a range of 6 to 9.

The third step is to mix the catalyst precursor solution and the precipitant solution. The mixed solution obtained in the third step may be in a slurry state.

The third step may be heating and stirring at the time of mixing. The slurry is heated and stirred for a predetermined time, and the heating temperature and heating time are preferably 60 to 100 ° C and 1 to 5 hours.

If the heating temperature and the heating time are less than the lower limit, it is difficult to uniformly disperse the active component and the promoter. If the heating temperature and the heating time are above the upper limit, the catalyst particle size increases and the active point decreases. So it is not desirable.

The fourth step is the precipitation filtration process. In the precipitation filtration, the slurry is washed with deionized water, and the amount of deionized water used is preferably washed three to five times using 30 to 50 ml per 1 g of the slurry mass.

If the amount of the deionized water and the number of times of washing are less than the lower limit, the removal of the impurities due to the precursor and the precipitant is insufficient, which is undesirable and when the upper limit is exceeded, there is no significant difference from the upper limit.

The water content of the filtrate obtained through the fourth step is preferably 50 to 80 wt%.

When the moisture content is less than the lower limit, it takes a considerable time to perform slurry filtration, which is not preferable because it takes a considerable time. When the upper limit is exceeded, pores are formed due to rapid evaporation of moisture in the slurry during drying, can do.

The fifth step is the drying and calcination of the filtrate. The filtrate is preferably dried for 3 to 5 hours per 1 g of the slurry at a temperature of 90 to 110 캜, and the product obtained after drying is preferably calcined at 450 to 650 캜 for 4 to 6 hours.

If the drying temperature is lower than the lower limit, it takes a considerable time to dry the slurry, which is not efficient. When the drying temperature exceeds the upper limit, voids are formed due to rapid evaporation of moisture in the slurry, .

When the drying time is lower than the above-mentioned range, the drying condition of the slurry is insufficient, which is undesirable. When the drying time is over the upper limit, the drying time is not significantly different from the upper limit and is inefficient.

If the firing temperature is less than the lower limit, the solvent and the organic impurities used in the production process are difficult to be completely removed by firing, the uniform dispersion of the active ingredient and the promoter is lowered, the catalyst strength is weak, The specific surface area and the active site of the catalyst component due to sintering of the catalytically active component may be reduced to lower the catalytic activity, so that the above range is preferably maintained.

The final product obtained through the above processes preferably has a specific surface area of 70 to 120 m ² / g and an average particle size of pores of 7 to 30 nm.

When the specific surface area is less than the lower limit, dispersion of the active metal and the promoter is insufficient, which is undesirable. When the specific surface area exceeds the upper limit, the dispersibility of the active metal and the enhancer is increased.

When the pore size is less than the lower limit or exceeds the upper limit, the methanation reaction is insufficient and the liquid hydrocarbon generation rate is increased, thereby lowering the SNG yield.

The final product is preferably composed of 61 to 99 parts by weight and 1 to 39 parts by weight of iron and cobalt based on 100 parts by weight of iron and cobalt, which are active metals.

When the composition of iron is below the lower limit, the methanation reaction by Co ₃ O ₄ predominates, the C2-C4 hydrocarbon selectivity of the product is lowered and the calorific value is lowered, and when the upper limit is exceeded, the Fe characteristic is dominant The SNG yield due to the water gas shift reaction is lowered and the olefin selectivity is high.

If the composition of the cobalt is below the lower limit, the formation of cobalt ferrite is insufficient and SNG yield is lowered. If the upper limit is exceeded, the methanation reaction due to the formation of Co ₃ O ₄ predominates and the C2- And the amount of heat generated is low.

In addition, the present invention provides a method for producing a synthetic natural gas having a composition capable of exhibiting a high heating amount of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ ,

Based on 100 parts by weight of iron and cobalt as active metals, 61 to 99 parts by weight and 1 to 39 parts by weight of iron and cobalt, respectively, in the presence of Co and Fe-containing catalysts containing cobalt ferrite of spinel structure, And a step of producing a C2-C4 paraffin-containing synthetic natural gas.

At this time, it may further include reducing the catalyst in a hydrogen atmosphere at a temperature ranging from 250 to 600 DEG C before or after the step a.

By subjecting the synthesis gas to the FT synthesis reaction and the methanation reaction simultaneously with the Fe- and Co-containing catalysts according to the present invention, the C1-C4 high heat amount synthetic natural gas can be produced.

Thus, in step a The selectivity of methane is 40-80 carbon mole%, the selectivity of C2-C4 hydrocarbon is 20-60 carbon mole%, and the proportion of paraffin among C2-C4 hydrocarbon is 90-100 carbon mole%.

The carbon monoxide-containing feed gas in step a may be a syngas produced by gasifying coal, biomass, or carbon-containing waste, or purified gas therefrom.

The H ₂ / CO ratio of the feed gas in step a is preferably 1.5 to 3.5.

When the H ₂ / CO ratio is lower than the lower limit, the SNG yield is lowered due to the water gas conversion reaction and the carbon deposition is increased. When the upper limit is exceeded, the selectivity of the C 2 -C 4 hydrocarbon is low, It is not preferable.

The synthetic natural gas synthesis reaction conditions are not particularly limited as they are generally used.

The catalyst of the present invention can be used in the reaction after reducing in a hydrogen atmosphere at a temperature ranging from 250 to 600 ° C in a fixed bed, a fluidized bed, and a slurry reactor.

In the step a, the reaction temperature is preferably 250 to 400 ° C, the reaction pressure is 20 to 40 bar, and the space velocity is 1000 ml / g _cat.h to 10000 ml / g _cath .

Conversion rates in the reaction conditions of 350 ° C, 30 atm and 6000 ml / g _cat.h space speed on the catalyst prepared by the process of the present invention show a range of 90-100 carbon mole%.

The composition of the synthetic natural gas produced is 40 to 80 carbon mole% of methane and 20 to 60 carbon mole% of C2-C4 hydrocarbon. The ratio of paraffins in the C2-C4 hydrocarbons is in the range of 90 to 100 carbon mole%, and by-products C5 or higher hydrocarbons, specifically C5-C12 gasoline oil fractions, range from 1 to 15 carbon mole%.

The present invention relates to a catalyst prepared by using two or more metals, which is produced by simultaneously using FT synthesis reaction and methanation reaction, to produce a high-calorific synthetic natural gas composed mainly of methane and having a high content of C2- A catalyst capable of being simplified can be produced.

Figure 1 shows the conversion and hydrocarbon selectivity of the catalysts prepared in the Examples and Comparative Examples.
FIG. 2 shows the amounts of heat generated and yields of SNG by the catalysts prepared in Examples and Comparative Examples.
Figure 3 shows the conversion and hydrocarbon selectivity of the catalysts prepared in the Examples and Comparative Examples.
FIG. 4 shows the amounts of heat generated and yields of SNG by the catalysts prepared in Examples and Comparative Examples.
Fig. 5 shows X-ray diffraction (XRD) results of the catalysts prepared in Examples and Comparative Examples before and after hydrogen reduction.
FIG. 6 shows X-ray diffraction (XRD) results of the catalyst prepared in Example and Comparative Example 5. FIG.
7 shows the results of the temperature-reduction characteristics (TPR) of the catalysts prepared in Examples and Comparative Examples.
8 shows the results of analysis of BET pore characteristics of the catalysts prepared in Examples and Comparative Examples.
9 is a conceptual diagram of a method for obtaining SNG from coal.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are intended to clearly illustrate the technical features of the present invention and do not limit the scope of protection of the present invention.

<Examples 1 to 4 and Comparative Examples 1 to 5> Production of Fe-Co heterogeneous metal catalyst for synthesizing high-calorie natural gas according to Fe: Co ratio

The catalyst compositions were iron nitrate (Fe (NO ₃ ) ₃ .9H ₂ O) as shown in Table 1 (amount of metal precursor used in the Fe-Co catalyst according to composition) so that the Fe: Co ratio was 100: 0 to 0: ), Cobalt nitrate (Co (NO ₃ ) ₂ .6H ₂ O) and aluminum nitrate (Al (NO ₃ ) ₃ .9H ₂ O) were dissolved in 200 ml of distilled water to prepare a precursor solution.

division Catalyst composition Precursor usage (g) Fe (NO ₃ ) ₃ .9H ₂ O Co (NO ₃ ) ₂ .6H ₂ O Al (NO ₃ ) ₃ .9H ₂ O Example 1 95Fe-5Co-20Al 50 1.82 20.34 Example 2 90Fe-10Co-20Al 50 3.85 21.47 Example 3 80Fe-20Co-20Al 50 8.67 24.15 Example 4 70Fe-30Co-20Al 50 14.86 27.60 Comparative Example 1 100Fe-20Al 50 0 19.32 Comparative Example 2 60Fe-40Co-20Al 50 23.11 32.30 Comparative Example 3 50Fe-50Co-20Al 50 34.66 38.64 Comparative Example 4 100Co-20Al 0 50 27.87 Comparative Example 5 Cobalt ferrite (ALDRICH, 99% purity) Comparative Example 6 Comparative Example 1 and Comparative Example 4 were mixed in a ratio of 8: 2 by physical mixing

The precipitant solution was prepared by dissolving 99.5% potassium carbonate (K ₂ CO ₃ ) in 300 ml of distilled water as shown in Table 2 (the amount of the precipitant used in the Fe-Co catalyst according to the composition).

division Catalyst composition K ₂ CO ₃ consumption (g) Example 1 95Fe-5Co-20Al 37.95 Example 2 90Fe-10Co-20Al 39.55 Example 3 80Fe-20Co-20Al 43.34 Example 4 70Fe-30Co-20Al 48.21 Comparative Example 1 100Fe-20Al 36.52 Comparative Example 2 60Fe-40Co-20Al 54.70 Comparative Example 3 50Fe-50Co-20Al 63.79 Comparative Example 4 100Co-20Al 39.34 Comparative Example 5 Cobalt ferrite (ALDRICH, 99% purity)

The precursor solution was added to precipitant solution under vigorous stirring to prepare a precipitate slurry. After stirring at 80 ° C for 3 hours, the resulting precipitate was filtered and washed several times with 1,000 ml of distilled water. The iron hydroxide cake produced by the above process was filtered and dried until the water content became 55 wt%. The dried iron hydroxide cake was dried in a drying oven at 110 DEG C for 12 hours and then calcined at 550 DEG C for 5 hours in an air atmosphere in a firing furnace.

The results of the atomic emission spectrometry (ICP-AES) of the catalyst prepared in Table 3 (the result of ICP analysis of the Fe-Co catalyst according to the composition) are shown.

Total metal ratio (wt%) Active metal ratio (wt%) Fe Co Al Fe Co Example 2 46.7 4.48 13.1 90.0 10.0 Example 3 44.3 11.0 13.6 80.0 20.0 Example 4 35.8 14.3 12.9 70.0 30.0 Comparative Example 1 93.1 0 6.9 100.0 0.0 Comparative Example 3 25.4 24.6 12.8 50.0 50.0

As shown in Table 3, the prepared catalysts were in conformity with the designed catalyst composition, and from the result, it was confirmed that the prepared catalysts could be prepared in accordance with the catalyst composition designed according to the catalyst active metal ratio Respectively.

0.5 g of the catalyst prepared in Examples and Comparative Examples was charged into a 1/2-inch stainless steel fixed bed reactor and subjected to reduction treatment under an atmosphere of H ₂ at 350 ° C. for 6 hours, The synthesis gas, which is a reactant, was injected into the reactor at a H ₂ / CO ratio of 3 at a reaction pressure of 30 bar and a space velocity of 6,000 ml / g _cat · h.

FIG. 1 shows the conversion and hydrocarbon selectivity according to Examples and Comparative Examples.

CO conversion was close to 100% in all composition ratios and CO to CO ₂ conversion was decreased by addition of Co active metal. In the case of the Fe single catalyst, CO to CO ₂ conversion was very high.

When the Co ratio is 39% or less of the total active metal, iron oxide (Fe₂O₃) And cobalt ferrite (CoFe₂O₄), Which causes CH₄Selectivity decreased, C2-C4 selectivity increased, and C5 + selectivity decreased. Also, The paraffin selectivity reached 100% by Co addition.

Cobalt ferrite was predominantly formed up to about 39 wt% of the total active metal to Co equivalent ratio of Fe to Co (2: 1) forming cobalt ferrite (CoFe ₂ O ₄ ). However, Exceeding 39 wt% of the metal forms cobalt oxide (Co ₃ O ₄ ), which causes a sharp decrease in the calorific value due to an increase in methane selectivity and a decrease in C ₂ -C ₄ selectivity.

A decrease in the C ₅₊ selectivity of the hydrocarbon selectivity may lead to an improvement in the SNG yield but an increase in the CH ₄ selectivity and a decrease in the C ₂ -C ₄ selectivity lead to a decrease in the amount of heat generated by the SNG, A composition ratio (Co ratio of the active metal of 39 wt% or less) having a high degree of C ₂ -C ₄ selectivity is optimally judged.

FIG. 2 shows the amounts of heat generated and yields of SNG according to Examples and Comparative Examples.

Compared with the Fe single metal catalyst, the heating value decreased from 12,800 Kcal / Nm ³ to 12,000 Kcal / Nm ³ , and there was no significant difference in Fe: Co from 95: 5 to 70:30. The yield of SNG increased with the amount of Co added and the amount of Co added. However, when the Co ratio was more than 40wt% of the total active metal, the amount of heat generation was much lower than that of high SNG yield. Low.

Therefore, in the case of the Fe single metal catalyst, the conversion of CO to CO ₂ is high and the yield of SNG is low. Therefore, when the proportion of Co in active metal is 40% or more, high CH ₄ selectivity and low C Due to the choice of _{2 to 4} , the amount of heat generated is lowered, so that it is not suitable for the synthesis of a high heat amount SNG.

<Experimental Example 1> Production of high-caloric synthetic natural gas by Fe-Co catalyst due to Cobalt ferrite and iron oxide

20Co-20Al), Example 4 (70Fe-30Co-20Al), and Comparative Example 3 (50Fe-50Co-20Al) (XRD), the temperature-reduction characteristics analysis (TPR) and the BET pore characterization results of the iron-cobalt heterometallic catalyst prepared in Comparative Example 4 (100Co-20Al) The results of ICP analysis of the Fe-Co catalyst according to the composition are shown in Figs. 5, 6, 7, and 8.

SSA ^a (m ² / g) Pore volume (cm ³ / g) Pore size (nm) Comparative Example 1 93.98 0.21 9.11 Example 2 117.84 0.22 7.46 Example 3 109.11 0.27 10.03 Example 4 105.89 0.31 12.05 Comparative Example 3 103.09 0.48 18.77 Comparative Example 4 70.20 0.52 30.02   a: Specific surface area

As a result of the XRD analysis of FIG. 5, Fe ₂ O ₃ peak was observed in the case of the catalyst made of iron alone in the catalyst calcined at 550 ° C., and Co ₃ O ₄ peak was observed in the catalyst made only of cobalt. Iron oxide and cobalt ferrite peaks were also observed in the case of the catalyst having Fe: Co ratios of 90:10, 80:20 and 70:30.

Fe metal, Co metal, and Fe-Co alloy peaks were observed in the case of a catalyst in which 80Fe-20Co-20Al catalyst was hydrogenated at 350 ° C and 400 ° C. In the case of a catalyst reduced to 350 ° C, The reduction of the active metal was lower than that of one catalyst and the peak intensity was lower.

As a result of the temperature-reduction characteristics analysis (TPR) of FIG. 7, in the catalyst having 61 to 99 parts by weight and 1 to 39 parts by weight of iron and cobalt forming cobalt ferrite, the formation of cobalt ferrite was increased as the content of Co was increased, Was shifted to low temperature.

As a result of analyzing the BET pore characteristics of FIG. 8, the adsorption amount of N ₂ was increased due to the increase of porosity due to the increase of the content of Co in the catalyst, the hysteresis distribution shifted toward higher relative pressure and the distribution of pore diameter was higher As shown in Fig. The specific surface area of the iron - cobalt complex catalyst was larger than that of the catalyst prepared only with iron or cobalt, and the pore volume tended to increase as the content of Co increased.

Claims (20)

A method for producing a synthetic natural gas having a composition capable of exhibiting a high heating value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ ,
Based on 100 parts by weight of iron and cobalt as active metals, 61 to 99 parts by weight and 1 to 39 parts by weight of iron and cobalt, respectively, in the presence of Co and Fe-containing catalysts containing cobalt ferrite of spinel structure, Wherein the selectivity of methane in stage a is 40-80 carbon mole% and the selectivity of C2-C4 hydrocarbon is in the range of 20-60 carbon mole% , And the ratio of paraffins in the C2-C4 hydrocarbons ranges from 90 to 100 carbon%. The method of claim 1, wherein step (a) is carried out simultaneously with the Fischer-Tropsh synthesis reaction and the methanation reaction. The method of claim 1, wherein the active metal in the catalyst is iron oxide, cobalt oxide, iron, cobalt, iron-cobalt oxide and iron-cobalt alloy or mixtures thereof. The process of claim 3, wherein the iron oxide that is an active metal is Fe ₂ O ₃ , Fe ₃ O ₄ , Wherein the cobalt oxide is CoO, Co ₃ O ₄ , or both. 3. The method of claim 1, further comprising reducing the catalyst in a hydrogen atmosphere at a temperature ranging from 250 to 600 &lt; 0 &gt; C before or after step a. The process according to claim 1, wherein the catalyst has a specific surface area of 70 to 120 m ² / g and an average particle size of pores of 7 to 30 nm. The process according to claim 1, wherein the catalyst has a conversion rate in the range of 90 to 100 carbon mole% under reaction conditions of 350 ° C, 30 atm and 6000 ml / g _cat.h space. delete The process according to claim 1, wherein the synthetic natural gas is methane: C2-C4 paraffin (molar ratio) = 1: 0.5 to 1. The process of claim 1, wherein the H ₂ / CO ratio in the feed gas in step a is 1.5 to 3.5. The method according to claim 1, wherein the reaction temperature in step a is 250 to 400 ° C., the reaction pressure is 20 to 40 bar, and the space velocity is 1000 ml / g _cat · h to 10000 ml / g _cat · h . The method according to claim 1, wherein the carbon monoxide-containing feed gas in step a is a syngas produced by gasifying coal, biomass, or carbon-containing waste or purified gas therefrom. As a catalyst for the production of synthetic natural gas having a composition capable of exhibiting high calorific value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ ,
Iron and cobalt are contained in an amount of 61 to 99 parts by weight and 1 to 39 parts by weight, respectively, based on 100 parts by weight of iron and cobalt, which are active metals, and contain cobalt ferrite having a spinel structure, Characterized in that the selectivity of C2-C4 hydrocarbons is in the range of 20 to 60 carbon mole% and the proportion of paraffins in C2-C4 hydrocarbon is in the range of 90 to 100 carbon mole% And a catalyst for simultaneous methanation. 14. Catalyst according to claim 13 characterized in that it is intended for the production of synthetic natural gas containing methane and C2-C4 paraffins from hydrogen and carbon monoxide. 14. Catalyst according to claim 13, characterized in that the active metal is iron oxide, cobalt oxide, iron, cobalt, iron-cobalt oxide and iron-cobalt alloy or mixtures thereof. The method of claim 15, wherein the active metal of iron oxide is _{Fe 2 O 3, Fe 3 O} 4, or both, Wherein the cobalt oxide is CoO, Co ₃ O ₄ , or both. 14. The catalyst according to claim 13, wherein the catalyst has a specific surface area of 75 to 150 m &lt; ² &gt; / g and an average pore size of 4 to 8 nm. 14. Catalyst according to claim 13, characterized in that the catalyst has a conversion of from 90 to 100 carbon% by mol in the reaction conditions of 350 DEG C, 30 atm and 6000 ml / g _cat. H space velocity. 1. A method for producing Fe and Co containing catalysts for producing synthetic natural gas having a high heating value of 11,000 Kcal / Nm ³ to 13,000 Kcal / Nm ³ ,
A first step of preparing a precursor solution by mixing an Fe-based precursor and a Co-based precursor so that iron and cobalt are 61 to 99 parts by weight and 1 to 39 parts by weight, respectively, based on 100 parts by weight of iron and cobalt;
A second step of preparing a mixed solution of a precipitant and distilled water;
A third step of mixing the solution obtained in the first step with the solution obtained in the second step;
A fourth step of precipitating and filtering the mixed solution obtained in the third step; And
The filtrate obtained in the fourth step is dried and calcined at 300 to 700 ° C to prepare a catalyst containing a cobalt ferrite having a spinel structure, having a specific surface area of 70 to 120 m ² / g and an average pore size of 7 to 30 nm Wherein the selectivity of methane to synthetic natural gas is 40-80 carbon mole%, the selectivity of C2-C4 hydrocarbon is 20-60 carbon mole%, the ratio of paraffins in C2-C4 hydrocarbon Is in the range of 90 to 100 carbon mole%. The catalyst production process according to claim 19, wherein the water content of the filtrate obtained in the fourth step is 50 to 80 wt%.

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