KR101968297B1 - Catalyst for producing Synthetic-Natural-Gas of higher heating level and Use thereof - Google Patents

Abstract

The present invention relates to a process for the production of a catalyst for catalytic reduction of carbon monoxide from carbon monoxide to carbon monoxide in the presence of Ni and Fe containing a magnetite of spinel structure and 80 to 95 parts by weight and 5 to 20 parts by weight of iron and nickel, And a C2-C4 paraffin-containing synthetic natural gas. 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 It is possible to produce high-calorific synthetic natural gas of ~ 19,000 Kcal / Nm ³ , and it is a catalyst that can simplify the process compared to existing natural gas synthesis process due to high C1-C4 productivity.

Description

Catalysts for the production of high calorific value synthetic natural gas and their uses

TECHNICAL FIELD The present invention relates to a catalyst for producing high calorific value synthetic natural gas and a method for producing the same and a use thereof. 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, a large part of energy in the sample is converted into gas containing chemical energy such as carbon monoxide or hydrogen by the gasification reaction, and even if the gas is rapidly cooled, the chemical energy of the gas is kept as it is. The energy can be reacquired.

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 composition capable of exhibiting a high heating amount of 11,000 Kcal / Nm ³ to 19,000 Kcal / Nm ^{3, comprising the steps} of: Comprising the step of producing a synthetic natural gas containing methane and C2-C4 paraffins from carbon monoxide in the presence of Ni and Fe containing catalysts each containing 80 to 95 parts by weight and 5 to 20 parts by weight of nickel and containing magnetite of spinel structure ≪ / RTI >

A second aspect of the present invention is a process for the preparation of a composition comprising 11,000 Kcal / Nm < ³ > ~ 19,000 Kcal / Nm ³ in a synthesis gas production catalyst of the following composition exhibiting calorific, based on the active metal of iron and nickel on 100 parts by weight, iron and nickel are respectively 80 to 95 parts by weight and 5 to 20 parts by weight Ni and Fe < RTI ID = 0.0 > , A catalyst for simultaneous FT synthesis and methanation.

A third aspect of the present invention is 11,000 Kcal / Nm ³ A method of manufacturing a ~ 19,000 Synthesis of the following composition exhibiting calorific of Kcal / Nm ³ natural gas production Ni and Fe-containing catalyst, based on iron and nickel of 100 parts by weight of iron and nickel, each 80 to 95 parts by weight And 5 to 20 parts by weight of a Fe precursor and a Ni precursor to prepare a precursor solution; 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 450 to 650 ° C to prepare a catalyst having a specific surface area of 75 to 150 m ² / g and an average particle size of pores of 4 to 8 nm, containing magnetite of spinel structure And a fifth step of preparing the catalyst.

Hereinafter, the present invention will be described in detail.

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

(i) In the case of the Fe single metal catalyst, the exothermic amount is very high, but since the CO to CO ₂ conversion is high and the SNG yield is low, it is not suitable as a catalyst for SNG synthesis.

(ii) The CO conversion rate was close to 100% in all composition ratios and the CO to CO ₂ conversion was decreased by the addition of Ni active metal.

(iii) CH ₄ selectivity increased more than two fold by addition of Ni active metal, and showed about 90% CH ₄ selectivity when Ni ratio was more than 20% of total active metal. The C ₂ -C ₄ selectivity and C ₅₊ selectivity were greatly reduced by the addition of Ni active metal, and the C ₂ -C ₄ hydrocarbons Paraffin selectivity reached 100% by Ni addition.

(iv) The SNG yield was increased by decreasing the C ₅₊ selectivity of hydrocarbon selectivity depending on the amount of Ni added and added. However, the Fe: Ni 50:50 and 80:20 catalysts showed very low calorific value I found a problem. For example, when Ni was added, the calorific value was greatly reduced from 19,000 Kcal / Nm ³ to 10,000 Kcal / Nm ³ , and there was no significant difference between Fe: Ni at 50:50 and 80:20. That is, when the proportion of Ni in the active metal is 20% or more, the amount of heat generated is low due to the high CH ₄ selectivity and the low C ₂ -C ₄ selectivity.

(v) The SNG calorific value of Fe: Ni of 95: 5 was found to be 14,300 Kcal / Nm ³ higher than that of 50:50 and 80:20. When the ratio of iron in the active metal is less than 80%, it has been found that the methanation reaction by Ni predominates and the C2-C4 hydrocarbon selectivity of the product is lowered and the calorific value is lowered.

The present invention is based on this finding, and it is an object of the present invention to provide a process for producing a Ni-Fe-containing catalyst in which the Fischer-Tropsh synthesis reaction and the methanation reaction are simultaneously carried out by controlling the Ni ratio in the active metal to less than 20 wt% And is characterized in that a high calorific value synthetic natural gas having a composition ratio of C ₂ -C ₄ selectivity is produced.

The Ni- and Fe-containing catalyst according to the present invention is characterized in that iron and nickel 80 to 95 parts by weight and 5 to 20 parts by weight Weight part, nickel is not the main catalyst but iron is the main catalyst, and 11,000 Kcal / Nm ³ It is possible to produce synthetic natural gas with a composition capable of exhibiting a high heating value of ~ 19,000 Kcal / Nm ³ .

The active metal in the catalyst may be iron oxide, nickel oxide, iron, nickel, iron-nickel alloy or a mixture thereof. In addition, the catalyst may include a spinel structure of magnetite in an oxidized state, and a spinel structure of magnetite mainly in a reduced state.

The Ni 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 Ni- and Fe-containing catalyst according to the present invention may have a specific surface area of 75 to 150 m ² / g and an average particle size of pores of 4 to 8 nm.

Fischer-Tropsh The Fe and Ni-containing catalysts simultaneously reacting with the Fischer-Tropsh synthetic and methanation reaction can increase the C2 to C4 composition ratio in the SNG through the Fischer-Tropsh synthesis reaction in the SNG synthesis. 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.

The synthetic natural gas produced by the catalyst according to the present invention may have a composition that exhibits a high calorific value of 11,000 Kcal / Nm ³ to 19,000 Kcal / Nm ³ . In one embodiment, the synthetic natural gas may be methane: C2-C4 paraffin (molar ratio) = 1: 0.05-0.5.

In accordance with the present invention, 11,000 Kcal / Nm &lt; ³ &gt; A method of producing a Ni- and Fe-containing catalyst for producing a synthetic natural gas having a composition capable of exhibiting a high calorific value of 19,000 Kcal / Nm ³ ,

A first step of preparing a precursor solution by mixing an Fe-based precursor and a Ni-based precursor so that iron and nickel are 80 to 95 parts by weight and 5 to 20 parts by weight, respectively, based on 100 parts by weight of iron and nickel;

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 450 to 650 ° C to prepare a catalyst having a specific surface area of 75 to 150 m ² / g and an average particle size of pores of 4 to 8 nm containing magnetite of spinel structure And a fifth step.

Here, it is deduced that the pore structure and the phase specificity appear depending on the composition ratio of the active metal and the firing temperature.

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

The catalyst according to the present invention may further contain a cocatalyst capable of easily controlling the catalyst performance. Non-limiting examples of the cocatalyst component include Mn, Cu, Co, Zn, K, Ce, . Increase of selectivity of methane and paraffin for Cu and Co co-catalysts, enhancement of stability of Fe-active metals for Mn and enhancement of hydrocarbon selectivity for catalyst stability and high calorie SNG synthesis, .

The cocatalyst component is preferably maintained at 0.5 to 5 parts by weight based on 100 parts by weight of Fe and Ni metals to be 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 the use of an alumina support with other nickel / 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%.

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 calorific value of synthetic natural gas tended to decrease from 14,300 Kcal / Nm ³ to 12,300 Kcal / Nm ³ up to 550 ° C as the catalytic firing temperature increased, and again to 14,400 Kcal / Nm ³ above 600 ° C It looked. The SNG yield showed a tendency to be opposite to the heating value, and it was the highest as 70% or more in the calcination catalyst at 550 ° C.

The specific surface area of the final product obtained through the above processes is preferably 75 to 150 m ² / g, and the average particle diameter of the pores is preferably 4 to 8 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 form of the final product may be iron oxide, nickel oxide, iron or nickel aluminate, and may include magnetite of spinel structure. In addition, the activated (reduced) catalyst can be made of iron oxide, nickel oxide, iron, nickel, iron-nickel alloy. At this time, the iron oxide as the active metal is Fe ₂ O ₃ , Fe ₃ O ₄ , or both, Nickel oxide may be any of NiO, Ni ₂ O _3, or both, it may be composed of mainly magnetite in spinel structure.

The composition of the final product is preferably 80 to 95 parts by weight and 5 to 20 parts by weight, respectively, based on 100 parts by weight of iron and nickel, which are active metals.

When the composition of the iron is below the lower limit, the methanation reaction by Ni predominates and the C2-C4 hydrocarbon selectivity of the product is lowered to lower the calorific value, and when the upper limit is exceeded, the Fe characteristic is dominant, The SNG yield due to the reaction is lowered and olefin selectivity is high, which is not preferable.

When the composition of the nickel is below the lower limit, the methanation reaction is insufficient and SNG yield is lowered. When the upper limit is exceeded, the FT synthesis reaction is insufficient and the product has a low C2-C4 hydrocarbon selectivity.

The present invention is 11,000 Kcal / Nm ³ A method for producing a synthetic natural gas having a composition capable of exhibiting a high heating value of 19,000 Kcal / Nm ³ ,

A method for producing a catalyst for catalytic reduction of methane and C2-C8 hydrocarbons from carbon monoxide in the presence of Ni and an Fe-containing catalyst containing 80 to 95 parts by weight and 5 to 20 parts by weight of iron and nickel, respectively, and containing magnetite of spinel structure, C4 paraffin-containing synthetic natural gas. &Lt; RTI ID = 0.0 &gt; A &lt; / RTI &gt;

The method may further include reducing the catalyst in a hydrogen atmosphere at a temperature ranging from 300 to 600 ° 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 Ni-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 33-82 carbon mole%, the selectivity of C2-C4 hydrocarbon is 3-17 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 for the reaction after being reduced in a hydrogen atmosphere at a temperature range of 300 to 600 ° C in a fixed bed, a fluidized bed, and a slurry reactor.

In the step a, the reaction temperature is preferably 300 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.

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 33 to 82 carbon mole% of methane and 3 to 17 carbon mole% of C2-C4 hydrocarbon. The ratio of paraffins in C2-C4 hydrocarbons is in the range of 90-100 carbon mole%, and by-products C5 or higher hydrocarbons, specifically C5-C12 gasoline oil fractions, range from 6 to 13 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.

FIG. 1 shows the conversion and hydrocarbon selectivity of the catalyst prepared in Example 1 and Comparative Examples 1 to 3.
FIG. 2 shows the amounts of heat generated and yields of SNG by the catalyst prepared in Example 1 and Comparative Examples 1 to 3. FIG.
FIGS. 3, 4, and 5 are XRD, RTP, and BET pore characterization results of the catalysts prepared in Examples 2 to 5 and Comparative Example 4, respectively.
6 shows conversion rates and selectivities of hydrocarbons by the catalysts prepared in Examples 2 to 5 and Comparative Example 4. FIG.
7 shows the SNG calorific value and yield according to the catalysts prepared in Examples 2 to 5 and Comparative Example 4. Fig.
FIG. 8 shows conversion ratios and hydrocarbon selectivities in Examples 6 and 7 and Comparative Example 5.
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.

< Example  One, Comparative Example  1 to 3> Fe: Ni  High calorific value by ratio Synthetic natural gas  Synthesis Fe- Ni  Manufacture of heterogeneous metal catalysts

The amounts of the metal precursors used in the Fe-Ni catalyst according to the composition shown in Table 1 below were adjusted so that the catalyst compositions were 50 Fe-50 Ni-20 Al, 80 Fe-20 Ni-20 Al, 95 Fe-5 Ni-20 Al and 98 Fe- _{(Fe (NO 3) 3 ·} 9H 2 O), nickel nitrate _{(Ni (NO 3) 2 ·} 6H 2 O) and aluminum nitrate _{(Al (NO 3) 3 ·} 9H 2 O) of a precursor solution by dissolving in 200ml of distilled water .

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-Ni catalyst according to the composition).

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 resulting ferric hydroxide cake was filtered and dried until the water content became 55%. The dried iron hydroxide cake was dried in a drying oven at 110 DEG C for 12 hours and then calcined at 450 DEG C for 4 hours in an air atmosphere in a firing furnace.

X-ray fluorescence analysis (XRF) of the catalyst prepared in the following Table 3 (XRF analysis of Fe-Ni catalyst according to composition) is shown.

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

The prepared catalyst was charged into a 1/2-inch stainless steel fixed bed reactor with 1 g of the catalyst prepared in Example and Comparative Example, reduced under H ₂ atmosphere at 400 ° 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.

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

The CH ₄ selectivity was increased more than two times by the addition of Ni active metal. When the Ni ratio was more than 20% of the total active metal, CH ₄ selectivity was about 90%. The C ₂ -C ₄ selectivity and C ₅₊ selectivity were greatly reduced by the addition of Ni active metal, and the C ₂ -C ₄ hydrocarbons Paraffin selectivity reached 100% by Ni addition.

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 (Ni ratio of active metal less than 20%) having a high degree of C ₂ -C ₄ selectivity is optimum.

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 calorific value was greatly reduced from 19,000 Kcal / Nm ³ to 10,000 Kcal / Nm ³ when Ni was added, and there was no significant difference between Fe: Ni at 50:50 and 80:20. At Fe: Ni of 95: 5, the SNG calorific value was 14,300 Kcal / Nm ^{3, which} was higher than 50:50 and 80:20. SNG yield increased with Ni addition and addition amount. However, the heating value was very low compared with the high SNG yield in case of Fe: Ni 50:50 and 80:20 catalyst, and the heating value was very high in case of catalyst not containing Ni, The yield was very low.

Therefore, Fe single metal catalysts are not suitable as SNG synthesis catalysts because of high CO to CO ₂ conversion and low SNG yield. When the proportion of Ni in the active metal is more than 20%, 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.

<Examples 2 to 5> Production of Fe-Ni hetero metal catalyst for synthesis of high calorific value synthetic natural gas according to firing temperature

(Fe (NO ₃ ) ₃ .9H ₂ O), nickel nitrate (Ni (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.

The precursor solution was added to a solution of 99.5% potassium carbonate (K ₂ CO ₃ ) (38 g) and 300 ml of distilled water under vigorous stirring, the precipitate slurry was stirred at 80 ° C for 3 hours, and the resulting precipitate was filtered And washed several times with 1,000 ml of distilled water. The resulting ferric hydroxide cake was filtered and dried until the water content became 55%. The dried iron hydroxide cake was dried at 110 ° C for 12 hours in a drying oven, and then calcined at 450 ° C, 500 ° C, 550 ° C, 600 ° C and 700 ° C for 4 hours in an air atmosphere in a sintering furnace.

The results of X-ray fluorescence analysis (XRF), X-ray diffraction analysis (XRD), heating-reduction characteristics analysis (TPR) and BET pore characterization of the iron-nickel dissimilar metal catalysts prepared above are shown in Table 4 XRF analysis of the Fe-Ni catalyst according to the present invention) is shown in FIG. 3, FIG. 4, and FIG.

As shown in Table 4, the prepared catalyst had the same XRF analysis and the designed catalyst composition, and no change was observed according to the firing temperature. From the above, it was confirmed that the catalyst can be manufactured in accordance with the designed catalyst composition without changing the calcination temperature by the catalyst production method.

As a result of the XRD analysis of FIG. 3, Fe ₂ O ₃ and Fe ₃ O ₄ , which are oxides of Fe occupying most of the active metal ratio peak NiO peak and aluminate peaks of Fe and Ni were observed. At the calcination temperature above 550 ℃, the peak intensity increased significantly by crystal size increase.

The Fe ₂ O ₃ peak in the XRD peak of the catalyst after reduction was not observed or the intensity was greatly decreased, and the peak indicating Fe ₃ O ₄ was the main peak. In addition, iron metal peak and Fe-Ni alloy peak were observed by catalytic reduction and intensity increased with increasing catalytic firing temperature.

FIG temperature rise of 4 - is the more reduced the characterization (TPR) result, the firing temperature increase increases the Fe-Ni bimetallic oxide and aluminate formed, Fe ₂ O ₃ → Fe ₃ O ₄ reduction peak (340 → 400 ° C.), Fe ₃ O ₄ → Fe & aluminate reduction peak (470 → 700 ° C.) was shifted to high temperature.

As a result of analyzing the BET pore characteristics of FIG. 5, the adsorption amount of catalyst N ₂ decreased and the distribution of hysteresis shifted to a higher relative pressure due to the decrease of porosity due to sintering of the active ingredient with increasing catalytic firing temperature. The specific surface area and the pore volume of the 95Fe-5Ni-20Al catalyst according to the firing temperature shown in Table 5 were decreased with the firing temperature of the catalyst. Particularly, the specific surface area was significantly reduced at 550 ° C or higher. The pore size increased with the calcination temperature of the catalyst. In the pore distribution diagram of FIG. 5, the pore distribution of the catalyst according to each example was shifted from 6 to 12 nm in the range of 2 to 6 nm with increasing calcination temperature.

The prepared catalyst was charged in a 1/2-inch stainless steel fixed bed reactor with 1 g of the catalyst prepared in Examples and Comparative Examples, reduced under H ₂ atmosphere at 400 ° C. for 6 hours, Under the conditions of pressure 30 bar and space velocity 6,000 ml / g _cat · h, synthesis gas as a reactant was injected into the reactor with the H ₂ / CO ratio fixed at 3 to perform SNG synthesis reaction.

FIG. 6 shows the conversion and hydrocarbon selectivity according to Examples and Comparative Examples.

The CO conversion of 95Fe-5Ni-20Al catalyst was close to 100% regardless of the calcination temperature except for the calcination temperature of 700 ℃. However, the calcination catalyst at 700 ℃ showed a significant reduction of CO conversion by the formation of metal-aluminate And the activity of WGS was very high. The CO ₂ to CO ₂ conversion and the C ₅₊ selectivity were the lowest in the calcined catalyst at 550 ℃.

In the case of hydrocarbon selectivity, CH ₄ selectivity increased up to 550 ℃ with increasing catalytic firing temperature, and paraffin selectivity was 100% at all firing temperatures above 550 ℃. In the case of the calcination catalyst at 700 ° C, the high C ₂ -C ₄ selectivity is shown as a roll, which is expected to have a high calorific value, but it is not suitable for the SNG synthesis reaction due to low CO conversion and high WGS activity.

FIG. 7 shows the SNG heating amount and yield according to Examples and Comparative Examples.

The calorific value tended to decrease from 14,300 Kcal / Nm ³ to 12,300 Kcal / Nm ³ up to 550 ° C as the catalyst firing temperature increased, and again to 14,400 Kcal / Nm ³ above 600 ° C Of the total. The SNG yield showed a tendency to be opposite to the heating value, and it was the highest as 70% or more in the calcination catalyst at 550 ° C.

Therefore, when the firing temperature of the catalyst is below 450 ° C., the solvent and organic impurities used in the production process are difficult to completely remove due to firing, the uniform dispersion of the active ingredient and the promoter is lowered and the catalyst strength is weak. And it is suitable as SNG synthesis catalyst due to insufficient decrease of purity due to excessive formation of Fe-aluminate and Ni-Aluminate and insufficient activity and formation of pore structure by sintering when the temperature exceeds 650 ° C not.

< Example  6-7> Fe- Ni  Synthesis gas H of heterogeneous metal catalyst ₂ / SNG Synthesis Reaction Characteristics by CO Ratio

1 g of 95 Fe-5Ni-20Al calcined catalyst of Example 4 at 550 캜 was charged into a 1/2-inch stainless steel fixed bed reactor and subjected to reduction treatment at 400 캜 under an H ₂ atmosphere for 6 hours. Under the conditions of a pressure of 30 bar and a space velocity of 6,000 ml / g _cat · h, the synthesis gas, which is a reactant, was injected into the reactor at an H ₂ / CO ratio of 1 to 3 to perform SNG synthesis reaction.

The conversion and hydrocarbon selectivity according to Examples and Comparative Examples are shown in FIG.

CO conversion and CO to HC conversion increased with increasing H ₂ / CO ratio and CO to CO ₂ conversion decreased with decreasing WGS activity. When the H ₂ / CO ratio is less than 1.5, the conversion of CO to CO ₂ is very high, more than 40%, indicating that the SNG yield is not suitable for SNG synthesis due to low CO to HC conversion.

The CH ₄ selectivity and paraffin selectivity increased with increasing H ₂ / CO ratio and the C2-C4 selectivity decreased. When the H ₂ / CO ratio is less than 1.5, the paraffin selectivity is low, indicating that it is not suitable for high-temperature SNG synthesis.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the scope of protection of the present invention is not limited to the specific embodiments but should be construed as including all embodiments belonging to the claims attached hereto.

Claims (20)

A method for producing a synthetic natural gas having a composition exhibiting a high heating value of methane: C2-C4 paraffin (molar ratio) = 1: 0.05-0.5,
The present inventors have found that in the presence of Ni and Fe containing catalysts each containing 80 to 95 parts by weight and 5 to 20 parts by weight of iron and nickel and containing magnetite of spinel structure based on 100 parts by weight of iron and nickel as active metals, Comprising producing a methane and a C2-C4 paraffin-containing synthetic natural gas from a feed gas contained in a ratio of 1.5 to 3.5 (hydrogen / carbon monoxide). The process according to claim 1, wherein step (a) is carried out simultaneously with the Fischer-Tropsh (FT) synthesis reaction and the methanation reaction. The method of claim 1, wherein the active metal in the catalyst is iron oxide, nickel oxide, iron, nickel, iron-nickel 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 , Nickel oxide is the method that the NiO, Ni ₂ O _3, or both characteristics. 2. The method of claim 1, further comprising reducing the catalyst in a hydrogen atmosphere at a temperature ranging from 300 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 75 to 150 m ² / g and an average pore size of 4 to 8 nm. 2. The process of claim 1, wherein the catalyst has a CO conversion in the range of 90 to 100 carbon mole% under reaction conditions of 350 &lt; 0 &gt; C, 30 atm and 6000 ml / g _cat.h space. The method of claim 1, wherein the selectivity of methane in stage a is 33-82 carbon mole%, the selectivity of C2-C4 hydrocarbon is in the range of 3-17 carbon mole%, the ratio of paraffins in C2- 100 carbon mole%. delete delete The process according to claim 1, wherein the reaction pressure in step a is 20 to 40 bar, the reaction temperature is 300 to 400 ° C, and the space velocity is 1000 ml / g _cat.h to 10000 ml / g _cat.h Feature method. The method according to claim 1, wherein the carbon monoxide and hydrogen-containing feed gas in step a is a syngas produced from gasification of coal, biomass, or carbon-containing waste or purified gas therefrom. A catalyst for the production of synthetic natural gas having a composition exhibiting a high heating value of methane: C2-C4 paraffin (molar ratio) = 1: 0.05 to 0.5 from a feed gas containing carbon monoxide and hydrogen at a ratio of 1.5 to 3.5 (hydrogen / carbon monoxide) as,
Characterized in that it contains 80 to 95 parts by weight and 5 to 20 parts by weight of iron and nickel, respectively, based on 100 parts by weight of iron and nickel, which are active metals, and contains magnetite of spinel structure, FT synthesis And a catalyst for simultaneous methanation. delete 14. Catalyst according to claim 13, characterized in that the active metal is iron oxide, nickel oxide, iron, nickel, iron-nickel 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, Nickel oxide NiO, Ni ₂ O _3, or both, characterized in that the catalyst. 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. The catalyst according to claim 13, wherein the catalyst has a CO conversion in the range of 90 to 100 carbon mole% under reaction conditions of 350 DEG C, 30 atm and 6000 ml / g _cat.h space velocity. (Ni) for the production of a synthetic natural gas having a composition that exhibits a high heating value of methane: C2-C4 paraffin (molar ratio) = 1: 0.05 to 0.5 from a feed gas containing carbon monoxide and hydrogen at a ratio of 1.5 to 3.5 (hydrogen / carbon monoxide) And a method for producing an Fe-containing catalyst,
A first step of preparing a precursor solution by mixing an Fe-based precursor and a Ni-based precursor so that iron and nickel are 80 to 95 parts by weight and 5 to 20 parts by weight, respectively, based on 100 parts by weight of iron and nickel;
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 450 to 650 ° C to obtain a catalyst having a magnetite of spinel structure and having a specific surface area of 75 to 150 m ² / g and an average particle diameter of 4 to 8 nm And a fifth step of producing the catalyst. The catalyst production method according to claim 19, wherein the water content of the filtrate obtained in the fourth step is 50 to 80%.

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