KR101276018B1 - Catalyst for fischer―tropsch process and method for preparing the same - Google Patents

Abstract

Fischer-Tropsch process catalyst according to one aspect of the present invention can increase the basicity of the catalyst surface by including sodium (Na) and sodium hydroxide (NaOH) as a promoter. As a result, the carbide forming reaction can be accelerated to increase the production of long chain hydrocarbons such as wax. In addition, the Fischer-Tropsch process catalyst according to one side of the present invention is reduced co-precipitation method under the condition that the synthesis gas (CO + H ₂ ) is present even at a relatively low temperature of 350 ℃ ~ 400 ℃ It may have similar activity as compared to the catalyst prepared by.

Description

Fischer-Tropsch process catalyst and preparation method thereof

Fischer-Tropsch process catalysts and methods for their preparation are disclosed. More specifically, a catalyst for the Fischer-Tropsch process and a method for preparing the same are disclosed which can improve the selectivity to the wax product produced by the Fischer-Tropsch reaction.

Recently, as oil prices have prolonged, interest in the process of producing synthetic petroleum from coal by replacing petroleum as a raw material for transportation fuel or the petrochemical industry is increasing.

The study of Fischer-Tropsch Synthesis, the hydrogenation of carbon monoxide, remained stagnant until the early 1970s, and then, after the petroleum surge, Fischer-Tropsch synthesis became of interest.

There are many important technologies in the CTL process, such as coal gasification and syngas purification, but the Fischer-Tropsch synthesis reaction for synthesizing petroleum from syngas is a key.

The Fischer-Tropsch synthesis process used to produce synthetic oil from syngas (CO + H ₂ ) produces a variety of products depending on the composition of the syngas and the catalyst used.

Generally, the Fischer-Tropsch synthesis process using a synthesis gas having a H ₂ / CO ratio of 2 or more generates a lot of hard hydrocarbons, and the Fischer-Tropsch synthesis process is performed using a synthesis gas having a H ₂ / CO ratio of 2 or less. Gasoline (C ₅ to C ₁₁ ), diesel (C ₁₂ to C ₁₈ ), wax ( _greater than C ₂₄ ), etc., are prepared when performed.

As the catalyst used according to the H ₂ / CO ratio, an FT catalyst based on Fe or Co is used on a commercial scale. In addition, the synthesis conditions can be varied to produce various chemicals (hydrocarbons, alcohols, ethers, acetic acid, etc.).

Fischer-Tropsch synthesis reaction produces hydrocarbons and higher alcohols from syngas (CO + H ₂ ), using iron or cobalt catalysts at a reaction temperature of 200 ° C to 350 ° C and a pressure of 10 to 30 atmospheres. Exothermic reaction. The basic scheme of the Fischer-Tropsch synthesis reaction is shown in Scheme 1 below.

[Reaction Scheme 1]

CO + 2H ₂ ↔-(CH ₂ )-+ H ₂ O, ΔH (227 ° C) = -165 kJ / mol

The main product of the above reaction is a paraffinic hydrocarbon, α-olefin and alcohol may be additionally produced, and the reaction scheme representing the process of forming each product is shown in Schemes 2 to 4. Scheme 2 is a reaction scheme in which n-paraffins are prepared, Scheme 3 is a reaction scheme in which n-olefins are prepared, and Scheme 4 is a reaction scheme in which alcohols are prepared.

[Reaction Scheme 2]

nCO + (2n + 1) H ₂ ↔ C _n H _{2n +2} + nH ₂ O

Scheme 3

nCO + 2nH ₂ ↔ C _n H _2n + nH ₂ O

[Reaction Scheme 4]

nCO + 2nH ₂ ↔ C _n H _{2n +1} OH + (n-1) H ₂ O

In the Fischer-Tropsch synthesis reaction, in addition to the above basic reaction, methanation reaction (Scheme 5), water gas shift reaction (Scheme 6), and Budadoure reaction (Scheme 7) occur additionally. In view of the formation of a liquid product of 5 or more (C _{5 +} ), the methanation reaction is preferably suppressed as much as possible.

Scheme 5

CO + 3H ₂ ↔ CH ₄ + H ₂ O, ΔH (227 ° C) = -215 kJ / mol

[Reaction Scheme 6]

CO + H ₂ O ↔ CO ₂ + H ₂ , ΔH (227 ° C) = -40 kJ / mol

[Reaction Scheme 7]

2CO ↔ C + CO ₂ , △ H (227 ℃) = -134 kJ / mol

In particular, in the case of the iron catalyst, in addition to the basic reaction shown in Scheme 1, it is known to exhibit a significantly higher activity in Scheme 6, which is a water gas shift reaction. This can be a very big advantage considering that the composition ratio of H _{2 to} CO of syngas that can be supplied through coal gasification is lower than the stoichiometric ratio (H ₂ /CO=2.0).

In addition, in the case of the iron catalyst, according to the basicity of the surface (carbide) can be formed according to the reaction scheme 8, the reaction of C and the iron atoms formed through the reaction scheme 7, which is a Buda reaction, which has the effect of promoting the chain growth of hydrocarbons It is known.

[Reaction Scheme 8]

C + xFe ↔ Fe _x C

The iron catalyst for the low temperature Fischer-Tropsch process is mainly produced by precipitation, and contains components such as copper (Cu), potassium (K), and silicon dioxide (SiO ₂ ). Here, Cu serves to increase the reducing power of the Fe-based catalyst, K increases the basicity of the catalyst surface, SiO ₂ serves as a binder. In addition, the Fe-based catalyst must be reduced with hydrogen or syngas (CO + H ₂ ) before the Fischer-Tropsch synthesis reaction.

A catalyst for the Fischer-Tropsch process and a method for preparing the same are provided which can improve the selectivity to the wax product produced by the Fischer-Tropsch reaction.

The catalyst for Fischer-Tropsch process according to an embodiment of the present invention includes an iron (Fe) compound as an active material, sodium (Na) and sodium hydroxide (NaOH) as a promoter, and a carrier.

In the Fischer-Tropsch process catalyst according to one aspect of the present invention, 100 parts by weight of the carrier, 5 to 20 parts by weight of sodium (Na), 5 to 20 parts by weight of the sodium hydroxide (NaOH), and the iron (Fe) ) 1 to 50 parts by weight of the compound.

In the Fischer-Tropsch process catalyst according to one side of the present invention, the carrier may be a material selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ .

Fischer-Tropsch process catalyst manufacturing method according to another embodiment of the present invention, the step of firing the carrier to remove the water and foreign matter adsorbed on the surface of the carrier, the step of stirring the calcined carrier in a nitrogen atmosphere Preparing a molten impregnated carrier by adding sodium (Na) and sodium hydroxide (NaOH) to the stirred carrier, supporting an iron precursor and a copper precursor on the molten impregnated carrier, and the iron precursor and copper Drying and calcining the carrier on which the precursor is supported.

In the method for preparing a catalyst for Fischer-Tropsch process according to one side of the present invention, 5 to 20 parts by weight of the sodium (Na) and 5 to 20 parts by weight of the sodium hydroxide (NaOH) are added to 100 parts by weight of the carrier. Can be.

In the method for preparing a catalyst for Fischer-Tropsch process according to one side of the present invention, the carrier may be a material selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ .

In the method for preparing a catalyst for Fischer-Tropsch process according to one side of the present invention, the iron precursor may be a material selected from the group consisting of iron nitrate, iron chloride, iron phosphate, iron fluoride and iron bromide.

In the method for preparing a catalyst for Fischer-Tropsch process according to one side of the present invention, the copper precursor may be a material selected from the group consisting of copper sulfate, copper chloride, copper nitrate, copper carbonate, copper bromide and copper fluoride.

Fischer-Tropsch process catalyst according to one aspect of the present invention can increase the basicity of the catalyst surface by including sodium (Na) and sodium hydroxide (NaOH) as a promoter. As a result, the carbide forming reaction can be accelerated to increase the production of long chain hydrocarbons such as wax.

In addition, the Fischer-Tropsch process catalyst according to one side of the present invention is reduced co-precipitation method under the condition that the synthesis gas (CO + H ₂ ) is present even at a relatively low temperature of 350 ℃ ~ 400 ℃ It may have similar activity as compared to the catalyst prepared by.

1 shows the conversion of reactants and syngas over time on a stream.

Hereinafter, the Fischer-Tropsch process catalyst and its preparation method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The catalyst for Fischer-Tropsch process according to an embodiment of the present invention includes an iron (Fe) compound as an active material, sodium (Na) and sodium hydroxide (NaOH) as a promoter, and a carrier.

For the catalyst used in the Fischer-Tropsch reaction, there are various preparation methods such as coprecipitation and supporting method, and there are various materials used as active materials of such a catalyst. The activity of the catalyst in the Fischer-Tropsch reaction is very important because it directly affects the yield of the reaction product. The active materials used in the Fischer-Tropsch synthesis reaction include iron (Fe), cobalt (Co), nickel (Ni), and ruthenium (Ru), but iron (Fe) and cobalt (Co) catalysts are commercially available. Mainly used. In particular, iron-based catalysts may be useful for producing long chain hydrocarbons.

In one side of the present invention, the active material may include an iron (Fe) compound. The iron compound may exist in the form of Fe ₂ O ₃ in the pores of the carrier. The iron compound may be included in an amount of 1 to 50 parts by weight based on 100 parts by weight of the carrier. The iron compound undergoes a reduction process (which is an activation process of the catalyst) before the Fischer-Tropsch synthesis reaction, and the Fe ₂ O ₃ form of the iron compound may be reduced to Fe ₃ O ₄ form or metallic iron (Fe).

Metallic Fe reacts with carbon (C) through a carbide forming reaction to form Fe _x C, and Fe _x C promotes the chain growth of hydrocarbons during the Fischer-Tropsch synthesis reaction, thereby forming a long chain wax material. Can increase the production of

In one aspect of the present invention, when the iron compound is contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the carrier, the iron compound may be highly dispersed in the pores inside the carrier to support the Fischer-Tropsch synthesis reaction excellent activity Can be represented. In addition, when the iron compound is less than 1 part by weight, there is a limit to exhibiting high activity due to the limitation of the number of active points, and when the iron compound is larger than 50 parts by weight, the pore structure inside the carrier is recessed or blocked, thereby improving the characteristics of the carrier according to the high surface area. A phenomenon in which the activity of the catalyst is lowered is not shown.

Sodium (Na) and sodium hydroxide (NaOH) act as a promoter, and sodium (Na) and sodium hydroxide (NaOH) can increase the basicity of the catalyst surface. In the iron-based catalyst according to one side of the present invention, each of sodium (Na) and sodium hydroxide (NaOH) based on 100 parts by weight of the carrier may be included in 5 to 20 parts by weight.

In the case of the iron-based catalyst in the Fischer-Tropsch synthesis reaction, depending on the basicity of the catalyst surface, the carbon and iron atoms generated through the Buda reaction may react with the carbide forming reaction. As described above, this carbide formation reaction can promote chain growth of hydrocarbons to facilitate the synthesis of longer chain hydrocarbon products, such as waxes.

Accordingly, the catalyst according to one aspect of the present invention includes sodium (Na) and sodium hydroxide (NaOH) as cocatalysts to increase the basicity of the surface of the catalyst to generate a carbide-forming reaction, so that the wax material of the long chain structure And the like can increase the production.

In one aspect of the present invention may include sodium (Na) and sodium hydroxide (NaOH) as a promoter. Sodium (Na) and sodium hydroxide (NaOH) may be included in 5 to 20 parts by weight based on 100 parts by weight of the carrier. When sodium (Na) and sodium hydroxide (NaOH) are less than 5 parts by weight, the effect of increasing the surface basicity with the addition of sodium (Na) and sodium hydroxide (NaOH) is insignificant. When the Fischer-Tropsch reaction is strong, a lot of carbon deposition reaction according to the above-mentioned Scheme 7 may occur, and thus the catalyst may be easily deactivated.

Copper (Cu) serves to increase the reducing power of the iron (Fe) -based catalyst. That is, copper may increase the activity of the catalyst by promoting the process of activating the catalyst. In addition, copper serves to lower the reduction temperature of the catalyst on the iron-based catalyst.

The carrier can improve the dispersion of the catalyst and enhance the stability of the catalyst. In the catalyst according to one aspect of the invention, the carrier may be a material selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ .

Hereinafter, a method for preparing a catalyst according to an embodiment of the present invention will be described. In the present specification, the normal temperature means about 20 ° C. to 25 ° C., and the normal pressure means about 1 atmosphere.

Fischer-Tropsch process catalyst manufacturing method according to an embodiment of the present invention, the step of firing the carrier to remove the water and foreign matter adsorbed on the surface of the carrier, the step of stirring the calcined carrier in a nitrogen atmosphere Preparing a molten impregnated carrier by adding sodium (Na) and sodium hydroxide (NaOH) to the stirred carrier, supporting an iron precursor and a copper precursor on the molten impregnated carrier, and the iron precursor and copper Drying and calcining the carrier on which the precursor is supported.

First, a process of baking the carrier is performed to remove moisture and foreign matter adsorbed on the surface of the carrier. The process of calcining the carrier includes raising the temperature to 300 ° C. to 400 ° C. at room temperature, and then maintaining the temperature at 300 ° C. to 400 ° C. for 2 hours to 4 hours, and then cooling the temperature to room temperature.

Thereafter, the carrier in the form of powder from which water and foreign substances have been removed is stirred in an autoclave reactor. In other words, the carrier is removed from the water and foreign matter in the autoclave reactor flows nitrogen (N ₂ ) gas for 30 minutes to 1 hour at a rate of 10 ml / min. After flowing enough nitrogen, when the inside of the autoclave becomes a nitrogen atmosphere, the temperature was raised to 350 ° C., and then slowly stirred at 50 to 100 RPM and maintained at the same temperature for 2 to 3 hours.

Thereafter, sodium (Na) and sodium hydroxide (NaOH) were introduced by 5 to 20 parts by weight based on 100 parts by weight of the carrier into the autoclave from a special sample holder installed in the autoclave reactor, and again 2 to 3 Stirring for a time to produce a melt impregnated carrier.

Thus, an iron precursor and a copper precursor are supported on a carrier impregnated with sodium (Na) and sodium hydroxide (NaOH), and then dried and calcined to prepare an iron-based catalyst applicable to the Fischer-Tropsch process.

In the method for preparing a catalyst according to one side of the present invention, the carrier may be a material selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ .

The iron precursor may be a material selected from the group consisting of iron nitrate, iron chloride, iron phosphate, iron fluoride and iron bromide.

The copper precursor may be a material selected from the group consisting of copper sulfate, copper chloride, copper nitrate, copper carbonate, copper bromide, and copper fluoride.

Example 1

After preparing 50 g of silicon dioxide (SiO ₂ ), a firing process as described above is performed to remove moisture and foreign substances adsorbed on the surface of SiO ₂ . That is, the calcination process means a process of raising the temperature to 300 ° C. to 400 ° C. at room temperature, and then maintaining the temperature at 300 ° C. to 400 ° C. for 2 hours to 4 hours, and then cooling to room temperature. Thereafter, the SiO ₂ carrier from which moisture and foreign substances were removed is placed in an autoclave reactor, and nitrogen (N ₂ ) gas is flowed for 30 minutes to 1 hour at a rate of 10 ml / min. After flowing enough nitrogen, when the inside of the autoclave becomes a nitrogen atmosphere, the temperature was raised to 350 ° C., and then slowly stirred at 50 to 100 RPM and maintained at the same temperature for 2 to 3 hours.

Thereafter, 2.5 g of sodium (Na) and sodium hydroxide (NaOH) were respectively introduced into the autoclave from a special sample holder installed in the autoclave reactor, and then stirred for 2 to 3 hours to melt the impregnated carrier. Manufacture.

Subsequently, 92.7 g of Fe (NO ₃ ) ₃ as an iron precursor and 2.35 g of Cu (NO ₃ ) ₂ were supported as a copper precursor on a carrier impregnated with sodium (Na) and sodium hydroxide (NaOH), followed by 2 at 100 ° C. Dry for hours and calcined at 400 ° C. for 8 hours to produce an iron-based catalyst applicable to the Fischer-Tropsch process. The composition of the catalyst prepared according to one side of the present invention is 20Fe / 5Na / 5NaOH / 1Cu / 79SiO ₂ . That is, the catalyst prepared according to one side of the present invention, when the total composition is 100, the weight part of the iron component is 20, the weight part of sodium and sodium hydroxide are each 5, the weight part of copper is 1, the weight of silicon dioxide The addition accounts for 79.

1 shows the conversion of reactants and syngas over time on a stream.

First, Figure 1 shows a graph of the conversion rate for the case of using the iron-based catalyst prepared according to one side of the present invention, the catalyst is 20Fe / 5Na / 5NaOH / 1Cu / 79SiO ₂ as described above. The vertical axis (conversion,%) represents the conversion rate, and the horizontal axis represents time on stream (TOS). In addition, the process conditions in FIG. 1 have a value of H ₂ / CO of 1, a reduction temperature of 350 ° C, and a reaction temperature of 275 ° C.

In the graph of Figure 1, CO conv represents the total conversion of the reactant CO, H ₂ conv represents the total conversion of the reactant H ₂ , Syngas conv represents the conversion of the synthesis gas (CO + H ₂ ) CO The median value of conv and H ₂ conv.

In addition, in the graph of FIG. 1, CO to CO ₂ conv represents a conversion rate of CO converted to CO ₂ , and the smaller the value, the better the performance of the catalyst. CO to HC conv shows that CO is a hydrocarbon (Hydrocarbon). The conversion rate is converted into. The higher the value, the better the catalyst performance.

Referring to FIG. 1, it can be seen that the conversion in the reaction in which the hydrocarbon (HC) is generated is greater than the conversion in the reaction in which the carbon dioxide (CO ₂ ) is produced. From this, when using the catalyst prepared according to one side of the present invention it is possible to maximize the desired reaction by increasing the conversion rate of the carbon monoxide is converted hydrocarbon. That is, the catalyst according to one side of the present invention may promote the carbide formation reaction to increase the production of long chain hydrocarbons, such as wax.

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, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (8)

A catalyst for the Fischer-Tropsch process comprising an iron (Fe) compound as an active substance, sodium (Na) and sodium hydroxide (NaOH) as a promoter, and a carrier.
The method of claim 1,
100 parts by weight of the carrier;
5 to 20 parts by weight of the sodium (Na);
5 to 20 parts by weight of the sodium hydroxide (NaOH); And
1 to 50 parts by weight of the iron (Fe) compound;
Fischer-Tropsch process catalyst comprising a.
The method of claim 1,
The carrier is a catalyst for Fischer-Tropsch process is a material selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ .
Calcining the carrier to remove moisture and foreign matter adsorbed on the surface of the carrier;
Stirring the calcined carrier under a nitrogen atmosphere;
Preparing a molten impregnated carrier by adding sodium (Na) and sodium hydroxide (NaOH) to the stirred carrier;
Supporting an iron precursor and a copper precursor on the melt-impregnated carrier; And
Drying and firing the carrier on which the iron precursor and the copper precursor are supported;
Fischer-Tropsch process for producing an iron-based catalyst comprising a process.
5. The method of claim 4,
5 to 20 parts by weight of the sodium (Na) and 5 to 20 parts by weight of the sodium hydroxide (NaOH) are added to 100 parts by weight of the carrier.
5. The method of claim 4,
The carrier is a method for producing a catalyst for Fischer-Tropsch process is a material selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ .
5. The method of claim 4,
The iron precursor is a method for producing a catalyst for Fischer-Tropsch process is a material selected from the group consisting of iron nitrate, iron chloride, iron phosphate, iron fluoride and iron bromide.
5. The method of claim 4,
Wherein said copper precursor is a material selected from the group consisting of copper sulfate, copper chloride, copper nitrate, copper carbonate, copper bromide, and copper fluoride.

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