METHOD FOR PRODUCING LIQUID OR SOLID HYDROCARBONS FROM SYNTHESIS GAS VIA FISCHER-TROPSCH SYNTHESIS WHICH DOES NOT CARRY OUT SEPARATE REDUCTION PRE-TREATMENT FOR CATALYST ACTIVATION

Abstract

The present invention relates to a method for producing liquid or solid hydrocarbons from a synthesis gas via Fischer-Tropsch synthesis which does not carry out a separate reduction pre-treatment for catalyst activation. The method for producing liquid or solid hydrocarbons from a synthesis gas using Fischer-Tropsch synthesis according to the present invention comprises: a first step of applying an iron-based catalyst for the Fischer-Tropsch synthesis in which the number of iron atoms in the ferrihydrite phase fraction equals 10 to 100% and the number of iron atoms in the hematite phase fraction equals 0 to 90%, with respect to 100% of the number of the number of iron atoms, to a Fischer-Tropsch synthesis reactor; and a second step of activating the catalyst for the Fischer-Tropsch synthesis by a synthesis gas which is a reactant under the conditions of the Fischer-Tropsch synthesis and carrying out the Fischer-Tropsch synthesis by means of the activated catalyst for the Fischer-Tropsch synthesis. As such, the present invention is capable of efficiently producing liquid or solid hydrocarbons from a synthesis gas via Fischer-Tropsch synthesis, even without a separate reduction pre-treatment.

Claims

1. A method for producing liquid hydrocarbons from a synthesis gas via Fischer-Tropsch synthesis, the method comprising the steps of: a first step of applying an iron-based catalyst for the Fischer-Tropsch synthesis wherein the number of iron atoms in the ferrihydrite phase fraction equals 10 to 100% and the number of iron atoms in the hematite phase fraction equals 0 to 90%, with respect to 100% of the number of iron atoms, to a Fischer-Tropsch synthesis reactor; and a second step of activating the catalyst for the Fischer-Tropsch synthesis by a synthesis gas which is a reactant under the conditions of the Fischer-Tropsch synthesis and carrying out the Fischer-Tropsch synthesis over the activated catalyst for the Fischer-Tropsch synthesis.

2. The method according to claim 1, the Fischer-Tropsch synthesis reactor is a slurry bubble column reactor.

3. The method according to claim 1, the ferrihydrite is FeOOH.nH.sub.2O (0<n<1).

4. The method according to claim 1, the reaction pressure is 1 to 3 MPa during activation of the iron-based catalyst.

5. The method according to claim 1, the second step is carried out at a reaction temperature of 240 to 300 C., a reaction pressure of 1 to 3 MPa, and a space velocity of 2 to 20 NL/g.sub.(cat)/h.

6. The method according to claim 1, the synthesis gas is that H.sub.2/CO is adjusted to 0.7 to 2.5.

7. A method for producing an iron-based catalyst from a first precursor composed of ferrihydrite or a combination of ferrihydrite/goethite, wherein the an iron-based catalyst contains 10 to 100% of the number of iron atoms contained in the ferrihydrite and 0 to 90% of the number of iron atoms contained in the goethite with respect to 100% of the number of iron atoms contained in the first precursor.

8. The method for producing an iron-based catalyst according to claim 7, the method comprising the steps of: a) a step of selecting a precipitation time to obtain a desired fraction of the ferrihydrite and goethite in the first precursor prepared by the precipitation method; and b) a step of preparing a first precursor with a desired fraction of ferrihydrite and goethite under a precipitation time selected in the above step through a precipitation method.

9. The method for producing an iron-based catalyst according to claim 8, the method further comprising the steps of: c) a step of mixing the first precursor with silica; and d) a step of drying and calcining the first precursor mixed with the silica.

10. The method for producing an iron-based catalyst according to claim 8, the precipitation time selected is 20 minutes to 20 hours.

11. The method for producing an iron-based catalyst according to claim 8, the step b) is performed by mixing an aqueous solution of iron salt and an aqueous solution of a metal salt selected from the group consisting of copper, cobalt, manganese or a combination thereof, and then adding a basic aqueous solution to the mixed solution until the pH reaches 7 to 9 at a temperature of 75 to 85 C. for 20 minutes to 20 hours.

12. The method for producing an iron-based catalyst according to claim 9, a mass ratio of iron (Fe) to silica (SiO.sub.2) may be Fe:SiO.sub.2=100:11 to 27.

13. The method for producing an iron-based catalyst according to claim 9, the step c) is performed by adding silica or a silica precursor to the slurry containing the first precursor.

14. The method for producing an iron-based catalyst according to claim 13, the silica is fumed silica or colloidal silica, and the silica precursor is potassium silicate.

15. The method for producing an iron-based catalyst according to claim 9, the step d) is performed by drying the first precursor mixed with silica and calcining the first precursor mixed with silica in an atmospheric environment at 300 to 600 C. for 1 to 8 hours.

16. The method for producing an iron-based catalyst according to claim 15, the drying is performed by a spray drying method or a rotary evaporation method.

17. The method for producing an iron-based catalyst according to claim 7, the iron-based catalyst contains the number of iron atoms is 10 to 100% of a ferrihydrite phase fraction and the number of iron atoms is 0 to 90% of a hematite phase fraction with respect to 100% of the iron atoms.

18. An iron-based catalyst comprising: a partially hydrated iron hydroxide, wherein the number of iron atoms contained in the partially hydrated iron hydroxide is 10 to 100% with respect to 100% of the number of iron atoms contained in the iron-based catalyst, wherein a crystallite size of the partially hydrated iron hydroxide is 2 to 7 nm, and wherein the partially hydrated iron hydroxide is a super-magnetic substance.

19. The iron-based catalyst according to claim 18, the partially hydrated iron hydroxide is ferrihydrite.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0056] FIG. 1 is a graph showing the Mossbauer spectrum of each iron-based catalyst that derived the results of the phase fraction rates shown in Table 1.

[0057] FIG. 2 is a result of analysis of the phase fraction of the first precursor produced in Examples 1 to 12 and Comparative Examples 1 to 7 (Comparative Example 2 is not shown) by Mossbauer spectroscopy.

[0058] FIG. 3 shows the results of XRD analysis of (a) the first precursor of Example 13 and Comparative Example 8, (b) the catalyst of Example 13, and (c) the catalyst of Comparative Example 8.

[0059] FIG. 4 shows the results of observing the morphology of the catalyst of Example 13 in the high resolution (HR) mode of a transmission electron microscope (TEM) as a catalyst produced according to the present invention.

DETAILED DESCRIPTION OF EXAMPLE

[0060] Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

Example 1

[0061] A mixed solution is produced by mixing an aqueous solution of iron nitrate (Fe(NO.sub.3).sub.3.9H.sub.2O) at concentration of 2 mol and an aqueous solution of copper nitrate (Cu(NO.sub.3).sub.2.5H.sub.2O), and an aqueous solution of sodium carbonate (Na.sub.2CO.sub.3) at concentration of 2 mol was added to the mixed solution at a temperature of about 80 C. for about 80 minutes until the PH is reached to 8, and thereby, a first precursor composed of a phase fraction of ferrihydrite:goethite=77%:23% with reference to the number of iron atoms contained in each phase in the solid precipitate was obtained. The precipitate slurry containing the first precursor was filtered and washed with distilled water so that the remaining sodium was sufficiently removed, and a second precursor slurry was produced by adding fumed silica (SiO.sub.2) and an aqueous solution of potassium carbonate (K.sub.2CO.sub.3) to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate, and fumed silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:20 by mass ratio. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment of 400 C. for 8 hours, and thereby, an iron-based catalyst composed of a phase fraction ferrihydrite:hematite=82%:18% with reference to the number of iron atoms contained in each phase was obtained.

Example 2

[0062] The first precursor and the second precursor slurry were produced in the same manner as in Example 1, and then the second precursor slurry was dried through rotary evaporation (rotary vacuum evaporation), followed by calcining in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 3

[0063] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed using distilled water to sufficiently remove residual sodium, and a second precursor slurry was produced by adding fumed silica and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate and fumed silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:13 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 4

[0064] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed using distilled water to sufficiently remove residual sodium, and a second precursor slurry was produced by adding fumed silica and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate, and fumed silica were adjusted to be in the range of Fe:Cu:K:SiO.sub.2=100:5:5:25 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 5

[0065] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed with distilled water to sufficiently remove the residual sodium, and a second precursor slurry was produced by adding colloidal silica (SiO.sub.2) and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate, and colloidal silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:20 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 6

[0066] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed using distilled water to sufficiently remove residual sodium, and a second precursor slurry was produced by adding an aqueous solution of potassium silicate having a K:SiO.sub.2=5:20 by mass ratio to the washed precipitate slurry. A first precursor was produced in the same manner as in Example 1. The amounts of iron nitrate, copper nitrate, and potassium silicate were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:20 by mass ratio. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 7

[0067] A mixed solution is produced by mixing an aqueous solution of iron nitrate at concentration of 2 mol and an aqueous solution of copper nitrate, and an aqueous solution of sodium carbonate at concentration of 2 mol was added to the mixed solution at a temperature of about 80 C. for 5.3 hours to reach a pH of 8, and thereby, a first precursor composed of a phase fraction of ferrihydrite:goethite=19%:81% with reference to the number of iron atoms contained in each phase in the solid precipitate was obtained. A second precursor slurry was produced in the same manner as in Example 1 using the first precursor. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby, an iron-based catalyst composed of a phase fraction ferrihydrite:hematite=19%:81% with reference to the number of iron atoms contained in each phase was obtained.

Example 8

[0068] A mixed solution is produced by mixing an aqueous solution of iron nitrate at concentration of 2 mol and an aqueous solution of copper nitrate, and an aqueous solution of sodium carbonate at concentration of 2 mol was added to the mixed solution at a temperature of about 80 C. for about 20 minutes to reach a pH of 8, and thereby a first precursor containing only ferrihydrite as an iron-based compounds was obtained. The precipitate slurry containing the first precursor was filtered and washed using distilled water to sufficiently remove residual sodium, and a second precursor slurry was produced by adding fumed silica and and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate and fumed silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:13 by mass ratio. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric atmosphere at 400 C. for 8 hours, and thereby an iron-based catalyst containing only ferrihydrite as an iron-based compound was obtained.

Example 9

[0069] A first precursor and a second precursor slurry were produced in the same manner as in Example 1. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric atmosphere at 450 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 10

[0070] A first precursor and a second precursor slurry were produced in the same manner as in Example 1. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment at 300 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 11

[0071] A first precursor and a second precursor slurry were produced in the same manner as in Example 1. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment of 400 C. for 1 hour, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 12

[0072] A first precursor and a second precursor slurry were produced in the same manner as in Example 1. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment of 400 C. for 2 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Example 13

[0073] A first precursor was produced in the same manner as in Example 8. A second precursor slurry was produced in the same manner as in Example 1 using the first precursor. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst containing only ferrihydrite as an iron-based compound was obtained.

Example 14

[0074] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed using distilled water to sufficiently remove residual sodium, and a second precursor slurry was produced by adding fumed silica and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate, and fumed silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:4:16 by mass ratio. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Comparative Example 1

[0075] A mixed solution is produced by mixing an aqueous solution of iron nitrate at concentration of 2 mol and an aqueous solution of copper nitrate, and an aqueous solution of sodium carbonate at concentration of 2 mol was added to the mixed solution at a temperature of about 80 C. for 21.3 hours to reach a pH of 8, and thereby a first precursor containing only goethite as an iron-based compound was obtained. A second precursor slurry was produced in the same manner as in Example 1 using the first precursor. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst containing only hematite as an iron-based compound was obtained.

Comparative Example 2

[0076] A mixed solution is produced by mixing an aqueous solution of iron nitrate at concentration of 0.25 mol and an aqueous solution of copper nitrate, and an aqueous solution of sodium carbonate at concentration of 0.25 mol was added to the mixed solution at a temperature of about 80 C. for 42.7 hours to reach a pH of 8, and thereby a first precursor containing only goethite as an iron-based compound was obtained. A second precursor slurry was produced in the same manner as in Example 3 using the first precursor. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst containing only hematite as an iron-based compound was obtained.

Comparative Example 3

[0077] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed with distilled water so that the remaining sodium was sufficiently removed, and a second precursor slurry was produced by adding an aqueous solution of aluminum nitrate (Al(NO.sub.3).sub.3.9H.sub.2O) and an aqueous solution of potassium nitrate (KNO.sub.3) to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium nitrate, and aluminum nitrate were adjusted to be Fe:Cu:K:Al.sub.2O.sub.3=100:5:5:20 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric atmosphere at 400 C. for 8 hours, and thereby an iron-based catalyst containing only hematite as an iron-based compound was obtained.

Comparative Example 4

[0078] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed with distilled water so that the remaining sodium was sufficiently removed, and a second precursor slurry was produced by adding an aqueous solution of zirconium acetate (Zr.sup.x+.xCH.sub.3OOH) and an aqueous solution of potassium nitrate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium nitrate, and zirconium acetate were adjusted to be Fe:Cu:K:ZrO.sub.2=100:5:5:20 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric atmosphere at 400 C. for 8 hours, and thereby an iron-based catalyst containing only hematite as an iron-based compound was obtained.

Comparative Example 5

[0079] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed with distilled water so that the remaining sodium was sufficiently removed, and a second precursor slurry was produced by adding an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, and potassium carbonate were adjusted to be Fe:Cu:K=100:5:5 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric atmosphere at 400 C. for 8 hours, and thereby an iron-based catalyst containing only hematite as an iron-based compound was obtained.

Comparative Example 6

[0080] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed with distilled water so that the remaining sodium was sufficiently removed, and a second precursor slurry was produced by adding fumed silica and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate, and fumed silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:6 by mass ratio. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Comparative Example 7

[0081] A first precursor was produced in the same manner as in Example 1. The precipitate slurry containing the first precursor was filtered and washed with distilled water so that the remaining sodium was sufficiently removed, and a second precursor slurry was produced by adding fumed silica and an aqueous solution of potassium carbonate to the washed precipitate slurry. The amounts of iron nitrate, copper nitrate, potassium carbonate, and fumed silica were adjusted to be Fe:Cu:K:SiO.sub.2=100:5:5:31 by mass ratio. The second precursor slurry was dried by a spray drying method and then calcined in an atmospheric environment at 400 C. for 8 hours, and thereby an iron-based catalyst having the same phase fraction as in Example 1 was obtained.

Comparative Example 8

[0082] A first precursor was produced in the same manner as in Example 8. A second precursor slurry was produced in the same manner as in Comparative Example 5 using the first precursor. The second precursor slurry was dried by a rotary evaporation method and then calcined in an atmospheric atmosphere at 400 C. for 8 hours, and thereby an iron-based catalyst containing only hematite as an iron-based compound was obtained.

Experiment 1: Analysis of Properties of Catalysts as Produced

[0083] The phase fractions of the catalysts produced by the methods of Examples 1 to 14 and Comparative Examples 1 to 8 were analyzed by Mossbauer spectroscopy.

[0084] The results are illustrated in FIG. 1, and the phase fraction is calculated based on the results of the Mossbauer spectroscopy of FIG. 1, and thereby the typical results of the phase fractions of Examples 1, 7, and 8 and Comparative Example 1 are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Phase fraction (%) Ferrihydrite Hematite Example 1 82% 18% Example 7 19% 81% Example 8 100% 0% Comparative Example 1 0% 100%

[0085] The phase fractions of the catalysts produced by the methods of Examples 2 to 6, Examples 9 to 12, Example 14 and Comparative Examples 6 and 7 were the same as those of Example 1 at the level within the error range of 5%, and the catalyst produced by the method of Example 13 showed the same values as those of Example 8.

[0086] The phase fractions of the catalysts produced by the methods of Comparative Examples 2 to 5 and Comparative Example 8 were the same as those of Comparative Example 1.

[0087] From the above results, it is possible to confirm that the catalysts produced by the methods of Examples 1 to 13 are composed of a combination of ferrihydrite and hematite, and a phase fraction of ferrihydrite:hematite=10 to 100%:0 to 90% with respect to the number of iron atoms contained in each phase. On the contrary, it is possible to confirm that the Comparative Examples 1 to 5 and the Comparative Example 8 are composed of 100% of hematite, so that the phase fraction deviates from the above optimum value.

[0088] The phase fractions of the first precursors produced by the methods of Examples 1 to 14 and Comparative Examples 1 to 8 were analyzed by Mossbauer spectroscopy. As a result, the results are shown in FIG. 2, except for the results of Comparative Example 2. Based on the results of the Mossbauer spectroscopy of FIG. 2, the phase fractions are calculated and shown in Table 2 below.

TABLE-US-00002 TABLE 2 Phase fraction (%) Ferrihydrite Hematite Examples 1 to 6, Examples 9 to 12, Example 77% 23% 14, and Comparative Examples 3 to 7 Example 7 19% 81% Examples 8 and 13, and Comparative 100% 0% Example 8 Comparative Example 1 0% 100%

[0089] The phase fraction of the first precursor produced by the method of Comparative Example 2 was the same as that of Comparative Example 1.

[0090] When Examples 1 to 14 and Comparative Example 1 were compared in Table 1 and Table 2, in order to produce a catalyst composed of a phase fraction of ferrihydrite: hematite=10 to 100%:0 to 90% with respect to the number of iron atoms contained in each phase as in Examples 1 to 14, it is confirmed that the phase fraction should be ferrihydrite:goethite=10 to 100%:0 to 90% with respect to the number of iron atoms contained in each phase. When the first precursor is composed of goethite 100% as in Comparative Example 1, it can be confirmed that the phase fraction of the catalyst is 100% of the hematite which is out of the optimum value in Table 1. When Examples 1 to 14 and Comparative Examples 3 to 5 were compared in Table 1 and Table 2, in order to produce a catalyst composed of a phase fraction of ferrihydrite: hematite=10 to 100%:0 to 90% with respect to the number of iron atoms contained in each phase as in Examples 1 to 14, it can be confirmed that addition of SiO.sub.2 as a structural promoter is essential. It can be confirmed that the phase fraction of the catalyst is 100% of the hematite which is out of the optimum value in Table 1, when Al.sub.2O.sub.3 or ZrO.sub.2 is added as a structural promoter or when no structural promoter is added as in Comparative Examples 3 to 5 and Comparative Example 8.

Experiment 2: Fischer-Tropsch Synthesis Reaction without Catalytic Reduction Pretreatment and Catalytic Performance Analysis

[0091] The iron-based catalyst produced by the methods of Examples 1 to 12 and Comparative Examples 1 to 7 was placed in a laboratory-scale fixed bed reactor (amount of catalyst: 0.1 to 1.0 g), without performing a separate reduction pre-treatment on the catalyst, the Fischer-Tropsch synthesis reaction were performed under the conditions of H.sub.2/CO=1.0, GHSV=2.8 NL/g.sub.(cat)h, temperature=275 C., and pressure=1.5 MPa, and the results of evaluation on the performance of the catalyst are shown in Table 3.

TABLE-US-00003 TABLE 3 CO C5+ conversion CO.sub.2 Hydrocarbon distribution (wt %) Hydrocarbon rate selectivity C5+ productivity (%) (%) CH.sub.4 C2-C4 C5-C11 C12-C18 C19+ Total (g/g.sub.(cat)-h) Example 1 67.7 41.9 6.34 15.0 18.3 17.3 43.1 78.7 0.271 Example 2 67.1 41.5 5.56 16.2 18.7 17.2 42.4 78.2 0.268 Example 3 81.2 44.8 6.33 17.1 15.6 15.8 45.3 76.6 0.290 Example 4 58.8 36.0 3.43 9.46 15.2 16.9 55.0 87.1 0.309 Example 5 69.2 42.9 5.24 15.8 15.5 15.4 48.0 79.0 0.275 Example 6 77.4 44.6 5.30 15.5 11.0 12.8 55.5 79.2 0.288 Example 7 73.4 41.0 3.58 10.1 12.3 16.6 57.4 86.3 0.305 Example 8 78.9 46.4 5.96 15.8 15.3 15.6 47.3 78.2 0.296 Example 9 68.2 43.4 5.28 16.0 16.0 16.5 46.3 78.8 0.261 Example 10 64.0 44.1 5.55 16.5 17.4 16.4 44.1 78.0 0.260 Example 11 67.3 40.5 5.26 145.8 17.6 16.6 44.8 79.0 0.262 Example 12 68.1 41.1 5.23 15.5 17.9 16.5 44.9 79.3 0.274 Example 13 Example 14 75.3 43.4 5.86 17.1 17.3 16.4 43.4 77.1 0.284 Comparative 36.4 43.0 5.03 13.5 11.3 14.2 56.0 81.4 0.134 Example 1 Comparative 18.6 46.8 6.57 15.9 12.7 16.1 48.7 77.5 0.0729 Example 2 Comparative Example 3 Comparative 6.08 17.6 Example 4 Comparative 5.00 35.7 Example 5 Comparative 15.6 39.7 7.04 13.0 9.40 10.6 59.9 79.9 0.0719 Example 6 Comparative 30.0 30.3 5.84 13.3 18.1 18.2 44.6 80.9 0.137 Example 7 Comparative Example 8

[0092] From the above Table 3, it can be seen that the catalysts produced according to Examples 1 to 12 exhibit significantly higher CO conversion and C.sub.5+ hydrocarbon productivity than the catalysts produced according to Comparative Examples 1 to 7.

[0093] From the results of Comparative Examples 6 and 7 in Table 3, it can be confirmed that excellent catalytic performance cannot be obtained when the content of the structural promoter exceeds the optimum value of Fe:SiO.sub.2=100:11-27 by weight ratio.

[0094] The iron-based catalyst produced by the methods of Example 1 was placed in a laboratory-scale fixed bed reactor (amount of catalyst: 0.1 to 1.0 g), without performing a separate reduction pre-treatment on the catalyst, the Fischer-Tropsch synthesis reaction were performed under the conditions of H.sub.2/CO=2.0, GHSV=4.2 NL/g.sub.(cat)h, temperature=275 C., and pressure=1.5 MPa, and the results of evaluation on the performance of the catalyst are shown in Table 4.

TABLE-US-00004 TABLE 4 C5+ CO CO.sub.2 Hydrocarbon distribution (wt %) Hydrocarbon conversion selectivity C5+ productivity (%) (%) CH.sub.4 C2-C4 C5-C11 C12-C18 C19+ Total (g/g.sub.(cat)-h) Example 1 70.6 26.6 1.57 6.13 8.00 16.0 68.3 92.3 0.344

[0095] The iron-based catalyst produced by the methods of Examples 1 and 7 was placed in a laboratory-scale fixed bed reactor (amount of catalyst: 0.1 to 1.0 g), without performing a separate reduction pre-treatment on the catalyst, the Fischer-Tropsch synthesis reaction were performed under the conditions of H.sub.2/CO=1.0, GHSV=5.6 NL/g.sub.(cat)h, temperature=275 C., and pressure=3.0 MPa, and the results of evaluation on the performance of the catalyst are shown in Table 5.

TABLE-US-00005 TABLE 5 C5+ CO CO.sub.2 Hydrocarbon distribution (wt %) Hydrocarbon conversion selectivity C5+ productivity (%) (%) CH.sub.4 C2-C4 C5-C11 C12-C18 C19+ Total (g/g.sub.(cat)-h) Example 1 66.6 41.8 3.73 11.9 16.1 20.3 48.0 84.4 0.569 Example 7 74.2 41.1 3.96 12.41 16.1 20.5 47.0 83.6 0.619

[0096] The iron-based catalyst produced by the methods of Example 7 was placed in a laboratory-scale fixed bed reactor (amount of catalyst: 0.1 to 1.0 g), without performing a separate reduction pre-treatment on the catalyst, the Fischer-Tropsch synthesis reaction were performed under the conditions of H.sub.2/CO=1.0, GHSV=11.2 NL/g.sub.(cat)h, temperature=275 C., and pressure=3.0 MPa, and the results of evaluation on the performance of the catalyst are shown in Table 6.

TABLE-US-00006 TABLE 6 C5+ CO CO.sub.2 Hydrocarbon distribution (wt %) Hydrocarbon conversion selectivity C5+ productivity (%) (%) CH.sub.4 C2-C4 C5-C11 C12-C18 C19+ Total (g/g.sub.(cat)-h) Example 7 41.8 38.8 3.26 13.2 9.67 13.3 60.6 83.6 0.734

[0097] The iron-based catalyst produced by the methods of Example 14 was placed in a pilot-scale slurry bubble column reactor (amount of catalyst used: 20 to 200 kg), without performing a separate reduction pre-treatment on the catalyst, the Fischer-Tropsch synthesis reaction were performed under the conditions of CO.sub.2 content in the synthesis gas=11%, H.sub.2/CO=1.0, GHSV=10 NL/g.sub.(cat)h, temperature=275 C., and pressure=1.8 MPa, and the results of evaluation on the performance of the catalyst are shown in Table 7.

TABLE-US-00007 TABLE 7 Hydrocarbon C5+ CO CO.sub.2 distribution (wt %) Hydrocarbon conversion selectivity C2- productivity (%) (%) CH.sub.4 C4 C5+ (g/g.sub.(cat)-h) Example 14 79.7 34.2 6.08 12.5 81.4 0.713

[0098] The iron-based catalyst produced by the methods of Examples 1, and 3 to 6 was placed in a laboratory-scale fixed bed reactor (amount of catalyst: 0.1 to 1.0 g), and after a separate reduction pre-treatment was performed on the catalyst using a synthesis gas (H.sub.2+CO) under the conditions of H.sub.2/CO=1.0, GHSV=2.8 NL/g.sub.(cat)h, temperature=280 C., pressure=atmospheric pressure, and time=20 h, the results of evaluation on the performance of the catalyst are shown in Table 8.

TABLE-US-00008 TABLE 8 C5+ CO CO.sub.2 Hydrocarbon distribution (wt %) Hydrocarbon conversion selectivity C5+ productivity (%) (%) CH.sub.4 C2-C4 C5-C11 C12-C18 C19+ Total (g/g.sub.(cat)-h) Example 1 86.7 43.7 10.6 26.9 29.5 13.7 19.4 62.5 0.258 Example 3 83.9 46.2 7.77 21.3 20.4 15.6 34.9 71.0 0.264 Example 4 77.3 44.1 12.2 26.2 33.6 14.7 13.3 61.6 0.219 Example 5 87.7 43.2 9.76 24.4 25.3 15.5 25.1 65.9 0.263 Example 6 87.9 45.1 9.58 23.9 23.0 14.1 29.4 66.6 0.268

[0099] From the above Tables 3 to 8, it can be seen that when the Fischer-Tropsch synthesis reaction is carried out without performing a separate reduction pre-treatment on the iron-based catalysts produced by the methods of Examples 1 and 3 to 6, the CO conversion is slightly lower than that of the case wherein a separate reduction pre-treatment, however, it can be confirmed that the selectivity of C.sub.5+ hydrocarbons in the hydrocarbons can be significantly increased. As a result, the iron-based catalysts produced by the methods of Examples 1, 3 to 6 exhibited C.sub.5+ hydrocarbon productivity similar to or somewhat superior to those obtained by performing separate reduction pre-treatment even without performing separate reduction pre-treatment.

[0100] That is, as shown in the above Tables 3 to 8, when the Fischer-Tropsch synthesis reaction is carried out using the catalyst of the present invention, it is confirmed that, even without performing separate reduction pre-treatment, a more superior performance can be obtained than that of the case where a separate reduction pre-treatment is performed.

Experiment 3: Analysis of Catalytic Phase Change by Structural Promoter

[0101] In order to investigate the effect of the use of the structural promoter on the catalytic phase, the crystal structure of Example 13 which was a catalyst produced according to the present invention and the catalyst of Comparative Example 8 produced without using a structural promoter were analyzed by X-ray diffraction (XRD) using Rigaku DMAX-2500 that uses a Cu K light source. Further, XRD analysis was carried out on each of Example 13 and Comparative Example 8 prior to calcining (the first precursor) and after (catalyst).

[0102] The results are shown in FIG. 3.

[0103] FIG. 3 shows the results of (a) the first precursors of Example 13 and Comparative Example 8, (b) the catalyst of Example 13, and (c) the catalyst of Comparative Example 8.

[0104] FIG. 3 shows that the first precursor (a) of Comparative Example 8 exhibited a ferrihydrite pattern before calcining, but exhibited an XRD pattern almost identical to that of hematite as it was made into catalyst (c) after calcining. Through this, it can be seen that the thermal stability of the ferrihydrite phase is degraded so that it can be easily decomposed into hematite during calcining process.

[0105] However, as shown in FIG. 3(b), it can be seen that the ferrihydrite phase is retained in the case of Example 13 using silica as the structural promoter.

[0106] Further, the shape of the catalyst of Example 13 as a catalyst produced according to the present invention was observed in a high resolution (HRTEM) mode of a transmission electron microscope (TEM), and the results are shown in FIG. 4.

[0107] Through FIG. 4, it can be seen that the catalyst produced according to the present invention forms a small crystallite having a size on the order of several nanometers, specifically about 2 to 7 nm.