IRON-BASED CATALYST FOR FISCHER-TROPSCH SYNTHESIS, METHOD OF PREPARING THE SAME AND METHOD OF USING THE SAME

Abstract

A catalyst, including silica and iron. The silica is in the form of a mesoporous spherical particle. The iron is in the form of nanoparticles evenly distributed and encapsulated in the silica. The particle size of the silica is between 140 and 160 nm, and the silica includes pores between 2 and 9 nm in diameter.

Claims

1. A composition of matter, comprising silica and iron; wherein: the silica is in the form of a mesoporous spherical particle; the iron is in the form of nanoparticles evenly distributed and encapsulated in the silica; a particle size of the silica is between 140 and 160 nm; and the silica comprises pores between 2 and 9 nm in diameter.

2. The composition of matter of claim 1, wherein the iron accounts for 5-40 wt. % of the composition of matter, and the balance is the silica.

3. The composition of matter of claim 1, wherein the particle size of the silica is between 150 and 160 nm, and the pores of the silica are between 2.1 and 5.7 nm in diameter.

4. The composition of matter of claim 2, wherein the particle size of the silica is between 150 and 160 nm, and the pores of the silica are between 2.1 and 5.7 nm in diameter.

5. The composition of matter of claim 1, wherein the particle size of the silica is between 150 and 155 nm, and the pores of the silica are between 3.3 and 4.1 nm in diameter.

6. The composition of matter of claim 2, wherein the particle size of the silica is between 150 and 155 nm, and the pores of the silica are between 3.3 and 4.1 nm in diameter.

7. A method for preparing a composition of matter, the method comprising: 1) mixing ethanol and water with a volume ratio of 1-10:1-10 to yield an ethanol water, adding 0.005-0.02 g/mL of an organic amine to the ethanol water, to yield a mixture; 2) adding iron nanoparticles to the mixture obtained in 1), followed by addition of 0.05-0.2 g/mL of tetraethyl orthosilicate, to yield a product; 3) placing the product in a 1-15 megapascal CO.sub.2 atmosphere, heating to 35-45? C. for reaction, cooling, and releasing the CO.sub.2, to yield a solid product; and 4) washing the solid product obtained in 3) with water, drying, calcining, to yield a composition of matter.

8. The method of claim 7, wherein in 3), the product is placed in 6-9 megapascal CO.sub.2 atmosphere, heated to 40-45? C., and stirred for 22-26 hours.

9. The method of claim 7, wherein in 4), a calcining temperature is 500-560? C., and a calcining time is 4.5-5.5 hours.

10. The method of claim 8, wherein in 4), a calcining temperature is 500-560? C., and a calcining time is 4.5-5.5 hours.

11. The method of claim 7, wherein in 2), the iron nanoparticles account for 5-40 wt. % of the mixture.

12. The method of claim 8, wherein in 2), the iron nanoparticles account for 5-40 wt. % of the mixture.

13. A method of preparing an alpha-olefin, the method comprising introducing syngas and the composition of matter of claim 1 to a Fischer-Tropsch reactor, and subjecting them to reaction conditions as follows: reaction temperature 190-360? C., reaction pressure 0.5-5.0 megapascal, space velocity 400-20000 h.sup.?1 (V/V), stirring speed 400-1400 rpm, and H.sub.2/CO=1-3:1 (V/V).

14. The method of claim 13, further comprising reducing the composition of matter in the presence of pure hydrogen or syngas under the following conditions: reduction temperature 300-350? C., reduction pressure 0.2-1.2 megapascal, stirring speed 400-1400 rpm, space velocity 400-3500 h.sup.?1 (V/V), reaction time 6-18 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a SEM photo of an iron-based catalyst prepared without or with little CO.sub.2 pressure according to one embodiment of the disclosure;

[0027] FIG. 2 is a SEM photo of an iron-based catalyst according to one embodiment of the disclosure; and

[0028] FIG. 3 is a TEM photo of an iron-based catalyst according to one embodiment of the disclosure.

DETAILED DESCRIPTION

[0029] To further illustrate, embodiments detailing an iron-based catalyst for Fischer-Tropsch synthesis, preparation method and use thereof are described below. It should be noted that the following embodiments are intended to describe and not to limit the disclosure.

Example 1

[0030] 1.22 g of dodecylamine was added to a mixture of 10 mL of ethanol and 90 mL of water and stirred at room temperature for 1 h. Then 0.59 g of iron nanoparticles and 8.16 g of tetraethyl orthosilicate were added. The obtained mixture was transferred to a high-pressure reactor, CO.sub.2 injected, heated to 40? C. and stirred for 24 h. The CO.sub.2 pressure was 1.0 megapascal. Thereafter, the high-pressure reactor was cooled and the CO.sub.2 released. The resulting solid was washed with water and suction filtered for several times, dried overnight, to yield a powder. The powder was calcined in a muffle furnace at 500? C. for 5 h, tableted, and sieved to yield a monodisperse iron-based catalyst comprising 20 wt. % of iron (20 wt % Fe@SiO.sub.2CO.sub.2-1). With the increase of carbon dioxide, the catalyst is transformed from a disc-shaped lamination (shown in FIG. 1) to homogeneous spherical particles (shown in FIG. 2). The iron nanoparticles are encapsulated in the mesoporous spherical silica and distributed evenly. The particle size of the carrier silica is 150 nm, and the mesoporous diameter of the carrier silica is 2.5?0.4 nm (as shown in FIG. 3).

[0031] 1.5 mL of 60-80 meshes of the prepared iron-based catalyst was added to a pressurized fixed-bed reactor (?10?500 mm) and reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 800 h.sup.?1 (V/V), and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 260? C., pressure 1.0 megapascal, space velocity 400 h.sup.?1 (V/V), H.sub.2/CO=3/1 (V/V). The reaction results are shown in Table 2.

[0032] 15 mL of more than 140 meshes of the prepared iron-based catalyst was added to a 1-L stirred slurry reactor, followed by addition of 500 mL of liquid wax. The resulting mixture was reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 600 h.sup.?1 (V/V), stirring speed 600 rpm, and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 260? C., pressure 1.0 megapascal, space velocity 700 h.sup.?1 (V/V), stirring speed 600 rpm, and H.sub.2/CO=3/1 (V/V). The reaction results are shown in Table 2.

Example 2

[0033] 0.5 g of formamide was added to a mixture of 90 mL of ethanol and 10 mL of water and stirred at room temperature for 1 h. Then 0.34 g of iron nanoparticles and 5 g of tetraethyl orthosilicate were added. The obtained mixture was transferred to a high-pressure reactor, CO.sub.2 injected, heated to 45? C. and stirred for 22 h. The CO.sub.2 pressure was 4.0 megapascal. Thereafter, the high-pressure reactor was cooled and the CO.sub.2 released. The resulting solid was washed with water and suction filtered for several times, dried overnight, to yield a powder. The powder was calcined in a muffle furnace at 560? C. for 4.5 h, tableted, and sieved to yield a monodisperse iron-based catalyst comprising 20 wt. % of iron (20 wt % Fe@SiO.sub.2CO.sub.2-4). The particle size of the carrier silica is 155 nm, and the mesoporous diameter of the carrier silica is 3.7?0.4 nm.

[0034] 1.5 mL of 60-80 meshes of the prepared iron-based catalyst was added to a pressurized fixed-bed reactor (?10?500 mm) and reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 300? C., pressure 1.2 megapascal, space velocity 3000 h.sup.?1 (V/V), and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 260? C., pressure 5.0 megapascal, space velocity 400 h.sup.?1 (V/V), H.sub.2/CO=2/1 (V/V). The reaction results are shown in Table 2.

[0035] 15 mL of more than 140 meshes of the prepared iron-based catalyst was added to a 1-L stirred slurry reactor, followed by addition of 500 mL of liquid wax. The resulting mixture was reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 300? C., pressure 1 megapascal, space velocity 600 h.sup.?1 (V/V), stirring speed 600 rpm, and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 260? C., pressure 1.0 megapascal, space velocity 700 h.sup.?1 (V/V), stirring speed 600 rpm, and H.sub.2/CO=2/1 (V/V). The reaction results are shown in Table 2.

Example 3

[0036] 2 g of piperazine was added to a mixture of 10 mL of ethanol and 90 mL of water and stirred at room temperature for 1 h. Then 1.45 g of iron nanoparticles and 20 g of tetraethyl orthosilicate were added. The obtained mixture was transferred to a high-pressure reactor, CO.sub.2 injected, heated to 35? C. and stirred for 26 h. The CO.sub.2 pressure was 6.0 megapascal. Thereafter, the high-pressure reactor was cooled, and the CO.sub.2 released. The resulting solid was washed with water and suction filtered for several times, dried overnight, to yield a powder. The powder was calcined in a muffle furnace at 540? C. for 5.5 h, tableted, and sieved to yield a monodisperse iron-based catalyst comprising 20 wt. % of iron (20 wt % Fe@SiO.sub.2CO.sub.2-6). The particle size of the carrier silica is 160 nm, and the mesoporous diameter of the carrier silica is 4.6?0.4 nm.

[0037] 1.5 mL of 60-80 meshes of the prepared iron-based catalyst was added to a pressurized fixed-bed reactor (?10?500 mm) and reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 500? C., pressure 0.2 megapascal, space velocity 800 h.sup.?1 (V/V), and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 230? C., pressure 1.0 megapascal, space velocity 2000 h.sup.?1 (V/V), H.sub.2/CO=1/1 (V/V). The reaction results are shown in Table 2.

[0038] 15 mL of more than 140 meshes of the prepared iron-based catalyst was added to a 1-L stirred slurry reactor, followed by addition of 500 mL of liquid wax. The resulting mixture was reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 600 h.sup.?1 (V/V), stirring speed 600 rpm, and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 240? C., pressure 1.0 megapascal, space velocity 3000 h.sup.?1 (V/V), stirring speed 600 rpm, and H.sub.2/CO=1/1 (V/V). The reaction results are shown in Table 2.

Example 4

[0039] 1.5 g of aniline was added to a mixture of 10 mL of ethanol and 90 mL of water and stirred at room temperature for 1 h. Then 0.69 g of iron nanoparticles and 10 g of tetraethyl orthosilicate were added. The obtained mixture was transferred to a high-pressure reactor, CO.sub.2 injected, heated to 40? C. and stirred for 24 h. The CO.sub.2 pressure was 9.0 megapascal. Thereafter, the high-pressure reactor was cooled and the CO.sub.2 released. The resulting solid was washed with water and suction filtered for several times, dried overnight, to yield a powder. The powder was calcined in a muffle furnace at 500? C. for 5 h, tableted, and sieved to yield a monodisperse iron-based catalyst comprising 20 wt. % of iron (20 wt % Fe@SiO.sub.2CO.sub.2-9). The particle size of the carrier silica is 155 nm, and the mesoporous diameter of the carrier silica is 5.3?0.4 nm.

[0040] 1.5 mL of 60-80 meshes of the prepared iron-based catalyst was added to a pressurized fixed-bed reactor (?10?500 mm) and reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 800 h.sup.?1 (V/V), and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 240? C., pressure 1.0 megapascal, space velocity 800 h.sup.?1 (V/V), H.sub.2/CO=3/1 (V/V). The reaction results are shown in Table 2.

[0041] 15 mL of more than 140 meshes of the prepared iron-based catalyst was added to a 1-L stirred slurry reactor, followed by addition of 500 mL of liquid wax. The resulting mixture was reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 600 h.sup.?1 (V/V), stirring speed 600 rpm, and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 260? C., pressure 1.0 megapascal, space velocity 7000 h.sup.?1 (V/V), stirring speed 600 rpm, and H.sub.2/CO=3/1 (V/V). The reaction results are shown in Table 2.

Example 5

[0042] 0.61 g of laurylamine was added to a mixture of 10 mL of ethanol and 90 mL of water and stirred at room temperature for 1 h. Then 0.59 g of iron nanoparticles and 8.16 g of tetraethyl orthosilicate were added. The obtained mixture was transferred to a high-pressure reactor, CO.sub.2 injected, heated to 40? C. and stirred for 24 h. The CO.sub.2 pressure was 4.0 megapascal. Thereafter, the high-pressure reactor was cooled and the CO.sub.2 released. The resulting solid was washed with water and suction filtered for several times, dried overnight, to yield a powder. The powder was calcined in a muffle furnace at 500? C. for 5 h, tableted, and sieved to yield a monodisperse iron-based catalyst comprising 20 wt. % of iron (20 wt % Fe@SiO.sub.2CO.sub.2-4). The particle size of the carrier silica is 145 nm, and the mesoporous diameter of the carrier silica is 3.7?0.4 nm.

[0043] 1.5 mL of 60-80 meshes of the prepared iron-based catalyst was added to a pressurized fixed-bed reactor (?10?500 mm) and reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 800 h.sup.?1 (V/V), and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 260? C., pressure 1.0 megapascal, space velocity 12000 h.sup.?1 (V/V), H.sub.2/CO=3/1 (V/V). The reaction results are shown in Table 2.

[0044] 15 mL of more than 140 meshes of the prepared iron-based catalyst was added to a 1-L stirred slurry reactor, followed by addition of 500 mL of liquid wax. The resulting mixture was reduced in pure hydrogen by temperature programmed reduction. The reduction conditions were as follows: reduction temperature 400? C., pressure 0.4 megapascal, space velocity 600 h.sup.?1 (V/V), stirring speed 600 rpm, and time 12 h. After reduction, the synthesis gas was introduced to the reactor and the reaction conditions were as follows: temperature 230? C., pressure 1.0 megapascal, space velocity 1000 h.sup.?1 (V/V), stirring speed 600 rpm, and H.sub.2/CO=3/1 (V/V). The reaction results are shown in Table 2.

Examples 6-10

[0045] Examples 6-10 are basically the same as that in Example 5 except the iron content of the iron-based catalyst, the CO.sub.2 pressure, the reaction temperature, and the space velocity. The iron content of the iron-based catalyst and the CO.sub.2 pressure are listed in Table 1. The reaction temperature, the space velocity, and the reaction results are shown in Table 2.

[0046] The iron content of the iron-based catalyst and the CO.sub.2 pressure in the synthesis process in Examples 1-10 are listed in Table 1. In addition to the listed component, the rest is silica.

TABLE-US-00001 TABLE 1 Iron content of iron-based catalysts and CO.sub.2 pressure in the synthesis process in Examples 1-10 Example Fe content (wt. %) CO.sub.2 pressure (MPa) Example 1 20% 1 Example 2 20% 4 Example 3 20% 6 Example 4 20% 9 Example 5 20% 4 Example 6 10% 4 Example 7 10% 1 Example 8 30% 4 Example 9 30% 1 Example 10 40% 4

TABLE-US-00002 TABLE 2 Reactivity of iron-based catalysts of Examples 1-10 in olefin synthesis reaction Iron-based CO C.sub.1 C.sub.5+ Olefin catalysts Reaction conditions Conversion % Selectivity % Selectivity % content % Example 1 260? C., 400 h.sup.?1 fixed-bed 33.4 15.7 47.8 46.1 reactor 260? C., 700 h.sup.?1 slurry 38.4 15.8 46.5 35.9 reactor Example 2 260? C., 400 h.sup.?1 fixed-bed 51.2 4.8 78.0 64.4 reactor 260? C., 700 h.sup.?1 slurry 40.8 5.2 77.6 65.1 reactor Example 3 230? C., 2000 h.sup.?1 fixed-bed 41.3 6.1 75.2 61.6 reactor 240? C., 3000 h.sup.?1 slurry 32.9 5.8 76.2 63.5 reactor Example 4 240? C., 800 h.sup.?1 fixed-bed 65.9 9.5 73.8 57.2 reactor 260? C., 7000 h.sup.?1 slurry 19.0 9.7 75.9 72.0 reactor Example 5 260? C., 12000 h.sup.?1 fixed-bed 26.1 4.9 78.5 62.4 reactor 230? C., 1000 h.sup.?1 slurry 51.7 4.7 77.3 61.1 reactor Example 6 240? C., 6000 h.sup.?1 fixed-bed 28.1 7.6 75.2 63.9 reactor 250? C., 3000 h.sup.?1 slurry 42.6 7.1 79.4 63.2 reactor Example 7 240? C., 6000 h.sup.?1 fixed-bed 28.0 5.7 80.0 61.4 reactor 250? C., 3000 h.sup.?1 slurry 42.8 4.5 81.7 63.1 reactor Example 8 240? C., 2000 h.sup.?1 fixed-bed 51.2 11.3 73.6 62.7 reactor Example 9 330? C., 4000 h.sup.?1 slurry 30.3 6.8 51.9 70.3 reactor Example 10 270? C., 4000 h.sup.?1 slurry 42.1 6.9 78.3 63.6 reactor

[0047] It will be obvious to those skilled in the art that changes and modifications may be made, and therefore, the aim in the appended claims is to cover all such changes and modifications.