Iron-based catalyst, method for preparing the same, and method for producing alpha-olefins using the same

Abstract

A catalyst including between 50.0 and 99.8 percent by weight of iron, between 0 and 5.0 percent by weight of a first additive, between 0 and 10 percent by weight of a second additive, and a carrier. The first additive is ruthenium, platinum, copper, cobalt, zinc, or a metal oxide thereof. The second additive is lanthanum oxide, cerium oxide, magnesium oxide, aluminum oxide, silicon dioxide, potassium oxide, manganese oxide, or zirconium oxide.

Claims

1. A method for preparing a catalyst, the method comprising: 1) mixing anhydrous ferric nitrate, a nitrate of a first additive, and amorphous silicon dioxide with n-octanol to form a first solution, wherein a total weight percentage of the anhydrous ferric nitrate, the nitrate of the first additive, and the amorphous silicon dioxide in the first solution is between 3 wt. % and 20 wt. %; stirring and heating the first solution to a temperature of between 140 and 180? C. for 4 hrs to yield a heated first solution; cooling and filtering the heated first solution to yield a first product; drying the first product to yield a black solid; grinding the black solid for 20 to 40 mins to yield a ground black solid, then roasting the ground black solid for 5 hrs at between 400 and 600? C. to yield a catalyst precursor; and 2) dissolving a precursor of a second additive in water or ethyl alcohol to form a second solution; performing dry impregnation by adding the second solution to the catalyst precursor to yield an impregnated catalyst precursor; conducting an aging treatment of the impregnated catalyst precursor for between 12 and 24 hrs to form a second product; drying the second product at a temperature of between 100 and 130? C. to yield a dried second product, and roasting the dried second product for 4 to 10 hrs at a temperature of between 300 and 1200? C. to yield a roasted second product; and tableting and sieving the roasted second product to yield the catalyst; wherein: the catalyst comprises, by a total weight of the catalyst, between 50.0 and 99.8 percent by weight of iron, between 0 and 5.0 percent by weight of the first additive, between 0 and 10 percent by weight of the second additive, and a carrier; the first additive is ruthenium, platinum, copper, cobalt, or zinc, or the first additive is a metal oxide selected from oxides of ruthenium, platinum, copper, cobalt, and zinc; the second additive is lanthanum oxide, cerium oxide, magnesium oxide, aluminum oxide, potassium oxide, manganese oxide, or zirconium oxide; and the carrier is silicon dioxide.

2. The method of claim 1, wherein the catalyst comprises between 1 and 40 percent by weight of the carrier, between 1 and 2 percent by weight of the first additive, between 2 and 6 percent by weight of the second additive, and the rest is the iron.

3. The method of claim 1, wherein total weight percentage of the anhydrous ferric nitrate, the nitrate of the first additive, and the amorphous silicon dioxide in the first solution is between 5 wt. % and 15 wt. %.

4. The method of claim 2, wherein total weight percentage of the anhydrous ferric nitrate, the nitrate of the first additive, and the amorphous silicon dioxide in the first solution is between 5 wt. % and 15 wt. %.

5. The method of claim 1, wherein a particle size of the catalyst precursor is between 50 and 60 nm; and the catalyst precursor is spherical and monodispersed.

6. The method of claim 2, wherein a particle size of the catalyst precursor is between 50 and 60 nm; and the catalyst precursor is spherical and monodispersed.

7. The method of claim 3, wherein a particle size of the catalyst precursor is between 50 and 60 nm; and the catalyst precursor is spherical and monodispersed.

8. The method of claim 7, wherein a particle size of the catalyst precursor is between 50 and 60 nm; and the catalyst precursor is spherical and monodispersed.

9. The method of claim 1, wherein in 2), the precursor of the second additive is K.sub.2CO.sub.3, Zr(NO.sub.3).sub.4, or Al(NO.sub.3).sub.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described hereinbelow with reference to accompanying drawings, in which the sole FIGURE is a transmission electron microscopy (TEM) photo of an iron-based catalyst prepared using a thermal decomposition method of an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) For further illustrating the invention, experiments detailing a catalyst, a method for preparing the catalyst, and a method for producing alpha-olefin using the catalyst are described below. It should be noted that the following examples are intended to describe and not to limit the invention.

Example 1

(3) 60 g of anhydrous ferric nitrate and 10 g of amorphous silicon dioxide were mixed with 800 mL of n-octanol to form a mixed solution. The mixed solution was stirred so that the nitrate was dissolved, and the mixed solution was heated to 140? C. The temperature was maintained for 4 hrs. The mixed solution was cooled and filtrated to yield a first product. The first product was dried to yield a black solid. The black solid was grinded using a planetary mill, then the black solid was roasted in a muffle furnace for 5 hrs at 400? C. to yield a catalyst precursor. 0.55 g of La(NO.sub.3).sub.3 was dissolved in water to form 18 mL of a second additive solution. The catalyst precursor was soaked in the second additive solution and was aged for 12 hrs to form a second product. The second product was dried at 100? C., and was roasted for 10 hrs at 800? C. The second product was compressed to be tablets and sieved to yield the catalyst 53% Fe1% La.sub.2O.sub.3/SiO.sub.2 comprising 53 percent by weight of iron, 1 percent by weight of La.sub.2O.sub.3, and the rest was silicon dioxide.

(4) 1.5 mL of the catalyst having the particle sizes of between 60 and 80 meshes was added in a pressurized fixed bed reactor (?10?500 mm), in which the catalyst was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 400? C., 0.2 Megapascal, 400 h.sup.?1 (V/V), and 18 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 230? C., 2.5 Megapascal, 2000 h.sup.?1 (V/V), and H.sub.2/CO=2/1. The result of the reaction is shown in Table 2.

(5) 15 mL of the catalyst having the particle size being above 140 meshes was added in a slurry agitator with a volume of 1 L, then 500 mL of liquid paraffin was added in the slurry agitator to form a third mixture. The third mixture was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 300? C., 0.2 Megapascal, 400 h.sup.?1 (V/V), 400 rpm, and 18 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 240? C., 0.5 Megapascal, 3000 h.sup.?1 (V/V), 400 rpm, and H.sub.2/CO=2/1. The result of the reaction is shown in Table 2.

Example 2

(6) 80 g of anhydrous ferric nitrate and 5 g of amorphous silicon dioxide were mixed with 800 mL of n-octanol to form a mixed solution. The mixed solution was stirred so that the nitrate was dissolved, and the mixed solution was heated to 140? C. The temperature was maintained for 4 hrs. The mixed solution was cooled and filtrated to yield a first product. The first product was dried to yield a black solid. The black solid was grinded using a planetary mill, then the black solid was roasted in a muffle furnace for 5 hrs at 400? C. to yield a catalyst precursor. 0.55 g of K.sub.2CO.sub.3 was dissolved in water to form 18 mL of a second additive solution. The catalyst precursor was soaked in the second additive solution and was aged for 12 hrs to form a second product. The second product was dried at 100? C., and was roasted for 10 hrs at 400? C. The second product was compressed to be tablets and sieved to yield the iron-based catalyst 75% Fe.sub.2% K.sub.2O1% MnO/SiO.sub.2 comprising 75 percent by weight of iron, 2 percent by weight of K.sub.2O, 1 percent by weight of MnO, and the rest was silicon dioxide.

(7) 1.5 mL of the catalyst having the particle sizes of between 60 and 80 meshes was added in a pressurized fixed bed reactor (?10?500 mm), in which the catalyst was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 400? C., 0.4 Megapascal, 800 h.sup.?1 (V/V), and 12 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 200? C., 1.0 Megapascal, 1500 h.sup.?1 (V/V), and H.sub.2/CO=3/1. The result of the reaction is shown in Table 2.

(8) 15 mL of the catalyst having the particle size being above 140 meshes was added in a slurry agitator with a volume of 1 L, then 500 mL of liquid paraffin was added in the slurry agitator to form a third mixture. The third mixture was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 400? C., 0.4 Megapascal, 600 h.sup.?1 (V/V), 600 rpm, and 12 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 200? C., 1.0 Megapascal, 2000 h.sup.?1 (V/V), 600 rpm, and H.sub.2/CO=3/1. The result of the reaction is shown in Table 2.

Example 3

(9) 60 g of anhydrous ferric nitrate, 10 g of cobalt nitrate, and 5 g of amorphous silicon dioxide were mixed with 800 mL of n-octanol to form a mixed solution. The mixed solution was stirred so that the nitrate was dissolved, and the mixed solution was heated to 140? C. The temperature was maintained for 4 hrs. The mixed solution was cooled and filtrated to yield a first product. The first product was dried to yield a black solid. The black solid was grinded using a planetary mill, then the black solid was roasted in a muffle furnace for 5 hrs at 400? C. to yield a catalyst precursor. 1.5 g of Cu(NO.sub.3).sub.2 was dissolved in water to form 18 mL of a second additive solution. The catalyst precursor was soaked in the second additive solution and was aged for 12 hrs to form a second product. The second product was dried at 100? C., and was roasted for 10 hrs at 400? C. The second product was compressed to be tablets and sieved to yield the iron-based catalyst 60% Fe10% Co2% CuO/SiO.sub.2 comprising 60 percent by weight of iron, 10 percent by weight of Co, 2 percent by weight of CuO, and the rest was silicon dioxide.

(10) 15 mL of the catalyst having the particle size being above 140 meshes was added in a slurry agitator with a volume of 1 L, then 500 mL of liquid paraffin was added in the slurry agitator to form a third mixture. The third mixture was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 400? C., 0.8 Megapascal, 600 h.sup.?1 (V/V), 1000 rpm, and 10 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 220? C., 2.0 Megapascal, 2000 h.sup.?1 (V/V), 1000 rpm, and H.sub.2/CO=1/1. The result of the reaction is shown in Table 2.

Example 4

(11) 60 g of anhydrous ferric nitrate, 4 g of cobalt nitrate, and 5 g of amorphous silicon dioxide were mixed with 800 mL of n-octanol to form a mixed solution. The mixed solution was stirred so that the nitrate was dissolved, and the mixed solution was heated to 140? C. The temperature was maintained for 4 hrs. The mixed solution was cooled and filtrated to yield a first product. The first product was dried to yield a black solid. The black solid was grinded using a planetary mill, then the black solid was roasted in a muffle furnace for 5 hrs at 400? C. to yield a catalyst precursor. 3 g of Zr(NO.sub.3).sub.4 was dissolved in water to form 18 mL of a second additive solution. The catalyst precursor was soaked in the second additive solution and was aged for 12 hrs to form a second product. The second product was dried at 100? C., and was roasted for 10 hrs at 600? C. The second product was compressed to be tablets and sieved to yield the iron-based catalyst 54% Fe5% Co4% ZrO.sub.2/SiO.sub.2 comprising 54 percent by weight of iron, 5 percent by weight of Co, 4 percent by weight of ZrO.sub.2, and the rest was silicon dioxide.

(12) 1.5 mL of the catalyst having the particle sizes of between 60 and 80 meshes was added in a pressurized fixed bed reactor (?10?500 mm), in which the catalyst was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 400? C., 1.2 Megapascal, 1000 h.sup.?1 (V/V), and 10 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 240? C., 3.0 Megapascal, 800 h.sup.?1 (V/V), and H.sub.2/CO=2/1. The result of the reaction is shown in Table 2.

(13) 15 mL of the catalyst having the particle size being above 140 meshes was added in a slurry agitator with a volume of 1 L, then 500 mL of liquid paraffin was added in the slurry agitator to form a third mixture. The third mixture was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 400? C., 0.4 Megapascal, 600 h.sup.?1 (V/V), 600 rpm, and 12 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 200? C., 1.0 Megapascal, 2000 h.sup.?1 (V/V), 600 rpm, and H.sub.2/CO=3/1. The result of the reaction is shown in Table 2.

Example 5

(14) 80 g of anhydrous ferric nitrate, and 1 g of amorphous silicon dioxide were mixed with 800 mL of n-octanol to form a mixed solution. The mixed solution was stirred so that the nitrate was dissolved, and the mixed solution was heated to 140? C. The temperature was maintained for 4 hrs. The mixed solution was cooled and filtrated to yield a first product. The first product was dried to yield a black solid. The black solid was grinded using a planetary mill, then the black solid was roasted in a muffle furnace for 5 hrs at 400? C. to yield a catalyst precursor. 5 g of Al(NO.sub.3).sub.3 was dissolved in water to form 18 mL of a second additive solution. The catalyst precursor was soaked in the second additive solution and was aged for 12 hrs to form a second product. The second product was dried at 100? C., and was roasted for 10 hrs at 800? C. The second product was compressed to be tablets and sieved to yield the iron-based catalyst 90% Fe4% Al.sub.2O.sub.3/SiO.sub.2 comprising 90 percent by weight of iron, 4 percent by weight of Al.sub.2O.sub.3, and the rest was silicon dioxide.

(15) 1.5 mL of the catalyst having the particle sizes of between 60 and 80 meshes was added in a pressurized fixed bed reactor (?10?500 mm), in which the catalyst was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 500? C., 1.2 Megapascal, 1500 h.sup.?1 (V/V), and 6 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 260? C., 5.0 Megapascal, 400 h.sup.?1 (V/V), and H.sub.2/CO=2/1. The result of the reaction is shown in Table 2.

(16) 15 mL of the catalyst having the particle size being above 140 meshes was added in a slurry agitator with a volume of 1 L, then 500 mL of liquid paraffin was added in the slurry agitator to form a third mixture. The third mixture was heated at a programmed temperature and was reduced under pure hydrogen atmosphere. The reducing condition was: 500? C., 1.2 Megapascal, 1500 h.sup.?1 (V/V), 1400 rpm, and 6 hrs. Following the reduction, the reactor was cooled, and the syngas was introduced to perform a syngas reaction. The syngas reaction condition was: 260? C., 4.0 Megapascal, 700 h.sup.?1 (V/V), 1400 rpm, and H.sub.2/CO=2/1. The result of the reaction is shown in Table 2.

Examples 6-10

(17) The examples follow a basic method in the Example 5, except that the content and the additive are different. The contents of the components in the examples are shown in Table 1. The content of the silicon dioxide equals to the total content of components minus the contents of the three components in Table 1.

(18) TABLE-US-00001 TABLE 1 Contents of components in the examples Content of Content of the first the second Number Content of iron additive additive Example 1 53% Fe 1% La.sub.2O.sub.3 Example 2 75% Fe 2% K.sub.2O 1% MnO Example 3 60% Fe 10% Co 2% CuO Example 4 54% Fe 5% Co 4% ZrO.sub.2 Example 5 90% Fe 6% Al.sub.2O.sub.3 Example 6 80% Fe 3% Cr.sub.2O.sub.3 0.5% K.sub.2O Example 7 95% Fe 1% ZnO 0.2% K.sub.2O Example 8 70% Fe 2% CeO.sub.2 0.3% CuO Example 9 68% Fe 2% TiO.sub.2 0.1% Ru Example 10 98% Fe 1% Al.sub.2O.sub.3 0.2% K.sub.2O

(19) TABLE-US-00002 TABLE 2 Performance of iron-based catalyst in olefin synthesis reaction CO C.sub.1 C.sub.5.sup.+ conver- selec- selec- Olefin sion tivity tivity content Catalyst Reaction Condition rate % % % % Example 1 230? C., 2000 h.sup.?1, 42.5 6.2 75.1 61.2 fixed bed 240? C., 3000 h.sup.?1, 33.6 5.5 76.6 63.8 slurry bed Example 2 250? C., 1500 h.sup.?1, 51.2 4.8 78.0 64.4 fixed bed 260? C., 2000 h.sup.?1, 40.8 5.2 77.6 65.1 slurry bed Example 3 240? C., 10000 h.sup.?1, 12.1 14.8 58.4 45.7 fixed bed 220? C., 2000 h.sup.?1, 35.9 12.4 61.3 40.6 slurry bed Example 4 240? C., 800 h.sup.?1, 66.7 9.1 74.0 58.3 fixed bed 260? C., 7000 h.sup.?1, 19.6 9.4 76.4 72.1 slurry bed Example 5 260? C., 400 h.sup.?1, 33.4 15.7 47.8 46.1 fixed bed 260? C., 700 h.sup.?1, 38.4 15.8 46.5 35.9 slurry bed Example 6 260? C., 12000 h.sup.?1, 26.3 4.7 81.1 64.2 fixed bed 230? C., 1000 h.sup.?1, 52.5 4.5 81.4 63.9 slurry bed Example 7 240? C., 6000 h.sup.?1, 28.5 6.7 78.8 65.4 fixed bed 250? C., 3000 h.sup.?1, 43.3 6.1 79.5 65.9 slurry bed Example 8 280? C., 4000 h.sup.?1, 71.2 5.2 81.3 61.4 fixed bed 220? C., 1000 h.sup.?1, 10.5 4.1 83.8 62.7 slurry bed Example 9 240? C., 2000 h.sup.?1, 52.6 11.2 74.4 63.6 fixed bed Example 10 300? C., 4000 h.sup.?1, 30.1 6.5 52.0 70.0 slurry bed

(20) As shown in FIG. 1, when the contents and the preparation method in the invention are satisfied, monodispersed particles having uniform particle size of 70 nm are prepared. According to the examples, when the contents of the components are not coincident with the method in the invention, for example, the Example 3 and Example 5 have low olefin content; when the contents of the components are coincident with the method in the invention, the example has high olefin content. Within the preferable range of contents, the catalyst features higher alpha-olefin selectivity.

(21) Unless otherwise indicated, the numerical ranges involved in the invention include the end values. While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.