KR20140013293A - Manufacturing method of actived magnetite - Google Patents
Manufacturing method of actived magnetite Download PDFInfo
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- KR20140013293A KR20140013293A KR1020120079917A KR20120079917A KR20140013293A KR 20140013293 A KR20140013293 A KR 20140013293A KR 1020120079917 A KR1020120079917 A KR 1020120079917A KR 20120079917 A KR20120079917 A KR 20120079917A KR 20140013293 A KR20140013293 A KR 20140013293A
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- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- 238000000034 method Methods 0.000 claims abstract description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 61
- WKPSFPXMYGFAQW-UHFFFAOYSA-N iron;hydrate Chemical compound O.[Fe] WKPSFPXMYGFAQW-UHFFFAOYSA-N 0.000 claims description 30
- 238000010438 heat treatment Methods 0.000 claims description 29
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 28
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 28
- 238000006243 chemical reaction Methods 0.000 claims description 23
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 19
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 9
- 239000011790 ferrous sulphate Substances 0.000 claims description 9
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 9
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 8
- 235000006408 oxalic acid Nutrition 0.000 claims description 6
- 230000002194 synthesizing effect Effects 0.000 claims description 5
- 229910021529 ammonia Inorganic materials 0.000 claims description 4
- VBIXEXWLHSRNKB-UHFFFAOYSA-N ammonium oxalate Chemical compound [NH4+].[NH4+].[O-]C(=O)C([O-])=O VBIXEXWLHSRNKB-UHFFFAOYSA-N 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 235000014413 iron hydroxide Nutrition 0.000 claims description 2
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims description 2
- 230000001376 precipitating effect Effects 0.000 claims 1
- 238000001556 precipitation Methods 0.000 abstract description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 26
- 239000002245 particle Substances 0.000 description 15
- 229910002092 carbon dioxide Inorganic materials 0.000 description 13
- 239000001569 carbon dioxide Substances 0.000 description 13
- 230000008859 change Effects 0.000 description 9
- 239000013078 crystal Substances 0.000 description 9
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 7
- 206010021143 Hypoxia Diseases 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 229910000462 iron(III) oxide hydroxide Inorganic materials 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 238000003786 synthesis reaction Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229940062993 ferrous oxalate Drugs 0.000 description 4
- OWZIYWAUNZMLRT-UHFFFAOYSA-L iron(2+);oxalate Chemical compound [Fe+2].[O-]C(=O)C([O-])=O OWZIYWAUNZMLRT-UHFFFAOYSA-L 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000010792 warming Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- VEPSWGHMGZQCIN-UHFFFAOYSA-H ferric oxalate Chemical compound [Fe+3].[Fe+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O VEPSWGHMGZQCIN-UHFFFAOYSA-H 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052743 krypton Inorganic materials 0.000 description 1
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229910052704 radon Inorganic materials 0.000 description 1
- SYUHGPGVQRZVTB-UHFFFAOYSA-N radon atom Chemical compound [Rn] SYUHGPGVQRZVTB-UHFFFAOYSA-N 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/02—Oxides; Hydroxides
- C01G49/08—Ferroso-ferric oxide [Fe3O4]
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Compounds Of Iron (AREA)
Abstract
The present invention relates to a method for preparing an active magnet by heat-treating ferric hydrate (FeC 2 O 4 .2H 2 O) synthesized by precipitation and to an active magnetite prepared by the method. This invention can produce active magnetite safely and economically.
Description
The present invention relates to a method for producing active magnetite used to decompose and recycle carbon dioxide, which is the main culprit of global warming.
Carbon dioxide (CO 2 ) generated from the exhaust of fossil fuels is one of the main causes of global warming by acting as a greenhouse glass. Therefore, studies to decompose carbon dioxide and recycle it to solve the global warming problem are continuously conducted.
Carbon dioxide is processed through a process of capture, transport and storage, and among them, there are a wet method and a dry method using a chemical adsorption principle. The wet method adsorbs carbon dioxide using liquid materials such as ammonia and amines, and the dry method adsorbs carbon dioxide using solid particles such as CaO, MgO, and ZnO.
On the other hand, the active magnetite (Fe 3 O 4 -δ ) studied by Y. Tamaura in 1992 not only decomposes CO 2 but also reacts with C and H 2 adsorbed on the surface of Fe 3 O 4 -δ by CH 4. Has the advantage of recycling the CO 2 as an energy source has been actively researched worldwide.
Activated magnetite (Fe 3 O 4 -δ ) is prepared by the hydrogen reduction reaction of the magnetite (Fe 3 O 4 ), there is a technology related to this there is Korea Patent Publication No. 2008-0057084. However, the method of producing active magnetite (Fe 3 O 4 -δ ) by reducing magnetite (Fe 3 O 4 ) with hydrogen is dangerous because it uses highly explosive hydrogen, and the manufacturing process is complicated and expensive. There is a problem. Therefore, there is a need for a technology capable of producing active magnetite (Fe 3 O 4 -δ ) safely and economically.
An object of the present invention is to provide a method for producing active magnetite capable of producing active magnetite (Fe 3 O 4-δ ) and to the active magnetite prepared by the production method in order to solve the above problems safely and economically. .
In order to achieve the above object, the present invention comprises the steps of: a) synthesizing iron hydrate (FeC 2 O 4 · 2H 2 O); And b) heat-treating the ferric acid salt synthesized in step a) in the presence of an inert medium.
At this time, the iron hydrate of step a) is synthesized by the reaction of ferrous sulfate (FeSO 4 · 7H 2 O) and a precipitant, the precipitant is ammonium oxalate ((NH 4 ) 2 C 2 O 4 · H 2 O) , Oxalic acid (H 2 C 2 O 4 ) and a mixture of oxalic acid (H 2 C 2 O 4 ) and ammonia (NH 4 OH).
In addition, the step b), the step of heat-treating the iron hydrate to produce magnetite (Fe 3 O 4 ) and carbon monoxide (CO); And reducing the magnetite by the carbon monoxide.
On the other hand, the present invention provides an active magnetite prepared by the above method.
In the present invention, active magnetite can be prepared safely and economically because the active magnetite is prepared by a simple process of pyrolyzing ferrous hydrate (FeC 2 O 4 .2H 2 O) in the presence of an inert medium.
1 is a graph analyzing the crystal phase of iron hydrate according to an embodiment of the present invention.
2 is a photograph confirming the granulation of the iron hydrate according to an embodiment of the present invention.
3 is a TG / DTA result of the iron oxalate for explaining an embodiment of the present invention.
4 is a photograph confirming the shape of the active magnetite according to an embodiment of the present invention.
5 is an XRD measurement result of the result synthesized according to the heat treatment temperature for explaining an embodiment of the present invention.
6 is a specific surface area measurement result of the result synthesized according to the heat treatment temperature for explaining an embodiment of the present invention.
7 is an XRD measurement result of the magnetite synthesized according to the heat treatment temperature for explaining an embodiment of the present invention.
FIG. 8 is a TG / DTA measurement result of active magnetite prepared under heat treatment conditions at 450 ° C. for 3 hours to explain an embodiment of the present invention.
Hereinafter, the present invention will be described.
The present invention relates to a method for preparing active magnetite by synthesizing iron hydrate by precipitation and heat treatment thereof, and to an active magnetite prepared by the above method.
1.Method of Preparing Active Magnetite
One) Ferrous acid synthesis
First, iron hydrate (FeC 2 O 4 .2H 2 O), which is a raw material for obtaining active magnetite (Fe 3 O 4 -δ ), is synthesized. Here, the method for synthesizing the iron hydrate is not particularly limited, but it is preferable to use the precipitation method. This is because the precipitation process is not only simple in the synthesis of iron hydrate, but also the synthesis of iron hydrate with various particle sizes and particle size distribution depending on the synthesis conditions. In particular, when using the precipitation method can be synthesized iron oxalate having a small particle size, such a small particle size of the oxalate can have a large surface area and wide activity.
As a method of synthesizing the iron hydrate by the precipitation method, it is possible to add a precipitant to ferrous sulfate (FeSO 4 · 7H 2 O) to react. At this time, the precipitation agent used is not particularly limited, ammonium oxalate ((NH 4) 2 C 2 O 4 · H 2 O), oxalic acid (H 2 C 2 O 4) and oxalic acid (H 2 C 2 O 4) and It is preferred to select from the group consisting of a mixture of ammonia (NH 4 OH). The ferrous sulfate can be obtained inexpensively as being discharged as a by-product during titania production. Therefore, the present invention manufactures the active magnetite as a final product using ferrous sulfate, which is an inexpensive material, and as a result, the production cost of the active magnetite can be lowered.
On the other hand, the equivalent ratio of ferrous sulfate and the precipitant is preferably 1: 1 to 1: 2.5, more preferably 1: 1. This is because when the ferrous sulfate and the precipitant are reacted at the equivalent ratio, ferrous oxalate having a small particle size is synthesized, and consequently, the specific surface area of the ferrous hydrate can be widened. In addition, it is preferable to use the concentration of ferrous sulfate and a precipitant at 0.1 to 1 M, respectively. In addition, the agitation speed is 50 to 500rpm, the reaction temperature is 25 to 60 ℃, the reaction time is 20 to 60 minutes to facilitate the precipitation reaction.
Thereafter, the precipitate produced by the precipitation reaction of ferrous sulfate (FeSO 4 · 7H 2 O) is filtered and washed, and then dried for a predetermined time to obtain a synthesized iron hydrate. The obtained iron hydrate is in a powder state in which particles having various sizes and shapes (primary cubic particles are formed first and then irregularly hexahedral particles are formed through agglomeration) are collected, and the size (diameter) of the particles is not particularly limited. It is preferable to exist in the range of 10-50 micrometers.
2) Ferrous acid Heat treatment
Heat treatment of the synthesized ferrous acid salt produces active magnetite. Heat treatment of ferrous oxalate produces magnetite (Fe 3 O 4 ), carbon dioxide (CO 2 ) and carbon monoxide (CO), and the active magnetite is produced by reducing the magnetite by the produced carbon monoxide. .
When the ferric acid salt is heat-treated, crystal water decomposition reaction occurs as in the following Reaction Formula (1), and when the heat treatment temperature is increased, magnetite (Fe 3 O 4 ), carbon dioxide (CO 2 ), and carbon monoxide (CO) are generated as shown in the following Reaction Formula (2). do.
FeC 2 O 4 · 2H 2 O → FeC 2 O 4 + 2H 2 O-Q (1)
3FeC 2 O 4 → Fe 3 O 4 + 2CO 2 + 4CO + 139.50kJ (2)
Subsequently, when the partial pressure of carbon monoxide (CO) sufficient to reduce the magnetite (Fe 3 O 4 ) is reached in the course of the decomposition reaction in Scheme (2), active magnetite is produced by the reduction reaction as in Scheme (3) below. do.
Fe 3 O 4 + ΔCO → Fe 3 O 4 -δ + δCO 2 - 283.05kJ (3)
Here, the heat treatment of ferrous salts is carried out in the presence of an inert medium to prevent oxidation of the resulting magnetite and active magnetite. . At this time, the usable inert medium is not particularly limited, but the group consisting of nitrogen (N 2 ), argon (Ar), helium (He), krypton (Kr), neon (Ne), xenon (Xe), and radon (Rn). It is preferably selected from, and considering the economics, it is more preferable to use nitrogen or argon.
On the other hand, the temperature and time for heat-treating the iron hydrate is not particularly limited, but the heat treatment temperature is preferably 300 ~ 500 ℃, the active magnetite is mainly produced, the heat treatment time is preferably 1 to 5 hours.
As described above, the present invention is a method of manufacturing an active magnetite by reducing the magnetite to hydrogen, since the iron hydroxide is heat-treated at a relatively low temperature in the presence of an inert medium to decompose the magnetite and carbon monoxide, and then the magnetite is reduced to carbon monoxide to prepare the active magnetite. Compared to the safe preparation of the active magnetite. In addition, active magnetite having various oxygen deficiency (δ values) may be manufactured by adjusting the heat treatment temperature and time. As such, the active magnetite having various oxygen deficiency (δ value) shows better activity than the magnetite. In particular, the active magnetite having a larger oxygen deficiency (δ value) has higher activity, and thus the decomposition performance of carbon dioxide is improved.
2. Activated magnetite and its utilization
The present invention provides an active magnetite prepared by the above production method. The active magnetite (Fe 3 O 4 −δ ) of the present invention may have various oxygen deficiency degrees (δ values), but the δ value representing the oxygen deficiency is greater than 0 and less than 1 (0 <δ <1) Is preferred, and more preferably greater than 0.1171 and less than 0.6583 (0.1171 <δ <0.6583).
Such active magnetite of the present invention can be utilized in various industrial fields, in particular, it can be usefully used for the decomposition and recycling of carbon dioxide (CO 2 ). That is, the present invention may provide a method of forming methane (CH 4 ) by decomposing carbon dioxide into activated magnetite prepared by the above-described manufacturing method. Specifically, the active magnetite of the present invention vitrifies (decomposes) carbon dioxide into carbon (C) or carbon monoxide (CO) and the vitrified carbon is adsorbed onto the surface of the active magnetite particles, wherein the activated magnetite on which carbon is adsorbed is hydrogen ( Reaction with H 2 ) forms methane (CH 4 ). As such, the active magnetite of the present invention converts carbon dioxide into methane gas so that it can be recycled as an energy source.
Hereinafter, the present invention will be described in detail by examples. However, these examples are intended to illustrate the present invention in detail, and the scope of the present invention is not limited to these examples.
[Example 1]
1) Ferrous Oxide Synthesis
FeSO 4 · 7H 2 O (Purity 98% ~ 102%, Samchun Pure Chemical Co., Ltd., Korea) and (NH 4) 2 C 2 O 4 · H 2 O ( purity of 99%, Junsei Chemical Co., Ltd , Japan) solution concentration of 0.25M and equivalence ratio of 1: 1 neutralization precipitation was carried out. Neutralization precipitation was carried out by dropwise addition of (NH 4 ) 2 C 2 O 4 · H 2 O to FeSO 4 · 7H 2 O. The stirring speed was 300 rpm, the reaction temperature was 25 ° C., and the reaction time was 30 minutes. It was. The precipitate produced by the reaction was filtered, washed three times with distilled water, and dried at 70 ° C. for 24 hours to synthesize iron hydrate in powder form.
2) Active Magnetite Manufacturing
After the ferric acid salt synthesized above was added to the reactor, heat treatment was performed at 600 ° C. at intervals of 100 ° C. to prepare active magnetite. At this time, nitrogen gas was injected into the inert medium at 50 sccm, and the heat treatment time was 1 hour for each temperature.
Experimental Example 1
The crystal phase of the iron hydrate synthesized in Example 1 was analyzed by XRD (PANanalytical Co, X pert PRD PW3040, Cu Kα 40kV, 40mA), and the granularity was observed by SEM (Hitachi, S-4800). 1 and 2 are shown.
Referring to Figure 1, it can be seen that the iron hydrate synthesized in Example 1 is the same diffraction angle with α-FeC 2 O 4 · 2H 2 O (PDF # 23-0293). On the other hand, the diffraction intensity is inconsistent, which seems to be caused by the difference between the growth plane and the growth direction of ferrous oxalate crystals.
Looking at Figure 2, it can be seen that the shape having an irregular hexahedral shape, which is consistent with the trigonal system, which is the crystal structure of the iron hydrate, it can be seen that the iron hydrate was well synthesized. On the other hand, as a result of confirming the particle size of the synthesized iron hydrate powder was in the range of 10.30 ~ 45.88㎛, the average particle size was 21.39㎛.
[Experimental Example 2]
Pyrolysis characteristics according to the heat treatment temperature of the ferric acid salt synthesized in Example 1 were analyzed by TG / DTA (Material Analysis & Characterization, TG / DTA 2000S), and the results are shown in FIG. 3.
Referring to FIG. 3, a small amount of mass decreases in a temperature section below 100 ° C., which may be due to the evaporation of moisture adsorbed on the surface and the inside of the iron hydrate particles. In the temperature range of 135 ℃ ~ 250 ℃ it can be seen that the endothermic reaction by the crystallization of the water according to the reaction formula (1).
On the other hand, in the temperature range of 338 ℃ 412 ℃ it can be seen that the reaction of the reaction formula (2) and (3) proceeds. Specifically, it can be seen that FeC 2 O 4 is pyrolyzed in the temperature range of 338 ° C. to 405 ° C. as in Scheme (2) to generate Fe 3 O 4 and exothermic reactions that release CO and CO 2 . When the CO partial pressure sufficient to reduce Fe 3 O 4 is reached in the course of the decomposition reaction in Scheme (2), the reduction reaction (endothermic reaction) as in Scheme (3) is performed in the temperature range of 345 ° C to 405 ° C. It can be seen that Fe 3 O 4 -δ is generated as it occurs.
In this way, Fe 3 O 4 -δ can be confirmed by the mass change of the iron hydrate . In other words, the mass loss rate from the mass at 100 ° C., at which the water adsorbed on the ferric acid salt evaporates completely, to 400 ° C. without mass change was found to be 58.02%, and such mass loss was FeC 2 O 4 · 2H 2. When O was decomposed and changed to Fe 3 O 4 , the theoretical mass reduction was greater than 57.10%. This difference in mass loss rate can be seen to be due to the production of Fe 3 O 4 -δ .
On the other hand, the iron hydrate was heat-treated at 400 ℃ for 1 hour and observed by the SEM (Hitachi, S-4800) as a result, it was confirmed that the Fe 3 O 4 -δ was generated as shown in FIG. This supports that Fe 3 O 4 -δ is generated within the range of 345 ° C to 405 ° C.
[Experimental Example 3]
The crystal phase according to the heat treatment temperature of the iron hydrate synthesized in Example 1 was analyzed by XRD (PANanalytical Co, X pert PRD PW3040, Cu Kα 40kV, 40mA), the results are shown in FIG.
Referring to FIG. 5, anhydrous FeC 2 O 4 was formed by crystallization of the water in the reaction formula (1) at 200 ° C. and 300 ° C., Fe 3 O 4 was produced at 400 ° C., and a small amount of α − at 500 ° C. It can be confirmed that Fe is produced. The α-Fe phase could not be confirmed under calcination heat treatment conditions at 600 ° C. It can be seen that the crystal phase change according to the heat treatment temperature is consistent with the TG / DTA result of analyzing the pyrolysis property.
[Experimental Example 4]
The specific surface area change (Micromertics Co, ASAP 2400) according to the heat treatment temperature of the ferrous hydrate synthesized in Example 1 was measured, and the results are shown in FIG. 6.
Referring to Figure 6, the specific surface area of the iron hydrate before the heat treatment was 10.14m 2 / g, after the heat treatment at 100 ℃ increased to 29.56m 2 / g. This can be seen as the evaporation of moisture present in the particles and on the surface.
On the other hand, the specific surface area of the specimen heat-treated at 200 ° C increased rapidly to 175.07m 2 / g, because the crystal water (2H 2 O) was removed by the decomposition of ferrous oxalate.
Thereafter, the specific surface area slightly decreased to 169.58m 2 / g at 300 ° C, and after the heat treatment at 400 ° C, the specific surface area rapidly decreased to 15.43m 2 / g, and the specific surface area gradually decreased as the heat treatment temperature increased. I could confirm that. This may be due to the change in density that occurs when the pores coalesce and FeC 2 O 4 phase changes to Fe 3 O 4 .
[Example 2]
The active magnetite was prepared in the same manner as in Example 1 except that the heat treatment temperatures of the ferric acid salt were 400 ° C., 450 ° C. and 500 ° C., and the heat treatment was performed for 3 hours at each temperature.
Experimental Example 5
The crystal phase according to the heat treatment temperature of the iron hydrate synthesized in Example 2 was analyzed by XRD (PANanalytical Co, X pert PRD PW3040, Cu Kα 40kV, 40mA), the results are shown in FIG.
Referring to Figure 7, Fe 3 O 4 in the specimen heat-treated at 400 ℃ 3 hours In addition, it was confirmed that a small amount of Fe 3 C was produced. The formation of such Fe 3 C can be seen to be due to the following reaction formula (4) and formula (5).
3FeC 2 O 4 + 2CO → Fe 3 C + 7CO 2 (4)
Fe 3 O 4 + 6CO → Fe 3 C + 5CO 2 (5)
In the specimen heat-treated at 450 ° C. for 3 hours, Fe 3 C was not found and only Fe 3 O 4 was confirmed. This is because CO and CO 2 are released and Fe 3 O 4 is generated by oxidation of Fe 3 C due to the temperature rise.
Fe 3 O 4 was applied to specimens heat-treated at 500 ° C for 3 hours. In addition, small amounts of α-Fe and Fe 4 N were observed. This is mainly due to the reduction of Fe 3 O 4 to α-Fe, Fe 4 N is produced as the nitriding reaction of α-Fe proceeds when the atomic percentage of N 2 relative to the secondary α-Fe produced 20% Because
On the other hand, Fe 3 O 4 produced at each temperature is reduced to Fe 3 O 4 -δ , because only Fe 3 O 4 is produced at 450 ℃ Fe 3 O 4 -δ can be seen to be the most produced at 450 ℃ have.
[ Experimental Example 6]
Oxygen deficiency δ value of Fe 3 O 4 -δ according to the heat treatment temperature of the iron hydrate synthesized in Example 2 was measured by the following method.
Referring to Figure 8, in the temperature range of 100 ~ 320 ℃ Fe 3 O 4 is oxidized to Fe 2 O 3 The mass increase appears, Fe 3 O 4 -δ in the temperature range after 320 ℃ Fe 3 O 4 Mass increase as oxidized to Fe 2 O 3 through. Based on this, it was confirmed that the specimens were mixed with Fe 3 O 4 and Fe 3 O 4 -δ , and the mass increase in the temperature range after 320 ° C. except for the increase in mass caused by the oxidation reaction of Fe 3 O 4 was observed. It was judged that it was preferable to calculate the value of δ on the basis of the above, and the value of δ was calculated as follows.
Fe 3 O 4 -δ produced by the reduction of Fe 3 O 4 is oxidized to Fe 3 O 4 by the reaction of formula (6) when heat-treated in an oxidizing atmosphere, and when oxidation proceeds further, the reaction of formula (7) Is oxidized to Fe 2 O 3 . The first two reactions proceed in series, and the sum of the two equations is equal to equation (8).
2Fe 3 O 4 -δ + δO 2 → 2Fe 3 O 4 (6)
2Fe 3 O 4 + (1/2) O 2 → 3Fe 2 O 3 (7)
2Fe 3 O 4 -δ + δO 2 + (1/2) O 2 → 3Fe 2 O 3 (8)
Based on the theoretical chemical reaction, the weight change when the Fe 3 O 4 -δ was oxidized in the oxidation atmosphere was measured by TGA, and the oxygen deficiency δ value was calculated by Equation (9) below.
Specifically, in Example 2, the sample heat-treated at 450 ° C. for 3 hours was heat-treated again to 600 ° C. and oxidized to Fe 2 O 3 , and the weight change was measured by TGA. The results are shown in FIG. 8.
In Equation (9), the molecular weight (3Fe 2 O 3 mass-2Fe 3 O 4 -δ mass) is 1.3891 mg as a weight change when 2Fe 3 O 4 -δ is oxidized to 3Fe 2 O 3 , which is generated. 3Fe 2 O 3 was 17.95428 mg (see FIG. 8). Meanwhile, when oxidized 26.132mg of 3Fe 2 O 3 is converted into mole, 5.454 x 10 -5 mole
By the same method as described above, the mass change and δ value of the specimen heat-treated for 3 hours at 400 ℃ and 500 ℃ of Example 2 is as shown in Table 1.
Referring to Table 1, the cause of the low δ value at 400 ℃ is due to the production of Fe 3 C, the low δ value even at 500 ℃ can be seen to be due to the production of α-Fe and Fe 4 N. (See FIG. 7).
Claims (5)
b) a method of producing an active magnetite comprising the step of heat-treating the iron hydrate synthesized in step a) in the presence of an inert medium.
The iron hydroxide of step a) is synthesized by the reaction of ferrous sulfate (FeSO 4 · 7H 2 O) with a precipitant,
The precipitating agent is a mixture of ammonium oxalate ((NH 4) 2 C 2 O 4 · H 2 O), oxalic acid (H 2 C 2 O 4) and oxalic acid (H 2 C 2 O 4) and ammonia (NH 4 OH) Method for producing an active magnetite, characterized in that selected from the group consisting of.
The step b)
b-1) heat-treating the iron hydrate to produce magnetite (Fe 3 O 4 ) and carbon monoxide (CO); And
b-2) the method of producing an active magnetite, characterized in that the step of reducing the magnetite by the carbon monoxide.
The heat treatment temperature of step b) is 300 ~ 500 ℃ method for producing an active magnetite, characterized in that.
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| CN104646062A (en) * | 2015-02-12 | 2015-05-27 | 浙江理工大学 | Preparation method for bamboo pulp cellulose-based integrated Fenton catalyst Fe<3+>C2O4/R |
| WO2022234833A1 (en) * | 2021-05-07 | 2022-11-10 | オードメルス株式会社 | Carbon dioxide processing agent and method for producing same |
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| CN104646062A (en) * | 2015-02-12 | 2015-05-27 | 浙江理工大学 | Preparation method for bamboo pulp cellulose-based integrated Fenton catalyst Fe<3+>C2O4/R |
| WO2022234833A1 (en) * | 2021-05-07 | 2022-11-10 | オードメルス株式会社 | Carbon dioxide processing agent and method for producing same |
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