CN112569982B - Precipitated epsilon/epsilon iron carbide-containing composition, preparation method thereof, catalyst and application thereof, and Fischer-Tropsch synthesis method - Google Patents
Precipitated epsilon/epsilon iron carbide-containing composition, preparation method thereof, catalyst and application thereof, and Fischer-Tropsch synthesis method Download PDFInfo
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- 239000000203 mixture Substances 0.000 title claims abstract description 117
- 239000003054 catalyst Substances 0.000 title claims abstract description 71
- 238000002360 preparation method Methods 0.000 title claims abstract description 47
- 229910000704 hexaferrum Inorganic materials 0.000 title claims description 10
- 238000001308 synthesis method Methods 0.000 title abstract description 4
- 229910001567 cementite Inorganic materials 0.000 claims abstract description 321
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 109
- 239000012535 impurity Substances 0.000 claims abstract description 66
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 46
- 229910052742 iron Inorganic materials 0.000 claims abstract description 30
- 239000007789 gas Substances 0.000 claims description 162
- 239000002243 precursor Substances 0.000 claims description 113
- 238000002156 mixing Methods 0.000 claims description 75
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 68
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 52
- 238000000034 method Methods 0.000 claims description 47
- 239000000463 material Substances 0.000 claims description 46
- 238000001035 drying Methods 0.000 claims description 41
- 239000002244 precipitate Substances 0.000 claims description 35
- 238000005406 washing Methods 0.000 claims description 32
- 238000006243 chemical reaction Methods 0.000 claims description 31
- 230000015572 biosynthetic process Effects 0.000 claims description 25
- 229910052799 carbon Inorganic materials 0.000 claims description 18
- 230000008569 process Effects 0.000 claims description 13
- 230000009467 reduction Effects 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 150000002505 iron Chemical class 0.000 claims description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 7
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 6
- 230000000630 rising effect Effects 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 5
- 150000003839 salts Chemical class 0.000 claims description 5
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 238000000975 co-precipitation Methods 0.000 claims description 4
- 239000000446 fuel Substances 0.000 claims description 4
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 4
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 claims description 3
- FRHBOQMZUOWXQL-UHFFFAOYSA-L ammonium ferric citrate Chemical compound [NH4+].[Fe+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O FRHBOQMZUOWXQL-UHFFFAOYSA-L 0.000 claims description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 3
- 229960004642 ferric ammonium citrate Drugs 0.000 claims description 3
- IMBKASBLAKCLEM-UHFFFAOYSA-L ferrous ammonium sulfate (anhydrous) Chemical compound [NH4+].[NH4+].[Fe+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O IMBKASBLAKCLEM-UHFFFAOYSA-L 0.000 claims description 3
- 239000004313 iron ammonium citrate Substances 0.000 claims description 3
- 235000000011 iron ammonium citrate Nutrition 0.000 claims description 3
- 235000014413 iron hydroxide Nutrition 0.000 claims description 3
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims description 3
- 239000011736 potassium bicarbonate Substances 0.000 claims description 3
- 235000015497 potassium bicarbonate Nutrition 0.000 claims description 3
- 229910000028 potassium bicarbonate Inorganic materials 0.000 claims description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 3
- 235000017550 sodium carbonate Nutrition 0.000 claims description 3
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 3
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims description 2
- 159000000014 iron salts Chemical class 0.000 claims description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 2
- 235000011181 potassium carbonates Nutrition 0.000 claims description 2
- 235000011118 potassium hydroxide Nutrition 0.000 claims description 2
- 238000002203 pretreatment Methods 0.000 claims description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 294
- 229910002092 carbon dioxide Inorganic materials 0.000 description 147
- 239000001569 carbon dioxide Substances 0.000 description 147
- 239000000047 product Substances 0.000 description 42
- 239000012065 filter cake Substances 0.000 description 34
- 239000002002 slurry Substances 0.000 description 34
- 239000000243 solution Substances 0.000 description 32
- 238000010438 heat treatment Methods 0.000 description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 29
- 238000003763 carbonization Methods 0.000 description 28
- 238000001816 cooling Methods 0.000 description 28
- 239000008367 deionised water Substances 0.000 description 28
- 229910021641 deionized water Inorganic materials 0.000 description 28
- 238000001914 filtration Methods 0.000 description 28
- 238000001228 spectrum Methods 0.000 description 26
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 21
- 239000001099 ammonium carbonate Substances 0.000 description 21
- 235000012501 ammonium carbonate Nutrition 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 12
- 239000013078 crystal Substances 0.000 description 7
- 238000011065 in-situ storage Methods 0.000 description 7
- 238000004611 spectroscopical analysis Methods 0.000 description 7
- 239000006227 byproduct Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- OAVRWNUUOUXDFH-UHFFFAOYSA-H 2-hydroxypropane-1,2,3-tricarboxylate;manganese(2+) Chemical compound [Mn+2].[Mn+2].[Mn+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O OAVRWNUUOUXDFH-UHFFFAOYSA-H 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- -1 iron carbides Chemical class 0.000 description 4
- 239000011564 manganese citrate Substances 0.000 description 4
- 235000014872 manganese citrate Nutrition 0.000 description 4
- 229940097206 manganese citrate Drugs 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 239000012752 auxiliary agent Substances 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 239000003245 coal Substances 0.000 description 3
- 238000000151 deposition Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 238000005234 chemical deposition Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
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- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000005984 hydrogenation reaction Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000002671 adjuvant Substances 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
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- 238000004587 chromatography analysis Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
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- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000007130 inorganic reaction Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000006053 organic reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 229920000151 polyglycol Polymers 0.000 description 1
- 239000010695 polyglycol Substances 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
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
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/20—Carbon compounds
- B01J27/22—Carbides
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/613—10-100 m2/g
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/615—100-500 m2/g
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/03—Precipitation; Co-precipitation
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/03—Precipitation; Co-precipitation
- B01J37/031—Precipitation
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/16—Reducing
- B01J37/18—Reducing with gases containing free hydrogen
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2/00—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon
- C10G2/30—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen
- C10G2/32—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen with the use of catalysts
- C10G2/33—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen with the use of catalysts characterised by the catalyst used
- C10G2/331—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen with the use of catalysts characterised by the catalyst used containing group VIII-metals
- C10G2/332—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen with the use of catalysts characterised by the catalyst used containing group VIII-metals of the iron-group
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- General Chemical & Material Sciences (AREA)
- Catalysts (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention relates to the field of Fischer-Tropsch synthesis reaction, and discloses a composition containing precipitated epsilon/epsilon' iron carbide, a preparation method thereof, a catalyst and application thereof, and a Fischer-Tropsch synthesis method. A precipitated epsilon/epsilon ' iron carbide-containing composition comprising, based on the total amount of the composition, 95 to 100 mole% of precipitated epsilon/epsilon ' iron carbide and 0 to 5 mole% of Fe-containing impurities, said Fe-containing impurities being iron-containing species other than epsilon/epsilon ' iron carbide; wherein the specific surface area of the composition is 20-260m 2 And/g. The epsilon/epsilon' iron carbide can be simply prepared, and is used as an active component to obtain continuous and stable Fischer-Tropsch synthesis reaction, and the effective product has high selectivity.
Description
Technical Field
The invention relates to the field of Fischer-Tropsch synthesis reaction, in particular to a composition containing precipitated epsilon/epsilon' iron carbide, a preparation method, a catalyst and application thereof, and a Fischer-Tropsch synthesis method.
Background
The primary energy structure of China is characterized by rich coal, oil deficiency and less gas. With the development of the economy in China, the dependence of petroleum on the outside is continuously increased.
Fischer-Tropsch synthesis is an increasingly important energy conversion pathway in recent years, which can convert carbon monoxide and H 2 Is converted into liquid fuel and chemicals.
The reaction equation for Fischer-Tropsch synthesis is as follows:
(2n+1)H 2 +nCO→C n H 2n+2 +nH 2 O (1)，
2nH 2 +nCO→C n H 2n +nH 2 O (2)。
in addition to alkanes and alkenes, industrial Fischer-Tropsch synthesis can also produce carbon dioxide (CO) 2 ) And methane (CH) 4 ). The Fischer-Tropsch synthesis reaction is complicated in mechanism and numerous in steps, such as CO dissociation, carbon (C) hydrogenation, CH x Chain growth, and hydrogenation and dehydrogenation reactions that result in desorption and oxygen (O) removal of hydrocarbon products.
Iron is the cheapest transition metal for making fischer-tropsch catalysts. Conventional iron-based catalysts have a very high water gas shift (co+h) 2 O→CO 2 +H 2 ) The activity is high, so that the traditional iron-based catalyst usually has higher byproduct CO 2 The selectivity is typically 25% -45% of the carbon monoxide of the conversion feedstock. This is one of the major disadvantages of iron-based catalysts for fischer-tropsch synthesis reactions.
The change of the active phase of the iron-based catalyst is very complex, which results in considerable controversy over the nature of the active phase and the fischer-tropsch reaction mechanism of the iron-based catalyst.
CN104399501A discloses epsilon-Fe suitable for low temperature Fischer-Tropsch synthesis reaction 2 C, a nanoparticle preparation method. The initial precursor is skeleton iron, and the reaction system is intermittent discontinuous reaction of polyglycol solvent. CO of such a catalyst 2 Selectivity is 18.9%, CH 4 The selectivity bit of (2) 17.3%. The disadvantage is that the reaction can not be continuously completed only when the reaction is applied to low temperatures below 200 ℃. This means that such catalysts are not suitable for continuous production under modern fischer-tropsch synthesis industry conditions. However, since the skeleton iron cannot be completely carbonized, epsilon-Fe described in the publication 2 C nanoparticles contain a significant amount of iron impurity components other than iron carbide type, and in fact, the prior art has failed to obtain epsilon-Fe free of iron impurities 2 C pure phase material, wherein the Fe impurity is non- ε -Fe 2 C contains various Fe (element) phase components.
Therefore, improvements in iron-based catalysts used in fischer-tropsch synthesis reactions are needed.
Disclosure of Invention
The invention aims to solve the problem of how to obtain pure-phase iron carbide substances without Fe impurities by an iron-based catalyst, improve the stability of Fischer-Tropsch synthesis reaction and reduce CO at the same time 2 Or CH (CH) 4 The problem of too high a selectivity of by-products provides a composition containing precipitated epsilon/epsilon' iron carbide, a process for its preparation, a catalyst and its use, and a process for Fischer-Tropsch synthesis.
In order to achieve the above object, a first aspect of the present invention provides a composition containing precipitated epsilon/epsilon ' iron carbide, which comprises 95 to 100mol% of precipitated epsilon/epsilon ' iron carbide and 0 to 5mol% of Fe-containing impurities, which are iron-containing substances other than epsilon/epsilon ' iron carbide, based on the total amount of the composition; wherein the specific surface area of the composition is 20-260m 2 /g。
In a second aspect, the invention provides a method of preparing a composition comprising precipitated epsilon/epsilon' iron carbide, comprising:
(1) Mixing an aqueous solution containing ferric salt with an alkaline precipitant for coprecipitation, washing and separating the obtained precipitate, and drying and roasting the obtained solid to obtain a precursor;
(2) Combining the precursor with H 2 Precursor reduction is carried out at the temperature of 450-580 ℃;
(3) Mixing the material obtained in the step (2) with H 2 Pretreating CO at 90-185 deg.C, H 2 The molar ratio of the catalyst to CO is 1.2-2.8:1, a step of;
(4) Mixing the material obtained in the step (3) with H 2 Preparing carbide by CO at 200-300 deg.C, H 2 The molar ratio of the catalyst to CO is 1 to 3.2:1, obtaining precipitated epsilon/epsilon' iron carbide;
(5) Mixing 95-100 mole parts of precipitated epsilon/epsilon' iron carbide with 0-5 mole parts of Fe-containing impurities under the protection of inert gas;
wherein the Fe-containing impurities are iron-containing substances other than epsilon/epsilon' iron carbide.
In a third aspect, the present invention provides a precipitated epsilon/epsilon iron carbide-containing composition made by the method of the present invention.
In a fourth aspect, the present invention provides a catalyst comprising the precipitated epsilon/epsilon iron carbide-containing composition provided herein.
In a fifth aspect, the invention provides the use of a composition or catalyst comprising precipitated epsilon/epsilon' iron carbide as provided herein in a Fischer-Tropsch synthesis reaction.
In a sixth aspect the present invention provides the use of a precipitated epsilon/epsilon' iron carbide-containing composition or catalyst as provided herein in a fischer-tropsch based synthesis reaction of C, H fuels and/or chemicals.
In a seventh aspect the invention provides a method of fischer-tropsch synthesis comprising: the synthesis gas is contacted with the precipitated epsilon/epsilon' iron carbide-containing composition or catalyst provided herein under fischer-tropsch reaction conditions.
In an eighth aspect the invention provides a method of fischer-tropsch synthesis comprising: the synthesis gas is contacted with a Fischer-Tropsch catalyst under Fischer-Tropsch reaction conditions, wherein the Fischer-Tropsch catalyst comprises a Mn component and the precipitated epsilon/epsilon' iron carbide-containing composition provided herein.
Through the technical scheme, the invention has the following technical effects:
(1) The required raw materials are simple and easy to obtain, and the cost is low: the main raw material iron source of the synthesis precursor can be commercial ferric salt, and when active phase carbide is synthesized, only the original reaction gas (carbon monoxide and hydrogen) of a Fischer-Tropsch synthesis reaction system is utilized, and no inorganic or organic reaction raw material is involved, so that compared with the prior art, the method is greatly simplified;
(2) The operation steps are simple, and in the preferred embodiment, the preparation of the active phase can be realized in situ in the same reactor by only three steps of precursor reduction, pretreatment and carbide preparation in the whole process of preparing the precipitated epsilon/epsilon' iron carbide.
(3) The method can prepare 100% purity precipitated epsilon/epsilon' iron carbide, and can be combined with Fe-containing impurities to form a composition, and further combined with an auxiliary agent to form a catalyst. The 100% purity precipitated epsilon/epsilon 'iron carbide or composition or catalyst can be used in a high-temperature high-pressure (for example, the temperature of 235-250 ℃ and the pressure of 2.3-2.5 MPa) continuous reactor, has extremely high reaction stability, and breaks through the theory of traditional literature' at higher chemical potential mu of carbon C Under the theoretical technical barrier that epsilon/epsilon' iron carbide needs to exist stably under mild conditions of less than 200 ℃, the stable temperature can reach 250 ℃ and CO 2 The selectivity is extremely low: under the condition of industrial Fischer-Tropsch synthesis reaction, a high-pressure continuous reactor can be used for maintaining continuous stable reaction for more than 400 hours, and CO thereof 2 The selectivity is below 5% (preferably below 2.5%); at the same time, its by-product CH 4 The selectivity is also kept at 13.5 percent (preferably, the selectivity can reach below 9.5 percent), the selectivity of the effective product can reach above 80 percent (preferably, the selectivity can reach above 88 percent), and the method is very suitable for the high-efficiency production of the oil wax product in the industry of modern coal industry and Fischer-Tropsch synthesis.
Drawings
FIG. 1 is an in situ XRD spectrum of a process for preparing precipitated epsilon/epsilon' iron carbide in accordance with example 1 provided herein; wherein, before the reduction of the A-precursor, after the reduction of the B-precursor, the preparation of the D-iron carbide is completed after the C-pretreatment.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The first aspect of the present invention provides a composition comprising precipitated epsilon/epsilon ' iron carbide, said composition comprising 95 to 100 mole% of precipitated epsilon/epsilon ' iron carbide and 0 to 5 mole% of Fe-containing impurities, based on the total amount of said composition, said Fe-containing impurities being iron-containing species other than epsilon/epsilon ' iron carbide; wherein the specific surface area of the composition is 20-260m 2 /g。
The invention provides a composition containing precipitated epsilon/epsilon ' iron carbide, wherein epsilon/epsilon ' iron carbide contains epsilon-iron carbide with the purity of 100% and epsilon ' -iron carbide with the purity of 100%. Further, the precipitated epsilon/epsilon' iron carbide may be combined with other Fe-containing impurities to form a composition. Under the limitation of the content, when the composition containing the precipitated epsilon/epsilon' iron carbide provided by the invention can be applied to a Fischer-Tropsch synthesis catalyst, the composition can be singly used or combined with other components, so that the stability of the Fischer-Tropsch synthesis catalyst in the Fischer-Tropsch synthesis reaction can be improved, and the CO can be greatly reduced 2 Or CH (CH) 4 By-product selectivity.
In some embodiments of the invention, the composition contains high purity precipitated epsilon/epsilon 'iron carbide, and XRD and Mossburg spectroscopy analysis can be performed to observe that the crystal phase is pure epsilon/epsilon' iron carbide on the obtained XRD pattern and Mossburg spectroscopy results. Preferably, the specific surface area of the composition is 25-200m 2 And/g. The specific surface area can be determined by N 2 Is determined by BET adsorption and desorption methods. The composition comprises hexagonal, pseudo-hexagonal or trigonal epsilon/epsilon' iron carbide.
In some embodiments of the invention, it is further preferred that the composition comprises 97-100 mole% precipitated epsilon/epsilon iron carbide and 0-3 mole% Fe-containing impurities, based on the total amount of the composition. Can be determined by XRD and Mossburg spectrometry analysis, and can also be determined according to the preparation feeding amount of the composition.
In some embodiments of the invention, the Fe-containing impurity is at least one of iron carbide, iron oxide, iron hydroxide, iron sulfide, iron salt other than epsilon/epsilon' iron carbide. The Fe-containing impurities may be introduced by solution impregnation, sputtering, atomic deposition or mixing.
In a second aspect, the invention provides a method of preparing a composition comprising precipitated epsilon/epsilon' iron carbide, comprising:
(1) Mixing an aqueous solution containing ferric salt with an alkaline precipitant for coprecipitation, washing and separating the obtained precipitate, and drying and roasting the obtained solid to obtain a precursor;
(2) Combining the precursor with H 2 Precursor reduction is carried out at the temperature of 450-580 ℃;
(3) Mixing the material obtained in the step (2) with H 2 Pretreating CO at 90-185 deg.C, H 2 The molar ratio of the catalyst to CO is 1.2-2.8:1, a step of;
(4) Mixing the material obtained in the step (3) with H 2 Preparing carbide by CO at 200-300 deg.C, H 2 The molar ratio of the catalyst to CO is 1 to 3.2:1, obtaining precipitated epsilon/epsilon' iron carbide;
(5) Mixing 95-100 mole parts of precipitated epsilon/epsilon' iron carbide with 0-5 mole parts of Fe-containing impurities under the protection of inert gas;
wherein the Fe-containing impurities are iron-containing substances other than epsilon/epsilon' iron carbide.
In some embodiments of the present invention, the iron salt may be a water-soluble iron salt commonly used in the art, selected from water-soluble iron salts, and may be commercially available, for example, the iron salt is at least one of ferric nitrate, ferric chloride, ferrous ammonium sulfate, and ferric ammonium citrate.
In some embodiments of the present invention, the alkaline precipitant may be selected as is conventional in the art, for example, the alkaline precipitant is at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, and aqueous ammonia.
In a preferred embodiment of the present invention, the drying and roasting process includes: firstly, drying the solid for 6-10 hours at the temperature of 35-80 ℃ and the vacuum degree of 250-1200 Pa; drying the dried material at 75-180 ℃ for 3-24 hours, and roasting the obtained material at 250-580 ℃ for 1-10 hours. The drying process can be performed in an oven, and the roasting process can be performed in a muffle furnace.
In some embodiments of the present invention, the step (2) may function to generate nano iron powder in situ from the iron element in the precursor and reduce the generated nano iron powder.
In some embodiments of the invention, H in step (2) 2 Can be H 2 The flow is introduced into the reaction system and at the same time, H is controlled 2 The pressure of the stream controls the pressure of the precursor reduction, preferably in step (2), the pressure of the precursor reduction is 0.1 to 15atm, preferably 0.3 to 2.6atm, for a time of 0.7 to 15 hours, preferably 1 to 12 hours.
In some embodiments of the invention, H 2 The amount of (2) may be selected according to the amount of precursor to be treated, preferably H in step (2) 2 The gas flow rate of (C) is 600-25000mL/h/g, more preferably 2800-22000mL/h/g.
In the step (3) of the method provided by the invention, H 2 And CO can be (H) 2 +CO) mixed gas flow is introduced to participate in the pretreatment process; at the same time, by controlling (H 2 +co) pressure of the mixed gas stream to control the pressure of the pretreatment process. Preferably, in step (3), the pre-treatment is performed at a pressure of 0.05 to 7atm, preferably 0.08 to 4.5atm, for a time of 15 to 120min, preferably 20 to 90min.
In some embodiments of the present invention, preferably, in step (3), H 2 The total gas flow with CO is 300-12000mL/h/g, more preferably 1500-9000mL/h/g.
In step (4) of the method provided by the invention, conditions are provided to achieve the carbide preparation to obtain precipitated epsilon/epsilon' iron carbide. H 2 And CO can be (H) 2 +co) mixingIntroducing the gas flow into the carbide preparation process; at the same time, by controlling (H 2 +co) pressure of the mixed gas stream to control the pressure of the carbide manufacturing process. Preferably, in step (4), the carbide is prepared at a pressure of 0.1 to 10atm, preferably 0.2 to 4.5atm, for a time of 1.5 to 15 hours, preferably 2.5 to 12 hours.
In some embodiments of the invention, preferably, in step (4), H 2 The total gas flow with CO is 500-30000mL/h/g, more preferably 3000-25000mL/h/g.
In a preferred embodiment of the present invention, the carbide preparation further comprises: and (3) simultaneously carrying out temperature rising operation in the step (4), and rising the temperature from the temperature of the pretreatment to 200-300 ℃ at a temperature rising rate of 0.2-5 ℃/min. In this preferred embodiment, the resulting precipitated epsilon/epsilon' iron carbide may have better effective product selectivity in the Fischer-Tropsch reaction. Further preferably, the temperature from the pretreatment is raised to 210-290 ℃ at a temperature raising rate of 0.2-2.5 ℃/min. In the temperature raising operation, the temperature of the pretreatment is 90-185 ℃ in the step (3). Namely, the temperature raising operation is: the temperature is raised from 90 to 185℃to 200 to 300℃in step (4) at a temperature-raising rate of 0.2 to 5℃per minute, preferably from 90 to 185℃to 210 to 290℃at a temperature-raising rate of 0.2 to 2.5℃per minute.
In the present invention, "mL/h/g" refers to the volume of air intake per gram of material per hour during the iron carbide production process, unless otherwise specified.
In a preferred embodiment of the present invention, the precursor reduction, pretreatment and carbide preparation processes may be performed continuously in the same reactor. In-situ characterization equipment can be used for tracking the crystal phase transition of materials in the preparation process. In-situ characterization equipment can be used for tracking the crystal phase transition of materials in the preparation process.
In some embodiments of the invention, obtaining precipitated epsilon/epsilon' iron carbide can be accomplished by the process of steps (1) through (4). Can be determined by XRD and/or musburg spectroscopy.
In some embodiments of the present invention, the Fe-containing impurities contained in the precipitated epsilon/epsilon' iron carbide-containing composition may be admixed by means of an external addition. Preferably, in step (5), 97-100 mole parts of precipitated epsilon/epsilon' iron carbide is mixed with 0-3 mole parts of Fe-containing impurities.
In one embodiment, in the step (5), the powder of the precipitated epsilon/epsilon' iron carbide and the powder containing Fe impurity are mixed according to the dosage requirement in a glove box under the protection of inert gas.
In a third aspect, the present invention provides a precipitated epsilon/epsilon iron carbide-containing composition made by the process of the present invention. The composition comprises 95-100mol% of precipitated epsilon/epsilon 'iron carbide and 0-5mol% of Fe-containing impurities, based on the total amount of the composition, wherein the Fe-containing impurities are iron-containing substances other than epsilon/epsilon' iron carbide.
Preferably, the composition comprises 97-100mol% precipitated epsilon/epsilon' iron carbide and 0-3mol% Fe-containing impurities.
Preferably, the specific surface area of the composition is in the range of 20-260m 2 /g, preferably 25-200m 2 /g。
In a fourth aspect, the present invention provides a catalyst comprising the precipitated epsilon/epsilon iron carbide-containing composition provided herein. Preferably, the catalyst may also comprise other components, such as adjuvants.
In the specific embodiment provided by the invention, preferably, the content of the precipitated epsilon/epsilon' -containing iron carbide composition is more than 75wt% and less than 100wt% and the content of the auxiliary agent is more than 0wt% and less than 25wt%, based on the total amount of the catalyst.
In the specific embodiment provided by the invention, the catalyst can be prepared by introducing the auxiliary agent by a dipping, atomic deposition, sputtering or chemical deposition method.
In a fifth aspect, the invention provides the use of a composition or catalyst comprising precipitated epsilon/epsilon' iron carbide as provided herein in a Fischer-Tropsch synthesis reaction.
In a sixth aspect the present invention provides the use of a precipitated epsilon/epsilon' iron carbide-containing composition or catalyst as provided herein in a fischer-tropsch based synthesis reaction of C, H fuels and/or chemicals.
In a seventh aspect the invention provides a method of fischer-tropsch synthesis comprising: the synthesis gas is contacted with the precipitated epsilon/epsilon' iron carbide-containing composition or catalyst provided herein under fischer-tropsch reaction conditions.
The Fischer-Tropsch reaction may be carried out at elevated temperature and pressure using the precipitated epsilon/epsilon' iron carbide-containing compositions or catalysts of the present invention, for example, the Fischer-Tropsch reaction conditions include: the temperature is 235-250 ℃ and the pressure is 2.3-2.5MPa.
In the present invention, unless otherwise specified, the pressure refers to gauge pressure.
In some embodiments of the invention, preferably, the Fischer-Tropsch synthesis reaction is carried out in a high temperature, high pressure continuous reactor. The composition or the catalyst containing the precipitated epsilon/epsilon' iron carbide can realize that the Fischer-Tropsch synthesis reaction can keep continuous stable reaction for more than 400 hours in a high-temperature high-pressure continuous reactor.
In an eighth aspect the invention provides a method of fischer-tropsch synthesis comprising: the synthesis gas is contacted with a Fischer-Tropsch catalyst under Fischer-Tropsch reaction conditions, wherein the Fischer-Tropsch catalyst comprises a Mn component and the precipitated epsilon/epsilon' iron carbide-containing composition provided herein.
In the specific embodiment provided by the invention, the composition of the Fischer-Tropsch catalyst can be further based on the total amount of the Fischer-Tropsch catalyst, the content of the composition containing precipitated epsilon/epsilon' iron carbide is more than 75wt% and less than 100wt%, and the content of Mn is more than 0wt% and less than 25 wt%. In the fischer-tropsch catalyst, mn may be present in the form of oxides and may be introduced into the fischer-tropsch catalyst by methods including, but not limited to, impregnation, chemical deposition, sputtering, atomic deposition.
The present invention will be described in detail by examples. In the following examples and comparative examples,
in-situ XRD detection during the preparation of the iron carbide is carried out by using an X-ray diffractometer (Rigaku company, model D/max-2600/PC) to monitor the crystal phase change of the material;
the carbonization obtainedThe iron and iron carbide compositions were prepared using a musburger spectrometer (Transmission 57 Fe， 57 Carrying out Mossburger spectrum detection by a Co (Rh) source sine velocity spectrometer;
the BET specific surface area of the iron carbide composition is determined by nitrogen adsorption;
in the Fischer-Tropsch synthesis:
carrying out gas chromatographic analysis (Agilent 6890 gas chromatography) on the product obtained by the reaction;
the reaction effect is calculated by the following formula:
CO 2 selectivity% 2 Mole/(mole of CO in feed-mole of CO in discharge)]×100％；
CH 4 Selectivity = [ CH in discharge ] 4 Mole/(mole of CO in feed-mole of CO in discharge)]×100％；
Effective product selectivity% = [1-CO 2 Selectivity% -CH 4 Selectivity%]×100％；
Space-time conversion rate (mmol/h/g) of raw material CO Fe ) = (moles of CO in feed-moles of CO in discharge)/reaction time/weight of Fe element;
space-time yield (mmol/h/g) of the effective product Fe ) C of the product 2 C (C) 2 The above hydrocarbon has carbon mole number/reaction time/Fe element weight.
Example 1
(1) Mixing ferric ammonium citrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 2.6atm, H 2 22000mL/h/g, and reducing the precursor for 1h at the temperature of 580 ℃;
(3) Cooling the product obtained in the step (2) to 160 ℃, and reacting with H at 160 DEG C 2 The mixture with CO (pressure 4.5atm, total gas flow 9000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 20min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 4.5atm, total gas flow 25000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 160 ℃ to 290 ℃ at the heating rate of 2.5 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 2.5h, and the precipitated iron carbide is obtained, and is measured as pure epsilon/epsilon' iron carbide by Mosburgh spectrum and is recorded as precipitated iron carbide 1;
(5) Under the protection of Ar gas, 97 mole parts of precipitated iron carbide 1 and 3 mole parts of ferrous oxide (i.e. Fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition 1.
Example 2
(1) Mixing ferric nitrate with the concentration of 0.7mol/L and sodium carbonate solution with the concentration of 0.8mol/L at the temperature of 40 ℃ and the pH value of 7.0 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 7h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 0.3atm, H 2 28000mL/h/g, and reducing the precursor for 12h at 450 ℃;
(3) Cooling the product obtained in the step (2) to 160 ℃, and reacting with H at 160 DEG C 2 Mixed gas with CO (pressure 0.08atm, total gas flow 1500mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 90min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 0.2atm, total gas flow 3000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 160 ℃ to 210 ℃ at the heating rate of 0.2 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 12h, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 2;
(5) 99 mole parts of precipitated iron carbide 2 are mixed with 1 mole part of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this was designated iron carbide composition 2.
Example 3
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium bicarbonate solution with the concentration of 0.5mol/L at the temperature of 70 ℃ and the pH value of 6.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at the temperature of 110 ℃ for 20h, and roasting at the temperature of 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 3;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 3 and 2 mole parts of ferrous oxide (i.e. Fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition 3.
Example 4
(1) - (4) the method of example 1 was followed except that the precursor was used with H 2 At a pressure of 3atm ", the precursor is replaced with H 2 At a pressure of 2.6atm ", precipitated iron carbide was obtained, which was measured by musburg spectroscopy as pure epsilon/epsilon' iron carbide, designated as precipitated iron carbide 4.
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 4 and 2 mole parts of ferrous oxide (i.e. Fe-containing impurities) are mixed. After mixing, this was designated iron carbide composition 4.
Example 5
(1) - (4) the method of example 1 was followed except that the precursor was used with H 2 At a pressure of 0.08atm ", the" precursor and H "are replaced 2 At a pressure of 2.6atm ", precipitated iron carbide was obtained, which was measured by musburg spectroscopy as pure epsilon/epsilon' iron carbide, designated as precipitated iron carbide 5.
(5) 97 mole parts of precipitated iron carbide 5 and 3 mole parts of ferrous oxide (i.e., fe-containing impurities) were mixed under Ar gas protection. After mixing, this was designated as iron carbide composition 5.
Example 6
(1) Mixing 1.2mol/L ferrous ammonium sulfate and 0.3mol/L potassium carbonate solution at 50 ℃ and pH=5.8 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 390 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 13h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 6;
(5) 99 mole parts of precipitated iron carbide 6 are mixed with 1 mole part of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this was designated iron carbide composition 6.
Example 7
(1) Mixing ferric chloride with the concentration of 1.0mol/L and potassium hydroxide solution with the concentration of 0.7mol/L at 70 ℃ and the pH=7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 0.5h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃ and at 150 DEG CAnd H is 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured to be pure epsilon/epsilon' iron carbide by Mossburg spectrum and is marked as precipitated iron carbide 7;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 7 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) are mixed. After mixing, this was designated iron carbide composition 7.
Example 8
(1) Mixing ferric chloride with the concentration of 1.5mol/L with sodium bicarbonate solution with the concentration of 0.5mol/L at 50 ℃ and the pH=7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 450 ℃ for 7h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 23000mL/h/g, and reducing the precursor at 500 ℃ for 6h;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured to be pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 8;
(5) 97 mole parts of precipitated iron carbide 8 were mixed with 3 mole parts of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this was designated as iron carbide composition 8.
Example 9
(1) Mixing ferric nitrate with the concentration of 2.0mol/L and potassium bicarbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of the catalyst is 400mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured to be pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 9;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 9 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition 9.
Example 10
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.5 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 6atm, total gas flow 6000mL/H/g, H) 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 10;
(5) 99 parts by mole of precipitated iron carbide 10 are mixed with 1 part by mole of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this is designated as iron carbide composition 10.
Example 11
(1) Mixing ferric nitrate with the concentration of 1.0mol/L with sodium hydroxide solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 8h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 0.04atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 11;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 11 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition 11.
Example 12
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.3mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 100min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide through Mossburg spectrum and is recorded as precipitated iron carbide 12;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 12 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) are mixed. After mixing, this is denoted as iron carbide composition 12.
Example 13
(1) Mixing ferric nitrate with the concentration of 1.0mol/L with 0.8mol/L ammonia water solution at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 550 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 10min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 Molar ratio to CO of1.5:1, then heating from 150 ℃ to 250 ℃ at a heating rate of 2.0 ℃/min under the condition, and then preparing carbide with the material obtained in the step (3) for 6 hours to obtain precipitated iron carbide, wherein the precipitated iron carbide is measured by Mossburg spectroscopy to be pure epsilon/epsilon' iron carbide and is recorded as precipitated iron carbide 13;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 13 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) were mixed. After mixing, this was designated as iron carbide composition 13.
Example 14
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of=6.2 to obtain precipitate slurry, washing the precipitate slurry by deionized water, filtering the precipitate slurry to obtain a filter cake, drying the filter cake at the temperature of 120 ℃ for 24h, and roasting the filter cake at the temperature of 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 The mixture with CO (pressure 2.0atm, total gas flow 10000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 14;
(5) 97 parts by mole of precipitated iron carbide 14 was mixed with 3 parts by mole of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this is denoted as iron carbide composition 14.
Example 15
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of=6.3 to obtain precipitate slurry, washing the precipitate slurry by deionized water, filtering the precipitate slurry to obtain a filter cake, drying the filter cake at the temperature of 120 ℃ for 24h, and roasting the filter cake at the temperature of 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 The mixture with CO (pressure 2.0atm, total gas flow 200mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 15;
(5) 97 parts by mole of precipitated iron carbide 15 was mixed with 3 parts by mole of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this is designated iron carbide composition 15.
Example 16
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at the temperature of 100 ℃ for 24h, and roasting at the temperature of 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 5atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the catalyst to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, and then carbide preparation is carried out on the catalyst and the material obtained in the step (3), wherein the carbonization time is as follows6h, obtaining precipitated iron carbide, namely pure epsilon/epsilon 'iron carbide measured by Mossburg spectrum, and marking the pure epsilon/epsilon' iron carbide as precipitated iron carbide 16;
(5) 97 parts by mole of precipitated iron carbide 16 was mixed with 3 parts by mole of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this is denoted as iron carbide composition 16.
Example 17
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 30 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 0.08atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 17;
(5) Under the protection of Ar gas, 98 parts by mole of precipitated iron carbide 17 was mixed with 2 parts by mole of ferrous oxide (i.e., fe-containing impurities). After mixing, this was designated iron carbide composition 17.
Example 18
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at 50 ℃ and the pH=7.8 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 12000mL/h/g at 500 DEG CPrecursor reduction is carried out for 6h;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 13h, precipitated iron carbide is obtained, and the precipitated iron carbide is measured to be pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 18;
(5) Under the protection of Ar gas, 98 parts by mole of precipitated iron carbide 18 was mixed with 2 parts by mole of ferrous oxide (i.e., fe-containing impurities). After mixing, this is denoted as iron carbide composition 18.
Example 19
(1) Mixing ferric nitrate with the concentration of 1.2mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 40 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 1h, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 19;
(5) Under the protection of Ar gas, 98 parts by mole of precipitated iron carbide 19 was mixed with 2 parts by mole of ferrous oxide (i.e., fe-containing impurities). After mixing, this is designated as iron carbide composition 19.
Example 20
(1) Mixing ferric nitrate with the concentration of 1.2mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 26000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 20;
(5) 99 parts by mole of precipitated iron carbide 20 are mixed with 1 part by mole of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this is denoted as iron carbide composition 20.
Example 21
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.0 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 With COMixed gas (pressure 2.0atm, total gas flow 6000mL/H/g, H) 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 400mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 21;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 21 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) were mixed. After mixing, this was designated as iron carbide composition 21.
Example 22
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 10h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 295 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, and precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is marked as precipitated iron carbide 22;
(5) 97 mole parts of precipitated iron carbide 22 was mixed with 3 mole parts of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this is denoted as iron carbide composition 22.
Example 23
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 450 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 190 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured as pure epsilon/epsilon' iron carbide by Mossburg spectrum and is recorded as precipitated iron carbide 23;
(5) Under the protection of Ar gas, 98 mole parts of precipitated iron carbide 23 and 2 mole parts of ferrous oxide (i.e., fe-containing impurities) are mixed. After mixing, this is designated as iron carbide composition 23.
Example 24
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 5.9 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 4.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, precipitated iron carbide is obtained, and the precipitated iron carbide is measured to be pure epsilon/epsilon' iron carbide through Mossburg spectrum and is recorded as precipitated iron carbide 24;
(5) Under the protection of Ar gas, 98 parts by mole of precipitated iron carbide 24 was mixed with 2 parts by mole of ferrous oxide (i.e., fe-containing impurities). After mixing, this is denoted as iron carbide composition 24.
Comparative example 1
(1) Mixing ferric nitrate with the concentration of 1.7mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 430 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, and the precipitated iron carbide is obtained and is marked as iron carbide D1;
(5) Under the protection of Ar gas, 98 mole parts of iron carbide D1 and 2 mole parts of ferrous oxide (namely Fe-containing impurities) are mixed. After mixing, the mixture was designated as iron carbide composition D1.
Comparative example 2
(1) (1) mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.9mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain a precipitation slurry, washing the precipitation slurry by deionized water, filtering the precipitation slurry to obtain a filter cake, drying the filter cake at the temperature of 120 ℃ for 24 hours, and roasting the filter cake at the temperature of 350 ℃ for 3 hours to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 190 ℃, and reacting with H at 190 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 190 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, and the precipitated iron carbide is obtained and is marked as iron carbide D2;
(5) Under the protection of Ar gas, 98 mole parts of iron carbide D2 and 2 mole parts of ferrous oxide (namely Fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition D2.
Comparative example 3
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at 50 ℃ and the pH=7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 380 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 3:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the catalyst to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, and then carbide preparation is carried out on the catalyst and the material obtained in the step (3), wherein the carbonization time is as follows6h, obtaining precipitated iron carbide which is marked as iron carbide D3;
(5) 99 parts by mole of iron carbide D3 are mixed with 1 part by mole of ferrous oxide (i.e., fe-containing impurities) under Ar gas protection. After mixing, this was designated as iron carbide composition D3.
Comparative example 4
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.9mol/L at 50 ℃ and the pH=7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 0.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 2.0 ℃/min under the condition, and then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, and the precipitated iron carbide is obtained and is marked as iron carbide D4;
(5) Under the protection of Ar gas, 98 mole parts of iron carbide D4 and 2 mole parts of ferrous oxide (namely Fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition D4.
Comparative example 5
(1) Mixing ferric nitrate with the concentration of 1.1mol/L and ammonium carbonate solution with the concentration of 0.3mol/L at the temperature of 60 ℃ and the pH value of 7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 350 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 250 ℃ at the heating rate of 0.1 ℃/min under the condition, and then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, and the precipitated iron carbide is obtained and is marked as iron carbide D5;
(5) 97 parts by mole of iron carbide D5 and 3 parts by mole of ferrous oxide (i.e., fe-containing impurities) were mixed under Ar gas protection. After mixing, this was designated as iron carbide composition D5.
Comparative example 6
(1) Mixing ferric nitrate with the concentration of 1.0mol/L and ammonium carbonate solution with the concentration of 0.8mol/L at 50 ℃ and the pH=7.2 to obtain precipitate slurry, washing with deionized water, filtering to obtain a filter cake, drying at 120 ℃ for 24h, and roasting at 390 ℃ for 5h to obtain a precursor.
(2) Precursor and H 2 At a pressure of 1.5atm, H 2 The flow rate of 12000mL/h/g, and the precursor is reduced for 6h at the temperature of 500 ℃;
(3) Cooling the product obtained in the step (2) to 150 ℃, and reacting with H at 150 DEG C 2 Mixed gas with CO (pressure 2.0atm, total gas flow 6000mL/H/g, H 2 Contact with CO in a molar ratio of 2:1) for pretreatment for 45min;
(4) Will H 2 The condition of the mixed gas with CO is as follows: pressure 2.0atm, total gas flow 12000mL/H/g, H 2 The molar ratio of the iron carbide to CO is 1.5:1, the temperature is increased from 150 ℃ to 310 ℃ at the heating rate of 1.5 ℃/min under the condition, then carbide preparation is carried out on the iron carbide and the material obtained in the step (3), the carbonization time is 6 hours, and the precipitated iron carbide is recorded as iron carbide D6;
(5) Under the protection of Ar gas, 98 mole parts of iron carbide D6 and 2 mole parts of ferrous oxide (namely Fe-containing impurities) are mixed. After mixing, this was designated as iron carbide composition D6.
Comparative example 7
According to the method of example 1, except that (5) 92 parts by mole of precipitated iron carbide 1 and 8 parts by mole of ferrous oxide (i.e., fe-containing impurities) were mixed under Ar gas. After mixing, this was designated as iron carbide composition D7.
Examples 25 to 48
Taking iron carbide compositions 1-24, respectively, in N 2 Under protection, respectively adding manganese citrate solution by impregnation method, and adding N at 25deg.C 2 And drying the air flow for 24 hours to obtain the Fischer-Tropsch catalyst 1-24. Wherein the amount of manganese citrate solution added is impregnated such that the resulting Fischer-Tropsch catalyst 1-24 contains 85wt% iron carbide composition 1-24, 15wt% MnO, respectively 2 。
Comparative examples 8 to 14
Taking iron carbide compositions D1-D7, respectively, in N 2 Under protection, respectively adding manganese citrate solution by impregnation method, and adding N at 25deg.C 2 And drying the air flow for 24 hours to obtain the Fischer-Tropsch catalysts D1-D7. Wherein the amount of manganese citrate solution added is impregnated such that the resulting Fischer-Tropsch catalysts D1-D7 respectively contain 85wt% of the iron carbide composition D1-D7, 15wt% of MnO 2 。
Test case
XRD and Mossburg spectrum measurements were performed on iron carbide 1-24 and D-D6, and the measured Fe compound content results are shown in Table 1. Wherein the content unit of Fe compound is mole percent.
TABLE 1
The whole process of preparing the iron carbide 1 in the embodiment 1 adopts an in-situ XRD detection technology, and an X-ray diffractometer (Rigaku company, model D/max-2600/PC) is used for monitoring the crystal phase change of the material. As shown in FIG. 1, curve A shows the result before the precursor reduction in step (1), B shows the result after the precursor reduction in step (1), C shows the result after the pretreatment in step (2), and D shows the result after the carbide preparation in step (3). Wherein curve A is alpha-Fe 2 O 3 The characteristic peaks 2θ=33.3°, 35.7 °, 41.0 °, 49.5 °, 54.2 °, 57.6 °, 62.7 ° are completely consistent with the standard card PDF-02-0919. B is an alpha-Fe crystal phase, and curve C is an alpha-Fe crystal phase with a trace carbon atom layer generated on the surface, wherein characteristic peaks 2 theta = 44.7 degrees, 65.0 degrees and 82.3 degrees are consistent with XRD standard cards PDF-65-4899 of the alpha-Fe. Curve D is 100% pure ε -Fe 2 C and ε -Fe 2.2 C, namely epsilon/epsilon' iron carbide, and together with an XRD standard card PDF-89-2005, curve D shows that 2θ=37.7°, 41.4 °, 43.2 °, 57.2 °, 68.0 °, 76.8 ° and 82.9 ° are completely consistent with the standard card. The obtained spectrogram can clearly see the change process from nano iron powder to target carbide. The produced target product epsilon/epsilon 'iron carbide has good crystallinity, well corresponds to all characteristic peaks of epsilon/epsilon' iron carbide, has extremely high purity and does not contain any other impurities.
The pure-phase epsilon/epsilon' iron carbide obtained in other examples also has similar spectrograms as described above, and will not be described again. The iron carbides obtained in comparative examples 1 to 6, however, did not have pure phase epsilon/epsilon' iron carbide, and the spectrum shown in FIG. 1 was not obtained.
Mossburg spectra and BET specific surface areas were measured for iron carbide compositions 1-24 and D1-D7, respectively, and the results are shown in Table 2.
TABLE 2
Note that: in the iron carbide compositions D1-D6, the iron carbides D1-D6 were not precipitated 100% pure ε/ε 'iron carbides, and Table 1 shows the ε/ε' iron carbide content of the iron carbides D1-D6. The content of epsilon/epsilon 'iron carbide in the iron carbide compositions D1-D6 was determined based on the Guan Tanhua iron D1-D6 data of comparative examples 1-6, and the epsilon/epsilon' iron carbide data of Table 1.
Evaluation example
Catalytic reaction performance was evaluated for Fischer-Tropsch catalysts 1-24, fischer-Tropsch catalysts D1-D7, and iron carbide compositions 1-3, respectively, in a fixed bed continuous reactor. The catalyst loading was 10.0g.
Evaluation conditions: t=248 ℃, p=2.45 mpa, h 2 ：CO＝1.8：1，(H 2 +co) total = 42000mL/h/g- Fe (standard state flow, relative to the Fe element). The reaction was carried out, and the reaction products were analyzed by gas chromatography, and the evaluation data of the reaction performance for 24 hours and 400 hours of the reaction were shown in tables 3 and 4.
TABLE 3 Table 3
TABLE 4 Table 4
As can be seen from the above examples, comparative examples and the data in tables 1-4, the precipitated epsilon/epsilon' iron carbide or composition or catalyst prepared by the present invention is subjected to Fischer-Tropsch synthesis under industrial conditions, exhibiting high space-time conversion of raw material CO over a limited range of conditions, better reactivity, and ultra-low CO 2 Selectivity. At the same time CH 4 The selectivity is low, and the selectivity of effective products is high.
Further conducting long-period experiments, it can be seen from the data of reaction 400h in Table 4 that the precipitated epsilon/epsilon' -containing iron carbide composition or catalyst prepared under the limiting conditions provided by the invention can maintain stable both CO conversion rate and product selectivity after long-term operation, has no obvious change, and has stability greatly superior to that of iron carbide in the prior art.
The precipitated epsilon/epsilon' iron carbide or the composition or the catalyst prepared under the limiting condition of the invention can be suitable for a high-temperature high-pressure continuous reactor, has high reaction stability and CO 2 The selectivity is extremely low: under the condition of industrial Fischer-Tropsch synthesis reaction, a high-pressure continuous reactor can be used for maintaining continuous stable reaction for more than 400 hours, and CO thereof 2 The selectivity is below 5% (preferably 2.5% or below); at the same time, its by-product CH 4 The selectivity is kept below 13.5% (preferably below 9.5%) and the selectivity of the effective product is above 80% (preferably above 88%). Wherein the space-time yield of the catalyst-effective product of the preferred conditions (catalysts 1 to 3) is up to 125mmol/h/g- Fe The method is very suitable for efficiently producing oil and wax products in the large industrial of the Fischer-Tropsch synthesis of the modern coal industry.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of individual specific technical features in any suitable way. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition. Such simple variations and combinations are likewise to be regarded as being within the scope of the present disclosure.
Claims (23)
1. A composition comprising precipitated epsilon/epsilon ' iron carbide, said composition comprising 95-100 mole% of precipitated epsilon/epsilon ' iron carbide and 0-5 mole% of Fe-containing impurities, based on the total amount of the composition, said Fe-containing impurities being iron-containing species other than epsilon/epsilon ' iron carbide;
Wherein the specific surface area of the composition is 20-260m 2 /g; the Fe-containing impurity is not 0;
the preparation method of the composition comprises the following steps:
(1) Mixing an aqueous solution containing ferric salt with an alkaline precipitant for coprecipitation, washing and separating the obtained precipitate, and drying and roasting the obtained solid to obtain a precursor;
(2) Combining the precursor with H 2 Precursor reduction is carried out at the temperature of 450-580 ℃;
(3) Mixing the material obtained in the step (2) with H 2 Pretreating CO at 90-185 deg.C, H 2 The molar ratio of the catalyst to CO is 1.2-2.8:1, a step of;
(4) Mixing the material obtained in the step (3) with H 2 Preparing carbide by CO at 200-300 deg.C, H 2 The molar ratio of the catalyst to CO is 1 to 3.2:1, obtaining precipitated epsilon/epsilon' iron carbide;
(5) 95-100 mole parts of precipitated epsilon/epsilon' iron carbide and 0-5 mole parts of Fe-containing impurities are mixed under the protection of inert gas.
2. The composition according to claim 1, wherein the specific surface area of the composition is 25-200m 2 /g。
3. Composition according to claim 1 or 2, wherein the composition comprises 97-100mol% precipitated epsilon/epsilon' iron carbide and 0-3mol% Fe-containing impurities, based on the total amount of the composition.
4. The composition of claim 1 or 2, wherein the Fe-containing impurity is at least one of iron carbide other than epsilon/epsilon' iron carbide, iron oxide, iron hydroxide, iron sulfide, iron salt.
5. A composition according to claim 3, wherein the Fe-containing impurity is at least one of iron carbide other than epsilon/epsilon' iron carbide, iron oxide, iron hydroxide, iron sulfide, iron salt.
6. A method of preparing a composition comprising precipitated epsilon/epsilon' iron carbide, comprising:
(1) Mixing an aqueous solution containing ferric salt with an alkaline precipitant for coprecipitation, washing and separating the obtained precipitate, and drying and roasting the obtained solid to obtain a precursor;
(2) Combining the precursor with H 2 Precursor reduction is carried out at the temperature of 450-580 ℃;
(3) Mixing the material obtained in the step (2) with H 2 Pretreating CO at 90-185 deg.C, H 2 The molar ratio of the catalyst to CO is 1.2-2.8:1, a step of;
(4) Mixing the material obtained in the step (3) with H 2 Preparing carbide by CO at 200-300 deg.C, H 2 The molar ratio of the catalyst to CO is 1 to 3.2:1, obtaining precipitated epsilon/epsilon' iron carbide;
(5) Mixing 95-100 mole parts of precipitated epsilon/epsilon' iron carbide with 0-5 mole parts of Fe-containing impurities under the protection of inert gas;
Wherein the Fe-containing impurities are iron-containing substances other than epsilon/epsilon' iron carbide.
7. The method of claim 6, wherein the iron salt is selected from water-soluble iron salts;
the alkaline precipitant is at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide and ammonia water;
and/or, the drying and roasting processes comprise: firstly, drying the solid for 6-10 hours at the temperature of 35-80 ℃ and the vacuum degree of 250-1200 Pa; drying the dried material at 75-180 ℃ for 3-24 hours, and roasting the obtained material at 250-580 ℃ for 1-10 hours.
8. The method of claim 7, wherein the iron salt is selected from at least one of ferric nitrate, ferric chloride, ferrous ammonium sulfate, and ferric ammonium citrate.
9. The method according to any one of claims 6 to 8, wherein in step (2), the precursor is reduced at a pressure of 0.1 to 15atm for a time of 0.7 to 15 hours;
and/or, in step (2), H 2 The gas flow rate of (2) is 600-25000mL/h/g.
10. The method of claim 9, wherein in step (2), the precursor is reduced at a pressure of 0.3-2.6atm for a time of 1-12 hours;
and/or, in step (2), H 2 The gas flow rate of (2) is 2800-22000mL/h/g.
11. The method according to any one of claims 6 to 8, wherein in step (3), the pretreatment is performed at a pressure of 0.05 to 7atm for 15 to 120 minutes;
and/or, in step (3), H 2 The total gas flow rate with CO is 300-12000mL/h/g.
12. The method of claim 11, wherein in step (3), the pre-treatment is performed at a pressure of 0.08-4.5atm for a time of 20-90min;
and/or, in step (3), H 2 The total gas flow rate with CO is 1500-9000mL/h/g.
13. The method according to any one of claims 6 to 8, wherein in the step (4), the carbide is prepared at a pressure of 0.1 to 10atm for a time of 1.5 to 15 hours;
and/or, in step (4), H 2 The total gas flow rate with CO is 500-30000mL/h/g.
14. The method according to claim 13, wherein in the step (4), the carbide is prepared at a pressure of 0.2-4.5atm for a time of 2.5-12 hours;
and/or, in step (4), H 2 The total gas flow rate with CO is 3000-25000mL/h/g.
15. The method of any of claims 6-8, wherein the carbide preparation further comprises: and (3) simultaneously carrying out temperature rising operation in the step (4), and rising the temperature from the temperature of the pretreatment to 200-300 ℃ at a temperature rising rate of 0.2-5 ℃/min.
16. The method of claim 15, wherein the temperature from the pretreatment is raised to 210-290 ℃ at a ramp rate of 0.2-2.5 ℃/min.
17. The method of any one of claims 6 to 8, wherein 97 to 100 parts by mole of precipitated epsilon/epsilon iron carbide is mixed with 0 to 3 parts by mole of Fe-containing impurities in step (5).
18. A catalyst comprising the precipitated epsilon/epsilon iron carbide-containing composition of any of claims 1-5.
19. Use of a composition comprising precipitated epsilon/epsilon' iron carbide as claimed in any one of claims 1 to 5 or of a catalyst as claimed in claim 18 in a fischer-tropsch synthesis reaction.
20. Use of a composition comprising precipitated epsilon/epsilon' iron carbide as claimed in any one of claims 1 to 5 or of a catalyst as claimed in claim 18 in a fischer-tropsch based synthesis reaction of C, H fuels and/or chemicals.
21. A method of fischer-tropsch synthesis comprising: contacting the synthesis gas with the precipitated epsilon/epsilon' iron carbide-containing composition of any one of claims 1 to 5 or the catalyst of claim 18 under fischer-tropsch synthesis reaction conditions.
22. The process of claim 21 wherein the fischer-tropsch synthesis is carried out in a high temperature, high pressure continuous reactor.
23. A method of fischer-tropsch synthesis comprising: contacting the synthesis gas with a fischer-tropsch catalyst under fischer-tropsch reaction conditions, wherein the fischer-tropsch catalyst comprises a Mn component and the precipitated epsilon/epsilon' iron carbide-containing composition of any of claims 1 to 5.
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