Iron-manganese based catalyst, preparation method and catalytic method thereof

Abstract

The present invention provides a catalyst comprising an iron species, manganese or an oxide thereof, cobalt or an oxide thereof, an alkali metal, and optionally at least one selected from the group consisting of zinc and copper, a process for preparing the catalyst, and a process for hydrogenating carbon dioxide and / or carbon monoxide to produce hydrocarbons using the catalyst.

Description

Technical Field

[0001] This description relates to hydrogenation catalysts, their precursors, and their use in processes suitable for converting carbon dioxide and / or carbon monoxide into hydrocarbons. In particular, the catalysts and processes described herein produce C 5+ hydrocarbons, particularly C 5+ α-olefins. Background Art

[0002] Olefins are widely used in the chemical industry as building blocks for manufacturing a wide range of products and as a major component of fuels. α-olefins have a double bond at the terminal or α-position, which enhances the reactivity at this position and makes them useful for producing detergents, lubricants, plasticizers, pharmaceuticals, fine chemicals, and polymers.

[0003] The catalytic preparation of hydrocarbons from synthesis gas is well-known and is generally referred to as Fischer-Tropsch synthesis. However, Fischer-Tropsch synthesis tends to promote the formation of saturated alkanes.

[0004] Furthermore, it is well-known that there is a need to reduce greenhouse gas (GHG) emissions in the transportation industry. Due to improved fuel efficiency, hydrogen fuel cells, and electric vehicles, the UK reduced its GHG emissions from road transportation by 8.6% between 2002 and 2012. However, emissions from the second-largest transportation segment - aviation - increased by approximately 6%.

[0005] Producing fuels from CO2 or CO can address the aforementioned energy needs while meeting environmental standards. However, state-of-the-art CO2-to-fuel conversion mainly produces C1 products (synthesis gas, formic acid, methanol), and less frequently produces C2 to C4 products such as mixed alcohols and olefins. These processes can produce long-chain hydrocarbon mixtures after methanol-to-olefin (MTO) or FT synthesis. However, directly obtaining fuels such as jet engine fuel via such routes is particularly challenging because they cannot produce the desired composition (i.e., containing C 5+ hydrocarbons) to meet strict, well-established standards.

[0006] There is a need for new high-performance catalysts and processes suitable for converting carbon dioxide and / or carbon monoxide into hydrocarbons. In particular, there is a need for inexpensive and abundant catalysts and methods using such catalysts that increase the conversion rate of carbon dioxide and / or carbon monoxide, and / or increase the yield of valuable hydrocarbons such as C 5+ hydrocarbons (including C 5+ (α) - olefins). Summary of the Invention

[0007] In a first aspect, the present invention relates to a catalyst precursor comprising an iron substance, an alkali metal or its salt, and a complexing agent.

[0008] In a second aspect, the present invention relates to a method for preparing a catalyst precursor, which comprises:

[0009] (a) combining (i) an iron substance, (ii) an alkali metal or a salt thereof, (iii) a complexing agent, and (iv) a solvent;

[0010] (b) stirring the mixture of step (a) to provide a homogeneous mixture;

[0011] (c) heating the mixture of step (b) to partially remove the solvent, thereby providing a slurry or a paste;

[0012] In a third aspect, the present invention relates to a catalyst precursor obtainable by the method of the second aspect.

[0013] In a fourth aspect, the present invention relates to a catalyst obtainable by activating a catalyst precursor according to the first aspect.

[0014] In a fifth aspect, the present invention relates to a method for preparing a catalyst, which comprises:

[0015] (a) providing a catalyst precursor according to the first or third aspect of the present invention;

[0016] (b) optionally calcining the catalyst precursor; and

[0017] (c) activating the precursor.

[0018] In a sixth aspect, the present invention relates to a catalyst obtainable by the method of the fifth aspect.

[0019] In a seventh aspect, the present invention relates to a method for the hydrogenation of carbon dioxide, the method comprising: contacting a feedstock comprising hydrogen and carbon dioxide with a catalyst precursor according to the first aspect or a catalyst according to the fourth or sixth aspect at elevated temperature and pressure.

[0020] In an eighth aspect, the present invention relates to a method for the hydrogenation of carbon monoxide, the method comprising: contacting a feedstock comprising hydrogen and carbon monoxide with a catalyst precursor according to the first aspect or a catalyst according to the fourth or sixth aspect at elevated temperature and pressure.

[0021] In a ninth aspect, the present invention relates to a method for producing olefins, the method comprising: contacting a feedstock comprising hydrogen and carbon dioxide and / or carbon monoxide with a catalyst precursor according to the first aspect or a catalyst according to the fourth or sixth aspect at elevated temperature and pressure.

[0022] In a tenth aspect, the present invention relates to a method for producing fuel, the method comprising: contacting a feedstock comprising hydrogen and carbon dioxide and / or carbon monoxide with a catalyst precursor according to the first aspect or a catalyst according to the fourth or sixth aspect at elevated temperature and pressure.

[0023] In an eleventh aspect, the present invention relates to a heterogeneous mixture comprising a catalyst precursor according to the first aspect or a catalyst according to the fourth or sixth aspect and a gas containing hydrogen and carbon monoxide and / or hydrogen and carbon dioxide.

[0024] The preferred, suitable and optional features of any particular aspect of the present invention are also the preferred, suitable and optional features of any other aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of an apparatus for evaluating catalyst performance is shown.

[0026] Figure 2 The molar ratio of olefins: alkanes in the liquid product produced after CO2 hydrogenation via Fe-Mn-K(100:10:5) [Catalyst 3], Fe-Mn-K(100:10:8) [Catalyst 5], Fe-Mn-K(100:20:5) [Catalyst 6] is shown.

[0027] Figures 3 to 7 XRD spectra of various CO2 hydrogenation catalysts are shown.

[0028] Figure 8 The GC-MS spectrum of the product curve after CO hydrogenation via a Fe-Co-Mn-Na(100:5:20:2) catalyst at 300 °C when the syngas feedstock is 1:1 (H2:CO) is shown.

[0029] Figure 9 The CO2 hydrogenation performance of the Fe-Mn-K catalyst is shown: (a) the conversion of CO2 and H2 over reaction time; (b) the selectivity of hydrocarbon products over reaction time.

[0030] Figure 10 The GC-MS spectrum of the fuel from CO2 hydrogenation via the Fe-Mn-K catalyst is shown.

[0031] Figure 11 XRD spectra of the Fe-Mn-K catalyst precursor, the activated catalyst and the used catalyst are shown.

[0032] Figure 12The XPS spectra of the Fe-Mn-K catalyst precursor are shown. 12a) The measured XPS spectrum of the Fe-Mn-K catalyst; 12b) The high-resolution XPS spectrum of Fe 2p.

[0033] Figure 13 The SEM images of a) the Fe-Mn-K catalyst precursor and b) the used catalyst are shown.

[0034] Figure 14 The HRTEM images of the Fe-Mn-K catalyst precursor (14a, 14b, 14c) and the used catalyst (14d, 14e, 14f) are shown. Detailed Description

[0035] Definitions

[0036] As used herein, the term "catalyst precursor" refers to a material used to prepare a catalytically active substance. Generally, the precursor is prepared by calcining its components. Generally, the catalyst precursor needs to be converted into a catalytically active substance, for example, by oxidation, reduction, and / or heat treatment, or a combination thereof. Suitably, it is activated via reduction. The catalyst precursor can be converted into a catalytically active substance (i.e., "activated") in situ (i.e., under reaction conditions), or the catalyst precursor can also be converted into a catalytically active substance before being added to the reaction.

[0037] As used herein, the term "liquid" refers to a material that is liquid at standard ambient temperature and pressure (SATP) (i.e., at a temperature of 298.15 K (25 °C) and at a pressure of 100000 Pa (1 bar, 14.5 psi, 0.9869 atm)).

[0038] As used herein, the term "hydrocarbon" refers to an organic compound composed of carbon and hydrogen.

[0039] To avoid doubt, hydrocarbons include straight-chain and branched, saturated and unsaturated aliphatic hydrocarbon compounds, including alkanes, alkenes, and alkynes; and saturated and unsaturated cyclic aliphatic hydrocarbon compounds, including cycloalkanes, cycloalkenes, and cycloalkynes; and hydrocarbon polymers, such as polyolefins.

[0040] Hydrocarbons also include aromatic hydrocarbons, i.e., hydrocarbons containing one or more aromatic rings. The aromatic ring can be monocyclic or polycyclic.

[0041] The term "hydrocarbon" (such compounds consisting only of carbon and hydrogen) of course also includes aliphatic hydrocarbons substituted by one or more aromatic hydrocarbons and aromatic hydrocarbons substituted by one or more aliphatic hydrocarbons, as well as straight-chain or branched aliphatic hydrocarbons substituted by one or more cyclic aliphatic hydrocarbons and cyclic aliphatic hydrocarbons substituted by one or more straight-chain or branched aliphatic hydrocarbons.

[0042] "C n-m hydrocarbon" or "Cn to C m "hydrocarbon" or "Cn to Cm hydrocarbon" (where n and m are integers) are hydrocarbons as defined above having from n to m carbon atoms. For example, C 5-16 hydrocarbons are hydrocarbons as defined above having from 5 to 16 carbon atoms, C 5+ hydrocarbons are hydrocarbons as defined above having 5 or more carbon atoms, and so on.

[0043] As used herein, the term "alkane" refers to linear or branched saturated hydrocarbon compounds. Examples of alkanes are, for example, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, and tetradecane. Alkanes such as dimethylbutane can be one or more of the possible isomers of the compound. Thus, dimethylbutane includes 2,3-dimethylbutane and 2,2-dimethylbutane. This also applies to all hydrocarbon compounds mentioned herein, including cycloalkanes, alkenes, cycloalkenes.

[0044] As used herein, the term "cycloalkane" refers to saturated cyclic aliphatic hydrocarbon compounds. Examples of cycloalkanes include cyclopropane, cyclobutane, cyclopentane, cyclohexane, methylcyclopentane, cycloheptane, methylcyclohexane, dimethylcyclopentane, and cyclooctane. Examples of C5-8 cycloalkanes include cyclopentane, cyclohexane, methylcyclopentane, cycloheptane, methylcyclohexane, dimethylcyclopentane, and cyclooctane. The terms "cycloalkane" and "cycloalkane" can be used interchangeably.

[0045] As used herein, the term "alkene" refers to linear or branched hydrocarbon compounds containing one or more carbon-carbon double bonds. Examples of alkenes are butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, tridecene, and tetradecene. Alkenes typically contain one or two double bonds. The terms "alkene" and "olefin" can be used interchangeably. One or more double bonds can be at any position in the hydrocarbon chain. Alkenes can be cis or trans alkenes (or defined using the E- and Z-nomenclature). Alkenes containing a terminal double bond can be referred to as "chain-1-ene" (e.g., hex-1-ene), "terminal alkene" (or "terminal olefin"), or "alpha-alkene" (or "alpha-olefin"). As used herein, the term "alkene" generally also includes cycloalkenes.

[0046] As used herein, the term "cycloalkene" refers to partially unsaturated cyclic hydrocarbon compounds. Examples of cycloalkenes include cyclobutene, cyclopentene, cyclohexene, cyclohex-1,3-diene, methylcyclopentene, cycloheptene, methylcyclohexene, dimethylcyclopentene, and cyclooctene. Cycloalkenes can contain one or two double bonds.

[0047] As used herein, the term "aromatic hydrocarbon" or "aromatic hydrocarbon compound" refers to a hydrocarbon compound containing one or more aromatic rings. The aromatic ring can be monocyclic or polycyclic. Generally, aromatic compounds contain benzene rings. Aromatic compounds can be, for example, C6-14 aromatic compounds, C6-12 aromatic compounds, or C6-10 aromatic compounds. Examples of C6-14 aromatic compounds are benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene, naphthalene, methylnaphthalene, ethylnaphthalene, and anthracene.

[0048] As used herein, "metal substance" is any compound containing a metal. Thus, metal substances include elemental metals, metal oxides, and other compounds containing metals, namely salts, alloys, hydroxides, carbides, borides, silicides, and hydrides of metals. When referring to specific examples of metal substances, the term includes all compounds containing that metal. For example, iron substances include, for example, elemental iron, iron oxides, iron salts, iron alloys, iron hydroxides, iron carbides, iron borides, iron silicides, and iron hydrides.

[0049] As used herein, the term "heterogeneous mixture" refers to a physical combination of at least two different substances, where the two different substances are not in the same phase. For example, one substance can be a solid and one substance can be a liquid or a gas.

[0050] Catalyst precursor

[0051] In one aspect, the present invention relates to a catalyst precursor comprising at least one iron substance, an alkali metal or its salt, and a complexing agent.

[0052] In one embodiment, the present invention relates to a catalyst precursor comprising iron or its salt, its oxide or its hydroxide, an alkali metal or its salt, and a complexing agent.

[0053] In one embodiment, the complexing agent is suitable for complexing metal cations (especially iron cations). Thus, suitable complexing agents contain one or more functional groups selected from carboxylic acid, hydroxyl, amide, or amino groups. Suitably, the complexing agent contains two or more functional groups selected from carboxylic acid, hydroxyl, amide, or amino groups. Suitably, the complexing agent is an organic compound.

[0054] In one embodiment, the complexing agent or organic compound is selected from hydroxycarboxylic acids, aminocarboxylic acids, polycarboxylic acids, or their salts. Suitably, the complexing agent or organic compound is selected from hydroxycarboxylic acids and polycarboxylic acids, or their salts. Alternatively, the complexing agent or organic compound is selected from hydroxycarboxylic acids and aminocarboxylic acids, or their salts.

[0055] In one embodiment, the complexing agent or organic compound is a bidentate or multidentate hydroxycarboxylic acid or its salt.

[0056] In one embodiment, the complexing agent or organic compound is selected from glycolic acid, lactic acid, hydracylic acid, hydroxybutyric acid, hydroxypentanoic acid, malic acid, mandelic acid, citric acid, saccharic acid, tartronic acid, tartaric acid, oxalic acid, malonic acid, maleic acid, tannic acid, succinic acid, salicylic acid, glutaric acid, adipic acid, glycine, hippuric acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitroilotiracetic acid, nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), alanine, valine, leucine and isoleucine, and salts thereof.

[0057] In one embodiment, the complexing agent or organic compound is selected from glycolic acid, lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxypentanoic acid, malic acid, mandelic acid, citric acid, saccharic acid, tartronic acid, tartaric acid, oxalic acid, malonic acid, maleic acid, tannic acid, succinic acid, salicylic acid, glutaric acid, adipic acid, hippuric acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or salts thereof.

[0058] In one embodiment, the complexing agent or organic compound is selected from hydroxybutyric acid, hydroxypentanoic acid, malic acid, mandelic acid, citric acid, saccharic acid, tartronic acid, tartaric acid, oxalic acid, malonic acid, maleic acid, tannic acid, succinic acid, salicylic acid, glutaric acid, adipic acid, hippuric acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or salts thereof.

[0059] In one embodiment, the complexing agent or organic compound is selected from hydroxybutyric acid, hydroxypentanoic acid, malic acid, mandelic acid, citric acid, saccharic acid, tartronic acid, tartaric acid, oxalic acid, malonic acid, maleic acid, tannic acid, succinic acid, salicylic acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or salts thereof.

[0060] In one embodiment, the complexing agent or organic compound is selected from citric acid, saccharic acid, tartaric acid, oxalic acid, salicylic acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or salts thereof.

[0061] In one embodiment, the complexing agent or organic compound is selected from citric acid, saccharic acid, tartaric acid, oxalic acid, salicylic acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or a salt thereof.

[0062] In one embodiment, the complexing agent or organic compound is selected from citric acid, tartaric acid, oxalic acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or a salt thereof. Suitably, the complexing agent is citric acid.

[0063] In one embodiment, the molar ratio of the complexing agent to the metal is from about 0.4:1 to about 4:1. Suitably, the molar ratio of the complexing agent to the metal is from about 0.5:1 to about 2:1.

[0064] In one embodiment, the molar ratio of the complexing agent to the metal is from about 0.8:1 to about 4:1. Suitably, the molar ratio of the complexing agent to the metal is from about 1:1 to about 3:1.

[0065] In one embodiment, the molar ratio of the complexing agent to the metal is from about 0.5:1 to about 5:1. Suitably, the molar ratio of the complexing agent to the metal is from about 0.8:1 to about 2:1.

[0066] In one embodiment, the molar ratio of the complexing agent to iron is from about 0.5:1 to about 5:1. Suitably, the molar ratio of the complexing agent to iron is from about 0.8:1 to about 2:1.

[0067] In one embodiment, the iron species is selected from elemental iron, iron salts, iron oxides, iron alloys, iron hydroxides, iron carbides, iron borides, iron silicides, and iron hydrides. Suitably, the iron species is selected from elemental iron, iron salts, iron alloys, iron hydroxides, and iron silicides. More suitably, the iron species is selected from elemental iron, iron salts, and iron hydroxides.

[0068] In one embodiment, the iron species is an iron salt. In one embodiment, the iron salt is iron nitrate, iron sulfate, an iron halide (suitably iron chloride), or an iron organic acid salt. Suitably, the iron salt is iron(III) nitrate or iron(II) nitrate.

[0069] In another embodiment, the iron species is iron powder. Those skilled in the art will understand that iron powder is elemental iron in a commercially available form.

[0070] In another embodiment, the iron species is an iron oxide, suitably Fe3O4.

[0071] In one embodiment, the catalyst precursor comprises from about 5 wt% to about 90 wt% of Fe. Suitably, the catalyst precursor comprises from about 10 wt% to about 90 wt% of Fe. Suitably, from about 15 wt% to about 90 wt% of Fe, more suitably from about 20 wt% to about 90 wt% of Fe, more suitably from about 25 wt% to about 90 wt% of Fe, more suitably from about 30 wt% to about 90 wt% of Fe, more suitably from about 40 wt% to about 90 wt% of Fe, more suitably from about 50 wt% to about 90 wt% of Fe.

[0072] In one embodiment, the catalyst precursor comprises from about 5 wt% to about 80 wt% of Fe. Suitably, the catalyst precursor comprises from about 10 wt% to about 80 wt% of Fe. Suitably, from about 15 wt% to about 80 wt% of Fe, more suitably from about 20 wt% to about 80 wt% of Fe, more suitably from about 25 wt% to about 80 wt% of Fe, more suitably from about 30 wt% to about 80 wt% of Fe, more suitably from about 40 wt% to about 80 wt% of Fe, more suitably from about 50 wt% to about 80 wt% of Fe.

[0073] In another embodiment, the catalyst precursor comprises from about 10 wt% to about 90 wt% of Fe. Suitably, the catalyst precursor comprises from about 10 wt% to about 80 wt% of Fe. Suitably, from about 10 wt% to about 70 wt% of Fe, more suitably from about 10 wt% to about 65 wt% of Fe.

[0074] In another embodiment, the catalyst precursor comprises from about 10 wt% to about 80 wt% of Fe. Suitably, the catalyst precursor comprises from about 10 wt% to about 70 wt% of Fe. Suitably, from about 10 wt% to about 60 wt% of Fe, more suitably from about 10 wt% to about 50 wt% of Fe.

[0075] In one embodiment, the alkali metal is selected from potassium, sodium, lithium or cesium. Thus, the catalyst precursor may comprise potassium, sodium, lithium or cesium, or a salt thereof. Suitably, the alkali metal is present as a salt. Suitably, the alkali metal is an alkali metal carbonate, such as potassium carbonate, sodium carbonate, cesium carbonate, lithium carbonate.

[0076] In one embodiment, the catalyst precursor comprises from about 0.5 wt% to about 30 wt% of the alkali metal. Suitably, the catalyst precursor comprises from about 0.5 wt% to about 25 wt% of the alkali metal. Suitably, from about 0.5 wt% to about 20 wt% of the alkali metal, more suitably from about 0.5 wt% to about 15 wt% of the alkali metal, more suitably from about 0.5 wt% to about 10 wt% of the alkali metal, more suitably from about 0.5 wt% to about 5 wt% of the alkali metal.

[0077] In one embodiment, the catalyst precursor comprises from about 1 wt% to about 30 wt% of an alkali metal. Suitably, the catalyst precursor comprises from about 1 wt% to about 25 wt% of an alkali metal. Suitably, from about 1 wt% to about 20 wt% of an alkali metal, more suitably from about 1 wt% to about 15 wt% of an alkali metal, more suitably from about 1 wt% to about 10 wt% of an alkali metal, more suitably from about 1 wt% to about 5 wt% of an alkali metal.

[0078] In one embodiment, the catalyst precursor may comprise additional metal substances. Suitably, these additional metals will be used as promoters in the catalytically active material. In one embodiment, the additional metal substance is a transition metal substance. Suitably, the additional metal substance is a transition metal, or its salt, its oxide or its hydroxide.

[0079] Suitably, the catalyst precursor further comprises cobalt, chromium, copper, iridium, manganese, molybdenum, palladium, platinum, rhenium, rhodium, ruthenium, strontium, tungsten, vanadium, zinc, or its salt, its oxide or its hydroxide.

[0080] In another embodiment, the catalyst precursor further comprises cobalt, copper, manganese, zinc, or its salt, its oxide or its hydroxide.

[0081] In one embodiment, the catalyst precursor comprises manganese oxide.

[0082] In one embodiment, the catalyst precursor comprises manganese nitrate.

[0083] In one embodiment, the catalyst precursor comprises from about 1 wt% to about 50 wt% of an additional metal substance. Suitably, the catalyst precursor comprises from about 1 wt% to about 40 wt% of an additional metal substance.

[0084] In another embodiment, the catalyst precursor comprises from about 5 wt% to about 30 wt% of an additional metal substance, more suitably from about 5 wt% to about 20 wt% of an additional metal substance, more suitably from about 5 wt% to about 15 wt% of an additional metal substance, more suitably from about 5 wt% to about 15 wt% of an additional metal substance.

[0085] In one embodiment, the catalyst precursor comprises from about 1 wt% to about 30 wt% of an additional metal substance. Suitably, the catalyst precursor comprises from about 1 wt% to about 25 wt% of an additional metal substance. Suitably, from about 1 wt% to about 20 wt% of an additional metal substance, more suitably from about 1 wt% to about 15 wt% of an additional metal substance, more suitably from about 1 wt% to about 10 wt% of an additional metal substance, more suitably from about 1 wt% to about 5 wt% of an additional metal substance.

[0086] In one embodiment, the catalyst precursor comprises iron or a salt, oxide or hydroxide thereof; at least one additional transition metal selected from Mn, Zn, Cu and Co, or a salt, oxide or hydroxide thereof; an alkali metal or a salt thereof; and a complexing agent.

[0087] In one embodiment, the catalyst precursor comprises iron or a salt, oxide or hydroxide thereof; at least one additional transition metal selected from Mn, Zn, Cu and Co, or a salt, oxide or hydroxide thereof; an alkali metal or a salt thereof; and an organic compound.

[0088] In another embodiment, the catalyst precursor comprises iron or a salt, oxide or hydroxide thereof; at least one additional transition metal or salt, oxide or hydroxide selected from Mn and Co; an alkali metal or a salt thereof; and a complexing agent.

[0089] In another embodiment, the catalyst precursor comprises iron or a salt, oxide or hydroxide thereof; at least one additional transition metal or salt, oxide or hydroxide selected from Mn and Co; an alkali metal or a salt thereof; and an organic compound.

[0090] In another embodiment, the catalyst precursor comprises iron or a salt, oxide or hydroxide thereof; an additional transition metal or salt, oxide or hydroxide selected from Mn and Co; an alkali metal or a salt thereof; and a complexing agent.

[0091] In another embodiment, the catalyst precursor comprises iron or a salt, oxide or hydroxide thereof; an additional transition metal or salt, oxide or hydroxide selected from Mn and Co; an alkali metal or a salt thereof; and an organic compound.

[0092] In another embodiment, the catalyst precursor comprises an iron salt, a manganese salt, an alkali metal or a salt thereof, and a complexing agent.

[0093] In another embodiment, the catalyst precursor comprises an iron salt, a manganese salt, an alkali metal or a salt thereof, and an organic compound.

[0094] In another embodiment, the catalyst precursor comprises iron powder, a manganese salt, a cobalt salt, an alkali metal or a salt thereof, and a complexing agent.

[0095] In another embodiment, the catalyst precursor comprises iron powder, a manganese salt, a cobalt salt, an alkali metal or a salt thereof, and an organic compound. In another embodiment, the catalyst precursor comprises iron nitrate, manganese nitrate, an alkali metal or a salt thereof, and a complexing agent.

[0096] In another embodiment, the catalyst precursor comprises iron nitrate, manganese nitrate, an alkali metal or a salt thereof, and an organic compound.

[0097] Suitably, the alkali metal is potassium. Thus, in one embodiment, the catalyst precursor comprises iron or a salt or an oxide thereof; at least one additional transition metal selected from Mn, Zn, Cu, and Co, or a salt or an oxide thereof; potassium or a salt thereof; and a complexing agent.

[0098] In another embodiment, the catalyst precursor comprises iron or a salt, an oxide, or a hydroxide thereof; at least one additional transition metal or a salt, an oxide, or a hydroxide thereof selected from Mn and Co; potassium or a salt thereof; and a complexing agent.

[0099] In another embodiment, the catalyst precursor comprises iron or a salt, an oxide, or a hydroxide thereof; at least one additional transition metal or a salt, an oxide, or a hydroxide thereof selected from Mn and Co; potassium or a salt thereof; and an organic compound.

[0100] Suitably, the complexing agent or the organic compound is defined as in one of the foregoing embodiments. Suitably, the cobalt salt is cobalt nitrate. Suitably, the manganese salt is manganese nitrate.

[0101] In one embodiment, the catalyst precursor comprises iron(II or III) nitrate, manganese(II) nitrate, potassium carbonate, and citric acid. In another embodiment, the catalyst precursor consists essentially of iron(II or III) nitrate, manganese(II) nitrate, potassium carbonate, and citric acid.

[0102] In another embodiment, the catalyst precursor comprises iron powder, manganese(II) nitrate, cobalt nitrate, sodium carbonate, and citric acid. In another embodiment, the catalyst precursor consists essentially of iron powder, manganese(II) nitrate, cobalt nitrate, sodium carbonate, and citric acid.

[0103] In one embodiment, the catalyst precursor comprises (i) Fe or a salt thereof, (ii) Mn or a salt thereof, (iii) K or a salt thereof, and (iv) citric acid or a salt thereof.

[0104] In one embodiment, the catalyst precursor comprises (i) Fe or a salt thereof, (ii) Mn or a salt thereof, (iii) Co or a salt thereof, (iii) K or a salt thereof, and (iv) citric acid or a salt thereof.

[0105] Suitably, the molar ratio of Fe:Mn is from about 100:1 to about 4:1, more suitably from about 15:1 to about 5:1.

[0106] Suitably, the molar ratio of Fe:K is from about 100:1 to about 2:1; more suitably, the molar ratio of Fe:K is from about 20:1 to about 4:1, more suitably from about 10:1 to about 2:1.

[0107] Suitably, the molar ratio of (Fe + Mn + K):citric acid is from about 5:1 to 0.5:1, suitably from about 2:1 to about 1:1.

[0108] Suitably, the molar ratio of Fe:Co is from about 40:1 to about 10:1, more suitably from about 30:1 to about 10:1, more suitably about 20:1.

[0109] Method for preparing a catalyst precursor

[0110] In a second aspect, the present invention relates to a method for preparing a catalyst precursor, which comprises:

[0111] (a) combining (i) at least one iron substance, (ii) an alkali metal or a salt thereof, (iii) a complexing agent, and (iv) a solvent;

[0112] (b) stirring the mixture of step (a) to provide a homogeneous mixture;

[0113] (c) heating the mixture of step (b) to partially remove the solvent, thereby providing a slurry or a paste.

[0114] In this aspect, the iron substance, the alkali metal or a salt thereof, and the complexing agent may be defined as in any of the foregoing embodiments.

[0115] In one embodiment, the solvent comprises water. Suitably, the solvent is water.

[0116] Step (a) may further comprise adding one or more additional metal substances, suitably additional transition metal substances. In one embodiment, an additional transition metal selected from Mn, Zn, Co, and Cu, or a salt, an oxide, or a hydroxide thereof is incorporated in step (a).

[0117] In step (b), the mixture may be stirred by any means known in the art such as stirring, shaking, vortexing, and sonication.

[0118] In step (c), the mixture is suitably heated to a temperature of about 30°C to 120°C, more suitably about 30°C to about 80°C, more suitably about 50°C.

[0119] The method may further comprise an additional step (d): wherein the slurry or paste of step (c) is calcined to provide a powder. Suitably, the calcination is carried out at a temperature of about 300°C to about 500°C, more suitably about 350°C. Suitably, the calcination is carried out in air, suitably in static air. Generally, the calcination will cause the combustion of the organic components of the precursor.

[0120] The method may further comprise step (e): wherein the calcined powder is, for example, ground or milled to reduce the particle size.

[0121] In another aspect, the present invention relates to a method for preparing a catalyst precursor, the method comprising:

[0122] (a) combining (i) iron powder, (ii) an alkali metal or its salt, and (iii) a complexing agent; and

[0123] (b) stirring the mixture of step (a) to provide a homogeneous mixture.

[0124] In one embodiment, step (a) may further include adding one or more additional metal substances. In one embodiment, at least one additional transition metal selected from Mn, Zn, Co, and Cu, or its salt, its oxide, or its hydroxide is incorporated in step (a). Suitably, Mn or its salt, its oxide, or its hydroxide and Co or its salt, its oxide, or its hydroxide are further incorporated in step (a).

[0125] In step (b), the stirring can be carried out by any means known in the art, such as stirring, shaking, milling, and grinding.

[0126] In one embodiment, the method for preparing a catalyst precursor comprises:

[0127] (a) combining: (i) iron powder; (ii) potassium, sodium, or lithium, or its salt; (iii) citric acid; and (iv) at least one additional transition metal selected from Mn and Co, or its salt, its oxide, or its hydroxide; and

[0128] (b) stirring the mixture of step (a) to provide a homogeneous mixture.

[0129] Catalyst and method for preparing the same

[0130] In another aspect, the present invention relates to a catalyst obtainable by activating a catalyst precursor obtainable according to the method described herein, or a catalyst obtainable by activating a catalyst precursor described herein.

[0131] Suitably, the catalyst is suitable for the hydrogenation of carbon dioxide and / or carbon monoxide.

[0132] In one embodiment, the catalyst comprises iron carbide, suitably Fe5C2.

[0133] In one embodiment, the catalyst comprises iron carbide; at least one additional transition metal selected from Mn, Zn, Cu, and Co, or its salt, its oxide, or its hydroxide; and an alkali metal or its salt.

[0134] In one embodiment, the catalyst comprises iron carbide; at least one additional transition metal or salt, oxide or hydroxide selected from Mn and Co; and an alkali metal or a salt thereof.

[0135] In another embodiment, the catalyst precursor comprises iron carbide; manganese or an oxide thereof; and an alkali metal.

[0136] In another embodiment, the catalyst comprises iron carbide; manganese or an oxide thereof; cobalt or an oxide thereof; and an alkali metal.

[0137] Suitably, the alkali metal is potassium.

[0138] In another embodiment, the catalyst comprises iron carbide; at least one additional transition metal or an oxide thereof selected from Mn and Co; and potassium.

[0139] Suitably, the iron carbide is Fe5C2.

[0140] Suitably, the molar ratio of Fe:Mn is from about 100:1 to about 4:1, more suitably from about 15:1 to about 5:1.

[0141] Suitably, the molar ratio of Fe:K is from about 100:1 to about 2:1; more suitably, the molar ratio of Fe:K is from about 20:1 to about 4:1, more suitably from about 10:1 to about 2:1.

[0142] Suitably, the molar ratio of Fe:Co is from about 40:1 to about 10:1, more suitably from about 30:1 to about 10:1, more suitably about 20:1.

[0143] In another aspect, the present invention relates to a method for preparing a catalyst, the method comprising:

[0144] (a) providing a catalyst precursor as defined in any of the above embodiments;

[0145] (b) optionally calcining the catalyst precursor; and

[0146] (c) activating the precursor.

[0147] In one embodiment, the catalyst is suitable for the hydrogenation of carbon dioxide and / or carbon monoxide.

[0148] Suitably, the calcination is carried out at a temperature of about 100 °C to about 500 °C, or about 250 °C to about 500 °C, more suitably about 300 °C to about 350 °C. Suitably, the calcination is carried out in air, suitably in static air. Generally, the calcination will result in the decomposition or partial combustion of the organic components of the precursor.

[0149] Step (b) may further comprise grinding or milling the calcined powder to reduce the particle size.

[0150] The calcined material of step (b) or the precursor of step (a) can be activated, for example, by reduction. Suitably, the material to be activated is exposed to a mixture of CO and hydrogen at a temperature of from about 250 °C to about 500 °C, more suitably from about 300 °C to about 350 °C.

[0151] Method for the hydrogenation of CO2 or CO

[0152] In one aspect, the present invention relates to a method for the hydrogenation of carbon dioxide, the method comprising: contacting a feedstock comprising hydrogen and carbon dioxide with a catalyst precursor or a catalyst as defined herein at elevated temperature and pressure.

[0153] In another aspect, the present invention relates to a method for the hydrogenation of carbon monoxide, the method comprising: contacting a feedstock comprising hydrogen and carbon monoxide with a catalyst precursor or a catalyst as defined herein at elevated temperature and pressure.

[0154] In another aspect, the present invention relates to a method for producing olefins, the method comprising: contacting a feedstock comprising (i) hydrogen and (ii) carbon dioxide and / or carbon monoxide with a catalyst precursor or a catalyst as defined herein at elevated temperature and pressure.

[0155] Suitably, the olefin is a C5+ olefin, or an α-olefin, or a linear olefin. More suitably, the olefin is a C5+ α-olefin. Suitably, the olefin is a linear α-olefin. More suitably, the olefin is a C5+ linear α-olefin.

[0156] Suitably, the olefin is a C 5-16 olefin. More suitably, the olefin is a C 5-16 α-olefin. More suitably, the olefin is a C 5-16 linear α-olefin.

[0157] In another aspect, the present invention relates to a method for producing hydrocarbons, the method comprising: contacting a feedstock comprising (i) hydrogen and (ii) carbon dioxide and / or carbon monoxide with a catalyst precursor or a catalyst as defined herein at elevated temperature and pressure.

[0158] Suitably, the hydrocarbon is a C5+ hydrocarbon, more suitably a C8 to C 18 hydrocarbon, more suitably a C8 to C 16 hydrocarbon. In one embodiment, the hydrocarbon is a C8 to C 18 alkane, more suitably a C8 to C 16 alkane. In one embodiment, the hydrocarbon is a hydrocarbon in the jet engine fuel range.

[0159] In another aspect, the present invention relates to a process for producing fuel, the process comprising contacting a feedstock comprising (i) hydrogen and (ii) carbon dioxide and / or carbon monoxide with a catalyst precursor or catalyst as defined herein at elevated temperature and pressure.

[0160] Suitably, the fuel is selected from gasoline, diesel and aviation / jet engine fuel.

[0161] In the case of carbon monoxide or carbon dioxide hydrogenation or olefin production, the catalyst or catalyst precursor is loaded into the reaction zone. The catalyst is activated ex-situ (e.g. by heating, or if desired, by oxidation and subsequent reduction with syngas or hydrogen). The catalyst precursor may be activated in-situ, for example, under the reaction conditions.

[0162] The catalyst can be used in a fixed bed, moving bed, ebullated bed, fluidized bed or slurry bed reactor. Suitably, the catalyst is used in a fixed bed reactor.

[0163] In one embodiment, when CO hydrogenation is desired, a feedstock comprising a mixture of hydrogen and carbon monoxide having a suitable H2:CO molar ratio is contacted with a catalyst bed and reacted under reaction conditions. Generally, the molar ratio of H2:CO ranges from about 0.4:1 to about 6:1, suitably from about 0.5:1 to about 3:1, more suitably from about 1:1 to about 2:1.

[0164] In another embodiment, when CO2 hydrogenation is desired, a feedstock comprising a mixture of hydrogen and carbon dioxide having a suitable H2:CO2 molar ratio is contacted with a catalyst bed and reacted under reaction conditions. Generally, the molar ratio of H2:CO2 ranges from about 0.4:1 to about 8:1, suitably from about 0.4:1 to about 6:1, suitably from about 0.5:1 to about 5:1, more suitably from about 1:1 to about 4:1. Suitably, the molar ratio of H2:CO2 ranges from about 0.5:1 to about 4:1, more suitably from about 1:1 to about 3:1.

[0165] The reaction temperature is elevated. As used herein, elevated temperature is a temperature elevated relative to standard ambient temperature (i.e. a temperature of 298.15 K (25 °C)). In one embodiment, the feedstock is contacted with the catalyst precursor or catalyst at a temperature of about 180 °C to about 500 °C, suitably about 250 °C to about 500 °C, more suitably about 280 °C to about 350 °C, or about 300 °C to about 350 °C.

[0166] The reaction pressure is increased. As used herein, an increased pressure is a pressure increased relative to standard ambient pressure (i.e., a pressure of 100,000 Pa (1 bar, 14.5 psi, 0.9869 atm)). In one embodiment, the feedstock is contacted with the catalyst precursor or catalyst at a pressure of from about 500 kPa to about 20 MPa, suitably from about 500 kPa to about 10 MPa, suitably from about 500 kPa to about 5 MPa, suitably from about 500 kPa to about 2 MPa, suitably about 1 MPa.

[0167] The present invention will now be further described by the following numbered paragraphs:

[0168] 1. A catalyst precursor comprising an iron substance (suitably iron or its salts, its oxides or its hydroxides), an alkali metal or its salt, and a complexing agent.

[0169] 2. The catalyst precursor according to paragraph 1, wherein the complexing agent comprises one or more functional groups selected from carboxylic acid, hydroxyl, amide or amino groups.

[0170] 3. The catalyst precursor according to paragraph 1, wherein the complexing agent comprises one or more functional groups selected from carboxylic acid, hydroxyl, and amide groups.

[0171] 4. The catalyst precursor according to paragraph 1, wherein the complexing agent is selected from hydroxycarboxylic acids, aminocarboxylic acids and polycarboxylic acids, or their salts.

[0172] 5. The catalyst precursor according to paragraph 1, wherein the complexing agent is selected from glycolic acid, lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxypentanoic acid, malic acid, mandelic acid, citric acid, saccharic acid, tartronic acid, tartaric acid, oxalic acid, malonic acid, maleic acid, tannic acid, succinic acid, salicylic acid, glutaric acid, adipic acid, glycine, hippuric acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), alanine, valine, leucine and isoleucine, and their salts.

[0173] 6. The catalyst precursor according to paragraph 1, wherein the complexing agent is selected from citric acid, tartaric acid, oxalic acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or their salts.

[0174] 7. The catalyst precursor according to any one of the preceding paragraphs, wherein the complexing agent is citric acid and / or its salt.

[0175] 8. The catalyst precursor according to any one of the preceding paragraphs, wherein the alkali metal is selected from potassium, sodium, lithium, and cesium.

[0176] 9. The catalyst precursor according to any one of the preceding paragraphs, wherein the alkali metal is selected from potassium, sodium, and cesium.

[0177] 10. The catalyst precursor according to any one of the preceding paragraphs, wherein the alkali metal is potassium.

[0178] 11. The catalyst precursor according to any one of the preceding paragraphs, wherein the iron substance is iron nitrate, suitably iron(II) nitrate or iron(III) nitrate.

[0179] 12. The catalyst precursor according to any one of paragraphs 1 to 10, wherein the iron substance is selected from elemental iron, iron oxides, iron salts, or iron hydroxides, suitably, wherein the iron substance is iron powder.

[0180] 13. The catalyst precursor according to any one of the preceding paragraphs, comprising an additional metal substance.

[0181] 14. The catalyst precursor according to paragraph 13, wherein the additional metal substance is present in an amount of about 1 wt% to about 20 wt%.

[0182] 15. The catalyst precursor according to any one of the preceding paragraphs, further comprising one or more transition metals selected from Mn, Zn, Co, and Cu, or salts, oxides, or hydroxides thereof.

[0183] 16. The catalyst precursor according to paragraph 15, wherein the transition metals are selected from Mn and Co, or salts, oxides, or hydroxides thereof.

[0184] 17. The catalyst precursor according to any one of the preceding paragraphs, comprising (i) Fe or a salt thereof, (ii) Mn or a salt thereof, (iii) K or a salt thereof, and (iv) citric acid or a salt thereof.

[0185] 18. The catalyst precursor according to paragraph 17, further comprising (v) Co or a salt thereof.

[0186] 19. The catalyst precursor according to any one of paragraphs 1 to 11 and 13 to 17, comprising iron(III) nitrate, manganese(II) nitrate, potassium carbonate, and citric acid.

[0187] 20. The catalyst precursor according to any one of paragraphs 1 to 10 and 12 to 18, comprising iron powder, manganese(II) nitrate, cobalt nitrate, sodium carbonate, and citric acid.

[0188] 21. The catalyst precursor according to any one of the preceding paragraphs, wherein the molar ratio of Fe:alkali metal is from about 100:1 to about 4:1, suitably from about 20:1 to about 4:1, more suitably about 10:1.

[0189] 22. The catalyst precursor according to any one of the preceding paragraphs, wherein the molar ratio of the complexing agent to Fe is from about 1:1 to about 3:1.

[0190] 23. The catalyst precursor according to any one of paragraphs 15 to 20, wherein the molar ratio of Fe:Mn is from about 100:1 to about 4:1, suitably about 10:1.

[0191] 24. The catalyst precursor according to any one of paragraphs 15 to 20, wherein the molar ratio of (Fe + Mn + K):citric acid is from about 5:1 to about 0.5:1, suitably from about 2:1 to about 1:1.

[0192] 25. The catalyst precursor according to any one of paragraphs 15, 16, 18 and 20, wherein the molar ratio of Fe:Co is from about 40:1 to about 10:1, more suitably from about 30:1 to about 10:1, more suitably about 20:1.

[0193] 26. A method for preparing a catalyst precursor, comprising:

[0194] (a) combining (i) an iron substance (suitably iron or its salt, its oxide or its hydroxide), (ii) an alkali metal or its salt, (iii) a complexing agent, and (iv) a solvent;

[0195] (b) stirring the mixture of step (a) to provide a homogeneous mixture;

[0196] (c) heating the mixture of step (b) to partially remove the solvent, thereby providing a slurry or paste.

[0197] 27. The method according to paragraph 26, wherein step (a) further comprises incorporating one or more transition metals selected from Mn, Zn, Co and Cu, or their salts, their oxides or their hydroxides.

[0198] 28. The method according to any one of paragraphs 26 to 27, wherein step (a) comprises combining (i) Fe or its salt, (ii) Mn or its salt, (iii) K or its salt, and (iv) citric acid or its salt.

[0199] 29. The method according to any one of paragraphs 26 to 28, wherein the iron substance in step (a) is iron(III) nitrate.

[0200] 30. A method according to any one of paragraphs 26 to 29, wherein step (a) comprises combining iron(III) nitrate, manganese(II) nitrate, potassium carbonate and citric acid.

[0201] 31. A method according to any one of paragraphs 26 to 30, wherein step (a) comprises combining iron(III) nitrate, manganese(II) nitrate, potassium carbonate and citric acid with water.

[0202] 32. A method according to paragraph 28, wherein the weight ratio of (i) to (iv) in step (a) to the solvent is from about 3:1 to about 1:3, suitably about 2:1.

[0203] 33. A method according to any one of paragraphs 26 to 32, further comprising (d): calcining the paste or slurry of step (c) to provide a powder.

[0204] 34. A method according to paragraph 33, wherein the calcination is carried out at a temperature of from about 100 °C to about 500 °C, suitably from about 250 °C to about 500 °C, suitably from about 300 °C to about 350 °C.

[0205] 35. A method according to any one of paragraphs 33 and 34, wherein the calcination is carried out in air or an inert atmosphere, suitably in static air.

[0206] 36. A method according to any one of paragraphs 33 to 35, further comprising (e): grinding the powder of step (d).

[0207] 37. A method for preparing a catalyst precursor, comprising:

[0208] (a) combining (i) iron powder, (ii) an alkali metal or its salt, (iii) a complexing agent; and

[0209] (b) stirring the mixture of step (a) to provide a homogeneous mixture.

[0210] 38. A method according to paragraph 37, wherein step (a) further comprises adding one or more additional metal substances.

[0211] 39. A method according to any one of paragraphs 37 and 38, wherein step (a) further comprises incorporating Mn or its salt, its oxide or its hydroxide and Co or its salt, its oxide or its hydroxide.

[0212] 40. The method according to claim 37, comprising:

[0213] (a) Combine the following: (i) iron powder; (ii) potassium, sodium or lithium, or a salt thereof; (iii) citric acid; and (iv) at least one additional transition metal selected from Mn and Co, or a salt, an oxide or a hydroxide thereof; and

[0214] (b) Stir the mixture of step (a) to provide a homogeneous mixture.

[0215] 41. A method according to any one of paragraphs 27 to 36 and paragraphs 38 to 40, wherein the molar ratio of Fe:Mn in step (a) is from about 100:1 to about 4:1, suitably about 10:1.

[0216] 42. A method according to any one of paragraphs 26 to 41, wherein the molar ratio of Fe:alkali metal in step (a) is from about 100:1 to about 4:1, suitably from about 20:1 to about 4:1.

[0217] 43. A method according to any one of paragraphs 28, 30 to 32, wherein the molar ratio of Fe:K in step (a) is about 10:1.

[0218] 44. A method according to paragraph 28, wherein the molar ratio of (Fe + Mn + K):citric acid in step (a) is from about 5:1 to 0.5:1, suitably from about 2:1 to about 1:1.

[0219] 45. A method according to any one of paragraphs 26 to 44, wherein the molar ratio of the complexing agent to Fe is from about 1:1 to about 3:1.

[0220] 46. A method according to any one of paragraphs 26 to 36, wherein step (c) comprises heating the mixture to about 30 °C to 80 °C, suitably about 50 °C.

[0221] 47. A method according to any one of paragraphs 26 and 37, wherein the complexing agent is as described in any one of paragraphs 2 to 7.

[0222] 48. A method according to any one of paragraphs 26 and 37, wherein the alkali metal is as described in any one of paragraphs 8 to 10.

[0223] 49. A method according to paragraph 40, wherein step (a) comprises combining iron powder, manganese(II) nitrate, cobalt nitrate, sodium carbonate and citric acid.

[0224] 50. A catalyst obtainable by activating a catalyst precursor as defined in paragraphs 1 to 25, or obtainable by activating a catalyst precursor obtainable by a method according to any one of paragraphs 26 to 49.

[0225] 51. A method for preparing a catalyst, comprising:

[0226] (a) providing a catalyst precursor as described in any one of paragraphs 1 to 25;

[0227] (b) optionally calcining the catalyst precursor; and

[0228] (c) activating the precursor.

[0229] 52. The method according to paragraph 51, wherein the calcination is carried out at a temperature of about 100 °C to about 500 °C, about 250 °C to about 500 °C, suitably about 300 °C to about 350 °C.

[0230] 53. The method according to any one of paragraphs 51 and 52, wherein the calcination is carried out in air or an inert atmosphere, suitably in static air.

[0231] 54. The method according to any one of paragraphs 51 to 53, wherein step (c) comprises reducing the precursor, suitably by exposure to CO and hydrogen.

[0232] 55. The method according to any one of paragraphs 51 to 54, further comprising (d): grinding or granulating the product of step (c).

[0233] 56. A catalyst obtainable by the method according to any one of paragraphs 51 to 55.

[0234] 57. A catalyst for the hydrogenation of carbon dioxide and / or carbon monoxide, the catalyst comprising an iron material, manganese or its oxide, cobalt or its oxide, an alkali metal, and optionally at least one selected from zinc and copper.

[0235] 58. The catalyst according to paragraph 57, the catalyst comprising iron carbide, manganese or its oxide, cobalt or its oxide, and an alkali metal.

[0236] 59. The catalyst according to any one of paragraphs 57 - 58, the alkali metal being potassium.

[0237] 60. The catalyst according to any one of paragraphs 57 - 59, the molar ratio of Fe:Mn being from 100:1 to 4:1.

[0238] 61. The catalyst according to any one of paragraphs 57 - 60, the molar ratio of Fe:Mn being from 15:1 to 5:1.

[0239] 62. The catalyst according to any one of paragraphs 57 - 61, the molar ratio of Fe:alkali metal being from 100:1 to 2:1.

[0240] 63. The catalyst according to any one of paragraphs 57 - 62, wherein the molar ratio of Fe:alkali metal is from 20:1 to 4:1.

[0241] 64. The catalyst according to any one of paragraphs 57 - 63, wherein the iron carbide is Fe5C2.

[0242] 65. A method for the hydrogenation of carbon dioxide, comprising: contacting a feedstock comprising hydrogen and carbon dioxide with a catalyst precursor according to paragraphs 1 to 25 or a catalyst according to any one of paragraphs 50 and 56 at elevated temperature and pressure.

[0243] 66. The method according to paragraph 65, wherein the catalyst precursor is the catalyst precursor according to paragraphs 11, 17 and 19.

[0244] 67. The method according to any one of paragraphs 65 and 66, wherein the molar ratio of hydrogen to carbon dioxide in the feedstock is from 0.4:1 to 6:1, suitably about 1:1 to about 3:1.

[0245] 68. A method for the hydrogenation of carbon monoxide, comprising: contacting a feedstock comprising hydrogen and carbon monoxide with a catalyst precursor according to paragraphs 1 to 25 or a catalyst according to any one of paragraphs 50 and 56 at elevated temperature and pressure.

[0246] 69. The method according to paragraph 68, wherein the catalyst precursor is the catalyst precursor according to paragraphs 12, 15 to 18 and 20.

[0247] 70. The method according to any one of paragraphs 68 and 69, wherein the molar ratio of hydrogen to carbon monoxide in the feedstock is from 0.4:1 to 6:1, suitably about 1:1 to about 2:1.

[0248] 71. A method for producing hydrocarbons, especially olefins, comprising: contacting a feedstock comprising hydrogen and carbon monoxide, or hydrogen and carbon dioxide with a catalyst precursor according to paragraphs 1 to 25 or a catalyst according to any one of paragraphs 50 and 56 at elevated temperature and pressure.

[0249] 72. The method according to paragraph 71, wherein the molar ratio of H2:CO2 or H2:CO in the feedstock is from 0.4:1 to 6:1.

[0250] 73. The method according to any one of paragraphs 71 and 72, wherein the hydrocarbon is C 5+ hydrocarbon and the olefin is C 5+ olefin, suitably C 5+ α - olefin.

[0251] 74. The method according to paragraph 73, wherein C5+ The olefin is C 5-16 The olefin or C 5-16 α-olefin.

[0252] 75. A method according to any one of paragraphs 65 to 73, wherein the feedstock is contacted with the catalyst precursor or the catalyst at a temperature of from about 100 °C to about 500 °C, suitably from about 250 °C to about 500 °C, suitably from about 300 °C to about 350 °C.

[0253] 76. A method according to any one of paragraphs 65 to 75, wherein the feedstock is contacted with the catalyst precursor or the catalyst at a pressure of from about 500 KPa to about 2 Mpa, suitably about 1 MPa.

[0254] 77. A method according to any one of paragraphs 65 to 76, wherein the feedstock is contacted with the catalyst precursor or the catalyst at a GHSV (gas hourly space velocity) of from about 100 hours -1 to about 20,000 hours -1 , suitably from about 1000 hours -1 to about 5000 hours -1 .

[0255] 78. A heterogeneous mixture comprising a catalyst precursor according to any one of paragraphs 1 to 25 or a catalyst according to any one of paragraphs 50 and 56, and a gas containing hydrogen and carbon monoxide, or hydrogen and carbon dioxide.

[0256] Embodiment

[0257] 1. CO2 hydrogenation

[0258] All catalyst component materials were obtained from the commercial sources shown below and used without further modification.

[0259] The general method for preparing the catalyst employs the organic combustion method. Generally, an iron salt and an alkali metal salt are mixed with a complexing agent in a desired ratio and stirred in water to provide a homogeneous aqueous solution. The solution is heated at about 50 °C for 1 hour to 2 hours to obtain a slurry. Then the slurry is calcined in a furnace at about 350 °C in static air for 4 hours to provide the catalyst precursor.

[0260] For example, the preparation of the Fe-Mn-K catalyst involves mixing citric acid monohydrate with iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate, where the molar ratio of citric acid:(Fe + Mn + K) is about 2, and the weight ratio of (Fe precursor and Mn precursor and K precursor + citric acid) / water is about 2:1. The mixture is stirred to form a homogeneous aqueous solution and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste is calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0261] The carbon dioxide hydrogenation experiment was carried out in a fixed bed reactor ( Figure 1 ). Generally, 1.0 g of the catalyst precursor was mixed with 4.0 g of silicon carbide and loaded into the reactor. Before the reaction, the catalyst precursor was reduced in syngas (H2:CO = 2:1) at atmospheric pressure with a GHSV (gas hourly space velocity) of 1000 mL / g h for 24 hours at 320 °C with a heating rate of 2 °C / min to provide an activated catalyst.

[0262] After reduction, the temperature was lowered to about 50 °C, and a mixture of H2 / CO2 (3:1) and N2 (as an internal standard) was used as the feed gas. The gas flow rate was set at 40 mL / min (GSVH = 2400 mL / g catalyst). N2 was added as an inert gas to the syngas feed for conversion calculation. Since the mass flow rate of N2 did not change before and after the reaction, the CO2 and H2 conversion rates, CO and C n H m selectivity can be calculated as described below.

[0263] The reactor was heated at a rate of 2 °C / min until the reaction temperature (about 300 °C to 320 °C). The reaction pressure was controlled at 10 bar (1 Mpa) by a back pressure regulator.

[0264] The gas products were analyzed on a Perkin Elmer Clarus GC, and the collected liquid products were analyzed by GC-MS.

[0265] The conversion rates of CO2 and H2 and the product selectivities were calculated by the following equations:

[0266]

[0267] Table 1 provides examples of Fe-Mn-K catalysts with different Fe:Mn:K ratios prepared as described above using citric acid as a complexing agent. After a reaction time of 20 hours as described above, the conversion rates of H2 and CO2 and the product selectivities for different catalysts are shown in Table 1.

[0268] Table 1

[0269]

[0270] Table 2 and Figure 2 provides the molar ratio of olefins to paraffins of the produced C2 to C4 hydrocarbons.

[0271] Table 2

[0272]

[0273] Table 2 and Figure 2 shows that in the liquid product, the catalyst shows higher selectivity for olefins relative to paraffins. The GC-MS spectrum of the liquid product shows that the products are concentrated in C6 to C 16 hydrocarbons, and the main peak is attributed to linear α-olefins.

[0274] The XRD patterns of each catalyst were recorded on a Bruker D8 ECO X-ray diffractometer using graphite-monochromated Cu Kα radiation (λ = 0.15418 nm, in the 2θ range of 20° to 80°, at a scanning rate of 0.02° / s). Most of the peaks can be attributed to Fe3O4.

[0275] Based on the peak at 2θ = 35.9°, the crystallite size was calculated using the Debye-Scherrer formula:

[0276]

[0277] where β is the full width at half maximum (FWHM) value of the XRD diffraction line, the wavelength λ = 0.15418 nm, and θ is half of the diffraction angle 2θ. The catalyst shows a small crystallite size of about 10 nm (Table 3), which is consistent with the broad peaks in the XRD spectrum ( Figure 3 ).

[0278] Table 3

[0279]

[0280] To study the effect of various promoters on CO2 hydrogenation, iron-based catalysts were prepared with potassium and various promoters. The catalysts were prepared using an organic combustion method similar to the above-mentioned organic combustion method with citric acid as a complexing agent. The catalyst precursors of the catalysts studied in Table 4 were prepared as follows:

[0281] Example 4: Citric acid monohydrate and iron(III) nitrate nonahydrate in a molar ratio of 2:1 were dissolved in water to form a homogeneous aqueous solution (the weight ratio of (iron(III) nitrate nonahydrate + citric acid monohydrate) to water was about 2:1), and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0282] Example 5: Citric acid monohydrate, iron(III) nitrate nonahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:K was 100:10, the molar ratio of citric acid:(Fe + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + potassium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0283] Example 6: Citric acid monohydrate, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of citric acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0284] Example 7: Citric acid monohydrate, iron(III) nitrate nonahydrate, zinc nitrate hexahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:Zn:K was 100:10:10, the molar ratio of citric acid:(Fe + Zn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + zinc nitrate hexahydrate + potassium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0285] Example 8: Citric acid monohydrate, iron(III) nitrate nonahydrate, copper(II) nitrate trihydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Cu:K was 100:10:10, the molar ratio of citric acid:(Fe + Cu + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + copper(II) nitrate trihydrate + potassium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 h to 2 h to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 h to produce a catalyst powder.

[0286] The catalyst performance was evaluated in the CO2 hydrogenation as described above with a reaction time of 20 h.

[0287] Table 4 shows the effect of including a transition metal (TM) promoter in the catalyst. Catalysts were prepared using citric acid as a complexing agent and having a molar ratio of K:Fe and TM:Fe of 1:10 where applicable. In Table 4, the column headings for hydrocarbons have the following meanings: C 2-4 =: C2 - C4 olefins, C 2-4 0: C2 - C4 alkanes; C 5+ : liquid products; C 5-16 =: C5 - C 16 olefins.

[0288] Table 4

[0289]

[0290] Table 5 provides the molar ratio of olefins:alkanes for the C2 - C4 hydrocarbons produced.

[0291] Table 5

[0292]

[0293] The XRD patterns of each catalyst were recorded on a Bruker D8 ECO X-ray diffractometer using graphite-monochromated Cu Kα radiation (λ = 0.15418 nm, in the 2θ range of 10° to 90°, at a scan rate of 0.02° / s) Figure 4 ), and the crystallite size was calculated using the Debye-Scherrer formula as described above. The catalysts showed different crystallite sizes (Table 6).

[0294] Table 6

[0295]

[0296] To study the effect of various alkali metals on the hydrogenation of CO2, iron-based catalysts were prepared with a manganese promoter and an alkali metal varied between Na, K, and Cs. The catalysts were prepared using an organic combustion method similar to the above-mentioned organic combustion method. The catalyst precursors of the catalysts studied in Table 7 were prepared as follows:

[0297] Example 9: Citric acid monohydrate, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:Mn:Na was 100:10:10, the molar ratio of citric acid:(Fe + Mn + Na) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + sodium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0298] Example 10: Citric acid monohydrate, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of citric acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a catalyst powder.

[0299] Example 11: Citric acid monohydrate, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and cesium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:Mn:Cs was 100:10:10, the molar ratio of citric acid:(Fe + Mn + Cs) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + cesium carbonate + citric acid) / water was about 2:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0300] The catalyst performance was evaluated in the CO2 hydrogenation as described above with a reaction time of 20 hours.

[0301] Table 7 shows the effect of including an alkali metal (AM) in the catalyst. The catalysts were prepared using citric acid as a complexing agent, and the catalysts had a molar ratio of AM:Fe and Mn:Fe of 1:10. In Table 7, the column headings for hydrocarbons have the following meanings: C 2-4=: C2 to C4 olefins, C 2-4 0: C2 to C4 alkanes; C 5+ : Liquid product; C 5-16 =: C5 to C 16 olefins.

[0302] Table 7

[0303]

[0304] Table 8 provides the olefin:alkane molar ratio of the C2 to C4 hydrocarbons produced.

[0305] Table 8

[0306]

[0307] The XRD patterns of each catalyst were recorded on a Bruker D8 ECO X-ray diffractometer using graphite-monochromated Cu Kα radiation (λ = 0.15418 nm, in the 2θ range from 10° to 90°, at a scanning rate of 0.02° / s) Figure 5 ), and the crystallite sizes were calculated using the Debye-Scherrer formula as described above. The catalysts showed different crystallite sizes (Table 9).

[0308] Table 9

[0309]

[0310] To study the effect of the complexing agents used in the preparation of the catalysts on the catalyst performance, a series of iron-based catalysts were prepared using various complexing agents. The catalysts contained potassium and manganese in a molar ratio of 1:10 relative to Fe. The catalysts were prepared using an organic combustion method similar to the above-described organic combustion method. The catalyst precursors of the catalysts studied in Table 10 were prepared as follows:

[0311] Example 12 (reference): Iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution, where the molar ratio of Fe:Mn:K was 100:10:10, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate) / water was approximately 2:1. The mixture was stirred and heated at 50 °C for 1 hour to 2 hours to obtain an anhydrous mixture. The mixture was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0312] Example 13: Urea, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of urea:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + urea) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a urea-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0313] Example 14: Tannic acid, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of tannic acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + tannic acid) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a tannic acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0314] Example 15: Ethylenediaminetetraacetic acid (EDTA), iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of EDTA:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + EDTA) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain an EDTA-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0315] Example 16: Citric acid, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of citric acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + citric acid) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a catalyst powder.

[0316] Example 17: Glycine, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of glycine:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + glycine) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a glycine-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0317] Example 18: Oxalic acid, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of oxalic acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + oxalic acid) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain an oxalic acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0318] Example 19: Nitrilotriacetic acid (NTA), iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of NTA:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + NTA) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain an NTA-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0319] Example 20: Diethylenetriaminepentaacetic acid (DTPA), iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of DTPA:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + DTPA) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a DTPA-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0320] Example 21: Tartaric acid, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of tartaric acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + tartaric acid) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a tartaric acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0321] Example 22: Hydroxyethylenediaminetriacetic acid (HEDTA), iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of HEDTA:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + HEDTA) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain an HEDTA-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0322] Example 23: Salicylic acid, iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of salicylic acid:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + salicylic acid) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a salicylic acid-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0323] Example 24: Sugar (commercial granulated sugar), iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous solution in which the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of sugar:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + sugar) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a sugar-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0324] Example 25: Flour (commercial white wheat flour (plain flour or self-raising flour)), iron(III) nitrate nonahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were dissolved in water to form a homogeneous aqueous slurry, where the molar ratio of Fe:Mn:K was 100:10:10, the molar ratio of flour:(Fe + Mn + K) was about 2, and the weight ratio of (iron(III) nitrate nonahydrate + manganese(II) nitrate tetrahydrate + potassium carbonate + flour) / water was about 1:1. The mixture was stirred and heated at 50 °C for 1 to 2 hours to obtain a flour-based slurry. The paste was calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0325] The catalyst performance was evaluated in the CO2 hydrogenation as described above with a reaction time of 20 hours.

[0326] Table 10 shows the effect of the complexing agent used in the preparation of the catalyst on the performance. In Table 10, the column headings for hydrocarbons have the following meanings: C 2-4 =: C2 to C4 olefins, C 2-4 0: C2 to C4 alkanes; C 5+ : liquid products; C 5-16 =: C5 to C 16 olefins.

[0327] Table 10

[0328]

[0329] Table 11 provides the molar ratio of olefins to alkanes of the produced C2 to C4 hydrocarbons.

[0330] Table 11

[0331]

[0332] The XRD patterns of each catalyst were recorded on a Bruker D8 ECO X-ray diffractometer using graphite-monochromated Cu Kα radiation (λ = 0.15418 nm, in the 2θ range from 10° to 90°, at a scanning rate of 0.02° / s) Figure 6 and 7 ), and the crystallite size was calculated using the Debye-Scherrer formula as described above. The catalysts showed different crystallite sizes (Table 12).

[0333] Table 12

[0334]

[0335] Iron-based catalysts prepared with complexing agents and addition of Na, K, and / or Cs improve the selectivity for olefin production in the CO2 hydrogenation reaction. Further addition of Mn, Zn, and / or Cu promoters also shows high selectivity for olefins relative to alkanes. Different organic compounds are applied as complexing agents during catalyst preparation. Catalysts prepared with citric acid, EDTA, oxalic acid, NTA, DTPA, tartaric acid, HEDTA show the highest selectivity for olefins. The catalysts can also be used to produce fuels (gasoline, diesel, aviation fuel / jet engine fuel) via hydrogenation of CO2 and / or CO.

[0336] 2. CO hydrogenation

[0337] All catalyst component materials are obtained from the commercial sources shown below and used without further modification.

[0338] Typically, iron powder is used as the iron source to prepare the catalyst. Iron powder, cobalt nitrate, manganese nitrate, alkali metal salts (such as potassium carbonate, sodium carbonate, lithium carbonate, cesium carbonate) are mixed together, the mixture is ground homogeneously, the complexing agent (citric acid) is added (appropriately at a weight ratio of about 1:1 to iron) to the mixture, and the mixture is ground homogeneously again. The obtained mixture is dried at 80 °C for 24 hours. The dried mixture (uncalcined) is ground into a powder to provide a catalyst precursor.

[0339] Before the reaction, the catalyst precursor is reduced in syngas (H2:CO = 2:1 or 1:1) at atmospheric pressure, where the GHSV (gas hourly space velocity) is 1000 mL / g h, at 320 °C for 32 hours, with a heating rate of 5 °C / min to provide an activated catalyst.

[0340] After reduction, the temperature is lowered to less than 50 °C, and a mixture of H2 / CO (1:1) and N2 (as an internal standard) is used as the feed gas. The gas flow rate is set to 40 mL / min (GSVH = 2400 mL / g catalyst). N2 is added as an inert gas to the syngas feed for conversion calculation. Since the mass flow rate of N2 does not change before and after the reaction, the CO and H2 conversions, CO2 and C n H m selectivities can be calculated as described below.

[0341] The reactor ( Figure 1 ) is heated at a rate of 2 °C / min until the reaction temperature (about 280 °C to 320 °C). The reaction pressure is controlled at 10 bar (1 Mpa) by a back pressure regulator.

[0342] The gas products are analyzed on a Perkin Elmer Clarus GC, and the collected liquid products are analyzed by GC-MS.

[0343] The conversion rates of CO and H2 and the product selectivity are calculated by the following equations:

[0344]

[0345] Table 13 studied the effect of adding an additional transition metal cobalt to the Fe-Mn-Na catalyst. After the reaction as described above, for different catalysts, the reaction time, the conversion rates of H2 and CO, and the product selectivity are shown in Table 13.

[0346] The catalyst precursors of the catalysts studied in Table 13 were prepared as follows:

[0347] Examples 26 to 30: Iron powder, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Mn:Na of 100:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 4:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into powder.

[0348] Examples 31 to 35: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 10:2:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 4:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into powder.

[0349] Examples 36 to 44: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:5:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 4:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into powder.

[0350] Examples 45 to 50: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:8:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 4:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into powder.

[0351] Examples 51 to 55: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:10:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 4:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a powder.

[0352] Table 13

[0353]

[0354] Table 14 provides the molar ratio of olefins to alkanes of the produced C2 to C4 hydrocarbons.

[0355] Table 14

[0356]

[0357] Table 15 investigated the effects of various alkali metals on CO hydrogenation. Iron-based catalysts were prepared with manganese and cobalt promoters and an alkali metal varied between Na, K, and Li. The catalysts were prepared using a method similar to the above method. The catalyst precursors of the catalysts studied in Table 15 were prepared as follows:

[0358] Examples 56 to 65: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and lithium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Li of 100:5:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 1:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a powder.

[0359] Examples 66 to 70: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:5:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 1:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a powder.

[0360] Examples 71 to 76: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and potassium carbonate were mixed together in a molar ratio of Fe:Co:Mn:K of 100:5:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 1:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a powder.

[0361] Table 15

[0362]

[0363] Table 16 provides the molar ratio of olefins to alkanes of the produced C2 to C4 hydrocarbons.

[0364] Table 16

[0365]

[0366] Table 17 investigated the effect of manganese loading on CO hydrogenation. Iron-based catalysts were prepared using manganese and cobalt promoters and sodium. Catalysts were prepared using a method similar to the above method. In particular, the precursors of the catalysts in Table 17 were prepared as follows:

[0367] Examples 76 to 80: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:5:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 1:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a powder.

[0368] Examples 81 to 88: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:5:20:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 1:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a catalyst powder.

[0369] Table 17

[0370]

[0371] Table 18 provides the molar ratio of olefins to alkanes of the produced C2 to C4 hydrocarbons.

[0372] Table 18

[0373]

[0374] Table 19 studied the effect of feedstock composition on the hydrogenation of CO. Iron-based catalysts were prepared using manganese and cobalt promoters and sodium. The catalysts were prepared using a method similar to the above method. Synthesis gas with different ratios of H2:CO was used for the reaction.

[0375] The precursors of the catalysts in Table 19 were prepared as follows:

[0376] Examples 89 to 110: Iron powder, cobalt(II) nitrate hexahydrate, manganese(II) nitrate tetrahydrate, and sodium carbonate were mixed together in a molar ratio of Fe:Co:Mn:Na of 100:5:10:2. The mixture was ground evenly. Citric acid was added to the mixture, and the mixture was ground evenly again, where the weight ratio of citric acid to iron powder was 4:1. The obtained mixture was dried at 80 °C for 24 hours. The dried mixture (uncalcined) was ground into a powder.

[0377] Table 19

[0378]

[0379] Table 20 provides the molar ratio of olefins to paraffins of the C2 to C4 hydrocarbons produced.

[0380] Table 20

[0381]

[0382] Tables 21 and 22 studied the hydrogenation of CO using an Fe-Co-Mn-Na catalyst (100:5:20:2) under various conditions. The GC-MS spectrum of the product curve of Example 111 is shown in Figure 8 in.

[0383] Table 21

[0384]

[0385] Table 22

[0386]

[0387] Iron powder was used as the iron source together with a complexing agent for the preparation of the catalyst. The preparation did not require calcination, thus saving energy and reducing emissions. The prepared catalyst exhibited high CO conversion, low CH4 selectivity, high olefin selectivity, and stability. The addition of an alkali metal and an optional transition metal (such as Co, Mn) improved the olefin selectivity in the gas and liquid products. In the case of a relatively high H2:CO molar ratio in the feedstock, the catalyst could also be used for the production of fuels (gasoline, diesel, aviation fuel / jet fuel).

[0388] Catalysts prepared for CO2 hydrogenation can also be used for CO hydrogenation, and vice versa.

[0389] 3. Jet engine fuel production by CO2 hydrogenation

[0390] Jet engine fuel or aviation fuel is used in gas turbine engines to power aircraft. The main components of jet engine fuel are linear and branched alkanes and cycloalkanes, with a typical carbon chain length distribution of C8 to C 18 and preferably a carbon chain length distribution of C8 to C 16 .

[0391] Hydrocarbons in the jet engine fuel range are produced in the CO2 hydrogenation product using the catalysts disclosed herein.

[0392] Catalyst preparation

[0393] The catalyst is prepared by the organic combustion method. The Fe-Mn-K catalyst precursor is prepared by mixing citric acid monohydrate (99%, Sigma-Aldrich) with iron(III) nitrate nonahydrate (98%, Sigma-Aldrich), manganese(II) nitrate tetrahydrate (97%, Sigma-Aldrich), and potassium nitrate (99%, Sigma-Aldrich). The molar ratio of citric acid: (Fe + Mn + K) is 2, and the weight ratio of (Fe precursor and Mn precursor and K precursor + citric acid): water is 2:1. The mixture is stirred to form a homogeneous aqueous solution and heated at 50 °C for 1 to 2 hours to obtain a citric acid-based slurry. The paste is calcined in static air at 350 °C (furnace temperature) for 4 hours to produce a powder.

[0394] Catalysts with different transition metal (Mn, Cu, Zn) promoters were also prepared using the same method, and the catalysts Fe-Cu-K and Fe-Zn-K were prepared using the transition metal precursors of copper(II) nitrate trihydrate (99% to 104%, Sigma-Aldrich) and zinc(II) nitrate hexahydrate (98%, Sigma-Aldrich), respectively.

[0395] Catalysts of Fe-Mn-Li, Fe-Mn-Na, and Fe-Mn-Cs with different alkali metal promoters were prepared using the precursors of lithium carbonate (99%, Sigma-Aldrich), sodium carbonate (99.6%, Acros Organics), and cesium carbonate (99%, Sigma-Aldrich), respectively.

[0396] In each case, the molar ratio of Fe: transition metal: alkali metal is 10:1:1.

[0397] The Fe-Mn-K catalyst was also prepared using organic compounds other than citric acid. The organic compounds used were urea (Bio-Reagent, Sigma-Aldrich), tannic acid (ACS reagent, Sigma-Aldrich), ethylenediaminetetraacetic acid (EDTA, 99.5%, Fisher Scientific), oxalic acid (99.0%, Sigma-Aldrich), nitrilotriacetic acid (NTA, 99%, Sigma-Aldrich), diethylenetriaminepentaacetic acid (DTPA, 98%, Sigma-Aldrich), tartaric acid (99.5%, Sigma-Aldrich), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA, 98%, Sigma-Aldrich), salicylic acid (99.0%, Sigma-Aldrich). Unless otherwise stated, citric acid was used as the organic compound to prepare the catalyst.

[0398] Catalyst performance evaluation

[0399] As described above, the CO2 hydrogenation experiment was carried out in a fixed-bed reactor. Before the reaction, the catalyst precursor was in-situ reduced with syngas (H2:CO = 2:1) at atmospheric pressure, where the GHSV (gas hourly space velocity) was 1000 mL g -1 hour -1 , for 24 hours at 320 °C. After the reactor temperature was cooled to below 50 °C, a mixture of a gas with an H2 / CO2 ratio of 3 and N2 (as an internal standard gas) was introduced into the reactor at a gas flow rate of 40 mL min -1 (GSVH = 2400 mL g -1 hour -1 ). The reactor was heated at a heating rate of 2 °C / min until the reaction temperature (300 °C). The reaction pressure was fixed at 10 bar (1 Mpa) by a back pressure regulator.

[0400] The effluent gas products were analyzed on an on-line gas chromatograph (Perkin Elmer Clarus 580GC) equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD), and the collected liquid products were analyzed by a gas chromatograph-mass spectrometer (SHIMADZU GCMS-QP2010 SE).

[0401] The CO2 and H2 conversion rates and product selectivities were calculated as described above.

[0402] Characterization methods

[0403] The powder X-ray diffraction (XRD) analysis of the catalyst was carried out on a Bruker D8 Advance diffractometer using a Cu Kα (0.15418 nm) X-ray source (25 kV, 40 mA). The diffraction patterns were recorded in the 2θ angle range from 10° to 80° with a step size of 0.016°. The crystallite size was determined using the Scherrer equation.

[0404] X-ray photoelectron spectroscopy (XPS) of the samples was performed using a Thermo Fisher Scientific Nexsa spectrometer. The samples were analyzed using a microfocus monochromatic Al X-ray source (72 W) over an area of approximately 400 mm. The data for the full-spectrum scan were recorded at a pass energy of 150 eV, and the data for the high-resolution scan were recorded at a pass energy of 40 eV, with step sizes of 1 eV and 0.1 eV, respectively. Charge neutralization was achieved using a combination of low-energy electrons and argon ions. The resulting spectra were analyzed using Casa XPS peak-fitting software, and the sample charge was corrected using the C1s signal at 284.8 eV as a reference.

[0405] The morphology of the catalyst was characterized by scanning electron microscopy (SEM) on a scanning electron microscope (SEM, JEOL 840F).

[0406] High-resolution transmission electron microscopy (HRTEM) images were obtained in a probe-corrected JEOL ARM200F operated at 200 kV using a Gatan GIF Quantum 965ER spectrometer.

[0407] The catalytic performance of the Fe-Mn-K (10:1:1) catalyst for CO2 hydrogenation.

[0408] In the case of the Fe-Mn-K (10:1:1) catalyst prepared with citric acid as described above, the conversions of CO2 and H2 in terms of product selectivity are shown in Figure 9 . Figure 9 It is shown that the conversions of CO2 and H2 increase rapidly with reaction time within the first 5 hours, reaching about 40%; from the start of the reaction until 20 hours of reaction time, the methane selectivity decreases from 30% to 10%. In contrast, the selectivity of the liquid product (C 5+ ) remains stable at about 60% and shows a slight increase with reaction time.

[0409] The GC-MS spectra of the liquid products collected from CO2 hydrogenation are shown in Figure 10 . Figure 10 It is shown that the Fe-Mn-K catalyst has a high selectivity for hydrocarbons in the jet engine fuel range in the liquid products, and the selectivity of the total jet engine fuel range hydrocarbons reaches 47.8%.

[0410] Catalyst Characterization

[0411] The powder X-ray diffraction (XRD) spectra of the above catalyst precursor, activated catalyst, and used catalyst are shown in Figure 11 .

[0412] The surface elemental composition and oxidation state of the metal were analyzed by XPS in the range of 0 eV to 1350 eV. The measured spectra ( Figure 12 a) showed that the sample contained Fe, Mn, K, and O. Figure 12 b shows the XPS spectrum in the Fe 2p region, which can be fitted with two spin-orbit doublets of the Fe 2p 3 / 2 and Fe 2p 1 / 2 peaks and shakeup satellite peaks attributed to Fe 3+ , and these peaks are consistent with the reported Fe3O4. The molar ratio of Fe 2+ :Fe 3+ is 1:2.34, which is very close to the stoichiometry of Fe3O4.

[0413] Scanning electron microscopy (SEM) images of the catalyst and used catalyst are shown in Figure 13 . The catalyst precursor shows regular particles with clear packing ( Figure 13 (a)), and the morphology of the catalyst changes significantly after use ( Figure 13 (b)), indicating a change in the catalyst surface before and after the reaction.

[0414] High-resolution transmission electron microscopy (HRTEM) of the catalyst precursor and used catalyst are shown in Figure 14 . Figure 14 a shows the particle size of the catalyst precursor (about 15 nm), and there is no obvious change in the particle size after the reaction ( Figure 14 d). The lattice spacings of 0.25 nm and 0.3 nm correspond to the (311) and (220) planes of Fe3O4 on the catalyst precursor, respectively ( Figure 14 b and Figure 14 c). In addition to the Fe3O4 phase ( Figure 14 e), the Fe5C2 phase was also observed on the used catalyst ( Figure 14 f).

[0415] Effect of Transition Metals on the Product Curve

[0416] The catalysts Fe-Zn-K and Fe-Cu-K were prepared in the same way as the catalyst Fe-Mn-K. For different catalysts, the catalytic performance of CO2 hydrogenation is shown in Table 23. The molar ratio of K and Mn (Zn or Cu) to Fe is 1:10, and the data were obtained at a reaction time of 20 h.

[0417] Table 23

[0418]

[0419] C 2-4 =: C2 - C4 olefins, C 2-4 0: C2 - C4 alkanes; C 5+ : Liquid products; C 8-16 : Hydrocarbons in the jet engine fuel range.

[0420] Effect of alkali metals on the product curve

[0421] Different alkali metals were also used as promoters for the CO2 hydrogenation catalyst, and the catalytic performance is listed in Table 24. The molar ratio of alkali metal and Mn to Fe is 1:10, and the data were obtained at a reaction time of 20 h.

[0422] Table 24

[0423]

[0424] It can be seen from Table 24 that Na, K, and Cs exhibit both high activity for CO2 hydrogenation and high selectivity for the jet engine fuel range. Compared with the catalysts Fe-Mn-Na and Fe-Mn-Cs, the Fe-Mn-K catalyst shows slightly better performance in terms of CO2 conversion and target product selectivity.

[0425] Effect of organic compounds on the product curve

[0426] A series of Fe-Mn-K (molar ratio 10:1:1) catalysts were prepared with different organic compounds in the catalyst preparation, and their catalytic performance in CO2 hydrogenation is shown in Table 25.

[0427] Table 25

[0428]

[0429] Obviously, compared with the catalysts prepared without organic compounds, all Fe-Mn-K catalysts prepared with organic compounds exhibit both higher CO2 conversion and higher selectivity for hydrocarbons in the jet engine fuel range. The catalysts prepared with EDTA, citric acid, oxalic acid, NTA, DTPA, tartaric acid, HEDTA, and salicylic acid show better catalytic performance.

[0430] All references cited herein (including publications, patent applications, and patents) are hereby incorporated by reference in their entirety, to the same extent as if each reference had been individually and specifically indicated to be incorporated by reference and were set forth in full herein (to the maximum extent permitted by law).

[0431] All headings and subheadings used herein are for convenience only and shall not be construed as limiting the invention in any way.

[0432] The use of any and all examples or exemplary language (e.g., "such as") provided herein is for illustrative purposes only and is not intended to limit the scope of the invention, unless otherwise specified. No language in this specification should be construed as indicating that any non-illustrative element is essential to the practice of the invention.

[0433] The citation and incorporation of patent documents herein are for convenience only and do not reflect any opinion as to the validity, patentability, and / or enforceability of such patent documents.

[0434] The invention includes all modifications and equivalents of the subject matter recited in the appended paragraphs as permitted by applicable law.

Claims

1. A catalyst for the hydrogenation of carbon dioxide and / or carbon monoxide, characterized in that, the catalyst comprises an iron substance, manganese or its oxide, cobalt or its oxide, an alkali metal, and optionally at least one selected from zinc and copper.

2. The catalyst according to claim 1, characterized in that, The catalyst comprises iron carbide, manganese or its oxide, cobalt or its oxide, and an alkali metal.

3. The catalyst according to claim 1 or 2, characterized in that, The alkali metal is potassium.

4. The catalyst according to any one of claims 1 to 3, characterized in that, Fe: The molar ratio of Mn is from 100:1 to 4:

1.

5. The catalyst according to claim 4, characterized in that, The molar ratio of Fe:Mn is from 15:1 to 5:

1.

6. The catalyst according to any one of claims 3 to 5, characterized in that, The molar ratio of Fe:alkali metal is from 100:1 to 2:

1.

7. The catalyst according to claim 6, wherein The molar ratio of Fe:alkali metal is from 20:1 to 4:

1.

8. The catalyst according to any one of claims 1 to 7, characterized in that, The iron carbide is Fe5C2.

9. A method for preparing the catalyst according to any one of claims 1 to 8, characterized in that, Comprising the following steps: (a) Combining the iron substance, manganese or its salt, its oxide or its hydroxide, cobalt or its salt, its oxide or its hydroxide, the alkali metal or its salt, optionally at least one selected from zinc and copper, and a complexing agent to obtain a catalyst precursor; (b) Calcining the catalyst precursor; (c) Activating the catalyst precursor.

10. The method according to claim 9, wherein The activation in step (c) includes: exposing the calcined catalyst precursor to a mixture of carbon monoxide and hydrogen at a temperature of 250°C to 500°C.

11. The method according to claim 9 or 10, characterized in that, The complexing agent is selected from citric acid, tartaric acid, oxalic acid, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), and HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid), or its salts.

12. The method according to claim 11, wherein The complexing agent is citric acid.

13. A method for carbon dioxide hydrogenation, characterized in that, Comprising: Contacting a raw material containing hydrogen and carbon dioxide with the catalyst according to any one of claims 1 to 8 at a temperature of 180°C to 500°C and / or at a pressure of 0.5 MPa to 20 MPa.

14. A method for carbon monoxide hydrogenation, characterized in that, Comprising: Contacting a raw material containing hydrogen and carbon monoxide with the catalyst according to any one of claims 1 to 8 at a temperature of 180°C to 500°C and / or at a pressure of 0.5 MPa to 20 MPa.

15. A method for producing hydrocarbons, characterized in that, Comprising: Contacting a raw material containing (i) hydrogen and (ii) carbon monoxide and / or carbon dioxide with the catalyst according to any one of claims 1 to 8 at a temperature of 180°C to 500°C and / or at a pressure of 0.5 MPa to 20 MPa.

16. The method according to claim 15, wherein The hydrocarbon is C 5+ hydrocarbon.

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