Iron / silicon / potassium-based fischer-tropsch catalyst materials and processes for making and using same

Abstract

The present disclosure relates generally to a Fischer-Tropsch catalyst material comprising at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10. In various embodiments, the Fischer-Tropsch catalyst material also includes copper, in a molar ratio of copper to iron in the range up to 0.12. Also provided are carbided versions of such catalyst materials, and methods for making and using the same,

Description

IRON / SILICON / POTASSIUM-BASED FISCHER-TROPSCH CATALYST MATERIALS AND PROCESSES FOR MAKING AND USING SAMECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority U.S. provisional application number 63 / 616,370, filed December 29, 2023 and European Patent application number 24166548.8, filed March 26, 2024, each of which is incorporated by reference herein in its entirety.BACKGROUND OF THE DISCLOSURE1 _ Field

[0002] The present disclosure relates generally to Fischer-Tropsch catalyst materials, processes of making the same, and Fischer-Tropsch processes using the Fischer-Tropsch catalyst materials described herein.2. _ Technical Background

[0003] The conversion of synthesis gas (i.e. , a mixture of carbon monoxide and hydrogen, also known as syngas) into hydrocarbons by the Fischer-Tropsch process has been known for decades, but has historically lagged in performance compared to other hydrocarbon synthesis techniques. The growing importance of alternative energy sources has resulted in renewed interest in the Fischer-Tropsch (FT) process as it allows a direct and environmentally-acceptable route to high-quality fuels and feedstock chemicals.

[0004] Fischer-Tropsch processes are known for producing linear hydrocarbons, as well as oxygenates, that can be useful in fuels and can also serve as valuable feedstock chemicals. The hydrocarbon fuel derived from Fischer-Tropsch processes is typically better able to meet increasingly stringent environmental regulations compared to conventional refinery-produced fuels, as FT-derived fuels typically have lower contents of sulfur, nitrogen, and aromatic compounds, which contribute to the emission of potent pollutants such as SO2, NOx, and particulates. Alcohols, olefins and other oxygenates obtained may also be used as reagents in other processes, such as in the synthesis of lubricants.

[0005] Currently, cobalt-based catalysts are the primary type of catalysts used in Fischer-Tropsch processes; they generally yield linear paraffins as primary hydrocarbon products. Iron-based catalyst materials are also known, and can be lower in cost compared to cobalt-based catalyst materials. Iron-catalysed FT typically produces as part of the hydrocarbon product a significant amount of long-chain oxygenates and long-chain a-olefins, which in many cases are desirable products. Moreover, in contrast to cobalt, iron-based catalysts generally exhibit high water-gas shift (WGS) activity. The water-gas shift reactioncompetes with the Fischer-Tropsch process by converting CO and H2O to CO2and hydrogen, as shown below:Accordingly, higher WGS activity leads to high CO2yields and lower selectivity of the conversion of feedstock carbon monoxide to C5+ hydrocarbons, which are the generally- desired Fischer-Tropsch products. While the WGS activity of iron-based Fischer-Tropsch catalysts can be useful in some cases for syngas feeds having low H2 / CO ratios (e.g., from coal or biomass), the WGS activity undesirably decreases the conversion CO into desired products.

[0006] As such, there is a need to provide improved iron-based Fischer-Tropsch catalysts and iron-based Fischer-Tropsch processes.SUMMARY

[0007] In one aspect, the present disclosure provides a Fischer-Tropsch catalyst material comprising at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10.In various embodiments, the Fischer-Tropsch catalyst material also includes copper, in a molar ratio of copper to iron in the range up to 0.12.

[0008] Another aspect of the present disclosure provides a process of making a Fischer- Tropsch catalyst material, the process comprising: providing a first liquid comprising one or more iron-containing compounds dissolved in a solvent; contacting the one or more first liquids with precipitating ions in the presence of potassium ions to provide an potassium-containing precipitate and a supernatant; isolating the potassium-containing precipitate from the supernatant; optionally, washing the isolated precipitate with a washing liquid to reduce concentration of alkali metal thereof; and calcining the isolated precipitate to provide the Fischer-Tropsch catalyst material.

[0009] Another aspect of the present disclosure provides a process of making a Fischer- Tropsch catalyst material, the process comprising: providing one or more first liquids each comprising one or more iron-containing compounds dissolved in one or more first solvents;contacting the one or more first liquids with precipitating ions in the substantial absence of alkali metal ions to provide a substantially alkali-free precipitate and a supernatant; isolating the substantially alkali-free precipitate from the supernatant; adding potassium metal ions to the substantially alkali-free precipitate in order to provide a potassium-containing precipitate; and calcining the isolated precipitate to provide the Fischer-Tropsch catalyst material.

[0010] Another aspect of the present disclosure provides a Fischer-Tropsch catalyst material made by a process as described herein.

[0011] Another aspect of the present disclosure provides a carbided Fischer-Tropsch catalyst material, e.g., a Fischer-Tropsch catalyst material as described herein in a carbided form.

[0012] Another aspect of the present disclosure provides a carbided Fischer-Tropsch catalyst material comprising at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10, wherein at least 50 atom% of the iron of the carbided Fischer-Tropsch catalyst material is in the form of iron carbide. Such materials can be made, e.g., by the carbiding of the oxidic catalyst materials described herein. The carbided Fischer-Tropsch catalyst material can in some embodiments include copper, in a molar ratio of copper to iron in the range up to 0.12.

[0013] Another aspect of the present disclosure provides a process for providing a carbided Fischer-Tropsch catalyst material as described herein, the process comprising: providing a Fischer-Tropsch catalyst material as described herein (e.g., made by the process as described herein); optionally, treating the Fischer-Tropsch catalyst material with a reducing gas stream comprising hydrogen for a time and at a temperature sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in metallic form; and then treating the Fischer-Tropsch catalyst material with a carbiding gas stream comprising carbon monoxide and / or carbon dioxide (e.g., carbon monoxide), at a temperature of at least 180 °C for a time sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in a carbided form (e.g., for at least 5 hours).

[0014] Another aspect of the present disclosure provides a process for performing a Fischer-Tropsch process, the process comprising providing a carbided Fischer-Tropsch catalyst material as described herein (e.g., or made by a process described herein); contacting at a reaction temperature and at a pressure the carbided Fischer-Tropsch catalyst material with a feed stream comprising H2and CO to provide a product stream comprising C5+ hydrocarbons.BRIEF DESCRIPTION OF FIGURES

[0015] The accompanying drawings are included to provide a further understanding of the processes of the disclosure, and are incorporated in and constitute a part of this specification. The drawings are not necessarily to scale, and sizes of various elements may be distorted for clarity. The drawings illustrate one or more embodiment(s) of the disclosure and together with the description serve to explain the principles and operation of the disclosure.

[0016] FIG. 1 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0017] FIG. 2 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0018] FIG. 3 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0019] FIG. 4 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0020] FIG. 5 is a graph depicting the effects of various reaction parameters when performing a Fischer-Tropsch process as described herein.

[0021] FIG. 6 is an X-ray diffraction pattern of a calcined Fischer-Tropsch catalyst material as described herein.

[0022] FIG. 7 is a set of Mdssbauer spectra of Fischer-Tropsch catalyst materials activated by carbiding processes as described herein.

[0023] FIG. 8 is a set of Mdssbauer spectra of Fischer-Tropsch catalyst materials activated by carbiding processes as described herein.DETAILED DESCRIPTION

[0024] The present inventors have determined that there is a need to reduce the WGS activity of iron-based catalysts in order to provide better CO-to-Cs+ conversion in Fischer-Tropsch processes. The present inventors note that cobalt is expensive and relatively scarce, and that iron is abundant and cheap, and thus that iron-based Fischer-Tropsch catalysts can advantageously be more economical and sustainable then cobalt-based Fischer-Tropsch catalysts. However, iron-based Fischer-Tropsch catalysts suffer from high WGS activity, leading to substantial carbon loss during the Fischer-Tropsch process. The present disclosure relates, inter alia, to improved iron-based Fischer-Tropsch catalysts and iron catalyzed Fischer-Tropsch processes having relatively low WGS activity.

[0025] The present inventors have found that limiting the amount of alkali metal and copper in the catalyst can decrease both WGS activity (i.e. , CO2 selectivity) and C1-C4 selectivity while increasing C5+ selectivity to provide catalysts that can generally mimic cobalt-based Fischer-Tropsch catalyzed processes. Additionally, the present inventors have found that this selectivity for C5+ hydrocarbons with iron-based catalysts can be accomplished at relatively low Fischer-Tropsch reaction temperatures. Further, by increasing the H2 / CO ratio to approaching and even greater than 2:1 , the WGS activity of the iron-based catalyst can be further suppressed. Accordingly, the present disclosure provides iron-based Fischer-Tropsch catalysts with low WGS activity, processes of making the same, and Fischer-Tropsch processes using the same with better carbon recovery in desirable C5+ products.

[0026] Fischer-Tropsch Catalyst Materials

[0027] As described above, the present inventors have developed iron-based Fischer- Tropsch catalyst materials that can advantageously provide relatively low WGS activity when used in Fischer-Tropsch syntheses. Thus, in one aspect, the present disclosure provides a Fischer-Tropsch catalyst material comprising at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; copper , in a molar ratio of copper to iron in the range up to 0.12; and potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10. These catalyst materials can be synthesized, stored and transported, e.g., as oxidic materials, as is common for catalyst materials. As the person of ordinary skill in the art will appreciate, during Fischer-Tropsch synthesis the active catalytic species is actually iron carbide - but regardless of form the Fischer-Tropsch catalyst materials described here can provide relatively low water-gas shift activity together with a suite of other desirable properties when carbided (e.g., in situ in a Fischer Tropsch reactor, especially when carbided at high temperature) and used in Fischer- Tropsch synthesis.

[0028] Amounts of various atomic species as described herein are determined using inductively coupled plasma mass spectrometry (“ICP”). As the person of ordinary skill in theart will appreciate, ICP can detect most elements, but is blind to hydrogen, nitrogen and oxygen. Accordingly, amounts determined by ICP that are quantified “on an elemental basis” are determined with respect to amounts of ICP-measurable elements, i.e., excluding hydrogen, oxygen and nitrogen. Carbon is detectable by ICP. But in order to maintain consonance between various amounts of materials in various catalyst states, amounts of various atomic species in catalyst materials can also quantified “on an elemental basis exclusive of carbon,” i.e., determined with respect to amounts of ICP-measurable elements, excluding hydrogen, oxygen, nitrogen and carbon. Quantifications are made without reference to the form in which the atomic species are present (e.g., oxide, metal, carbide, etc.).

[0029] The Fischer-Tropsch catalyst materials described herein (e.g., whether in oxide or carbided form) comprise iron. The iron may be present in the catalyst in a variety of forms; most commonly, iron is principally present as metal, metal carbide, metal oxide; a metal halide, or a combination thereof. For example, in various embodiments as described herein, the Fischer-Tropsch catalyst material comprises at least 80 wt% iron, e.g., at least 85 wt% iron, on an elemental basis exclusive of carbon. In various embodiments as described herein, the Fischer-Tropsch catalyst material comprises at least 90 wt% iron, e.g., at least 92 wt% iron, on an elemental basis exclusive of carbon.

[0030] The Fischer-Tropsch catalyst materials described herein (e.g., whether in oxide or carbided form) also include silicon, in a molar ratio of silicon to iron in the range of 0.01- 0.12. Silicon will typically be principally present in the form of silicon oxide, iron silicate, silicon hydride, silicon metal, or a combination thereof. In various embodiments, the molar ratio of silicon to iron is in the range of 0.01-0.10, e.g., 0.01-0.08, or 0.01-0.06. In various embodiments, the molar ratio of silicon to iron is in the range of 0.02-0.12, e.g., 0.02-0.10, or 0.02-0.08, or 0.02-0.06. In various embodiments, the molar ratio of silicon to iron is in the range of 0.03-0.12, e.g., 0.03-0.10, or 0.03-0.08, or 0.03-0.06.

[0031] The Fischer-Tropsch catalyst materials described herein (e.g., whether in oxide or carbided form) also include potassium, in a molar ratio of potassium to iron in the range of 0.003-0.10. Potassium will typically be principally present in the form of potassium oxide, potassium silicate, potassium metal, potassium halide, or a combination thereof. In various embodiments, the molar ratio of potassium to iron is in the range of 0.003-0.08, e.g., 0.003- 0.06, or 0.003-0.04. In various embodiments, the molar ratio of potassium to iron is in the range of 0.006-0.10, e.g., 0.006-0.08, or 0.006-0.06, or 0.006-0.04. In various embodiments, the molar ratio of potassium to iron is in the range of 0.009-0.10, e.g., 0.009-0.08, or 0.009- 0.06, or 0.009-0.04. The present inventors have found that, despite the tendency of alkali metals to increase water-gas shift activity, the catalysts of the disclosure can have relativelylow water-gas shift activity, especially when carbided as described herein. But the person of ordinary skill in the art can select amounts of potassium toward the lower end of the described range to help further minimize water-gas shift activity.

[0032] The Fischer-Tropsch catalyst materials described herein (e.g., whether in oxide or carbided form) can, in some embodiments, also include copper, in a molar ratio of copper to iron in the range up to 0.12. Copper will typically be principally present in the form of copper oxide, copper silicate, copper metal, copper halide, or a combination thereof. In various embodiments, the molar ratio of copper to iron is up to 0.10, e.g. up to 0.08, or up to 0.06. In various embodiments, the molar ratio of copper to iron is in the range of 0.005-0.12, e.g., in the range of 0.005-0.10, or 0.005-0.08, or 0.005-0.06. In various embodiments, the molar ratio of copper to iron is in the range of 0.01-0.12, e.g., in the range of 0.01-0.10, or 0.01-0.08, or 0.01-0.06. In various embodiments, the molar ratio of copper to iron is in the range of 0.02 0.12, e.g., in the range of 0.02-0.10, or 0.02-0.08, or 0.02-0.06. In various embodiments, the molar ratio of copper to iron is in the range of 0.02-0.12, e.g., in the range of 0.02-0.10, or 0.02-0.08, or 0.02-0.06. The present inventors note that copper can be helpful in the conversion of iron to carbide form. The present inventors also note that copper can be helpful in increasing CO conversion, especially when the carbided Fischer-Tropsch catalyst material has a significant amount of x-Fe5C2, for example, via activation with high temperature carbiding, as described below. However, when high amounts of copper are present in a Fischer-Tropsch material, the selectivity of the ultimately carbided material for water-gas shift processes can undesirably increase. But the present inventors note that low water-gas shift activity can be provided by the materials of the disclosure, even when they do contain copper. Nonetheless, the person of ordinary skill in the art can, based on the present disclosure, use relatively lower amounts of copper to provide reduced water-gas shift activity of the carbided Fischer-Tropsch catalyst material.

[0033] The present inventors note, however, that the inclusion of copper in the Fischer- Tropsch catalyst material can in many cases be undesirable. While copper has the benefit of increasing Fischer-Tropsch activity, it can also increase water-gas shift activity, which may be undesirable from the standpoint of overall CO conversion, i.e. , due to conversion of CO to CO2. This can be especially true when the catalyst comprises significant amounts of the q- Fe2C and e-FesC carbide forms as described below, e.g., when the Fischer-Tropsch catalyst material is activated using a low temperature carbiding method. Thus, in certain embodiments as otherwise described herein, the Fischer-Tropsch catalyst material is essentially free of copper (e.g., the molar ratio of copper to iron is no more than 0.01 , or no more than 0.005, or nor more than 0.001).

[0034] The present inventors have determined that only relatively small total amounts of silicon, copper (if present), and potassium need be present to provide an advantageous Fischer-Tropsch catalyst material. For example, in various embodiments as otherwise described herein, a molar ratio of the sum of silicon, copper (if present), and potassium to iron is in the range of 0.04-0.18, e.g., 0.4-0.14, or 0.4-0.10, or 0.05-0.18, or 0.5-0.14, or 0.5- 0.10, or 0.06-0.18, or 0.06-0.14, or 0.06-0.10.

[0035] While the materials of the disclosure need not contain any other metallic elements than iron, silicon, copper (if desired), and potassium, the present inventors note that in various embodiments other metallic elements can be present. For example, in various embodiments, the Fischer-Tropsch catalyst materials of the disclosure further include manganese, in a molar ratio of manganese to iron in the range up to 0.05, e.g., up to 0.04, or up to 0.03. For example, in various embodiments, manganese is present in a molar ratio of manganese to iron in the range of 0.005-0.05, e.g., 0.005-0.04, or 0.005-0.03, or 0.01-0.05, or 0.01-0.04, or 0.01-0.03.

[0036] In various embodiments of the Fischer-Tropsch catalyst materials of the disclosure, a molar ratio of lithium to iron is no more than 0.003, e.g., no more than 0.002, or no more than 0.001. The present inventors have determined that advantageous Fischer- Tropsch catalyst materials can be provided even in the absence of substantial amounts of lithium.

[0037] In various embodiments of the Fischer-Tropsch catalyst materials of the disclosure, a molar ratio of silver to iron is no more than 100 ppm, e.g., no more than 25 ppm, or no more than 10 ppm, or no more than 5 ppm, or no more than 3 ppm. The present inventors have determined that advantageous Fischer-Tropsch catalyst materials can be provided even in the absence of substantial amounts of silver.

[0038] In some embodiments as described herein, the Fischer-Tropsch catalyst material is in substantially oxidic form (i.e. , a substantially non-metallic, non-carbided form). As described above, the oxidic form is the result of calcining, and can be especially convenient for storage and transport. As such, in various embodiments as described herein, the Fischer-Tropsch catalyst material is in a substantially non-metallic, non-carbide form. For example, in various embodiments as described herein, the iron, silicon, copper (if present) and potassium are substantially present as metal oxides (e.g., with a small amount of metal halide). Such materials can be the result of the precipitation, drying and calcining processes as described herein. The person of ordinary skill in the art will appreciate that oxidic catalyst materials such as these can be activated by carbiding to provide active catalyst materials for use in Fischer-Tropsch processes.

[0039] In various embodiments as described herein, the Fischer-Tropsch catalyst material (whether in oxidic, reduced or metallic form) is an unsupported catalyst material. The present inventors note that the silicon can provide sufficient structural integrity to the materials that they can be used as bulk catalysts. As such, in some embodiments as described herein, at least 90 wt% of the Fischer-Tropsch catalyst material is made up of iron, silicon, copper (if present), and potassium, and, if present, manganese, quantified on an elemental basis exclusive of carbon, as determined by ICP. For example, in various embodiments as described herein, at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.5 wt%, or at least 99.8 wt% of the Fischer-Tropsch catalyst material is made up of silicon, copper (if present), and potassium, and, if present, manganese, on an elemental basis exclusive of carbon.

[0040] The person of ordinary skill in the art will appreciate that the Fischer-Tropsch catalyst materials of the disclosure can be provided in many forms, depending especially on the particular form of the reactor system in which they are to be used, e.g., in a fixed bed reactor, a fluid bed reactor, a bubble column reactor, a so-called CANS reactor.

[0041] Processes for Making Fischer-Tropsch Catalyst Materials

[0042] As described above, the present disclosure also provides processes for making a Fischer-Tropsch catalyst material (e.g., as described herein). Two particular precipitationbased processes for making catalyst materials are provided in detail in this disclosure: one that has potassium present during the precipitation, and one that uses post-precipitation impregnation of potassium. In cases where potassium is present during the precipitation, concentration of potassium can be lowered by using additional washing to further reduce the amount of alkali. Copper and manganese can be included via coprecipitation, via precipitation in the presence of copper, or via impregnation in a later step. Silicon can be added by treatment of the precipitate with a silicon source such as tetraethylorthosilicate during or after precipitation.

[0043] One process includes providing a first liquid comprising one or more iron- containing compounds dissolved in a first solvent; contacting the first liquid with precipitating ions in the presence of potassium ions to provide a potassium-containing precipitate and a supernatant; isolating the potassium-containing precipitate from the supernatant; optionally, washing the isolated precipitate with a washing liquid to reduce concentration of potassium thereof; and calcining the isolated precipitate to provide the Fischer-Tropsch catalyst material. Here, the precipitation is performed in the presence of potassium ions. Without intending to be bound by theory, the present inventors surmise that while the potassium ions may not themselves substantially precipitate, the potassium-containing supernatant wets theprecipitate sufficiently to provide significant alkali content to the precipitate once isolated. If necessary, this can be reduced to a desired low level by the washing with the washing liquid.

[0044] The iron-containing compounds are not particularly limited and the person of ordinary skill in the art would be able to choose appropriate compounds that are soluble in the first solvent. For example, in some embodiments of the disclosure as described herein, the iron-containing compound(s) may be selected from metal salts (e.g., nitrates and acetates). The first solvent is also not particularly limited and the person of ordinary skill in the art would be able to choose an appropriate solvent in which the iron-containing compounds are soluble. As the person of ordinary skill in the art will appreciate, a convenient choice for the first solvent is water. Other aqueous systems can also be used; an aqueous solvent including a co-solvent such as ethanol may be desirable in some cases. And in some cases, substantially non-aqueous solvents can be used, e.g., one or more of ethanol, isopropanol and acetone, optionally together with ethylene glycol to improve dispersion. As would be understood by the person of skill in the art, the iron-containing compound(s) may be provided in the first liquid in amounts relative to other species used in the overall process to provide the Fischer-Tropsch catalyst material with a desired amount of iron as described herein.

[0045] The person of ordinary skill in the art will provide the first liquid at a desirable pH at which the iron compound(s) remain soluble. For example, in various embodiments, each of the one or more first liquids has a pH of no greater than 7.

[0046] The first liquid is contacted with precipitating ions in the presence of potassium ions to provide a potassium-containing precipitate. As the person of ordinary skill in the art will appreciate, this can be conveniently performed by addition of a solution of precipitating ions into a first liquid that includes the iron-containing compounds; addition of the first liquid into a solution of precipitating ions; or combination of the first liquid with a solution of precipitating ions in a separate vessel. The potassium ions can provided, e.g., as a salt of a non-precipitating ion; in the solution of precipitating ions, e.g., as a counterion to precipitation ions; or dissolved in a separate liquid.

[0047] The person of ordinary skill in the art can select desirable precipitating ions. In various embodiments, the precipitating ions are carbonate ions and / or hydroxide ions. The precipitating ions can be provided by use of a potassium-containing base to provide both precipitating ions and potassium ions, e.g., a potassium carbonate or a potassium hydroxide. In some embodiments, a combination with a non-metal containing base, e.g., ammonium carbonate or ammonium hydroxide, can be used to provide the potassium-containing precipitate with a desired level of potassium without the need for washing. As an alternative,a non-metal containing base can be used to provide substantially all the precipitating ions, with a separate potassium salt (e.g., as a nitrate or an acetate) providing the potassium.

[0048] As the person of ordinary skill in the art will appreciate, it can be desirable to perform the precipitation at a desirable alkaline pH. For example, in various embodiments, the contacting of the one or more first liquids with the precipitating ions is performed at precipitation pH in the range of 8-12, e.g., in the range of 8-11, or 8-10, or 8.5-12, or 8.5-11 , or 8.5-10, or 9-12, or 9-11, or 9-10.. It can be desirable to maintain the pH of the precipitation within certain alkaline pH values. For example, in various embodiments, the process further comprises maintaining the pH of the contacting step at an alkaline pH, for example, in the range of 8-12, e.g., in the range of 8-11 , or 8-10, or 8.5-12, or 8.5-11 , or 8.5- 10, or 9-12, or 9-11 , or 9-10. The pH of the contacting can be maintained, for example, by controlling a rate of addition of precipitating ions. The person of ordinary skill in the art can otherwise maintain desirable precipitation pH values by maintaining flow rates in the combination of liquids, and, if necessary, addition of additional acid or base components.

[0049] In various embodiments as described herein, the contacting of the one or more first liquids with the precipitating ions is conducted at an elevated temperature. For example, in some embodiments as described herein, the contacting step is conducted at a temperature in the range of 60-100 °C, or 60-90 °C, or 60-80 °C, or 70-100 °C, or 70-90 °C, or 70-80 °C.

[0050] In some embodiments as described herein, the process further comprises aging the precipitate in contact with the supernatant. The aging process is not particularly limited. For example, in some embodiments as described herein, the aging is conducted at a temperature in the range of 60-100 °C, or 60-90 °C, or 60-80 °C, or 70-100 °C, or 70-90 °C, or 70-80 °C. In some embodiments as described herein, the aging is conducted for a time in the range of 1-5 hours, or 1-4 hours or 1-2 hours.

[0051] To provide silicon, the precipitate can be treated with a silicon source such as tetraethylorthosilicate. The timing of the treatment can be varied; it can be conveniently added to the precipitate during precipitation and / or aging, so that the alkaline conditions of the precipitation can cause the silicon source to react to form solid. Of course, the precipitate can be treated with a silicon source at a later time to provide silicon to the final as-calcined material.

[0052] The potassium-containing precipitate is then isolated from the supernatant. A variety of methods can be used in the isolation, including filtration, centrifugation, and settling and decanting.

[0053] In some embodiments, the amount of potassium present in the contacting step is sufficient to provide the isolated precipitate with a desired level of potassium. However, in other cases, washing the isolated precipitate with a washing liquid can be performed to reduce the potassium content thereof. The washing process is not particularly limited. In some embodiments as described herein, washing the isolated precipitate is repeated until a desired level of potassium is provided to the Fischer-Tropsch catalyst material. In some embodiments as described herein, the process includes repeating the washing step at least twice (e.g., at least three times or at least four times). The washing liquid is also not particularly limited and the person of ordinary skill in the art would be able to choose an appropriate liquid. For example, in some embodiments of the disclosure as described herein, the washing liquid is water. However, the present inventors note that the high surface tension of the residual water from the washing step can lead to pores collapsing during the subsequent drying step. As such, it can sometimes be advantageous to use a non-aqueous liquid, particularly in the final washing steps, to obtain catalyst materials with larger surface area and pore volume. For example, in some embodiments as described herein, the washing liquid is a non-aqueous liquid (e.g., ethanol). In some embodiments, the washing liquid across all washing steps is one or more of water or a non-aqueous liquid, or a combination thereof.

[0054] The isolated precipitate, whether washed or not, can then be dried, for example, at an elevated temperature for a drying time. The person of ordinary skill in the art would be able to select appropriate drying apparatuses and conditions. For example, in some embodiments, the elevated temperature is in the range of 50-150 °C, e.g., in the range of 50-120 °C, or 50-100 °C, or 100-150 °C, or 100-120 °C. In some embodiments, the drying time is in the range of 1 to 48 hours, e.g., in the range of 10 to 36 hours, or 12 to 24 hours. For example, in particular embodiments, the drying time is about 24 hours. However, a separate drying operation is not necessary in all cases; in some embodiments, volatiles of the supernatant and / or washing liquid evaporate at a beginning stage of the calcining.

[0055] As noted above, process further includes calcining the precipitate to provide the Fischer-Tropsch catalyst material. The calcining step will generally convert various metallic species to oxide forms. In some embodiments of the present disclosure as described herein, calcining the precipitate is conducted for a calcining time and at a calcining temperature. For example, in some embodiments, the calcining time is in the range of 0.5 to 24 hours, or 0.5 to 15 hours, or 0.5 to 10 hours, or 0.5 to 5 hours. In some embodiments, the calcining temperature is in the range of 100-600 °C, e.g., in the range of 200-600 °C, or 300-600 °C, or 100-500 °C, or 200-500 °C, or 300-500 °C. The person of ordinary skill in the art can select calcining conditions to provide a desired high degree conversion to oxide.

[0056] In alternative process for providing the Fischer-Tropsch catalyst materials of the disclosure, the precipitation is performed in the substantial absence of potassium. To provide an potassium-containing catalyst material, a small amount of potassium can be added to the Fischer-Tropsch catalyst material at a later stage. Accordingly, in another aspect of the disclosure, a process includes providing a first liquid comprising one or more iron-containing compounds dissolved in a first solvent; contacting the first liquid with precipitating ions in the substantial absence of alkali metal ions to provide a substantially alkali-free precipitate and a supernatant; isolating the substantially alkali-free precipitate from the supernatant; adding potassium ions to the substantially alkali-free precipitate in order to provide a potassium-containing precipitate; and calcining the isolated precipitate to provide the Fischer-Tropsch catalyst material. Here, the precipitation is performed in the substantial absence of alkali metal ions, and a desired level of potassium ions can be added to the precipitated material in a separate step. This second process can otherwise be performed in a manner similar to that described above for the first process.

[0057] The iron-containing compound(s) are not particularly limited and the person of ordinary skill in the art would be able to choose appropriate compound(s)_ that are soluble in the first solvent. For example, in some embodiments of the disclosure as described herein, the iron-containing compound(s) may be selected from metal salts (e.g., nitrates and acetates). The first solvent is also not particularly limited and the person of ordinary skill in the art would be able to choose an appropriate solvent in which the iron-containing compounds are soluble. As the person of ordinary skill in the art will appreciate, a convenient choice for the first solvent is water. Other aqueous systems can also be used; a co-solvent such as ethanol may be desirable in some cases. And in some cases, substantially non-aqueous solvents can be used, e.g., one or more of ethanol, isopropanol and acetone, optionally together with ethylene glycol to improve dispersion. As would be understood by the person of skill in the art, the iron-containing compounds may be provided in amounts in the first liquid in amounts relative to other species used in the overall process to provide the Fischer-Tropsch catalyst material with a desired amount of iron as described herein.

[0058] The person of ordinary skill in the art will provide the first liquid at a desirable pH at which the iron-containing compound(s) remain soluble. For example, in various embodiments, each of the one or more first liquids has a pH of no greater than 7.

[0059] The person of ordinary skill in the art can select desirable precipitating ions. In various embodiments, the precipitating ions are carbonate ions and / or hydroxide ions. Theprecipitating ions can be provided by use of non-metal containing base, e.g., ammonium carbonate or ammonium hydroxide.

[0060] As the person of ordinary skill in the art will appreciate, it can be desirable to perform the precipitation at a desirable alkaline pH. For example, in various embodiments, the contacting of the one or more first liquids with the precipitating ions is performed at precipitation pH in the range of 8-12, e.g., in the range of 8-11, or 8-10, or 8.5-12, or 8.5-11 , or 8.5-10, or 9-12, or 9-11, or 9-10.. It can be desirable to maintain the pH of the precipitation within certain alkaline pH values. For example, in various embodiments, the process further comprises maintaining the pH of the contacting step at an alkaline pH, for example, in the range of 8-12, e.g., in the range of 8-11, or 8-10, or 8.5-12, or 8.5-11 , or 8.5- 10, or 9-12, or 9-11 , or 9-10. The pH of the contacting can be maintained, for example, by controlling a rate of addition of precipitating ions. The person of ordinary skill in the art can otherwise maintain desirable precipitation pH values by maintaining flow rates in the combination of liquids, and, if necessary, addition of additional acid or base components.

[0061] In various embodiments as described herein, the contacting of the one or more first liquids with the precipitating ions is conducted at an elevated temperature. For example, in some embodiments as described herein, the contacting step is conducted at a temperature in the range of 60-100 °C, or 60-90 °C, or 60-80 °C, or 70-100 °C, or 70-90 °C, or 70-80 °C.

[0062] In some embodiments as described herein, the process further comprises aging the precipitate in contact with the supernatant. The aging process is not particularly limited. For example, in some embodiments as described herein, the aging is conducted at a temperature in the range of 60-100 °C, or 60-90 °C, or 60-80 °C, or 70-100 °C, or 70-90 °C, or 70-80 °C. In some embodiments as described herein, the aging is conducted for a time in the range of 1-5 hours, or 1-4 hours or 1-2 hours.

[0063] To provide silicon, the precipitate can be treated with a silicon source such as tetraethylorthosilicate. The timing of the treatment can be varied; it can be conveniently added to the precipitate during precipitation and / or aging, so that the alkaline conditions of the precipitation can cause the silicon source to react to form solid. Of course, the precipitate can be treated with a silicon source at a later time to provide silicon to the final as-calcined material.

[0064] The substantially alkali-free precipitate is then separated from the supernatant. A variety of methods can be used in the isolation, including filtration, centrifugation, and settling and decanting.

[0065] In various embodiments, the process further comprises washing the isolated precipitate with a washing liquid. Here, too, the washing liquid is also not particularly limited and the person of ordinary skill in the art would be able to choose an appropriate liquid. For example, in some embodiments of the disclosure as described herein, the washing liquid is water. However, the present inventors note that the high surface tension of the residual water from the washing step can lead to pores collapsing during the subsequent drying step. As such, it can sometimes be advantageous to use a non-aqueous liquid, particularly in the final washing steps, to obtain catalyst materials with larger surface area and pore volume. For example, in some embodiments as described herein, the washing liquid is a nonaqueous liquid (e.g., ethanol). In some embodiments, the washing liquid across all washing steps is one or more of water or a non-aqueous liquid, or a combination thereof.

[0066] The isolated precipitate, whether washed or not, can then be dried, for example, at an elevated temperature for a drying time. The person of ordinary skill in the art would be able to select appropriate drying apparatuses and conditions. For example, in some embodiments, the elevated temperature is in the range of 50-150 °C, e.g., in the range of 50-120 °C, or 50-100 °C, or 100-150 °C, or 100-120 °C. In some embodiments, the drying time is in the range of 1 to 48 hours, e.g., in the range of 10 to 36 hours, or 12 to 24 hours. For example, in particular embodiments, the drying time is about 24 hours. However, a separate drying operation is not necessary in all cases; in some embodiments, volatiles of the supernatant and / or aqueous washing liquids evaporate at a beginning stage of the calcining.

[0067] As noted above, process further includes calcining the precipitate to provide the Fischer-Tropsch catalyst material. The calcining step will generally convert various metallic species to oxide forms. In some embodiments of the present disclosure as described herein, calcining the precipitate is conducted for a calcining time and at a calcining temperature. For example, in some embodiments, the calcining time is in the range of 0.5 to 24 hours, or 0.5 to 15 hours, or 0.5 to 10 hours, or 0.5 to 5 hours. In some embodiments, the calcining temperature is in the range of 100-600 °C, e.g., in the range of 200-600 °C, or 300-600 °C, or 100-500 °C, or 200-500 °C, or 300-500 °C.

[0068] Addition of the potassium ions to the substantially alkali-free precipitate can be performed at any convenient time. For example, a small amount of an potassium ioncontaining liquid (e.g., an aqueous solution of potassium carbonate, potassium hydroxide, potassium acetate or potassium nitrate) can be added to the isolated (and optionally washed) precipitate; the person of ordinary skill in the art will appreciate that techniques like incipient wetness can be used. The precipitate can then be calcined to provide the Fischer-Tropsch catalyst material. In another embodiment, the isolated precipitate can first be calcined, then potassium added and the material calcined again to provide the potassium in oxidic form.

[0069] The person of ordinary skill in the art can use similar techniques to provide materials that include copper and / or manganese. It is noted that in many cases, copper and manganese can precipitate together with the iron. But impregnation can also be used to provide copper and / or manganese.

[0070] In other aspects, the present disclosure provides a Fischer-Tropsch catalyst as described herein made by a process as described herein.

[0071] Carbided Fischer-Tropsch Catalyst Material

[0072] Another aspect of the present disclosure provides a carbided Fischer-Tropsch catalyst material. The active species in iron-based Fischer Tropsch synthesis are generally understood to be carbide species. Thus, in some embodiments as described herein, the carbided Fischer-Tropsch catalyst material is the Fischer-Tropsch catalyst material as described herein, or a Fischer-Tropsch catalyst material made by a method as described herein, in a carbided form. In the carbided form, at least some of the iron included in the Fischer-Tropsch catalyst material is in the form of iron carbide.

[0073] Accordingly, another aspect of the disclosure is a carbided Fischer-Tropsch catalyst material comprising at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10, wherein at least 50 atom% of the iron of the carbided Fischer-Tropsch catalyst material is in the form of iron carbide.Such materials can be made, e.g., by the carbiding of the Fischer-Tropsch catalyst materials described herein. In various embodiments, the carbided Fischer-Tropsch catalyst materials can also include copper, in a molar ratio of copper to iron in the range up to 0.12.

[0074] It can be desirable to have a substantial fraction of the iron of the carbided Fischer-Tropsch catalyst material in carbide form, as it is carbide forms that are of highest catalytic activity. For example, in various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, at least 60 atom% of the iron is in a carbide form, e.g., at least 70 atom%, or at least 80 atom%, or at least 90 atom%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 50-99 atom% of the iron is in a carbide form, e.g., in the range of 50-95%, or 50-90%, or 50-85%. Invarious embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 60-99 atom% of the iron is in a carbide form, e.g., in the range of 60-95%, or 60-90%, or 60-85%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 70-99 atom% of the iron is in a carbide form, e.g., in the range of 70-95%, or 70-90%. In various embodiments of the carbided Fischer- Tropsch catalyst materials of the disclosure, in the range of 80-99 atom% of the iron is in a carbide form, e.g., in the range of 80-95%, or 80-90%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 90-99 atom% of the iron is in a carbide form, e.g., in the range of 90-98%, or 90-95%. The amount of iron that is in the form of carbide is determined by Mbssbauer spectroscopy, and as such is expressed as an atomic fraction of iron in the form of carbide of the total iron species visible to Mbssbauer spectroscopy.

[0075] The present inventors note that oxidic iron forms are generally not active catalysts for Fischer-Tropsch synthesis. Accordingly, in various embodiments, it can be desirable to provide a carbided Fischer-Tropsch catalyst material with relatively low amounts of iron in oxidic form. For example, in various embodiments, the carbided Fischer-Tropsch catalyst materials described herein have no more than 20 atom% of iron in oxidic form, e.g., no more than 10 atom%, or no more than 5 atom%, or no more than 2 atom%. The amount of iron that is in the form of oxide is determined by Mbssbauer spectroscopy, and as such is expressed as an atomic fraction of iron in the form of oxide of the total iron species visible to Mbssbauer spectroscopy. The person of ordinary skill in the art can, based on the disclosure herein, select reduction and carbiding conditions to provide a low degree of oxidic iron in the carbided Fischer-Tropsch catalyst materials of the disclosure.

[0076] For example, the present inventors note that oxidic carbon can catalyze water- gas shift reactions. In cases where the feed to the Fischer-Tropsch synthesis has relatively low amounts of carbon dioxide, there is often no desire for water-gas shift activity, and so oxidic carbon can be minimized. Accordingly, in various embodiments (e.g., in which the CO2 / CO ratio of the feed to a Fischer-Tropsch synthesis process is no more than 0.5 (e.g., no more than 0.2)), no more than 20 atom% of iron of the carbided Fischer-Tropsch catalyst material is in oxidic form, e.g., no more than 10 atom%, or no more than 5 atom%, or no more than 2 atom%.

[0077] However, the present inventors have determined that it in some cases it can be desirable to retain some degree of oxidic iron in the carbided Fischer-Tropsch catalyst material. Accordingly, in in various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, at least 5 atom% of the iron is in an oxide phase, e.g., at least 10 atom%, or at least 15 atom%, or at least 20 atom%. In various embodiments of the carbidedFischer-Tropsch catalyst materials of the disclosure, in the range of 5-50 atom% of the iron is in an oxide phase, e.g., 5-45 atom%, or 5-40 atom%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 10-50 atom% of the iron is in an oxide phase, e.g., 10-45 atom%, or 10-40 atom%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 15-50 atom% of the iron is in an oxide phase, e.g., 15-45 atom%, or 15-40 atom%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 20-50 atom% of the iron is in an oxide phase, e.g., 20-45 atom%, or 20-40 atom%. In cases where the feed to the Fischer-Tropsch synthesis reaction has relatively high amounts of carbon dioxide, there is often a desire for water-gas shift activity, such that the reverse water-gas shift reaction can convert CO2 to CO for use in the Fischer-Tropsch synthesis. Accordingly, in various embodiments in which the CO2 / CO ratio is in excess of 0.5, e.g., in excess of 1, amounts of oxide phase as described here can be used.

[0078] The amounts of iron, silicon, copper, potassium, and, manganese, as well as amounts of lithium and silver in the carbided Fischer-Tropsch catalyst materials can be substantially as described above.

[0079] In some embodiments as described herein, the carbided Fischer-Tropsch catalyst material is an unsupported catalyst material. As such, in some embodiments as described herein, at least 90 wt% of the carbided Fischer-Tropsch catalyst material is made up of iron, silica, copper (if present), and potassium, and, if present, manganese, as determined by ICP on an elemental basis exclusive of carbon. For example, in various embodiments as described herein, at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.5 wt%, or at least 99.8 wt% of the carbided Fischer-Tropsch catalyst material is made up of silica, and potassium, and, if present, manganese, on an elemental basis exclusive of carbon.

[0080] The person of ordinary skill in the art will appreciate that the carbided Fischer- Tropsch catalyst materials of the disclosure can be provided in many forms, depending especially on the particular form of the reactor system in which they are to be used, e.g., in a fixed bed reactor, a fluid bed reactor, a bubble column reactor, a so-called CANS reactor.

[0081] Notably, the present inventors have determined that especially desirable carbided Fischer-Tropsch catalyst materials have a high degree of x-Fe5C2. The present inventors have noted that such materials can be made by carbiding at relatively high temperatures, as described herein. The present inventors have determined that, surprisingly, carbided Fischer-Tropsch catalyst materials having high amounts of crystalline x-Fe5C2 provide a significantly lower selectivity for oxygenated hydrocarbons and CO2 than that typically provided by iron-catalyzed Fischer-Tropsch processes. However, the Fischer-Tropschcatalyst materials described herein can often still provide similar performance (i.e., CO2 conversion and C5+ hydrocarbon selectivity) when carbided at a low temperature (e.g., 180 °C) but subjected to Fischer-Tropsch synthesis conditions at higher temperature. Without intending to be bound by theory, the present inventors believe that the increased temperature of the CO2 Fischer-Tropsch conditions (e.g., when at least about 300 °C), transforms iron carbide formed during low temperature carbiding (i.e., e-Fe3C and r|-Fe2C) into x-Fe5C2.

[0082] Accordingly, in various embodiments as described herein, the carbided Fischer- Tropsch catalyst material comprises x-FesC2. In various embodiments, at least 50 atom% of the carbided iron of the carbided Fischer-Tropsch catalyst material is in the form of x-Fe5C2, e.g., at least 60 wt%, or at least 70 wt%. In various embodiments, at least 75 atom% of the carbided iron of the carbided Fischer-Tropsch catalyst material is in the form of x-Fe5C2, e.g., at least 80 wt%. In various embodiments, at least 85 atom% of the carbided iron of the carbided Fischer-Tropsch catalyst material is in the form of x-FesC2, e.g., at least 90 wt%. The state of the iron in the carbided Fischer-Tropsch catalyst material is determined by Mbssbauer spectroscopy as described above.

[0083] Processes for Carbiding

[0084] The carbided Fischer-Tropsch catalyst materials of the disclosure can be prepared by carbiding various Fischer-Tropsch catalyst materials described herein.

[0085] Accordingly, another aspect of the disclosure is a process for carbided Fischer- Tropsch catalyst material as described herein. The process comprises carbiding the Fischer-Tropsch catalyst material to provide the carbided Fischer-Tropsch catalyst material.

[0086] The carbiding can be performed in any convenient manner. Conventionally, iron- containing Fischer-Tropsch catalyst materials are prepared for use as active Fischer- Tropsch catalysts by treating them in situ with a reducing gas such as hydrogen, under conditions sufficient to convert a substantial amount of the iron oxides of the calcined Fischer-Tropsch catalyst material to metallic iron. Then, when exposed to Fischer-Tropsch reaction conditions, a substantial part of this iron is converted to carbide by carbon monoxide of the Fischer-Tropsch feed. It is thus not conventionally necessary to provide a separate carbiding treatment; rather, the carbiding is a natural result of Fischer-Tropsch reaction conditions. However, such Fischer-Tropsch processes tend to exhibit longer induction periods and a relatively higher degree of water-gas shift activity, especially at moderate Fischer-Tropsch reaction temperatures. This results in a relatively lower conversion of carbon monoxide to desirable C5+ products. Without intending to be bound by theory, the present inventors believe that this could result from incomplete carbide formation, such thatthere is still partially reduced or in an oxidic form. Nonetheless, the materials of the disclosure can be useful in such in situ carbiding methods.

[0087] The Fischer-Tropsch catalyst materials of the disclosure can be especially advantageous in such in situ carbiding methods, i.e., when carbiding is performed via exposure Fischer-Tropsch reaction conditions, when the Fischer-Tropsch reaction is performed at temperatures of at least 300 °C, e.g., at least 325 °C, or at least 350 °C. At such temperatures, the in situ carbiding can provide a high degree of carbide in the form of X-Fe5C2, e.g., to provide a carbided Fisher-Tropsch catalyst material of the disclosure for use in the Fischer-Tropsch synthesis.

[0088] However, the present inventors note that catalysts with a high degree of carbide in the form of x-FesC2 can be especially desirable for use in FT processes conducted at temperatures below 300 C in order to provide higher C5+ selectivity, and so it can be especially desirable to carbide at high temperature in a separate operation as otherwise described herein.

[0089] Another aspect of the disclosure is a process for making a carbided Fischer- Tropsch catalyst material as described herein. The process comprises carbiding the Fischer-Tropsch catalyst material to provide the carbided Fischer-Tropsch catalyst material.

[0090] The carbiding can be performed in any convenient manner. For example, in various embodiments, the carbiding includes a reduction step, in which the Fischer-Tropsch catalyst material is treated with a reducing gas stream (e.g., containing hydrogen) for a time and at a temperature sufficient to provide at least 50 atom% of the catalyst in metallic form. Without intending to be bound by theory, the inventors understand this step to reduce oxidic iron species to metallic iron species, so that they can be more easily carbided in a subsequent treatment with a carbiding gas. Upon treatment with the reducing gas stream, a portion of the iron components present in the Fischer-Tropsch catalyst material as described herein react to metallic iron (Fe°).

[0091] In various embodiments, the treatment with the reducing gas stream is performed in the substantial absence of carbon monoxide. For example, in various embodiments, the reducing gas stream comprises no more than 1 vol% carbon monoxide, e.g., no more than 0.5 vol%, or no more than 0.1 vol%, or no more than 0.05 vol%, or no more than 0.01 vol% carbon monoxide. In some embodiments as described herein, the reducing gas stream further comprises an inert gas. For example, in some embodiments, the inert gas is nitrogen. In some embodiments as described herein, the hydrogen and inert gas are present in the reducing gas stream in a ratio of at least 1 :1.

[0092] In various embodiments, treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a temperature in the range of 250-650 °C. For example, in various embodiments as described herein, treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a temperature in the range of 250-600 °C, or 250-550 °C, or 250-500 °C. In various embodiments as described herein, treating the Fischer-Tropsch catalyst material with the Fischer-Tropsch reducing gas stream is conducted at a temperature in the range of 300-650 °C, or 300-600 °C, or 300-550 °C, or 300-500 °C. In various embodiments as described herein, treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a temperature in the range of 350-650 °C, or 350-600 °C, or 350-550 °C, or 350-500 °C.

[0093] In various embodiments, the treatment with the reducing gas stream is performed at a pressure within 10 bar of atmospheric pressure, e.g., within 7 bar of atmospheric pressure, or within 5 bar of atmospheric pressure.

[0094] As described above, treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted for a time sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in metallic form. In various embodiments, treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted for at least 12 hours, e.g., at least 14 hours. For example, in various embodiments as described herein, treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted for a time in the range of 12 to 30 hours, e.g., in the range of 12 to 24 hours, or 14 to 30 hours, or 14 to 24 hours.

[0095] The person of ordinary skill in the art will be able to determine appropriate reducing conditions to provide a Fischer-Tropsch catalyst material with at least 50 atom% iron in reduced form. While the paragraphs above provide guidance for reducing gas streams, temperatures and times, the person of ordinary skill in the art will be able to, based on the present disclosure, provide suitable reduction conditions to provide a substantially reduced Fischer-Tropsch catalyst material. In various embodiments, the treatment with the reducing gas stream is performed to provide a Fischer-Tropsch catalyst material in which at least 60 atom% of the iron is in reduced form, e.g., at least 70 atom%. In various embodiments, the treatment with the reducing gas stream is performed to provide a Fischer- Tropsch catalyst material in which at least 80 atom% of the iron is in reduced form, e.g., at least 85 atom%. The proportion of iron in reduced form is measured by XRD.

[0096] Moreover, the present inventors note that in some cases a pre-reduction step may not be necessary, as there will often be hydrogen present during the carbiding, and that hydrogen can reduce iron to metallic iron which can be subsequently converted to carbide.Accordingly, in some embodiments, the Fischer-Tropsch catalyst material is in oxidic form when treated with the carbiding gas stream; in such embodiments, the treatment with the carbiding gas stream is desirably performed in the presence of hydrogen.

[0097] The carbiding can include treating the Fischer-Tropsch catalyst material with a carbiding gas stream comprising carbon monoxide and or carbon dioxide (e.g., carbon monoxide), at a temperature of at least 180 °C for a time sufficient to provide at least 50 atom% of the iron of the carbided Fischer-Tropsch catalyst material in carbided form. This can be performed, e.g., after a treatment with a reducing gas as described above, or, in cases where hydrogen is present in the carbiding gas stream, on a Fischer-Tropsch catalyst material in substantially oxidic form.

[0098] The present inventors have determined in particular that catalyst carbiding can be performed in such a manner so as to reduce the water-gas shift activity of the catalyst and thereby reduce CO2 selectivity and increase C5+ selectivity. Thus, not only can the properties of the as-calcined catalyst material (e.g., relative amounts of metallic constituents) and the Fischer-Tropsch reaction parameters (e.g., temperature, GHSV, H2 / CO ratio) affect selectivity of the active Fischer-Tropsch catalyst material, so too can the conditions under which the Fischer-Tropsch catalyst material is activated by carbiding. The present inventors have determined that, the carbiding conditions themselves can be varied to provide particular desirable activity in the Fischer-Tropsch synthesis. Thus, while the compositions of the disclosure can be useful even when carbided under different conditions, in various embodiments, the Fischer-Tropsch catalyst materials of the disclosure are carbided as described herein.

[0099] In various embodiments, the Fischer-Tropsch catalyst material is treated with a carbon monoxide and / or carbon dioxide-containing gas (e.g., carbon monoxide-containing gas) to provide the carbided Fischer-Tropsch catalyst material. In various embodiments, the carbiding gas stream comprises carbon monoxide. However, the present inventors note that in some cases carbon dioxide may be suitable for providing carbon for carbiding; without intending to be bound by theory the present inventors surmise that the high water-gas shift activity of iron e.g., in oxide form) can cause carbon dioxide, in the presence of hydrogen, to be converted via the reverse water-gas shift reaction to carbon monoxide, which can be the active carbiding species.

[0100] The present inventors have found that carbiding conditions can significantly affect the activity of the carbided Fischer-Tropsch catalyst material in use. The present inventors have determined that, despite the fact that carbon monoxide and / or carbon dioxide (e.g., carbon monoxide) is the species providing the carbon for the carbiding, it can beadvantageous to use a significant amount of hydrogen in the carbiding gas stream. Thus, in various embodiments, the carbiding gas stream includes hydrogen in addition to carbon monoxide and / or carbon dioxide. For example, in some embodiments as described herein, the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of at least 1:1 hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide). For example, in various embodiments, the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide) of at least 2:1, or at least 5:1, or at least 10:1 , or at least 15:1, or at least 20:1 , or at least 25:1, or at least 30:1. In some embodiments as described herein, the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide) of 1:1 to 100:1 , e.g., in the range of 2:1 to 100:1, or 5:1 to 100:1, or 10:1 to 100:1 , or 15:1 to 100:1, or 20:1 to 100:1 , or 25:1 to 100:1 , or 30:1 to 100:1. In some embodiments as described herein, the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide) of 1:1 to 50:1 , e.g., in the range of 2:1 to 50:1, or 5:1 to 50:1, or 10:1 to 50:1 , or 15:1 to 50:1, or 20:1 to 50:1 , or 25:1 to 50:1 , or 30:1 to 50:1. In various embodiments in which hydrogen is provided together with the carbon monoxide and / or carbon dioxide in the carbiding gas, it may not be necessary to perform a separate reduction step beforehand; hydrogen in the carbiding gas can reduce the oxidic iron to metallic iron, which can then be carbided by the carbon monoxide / carbon dioxide present.

[0101] As described above, treating the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted at a temperature of at least 180 °C. For example, in various embodiments, treating the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted at a temperature of at least 200 °C, e.g., at least 220 °C. For example, in various embodiments, treating the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 180-450 °C (e.g., in the range of 180- 400 °C, or 180-350 °C, or 180-300 °C). In various embodiments, treating the Fischer- Tropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 200-450 °C (e.g., in the range of 200-400 °C, or 200-350 °C, or 200-300 °C). In various embodiments, treating the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 220-450 °C (e.g., in the range of 220- 400 °C, or 220-350 °C, or 220-300 °C). Without intending to be bound by theory, it is believed that carbiding at lower temperatures provides carbided Fischer-Tropsch materials having a high proportion of carbide in the e-FesC and r|-Fe2C forms. Such materials arebelieved to be useful catalyst materials, albeit with lower selectivity to olefins and higher selectivity to oxygenated hydrocarbons and carbon dioxide.

[0102] The present inventors have found that carbiding temperature has a significant effect on the activity of the carbided Fischer-T ropsch catalyst under Fischer-T ropsch reaction conditions. For example, the present inventors have found that carbiding at relatively high temperatures can provide a carbided Fischer-T ropsch catalyst material with high selectivity for C5+ hydrocarbons, with an increased proportion of olefins. The present inventors have noted, unexpectedly, that high temperature carbiding can provide catalysts with high amounts of x-FesC2. The person of ordinary skill in the art can determine, based on the present disclosure, carbiding conditions suitable to provide a carbided Fischer- Tropsch catalyst material having a high degree of x-Fe5C2, for example, in proportions as described above.

[0103] Accordingly, in various embodiments, treating the Fischer-T ropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of at least 300 °C, e.g., at least 310 °C, or at least 325 °C, or at least 350 °C, or at least 375 °C, or at least 400 °C. For example, in various embodiments as described herein, treating the Fischer-T ropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 300-650 °C, e.g., 300-600 °C, or 300-550 °C or 300-500 °C. For example, in various embodiments as described herein, treating the Fischer-T ropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 310-650 °C, e.g., 310-600 °C, or 310-550 °C, or 310-500 °C. In various embodiments as described herein, treating the Fischer-T ropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 325-650 °C, e.g., 325-600 °C, or 325-550 °C, or 325-500 °C. In various embodiments as described herein, treating the Fischer-T ropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 350-650 °C, e.g., 350-600 °C, or 350-550 °C, or 350-500 °C. In various embodiments as described herein, treating the Fischer-T ropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 375-650 °C, e.g., 375-600 °C, or 375-550 °C, or 375-500 °C. In some embodiments as described herein, treating the Fischer-T ropsch catalyst material with a carbiding gas stream is conducted at a temperature in the range of 400-650 °C, e.g., 400- 600 °C, or 400-550 °C, or 400-500 °C.

[0104] Moreover, even when a Fischer-T ropsch catalyst material is initially carbided under lower temperature conditions to form e-Fe3C and r|-Fe2C, it can, under some high- temperature Fischer-T ropsch reaction conditions, convert to x-Fe5C2. This may require a significant induction period under Fischer-T ropsch reaction conditions, but is nonetheless contemplated as a way to make carbided materials with high amounts of x-FesC2.Moreover, in such high-temperature Fischer-Tropsch processes C5+ selectivity can suffer due to the formation of relatively more C1-C4 hydrocarbons; accordingly, it may often be desirable to perform a separate high-temperature carbiding and operate the Fischer-Tropsch synthesis itself at lower temperatures (e.g., below 300 °C).

[0105] In various embodiments, the carbiding is performed at a pressure within 10 bar of atmospheric pressure, e.g., within 7 bar of atmospheric pressure, or within 5 bar of atmospheric pressure.

[0106] As described above, treating the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted for a time sufficient to provide at least 50 atom% of the iron of the carbided Fischer-Tropsch catalyst material in carbided form. For example, in various embodiments, the treating of the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted for a time of at least 3 hours, e.g., at least 5 hours. In various embodiments, the treating of the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted for a time in the range of 3-20 hours, e.g., 5-20 hours, or 3-15 hours, or 5-15 hours.

[0107] Fischer-Tropsch Processes

[0108] Another aspect of the present disclosure provides a process for performing a Fischer-Tropsch synthesis reaction. The process includes providing a carbided Fischer- Tropsch catalyst material as described herein, and contacting at a reaction temperature and pressure the Fischer-Tropsch catalyst with a feed stream comprising H2 and CO to provide a product stream comprising C5+ hydrocarbons. An example of such a process is shown schematically in FIG. 1. In FIG. 1, the process 100 includes contacting at a temperature and at a pressure a carbided Fischer-Tropsch catalyst material as described herein with a feed stream comprising H2and CO to provide a product stream comprising C5+ hydrocarbons. In the process 100 of FIG. 1 , the feed stream 121, which is contacted with Fischer-Tropsch catalyst material 123, here, in a reaction zone (e.g., a reactor 120). This provides a product stream 122, which includes C5+ hydrocarbons. Notably, the carbided Fischer-Tropsch catalyst material can be provided by a separate carbiding operation, or rather can be carbided in situ under the Fischer-Tropsch reaction conditions.

[0109] H2and CO can be provided to the feed stream from a variety of sources. The person of ordinary skill in the art will appreciate that H2can be provided from a variety of sources, e.g., gasification, reforming, or H2O electrolysis. Moreover, as described in more detail below, H2can be recycled to the feed stream from the product stream. Carbon monoxide from a variety of sources, such as fossil-based sources (e.g., natural gas), may be utilized in admixture with the streams as described herein. In various embodiments asotherwise described herein, the process further comprises providing carbon monoxide from a fossil source in the H2 / CO stream. In some embodiments, the person of ordinary skill in the art can provide CO by reacting CO2in a reverse water-gas shift reaction; excess hydrogen can be input to such a process, so that the output of the reverse water-gas shift reaction can include both CO and H2to be provided to the feed stream.

[0110] As described above, CO and H2are substantial inputs to the claimed processes. Advantageously, the present inventors have recognized that each of these can come from renewable or otherwise environmentally responsible sources.

[0111] For example, H2can be provided from environmentally-responsible sources. In some embodiments, at least a part of the H2of the feed stream is from a renewable source. For example, in various embodiments, at least part (e.g., at least 25%, at least 50%, or at least 75%) of the H2of the feed stream can be so-called “green” hydrogen, e.g., produced from the electrolysis of water operated using renewable electricity (such as wind, solar, or hydro-electric power). In some embodiments, at least part (e.g., at least 25%, at least 50%, or at least 75%) of the H2of the feed stream may be from a so-called “blue” source, e.g., from a natural gas reforming process with carbon capture. Of course, other sources of H2can be used in part or in full. For example, in some embodiments, at least part (e.g., at least 25%, at least 50%, or at least 75%) of the H2of the feed stream is grey hydrogen, black hydrogen, brown hydrogen, pink hydrogen, turquoise hydrogen, yellow hydrogen, and / or white hydrogen.

[0112] The present inventors have noted that electrolysis of water can be a desirable way to provide hydrogen to the claimed processes. Accordingly, in some embodiments, the process includes providing at least a portion of H2to the feed stream by electrolysis of water. In some embodiments, the electrolysis of water is performed using at least partially electricity from a renewable source, e.g., to provide so-called “green hydrogen.” However, the present inventors have noted that electricity can be generated as part of the claimed process, e.g., using heat exchange from the first or second product stream, or by burning light hydrocarbons as described above. In some embodiments, the electrolysis of water is performed using at least partially electricity generated according to the processes as described herein. In some embodiments, at least a portion of O2generated in the electrolysis is provided to a partial oxidation reaction zone as described herein.

[0113] As described above, the feed stream contains both H2and CO and the feed stream includes all feeds to the Fischer Tropsch reactor, regardless of whether the feed stream is provided as a mixture of feeds or as feeds provided individually to a reaction zone. In various embodiments of the present disclosure as described herein, the feed stream has aH2:CO ratio in the range of 0.5:1 to 6:1. In some embodiments, the feed stream has a H2:CO ratio in the range of 1 :1 to 3:1, or 1 :1 to 2.5:1. In some embodiments, the feed stream has a H2:CO ratio of at least 1.4:1. For example, in some embodiments, the feed stream has a H2:CO ratio in the range of 1.4:1 to 3:1, or 1.4:1 to 2:1. The person of ordinary skill in the art will provide a desired ratio of H2:CO in the feed stream, based on the disclosure herein that provides a desirable conversion and selectivity in the Fischer-Tropsch process.

[0114] Other gases may also be included in the feed stream. For example, it can be desirable to perform the Fischer-Tropsch process step in the presence of a significant amount of inerts (i.e., components that are not H2or CO). For example, in various embodiments, the feed stream includes up to 80 mol% of one or more inerts, e.g., in the range of 3-80 mol%, or 5-80 mol%, or 10-80 mol%, or 15-80 mol%, or 30-80 mol% of one or more inerts. In various embodiments, the feed stream includes up to 70 mol% inerts, up to 60 mol% inerts, or up to 50 mol% inerts, e.g., 3-70 mol%, or 5-70 mol%, or 10-70 mol%, or 15-70 mol%, or 30-70 mol%, or 3-60 mol%, or 5-60 mol%, or 10-60 mol%, or 15-60 mol%, or 30-60 mol%, or 3-50 mol%, or 5-50 mol%, or 10-50 mol%, or 15-50 mol%, or 30-50 mol% inerts. In various embodiments, the feed stream includes up to 80% of one or more inerts selected from methane and nitrogen, e.g., up to 70 mol%, up to 60 mol%, or up to 50 mol%, or 15-70 mol%, or 30-70 mol%, or 15-60 mol%, or 30-60 mol%, or 15-50 mol%, or 30-50 mol%.

[0115] To reduce WGS activity, it can be desirable to have CO2present in the feed stream; as the water-gas shift is generally an equilibrium process, the presence of CO2helps to disfavor the conversion of CO to CO2. In various embodiments, the feed stream includes up to 80 mol% of CO2, e.g., up to 70 mol%, up to 60 mol%, or up to 50 mol%, or 15-70 mol%, or 30-70 mol%, or 15-60 mol%, or 30-60 mol%, or 15-50 mol%, or 30-50 mol%. In various embodiments, the molar ratio of CO2to CO in the feed stream is at least 0.5:1 , e.g., at least 0.7:1 or at least 1:1. However, catalysts of the disclosure can also be used in cases where the molar ratio of CO2to CO in the feed stream is no more than 0.5, e.g., no more than 0.3.

[0116] Similarly, to reduce WGS activity, it can be desirable to reduce the amount of water that is conducted to the Fischer-Tropsch process step. Accordingly, in various embodiments as otherwise described herein, the feed stream has a water content of no more than 10 mol%, e.g., or no more than 2 mol%, or no more than 0.5 mol%. Maintaining a low amount of water can have additional benefits, such as improving catalyst stability.

[0117] The Fischer-Tropsch catalyst materials as described herein are suitable for use in the Fischer-Tropsch processes described herein. The person of ordinary skill in the art will appreciate that the Fischer-Tropsch catalyst materials of the disclosure can be provided in many forms, depending especially on the particular form of the reactor system in which they are to be used, e.g., in a fixed bed or as a fluidized bed. The person of ordinary skill in the art will select an appropriate form of the Fischer-Tropsch catalyst material for the particular reactor system.

[0118] For example, in various embodiments, the Fischer-Tropsch catalyst material is first reduced by contact with a reducing gas. For example, hydrogen can be an especially suitable gas for activating the Fischer-Tropsch catalyst material, e.g., when the activation includes a reduction to metal(O) species. In various embodiments of the present disclosure as otherwise described herein, the feed stream and the reaction conditions in the Fischer- Tropsch reaction system can be adjusted to provide desired reduction conditions. In the process 200 shown schematically in FIG. 2, the feed stream 221 is adjusted appropriately and contacted with the Fischer-Tropsch catalyst 223 under appropriate reduction reaction conditions in reaction zone 220 to reduce it. The reduction can be performed, e.g., as described above. [

[0119] In various embodiments, and as described above, the reduced Fischer-Tropsch catalyst material can be carbided by contact with CO and / or CO2. Here, too, the feed stream can be adjusted to provide a desired amount of CO and / or CO2, and reaction conditions in the reactor can be suitably modified to provide for carbidization of the Fischer-Tropsch catalyst material, as described above. In the process 200 shown schematically in FIG. 2, the feed stream 221 is adjusted appropriately and contacted with the Fischer-Tropsch catalyst material 223 in reaction zone 220 to carbide it. Carbidization can be performed, e.g., as described above.

[0120] However, separate carbiding processes are not necessary, as the Fischer- Tropsch catalyst material can be carbided under the Fischer-Tropsch reaction conditions, especially when treated first with a reducing gas as described above.

[0121] As described above, the process includes contacting at a temperature and at a pressure the carbided Fischer-Tropsch catalyst material with a feed stream. The person of ordinary skill in the art will select appropriate reaction conditions in conjunction with the particular feed and catalyst used to provide desired Fischer-Tropsch processes. In some embodiments of the disclosure as described herein, the reaction temperature is in the range of 150-400 °C. For example, in various embodiments, the reaction temperature is in the range of 150-350 °C, or 150-300 °C, or 150-250°C, or 150-200°C, or 200-400 °C, or 200-350°C, or 200-300°C, or 200-250 °C, or 250-400 °C, or 250-350 °C, or 250-300 °C, or 300-400 °C. In some particular embodiments, the temperature is in the range of 200-350 °C. In other particular embodiments, the reaction temperature is in the range of the reaction temperature is in the range of 180-250 °C, e.g., in the range of 190-250 °C, or 200-250 °C, or 210-250 °C, or 220-250 °C.

[0122] In some embodiments of the disclosure as described herein, the pressure is in the range of 10-50 barg. For example, in various embodiments, the pressure is in the range of 20-50 barg, or 25-50 barg, or 10-40 barg, or 20-40 barg, or 25-40 barg or 10-35 barg, or 20-35 barg, or 25-35 barg. In some embodiments, the pressure is in the range of 20-50 barg.

[0123] The Fischer-Tropsch processes described herein can be performed at a variety of GHSV (gas hourly space velocity) values, as would be appreciated by the person of ordinary skill in the art. As such, the GHSV for performing the Fischer-Tropsch reaction is not particularly limited. For example, in some embodiments of the present disclosure, the process for performing the Fischer-Tropsch reaction is conducted at a GHSV in the range of 1 ,000 to 2,000,000 h’1. In various embodiments, the process for performing the reverse water-gas shift reaction is conducted at a GHSV in the range of 1 ,000 to 1 ,200,000 IT1, or 1 ,000 to 500,000 IT1, or 1 ,000 to 100,000 IT1, or 5,000 to 1 ,200,000 IT1, or 5,000 to 500,000 IT1, or 5,000 to 100,000 IT1, or 10,000 to 1 ,200,000 IT1, or 10, 000 to 500,000 IT1, or 10, 000 to 100,000 IT1. In various embodiments of the present disclose, the process for performing the Fischer-Tropsch reaction is conducted at a GHSV in the range of 1 ,000 to 50,000 IT1, or2,000 to 50,000 IT1, or 5,000 to 50,000 IT1, or 10, 000 to 50,000, or 1 ,000 to 40,000 IT1, or2,000 to 40,000 IT1, or 5,000 to 40,000 IT1, or 10, 000 to 40,000 IT1, or 1 ,000 to 30,000 IT1, or2,000 to 30,000 IT1, or 5,000 to 30,000 IT1, or 10,000 to 30,000 IT1. The person of ordinary skill in the art will appreciate that all such ranges of space velocities may not be available for any given process.

[0124] The Fischer-Tropsch process is typically used to make C5+ hydrocarbons, for example, unsubstituted C5+ hydrocarbons (e.g., alkanes and alkenes) and oxygenated C5+ hydrocarbons (e.g., C5+ alcohols, aldehydes, ketones, carboxylic acids). In various embodiments of the disclosure as described herein, contacting the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C5+ selectivity (i.e. , for all C5+ species) of at least 30%, e.g., at least 40%, or at least 50%. For example, in some embodiments, the selectivity for C5+ alkanes is at least 30%, e.g., at least 40%, or at least 50%. In some embodiments, contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C5+ selectivity of at least 60%, e.g., at least 70%, or at least 80%. In some embodiments, contacting of the Fischer-Tropsch catalyst withthe feed stream to provide the product stream is performed with a C2-4 selectivity of no more than 30%, e.g., no more than 25%, or no more than 20%. In some embodiments, the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a methane selectivity of no more than 20%, e.g., no more than 15%, or no more than 10%, or no more than 5%. In some embodiments, contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C2-8 oxygenate selectivity of no more than 30%, e.g., no more than 25%, or no more than 20%. In some embodiments, contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C2-8 oxygenate selectivity of no more than 15%, e.g., no more than 10%, or no more than 5%.

[0125] Additional components may be in present in the product stream. For example, in some embodiments, the product stream includes water, which is another product of the Fischer-Tropsch reaction. Also present can be one or more light hydrocarbons (i.e. , C1-C4) as a side product. CO and / or H2 can be present, e.g., unreacted from the feed stream. CO2 or other inerts as described herein can also be present. Such components of the product stream can be separated and / or recycled in various manners.

[0126] For example, in various embodiments, the process further comprises separating at least a portion of water from the product stream. This is shown schematically in FIG. 3. In the embodiment of FIG. 3, reaction zone 320 is a volume of the reactor 305 that includes the bed 324 containing the carbided Fischer-Tropsch catalyst material 323. The feed stream 321 is passed to the carbided Fischer-Tropsch catalyst material 323 to provide second product stream 322. Here, the process also optionally includes separating at least a portion of water (e.g., at least 50%, at least 75%, or at least 90%) from the product stream 322 to provide water-containing stream 334.

[0127] Light hydrocarbons, while often not a desired portion of a Fischer-Tropsch product to be used as a fuel or a lubricant, can themselves be useful for a number of purposes. Accordingly, in various embodiments, the process further includes separating at least a portion of C1-C4 hydrocarbons from the second product stream to provide a light hydrocarbon stream. The light hydrocarbon stream can, for example, be recycled to the first feed stream or the second feed stream. For example, in the process 200 of FIG. 2, light hydrocarbons from product stream 222 can be provided as part of the recycle stream 236, which becomes part of the feed stream 221. In the process 300 of FIG. 3, light hydrocarbons can be provided as part of the recycle stream 336, which becomes part of the feed stream 321. In the process 400 of FIG. 4, light hydrocarbons are recycled via recycle stream 442 to first feed stream 421.

[0128] There are other uses for the light hydrocarbon stream. For example, in some embodiments, the process further comprises oxidizing at least a portion of the light hydrocarbon stream to provide a CO- and / or CO2-containing partial oxidation (pOX) stream, and including at least a portion of the pOX stream in feed stream. An example of such a process is shown schematically in FIG. 4, in which the process 400, the feed stream 421 , the product stream 422, the reaction zone 420, and the Fischer-Tropsch catalyst 423 can be as otherwise described herein. Here, the process includes oxidizing at least a portion of the light hydrocarbon stream 450, in a partial oxidation reaction zone 452 to provide a CO- and / or CO2 containing pOX stream, and including at least a portion of the pOX stream 454 stream in the feed stream 421.

[0129] Moreover, the light hydrocarbon stream can be burned to provide heat energy, which can be used to heat various process streams, or to generate electricity. Accordingly, in various embodiments, the process includes burning at least a portion of the light hydrocarbon stream to provide energy, e.g., heat energy or electrical energy. For example, in the process 400 of FIG. 4, a portion of light hydrocarbon stream 450 is burned in a power generation zone (here, in an electrical generator 470), to generate electricity stream 472. In various embodiments, the heat energy may be used to provide the needed heat duty for the Fischer-Tropsch process. For example, in the process 400 of FIG. 4, a portion of the light hydrocarbon stream 450 is burned in a power generation zone (here, in a heat generator 480), to generate heat stream 482. The heat stream 482 is conducted to a heat exchange zone 490 to heat the feed stream 421.

[0130] Heat can be exchanged from the product stream to provide heat to, for example, a feed stream or a steam generation zone. For example, in various embodiments, the process further comprises exchanging heat between at least a portion of the product stream and at least a portion of the feed stream, thereby cooling at least a portion of the product stream and heating at least a portion of the feed stream. In process 300 of FIG. 3, heat is exchanged between at least a portion of the product stream 322 and feed stream 321 in a second heat exchange zone 330, thereby cooling the product stream 322 and heating the feed stream 321. The person of ordinary skill in the art will appreciate that a wide variety of heat exchangers can be used for this purpose.

[0131] Of course, any excess heat in the product stream can be additionally or alternatively used for other purposes. For example, in various embodiments the process further comprises exchanging heat between at least a portion of the product stream and a steam generation zone, thereby cooling at least a portion of the product stream and providing heat to the steam generation zone. This is shown in FIG. 3. Here, after heatexchange with the feed stream 321, the product stream 322 is conducted to steam generation zone 332, to cool the product stream 322 and provide heat to the steam generation zone 332. Steam can be generated from the heat provided, and electricity can be generated from the steam (not shown here).

[0132] It can be desirable to recycle hydrogen from the product stream, for example, to the feed stream. For example, in various embodiments, the process includes recycling at least a portion of H2of the product stream to the feed stream. For example, in the process of FIG. 2, at least a portion of H2of the product stream (e.g., at least 25%, at least 50%, or at least 75%) can be recycled to the feed stream 221 via recycle stream 236.

[0133] Similarly, it can be desirable to recycle CO of the product stream, for example, to the feed stream. For example, in various embodiments, the process includes recycling at least a portion of CO of the product stream to the second feed stream. For example, in the process of FIG. 2, at least a portion of CO of the product stream (e.g., at least 25%, at least 50%, or at least 75%) can be recycled to the feed stream 221 via recycle stream 236.

[0134] In many cases, both CO and H2of the second product stream will be recycled.

[0135] Moreover, when one or more inerts are used in the Fischer-Tropsch process step, it can be desirable to recycle these. For example, in various embodiments, the process includes recycling at least a portion of inerts of the product stream to the feed stream. For example, in the process of FIG. 2, at least a portion of inerts of the product stream (e.g., at least 25%, at least 50%, or at least 75%) can be recycled to the feed stream 221 via recycle stream 236. In various embodiments, the process includes recycling at least a portion of inerts of the product stream to the feed stream. In various embodiments, a purge stream can be incorporated with the recycle stream to prevent uncontrolled accumulation of inerts in the recycle stream (not shown here).

[0136] As noted above, the Fischer-Tropsch process step provides a product stream that includes C5+ hydrocarbons (e.g., unsubstituted hydrocarbons like alkanes and alkenes, and / or oxygenated hydrocarbons such as alcohols). Accordingly, in various embodiments, one or more products are provided from at least a portion of C5+ hydrocarbons of the second product stream. The C5+ hydrocarbons can be used as the basis of a variety of fuels, e.g., gasoline, diesel, aviation fuel. Other products, like waxes and lubricants, can also be made. And alkenes and oxygenates can be used as feedstocks in a variety of other processes.

[0137] The person of ordinary skill in the art will use conventional post-processing techniques to convert the C5+ hydrocarbon-containing product to desirable products such as desirable fuels. For example, in various embodiments, the process further includeshydroprocessing at least a portion of C5+ hydrocarbons of the product stream. As the person of ordinary skill in the art will appreciate, hydroprocessing is a treatment of the hydrocarbon stream with hydrogen in the presence of a suitable catalyst. A wide variety of hydroprocessing techniques are known and the person of ordinary skill in the art will apply them here. For example, in the process 300 of FIG. 3, second product stream 322 is hydroprocessed in hydroprocessing reactor 350, to provide a hydroprocessed product stream 352.

[0138] The person of ordinary skill in the art will provide the materials and perform the processes described herein based on the general disclosure above, and with reference to the Examples below.EXAMPLES

[0139] The Examples that follow are illustrative of specific embodiments of the materials and process of the disclosure, and various uses thereof. They are set forth for explanatory purposes only, and are not to be taken as limiting the scope of the disclosure.Example 1 - Catalyst material preparation

[0140] In this first example of catalyst preparation, iron compounds are precipitated in the presence of potassium, with washing used to provide a desired low concentration of potassium. Here, a Fischer-Tropsch catalyst material with desired composition containing Fe, Si, Cu, and K was prepared using the following procedure. For some formulations, the amounts of Cu and K were varied.(1) Fe(NOs)3-9H2O and Cu(NOs)2-2.5H2O were first dissolved in deionized water under vigorous stirring to obtain solution A.(2) K2CO3 was dissolved in 1200 g of deionized water in a separate container under vigorous stirring to obtain solution B.(3) DI water was added into a vessel equipped with a mechanical stirrer, a heating mantel / temperature control system, and a condenser.(4) The temperature of the water in the vessel was increased to 80 °C, then the pH of the water was adjusted to 9 with the K2CO3 solution prepared above.(5) The solutions A and B were added simultaneously at roughly the same rate while monitoring the pH value of the slurry; adjusting it by changing flowrate of solution B.(6) After the precipitation, tetraethyl orthosilicate was weighed and slowly add into the slurry under vigorous stirring. The resultant precipitate was allowed to age under vigorous stirring (500 rpm) for 2h.(7) The alkali was washed out via repeated washing with DI water. This process can be accelerated by using hot water.(8) The catalyst particles were separated from the solution using a centrifuge or a filter(9) The above was repeated until desired residual level of alkali is obtained.(10) The solid was dried in ambient conditions overnight followed by drying in an oven at 110 °C overnight.(11) The solid was calcined in air flow at 300 °C for 4h, via a ramp of 2 °C / min to obtain a Fischer-Tropsch catalyst material in oxide form.Example 2 - Catalyst material preparation

[0141] In this second example of catalyst preparation, iron compounds are precipitated in the absence of potassium, with potassium added via impregnation of the dried precipitate, followed by a final drying and calcining. Here, a Fischer-Tropsch catalyst material with desired composition containing Fe, Si, Cu, and K was prepared using the following procedure. For some formulations, the amounts of Cu and K were varied.(1) Fe(NOs)3-9H2O was first dissolved in deionized water under vigorous stirring to obtain solution A.(2) Ammonium hydroxide (34%) was used as solution B.(3) DI water was added into a vessel equipped with a mechanical stirrer, a heating mantel / temperature control system and a condenser.(4) The temperature of the water in the vessel was increased to 80 °C, then the pH of the water was adjusted to 8.3 with the NH4OH solution.(5) The solutions A and B were added simultaneously at roughly the same rate while monitoring the pH value of the slurry; adjust it by changing flowrate of solution B.(6) After the precipitation, tetraethyl orthosilicate was weighed and slowly add into the slurry under vigorous stirring. Then let the resultant precipitate age under vigorous stirring (500 rpm) for 2h.(7) The catalyst particles were separated from the solution using a centrifuge or a filter(8) The solid was dried in ambient conditions overnight followed by drying in an oven at 110 °C overnight.(9) The solid was pulverised, then the powder loaded with desired amount of copper and alkali promoter via wet or incipient wetness impregnation. This step can be performed combined or sequentially. If performed sequentially, optionally after the first impregnation the material is dried and optionally subjected to calcination prior to the performing the second impregnation.(10) After the final impregnation step, the sample was dried in an oven at 110 °C overnight, then the solid calcined in air flow at 300 °C for 4h, via a ramp of 2 °C / min to obtain a Fischer-Tropsch catalyst material in oxide form.Example 3 - Catalyst carbiding and reaction testing

[0142] A variety of catalyst materials were prepared via either of the processes in described in Examples 1 and 2 above. Catalyst materials contained iron, silicon, copper and potassium, and were initially provided in as-calcined form (i.e. , in oxidic form). Catalyst materials were carbided and tested using the following general procedure: After an initial drying step using inert gas, a H2reduction near atmospheric pressure was performed at 400 °C for 16 h to substantially reduce all iron oxides to metallic Fe. Following the reduction, carbiding was performed near atmospheric pressure for 4-6 hours at 400°C with 3% CO (balance H2). After the carbiding step, the catalyst was cooled to <150 °C. Then, the gas composition was switched to syngas and the system pressurized to reaction pressure (30 bar), held for 1 h, and then ramped to reaction temperature at 2 °C / min. The catalysts are quick to reach stable performance, in contrast with the initiation period observed for the frequently-applied method of reducing and carbiding iron Fischer-Tropsch catalysts by exposing the oxidic material directly to syngas.

[0143] While not described in this set of experiments, similar performance of the carbided Fischer Tropsch catalyst materials is observed when carbiding is performed at 350 °C and 50% CO (balance H2). Applicants note that at higher carbiding temperatures, higher hydrogemcarbon monoxide ratios are generally preferred. But the optimal H2 / CO ratios can depend on the applied carbiding temperature, the catalyst type and factors such as alkali concentration level. The person of ordinary skill in the art can determine appropriate carbiding conditions based on the present disclosure.

[0144] Nineteen different catalysts were considered in this study. Molar ratios of silicon to iron ranged from 0.03-0.06, potassium:iron molar ratios ranged from -0.009-0.029, and copperiron molar ratios ranged up to 0.07. The prepared materials (i.e., in as-calcined form) exhibited high surface areas in the range of 70-250 m2 / g, and pore volumes of 0.21-0.5 mL / g. XRD characterization of the as-calcined catalysts detected ferrihydrite as the main iron phase.

[0145] Table 1 provides CO conversion and product selectivity data for six catalysts, all having surface areas ranging from 190-230 m2 / g and pore volume -0.3 cc / g. Reaction conditions were H2 / CO = 1.0 (40% inert), 245 °C, p 30 bar, GHSV -3000, after reduction in H2(400 °C) and carbiding in 3% CO (balance H2) at 400 °C (6 h). The “GHSV” is the hourly space velocity of only the syngas components CO and H2; 15-30% inert was also typically present in the feed gas stream. Reported hydrocarbon product selectivities are amongst all products (including CO2).Table 1

[0146] Despite the low syngas ratio and the elevated temperature of 245 °C — two factors that favor CO2 formation via water-gas shift and hence reduce the overall C5+ Sel% — only moderate CO2 selectivity (16-20%) resulted at CO conversion levels of 32-35%.Combined with the low methane selectivity, this allowed most products (53-61%) to be in the range of condensable hydrocarbons, which are valuable for further refining into finished products.

[0147] Table 2 provides for CO conversion and product selectivity data for the same six catalysts as Table! Reaction conditions were H2 / CO = 1.0, (40% inert) 245 °C, p~30 bar, GHSV -3000, after reduction in H2(400 °C) and treatment in syngas (H2 / CO = 1.8, 180 °C). Reported hydrocarbon product selectivities are amongst all products (including CO2).Table 2

[0148] In contrast to the high-temperature carbiding, simply treating the reduced catalysts in syngas during the startup (180 °C) and initial conditioning period resulted in comparable activity (in terms of similar CO conversion levels), but a much higher water-gas shift activity, with C5+ Sel% being drastically reduced to 31-35%, generally due to the loss of carbon in CO reacting towards CO2 as an unwanted side product. Methane selectivities were increased here, too

[0149] Even better results were obtained when the Fischer-Tropsch process was operated using high-temperature carbided catalyst as in Table 1 , but at lower temperature and higher H2:CO ratio. Table 3 provides CO conversion and product selectivity data for the catalyst of composition: molar Si / Fe ratio = 0.046, molar K / Fe ratio = 0.012 and molar Cu / Fe ratio = 0.028. Reaction conditions were H2 / CO = 1.8 (15% inert), 200 °C, p~30 bar, GHSV -2000-3000. Reported hydrocarbon product selectivities are amongst all products (including CO2).Table 3

[0150] At these CO conversion conditions in the 20-30% range, consistently high C5+ selectivities >70% were obtained (Table 3), ranging up to 77% C5+ Sel%.

[0151] Table 4 provides data for a similar process as described with respect to Table 3, but with a higher reaction temperature. Reaction conditions were H2 / CO = 1.8 (15% inert), 220 °C, p~30 bar, GHSV -6600. Reported hydrocarbon product selectivities are amongst all products (including CO2).Table 4

[0152] Raising the temperature provided C5+ selectivities in the range of 65-69% at reasonably high CO conversion levels of 31-43%.

[0153] Additional runs were performed with various catalysts and various Fischer- Tropsch reaction conditions, all using catalysts carbided under the high-temperature conditions provided above. FIG. 5 provides a summary of the results, including a summary of the power of each variable to influence the results. The results demonstrate that despite the different catalyst synthesis methods and the range of catalyst promoter levels, the most dominant factor influencing the C5+ Selectivity (calculated amongst all products includingCO2) is the reaction temperature. Combined with the effect of GHSV (higher GHSV were more favorable in terms of improved C5+ Sel%), these two parameters achieve an R2fit of 0.79, compared to only a slight improvement to 0.81 by taking further catalyst properties into account.Example 4 - CO2 Selectivity Depends on Carbiding Conditions

[0154] The present inventors note that the conversion of CO in an iron-based Fischer- Tropsch system can be complicated by the water-gas shift reaction. For example, while the rate of the Fischer-Tropsch reaction can be increased by the presence of copper, so to can the rate of the water-gas shift, which can undesirably convert CO to CO2. The present inventors have noted surprisingly that the method of activation of the catalyst has a strong effect on the selectivity for CO2. A variety of catalyst materials were prepared via either of the processes described in Examples 1 and 2 above. Three different catalyst materials were prepared, containing similar amounts of iron, silicon, and potassium, as well as differing amounts of copper (i.e., 0 wt%, 1 wt%, and 5 wt%). The three catalyst materials were initially provided in as-calcined form (i.e., in oxidic form) and then carbided using either a high-temperature carbiding procedure or a low-temperature carbiding procedure, providing six unique carbided catalyst materials for Fischer-Tropsch synthesis. The six carbided Fischer-Tropsch catalyst materials were then subjected to Fischer-Tropsch reaction conditions with varying reaction temperature, H2:CO, and inerts content. Table 5 summarizes the wt% of iron, silicon, copper, and potassium in these catalyst materials a metal basis and the carbiding procedure used to activate those materials.

[0155] The high-temperature carbiding procedure was as follows: After an initial drying step using inert gas, a H2reduction near atmospheric conditions was performed at 400 °C for 16 hours to substantially reduce all iron oxides to metallic Fe. Following the reduction, carbiding was performed for 4-6 hours at 400 °C with 3% CO (balance H2). After the carbiding step, the catalyst was cooled to a temperature below 150 °C. Then, the gas composition was switched to syngas and the stream pressurized to reaction pressure (30 bar), held for 1 hour, and then ramped to reaction temperature at 2 °C / min.

[0156] The low-temperature carbiding procedure is as follows: After an initial drying step using inert gas, a H2reduction near atmospheric conditions was performed at 400 °C for 16 hours to substantially reduce all iron oxides to metallic Fe. Following the reduction, carbiding was performed at 180 °C with 35% CO (balance H2). After the carbiding step, the catalyst was cooled to a temperature below 150 °C. Then, the gas composition was switched to syngas and the stream pressurized to reaction pressure (30 bar), held for 1 hour, and then ramped to reaction temperature at 2 °C / min.

[0157] As described in more detail below, high-temperature carbiding conditions provide carbide that is substantially in the form of x-Fe5C2, while low-temperature carbiding conditions provide carbide that is substantially in the e-Fe3C and r|-Fe2C.Table 5

[0158] The catalyst materials were carbided, then subjected to Fischer-Tropsch reaction conditions in a 16-fold parallel fixed bed reactor unit, wherein two blocks of 8 tubes, each having an inner diameter of 2.4 mm, are independently heated, and gas feed flows are equally split and distributed. The unit has hot knockout pots at 150 °C for collecting high boiling waxes and cold knockout pots at 10 °C to collect water and light organics. Around 250 mg of catalyst materials 1-3 were each diluted with 500 mg SiC and placed in separate reactor tubes of the 16-fold parallel fixed bed reactor unit. The catalyst materials were carbided according to either the high temperature carbiding (i.e. , 400 °C, 3% CO) or low temperature carbiding (i.e., 180 °C, 35% CO) methods as described above. The catalysts prepared in this fashion generally had a BET area of 194-213 m2 / g and a pore volume of ~0.3 cc / g. These catalysts were subjected to Fischer-Tropsch reaction conditions as follows: 245 °C, 30 bar, H2:CO 1.8:1 , 51% inert gas, GHSV -2500-3000. The results of these reactions are summarized in Table 6. The reported hydrocarbon selectivities (i.e., CH4, C2-C4, C5+ hydrocarbons) do not include CO2, and the reported C2-Cs oxygenates selectivities do not include CO2and CH4.Table 6

[0159] For these Fischer-Tropsch reactions, catalyst materials activated via the low temperature carbiding method exhibited roughly comparable CO conversions to the catalysts activated via the high temperature carbiding method. However, catalyst materials activated via low-temperature carbiding exhibited substantially higher selectivity for CO2 and CH4, both generally undesirable products in a Fischer-Tropsch products. Low temperature carbiding also greatly increases the selectivity for C2-C8 oxygenate products, increasing the selectivity for C2-C8 oxygenates by two- to three-fold. The carbiding conditions also affects the effect copper content has in the Fischer-Tropsch reaction. For processes using high temperature carbiding methods, increasing copper content in the catalyst material leads to higher CO conversion, while increasing copper content in catalysts activated via low temperature carbiding led to lower CO conversion. The addition of copper generally reduces the C5+ selectivity for all of the Fischer-Tropsch catalysts described in this Example. However, the person of ordinary skill in the art can determine if the addition of copper to the catalyst material can lead to an improvement in C5+ productivity overall, despite the slight decrease in selectivity for C5+ hydrocarbons.

[0160] Table 7 provides CO conversion and product selectivity data for the same 6 combinations of catalyst material and carbiding method of Table 5. In Table 7, the catalysts were subjected to Fischer-Tropsch reaction conditions as follows: 230 °C, 30 bar, H2CO 1.8:1 , 51% inert gas, GHSV -2500-3000.

[0161] Table 7.

[0162] The reactions in Table 2 were run at a lower temperature than those in Table 1 (i.e. , 230 °C compared to 245 °C). Lower reaction temperatures generally lead to lower CO conversions for all reactions compared to the Fischer-Tropsch reactions run at 245 °C.However, lower temperatures also improve the selectivity for C5+ hydrocarbons by lowering the selectivities for CO2, CH4, and C2-C4 products. Similarly to the reactions run in Table 1 , the addition of copper increases the CO conversion when activated with high temperature carbiding and decreases the CO conversion when activated with low temperature carbiding.

[0163] Table 8 provides CO conversion and product selectivity data for the same 6 combinations of catalyst material and carbiding method of Table 5. In Table 8, the catalysts were subjected to Fischer-Tropsch reaction conditions as follows: 245 °C, 30 bar, H2CO 1.0:1 , 40% inert gas, GHSV -2500.Table 8.

[0164] The reactions in Table 8 were run using syngas with a lower ratio of H2:CO (i.e., 1.0:1 H2:CO compared to 1.8:1 H2:CO). The lower H2:CO conditions highlight the benefits of incorporating copper into the catalyst material, as the presence of copper greatly improves CO conversion for catalyst materials activated using high temperature carbiding (improving CO conversion from 39% to 75%). The lower H2:CO conditions generally led to increased C5+ selectivity in all cases.

[0165] Table 9 provides CO conversion and product selectivity data for the same 6 combinations of catalyst material and carbiding method of Table 5. In Table 9, the catalysts were subjected to Fischer-Tropsch reaction conditions as follows: 245 °C, 30 bar, H2CO 1.8:1 , 16% inert gas, GHSV -2500-3000.

[0166] Table 9.

[0167] The reactions in Table 9 were run with a lower content of inert gas (16% inert gas compared to 51% inert gas). The same general trends can be observed for this set of reactions. The inclusion of copper in the catalyst material generally lowers Cs+ selectivity. Under high temperature carbiding conditions, the addition of copper increases CO conversion and selectivity for CO2, CH4, and C2-C8 oxygenates. Under lower temperature carbiding conditions, the addition of copper decreases CO conversion, and low temperature carbiding generally leads to much higher selectivity for C2-C8 oxygenates. The experiments described in Example 4 demonstrates the relationship between carbiding conditions and copper content, and the person of ordinary skill in the art can determine which combination is best suited for a particular Fischer-Tropsch process.Example 6 - XRD analysis of Fischer-Tropsch Catalyst Material

[0168] This example demonstrates the preparation and characterization of an unsupported iron-oxide catalyst material (pre-catalyst) with the chemical composition (on an oxide basis) 50Fe2O3 / 4.4SiC>2 / 2.6CuO / 0.5K2O. A typical procedure is as follows:1) Weigh 484.8 (1.20 mol) of Fe(NO3)3'9H2O and 7.26 g (0.0312 mol) of CU(NO3)2'2.5H2O was first dissolved in 1200 g of deionized water under vigorous stirring to obtain solution A.2) Weigh 457.8 g (2.75 mol) of K2CO3 and dissolved in 1200 g of deionized water in a separate container under vigorous stirring to obtain solution B.3) Weigh 1200 g of DI water into a 5-liter 5-neck round bottom flask equipped with a mechanical stirrer, a heating mantle / temperature control system and a condenser.4) Increase the temperature of the water in the round bottom flask to 80 °C, then adjust the pH of the water to 9 with the K2CO3 solution prepared above.5) Simultaneously add the solutions A and B at the same rate while monitoring the pH of the precipitation medium; adjust by changing the addition rate of solution B.6) Rinse all the containers with 400 g of DI water and combine the solution into to round bottom flask.7) To the above slurry add 11.00 (0.0528 mol) tetraethyl orthosilicate under vigorous stirring.8) After allowing the resultant solid to age at 80 °C for 2h, turn off the heater and let the system to cool down to a temperature below 40 °C.9) Transfer the slurry into six 1000 mL centrifuge bottles; adjust the quantify in each bottle to 1000 g with DI water.10) Separate the solids using a centrifuge at 9000 rpm for 10 min.11) Re-slurry the solids in 4 L DI water and repeat the separation and washing for 4 more times.12) Recover the solid in the final round through vacuum filtration, then dry the solid in a hood overnight followed by drying in an oven at 110 °C overnight.13) Pulverize the solid using a mortar grinder, then load the powder into a Rotavapor flask loaded with 0.83 g of K2CO3 dissolved into 150 g of DI water.14) Let the slurry to rotate at 60 °C for 60 min.15) Remove the water at 60 °C under 125 mm Hg vacuum.16) Recover the solid and dry in an oven at 110 °C overnight, then calcine the solid in air flow at 300 °C for 4h, via a ramp of 2 °C / min to obtain the oxidic catalyst material.

[0169] Properties of the oxidic catalyst material were measured using nitrogen adsorption-desorption method at 77.15 K; the sample was degassed under 10-6mm Hg vacuum at 300 °C overnight. The results are as follows:

[0170] BET area: 203 m2 / g

[0171] Pore volume: 0.24 cm3 / g

[0172] FIG. 6 provides the XRD pattern of this sample, in which a-Fe20s was the only crystalline phase discerned, which is indicated by the vertical lines. Other chemical compositions in this sample are highly dispersed or present in amorphous form that were not discernable by XRD.Example 7 - Activating catalyst material to form x-FesCa

[0173] This example demonstrates the conversion of a Fischer-Tropsch catalyst material, which has a composition of 50.00Fe203 / 3.91Si02 / 2.58CuO / 3.85K20 into a carbided form. In this experiment, a small amount (about 70 mg) of the sample was loaded into a high-pressure Mdssbauer in-situ cell equipped with high-pressure beryllium windows. Transmission57Fe Mdssbauer spectra were collected at 120 or 4.2 K with a sinusoidal velocity spectrometer using a57Co(Rh) source. Velocity calibration was performed using an a-Fe foil at room temperature. The source and the absorbing samples were maintained at the same temperature during the measurements. The high-pressure beryllium windows used in the cell in this study contained -0.08% Fe impurity, the spectral contribution of which was fitted and removed from the final spectra.

[0174] In the first step of the experiment, the catalyst material is dried under N2flow at 300 °C. The dried catalyst material was then reduced using 5% H2in N2at 400 °C (near atmospheric pressure) for 4h, via a heating ramp of 0.5 °C / min. The reduced sample was then converted into x-Fe5C2 by carbiding using 20% CO in H2at 350 °C near atmospheric pressure. FIG. 7 depicts the in-situ Mdssbauer spectra of the sample collected at 4 different time points at 120 K: from top to bottom, after drying, after reduction, and after carbiding for 2 hours and 4 hours. In the Mdssbauer spectra, there is one major trace from each of the samples, as well as additional traces attributed to each of the iron species that are present in different coordination environments. The Mdssbauer spectrum taken after reduction of the catalyst material shows a larger trace that indicates the spectrum of the sample overlaid with standard spectrum of a-Fe. Close to the baseline, there is a separate trace indicating the difference between the actual measured trace and the standard spectrum of a-Fe; this difference trace is consistent with the presence of a minor amount of ferrihydrite-like species. The Mdssbauer spectra taken during the carbiding of the catalyst material exhibit a tallest envelope trace indicating the spectrum of the sample, whereas the other traces indicate the spectrum in different coordination environments in the x-FesC2 structure. Each Mdssbauer spectrum was analyzed using Mosswinn 4.0, and the resulting spectroscopic parameters and phase quantification of the iron species are summarized in Table 10.

[0175] Table 10.

[0176] Based on the above results, all of the iron in the catalyst material is in its oxidic form (i.e., Fe3+or a-Fe2Os) after drying. After reduction, 97% of the iron in the catalyst material is converted into a-Fe (i.e., Fe°). The in situ Mdssbauer spectrum shows that all of the iron, including unreduced Fe3+, is further converted into phase pure x-FesC2 during the carburization process.Example 8 - Activating catalyst material to form c-FesC and q-FeaC

[0177] The same catalyst material prepared for the high temperature carbiding process in Example 7 is used in a low temperature carbiding process to prepare a catalyst wherein the iron is primarily in its e-FesC and r|-Fe2C forms. In this experiment, a small amount (about 70 mg) of the sample was loaded into a high-pressure Mdssbauer in-situ cell equipped with high-pressure beryllium windows. Transmission57Fe Mdssbauer spectra were collected according to the Mdssbauer parameters described in Example 7. In the first step of the experiment, the catalyst material is dried under N2 flow at 300 °C. The dried catalyst material was then reduced using 5% H2 in N2 at 400 °C near atmospheric pressure for 4h, via a heating ramp of 0.5 °C / min. The reduced sample was then converted into E-Fe3C and q-Fe2C by carbiding using 33% CO in H2at 180 °C near atmospheric pressure. FIG. 8 depicts the in-situ Mdssbauer spectra of the sample collected at 4 different time points at 120 K: after reduction and after carbiding for 2 hours, 4 hours, and 24 In the Mdssbauer spectra, there is one major trace from each of the samples, as well as additional traces attributed to each of the iron species that are present in different coordination environments. The Mdssbauer spectrum taken after reduction of the catalyst material (i.e., FIG. 9A) shows a larger trace that indicates the spectrum of the sample overlaid with standard spectrum of a-Fe. Close to the baseline, there is a separate trace indicating the difference between the actual measured trace and the standard spectrum of a-Fe; this difference trace is consistent with the presence of a minor amount of ferrihydrite-like species. The Mdssbauer spectrum taken after carbiding the catalyst material for 24 hours (i.e., FIG. 9D) shows a trace of the largest envelope indicating the spectrum of the sample, along with two relatively large sub-traces indicating spectra of £-Fe2C and q-Fe2C, as well as a minor trace along the baseline indicating the difference of the profile fitting, the difference trace consistent with the spectrum of a-Fe. Each Mdssbauer spectrum was analyzed using Mosswinn 4.0, and the resulting spectroscopic parameters and phase quantification of the iron species are summarized in Table 11.Table 11.

[0178] Similar to the experiment described in Example 7, 97% of the iron in the catalyst material is reduced to Fe° after drying and reducing the catalyst material. After 2 hours of the low temperature carbiding process, around 45% of the iron is converted into iron carbide, leaving 55% of the iron still as metallic iron. This is in contrast to the high temperature carbiding process, wherein all of the iron is carbided at the end of 2 hours. The iron carbide content gradually increases with low temperature carbiding, wherein 97% of the iron is carbided in the form of £-Fe3C and r|-Fe2C at the end of 24 hours. The ratio of r|-Fe2C: £- Fe3C increases over time as well, shedding insight on the metastability of these iron carbide polymorphs. Examples 7 and 8 highlight the ability to selectively form different iron carbide species via different carbiding procedures.

[0179] Additional aspects of the disclosure are provided by the following enumerated embodiments, which may be combined in any number and in any combination that is not logically or technically inconsistent.Embodiment 1. A Fischer-Tropsch catalyst material comprising at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of potassium to iron in the range of 0.003-0.10.Embodiment 2. The Fischer-Tropsch catalyst material according to embodiment 1 , wherein the Fischer-Tropsch catalyst material comprises at least 80 wt% iron, e.g., at least 85 wt% iron, on an elemental basis exclusive of carbon.Embodiment 3. The Fischer-Tropsch catalyst material according to embodiment 1 , wherein the Fischer-Tropsch catalyst material comprises at least 90 wt% iron on an elemental basis, e.g., at least 92 wt% iron, on an elemental basis exclusive of carbon .Embodiment 4. The Fischer-Tropsch catalyst material according to any of embodiments 1-3, wherein the molar ratio of silicon to iron is in the range of 0.01-0.10, e.g., 0.01-0.08, or 0.01-0.06.Embodiment 5. The Fischer-Tropsch catalyst material according to any of embodiments 1-3, wherein the molar ratio of silicon to iron is in the range of 0.02-0.12, e.g., 0.02-0.10, or 0.02-0.08, or 0.02-0.06.Embodiment 6. The Fischer-Tropsch catalyst material according to any of embodiments 1-3, wherein the molar ratio of silicon to iron is in the range of 0.03-0.12, e.g., 0.03-0.10, or 0.03-0.08, or 0.03-0.06.Embodiment 7. The Fischer-Tropsch catalyst material according to any of embodiments 1-6, wherein the molar ratio of potassium to iron is in the range of 0.003-0.08, e.g., 0.003-0.06, or 0.003-0.04.Embodiment 8. The Fischer-Tropsch catalyst material according to any of embodiments 1-6, wherein the molar ratio of potassium to iron is in the range of 0.006-0.10, e.g., 0.006-0.08, or 0.006-0.06, or 0.006-0.04.Embodiment 9. The Fischer-Tropsch catalyst material according to any of embodiments 1-6, wherein the molar ratio of potassium to iron is in the range of 0.009-0.10, e.g., 0.009-0.08, or 0.009-0.06, or 0.009-0.04.Embodiment 10. The Fischer-Tropsch catalyst material according to any of embodiments 1-9, further comprising copper, in a molar ratio of copper to iron in the range up to 0.12.Embodiment 11. The Fischer-Tropsch catalyst material according to embodiment 10, wherein the molar ratio of copper to iron is up to 0.10, e.g., up to 0.08, or up to 0.06.Embodiment 12. The Fischer-Tropsch catalyst material according to embodiment 10, wherein the molar ratio of copper to iron is in the range of 0.005 0.12, e.g., in the range of 0.005-0.10, or 0.005-0.08, or 0.005-0.06.Embodiment 13. The Fischer-Tropsch catalyst material according to embodiment 10, wherein the molar ratio of copper to iron is in the range of 0.01-0.12, e.g., in the range of 0.01-0.10, or 0.01-0.08, or 0.01-0.06.Embodiment 14. The Fischer-Tropsch catalyst material according to embodiment 10, wherein the molar ratio of copper to iron is in the range of 0.02-0.12, e.g., in the range of 0.02-0.10, or 0.02-0.08, or 0.02-0.06.Embodiment 15. The Fischer-Tropsch catalyst material according to any of embodiments 1-9, wherein the Fischer-Tropsch catalyst material is essentially free of copper (e.g., the molar ratio of copper to iron is no more than 0.01 , or no more than 0.005, or no more than 0.001).Embodiment 16. The Fischer-Tropsch catalyst material according to any of embodiments 1-15, wherein a molar ratio of the sum of silicon, copper (if present) and potassium to iron is in the range of 0.04-0.18, e.g., 0.4-0.14, or 0.4-0.10, or 0.05-0.18, or 0.5- 0.14, or 0.5-0.10, or 0.06-0.18, or 0.06-0.14, or 0.06-0.10.Embodiment 17. The Fischer-Tropsch catalyst material according to any of embodiments 1-16, further comprising manganese, in a molar ratio of manganese to iron in the range up to 0.05, e.g., up to 0.04, or up to 0.03.Embodiment 18. The Fischer-Tropsch catalyst material according to any of embodiments 1-16, further comprising manganese, in a molar ratio of manganese to iron in the range of 0.005-0.05, e.g., 0.005-0.04, or 0.005-0.03, or 0.01-0.05, or 0.01-0.04, or 0.01- 0.03..Embodiment 19. The Fischer-Tropsch catalyst material according to any of embodiments 1-18, wherein a molar ratio of lithium to iron is no more than 0.003, e.g., no more than 0.002, or no more than 0.001.Embodiment 20. The Fischer-Tropsch catalyst material according to any of embodiments 1-19, wherein a molar ratio of silver to iron is no more than 100 ppm, e.g., no more than 25 ppm, or no more than 10 ppm, or no more than 5 ppm, or no more than 3 ppm.Embodiment 21. The Fischer-Tropsch catalyst material according to any of embodiments 1-20, in substantially oxidic form.Embodiment 22. The Fischer-Tropsch catalyst material according to embodiment 21, wherein at least 50 atom% of the iron is in the form of ferrihydrite.Embodiment 23. The Fischer-Tropsch catalyst material according to any of embodiments 1-22, wherein at least 90 wt% of the Fischer-Tropsch catalyst material is made up of iron, silicon, potassium, and, if present, copper and / or manganese, e.g., at least 95 wt%, or at least 98 wt%, or at least 99 wt%, or at least 99.5 wt%, or at least 99.8 wt%, on an elemental basis exclusive of carbon.Embodiment 24. A process for making a Fischer-Tropsch catalyst material according to any of claims 1-23, the process comprising: providing a first liquid comprising one or more iron-containing compounds dissolved in a first solvent; contacting the first liquid with precipitating ions in the presence of potassium ions to provide a potassium-containing precipitate and a supernatant; isolating the potassium-containing precipitate from the supernatant; optionally, washing the isolated precipitate with a washing liquid to reduce concentration of alkali metal thereof; and calcining the isolated precipitate to provide the Fischer-Tropsch catalyst material.Embodiment 25. The process of embodiment 24, wherein the iron-containing compounds are selected from water-soluble metal salts (e.g., nitrates and acetates).Embodiment 26. The process of embodiment 24 or embodiment 25, wherein each of the one or more first solvents is an aqueous fluid, e.g., water.Embodiment 27. The process of any of embodiments 24-26, wherein each of the one or more first liquids has a pH of no greater than 7.Embodiment 28. The process of any of embodiments 24-27, wherein the precipitating ions comprise carbonate ions and / or hydroxide ions.Embodiment 29. The process of any of embodiments 24-28, wherein the precipitating ions are provided as an potassium base, e.g., a potassium carbonate or a potassium hydroxide.Embodiment 30. The process of any of embodiments 24-28, wherein the precipitating ions are provided as a non-metal containing base, e.g., ammonium carbonate or ammonium hydroxide.Embodiment 31. The process of embodiment 30, wherein the potassium ions are provided by a potassium salt.Embodiment 32. The process of any of embodiments 24-31 , wherein the contacting of the one or more first liquids with the precipitating ions is performed at a precipitation pH that is alkaline, for example, in the range of 8-12, e.g., in the range of 8-11, or 8-10, or 8.5-12, or 8.5-11, or 8.5-10, or 9-12, or 9-11, or 9-10..Embodiment 33. The process of any of embodiment 32, wherein the process further comprises maintaining the pH of the contacting step at an alkaline pH, for example, in the range of 8-12, e.g., in the range of 8-11, or 8-10, or 8.5-12, or 8.5-11 , or 8.5-10, or 9-12, or 9-11, or 9-10.Embodiment 34. The process of embodiment 33, wherein the pH of the contacting step is maintained by controlling a rate of addition of precipitating ions.Embodiment 35. The process of any of embodiments 24-34, wherein the contacting step is conducted at an elevated temperature (e.g., in the range of 60-100 °C, or 60-90 °C, or 60-80 °C, or 70-100 °C, or 70-90 °C, or 70-80 °C.).Embodiment 36. The process of any of embodiments 24-35, further comprising treating the precipitate with a silicon source such as tetraethylorthosilicate.Embodiment 37. The process of any of embodiments 24-36, wherein the process further comprising aging the alkali-containing precipitate in contact with the supernatant (e.g., before isolation).Embodiment 38. The process of any of embodiments 24-37, wherein the washing the isolated precipitate with an aqueous washing liquid to reduce a concentration of potassium thereof is performed.Embodiment 39. The process of embodiment 38, wherein washing the precipitate is repeated until a desired level of potassium is provided to the Fischer-Tropsch catalyst material.Embodiment 40. The process of any of embodiments 24-39, wherein the process further comprises drying the isolated precipitate before the calcining.Embodiment 41. The process of any of embodiments 24-40, wherein the calcining is conducted for a time in the range of 0.5 to 24 hours (e.g., in the range of 0.5 to 15 hours, or 0.5 to 10 hours, or 0.5 to 5 hours).Embodiment 42. The process of any of embodiments 24-41 , wherein calcining is conducted at a temperature is in the range of 100-600 °C, e.g., in the range of 200-600 °C, or 300-600 °C, or 100-500 °C, or 200-500 °C, or 300-500 °C.Embodiment 43. A process for making a Fischer-Tropsch catalyst material according to any of claims 1-23, the process comprising: providing a first liquid comprising one or more iron-containing compounds dissolved in a first solvent; contacting the one or more first liquids with precipitating ions in the substantial absence of alkali metal ions to provide a substantially alkali-free precipitate and a supernatant;isolating the substantially alkali-free precipitate from the supernatant; adding potassium metal ions to the substantially alkali-free precipitate in order to provide a potassium-containing precipitate; and calcining the isolated precipitate to provide the Fischer-Tropsch catalyst material.Embodiment 44. The process of embodiment 43, wherein the iron-containing compounds are selected from water-soluble metal salts (e.g., nitrates and acetates).Embodiment 45. The process of embodiment 43 or embodiment 44, wherein each of the one or more first solvents is an aqueous fluid, e.g., water.Embodiment 46. The process of any of embodiments 43-45, wherein each of the one or more first liquids has a pH of no greater than 7.Embodiment 47. The process of any of embodiments 43-46, wherein the precipitating ions comprise carbonate ions and / or hydroxide ions.Embodiment 48. The process of any of embodiments 43-47, wherein the precipitating ions are provided as a non-metal containing base, e.g., ammonium carbonate or ammonium hydroxide.Embodiment 49. The process of any of embodiments 43-48, wherein the contacting of the one or more first liquids with the precipitating ions is performed at a precipitation pH that is alkaline, e.g., in the range of 8-12, e.g., in the range of 8-11, or 8-10, or 8.5-12, or 8.5-11 , or 8.5-10, or 9-12, or 9-11, or 9-10.Embodiment 50. The process of any of embodiment 49, wherein the process further comprises maintaining the pH of the contacting step at an alkaline pH, for example, in the range of 8-12, e.g., in the range of 8-11 , or 8-10, or 8.5-12, or 8.5-11 , or 8.5-10, or 9-12, or 9-11, or 9-10.Embodiment 51. The process of embodiment 50, wherein the pH of the contacting step is maintained by controlling a rate of addition of precipitating ions.Embodiment 52. The process of any of embodiments 43-51 , wherein the contacting step is conducted at an elevated temperature (e.g., in the range of 60-100 °C, or 60-90 °C, or 60-80 °C, or 70-100 °C, or 70-90 °C, or 70-80 °C.).Embodiment 53. The process of any of embodiments 43-52, wherein the process further comprising aging the substantially alkali-free precipitate in contact with the supernatant (e.g., before isolation).Embodiment 54. The process of any of embodiments 43-53, further comprising treating the precipitate with a silicon source such as tetraethylorthosilicate.Embodiment 55. The process of any of embodiments 43-54, further comprising washing the isolated precipitate with a washing liquid.Embodiment 56. The process of any of embodiments 43-55, wherein the process further comprises drying the isolated precipitate before the calcining.Embodiment 57. The process of any of embodiments 43-56, wherein the calcining is conducted for a time in the range of 0.5 to 24 hours (e.g., in the range of 0.5 to 15 hours, or 0.5 to 10 hours, or 0.5 to 5 hours).Embodiment 58. The process of any of embodiments 43-57, wherein calcining is conducted at a temperature is in the range of 100-600 °C, e.g., in the range of 200-600 °C, or 300-600 °C, or 100-500 °C, or 200-500 °C, or 300-500 °C.Embodiment 59. The process of any of embodiments 43-57, wherein adding potassium ions to the substantially alkali-free precipitate in order to provide a potassium-containing precipitate is performed before calcining the precipitate.Embodiment 60. A carbided Fischer-Tropsch catalyst material, that is the Fischer- Tropsch catalyst material of any of embodiments 1-23, or a Fischer-Tropsch catalyst material made by a process of any of claims 24-59, in carbided form.Embodiment 61. A carbided Fischer-Tropsch catalyst material of Embodiment 60, wherein at least 50 atom% of the iron is in a carbide form.Embodiment 62. A carbided Fischer-Tropsch catalyst material comprising: at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10,wherein at least 50 atom% of the iron of the carbided Fischer-Tropsch catalyst material is in the form of iron carbide.Embodiment 63. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-62, wherein at least 60 atom% of the iron is in a carbide form, e.g., at least 70 atom%, or at least 80 atom%, or at least 90 atom%.Embodiment 64. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-62, wherein in the range of 50-99 atom% of the iron is in a carbide form, e.g., in the range of 50-95%, or 50-90%, or 50-85%.Embodiment 65. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-62, wherein in the range of 60-99 atom% of the iron is in a carbide form, e.g., in the range of 60-95%, or 60-90%, or 60-85%.Embodiment 66. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-62, wherein in the range of 70-99 atom% of the iron is in a carbide form, e.g., in the range of 70-95%, or 70-90%.Embodiment 67. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-62, wherein in the range of 80-99 atom% of the iron is in a carbide form, e.g., in the range of 80-95%, or 80-90%.Embodiment 68. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-62, wherein in the range of 90-99 atom% of the iron is in a carbide form, e.g., in the range of 90-98%, or 90-95%.Embodiment 69. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein no more than 20 atom% of iron is in oxidic form, e.g., no more than 10 atom%.Embodiment 70. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein no more than 5 atom% of iron is in oxidic form, e.g., no more than 2 atom%.Embodiment 71. The carbided Fischer-Tropsch catalyst material of Embodiment 69 or Embodiment 70, used in a Fischer-Tropsch synthesis having a feed CO2 / CO ratio no more than 0.5, e.g., no more than 0.2Embodiment 72. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein at least 5 atom% of the iron is in an oxide phase, e.g., at least 10 atom%, or at least 15 atom%, or at least 20 atom%.Embodiment 73. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein in the range of 5-50 atom% of the iron is in an oxide phase, e.g., 5-45 atom%, or 5-40 atom%.Embodiment 74. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein in the range of 10-50 atom% of the iron is in an oxide phase, e.g., 10-45 atom%, or 10-40 atom%.Embodiment 75. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein in the range of 15-50 atom% of the iron is in an oxide phase, e.g., 15-45 atom%, or 15-40 atom%.Embodiment 76. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-68, wherein in the range of 20-50 atom% of the iron is in an oxide phase, e.g., 20-45 atom%, or 20-40 atom%.Embodiment 77. The carbided Fischer-Tropsch catalyst material of any of embodiments 72-76, used in a Fischer-Tropsch synthesis having a feed CO2 / CO ratio in excess of 0.5, e.g., in excess of 1.Embodiment 78. The carbided Fischer-Tropsch catalyst material of any of embodiments 60-77, wherein the amount of iron is as described in any of Embodiments 2-3.Embodiment 79. The carbided Fischer-Tropsch catalyst material of any of embodiments 60-78, wherein the molar ratio of silica to iron is as described in any of Embodiments 4-6.Embodiment 80. The carbided Fischer-Tropsch catalyst material of any of embodiments 60-79, wherein the molar ratio of potassium to iron is as described in any of Embodiments 7-9.Embodiment 81. The carbided Fischer-Tropsch catalyst material of any of embodiments 60-80, wherein an amount of copper is as described in any of Embodiments 10-15.Embodiment 82. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-81 , wherein the molar ratio of the sum of silicon, copper and potassium to iron is as described in Embodiment 16.Embodiment 83. The carbided Fischer-Tropsch catalyst material of any of embodiments 60-82, wherein an amount of manganese is as described in Embodiment 17 or Embodiment 18.Embodiment 84. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-83, wherein a molar ratio of lithium to iron is as described in Embodiment19.Embodiment 85. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-84, wherein a molar ratio of silver to iron is as described in Embodiment20.Embodiment 86. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-85, wherein the carbided Fischer-Tropsch catalyst material is an unsupported catalyst material.Embodiment 87. The carbided Fischer-Tropsch catalyst material of any of Embodiments 60-86, wherein at least 90 wt% of the catalyst material is made up of iron, silica, carbon and potassium, and, if present, manganese, e.g., at least 95 wt%, or at least 98 wt%, or at least 99 wt%, or at least 99.5 wt%, or at least 99.8 wt%, on an elemental basis exclusive of carbon.Embodiment 88. The carbided Fischer-Tropsch catalyst material of any of embodiments 60-87, comprising x-FesC2.Embodiment 89. The carbided Fischer-Tropsch catalyst material of embodiment 88, wherein at least 50 atom% of the carbided iron of the carbided Fischer-Tropsch catalyst material is in the form of x-Fe5C2, e.g., at least 60 atom%, or at least 70 atom%.Embodiment 90. The carbided Fischer-Tropsch catalyst material of embodiment 88, wherein at least 75 atom% of the carbided iron of the carbided Fischer-Tropsch catalyst material is in the form of x-Fe5C2, e.g., at least 80 atom%.Embodiment 91. The carbided Fischer-Tropsch catalyst material of embodiment 88, wherein at least 85 atom% of the carbided iron of the carbided Fischer-Tropsch catalyst material is in the form of x-Fe5C2, e.g., at least 90 atom%.Embodiment 92. A process for providing a carbided Fischer-Tropsch catalyst material of any of Embodiments 60-91, the process comprising carbiding a Fischer-Tropsch catalyst material of any of embodiments 1-23 or a Fischer-Tropsch catalyst material made by a process of any of claims 24-59 to provide the carbided Fischer-Tropsch catalyst material.Embodiment 93. The process of Embodiment 92, wherein carbiding the Fischer- Tropsch catalyst material to provide the carbided Fischer-Tropsch catalyst material comprises optionally, treating the Fischer-Tropsch catalyst material with a reducing gas stream comprising hydrogen for a time and at a temperature sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in metallic form; then treating the Fischer-Tropsch catalyst material with a carbiding gas stream comprising carbon monoxide and / or carbon dioxide (e.g., carbon monoxide), at a temperature of at least 180 °C for a time sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in carbided form, e.g., for at least 5 hours.Embodiment 94. The process of embodiment 93, wherein the treatment of the Fischer- Tropsch catalyst material with the reducing gas stream is not performed.Embodiment 95. The process of embodiment 93, wherein the treatment of the Fischer- Tropsch catalyst with the reducing gas stream is performed.Embodiment 96. The process of embodiment 95, wherein the treating of the Fischer- Tropsch catalyst material with the reducing gas stream comprising hydrogen is performed in the substantial absence of carbon monoxide.Embodiment 97. The process of embodiment 95 or embodiment 96, wherein the reducing gas stream further comprises an inert gas (e.g., nitrogen).Embodiment 98. The process of embodiment 97, wherein the hydrogen and inert gas are present in the reducing gas stream in a ratio of at least 1 :1.Embodiment 99. The process of any of embodiments 93-98, wherein treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a temperature in the range of 250-650 °C (e.g., in the range of 250-600 °C, or 250-550 °C, or 250-500 °C).Embodiment 100. The process of any of embodiments 93-98, wherein treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a temperature in the range of 300-650 °C (e.g., in the range of 300-600 °C, or 300-550 °C, or 300-500 °C).Embodiment 101. The process of any of embodiments 93-98, wherein treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a temperature in the range of 350-650 °C (e.g., in the range of 350-600 °C, or 350-550 °C, or 350-500 °C).Embodiment 102. The process of any of embodiments 93-101, wherein treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted at a pressure within 10 bar of atmospheric pressure, e.g., within 7 bar of atmospheric pressure, or within 5 bar of atmospheric pressure.Embodiment 103. The process of any of embodiments 93-102, wherein treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted for a time of at least 12 hours, e.g., at least 14 hours.Embodiment 104. The process of any of embodiments 93-102, wherein treating the Fischer-Tropsch catalyst material with the reducing gas stream is conducted for a time in the range of 12 to 30 hours (e.g., 12 to 24 hours, or 14 to 30 hours, or 14 to 24 hours).Embodiment 105. The process of any of embodiments 93-105, wherein the treatment with the reducing gas stream is performed to provide a Fischer-Tropsch catalyst material in which at least 60 atom% of the iron is in reduced form, e.g., at least 70 atom%.Embodiment 106. The process of any of embodiments 93-105, wherein the treatment with the reducing gas stream is performed to provide a Fischer-Tropsch catalyst material in which at least 80 atom% of the iron is in reduced form, e.g., at least 85 atom%.Embodiment 108. The process of any of embodiments 93-106, wherein the carbiding gas stream comprises carbon monoxide.Embodiment 108. The process of any of embodiments 93-107 (particularly 92 and 107 as it depends from embodiment 92), wherein the carbiding gas stream further comprises hydrogen.Embodiment 109. The process of embodiment 108, wherein the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide) of at least 1:1 (e.g., at least 2:1, or at least 5:1, or at least 10:1 , or at least 15:1, or at least 20:1 , or at least 25:1 , or at least 30:1).Embodiment 110. The process of embodiment 108, wherein the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide) of 1:1 to 100:1 , e.g., in the range of 2:1 to 100:1, or 5:1 to 100:1, or 10:1 to 100:1 , or 15:1 to 100:1, or 20:1 to 100:1 , or 25:1 to 100:1 , or 30:1 to 100:1.Embodiment 111. The process of embodiment 108, wherein the carbiding gas stream comprises hydrogen and carbon monoxide and / or carbon dioxide in a molar ratio of hydrogen to carbon monoxide and carbon dioxide (e.g., hydrogen to carbon monoxide) of 1:1 to 50:1, e.g., in the range of 2:1 to 50:1, or 5:1 to 50:1 , or 10:1 to 50:1, or 15:1 to 50:1 , or 20:1 to 50:1 , or 25:1 to 50:1, or 30:1 to 50:1.Embodiment 112. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature of at least 200 °C, e.g., at least 220 °C.Embodiment 113. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 180-450 °C (e.g., in the range of 180-400 °C, or 180-350°C, or 180-300 °C).Embodiment 114. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 200-450 °C (e.g., in the range of 200-400 °C, or 200-350°C, or 200-300 °C).Embodiment 115. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 220-450 °C (e.g., in the range of 220-400 °C, or 220-350 °C, or 220-300 °C).Embodiment 116. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature of at least 300 °C, e.g., at least 325 °C, or at least 350 °C, or at least 375 °C, or at least 400 °C.Embodiment 117. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 300-650 °C, e.g., 300-600 °C, or 300-550 °C or 300-500 °C.Embodiment 118. The process of any of embodiments 93-111, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 310-650 °C, e.g., 310-600 °C, or 310-550 °C or 310-500 °C.Embodiment 119. The process of any of embodiments 93-111 , wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 325-650 °C, e.g., 325-600 °C, or 325-550 °C, or 325-500 °CEmbodiment 120. The process of any of embodiments 93-111 , wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 350-650 °C, e.g., 350-600 °C, or 350-550 °C or 350-500 °C.Embodiment 121. The process of any of embodiments 93-111 , wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 375-650 °C, e.g., 375-600 °C, or 375-550 °C, or 375-500 °C.Embodiment 122. The process of any of embodiments 93-111 , wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a temperature in the range of 400-650 °C, e.g., 400-600 °C, or 400-550 °C, or 400-500 °CEmbodiment 123. The process of any of embodiments 93-122, wherein treating the Fischer-Tropsch catalyst material with the carbiding gas stream is conducted at a pressure within 10 bar of atmospheric pressure, e.g., within 7 bar of atmospheric pressure, or within 5 bar of atmospheric pressure.Embodiment 124. The process of any of embodiments 93-123, wherein treating the Fischer-Tropsch catalyst material with a carbiding gas stream is conducted for a time in the range of 3-20 hours, e.g., 5-20 hours, or 3-15 hours, or 5-15 hours.Embodiment 125. A process for performing a Fischer-Tropsch synthesis, the process comprising providing a carbided Fischer-Tropsch catalyst material of any of embodiments 60-91 , or a carbided Fischer-Tropsch catalyst material made by the process of any of embodiments 92-124); contacting at a reaction temperature and pressure the carbided Fischer-Tropsch catalyst material with a feed stream comprising H2 and CO to provide a product stream comprising C5+ hydrocarbons.Embodiment 126. The process of embodiment 125, wherein the feed stream has a H2:CO ratio in the range of 0.5: 1 to 6: 1.Embodiment 127. The process of embodiment 125 or embodiment 126, wherein the feed stream has a H2:CO ratio in the range of 1 :1 to 3:1, e.g., 1:1 to 2.5:1.Embodiment 128. The process of embodiment 125 or embodiment 126, wherein the feed stream has a H2:CO ratio of at least 1.4:1, e.g., in the range of 1.4:1 to 3:1 , or 1.4:1 to 2.5:1.Embodiment 128. The process of any of embodiments 125-128, wherein the feed stream includes up to 80% of one or more inerts, e.g., up to 70 mol%, up to 60 mol%, or up to 50mol%, or 15-70 mol%, or 30-70 mol%, or 15-60 mol%, or 30-60 mol%, or 15-50 mol%, or 30- 50 mol%.Embodiment 130. The process of any of embodiments 125-128, wherein the feed stream includes up to 80% of one or more inerts selected from methane and nitrogen, e.g., up to 70 mol%, up to 60 mol%, or up to 50 mol%, or 15-70 mol%, or 30-70 mol%, or 15-60 mol%, or 30-60 mol%, or 15-50 mol%, or 30-50 mol%.Embodiment 131. The process of any of embodiments 125-130, wherein the feed stream includes up to 80% of CO2, e.g., up to 70 mol%, up to 60 mol%, or up to 50 mol%, or 15-70 mol%, or 30-70 mol%, or 15-60 mol%, or 30-60 mol%, or 15-50 mol%, or 30-50 mol%.Embodiment 132. The process of embodiment 131, wherein the molar ratio of CO2 to CO in the feed stream is at least 0.5:1, e.g., at least 0.7:1 or at least 1 :1.Embodiment 133. The process of any of embodiments 125-132, wherein the feed stream has a water content of no more than 10 mol%, e.g., or no more than 2 mol%, or no more than 0.5 mol%.Embodiment 134. The process of any of embodiments 125-133, wherein the reaction temperature is in the range of 150-400 °C (e.g., in the range of 150-350 °C, or 150-300 °C, or 150-250°C, or 150-200°C, or 200-400 °C, or 200-350 °C, or 200-300°C, or 200-250 °C, or 250-400 °C, or 250-350 °C, or 250-300 °C, or 300-400 °C).Embodiment 135. The process of any of embodiments 125-133, wherein the reaction temperature is in the range of 200-350 °C.Embodiment 136. The process of any of embodiments 125-133, wherein the reaction temperature is in the range of 180-250 °C, e.g., in the range of 190-250 °C, or 200-250 °C, or 210-250 °C, or 220-250 °C.Embodiment 137. The process of any of embodiments 125-136, wherein the pressure is in the range of 10-50 barg (e.g., 20-50 barg, or 25-50 barg, or 10-40 barg, or 20-40 barg, or 25-40 barg or 10-35 barg, or 20-35 barg, or 25-35 barg).Embodiment 138. The process of any of embodiments 125-136, wherein the pressure is in the range of 20-50 barg.Embodiment 139. The process of any of embodiments 125-138, wherein the Fischer- Tropsch reaction is conducted at a GHSV in the range of 1 ,000 to 2,000,000 IT1(e.g., in the range of 1 ,000 to 1 ,200,000 IT1, or 1 ,000 to 500,000 IT1, or 1 ,000 to 100,000 IT1, or 5,000 to 1 ,200,000 IT1, or 5,000 to 500,000 IT1, or 5,000 to 100,000 IT1, or 10,000 to 1 ,200,000 IT1, or 10,000 to 500,000 IT1, or 10,000 to 100,000 IT1).Embodiment 140. The process of any of embodiments 125-139, wherein the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C5+ selectivity of at least 30%, e.g., at least 40%, or at least 50%.Embodiment 141. The process of any of embodiments 125-139, wherein the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C5+ selectivity of at least 60%, e.g., at least 60%, or at least 80%.Embodiment 142. The process of any of embodiments 125-141 , wherein the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C2-4 selectivity of no more than 30%, e.g., no more than 25%, or no more than 20%.Embodiment 143. The process of any of embodiments 125-142, wherein the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a methane selectivity of no more than 20%, e.g., no more than 15%, or no more than 10%, or no more than 5%.Embodiment 144. The process of any of embodiments 125-143, wherein the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C2-8 oxygenate selectivity of no more than 30%, e.g., no more than 25%, or no more than 20%.Embodiment 145. The process of any of embodiments 125-144, wherein the contacting of the Fischer-Tropsch catalyst with the feed stream to provide the product stream is performed with a C2-8 oxygenate selectivity of no more than 15%, e.g., no more than 10%, or no more than 5%.Embodiment 146. The process of any of embodiments 125-145, further comprising separating at least a portion of C1-C4 hydrocarbons from the product stream to provide a light hydrocarbon stream.Embodiment 147. The process of embodiment 146, further comprising burning at least a portion of the light hydrocarbon stream to provide energy, e.g., heat energy or electrical energy.Embodiment 148. The process of embodiment 147, wherein the heat energy is used to heat the feed stream.Embodiment 149. The process of any of embodiments 125-148, further comprising recycling at least a portion of H2 of the product stream to the feed stream.Embodiment 150. The process of any of embodiments 125-149, further comprising recycling at least a portion of CO of the product stream to the feed stream.Embodiment 151. The process of any of embodiments 125-150, further comprising recycling at least a portion of inerts of the product stream to the feed stream.Embodiment 152. The process of any of embodiments 125-151 , wherein one or more products are provided from at least a portion of C5+ hydrocarbons of the product stream.Embodiment 153. The process of embodiment 152, wherein the one or more products include fuels (e.g., gasoline, diesel fuel, aviation fuel), lubricants and waxes.Embodiment 154. The process of any of embodiments 125-153, further comprising hydroprocessing at least a portion of C5+ hydrocarbons of the product stream.Embodiment 155. The process of any of embodiments 125-154, wherein at least part of the H2 of the feed stream is from a renewable source.Embodiment 156. The process of any of embodiment 125-155, wherein at least a portion of the hydrogen of the feed stream is green hydrogen.Embodiment 157. The process of any of embodiment 125-155, wherein at least a portion of the hydrogen of the feed stream is blue hydrogen.Embodiment 158. The process of any of embodiment 125-155, wherein at least a portion of the hydrogen of the first feed stream or the second feed stream is grey hydrogen, black hydrogen, brown hydrogen, pink hydrogen, turquoise hydrogen, yellow hydrogen, and / or white hydrogen.Embodiment 159. The process of any of embodiments 125-158, further comprising providing at least a portion of H2 to the first feed stream and / or the second feed stream by electrolysis of water.Embodiment 160. The process of embodiment 159, wherein the electrolysis of water is performed using at least partially electricity from a renewable source.Embodiment 161. The process of embodiment 159 or embodiment 160, wherein the electrolysis of water is performed using at least partially electricity generated from steam made by heat exchange from the first product stream and / or the second product stream, or by burning a light hydrocarbon stream (e.g., methane from biogas).Embodiment 162. The process of any of embodiments 125-161 , wherein the catalyst material is provided in a fixed bed.Embodiment 163. The process of any of embodiments 125-161, wherein the catalyst material is provided in a fluidized bed, i.e. , in which the catalyst material is fluidized by the feed stream.

[0180] The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings and / or examples making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Thus, before the disclosed processes and devices are described, it is to be understood that the aspects described herein are not limited to specific embodiments, apparatuses, or configurations, and as such can, of course, vary. It is also to be understood that the terminology usedherein is for the purpose of describing particular aspects only and, unless specifically defined herein, is not intended to be limiting.

[0181] The terms “a,” “an,” “the” and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0182] All processes described herein can be performed in any suitable order of steps unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0183] Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application.

[0184] As will be understood by one of ordinary skill in the art, each embodiment disclosed herein can comprise, consist essentially of or consist of its particular stated element, step, ingredient or component. As used herein, the transition term “comprise” or “comprises” means includes, but is not limited to, and allows for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts. The transitional phrase “consisting of’ excludes any element, step, ingredient or component not specified. The transition phrase “consisting essentially of” limits the scope of the embodiment to the specified elements, steps, ingredients or components and to those that do not materially affect the embodiment.

[0185] Unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0186] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0187] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0188] Some embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0189] Furthermore, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the present invention may be utilized in accordance with the teachings herein. Accordingly, the present invention is not limited to that precisely as shown and described.

Claims

We claim:Claim 1. A process for performing a Fischer-Tropsch synthesis, the process comprising providing a carbided Fischer-Tropsch catalyst material comprising: at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of potassium to iron in the range of 0.003-0.10; and contacting at a reaction temperature in the range of 180-250 °C and a reaction pressure the carbided Fischer-Tropsch catalyst material with a feed stream comprising H2and CO to provide a product stream comprising C5+ hydrocarbons, wherein the carbided Fischer-Tropsch catalyst material is provided in a fixed bed or in a fluidized bed in which the carbided Fischer-Tropsch catalyst material is fluidized by the feed stream.Claim 2. The process of Claim 1 , wherein the carbided Fischer-Tropsch catalyst material is provided by a process comprising: providing a Fischer-Tropsch catalyst material comprising: at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of potassium to iron in the range of 0.003-0.10; optionally, treating the Fischer-Tropsch catalyst material with a reducing gas stream comprising hydrogen for a time and at a temperature sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in metallic form; then treating the Fischer-Tropsch catalyst material with a carbiding gas stream comprising carbon monoxide in a molar ratio of hydrogen to carbon monoxide in the range of 2:1 to 100:1 , at a temperature of at least 300 °C for a time sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in carbided form.Claim 3. The process of Claim 2, wherein the treatment of the Fischer-Tropsch catalyst with the reducing gas stream is performed, and wherein treating of the Fischer-Tropsch catalyst material with the reducing gas stream comprising hydrogen is performed in the substantial absence of carbon monoxide.Claim 4. The process of any of Claims 1-3, wherein the carbided Fischer-Tropsch catalyst material further comprises copper, in a molar ratio of copper to iron of up to 0.12.Claim 5. The process of any of Claims 1-3, wherein the carbided Fischer-Tropsch catalyst material has a molar ratio of copper to iron of no more than 0.005.Claim 6. The process of any of Claims 1-5, wherein the carbided Fischer-Tropsch catalyst material has a molar ratio of the sum of silicon, copper (if present) and potassium to iron in the range of 0.04-0.18.Claim 7. The process of any of Claims 1-6, wherein the carbided Fischer-Tropsch catalyst material further comprises manganese, in a molar ratio of manganese to iron in the range of 0.005-0.05.Claim 8. The process of any of Claims 1-6, wherein the carbided Fischer-Tropsch catalyst material has a molar ratio of lithium to of is no more than 0.003 and a molar ratio of silver to iron of no more than 100 ppm.Claim 9. The Fischer-Tropsch catalyst material according to any of Claims 1-8, wherein at least 95 wt% of the Fischer-Tropsch catalyst material, on an elemental basis excluding carbon, is made up of iron, silicon, potassium, and, if present, copper and / or manganese.Claim 10. A process for providing carbided Fischer-Tropsch catalyst material, the carbided Fischer-Tropsch catalyst material comprising: at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of alkali metal to iron in the range of 0.003-0.10, wherein at least 50 atom% of the iron of the carbided Fischer-Tropsch catalyst material is in the form of iron carbide, the process comprising. providing a Fischer-Tropsch catalyst material comprising: at least 75 wt% iron, on an elemental basis exclusive of carbon; silicon, in a molar ratio of silicon to iron in the range of 0.01-0.12; and potassium, in a molar ratio of potassium to iron in the range of 0.003-0.10;optionally, treating the Fischer-Tropsch catalyst material with a reducing gas stream comprising hydrogen for a time and at a temperature sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in metallic form; then treating the Fischer-Tropsch catalyst material with a carbiding gas stream comprising carbon monoxide in a molar ratio of hydrogen to carbon monoxide in the range of 2:1 to 100:1 , at a temperature of at least 300 °C for a time sufficient to provide at least 50 atom% of the iron of the Fischer-Tropsch catalyst material in carbided form.Claim 11. The process of Claim 10, wherein the treatment of the Fischer-T ropsch catalyst with the reducing gas stream is performed, and wherein treating of the Fischer- Tropsch catalyst material with the reducing gas stream comprising hydrogen is performed in the substantial absence of carbon monoxide.Claim 12. The process of Claim 10 or Claim 11 , wherein in the carbided Fischer- Tropsch catalyst material no more than 20 atom% of iron is in oxidic form.Claim 13. The process of any of Claims 10-12, wherein in the carbided Fischer-Tropsch catalyst material at least 60 atom% of the carbided iron is in the form of x-FesC2.Claim 14. The process of any of Claims 10-13, wherein at least 50 atom% of the iron of the Fischer-Tropsch catalyst material is in the form of ferrihydrite.Claim 15. A carbided Fischer-Tropsch catalyst material made by the process of any of Claim 10-14.

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