Integrated fischer-tropsch processes

Abstract

The present disclosure relates generally to a process for preparing hydrocarbons. The process comprises providing an iron Fischer-Tropsch (FT) feed stream comprising carbon dioxide and hydrogen; contacting the iron FT feed stream with an iron-based FT catalyst under conditions sufficient to form C1-C4 hydrocarbons comprising C2-C4 olefins and C5+ hydrocarbons comprising C5+ olefins; contacting at least a portion of the C2-C4 olefins and the C5+ olefins with an olefin oligomerization catalyst to provide oligomerized hydrocarbons, and wherein the process forms an FT-oligomerization product stream; in a separation zone, separating the FT-oligomerization product stream to provide a light product stream rich in hydrogen, carbon monoxide, carbon dioxide, and C1-C4 hydrocarbons, and a heavy product stream rich in water and C5+ hydrocarbons; and including at least a portion of the C2-C4 olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream in the iron FT feed stream.

Description

INTEGRATED FISCHER-TROPSCH PROCESSESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 616,382, filed December 29, 2023 and European Patent Application No. 24166571.0, filed March 26, 2024, each of which are incorporated by reference herein in their entirety.BACKGROUND OF THE DISCLOSURE1 Field

[0002] The present disclosure relates generally to iron-based Fischer-Tropsch catalysts and processes for performing Fischer-Tropsch reactions. The present disclosure also relates to integrating processes for performing Fischer-Tropsch reactions and processes for performing olefin oligomerization reactions.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] FT 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 FT 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 FT 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. However, in contrast to cobalt, iron-based catalysts generally exhibit high water gas shift (WGS) activity. The water gas shift reaction competes with the Fischer-Tropsch process by converting CO and H2O to CO2and hydrogen, as shown below:CO2conversion on the iron-based FT catalyst can convert CO2to CO for conversion through to hydrocarbons, but this is limited by the WGS equilibrium i.e., in-situ formed CO and H2O can react back to a certain extent to CO2and H2, limiting the CO2conversion to a low level. Accordingly, higher water gas shift activity can lead to high CO2yields and lower selectivity of the conversion of feedstock carbon to C5+ hydrocarbons, which are the generally-desired FT products. As such, the main challenge in iron-based FT process are to obtain good CO2 conversion towards C5+ hydrocarbons while minimizing the undesirable effects of the high water-gas shift activity of iron-based catalysts. Furthermore, the hydrocarbons produced by iron-based FT processes are generally olefins, and further processing is necessary to provide the desired long chain hydrocarbons to make fuels, base oils, and lubricants. As such, there is a need to provide improved iron-based FT processes.SUMMARY

[0006] In one aspect, the present disclosure provides for a process for preparing hydrocarbons, the process comprising providing an iron Fischer-Tropsch (FT) feed stream comprising carbon dioxide and hydrogen, the iron FT feed stream comprising no more than 10 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%; contacting the iron FT feed stream with an iron-based FT catalyst under conditions sufficient to form C1-C4 hydrocarbons comprising C2-C4 olefins and C5+ hydrocarbons comprising C5+ olefins; contacting at least a portion of the C2-C4olefins and the C5+ olefins formed by the contacting of the iron FT feed stream with an olefin oligomerization catalyst to provide oligomerized hydrocarbons; wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst forms an FT-oligomerization product stream; in a separation zone, separating the FT-oligomerization product stream to provide a light product stream rich in hydrogen, carbon monoxide, carbon dioxide, and Ci- 04 hydrocarbons (including C2-C4 olefins); and a heavy product stream rich in water and C5+ hydrocarbons; and including at least a portion of the C2-C4 olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream in the iron FT feed stream.

[0007] In another aspect, the disclosure provides for a process wherein oxygenated hydrocarbons are formed during the contacting the iron FT feed stream with an iron-based FT catalyst.

[0008] In another aspect, the disclosure provides for a process further comprising, after contacting the iron FT feed stream with an iron-based FT catalyst and prior to contacting at least a portion of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalysts: contacting at least a portion of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst to provide additional C2-C4olefins and C5+ olefins.

[0009] In another aspect, the disclosure provides for a process wherein: at least a portion of the additional C2-C4olefins and C5+ olefins provided by contacting of the oxygenated hydrocarbons with the dehydration and / or hydrodeoxygenation catalyst is contacted with the olefin oligomerization catalyst to provide oligomerized hydrocarbons; and the FT-oligomerization product stream includes the contacting of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst.BRIEF DESCRIPTION OF FIGURES

[0010] The accompanying drawings are included to provide a further understanding of the methods 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.

[0011] FIG. 1 is a schematic diagram of a process for performing an integrated Fischer- Tropsch process as described herein.

[0012] FIG. 2 is a schematic diagram of a process for performing an integrated Fischer- Tropsch process as described herein.

[0013] FIG. 3 is a schematic diagram of a process for performing an integrated Fischer- Tropsch process as described herein.

[0014] FIG. 4 is a schematic diagram of a process for performing an integrated Fischer- Tropsch process as described herein.

[0015] FIG. 5 is a schematic diagram of a cooling loop as described herein.

[0016] FIG. 6 is a schematic diagram of a process for performing an integrated Fischer- Tropsch process as described herein.DETAILED DESCRIPTION

[0017] The present disclosure is concerned with iron-based FT processes for converting CO2to hydrocarbons. One of the challenges associated with using CO2in the feed stream of FT processes is to activate the CO2at reasonable temperatures to form CO for conversion into hydrocarbons. Here, the present inventors note that there is further H2O produced during the Fischer-Tropsch reaction, shown below:CO + 2 H2-> [-CH2-] + H2OThe present inventors have noted that this water formed by the Fischer-Tropsch reaction can be especially problematic, in that it can push the water-gas shift equilibrium toward formation of CO2from CO, which is undesirable from the standpoint of conversion to desirable products. Additionally, due to the elevated temperatures required to achieve good CO2conversion to CO, the subsequent reaction of CO to hydrocarbons will produce light hydrocarbons that are highly olefinic, rather than the desired C5+ hydrocarbons

[0018] Here, the present inventors have found that integrated Fischer-Tropsch processes with an olefin oligomerization reaction can be used to convert light olefins (e.g., C2-C4olefins) to heavy hydrocarbons (e.g., C5+ hydrocarbons) as C2-C4olefins can themselves be oligomerized to provide desired C5+ hydrocarbons, which consequently increases the overall conversion of CO2in the FT processes. Additionally, any unreacted light hydrocarbons (e.g., C2-C4olefins), hydrogen, carbon monoxide, and carbon dioxide can be recycled back to the Fischer-Tropsch process for subsequent processing.

[0019] Accordingly, in one aspect, the present disclosure provides a process for preparing hydrocarbons. The process comprises providing an iron FT feed stream comprising carbon dioxide and hydrogen, the iron FT feed stream comprising no more than 10 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%; contacting the iron FT feed stream with an iron-based FT catalyst under conditions sufficient to form Ci-C4hydrocarbons comprising C2-C4olefins and C5+ hydrocarbons comprising C5+ olefins; contacting at least a portion of the C2-C4olefins and the C5+ olefins formed by the contacting of the iron FT feed stream with an olefin oligomerization catalyst to provide oligomerized hydrocarbons, and wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst forms an FT-oligomerization product stream; in a separation zone, separating the FT-oligomerization product stream to provide a light product stream rich in hydrogen, carbon monoxide, carbon dioxide, and Ci-C4hydrocarbons (including C2-C4olefins); and a heavy product stream rich in water and C5+ hydrocarbons; and including at least a portion of the C2-C4olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream in the iron FT feed stream.

[0020] An example of such a process is shown schematically in FIG. 1 . In the embodiment of FIG. 1 , the process 100 includes providing an iron FT feed stream 11 1 comprising carbon dioxide and hydrogen , the iron FT feed stream comprising no more than 10 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%; to a reactor 105 and contacting the iron FT feed stream 11 1 with an iron-based FT catalyst 1213 under conditions sufficient to form C1-C4 hydrocarbons comprising C2-C4 olefins and C5+ hydrocarbons comprising C5+ olefins; contacting at least a portion of the C2-C4 olefins and the C5+ olefins formed by the contacting of the iron FT feed stream 11 1 with an olefin oligomerization catalyst 123 to provide oligomerized hydrocarbons, and wherein the contacting of the iron FT feed stream 11 1 with the iron-based FT 113 catalyst and the contacting of the C2-C4 olefins and the C5+ olefins with the olefin oligomerization catalyst forms an FT-oligomerization product stream 122; in a separation zone 150, separating the FT-oligomerization product stream to provide a light product stream 136 rich in hydrogen, carbon monoxide, carbon dioxide, and C1-C4 hydrocarbons (including C2-C4 olefins); and a heavy product stream 152 rich in water and C5+ hydrocarbons; and including at least a portion of the C2-C4 olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream 136 in the iron FT feed stream.

[0021] As used herein, a “feed stream” is used to mean the total material input to a process step, e.g., an FT process, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single inlet or multiple inlets. For example, CO2and H2of the iron FT feed stream can be provided to the iron-based FT catalyst in a single physical stream (e.g., in a single pipe to reactor 110), or in multiple physical streams (e.g., separate inlets for CO2and H2, or one inlet for fresh CO2and H2and another for recycled CO2 and / or H2). Similarly, a “product stream” is used to mean the total material output from a process step, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single outlet or multiple outlets.

[0022] The iron FT feed stream as described herein contains both CO2and H2(e.g., provided to a reaction zone in a single physical stream or multiple physical streams In various embodiments as otherwise described herein, the molar ratio of H2to CO2(i.e., H2 / CO2) in the feed stream as described herein is at least 0.1 , e.g., at least 0.5. In some embodiments, the molar ratio of H2to CO2in the feed stream as described herein is at least 0.9, e.g., at least 1 , at least 1 .5, or at least 2. In some embodiments, the molar ratio of H2toCO2in the feed steam as described herein is no more than 20, e.g., no more than 15, or no more than 10. In some embodiments, the molar ratio of H2to CO2in the feed steam as described herein is no more than 6, no more than 5, or no more than 4. For example, in some embodiments, the molar ratio of H2to CO2in the feed stream as described herein is in the range of 1-10, e.g., 2-10 or 2-5. In some embodiments as described herein, the molar ratio of H2to CO2in the feed stream is in the range of 1 to 4 (e.g., 1 .25 to 4, or 1 .5 to 4, or 1 to 3.5, or 1 .25 to 3.5, or 1 .5 to 3.5, or 1 to 3, or 1 .25 to 3, or 1 .5 to 3). The person of ordinary skill in the art will provide a desired ratio of H2to CO2in the iron FT feed stream, based on the disclosure herein, that provides a desirable conversion of selectivity. Excess H2can, if consistent with a desirable conversion and selectively, be provided to flow through the system to increase the conversion of CO2.

[0023] Other gases may also be included in the iron FT feed stream. For example, in some embodiments, the iron FT feed stream comprises CO. The CO may be provided to the reaction zone in a single physical stream or multiple physical streams. In some embodiments, the CO is from a product stream of the process as described herein, e.g., the FT-oligomerization product stream as described below. As discussed above, iron-based FT catalysts are known to be highly active for the WGS / rWGS reaction. The present inventors hypothesize that including CO in the feed stream(s) can provide a compromise between the rWGS reaction and the FT reaction to provide the desired hydrocarbons.

[0024] Accordingly, in various embodiments as otherwise described herein, the molar ratio of H2to oxides of carbon (e.g., CO2and / or CO) is in the range of 1 :1 to 6:1 , e.g., in the range of 1 .5:1 to 3:1 . The person of ordinary skill in the art will provide a desired ratio of H2to oxides of carbon in the iron FT feed stream, based on the disclosure herein, that provides a desirable conversion of selectivity. Excess H2can, if consistent with a desirable conversion and selectively, be provided to flow through the system to increase the conversion of CO2.

[0025] Water may also be included in the iron FT feed stream. For example, the water may be from a product stream of the process as described herein, e.g., the FT- oligomerization product stream as described below. In various embodiments as otherwise described herein, the iron FT feed stream comprises no more than 10 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%. In various embodiments, the iron FT feed stream comprising no more than 8 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%.

[0026] In some cases, it can be desirable to include inert gases (i.e., components that are not H2or CO2) to the iron FT feed stream. For example, in some embodiments, the ironFT streams further comprises nitrogen and / or methane. For example, it can be desirable to perform the FT process in the presence of a significant amount of inerts (i.e., components that are not H2or CO or CO2). For example, in various embodiments, the iron FT 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 iron FT feed stream includes up to 70 mol%, or up to 60 mol%, 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 iron FT feed stream includes up to 80% of one or more inerts selected from CO2, 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%. In various embodiments, the iron FT 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%. The person of ordinary skill in the art will appreciate that inerts can be provided from a variety of sources. Moreover, as described in more detail below, inerts can be recycled to the iron FT feed stream from a product stream of the processes as described herein.

[0027] As noted above, the process as described herein includes contacting the iron FT feed stream comprising carbon dioxide and hydrogen with an iron-based FT catalyst to perform an FT reaction. The FT catalysts as described herein are not particularly limited, and the person of ordinary skill in the art would be able to choose a catalyst as appropriate for the FT processes.

[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 the art will appreciate, ICP can detect most elements, but is blind to hydrogen, nitrogen and oxygen. Accordingly, amounts quantified “on an elemental basis” are determined by ICP with respect to amounts of ICP-measurable elements, i.e., excluding hydrogen, oxygen, and nitrogen. Moreover, it can be convenient to quantify as-carbided catalysts without considering carbon in the quantification. Accordingly, amounts quantified “on an elemental basis exclusive of carbon” are determined by ICP excluding hydrogen, oxygen, nitrogen, and carbon.

[0029] The FT catalysts of the present disclosure (e.g., whether or not in a carbided form) include iron. The amount of iron is measured by ICP. For purposes of the present disclosure, the amount of iron present is calculated on an elemental basis, i.e., as a weightpercentage of iron atoms based on the total weight of ICP-measurable elements in the catalyst material, regardless of the form in which that iron may be present. 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 (such as a mixed metal oxide with any other metal components, or single metal oxides like Fe2O3, FeO, and Fe3O4), a metal carbide, a metal halide, or a combination thereof. For example, in various embodiments, the FT catalysts comprise at least 15 wt% iron, at least 20 wt% iron, or at least 25 wt% iron, on an elemental basis exclusive of carbon. In various embodiments, the FT catalysts comprise at least 30 wt% iron, at least 35 wt% iron, or at least 40 wt% iron, on an elemental basis exclusive of carbon.

[0030] In various embodiments as otherwise described herein, the FT catalyst is an alkali-promoted iron FT catalyst. The present inventors note that alkali can provide increased water-gas shift activity, which is because the ratio of carbon dioxide to carbon monoxide is maintained at a high value, water-gas shift activity in the FT reactor can further convert CO2to CO and through to desirable products. In various embodiments as described herein, the FT catalyst comprises in the range of 0.2-5 wt% alkali metal, on an elemental basis exclusive of carbon. For example, in various embodiments, the FT catalyst comprises in the range of 0.2-3 wt%, or 0.2-2 wt%, or 0.3-5 wt%, or 0.3-3 wt%, or 0.3-2 wt%, or 0.4-5 wt%, or 0.4-3 wt%, or 0.4-2 wt% alkali metal, on an elemental basis exclusive of carbon. In some embodiments as described herein, the FT catalyst comprises in the range of 0.5-5 wt% alkali metal, e.g., 0.5-3 wt%, or 0.5-2 wt%, or 0.7-5 wt%, or 0.7-3 wt%, or 0.7-2 wt%, on an elemental basis exclusive of carbon. In various embodiments, the FT catalyst material comprises in the range of 1-5 wt% alkali metal, on an elemental basis. For example, in various embodiments, the FT catalyst comprises 1-3 wt%, or 1-2 wt%, or 1 .3-5 wt%, or 1 .3-3 wt%, or 1.3-2 wt% alkali metal, on an elemental basis exclusive of carbon. In some embodiments described herein, the FT catalyst comprises 1.5-5 wt% alkali metal, on an elemental basis exclusive of carbon. For example, in some embodiments the FT catalyst comprises 1 .5-3 wt%, or 1 .5-2.5 wt%, or 1 .5-5 wt%, or 1 .5-3 wt%, or 1 .5-2.5 wt% alkali metal, on an elemental basis exclusive of carbon.

[0031] In some embodiments, the alkali metal present in the FT catalyst is one or more of sodium, potassium, rubidium, and cesium. In some embodiments as described herein, the alkali metal is one or more of sodium and potassium. For example, in some embodiments as described herein, the alkali metal is sodium. In particularly desirable embodiments, the alkali metal is potassium.

[0032] The person of ordinary skill in the art will appreciate that the iron-based FT catalysts 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 supports of the iron-based FT catalysts can be provided themselves as discrete bodies of material, e.g., as porous particles, pellets or shaped extrudates, with the metals provided thereon to provide the iron FT catalyst material. However, in other embodiments, an iron FT catalyst material of the disclosure can itself be formed as a layer on an underlying substrate. The underlying substrate is not particularly limited. It can be formed of, e.g., a metal or metal oxide, and can itself be provided in a number of forms, such as particles, pellets, shaped extrudates, or monoliths. The person of ordinary skill in the art will select an appropriate iron-based FT catalysts for the particular reactor system.

[0033] Conventionally, iron-containing catalyst materials are prepared for use as active catalyst materials 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 catalyst material to metallic iron. Then, when exposed to Fischer-Tropsch reaction conditions, a substantial part of this iron is converted to carbide. It is thus not conventionally necessary to provide a separate carbiding treatment; rather, the carbiding is a natural result of reaction conditions. Accordingly, in various embodiments, the iron-based FT catalysts is activated by contact with H2and oxides of carbon (e.g., CO and CO2).

[0034] However, a dedicated activation step may be conducted in any convenient manner. For example, in various embodiments, the activation includes a reduction step, in which the 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 material 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 FT catalyst material as described herein react to metallic iron (Fe°).

[0035] 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 isnitrogen. 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.

[0036] In various embodiments, treating the iron-based FT catalyst with the reducing gas stream is conducted at a temperature in the range of 200-650 °C. For example, in various embodiments as described herein, treating the iron-based FT catalyst with the reducing gas stream is conducted at a temperature in the range of 200-600 °C, or 200-550 °C, or 200-500 °C. In various embodiments as described herein, treating the iron FT catalyst material with the 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 iron FT catalyst material with the reducing gas stream is conducted at a temperature in the range of 400-650 °C, or 400-600 °C, or 400-550 °C, or 400-500 °C.

[0037] As described above, treating the catalyst material with the reducing gas stream is conducted for a time sufficient to provide at least 50 atom% of the iron of the catalyst material in metallic form. In various embodiments, treating the 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 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.

[0038] The person of ordinary skill in the art will be able to determine appropriate reducing conditions to provide a catalyst material with at least 50 atom% iron in reduced form. In various embodiments, the treatment with the reducing gas stream is performed to provide a 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 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.

[0039] The activation can include treating the catalyst material with a carbiding gas stream comprising 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 catalyst material in carbided form. This can be performed, e.g., after a treatment with a reducing gas as described above.

[0040] 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 50 atom% of the iron is in a carbide form, e.g., at least 55 atom%, or at least 60 atom%. In various embodiments of the carbided Fischer- Tropsch catalyst materials of the disclosure, in the range of 50-95 atom% of the iron is in acarbide form, e.g., in the range of 50-90%, or 50-85%, or 50-80%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 55-95 atom% of the iron is in a carbide form, e.g., in the range of 55-90%, or 55-85%, or 55-80%. In various embodiments of the carbided Fischer-Tropsch catalyst materials of the disclosure, in the range of 60-95 atom% of the iron is in a carbide form, e.g., in the range of 60-90%, or 60-85%, or 60-80%. 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.

[0041] The present inventors note that, while oxidic iron is not a highly active catalyst for Fischer-Tropsch synthesis, it can catalyze water-gas shift reactions. In cases where the feed to the FT synthesis includes a high proportion of CO2, the present inventors have determined that water-gas shift activity can be highly desirable to convert that CO2to CO for use in the Fischer-Tropsch synthesis. Accordingly, the present inventors have determined that some oxidic iron in the carbided Fischer-Tropsch catalyst material can be beneficial. Accordingly, 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%. However, the present inventors also note that oxidic iron forms are generally not active catalysts for Fischer-Tropsch synthesis. Accordingly, in various embodiments, it can be desirable to limit the amount of oxidic iron in the carbided Fischer-Tropsch catalyst material. In various embodiments of the carbided Fischer-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%. 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 carbiding conditions to provide a desired degree of oxidic iron in the carbided Fischer-Tropsch catalyst materials of the disclosure.

[0042] In various embodiments, at least 30 atom% of the oxidic iron of the carbided Fischer-Tropsch catalyst material is in the form of Fe3O4. The present inventors note that this partially-reduced oxide has especially good activity as a reverse water-gas shift catalyst.In various embodiments, at least 40 atom% of the oxidic iron of the carbided Fischer- Tropsch catalyst material is in the form of Fe3O4, e.g., at least 50 atom%. In various embodiments, at least 60 atom% of the oxidic iron of the carbided Fischer-Tropsch catalyst material is in the form of Fe3O4, e.g., at least 70 atom%. The person of ordinary skill in the art can select carbiding conditions, particularly with respect to conditions under which the material is reduced, to provide a desired amount of Fe3O4. The amount of oxidic iron present as of Fe3O4is determined using Mbssbauer spectroscopy.

[0043] In various embodiments of the present disclosure as otherwise described herein, the reducing gas / carbiding gas comprises at least a portion of H2and CO (if present) from feed stream(s). For example, in some embodiments, the process further comprises separating at least a portion of H2and at least a portion of CO of the feed stream(s) and contacting it with the iron-based Fischer-Tropsch catalyst material to activate the iron-based Fischer-Tropsch catalyst material. In the process 200 shown schematically in FIG. 2, at least a portion of H2and COstream 225 is separated from the iron FT feed stream 211 and contacted with the iron FT catalyst material 213 to activate it. In alternative embodiments as otherwise described herein, the process includes separating at least a portion of H2and CO (desirably in a ratio of at least 1 :1 or at least 3:1) from the iron FT product stream and contacting it with the iron-based FT catalyst to activate the iron-based FT catalyst. For example, in the process of FIG. 2, stream 214 including CO2and stream 215 including H2can be recycled from the iron FT product stream to reactor 210 to activate the iron-based FT catalysts 213. This separation need not be continuous; rather, it need only be performed for a time desirable to provide reducing gas to the iron-based FT catalyst for activation. Of course, as would be understood by the person of skill in the art, other sources of H2or CO may be used to provide reducing gas to the iron-based FT catalyst for activation. However, separate carbiding processes are not necessary, as the iron FT catalyst material can be carbided under the iron FT reaction conditions, especially when treated first with a reducing gas as described above.

[0044] Notably, the present inventors have determined that the iron-based FT catalyst as described herein can provide desirably high C5+ selectivity. The Fischer-Tropsch process is typically used to make Cs+ hydrocarbons, for example, unsubstituted Cs+ hydrocarbons (e.g., alkanes and alkenes) and / or oxygenated C5+ hydrocarbons. As used herein, the term “oxygenated hydrocarbons” is used to refer to hydrocarbons substituted with one or more oxygen atoms (e.g., alcohols, aldehydes, ketones, carboxylic acids). For example, in various embodiments as described herein, the FT reaction has a C5+ selectivity (i.e., for all C5+ species) of at least 45%, e.g., at least 50%, or at least 55%. For example, in some embodiments, the selectivity for C5+ alkanes is at least 40%, e.g., at least 50%, or at least60%. In some embodiments, the contacting of the iron-based FT catalyst with the feed 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 iron-based FT catalyst with the feed 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, the contacting of the iron-based FT catalyst with the feed stream is performed with an oxygenated hydrocarbon selectivity (e.g., C2.8oxygenate selectivity) of no more than 30%, e.g., no more than 25%, or no more than 20%. In some embodiments, the contacting of the iron-based FT catalyst with the feed stream is performed with an oxygenated hydrocarbon selectivity (e.g., C2.8oxygenate selectivity) of no more than 15%, e.g., no more than 10%, or no more than 5%. In various embodiments as described herein, the contacting of the iron-based FT catalyst with the feed stream is performed with an oxygenated hydrocarbon selectivity (e.g., C2-8 oxygenate selectivity) in the range of 1-30%, e.g., in the range of 1-25%, or in the range of 1-20%, or in the range of 1-15%, or in the range of 1-10%, or in the range of 1-5%. In some embodiments, the contacting of the iron-based FT catalyst with the feed stream is performed with an oxygenated hydrocarbon selectivity (e.g., C2.8 oxygenate selectivity) in the range of 5-30%, e.g., in the range of 5-25%, or in the range of 5-20%, or in the range of 5- 15%, or in the range of 5-10%. As used herein, a “selectivity” for a given reaction product is the molar fraction of the relevant component of the feed (here, CO2) that is converted to the product (for “C5+ selectivity,” C5+). The present inventors have determined that the ironbased FT catalysts as described herein, even when operating at lower temperatures than many conventional FT catalysts, can provide excellent selectivity for C5+ hydrocarbons.

[0045] The present inventors have determined that the iron-based FT catalysts as described herein can provide desirably high C5+ selectivity at commercially relevant conversion rates. As used herein, a “conversion” is a molar fraction of a relevant component feed that is reacted (be it to desirable products or undesirable species). In various embodiments as described herein, the FT reaction has a CO2conversion of at least 5%, e.g., at least 10%, or at least 20%. For example, in some embodiments, the FT reaction has a CO2conversion of at least 30%, e.g., at least 40%, or at least 50%, or at least 60%. In various embodiments as described herein, the FT reaction has a CO2conversion of no more than 80%, e.g., no more than 70%. For example, in some embodiments, the FT reaction has a CO2conversion of no more than 65%, e.g., no more than 60%. For example, in various embodiments as otherwise described herein, the CO2conversion is in the range of 10-80%, e.g., 10-70%, or 10-60%, or 10-65%, or 20-80%, or 20-70%, or 20-60%, or 20-65%, or 30-80%, or 30-70%, or 30-60%, or 30-65%, or 40-80%, or 40-70%, or 40-60%, or 40- 65%. The person of ordinary skill in the art will, based on the disclosure herein, operate at adegree of conversion that provides a desirable product. And of course, in other embodiments, e.g., when in a stacked-bed or mixed-bed system, the effective CO2conversion may be even higher than described herein.

[0046] Advantageously, the FT processes as described herein can be performed at temperatures that are lower than temperatures used in many conventional FT processes. As such, in some embodiments, contacting of the feed stream with the iron-based FT catalyst in the reaction zone is conducted at a temperature in the in the range of 200-500°C. For example, in various embodiments, the contacting is conducted at an iron FT temperature in the range of 200-450 °C, e.g., 200-400 °C, or 200-350 °C, or 225-500 °C, or 225-450 °C, or 225-400 °C, of 225-350 °C, or 250-500 °C, or 250-450 °C, or 250-400 °C, or 250-350 °C, or 260-500 °C, or 260-450 °C, or 260-400 °C, or 260-350 °C, or 300-500 °C, or 300-450 °C, or 300-400 °C, or 300-350 °C. The present inventors have noted that operation at these temperatures can provide for lower energy demand, as well as for facile integration with a subsequent olefin oligomerization process as described herein.

[0047] Additionally, the FT processes as described herein can be performed at a variety of pressures, as would be appreciated by the person of ordinary skill in the art. In various embodiments, the process for performing the FT reaction is conducted at a pressure of at least 10 barg. For example, in various embodiments as described herein, the contacting the feed stream with an iron-based FT catalyst is conducted at a pressure of at least 20 barg, e.g., at least 30 barg, or at least 35 barg. In various embodiments of the present disclosure, the contacting is conducted at an iron FT pressure in the range of 1 to 100 barg. For example, the contacting is conducted at an iron FT pressure in the range of 1 to 80 barg, or 1 to 70 barg, or 1 to 60 barg, 5 to 100 barg, 5 to 80 barg, 5 to 70 barg, 5 to 60 bag, or 10 to 100 barg, 10 to 80 barg, or 10 to 70 barg, 10 to 60 barg. In some embodiments, the FT process is conducted at a pressure in the range of 10-60 barg, or 10-50 barg, or 10-40 barg, or 10-30 barg, or 10-20 barg, or 15-60 barg, or 15-50 barg, or 15-40 barg, or 15-30 barg, or 15-20 barg, or 20-60 barg, or 20-50 barg, or 20-40 barg, or 20-30 barg, 25-60 barg, or 25-50 barg, or 25-40 barg, or 25-30 barg.

[0048] The FT processes as described herein can be performed at a variety of GHSV (gas hourly space velocity), as would be appreciated by the person of ordinary skill in the art. As such, the GHSV for performing the FT reaction is not particularly limited. For example, in some embodiments, the process for performing the FT reaction is conducted at a GHSV in the range of 1 ,000 to 2,000,000 tr1. In various embodiments, the process for performing the FT reaction is conducted at a GHSV in the range of 1 ,000 to 1 ,200,000 h’1, or 1 ,000 to 500,000 h1, or 1 ,000 to 100,000 tr1, or 5,000 to 1 ,200,000 h1, or 5,000 to 500,000 tr1, or5,000 to 100,000 h’1, or 10,000 to 1 ,200,000 IT1, or 10,000 to 500,000 IT1, or 10,000 to 100,000 h-1. In various embodiments, the process for performing the FT reaction is conducted at a GHSV in the range of 1 ,000 to 50,000 IT1, or 2,000 to 50,000 IT1, or 5,000 to50,000 h’1, or 10,000 to 50,000, or 1 ,000 to 40,000 IT1, or 2,000 to 40,000 IT1, or 5,000 to40,000 h1, or 10,000 to 40,000 IT1, or 1 ,000 to 30,000 IT1, or 2,000 to 30,000 IT1, or 5,000 to30,000 h-1, or 10,000 to 30,000 h-1. Of course, the person of ordinary skill in the art will appreciate that other space velocities may be appropriate for particular processes. The present inventors note that the CO selectivity and C5+ selectivity of the iron FT process can depend in part on the GHSV at which the process is performed, with higher CO selectivities and lower C5+ selectivities typically resulting from higher GHSV values. The person of ordinary skill in the art would be able to determine a desired CO selectivity and C5+ productivity for a given iron FT process and select an appropriate GHSV for the iron FT process, appreciating that the full range of space velocities described above may not be available for a given iron FT process.

[0049] As noted above, due to the elevated temperatures required to achieve good CO2conversion to CO, the subsequent reaction of CO to hydrocarbons will produce light hydrocarbons that are highly olefinic, rather than the desired C5+ hydrocarbons. The present inventors have realized that the olefin oligomerization reaction can be used to convert those light olefins (e.g., C2-C4olefins) to heavy hydrocarbons (e.g., C5+ hydrocarbons) as C2-C4olefins can themselves be oligomerized to provide desired C5+ hydrocarbons, and thus increases the overall conversion of CO2in the process as described herein.

[0050] Accordingly, the process as described herein includes contacting at least a portion of the C2-C4olefins and the C5+ olefins formed by the contacting of the iron FT feed stream with an olefin oligomerization catalyst to provide oligomerized hydrocarbons, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst forms an FT- oligomerization product stream.

[0051] The olefin oligomerization catalysts as used herein are not particularly limited, and the person of ordinary skill in the art would be able to choose a catalyst as appropriate for the olefin oligomerization processes. In various embodiments as otherwise described herein, the olefin oligomerization catalyst is a zeolite-based catalyst. For example, in various embodiments, the olefin oligomerization catalyst is a zeolite of type USY, ZSM-5, ZSM-12, ZSM-22, MCM-22, and MCM-36. In various embodiments, the zeolite-based catalyst is metal-promoted. For example, the zeolite-based catalyst can be promoted with molybdenum or nickel. In various embodiments, the zeolite-based catalyst is ion-exchanged.For example, the zeolite-based catalyst can be ion-exchanged one or more of sodium, potassium, iron, zinc and gallium. But the person of ordinary skill in the art will appreciate that a variety of other materials can act as oligomerization catalysts, including a variety of crystalline and amorphous aluminosilicates (e.g., amorphous silica alumina) and silicoaluminophosphates. As the person of ordinary skill in a variety of modifications of the pore structure of the oligomerization catalyst may be made, e.g., to improve accessibility and slow deactivation by adding mesoporosity to otherwise microporous materials.

[0052] 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 olefin oligomerization processes. In various embodiments as described herein, the temperature for the olefin oligomerization process is in the range of 150-300 °C, e.g., in the range of I SO- 275 °C, or 150-250 °C.

[0053] Additionally, the olefin oligomerization processes as described herein can be performed at a variety of pressures, as would be appreciated by the person of ordinary skill in the art. In various embodiments, the process for performing the olefin oligomerization is conducted at a pressure in the range of 30-100 barg, or 30-90 barg, or 30-80 barg, or 30-70 barg, or 30-60 barg, or 30-50 barg, or 30-40 barg, or 40-100 barg, or 40-90 barg, or 40-80 barg, or 40-70 barg, or 40-60 barg, or 40-50 barg.

[0054] Notably, in many embodiments, the temperature for the FT process as described above and the temperature for the olefin oligomerization process as described herein can be relatively close to one another. As noted above, the present inventors have noted that the FT catalysts as described herein can provide suitable activity and C5+ selectivity even at relatively low temperatures. Accordingly, the FT product stream can be provided with a temperature that is suitable for, or at least close to suitable for, the olefin oligomerization process. This can desirably provide for increased process integration. For example, in various embodiments, the temperature for the FT process is within 100 °C of the temperature for the olefin oligomerization process, e.g., within 50 °C of the temperature for the olefin oligomerization process, or within 25 °C of the temperature for the olefin oligomerization process.

[0055] However, in other embodiments, the temperature for the FT process and the temperature for the olefin oligomerization process are less close to one another. The present inventors have noted that in many cases a desirable temperature for the FT process will be significantly greater than a desirable temperature for the olefin oligomerization process. For example, in various embodiments, the temperature for the FT process is at least 100 °C greater than the temperature for the olefin oligomerization process, e.g., atleast 150 °C greater than the temperature for the olefin oligomerization process, or at least 200 °C greater than the temperature for the olefin oligomerization process. The excess heat in the iron FT product stream can be used for a number of purposes, for example, to preheat at least part of the iron FT feed stream or to generate steam for use in generating electricity, as described above.

[0056] The olefin oligomerization process as 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 olefin oligomerization process is not particularly limited. For example, in some embodiments, the process for performing the olefin oligomerization process is conducted at a GHSV in the range of 100 to 2,000,000 h’1. In various embodiments, the process for performing the olefin oligomerization process is conducted at a GHSV in the range of 100 to 1 ,200,000 h-1, or 100 to 500,000 h-1, or 100 to 100,000 h’1, or 500 to 1 ,200,000 h’1, or 500 to 500,000 h’1, or 500 to 100,000 h’1, or 1 ,000 to 1 ,200,000 h’1, or 1 ,000 to 500,000 tr1, or 1 ,000 to 100,000 IT1. In various embodiments, the process for performing the olefin oligomerization process is conducted at a GHSV in the range of 100 to 50,000 IT1, or 500 to 50,000 h’1, or 1 ,000 to 50,000 h’1, or 5,000 to 50,000, or 500 to 40,000 IT1, or 1 ,000 to 40,000 IT1, or 1 ,000 to 40,000 IT1, or 5,000 to 40,000 h’1, or 100 to 30,000 IT1, or 500 to 30,000 IT1, or 1 ,000 to 30,000 IT1, or 2,000 to 30,000 h-1. The person of ordinary skill in the art will appreciate that other space velocities may be suitable in some cases.

[0057] In various embodiments as otherwise described herein, the contacting of the iron FT feed stream with the iron-based FT catalyst is performed in an FT reaction zone, the contacting forming an iron FT product stream comprising the C1-C4 hydrocarbons comprising C2-C4 olefins and C5+ hydrocarbons comprising C5+ olefins. In some embodiments as described herein, the process further comprises including at least a portion of the C2-C4 olefins and the C5+ olefins of the iron FT product stream in an olefin oligomerization feed stream, and in an olefin oligomerization reaction zone, contacting the olefin oligomerization feed stream with the olefin oligomerization catalyst under conditions sufficient to form the FT-oligomerization product stream.

[0058] The process as described herein can be operated in a wide variety of reactor systems. The reactors used for the integrated process as described herein are not particularly limited, and the person of ordinary skill in the art will be able to select an appropriate reactor. For example, in some embodiments as described herein, the iron FT reaction zone and the olefin oligomerization reaction zone are in separate reactors. In some embodiments, a first reaction zone (i.e., in which the FT process is performed) comprises afirst reactor in which an iron-based FT catalyst is disposed, and a second reaction zone (i.e., in which the olefin oligomerization process is performed) comprises a second reactor in which the olefin oligomerization catalyst is disposed. An example of such a process are shown schematically in FIG. 2. In the embodiment of FIG. 2, the process 200 is performed in a reactor system that includes a first reactor 210 in which an iron-based FT catalyst 213 is disposed, and a second reactor 220 in which the olefin oligomerization catalyst 223 is disposed. For example, the process 200 includes performing an FT reaction by providing an iron FT feed stream 211 comprising CO2and H2to a first reaction zone, e.g., a first reactor 210. An iron-based FT catalyst 213, as described herein, is provided in the first reaction zone and is contacted at a temperature and at a pressure with the iron FT feed stream 211 to provide an iron FT product stream 212 comprising heavy hydrocarbons (e.g., C5+ hydrocarbons comprising C5+ olefins) and light hydrocarbons (e.g., Ci-C4hydrocarbons comprising C2-C4 olefins). To convert the light hydrocarbons to additional heavy hydrocarbons, the process 200 further includes performing an olefin oligomerization reaction by providing an olefin oligomerization feed stream 211 comprising at least a portion of the C2-C4olefins and the C5+ olefins to a second reaction zone, e.g., a second reactor 220. In various embodiments, substantially all of the iron FT product stream is provided to the olefin oligomerization feed stream. An olefin oligomerization catalyst 223, as described herein, is provided in the second reaction zone and is contacted at a temperature and at a pressure with the olefin oligomerization stream 221 to provide an FT-oligomerization product stream 222 comprising hydrocarbons.

[0059] Other embodiments are possible. In some embodiments as described herein, the iron FT reaction zone and the olefin oligomerization reaction zone are within the same reactor e.g., as separate beds within the same reactor. For example, in some embodiments, the process is performed in a reactor system comprising a first catalyst bed in which an ironbased FT catalyst is disposed, and wherein the second reaction zone comprises a second catalyst bed in which the olefin oligomerization catalyst is disposed. In some embodiments, the first reactor bed and the second reactor bed are disposed within the same reactor. Such a configuration is schematically shown in FIG. 3, in which the iron-based FT catalyst 313 is disposed in a first catalyst bed 314, and the olefin oligomerization catalyst is disposed in a second catalyst bed 324. Here, the catalyst beds 314 and 324 are in the same reactor, with process gases flowing between them. In the process 300 of FIG. 3, the iron FT feed stream 311 , reactor 305, iron FT catalyst 313, olefin oligomerization catalyst 323, catalyst beds (314, 324), FT-oligomerization feed 322, separation zone 350, light product stream 336, heavy product stream 352, and recycle stream 338 are as described herein. Such aconfiguration can be especially desirable when the temperature for the FT process and the temperature for the olefin oligomerization are relatively close to one another.

[0060] In various embodiments, the process is performed in a reactor system comprising one or more first catalyst containers in which the iron-based FT catalyst is disposed, and wherein the second reaction zone comprises one or more second catalyst containers in which the olefin oligomerization catalyst is disposed. These can be provided in the same reactor, such as described above with respect to catalyst beds.

[0061] The person of ordinary skill in the art would, based on the present disclosure, appreciate that the iron FT product stream as described herein may include CO2, H2, CO, water, and other components in various amounts. Components of the iron FT product stream may be separated and used for various purposes in the FT process.

[0062] For example, in various embodiments as described herein, the process further includes separating the iron FT product stream to recycle at least a portion (e.g., at least 5 mol%, at least 10 mol%, at least 25 mol%, at least 50 mol%, at least 75 mol%, or at least 90 mol%) of the one or more components of the iron FT product stream to the iron FT feed stream. For example, when the iron FT product stream includes CO2, the process can include recycling at least a portion (e.g., at least 5 mol%, at least 10 mol%, at least 25 mol%, at least 50 mol%, at least 75 mol%, or at least 90 mol%) of the CO2in the iron FT product stream to the iron FT feed stream. The iron FT product stream may also include H2, and thus, in some embodiments, the process further includes recycling at least a portion of H2in the iron FT product stream (e.g., at least 5 mol%, at least 10 mol%, at least 25 mol%, at least 50 mol%, at least 75 mol%, or at least 90 mol%) to the iron FT feed stream.

[0063] Such recycling is shown schematically in the process 200 of FIG. 2. Here, the process 200 includes separating from iron FT product stream 212 at least a portion of CO2(stream 214) to recycle to the iron FT feed stream 211 . Similarly, the process 200 includes separating from the iron FT product stream 212 at least a portion of H2(stream 215) to recycle to the iron FT feed stream 211 . While stream 215 is depicted as entering reactor 210 through a different inlet than the rest of the iron FT feed stream 211 , it is considered to be part of the iron FT feed stream, as it is part of the material input to the FT process as described herein.

[0064] As noted above, the iron FT product stream may include water. In many cases, it can be desirable to reduce the amount of water that is provided to the olefin oligomerization process as described below. Accordingly, in various embodiments as otherwise described herein, the process further includes removing at least a portion (e.g., at least 25%, at least 50%, or at least 75%) of the water from the iron FT product stream. In the embodiment ofFIG. 2, a water stream 216 contains water removed from the iron FT product stream 212. The person of ordinary skill in the art will appreciate that a variety of processes can be used to remove water from the iron FT product stream. For example, the iron FT product stream can be contacted with a water scavenger to remove water therefrom. For example, a molecular sieve guard bed can be used to remove water from the iron FT product stream, where water can be recovered from the molecular sieves of the guard bed, e.g., by heating and vacuum. In other embodiments, a knockout vessel can be used to remove water (described in detail below). However, use of a knockout vessel can in some cases cool the FT product stream enough so that it is desirably reheated for introduction to the subsequent olefin oligomerization process.

[0065] Of course, when the oligomerization process is conducted in the same reactor as the FT process, it may be difficult to prevent water from reaching the oligomerization catalysts. In such cases, when the oligomerization process is conducted at a relatively hot temperature, e.g., at a similar temperature to the FT process, the water may slow down the deactivation of the oligomerization catalyst by reacting with carbon deposits thereon.

[0066] In various embodiments, the process further includes passing any portions of the iron FT product stream that are contacted with the olefin oligomerization catalyst through a guard bed before contacting with the olefin oligomerization catalyst. As noted above, the iron FT product stream may include water. Accordingly, by using a guard bed, the water in the iron FT product stream can be removed before the iron FT product stream contacts the olefin oligomerization catalyst.

[0067] The FT 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). Accordingly, in various embodiments as otherwise described herein, contacting the iron FT feed stream with an iron-based FT catalyst at a temperature and at a pressure provides an iron FT product stream comprising C5+ hydrocarbons. For example, contacting the iron FT feed stream with an iron-based FT catalyst at a temperature and at a pressure provides an iron FT product stream comprising C5+ hydrocarbons (e.g., C5+ olefins) of at least 30%, e.g., at least 50%, or at least 70%. In some embodiments, the overall olefin selectivity is at least 30%, e.g., at least 35%, or at least 40%.

[0068] Additional components may be present in the iron FT product stream. For example, in some embodiments, the iron FT product stream includes water, which is another product of an FT reaction. In some embodiments, the iron FT product stream includes one or more light hydrocarbons (e.g., C1-C4 hydrocarbons) as a side product. CO2or other inertsas described herein can also be present. Such components of the iron FT product stream can be separated and / or recycled in various manners.

[0069] The iron FT product stream may also include CO. In some embodiments, the CO is unreacted from the iron FT feed stream. In some other embodiments, the CO is from the contacting of the iron FT feed stream with the iron-based FT catalyst as described herein. Accordingly, in various embodiments, the process further includes contacting the CO and H2with a cobalt-based FT catalyst to convert the CO to additional C5+ hydrocarbons.

[0070] As described above, oxygenated hydrocarbons may also present in the iron FT product stream. Accordingly, in various embodiments as otherwise described herein, the Cr C4hydrocarbons and / or the C5+ hydrocarbons formed by the contacting of the iron FT feed stream with the iron-based FT catalyst comprise oxygenated hydrocarbons. Thus, in some embodiments, the process further comprises contacting at least a portion of the oxygenated hydrocarbons with a dehydration catalyst under conditions sufficient to provide additional C2- C4olefins and / or C5+ olefins, which can be provided to the subsequent olefin oligomerization process as described herein. In some other embodiments, the process further comprises contacting at least a portion of the oxygenated hydrocarbons and hydrogen with a hydrodeoxygenation catalyst under conditions sufficient to provide additional C2-C4olefins and / or C5+ olefins, which can be provided to the subsequent olefin oligomerization process as described herein.

[0071] Appropriate dehydration reaction conditions and dehydration catalysts can be chosen by the person of ordinary skill in the art. Examples of dehydration processes and catalysts are described in U.S. Patent Nos. 7,465,845, 4,677,242, and 4,440,871 , each of which is incorporated herein by reference in its entirety.

[0072] In various embodiments, the dehydration catalyst is a zeolite or a non-zeolite molecular sieve. For example, in some embodiments, the dehydration catalyst comprises a zeolite having AEI, AEL, BEA, CHA, EDI, FAU, FER, GIS, LTA, LTL, MER, MFI, MOR, MWW, TAM, or TON topology. In some embodiments, the dehydration catalyst comprises a molecular sieve containing silicon, aluminum, and / or phosphorus, e.g., aluminophosphate (ALPO) molecular sieves, or silicoaluminophosphate (SAPO) molecular sieves. In various embodiments, the dehydration catalyst further comprises cobalt, chromium, copper, iron, gallium, germanium, magnesium, manganese, nickel, tin, titanium, zinc, zirconium, or a mixture thereof.

[0073] In some embodiments, the contacting of the oxygenated hydrocarbons with the dehydration catalyst is performed at a dehydration temperature in the range of 250-800 °C, e.g., in the range of 250-750 °C, or in the range of 300-650 °C, or in the range of 350-600°C, or in the range of 400-500 °C. In some embodiments, the contacting of the oxygenated hydrocarbons with the dehydration catalyst is performed at a dehydration pressure in the range of 0.001 to 50 barg, e.g., in the range of 0.05 to 10 barg, or in the range of 0.2 to 5 barg. In some embodiments, the contacting of the oxygenated hydrocarbons with the dehydration catalyst is performed at a dehydration weight hourly space velocity (WHSV) in the range of 1-5000 h-1, e.g., in the range of 2-3000 tr1, or in the range of 5-1500 h-1, or in the range of 10-1000 h’1.

[0074] Appropriate hydrodeoxygenation reaction conditions and hydrodeoxygenation catalysts can be chosen by the person of ordinary skill in the art. Examples of hydrodeoxygenation processes and catalysts are described in U.S. Patent Nos. 8,795,392 and 4,313,852, each of which is incorporated herein by reference in its entirety.

[0075] In various embodiments, the hydrodeoxygenation catalyst comprises a porous carrier and an active metal component, present in an amount in the range of 1 to 20 wt% of, calculated on an oxide basis. In various embodiments, the porous carrier includes alumina, phosphorus in an amount in the range 0.001 to 1 wt%, and silica in an amount in the range of 0.001 to 1 wt%, calculated on an oxide basis. In various embodiments, the active metal component comprises at least one Group VIB metal (e.g., molybdenum) and at least one Group VIII metal (e.g., nickel). In various embodiments, the hydrodeoxygenation catalyst is sulfided.

[0076] In some embodiments, the contacting of the oxygenated hydrocarbons with the hydrodeoxygenation catalyst is performed at a hydrodeoxygenation temperature in the range of 250-400 °C, e.g., in the range of 250-350 °C, or in the range of 250-300 °C, or in the range of 300-400 °C, or in the range of 350-400 °C, or in the range of 300-350 °C, or in the range of 280-380 °C. The person of ordinary skill in the art will appreciate that hydrogen can be present in the atmosphere during hydrodeoxygenation. In some embodiments, the contacting of the oxygenated hydrocarbons with the hydrodeoxygenation catalyst is performed at a hydrogen partial pressure in the range of 10-220 barg, e.g., in the range of 10-200 barg, or 10-180 barg, or 10-160 barg, or 10-140 barg, or 10-120 barg, or 10-100 barg. In some embodiments, the contacting of the oxygenated hydrocarbons with the dehydration catalyst is performed at a hydrodeoxygenation liquid hourly space velocity (LHSV) in the range of 0.1 to 10 h’1, e.g., in the range of 0.1 to 8 h’1, or in the range of 0.1 to 5 h-1, or in the range of 0.1 to 2 IT1, or in the range of 0.2 to 10 IT1, or in the range of 0.2 to 8 h-1, or in the range of 0.2 to 5 h-1, or in the range of 0.2 to 2 IT1.

[0077] The contacting of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst can desirably convert the oxygenated hydrocarbons intoadditional C2-C4 olefins and C5+ olefins. In various embodiments as described herein, contacting of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst can be performed with an oxygenated hydrocarbon conversion of at least 20%, e.g., at least 30%, or at least 40%. In various embodiments, contacting of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst can be performed with an olefin selectivity (i.e., a combined selectivity for providing C2-C4olefins and C5+ olefins) of at least 60%, e.g., at least 70%, or at least 80%, as determined on a weight basis.

[0078] Accordingly, in various embodiments, the process further comprises after contacting the iron FT feed stream with an iron-based FT catalyst and prior to contacting at least a portion of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalysts contacting at least a portion of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst to provide additional C2-C4olefins and C5+ olefins, as depicted schematically in FIG. 6. In this example, the process 600 is performed in a reactor 605 comprising an iron FT reaction zone 610 containing iron-based FT catalyst 613 in an iron-based FT catalyst bed 614, a dehydration and / or hydrodeoxygenation reaction zone 640 containing dehydration and / or hydrodeoxygenation catalyst 643 in a dehydration and / or hydrodeoxygenation catalyst bed 644, and an olefin oligomerization reaction zone containing olefin oligomerization catalyst 623 in olefin oligomerization catalyst bed 624. In the process 600, the iron FT feed stream 611 is contacted with iron-based FT catalyst 613 to provide iron FT product stream 621 comprising C2-C4olefins, C5+ hydrocarbons comprising C5+ olefins, and oxygenated hydrocarbons. At least a portion of the oxygenated hydrocarbons of stream621 is provided as a stream 641 to contact the dehydration and / or hydrodeoxygenation catalyst 643 to provide additional C2-C4olefins and C5+ olefins in stream 642. At least a portion of C2-C4olefins and C5+ olefins from stream 621 and at least a portion of the additional C2-C4olefins and C5+ olefins from stream 642 are provided as olefin oligomerization stream 621 , which is contacted with olefin oligomerization catalyst 623 to provide an FT-oligomerization product stream 622. The FT-oligomerization product stream622 is conducted to separation zone 650, where it is separated into a light product stream 636, which is rich in hydrogen, carbon monoxide, carbon dioxide, and Ci-C4hydrocarbons (including C2-C4olefins); and a heavy product stream 652, which is rich in water and C5+ hydrocarbons. At least a portion of the C2-C4olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream 636 can be recycled to the iron FT feed stream 611 via recycle stream 638.

[0079] As further noted above, the FT process and the olefin oligomerization process can be performed under similar conditions. Accordingly, in various embodiments, the contacting of the iron FT feed with the iron-based FT catalyst and the contacting of the C2-C4 olefins and C5+ olefins with the olefin oligomerization catalyst is performed in a combination reaction zone comprising a mixture of the iron-based FT catalyst and the olefin oligomerization catalyst. For example, in some embodiments, the iron-based FT catalyst and the olefin oligomerization catalyst can be provided together in the same catalyst bed, e.g., mixed together. Such an embodiment is shown schematically in FIGS. 1 and 4. In these examples, the process (100, 400) is performed in a reactor system that includes a reactor (105, 405) in which the iron-based FT catalyst (113, 413) and the olefin oligomerization catalyst (123, 423) are mixed together in a single catalyst bed (124, 424). Here, the iron FT feed stream (111 , 411) and the FT-oligomerization product stream (122, 422) can be substantially the same as described herein.

[0080] In various embodiments, the mixture of the iron-based FT catalyst and the olefin oligomerization catalyst in the combination reaction zone is substantially homogeneous, e.g., as shown schematically in FIG. 1. In other various embodiments, the mixture of the ironbased FT catalyst and the olefin oligomerization catalyst in the combination reaction zone is substantially inhomogeneous with at least one gradient of increasing olefin oligomerization catalyst content in an upstream-to-downstream direction, e.g., as shown schematically in FIG. 4. In the process 400 of FIG. 4, the iron FT feed stream 411 , reactor 405, iron FT catalyst 413, olefin oligomerization catalyst 423, catalyst bed 424, FT-oligomerization feed 422, separation zone 450, light product stream 436, heavy product stream 452, and recycle stream 438 are as described herein.

[0081] In various embodiments as otherwise described herein, the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4 olefins and the C5+ olefins with the olefin oligomerization catalyst in the combination reaction zone are conducted at a temperature in the range of 260-350 °C, e.g., in the range of 260-330 °C, or 260-310 °C, or 260-300 °C; and at a pressure of at least 10 barg, e.g., in the range of IQ- 120 barg.

[0082] The process as described herein provides an FT-oligomerization product stream that includes oligomerized hydrocarbons. Accordingly, in various embodiments, one or more products are provided from at least a portion of the oligomerized hydrocarbons of the FT- oligomerization product stream. The oligomerized hydrocarbons can be used as the basis of a variety of fuels, e.g., gasoline, diesel, and aviation fuel. Other products, like waxes and lubricants, can also be made from the oligomerized hydrocarbons. Additionally, alkenes and oxygenates can be used as feedstocks in a variety of other processes.

[0083] The person of ordinary skill in the art will use conventional post-processing techniques to convert the oligomerized hydrocarbons to desirable C5+ products. Forexample, in various embodiments, the process further includes hydroprocessing at least a portion of the oligomerized hydrocarbons of the FT-oligomerization 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 accordingly.

[0084] The process as described herein further includes in a separation zone, separating the FT-oligomerization product stream to provide a light product stream rich in hydrogen, carbon monoxide, carbon dioxide, and C1-C4 hydrocarbons (including C2-C4olefins); and a heavy product stream rich in water and C5+ hydrocarbons. Such a process is shown schematically in FIGS. 2, 3, 4, and 5. In these examples, the process (200, 300, 400) includes a separation zone (250, 350, 450), in which the FT-oligomerization product stream (222, 322, 422) is separated to provide a light product stream (236, 336, 436) rich in hydrogen, carbon monoxide, carbon dioxide, and C1-C4 hydrocarbons (including C2-C4 olefins); and a heavy product stream (252, 352, 452) rich in water and C5+ hydrocarbons.

[0085] The person of ordinary skill in the art will appreciate that a variety of processes can be used to remove water from the heavy product stream. For example, the heavy product stream can be contacted with a water scavenger to remove water therefrom. For example, a molecular sieve guard bed can be used to remove water from the heavy product stream; water can be recovered from the molecular sieves of the guard bed, e.g., by heating and vacuum.

[0086] In various embodiments as otherwise described herein, the separation of the FT- oligomerization product stream is performed by cooling to condense water and C5+ hydrocarbons, e.g., in a knockout vessel. For example, in various embodiments, the separation performed by cooling is conducted in a respective cooling loop comprising a heat exchanger, a condenser, and a product separation vessel, wherein the FT-oligomerization product stream is conducted through the heat exchanger; conducted through the condenser where water and C5+ hydrocarbons are condensed; and conducted to the product separation vessel from which the respective water-rich product stream (e.g., the heavy product stream) is separated from the respective water-poor product stream (e.g., the light product stream). An example of such a process is shown in FIG. 5. In the separation zone 550 of FIG. 5, the separation is performed in a respective cooling loop comprising a heat exchanger 530, a condenser 532, and a product separation vessel 534, wherein a product stream 522 (e.g., the FT-oligomerization product stream as described herein) is conducted through the heat exchanger 530; conducted through the condenser 532 where water 533a and C5+hydrocarbons 533b are condensed; and conducted to the product separation vessel 534 from which the respective water-rich product stream 552 (e.g., the heavy product stream as described herein) is separated from the respective water-poor product stream 536 (e.g., the light product stream as described herein). In some cases, when the separation is performed by cooling, the product streams are cooled enough so that it is desirably reheated for introduction to the next process step.

[0087] Accordingly, in various embodiments, the light product stream includes no more than 25% of the water of the FT-oligomerization product stream, e.g., no more than 20%, or no more than 15%. In various other embodiments, the light product stream includes no more than 25 wt% of the C5+ hydrocarbons of the FT-oligomerization product stream, e.g., no more than 20 wt%, or no more than 15 wt%.

[0088] Additionally, in various embodiments, the hydrocarbon content of the heavy product stream has an average carbon number of at least 8 carbons per molecule. In various other embodiments, the C5+ hydrocarbons of the heavy product stream are provided at an overall selectivity (i.e., from converted oxides of carbon input) of at least 70%, e.g., at least 80%, or at least 85%.

[0089] CO may be present in the FT-oligomerization product stream. Accordingly, in various embodiments, the process further includes contacting the CO with H2and in the presence of a cobalt-based FT catalyst to convert the CO to additional C5+ hydrocarbons. In some embodiments, the contacting of the CO and H2with the cobalt-based FT catalyst is performed in a cobalt FT reaction zone downstream of the olefin oligomerization catalyst. In some other embodiments, the contacting of the CO and H2with the cobalt-based FT catalyst is performed in an olefin oligomerization reaction zone, e.g., with the cobalt-based FT catalyst being admixed with the olefin oligomerization catalyst.

[0090] The person of ordinary skill in the art would appreciate that, based on the processes as described herein, the light product stream may include H2, CO, and CO2in addition to Ci-C4hydrocarbons. These components may be separated and used for various purposes in the processes as described herein.

[0091] Accordingly, in various embodiments, the process further includes including at least a portion of the C2-C4olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream to the iron FT feed stream. For example, in various embodiments, the process includes including at least a portion (e.g., at least 5 mol%, or at least 10 mol%, or at least 25 mol%) of the C2-C4olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream to the iron FT feed stream. For example, the process can include recycling at least a portion (e.g., at least 5 mol%, or at least 10 mol%, or at least 25 mol%) ofthe C2-C4 olefins of the light product stream to the iron FT feed stream. When the light product stream includes H2, the process can include recycling at least a portion (e.g., at least 5 mol%, or at least 10 mol%, or at least 25 mol%) of the H2of the light product stream to the iron FT feed stream. The light product stream may also include CO; and in these embodiments, the process can include recycling at least a portion (e.g., at least 5 mol%, or at least 10 mol%, or at least 25 mol%) of the CO of the light product stream to the iron FT feed stream. The light product stream may also include CO2; and these embodiments, the process can include recycling at least a portion (e.g., at least 5 mol%, or at least 10 mol%, or at least 25 mol%) of the CO2of the light product stream to the iron FT feed stream.

[0092] Such recycling processes are shown schematically in the process (100, 200, 300, 400) of FIGS. 1 , 2, 3, and 4. Here, the process (100, 200, 300, 400) includes including at least a portion of the C2-C4olefins, hydrogen, carbon monoxide, and / or carbon dioxide (indicated by stream 138, 238, 338, 438) of the light product stream to the iron FT feed stream (135, 236, 336, 436), which then becomes part of the iron FT fed stream (1111 , 211 , 311 , 411).

[0093] Of course, there are other uses for the light hydrocarbons. For example, in some embodiments, the process further comprises oxidizing at least a portion of the light product stream to provide a CO- and / or C02-containing partial oxidation (pOX) stream, and including at least a portion of the pOX stream in the iron FT feed stream. 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.

[0094] As described above, CO2and H2are substantial inputs to the processes as described herein. Advantageously, the present inventors have recognized that each of these can come from renewable or otherwise environmentally responsible sources.

[0095] For example, CO2can generally be captured from the environment, or more directly from processes that form CO2(especially in difficult-to-abate sectors). This can make the eventual hydrocarbon product substantially carbon-neutral or of lower carbon intensity. Accordingly, in some embodiments as described herein, at least a part of the CO2of the iron FT feed stream is from a renewable source. In some embodiments, at least part (e.g., at least 25%, at least 50%, or at least 75%) of the CO2of the iron FT feed stream is from direct air capture. In some embodiments, at least part (e.g., at least 25%, at least 50%, or at least 75%) of the CO2of the iron FT feed stream is from a manufacturing plant such as a bioethanol plant (e.g., CO2produced fermentation), a steel plant, or a cement plant.Accordingly, the integrated process as described herein can be not only carbon neutral, but in some cases, a net consumer of carbon dioxide. These benefits, in particular, make theintegrated process highly attractive for decarbonizing transportation fuels, for both automotive and aviation sectors.

[0096] Similarly, H2can be provided from environmentally-responsible sources. In some embodiments, at least a part of the H2of the iron FT 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 iron FT 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 iron FT 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 iron FT feed stream is grey hydrogen, black hydrogen, brown hydrogen, pink hydrogen, turquoise hydrogen, yellow hydrogen, and / or white hydrogen.

[0097] 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 process for preparing hydrocarbons, the process comprising: providing an iron Fischer-Tropsch (FT) feed stream comprising carbon dioxide and hydrogen, the iron FT feed stream comprising no more than 10 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%; contacting the iron FT feed stream with an iron-based FT catalyst under conditions sufficient to form Ci-C4hydrocarbons comprising C2-C4olefins and C5+ hydrocarbons comprising C5+ olefins; contacting at least a portion of the C2-C4olefins and the C5+ olefins formed by the contacting of the iron FT feed stream with an olefin oligomerization catalyst to provide oligomerized hydrocarbons, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst forms an FT-oligomerization product stream; in a separation zone, separating the FT-oligomerization product stream to provide a light product stream rich in hydrogen, carbon monoxide, carbon dioxide, and Cr C4hydrocarbons (including C2-C4olefins); and a heavy product stream rich in water and C5+ hydrocarbons; andincluding at least a portion of the C2-C4 olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream in the iron FT feed stream.Embodiment 2. The process of embodiment 1 , wherein the light product stream includes no more than 25% of the water of the FT-oligomerization product stream, e.g., no more than 20%, or no more than 15%.Embodiment 3. The process of embodiment 1 , wherein the light product stream includes no more than 25 wt% of the C5+ hydrocarbons of the FT-oligomerization product stream, e.g., no more than 20 wt%, or no more than 15 wt%.Embodiment 4. The process according to any of embodiments 1-3, wherein the separation of the FT-oligomerization product stream is performed by cooling to condense water and C5+ hydrocarbons.Embodiment 5. The process according to any of embodiments 1-4, wherein the hydrocarbon content of the heavy product stream has an average carbon number of at least 8 carbons per molecule.Embodiment 6. The process according to any of embodiments 1-5, wherein the ironbased FT catalyst is an alkali-promoted iron FT catalyst.Embodiment 7. The process according to any of embodiments 1-6, wherein the olefin oligomerization catalyst is a zeolite-based catalyst, e.g., based on a zeolite of type USY, ZSM-5, ZSM-12, ZSM-22, MCM-22, and MCM-36.Embodiment 8. The process of embodiment 7, wherein the zeolite-based catalyst is metal-promoted, e.g., with molybdenum or nickel.Embodiment 9. The process of embodiment 7 or embodiment 8, wherein the zeolitebased catalyst is ion-exchanged, e.g., with one or more of sodium, potassium, iron, zinc and gallium.Embodiment 10. The process according to any of embodiments 1-6, wherein the olefin oligomerization catalyst is an amorphous silica alumina catalyst.Embodiment 11. The process according to any of embodiments 1-10, wherein the iron FT feed stream has a ratio of hydrogen to oxides of carbon in the range of 1 :1 to 6:1 , e.g., 1.5:1 to 3:1 .Embodiment 12. The process according to any of embodiments 1-11 , wherein the iron FT feed stream has no more than 8 wt% water, e.g., no more than 5 wt%, or no more than 2 wt%, or no more than 1 wt%.Embodiment 13. The process according to any of embodiments 1 -12, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4 olefins and the C5+ olefins with the olefin oligomerization catalyst is performed in a combination reaction zone comprising a mixture of the iron-based FT catalyst and the olefin oligomerization catalyst.Embodiment 14. The process of embodiment 13, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4 olefins and the C5+ olefins with the olefin oligomerization catalyst in the combination reaction zone are conducted at a temperature in the range of 260-350 °C, e.g., in the range of 260-330 °C, or 260-310 °C, or 260-300 °C.Embodiment 15. The process of embodiment 13 or embodiment 14, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4 olefins and the C5+ olefins with the olefin oligomerization catalyst in the combination reaction zone are conducted at a pressure of at least 10 barg, e.g., in the range of 10-120 barg.Embodiment 16. The process according to any of embodiments 13-15, wherein the C5+ hydrocarbons of the heavy product stream are provided at an overall selectivity (i.e., from converted oxides of carbon input) of at least 70%, e.g., at least 80%, or at least 85%.Embodiment 17. The process according to any of embodiments 13-16, wherein the mixture of the iron-based FT catalyst and the olefin oligomerization catalyst in the combination reaction zone is substantially homogeneous.Embodiment 18. The process according to any of embodiments 13-16, wherein the mixture of the iron-based FT catalyst and the olefin oligomerization catalyst in thecombination reaction zone is substantially inhomogeneous with at least one gradient of increasing olefin oligomerization catalyst content in an upstream-to-downstream direction.Embodiment 19. The process according to any of embodiments 1-12, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst is performed in an FT reaction zone, the contacting forming an iron FT product stream comprising the C1-C4 hydrocarbons comprising C2-C4olefins and C5+ hydrocarbons comprising C5+ olefins; and wherein the process further comprises including at least a portion of the C2-C4olefins and the C5+ olefins of the iron FT product stream in an olefin oligomerization feed stream; and in an olefin oligomerization reaction zone, contacting the olefin oligomerization feed stream with the olefin oligomerization catalyst under conditions sufficient to form the FT-oligomerization product stream.Embodiment 20. The process according to embodiment 19, wherein the FT reaction zone and the olefin oligomerization reaction zone are within the same reactor, e.g., as separate beds within the same reactor.Embodiment 21 . The process according to embodiment 19, wherein the FT reaction zone and the olefin oligomerization reaction zone are in separate reactors.Embodiment 22. The process according to any of embodiments 19-21 , wherein substantially all of the iron FT product stream is provided to the olefin oligomerization feed stream.Embodiment 23. The process according to any of embodiments 19-22, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst in the FT reaction zone is conducted at a temperature in the range of 260-350 °C, e.g., in the range of 260-330 °C, or 260-310 °C, or 260-300 °C.Embodiment 24. The process according to any of embodiments 19-23, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst in the FT reaction zone is conducted at a pressure of at least 10 barg, e.g., in the range of 10-60 barg.Embodiment 25. The process according to any of embodiments 19-24, wherein the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst inthe olefin oligomerization reaction zone is conducted at a temperature in the range of 150- 300 °C, e.g., in the range of 150-275 °C, or 150-250 °C.Embodiment 26. The process according to any of embodiments 19-24, wherein the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst in the olefin oligomerization reaction zone is conducted at a pressure in the range of 30-100 bar.Embodiment 27. The process according to any of embodiments 19-26, wherein the process includes passing any portions of the FT product stream that are contacted with the olefin oligomerization catalyst through a guard bed before contacting with the olefin oligomerization catalyst.Embodiment 28. The process according to any of embodiments 19-27, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst in the FT reaction zone is conducted with a C5+ selectivity of at least 45%, e.g., at least 50%, or at least 55%.Embodiment 29. The process according to any of embodiments 19-28, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst in the FT reaction zone is conducted with an overall olefin selectivity of at least 30% e.g., at least 35%, or at least 40%.Embodiment 30. The process of any of embodiments embodiment 1-29, wherein oxygenated hydrocarbons are formed when contacting the iron FT feed stream with an ironbased FT catalyst under conditions sufficient to form C1-C4 hydrocarbons comprising C2-C4olefins and C5+ hydrocarbons comprising C5+ olefins.Embodiment 31 . The process of embodiment 30, wherein the process further comprises, after contacting the iron FT feed stream with an iron-based FT catalyst and prior to contacting at least a portion of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalysts: contacting at least a portion of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst to provide additional C2-C4olefins and C5+ olefins.Embodiment 32. The process of embodiment 31 , wherein at least a portion of the additional C2-C4olefins and C5+ olefins provided by contacting of the oxygenated hydrocarbons with the dehydration and / or hydrodeoxygenation catalyst is contacted with the olefin oligomerization catalyst to provide oligomerized hydrocarbons.Embodiment 33. The process of embodiment 32, wherein the FT-oligomerization product stream includes the contacting of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst.Embodiment 34. The process according to any of embodiments 1-33, wherein the Cr C4hydrocarbons and / or the C5+ hydrocarbons formed by the contacting of the iron FT feed stream with the iron-based FT catalyst comprise oxygenated hydrocarbons, and wherein the process further comprises contacting the oxygenated hydrocarbons with a dehydration catalyst to provide additional C2-C4olefins and / or C5+ olefins that are contacted with the oligomerization catalyst.Embodiment 35. The process according to any of embodiments 1-34, wherein the Cr C4hydrocarbons and / or the C5+ hydrocarbons formed by the contacting of the iron FT feed stream with the iron-based FT catalyst comprise oxygenated hydrocarbons, and wherein the process further comprises contacting the oxygenated hydrocarbons and hydrogen with a hydrodeoxygenation catalyst to provide additional C2-C4olefins and / or C5+ olefins that are contacted with the oligomerization catalyst.Embodiment 36. The process according to any of embodiment 1-35, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst forms carbon monoxide, and wherein the process further comprises contacting the carbon monoxide and hydrogen with a cobalt-based FT catalyst to convert carbon monoxide to additional C5+ hydrocarbons.Embodiment 37. The process according to embodiment 36, wherein the contacting of the carbon monoxide and hydrogen with the cobalt-based FT catalyst is performed in a cobalt FT reaction zone downstream of the olefin oligomerization catalyst.Embodiment 38. The process according to embodiment 36, wherein the contacting of the carbon monoxide and hydrogen with the cobalt-based FT catalyst is performed in anolefin oligomerization reaction zone, e.g., with the cobalt-based FT catalyst being admixed with the olefin oligomerization catalyst.

[0098] 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 used herein is for the purpose of describing particular aspects only and, unless specifically defined herein, is not intended to be limiting.

[0099] 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 process 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.

[0100] 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.

[0101] 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 theplural 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.

[0102] 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.

[0103] Unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired 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.

[0104] 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.

[0105] 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.

[0106] 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 suchvariations 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.

[0107] 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:1 . A process for preparing hydrocarbons, the process comprising providing an iron Fischer-Tropsch (FT) feed stream comprising carbon dioxide and hydrogen, the iron FT feed stream comprising no more than 10 wt% water; contacting the iron FT feed stream with an iron-based FT catalyst under conditions sufficient to form C1-C4 hydrocarbons comprising C2-C4olefins, C5+ hydrocarbons comprising C5+ olefins, and oxygenated hydrocarbons; and contacting at least a portion of the oxygenated hydrocarbons with a dehydration and / or a hydrodeoxygenation catalyst to provide additional C2-C4olefins and C5+ olefins; then contacting at least a portion of the C2-C4olefins and the C5+ olefins formed by the contacting of the iron FT feed stream and at least a portion of the additional C2-C4olefins and C5+ olefins provided by contacting the oxygenated hydrocarbons with the dehydration and / or hydrodeoxygenation catalyst with an olefin oligomerization catalyst to provide oligomerized hydrocarbons, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst, the contacting of the oxygenated hydrocarbons with a dehydration and / or hydrodeoxygenation catalyst, and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst forms an FT-oligomerization product stream; in a separation zone, separating the FT-oligomerization product stream to provide a light product stream rich in hydrogen, carbon monoxide, carbon dioxide, and Cr C4hydrocarbons (including C2-C4olefins); and a heavy product stream rich in water and C5+ hydrocarbons; and including at least a portion of the C2-C4olefins, hydrogen, carbon monoxide, and carbon dioxide of the light product stream in the iron FT feed stream.

2. The process according to claim 1 , wherein the light product stream includes no more than 25% of the water and no more than 25 wt% of the C5+ hydrocarbons of the FT- oligomerization product stream.

3. The process according to claim 1 or claim 2, wherein the hydrocarbon content of the heavy product stream has an average carbon number of at least 8 carbons per molecule.

4. The process according to any of claims 1-3, wherein the iron-based FT catalyst is an alkali-promoted iron FT catalyst, and / or wherein the olefin oligomerization catalyst is azeolite-based catalyst, e.g., based on a zeolite of type USY, ZSM-5, ZSM-12, ZSM-22, MCM-22, and MCM-36, or an amorphous silica alumina catalyst.

5. The process according to any of claims 1-4, wherein the olefin oligomerization catalyst is a zeolite-based catalyst, e.g., based on a zeolite of type USY, ZSM-5, ZSM-12, ZSM-22, MCM-22, and MCM-36, or an amorphous silica alumina catalyst.

6. The process according to any of claims 1-5, wherein the iron FT feed stream has a ratio of hydrogen to oxides of carbon in the range of 1 :1 to 6:1 .

7. The process according to any of claims 1-6, wherein the iron FT feed stream has no more than 2 wt% water.

8. The process according to any of claims 1-7, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst is performed in a combination reaction zone comprising a mixture of the iron-based FT catalyst and the olefin oligomerization catalyst.

9. The process according to claim 8, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst and the contacting of the C2-C4olefins and the C5+ olefins with the olefin oligomerization catalyst in the combination reaction zone are conducted at a temperature in the range of 260-350 °C and / or at a pressure of at least 10 barg, e.g., in the range of 10-120 barg.

10. The process according to claim 8 or claim 9, wherein the C5+ hydrocarbons of the heavy product stream are provided at an overall selectivity (i.e., from converted oxides of carbon input) of at least 70%.11 . The process according to any of claims 8-10, wherein the mixture of the iron-based FT catalyst and the olefin oligomerization catalyst in the combination reaction zone is substantially homogeneous.

12. The process according to any of claims 8-10, wherein the mixture of the iron-based FT catalyst and the olefin oligomerization catalyst in the combination reaction zone issubstantially inhomogeneous with at least one gradient of increasing olefin oligomerization catalyst content in an upstream-to-downstream direction.

13. The process according to any of claims 1-7, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst is performed in an FT reaction zone, the contacting forming an iron FT product stream comprising the C1-C4 hydrocarbons comprising C2-C4 olefins and C5+ hydrocarbons comprising C5+ olefins; and wherein the process further comprises including at least a portion of the C2-C4olefins and the C5+ olefins of the iron FT product stream in an olefin oligomerization feed stream; and in an olefin oligomerization reaction zone, contacting the olefin oligomerization feed stream with the olefin oligomerization catalyst under conditions sufficient to form the FT-oligomerization product stream.

14. The process according to claim 13, wherein substantially all of the iron FT product stream is provided to the olefin oligomerization feed stream.

15. The process according to claim 13 or claim 14, wherein the contacting of the iron FT feed stream with the iron-based FT catalyst in the FT reaction zone is conducted with an overall olefin selectivity of at least 30%.

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