Processes for fischer-tropsch conversion of carbon dioxide to condensable hydrocarbons

Abstract

A process for preparing hydrocarbons includes providing a feed stream comprising H2, CO, and CO2; contacting the feed stream with an iron-based FT catalyst under conditions to form a product stream comprising C5+ hydrocarbons and CO; and recycling at least a portion of the CO of the product stream to the feed stream, wherein the feed stream has a H2 partial pressure expressed in bars (i.e., PH2), a CO2 partial pressure expressed in bars (i.e., PCO2), and a CO partial pressure expressed in bars (i.e., PCO) such that a value X as defined by the equation X = -80.9156 + 0.6891[PH2] + 79.6799[PCO2 / (PCO + PCO2)] + 42.3173[PH2 / (2PCO + 3PCO2)] is at least 0; on a plot of [PCO / PCO2] vs. [PH2 / (PCO + PCO2)], the point ([PH2 / (PCO + PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.16[PH2 / (PCO + PCO2)]; a ratio of [PCO / PCO2] is no greater than 1; and a ratio of [PH2 / (PCO + PCO2)] is no greater than 3.

Description

501730 23-1472-WO PROCESSES FOR FISCHER-TROPSCH CONVERSION OF CARBON DIOXIDE TO CONDENSABLE HYDROCARBONS CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority U.S. provisional application number 63 / 616,386, filed December 29, 2023 and European Patent application number 24166574.4, filed March 26, 2024, each of which is incorporated by reference herein in its entirety. 1. Field

[0002] The present disclosure relates generally to processes for the Fischer-Tropsch synthesis of hydrocarbons from carbon dioxide. 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. The Fischer- Tropsch reaction converts carbon monoxide to hydrocarbon products, as in the generalized reaction shown below: CO + 2 H2^ [-CH2-] + H2O The hydrocarbon products can be in the form of one or more of alkanes, alkenes and oxygenated hydrocarbons like alkanols.

[0004] The products of these FT processes 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. Olefins, alcohols, and other oxygenates obtained may also be used as reagents in other processes, such as in the synthesis of lubricants.

[0005] Currently, cobalt-based catalyst materials are the primary type of catalyst materials used in FT processes; they generally yield linear paraffins as primary products. Iron-based catalyst material materials are also known, and can be lower in cost compared to cobalt-based catalyst material materials. Iron-catalysed FT produces substantial amounts of501730 23-1472-WO long-chain α-olefins, which in many cases is a desirable product. Moreover, in contrast to cobalt, iron-based catalyst materials generally show 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 in an equilibrium process, as shown below: CO + H2O CO2+ H2CO2conversion on the iron- FT can convert CO2 to 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 CO2conversion towards C5+hydrocarbons while minimizing the undesirable effects of the high water-gas shift activity of iron-based catalysts. As such, there is a need to provide improved iron-based FT processes. SUMMARY

[0006] In one aspect, the present disclosure provides a process for preparing hydrocarbons. The process includes providing a feed stream comprising H2, CO, and CO2; contacting the feed stream with an iron-based FT catalyst under conditions to form a product stream comprising C5+hydrocarbons and CO; and recycling at least a portion of the CO of the product stream to the feed stream, wherein the feed stream has a H2partial pressure expressed in bars (i.e., PH2), a CO2partial pressure expressed in bars (i.e., PCO2), and a CO partial pressure expressed in bars (i.e., PCO) such that a value X as defined by the equation X = -80.9156 + 0.6891[PH2] + 79.6799[PCO2 / (PCO+ PCO2)] + 42.3173[PH2 / (2PCO+ 3PCO2)] is at least 0; on a plot of [PCO / PCO2] vs. [PH2 / (PCO+ PCO2)], the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.16[PH2 / (PCO+ PCO2)]; a ratio of [PCO / PCO2] is no greater than 1; and a ratio of [PH2 / (PCO+ PCO2)] is no greater than 3.

[0007] Other aspects of the disclosure will be apparent to the person of ordinary skill the art based on the disclosure herein.501730 23-1472-WO BRIEF DESCRIPTION OF FIGURES

[0008] 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.

[0009] FIG.1 is a graph of the CO / CO2ratio vs H2 / (CO + CO2) ratio providing an example of a desirable range of operation for high C5+selectivity in an iron-catalyzed Fischer-Tropsch process.

[0010] FIG.2 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0011] FIG.3 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0012] FIG.4 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0013] FIG.5 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0014] FIG.6 is a schematic of a process for performing a Fischer-Tropsch process as described herein.

[0015] FIG.7 is a graph of the C5+ selectivity vs %CO in the feed stream.

[0016] FIG.8 is a graph of the C5+ selectivity vs %CO in the feed stream.

[0017] FIG.9 is an illustration of the trends in C5+ selectivity vs %CO in the feed stream as described herein. DETAILED DESCRIPTION

[0018] 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. The present inventors have noted that there are various competing chemical reactions in such processes. One of the keys to the process is the water-gas shift activity of many iron-FT catalysts, which can beneficially convert CO2to CO (typically known as a “reverse water-gas shift”), which can be further reacted on the same catalyst in the Fischer-Tropsch reaction to form hydrocarbons. The water-gas shift reaction, however, is501730 23-1472-WO reversible, and so the counter-productive conversion of CO to CO2(i.e., in the so-called “forward” direction of the water-gas shift) is always possible, especially at lower temperatures, lower hydrogen partial pressures, higher water partial pressures and higher CO partial pressures. But while hydrogen is desirable from the standpoint of maintaining a net conversion of CO2to CO, and then on to desirable hydrocarbon products, too much hydrogen is also problematic in that it tends to provide products of lower molecular weight, i.e., less of the desirable C5+hydrocarbons and more of the less desirable C1-C4hydrocarbons. The complications here are exacerbated by the fact that there will typically be CO in the product stream from the Fischer-Tropsch reaction zone, which is desirably recycled to the feed, which provides increased CO concentration in the feed and thus a higher chance for the counterproductive forward water-gas shift of CO to CO2to dominate.

[0019] Here, the present inventors provide a process that provides increased net CO2conversion and provides high C5+selectivity for CO-recycling iron-FT CO2conversion processes through selection of particular partial pressures of H2, CO and CO2present in the feed stream. The present inventors have identified particular relative partial pressures for these constituents that tend to provide a highly desirable balance of all of these competing reactions to provide relatively high C5+selectivity and CO2conversion.

[0020] Accordingly, in one aspect, the present disclosure provides a process for preparing hydrocarbons from carbon dioxide. The process includes providing a feed stream comprising H2, CO, and CO2; contacting the feed stream with an iron-based FT catalyst under conditions to form a product stream comprising C5+hydrocarbons and CO; and recycling at least a portion of the CO of the product stream to the feed stream; the feed stream has a H2partial pressure expressed in bars (i.e., PH2), a CO2partial pressure expressed in bars (i.e., PCO2), and a CO partial pressure expressed in bars (i.e., PCO) such that a value X as defined by the equation X = -80.9156 + 0.6891[PH2] + 79.6799[PCO2 / (PCO+ PCO2)] + 42.3173[PH2 / (2PCO+ 3PCO2)] is at least 0; on a plot of [PCO / PCO2] vs. [PH2 / (PCO+ PCO2)], the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.16[PH2 / (PCO+ PCO2)]; a ratio of [PCO / PCO2] is no greater than 1; and a ratio of [PH2 / (PCO+ PCO2)] is no greater than 3.

[0021] These values are schematically illustrated in FIG.1, which provides a plot of [PCO / PCO2] vs. [PH2 / (PCO+ PCO2)] for a particular H2partial pressure. The limit of [PCO / PCO2] being no greater than 1 is represented by the top limit of the graph; a physical explanation for this is that having more CO than CO2present will tend to undesirably favor the forward water-gas shift reaction. The limit of [PH2 / (PCO+ PCO2)] being no greater than 3 is represented by the right-hand limit of the graph; a physical explanation for this is that higher501730 23-1472-WO relative H2partial pressures tends to limit the molecular weight of the product, providing increased amounts C1-C4hydrocarbons and decreased amounts of the desirable C5+hydrocarbons. A line representing values of X = 0 cordons off a section of the graph at the left-hand side. The position of this line will vary with H2partial pressure. A physical explanation for this is that when X is less than zero, there is generally no net CO2conversion; rather, CO is converted to CO2. And the line [PCO / PCO2] = 0.16[PH2 / (PCO+ PCO2)], is shown along the bottom edge of the graph. This cordons off a section of the graph at the bottom; a physical explanation for this is that below the line, high H2 / CO ratios lead to diminished C5+selectivities. Thus, these lines mark off a desirable region of operation, in which there is generally positive CO2conversion and good overall C5+selectivity.

[0022] As used herein, a “feed stream” is used to mean the total material input to a process step, regardless of whether provided in a single physical stream or multiple physical streams, and whether through a single inlet or multiple inlets. Here, the “feed stream” includes the material recycled from the product stream, and so the CO provided from the product stream is considered to be part of the feed stream. 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 reactor outlet or multiple reactor outlets. For example, hydrogen and carbon dioxide of the first feed stream can be provided to the iron-based FT catalyst material in a single physical stream (e.g., in a single pipe to reactor 110), or in multiple physical streams (e.g., separate inlets for carbon dioxide and H2, or one inlet for fresh carbon dioxide and H2and another for recycled carbon dioxide and / or H2). “Conversion” is defined as a net fraction of carbon dioxide that is converted to other species in the product stream, be it hydrocarbons of any size or CO.

[0023] The value X is related to the degree of CO2conversion, and is desirably made as high as reasonable will providing overall desirable product distribution and reaction conditions. In various embodiments as otherwise described herein, X is at least 1, e.g., at least 2 or at least 5. In various embodiments as otherwise described herein, X is at least 10, e.g., at least 15. In various embodiments as otherwise described herein, X is at least 20, e.g., at least 25 or at least 30. There will generally be an upper limit as to desirable values of X for a given process; the person of ordinary skill in the art can determine this based on the disclosure herein. For example, in various embodiments, X is no more than 60, e.g., no more than 55. In various embodiments, X is no more than 50, e.g., no more than 45. In various embodiments, X is no more than 40, e.g., no more than 35. A variety of ranges for X are thus possible; in various embodiments, X is in the range of 1-60, e.g., 1-55, or 1-50, or 1- 45, or 1-40, or 1-35. In various embodiments, X is in the range of 2-60, e.g., 2-55, or 2-50,501730 23-1472-WO or 2-45, or 2-40, or 2-35. In various embodiments, X is in the range of 5-60, e.g., 5-55, or 5- 50, or 5-45, or 5-40, or 5-35. In various embodiments, X is in the range of 10-60, e.g., 10- 55, or 10-50, or 10-45, or 10-40, or 10-35. In various embodiments, X is in the range of 20- 60, e.g., 20-55, or 20-50, or 20-45, or 20-40, or 20-35. In various embodiments, X is in the range of 25-60, e.g., 25-55, or 25-50, or 25-45, or 25-40, or 25-35. In various embodiments, X is in the range of 30-60, e.g., 30-55, or 30-50, or 30-45, or 30-40.

[0024] As described above, the interplay between PH2, PCOand PCO2can be complex. The present inventors have found that operating with a set of PH2, PCOand PCO2values selected such that on a plot of [PCO / PCO2] vs. [PH2 / (PCO+ PCO2)], the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.16[PH2 / (PCO+ PCO2)]. For example, in various embodiments, the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.17 [PH2 / (PCO+ PCO2)], e.g., above the line [PCO / PCO2] = 0.18 [PH2 / (PCO+ PCO2)]. In various embodiments, the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.19 [PH2 / (PCO+ PCO2)], e.g., above the line [PCO / PCO2] = 0.20 [PH2 / (PCO+ PCO2)]. In various embodiments, the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.21 [PH2 / (PCO+ PCO2)], e.g., above the line [PCO / PCO2] = 0.22 [PH2 / (PCO+ PCO2)].

[0025] As described above, the present inventors have found that maintaining a desired molar ratio of CO / CO2in the feed stream can be advantageous. As such, in some embodiments as described herein, the ratio [PCO / PCO2] of the feed stream is no more than 1. For example, in various embodiments as described herein, the ratio [PCO / PCO2] of the feed stream is no more than 0.9 (e.g., no more than 0.8). In various embodiments, the ratio [PCO / PCO2] of the feed stream is no more than 0.7 (e.g., no more than 0.6). In various embodiments as described herein, the ratio [PCO / PCO2] of the feed stream is at least 0.05, e.g., at least 0.1. In various embodiments as described herein, the ratio [PCO / PCO2] of the feed stream is at least 0.2, e.g., at least 0.3. In various embodiments as described herein, the ratio [PCO / PCO2] of the feed stream is in the range of 0.05-0.9, e.g., 0.05-0.8, or 0.05-0.7, or 0.05-0.6, or 0.1-0.9, or 0.1-0.8, or 0.1-0.7, or 0.1-0.6. For example, in various embodiments, the molar ratio of CO / CO2is in the range of 0.2-0.9, e.g., 0.2-0.8, or 0.2-0.7, or 0.2-0.6, or 0.3-0.9, or 0.3-0.8, or 0.3-0.7, or 0.3-0.6. The present inventors note that maintaining a high concentration of CO2with respect to CO can help to favor the desirable reverse water-gas shift that converts CO2to CO (as compared to the more undesirable forward water-gas shift to convert CO to CO2).

[0026] The present inventors have found that the desired CO / CO2ratio depends on the H2content of the feed stream. As such, the present inventors have found that providing a feed stream with a molar ratio of H2to the sum of amounts of CO and CO2(i.e., the ratio [PH2 / (PCO+ PCO2)]) of no greater than 3 can provide a desirable high C5+selectivity. In501730 23-1472-WO various embodiments as described herein, the ratio [PH2 / (PCO+ PCO2)] of the feed stream is no greater than 2.8, e.g., no greater than 2.6. In various embodiments, the ratio [PH2 / (PCO+ PCO2)] of the feed stream is no greater than 2.4, e.g., no greater than 2.2. But of course significant amounts of hydrogen are necessary for both the reverse water-gas shift and the Fischer-Tropsch processes used here. Accordingly, in various embodiments, the ratio [PH2 / (PCO+ PCO2)] of the feed stream is at least 0.5, e.g., at least 1. In various embodiments, the ratio [PH2 / (PCO+ PCO2)] of the feed stream is at least 1.3, e.g., at least 1.5. For example in various embodiments, the ratio [PH2 / (PCO+ PCO2)] of the feed stream is in the range of 0.5- 2.8, e.g., 1-2.8, or 1.3-2.8, or 1.5-2.8, or 0.5-2.6, or 1-2.6, or 1.3-2.6, or 1.5-2.6. In various embodiments, the ratio [PH2 / (PCO+ PCO2)] of the feed stream is in the range of 0.5-2.4, e.g., 1-2.4, or 1.3-2.4, or 1.5-2.4, or 0.5-2.2, or 1-2.2, or 1.3-2.2, or 1.5-2.2.

[0027] The present inventors have determined that controlling the molar ratio of H2to CO in the feed stream can be helpful in providing the proper balance of species in the reaction system. For example, in various embodiments as otherwise described herein, a ratio [PH2 / PCO] of the feed stream is no greater than 35, e.g., no greater than 20. In various embodiments, a ratio [PH2 / PCO] of the feed stream is no greater than 15 , e.g., no greater than 10. In various embodiments, a ratio [PH2 / PCO] of the feed stream is no greater than 8, e.g., no greater than 6. Of course, as noted above some hydrogen is necessary; accordingly, in various embodiments, a ratio [PH2 / PCO] of the feed stream is at least 2, e.g., at least 2.5. In various embodiments, a ratio [PH2 / PCO] of the feed stream is at least 3, e.g., at least 3.5. In various embodiments, a ratio [PH2 / PCO] of the feed stream is at least 4, e.g., at least 5. For example, in various embodiments, a ratio [PH2 / PCO] of the feed stream is in the range of 2-35, e.g., 2.5-35, or 3-35, or 3.5-35, or 4-35, or 5-35, or 2-20, or 2.5-20, or 3-20, or 3.5-20, or 4-20, or 5-20. In various embodiments, a ratio [PH2 / PCO] of the feed stream is in the range of 2-15, e.g., 2.5-15, or 3-15, or 3.5-15, or 4-15, or 5-15, or 2-10, or 2.5-10, or 3- 10, or 3.5-10, or 4-10, or 5-10. In various embodiments, a ratio [PH2 / PCO] of the feed stream is in the range of 2-8, e.g., 2.5-8, or 3-8, or 3.5-8, or 4-8, or 5-8, or 2-6, or 2.5-6, or 3-6, or 3.5-6, or 4-6.

[0028] In some embodiments of the disclosure as otherwise described herein, the feed stream further comprises one or more inerts. The person of ordinary skill in the art will appreciate that inerts are gaseous materials that are substantially inert to the reaction conditions, even though they may themselves be reaction products. Examples include nitrogen, C2-C4hydrocarbons and / or methane. For example, it can be desirable to perform the iron FT reaction step in the presence of a significant amount of inerts; the person of ordinary skill in the art can determine a desirable inert content based on the present disclosure For example, in various embodiments, the feed stream further comprises one or501730 23-1472-WO more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure up to 90% of a total pressure of the feed stream, e.g., up to 80%, or up to 70%, or up to 60%, or up to 50% of a total pressure of the feed stream. In various embodiments, the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure in the range of 10-90% of a total pressure of the feed stream, e.g., 10- 80%, 10-70%, 10-60%, or 10-50% of a total pressure of the feed stream. In various embodiments, the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure in the range of 20-90% of a total pressure of the feed stream, e.g., 20-80%, 20-70%, 20-60%, or 20-50% of a total pressure of the feed stream. In various embodiments, the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure in the range of 40-90% of a total pressure of the feed stream, e.g., 40-80%, 40-70%, or 40-60% of a total pressure of the feed stream.

[0029] 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.

[0030] As described above, the process described herein can provide reasonably high conversion of CO2. As used herein, a “conversion” is a net molar fraction of a relevant component of the feed that is converted to other species (be it to desirable products or undesirable species). For example, a CO2conversion is the net fraction of CO2in the feed that is provided as other products in the products stream. Any CO conversion to CO2acts as a negative conversion of CO2, such that conversion can most simply be calculated by subtracting a ratio of CO2in the feed to CO2in the product stream from 1. In various embodiments of the present disclosure as described herein, contacting of the feed stream with the iron-based FT catalyst is conducted at a CO2conversion in the range of 10-60%, e.g., 10-55%, or 10-50%, or 10-45%, or 10-40%, or 20-60%, or 20-55%, or 20-50%, or 20- 45%, or 20-40%, or 25-60%, or 25-55%, or 25-50%, or 25-45%, or 25-40%, or 30-60%, or 30-55%, or 30-50%, or 30-45%. The person of ordinary skill in the art will, based on the disclosure herein, operate at a degree of conversion that provides a desirable product distribution. In some cases, a lower overall conversion may be more favorable; unconverted CO2can be recycled to the feed.

[0031] Notably, the present inventors have determined that the iron FT catalyst materials, under the conditions described herein, can provide desirably high C5+selectivities.501730 23-1472-WO The Fischer-Tropsch process is typically used to make C5+hydrocarbons, for example, unsubstituted C5+hydrocarbons (e.g., alkanes and alkenes) and / or oxygenated C5+hydrocarbons (e.g., C5+alcohols, aldehydes, ketones, carboxylic acids). For example, in various embodiments as described herein, the contacting of the feed stream with the iron- based FT catalyst material is conducted with a C5+selectivity (i.e., for all C5+species) of at least 30%, e.g., at least 40%, or at least 60%. For example, in various embodiments, the contacting of the feed stream with the iron-based FT catalyst material is conducted with a C5+selectivity in the range of 30-75%, or 30-70%, or 30-65%, or 30-60%, or 40-75%, or 40- 70%, or 40-65%, or 40-60%, or 50-75%, or 50-70%, or 50-65%, or 50-60%.

[0032] Iron FT processes also typically make some amount of smaller hydrocarbon products, although these are typically less desirable. The present inventors have found that by controlling the amount of hydrogen in the feed stream as described herein, the relative amount of such smaller hydrocarbon products can be reduced to acceptable levels. In various embodiments, the contacting of the iron-based FT catalyst material with the feed stream is conducted at a C2-4selectivity of no more than 30%, e.g., no more than 25%, or no more than 20%, for example, in the range of 10-30%, or 10-25%, or 10-20%, or 15-30%, or 15-25%, or 15-20%. In various embodiments, the contacting of the iron-based FT catalyst material with the feed stream is conducted with a methane selectivity of no more than 20%, e.g., no more than 20%, e.g., no more than 15%, or no more than 10%, for example, in the range of 3-20%, or 3-15%, or 3-10%, or 5-20%, or 5-15%, or 5-10%.

[0033] In some embodiments as described herein, the iron-based FT catalyst materials under the conditions described herein may have some selectivity for CO. That is, the reverse water-gas shift of CO2may generate some CO that is not immediately reacted in the FT reaction. However, it is desirable to maintain this value relatively low. In various embodiments as disclosure as described herein, the contacting of the feed stream with the iron-based FT catalyst material is conducted with an overall CO selectivity of no more than 50%, e.g., no more than 40%, or no more than 30%, e.g., in the range of 10-50%, or 10- 40%, or 10-30%, or 15-50%, or 15-40%, or 15-30%, or 20-50%, or 20-40%, or 20-30%.

[0034] A variety of iron FT catalysts are known in the art, and iron FT catalysts continue to be developed. The person of ordinary skill in the art, based on the disclosure herein, can select desirable catalysts for use in practicing the methods described herein. As the person of ordinary skill in the art will appreciate, such catalysts can be provided in a variety of physical and chemical forms. Catalysts are often provided in oxidic form for shipping and storage, and are activated by reduction and carbidization in the FT reactor to provide the active carbide that is understood to catalyze the Fischer-Tropsch synthesis. The reduction and / or carbidization can be performed in a separate process step before introducing the feed501730 23-1472-WO stream, or rather can be performed using components of the feed stream itself. Thus, the iron-based FT catalyst is typically in a carbided form when it is contacted with the feed stream to provide C5+products.

[0035] 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.

[0036] As described above, iron-based FT catalyst materials often have both rWGS and FT activity, and as such, the iron-based FT catalyst material is not particularly limited. For example, in some embodiments as described herein, the iron-based FT catalyst material includes at least 10 wt% iron (e.g., at least 20 wt%, or at least 30 wt%, or at least 40 wt% iron), on an elemental basis, exclusive of carbon. In various embodiments as described herein, the iron-based FT catalyst material includes at least 50 wt%, e.g., at least 60 wt%, or at least 70 wt% iron, on an elemental basis, exclusive of carbon.

[0037] 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 -- as the various components of the feed stream are selected to favor the reverse water-gas shift, 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 iron-based FT catalyst comprises at least 0.5 wt% alkali metal, e.g., at least 1 wt% alkali metal, on an elemental basis exclusive of carbon. For example, in various embodiments, the iron-based FT catalyst comprises in the range of 0.5-5 wt% alkali metal, e.g., 0.5-3 wt%, or 0.5-2 wt%, on an elemental basis exclusive of carbon. In various embodiments, the iron-based FT catalyst comprises in the range of 1-5 wt% alkali metal, e.g., in the range of 1-4 wt%, or 1-3 wt%, or 1-2.5 wt%, on an elemental basis exclusive of carbon.

[0038] 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 embodiments501730 23-1472-WO as described herein, the alkali metal is sodium. In particularly desirable embodiments, the alkali metal is potassium.

[0039] The iron-based FT catalyst materials suitable for use in the process as described herein can be a variety of forms and are not particularly limited. For example, the iron-based FT catalyst material may be a supported or unsupported catalyst material. While the form of the catalyst material is not particularly limited, in various desirable embodiments, the iron- based FT catalyst material is a supported catalyst material, wherein the support comprises at least one of titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, silicon oxide and zinc oxide. For example, in various embodiments, the support comprises at least one or aluminum oxide and silicon oxide.

[0040] The person of ordinary skill in the art will appreciate that the iron-based FT catalyst materials of the disclosure can be provided in many forms, depending especially on the particular form of the reactor system in which they are to be used, e.g., in a fixed bed or as a fluidized bed. The supports of the iron-based FT catalyst materials 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 catalyst material for the particular reactor system.

[0041] 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 catalyst material is activated by contact with H2and oxides of carbon (e.g., CO and CO2).

[0042] 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 understand501730 23-1472-WO 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 (Fe0).

[0043] In various embodiments, the treatment with the reducing gas stream is performed in the substantial absence of carbon monoxide. For example, in various embodiments, the reducing gas stream comprises no more than 1 vol% carbon monoxide, e.g., no more than 0.5 vol%, or no more than 0.1 vol%, or no more than 0.05 vol%, or no more than 0.01 vol% carbon monoxide. In some embodiments as described herein, the reducing gas stream further comprises an inert gas. For example, in some embodiments, the inert gas is nitrogen. In some embodiments as described herein, the hydrogen and inert gas are present in the reducing gas stream in a ratio of at least 1:1.

[0044] In various embodiments, treating the iron-based FT catalyst material with the reducing gas stream is conducted at a temperature in the range of 350-650 °C. For example, in various embodiments as described herein, treating the iron-based FT catalyst material with the reducing gas stream is conducted at a temperature in the range of 350-600 °C, or 350-550 °C, or 350-500 °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 375-650 °C, or 375-600 °C, or 375-550 °C, or 375-500 °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.

[0045] 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.

[0046] 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 is501730 23-1472-WO 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.

[0047] 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.

[0048] As noted above, the iron-based FT catalyst material will typically be in the form of a carbided Fischer-Tropsch catalyst material when it is contacted with the feed stream to provide C5+products. 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 a carbide 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 Mössbauer spectroscopy, and as such is expressed as an atomic fraction of iron in the form of carbide of the total iron species visible to Mössbauer spectroscopy.

[0049] 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 the501730 23-1472-WO 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 Mössbauer spectroscopy, and as such is expressed as an atomic fraction of iron in the form of oxide of the total iron species visible to Mössbauer 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.

[0050] 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 Mössbauer spectroscopy.

[0051] 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 CO stream 225 is separated from the iron FT feed stream 211 and contacted with the iron FT catalyst material 213 to activate it. 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.

[0052] As described above, the present inventors have found that to increase overall CO2conversion, maintaining a desired CO / CO2ratio can be advantageous. To maintain this ratio, at least a portion of the CO of the product stream can be recycled to the feed stream. For example, in some embodiments as described herein, the process can include recycling at least a portion (e.g., at least 5 mol%, at least 10 mol%, or at least 25 mol%) of the CO of501730 23-1472-WO the product stream to the feed stream. A schematic of such a process is shown in FIG.2. In the process 200 of FIG.2, a feed stream 211 comprising hydrogen, carbon monoxide, and carbon dioxide is provided to a reaction zone 210 and contacted with an iron-based FT catalyst material 213 under conditions sufficient to form a product stream 212 comprising C5+hydrocarbons and carbon monoxide. Here, the process 200 includes separating from the product stream 212 at least a portion of CO (stream 215a) to recycle to the feed stream 211.

[0053] The amount of CO recycled back to the feed steam can be tailored to maintain the desired [PCO / PCO2] and [PH2 / (PCO+ PCO2)] ratios as described herein. For example, in some embodiments, when the product stream comprises large amounts of CO and CO2, the amount of hydrogen in the feed stream can be adapted to provide desirable [PH2 / (PCO+ PCO2)] ratios. And in the unlikely event that so much CO would be present in the product stream to upset the [PCO / PCO2] ratio upon recycle, additional CO2 can be added into the feed stream.

[0054] The person of ordinary skill in the art would appreciate that, based on the processes as described herein, the product stream may include H2, CO, and CO2and other components in various amounts. Components of the product stream(s) may be separated and used for various purposes in the process described herein.

[0055] For example, in various embodiments of the present disclosure as described herein, the process further comprises separating the product stream to recycle at least a portion (e.g., at least 5 mol%, at least 10 mol%, or at least 25 mol%) of one or more components of the product stream to the feed stream. Since CO2is the primary carbon source for the processes described herein, it can be especially desirable to recycle CO2to the first feed stream. For example, when the product stream(s) includes CO2, the process can include recycling at least a portion (e.g., at least 5 mol%, at least 10 mol%, or at least 25 mol%) of the CO2of the product stream(s) to the feed stream(s). The product stream(s) may also include H2; in some embodiments, the process further includes recycling at least a portion of H2of the product stream(s) (e.g., at least 5 mol%, at least 10 mol%, or at least 25 mol%) to the feed stream(s). It is typically convenient to recycle these gaseous components of the product stream together.

[0056] Such recycling is shown in the process 200 of FIG.2. Here, the process 200 includes separating from the product stream 212 at least a portion of CO2(stream 215b) to recycle to the feed stream 211. Similarly, the process 200 includes separating from the product stream 212 at least a portion of H2(stream 214) to recycle to the feed stream 211. While streams 215a / b is depicted as entering reactors 210 through a different inlet than the501730 23-1472-WO rest of the feed stream 211, it is considered to be part of the feed stream(s), as it is part of the material input to the process step.

[0057] The product stream comprises C5+hydrocarbons and carbon monoxide. In some embodiments as described herein, the product stream further comprises water. In some embodiments, the process further comprises separating the product stream to provide a water-rich iron FT product stream and a water-poor iron FT product. An example of such a process is shown schematically in FIG.3. In FIG.3, the process 300 includes process for preparing hydrocarbons by providing an feed stream 311 comprising hydrogen, carbon monoxide and carbon dioxide, here, to an iron FT reaction zone, e.g., a reactor 310. An iron-based FT catalyst 313, as described herein, is contacted with the feed stream 311 under conditions sufficient to form a product stream 312 comprising C5+hydrocarbons and carbon monoxide. The product stream 312 is then separating in a water separation zone 316 to provide a water rich product stream 317A and a water-poor product stream lean 317B. 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 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; 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 condense water; in such cases, C5+products will also be knocked out, and can be separated from water by a variety of methods known in the art. However, use of a knockout vessel can in some cases cool the iron FT product stream enough so that it is desirably reheated for introduction to the cobalt FT process step.

[0058] As described above, the product stream(s) also include C5+hydrocarbons. As would be understood by the person of ordinary skill in the art, the C5+hydrocarbons and any water present in the product stream can be conveniently condensed. In some embodiments of the process as described herein, these substances can be separated from the product stream via condensation. For example, in some embodiments as described herein, the process further comprises separating the product stream to provide a condensate-rich iron FT product stream enriched in water and C5+hydrocarbons and a condensate-poor product stream lean in water and C5+hydrocarbons. An example of such a process is shown schematically in FIG.4. In FIG.4, the process 400 includes process for preparing hydrocarbons by providing an feed stream 411 comprising hydrogen, carbon monoxide, and carbon dioxide, here, to an iron FT reaction zone, e.g., a reactor 410. An iron-based FT catalyst 413, as described herein, is contacted with the iron FT feed stream 411 under conditions sufficient to form an product stream 412 comprising C5+hydrocarbons and carbonmonoxide. The product stream 412 is then separating in a condensate separation zone 416 to provide a condensate-rich product stream enriched in water and C5+hydrocarbons 417A and a condensate-poor product stream lean in water and C5+hydrocarbons 417B. In some embodiments as described herein, the process further comprises recovering C5+hydrocarbons from the condensate-rich stream(s). An example of such a process is shown in FIG.4. In the process 400 for FIG.4, the condensate-rich product stream 417A is provided to a hydrocarbon recovery zone 450 to provide a C5+hydrocarbon stream 452.

[0059] As with the product stream, the components of the water-poor and / or condensate-poor product stream, e.g., hydrogen, carbon monoxide, and carbon dioxide may be used in other feeds of the process as described herein. As such, in some embodiments as described herein, at least a portion of hydrogen, carbon monoxide and carbon dioxide of the water-poor and / or condensate-poor product stream is included in the feed stream. For example, in the process of FIG.3, at least a portion of H2of the water-poor product stream 317B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 311via recycle stream 336. In the process of FIG.4, at least a portion of H2of the condensate-poor product stream 417B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 411 via recycle stream 436.

[0060] Similarly, it can be desirable to recycle CO of the water-poor product stream(s), for example, to the feed stream. For example, in the process of FIG.3, at least a portion of carbon monoxide of the water-poor product stream 317B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 311 via recycle stream 336. In the process of FIG.4, at least a portion of carbon monoxide of the condensate-poor product stream 417B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 411 via recycle stream 436.

[0061] As with hydrogen and carbon monoxide, it can be desirable to recycle carbon dioxide of the water-poor and / or condensate-poor product stream to the feed stream. For example, in the process of FIG.3, at least a portion of carbon dioxide of the water-poor product stream 317B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 311 via recycle stream 336. In the process of FIG.4, at least a portion of carbon dioxide of the condensate-poor product stream 417B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 411 via recycle stream 436.

[0062] Moreover, when one or more inerts are used in the process steps, it can be desirable to recycle these. For example, in various embodiments, the process includes recycling at least a portion of inerts of the water-poor and / or condensate-poor productstream to the feed stream. For example, in the process of FIG.3, at least a portion of inerts of the water-poor product streams 317A (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 311 via recycle stream 336. In the process of FIG.4, at least a portion of inerts of the condensate-poor product stream 417B (e.g., at least 25%, at least 50%, at least 75%, or at least 90%) can be recycled to the feed stream 411 via recycle stream 436. In various embodiments, a purge stream can be incorporated with the recycle stream to prevent uncontrolled accumulation of inerts in the recycle stream (not shown here).

[0063] As described above, the water-poor and condensate-poor product streams comprise carbon dioxide, carbon monoxide, and hydrogen. In some embodiments as described herein, the water-poor and / or condensate-poor product stream may further include C1-C4hydrocarbons.

[0064] The C1-C4hydrocarbons, e.g., light hydrocarbons, while often not a desired portion of a Fischer-Tropsch product to be used as a fuel or a lubricant, can themselves be useful for a number of purposes. Accordingly, in various embodiments, the process further includes separating at least a portion of C1-C4hydrocarbons of the water-poor and / or condensate poor product streams to provide a light hydrocarbon stream. For example, in the process 300 of FIG.3, at least a portion of the C1-C4hydrocarbon is separated from the water-poor product stream 317B to provide a light hydrocarbon stream 338. The light hydrocarbon stream can, for example, be recycled to the feed streams. In the process 300 of FIG.3, light hydrocarbons 338 can be provided as part of the recycle stream 336, which becomes part of the feed stream 311. Similarly, in the process 400 of FIG.4, at least a portion of the C1-C4hydrocarbon is separated from the condensate-poor product stream 417B to provide a light hydrocarbon stream 438. The light hydrocarbon stream can, for example, be recycled to the feed streams. In the process 400 of FIG.4, light hydrocarbons 438 can be provided as part of the recycle stream 436, which becomes part of the feed stream 411.

[0065] There are other uses for the light hydrocarbon stream. For example, in some embodiments, the process further comprises at least partially oxidizing at least a portion of the light product stream in a partial oxidation reaction zone to provide a partial oxidation (pOX) stream comprising carbon monoxide e.g., a CO- and / or CO2-containing partial oxidation (pOX) stream, and including at least a portion of the pOX stream in the feed streams. An example of such a process is shown schematically in FIG.5, in which the process 500, the feed stream 511, the product stream 512, the iron FT catalyst material 513, the water-rich / condensate-rich product stream 517A, the water-poor / condensate-poor product stream 517B, and recycle stream 536 can be as otherwise described herein. Here,501730 23-1472-WO the process includes oxidizing at least a portion of the light hydrocarbon stream 538 in a partial oxidation reaction zone 592 to provide a CO- and / or CO2containing pOX stream, and including at least a portion of the pOX stream 594 stream in the first feed stream 511.

[0066] Similarly, in some embodiments as described herein, the process further includes oxidizing at least a portion of light product stream in an oxidation reaction zone to provide a oxidation (OX) product stream comprising carbon dioxide, and including at least a portion of the carbon dioxide of the oxidation product stream to the first feed stream. An example of such a process is shown in FIG.6, where the process 600 includes oxidizing at least a portion of the light hydrocarbon stream 638 in an oxidation reaction zone 692 to provide a CO2containing OX stream, and including at least a portion of the OX stream 694 stream in the first feed stream 611a. The process 600, the feed stream 611, the product stream 612, the iron FT catalyst material 613, the water-rich / condensate-rich product stream 617A, the water-poor / condensate-poor product stream 617B, and recycle stream 636 can be as otherwise described herein.

[0067] Moreover, the light hydrocarbon stream can be burned to provide heat energy, which can be used to heat various process streams, or to generate electricity. Accordingly, in various embodiments, the process includes burning at least a portion of the light hydrocarbon stream to provide energy, e.g., heat energy or electrical energy. For example, in the process 500 of FIG.5, a portion of light hydrocarbon stream 538 is burned in a power generation zone (here, in an electrical generator 570), to generate electricity stream 572. In various embodiments, the heat energy may be used to provide the needed heat duty for the process. For example, in the process 500 of FIG.5, a portion of the light hydrocarbon stream 538 is burned in a power generation zone (here, in a heat generator 580), to generate heat stream 582. The heat stream 582 is conducted to a heat exchange zone 590 to heat the feed stream 511.

[0068] The present inventors have noted that it can be desirable to provide for heat exchange with a relatively hot feed stream to cool the product stream to provide heat elsewhere to the integrated process. For example, in various embodiments of the processes as otherwise described herein, the process further comprises exchanging heat between at least a portion of the product stream and at least a portion of the feed stream, thereby cooling at least a portion of the first product stream and heating at least a portion of the first feed stream. An example of such a process is shown schematically in FIG.6. In FIG.6, the process 600 includes exchanging heat between at least a portion of the product stream 612 and a least a portion of the feed stream 611 in a heat exchange zone 630, thereby cooling at least a portion of the product stream 612 and heating at least a portion of the feed stream501730 23-1472-WO 611. The person of ordinary skill in the art will appreciate that a wide variety of heat exchangers can be used for this purpose.

[0069] Of course, any excess heat in the product stream can be additionally or alternatively used for other purposes. For example, in various embodiments the process further comprises exchanging heat between at least a portion of first product stream and a steam generation zone, thereby cooling at least a portion of the product stream and providing heat to the steam generation zone. This is shown in FIG.6. Here, after heat exchange with the feed stream 611, the product stream 612 is conducted to steam generation zone 632, to cool the product stream 612 and provide heat to the steam generation zone 632. Steam can be generated from the heat provided, and electricity can be generated from the steam. For example, in the embodiment of FIG.6, electricity stream 664 is provided by the generation of electricity using steam generated in the steam generation zone 632. Of course, as would be understood to the person of ordinary skill in the art, the steam generated in the steam generation zone may be used in other processes. In various embodiments, the steam may be used to heat the first feed stream. For example, in the embodiment of FIG.6, the steam stream 666 generated in the steam generation zone 632 is conducted to the heat exchange zone 690 to the feed stream 611.

[0070] As noted above, the process described herein provides product streams that includes C5+hydrocarbons (e.g., unsubstituted hydrocarbons like alkanes and alkenes, and / or oxygenated hydrocarbons such as alcohols). Accordingly, in various embodiments, one or more products are provided from at least a portion of C5+hydrocarbons of the product streams. The C5+hydrocarbons can be used as the basis of a variety of fuels, e.g., gasoline, diesel, aviation fuel. Other products, like waxes and lubricants, can also be made. And alkenes and oxygenates can be used as feedstocks in a variety of other processes.

[0071] The person of ordinary skill in the art will use conventional post-processing techniques to convert the C5+hydrocarbon-containing product to desirable products such as desirable fuels. For example, in various embodiments, the process further includes hydroprocessing at least a portion of C5+hydrocarbons of the product streams. 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 material. A wide variety of hydroprocessing techniques are known and the person of ordinary skill in the art will apply them here. For example, in the process 500 of FIG.5, water-rich / condensate-rich product stream 517A is hydroprocessed in hydroprocessing reactors 550, to provide hydroprocessed product streams 552.501730 23-1472-WO

[0072] The processes described herein can be operated in a wide variety of reactor systems. The reactors used for the process of the present disclosure as described herein are not particularly limited, and the person of ordinary skill in the art will be able to select an appropriate reactor. In various embodiments, the process is performed in a reactor system comprising one or more iron FT catalyst containers in which the iron FT catalyst is disposed. These can be provided in the same reactor.

[0073] As described above, CO2and H2are substantial inputs to the process as described herein. Advantageously, the present inventors have recognized that each of these can come from renewable or otherwise environmentally responsible sources.

[0074] CO2can be captured from the environment generally 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 of the disclosure as described herein, at least a part of the CO2of the first feed stream, the second feed stream, and / or subsequent feed streams 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 first feed stream, the second feed stream, and / or the subsequent feed streams 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 first feed stream, the second feed stream, and / or the subsequent feed streams is from a manufacturing plant such as a bioethanol plant (e.g., CO2produced fermentation), a steel plant, or a cement plant. Accordingly, the processes of the disclosure as described herein can be not only carbon neutral, but in some cases a net consumer of carbon dioxide. These benefits in particular make the integrated processes highly attractive for decarbonizing transportation fuels, for both automotive and aviation sectors.

[0075] Similarly, H2can be provided from environmentally-responsible sources. In some embodiments, at least a part of the H2of the first feed stream, the second feed stream, and / or the subsequent feed streams 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 first feed stream, the second feed stream, and / or the subsequent feed streams 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 first feed stream, the second feed stream, and / or the subsequent feed streams 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 some501730 23-1472-WO embodiments, at least part (e.g., at least 25%, at least 50%, or at least 75%) of the H2of the first feed stream, the second feed stream, and / or the subsequent feed streams is grey hydrogen, black hydrogen, brown hydrogen, pink hydrogen, turquoise hydrogen, yellow hydrogen, and / or white hydrogen.

[0076] The present inventors have noted that electrolysis of water is a desirable way to provide hydrogen to the claimed processes. Accordingly, in some embodiments, the process includes providing at least a portion of H2to the first feed stream, the second feed stream, and / or the subsequent feed stream by electrolysis of water. In some embodiments, the electrolysis of water is performed using at least partially electricity from a renewable source, e.g., to provide so-called “green hydrogen.” However, the present inventors have noted that electricity can be generated as part of the claimed process, e.g., using heat exchange from the product stream, or by burning light hydrocarbons as described above. In some embodiments, the electrolysis of water is performed using at least partially electricity generated according to the processes as described herein. For example, in the process 600 of FIG.6, the water-rich product stream 617A separated from the product stream is electrolyzed in electrolyzer 660, using electricity 664 generated from steam made in the steam generation zone 632 by heat exchange from first product stream. H2generated in the electrolysis is provided via stream 665 to the feed stream. In some embodiments, at least a portion of O2generated in the electrolysis 663 is provided to a partial oxidation reaction zone or oxidation reaction zone as described herein. EXAMPLES

[0077] The Examples that follow are illustrative of specific embodiments of the process of the disclosure, and various uses thereof. They are set forth for explanatory purposes only, and are not to be taken as limiting the scope of the disclosure.

[0078] Example 1.

[0079] To determine CO / CO2ratios that provide desirable high C5+selectivity, and their dependence of H2content in the feed stream, five different iron-based catalyst materials were contacted with a feed stream including hydrogen, carbon monoxide, carbon dioxide, and inerts, using a high-throughput 16-fold parallel test rig. The rig is equipped with individual temperature control per reactor tube. Each reactor outlet has a hot pot wax collection system operated at ~160 °C, with remaining gases / vapors being fed to an online GC capable of detecting both light gases and hydrocarbons up to a carbon number of ~15. The feed stream included approximately 17% carbon dioxide. Five different carbon monoxide concentrations were used (0%, 0.89%, 2.66%, 8.4%, and 16.64%) in the feed stream. The hydrogen concentration was not adjusted, and the co-fed CO replaced inert501730 23-1472-WO gas in the feed. As such, the H2 / (CO+CO2) ratio decreased from 2.0 to 1.0 upon addition. For each run, the catalyst was contacted with the feed stream at a temperature of 330 °C and a pressure of 40.3 bar. Table 1 recites the conditions these tests were conducted at.

[0080] Table 1. Run H2% in CO% in CO2% Catalyst H2 / CO H2 / CO2CO / CO2H2 / (CO+CO2) No. feed feed in feed 1 33.53 0 16.78 - 2.00 0.00 2.00 2 33.26 0.89 16.85 37.37 1.97 0.05 1.87 Na / Fe on 3 33.26 2.66 16.85 12.50 1.97 0.16 1.70 alumina 4 36.6 8.4 16.0 4.4 2.3 0.53 1.5 5 33.26 16.63 16.85 2.00 1.97 0.99 0.99 6 33.53 0 16.78 - 2.00 0.00 2.00 7 33.26 0.89 16.85 37.37 1.97 0.05 1.87 8 Fe-Mn-K 33.26 2.66 16.85 12.50 1.97 0.16 1.70 9 36.63 8.42 16.00 4.35 2.29 0.53 1.50 10 33.26 16.63 16.85 2.00 1.97 0.99 0.99 11 33.53 0 16.78 - 2.00 0.00 2.00 12 Fe / ZnO 33.26 0.89 16.85 37.37 1.97 0.05 1.87 13 with ~2 33.26 2.66 16.85 12.50 1.97 0.16 1.70 14 wt% Na 36.63 8.42 16.00 4.35 2.29 0.53 1.50 15 33.26 16.63 16.85 2.00 1.97 0.99 0.99 16 33.53 0 16.78 - 2.00 0.00 2.00 17 Fe / ZnO 33.26 0.89 16.85 37.37 1.97 0.05 1.87 18 with ~2 33.26 2.66 16.85 12.50 1.97 0.16 1.70 19 wt% Na 36.63 8.42 16.00 4.35 2.29 0.53 1.50 20 33.26 16.63 16.85 2.00 1.97 0.99 0.99 21 33.53 0 16.78 - 2.00 0.00 2.00 22 Fe / ZnO 33.26 0.89 16.85 37.37 1.97 0.05 1.87 23 with ~2 33.26 2.66 16.85 12.50 1.97 0.16 1.70 24 wt% Na 36.63 8.42 16.00 4.35 2.29 0.53 1.50 25 33.26 16.63 16.85 2.00 1.97 0.99 0.99501730 23-1472-WO

[0081] The resulting components of the product stream are shown in Table 2 and the C5+selectivity vs the %CO percent for each of the five catalyst contacts with the feed stream are shown in FIG.7.

[0082] Table 2. C5- C8- CH4C2-C4incl C2-C4C5+(incl C5+C5+(incl all Run C2-C4C10C16w oxygenates hydrocarbons oxygenates) oxygenates) C11+No. oxygenates w w CO2w CO only w CO w CO CO CO 1 7.5 32 27 4 - - 62 67 38 2 8.5 37 32 5 - - 55 60 28 3 8.1 35 31 5 29 13 57 61 30 4 7.5 33 29 4 30 15 60 63 30 5 5.0 23 21 2 23 13 48 50 25 6 9.8 35 30 5 - - 54 59 34 7 11.1 41 36 5 - - 46 52 21 8 9.9 38 33 5 24 8 52 57 29 9 9.2 38 33 5 27 11 53 58 26 10 5.3 26 23 3 22 11 44 47 22 11 8.5 33 28 5 - - 58 63 39 12 10.1 41 35 6 - - 48 54 23 13 8.7 35 30 5 24 10 56 61 34 14 8.8 37 32 5 28 14 55 59 26 15 5.2 24 21 3 21 12 47 49 25 16 7.3 30 26 4 - - 61 65 38 17 7.8 34 29 4 - - 58 62 32 18 7.7 33 29 4 28 13 60 64 32 19 7.4 32 28 3 29 16 61 64 32 20 5.0 22 20 2 20 12 47 49 27 21 8.1 32 27 5 - - 57 62 35 22 9.1 37 31 6 - - 52 57 26 23 8.5 36 31 5 27 12 56 61 31 24 7.9 34 29 4 28 15 59 63 31 25 5.2 23 21 2 21 12 42 45 21501730 23-1472-WO

[0083] From Table 2 and FIG.7, it can be seen that while C5+selectivity initially decreases with small amounts of carbon monoxide present, the selectivity increases once an intermediate ratio of CO / CO2is reached, before decreasing again.

[0084] Example 2.

[0085] To determine CO / CO2ratios that provide desirable high C5+selectivity and their dependence on H2content in the feed stream, five different iron-based catalyst were contacted with a feed stream including hydrogen, carbon monoxide, carbon dioxide, and inerts. The feed stream included approximately 17% carbon dioxide. Four different carbon monoxide concentrations were used (0%, 0.9%, 2.7%, and 8.9%,) in the feed stream. The hydrogen concentration was adjusted to maintain a H2 / (CO+CO2) ratio of 2.0 upon CO addition. For each run, the catalyst was contacted with the feed stream at a temperature of 330 °C and a pressure of 40.3 bar. Table 3 recites the conditions these tests were conducted at.501730 23-1472-WO

[0086] Table 3. Run H2% in CO% in CO2% in H2 / H2 / CO / H2 / Catalyst No. feed feed feed CO CO2CO2(CO+CO2) 26 34 0.0 16.8 - 2.0 0.00 2.0 27 Na / Fe on 35.0 0.9 16.9 39.4 2.1 0.05 2.0 28 alumina 38.6 2.7 16.9 14.5 2.3 0.16 2.0 29 51.0 8.9 16.9 5.7 3.0 0.53 2.0 30 33.5 0.0 16.8 - 2.0 0.00 2.0 31 35.0 0.9 16.9 39.4 2.1 0.05 2.0 Fe-Mn-K 32 38.6 2.7 16.9 14.5 2.3 0.16 2.0 33 51.0 8.9 16.9 5.7 3.0 0.53 2.0 34 33.5 0.0 16.8 - 2.0 0.00 2.0 35 Fe / ZnO with 35.0 0.9 16.9 39.4 2.1 0.05 2.0 36 ~2 wt% Na 38.6 2.7 16.9 14.5 2.3 0.16 2.0 37 51.0 8.9 16.9 5.7 3.0 0.53 2.0 38 33.5 0.0 16.8 - 2.0 0.00 2.0 39 Fe / ZnO with 35.0 0.9 16.9 39.4 2.1 0.05 2.0 40 ~2 wt% Na 38.6 2.7 16.9 14.5 2.3 0.16 2.0 41 51.0 8.9 16.9 5.7 3.0 0.53 2.0 42 33.5 0.0 16.8 - 2.0 0.00 2.0 43 Fe / ZnO with 35.0 0.9 16.9 39.4 2.1 0.05 2.0 44 ~2 wt% Na 38.6 2.7 16.9 14.5 2.3 0.16 2.0 45 51.0 8.9 16.9 5.7 3.0 0.53 2.0

[0087] The resulting components of the product stream are shown in Table 4 and the C5+ selectivity vs the %CO percent for each of the five catalyst contacts with the feed stream are shown in FIG.8.501730 23-1472-WO

[0088] Table 4. CH4C2-C4incl C2-C4C5- C8- C5+(incl C5+C5+(incl all Run C2-C4w oxygenates hydrocarbons C10w C16w oxygenates) oxygenates) C11+No. oxygenates CO2w CO only CO CO w CO w CO 26 8 32 27 4 - - 62 67 38 27 9 37 31 6 29 13 54 60 25 28 8 34 29 5 27 12 59 63 31 29 8 37 32 5 32 15 55 60 23 30 10 35 30 5 - - 54 59 34 31 12 42 36 6 24 8 45 51 20 32 10 37 32 5 22 7 53 58 31 33 12 44 38 6 28 10 44 50 17 34 9 33 28 5 - - 58 63 39 35 10 38 32 6 24 9 52 58 28 36 9 36 31 5 24 10 55 60 31 37 11 42 36 6 29 13 48 54 18 38 7 30 26 4 - - 61 65 38 39 8 33 29 4 26 11 58 62 33 40 8 33 29 4 27 12 59 63 32 41 9 36 31 4 31 14 56 60 25 42 8 32 27 5 - - 57 62 35 43 9 37 31 6 26 10 51 57 26 44 9 34 29 5 25 11 58 62 33 45 10 40 34 6 30 13 50 56 20

[0089] From Table 4 and FIG.8, it can be seen that while C5+selectivity initially decreases with small amounts of carbon monoxide present, the selectivity increases once an intermediate ratio of CO / CO2is reached, before decreasing again.

[0090] Additionally, from Examples 1 and 2, it can be seen that the same behavior occurs in both scenarios. First a dip in C5+selectivity which recovers to values close to the CO-free reference case, before even higher CO concentrations lead to continuously lower C5+selectivities. It can also be noted that the amount of CO that can be accepted in a H2+CO2 containing feed in order achieve high C5+selectivities for mixed CO+CO2feeds depends on the H2concentration, and at higher H2concentrations the highest C5+selectivity region may be located at lower CO / CO2ratios and in a narrower range. Without being501730 23-1472-WO bound by theory, the present inventors hypothesize that low CO concentrations and low CO / CO2ratios, results in very high H2 / CO ratios, which results in conversion of CO mostly to light hydrocarbons rather than C5+hydrocarbons. CO2conversion is only slightly decreased due to low CO concentrations. When the feed stream includes moderate H2 / CO ratios, this prevents over-hydrogenation of CO while still providing positive (but clearly decreased) CO2conversion. Overall, the selectivity to C5+remains higher in this region compared to very low CO feed percentages. However, if the CO concentration in the feed increases further, the CO2conversion becomes zero, meaning only CO is being converted at temperatures that are “too high” to be in the highest C5+selectivity regime, hence producing lower amounts of product. Upon further increase in the CO concentration, CO2is actively produced (providing a subtractive effect on CO2conversion), which means the C5+selectivity amongst all products (incl. the additional CO2produced) drops further. FIG.9 illustrates these general trends.

[0091] Various aspects of the disclosure are illustrated by the following enumberated embodiments, which may be combined in any number and in any combination not logically or technically inconsistent. Embodiment 1. A process for preparing hydrocarbons, comprising providing a feed stream comprising H2, CO, and CO2; contacting the feed stream with an iron-based FT catalyst under conditions to form a product stream comprising C5+hydrocarbons and CO; and recycling at least a portion of the CO of the product stream to the feed stream; wherein the feed stream has a H2partial pressure expressed in bars (i.e., PH2), a CO2partial pressure expressed in bars (i.e., PCO2), and a CO partial pressure expressed in bars (i.e., PCO) such that a value X as defined by the equation X = -80.9156 + 0.6891[PH2] + 79.6799[PCO2 / (PCO+ PCO2)] + 42.3173[PH2 / (2PCO+ 3PCO2)] is at least 0; on a plot of [PCO / PCO2] vs. [PH2 / (PCO+ PCO2)], the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.16[PH2 / (PCO+ PCO2)]; a ratio of [PCO / PCO2] is no greater than 1; and a ratio of [PH2 / (PCO+ PCO2)] is no greater than 3. Embodiment 2. The process according to embodiment 1, wherein X is at least 1, e.g., at least 2, or at least 5.501730 23-1472-WO Embodiment 3. The process according to embodiment 1, wherein X is at least 10, e.g., at least 15. Embodiment 4. The process according to embodiment 1, wherein X is at least 20, e.g., at least 25 or at least 30. Embodiment 5. The process according to any of embodiments 1-4, wherein X is no more than 60, e.g., no more than 55. Embodiment 6. The process according to any of embodiments 1-4, wherein X is no more than 50, e.g., no more than 45. Embodiment 7. The process according to any of embodiments 1-4, wherein X is no more than 40, e.g., no more than 35. Embodiment 8. The process according to embodiment 1, wherein X is in the range of 1-60, e.g., 1-55, or 1-50, or 1-45, or 1-40, or 1-35. Embodiment 9. The process according to embodiment 1, wherein X is in the range of 2-60, e.g., 2-55, or 2-50, or 2-45, or 2-40, or 2-35. Embodiment 10. The process according to embodiment 1, wherein X is in the range of 5-60, e.g., 5-55, or 5-50, or 5-45, or 5-40, or 5-35. Embodiment 11. The process according to embodiment 1, wherein X is in the range of 10-60, e.g., 10-55, or 10-50, or 10-45, or 10-40, or 10-35. Embodiment 12. The process according to embodiment 1, wherein X is in the range of 20-60, e.g., 20-55, or 20-50, or 20-45, or 20-40, or 20-35. Embodiment 13. The process according to embodiment 1, wherein X is in the range of 25-60, e.g., 25-55, or 25-50, or 25-45, or 25-40, or 25-35. Embodiment 14. The process according to embodiment 1, wherein X is in the range of 30-60, e.g., 30-55, or 30-50, or 30-45, or 30-40.Embodiment 15. The process according to any of embodiments 1-14 wherein the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.17 [PH2 / (PCO+ PCO2)], e.g., above the line [PCO / PCO2] = 0.18 [PH2 / (PCO+ PCO2)]. Embodiment 16. The process according to any of embodiments 1-14, wherein the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.19 [PH2 / (PCO+ PCO2)], e.g., above the line [PCO / PCO2] = 0.20 [PH2 / (PCO+ PCO2)]. Embodiment 17. The process according to any of embodiments 1-14, wherein the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.21 [PH2 / (PCO+ PCO2)], e.g., above the line [PCO / PCO2] = 0.22 [PH2 / (PCO+ PCO2)]. Embodiment 18. The process according to any of embodiments 1-17, wherein the ratio [PCO / PCO2] is no more than 0.9 (e.g., no more than 0.8). Embodiment 19. The process according to any of embodiments 1-17, wherein the ratio [PCO / PCO2] is no more than 0.7 (e.g., no more than 0.6). Embodiment 20. The process according to any of embodiments 1-19, wherein the ratio [PCO / PCO2] is at least 0.05 (e.g., at least 0.1). Embodiment 21. The process according to any of embodiments 1-19, wherein the ratio [PCO / PCO2] is at least 0.2 (e.g., at least 0.3). Embodiment 22. The process according to any of embodiments 1-17, wherein the ratio [PCO / PCO2] is in the range of 0.05-0.9, e.g., 0.05-0.8, or 0.05-0.7, or 0.05-0.6, or 0.1-0.9, or 0.1-0.8, or 0.1-0.7, or 0.1-0.6. Embodiment 23. The process according to any of embodiments 1-17, wherein the ratio [PCO / PCO2] is in the range of 0.2-0.9, e.g., 0.2-0.8, or 0.2-0.7, or 0.2-0.6, or 0.3-0.9, or 0.3-0.8, or 0.3-0.7, or 0.3-0.6. Embodiment 24. The process according to any of embodiments 1-23, wherein the ratio [PH2 / (PCO+ PCO2)] is no greater than 2.8, e.g., no greater than 2.6. Embodiment 25. The process according to any of embodiments 1-23, wherein the ratio [PH2 / (PCO+ PCO2)] is no greater than 2.4, e.g., no greater than 2.2.Embodiment 26. The process according to any of embodiments 1-25, wherein the ratio [PH2 / (PCO+ PCO2)] is at least 0.5, e.g., at least 1. Embodiment 27. The process according to any of embodiments 1-25, wherein the ratio [PH2 / (PCO+ PCO2)] is at least 1.3, e.g., at least 1.5. Embodiment 28. The process according to any of embodiments 1-23, wherein the ratio [PH2 / (PCO+ PCO2)] is in the range of 0.5-2.8, e.g., 1-2.8, or 1.3-2.8, or 1.5-2.8, or 0.5-2.6, or 1- 2.6, or 1.3-2.6, or 1.5-2.6. Embodiment 29. The process according to any of embodiments 1-23, wherein the ratio [PH2 / (PCO+ PCO2)] is in the range of 0.5-2.4, e.g., 1-2.4, or 1.3-2.4, or 1.5-2.4, or 0.5-2.2, or 1- 2.2, or 1.3-2.2, or 1.5-2.2. Embodiment 30. The process according to any of embodiments 1-29, wherein a ratio [PH2 / PCO] of the feed stream is no greater than 35, e.g., no greater than 20. Embodiment 31. The process according to any of embodiments 1-29, wherein a ratio [PH2 / PCO] of the feed stream is no greater than 15 , e.g., no greater than 10. Embodiment 32. The process according to any of embodiments 1-29, wherein a ratio [PH2 / PCO] of the feed stream is no greater than 8, e.g., no greater than 6. Embodiment 33. The process according to any of embodiments 1-32, wherein a ratio [PH2 / PCO] of the feed stream is at least 2, e.g., at least 2.5. Embodiment 34. The process according to any of embodiments 1-32, wherein a ratio [PH2 / PCO] of the feed stream is at least 3, e.g., at least 3.5. Embodiment 35. The process according to any of embodiments 1-32, wherein a ratio [PH2 / PCO] of the feed stream is at least 4, e.g., at least 5. Embodiment 36. The process according to any of embodiments 1-29, wherein a ratio [PH2 / PCO] of the feed stream is in the range of 2-35, e.g., 2.5-35, or 3-35, or 3.5-35, or 4-35, or 5-35, or 2-20, or 2.5-20, or 3-20, or 3.5-20, or 4-20, or 5-20.501730 23-1472-WO Embodiment 37. The process according to any of embodiments 1-29, wherein a ratio [PH2 / PCO] of the feed stream is in the range of 2-15, e.g., 2.5-15, or 3-15, or 3.5-15, or 4-15, or 5-15, or 2-10, or 2.5-10, or 3-10, or 3.5-10, or 4-10, or 5-10. Embodiment 38. The process according to any of embodiments 1-29, wherein a ratio [PH2 / PCO] of the feed stream is in the range of 2-8, e.g., 2.5-8, or 3-8, or 3.5-8, or 4-8, or 5-8, or 2-6, or 2.5-6, or 3-6, or 3.5-6, or 4-6. Embodiment 39. The process according to any of embodiments 1-38, wherein the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure up to 90% of a total pressure of the feed stream, e.g., up to 80%, or up to 70%, or up to 60%, or up to 50% of a total pressure of the feed stream. Embodiment 40. The process according to any of embodiments 1-38, wherein the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure in the range of 10-90% of a total pressure of the feed stream, e.g., 10-80%, 10-70%, 10-60%, or 10-50% of a total pressure of the feed stream. Embodiment 41. The process according to any of embodiments 1-38, wherein the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure in the range of 20-90% of a total pressure of the feed stream, e.g., 20-80%, 20-70%, 20-60%, or 20-50% of a total pressure of the feed stream. Embodiment 42. The process according to any of embodiments 1-38, wherein the feed stream further comprises one or more inerts (e.g., methane, C2-C4hydrocarbons and / or nitrogen), in a partial pressure in the range of 40-90% of a total pressure of the feed stream, e.g., 40-80%, 40-70%, or 40-60% of a total pressure of the feed stream. Embodiment 43. The process according to any of embodiments 1-42, wherein the feed stream has a partial pressure of water content of no more than 10% of a total pressure of the feed stream, e.g., no more than 2%, or no more than 0.5%, of a total pressure of the feed stream. Embodiment 44. The process according to any of embodiments 1-43, wherein the contacting of the feed stream with the iron-based FT catalyst material in the reaction zone is conducted at a temperature in the in the range of 250-400 °C, e.g., 250-375 °C, or 250-350 °C, or 250-325 °C, or 250-300 °C, or 275-400 °C, or 275-375 °C, or 275-350 °C, or 275-325501730 23-1472-WO °C, or 300-400 °C, or 300-375 °C, or 300-350 °C, or 325-375 °C, or 325-350 °C, or 350-400 °C. Embodiment 45. The process according to any of embodiments 1-44, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a total pressure in the range of 5-100 bar. Embodiment 46. The process according to any of embodiments 1-44, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a total pressure in the range of 5-90 bar, e.g., 5-80 bar, or 5-70 bar, or 5-60 bar, or 5-50 bar. Embodiment 47. The process according to any of embodiments 1-44, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a total pressure in the range of 10-100 bar, e.g., 10-90 bar, or 10-80 bar, or 10-70 bar, or 10-60 bar, or 10-50 bar. Embodiment 48. The process according to any of embodiments 1-44, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a total pressure in the range of 15-100 bar, e.g., 15-90 bar, or 15-80 bar, or 15-70 bar, or 15-60 bar, or 15-50 bar. Embodiment 49. The process according to any of embodiments 1-44, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a total pressure in the range of 20-100 bar, e.g., 20-90 bar, or 20-80 bar, or 20-70 bar, or 20-60 bar, or 20-50 bar. Embodiment 50. The process according to any of embodiments 1-49, wherein the contacting of the feed stream with the iron-based FT catalyst material is performed at a GHSV in the range of 200 - 20000 h-1, e.g., 500-20000 h-1, or 200-10000 h-1, or 500-10000 h-1. Embodiment 51. The process according to any of embodiments 1-50, wherein the contacting is conducted with a CO2conversion in the range of 10-60%, e.g., 10-55%, or 10- 50%, or 10-45%, or 10-40%, or 20-60%, or 20-55%, or 20-50%, or 20-45%, or 20-40%, or 25-60%, or 25-55%, or 25-50%, or 25-45%, or 25-40%, or 30-60%, or 30-55%, or 30-50%, or 30-45%.501730 23-1472-WO Embodiment 52. The process according to any of embodiments 1-51, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a C5+selectivity of at least 30%, e.g., at least 40%, or at least 50%, for example, in the range of 30-75%, or 30-70%, or 30-65%, or 30-60%, or 40-75%, or 40-70%, or 40-65%, or 40-60%, or 50-75%, or 50-70%, or 50-65%, or 50-60%. Embodiment 53. The process according to any of embodiments 1-52, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a C2-4selectivity of no more than 30%, e.g., no more than 25%, or no more than 20%, for example, in the range of 10-30%, or 10-25%, or 10-20%, or 15-30%, or 15-25%, or 15-20%. Embodiment 54. The process according to any of embodiments 1-53, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a methane selectivity of no more than 20%, e.g., no more than 15%, or no more than 10%, for example, in the range of 3-20%, or 3-15%, or 3-10%, or 5-20%, or 5-15%, or 5-10%. Embodiment 55. The process according to any of embodiments 1-54, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a CO selectivity of no more than 50%, e.g., no more than 40%, or no more than 30%, e.g., in the range of 10- 50%, or 10-40%, or 10-30%, or 15-50%, or 15-40%, or 15-30%, or 20-50%, or 20-40%, or 20-30%. Embodiment 56. The process according to any of embodiments 1-55, wherein the iron- based FT catalyst has a content of iron of at least 10 wt% iron (e.g., at least 20 wt%, or at least 30 wt%, or at least 40 wt% iron), for example, at least 50 wt%, e.g., at least 60 wt%, or at least 70 wt% iron, on an elemental basis, exclusive of carbon. Embodiment 57. The process according to any of embodiments 1-56, wherein the iron- based FT catalyst is an alkali-promoted iron FT catalyst material. Embodiment 58. The process according to embodiment 57, wherein the iron-based FT catalyst has a concentration of at least 0.5 wt% alkali (e.g., sodium and / or potassium), e.g., at least 1 wt%, on an elemental basis, exclusive of carbon. Embodiment 59. The process according to any of embodiments 1-58, wherein in the range of 50-95 atom% of the iron of the iron-based FT catalyst is in a carbide form, e.g., in the range of 50-90%, or 50-85%, or 50-80%.501730 23-1472-WO Embodiment 60. The process according to any of embodiments 1-59, wherein in the range of in the range of 5-50 atom% of the iron-based FT catalyst is in an oxide phase, e.g., 5-45 atom%, or 5-40 atom%.

[0092] 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.

[0093] The terms “a,” “an,” “the” and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0094] All methods 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.

[0095] 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 of501730 23-1472-WO “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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 upon501730 23-1472-WO reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0101] 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

501730 23-1472-WO We claim:

1. A process for preparing hydrocarbons, comprising providing a feed stream comprising H2, CO, and CO2; contacting the feed stream with an iron-based FT catalyst under conditions to form a product stream comprising C5+hydrocarbons and CO; and recycling at least a portion of the CO of the product stream to the feed stream; wherein the feed stream has a H2partial pressure expressed in bars (i.e., PH2), a CO2partial pressure expressed in bars (i.e., PCO2), and a CO partial pressure expressed in bars (i.e., PCO) such that a value X as defined by the equation X = -80.9156 + 0.6891[PH2] + 79.6799[PCO2 / (PCO+ PCO2)] + 42.3173[PH2 / (2PCO+ 3PCO2)] is at least 0; on a plot of [PCO / PCO2] vs. [PH2 / (PCO+ PCO2)], the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.16[PH2 / (PCO+ PCO2)]; a ratio of [PCO / PCO2] is no greater than 1; and a ratio of [PH2 / (PCO+ PCO2)] is no greater than 3.

2. The process according to claim 1, wherein X is at least 5.

3. The process according to claim 1, wherein X is in the range of 10-60.

4. The process according to any of claims 1-3 wherein the point ([PH2 / (PCO+ PCO2)], [PCO / PCO2]) is above the line [PCO / PCO2] = 0.18 [PH2 / (PCO+ PCO2)].

5. The process according to any of claims 1-4, wherein the ratio [PCO / PCO2] is no more than 0.

8.

6. The process according to any of claims 1-4, wherein the ratio [PCO / PCO2] is in the range of 0.2-0.

7.

7. The process according to any of claims 1-6, wherein the ratio [PH2 / (PCO+ PCO2)] is no greater than 2.

6.

8. The process according to any of claims 1-6, wherein the ratio [PH2 / (PCO+ PCO2)] is in the range of 0.5-2.4.501730 23-1472-WO 9. The process according to any of claims 1-8, wherein a ratio [PH2 / PCO] of the feed stream is no greater than 20.

10. The process according to any of claims 1-8, wherein a ratio [PH2 / PCO] of the feed stream is in the range of 2-10.

11. The process according to any of claims 1-10, wherein the feed stream has a partial pressure of water content of no more than 2% of a total pressure of the feed stream.

12. The process according to any of claims 1-11, wherein the contacting of the feed stream with the iron-based FT catalyst material in the reaction zone is conducted at a temperature in the in the range of 250-400 °C and at a total pressure in the range of 5-100 bar.

13. The process according to any of claims 1-12, wherein the contacting is conducted with a CO2conversion in the range of 10-60%, e.g., 10-55%, or 10-50%, or 10-45%, or 10- 40%, or 20-60%, or 20-55%, or 20-50%, or 20-45%, or 20-40%, or 25-60%, or 25-55%, or 25-50%, or 25-45%, or 25-40%, or 30-60%, or 30-55%, or 30-50%, or 30-45%.

14. The process according to any of claims 1-13, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a C5+selectivity of at least 40% and / or at a C2-4selectivity of no more than 25%,.

15. The process according to any of claims 1-14, wherein the contacting of the feed stream with the iron-based FT catalyst is conducted at a methane selectivity of no more than 15% and / or at a CO selectivity of no more than 40%.

Images