FIELD

[0001] Embodiments disclosed herein relate to processes and systems for making synthesis gas. More particularly, such embodiments relate to the integration of molten carbonate fuel cells and reverse flow reactors for making synthesis gas.

BACKGROUND

[0002] Molten carbonate fuel cells (MCFCs) convert hydrocarbons, e.g ., natural gas, to generate electricity and a synthesis gas that typically has a hydrogen (Eh) to carbon monoxide (CO) molar ratio (Ek:CO) of at least 2.5:1, e.g. , 3:1 to 10:1. Reverse flow reactors (RFRs) can convert steam (EkO), carbon dioxide (CO2), and/or hydrocarbons, e.g. , methane (CEh), to a synthesis gas that typically has a Eh to CO molar ratio of about 2:1 to about 3:1. Various upgrading processes can be used to convert synthesis gas into more valuable products.

[0003] Fischer-Tropsch and methanol synthesis are examples of processes that require a Eh to CO molar ratio of about 2:1, whereas fermentation, i.e ., chemical production via algae or other bio-reaction pathway, is an example of a process that prefers a Eh to CO molar ratio of about 4:1 or even about 5:1. Accordingly, without adjusting the composition of the synthesis gas, the upgrading processes available for synthesis gas produced via the MCFC and the RFR are limited based on the Eh to CO molar ratio in the synthesis gas that each process produces.

[0004] There is a need, therefore, for improved processes and systems for making a synthesis gas with the ability to vary the Eh to CO molar ratio.

SUMMARY

[0005] Processes and systems for making a synthesis gas are provided. In some examples, the process can include reacting a fuel and an oxidant in a combustion zone within a reverse flow reactor under combustion conditions to produce a flue gas that can include CO2 and to heat a conversion zone within the reverse flow reactor to an average conversion zone temperature. The conversion zone can include a reforming catalyst. An anode input stream that can include Eh, a reformable fuel, or a mixture thereof can be introduced into anodes of a plurality of molten carbonate fuel cells. A cathode input stream that can include CO2 and O2 can be introduced into cathodes of the plurality of molten carbonate fuel cells. The plurality of molten carbonate fuel cells can be operated to generate electricity, a cathode exhaust, and an anode exhaust. A reforming input stream that can include a reformable fuel and at least a portion of the anode exhaust can be exposed to the reforming catalyst under reforming conditions that can include the average conversion zone temperature in the conversion zone within the reverse flow reactor to produce a synthesis gas that can have a molar ratio of Eh to CO of 2.5:1 or less. In some examples, at least a portion of the anode exhaust can make up 10 vol% or more of the reforming input stream.

[0006] In some examples, the system for making a synthesis gas can include a reverse flow reactor that can include a first inlet, a second inlet, a first outlet, a second outlet, and a combustion zone and a conversion zone disposed within the reverse flow reactor. The conversion zone can include a catalyst disposed therein. The system can also include a plurality of molten carbonate fuel cells, each molten carbonate fuel cell can include a cathode inlet, a cathode, a cathode outlet, an anode inlet, an anode, and an anode outlet. The second inlet can be in fluid communication with the conversion zone within the reverse flow reactor. One or more of the anode outlets of the plurality of carbonate fuel cells can be in fluid communication with the second inlet of the reverse flow reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 depicts a schematic of an illustrative system for making a synthesis gas, according to one or more embodiments described.

[0008] FIG. 2 depicts a schematic of another illustrative system for making a synthesis gas, according to one or more embodiments described.

DETATEED DESCRIPTION

[0009] All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0010] Unless otherwise specified, all volume amounts (vol%) are based on volume at standard temperature and pressure (20°C, 101 kPa). This allows volume amounts to be specified consistently even though two gas volumes being compared may exist at different temperatures and pressures.

[0011] As used herein, the indefinite article “a” or “an” shall mean “at least one” unless specified to the contrary or the context clearly indicates otherwise. For example, embodiments using “a MCFC” include embodiments where one, two, or more MCFCs are used.

[0012] Nomenclature of elements and groups thereof used herein are pursuant to the Periodic Table used by the International Union of Pure and Applied Chemistry after 1988. An example of the Periodic Table is shown in the inner page of the front cover of Advanced Inorganic Chemistry, 6 ^th Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

Overview

[0013] In various aspects, processes and systems for the production of a synthesis gas via the integration of one or more RFRs and one or more MCFCs are disclosed. The RFR is a reactor that can be used to produce a variety of products via a cyclic reaction process. In some examples, the cyclic reaction process can include a reforming cycle, e.g. , an endothermic reaction, and a regeneration cycle, e.g., an exothermic reaction, that alternate with one another. The endothermic reaction can include hydrocarbon reforming, water gas shift reaction, reverse water gas shift reaction, or a combination thereof. The exothermic reaction can be the reaction of a fuel and an oxidant under combustion conditions. The reforming cycle can convert CO ₂ , hydrocarbons, e.g, CH ₄ , and/or H ₂ O to a synthesis gas that includes Fh and CO. The regeneration cycle can combust reactants, e.g, a fuel and an oxidant, within the RFR to generate heat that can be used to drive the reforming cycle. The MCFC is a reactor that can receive an anode input stream, e.g, H ₂ O and a reformable fuel, and a cathode input stream, e.g, CO ₂ and O ₂ , and can convert the input streams into a cathode exhaust, e.g, low CO ₂ containing product, an anode exhaust, e.g, Fh, CO ₂ , CO, and/or H ₂ O, and also produce electricity.

[0014] It has been discovered that by integrating one or more RFRs and one or more MCFCs, the molar ratio of Fh to CO (Fh:CO molar ratio) of the synthesis gas produced during a reforming cycle of the RFR can be adjusted over a wide range. In some examples, the integration of the RFR and the MCFC can be used to produce a synthesis gas during the reforming cycle of the RFR that can have a Fh:CO molar ratio in a range of from 0.7:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1 to 4:1, 5:1, 6:1, or more. In other examples, the integration of the RFR and the MCFC can be used to produce a synthesis gas during the reforming cycle of the RFR that can have a H2:CO molar ratio of 2.5:1 or less, 2.3:1 or less, 2.1:1 or less, or 2:1 or less. In still other examples, the integration of the RFR and the MCFC can be used to produce a synthesis gas during the reforming cycle of the RFR that can have a H2:CO molar ratio in a range of from 0.7:1 to 6:1, 0.7:1 to 2.5:1, 1:1 to 3:1, 1.5:1 to 4:1, 2:1 to 3:1, 3:1 to 4:1, 4:1 to 5:1, or 5:1 to 6:1.

[0015] The ability to adjust the H2:CO molar ratio of the synthesis gas provides a flexible process that can be combined with a wide variety of synthesis gas upgrading processes. Illustrative synthesis gas upgrading processes can include, but are not limited to, Fischer-Tropsch processes, methanol and/or other alcohol synthesis, e.g, one or more C ₁ -C ₄ alcohols, fermentation processes, separation processes that can separate hydrogen to produce a Fh-rich product, dimethyl ether, and combinations thereof. These synthesis gas upgrading processes are well-known to persons having ordinary skill in the art.

[0016] In some examples, the integration of one or more RFRs and one or more MCFCs can include introducing a reforming input stream that can include at least a portion of the anode exhaust from one or more MCFCs into a conversion or reforming end of the one or more RFRs during the reforming cycle to produce the synthesis gas. In other examples, the integration of the one or more RFRs and the one or more MCFCs can include introducing a cathode input stream that can include at least a portion of a flue gas recovered from the one or more RFRs during the regeneration cycle into one or more cathodes of the one or more MCFCs. In still other examples, the integration of the one or more RFRs and the one or more MCFCs can include introducing the cathode input stream that can include at least a portion of the flue gas recovered from the one or more RFRs into the one or more cathodes of the one or more MCFCs and introducing the reforming input stream that can include at least a portion of the anode exhaust recovered from the one or more MCFCs into the one or more RFRs during the reforming cycle to produce the synthesis gas. In some aspects, a reformable fuel, e.g, CH ₄ , a diluent, e.g. , nitrogen, additional FhO, and/or other fluids can also be introduced with the reforming input stream into the RFR during the reforming cycle. Operation of the RFR

[0017] During the regeneration cycle of the RFR, the fuel and oxidant (and optionally a portion of the anode exhaust) can be introduced into a regeneration end of the RFR. The fuel, oxidant, and optionally the anode exhaust can pass through a recuperation zone and toward a reaction or combustion zone within the RFR. The fuel and oxidant can be reacted under combustion conditions within the combustion zone of the RFR to produce a flue gas and to heat a conversion zone within the RFR to an average conversion zone temperature. Combustion does not occur immediately within the RFR, but instead the location of combustion is controlled to occur within the combustion zone, which can be located toward a middle portion of the RFR. The flow of the reactants continues during the regeneration cycle, leading to additional transfer of heat generated from the combustion of the reactants into the reforming or conversion zone of the reactor. One or more catalysts can be disposed within the conversion zone. The catalyst and internal surfaces of the RFR within the conversion zone of the reactor can be heated to an average conversion zone temperature of 400°C or more. In some examples, the conversion zone can be heated to an average conversion zone temperature of 600°C, 700°C, or 800°C to 1,000°C, 1,300°C, or 1,600°C.

[0018] Illustrative fuels can be or can include, but are not limited to, hydrocarbons, e.g. , methane, ethane, propane, butane, pentane, hydrocarbon containing streams, e.g. , natural gas, Fh, and/or other combustible compounds. The oxidant can be or can include O2. In some examples, the oxidant can be or can include air, O2 enriched air, O2 depleted air, or any other suitable O2 containing stream.

[0019] The flue gas can include, but is not limited to, CO2, O2, nitrogen (N2), CO, unreacted fuel, or any mixture thereof. In some examples, the flue gas can include O2 in a range of from at least 4 vol%, at least 5 vol%, at least 6 vol%, at least 7 vol%, or at least 8 vol% to 10 vol%, 12 vol%, 14 vol%, or 16 vol%. In some examples, the amount of CO2 in the flue gas can be in a range of from 2 vol%, 3 vol%, 4 vol%, or 5 vol% to 6 vol%, 7 vol%, 8 vol%, or 10 vol% of CO2. In some examples, the amount of O2 in the flue gas, on a vol% basis, can be equal to or greater than an amount of CO2 in the flue gas. For example, a ratio of O2 to CO2 in the flue gas can be 1:1, 1.3:1, or 1.5:1 to 1.7:1, 2:1, or 2.3:1. As such, when the cathode input steam includes the flue gas, the cathode input stream can include a greater amount of O2 than CO2. In other examples the amount of CO2 in the flue gas can be greater than the amount of O2 in the flue gas. For example, the ratio of CO2.O2 can be 2:1 or less, 1.7:1 or less, or 1.5:1 or less. In some examples, when the cathode input stream includes the flue gas, the total amount of O2 in the cathode input stream provided by the flue gas can be in a range of from 10 vol%, 20 vol%, 30 vol%, 40 vol% or 50 vol% to 60 vol%, 70 vol%, 80 vol%, 90 vol%, or 100 vol% of. In some examples, when the cathode input stream includes the flue gas, the total amount of CO2 in the cathode input stream provided by the flue gas can be in a range of from 10 vol%, 20 vol%, 30 vol%, 40 vol% or 50 vol% to 60 vol%, 70 vol%, 80 vol%, 90 vol%, or 100 vol%.

[0020] The flue gas can be at a temperature in a range of from 400°C, 500°C, 600°C, or 625°C to 700°C, 750°C, or 800°C upon exiting the RFR. In some examples, the flue gas can be at a pressure of less than 35 kPag, e.g, 0.7 kPag, 2 kPag, 3.5 kPag, 5 kPag, or 10 kPag to 15 kPag, 20 kPag, 25 kPag, or 30 kPag upon exiting the RFR. In other examples, the flue gas can be at a pressure in a range of from 35 kPag to 15 MPag upon exiting the RFR. In still other examples, the flue gas can be at a pressure in a range of from 0.7 kPag, 2 kPag, 5 kPag, 20 kPag, 35 kPag, 50 kPag, or 100 kPag to 200 kPag, 1 MPag, 3 MPag, 5 MPag, 10 MPag, or 15 MPag.

[0021] It has been discovered that by integrating the RFR and the MCFC such that at least a portion of the flue gas contributes toward the cathode input stream, operating the RFR at a lower pressure can provide some significant benefits. For example, typical when the RFR produces a flue gas at a pressure of less than 35 kPag, the flue gas can reduce compression costs associated with compressing the fuel and oxidant for introduction into the RFR during the regeneration cycle and/or can eliminate the need to expand the flue gas prior to introducing the flue gas into the cathodes. In other examples, keeping the flue gas at a pressure greater than 35 kPag, e.g. , up to 15 MPag can improve the efficiency of the RFR by improving heat transfer within the reactor. In some examples, none of the flue gas or less than 1 vol% of the flue gas can be recycled to the combustion zone. In other examples, a portion of the flue gas, i.e., greater than 1 vol% of the flue gas, can be recycled to the combustion zone, e.g. , mixed with the fuel and oxidant supplied thereto. [0022] In various aspects, one or more types of catalyst regeneration can potentially occur during the regeneration step. One type of catalyst regeneration can correspond to removal of coke from the catalyst. During reforming, a portion of the CO2 introduced into the conversion zone can form coke instead of forming CO. This coke can potentially block access to the catalytic sites (such as metal sites) of the catalyst. In some aspects, the rate of formation can be increased in portions of the conversion zone that are exposed to higher temperatures, such as portions of the conversion zone that are exposed to temperatures of 800°C or more, or 900°C or more, or 1,000°C or more. During the regeneration step, oxygen can be present as the temperature of the conversion zone is increased. At the temperatures achieved during regeneration, at least a portion of the coke generated during conversion can be removed as CO or CO2.

[0023] After a sufficient period of time, the regeneration cycle, i.e., the combustion reaction, can be stopped. At least a portion of any remaining combustion products and/or reactants can optionally be purged. The reforming step or reforming cycle can begin. The reactants or reforming input stream, e.g ., at least a portion of the anode exhaust from one or more MCFCs, can be introduced into the reforming end or conversion zone end of the RFR, and thus flow in effectively the opposite direction relative to the flow during regeneration. The heat stored within the reactor during the regeneration step can provide heat for the desired endothermic reaction. The reactants can flow through the conversion zone and can be converted within the conversion zone in the presence of the one or more catalysts disposed therein. In some examples, all of the anode exhaust produced in the MCFC can be introduced into the reforming end or conversion zone end of the RFR. In other examples, 50 vol%, 55 vol%, or 60 vol% to 70 vol%, 80 vol%, 90 vol%, or 95 vol% of the anode exhaust can be introduced into the conversion zone end of the RFR. If less than all of the anode exhaust is introduced into the reforming end of the RFR, the portion that is not can be introduced into the combustion end of the RFR during the regeneration cycle, introduced into the cathode of the MCFC, and/or removed from the process.

[0024] The reforming input stream, e.g. , at least a portion of the anode exhaust and optionally one or more reformable fuels such as CH ₄ , can be exposed to the catalyst under a pressure of less than 35 kPag. For example, the reforming input stream can be exposed to the catalyst under a pressure in a range of from 0.7 kPag, 2 kPag, 3.5 kPag, 5 kPag, or 10 kPag to 15 kPag, 20 kPag, 25 kPag, or 30 kPag. In other examples, the reforming input stream can be exposed to the catalyst under a pressure in a range of from 35 kPag to 15 MPag. In still other examples, the reforming input stream can be exposed to the catalyst under a pressure in a range of from 0.7 kPag, 2 kPag, 5 kPag, 20 kPag, 35 kPag, 50 kPag, or 100 kPag to 200 kPag, 1 MPag, 3 MPag, 5 MPag, 10 MPag, or 15 MPag. In still other examples, the reforming input stream can be exposed to the catalyst under a pressure of less than 2.8 MPag, less than 2.5 MPag, less than 2.2 MPag, or less than 2 MPag. The reforming input stream can have a gas hourly space velocity of 1,000 hr ¹ to 50,000 hr ¹ . The gas hourly space velocity corresponds to the volume of reactants relative to the volume of monolith per unit time. The volume of the monolith is defined as the volume of the monolith as if it was a solid cylinder.

[0025] In various aspects, at least a portion of the catalyst can correspond to a catalyst formed from a ceramic composition as further described herein. As conversion occurs, the heat introduced into the conversion zone during the regeneration cycle can be consumed by the endothermic reforming reactions, e.g ., reverse water gas shift reaction and/or by reforming of hydrocarbons present in the reactants, e.g. , anode exhaust and/or a reformable fuel, which occurs within the conversion zone. After exiting the conversion zone, the conversion products (and unreacted reactants) are no longer exposed to the catalyst. As the conversion products pass through the recuperation zone, heat can be transferred from the products to the recuperation zone. After a sufficient period of time, the conversion process can be stopped, remaining conversion products can optionally be collected or purged from the reactor, and the regeneration cycle can start again. [0026] The catalyst can be or can include a ceramic composition, which can be formed into any convenient shape. In some examples, the ceramic composition can be or can include, but is not limited to, zirconia (ZrO 2), alumina (AI2O3), silica (S1O2), titania (T1O2), magnesia (MgO), pumice, ash, clay, diatomaceous earth, bauxite, and/or other refractory material capable of withstanding temperatures exceeding 1,200°C, or 1,400°C, or 1,600°C. One option can be to extrude or otherwise form a monolith from the ceramic composition. In some aspects, a monolith can include a large plurality of cells or passages that reactant gases can pass through. Because the ceramic composition itself can provide catalytic activity, the ceramic composition can potentially be used without a washcoat. This can allow smaller cell sizes to be used and/or a higher density of cells (such as higher cells per square inch) while still maintaining a desirable pressure drop across the monolith. Conventionally, the addition of a washcoat to a monolith can reduce the available cross-section within a cell for passage of gases. In order to account for this, the monolith structures can be designed with cell sizes large enough to accommodate the presence of a washcoat while still maintaining a desirable pressure drop. In various aspects, because the ceramic composition provides catalytic activity after exposure to the cyclic reaction environment, a washcoat is not necessary for a monolith formed from the composition. This can allow a monolith to be formed with a higher density of cells and/or smaller cells while still providing desirable flow conditions for the gas phase reactants.

[0027] In other aspects, a washcoat can be used in combination with the ceramic composition to provide a monolith (or other catalytic structure) with further enhanced activity. The washcoat can allow the ceramic composition to be impregnated with additional catalytic metal and/or an oxide thereof. One option for incorporating an additional catalytic metal into a washcoat can be to impregnate a catalyst support with the additional catalytic metal, such as by impregnation via incipient wetness. The impregnation can be performed with an aqueous solution of suitable metal salt or other catalytic metal precursor, such as tetramineplatinum nitrate or rhodium nitrate hydrate. The impregnated support can then be dried and/or calcined for decomposition of the catalytic metal precursor. A variety of temperature profiles can potentially be used for the heating steps. One or more initial drying steps can be used for drying the support, such as heating at a temperature from 100°C to 200°C for 0.5 hours to 24 hours. A calcination to decompose the catalytic metal precursor compound can be at a temperature of 200°C to 800°C for 0.5 hours to 24 hours, depending on the nature of the impregnated catalytic metal compound. Depending on the precursor for the catalytic metal, the drying step(s) and/or the decomposing calcination step(s) can be optional. Examples of additional catalytic metals can include, but are not limited to, Ni, Co, Fe, Pd, Rh, Ru, Pt, Ir, Cu, Ag, Au, Zr, Cr, Ti, V, W, alloys thereof, and mixtures thereof.

[0028] The reaction products from the endothermic reaction can pass through the recuperation zone, where a portion of the heat from the reaction products can be transferred to heat transfer surfaces in the recuperation zone. The heat stored in the recuperation zone can then be used to heat at least a portion of the combustion or regeneration flow when the regeneration cycle starts again. This can allow for efficient heating of surfaces and catalyst(s) within the reactor to provide heat for the endothermic reaction, e.g ., a reverse water gas shift reaction and/or reforming of one or more hydrocarbons, while reducing or minimizing incorporation of combustion products into the desired reaction products.

[0029] The reverse water gas shift reaction is a reaction that allows for conversion of CO2 (a relatively inert compound) to CO (a compound that is susceptible to a wider variety of reactions). For example, catalyst and/or reactor configurations for performing Fischer-Tropsch synthesis or methanol synthesis can readily use CO as a reactant, but typically cannot use CO2. The reverse water gas shift reaction converts CO2 and Fh into CO and H2O. As a result, performing the reverse water gas shift reaction can allow CO2 and Fh to be used to produce the synthesis gas.

[0030] The reforming reaction of the reformable fuel, e.g., CFh, can occur in the presence of FhO (steam-reforming), in the presence of CO2 (dry-reforming), or in the presence of both FhO and CO2 (bi-reforming). Examples of stoichiometry for steam, dry, and bi-reforming of CFh are shown in equations (1) - (3).

(1) Dry-Reforming: CH ₄ + C0 ₂ = 2CO + 2H ₂

(2) Steam-Reforming: CFh + FhO = CO + 3Fh

(3) Bi-Reforming: 3CH ₄ + 2H ₂ 0 + C0 ₂ = 4CO + 8H ₂

[0031] As shown in equations (1) - (3), dry reforming can produce lower ratios of Fh to CO than steam reforming. Reforming reactions performed with only steam can generally produce a synthesis gas having a H ₂ :C0 molar ratio of around 3, such as 2.5 to 3.5. In contrast, reforming reactions performed with only CO2 can generally produce a synthesis gas having a H2:CO molar ratio of roughly 1 or even lower. By using a combination of CO2 and H2O during reforming, the reforming reaction can be controlled to generate a wide variety of ¾ to CO ratios in a resulting synthesis gas.

[0032] It should be noted that the ratio of ¾ to CO in a synthesis gas can also be dependent on the water gas shift equilibrium. Although the stoichiometry in Equations (1) - (3) shows ratios of roughly 1 or roughly 3 for dry reforming and steam reforming, respectively, the equilibrium amounts of Eh and CO in a synthesis gas can be different from the reaction stoichiometry. The equilibrium amounts can be determined based on the water gas shift equilibrium, which relates the concentrations of Eh, CO, CO2 and H2O based on the reaction shown in equation (4).

(4) H2O + CO <=> H ₂ + C0 ₂

[0033] Most reforming catalysts, such as rhodium and/or nickel, can also serve as water gas shift catalysts. Thus, if a reaction environment for producing Eh and CO also includes EhO and/or CO2, the initial stoichiometry from the reforming reaction may be altered based on the water gas shift equilibrium. However, this equilibrium is also temperature dependent, with higher temperatures favoring production of CO and H2O. As a result, the ratio of ¾ to CO that is generated when forming synthesis gas is constrained by the water gas shift equilibrium at the temperature in the reaction zone when the synthesis gas is produced.

[0034] Performing the reverse water gas shift reaction in a RFR can provide a variety of advantages. Some advantages are related to the high temperatures that can be achieved in a RFR. In particular, due to a competing equilibrium reaction for formation of methane, the equilibrium conversion of CO2 passes through a minimum at roughly 600°C. By performing the reverse water gas shift reaction at an average conversion zone temperature of 650°C or more, 700°C or more, or 800°C or more, or 900°C or more (such as up to 1,600°C or possibly still higher), the equilibrium conversion of CO2 can be increased while operating at temperatures with relatively fast kinetics. In some examples, the amount of CO2 in the synthesis gas recovered from the RFR can be in a range of from 0.5 vol%, 1 vol%, or 1.5 vol%, to 5.0 vol%, or 0.5 vol% to 3.0 vol%, or 0.5 vol% to 2.5 vol%, or 1.0 vol% to 5.0 vol%, or 1.0 vol% to 3.0 vol%, or 1.0 vol% to 2.5 vol%.

[0035] Other advantages of performing the reverse water gas shift reaction in a RFR can be related to the type of catalyst. For example, catalysts suitable for reforming of hydrocarbons at temperatures of 600°C or more can also be suitable for performing the reverse water gas shift reaction. At a pressure of 1,400 kPag or more, or 2,000 kPag or more, CH4 can be added to a feed that includes CO2, e.g, the anode exhaust, to allow for conversion of the feed by both reforming and reverse water gas shift.

[0036] Still other advantages of using a RFR for performing the reverse water gas shift reaction can be related to thermal management and reaction product management. As discussed above, during the regeneration step of a reaction cycle in a RFR, heat is added to internal surfaces and/or structures, e.g ., catalyst, within the reactor by performing combustion in a combustion zone. The internal surfaces and structures are exposed to the heat generated from combustion, with the heat being distributed by a diluent gas flow. This provides direct internal heating, which can reduce or minimize energy losses relative to indirect methods where an exterior portion of the reactor and/or reaction zone is heated, and thermal diffusion carries the heat from the external location to the interior surfaces where the endothermic reaction (e.g, reverse water gas shift reaction) is performed.

[0037] Yet other advantages of using a RFR for performing the reverse water gas shift reaction can be related to reaction product management. In a RFR, the regeneration step for addition of heat to the reactor occurs during a separate time period than the reaction step for performing the reverse water gas shift reaction (or another desired endothermic reaction). As a result, the combustion products from the regeneration step can be segregated from the reaction products for the reverse water gas shift reaction.

[0038] In some examples, suitable RFRs and operational conditions can include those described in U.S. Patent Nos.: 7,740,829; 8,551,444; 9,687,803; and 10,160,708; and U.S. Patent Application Publication Nos.: 2017/0137285.

Operation of the MCFC

[0039] During operation, a cathode input stream that can include CO2 and O2, e.g, the flue gas recovered from the RFR during the regeneration cycle, can be introduced into a cathode of the MCFC and can be converted to carbonate ions (CO3 ² ), which can then be transported across the molten carbonate electrolyte as a charge carrier. The carbonate ion reacts with Fh in the fuel cell anode to form FhO and CO2. Thus, one of the net outcomes of operating the MCFC is transport of CO2 across the electrolyte. This transport of CO2 across the electrolyte can allow an MCFC to generate electrical power while reducing or minimizing the cost and/or challenge of sequestering carbon oxides from various CO _x -containing streams. A suitable temperature for operation of the MCFC can be around 450°C to 750°C, such as at least 500°C, e.g, with an inlet temperature of about 550°C and an outlet temperature of about 625°C.

[0040] In some examples, any convenient type of electrolyte suitable for operation of a MCFC can be used. Many conventional MCFCs use a eutectic carbonate mixture as the carbonate electrolyte, such as a eutectic mixture of 62 mol% lithium carbonate and 38 mol% potassium carbonate (62% Li ₂ C0 ₃ /38% K2CO3) or a eutectic mixture of 52 mol% lithium carbonate and 48 mol% sodium carbonate (52% Li ₂ C0 ₃ /48% Na ₂ CC> ₃ ). Other eutectic mixtures are also available, such as a eutectic mixture of 40 mol% lithium carbonate and 60 mol% potassium carbonate (40% LhCO3/60% K2CO3). While eutectic carbonate mixtures can be convenient as an electrolyte for various reasons, non-eutectic mixtures of carbonates can also be suitable. Generally, such non eutectic mixtures can include various combinations of lithium carbonate, sodium carbonate, and/or potassium carbonate. Optionally, lesser amounts of other metal carbonates can be included in the electrolyte as additives, such as other alkali carbonates (rubidium carbonate, cesium carbonate), or other types of metal carbonates such as barium carbonate, bismuth carbonate, lanthanum carbonate, or tantalum carbonate.

[0041] In some examples, when operating the MCFC, the anode of the fuel cell can be operated at a traditional fuel utilization value of roughly 60% or 65% to 75%, 80%. When attempting to generate electrical power, operating the anode of the fuel cell at a relatively high fuel utilization can be beneficial for improving electrical efficiency (i.e., electrical energy generated per unit of chemical energy consumed by the fuel cell). It has been discovered that when the anode exhaust is introduced into the RFR during the reforming cycle, it can be beneficial to operate the MCFC at lower fuel utilization to increase in the amount of Fh provided in the anode exhaust for use in the RFR reforming cycle. In some examples, the anode of the fuel cell can be operated at a non- traditional fuel utilization value of roughly 20%, 25%, 30%, or 35% to 40%, 45%, 50%, or 55%. In still other examples, the anode of the fuel cell can be operated at a in a traditional or non- traditional fuel utilization value in a range of from 20%, 25%, 30%, 35% or 50% to 50%, 55%, 60%, 70%, or 80%.

[0042] In some examples, the MCFC can be operated at close to ambient pressure, with substantially the same pressure in the anode and the cathode. Operating at pressures near ambient can simplify maintaining a roughly balanced pressure in the anode and the cathode. Maintaining similar pressures in the anode and cathode can be valuable during operation of the MCFC, due to the nature of how MCFCs are typically constructed. For example, if the pressures in the anode and cathode become sufficiently different, direct transfer of gas from anodes to cathodes (or from cathodes to anodes) can occur due to gas passing through the edge seals within the cell and/or in the manifolds used to feed the anodes and cathodes. Additionally or alternately, variation in pressure between anode and cathode can alter the amount of penetration of the electrolyte into the porous anode and porous cathode materials.

[0043] When using multiple MCFCs, the anode flows and cathode flows through the cells can be arranged in various manners, such as having co-current flow or counter-current flow. In co- current flow, a fuel cell corresponding to a first stage for the anode flow is also the first stage for the cathode. In counter-current flow, a fuel cell corresponding to a first stage for the anode (or cathode) corresponds to a last stage and/or a stage different from the first stage for the cathode (or anode). Additionally, the flow within a single fuel cell can be characterized. For example, in a cross-flow configuration, the direction of flow in the anode for a given fuel cell can be oriented roughly perpendicular to the direction of flow in the anode. A cross-flow configuration is in contrast to an aligned flow configuration, where the direction of flow in the anode can be oriented along roughly the same flow axis as the direction of flow in the cathode. Depending on the aspect, various combinations of fuel cells (such as combinations of fuel cell stacks) can be arranged in series and/or in parallel. In such aspects, for the fuel cells arranged in series, any convenient combination of co-current flow, counter-current flow, cross-current flow, and/or aligned flow can be used.

[0044] In this discussion, a MCFC can correspond to a single cell, with an anode and a cathode separated by an electrolyte. The anode and cathode can receive input gas flows to facilitate the respective anode and cathode reactions for transporting charge across the electrolyte and generating electricity. In some examples, at least a portion of the electricity generated by the MCFC can be used to power one or more compressors or other electrical equipment used within the process or other processes. A fuel cell stack can represent a plurality of MCFCs in an integrated unit. Although a fuel cell stack can include multiple MCFCs, the MCFCs can typically be connected in parallel and can function (approximately) as if they collectively represented a single MCFC of a larger size. When an input flow is delivered to the anode or cathode of a fuel cell stack, the fuel stack can include flow channels for dividing the input flow between each of the MCFCs in the stack and flow channels for combining the output flows from the individual MCFCs. In this discussion, a fuel cell array can be used to refer to a plurality of MCFCs (such as a plurality of fuel cell stacks) that are arranged in series, in parallel, or in any other convenient manner ( e.g ., in a combination of series and parallel). A fuel cell array can include one or more stages of MCFCs and/or fuel cell stacks, where the anode/cathode output from a first stage may serve as the anode/cathode input stream for a second stage. It is noted that the anodes in a fuel cell array do not have to be connected in the same way as the cathodes in the array. For convenience, the input to the first anode stage of a fuel cell array may be referred to as the anode input stream for the array, and the input to the first cathode stage of the fuel cell array may be referred to as the cathode input stream to the array. Similarly, the output from the final anode/cathode stage may be referred to as the anode/cathode output from the array. In aspects where a fuel cell stack includes separate reforming elements, it is noted that the anode input stream flow may first pass through a reforming element prior to entering one or more anodes associated with the reforming element.

[0045] It should be understood that reference to use of a MCFC herein typically denotes a “fuel cell stack” composed of individual fuel cells, and more generally refers to use of one or more fuel cell stacks in fluid communication. Individual fuel cell elements (plates) can typically be “stacked” together in a rectangular array called a “fuel cell stack”. Additional types of elements can also be included in the fuel cell stack, such as reforming elements. This fuel cell stack can typically take a feed stream and distribute reactants among all of the individual fuel cell elements and can then collect the products from each of these elements. When viewed as a unit, the fuel cell stack in operation can be taken as a whole even though composed of many (often tens or hundreds) of individual fuel cell elements. These individual fuel cell elements can typically have similar voltages (as the reactant and product concentrations are similar), and the total power output can result from the summation of all of the electrical currents in all of the cell elements, when the elements are electrically connected in series. Stacks can also be arranged in a series arrangement to produce high voltages. A parallel arrangement can boost the current. If a sufficiently large volume fuel cell stack is available to process a given exhaust flow, the processes and systems described herein can be used with a single MCFC stack. In other aspects, a plurality of fuel cell stacks may be desirable or needed for a variety of reasons.

[0046] Unless otherwise specified, the terms “fuel cell” and “MCFC” are used interchangeably and should be understood to also refer to and/or is defined as including a reference to a fuel cell stack composed of set of one or more individual fuel cell elements for which there is a single input and output, as that is the manner in which fuel cells are typically employed in practice. Similarly, the terms “fuel cells” and “MCFCs” (plural), unless otherwise specified, should be understood to also refer to and/or is defined as including a plurality of separate fuel cell stacks. In other words, all references within this document, unless specifically noted, can refer interchangeably to the operation of a fuel cell stack as a “fuel cell” or as a “MCFC”. For example, the volume of flue gas generated by a commercial scale RFR may be too large for processing by a fuel cell {i.e., a single stack) of conventional size. In order to process the full exhaust, a plurality of fuel cells (i.e., two or more separate fuel cells or fuel cell stacks) can be arranged in parallel, so that each fuel cell can process (roughly) an equal portion of the combustion exhaust. Although multiple fuel cells can be used, each fuel cell can typically be operated in a generally similar manner, given its (roughly) equal portion of the combustion exhaust.

Anode Input Streams

[0047] In various aspects, the anode input stream into the MCFC can be or can include, but are not limited to, hydrogen, a hydrocarbon such as CFk, a hydrocarbonaceous or hydrocarbon-like compound that may contain heteroatoms different from C and H, or any mixture thereof. The source of the hydrogen, hydrocarbon, hydrocarbon-like compounds can be referred to as a fuel source or as a reformable fuel. In some aspects, most of the CH ₄ (or other hydrocarbon, hydrocarbonaceous, or hydrocarbon-like compound) fed to the anode can typically be fresh CH ₄ . In this description, a fresh fuel such as fresh CFErefers to a fuel that is not recycled from another fuel cell process. For example, CFErecycled from the anode outlet stream back to the anode inlet may not be considered “fresh” methane, and can instead be described as reclaimed or recycled

CH ₄ .

[0048] The reformable fuel used can be shared with other components, such as the RFR that can use a portion of the reformable fuel to provide a CCh-containing stream for the cathode input stream (in some examples) and/or to provide a reformable fuel to the conversion zone during the conversion or reforming cycle. The reformable fuel can include water in a proportion to the fuel appropriate for reforming the hydrocarbon (or hydrocarbon-like) compound in the reforming section that generates hydrogen. For example, if CH ₄ is the fuel input for reforming to generate Fh, the molar ratio of water to fuel can be 1 : 1 to 10: 1, such as at least 2:1. A ratio of 4: 1 or greater is typical for external reforming, but lower values can be typical for internal reforming. To the degree that Fh is a portion of the fuel source, in some optional aspects no additional water may be needed in the fuel, as the oxidation of Fh at the anode can tend to produce FhO that can be used for reforming the fuel. The fuel source can also optionally contain components incidental to the fuel source ( e.g ., a natural gas feed can contain some content of CO2 as an additional component). For example, a natural gas feed can contain CO2, N2, and/or other inert (noble) gases as additional components. Optionally, in some aspects the fuel source may also contain CO, such as CO from a recycled portion of the anode exhaust. An additional or alternate potential source for CO in the fuel into a fuel cell assembly can be CO generated by steam reforming of a hydrocarbon fuel performed on the fuel prior to entering the fuel cell assembly.

[0049] More generally, a variety of types of reformable fuel streams may be suitable for use as an anode input stream for the anode of the MCFC. Some fuel streams can correspond to streams containing hydrocarbons and/or hydrocarbon-like compounds that may also include heteroatoms different from C and H. Unless otherwise specified, a reference to a reformable fuel stream containing hydrocarbons for an MCFC anode is defined to include fuel streams containing such hydrocarbon -like compounds. Examples of hydrocarbon (including hydrocarbon-like) reformable fuel streams include natural gas, streams containing C _1- C ₄ carbon compounds (such as CFh or C ₂ H ₆ ), and streams containing heavier C ₅₊ hydrocarbons (including hydrocarbon-like compounds), as well as mixtures thereof. Still other additional or alternate examples of potential fuel streams for use in an anode input stream can include biogas-type streams, such as CH4 produced from natural (biological) decomposition of organic material.

[0050] In some aspects, the MCFC can be used to process an anode input stream, such as a natural gas and/or hydrocarbon stream, with a low energy content due to the presence of diluent compounds. For example, some sources of CH4 and/or natural gas are sources that can include substantial amounts of either CO2 or other inert molecules, such as nitrogen, argon, or helium. Due to the presence of elevated amounts of CO2 and/or inerts, the energy content of a fuel stream based on the source can be reduced. Using a low energy content fuel for a combustion reaction (such as for powering a combustion-powered turbine) can pose difficulties. However, the MCFC can generate power based on a low energy content fuel source with a reduced or minimal impact on the efficiency of the MCFC. The presence of additional gas volume can require additional heat for raising the temperature of the fuel to the temperature for reforming and/or the anode reaction. Additionally, due to the equilibrium nature of the water gas shift reaction within a fuel cell anode, the presence of additional CO2 can have an impact on the relative amounts of ¾ and CO present in the anode exhaust. However, the inert compounds otherwise can have only a minimal direct impact on the reforming and anode reactions. In some examples, the amount of CO2 and/or inert compounds in an anode input stream, when present, can be at least 1 vol%, such as at least 2 vol%, or at least 5 vol%, or at least 10 vol%, or at least 15 vol%, or at least 20 vol%, or at least 25 vol%, or at least 30 vol%, or at least 35 vol%, or at least 40 vol%, or at least 45 vol%, or at least 50 vol %, or at least 75 vol%. In other examples, the amount of CO2 and/or inert compounds in the anode input stream can be 90 vol% or less, such as 75 vol% or less, or 60 vol% or less, or 50 vol% or less, or 40 vol% or less, or 35 vol% or less. In still other examples, the amount of CO2 and/or inert compounds in the anode input stream can be in a range of from 1 vol%, 5 vol%, 10 vol%, 20 vol% 20 vol% or 40 vol% to 60 vol%, 70 vol%, 80 vol%, or 90 vol%.

[0051] Yet other examples of potential sources for an anode input stream can correspond to refinery and/or other industrial process output streams. For example, coking is a common process in many refineries for converting heavier compounds to lower boiling ranges. Coking typically produces an off-gas containing a variety of compounds that are gases at room temperature, including CO and various C1-C4 hydrocarbons. This off-gas can be used as at least a portion of an anode input stream. Other refinery off-gas streams can additionally or alternately be suitable for inclusion in an anode input stream, such as light ends (C1-C4) generated during cracking or other refinery processes. Still other suitable refinery streams can additionally or alternately include refinery streams containing CO or CO2 that also contain ¾ and/or reformable fuel compounds. [0052] Still other potential sources for the anode input stream can additionally or alternately include streams with increased water content. For example, an ethanol output stream from an ethanol plant (or another type of fermentation process) can include a substantial portion of FhO prior to final distillation. Such FhO can typically cause only minimal impact on the operation of a fuel cell. Thus, a fermentation mixture of alcohol (or other fermentation product) and water can be used as at least a portion of the anode input stream.

[0053] Biogas, or digester gas, is another additional or alternate potential source for the anode input stream. Biogas may primarily comprise CFh and CO2 and is typically produced by the breakdown or digestion of organic matter. Anaerobic bacteria may be used to digest the organic matter and produce the biogas. Impurities, such as sulfur-containing compounds, may be removed from the biogas prior to use as the anode input stream.

Anode Exhaust

[0054] The anode exhaust from the MCFC can include FhO, CO2, CO, Fh, or any mixture thereof. Optionally, the anode exhaust could also have unreacted fuel (such as Fh or CFh) or inert compounds in the feed as additional output components. In some examples, the anode exhaust can include primarily FhO, CO2, and Fh and a relatively minor amount of CO. The anode exhaust can include CO2 in an amount in a range of from 20 vol%, 25 vol%, 30 vol%, or 35 vol%, to 40 vol%, 45 vol%, or 50 vol%. The anode exhaust can include FhO in an amount in a range of from 15 vol%, 20 vol%, 25 vol%, or 30 vol% to 35 vol%, 40 vol%, 50 vol%, or 60 vol%. The anode exhaust can include Fh in an amount in a range of from 5 vol%, 10 vol%, 15 vol%, or 20 vol%, to 25 vol%, 30 vol%, 35 vol%, or 40 vol%. The anode exhaust can include CO in an amount in a range of from 1 vol%, 3 vol%, or 5 vol% to 7 vol%, 10 vol%, or 12 vol%. In some examples, the anode exhaust can include 30 vol% to 45 vol% of CO2, 20 vol% to 30 vol% of FhO, 30 vol% to 45 vol% of Fh, and 1 vol% to 10 vol% of CO.

[0055] It should be understood that, prior to introducing at least a portion of the anode exhaust into the RFR during the reforming cycle, the at least a portion of the anode exhaust can be subjected to one or more processes. In some examples, heat can be indirectly transferred from the anode exhaust to heat a fluid medium, such as boiler feed water to produce steam. The anode exhaust, upon exiting the MCFC can be at a temperature in a range of from 525°C, 550°C, or 575°C, to 625°C, 650°C, or 675°C. If the anode exhaust is cooled, the anode exhaust can be cooled to a temperature in a range of from 75°C, 85°C, or 95°C to 100°C, 125°C, or 150°C.

[0056] The at least a portion of the anode exhaust upon exiting the MCFC and/or after cooling can also be compressed prior to introducing the anode exhaust into the RFR. For example, the anode exhaust can be compressed to a pressure up to about 15 MPag. In other examples, the compressed anode exhaust can be at a pressure of less than 2.8 MPag, less than 2.5 MPag, less than 2.2 MPag, or less than 2 MPag. For example, the compressed anode exhaust can be at a pressure of 0.5 MPag, 0.7 MPag, 1 MPag, or 1.3 MPag to 1.5 MPag, 2 MPag, 2.4 MPag, or 2.8 MPag. In some examples, the compressed anode exhaust can include at least 20 vol%, at least 25 vol%, at least 30 vol%, at least 35 vol%, or at least 40 vol% of CO2, at least 20 vol%, at least 25 vol%, at least 30 vol%, at least 35 vol%, or at least 40 vol% of H2O, at least at least 20 vol%, at least 25 vol%, at least 30 vol%, at least 35 vol%, or at least 40 vol% of Fh, and at least 1 vol%, at least 3 vol%, or at least 5 vol% of CO. In other examples, the compressed anode exhaust stream can include 30 vol% to 45 vol% of CO2, 20 vol% to 30 vol% of H2O, 30 vol% to 45 vol% of Fh, and 1 vol% to 10 vol% of CO.

[0057] The compressed anode exhaust introduced into the RFR can optionally be mixed with a reformable fuel such as methane, ethane, propane, butane, pentane, or a mixture thereof. Any reformable fuel discussed herein can optionally be combined with or introduced along with the compressed anode exhaust into the RFR during the reforming cycle.

Cathode Input Stream

[0058] Conventionally, a MCFC can be operated based on drawing a desired load while consuming some portion of the fuel in the anode input stream delivered to the anode. The voltage of the MCFC can then be determined by the load, fuel input to the anode, air and CO2 provided to the cathode, and the internal resistances of the fuel cell. The CO2 to the cathode can be conventionally provided in part by using the anode exhaust as at least a part of the cathode input stream. By contrast, the present invention can use separate/different sources for the anode input stream and cathode input stream. By removing any direct link between the composition of the anode input stream flow and the cathode input stream flow, additional options become available for operating the fuel cell, such as to generate excess synthesis gas, to improve capture of CO2, and/or to improve the total efficiency (electrical plus chemical power) of the fuel cell, among others.

[0059] As noted above, in some examples, the cathode input stream can be or can include at least a portion of the flue gas recovered from the RFR during the regeneration cycle. In other examples, in addition to or in some cases in lieu of using at least a portion of the flue gas from the RFR one or more additional steams containing CO2 and/or O2 can make up at least a portion of the cathode input steam. One example of a suitable C0 ₂ -containing stream for use as a cathode input stream flow can be an output or exhaust flow from one or more different combustion devices. Examples of combustion devices include, but are not limited to, boilers, fired heaters, furnaces, and/or other types of devices that burn carbon-containing fuels in order to heat another substance (such as water or air). [0060] Other potential sources for a cathode input stream can additionally or alternately include sources of bio-produced CO ₂ . This can include, for example, CO ₂ generated during processing of bio-derived compounds, such as CO ₂ generated during ethanol production. An additional or alternate example can include CO ₂ generated by combustion of a bio-produced fuel, such as combustion of lignocellulose. Still other additional or alternate potential CO ₂ sources can correspond to output or exhaust streams from various industrial processes, such as CCh-containing streams generated by plants for manufacture of steel, cement, and/or paper.

[0061] Yet another additional or alternate potential source of CO ₂ can be CCh-containing streams from a fuel cell. The CCh-containing stream from a fuel cell can correspond to a cathode output or cathode exhaust from a different fuel cell, an anode output or anode exhaust from a different fuel cell, a recycle stream from the cathode exhaust to the cathode input stream of a fuel cell, and/or a recycle stream from an anode exhaust to a cathode input stream of a fuel cell. For example, an MCFC operated in standalone mode under conventional conditions can generate a cathode exhaust with a CO ₂ concentration of at least about 5 vol%. Such a CCh-containing cathode exhaust could be used as a cathode input stream for an MCFC operated according to an aspect of the processes and systems described herein. More generally, other types of fuel cells that generate a CO ₂ output from the cathode exhaust can additionally or alternately be used, as well as other types of CCh-containing streams not generated by a “combustion” reaction and/or by a combustion- powered generator. Optionally, a C0 ₂ -containing stream from another fuel cell can be from another MCFC. For example, for MCFCs connected in series with respect to the cathodes, the output from the cathode for a first MCFC can be used as the input to the cathode for a second MCFC.

[0062] As noted above, in addition to CO ₂ , a cathode input stream can include O ₂ to provide the components necessary for the cathode reaction. Some cathode input streams can include air as a component. For example, the flue gas recovered from the RFR can include a sufficient amount of O ₂ by introducing an excess amount of air with the fuel into the RFR during the regeneration cycle. For many types of cathode input streams, the combined amount of CO ₂ and O ₂ can correspond to less than 21 vol% of the input stream, less than 18 vol% of the stream, or less than 17 vol% of the stream. An air stream containing oxygen can be combined with a CO ₂ source that has low oxygen content. For example, an exhaust stream generated by burning coal may include a low oxygen content that can be mixed with air to form a cathode inlet stream.

[0063] In addition to CO ₂ and O ₂ , a cathode input stream can also be composed of other species such as N ₂ , H ₂ O, and other typical oxidant (air) components. For example, for a cathode input stream derived from the flue gas recovered from the RFR and/or an exhaust from another combustion reaction, if air is used as part of the oxidant source for the combustion reaction, the exhaust gas can include typical components of air such as N2, H2O, and other compounds in minor amounts that are present in air. Depending on the nature of the fuel source for the combustion reaction, additional species present after combustion based on the fuel source may include one or more of H2O, oxides of nitrogen (NOx) and/or sulfur (SOx), and other compounds either present in the fuel and/or that are partial or complete combustion products of compounds present in the fuel, such as CO. These species may be present in amounts that do not poison the cathode catalyst surfaces though they may reduce the overall cathode activity. Such reductions in performance may be acceptable, or species that interact with the cathode catalyst may be reduced to acceptable levels by known pollutant removal technologies.

[0064] The amount of O2 present in a cathode input stream (such as an input cathode stream based on a combustion exhaust) can advantageously be sufficient to provide the oxygen needed for the cathode reaction in the fuel cell. Thus, in some examples, the volume percentage of O2 can advantageously be at least 0.3 times, at least 0.4, or at least 0.5 times the amount of CO2 in the exhaust. Optionally, as necessary, additional air can be added to the cathode input stream to provide sufficient oxidant for the cathode reaction.

Cathode Exhaust

[0065] The cathode exhaust can include CO2, N2, other inert gases such as He or Ar, and/or H2O. In some examples, the MCFC can be operated such that the cathode exhaust includes less than 5 vol% CO2, less than 3 vol% CO2, less than 1.5 vol% CO2, less than 1 vol% CO2, or less than 0.5 vol% CO2. In some examples the cathode exhaust can include at least 70 vol%, at least 80 vol%, at least 90 vol%, or at least 95 vol% of N2.

[0066] In some examples, suitable MCFCs and process conditions can include those described inU.S. PatentNos.: 5,084,362; 5,169,717; 9,077,007; 9,647,284; 9,650,246; 9,735,440; 9,755,258; 9,774,053; 9,786,939; 9,819,042; 9,923,219; 9,941534; 10,093,997; and 10,283,802.

[0067] FIG. 1 depicts a schematic of an illustrative system 100 for making a synthesis gas via line 178, according to one or more embodiments. The system 100 can include one or more RFRs 110, one or more MCFCs 130, one or more compressors (two are shown) 140, 170, and one or more heat exchangers (two are shown) 150, 160. In some embodiments, the system 100 can also include one or more synthesis gas upgrading units 180. The RFR 110 can include a first inlet 111, a second inlet 112, a first outlet 120, and a second outlet 121. A combustion zone 113 and a conversion zone 119 can be located within the RFR 110. One or more catalysts 115 can be disposed within the conversion zone 119 of the RFR 110. The MCFC 130 can include one or more cathode inlets 131, one or more cathodes 132, one or more cathode outlets 133, one or more anode inlets 135, one or more anodes 136, and one or more anode outlets 137. An electrolyte 139 can be disposed between the cathode 132 and the anode 136.

[0068] During a regeneration cycle of the RFR 110, a fuel via line 102 and an oxidant via line 104 can be mixed or otherwise combined and introduced via line 106 into the first compressor 140. A compressed mixture of the fuel and oxidant can be recovered via line 108 and introduced into the first inlet 111 of the RFR 110. The compressed mixture can be reacted within the combustion zone 113 within the RFR 110 under combustion conditions to produce a flue gas that can include CO2 and O2 and to heat the conversion zone 119 within the RFR 110 to an average conversion zone temperature, e.g ., 400°C of more. The combustion of the fuel within the combustion zone 113 can heat inner surfaces within the RFR 110 and the catalyst 115 disposed within the conversion zone 119. The conversion zone 119 and catalyst 115 disposed therein can be downstream of the combustion zone 113 relative to the flow path of the fuel and oxidant within the RFR 110. The flue gas via line 125 can be recovered from the first outlet 120 of the RFR 110.

[0069] In some examples, the flue gas in line 125 can be at a pressure of less than 35 kPag, e.g. , 3.5 kPag to 25 kPag. In other examples, the flue gas in line 125 can be at a pressure of 3.5 kPag to 15 MPag or 35 kPag to 15 MPag. The amount of O2 in the flue gas in line 125 can be in a range of from 3 vol%, 4 vol%, 5 vol%, or 6 vol% to 8 vol%, 10 vol%, 12 vol%, 14 vol%, or 16 vol%. The amount of CO2 in the flue gas in line 125 can be in a range of from 2 vol%, 3 vol%, 4 vol%, or 5 vol% to 6 vol%, 7 vol%, 8 vol%, or 10 vol% of CO2. In some examples, the flue gas can include, on a vol% basis, a greater amount of O2 than CO2.

[0070] At least a portion of the flue gas via line 125 can be introduced into the cathode inlet 131 and can flow into the cathode 132 of the MCFC 130. In some examples, the amount of O2 the flue gas in line 125 can contribute toward the total amount of O2 introduced into the cathode inlet 131 can be in a range of from 50 vol%, 60 vol%, or 70 vol% to 80 vol%, 90 vol%, or 100 vol%. In some examples, the amount of CO2 the flue gas in line 125 can contribute toward the total amount of CO2 introduced into the cathode inlet 131 can be in a range of from 50 vol%, 60 vol%, or 70 vol% to 80 vol%, 90 vol%, or 100 vol%.

[0071] A cathode exhaust via line 134 can be recovered from the cathode outlet 133 of the MCFC 130. In some examples, the cathode exhaust via line 134 can be vented to the atmosphere, cooled via the first heat exchanger 150, treated to remove at least a portion of any impurities, etc. Preferably, the cathode exhaust in line 134 can be cooled to recover heat, e.g. , produce steam, and a cooled cathode exhaust via line 152.

[0072] An anode input steam via line 126 can be introduced into the anode inlet 135 and can flow into the anode 136 of the MCFC 130. An anode exhaust via line 138 can be recovered from the anode outlet 137. In some examples, at least a portion of the anode exhaust via line 138 can be introduced into the second compressor 170 to produce a compressed anode exhaust via line 172. In some examples, the compressed anode exhaust in line 172 can be at a pressure of up to about 15 MPag. In other examples, the compressed anode exhaust in line 172 can be at a pressure in a range of from 0.5 MPag, 0.7 MPag, 1 MPag, or 1.3 MPag to 1.5 MPag, 2 MPag, 2.4 MPag, or 2.8 MPag.

[0073] In other examples, at least a portion of the anode exhaust via line 138 can be cooled via indirect heat exchange within the second heat exchanger 160 to produce a cooled anode exhaust via line 162 and a heated medium, e.g ., indirect heating of boiler feed water to produce steam. At least a portion of the cooled anode exhaust via line 162 can be introduced into the second compressor 170 to produce the compressed anode exhaust via line 172.

[0074] During the reforming cycle of the RFR 110, at least a portion of the compressed anode exhaust in line 172 can be introduced into the second inlet 112 of the RFR 110 and the anode exhaust can flow into the conversion zone 119. In some examples, Fh, a reformable fuel, or a mixture thereof via line 173 can be combined with the compressed anode exhaust in line 172 to produce a mixture and the mixture via line 174 can be introduced into the second inlet 112 of the RFR. The addition of Fh, reformable fuel, or mixture thereof to the anode exhaust can be used to adjust the Fh:CO molar ratio in the synthesis gas recovered via line 178. Suitable reformable fuels can be or can include, but are not limited to, methane, ethane, propane, butane, pentane, or a mixture thereof.

[0075] In some examples, a first portion of the anode exhaust via line 172 can be introduced into the second inlet 112 of the RFR 110 and a second portion of the anode exhaust via line 175 can be introduced into the inlet 111 (during the regeneration cycle) with the compressed fuel and oxidant in line 108. By reducing the amount of anode exhaust introduced into the RFR via line 172, 174, the Fh:CO molar ratio of the synthesis gas recovered via line 178 can be adjusted. In some examples, 50 vol%, 55 vol%, or 60 vol% to 70 vol%, 80 vol%, 90 vol%, or 95 vol% of the anode exhaust in line 172 can be introduced into the second inlet 112 of the RFRl 10.

[0076] At least a portion of the anode exhaust and the optional reformable fuel and/or Fh can be reformed within the conversion zone 119 in the presence of the catalyst 115 to produce the synthesis gas in line 178 that can include Fh and CO. The synthesis gas via line 178 can be recovered from the second outlet 121 of the RFR 110. The synthesis gas in line 178 can have a can have a Fh:CO molar ratio in a range of from 0.7:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1 to 4:1, 5:1, 6:1, or more. In other examples, the synthesis gas in line 179 can have a Fh:CO molar ratio of 2.5:1 or less, 2.3 : 1 or less, 2.1:1 or less, or 2: 1 or less. [0077] The synthesis gas via line 178 can be introduced into one or more synthesis gas upgrading units 180. The synthesis upgrading unit 180 can be or can include a wide variety of upgrading processes and systems. Illustrative synthesis gas upgrading units can be or can include, but are not limited to, Fischer-Tropsch systems, methanol and/or other alcohol synthesis systems, fermentation systems, separation systems, e.g ., pressure swing adsorption unit, that can separate hydrogen to produce a Fh-rich product, and combinations thereof. An upgraded product via line 182 can be recovered from the upgrading unit 180. In some examples, the upgraded product can include, but is not limited to, methanol, syncrude, diesel, lubricants, waxes, olefins, dimethyl ether, other chemicals, or any combination thereof.

[0078] FIG. 2 depicts a schematic of an illustrative system 200 for making a synthesis gas via line 288, according to one or more embodiments. The system 200 can include one or more RFRs 210, one or more MCFCs (two are shown) 230, 240, one or more compressors (two are shown) 250, 280, and one or more heat exchangers (two are shown) 260, 270. In some embodiments, the system 200 can also include one or more synthesis gas upgrading units 290. The RFR 210 can include a first inlet 211, a second inlet 212, a first outlet 220, and a second outlet 221. A combustion zone 213 and a conversion zone 219 can be located within the RFR 210. One or more catalysts 215 can be disposed within the conversion zone 219 of the RFR 210. Each MCFC 230, 240 can include one or more cathode inlets 231, one or more cathodes 232, one or more cathode outlets 233, one or more anode inlets 235, one or more anodes 236, and one or more anode outlets 237. An electrolyte 239 can be disposed between the cathode 232 and the anode 236 in each MCFC 230, 240.

[0079] During a regeneration cycle of the RFR 210, a fuel via line 202 and an oxidant via line 204 can be mixed or otherwise combined and introduced via line 206 into the first compressor 250. A compressed mixture of the fuel and oxidant via line 208 can be recovered from the first compressor 250 and introduced into the first inlet 211 of the RFR 210. The compressed mixture can be reacted within the combustion zone 213 within the RFR 210 under combustion conditions to produce a flue gas that can include CO2 and O2 and to heat the conversion zone 219 within the RFR 210 to an average conversion zone temperature, e.g. , 400°C of more. The combustion of the fuel within the combustion zone 213 can heat inner surfaces of the RFR 210 and the catalyst 215 disposed within a conversion zone 219 within the RFR 210. The conversion zone 219 and catalyst 215 disposed therein can be downstream of the combustion zone 213 relative to the flow path of the fuel and oxidant within the RFR 210. The flue gas via line 222 can be recovered from the first outlet 220 of the RFR 210.

[0080] In some examples, the flue gas in line 222 can be at a pressure of less than 35 kPag, e.g, 3.5 kPag to 25 kPag. In other examples, the flue gas in line 222 can be at a pressure in a range of from 35 kPag to 15 MPag. The amount of O2 in the flue gas in line 222 can be in a range of from 3 vol%, 4 vol%, 5 vol%, or 6 vol% to 8 vol%, 10 vol%, 12 vol%, or 15 vol% of O2. The amount of CO2 in the flue gas in line 222 can be in a range of from 2 vol%, 3 vol%, 4 vol%, or 5 vol% to 6 vol%, 7 vol%, 8 vol%, or 10 vol% of CO2. In some examples, the flue gas in line 222 can include, on a vol% basis, a greater amount of O2 than CO2.

[0081] In some examples, the flue gas in line 222 can be sent to a steam recovery or other heat recover unit to produce a cooled flue gas that can be vented to the atmosphere. In other examples, the flue gas in line 222 can be introduced into a combustor or otherwise subjected to one or more processes to remove one or more impurities that can be present prior to venting to the atmosphere. In other examples, at least a portion of the flue gas via 223 and 224, can be introduced into the cathode inlets 231 of the MCFCs 230, 240, respectively, and can flow into the cathodes 232 of the MCFCs 230, 240. In some examples, the amount of O2 the flue gas in line 222 can contribute toward the total amount of O2 introduced into the cathode inlets 231 can be in a range of from 50 vol%, 60 vol%, or 70 vol% to 80 vol%, 90 vol%, or 100 vol%. In some examples, the amount of CO2 the flue gas in line 222 can contribute toward the total amount of CO2 introduced into the cathode inlets 231 can be in a range of from 50 vol%, 60 vol%, or 70 vol% to 80 vol%, 90 vol%, or 100 vol%. In other examples, another gas in line 225 can be introduced via lines 226 and 227 into the cathode inlets 231 of the MCFCs 230, 240, respectively. The gas in line 225 can include O2 and CO2 and can have the same or similar composition as the flue gas in line 222. The gas in line 225 can be recovered from one or more other combustion units, e.g. , a combustion turbine, produced from mixing air and CO2 recovered from one or more processes, or otherwise acquired from any suitable source.

[0082] A cathode exhaust via lines 234 and 244 can be recovered from the cathode outlets 233 of the MCFCs 230, 240. In some examples, the cathode exhaust via lines 234 and 244 can be vented to the atmosphere, cooled via the first heat exchanger 260, treated to remove at least a portion of any impurities, etc. Preferably, the cathode exhaust in lines 234 and 244 can be combined to produce a mixed exhaust via line 246 that can be cooled to recover heat, e.g. , produce steam, via the first heat exchanger 260 and a cooled cathode exhaust via line 262.

[0083] An anode input steam via line 228 can be introduced into the anode inlets 235 of the MCFCs 230, 240 and can flow into the anodes 236 of the MCFCs 230, 240. An anode exhaust via lines 238 and 248 can be recovered from the anode outlets 237 of the MCFCs 230, 240, respectively. In some examples, at least a portion of the anode exhaust via lines 238 and 248 can be combined to produce a combined anode exhaust via line 249. The combined anode exhaust in line 249 can be introduced into the second compressor 280 to produce a compressed anode exhaust via line 282. In some examples, the compressed anode exhaust can be at a pressure of up to about 15 MPag. In other examples, the anode exhaust introduced into the RFR via line 282 can be at a pressure of 0.5 MPag, 0.7 MPag, 1 MPag, or 1.3 MPag to 1.5 MPag, 2 MPag, 2.4 MPag, or 2.8 MPag.

[0084] In other examples, at least a portion of the combined anode exhaust via line 249 can be cooled via indirect heat exchange within the second heat exchanger 270 to produce a cooled anode exhaust via line 272 and a heated medium, e.g ., indirect heating of boiler feed water to produce steam. At least a portion of the cooled anode exhaust via line 272 can be introduced into the second compressor 280 to produce the compressed anode exhaust via line 282.

[0085] During a reforming cycle of the RFR 210, the at least a portion of the compressed anode exhaust via line 282 can be introduced into the second inlet 212 of the RFR 210 and the anode exhaust can flow into the conversion zone 219. In some examples, Fh, a reformable fuel, or a mixture thereof via line 283 can be combined with the compressed anode exhaust in line 282 to produce a mixture and the mixture via line 284 can be introduced into the second inlet 212 of the RFR 210. The addition of Fh, reformable fuel, or mixture thereof to the anode exhaust can be used to adjust the Fh:CO molar ratio in the synthesis gas recovered via line 288. Suitable reformable fuels can be or can include, but are not limited to, methane, ethane, propane, butane, pentane, or a mixture thereof.

[0086] In some examples, a first portion of the anode exhaust via line 282 can be introduced into the second inlet 212 of the RFR 210 and a second portion of the anode exhaust via line 285 can be introduced into the inlet 211 (during the regeneration cycle) with the compressed fuel and oxidant in line 208. By reducing the amount of anode exhaust introduced into the RFR 210 via line 282, 284, the Fh:CO molar ratio of the synthesis gas recovered via line 288 can be adjusted. In some examples, 50 vol%, 55 vol%, or 60 vol% to 70 vol%, 80 vol%, 90 vol%, or 95 vol% of the anode exhaust in line 282 can be introduced into the second inlet 212 of the RFR 210.

[0087] At least a portion of the anode exhaust and the optional reformable fuel and/or Fh can be reformed within the conversion zone 219 in the presence of the catalyst 215 to produce the synthesis gas in line 288 that can include Fh and CO. The synthesis gas via line 288 can be recovered from the second outlet 221 of the RFR 210. The synthesis gas in line 288 can have a can have a Fh:CO molar ratio of 0.7:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1 to 4:1, 5:1, 6:1, or more. In other examples, the synthesis gas in line 288 can have a Fh:CO molar ratio of 2.5:1 or less, 2.3:1 or less, 2.1:1 or less, or 2: 1 or less.

[0088] The synthesis gas via line 288 can be introduced into one or more synthesis gas upgrading units 290. The synthesis upgrading unit 290 can be or can include a wide variety of upgrading processes and systems. Illustrative synthesis gas upgrading units can be or can include, but are not limited to, Fischer-Tropsch systems, methanol and/or other alcohol synthesis systems, fermentation systems, separation systems, e.g ., pressure swing adsorption unit, that can separate hydrogen to produce a Fh-rich product, and combinations thereof. An upgraded product via line 292 can be recovered from the upgrading unit 290. In some examples, the upgraded product can include, but is not limited to, methanol, syncrude, diesel, lubricants, waxes, olefins, dimethyl ether, other chemicals, or any combination thereof.

Example

[0089] High RFR regeneration exit temperatures improve methane conversion, but reduce thermal efficiency. Therefore, normal operation keeps RFR regeneration exit temperatures in the 250°C to less than 600°C. MCFCs typically operate, however, at a temperature of 600°C to 650°C, making high regeneration exit temperatures the preferred operational mode for the RFR when integrated with the MCFC. Modeling was carried out to compare the effect of exit temperature on conversion during the reforming cycle of the RFR. The same amount of methane is processed and the conversion of methane to synthesis gas improved from 50% to 76% by increasing the regeneration exit temperature from 450°C to 600°C. Exit temperatures greater than 600°C are not normally preferred due to the lack of thermal efficiency of the process (see hydrogen fuel use nearly doubles for the case below). Table 1 shows the regeneration input flows that were used during the modeling.

Table 1 - Reforming Results versus Regeneration Exhaust Temperature

[0090] As shown in Table 1, in order to achieve the greater regeneration temperature profile, an increased amount of gas flow was used during the regeneration step relative to the input gas flow for the lower regeneration temperature profile. It is noted that a small excess of H ₂ was included in the gas flow (XH2) relative to the stoichiometric combustion amount. The increased flow to achieve the greater regeneration temperature profile included increasing the amount of Fh, therefore allowing more heat to be added to the RFR during regeneration. This additional heat allows for a substantial increase in the amount of methane that converts during the reforming portion of the reaction cycle, from 52% conversion to 76% conversion. It is noted that for the purpose of this example, the temperature profiles were selected to have less than 90% conversion, so that the benefits of increasing the flue gas exhaust temperature would be clear. In other aspects, increases in the flue gas exhaust temperature can be used with reforming conditions that result in 90% or more conversion of methane and/or other hydrocarbons. In such a situation where the conversion is already relatively high, increasing the amount of heat available in the reactor can allow for reforming of an increased amount of methane and/or other hydrocarbons.

[0091] The RFR combustion normally produces a flue gas that includes less than 1% O2 to reduce the load in the main air compressor. By integrating the RFR with the MCFC such that the flue gas from the RFR is introduced into the cathode of the MCFC, additional excess air is fed into the RFR during the regeneration cycle to provide sufficient O2 to the MCFC. By increasing the air supplied to the RFR, the diluent recycle on the RFR regeneration is eliminated. The result is doubling of the “normal” air flow rate into the RFR and eliminating the mostly nitrogen/moisture recycle stream conventionally required during operation of the RFR. For the simulated example above, we use 690 MMSCFD of air flow in the case instead of 350 MMSCFD under normal operation with a similar syngas generation.

[0092] Normally, when reforming or performing reforming/WGS/RWGS in an RFR, high pressure regeneration is preferred to minimize pressure drop through the beds. By integrating the RFR with the MCFC, however, a low pressure flue gas can be generated such that just a few psig at the regeneration outlet is generated that can be used directly by the MCFC.

[0093] This disclosure may further include the following non-limiting embodiments.

[0094] Embodiment 1. A process for making a synthesis gas, comprising: reacting a fuel and an oxidant in a combustion zone within a reverse flow reactor under combustion conditions to produce a flue gas comprising CO2 and to heat a conversion zone within the reverse flow reactor to an average conversion zone temperature, the conversion zone comprising a reforming catalyst; introducing an anode input stream comprising Eh, a reformable fuel, or a mixture thereof into anodes of a plurality of molten carbonate fuel cells; introducing a cathode input stream comprising CO2 and O2 into cathodes of the plurality of molten carbonate fuel cells; operating the plurality of molten carbonate fuel cells to generate electricity, a cathode exhaust, and an anode exhaust; and exposing a reforming input stream comprising a reformable fuel and at least a portion of the anode exhaust to the reforming catalyst under reforming conditions comprising the average conversion zone temperature in the conversion zone within the reverse flow reactor to produce a synthesis gas having a molar ratio of Eh to CO of 2.5 : 1 or less, wherein the at least a portion of the anode exhaust makes up 10 vol% or more of the reforming input stream.

[0095] Embodiment 2. The process of embodiment 1, wherein the at least a portion of the anode exhaust makes up 30 vol% or more (or 50 vol% or more) of the reforming input stream. [0096] Embodiment 3. The process of embodiment 1 or 2, wherein the reforming input stream comprises the reformable fuel, the at least a portion of the anode exhaust flow, and 10 vol% or less of additional components.

[0097] Embodiment 4. The process of any of embodiments 1 to 3, wherein the flue gas further comprises O2, and wherein the cathode input stream comprises at least a portion of the flue gas. [0098] Embodiment 5. The process of embodiment 4, wherein the flue gas comprises 4 vol% or more of O2.

[0099] Embodiment 6. The process of embodiment 4, wherein the flue gas comprises 6 vol% to 12 vol% of O2.

[0100] Embodiment 7. The process of any of embodiments 4 to 6, wherein the flue gas contributes 50 vol% or more (or 90 vol% or more) of a total amount of O2 in the cathode input stream.

[0101] Embodiment 8. The process of any of embodiments 1 to 5, wherein the cathode input stream comprises, on a vol% basis, a greater amount of O2 than CO2.

[0102] Embodiment 9. The process of any of embodiments 1 to 8, wherein the synthesis gas comprises a molar ratio of Eh to CO of 2.3:1 or less, or 2.1:1 or less, or 1.8:1 or less.

[0103] Embodiment 10. The process of any of embodiments 1 to 9, wherein the average conversion zone temperature is 400°C or more.

[0104] Embodiment 11. The process of any of embodiments 1 to 10, wherein, upon exiting the combustion zone, the flue gas is at a pressure of less than 35 kPag.

[0105] Embodiment 12. The process of any of embodiments 1 to 11, wherein, upon exiting the combustion zone, the flue gas is at a pressure of 3.5 kPag to 25 kPag.

[0106] Embodiment 13. The process of any of embodiments 1 to 10, wherein, upon exiting the combustion zone, the flue gas is at a pressure of 35 kPag to 15 MPag.

[0107] Embodiment 14. The process of any of embodiments 1 to 13, wherein less than 1 vol% of the flue gas is recycled to the combustion zone.

[0108] Embodiment 15. The process of any of embodiments 1 to 14, further comprising compressing at least a portion of the anode exhaust to produce a compressed anode exhaust, wherein the at least a portion of the anode exhaust exposed to the reforming catalyst under the reforming conditions comprises at least a portion of the compressed anode exhaust.

[0109] Embodiment 16. The process of embodiment 15, wherein the compressed anode exhaust is at a pressure of less than 2.8 MPag.

[0110] Embodiment 17. The process of embodiment 15 or 16, wherein the compressed anode exhaust is at a pressure of less than 2.2 MPag.

[0111] Embodiment 18. The process of embodiment 15 or 16, wherein the compressed anode exhaust is at a pressure of 0.7 MPag to 2.8 MPag.

[0112] Embodiment 19. The process of any of embodiments 1 to 18, wherein each reformable fuel independently comprise methane, ethane, propane, butane, pentane, or a mixture thereof. [0113] Embodiment 20. The process of any of embodiments 1 to 19, wherein the reforming catalyst comprises Ni, Co, Fe, Pd, Rh, Ru, Pt, Ir, Cu, Ag, Au, Zr, Cr, Ti, V, W, or a combination thereof.

[0114] Embodiment 21. A system for making a synthesis gas, comprising: a reverse flow reactor comprising a first inlet, a second inlet, a first outlet, a second outlet, and a combustion zone and a conversion zone disposed within the reverse flow reactor, the conversion zone comprising a catalyst disposed therein; and a plurality of molten carbonate fuel cells each comprising a cathode inlet, a cathode, a cathode outlet, an anode inlet, an anode, and an anode outlet, wherein: the second inlet is in fluid communication with the conversion zone within the reverse flow reactor, and one or more of the anode outlets of the plurality of carbonate fuel cells is in fluid communication with the second inlet of the reverse flow reactor.

[0115] Embodiment 22. The system of claim 21, wherein the first outlet is in fluid communication with one or more of the cathode inlets of the plurality of molten carbonate fuel cells.

[0116] Embodiment 23. The system of embodiment 21 or 22, further comprising a compressor having a compressor inlet and a compressor outlet, wherein the compressor inlet is in fluid communication with one or more of the anode outlets, and wherein the second inlet is in fluid communication with the compressor outlet.

[0117] Embodiment 24. The system of embodiment 23, wherein the compressor is configured to compress an anode exhaust to a pressure of from 0.7 MPag to less than 2.8 MPag.

[0118] Embodiment 25. The system of embodiment 23 or 24, wherein the compressor is configured to compress an anode exhaust to a pressure of 0.7 MPag to 2.2 MPag.

[0119] Embodiment 26. The system of any of embodiments 21 to 25, wherein the first inlet comprises a fuel inlet and an oxidant inlet, and wherein the fuel inlet and the oxidant inlet have separate flow paths within the reverse flow reactor into the combustion zone. [0120] Embodiment 27. The system of any of embodiments 21 to 26, wherein the first inlet is configured to introduce a fuel and an oxidant into the combustion zone to produce a flue gas and to heat the conversion zone during a regeneration cycle.

[0121] Embodiment 28. The system of any of embodiments 21 to 27, wherein each anode inlet is configured to introduce an anode input stream comprising Eh, a reformable fuel, or a mixture thereof into the anode.

[0122] Embodiment 29. The system of any of embodiments 21 to 28, wherein the second inlet is configured to introduce at least a portion of the anode exhaust into the conversion zone during a reforming cycle.

[0123] Embodiment 30. The system of any of embodiments 21 to 29, wherein the conversion zone is configured to facilitate endothermic conversion of the at least a portion of the anode exhaust during a reforming cycle.

[0124] Embodiment 31. The system of any of embodiments 21 to 30, wherein the second outlet is configured to discharge a synthesis gas from the reverse flow reactor.

[0125] Embodiment 32. The system of any of embodiments 21 to 31, wherein the second outlet is in fluid communication with a pressure swing adsorption unit, a fermentation unit, a Fischer-Tropsch unit, or a C1-C4 alcohol production unit.

[0126] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g ., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below.

[0127] Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.

[0128] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.