Reverse Water Gas Shift Catalytic Reactor System

Abstract

The present invention describes methods, systems, and catalysts for utilizing carbon dioxide into high quality synthesis gas that can be used to produce fuels (e.g., diesel fuel) and chemicals. In one aspect, the present invention provides a method for converting a feed gas comprising carbon dioxide and hydrogen into a product gas comprising carbon monoxide and water.

Description

[Technical field]

[0001] The present invention describes an improved catalytic reactor and related methods for utilizing carbon dioxide into high quality synthesis gas, which can in turn be used to produce fuels (e.g., diesel fuel, jet fuel, gasoline, kerosene, etc.), chemicals, and other products. [Background technology]

[0002] Carbon dioxide is produced in many industrial and biological processes. It is usually emitted into the atmosphere. However, carbon dioxide is recognized as a significant greenhouse gas, and there is a need to reduce carbon dioxide emissions from these processes. Carbon dioxide may be used in limited cases to enhance oil and gas recovery from oil wells, but most is emitted into the atmosphere. A preferred way to deal with carbon dioxide is to efficiently capture and utilize it, converting it into useful products, such as fuels and chemicals, that can replace fuels and chemicals produced from fossil resources, such as oil and natural gas, thereby reducing the total net emissions of carbon dioxide into the atmosphere.

[0003] One reaction that has been considered for the utilization of carbon dioxide is the Reverse Water Gas Shift (RWGS) reaction, often referred to as the hydrogenation of carbon dioxide.

[0004] [ka]

[0005] This reaction converts carbon dioxide and hydrogen to carbon monoxide and water. The reaction is endothermic at room temperature and requires heat to proceed. To achieve significant conversion of carbon dioxide to carbon monoxide with minimal or no coking (carbon formation), elevated temperatures and an efficient catalyst are required.

[0006] Hydrogen (H2) can be produced from many sources, including natural gas, or, more preferably, Preferably, it can be produced from water via electrolysis or other means.

[0007] [ka]

[0008] There is the potential for useful products using CO (carbon monoxide) from the RWGS reaction and H2 from the electrolysis of water. The mixture of H2 and CO is called synthesis gas or syngas. Syngas can be used as a feedstock to produce a wide range of chemical products, including liquid and gaseous hydrocarbon fuels, alcohols, acetic acid, dimethyl ether, and many other chemical products.

[0009] Several catalysts for the RWGS reaction have been disclosed. The main catalysts previously investigated were Cu or Pt or Rh dispersed on metal oxide supports (Daza & Kuhn, RSC Adv. 2016, 6, 49675-49691). Summary of the Invention [Problem to be solved by the invention]

[0010] Despite several reports, there remains a need for new methods, systems and catalysts related to RWGS chemistry. [Means for solving the problem]

[0011] The present invention relates to a process for converting a feed gas containing carbon dioxide and hydrogen to a product gas containing carbon monoxide and water. The feed gas is heated to a temperature of at least 1,400° F. in a preheater external to a primary reactor vessel. (760℃) Higher than 1,500°F (816℃)Higher than 1,600°F, preferably (871℃) The preheater is heated to an inlet temperature greater than the inlet temperature to produce a heated feed gas. The preheater generates heat using electricity and transfers the heat to produce a heated feed gas. The heated feed gas is sent to a main reactor. The main reactor is an adiabatic or nearly adiabatic vessel that minimizes heat loss. The main reactor contains a catalyst that converts the heated feed gas to a product gas. The product gas leaves the main reactor at an outlet temperature, which is lower than the inlet temperature. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 shows an integrated, highly efficient process for the hydrogenation of carbon dioxide using reverse water gas shift and a unique methodology for efficient conversion.

[0013] [Diagram 2] The general layout of the unique reverse water gas shift reactor and associated equipment is shown in Figure 2. Specifically, Figure 2 shows a cross exchanger that preheats the feed H2 and CO2 with the hot syngas product exiting the RWGS, then an electric heater that brings the H2 and CO2 to reaction temperature, and finally the RWGS reactor vessel with the catalyst that converts the H2 and CO2 to CO and HO. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Figure 1 shows the flowsheet of the RWGS reactor. Hydrogen is one of the feed gases and water is It can be produced by electrolysis.

[0015] [ka]

[0016] Hydrogen can also be produced by steam reforming of hydrocarbons such as methane or natural gas.

[0017] [ka]

[0018] Carbon dioxide can come from many industrial and natural sources. CO2 is often found in natural gas deposits. CO2 is emitted from many biological processes, such as anaerobic digestion. Many other processes (e.g., power plants, cement plants, ethanol production, oil refineries, chemical plants, etc.) produce carbon dioxide that is usually emitted into the atmosphere. CO2 is also found in the atmosphere. CO2 can be recovered from these biological, industrial and atmospheric processes by many known techniques and used as a feedstock for the present invention. In FIG. 1, stream 1 of H2 and stream 2 of CO2 are combined to form stream 3. The H2 / CO2 ratio is between 2.5 and 4.5 v / v, preferably between 3.0 and 4.0 v / v. The combined feedstock is heated to 1,400° F. by indirect heat exchange. (760℃) It is important that this initial temperature increase be done without using direct combustion of a carbon-containing gas to provide the heat, as using direct combustion of a carbon-containing gas would mean that carbon dioxide is being produced, potentially negating the effects of converting the carbon dioxide into useful fuels and chemicals.

[0019] The mixed hydrogen and carbon dioxide containing feed gas is heated at least partially to 1,400° F. in a preheater unit 4 outside the main reactor vessel. (760℃) Higher than 1,500°F (816℃) Higher than 1,600°F, preferably (871℃) The preheater is electrically heated and the feed gas temperature is increased to 1,400° F. by indirect heat exchange. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃)The gas is heated to a temperature higher than 1000° C. There are many ways that electrical heating of the feed gas can be accomplished. One method is to use an electrically heated radiant furnace. In this embodiment, at least a portion of the feed gas passes through a heating coil in the furnace. In the furnace, the heating coil is surrounded by a radiant electric heating element. In another embodiment of the invention, the gas passes directly over the heating element, whereby the gas is heated by convection heat transfer. Electric heating elements can be made from a number of materials. The most common heating element is a nickel-chromium alloy. These elements can be wound in strips or wires, or cast in a zigzag shape. The elements are typically fixed in an insulated vessel where ceramic fiber is used for insulation. The radiant element can be divided into multiple sections to control the pattern of heating. Multiple coils and multiple sections may be required to provide the energy to generate the heated feed gas. Radiant furnaces require proper design of heating elements and fluid coils to ensure good view factors and good heat transfer. Power usage by radiant furnaces should be as low as possible. Power usage by radiant furnaces is less than 0.5 MWh (megawatt-hours) of power / metric ton (MT) of CO2 in the feed gas, more preferably less than 0.40 MWh / MT of CO2, and even more preferably less than 0.20 MWh / MT of CO2.

[0020] The heated feed gas stream 5 is then fed into the main reactor unit 6. There are two possible embodiments of the main reactor. In the first embodiment, the main reactor is adiabatic or nearly adiabatic and designed to minimize heat loss, but no heat is added to the main reactor, and the temperature in the main reactor decreases from the inlet to the outlet of the reactor. In the second embodiment, the main reactor is designed similarly, but additional heat is added to the vessel to maintain an isothermal or nearly isothermal temperature distribution in the vessel. The main reactor is a tubular reactor with a length greater than its diameter. The inlet to the main reactor is smaller than the overall diameter of the vessel. The main reactor is a steel vessel. The steel vessel is internally insulated to limit heat loss. Various insulation materials may be used to limit heat loss to the environment, including poured or castable refractory lining or insulating bricks. (See Harbison-Walker Handbook of Refractory Practices, 2005, https: / / mha-net.org / docs / Harbison%20Walker%202005%20-Handbook.pdf).

[0021] Inside the main reactor vessel is a bed of catalyst. The catalyst can be in the form of granules, pellets, spheres, trilobes, quadra-lobes, monoliths or any other designed shape to minimize the pressure drop across the reactor. Ideally, the shape and size of the catalyst particles are controlled to ensure that the pressure drop across the reactor is less than 50 pounds per square inch (psi) [345 kPa], more preferably less than 20 psi [139 kPa]. The size of the catalyst form can have a characteristic dimension between 1 mm and 10 mm. The catalyst particles can be as small as 20 mm or less. 2 / g, more preferably 30m 2The catalyst is a porous material with an internal surface area greater than 1000 nm / g. Several catalytic materials are expected to be capable of catalyzing the RWGS reaction. The primary catalysts previously investigated were Cu or Pt or Rh dispersed on metal oxide supports. (Daza & Kuhn, RSC Adv. 2016, 6, 49675-49691). The preferred catalyst is a supported catalyst, which we have found to have high thermal stability up to 1,100°C, no carbon formation (coking), and good tolerance to contaminants present in the captured CO2 stream. The catalyst is highly active even at low metal concentrations, e.g., 0.5-20 wt.%. The catalyst shape and particle size are controlled to provide a pressure drop across the reactor of less than 50 pounds per square inch or less than 20 pounds per square inch.

[0022] The catalyst used in the present method is a versatile, high performance catalyst that efficiently catalyzes the RWGS reaction.

[0023] In the main reactor vessel, the conversion of carbon dioxide to carbon monoxide is typically between 60-90 mol %, more preferably between 70-90 mol %. When an adiabatic reactor embodiment is used, the temperature in the main reactor vessel decreases from the inlet to the outlet. The main reactor outlet temperature is typically 100°C higher than the main reactor inlet temperature. °F(56℃) ~200°F (111℃) and more preferably 105° C. lower than the inlet temperature of the main reactor. °F(58℃) ~160°F (89℃) The gas hourly space velocity (GHSV), calculated by dividing the mass flow rate of the reactants (H2+CO2) per hour by the mass of the catalyst in the bed of the main reactor, is between 1,000 and 60,000 hr -1 More preferably, it is between 10,000 and 30,000 hours. -1 It is.

[0024] The gas exiting the main reactor is the product gas. The product gas includes CO, H2, unreacted CO2, and H2O. Additionally, the product gas may include methane (CH4) produced by side reactions in the main reactor. In one embodiment, the methane production is preferably less than 10%, in another embodiment, less than 5%, and in another embodiment, less than 1%.

[0025] At this point in the process, product gas stream 7 can be used in a variety of ways. It can be cooled, compressed and used in downstream processes to produce fuels and chemicals. It can also be cooled, compressed in unit 8 and sent back to the preheater and fed back to the main reactor. It can also be reheated in a second electric preheater (unit 9) and sent to a second reactor (unit 10) for additional conversion of CO2 to CO. Compression (unit 11) can be used if necessary before sending the CO and H (or syngas) to the liquid fuel synthesis step (stream 12).

[0026] FIG. 4 shows details of a typical arrangement, including an electric gas preheater, a RWGS reactor, and a cross exchanger. and CO2 and The feed gas, which contains a mixture of gases, enters the shell side of a shell-and-tube cross exchanger where it is heated by tubes containing the hot product gas leaving the RWGS reactor. The feed gas is then further heated in an electric gas preheater unit where electrical resistive heating elements raise the temperature of the feed gas to 1,400° F. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃)The heated feed gas then enters the RWGS reactor where the CO2 and H2 react over a packed bed of catalyst to produce carbon monoxide and water. This reaction is endothermic and either causes a temperature drop in the RWGS reactor or requires the addition of an electrical resistive heating element to provide additional heat energy into the RWGS reactor to maintain the temperature. The hot product gas from the outlet of the RWGS reactor then enters the tube side of a cross exchanger where it is cooled by the incoming feed gas.

[0027] Some Reverse Water Gas Shift Process Embodiments

[0028] Below are several embodiments of a method for converting carbon dioxide to product gas using a reverse water gas shift catalytic reactor system.

[0029] 1. Hydrogen and carbon dioxide are mixed and fed into a RWGS catalytic reactor, where the RWGS reactor vessel is adiabatic or nearly adiabatic. The primary reactor vessel is an insulated steel vessel containing a catalyst bed containing a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0030] 2. Hydrogen and carbon dioxide are mixed and fed into the RWGS catalytic reactor where heat is applied to the RWGS reactor vessel to maintain an isothermal or near isothermal temperature distribution within the vessel. Heating is achieved without direct combustion of carbon-containing gases. The primary reactor vessel is an insulated steel vessel containing a catalyst bed comprising a supported catalyst composed of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0031] 3. Hydrogen and carbon dioxide are mixed and sent to a Reverse Water Gas Shift "RWGS" catalytic reactor with a H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v, the RWGS reactor vessel being adiabatic or nearly adiabatic. The main reactor vessel is an insulated steel vessel containing a catalyst bed comprising a supported catalyst composed of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0032] 4. Mix hydrogen and carbon dioxide and feed into a "RWGS" catalytic reactor with a H2 / CO2 ratio between 2.5v / v and 4.5v / v, preferably between 23.0v / v and 4.0v / v, where heat is added to the vessel to maintain an isothermal or near isothermal temperature distribution within the vessel, using a RWGS reactor vessel where the heating is achieved without direct combustion of a carbon-containing gas. The main reactor vessel is an insulated steel vessel containing a catalyst bed comprising a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0033] 5. Hydrogen and carbon dioxide are mixed and the inlet temperature is 1,400°F. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃) and feeds the H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v, into a reverse water gas shift "RWGS" catalytic reactor, where the RWGS reactor is adiabatic or nearly adiabatic. The main reactor is an insulated steel vessel containing a catalyst bed comprising a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor.

[0034] 6. Mix hydrogen and carbon dioxide in a 1,400°F inlet (760℃) to temperatures above 1,500°F (816℃)to temperatures above 1,600°F. (871℃) and feeds the mixture into a reverse water gas shift "RWGS" catalytic reactor with a H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v, where heat is applied to the RWGS vessel to maintain an isothermal or near isothermal temperature profile within the vessel, and heating is achieved without direct combustion of carbon-containing gases. The primary reactor vessel is an insulated steel vessel containing a catalyst bed comprising a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0035] 7. Hydrogen and carbon dioxide are mixed and heated in an electrically heated radiant furnace to an inlet temperature of 1,400°F. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃) and feed H2 / CO2 ratio of between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v, into the RWGS catalytic reactor, where the RWGS reactor is adiabatic or nearly adiabatic. The main reactor is an insulated steel vessel containing a catalyst bed comprising a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor.

[0036] 8. The mixed hydrogen and carbon dioxide are heated in an electrically heated radiant furnace at an inlet temperature of 1,400°F. (760℃) Higher than 1,500°F (816℃)and feed into a reverse water gas shift "RWGS" catalytic reactor with a H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v, where heat is applied to the RWGS reactor vessel to maintain an isothermal or near isothermal temperature profile within the vessel, and heating is achieved without direct combustion of carbon-containing gases. The primary reactor vessel is an insulated steel vessel containing a catalyst bed comprising a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0037] 9. Hydrogen and carbon dioxide are mixed and heated in an electrically heated radiant furnace to an inlet temperature of 1,400°F. (760℃) to temperatures above 1,500°F (816℃) or preferably 1,600° F. (871℃) and feed into a Reverse Water Gas Shift "RWGS" catalytic reactor with a H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, or preferably between 3.0 v / v and 4.0 v / v. The electrical usage by the radiant furnace is less than 0.5 MWh of power / metric ton of CO2, or less than 0.4 MWh of power / metric ton of CO2, or less than 0.2 MWh of power / metric ton of CO2 in the feed gas. The RWGS reactor is insulated and The primary reactor vessel is an insulated steel vessel containing a catalyst bed including a supported catalyst, the catalyst comprising one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas exits the RWGS reactor vessel.

[0038] 10. Hydrogen and carbon dioxide are mixed and heated in an electrically heated radiant furnace to an inlet temperature of 1,400°F. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃)and feeds into the RWGS catalytic reactor with a H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v. The electricity usage by the radiant furnace is less than 0.5 MWh power / metric ton of CO2, or less than 0.4 MWh power / metric ton of CO2, or less than 0.2 MWh power / metric ton of CO2 in the feed gas. The RWGS reactor vessel provides heating without direct combustion of carbon-containing gases, with heat being added to the vessel to maintain an isothermal or near isothermal temperature distribution within the vessel. The primary reactor vessel is an insulated steel vessel containing a catalyst bed comprising a supported catalyst, the catalyst being composed of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor vessel.

[0039] 11. Hydrogen and carbon dioxide are mixed and heated in an electrically heated radiant furnace to an inlet temperature of 1,400°F. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃) and feed into the RWGS catalytic reactor at a ratio of H2 / CO2 between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v. The electricity usage by the radiant furnace is less than 0.5 MWh power / metric ton of CO2, or less than 0.4 MWh power / metric ton of CO2, or less than 0.2 MWh power / metric ton of CO2 in the feed gas. The RWGS reactor is adiabatic or nearly adiabatic. The main reactor is an insulated steel vessel that is tubular (length greater than diameter). The reactor contains a catalyst bed that includes an improved supported catalyst, the catalyst being composed of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor.

[0040] 12. The mixed hydrogen and carbon dioxide are heated in an electrically heated radiant furnace at an inlet temperature of 1,400°F. (760℃) to temperatures above 1,500°F (816℃)to temperatures above 1,600°F. (871℃) and fed into the RWGS catalytic reactor with a H2 / CO2 ratio between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.5 v / v. The electricity usage by the radiant furnace is less than 0.5 MWh power / metric ton of CO2, or less than 0.4 MWh power / metric ton of CO2, or less than 0.2 MWh power / metric ton of CO2 in the feed gas. In the RWGS reactor, heat is applied to the vessel to maintain an isothermal or near isothermal temperature distribution in the vessel, and heating is achieved without direct combustion of carbon-containing gas. The main reactor is an insulated steel vessel, tubular (length greater than diameter). The reactor contains a catalyst bed with a supported catalyst, which is composed of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor.

[0041] 13. Hydrogen and carbon dioxide are mixed and heated in an electrically heated radiant furnace to an inlet temperature of 1,400°F. (760℃) to temperatures above 1,500°F (816℃) to temperatures above 1,600°F. (871℃) and feed into the RWGS catalytic reactor at a ratio of H2 / CO2 between 2.5 v / v and 4.5 v / v, preferably between 3.0 v / v and 4.0 v / v. The electricity usage by the radiant furnace is less than 0.5 MWh power / metric ton of CO2, or less than 0.4 MWh power / metric ton of CO2, or less than 0.2 MWh power / metric ton of CO2 in the feed gas. The RWGS reactor is adiabatic or nearly adiabatic. The main reactor is an insulated steel vessel that is tubular (length greater than diameter). The reactor contains a catalyst bed that includes a supported catalyst, the catalyst consisting of one or more Group 1 and Group 2 metals supported on a metal-alumina spinel. The RWGS product gas leaves the RWGS reactor. EXAMPLES

[0042] Example 1: Process flowsheet produced by an adiabatic primary reactor

[0043] Figure 1 shows the overall process flow for this example. Table 1 shows a summary of the flows for this flowsheet example. Stream No. 1 (CO2) and Stream No. 2 (hydrogen from electrolysis) were mixed and heated at about 70°C. °F(21℃) ~984°F (529℃) Through indirect heat exchange with the feed gas, a heated stream numbered 3 is formed. This is the feed gas stream, and stream 35 is the heated feed gas stream. An electric heater unit 4 heats the feed gas to 984° F. (529℃) From 1,600° F(871℃) The preheater is an electric radiant furnace, using 30.7 MW of power to accomplish the heating. For this example, unit 6 of the main reactor is adiabatic. Stream number 7 is the product gas. The temperature of the product gas is 1,600° F. (871℃) to 144°F (62℃) The CO2 conversion is 70 mol%. The pressure drop across unit 6 of the RWGS reactor is 10 psi.

[0044] In this embodiment, the product gas is heated in the second preheater unit 9 to 1,600° F. (871℃) to form stream 13, which is then reacted in the second reactor, unit 10, to form stream 14. The CO2 conversion in the second reactor is 7%.

[0045] [Table 1]

[0046] The present disclosure includes the following. (1) 1. A process for converting a feed gas comprising carbon dioxide and hydrogen to a product gas comprising carbon monoxide and water, comprising: a. heating the feed gas in a preheater external to the main reactor vessel to an inlet temperature greater than 1,400° F. (760° C.) to produce a heated feed gas; b. the preheater uses electricity to generate heat to produce the heated feed gas; c. directing the heated feed gas into a primary reactor vessel; d. the primary reaction vessel is an insulated or nearly insulated vessel that minimizes heat loss; e. the primary reactor vessel contains a catalyst that converts the heated feed gas into the product gas; f. the method wherein said product gas exits said primary reactor vessel at an outlet temperature, said outlet temperature being less than said inlet temperature. (2) The method described in (1) above, wherein the outlet temperature is at least 50°F (28°C) lower than the inlet temperature. (4) The catalyst does not form carbon and has high thermal stability up to 1,100°C; (3) The method described in. (5) The method according to (1) above, wherein the feed gas also contains methane. (6) The method according to (1) above, further comprising heating the product gas in a second preheater to form a second preheated gas, and supplying the second preheated gas to a second reaction vessel. (7) The method according to (1) above, wherein the product gas is cooled and compressed, and then heated in a second preheater to form a second preheated gas, and the second preheated gas is supplied to the main reaction vessel. (8) The preheater is configured to reduce the amount of CO 2 The method described in (1) above, using less than 0.5 MWh of electricity per unit time. (9) The preheater is configured to reduce the amount of CO 2 The method described in (1) above, using less than 0.4 MWh of electricity per unit time. (10) CO from the heated gas to the product gas 2 The process according to (1) above, wherein the conversion is 60 mol% or more. (11) CO from the heated feed gas to the product gas 2 The process according to (1) above, wherein the conversion is 70 mol% or more. (12) 1. A method for converting a feed gas comprising carbon dioxide and hydrogen into a product gas comprising carbon monoxide and water, comprising: a. heating the feed gas in a preheater external to the main reactor vessel to an inlet temperature greater than 1,500° F. (816° C.) to produce a heated feed gas; b. the preheater uses electricity to generate heat to produce the heated feed gas; c. directing the heated feed gas into a primary reactor vessel; d. maintaining said primary reactor at or near isothermal conditions by supplying electrically generated heat to said primary reactor; e. the primary reactor vessel contains a catalyst that converts the heated feed gas into the product gas; f. The method wherein said product gas exits said primary reactor at an outlet temperature, said outlet temperature being within 5°F (3°C) of said inlet temperature.

Claims

1. 1. A process for converting a feed gas comprising carbon dioxide and hydrogen to a product gas comprising carbon monoxide and water, comprising: a. heating the feed gas in a preheater external to a primary reactor vessel to an inlet temperature greater than 1,400° F. (760° C.) to produce a heated feed gas having a composition with a hydrogen to carbon dioxide ratio (H2 / CO2) between 2.5 (v / v) and 4.5 (v / v); b. the preheater uses electricity to generate heat to produce the heated feed gas; c. directing the heated feed gas into the primary reactor; d. the primary reaction vessel is an insulated or nearly insulated vessel that minimizes heat loss; e. the primary reactor vessel contains a catalyst that converts the heated feed gas into the product gas; f) the product gas exits said primary reactor vessel at an outlet temperature, said outlet temperature being less than said inlet temperature.

2. 10. The method of claim 1, wherein the outlet temperature is at least 50°F (28°C) lower than the inlet temperature.

3. 10. The method of claim 1, wherein the catalyst does not form carbon and has high thermal stability up to 1,100°C.

4. The method of claim 1 , wherein the feed gas also comprises methane.

5. 2. The method of claim 1, further comprising heating the product gas in a second preheater to form a second preheated gas, and supplying the second preheated gas to a second reaction vessel.

6. 2. The method of claim 1, wherein the product gas is cooled and compressed and then heated in a second preheater to form a second preheated gas, and the second preheated gas is supplied to the primary reaction vessel.

7. The preheater reduces the amount of CO in the feed gas by 1 metric ton. ２ 13. The method of claim 1, wherein the method uses less than 0.5 MWh of electricity per

8. The preheater reduces the amount of CO in the feed gas by 1 metric ton. ２ 2. The method of claim 1, wherein the method uses less than 0.4 MWh of power per unit time.

9. CO from the heated gas to the product gas ２ 2. The process of claim 1, wherein the conversion is 60 mol% or more.

10. CO from the heated feed gas to the product gas ２ 2. The process of claim 1, wherein the conversion is 70 mol % or more.

11. 1. A method for converting a feed gas comprising carbon dioxide and hydrogen into a product gas comprising carbon monoxide and water, comprising: a. heating the feed gas to an inlet temperature greater than 1,500° F. (816° C.) in a preheater external to a main reactor vessel to produce a heated feed gas having a composition with a hydrogen to carbon dioxide ratio (H2 / CO2) between 2.5 (v / v) and 4.5 (v / v); b. the preheater uses electricity to generate heat to produce the heated feed gas; c. directing the heated feed gas into the primary reactor; d. maintaining said primary reactor at or near isothermal conditions by supplying electrically generated heat to said primary reactor; e. the primary reactor vessel contains a catalyst that converts the heated feed gas into the product gas; f) the product gas exits said primary reactor vessel at an outlet temperature, said outlet temperature being within 5° F. (3° C.) of said inlet temperature.

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