Systems and methods for producing methanol using carbon dioxide

Abstract

A system and method for producing methanol using synthesis gas, a mixture primarily of hydrogen and carbon monoxide, hydrogen, and carbon dioxide by-product, significantly reducing carbon dioxide emissions and / or sequestration. Syngas can be produced, for example, by an autothermal reactor, steam methane reformer, or gasifier. Hydrogen can be produced by an electrolyzer.

Description

Technical Field

[0001] Related Applications This application claims priority to U.S. Provisional Application No. 63 / 430,210, filed December 5, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety.

[0002] The present disclosure relates to systems and methods for producing methanol using carbon dioxide. More specifically, the systems and methods produce methanol using synthesis gas, which is mainly a mixture of hydrogen and carbon monoxide, hydrogen, and carbon dioxide by-products, and significantly reduce carbon dioxide emissions and / or sequestration.

Background Art

[0003] Conventional methods for producing methanol are based on fossil fuels such as natural gas (NG) and naphtha in steam methane reformers, autothermal reformers, etc. These methods produce carbon dioxide (CO2) and other greenhouse gases that are either released into the atmosphere or must be captured and sequestered.

[0004] Synthesis gas can be produced by steam reforming or partial oxidation of hydrocarbons. In either case, CO2 is a by-product that must be either released into the atmosphere or captured and sequestered. Feedstocks for steam reforming include natural gas, natural gas liquids, and naphtha, which are typically converted by catalytic steam reforming into a crude synthesis gas consisting of hydrogen (H2) and carbon monoxide (CO). The crude synthesis gas is then further processed depending on the desired final product. In the case of pure hydrogen, the process includes features such as catalytic conversion of CO and pressure swing adsorption units, where all impurities are removed in a single step. Feedstocks for partial oxidation are heavy oils, including everything from residual oil to asphalt and coal, which are partially burned with oxygen (O2) by non-catalytic partial oxidation to produce a crude synthesis gas consisting of H2 and CO. The synthesis gas can be further processed to produce methanol or other marketable products.

[0005] Electrolysis is a promising option for producing carbon-free hydrogen from renewable and nuclear sources. Electrolysis uses electricity to split water into H2 and O2. This reaction takes place in units called electrolyzers, which range in size from small, appliance-sized devices well suited for small-scale, distributed hydrogen generation to large, centralized generation facilities that can be directly connected to renewable or other non-greenhouse gas emitting forms of electricity generation.

[0006] The detailed description will now be made with reference to the accompanying drawings, in which like elements are designated with like reference numerals, and in which: [Brief explanation of the drawings]

[0007]

Figure 1

Figure 2

Figure 3

[0008] While the subject matter of this disclosure has been described in particularity, the description itself is not intended to limit the scope of the disclosure. The subject matter may thus be embodied in other ways, including in structures, steps, and / or combinations that are similar to and / or less different from those described herein, in conjunction with other current or future technologies. The term "step" as used herein can describe different elements of the methods used, but this term should not be construed as implying a particular order among the various steps disclosed herein, unless explicitly limited to a particular order by the description. Other features and advantages of the disclosed embodiments will be or become apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. All such additional features and advantages are intended to be included within the scope of the disclosed embodiments. Further, the example figures and dimensions described herein are merely examples and are not intended to claim or imply any limitation with respect to the environments, architectures, designs, or processes in which different embodiments may be implemented. To the extent temperature and pressure are referred to in the following description, these conditions are merely exemplary and are not meant to limit the disclosure. All flows described herein are carried by physical lines.

[0009] The systems and methods disclosed herein integrate conventional processes that produce synthesis gas and H2 for use as feedstock in a methanol reactor, along with CO2 byproduct, to produce methanol, significantly reducing CO2 emissions and / or sequestration. The methanol product can be used as a chemical feedstock or as a fuel.

[0010] In one embodiment, the disclosure includes a system for producing methanol, which includes: i) a methanol reactor for producing a methanol reactor output stream, the methanol reactor including synthesis gas from a synthesis gas stream, hydrogen from a hydrogen stream, and carbon dioxide from a carbon dioxide stream; ii) a separator for separating the methanol reactor output stream into a vapor stream and a liquid stream; and iii) a distillation column for separating the liquid stream into a methanol product stream and a water stream.

[0011] In another embodiment, the present disclosure includes a method for producing methanol, which includes: i) introducing a syngas stream, a hydrogen stream, and a carbon dioxide stream into a methanol reactor to generate a methanol reactor output stream; ii) separating the methanol reactor output stream into a vapor stream and a liquid stream; and iii) separating the liquid stream into a methanol product stream and a water stream.

[0012] Referring to FIG. 1, a schematic illustration of one embodiment of a system 100 for producing methanol using syngas produced by an autothermal reactor 104, H2 produced by an electrolyzer 108, and a combined CO2 stream 120 is shown. A feed stream 102 using NG is supplied to the autothermal reactor 104 along with an O2 stream 106 produced by the electrolyzer 108 and an auxiliary O2 stream 101 from an external source to satisfy the stoichiometry of the required chemical reaction. Through a process called autothermal reforming (ATR), the autothermal reactor 104 produces a syngas stream 110 and a CO2 exhaust stream 112 with a high concentration of post-combustion CO2. The CO2 exhaust stream 112 can be sent to a conventional amine adsorption unit 116 for removal. The amine adsorption unit 116 can include an absorption tower and a desorption / stripping tower that remove CO2 by a chemical absorption process that exposes the CO2 exhaust stream 112 to an aqueous amine solution. The syngas stream 110 is supplied to a conventional methanol reactor 114 along with an H2 stream 118 from the electrolyzer 108 and a combined CO2 stream 120 from the amine adsorption unit 116. Since the conversion of the combined CO2 stream 120 to methanol requires more H2 than that produced with the syngas stream 110, the electrolyzer 108 uses renewable power 121 to convert a desalinated water stream 103 into an H2 stream 118 and an O2 stream 106 to produce the additional H2 required for the conversion.

[0013] The methanol reactor 114 produces a methanol reactor output stream 122 that includes unreacted feed from the feed stream 102, syngas from the syngas stream 110, CO2 from the combined CO2 stream 120, and reaction products including water and methanol. The methanol reactor output stream 122 is sent to a separator 124 where it is cooled and condensed and separated into a liquid stream 126 that includes a mixture of condensed crude methanol and water, and a vapor stream 128 that includes a mixture of unreacted syngas, methane, methanol vapor, CO2, and water vapor. The liquid stream 126 is sent to a distillation column 130 where the condensed crude methanol is separated from the water to produce a purified methanol product stream 132 and a purified water byproduct stream 134 that can be recycled. The vapor stream 128 is sent to a hydrogen separation unit 136 such as a pressure swing adsorption (PSA) unit that produces another H2 stream 138 and a CO2 offgas stream 140 with a high concentration of CO2, which may also contain some syngas and unreacted hydrocarbon feedstock. Another H2 stream 138 can be recycled to the methanol reactor 114, and the CO2 offgas stream 140 can be sent to an amine adsorption unit 116 to remove CO2 by the chemical absorption process described above. Thus, the amine adsorption unit 116 removes CO2 from the CO2 offgas stream 140 and the CO2 discharge stream 112 to produce a combined CO2 stream 120 that is recycled to the methanol reactor 114. Any syngas and unreacted hydrocarbon feedstock in the CO2 offgas stream 140 are removed by the amine adsorption unit 116 as a tail gas stream 142, which can be recycled to the methanol reactor 114 or used as fuel gas.

[0014] Referring to FIG. 2, a schematic view of one embodiment of a system 200 for producing methanol using synthesis gas produced by a steam methane reformer 202, H2 produced by an electrolyzer 108, and a combined CO2 stream 120 is shown. A feed stream 102 using NG or other hydrocarbon (HC) feedstocks (e.g., LPG or naphtha) is fed to a steam methane reformer 202 together with a steam stream 204. Through a process called steam methane reforming (SMR), the steam methane reformer 202 uses a heating furnace with a reforming catalyst inside the reactor tubes and generates a synthesis gas stream 110 and a CO2 exhaust stream 112 with a high concentration of post-combustion CO2 by the heat generated from burning a portion of the feed stream 102 inside the heating furnace. The CO2 exhaust stream 112 can be sent to a conventional amine adsorption unit 116 for CO2 removal. The amine adsorption unit 116 can include an absorption tower and a desorption / stripping tower that remove CO2 by a chemical absorption process that exposes the CO2 exhaust stream 112 to an aqueous amine solution. The synthesis gas stream 110 is fed to a conventional methanol reactor 114 together with an H2 stream 118 from the electrolyzer 108 and a combined CO2 stream 120 from the amine adsorption unit 116. Since the conversion of the combined CO2 stream 120 to methanol requires more H2 than that produced by the synthesis gas stream 110, the electrolyzer 108 generates the additional H2 required for the conversion by converting a demineralized water stream 103 to an H2 stream 118 using renewable power 121.

[0015] The methanol reactor 114 generates a methanol reactor output stream 122 that includes unreacted feed from the feed stream 102, syngas from the syngas stream 110, CO2 from the combined CO2 stream 120, and a reaction product containing water and methanol. The methanol reactor output stream 122 is sent to a separator 124 where it is cooled and condensed and separated into a liquid stream 126 containing a mixture of condensed crude methanol and water and a vapor stream 128 containing a mixture of unreacted syngas, methane, methanol vapor, CO2, and water vapor. The liquid stream 126 is sent to a distillation column 130 where the condensed crude methanol is separated from the water to produce a purified methanol product stream 132 and a purified water byproduct stream 134 that can be recycled. The vapor stream 128 is sent to a hydrogen separation unit 136 such as a pressure swing adsorption (PSA) unit that produces a separate H2 stream 138 and a CO2 offgas stream 140 with a high concentration of CO2, which may also contain some syngas and unreacted hydrocarbon feedstock. The separate H2 stream 138 can be recycled to the methanol reactor 114 and the CO2 offgas stream 140 can be sent to the amine adsorption unit 116 where it can be removed by the chemical absorption process described above. Thus, the amine adsorption unit 116 removes CO2 from the CO2 offgas stream 140 and the CO2 exhaust stream 112 to produce a combined CO2 stream 120 that is recycled to the methanol reactor 114. Any syngas and unreacted hydrocarbon feedstock in the CO2 offgas stream 140 is removed by the amine adsorption unit 116 as a tail gas stream 142, which can be recycled to the methanol reactor 114 or used as fuel gas.

[0016] Referring to FIG. 3, a schematic view of an embodiment of a system 300 for producing methanol using the synthesis gas produced by the gasifier 302, the H2 produced by the electrolyzer 108, and the combined CO2 stream 120 is shown. A feed stream 102 using an HC feedstock (e.g., naphtha, coal, petroleum coke, biomass, and / or solid municipal waste) is supplied to the gasifier 302 together with a steam stream 304, an O2 stream 106 produced by the electrolyzer 108, and an auxiliary O2 stream 101 from an external source to satisfy the stoichiometry of the required chemical reactions. Through a process called gasification, the gasifier 302 produces a synthesis gas stream 110 and a CO2 exhaust stream 112 with a high concentration of post-combustion CO2. The gasifier 302 can include a fluidized bed, a moving bed, a jet system, and / or other conventional components / configurations. The CO2 exhaust stream 112 can be sent to a conventional amine adsorption unit 116 for removal. The amine adsorption unit 116 can include an absorption tower and a desorption / stripping tower that remove CO2 by a chemical absorption process that exposes the CO2 exhaust stream 112 to an aqueous amine solution. The synthesis gas stream 110 is supplied to a conventional methanol reactor 114 together with an H2 stream 118 from the electrolyzer 108 and a combined CO2 stream 120 from the amine adsorption unit 116. Since the conversion of the combined CO2 stream 120 to methanol requires more H2 than that produced by the synthesis gas stream 110, the electrolyzer 108 uses renewable power 121 to convert the desalinated water stream 103 into an H2 stream 118 and an O2 stream 106 to produce the additional H2 required for the conversion.

[0017] The methanol reactor 114 produces a methanol reactor output stream 122 that includes unreacted feed from the feed stream 102, syngas from the syngas stream 110, CO2 from the combined CO2 stream 120, and reaction products including water and methanol. The methanol reactor output stream 122 is sent to a separator 124 where it is cooled and condensed and separated into a liquid stream 126 that includes a mixture of condensed crude methanol and water and a vapor stream 128 that includes a mixture of unreacted syngas, methane, methanol vapor, CO2, and water vapor. The liquid stream 126 is sent to a distillation column 130 where the condensed crude methanol is separated from the water to produce a purified methanol product stream 132 and a purified water byproduct stream 134 that can be recycled. The vapor stream 128 is sent to a hydrogen separation unit 136 such as a pressure swing adsorption (PSA) unit that produces a separate H2 stream 138 and a CO2 offgas stream 140 with a high concentration of CO2 that may also include some syngas and unreacted hydrocarbon feedstock. The separate H2 stream 138 can be recycled to the methane reactor 114 and the CO2 offgas stream 140 can be sent to the amine adsorption unit 116 to remove CO2 by the chemical absorption process described above. Thus, the amine adsorption unit 116 removes CO2 from the CO2 offgas stream 140 and the CO2 exhaust stream 112 to produce a combined CO2 stream 120 that is recycled to the methanol reactor 114. Any syngas and unreacted hydrocarbon feedstock in the CO2 offgas stream 140 are removed by the amine adsorption unit 116 as a tail gas stream 142 that can be recycled to the methanol reactor 114 or used as fuel gas.

[0018] Other variations of the systems and methods described herein can include the production of ammonia using a syngas stream produced in an autothermal reactor where a post-combustion CO2 stream is generated and fed to a dedicated methanol reactor along with an H2 stream (in the appropriate ratio for producing methanol) from an electrolyzer. The O2 stream from the electrolyzer can be fed to the autothermal reactor or used in other O2-consuming processes. For example, other techniques can also be used to separate CO2, such as the use of physical or solid absorbents that can be used in pressure or vacuum swing adsorption processes.

[0019] Although the disclosure has been described in connection with presently preferred embodiments, it will be understood by those skilled in the art that the disclosure of these embodiments is not intended to be limiting. Accordingly, it is contemplated that various alternative embodiments and modifications can be made to the disclosed embodiments without departing from the spirit and scope of the appended claims and their equivalents.

Description of the Reference Numerals

[0020] 100 System 101 Auxiliary O2 Stream 102 Feed Stream 103 Desalinated Water Stream 104 Autothermal Reactor 106 O2 Stream 108 Electrolyzer 110 Syngas Stream 112 CO2 Discharge Stream 114 Methanol Reactor 116 Amine Adsorption Unit 118 H2 Stream 120 Composite CO2 Stream 121 Renewable Power 122 Methanol Reactor Output Stream 124 Separator 126 Liquid Stream 128 Vapor Stream 130 Distillation Column 132 Purified Methanol Product Stream 134 Purified Water By-Product Stream 136 Hydrogen separation unit 138 H2 stream 140 CO2 off-gas stream 142 Tail gas stream 200 System 202 Steam methane reformer 204 Steam stream 300 System 302 Gasifier 304 Steam stream

Claims

1. A methanol reactor for generating a methanol reactor output stream, the methanol reactor comprising synthesis gas from a synthesis gas stream, hydrogen from a hydrogen stream, and carbon dioxide from a carbon dioxide stream, and a separator for separating the methanol reactor output stream into a vapor stream and a liquid stream, and a distillation column for separating the liquid stream into a methanol product stream and a water stream, A system for producing methanol, comprising.

2. A hydrogen separation unit for separating the vapor stream into another hydrogen stream and a carbon dioxide offgas stream, and an amine adsorption unit for generating the carbon dioxide stream and a tail gas stream, the amine adsorption unit comprising carbon dioxide from the carbon dioxide offgas stream and post-combustion carbon dioxide from a carbon dioxide exhaust stream, The system according to claim 1, further comprising.

3. An autothermal reactor for generating the carbon dioxide exhaust stream and the synthesis gas stream, the autothermal reactor comprising natural gas supply from a feed stream and oxygen from an oxygen stream, and an electrolyzer for generating the oxygen stream and the hydrogen stream, the electrolyzer comprising demineralized water from a water stream, The system according to claim 2, further comprising.

4. A steam methane reformer for generating the carbon dioxide exhaust stream and the synthesis gas stream, the steam methane reformer comprising natural gas, naphtha, or liquefied petroleum gas supply from a feed stream and steam from a steam stream, and an electrolyzer for generating the hydrogen stream, the electrolyzer comprising demineralized water from a water stream, The system according to claim 2, further comprising.

5. A gasifier for generating the carbon dioxide exhaust stream and the synthesis gas stream, the gasifier comprising naphtha, coal, petroleum coke, biomass, or solid municipal waste supply from a feed stream, oxygen from an oxygen stream, and steam from a steam stream, and an electrolyzer for generating the oxygen stream and the hydrogen stream, the electrolyzer comprising demineralized water from a water stream, The system according to claim 2, further comprising.

6. The system according to claim 2, wherein the methanol reactor output stream is in direct fluid communication with the separator.

7. The system according to claim 2, wherein the carbon dioxide stream from the amine adsorption unit is in direct fluid communication with the methanol reactor.

8. The system according to claim 2, wherein the vapor stream comprises a mixture of unreacted synthesis gas, methane, methanol vapor, CO2, and water vapor.

9. The system according to claim 2, wherein the liquid stream comprises a mixture of methanol and water.

10. The system according to claim 1, wherein the methanol reactor output stream comprises synthesis gas from the synthesis gas stream, carbon dioxide from the carbon dioxide stream, water, and methanol.

11. A method for producing methanol, comprising: introducing a synthesis gas stream, a hydrogen stream, and a carbon dioxide stream into a methanol reactor to generate a methanol reactor output stream; separating the methanol reactor output stream into a vapor stream and a liquid stream; separating the liquid stream into a methanol product stream and a water stream.

12. The method according to claim 11, wherein the liquid stream is separated into the methanol product stream and the water stream by a distillation column.

13. The method according to claim 11, further comprising separating the vapor stream into another hydrogen stream and a carbon dioxide offgas stream, and generating the carbon dioxide stream and a tail gas stream.

14. The method according to claim 13, wherein the vapor stream is separated into the another hydrogen stream and the carbon dioxide offgas stream by a hydrogen separation unit, and the carbon dioxide stream and the tail gas stream are generated by an amine adsorption unit comprising carbon dioxide from the carbon dioxide offgas stream and post-combustion carbon dioxide from a carbon dioxide discharge stream.

15. The method according to claim 1, wherein the carbon dioxide discharge stream and the synthesis gas stream are generated by an autothermal reactor comprising natural gas supply from a feed stream and oxygen from an oxygen stream, and the oxygen stream and the hydrogen stream are generated by an electrolyzer comprising demineralized water from a water stream.

16. The method according to claim 14, wherein the carbon dioxide discharge stream and the synthesis gas stream are generated by a steam methane reformer comprising natural gas, naphtha, or liquefied petroleum gas supply from a feed stream and steam from a steam stream, and the hydrogen stream is generated by an electrolyzer comprising demineralized water from a water stream.

17. The carbon dioxide exhaust stream and the synthesis gas stream are produced by a gasification device that includes naphtha, coal, petroleum coke, biomass, or solid municipal waste feed from a feed stream, oxygen from an oxygen stream, and steam from a steam stream, and the oxygen stream and the hydrogen stream are produced by an electrolysis device that includes demineralized water from a water stream, the method according to claim 14.

18. The method according to claim 11, wherein the methanol reactor output stream is in direct fluid communication with a separator.

19. The method according to claim 14, wherein the carbon dioxide stream from the amine adsorption unit is in direct fluid communication with the methanol reactor.

20. The method according to claim 11, wherein the methanol reactor output stream includes synthesis gas from the synthesis gas stream, carbon dioxide from the carbon dioxide stream, water, and methanol.

Images