Oxidative dehydrogenation of ethane using carbon dioxide

Abstract

To provide methods and systems suitable for chemical production by dehydrogenation of ethane utilizing carbon dioxide as a soft oxidant.SOLUTION: Ethane and carbon dioxide are reacted in a catalytic reactor so as to produce a reaction product stream comprising at least ethylene and carbon dioxide. The carbon dioxide can be separated for recycling back into the catalytic reactor, and the ethylene can be upgraded using a variety of process units. Heat from the reaction product stream can be recycled for further uses, including reducing the amount of added heating needed in the catalytic reactor. Additional materials, such as carbon monoxide, hydrogen, syngas, methanol, methane, ethane, and even heavier hydrocarbons, can be provided.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure provides chemical production processes. In particular, the present disclosure relates to chemical conversion processes that utilize CO2 as an oxidant. [Background technology]

[0002] Many chemical conversion processes consume very large amounts of energy and can also be a source of various pollutants. For example, known methods for generating ethylene include steam cracking of ethane or naphtha, and such processes are known to consume as much as 1% of the world's energy production. The process also results in significant carbon dioxide emissions. In addition, carbon coking (via the Boudouard reaction) of the catalyst used in the cracking process can result in catalyst deactivation, further increasing the cost of the process. Thus, there remains a need in the art for additional chemical conversion processes. Summary of the Invention

[0003] The present disclosure relates to chemical production processes that utilize ethane (C2H6) as a starting material. For example, the present disclosure may provide for the production of ethylene (C2H4) using ethane as a starting material. The process may reduce the energy requirements of chemical production, prevent catalyst deactivation, consume (instead of produce) carbon dioxide (CO2), and generate other valuable commodity materials, such as hydrogen gas (e.g., via the water-gas shift reaction) and / or methanol (via reverse water-gas shift followed by methanol synthesis).

[0004] In one or more embodiments, the method of the present disclosure may utilize carbon dioxide as a mild oxidant to perform oxidative dehydrogenation of ethane (ODH), thus achieving the production of ethylene through ethane CO2 decomposition. The method may include providing ethane and carbon dioxide into a suitable reactor and utilizing heat provided from a suitable heat source (e.g., concentrated solar energy, combustion, geothermal, or industrial heat source). One or both of the ethane and carbon dioxide may be heated before passing into the reactor, such as by passing through a heat exchanger, which may utilize waste heat recovered from a further stage of the conversion process. The oxidative dehydrogenation of ethane (ODH) in the reactor may result in a number of products, including ethylene, unconverted ethane, carbon dioxide, carbon monoxide (CO), hydrogen (H2), methane (CH4), water (H2O), and possibly trace amounts of heavier hydrocarbons, depending on the catalyst used and the overall reaction conditions.

[0005] Advantageously, reaction conditions can be optimized to drive the reaction to a desired ratio of reaction products. For example, in some embodiments, ethylene, carbon monoxide, and water can be present as primary reaction products. In such embodiments, various separation and conversion techniques can be applied to the reaction products to isolate ethylene and to utilize the remaining reaction products in the formation of further materials, such as methanol. In a preferred embodiment, the ODH reaction can be carried out such that the reaction products include more reaction products. As further described herein, the more complex reaction product mixture can then be further processed to isolate desired goods, recover heat, and recycle chemicals for further reactions.

[0006] In one or more embodiments, the present disclosure may specifically provide a method for chemical production from ethane. In an exemplary embodiment, such a method may include providing ethane and carbon dioxide into a reactor in a molar ratio such that the amount of carbon dioxide provided exceeds the amount stoichiometrically required for complete reaction with ethane, reacting ethane with carbon dioxide in the reactor in the presence of a catalyst to form a reaction product stream comprising at least ethylene and carbon dioxide at a temperature of about 450° C. or higher, passing the reaction product stream through a primary heat exchanger to remove heat therefrom, removing water and optionally any further condensates present in the reaction product stream, compressing the reaction product stream to a pressure of at least 20 bar, separating the carbon dioxide from the reaction product stream in a separation unit to provide an improved ethylene stream, heating at least a portion of the carbon dioxide separated from the reaction product stream using the heat removed from the reaction product stream to form a heated carbon dioxide stream, recycling the heated carbon dioxide stream back into the reactor, and further processing the improved ethylene stream to provide at least ethylene as a produced chemical. In further embodiments, the method may be characterized by one or more of the following statements, which may be combined in any order or number:

[0007] The reactor may be a fixed bed reactor catalytic reactor or a fluidized bed catalytic reactor.

[0008] The reaction product stream may be at a temperature of from about 500°C to about 800°C.

[0009] The reaction product stream may comprise at least 10% by weight carbon dioxide, based on the total weight of the reaction products exiting the reactor.

[0010] The reaction product stream may contain from about 10% to about 60% carbon dioxide by weight, based on the total weight of the reaction products exiting the reactor.

[0011] The primary heat exchanger can be a transfer line exchanger (TLE).

[0012] The reaction product stream exiting the primary heat exchanger may be at a temperature of from about 200°C to about 400°C.

[0013] Removing water, and optionally any further condensate, in the reaction product stream may include passing the reaction product stream through a condensation unit.

[0014] The reaction product stream may be cooled to about ambient temperature in a condensation unit.

[0015] Heating at least a portion of the carbon dioxide separated from the reaction product stream using heat removed from the reaction product stream may include passing the carbon dioxide through a secondary heat exchanger in contact with a circulating stream that is heated in the primary heat exchanger using heat removed from the reaction product stream.

[0016] Recycling the heated carbon dioxide stream back into the reactor may include one or more of the following: injecting the heated carbon dioxide stream directly into the reactor, injecting the heated carbon dioxide stream into a carbon dioxide source, injecting the heated carbon dioxide stream into a line that delivers carbon dioxide from the carbon dioxide source to the reactor, injecting the heated carbon dioxide stream into an ethane source, injecting the heated carbon dioxide stream into a line that delivers ethane from the ethane source to the reactor.

[0017] At least a portion of the heated carbon dioxide stream may be passed through a line heater configured for heat transfer from the heated carbon dioxide stream to one or more streams passed into the reactor.

[0018] A portion of the heat removed from the reaction product stream in the primary heat exchanger may be used to heat one or more of the following: the reactor, the carbon dioxide source, the carbon dioxide line that delivers carbon dioxide from the carbon dioxide source to the reactor, the ethane source, and the ethane line that delivers ethane from the ethane source to the reactor.

[0019] A portion of the heat extracted from the reaction product stream in the primary heat exchanger may be used to heat one or both of a pressurized steam stream and a pressurized CO2 stream for power generation in a closed or semi-open loop power production system in which the working stream is repeatedly compressed and expanded to produce electricity.

[0020] A portion of the heat extracted from the reaction product stream in the primary heat exchanger may be used to heat a steam stream which is injected into the reactor.

[0021] Further processing the improved ethylene stream may include one or more of the following steps: passing the improved ethylene stream through an adsorber to adsorb any water in the improved ethylene stream, passing the improved ethylene stream through a refrigeration unit to cool the improved ethylene stream to a temperature below -50°C, passing the improved ethylene stream through a demethanizer unit, passing the improved ethylene stream through a deethanizer unit, passing the mixture of ethane and ethylene from the deethanizer into a C2 splitter unit.

[0022] The method may include injecting water vapor into the reactor.

[0023] In one or more embodiments, the present disclosure may relate to a system for chemical production from ethane. In an exemplary embodiment, such a system may include a catalytic reactor configured to react ethane with carbon dioxide at a temperature of about 450° C. or greater to form a reaction product stream comprising at least ethylene and carbon dioxide, an ethane line configured for delivery of ethane into the catalytic reactor, a carbon dioxide line configured for delivery of carbon dioxide into the catalytic reactor, a primary heat exchanger configured to receive the reaction product stream from the catalytic reactor and extract heat therefrom, a gas-liquid separation unit configured for removal of water and optionally other condensates from the reaction product stream, a compressor configured for compressing the reaction product to a pressure of at least 20 bar, a carbon dioxide separation unit configured to receive the reaction product stream downstream of the primary heat exchanger and separate at least a portion of the carbon dioxide from the reaction product stream to provide an improved ethylene stream, and a line configured for delivery of at least a portion of the carbon dioxide separated from the reaction product stream in the carbon dioxide separation unit to the reactor while being heated with at least a portion of the heat removed from the reaction product stream in the primary heat exchanger. In further embodiments, the system may be characterized by one or more of the following statements, which statements may be combined in any order or number.

[0024] The system may include a secondary heat exchanger, and a line configured to deliver at least a portion of the carbon dioxide separated from the reaction product stream in the carbon dioxide separation unit to the reactor may pass through the secondary heat exchanger in contact with a line carrying the heated circulation stream from the primary heat exchanger for heating.

[0025] The system may include a line heater configured to heat one or both of the ethane line and the carbon dioxide line.

[0026] The system may include one or more lines configured to deliver a heated flow from the primary heat exchanger to a line heater.

[0027] The system can include one or more lines configured to deliver a heated stream from the primary heat exchanger to one or more of the following: a reactor, a carbon dioxide source, an ethane source, for heat transfer.

[0028] The line configured for delivering at least a portion of the carbon dioxide separated from the reaction product stream in the carbon dioxide separation unit to the reactor may be specifically configured for delivering at least a portion of the carbon dioxide to one or both of the carbon dioxide line and the ethane line.

[0029] The system may include a thermal energy source configured to heat the reactor.

[0030] The thermal energy source may include one or more of the following: concentrated solar energy heaters, combustion heaters, geothermal heaters, and external industrial heat sources.

[0031] The improved ethylene stream may include one or more of the following components configured to receive the improved ethylene stream: a compressor configured for compressing the improved ethylene stream to a pressure of at least 10 bar; an adsorber configured for adsorbing any water in the improved ethylene stream; a refrigeration unit configured to cool the improved ethylene stream to a temperature below -50°C; a demethanizer unit; a deethanizer unit; and a C2 splitter unit. [Brief description of the drawings]

[0032] [Figure 1] 1 is a flow diagram illustrating an exemplary embodiment of a process in which ethane undergoes oxidative dehydrogenation utilizing carbon dioxide as a mild oxidant. [Diagram 2] 1 is a flow diagram illustrating another exemplary embodiment of a process in which ethane undergoes oxidative dehydrogenation utilizing carbon dioxide as a mild oxidant. [Diagram 3] 1 is a flow diagram illustrating yet another exemplary embodiment of a process in which ethane undergoes oxidative dehydrogenation utilizing carbon dioxide as a mild oxidant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The subject matter of the present invention will now be described more fully hereinafter with reference to exemplary embodiments thereof. These exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. Indeed, the subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in this specification and the appended claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise.

[0034] The present disclosure relates to a method for chemical production from ethane. The disclosed method utilizes the oxidative dehydrogenation of ethane by carbon dioxide decomposition. The reaction is preferably catalytic, and various catalysts may be used. For example, in some embodiments, a solid particle heater may be utilized as a reactor, and particles coated with a mixed transition metal catalyst (or similar material) may be heated (e.g., using concentrated solar power) to provide a hybrid thermal catalyst. Such a hybrid thermal catalyst may be useful to facilitate the oxidative dehydrogenation reaction of ethane to ethylene using carbon dioxide as a mild oxidant, as shown below. C2H6+CO2+heat→C2H4+H2O+CO The produced CO may be separated and fully oxidized to drive a turbine. Alternatively, the water gas shift reaction (WGSR) may be used on the produced HO and CO to produce H gas. This would provide the net reaction as shown below: C2H6+heat→C2H4+H2 In such methods utilizing particle flow systems, the catalyst particles may undergo regeneration / cleaning, which may reduce process disturbances. Additionally, the process may be applied to various industrial reactions by utilizing varying catalyst coatings on the particles. The catalyst may be provided as a coating on various elements. For example, in some embodiments, the catalyst may be coated on the interior surface of one or more pipes or tubes such that a catalytic reaction may occur when ethane and carbon dioxide flow through the pipes and contact the catalyst.

[0035] In one or more embodiments, the method for carbon dioxide decomposition of ethane may be carried out as generally described in the process diagram shown in FIG. 1. Specifically, ethane from an ethane source 101 is provided through line 103 and carbon dioxide from a carbon dioxide source 102 is provided through line 104 into reactor 110. Ethane and carbon dioxide may be added separately to reactor 110 or may be combined prior to passing into the reactor. In some embodiments, ethane and / or carbon dioxide in lines 103 and 104, respectively, may be passed through an optional line heater 105, which may be specifically configured for heat transfer to one or more streams passed into the reactor. Reactor 110 may be any suitable type of reactor, such as a fixed bed reactor, catalytic reactor or fluidized bed catalytic reactor containing a suitable catalyst. Additional catalyst may be added to reactor 110 as needed. Thermal energy is provided for the reaction from one or a combination of sources. Recuperative heating may be specifically utilized, as described further herein. Additionally, thermal energy source 112 may supply thermal energy to any one or combination of the following: reactor 110 directly through line 112a, line heater 105 through line 112b, carbon dioxide line 104 through line 112c, carbon dioxide source 102 through line 112d, ethane source 101 through line 112e, ethane line 103 through line 112f. Thermal energy source 112 may be one or a combination of the following thermal energy sources, a concentrated solar energy heat source, a source of combustion heat, an external industrial heat source, or a combination thereof.

[0036] Within reactor 110, oxidative dehydrogenation (ODH) of ethane takes place to provide at least ethylene (and / or other suitable olefins), carbon monoxide, hydrogen, and water. As described further below, additional chemical products may be present in the reaction product stream as well and may be handled according to the present embodiment in combination with further steps as described elsewhere herein. Returning to Figure 1, the reaction product stream exits reactor 110 in line 115 and is passed to ethylene separation unit 120, from which ethylene is removed in line 121. The remaining reaction products, including carbon monoxide, hydrogen, and water, exit in line 122.

[0037] The carbon monoxide, hydrogen, and water mixture in line 122 may be separated into two streams from separator 125. The carbon monoxide, hydrogen, and water mixture in moles (X) is withdrawn in line 130 and cooled in condenser 135 to separate the water via condensation in line 136 and provide purified CO / H2 in line 137. The carbon monoxide, hydrogen, and water mixture in mole fraction (1-X) is withdrawn in line 140 and undergoes a water-gas shift reaction in WGS reactor 145 to provide a mixture of carbon dioxide and hydrogen gas in line 147. The carbon dioxide and hydrogen mixture is separated in separator 155 to provide a recycled carbon dioxide stream in line 157, which may be recycled into one or more of the following: directly, reactor 110, carbon dioxide source 102, carbon dioxide line 104, line heater 105, ethane source 101, ethane line 103. The carbon dioxide in line 157 may be heated utilizing waste heat taken from the reaction products in line 115, for example using an optional recuperative heat exchanger 162. The separator 155 utilized to separate the hydrogen gas from the carbon dioxide may utilize any one or more of the following separation methods: pressure swing adsorption (PSA), membrane separation, cryogenic separation. The resulting hydrogen stream exiting line 159 may be compressed (e.g., to a pressure of at least 20 bar, at least 30 bar, or at least 50 bar, e.g., from about 20 bar to about 150 bar, from about 30 bar to about 125 bar, or from about 50 bar to about 100 bar, particularly about 74 bar) for provision as a commodity or for use in power production. In some embodiments, at least a portion of the hydrogen in line 159 may enter union 165 via line 160 and be combined with at least a portion of the carbon monoxide from line 137 to provide a combined carbon monoxide and hydrogen gas stream in line 166. The combined carbon monoxide and hydrogen gas stream in line 166 may be exported as a synthesis gas product for use in power production. Similarly, at least a portion of the synthesis gas exported from line 166 may be combusted in thermal energy source 112 for heat production. Optionally, at least a portion of the combined carbon monoxide and hydrogen gas stream in line 166 may be provided via line 167 into a synthesis unit 170 for the production of additional chemicals.For example, synthesis unit 170 may include a methanol synthesis unit, where the combined mixture of carbon monoxide and hydrogen gases may be utilized for methanol synthesis. In such case, the produced methanol in line 171 may undergo a dehydration reaction to produce separate streams of ethylene and water.

[0038] A further exemplary embodiment of the method is shown in FIG. 2. As seen therein, into reactor 210, ethane from ethane source 201 is provided through line 203, and carbon dioxide from carbon dioxide source 202 is provided through line 204. Ethane and carbon dioxide may be added separately to reactor 210 or may be combined before passing into the reactor. In some embodiments, ethane and / or carbon dioxide in lines 203 and 204, respectively, may be passed through optional line heater 205, which may be specifically configured for heat transfer to one or more streams passed into the reactor. Reactor 210 again may be any suitable type of reactor, but is preferably a catalytic reactor containing a suitable catalyst (which may be supplemented with additional make-up catalyst as needed). As previously described, thermal energy is provided for the reaction from one or a combination of sources. Specifically, thermal energy source 212 may supply thermal energy to any one or combination of the following: reactor 210 directly through line 212a, line heater 205 through line 212b, carbon dioxide line 204 through line 212c, carbon dioxide source 202 through line 212d, ethane source 201 through line 212e, and ethane line 203 through line 212f.

[0039] In reactor 210, oxidative dehydrogenation (ODH) of ethane takes place to produce at least ethylene (and / or other suitable olefins), carbon monoxide, hydrogen, and water. The reaction product stream exits reactor 210 in line 215 and passes through WGS reactor 245 to provide a mixed stream of carbon monoxide, hydrogen, carbon dioxide, and ethylene in line 247. The mole fractions of carbon monoxide and hydrogen provided in line 247 can be adjusted to various ratios depending on the extent of reaction in WGS reactor 245. The mixed stream of carbon monoxide, hydrogen, carbon dioxide, and ethylene is separated into three streams through separator 225. The first stream formed with recycled carbon dioxide is recycled through stream 257 into one or more of the following: directly into reactor 210, carbon dioxide source 202, carbon dioxide line 204, line heater 205, ethane source 201, ethane line 203. The carbon dioxide in line 257 may be heated utilizing waste heat taken from the reaction products in line 215, for example using optional recuperative heat exchanger 262. A second stream formed with ethylene exits in line 221. A third stream comprising a mixture of carbon monoxide, hydrogen, and carbon dioxide exits in line 267 and may be processed for the production of additional chemicals. For example, at least a portion of the mixture of carbon monoxide, hydrogen, and carbon dioxide may pass through line 268 into a methanol synthesis unit 270 to produce methanol in line 271, which may undergo a dehydration reaction to produce separate streams of ethylene and water.

[0040] In one or more embodiments, the method of the present disclosure may be particularly useful when the amount of carbon dioxide utilized in the cracking process is advantageously increased beyond the amount required, such that the reaction stream contains excess carbon dioxide. This may include providing ethane and carbon dioxide into the reactor in a molar ratio such that the amount of carbon dioxide provided exceeds the amount stoichiometrically required for complete reaction with ethane. The molar excess of carbon dioxide may be sufficient such that the reaction product exiting the reactor may contain at least 5%, at least 10%, at least 20%, at least 25%, at least 30%, or at least 40% carbon dioxide, specifically up to about 80% by weight, based on the total weight of the reaction product exiting the reactor. In preferred embodiments, the reaction product exiting the reactor may contain from about 5% to about 70%, from about 10% to about 60%, or from about 20% to about 50% by weight carbon dioxide, based on the total weight of the reaction product exiting the reactor. The presence of excess carbon dioxide is advantageous for several reasons. For example, providing excess carbon dioxide can ensure that maximum ethane conversion occurs in the reactor. It can also provide a large mass of recyclable material that can reduce the amount of make-up carbon dioxide that may be replenished in the reactor. It can also provide a large amount of heat that can be recovered to reduce the amount of energy that must be expended for heating in the reactor.

[0041] The advantages of utilizing excess carbon dioxide in the reaction are further described in connection with FIG. 3. As seen therein, into reactor 310, ethane from ethane source 301 is provided through line 303, and carbon dioxide from carbon dioxide source 302 is provided through line 304. Ethane and carbon dioxide may be added separately to reactor 310 or may be combined prior to passing into the reactor. In some embodiments, ethane and / or carbon dioxide in lines 303 and 304, respectively, may be passed through optional line heater 305, which may be specifically configured for heat transfer to one or more streams passed into the reactor. Reactor 310 again may be any suitable type of reactor, but is preferably a catalytic reactor containing a suitable catalyst (which may be supplemented with additional make-up catalyst as necessary). As previously described, thermal energy is provided for the reaction from one or a combination of sources. Specifically, thermal energy source 312 may supply thermal energy to any one or combination of the following: reactor 310 directly through line 312a, line heater 305 through line 312b, carbon dioxide line 304 through line 312c, carbon dioxide source 302 through line 312d, ethane source 301 through line 312e, and ethane line 303 through line 312f. In certain embodiments, both ethane in line 303 and carbon dioxide in line 304 are preheated in line heater 305 before being sent to reactor 310. While such heating alone may be sufficient to provide the desired reaction temperature in reactor 301, additional heating may be provided directly to the reactor. In some embodiments, a steam flow may be provided in line 312a to deliver thermal energy from thermal energy source 312. Alternatively, the steam flow may be provided in addition to the thermal energy from the thermal energy source.

[0042] The reaction in the reactor is preferably carried out at a temperature of at least 450° C., at least 475° C., or at least 500° C., up to about 1000° C., etc. In a preferred embodiment, the temperature in the reactor 310 for the reaction to occur ranges from about 450° C. to about 1000° C., from about 500° C. to about 800° C., or from about 550° C. to about 700° C. Such temperatures may further apply to other embodiments described herein. The reaction of ethane and carbon dioxide in the reactor produces a reaction product stream that includes at least ethylene, carbon monoxide, water, and carbon dioxide, but may also include unreacted ethane, hydrogen, methane, and trace amounts of heavier hydrocarbons. The reaction product mixture exits the reactor 310 in line 315 and is passed into a heat exchanger 362. The heat exchanger 362 may be referred to as a primary heat exchanger 362 for ease of identification. In an exemplary embodiment, the heat exchanger 362 may be a transfer line exchanger (TLE). Upon passing through the TLE, the reaction products are rapidly cooled to a temperature of about 200° C. to about 400° C., which is advantageous in substantially preventing further side reactions from occurring and thus reducing or eliminating the production of undesirable by-products. Waste heat (Q) removed from the reaction product stream may be utilized for multiple purposes. For example, the waste heat may be utilized to preheat the reactor feed stream. Thus, the heat provided through one or more of streams 312a-312f may be heat provided from heat exchanger 362. In this manner, the heat removed from the reaction product stream may be used to heat the ethane stream and / or the carbon dioxide stream. Similarly, the heat removed from the reaction product stream may be used to directly provide heat to reactor 310. As shown in FIG. 3, a first quantity of heat (Q1) is removed from heat exchanger 362 and used to provide heat to any of reactor 310, ethane source 301, ethane line 303, carbon dioxide source 302, and carbon dioxide line 304. In a further embodiment, as shown in FIG. 3, the waste heat (Q2) from heat exchanger 362 may be used to heat high pressure steam and / or high pressure CO2 streams for power generation in a closed loop or semi-open loop power production system where a working stream is repeatedly compressed and expanded to produce power.Thus, the method of the present disclosure may be reliably combined with any system and method known for power production, particularly those known for generating CO2. For example, U.S. Patent No. 8,596,075, U.S. Patent No. 8,776,532, U.S. Patent No. 8,959,887, U.S. Patent No. 8,986,002, U.S. Patent No. 9,068,743, U.S. Patent No. 9,416,728, U.S. Patent No. 9,546,814, U.S. Patent No. 10,018,115, and U.S. Patent Application Publication No. 2012 / 0067054, the disclosures of which are incorporated herein by reference, all describe systems and methods that may be combined with the method of the present disclosure. Such systems and methods may be a reliable source of CO2 for chemical conversion processes. Similarly, waste heat from the heat exchanger 362 may be used to provide additional heating to such systems and methods.

[0043] After the reaction product stream is cooled in heat exchanger 362, it may enter via line 317 into a gas-liquid separator 335, such as a water separator tower or other condensation unit, to further cool the reaction product stream to about ambient temperature and remove water and other condensates using quench water or oil. As shown in FIG. 3, water and any entrained condensates are removed via stream 336.

[0044] The reaction product stream may undergo various process steps by passing through one or more system units to improve the ethylene concentration in the reaction product stream. Thus, an improved ethylene stream may be defined as a stream that contains a higher weight percent of ethylene than the stream from which it originates. This may be accomplished through the removal of one or more other components from the reaction product stream, such as, for example, carbon dioxide, hydrogen sulfide, and other acid gases. In some embodiments, the enriched or improved ethylene stream may be referred to as a purified reaction product stream, since it still contains at least a portion of the reaction products (e.g., ethylene) and is free of at least a portion of the non-ethylene components (e.g., carbon dioxide, water, etc.).

[0045] The reaction product stream is preferably compressed to enhance separation of further components of the reaction product stream, for example through the use of absorbents, adsorbents, and / or membrane separation. High pressure operation of downstream units, such as carbon dioxide separator 355, can also be useful in reducing the size of equipment and therefore the required capital costs.

[0046] The quenched reaction product stream in line 337 may be compressed to a pressure of at least 20 bar, at least 25 bar, or at least 30 bar (e.g., up to about 100 bar), preferably to a pressure of about 10 bar to about 100 bar, about 20 bar to about 90 bar, or about 30 bar to about 80 bar. As shown in Figure 3, compression is performed using a multi-stage intercooled centrifugal compressor 361, although any alternative compressor suitable to provide the required compression may be used. Optionally, a caustic soda wash may be applied at the outlet of each compression stage to remove traces of acid gases from the process stream.

[0047] The quenched and compressed reaction product stream in line 359 may be directed to carbon dioxide separator 355 where carbon dioxide is separated from the reaction product stream to form a first ethylene-enriched stream in line 364 and a recycled carbon dioxide stream in line 357. The first ethylene-enriched stream in line 364 may be considered an improved ethylene stream because the ethylene weight percent of the stream in line 364 is higher than the ethylene weight percent of the quenched reaction product stream in line 337 and / or the compressed reaction product stream in line 359. The recycled carbon dioxide in stream 357 may be heated using waste heat (Q3) from heat exchanger 362. It is understood that in any or all cases where waste heat is utilized, the stream to be heated may pass through heat exchanger 362 or a secondary circulating heating fluid may be circulated through the heat exchanger for heat transfer to additional streams to be heated. Thus, one or more additional heat exchangers may be utilized to transfer heat from the circulating fluid to the stream in a given line without entrainment of the streams. As shown in FIG. 3, the recycled carbon dioxide in stream 357 may be heated with waste heat (Q3) by passing through secondary heat exchanger 363. In an exemplary embodiment, the circulating fluid may be circulated through primary heat exchanger 362 and secondary heat exchanger 363 such that the carbon dioxide in line 357 is heated using heat removed from the reaction product stream in primary heat exchanger 362. Although not shown in FIG. 3, it is understood that line (Q3) would return from secondary heat exchanger 363 into primary heat exchanger 362 for further removal of heat from the reaction product stream. The recycled carbon dioxide in stream 357 heated with waste heat (Q3) may be combined with any one or more of the following to provide heating: reactor 310, carbon dioxide source 302, carbon dioxide line 304, line heater 305, ethane source 301, ethane line 303. In this manner, the recycled carbon dioxide may be recycled back for dehydrogenation reaction with fresh ethane, reducing the amount of additional carbon dioxide that must be added to the reaction.

[0048] The carbon dioxide separator 355 may be configured to utilize a variety of unit operations, such as an absorption tower, an adsorption bed, a membrane-based separator, a refrigeration process, or any combination thereof. Carbon dioxide separation is preferably performed prior to downstream separation of hydrocarbons and other species in the reaction product stream, because such separation typically involves refrigeration and cooling of the process gases to temperatures above the triple point of carbon dioxide, and cooling the carbon dioxide to such temperatures causes sublimation and formation of solid carbon dioxide in the piping and equipment.

[0049] Although carbon dioxide separator 355 is shown downstream of compressor 361, in some embodiments, carbon dioxide separation may be performed between compression states. Thus, the reaction product stream in line 337 may first pass through first stage compressor 361a, then carbon dioxide separator 355, and then second stage compressor 361b. Carbon dioxide separator 355 may be located, for example, between intercooler 361c and second stage compressor 361b. In further embodiments, carbon dioxide separator 355 may be configured to be completely upstream of compressor 361. Thus, substantially no compression may be performed prior to carbon dioxide separation. In further embodiments, however, an auxiliary compressor may be provided downstream of the gas-liquid separator 335 to compress the reaction product stream to a first pressure at which carbon dioxide separation is performed (e.g., up to about 15 bar, from about 5 bar to about 15 bar, etc.), and the reaction product stream exiting the carbon dioxide separator may be passed through compressor 361 to be compressed to a second, higher pressure.

[0050] The compressed first ethylene enriched stream exits carbon dioxide separator 355 in line 364 and is passed to adsorber 375, which may include an adsorbent bed of a suitable material, such as a molecular sieve. The material utilized in adsorber 375 is preferably configured to remove trace amounts of moisture that may otherwise freeze to form ice in downstream piping and equipment operated below the freezing point of water.

[0051] The dried and pressurized first ethylene enriched stream leaving the adsorber in line 376 is then fed into refrigeration unit 377 where it is cooled to a temperature below -50°C, below -100°C, or below -150°C, preferably in the temperature range of about -50°C to about -200°C, about -100°C to about -190°C, or about -150°C to about -180°C, specifically to a temperature of about -165°C. The dried and pressurized first ethylene enriched stream is preferably at a temperature and pressure such that the hydrogen and carbon monoxide present in the stream remain in the vapor phase, while other components of the first ethylene enriched stream are liquefied and can be separated therefrom. Thus, refrigeration unit 377 may include a phase separator.

[0052] Exiting the refrigeration unit in stream 340 is a mixture of carbon monoxide and hydrogen that can be used for chemical production as already described above. For example, the mixture of carbon monoxide and hydrogen in stream 340 can be passed to a WGS reactor 345 to provide a mixed stream of carbon monoxide and hydrogen that can be used for downstream chemical production, such as methanol and / or Fischer-Tropsch (FT) synthesis. The ratio of carbon monoxide and hydrogen can be optionally adjusted in the water gas shift step to meet chemical production requirements.

[0053] A second ethylene-enriched stream exits refrigeration unit 377 in line 379 and is fed to demethanizer unit 380 for separation of any methane therefrom. In addition to the above discussion, the second ethylene-enriched stream in line 379 may be considered an improved ethylene stream because it contains a higher weight percent of ethylene compared to the immediately upstream stream in line 376 that is passed through refrigeration unit 377. A methane-rich stream exits demethanizer unit 380 in line 381. The methane-rich stream may be exported as a commodity. In some embodiments, at least a portion of the methane may be removed in line 382 for use in reactor 310 to provide reaction heating and / or for use in thermal energy source 312 to provide combustion heating.

[0054] A third ethylene enriched stream (which may also be considered a refined ethylene stream) also exits the demethanizer unit 380 in line 385 and is fed to a demethanizer column 387. A bottoms product comprised of C3 and larger hydrocarbons is withdrawn in line 389. In some embodiments, methane and other light gases from the top of the demethanizer column unit may be used as a supplemental fuel for the reactor 310 and / or thermal energy source 312. In further embodiments, unconverted ethane from the C2 splitter may be used as a supplemental fuel for the reactor 310 and / or thermal energy source 312.

[0055] The fourth ethylene enriched stream (containing primarily ethylene and ethane) passes via line 391 into C2 splitter column 392 to further split the stream into its primary components ethylene and ethane. An overhead ethane stream in line 393 from C2 splitter column 392 is recycled back to dehydrogenation reactor 310. A purified ethylene stream exits the bottom of C2 splitter column 392 in line 395. Separation and purification of the heavier hydrocarbons in the stream from the bottom of deethanizer unit 387 may be performed in any suitable combination, such as a depropanizer / C3 splitter, debutanizer / C4 splitter, etc.

[0056] As can be seen from the foregoing, the present disclosure provides a sustainable and environmentally friendly method for the production of ethylene, H2, and methanol, the three most fundamental components of the chemical industry globally. Ethylene is the most produced organic compound on earth and is known to be used in numerous products. The disclosed method may allow for the production of ethylene using less energy industrially while also producing H2, methanol, and additional chemical products as well. Furthermore, the disclosed method also consumes CO2 by essentially "fixing" it into a compound that does not re-emit the CO2 upon end use.

[0057] Many modifications and other embodiments of the subject matter of the present disclosure will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing description and the accompanying drawings. It is to be understood, therefore, that the present disclosure is not limited to the specific embodiments described herein, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed in the specification, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. 1. A method for chemical production, the method comprising: providing a hydrocarbon and carbon dioxide into a reactor in a molar ratio such that the amount of carbon dioxide provided exceeds the amount stoichiometrically required for complete reaction with the hydrocarbon; reacting the hydrocarbon with the carbon dioxide in the reactor in the presence of a catalyst to form a reaction product stream comprising olefins, water, and carbon dioxide; passing said reaction product stream through a primary heat exchanger to remove heat therefrom; removing water and optionally any further condensate present in said reaction product stream; compressing the reaction product stream to a pressure of at least 20 bar; separating carbon dioxide from said reaction product stream in a separation unit to provide a refined stream comprising said olefins; A method comprising:

2. heating at least a portion of the carbon dioxide separated from the reaction product stream using heat removed from the reaction product stream to form a heated carbon dioxide stream; recycling the heated carbon dioxide stream back into the reactor; and The method of claim 1 further comprising:

3. recycling the heated carbon dioxide stream back into the reactor injecting said heated carbon dioxide stream directly into said reactor; injecting said heated carbon dioxide stream into a carbon dioxide source; injecting the heated carbon dioxide stream into a carbon dioxide line delivering carbon dioxide from a carbon dioxide source to the reactor; injecting said heated carbon dioxide stream into said hydrocarbon source; and injecting said heated carbon dioxide stream into a hydrocarbon line delivering said hydrocarbon from said source to said reactor; The method of claim 2 , comprising one or more of:

4. 3. The method of claim 2, wherein at least a portion of the heated carbon dioxide stream is passed through a line heater configured for heat transfer from the heated carbon dioxide stream to one or more streams passed into the reactor.

5. 10. The method of claim 1, wherein the reactor is a fixed bed reactor catalytic reactor or a fluidized bed reactor catalytic reactor.

6. The method of claim 1 , wherein the reaction product stream is at a temperature between 500° C. and 800° C.

7. 10. The method of claim 1, wherein the reaction product stream comprises 10 to 60 weight percent carbon dioxide, based on the total weight of reaction product exiting the reactor.

8. The method of claim 1 , wherein the primary heat exchanger is a transfer line exchanger (TLE).

9. 10. The method of claim 1, wherein the reaction product stream exiting the primary heat exchanger is at a temperature of from 200°C to 400°C.

10. 10. The method of claim 1, wherein removing water and optionally any further condensate present in the reaction product comprises passing the reaction product stream through a condensation unit.

11. 2. The method of claim 1 , wherein heating at least a portion of the carbon dioxide separated from the reaction product stream using heat removed from the reaction product stream comprises passing carbon dioxide through a secondary heat exchanger in contact with a circulating stream that is heated in the primary heat exchanger using heat removed from the reaction product stream.

12. A portion of the heat removed from the reaction product stream in the primary heat exchanger is The reactor, carbon dioxide source, a carbon dioxide line delivering carbon dioxide from the carbon dioxide source to the reactor; a source of said hydrocarbon; and a hydrocarbon line delivering said hydrocarbon from said hydrocarbon source to said reactor; The method of claim 1 , wherein one or more of the following is used to heat the material:

13. A portion of the heat extracted from the reaction product stream in the primary heat exchanger is used to generate pressurized steam and pressurized CO for power generation in a closed or semi-open loop power production system in which a working stream is repeatedly compressed and expanded to produce power. ２ The method of claim 1 , wherein one or both of the streams are used to heat.

14. 10. The method of claim 1, wherein a portion of the heat removed from the reaction product stream in the primary heat exchanger is used to heat a steam stream injected into the reactor.

15. The method further comprises treating the olefin-containing refinery stream to provide at least one chemical product, the treating comprising: passing the olefins-containing refinery stream through an adsorber to adsorb any water in the olefins-containing refinery stream; passing the olefins-containing refinery stream through a refrigeration unit to cool the olefins-containing refinery stream to a temperature below −50° C.; passing said olefin-containing refined stream through a demethanizer unit; and passing said olefin-containing refined stream into a deethanizer unit. The method of claim 1 , comprising one or more of:

16. The method of claim 1 comprising injecting steam into the reactor.

17. The method of claim 1 , wherein the hydrocarbon comprises one or more of ethane, propane, and butane.

18. 1. A system for chemical production, comprising: a catalytic reactor configured to react a hydrocarbon with carbon dioxide at a temperature of 450° C. or greater to form a reaction product stream comprising at least carbon dioxide and olefins; a hydrocarbon line configured for delivery of the hydrocarbon into the catalytic reactor; a carbon dioxide line configured for delivery of carbon dioxide into the catalytic reactor; a primary heat exchanger configured to receive the reaction product stream from the catalytic reactor and extract heat therefrom; a gas-liquid separation unit configured for removal of water and optionally other condensates from said reaction product stream; a compressor configured to compress the reaction product stream to a pressure of at least 20 bar; a carbon dioxide separation unit configured to receive the reaction product stream after at least one stage of compression and separate at least a portion of the carbon dioxide from the reaction product stream to provide a refined stream comprising the at least one olefin; a line configured to deliver at least a portion of the carbon dioxide separated from the reaction product stream in the carbon dioxide separation unit to the reactor while being heated with at least a portion of the heat removed from the reaction product stream in the primary heat exchanger; Including, the system.

19. 20. The system of claim 18, wherein the system includes a secondary heat exchanger, and the line configured to deliver at least a portion of the carbon dioxide separated from the reaction product stream in the carbon dioxide separation unit to the reactor passes through the secondary heat exchanger in contact with a line carrying the heated circulating stream from the primary heat exchanger for heating.

20. 20. The system of claim 18, including a line heater configured to heat one or both of a hydrocarbon line configured for delivery of the hydrocarbon and a carbon dioxide line configured for delivery of the carbon dioxide, and including one or more lines configured to deliver a heated flow from the primary heat exchanger to the line heater.

21. For heat transfer, from the primary heat exchanger: The reactor, a source of carbon dioxide, and The source of said hydrocarbon 20. The system of claim 18, comprising one or more lines configured to deliver a heated flow to one or more of:

22. 20. The system of claim 18, wherein the system includes a thermal energy source configured to heat the reactor, the thermal energy source including one or more of a concentrated solar energy heater, a combustion heater, and an external industrial heat source.

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