Patent Publication Number: US-2021179526-A1

Title: Electrochemical Reduction of Carbon Dioxide to Upgrade Hydrocarbon Feedstocks

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a divisional of and claims priority to U.S. patent application Ser. No. 16/786,858 filed Feb. 10, 2020, which in turn claims priority from Greek patent application number 20190100550 filed Dec. 6, 2019, the entire disclosures of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to the electrochemical reduction of carbon dioxide to produce oxide anions for upgrading feedstocks. 
     BACKGROUND 
     Carbon dioxide (CO 2 ) is the primary greenhouse gas emitted through human activities. Carbon dioxide may be generated in various industrial and chemical plant facilities. At such facilities, the utilization of CO 2  as a feedstock may reduce CO 2  emissions at the facility and therefore decrease the CO 2  footprint of the facility. The conversion of the greenhouse gas CO 2  into value-added products may be beneficial. 
     SUMMARY 
     An aspect relates to a method of operating a system having a solid oxide electrolysis cell (SOEC). The method includes feeding carbon dioxide and an olefin to the SOEC, modulating the amount of the olefin fed to the SOEC, and discharging carbon monoxide and an olefin oxide from the SOEC, wherein the olefin oxide corresponds to the olefin. 
     Another aspect relates to a method of operating a system having an SOEC. The method includes receiving electric current at a cathode of the SOEC and electrochemically reducing carbon dioxide at the cathode via electrons of the electric current to generate carbon monoxide and oxygen ions. The method includes diffusing the oxygen ions through a solid electrolyte including a solid oxide to an anode of the SOEC and oxidizing an olefin at the anode via the oxygen ions into an olefin oxide. 
     Yet another aspect relates a system having an SOEC to receive carbon dioxide and an olefin and discharge carbon monoxide and an olefin oxide. The system includes a conduit to supply the olefin to the SOEC. A control valve is disposed along the conduit to modulate an amount of the olefin supplied to the SOEC. The system includes a second conduit to supply the carbon dioxide to the SOEC. 
     Yet another aspect relates to an SOEC system including an SOEC. The SOEC includes a cathode to electrochemically reduce carbon dioxide into carbon monoxide and oxygen ions and discharge the oxygen ions into a solid electrolyte of the SOEC. The SOEC includes an anode to receive the oxygen ions via the solid electrolyte from the cathode and oxidize an olefin with the oxygen ions into an olefin oxide corresponding to the olefin. The SOEC system includes a feed conduit to supply the carbon dioxide to a cathode side of the SOEC. The cathode side includes the cathode. The SOEC system includes a second feed conduit to supply the olefin to an anode side of the SOEC. The anode side includes the anode. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram of a system having a solid oxide electrolysis cell (SOEC). 
         FIG. 2  is a diagram of a catalytic reactor. 
         FIG. 3  is a block flow diagram of a method of operating a system having an SOEC. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to the electrochemical reduction of carbon dioxide (CO 2 ) to produce oxide anions for upgrading feedstocks including low-value feedstocks. For instance, embodiments relate to the electrochemical reduction of CO 2  to produce oxide anions for upgrading olefin feedstocks. Some aspects are directed to the electrochemical reduction of CO 2  to produce oxide anions to oxidize an olefin into an olefin oxide. The olefin oxide may be utilized as a precursor (or to generate precursors) for the production of higher value hydrocarbons. The present techniques may upgrade olefins (typically a commodity chemical) to more value-added hydrocarbon products. 
     As indicated, embodiments of the present techniques involve electrochemical reduction of CO 2 . Carbon monoxide (CO) and an olefin oxide are electrocatalytically produced. The olefin oxide may be, for example, ethylene oxide, acidcyclohexene, propylene oxide, and so on. The olefin oxide may be subsequently catalytically converted into hydrocarbons (e.g., high-value hydrocarbons). 
     The techniques may electrochemically reduce CO 2  (at a cathode) to provide oxygen ions for oxidation of olefin (at the anode) into the olefin oxide. Therefore, the production of the olefin oxide involves CO 2 . Embodiments may include electrochemically reducing CO 2  at the cathode to provide oxygen ions to diffuse to the anode for oxidation at the anode of the olefin into the olefin oxide. 
     Solid oxide electrolysis cells (SOECs) may be utilized for the electrochemical reduction of the CO 2  and production of the olefin oxide. On the cathode, CO 2  is reduced to CO and oxygen ion species (O 2− ). The O 2−  is diffused via the solid electrolyte to the anode side. The solid electrolyte may be yttria-stabilized zirconia (YSZ), cerium (IV) oxide (CeO 2 ), or other materials that conduct oxygen ions. An olefin is fed to the anode side and partially oxidized by the diffused oxygen ions on the anode to form olefin oxide (C x H 2x O). The generated CO and C x H 2x O may be fed to catalytic reactor(s) to produce high-value hydrocarbons, such as acrylic acid, alcohols, ethers, esters, etc. 
     In the desire to utilize CO 2  as a renewable one-carbon (C1) building block in organic synthesis, attempts have been made to synthesize ethylene oxide by reacting ethylene and CO 2 . However, thermodynamic restrictions of such a reaction may be problematic. 
     While acrylic acid has been primarily produced from propylene via two stage oxidation, a benefit of ethylene oxide production is that ethylene oxide may be a precursor (or utilized to generate a precursor) for the production of acrylic acid. The reliance on ethylene to generate ethylene oxide to produce acrylic acid may reduce the production cost of acrylic acid. The reliance on ethylene instead of propylene to produce acrylic acid may reduce production cost, especially when ethylene is in abundant supply. Certain embodiments herein may convert ethylene into ethylene oxide by the electrochemical reduction of the CO 2 . The ethylene oxide can then be utilized to produce acrylic acid or other hydrocarbon. 
     As discussed for present embodiments, hydrocarbons are produced through the electrochemical reduction of CO 2 . First, the CO 2  and an olefin are fed to an SOEC to produce olefin oxide. Second, the produced olefin oxide may be fed to a catalytic reactor(s) to produce hydrocarbon(s) from the olefin oxide. 
     For the generation of an olefin oxide, gaseous CO 2  is fed into the cathode side of the SOEC to produce CO and O 2−  ions. These O 2−  ions diffuse through the solid electrolyte (e.g., ultra-stabilized zirconia or other material that can conduct O 2−  ions) to reach the anode side of the SOEC. An olefin (C x H 2x ) is fed to the anode side to release an electron (per olefin molecule) and form the corresponding olefin oxide (C x H 2x O). 
     In certain embodiments, the CO 2  stream fed to the SOEC cathode side may be primarily CO 2 , such as greater than 50 weight percent (wt %) CO 2 , greater than 80 wt % CO 2 , or greater than 90 wt % CO 2 . In other embodiments, the CO 2  may be a component at less than 50 wt % of the stream fed to the cathode side of the SOEC. 
     In some embodiments, the stream fed the cathode side may include both CO 2  and water (H 2 O). The H 2 O may also be subjected to electrochemical reduction at the SOEC cathode to generate O 2−  ions that migrate to the anode side. In particular implementations, the stream supplied to the SOEC cathode side may be a flue gas having CO 2  and H 2 O, and additional compounds. 
     An SOEC typically has the same or similar components (e.g., cathode, anode, and electrolyte) as a solid oxide fuel cell (SOFC) but generally operates reversibly in comparison to the SOFC. An SOFC generates electricity. In contrast, an SOEC relies on an electron source (external source of electricity). The heat and electricity to operate the SOEC may be produced from renewable sources, such as solar, wind, geothermal, or hydropower. Heat may be added to the SOEC to maintain a desired operating temperature of the SOEC including the electrochemical reduction. Heat may be add to the SOEC, for example, by resistive heating (e.g., at the SOEC electrodes), a steam jacket, solar heating systems, etc. In implementations, the CO 2  electrolysis by the SOEC may be at a temperature in a range of 700° C. to 900° C. and at atmospheric pressure. The material of the SOEC electrodes (cathode and anode) may be based on ceramic materials that exhibit stability through reduction-oxidation (redox) cycles, electrocatalytic activity, and mixed ionic and electronic conductivity in reducing atmospheres. The material of the SOEC electrodes may be metal or metal oxides based material (e.g., Ni-based electrodes). 
       FIG. 1  is a system  100  to electrochemically reduce CO 2  to give oxygen ions to oxidize olefin  102  into olefin oxide  104 . The system  100  includes an SOEC  106  having two electrodes including a cathode  108  and an anode  110 . The cathode side  112  includes the cathode  108  in a cathode-side cavity  114 . The anode side  116  includes the anode  110  in an anode-side cavity  118 . A solid electrolyte  120  is disposed between the cathode  108  and the anode  110 . 
     A power source  122  supplies electric current (electrons) to the cathode  108  for the electrochemical reduction of CO 2  into CO to occur. The power source  122  may be a battery, a power generator, an electrical grid, a renewable source of power, etc. The applied electric current may be modulated or regulated. The desired amount of current (or set point of the amount of current supplied) may be determine correlative with reaction requirements at the cathode  108  or anode  110 . In implementations, the amount of current input may be based at least in part on the oxidation reaction requirement at the anode  110 . The amount of current supplied by the power source  122  may be modulated variable resistor or potentiometer, or by varying voltage, and the like. The amount of current supplied by the power source  122  may be modulated via a controller directing or including the variable resistor or potentiometer, or directing the varying of the voltage, and the like. 
     The SOEC housing  124  may be a metal, such as stainless steel. The cathode  108  and the anode  110  may each be a ceramic or metal (or metal oxide). An example metallurgy is a nickel alloy to give nickel-based electrodes. The solid electrolyte  120  may be a solid oxide or ceramic. Examples include YSZ or CeO 2 . Other materials that conduct oxygen ions are applicable as the solid electrolyte  120 . 
     While only one SOEC  106  is depicted for clarity, more than one SOEC  106  may be employed. The system  100  may include an SOEC stack having multiple SOECs  106  operationally in parallel. Operating conditions for the SOEC  106  (or SOEC stack) may include an operating pressure at less than 2 atmospheres (atm), such as at about atmospheric pressure (1 atm), and an operating temperature in the range of 500° C. and 950° C. (or 700° C. to 900° C.). Operating conditions may fall outside these exemplary ranges. 
     In operation, CO 2    126  is fed via a conduit to the cathode side  112 . The cathode side  112  has an inlet to receive the CO 2    126 . The respective inlets and outlets of the cathode side  112  and the anode side  116  may be formed through the housing  124 . In operation, the CO 2  is electrochemically reduced at the cathode  108  into CO via the electrons provided from the power source  122 . The CO  128  discharges from an outlet of the cathode side  112  into a conduit for distribution as product or to a catalytic reactor integrated within the system  100 , as discussed below. In the reduction of the CO 2  into CO at the cathode  108 , oxygen ions (O 2− ) are generated and diffuse through the solid electrolyte  120  to the anode side  116 . The reaction or half reaction that takes place at the cathode side  112  may be CO 2 +2e − →CO+O 2− . This reaction or half reaction (electrochemical reduction) is endothermic. 
     The olefin  102  is supplied via a conduit to the anode side  116 . The anode side  116  has an inlet to receive the olefin  102 . The olefin  102  is oxidized (into the olefin oxide  104 ) at the anode  110  via the oxygen ions diffused from the cathode  108 . The anode  110  discharges electrons to the power source  122 . The anode side  116  discharges the olefin oxide  104  through an outlet into a conduit for distribution as product or to a catalytic reactor integrated within the system  100 . The reaction or half reaction that may take place at the anode side  116  is C x H 2x O+O 2− →C x H 2x O+2e − . This oxidation (or partial oxidation) reaction is generally exothermic. 
     The oxidation at the anode  110  may be characterized as a partial oxidation in producing olefin oxide  104  instead of CO 2  and water (H 2 O). As indicated, the oxidation or partial oxidation reaction may be C x H 2x O+O 2− →C x H 2x O+2e − . This reaction is not the result of a separate catalytic reaction but instead via the SOEC  106 . SOECs with electrocatalytic anodes can be utilized for olefin partial oxidation with a specified applied potential ranging, for example, from 1 volt to 3 volts. An example of electrocatalyst for anodic partial oxidation of hydrocarbon is silver (Ag) and Ag-containing materials. 
     The target may be full conversion (via the partial oxidation) of the olefin  102  stream into the olefin oxide  104 . In implementations where full conversion or near full conversion (e.g., 95%) is not achieved, the residual unconverted (not oxidized) olefin in the discharged olefin oxide  104  may be separated and recycled to the anode side  116 . 
     A control valve  130  may be disposed on the conduit conveying the olefin  102  to modulate the flow rate of the olefin  102  to the anode side  116 . The control valve  130  may instead be disposed on the discharge conduit conveying the olefin oxide  104 . The amount of olefin  102  fed to the anode side  116  may depend, for example, on the specified production rate of the olefin oxide  104 , which can be affected by the SOEC  106  production capacity of olefin oxide and other factors. The control valve  130  may be a flow control valve that controls mass rate or volumetric rate of the olefin  102  stream. The control valve  130  may be a pressure control valve that controls pressure by modulating the flow rate of the olefin  102  stream. For example, pressure may be controlled upstream or downstream of the control valve  130 . 
     As for the CO 2 , the amount (rate) of CO 2    126  fed to the cathode side  112  may be set or modulated to generate a specified amount (rate) of oxygen ions to migrate to the anode side  116 . The amount (flow rate) of CO 2    126  may be modulated by a control valve (not shown) disposed on the supply conduit conveying the CO 2    126  or modulated by an upstream CO 2  mechanical compressor, and the like. The flow rate of the CO 2    126  stream, which may include additional compounds (e.g., H 2 O), may be modulated and controlled by the control valve. For implementations where flue gas is the CO 2    126  stream, the control valve may modulate the flow rate of the flue gas fed to the cathode side  112  of the SOEC. 
     An adequate number of oxygen ions are generated at the cathode  108  for the oxidation on the anode side  116 . For the partial oxidation on the anode  110 , one oxygen ion per olefin  102  molecule is utilized. This migration of the oxygen ions from the cathode  108  to the anode  110  may be affected by the cathode  108  catalyst, ion conductivity of the solid electrolyte  120 , and SOEC operating conditions such as temperature and applied electric potential by the power source. The cathode  108  catalyst may be, for example, metals, metal oxides, ceramic oxides of perovskite structure and alloys. The cathode  108  catalyst may include, for example, Li 2 MSiO 4  (LMS), Li 2 CoSiO 4  (LCS), Li 2 NiSiO 4  (LNS), LiNi 1-X-Y Co X Mn Y O 2 , (La,Sr)CoO 3  (LSC) with different La—Sr ratios, La 1-x SrxCr 1-y M y O 3  (M=Mn, Fe, Co, Ni), (La,Sr)(Fe,Co)O 3  (LSCF), (Sm,Sr)CoO 3  (SSC), and (Ba,Sr)(Co,Fe)O 3  (BSCF). 
     The system  100  may include a control system  132  having a processor  134  and memory  136  storing code  138  (e.g., instructions, logic, etc.) executed by the processor  134 . The control system  132  may be or include one or more controllers. The control system  132  may direct operation of the system  100 . In certain implementations, the control system  132  or controller regulates the amount of electric current provided to the cathode  108  from the power source  122 . The control system  132 , via calculation or user-input, may direct and specify the set point of the control valve  130  and also the control valve on the CO 2  supply. 
     The processor  134  may be one or more processors and each processor may have one or more cores. The hardware processor(s)  134  may include a microprocessor, a central processing unit (CPU), a graphic processing unit (GPU), a controller card, or other circuitry. The memory  136  may include volatile memory (for example, cache and random access memory (RAM)), nonvolatile memory (for example, hard drive, solid-state drive, and read-only memory (ROM)), and firmware. The control system  132  may include a desktop computer, laptop computer, computer server, programmable logic controller (PLC), distributed computing system (DSC), controllers, actuators, or control cards. In operation, the control system  132  may facilitate processes of the system including to direct operation of the SOEC  106 . The control system  132  may receive user input or computer input that specifies the set points of control components in the system  100 . The control system  132  may determine, calculate, and specify the set point of control devices. The determination can be based at least in part on the operating conditions of the system  100  including feedback information from sensors and transmitters, and the like. 
     In certain embodiments, the CO 2    126  stream fed to the SOEC cathode side may be primarily CO 2 , such as greater than 50 weight percent (wt %) CO 2 , greater than 80 wt % CO 2 , or greater than 90 wt % CO 2 . The CO 2    126  stream may be greater than 50 volume percent (vol %) CO 2 , greater than 80 vol % CO 2 , or greater than 90 vol % CO 2 . In embodiments, the CO 2  may be a component at less than 50 wt % (or less than 50 vol %) of the CO 2    126  stream fed to the cathode side of the SOEC. 
     In some embodiments, the CO 2    126  feed may also include water (H 2 O). The stream fed to the cathode side  112  may include both CO 2  and H 2 O. In particular implementations, the CO 2    126  stream supplied to the SOEC cathode side  112  may be a flue gas having the CO 2  and H 2 O, and additional components. 
     Any H 2 O fed with the CO 2    126  stream may also be subjected to electrochemical reduction (into H 2 ) at the SOEC cathode  108  to generate O 2−  ions. These O 2−  ions may also migrate to the anode  110  and are utilized in the oxidation of the olefin  102  at the anode  110 . The produced H 2  may discharge in the CO  128  stream exiting from the outlet of the cathode side  112 . In examples, the produced CO  128  stream having the H 2  may be fed to the catalytic reactor (or series of catalytic reactors) for conversion to a compound (e.g., a hydrocarbon compound). 
     Flue gas may be an output of a combustion and include the combustion products CO 2  and H 2 O. In examples, flue gas may also be labeled as exhaust or stack gas. The composition of the flue gas may depend on the fuels or wastes combusted. Fuels combusted may include fossil-based fuels, such as natural gas or coal. 
     In addition to CO 2  and H 2 O, components in the flue gas may include nitrogen (N 2 ), oxygen (O 2 ), carbon monoxide (CO), nitrogen oxides (NO x ), sulfur dioxide (SO 2 ), hydrogen sulfide (H 2 S), and other components, as well as particulate matter. In implementations, the volume concentration of CO 2  in the flue gas may be, for example, less than 25% or less than 15%. The volume concentration of H 2 O in the flue gas may be, for example, less than 25% or less than 20%. 
     As discussed below with respect to  FIG. 2 , the system  100  may include a catalytic reactor or series of catalytic reactors to convert the olefin oxide  104  or CO  128 , or both, into a valuable hydrocarbon. The anode side  116  may discharge the olefin oxide  104  through the discharge conduit to the catalytic reactor or series of catalytic reactors ( FIG. 2 ). The system  100  may include a motive device (e.g., compressor) disposed along the discharge conduit from the anode side  116  to provide motive force for flow of the olefin oxide  104  to the catalytic reactor. 
     In some implementations, the cathode side  112  may discharge the CO  128  stream (including any H 2 ) to the catalytic reactor or series of catalytic reactors. The system  100  may include a motive device (e.g., compressor) disposed along the conduit conveying the CO  128  to provide motive force for flow of the CO  128  to the catalytic reactor from the cathode side  112 . 
       FIG. 2  is a catalytic reactor  200  that may receive from the SOEC  106  ( FIG. 1 ) the produced olefin oxide  104  and CO  128  (and any H 2  along with the CO) to generate acrylic acid (C 3 H 4 O 2 ) or other hydrocarbon. The system  100  of  FIG. 1  may incorporate the catalytic reactor  200 . The catalytic reactor  200  may be a single-step or multi-step catalytic reactor. The catalytic reactor  200  may represent a series of reactors or an initial reactor in the series of reactors. The catalytic reactor  200  generally has a catalyst  202 . The type of catalyst  202  may depend on the reaction(s) in the catalytic reactor  200 . The catalyst  202  employed may depend on the hydrocarbon (e.g., precursor, intermediate, or product) generated in the catalytic reactor(s)  200  and that exits as hydrocarbon  204  in a discharge stream. 
     In operation, one or both of the olefin oxide  104  and the CO  128  may be fed to the catalytic reactor  200 . The feed catalytically reacts via the catalyst  202  to give the  204 , which may be produced hydrocarbon, polymer, or plastic. The product  204  may be acrylic acid, an alcohol, an ether, an ester, etc. For example, hydrolysis of the olefin oxide  104  in presence of an acid catalyst as the catalyst  202  may generate glycol as the product  204 . Ethylene oxide or propylene oxide as the olefin oxide  104  may be subjected to hydrolysis to give ethylene glycol or propylene glycol, respectively, as the product  204 . In other examples, polyether rubbers as the product  204  may be derived from olefin oxides  104 . In yet another example, the product  204  may be bisphenol A diglycidyl ether produced from ethylene oxide as the olefin oxide  104 . In other implementations, the olefin oxide  104  (e.g., ethylene oxide, propylene oxide, butylene oxide, etc.) may be reacted with ammonia to produce corresponding alkanolamines (containing a hydroxyl group) as the hydrocarbon product  204 . Moreover, ethylene oxide as the olefin oxide  104  may be utilized to generate detergents or surfactants as the product  204  by ethoxylation. Additional examples are applicable. 
     The product  204  may be a precursor for a polymer or plastic. For instance, an epoxy may be formed from the product  204  as ethylene-oxide based precursors. The product  204  itself may be a polymer or plastic. 
     In some implementations of the olefin oxide  104  as ethylene oxide (C 2 H 4 O), the catalytic reactor  200  converts the ethylene oxide and the CO into a precursor that is a propiolactone (C 3 H 4 O 2 ) (e.g., β-propiolactone) for the production of acetic acid. In these implementations, the ethylene oxide is carbonylated with the CO in the presence of the catalyst  202  as a cobalt catalyst system [e.g., Co(CO) 4 ] to produce the precursor C 3 H 4 O 2 . The carbonylation reaction may be C 2 H 4 O+CO→C 3 H 4 O 2 . The precursor propiolactone may discharge from the catalytic reactor  200  as the hydrocarbon  204  for distribution. 
     Alternatively, the precursor propiolactone may discharge from the catalytic reactor  200  to a second catalytic reactor  200  that converts the propiolactone into acrylic acid as the hydrocarbon  204  stream discharging from the second catalytic reactor  200 . In one example, the catalyst  202  in this second reactor for the conversion of the β-propiolactone to acrylic acid is a phosphoric acid catalyst. Other syntheses and configurations for the conversion of the olefin oxide  104  (and CO  128 ) into acrylic acid are applicable. 
       FIG. 3  is a method of operating a system having an SOEC. In some implementations, the SOEC may be one SOEC of a stack of multiple SOECs arranged operationally in parallel. 
     At block  302 , the method include supplying (feeding) CO 2  and olefin to the SOEC. In particular, the CO 2  is supplied to the cathode side of the SOEC and the olefin is supplied to the anode side of the SOEC. The method may include modulating an amount of the olefin fed to the anode side. The amount of CO 2  fed to the cathode side may also be controlled and altered. 
     The method may include supplying H 2 O along with the CO 2  to the cathode side. The method include supplying a flue gas having the H 2 O and the CO 2  to the cathode side. If flue gas is utilized, the amount of flue gas fed to the cathode side may be modulated and controlled. In examples with the presence of water in the feed with the CO 2  to the cathode side, the electrochemical reduction reactions at the cathode may include: CO 2 +2e − →CO+O 2− ; and (2) H 2 O+2e − →H 2 +O 2− . 
     At block  304 , the method includes applying electric current to the cathode of the SOEC. The power source that supplies the electric current may be a battery. The electric current is supplied to provide electrons to the cathode for the electrochemical reduction at the cathode. The amount of electric current applied may be modulated and adjusted. 
     At block  306 , the method includes electrochemically reducing the CO 2  at the cathode into CO and generating oxygen ions via the electrochemical reduction. The electrochemical reduction relies on the electrons supplied to the cathode from the power source. The reaction or half reaction that takes place at the cathode may be CO 2 +2e − →CO+O 2− . 
     The method may additionally include electrochemically reducing H 2 O at the cathode into H 2  and generating oxygen ions via the electrochemical reduction. This electrochemical reduction (if occurring) also relies on the electrons supplied to the cathode from the power source. The reaction or half reaction that takes place at the cathode may thus also include be H 2 O+2e − →H 2 +O 2− . 
     At block  308 , the method includes diffusing the generated oxygen ions (at the cathode) through the solid electrolyte of the SOEC from the cathode to the anode. The solid electrolyte is generally a solid oxide or ceramic. This migration of the oxygen ions (O 2− ) from the cathode to the anode may be affected by the cathode catalyst, ion conductivity of the solid electrolyte, and SOEC operating conditions such as temperature and applied electric potential by the power source. 
     At block  310 , the method includes oxidizing (e.g., via partial oxidation) the olefin at the anode with the oxygen ions into an olefin oxide. The anode may discharge (release) electrons to the power source. The olefin oxide produced may generally correspond to the olefin. For instance, if the olefin is ethylene, the olefin oxide may be ethylene oxide. In another example, if the olefin is propylene, the olefin oxide generated may be propylene oxide. 
     At block  312 , the method includes discharging the olefin oxide and the CO (and any produced H 2 ) from the SOEC. In particular, the olefin oxide is discharged from the anode side and the CO is discharged from the cathode side. Both the olefin oxide and the CO (and any produced H 2 ) may be collected for distribution as products. For CO streams having produced H 2 , the stream having both CO and H 2  may be collected for distribution as a product (e.g., labeled as a syngas in some instances). 
     The olefin oxide and CO (and any produced H 2 ) may be discharged to a catalytic reactor or series of catalytic reactor, as discussed with respect to block  314  below. In some implementations, the catalytic reactor(s) may be integrated within the system having the SOEC. 
     At block  314 , the method may include catalytically converting the olefin oxide and the CO (and any produced H 2 ) into a hydrocarbon having higher value than the olefin oxide. This catalytic conversion may be performed in a catalytic reactor or series of catalytic reactors. The hydrocarbon product from the conversion of the olefin oxide may be, for example, acrylic acid, an alcohol, an ether, or an ester. In the case of acrylic acid, the olefin oxide fed from the SOEC to the catalytic reactor for the conversion may be ethylene oxide. In certain implementations, the ethylene oxide may be first converted to a precursor (e.g., a propiolactone) for the acrylic acid, and then the precursor converted to acrylic acid. 
     An embodiment is a method of operating a system having an SOEC. The method includes feeding CO 2  and an olefin to the SOEC, modulating an amount of the olefin fed to the SOEC, and discharging CO and an olefin oxide from the SOEC, wherein the olefin oxide corresponds to the olefin. The method may include supplying electric current to a cathode of the SOEC and electrochemically reducing the CO 2  at the cathode into the CO, wherein electrochemically reducing the CO 2  generates oxygen ions. The method may include modulating an amount of the electric current supplied to the cathode. The method may include diffusing the oxygen ions through a solid electrolyte of the SOEC to an anode of the SOEC and oxidizing the olefin at the anode into the olefin oxide via the oxygen ions. In implementations, the method may include feeding H 2 O to the SOEC, electrochemically reducing the H 2 O at the cathode into H 2  (wherein electrochemically reducing the H 2 O generates oxygen ions), and discharging the H 2  from the SOEC. In these implementations, the feeding of the CO 2  and the feeding of the H 2 O (in combination or together) may involve feeding flue gas to the SOEC. 
     The discharging of the olefin oxide may include discharging the olefin oxide to a catalytic reactor. The method may include converting the olefin oxide via the catalytic reactor into at least one of acrylic acid, an alcohol, an ether, an ester, or a precursor for acrylic acid. In some implementations, the catalytic reactor is a series of catalytic reactors and the olefin oxide is converted into acrylic acid. The converting of the olefin oxide into acrylic acid may involve converting the olefin oxide into the precursor that is converted into acrylic acid, and wherein the olefin oxide is ethylene oxide. 
     Another embodiment is a method of operating a system having an SOEC. The method includes receiving electric current at a cathode of the SOEC and electrochemically reducing CO 2  at the cathode via electrons of the electric current to generate CO and oxygen ions. The method includes diffusing the oxygen ions through a solid electrolyte (including a solid oxide) to an anode of the SOEC and oxidizing an olefin at the anode via the oxygen ions into an olefin oxide. The method may include modulating an amount of the electric current received at the cathode. In certain implementations, the method may include electrochemically reducing H 2 O at the cathode via electrons of the electric current to generate hydrogen and oxygen ions. The method may include providing a flue gas having the CO 2  and the H 2 O to a cathode side of the SOEC. The method may include modulating the amount of olefin received at the anode. In some implementations, the method may include discharging the olefin oxide from an anode side of the SOEC to a catalytic reactor and converting the olefin oxide via the catalytic reactor into a compound including a hydrocarbon. The catalytic reactor may be a series of catalytic reactors. The catalytic reactor may be a first reactor in series of catalytic reactors. In particular implementations, the olefin fed to the SOEC is ethylene and the produced olefin oxide is ethylene oxide that is converted into the hydrocarbon being acrylic acid. 
     Yet another embodiment is a system having an SOEC to receive CO 2  and an olefin and discharge CO and an olefin oxide. The system includes a conduit to supply the olefin to the SOEC. A control valve is disposed along the conduit to modulate an amount of the olefin supplied to the SOEC. The system may include a controller to direct a set point of the control valve. The system includes a second conduit to supply the CO 2  to the SOEC. The SOEC may include: (1) a cathode to electrochemically reduce the CO 2  and generate oxygen ions and the CO, wherein the cathode is coupled to a power source to supply electric current to the cathode; (2) a solid electrolyte to diffuse the oxygen ions from the cathode to an anode, wherein the solid electrolyte includes a solid oxide; and (3) the anode to oxidize, via the oxygen ions, the olefin into the olefin oxide. The system may include a controller to modulate an amount of the electric current supplied to the cathode, wherein the cathode electrochemically reduces the CO 2  to the CO via the electric current. The system may include the power source (e.g., a battery) to supply the electric current to the cathode. The system may include a catalytic reactor to convert the olefin oxide into a hydrocarbon different than the olefin oxide, wherein the catalytic reactor has an inlet to receive the olefin oxide. 
     Yet another embodiment is an SOEC system having an SOEC. The SOEC includes a cathode to electrochemically reduce carbon dioxide into carbon monoxide and oxygen ions and discharge the oxygen ions into a solid electrolyte of the SOEC. The SOEC includes an anode to receive the oxygen ions via the solid electrolyte from the cathode and oxidize an olefin with the oxygen ions into an olefin oxide corresponding to the olefin. The SOEC system includes a feed conduit to supply the carbon dioxide to a cathode side of the SOEC. The cathode side includes the cathode. In some implementations, the feed conduit to supply a flue gas having the carbon dioxide and also water to the cathode side. The SOEC system includes a second feed conduit to supply the olefin to an anode side of the SOEC. The anode side includes the anode. In implementations, the SOEC system may include a control valve disposed along the second feed conduit to modulate the amount of the olefin supplied to the cathode side. The SOEC system may be coupled to or include a power source to supply electric current to the cathode. The power source may be, for example, a battery, a power generator, or an electrical grid, or any combinations thereof. The SOEC system may include a controller to modulate the amount of the electric current receive at (or supplied to) the cathode. The SOEC may include a conduit to discharge the olefin oxide to a catalytic reactor. The SOEC may include a second conduit to discharge the carbon monoxide to the catalytic reactor. 
     A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.