Integrated TRI-reforming system and method

Abstract

A method and system for integrating tri-reforming and water or steam electrolysis includes reacting methane, CO2, H2O, and O2 in a methane tri-reformer to form syngas, which includes H2 and CO. The electrolysis of water or steam is performed in an electrolyzer to produce H2 at the cathode and O2 at the anode. The O2 generated by the electrolyzer is provided to the methane tri-reformer for use as a reactant to form the syngas. The system and method may also include additional processes such as hydroformylation, methanol synthesis, and oxy-combustion.

Description

INTEGRATED TRI-REFORMING SYSTEM AND METHODBACKGROUND

[0001] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0002] Carbon capture, utilization, and storage (CCUS) is generally a process intended to reduce the level of carbonaceous gases (most commonly carbon dioxide (CO2)) within the atmosphere. This may include the capture of carbonaceous gases from sources of emissions so that they do not enter the atmosphere, or to directly remove the carbonaceous gases from the atmosphere. In some instances, the captured gases may be used in other processes, such as in the production of new materials, chemicals, and so forth, or as a process gas. Alternatively, the captured carbonaceous gases may be stored (sequestered) in a variety of ways, such as through chemical transformation and / or injection into a geological formation.

[0003] CCUS in general may afford operators in the oil and gas industry an opportunity to enhance efficiencies while also reducing carbon intensity in their operations. One process that utilizes carbonaceous gases such as CO2 and methane to produce useful materials is a trireforming process.

[0004] In the tri-reforming process, hydrocarbons (primarily methane) can be considered to undergo three reforming reactions (aside from potential side reactions) in one reactor: one with CO2 (dry reforming), one with H2O (steam reforming), and one with O2 (partial oxidation) - each of which form synthesis gas (syngas). The primary components of syngas are H2 and CO, which can be used to make a number of different high value products such as methanol, dimethyl ether (DME), and Fischer-Tropsch products.

[0005] Some attractive aspects of tri-reforming are that the reactants can be combined without the need for upstream separation and that the ratio of H2 to CO (referred to herein in shorthand form as the “syngas composition”) can be controlled within a certain window by controlling the amounts of reactants provided to the TRM. It is now recognized that it may be beneficial to additionally control the syngas composition using process streams that are outside of the trireforming process. It is also now recognized that certain processes can be integrated with the tri-reforming process to enhance plant efficiencies.SUMMARY

[0006] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure or of embodiments of the invention. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0007] In accordance with an embodiment of this disclosure, a method for integrating trireforming and water or steam electrolysis in a system includes reacting methane, CO2, H2O,and O2 in a methane tri-reformer (TRM) to form syngas, the syngas including H2 and CO. The method also includes performing electrolysis of water or steam in an electrolyzer to produce H2 at a cathode of the electrolyzer and O2 at an anode of the electrolyzer; and providing at least some of the O2 generated by the electrolyzer to the TRM for use as a reactant to form the syngas.

[0008] In another embodiment of this disclosure, a system includes a methane tri-reformer (TRM) configured to react methane, CO2, H2O, and O2 to form syngas, the syngas including H2 and CO. The system also includes an electrolyzer configured to electrolyze H2O to produce H2 at a cathode of the electrolyzer and O2 at an anode of the electrolyzer. The TRM and the electrolyzer are integrated such that the O2 generated at the anode is provided to the TRM.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure. The inventive concepts associated with the present disclosure will be more readily understood by reference to the following description in combination with the accompanying drawings, wherein:

[0010] FIG. 1 is an example embodiment of a process and system for integrating tri-reforming and steam electrolysis, in accordance with an embodiment of this disclosure;

[0011] FIG. 2 is an example embodiment of another process and system for integrating trireforming and steam electrolysis, in accordance with an embodiment of this disclosure;

[0012] FIGS. 3 and 4 are example embodiments of a process and system for integrating trireforming, water electrolysis, and methanol synthesis, in accordance with an embodiment of this disclosure;

[0013] FIG. 5 is an example embodiment of a process and system for integrating tri-reforming, steam electrolysis, and oxy combustion, in accordance with an embodiment of this disclosure;

[0014] FIG. 6 is an example embodiment of a process and system for integrating tri-reforming, water electrolysis, and hydroformylation, in accordance with an embodiment of this disclosure;

[0015] FIG. 7 is a chart showing percent methane and carbon dioxide conversion for a first catalyst under example tri-reforming testing conditions;

[0016] FIG. 8 is a chart showing the hydrogen / carbon monoxide ratio produced under example tri-reforming testing conditions for a first catalyst;

[0017] FIG. 9 is a chart showing is a chart showing percent methane and carbon dioxide conversion for a second catalyst under example tri-reforming testing conditions; and

[0018] FIG. 10 is a chart showing the hydrogen / carbon monoxide ratio produced under example tri-reforming testing conditions for a second catalyst.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0019] The disclosure generally relates to integrating tri-reforming with processes that can enhance the operability within a plant / refmery by allowing flexibility with the reforming product composition while reducing potential carbon intensity associated with such processes.More particularly, tri-reforming may be integrated with water / stream electrolysis and other processes such as hydroformylation.

[0020] A process and system 10 for integrating the tri-re forming and water / steam electrolysis according to example embodiments is generally shown in Figures 1-4. Referring now to Figure 1, the illustrated embodiment of the system 10 includes a methane tri-reformer (TRM) 12 configured to perform the tri-reforming process. The TRM 12 may be an autothermal reactor, where endothermic reactions (e.g., dry reforming and stream reforming) are balanced with exothermic reactions (e.g., partial oxidation using oxygen). During this process, a hydrocarbon gas 14, such as methane (CH4) or natural gas, is reacted with CO2 16 or flue gas, H2O 18, and O2 (in this embodiment, as a part of combined O2 and sweep stream 20) using a catalyst to form a synthesis gas output 22. More specifically, in an autothermal reformer, the reformer includes (1) a partial oxidation section where a portion of the natural gas feed is partially combusted to form CO and H2O in an exothermic reaction, followed by (2) the highly endothermic reforming reactor where steam and CO2 react with the partially-oxidized gas over a reforming catalyst. The reaction is autothermal in that the heat from the partial oxidation step drives the endothermic reforming reaction without the need for external heating.

[0021] The TRM 12 is operated at high temperature and high pressure to facilitate the trireforming process. Example high temperatures include between 800 °C and 1100 °C, and example high pressures include between 5 and 35 bar. The catalyst used in the TRM 12 is preferably a Ni-based catalyst (e.g., Ni / W on alumina or Ca / Mg oxide), but other types of catalysts can be used. The primary components of the synthesis gas produced are H2 and CO. During the tri-reforming process, the O2 partially oxidizes the methane in an exothermicreaction. In certain embodiments, the tri-reforming process can be controlled such that the temperature at the outlet of the TRM 12 is higher than the temperature at the inlet of the TRM 12 by balancing the various reactions within the TRM 12.

[0022] The TRM 12 may be operated at conditions such that the ratio of H2 / CO at the outlet of the TRM 12 is less than 2.0, for example in the range of 1.3 to 1.4, though the TRM 12 may produce other ratios such as 1.0. The TRM 12 may also be operated such that the conversion of CH4 is greater than 99% and the conversion of CO2 is greater than 10 %. Again, the CO2, H2O, O2, and CH4 are all reacted together in the same TRM 12.

[0023] In some embodiments, the hydrocarbon gas 14 fed to the TRM 12 includes heavy hydrocarbons, such as C2, C3, and C4+ hydrocarbons. To reduce or avoid side reactions associated with these heavy hydrocarbons, the system 10 may include a pre-reforming reactor 24 upstream of the TRM 12. In the pre -reforming reactor 24, the heavy hydrocarbons are first reacted with H2O to partially convert the heavy hydrocarbons to CH4, CO, CO2 and H2 as a pre-reformer effluent 25. The CH4, CO, CO2 and H2 at the outlet of the pre-reforming reactor 24 are then combined with the CO2 and O2 and provided to the TRM 12.

[0024] In accordance with embodiments of this disclosure, the illustrated system 10 further includes an electrolyzer 26, such as a solid oxide electrolysis cell (SOEC), a polymer electrolyte membrane (PEM) electrolyzer, or an alkaline electrolyzer for performing water or steam electrolysis (depending on the electrolyzer). The electrolyzer 26 includes an anode and a cathode. In the illustrated embodiment, the electrolyzer 26 is an SOEC. SOEC electrolyzers use steam, and in this embodiment steam 28 is fed to the SOEC electrolyzer 26 for electrolysis using a solid oxide electrolyte. Non-limiting example solid oxide electrolytes include solidceramic materials such as zirconia-based materials, ceria-based materials, or other alkali earth solid oxide-based materials.

[0025] As depicted, to prepare the steam 28 used for electrolysis by the SOEC electrolyzer 26, liquid water 18 is pressurized using pump 30 and preheated by heater 32 to a high temperature, for example 750 °C to 850 °C, and electrochemically split it into O2 at the anode and H2 at the cathode. For the SOEC electrolyzer 26, the reaction occurring at the anode is 2O2— O2+ 4 c ; the reaction occurring at the cathode is H2O + 2H2 + O1; and the net reaction is 2H2O — 2H2 + O2. Unconverted water stays on the cathode side with the H2.

[0026] In accordance with embodiments of this disclosure, the oxygen generated at the anode is controllably provided to the TRM 12, which enables adjustment of the reagent ratios used in the reforming process, while hydrogen (as a part of stream 34) generated at the cathode is used to controllably adjust the ultimate ratio of H2 to CO of a syngas product 35 output by the system 10. Thus, in some embodiments the steam electrolysis process using the SOEC electrolyzer 26 is combined with the tri-reforming process described above by providing the H2 and unreacted H2O from the cathode (stream 34) of the SOEC electrolyzer 26 to the outlet of the TRM 12, such that the final ratio of H2 / CO is, by way of non-limiting example, at least 2.0, such as between 2.0, 2.2, or 2.4 and 3.0, 2.8, 2.6, 2.4, or 2.2. The system 10 thus includes a line or another type of connection 36 between the cathode of the SOEC electrolyzer 26 and an effluent path 38 that carries reactor effluent (the synthesis gas output 22) from the TRM 12.

[0027] The steam electrolysis and tri-reforming process can be integrated in additional ways to enhance operability of the electrolyzer 26. As depicted and by way of example, to facilitate the handling of pure O2 at high temperatures and pressures the CO2 stream 16 that is used as areagent in the TRM 12 is first compressed using compressor 39 and is subsequently provided the SOEC electrolyzer 26 as a sweep gas for the anode of the electrolyzer 26. In this way, the stream of combined O2 and CCh / flue gas 20 is output from the electrolyzer 26. Other process streams may be used as a sweep gas at the anode of the SOEC electrolyzer 26, and other example configurations are depicted in FIGS. 2 and 3 and are discussed in further detail herein.

[0028] In the illustrated embodiment, the system 10 includes various features to pressurize and heat or cool streams of feeds and reactor outputs. Regarding the feeds to the TRM 12, by way of example, a hydrocarbon feed flow path 40 delivers the stream of methane or natural gas (or other hydrocarbon) 14 to the pre-reformer 24. Features such as a hydrocarbon compressor 42 and a pre-reformer heater 44 are located along the hydrocarbon feed flow path 40 to compress and heat the materials in the flow path 40 to produce a pre-reformer feed 45. The system 10 also includes a connection 46 between a water feed path 48 and the hydrocarbon feed flow path 40 to allow the stream of natural gas 14 to mix with a portion of the water 18 upstream of the pre-reformer 24. In the illustrated embodiment, the connection 46 is along the hydrocarbon feed flow path 40 between the compressor 42 and the heater 44, though it may be positioned at other locations upstream of the pre-reformer 24.

[0029] The water feed 18 ultimately provided to the TRM 12 is pumped via water pump 30 and subsequently split between a portion that flows to the water feed path 48 and another portion that becomes the steam 28. A heat exchanger 50 exchanges heat between the water feed flow path 48 and the TRM effluent flow path 38 to heat the water feed 18 and cool the effluent 22.

[0030] In regards to the reactor outputs, the system 10 includes a connection 52 that combines the pre -reformer effluent 25 and the O2 and sweep gas stream 20 to produce a combined TRM feed 54. Another heat exchanger 56 exchanges heat between the combined TRM feed 54 and the TRM effluent 22 to cool the TRM effluent 22 and heat the TRM feed 54.

[0031] The temperatures, pressures, flow rates, and power levels provided in Figure 1 are only examples, and other temperatures, pressures flow rates, and power levels can be used.

[0032] In the configuration of FIG. 1, the CCh / flue gas stream 16 is used as a sweep stream of the anode of the electrolyzer 26. Other process streams may be used as a sweep gas at the anode of the SOEC electrolyzer 26, either in addition to or in lieu of the stream 16. According to another example embodiment, as shown in FIG. 2, the system 10 includes a slipstream 60 of steam (H2O) that would otherwise go directly to the pre-reforming reactor 24 or TRM 12, as a sweep gas for the anode of the electrolyzer 26. A resulting combined O2 and H2O stream 62 is then fed to the TRM 12 where both gases are allowed to react with CH4 to form syngas. As in the embodiment of FIG. 1, this facilitates handling pure O2 at high temperatures and pressures. Further, to the extent the equivalent elements are present, the example parameters presented in Table 1 for FIG. 1 are also app liable to the configuration shown in FIG. 2.

[0033] The system 10 of FIG. 2 includes a CO2 flow path 64 to carry the CO2 stream 16 toward the TRM 12, and specifically to a connection 66 that combines the pre-reformer effluent 25 with the CO2 stream 16 and the anode O2 and sweep gas stream 62.

[0034] As noted above, the electrolyzer 26 may have any one of three different configurations- SOEC, PEM, or alkaline electrolyzer configurations. FIG. 3 illustrates an exampleembodiment of the system 10 where the electrolyzer 26 is a polymer electrolyte membrane (PEM) electrolyzer (sometimes referred to as a proton exchange membrane electrolyzer) that includes a polymer membrane such as a perfluorinated sulfonic acid membrane (e.g., NAFION™ made by DuPont). The PEM electrolyzer 26 includes an anode and cathode and may use, for example, carbon-free electricity to split water into O2 at the anode and H2 at the cathode. As with the embodiment depicted in FIGS. 1 and 2, the O2 produced at the anode of the electrolyzer 26 may be used for the tri-reforming process while the EE may be used to adjust the H2 / CO ratio of the syngas produced by the system 10.

[0035] In some embodiments, using the PEM electrolyzer in place of the SOEC enables high- pressure, low-temperature O2 generation, so a separate sweep system to provide O2 may not be needed. Therefore, an anode stream 68 produced by the electrolyzer 36 of FIG. 3 may be relatively low temperature O2 without a sweep gas. However, the PEM electrolyzer is less efficient than the SOEC, so the electricity demand is higher. The PEM electrolyzer may also have a reduced heat requirement compared to the SOEC electrolyzer, since feed water 69 to the electrolyzer 26 only needs to be heated to about 80 °C and not 800 °C. The temperatures, pressures, flow rates, and power levels discussed with respect to FIG. 3 are only examples, and other temperatures, pressures flow rates, and power levels can be used.

[0036] In the system 10 of FIG. 3, the pre-reforming reactor 24 is typically not required. However, the pre-reforming reactor 24 can be added when the natural gas stream 14 contains heavier hydrocarbons. It may not be needed for biogas or lean natural gas. The system 10 may intake the CO2 or flue gas 16 discussed above with respect to FIG. 1, and additionally or alternatively a tail gas external recycle stream 70 from a separate process (e.g., another processthat is a part of a refinery in which the system 10 is located). In the illustrated embodiment, the tail gas external recycle stream 70 includes a majority CO2, with minor amounts of methanol, methane, and hydrogen.

[0037] The CO2 or flue gas 16 and / or the tail gas external recycle stream 70 are provided along a CO2 flow path 72 toward the TRM 12. Compressor 39 operates on either or both streams. In this embodiment, The CO2 flow path 72, the hydrocarbon flow path 40, and an anode stream flow path 74 for the anode stream 68 converge at connection 76 to generate the TRM feed 54.

[0038] An example embodiment of a system 80 configured to produce the tail gas external recycle stream is depicted in FIG. 4. In particular, the system 80 may be considered to receive the syngas product 35 generated by the system 10 of FIG. 3, and in this way the system 10 and the system 80 may be considered to be a part of a larger system, such as part of a refinery. The system 80 may be a downstream part of the system 10. Other reactions may be integrated with the system 10 in addition to or in lieu of methanol synthesis as described herein. Indeed, the system 80 may be considered to represent any syngas conversion process. Non-limiting examples include Fisher-Tropsch type processes for making wax, diesel, or gasoline.

[0039] In the system 80, the syngas 35 is pre-processed, which may include using a cooler 82, water knockout 84, and compressor 86, among other processes. The system 80 includes a methanol (MeOH) synthesis reactor 88 configured to convert syngas to MeOH.

[0040] In a general sense, unreacted syngas from the MeOH synthesis reactor 88 is divided between a tail gas internal recycle 90 and the tail gas external recycle 70, where the tail gas external recycle is the tail gas external recycle stream that is fed to the TRM 12 of FIG. 3. The tail gases are primarily CO2, with some methanol and unreacted syngas as shown by way of example in Table 2.

[0041] In the illustrated embodiment, the methanol synthesis reactor 88 generates a methanol output 92 (shown as coming from the top of the reactor 88), which undergoes heat exchange at HX 94 with the syngas stream 35 and the tail gas internal recycle stream 90 (and thereby generating the MeOH synthesis reactor feed 96).

[0042] The methanol output 92 then undergoes various processing steps including cooling at cooler 98 and pressure letdown at vessel 100 to generate methanol stream 102 and the tail gas internal recycle stream 90. The methanol stream 102 is further degassed at vessel 104, heated at heater 106, degassed again at vessel 108, and finally separated at separator 110 to generate a methanol product 112 and a wastewater stream 114.

[0043] The system 80 also produces a tail gas to fuel stream 116 from the overhead discharge of vessels 100, 104, and 108. The tail gas to fuel stream 116 may be used as fuel or combined with other fuel streams. The tail gas internal recycle stream 90 may be compressed by compressor 118 for recirculating to the methanol synthesis reactor 88. The tail gas external recycle stream 70 may be compressed by compressor 120 for provision to the system 10 of FIG. 3.

[0044] Example values of operating parameters and the production of the system 80 in FIG. 4 are provided in Table 3 below. The temperatures, pressures, flow rates, and power levels provided in Table 3 are only examples, and other temperatures, pressures flow rates, and power levels can be used.

[0045] Another example embodiment of the system 10 is shown in FIG. 5. Such an embodiment may be used, for example, in cases where there is a surplus of CO2 available and / or the tri-reforming process requires less O2 than is produced by the electrolyzer 26. More specifically, the illustrated embodiment of the system 10 includes integrating the anode stream from the electrolyzer 26 with an oxy-combustion process.

[0046] In the illustrated embodiment of FIG. 5, the CO2 16 is again used as the anode sweep gas, as in the embodiment of FIG. 1. However, instead of sending all the CO2 and O2 mixture directly to the TRM 12, some of the CO2 and O2 mixture 20 is sent through an oxy-combustion boiler / turbine 130. Through the oxy-combustion process, the CO2 and O2 mixture 130 burn a slipstream of CH4 131 to generate process heat and / or power. The use of the CO2 in the feed helps moderate the large temperature exotherm when fuels are burned with pure O2. The heat and power may be used to support other energy requirements of the tri-reforming or syngas conversion processes. In addition, the flue gas from the oxy-combustion process is just CO2 132 and H2O 134. The H2O may be readily condensed, and the resulting CO2 may be used for either sequestration purposes or as recycle back to the TRM 12. The temperatures, pressures, flow rates, and power levels provided with respect to the corresponding elements in FIGS. 1 and 2 are applicable to the system 10 of FIG. 5.

[0047] In accordance with this disclosure, the TRM 12 may be integrated with other types of processes than those described with respect to FIGS. 1-5, either in addition to those processes or in lieu of them. In some embodiments, by way of example and as shown in FIG. 6, the TRM 12 may be integrated with a hydroformylation process. In the depicted embodiment, the system 10 further includes a hydroformylation reactor 150 downstream of the TRM 12. According to this embodiment, the TRM 12 is operated at conditions such that the CO2, H2O, O2, and CH4 are reacted to produce a ratio of H2 / CO of 1 at the outlet of the TRM 12. The H2 / CO ratio of 1.0 is suitable for use in a hydroformylation reaction. The system 10 includes a line or other type of connection 152 between the TRM 12 and the hydroformylation reactor 150 which provides the H2 and CO produced by the TRM 12 to the hydroformylation reactor 150.

[0048] The hydroformylation reaction which occurs in the hydroformylation reactor 150 includes reacting the H2 and CO with an unsaturated compound, typically an alkene or alkyne (e.g., propylene 153), to produce an aldehyde (e.g., butanal 154). An advantage of integrating the tri-reforming process with the hydroformylation according to the embodiment of FIG. 6 is that a portion of CH4 at the inlet of the TRM 12 can be burned with the O2 to produce CO, H2O, and heat to drive the reactions in the TRM 12. Unlike dry-reforming, no external heating is required, and thus significant amounts of CO2 can be converted to CO and eventually incorporated into the liquid products, such as n-butanal and i-butanal.

[0049] In the system 10 of FIG. 6, the electrolyzer 26 is a polymer electrolyte membrane (PEM) electrolyzer integrated with the TRM 12. The O2 generated by the electrolyzer 26 is consumed in the TRM 12 while the H2 generated by the electrolyzer 26 (cathode stream 34) may be used to control the syngas composition or, as depicted, may be sent to one or more hydrogenation reactors 156.

[0050] In some instances of this embodiment, all the H2 produced by the electrolyzer 26 may be used to convert n-butanol to 2-ethylhexanol. In particular, the illustrated system 10 includes a connection 158 between the electrolyzer 26 and the TRM 12 to provide the O2 to the TRM 12. The system 10 further includes a connection 160 between the electrolyzer 26 and the hydrogenation reactor 156 to provide the H2 to the hydrogenation reactor 156. Table 4 includes a table showing the material and energy balances of the process shown in FIG. 6, as compared with a base case where the O2 is provided by a cryogenic plant. When the PEM electrolyzer is driven by carbon-free energy, the overall CO2 footprint is lower. Net CO2 conversion is 29%vs. 16% by integrating the PEM electrolyzer. The other benefit is that the co-produced Eb by electrolysis is beneficially used for creating a higher-value product, such as 2-ethylhexanol.EXAMPLESExample 1

[0051] The example embodiment shown in Figure 1 includes non-limiting examples of flow or processing rates, pressures, power levels, and temperatures. These numbers are non-limiting examples of the way in which the system 10 may be operated. By way of non-limiting example, a first compressor of the system 10 may receive between 2000 and 2200 kgmole / hr at standardtemperature and pressure of methane to pressurize the methane. A second compressor of the system 10 may receive between 2000 and 3000 kgmole / hr at standard temperature and pressure of CO2, which is eventually used as the electrolyzer anode sweep and as feed to the TRM 12. The system 10 also receives water at an amount between 5000 and 6000 kgmole / hr at standard temperature and pressure, some of which is provided to the electrolyzer 26 (after heating) and some of which is combined with the methane provided to the pre-reformer 14.

[0052] The methane may be heated to between 500 and 600 °C before being delivered to the pre-reformer 24. The CO2 and O2 combination from the electrolyzer 26, may be at a temperature between 400 and 500 °C and a pressure between 20 and 30 bar before it is heat- integrated with the output of the TRM 12 (the output may be, for example, between 900 and 1000 °C at a pressure between 15 and 25 bar) to a temperature between 800 and 900 °C.

[0053] The syngas stream produced by the TRM 12 is heat-integrated not only with the prereformer output and the O2 / CO2 stream, but is subsequently heat-integrated with water that is combined with the methane provided to a pre-reformer heater. This heats the water to between 400 and 600 °C and reduces the temperature of the syngas to between 100 and 200 °C.

[0054] The composition of the syngas is then adjusted using the H2 stream from the cathode of the electrolyzer 26 to the above-noted H2 / CO ratios. The syngas has a temperature of between 150 and 250 °C, and a pressure between 15 and 25 bar, for example.

[0055] Using the specific values shown in Table 1 for FIG. 1, it was simulated that the H2 / CO ratio of the product syngas can be 2.11 with a 99.1% methane and 27.6% CO2 conversion, at a rate of 14,370 kgmole / hr. This may be compared to, for example, a system that utilizes an air separation unit (ASU) rather than an electrolyzer as described herein. Using an ASU togenerate similar values (where the H2 / CO ratio is at 2.0 or slightly above), the integration shown in FIG. 1 may be more efficient in converting CO2 than a base case that uses an ASU. One reason for this is that the TRM 12 can be operated such that it produces an H2 / CO ratio that is lower than 2.0 (e.g., 1.3), and the ratio can be restored above 2.0 using the H2 from the electrolyzer 26.Example 2

[0056] The example embodiment shown in FIG. 3 includes non-limiting examples of flow or processing rates, pressures, power levels, and temperatures. These numbers are non-limiting examples of the way in which the system 10 may be operated. By way of non-limiting example, a first compressor of the system 10 may receive between 1000 and 2000 kgmole / hr at standard temperature and pressure of methane to pressurize the methane. A second compressor of the system 10 may receive between 300 and 700 kgmole / hr at standard temperature and pressure of CO2 in addition to between 250 and 400 kgmole / hr of tail gas external recycle from the system shown in FIG. 4 having a majority CO2 and some methanol, methane, and hydrogen. The tail gas received may have a pressure between 3 bar and 5 bar and a temperature between 60 and 100 °C. The system 10 also receives water at an amount between 2500 and 3500 kgmole / hr at standard temperature and pressure, some of which is provided to the electrolyzer 26 (after heating) and some of which is heated and combined with compressed methane.

[0057] In this embodiment, there is no pre-reformer. Thus, the compressed CEE stream, the compressed combined CCh / tail gas stream, and the O2 stream are mixed and have a temperature between 150 and 200 °C. The combination of these streams is then heat integrated with theoutput of the TRM 12 (the output may be, for example, between 900 and 1000 °C at a pressure between 15 and 25 bar) to a temperature between 800 and 900 °C.

[0058] The syngas stream produced by the TRM 12 is heat-integrated not only with the combined streams, but is subsequently heat-integrated with water that is combined with the compressed methane. This heats the water to between 200 and 400 °C and reduces the temperature of the syngas to between 100 and 200 °C.

[0059] The composition of the syngas is then adjusted using the H2 stream from the cathode of the electrolyzer 26 to the above-noted H2 / CO ratios. The syngas has a temperature of between 100 and 150 °C, and a pressure between 15 and 25 bar with a production rate of between 7500 and 8500 kgmole / hr, for example. Using the specific values shown in Table 2 for FIG. 3, it was simulated that the H2 / CO ratio of the product syngas can be 2.59 with a 99.1% methane and 21.7% CO2 conversion, at a rate of 8086 kgmole / hr.Example 3

[0060] The conversion within the tri-reforming reactor was simulated in a laboratory experiment. In Tri-Reforming, methane is reacted with oxygen, carbon dioxide, and steam to produce synthesis gas. The commercial embodiment is to run the process using an autothermal reformer (ATR) style reactor, which includes (1) a partial oxidation section where a portion of the natural gas feed is partially combusted to form CO and H2O in an exothermic reaction, followed by (2) the highly endothermic reforming reactor where steam and CO2 react with the partially-oxidized gas over a reforming catalyst. The reaction is autothermal in that the heatfrom the partial oxidation step drives the endothermic reforming reaction without the need for external heating.

[0061] In testing catalysts at the laboratory scale, it is oven beneficial to avoid the handling of pure oxygen at high temperatures and pressures for safety reasons. To simulate the trireforming reactor, one can test the catalyst itself with a simulated feed of the partially-oxidized gas feed. In this case, all of the oxygen would have been consumed into CO and H2O through reaction with some of the methane.

[0062] For example, based on a feed with the following to the Tri-Reformer’s partial-oxidation section: Gas Feed A: 815C; 2000 kpag;l kgmole / hr; 34.7 mol% CH4, 17.4 mol% CO2, 30.8% H2O, and 17.1% O2.

[0063] The resulting partially oxidized gas that will contact the catalytic section will have the following characteristics at equilibrium. The partially-oxidized gas is what the catalyst actually sees in the reactor. Gas Feed B: 1724 C; 2000 kpag; 1.06 kgmole / hr; 22.1% CH4, 16.4% CO2, 0% O2, 10.8% CO, 50.7% H2O.

[0064] Under adiabatic conditions, the product gas leaving the catalyst section of a TriReformer will have the following: Gas Product C: 956C; 1900 kpag; 1.498 kgmole / hr; 0.87% CH4, 9.2% CO2, 24.7% CO, 41.8% H2, 23.4% H2O; H2 / CO=1.69; 96.25% CH4conversion, 20.7% CO2 conversion.

[0065] Several Tri-Reforming catalysts were tested in laboratory, packed-bed reactors arranged in parallel and equipped with individual 3 -zone electric heaters to control the reaction temperature. Each reactor was 6 mm I.D. x 600 mm H and had either 0.4-mL or 1-mL of calcined catalyst. The reason for the different volumes is to enable a broader range of gas hourspace velocities (GHSV) to be tested with a given flowrate. The top of each reactor was packed with quartz as an inert material while the bottom was supported with a ceramic chair. Based on the feed flowrates and catalyst volumes tested, a GHSV range of 6000 to 22,500 1 / hr was tested. The inlet and outlet flows were recorded continuously while the gas compositions were determined by GC. A small amount of argon (~5% of the entire gas composition) was added as an internal standard for all experiments.

[0066] The catalysts were tested over many different feed conditions, with the most relevant Tri-Reforming conditions outlined below:

[0067] SU: This is the startup condition with 850 C, 20 bar, and with gradual transition from a 32% CH4 / 64% H2O composition to a 47% CH4 / 47% H2O. Essentially, this is a steam-methane reforming condition which is expected to yield a high H2 / CO product ratio much greater than 2. The GHSV started at 7909 and ended at 15,804 1 / hr.

[0068] la: this condition was 940C, 20 bar, 20.9% Ci, 15.2% CO2, 10.45% CO, 48.56% H2O. This is an example of the “partially-oxidized” gas described above. The GHSV was set at about 15,700 1 / hr.

[0069] lb. this condition is the same as la except GHSV is 23,600 1 / hr.

[0070] 2a. this condition is the same as la except pressure in increased to 27.5 bar and GHSV is 15,700 1 / hr

[0071] 2b. this condition is the same as 2a except GHSV is 23,600 1 / hr.

[0072] The results of two different catalysts are shown in FIGS. 7-10. Specifically, the %Ci conversion, %CO2 conversion, and product H2 / CO are noted. The data between 400 hr and800 hr is omitted since the test conditions were different and not pertinent to Tri-Reforming. The final test condition is a repeat test of condition lb to test whether the catalyst has exhibited any performance degradation or hysteresis.

[0073] Both catalysts (Ni / W on alumina and Ni on Ca / Mg Oxide) showed > 95% Ci conversion and about 10% CO2 conversion while achieving a product H2 / CO of just under 2. With integration of the electrolyzer cathode stream, it is anticipated that the final H2 / CO of the syngas will be H2 / CO > 2. In FIGS. 7 and 9, the upper set of values are % Ci conversion, while the lower set of values are % CO2 conversion.

[0074] The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms, and can also be used in any appropriate combination. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Claims

CLAIMS1. A method for integrating tri-reforming and water or steam electrolysis in a system, comprising the steps of: reacting methane, CO2, H2O, and O2 in a methane tri-reformer (TRM) to form syngas, the syngas including H2 and CO; performing electrolysis of water or steam in an electrolyzer to produce H2 at a cathode of the electrolyzer and O2 at an anode of the electrolyzer; and providing at least some of the O2 generated by the electrolyzer to the TRM for use as a reactant to form the syngas.

2. The method of claim 1, comprising combining the H2 produced by the electrolyzer with the syngas produced by the TRM to adjust a ratio of H2 to CO in the syngas.

3. The method of claim 1, wherein a stream of CO2 provides at least some of the CO2 to the TRM; a portion of the stream of CO2 is provided to an anode of the electrolyzer; and the O2 at the anode is combined with the portion of the CO2 stream and fed to the TRM.

4. The method of claim 1, comprising pumping a stream of H2O and providing a first portion of the stream of H2O to the TRM and a second portion of the stream of H2O to an anode of the electrolyzer; and O2 at the anode is combined with the portion of the H2O and fed to the TRM.

5. The method of claim 1, comprising using a stream of CO2 as a sweep gas for an anode of the electrolyzer; wherein O2 at the anode is combined with the stream of CO2, wherein a first portion of the combined stream is fed to an oxy-combustion process to burn CH4; and a second portion of the combined O2 and CO2 is fed to the TRM.

6. The method of claim 1, comprising reacting the hydrocarbon with H2O in a prereforming reactor upstream of the TRM to partially convert a heavy hydrocarbon to Ci, CO, CO2, and H2; combining the Ci, CO, and CO2 and H2 at the outlet of the pre-reforming reactor with the CO2 and O2 to form a gas combination; and providing the gas combination to the TRM.

7. The method of claim 1, comprising receiving syngas in a methanol (MeOH) synthesis reactor from the TRM; and providing CO2 from the MeOH synthesis reactor to the TRM.

8. The method of claim 1, comprising: providing the syngas to a hydroformylation reactor, and reacting the syngas and an unsaturated hydrocarbon feed in the hydroformylation reactor to produce an aldehyde; providing the aldehyde and H2 produced by the cathode of the electrolyzer to a hydrogenation reactor; and reducing the aldehyde to produce an alcohol in the hydrogenation reactor using the H2.

9. A system, comprising: a methane tri-reformer (TRM) configured to react methane, CO2, H2O, and O2 to form syngas, the syngas including H2 and CO; andan electrolyzer configured to electrolyze H2O to produce H2 at a cathode of the electrolyzer and O2 at an anode of the electrolyzer, wherein the TRM and the electrolyzer are integrated such that the O2 generated at the anode is provided to the TRM.

10. The system of claim 8, wherein the TRM and the electrolyzer are integrated such that the H2 generated at the cathode can be utilized to adjust a ratio of H2 to CO in the syngas.

11. The system of claim 8, wherein the electrolyzer is a solid oxide electrolysis cell (SOEC).

12. The system of claim 8, wherein the electrolyzer is a polymer electrolyte membrane (PEM) electrolyzer.

13. The system of claim 8, comprising a compressed CO2 flow path configured to provide CO2 as a sweep gas to the anode of the electrolyzer such that the O2 and CO2 sweep gas are provided in combination to the TRM from the electrolyzer.

14. The system of claim 8, comprising a steam flow path configured to provide steam as a sweep gas to the anode of the electrolyzer such that the O2 and steam sweep gas are provided in combination to the TRM from the electrolyzer.

15. The system of claim 8 further including a pre-reforming reactor upstream of the TRM.

16. The system of claim 8, comprising a hydroformylation reactor configured to receive the syngas from the TRM and to generate aldehydes from the syngas and an unsaturated hydrocarbon feed, and a hydrogenation reactor downstream of the hydroformylation reactor configured to convert the aldehydes to alcohols, wherein the hydrogenation reactor is integrated with the electrolyzer such that the hydrogenation reactor receives H2 produced at the cathode of the electrolyzer.

17. The system of claim 8, comprising a methanol synthesis reactor integrated with the TRM, wherein the methanol synthesis reactor is configured to convert the syngas to methanol and wherein the TRM is configured to receive a tail gas comprising CO2 form the methanol synthesis reactor.

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