CN1206689A - Method for preparing hydrogen from solid electrolyte membrane - Google Patents
Method for preparing hydrogen from solid electrolyte membrane Download PDFInfo
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- CN1206689A CN1206689A CN 98114838 CN98114838A CN1206689A CN 1206689 A CN1206689 A CN 1206689A CN 98114838 CN98114838 CN 98114838 CN 98114838 A CN98114838 A CN 98114838A CN 1206689 A CN1206689 A CN 1206689A
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Abstract
A process for producing synthesis gas and hydrogen by passing a compressed and heated oxygen-containing gas mixture into a reactor having at least one solid electrolyte oxygen ion transport membrane to separate transported oxygen. Organic fuel reacts with the oxygen to form synthesis gas. The resulting synthesis gas is separated into hydrogen gas through at least one solid electrolyte hydrogen transport membrane to separate the transported hydrogen in the same or different separator.
Description
The present invention relates to the production of hydrogen gas using a solid electrolyte membrane, and more particularly, to the production of hydrogen gas by first forming synthesis gas using a solid electrolyte ion transport membrane and then separating the hydrogen gas using another solid electrolyte membrane.
U.S. patent application entitled "method for producing oxidation products and generating energy using a solid electrolyte membrane in conjunction with a turbine" (water flow No.,attorney Docket No. D-20215, also incorporated herein by reference) is incorporated herein by reference.
Solid electrolyte ionic or mixed conductor ion transport membranes have been used to extract oxygen from gases at temperatures of about 500-1200 ℃. The optimum operating temperature for gas migration depends on the membrane itself, and in particular the materials that make up the membrane. The ionic conductivity is also a function of the operating temperature, and it also increases as the operating temperature increases. In addition to the lower conductivity of ion transport membranes at operating temperatures below about 500 ℃, surface kinetic limitations on the membrane may also restrict the oxygen flux, i.e., the amount of oxygen per unit area of time.
Operating temperatures greater than about 1200 c for ion transport membranes are also undesirable because of the increased material and structural constraints (e.g., seals, manifolds, thermal stresses) that are imposed at high temperatures.
One of the most attractive features of an oxygen ion transport membrane system is that the membrane has infinite selectivity for oxygen transport, and that oxygen transport is driven by the ratio of oxygen activities on both sides of the membrane. It is therefore possible for a higher oxygen flow to occur in the case of a reaction on the anode side. It is also possible to simultaneously transfer oxygen from a low pressure oxygen-containing gas stream to a high pressure reaction environment.
At high temperatures, the oxygen ion transport material contains mobile oxygen ion vacancies that provide conduction sites for the selective transport of oxygen ions through the material. When oxygen ions flow from the side with a high oxygen partial pressure to the side with a low oxygen partial pressure, the migration is driven by the partial pressure difference across the membrane. Ionization of oxygen molecules into oxygen ions occurs at the cathode side of the membrane. And oxygen ions subsequently migrate across the ion transport membrane. The oxygen ions are deionized at the anode side of the membrane to again form oxygen molecules. For materials that exhibit only ionic conductivity, the outer electrode may be placed on the surface of the electrolyte and the current placed in the external circuit. In "mixed conducting" materials, electrons migrate internally to the cathode, thus completing the circuit and obviating the need for external electrodes. The two-phase conductor in which the oxygen ion conductor and the electron conductor are mixed is a mixed conductor.
Partial oxidation reactions involving carbonaceous feed materials ('PO')x") and/or steam reforming reactions are conventional methods for producing synthesis gas. Synthesis gas and its main components, carbon monoxide, and hydrogen are useful industrial gases and are important precursors for the production of chemicalsSuch chemicals include ammonia, alcohols (including methanol and higher alcohols), synthetic fuels, acetic acid, aldehydes, ethers, and the like. Feed stocks including natural gas, coal, petroleum, and fuel oil are commonly used to produce synthesis gas through partial oxidation and steam reforming reactions. These reactions can be represented by the following scheme:
in the formula CmHnIs the hydrocarbon feed.
In order to improve the reaction rate and selectivity of certain products, external catalysts in the form of fixed or fluid beds, or multiple catalyst tubes, may be used. The individual synthesis gas components, particularly hydrogen and carbon monoxide, can be obtained using a number of conventional gas separation processes known in the art, such as those based on pressure swing adsorption, temperature swing adsorption, polymer membranes, and cryogenic distillation. By reacting CO in the synthesis gas with steam ( ) Convert it to CO2And H2Thereby performing the water gas shift reaction to increase the hydrogen production.
Conventional partial oxidation processes often use molecular oxygen produced by conventional gas separation processes that typically operate at temperatures below 100 ℃. Since the partial oxidation reaction itself typically requires high temperature operation at temperatures above 800 ℃. Integration between partial oxidation and conventional oxygen separation has not previously been appreciated. As a result, conventional partial oxidation reactions are often characterized by low feed conversion, low hydrogen to carbon monoxide ratios, and low hydrogen and carbon monoxide selectivities. In addition, the external supply of oxygen typically required in partial oxidation reactions significantly increases capital and operating costs, which can reach as much as 40% of the total synthesis gas production cost. Also, since a large amount of carbon monoxide gas is generated in the partial oxidation reaction, when only hydrogen gas is required as a final product, the product requires two alternate conversions, which results in low efficiency. Alternate conversions also increase process costs.
Steam reforming reactions are also used for synthesis gas generation. The process is for hydrogen and has a high H content compared to partial oxidation reactions due to the greater hydrogen production per mole of organic fuel produced by the steam reforming process2The production of mixtures with a/CO ratio (for example, a ratio greater than 2) has further advantages. However, the steam reforming reaction is an endothermic reaction requiring a large amount of heat energy, and thus, when H is used2At a/CO ratio below 2, the process is less attractive for the production of synthesis gas.
In the past, developments in the field of oxygen ion transport membrane systems have included integrating the membrane system with a steam turbine. US5516359, 5562754, 5565017, and EP00658366 disclose the production of oxygen in combination with a steam turbine system. Commonly licensed U.S. patent application 08/490362 entitled "method for producing oxygen and generating power with a solid electrolyte membrane integrated with a steam turbine" also relates to the production of oxygen with an ion transport membrane system integrated with a steam turbine. And which is incorporated herein by reference.
U.S. Balachandran et al, "purification and Characterization of Densseramic Membranes for Partial Oxidation of Methane", Proc. of Coaliquection and Gas Conversion controller' review of the conference, Pittsburgh, PA (aug. 29-31, 1995) and "Dense Ceramic Membrane for Converting Methane to Syngas" (submitted on Frist International conference Ceramic Membranes), 188th recording to the electrochemical facility, Inc., Chicago IL (Oct. 8-13, 1993) disclose oxygen ion transport membrane materials for synthetic Gas production. US5306411(Mazanec et al) discloses a process combining oxygen separation with partial oxidation (for synthesis gas production) or oxidative coupling of methane.
Apart from the technological advances that have occurred in relation to ion transport membrane systems, the applicant is unaware of any technical content of the practical integration of an ion transport membrane system based on synthesis gas production and a hydrogen separation system, and also the separation process thereof, in one and the same unit, using a solid electrolyte ion transport membrane.
It is therefore an object of the present invention to provide an integrated process for oxygen ion transport based synthesis gas production and hydrogen separation using a hydrogen transport membrane, such as a palladium or palladium-alloy or proton transport membrane based process.
It is another object of the present invention to provide a process wherein the partial oxidation reaction and the steam reforming reaction can be carried out together to achieve a near energy neutral configuration.
It is a further object of the present invention to provide an improved, economically attractive, flexible and highly thermally efficient process for the production of synthesis gas.
It is yet another object of the present invention to balance the heat of reaction by using a large amount of oxygen-containing gas (usually air) as a heat sink on the cathode side of the oxygen ion transport membrane.
It is another object of the invention to achieve gas inlet and inlet temperatures below the reaction temperature by counter-flowing the anode side reactant gas into the cathode side oxygen-containing gas stream (typically air).
It is yet another object of the present invention to increase the conversion of organic fuel to anode side synthesis gas by removing hydrogen from the synthesis gas conversion zone using an ion transport membrane.
The present invention relates to a process for the production of hydrogen and synthesis gas. The process includes passing a compressed and heated oxygen-containing gaseous mixture to an oxygen reactor having at least one solid electrolyte oxygen ion transport membrane. The reactor has a first zone and a second zone separated by an oxygen ion transport membrane. At least a portion of the oxygen in the mixture migrates across the oxygen ion transport membrane from the first zone to the second zone to react with the purge gas stream containing the gaseous organic fuel while forming an oxygen-depleted retentate gas stream in the first zone. The purge gas stream is passed into the second zone to react with the migrating oxygen to form synthesis gas. Synthesis gas is directly contacted with at least one hydrogen transport membrane to produce a high purity hydrogen permeate and a hydrogen-depleted synthesis gas retentate. The high purity hydrogen permeate is then discharged as a hydrogen product.
Another embodiment includes the step of passing the compressed and heated oxygen-containing gaseous mixture to an oxygen reactor having at least one solid electrolyte oxygen ion transport membrane. The reactor has a first zone and a second zone separated by an oxygen ion transport membrane. At least a portion of the oxygen in the mixture migrates across the oxygen ion transport membrane from the first zone to the second zone to form an oxygen-depleted retentate gas stream in the first zone. Mixing a gaseous organic fuel, steam, and optionally CO2And passed into the second zone to react with the migrating oxygen to form synthesis gas. Steam and CO passing into the second zone can be controlled2In order to vary the amount of H in the resulting synthesis gas stream2The ratio of/CO. The synthesis gas stream in the second zone is withdrawn and passed to a third zone in a hydrogen separator having at least one solid electrolyte hydrogen transport membrane. The hydrogen separator has a third region and a fourth region separated by a hydrogen transport membrane. At least a portion of the hydrogen migrates across the hydrogen transport membrane from the third zone to the fourth zone, thereby producing a hydrogen permeate in the fourth zone and a hydrogen-depleted synthesis gas in the third zone. The hydrogen permeate is discharged from the fourth zone as hydrogen product. The hydrogen separation process is selected to operate at the same or slightly lower temperature than the oxygen ion transport membrane.
In yet another embodiment, the compressed and heated oxygen-containing gaseous mixture is passed to an oxygen reactor having at least one solid electrolyte oxygen ion transport selective membrane and at least one solid electrolyte hydrogen transport membrane. The reactor has a first zone, a second zone, and a third zone. At least a portion of the oxygen in the mixture migrates across the oxygen ion transport membrane from the first zone to the second zone to provide a first oxygen permeate stream for reaction with a purge gas stream containing a gaseous organic fuel while forming an oxygen-depleted retentate gas stream. The purge gas stream is passed into the second zone to react with the migrating oxygen to form synthesis gas. The synthesis gas is directly contacted with at least one hydrogen transport membrane to produce a high purity hydrogen permeate in the third zone and leave a hydrogen-depleted synthesis gas retentate in the second zone. The hydrogen permeate is then withdrawn from the third zone as a hydrogen product. One of the advantages of removing hydrogen from the synthesis gas conversion zone is that it maintains a favorable equilibrium driving the reaction through.
In some embodiments, the oxygen-containing gaseous mixture is heated by indirect heat exchange (at least in part) with at least one gaseous stream comprising the oxygen-depleted retentate gas in the first zone, the hydrogen-depleted retentate synthesis gas in the hydrogen separator, and the hydrogen permeate gas.
Herein, the term "reactor" refers to a reactor in which the migrating oxygen undergoes a chemical reaction and thus consumes the oxygen.
Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings. Wherein:
FIG. 1 is a schematic diagram showing a system for producing hydrogen and synthesis gas according to the present invention, wherein the synthesis gas is formed due to the migration of oxygen ions in an oxygen reactor and hydrogen is formed due to a hydrogen migration membrane in a hydrogen separator;
FIG. 2 is a schematic diagram showing a system for producing hydrogen and synthesis gas according to the present invention in which oxygen permeates through an oxygen ion transport membrane to form synthesis gas and hydrogen in the synthesis gas permeates through a hydrogen transport membrane to form hydrogen, wherein both membranes will be found in one reactor.
The invention can be accomplished by a hydrogen production process in which oxygen in an oxygen-containing gas, such as air, is separated using a solid oxygen ion transport membrane and the separated oxygen is utilized in a partial oxidation reaction and optionally a steam reforming reaction of a carbonaceous feed. The partial oxidation and/or steam reforming reactions produce synthesis gas for forming hydrogen from the hydrogen transport film.
Fuel oxidation at the anode side of an oxygen ion membrane reactor reduces the partial pressure of oxygen at the membrane on that side. This increases the driving force of the oxygen reactor, resulting in higher oxygen flow and lower membrane area requirements. These benefits occur even when the oxygen-containing feed gas is at a lower pressure and the fuel side is at a higher pressure, so the system requires less power. The partial oxidation reaction (an endothermic reaction) and the steam reforming reaction (an exothermic reaction) can be carried out in one reactor to obtain an almost energy neutral system. In addition, a large number of heat sinks in the form of oxygen-containing gas (typically air) allow for further balancing the heat of reaction and controlling the temperature of the reaction zone. In another embodiment, the partial oxidation reaction and the steam reforming reaction are carried out in separate ion transfer reactors. The final synthesis gas produced from the oxygen ion transport reactor by the partial oxidation reaction and/or the steam reforming reaction is then fed into the hydrogen membrane transport reactor. Preferably, the oxygen-containing gas and the reaction fuel are countercurrent to each other. By passing the fuel and oxygen-containing gas streams into the reactor at low temperatures and relying on heat exchange properties, it is possible to maintain critical components of the reactor, such as seals and structural components at reactor gas inlet and outlet locations, at suitable temperatures for ease of mechanical design and reduced manufacturing costs.
Oxygen ion transport membranes are used to separate oxygen from an oxygen-containing gas stream and materials that conduct oxygen ions and electrons are described herein as "mixed conductor oxides" or "mixed conductors". It is now known that there are a number of potentially rich mixed conductors in the fluorite and perovskite crystal structures. Table I is a partial catalog of hybrid conductors for oxygen production.
Table I: hybrid conductor
Although mixed or two-phase conductors are preferred for use in pressure-driven ion transport reactors, the present invention also does not use electrically driven ion transport membranes. Typically, the ion-driven membrane may be in the form of a dense membrane, or a thin membrane loaded on a porous substrate. The thickness of the film is typically less than about 5000 microns, preferably less than 100O microns, most preferably less than 100 microns. The ion transport membrane may be in the form of a tube or a flat plate.
Similarly, hydrogen transport membranes are used to separate hydrogen from the synthesis gas stream. A number of hydrogen separation units using any of several high temperature hydrogen technologies may be employed, such as hydrogen permeable solid membranes, for example membranes based on palladium or palladium-alloys or proton conductors. Preferably, a proton conductor is used. Table II is a partial catalog of hydrogen conductors that may be beneficially used for hydrogen separation.
Table II: high temperature proton conductor (note: here'd' is oxygen defect per unit chemical formula)
The method of the present invention may be described with the schematic illustration of the system 50 of fig. 1. A process configuration for producing synthesis gas and hydrogen using ion transport technology is given in fig. 1. An oxygen-containing gas stream 1, preferably air, is compressed to a lower pressure by a blower 2 and then heated in a heat exchanger 3 by an oxygen-depleted retentate gas stream 8 before being passed through an optional heater 4 to an oxygen reactor 6 to produce a heated and compressed oxygen-containing gas stream 5. In one embodiment, stream 8 is discharged as an off-gas, while in another embodiment it is used as a nitrogen product stream. Stream 5 is fed to a first zone 40 of an oxygen ion transport membrane reactor 6 having a first zone 40 and a second zone 41 separatedby an oxygen ion transport membrane 7. The first zone 40 is here where the oxygen-containing gas 5 is fed and is referred to as the cathode or retentate side. Typically, the pressure in the first region 40 is in the range of 1 to 40 atmospheres, preferably 1 to 10 atmospheres. In reactor 6, a portion of the oxygen of oxygen-containing gas stream 5 in first zone 40 is removed and exit gas stream 8 is an oxygen-depleted gas stream. The oxygen ion conductivity of the membrane is typically 0.01 to 100S/cm, where "S" is 1/ohm. Oxygen migrates through the membrane 7 into a second region 41, the second region 41 being referred to as the permeate or anode side, where oxygen is scavenged by reaction using a gas mixture 9 containing an organic fuel 10. If liquid carbonaceous fuel is used to produce hydrogen, it must be vaporized before entering the reactor. The pressure of the second region 41 is typically 1-100 atmospheres. Preferably 1-10 atmospheres. In one embodiment the organic fuel is a carbonaceous fuel, preferably methane or clean burning natural gas. They are optionally pressurized in compressor 11 and preferably further heated in heater 12 while being mixed with steam or atomized water 13, and a recycle permeate gas stream 14 from a hydrogen transport membrane separator 16.
Although hydrogen separation is performed here using a hydrogen transport membrane, other separation schemes known to those skilled in the art, such as pressure swing adsorption, temperature swing adsorption, cryogenic gas separation, polymer membranes for gas separation, may also be used.
The steam or atomized water added to the fuel gas stream facilitates the steam reforming process and increases the hydrogen concentration in the synthesis gas 15. This is because steam reforming generally produces a greater amount of hydrogen than partial oxidation processes. For example, if methane is used as the fuel, steam reforming provides 50% more hydrogen than the partial oxidation process.
The steam reforming process is typically an endothermic process, while the partial oxidation process is an exothermic process. The partial oxidation reaction and the steam reforming reaction may be carried out separately or simultaneously using a suitable catalyst, depending on the thermal requirements and thermal transfer characteristics of the system. As a result, the simultaneous use of the partial oxidation process and the steam reforming process facilitates an ion transport system that achieves "energy neutralization". Wherein the exothermic nature of the partial oxidation process provides efficient energy for the steam reforming process. This also facilitates a method of obtaining heat self-sustaining. As previously discussed, heat sinks in the form of large volumes of oxygen-containing gas (typically air) can further suppress the reaction temperature.
At typical ion transport membrane operating temperatures, the partial pressure of oxygen in the oxygen-depleted gas stream is low. The low partial pressure facilitates rapid oxygen transfer across the oxygen ion transport membrane. Even when the pressure of the oxygen-containing gas is low, driven by oxygen migration due to the difference in oxygen activity on both sides of the membrane. This feature of the reactor ensures that oxygen is removed at lower power requirements.
The partial pressure of oxygen may be increased in order to increase the oxygen flux through the oxygen transport membrane. For example, if air is used as the oxygen-containing feed gas and nitrogen is required at high pressure, it is advantageous to compress the air. Similarly, if nitrogen is not required as a product at high pressure, compressing air may be undesirable. The retentate stream may be expanded to recover some of the compression or combusted in a steam turbine to produce electricity. If power generation is desired, the oxygen-containing gas (usually air) should be compressed to the pressure of a typical turbine inlet (100-. At the same time, if nitrogen is not required as a product, it may be advantageous to compress the oxygen-containing gas (typically air) only to the pressure required to compensate for the change in pressure loss in the reactor.
Under typical operating conditions of an oxygen ion transport membrane reactor, the fuel gas undergoes a partial oxidation reaction to produce synthesis gas (hydrogen and carbon monoxide) and various other constituents including carbon dioxide, water and other minor constituents such as higher hydrocarbons. A catalyst may be used in the second zone of the reactor to promote the desired partial oxidation and steam reforming reactions.
The external catalyst used to promote the partial oxidation/steam reforming reaction can be arranged in a variety of ways, including deposition on a moving membrane, a fixed bed, a fluidized bed, a catalyst rod or tube. For example, a partial oxidation catalyst may be used on the surface of an oxygen ion transport membrane, while a steam reforming catalyst is used in the form of a fixed bed. Different catalysts may be used for the partial oxidation reaction and the steam reforming reaction, and the extent of the reaction is controlled by mixing the respective catalysts in an appropriate ratio as will be appreciated by the skilled artisan. For example, a layered bed of partial oxidation and steam reforming catalysts (e.g., NiO-based catalysts) may be used to control the carbon monoxide to hydrogen ratio in the synthesis gas. Removing steam and CO from the gaseous phase2Can also be used to control the carbon monoxide/hydrogen ratio in the synthesis gas.
As further shown in FIG. 1, fuel 10 undergoes a partial oxidation reaction in second zone 41 of reactor 6, thereby forming synthesis gas 15 in reactor 6. Optionally, the synthesis gas 15 may be removed and recovered. The stream of synthesis gas 15 may then be fed to a second downstream hydrogen membrane separator 16. If the operating temperature of the hydrogen transport membrane is lower than the operating temperature of the oxygen ion conductive membrane, it may be necessary to adjust the temperature of the synthesis gas stream.
As in the oxygen ion membrane reactor 6, the hydrogen separator 16 is also partitioned into a third zone 42 and a fourth zone 43, zone 42 being referred to as the hydrogen retentate side or cathode side and zone 43 preferably being the hydrogen permeate side or anode side. The third zone 42 and the fourth zone 42 are separated by at least one hydrogen transport membrane 30.
The hydrogen gas permeates through at least one hydrogen transport membrane 30 of the hydrogen separator 16. The final hydrogen stream 17 formed in the fourth zone 43 of the separator 16 may enter the heat exchanger 3 to transfer heat to the upstream oxygen containing gas stream 1.
It is important to maintain a high pressure of the synthesis gas in order to maintain the necessary hydrogen partial pressure difference across the hydrogen transport membrane. In this arrangement, the compressor 11 may compress the fuel gas to provide the desired conditions for the reaction in the second zone 41 and to provide the necessary hydrogen partial pressure to the second zone 41 to effectively migrate hydrogen downstream. Preferably, a pressure of about 10-50 atmospheres is provided.
The carbon monoxide rich gas stream 18 exiting the third zone 42 is preferably used to heat the oxygen containing gas stream 1 in heat exchanger 3. Further recovery of hydrogen from the retentate stream 18 may be accomplished in a further reactor 19, leaving a carbon monoxide rich stream 21. The separation thus provides a hydrogen stream 20 for addition to hydrogen stream 17.
The downstream hydrogen recovery process may be carried out in separator 19 at low temperatures using conventional methods known in the art such as pressure swing adsorption, thermal swing adsorption, polymer membranes, and cryogenic distillation; or the recovery process is carried out at elevated temperatures, for example using a hydrogen-transporting solid membrane, such as a membrane based on palladium or palladium-alloy or an electrically or pressure driven proton conductor membrane. It should be noted that: if proton-conducting membranes are used for hydrogen separation, electrodes and an external circuit are required for the electric drive method. Pressure-driven hydrogen separation can be performed in situ if the hydrogen transport membrane has sufficient electronic conductivity. The choice of the downstream hydrogen separation process depends onThe pressure and purity of the hydrogen and carbon dioxide gases are required. For example, a polymer membrane process will produce a slightly impure hydrogen stream (90-96%) at low pressure and a purer carbon dioxide at high pressure, whereas a pressure swing adsorption separation of a high temperature synthesis gas mixture will produce a purer hydrogen stream (96-99.9%) at high pressure and an impure carbon dioxide at low pressure. Palladium-based or proton-conducting membranes allow the production of H of very high quality due to their infinite selectivity for hydrogen migration2And (4) air flow.
The concentration of hydrogen in the carbon monoxide-rich gas stream can be adjusted using certain operating parameters, for example, changing the hydrogen partial pressure difference across the hydrogen transport membrane. Similarly, various parameters associated with the hydrogen transport membrane may also be adjusted, such as changing the thickness and area of the membrane.
Carbon monoxide in the carbon monoxide rich stream 21 can be recovered with a separator 22 to form a carbon monoxide rich stream 23. The residual spent carbon monoxide stream 14 may optionally be purged as an off-gas stream 24 or recycled for mixing with the organic fuel stream 10 into the oxygen ion transport reactor 6.
If carbon monoxide is not desired as a product, it can be used as a fuel to provide heat input at various stages of the process. For example, it can be used in a waste heat boiler to generate the steam required for the process.
Also, if carbon monoxide is not desired as a product, it can be converted to carbon dioxide to increase the production of hydrogen by the water-gas shift reaction. Optionally, the carbon monoxide may also be combusted to provide the heat required at different locations in the system. Carbon monoxide can also be combusted in a steam turbine associated with the present system to generate electricity.
Another aspect of the present invention is shown in system 250 of fig. 2. In this solution, the oxygen ion transport membrane reactor and the hydrogen separator are combined in a single unit. The system ensures that oxygen separation, synthesis gas formation, and hydrogen separation are performed in the same membrane unit while providing improved equilibrium conditions in the reactor.
An oxygen-containing gas stream (preferably air) 201 is compressed to a higher pressure by blower 202 and then heated in heat exchanger 203 by waste gas stream (or nitrogen product) 208. And then passed into optional reactor 204 to form heated and compressed oxygen-containing gas stream 205. Stream 205 is fed to a first zone 240 of an oxygen ion transport membrane reactor 206 having a first zone 240 and a second zone 241 separated by an oxygen ion transport membrane 207. Here, the first zone is where the oxygen-containing gas 205 is fed, otherwise referred to as the oxygen cathode or oxygen retentate side. In reactor 206, a portion ofthe oxygen containing gas in first zone 204 is removed and vent stream 208 is a nitrogen rich stream. The oxygen migrates through the membrane 207 into the second region 241, otherwise referred to as the permeate side or anode side, where it is scavenged by the gas mixture 209 containing the organic fuel 210.
Under the typical operating conditions of an ion transport membrane reactor, the fuel gas undergoes partial oxidation to produce synthesis gas and various other components including carbon dioxide, water, and other hydrocarbons. Catalyst may be introduced into the second region 241 of the reactor 206.
The purge gas 209 is a carbonaceous fuel, preferably methane or natural gas. The purge gas 209 is preferably pressurized in a compressor 211 and further optionally heated in a heater 212 and mixed with steam or atomized water 213, recycled and discharged synthesis gas stream 214.
At typical ion transport membrane operating temperatures, the partial pressure of oxygen in the purge gas stream is low, typically less than 10-10 atmospheres, which facilitates rapid oxygen transport through the oxygen ion transport membrane and allows for lower compression of the oxygen containing gas stream. This feature of the reactor ensures that oxygen is transferred at lower power requirements.
Another purge gas 226 is optionally used to remove permeated high purity hydrogen from the third zone 242. The purge gas 226 may be a gas that is easily separated from hydrogen, such as steam or N2. Preferably, the purge gas 226 is pressurized in a compressor 227 and further optionally heated in a heater 228.
The material formed in reactor 206 by the partial oxidation reaction of fuel 210 in second region 241 is carbon monoxide rich gas stream 218 that can be removed and recovered. Stream 218 can be used to provide heat to oxygen containing stream 201 in heat exchanger 203. Further hydrogen recovery may be provided as stream 218 passes through separator 219. Forming a carbon monoxide rich gas stream 221 and a separated hydrogen stream 220. The recovery of the carbon monoxide gas stream 221 is performed in a carbon monoxide separation unit 222, thereby producing pure or nearly pure carbon monoxide 223. An extracted off-gas stream 214 is formed in carbon monoxide separation unit 222 and is optionally purged as off-gas stream 224.
A hydrogen-rich gas stream 217 is formed in a third region 242 of reactor 206 by heat exchanger 203. The hydrogen-rich gas stream 220 separated from the carbon dioxide-rich gas stream 218 in separator 219 is then mixed with the hydrogen-rich gas stream 217 to form hydrogen-rich gas stream 229.
The system provided by the solution of figure 2 also promotes the formation of synthesis gas in greater quantities. Because the hydrogen is separated in situ, the hydrogen partial pressure is reduced in the partial oxidation reaction. Thus, by moving the partial oxidation/steam shift reaction even further to the product side, Le Chatelier's rules even favor synthesis gas formation. By introducing the organic fuel into the second zone at high pressure, hydrogen gas is formed at a sufficiently high pressure to drive the hydrogen gas through the hydrogen transport permeable membrane. In addition, the purge gas may be used to effect hydrogen separation in a solution that uses separate oxygen and hydrogen separators. For example, steam may be used as a purge gas in the hydrogen separator, since steam is easily separated from hydrogen by condensation.
If the conversion is incomplete in the reactor, the purge gas stream will contain unreacted fuel, wherein at least a portion of the gas stream may be recycled into the reactor, preferably after removal of hydrogen and carbon monoxide.
Various other features of the solution of fig. 1 described above are also applicable to the solution of fig. 2 and will be appreciated by a person skilled in the art. Various functions, such as heat exchange in heat exchanger 3 or 203, may be incorporated into Reactor 6 or 206, as disclosed in U.S. patent application serial No. entitled "SELIC Reactor Design," which is incorporated herein by reference.
It is contemplated that the present invention may be further extended by the use of the products obtained by the present invention. For example, the separated hydrogen-rich gas stream and nitrogen-rich gas stream produced by the present invention may be used in the production of ammonia. In addition, the synthesis gas produced by the present invention is a valuable industrial product that can be used in fuel compartments or for the production of chemicals such as methanol, acetic acid, dimethyl ether, acetonitrile, formaldehyde. Thus, the production of synthesis gas may be combined with a down-stream process, optionally with adjustment of the hydrogen/carbon monoxide ratio.
Particular features of the invention are shown in one or more of the drawings for convenience only, but each feature may be combined with other features of the invention. Those skilled in the art will recognize additional solutions and they are also included within the scope of the claims.
Claims (10)
1. A process for producinghydrogen and synthesis gas comprising the steps of:
(a) passing a compressed and heated oxygen-containing gaseous mixture into an oxygen reactor comprising at least one solid electrolyte oxygen ion transport membrane, said reactor having a first region and a second region separated by said oxygen ion transport membrane, wherein at least a portion of the oxygen in said mixture migrates across said oxygen ion transport membrane from said first region into said second region, forming a first permeate gas stream in said second region to react with a purge gas stream comprising a gaseous organic fuel while forming an oxygen-depleted retentate gas stream in said first region;
(b) passing said purge stream into said second zone to react with said migrated oxygen to form synthesis gas in said first permeate stream;
(c) contacting said first permeate gas stream directly with at least one hydrogen transport membrane to produce a high purity hydrogen permeate and a hydrogen-depleted synthesis gas retentate; and
(d) the high purity hydrogen permeate is discharged as a hydrogen gas stream product.
2. The process of claim 1 further comprising a hydrogen separator having said hydrogen transport membrane and a conduit for passing said first permeate gas stream to said hydrogen separator.
3. The process of claim 1 wherein said oxygen-containing gaseous mixture is heated in heat exchange relationship with at least one of said oxygen-depleted retentate gas in said first zone, said hydrogen-depleted synthesis gas retentate in said hydrogen separator, and said hydrogen permeate gas.
4. The method of claim 1 wherein said gaseous phase organic fuel consists of an organic fuel treated with steam or atomized water.
5. A method of producing hydrogen comprising the steps of:
(a) passing the compressed and heated oxygen-containing gaseous mixture into an oxygen reactor comprising at least one solid electrolyte oxygen ion transport membrane, said reactor having a first region and a second region separated by said first oxygen ion transport membrane, wherein at least a portion of the oxygen in said mixture migrates across said oxygen ion transport membrane from said first region into said second region to provide a first oxygen permeate gas stream which is then reacted with a purge gas stream comprising a gaseous organic fuel, while forming an oxygen-depleted retentate gas stream in said first region;
(b) passing said purge stream into said second zone to react with said migrated oxygen to form synthesis gas;
(c) withdrawing said first permeate gas stream from said synthesis gas stream in said second zone and passing into a third zone of a hydrogen separator comprising at least one solid electrolyte hydrogen transport membrane, said hydrogen separator having said third zone and a fourth zone separated by said hydrogen transport membrane, wherein at least a portion of said synthesis gas passes through said hydrogen membrane to migrate from said third zone to said fourth zone, thereby producing a hydrogen permeate in said fourth zone and a hydrogen-depleted synthesis gas in said third zone;
(d) said hydrogen permeate is removed from said fourth zone as a hydrogen stream product.
6. The process of claim 5 wherein the temperature of said synthesis gas stream is optionally reduced prior to passing to said hydrogen separator.
7. The process of claim 5 wherein said mixture is heated at least in part by indirect heat exchange with at least one of said oxygen-depleted retentate in said first zone, said hydrogen-depleted synthesis gas retentate in said third zone and said hydrogen permeate in said fourth zone.
8. A method of producing hydrogen comprising the steps of:
(a) the compressed and heated oxygen-containing gaseous mixture is passed into a membrane reactor comprising at least one solid electrolyte oxygen ion transport selective membrane and at least one solid electrolyte hydrogen ion transport membrane, said reactor having a first zone, a second zone, and a third zone. Wherein at least a portion of the oxygen in said mixture migrates through said oxygen ion transport membrane from said first region into said second region to form an oxygen-depleted retentate gas stream in said first region;
(b) passing a gaseous organic fuel into said second region to react with said migrated oxygen to form synthesis gas;
(c) contacting said synthesis gas directly with at least one hydrogen transport membrane to produce a high purity hydrogen permeate in a third zone and a hydrogen depleted synthesis gas retentate in said second zone;
(d) the hydrogen permeate is withdrawn from the third zone as a product hydrogen stream.
9. The process of claim 8 wherein said mixture is heated at least in part by indirect heat exchange with at least one of said oxygen-depleted retentate in said first zone, said hydrogen-depleted synthesis gas in said second zone, and said hydrogen permeate in said third zone.
The method of claim 8 wherein said gaseous organic fuel consists of an organic fuel treated with steam or atomized water.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98114838 CN1206689A (en) | 1997-04-29 | 1998-04-28 | Method for preparing hydrogen from solid electrolyte membrane |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US848200 | 1997-04-29 | ||
| CN 98114838 CN1206689A (en) | 1997-04-29 | 1998-04-28 | Method for preparing hydrogen from solid electrolyte membrane |
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| Publication Number | Publication Date |
|---|---|
| CN1206689A true CN1206689A (en) | 1999-02-03 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 98114838 Pending CN1206689A (en) | 1997-04-29 | 1998-04-28 | Method for preparing hydrogen from solid electrolyte membrane |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105584990A (en) * | 2016-02-29 | 2016-05-18 | 中国科学院工程热物理研究所 | Device for alternately preparing hydrogen |
| CN107021455A (en) * | 2015-12-22 | 2017-08-08 | 罗伯特·博世有限公司 | System and method and fuel cell for manufacturing hydrogen |
-
1998
- 1998-04-28 CN CN 98114838 patent/CN1206689A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107021455A (en) * | 2015-12-22 | 2017-08-08 | 罗伯特·博世有限公司 | System and method and fuel cell for manufacturing hydrogen |
| CN107021455B (en) * | 2015-12-22 | 2022-04-05 | 罗伯特·博世有限公司 | System and method for producing hydrogen and fuel cell |
| CN105584990A (en) * | 2016-02-29 | 2016-05-18 | 中国科学院工程热物理研究所 | Device for alternately preparing hydrogen |
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