KR19980081783A - Hydrogen Production Using Solid Electrolyte Membrane - Google Patents

Abstract

The present invention relates to a process for producing syngas and hydrogen by passing a compressed and heated oxygen containing gas mixture through a reactor having at least one solid electrolyte oxygen ion transport membrane to separate the transported oxygen. The organic fuel is reacted with oxygen to form synthesis gas. Hydrogen is separated by passing the resulting synthesis gas through one or more solid electrolyte hydrogen transport membranes for separating hydrogen transported in the same or different separators.

Description

Hydrogen Production Using Solid Electrolyte Membrane

The present invention relates to a method for producing hydrogen using a solid electrolyte membrane, and more particularly, a method for initially producing a synthesis gas using a solid electrolyte ion transport membrane, and separating hydrogen gas using another solid electrolyte membrane. It is about.

Solid electrolyte ion membranes or mixed conductor ion transport membranes have been used to extract oxygen from gases within temperatures of about 500 to about 1200 ° C. The optimum operating temperature for gas transport depends on the membrane itself, in particular on the material of the membrane. Ionic conductivity is also a function of operating temperature and increases as the working temperature rises. At operating temperatures below about 500 ° C., in addition to the low ion conductivity of the ion transport membrane, the surface kinetic limit on the membrane can also inhibit oxygen outflow, which is the amount of oxygen in the unit region per unit time.

Operating temperatures for ion transport membranes higher than about 1200 ° C. are also undesirable because the material and construction limitations (eg, sealing, manifolding and thermal stress) deteriorate at higher temperatures.

One of the most interesting features of the oxygen ion transport membrane system is the infinite selectivity of the membrane for oxygen transport and that oxygen transport is driven by the rate of oxygen activity on both sides of the membrane. Thus, high oxygen bleeding allows for reactions occurring on the anode side. It also enables oxygen transport from the low pressure oxygen containing stream to the high pressure reaction environment.

At elevated temperatures, the oxygen ion transport material contains mobile oxygen ion vacancy that provides an induction site for selective transport of oxygen ions through the material. The transport is induced by the difference in the partial pressure across the membrane, such as the flow of oxygen ions from the side with the higher partial pressure of oxygen to the side with the lower pressure of oxygen. After ionization of oxygen molecules to oxygen ions is performed on the cathode side of the membrane, oxygen ions are transported through the ion transport membrane. Oxygen ions are deionized at the anode side opposite the membrane, rebuilding oxygen molecules. For materials exhibiting only ionic conductivity, an external electrode can be disposed on the surface of the electrolyte, and electrical current is carried in the external circuit. In the mixed conducting material, the electrons are transported inside the cathode, thus completing the circuit and eliminating the need for an external electrode. Double conductors in which oxygen ion conductors are mixed with electron conductors are in the form of mixed conductors.

Partial oxidation reactions (POx) and / or steam formation reactions involving carbonaceous feedstocks are conventional methods for producing synthesis gas. Syngas and its main components, carbon monoxide and hydrogen, are useful industrial gases and are important precursors for producing chemicals including ammonia, alcohols (methanol and higher carbon alcohols), synthetic fuels, acetic acid, aldehydes and ethers, and the like. . Feedstocks, including natural gas, coal, gasoline and fuel oils, are commonly used to produce syngas by partial oxidation or steam reforming reactions. The reaction is as follows:

C _m H _n + m / 2 O ₂ = m CO + n / 2 H ₂ POx, exothermic

C _m H _n + m H ₂ O = CO + (m + n / 2) H ₂ SR, pyrogenic

CH is a hydrocarbon feedstock here.

In order to improve the reaction rate and selectivity of a particular product, an external catalyst in the form of a fixed bed or fluidized bed may be used. Individual syngas components, namely hydrogen and carbon monoxide, can be obtained using many conventional gas separation methods known in the art, such as pressure swing adsorption, temperature swing adsorption, polymerization membranes, and low temperature distillation. The water-gas replacement reaction can increase the yield of hydrogen by converting CO in the synthesis gas into H ₂ and CO ₂ by reaction with steam (CO + H ₂ O = CO ₂ + H ₂ ).

Conventional partial oxidation methods mainly utilize oxygen molecules produced by conventional gas separation processes that usually operate at temperatures below 100 ° C. In general, the integration between the partial oxidation reaction and conventional oxygen separation has not been realized in the past because the partial oxidation reaction itself requires a high temperature above 800 ° C. As a result, conventional partial oxidation reactions are often characterized by low feedstock conversion, low ratio of hydrogen to carbon monoxide, and low selectivity of hydrogen and carbon monoxide. In addition, the external oxygen supply typically required for partial oxidation reactions is significantly added to capital and operating costs, and may be as high as 40% of the total syngas production costs. In addition, when only hydrogen is needed as the final product, the large amount of carbon monoxide gas leading to the partial oxidation reaction product is inefficient because it requires a two-step transfer conversion.

Steam reforming reactions are also used to produce syngas. Since the steam reforming process produces more hydrogen per mole of organic fuel than the partial oxidation reaction, the process is more advantageous for producing a mixture with hydrogen and a high H ₂ / CO ratio (i.e. higher than 2). . However, steam reforming is an endothermic reaction that requires a significant amount of thermal energy, and therefore is not a good method for syngas production when the ratio of H ₂ / CO is less than 2.

In the past, advances in the area of oxygen ion transport membrane systems have included the combination of membrane systems with gas turbines. U.S. Pat.Nos. 5,516,359, 5,562,754, 5,565,017 and EPO 0,658,366 disclose the production of oxygen in a method integrated with gas turbine systems. US patent application Ser. No. 08 / 490,362, titled herein by reference to a method for generating oxygen and generating power using a solid dielectric film integrated with a gas turbine, also includes ion transport integrated with a gas turbine. It is associated with oxygen production using a membrane system.

Oxygen ion transport membrane material useful for syngas production. U. Balachandran et al., Fabrication and Characterization of Dense Ceramic Membranes for Partial Oxidation of Methane, Proc. of Coal Liquefaction and Gas Conversion Contractors' Review Conference, Pittsburgh, PA (Aug. 29-31, 1995) and Dense Ceramic Membranes for Converting Methane to Syngas, submitted to the First International Conference on Ceramic Membrnaes, 188th meeting to the Electrochemical Society, Inc., Chigo, IL (Oct. 8-13, 1995). U. S. Patent No. 5,306, 411 discloses a process involving oxygen separation with partial oxidation (for synthesis gas production) or oxidative coupling of methane.

Despite recent technical improvements, including ion transport membrane systems, the present inventors have actually integrated ion transport membrane systems based on the generation and synthesis of hydrogen separation systems using solid electrolyte ion transport membranes, and further in a single unit. Nothing about their separation was found.

It is an object of the present invention to provide a method for integrating hydrogen separation and synthesis gas production based on oxygen ion transport using a hydrogen transport membrane such as a hydrogen transport membrane based on palladium or a palladium alloy and a positive transport membrane.

It is a further object of the present invention to provide a method in which partial oxidation and steam reforming reactions occur together to achieve near energy neutral formation.

It is another object of the present invention to provide an improved process for producing syngas that is economical, flexible and thermodynamically efficient.

It is a further object of the present invention to harmonize the heat of reaction using a relatively large amount of oxygen-containing gas (generally air) on the cathode side of the oxygen ion transport membrane as the heat release agent.

A further object of the present invention is to allow the reactant gas at the anode side to flow countercurrently to an oxygen-containing stream (generally air) at the cathode side to lower the gas inlet and outlet temperatures below the reaction temperature.

It is a further object of the present invention to increase the conversion of organic fuel to synthesis gas at the anode side by removing hydrogen from the synthesis gas conversion zone using an ion transport membrane.

Other objects, features and advantages will become apparent to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings.

1 is a schematic diagram of a system for producing hydrogen gas and syngas according to the present invention wherein syngas is discharged from an oxygen ion transport membrane in an oxygen reactor and hydrogen gas is discharged from a hydrogen transport membrane in a hydrogen separator;

2 is a schematic diagram of a system for generating hydrogen gas and synthesis gas in accordance with the present invention in which oxygen is permeated through an oxygen ion transport membrane that produces a synthesis gas and hydrogen from the synthesis gas is permeated through a hydrogen transport membrane that produces hydrogen. The two membranes are located in one reactor.

The present invention relates to a method for producing hydrogen gas and synthesis gas. The method includes passing a compressed and heated oxygen containing gas mixture to an oxygen reactor having one or more solid electrolyte oxygen ion transport membranes. The reactor has a first zone and a second zone separated by an oxygen ion transport membrane. At least a portion of the oxygen from the mixture is transported through the oxygen ion transport membrane from the first zone to the second zone, reacting with the purification stream containing the gaseous organic fuel to generate an oxygen depleted retention stream from the first zone. The purification stream passes to the second zone and reacts with the transported oxygen to produce synthesis gas. The syngas is contacted with one or more hydrogen transport membranes to produce high purity hydrogen permeate and hydrogen depleted syngas retention. As a result, high purity hydrogen permeate is recovered as the hydrogen gas stream product.

Another embodiment includes passing a compressed and heated oxygen containing gas mixture to an oxygen reactor having one or more solid electrolyte oxygen ion transport membranes. The reactor has a first zone and a second zone separated by a first oxygen ion transport membrane. At least a portion of the oxygen from the mixture is transported through the oxygen ion transport membrane from the first zone to the second zone, producing an oxygen depleted retention stream from the first zone. The gaseous organic fuel, steam and optionally CO ₂ , pass to the second zone and react with the transported oxygen to produce syngas. The amount of steam and CO ₂ injected into the second zone can be adjusted to vary the ratio of H ₂ / CO in the resulting synthesis gas stream. A stream of syngas from the second zone is recovered and passed through a third zone in a hydrogen separator having one or more solid electrolyte hydrogen transport membranes. The hydrogen separator has a third zone and a fourth zone separated by a hydrogen transport membrane. At least a portion of the hydrogen gas is transported through the hydrogen transport membrane between the third and fourth zones to produce hydrogen permeate in the fourth zone and hydrogen depleted synthesis gas in the third zone. Hydrogen permeate as hydrogen product is recovered in the fourth zone. Hydrogen separation is chosen to operate at the same or moderately lower temperature as the oxygen ion transport membrane.

In another embodiment, the compressed and heated oxygen containing gas mixture is passed to an oxygen reactor having at least one solid electrolyte oxygen ion transport selection 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 from the mixture is transported through the oxygen ion transport membrane from the first zone to the second zone, feeding the first oxygen permeate stream and reacting with the purification stream containing the gaseous organic fuel, while retaining the oxygen depleted stream. Creates. The purification stream passes to the second zone and reacts with the transported oxygen to produce synthesis gas. The synthesis gas is directed to contact with one or more hydrogen transport membranes, producing a high purity hydrogen permeate in the third zone, with hydrogen depleted synthesis gas retentate remaining. The hydrogen permeate is then recovered in the third zone as the hydrogen product. One of the advantages of hydrogen recovery from the synthesis gas conversion zone is to maintain a suitable balance to complete the reaction.

In some embodiments, the oxygen containing gas mixture is at least partially by an indirect heat exchanger having one or more streams comprising oxygen depleted retention gas from the first zone, hydrogen depleted retention synthesis gas from the hydrogen separator and hydrogen permeate gas. Heated to.

The term reactor, as used herein, refers to a separator where oxygen is consumed as the transported oxygen undergoes a chemical reaction.

The present invention provides a process for hydrogen production using a solid oxygen ion transport membrane to separate oxygen from an oxygen containing gas, ie air, and to utilize oxygen separated from a partial oxidation reactant and optionally from a steam reforming reactant of a carbonaceous source. Can be achieved. Partial oxidation and / or steam reforming reactants produce syngas that is used to produce hydrogen in the case of hydrogen transport membranes.

Oxidation of the fuel at the anode side of the oxygen ion membrane reactor reduces the partial pressure of oxygen at the anode side of the membrane. This enhances the driving force in the oxygen reactor by achieving high oxygen flow rates and lower membrane area requirements. With the oxygen-containing feed gas at a relatively low pressure, the fuel side is maintained at a high pressure, which benefits even when the system requires lower power. The partial oxidation reaction, ie the exothermic reaction and the steam reforming reaction, ie the endothermic reaction, can be carried out in the same reactor, so as to obtain a nearly anneal neutral system. In addition, in the form of relatively large amounts of oxygen-containing gas (generally air), the heat sink allows further balance of the heat of reaction and adjusts the temperature of the reaction zone. In another embodiment, the partial oxidation and steam reforming reactions occur in an ion transport separator. The product synthesis gas produced by the oxygen ion transport reactor by partial oxidation and / or steam reforming reaction is then fed to a hydrogen membrane transport separator. Preferably, the oxygen containing gas and the reactant fuel flow in countercurrent. Relying on the introduction of fuel and oxygen containing gas streams at lower temperatures and internal heat transfer to the reactor, the critical reactor portion as a seal and structural component at the gas inlet and outlet of the reactor is reduced to mechanical design and lower manufacturing costs. It is possible to maintain at an intermediate temperature for ease.

Oxygen ion transport membranes are used to separate oxygen from an oxygen containing gas stream. Materials capable of conducting oxygen ions and electrons are referred to herein as mixed conducting oxides or mixed conductors. In the present invention, many potential mixed conductors have been identified in both fluorite and ash titanite crystal structures. Table I is a partial list of important mixed conductors for oxygen production.

Mixed conductor Substance composition One. (La _1-x Sr _x ) (Co _1-y Fe _y ) O _3-δ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, obtained from δ stoichiometry) 2. SrMnO _3-δ SrMn _1-x Co _x O _3-δ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, obtained from δ stoichiometry) Sr _1-x Na _x MnO _3-δ 3. _{BaFe 0.5 Co 0.5 YO 3 SrCeO 3} YBa 2 Cu 3 O 7-β ( obtained from 0≤β≤1, β stoichiometry) 4. La _0.2 Ba _0.8 Co _0.8 Fe _0.2 O _2.6 ; Pr _0.2 Ba _0.8 Co _0.8 Fe _0.2 O _2.6 5. A _x A '_x' A _x B _y B '_y' B _y O _3-z (x, x ', x, y, y', y all range from 0 to 1) where A, A ', A = Group 1,2,3- and f-block lanthanide series elements B, B ', B = d-block transition metals 6. (a) Co-La-Bi type: cobalt oxide 15-17 mol% lanthanum oxide 13-45 mol% bismuth oxide 17-50 mol% (b) Co-Sr-Ce type: cobalt oxide 15-40 mol% strontium oxide 40-55 mol% cerium oxide 15-40 mol% (c) Co-Sr-Bi type: cobalt oxide 10-40 mol% strontium oxide 5-50 mol% bismuth oxide 35-70 mol% (d) Co-La- Ce type: 10-40 mol% cobalt oxide 10-40 mol% lanthanum oxide 30-70 mol% (e) Co-La-Sr-Bi type: cobalt oxide 15-70 mol% lanthanum oxide 1-40 mol% Strontium oxide 1-40 mol% Bismuth oxide 25-50 mol% (f) Co-La-Sr-Ce type: cobalt oxide 10-40 mol% lanthanum oxide 1-35 mol% strontium oxide 1-35 mol% cerium oxide 30 -70 mol%

7. Bi _2-xy M ′ _x M _y O _3-δ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, obtained from δ stoichiometry) where: M ′ = Er, Y, Tm, Yb, Tb, Lu, Nd, Sm, Dy, Sr, Hf, Th, Ta, Nb, Pb, Sn, In, Ca, Sr, La and mixtures thereof M = Mn, Fe, Co, Ni, Cu and mixtures thereof 8. BaCe _1-x Gd _x O _{3-x / 2} ; where x is from 0 to about 1. 9. A _s A ' _t B _u B' _v B _w O _x A material of which the composition is described in U.S. Patent No. 5,306,411 to Mazanec et al .: A is a lanthanide or Y Or a mixture thereof; A ′ represents an alkaline earth metal or mixture thereof; B represents Fe; B ′ represents Cr or Ti, or a mixture thereof; B represents Mn, Co, V, Ni or Cu, or a mixture thereof; s, t, u, v, w and x have a s / t of about 0.01 to about 100; u of 0.01 to about 1; v of 0 to about 1; w of 0 to about 1; x is a number satisfying the valences of A, A ', B, B', and B in the formula; And 0.9 (s + t) / (u + v + w) to be 1.1. 10. La _1-x Sr _x Cu _1-y M _y O A material of group _3-δ , wherein: M represents Fe or Co; x is from 0 to about 1; y is from 0 to about 1; It is a number satisfying the valences of La, Sr, Cu and M in the formula. 11. One of the Ce _1-x A _x O _2-δ groups, wherein: A represents a lanthanide element, Ru or Y, or a mixture thereof; x is from 0 to about 1; y is from 0 to about 1 δ is a number satisfying the valences of Ce and A in the formula. 12. One of the Sr _1-x Bi _x FeO _3-δ groups, wherein: A represents a lanthanide element or Y, or mixtures thereof; x is from 0 to about 1; y is from 0 to about 1; δ Is a number satisfying the valences of Ce and A in the formula.

13. Sr _x Fe _y Co _Z O _{w A} group of substances, wherein: x is from 0 to about 1; y is from 0 to about 1; z is from 0 to about 1; w is of the formula Sr, Fe and Co The number satisfying the valence. 14. Double phase mixed conductor (electron / ionic): (Pd) _0.5 / (YSZ) _0.5 (Pt) _0.5 / (YSZ) _0.5 (B-MgLaCrO _x ) _0.5 (YSZ) _0.5 (In _90% Pt _10% ) _0.6 / (YSZ) _0.5 (In _90% Pt _10% ) _0.5 / (YSZ) _0.5 (In _95% Pr _2.5% Zr _2.5% ) _0.5 / (YSZ) _0.5 Hot metal phase on any of the materials described in 1 to 13 (For example, Pd, Pt, Ag, Au, Ti, Ta, W) is added.

Although mixed conductors or double phase conductors are preferred for pressure induced ion transport separators, the present invention also contemplates the use of electronically induced ion transport membranes. Typically, the ion transport membrane can be in the form of a dense or thin film supported on the porous material. The thickness of the membrane layer is typically less than about 5000 microns, preferably less than 1000 microns, and most preferably less than 100 microns. The ion transport membrane can be tubular or planar.

Similarly, hydrogen transport membranes are used to separate hydrogen from syngas streams. Many hydrogen separation units such as palladium or palladium alloys, or positive conductors using any of several high temperature hydrogen technologies, for example hydrogen permeable solid membranes are available. Preferably, a positive conductor is used. Table II is a partial list of important hydrogen conductors for hydrogen separation.

High temperature proton conductors (footnote: where 'd' means oxygen bond per unit) Substance composition One. Doped silt based on: (a) SrCe _1-x M _x O _3-δ (e.g., Sr _0.95 Ce _0.05 YbO _3-δ ) and (b) BaCe _1-x M _x O _3-δ (e.g., BaCe _0.8 Y _0.2 O _3-δ and BaCe _0.9 Nd _0.1 O _3-δ ) where x <generally higher than about the upper limit of the solid solution formation range, typically about 0.2 (dough The printed barium lead has the highest conductivity.) 2. Solid solution heat substituted as follows: (a) SrCe _0.9 Y _x Nb _y O _3-δ [δ = (xy) / 2 and x + y = 0.1] and (b) SrCe _1-z Zr _z Y _0.05 O _3-δ [δ = 0.025] 3. Receptor (Sc, Y, Yb) -doped SrZrO ₃ and SrTiO ₃ , gray titaniumite 4. Dough based on CaZrO ₃ (eg CaZr _0.9 In _0.1 O _3-δ ), SrZrO ₃ (eg SrZr _0.95 Y _0.05 O _3-δ and SrZr _0.9 Yb _0.1 O _3-δ ) and BaZrO ₃ Printed Zirconate 5. SrYb _0.05 (Ce _1-x Zr _x ) _0.95 O _3-δ [eg, obtained from x = 0, 0.25, 0.5, 0.75, 1.0 and δ stoichiometry] 6. A ₂ (B'B) O ₆ [B 'and B ions are 3+ and 5+], A ₃ (B'B ₂ ) O ₉ [B' and B ions are 2+ and 5+, while A Ions are always 2+] complex gray titaniumite, for example Ba ₃ (CaNB ₂ ) O ₉ 7. Receptor (M = Gd, Y) -doped BaCeO ₃ ie (Ba _1-x M _x ) (Ce _1-y M _y ) O _3-δ 8. BaCe _1-x Ca _x O _3-δ 9. Pyrochlor-type structure oxide ceramic A ₂ Zr _2-x Y _x O _7-δ (A = La, Nd, Gd, Sm) Y ₂ Ti _2-x M _x O _7-δ (M = In, Mg) 10. Hydrogenated yttrium-barium cuprate H _x Ba ₂ YCu ₃ O _{y '} , wherein x = 2m + h, y = 6.5 + m + d; m = 0,1,2; h>0; d <1 11. KTaO ₃ -based oxides and Y ₂ O ₃ ceramics

The method of the present invention can be illustrated by the schematic diagram of the system 50 of FIG. 1, and a process method for using ion transport techniques for syngas and hydrogen gas generation is provided. The oxygen containing gas stream 1 (preferably air) is compressed to low pressure using a blower and then heated against the oxygen depleted retention stream 8 in the heat exchanger 3 and then optionally heated. And is passed to the oxygen reactor 6 via the heater 4 to discharge it as a compressed oxygen containing gas stream 5. In one embodiment, stream 8 is discharged as waste and in another embodiment it is used as a nitrogen generating stream. The gas stream 5 is fed to a first zone of the oxygen ion transport membrane reactor 6, which is divided into a first zone 40 and a second zone 41 by an oxygen ion transport membrane 7. have. As used herein, the first zone 40 is where the oxygen containing gas 5 is supplied, referred to as the cathode or the holding side. Typically, the pressure in the first zone 40 is 1 to 40 atm, preferably 1 to 10 atm. In the reactor 6, the oxygen of the oxygen kadb gas stream 5 in the first zone 40 is removed and the outlet stream 8 is an oxygen depleted stream. Oxygen ion conductivity of the membrane is typically 0.01 to 100 S / cm, where S is 1 / ohm. Oxygen is transported through the membrane 7 to a second zone 41, referred to as permeate or anode group, which is reactively purified using a gas mixture 9 containing organic fuel 10. It became. If liquid carbonaceous fuels are used to produce hydrogen, they must be evaporated before entering the reactor or evaporating. The pressure in the second zone 42 is usually 1 to 100 atm, preferably 1 to 40 atm. In one embodiment the organic fuel is a carbonaceous fuel, preferably methane or clean combustion natural gas, which are optionally pressurized by the compressor 11, preferably further heated by the heater 12, and steam Or atomized water 13 and recycle permeate stream 14 from hydrogen transport membrane separator 16.

While hydrogen permeable membranes have been used in the present invention to effect hydrogen separation, other separators known to those skilled in the art, such as pressure swing adsorption, temperature swing adsorption, low temperature gas separators, polymeric membranes for gas separation, may also be applied. .

Steam or atomized water added to the fuel stream promotes steam reforming action and increases the hydrogen concentration in the synthesis gas 15. This is because steam reforming generally produces much higher amounts of hydrogen than partial oxidation processes. For example, if methane is used as fuel, steam reforming provides 50% more than hydrogen in a partial oxidation process.

While the partial oxidation of hydrogen fuel is an exothermic reaction, the steam reforming action is generally an endothermic reaction. Depending on the heat requirements and heat transfer properties of the system, one or both of partial oxidation and steam reforming reactions can be carried out using suitable catalysts. As a result, the use of both partial oxidation and steam reforming action facilitates the achievement of an energy neutral ion transport system, where the exothermic nature of the partial oxidation action provides energy effectively for the steam reforming action. This also promotes the achievement of self-sustaining action of heat. As discussed earlier, the reaction temperature is further suppressed by the heat sink in the form of a relatively large amount of oxygen containing gas (generally air).

At typical temperatures of ion transport membrane action, the partial pressure of oxygen in the oxygen consuming gas stream is low. Since oxygen transport is induced by the difference in oxygen activity on the opposite side of the membrane, even when the pressure of the oxygen containing gas is relatively low, the low partial pressure quickly promotes oxygen transport through the oxygen ion transport membrane. This side of the reactor allows oxygen to be transported with low power requirements.

The partial pressure of oxygen can be increased to enhance oxygen flow through the oxygen transport membrane. For example, if air is used as the oxygen containing feed gas and nitrogen is required and pressurized at high pressure, air may be beneficial. Similarly, if nitrogen is not needed as the product at increased pressure, but compressed, air may be undesirable. Retention streams may be expanded to overcome some of the effects of compression or may be combusted in gas turbines to generate power. If power generation is desired, the oxygen containing gas (typically air) should be pressurized to a typical gas turbine inlet pressure (100-250 psi). In addition, if nitrogen is not needed as the product, it may be advantageous to compress the oxygen containing gas (generally air) to the pressure necessary only to offset the change in pressure loss in the reactor.

Under ordinary operating conditions of an oxygen ion transport membrane reactor, the fuel gas undergoes a partial oxidation reaction to produce a variety of other components including synthesis gas (hydrogen and carbon monoxide), carbon dioxide, water, and other small components such as higher hydrocarbons. . The catalyst can be used in the second zone of the reactor to enhance the desired partial oxidation and steam reforming reactions.

External catalysts to promote partial oxidation / steam reforming reactions can be disposed in a number of ways, including depositing on transport membranes, fixed beds, fluidized beds, catalyst rods, or tubes. For example, the partial oxidation catalyst may be disposed on the surface of the oxygen ion transport membrane and the steam reforming catalyst may be disposed in the form of a fixed bed. Partial oxidation and steam reforming reactions may require different catalysts, and the extent of the reaction may be adjusted by mixing the respective catalysts in appropriate proportions as assessed by those skilled in the art. For example, stacking of partial oxidation and steam reforming catalysts (eg, Nio based catalysts) can be used to adjust the carbon monoxide / hydrogen ratio in the synthesis gas. The concentrations of steam and CO _{2 in} the purified gas phase can be used to adjust the carbon monoxide / hydrogen ratio in the synthesis gas.

In FIG. 1, syngas 15 is withdrawn from oxygen reactor 6 via a partial oxidation reaction of fuel in second zone 41 of reactor 6. Optionally, syngas 15 may be removed or recovered. The stream of syngas 15 can then be fed to a second downstream hydrogen membrane separator. If the operating temperature of the hydrogen transport membrane is lower than the operating temperature of the oxygen ion conducting 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 also separates into a third zone 42, also referred to as the hydrogen retention side or cathode side, and a fourth zone 43, referred to as the hydrogen permeation side or anode side. do. The third zone 42 and the fourth zone 43 are separated by one or more hydrogen transport membranes 30.

Hydrogen gas is permeated through one or more hydrogen transport membranes 30 of the hydrogen separator 16. The product hydrogen gas stream 17 exiting the fourth zone 43 in the separator 16 may enter the heat exchanger 3 and transfer heat to the upstream oxygen containing gas stream 1.

It is important that the high pressure of the synthesis gas be maintained to support the different hydrogen partial pressures required, with the hydrogen transport membrane in between. In this embodiment, the compressor 11 compresses the fuel gas to provide the desired conditions for the reaction in the second zone 41 and the required hydrogen partial pressure in the second zone 41 for effective oxygen transport downstream. can do. Preferably, a pressure of about 10 to 50 atm is provided.

Preferably, the carbon monoxide rich stream 18 exiting the third zone is used to heat the oxygen containing gas stream 1 in the heat exchanger 3. Further recovery of hydrogen from the retention stream 18 can be achieved in another recoverer 19 through which the carbon monoxide rich stream 21 passes. In this way, the separator provides a hydrogen stream 20 for addition to the hydrogen gas stream 17.

This downstream hydrogen recovery process in separator 19 is based on low temperature or palladium or palladium alloys under conventional methods known in the art, such as, for example, pressure switch adsorption, thermal swing adsorption, polymeric membranes. It may be carried out under increased temperature using a solid hydrogen transport membrane such as a hydrogen transport membrane or an electrolyte or a pressure induced positive conductor membrane. It should be noted that if a positive conducting membrane is used for hydrogen separation, the electrode and external circuitry are needed for the electrically induced action. If the hydrogen transport membrane has sufficient electron conductivity, pressure induced hydrogen separation can be performed in situ. The choice of downstream hydrogen separation action depends on the pressure and purity required for hydrogen and carbon monoxide gas. For example, methods using polymeric membranes will provide a slightly impurity hydrogen stream (90-96%) at low pressures and relatively pure carbon monoxide at high pressures, whereas pressure swings of hot syngas mixtures Adsorptive separation will provide a purer hydrogen stream (96 to 99.9%) at high pressures and impurity mixed carbon monoxide at low pressures. Palladium-based hydrogen transport membranes or positive conduction membranes allow the production of very high purity H ₂ streams due to their infinite selectivity for hydrogen transport.

The hydrogen concentration in the carbon monoxide-rich stream can be adjusted using many operating parameters, for example, by varying the hydrogen partial pressure across the hydrogen transport membrane. Similarly, various parameters associated with the hydrogen transport membrane can be adjusted, for example, by varying the thickness and area of the membrane.

Carbon monoxide from the carbon monoxide rich stream 21 may be recovered from the reactor 22 which produces the enriched carbon monoxide stream 23. The remaining waste carbon monoxide stream 14 is optionally disposed of as waste stream 24 or mixed with the stream organic fuel stream 10 and recycled to the oxygen ion transport reactor 6.

If carbon monoxide is not desired as a product, it can be used as fuel to provide heat input at various stages of the process. For example, a waste heat boiler can be used to generate the steam needed for the process.

In addition, if carbon monoxide is not desired as a product, it can be converted to carbon dioxide as well as increasing hydrogen yield by carrying out a water-gas shift reaction. Optionally, carbon monoxide can also be burned to provide the heat needed at various points in the system. Carbon monoxide can also be combusted in a casing turbine integrated with the present system for generating power.

Another embodiment of the present invention is the system 250 shown in FIG. In this embodiment, the oxygen ion transport membrane reactor is combined with the hydrogen separator in a single unit. The system is capable of oxygen separation, syngas production and hydrogen separation in the same membrane providing improved homogeneous conditions in the reactor.

Oxygen containing gas stream (preferably air) 201 is compressed at high pressure using blower 202 and then heated waste (or nitrogen product) stream 208 in heat exchanger 203 and heated The compressed oxygen containing gas stream 205 is sent to an optional heater 204 which exits. A gas stream 205 is supplied to the first zone 204 of the oxygen ion transport membrane reactor 206, which is connected to the first zone 240 and the second zone 241 by the oxygen ion transport membrane 207. Separated by. As used herein, the first zone is where the oxygen containing gas 205 is supplied, optionally referred to as an oxygen cathode or an oxygen retaining side. In the reactor 206, a portion of the oxygen containing gas in the first zone 240 is removed and the outlet stream 208 is a nitrogen rich stream. Oxygen is transported through the membrane 207 to the second zone 241, which is optionally upgraded to the permeate side or to the anode side, where it is purified using a gas mixture 209 containing organic fuel 210. do.

Under ordinary operating conditions in ion transport membrane reactors, the fuel gas produces partial oxidation to produce synthesis gas and various other components including carbon dioxide, water and other hydrocarbons. The catalyst may be mixed into the second zone 241 of the reactor 206.

Purification gas 209 is a carbonaceous fuel, preferably methane or natural gas. Purified gas 209 is preferably compressed in compressor 211, and may optionally be further heated in heater 212, mixed with steam or atomized water 213, and depleted syngas stream 214. Recycle).

At typical temperatures of ion transport membrane operation, the oxygen partial pressure in the purge gas stream is low, typically less than 10 ^-10 atm, which facilitates rapid oxygen transport through the oxygen ion transport membrane and permits low pressure in the oxygen containing gas stream. to be. This aspect of the reactor allows oxygen to be transported even with low power requirements.

Reactor 206 also features a hydrogen transport membrane 225 in which hydrogen transport through the membrane 225 takes place as a discharge of high purity hydrogen permeate to the third zone 242, the third zone. May optionally be referred to as hydrogen permeation or anode side. Removal of hydrogen changes the uniform conditions of the second zone 241 which are suitable for increasing the yield of hydrogen.

Emission from reactor 206 via partial oxidation of fuel 210 in second zone 241 is carbon monoxide rich stream 218, which may be removed and recovered. Stream 218 may be used to provide heat for the oxygen containing gas stream 201 in heat exchanger 203. The hydrogen recovery also exhausts the carbon monoxide rich stream 221 and provides a stream 218 where the hydrogen stream 220 passes through the separated separator 219. Recovery of the carbon monoxide stream 221 as pure or nearly pure carbon monoxide 223 occurs in the carbon monoxide separation unit 222. The depleted waste stream 214 exits the carbon monoxide separation unit 222 and optionally exits as waste stream 224.

Hydrogen rich stream 217 exiting third zone 242 of reactor 206 passes through heat exchanger 203. Individually, hydrogen rich stream 220 separated from carbon dioxide rich stream 218 in separator 219 combines with hydrogen rich stream 217 to form hydrogen rich stream 229.

The system provided by the embodiment of FIG. 2 also encourages more product of the synthesis gas. Since hydrogen is separated in situ, the partial pressure of hydrogen is reduced in the partial oxygen reaction. As a result, the LeChatlier principle supports square syngas formation by further changing the partial oxidation / steam reforming reaction towards the product. By injection of the organic fuel into the second zone under increased pressure, hydrogen is produced under sufficiently high pressure to drive them through the hydrogen transport membrane. Alternatively, the pure gas may be used for effective hydrogen separation in embodiments using independent oxygen and hydrogen separators. For example, steam can be used as a pure gas in a hydrogen separator because steam can be easily separated from hydrogen by condensation.

If the conversion in the reactor is incomplete, the purified stream will contain untreated fuel and at least a portion of the stream may be recycled to the reactor, preferably after hydrogen and carbon monoxide have been removed.

Various other aspects of the embodiment of FIG. 1 as described above may also be applied to the embodiment of FIG. 2 and will be appreciated by those skilled in the art. Various actions, such as heat exchange in heat exchanger 3 or 203, have been described in US Patent Application No. It may be incorporated into the reactor 6 or 206 as described in the foregoing, which is incorporated herein by reference.

It is anticipated that the present invention may be extended with products further derived from the present invention. For example, the separated hydrogen rich and cant rich streams generated from the present invention can also be used to produce ammonia. In addition, syngas as produced by the present invention can be used as a fuel element and is a valuable commercial product for the production of chemicals such as methanol, acetic acid, dimethyl ether, acetonitrile and formaldehyde. Thus, the synthesis gas production process can be integrated with downstream action, optionally with adjustment of the hydrogen / carbon monoxide ratio.

Specific features of the invention are shown in one or more figures for convenience only, each of which is associated with another feature according to the invention. Alternative embodiments will be recognized by those skilled in the art and are included within the claims of the present invention.

As described above, according to the present invention, hydrogen separation or hydrogen separation based on oxygen ion transport was integrated using a hydrogen transport membrane or a positive transport membrane such as a hydrogen transport membrane based on palladium or a palladium alloy. Thus, the above-mentioned problems of the prior art have been solved.

Claims (10)

(a) passing the compressed and heated oxygen containing gas mixture into an oxygen reactor comprising at least one solid electrolyte oxygen ion transport membrane, the reactor having a first zone and a second zone separated by an oxygen ion transport membrane, At least a portion of the oxygen from the mixture is transported from the first zone to the second zone through an oxygen ion transport membrane, generating a first permeate stream from the second zone and reacting with the purification stream containing the gaseous organic fuel. Producing an oxygen depleted retention stream from zone 1; (b) passing the refinery stream to a second zone to produce syngas in the first permeate stream by reacting with the transported oxygen; (c) moving the first permeate stream to contact one or more hydrogen transport membranes to produce high purity hydrogen permeate and hydrogen depleted syngas retentate; (d) recovering the high purity hydrogen permeate as a hydrogen gas stream product. The method of claim 1 further comprising a hydrogen separator having a hydrogen transport membrane and a conduit leading the first permeate stream to the hydrogen separator. The method of claim 1, wherein the oxygen containing gas mixture is at least partially heated by heat exchange with at least one oxygen depleted retention gas from the first zone, a hydrogen depleted syngas retentate from a hydrogen separator, and a hydrogen permeate gas. How to. The method of claim 1, wherein the gaseous organic fuel consists of an organic fuel treated with steam or atomized water. (a) passing the compressed heated oxygen-containing gas mixture through an oxygen reactor comprising at least one solid electrolyte oxygen ion transport membrane, the reactor passing through a first zone and a second zone separated by a first oxygen ion transport membrane. At least a portion of the oxygen from the mixture from the first zone to the second zone via an oxygen ion transport membrane to supply a first oxygen permeate stream and react with a purification stream containing a gaseous organic fuel, Generating an oxygen depleted retention stream from the zone; (b) passing the refinery stream to a second zone to produce syngas by reacting with the transported oxygen; (c) withdrawing and passing a first permeate stream of syngas from a second zone to a third zone in a hydrogen separator comprising one or more solid electrolyte hydrogen transport membranes, the hydrogen separator being separated from each other by a hydrogen transport membrane; Having three zones and a fourth zone, at least a portion of the synthesis gas is transported from the third zone to the fourth zone through the hydrogen membrane, generating hydrogen permeate in the fourth zone and generating hydrogen depleted synthesis gas in the third zone. Making a step; And (d) recovering hydrogen permeate from the fourth zone as a hydrogen gas stream product, thereby producing hydrogen gas. 6. The process of claim 5, wherein the temperature of the stream of syngas is optionally lowered before passing through the hydrogen separator. The process of claim 5, wherein the mixture is at least partially by indirect heat exchange with at least one oxygen depleted retentate from the first zone, hydrogen depleted retention synthesis gas from the third zone, and hydrogen permeate from the fourth zone. Heated. (a) passing the compressed and heated oxygen containing gas mixture through a membrane reactor comprising at least one solid electrolyte oxygen ion transport selection membrane and at least one solid electrolyte hydrogen ion transport membrane, the reactor comprising a first zone, a second zone and Having a third zone and transporting at least a portion of the oxygen from the mixture from the first zone to the second zone through an oxygen ion transport membrane to generate an oxygen depleted retention stream from the first zone; (b) passing the gaseous organic fuel into the second zone to react with the transported oxygen to produce a synthesis gas; (c) moving the synthesis gas into contact with the one or more hydrogen transport membranes to generate high purity hydrogen permeate in a third zone and generate a hydrogen depleted syngas retentate in a second zone; And (d) recovering hydrogen permeate from the third zone as a hydrogen gas stream product, thereby producing hydrogen gas. The method of claim 8, wherein the mixture is at least partially heated by indirect heat exchange with one or more oxygen reserves from the first zone, hydrogen depleted syngas from the second zone, and hydrogen permeate from the third zone. How to feature. 9. The method of claim 8, wherein the gaseous organic fuel consists of organic fuel treated with steam or atomized water.