MXPA99005119A - Membrane reformer ceram - Google Patents

Abstract

A process for generating an improved production of a desired product to be stopped from an ion transport reactor using the reaction products of both the cathode side and the anode side of an oxygen selective ion transport ceramic membrane is described. A first oxygen donor feed stream containing the desired product in a chemically bound state is supplied to the cathode side, while a second oxygen acceptance feed stream is supplied to the anode side. After chemical reactions on both the cathode side and the anode side, a desired product is recovered from the first product stream leaving the cathode side and from a second product stream leaving the side of the anode, so that the sum of the desired product contained within the two streams of product exceeds that which can be obtained from any product stream.

Description

CERAMIC MEMBRANE REFORMER FIELD OF THE INVENTION This invention relates to a process for improving the recovery of desired products from an ion transport reactor. More particularly, the desired products are recovered from both the anode side and the cathode side of the reactor thus increasing the production of desired products.

BACKGROUND OF THE INVENTION Petroleum and petrochemical companies have discovered vast amounts of natural gas in far-flung places such as polar and submarine regions. Transportation of natural gas, which consists mostly of methane, is difficult, and methane can not currently be economically converted to more valuable products, such as hydrogen, or to products that are more economically contained or transported, such as liquid fuels. including methanol, formaldehyde and olefins. Typically, methane is converted to synthesis gas, an intermediate in the conversion of methane to liquid fuels. The synthesis gas is a mixture of hydrogen and carbon monoxide with a molar ratio of H2 / CO of about 0.6 to about 6.

The conversion of methane to synthesis gas is currently achieved through either a methane vapor reforming process or a carbon dioxide reforming process. The methane vapor reformation is an endothermic reaction: (1) CH4 + H2O = _ > CO + 3H2. This process has a relatively high production of hydrogen gas (H2), producing 3 moles of hydrogen gas for each mole of carbon monoxide produced. The reaction kinetics requires the addition of significant amounts of heat that make the process economically less desirable. The carbon dioxide reformation is also an endothermic process: (2) CH4 + HzO = > 2CO + 2H2. The carbon dioxide reforming reaction is a little less efficient than the methane vapor reforming reaction, generating one mole of hydrogen gas per mole of carbon monoxide formed. The endothermic reaction requires the entry of a significant amount of heat, making the process also economically less desirable. Another aspect is the direct partial oxidation of methane, which may use an ion conducting membrane reactor or a composite conducting membrane reactor according to the equation: (3) CH4 + 1 202 = > CO + 2H2. In an ionic or composite conducting membrane reactor, a solid electrolyte membrane having oxygen selectivity is disposed between an oxygen-containing feed stream and an oxygen consumption product stream, typically containing methane. "Oxygen selectivity" means that oxygen ions are transported through the membrane while other elements, and ions thereof, are not. The solid electrolyte membrane is made from inorganic oxides, typified by zirconium stabilized with calcium or yttrium and analogous oxides, usually having a structure of fluorite or perovskite. At elevated temperatures, typically in excess of 500 ° C, and preferably in the range of 700 ° C-1200 ° C, the solid electrolyte membranes contain voids of mobile oxygen ion that provide conduction sites for the selective transport of ions of oxygen through the material. Since the membranes only allow the transport of oxygen, they function as a membrane with an infinite selectivity for oxygen and are, therefore, very attractive for use in air separation processes. In an ion-type system, the membrane carries only oxygen ions and the two electrons released by oxygen in the course of equation (3) are transported through the membrane through an external electric field. The patent of E.U.A. No. 4,793,904 to Mazanec et al., which is incorporated herein by reference in its entirety, describes an ion transport membrane coated on both sides with an electrically conductive layer. A gas containing oxygen makes contact with one side of the membrane. The oxygen ions are transported through the membrane to the other side where the ions react with methane or similar hydrocarbons to form syngas. The electrons released by the oxygen ions flow from the conductive layer to the external cables and can be used to generate electricity. In a composite conductor type membrane, the membrane is a double-phase ceramic having the ability to selectively transport both oxygen ions and electrons. With this type of membrane, it is not necessary to provide an external electric field to remove the electrons released by the oxygen ions. The patent of E.U.A. No. 5,306,411 to Mazanec et al., which is incorporated herein by reference in its entirety, describes the application of a composite conductive type membrane. The membrane has two solid phases in a crystalline structure of perovskite: a phase for the transport of oxygen ion and a second phase for the conduction of electrons. The oxygen ion transport is described as being useful for forming synthesis gas and for remediating combustion gases such as NOx and SOx. The patent of E.U.A. No. 5,573,737 to Balachandran et al., also discloses the use of an ionic or composite conducting membrane to separate oxygen and subsequently react the oxygen ions with methane to form the synthesis gas. The partial oxidation reaction is exothermic and once started does not require additional heat input. However, the production of two moles of hydrogen gas per mole of carbon monoxide produced is 33% less than the production obtained through the reformation of conventional steam methane (see equation 1). The integration of an ion transport membrane with other devices or processes to improve either production or efficiency is described in the patent application of E.U.A. commonly assigned series number 08 / 848,200 entitled "Method of Producing Hydrogen Using Solid Electrolyte Membrane" by Gottzmann and others, filed on April 29, 1997, and incorporated herein by reference in its entirety. An oxygen-selective ion transport membrane and a proton-selective membrane (hydrogen ion) combine to improve the production of hydrogen gas. The oxygen ions transported through the selective oxygen membrane are reacted with hydrocarbons to form the synthesis gas. The synthesis gas makes contact with a proton-selective membrane that selectively transports hydrogen ions that will be reformed as hydrogen gas. The patent application of E.U.A. commonly assigned series number 08 / 848,258 entitled "Method for Producing Oxidized Product and Generating Power Using a Sohd Electrolyte Membrane Integrated with a Gas Turbine" by Drnevich and others, filed on April 29, 1997, and incorporated herein by reference in its entirety, describes the integration of a transport membrane with a gas turbine. A gas stream containing oxygen makes contact with an oxygen selective transport membrane. Oxygen ions transported through the membrane are used to generate oxidized products. The oxygen-depleted supply material stream, ie, heated during the isothermal reaction, is supplied to a gas turbine combustor at an elevated temperature. Direct partial oxidation is also possible using oxygen that has been separated out of the reactor, such as through distillation or pressure swing adsorption (PSA). A conventional catalytic chemical reactor can be used for the reaction and, in that case, no membrane is necessary. Direct partial oxidation can also be done using air, instead of oxygen, however the process becomes less economical. Although the integration improves the economic desire of the direct partial oxidation reaction, there remains the need to improve the production achieved by the process at levels roughly equivalent to the steam methane reforming process.

OBJECTS OF THE INVENTION Therefore, it is an object of the invention to provide a process for generating an improved output of a desired product from an ion transport reactor. It is a further object of this invention to provide a process that will improve the production of hydrogen gas from the direct partial oxidation of methane.

Another object of the invention is to simultaneously use the chemical reactions that occur on both sides of an ion transport membrane to obtain the improved production of the desired product. A further object of this invention is to provide said desired product, together with useful by-products. Such by-products may include, without limitation, carbon dioxide, carbon monoxide, nitrogen, argon, electrical energy, and combinations thereof.

COMPENDIUM OF THE INVENTION This invention comprises a process for generating an improved production of a desired product from an ion transport reactor. According to the process, an ion transport reactor having an oxygen selective ion transport membrane disposed within the reactor is provided. The oxygen selective ion transport membrane has a cathode side and an anode side. A first oxygen donor feed stream containing the desired product in a chemically bound state is supplied to the side of the cathode at a first partial pressure of oxygen. At the same time, a second oxygen acceptance feed stream containing a desired product, such as hydrogen, in a chemically bound state is supplied to the anode side and establishes a second partial pressure of oxygen on the anode side. The first oxygen pressure is selected to be greater than the second oxygen partial pressure. The selective oxygen ion transport membrane is operated at a high temperature which is sufficient to facilitate the transport of oxygen through the membrane. The elemental oxygen obtained from the first supply material is transported through the membrane to react with the second feed stream. A first product stream is then recovered from the cathode side of the ion transport reactor. This first product stream contains a first portion of the desired product. A second product stream is then recovered from the anode side and contains a second portion of the desired product. The sum of the first portion plus the second portion provides a total of the desired product. The conversion rate for the desired product of the combination of the first portion and the second portion preferably exceeds that which can be obtained from the second feed stream alone. thus providing the improved production of the desired product.

In a preferred embodiment, the first oxygen donor feed stream contains at least one component selected from the group consisting of NOx, water vapor, carbon dioxide and combinations thereof and the second oxygen acceptance feed stream contains at least one component selected from the group consisting of reagents containing hydrogen, reagents containing carbon, and combinations thereof. In another preferred embodiment, the reactor is operated at a temperature in an excess of 500 ° C. In another preferred embodiment, the hydrogen gas is separated from both the first portion and the second portion as the desired product.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, aspects and advantages will occur to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings, in which: Figure 1 illustrates a transverse representation of a conductor ion transport membrane compound operated as a reforming reactor according to the invention; Figure 2 is a process flow diagram illustrating the generation of hydrogen gas from the cathode side of the composite conductor ion reactor of Figure 1; Figure 3 is a process flow diagram illustrating a first method for isolating hydrogen gas and carbon dioxide from the anode side of the composite ion transport reactor of Figure 1; Figure 4 is a process flow diagram illustrating another process for isolating hydrogen gas and carbon dioxide from the anode side of the composite ion reactor of Figure 1; Figure 5 is a process flow diagram illustrating a first method for obtaining carbon monoxide from the anode side of the composite ion transport reactor of Figure 1; Figure 6 is a process flow diagram illustrating a process for obtaining both hydrogen and carbon dioxide from the anode side of the composite ion transport reactor of Figure 1; Figure 7 illustrates a process for obtaining carbon dioxide, hydrogen gas and carbon monoxide from the anode side of the composite transport reactor of Figure 1; Figure 8 illustrates a transverse side representation of a chemical reactor containing both an oxygen-selective compound ion transport membrane and a proton-selective compound ion transport membrane; Figure 9 illustrates the reactor of Figure 8 in a transverse end representation along lines 9-9 in Figure 8; Figure 10 is a process flow diagram illustrating a process of the invention for improving the production of hydrogen from methane; Figure 10A is a diagram illustrating a portion of an alternative arrangement for the process of Figure 10; and Figure 11 illustrates a cross-sectional representation of a thermoneutral composite ion transport reactor operated in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION This invention can be achieved by providing an ion transport reactor containing an oxygen selective ion transport membrane having a cathode side and an anode side and operating the reactor as a ceramic membrane reformer. By supplying an oxygen donor feed stream containing a desired product in a state chemically bound to the cathode side while simultaneously supplying an oxygen accepting feed stream containing hydrogen in a state chemically bound to the anode side, products can be isolated of the output currents on both the anode side and the cathode side. The total of the desired product obtained from these two separate outlet streams of said ceramic membrane reformer exceeds the total output that can be obtained from any single stream. Figure 1 illustrates a cross-sectional representation of a transport reactor of 10 to be operated as a ceramic membrane reformer in a process of the invention. Since the ion transport reactor 10 is of the composite conductor type, an ionic conducting membrane reactor can be used without significantly affecting the process of the invention. Membranes operating in a partial pressure gradient are preferred, since no external force is required to drive oxygen separation. However, an external current can be used to drive the ion transport through the dense membranes without affecting the spirit of the invention. Since the addition of an external current requires equipment and extra cost, the economics of the process may not be changed substantially. Arranged within the ion transport reactor 10 is an oxygen selective ion transport membrane 12. The oxygen selective ion transport membrane 12 has a cathode side 14 and an anode side 16. The ion transport membrane is Oxygen selective 12 is formed either as a dense-walled solid oxide double-phase or composite phase conductor, or alternatively as a thin-film solid oxide double or composite phase conductor that is supported on a porous substrate. The ion transport material has the ability to transport oxygen and electron ions to the oxygen partial pressure prevailing on the temperature scale from about 500 ° C to about 1200 ° C, when a chemical potential difference is maintained through the membrane surface of ion transport caused by a ratio in the partial pressures of oxygen through the ion transport membrane. Suitable materials for the ion transport membrane include double-phase metal-metal oxide-metal couplers and combinations as listed in Table 1. As the reactive environment on the anode side 16 of the selective ion transport membrane of oxygen 12, in many applications, creates very low partial oxygen pressures, the perovschites containing chromium in Table 1 may be the preferred material, since these tend to be stable in the low partial oxygen pressure environment. Chemically-containing perovskites do not decompose at very low partial oxygen pressures. Optionally, a layer of porous catalyst, possibly made from the same perovskite material, can be added to one or both sides of the oxygen transport membrane to improve oxygen surface exchange and chemical reactions on the surface. Alternatively, the surface layers of the oxygen selective ion transport membrane can be combined, for example, with cobalt, to improve the surface exchange kinetics.

TABLE 1 BaCei Oxygen Ion Conductor Materials xGd 3 3-x 2 where, x equal to zero to about 1 One of the materials of the ASA'.BUB vB '' wOx family whose composition is described in the US patent 5, 306, 441 (Mazanec et al) as follows A represents a lanthanide or Y, or a mixture thereof, A 'represents an alkaline earth metal or a mixture thereof, B represents Fe, B' represents Cr or Ti, or a mixture of the same, B "represents Mn, Co, V, Ni or Cu, or a mixture thereof, and s, t, u, v, w and x are numbers so that s / t equal to about 0 01 to about 100, or equal from about 0 01 to about 1, v equal to zero to about 1, w equal to zero to about 1, x equal to a number that satisfies the valences of A, A, B, B, B "in the formula, and 0 9 <; (s + t) / (u + v + w) < 1 1 One of the materials of the La? -? SrxCu family? yMy? 30, where M represents Fe or Co, x equal to zero to approximately 1, and equal to zero to approximately 1, d equal to a number that satisfies the valences of La, Sr, Cu, and M in formula One of the materials of the family Ce? -xAx? 2", where A represents a lanthanide, Ru or Y, or a mixture thereof, x is equal to zero to about 1, d equal to a number that satisfies the valences of Ce and A in the formula One of the materials of the Sn xBixFeOs-c family where x equals zero to about 1, d equals a number that satisfies the valences of Sr, Bi, and Fe in the formula One of the materials of the Sr family - FeyCozOw, where x equal to zero to approximately 1, and equal to zero to approximately 1, z equal to zero to approximately 1, w equal to a number that satisfies the valences of Sr, Fe, and Co in the formula Double phase composite conductors ( electronic / ionic) (Pd) 0 s / (YSZ) as (Pt) 0 5 / (YSZ) c _ .B-MgLaCrO c = (YSZ) 0 s (lnSo% Pt? o%) or 6 / (YSZ) or 5 (ln90% Pt, or%) or 5 / (YSZ) or 5 (ln95% Pr25% Zr25%) os / (YSZ) 05, Any of the materials described in 1-13, to which a phase is added high temperature metal (for example 0, Pd, Pt, Ag, Au, Ti, Ta, W) is added.

The ion transport reactor 10 is operated at an elevated temperature which is sufficient to facilitate the transport of oxygen ion through the oxygen selective ion transport membrane. The operating temperature is at least 500 ° C, and preferably in the range from 700 ° C to 1200 ° C, approximately, and most preferably in the scale of approximately 800 ° C around 1000 ° C. During operation, the first oxygen donor feed stream 18 is supplied to a first reaction vessel or chamber 20 in contact with the cathode side 14 of the oxygen selective ion transport membrane 12. The first donor feed stream of Oxygen 18 can be any gaseous composition containing the desired product in a chemically bound state. This includes compositions that are gaseous at the operating temperature of the transport reactor, even if it is in a different state at room temperature, eg, steam. Illustrative compositions for the first feed stream 18 include Nox (where x is 0.5 to 2) water vapor and combinations thereof. Simultaneous with the supply of the first oxygen donor feed stream 18 to the first reaction vessel 20 on the cathode side 14 of the oxygen selective ion transport membrane 12 is the supply of a second oxygen acceptance feed stream. 22 to a second reaction vessel or chamber 24 that contacts the anode side 16 of the selective oxygen transport membrane 12. The second oxygen acceptance supply stream 22 is any suitable gas stream containing hydrogen in a chemically bound state. Illustrative components for the second oxygen acceptance supply material include reagents containing hydrogen, reagents containing carbon, and combinations thereof. Very preferred are light hydrocarbons of the CxHy form, where x is between 1 and 5 e and is between 4 and 12. Methane is very preferred. Both the first oxygen donor feed stream 18 and the second oxygen acceptance feed stream 22 may also include non-reactive diluents and scavenging gases such as nitrogen, argon, steam or carbon dioxide. Since a small fraction of a steam or carbon dioxide gas inlet will react, a larger fraction of the gas inlet will not, and therefore, steam and carbon dioxide function as sweeping gases instead of gases reagents The oxygen containing molecules 26 contained within the oxygen donor feed stream 18 enter the ion transport reactor 10 through the lateral cathode inlet 28. The elemental oxygen 30 is disassociated from the oxygen containing molecules 26 in the cathode side 14 of the oxygen selective ion transport membrane 12. Elemental oxygen, in the form of oxygen ions (O ""), is transported as shown by arrow 31 through the transport membrane of selective oxygen ion 12 to the anode side 16. Oxygen depleted molecules 32 exit the transport reactor 10 through the cathode side outlet 34 as a first product stream 36, also referred to as retention, that is, the constituents retained on the cathode side 14 of the oxygen selective ion transport membrane 12. "Elemental oxygen" refers to oxygen that is not combined with other elements of the table periodical Although typically in diatomic form, the term "elemental oxygen" as used herein, is intended to encompass individual oxygen atoms, triatomic ozone, and other forms not combined with other elements. The elemental oxygen 30 in the form of oxygen ions (O ") is transported, through gaps of network structure, through the oxygen selective ion transport membrane 12 to the anode side 16. Once in the second reaction vessel 24, the elementary oxygen 30 'reacts with oxygen-consuming molecules 38 contained within the second oxygen acceptance feed stream 22. During the oxidation reactions, the oxygen ions yield electrons which are then transported as shown by the arrow 41 through the oxygen selective ion transport membrane 12 and are made available on the cathode side 14 to combine with the elemental oxygen 30 to form oxygen ions.The reaction products 42, 43 typically they include both oxygen-containing molecules 42, such as CO and CO2, and hydrogen gas 43. Reaction products 42, 43 leave the ion transport reactor 1. 0 through an anode side outlet 44 as a second product stream 46. The second product stream 46 is also referred to as the penetration, referring to constituents that include the oxygen that was transported through the transport membrane. selective oxygen ion 12. Since Figure 1 illustrates the first oxygen donor feed stream 18 and the second oxygen acceptance feed stream 22 flowing in a counter-current relationship, the concurrent flow may be applicable under certain applications . The flow velocity, that is, the transport velocity of the oxygen ion through the oxygen selective ion transport membrane 12, is driven by the differential in oxygen partial pressure (Opp) between the constituents of the first container. of reaction 20 (first Opp) and the constituents of the second reaction vessel 24 (second Opp). It is desirable to maximize the flow rate. Preferably, the differential between the first Opp and the second Opp is at least a factor of 1000, and most preferably of the order of between 1010 and 1015. For example, the first Opp can be of the order of 0.1 atmospheres, and the second Opp of the order of 10"14 atmospheres To reduce the second Opp, an easily separated diluent, or a scavenging gas, such as steam, can be included in the second oxygen acceptance feed stream 22. Alternatively, the flow rate can be electrically driven When the flow through the membrane is electrically driven, a partial pressure gradient of oxygen is not required and, therefore, for this alternative, the first Opp is not always greater than the second Opp. A process of the invention provides an effective method for increasing the production of hydrogen to control the composition of the gas in the first product stream 36 and in the second product stream 46. The prod Hydrogen uction per methane molecule can be increased by up to 50% by feeding vapor to the cathode side 14 of the oxygen selective ion transport membrane 12. Similarly, the production of carbon monoxide can be doubled by feeding C02 to the cathode. When the steam is fed to the cathode side, the reaction on the cathode side is: (4) HzO = H2 + 1 202 and the reaction on the anode side: (3) CH4 + 1'202 ^ CO + 2H2. Combining equations (3) and (4): (1) CH4 + H2O = >; CO + 3H2. When the carbon dioxide is fed to the cathode side, the reaction on the cathode side is: (5) CO2 = > CO + 1 / 2O2 and the reaction on the anode side: (3) CH4 + 1 / 2O2 = 5 CO + 2H2. Combining equations (5) and (3): (2) CH4 + H20 = > 2CO + 2H2. The decomposition of CO2 on the cathode side and the reduction of partial oxidation on the anode side both produce CO. Since CO comes from both CO2 and CH4, the molar production of CO at the outlet exceeds the molar methane entry. The anode side reactions are exothermic and require the removal of heat for steady state operation. Most heat is removed through the product gas, something is removed by heat exchange, and something is lost. Lateral cathode reactions are endothermic and provide a collector for heat removal from the anode side, thus providing heat control for the ceramic membrane reformer. The steam can be injected into the reactor at specific hot spots to increase heat removal.

In addition, the steam can optionally be preheated before it is introduced into the reactor to obtain a desired temperature level. Said vapor conditions can provide increased hydrogen production. The hot spots occur on the anode side of the membrane, where there is a leak or the local oxygen flow is high leading to areas of complete combustion, rather than partial. The opportunity to provide the removal of target heat to specific areas of the reactor should greatly improve the control of the reactor and its operation, as well as increase the operating life of the membrane providing a more uniform temperature and reduced thermal stress, a cause of failure of membrane. The control means include temperature sensors and a microprocessor in a feedback control loop that can be used to apply heat transfer techniques to adjust the local temperature levels as desired, similar to the feedback control shown in the patent of USA No. 5,547,494. The heat transfer techniques described herein adjust the heat within the reactor, as opposed to only through the walls of the reactor, thus providing a more rapid response to the thermal establishments. The reactive purge arrangements are described in "Reactive Purge for Solid Electrolyte Menbrane Gas Separation ", US patent series number 08 / 567,699, filed December 5, 1995. EP publication number 778,069, and are incorporated herein by reference.Preferred configurations for ion transport modules using a purge Reagents are described in "Solid Electrolyte Lonic Conductor Reactor Design", US Patent Application Series No. 08 / 848,204, filed April 29, 1997, and also incorporated herein by reference, both applications are commonly assigned with the present application. Total process is endothermic if all the oxygen that penetrates the membrane is obtained from H2O or CO2.A method to achieve a thermoneutral reactor is illustrated in Figure 11. O2 is added, preferably in the form of air, to the cathode side 172 of a second oxygen selective ion transport membrane 12 'Oxygen ions penetrate the second selective transport membrane of selective oxygen. and oxygen 12 'and react exothermically with methane 174 on the anode side 176. This reaction places heat in the system, since the partial oxidation reaction produces heat without endothermic decomposition of H2O or C02. Through the processes described in more detail below, a first portion of a desired product is recovered from the first product stream 36, and a second portion of the desired product is recovered from the second product stream 46. An illustrative desired product It is hydrogen gas. The sum of the first portion, recovered from the first product stream, and the second portion, recovered from the second product stream, provides a total of a desired product. The amount of the desired product received from the combination of the first portion and the second portion exceeds that which can be obtained either from the feed stream alone, and particularly from the second feed stream alone, thus providing the improved production of the product. wanted. The process of the invention will be better understood by referring to Figures 2 to 7. With reference to Figure 2, a first oxygen donor feed stream 18 is supplied to a first reaction vessel 20 on the cathode side 14 of an ion transport reactor 10. Prior to entering the first reaction vessel 20, the first donor feed stream The oxygen is preferably heated to a temperature in the range from about 600 ° C to about 1200 ° C, most preferably around 900 ° C. Any suitable means can be employed to heat the first oxygen donor feed stream 18, but preferably, to efficiently utilize the heat generated by the exothermic reactions occurring in the second reaction vessel 24, a thermal exchanger 48 thermally couples the first inlet oxygen donor feed stream 18 and second product stream 46. In a first embodiment, the first oxygen donor feed stream 18 includes steam that partially dissociates to hydrogen and oxygen ions upon contact with the transport membrane Selective oxygen ion 12. The elemental oxygen ions are transported through the oxygen selective ion transport membrane 12 to the anode side 16. The first product stream 36, containing hydrogen gas and water not dissociated, is cools through any suitable cooling medium, preferably a cam heat sink 50 which is normally coupled with the second inlet oxygen acceptance supply stream 22. A first product stream of reduced temperature 36 'is then supplied to any apparatus effective to remove most of the water 57 from the hydrogen gas. A coalescer 52 can be used. A first product stream of substantially pure hydrogen gas 36"in addition is dried through any suitable means such as adsorption drying 54 resulting in a first isolated portion 56 of the desired product, in this embodiment, hydrogen, and a waste stream 59. The first isolated portion of hydrogen 56 can be produced at high pressures by supplying steam as the first oxygen donor feed stream 18 at relatively high pressures of the order of 10 to 50 bar. , the first oxygen donor feed stream 18 can be carbon dioxide, in which case the first isolated portion is carbon monoxide In another alternative embodiment, the first oxygen donor feed stream 18 can be a contaminant such as Nox, where x is typically from 0.5 to 2. In this embodiment, the first isolated portion 56 is nitro gas geno that does not have the economic value of hydrogen gas or carbon monoxide. However, this alternative embodiment has value, since it can replace contamination control processes that might be necessary to remove Nox and add an additional value by supplying elemental oxygen to the second reaction vessel 24. Each of the alternative embodiments described above uses, as a first oxygen donor feed stream, an oxygen containing molecule that dissociates on the cathode side 14 of the oxygen selective ion transport membrane 12 and transports oxygen ions on the anode side 16 to react within the second reaction vessel 24. Also provided in the second reaction vessel 24 is a second oxygen acceptance feed stream 22 which, depending on the desired product, is either a reagent containing hydrogen, a reagent containing carbon, or a combination of these. Preferably, the second oxygen acceptance feed stream 22 is a light hydrocarbon of the CxHy form, where x is between 1 and 5. Most preferably, the second oxygen acceptance feed stream 22 is natural gas, either Wellhead or commercially produced, which contains a substantial amount of methane or methane gas. Water and carbon dioxide can also be added to the second oxygen acceptance feed stream, particularly if synthesis gas is desired. The second oxygen acceptance feed stream 22 is preferably heated before delivery to the second reaction vessel 24. The thermal coupling, through a heat exchanger 50 with the first product stream 36, is an illustrative means for heating the second Oxygen acceptance feed stream. The second preheated oxygen acceptance feed stream 22 'is then supplied to the second reaction vessel 24, where an exothermic partial oxidation reaction: (3) CH4 + 1 / 2O2 = >; CO + 2H2, form synthesis gas. The second product stream 46 leaves the second reaction vessel and is preferably cooled by any suitable means, such as through thermal coupling through the heat exchanger 48 to the first oxygen donor feed stream. Since it is preferred to optimize the production of hydrogen gas, the integration of the ion transport membrane 12 with selected processes produces either an improved desired product yield or a more economical process. As shown in Figure 3, the second product stream 46 can be provided to a combustion 58, wherein the second product stream is ignited in the presence of air 63 to generate heat 65. This heat can be used to heat other parts of process or other processes, to generate steam, or to produce electrical energy. Since no chemical product is necessary on the anode side for this mode, low quality fuels can be used as the second oxygen acceptance feed stream. If it is desired to maximize the production of hydrogen, then a hydrogen separator 60, shown in schematic lines, can receive the second product stream before supplying the combustor 58 to generate the hydrogen stream 61. Suitable hydrogen separators 60 they include PSA devices and proton-selective ion transport membranes which are described in detail below. The exhaust 62 of the combustion 58 can be cooled by any suitable means, such as the heat exchanger 64. The free water 67 is removed from the cold exhaust gas 62 ', which is then dried such as through the coalescer 66. Exhausted exhaust gas of free water 62"is further purified to recover carbon dioxide 71. Additional purification may be through amine process equipment 68, which also generates a waste stream 69. An alternative mode that increases to the maximum the production of hydrogen gas is illustrated in Figure 4. The second product stream 46 is supplied to a first water-gas displacement reactor 70. With the addition of steam 73, the following reaction occurs: (6) CO + H20 => C02 + H2 The water-gas displacement reaction is exothermic and the excess heat of the reaction can be removed to other portions of the process Optionally, a second displacement reactor or water-gas 72, shown schematically, can sequentially follow the first water-gas displacement reactor 70 and the water-gas displacement reaction conducted in two stages, since the reaction has a higher velocity at temperatures higher and a higher equilibrium conversion at lower temperatures. The water-gas displacement reaction product 74 is then cooled, such as through the heat exchanger 76 and is separated to carbon dioxide 75 and hydrogen gas 79. The purification of carbon dioxide can be by any suitable means such as using an amine process equipment 68a, which generates the waste stream 77. Any suitable hydrogen separator 60a such as PSA or a proton conducting membrane can be used to recover hydrogen gas 79. The output of hydrogen separator 76 contains hydrogen gas and carbon monoxide and has a significantly hot value. The output of the hydrogen separator 76 may be sent to a combustion to recover heat or to generate steam for the process or to be recirculated for another process, such as to the second oxygen acceptance stream 22. The output of hydrogen separator 76 may be removed to the second product stream 46 if the hydrogen and CO content of the production were sufficiently high.

Referring back to Figure 2, when steam is used as the first oxygen donor feed stream 18, and methane as the second oxygen acceptance feed stream 22, the ratio of hydrogen or carbon monoxide in the first stream of combined product 36 and second product stream 46 reaches the 3/1 ratio available in the conventional steam methane reformation. If carbon dioxide is used as the source of oxygen, the hydrogen / carbon monoxide ratio reaches a ratio of 1/1 available in the conventional methane reformation of carbon dioxide. This allows an excellent control of the stoichiometric ratio in the product gas between the two limits by controlling the vapor to carbon dioxide input ratio and the air flow input to the cathode side 14 of the ion transport reactor 10. These relationships they can also be changed by replacing another hydrocarbon with methane, however, economic benefits can generally be expected to be reduced, since methane is considered a less expensive hydrocarbon. Referring to Figure 5, the second product stream 46 can then have the hydrogen 81 removed through the hydrogen separator 60b and the carbon monoxide 83 purified through adsorption, penetration or distillation 78. The hydrogen produced and the monoxide of carbon produced, then they can be mixed at any desired ratio for any application that is desired since they were obtained separately. This mode requires the input of heat that can be obtained from any of the heat generation processes described here. If additional hydrogen is not required and carbon dioxide is a desired product, a second ion transport reactor 80 is illustrated in Figure 6, and can be used. The second product stream 46 is supplied to the anode side 82 of the selective oxygen transport membrane 84. An oxygen donor gas, such as air, is provided as a feed stream 86 to the cathode side 88. of oxygen selective ion transport membrane 84 and an exhausted stream of oxygen 95 is generated. Elemental oxygen 30 disassociated from feed stream 86 is transported through the oxygen selective ion transport membrane and provides oxygen ions. oxygen to the second product stream 46. In an exothermic reaction, the carbon monoxide contained within the second product stream 46 is converted to carbon dioxide. The stream containing carbon dioxide is then cooled such as through the heat exchanger 92 and moisture 85 is removed such as through the coalescer 66c. The carbon dioxide is further purified and / or dried, such as using the amine process equipment 68c and the carbon dioxide product 89 recovered while the waste stream 87 is typically discarded.

If the output 90 on the anode side 82 of the second ion transport reactor 80 is to be converted to synthesis gas, then the output 90 is processed in accordance with Figure 7. The output first is cooled, such as through a heat exchanger 94 and the humidity 91 is removed such as through the coalescer 66d. A dryer 54d removes substantially all of the remaining free water 92 and carbon dioxide 93 then is removed either as a waste product or as a desired product through a carbon dioxide purifier such as with the amine processing equipment. 68d. The hydrogen separator 60d produces a stream of hydrogen gas 97 as an output product. The carbon monoxide purifier 78 generates a carbon monoxide outlet 101 and a waste stream 99. Figures 3, 4 and 7 illustrate a hydrogen separator as a unit, separated from the ion transport reactor. It is within the scope of the invention to integrate the hydrogen separator with the ion transport reactor as illustrated in Figures 8 and 9 to form a combined reactor 96. The combined reactor 96 has a tubular oxygen selective ion transport membrane. 106 with a cathode side 107 and an anode side 180. A first reaction vessel or chamber 20 receives a first oxygen donor feed stream 18 'through a conduit 103., and the elemental oxygen 102 dissociated from this first oxygen donor feed stream 18 is transported through the oxygen selective ion transport membrane 106 to a second reaction vessel 24 ', which is defined by the external shell 115 and is in fluid communication with the anode side 108 of the oxygen selective ion transport membrane 106 and the anode side 98 of a proton conducting membrane 100. The elemental hydrogen 104, analogous to the elemental oxygen defined above, is hydrogen not combined with any other element of the periodic table. The elemental hydrogen is dissociated at the anode side 98 of the proton conducting membrane 100 and transported through the proton conducting membrane as hydrogen ions (protons). The protons are accumulated in a third reaction vessel 109, where they combine to form hydrogen gas as an output product 113. The proton conducting membrane 100 is any suitable material, such as palladium-based materials and ceramics, which they selectively conduct either hydrogen or protons, such as palladium-based materials and ceramics. Table 2 presents several examples of proton conductive ceramics applicable in the integrated ion / proton transport reactor 96. These materials may be in contrast to those set forth in Table 1 and in the U.S. Patents. Nos. 5,702,999 (Mazanec et al.). 5,712,220 (Carolan et al.) And 5,733,435 (Prasad et al.).

TABLE 2 Proton Conducting Materials In the combined reactor 96, both the oxygen selective ion transport membrane 106 and the proton conducting membrane 100 are preferably composite conductors, but external electrodes and an external circuit for conducting the electrons can be joined, if necessary. When the first oxygen donor feed stream 18 'is vapor, the elemental oxygen 102 is transported through the oxygen selective ion transport membrane 106 and the hydrogen remains within the first product stream 36'. The hydrogen can be separated from the first output stream 36 'through any of the processes described above or combined with the second oxygen acceptance feed stream 22' and removed through the proton conducting membrane 100. The transport of hydrogen ions from the second reaction vessel 24 'to the third reaction vessel 109 displaces the H2 / CO ratio in the second reaction vessel to carbon monoxide and increases the conversion of methane. The almost complete conversion of methane is possible using the combined reactor 96. The outlet 110 leaving the second reaction vessel 24 'consists mainly of carbon monoxide with some unconverted hydrocarbons, hydrogen, steam and carbon dioxide. Each of these products can be recovered using the processes described above. In some embodiments, it is desirable to provide a flushing gas 117 to the third reaction vessel 109 through a conduit 119 as shown in Figures 8 and 9. The relative flow rates through the membranes 100 and 106 determine the number of tubes that will be used for each type of membrane; an odd number is preferred, wherein the relative flows differ as compared to the total desired output of the combined reactor 96. An alternative process to be used with the combined reactor 96 is to feed a vapor and an air stream between the two membranes 100 and 106 to the second reaction vessel 24 '. In this configuration, both dissociation products of water, hydrogen and oxygen, could pass through the membranes. The hydrogen could be removed through the proton conductive membrane or hydrogen permeable 100 and the oxygen could be removed through the oxygen selective ion transport membrane 106, with the outer sue 108 acting as the cathode side and the internal sue 107 acting as the anode side. It is very difficult to establish an operating condition, especially the temperature, at which both membranes 100 and 106 effectively function when formed from different materials. Therefore, in one embodiment, both membranes can be formed from an individual membrane material that is permeable to both hydrogen and oxygen. An illustrative material is an electrolyte based on BaCe03. The use of an individual material for both membranes eliminates problems such as material interaction and uneven thermal expansion. In this mode, it is possible to drive electrically the conduction, since the ions H * and O "" could pass through different membranes in electrically driven systems. The vapor inlet stream may be on the cathode side 108 of the oxygen selective ion transport membrane 106 and the anode side 98 of the proton conducting membrane 100. In the parallel, separated from each tube configuration illustrated in Figure 9, the oxygen acceptance stream (CH4) is typically on the shell side of the oxygen permeable membrane tubes and the separated hydrogen permeable membrane tubes. As another alternative, if the oxygen donation stream is vapor, this vapor stream may be on the shell side. In other constructions, membranes 100 and 106 are formed as parallel, spaced plates or concentric tubes. Figure 10 schematically illustrates a process flow 112 that maximizes the hydrogen output. The forming constituents include water 114 which is steam converted by the boiler 116 to generate a vapor stream 159, which is further heated in the heat exchanger 118. A second inlet is methane 120 and a third inlet is air 122. Water 114, in the form of steam, is supplied to the cathode vessel or chamber 124 of a first ion transport reactor 126 having a selective oxygen transport membrane 12. On the cathode side 14 of the oxygen selective ion transport membrane 12, the vapor is dissociated into hydrogen and elemental oxygen 30. A mixture 128 of the undissociated vapor and the hydrogen gas at elevated temperatures is returned to the heat exchanger 118, where a portion of the heat is released content. The cooled mixture is supplied to the separator 130 and the water 132 is returned to the boiler 116 to be combined with the inlet water 114 to generate the vapor stream 159. The hydrogen portion 134 is recovered as a product. The methane 120 is supplied to the anode container or chamber 136 of the first transport reactor 126, where it reacts with the oxygen ions. The maximum amount of hydrogen is produced in the cathode chamber 124 by driving the oxidation reaction in the anode chamber 136 as quickly as possible, so that the output of the anode chamber 136 is a mixture of vapor, carbon dioxide and unreacted methane The output stream 142 can be combined with additional methane 120 and supplied to the anode side 144 of the second ion transport reactor 146, where the output stream is combined with oxygen to form combustion bases 154 which are used to provide heat for the endothermic reforming reactions in the first ion transport membrane reactor 126. After leaving the first ion transport reactor, the combustion gases 138 may be either processed to recover carbon dioxide or, alternatively, may be used to drive the gas turbine 140 to generate electric power as a by-product and / or provide additional heat for the heat exchanger 118. The air inlet 122 to the second ion transport reactor 146 is heated by the heat exchanger 118 and provided on the cathode side 148 where a portion of the oxygen 30 'contained in the air 122 is dissociated and transported through is of the oxygen selective ion transport membrane 12 '. The oxygen depleted air 150 is employed through the release of a portion of the heat contained in the heat exchanger 118. The nitrogen gas 152 can be recovered if sufficient oxygen has been removed by the 12 'ion transport membrane. Since the process 112 is predominantly exothermic, the cooling water 156 is used to regulate the temperature of the heat exchanger 118. The regulation is automatically controlled in a mode through a microprocessor, which receives the temperature data from one or more sensors arranged in the system 112. In an alternative construction, Figure 10A, a non-dissociated vapor stream 128a and oxygen from the cathode chamber 124 of the first ion transport reactor 126 Figure 10, is directed to a membrane separator of hydrogen 160. Figure 10A, having a Pd membrane or proton conducting membrane 162. The heat is recovered from the hydrogen penetration stream 163 in a portion of the heat exchanger 118a (having other streams passing through it as it is). shown in Figure 10) to produce the steam of cooled hydrogen product 165. The steam-rich retention stream 161 also gives to heat through the heat exchanger 118a and is compressed by the blower 164, so that the pressure of the compressed stream 166 is equivalent to the pressure of the vapor stream 159a. In this construction, the separator 160 replaces the separator 130 and the streams 132, 134 of Figure 10. In yet another construction (not shown), the separator 160 is placed downstream of the heat exchanger 118, Figure 10, to reduce the temperature of the stream 128a. The separator 160 is preferably disposed relative to the heat exchanger 118 to optimize the operating temperature of the membrane 162. It is recognized that the ion transport membranes and the proton transport membranes of the invention can have any desired configuration including tubes, plates and straight channels. In addition, the flow rates can be improved through the incorporation of catalysts, surface coatings or porous layers with the membranes. Catalysts such as platinum or palladium, or any other active catalyst for H2 oxidation can be used for the dissociation of H20. Likewise, an active catalyst for the oxidation of CO will be active for the dissociation of CO2. Standard reforming catalysts may also be suitable for some applications. Specific aspects of the invention are shown in one or more of the drawings only for convenience, since each aspect can be combined with other aspects according to the invention. Alternative modalities will be recognized by those skilled in the art and are intended to be included within the scope of the claims.

Claims (10)

1. A process for generating an improved production of desired product from an ion transport reactor, comprising: a) providing the ion transport reactor, having an oxygen selective ion transport membrane disposed therein, with a cathode side and anode side; b) supplying a first oxygen donor feed stream containing the desired product in a state chemically bound to a first partial oxygen pressure to said cathode side, while simultaneously supplying a second oxygen acceptance feed stream to the oxygen side. anode to establish a second partial pressure of oxygen on the anode side; c) operate the ion transport reactor with the oxygen selective ion transport membrane at an elevated temperature sufficient to facilitate the transport of oxygen through the oxygen selective ion transport membrane: d) transport the oxygen ion. elemental oxygen obtained from the first feed stream through the oxygen selective ion transport membrane so that it reacts with the second feed stream; and e) recovering the first product stream containing a first portion of the desired product from the cathode side, and recovering a second product stream from the anode side.

2. The process according to claim 1, wherein the first partial pressure of oxygen is greater than the second partial pressure of oxygen.

3. The process according to claim 2, wherein the first oxygen donor feed stream comprises at least one component selected from the group consisting of NOx, water vapor, carbon dioxide, and combinations thereof, and wherein the second oxygen acceptance feed stream comprises at least one component selected from the group consisting of hydrogen-containing reagents, carbon-containing reagents, and combinations thereof.

The process according to claim 3, wherein the second oxygen acceptance feed stream contains hydrogen in a chemically bound state and the second product stream contains a second portion of the desired product, wherein the sum of the first portion plus the second portion provides a total of the desired product, whereby the percentage of conversion to the desired product from the combination of the first portion and the second portion exceeds that which can be obtained from the second feed stream alone, thus providing said improved production of the desired product.

The process according to claim 4, characterized in that it further includes separating the hydrogen, as said desired product, from at least one of the first portion and the second portion.

The process according to claim 5, characterized in that it further includes heating the first oxygen donation feed stream to an elevated temperature before supplying the first feed stream to the cathode side.

The process according to claim 6, characterized in that it further includes passing at least a fraction of the second portion through a heat exchanger in order to provide the heat recovered from the second portion, and passing the heat recovered to the first oxygen donor feed stream in order to heat the first feed stream.

8. The process according to claim 2, characterized in that it further includes heating the selective oxygen transport membrane at an elevated temperature in an excess of 500 ° C.

The process according to claim 8, characterized in that it also includes the combustion of at least a percentage of the second portion of product and use the heat generated through said combustion to heat the ion transport membrane

10. The process according to claim 4, characterized in that it further includes supplying the second product stream to a first water-gas displacement reactor at a first temperature.