EP2519340A1

EP2519340A1 - Device and method for controlling the permeation of oxygen through non-porous ceramic membranes which conduct oxygen anions, and the use thereof

Info

Publication number: EP2519340A1
Application number: EP10795621A
Authority: EP
Inventors: Steffen Werth
Original assignee: ThyssenKrupp Uhde GmbH
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 2009-12-29
Filing date: 2010-12-15
Publication date: 2012-11-07
Also published as: DE102009060489A1; WO2011079913A1; US20130032760A1

Abstract

The invention relates to a method for controlling the permeation rate of oxygen through a non-porous ceramic membrane which conducts oxygen anions and which contains alkaline earth ions. Carbon dioxide and/or a gaseous carbon dioxide precursor is added for a specified time on at least one face of the non-porous ceramic membrane which conducts oxygen anions, said addition enabling a change in the oxygen permeability of the membrane material. This causes a reversible chemical formation of alkaline earth carbonates in the membrane and thereby changes the properties thereof for the permeation of oxygen. A membrane reactor designed with a feed line for a moderating gas can be controlled in a simple manner. The membrane reactor can be advantageously adjusted for oxidation reactions or for separating oxygen from gas mixtures.

Description

description

Apparatus and method for controlling the oxygen permeation through non-porous oxygen anions conductive ceramic membranes and their use

The present invention relates to an improved process for separating oxygen from gas mixtures by means of non-porous oxygen anion conductive ceramic membranes and to an improved reactor for carrying out chemical reactions.

It is known that non-porous oxygen anions conductive ceramic membranes can be used for the separation of oxygen from gas mixtures.

A subset of non-porous oxygen anions conductive ceramic

Membranes are oxygen anion conductive and electron conductive (mixed conducting) membranes, e.g. those with the ability to co-lead

Oxygen anions and electrons. These offer, for example, a possibility for the separation of oxygen from gas mixtures such as air.

The basic idea is a system in which a membrane is used to separate two gas chambers with different oxygen partial pressure. In operation, oxygen at the membrane becomes on the side of higher oxygen partial pressure

(Feed page) accordingly

0 ₂ + 4 e ^~ - »2 0 ^2" (1) and transported via lattice defects in the crystal structure of the material to the side of lower oxygen partial pressure (permeate side). On the permeate side, the oxygen is then correspondingly

2 O ^{2 '} -> 0 ₂ + 4 e (2) released again.

For each 0 ₂ molecule released into the reaction space on the permeate side, the charge of 4 e becomes free, which is transported counter to the direction of the oxygen ion flow to the feed side.

In mixed-conducting membranes, the charge compensation takes place by an electron conduction in the membrane material itself.

Instead of mixed conductive materials are also composite materials

Oxygen anions conductive and electron-conducting materials known in which the charge equalization via an electron-conducting second phase takes place in intimate mixture with the oxygen anions conducting material.

Also known are pure oxygen anions, such as yttria-stabilized zirconia, wherein the charge balance occurs during oxygen permeation via an external circuit.

Typically, these oxygen scavenging materials are ceramic materials which have the ability to conduct oxygen anions at temperatures typically> 600 ° C.

Such materials can be derived, for example, from the group of perovskite (ABO ₃ ) or perovskite-related structures, from the Aurivillius structures ([Βί ₂ θ ₂ ] [Α _η ιΒηΟχ]) or from the _{brownmillerite} structures (A ₂ B ₂ O ₅ ).

Typical examples of systems listed as oxygen-conducting materials in the literature are Ba (Sr) Coi _-x Fex0 _3- 5, Sr (Ba) Ti (Zr) _1-xy, Co _y Fe _x 0 ₃ 5, Lai-xSrxGai-yFeyOa-s, La _0, 5Sro, 5Mn03-6, LaFe (Ni) 03-5, Lao, 9SR _0, IFEO ₃ -S or BaCoxFe Zri _y-x. _Y oa-s. (Thursfield, IS Metcalfe, Journal of Material Science 2004, 14, 275-2485; Y. Teraoka, H. Zhang, S. Furukawa, N. Yamazoe, Chemistry Letters 1985, 1743-1746; Y. Teraoka, T. Nobunaga, K. Okamoto, N. Miura, N. Yasmazoe, Solid State Ionics 1991, 48, 207-212, J. Tong, W. Yang, B. Zhu, R. Cai, Journal of Membrane Science 2002, 203, 175 -189).

It is known that the rate of oxygen permeation in addition to the

The composition of the membrane is highly dependent on the operating conditions (T. Schiestel, M. Kilgus, S. Peter, K. J. Caspary, H. Wang, J. Caro, Journal of Membrane Science 2005, 258, 1-4).

Of particular importance here is the temperature, which generally has a linear to exponential influence on the rate of oxygen permeation.

A possible application of such membranes is the recovery of synthesis gas by partial oxidation of hydrocarbons (eg WO 2007/068369 A1). Other applications are, for example, in the recovery of oxygen-enriched air (eg DE 10 2005 006 571 A1), the oxidative dehydrogenation of hydrocarbons or hydrocarbon derivatives, the oxidative coupling of methane or the production of oxygen for power plant applications (H. Wang, Y. Cong, X. Zhu, W. Yang, React., Kinet. Catal. Lett 2003, 79, 351-356; X. Tan, K. Li, Ind. Eng. Chem. Res. 2006, 45, 142-149; R. Bredesen, K. Jordal, O. Bolland, Chemical Engineering and Processing 2004, 43, 1129-1158).

In the separation of oxygen from gas mixtures and the optionally subsequent oxidation of a gaseous reactant, for example in the synthesis of synthesis gas by the partial oxidation of hydrocarbons, a membrane reactor can be used, which is divided by a oxygen anions conductive ceramic membrane into two spaces, the so-called feed room and the permeate room. The ceramic membrane thus has a feed side and a permeate side.

In operation, on the feed side of the ceramic membrane is an oxygen-providing gas (mixture) and / or an oxygen-containing gas mixture, such as air, and on the permeate side an oxidizable medium, such as methane, optionally mixed with other components, such as water vapor can be submitted. In operation, oxygen permeates from the side of the higher oxygen partial pressure through the membrane into the permeate space and reacts with the oxidizable medium located there.

Alternatively, the oxidizable medium can be supplied to the oxygen-enriched gas mixture only after the permeate space. Since the oxygen on the permeate side is constantly reacted or removed, the oxygen partial pressure of the permeate side is below the oxygen partial pressure of the feed side.

Therefore, for example, air with a more or less arbitrary pressure can be used on the feed side, while at the same time there is a significantly increased pressure on the permeate side. The lower limit for the pressure on the feed side is that the oxygen partial pressure of the feed side must be above the oxygen partial pressure of the permeate side.

In order to achieve acceptable reaction rates and thus also integral selectivities on the permeate side in carrying out oxidation reactions, for example in the production of synthesis gas, is typically in the

Reaction space of the reactor used a suitable catalyst. Examples thereof can be found, for example, in EP 0 999 180 A2, EP 1 035 072 A1, US Pat. No. 6,077,323 or US Pat

US 6,695,983.

From US 5,240,473 A it is known that the permeability ability for oxygen anions by membranes of multi-component metal oxides at high temperatures can lose weight. This is caused by reaction of membrane constituents with carbon dioxide, water or hydrocarbons. In this patent, it is proposed to restore the permeation of the membrane by heating the membrane for a certain time to temperatures greater than 810 ° C and thus keeps above the operating temperatures of 600 to 800 ° C. Repeated heating after specified operating intervals allows the permeation capability of the membrane to be restored and thus permanently ensured.

A major problem of the described ceramic membrane reactors arises from the control of the system.

In normal operation, it can happen again and again that the

Oxygen permeation through the membrane must be varied or even temporarily brought to a standstill. A typical application for this are maintenance work on equipment components outside the membrane reactor.

Another application is the interception of temperature fluctuations in the

Membrane reactor. If, due to external influences during operation, the operating temperature is increased, the rate of oxygen permeation through the ceramic membrane increases.

As a result, the chemical reaction on the permeate side is accelerated. This reaction releases heat during exothermic reactions, causing the temperature to rise again. If such an operating condition is not intercepted by appropriate regulations, it can lead to a runaway of the membrane reactor.

In order to influence the oxygen permeation and thus the reaction in the membrane reactor, there are a number of possibilities.

For example, the operating temperature of the membrane reactor or the

Gas supply can be varied on the feed side. However, the known variants for controlling the reactor operation have significant disadvantages. For example, a cooling of the membrane reactor under certain circumstances leads to the formation of thermal stresses, whereby in particular the critical compound membrane-reactor jacket can be heavily loaded. In order to reduce these loads, it is therefore endeavored to keep the number of heating and cooling cycles of a membrane reactor as low as possible, since too many

Temperature cycles at the expense of the life of the membrane reactor goes. Likewise, a reduction of the gas supply on the feed side is problematic. As soon as the feed of the feed gas containing the oxygen is stopped, the transport of the oxygen through the ceramic membrane comes to a standstill. Since the ceramic membrane itself is a chemical compound, for example an oxygen compound, under certain circumstances this leads to a reduction of the membrane on the permeate side and thus to a destruction of the membrane material.

Object of the present invention is therefore an easy way to

Regulation of the rate of permeation of oxygen by non-porous oxygen anions to provide conductive ceramic membranes.

The present invention therefore relates to a method for controlling the permeation rate of oxygen anions through a non-porous and oxygen anions conductive ceramic membrane. The method is characterized in that a non-porous and oxygen anions-conducting ceramic membrane containing alkaline earth ions is used and that carbon dioxide and / or a gaseous carbon dioxide precursor is added to at least one side of the non-porous and oxygen-anions-conducting ceramic membrane for a predetermined time whereby a change in the oxygen permeability of the membrane material is made possible. A preferred embodiment of the method according to the invention for controlling the permeation rate of oxygen anions through a non-porous and oxygen anions-conducting ceramic membrane is characterized in that the Diaphragm on both sides surrounded by an oxygen-containing gas that contains an alkaline earth ion-containing non-porous and oxygen anions conductive

ceramic membrane is used and that at least one side of the non-porous and oxygen anions conductive ceramic membrane for a predetermined time and at temperatures between 400 and 900 ° C is contacted with gaseous carbon dioxide, so that in the non-porous and oxygen anions conductive Membrane reduces the permeation rate of oxygen anions.

Without being bound by theory, it is believed that the carbon dioxide reacts with the membrane material to form alkaline earth carbonates under the reaction conditions in the ceramic membrane. This process is reversible and the permeation rate of oxygen anions increases again as soon as carbon dioxide can no longer react with the membrane material. For the purposes of this description, the term "permeation rate of oxygen anions" is understood to mean the permeability of the ceramic membrane to oxygen per unit area and per unit of time.

The contacting of the ceramic membrane with gaseous carbon dioxide can be done in different ways. Thus, a selected amount of gaseous carbon dioxide can be added to the oxygen-containing gas for a specific time interval, or the gas containing oxygen can be added for a specific time

Time interval to be replaced by gaseous carbon dioxide. Instead of gaseous carbon dioxide, a combination of oxygen-containing gas with gaseous precursor of carbon dioxide may be used, for example gaseous

Carbon monoxide or other compounds containing gaseous carbon, such as hydrocarbons. These gaseous precursors settle under the

Conditions in the membrane reactor with the oxygen to carbon dioxide to, so that ultimately carbon dioxide comes into contact with the membrane.

The oxygen-containing gas may be for a predetermined time by gaseous carbon dioxide and / or by a mixture containing oxygen and a gaseous Carbon dioxide precursor by continuously purging the ceramic membrane with a gas stream containing carbon dioxide and / or an oxygen / carbon dioxide preblend mixture. The rinse can also be done in

predetermined periods, so pulsed done.

The membranes used according to the invention are non-porous, and due to limitations, for example in the manufacturing process, slight leaks can also occur through pores. However, it is crucial that the main effect of the separation of substances results from an interaction between the oxygen to be separated and the non-porous ceramic membrane material.

The abovementioned mixed conductors for oxygen separation are typically ceramic materials which have the capability of conducting oxygen anions at temperatures of usually> 600 ° C.

The operating temperatures for such ceramic membranes are typically above 600 ° C, preferably in the range of 700 to 900 ° C, and most preferably in the range of 800 to 900 ° C.

In a particularly preferred embodiment of the method according to the invention, the operating temperature of the ceramic membrane is set at a narrow interval, for example at an interval of ± 80 ° C, preferably ± 50 ° C, more preferably ± 30 ° C, and the permeation rate of the ceramic membrane for Oxygen is controlled by the variation of the carbon dioxide concentration on at least one side of the ceramic membrane.

Preference is given to using non-porous oxygen-anions-conducting ceramic membranes of those types which conduct both oxygen anions and also electrons. Gaseous carbon dioxide is preferably used to modulate the oxygen permeability through the ceramic membrane. Another preferred

Moderator gas is a mixture of oxygen and gaseous carbon monoxide. The shape of the non-porous oxygen anion conductive ceramic membrane may be arbitrary. These may be thin and flat membranes or preferably hollow ceramic fibers.

Any suitable material may be used as non-porous oxygen anion conductive ceramic membranes.

This is preferably an oxide ceramic with a perovskite structure or with a brownmillerite structure or with an Aurivillius structure. Preferred oxide ceramics have a perovskite structure ABO3-O, where A is bivalent and B are trivalent or higher cations, the ion radius of A is greater than the ion radius of B and δ is a number between 0.01 and 0.9, preferably between 0.01 and 0.5 to produce the electroneutrality of the material and wherein A and / or B may be present as mixtures of different cations.

Further preferred oxide ceramics have a brownmillerite structure Α2Β2θ _δ -δ, where A represents bivalent cations and B represents trivalent or higher valued cations, the ionic radius of A is greater than the ionic radius of B and δ is a number between 0.01 and 0.9, preferably between 0.01 and 0.5 to produce the electroneutrality of the material and wherein A and / or B are mixtures

different cations may be present.

In these preferred types mentioned above, the type A cations are especially selected from second main group cations, the first

Subgroup, the second subgroup, the lanthanides or mixtures of these Cations, preferably of Mg ²⁺ , Ca ²⁺ , Sr ² *, Ba ²⁺ , Cu ²⁺ , Ag ²⁺ , Zn ²⁺ , Cd ²⁺ and / or the lanthanides.

In these preferred types mentioned above, the type B cations are selected in particular from cations of the groups HIB to VIIIB of the Periodic Table and / or the Lanthanide Group, the metals of the fifth main group or

Mixtures of these cations, preferably from Fe ^3+, Fe ^{4 *} 'Ti ^3+, Ti ^+, Zr ^3+, Zr ^+, Ce ^3+, Ce ^+, Mn ^3+, Mn ^4+, Co ^2+, Co ³⁺ , Nd ³⁺ , Nd ⁴⁺ , Gd ³⁺ , Gd ⁴⁺ , Sm ³⁺ , Sm ⁴⁺ , Dy ³⁺ , Dy ⁴⁺ , Ga ³⁺ , Yb ³⁺ , Al ³⁺ , Bi ⁴⁺ or mixtures of these cations.

In a particularly preferred embodiment, the non-porous contains

Oxygen anions conductive ceramic membrane barium

Most preferably, it is a non-porous

Oxygen anion conducting ceramic membrane, which consists of BaCo _x Fe _y Zr _z 0 ₃ 5, wherein x, y and z are real numbers, x + y + z is = 1 and δ is a number of 0.01 0.9, preferably between 0.01 and 0.5 to produce the electroneutrality of the material. The inventive method can be used in any arrangements in which the rate of oxygen permeation through a non-porous oxygen anions conductive ceramic membrane must be set specifically. Particularly preferred is a method in which the non-porous oxygen anions conductive ceramic membrane is part of a membrane reactor and in which on at least one side of the membrane at predetermined time intervals or continuously a carbon dioxide and / or oxygen and carbon monoxide containing moderator gas is added, which with the non-porous oxygen anions conducting

ceramic membrane undergoes a reversible chemical reaction to form Erdalkalicarbonaten, and wherein the concentration of the moderator gas so is set, that thereby the speed of the oxygen permeating through the membrane is influenced in a desired manner.

In a particularly preferred embodiment of the method according to the invention, a moderator gas is used which forms by chemical reaction in the permeation space. This can be used to protect the membrane reactor from unwanted thermal runaway.

For example, in the case of the synthesis gas representation based on a membrane of BaCo _x Fe _y Zr _z 03-ö (x + y + z = 1) in normal operation, the amount of methane added to be matched to the oxygen permeation through the membrane, the partial Oxidation in Permetationsraum in normal operation until the formation of CO expires. In the case of an increase in the oxygen permeation, for example by an increase in the operating temperature, there is an additional formation of CO ₂ , whereby the oxygen permeation is hindered by the membrane.

A further variant of the method according to the invention consists in that a corresponding amount of moderator gas, for example CO ₂ , is continuously added to the feed stream of the non-porous, ceramic membrane on the permeate side before the reactor inlet, so that it increases with an increase in the CO ₂ concentration in the Reactor beyond the desired extent to a blocking of the membrane comes.

A further variant of the method according to the invention includes the temporally pulsed addition of the moderator gas. Depending on the duration and time interval of the moderator gas pulses, the oxygen permeation through the membrane can thus be adjusted in the time average.

A further embodiment of the invention relates to a particularly designed

Membrane reactor. This includes the following elements:

A) at least one non-porous and oxygen anions conductive ceramic

Membrane containing alkaline earth ions, which is located in a reaction space and divides it into a feed gas space and a permeate gas space, B) at least one feed line for an oxygen-containing feed gas mixture which is connected to the feed gas space,

C) at least one derivative for an oxygen depleted

Feed gas mixture which is connected to the feed gas space,

D) at least one feed line for a purge or reaction gas mixture which is connected to the permeate gas space,

E) at least one discharge for an oxygen-enriched rinsing or reaction gas mixture which is connected to the permeate gas space,

F) at least one feed line for gaseous carbon dioxide and / or for a gaseous precursor of carbon dioxide, which is connected to the feed gas space and / or the permeate gas space and / or to the feed line to the feed gas space and / or the feed line to the permeate gas space,

G) at least one control device for adjusting the content

gaseous carbon dioxide in the gas space adjacent to at least one surface of the ceramic membrane, and

H) the membrane reactor additionally comprises a sensor with which the

Permeation rate of the oxygen through the non-porous oxygen anions conductive ceramic membrane can be determined. An example of a control device G) is a mass flow controller.

In a particularly preferred embodiment, the membrane reactor additionally has I) a regulator which permits the adjustment of the content of gaseous carbon dioxide introduced into the gas space by control device G as a function of the permeation rate of oxygen detected by sensor H). Such regulators are commercially available.

The adjustment of the introduced by the control device G) in the gas space content of carbon dioxide can be done by methods known per se. For this purpose, the concentration of carbon dioxide or carbon dioxide precursor is determined. In addition to the classical methods of precipitation reactions, the C0 ₂ or C0 ₂ precursor contents in gases can also be measured by gas chromatographic measurements. This recommended for controls and slow controls. For fast-response controls, an online IR measurement is recommended for determining the content of C0 ₂ or of CO ₂ precursors, such as CO. Alternatively, the content of CO2 or CO ₂ precursor can be determined by flow measurement. The flow can be detected, for example, by measuring principles such as thermal mass flow measurement, ie by using a mass flow controller, by Coriolis mass measurement or by a variable area flowmeter.

The regulation of the CO ₂ content in the gas space, ie the adjustment of the required concentration, usually takes place via a controller controlled by software. In this case, for example, set via a controlled by software control valve, the corresponding flow. In the case of the use of a mass flow controller, the control valve with the flow measuring device is integrated in one unit.

The devices described are commercially available products. Sensor H) can be a temperature sensor with which the

Temperature in the permeate space can be measured. Increases, for example, in an exothermic oxidation reaction and at the same concentration of oxidizable

Reactant to the temperature in the permeation, this is an indication of increased oxygen permeation through the membrane. Alternatively, the

Concentration of the oxygen in the depleted feed stream from the feed space and / or the concentration of the oxidation product can be determined from the permeate space. These measured values can be used individually or in combination as controlled variables to control the coverage of the membrane surface with moderator gas. The determination of the concentration of the oxygen in the gas space or the concentration of the oxidation product in the gas space can be carried out according to the same measurement principles described above for the determination of the content of CO2 or of CO ₂ precursors in the gas space. The invention also relates to the use of the membrane reactor described above for the separation of oxygen from gas mixtures, preferably from air, or for carrying out oxidation reactions in the gas phase.

Preferably, the separated oxygen is used for the subsequent implementation of an oxidation reaction in the gas phase.

The preferred oxidation reactions are, for example, the partial oxidation of a hydrocarbon-containing gas mixture to produce synthesis gas or the oxidative dehydrogenation of hydrocarbons or the oxidative coupling of methane.

In a further preferred embodiment, the invention relates to the use of the membrane reactor described above for the production of oxygen for

Power plant applications.

The following example and figures illustrate the invention without limiting it. Show it:

FIG. 1: The rate of oxygen permeation through a membrane in FIG

Dependence on the content of C0 ₂ -moderator gas in the permeate space

FIG. 2: Area of BaC0 ₃ formation in the presence of free CO ₂ as a function of the temperature

example

In the case of a membrane based on a Ba-containing compound such as BaCo _x Fe _y Zr _z O-O (x + y + z = 1), the influence of oxygen permeation on a ceramic membrane according to the present invention (J. Tong, W. Yang Z. Shao, G. Xiong, L. Lin, Chinese Science Bulletin 2001, 46, 473-477) or Bao.sSro.sCoo.eFeo ^ Oa-ö (M. Arnold, H. Wang, A. Feldhoff, Journal of Membrane Science 2007, 293, 44-52) by adding C0 ₂ as a moderator gas on the permeate side of the membrane. As will be shown below, this addition results in a reversible reduction in oxygen permeability. A ceramic hollow fiber membrane with a diameter of 1.24 mm (T. Schiestel, M. Kilgus, S. Peter, KJ Caspary, H. Wang, J. Caro, Journal of Membrane Science 2005, 258, 1-4) flushed at a temperature of 850 ° C on the inside with 150 ml / min of air. On the outside, 30 ml / min of argon or CO2 were introduced alternately as an inert purge gas.

FIG. 1 shows the oxygen permeation obtained as a function of the C0 ₂ addition. When CO2 was added as the moderator gas, the oxygen permeation was reduced to zero within a very short period of time. As soon as the addition of CO ₂ on the permeate side was stopped, oxygen permeation increased again in as short a time.

The described effect is due to the reversible formation of BaC0 ₃ in the presence of CO2, which blocks the membrane surface and prevents oxygen permeation even at high temperatures. Once the CO ₂ concentration below the equilibrium concentration of BaC0 ₃ at the corresponding

Operating temperature drops, the BaC0 ₃ decomposes and oxygen permeation is restored.

Figure 2 shows the region of formation of BaC0 ₃ in the presence of free CO ₂ as a function of the temperature.

The amount of BaC0 _{3 formed} - and thus the extent of the reduction of

Speed of oxygen permeation - depends, among other things, on the mean partial pressure of CO2 in the gas phase. Thus, with a suitable choice of the CO 2 partial pressure, only a partial or temporary blocking of the membrane surface and thus a partial or temporary suppression of the oxygen permeation can take place. On this way For example, the effective oxygen permeation (or oxygen supply) and thus the extent of the reaction on the permeate side can be adjusted within a wide range.

Claims

claims

1. A method for controlling the permeation rate of oxygen anions through a non-porous and oxygen anions conductive ceramic membrane, characterized in that a alkaline earth metal-containing non-porous and oxygen anions conductive ceramic membrane is used and that conductive on at least one side of the non-porous and oxygen anions carbon dioxide and / or a gaseous carbon dioxide precursor is added to the ceramic membrane for a predetermined time, thereby permitting a change in the oxygen permeability of the membrane material.

2. The method according to claim 1, characterized in that the non-porous and oxygen anions conductive ceramic membrane is surrounded on both sides by an oxygen-containing gas that at least one side of the non-porous and oxygen anions conductive ceramic membrane for a

predetermined time at temperatures between 400 and 900 ° C is contacted with gaseous carbon dioxide, so that in the non-porous and

Oxygen anions conductive ceramic membrane reduces the permeation rate of oxygen anions.

3. The method according to any one of claims 1 to 2, characterized in that the gas containing oxygen on at least one side of the non-porous and oxygen anions conductive ceramic membrane gaseous carbon dioxide and / or another gaseous, carbon-containing compound is added or that the oxygen containing gas is replaced on at least one side of the non-porous and oxygen anions-conducting ceramic membrane by gaseous carbon dioxide and / or by another gaseous, carbon-containing compound. 4. The method according to any one of claims 1 to 3, characterized in that the oxygen-containing gas on both sides of the non-porous and

Oxygen anion conductive ceramic membrane different Has oxygen concentrations and that the gas with the lower

Oxygen concentration gaseous carbon dioxide and / or gaseous

Carbon monoxide is added or that the gas with the lower

Oxygen concentration is replaced for a predetermined time by gaseous carbon dioxide and / or by gaseous carbon monoxide.

Method according to one of claims 1 to 4, characterized in that the operating temperature of the ceramic membrane at an interval of ± 80 ° C is set and that the permeation rate of the ceramic

Membrane for oxygen is regulated by the variation of the carbon dioxide concentration on at least one side of the ceramic membrane.

Method according to one of claims 1 to 5, characterized in that the non-porous and oxygen anions conductive ceramic membrane a

Oxygen anions conductive and electron conductive ceramic membrane.

Method according to one of claims 1 to 6, characterized in that the non-porous and oxygen anions conductive ceramic membrane is used in the form of a ceramic hollow fiber.

Method according to one of claims 1 to 7, characterized in that the non-porous and oxygen anions conductive ceramic membrane of an oxide ceramic with perovskite structure or Brownmilleritstruktur or with

Aurivilliusstruktur is constructed.

A method according to claim 8, characterized in that the oxide ceramic has a perovskite structure ABO3-5, wherein A are divalent cations and B are trivalent or higher valent cations, the ionic radius of A is greater than the ionic radius of B and δ is a number between 0.01 and 0.9, preferably between 0.01 and 0.5, to produce the electroneutrality of the material, wherein A and / or B may be present as mixtures of different cations, and wherein at least a portion of the cations A are alkaline earth cations, or the oxide ceramics a Brownmillerite structure Α ₂ Β2θ _5- δ, where A is a divalent cation and B is a tri- or higher-valent cation, the ionic radius of A is greater than the ionic radius of B and δ is a number between 0.01 and 0.9, preferably between 0, 01 and 0.5 to produce the electroneutrality of the material, wherein A and / or B may be mixtures of different cations, and wherein at least a portion of the cations A are alkaline earth cations, in which oxide ceramics the cations of type A are preferably selected Cations of the second main group, the first subgroup, the second

Subgroup, the lanthanides or mixtures of these cations, more preferably from Mg ²⁺ , Ca ²⁺ , Sr ^{2 *} , Ba ²⁺ , Cu ²⁺ , Ag ²⁺ , Zn ²⁺ , Cd ²⁺ and / or the

Lanthanides, and wherein at least a portion of the cations A are Mg ²⁺ , Ca ²⁺ , Sr ^{2 *} and / or Ba ²⁺ , and / or wherein in these oxide ceramics, the cations of type B are preferably selected from cations of groups HIB to VI IIB of the Periodic Table and / or the Lanthanide Group, the metals of the fifth main group or mixtures of these cations, particularly preferably of Fe ³⁺ ,

Fe ⁴⁺ 'Ti ³⁺ , Ti ⁺ , Zr ³⁺ , Zr ⁴⁺ , Ce ³ ⁺ Ce ⁴⁺ , Mn ³⁺ , Mn ⁴⁺ , Co ²⁺ , Co ³⁺ , Nd ³⁺ , Nd ⁴⁺ , Gd ³⁺ , Gd ⁴⁺ , Sm ³⁺ , Sm ⁴⁺ , Dy ³⁺ , Dy ⁴⁺ , Ga ³⁺ , Yb ³⁺ , Al ³⁺ , Bi ⁴⁺ or mixtures of these cations. 10. The method according to claim 8, characterized in that the non-porous and oxygen anions conductive ceramic membrane of BaCo _x Fe _y Zr _z O3-ö, wherein x, y and z are real numbers, x + y + z = 1 mean and δ is a number between 0.01 and 0.9, preferably between 0.01 and 0.5, to produce the electroneutrality of the material.

11. The method according to any one of claims 1 to 10, characterized in that the non-porous and oxygen anions conductive ceramic membrane is part of a membrane reactor and that on at least one side of the membrane at predetermined time intervals or continuously gaseous carbon dioxide and / or gaseous carbon monoxide is added and the concentration of the

Carbon dioxide and / or carbon monoxide is adjusted so that thereby the speed of the oxygen permeating through the membrane is influenced. A method according to claim 11, characterized in that predetermined amounts of gaseous carbon dioxide and / or of gaseous carbon monoxide are added to the feed stream of the non-porous and oxygen anions-conducting ceramic membrane on the feed side and / or on the permeate side at predetermined time intervals.

Membrane reactor with the following elements:

A) at least one non-porous and oxygen anions-conducting ceramic membrane containing alkaline earth metal ions, which is located in a reaction space and divides this into a feed gas space and a permeate gas space,

B) at least one supply line for an oxygen-containing

Feed gas mixture which is connected to the feed gas space,

C) at least one derivative for an oxygen depleted

Feed gas mixture which is connected to the feed gas space,

E) at least one discharge for an oxygen-enriched scavenger or reaction gas mixture which is connected to the permeate gas space,

G) at least one control device for adjusting the content of gaseous carbon dioxide in the gas space, which adjoins at least one surface of the ceramic membrane, and

H) the membrane reactor additionally comprises a sensor with which the

Permeation rate of the oxygen through the non-porous and oxygen anions conductive ceramic membrane can be determined.

14. Membrane reactor according to claim 13, characterized in that the non-porous and oxygen anions conductive ceramic membrane is an oxygen anion-conducting and electron-conducting membrane.

15. Membrane reactor according to one of claims 13 to 14, characterized in that the membrane reactor additionally I) has a control device which controls the setting of the introduced by control device G) in the gas space gaseous carbon dioxide function of the determined by sensor H) Permeations- Oxygen permeated through the membrane.

16. Membrane reactor according to one of claims 13 to 15, characterized in that the feed line F) is connected to the side facing away from the membrane reactor side with a C0 ₂ source.

17. Membrane reactor according to one of claims 13 to 16, characterized in that the at least one non-porous and oxygen anions conductive ceramic membrane has the shape of a ceramic hollow fiber. 18 membrane reactor according to one of claims 13 to 17, characterized in that the non-porous and oxygen anions conductive ceramic membrane consists of an oxide ceramic with perovskite or Brownmilleritstruktur or Aurivilliusstruktur, preferably that the oxide ceramic has a perovskite ABO3- _Ö , wherein A divalent cations and B are trivalent or higher valent cations, the ionic radius of A is greater than the ionic radius of

B is and δ is a number between 0.01 and 0.9, preferably between 0.01 and 0.5, to produce the electroneutrality of the material and where A and / or B may be present as mixtures of different cations, or preferably that Oxide ceramic has a brownmillerite structure A2B ₂ OS- _Ö , where A is bivalent cations and B are trivalent or higher cations, the ionic radius of A is greater than the ionic radius of B and δ is a number between 0.01 and 0.9, preferably between 0 , 01 and 0.5 is the electroneutrality of the material and wherein A and / or B may be present as mixtures of different cations.

19. Membrane reactor according to claim 18, characterized in that the cations of type A are selected from cations of the second main group, the first subgroup, the second subgroup, the lanthanides or mixtures of these cations, preferably from Mg ²⁺ , Ca ²⁺ , Sr ² *, Ba ²⁺ , Cu ²⁺ , Ag ²⁺ , Zn ²⁺ , Cd ²⁺ and / or the lanthanides and / or that the cations of type B are selected from cations of groups HIB to VIIIB of the Periodic Table and / or the

Lanthanide group, the metals of the fifth main group or mixtures of these

Cations, preferably of Fe ³⁺ , Fe ⁴⁺ 'Ti ³⁺ , Ti ⁴⁺ , Zr ³⁺ , Zr ⁴⁺ , Ce ³⁺ , Ce ⁺ , Mn ³⁺ , Mn ⁴⁺ , Co ²⁺ , Co ³⁺ , Nd ³⁺ , Nd ⁴⁺ , Gd ³⁺ , Gd ⁴⁺ , Sm ³⁺ , Sm ⁺ , Dy ³⁺ , Dy ⁴⁺ , Ga ³⁺ , Yb ³⁺ , Al ³⁺ , Bi ⁴⁺ or mixtures of these cations. 20. Membrane reactor according to claim 18, characterized in that the non-porous and oxygen anions conductive ceramic membrane of BaCo _x Fe _y Zr _z 0 _3rd ₅ , where x, y and z are real numbers, x + y + z = 1 and δ is a number between 0.01 and 0.9, preferably between 0.01 and 0.5, to the electroneutrality of the material manufacture.

21. Use of a reactor according to any one of claims 13 to 20 for the separation of oxygen from gas mixtures, in particular from air or for carrying out oxidation reactions in the gas phase. 22. Use according to claim 21, characterized in that the separated oxygen is used for the subsequent implementation of an oxidation reaction in the gas phase, preferably in an oxidation reaction, which is a partial oxidation of a hydrocarbon-containing gas mixture for the synthesis gas, or an oxidative dehydrogenation of Hydrocarbons, or is an oxidative coupling of methane.

23. Use according to claim 21, characterized in that the separated oxygen is used for power plant applications.