EP4633777A1

EP4633777A1 - Flameless combustion heating of oxygen separation membrane

Info

Publication number: EP4633777A1
Application number: EP23825472.6A
Authority: EP
Inventors: Bolaji OLAYIWOLA; Vasily Simanzhenkov; Shahin Goodarznia
Original assignee: Nova Chemicals International SA
Current assignee: Nova Chemicals International SA
Priority date: 2022-12-12
Filing date: 2023-12-06
Publication date: 2025-10-22
Also published as: MX2025006189A; WO2024127171A1

Abstract

Systems and methods for heating an oxygen transport membrane in an oxygen separation module are provided. An exemplary oxygen separation module includes an oxygen transport membrane housed inside a sealed vessel and having a retentate side and a permeate side, a first inlet for introducing feed from the distillation top outlet, combustible fuel, or both into the retentate side. The oxygen separation module has a second inlet for introducing feed from a distillation top outlet, combustible fuel, or both into the permeate side, an air inlet for introducing air into the retentate side. The oxygen separation module includes a flameless combustor to heat the oxygen transport membrane, an exhaust for discharge of oxygen depleted air, combustion products from the retentate side, or both, and an outlet for removing oxygen enriched gas and combustion products from the permeate side.

Description

FLAMELESS COMBUSTION HEATING OF OXYGEN SEPARATION MEMBRANE

TECHNICAL FIELD

The present disclosure is directed to the use of a high-temperature oxygen separation membranes. More specifically, a flameless combustion unit is used to heat the oxygen separation membrane.

BACKGROUND ART

Olefins like ethylene, propylene, and butylene, are basic building blocks for a variety of commercially valuable polymers. Since naturally occurring sources of olefins do not exist in commercial quantities, polymer producers rely on methods for converting the more abundant lower alkanes into olefins. The method of choice for today's commercial scale producers is steam cracking, a highly endothermic process where steam-diluted alkanes are subjected very briefly to a temperature of at least 800°C. The fuel demand to produce the required temperatures and the need for equipment that can withstand that temperature add significantly to the overall cost. In addition, the high temperature promotes the formation of coke, which accumulates within the system, resulting in the need for costly periodic reactor shutdown for maintenance and coke removal.

Selective oxidation processes, such as oxidative dehydrogenation (ODH), are an alternative to steam cracking that are exothermic and produce little or no coke. In ODH, a lower alkane, such as ethane, is mixed with oxygen in the presence of a catalyst and optionally an inert diluent, such as carbon dioxide or nitrogen or steam, in some examples at temperatures as low as 300°C, to produce the corresponding alkene. In some examples, various other oxidation products may also be produced in this process.

A portion of the oxygen can be provided by a membrane separator on the final effluent stream. The membrane separator is operated at a high temperature, e.g., 800°C, to allow oxygen to pass from a retentate side to a permeate side. The stream from the permeate side can then be recycled to the reactor inlet

SUMMARY OF INVENTION

An embodiment described in examples herein provides a chemical complex for oxidative dehydrogenation of lower alkanes. The chemical complex includes at least one oxidative dehydrogenation reactor, comprising an oxidative dehydrogenation catalyst and designed to accept, an oxygen containing gas and a lower alkane containing gas. The oxidative dehydrogenation reactor produces a product stream comprising a corresponding alkene and one or more of unreacted lower alkane, oxygen, inert diluent, carbon oxides, including carbon dioxide and carbon monoxide, oxygenates, including but not limited to, one or more of acetic acid, acrylic acid and maleic acid, and water. The chemical complex also includes a quench tower for quenching the product stream and for removing water and soluble oxygenates from the product stream, an amine wash for removing carbon dioxide from the product stream, a dryer for removal of water from the product stream, a distillation tower for removing C2/C2+ hydrocarbons from the product stream to produce an overhead stream enriched with Cl hydrocarbons and any other compounds lighter than C2/C2+ hydrocarbons. The chemical complex further includes an oxygen separation module including an oxygen transport membrane housed inside a sealed vessel and having a retentate side and a permeate side, a first inlet for introducing the overhead stream, combustible fuel, or both into the retentate side, and a second inlet for introducing the overhead stream, combustible fuel, or both into the permeate side. The oxygen separation module includes an air inlet for introducing air into the retentate side, a flameless combustor to heat the oxygen transport membrane, and an exhaust for discharge of oxygen-depleted air, combustion products from the retentate side, or both. The oxygen separation module also includes an outlet for removing oxygen enriched gas and combustion products from the permeate side. The components of the chemical complex, as listed above, are connected in series in the sequence described. The overhead stream from the distillation tower is directed into the retentate side of the oxygen separation module, the permeate side of the oxygen separation module, or both the retentate side and the permeate side of the oxygen separation module, and the oxygen enriched gas and combustion products from the permeate side of the oxygen separation module is directed back to the oxidative dehydrogenation reactor.

Another embodiment described by examples herein provides an oxygen separation module. The oxygen separation module includes an oxygen transport membrane housed inside a sealed vessel and having a retentate side and a permeate side, a first inlet for introducing feed from the distillation top outlet, combustible fuel, or both into the retentate side. The oxygen separation module has a second inlet for introducing feed from a distillation top outlet, combustible fuel, or both into the permeate side, an air inlet for introducing air into the retentate side. The oxygen separation module includes a flameless combustor to heat the oxygen transport membrane, an exhaust for discharge of oxygen depleted air, combustion products from the retentate side, or both, and an outlet for removing oxygen enriched gas and combustion products from the permeate side.

Another embodiment described by examples herein provides a method for heating an oxygen separation membrane. The method includes mounting a flameless combustion unit in an oxygen separation module, introducing an oxidant gas and fuel proximate to the flameless combustion unit, and combusting the oxidant gas and fuel with the flameless combustion unit to heat the oxygen separation membrane.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a simplified process flow diagram of a chemical complex used for the production of ethylene in an oxidative dehydrogenation (ODH) reaction, in accordance with examples.

Figure 2A is a cross-sectional view of an oxygen separation membrane with a flameless combustion layer on a retentate side for heating of the oxygen separation membrane.

Figure 2B is a cross-sectional view of an oxygen separation membrane with a flameless combustion layer on a permeate side for heating of the oxygen separation membrane.

Figure 3A is a schematic drawing of an oxygen separation module where a hydrocarbon fuel is provided to the permeate side.

Figure 3B is a cross-section of an oxygen separation module through the dotted line in Figures 3A.

Figure 4A is a front view of a flameless combustion nozzle.

Figure 4B is a perspective view of the flameless combustion nozzle.

Figure 5A is a schematic drawing of an oxygen separation module where a hydrocarbon fuel is provided to the retentate side.

Figure 5B is a schematic drawing of an oxygen separation module in which the feed and a hydrocarbon fuel can be directed to both the permeate side and the retentate side using a valve module.

Figure 6 is a process flow diagram of a method for heating an oxygen separation membrane.

DESCRIPTION OF EMBODIMENTS

Oxygen separation membranes have a high operating temperature, e.g., at least 800°C, to allow oxygen to pass through the membrane from a retentate side to a permeate side. However, to achieve the operating temperatures requires combustion of residual hydrocarbons formed in the reaction, or fuel added to the effluent stream. Combustion may lead to the formation of hotspots along the oxygen separation membrane, which may lead to damage or failure of the oxygen separation membrane. Techniques described in examples herein provide for heating the oxygen separation membrane using a flameless combustion process. The flameless combustion process evenly reacts the fuel and oxygen, both lowering the temperature of the combustion process and reducing the possibility of the formation of hotspots. As described herein the flameless combustion is performed by a flameless combustion unit that uses either a catalytic layer in close proximity to the oxygen separation membrane or a flameless combustion nozzle that provides for the separation of fuel and oxidizer, allowing for a slower reaction.

Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties, which the present disclosure desires to obtain. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

In addition, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of 1 to 10 is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations.

As used herein, the term “alkane” refers to an acyclic saturated hydrocarbon. In many cases, an alkane consists of hydrogen and carbon atoms arranged in a linear structure in which all of the carbon-carbon bonds are single bonds. Alkanes have the general chemical formula CnH2n+2. In many examples of the disclosure, alkane refers to one or more of methane, ethane, propane, butane, pentane, hexane, octane, decane, and dodecane. In particular examples, alkane refers to ethane and propane.

As used herein, the term “alkene” refers to unsaturated hydrocarbons that contain at least one carbon-carbon double bond. In many examples, alkene refers to alpha olefins. In many examples of the disclosure, alkene refers to one or more of ethylene, propylene, 1- butene, pentene, pentadiene, hexene, octene, decene, and dodecene. Further, as used herein, the term includes other compounds with carbon-carbon double bonds, such as butadiene, among others. In particular examples, alkene refers to ethylene and propylene and, in some examples, ethylene.

As used herein, the terms “alpha olefin” or “a-olefin” refer to a family of organic compounds, which are alkenes (also known as olefins) with a chemical formula CnFbn, distinguished by having a double bond at the primary or alpha (a) position. In many examples of the disclosure, alpha olefin refers to one or more of ethylene, propylene, 1- butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 1-dodecene. In particular examples, alpha olefins refer to ethylene and propylene and, in some examples, ethylene.

As used herein, the term “essentially free of oxygen” means the amount of oxygen present, if any, remaining in a process stream after the one or more ODH reactors, and in many examples after the second reactor as described herein, is low enough that it will not present a flammability or explosive risk to the downstream process streams or equipment. For example, it may be less than 1000 vol. % oxygen, less than 100 vol. % oxygen, or lower.

As used herein, a “flameless combustor” or a “flameless combustion unit” includes a flameless combustion layer disposed proximate to an oxygen transport membrane or a flame less combustion nozzle.

As used herein, the term “fixed bed reactor” refers to one or more reactors, in series or parallel, often including a cylindrical tube filled with catalyst pellets with reactants flowing through the bed and being converted into products. The catalyst in the reactor may have multiple configurations including, but not limited to, one large bed, several horizontal beds, several parallel packed tubes, and multiple beds in their own shells.

As used herein, the term “fluidized bed reactor” refers to one or more reactors, in series or parallel, often including a fluid (gas or liquid) which is passed through a solid granular catalyst, which can be shaped as tiny spheres, for example, less than 200 micrometers in diameter, at high enough velocities to suspend the solid and cause it to behave as though it were a fluid. As used herein, the term “MoVOx catalyst” refers to a mixed metal oxide having the empirical formula Moe.s-.oViOci. where d is a number to at least satisfy the valence of any present metal elements; a mixed metal oxide having the empirical formula Mo6.25-7.25V3Oa, where d is a number to at least satisfy the valence of any present metal elements, or combinations thereof.

As used herein, the term, “selective oxidation” or “SO” refers to an oxidation process that does not proceed to complete thermodynamic oxidation, for example, stopping at products more complex than carbon dioxide and water. As used herein, “oxidative dehydrogenation” or “ODH” is a subset of selective oxidation, and refers to processes that couple the endothermic dehydrogenation of an alkane with the strongly exothermic oxidation of hydrogen as is further described herein.

In some examples disclosed herein, the degree to which carbon monoxide is produced during an SO process can be mitigated by converting it to carbon dioxide, which can then act as an oxidizing agent. The process can be manipulated to control the output of carbon dioxide from the process to a desired level. Using the methods described herein, a user may choose to operate in carbon dioxide neutral conditions such that surplus carbon dioxide need not be flared or released into the atmosphere.

ODH Process

Use of the ODH reactor as described in the chemical complex of the present disclosure falls within the knowledge of the person skilled in the art. For best results, the oxidative dehydrogenation of a lower alkane may be conducted at temperatures from 300°C to 550°C, from 300°C to 500°C, or from 350°C to 450°C, at pressures from 0.5 to 100 psi (3.447 to 689.47 kPa), or from 15 to 50 psi (103.4 to 344.73 kPa), and the residence time of the lower alkane in the reactor is typically from 0. 12 to 7.2 seconds, 0.002 to 30 seconds, or from 1 to 10 seconds.

The lower alkane containing gas is ideally of a purity greater than 95%, most preferably, 98%. In an example of this disclosure, the process includes the addition of an ethane containing gas of purity of preferably, 95%, most preferably, 98%.

In various examples, the process has a selectivity for the corresponding alkene (ethylene in the case of ethane ODH) of greater than 95% or greater than 98%. The gas hourly space velocity (GHSV) will be from 500 to 30000 h’¹, or greater than 1000 h’¹. The space-time yield of corresponding alkene (productivity) in g/hour per kg of the active catalyst is greater than 900, or greater than 1500, or greater than 3000, or greater than 3500 at 350°C to 400°C. It should be noted that the productivity of the catalyst will increase with increasing temperature until the selectivity is sacrificed.

When the lower alkane is ethane, the specificity of conversion to ethylene is greater than 80%, greater than 90%, greater than 95% or higher.

Mixtures of oxygen and hydrocarbon may cause issues with uncontrolled reactions. For that reason, mixtures of a lower alkane with oxygen should comprise ratios that fall outside of the flammability envelope. The examples described herein contemplates a ratio of alkane to oxygen that is above an upper flammability envelope. In this instance, the percentage of oxygen in the mixture is less than 30%, less than 25%, or less than 20%. With higher oxygen percentages, alkane percentages and diluent percentage are selected to keep the mixture outside of the flammability envelope, either above the upper limit or below the lower limit. While a person skilled in the art would be able to determine an appropriate level, generally the percentage of alkane are less than 40%. In examples for which the mixture of gases prior to introduction to the ODH reactor includes 20% oxygen and 40% alkane, the balance is made up of an inert diluent, such as nitrogen, carbon dioxide, or steam. The inert diluent should exist in the gaseous state in the conditions within the reactor and should not increase the flammability of the hydrocarbon added to the reactor. As described herein, the inertness of the diluent is with respect to flammability only, it can be noted that some inert diluents, such as CO2, can participate in the ODH reaction. The inert diluent can be added to either of the lower alkane containing gas or the oxygen containing gas prior to entering the ODH reactor or may be added directly into the ODH reactor.

While the present disclosure contemplates use of ratios of lower alkane to oxygen that do not equal or approximate 1 : 1, generally the addition of each is close to 1 : 1. In some embodiments, it is 2: 1, 3: 1, or higher. A higher conversion rate is obtained under stoichiometric conditions, where the goal is 100% conversion, leaving minimal unreacted alkane and oxygen in the effluent stream from the ODH reactor. When the components are added in an unbalanced ratio, oxygen or unreacted alkane will be present in the product stream. In one example, the product stream leaving the ODH reactor contains less than 5% unreacted lower alkane, less than 2.5%, or less than 1%. In another example, the product stream leaving the ODH reactor contains less than 2% oxygen, less than 1.5% oxygen, or less than 1% oxygen.

The ratio of oxygen to lower alkane added to the ODH reactor also effects the composition of by-products in the effluent stream leaving the ODH reactor. Excess oxygen may oxidize the corresponding alkene to a carboxylic acid. For example, ethylene produced in the ODH reactor may be further oxidized to acetic acid.

Removal of by-products such as oxygenates, for example, acetic acid, is performed in downstream units. The quench tower is primarily used to reduce the temperature of the effluent stream, but is also used to isolate oxygenates and water produced in the ODH reactor. The cooling of the effluent stream results in condensation of oxygenates at a much higher temperature than the dew point of the alkanes or the corresponding alkene gases. The difference in the dew points allows the gaseous remains to move on to the next step in the separation of by-products from the product stream. Captured oxygenates may be used in other well-known downstream processes. For example, in the ODH of ethane to ethylene, the ethylene may be further oxidized to acetic acid, which may be reacted with ethylene to produce vinyl acetate or other oxygenates. The process is described further with respect to Figure 1.

Figure 1 is a simplified process flow diagram of a chemical complex 100 used for the production of ethylene in an oxidative dehydrogenation (ODH) reaction. In this example, the chemical complex 100 includes an ODH reactor 102, a scrubber 104, a second reactor 106, an amine wash system 108, a dryer 110, a distillation tower 112, and an oxygen separation module 114. It can be understood that each of these units may include one or more vessels and supporting equipment, such as valves, pumps, sensors, and associated control equipment, such as distributed control systems, and the like.

The arrangement of these units is not limited to that shown in Figure 1. In some examples, the second reactor 106 is not placed directly downstream of the scrubber 104, but is placed further downstream. Depending on the installation environment, not all of the units shown may be present. Further, additional units may be present, for example, a compressor may be placed upstream of the second reactor 106 to increase the pressure of the feed. In some examples, multiple ODH reactors are used in a parallel configuration.

The ODH reactor 102 may be a fixed bed reactor or a fluidized bed reactor. The ODH reactor 102 includes an ODH catalyst capable of catalyzing the oxidative dehydrogenation of alkanes introduced through an alkane line 116. The ODH catalyst may include any number of mixed metal oxide catalysts known to catalyze an ODH reaction, including catalysts containing molybdenum (Mo), vanadium (V), tellurium (Te), and tantalum (Ta), or any combinations thereof. Examples of ODH catalysts that can be used include: catalysts of the formula: MoaViTe_cNb</PdeOf where a, b, c, d, e and f are the relative atomic amounts of the elements Mo, V, Te, Nb, Pd and O, respectively; and when a = 1, b = 0.01 to 1.0, c = 0.01 to 1.0, d = 0.01 to 1.0, 0.00 < e < 0.10 and f is a number to at least satisfy the valence state of the metals in the catalyst; catalysts of the formula:

NigA/jB/DyO/ where g is a number from 0. 1 to 0.9, in many cases from 0.3 to 0.9, in other cases from 0.5 to 0.85, in some instances 0.6 to 0.8; h is a number from 0.04 to 0.9; i is a number from 0 to 0.5; j is a number from 0 to 0.5; and f is a number to at least satisfy the valence state of the catalyst; A is chosen from Ti, Ta, V, Nb, Hf, W, Y, Zn, Zr, Si and Al or mixtures thereof; B is chosen from La, Ce, Pr, Nd, Sm, Sb, Sn, Bi, Pb, Tl, In, Te, Cr, Mn, Mo, Fe, Co, Cu, Ru, Rh, Pd, Pt, Ag, Cd, Os, Ir, Au, Hg, and mixtures thereof; D is chosen from Ca, K, Mg, Li, Na, Sr, Ba, Cs, and Rb and mixtures thereof; and O is oxygen; catalysts of the formula:

MOHEAG/0/ where E is chosen from Ba, Ca, Cr, Mn, Nb, Ta, Ti, Te, V, W and mixtures thereof; chosen from Bi, Ce, Co, Cu, Fe, K, Mg, V, Ni, P, Pb, Sb, Si, Sn, Ti, U, and mixtures thereof; a = 1; k is 0 to 2; 1 = 0 to 2, wherein the total value of 1 for Co, Ni, Fe and mixtures thereof is less than 0.5; and f is a number to at least satisfy the valence state of the metals in the catalyst; catalysts of the formula:

VmMonNboTe^Me_?O/ where Me is chosen from Ta, Ti, W, Hf, Zr, Sb and mixtures thereof; m is from 0. 1 to 3; n is from 0.5 to 1.5; o is from 0.001 to 3; p is from 0.001 to 5; q is from 0 to 2; and fis a number to at least satisfy the valence state of the metals in the catalyst; and catalysts of the formula:

MoXXYZMO/ where X is at least one of Nb and Ta; Y is at least one of Sb and Ni; Z is at least one of Te, Ga, Pd, W, Bi and Al; M is at least one of Fe, Co, Cu, Cr, Ti, Ce, Zr, Mn, Pb, Mg, Sn, Pt, Si, La, K, Ag and In; a=1.0 (normalized); r = 0.05 to 1.0; s = 0.001 to 1.0; t = 0.001 to 1.0; u = 0.001 to 0.5; v = 0.001 to 0.3; and f is a number to at least satisfy the valence state of the metals in the catalyst. a mixed metal oxide having the empirical formula:

M06.5-7.oV30d where d is a number to at least satisfy the valence of the metals in the catalyst. a mixed metal oxide having the empirical formula:

MO6.25-7.25V3Od where d is a number to at least satisfy the valence of the metals in the catalyst.

In addition to the examples shown, any number of other catalyst systems may be used. In some examples, the catalyst may be supported on/agglomerated with a binder. Some binders include acidic, basic or neutral binder slurries of TiCh, ZrCh AI2O3, A10(0H), and mixtures thereof. Another useful binder includes Nb2C>5. The agglomerated catalyst may be extruded in a suitable shape, such as rings, spheres, or saddles, among others, of a size typically used in fixed bed reactors. When the catalyst is extruded, various extrusion aids known in the art can be used. In some cases, the resulting support may have a cumulative surface area of less than 35 m²/g as measured by BET, in some cases, less than 20 m²/g, in other cases, less than 3 m²/g. and a cumulative pore volume from 0.05 to 0.50 cm³/g.

The reaction takes place in the presence of oxygen, which may be introduced through a feed line 118. The feed line 118 may be a single feed line with a combination of the feed stocks, or may be divided into any combinations of a light hydrocarbon feed line, a carbon dioxide feed line, and a steam feed line. The ODH reaction may also occur in the presence of an inert diluent, such as carbon dioxide, nitrogen, or steam. The inert diluent is added to the mixture to lower the flammability of the mixture during the ODH reaction, or to add additional reactants for the ODH reaction used to produce acetic acid, as described herein. In some examples, all of the reactants are added through the feed line 118. In these examples, upstream equipment may be used to blend the reactants below flammability limits prior to introduction to the ODH reactor 102.

In some examples, a flooded gas mixer is used to allow mixing of the gases while they are surrounded by a non-flammable liquid, such as water. In these examples, the alkane line 116, the feed line 118, and recycle lines, as described herein, may be coupled to the flooded gas mixer for mixing, wherein the gas mixture from the flooded gas mixer is fed to the ODH reactor 102.

The ODH reaction that occurs within the ODH reactor 102 may also produce a variety of other products in addition to ethylene and other target olefins. The other products may include carbon dioxide, carbon monoxide, oxygenates, such as acetic acid, and water. These reaction products from the ODH reactor 102 are carried by the ODH effluent line 120 to the scrubber 104 along with unreacted alkane, the corresponding reacted alkene, residual oxygen, carbon monoxide, and inert diluent. The scrubber 104 quenches the products in the effluent from the ODH reactor 102 for the removal of oxygenates and water through the scrubber bottom outlet 122.

The gases that are separated from the reaction products exit the scrubber 104 through the scrubber overhead line 124. The gases may include unconverted alkanes, corresponding alkanes, unreacted oxygen, carbon dioxide, carbon monoxide, and inert diluent. These gases may be directed to the second reactor 106 through an ODH control valve 126 for further processing. In some examples, a gas-recycling valve 128, shown as closed in Fig. 1, may be used to recycle a portion of the gases to be combined with the gases from the fresh feed lines 116 and 118 through a recycling line 130.

In this example, the second reactor 106 contains a catalyst with a group 11 metal, for example, with a promoter and support, to react oxygen in the gases with carbon monoxide to form carbon dioxide. The second reactor 106 may be a fixed bed reactor or a fluidized bed reactor. Further, the catalyst can react acetylene with oxygen to reduce or eliminate it. The carbon dioxide from the second reactor 106 can be recycled to the ODH reactor 102 through a recycling line 132.

The remaining gases, including a portion of the carbon dioxide, unconverted lower alkanes, the corresponding alkenes, and any other remaining materials are conveyed to the amine wash system 108 through a products line 134. The amine wash system 108 may include an absorber tower in which the gases are contacted with a lean amine, such as diethanolamine, monoethanolamine, or methyldiethanolamine, among others. Any carbon dioxide in the gases is then captured by reaction with the lean amine. After the amine captures the carbon dioxide, it is termed a rich amine. The rich amine is sent to a regenerator in which the carbon dioxide is removed from the rich amine, providing the lean amine that is returned to the absorber tower of the amine wash system 108, and a carbon dioxide stream. The carbon dioxide stream exits the amine wash system 108 through a carbon dioxide outlet 136. In some examples, the carbon dioxide is recycled back to the ODH reactor 102 or sold as a product stream. Components of the gases that are not absorbed in the amine wash system 108 exit through an absorber overhead line 138, which conducts the components to the dryer 110.

In various examples, the dryer 110 is a multistage chiller and cryogenic dryer that removes water through a condensation process in a first stage, and then successively removes remaining amounts of water in following stages. In other examples, the dryer 110 is an absorption dryer, which absorbs water by flowing the gases through zeolites or other materials. The dried gas is conducted from the dryer 110 through a dry gas line 140 to the distillation tower 112.

The distillation tower 112 may include a single vessel or multiple vessels that perform cryogenic separations. In the distillation tower 112, C2/C2+ hydrocarbons are separated and removed through a distillation bottom outlet 142. The remaining gases include mainly methane, inert diluent, such as nitrogen, and any remaining carbon monoxide. These gases leave the distillation tower through a distillation top outlet 144 and flow to the oxygen separation module 114.

In this example, the oxygen separation module 114 includes a sealed vessel having a retentate side 146 and a permeate side 148, separated by an oxygen transport membrane 150. As shown, the gases from the distillation top outlet 144 may be directed either to the retentate side 146 or the permeate side 148. In some examples, flow controllers may be included to allow for flow into both sides at varying levels, as discussed with respect to Figure 5B. For example, an operator may choose what portion of the flow from the distillation top outlet 144 enters the retentate side 146 and what portion enters the permeate side 148. Depending upon conditions, an operator may switch between the two sides, allow equivalent amounts to enter each side, or bias the amount directed to one of the two sides.

The oxygen separation module 114 also includes an air input from an air line 152 to introduce an oxygen-containing gas into the retentate side 146. Combustion of products in the gases from the distillation top outlet 144 may then heat the oxygen transport membrane 150 to greater than about 850°C, allowing oxygen to pass from the retentate side 146 to the permeate side 148. The oxygen transport membrane 150 blocks other components, besides oxygen, which exit the retentate side 146 of the oxygen separation module 114 through an exhaust 154.

Accordingly, the oxygen separation module 114 provides an oxygen enriched gas from the permeate side 148 that exits the oxygen separation module 114 through an oxygen return line 156. The oxygen return line 156 is then coupled to the feed line 118, or upstream blending equipment, for return to the SO reactor 102. When the gases from the distillation top outlet 144 are directed into the retentate side 146, the concentration of the oxygen in the oxygen return line 156 can approach 99%. When the gases from the distillation top outlet 144 are directed into the permeate side 148, the concentration of the oxygen in the oxygen return line 156 may be about 80% to about 90%, with the remaining gases being carbon dioxide, water, and inert diluent. If the combustion of products in the gases from the distillation top outlet 144 are not sufficient to raise the oxygen transport membrane 150 to the operating temperature, fuel may be added through a fuel line 158.

The ODH downstream separation processing taking place in vessels 106, 108, 110, 112, and 114, and their associated equipment, may be grouped into an ODH system 160, as shown in Figure 1. As described herein, the ODH control valve 126 may direct at least a portion of the gases from the scrubber overhead line 124 to the ODH system 160 for further processing, for example, to sell C2/C2+ from the distillation bottom outlet 142 as a product. The gas-recycling valve 128, shown as closed in Figure 1, can be used in other examples to recycle at least a portion of the gases to the fresh feed lines through a recycling line 130, as described herein.

Figure 2A is a cross-sectional view of an oxygen transport membrane 202 including a flame less combustion layer 204 on a retentate side 146 for heating of an oxygen separation membrane 206. Like numbered items are as described with respect to Figure 1. As fuel and oxygen travel down the retentate side 146, they are reacted at, or in, the flame less combustion layer 204. As used herein, “flameless combustion” is a lower temperature, or mild combustion, process in which the temperature of the combustion products is less than about 2000°C, or less than about 1500°C, less than about 1000°C, or about 900°C. The temperature of the flameless combustion is sufficient to heat the oxygen separation membrane 206 to a temperature of at least about 850°C, allowing oxygen to transfer across the oxygen separation membrane 206. The lower combustion temperatures also decrease the formation of including materials such as NOx.

In the examples shown in Figures 2A and 2B, the flameless combustion layer 204 is disposed proximate to the oxygen separation membrane 206. In some examples, the flameless combustion layer 204 is in direct contact with the oxygen separation membrane 206. The flameless combustion layer 204 can include any number of materials, such as a wire mesh made from tungsten or stainless steel. In other examples, the flameless combustion layer 204 is a ceramic, such as cerium oxide, among others. In some examples, the flameless combustion layer 204 includes catalytic sites to lower the activation temperature of the reaction, making the initiation of the combustion possible without substantially heating the feed gases.

In various example, the oxygen separation membrane 206 is a porous titanium mesh, or a peroskovite material, triple ionic-electronic conductors (TIECs), among others. Oxygen permeable ceramic dense membranes can be composed of different structures like perovskites (ABOs), fluorites (AO2), brownmillerites (A2B2O5), pyrochlores (A2B2O7), and Ruddle sden-Popper series (A_n+iB_n03_n+i). All these materials can conduct oxygen ions through their crystal lattice. Among all materials, perovskites and fluorites are the most studied as oxygen membranes. Perovskites are the most attractive materials since they conduct both oxygen ions and electrons, and are commonly well-known in their extended form as mixed ionic electronic conductors (MIEC). The oxygen separation membrane 206 is discussed further with respect to Figure 3A.

Figure 2B is a cross-sectional view of an oxygen transport membrane 208 with a flameless combustion layer 204 on a permeate side 148 for heating of the oxygen separation membrane. Like numbered items are as described with respect to Figures 1 and 2A. The flameless combustion layer 204 is disposed on the side that is exposed to fuel and oxygen. In some examples, the fuel is added to the permeate side 148, and thus the flameless combustion layer 204 would be disposed proximate to the oxygen separation membrane 206 on the permeate side 148 of the oxygen transport membrane 208.

The oxygen transport membrane is not limited to the examples shown in Figures 2A and 2B. In examples in which fuel and oxygen are present on both the permeate side 148 and retentate side 146, such as when a flow controller is used to divide the flow between the permeate side 148 and the retentate side 146, a flameless combustion layer 204 can be located on both sides of the oxygen separation membrane 206. The oxygen separation module 114 using the oxygen transport membrane 202 or 208, as described with respect to Figure 2A and Figure 2B, is depicted schematically in Figures 3A, 3B, 5A, and 5B.

Figure 3 A is a schematic drawing of an oxygen separation module 114 where a hydrocarbon fuel is provided to the permeate side 148. Like numbered items are as described with respect to Figures 1, 2A, and 2B. In this example, the oxygen transport membrane 208 is a tube that fits inside a larger tube 302, which forms the outer wall of oxygen separation module 114. As described herein, the annular space between the larger tube 302 and the oxygen transport membrane 208 corresponds to the retentate side 146, while the space within the oxygen transport membrane 208 corresponds to the permeate side 148. Material suitable for construction of the larger tube 302 include those resistant to temperatures that exceed 850°C and approach 1000°C, such as high-temperature stainless steel, titanium, and the like.

The oxygen separation membrane 206 component of the oxygen transport membrane 208 selectively allows passage of oxygen when the membrane reaches a critical temperature. As described above the oxygen separation membrane 206 may be a peroskovite, which is a mixed ionic -electronic conducting (MIEC) type of membrane. In some examples, the peroskovite has the chemical formula BaCoxFeyZrzOs, although any number of membrane formulations may be used. Movement of oxygen across the oxygen separation membrane 206 is driven by an oxygen partial pressure gradient, moving from the high oxygen partial pressure side to the low oxygen partial pressure side. In the example shown in Figure 3A, to get the oxygen to move to the permeate side 148, the partial pressure of oxygen on the retentate side 146 is increased to the point where it equals or exceeds the partial pressure of oxygen on the permeate side 148. For example, if oxygen on the permeate side 148 is close to 100% of the volume at a pressure of the 1 atm, then the pressure on the retentate side 146 would be increased to at least 5 atm when atmospheric air is added, as atmospheric air contains approximately 21% oxygen by volume. Alternatively, the pressure on the permeate side could be reduced to levels at or below 0.2 atm using a vacuum driven process.

A sweep gas (not shown), such as steam or carbon dioxide, may be added to the permeate side 148 to dilute oxygen that crosses over from the retentate side 146. The sweep gas effectively lowers the oxygen partial pressure on the permeate side 148, which drives diffusion of oxygen from the retentate side 146. If a sweep gas is used, the percentage of oxygen within the oxygen return line 156 is much lower, as it is diluted by the sweep gas. In some examples, the oxygen percentage could drop below 10%. However, if steam is used the sweep gas, a heat exchanger can be placed downstream of oxygen separation module 114 to condense the steam to water, increasing the relative amount of oxygen in the oxygen return line 156.

If carbon dioxide is used as a sweep gas, the amount required to produce the desired oxygen level in the oxygen return line 156 can be adjusted. For example, by altering the amount of sweep gas the amount of oxygen present in the oxygen return line 156 as it leaves the oxygen separation module 114 can be controlled.

The oxygen flux across the oxygen separation membrane 206 is dependent upon the thickness of the membrane. A thin membrane allows oxygen to cross more quickly than a thick membrane. An oxygen separation membrane 206 comprised of a single layer (not considering the flameless combustion layer 204), or monolithic type membrane, can have thicknesses in the range of 0.1 to 0.2 micrometer (pm) to allow greater oxygen flux. However, these thicknesses may not be practical due to susceptibility to mechanical instability, although the flameless combustion layer 204 may provide enhanced support allowing a thinner membrane to be used. If a monolithic membrane is to be used, thicknesses below 0.2 mm are generally not used. For example, a monolithic type membrane may have a thickness of 80 pm to 300 pm, or 80 pm to 3 mm, or 750 pm 23 mm. The oxygen separation membrane may have an oxygen permeation of 10 mm/(min*cm²) and a selectivity of greater than about 10,000 for oxygen over nitrogen at temperatures of about 950°C.

Other membrane configurations that may be used as the oxygen separation membrane 206 include asymmetric membranes where a very thin oxygen-conducting layer is supported on both sides by a porous structure. This allows the use of thin membranes to allow higher oxygen flux without sacrificing stability. In this example, the flameless combustion layer 204 may be used as the porous supporting structure, either on both sides or on one side, as shown in Figures 2A and 2B.

However, the configuration of the oxygen separation membrane 206 is not limited to any of the configurations described herein, provided the oxygen flux across the membrane is sufficient. In the present disclosure the oxygen transport membrane has an oxygen flux within the range of 300 to 1500 l/hr*m², or within the range of 500 to 1300 l/hr*m², or within the range of 700 to 1000 l/hr*m².

As described with respect to Figure 2B, as the oxygen moves across the oxygen separation membrane 206 it reacts at the flameless combustion layer 204 with the fuel in the feed from the distillation top outlet 144, added from the fuel line 158, or both. This heats the oxygen separation membrane 206 to the operating temperature to allow the transport of oxygen.

During the startup of this oxygen separation module 114, the oxygen separation membrane 206 may not be hot enough for the transport of oxygen from the retentate side 146 to the permeate side 148. Accordingly, the feed from the distillation top outlet 144, the air from the air line 152, the fuel from the fuel line 158, or all of these, is heated to provide the initial heat to the oxygen transport membrane 208 to start the permeation of oxygen.

Figure 3B is a cross-section of the oxygen separation module 114 through the dotted line in Figure 3A. Like numbered items are as described with respect to Figures 1 and 2A.

Figure 4A is a front view of a flameless combustion nozzle 400. In some examples, a flame less combustion nozzle 400 is used to heat the membrane. Any number of designs may be used, so long as the designs slow the mixing of the fuel and the oxidant, allowing the recycling of exhaust gases from the reaction into the fuel/air mixture as a diluent to lower the temperature of the reaction. In the flameless combustion nozzle of Figure 4A, the oxidant gas, such as air, is introduced through a series of openings 402 in a ring around the center of the nozzle. The fuel, feed gases, or both, are introduced through a central opening 404.

Figure 4B is a perspective view of the flame less combustion nozzle 400. As can be seen in Figure 4B, the central opening 404 is raised in this example, providing further separation between the fuel and the oxidant gases released from the other openings, driving cycling flow that recycles the exhaust gases into the reaction.

Figure 5 A is a schematic drawing of an oxygen separation module 114 where a hydrocarbon fuel is provided to the retentate side 146. Like numbered items are as described with respect to Figures 1, 2A, and 4. In this example, a flameless combustion layer 204 is disposed on the retentate side 146 of the oxygen transport membrane 202, providing the configuration discussed with respect to Figure 2A. However, in some examples, the flameless combustion layer 204 is omitted, as the flameless combustion nozzle 400 may be sufficient to heat the oxygen separation membrane 206.

As shown in Figure 5A, a flameless combustion nozzle 400 is disposed at the connection of the distillation top outlet 144 to the oxygen separation module 114. The air line 152 is attached to the flame less combustion nozzle 400 to provide air flow as described with respect to Figures 4A and 4B. In this example, the permeate side 148 is separated from the retentate side 146 and the distillation top outlet 144, and, thus, the outlet gas from the oxygen return line 156 would be 100% oxygen.

The configuration of the oxygen separation membrane 114 is not limited to that shown. In some designs, the offset of the flameless combustion nozzle 400 from the oxygen transport membrane 202 is increased to increase the open space in front of the flameless combustion nozzle 400. Any number of other designs may be used, for example, as discussed with respect to Figure 5B.

Figure 5B is a schematic drawing of an oxygen separation module in which the feed and a hydrocarbon fuel can be directed to both the permeate side 148 and the retentate side 146 using a valve module 502. Like numbered items are as discussed with respect to Figures 1, 2B, and 4. In this example, the oxygen transport membrane 202 has a flameless combustion layer 204 disposed on the retentate side 146 of the oxygen separation membrane 206, giving the configuration of the oxygen transport membrane 208 shown in Figure 2B. However, the oxygen transport membrane 208 is not limited to that configuration. In some examples, the flameless combustion layer 204 is disposed on both sides of the oxygen separation membrane 206 as fuel and oxidant may be introduced to both the retentate side 146 and the permeate side 148.

In the example of Figure 5B, the feed from the distillation top outlet 144 can enter either, or both, the permeate side 148 or the retentate side 148 under the control of the valve module 502. The valve module 502 can be used to adjust the relative amount of feed entering each side. For example, 80% of the overhead stream can be introduced into the retentate side 146 and 20% to the permeate side 148, or vice versa. The amount of feed may be modified as the module during startup to change the composition of the gases, for example, increasing the amount of feed to the permeate side 148 after the oxygen separation membrane 206 reaches operating temperature, creating CO2 in the outlet gases from the oxygen return line 156, as discussed further herein. The valve module 502 that can control the flow sent to either side can include, without limitation, solenoid valves, ball valves, or a combination of a backpressure needle valve and solenoid valve.

As described, the oxygen separation membrane 206 operates at about 850°C. The heat can be provided by the combustion of the hydrocarbons present in the feed stream from the distillation top outlet 144. However, in instances where the hydrocarbons are insufficient to reach the required temperature, fuel, such as methane, is added to the oxygen separation module 114 through a fuel line 158. During startup, a heat exchanger may be used to heat the module to the required temperature, either directly or by heating the air, the feed, or both. It is preferred that when using a heat exchanger or other means for heating that heat is distributed evenly throughout the module.

As noted, during start-up of the chemical complex, the oxygen transport membrane 208 will not be at the required temperature. As a result, oxygen from the injected air cannot pass into the permeate side 148. In this instance, the feed from the distillation top outlet 144 can be directed into the retentate side 146 so that combustion on that side can contribute to increasing the temperature of the oxygen transport membrane to the point where oxygen can cross. When at steady state and the temperature of the oxygen transport membrane exceeds 850°C, the overhead stream may be directed to either side because oxygen can freely pass and permit combustion on the permeate side 148, generating heat is continuously generated.

In an example, the feed from the distillation top outlet 144 is directed to the retentate side 146 and the oxygen-enriched stream comprises at least 95% oxygen, or at least 98% oxygen, or at least 99% oxygen. In some examples, the feed from the distillation top outlet 144 may be directed into the permeate side 148. In this example, the oxygen separation membrane 206 is sufficiently hot to allow oxygen permeation, and the hydrocarbons within the feed from the distillation top outlet 144 and added fuel will combust on the permeate side 148 with the oxygen crossing the oxygen separation membrane 206.

Any unreacted oxygen and the combustion products are mixed before leaving. As a result, the oxygen is diluted and the oxygen-enriched stream contains a lower concentration of oxygen. The oxygen dilution may also be significantly increased when a sweep gas is employed, for example, below an oxygen concentration of 10%. In various examples, the feed from the distillation top outlet 144 and added fuel are directed to the permeate side 148 and the oxygen enriched stream comprises at least 20% oxygen, at least 55% oxygen, or at least 90% oxygen, with the balance comprising carbon dioxide and water, and possibly other types of inert diluent.

Figure 6 is a process flow diagram of a method 600 for heating an oxygen separation membrane. The method 600 begins at block 602 with mounting a flame less combustion unit in an oxygen separation module. At block 604, an oxygen gas and fuel are introduced proximate to the flameless combustion unit. At block 606, the oxidant gas and fuel are combusted with the flameless combustion unit to heat the oxygen separation membrane.

As described herein, the flameless combustion unit can include a flameless combustion layer disposed on the retentate side of the oxygen separation membrane. The fuel is then introduced to the retentate side of the oxygen separation membrane.

The flameless combustion unit can include a flameless combustion layer disposed on the permeate side of the oxygen separation membrane. The fuel is then introduced to the permeate side of the oxygen separation membrane.

In some examples, the flameless combustion unit includes a flameless combustion burner disposed on a line to the retentate side. In these examples, the fuel is introduced to the flameless combustion burner through the line, and the oxidant gas is introduced to the flame less combustion burner through a second line.

Embodiments

In an aspect, the chemical complex includes a fuel inlet line for introducing a combustible fuel into the overhead stream.

In an aspect, the chemical complex includes a flooded gas mixer for premixing the oxygen containing gas and the lower alkane containing gas prior to introduction into the at least one oxidative dehydrogenation reactor.

In an aspect, the flameless combustor comprises a catalytic mesh disposed on the permeate side of the oxygen transport membrane. In an aspect, the flameless combustor comprises a catalytic mesh disposed on the retentate side of the oxygen transport membrane. In an aspect, the flameless combustor comprises a catalytic mesh disposed on both the permeate side and the retentate side of the oxygen transport membrane. In an aspect, the flameless combustor comprises a flameless combustion nozzle disposed on the first inlet, wherein the air inlet is fluidically coupled to the flameless combustion nozzle. In an aspect, the flameless combustor comprises a flameless combustion nozzle disposed on the second inlet, wherein the air inlet is fluidically coupled to the flameless combustion nozzle.

In an aspect, the oxidative dehydrogenation catalyst comprises a catalyst of the formula:

Mo«V/>Tc< Nbf/Pd_tO/. where a, b, c, d, e and f are the relative atomic amounts of the elements Mo, V, Te, Nb, Pd and O, respectively; and when a = 1, b = 0.01 to 1.0, c = 0.01 to 1.0, d = 0.01 to 1.0, 0.00 < e < 0.10 and f is a number to at least satisfy the valence state of the metals in the catalyst; a catalyst of the formula:

NigA/iB/DyO , where g is a number from 0. 1 to 0.9, in many cases from 0.3 to 0.9, in other cases from 0.5 to 0.85, in some instances 0.6 to 0.8; h is a number from 0.04 to 0.9; i is a number from 0 to 0.5; j is a number from 0 to 0.5; and f is a number to at least satisfy the valence state of the catalyst; A is chosen from Ti, Ta, V, Nb, Hf, W, Y, Zn, Zr, Si and Al or mixtures thereof; B is chosen from La, Ce, Pr, Nd, Sm, Sb, Sn, Bi, Pb, Tl, In, Te, Cr, Mn, Mo, Fe, Co, Cu, Ru, Rh, Pd, Pt, Ag, Cd, Os, Ir, Au, Hg, and mixtures thereof; D is chosen from Ca, K, Mg, Li, Na, Sr, Ba, Cs, and Rb and mixtures thereof; and O is oxygen; a catalyst of the formula:

MOHEAG/O/, where E is chosen from Ba, Ca, Cr, Mn, Nb, Ta, Ti, Te, V, W and mixtures thereof; chosen from Bi, Ce, Co, Cu, Fe, K, Mg, V, Ni, P, Pb, Sb, Si, Sn, Ti, U, and mixtures thereof; a = 1; k is 0 to 2; 1 = 0 to 2, wherein the total value of 1 for Co, Ni, Fe and mixtures thereof is less than 0.5; and f is a number to at least satisfy the valence state of the metals in the catalyst; a catalyst of the formula:

V/;Mo//Nb )Tc >Mct/O/. where Me is chosen from Ta, Ti, W, Hf, Zr, Sb and mixtures thereof; m is from 0. 1 to 3; n is from 0.5 to 1.5; o is from 0.001 to 3; p is from 0.001 to 5; q is from 0 to 2; and fis a number to at least satisfy the valence state of the metals in the catalyst; a catalyst of the formula:

MoXXYZ.MO/, where X is at least one of Nb and Ta; Y is at least one of Sb and Ni; Z is at least one of Te, Ga, Pd, W, Bi and Al; M is at least one of Fe, Co, Cu, Cr, Ti, Ce, Zr, Mn, Pb, Mg, Sn, Pt, Si, La, K, Ag and In; a=1.0 (normalized); r = 0.05 to 1.0; s = 0.001 to 1.0; t = 0.001 to 1.0; u = 0.001 to 0.5; v = 0.001 to 0.3; and f is a number to at least satisfy the valence state of the metals in the catalyst; a mixed metal oxide having the empirical formula:

M06.5-7.oV30d, where d is a number to at least satisfy the valence of the metals in the catalyst; or a mixed metal oxide having the empirical formula:

MO6.25-7.25V3Od, where d is a number to at least satisfy the valence of the metals in the catalyst; or any combination thereof.

In an aspect, the flameless combustor comprises a catalytic mesh disposed on the membrane. In an aspect, the catalytic mesh comprises tungsten, steel, a temperature resistant metal, or any combinations thereof. In an aspect, the catalytic mesh comprises a ceramic. In an aspect, the ceramic comprises cerium oxide.

In an aspect, the catalytic mesh is disposed proximate to the permeate side of the oxygen transport membrane. In an aspect, the catalytic mesh is disposed proximate to the retentate side of the oxygen transport membrane. In an aspect, the catalytic mesh is disposed proximate to both the permeate side and the retentate side of the oxygen transport membrane.

In an aspect, the flameless combustor comprises a flameless combustion nozzle disposed on the first inlet, wherein the air inlet is fluidically coupled to the flameless combustion nozzle. In an aspect, the flameless combustor comprises a flameless combustion nozzle disposed on the second inlet, wherein the air inlet is fluidically coupled to the flame less combustion nozzle. Another embodiment described by examples herein provides a method for heating an oxygen separation membrane. The method includes mounting a flameless combustion unit in an oxygen separation module, introducing an oxidant gas and fuel proximate to the flameless combustion unit, and combusting the oxidant gas and fuel with the flameless combustion unit to heat the oxygen separation membrane.

In an aspect, the flameless combustion unit comprises a flameless combustion layer disposed on a retentate side of the oxygen separation membrane, and comprising introducing the fuel to the retentate side of the oxygen separation membrane.

In an aspect, the flameless combustion unit comprises a flameless combustion layer disposed on a permeate side of the oxygen separation membrane, and comprising introducing the fuel to the permeate side of the oxygen separation membrane.

In an aspect, the flameless combustion unit comprises a flameless combustion burner disposed on a line to a retentate side of the oxygen separation membrane. The method further includes introducing the fuel to the flameless combustion burner through the line, and introducing the oxidant gas to the flameless combustion burner through a second line.

Other implementations are also within the scope of the following claims.

Claims

1. A chemical complex for oxidative dehydrogenation of lower alkanes, the chemical complex comprising in cooperative arrangement:

(i) at least one oxidative dehydrogenation reactor, comprising an oxidative dehydrogenation catalyst and designed to accept, an oxygen containing gas and a lower alkane containing gas, and to produce a product stream comprising a corresponding alkene and one or more of: a. unreacted lower alkane; b. oxygen; c. inert diluent; d. carbon oxides, including carbon dioxide and carbon monoxide; e. oxygenates, including but not limited to, one or more of acetic acid, acrylic acid and maleic acid; and f. water;

(ii) a quench tower for quenching the product stream and for removing water and soluble oxygenates from the product stream;

(iii) an amine wash for removing carbon dioxide from the product stream;

(iv) a dryer for removal of water from the product stream;

(v) a distillation tower for removing C2/C2+ hydrocarbons from the product stream to produce an overhead stream enriched with Cl hydrocarbons and any other compounds lighter than C2/C2+ hydrocarbons; and

(vii) an oxygen separation module comprising: an oxygen transport membrane housed inside a sealed vessel and having a retentate side and a permeate side; a first inlet for introducing the overhead stream, combustible fuel, or both into the retentate side; a second inlet for introducing the overhead stream, combustible fuel, or both into the permeate side; an air inlet for introducing air into the retentate side; a flameless combustor to heat the oxygen transport membrane; an exhaust for discharge of oxygen depleted air, combustion products from the retentate side, or both; and an outlet for removing oxygen enriched gas and combustion products from the permeate side; wherein the components in (i) through (vii) are connected in series in the sequence described, the overhead stream from (v) is directed into the retentate side of (vii), the permeate side of (vii), or both the retentate side and the permeate side of (vii), and the oxygen enriched gas and combustion products from the permeate side of (vii) is directed back to (i).

2. The chemical complex of claim 1, comprising a fuel inlet line for introducing a combustible fuel into the overhead stream.

3. The chemical complex of claim 1, comprising a flooded gas mixer for premixing the oxygen containing gas and the lower alkane containing gas prior to introduction into the at least one oxidative dehydrogenation reactor.

4. The chemical complex of claim 1, wherein the flameless combustor comprises a catalytic mesh disposed on the permeate side of the oxygen transport membrane.

5. The chemical complex of claim 1, wherein the flameless combustor comprises a catalytic mesh disposed on the retentate side of the oxygen transport membrane.

6. The chemical complex of claim 1, wherein the flameless combustor comprises a catalytic mesh disposed on both the permeate side and the retentate side of the oxygen transport membrane.

7. The chemical complex of claim 1, wherein the flameless combustor comprises a flameless combustion nozzle disposed on the first inlet, and wherein the air inlet is fluidically coupled to the flameless combustion nozzle.

8. The chemical complex of claim 1, wherein the flameless combustor comprises a flameless combustion nozzle disposed on the second inlet, and wherein the air inlet is fluidically coupled to the flameless combustion nozzle.

9. The chemical complex of claim 1, wherein the oxidative dehydrogenation catalyst comprises: a catalyst of the formula:

MOHE/CG/G/. where E is chosen from Ba, Ca, Cr, Mn, Nb, Ta, Ti, Te, V, W and mixtures thereof; chosen from Bi, Ce, Co, Cu, Fe, K, Mg, V, Ni, P, Pb, Sb, Si, Sn, Ti, U, and mixtures thereof; a = 1; k is 0 to 2; 1 = 0 to 2, wherein the total value of 1 for Co, Ni, Fe and mixtures thereof is less than 0.5; and f is a number to at least satisfy the valence state of the metals in the catalyst; a catalyst of the formula:

V/;Mo//Nb )Tcy>Mct/O/. where Me is chosen from Ta, Ti, W, Hf, Zr, Sb and mixtures thereof; m is from 0. 1 to 3; n is from 0.5 to 1.5; o is from 0.001 to 3; p is from 0.001 to 5; q is from 0 to 2; and fis a number to at least satisfy the valence state of the metals in the catalyst; a catalyst of the formula:

10. An oxygen separation module, comprising: an oxygen transport membrane housed inside a sealed vessel and having a retentate side and a permeate side; a first inlet for introducing feed from a distillation top outlet, combustible fuel, or both into the retentate side; a second inlet for introducing feed from a distillation top outlet, combustible fuel, or both into the permeate side; an air inlet for introducing air into the retentate side; a flameless combustor to heat the oxygen transport membrane; an exhaust for discharge of oxygen depleted air, combustion products from the retentate side, or both; and an outlet for removing oxygen enriched gas and combustion products from the permeate side.

11. The oxygen separation module of claim 10, wherein the flameless combustor comprises a catalytic mesh disposed on the membrane.

12. The oxygen separation module of claim 11, wherein the catalytic mesh comprises tungsten, steel, a temperature resistant metal, or any combinations thereof.

13. The oxygen separation module of claim 11, wherein the catalytic mesh comprises a ceramic.

14. The oxygen separation module of claim 13, wherein the ceramic comprises cerium oxide.

15. The oxygen separation module of claim 11, wherein the catalytic mesh is disposed proximate to the permeate side of the oxygen transport membrane.

16. The oxygen separation module of claim 11, wherein the catalytic mesh is disposed proximate to the retentate side of the oxygen transport membrane.

17. The oxygen separation module of claim 11, wherein the catalytic mesh is disposed proximate to both the permeate side and the retentate side of the oxygen transport membrane.

18. The oxygen separation module of claim 10, wherein the flameless combustor comprises a flameless combustion nozzle disposed on the first inlet, and wherein the air inlet is fluidically coupled to the flame less combustion nozzle.

19. The oxygen separation module of claim 10, wherein the flameless combustor comprises a flameless combustion nozzle disposed on the second inlet, and wherein the air inlet is fluidically coupled to the flame less combustion nozzle.

20. A method for heating an oxygen separation membrane, comprising: mounting a flameless combustion unit in an oxygen separation module; introducing an oxidant gas and fuel proximate to the flameless combustion unit; and combusting the oxidant gas and fuel with the flameless combustion unit to heat the oxygen separation membrane.

21. The method of claim 20, wherein the flameless combustion unit comprises a flameless combustion layer disposed on a retentate side of the oxygen separation membrane, and comprising introducing the fuel to the retentate side of the oxygen separation membrane.

22. The method of claim 20, wherein the flameless combustion unit comprises a flameless combustion layer disposed on a permeate side of the oxygen separation membrane, and comprising introducing the fuel to the permeate side of the oxygen separation membrane.

23. The method of claim 20, wherein the flameless combustion unit comprises a flameless combustion burner disposed on a line to a retentate side of the oxygen separation membrane, and comprising: introducing the fuel to the flameless combustion burner through the line; and introducing the oxidant gas to the flameless combustion burner through a second line.