EP2496537A2

EP2496537A2 - Method and device for producing alkene derivatives

Info

Publication number: EP2496537A2
Application number: EP10788103A
Authority: EP
Inventors: Christophe Claeys; Alberto Garcia; Sylvain Gerard; Nicolas Dupont; Jean-Luc Dubois; Serge Tretjak; Nabil Tlili
Original assignee: Air Liquide SA; Arkema France SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: Air Liquide SA; Arkema France SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2009-11-02
Filing date: 2010-10-27
Publication date: 2012-09-12
Also published as: RU2012122741A; IN2012DN03071A; WO2011051621A3; KR20130004562A; FR2952053A1; BR112012010345A2; FR2952053B1; WO2011051621A2; CN102712551A; US20120277464A1

Abstract

The invention relates to a method for producing a flow containing at least one alkene derivative, including the following steps: a step a) of reacting a flow containing one or more alkenes and one or more alkanes - the ratio of said alkanes to said alkenes being at least 1 by volume - with a flow containing mainly oxygen, in order to obtain at least one converted flow containing at least said alkene derivative; a step b) of separating the converted flow produced in step a) into at least said flow containing at least said alkene derivative and a residual flow containing mainly one or more hydrocarbons and one or more inert compounds; and a step c) of separating all or a portion of said residual flow by means of permeation into at least one first flow containing mainly one or more inert compounds and a second flow containing mainly one or more hydrocarbons.

Description

Method and device for producing alkenes derivatives

The invention relates to a method and a device for producing alkenes derivatives.

The processes for producing alkenes derivatives are generally fed with alkenes of very good purity, often greater than 95% by weight, in order to minimize the separation operations of the products downstream of the transformation process. This purity is most often obtained by purifying mixtures of alkanes and alkenes of lower purity, generally by distillation or liquid-liquid extraction. The corresponding purification units represent significant investment and operating costs, in particular because of the small difference in the physical properties (for example the volatility in the case of separation by distillation) of the hydrocarbons to be separated.

US-B-6667409 discloses the integration of the process for producing alkenes from alkanes into the process for producing the alkenes derivatives. It discloses an alkane / alkene separation to obtain an alkenes-enriched feedstock which is fed to the alkene derivatization unit. This prior separation is expensive in energy.

US-4532365 and FR-A-2525212 describe the dehydrogenation of an alkane to form a mixture containing the corresponding alkene, hydrogen, carbon oxides and the unreacted alkane. This mixture, supplemented with oxygen, is sent over an oxidation catalyst to produce an alkene derivative, for example acrolein. After recovery of this derivative by absorption, the gas stream leaving the absorber is recycled to the dehydrogenation stage. However, this requires the removal of oxygen from this stream, which is obtained by reacting oxygen and hydrogen on a catalyst. The oxides of carbon are absorbed by a washing solution (e.g. amines or carbonates). The separation of carbon oxides by physicochemical washing is very energy consuming during the regeneration phase and produces waste (degraded amines, carbonates) to be treated and eliminated. In addition, the separation method used in US Pat. No. 4,532,635 does not make it possible to recover incondensable compounds such as oxygen. This can no longer be recycled and is therefore lost, which has an impact on the overall cost of the process.

US 2006/004226 A1 discloses a process for producing acrolein or acrylic acid from propane. Propane is dehydrogenated by heterogeneous catalysis, the secondary components are separated and the gaseous mixture comprising propane and propene are partially oxygenated by heterogeneous catalysis to form a stream comprising the product. This is separated into one product stream, and another stream comprising unconverted propane and excess oxygen. This stream is recycled to the dehydrogenation stage without further separation.

US-B-6423875 also discloses a process for producing an acrolein or acrylic acid derivative from a feedstock comprising propane, and air, by oxy-dehydrogenation of propane to propane. air to form a mixture containing propylene. This mixture is then directed to a gas phase oxidation process to form a stream comprising the product. This is separated into a product stream, and another stream comprising unconverted propane and inerts. This stream is recycled to the oxy-dehydrogenation stage. It is previously freed by cryogenic distillation of nitrogen and all components having a boiling point below the boiling point of propylene. The distillation used is expensive and raises safety issues because the mixture to be distilled contains hydrocarbons and oxygen. In addition, the use of air as an oxidant limits the productivity of the overall process.

US-5646304 discloses an oxidation of alkenes by pure oxygen, with recirculation of unconverted compounds, i.e. hydrocarbons, after separation by a PSA, TSA or a combination of both adsorption method. These processes are semi-discontinuous, which is a source of complexity in their control. They require many valves and wear equipment requiring expensive maintenance. Regeneration of the adsorbers requires an external gas and creates effluents that must be treated. The purge of the PSA / TSA process with a low PCI (low heating value) is burned by adding a high-PCI fuel such as natural gas. There are also risks of oxygen overconcentration in the presence of hydrocarbons in the adsorbers, especially during the recompression phases. If the adsorbents are activated carbons, the risks become prohibitive in terms of safety and flammability. In addition, argon tends to accumulate in the overall process.

An object of the present invention is to overcome all or some of the disadvantages mentioned above, that is to say in particular to provide a process and a device for producing alkenes derivatives that can be fed by a load of alkenes. low purity in terms of energy consumption and productivity, without significant investments and in good safety conditions. To this end, the invention relates to a process for producing a stream comprising at least one alkene derivative comprising the following steps:

a reaction step a) of a stream comprising one or more alkenes and one or more alkanes, the ratio of said alkanes on said alkenes being at least equal to 1 in volume, with a stream comprising mainly oxygen to obtain at least one converted stream comprising at least said alkene derivative;

a step b) of separating the converted stream resulting from step a) into at least said stream comprising at least said alkene derivative and a residual stream comprising predominantly one or more hydrocarbons and one or more inert compounds; and

- A step c) of permeation separation of all or part of said residual stream in at least a first stream comprising predominantly one or more inert compounds and a second stream comprising predominantly one or more hydrocarbons.

By "predominantly" means, here as throughout this document, at least 50% by volume. Flow means a certain amount of a fluid per unit of time, the fluid can be liquid, gaseous or two-phase. The present invention relates mainly to gas phase flows. By hydrocarbons is meant alkane, alkene or a mixture comprising at least one alkane and at least one alkene.

In step a), one of the reactive streams comprises one or more alkenes and at least as many alkanes by volume, that is to say that the volume ratio of the alkanes on the alkenes is at least equal to 1. The alkenes in question may be in particular ethylene, propylene, isobutene. Alkanes are non-reactive compounds, or less reactive, in the chemical reactions involved in the conversion, and may be methane, ethane, propane, or isobutane, for example. The other components of this stream of alkenes can be compounds that are inert in these same reactions, such as nitrogen or argon. The other compounds may further include water, CO or CO ₂ . The reaction is not with air, but with a flow comprising mainly oxygen. Preferably, this stream is gaseous and comprises at least 90% oxygen by volume. As a result, much less nitrogen is introduced into the conversion unit than if air were used. The non-reactional part of the flow is referred to as "gaseous ballast". The constituents of the gaseous ballast do not participate in the chemical reactions. Their interest lies in their heat capacity (Cp), ie their ability to capture the heat released by the chemical reaction while limiting the increase in temperature. Preferably, the gaseous ballast comprises less than 10%, or even less than 5%, by volume of a gas chosen from nitrogen, argon and their mixture. The large gaseous ballast constituted by said alkanes has several advantages over a nitrogen ballast. First, it creates a better thermal ballast, because its specific heat capacity (Cp) increases strongly with temperature, which is not the case with nitrogen. In addition, it has a certain chemical inertness under the conditions of the reaction performed in step a); moreover, if it reacts in step a), the reaction products are of a nature very similar to those which would be obtained from a charge of alkanes without alkanes. Finally, it makes it easier to satisfy the constraints of composition of the mixture related to the question of flammability by moving the reaction mixture above the upper limit of flammability. Thanks to the new properties of this ballast compared to those of a ballast containing predominantly nitrogen, the feed to step a) can contain more alkenes in volume fraction, which increases the productivity of the conversion. Indeed, a larger part of the heat of reaction can be captured by the gas ballast for the same temperature within the reactor. Finally, the thermal properties of this ballast make it possible to better control the hot spots within the catalyst bed and thus to promote the selectivity of the reaction. The conversion produces at least one converted stream comprising at least said alkene derivative to be produced. The alkenes derivatives can be in particular ethylene oxide, acrolein, acrylic acid, methacrolein, methacrylic acid. The applications can generally cover all gas phase oxidation of alkenes containing 2 to 4 carbons. The other components of the converted stream generally include other compounds, such as CO, CO ₂ , water, nitrogen and / or argon, and hydrocarbons that have not, or not completely, reacted in the conversion unit. The mixture of alkanes and other stream compounds converted constitutes a thermal gas ballast having the aforementioned advantages. Step a) can be carried out in a multitubular bed or fluidized-bed reactor, or circulating fluidized bed, or plate reactor.

In step b), the conversion stream is separated into at least one stream comprising the alkenes derivative (s) that it is desired to produce and a residual stream comprising the said gaseous ballast and the inert compounds. This separation can be done by absorption of the alkenes derivatives in one or more solvents, for example water. For this step, it is possible to use, for example, an absorption column in which the flow resulting from step a) encounters a solvent introduced at the top of the column or obtained by partial condensation of the light compounds (for example water) present in the gas phase.

In step c), this residual stream, in part or in whole, is separated in a selective permeation unit into at least a first stream mainly comprising the aforementioned inert compounds and a second stream comprising predominantly hydrocarbons. This last is generally recycled to be implemented in step a) and / or is used in another unit (dehydrogenation of alkanes, hydrocarbon cracker ...) and / or is simply used as a fuel (boiler furnace) ). The permeation unit uses one or more semi-permeable membranes having the ability to retain certain compounds and on the contrary to pass others. Depending on the purities desired, it may be necessary to use several purification stages. The permeation separation is generally carried out at a pressure of the order of 10 bar (1 bar = 0.1 MPa) and at a temperature of about 50 ° C. This type of membrane separation can be done by means of hollow fiber products composed of a polymer chosen from: polyimides, cellulose-type polymers, polysulfones, polyamides, polyesters, polyethers, polyether ketones polyetherimides, polyethylenes, polyacetylenes, polyethersulfones, polysiloxanes, polyvinylidene fluorides, polybenzimidazoles, polybenzoxazoles, polyacrylonitriles, polyazoaromatics and copolymers of these polymers.

An advantage of the process according to the invention is that it can be fed with a feedstock in which the volume ratio of the alkanes on the alkenes is at least equal to 1. The compounds which are not alkenes form a gaseous ballast consisting mainly of alkanes. In general, the gaseous ballast comprises at least 30% by volume of alkanes, preferably at least 50% by volume of alkanes. This feed generally comes from an alkane / alkene fractionation column, a catalytic cracker or cracker (optionally followed by a hydrogenation of diolefins), an alkane dehydrogenation unit or the recycling of gaseous ballast. . The alkene / alkane feed is sent directly to the conversion unit to alkenes. The separation of alkanes and inert gases (eg C0 ₂ ) by permeation after the alkene derivative production unit has the advantage of being more energy efficient than the conventional separation of alkenes and alkanes upstream of the unit. conversion to obtain a charge of high purity alkenes and a stream of alkanes. In other words, the process according to the invention, using a charge of low purity alkenes and a permeation unit, makes it possible to produce alkenes derivatives and a flow rich in alkanes at a lower energy cost than a conventional method using a charge of high purity alkenes and not implementing a permeation step.

Unlike the process as described in US Pat. No. 4,532,635, the process according to the invention, which comprises a step of permeation separation, allows the recovery of most of the oxygen and the elimination of the oxides of carbon and argon, while avoiding the need for additional energy-consuming unit operation. The permeation separation of the present invention allows the inert hydrocarbons to be selectively separated at a lower operating cost than cryogenic distillation as described in US-B-6423875. Indeed, the pressure and the temperature necessary for the permeation separation are typically 10 bar (1 bar = 0.1 MPa) and 50 ° C., whereas the cryogenic distillation as described in US-B-6423875 requires a pressure higher than 50 bar and cryogenic temperatures by definition. On the other hand, the permeation separation has the advantage of being continuous, of not requiring a regeneration step (external gas consumption and production of effluents to be treated), of not presenting the risks associated with a overconcentration of oxygen by adsorption processes and finally to purge argon which is considered a thermal poison because of its low specific heat and which, if it accumulated in the process, would degrade the thermal properties of the gaseous ballast . In addition, this makes it possible to reduce the size and therefore the cost of the upstream alkene / alkane separation process (for example a fractionation column), or even to eliminate it if the process for producing alkenes derivatives is the only process. using this charge. The operating costs (energy to separate the alkanes from the alkenes) of the fractionation column are also considerably reduced. Another advantage lies in conducting an oxidation reaction in a gaseous stream rich in alkanes which constitutes a thermal ballast. This oxidation will be done ideally thanks to a flow mainly comprising oxygen (at least 50% by volume), preferably at least 90% in order to minimize the presence of nitrogen (or other inerts) and to benefit from the advantages of a thermal ballast previously mentioned.

According to particular embodiments, the invention may include one or more of the following features:

- A non-zero proportion of said second stream comprising predominantly one or more hydrocarbons is implemented in step a). This makes it possible to increase the volume fraction of ballast in the alkenes charge converted in step a). Indeed, this charge generally comes from an alkane / alkene fractionation column, a catalytic cracker or cracker (optionally followed by a hydrogenation of diolefins) or a dehydrogenation unit of alkanes. The volume ratio of the alkanes to the alkenes is then generally between 1/20 and 20. The recycling of said second stream comprising predominantly one or more hydrocarbons in this feed makes it possible to adjust upward the volume ratio of the alkanes to the alkenes. AT step a), before conversion, the ratio by volume alkanes over alkenes must be at least equal to 1.

said stream comprising one or more alkenes and one or more alkanes used in stage a) comprises from 2% to 20% of alkenes by volume. Preferably said stream comprising one or more alkenes and one or more alkanes used in step a) comprises at least 20% of alkanes.

the process also comprises a step d) prior to the reaction step a) of a stream comprising predominantly one or more alkanes with a stream comprising predominantly oxygen to obtain at least said stream comprising one or more alkenes and one or more alkanes used in step a).

- A non-zero proportion of the second stream, obtained in step c), comprising predominantly one or more hydrocarbons, is reacted in step d).

the process also comprises a step f), adjacent to and prior to step c), of catalytic oxidation of carbon monoxide, possibly present in said residual stream mainly comprising one or more hydrocarbons and one or more inert compounds, in carbon dioxide. Step f) may relate to all or part of said residual flow.

- The method further comprises a step g), adjacent and subsequent to step c), catalytic oxidation of carbon monoxide, optionally present in said second stream comprising predominantly one or more hydrocarbons, carbon dioxide. Step g) may relate to all or part of said second stream comprising predominantly one or more hydrocarbons.

said alkenes comprise mainly, and preferably are, propylene, said alkanes comprise mainly, and preferably are, propane and said alkene derivative is acrolein and / or acrylic acid.

In a particular embodiment of the invention, a non-zero fraction of the second stream from the membrane separation, comprising predominantly hydrocarbons, typically alkanes, can be implemented in step a). "Non-zero fraction" means any fraction greater than 0% and up to 100%. By "implementation", it means that the fraction of the flow in question participates in the reaction either as a reagent or as a passive compound, with a possible role of thermal or chemical ballast.

The low purity alkenes to be converted may be from a process of oxy-dehydrogenation, or oxidative dehydrogenation, or from the dehydrogenation of the corresponding alkane. This allows a partial conversion of alkane to the corresponding alkene and allows to provide the alkene conversion process a rich alkane charge. The unconverted hydrocarbons resulting from the permeation separation can be used in the dehydrogenation unit, oxidizing or not, alkanes. However, the second stream comprising predominantly hydrocarbons, rich in alkanes, will rather be sent directly to the reaction of conversion of alkenes in step a), or to other processes (cracking, oven, etc.) in order to to free from any subsequent purification after the permeation separation to avoid any contamination or parasitic reactions in the process of oxidative or non-oxidative dehydrogenation of the alkanes.

The oxidation of the CO object of steps f) and g) can also be performed in parallel with the membrane separation. The separation is the next turn. This allows, in this case, to minimize the size of the CO converter. The invention also relates to a plant for producing a stream comprising at least one alkene derivative, said plant comprising:

a unit for converting alkenes to alkenes derivatives;

a flux source comprising from 2% to 20% by volume of one or more alkenes fluidly connected to said conversion unit;

a flow source comprising mainly oxygen fluidly connected to said conversion unit;

a separator fluidly connected to an output of said conversion unit; and

a permeation separation unit fluidly connected to an outlet of said separator.

By "fluidic connection" or "fluidically connected", it means that there is connection by a system of pipes capable of transporting a flow of material. This connection system may include valves, intermediate storages, bypasses, heat exchangers, compressors, but not chemical reactors.

According to particular embodiments, the invention may include one or more of the following features: it comprises a fluid connection between an outlet of said permeation separation unit and said conversion unit or said flow source comprising mainly one or more alkenes.

it comprises a fluid connection between an outlet of said separator and an outlet of said permeation separation unit.

said flux source comprising from 2% to 20% by volume of one or more alkenes comprises a reactor:

oxy-dehydrogenation fluidly connected to a source of a stream comprising predominantly one or more alkanes and a flow source comprising predominantly oxygen; or

dehydrogenation fluidly connected to a source of a stream comprising predominantly one or more alkanes.

the installation comprises recycling means placed between an outlet of said permeation separation unit and said oxy-dehydrogenation or dehydrogenation reactor, or said source of a flow comprising predominantly one or more alkanes.

the installation comprises a catalytic conversion unit of carbon monoxide to carbon dioxide fluidly connected to said separator and to said permeation separation unit.

the installation comprises a catalytic conversion unit of carbon monoxide to carbon dioxide fluidly connected to an outlet of said permeation separation unit. The possible recycling upstream of the oxy-dehydrogenation or dehydrogenation reactor can be done in the source of alkanes or in the flow that leaves (between the source and the oxidative dehydrogenation reactor) or even directly in the reactor of oxidative dehydrogenation. Other features and advantages will appear on reading the following description, with reference to FIG. 1, which represents a schematic and partial view illustrating an exemplary device according to the invention. In Figure 1, there is shown a reactor producing low purity alkenes (2 to 98%), for example propylene and a propane ballast. It provides a filler 23 which, mixed with a recycled stream, forms a stream 1 injected into a unit 2 for producing acrylic acid by oxidation of propylene with 99% pure oxygen by volume. There comes out a flow 3 comprising acrylic acid. This stream 3 is separated in a separator 4 into a stream 5 of acrylic acid and a stream mainly comprising propane and C0 ₂ . This flow is directed partially (flow 6 to a separation unit 7 and flow 24 which by-passes the separation unit) or totally (flow 6) to a separation unit 7 by permeation. Beforehand, condensation can separate water (mainly) from other constituents (stream 27). The separation unit 7 comprises polyetherimide hollow fiber-based membranes, sufficient in number to purge the amount of C0 ₂ produced in the unit 2 and the units 21 and 22 in the stream 8. The stream 6 feeds at a high temperature. pressure (for example 10 bar) the unit 7 containing the semi-permeable membranes. The compounds present in the stream 6 will solubilize and diffuse through the polymer fibers of the unit 7 at different speeds so that preferentially the fast compounds will cross the fiber and end up in the low pressure side of the membrane, called flow of permeate and constituting the purge. The slow compounds will remain on the high pressure side and constitute the stream 9. The stream 8 comprises C0 ₂ (the main inert compound to be purged from the stream 6) and the stream 9 comprises propane. A non-zero fraction 10 is mixed with the stream 23 to form the stream 1 sent to the conversion unit 2. A non-zero fraction 11 of the stream 9 is sent to one or more user units and / or is simply used as a fuel.

The reactor 15 performs an oxy-dehydrogenation of a stream 14 comprising propane from a source 16. This oxy-dehydrogenation requires a stream 17 comprising mainly oxygen from a source 20. A non-zero fraction 18 of the stream 9 is injected into the stream 14 or directly into the oxy-dehydrogenation reactor. Stream 23 comprises propylene and propane. The assembly 15, 16, 20 is part of a source 12 supplying the stream 1.

The stream 6, prior to entering the separation unit 7 by permeation is treated in a unit 21 catalytic conversion of carbon monoxide to carbon dioxide. An alternative to this process considers the catalytic conversion of carbon monoxide to carbon dioxide in stream 9 by unit 22 and not in stream 6 by unit 21. It is not necessarily necessary to carry out this catalytic conversion. (units 21 and 22) on all flows 6 and 9. A bypass is possible, schematized by flows 25 and 26. It can also have a bypass in the form of a flow in parallel flow 24 and equipped with a CO converter. Example 1: Carbon monoxide converter (21) placed upstream of the separation unit (7)

In Table 1 are indicated the molar compositions of the main streams generated under the conditions of molar flow rate, pressure and temperature mentioned.

Table 1

Example 2 Carbon monoxide converter (21) placed downstream of the separation unit (7)

In Table 2 are indicated the molar compositions of the main streams generated under the conditions of molar flow, pressure and temperature mentioned.

Table 2

23 1 13 5 6 8 9

Acetaldehyde mol% 0.00% 0.09% 0.00% 0.00% 0.10% 0.00% 0.12%

Acrolein mol% 0.00% 0.24% 0.00% 0.00% 0.25% 0.00% 0.31%

H ₂ 0 mol% 0.00% 16.03% 0.00% 63.03% 2.43% 1, 31% 2.68%

02 mol% 0.00% 3.99% 99.50% 0.00% 5.80% 12.22% 4.39%

Argon mol% 0.00% 1, 79% 0.50% 0.00% 2.12% 2.92% 1, 95%

CO mol% 0,00% 3,79% 0,00% 0,00% 5,31% 5,33% 5,31%

C0 ₂ mol% 0.00% 18.46% 0.00% 0.00% 23.09% 67.69% 13.34%

Propane mol% 5.50% 52.91% 0.00% 0.00% 57.97% 8.73% 68.73%

Propylene mol% 94.50% 1, 50% 0.00% 0.00% 1, 74% 0.88% 1, 93%

Acetic acid mol% 0.00% 0.02% 0.00% 1, 57% 0.00% 0.00% 0.00%

Acrylic acid mol% 0.00% 0.08% 0.00% 34.30% 0.01% 0.00% 0.01%

Other mol% 0.00% 1, 10% 0.00% 1, 10% 1, 18% 0.92% 1, 24%

Molar flow / hr 32.08 174.81 53.574 78.66 47.32 8.49 36.57

Pressure bar 7,5 2,25 3,6 1 3 2 11, 5

Temperature ^< C 60 153 20 80 40 50 50

In the tables, the pressures are in absolute bars.

Claims

claims

A process for producing a stream (5) comprising at least one alkene derivative comprising the steps of:

a step a) of reacting (2) a stream (1) comprising one or more alkenes and one or more alkanes, the ratio of said alkanes on said alkenes being at least equal to 1 by volume, with a flow (13) comprising predominantly oxygen to obtain at least one converted stream (3) comprising at least said alkene derivative;

a step b) separating (4) the converted stream (3) resulting from step a) into at least said stream (5) comprising at least said alkene derivative and a residual stream (6) comprising mainly one or hydrocarbons and one or more inert compounds; and

a step c) of permeation separation (7) of all or part of said residual stream (6) into at least a first stream (8) comprising predominantly one or more inert compounds and a second stream (9) comprising mainly one or more hydrocarbons.

Process according to claim 1, characterized in that a non-zero proportion (10) of said second stream (9) comprising predominantly one or more hydrocarbons is implemented in step a).

Process according to either of Claims 1 and 2, characterized in that the said stream (1) comprising one or more alkenes and one or more alkanes used in step a) comprises from 2% to 20% of alkenes in volume.

Process according to any one of claims 1 to 3, characterized in that it further comprises a step d) prior to the reaction step a) of a stream (14) comprising predominantly one or more alkanes with a stream ( 17) comprising mainly oxygen to obtain at least said stream (1) comprising one or more alkenes and one or more alkanes used in step a).

5. Method according to claim 4, characterized in that a non-zero proportion (18) of the second stream (9), obtained in step c), comprising predominantly one or more hydrocarbons, is reacted at step d). Process according to any one of claims 1 to 5, characterized in that it further comprises:

a step f), adjacent to and prior to step c), of catalytic oxidation (21) of the carbon monoxide, possibly present in said residual stream (6) comprising predominantly one or more hydrocarbons and one or more inert compounds, carbon dioxide; and or

a step g), adjacent to and subsequent to step c), of catalytic oxidation (22) of the carbon monoxide, possibly present in said second stream (9) comprising predominantly one or more hydrocarbons, of carbon dioxide.

Process according to any one of Claims 1 to 6, characterized in that the said alkenes comprise predominantly, and preferably are, propylene, the said alkanes comprise mainly, and preferably are, propane and the said alkene derivative is acrolein and / or acrylic acid.

Plant for producing a stream (5) comprising at least one alkene derivative, said plant comprising:

- a conversion unit (2) from alkenes to alkenes derivatives;

a flux source (12) comprising from 2% to 20% by volume of one or more alkenes fluidly connected (1) to said conversion unit (2);

a flow source (19) comprising mainly oxygen fluidly connected (13) to said conversion unit (2);

a separator (4) fluidly connected to an outlet (3) of said conversion unit (2); and

- a permeation separation unit (7) fluidly connected to an outlet (6) of said separator (4).

Plant according to claim 8, characterized in that it comprises a fluid connection (10) between an outlet (9) of said permeation separation unit (7) and said conversion unit (2) or said source (12) of stream comprising predominantly one or more alkenes.

10. Installation according to claim 8 or 9, characterized in that it comprises a fluid connection (24) between an outlet of said separator (4) and an outlet (9) of said permeation separation unit (7).

11. Installation according to any one of claims 8 to 10, characterized in that said source (12) of flux comprising from 2% to 20% by volume of one or more alkenes comprises a reactor (15):

- oxy-dehydrogenation fluidically connected (14) to a source (16) of a stream comprising predominantly one or more alkanes and (17) a source (20) of flow comprising predominantly oxygen; or

- Dehydrogenation fluidically connected (14) to a source (16) of a stream comprising predominantly one or more alkanes.

12. Installation according to claim 11, characterized in that it comprises recycling means (18) placed between an outlet (9) of said permeation separation unit (7) and said reactor (15) of oxy-dehydrogenation or dehydrogenation, or said source (16) of a stream comprising predominantly one or more alkanes.

13. Installation according to any one of claims 8 to 12, characterized in that it comprises:

a unit (21) for catalytically converting carbon monoxide into carbon dioxide fluidly connected to said separator (4) and said permeation separation unit (7); and or

- A unit (22) for catalytic conversion of carbon monoxide to carbon dioxide fluidly connected to an outlet (9) of said permeation separation unit (7).