description

Process and plant for the production of a target compound

The present invention relates to a method for producing a target compound, in particular propylene, and a corresponding plant according to the preambles of the independent patent claims.

State of the art

The preparation of propylene (propene) is described in the specialist literature, for example in the article "Propylene" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 edition. Propylene is conventionally produced by steam cracking (Steam

cracking) of hydrocarbon feeds and conversion processes in the course of refinery processes. In the latter process, propylene will not

necessarily in the desired quantity and only as one of several

Components formed in a mixture with other compounds. Other

Processes for the production of propylene are also known, but they are not always satisfactory, for example in terms of efficiency and yield.

An increasing demand for propylene ("propylene gap") is forecast for the future, which requires the provision of corresponding selective processes. At the same time, it is important to reduce or completely prevent carbon dioxide emissions. as potential

On the other hand, large amounts of methane are available as the starting compound, which is currently only recycled to a very limited extent and is mainly burned. Significant amounts of ethane are also often present in corresponding natural gas fractions.

The present invention has as its object a process for the production of propylene which is improved in particular in view of these aspects, but also for the production of other organic target compounds, in particular of

Oxo compounds such as aldehydes and alcohols with a corresponding

Carbon backbone to provide.

Disclosure of Invention

Against this background, the present invention proposes a method

Preparation of a target compound, in particular propylene, and a corresponding system with the respective features of the independent claims.

Preferred configurations of the present invention are the subject matter of the dependent patent claims and the following description.

Basically, in addition to the above-mentioned steam cracking processes, there are a large number of different processes for converting hydrocarbons and related compounds into one another, some of which will be mentioned below as examples.

For example, the conversion of paraffins to olefins of the same chain length by oxidative dehydrogenation (ODH, also known as ODHE in the case of ethane

referred to) known. A carboxylic acid with the same chain length, ie acetic acid in ODHE, is typically also formed as a by-product in ODH. However, ethylene can also be produced by the oxidative coupling of methane (OCM).

The production of propylene from propane by dehydrogenation (PDH) is also known and is a commercially available and established process. The same applies to the production of propylene from ethylene by olefin metathesis. This process requires 2-butene as an additional starting material.

Finally, there are so-called methane-to-olefin or methane-to-propylene processes (MTO, MTP) in which synthesis gas is first produced from methane and the synthesis gas is then converted into olefins such as ethylene and propylene. Corresponding methods can be based on methane, but also based on other hydrocarbons or carbonaceous

Starting materials such as coal or biomass are operated.

Steam reforming and dry reforming as well as modifications thereof including a downstream water gas shift are available as individual technologies

Adjustment of the ratio of hydrogen to carbon monoxide is also known.

Hydroformylation represents a further technology which is used in particular for the production of oxo compounds of the type mentioned at the outset.

Propylene is typically reacted in the hydroformylation, but higher hydrocarbons, in particular hydrocarbons having six to eleven carbon atoms, can also be used. In principle, the reaction of hydrocarbons with four and five carbon atoms is also possible, but of less practical importance. Hydroformylation, in which aldehydes can initially be formed, can be followed by hydrogenation. Alcohols formed by such a hydrogenation can then be dehydrated to the respective olefins.

In Green et al., Catal. Latvia 1992, 13, 341 describes a process for the production of propanal from methane and air. In principle, low yields based on methane are recorded in the process presented. The process involves oxidative coupling of methane (OCM) and partial oxidation of methane (POX) to hydrogen and carbon monoxide, followed by hydroformylation. The target product is the propanal mentioned, which has to be isolated as such. A limitation results from the oxidative coupling of methane to ethylene, for which currently only lower conversions and limited selectivities are typically achieved.

The hydroformylation reaction in the process just mentioned is carried out over a typical catalyst at 1×15° and 1 bar in an organic solvent. The selectivity to the (undesirable) by-product ethane is in the range of about 1% to 4%, whereas the selectivity to propanal should reach more than 95%, typically more than 98%. Extensive integration of process steps or the use of the carbon dioxide formed as a by-product in large quantities, in particular in the oxidative coupling of methane, is not described further here, so that there are disadvantages compared to conventional processes. Because the process uses partial oxidation as a subsequent step for oxidative coupling, i.e. there is a sequential connection,

In US Pat. No. 6,049,011 A is a process for the hydroformylation of ethylene

described. The ethylene can be formed in particular from ethane. as

In addition to propanal, the target product can also be produced with propionic acid. Dehydration is also possible. However, this publication also does not disclose any further integration and does not disclose any meaningful use of the carbon dioxide formed.

Advantages of the Invention

Against this background, the present invention proposes a method

Preparation of a target compound, in particular propylene, in which a paraffin, in particular a linear paraffin, more particularly ethane, is subjected to an oxidative dehydrogenation with oxygen to obtain an olefin, in particular a linear olefin, more particularly ethylene.

As already mentioned at the outset, oxidative dehydrogenation is a process known in principle from the prior art. In the context of the present invention, known process concepts can be used for the oxidative dehydrogenation. For example, a method as described in Cavani et al., Catal. Today 2007, 127, 1 13. In particular, catalysts containing V, Sr, Mo, Ni, Nb, Co, Pt and/or Ce and other metals can be used in conjunction with silicate, aluminum oxide, molecular sieve, membrane and/or monolith supports. For example, within the scope of the present invention, combinations and/or oxides of corresponding metals, for example

MoVTeNb oxides and mixed oxides of Ni with Nb, Cr and V are used. Examples are in Melzer et al., Angew. Chem. 2016, 128, 9019, Gärtner et al., ChemCatChem 2013, 5, 3196, and Meiswinkel, Oxidative Dehydrogenation of Short Chain Paraffines", DGMK-Tagungbericht 2017-2, ISBN 978-3-941721-74-6, as well as various patents and patent applications of the applicant disclosed.

In addition to the specific composition of the catalysts, the specific crystal arrangement is also a key feature for achieving high selectivities at high conversions, especially in the case of the MoVTeNb catalysts mentioned. Among the known catalysts, the mixed oxide catalysts mentioned have a high selectivity and activity in the oxidative dehydrogenation of ethane to ethylene . It is generally accepted that the crystal phase M1 is responsible for the excellent catalytic performance and selectivity as it is the only phase capable of abstracting the hydrogen from the paraffin, which is the first step of the reaction.

A typical by-product of the oxidative dehydrogenation is essentially the respective carboxylic acid in all process variants, i.e. acetic acid in the case of the oxidative dehydrogenation of ethane, which may have to be separated off, but may represent another valuable product and typically in concentrations of a few percent (up to low double-digit percentage range) is present. Even

Carbon monoxide and carbon dioxide are formed in the low percentage range. A typical product mixture from the oxidative dehydrogenation of ethane has, for example, the following mixture proportions (preferred value ranges are in brackets

stated):

ethylene 25 to 75 mole percent (30 to 60 mole percent)

Ethane 25 to 70 mole percent (30 to 50 mole percent)

Acetic acid 1 to 20 mole percent (5 to 15 mole percent)

Carbon monoxide 0.5 to 10 mole percent (1 to 5 mole percent)

Carbon dioxide 0.5 to 10 mole percent (1 to 5 mole percent)

This and the following information relates to the dry portion of the product mixture, which can also contain water vapor, depending on how the process is carried out. Other components such as oxygenates, i.e. aldehydes, ketones, ethers, etc., can be present in traces, i.e. typically less than 0.5 mole percent.

be included in particular to less than 0.1 mole percent in total.

In the context of the present invention, the olefin formed in the oxidative dehydrogenation is subjected to hydroformylation with carbon monoxide and hydrogen to give an aldehyde.

Hydroformylation processes are also known in principle from the prior art. Recently come with appropriate procedures, as in the below

described in the literature cited, typically Rh-based catalysts are used. Older processes also use Co-based catalysts.

For example, homogeneous, Rh(I)-based catalysts with phosphine and/or phosphite ligands can be used. These can be monodentate or bidentate complexes. For the production of propanal, reaction temperatures of 80 to 150 Ό and corresponding are typically used

catalysts used. All methods known from the prior art can also be used within the scope of the present invention.

The hydroformylation typically operates with a 1:1 ratio of hydrogen to carbon monoxide. In principle, however, this ratio can be in the range from 0.5:1 to 10:1. The Rh-based catalysts used can have a Rh content of 0.01 to 1.00 percent by weight, the ligands in the

excess may be present. Further details are described in the article "Propanal" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 edition. The invention is not limited by the process conditions mentioned.

In another process, as described, for example, in the "Hydroformylation" chapter by Moulijn, Makee & van Diepen, Chemical Process Technology, 2012, 235, a pressure of 20 to 50 bar is used with a Rh-based catalyst and a pressure of 20 to 50 bar with a Co -based catalyst used a pressure of 70 to 200 bar. Co also appears to be relevant for hydroformylation in its metallic form. Other metals are more or less unimportant, especially Ru, Mn and Fe. The temperature range used in the process mentioned is between 370 K and 440 K.

In the process disclosed in the chapter "Synthesis involving carbon monoxide" in Weissermel & Arpe, Industrial Organic Chemistry 2003, 135, mainly Co and Rh phosphine complexes are used. With specific ligands, the hydroformylation can be carried out in aqueous medium and the catalyst can be easily recovered.

According to Navid et al., Appl. Catal. A 2014, 469, 357, everyone can in principle

Transition metals capable of forming carbonyls are used as potential hydroformulation catalysts, with activity observed according to this publication according to Rh>Co>Ir, Ru>Os>Pt>Pd>Fe>Ni.

By-products in the hydroformylation are formed in particular by the

Hydrogenation of the olefin to the corresponding paraffin, eg from ethylene to ethane, or the hydrogenation of the aldehyde to the alcohol, ie from propanal to propanol. According to the article "Propanols" in Ullmann's Encyclopedia of Industrial

Chemistry, 2012 Edition, propanal formed by hydroformylation can be used as a major source of 1-propanol in industry. In a second step, propanal can be hydrogenated to 1-propanol.

In the context of the present invention, the paraffin and the olefin have a carbon chain with a first carbon number and the aldehyde has a carbon chain with a second carbon number which is one greater than the first carbon number as a result of chain extension in hydroformylation. the

The present invention is described below primarily with reference to ethane as the paraffin and ethylene as the olefin, but can in principle also be used with higher hydrocarbons.

As mentioned, carbon dioxide is formed as a by-product in the oxidative dehydrogenation and the by-product carbon dioxide, which is contained in the above-mentioned contents in a corresponding product mixture, is subjected, according to the invention, at least in part to dry reforming with methane to obtain carbon monoxide. Since the carbon dioxide content in a corresponding product mixture is typically in the single-digit percentage range, further carbon dioxide from other sources can be fed to the dry reforming at any time in addition to the carbon dioxide from the oxidative dehydrogenation. However, the invention always includes that the carbon dioxide formed as a by-product of the oxidative dehydrogenation is fed at least in part to the dry reforming.

Dry reforming is also a fundamentally known process from the prior art. Instead of many, reference is made to Haimann, "Carbon Dioxide Reforming. Chemical fixation of carbon dioxide: methods for recycling CO 2 into useful products", CRC Press 1993, ISBN 978-0 -8493-4428-2, referenced. the

Dry reforming is also referred to as carbon dioxide reforming. In the

In dry reforming, carbon dioxide is reacted with hydrocarbons such as methane. Synthesis gas containing hydrogen and carbon monoxide as well as unreacted carbon dioxide and any hydrocarbons used is formed, as is conventionally produced by steam reforming. In the dry reforming, the educt steam is replaced by carbon dioxide to a certain extent. In dry reforming, one molecule of carbon dioxide is reacted with one molecule of methane to form two molecules of hydrogen and two molecules of carbon monoxide. A certain challenge in dry reforming is the comparatively simple further reaction of the hydrogen formed

carbon dioxide to water and carbon monoxide.

In dry reforming, pressures of up to 40 bar and temperatures of up to 950 Ό are typically used. The dry reformation will

typically performed using Ni or Co catalysts or bimetallic catalysts comprising Ni and Co. More details are

for example in the articles "Gas Production: 2. Processes" and "Hydrogen: 2.

Production" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 edition, and in the "Synthesis Gas" chapter in Weissermel & Arpe, Industrial Organic Chemistry, 2003, 15. Embodiments, in particular of the catalysts mentioned, can also be found, for example, in San-Jose -Alonso et al, Appl Catal A, 2009, 371, 54, and Schwab et al, Chem Ing Tech 2015, 87, 347.

As mentioned, in embodiments of the present invention, a

Hydrogenation and dehydration of those formed in hydroformylation

Components for the production of other products are made.

The hydrogenation of different unsaturated components is a well-known and established technology for the conversion of components with a

Double bond in the corresponding saturated compounds. Typically, very high or complete conversions with selectivities of well over 90% can be achieved. Typical catalysts for the hydrogenation of

Carbonyl compounds are based on Ni, as also for example in the article

"Hydrogenation and Dehydrogenation" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 Edition. Noble metal catalysts can also be used specifically for olefinic components. Hydrogenation is one of them

Standard reactions of technical chemistry, as well as, for example, in M. Baerns et al., "Example 1 1.6.1: Hydrogenation of double bonds", Technische Chemie 2006,

439, shown. In addition to unsaturated compounds (this refers in particular to olefins), the authors also mention other groups of substances, such as in particular aldehydes and ketones, as substrates for a hydrogenation. Low-boiling substances such as butyraldehyde from hydroformylation are hydrogenated in the gas phase. as

Here, Ni and certain noble metals such as Pt and Pd, typically in supported form, are used as hydrogenation catalysts.

For example in the article "Propanols" in Ullmann's Encyclopedia of Industrial

Chemistry, 2012 edition, describes a heterogeneous gas-phase process which is carried out at 110 to 1500 and a pressure of 0.14 to 1.0 MPa at a ratio of hydrogen to propanal of 20:1. Reduction occurs with excess hydrogen and the heat of reaction is removed by circulating the gas phases through external heat exchangers or by cooling the reactor internally. The efficiency based on hydrogen is more than 90%, the conversion of the aldehyde is up to 99.9% and there are

Alcohol yields greater than 99%. Commonly used commercial catalysts include combinations of Cu, Zn, Ni and Cr supported on alumina or kieselguhr. Dipropyl ether, ethane and propyl propionate are mentioned as typical by-products that may be produced in trace amounts. According to the general state of the art, the hydrogenation is preferably carried out in particular only with

stoichiometric amounts of hydrogen or only a small amount

excess hydrogen.

Details for corresponding liquid-phase processes are also given in the literature. These are carried out, for example, at a temperature of 95 to 12°C and a pressure of 3.5 MPa. Typically preferred as catalysts are Ni, Cu, Raney-Ni or supported Ni catalysts reinforced with Mo, Mn and Na. For example, 1-propanol can be produced with 99.9% purity. The main problem in the purification of 1-propanol is the removal of water from the product. If, as in one embodiment of the present invention, propanol is dehydrated to propylene, water is also one of the in this step

Reaction products are, so that no water must be removed in advance. The separation of propylene and water is therefore easy.

The dehydration of alcohols over suitable catalysts to produce the corresponding olefins is also known. In particular, the production of ethylene (from ethanol) is common and is gaining ground in connection with the

increasing production volumes of (bio)ethanol. The commercial application has been realized by different companies. For example, reference is made to the already mentioned article "Propanols" in Ullmann's Encyclopedia of Industrial Chemistry and Intratec Solutions, "Ethylene Production via Ethanol Dehydration", Chemical Engineering 120, 2013, 29. According to this, the dehydration of 1- or 2-propanol to propene has hitherto had no practical value. Nevertheless, the dehydration of 2-propanol is very easy to carry out in the presence of mineral acid catalysts at room temperature or above. The reaction itself is endothermic and equilibrium limited. High conversions are favored by low pressures and high temperatures. Typically, heterogeneous catalysts based on Al2 0 3 or Si0 2 used. In general, several types of acidic catalysts are suitable, and molecular sieves and zeolites, for example, can also be used. Typical temperatures are in the range of 200 to 250 O for the dehydration of ethanol or at 30 0 to 400 Ό for the

Dehydration of 2-propanol or butanol. Due to the

Equilibrium limitation, the product stream is typically separated

(Removal of the olefin product and also at least part of the water by, for example, distillation) and the stream containing the unconverted alcohol is used for

Reactor inlet recycled. In this way, a total of very high

Selectivities and yields can be achieved.

The present invention proposes a total of the coupling of the oxidative

Dehydrogenation, a downstream hydroformylation process, and dry reforming. Particular advantages result in the context of the present invention, in particular from the fact that the dry reforming can be carried out with the carbon dioxide as the starting material, which is inevitably formed as a by-product in the oxidative dehydrogenation, and that the remaining components consist of a product mixture of the oxidative dehydrogenation and components from a product mixture of the dry reforming, the latter optionally after carrying out a water gas shift, can be used in the hydroformylation without complex cryogenic separation steps. In particular, unreacted paraffins can be carried along in the hydroformylation and then be separated off more easily, or hydrogen, formed in dry reforming can be used for later hydrogenation steps. The unreacted paraffins can easily be recycled and reused in the reaction feed.

The present invention thus proposes that the carbon dioxide formed as a by-product in the oxidative dehydrogenation is at least partially subjected to dry reforming with methane to obtain carbon monoxide. Carbon monoxide and/or hydrogen are obtained in the dry reforming, preferably both, and the carbon monoxide obtained in the dry reforming and/or the hydrogen obtained in the dry reforming are in turn at least partly fed to the hydroformylation. The carbon dioxide can be removed upstream and/or downstream of the hydroformylation. In this way, within the scope of the present invention, there is a particularly advantageous and value-added use of the carbon dioxide formed in the oxidative dehydrogenation and which cannot be avoided as a by-product. The advantages of the invention therefore consist in an advantageous use of a (by-)product of one method in the other and an advantageous use of the products of both methods in a subsequent step. As mentioned, the wording that "the carbon dioxide formed as a by-product in the oxidative dehydrogenation is at least partially subjected to dry reforming with methane to obtain carbon monoxide" does not preclude the dry reforming from further, provided from any source Carbon dioxide can be supplied. This is the case in one embodiment of the present invention.

In a further embodiment of the present invention, the

Dry reforming can be carried out in an electrically heated reactor. A particular advantage of this is the avoidance of carbon dioxide emissions from the firing, which ideally reduces the carbon dioxide emissions of the

Complete process can be avoided completely.

As mentioned, a carboxylic acid in particular can be formed as a further by-product in the oxidative dehydrogenation, in particular acetic acid in the case of ethane as input in the oxidative dehydrogenation. This acetic acid, together with the water of reaction, can be produced comparatively simply by condensation

and/or a water wash can be separated from a corresponding product mixture of the oxidative dehydrogenation. Due to its high interaction with suitable solvents or washing liquids, carbon dioxide can also be removed from the product mixture comparatively easily, with known methods for removing carbon dioxide, in particular corresponding washing

(e.g. amine scrubbing) can be used. A cryogenic

Separation is not necessary, so that the entire process of the present invention, at least including the dry reforming and hydroformylation, does not require cryogenic separation steps. If subsequent steps require the absence or only a very low residual concentration of carbon dioxide (e.g. due to catalyst inhibition or poisoning), the residual carbon dioxide content after an amine wash can be further reduced by an optional caustic wash as fine cleaning, as required.

Any hydrous ones occurring within the scope of the present invention

Gas mixtures can be subjected to drying at a suitable point in each case. For example, drying can take place downstream of the hydroformylation if, in one embodiment of the present invention, this takes place in the aqueous phase and the hydrogenation downstream of the hydroformylation requires a dry stream as reaction feed. If this is not necessary for the subsequent process steps, the drying does not have to be carried out to complete dryness, but water contents can also remain in the corresponding gas mixtures, provided these are tolerable. Different drying steps can also be provided at different points in the process and possibly with different degrees of drying.

The by-products just mentioned are separated off in an advantageous manner in a completely non-cryogenic manner and are therefore extremely simple in terms of apparatus and energy consumption. This represents a significant advantage of the present invention over processes according to the prior art, which typically require complex separation of components which are undesirable in subsequent process steps.

A "non-cryogenic" separation is a separation or a separation step that is carried out, in particular, at a temperature level above 0

Ό, in particular at typical cooling water temperatures of 5 to 40Ό, in particular from 5 to 25 O, is carried out, if necessary also above the ambient temperature. In particular, a non-cryogenic separation in the sense understood here represents a separation without the use of a C2 and/or C3 cooling circuit and it therefore takes place above -30Ό, in particular above -20TT

Another by-product of the oxidative dehydrogenation typically present in a corresponding product mixture is unreacted paraffin and carbon monoxide. These compounds can be converted into the subsequent hydroformylation without problems. Carbon monoxide can be reacted with the olefin together with carbon monoxide from the dry reforming. The paraffin will

typically not converted in the hydroformylation. Since heavier compounds with a higher boiling point or a different polarity are formed in the hydroformylation, these can be separated from the remaining paraffin comparatively easily and also non-cryogenically.

In the context of the present invention, the aldehyde formed in the hydroformylation can represent the target compound, or in the context of the present invention this aldehyde can be further converted into an actually desired target compound. In particular, the latter variant represents a particularly preferred embodiment of the present invention.

In particular, when the aldehyde is converted into the target compound, the aldehyde can first be hydrogenated to form an alcohol which has a carbon chain with the second number of carbons, ie the same number of carbons as the aldehyde. A corresponding process variant is particularly advantageous because hydrogen contained in a product mixture of the dry reforming can be used for this, which is already upstream of the hydroformylation in one

Feed mixture present and can be performed by the hydroformylation. A content of hydrogen and carbon monoxide in a product mixture of

Within the scope of the present invention, dry reforming can be set in particular in a water-gas shift of a type that is known in principle. the

Water gas shift can, in particular, downstream of the dry reforming and

be carried out in particular upstream of the hydroformylation. In particular, the water gas shift takes place before a union of streams from the

dry reforming and oxidative dehydrogenation. The present invention

enables the hydrogen and/or carbon monoxide content to be precisely adjusted to the respective requirement in the hydroformylation or the downstream hydrogenation through the use of the water-gas shift.

A corresponding water-gas shift can in particular also take account of any carbon monoxide content in a product mixture of the oxidative dehydrogenation which is combined with carbon monoxide from the dry reforming for use in the hydroformylation. The use of a

Water-gas shift downstream of the dry reforming thus enables precise adaptation to the respective requirements in the hydroformylation.

Hydrogen can be fed in at any suitable point in the process according to the invention and its configurations, in particular upstream of the optionally provided hydrogenation. In this way, hydrogen is available for this hydrogenation. The feed need not take place immediately upstream of the hydrogenation; rather, hydrogen can also be provided by upstream of the

Hydrogenation present or carried out process or separation steps are fed. Hydrogen can, for example, from a partial stream of a

Product stream of the dry reforming separated or formed as a corresponding partial stream, for example by known separation steps such as pressure swing adsorption.

According to a further embodiment of the present invention, when the aldehyde is converted into the actual target compound of the process according to the invention, the alcohol formed by the hydrogenation is dehydrated to form a further olefin (based on the earlier olefin formed in the oxidative dehydrogenation), the further olefin, especially propylene, a

Carbon chain with the second carbon number mentioned, ie the carbon number of the previously formed aldehyde and the alcohol formed therefrom.

In particular, the alcohol formed in the reaction of the aldehyde can

comparatively easy to separate from unreacted paraffin. In this way, a non-cryogenic recycle stream of the paraffin can also be formed here and returned, for example, to the oxidative dehydrogenation.

As already mentioned several times, the first number of carbons can be two and the second number of carbons three in the context of the present invention, so ethylene can first be prepared as an olefin from ethane as paraffin in the oxidative dehydrogenation, with the ethylene in the hydroformylation to propanal is implemented. This propanal can then be converted into propanol by hydrogenation and this in turn can be converted into propylene by dehydration.

In a particularly preferred embodiment, the present invention allows the use of all components of natural gas. For this purpose, raw natural gas can be used and separated into a methane fraction and a fraction with heavier hydrocarbons, particularly rich in ethane. The methane fraction can

Dry reforming and the fraction with heavier hydrocarbons are fed to the oxidative dehydrogenation. The fraction with heavier

Hydrocarbons can also be treated further, for example if a substantially pure ethane fraction is to be formed for oxidative dehydrogenation.

As already mentioned, the carbon monoxide obtained in dry reforming can be obtained in a product mixture which also contains at least hydrogen. This hydrogen can be passed through the hydroformylation and then used in a hydrogenation. As already mentioned, the product mixture from the dry reforming can be subjected to a water-gas shift. In particular, the product mixture from the

Dry reforming and / or the product mixture from the water gas shift are at least partially subjected to the hydroformylation unseparated.

Other aspects of the present invention have also been mentioned in principle. In particular, the olefin obtained in the oxidative dehydrogenation can be obtained in a product mixture which also contains carbon dioxide and

Contains carbon monoxide, the carbon dioxide being separated off at a suitable point, at least in part non-cryogenically, from the product mixture of the oxidative dehydrogenation or a subsequent step and subjected to dry reforming. As mentioned, the carbon dioxide can be separated off either before or after the hydroformylation. The carbon monoxide and the olefin can be subjected to hydroformylation, at least in part, without first separating them from one another. how

mentioned, a complete non-cryogenic separation of gas mixtures obtained can in principle be achieved within the scope of the present invention. This does not necessarily apply to the aforementioned separation of natural gas into the

methane fraction and the fraction with heavier hydrocarbons.

As already mentioned, at least part of the paraffin can undergo the oxidative dehydrogenation and the hydroformylation unreacted. As mentioned in detail above, this part can be separated off downstream of the hydroformylation and recycled to the oxidative dehydrogenation. The separation can be directly downstream of the

Hydroformylation, ie before each hydroformylation subsequent

Process step, or downstream one of the hydroformylation following

Method step, for example after a hydrogenation or dehydration, but also after any separation or processing steps.

In a particularly preferred embodiment of the present invention, a product mixture from the oxidative dehydrogenation, in particular after a

Condensate separation, compressed to a pressure level at which both the

Carbon dioxide from the oxidative dehydrogenation before and/or after

Hydroformylation separated and the hydroformylation are carried out. If appropriate, additional intermediate steps can also be provided between the removal of carbon dioxide and the hydroformylation upstream and/or downstream thereof. Both procedures are essentially based on the same thing

Pressure level, which means in particular that there is no additional compression between the two and the exact operating pressure of both steps only results from the process-related pressure losses between the two steps.

The pressure level at which the removal of carbon dioxide and the hydroformylation are operated is preferably the highest pressure level in the

Overall process is, which means in particular that the dry reforming is carried out at a lower pressure level than the removal of carbon dioxide and the hydroformylation upstream and / or downstream thereof.

In this way, on a deployment of otherwise necessary

additional compression steps and corresponding compressors are dispensed with. The oxidative dehydrogenation is within the scope of the present invention

advantageously at a pressure level of 1 to 10 bar, in particular 2 to 6 bar, the dry reforming at a pressure level of advantageously 15 to 100 bar, in particular 20 to 50 bar, and the hydroformylation and the removal of carbon dioxide are advantageously carried out at a pressure level of 15 to 100 bar, in particular 20 to 50 bar.

The present invention also extends to a plant for the production of a target compound, with respect to which the corresponding independent

Patent claim is expressly referenced. A corresponding system, which is preferably set up to carry out a method as explained above in different configurations, benefits in the same way from the advantages already mentioned above.

The invention is explained in more detail below with reference to the accompanying drawing, which illustrates a preferred embodiment of the present invention.

Brief description of the drawings

FIG. 1 illustrates a method according to an embodiment of the invention in the form of a schematic flow chart.

Is followed by process steps such as the oxidative dehydrogenation, the

When dry reforming or hydroformylation is mentioned, this should also include the apparatus used for each of these process steps (in particular, e.g

Reactors, columns, washing devices, etc.) are understood, even if no express reference is made thereto. In general, the explanations relating to the procedure apply equally to a corresponding system.

Detailed description of the drawings

In FIG. 1, a method according to a particularly preferred embodiment of the present invention is illustrated in the form of a schematic flow chart and denoted overall by 100.

Central process steps or components of the process 100 are an oxidative dehydrogenation, which is denoted overall by 1 here, and a hydroformylation, which is denoted overall by 2 here. Furthermore, the method 100 includes a

Dry reforming, denoted here overall by 3.

A natural gas stream A is fed to the process 100 in the example shown.

However, instead of the natural gas stream A or in addition thereto, a separate methane stream B and an ethane stream C can also be provided. The invention is again described here with reference to ethane as the paraffin feed but, as mentioned, can also be used with higher paraffins. Furthermore, in the example illustrated here, a steam flow B1 and a carbon dioxide flow B2 are provided from an external source.

The natural gas stream is first subjected to a fractionation 101, in particular in a corresponding column, with a methane stream being obtained as the top product and a stream containing the heavier hydrocarbons of the natural gas stream, in particular ethane, being obtained as the bottom product. The top stream is denoted here by D and the bottom stream by E. The stream E, which can also contain predominantly or exclusively ethane, is fed to the oxidative dehydrogenation 1 together with a recycle stream F. In this case, mixing with oxygen, which is provided in the form of a stream G, and with steam, which is provided in the form of a stream H, is carried out. The vapor of stream H is used, as is nitrogen from an optionally provided nitrogen stream I

Diluent or moderator and in this way prevents in particular a thermal runaway in the oxidative dehydrogenation 1 . In addition, particularly in the case of the above MoVTeNb mixed metal oxide catalysts, water vapor has the function of ensuring catalyst stability

(Long-term performance), and using water vapor is a moderation of the

Catalyst selectivity possible.

An aftercooler 102 is provided downstream of the oxidative dehydrogenation, downstream of which there is in turn a condensate separator 103 . An Indian

Condensate separation 103 formed condensate stream K, which contains predominantly or exclusively water and acetic acid, an acetic acid recovery 104 can be fed, in which in particular a water stream M and a

Acetic acid stream N are formed.

The product mixture of the oxidative dehydrogenation 1 freed from condensate is compressed in the form of a stream L in a compressor 105 and then fed to a carbon dioxide removal system designated overall by 106, which can be carried out, for example, using appropriate scrubbing. In the embodiment shown here, a wash column 106a for an amine wash and the regeneration column 106b for the wash column 106a are included

Carbon dioxide laden amine-containing scrubbing liquid shown. An optional wash column 106c for fine cleaning, eg for a caustic wash, is also shown. As mentioned, the removal and recovery of carbon dioxide by appropriate scrubbing is known in principle. It is therefore not explained separately.

A carbon dioxide stream O formed in the carbon dioxide removal 106 can be conducted into the dry reforming 3, as explained further below.

A mixture of components which remains in the carbon dioxide removal facility 106 after the removal of carbon dioxide and is present in the form of a stream P contains predominantly ethylene, ethane and carbon monoxide. It is optionally dried in a dryer 107 and then fed to the hydroformylation 2 together with a further stream V (see below).

In the hydroformylation 2, propanal is formed from the olefins and carbon monoxide and hydrogen, and is carried out together with the other components explained in the form of a stream Q from the hydroformylation 2. In this case, ethane which has not reacted in particular in the oxidative dehydrogenation 1 can optionally be separated off from the stream Q in a separation 108 and can be transferred to the recycle stream F. This recycle stream F also contains other substances which may be present and which have a lower boiling point than propanal. Alternatives to partition 108 are discussed below, however, partition 108 is a preferred embodiment.

In a hydrogenation 109, the propanal can be converted to propanol. The alcohol stream is another alternative to separation 108 optional

provided separation 1 10 fed, where in particular in the oxidative

Dehydrogenation 1 unreacted ethane and any other substances present can be separated off more easily than propanol and transferred to the recycle stream F.

The hydrogenation 109 can be operated with hydrogen which is present in a product stream from the dry reforming 3 and is carried along in the hydroformylation. Alternatively, the separate feed of required hydrogen in the form of a stream R is possible, in particular from a separation of

Hydrogen in a pressure swing adsorption 1 1 1.

A product stream from the hydrogenation 109 or the optionally provided separation 110 is fed to a dehydration 112. In this, propylene is formed from the propanol. A product stream S from the dehydration 112 is fed to a condensate separator 113 and freed there of condensable compounds, in particular water. The water can be carried out in the form of a water stream T from the process. The water streams N and T can also be returned to the steam generation process, possibly after suitable treatment. In this way, for example, at least part of the steam flow B1 can be provided.

The gaseous residue remaining after the condensate separation 113 is fed to a further separation 114 optionally provided as an alternative to the separations 108 and 110, where in turn ethane which has not reacted in particular in the oxidative dehydrogenation 1 can be separated off and transferred to the recycle stream F. A product stream U formed in the separation 114 can be carried out from the process and used in further process steps, for example for the production of plastics or other further compounds, as indicated here overall by 115. A large number of corresponding processes are known per se and include the use of propylene from process 100 as an intermediate or starting product in the petrochemical value chain.

As mentioned several times, ethane which has not reacted in the oxidative dehydrogenation 1 is returned to the oxidative dehydrogenation 1 with the stream F.

The dry reforming 3 is optionally followed by a water gas shift 1 16 . A product mixture V formed in the dry reforming 3 or the (optional) water gas shift 1 16, which predominantly or exclusively contains hydrogen and carbon monoxide, is (after an optional hydrogen separation in the pressure swing adsorption 1 1 1 ) together with the stream P freed from carbon dioxide from the oxidative dehydrogenation 1 of hydroformylation 3 fed.

patent claims

1. A method (100) for producing a target compound, in which a paraffin is subjected to oxidative dehydrogenation (1) with oxygen to obtain an olefin, and in which the olefin is subjected to hydroformylation (2) with carbon monoxide and hydrogen to obtain an aldehyde , wherein the paraffin and the olefin have a carbon chain with a first carbon number and the aldehyde has a carbon chain with a second carbon number which is one greater than the first carbon number, characterized in that in the oxidative dehydrogenation (1) carbon dioxide is formed as a by-product that the carbon dioxide is at least partially subjected to dry reforming (3) with methane to obtain carbon monoxide and hydrogen,and that the carbon monoxide obtained in the dry reforming and/or the hydrogen obtained in the dry reforming is at least partly fed to the hydroformylation (2).

2. The method (100) according to claim 1, in which the aldehyde is the target compound, or in which the aldehyde is further converted to the target compound.

3. The method (100) of claim 2, wherein the aldehyde is hydrogenated to an alcohol having a carbon chain with the second carbon number.

4. The method (100) of claim 3, wherein the alcohol to an olefin

is dehydrated, which has a carbon chain with the second carbon number.

5. The method (100) according to any one of the preceding claims, wherein the first

carbon number is two and the second carbon number is three.

6. The method (100) according to any one of the preceding claims, in which the methane and the paraffin are separated from natural gas.

7. The method (100) according to any one of the preceding claims, in which the

Carbon monoxide obtained in the dry reforming (3) is obtained in a product mixture further containing at least hydrogen.

8. The method (100) according to claim 7, wherein the product mixture from the

Dry reforming (3) is subjected to a water gas shift (4).

9. Process (100) according to claim 7 or 8, in which the product mixture from the dry reforming (3) and/or the product mixture from the water-gas shift (4) are at least partly fed unseparated to the hydroformylation (2).

10. The method (100) according to any one of the preceding claims, in which the olefin obtained in the oxidative dehydrogenation (1) is obtained in a product mixture which also contains carbon dioxide and carbon monoxide, the carbon dioxide being at least partly upstream and/or or downstream of

hydroformylation (2) is separated and subjected to dry reforming (3), and wherein the carbon monoxide and the olefin are at least partly subjected to hydroformylation (2) without prior separation from each other.

1 1. The process (100) according to any one of the preceding claims, in which at least part of the paraffin passes through the oxidative dehydrogenation (1) and the hydroformylation (2) unreacted, is separated off downstream of the hydroformylation (2) and fed into the oxidative dehydrogenation (1st ) is returned.

12. The method (100) according to claim 10, wherein the product mixture from the

oxidative dehydrogenation is compressed to a pressure level at which the

Carbon dioxide is separated off and the hydroformylation (2) is carried out, and in which the dry reforming (3) is carried out at a lower pressure level.

13. The method (100) according to any one of the preceding claims, downstream of the

oxidative dehydrogenation (1) and dry reforming (3) is carried out completely non-cryogenically.

14. Plant for the production of a target compound, which has the means for it

are set up to subject a paraffin with oxygen to obtain an olefin to an oxidative dehydrogenation (1) and to subject the olefin to hydroformylation (2) with carbon monoxide and hydrogen to obtain an aldehyde

subject, wherein the paraffin and the olefin have a carbon chain with a first carbon number and the aldehyde has a carbon chain with a second carbon number that is one greater than the first

Carbon number, characterized by means arranged to form carbon dioxide as a by-product in the oxidative dehydrogenation (1), the

To subject carbon dioxide at least in part with methane to obtain carbon monoxide and hydrogen to a dry reforming (3), and in the dry reforming (3) obtained carbon monoxide and / or in the

Dry reforming (3) obtained hydrogen at least in part

To feed hydroformylation (2).

15. Plant according to claim 14, which is set up for carrying out a method according to one of the preceding claims.