METHOD AND FACILITY FOR PRODUCING A TARGET COMPOUND

Abstract

Disclosed is a method for the producingtiona target compoundby oxidative coupling of methane. A starting gas mixture is provided which contains an olefin, carbon monoxide, carbon dioxide and optionally hydrogen, wherein the olefin is subjected to hydroformylation with the carbon monoxide and the hydrogen of the starting mixture 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 greater by one than the first carbon number. The carbon dioxide present in the starting mixture is removed upstream and/or downstream of the hydroformylation. The carbon dioxide is subjected to dry reforming with methane to obtain carbon monoxide, and that the carbon monoxide subjected to hydroformylation comprises at least part of the carbon monoxide obtained in the dry reforming .

Claims

1. A method for producing a target compound, the method comprising: providing a starting gas mixture comprising a paraffin, an olefin, carbon monoxide, and carbon dioxide, subjecting the olefin in at least a portion of the starting gas mixture is to a hydroformylation process to obtain an aldehyde, wherein the olefin has a carbon chain having a first carbon number and the aldehyde has a second carbon chain having a second carbon number, wherein the second carbon chain is greater by one than the first carbon number, and removing wherein the carbon dioxide present in the starting mixture at least in part in at least one of the upstream or downstream or combinations of the upstream and downstream relative to the hydroformylation process, subjecting at least part of the separated carbon dioxide to a dry reforming process with methane to obtain carbon monoxide, and using at least part of the carbon monoxide obtained in the dry reforming process in the hydroformylation process.

2. The method of claim 1, wherein a provision of the starting gas mixture comprises an oxidative coupling of a second paraffin, wherein the second paraffin comprises methane.

3. The method of claim 1, wherein the aldehyde from the hydroformylation process is the target compound, or wherein the aldehyde is further reacted to produce the target compound.

4. The method of claim 3 further comprising: hydrogenating the aldehyde to produce an alcohol having a third carbon chain having the second carbon number.

5. The method of claim 4, wherein the alcohol is dehydrated to produce a second olefin having a fourth carbon chain having the second carbon number.

6. The method of claim 1, wherein the first carbon number is two and the second carbon number is three.

7. The method of claim 2 further comprising: subjecting the methane to the oxidative coupling, wherein the methane is at least partially separated from natural gas, and transferring at least one paraffin is from the natural gas into a post-catalytic steam cracking step downstream of the oxidative coupling.

8. The method of claim 1 further comprising: obtaining the carbon momoxide abtained in the dry reforming process in a first product mixture, wherein the first product mixture comprises hydrogen.

9. The method of claim 8 further comprising: subjecting a second product mixture from the dry reforming process to a water gas shift.

10. The method of claim 9, further comprising: supplying at least one of the first product mixture from the dry reforming process or the second product mixture from the water gas shift or combinations of the first product mixture and the second product mixture to the hydroformylation process, wherein the first product mixture and the second product mixture are at least partially unseparated.

11. The method of claim 1 further comprising: subjecting at least partially the carbon monoxide and the olefin from the starting gas mixture to the hydroformylation process, wherein the carbon monoxide and olefin are without a preliminary separation from one another.

12. The method of claim 1, comprising: including a second paraffin in the starting gas mixture, passing at least part of the second paraffin through the hydroformylation method unreacted, separating the second paraffin is downstream of the hydroformylation method using the second paraffin in the provision of the starting gas mixture.

13. The method of claim 1 further comprising: compressing the starting mixture to a pressure level at which the carbon dioxide is separated off and the hydroformylation process, and carrying out the dry reforming process at a lower pressure level than the pressure level in the hydroformylation process.

14. The method of claim 1, wherein the method is carried out completely non-cryogenically downstream of the provision of the starting gas mixture and the dry reforming process.

15. A system for producing a target compound, the system configured to: provide a starting gas mixture which comprises a paraffin, an olefin, carbon monoxide and carbon dioxide, and to subject the olefin in at least a portion of the starting gas mixture to hydroformylation process; obtain an aldehyde, wherein the olefin has a first carbon chain having a first carbon number and the aldehyde has a second carbon chain having a second carbon number, and wherein the second carbon number is greater by one than the first carbon number, remove the carbon dioxide present in the starting mixture in a location selected from at least one of upstream or downstream or combinations of upstream and downstream relative to the hydroformylation process, and subject at least part of the separated carbon dioxide a dry reforming process with methane to obtain carbon monoxide, and to use at least part of the carbon monoxide obtained in the dry reforming process in the hydroformylation process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0085] FIG. 1 illustrates a method according to one embodiment of the invention in the form of a schematic flowchart.

[0086] If reference is made below to method steps, such as oxidative coupling of methane, dry reforming or hydroformylation, these are also to be understood to cover the apparatus used in each case for these method steps (in particular, for example, reactors, columns, scrubbing devices, etc.), even if this is not expressly referred to. In general, the explanations relating to the method apply to a corresponding installation in the same way in each case.

DETAILED DESCRIPTION OF THE DRAWINGS

[0087] FIG. 1 illustrates a method according to a particularly preferred embodiment of the present invention in the form of a schematic flowchart and is designated overall by 100.

[0088] Central method steps or components of the method 100 are an oxidative coupling of methane, which is designated here overall by 1, and a hydroformylation, which is designated here overall by 2. The method 100 further comprises a dry reforming, designated here overall by 3.

[0089] In the example shown, a methane stream A is supplied to the method 100. Instead of the methane stream A or in addition to this, a raw natural gas stream B can also be provided. If necessary, the raw natural gas stream B can be prepared by means of any treatment step 101. Partial streams of the methane stream A or of the raw natural gas stream are denoted by D and E. Further, in the example illustrated here, a vapor stream B1 and a carbon dioxide stream B2 are provided from an external source.

[0090] The partial stream E is fed together with a partial stream F1 of a recycle stream F (or, as explained below, optionally also together with the entire recycle stream F) into the oxidative coupling 1. In this case, mixing with oxygen, which is provided in the form of a material stream C, and optionally with steam, which is provided in the form of a material stream G, is carried out. The steam of the material stream G, as well as nitrogen of an optionally provided nitrogen stream H, serves as a diluent or moderator and in this way prevents in particular a thermal runaway in the oxidative coupling 1. Water can also make a contribution in order to ensure the catalyst stability (long-term performance) and/or to enable a moderation of the catalyst selectivity.

[0091] A reactor used in the oxidative coupling 1 can have a region for performing a post-catalytic steam cracking, as was explained at the outset. A partial stream F2 of the recycle stream F comprising ethane can optionally be fed into this region. Alternatively or additionally, it is also possible to feed a separately provided ethane stream I. A feed of propane can also be provided in principle. The ethane stream I and optionally propane and heavier components can also be separated from raw natural gas, the remainder of which is then provided as methane stream A.

[0092] Downstream of the oxidative coupling 1, an aftercooler 102 is provided downstream of which there is, in turn, a condensate separation 103. A condensate stream K formed in the condensate separation 103, which contains predominantly or exclusively water and possibly further, heavier compounds, can be fed to a device 104, in which in particular a (purified) water stream M and a residual stream N can be formed.

[0093] The product mixture of the oxidative coupling 1 freed of condensate, here generally referred to as “starting gas mixture”, is compressed in the form of a material stream L in a compressor 105 and subsequently supplied to a carbon dioxide removal, designated overall by 106, which can be carried out, for example, using corresponding scrubbing. In the embodiment shown here, a scrubbing column 106a for an amine scrubbing and the regeneration column 106b for the amine-containing scrubbing liquid loaded with carbon dioxide in the scrubbing column 106a are shown. An optional scrubbing column 106c for fine purification, for example for a caustic scrubbing, is also shown. As mentioned, the removal of carbon dioxide is generally known by corresponding scrubbing and recovery. It is therefore not explained separately. As mentioned several times, a corresponding carbon dioxide removal can also take place downstream.

[0094] A carbon dioxide stream O formed in the carbon dioxide removal 106 can, as explained further below, be fed into the dry reforming 3.

[0095] A mixture of components remaining in the form of a material stream P, after the removal of carbon dioxide in the carbon dioxide removal 106, contains predominantly ethylene, ethane and carbon monoxide. It is optionally dried in a dryer 107 and then fed to the hydroformylation 2.

[0096] In the hydroformylation 2, propanal is formed from the olefins and carbon monoxide, which together with the further components explained is carried out in the form of a material stream Q from the hydroformylation 2. Optionally, unreacted ethane and other lighter boiling compounds such as methane and carbon monoxide can be separated from the material stream Q in a separation 108, which can then be transferred to the recycle stream F. Alternatives to the separation 108 are discussed further below, however, the separation 108 is a preferred embodiment.

[0097] In one of a hydrogenation 109, the propanal can be converted to propanol. The alcohol stream is fed to a further separation 110 optionally provided as an alternative to the separation 108, where even more lighter boiling components can be separated off and transferred into the recycle stream F.

[0098] The hydrogenation 109 can be operated with hydrogen which is contained in a product stream of the dry reforming 3 and is carried along in the hydroformylation. Alternatively, the separate feeding of required hydrogen in the form of a material stream R is also possible, in particular from a separation of hydrogen in a pressure swing adsorption 111.

[0099] A product stream from the hydrogenation 109 or from the optionally provided separation 110 is fed to a dehydration 112. In said dehydration, propylene is formed from the propanol. A product stream R from the dehydration 112 is fed to a condensate separation 113 where it is freed of condensible compounds, in particular water. The water can be carried out of the process in the form of a water stream T. The water streams N and T can, optionally after a suitable work-up, also be fed again to the process for steam generation. In this way, for example, at least a part of the steam flow B1 can be provided.

[0100] 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 particular likewise unreacted ethane and lighter boiling compounds can be separated off and transferred into the recycle stream F. A product stream U formed in the separation 114 can be carried out of the process and used further process steps, for example for the production of plastics or other further compounds, as indicated here overall by 115. Corresponding methods are known per se in a variety of forms and comprise the use of the propylene from the method 100 as intermediate product or starting product in the petrochemical value chain.

[0101] Unreacted ethane and other light compounds such as methane and carbon dioxide are recycled into oxidative coupling 1 in the form of a material stream F, as mentioned several times. Optionally, a separation 117 can be provided in which the partial streams F1 and F2 can be formed. In particular, methane and ethane can be separated from one another in this way, wherein the methane in the partial stream F1 in the oxidative coupling 1 can be led to the reactor inlet and the ethane in the partial stream F2 can be led to a reactor zone used for the post-catalytic steam cracking.

[0102] A water gas shift 116 is optionally connected downstream of the dry reforming 3. A product mixture V formed in each case in the dry reforming 3 or the (optional) water gas shift 116, which predominantly or exclusively contains hydrogen and carbon monoxide, is fed (after an optional hydrogen separation in the pressure swing adsorption 111), together with the material stream P freed of carbon dioxide, from the oxidative coupling 1 to the hydroformylation 2.

Exemplary Embodiment

[0103] In the context of the present invention, a starting gas mixture was considered, as can basically be provided by means of the oxidative coupling of methane. In particular, the latter has the previously recited component fractions.

[0104] As an exemplary composition and as a basis for the following calculation example, the following composition is recited:

TABLE-US-00002 Component Mole % H.sub.2 6.00 CO 1.50 CO.sub.2 3.00 Methane 72.00 Ethylene 3.50 Ethane 1.20 Higher hydrocarbons 1.50 H.sub.2O 11.30 Total 100

[0105] For an ideal overall reaction of the integrated process proposed in accordance with one embodiment of the present invention downstream of the provision of the starting gas mixture (hydroformylation, hydrogenation and dehydration), the following gross equation is obtained:

##STR00001##

[0106] Thus, in the starting gas mixture recited above, the two required equivalents of hydrogen are almost available in this exemplary embodiment and there is only a minor additional requirement. However, only about ⅓ of the stoichiometric demand of carbon monoxide is provided, while at the same time there is a significant amount of carbon dioxide. If it is now possible to convert this amount of carbon dioxide as required into carbon monoxide and if necessary hydrogen, the stoichiometry of the gross reaction equation can be easily met.

[0107] In accordance with the invention, this can be achieved by the step of dry reforming, in which the following idealized reaction takes place:

##STR00002##

[0108] Further reactions also lead to the formation of hydrogen:

##STR00003##

##STR00004##

[0109] A fine adjustment of the ratio of hydrogen to carbon monoxide is possible if necessary in the optional downstream shift reaction (in equation V from left to right) or reversed shift reaction (in equation V from right to left):

##STR00005##

[0110] Other embodiments of the oxidative coupling can also lead in particular to a lower hydrogen content in the product gas. Accordingly, the additional provision of hydrogen by the above-mentioned reactions II to V is required. A corresponding provision can take place, for example, by means of classical reforming.

[0111] In the following, a calculation example based on the oxidative coupling is recited to document the advantages that can be achieved in accordance with the present invention, in which especially the component proportions required or advantageous for a starting gas mixture are determined.

[0112] The gross equation I recited above applies to an ideal overall reaction of the integrated process after oxidative coupling (hydroformylation, hydrogenation and dehydration).

[0113] The following explanations build on the exemplary embodiment described above and assume idealized conditions and reactions I to V in a reforming, dry reforming and water gas shift or reversed water gas shift.

[0114] The demand for carbon monoxide in the hydroformylation is 1 mol of carbon monoxide/1 mol of ethylene. The amount of ethylene in the product stream of the OCM is n.sub.OCM(C.sub.2H.sub.4). Therefore, it is usually necessary to accordingly increase the proportion of carbon monoxide n.sub.OCM(CO) already present in the product gas stream after the OCM. The required additional demand n.sub.Addition(CO) of carbon monoxide is

##STR00006##

[0115] Dry reforming provides the amounts of carbon monoxide n.sub.DryRef(CO) und hydrogen n.sub.DryRef(H.sub.2). If the additional demand for carbon monoxide is completely covered by the dry reforming, then, in accordance with equation II, the following applies:

##STR00007##

##STR00008##

[0116] In other words, within the scope of the invention, a gas is considered to be ideal which has the amounts of CO and carbon dioxide defined by equations VI and VIIa in relation to ethylene. This ratio is therefore achieved by inserting equation VIIa in equation VI assuming ideal conversions according to equation II in dry reforming and with a sufficient proportion of hydrogen as in the above exemplary embodiment.

[0117] Accordingly, the following applies to the overall composition:

##STR00009##

[0118] Moreover, if the provision of additional hydrogen n.sub.Addition(H.sub.2) is also required by reforming in accordance with equation III for the total reaction I — i.e. when the amounts n.sub.DryRef(H.sub.2) and n.sub.OCM(H.sub.2) are not sufficient — the following applies here:

##STR00010##

[0119] In accordance with the stoichiometry of equation III, carbon monoxide is again formed as a coupling product:

##STR00011##

[0120] Thus, equation VI is to be extended:

##STR00012##

[0121] Insertion of equation X in equation XI results in:

##STR00013##

[0122] Further inserting of equation IX in equation XII leads to:

##STR00014##

[0123] Insertion of equation VII in equation XIII results in equation XIV.

##STR00015##

[0124] Accordingly, the relative amount of carbon dioxide present in the product gas stream of the oxidative coupling in the idealized case is obtained from equation XIV by rearranging to equation XV:

##STR00016##

[0125] If the ratio according to the equation XV is less than 0.5, there is an excess of carbon dioxide and carbon dioxide must be removed from the process by an appropriate purging stream.

[0126] At a ratio greater than 0.5, the amount of carbon dioxide is not sufficient to cover the demand for carbon monoxide, and either an import of carbon dioxide into the dry reforming step in accordance with equation II or an increase in the proportions of hydrogen and carbon monoxide by steam reforming in accordance with equation III and optionally water gas shift in accordance with equation V is required.

[0127] As already described, the ratio between hydrogen and carbon monoxide after dry reforming can be adapted as required in particular by a water gas shift.