阅读说明：本技术 方法 (Method ) 是由 弗拉塞尔·罗伯特·阿奇博尔德 R·A·乔利 M·D·A·洛佩斯 大卫·基思·韦尔奇 于 2020-05-29 设计创作，主要内容包括：公开了一种用于使烯烃加氢甲酰化为醛的方法。该方法包括：在反应区中,在配体-铑催化剂的存在下用氢气和一氧化碳对一种或多种烯烃进行加氢甲酰化；从反应区回收反应器流出物,该反应器流出物包含产物醛和配体-铑催化剂；将反应器流出物和汽提气体传递到气化器,其中该汽提气体包含一氧化碳并且由再循环汽提气体料流和补充汽提气体料流形成,其中产物醛在气化器中气化到汽提气体中,从而导致包含汽提气体和产物醛的蒸气混合物以及包含配体-铑催化剂的液体混合物；回收液体混合物并且将配体-铑催化剂再循环至反应区；回收蒸气混合物,并且从蒸气混合物中分离出产物醛,以产生产物醛料流和再循环汽提气体料流；吹扫再循环汽提气体的一部分作为经吹扫的汽提气体料流；以及将经吹扫的汽提气体料流与含氢气料流合并,以产生包含氢气和一氧化碳的重整合成气料流,并且将重整合成气料流进料至反应区。(A process for the hydroformylation of olefins to aldehydes is disclosed. The method comprises the following steps: hydroformylating one or more olefins with hydrogen and carbon monoxide in the presence of a ligand-rhodium catalyst in a reaction zone; recovering a reactor effluent from the reaction zone, the reactor effluent comprising product aldehyde and ligand-rhodium catalyst; passing the reactor effluent and a stripping gas to a gasifier, wherein the stripping gas comprises carbon monoxide and is formed from a recycle stripping gas stream and a make-up stripping gas stream, wherein the product aldehyde is gasified in the gasifier to the stripping gas, resulting in a vapor mixture comprising the stripping gas and the product aldehyde and a liquid mixture comprising the ligand-rhodium catalyst; recovering the liquid mixture and recycling the ligand-rhodium catalyst to the reaction zone; recovering the vapor mixture and separating the product aldehyde from the vapor mixture to produce a product aldehyde stream and a recycle stripping gas stream; purging a portion of the recycle stripping gas as a purged stripping gas stream; and combining the purged stripping gas stream with a hydrogen-containing stream to produce a reformed syngas stream comprising hydrogen and carbon monoxide, and feeding the reformed syngas stream to the reaction zone.)

1. A process for the hydroformylation of olefins to aldehydes, the process comprising:

a. hydroformylating one or more olefins with hydrogen and carbon monoxide in the presence of a ligand-rhodium catalyst in a reaction zone;

b. recovering a reactor effluent from the reaction zone, the reactor effluent comprising product aldehyde and the ligand-rhodium catalyst;

c. passing the reactor effluent and a stripping gas to a gasifier, wherein the stripping gas comprises carbon monoxide and is formed from a recycle stripping gas stream and a make-up stripping gas stream, wherein the product aldehyde is gasified into the stripping gas in the gasifier, resulting in a vapor mixture comprising the stripping gas and the product aldehyde and a liquid mixture comprising the ligand-rhodium catalyst;

d. recovering the liquid mixture and recycling the ligand-rhodium catalyst to the reaction zone;

e. recovering the vapor mixture and separating the product aldehydes from the vapor mixture to produce a product aldehyde stream and the recycle stripping gas stream for return to step (c);

f. purging a portion of the recycled stripping gas as a purged stripping gas stream; and

g. combining the purged stripping gas stream with a hydrogen-containing stream to produce a reformed synthesis gas stream comprising hydrogen and carbon monoxide, and feeding the reformed synthesis gas stream to the reaction zone in step (a).

2. The process of claim 1, wherein the supplemental stripping gas stream is from 50 mol% to 100 mol% carbon monoxide.

3. The process of claim 1 or claim 2, wherein the reaction zone is fed with the reformed syngas stream and a fresh syngas stream.

4. The process of any preceding claim, wherein the process comprises separating a synthesis gas stream into the hydrogen-containing stream and the supplemental stripping gas stream.

5. The process of claim 4, wherein the separation of the synthesis gas stream into the hydrogen-containing stream and the supplemental stripping gas stream is performed using a membrane separation unit.

6. The process of claim 5, wherein the concentration of carbon monoxide in the supplemental stripping gas stream is at least 95 mole percent.

7. The process of any one of claims 4 to 6, wherein the molar ratio of hydrogen to carbon monoxide in the syngas stream is from 0.5 to 2.0.

8. The process of any one of claims 4 to 7, wherein the molar ratio of hydrogen to carbon monoxide in the reformed syngas stream is similar to the molar ratio of hydrogen to carbon monoxide in the syngas stream.

9. The method of any preceding claim, wherein the gasifier is operated at a temperature of 60 ℃ to 160 ℃.

10. The process of any preceding claim, wherein the gasifier is operated at a pressure of from 0.1kPa to 2000 kPa.

11. The process of any preceding claim, wherein the molar ratio of hydrogen to carbon monoxide in the reformed syngas stream is from 0.5 to 2.0.

12. The process of any preceding claim, wherein the olefin is C₂To C₁₆An olefin, and the aldehyde is C₃To C₁₇An aldehyde.

Technical Field

The present invention relates to a process for the hydroformylation of olefins to produce aldehydes. In particular, but not exclusively, the invention relates to a method for making C₈Hydroformylation of olefins to produce C₉A method for producing an aldehyde. The invention also relates to a process for hydroformylating an olefin to produce an aldehyde using a ligand-rhodium catalyst.

Background

Hydroformylation of olefins to produce aldehydes is carried out industrially on a large scale. Aldehydes are typically intermediates in the production of alcohols, acids or esters. A well known process for producing such products is the low pressure Oxo (LP Oxo) process supplied by Dow and Johnson Matthey Davy. In a typical scheme, for example, as described in US4148830 or US5087763, hydroformylation is carried out in the liquid phase using a ligand-rhodium catalyst. The liquid phase reactor effluent exits the hydroformylation reactor and is fed to a catalyst separation unit where the liquid catalyst solution is separated from the product aldehyde. The liquid catalyst solution is then returned to the reactor. The liquid catalyst solution typically comprises a solvent, rhodium, ligand and other components present in the reactor.

Many variants of molecules that can be used as ligands are known. Commercially used ligands are typically phosphines, such as triphenylphosphine; monophosphites, such as trimethylolpropane phosphite or tris (2, 4-di-tert-butylphenyl) phosphite; a bisphosphite; or a mixture of any of these. WO2016089602 lists various ligands. Of these 3 types of ligands, monophosphites are considered the most active, but are also considered the weakest interacting ligands with rhodium, which is believed to result in less stable catalyst complexes.

A typical catalyst separation unit includes a gasifier in which a portion of the reactor effluent is gasified. This results in a gas phase containing aldehyde product and essentially no catalyst and a liquid phase containing liquid catalyst solution. The gas phase is transferred for further processing. Further processing typically includes an aldehyde purification stage in which unconverted olefins and paraffins are removed along with dissolved syngas and other light components. The aldehydes thus produced are often used as intermediates for other products such as alcohols, acids or esters, which can often be used as plasticizers.

The gasification of aldehydes in the reactor effluent in the catalyst separation unit is assisted by the lower pressure and higher temperature in the gasifier. However, liquid catalyst solutions are often susceptible to various forms of degradation, resulting in loss of activity and loss of rhodium. Rhodium is a valuable precious metal and therefore it is desirable that the consumption of rhodium is as low as possible in order to maintain an economical process. This generally determines the maximum allowable temperature in the gasifier. Evaporation can still be increased by operating the gasifier at low pressure. Lower total pressure means lower partial pressure of aldehyde, which increases evaporation of aldehyde and is particularly useful for relatively heavier aldehydes. However, a lower total pressure (in particular vacuum) leads to a larger volume of the apparatus and thus to a more expensive apparatus. At sub-atmospheric pressures, there is also a risk of air entering the interior of the process. This may lead to oxidation of the aldehyde and/or ligand, both of which result in increased costs.

It is therefore desirable to stabilize the catalyst to prevent losses and to allow the use of higher temperatures and pressures above atmospheric pressure.

US6500991 aims at stabilizing the catalyst by cooling the catalyst solution obtained from the gasifier and adding carbon monoxide containing gas to the liquid, or by adding carbon monoxide to the flash vessel before catalyst separation.

EP2297077 describes the use of a recycle stripping gas in order to reduce the partial pressure of aldehydes, but maintain an overall positive pressure. In the catalyst separation unit, the reactor effluent is fed to the gasifier together with a stripping gas and both are passed through the gasifier in co-current. The stripping gas is substantially free of aldehydes and therefore reduces the partial pressure of aldehydes in the gasifier, thereby increasing the driving force for the evaporation of aldehydes from the reactor effluent. The vaporizer may also be heated to further facilitate vaporization. The resulting vapor mixture comprising aldehyde and stripping gas is then separated from the remaining liquid catalyst solution. The liquid catalyst solution was returned to the reactor and the vapor mixture was fed to a condenser. In the condenser, the temperature of the vapor mixture is reduced, with the result that substantially all of the aldehyde is condensed and separated from the remaining vapor. The remaining vapor is then recompressed to the gasifier inlet pressure and reused as stripping gas.

WO2016089602 describes the addition of carbon monoxide to the gasifier stripping gas in order to reduce catalyst losses. It also suggests that lower hydrogen partial pressures in the stripping gas can contribute to lower catalyst losses. Carbon monoxide may be obtained by separating the synthesis gas into a hydrogen-containing stream and a supplemental stripping gas stream.

It is believed that the addition of carbon monoxide to the gasifier stripping gas results in a higher concentration of carbon monoxide in the liquid catalyst solution and this helps stabilize the catalyst. However, sufficiently pure carbon monoxide is rarely available in petrochemical plants, and therefore the use of syngas to produce carbon monoxide is required. There remains a need for a method of providing carbon monoxide rich gas to a gasifier while minimizing the need for additional syngas feedstock.

The present invention seeks to ameliorate some of the problems of the prior art. In particular, but not exclusively, the present invention seeks to provide an improved more cost effective process for the hydroformylation of olefins to aldehydes.

Disclosure of Invention

According to a first aspect of the present invention, there is provided a process for the hydroformylation of olefins to aldehydes, the process comprising:

a. hydroformylating one or more olefins with hydrogen and carbon monoxide in the presence of a ligand-rhodium catalyst in a reaction zone;

b. recovering a reactor effluent from the reaction zone, the reactor effluent comprising product aldehyde and the ligand-rhodium catalyst;

c. passing the reactor effluent and a stripping gas to a gasifier, wherein the stripping gas comprises carbon monoxide and is formed from a recycle stripping gas stream and a make-up stripping gas stream, wherein the product aldehyde is gasified into the stripping gas in the gasifier, resulting in a vapor mixture comprising the stripping gas and the product aldehyde and a liquid mixture comprising the ligand-rhodium catalyst;

d. recovering the liquid mixture and recycling the ligand-rhodium catalyst to the reaction zone;

e. recovering the vapor mixture and separating the product aldehydes from the vapor mixture to produce a product aldehyde stream and the recycle stripping gas stream for return to step (c);

f. purging a portion of the recycle stripping gas stream as a purged stripping gas stream; and

g. combining the purged stripping gas stream with a hydrogen-containing stream to produce a reformed synthesis gas stream comprising hydrogen and carbon monoxide, and feeding the reformed synthesis gas stream to the reaction zone in step (a).

The present invention therefore relates to a catalyst separation unit for separating a ligand-rhodium catalyst from an effluent of a hydroformylation reaction zone, wherein a recycle stripping gas is used in a gasifier for separating product aldehydes from the ligand-rhodium catalyst, wherein the recycle stripping gas is purged, for example to prevent the accumulation of hydrogen and other inert components, wherein make-up carbon monoxide-rich gas, typically from a synthesis gas separation unit, is added to the recycle stripping gas. The purged stripping gas, still rich in carbon monoxide, is combined with a hydrogen-containing stream, typically also from a syngas separation unit, to form a reformed syngas stream which is fed to the reaction zone. Thus, the carbon monoxide contained in the make-up stripping gas stream used to generate the recycle stripping gas is not wasted and the overall demand of syngas as a source of carbon monoxide is not significantly increased as compared to processes that do not use the recycle stripping gas. Thus, the present invention achieves the advantages of reduced ligand-rhodium catalyst loss associated with a carbon monoxide rich environment in a gasifier while avoiding the disadvantages of the additional syngas feedstock requirements.

The supplemental stripping gas stream comprises carbon monoxide and is preferably enriched in carbon monoxide. Preferably, the supplemental stripping gas stream is from 50 mol% to 100 mol% carbon monoxide, more preferably the supplemental stripping gas stream is from 70 mol% to 100 mol% carbon monoxide, still more preferably the supplemental stripping gas stream is from 80 mol% to 100 mol% carbon monoxide, most preferably the supplemental stripping gas stream is from 95 mol% to 100 mol% carbon monoxide. Higher concentrations of carbon monoxide are advantageous because they allow higher concentrations of carbon monoxide in the stripping gas. Preferably, the hydrogen-containing stream is from 50 mole% to 100 mole% hydrogen, more preferably the hydrogen-containing stream is from 70 mole% to 100 mole% hydrogen, still more preferably the hydrogen-containing stream is from 80 mole% to 100 mole% hydrogen, most preferably the hydrogen-containing stream is from 95 mole% to 100 mole% hydrogen. In some embodiments, the partial pressure of carbon monoxide in the vapor mixture exiting the gasifier may be at least 15psi (103kPa) and preferably at least 20psi (138 kPa). For example, the partial pressure of carbon monoxide in the vapor mixture exiting the gasifier may range from at least 15psi (103kPa) to no more than 50psi (345 kPa). The partial pressure of hydrogen in the vapor mixture exiting the gasifier may, for example, not exceed 10psi (69kPa) and preferably not exceed 5psi (34 kPa).

Preferably, the process comprises separating a synthesis gas stream comprising carbon monoxide and hydrogen into a hydrogen-containing stream and a supplemental stripping gas stream. Thus, in practice, a syngas stream is fed to the reaction zone, wherein the carbon monoxide in the syngas stream is fed via the stripping gas in the gasifier. This may be the only synthesis gas supplied to the reaction zone; in other words, the reformed syngas stream can be the only syngas supplied to the reaction zone. Optionally, however, the reaction zone may be fed with a reformed syngas stream and a fresh syngas stream. In such embodiments, for example, the syngas feed can reach the boundary of the unit zone of the process, and a portion of the syngas feed can be separated into a make-up stripping gas stream and a hydrogen-containing stream, and a portion of the syngas feed can be fed to the reaction zone. In such cases, some of the syngas feed effectively bypasses the catalyst separation unit. Such an arrangement may be advantageous to balance the need for syngas to be fed to the reaction zone with carbon monoxide to be fed to the stripping gas. However, in such embodiments, the benefits of the present invention are still realized because the carbon monoxide in the stripping gas is still not wasted and is still fed to the reaction zone as a reformed syngas stream. In such embodiments, the molar ratio of the portion of the synthesis gas feed that is separated into the make-up stripping gas stream and the hydrogen-containing stream to the portion of the synthesis gas feed that is fed to the reaction zone as a fresh synthesis gas stream may preferably be from 0.01 to 1. More preferably the molar ratio is from 0.1 to 0.5, and most preferably the molar ratio is from 0.1 to 0.3. The molar ratio may be selected based on the separation efficiency (e.g., membrane separation efficiency if a membrane is used for separation) and the desired carbon monoxide partial pressure in the stripping gas. For example, if the supplemental stripping gas stream contains a relatively high level of hydrogen, a higher flow rate of the supplemental stripping gas stream can be used, and the flow rate of the purged stripping gas stream is correspondingly higher.

The molar ratio of carbon monoxide fed to the reaction zone to olefin fed to the reaction zone is preferably about 1. In practice, not all olefins are convertible, and carbon monoxide is only consumed for conversion of the convertible olefins. Thus, the molar ratio can be less than 1 while still providing sufficient carbon monoxide to convert all of the convertible olefins. However, for operational reasons and to enable high conversion of more valuable olefin feedstocks, a molar excess of carbon monoxide, and hence a molar ratio of greater than 1, may be desired. The molar ratio may preferably be 0.1 to 10, and more preferably 1 to 2.

The separation of the synthesis gas stream into the hydrogen-containing stream and the supplemental stripping gas stream is preferably carried out using a membrane separation unit. Such membrane separation units are commercially available from companies such as MTR and air products. The membrane separation unit is capable of achieving very high (such as at least 95 mole percent or preferably at least 99 mole percent) concentrations of carbon monoxide in the make-up stripping gas stream in an economical manner. However, such high purity may require a high flow of syngas into the membrane separation unit, and it is therefore important not to waste carbon monoxide. This is achieved in the present invention by recombining the purged stripping gas stream with a hydrogen-rich stream to produce a reformed syngas stream that is passed to the reaction zone. Alternatively or in addition, The separation of The synthesis gas stream into a hydrogen-containing stream and a supplemental stripping gas stream may be carried out using a COSORB process or a variation thereof, such as described, for example, in The adsorption of carbon monoxide in COSORB solutions: adsorption rate and capacity J.A. Hogendorn, W.P.M.van Swaaij, G.F.Versteeg, The chem.Eng.Journ.59(1995)243-252 or US4950462 or US 5382417. Alternatively or additionally, the separation of the synthesis gas stream into the hydrogen-containing stream and the supplemental stripping gas stream may be performed using cryogenic absorption of liquid nitrogen.

Preferably, the gasifier is operated at a temperature of 60 ℃ to 160 ℃, more preferably 100 ℃ to 130 ℃. Such temperatures may help drive the gasification of the product aldehydes in the gasifier. Because the process of the present invention involves a higher carbon monoxide partial pressure in the gasifier, the ligand-rhodium catalyst can be stabilized even at such temperatures and losses prevented.

Preferably, the gasifier operates at a pressure of from 0.1kPa to 2000kPa, more preferably from 100kPa to 2000kPa and most preferably from 100kPa to 300 kPa. Higher than atmospheric pressure is particularly preferred because expensive equipment for creating a vacuum is not required and the risk of air entering the gasifier is reduced.

The molar ratio of hydrogen to carbon monoxide in the synthesis gas stream is preferably in the range of from 0.5 to 2.0. The most desirable ratio of hydrogen to carbon monoxide may depend on the desired hydrogen and carbon monoxide partial pressures in the reaction zone. Preferably, the molar ratio of hydrogen to carbon monoxide in the reformed syngas stream is similar to the molar ratio of hydrogen to carbon monoxide in the syngas stream, e.g., within 10% of the molar ratio of hydrogen to carbon monoxide in the syngas stream. It is possible that the molar ratio of hydrogen to carbon monoxide in the reformed synthesis gas stream is preferably in the range of 0.5 to 2.0. The hydrogen and carbon monoxide partial pressures in the reaction zone can affect the hydroformylation reaction, rate and selectivity. Controlling the partial pressures of carbon monoxide and hydrogen in the reaction zone may advantageously be simpler if the molar ratio of hydrogen to carbon monoxide in the reformed synthesis gas stream is similar to the molar ratio of hydrogen to carbon monoxide in the synthesis gas stream.

The gasifier is preferably a falling film gasifier, but may be other types of gasifiers, including for example, vessels containing structured or random packing. The stripping gas may be fed to the gasifier either co-currently or counter-currently with the reactor effluent.

Since the recycle stripping gas is at a lower pressure than the stripping gas due to pressure drop in the process, a compressor is preferably provided to compress the recycle stripping gas before it is combined with the make-up stripping gas. A compressor is also preferably provided to compress the reformed synthesis gas stream prior to feeding it to the reaction zone. Preferably, after compressing the recycle stripping gas, the purged stripping gas stream is purged from the recycle stripping gas. In this manner, the purged stripping gas stream can be at a pressure suitable for combination with the hydrogen-containing stream to form a reformed syngas stream, which can then be compressed prior to feeding to the reaction zone, and separate compressors on the recycled stripping gas and the purged stripping gas stream are avoided.

Typically, the reaction zone is operated at about 20 bar (2MPa), for example 15 to 25 bar (1.5 to 2.5MPa), and the gasifier is operated at about 1.5 bar (150kPa), for example 1 to 2 bar (100 to 200 kPa). However, pressures of 50 to 235 bar (5 to 23.5MPa) are also known for operating the reaction zone.

Preferably, the olefin is C₂To C₁₆Olefin, more preferably C₄To C₁₂Olefins and most preferably C₈An olefin. The olefin is preferably a mono-olefin. The olefin is preferably an acyclic olefin, such as a linear or branched olefin. For example, the olefin may be propylene or n-butene. However, the olefin is preferably C₈Olefins, such as octene, dibutene, or oligoethylene. Preferably, the aldehyde is one carbon more than the olefin. Thus, the aldehyde is preferably C₃To C₁₇Aldehydes, more preferably C₅To C₁₃Aldehydes and most preferably C₉An aldehyde. The skilled person will appreciate that the aldehyde produced depends on the olefin used.

The present invention may be used with any suitable ligand system that benefits from a carbon monoxide rich stripping gas. Preferably, the ligand is a phosphine, such as triphenylphosphine; monophosphites, such as trimethylolpropane phosphite or tris (2, 4-di-tert-butylphenyl) phosphite; a bisphosphite; or a mixture of any of these.

In addition to the product aldehyde and the ligand-rhodium catalyst, the reactor effluent will typically contain additional components. Such additional components may include olefins and paraffins, ligand decomposition products, ligand stabilizers, aldehyde oligomers (sometimes referred to as "heavy components"), water, and dissolved gases. The vapor mixture exiting the gasifier will typically contain additional components in addition to the product aldehydes and stripping gas. Such additional components may include olefins, paraffins, and other light components. The olefins and paraffins will typically be condensed in the condenser while the light components will remain in the recycled stripping gas, with their levels controlled by the purging of the purged stripping gas stream.

The product aldehyde stream is preferably a liquid product aldehyde stream.

The reaction zone is understood to describe one or more hydroformylation reactors. Typically, the reaction zone will comprise one, two or three reactors. The reactors may for example be connected in series. Feed streams, such as a fresh syngas stream and a reformed syngas stream, can be provided to one or more reactors, and reactor effluent can be collected from the one or more reactors, which is passed to a gasifier.

Where a component such as product aldehyde is said to be vaporized (such as into a stripping gas), it is understood that a substantial portion of the component is so vaporized. A small portion of the components may remain in the liquid phase, for example, in equilibrium with vaporized components in the gas phase. It is possible that at least 50 mole%, preferably at least 60 mole% and more preferably at least 70 mole% of the components are so vaporized. It is possible that substantially all of the components are so vaporized. Similarly, where it is said that a component such as a product aldehyde is separated, such as from a vapor mixture, it is understood that a majority of the component is so separated. A small portion of the components may be retained. It is possible that at least 75 mole%, preferably at least 90 mole% and more preferably at least 95 mole% of the components are so separated. It is possible that substantially all of the components are so separated.

Drawings

Embodiments of the present invention will now be described, by way of example and not in any limitative way, with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of a process embodying the present invention; and is

FIG. 2 is a process flow diagram of a portion of the process of FIG. 1 embodying the present invention.

Detailed Description

In fig. 1, an olefin feed 1 is fed to a hydroformylation reaction zone 100. The reaction zone 100 comprises at least one reactor, and possibly two or three reactors, from which the reactor effluent 11 passes to a catalyst separation unit 101. The liquid ligand-rhodium catalyst solution 12 (where the solvent typically comprises heavy components, such as dimers or trimers) is recycled from the catalyst separation unit 101 to the reaction zone 100. The product aldehyde stream 13 is recovered from the catalyst separation unit 101 and passed to an aldehyde purification unit 102 from which purified aldehyde 15 is recovered. Olefins and paraffins 14 are also recovered from the aldehyde purification unit 102.

The synthesis gas feed 2 is split into a fresh synthesis gas stream 4 and a synthesis gas stream 3, the fresh synthesis gas stream 4 being fed directly to the reaction zone 100 as part of a mixed synthesis gas feed stream 10, the synthesis gas stream 3 being fed to the membrane separation unit 200. In the membrane separation unit 200, the synthesis gas stream 3 is separated into a make-up stripping gas stream 5 and a hydrogen-containing stream 6, the make-up stripping gas stream 5 is passed to the catalyst separation unit 101, the hydrogen-containing stream 6 is combined with the purged stripping gas stream 7 to form a reformed synthesis gas stream 8, the reformed synthesis gas stream 8 is compressed in a compressor 201 and fed 9 to the reaction zone 100 as part of the mixed synthesis gas feed stream 10. For operational reasons, purging from one or more of streams 6, 7, 8 or 9 may be included, for example, but is preferably avoided to avoid loss of reformed syngas.

More details of the catalyst separation unit 101 are shown in fig. 2. In fig. 2, reactor effluent 11 and optionally a small flow of nitrogen 20 to aid in hydrogen stripping are fed to flash vessel 207. The flash vessel 207 has a vent 21 to a condenser 208. The condenser 208 has a vent gas 22 and a liquid outlet stream 23, the liquid outlet stream 23 being returned to the flash vessel 207. The flash vessel 207 and condenser 208 operate to remove dissolved syngas, particularly dissolved hydrogen, from the liquid reactor effluent 11. The liquid outlet 24 of the flash vessel 207 is fed to the top of the falling film gasifier 202 together with a stripping gas 28 comprising a recycled stripping gas 27 and a carbon monoxide rich stream 5. The supplemental stripping gas stream 5 is generated by feeding the synthesis gas stream 3 to a membrane separator 200 to produce a supplemental stripping gas stream 5 and a hydrogen-containing gas stream 6. The outlet 25 of the gasifier 202 is fed to a gas/liquid separation vessel 203, from which gas/liquid separation vessel 203 the liquid ligand-rhodium catalyst solution 12 is recovered and recycled to the reaction zone 100. The vapor mixture 26 from the gas/liquid separation vessel 203 is fed to a condenser 204 and then to a further gas/liquid separation vessel 205. A product aldehyde stream 13 is recovered from the bottom of the additional gas/liquid separation vessel 205 and a recycle stripping gas 27 is recovered from the top. The recycle stripping gas 27 is compressed in recycle compressor 206 and then fed back to the falling film gasifier 202 as part of the stripping gas 28. After passing through recycle compressor 206, the purged stripping gas stream 7 is purged from recycle gas stream 27 and combined with hydrogen containing stream 6 to form reformed syngas stream 8. Reformed syngas stream 8 is compressed in syngas compressor 201 and fed 9 to reaction zone 100. Fig. 2 depicts a falling film gasifier 202, but other types of gasifiers are equally suitable.

The following examples were generated using the commercially available simulation package SimSci ProII v 9.3. The use of simulations to evaluate new methods is well established in the field of chemical engineering.

Example 1

In the process of fig. 2, a reactor effluent 11 of 333 kmol/hour at 20 bar (2MPa) and 85 ℃ is fed to a flash vessel 207 operating at 10 bar (1MPa) where most of the dissolved synthesis gas components will flash off. The reactor effluent 11 mainly comprises dissolved synthesis gas, C₈Olefin, C₈Alkane, C₉Aldehyde and catalyst solution. A small flow of 1kmol/h nitrogen 20 is also fed to the flash vessel 207 to aid in the removal of dissolved hydrogen. The vent gas 21 from the flash vessel 207 is fed to a condenser 208 to recover heavier C₈And C₉And (4) components. The liquid outlet stream 23 from the condenser 208 is returned to the flash vessel 207. The liquid outlet 24 from the flash vessel 207 is fed to the top of the falling film gasifier 202 operating at 1.5 bar (0.15 MPa). Also, stripping gas 28 is fed to the top of the falling film gasifier 202. The liquid reactor effluent and stripping gas are passed cocurrently through the falling film gasifier 202. Heating the falling film gasifier 202 to vaporize a substantial portion of the C₈And C₉And (4) components. The outlet 25 of the falling film gasifier 202 feeds a gas/liquid separation vessel 203. The liquid collected in the gas/liquid separation vessel 203 comprises the liquid ligand-rhodium catalyst solution 12 and a small portion of C₈And C₉And (4) components. The vapor mixture 26 from the gas/liquid separation vessel 203 is fed to a condenser 204 where most of the C is fed to the condenser₈And C₉The components condense and are subsequently separated from the remaining gas phase in a further gas/liquid separation vessel 205. Removing the thus obtained C-containing gas from the further gas/liquid separation vessel 205₉Aldehyde, olefin and paraffin liquid, and producingThe aldehyde stream 13 is diverted for further processing. The vent gas from the additional gas/liquid separation vessel 205 is recycle stripping gas 27, which is fed to recycle compressor 206. Recycle compressor 206 is used to overcome the small pressure drop in the stripping gas cycle. The purged recycle gas stream 7 exits from the recycle stripping gas 27 so as to maintain a constant flow in the stripping gas loop. A make-up stream provided by make-up stripping gas stream 5 is added to produce stripping gas 28.

A synthesis gas stream 3 having a flow of 100kmol/h synthesis gas at 30 bar (3MPa) is fed to the membrane separator 200, the synthesis gas stream having 2 mol% methane and a residual hydrogen and carbon monoxide molar ratio of 1/1. The membrane separator 200 produces a hydrogen containing stream 6 as a permeate stream at a flow rate of 45.6kmol/h and a supplemental stripping gas stream 5 as a retentate stream. Hydrogen-containing stream 6 comprises 96.77 mole percent hydrogen, while supplemental stripping gas stream 5 comprises 87.3 mole percent carbon monoxide. After purging the purged stripping gas stream 7 and before introducing the make-up stripping gas stream 5 as make-up, the stripping gas recycle flow is controlled to a constant flow of 2050 kmol/h. With the condenser 204 cooled to 40 ℃, the resulting carbon monoxide partial pressure in the stripping gas 28 was 17.5psi (120kPa) and the hydrogen partial pressure was 2.2psi (15 kPa). The ratio of hydrogen to carbon monoxide in the reformed syngas 8 was 0.99 mol/mol.

Example 2

According to example 1, however, the flow of synthesis gas stream 3 is reduced to 50 kmol/h. The resulting partial pressure of carbon monoxide in the stripping gas 28 is now 17.0psi (117kPa) and the partial pressure of hydrogen is 2.5psi (17 kPa). The ratio of hydrogen to carbon monoxide in the reformed syngas 8 was 0.97 mol/mol.

Example 3

According to example 1, however, the flow of synthesis gas stream 3 was reduced to 20 kmol/h. The resulting partial pressure of carbon monoxide in the stripping gas 28 is now 16.1psi (111kPa) and the partial pressure of hydrogen is 3.2psi (22 kPa). The ratio of hydrogen to carbon monoxide in the reformed syngas 8 was 0.93 mol/mol.

The examples show that the process of the present invention can produce a high carbon monoxide partial pressure and a low hydrogen partial pressure in the stripping gas 28 while still supplying a reformed syngas 8 with a hydrogen to carbon monoxide ratio similar to that in the syngas stream 3 fed to the membrane separator 200. The carbon monoxide in the synthesis gas stream 3 is therefore effectively used twice in the process, first in the stripping gas 28 and then in the reformed synthesis gas 8 fed to the hydroformylation reaction zone. The result is that the advantage of a high carbon monoxide partial pressure in the stripping gas 28 is achieved without wasting any carbon monoxide in the synthesis gas stream 3.

It will be understood by those skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that changes and modifications are possible without departure from the scope of the invention as defined by the appended claims.