Process for hydroformylation involving the removal of dissolved hydrogen

Abstract

A process for producing aldehydes is disclosed, the process comprising: hydroformylating an olefin using a hydroformylation catalyst to form an aldehyde, recovering an effluent stream comprising the aldehyde, hydrogen, and the hydroformylation catalyst, passing the effluent stream through a stripper, contacting the effluent stream with a strip gas in the stripper to produce a stripped effluent stream having a lower hydrogen concentration than the effluent stream, and recovering the stripped effluent stream.

Description

[Technical Field]

[0001] The present invention relates to a process for hydroformylation of olefins to produce aldehydes. Specifically, the present invention relates to a process for hydroformylation of a mixture of C8 olefin isomers to produce C9 aldehydes. The present invention also relates to a process for hydroformylation of olefins to produce aldehydes, comprising removing dissolved hydrogen from the reactor product before it enters a separation unit. [Background technology]

[0002] The production of aldehydes by hydroformylation of olefins is carried out industrially and on a large scale. Aldehydes are typically intermediate products in the production of alcohols, acids, or esters. A well-known process for producing such products is the LP Oxo process, provided by Dow and Johnson Matthey Davy Technologies. In a typical flow sheet, hydroformylation is carried out in the liquid phase using a ligand-rhodium catalyst, as described, for example, in U.S. Patent No. 4,148,830 or U.S. Patent No. 5,087,763. The liquid-phase reactor effluent is removed from the hydroformylation reactor and fed into 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 contains a solvent, rhodium, ligand, and other components present in the reactor.

[0003] Many variations of molecules that can function as ligands are known. Commercial ligands are often phosphines such as triphenylphosphine, monophosphites such as trimethylolpropane phosphite or tris(2,4-di-tert-butylphenyl) phosphite, bisphosphites, or mixtures of any of these. International Publication No. 2016089602 lists various ligands. Of these three types of ligands, monophosphites are considered to be the most active, but they are also thought to have the weakest ligand-to-rhodium interaction, which is thought to make the catalytic complex unstable.

[0004] A typical catalyst separation unit includes an evaporator that evaporates a portion of the reactor effluent. This yields a vapor phase containing aldehyde products and essentially no catalyst, and a liquid phase containing a liquid catalyst solution. The vapor phase is transported for further processing. Further processing generally includes an aldehyde purification step, where unconverted olefins and paraffins are removed along with dissolved synthesis gas and other light components. The aldehydes thus produced can be used as intermediates for other products such as alcohols, acids, or esters, and are typically used as plasticizers.

[0005] The evaporation of aldehydes in the reactor effluent within the catalyst separation unit is aided by a decrease in pressure and an increase in temperature within the evaporator. However, liquid catalyst solutions are usually prone to decomposition in various forms, resulting in a loss of activity and rhodium. Since rhodium is a valuable precious metal, it is desirable to keep rhodium consumption as low as possible to maintain process economics. This often dictates the maximum allowable temperature within the evaporator. Evaporation can be increased by operating the evaporator at a low pressure. A low total pressure means a decrease in the partial pressure of the aldehyde, which increases aldehyde evaporation and is therefore particularly useful for relatively heavy aldehydes. However, low total pressure, especially vacuum, increases the volume of the equipment and therefore makes it more expensive. Pressures below atmospheric pressure also pose a risk of air entering the process. This can lead to oxidation of the aldehyde and / or ligands, both of which contribute to increased costs.

[0006] Therefore, it is desirable to stabilize the catalyst to prevent its loss and, preferably, enable its use at high temperatures and pressures exceeding atmospheric pressure.

[0007] U.S. Patent No. 6,500,991 aims to stabilize a catalyst, which is done by cooling the catalyst solution obtained from an evaporator and adding a carbon monoxide-containing gas to the liquid, or by adding carbon monoxide to a flash vessel before catalyst separation.

[0008] European Patent No. 2297077 describes the use of a circulating strip gas to reduce the partial pressure of aldehydes and maintain an overall positive pressure. In the catalyst separation unit, the reactor effluent is fed into the evaporator together with the strip gas, and both flow in parallel through the evaporator. The strip gas is essentially aldehyde-free and therefore reduces the partial pressure of aldehydes in the evaporator, thereby increasing the driving force for aldehyde evaporation from the reactor effluent. The evaporator may also be heated to further promote evaporation. The resulting vapor mixture, containing aldehydes and strip gas, is then separated from the remaining liquid catalyst solution. The liquid catalyst solution is returned to the reactor, and the vapor mixture is fed into the condenser. In the condenser, the temperature of the vapor mixture is reduced, resulting in the condensation of essentially all aldehydes, which are separated from the remaining vapor. The remaining vapor is then recompressed to the evaporator inlet pressure and reused as strip gas.

[0009] International Publication No. 2016089602 describes reducing catalyst loss by adding carbon monoxide to the evaporator strip gas. It also suggests that lowering the hydrogen partial pressure in the strip gas may contribute to reducing catalyst loss. Carbon monoxide can be obtained by separating the synthesis gas into a hydrogen-containing stream and a makeup strip gas stream.

[0010] Hydrogen dissolved in the reactor effluent can be released into the circulating strip gas and, if not purged, can accumulate. As a result, large flows of makeup gas, such as carbon monoxide, may be required to maintain a sufficiently low hydrogen concentration in the circulating strip gas. There is still a need for a process that can address the problems surrounding hydrogen in the reactor effluent while minimizing the need for additional synthesis gas feedstock and energy input, and that can reduce the size of the equipment required to generate a CO-rich flow for the strip gas and recover the purged CO-rich gas for useful purposes.

[0011] The present invention aims to overcome the drawbacks associated with the prior art. Specifically, but not limited to, the present invention aims to provide an improved and more cost-effective process for hydroformylation of olefins to aldehydes. [Overview of the Initiative]

[0012] According to a first aspect of the present invention, a process for generating an aldehyde is provided, the process is a. Hydroformylating olefins using a hydroformylation catalyst to form aldehydes, b. To recover spilled logistics containing aldehydes, hydrogen, and hydroformylation catalysts, c. Passing the outgoing logistics through a stripper, d. To bring the outflow material into contact with the strip gas within the stripper to generate a stripped outflow material having a lower hydrogen concentration than the outflow material, e. Including the recovery of stripped spilled logistics.

[0013] Therefore, the present invention requires a stripper to remove hydrogen from the effluent before it enters the catalyst separation unit. As used herein, the stripper may encompass any suitable unit for removing hydrogen from a solution. In the catalyst separation unit, the catalyst is separated from the effluent, concentrated in the liquid phase, and preferably recycled to a hydroformylation reactor to participate in the reaction again. Catalyst separation is generally carried out at high temperature and under reduced pressure. Under these conditions, it has been found that the presence of hydrogen can be detrimental to catalyst stability. Furthermore, hydrogen dissolved in the reactor effluent can be released into the circulating strip gas and accumulate if not purged. As a result, a large flow rate of makeup gas, such as carbon monoxide, is required to maintain the hydrogen concentration in the circulating strip gas at a sufficiently low level.

[0014] The present invention provides a method for removing dissolved hydrogen from the reactor effluent upstream of the catalyst separation unit. By reducing the amount of hydrogen entering the strip gas as dissolved gas from the reactor effluent, the present invention dramatically reduces the purging required in the strip gas loop to maintain the low hydrogen concentration necessary for catalyst stability. Since less purging is required, the process therefore requires less makeup gas, such as carbon monoxide. As a direct result, the process of the present invention reduces equipment costs in the separation package and lowers the recompression requirement for returning the purge to the hydroformylation reactor. Thus, the present invention offers the significant advantages of maintaining catalytic activity, minimizing the need for additional feedstock, and enabling smaller equipment. Furthermore, the gas flow required to maintain the low partial pressure of hydrogen in the circulating strip gas is dramatically reduced, and therefore, the present invention results in a substantial reduction in overall power consumption and equipment costs. In the proposed scheme, the flow rate of CO-rich gas to the stripper is less than 1.5 mol% of the makeup gas required to achieve the same hydrogen content as the cycle gas in an arrangement where the CO-rich gas is directly supplied to the loop as makeup gas.

[0015] The removal of hydrogen from the effluent can be achieved by bringing the effluent into contact with the strip gas. Contact between the effluent and the strip gas can be achieved by any suitable method. Examples include, but are not limited to, parallel or counter-flow of the strip gas and effluent through a column containing structured or random packing, or bubbling the strip gas through a flash vessel containing the effluent. In some embodiments, the effluent may be flushed at a lower pressure in the flash vessel before being introduced into the stripper.

[0016] In some embodiments, the strip gas includes carbon monoxide, carbon dioxide, alkanes, or a combination thereof. Preferably, the strip gas includes carbon monoxide. The process may include feeding a synthesis gas stream into a separation system, separating the synthesis gas stream into a hydrogen-rich stream and a carbon monoxide-rich stream in the separation system, and using the carbon monoxide-rich stream as the strip gas. Preferably, the carbon monoxide-rich stream contains hydrogen in amounts of 0 mol% to 10 mol%, less than 5 mol%, or less than 2 mol%. Preferably, the carbon monoxide-rich stream contains carbon monoxide in amounts of 90 mol% to 100 mol%, greater than 95 mol%, or greater than 98 mol%. The separation system may include, for example, a membrane or a cryogenic distillation unit.

[0017] In some embodiments, the process includes recovering a spent strip gas stream containing strip gas and hydrogen from a stripper. The spent strip gas stream can be mixed with a hydrogen-rich stream to form a recombined synthesis gas stream, which can then be fed into a hydroformylation reactor.

[0018] The process may include splitting the synthesis gas stream from the synthesis gas feed stream to the hydroformylation reactor to the synthesis gas feed stream that is fed to the separation system. In some embodiments, the recombined synthesis gas stream can be fed to the hydroformylation reactor by mixing the recombined synthesis gas stream with the synthesis gas feed stream.

[0019] Preferably, hydrogen should be completely or substantially removed from the stripped effluent. In some embodiments, the stripped effluent contains hydrogen in amounts of less than 0.5 mol%, less than 0.1 mol%, less than 0.05 mol%, or 0 mol% to 0.02 mol%. The process may further include feeding the stripped effluent into an evaporator and recovering a vapor stream from the evaporator containing (1) an aldehyde and (2) a liquid catalyst recirculation stream containing a hydroformylation catalyst for recirculation to a hydroformylation reactor. In some embodiments, the hydrogen concentration in the evaporator is 5 mol% or less, 3 mol%, or 1 mol%. The process may also include feeding a gas containing carbon monoxide into the evaporator.

[0020] The stripped effluent can proceed to a catalyst separation unit for separating catalysts, such as ligand-rhodium catalysts, from the effluent in the hydroformylation reaction zone, where the circulating strip gas can be used in an evaporator to separate the product aldehyde from the ligand-rhodium catalyst, where the circulating strip gas can be purged, for example, to prevent the accumulation of hydrogen and inert components, and a makeup carbon monoxide-rich gas is added to the circulating strip gas, typically from a synthesis gas separation unit. The still carbon monoxide-rich purged strip gas can be combined with a hydrogen-containing stream, typically from a synthesis gas separation unit, to form a reformed synthesis gas stream that is fed into the reaction zone.

[0021] The makeup strip gas stream may contain carbon monoxide and is preferably carbon monoxide-rich. Preferably, the makeup strip gas stream contains 50-100 mol% carbon monoxide, more preferably 70-100 mol% carbon monoxide, even more preferably 80-100 mol% carbon monoxide, and most preferably 97-100 mol% carbon monoxide. A higher concentration of carbon monoxide is advantageous because it allows for a higher carbon monoxide concentration in the strip gas. Preferably, the hydrogen-containing stream contains 50-100 mol% hydrogen, more preferably 70-100 mol% hydrogen, even more preferably 80-100 mol% hydrogen, and most preferably 95-100 mol% hydrogen. In some embodiments, the partial pressure of carbon monoxide in the vapor mixture leaving the evaporator may be at least 15 psi (103 kPa), preferably at least 20 psi (138 kPa). For example, the partial pressure of carbon monoxide in the vapor mixture leaving the evaporator may be at least 15 psi (103 kPa) to 200 psi (1379 kPa) or less. The partial pressure of hydrogen in the vapor mixture leaving the evaporator may be, for example, 10 psi (69 kPa) or less, 5 psi (34 kPa) or less, or 1 psi (6.9 kPa) or less.

[0022] This process may include separating a syngas stream into a hydrogen-containing stream and a makeup stripping gas stream that is fed to a stripping section and / or an evaporator, the syngas stream being split from a main syngas feed and containing carbon monoxide and hydrogen. As described above, such a syngas separation section can be located upstream of the hydrogen stripper. The syngas feed is recombined with carbon monoxide and hydrogen from the stripping gas in the evaporator and the stripping gas in the hydrogen stripper, and with the hydrogen-rich stream from the syngas separation section, and then fed to the reaction zone to produce a reformed syngas stream. In some embodiments, for example, the syngas feed may reach the limits of the process battery, and a portion of the syngas feed may be separated into a makeup stripping gas stream and a hydrogen-containing stream, and another portion of the syngas feed may be fed to the reaction zone. In such a case, some of the syngas feed effectively bypasses the catalytic separation unit. Such an arrangement can be beneficial in balancing the need to feed syngas to the reaction zone and the need to feed carbon monoxide to the stripping gas. In such embodiments, the molar ratio of the portion of the syngas feed separated into the makeup stripping gas stream and the hydrogen-containing stream to the portion of the syngas feed fed to the reaction zone as a fresh syngas stream can preferably be from 0.01 to 1. More preferably, the molar ratio is from 0.05 to 0.5, and most preferably, the molar ratio is from 0.1 to 0.3. This molar ratio can be selected based on the separation efficiency, for example, the membrane separation efficiency if a membrane is used for separation. For example, if the makeup stripping gas stream contains a relatively high level of hydrogen, a greater flow rate of the makeup stripping gas stream can be used.

[0023] The molar ratio of carbon monoxide to olefin fed into the reaction zone is preferably about 1. Separation of the synthesis gas stream into a hydrogen-containing stream and a makeup strip 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 can increase the carbon monoxide concentration in the makeup strip gas stream to at least 95 mol%, or preferably at least 99 mol%, in an economical manner. However, such high purity may require a fast flow rate of synthesis gas to the membrane separation unit, and therefore it is important that carbon monoxide is not wasted. This is achieved in the present invention by recombining the purged strip gas stream and the hydrogen-rich stream to generate a reformed synthesis gas stream, which is then sent to the reaction zone. Alternatively, or in addition, the separation of the synthesis gas stream into a hydrogen-containing stream and a strip gas stream may be carried out using the COSORB process or a variation thereof, as described, for example, in "The absorption of carbon monoxide in COSORB solutions: absorption rate and capacity" by J.A. Hogendoorn, W.M. van Swaaij, GF. Versteeg, Chem.Eng.Journ. 59 (1995) 243-252 or U.S. Patent No. 4,950,462 or U.S. Patent No. 5,382,417. Alternatively, or in addition, the separation of the synthesis gas stream into a hydrogen-containing stream and a strip gas stream may be carried out using low-temperature absorption with liquid nitrogen.

[0024] The molar ratio of hydrogen to carbon monoxide in the syngas stream is preferably from 0.5 to 2.0. The most desirable ratio of hydrogen to carbon monoxide may depend on the desired partial pressures of hydrogen and carbon monoxide in the reaction zone. Preferably, the molar ratio of hydrogen to carbon monoxide in the reformed syngas stream is, for example, equivalent to the molar ratio of hydrogen to carbon monoxide in the syngas stream and varies within a range of within 10% thereof. The molar ratio of hydrogen to carbon monoxide in the reformed syngas stream may preferably be from 0.5 to 2.0. The partial pressures of hydrogen and carbon monoxide within the reaction zone may affect the hydroformylation reaction, rate, and selectivity. When the molar ratio of hydrogen to carbon monoxide in the reformed syngas stream is equivalent to the molar ratio of hydrogen to carbon monoxide in the syngas stream, control of the partial pressures of carbon monoxide and hydrogen in the reaction zone may be simpler and advantageous.

[0025] The evaporator is preferably a falling-film evaporator, but may also be other types of evaporators, such as a vessel having structured or random packing. The strip gas may be fed to the evaporator in a co-current or counter-current flow with the reactor effluent.

[0026] Since the recycled strip gas is at a lower pressure than the strip gas due to the pressure drop in the process, it is preferable to provide a compressor to compress the recycled strip gas before it is combined with the makeup strip gas. Also, it is preferable to provide a compressor to compress the reformed syngas stream before it is fed to the reaction zone. Preferably, the purged strip gas stream is purged from the recycled strip gas after the recycled strip gas has been compressed. In this way, the purged strip gas stream may be at a pressure suitable for forming a reformed syngas stream in combination with a hydrogen-containing stream, which may then be compressed before being fed to the reaction zone, avoiding the need to provide separate compressors for the recycled strip gas and the purged strip gas stream.

[0027] Typically, the reaction zone operates at approximately 20 bar (2 MPa), for example, 15–40 bar (1.5–4.0 MPa), while the evaporator operates at approximately 8 bar (800 kPa), for example, 1–20 bar (100–2000 kPa). However, pressures of 50–235 bar (5–23.5 MPa) are also known to operate the reaction zone.

[0028] Preferably, the olefin is C2-C 16 It is an olefin, more preferably C4~C 12 The olefin is preferably a C8 olefin. The olefin is preferably a monoolefin. The olefin is preferably an acyclic olefin, such as a linear or branched olefin. For example, the olefin may be propylene or n-butene. The olefin is preferably a C8 olefin, but may be, for example, octene, dimerized butene, or oligomerized ethylene. Preferably, the aldehyde has one more carbon than the olefin. Therefore, the aldehyde is preferably C3-C 17 Aldehydes, more preferably C5~C 13 An aldehyde, most preferably a C9 aldehyde, is used. Those skilled in the art will understand that the aldehyde produced depends on the olefin used.

[0029] The present invention can be used with any suitable ligand system that benefits from a carbon monoxide-rich strip gas. Preferably, the ligand is a phosphine such as triphenylphosphine, a monophosphine such as trimethylolpropane phosphine or tris(2,4-di-tert-butylphenyl) phosphine, a bisphosphine, or a mixture thereof.

[0030] The reactor effluent typically contains additional components in addition to the product aldehyde and ligand-rhodium catalyst. These additional components may include olefins and paraffins, ligand decomposition products, ligand stabilizers, aldehyde oligomers (sometimes called "heavy"), water, and dissolved gases. The vapor mixture exiting the evaporator typically contains additional components in addition to the product aldehyde and strip gas. These additional components may include olefins, paraffins, and other light components. Olefins and paraffins typically condense in the condenser, while the light components remain in the reuse strip gas, their levels controlled by purging the purged strip gas stream.

[0031] The product aldehyde stream is preferably a liquid product aldehyde stream.

[0032] A reaction zone will be understood to mean one or more hydroformylation reactors. Typically, a reaction zone comprises one, two, three, or four reactors. The reactors may be connected in series, for example. Feed flows, such as fresh synthesis gas streams and reformed synthesis gas streams, may be supplied to one or more of the reactors, and reactor effluents sent to evaporators may be collected from one or more of the reactors.

[0033] When it is said that components such as product aldehydes evaporate into a strip gas, it will be understood that the majority of the components evaporate in this way. Trace amounts of the components may remain in the liquid phase, for example, in equilibrium with the vapor components in the vapor phase. At least 50 mol%, preferably at least 60 mol%, and more preferably at least 70 mol% of the components may evaporate in this way. Essentially, all components can evaporate in this way. Similarly, when it is said that components such as product aldehydes are separated from a vapor mixture, it will be understood that the majority of the components are separated in this way. Trace amounts of the components may remain. At least 75 mol%, preferably at least 90 mol%, and more preferably at least 95 mol% of the components can be separated in this way. Essentially, all components can be separated. [Brief explanation of the drawing]

[0034] Now, with reference to the attached diagrams, embodiments of the present invention will be described as examples, not in a restrictive sense. [Figure 1] This is a block diagram of the flow sheet used when implementing the present invention. [Figure 2] This is a process flow diagram of a part of the process shown in Figure 1 when implementing the present invention. [Modes for carrying out the invention]

[0035] In Figure 1, the olefin feed 1 is fed into the hydroformylation reaction zone 100. The reaction zone 100 comprises at least one reactor, and possibly two or three reactors, and the reactor effluent 11 is sent to the catalyst separation unit 101. The liquid ligand-rhodium catalyst solution 12, which typically contains heavy compounds such as dimers or trimers, is reused 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 sent to the aldehyde purification unit 102, from which purified aldehyde 15 is recovered. The olefin and paraffin 14 are also recovered from the aldehyde purification unit 102.

[0036] The synthesis gas feed 2 is divided into a fresh synthesis gas flow 4 that is fed directly to the reaction zone 100 as part of the mixed synthesis gas feed flow 10, and a synthesis gas flow 3 that is fed to the membrane separation unit 200. In the membrane separation unit 200, the synthesis gas flow 3 is separated into a makeup strip gas flow 5 and a hydrogen-containing flow 6. The former is sent to the catalyst separation unit 101, and the latter is combined with a purged strip gas flow 7 to form a reformed synthesis gas flow 8, which is compressed in the compressor 201 and fed to the reaction zone 100 as part of the mixed synthesis gas feed flow 10 9. Purge may be included, for example, from one or more of flows 6, 7, 8, or 9 for operational reasons, but is preferably avoided in order to avoid the loss of the reformed synthesis gas.

[0037] The catalyst separation unit 101 is shown in detail in Figure 2. In Figure 2, the synthesis gas feed 2 is divided into a fresh synthesis gas flow 4 that is fed directly to the reaction zone 100 as part of the mixed synthesis gas feed flow 10, and a synthesis gas flow 3 that is fed to the membrane separation unit 200. In the membrane separation unit 200, the synthesis gas flow 3 is separated into a strip gas flow 5 and a hydrogen-containing flow 6. The former is sent to the stripper 202, and the latter is combined with the purged strip gas flow 7 and compressed to form a reformed synthesis gas flow 9, which is fed to the reaction zone 100 as part of the mixed synthesis gas feed flow 10. The reactor effluent 11 is fed to the stripper 202, which operates to produce a stripped effluent flow 12 having a lower hydrogen concentration than the effluent flow 11, and the effluent flow 12 is passed through the catalyst separation unit.

[0038] Example 1 The following examples were created using the commercially available simulation package SimSci ProII v10.1. The use of simulation to evaluate new processes is well-established in the field of chemical engineering.

[0039] The reactor effluent at 90°C, containing 0.8 mol% dissolved hydrogen, is fed into a stripping column operating at 13.5 bergs at the top of the column.

[0040] At 25 bergs, 3.6 mol% of the plant synthesis gas feed is fed into the membrane separation unit. So A CO-rich flow is generated. CO-rich flow 5 contains 96.4 mol% CO and 0.8 mol% hydrogen. Aldehyde reactor product production: 1.36 Nm³ per ton 3 CO-rich flow rate 5 The CO-rich flow is fed to the bottom of a stripping column containing seven theoretical plates. This CO-rich flow is brought into contact with the reactor effluent 11 inside the column, generating a stripped effluent flow at the bottom of the stripping column that mainly contains 0.08 mol% hydrogen in C8 and C9 oxygenates.

[0041] The stripped effluent stream exiting the stripping column is then fed at 12 barg Manipulated to the catalyst separation unit, So and the product oxide is At 140°C, 3,240 Nm³ per ton of aldehyde reactor product 3 cycle gas and contacted to Most of the reactor products evaporate, the catalyst solution recycled back to the reactor remaining . The hydrogen concentration in the cycle gas is 1.56 mol%.

[0042] The purged strip gas stream exiting the top of the stripping column is cooled to 45°C to remove condensable hydrocarbons, This and returned to the stripper column. The cooled and purged strip gas is then mixed with the hydrogen-rich gas from the membrane separation unit and recompressed to 25 barg and returned to the reactor.

[0043] For comparison and to demonstrate the advantages of the present invention, the configuration from the prior art was also simulated using the same commercially available simulation package SimSci ProII v10.1.

[0044] With the same composition as above, Similarly at 90°C, and ta0 .8 mol% dissolved hydrogen-containing reactor effluent is fed directly at 12 barg Manipulated to the catalyst separation unit, The product oxygenates are converted at 140°C, with a yield of 3,240 Nm³ per ton of aldehyde reactor product. 3 of contacted with the cycle gas, As a result, most of the reactor products evaporate. and the catalyst solution recycled back to the reactor remaining .

[0045] The CO-rich makeup stream is generated by sending all of the plant supplied to syngas to the membrane separation unit. 37.14 Nm³ per ton of aldehyde reactor product 3 A CO-rich makeup flow is generated. It is added to the cycle gas. 38.79 Nm³ per ton of aldehyde reactor product 3 of The purge is removed from the cycle gas to purge hydrogen and inert components. The cycle gas contains 1.94 mol% hydrogen.

[0046] This embodiment demonstrates that the process of the present invention achieves a low hydrogen concentration in the cycle gas using a CO-rich gas flow rate far lower than required in the configurations disclosed in the prior art, thereby reducing energy consumption and equipment size.

[0047] Example 2 General Procedure: All tests were performed in a multi-well heating block equipped with six 100 mL autoclaves, and several tests were duplicated for accuracy. Internal thermocouples were used to control the temperature, and the process temperature was measured as a cross-check by double-checking against one autoclave with an internal thermocouple. Phosphorus ligand (molar excess) and rhodium stock solution (prepared by dissolving Rh(acac)(CO)2 in toluene, and filled with 50 mL of the solution) were transferred to 100 mL autoclaves, sealed, and purged with synthesis gas (CO:H2 molar ratio = 1:1, 3 × 100 psi(g)). All autoclaves were then pressurized with synthesis gas and allowed to stand in situ to form the active catalyst, and then allowed to stand to cool to ambient temperature. After cooling, samples (1.5 mL) from the autoclaves were taken for rhodium analysis by ICP-OES analysis. Next, the autoclave was purged with a suitable test gas (synthesis gas, CO, H2, or N2), and then pressurized with the test gas to the test pressure (as outlined in Table 1 below). The autoclave was then removed from the heating block, and the reaction was carried out for the allocated time before cooling to room temperature. At the completion of the test, additional samples were removed from the autoclave and analyzed for rhodium concentration by ICP-OES to investigate the loss of soluble rhodium during the experimental process. The rhodium loss rate was then calculated as follows: ((1-[Rh]) 最終 ) / [Rh] 初期 ) × 100.

[0048] Table 1 below shows the rhodium loss over time, illustrating its dependence on different gas compositions with varying pressures. Entries 1 and 2 show high rhodium loss under a synthesis gas atmosphere at 120°C, with only slight improvement at higher pressures (approximately 90%). Under the same conditions but with nitrogen (entry 3), rhodium loss is only 5%, demonstrating a significant improvement in rhodium loss. In a CO-only atmosphere (entry 4), rhodium loss was not apparent. This clearly demonstrates the advantages of operating in the absence of hydrogen, but also the increased stabilizing effect of CO on nitrogen.

[0049] When operating at higher temperatures (130°C, entries 5-8), higher pressures were investigated in an attempt to increase the stability of the rhodium catalyst. Using a 1:1 synthesis gas composition (entry 5), the loss was 93%. Operating at higher pressures with a high H2:CO ratio (entry 6) reduced the loss to 69%. Complete loss of rhodium was observed in a hydrogen-only atmosphere (entry 7). However, even under these forced conditions, the rhodium loss under a pure CO atmosphere was only 12% (entry 8). While the loss was reduced using a high H2:CO atmosphere (entry 6), it is assumed that the high partial pressure of CO has a stabilizing effect on the catalyst solution. However, the results from both sets of experiments show a clear benefit in terms of rhodium loss from the catalyst solution when using a CO-only atmosphere.

[0050] [Table 1]

[0051] Those skilled in the art will understand that the embodiments described above are provided as examples only, and not in any restrictive sense, and that various modifications and alterations are possible without departing from the scope of the invention as defined by the appended claims.

Claims

1. A process for generating aldehydes, a. Hydroformylating an olefin using a hydroformylation catalyst to form the aldehyde, b. To recover the spilled logistics containing the aldehyde, hydrogen and the hydroformylation catalyst, c. Passing the aforementioned outflow logistics through a stripper, d. To bring hydrogen from the outflow material into contact with a stripping gas within the stripper to generate stripped outflow material having a lower hydrogen concentration than the outflow material, e. A process comprising recovering the stripped spillage.

2. The process according to claim 1, wherein the strip gas contains carbon monoxide.

3. The process according to claim 2, wherein the process comprises feeding a synthesis gas flow into a separation system, separating the synthesis gas flow into a hydrogen-rich flow and a carbon monoxide-rich flow in the separation system, and using the carbon monoxide-rich flow as the strip gas.

4. The process according to claim 3, wherein the separation system includes a membrane or a cryogenic distillation unit.

5. The process according to claim 3 or 4, wherein the process comprises recovering a spent strip gas stream containing the strip gas and hydrogen from the stripper; mixing the spent strip gas stream with the hydrogen-rich stream to form a remixed synthesis gas stream; and feeding the remixed synthesis gas stream to a hydroformylation section.

6. The process according to any one of claims 3 to 5, wherein the process comprises separating the synthesis gas feed stream from the synthesis gas feed stream to the hydroformylation section from the synthesis gas stream that is fed to the separation system.

7. The process according to claim 6, as dependent on claim 5, wherein the remixed synthesis gas flow is fed to the hydroformylation section by mixing the remixed synthesis gas flow with the synthesis gas feed flow.

8. The process according to any one of claims 1 to 7, wherein the hydroformylation catalyst comprises a homogeneous metal-ligand catalyst.

9. The process according to claim 8, wherein the homogeneous metal-ligand catalyst comprises rhodium.

10. The process according to claim 8 or 9, wherein the metal-ligand catalyst comprises an organophosphite ligand or an organophosphine ligand.

11. The process according to claim 10, wherein the organophosphite ligand or the organophosphine ligand comprises triphenylphosphine.

12. The process according to any one of claims 1 to 11, wherein the process comprises feeding the stripped outflow to an evaporator and recovering from the evaporator a vapor stream comprising (1) an aldehyde and (2) a liquid catalyst recirculation stream comprising a hydroformylation catalyst for recirculation to a hydroformylation section.

13. The process according to claim 12, wherein the molar composition of hydrogen in the stripped effluent is 5 mol% or less.

14. The process according to claim 12 or 13, wherein the process comprises feeding a gas containing carbon monoxide to the evaporator.

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