Individual parallel zone hydroformylation reaction

Abstract

The present invention provides a process for the hydroformylation of an olefin to produce positive (N) and iso (I) aldehydes in an N: I ratio RA, the process comprising hydroformylating an olefin with hydrogen and carbon monoxide in the presence of a ligand-metal catalyst; wherein the hydroformylation is carried out in at least two separate parallel hydroformylation zones, each hydroformylation zone comprising one or more hydroformylation reactors in series; and each individual hydroformylation zone produces N and I aldehydes at a different N: I ratio than the other hydroformylation zones; wherein the process comprises the steps of: i) supplying an olefin feed stream to each individual hydroformylation zone; ii) supplying a stream comprising hydrogen and carbon monoxide to each individual hydroformylation zone; iii) recovering an aldehyde product stream from each individual hydroformylation zone; wherein the N: I ratio RA is the total N: I ratio contained in the aldehyde product stream.

Description

Technical Field

[0001] The present invention relates to a process for the hydroformylation of olefins to form aldehydes. In particular, the present invention relates to controlling the linear to branched aldehyde isomer ratio in a hydroformylation process that uses separate hydroformylation zones that produce linear and branched aldehydes in different ratios. Background Art

[0002] Hydroformylation of olefins is carried out industrially on a large scale to produce aldehydes. Aldehydes are generally intermediate products in the production of alcohols, acids or esters. A known method for producing such products is the low pressure oxo synthesis (LP Oxo) method provided by Dow and Johnson Matthey Davy. In a typical flow, for example, as described in US4148830 or US5087763, hydroformylation is carried out in liquid phase using a ligand-rhodium catalyst. The liquid phase reactor effluent leaves the hydroformylation reactor and is fed to a catalyst separation unit, where a liquid catalyst solution is separated from the product aldehyde. The liquid catalyst solution is then returned to the reactor. The liquid catalyst solution generally comprises a solvent, rhodium, a ligand and other components present in the reactor.

[0003] Many variants of molecules that can be used as ligands are known. The ligands used commercially are typically organic monophosphines, such as triphenylphosphine; organic monophosphites, such as trimethylolpropane phosphite or tris(2,4-di-tert-butylphenyl)phosphite; organic polyphosphites, such as organic diphosphites; or mixtures of any of these. WO2008 / 115740, WO2011 / 087690, WO2010 / 117391, and WO2016 / 089602 list various ligands. In addition, organic polyphosphines, such as those disclosed in WO2019 / 231610, can be used. Among these types of ligands, organic monophosphites are considered to be the most active, but may have the weakest ligand-rhodium interaction. In the case of, for example, propylene hydroformylation, commercially available organic monophosphites typically produce aldehydes with a relatively low linear to branched isomer ratio (e.g., as low as about 0.5 to 1). Commercially available organomonophosphines generally produce aldehydes with relatively high linear to branched isomer ratios, and when used in combination with organopolyphosphines, the ratios are somewhat higher. Commercially available organodiphosphites generally have the strongest ligand interactions with rhodium and produce aldehydes with relatively high linear to branched isomer ratios (e.g., greater than about 20:1).

[0004] Usually, it is desirable to obtain high straight chain and branched chain isomer ratios, mainly because the high value downstream products such as plasticizers need straight chain compounds. This can generally be realized, for example, using an organic diphosphite part during hydroformylation. However, it is also possible to need a lower ratio of straight chain aldehyde and branched chain aldehyde, for example, for the production of neopentyl glycol. Especially, the ratio between the best ratio that can be provided using organic monophosphite or organic polyphosphite alone.

[0005] WO2008 / 115740 discloses a method for controlling the ratio of linear to branched aldehydes using different ratios of organomonophosphite to organopolyphosphite ligands in the same reaction solution. However, this method may have limitations, especially if neither ligand-rhodium complex is operated at its optimal performance conditions. Summary of the invention

[0006] The present invention provides a method for the hydroformylation of olefins to obtain a catalyst having an N:I ratio R A A process for producing normal (N) and iso (I) aldehydes comprising hydroformylating an olefin with hydrogen and carbon monoxide in the presence of a ligand-metal catalyst;

[0007] wherein the hydroformylation is carried out in at least two separate parallel hydroformylation zones, each hydroformylation zone comprising one or more hydroformylation reactors connected in series; and

[0008] Each individual hydroformylation zone produces N and I aldehydes at a different N:I ratio than the other hydroformylation zones;

[0009] The method comprises the following steps:

[0010] i) supplying an olefin feed stream to each individual hydroformylation zone;

[0011] ii) supplying a stream comprising hydrogen and carbon monoxide to each individual hydroformylation zone;

[0012] iii) recovering an aldehyde product stream from each individual hydroformylation zone;

[0013] Where the N:I ratio R A is the total N:I ratio contained in the aldehyde product stream.

[0014] Advantageously, the loss of metal catalyst during the process can be reduced compared to processes such as disclosed in WO2008 / 115740, in which the N:I ratio is controlled by using different ratios of different ligand types in the same reaction liquor. This in turn has benefits in terms of reduced equipment inventory, capital costs and operating costs. Advantageously, for a particular set of operating conditions and ligand-metal catalyst in each hydroformylation zone, R AThe relative flow rates of the aldehyde product streams from each hydroformylation zone can be controlled. Thus, another advantage of the present invention is that the N:I ratio R can be rapidly varied by varying the flow rates to each hydroformylation zone. A , which is different from the system disclosed in WO2008 / 115740, in which the N:I ratio is controlled by the ratio of the organic monophosphite to the organic polyphosphite ligand in the same reaction solution. It should be understood that substantially the same olefins are supplied to each individual hydroformylation zone. For example, the olefin feed stream can be distributed between the individual hydroformylation zones. Therefore, the method may include dividing the olefin feed stream into the feed stream for each individual hydroformylation zone. The flow ratio of the olefin feed stream entering each zone can be used as a part of the N:I ratio control. The flow of the aldehyde product stream from the hydroformylation zone can be controlled by changing the olefin feed stream (comprising the relative flow rate of the olefin feed stream entering each individual hydroformylation zone) and the stream comprising carbon monoxide and hydrogen. Based on the desired N:I ratio R A The skilled person can determine the required relative feed flow rates based on the characteristics of the ligand-metal catalyst used and the operating conditions in each hydroformylation zone. In the example, the olefin feed is split and fed to the first hydroformylation zone and the second hydroformylation zone in proportion to the capacity required for each zone. The stream containing hydrogen and carbon monoxide is also preferably split to each individual hydroformylation zone in proportion to the capacity required for each zone. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of one aspect of the method of the present invention.

[0016] Figure 2 is a schematic diagram of a method according to another aspect of the present invention.

[0017] Figure 3 is a graph showing metal loss in mixed ligand hydroformylation reactions.

[0018] Figure 4 is a graph showing metal loss in a single ligand hydroformylation reaction to produce aldehydes with relatively low N:I ratios.

[0019] Figure 5 is a graph showing metal loss in a single ligand hydroformylation reaction to produce aldehydes with relatively high N:I ratios. DETAILED DESCRIPTION

[0020] Hydroformylation processes, their reagents, conditions and equipment are known, and the hydroformylation step in the present invention can be carried out according to known techniques employed in conventional hydroformylation processes. The process of the present invention uses at least two, preferably two separate parallel hydroformylation zones. Each hydroformylation zone comprises at least one, usually at least two, usually no more than four (e.g., two, three or four) hydroformylation reactors connected in series. The hydroformylation zones are parallel in the sense that the reaction liquids in each separate hydroformylation zone will not mix. The reaction liquids contain solvent, ligand-metal catalyst, free ligands and other components such as solubilizers and stabilizers.

[0021] There may be a small amount of cross-linking of the streams, for example by passing the effluent from a reactor in one hydroformylation zone into a reactor in another hydroacylation zone. The hydroformylation reactor may be a multistage reactor, such as described, for example, in US 5,763,671, in which there are physical barriers which create one or more theoretical stages in each reaction vessel.

[0022] The hydroformylation process in each zone is generally carried out in a continuous manner, in which the olefin is hydroformylated using carbon monoxide and hydrogen in a liquid homogeneous reaction mixture (i.e., the reaction liquid as described above). Suitable inert solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone and cyclohexanone; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated aromatic hydrocarbons including o-dichlorobenzene; ethers such as tetrahydrofuran, dimethoxyethane and dioxane; halogenated paraffins including dichloromethane; paraffins such as heptane. Preferred solvents are aldehyde product and / or oligomers of aldehyde product and reactive olefins.

[0023] Reaction is maintained at a temperature and pressure that is conducive to olefin hydroformylation, and when reactant is exhausted, olefin, carbon monoxide and hydrogen of replenishing amount are supplied in the reaction medium. From the hydroformylation reactor in each hydroformylation zone, take out liquid phase reactor effluent, and be fed to the catalyst separation and product recovery system in each hydroformylation zone, wherein liquid catalyst solution is separated from product aldehyde.Then liquid catalyst solution is returned to reactor.Liquid catalyst solution comprises solvent, metal, part and other components present in reaction solution usually.For example, typical flow chart is described in US4,148,830 or US5,087,763.

[0024] Preferably, the olefin is C3 to C 16 Olefins, more preferably C3 to C 12The aldehyde is preferably a C4 to C5 olefin. The aldehyde is preferably a monoolefin. The olefin is preferably an acyclic olefin, such as a linear olefin or a branched olefin. For example, the olefin may be propylene or n-butene. Preferably, the aldehyde has one more carbon than the olefin. Thus, the aldehyde is preferably a C4 to C5 olefin. 17 Aldehydes, more preferably C4 to C 13 Aldehyde, and most preferably C4 aldehyde. For example, the aldehyde can be butyraldehyde. The skilled person will understand that the aldehyde produced depends on the olefin used.

[0025] The stream comprising hydrogen and carbon monoxide can be obtained from any available source, and is generally synthesis gas, referred to as synthesis gas. Typically, the stream from the same source is used for each hydroformylation zone, and the stream is shunted two or more individual streams to feed the reactor in each hydroformylation zone. The molar ratio of hydrogen to carbon monoxide can be within the scope of the following ratio and include the following ratio: about 1:10 to about 100:1, generally about 1:10 to about 10:1 or about 2:1 to about 1:2. The feed flow rate will depend on ligand-metal catalyst, olefin feed flow rate and other operating conditions. Such flow rate is known and can be easily calculated by the technician.

[0026] The streams comprising hydrogen and carbon monoxide and the olefin feed are typically each passed through a corresponding purification system which helps to protect the hydroformylation catalytic system from low level impurities such as sulfides and chlorides, such systems being known to the skilled person.

[0027] The catalyst metal is generally a transition metal, usually selected from rhodium, cobalt, iridium, ruthenium, iron, nickel, palladium, platinum, osmium, chromium, molybdenum and tungsten and mixtures thereof. Preferably, the metal is selected from rhodium, cobalt, iridium and ruthenium, more preferably selected from rhodium, cobalt and ruthenium, and most preferably the metal is rhodium.

[0028] It should be understood that a hydroformylation zone will operate under the conditions of producing an aldehyde product stream with a higher N:I ratio than another hydroformylation zone, which means that another hydroformylation zone is operated to produce an aldehyde product stream with a lower N:I ratio. Each individual hydroformylation zone usually uses a different ligand-metal catalyst, which generally means that the ligand used in each zone is different. The metal in each zone will usually be the same. Usually, the hydroformylation zone operated under the conditions of producing an aldehyde product stream with a lower N:I ratio operates under the conditions of producing an aldehyde product stream with an N:I ratio of about 2:1 or less, usually at least about 0.5:1. Generally speaking, this zone will comprise a ligand-metal catalyst in which the ligand is an organic monophosphite ligand. Suitable ligands for this reaction zone are known and described, for example, in WO2008 / 115740, WO2011 / 087690, WO2010 / 117391 and WO2016 / 089602. Typically, a hydroformylation zone operating under conditions to produce an aldehyde product stream having a higher N:I ratio is operated under conditions to produce an aldehyde product stream having an N:I ratio of at least about 6:1, typically about 35:1 or less. Generally, this zone will comprise a ligand-metal catalyst in which the ligand is an organomonophosphine ligand or an organopolyphosphite ligand, such as an organodiphosphite or an organopolyphosphite ligand, for example an organotetraphosphine ligand. Suitable organomonophosphine or organopolyphosphite (e.g. organodiphosphite) ligands for this reaction zone are known and described in WO2008 / 115740, WO2011 / 087690, WO2010 / 117391, WO2016 / 089602 and WO2019 / 231610.

[0029] Each hydroformylation zone produces N and I aldehydes in a different N:I ratio, and the N:I ratio R A is the total N:I ratio contained in the aldehyde product stream. In other words, the combined N:I ratios of the individual aldehyde product streams recovered from each hydroformylation zone. Thus, R A represents the weighted average production of each hydroformylation zone. Accordingly, for a specific set of operating conditions and ligand-metal catalyst in each hydroformylation zone, R A The relative flow rates of the aldehyde product streams from each hydroformylation zone can be controlled. Thus, another advantage of the present invention is that the N:I ratio R can be rapidly varied by varying the flow rates to each hydroformylation zone. A This is in contrast to systems such as disclosed in WO2008 / 115740 where the N:I ratio is controlled by the ratio of organomonophosphite to organopolyphosphite ligands in the same reaction solution.

[0030] The flow rate of the aldehyde product stream from the hydroformylation zone can be controlled by varying the olefin feed stream and the stream comprising carbon monoxide and hydrogen. A The relative feed flow rates required can be readily determined by a skilled artisan based on the characteristics of the ligand-metal catalyst used and the operating conditions in each hydroformylation zone. The process of the present invention can be used to produce N:I ratios R in a range where significant but small amounts of I aldehyde are required while the catalyst is operated under optimal performance conditions. A For example, when R A The ratio is at least about 0.5:1 and no greater than about 10:1, and typically at least about 1.5:1 and no greater than about 6:1. Within this range, the process of the present invention can be particularly advantageous because it can result in reactor systems in each individual hydroformylation zone having similar sizes, which is the most economically advantageous situation.

[0031] The N:I ratio can be determined by a variety of methods. One example is to analyze a vapor or liquid stream from a reactor or process stream using techniques such as gas chromatography (GC), infrared (IR), or nuclear infrared (NIR). The product N:I ratio can also be determined by flow measurements from a distillation column used to separate the N and I aldehydes.

[0032] In each hydroformylation zone, the operating conditions that are typically different from those in the other hydroformylation zones are carbon monoxide partial pressure, temperature, metal concentration in the reaction liquid, and ligand concentration in the reaction liquid, including free ligand and ligand complexed with the metal to provide a ligand-metal catalyst. For these operating conditions, a particular ligand-metal catalyst will have a particularly favorable range. Advantageously, each hydroformylation zone can be operated at the optimum performance conditions for the ligand-metal catalyst used in that zone.

[0033] The concentration of the metal-ligand catalyst in the reaction solution of the hydroformylation zone only needs to be the minimum amount necessary for providing the metal concentration required for catalyzing the desired hydroformylation process. Generally speaking, the metal concentration will be at least about 20ppmw, usually at least about 30ppmw. Generally speaking, the metal concentration will be less than or equal to 1000ppmw, usually less than or equal to 600ppmw. When using an organophosphine ligand, particularly an organomonophosphine, the metal concentration can generally be within the range of and include the following concentrations: 100ppmw to 1000ppmw, suitably 200ppmw to 600ppmw. When using an organomonophosphite ligand, the metal concentration can generally be within the range of and include the following concentrations: 20ppmw to 200ppmw, suitably 30ppmw to 100ppmw. When using an organopolyphosphite ligand, particularly an organodiphosphite, the metal concentration can generally be within the range of and include the following concentrations: 20ppmw to 200ppmw, suitably 30ppmw to 100ppmw. For the avoidance of doubt, ppmw means parts per million by weight of the reaction liquid.

[0034] The amount of the ligand in the reaction solution (including free form and complex form) is generally greater than 1 molar equivalent relative to the metal, and can be included in a concentration up to the solubility limit of the ligand in the reaction solution. The specific amount will depend on the nature of the ligand. When using an organic phosphine ligand, especially an organic monophosphine, the amount of the ligand can generally be within the range of and include the following amounts: about 30 molar equivalents to about 500 molar equivalents relative to the metal, and suitably about 100 molar equivalents to about 200 molar equivalents relative to the metal. When using an organic monophosphite ligand, the amount of the ligand can generally be within the range of and include the following amounts: about 4 molar equivalents to about 200 molar equivalents relative to the metal. When using an organic multiphosphite ligand, especially an organic diphosphite, the amount of the ligand can generally be greater than about 1 equivalent and up to about 200 molar equivalents relative to the metal, and suitably up to about 5 molar equivalents. The amount of metal and ligand in the reaction solution can be easily determined by known analytical methods. For example, the metal can be quantified by inductively coupled plasma (ICP) technology, and the ligand can be quantified by 31 Quantification was performed by PNMR or HPLC on aliquots of the reactions.

[0035] The reaction conditions of the hydroformylation process in each reactor can vary widely. Generally speaking, the hydroformylation process can be carried out at a reaction temperature greater than about 25°C, typically greater than about 50°C. The hydroformylation process can be carried out at a reaction temperature less than about 200°C, typically less than about 120°C. When using an organophosphine ligand (including organomonophosphines and organopolyphosphines), it may be beneficial to carry out the hydroformylation reaction at a temperature within the range of or including the following temperatures: about 60°C to about 130°C, suitably about 75°C to about 120°C. When using an organomonophosphite ligand, it may be beneficial to carry out the hydroformylation reaction at a temperature within the range of or including the following temperatures: about 50°C to about 110°C, suitably about 65°C to about 100°C. When using an organopolyphosphite ligand, it may be beneficial to carry out the hydroformylation reaction at a temperature within the range of or including the following temperatures: about 50°C to about 110°C, suitably about 60°C to about 100°C.

[0036] In general, the total gas pressure comprising olefin reactants, carbon monoxide, hydrogen and any inert light gases in the hydroformylation zone reactor can be in the range of about 1 psia (6.9 kPa) to about 10,000 psia (68.9 MPa). Typically, the method can be operated under a total gas pressure comprising olefin reactants, carbon monoxide and hydrogen, which is less than about 2,000 psia (13,800 kPa), and suitably less than about 500 psia (3450 kPa). In the case where the total gas pressure between the hydroformylation zones is different, it is advantageous to pass the effluent from the reactor in the hydroformylation zone operating under a higher carbon monoxide partial pressure into the reactor in another hydroformylation zone. This can improve the efficiency of use of the stream comprising hydrogen and carbon monoxide.

[0037] When using certain ligands, for example, when using organic monophosphite ligands, relatively high carbon monoxide partial pressure is required. This can increase the stability of the ligand system. Accordingly, when using organic monophosphite ligands, the hydroformylation process is usually carried out in the range of the following partial pressure and under the carbon monoxide partial pressure including the following partial pressure: about 1 bar to about 20 bars, usually about 3 bars to about 10 bars. When using some other ligands, a lower carbon monoxide partial pressure can be adopted, and the stability of the ligand system can not be significantly affected. This can improve the activity of the ligand without sacrificing stability. Accordingly, particularly when using organic monophosphites or organic polyphosphites ligands, the hydroformylation process is usually carried out in the range of the following partial pressure and under the carbon monoxide partial pressure including the following partial pressure: about 0.1 bar to about 5 bars, usually about 0.5 bar to 4 bars. The ability to provide an optimal carbon monoxide partial pressure environment to each hydroformylation zone is an advantage of the present invention. When one hydroformylation zone is operated at a higher carbon monoxide partial pressure than the other hydroformylation zone, although not exclusively under those operating conditions, the effluent from the reactor in the hydroformylation zone operating at the higher carbon monoxide partial pressure may be fed to the reactor in the hydroformylation zone operating at the lower carbon monoxide partial pressure. Advantageously, this may increase the efficiency with which the feed stream comprising hydrogen and carbon monoxide is used.

[0038] After the hydroformylation reaction, the aldehyde product stream can be combined for further processing together, or they can be further processed separately. Further processing includes catalyst recovery and separation of aldehyde from unreacted olefins and other impurities using methods known in the art (such as methods described in WO2017 / 158315). The advantage of the present invention is that it is not necessary to use an increased carbon monoxide partial pressure or a downstream process of carbon monoxide stripping gas (such as those disclosed in WO2016 / 089602 and WO2020 / 240194) during catalyst separation to maintain the catalyst stability of the entire process stream. Such processes can be implemented only in the hydroformylation zone where they are needed on a reduced scale, for example, in a zone using an organic monophosphite ligand. After such further processing, N and I isomer separation can then be carried out on each individual aldehyde product stream recovered from each individual hydroformylation zone or on a combined stream. Accordingly, the process may further comprise the steps of feeding each individual aldehyde product stream to a single N and I isomer separation zone and recovering an aldehyde product stream comprising an N:I ratio greater than an N:I ratio R A The high N:I ratio stream of aldehydes and the N:I ratio of aldehydes containing aldehydes less than the N:I ratio R AAlternatively, the method may further comprise the steps of feeding each individual aldehyde product stream into a separate N and I isomer separation zone each comprising an isomer tower, and recovering a high N:I ratio stream and a low N:I ratio stream from each individual N and I isomer separation zone, the high N:I ratio stream comprising an aldehyde having an N:I ratio greater than the N:I ratio in the aldehyde product stream fed to the zone, and the low N:I ratio stream comprising an aldehyde having an N:I ratio less than the N:I ratio in the stream fed to the zone. The low N:I ratio stream typically has an N:I ratio less than about 1:90, suitably less than about 1:99. The high N:I ratio stream typically has an N:I ratio greater than about 90:1, suitably greater than about 99:1. The N and I isomer separation zone contains one or more separation containers, generally a distillation tower, which is known in the art, for example as described in WO2017 / 182780.

[0039] Commercially important downstream products are alcohols prepared by hydrogenation of aldehydes produced by the inventive method, such as butanols prepared from propylene feed by N-butylaldehyde. Other commercially important downstream products are alkyl alcohols, typically 2-alkyl alkanols, which are prepared by aldol condensation of the positive aldehydes prepared by the inventive method, followed by dehydration and hydrogenation. For example, 2-ethylhexanol is produced by N-butylaldehyde (from propylene feed) and 2-propylheptanol is produced by N-valeraldehyde (from butene feed). Other alkyl alcohols (such as neopentyl glycol) can be prepared using the aldol condensation reaction involving other aldehydes, in the case of neopentyl glycol, the aldehyde is formaldehyde, followed by dehydration and hydrogenation. Isobutyraldehyde is used in the production of neopentyl glycol.

[0040] Accordingly, the present invention also provides a method for preparing alcohol, which comprises the following steps: using the method of the present invention to prepare an alcohol in an N:I ratio R A N and I aldehydes are produced, and at least some of the aldehydes are then hydrogenated to provide alcohols. Before hydrogenation, N and I aldehyde isomer separation can be performed as described above so that a high N:I ratio stream or a low N:I ratio stream is hydrogenated. Alternatively, the aldehyde can be hydrogenated without aldehyde isomer separation. The hydrogenation step can be operated under any suitable conditions, for example as described in WO2019 / 197831.

[0041] The present invention also provides a method for preparing an alkyl alkanol, which is typically a 2-alkyl alkanol, such as 2-ethylhexanol or 2-propylheptanol, and more substituted alkyl alkanols, such as neopentyl glycol. The method comprises the following steps: using the above method to produce high and low N:I ratio streams, then subjecting one of the high or low N:I ratio streams to an aldol condensation reaction, followed by a dehydration and hydrogenation step to provide an alkyl alcohol. Typically, for example, when preparing a 2-alkyl alcohol (such as 2-ethylhexanol or 2-propylheptanol), a high N:I ratio stream, typically having an N:I ratio greater than about 99:1, will be used. In the case of neopentyl glycol, a low N:I ratio stream, typically having an N:I ratio less than about 1:99, will be used.

[0042] Such processing steps are known in the art and may be operated under any suitable conditions, such as aldol condensation and dehydration as described in US5,434,313, US6,340,778 and US9,006,495 and hydrogenation as described in WO2018 / 069714.

[0043] The present invention will now be described by way of example, with reference to the accompanying drawings and the production of I and N butyraldehydes by the hydroformylation of propylene and synthesis gas. It should be understood that it is equally applicable to the production of other aldehydes from suitable alternative olefin feeds. The technician will also understand that the accompanying drawings are illustrative and that other equipment items may be needed in commercial equipment, such as reflux drums, pumps, vacuum pumps, compressors, gas recycle compressors, temperature sensors, pressure relief valves, control valves, flow controllers, level controllers, etc. The provision of such auxiliary equipment items does not constitute a part of the present invention and is in accordance with conventional chemical engineering practice.

[0044] Figure 1 A schematic diagram illustrating the overall concept of the process of the present invention is shown in . The process has two parallel hydroformylation zones, each zone having a different ligand-metal catalyst system. The ligand-metal catalyst system in zone one produces a low N:I aldehyde product ratio (typically about 1:1), while the ligand-metal catalyst system in zone two produces a high N:I aldehyde product ratio (typically about 30:1). Propylene 1 and synthesis gas 2 feeds are each passed through their respective purification systems 3 and 4. After the feed is purified, the feed is split and fed to zone one and zone two in proportion to the required production capacity of each zone. Propylene is split into stream 5A entering zone one and stream 5B entering zone two, and synthesis gas is split into stream 6A entering zone one and stream 6B entering zone two.

[0045] The hydroformylation zone one reactors 7 and 8 (in this case two reactors in series) are operated at temperature and pressure conditions optimized for the first zone ligand-metal catalyst system. The reaction temperatures in zone one reactors 7 and 8 are typically the same, with the pressure in reactor 8 being slightly lower to allow for easy transfer of fluids from reactor 7 to reactor 8. Liquid 7L and vapor 7V streams are typically fed separately from reactor 7 to reactor 8. The hydroformylation zone two reactors 9 and 10 are operated in a similar manner, but are typically operated at different temperature and pressure conditions than zone one, which are optimized for the second ligand-metal catalyst system.

[0046] Propylene and synthesis gas feeds pass through the reactors in two hydroformylation zones. Some of the synthesis gas feeds can bypass the first reactor (streams 6C and 6D) in each zone and feed the second reactor. The exhaust gases from the second reactor streams 8V and 10V are each cooled in a corresponding exhaust condenser 11 or 12 to maximize the recovery of the butyraldehyde product, and the exhaust gas streams 11V and 12V are removed from the system to limit the accumulation of inert substances. Then the crude reactor product streams 8L and 11L from the hydroformylation zone one enter the zone one product recovery system 13. Here, butyraldehyde is evaporated and condensed under optimal conditions to separate it from the catalyst, and the concentrated catalyst solution stream 15 is recycled back to the zone one reactors 7 and 8. Typically, as disclosed in WO2016 / 089602 and WO2020 / 240194, an increased carbon monoxide partial pressure or carbon monoxide stripping gas will be used during the catalyst separation in this zone.

[0047] In a similar manner, the crude reactor product from zones two 10L and 12L is passed to zone two product recovery system 14 where the butyraldehyde is vaporized and condensed to separate it from the catalyst and a concentrated catalyst solution stream 16 is recycled back to the zone 2 reactor. Advantageously, no increased carbon monoxide partial pressure or carbon monoxide stripping gas will be required in this zone, thereby reducing the overall equipment required and associated expenses compared to processes using multiple ligand-metal catalysts in the same zone to produce aldehydes having similar N:I ratios in a single reaction zone.

[0048] The crude butyraldehyde products from hydroformylation zone one stream 17 and hydroformylation zone two stream 18 may then be combined and passed to a stabilizer column 19 equipped with an associated reboiler and condenser. Here, light components such as propylene, propane, and any dissolved gases are removed in an overhead stream 21 before the crude butyraldehyde stream 20 is passed to an isomerization column 22 equipped with an associated reboiler and condenser. The isomerization column separates the crude butyraldehyde into N butyraldehyde stream 23 and I butyraldehyde stream 24 products.

[0049] exist Figure 2In the embodiment of the present invention, the exhaust gas stream 11V rich in synthesis gas enters the reactor of zone 2 from zone 1 via reactor 9. Accordingly, some of the hydrogen and carbon monoxide in the residual hydrogen and carbon monoxide can be used for hydroformylation synthesis in zone 2. In this case, zone 1 needs to be operated at a slightly higher pressure than zone 2. Such use of the exhaust gas can improve the efficiency of the use of the stream containing hydrogen and carbon monoxide.

[0050] Example

[0051] Low and high N:I ratio flowsheets and mixed ligand comparative examples reflecting the process disclosed in WO2008 / 115740 were independently tested using a small-scale plant with three hydroformylation reactors in continuous operation. Each reactor had an independent syngas supply and effluent, allowing single or multiple reactor testing. The unit was also equipped with product separation and catalyst recovery to allow long-term continuous testing.

[0052] After being dissolved in butyraldehyde or another suitable solvent (e.g., toluene, Texanol), the catalyst solution is introduced into the reactor system. Synthesis gas and propylene are then introduced to start continuous operation. Process parameters are adjusted to optimize temperature, pressure, ligand-metal catalyst concentration and output. Various analytical techniques known to the technician are used to determine the composition of all gas and liquid streams. All analysis and field equipment are verified by regular equipment calibration or inspection. Then, this data is used to determine the selectivity information about the process. As described above, the embodiments are performed using the optimized conditions for this individual catalyst system.

[0053] Comparative example of mixed ligand system

[0054] The reactor was charged with rhodium metal and an organomonophosphite ligand (ligand A) and an organodiphosphite ligand (ligand B). The system was run for a total of 140 days under conditions optimized primarily for ligand B, with a desired N:I ratio of 3. The reactor system was operated at a mixed butyraldehyde production rate of 3.0 gmol / h, and the desired N:I ratio of butyraldehyde was obtained in two different operating stages (0-70 days and 120-130 days). The reduction in rhodium concentration in these two stages was 0.151 μg lost Rh / g butyraldehyde produced during these two periods, as measured by ICP. The change in rhodium concentration over time is shown in Figure 2. Figure 3 shown.

[0055] Parallel Zone Example

[0056] The hydroformylation of propylene to butyraldehyde is carried out in two separate reaction zones, a low N:I zone and a high N:I zone, with a desired N:I ratio of 3. The desired N:I ratios in each zone and the required capacity in each zone are shown in Table 1 below.

[0057]

[0058] *bal=Butyraldehyde

[0059] Table 1

[0060] Low N:I Zone

[0061] The reactor was charged with rhodium metal and an organomonophosphite ligand (ligand A). The system was run for a total of 100 days under conditions optimized for ligand A. In this example, the N:I ratio was kept constant at about 1.4. The reduction in rhodium concentration measured by ICP was 0.073 μg Rh lost / g butyraldehyde produced. The change in rhodium concentration over time is shown in Figure 2. Figure 4 shown.

[0062] High N:I Zone

[0063] The reactor was charged with rhodium metal and an organic diphosphite ligand (ligand B). The system was run for 90 days under conditions optimized primarily for ligand B. In this example, the N:I was maintained at about 30:1. The reduction in rhodium concentration measured by ICP was 0.002 μg Rh lost / g butyraldehyde produced. The change in rhodium concentration over time is shown in Figure 2. Figure 5 shown.

[0064] in conclusion

[0065] By using the parallel hydroformylation zones with the N:I and relative capacities shown in Table 1 above, the mixed ligand system would have an expected Rh loss of 0.151 μg lost Rh / g butyraldehyde produced (Comparative Example), while the combined parallel zone system would have an expected Rh loss of 0.042 μg lost Rh / g butyraldehyde produced.

Claims

1. A process for the hydroformylation of olefins in a ratio R A A process for producing normal (N) and iso (I) aldehydes comprising hydroformylating an olefin with hydrogen and carbon monoxide in the presence of a ligand-metal catalyst; wherein the hydroformylation is carried out in at least two separate parallel hydroformylation zones, each hydroformylation zone comprising one or more hydroformylation reactors connected in series; and Each individual hydroformylation zone produces N and I aldehydes at a different N:I ratio than the other hydroformylation zones; The method comprises the following steps: i) supplying an olefin feed stream to each individual hydroformylation zone; ii) supplying a stream comprising hydrogen and carbon monoxide to each individual hydroformylation zone; iii) recovering an aldehyde product stream from each individual hydroformylation zone; Wherein the N:I ratio R A is the total N:I ratio contained in the aldehyde product stream.

2. The method of claim 1, wherein the N:I ratio R A Less than about 10:

1.

3. The method according to claim 1 or claim 2, wherein the N:I ratio R A is at least about 0.5:

1.

4. A process according to any preceding claim, wherein the hydroformylation is carried out in two separate parallel hydroformylation zones.

5. A process according to any preceding claim wherein one hydroformylation zone is operated under conditions to produce an aldehyde product stream having an N:I ratio of about 2:1 or less.

6. The process of claim 5 wherein the hydroformylation zone operated under conditions to produce an aldehyde product stream having an N:I ratio of about 2:1 or less comprises a ligand-metal catalyst in which the ligand is an organomonophosphite ligand.

7. A process according to any preceding claim wherein one hydroformylation zone is operated under conditions to produce an aldehyde product stream having an N:I ratio of at least about 6:

1.

8. The process of claim 7 wherein the hydroformylation zone operated under conditions to produce an aldehyde product stream having an N:I ratio of at least about 6:1 comprises a ligand-metal catalyst in which the ligand is an organomonophosphine ligand.

9. The process of claim 7 or claim 8 wherein the hydroformylation zone operated under conditions to produce an aldehyde product stream having an N:I ratio of at least about 6:1 comprises a ligand-metal catalyst in which the ligand is an organopolyphosphite ligand.

10. A process according to any preceding claim in which the effluent from a reactor in a hydroformylation zone operating at a higher carbon monoxide partial pressure is fed to a reactor in a hydroformylation zone operating at a lower carbon monoxide partial pressure.

11. The method according to any preceding claim, further comprising the steps of: Each individual aldehyde product stream is fed to a single N and I isomer separation zone and a aldehyde product stream comprising an N:I ratio greater than an N:I ratio R is recovered. A The high N:I ratio stream of aldehydes and the N:I ratio of aldehydes containing aldehydes less than the N:I ratio R A A low N:I ratio stream of aldehydes.

12. A process for preparing an alkyl alcohol comprising producing high and low N:I ratio streams using the process of claim 11 and then subjecting one of the high or low N:I ratio streams to an aldol condensation reaction followed by a dehydration and hydrogenation step to provide the alkyl alcohol.

13. A process according to any preceding claim, wherein the olefin is propylene and the aldehyde is butyraldehyde.

14. A method for preparing alcohol, comprising the steps of: Using the method according to any one of claims 1 to 11 with an N:I ratio R A N and I aldehydes are produced and at least some of the aldehydes are then hydrogenated to provide the alcohol.

15. The method of claim 14, wherein the alcohol is butanol.

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