Method for producing aldehydes and methods for producing alcohols

Abstract

In a method for producing aldehydes by hydroformylating a starting olefin such as ethylene with an oxogas in the presence of a complex catalyst of a group 8-10 metal with an organophosphorus ligand, the present invention provides a method for producing aldehydes with high productivity by improving the hydroformylation reaction rate while maintaining a high yield of aldehydes. [Solution] In a method for producing aldehydes by hydroformylating an olefin with an oxo gas containing hydrogen and carbon monoxide in the presence of a catalyst, the above problem is solved by controlling the ratio of the olefin content to the unsaturated aldehyde content in the hydroformylation reaction zone to be greater than or equal to a predetermined value a.

Description

Technical Field

[0001] The present invention relates to a method for producing an aldehyde and a method for producing an alcohol.

Background Art

[0002] There is known a method for producing an aldehyde by reacting an olefin with an oxo gas containing hydrogen and carbon monoxide in the presence of a transition metal of Groups 8 to 10 of the long-period periodic table (hereinafter sometimes simply referred to as "Group 8 to 10 metal") - an organophosphorus complex catalyst (hereinafter sometimes simply referred to as "metal complex catalyst") (for example, Patent Document 1). This hydroformylation reaction is also referred to as the "oxo reaction", and the mixed gas of hydrogen (H2) and carbon monoxide (CO) used in the reaction is called "oxo gas".

[0003] As a metal complex catalyst used when producing an aldehyde by subjecting an olefin to a hydroformylation reaction, for example, Patent Document 2 discloses a Group 8 to 10 metal - DBPO complex catalyst using tris(2,4-di-tert-butylphenyl) phosphite (hereinafter sometimes abbreviated as "DBPO") as a ligand from the viewpoint of catalytic activity, and a method for producing an aldehyde by subjecting an olefin to a hydroformylation reaction in the presence of the complex catalyst.

[0004] Further, Patent Document 3 reports a method for producing an aldehyde in which oxygen is supplied to the hydroformylation reaction zone in order to suppress the inhibition of the activity of the hydroformylation reaction catalyst by unsaturated monoaldehydes such as substituted acrolein such as 2-ethylhexenal by-produced during the hydroformylation reaction.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] In the aforementioned Group 8-10 metal-organophosphorus complex catalysts, expensive transition metals such as rhodium are used as the Group 8-10 metals. Therefore, there is a need to improve the hydroformylation reaction rate per unit amount of the metal complex catalyst and reduce the amount of metal complex catalyst used relative to the olefin substrate. However, the method for producing aldehydes described in Patent Document 2 does not mention any method for improving the hydroformylation reaction rate and reducing the amount of expensive metal complex catalysts, particularly organophosphorus ligands, used. Furthermore, in the method for producing aldehydes described in Patent Document 3, the supplied oxygen oxidizes the organophosphorus ligand, deactivating the hydroformylation reaction catalyst. This necessitates the excessive use of expensive organophosphorus ligands, leading to increased manufacturing costs.

[0007] The present invention aims to solve these problems. In other words, the object of the present invention is to provide a method for producing aldehydes by hydroformylating raw material olefins such as ethylene with oxogas in the presence of a hydroformylation catalyst such as a complex catalyst of group 8 to 10 metals with organophosphorus ligands such as DBPO, while maintaining a high yield of aldehydes and improving the hydroformylation reaction rate, thereby producing aldehydes with high productivity. [Means for solving the problem]

[0008] As a result of repeated studies by the present inventors to solve the above problems, the present inventors focused on the fact that unsaturated monoaldehyde produced as a by-product during the hydroformylation reaction inhibits the catalytic activity of hydroformylation reaction catalysts such as complex catalysts of group 8 to 10 metals with organophosphorus ligands such as DBPO. They found that the above problems can be solved by controlling the ratio of the content of raw material olefin to the content of unsaturated monoaldehyde in the hydroformylation reaction zone to a predetermined value or higher, or by keeping the content of unsaturated aldehyde in the hydroformylation reaction solution below a certain value, and thus completed the present invention. In other words, the gist of this invention is as follows:

[0009] [1] A method for producing an aldehyde by hydroformylating an olefin with an oxo gas containing hydrogen and carbon monoxide in the presence of a catalyst, comprising controlling the ratio of the olefin content to the unsaturated aldehyde content in the hydroformylation reaction zone to be greater than or equal to a predetermined value a. [2] The method for producing an aldehyde according to [1], wherein the predetermined value a is 0.95. [3] The method for producing an aldehyde according to [1] or [2], wherein the unsaturated aldehyde comprises a compound (1) represented by the following general formula (I). [ka] (In the above formula (I), R 1 and R 2 Each of these independently represents an alkyl group, alkoxy group, substituted amino group, aryl group, aryloxy group, or heteroaryl group, which may have substituents. [4] A method for producing an aldehyde according to [1] to [3], comprising withdrawing a part or all of the reaction solution containing an unsaturated aldehyde from the hydroformylation reaction zone, reducing the content of the unsaturated aldehyde in the withdrawn reaction solution, and then supplying the reaction solution to the hydroformylation reaction zone. [5] The method for producing an aldehyde according to [1] to [4], wherein the content of the unsaturated aldehyde is reduced by sequentially performing the following steps (a) to (c). Step (a): Transfer part or all of the reaction solution withdrawn from the hydroformylation reaction zone to a separation container. Step (b): Remove some or all of the gas or liquid from the separation container that has a higher concentration of the unsaturated aldehyde than the reaction solution. Step (c): The liquid containing the catalyst is supplied from the separation container to the hydroformylation reaction zone. [6] The method for producing an aldehyde according to [1] to [5], wherein the control is performed by adjusting the gas partial pressure of the olefin in the gas phase of the hydroformylation reactor. [7] A method for producing an aldehyde according to [1] to [6], comprising controlling the control so that the ratio is greater than or equal to a predetermined value a, based on an arbitrary analytical value of the process solution in the hydroformylation reaction zone. [8] The method for producing an aldehyde according to [7], wherein the arbitrary analytical value is the hydroformylation reaction rate calculated from the hydroformylation reaction solution withdrawn from the hydroformylation reactor. [9] A method for producing an aldehyde by hydroformylating an olefin with an oxogas containing hydrogen and carbon monoxide in the presence of a catalyst, A method for producing an aldehyde, wherein the content of unsaturated aldehyde in the hydroformylation reaction solution in the hydroformylation reaction zone is 0.35 mol / L or less. A method for producing aldehydes as described in

[10] [9], (1) A step of supplying the liquid containing the catalyst, the olefin and the oxo gas to a hydroformylation reactor, (2) After step (1), the hydroformylation reactor is operated so that the aldehyde and unsaturated aldehyde are produced in the hydroformylation reactor, (3) After step (2), a step of recovering the reaction solution containing the unsaturated aldehyde from the hydroformylation reactor, including, and, A method for producing an aldehyde, comprising maintaining the content ratio of the unsaturated aldehyde in the reaction liquid recovered in the step (3) at 0.35 mol / L or less by performing at least one of the following steps (1-1) to (3-1). (1-1): A step of controlling the content ratio of the unsaturated aldehyde in the liquid containing the catalyst supplied in the step (1). (2-1): A step of removing part or all of the unsaturated aldehyde generated in the step (2). (3-1): A step of controlling the recovery rate of the reaction liquid in the step (3).

[11] The method for producing an aldehyde according to [1] to

[10] , wherein the catalyst contains a Group 8-10 metal-organophosphorus complex catalyst of the long-period type periodic table.

[12] The method for producing an aldehyde according to [1] to

[11] , wherein the catalyst contains a Group 8-10 metal-phosphite complex catalyst of the long-period type periodic table.

[13] The method for producing an aldehyde according to [1] to

[12] , wherein the catalyst contains a Group 8-10 metal-tris(2,4-di-tert-butylphenyl)phosphite of the long-period type periodic table.

[14] The method for producing an aldehyde according to

[11] to

[13] , wherein the Group 8-10 metal of the long-period type periodic table contains rhodium.

[15] The method for producing an aldehyde according to [1] to

[14] , wherein the olefin contains ethylene, the aldehyde contains propionaldehyde, and the unsaturated aldehyde contains 2-methylpentenal.

[16] A method for producing an alcohol, comprising producing an aldehyde by the method according to [1] to

[15] and producing a corresponding alcohol from the aldehyde. [Effect of the Invention]

[0010] According to the present invention, in a method for producing an aldehyde by subjecting a raw material olefin to a hydroformylation reaction with oxo gas in the presence of a catalyst for the hydroformylation reaction such as a complex catalyst of a Group 8-10 metal having an organic phosphorus such as DBPO as a ligand, it is possible to produce an aldehyde with high productivity while maintaining a high yield of the aldehyde and improving the hydroformylation reaction rate. Thereby, it is possible to produce an aldehyde with high efficiency without increasing the amount of use of an expensive metal complex catalyst, particularly an organic phosphorus ligand.

Brief Description of the Drawings

[0011] [Figure 1] It is a graph showing the relationship between the ethylene / 2MP (2-methylpentenal) ratio in the reaction solution and the hydroformylation reaction rate in Examples and Comparative Examples of Experiment Numbers 2 to 4. [Figure 2] It is a graph showing the relationship between the ethylene / 2MP ratio in the reaction solution and the hydroformylation reaction rate in the Example of Experiment Number 1. [Figure 3] It is a graph showing the relationship between the 2MP concentration in the reaction solution and the hydroformylation reaction rate in Examples 1, 8, 13, and Comparative Example 9 in which the ethylene concentration in the reaction solution is about the same (0.316 to 0.321 mol / L).

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[0013] Unless otherwise specified, the numerical range represented by "~" in this specification means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. "A~B" means A or more and B or less.

[0014] In this specification, "A or B" means "A," "B," and "A and B" unless otherwise specified. For example, "including A or B" means "including A," "including B," and "including A and B" unless otherwise specified.

[0015] In this specification, "mass%" indicates the percentage of a given component contained in 100% of the total amount. Furthermore, "mass%" and "weight%" are synonymous.

[0016] In this specification, "content ratio" and "concentration" are used as synonymous terms. For example, "content ratio of component B in A" or "concentration of component B in A" means the ratio obtained by dividing the content b of component B by the total amount a of A, unless otherwise specified. This ratio is calculated as b / a × 100 (%). Unless otherwise specified, the unit of expression for this ratio is a unit that can be appropriately selected by a person skilled in the art, such as mass percentage, volume percentage, or mole percentage.

[0017] In this specification, “optional” or “optionally” means that the circumstances described below may or may not occur, and therefore the description includes both the cases in which the circumstances occur and the cases in which they do not occur.

[0018] As used herein, the term "approximately" can mean a range of 20% above or below the stated value. For example, a temperature of approximately 75°C relative to 0°C encompasses the range of 60°C to 90°C. All steps described herein may be carried out in any preferred order, unless otherwise specified herein or unless the context clearly contradicts it.

[0019] The first and second embodiments of the present invention's method for producing aldehydes may be collectively referred to as "the present invention's method for producing aldehydes" or "the present invention."

[0020] The catalyst, olefin, oxogas, aldehyde, unsaturated aldehyde, hydroformylation reaction solution, and hydroformylation reactor used in the first and second embodiments of the present invention for producing aldehydes are synonymous between the respective embodiments.

[0021] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0022] <Method for producing aldehydes> (First embodiment) A first embodiment of the present invention's method for producing aldehydes is a method for producing aldehydes by hydroformylating an olefin, described later, with an oxo gas containing hydrogen and carbon monoxide in the presence of a catalyst, wherein the ratio of the olefin content to the unsaturated aldehyde content, described later, in the hydroformylation reaction zone is controlled to be greater than or equal to a predetermined value a. (Second Embodiment) A second embodiment of the present invention's method for producing aldehydes is a method for producing aldehydes by hydroformylating an olefin, described later, with an oxo gas containing hydrogen and carbon monoxide in the presence of a catalyst, wherein the content of unsaturated aldehydes in the hydroformylation reaction solution is 0.35 mol / L or less.

[0023] (First and second embodiments) Here, the aldehyde obtained by the "method for producing aldehydes" in the present invention is an aldehyde obtained directly by a hydroformylation reaction and is different from an unsaturated aldehyde.

[0024] In this specification, the term "hydroformylation reaction zone" refers to the zone including the reactor for carrying out the hydroformylation reaction (also referred to as the "hydroformylation reactor") and surrounding equipment such as a gas-liquid separator attached to the reactor.

[0025] (First embodiment of a method for producing aldehydes) In the first embodiment of the method for producing aldehydes of the present invention, the predetermined value a or greater is the permissible lower limit of the ratio of the olefin content to the unsaturated aldehyde content in the hydroformylation reaction zone. The predetermined value a or greater refers to the lower limit of the ratio of the olefin content to the unsaturated aldehyde content when the hydroformylation reaction rate and aldehyde yield during aldehyde production are within a range that does not impede practical use. This value may be, for example, empirically determined using the aldehyde production apparatus used, or it may be theoretically determined using simulations. In the examples of the present invention, the value used is empirically determined based on the results of a reasonable number of trials using the aldehyde production apparatus used.

[0026] In the first embodiment of the method for producing aldehydes according to the present invention, by controlling the ratio of the olefin content to the unsaturated aldehyde content in the hydroformylation reaction zone to be greater than or equal to a predetermined value a, it is possible to produce aldehydes by hydroformylating an olefin with an oxo gas, while maintaining a high yield of the aldehyde, thereby improving the hydroformylation reaction rate and producing aldehydes with high productivity.

[0027] The lower limit of the predetermined value a is not particularly limited, but from the viewpoint of improving the hydroformylation reaction rate while maintaining a high yield of aldehydes and enabling the production of aldehydes with high productivity, it can be set to 0.95. 1.1 is more preferred, and 1.3 is even more preferred.

[0028] The upper limit of the predetermined value a is not particularly limited, but from the viewpoint of suppressing the increase in manufacturing costs necessary to improve the ratio of the olefin content to the unsaturated aldehyde content, it can usually be 700, 500, 300, 200, or 50. 3.0 is more preferred, 2.4 is even more preferred, 2.2 is particularly preferred, and 1.9 is most preferred. The above upper and lower limits can be combined in any way.

[0029] (Second embodiment of the method for producing aldehydes) In a second embodiment of the present invention's method for producing aldehydes, by setting the content of unsaturated aldehydes in the hydroformylation reaction solution to 0.35 mol / L or less, when producing aldehydes by hydroformylation reaction of olefins with oxogas, the hydroformylation reaction rate can be improved while maintaining a high yield of the aldehydes, thereby enabling the production of aldehydes with high productivity.

[0030] The upper limit of the unsaturated aldehyde content in the hydroformylation reaction solution is 0.35 mol / L or less, preferably 0.30 mol / L or less, more preferably 0.25 mol / L or less, even more preferably 0.20 mol / L or less, even more preferably 0.15 mol / L or less, particularly preferably 0.10 mol / L or less, and most preferably 0.05 mol / L or less, from the viewpoint of improving the hydroformylation reaction rate. On the other hand, the lower limit of the unsaturated aldehyde content is not particularly limited, but from the viewpoint of economics such as the manufacturing costs required for the separation and removal of unsaturated aldehyde in the hydroformylation reaction solution, it is preferably 0.00001 mol / L or more, more preferably 0.00005 mol / L or more, even more preferably 0.0005 mol / L or more, and particularly preferably 0.005 mol / L or more. The upper and lower limits for the proportion of unsaturated aldehydes in the hydroformylation reaction solution can be combined arbitrarily.

[0031] A second embodiment of the method for producing aldehydes according to the present invention may include performing the following steps (1) to (3) in sequence. (1) A step of supplying the liquid containing the catalyst, the olefin, and the oxo gas to a hydroformylation reactor. (2) A step after step (1) above, in which the hydroformylation reactor is operated so that the aldehyde and unsaturated aldehyde are produced in the hydroformylation reactor. (3) A step of recovering the reaction solution containing the unsaturated aldehyde from the hydroformylation reactor after step (2). In the present invention's method for producing aldehydes, the step of operating the hydroformylation reactor means the step of adjusting the reaction conditions such as temperature, pressure, concentration of raw materials and catalysts, and reaction time inside the hydroformylation reactor to allow the hydroformylation reaction to proceed.

[0032] Furthermore, in a second embodiment of the method for producing aldehydes of the present invention, by performing at least one of the following steps (1-1) to (3-1), the content of the unsaturated aldehyde in the reaction solution recovered in step (3) can be maintained at 0.35 mol / L or less. (1-1): A step of controlling the content ratio of the unsaturated aldehyde in the liquid containing the catalyst supplied in step (1) above, (2-1): A step to remove part or all of the unsaturated aldehyde generated in step (2) above. (3-1): A step to control the recovery rate of the reaction solution in step (3) above.

[0033] The specific conditions and methods for steps (1) to (3) and steps (1-1) to (3-1) are not particularly limited and can be appropriately selected by those skilled in the art in accordance with well-known technology. Alternatively, conditions similar to those of the first embodiment of the method for producing aldehydes of the present invention can be used.

[0034] <Unsaturated aldehydes> In the present invention, an unsaturated aldehyde refers to a compound having one or more aldehyde groups in its molecule, and to which the carbon atom to which the aldehyde group is bonded forms a carbon-carbon double bond. The aforementioned unsaturated aldehyde can reduce the hydroformylation reaction rate and decrease the yield of aldehyde when an olefin is hydroformylated with an oxogas to produce an aldehyde. Therefore, by controlling the ratio of the olefin content to the unsaturated aldehyde content in the hydroformylation reaction zone to a predetermined value a or higher, it is possible to maintain a high yield of aldehyde while improving the hydroformylation reaction rate and producing aldehydes with high productivity.

[0035] The unsaturated aldehyde preferably includes compound (1) represented by the following general formula (I). [ka] (In the above formula (I), R 1 and R 2 Each of these independently represents an alkyl group, alkoxy group, substituted amino group, aryl group, aryloxy group, or heteroaryl group, which may have substituents.

[0036] The aforementioned unsaturated aldehyde may be a single type or a mixture of two or more types.

[0037] Specifically, the aforementioned unsaturated aldehyde is an unsaturated aldehyde produced by the hydroformylation reaction of the olefin, in which two aldehyde molecules are subjected to an aldol condensation reaction and a dehydration reaction, and which has one or more aldehyde groups in its molecule, and to which the carbon atoms to which the aldehyde groups are bonded form a carbon-carbon double bond. The aldehyde is not particularly limited, and examples include saturated aldehydes having at least 3 carbon atoms, and usually 3 to 10 carbon atoms. Saturated aldehydes include linear and side-chain aldehydes, specifically propionaldehyde, butyraldehyde, varelualdehyde, heptylaldehyde, nonylaldehyde, etc., with butyraldehyde and varelualdehyde being preferred, and n-butyraldehyde being particularly preferred. Furthermore, the unsaturated aldehydes include the aldol condensation reaction products and their dehydration reaction products corresponding to the aldehyde. More specifically, examples include 2-methylpentenal, 2-ethylhexenal, and 2-propylheptenal, preferably 2-ethylhexenal and 2-propylheptenal, and particularly preferably 2-ethylhexenal (ethylpropyl acrolein). This aldol condensation reaction and dehydration can be carried out by known methods, and are usually carried out by using an alkaline aqueous solution, for example, a 1-5 wt% sodium hydroxide aqueous solution, as a catalyst, and usually by reacting at 80-100°C. These can be used individually or in combination of two or more types.

[0038] The method for controlling the ratio of the olefin content in the hydroformylation reaction zone is not particularly limited, and examples include the following methods (1) to (3). (1) Method for adjusting the gas partial pressure of the raw material olefin in the gas phase of a hydroformylation reactor (2) A method of removing part or all of the gas phase containing the raw material olefin or the liquid phase (reaction solution) containing the raw material olefin from the hydroformylation reactor, adjusting the concentration of the raw material olefin in the removed liquid using a known method, and then recirculating it into the gas phase or liquid phase (reaction solution) of the hydroformylation reactor. (3) Method for adjusting the volume of the gas phase or liquid phase of a hydroformylation reactor

[0039] Among these, method (1) is a method that specifically increases the amount of raw material olefin supplied to the gas phase in a hydroformylation reactor, thereby increasing the gas partial pressure of the raw material olefin and increasing the content of the raw material olefin in the liquid phase. This method is preferred from the viewpoint of excellent operability and operational stability.

[0040] Furthermore, in the first embodiment of the aldehyde production method of the present invention, the olefin content ratio described above can be controlled to be greater than or equal to a predetermined value a, based on any analytical value of the process solution in the hydroformylation reaction zone. By controlling in this manner, it becomes possible to produce aldehydes continuously and stably over a long period of time.

[0041] The arbitrary analytical value of the process liquid is not particularly limited as long as it is related to the hydroformylation reaction rate. For example, the aldehyde content in the reaction liquid after the hydroformylation reaction, which is withdrawn from the reactor, can be used. Information regarding the content of unreacted ethylene and oxo gas in the gas phase of the reactor can also be used as an arbitrary analytical value of the process liquid. This makes it possible to improve the hydroformylation reaction rate more efficiently while maintaining a high yield of aldehyde. As a result, aldehydes can be produced with high productivity while maintaining good catalytic activity of the complex catalyst, without increasing the amount of expensive metal complex catalysts, especially organophosphorus ligands, used.

[0042] Furthermore, in the method for producing aldehydes according to the present invention, a portion or all of the reaction solution containing the unsaturated aldehyde can be withdrawn from the hydroformylation reaction zone, the content of the unsaturated aldehyde in the withdrawn reaction solution can be reduced, and then the reaction solution can be supplied again to the hydroformylation reaction zone, preferably to the hydroformylation reactor.

[0043] In the method for producing aldehydes of the present invention, a specific embodiment for reducing the content of the unsaturated aldehyde is a method in which the following steps (a) to (c) are carried out sequentially. Step (a): Transfer part or all of the reaction solution withdrawn from the hydroformylation reaction zone to a separation container. Step (b): Remove some or all of the gas or liquid from the separation container that has a higher concentration of the unsaturated aldehyde than the reaction solution. Step (c): The liquid containing the catalyst is supplied from the separation container to the hydroformylation reaction zone. The specific conditions and methods for the above-described steps (a) to (c) are not particularly limited and can be appropriately selected by those skilled in the art in accordance with well-known technology.

[0044] Alternatively, another specific embodiment for reducing the unsaturated aldehyde content is a method of vaporizing and separating the components containing unsaturated aldehydes from the extracted reaction solution using a known gas-liquid separation device such as a distillation purification column or stripping apparatus installed within the hydroformylation reaction zone.

[0045] The method described above makes it possible to efficiently reduce the content of unsaturated aldehydes in the hydroformylation reaction zone, particularly in the liquid phase of the hydroformylation reactor.

[0046] Furthermore, before or after reducing the unsaturated aldehyde content in the extracted reaction solution as described above, the reaction solution can be supplied to the hydroformylation reaction zone after undergoing known purification and separation steps such as crystallization or distillation.

[0047] <Catalyst> The catalyst used in this invention is not particularly limited, as long as it has catalytic activity in the hydroformylation reaction of ethylene, but it is preferable that the catalyst includes a long-period metal (hereinafter referred to as "group 8 to 10 metals")-organophosphorus complex catalyst because it exhibits excellent reaction activity in the hydroformylation reaction. As the aforementioned Group 8-10 metal-organophosphorus complex catalyst, for example, the Group 8-10 metal-organophosphorus complex catalyst disclosed in International Publication No. 2023 / 095907 can be used.

[0048] Furthermore, the catalyst in the present invention may include a group 8-10 metal-phosphite complex catalyst, in order to improve the hydroformylation reaction rate and produce aldehydes with high productivity while maintaining good catalytic activity of the complex catalyst and maintaining a high yield of aldehydes, without increasing the amount of expensive metal complex catalysts, particularly organophosphorus ligands used. As the aforementioned Group 8-10 metal-phosphite complex catalyst, for example, the Group 8-10 metal-phosphite complex catalyst disclosed in International Publication No. 2023 / 095907 can be used.

[0049] The catalyst in the present invention may include a group 8-10 metal-DBPO complex catalyst, in which tris(2,4-di-tert-butylphenyl) phosphite (also referred to herein as "DBPO") is used as the organophosphorus ligand, from the viewpoint of producing aldehydes with high productivity while maintaining good catalytic activity of the complex catalyst without increasing the amount of expensive metal complex catalysts, particularly organophosphorus ligands used. In this case, the Group 8-10 metal-organophosphorus complex catalyst may be any complex catalyst that uses DBPO as a ligand, and the ligand of the complex catalyst may be DBPO alone, or DBPO may be used in combination with other compounds. Other ligands used with DBPO are not particularly limited and include cyclohexyldiphenylphosphine and tri-p-tolylphosphine. However, in order to obtain the effects according to the present invention more effectively, it is preferable to use only DBPO as the ligand for the complex catalyst.

[0050] Furthermore, in the method for producing aldehydes according to the present invention, the Group 8 to 10 metals are metals belonging to Groups 8 to 10 of the long-period periodic table. Among these, ruthenium, cobalt, rhodium, palladium, and platinum are preferred because they have high activity when used as catalysts, and rhodium is particularly preferred due to its high activity.

[0051] Furthermore, when the Group 8-10 metal is rhodium (Rh), examples of starting compounds that serve as a source of Rh for the Group 8-10 metal-organophosphorus complex catalyst include one or more of the following: rhodium acetate [Rh(OAc)3], acetylacetonate dicarbonyl rhodium [Rh(AcAc)(CO)2], acetylacetonate carbonyltriphenylphosphine rhodium [Rh(AcAc)(CO)(TPP)], and hydride carbonyl tri(triphenylphosphine) rhodium [HRh(CO)(TPP)3]. Among these, starting compounds that do not have phosphine or phosphite ligands, such as rhodium acetate [Rh(OAc)3] and acetylacetonate dicarbonyl rhodium [Rh(AcAc)(CO)2], are preferred because the effects of DBPO can be utilized when they are reacted with DBPO to form an Rh complex catalyst.

[0052] When the group 8-10 metal is rhodium (Rh) and the ligand is DBPO, DBPO and the aforementioned starting compound (Rh source) may be mixed beforehand and then supplied to the reactor, or DBPO and the aforementioned starting compound may be supplied to the reactor separately. From these supplied compounds, a complex catalyst such as RhH(CO)(DBPO) is formed in the reactor. Furthermore, in the presence of this catalyst, the starting olefin, H2 and CO are supplied to the reactor to carry out a hydroformylation reaction, thereby generating an aldehyde.

[0053] <Hydroformylation reaction> The hydroformylation reaction is carried out by reacting the starting olefin with hydrogen and carbon monoxide in the presence of a catalyst such as a long-period metal-organophosphorus complex.

[0054] (olefin) The raw material olefin of the present invention is usually a linear or branched α-olefin or internal olefin, preferably an olefin having 2 to 8 carbon atoms, specifically including ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-dodecene, 1-tetradecene, etc., and more preferably ethylene, propylene, or 1-butene. Ethylene is a particularly preferred olefin.

[0055] One specific embodiment of the present invention's method for producing an aldehyde is a form in which the olefin contains ethylene, the aldehyde contains propionaldehyde, and the unsaturated aldehyde contains 2-methylpentenal. Alternatively, another specific embodiment of the present invention's method for producing an aldehyde is a form in which the olefin contains propylene, the aldehyde contains n-butyraldehyde or isobutyraldehyde, and the unsaturated aldehyde contains 2-ethylpentenal.

[0056] As the reaction medium for the hydroformylation reaction, a solvent is preferred that dissolves the starting material ethylene and a catalyst such as a group 8-10 metal-organophosphorus complex catalyst, has a higher boiling point than the resulting aldehyde, and does not inhibit the reaction. Examples of solvents that can be used in the hydroformylation reaction include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane and octane; esters such as butyl acetate and butyl butyrate; or ketones.

[0057] In this invention, H2 and CO, used as components of the oxo gas, may be supplied to the reactor separately, or they may be supplied to the reactor together as a pre-mixed oxo gas. For example, gas generated by a reformer or other means may be used, or H2 and CO may be separated from these gases and supplied to the reactor.

[0058] In this invention, the lower limit of the H2 / CO molar ratio of the oxo gas in the reactor is not particularly limited, but from the viewpoint of improving the hydroformylation reaction rate, the H2 / CO molar ratio is preferably 1.0 or higher, more preferably 1.1 or higher, even more preferably 1.5 or higher, and particularly preferably 2 or higher. On the other hand, the upper limit of the H2 / CO molar ratio is not particularly limited, but if it is too high, the hydrogenation reaction to the olefin will proceed and alkanes will be formed, resulting in a decrease in the selectivity of the target product. Therefore, the H2 / CO molar ratio is preferably 8 or lower, more preferably 6 or lower, and even more preferably 4 or lower. The above upper and lower limits can be combined arbitrarily.

[0059] Furthermore, oxo gas may contain substances other than H2 and CO. While there are no particular limitations on the substances that may be present, examples include nitrogen, and its amount should be around 1%.

[0060] The amount of oxogas supplied is not particularly limited as long as it is sufficient to convert the raw material olefin into an aldehyde in the hydroformylation reaction. For example, in a fully mixed reactor, 2.1 tons / hour may be supplied for every 1 ton / hour of raw material olefin fed to the reactor.

[0061] In the present invention, the amount of catalyst used in the hydroformylation reaction is approximately 0.1 to 50 ppm by weight in terms of Rh concentration in the hydroformylation reaction solution, and the reaction can also be carried out at a low Rh concentration of 0.5 to 1 ppm by weight. Furthermore, the DBPO concentration is usually 10 to 500 mol / mol, preferably 25 to 300 mol / mol, and particularly preferably 50 to 250 mol / mol relative to Rh.

[0062] Normally, if the amount of catalyst used is insufficient, the reaction will not proceed. Therefore, in conventional methods, the Rh concentration in such a hydroformylation reaction solution was typically around 100-200 ppm by weight, and the ligand concentration was typically 10-500 mol / mol relative to Rh, preferably 25-300 mol / mol, and particularly preferably 50-250 mol / mol. However, in the present invention, by increasing the H2 / CO molar ratio of the oxo gas in the reactor to more than 1, the hydroformylation reaction is accelerated, allowing the amount of catalyst to be reduced to, for example, 0.1-50 ppm by weight, which is about 1 / 2000 to 1 / 2 of the conventional method in terms of Rh concentration. Furthermore, reducing the Rh concentration also reduces the ligand concentration, and because the amount of Rh complex catalyst and ligand is significantly smaller compared to conventional methods, the post-reaction Rh recovery process can be eliminated.

[0063] According to the present invention, even without recovering, regenerating, and reusing the catalyst through an Rh recovery process, the amount of catalyst used is significantly reduced, thus virtually eliminating the disadvantages caused by catalyst loss.

[0064] The temperature of the hydroformylation reaction is usually 20°C or higher, preferably 40°C or higher, more preferably 50°C or higher, and usually 300°C or lower, preferably 200°C or lower, more preferably 150°C or lower. If the reaction temperature is too low, the hydroformylation reaction rate will be slow and the reaction will not proceed sufficiently, and if the reaction temperature is too high, the formation of by-products will be promoted and the catalyst may be deactivated.

[0065] The pressure for the hydroformylation reaction is typically 0.0001 MPaG or higher, preferably 0.01 MPaG or higher, more preferably 0.2 MPaG or higher, and typically 50 MPaG or lower, preferably 30 MPaG or lower, more preferably 20 MPaG or lower. If the reaction pressure is too low, the hydroformylation reaction rate will be slow and the reaction will not proceed sufficiently, and if the reaction pressure is too high, the design pressure of equipment such as reactors will be high, increasing the burden on the equipment.

[0066] Furthermore, since H2 and CO in the reactor are consumed as the reaction progresses, in this invention, H2 and / or CO are supplied as needed so that the gas phase in the reactor always maintains the aforementioned H2 / CO molar ratio during the reaction.

[0067] The reaction time for the hydroformylation reaction is usually 1 minute or more, preferably 10 minutes or more, more preferably 20 minutes or more, and usually 24 hours or less, preferably 10 hours or less, more preferably 5 hours or less. If the reaction time is too short, the reaction will not proceed sufficiently, and if it is too long, the formation of high-boiling point substances will proceed. In the present invention, in order to obtain the effects of the present invention more effectively, it is preferable to keep the H2 / CO molar ratio of the oxo gas in the reactor greater than 1 for 10% or more of the reaction time, preferably 30% or more, more preferably 50% or more, even more preferably 80%, and particularly preferably 90% or more.

[0068] Hydroformylation reactions are typically carried out in the presence of a solvent that is inert to both the starting olefin and the aldehyde produced in the reaction. Suitable solvents for hydroformylation reactions include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane and octane; alicyclic hydrocarbons such as cyclohexane; alcohols such as butanol, octanol, and polyethylene glycol; ethers such as triglime; and esters such as dioctyl phthalate. Furthermore, the aldehyde produced in the reaction, or aldehyde condensates such as trimers and tetramers, can also be used. Additionally, paraffins having the same number of carbon atoms as the starting olefin can be used. For example, in the hydroformylation of propylene, it is preferable to use a mixture of toluene, butyraldehyde, or aldehyde condensates such as trimers and tetramers.

[0069] The type of reactor used in the hydroformylation reaction is not particularly limited, and tank reactors, bubble column reactors, tray column reactors, tubular reactors, or gas stripping reactors can be used. Among these reactors, tank reactors are preferred from the viewpoint of easy control of the ethylene gas partial pressure and oxo gas partial pressure within the reactor. Examples of stirred-tank type reactors include fully mixed reactors and batch reactors. From the viewpoint of easily controlling the partial pressure of ethylene gas and oxo gas within the reactor, a continuous, fully mixed reactor is preferred. When using a fully mixed reactor or a batch reactor, the raw materials, ethylene, oxo gas, and catalyst liquid, are continuously supplied into the reactor to carry out the hydroformylation reaction described above. Furthermore, in order to maintain a constant temperature inside the reactor, the reactor may have internal coils, jackets, external heat exchangers, and the like.

[0070] The reaction solution containing the aldehyde produced in the hydroformylation reaction is removed from the reactor. The separation of the aldehyde product from the reaction solution withdrawn from the reactor can be carried out using any separation operation and apparatus, such as distillation, evaporation, gas stripping, gas absorption, or extraction. Among these, separation by distillation is preferred, in which case the aldehyde product, mainly composed of the aldehyde product, can be separated by distillation from the top of a distillation column. The conditions for distillation are not particularly limited, but it is generally preferable that the column bottom temperature be 50 to 150°C. The pressure inside the column is also not particularly limited, but it is generally preferable that it be 0.01 to 0.1 MPa.

[0071] In this aldehyde separation step, optional means and apparatus for recovering unreacted olefins from the reaction solution may be added. In such cases, a countercurrent contact column or the like is preferably used. Gas-liquid separators or the like may be provided between each apparatus as appropriate.

[0072] As described above, the catalyst solution, which is the residue obtained by separating the aldehyde product from the reaction solution, has conventionally been partially discharged from the reaction system, either continuously or intermittently, to avoid the accumulation of high-boiling point by-products, with the remainder being sent to the catalyst recovery process. However, in the present invention, this residue can also be disposed of by disposing of it directly from the system.

[0073] <Mechanism> According to the first embodiment of the method for producing aldehydes of the present invention, by controlling the ratio of the olefin content to the unsaturated aldehyde content to be greater than or equal to a predetermined value a, the yield of aldehydes can be maintained at a high yield while improving the hydroformylation reaction rate, thereby enabling the production of aldehydes with high productivity. Alternatively, according to a second embodiment of the method for producing aldehydes of the present invention, by setting the content of unsaturated aldehydes in the hydroformylation reaction solution to 0.35 mol / L or less, the hydroformylation reaction rate can be improved while maintaining a high yield of aldehydes, thereby enabling the production of aldehydes with high productivity. Although the reason is unclear, unsaturated aldehydes coordinate to the hydroformyl reaction catalyst via the carbon-carbon double bond and carbon-oxygen double bond structural units (-C=C- and -C=O) contained in the aldehyde structure. By coordinating at a bidentate, the rate of the elementary reaction in which the catalyst inserts into the carbon-carbon double bond is slowed, and the overall hydroformylation reaction rate decreases. It is presumed that by reducing the content of unsaturated aldehydes in the raw material olefin, the exchange reaction between the raw material olefin and the unsaturated aldehyde is promoted, the catalytic activity of the hydroformyl reaction catalyst can be well maintained, and the hydroformylation reaction rate can be improved.

[0074] <Method for producing alcohol> The present invention provides a method for producing alcohol, which involves producing an aldehyde by the present invention's method for producing aldehydes, and then producing a corresponding alcohol from the aldehyde. The method for producing the alcohol corresponding to the aldehyde is not particularly limited and can be carried out according to conventional methods. For example, the alcohol can be produced by subjecting the aldehyde obtained by the method for producing the aldehyde of the present invention to a known hydrogenation reaction as is, according to the method described in Japanese Patent Application Publication No. 2001-10999, or by dimerizing the obtained aldehyde and then subjecting it to a known hydrogenation reaction. Specifically, when the olefin is ethylene, the ethylene can be hydroformylated to obtain propionaldehyde, and then the obtained propionaldehyde can be hydrogenated in the presence of a hydrogenation catalyst and hydrogen to produce propanol. The hydrogenation catalyst used in the hydrogenation reaction can be a known solid catalyst in which a metal such as Ru, Ni, Cr, or Cu is supported on a carrier, and a Ru-based catalyst is preferred. The conditions for the hydrogenation reaction described above are typically a temperature of 60 to 200°C and a hydrogen pressure of approximately 0.1 to 20 MPaG. [Examples]

[0075] The present invention will be described more specifically below with reference to examples. However, the present invention is not limited to these examples. The following reference examples are for illustrative purposes only and are not intended to limit any of the embodiments described herein. The following reference examples do not limit the present invention in any way. The various manufacturing conditions and evaluation results in the following reference experimental examples represent preferred upper or lower limits in embodiments of the present invention. The preferred range may be defined by a combination of the aforementioned upper or lower limits and the values ​​in the following examples or between examples.

[0076] [Raw materials used] The compounds used in the examples and comparative examples are as follows: DBPO: Tris(2,4-di-tert-butylphenyl) phosphite (trade name, manufactured by Tokyo Chemical Industry Co., Ltd.) Rhodium acetate (product name: Rhodium Acetate “BRAUN”, manufactured by Degussa) Ethylene (Trade name: Ethylene, manufactured by Taiyo Nippon Sanso Corporation) Propionaldehyde (Trade name: Propionaldehyde, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Toluene (product name: Toluene, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Methanol (product name: Methanol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) n-Octane (Trade name: Octane, manufactured by Fujifilm Wako Pure Chemical Corporation) 2-Methylpentenal (Trade name: trans-2-Methylpentenal, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0077] [Experiment Number 1: Examples 1-7] <Preparation of the mixed solution> Under a nitrogen gas atmosphere, a stirring bar was placed in a 50 mL stainless steel pressure vessel (hereinafter referred to as "reactor 1"), which had been dried internally. 68.6 mg (0.245 mmol) of rhodium acetate as a group 8-10 transition metal compound and 2.01 g (3.104 mmol) of DBPO as an organophosphorus ligand compound were added. Further, 25.6 g of toluene and 3.85 g of methanol were added as organic solvents, and the mixture was stirred for 5 minutes to dissolve the catalyst and ligand, thereby preparing a catalyst mixture.

[0078] <Precarbonation treatment (activation treatment of catalyst mixture)> Next, oxo gas (hydrogen / carbon monoxide = 1 (molar ratio)) was injected into the liquid phase (catalyst mixture) in reactor 1 under pressure so that the supply pressure of the gas into reactor 1 was 1.5 MPaG. After that, reactor 1 was sealed and the heating was started. After the temperature of the catalyst mixture in reactor 1 reached 100°C, it was stirred for another hour to activate the catalyst mixture. After stirring, the temperature of the liquid in reactor 1 was cooled to room temperature (25°C), and the oxo gas in reactor 1 was depressurized.

[0079] <Hydroformylation reaction> In a nitrogen gas atmosphere, 0.138 g of a precarbonylation-treated catalyst mixture (Rh 0.114 mg, DBPO 9.09 mg), 17.7 mg of DBPO were weighed into a 250 mL stainless steel pressure-resistant container with a stirrer (hereinafter referred to as "Reactor 2") whose interior was dried. 2.78 g of n-octane was added as an internal standard substance, and 65.6 g of propionaldehyde was added as an organic solvent to form a reaction solution. After supplying 1.5 g of ethylene into Reactor 2, the temperature increase was started. When the temperature of the reaction solution reached 90 °C, the total pressure in Reactor 2 was 0.6 MPaG. Next, oxo gas (hydrogen / carbon monoxide = 1 (molar ratio)) was pressured into the liquid phase (reaction solution) in Reactor 2 so that the supply pressure of the gas became 1.5 MPaG, and then the pressure and the temperature of the reaction solution were maintained at 90 °C, and the hydroformylation reaction was carried out for 120 minutes. In addition, the oxo gas consumed in the hydroformylation reaction was automatically replenished from the accumulator into the reactor through a secondary pressure regulator, and the reaction was carried out so that the pressure in the reactor was always maintained at 1.5 MPaG. The partial pressure of ethylene gas in the reactor was calculated as the difference (P2 - P1 = 0.26 MPaA) between the total pressure (P2: 0.70 MPa) in the reactor before the oxo gas was pressured in and the total pressure (P1: 0.44 MPa) of the partial pressure of nitrogen gas (0.09 MPaA) in the reactor and the vapor pressure of propionaldehyde (0.35 MPaA) obtained from Antoine's equation when the temperature of the reaction solution was maintained at 90 °C.

[0080] (Ethylene conversion rate) After the hydroformylation reaction, using gas chromatography, according to the following GC measurement conditions 1, the content ratio of ethylene in the gas phase part and the liquid phase part in Reactor 2 was determined, and the amount of substance of ethylene remaining in the gas phase part and the liquid phase part after the reaction was calculated. Furthermore, the amount of substance of ethylene consumed was calculated from the decrease amount of oxo gas before and after the hydroformylation reaction.

[0081] <GC measurement conditions 1> GC device: GC-2014 (high-performance general-purpose gas chromatograph, manufactured by Shimadzu Corporation) Detector: Flame ionization detector (FID) Carrier gas: Nitrogen gas (column flow rate 2.53 ml / min) Column: Capillary column GS-GasPro (manufactured by Agilent Technologies, size: 30m length x 0.32mm inner diameter) Temperature (heating conditions): 40°C (holding time 5 minutes) → heating at 15°C / min → 240°C (holding time 5 minutes) Inlet temperature: 250℃ Detector temperature: 300℃ Sample volume: 0.3 mL for gas phase samples, 0.5 μL for liquid phase samples (split ratio: 1 / 10)

[0082] Next, the ethylene conversion rate calculated using the following formula (1) was 98.80%.

[0083]

number

[0084] (Ethane selectivity) Furthermore, after the hydroformylation reaction was completed, gas chromatography was used to determine the proportion of ethane in the gas phase and liquid phase of the reactor according to the GC measurement conditions 1 described above, and the amount of ethane remaining in the gas phase and liquid phase after the reaction was calculated.

[0085] Next, the ethane selectivity calculated using the following formula (2) was 0.19%. Ethane selectivity is an indicator of the proportion of ethane produced as a by-product (impurity) during the hydroformylation reaction of ethylene. The smaller this value, the fewer impurities are in the ethylene product.

[0086]

number

[0087] Furthermore, the propionaldehyde selectivity calculated using formula (3) below was 99.81%, and the propionaldehyde yield calculated using formula (4) below was 98.61%.

number

number

[0088] (Hydroformylation reaction rate) Furthermore, the time-dependent change in the ethylene conversion rate was calculated from the time-dependent change in the decrease in oxogas during the hydroformylation reaction. Next, the ethylene consumption per unit time was calculated, and the unit liquid volume in the reactor and the ethylene consumption per unit time were defined as the hydroformylation reaction rate. Furthermore, the time-dependent change in ethylene partial pressure within the reactor was calculated from the time-dependent change in the ethylene conversion rate. Furthermore, using Henry's Law as the basis for calculating the ethylene concentration in the reaction solution, with Henry's constant (which indicates the solubility of ethylene in propionaldehyde at a reaction temperature of 90°C) set to 11.24 MPaA.

[0089] Furthermore, the concentration of 2-methylpentenal (hereinafter sometimes referred to as "2MP") in the reaction solution was measured using gas chromatography according to the GC measurement conditions 2 described below, both before and during the hydroformylation reaction. As a result, the rate of change of the concentration of 2-methylpentenal in the reaction solution was found to be almost constant with respect to the reaction time, both before and during the hydroformylation reaction. Therefore, it was assumed that the concentration of 2-methylpentenal during the hydroformylation reaction can be approximated by a linear equation with respect to the reaction time.

[0090] During the hydroformylation reaction, the ethylene gas partial pressure in the gas phase part of the reactor was calculated from the ethylene conversion rate measured over time, and from that value, the concentrations of ethylene and 2MP in the reaction solution, as well as the ratio of the ethylene concentration to the 2MP concentration (hereinafter referred to as the "ethylene / 2MP ratio"), and the hydroformylation reaction rate were calculated over time. The results measured over time were taken as Examples 1 to 7 and are shown in Table 1. <GC measurement conditions 2> GC apparatus: GC-2025 (high-performance general-purpose gas chromatograph, manufactured by Shimadzu Corporation) Detector: Flame ionization detector (FID) Carrier gas: Nitrogen gas (column flow rate 14.49 ml / min) Column: Capillary column DB-1701 (manufactured by Agilent Technologies, size: length 30 m × inner diameter 0.53 mm, film thickness 1.00 μm) Temperature (temperature increase conditions): 60°C → increasing temperature at 4°C / min → 280°C (holding time 20 minutes) Inlet temperature: 280°C Detector temperature: 280°C Sample volume: 0.4 μL (split ratio: 1 / 9)

[0091] [Experiment No. 2: Examples 8 to 12, Comparative Examples 1 to 4] The precarbonylation treatment was carried out in the same manner as in Example 1 to obtain an activated catalyst mixture solution. Under a nitrogen gas atmosphere, 0.143 g of the catalyst mixture solution (Rh 0.113 mg, DBPO 8.96 mg), 27.7 mg of DBPO were weighed into a 250 mL stainless steel pressure-resistant container with a stirrer whose interior was dried, 0.82 g of 2-methylpentenal, 2.81 g of n-octane as an internal standard substance, and 66.6 g of propionaldehyde as an organic solvent were added to form a reaction solution. After supplying 1.5 g of ethylene into the reactor, it was press-fitted into the liquid phase (reaction solution) in the reactor so that the supply pressure of the oxo gas into the reactor became 2.0 MPaG, and the hydroformylation reaction was carried out for 120 minutes in the same manner as in Example 1 except for maintaining this pressure. Table 1 shows the ethylene conversion rate, ethane selectivity, propionaldehyde selectivity, and propionaldehyde yield, which were measured using the same method as in Example 1.

[0092] Furthermore, using the same method as in Example 1, the time-dependent ethylene gas partial pressure during the hydroformylation reaction, the concentrations of ethylene and 2MP in the reaction solution, the ethylene / 2MP ratio, and the hydroformylation reaction rate were measured and the results are shown in Table 1 as Examples 8-12 and Comparative Examples 1-4.

[0093] [Experiment Number 3: Examples 13-17, Comparative Examples 5-8] A precarbonation treatment was performed using the same procedure as in Example 1 to obtain an activated catalyst mixture. Under a nitrogen gas atmosphere, 0.131 g (0.104 mg Rh, 8.21 mg DBPO) and 17.5 mg DBPO were weighed into a 250 mL stainless steel pressure vessel with a stirrer, which had been dried inside. 1.28 g of 2-methylpentenal, 2.88 g of n-octane as an internal standard, and 59.9 g of propionaldehyde as an organic solvent were added. After supplying 1.5 g of ethylene into the reactor, the oxo gas supply pressure into the reactor was increased to 2.0 MPaG before being injected into the liquid phase (reaction solution) inside the reactor. The hydroformylation reaction was carried out for 180 minutes in the same manner as in Example 1, except that this pressure was maintained.

[0094] The ethylene conversion rate, ethane selectivity, propionaldehyde selectivity, and propionaldehyde yield, measured using the same method as in Example 1, are shown in Table 1.

[0095] Furthermore, using the same method as in Example 1, the time-dependent ethylene gas partial pressure during the hydroformylation reaction, the concentrations of ethylene and 2MP in the reaction solution, the ethylene / 2MP ratio, and the hydroformylation reaction rate were measured and the results are presented in Table 1 as Examples 13-17 and Comparative Examples 5-8.

[0096] [Experiment No. 4: Comparative Examples 9-18] A precarbonation treatment was performed using the same procedure as in Example 1 to obtain a catalyst mixture. Under a nitrogen gas atmosphere, 0.136 g (Rh 0.108 mg, DBPO 8.52 mg) and 16.6 mg of DBPO were weighed into a 250 mL stainless steel pressure vessel with a stirrer, which had been dried inside. 3.25 g of 2-methylpentenal, 2.83 g of n-octane as an internal standard, and 56.7 g of propionaldehyde as an organic solvent were added to form the reaction solution. After supplying 1.4 g of ethylene to the reactor, the oxo gas supply pressure into the reactor was increased to 2.0 MPaG before being injected into the liquid phase (reaction solution) inside the reactor. The hydroformylation reaction was carried out for 180 minutes in the same manner as in Example 1, except that the pressure was maintained.

[0097] Table 1 shows the ethylene conversion rate, ethane selectivity (%), propionaldehyde selectivity, and propionaldehyde yield, which were measured using the same method as in Example 1.

[0098] Furthermore, using the same method as in Example 1, the time-dependent ethylene gas partial pressure during the hydroformylation reaction, the concentrations of ethylene and 2MP in the reaction solution, the ethylene / 2MP ratio, and the hydroformylation reaction rate were measured and the results are shown in Table 1 as Comparative Examples 9 to 18.

[0099] [Table 1]

[0100] Table 1 shows that the yield of propionaldehyde was good in all of experiments 1 to 4.

[0101] In the examples and comparative examples numbered 2-4, the relationship between the ethylene / 2MP ratio in the reaction solution and the hydroformylation reaction rate is plotted in Figure 1. Figure 1 shows that the hydroformylation reaction rate can be controlled by controlling the ethylene / 2MP ratio in the hydroformylation reaction zone. Specifically, the larger the ethylene / 2MP ratio, the higher the hydroformylation reaction rate tends to be. More specifically, it can be seen that the hydroformylation reaction is highly reactive when the ethylene / 2MP ratio is 1.0 or higher, more preferably 1.5 or higher.

[0102] In Example No. 1 of Experiments, the relationship between the ethylene / 2MP ratio in the reaction solution and the hydroformylation reaction rate is plotted in Figure 2. Figure 2 shows that under conditions with a high ethylene / 2MP ratio, the reaction rate of hydroformylation is approximately 0.40-0.45 mol / L / hr, indicating excellent reactivity of the hydroformylation reaction.

[0103] Table 2 shows examples 1, 8, 13, and comparative example 9, which had similar ethylene concentrations in the reaction solution (0.316-0.321 mol / L) in experimental examples 1-4 and comparative examples.

[0104] [Table 2]

[0105] Furthermore, Figure 3 plots the relationship between the 2MP concentration in the reaction solution and the hydroformylation reaction rate. Figure 3 shows that when the 2MP concentration in the reaction solution is 0.35 mol / L or less, the reaction rate of hydroformylation is approximately 0.30 mol / L / hr or higher, indicating excellent reactivity of the hydroformylation reaction.

[0106] [Example 18] <Alcohol production> The reaction solutions obtained in Examples 1-5 were purified by distillation to obtain a mixture containing propionaldehyde and water, which was then added to a 0.2 L autoclave reactor. After adding the nickel-supported catalyst, the temperature of the reaction solution in the reactor was raised to 110°C while stirring. Next, hydrogen gas was introduced through a gas inlet valve to bring the pressure inside the reactor to 2.5 MPaG, and the reaction was carried out for 2 hours while maintaining this pressure and the temperature of the reaction solution. During the reaction, the amount of hydrogen gas consumed in the reaction was continuously introduced into the reactor while maintaining the pressure inside the reactor at 2.5 MPaG. After the reaction is complete, the reaction mixture in the reactor is cooled to room temperature, the remaining gas in the reactor is released, and the powdered nickel-supported catalyst is separated by filtration using a 40 μm filter to obtain the reaction product. The reaction product contains propanol, which is produced by the hydrogenation of propionaldehyde.

Claims

1. In a method for producing aldehydes by hydroformylating an olefin with an oxo gas containing hydrogen and carbon monoxide in the presence of a catalyst, A method for producing an aldehyde, comprising controlling the ratio of the olefin content to the unsaturated aldehyde content in the hydroformylation reaction zone so that it is equal to or greater than a predetermined value a.

2. The method for producing an aldehyde according to claim 1, wherein the predetermined value a is 0.

95.

3. The method for producing an aldehyde according to claim 1, wherein the unsaturated aldehyde comprises a compound (1) represented by the following general formula (I). 【Chemistry 1】 (In the above formula (I), R １ and R ２ Each of these independently represents an alkyl group, alkoxy group, substituted amino group, aryl group, aryloxy group, or heteroaryl group, which may have substituents.

4. A method for producing an aldehyde according to claim 1, comprising withdrawing a portion or all of the reaction solution containing an unsaturated aldehyde from the hydroformylation reaction zone, reducing the content of the unsaturated aldehyde in the withdrawn reaction solution, and then supplying the reaction solution to the hydroformylation reaction zone.

5. The method for producing an aldehyde according to claim 1, wherein the reduction of the unsaturated aldehyde content is carried out by sequentially performing the following steps (a) to (c). Step (a): Transfer part or all of the reaction solution withdrawn from the hydroformylation reaction zone to a separation container. Step (b): Remove some or all of the gas or liquid from the separation container that has a higher concentration of the unsaturated aldehyde than the reaction solution. Step (c): The liquid containing the catalyst is supplied from the separation container to the hydroformylation reaction zone.

6. The method for producing an aldehyde according to claim 1, wherein the control is performed by adjusting the gas partial pressure of the olefin in the gas phase of the hydroformylation reactor.

7. The method for producing an aldehyde according to claim 1, comprising controlling the above control based on an arbitrary analytical value of the process solution in the hydroformylation reaction zone so that the ratio is greater than or equal to a predetermined value a.

8. The method for producing an aldehyde according to claim 7, wherein the arbitrary analytical value is the hydroformylation reaction rate calculated from the hydroformylation reaction solution withdrawn from the hydroformylation reactor.

9. In a method for producing aldehydes by hydroformylating an olefin with an oxo gas containing hydrogen and carbon monoxide in the presence of a catalyst, A method for producing an aldehyde, wherein the content of unsaturated aldehyde in the hydroformylation reaction solution is 0.35 mol / L or less.

10. A method for producing an aldehyde according to claim 9, (1) A step of supplying the liquid containing the catalyst, the olefin and the oxo gas to a hydroformylation reactor, (2) After step (1) above, the hydroformylation reactor is operated so that the aldehyde and unsaturated aldehyde are produced in the hydroformylation reactor, (3) After step (2), a step of recovering the reaction solution containing the unsaturated aldehyde from the hydroformylation reactor, including, and, A method for producing an aldehyde, comprising performing at least one of the following steps (1-1) to (3-1) to maintain the content of the unsaturated aldehyde in the reaction solution recovered in step (3) at 0.35 mol / L or less. (1-1): A step of controlling the content ratio of the unsaturated aldehyde in the liquid containing the catalyst supplied in step (1), (2-1): A step of removing part or all of the unsaturated aldehyde generated in step (2) above. (3-1): A step to control the recovery rate of the reaction solution in step (3) above.

11. A method for producing an aldehyde according to claim 1 or claim 9, wherein the catalyst comprises a long-period metal-organophosphorus complex catalyst of groups 8 to 10 of the periodic table.

12. A method for producing an aldehyde according to claim 1 or claim 9, wherein the catalyst comprises a long-period metal-phosphite complex catalyst of groups 8 to 10 of the periodic table.

13. A method for producing an aldehyde according to claim 1 or claim 9, wherein the catalyst comprises a long-period metal-tris(2,4-di-tert-butylphenyl) phosphite.

14. The method for producing an aldehyde according to claim 11, wherein the long-period metals of groups 8 to 10 of the periodic table include rhodium.

15. A method for producing an aldehyde according to claim 1 or claim 9, wherein the olefin contains ethylene, the aldehyde contains propionaldehyde, and the unsaturated aldehyde contains 2-methylpentenal.

16. A method for producing alcohol, comprising producing an aldehyde by the method described in claim 1 or claim 9, and producing a corresponding alcohol from the aldehyde.

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