JP3517950B2 - Method for producing aldehydes - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an improved method of hydroformylation in the hydroformylation reaction zone in which olefins are reacted with carbon monoxide and hydrogen in the presence of a rhodium catalyst having an organophosphorus compound as a ligand. It is about. More specifically, the present invention economically and efficiently recovers the unreacted olefin from the reaction solution taken out from the hydroformylation reaction zone without substantially deactivating the rhodium catalyst, and recovers the recovered unreacted olefin. The present invention relates to a method for hydroformylating an olefin, which comprises supplying the hydroformylation reaction zone.

[0002]

2. Description of the Related Art A method for carrying out a hydroformylation reaction of an olefin in the presence of a rhodium catalyst is conventionally known.
Also, some methods have been disclosed in the past for separating unreacted olefin, aldehyde product and catalyst from the hydroformylation reaction product solution.

For example, in Japanese Unexamined Patent Publication No. 52-125103, unreacted olefin, hydrogen,
After stripping the carbon monoxide and aldehyde products and cooling the vapor mixture, flash separation separates the unreacted olefins, hydrogen and carbon monoxide from the aldehyde products. It is disclosed that the gaseous stream containing the separated unreacted olefin is mostly recycled to the reaction zone.

However, in this case, it is obvious that the flash separation alone cannot completely separate the olefins due to the large latent heat of vaporization of the olefins, which leads to a substantial loss of the olefins. In order to prevent such substantial loss of olefin, JP-A-3-101633
Discloses a method for recovering olefins by using a scrubber facility.In these recovery methods, in order to absorb olefins and aldehydes in a stripped catalyst solution and recycle them to a reactor, dimerization by aldehyde self-condensation is performed. It is expected to lead to an increase in high boiling products such as bodies and trimers, or esters.

Further, JP-A-59-70634 discloses a method for producing an aldehyde by reacting an olefin with carbon monoxide and hydrogen in the presence of a water-soluble rhodium-phosphine complex compound. As a method of recovering, a stripping tower using synthesis gas is used, but in this method, the catalyst solution is separated into a water tank in the water phase / organic phase separation step before entering the stripping tower, so that the catalyst solution is substantially Not included.

Further, Japanese Patent Publication No. 3-502449 discloses a method of bringing at least a part of a hydroformylation reaction product stream into intimate contact with carbon monoxide and a hydrogen supply. In this method, the reaction product stream is disclosed. Is withdrawn as a vapor stream from above the reactor, so no catalyst is included in the reaction product stream. On the other hand, J. Ch
em. Soc. (A), 1968, pages 2660 and below, it is shown that when Rh hydride complex is brought into contact with carbon monoxide and hydrogen at room temperature and room temperature, it becomes a dimer body, and as a result, the activity of the Rh catalyst deteriorates. is expected.

That is, a method for recovering unreacted olefin from a reaction product stream containing a catalyst liquid as in the liquid-circulation process as disclosed in US Pat. No. 4,148,830 without lowering the catalytic activity has been disclosed so far. There wasn't.

[0008]

In a liquid circulation process in which the reaction liquid taken out from the reaction region contains a catalyst liquid,
When the hydroformylation reaction is carried out in the presence of the Rh catalyst, it is difficult to recover the unreacted olefin by using the countercurrent contact tower because the activity of the Rh catalyst deteriorates. The present invention provides a method for recovering unreacted olefin economically and efficiently without substantially deactivating the catalyst in the countercurrent contact tower even in the above liquid circulation process.

[0009]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that a reaction solution taken out from the hydroformylation reaction zone is introduced into the hydroformylation reaction zone and a specific operation. The inventors have found that the above problems can be solved by bringing them into close countercurrent contact under the conditions, and completed the present invention.

That is, the gist of the present invention is a hydroformylation method of reacting an olefin with carbon monoxide and hydrogen in the presence of a rhodium catalyst having an organophosphorus compound as a ligand in a hydroformylation reaction region, The reaction liquid containing the unreacted olefin, the aldehyde product and the catalyst taken out from the hydroformylation reaction region is brought into countercurrent contact with carbon monoxide and hydrogen to remove the unreacted olefin without substantially deactivating the rhodium catalyst. An olefin hydroformylation method is characterized in that it is separated and recovered from the reaction solution, and the recovered unreacted olefin is supplied to the hydroformylation reaction zone together with the carbon monoxide and hydrogen.

The present invention will be described in detail below. The olefin used in the present invention is not particularly limited, and a single product or a mixed olefin can be used, but a preferred olefin is an olefin having 2 to 5 carbon atoms or a mixture thereof, and the most preferred olefin is It is propylene. Further, a raw material having a low purity of olefin, which contains hydrocarbons other than olefins such as paraffins, can be preferably used.

The raw material olefin is usually used without any special pretreatment, but sulfur and halogen components known as catalyst poisons or dienes, trienes, peroxides and the like are conventionally adsorbed and extracted. Those removed by a method such as distillation, heat treatment, or membrane separation can also be used. A rhodium catalyst having an organophosphorus compound as a ligand is used as the catalyst, and examples of the organophosphorus compound include trialkylphosphines such as tributylphosphine and trioctylphosphine, triphenylphosphine, tritolylphosphine, and hydrogen of a phenyl group. Triarylphosphines such as triarylphosphines substituted with sulfone groups and halogens, tricycloalkylphosphines such as tricyclohexylphosphine, monobutyldiphenylphosphine,
Examples thereof include alkylarylphosphines such as dipropylphenylphosphine, cycloalkylarylphosphines, and alkylcycloalkylphosphines.

Triaryl phosphites, optionally substituted triphenyl phosphites, triaryl phosphites such as trinaphthyl phosphite, and alkylaryl phosphites may also be used. Specifically, USP3415906, USP4599206, US
P4351759, USP4748261, USP45
67306, USP5235113 and USP5227.
532 and the like, but the present invention is not limited to the type of organic phosphorus compound.

Two or more kinds of these organic phosphorus compounds can be used as a mixed ligand. Further, the above organic phosphorus compound and a pentavalent organic phosphorus compound such as triphenylphosphine oxide may be mixed and used. Rhodium sources include rhodium complexes such as hydridocarbonyltris (triphenylphosphine) rhodium and acetoxybis (triphenylphosphine) rhodium, as well as organic salts such as rhodium acetylacetonate and rhodium acetate, inorganic salts such as rhodium nitrate, and oxidation. Oxides such as rhodium are also used. Although rhodium may be directly fed to the hydroformylation reactor, it is treated with carbon monoxide and hydrogen under the elevated temperature and pressure in the solvent together with the organophosphorus compound ligand outside the reactor, and It is also possible to prepare the catalyst solution. The solvent for preparing this catalyst is usually selected from the reaction solvents described below, but it does not have to be the same as the reaction solvent. The conditions for preparing the catalyst are usually rhodium concentration of several ppm to several weight%, and the ratio of the organophosphorus compound ligand to rhodium is P / Rh = 1 to 1 in molar ratio.
0000, temperature is 60 to 200 ° C, pressure is normal pressure to 200
The processing time is in the range of several minutes to several tens of hours.

The above treatment may be a batch type or a continuous type. As the reaction solvent for the hydroformylation, the olefin itself may be used as a solvent, or the aldehyde produced or a high boiling point product produced as a by-product may be used. Other hexane, octane and other aliphatic hydrocarbons, toluene, xylene and other aromatic hydrocarbons, cyclohexane and other alicyclic hydrocarbons, butanol, octanol, polyethylene glycol, polypropylene glycol and other alcohols, triglyme, tetraglyme and other Those which dissolve ethers, esters such as dioctyl phthalate, or catalysts such as water and do not adversely affect the reaction can be used. The hydroformylation reaction conditions are usually hydrogen partial pressure of 0.1 to 200 kg / cm 2 G,
Carbon monoxide partial pressure 0.1~200kg / cm ² G, all圧数 ^{kg / cm 2 G~300kg / cm 2} G, hydrogen partial pressure / carbon monoxide partial pressure = 0.1 to 10, temperatures from 60 to 200 The temperature and the rhodium concentration are several ppm by weight to several percent by weight, P / Rh in the organophosphorus compound ligand is 1 to 10000 (molar ratio), and the reaction time is several minutes to several tens of hours.

The reaction liquid taken out as described above is
It is introduced into the upper portion of a countercurrent contact column having 4 to 100 theoretical plates without releasing the pressure, that is, at substantially the same pressure as the reaction zone. When the theoretical plate number of the countercurrent contact column is less than 4, it is not preferable because entrainment of the aldehyde product occurs. Further, if the number is more than 100 steps, it will only lead to an unnecessary increase in equipment cost.

On the other hand, carbon monoxide and hydrogen were introduced from the bottom of the column and brought into countercurrent contact with the above reaction solution taken out from the reaction zone, and the unreacted olefin obtained from the top of the column was hydroformyl together with the above carbon monoxide and hydrogen. Recycle to the chemical reaction zone. At this time, the operating conditions of the countercurrent contact tower are such that the residence time of the countercurrent contact tower is 4 hours or less, preferably 0.01 to 4 hours, and the tower bottom temperature is maintained in the range of 50 to 150 ° C. or less. Formula F = θ × exp [10000 ((1/383)-(1 /
(T + 273)))] (wherein θ represents a residence time (hr) and T represents a column bottom temperature (° C.)), and the F value is 0.35 or less, preferably from 0.01 The unreacted olefin can be separated and recovered from the reaction liquid without substantially deactivating the rhodium catalyst by adjusting the residence time and the column bottom temperature to each other so as to be 0.35. (The method according to claim 2) When the tower bottom temperature of the countercurrent contact tower is lower than 50 ° C, the recovery rate of unreacted olefin is lowered,
Excessive temperatures above 0 ° C. are not preferable because they increase by-products and decrease the activity of the rhodium catalyst. The residence time θ in the present invention refers to the bottom residence time of the liquid based on the bottom of the contact tower. Further, the F value calculated by the above equation is 0.
If a condition of more than 35 is adopted, the deactivation rate of the rhodium catalyst becomes large, which is disadvantageous in industrial practice.

Further, as another method for preventing deactivation of the rhodium catalyst, olefin is added to the bottom of the countercurrent contact column at an olefin / Rh molar ratio of 0.6 or more, preferably 1.0 to 50.
It is possible to achieve the object of the present invention by making it exist within the range. (The method according to claim 3) If the olefin / Rh molar ratio is less than 0.6, the activity of the rhodium catalyst is lowered, and the olefin is wastefully supplied even if the molar ratio is too large. Is.

As a method for allowing the olefin to exist at the bottom of the countercurrent contact tower, a method of supplying olefin or a vapor or a solution containing olefin to the bottom of the tower or a method of supplying unreacted olefin from the top of the contact tower is used. Examples include a method using a countercurrent contact column having a theoretical plate number smaller than the theoretical plate number required for complete recovery. The method of the present invention comprises claim 2.
And the method according to claim 3 can be carried out in combination, but by using any one of the methods, the unreacted olefin is recovered without substantially deactivating the rhodium catalyst. The purpose can be fully achieved.

In the present invention, the phrase "do not substantially deactivate the rhodium catalyst" means that the deactivation rate of the rhodium catalyst is 1% / day or less. Further, the catalyst liquid containing the aldehyde product flowing out from the bottom of the column may be separated into the aldehyde product by a known method such as distillation in a subsequent step, and the liquid containing the solvent and the catalyst may be recycled to the hydroformylation zone. it can.

[0021]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples without departing from the gist thereof. Examples 1 to 8 and Comparative Examples 1 to 3 A hydroformylation reaction of propylene (hereinafter referred to as PPY) was performed using the apparatus shown in FIG. The catalyst liquid conditions in the pipe (12) were Rh 330 mg / l and triphenylphosphine (hereinafter referred to as TPP) 21.1 wt%. The reactor (4) was maintained at 100 ° C. and a total pressure of 17 kg / cm ² G, and when propylene (line 1) was charged at 7.5 kg / H, butyraldehyde (line 11) was 11.8 kg.
/ H produced. Propylene (pipe line 1) has a purity of 99 mol
% Gas, water gas (pipe 2) is H ₂ + CO 9
8.8%, using a gas H ₂ / CO ratio 1.015, a pressure of the reactor (4) was supplemented to maintain the 17kg / cm ² G. The inert and some unreacted materials were released to vent (3). The heat exchanger (18) was heated and cooled in order to adjust the charging temperature to the countercurrent contact tower. Countercurrent contact tower (1
A pipe (2) is provided in 5) so that propylene can be supplied to the bottom of the tower.
0) and a part of the recycled gas containing propylene (19). The deactivation rate of the catalyst rhodium when operating under the operating conditions of the countercurrent contact tower as shown in Table 1 is as shown in Table 1.

[0022]

[Table 1]

[0023]

Industrial Applicability By using the method of the present invention, unreacted olefins can be separated and recovered from a reaction solution containing a rhodium catalyst without substantially deactivating the catalyst, and can be economically and efficiently recycled into the reaction region. Because it can be used, it has high industrial utility value.

[Brief description of drawings]

FIG. 1 shows a flow diagram of an example of the present invention and a comparative example.

[Explanation of symbols]

4: Stirred tank reactor 6: Gas-liquid separator 9: Aldehyde separation tower 15: Countercurrent contact tower 18: Heat exchanger C: Compressor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-273840 (JP, A) JP-B-51-6124 (JP, B1) JP-A-3-502449 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C07C 47/02-47/198 C07C 45/50

Claims (7)

(57) [Claims] 1. In the hydroformylation reaction region, in the presence of a rhodium catalyst having an organophosphorus compound as a ligand,
A method for producing an aldehyde, which comprises reacting an olefin with carbon monoxide and hydrogen, wherein a reaction liquid containing an unreacted olefin, an aldehyde product, and a catalyst taken out from the hydroformylation reaction region is treated with carbon monoxide and hydrogen .
Flow contact tower residence time less than 4 hours and tower bottom temperature 50
The expression F = θ × exp [10000 ((1/383) − (1 /
(T + 273)))] (wherein θ represents a residence time (hr), and T represents a bottom temperature.
(Representing (° C.)) has an F value of 0.35 or more
Adjust the residence time and the bottom temperature to each other so that
The unreacted olefin is separated and recovered from the reaction liquid without contact with the countercurrent by substantially deactivating the rhodium catalyst, and the recovered unreacted olefin is supplied to the hydroformylation reaction region together with the carbon monoxide and hydrogen. A method for producing an aldehyde, comprising: 2. The method for producing aldehydes according to claim 1, wherein the countercurrent contact is carried out while olefin is present at the bottom of the countercurrent contact tower in an olefin / Rh molar ratio of 0.6 or more. 3. The aldehydes according to claim 2 , wherein the countercurrent contact is carried out while the olefin is present at the bottom of the countercurrent contact tower so that the olefin / Rh molar ratio is within the range of 1.0 to 50. Production method. 4. The method for producing an aldehyde according to claim 2 or 3 , wherein the method of causing the olefin to exist at the bottom of the countercurrent contact tower is to partially feed the olefin or a gas containing the olefin to the bottom of the tower. Wherein the olefin is ethylene, and method for producing aldehydes according to claims 1 to 4 aldehyde product is propanal. Wherein the olefin is propylene, and method for producing aldehydes according to claims 1 to 4 aldehyde product is n- butanal and isobutanal. 7. olefin is butene and the aldehyde product manufacturing method of the aldehyde according to claims 1 to 4 which is a mixture of branched pentanal and linear pentanal.