JPH0342250B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for industrially producing tertiary butyl alcohol (hereinafter abbreviated as TBA) with high selectivity by reacting isobutylene and water. From the _C4 mixture, isobutylene is hydrated and
Many methods of producing TBA are known. These methods are classified into 1. Methods using different catalysts, 2. Methods using different reaction systems (heterogeneous system, homogeneous system), and 3. Methods characterized by the solvent added to make the system homogeneous. For example, a method using sulfuric acid as a catalyst has been known for a long time, but by-products (dimers, trimers)
There are problems such as large quantities and high quality equipment materials.
Furthermore, in the method using a solid acid or the like, it is necessary to carry out the reaction at high temperature and high pressure. On the other hand, with strong acid type ion exchange resins, it is possible to carry out the reaction quickly at relatively low temperatures, and many methods have been proposed to increase the yield under this catalyst. For example, as a method for reacting in a heterogeneous system without using a solvent, etc., there are
30104, JP-A-54-30105, JP-A-55-85529, JP-A-108825, JP-A-52-151106, etc. are known, but due to the problem of reaction speed, it is necessary to There is an industrial disadvantage in that the container becomes larger. On the other hand, when the reaction is carried out in a homogeneous system, a method using an organic acid as the type of solvent (Japanese Patent Publication No. 53-20482,
(Japanese Patent Publication No. 53-14044, Special Publication No. 56-22855, etc.) is known, but in order to increase the isobutylene unit consumption, the generated TBA and organic acid further react, and a large amount of organic acid ester is produced as a by-product. It is necessary to perform operations such as hydrolyzing the resulting ester, and the material of the equipment also needs to be of a higher quality. Furthermore, a method using a polar solvent (Japanese Unexamined Patent Publication No. 1983-
34643, JP-A-57-108028, JP-A-56-87526, JP-A-57-10853, JP-A-56-10124, etc.), but these depend on the combination of the solvent used and the reaction process. Efforts are being made to increase yield.
Especially when using TBA as a solvent (Tokuko Sho 57
-10853, JP-A-57-108028), there are problems such as the reaction is an equilibrium reaction, and the raw material C ₄ , water, and TBA do not mix in a desired ratio, so a homogeneous phase may not be formed. In order to increase the yield to an industrial level, considerable innovation is required in the reaction process. Therefore, according to the method of Special Publication No. 57-10853, water
It is stated that 10 to 500 moles of alcohol (including TBA) are added per 100 moles, but this also includes conditions that result in a heterogeneous phase, and if the reaction is carried out under such conditions, It can be inferred that a large amount of catalyst is required at the inlet of the reactor until the reaction does not proceed and a homogeneous phase is formed, and it is not easy to commercialize the process under these conditions. On the other hand, JP-A-56-
According to the method of No. 10124, it is described that the above conditions are limited to a certain part of the composition region where the composition of the reaction zone is homogeneous. Furthermore, the description therein states that the isobutylene conversion rate is excellent for raw material compositions near the boundary between uniform and non-uniform. However, even within this range, if the reaction is carried out in a region with low water and TBA contents, the raw material isobutylene will dimerize, resulting in poor selectivity. ,
When carrying out this reaction in a conventional multistage reactor, it is necessary to start from the above range in order to minimize the amount of catalyst, and a decrease in selectivity is unavoidable. Conversely, when trying to convert isobutylene to TBA with high selectivity, the reaction starts from a solution with a low concentration of isobutylene-containing hydrocarbon in a mixed solution of isobutylene-containing hydrocarbon, water, and TBA, and water is successively supplied. However, if this method is used alone, the conversion rate of isobutylene to TBA will decrease rapidly once the isobutylene has reacted to a certain extent, and a huge amount of catalyst will be required to obtain a high conversion rate. . Also, a method is described in which water is added to the reaction liquid exiting the reactor to separate the _two phases, and the oil phase is sent to the next reactor. Since the composition of the oil phase is determined by phase equilibrium, it is necessary to extract with a large amount of water in order to increase the concentration of C ₄ fraction, and the aqueous solution from which TBA is extracted is dilute. Recovering TBA from raw materials requires a lot of energy and operations, and is not a desirable method for industrial use. The present invention has been made in view of the above, and is capable of facilitating the reaction and obtaining TBA with high selectivity and high yield when synthesizing TBA from isobutylene or an isobutylene-containing hydrocarbon and water. The purpose is to provide a manufacturing method. As a result of intensive research, the present inventors have found that in a multistage reaction between isobutylene and water, the first reaction zone and the second reaction zone are physically separated by distillation, and TBA is supplied to the first reaction zone and the second reaction zone. Concerning the concentration of the C4 fraction in the water, _C4 mixed solution, the concentration of the _C4 fraction in the TBA _- water- _C4 fraction mixed solution supplied to the second reaction zone is supplied to the first reaction zone. TBA-Water-
We discovered that increasing the concentration of the C ₄ fraction higher than the concentration of the C ₄ fraction in the C 4 fraction mixed solution allows the reaction to proceed smoothly and further allows the reaction to be carried out with high selectivity and high yield.
The present invention has now been completed. That is, the present invention provides a method for producing tertiary butyl alcohol by reacting isobutylene or an isobutylene-containing hydrocarbon with water in the presence of a cation exchange resin. and water in the presence of a cation exchange resin to obtain a reaction mixture consisting of tertiary butyl alcohol, unreacted isobutylene or unreacted isobutylene-containing hydrocarbon, and water; or a step of separating unreacted isobutylene-containing hydrocarbon and tertiary butyl alcohol aqueous solution, the separated unreacted isobutylene or unreacted isobutylene-containing hydrocarbon and water in the presence of a cation exchange resin in a second reaction zone. to obtain a reaction mixture consisting of tertiary butyl alcohol, unreacted isobutylene or unreacted isobutylene-containing hydrocarbon, and water, and a part of the separated tertiary butyl alcohol aqueous solution is transferred to a first reaction zone and /or a step of supplying to the second reaction zone, at this time, the tertiary butyl alcohol-water-isobutylene or isobutylene-containing hydrocarbon mixture near the raw material supply ports of each of the first reaction zone and the second reaction zone is uniform. The composition is such that it becomes a phase, and
The concentration of isobutylene or isobutylene-containing hydrocarbon in the tertiary butyl alcohol-water-isobutylene or isobutylene-containing hydrocarbon mixture solution supplied to the second reaction zone is adjusted to the tertiary-butyl alcohol-water-supplied to the first reaction zone. The gist of the present invention is a method for producing tertiary butyl alcohol, characterized in that the concentration of isobutylene or an isobutylene-containing hydrocarbon is maintained higher than the concentration of isobutylene or an isobutylene-containing hydrocarbon in a mixed solution of isobutylene or an isobutylene-containing hydrocarbon. Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows an example of the present invention. However, the present invention is not limited to this. The process shown in Figure 1 basically consists of a first step in which _C4 hydrocarbons and water are reacted in the presence of a cation exchange resin to obtain a reaction mixture consisting of TBA, unreacted _C4 hydrocarbons, and water. It consists of a reaction zone A, a second reaction zone C, and a first distillation zone B and a second distillation zone D that distill and separate unreacted C ₄ hydrocarbons and a TBA aqueous solution. A mixture of C ₄ hydrocarbon, water and TBA adjusted to a predetermined composition is supplied from line 2 to the first reaction zone A. In this case, the _C4 hydrocarbons are in line 1
Water and TBA are supplied through line 4, where a part of the TBA aqueous solution distilled and separated from the first distillation zone is
6, the solution is led to a TBA aqueous solution storage tank E, where water is supplied from line 7 to form a TBA aqueous solution with a predetermined composition, and the solution is made to join line 2 via line 8.
In the present invention, it is important to determine the composition so that the TBA-water-C ₄ hydrocarbon mixture near the raw material supply port of the first reaction zone A becomes a homogeneous phase. The reaction mixture consisting of TBA, unreacted C ₄ hydrocarbon and water obtained by the reaction in the first reaction zone is fed to the first distillation zone B through line 3. In the first distillation zone B, unreacted C ₄ hydrocarbons and TBA aqueous solution are separated. A portion of the separated TBA aqueous solution is sent to a purification process (not shown) through lines 4 and 5. The other part is supplied to the first reaction zone A through lines 4, 6, 8, and 2 with the water content adjusted as described above. On the other hand, a part of the unreacted C ₄ hydrocarbons is circulated through lines 9 and 10, and the other part is supplied to the second reaction zone C through lines 9, 11, and 12. It should be noted that unreacted isobutylene or isobutylene-containing hydrocarbons separated by the distillation zone from the reaction mixture obtained from the first reaction zone of the present invention may contain some TBA and water; There is no need to separate them by distillation. The water and TBA supplied to the second reaction zone C are
A part of the TBA aqueous solution distilled and separated from the second distillation zone is led to the TBA aqueous solution storage tank F via lines 14 and 16, where water is supplied from line 17 to form a TBA aqueous solution with a predetermined composition, and then via line 18 to the TBA aqueous solution storage tank F. Join 12. The water and TBA supplied to the second reaction zone C are partially or completely fed to the first reaction zone C.
Of course, it is also possible to use what is obtained from the distillation zone. In the present invention, as in the case of the first reaction zone, TBA-
It is important to determine the composition so that the water- _C4 hydrocarbon mixture forms a homogeneous phase. In the present invention, the TBA-water-
It is important to maintain the C ₄ hydrocarbon concentration in the C ₄ hydrocarbon mixture solution higher than the C ₄ hydrocarbon concentration in the TBA-water-C ₄ hydrocarbon mixture solution supplied to the first reaction zone A. . On the other hand, JP-A-56-
No. 10124 merely discloses that the composition of the raw materials supplied to each reaction zone may be within a certain range. The reaction mixture consisting of TBA, unreacted C ₄ hydrocarbon and water obtained by the reaction in the second reaction zone is fed to the second distillation zone D through line 13. Second
In distillation zone D, unreacted C ₄ hydrocarbons and TBA aqueous solution are separated. A part of the separated TBA aqueous solution passes through lines 14 and 15 to a purification process (not shown)
etc. will be sent to. As mentioned above, some of the other parts adjust the water content to line 14, 16, 18, 12.
It is supplied to the second reaction zone C through. Although not shown, a part of the TBA aqueous solution can be combined with the TBA aqueous solution from the first distillation zone and supplied to the first reaction zone A. Unreacted C ₄ separated by distillation from the second distillation zone D
A part of the hydrocarbon is circulated through lines 19 and 20, and the other part is discharged to the outside of the system through lines 19 and 21. In addition, if you want to finely adjust the composition of the reaction mixture at the inlet of the reaction zone, use line 2 shown as a broken line in the figure.
The reaction mixture at the outlet of each of the first reaction zone A and the second reaction zone C may be circulated to the inlet as shown in 2 and 23. Incidentally, since the reaction according to the present invention is an exothermic reaction, if the temperature of the reaction zone rises due to the reaction heat, the reaction can be circulated after cooling. In Figure 1, there are two reaction zones, including unreacted isobutylene in line 21.
When further synthesizing TBA from C ₄ hydrocarbons,
In line 12 feeding the second reaction zone C
The TBA aqueous solution is mixed with the C ₄ hydrocarbon in line 21 so that the concentration of C ₄ hydrocarbon in the TBA-water-hydrocarbon mixture is higher than that of the C 4 hydrocarbon in the TBA-water-hydrocarbon mixture. You can also add . In addition, in the present invention, the first reaction zone, the second
In each reaction zone, the catalyst layer may be divided into multiple stages and water may be added in between. The isobutylene-containing hydrocarbon used in the present invention is not particularly limited, but industrially it is a C ₄ fraction obtained from steam cracking of naphtha or catalytic cracking of heavy oil. In this _C4 fraction,
In addition to isobutylene, it contains 1-butene, trans-2-butene, cis-2-butene, n-butane, isobutane, and some amounts of C ₃ and C ₅ fractions and butadiene. The cation exchange resin used in the present invention is a strongly acidic cation exchange resin, preferably a porous one. Specifically, they are commercially available under trade names such as Revachit and Amberlight. In order to make the present invention more understandable, the present invention will be explained with reference to FIG. FIG. 3 is a triangular diagram showing the composition of a ternary system of TBA-water- _C4 hydrocarbon, with bending line X-b
-γ-Y is the boundary line between the uniform liquid phase region and the non-uniform liquid phase region, and the point Z side of this boundary line is the uniform liquid phase region. The same applies to the one shown in FIG. 2 of Japanese Patent Application Laid-Open No. 56-10124. It is advantageous for the reaction to keep the composition of the liquid supplied to each reactor on this boundary line, but when carrying out this reaction in a multi-stage reaction, it is necessary to supply water sequentially or the reaction liquid after leaving the reactor. A method of adding water to separate the two phases and sending the oil layer to the next reactor (Example 5 of JP-A-56-10124)
In such a method, as the first stage reactor changes to the subsequent reactor, the raw material composition near the inlet of each reactor will move from X to Y direction along this boundary line. . However, in the method of the present invention, on the contrary, the inlet composition of each reactor moves along the Y to X direction. Here, an example will be explained in which a C ₄ hydrocarbon containing 45% by weight of isobutylene is used as a raw material and reacted. Assuming that the inlet composition of the reaction mixture supplied to the first reaction zone is selected as b in Table 4 described below, the composition of the reaction mixture in the first reaction zone will connect point b and point α in Fig. 3 as the reaction progresses. Changes on the line from point b to point α (however, point α is 45
This is the target point where the composition changes as the reaction progresses when C ₄ containing % isobutylene is reacted from point b. In this case, the selectivity of isobutylene to TBA is approximately 100%, and other C ₄ carbonization The amount of hydrogen is such that it hardly reacts or even if it reacts, it is so small that it can be ignored. ). Now, suppose that the reaction mixture obtained from the first reaction zone is a mixture with the composition represented by point β, and the composition of the raw material supplied to the second reaction zone is adjusted by adding water to the mixture. In this case, as the amount of water added to this mixture increases, the composition of the raw material changes on the line connecting point β to point Y, and the composition approaches point Y as the amount of water added increases. When water is added, the concentration of C ₄ hydrocarbons at point γ is smaller than the concentration of C ₄ hydrocarbons at point b, so that the composition at point γ on the boundary line at the entrance of the two reaction zones is obtained. Furthermore, as is clear from this figure, in the composition between point β and point γ, the concentration of C ₄ hydrocarbons is always lower than the concentration of C ₄ hydrocarbons at point b. In contrast, in the case of the present invention, if the reaction mixture at point β is completely separated into C ₄ hydrocarbons and TBA aqueous solution by distillation, a 100% by weight distillate of C ₄ hydrocarbons represented by point minute is obtained, and from the bottom of the tower is the point
Point δ, which is the intersection of the extension of the straight line connecting point β and line YZ
A TBA aqueous solution represented by is obtained. This C ₄ hydrocarbon fraction is mixed with a TBA aqueous solution, and the C ₄ hydrocarbon concentration is higher than point b, and the boundary line X-b-γ-Y
When trying to prepare a TBA-water- _C4 hydrocarbon mixture with the composition shown above, the composition of the TBA aqueous solution to be mixed is determined by the intersection of point ε and point δ between the extension of the straight line connecting point X and point b and the line YZ. It can be seen that it lies on the ε-δ line between . In this way, the composition expressed by ε to δ is
By mixing the TBA aqueous solution, a mixed solution of C ₄ hydrocarbon, water and TBA to be fed to the second reaction zone described in the present invention can be prepared. Next, the present invention will be explained with specific examples. still,
The composition of each of the Examples and Comparative Examples was analyzed by the Karl Fischer method for water, and by gas chromatography for other components. Example 1 and Comparative Examples 1 to 3 The isobutylene-containing hydrocarbons shown in Table 1 were supplied from line 1 according to the flow shown in FIG.
We synthesized TBA. Reactors A and C and distillation column B with the structures and operating conditions shown in Table 2 correspond to the first and second reaction zones A and C, and the first and second distillation zones B and D, respectively. ,D were used. The inlet composition of each reactor (lines 2 and 12) was operated under the conditions shown in Table 3. The specific compositions of symbols a to d in Table 3 are as shown in Table 4. The reaction results were as shown in Table 5.

【table】

【table】

【table】

【table】

【table】

[Table] Comparative Examples 4 to 7 According to the flow shown in FIG. 2, TBA synthesis was performed using the isobutylene-containing hydrocarbons shown in Table 1 as raw materials. First reaction zone A, second reaction zone C, distillation zone D
The reactors A and C and distillation zone column D shown in Table 2 were used and operated under the operating conditions shown in Table 2. The composition of TBA-water- _C4 hydrocarbon supplied to the first reactor A is shown in Table 6, and the specific compositions of symbols a to d in the table are shown in Table 4. . Table 7 shows the results.

【table】

[Table] The flow shown in Figure 2 will be explained. The process shown in Figure 2 basically involves reacting a _C4 hydrocarbon with water in the presence of a cation exchange resin.
a first reaction zone A and a second reaction zone C obtaining a reaction mixture consisting of TBA, unreacted _C4 hydrocarbons and water;
and a distillation zone D that separates unreacted C ₄ hydrocarbons and TBA aqueous solution by distillation. A mixture of C ₄ hydrocarbon, water and TBA adjusted to a predetermined composition is supplied from line 2 to the first reaction zone A. In this case, the _C4 hydrocarbons are in line 1
Water and TBA are supplied through lines 7 and 9, and a part of the TBA aqueous solution distilled and separated from distillation zone D is supplied through lines 7 and 9.
The solution is then led to a TBA aqueous solution storage tank F, where water is supplied from line 10 to form a TBA aqueous solution with a predetermined composition, and the solution is made to join line 2 via line 11. The reaction mixture consisting of TBA, unreacted _C4 hydrocarbon and water obtained by reaction in the first reaction zone A is
Water is extracted from line 3, and water is supplied from line 4.
After mixing, it is fed to the second reaction zone C via line 5. The mixed mixture consisting of TBA, unreacted _C4 hydrocarbon and water obtained by the reaction in the second reaction zone C is
It is fed via line 6 to distillation zone D. In distillation zone D, unreacted C ₄ hydrocarbons and TBA aqueous solution are separated. A portion of the separated TBA aqueous solution is discharged to the outside of the system via lines 7 and 8. The other part is supplied to the first reaction zone A through lines 7, 9, 11, and 2 with the water content adjusted as described above. A part of the unreacted C ₄ hydrocarbons distilled and separated from distillation zone D is circulated through lines 12 and 13, and the other part is discharged to the outside of the system through lines 12 and 14.

[Brief explanation of drawings]

FIG. 1 is a process flow diagram showing one example of the present invention. FIG. 2 is a process flow diagram of a comparative example. FIG. 3 is a triangular diagram showing the composition of a ternary system of TBA-water- _C4 hydrocarbon. A...First reaction zone, B...Distillation zone, C...
Second reaction zone.

Claims (1)

[Claims] 1. In a method for producing tertiary butyl alcohol by reacting isobutylene or an isobutylene-containing hydrocarbon and water in the presence of a cation exchange resin, in the first reaction zone, isobutylene or an isobutylene-containing hydrocarbon and water are reacted with cations. tertiary butyl alcohol by reaction in the presence of an exchange resin;
obtaining a reaction mixture consisting of unreacted isobutylene or an unreacted isobutylene-containing hydrocarbon and water;
The reaction mixture is combined with unreacted isobutylene or unreacted isobutylene-containing hydrocarbon in a distillation zone.
a step of separating the separated unreacted isobutylene or unreacted isobutylene-containing hydrocarbon and water in the presence of a cation exchange resin in a second reaction zone to produce tertiary butyl alcohol, A step of obtaining a reaction mixture consisting of unreacted isobutylene or a hydrocarbon containing unreacted isobutylene and water, and transferring a portion of the separated aqueous tertiary butyl alcohol solution to a first reaction zone and/or
or a step of supplying the mixture to the second reaction zone, in which the tertiary butyl alcohol-water-isobutylene or isobutylene-containing hydrocarbon mixture near the raw material supply ports of each of the first reaction zone and the second reaction zone is in a homogeneous phase. The composition is such that the concentration of isobutylene or isobutylene-containing hydrocarbon in the tertiary butyl alcohol-water-isobutylene or isobutylene-containing hydrocarbon mixed solution supplied to the second reaction zone is supplied to the first reaction zone. A method for producing tertiary butyl alcohol, which comprises maintaining the concentration of isobutylene or isobutylene-containing hydrocarbon higher than the concentration of isobutylene or isobutylene-containing hydrocarbon in the tertiary butyl alcohol-water-isobutylene or isobutylene-containing hydrocarbon mixed solution.