Process of production of phenol and acetone via acid-catalytic decomposition of cumene hydroperoxide
FIELD: industrial organic synthesis.
SUBSTANCE: invention relates to joint phenol-acetone production via selective decomposition of cumene hydroperoxide. Process is conducted in several in series connected reactors constructed in the form of shell-and-tube heat-exchangers, wherein part of decomposition product is recycled into reaction zone and mixed with feed stream to be decomposed, weight ratio of recycled stream to feed stream being less than 10. Reactors with tubular hydrodynamic characteristic have volumetric heat-exchange surface equal to or larger than 500 m2/m3. Preferably, residual concentration of cumene hydroperoxide is 0.1-0.3 wt % and its residence time in decomposition zone ranges from 0.5 to 10 min.
EFFECT: increased selectivity of decomposition at lesser recycle apparatus volume and reduced investment expenses.
11 cl, 1 dwg, 9 ex
The present invention relates to an improved method for the selective decomposition of gidroperekisi hydroperoxide (CHP) for phenol and acetone under the action of acid.
Globally, the phenol get for the most part from cumene. When the hydroperoxide is first oxidized to gidroperekisi cumene (abbreviated as GPC), and for reasons of selectivity mode are typically in the range from 20 to 30 wt.% conversion of cumene. At a later stage of the so-called concentration of the contents of the CCP, the developer usually lead 65 to 90 wt.%. So are the so-called technical CCP. At a later stage of decomposition of this technical CCP under the action of acid, in most cases, sulfuric, obtain phenol and acetone. After neutralization decomposition product from him remove these products, mainly distillative way, in the block division unit production of phenol.
Reactions as oxidation and decomposition are accompanied by undesirable by-product formation. The process of decomposition from the viewpoint of the selectivity and the yield of products in the process as a whole is of special significance. In parallel with the decomposition of the CCP for phenol and acetone dehydration takes place dimethylphenylcarbinol (abbreviated DMFC)formed before being oxidized to alpha-methylstyrene (abbreviated as AMC), which can be g derovan in the separation unit and thus returned to the stage of oxidation. But in the block decomposition of the CCP the polymerization reactions take place AMC or the reactions proceed between AMS and phenol, leading to the formation of high-boiling compounds (poly-AMS and cumylphenol), which greatly affects the selectivity and the yield of products in the process as a whole. Therefore, the decomposition process is technically should be conducted so that the maximum extent suppressed the formation of the above-mentioned high-boiling compounds.
Technical implementation of the process of decomposition has been repeatedly documented. Generally, the decomposition is carried out in the apparatus of ideal mixing. Released as a result of strong exothermic decomposition reaction of the CCP heat is removed either by evaporation of acetone (cooling the residue, see U.S. patent 5463136), or using an external refrigerators, as, for example, described in U.S. patent 4358618. In U.S. patent 4358618 describes the possibility of increasing the selectivity of such a decomposition by using in the circuit of series-connected tubular reactors. When this mode is as follows. In the main reactor, made in the form of ideal mixing reactor, carried out at temperatures in the range from 50 to 90°when applying the acid decomposition of technical CCP to a residual concentration of from 0.5 to 5 wt.%. Under these conditions the s is not less than 40 wt.% contained DMFC react with the CCP to peroxide of Dicumyl (abbreviated as MAC) and water. In the following technological scheme of the first tubular reactor, the decomposition of the CCP to a residual concentration of less than 0.4 wt.%, the temperature values at the same time similar to the temperature in the main reactor. The second tubular reactor, the decomposition of the formed before exposure AMS, phenol and acetone, the temperature set in the range from 120 to 150°C. In accordance with this main reactor and the first tubular reactor can be combined into a block decomposition of the CCP and the second tubular reactor can be designated as "block decomposition MAC". The idea of re-heat treatment of the product in a tubular reactor after decomposition of the actual code of civil procedure, as described in U.S. patent 4358618, have long been known and have been described in U.S. patent 2757209, while for the decomposition of MPC are specified temperature above 100°C, preferably from 110 to 120°C. the Purpose of this additional heat treatment was at that moment of complete dehydration DMFC to AMS. In addition to high-boiling compounds already formed by the decomposition of the CCP, the decomposition of MPC are formed and other high-boiling.
And in the patent application of the USSR 1131865 And already described two-stage method, the first stage of which the decomposition of the actual code of civil procedure, and the second stage is the decomposition of the MPC, formed in the first stage. Also, patent application USSR 1131865 And indicates for heat dissipation at each stage the product is returned with each relevant stage to receive an appropriate stage in the quantitative ratio of 20:1, and the supply is used as the catalyst of sulfuric acid only in the second stage, so to get this acid in the first stage required the subsequent return of the product of decomposition of the block decomposition MPC (second stage) in the supply flow block decomposition of the CCP (the first stage) in a volume ratio of from 1:1 to 1:10.
Our own studies have shown that the rate of decomposition of gidroperekisi cumene d CCP/dt is proportional to the concentration of CPC. Thus, for a given conversion, the yield of products taken in volume and time, will always be lower than in the ideal mixing reactor described in U.S. patent 4358618 than in a tubular reactor. Therefore, the volume of such a device the ideal mixture is always greater than the volume of the tubular reactor, if the decomposition be quantitatively respectively GIC flows respectively to the same endpoint concentrations. Accordingly, the increased is the quantity of product with a residual content of the SBC, in the apparatus of ideal mixing, compared to the amount of the decomposition product in a tubular reactor. But for reasons of safety, it is the equipment variant, when the volume of reactor decay is observed, extremely small and at the same time the surface of the heat transfer between the reacting technical CCP and the refrigerant is large. This situation is achieved if the decomposition is carried out in reactors with pipe hydrodynamic characteristic, that is, for example, shell and tube heat exchangers. This product can go on the tube and the annular space, if in this case due to the installation of a special internal device (bypass partitions) will be provided pipe hydrodynamic characteristics. The use of small reaction volumes and large surfaces of talabheim, i.e. reactors with large specific volume surfaces for heat transfer, ensures that even when the failure of, for example, pumps will not have any critical from the point of view of safety of the state despite a strong exothermic reaction of decomposition.
The use of multiple in-series shell and tube heat exchangers decomposition of technical CCP already described in the German patent 1112527. While the CCP is dispersed in an excess of sulphuric acid, and the dispersion passes through the refrigerators, in which the reaction heat is removed, followed by the separation from each other of sulfuric acid and organizations who eskay phase. Sulfuric acid is returned to the process, the decomposition product is subjected to neutralization and processing. But with the help of this so-called heterogeneous decomposition do not achieve high selectivity, because the circulation of sulfuric acid increases the occurrence of side reactions with the formation of high-boiling compounds.
Therefore, as in U.S. patent 4358618, and in U.S. patent 5254751 described homogeneous decomposition of the CCP, that is used only small amounts of sulfuric acid dissolved in the reacting mass. But unlike U.S. patent 4358618 decomposition for U.S. patent 5254751 produced in three series-connected refrigerators at temperatures in the range from 45 to 75°and it is, of course, shell and tube heat exchangers, in which the reacting mass passes through the annular space in the tube hydrodynamic conditions. When this reaction product to provide a high selectivity partially circulates in such a way that the part formed in the last fridge decomposition product is returned and mixed with the flow of the CCP, coming to the first refrigerator, and the ratio of the return stream to the feed stream of the CCP, the so-called circulation ratio λmust be in the range from 10 to 25. In addition, it is claimed that the spent solution from which istemi reactors must have a residual content of the CCP from 0.3 to 1.5 wt.%. Then the decomposition product is processed by heating in the range from 80 to 110°when pipe hydrodynamic conditions for transfer MAC, formed in the block decomposition of the CCP, phenol, acetone and AMS.
The drawing shows a schematic diagram of such a block decomposition of the FPC and the MPC described in U.S. patent 5254751. In the reactor 1 in the tube hydrodynamic conditions decompose the CCP. Part of the decomposition product is taken through line 3 and after the filing of the pipeline 6 acid used as the catalyst, are mixed in the pipe 4 in the incoming technical CCP prior to the filing of this mixture in the reactor 1. Another part of the product of decomposition is served by pipeline 5 in the tubular reactor 2 on the decomposition of EQS. The circulation ratio λ is defined as the ratio of the circulating flow in line 3 to the mixing of the CCP to the flow of the code of civil procedure, filed on line 4. The circulation of the product of decomposition is provided by the circulation pump 7. The product of decomposition, of circuit, for example, freely displayed, served by the pump 8 in the subsequent reactor 2 for the decomposition MAC.
Through the use of a reactor having a tubular hydrodynamic characteristics, principally is determined, as already described, the advantage of increased outputs adopted by volume and time, and thus the m reduced volume reactions. But required large amounts of circulating flow again increases the volume of these devices and, in addition, it becomes necessary the presence of large pipelines and pumps to allow circulation of these threads.
Thus, we have the task to create an improved method for colorectalcancer homogeneous decomposition of the CCP to phenol and acetone, notable along with a high selectivity by reducing capital expenditures.
In accordance with the invention this problem is solved on the basis of paragraph 1 of the claims due to the use of the method for production of phenol and acetone by the method of colorectalcancer homogeneous decomposition of the CCP in the block having one or more reactors with pipe hydrodynamic characteristic decomposition of the CCP, with some coming from these reactors flow decomposition product is returned to the process and mixed with the feed stream containing the CCP and sent to the block decomposition method, which differs in that the quantitative ratio of the returned partial flow decomposition product stream containing CPC and directed to decomposition, is less than 10.
Quite unexpectedly it was found that, contrary to the provisions of the U.S. patent 5254751 PR is the decomposition of the CCP does not require keeping the circulation relations from 10 to 25 to provide a high selectivity. Moreover, it was found that by reducing the circulation of the relations below 10, preferably from 2 to 9, most preferably from 5 to 7, ceteris paribus can be achieved by increasing the selectivity.
Own research, conducted in the framework of the present invention have shown that, under otherwise equal reaction conditions in the specified block decomposition of the CCP while increasing circulation should be increased supply is used as the acid catalyst in order to obtain the same decomposition of the CCP to the same set its residual concentrations at the same time the products of the reaction in the reactor system. But the presence of more acidic environment during the decomposition reaction increases, of course, the formation of by-products and thereby reduces the selectivity. Therefore, in accordance with the present invention it is necessary to constantly strive for extremely low circulating relations.
As already mentioned, for reasons of safety it is necessary to ensure that released when a strong exothermic reaction heat can reliably be discharged at any time and at any point to prevent the uncontrolled conditions of the reaction, that is, even if in an emergency situation in BC is ke decomposition will stop temporarily. In order to avoid the need for a 100%reserve technical components with the respective control devices in practice I prefer to provide a large area of heat transfer, reliably providing and emergency situations sufficiently high heat. As the reduced circulating relations concentration of the CCP at the entrance to the block decomposition increases (because at low circulating flows technical CCP is less diluted), for reasons of safety become necessary and, accordingly, increased heat exchange surface, in particular in areas of high concentrations of the CCP, i.e. primarily at the entrance to the block decomposition. Thus, the decrease in circulating relationship is usually limited to the provided block decomposition in the lower range of safety reasons. This results in the traditionally used blocks of decomposition, as, for example, preferably used shell and tube heat exchangers, to the fact that in accordance with the claimed invention particularly preferred be circulating relations from 5 to 7, as they are still simple enough to implement them from the point of view of safety. The corresponding calculation apparatus may be, for example, provide the but even in the absence of flow in the reactors of the reaction heat can be abstracted into the environment due to free convection in the reacting mass, or by other measures.
For this example, the first reactor is designed as a shell and tube apparatus can be installed vertically, with the reacting mass passes through the tubular space through the apparatus from the bottom up, and technical CCP is dosed at the bottom. In this case, when the failure of the circuit vacated the heat can still be sufficiently allocated due to free convection. Another possibility is that the pump for circulation, will be installed with provision, however, for example, two of the circulating pump must be installed in parallel and simultaneously. When the failure of one pump, the circulation is sufficiently supported by others. Further, when the malfunction of the circuit may be submitted in the form of washing a sufficient amount of cumene, and thus can be cooled and diluted reacting mass. All these are measures that can be performed on the basis of modern technology, they can, of course, to ensure the safe operation of small water relations be combined with each other.
Thus, it can be maintained even circulatio the relations less than 5 for reactors, with specific volumetric heat transfer surface (i.e. the ratio of heat transfer surface to a closed reaction volume) more than or equal to 500 m2/m3. But in these cases, the reactor preferably is selected so that in the absence of a duct provided high enough for the closed volume of the reaction heat transfer coefficient, providing a reliable heat dissipation.
But in addition to this advantage to increase the selectivity and the associated reduction in the number of the remainder are also detected and technical advantages due to the use in accordance with the invention, the mode with small circulation. For example, when the circulation ratio of 7 to install the production of phenol capacity of 200,000 tons per year required volume flow circuit 530 m3/h at the same time as when the circulation ratio of 17 required volume of the circuit is 1200 m3/H. Further, if we start from the time of the decomposition reaction of the CCP, technically usually taken as about 1 minute, when the circulation ratio 7 requires a reaction volume of approximately 9 m3and when the circulation ratio of 17 will need 20 m3. Thus, dimensions of equipment for installations with lower circulating relations and, accordingly, investments, they will replace the but below than for installations decomposition with high circulating relations.
Another advantage of the claimed method is that by reducing the circulation of relationships can be maintained and a lower residual concentration of CPC in the product decomposition without as a result of this force was reduced formation of by-products and thereby reduced selectivity. However, to reduce the residual concentration of the CCP should be increased acid consumption, which contributes to the formation of by-products; however, this effect can be at least compensated or even exceeded with increasing selectivity by reducing the circulation of the relationship, so that you can receive a lower residual concentration of the CCP at least not by reducing selectivity. When the operation mode of the residual concentration of the CCP, for example, 1% or higher risk of "leakage" of the CCP in subsequent receiving tank will be higher than under the regime of low residual concentrations. Accordingly, the costs for the implementation of safety requirements for installations with high residual concentration of CPC in the product decomposition should be higher. Therefore, we must constantly strive to have low residual concentrations.
Using the inventive method is mainly RA is the technical Annex of the CCP, containing from 65 to 90 wt.% The CCP. The remainder consists mainly of cumene and contains a small amount of by-products formed during the oxidation of cumene.
Reactor choice is made depending on the content of the SBC in a certain decomposition of technical CCP with regard to safety requirements so that could be implemented as low as possible circulation. Typically, a block decomposition of the CCP includes in accordance with the claimed invention, one or more series-connected reactors with pipe hydrodynamic characteristic, preferably a shell and tube heat exchangers, while the reacting mixture or passes through the pipe space, which is preferred, or tube. Also used in the claimed invention reactors are the plate and spiralvoice heat exchangers, which also have pipe hydrodynamic characteristics. Especially for small circulation, but not only for them, preferably using a reactor tube hydrodynamic characteristics and specific volume surface heat transfer 500 m2/m3.
Over the last reactor is selected portion of the flow decomposition product, which is returned to the process and combines the I to the first reactor or in it depending on the routing - with the feed stream of the CCP applied to the decomposition. The mixing is carried out prior to entering the first reactor. Used as the acid catalyst is introduced mainly in the reflux flow decomposition product to its Association with the supply flow of fresh technical CCP. Preferably serves and dissolved in the reaction mixture to such an amount of acid to the residual concentration of CPC in the product decomposition ranged from 0.1 to 1.5 wt.%, mainly from 0.1 to 0.3 wt.%. This usually requires filing with the reaction mixture acid of a concentration from 50 to 500 ppm weight fractions. In accordance with the claimed invention, the decomposition reaction is mostly performed in a block containing from 3 to 6 sequentially enabled cooled shell and tube heat exchangers. Diluted reflux decomposition product technical CCP passes through a tubular or annular space. When passing through the annular space by installing a bypass or longitudinal partitions can be improved variable nature of the flow. While passing through the tube space can be used and multi-units. Homogeneous decomposition is mostly performed at temperatures from 45 to 75°and an absolute pressure of from to 5 bar. Next, can have a positive influence flow in the reaction mixture in addition to acid a small amount of water, mainly from 0.3 to 1 wt.%. This water is preferably also in reflux flow decomposition product, if necessary together with the acid. The cooled shell and tube heat exchangers to remove the heat of reaction is primarily water. The residence time of the reacting mixture in the block decomposition of the CCP is, as a rule, from 0.5 to 10 minutes.
With proper calculation of the normal equipment for the claimed invention without any doubt on the safety issues can be taken predominant circulating relations reflux stream to the feed stream technical GPC in the range from 5 to 7. Along with cost savings on equipment and operation can thus be achieved by increasing yield of cumene about 0.5% or more, which, on account of the annual world production of phenol at about 7 million tons would mean a significant increase in the efficiency of production.
Not returned to the process part of the decomposition product of the CCP is displayed, as described, for example, in U.S. patent 5254751, in a special unit or at least a separate tubular reactor, which is already a known manner before further preparation is the first thread to obtain phenol and acetone are produced decomposition MAC.
The claimed method is explained in more detail below by examples, which use in no way limit.
Example 1 (comparative)
For equipment intended to perform the decomposition reaction, which has a fundamental structure in accordance with figure 1, carried out the reaction of the decomposition of technical CCP concentration of CPC 67 wt.% to its residual concentration in the product decomposition of 1.0 wt.%. Thus withstand the circulation ratio λ $ 17. Accordingly, consistent supply of sulphuric acid used as a catalyst.
As a reactor for the decomposition of the CCP use three series shell and tube heat exchanger reactor 1, figure 1), the reaction temperature is 50°C. the Absolute pressure of the reaction is 1 bar.
The resulting product decomposition of the CCP contains 0.21 wt.% high-boiling (mainly polymerized AMC and cumylphenol). After decomposition of the CCP is the decomposition MAC.
Example 2 (corresponding to the claimed invention)
The decomposition of the CCP in example 1 is produced under other equal conditions with the circulation with respect to 7, by agreeing consumption of acid set the residual concentration of CPC in the product decomposition of 0.25 wt.%. The decomposition product also contains 0.21 wt.% high-boiling.
Though the OC reduced the residual concentration of the CCP, that in example 1 can be obtained only as a result of increased consumption of acid, positively influencing the formation of by-products, in this example, reach by reducing circulating relationship with the same selectivity as in comparative example 1. The decomposition reactors and pipelines could have smaller size. Besides low residual content of the CCP provides advantages from the point of view of safety for the subsequent blocks installation.
Example 3 (corresponding to the claimed invention)
The decomposition of the CCP in example 1 to produce ceteris paribus, including the residual concentration of CPC in the product decomposition of 1 wt.%, with a circulation ratio of 7. The high-boiling fraction in the product decomposition is 0.16 wt.%. By reducing the circulation of the relationship was significantly increased compared with example 1 selectivity. Comparison with example 2 shows that by increasing the residual concentration of CPC in low circulation can be improved selectivity.
Examples 4-8 (corresponding to the claimed invention)
The decomposition of the CCP in example 1 is produced under other equal conditions at different water relations in such a way that a decomposition product with a consistent flow of acid you constantly is arrivalsa residual concentration of CPC 0.25 wt.%. Further, the content of high-boiling product of decomposition is determined, respectively, depending on the circulation of the relationship.
The results are presented in the table.
Table. The concentration of high boiling at different circuital relations with constant residual concentration of CPC
|The circulation ratio||9||8||7||6||5|
|The concentration of high-boiling (%)||0,25||0,23||0,21||0,19||0,17|
Clearly shows that at a constant residual concentration of the CCP, but with reduced circulating regarding reduced formation of high-boiling, i.e. thus increasing the selectivity.
For equipment intended to perform the decomposition reaction, which has a fundamental structure in accordance with U.S. patent 4358618, conduct the reaction of the decomposition of technical CCP concentration of CPC 67 wt.% first, in the apparatus of ideal mixing at 50°to its residual concentration of 2.75 wt.%, and then in a tubular reactor at 50°to its residual concentration of 0.2 wt.%. Product razloga the Oia contains 0.20 wt.% high-boiling.
As examples 4 through 8, when using the claimed invention achieve high selectivity.
1. Method for production of phenol and acetone by acid-catalyzed homogeneous decomposition of gidroperekisi of cumene in the block decomposition with one or more reactors having a tubular hydrodynamic characteristic, for the decomposition of the gidroperekisi cumene, wherein the portion emerging from these reactors, the product stream is returned to the process and combined with the feed stream of gidroperekisi cumene supplied to the block decomposition, characterized in that the mass ratio of return in the process of partial flow decomposition product to the supply flow gidroperekisi cumene applied to the decomposition of less than 10, and a reactor having a tubular hydrodynamic characteristics, possess a specific volume surface for heat transfer, is equal to or more than 500 m2/m3.
2. The method according to claim 1, characterized in that the block decomposition contains one or more series shell and tube heat exchangers used as a reactor for the decomposition of the gidroperekisi cumene.
3. The method according to claim 2, characterized in that the block decomposition contains from three to six shell and tube heat exchangers used as a reactor for the decomposition of headrope is ekici cumene.
4. The method according to claim 2 or 3, characterized in that the reaction mixture passes through the tube space of the shell and tube heat exchangers.
5. The method according to any one of claims 1 to 4, characterized in that the mass ratio of return in the process of partial flow decomposition product to the supply flow gidroperekisi cumene supplied to the decomposition, is in the range from 5 to 7.
6. The method according to any one of claims 1 to 5, characterized in that the residual concentration of gidroperekisi cumene in product decomposition of gidroperekisi cumene is in the range from 0.1 to 1.5 wt.%.
7. The method according to claim 6, characterized in that the residual concentration of gidroperekisi cumene in product decomposition of gidroperekisi cumene is in the range from 0.1 to 0.3 wt.%.
8. The method according to any one of claims 1 to 7, characterized in that the decomposition gidroperekisi cumene produced in the temperature range from 45 to 75°C and absolute pressure of 1 to 5 bar.
9. The method according to any one of claims 1 to 8, characterized in that the residence time of the reacting mixture in the block decomposition of gidroperekisi cumene is in the range from 0.5 to 10 minutes
10. The method according to any one of claims 1 to 9, characterized in that the content of gidroperekisi of cumene in the supply stream is in the range from 65 to 90 wt.%.
11. The method according to any one of claims 1 to 10, characterized in that the catalyst used sulphuric acid.
FIELD: industrial organic synthesis.
SUBSTANCE: invention relates to production of phenol via acid catalytic decomposition of cumene hydroperoxide followed by isolation of phenol from decomposition products and purification of phenol to remove trace impurities including acetol. Purification of phenol is accomplished through hetero-azeotropic rectification with water. Acetol is isolated as a part of liquid-phase side stream from semiblind plate located within exhausting section of hetero-azeotropic rectification column. Side stream is supplemented by cumene and used to supply stripping column, from which fraction of acetol/cumene azeotropic mixture is taken as distillate and residue is returned under semiblind plate of hetero-azeotropic rectification column to be further exhausted. From the bottom of the latter, crude phenol is withdrawn and passed to final purification from the rest of reactive trace impurities. Acetol/cumene azeotropic mixture is subjected to heat treatment at 310-350°C, which may be performed in mixtures with high-boiling production waste or in mixtures with bottom product of rectification column for thermal degradation of high-boiling synthesis by-products, which bottom product is recycled via tubular furnace. Above-mentioned semiblind plate, from which side stream is tapped, is disposed in column zone, wherein content of water is minimal and below which contact devices are positioned with efficiency at least 7.5 theoretical plates. Side stream with cumene added to it is passed to the vat of stripping column with efficiency at least 15 theoretical plates.
EFFECT: minimized content of acetol in purified phenol and reduced power consumption.
5 cl, 3 dwg, 6 tbl, 4 ex