JP2013535484A - Method for producing α-methylstyrene - Google Patents

Abstract

  The present invention relates to the hydrogenation of cumene hydroperoxide by increasing the concentration through the selective hydrogenation process of cumene hydroperoxide obtained from the oxidation of cumene in the phenol production process at the maximum stabilized conditions at low concentration and low temperature. By reducing the risk of explosion during the reaction, increasing the selectivity to 90% or more and increasing the amount to cumyl alcohol, the amount of α-methylstyrene is selectively increased and the amount of cumene hydroperoxide is reduced. The present invention relates to a method for producing α-methylstyrene which can be controlled to control the production amount of α-methylstyrene to meet market demand.

Description

  The present invention relates to a method for producing α-methylstyrene for selective production of α-methylstyrene.

  Alpha-methylstyrene (hereinafter referred to as “AMS”) is variously used as an additive in the production of a specific copolymer such as ABS and a novel polymer. AMS also has application as an intermediate in the production of fine compounds such as unsaturated AMS isomers. These heteromers are used as molecular weight control agents in the production of copolymers such as acrylonitrile-butadiene-styrene resin and styrene-butadiene rubber. The hydrogenated form of AMS heteromer has industrial value as a component in the lubricating composition.

  Such AMS is produced as a by-product of the phenol production process, but generally, phenol and AMS are produced through the oxidation and dehydration processes using cumene as a raw material. FIG. 1 is a process diagram schematically showing a conventional phenol production process.

  Referring to FIG. 1, the existing method is to oxidize cumene in the presence of oxygen in an oxygen reactor 1 fed with cumene, to obtain about 24% by weight cumene hydroperoxide (CHP) and a small amount of cumyl alcohol ( A stream converted into CA) is produced and transferred to the reservoir 2, and then the CHP containing stream of about 24 wt% is concentrated to about 82 wt% by the stripper 3. Thereafter, the concentrated CHP and CA-containing stream is supplied to the cracking reactor 5 via the reservoir 4 and dehydrated under an acid catalyst to produce phenol and acetone from the CHP, and from the CA. It produces α-methylstyrene (AMS). However, in the case of the above-mentioned method, in the cumene oxidation step, CA is produced in an amount of only 0.035 mol% with respect to 1 mol of CHP. Therefore, the amount of AMS produced in the phenol production step is the extreme produced in the cumene oxidation step. Limited by a small amount of cumyl alcohol.

  Therefore, research to selectively increase the production of AMS has been carried out, and a part of CHP emitted from the stripper before the decomposition reactor is selectively selected for CA. There is a method to increase production of α-methylstyrene. However, this method has a problem in stability because the conversion rate and selectivity are low, the process efficiency is low, and highly concentrated CHP is used.

  Moreover, the existing method discloses a method of converting the hydrogenation process of AMS produced for recycling to the oxidation reactor into cumene again, not mainly for the purpose of increasing the production of AMS (US Pat. 5,905,178). In addition, the conventional method is only an attempt to minimize the generation of AMS (US Pat. No. 5,530,166), and the research for increasing the production of AMS is insufficient. It is a fact.

  Therefore, the present invention is used as an additive such as ABS for the purpose of selectively increasing AMS, which has been regarded as a by-product in the phenol production process, through a selective hydrogenation process from cumene hydroperoxide to cumyl alcohol. An object is to provide a method for producing α-methylstyrene.

  The present invention also provides a method for producing α-methylstyrene, which can control the amount of cumene hydroperoxide stream injected in the hydrogenation step and can control the production amount of AMS according to the market demand.

  The present invention also significantly reduces the production of AMS by proceeding with low concentration hydrogenation of cumene hydroperoxide stream to eliminate the possibility of cumene hydroperoxide ignition and stably produce cumyl alcohol. An object of the present invention is to provide a method for producing α-methylstyrene capable of increasing the amount.

The present invention comprises (a) oxidizing cumene to produce a cumene hydroperoxide stream;
(B) separating at least a portion of the cumene hydroperoxide stream without concentrating it and selectively subjecting it to a hydrogenation reaction under a noble metal catalyst to produce cumyl alcohol; and (c) the cumyl A method for producing α-methylstyrene is provided, which comprises a step of concentrating a reaction product containing alcohol and subjecting it to a dehydration reaction under an acid catalyst to produce a product containing α-methylstyrene.

  In step (b), the cumene hydroperoxide stream can be used in the hydrogenation reaction at a concentration of about 5 to 25% by weight. In the step (b), about 5 to 50% by weight of the cumene hydroperoxide stream can be separated and used for the hydrogenation reaction. The cumene hydroperoxide stream further comprises cumyl alcohol.

  According to the method of the present invention, the selectivity of the hydrogenation reaction is 95% or more, and the conversion rate of cumene hydroperoxide is about 95% or more.

  In the step (b), a hydrogenation reaction is performed on a part of the cumene hydroperoxide stream. In the step (c), the reactant containing the cumyl alcohol does not undergo the hydrogenation reaction. Further comprising a cumene hydroperoxide stream. In the step (c), the product containing α-methylstyrene further contains phenol and acetone. The reactant containing cumyl alcohol can be concentrated to a concentration of 80 to 82% by weight and used for dehydration reaction. The method further includes neutralizing and distilling the product containing α-methylstyrene after step (c) to obtain α-methylstyrene, phenol and acetone.

  Hereinafter, a method for producing α-styrene according to a specific embodiment of the present invention will be described.

  A typical phenol process concentrates about 24-25% by weight cumene hydroperoxide (CHP) solution produced by three oxidation reactors through a stripper to about 80-82% by weight CHP solution, It is a process that is produced into phenol, acetone and AMS via a cracking reactor.

  By the way, cumene hydroperoxide is an explosive substance when mixed with air and has an ignition point between about 57-79 ° C. In addition, there is a risk of explosion and fire when in contact with organic substances, acids, bases and metallic components. In addition, it has been reported that increasing the concentration of cumene hydroperoxide lowers the runway reaction temperature and increases the risk of explosion (Thermochimica acta, 501, 2010, 65-71). Therefore, there is a need for a method of performing the phenol process in a stable manner without using a high concentration of cumene hydroperoxide as described above.

  Thus, it is very important that the cumene hydroperoxide conversion process be carried out at the most stable conditions, i.e. low cumene hydroperoxide concentration and low temperature.

  In addition, in the existing cumene oxidation process, cumyl alcohol is produced in an amount of only about 0.035 mol% with respect to 1 mol of cumene hydroperoxide, and there is a limit in increasing the production amount of α-methylstyrene.

  Thus, the present invention provides a process that can produce cumyl alcohol in a stable state using low concentrations of cumene hydroperoxide. In addition, the present invention increases the production amount of cumyl alcohol through the hydrogenation process of cumene hydroperoxide to cumyl alcohol, and then dehydrates the cumyl alcohol to significantly increase the production amount of α-methylstyrene. Try to provide a way that can be.

  According to such a preferred embodiment of the present invention, (a) a step of oxidizing cumene to produce a cumene hydroperoxide stream, (b) separating at least a part without concentrating the cumene hydroperoxide stream. A hydrogenation reaction selectively under a noble metal catalyst to produce cumyl alcohol; and (c) a reaction product containing the cumyl alcohol is concentrated and subjected to a dehydration reaction under an acid catalyst, α There is provided a process for producing alpha methyl styrene comprising the step of producing a product comprising methyl styrene.

  In the method of the present invention, the cumene hydroperoxide stream obtained by the cumene oxidation as described above is concentrated by a stripper, and then the dehydration reaction is not proceeded as it is in the decomposition reactor, but the concentration before the concentration by the stripper is reduced. In this state, by separating a part of cumene hydroperoxide obtained after the oxidation reaction and using it in the catalytic hydrogenation step, the selectivity and the conversion rate to cumyl alcohol can be improved.

  Therefore, the present invention converts cumene hydroperoxide to cumyl alcohol in the region where low concentration stability is ensured in the production process, and shows much better results than existing. That is, the present invention uses cumene hydroperoxide after oxidation of cumene without using the stream of cumene hydroperoxide before entering the cleavage reactor via a stripper as a reactant in the hydrogenation reaction. To ensure process stability.

  According to the present invention, a cumene hydroperoxide stream having a concentration of 5 to 25% by weight is produced through the step (a). The stream may contain a small amount of cumyl alcohol due to oxidation of the cumene.

At this time, the oxidation conditions are not particularly limited in the step (a), and the process proceeds under general conditions. For example, cumene is usually oxidized by auto-oxidation with an oxygen-containing gas such as air or oxygen-enriched air. This oxidation reaction is performed with or without an additive such as an alkali. The normal oxidation reaction temperature is about 50 to 200 ° C., and the reaction pressure is atmospheric pressure to about 5 MPa. When the additive is used, alkali metal compounds such as NaOH and KOH; alkaline earth metal compounds; alkali metal carbonates such as Na ₂ CO ₃ and NaHCO ₃ ; ammonia; alkali metal ammonium carbonates and the like can be used. is there.

  In step (a), the oxidation of cumene is carried out by a number of oxidation reactors, preferably three oxidation reactors, used in a normal phenol process. In the step (a), a cumene-containing stream having a cumene concentration of about 80% or more, more preferably about 98% or more is oxidized in the presence of an oxygen-containing stream to form a cumene hydroperoxide-containing stream. including.

  In addition, usual initiators may be used to promote the oxidation of cumene, such as organic hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, peroxy-based free radical initiators, or azo-based free initiators. A radical initiator or the like may be used.

  Step (b) is a step of increasing the content of cumyl alcohol by performing a hydrogenation reaction using the cumene hydroperoxide stream obtained in step (a).

  For this reason, in the step (b), a hydrogenation reaction proceeds on a part of the cumene hydroperoxide stream. In the step (b) of producing cumyl alcohol, it is preferable that about 5 to 50% by weight of the cumene hydroperoxide stream is separated and used in the hydrogenation reaction.

  The noble metal catalyst used in the hydrogenation reaction may include one or more selected from the group consisting of gold, silver, platinum, palladium, iridium, ruthenium, rhenium, rhodium and osmium. The noble metal catalyst may additionally include a support selected from the group consisting of alumina, silica, clay, carbon, zirconia, titania, mesoporous molecular sieves, and mixtures thereof.

  The noble metal catalyst is used in an amount of about 1 to 15 parts by weight, more preferably about 2 to 12 parts by weight, and most preferably 5 to 10 parts by weight, based on 100 parts by weight of cumene hydroperoxide stream. When the amount of the noble metal catalyst is less than about 1 part by weight, there is a problem that the conversion rate is lowered, and when it exceeds about 15 parts by weight, there is a problem that the selectivity is lowered.

  The hydrogenation reaction is preferably performed at a temperature of about 40 to 80 ° C. and a hydrogen flow rate of about 1: 1 to about 1:10 depending on the molar ratio of CHP to about 1 to 5 hours. The hydrogenation reaction may be carried out under normal fluid space velocity conditions.

  The hydrogenation reaction may be performed by adding about 1 to 10 moles of hydrogen to 1 mole of cumene hydroperoxide. At this time, if the number of moles of hydrogen added is less than about 1 mole, there is a problem that the conversion rate and selectivity decrease, and if it exceeds about 10 moles, an excessive amount of hydrogen must be recycled. There may be a problem with sex.

  Since the hydrogenation process of cumene hydroperoxide proceeds at a low concentration and a low temperature as in step (b), the present invention reduces the risk of explosion at the runway reaction temperature of cumene hydroperoxide and is maximally stable. The conversion rate to cumyl alcohol can be increased under converted conditions. Further, cumene hydroperoxide at a high concentration is converted to cumyl alcohol, the content thereof is increased, and the content of α-methylstyrene can be increased in the subsequent steps. The selectivity of the hydrogenation reaction may be about 90% or more, more preferably about 95% or more. That is, in the case of catalyst reduction used in the past, the conversion rate is about 20 to 35%, the selectivity is about 80%, and the maximum yield is not about 40%. The hydrogenation process can yield cumyl alcohol with a conversion of about 95% or higher, a selectivity of about 95% or higher, and a yield of about 90% or higher. In addition, in the hydrogenation step, cumene mixed with cumene hydroperoxide is also partially converted to cumyl alcohol, and additional yield improvement can be expected.

  The step (c) is a process for producing α-methylstyrene using cumyl alcohol. At this time, in the step (c), the reactant containing the cumyl alcohol further includes a cumene hydroperoxide stream that does not undergo the hydrogenation reaction. Accordingly, the product including α-methylstyrene further includes phenol and acetone together with α-methylstyrene through the dehydration reaction of the reactant. Preferably, the phenol and acetone are produced by a dehydration step after the cumene hydroperoxide stream in the reactants has contacted the acid catalyst. Moreover, alpha methyl styrene is produced | generated by a dehydration process, after the cumyl alcohol in a reaction material contacts an acid catalyst. The product further includes trace amounts of acetophenone, cumene, and heavy compounds.

  The reaction product containing cumyl alcohol is concentrated to a concentration of about 80 to 82% by weight and used for the dehydration reaction.

  In the case of the present invention, in order to minimize the production of intermediate compounds as necessary, before performing the step (c), the cumene hydroperoxide stream used in the hydrogenation reaction of the step (b) is removed. It is also possible to dilute the mixture of the remaining stream residues and the cumyl alcohol obtained in step (b).

  In the step (c), the acid catalyst is preferably a liquid or solid acid catalyst. The liquid acid catalyst is hydrochloric acid, sulfuric acid or nitric acid, and preferably sulfuric acid may be used. The solid acid catalyst includes a group 4 metal oxide modified by a group 6 metal oxide, a sulfated transition metal oxide, a metal oxide mixed with cerium oxide and a group 4 metal oxide, and these Preferably, it is selected from the group consisting of:

  Further, the present invention further includes a step of neutralizing and distilling the product containing α-methylstyrene after step (c). Through such a process, α-methylstyrene, phenol and acetone are separated.

  The distillation conditions are not particularly limited, and are performed by an ordinary method. In the neutralization step, the type and content of the neutralizing agent are not particularly limited and can be used under normal conditions.

  Hereinafter, a method for producing α-methylstyrene according to a preferred embodiment of the present invention will be described more specifically with reference to the drawings. FIG. 2 is a simplified diagram showing a phenol process for producing α-methylstyrene of the present invention.

  Referring to FIG. 2, the method of the present invention includes an oxidation reactor 10 for proceeding the oxidation of cumene, and a hydrogenation reaction for using a part of the cumene hydroperoxide stream obtained after the oxidation for the hydrogenation reaction. A hydrogenation reactor 30, a stripper 40 for concentrating the cumyl alcohol obtained in the hydrogenation reaction and the remaining cumene hydroperoxide stream not used in the hydrogenation reaction, concentrated in the stripper A decomposition reactor 60 for proceeding with the dehydration reaction of the mixture, a neutralization reactor 70 for proceeding with the neutralization of the product obtained by the dehydration reaction, and a distillation for separating the product Proceed with apparatus 80. Receivers 20 and 50 are provided between the oxidation reactor 10 and the stripper 40 and between the stripper 40 and the decomposition reactor 60.

  Specifically, the present invention provides a cumene hydroperoxide and cumyl alcohol having a low concentration in the oxidation of cumene, and immediately hydrogenating the cumene hydroperoxide without concentrating the cumene hydroperoxide. And preparing a reactant containing cumyl alcohol by mixing the remaining cumene hydroperoxide residue not used in the hydrogenation reaction with cumyl alcohol obtained by the hydrogenation reaction, Is subjected to a dehydration reaction in the presence of an acid catalyst, whereby a product containing α-methylstyrene with increased productivity can be obtained. Since the product contains both phenol and acetone, after the step, the product is neutralized and distilled to obtain AMS with increased productivity together with phenol and acetone. . Therefore, through the selective hydrogenation process of cumene hydroperoxide, the conversion rate of cumene hydroperoxide to cumyl alcohol can be improved from the existing one, and the content thereof can be increased or decreased. The amount can also be increased or decreased.

  That is, according to the present invention, cumene is supplied to the oxidation reactor 10 and the oxidation reaction of cumene proceeds in the presence of oxygen. Oxidation of the cumene produces a cumene hydroperoxide stream at a concentration of about 5 to 25% by weight, preferably about 10 to 25% by weight, most preferably about 20 to 25% by weight. Contains alcohol.

  Thereafter, according to the present invention, a part of the stream is separated and transferred to the reservoir 20 and then supplied to the hydrogenation reactor 30 to advance the hydrogenation reaction. At this time, the low-concentration cumene hydroperoxide stream transferred to the reservoir 20 is supplied to the top-down or bottom-up of the catalytic hydrogenation reactor 30, and cumylated by the hydrogenation reaction. Produce alcohol. The reactor used for the hydrogenation reaction can be advanced by a CSTR reactor (Continuous straight-tank reactor), but is not limited thereto, and any reactor can be used as long as it is used for normal hydrogenation reaction conditions. Can also be used. For example, the hydrogenation reactor is preferably filled with a catalyst, and it is preferable to inject hydrogen and proceed the reaction so that the internal temperature is maintained. In addition, the concentrated cumene hydroperoxide stream, which is the reactant, can be injected into the upper stage of the reactor using a pressure pump.

  When the hydrogenation reaction is completed, the produced cumyl alcohol is supplied to the reservoir 20 again and transferred to the stripper 40 through this. Also, the CHP stream having a concentration of 5 to 25% by weight that does not proceed to the hydrogenation reaction is immediately transferred to the stripper 40.

  Thereby, the stripper 40 contains a mixture of cumyl alcohol obtained by the hydrogenation reaction and a stream containing cumyl alcohol and cumene hydroperoxide not used in the hydrogenation reaction.

  Thereafter, the stripper 40 concentrates the mixture to a concentration of about 80 to 82% by weight, and then transfers the mixture to the decomposition reactor 60 via the reservoir 50.

  Thereafter, the mixture is continuously dehydrated in the decomposition reactor 60 so that the acidic catalyst decomposes cumene hydroperoxide into phenol and acetone and dehydrates cumyl alcohol into AMS.

  Further, the mixture of phenol, acetone and AMS produced in the decomposition reactor 60 is transferred to the neutralization reactor 70, where a neutralizing agent is added to proceed with the neutralization reaction.

  Finally, the product is transferred to the distillation apparatus 80 and separated into phenol, acetone and AMS, respectively, by distillation.

  At this time, in the present invention, the conditions of the reactor used for each reaction step are not particularly limited, and ordinary reactors well known in this field can be used. Each reactor can be connected through a separate transfer line. Further, phenol, acetone and AMS that are finally separated are collected in a collection storage tank through a separate outlet.

  The present invention proceeds with the hydrogenation reaction of cumene hydroperoxide obtained in the oxidation of cumene under the maximum stabilized conditions at low concentration and low temperature, and is more stable without the danger of cumene hydroperoxide explosion. Cumyl alcohol can be produced in the state. In addition, the present invention increases the production of AMS in a phenol plant by converting cumene hydroperoxide to cumyl alcohol with high selectivity through the hydrogenation process, and cumene hydroperoxide injected into the hydrogenation process. By controlling the amount of streams, AMS production can be controlled according to market demand.

It is process drawing which shows the conventional phenol manufacturing process simply. The phenol process diagram for producing the alpha methyl styrene of this invention is shown simply.

  Hereinafter, the operation and effect of the present invention will be described in more detail with reference to specific examples of the present invention. However, such embodiments are merely presented as examples of the invention, and do not define the scope of rights of the present invention.

[Examples 1 and 2]
Α-methylstyrene was produced according to the process diagram shown in FIG.

  First, using three oxidation reactors in the phenol process, the oxidation of cumene using an oxidant proceeded under the following conditions to produce a stream containing 25% by weight of cumene hydroperoxide (CHP).

(1) Conditions for charging first oxidizer Supply (CHP 0.4% + cumene 99.6%) 1 ml / min, 02: 100 ml / min, pressure: 3 bar, reaction temperature: 100 ° C.
(2) Conditions for charging the second oxidizer (second oxidizer) Supply (CHP 8.42% + cumene 91.58%) 1 ml / min, 02: 100 ml / min, pressure: 3 bar, reaction temperature: 96 ° C.
(3) Conditions for charging a third oxidizer Supply (CHP 16.27% + cumene 83.73%) 1 ml / min, 02: 100 ml / min, pressure: 3 bar, reaction temperature: 94 ° C.
At this time, the concentration of the CHP stream was changed to 8.4 to 24% by weight through three oxidation reactors as shown in Table 1 below.

  Thereafter, 25% by weight of the low-concentration stream was separated and transferred to the reservoir 20 and then supplied to the catalytic hydrogenation reactor 30.

  In the hydrogenation reactor, Pd / C was filled with a catalyst, hydrogen was injected, and the reaction proceeded to maintain the internal temperature. Moreover, the 25 wt% concentration cumene hydroperoxide stream as the reactant was injected into the top-down of the reactor using a pressure pump. The hydrogenation reaction proceeded under conditions of 150 g of cumene hydroperoxide (CHP) having a concentration of 25% by weight, 1 g of Pd / C of 1% by weight, and a hydrogen flow rate of 150 cc / min. In addition, the molar ratio of cumene hydroperoxide stream to hydrogen input was maintained at 1: 8. The hydrogenation reaction time proceeded in 7 hours and 3 hours, respectively, to be Examples 1 and 2. As a result, a final product having a cumene hydroperoxide (CHP) conversion rate of 99.97%, a CA increase rate of 960.5%, and a CA concentration of 25% was obtained.

  After completion of the reaction, the conversion rate of cumene hydroperoxide to cumyl alcohol was analyzed by liquid chromatography, and the results are shown in Table 2.

  When the hydrogenation reaction was completed, the produced cumyl alcohol was supplied to the reservoir 20 and transferred to the stripper 40 through this. Thus, the stripper 40 is filled with a mixture of cumyl alcohol obtained in the hydrogenation reaction and a stream containing cumyl alcohol and cumene hydroperoxide not used in the hydrogenation reaction.

  Thereafter, the mixture was concentrated by the stripper 40, transferred to the cracking reactor 60 through the reservoir 50, and the rest was immediately transferred to the cracking reactor.

  Thereafter, an acid catalyst is added to the decomposition reactor 60, and the mixture is continuously dehydrated. The acidic catalyst decomposes cumene hydroperoxide into phenol and acetone, and cumyl alcohol is dehydrated into AMS. I made it.

At this time, 100 g of feed (CHP 72% by weight, CA 8% by weight, cumene 20% by weight) and 1 g of H ₂ SO ₄ were put into the cracking reactor to proceed the reaction. The reaction temperature was maintained at 65 ° C., and the CHP concentration was converted to less than 1%, and then the temperature was increased to 110 ° C. to convert CA to AMS.

  The mixture of phenol, acetone and AMS produced in the decomposition reactor 60 was transferred to the neutralization reactor 70, where a neutralizing agent was added to proceed with the neutralization reaction. After neutralization, the product was transferred to a distillation reactor 80 and separated into phenol, AMS and acetone, respectively, by distillation.

According to the above reaction, the yield was 99.36% when CHP was converted to phenol, the yield was 98.30% when CHP was converted to acetone, and the yield was 82.45% when CA was converted to AMS.

In Table 1, in 1 ^st decomposition reactor, the majority of the CHP is decomposed into phenol and acetone, the concentration showed that decreases from 82 wt% to 1 wt%, with 2 ^nd decomposition reactor, 1 weight % CHP was reduced to 1% by weight or less.

[Comparative Examples 1 and 2]
The reduction reaction proceeds without hydrogen using 150 g of the prepared 25 wt% cumene hydroperoxide and 1 g of Co / Al / PO ₄ (Co: 7 wt%, Al: 25 wt%, P: 3 wt%) catalyst. Thus, cumyl alcohol was produced. The reaction times were 7 hours and 3 hours, respectively, and Comparative Examples 1 and 2 were used.

  In addition, other conditions proceeded in the same manner as in Example 1 to produce AMS. The results of the conversion rate of cumene hydroperoxide and the increase rate of cumyl alcohol are shown in Table 2.

[Comparative Examples 3 to 4]
50 g of 80% strength cumene hydroperoxide concentrated through cumene oxidation reaction and stripper was diluted to 100 g of acetone, and the hydrogenation reaction did not proceed. Mill alcohol was produced. The results of the conversion rate of cumene hydroperoxide and the increase rate of cumyl alcohol are shown in Table 2.

  From the results in Table 2 above, Examples 1 and 2 of the present invention are compared to Comparative Examples 1 to 4 by using a 25 wt% CHP solution exiting the oxidation reactor as the feed for the hydrogenation reaction. The conversion rate of cumene hydroperoxide (CHP) was excellent, and the production amount of cumyl alcohol was increased. Further, in the production of phenol, acetone and α-methylstyrene by dehydration using cumyl alcohol, in the case of Example 1-2 of the present invention, the production amount of AMS is 100 to 1200% as compared with Comparative Example 1-4. Increased to a degree.

[Experimental example]
In Example 1 above, after the addition of CHP during the hydrogenation step was completed, the composition of the reactant solution was analyzed over time. By such composition analysis, the CHP conversion rate and the CA increase rate in the catalytic hydrogenation step were measured by the following methods, and the results are shown in Table 3.

[Formula 1]
CHP
Conversion (%) = (CHP feed (wt%)-CHP product (wt%)) / (CHP feed (wt%))

[Formula 2]
CA increase rate (%) = (CA product (wt%)-CA feed (wt%)) / (CA feed (wt%))

1,10 Oxidation reactor 2,4,20,50 Receiver
30 Catalytic hydrogenation reactor
3,40 stripper
5,60 Cleavage reactor
6,70 neutralizer reactor
7,80 Distillation equipment

Claims (16)

A method for producing α-methylstyrene,
(A) oxidizing cumene to produce a cumene hydroperoxide stream;
(B) separating at least a portion of the cumene hydroperoxide stream without concentrating and selectively hydrogenating it under a noble metal catalyst to produce cumyl alcohol;
(C) concentrating the reaction product containing cumyl alcohol and subjecting it to a dehydration reaction in the presence of an acid catalyst to produce a product containing α-methylstyrene, Production method.   The method for producing α-methylstyrene according to claim 1, wherein the cumene hydroperoxide stream is used in the hydrogenation reaction at a concentration of 5 to 25 wt% in the step (b).   2. The method for producing α-methylstyrene according to claim 1, wherein in the step (b), 5 to 50 wt% of the cumene hydroperoxide stream is separated and used for the hydrogenation reaction.   The said noble metal catalyst contains 1 or more types selected from the group which consists of gold | metal | money, silver, platinum, palladium, iridium, ruthenium, rhenium, rhodium, and osmium, The any one of Claims 1-3 characterized by the above-mentioned. A process for producing α-methylstyrene as described in 1. above.   The noble metal catalyst additionally comprises a support selected from the group consisting of alumina, silica, clay, carbon, zirconia, titania, mesoporous molecular sieves and mixtures thereof. 4. The method for producing α-methylstyrene according to 4.   The method for producing α-methylstyrene according to any one of claims 1 to 5, wherein the noble metal catalyst is used in an amount of 1 to 15 parts by weight with respect to 100 parts by weight of cumene hydroperoxide stream.   The hydrogenation reaction is performed for 1 to 5 hours at a temperature of 40 to 80 ° C and a hydrogen flow rate of 1: 1 to 1:10 depending on a molar ratio of cumene hydroperoxide (CHP). The method for producing α-methylstyrene according to any one of 6.   The method for producing α-methylstyrene according to any one of claims 1 to 7, wherein the selectivity of the hydrogenation reaction is 95% or more.   The method for producing α-methylstyrene according to any one of claims 1 to 8, wherein the conversion rate of cumene hydroperoxide is 95% or more.   The method for producing α-methylstyrene according to claim 1, wherein the cumene hydroperoxide stream further contains cumyl alcohol.   The method for producing α-methylstyrene according to claim 1, wherein the acid catalyst is a liquid or solid acid catalyst. The liquid acid catalyst is hydrochloric acid, sulfuric acid or nitric acid;
The solid acid catalyst is a group 4 metal oxide modified with a group 6 metal oxide, a sulfated transition metal oxide, a mixed metal oxide of cerium oxide and a group 4 metal oxide, and these The method for producing α-methylstyrene according to claim 11, wherein the method is selected from the group consisting of a mixture. In the step (b), a hydrogenation reaction proceeds on a part of the cumene hydroperoxide stream,
In the step (c), the reactant containing the cumyl alcohol further includes a cumene hydroperoxide stream that does not undergo the hydrogenation reaction. A method for producing α-methylstyrene.   The method for producing α-methylstyrene according to any one of claims 1 to 13, wherein in the step (c), the product containing α-methylstyrene further contains phenol and acetone.   The production of α-methylstyrene according to any one of claims 1 to 14, wherein the reaction product containing cumyl alcohol is concentrated to a concentration of 80 to 82% by weight and used in a dehydration reaction. Method.   The method for producing α-methylstyrene according to claim 1, further comprising a step of neutralizing and distilling the product containing α-methylstyrene after the step (c).

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