KR100321518B1 - PROCESS FOR RECOVERING PHENOL, CUMENE AND α-METHYL STYRENE FROM BYPRODUCT OF PHENOL PRODUCING PROCESS, AND THE APPARATUS THEREOF - Google Patents

Abstract

In a device equipped with a known feed pump (1), nitrogen gas (2), reactor (3), heater (5), thermometer (4), (6), condenser (8), and valve (10), the reactor In the lower part of (3), a drain (7) is provided, and a phenol, cumene, α is decomposed by decomposing a mixture of aromatic compounds obtained as a by-product in the phenol production process consisting of a cage (C) made of a stainless steel mesh supporting a catalyst in the reactor. A device for recovering methyl styrene and a mixture of aromatic compounds obtained as a by-product from the phenol production process are decomposed and reacted at 200 to 300 DEG C while removing high-boiling substances in the reactants through a lower drain in the presence of an alumina catalyst. Disclosed is a process for the recovery of phenol, cumene, α -methylstyrene, characterized in that the product is continuously removed via a distillation and the reactants are continuously fed using a pump.

Description

Recovery of phenol, cumene, α-methylstyrene from phenol by-products and its apparatus {PROCESS FOR RECOVERING PHENOL, CUMENE AND α-METHYL STYRENE FROM BYPRODUCT OF PHENOL PRODUCING PROCESS, AND THE APPARATUS THEREOF}

The present invention relates to a method for recovering phenol, cumene and α -methylstyrene by decomposing a mixture of aromatic compounds obtained as a byproduct in a phenol production process, and an apparatus for carrying out the method.

In the process of producing phenol through cumene made by reacting benzene and propylene, a mixture of aromatic compounds containing cumylphenol and α -methylstyrene dimer, in addition to the main products phenol and acetone is obtained as a by-product. In the acid catalyst cumylphenol can be broken down to cumene and phenol, and the α -methylstyrene dimer can be broken down to α -methylstyrene. Cumene is an intermediate in the phenol production process, phenol is the desired product and α -methylstyrene is a high value added substance. Therefore, if the cumylphenol and α -methylstyrene dimer contained in the by-products can be decomposed and recovered into cumene, phenol and α -methylstyrene, the economic value of the by-products can be increased.

However, by-products of the phenol manufacturing process currently undergoing cumene are used as fuel or further distilled to recover a portion of the active ingredient. These by-products contain a lot of aromatics, so it is difficult to completely burn them, and the use of fuel as a fuel requires facility investment and operating expenses to reduce the emission of aromatics to within acceptable levels. In view of this, it is reasonable to decompose the by-products into cumene, phenol and α -methylstyrene using a catalyst to recover the most economically valuable materials, and then use the residual materials as raw materials for the production of carbonaceous materials. .

In the reaction for decomposing the substituted functional group in the aromatic ring, an acid catalyst which provides a proton to promote decomposition of the carbon-carbon bond may be used. On the other hand, a base catalyst capable of accepting protons is effective in decomposing a carbon chain substituted in an aromatic ring. Cumylphenol has a structure in which cumene is bonded to phenol, and hydrogen molecules are removed during condensation. Thus, cumene phenol and α -methylstyrene are produced when decomposed in an acid catalyst. α -methylstyrene dimers can easily break the carbon chain in base catalysts that can accept protons from hydrocarbons because the end carbons of the styrene polymerized to form dimers. As such, the catalyst that can be used for the decomposition reaction of cumylphenol and α -methylstyrene, which are the main components of the by-product of the phenol manufacturing process, is different from acid and base, so it is not easy to design an appropriate catalyst.

Decomposition of an aromatic compound with an acid catalyst in the gaseous phase leads to various reactions such as cracking, dealkylation, and isomerization, resulting in a large number of products, resulting in poor economic efficiency. Decomposition at as low a temperature as possible or liquid phase decomposition is preferred. However, when the decomposition reaction proceeds in the liquid phase, the concentrated aromatic compound and the catalyst come into contact with each other. Therefore, since the aromatic compound polymerizes on the surface of the catalyst and precipitates as carbon, the activity decrease is very fast. Therefore, the catalyst that can be used for the decomposition reaction of the by-product of the phenol production process should be able to suppress the deactivation due to carbon precipitation while the pores are large so that aromatic compounds can be rapidly diffused. In general, when the acid strength or base strength is high and the activity is large, the product per unit mass of the catalyst increases. However, the selectivity must be high so that the activity is high and no secondary by-products are produced. This is because, in the process of treating by-products and recovering them as useful resources, the product should be simple to increase its economic value.

In general, since the by-products contain small amounts of various substances, the added value of the process of processing and refining them cannot be higher than the process by which the by-products are produced. Therefore, if the by-products are processed using expensive catalysts made of expensive materials such as precious metals, the economic benefits are low. Therefore, cheap and easy to use catalysts should be used. In this regard, the design of catalysts for the recycling of by-products is very difficult and has many limitations, so there are not many commercialized examples. If by-products can be treated by fuel or by other means, economical catalyst production is difficult and does not require the use of catalysts to resourceize them.

Aromatic compounds are important raw materials in the petrochemical industry, and cumene and alpha -methyl styrene have high added value. Attempts to recover and resource them from phenol production by-products, which are mixtures of aromatic compounds, are highly desirable in terms of improving the economic value of the by-products and effective resource utilization. In addition, an easy-to-handle atmospheric liquid phase reaction effectively decomposes the by-products of the phenol process to produce cumene, phenol, and α -methylstyrene. Furthermore, since an effective catalyst is developed and used, it is economically valuable to maximize the yield of the desired product at low temperatures without producing secondary byproducts.

The present inventors earnestly studied to achieve the above object, and as a result, by supplying by-products at a constant rate, the decomposition products were continuously recovered through a distillation machine, and the catalyst layer was lifted slightly from the bottom so that the unboiled high-boiling reactants did not come into contact with the catalyst. By using a reactor in the form of a reactor, by using a weakly acidic or weakly alkaline alumina catalyst having alumina content of not less than 70% and a surface area of not less than 50 m 2 / g as a catalyst, and having a g or h type crystal structure, as a by-product in the phenol manufacturing process It was found that the mixture of the obtained aromatic compounds can be effectively decomposed to be recovered with phenol, cumene and α -methylstyrene, thereby completing the present invention.

That is, an object of the present invention is to provide a method and apparatus for recovering phenol, cumene, α -methylstyrene by effectively decomposing a mixture of aromatic compounds obtained as by-products in the phenol production process.

1 is a schematic diagram of a continuous process apparatus of a phenol manufacturing process by-product according to the method of the present invention.

A feature of the present invention for achieving the above object is to effectively decompose the mixture of the aromatic compound obtained as a by-product in the phenol production process using the apparatus of Figure 1 attached to recover the phenol, cumene, α -methylstyrene.

In FIG. 1, the feed pump 1, the nitrogen gas 2, the reactor 3, the heater 5, the thermometers 4, 6, the condenser 8, and the valve 10 are known devices. The present invention is characterized in that the drain (7) is installed in the lower part of the reactor (3) to discharge the high-boiling matter collected under the reactor, and also the cage (C) made of stainless steel mesh in the reactor. The cage contains a catalyst for decomposition reaction. The cage is located away from the bottom of the reactor to prevent contact with high-boiling materials so that the catalyst in the cage can be in contact with the high-boiling reactants to prevent degradation of activity due to carbon precipitation.

Hereinafter, the reactor for continuous operation with a distillation machine is demonstrated.

The by-products of the phenol production process contain cumylphenol, α -methylstyrene dimer, and acetophenone, which can be decomposed or recovered by a multi-stage distillation method such as reduced pressure, and high boiling point materials that are difficult to be separated by distillation. Therefore, in a reactor using a catalyst, a removal valve is installed to remove the high boiling point material which is not decomposed and can discharge the high boiling point material at an appropriate time interval. In addition, α -methylstyrene, which is a decomposition product, is further converted from acid catalysts to various indene materials, and therefore, they must be removed continuously. This can increase the process efficiency and simplify the operation, allowing continuous operation of the disassembly process. When the catalyst is in contact with the high-boiling reactant, the activity is reduced by carbon precipitation, so that the catalyst may be in contact with the by-product, but separated from the collected high-boiling material.

A small amount of nitrogen gas was flowed into the reactor to suppress side reactions caused by oxygen. The catalyst was placed in a basket made of stainless steel mesh and contacted with the byproduct by fixing it at a predetermined height below, for example, depending on the reactor, but about 5 to 10 cm high for a 1 L reactor. Initially, the appropriate amount of by-product is added to start the decomposition reaction, and at the same time, the by-product is continuously supplied to the pump. The decomposed product is also recovered continuously through a distillation machine. The high boiling point material collected at the bottom of the reactor is discharged every 10 minutes in the case of a 1 L reactor, so as not to directly contact the catalyst layer to lower the activity of the catalyst. As shown in the examples, active ingredients of by-products such as cumylphenol and α -methylstyrene dimer are decomposed in an alumina catalyst and recovered through a distillation unit.

Hereinafter, the catalyst for decomposing by-products of the phenol production process will be described.

Cumylphenol and α -methylstyrene dimers, which are the main components that can be catalytically decomposed in the phenol production by-products, will be decomposed in acid or base catalysts. In practice, in strong acid or base catalysts, they interact strongly with the catalyst and are deposited as carbon, so the activity of the catalyst is rapidly lowered and their decomposition reactions rarely proceed. Rather, the acid strength is weak, but the decomposition activity is high in the catalyst having many acid points. If the porosity is too small and the diffusion of the aromatic material is slow, only the outer surface participates in the decomposition reaction and is slow. However, in the mesoporous material with a certain pore size, the reaction of converting the α -methylstyrene into indene or the like proceeds. Thus, the acid strength is not too strong, but the pores are large enough so that the product diffuses quickly so that the product does not concentrate in the pores.

Alumina is a catalyst that satisfies the requirements of the catalyst that can be used to decompose by-products of the phenol production process. Alumina is a very weak acid catalyst, but depending on the firing conditions, a very weak base may be produced. At the same time, since the pores are very large as compared to zeolite or mesoporous materials as amorphous catalysts, there is little possibility of intra-pore concentration and further reaction of decomposition products. On the other hand, at a weak acid point generated during the dehydration of the alumina surface, cumylphenol is decomposed into phenol and α -methylstyrene in equivalent proportion. Therefore, if alumina is used, there is no fear of generating secondary byproducts. Increasing the amount of catalyst used increases the conversion rate of the decomposition reaction without loss of selectivity. The alumina catalyst is also active in the decomposition reaction of α -methylstyrene dimer in addition to cumylphenol. Alumina is very suitable for the decomposition of by-products in the process of phenol production because of the high acidity, the decomposition reaction is fast, the pores are large, and the material transfer speed is fast.

Supporting a small amount of lithium oxide on the alumina enhances the base point to enhance catalyst activity and life. The base point is formed by the addition of lithium, and it is believed that the catalytic activity is enhanced by the synergy of acid and base points.

EXAMPLE

Hereinafter, an Example is given and this invention is demonstrated concretely.

Composition of by-products

In the phenol production process, different by-products are produced in the cumene production step and in the production of phenol from cumene and oxide. By-products in the cumene production step are many aromatic compounds in which two isopropyl groups are substituted, and a catalytic process of converting the cumene into cumene and recycling it is well known. The by-product of the phenol production process mentioned in the present invention is a mixture produced in the step where cumene peroxide is decomposed into phenol and acetone. The main components are cumylphenol, α -methylstyrene dimer, acetophenol and the like. Table 1 summarizes representative compositions of by-products obtained in the phenol peroxide decomposition step of the process for producing phenol by cumene method. Although slightly different depending on the process operating conditions, only 60% of cumyl phenol, α -methylstyrene dimer and phenol which can be decomposed is added. Including acetophenone, 75% of the material can be recovered as a liquid during decomposition.

TABLE 1

Preparation of the catalyst

Table 2 lists the catalyst properties and the place of purchase, such as the Si / Al molar ratio and surface area of the zeolite catalysts used (FER, MFI, MOR, FAU, BEA), KIT-1 mesoporous material and amorphous catalysts (silica-alumina, alumina).

MFI zeolite is made of colloidal silica (Du Pont, Ludox HS-40, 40%), aluminum hydroxide (Junsei, CP grade) sodium hydroxide (Tedia,> 95%) and tetrapropylammonium bromide (Fluka,> 98%) One reaction mother liquor was synthesized by hydrothermal reaction at 175 ° C. for 7 days (see Z. Gabelica, EG Derocane and N. Blom ACS Symp. Ser., 218 (1984) 219).

TABLE 2

a) W. M. Meiner, H. H. Olson and Ch. Baerlocher, 'Atlas of Zeolite Structure Types', 1996

All zeolites were ion-exchanged at 80 ° C. for 24 hours with 1N ammonium nitrate (Fluka, GR> 99%) solution, and then calcined at 550 ° C. for 12 hours to make H-type.

KIT-1 mesoporous material was described by Ryoo et al. [R. Ryoo, J. M. Kim, C. H. Ko and S. H. Shin, J. Phys. Chem., 100 (1996) 17718]. While stirring a mixture of hexadecanetrimethylammonium chloride (Aldrich, 25 wt%) and an aqueous ammonia solution, a solution of colloidal silica (Du Pont, Ludox HS-40, 40%) was dissolved in 1N aqueous sodium hydroxide solution. Slowly added. Subsequently, an appropriate amount of aqueous sodium aluminate (Junsei, 80%) solution was slowly added, and then the synthetic mother liquor was put in a 98 ° C. dryer for hydrothermal reaction. Synthesized KIT-1 material was filtered and washed with distilled water and dried in a 100 ℃ dryer for one day. After heating up to 550 degreeC in nitrogen at 1 degree-C / min, calcining in air for 8 hours, and ion-exchanging by the same method as MFI zeolite, the H-type KIT-1 catalyst was prepared.

Decomposition of By-Products in Zeolite Catalysts

Catalytic cracking of the by-products of the phenol process using zeolite catalysts in a liquid phase reactor equipped with a reflux condenser decomposes cumylphenol and α -methylstyrene dimer, but the decomposition yield is not very high. Some of the resulting α -methylstyrene is further reacted and converted into high boiling compounds such as indene. Table 3 summarizes the product composition of the by-product decomposition reaction using MFI, FAU, and BEA zeolite catalysts. The numbers in the parentheses of the zeolite indicate the Si / Al molar ratio of the zeolite, and the smaller the Si / Al molar ratio, the more acid points. The high boiling point material not analyzed in the product was removed and only the components dissolved in the ether were analyzed. There is no difference in the product composition even if the zeolite type is changed or the amount of the BEA (12) catalyst used is changed. Aromatic compounds not only rapidly lowered the activity of the catalyst but also produced secondary by-products with low added value such as indene, and it was determined that catalytic decomposition of the phenol production process by-products was difficult in a batch reactor equipped with a reflux cooler.

TABLE 3

^* Α - methylstyrene

^* Reaction condition: 40g of reactant, 240 ℃ in nitrogen stream

Decomposition of By-Products in a Reactor with a Distiller

In order to suppress the conversion of the resulting α -methylstyrene to indene and the like, and to increase the decomposition yield of the by-products, a distillator was installed to separate the product continuously during the reaction. Instead of installing a reflux condenser in the reactor, a distillator is installed to exclude cumylphenol, α -methylstyrene, dimer, indene, etc., which are not distilled at 300 ℃ or higher, and low boiling point phenol, cumene, α -methylstyrene, acetophenone Was recovered. By directly recovering the low boiling point of the active product, it was possible to promote the decomposition reaction and to suppress the further reaction. Table 4 summarizes the decomposition results of the by-products of the phenol production process, which were investigated in a reactor equipped with distillers using several types of catalysts.

TABLE 4

^* Rate of reaction of the product obtained after the retort.

^** Pyrolysis without catalyst.

In Li-FAU (3) or Cs-FAU (3) catalysts, the decomposition yield was lower than that of pyrolysis. The acidic catalyst and the H-BEA (12) catalyst had higher yields than the pyrolysis, but the activity was very low like the base catalyst because the difference was not large. In comparison, Li-KIT1 (20) catalyst, which is slightly basic, has high decomposition activity and yields as high as 33% when 0.2 g is used. When 0.6 g of this catalyst is used, the yield is 56%, resulting in a large amount of phenol and α -methylstyrene. In this context, weakly acidic alumina was highly active as a catalyst of the phenol production by-product. Using 1.0 g, the yield is 60%, which is quite close to the maximum expected yield of 75%. Increasing the amount of alumina catalyst to 3.0 g yielded 76% yield of decomposition products, allowing the recovery of all degradable or recoverable components in the by-products of the phenol production process. Higher catalyst usage up to 5.0 g did not result in higher yields of cracked products.

Higher catalyst usage results in lower economic value due to catalyst price and treatment costs. In order to overcome this problem, the amount of reactants that can be treated with the catalyst can be used for a long time, so the decomposition reaction of the by-products was investigated by repeatedly using the catalyst. Table 5 summarizes the yields of the products obtained upon repeated use of the catalyst. The yield varies slightly depending on the frequency of use, but overall the yield is very high, around 75%. As the catalyst was used sufficiently, a decrease in yield due to deactivation was not observed. The alumina catalyst was weakly acidic, so the carbon deterioration was not severe and the activity deterioration was slow. On the other hand, it was determined that alumina could be used as an industrial catalyst in the decomposition process due to high decomposition yield.

TABLE 5

Decomposition of By-Products in Reactors with Continuous Operation

In order to increase the efficiency of the process, a reactor capable of continuous operation is more effective than a batch reactor. By supplying by-products at a constant rate, the decomposition product was continuously recovered through a distillation machine, and a reactor having a slightly floated catalyst layer on the bottom was devised so that the non-decomposed high-boiling reactant was suppressed from contacting the catalyst (FIG. 1). The high-boiling unreacted material collected under the reactor is removed through the valve at regular intervals, allowing for continuous processing.

The operation details of the by-product of the phenol production process operated by the reactor capable of continuous operation are as follows.

Catalyst type and amount used: g -alumina 5g

Total by-product supply: 100 ml

By-product feed rate: 1 ml / min

Reactor temperature: 300 ℃

In a continuous process, a 65% cracking yield was obtained using an alumina catalyst, which is similar to a batch reactor. In addition, the catalytic activity was not significantly reduced even when 50 ml of the byproduct was treated with 1 g of alumina.

Properties of Alumina Catalyst

Various kinds of alumina were used to investigate the decomposition reaction of by-products of phenol manufacturing process. Most of the commercially available alumina catalysts were excellent in the decomposition reaction. Table 6 summarizes basic properties such as surface area of alumina, which had high activity.

TABLE 6

Decomposition of by-products in a reactor equipped with a reaction temperature of 300 ° C. and a distiller was carried out using 1 g of the other four kinds of aluminas shown in the table. Yields were 55%, 59%, 60% and 57%, respectively, similar to JRC-ALO-2 catalysts.

As described above, according to the method of the present invention, the aromatic compound obtained as a by-product in the phenol production process is easy to generate high-boiling hydrocarbons that cause deactivation with phenol, cumene, styrene, etc. In recovering phenol, cumene and α -methylstyrene by decomposing the catalyst supporting cage in the reactor so as to float in the reactants of the reactor so that the catalyst does not come into contact with the catalyst, the activity of the catalyst is increased, it can be used for a long time, and the decomposition The efficiency can be increased.

Claims (6)

In a device equipped with a known feed pump (1), nitrogen gas (2), reactor (3), heater (5), thermometer (4), (6), condenser (8), and valve (10), In the phenol manufacturing process consisting of a cage (C) made of a stainless steel mesh carrying a catalyst in the lower portion of the reactor 3, the drain (7) is provided to decompose the mixture of the aromatic compounds obtained as a by-product phenol, cumene, Recovery device for α -methylstyrene. The apparatus of claim 1 wherein the catalyst bearing cage is positioned to float in the reactants of the reactor. A mixture of aromatic compounds obtained as a by-product in the phenol production process using the apparatus of claim 1 is prepared in the presence of an alumina catalyst having an alumina content of at least 70%, a surface area of at least 50 m 2 / g and a crystal structure of g or h type. Phenol manufacturing process characterized in that the high boiling point material of the reactant is decomposed and reacted at 200 ~ 300 ℃ while removing through the lower drain so that the product is continuously removed through the distillation, the reactant is continuously supplied by using a pump To recover phenol, cumene, α -methylstyrene from by-products. delete The method according to claim 3, wherein a catalyst in which lithium or sodium oxide is supported on the alumina within 5% by weight is used. delete