KR100752418B1 - Catalyst for dehydrogenation of ethylbenzene for styrene conversion, preparation method thereof and preparation method of styrene monomer using the same - Google Patents

Abstract

The present invention relates to a catalyst for dehydrogenation of ethylbenzene for styrene conversion, a method for preparing the same, and a method for preparing a styrene monomer using the same. In particular, the present invention provides a catalyst for dehydrogenation of ethylbenzene for styrene conversion, including zirconium and titanium complex oxides, optionally manganese oxides, and optionally alkali or alkaline earth metal promoters, methods for their preparation and their presence in the presence of CO ₂ The present invention relates to a method for producing a styrene monomer by adding together with ethylbenzene and dehydrogenating ethylbenzene.

Accordingly, the present invention can eliminate the use of steam can not only save energy, but can also obtain styrene monomer with high yield and high selectivity.

Description

Catalyst for dehydrogenation of ethylbenzene for styrene conversion, preparation method thereof and preparation method of styrene monomer using the same {Catalysts for Dehydrogenation of Ethylbenzene into Styrene, Process Thereof and Preparation Method for Styrene Monomer Employing Them}

The present invention relates to a catalyst for dehydrogenation of ethylbenzene for styrene conversion, a method for preparing the same, and a method for preparing a styrene monomer. In particular, the present invention can eliminate the use of steam can not only save energy, but also a catalyst for dehydrogenation of ethylbenzene for styrene conversion, which is useful for the production of high yield and high selectivity of styrene monomer, a method for producing the same. And to a method for producing a styrene monomer using the same.

Styrene began to be mass produced industrially from ethylbenzene in the 1950s. This was possible due to the Fe ₂ O ₃ -Cr ₂ O ₃ -K ₂ CO ₃ based catalyst calcined at very high temperatures of 900 ° C. or higher as disclosed in US Pat. No. 2,461,147. The mechanical strength was good due to the high firing temperature, but the styrene selectivity was low.

In preparing polystyrene, styrene-butadiene rubber, acrylonitrile-butadiene-styrene, styrene-acrylonitrile and polyester resins, styrene is one of the commercially important chemicals.

Recently, styrene is produced by two processes. One process is by dehydrogenation of ethylbenzene and the other is by bonding reaction in the production process of propylene oxide. More than 90% of the styrene is produced by catalytic dehydrogenation of ethylbenzene with a potassium promoted iron oxide catalyst in the presence of excess dilution steam in a multi-layer insulator. The main disadvantages of this dehydrogenation reaction route of ethylbenzene are that it has high energy consumption, partial conversion, carbon deposition of catalysts and low selectivity.

In order to improve these existing commercial catalysts, various attempts have been made, such as changing catalyst components and promoters, or feeding oxygen and reaction pairs simultaneously. Of these reaction pairs with aniline, sulfur and nitrogen oxides showed increased activity due to the consumption of hydrogen produced in the dehydrogenation reaction, but produced sulfur and nitrogen oxides that were harmful to the environment. Recently, it has been found that the dehydrogenation reaction with the reverse-water-gas-shift reaction has additional advantages such as lowering the reaction temperature, increasing styrene selectivity, and prolonging the deactivation of the catalyst.

EP 0,335,130 and 1176916 disclose oxidative dehydrogenation of ethylbenzene with a complex oxide catalyst and an alkali promoted iron catalyst in the presence of oxygen, respectively. Although the conversion of ethylbenzene in the presence of oxygen was greatly increased, styrene selectivity was greatly reduced due to the by-product decomposition products and oxides.

Related examples of German Patent No. 1293805 disclose the promoting effect of ethylbenzene dehydrogenation reactions involving sulfur and sulfur oxides. The conversion and ethylen selectivity of ethylbenzene increased significantly, but environmental problems were inevitable.

Japanese Patent No. 3109335 Matsui et al. Disclosed that catalyst degradation was suppressed when CO ₂ and CO were supplied together with ethylbenzene.

Japanese Patent Laid-Open No. 2004-050111 Saito et al. Includes iron oxide (5-20% by weight), aluminum oxide (60-94% by weight) and yttrium oxide (1-20% by weight) which react with ethylbenzene in the presence of CO _2. An iron-based catalyst is disclosed. These catalysts showed better activity than commercial catalysts in the presence of CO ₂ .

A recent study (Studies in surface and catalysis 114, p. 415-418 (1998)) found that CO ₂ plays a very important role in the ethylbenzene dehydrogenation reaction with Fe / Ca / Al oxide catalysts. . The energy required to produce styrene following the dehydrogenation of ethylbenzene was 190 kcal / kg (styrene based) in the presence of CO ₂ (EB / CO ₂ = 1/9) and in the presence of steam (EB / H ₂ 0) at 1,500 kcal / kg (styrene). The amount of energy required for new processes using CO ₂ is much lower than that of current processes. This is mainly because large amounts of latent heat cannot be recovered in commercial processes by water condensation. Therefore, the dehydrogenation reaction in the presence of CO ₂ should be an energy saving process.

As described above, it is necessary to improve the dehydrogenation reaction process of ethylbenzene for styrene conversion. Therefore, it is preferable if it is a process which does not require steam. This is because a high energy input and a large amount of water must be recycled. It is further preferred if the process does not require oxygen as a simultaneous feed. This is because oxygen can be avoided from reacting with hydrocarbons or producing combustion products as products. Furthermore, it is even more desirable if the process is able to achieve satisfactory conversion of ethylbenzene and low selectivity for by-products, decomposition products and oxides.

Therefore, the present invention can eliminate the use of steam, and the dehydrogenation reaction catalyst of ethylbenzene for styrene conversion, which can achieve high efficiency of catalyst performance by environmentally friendly and economically harmless process by using CO ₂ in the reaction. It is an object of the present invention to provide a method for producing the styrene monomer using the same and a method for preparing the same.

In order to achieve the above technical problem, the present invention provides a catalyst for dehydrogenation of ethylbenzene for styrene conversion including zirconium and titanium complex oxides, optionally manganese oxides, and optionally alkali or alkaline earth metal promoters. .

In addition, the present invention comprises the steps of (a) dissolving at least two or more metal salts in zirconium salts, titanium salts and manganese salts in deionized water to form a composite metal hydroxide precipitate; And (b) selectively drying the metal hydroxide precipitates under reduced pressure filtration, and then calcining the same to provide a method for preparing a catalyst for dehydrogenation of ethylbenzene for styrene conversion.

The present invention also provides a method for preparing a styrene monomer, comprising the step of dehydrogenating the ethylbenzene by mixing the catalyst with ethylbenzene in the presence of a nitrogen stream or CO ₂ .

Hereinafter, the present invention will be described in detail.

The catalyst for dehydrogenation of ethylbenzene for styrene conversion according to the present invention includes binary or tertiary zirconium-based composite metal oxides. Preferably, the composite metal oxide is a catalyst composition comprising titanium / zirconium or manganese / zirconia or ternary composite metal oxides consisting of the metal oxides and optionally alkali or alkaline earth metal oxides as promoters.

In particular, in one configuration of the catalyst composition according to the present invention, the titania / zirconia composite oxide catalyst comprises 10-90 mol% zirconium oxide (ZrO ₂ ) and the balance titanium oxide (TiO ₂ ). Preferably 30-60 mole% zirconium oxide and the balance titanium oxide. This is because the conversion rate and styrene selectivity of ethylbenzene in the above range is greatly increased. At this time, when alkali metal or alkaline earth metal oxide is added as an accelerator, the preferred loading content is 1-10% by weight.

In the present invention, the catalyst composition includes 10-90 mol% of zirconium oxide and residual manganese oxide in the manganese / zirconia composite metal oxide catalyst. Preferred are 50-80 mole% zirconium oxide and residual manganese oxide. This is because the conversion rate and styrene selectivity of ethylbenzene in the above range is greatly increased. At this time, when alkali metal or alkaline earth metal oxide is added as an accelerator, the preferred loading content is 1-10% by weight.

In the present invention, the ternary titanium / manganese / zirconium composite metal oxide catalyst composition is 10 to 60 mol%, preferably 30 to 60 mol% zirconium oxide and 10 to 40 mol%, preferably 30 to 40 mol% Titanium oxide and residual manganese oxide (MnO ₂ ). This is because the conversion rate and styrene selectivity of ethylbenzene in the above range is greatly increased. At this time, when alkali metal or alkaline earth metal oxide is added as an accelerator, the preferred loading content is 1-10% by weight.

The zirconium-based composite metal oxide or solid solution which is a catalyst for dehydrogenation of ethylbenzene for styrene conversion according to the present invention may be prepared by a conventional process such as co-precipitation. An example of the manufacturing process by the coprecipitation method is as follows.

The first step of coprecipitation (a) comprises at least one soluble zirconium salt in an aqueous medium, such as a zirconium compound salt such as chlorides of zirconium, its chlorides and nitrides thereof, or mixtures thereof; Optionally at least one titanium salt, preferably titanium (IV) halogen compound salt; And optionally a mixture containing at least one manganese salt, such as a manganese salt of a halogen compound such as nitride of manganese or a chloride thereof, in deionized water.

The mixture can be obtained from a water soluble solid compound or directly from an aqueous solution of the compounds. In particular, in the case of titanium salts, it can be obtained by acid-decomposing anhydrous titanium (IV) chloride or directly from it. Preferably it is obtained by decomposing the titanium (IV) chloride in nitric acid.

The content of zirconium salt, optional titanium salt, and optional manganese salt contained in the mixture is substantially the stoichiometric ratio required to obtain the desired final composition. The zirconium salts, titanium salts and manganese salts are preferably used having a high purity, in particular about 99% or more.

These mixtures may contain one or more alkali metal or alkaline earth metal compounds as catalyst promoters. The catalyst promoter material can be added to the catalyst in various forms. For example, it may be added as an oxide, or may be added as another compound that can be converted to at least partial oxide in firing conditions. Hydroxides, carbonates, bicarbonates and the like are suitable. Among the suitable catalyst promoters, it is preferred to be present in the catalyst as a potassium compound, preferably potassium carbonate (K ₂ CO ₃ ), potassium oxide (K ₂ O), or mixtures thereof. The content is preferably 1 to 10% by weight based on the total composition.

Precipitation can be carried out by dissolution of these salt solutions with a basic solution or deionized water. At this time, the mixture may be vigorously stirred at room temperature or reacted at about 40 ° C. to 80 ° C. under atmospheric pressure to precipitate metal salts.

The basic solution is a hydrogenating agent added to improve the yield of the reaction, and non-limiting examples may be an ammonia solution or an alkali metal hydroxide solution such as potassium, sodium and the like. The basic solution which can be preferably used is an aqueous ammonia solution or an aqueous sodium or potassium hydroxide solution. It is more preferable to use ammonia solution among these. In the present invention, the normal concentration of the basic solution is not a critical factor, and its range is not limited.

Precipitation by this coprecipitation can be carried out as a series of processes. When a series of precipitation methods are used, the pH concentration of the reactants is usually adjusted to about 7-12, preferably about 7-9, in order to convert the metal salts into metal hydroxides. The residence time of the material in the reactor is at least about 30 minutes to 60 minutes. The reaction can be carried out at a suitable temperature such as room temperature. The optimum reactor temperature is maintained at about 60 ° C.

The reaction of the mixture thus prepared may be carried out in an open reactor under atmospheric pressure. This is because the pressure in the reactor can rise automatically when carried out in a closed reactor.

In step (b) after the precipitation reaction, the solid precipitate is recovered from the reactor and separated from the parent salt solution using known methods such as filtration, sedimentation or centrifugation. The precipitate obtained can then be washed selectively. If washing is performed, it may be washed at least five times with deionized water.

The process then optionally undergoes a drying step in the middle, and then the recovered precipitate is calcined. Generally, calcining is carried out at a temperature in the range of about 300 ° C to 800 ° C. Preferred firing temperatures are from about 450 ° C to 650 ° C. From the above firing conditions, an amorphous solid solution phase is formed.

The catalyst thus formed effectively promotes the dehydrogenation of ethylbenzene for styrene monomer conversion. That is, the conversion rate of ethylbenzene and the selectivity of styrene become high.

The production method of the styrene monomer may be a known method for producing a styrene monomer, but is preferably prepared by adding the above catalyst with ethylbenzene to promote the dehydrogenation reaction of ethylbenzene in the presence of CO ₂ . By carrying out such dehydrogenation in the presence of CO ₂ , the styrene monomer can be produced in an energy-saving form, and a useful effect of increasing the life of the catalyst can be obtained.

Accordingly, the dehydrogenation reaction for styrene monomer conversion is about 400 ° C. to 700 ° C. at atmospheric pressure, 0 to 5 mL / h flow rate of ethylbenzene, and 10 to 50 mL / flow rate of CO ₂ . preferably at h. This is because the conversion rate and styrene selectivity of ethylbenzene are high under the above reaction conditions. Here, the appropriate reaction temperature is about 400 ℃ to 700 ℃, but may be carried out at a higher or lower temperature. The reaction pressure may also be carried out at atmospheric pressure, or at higher or lower pressures. However, since it is desirable to operate at pressures as low as practicable, atmospheric or lower pressures are preferred. Such a process is preferably carried out in a series of processes, preferably using a fixed bed reactor consisting of a single step in one or several reactors.

The ethyl benzene and with, the product and a weak acid agent to the dilution of the reaction the addition of CO ₂ to the hydrocarbon reactant coking carbon residue, such as a predetermined amount in the catalyst can help to be removed by the CO _2.

Here, the contact time (W / F) of the reactant-containing gas and the catalyst is expressed as the weight of the catalyst relative to the sum of the flow rates of the reactant, the carrier gas (nitrogen) and the CO ₂ gas.

The catalyst according to the present invention formed as described above may have many uses. In particular, not only the dehydrogenation reaction according to the present invention but also various reactions such as dehydration, hydrogenation sulfidation, hydrogenation denitrification, desulfurization, hydrogenation desulfurization, dehydrogenation halogenation, reforming, steam reforming, decomposition, hydrocracking, hydrogenation To catalyze isomerization, disproportionation, oxychlorination, dehydrogenation of hydrocarbons or other organic compounds, oxidation and / or reduction reactions, Klaus reactions, treatment of exhaust gases from internal combustion engines, demetallization, methanation or migration conversion May be suitable.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it is a matter of course that the scope of the present invention is not limited or limited to only the following examples.

<Example 1>

In this example, a binary TiO ₂ -ZrO ₂ composite metal oxide catalyst having this functionality of acid-base was prepared. TiO ₂ -ZrO ₂ catalysts were prepared using the same moles of salt, respectively. A homogeneous aqueous solution of zirconium nitrate was prepared at room temperature. A suitable amount of titanium chloride salt, which is decomposed in acid and cooled in an ice bath before its addition, is added to the homogeneous aqueous solution of zirconium nitrate. The mixed salt solution was precipitated using an aqueous ammonia solution at regular intervals, subjected to static hydrothermal treatment at 100 ° C. for 24 hours, and then calcined at 650 ° C. under atmospheric pressure for 6 hours using a muffle furnace. . The surface area of the 50% TiO ₂ -ZrO ₂ catalyst was 129 m 2 / g. This is at least 8 times greater than the surface area of pure TiO ₂ prepared under the same conditions, and at least 5 times greater than pure ZrO ₂ .

About 1.0 g of the calcined catalyst was loaded into a stainless steel micro reactor equipped with quartz wool. The reaction was carried out under specific reaction conditions. Nitrogen gas was used to obtain the reaction temperature, and pretreated for about 0.5 to 1.0 hour at the reaction temperature. The reaction was then injected into the reactor with CO ₂ . The flow of nitrogen was stopped before CO ₂ was flowed.

Table 1 shows the catalytic activity of pure ZrO ₂ , TiO ₂ and 50% TiO ₂ -ZrO ₂ composite oxide catalysts.

catalyst TiO ₂ ZrO ₂ TiO ₂ -ZrO ₂ Time of Stream (TOS) Time EB (concentration,%) SM (selectivity,%) EB (concentration,%) SM (selectivity,%) EB (concentration,%) SM (selectivity,%) One 27.6 98.9 27.5 98.9 39.7 88.7 2 34.2 98.8 25.9 98.8 42.7 86.9 3 28.8 98.6 26.9 98.9 52.2 98.5 4 27.5 98.9 21.8 98.2 52.1 98.9 5 25.0 98.8 21.0 99.5 51.2 98.8 6 25.0 99.2 18.8 98.4 50.7 98.2 7 24.8 98.8 17.8 98.3 50.3 98.8 8 22.7 98.2 17.2 98.3 48.6 98.8 9 20.8 99.0 16.8 98.2 47.7 98.7 10 20.0 98.5 16.1 98.1 47.6 98.7

EB = ethylbenzene, SM = styrene monomer

Reaction conditions: temperature = 600 ° C, pressure = 1 atmosphere, CO ₂ / EB = 5.1 (molar ratio), contact time (W / F) = 16.73 g _catalyst h / mole

<Example 2>

A 25% MnO ₂ -ZrO ₂ binary composite metal oxide catalyst was prepared. MnO ₂ -ZrO ₂ composite oxide catalysts were prepared by coprecipitation. Here, zirconium nitrate and manganese nitrate were used as precursors, and an aqueous ammonia solution was used as a hydrogenating agent. Each precursor 0.1 M complex aqueous solution was stirred at room temperature. After obtaining a homogeneous solution, an appropriate amount of aqueous ammonia solution was added to bring the pH of the solution to 9. It was hydrothermally treated at 100 ° C. for 24 hours. The resulting precipitate was filtered under reduced pressure, washed thoroughly with water, dried in an oven at 120 ° C. for 12 hours, and finally calcined at 550 ° C. in muffle for 6 hours. The catalytic activity of the 25% MnO ₂ -ZrO ₂ binary composite metal oxide catalyst was examined using CO ₂ as described above. The advantages of using CO ₂ in the dehydrogenation of ethylbenzene are shown in this example.

activation Use CO ₂ Use N ₂ TOS time EB (%,%) SM (selectivity,%) EB (concentration,%) SM (selectivity,%) One 30.21 98.68 33.72 95.46 2 45.38 98.29 53.33 99.04 3 53.82 98.85 53.41 98.71 4 51.06 99.12 46.50 99.18 5 48.61 98.79 44.28 99.14 6 46.88 98.96 45.67 99.17 7 44.21 99.38 38.94 98.92 8 43.29 98.81 37.94 98.21 9 40.80 98.08 37.33 98.93 10 39.25 97.88 36.53 98.80

EB = ethylbenzene, SM = styrene monomer

Reaction conditions: temperature = 550 ° C., pressure = 1 atmosphere, CO ₂ or N ₂ / EB = 5.1 (molar ratio), contact time (W / F) = 16.73 g _catalyst h / mole

<Example 3>

In order to confirm the effects of the K ₂ O promoter and CO ₂ , a 60% TiO ₂ -ZrO ₂ catalyst and a 3% K ₂ O-60% TiO ₂ -ZrO ₂ catalyst were prepared and their catalytic activity was observed. Preparation of 60% TiO ₂ -ZrO ₂ is similar to Example 1. 3% by weight of K ₂ O was deposited on the surface of the calcined 60% TiO ₂ -ZrO ₂ composite oxide catalyst by an incipient wetness method with aqueous potassium carbonate solution. After evaporation to dryness, it was calcined for 6 hours at 600 ℃. The obtained activity data is shown in Table 3.

catalyst TiO ₂ -ZrO ₂ K ₂ O-TiO ₂ -ZrO ₂ TOS time EB (concentration,%) SM (selectivity,%) EB (concentration,%) SM (selectivity,%) One 63.68 94.86 59.74 98.32 2 72.71 94.53 62.89 98.46 3 73.13 95.82 65.22 99.28 4 66.90 96.01 65.19 99.32 5 62.59 97.22 65.03 99.38 6 63.92 96.60 64.71 99.44 7 61.12 96.05 64.39 99.41 8 58.80 96.94 64.11 99.32 9 55.32 95.46 63.86 99.61 10 53.09 95.63 63.28 99.27

EB = ethylbenzene, SM = styrene monomer

Reaction conditions: temperature = 600 ° C, pressure = 1 atmosphere, CO ₂ or K ₂ O / EB = 5.1 (molar ratio), contact time (W / F) = 16.73 g _catalyst h / mole

<Example 4>

In this example, K ₂ O—MnO ₂ —TiO ₂ —ZrO ₂ catalysts were prepared, and the excellent catalytic activity of the oxidative dehydrogenation of ethylbenzene for styrene conversion in the presence of CO ₂ was observed. The K ₂ O—MnO ₂ —TiO ₂ —ZrO ₂ catalyst comprising MnO ₂ (10 mol%), TiO ₂ (40 mol%), ZiO ₂ (50 mol%), and 4 wt% K ₂ O was added to the ternary system. Deposited on the composite oxide surface. An aqueous homogeneous composite solution of precursor nitrates of manganese and zirconium was obtained by mechanical stirring at room temperature. Anhydrous titanium chloride was decomposed to nitric acid under ice-cooled conditions before addition to the complex solution of manganese and zirconium. The decomposed titanium chloride was added rapidly under constant mechanical stirring conditions, and then subjected to hydrolysis and static hydrothermal reaction at its boiling point temperature. The composite hydroxide precipitate was isolated by filtration under reduced pressure and washed thoroughly with deionized water to completely remove chloride and nitrate ions. The resulting composite hydroxide precipitate was dried at 120 ° C. for 12 hours. Finally, the dried composite hydroxide was calcined at 650 ° C. for 6 hours.

Dehydrogenation of ethylbenzene for styrene conversion in the presence of CO ₂ was carried out at 600 ° C. for 10 hours as described in the previous examples. Under the reaction conditions, the flow rate of ethylbenzene was 3 ml / h and the flow rate of CO ₂ was 30 ml / h under atmospheric pressure. The results are summarized in Table 4.

TOS time EB (concentration,%) SM (Yield,%) SM (selectivity,%) One 73.21 71.82 98.10 2 76.21 73.71 96.98 3 78.77 77.38 98.24 4 80.64 79.13 98.13 5 78.57 77.96 99.22 6 73.63 72.38 98.30 7 69.36 67.95 97.97 8 67.68 65.77 97.18 9 65.44 64.21 98.12 10 64.70 62.43 96.49

EB = ethylbenzene, SM = styrene monomer

Reaction conditions: temperature = 600 ° C, pressure = 1 atmosphere, CO ₂ or N ₂ / EB = 5.1 (molar ratio), contact time (W / F) = 16.73 g _catalyst h / mole

As described above, according to the present invention, the life of the catalyst is increased, the use of steam can be eliminated in the dehydrogenation reaction of ethylbenzene, and the use of CO ₂ in the reaction is environmentally friendly and economically harmless to the process. By this, a styrene monomer can be obtained with high yield and high selectivity.

Claims (14)

A composite oxide catalyst containing zirconium oxide and titanium oxide, the composite oxide catalyst for dehydrogenation of ethylbenzene for styrene conversion, further comprising any one or more selected from potassium carbonate or potassium oxide. delete delete delete delete delete The method of claim 1, wherein the zirconium oxide is 10 to 90 mol%, any one or more mixtures selected from potassium carbonate or potassium oxide is 1 to 10 mol%, and ethyl for styrene conversion, characterized in that the balance of titanium oxide. Composite oxide catalyst for dehydrogenation of benzene. Dissolving the zirconium salt and the titanium salt in deionized water, and further adding at least one selected from potassium carbonate or potassium oxide to form a solution, and then forming a complex metal hydroxide precipitate; And Filtering the metal hydroxide precipitate to dryness under reduced pressure, and then calcining the same. Method for producing a composite oxide catalyst for dehydrogenation of ethylbenzene for styrene conversion comprising a. delete delete The method for preparing a complex oxide catalyst for dehydrogenation of ethylbenzene for styrene conversion according to claim 8, wherein the pH concentration of the solution is in the range of 7 to 12. The method of claim 8, wherein the calcining temperature is in the range of 450 ° C. to 650 ° C. for the dehydrogenation catalyst of ethylbenzene for styrene conversion. 13. Dehydrogenation of the ethylbenzene by mixing the catalyst of claim 1 or 7 or the catalyst prepared according to claim 8 with ethylbenzene in the presence of CO ₂ . Method for producing a styrene monomer comprising a. The method of claim 13, wherein the dehydrogenation reaction is performed under atmospheric pressure, the reaction temperature is 400 ℃ to 700 ℃, the flow rate of ethylbenzene is 0 to 5 ml / h, and the flow rate of CO ₂ is 10 to 50 ml / h styrene Method for producing a monomer.