KR20090043852A - Method of preparing titanium silicalite-1 catalyst in the presence of polystyrene particle and method of preparing propylene oxide using said catalyst - Google Patents

Abstract

The present invention relates to a method for preparing a titanium silicalite-1 (TS-1) catalyst, which is a titanium-containing zeolite having an MFI structure, and a method for producing propylene oxide (PO) using the catalyst. More specifically, a method for preparing a titanium silicalite-1 catalyst by hydrothermal synthesis in the presence of polystyrene (PS) particles, and propylene is epoxidized using hydrogen peroxide as an oxidant in the presence of the catalyst. The present invention relates to a method for producing propylene oxide.

Since titanium silicalite-1 prepared according to the present invention has less anatase phase inactive to propylene epoxidation reaction, when titanium silicalite-1 according to the present invention is used as a catalyst for propylene epoxidation reaction, It has the effect of obtaining better selectivity and yield of propylene oxide.

Titanium Silica Light-1, Polystyrene, Propylene, Hydrogen Peroxide, Propylene Oxide, Propylene Epoxide

Description

Method of preparing titanium silicalite-1 catalyst in the presence of polystyrene particles and method of preparing propylene oxide using said catalyst}

The present invention relates to a process for preparing a catalyst for the reaction of producing propylene oxide (PO) from propylene. More specifically, Titanium Silicalite-1 (TS-1), a titanium-containing zeolite, is synthesized to have higher activity, and the propylene epoxidation reaction using hydrogen peroxide as an oxidizing agent. It is related with the method of using as a catalyst.

Currently, propylene oxide is manufactured by the chlorohydrin process and the indirect oxidation process using peroxide as an oxidant. However, these processes use oxidizing agents that are harmful to the environment and generate a large amount of by-products. There is a cost problem. As a result, attention has been focused on environmentally friendly alternative processes, and researches on propylene epoxidation reaction using hydrogen peroxide as an oxidizing agent have been conducted.

Catalyst for propylene epoxidation reaction using hydrogen peroxide as oxidant, [π-C ₅ H ₅ NC ₁₆ H ₃₃ ] ₃ [PW ₄ O ₁₆ ], [γ-SiW ₁₀ O ₃₄ (H ₂ O) ₂ ] ^4- Heteropolyacid catalysts such as [Z. Xi, N. Zhou, Y. Sun, K. Li, Science, Vol. 292, 11 (2001) / N. Zhou, Z. Xi, G. Cao, S. Gao, Appl. Catal. A, vol. 250, p. 239 (2003) / K. Kamata, K. Yonehara, Y. Sumida, K. Yamaguchi, S. Hikichi, N. Mizuno, Science, Vol. 300, pp. 964 (2003) / N. Mizuno, K. Yamaguchi, K. Kamata, Coord. Chem. Rev., Vol. 249, p. 1944 (2005)], as well as microporous molecular sieve catalysts containing titanium such as titanium silicalite-1 and Ti-MCM-22 [MG Clerici, G. Bellussi, U. Romano, J. Catal., Vol. 129, p. 159 (1991) / G. Li, X. Wang, H. Yan, Y. Chen, Q. Su, Appl. Catal. A, vol. 218, p. 31 (2001) / X. Liu, X. Wang, X. Guo, G. Li, Catal. Today, pp. 93-95, p. 505 (2004) / G. Li, Z. Wang, H. Yan, Y. Liu, X. Liu, Appl. Catal. A, vol. 236, p. 1 (2002) / HJ Ban, KY Lee, JK Lee, ST Chung, WS Ahn, Korean Chem. Eng. Res., Vol. 44, 121 (2006)]. Particularly, among the microporous molecular sieve catalysts containing titanium, Ti-MCM-22 has been reported to exhibit propylene oxide selectivity of 100% in the propylene epoxidation reaction [HJ Ban, KY Lee, JK Lee, ST Chung, WS Ahn, Korean Chem. Eng. Res., Vol. 44, 121 (2006)].

However, since Ti-MCM-22 is too complex to synthesize, it is difficult to apply it to commercialization with known synthesis methods, and much research has not been carried out, and titanium silicalite-1 (Titanium Silicalite-) is relatively simple. 1: Research on propylene epoxidation reaction using TS-1) catalyst has been very active [MG Clerici, G. Bellussi, U. Romano, J. Catal., Vol. 129, 159 (1991) / G.F. Thiele, E. Roland, J. Mol. Catal. A, vol. 117, p. 351 (1997) / G. Li, X. Wang, H. Yan, Y. Chen, Q. Su, Appl. Catal. A, vol. 218, p. 31 (2001) / X. Liu, X. Wang, X. Guo, G. Li, Catal. Today, pp. 93-95, p. 505 (2004) / G. Li, Z. Wang, H. Yan, Y. Liu, X. Liu, Appl. Catal. A, vol. 236, p. 1 (2002) / C. Wang, B. Wang, X. Meng, Z. Mi, Catal. Today, Vol. 74, 15 (2002) / V. Arca, A. Boscolo Boscoletto, N. Fracasso, L. Meda, G. Ranghino, J. Mol. Catal. A, vol. 243, p. 264 (2006)].

Furthermore, further studies have been conducted on catalysts for the propylene epoxidation reaction using oxygen gas directly without using an oxidizing agent such as hydrogen peroxide. Pd (OAc) ₂ -[(C ₆ H ₁₃ ) ₄ N] ₃ heteropolyacid catalyst such as [PO ₄ [W (O) (O ₂ ) ₂ ] ₄ ] [Y. Liu, K. Murata, M. Inaba, N. Mimura, Appl. Catal. B, vol. 58, p. 51 (2005)], medium pore molecular sieve catalysts containing titanium such as Ti-Al-HMS, Au / Ti-MCM-41, Au / Ti-MCM-48 [Y. Liu, K. Murata, M. Inaba, N. Mimura, Catal. Lett., Vol. 89, p. 49 (2003) / BS Uphade, Y. Yamada, T. Akita, T. Nakamura, M. Haruta, Appl. Catal. A, Vol. 215, p. 137 (2001) / BS Uphade, T. Akita, T. Nakamura, M. Haruta, J. Catal., Vol. 209, p. 331 (2002)], such as gold, platinum, palladium, and silver Titanium-containing microporous molecular sieve catalyst supporting precious metals [B. Taylor, J. Lauterbach, WN Delgass, Appl. Catal. A, vol. 291, p. 188 (2005) / N. Yap, RP Andress, WN Delgass, J. Catal., Vol. 226, p. 156 (2004) / L. Cumaranatunge, WN Delgass, J. Catal., Vol. 232, P. 38 (2005) / G. Jenzer, T. Mallat, M. Maciejewski, F. Eigenmann, A. Baiger, Appl. Catal. A, vol. 208, p. 125 (2005) / X. Guo, R. Wang, X. Wang, J. Hao, Catal. Today, 93-95, pp. 211 (2004) / R. Wang, X. Guo, X. Wang, J. Hao, Catal. Today, 93-95, pp. 217 (2004).

The direct oxidation of propylene using oxygen gas has many advantages both environmentally and economically because it does not use an oxidizing agent, but shows very low propylene oxide yield. Therefore, titanium silicalite-1 having excellent activity even under mild reaction conditions is used. Much attention has been focused on the research and commercialization of propylene epoxidation reactions using catalysts and hydrogen peroxide as oxidants.

Titanium Silicalite-1 (TS-1) is a zeolite with an MFI structure, such as ZSM-5, with a zig-zag channel with a pore size of 5.1 × 5.5 A and 5.3 × 5.6 A. The linear channels have a three-dimensional pore structure where they intersect with each other, and each pore consists of 10 atomic rings [EM Flanigen, JM Bennett, RW Grose, JP Cohen, RL Patton, RM Kirchner, JV Smith, Nature , Vol. 271, 512 (1978)]. In addition, titanium silicalite-1 is composed of [TiO ₄ ]-[SiO ₄ ] units, and up to 2.5% of the silicon in the structure can be substituted with titanium. An anatase phase is formed by this. Titanium silicalite-1 crystals are cubic and have a size of about 200 nm.

Titanium silicalite-1 is a catalyst capable of performing liquid phase oxidation of various organic substances under mild reaction conditions using hydrogen peroxide as an oxidizing agent. Hydroxylation of phenol, Amoximation of cyclohexanone and present Many studies have been made as catalysts for the epoxidation reaction of olefins to be achieved in the invention. In titanium silicalite-1, titanium may exist in tetrahedral structure, octahedral structure and anatase phase. The active point of the propylene epoxidation reaction targeted in the present invention is only tetrahedral titanium surrounded by silica units filled in the MFI structure. It is known that titanium on octahedral structure and anatase is inactive [B. Notari, Catal. Today, Vol. 18, p. 163 (1993) / F.Z. Zhang, X.W. Guo, X.S. Wang, G. Li, J. C. Zhou, J.Q. Yu, C. Li, Catal. Lett., Vol. 72, p. 235 (2001) / S. Bordiga, A. Damin, F. Bonino, C. Lamberti, Top Organomet. Chem., 16, 37 (2005)].

On the other hand, even when a small amount of sodium is added to titanium silicalite-1 in the above reactions, the activity tends to drop sharply, which is a general phenomenon occurring in a liquid phase reaction using a titanium-containing molecular sieve as a catalyst and hydrogen peroxide as an oxidizing agent. to be. Therefore, it is necessary to remove sodium when the sodium precursor is not used or used when preparing the catalyst. When titanium silicalite-1 is used as a catalyst for the propylene epoxidation reaction using methanol as a solvent and hydrogen peroxide as an oxidant, 1,2-propanediol and 1-meth as a by-product together with propylene oxide are used. 1-Methoxy-2-Propanol and 2-Methoxy-1-Propanol are mainly formed. It is reported that the silanol group at the defect site of the titanium silicalite-1 catalyst acts as an acidic point to form a byproduct from propylene oxide, which can be neutralized with an aqueous solution of salt [G.F. Thiele, E. Roland, J. Mol. Catal. A, vol. 117, p. 351 (1997)]. In addition, since titanium silicalite-1 does not contain aluminum, it has hydrophobicity compared to aluminum-containing zeolites such as ZSM-5, and thus exhibits good adsorption of organic molecules in a water atmosphere, and thus hydrophilicity compared to methanol and water. This weak hydrogen peroxide and propylene will adsorb well. Thus, the hydrophobicity of the tetrahedral titanium species in titanium silicalite-1 has been reported to play an important role in the activity of the propylene epoxidation reaction [L.Y. Chen, G.K. Chuah, S. Jaenicke, J. Mol. Catal. A, vol. 132, p. 281 (1998)].

As described above, the titanium silicalite-1 catalyst shows excellent activity in the propylene epoxidation reaction using hydrogen peroxide as an oxidizing agent even under mild reaction conditions, and the synthesis process is relatively simple. Therefore, many studies on commercialization process have been conducted. 'S techniques have technical limitations in enhancing the activity of the catalyst because of the difficulty of eliminating the formation of anatase.

The technical problem to be achieved in the present invention is to provide a method for synthesizing titanium silicalite-1 having a higher activity in the propylene epoxidation reaction.

According to an aspect of the present invention, there is provided a method for preparing a titanium silicalite-1 catalyst comprising: (a) mixing a silicon precursor, a titanium precursor, and a structural alignment agent in a nitrogen atmosphere; (b) adding and mixing polystyrene particles to the mixture of step (a); (c) heating the mixture of step (b) in which the polystyrene particles are mixed to evaporate an alcohol component; (d) adding distilled water to the mixture of step (c) in which the alcohol component is evaporated and hydrothermally synthesizing; And (e) drying the solid component formed through step (d) and calcining to obtain a titanium silicalite-1 catalyst.

Another aspect of the present invention relates to a titanium silicalite-1 catalyst prepared by the above method.

Another aspect of the present invention relates to a method for preparing propylene oxide by epoxidizing propylene using hydrogen peroxide as an oxidant in the presence of a titanium silicalite-1 catalyst prepared by the above method.

Since titanium silicalite-1 prepared according to the present invention has less anatase phase inactive to propylene epoxidation reaction, when titanium silicalite-1 according to the present invention is used as a catalyst for epoxidation of propylene, It has the effect of obtaining better selectivity and yield of propylene oxide.

In addition, since the production method according to the present invention using polystyrene particles when synthesizing the titanium silicalite-1 catalyst is very simple and easy to secure reproducibility, there is no additional problem caused by the use of polystyrene particles even when applied to the commercialization process. There is no advantage.

Hereinafter, the present invention will be described in more detail.

Titanium silicalite-1 according to the present invention is a molecular sieve having a unique structure composed of titanium and silicon, and is prepared using a silicon precursor, a titanium precursor, a structural alignment agent, polystyrene particles, and distilled water. That is, the method for producing a titanium silicalite-1 catalyst according to the present invention comprises the steps of: (a) mixing a silicon precursor, a titanium precursor and a structural alignment agent in a nitrogen atmosphere; (b) adding and mixing polystyrene particles to the mixture of step (a); (c) heating the mixture of step (b) in which the polystyrene particles are mixed to evaporate an alcohol component; (d) adding distilled water to the mixture of step (c) in which the alcohol component is evaporated and hydrothermally synthesizing; And (e) drying the solid component formed through step (d) and calcining to obtain a titanium silicalite-1 catalyst.

In the method for preparing the titanium eukarylite-1 catalyst according to the present invention, examples of the silicon precursor used as a starting material include colloids of silica including tetraalkylorthosilicate such as tetraethylorthosilicate. Solutions, or silicates of alkali metals such as sodium silicate and potassium silicate.

However, as described above, titanium silicalite-1 has a sharp decrease in activity in the propylene epoxidation reaction even when a small amount of sodium is added, so that silicates of alkali metals such as sodium silicate are difficult to be used as silicon precursors. Therefore, in the present invention, it is preferable to use tetraalkyl orthosilicate, such as tetraethyl orthosilicate, as the silicon precursor.

In addition, the titanium precursor may be a titanium alkoxide-based compound such as titanium ethoxide, titanium isopropoxide, titanium butoxide, or titanium tetrachloride. It is preferable to use.

For the synthesis of titanium silicalite-1 according to the present invention, the silicon precursor, the titanium precursor, the structural alignment agent, and the polystyrene should form a transparent gel before hydrothermal synthesis. In general, the transparent gel is faster because the hydration rate of titania is faster than that of silica. In order to form well, it is necessary to slow down the hydration rate of titania to be similar to the hydration rate of silica.In the case of titanium alkoxide used as a titanium precursor, when the alkyl group of the alkoxide is larger and longer, the hydration rate is slower. Most preferably, titanium butoxide is used as the titanium precursor.

Tetrapropylammonium Hydroxide is preferred as a structural alignment agent for the synthesis of titanium silicalite-1, and tetrapropylammonium Bromide may be used together with a basic solution such as ammonia water.

In the method for preparing titanium silicalite-1 according to the present invention, before the hydrothermal synthesis, the silicon precursor, the titanium precursor, the structural alignment agent, the polystyrene particles, and the distilled water are mixed, and an appropriate ratio thereof is as follows.

The molar ratio of silicon precursor to titanium precursor used in the present invention is preferably 10 to 120: 1, but when the molar ratio of silicon precursor to titanium precursor is less than 10, there is a problem in that an excess of anatase phase is formed. If the molar ratio of silicon precursor to is greater than 120, there is a problem that too few active points are formed due to the low titanium content. The molar ratio of the most preferable silicon precursor: titanium precursor is 50-60: 1.

The molar ratio of the structural alignment agent: silicon precursor to be used in the present invention is preferably 0.1 to 1: 1, but when the molar ratio of the structural alignment agent to the silicon precursor is less than 0.1, the desired structural alignment effect cannot be achieved. On the contrary, if it is larger than 1, there is a problem that crystal formation is not rational due to the use of an excessive amount of structural alignment agent. More preferably, the molar ratio of the structural alignment agent: silicon precursor is 0.45: 1.

According to the present invention, in order to increase the activity of the titanium silica light-1 catalyst, polystyrene particles are mixed with the starting material when preparing the titanium silica light-1, and the polystyrene used in the method according to the present invention is a styrene monomer. (Styrene) and divinylbenzene, a crosslinking agent, are mixed and then a polymerization initiator, potassium persulfate, is added to copolymerize styrene and divinylbenzene. Round particles are formed in an intertwined state. The size of the individual particles of polystyrene formed by copolymerization of styrene and divinylbenzene is preferably 200 to 800 nm. If smaller than 200 nm, there is a possibility of affecting the formation of titanium silicalite-1 structure, and if larger than 800 nm There is a problem that the surface area is small and does not have an effective effect.

The polystyrene particles are added to the mixture of the silicon precursor, the titanium precursor, and the structural alignment agent, stirred at a high speed so that the hydrophobic polystyrene particles can be dispersed well, and then heated to 50-70 ° C. to evaporate the alcohol component contained therein. Let's do it. By evaporating the alcohol component as much as possible it is possible to further improve the efficiency of the subsequent hydrothermal synthesis process.

After evaporating the alcohol component, a predetermined ratio of distilled water is added and hydrothermal synthesis is performed. In this case, the molar ratio of distilled water: silicon precursor is preferably 10 to 200: 1, more preferably 35: 1. . If the molar ratio of distilled water to silicon precursor is less than 10, there may be a problem in that it does not form an appropriate pressure during hydrothermal synthesis, on the contrary, if it is larger than 200, the mixture of the structural alignment agent, the silicon precursor and the titanium precursor is excessively diluted. There is a problem.

The preferred temperature for hydrothermal synthesis is 130 ~ 200 ℃, more preferably it is preferable to proceed with hydrothermal synthesis at 175 ℃, it is preferable to use a high temperature and high pressure reactor in order to maintain such hydrothermal synthesis conditions.

Titanium silicalite-1 catalyst according to the present invention by recovering the solid crystals formed through hydrothermal synthesis, washed with distilled water, etc., dried at 100-110 ° C. for 12 hours, and calcined at 500-600 ° C. for 6 hours. Can be prepared. Since the polystyrene particles present in the mixture during hydrothermal synthesis are all removed through the calcination process of the prepared catalyst, the finally produced titanium silicalite-1 catalyst does not have polystyrene particles and components of polystyrene.

The titanium silicalite-1 catalyst prepared according to the present invention has a suitable physical properties and activity to obtain high selectivity and yield when used as a catalyst for the propylene epoxidation reaction, the titanium silicalite-1 catalyst according to the present invention. The propylene epoxidation reaction using is a liquid phase reaction using hydrogen peroxide as an oxidizing agent.

Propylene epoxidation reaction according to the present invention is carried out in a high-temperature high-pressure reactor (Autoclave), it is preferable to maintain a constant reaction temperature through a heating device surrounding the reactor outer wall and a thermometer installed inside the reactor.

The total reaction pressure is determined solely by the pressure of the reactant propylene, which is measured through a manometer connected to the reactor. It is preferable to keep reaction temperature at 30-60 degreeC, Preferably it is 40 degreeC, and it is good to advance reaction, maintaining reaction pressure at 4-10 atm, More preferably, 7 atm.

It is preferable that the stirring speed in the reactor is 500 to 1000 rpm, more preferably 700 to 800 rpm, and methanol, ethanol, propanol, acetonitrile, etc. may be used as a solvent for the propylene epoxidation reaction. Most preferably used as.

The concentration of hydrogen peroxide used as the oxidant is preferably 2.5 to 7.5 wt% based on the mass of methanol used as the solvent, more preferably 2.5 wt%.

The amount of titanium silicalite-1, which is a catalyst used in the method for producing propylene oxide according to the present invention, was fixed such that the molar ratio of titanium / hydrogen peroxide was 5.1 × 10 −4 to 1.2 × 10 −3, preferably 8.2 × 10 −4. .

Hereinafter, a production example of a titanium silicalite-1 catalyst using no polystyrene particles, a production example of polystyrene particles, a production example of a titanium silicalite-1 catalyst in the presence of polystyrene particles, and a titanium silicalite synthesized without using polystyrene particles- 1 and experimental examples of the titanium silicalite-1 catalyst synthesized in the presence of polystyrene particles, and a catalyst for the propylene epoxidation reaction using hydrogen peroxide as an oxidizing agent will be described in more detail through examples and comparative examples using the catalysts. The following Preparation Examples and Examples are intended to illustrate the present invention and are not intended to limit the scope of the present invention.

In the following examples, the propylene epoxidation reaction activity was measured at 30 minute intervals, and the reaction time for comparing the activity of each catalyst was set to 1 hour 30 minutes.

compare Production Example  1 to 6: Preparation of Titanium Silica Light-1 Catalyst Without Polystyrene Particles

For the synthesis of titanium silicalite-1 (TS-1), a silicon precursor, a titanium precursor, a structural alignment agent, and distilled water were mixed in an appropriate ratio before hydrothermal synthesis.

Tetraethylorthosilicate was used as the silicon precursor, titanium butoxide was used as the titanium precursor, and tetrapropylammonium hydroxide was used as the structural alignment agent for forming the MFI structure of titanium silicalite-1. In particular, in order to prevent the silicon precursor and the titanium precursor from being hydrated by moisture present in the air, the mixture was mixed in a nitrogen atmosphere.

More specifically, 20 ml of tetraethylorthosilicate and an appropriate amount of titanium butoxide were mixed so that the molar ratio of silicon: titanium precursor was 10-120: 1, and 20 mol of titanium silicalite-1 was added to the solution. 44 ml of wt% tetrapropylammonium hydroxide were dropped dropwise. It was observed that as the tetrapropylammonium hydroxide was added the solution gradually became opaque and soon became clear again.

In order to speed up the hydration and remove the alcohol component, the mixture of dilute gel formed through the above process was heated at 65 ° C. for about 2 hours. Put it. The resulting mixture of silicon precursor, titanium precursor, structural alignment agent and distilled water was hydrothermally synthesized at 175 ° C. for 96 hours using a high temperature and high pressure reactor. As a result, it was confirmed that white titanium silicalite-1 crystals were formed. It was. Titanium silicalite-1 crystals were washed with distilled water, dried at 105 ° C. for 12 hours, and then calcined at 550 ° C. for 6 hours to prepare titanium silicalite-1 that can be used as a catalyst for propylene epoxidation reaction. Thus, through the elemental component analysis (ICP-AES) of the catalyst prepared by varying the silicon: titanium molar ratio, it was confirmed that each catalyst was synthesized in the desired silicon: titanium mole ratio within the error range of the analysis. Is shown in Table 1.

Elemental Composition Ratio of Titanium Silicalite-1 Prepared According to Comparative Preparation Example catalyst Ti content (wt%) Molar ratio of Si / Ti Comparative Production Example 1 6.96 10.1 Comparative Production Example 2 2.44 31.4 Comparative Production Example 3 1.51 51.3 Comparative Production Example 4 1.36 57.1 Comparative Production Example 5 1.18 66.1 Comparative Production Example 6 0.67 117.2

Production Example  One

Preparation of Polystyrene Particles

Polystyrene particles used in the production process of the titanium silicalite-1 catalyst was prepared by the copolymerization reaction of styrene monomer and divinylbenzene as described above, the specific production process is as follows.

Since the oxygen contained in the distilled water may interfere with the formation of uniform particles before proceeding with the polymerization reaction, nitrogen was sufficiently flowed at a rate of 50 ml / min for at least 1 hour to remove the oxygen in the distilled water. In addition, 3M caustic soda was added to the styrene monomer to remove the stabilizer present in the styrene monomer, followed by stirring for 2 hours or more. After completing the pretreatment, 25 ml of styrene monomer was added to 350 ml of distilled water and stirred at 70 ° C. for 1 hour to disperse. Then, 10 ml of divinylbenzene, a crosslinking agent, was added and stirred for 1 hour. The mixed solution of styrene monomer and divinylbenzene is turbid, but when 0.11 g of potassium persulfate (Potassuim Persulfate), a polymerization initiator is added, the polymerization starts and the mixture of styrene and divinylbenzene gradually becomes milky. It was. In this state, the mixture was stirred at 70 ° C. for 24 hours, and the milky solution of the polymerization reaction was dried in air to prepare polystyrene particles. The resulting polystyrene particles were in the form of several dozens of dozen round particles entangled with each other.

Preparation of Titanium Silicalite-1 Catalyst in the Presence of Polystyrene Particles

The molar ratio of silicon precursor: structural alignment agent: distilled water was fixed at 1: 0.45: 35 as in Comparative Preparation Example 1, and the molar ratio of silicon: titanium precursor was adjusted to 50 to 60: 1. Tetraethylorthosilicate was used as the silicon precursor, titanium butoxide was used as the titanium precursor, and tetrapropylammonium hydroxide was used as the structural alignment agent.

Synthesis process of titanium silicalite-1 was also the same as in Comparative Preparation Example 1, but the process of adding the polystyrene particles prepared as described above to the mixture of the silicon precursor, the titanium precursor and the structural alignment agent was added. More specifically, 20 ml of tetraethylorthosilicate was mixed with an appropriate amount of titanium butoxide in a nitrogen atmosphere so that the molar ratio of silicon to titanium precursor was about 50 to 60: 1, and 20 wt% of tetrapropyl was added to the solution. 44 ml of ammonium hydroxide was added dropwise. Polystyrene particles were added to the solution formed through the above process, and the mixture was stirred at a high speed so that hydrophobic polystyrene particles could be dispersed well. The mixture of dilute gel in which polystyrene particles were dispersed was heated at 65 ° C. for 2 hours, and distilled water was added so that the molar ratio of distilled water: silicon precursor was 35: 1 when the alcohol component was removed. The mixed solution thus formed was hydrothermally synthesized at 175 ° C. for 96 hours using a high temperature and high pressure reactor, and as a result, it was confirmed that white titanium silicalite-1 crystals were formed. Titanium silicalite-1 crystals were washed with distilled water, dried at 105 ° C. for 12 hours, and then calcined at 550 ° C. for 6 hours to prepare titanium silicalite-1 from which polystyrene particles were removed. Elemental component analysis (ICP-AES) of the prepared catalyst confirmed that the catalyst was synthesized at a desired ratio within the analytical error range. The titanium content in the prepared catalyst was 1.36 wt%, and the silicon / titanium ratio was It was found to be 57.5.

Experimental Example  1: UV absorption analysis results of titanium silicalite-1 synthesized without using polystyrene particles and titanium silicalite-1 synthesized in the presence of polystyrene particles

1 shows titanium silicalite-1 synthesized without using polystyrene particles according to Comparative Preparation Example (shown as Comparative Preparation Example 4 in FIG. 1) and titanium silicalite-1 synthesized in the presence of polystyrene particles according to Preparation Example 1 The ultraviolet absorption analysis result of (shown as manufacture example 1 in FIG. 1) is shown.

Here, titanium silicalite-1 synthesized without using polystyrene particles was analyzed by selecting Comparative Preparation Example 4 having a similar titanium content to the catalyst prepared by Preparation Example 1 among various catalysts prepared in Comparative Preparation Example.

As described above, in general, titanium in titanium silicalite-1 may exist in a tetrahedral structure, an octahedral structure, and an anatase phase. Each of these phases may be identified through ultraviolet absorption analysis. In the case of titanium present in the MFI structure, an absorption band is formed around 220 nm in a tetrahedral structure, an absorption band appears in the vicinity of 270 nm in an octahedral structure, and an absorption band appears in the vicinity of 340 nm when present in the anatase phase. In the background of the ultraviolet absorption analysis of FIG. 1, the titanium silicalite-1 synthesized without the use of polystyrene particles and the titanium silicalite-1 synthesized in the presence of the polystyrene particles were formed with an absorption band near 220 nm. Absorption bands did not appear around 270 nm, it was confirmed that all titanium present in the MFI structure is a tetrahedral structure.

In addition, absorption bands formed near 340 nm were hardly observed in titanium silicalite-1 synthesized in the presence of polystyrene particles, but significantly larger in titanium silicalite-1 synthesized without using polystyrene particles. When the excess titanium precursor is used, the anatase phase is formed by the remaining titanium filled in the structure, but the two titanium silicalite-1s subjected to ultraviolet absorption analysis have very similar titanium contents with silicon / titanium ratios of 57.1 and 57.5. Therefore, the difference in absorption band formation formed near 340 nm could not be considered simply due to the titanium content, and it was confirmed that the synthesis of titanium silicalite-1 in the presence of polystyrene particles can reduce the formation of the anatase phase.

Experimental Example  2: Nitrogen adsorption-desorption analysis results of titanium silicalite-1 synthesized without using polystyrene particles and titanium silicalite-1 synthesized in the presence of polystyrene particles

As a result of measuring the surface area through nitrogen adsorption-desorption analysis, the BET surface area of titanium silicalite-1 synthesized without using polystyrene particles was about 457 m ² / g and titanium silicalite-1 synthesized in the presence of polystyrene particles. The BET surface area of was 444 m ² / g. The two BET surface areas can be judged to be very similar values considering the analytical error, and therefore, the use of polystyrene in the synthesis of titanium silicalite-1 does not cause a change in the catalyst surface area. This means that the difference in activity between titanium silicalite-1 synthesized without polystyrene and titanium silicalite-1 synthesized in the presence of polystyrene does not arise from the surface area difference of the catalyst.

compare Example  1: Propylene of Titanium Silica Light-1 Catalyst Synthesized without Using Polystyrene Particles Epoxidation  reaction

Propylene epoxidation reaction experiments were carried out using titanium silicalite-1 prepared by Comparative Preparation Example as a catalyst, and a graph of propylene oxide yield according to the change of silicon / titanium (Si / Ti) content of titanium silicalite-1 is shown. Same as FIG. The propylene epoxidation reaction was carried out using methanol as a solvent and hydrogen peroxide as an oxidizing agent, and the reaction pressure was controlled only by the pressure of propylene as a reactant. In a 210 ml high-temperature reactor, 0.5 g of titanium silicalite-1 catalyst with 80 ml of methanol and 5.2 ml of 30 wt% hydrogen peroxide was added thereto, stirred at 700 rpm, and heated to 40 ° C. When the temperature was adjusted to 40 ℃ propylene was added so that the pressure inside the reactor to 7 atm, the reaction mixture was analyzed at 30 minute intervals. As the reaction proceeded, hydrogen peroxide was not additionally supplied, so the conversion rate of hydrogen peroxide increased as the reaction time passed, and it was confirmed that there was almost no increase in the conversion rate after 1 hour and 30 minutes. Therefore, the activity comparison of the titanium silicalite-1 catalyst was performed using the reaction result at 1 hour 30 minutes. Hydrogen peroxide conversion was calculated by measuring the change in hydrogen peroxide concentration using iodine titration. The selectivity of propylene oxide was determined from the results of analysis of propylene oxide and by-products using gas chromatography. The conversion of hydrogen peroxide, the selectivity of propylene oxide, and the yield of propylene oxide in the propylene epoxidation reaction using titanium silicalite-1 as a catalyst were calculated using the following equations.

Yield of propylene oxide (%) = hydrogen peroxide conversion × propylene oxide selectivity × 100

According to the graph of the change in the yield of propylene oxide according to the content of silicon / titanium (Si / Ti) of FIG. The yield of propylene oxide was 84.2% with a conversion rate and 86.3% propylene oxide selectivity, and the catalyst of Comparative Preparation Example 4 with a silicon / titanium ratio of 57.1 was similarly similar to the hydrogen peroxide conversion rate of 97.5% and propylene oxide selectivity of 86.5%. Yield of propylene oxide was shown in%. The two catalysts showed very similar activity for the propylene epoxidation reaction due to the small difference in silicon / titanium, and showed higher activity than other catalysts. Therefore, the titanium silicalite-1 catalyst having a silicon / titanium ratio of 50 to 60 was found to have the highest activity.

Example  1: Propylene of Titanium Silicalite-1 Catalyst Synthesized in the Presence of Polystyrene Particles Epoxidation  reaction

As a result of confirming the silicon / titanium ratio of the catalyst showing high activity among the titanium silicalite-1 catalysts prepared by the Comparative Preparation Example, as shown in Comparative Example 1, the Comparative Preparation Example having a silicon / titanium ratio of 50 to 60 The catalyst of 4 showed high activity in the propylene epoxidation reaction with a yield of propylene oxide of 84.4%. Therefore, as shown in Preparation Example 1, by adjusting the amount of the titanium precursor so that the mole ratio of silicon / titanium is between 50 and 60 to synthesize titanium silicalite-1 in the presence of polystyrene, and used as a catalyst for propylene epoxidation reaction It was.

As shown in Example 1, the propylene epoxidation reaction was carried out at 40 ° C. and 7 atm using methanol as a solvent and hydrogen peroxide as an oxidizing agent. In a 210 ml high-temperature reactor, 80 ml of methanol, 5.2 ml of 30 wt% hydrogen peroxide and 0.5 g of titanium silicalite-1 catalyst were added, and then the temperature and pressure were adjusted to the reaction conditions. The reaction mixture was analyzed at intervals. As a result of looking at the reaction result at 1 hour and 30 minutes after the progress of the reaction, the hydrogen peroxide conversion rate was 97.8% and the propylene oxide selectivity was 94.9%, thereby obtaining a high propylene oxide yield of 92.8%.

Experimental Example  3: Propylene of Titanium Silica-1 Catalyst Synthesized without Polystyrene Particles and Titanium Silica-1 Catalyst Synthesized in the Presence of Polystyrene Particles Epoxidation  Reaction activity comparison

In the Comparative Preparation Example, titanium silicalite-1 was synthesized without using polystyrene particles and then used as a catalyst for the propylene epoxidation reaction according to Comparative Example 1, and the titanium silicalite-1 having a silicon / titanium ratio of 57.1 (compared to Preparation Example 4) showed the highest activity. In general, titanium silicalite-1 having a silicon / titanium ratio of 50 to 60 was found to exhibit high activity in the propylene epoxidation reaction. Therefore, in Example 1, the silicon / titanium ratio was adjusted to 50 to 60 to synthesize titanium silicalite-1, and polystyrene particles were synthesized by adding a silicon precursor, a titanium precursor, a structural alignment agent, and a mixed solution of distilled water. As a result, a titanium silicalite-1 (preparation example 1) catalyst having a silicon / titanium ratio of 57.5 was obtained. As such, the titanium silicalite-1 synthesized without using polystyrene particles and the titanium silicalite-1 synthesized in the presence of polystyrene particles have very similar titanium contents. The effects of the polystyrene particles present in the synthesis were examined.

3 shows the results of the propylene epoxidation reaction with titanium silicalite-1 synthesized without using polystyrene particles and titanium silicalite-1 synthesized in the presence of polystyrene particles. As described above, since hydrogen peroxide used in a batch reactor and used as an oxidizing agent is not injected in the middle of the reaction, the hydrogen peroxide conversion rate increases with time, and hydrogen peroxide is almost consumed after 1 hour and 30 minutes so that there is no change in the conversion rate. I could confirm that. As shown in Table 2, titanium silicalite-1 synthesized without using polystyrene particles (catalyst represented by Comparative Preparation Example 4 in FIGS. 2 and 3) and titanium silicalite-1 synthesized in the presence of polystyrene particles (FIG. In Example 3, the conversion rate of hydrogen peroxide at 1 hour 30 minutes after the start of the reaction was very similar to 97.5% and 97.8%, respectively. On the other hand, the selectivity of propylene oxide was 86.5% for the titanium silicalite-1 catalyst synthesized without using the polystyrene particles, but the titanium silicalite-1 synthesized in the presence of the polystyrene particles was 94.9%. As a result of using the catalyst prepared, high propylene oxide selectivity was obtained.

Comparison of Propylene Epoxidation Activity of Titanium Silica Light-1 Synthesized without Polystyrene Particles and Titanium Silica Light-1 Synthesized in the Presence of Polystyrene Particles catalyst Hydrogen peroxide conversion rate (%) Propylene Oxide Selectivity (%) Propylene Oxide Yield (%) Comparative Production Example 4 97.5 86.5 84.4 Preparation Example 1 97.8 94.9 92.8

This difference in propylene epoxidation reaction activity can be correlated with the results of ultraviolet absorption analysis described in Experimental Example 1. According to Experiment 1, although the titanium content is similar, titanium silicalite-1 synthesized without using polystyrene particles forms an absorption band due to anatase phase larger than titanium silicalite-1 synthesized in the presence of polystyrene particles. It was confirmed that the synthesis of titanium silicalite-1 in the presence of polystyrene particles can reduce the formation of the anatase phase. Since titanium on the anatase is inactive in the propylene epoxidation reaction, titanium silicalite-1 synthesized in the presence of polystyrene particles shows higher activity in the propylene epoxidation reaction.

1 is an ultraviolet absorption spectrum of titanium silica light-1 (Comparative Example 4) synthesized without using polystyrene particles and titanium silica light-1 (Preparation Example 1) synthesized in the presence of polystyrene particles.

FIG. 2 is a graph showing a change in yield of propylene oxide according to silicon / titanium (Si / Ti) content of titanium silica light-1 (Comparative Examples 1 to 6) synthesized without using polystyrene particles.

3 shows the epoxidation activity of propylene over time of titanium silicalite-1 (Comparative Example 4) synthesized without using polystyrene particles and titanium silicalite-1 (Preparation Example 1) synthesized in the presence of polystyrene particles. This is a graph.

Claims (9)

(a) mixing a silicon precursor, a titanium precursor and a structural alignment agent in a nitrogen atmosphere; (b) adding and mixing polystyrene particles to the mixture of step (a); (c) heating the mixture of step (b) in which the polystyrene particles are mixed to evaporate an alcohol component; (d) adding distilled water to the mixture of step (c) in which the alcohol component is evaporated and hydrothermally synthesizing; And (e) a method of preparing a titanium silicalite-1 catalyst comprising drying the solid component formed through the step (d) and calcining to obtain a titanium silicalite-1 catalyst. The method of claim 1, wherein the molar ratio of the silicon precursor: structural alignment agent: distilled water is 1: 0.1 to 1: 10 to 200. The method of claim 1, wherein the molar ratio of silicon / titanium contained in the silicon precursor and the titanium precursor is 50 to 60. The method of claim 1, wherein the polystyrene particles are 250 to 500 nm in size. The method of claim 1, wherein the polystyrene particles are prepared by a copolymerization reaction of styrene as a monomer and divinylbenzene as a crosslinking agent. The method of claim 1, wherein the silicon precursor is tetraalkylorthosilica, the titanium precursor is titanium butoxide, and the structural alignment agent is tetrapropylammonium hydroxide. Way. Titanium silicalite-1 catalyst prepared by the method according to any one of claims 1 to 6. A process for producing propylene oxide, comprising the step of epoxidation by reacting propylene with hydrogen peroxide, which is an oxidizing agent, in the presence of the titanium silicalite-1 catalyst according to claim 7. The process for producing propylene oxide according to claim 8, wherein methylene is used as a solvent for the epoxidation reaction.

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