KR102258044B1 - A method for synthesizING PVP-added catalyst for production of ethylene oxide and its application - Google Patents

Abstract

The present invention relates to a method for producing a catalyst capable of producing ethylene oxide in high yield from ethylene by adjusting the size of metal crystals by adding polyvinylpyrrolidone in the preparation of a catalyst for producing ethylene oxide. The method for preparing the catalyst includes: (A) forming a solution by dissolving a compound containing at least one first metal selected from the group consisting of Ag, Pd, and Pt in a solvent; (B) After dissolving at least one compound containing a second metal selected from the group consisting of cesium, rhenium, molybdenum, lithium, sodium, potassium, and tungsten in a solvent, it is mixed with the solution obtained in step (A). Mixing to form a catalyst precursor solution; (C) adding polyvinylpyrrolidone (PVP) to the catalyst precursor solution in an amount of 0.3 to 0.6% by weight relative to the catalyst precursor solution; And (D) impregnating the carrier.

Description

{A method for synthesizING PVP-added catalyst for production of ethylene oxide and its application}

The present invention relates to a method for producing a catalyst for producing ethylene oxide. In particular, the present invention relates to a method for producing a catalyst capable of producing ethylene oxide in high yield from ethylene by adjusting the size of metal crystals by adding polyvinylpyrrolidone in the preparation of a catalyst for producing ethylene oxide.

Ethylene oxide is a three-membered cyclic ether, the simplest epoxide, and the simplest epoxide of C ₂ H ₄ 0. Ethylene oxide has a property that is well soluble in both water and organic solvents, and is usefully used as an intermediate in the synthesis of organic compounds.

For example, ethylene glycol can be obtained by reacting ethylene oxide with water using an acid as a catalyst. If the amount of water is reduced by this reaction, polyethylene glycol can also be produced. In addition, when an acid is reacted in the absence of water, polyethylene oxide is produced by cationic polymerization. In addition, by reacting with the Grignard reagent (RMgX), a primary alcohol may be obtained after hydrolysis. It is known to exhibit high reactivity as a hydroxy ethylating agent against various nucleating agents in order to release the distortion energy according to the ring opening of the three-membered ring. Ethylene oxide having such a wide industrial use is produced according to various synthesis methods, but as a typical production method, synthesis by direct gas-phase oxidation of ethylene is mentioned. The direct gaseous oxidation of ethylene is a reaction of C ₂ H ₄ +1/2O ₂ →C ₂ H ₄ O, and various catalysts have been proposed for this reaction.

For example, Korean Patent No. 10-1606875 discloses a method for preparing a catalyst containing alpha-alumina with a small surface area suitable as an Ag support, which is used in a reaction for obtaining ethylene oxide from ethylene, but silver nano The catalytic effect according to the size of the particles is not recognized.

Conventionally, the use of an Ag metal as a catalyst for synthesizing ethylene oxide from ethylene and α-Al ₂ O ₃ as a carrier is well known and widely used. This is advantageous in selectively generating ethylene oxide in the ethylene oxidation reaction, but it is necessary to efficiently use Ag in that it uses Ag, which is a noble metal. In order to efficiently use Ag, it is important to keep the size of Ag particles small when supported on a _{carrier (α-Al 2} O _{3 ), but a technology related to this has not yet been developed.}

Korean Patent Registration No. 10-1606875

Accordingly, an object of the present invention is to provide a high-efficiency catalyst synthesis method that increases both the ethylene conversion rate and the ethylene oxide production rate by highly dispersing metal particles for efficient use of metal in the catalyst used in the production of ethylene oxide.

The present invention in order to solve the above problems,

(A) forming a solution by dissolving a compound containing at least one first metal selected from the group consisting of Ag, Pd, and Pt in a solvent;

(B) After dissolving at least one compound containing a second metal selected from the group consisting of cesium, rhenium, molybdenum, lithium, sodium, potassium, and tungsten in a solvent, it is mixed with the solution obtained in step (A). Mixing to form a catalyst precursor solution;

(C) adding polyvinylpyrrolidone (PVP) to the catalyst precursor solution in an amount of 0.3 to 0.6% by weight relative to the catalyst precursor solution; And

(D) It provides a method for producing a catalyst for producing ethylene oxide, comprising the step of impregnating a carrier.

In addition, in the present invention, in the production of ethylene oxide by gas phase reaction from molecular oxygen or a mixed gas containing oxygen in the presence of a catalyst for producing ethylene oxide prepared by the above production method, the reaction temperature is 200 to 250°C. , Gas Hourly Space Velocity (GHSV, h ^-1 )) is 3000 to 5000, it provides a method for producing ethylene oxide.

According to the production method of the catalyst for ethylene oxide production of the present invention, the metal crystal size can be controlled by introducing PVP into the catalyst system, so that the metal can be efficiently used in the production of the catalyst, and the ethylene conversion rate and ethylene oxide in the synthesis of ethylene oxide. It is possible to provide an efficient catalyst with both increased production rates.

1 is an XRD graph showing a crystal peak of silver (Ag) according to the amount of polyvinylpyrrolidone (PVP) added.
2 is a SEM image of the catalyst according to the amount of PVP added.

The present invention comprises the steps of (A) dissolving a compound containing at least one first metal selected from the group consisting of Ag, Pd and Pt in a solvent to form a solution; (B) After dissolving at least one compound containing a second metal selected from the group consisting of cesium, rhenium, molybdenum, lithium, sodium, potassium, and tungsten in a solvent, respectively, the solution obtained in step (A) and Mixing to form a catalyst precursor solution; (C) adding polyvinylpyrrolidone (PVP) to the catalyst precursor solution in an amount of 0.3 to 0.6% by weight relative to the catalyst precursor solution; And (D) provides a method for producing a catalyst for producing ethylene oxide comprising the step of impregnating a carrier.

In the method for preparing a catalyst according to the present invention, a metal is dissolved in a solvent to form a catalyst precursor solution, polyvinylpyrrolidone is added to the catalyst precursor solution, a carrier is impregnated therein, dried under reduced pressure, and then calcined under air flow. Includes that.

In the present invention, it was confirmed that the addition of polyvinylpyrrolidone can affect the size control of the metal particles supported on the carrier, and by optimizing the amount of PVP added, a catalyst capable of producing ethylene oxide in high yield from ethylene is provided. do.

PVP is a type of surfactant and forms a microshell at a specific concentration. The size of the microshells changes according to the PVP concentration, and the size of the Ag particles is affected by the size of the microcells formed at this time. Polyvinylpyrrolidone used in the present invention has a molecular weight of 20000 to 55000.

In one embodiment, the polyvinylpyrrolidone has a molecular weight of about 50000. The polyvinylpyrrolidone may be used in an amount greater than 0.25% by weight and less than 0.7% by weight based on the catalyst precursor solution. When the amount of PVP added is less than 0.25% by weight, the size of the metal particles is larger than that of the case where PVP was not added, and the ethylene conversion rate and the synthesis rate of ethylene oxide were slow, and when the amount of PVP added exceeded 0.7% by weight, It is difficult to achieve uniform catalyst synthesis because PVP is not completely dissolved. In another embodiment, the polyvinylpyrrolidone is used in an amount of 0.3 to 0.6% by weight based on the catalyst precursor solution. In a further embodiment, the polyvinylpyrrolidone is used in an amount of 0.4 to 0.5% by weight based on the catalyst precursor solution.

In one embodiment according to the present invention, the crystal size of the metal obtained by the addition of polyvinylpyrrolidone in the above range may have a range of 16 nm to 23 nm (confirmed through XRD analysis). In another embodiment, the crystal size of the metal obtained upon addition of polyvinylpyrrolidone has a range of 16 nm to 18 nm.

In one embodiment according to the present invention, the metal supported on the carrier is Ag.

The carrier may be silica, α-alumina, θ-alumina, or the like. In one embodiment, the carrier is α-alumina.

In one embodiment according to the present invention, the catalyst is Ag/α-Al ₂ O ₃ .

1 is an XRD graph showing a crystal peak of silver (Ag) according to the amount of polyvinylpyrrolidone (PVP) added.

The results shown in FIG. 1 are _{for a catalyst in which α-Al 2} O ₃ was used as a carrier and an Ag metal was supported.At this time, the crystal size of Ag was determined using the Scherrer equation based on the (022) crystal peak of the XRD graph. Was calculated.

In the present invention, the solvent of the catalyst precursor solution may be distilled water, an ethylenediamine solution, and an organic solvent. In one embodiment, the solvent is distilled water.

In one embodiment according to the present invention, the method includes forming a metal-ethylene diamine complex by introducing ethylene diamine in the step of mixing the precursors of each metal component.

The catalyst of the present invention may include one or more metals selected from the group consisting of cesium, rhenium, molybdenum, lithium, sodium, potassium, and tungsten.

According to an embodiment of the present invention, the catalyst is 15 to 25 wt% of silver (Ag), 300 to 800 ppm of rhenium (Re), 100 to 400 ppm of molybdenum (Mo), 500 to 1500 ppm of cesium (Cs), and 1 It may contain to 100 ppm of lithium (Li).

In one embodiment according to the present invention, the specific surface area of the carrier is 0.25 to 10 m ² /g. In another embodiment, the specific surface area of the carrier is 0.25 to 1 m ² /g.

In addition, the present invention provides a method for producing ethylene oxide by gas-phase reaction from ethylene in molecular oxygen or a mixed gas containing oxygen in the presence of a catalyst for producing ethylene oxide prepared by the above production method.

As a form of the gas phase reaction, for example, a continuous type, a batch type, a semi-batch type, or the like can be adopted. The amount of the catalyst used in the present invention can be appropriately set depending on the amount of ethylene or the like supplied.

When preparing the ethylene oxide, the gas phase reaction temperature may be 200 to 250 °C, and the gas hourly space velocity (GHSV, h ^-1 ) may be 3000 to 5000. In addition, the pressure may be 10 to 17 atmospheres. In one embodiment, the pressure may be 14 to 16 atmospheres. When the reaction pressure is low, the selectivity of ethylene oxide is low, and when the reaction pressure is high, the risk of explosion increases.

According to one embodiment, the reaction gas used in the production of the ethylene oxide contains 15 to 30% of ethylene. In another embodiment, the reaction gas comprises 15 to 30% ethylene. In one embodiment, the reaction gas contains 0.1 to 5 ppm of chlorohydrocarbon, such as 0.5 to 2 ppm.

Examples of the chlorohydrocarbon include CHCl ₃ , CH ₂ Cl ₂ , CHCl ₃ , CH ₃ Cl, and the like.

Hereinafter, the action and effect of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example of the invention, and the scope of the invention is not limited to any meaning by this.

Example

[Example 1]

Add 7 g of silver oxalate powder to distilled water (7 ml), and stir while cooling to 5°C. To this, 3.5 ml of an aqueous ethylene diamine solution (92 wt% of ethylene diamine and 8 wt% of H ₂ O) was added and stirred to form a solution. Re ₂ O ₇ 18.7 mg and (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O 11 mg, respectively, are dissolved in a mixture of ethylene diamine and aqueous ammonia (ethylene diamine, 30% aqueous ammonia solution, and distilled water are mixed in the same mass ratio), and LiNO ₃ 14 mg and _{24.1 mg of Cs 2} CO ₃ are each dissolved in 1 ml of distilled water, added to the solution, and stirred to form a catalyst precursor solution. Thereafter, 100 mg (corresponding to 0.5% by weight of the catalyst precursor solution) of polyvinylpyrrolidone (MW about 50000) is added to the catalyst precursor solution and stirred for 2 hours or more. After absorbing the catalyst precursor solution into 15 g of dried α-Al ₂ O _{3, it is dried under reduced pressure.} After drying under reduced pressure and firing at 250° C. for 5 to 15 minutes under a flow of air, (Cs,Re,Li,Mo)Ag/α-Al ₂ O ₃ catalyst was obtained.

The (Cs,Re,Li,Mo)Ag/α-Al ₂ O ₃ catalyst obtained above is 20 wt% silver (Ag), 712 ppm rhenium (Re), 300 ppm molybdenum (Mo), 985 ppm cesium (Cs). ), and 70 ppm of lithium (Li).

[Comparative Example 1]

A catalyst was prepared in the same manner as in Example 1, except that the PVP content was set to 0% by weight.

[Comparative Example 2]

A catalyst was prepared in the same manner as in Example 1, except that the PVP content was 0.1% by weight.

[Comparative Example 3]

A catalyst was prepared in the same manner as in Example 1, except that the PVP content was 0.25% by weight.

[Experimental Example 1]

The ethylene oxide synthesis reaction was carried out using a fixed bed catalytic reactor. After filling the catalyst prepared in Example 1 and Comparative Examples 1 to 3 in a 1/2 inch reactor, ethylene ^{was supplied at GHSV 3500 h -1} and 15% to 25% of ethylene, 7 to 8% of oxygen, and EDC (ethylene dichloride) was brought into contact with a mixed gas containing 1 to 5 ppm under a pressure of 14 to 15 atmospheres at a reaction temperature of 200 to 250°C to proceed with an ethylene oxide synthesis reaction.

When synthesizing ethylene oxide prepared using the catalyst prepared in Example 1 and Comparative Examples 1 to 3, the ethylene oxide (EO) selectivity according to the amount of PVP added, the ethylene (EL) conversion rate, the EO generation rate, and the Ag crystal size were determined. The calculated results are shown in Table 1 below.

As shown in FIG. 1, as shown in FIG. 1, the Scherrer equation was calculated based on the (022) crystal peak of the XRD graph from the result of XRD analysis of the catalyst according to the amount of PVP added during the preparation of the _{Ag/α-Al 2} O _{3 catalyst.} It was calculated using.

PVP addition amount (wt%) EO selectivity (%) EL conversion rate (mmol/g _-Ag h) EO generation rate
(mmol/g _-Ag h) Ag crystal size (022) PVP (0.5) (Example 1) 0.5 86.2 39.87 34.37 16.7 nm PVP(0) (Comparative Example 1) - 85.1 32.17 27.37 18.3 nm PVP(0.1) (Comparative Example 2) 0.1 86.6 26.87 23.27 22.4 nm PVP (0.25) (Comparative Example 3) 0.25 86.3 29.06 25.08 18.7 nm

From the results of Table 1, the catalyst prepared by adding 0.5wt% PVP (Example 1) reduced the Ag crystal size compared to the catalyst prepared without adding PVP (Comparative Example 1). It can be seen that it can be formed and supported on a carrier. In addition, as a result of using the catalyst of Example 1 for the ethylene oxide synthesis reaction, the ethylene oxide selectivity increased from 85.1% to 86.2% compared to the catalyst prepared without the addition of PVP, and both the ethylene conversion rate and the ethylene oxide production rate were increased. As it appears to be, it is confirmed that it is an efficient catalyst.

Claims (11)

(A) forming a solution by dissolving a compound containing at least one first metal selected from the group consisting of Ag, Pd, and Pt in a solvent;
(B) After dissolving at least one compound containing a second metal selected from the group consisting of cesium, rhenium, molybdenum, lithium, sodium, potassium, and tungsten in a solvent, respectively, the solution obtained in step (A) and Mixing to form a catalyst precursor solution;
(C) adding polyvinylpyrrolidone (PVP) having a molecular weight of 20,000 to 55,000 to the catalyst precursor solution in an amount of 0.3 to 0.6% by weight relative to the catalyst precursor solution; And
(D) impregnating the carrier,
The solvent used in steps (A) and (B) is distilled water,
In the step (A) and step (B), ethylene diamine is added when forming a solution of each of the metal-containing compounds, a method for producing a catalyst for producing ethylene oxide. The method of claim 1, wherein the first metal is Ag. The method of claim 2, wherein the Ag has a crystal size of 16 nm to 18 nm. The method of claim 1, wherein the carrier is α-alumina. delete The method of claim 1, wherein the carrier has a specific surface area of 0.25 to 1 m ² /g. The method of claim 1, wherein the addition amount of the polyvinylpyrrolidone is 0.4 to 0.5% by weight. The method of claim 1, wherein the catalyst is 15 to 25 wt% of silver (Ag), 300 to 800 ppm of rhenium (Re), 100 to 400 ppm of molybdenum (Mo), 500 to 1500 ppm of cesium (Cs), and 1 to 100 ppm The method for producing a catalyst for producing ethylene oxide containing lithium (Li). Oxidation of ethylene from molecular oxygen or a mixed gas containing oxygen in the presence of a catalyst for producing ethylene oxide prepared by the method according to any one of claims 1 to 4 and 6 to 8 by a gas phase reaction In producing ethylene, the reaction temperature is 200 to 250 °C, the gas space velocity (Gas Hourly Space Velocity (GHSV, h ^-1 )) is 3000 to 5000, the method for producing ethylene oxide. The method for producing ethylene oxide according to claim 9, wherein a reaction gas containing 15 to 30% ethylene is used. The method of claim 10, wherein the reaction gas contains 0.1 to 5 ppm of chlorohydrocarbon.

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