KR100281470B1 - Method for preparing hydrophobic catalyst with even pore distribution for hydrogen isotope exchange in gas phase, vapor phase and liquid phase - Google Patents

Abstract

The present invention relates to a method for preparing a hydrophobic catalyst having even pore distribution, and specifically, a polymer having a uniform pore distribution by controlling a monomer / solvent ratio, a crosslinking degree, and a swelling agent / precipitant ratio. The hydrophobic catalyst of the present invention prepared by preparing a carrier and then carrying a catalyst evenly distributes pores formed in the polymer carrier to uniformly disperse the metal such as platinum group, which is a catalyst supported on the pores, thereby improving the efficiency of the catalyst. In addition to increasing the reaction rate in the gas phase-vapor phase-liquid phase it can be particularly useful as a catalyst for hydrogen isotope exchange reaction.

Description

Method for preparing hydrophobic catalyst with even pore distribution for hydrogen isotope exchange in gas phase, vapor phase and liquid phase

The present invention relates to a method for preparing a hydrophobic catalyst having even pore distribution, and specifically, a polymer having a uniform pore distribution by controlling a monomer / solvent ratio, a crosslinking degree, and a swelling agent / precipitant ratio. The present invention relates to a method for preparing a hydrophobic catalyst capable of increasing the reaction rate of a hydrogen isotope exchange reaction in a gaseous-vapor-liquid phase by preparing a carrier and then supporting the catalyst.

A catalyst for hydrogen isotope exchange was first developed by H. C. Urey and A. V. Gross and presented in US Pat. No. 2,690,379 in 1954. They described a method for preparing heavy water by exchanging a platinum group element on an inert carrier such as activated carbon to exchange heavy hydrogen-containing hydrogen with water, and the disadvantage of this patent is that the catalyst is hydrogen and hydrogen isotope during the steam period. It catalyzes the exchange, but the activity is greatly reduced when the catalysts come in contact with liquid water.

It is a hydrophobic catalyst proposed to solve the problem of the performance fall of such a catalyst. In 1975, Steven Steven (WH Stevens) proposed the first hydrophobic catalyst in U.S. Patent No. 3,888,974. He prepared a hydrophobic catalyst by coating an organic hydrophobic resin film such as fluorinated olefin resin and silicone resin on a platinum supported catalyst. The tritium exchange reaction was carried out in the vapor-vapor phase-liquid phase. In addition, J. H. Rolston et al. Developed a catalyst supporting platinum group metals on hydrophobic carriers such as porous PTFE (polytetrafluoroethylene), polyethylene, and polystyrene in US Patent No. 4,025,560 in 1977. The characteristics of this catalyst solved the problem of producing an incomplete coating portion and coating film uniformity by coating the carrier itself with a hydrophobic material. However, the carrier materials used were high molecular organic materials and hydrophobic carbon, and most of the organic carriers used had very low surface area or very small particle size, and thus, it was difficult to be used in actual hydrogen isotope exchange process.

JP Butler et al. Developed a hydrophobic catalyst assembly including a hydrophilic layer in 1980 US Patent No. 4,126,667, focusing on the reaction rate determining mechanism of the hydrogen isotope exchange process in the reaction between water vapor and water in the hydrophilic layer. It was. The development of such a catalyst enabled the hydrogen isotope exchange reaction in the trickle bed.However, in the case of the trickle bed, the channeling phenomenon of the liquid flow in the catalyst bed must be prevented. There is a problem that the actual operation is difficult, such as to prevent the flooding phenomenon in the.

On the other hand, M. Shimizu et al., Paying attention to the fact that styrene-based polymers have hydrophobicity, and prepared spherical hydrophobic carriers using styrene-divinylbenzene in Japanese Patent No. 59-27618. By adjusting the carrier can be prepared in the desired size. In this case, the size of the particles could be controlled, but the pore characteristics inside the catalyst carrier, which had a significant effect on the actual isotope exchange reaction, could not be changed.

The hydrophobicity of the catalyst is essential for the reaction in the gas phase-vapor phase-liquid phase, and the pore distribution of the catalyst must be formed evenly. If the catalyst pores are too fine, water is easily condensed in the pores, making it difficult to diffuse gas into the catalyst, and the reaction proceeds very slowly. On the contrary, when only the large pores exist, the surface area of the entire pores decreases, such as the platinum group contained in the pores. Dispersion of the metal worsens and the efficiency of the catalyst is greatly reduced.

Accordingly, the present inventors have continued to study the pore distribution of the hydrophobic catalyst while adjusting the pore distribution in the polymer carrier by controlling the monomer / solution ratio, the degree of crosslinking, and the ratio of the swelling agent / precipitant in the solvent. The present invention was completed by finding out that even hydrophobic catalyst can be prepared.

It is an object of the present invention to provide a method for preparing a hydrophobic catalyst having even pore distribution.

1 is a graph showing the pore distribution of the polymer carrier prepared in Examples and Comparative Examples of the present invention,

- -Example -: Comparative Example

2 is a graph comparing the reaction rate constants of hydrogen isotope exchange reactions using the hydrophobic catalysts prepared in Examples and Comparative Examples.

- -Example -: Comparative Example

In order to achieve the above object, in the present invention, a polymer carrier having a desired pore distribution and a specific surface area is prepared by controlling the ratio of monomer / solvent, crosslinking degree and swelling agent / precipitant, and then carrying a catalyst to hydrophobic even pore distribution. It provides a method for providing a polymer catalyst.

Hereinafter, the present invention will be described in detail.

As described above, in the present invention, a polymer carrier having an even pore distribution is prepared by adjusting a monomer / solvent ratio, a degree of crosslinking and a swelling agent / precipitant, and then a catalyst is supported to prepare a hydrophobic polymer catalyst having an even pore distribution. The hydrophobic polymer catalyst thus prepared may be particularly useful as a catalyst for hydrogen isotope exchange in gas phase-vapor phase-liquid phase.

Isotope exchange between hydrogen and liquid water on a hydrophobic catalyst can be represented by Scheme 1 below.

Reaction Scheme 1 is considered to consist of two stages of continuous reactions such as Scheme 2 and Scheme 3.

Scheme 2 corresponds to the deuterium exchange reaction between hydrogen and water vapor at the catalytic metal active point, and Scheme 3 corresponds to the deuterium transfer from water and steam to water with evaporation and condensation at the gas-liquid interface. .

A suitable catalyst for the exchange reactions in water, steam and gas phase is wet-proofed. When liquid water condenses into the pores, it becomes difficult to saturate the pores, which makes it difficult to diffuse into the catalyst, which is one of the reactants. Therefore, the catalyst must have hydrophobicity, and when the catalyst has hydrophobicity, the water molecules in the liquid phase do not condense in the pores. The reaction between vapor phase and gas phase occurs at the active point inside. Another characteristic of catalysts suitable for exchange reactions in water, steam and gas phase is the even distribution of catalyst pores. If the pores in the catalyst are very small, the vapor phase water molecules, the other one of the reactants, are difficult to diffuse into the pores of the catalyst, and the vaporized water molecules once condensed in the pores. If the pores inside the catalyst are very large, the surface area in the catalyst is reduced, reducing the active point at which the reaction can occur or worsening the dispersion of metal for the active point. Therefore, the pores inside the catalyst should have an even distribution.

First, in the present invention, the hydrophobic polymer catalyst may include all polymers having a general hydrophobic polymer as a carrier. Preferably, the hydrophobic polymer catalyst is a styrene hydrophobic polymer catalyst in which a platinum group metal is supported by using a styrene polymer as a carrier. .

In the present invention, in order to control the pores of the polymer catalyst carrier, i) controlling the ratio of the solvent and the monomer during bulk polymerization, ii) controlling the degree of crosslinking, and iii) controlling the ratio of the swelling agent and the precipitating agent forming the solvent. Adjust That is, in the present invention, the above three conditions may be combined to prepare a polymer having a pore having a desired shape and a high specific surface area.

As the ratio of monomer to solvent increases, a gel product or a bulk product with few pores is obtained, and vice versa. In order to have a macroporous form and even pore distribution, the monomer / solvent ratio is preferably about 0.3 to 1.0.

Crosslinking degree, for example, in the case of styrene polymer, represents the degree of styrene chains connected to each other with divinylbenzene, etc. As the degree of crosslinking increases, the physical strength of the polymer carrier increases, thereby stabilizing the pore-shaped structure. The degree of crosslinking in order to maintain a stable pore shape and have an even pore distribution is preferably at least 30% or more depending on the ratio of monomer / solvent.

In the polymer polymerization, the more swelling agent in the solvent, the smaller pore and high specific surface area of the polymer product is obtained. The more precipitant, the macroporous form and relatively low specific surface area of the product are obtained. In order to maintain a suitable specific surface area in which the function as a catalyst is maintained and to have an even pore distribution, it is preferable that the ratio of the swelling agent / precipitant is 0.5 or less.

Meanwhile, the type of swelling agent and precipitant constituting the solvent used to control the pore distribution of the polymer catalyst also plays an important role. There are various kinds of swelling agents and precipitants used in the polymer polymerization reaction, and in the present invention, aromatic compounds including benzene, toluene, etc. are mainly used as swelling agents, and saturated hydrocarbons and alcohols are mainly used as precipitants. Since these solvents have different densities and solubility in styrene monomers, the physical properties of the products are also different when different solvents are used. For example, even if the solvent belonging to the same precipitating agent and the swelling agent is significantly different in density from the styrene monomer, when the monomo and the solvent are mixed and reacted, the nonuniformity caused by the difference in density between the solvent and the styrene monomer appears to some degree. It is difficult to obtain a carrier. In addition, it is difficult to obtain a uniform catalyst carrier in one reactor because the difference in solubility also varies depending on the degree of uniformity.

The production method of the present invention is mainly applied to a method for preparing a platinum group catalyst which is a hydrophobic catalyst using a styrene-divinylbenzene copolymer as a polymer carrier, and is effective for enhancing the activity of hydrogen isotope exchange reaction, in addition to other hydrophobic catalysts. It can be applied to improve the activity of the reaction involving this catalyst by applying the pore distribution of the polymer carrier evenly applied to the manufacturing method of.

In the present invention, a hydrophobic catalyst is prepared by controlling the ratio of monomer / solvent, crosslinking degree and swelling agent / precipitant, and performing a hydrogen isotope exchange reaction using the prepared catalyst. It was confirmed that the more even the catalyst, the higher the reaction rate constant.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are merely to illustrate the present invention is not limited by the following examples.

EXAMPLE

20 g of styrene monomer

30 g of divinylbenzene monomers

Dichlorobenzene (swelling agent) 30 g

Amyl alcohol (precipitator) 70 g

Benzoyl peroxide (initiator) 0.5 g

Into the reactor, a solution containing 20 g of styrene monomer, 30 g of divinylbenzene monomer, 30 g of dichlorobenzene as a swelling agent, and 70 g of amyl alcohol as a precipitant was injected with a solution of 0.5 g of benzoyl peroxide as a polymerization initiator. It was reacted for a time to prepare a polymer carrier having a crosslinking degree of 33%. The ratio of the swelling agent / precipitant in this case was 3/7.

Platinum was supported on the prepared polymer carrier to prepare a hydrophobic styrene polymer catalyst suitable for hydrogen isotope exchange reaction.

[Comparative Example]

30 g of styrene monomer

45 g of divinylbenzene monomers

75 g dichlorobenzene (swelling agent)

Hexyl alcohol (precipitant) 75 g

Benzoyl peroxide (initiator) 0.75 g

Benzoylper as a polymerization initiator in a mixed solution of 30 g of styrene monomer, 45 g of divinylbenzene monomer, 75 g of dichlorobenzene as a swelling agent, and 75 g of hexyl alcohol as a precipitant to prepare a carrier having a condition of varying swelling agent / precipitant ratio. After injecting a solution containing 0.75 g of oxide, a polymer carrier having a crosslinking degree of 33% was prepared in the same manner as in the above example, and platinum was supported on the prepared polymer carrier to prepare a hydrophobic styrene polymer catalyst suitable for hydrogen isotope exchange reaction. Prepared. The ratio of the swelling agent / precipitant in this case was 1/1.

In the above examples and comparative examples, styrene monomer and divinyl benzene monomer are washed three times with NaOH solution and distilled water to remove the polymerization inhibitor included in the reagent purchase, stored at 5 ° C. or less, and used as needed. It was.

1 shows an embodiment (- -) And Comparative Example (- It shows the pore distribution of the polymer polymer which is the catalyst carrier prepared in-). In the embodiment, the micropores are evenly distributed from the macropores, but in the comparative example, the macropores are distributed much.

In Figure 2 the embodiment (- -) Catalyst and Comparative Example (- This is a graph comparing the reaction rate constant as a result of hydrogen isotope exchange reaction using gaseous-vapor catalyst. As shown in the experimental results, the reaction rate constant was higher in the case of the hydrogen isotope exchange reaction in the gas phase-vapor phase-liquid phase than in the catalyst of the comparative example in which the macropores were relatively distributed. It can be seen.

As described above, the hydrophobic catalyst prepared by the method of the present invention uniformly distributes the catalyst supported in the pores by uniformly distributing the pores formed in the polymer carrier, thereby increasing the efficiency of the catalyst as well as gas phase- The rate of reaction in the vapor-liquid phase, in particular hydrogen isotope exchange, can be greatly improved.

Claims (4)

In the method for preparing a hydrophobic polymer catalyst, a polymer carrier having a uniform pore distribution is prepared by carrying a monomer / solvent ratio of 0.3 to 1.0, a crosslinking degree of 30% or more, and a swelling agent / precipitator ratio of 0.5 or less, and then carrying a catalyst. Method for producing a hydrophobic catalyst (wet-proofed catalyst) having a uniform pore distribution. The method of claim 1, wherein the polymer carrier is a styrene-based polymer carrier and the catalyst is a platinum group metal. The method according to claim 1, wherein the swelling agent is an aromatic compound containing benzene and toluene and the precipitant is saturated hydrocarbon alcohols. A catalyst for hydrogen isotope exchange reaction, characterized in that the pore distribution prepared according to the method of claim 1, 2 or 3 consists of an even hydrophobic catalyst.