KR101804659B1 - Nanoparticle catalysis for synthesis of hydrogen peroxide and method of synthesis of hydrogen peroxide using the same - Google Patents

Abstract

The present invention relates to a nanoparticle catalyst for the production of hydrogen peroxide and a process for producing hydrogen peroxide using the catalyst. In the case of using the nanoparticle catalyst of the present invention, hydrogen peroxide can be directly produced by using expensive palladium efficiently, and the production yield of hydrogen peroxide is improved by controlling the optimal thickness of the shell.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a nanoparticle catalyst for preparing hydrogen peroxide and a method for producing hydrogen peroxide using the catalyst,

The present invention relates to a nanoparticle catalyst for the production of hydrogen peroxide and a process for producing hydrogen peroxide using the catalyst.

Hydrogen peroxide is used as a bleaching agent for pulp and fiber, disinfectant disinfectant, semiconductor cleaning liquid, oxidizer for water treatment process, and environmentally friendly oxidizer for chemical reaction (propylene oxide synthesis). As of 2009, 2.2 million tons of hydrogen peroxide are being produced annually, and the demand for hydrogen peroxide is expected to rise along with the increase in propylene oxide demand.

At present, hydrogen peroxide is generated through continuous oxidation and hydrogenation processes starting from anthraquinone-based compounds. In this case, a large amount of organic solvent is used and generated as waste. In addition, there is also a problem that the production of hydrogen peroxide requires a lot of energy consumption through a multi-stage continuous process and purification and concentration process after production.

Direct manufacturing process of synthesizing hydrogen peroxide by directly reacting hydrogen and oxygen has been attracting attention. This direct manufacturing process has been studied as an alternative process of commercial process because water is produced as a reaction by-product and use of organic solvent is low. The direct manufacturing process is simple in construction and can be manufactured where hydrogen peroxide is needed, thus greatly reducing the risk of explosion when storing and transporting hydrogen peroxide (Korean Patent Laid-Open Publication No. 2002-0032225).

However, since most of the catalyst systems for the production of hydrogen peroxide use precious metals such as palladium, and the prices of precious metals used are very high, technologies for efficiently using precious metals are required.

Korea Patent Publication No. 2002-0032225

It is an object of the present invention to provide a catalyst capable of increasing the production yield of hydrogen peroxide while efficiently using the hydrogen peroxide noble metal and a method for producing hydrogen peroxide using the same.

In order to achieve the above object, the present invention provides a core-shell structure, wherein the core is made of palladium (Pd), an alloy of palladium and gold (Pd-Au), or an alloy of palladium and platinum (Pd- Wherein the shell is made of silica (SiO ₂ ), the thickness of the shell is 38 to 53 nm, and is used for hydrogen peroxide production reaction from hydrogen and oxygen.

In one embodiment, the thickness of the shell may be 42 to 45 nm.

In another embodiment, the diameter of the core may be 1 to 30 nm.

The present invention also provides a method for producing hydrogen peroxide comprising the steps of supplying hydrogen and oxygen to a reactor including the nanoparticle catalyst for preparing hydrogen peroxide and a solvent and reacting the same.

In one embodiment, the solvent may be an alcohol solvent selected from the group consisting of methanol and ethanol, or a mixed solvent of the alcohol solvent and water.

Another embodiment may be that the solvent further comprises a halogen compound comprising bromine (Br), chlorine (Cl) or iodine (I).

In another embodiment, the solvent further comprises at least one acid selected from sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid

In another embodiment, the molar ratio of hydrogen and oxygen may be 1: 5 to 1:15.

Another embodiment may be to react by feeding additional nitrogen to the reactor.

In another embodiment, the reaction may be carried out at a pressure of 1 to 40 atm and at a temperature of 10 to 30 < 0 > C.

In the case of using the nanoparticle catalyst of the present invention, hydrogen peroxide can be directly produced by using expensive palladium efficiently, and the production yield of hydrogen peroxide is improved by controlling the optimal thickness of the shell.

FIG. 1 is a TEM photograph of the prepared nanoparticle catalysts of Examples 1 and 2 and Comparative Examples 1 to 4. FIG.
2 shows the production rate of hydrogen peroxide when hydrogen peroxide was directly produced from hydrogen and oxygen using the nanoparticle catalysts of Examples 1 and 2 and Comparative Examples 1 to 4. [
(The value obtained by dividing the mmol of hydrogen peroxide by the area of the palladium involved is shown on the left-hand side of the graph and divided by the mass of the palladium involved in the reaction on the right-hand axis. And the production of hydrogen peroxide can be directly compared per unit palladium area or per used palladium mass.)

The present invention relates to a nanoparticle catalyst for the production of hydrogen peroxide and a process for producing hydrogen peroxide using the catalyst. The present invention is characterized in that the production yield of hydrogen peroxide is improved by optimally adjusting the thickness of the shell, not the core.

When a shell is present in a chemical reaction, it is common that the conversion rate is lowered by interfering with mass transfer, and the lower the conversion rate, the lower the production yield. However, the inventors of the present invention have completed the present invention by suggesting an optimal thickness of the shell for improving the yield of hydrogen peroxide by confirming that the decomposition reaction of hydrogen peroxide produced is suppressed as the thickness of the shell is increased.

Hereinafter, the present invention will be described in detail.

The core comprises a core-shell structure, wherein the core comprises palladium (Pd), an alloy of palladium and gold (Pd-Au), or an alloy of palladium and platinum (Pd-Pt) ₂ ), wherein the shell has a thickness of 38 to 53 nm and is used for hydrogen peroxide production reaction from hydrogen and oxygen.

When the thickness of the shell is less than 38 nm, it is difficult to produce a nanoparticle catalyst having a core-shell structure, and a high hydrogen peroxide production yield can not be obtained due to the generated hydrogen peroxide decomposition reaction. When the thickness exceeds 53 nm, And the hydrogen conversion is very low. In addition, when the shell is thick, the hydrogen peroxide generated in the core (Pd) hardly escapes from the shell, thereby lowering the hydrogen peroxide productivity.

Preferably, the thickness of the shell may be in the range of 42 to 45 nm. If the thickness is within the above range, hydrogen peroxide decomposition reaction may be suppressed and a higher hydrogen peroxide production yield may be obtained.

The core may have a diameter of 1 to 30 nm. When the diameter of the core is less than 1 nm, synthesis is difficult. When the core diameter is more than 30 nm, the ratio of Pd exposed on the surface is reduced, which is effective to effectively use Pd.

The present invention also provides a method for producing hydrogen peroxide comprising the steps of supplying hydrogen and oxygen to a reactor including the nanoparticle catalyst for preparing hydrogen peroxide and a solvent and reacting the same.

The solvent may be an alcohol solvent selected from the group consisting of methanol and ethanol, or a mixed solvent of the alcohol solvent and water, preferably a mixed solvent of ethanol and water.

The solvent may further contain a halogen compound, preferably a halogen compound including bromine (Br), chlorine (Cl) or iodine (I), more preferably a bromine-containing halogen Compound. ≪ / RTI > Pd nanoparticles have energetic atoms, such as corners and edges. In these atoms, hydrogen and oxygen meet to form water, and the generated hydrogen peroxide The decomposition reaction dominates. When a halogen compound is added, the halogen anion is likely to adsorb to the energetic atom of palladium (Pd), thereby suppressing the negative reaction. However, the addition of an excess of halogen compound reduces the number of active sites of palladium (Pd) and reduces hydrogen conversion and hydrogen peroxide production.

The concentration of the halogen compound in the solvent may be 0 to 0.1 M, preferably 0 to 5 mM.

The solvent may further include an acid. The addition of an acid can greatly increase the yield of hydrogen peroxide by inhibiting the decomposition of the produced hydrogen peroxide. The acid may be one or more selected from sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), phosphoric acid (H ₃ PO ₄ ) and nitric acid (HNO ₃ ), preferably phosphoric acid.

The concentration of the acid in the solvent may be 0 to 0.1 M, preferably 0 to 3 M.

The reactants, hydrogen and oxygen, may be in a gaseous form and may be preferably fed directly to the solvent using a Dip Tube which may be contained in a solvent to improve the solubility in the solvent. The hydrogen gas may be flowed at a flow rate of 1 to 4 mL / min, and the oxygen gas may be flowed at a flow rate of 10 to 40 mL / min. More preferably, the hydrogen: oxygen molar ratio may be 1: 5 to 1: 15 while the hydrogen gas is maintained at 1.5 to 2.5 ml / min and the oxygen gas is maintained at 15 to 25 ml / min. The ratio of oxygen to hydrogen is 1: 1, but if the concentration of hydrogen is high, there is a danger of explosion. Therefore, if oxygen ratio is lower than 1: 5, there is danger of explosion. The range of the hydrogen: oxygen molar ratio is preferable because the concentration of supplied hydrogen is low and thus it is not efficient.

While the hydrogen gas and the oxygen gas are flowed at a constant flow rate, the entire reaction pressure is regulated using a BPR (Back Pressure Regulator), and the reaction pressure can be measured through a pressure gauge connected to the reactor. The reaction pressure is preferably maintained at 1 to 40 atm, preferably at normal pressure, and it may be preferable to conduct the reaction while maintaining the reaction temperature at 10 to 30 ° C.

Preferably, the reactor is further reacted by supplying nitrogen as a reactant. When nitrogen is used, it is possible to deviate from the explosion range even if the ratio of hydrogen to oxygen is set to 1: 1, and there is an advantage that it can be used without additional nitrogen separation when using oxygen in the air in the future.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the embodiments of the present invention described below are illustrative only and the scope of the present invention is not limited to these embodiments.

Example  1. Preparation of Pd @ S (10)

Ascorbic acid, polyvinylpyrrolidone (PVP), and potassium bromide (KBr) were dissolved in tertiary ultrapure water and stirred at 10 to 100 ° C for 10 minutes using a magnetic rod. Disodium tetrachloropalladate (Na ₂ PdCl ₄ ) solution was added and stirred at the same temperature for 3 hours with a magnetic stirrer to conduct reaction. Then, acetone was added to recover the nanoparticles produced by the centrifugal separator. Thereafter, the washed palladium nanoparticles were redispersed in ethanol and then water and ammonia water were added. After stirring for 3 hours, a silica precursor was added to synthesize a shell, and a silica precursor (TEOS, 10 ml) was added to make the shell thickness approximately 42 nm. After several washing steps, the nanoparticle catalyst (core: palladium, shell: silica) was prepared by heat treatment at 500 ° C. for 6 hours.

Example  2. Preparation of Pd @ S (15)

A nanoparticle catalyst (core: palladium, shell: silica) was prepared in the same manner as in Example 1, except that the amount of the silica precursor (TEOS) was changed to 15 m.

Comparative Example  1-4. Preparation of Pd @ S (5), Pd @ S (20), Pd @ S (25), Pd @ S (30)

A nanoparticle catalyst (core: palladium, shell: silica) was prepared in the same manner as in Example 1, except for the amount of the silica precursor. (5), Pd @ S (20), Pd @ S (25) and Pd @ S (30) according to the amount of silica precursor added (5, 20, 25 and 30 ml).

Experimental Example  1. Transmission electron microscopy

1, the catalysts of Examples 1 to 2 and Comparative Examples 1 to 4 were observed with a transmission electron microscope (TEM), and the average and standard deviation of the catalysts were measured. Respectively.

division Shell Thickness (nm) Comparative Example 1 Pd @ S (5) 37.4 Example 1 Pd @ S (10) 42.4 Example 2 Pd @ S (15) 44.3 Comparative Example 2 Pd @ S (20) 53.3 Comparative Example 3 Pd @ S (25) 57.9 Comparative Example 4 Pd @ S (30) 62.8

Experimental Example  2. Inductively coupled plasma An atomic emission spectrometer (ICP-AES)  Palladium content measurement and carbon monoxide chemisorption (CO- Chemisorption ) To measure the area of exposed Pd

Palladium contents of the nanoparticle catalysts of Examples 1 to 2 and Comparative Examples 1 to 4 were measured through ICP-AES analysis, and the results are shown in Table 2.

In addition, the palladium (Pd) exposed areas of the nano particle catalysts of Examples 1 to 2 and Comparative Examples 1 to 4 were measured through CO-Chemisorption analysis, and the results are shown in Table 2.

Specifically, the hydrogen peroxide synthesis reaction occurs in the exposed palladium, and the reaction result of the hydrogen peroxide synthesis reaction may vary depending on the exposed palladium area. The exposed area of the palladium is the palladium area (m ² / g- _cat ) and the area exposed per g of palladium (m ² / g - _Pd ). In the case of the core shell structure, there is a difference in palladium exposure area per g of palladium because the shell covers some palladium.

division Pd wt%
(ICP-AES) Area of exposed Pd
(CO-chemisorption) m ² / g- _cat m ² / g _-Pd Comparative Example 1 Pd @ S (5) 3.5 0.98 27.9 Example 1 Pd @ S (10) 1.8 0.65 36.7 Example 2 Pd @ S (15) 0.90 0.43 48.2 Comparative Example 2 Pd @ S (20) 0.68 0.42 61.3 Comparative Example 3 Pd @ S (25) 0.54 0.36 66.9 Comparative Example 4 Pd @ S (30) 0.49 0.24 49.2

Experimental Example  3. Production of hydrogen peroxide

Examples 1 to 2 and Comparative Examples 1 to 4 nano-catalyst of the reduction at 350 ℃ for 2 hours, the reaction solvent in a double jacket reactor (ultra pure water, 120 mL; ethanol (ethanol) 30 mL; and phosphoric acid (H ₃ PO ₄ ) 0.03 M, KBr 0.9 mM) and palladium (1 m) were reacted for 3 hours. The reaction temperature was maintained at 20 ° C and the pressure was maintained at 1 atm. The reaction gas (H ₂ / O ₂ = 1/10) was flowed constantly at 22 mL per minute. The hydrogen peroxide produced after the reaction was collected.

The concentration of hydrogen peroxide collected was measured by the following equation (1) using the iodometric titration method, and the amount of generated hydrogen peroxide was calculated by the following equation (2), and the result is shown in FIG.

As shown in FIG. 2, it was confirmed that the amounts of hydrogen peroxide produced were much higher than those of Comparative Examples 1 to 4 using the catalysts of Examples 1 and 2. This means that the use of a catalyst having a specific range of shell thickness (42 to 45 nm) has a high yield of hydrogen peroxide, and shell thickness control is considered to be a new variable for the hydrogen peroxide synthesis reaction.

Claims (10)

Having a core-shell structure,
Wherein the core is made of palladium (Pd), the shell is made of silica (SiO ₂ ), the thickness of the shell is 42 to 45 nm, the diameter of the core is 1 to 30 nm,
A catalyst for the production of hydrogen peroxide, characterized in that it is used for the hydrogen peroxide production reaction from hydrogen and oxygen. delete delete A process for producing hydrogen peroxide comprising the steps of: supplying hydrogen and oxygen to a reactor comprising the nanoparticle catalyst for producing hydrogen peroxide of claim 1 and a solvent. 5. The method of claim 4,
Wherein the solvent is an alcohol solvent selected from the group consisting of methanol and ethanol, or a mixed solvent of the alcohol solvent and water. 6. The method of claim 5,
Wherein the solvent further comprises a halogen compound comprising bromine (Br), chlorine (Cl) or iodine (I). 6. The method of claim 5,
Wherein the solvent further comprises at least one acid selected from sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid. 5. The method of claim 4,
Wherein the hydrogen and oxygen molar ratio is between 1: 5 and 1:15. 5. The method of claim 4,
Wherein the reactor is further fed with nitrogen to cause the reaction to proceed. 5. The method of claim 4,
Wherein the reaction is carried out at a pressure of 1 to 40 atm and at a temperature of 10 to 30 < 0 > C.

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