KR20120037204A - Palladium catalyst supported on heteropolyacid incorporated into mesoporous silica, preparation method thereof, and preparation method of hydrogen peroxide using said catalyst - Google Patents

Abstract

Disclosed are a catalyst for preparing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in the process of synthesizing a medium pore silica, and a method for producing the same.
According to the present invention, when a catalyst having a palladium loaded on a carrier in which heteropoly acid is introduced in the process of synthesizing a medium pore silica is used to prepare hydrogen peroxide, the amount of heteropoly acid used and the step of preparing the catalyst can be reduced and improved even under conditions without an acid additive. Hydrogen peroxide selectivity and hydrogen peroxide yield can be obtained.

Description

Palladium-supported catalyst, a method for preparing the same, and a method for producing hydrogen peroxide using the catalyst in a carrier in which a heteropoly acid is introduced in the process of synthesizing medium-porous silica, preparation method according to the preparation method of hydrogen, and preparation method of hydrogen peroxide using said catalyst}

The present invention relates to a catalyst for preparing hydrogen peroxide in which palladium is supported on a carrier in which heteropoly acid is introduced in a medium-porous silica synthesis process, and a method for preparing the same, and more specifically, to a carrier in which heteropoly acid is introduced in a medium-porous silica synthesis process. The present invention relates to a catalyst for producing hydrogen peroxide having a high hydrogen peroxide yield while reducing the amount of heteropoly acid used and the step of preparing the catalyst.

Hydrogen peroxide has a strong oxidizing power and is known as an oxidizing agent that does not decompose with water and hydrogen and pollute the environment. Hydrogen peroxide is thus used in various fields such as pulp, paper, textile industry and wastewater treatment. Hydrogen peroxide is currently produced by the Anthraquinone Process, but this process has been a major factor in reducing the price competitiveness of hydrogen peroxide, due to the large number of reaction steps required and the separation and purification of hydrogen peroxide. Accordingly, research on the reaction for producing hydrogen peroxide directly from hydrogen and oxygen is underway.

Direct production of hydrogen peroxide proceeds mainly using noble metal catalysts such as palladium, gold and platinum. In addition, additives have been used to improve the selectivity of hydrogen peroxide. In general, in order to suppress the decomposition of hydrogen peroxide, a liquid inorganic acid such as sulfuric acid and phosphoric acid is added to a solvent to proceed with the reaction, and water is formed from hydrogen and oxygen. Halogen ions are added to the solvent or catalyst to inhibit the reaction [VR Choudhary, P. Jana, Appl. Catal. A, vol. 352, 35 (2009)].

Acid and halogen additives serve to improve the selectivity of hydrogen peroxide, but also cause corrosion of the reaction apparatus and dissolve the metal such as palladium supported on the carrier, thereby deactivating the catalyst, and separating and purifying hydrogen peroxide. To need it. Since the direct manufacturing reaction of hydrogen peroxide is to secure the price competitiveness of hydrogen peroxide, it is not reasonable to prepare a hydrogen peroxide from hydrogen and oxygen and then separate and purify it. Therefore, there is a need to develop a catalyst that exhibits high activity in the hydrogen peroxide direct production reaction while minimizing the use of acid and halogen additives.

Heteropoly acids are solid acids with strong acid properties and are used as catalysts for various acid catalyst reactions. Heteropolyacids have a variety of structures depending on the composition ratio of the central element and the isotope, so the ratio of the central element: isotope is 1 Keggin structure with 1: 12, Wells-Dawson structure with 2: 18 and Anderson with 1: 6 Structure, etc. [IV Kozhevnikov, Chem. Rev., Vol. 98, p. 171 (1998)]. Among these, it is widely used for the actual catalytic reaction and the best known structure is the heteropoly acid of Keggin structure.

Heteropoly acid of the Keggin structure is known to be able to form a variety of compounds according to the change of the central element or isotope, representative examples are 12- tungstoic acid (H ₃ PW ₁₂ O ₄₀ ), 12- molybdate phosphoric acid (H ₃ PMo ₁₂ O ₄₀ ), 12-tungstosilonic acid (H ₄ SiW ₁₂ O ₄₀ ), and 12-molybdosilic acid (H ₄ SiMo ₁₂ O ₄₀ ). In addition, heteropolyacids have acidic properties depending on the type of central element or isotope, and the acid strength of the heteropolyacids of the Keggin structure mentioned above is 12- tungstoic acid> 12- tungstosilonic acid> 12- molybdoic acid> 12 -Molybdosilic acid decreases in order [CL Hill, CM Prosser-McCartha, Coord. Chem. Rev., vol. 143, p. 407 (1995) / IV Kozhevnikov, Chem. Rev., Vol. 98, p. 171 (1998)].

US Pat. No. 5,320,821 discloses a process for producing hydrogen peroxide directly from hydrogen and oxygen using a catalyst using palladium and insoluble heteropolyacids. In this patent, an insoluble heteropolyacid was first prepared, and then used as a carrier to carry palladium by impregnation. In this patent, since insoluble heteropolyacid itself is directly used as a carrier without using a carrier, a catalyst supporting palladium in an insoluble heteropolyacid has a problem that it is difficult to separate the catalyst from the reaction solvent due to the small particle size of about 10 nm. .

Korean Patent Publication No. 2010-37411 discloses a method for producing hydrogen peroxide using a palladium substituted insoluble heteropolyacid catalyst. Although insoluble heteropolyacids are used as carriers in the above patents, palladium is replaced by ion exchange rather than by impregnation to produce a catalyst. In this patent, it is supported by a method of substituting palladium, thereby increasing the dispersibility of palladium and reducing the production step of the catalyst.

In the present invention, the addition of heteropoly acid to the synthesis process of the mesoporous silica can reduce the amount of heteropoly acid used and the step of preparing the catalyst, and provide improved hydrogen peroxide selectivity and hydrogen peroxide yield even under an acid additive.

One aspect of the present invention is to provide a catalyst for producing hydrogen peroxide in which palladium is supported on a carrier in which heteropoly acid is introduced in the process of synthesizing a medium pore silica.

Another aspect of the present invention is a method of preparing a catalyst for producing hydrogen peroxide in which a palladium is supported on a carrier in which a heteropoly acid is introduced in a medium pore silica synthesis process, the method comprising the steps of: (a) adding a heteropoly acid to the synthesis process of a medium pore silica; (b) It is an object of the present invention to provide a catalyst for producing hydrogen peroxide comprising the step of impregnating palladium on the medium-sized pore silica into which the heteropolyacid formed through step (a) is introduced.

Another aspect of the present invention is to provide a method for preparing hydrogen peroxide from hydrogen and oxygen using a catalyst for preparing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in a medium pore silica synthesis process.

However, technical problems to be achieved by the present invention are not limited to the above-mentioned problems, and other technical problems will be clearly understood by the average technician from the following description.

According to an aspect of the present invention, there is provided a catalyst for producing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in a medium pore silica synthesis process.

According to another aspect of the present invention, a method for preparing a hydrogen peroxide preparation catalyst having palladium supported on a carrier in which a heteropoly acid is introduced in the process of synthesizing medium pore silica, comprising: (a) adding a heteropoly acid to the process of synthesizing medium pore silica; (b) It provides a catalyst for producing hydrogen peroxide comprising the step of impregnating palladium on the medium-sized pore silica into which the heteropolyacid formed through step (a) is introduced.

According to another aspect of the present invention, there is provided a method for producing hydrogen peroxide from hydrogen and oxygen by using a catalyst for producing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in the process of synthesizing a medium pore silica.

Other specific details of embodiments of the present invention are included in the following detailed description.

The catalyst in which palladium is supported on a carrier in which heteropoly acid is introduced in the process of synthesizing the mesoporous silica of the present invention reduces the amount of heteropoly acid and the step of preparing the catalyst by adding heteropolyacid to the process of synthesizing the mesoporous silica, and does not use an acid additive. Also provides improved hydrogen peroxide selectivity and hydrogen peroxide yield.

FIG. 1 is a graph showing a change in catalytic activity according to a heteropoly acid content change in a catalyst in which palladium is supported on a carrier in which a heteropoly acid is introduced during the synthesis of MCF in a hydrogen peroxide direct production reaction.
FIG. 2 is a graph showing a change in catalytic activity according to a heteropoly acid content change in a catalyst in which palladium is supported and reduced on a carrier in which a heteropoly acid is introduced during the synthesis of MCF in a hydrogen peroxide direct production reaction.
FIG. 3 is a graph showing the reaction activity of a catalyst in which palladium is supported and reduced on MCF and a catalyst in which heteropoly acid is introduced and impregnated with palladium on a carrier in which MCF is synthesized in the process of directly producing hydrogen peroxide.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

One aspect of the present invention relates to a catalyst for producing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in a medium pore silica synthesis process.

As in US Pat. No. 5,320,821, when an insoluble heteropoly acid is used as a carrier, its particle size is about 10 nm, and when a palladium supported catalyst is prepared using this as a carrier, the catalyst is removed from the reaction solvent after the reaction due to the catalyst particle size that is too small. The process of separation is not easy.

However, the catalyst of the present invention fixes the heteropolyacid to the mesoporous silica by adding the heteropolyacid to the synthesis of the mesoporous silica. Since the particle size of the mesoporous silica is about the micron, the catalyst can be easily separated from the reaction solvent. , Catalyst recovery and reuse are advantageous.

In the present invention, since the carrier is introduced with a heteropoly acid in the process of synthesizing the medium pore silica, the dispersion of palladium is high. Since the surface area (typically 400 m ² / g) of the carrier in which the heteropoly acid is introduced during the process of synthesizing the mesoporous silica is large compared to the surface area of the insoluble heteropoly acid (typically 100-150 m ² / g), even when supported by impregnation, Palladium dispersion can be maintained.

In addition, in the present invention, by adding heteropoly acid to the synthesis process of the medium pore silica, only the medium pore silica is synthesized and then the process of supporting the heteropoly acid on the medium pore silica is reduced to one step, thereby reducing the time and cost of the catalyst preparation and reproducibility of the catalyst preparation. Can increase.

In addition, in the present invention, the heteropolyacid is added to the medium pore silica synthesis process, thereby preventing the heteropolyacid from being easily dissolved in the polar solvent. Therefore, in the case of supporting heteropoly acid separately after synthesizing medium pore silica, a process of substituting hydrogen ions with +1 valent cations for forming an insoluble heteropoly acid is necessary, but is not required in the present invention.

In addition, in the present invention, it is possible to maintain a high degree of dispersion of the heteropolyacid by adding a heteropolyacid during the synthesis of the medium pore silica, and as mentioned above, since the hydrogen ions of the heteropolyacid do not have to be substituted with +1 valent cation, a small amount of heteropolyacid It is also effective because it can show excellent effects.

The mesoporous silica is not particularly limited and may include mesoporous silica commonly used for any purpose, but according to one embodiment of the present invention, MCM-41, MCM-48, MSU-1, SBA- 15, or MCF is preferred.

According to one embodiment of the present invention, the heteropolyacid may use a heteropolyacid having a Keggin structure such as 12-tungstoic acid, 12-molybdolic acid, 12-tungstosilonic acid, or 12-molybdosilic acid, preferably Can use 12- tungstophosphoric acid.

However, the heteropolyacid is not limited thereto, and may further include a heteropolyacid commonly used for any purpose.

Another aspect of the present invention is a method of preparing a catalyst for producing hydrogen peroxide in which a palladium is supported on a carrier in which a heteropoly acid is introduced in a medium pore silica synthesis process, the method comprising the steps of: (a) adding a heteropoly acid to the synthesis process of a medium pore silica; (b) It provides a catalyst for producing hydrogen peroxide comprising the step of impregnating palladium on the medium-sized pore silica into which the heteropolyacid formed through step (a) is introduced.

According to one embodiment of the present invention, the mass ratio of medium pore silica to heteropolyacid is preferably 1: 0.01 to 0.5.If the mass ratio of heteropoly acid to medium pore silica is less than 0.01, the content of heteropoly acid may be reduced due to the low content of heteropoly acid. There is a problem that the effect of improving the acid properties is too small, on the contrary, if it is larger than 0.5, the support of heteropoly acid is inefficient due to the use of excess heteropoly acid, and the pore formation of medium pore silica is not smoothly performed. According to one embodiment of the present invention, the mass ratio of more preferred medium pore silica: heteropoly acid is 1: 0.1 to 0.3.

According to one embodiment of the present invention, the palladium is used in the form of a palladium precursor, the precursor is palladium chloride (Palladium Chloride: PdCl ₂ ), Palladium nitrate (Palladium Nitrate: Pd (NO ₃ ) ₂ ), Palladium sulfate (Palladium) Sulfate: Pd (SO ₄ ) ₂ ), Palladium Acetate (P ₂ H ₃ O ₂ ) ₂ Pd) At least one selected from the group consisting of. According to one embodiment of the present invention, it is preferable to use palladium nitrate having high solubility in aqueous solution.

According to one embodiment of the present invention, the mass ratio of the carrier to the palladium precursor in which the heteropoly acid is introduced in the medium pore silica synthesis is preferably 1: 0.004 to 0.05, and the palladium to the carrier in which the heteropoly acid is introduced to the medium pore silica synthesis If the mass ratio of the precursor is less than 0.004, there is a problem that the active point is too small with a low palladium content. On the contrary, if the mass ratio is larger than 0.05, the supporting of palladium is inefficient due to the excess palladium. According to one embodiment of the present invention, the mass ratio of the carrier to the palladium precursor in which the heteropoly acid is introduced in a more preferable medium pore silica synthesis process is 1: 0.008 to 0.015.

In another aspect of the present invention, a method of preparing a catalyst for preparing hydrogen peroxide in which palladium is supported and reduced on a carrier in which heteropoly acid is introduced in the process of synthesizing medium pore silica, comprising: (a) adding a heteropoly acid to the process of synthesizing medium pore silica; (b) impregnating palladium on the medium pore silica into which the heteropoly acid is introduced in step (a); (c) reducing palladium supported on a carrier into which a heteropoly acid is introduced in the process of synthesizing the mesoporous silica formed through the step (b).

The reducing agent used to reduce the palladium supported on the carrier in which the heteropoly acid is introduced in the medium pore silica synthesis process is not particularly limited, but according to another embodiment of the present invention, a hydrazine (Hydrazine: NH ₂ NH ₂ ) as a reducing agent It is possible to use an aqueous solution or a method of flowing a hydrogen mixed gas at a temperature of 200 ~ 500 ℃. Using a hydrazine solution requires additional processes of washing, filtration and drying, and since the hydrazine solution is a highly toxic material, it is preferable to use a hydrogen mixed gas.

Another aspect of the present invention is a method for producing hydrogen peroxide from hydrogen and oxygen using a catalyst in which palladium is supported on a carrier in which heteropoly acid is introduced in the process of synthesizing a medium pore silica.

The hydrogen peroxide direct production reaction may be carried out in a liquid phase reaction using methanol, ethanol or water as a solvent (reaction medium), but preferably methanol.

The reaction proceeds in a high temperature and high pressure reactor (Autoclave), it is preferable to maintain a constant reaction temperature through a heating device surrounding the outer wall of the reactor and a thermometer and cooling device installed inside the reactor.

The reactants hydrogen and oxygen are each used as a mixed gas diluted with nitrogen to reduce the explosion risk. Preferably, the hydrogen mixed gas ratio is hydrogen: nitrogen molar ratio of 1: 3, and the oxygen mixed gas is oxygen: nitrogen molar ratio of 1 : 1

The reactant hydrogen mixed gas and oxygen mixed gas are preferably supplied directly to the solvent using a dip tube that can be contained in the solvent in order to improve solubility in the solvent. The hydrogen mixed gas may flow at a flow rate of 14.7-22.0 ml / min, and the oxygen mixed gas may flow at a flow rate of 22.0-29.4 ml / min. More preferably, the hydrogen mixed gas is maintained at 20.4 ml / min and the oxygen mixed gas is maintained at 23.3 ml / min, so that the hydrogen: oxygen: nitrogen molar ratio is 1: 2.3: 5.4.

Hydrogen mixed gas and oxygen mixed gas are flowed at a constant flow rate, and the overall reaction pressure is controlled using a BPR (Back Pressure Regulator). The reaction pressure is measured through a pressure gauge connected to the reactor. The reaction pressure is preferably maintained at 1 to 15 atm, preferably at 10 atm, and the reaction temperature is preferably maintained at 20 to 30 ° C.

The reaction for producing hydrogen peroxide directly from hydrogen and oxygen is important to reduce the material diffusion resistance to a minimum by increasing the stirring speed, it is preferable to maintain the stirring speed at 800 ~ 1200 rpm.

According to one embodiment of the present invention, in the hydrogen peroxide production method, a halogen additive may be used.

The halogen additive for the hydrogen peroxide direct production reaction includes chloride, bromide salt, and the like, and preferably, bromine salts such as sodium bromide (NaBr) and potassium bromide (KBr).

The concentration of sodium bromide used as the halogen additive in the reaction is preferably 0 to 300 ppm, more preferably 100 ppm based on the mass of methanol used as the solvent.

The amount of the catalyst in which palladium is supported on the carrier in which the heteropoly acid is introduced in the process of synthesizing the mesoporous silica used in the reaction is preferably such that the amount of palladium in the catalyst is 0.006 to 0.08% by weight based on the mass of the solvent, more preferably. Preferably 0.008% by weight.

Hereinafter, a preparation example of a catalyst having palladium impregnated on a carrier having heteropoly acid introduced therein in the process of synthesizing medium-porous silica, and a preparation having a palladium impregnated and supported on a carrier having heteropoly acid introduced therein in the process of synthesizing medium-porous silica For example, Comparative Preparation Example of Catalyst Impregnated with Palladium on Small Pore Silica without Heteropoly Acid by Impregnation and Reduction, Example Using Catalysts as Catalysts for Directly Producing Hydrogen Peroxide Using Hydrogen and Oxygen as Reactants Through the comparative example will be described in more detail the present invention. However, 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 reaction time for comparing the activity of each catalyst in the reaction for producing hydrogen peroxide directly from hydrogen and oxygen was fixed at 6 hours.

Manufacturing example  One : MCF In the synthesis process of Heteropolyacids  Introduced On the carrier  Palladium By impregnation method Supported  Preparation of the catalyst

35% aqueous hydrochloric acid solution was added to distilled water at 40 ° C. to 1.6 M, and the mass ratio of distilled water and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (PEO-PPO-PEO Triblock Copolymer) was 1: 0.07. To this end, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer was dissolved. Then, the heteropolyacid is dissolved in a small amount of distilled water so that the mass ratio of distilled water and heteropoly acid is 1: 0.0002, and the mixture is stirred rapidly for 6 hours, and then distilled water and 1,3,5-trimethylbenzene (1,3,5-Trimethylbenzene 1,3,5-trimethylbenzene was added and stirred for 1 hour so that the mass ratio of c) was 1: 0.01. Then, tetraethylorthosilicate was added so that the mass ratio of distilled water and tetraethylorthosilicate was 1: 0.07 and stirred at 40 ° C. for 20 hours, and then synthesized without stirring at 130 ° C. for 20 hours. Thereafter, the solid component obtained through the filtration process was dried at room temperature and calcined at 550 ° C. for 5 hours.

Palladium was impregnated on a carrier in which heteropoly acid was introduced during the synthesis of MCF by using an aqueous solution of palladium nitrate so that the mass ratio of the carrier to which the heteropoly acid was introduced in the synthesis of MCF and the palladium precursor was 1: 1. It was dried for 12 hours and then calcined at 500 ° C. for 3 hours. In the synthesis of MCF prepared through the above process, a catalyst in which palladium was impregnated on a carrier having heteropoly acid introduced therein is a catalyst of heteropolyacid 12-tungstoic acid (H ₃ PW ₁₂ O ₄₀ , weak in HPW) as shown in Table 1. It is expressed as PdO / HPW-MCF-1.0 using the inner content (% by weight). In this case, the number after the catalyst name means the amount of HPW introduced into the catalyst (% by weight).

Manufacturing example  2 ~ 7: MCF In the synthesis process of Heteropolyacids  Introduced On the carrier  Palladium By impregnation method Supported  Preparation of the catalyst

In Production Examples 2 to 7, the mass ratio of distilled water and heteropoly acid was 1: 0.001, 1: 0.002, 1: 0.003, 1: 0.004, 1: 0.005, 1: 0.006, except that Prepared. The catalyst in which palladium was impregnated on a carrier in which heteropoly acid was introduced in the synthesis of MCF prepared through the above process was used in the catalyst (% by weight) of 12-tungstoic acid (HPW), which is a heteropoly acid, as shown in Table 1 below. Indicated.

[Table 1]

Manufacturing example  8 ~ 14: MCF In the synthesis process of Heteropolyacids  Introduced On the carrier  Palladium is impregnated Supporting  Preparation of Reduced Catalyst

A catalyst in which palladium was impregnated and reduced on a carrier into which a heteropoly acid was introduced in the synthesis of MCF was prepared by reducing palladium after the same process as in Preparation Examples 1 to 7. In the synthesis of MCF, a catalyst loaded with a heteropoly acid was impregnated with a palladium impregnated method into a quartz reactor installed in an electric furnace, and nitrogen and hydrogen were flown at 200 ° C. at a flow rate of 20 ml / min and 5 ml / min, respectively. It was reduced for 2 hours while feeding. In the synthesis of MCF prepared through the above procedure, a catalyst in which palladium was impregnated and reduced on a carrier having heteropoly acid introduced therein is shown in Table 2 below.

TABLE 2

compare Manufacturing example  One : Heteropolyacids  Unadded MCF Palladium on By impregnation method Supporting  Preparation of Reduced Catalyst

The preparation process of the catalyst which carried the palladium impregnated and reduced the prepared MCF for comparison is as follows. Palladium was impregnated in MCF using an aqueous solution of palladium nitrate so that the mass ratio of MCF and palladium precursor was 1: 0.01, dried at 80 ° C. for 12 hours, and then calcined at 500 ° C. for 3 hours. Thereafter, the catalyst loaded with palladium impregnated in MCF was injected into a quartz reactor installed in an electric furnace, and reduced for 2 hours while supplying nitrogen and hydrogen at a flow rate of 20 ml / min and 5 ml / min at 200 ° C., respectively. The catalyst which was supported by palladium by the impregnation method and reduced by the MCF prepared through the above process is represented as Pd ⁰ / MCF.

Example  1 ~ 7: MCF In the synthesis process of Heteropolyacids  Introduced On the carrier  Palladium By impregnation method Supported  Process for producing hydrogen peroxide by catalyst

In the synthesis of MCF prepared in Preparation Examples 1 to 7 using a catalyst in which palladium was impregnated on a carrier in which heteropoly acid was introduced, a reaction of directly preparing hydrogen peroxide from hydrogen and oxygen was performed. Corresponds to ~ 7.

The reaction for producing hydrogen peroxide directly from hydrogen and oxygen was carried out using methanol as a solvent and a trace amount of a halogen additive, and hydrogen and oxygen diluted with nitrogen were used as reactants, and the pressure of the reactor was kept constant.

6.32 mg of sodium bromide was added together with 80 ml of methanol in a 210 ml high temperature high pressure reactor, 1 g of a catalyst was added, and the reaction temperature was adjusted to 28 ° C. Hydrogen mixed gas (hydrogen: nitrogen molar ratio = 1: 3) and oxygen mixed gas (oxygen: nitrogen molar ratio = 1: 1) were supplied at flow rates of 20.4 ml / min and 23.3 ml / min, respectively, The reaction pressure was kept constant at 10 atmospheres. The reaction was considered to start when the pressure was set to 10 atm, and the activity of the catalyst was compared using the reaction result at 6 hours after the start of the reaction.

The conversion rate of hydrogen was found from the calculation results of hydrogen consumption using gas chromatography, and the selectivity of hydrogen peroxide was calculated using the amount of hydrogen peroxide measured using an iodine titration. In the reaction for producing hydrogen peroxide directly from hydrogen and oxygen, the conversion of hydrogen, selectivity of hydrogen peroxide, and yield of hydrogen peroxide were calculated using the following equations.

Example  8 ~ 14: MCF In the synthesis process of Heteropolyacids  Introduced On the carrier  Palladium By impregnation method Supporting  Process for producing hydrogen peroxide with reduced catalyst

Hydrogen peroxide from hydrogen and oxygen was prepared in the same manner as in Examples 1 to 7 by using a catalyst in which palladium was impregnated and reduced on a carrier in which heteropoly acid was introduced in the synthesis process of MCF prepared according to Preparation Examples 8 to 14. The reaction was carried out to prepare directly, these correspond to Examples 8-14, respectively.

Comparative example  One : Heteropolyacids  Unadded MCF Palladium on By impregnation method Supporting  Process for producing hydrogen peroxide with reduced catalyst

The reaction of directly preparing hydrogen peroxide from hydrogen and oxygen was carried out in the same manner as in Examples 1 to 14, except that the catalyst prepared by carrying out palladium impregnation on the MCF prepared by Comparative Preparation Example 1 and using a reduced catalyst was used. .

MCF In the synthesis process of Heteropoly acid (HPW)  Introduced On the carrier  Palladium By impregnation method Supported  In the catalyst Of heteropolyacids (HPW)  Changes in Catalyst Activity According to Content

According to Preparation Examples 1 to 7, a reaction in which hydrogen peroxide was directly prepared from hydrogen and oxygen was carried out by using a catalyst in which palladium was impregnated on a carrier into which a heteropoly acid was introduced in the synthesis of MCF. The results are shown in FIG. It was. The reaction for producing hydrogen peroxide directly from hydrogen and oxygen was carried out by adding 6.32 mg of sodium bromide with 80 ml of methanol and 1 g of catalyst in a 210 ml high temperature high pressure reactor as shown in Examples 1-7. Next, the hydrogen mixed gas and the oxygen mixed gas were supplied at a flow rate of 20.4 ml / min and 23.3 ml / min, respectively, and the reaction conditions were performed at 10 atmospheres and 28 ° C., and the catalytic reaction activity was observed at 6 hours from the start of the reaction.

1, it can be seen that the hydrogen peroxide direct production reaction activity varies depending on the content of heteropoly acid (HPW). The hydrogen conversion was maintained at 66.8-71.4% without being affected by the change in the heteropolyacid content, and the hydrogen peroxide selectivity increased with the increase of the heteropolyacid content in the range of 14.2-45.7%.

As a result, the hydrogen peroxide yield showed a tendency to increase and decrease with the content of the heteropoly acid in the range of 10.0 to 3.31%. Although the activity varies depending on the content of heteropolyacid, the catalyst in which palladium is impregnated on a carrier in which heteropoly acid is introduced during the synthesis of MCF is higher than the palladium catalyst supported on a common commercial carrier without an acid additive. , Hydrogen peroxide selectivity and hydrogen peroxide yield.

MCF In the synthesis process of Heteropolyacids  Introduced On the carrier  Palladium By impregnation method Supporting  In the reduced catalyst Heteropolyacid  Changes in Catalyst Activity According to Content

According to Preparation Examples 8 to 14, hydrogen peroxide was directly produced from hydrogen and oxygen by using a catalyst in which palladium was impregnated and reduced on a carrier having heteropoly acid introduced therein in the synthesis of MCF. Shown in

According to Figure 2, the hydrogen conversion was maintained constant without being significantly affected by the heteropoly acid content of 85.5 ~ 88.1%, hydrogen peroxide selectivity increased to decrease with the content of heteropoly acid to 31.8 ~ 59.3%. Therefore, the hydrogen peroxide yield also increased and decreased with increasing heteropolyacid content in the range of 28.1-51.6%.

Although the activity was changed according to the content of the heteropolyacid, the catalyst in which the palladium was impregnated and reduced in the carrier in which the heteropolyacid was introduced during the synthesis of MCF was reduced in the reaction conditions without using an acid additive. Much better results were obtained in hydrogen conversion, hydrogen peroxide selectivity, and hydrogen peroxide yield.

According to the comparison of FIG. 1 and FIG. 2, it can be seen that the tendency of the hydrogen peroxide direct production reaction activity to change according to the content of heteropoly acid does not change depending on the redox state of palladium.

In addition, it can be seen that the catalyst which was supported by the impregnation method of palladium on the carrier introduced with heteropoly acid in the synthesis of MCF showed higher hydrogen conversion rate, hydrogen peroxide selectivity, and hydrogen peroxide yield than the catalyst which was not reduced.

However, the catalyst of the present invention exhibited better hydrogen conversion, hydrogen peroxide selectivity and hydrogen peroxide yield than the palladium catalyst supported on a common commercial carrier even in the case of a palladium supported catalyst which was not reduced.

Heteropolyacid  On medium pore silica depending on addition Supporting  Activity Changes of Reduced Palladium Catalysts

In the synthesis of MCF prepared in Preparation Example 13, a catalyst (Pd ⁰ /HPW-MCF-20.0), which was supported by a method of impregnating palladium on a carrier having heteropoly acid introduced therein and reduced therein, was subjected to hydrogen peroxide from hydrogen and oxygen according to Example 13. As a result of the direct preparation reaction, palladium was impregnated and supported on the carrier in which heteropoly acid was introduced during the synthesis of MCF, and the hydrogen peroxide yield was the highest among the catalysts. In order to make a comparison with this, a catalyst (denoted as Pd ⁰ / MCF in FIG. 3), prepared by carrying out palladium impregnation on MCF by Comparative Preparation Example 1 and reduced, was prepared, and hydrogen peroxide from hydrogen and oxygen according to Comparative Example 1. The reaction was carried out to prepare directly, the results are shown in Figure 3 together with the results of Example 13.

According to FIG. 3, the catalyst (Pd ⁰ / MCF) supported and reduced by only palladium impregnation on MCF without adding heteropoly acid showed high hydrogen conversion, while showing very low hydrogen peroxide selectivity, and also low hydrogen peroxide yield.

However, it was found that the catalyst (Pd ⁰ /HPW-MCF-20.0) supported by the palladium impregnation method and reduced by the heteropoly acid-introduced carrier in the synthesis of MCF improved hydrogen peroxide selectivity and significantly increased hydrogen peroxide yield. This shows that the addition of heteropolyacid to the mesoporous silica can greatly improve the hydrogen peroxide selectivity and hydrogen peroxide yield in the reaction for producing hydrogen peroxide directly from hydrogen and oxygen.

Claims (8)

A catalyst for producing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in the process of synthesizing a medium pore silica. The catalyst for producing hydrogen peroxide according to claim 1, wherein the medium pore silica is MCM-41, MCM-48, MSU-1, SBA-15, or MCF. As a method of preparing a catalyst for producing hydrogen peroxide in which palladium is supported on a carrier in which a heteropoly acid is introduced in the process of synthesizing a medium pore silica,
(a) adding heteropolyacid to the synthesis of medium pore silica;
(b) a method for producing a hydrogen peroxide catalyst comprising the step of impregnating palladium on a medium-sized pore silica into which the heteropolyacid formed through step (a) is introduced. The method of claim 3, wherein
(c) a catalyst for producing hydrogen peroxide, further comprising the step of reducing palladium supported on the medium-sized pore silica into which the heteropolyacid formed through step (b) is introduced. The catalyst for producing hydrogen peroxide according to claim 3 or 4, wherein the mass ratio of the medium pore silica to the heteropolyacid is from 1: 0.01 to 0.5, and the mass ratio of the medium pore silica to the palladium precursor into which the heteropoly acid is introduced is 1: 0.004 to 0.05. Manufacturing method. The method of claim 3 or 4, wherein the palladium is used in the form of a palladium precursor, the precursor is palladium chloride (Palladium Chloride: PdCl ₂ ), palladium nitrate (Palladium Nitrate: Pd (NO ₃ ) ₂ ), palladium sulfate ( Palladium Sulfate: Pd (SO ₄ ) ₂ ), Palladium acetate (Palladium Acetate: (C ₂ H ₃ O ₂ ) ₂ Pd) The catalyst production method for producing hydrogen peroxide, characterized in that at least one selected from the group consisting of. A method for producing hydrogen peroxide from hydrogen and oxygen using a catalyst for producing hydrogen peroxide in which palladium is supported on a carrier into which a heteropoly acid is introduced in the process of synthesizing a medium pore silica. The method of producing hydrogen peroxide from hydrogen and oxygen according to claim 7, wherein in the method for producing hydrogen peroxide, a halogen additive is used.

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