KR102623530B1 - Pt-Re catalyst for synthesis of hydrogen, and Method of preaparing hydrogen using the Pt-Re catalyst - Google Patents

Abstract

The present invention relates to a platinum-rhenium catalyst for hydrogen production and a method for producing hydrogen using the same. The catalyst for hydrogen production according to the present invention includes a porous carrier; Platinum supported in the pores of the porous carrier; and rhenium mixed with the platinum and supported in the pores.
According to the present invention, by supporting a mixture of platinum and rhenium on a porous carrier, the dehydrogenation activity is significantly improved even at low temperatures, making it possible to effectively obtain hydrogen from a liquid organic hydrogen storage body.

Description

Platinum-rhenium catalyst for hydrogen production and method for producing hydrogen using the same {Pt-Re catalyst for synthesis of hydrogen, and Method of preaparing hydrogen using the Pt-Re catalyst}

The present invention relates to a platinum-rhenium catalyst for hydrogen production and a method for producing hydrogen using the same.

As environmental pollution problems such as decreasing reserves of fossil fuels, pollutants generated during combustion, and global warming caused by carbon dioxide are becoming more serious, global interest in and demand for the development of alternative energy is explosively increasing.

As alternative energy sources, new and renewable energy such as wind power, tidal power, geothermal energy, hydrogen energy, and solar energy are in the spotlight. However, smooth supply and demand for new and renewable energy is difficult due to the instability of energy sources depending on time and the natural environment. In order to effectively replace conventional fossil fuels, development of technology for storing and supplying surplus energy is required to ensure a stable supply of energy.

From this perspective, hydrogen energy has various advantages, including the highest energy efficiency per unit mass, no harmful by-products during combustion, and the fact that water, the main source of hydrogen, is abundant in nature and is converted to water after use, making it advantageous for reuse. It's attracting attention. Moreover, hydrogen can be produced using other renewable energies such as solar energy and wind power, and can be widely applied not only to various energy sources but also to other industrial fields, including the petrochemical field, and is a key energy source of the future at home and abroad. is emerging.

In general, research and development of hydrogen energy is largely divided into hydrogen manufacturing, transportation (transportation), and storage fields. Hydrogen has excellent energy storage ability compared to mass, but low energy storage ability compared to volume, so hydrogen can be used efficiently. Storage technology is acting as the biggest obstacle to the practical use of hydrogen energy. For example, materials with a mass storage density of more than 10% by weight at 77 K are known, but the volumetric storage density of these materials is 40 g/L, which is low for actual use as a hydrogen storage material. . Therefore, research is being actively conducted on technologies to store as much hydrogen as possible in a storage medium that is as light and compact as possible.

To solve this problem, each country has invested a lot of money in research and development over the years, and the efficient storage methods of hydrogen that have been researched and developed so far are the CGH2 method, which compresses hydrogen using a pressure of 700 bar, and the CGH2 method, which stores liquid hydrogen by liquefying it at -253 ℃. There is an LH2 method. However, this pressurization or liquefaction method requires maintaining a low temperature, and the density of liquid hydrogen is also low at 712 kg/㎥.

As an alternative, materials with hydrogen storage capabilities, such as metal-organic frameworks (MOFs), carbon nanotubes, zeolites, porous organic or inorganic nanomaterials such as activated carbon, and metal hydrides, can be used to store hydrogen. Although it is being studied as a material that effectively stores energy, in the case of room temperature gas-phase hydrogen storage technology through physical absorption of MOFs and porous nanomaterials, the energy storage density is relatively low and the energy required for storage and desorption of hydrogen is relatively large. It has the disadvantage of being difficult to miniaturize and modularize.

For this reason, hydrogen storage technology by reversible catalytic hydrogenation/dehydrogenation reaction using liquid organic hydrogen carriers (LOHCs) has recently been attracting attention, and LOHC technology is 5% by weight as recommended by the U.S. Department of Energy (DOE). It can store more hydrogen and has the advantages of technology implementation due to a low pressure operating range and easy regeneration of the stored material. In addition, LOHC technology is positioned as an energy storage material that can be efficiently transported and stored using existing liquid fuel transportation and storage infrastructure due to the easy-to-handle physical properties and high energy density of liquid fossil fuels.

On the other hand, LOHC is a carrier that delivers hydrogen, and has the disadvantage that it must not deteriorate at all during the process of supplying hydrogen. If LOHC deteriorates during a high-temperature catalyst process, the purity of hydrogen may decrease due to by-products generated in the process, and the catalyst may also lose activity. Dibenzyltoluene is a form of three toluene molecules aggregated together and has excellent properties of being able to store 6.3 wt.% of hydrogen within the molecule. However, because massive molecules require a high temperature for the dehydrogenation process, perhydro-dibenzyltoluene generally undergoes the dehydrogenation process at a very high temperature of over 300℃. Therefore, deterioration or coking may occur during recycling. To prevent this, a catalyst showing high dehydrogenation activity even at low temperatures is required. However, currently known catalysts have a low dehydrogenation rate of perhydro-dibenzyltoluene below 270°C. It represents a very low level.

The present invention was devised to solve the above-mentioned problems, and the purpose of the present invention is to provide a catalyst for hydrogen production with improved dehydrogenation activity even at low temperatures by additionally introducing rhenium as a cocatalyst to the platinum-supported catalyst.

Another object of the present invention is to provide a method for producing a catalyst for hydrogen production with improved dehydrogenation activity even at low temperatures by additionally introducing rhenium as a cocatalyst to the platinum-supported catalyst.

Another object of the present invention is to provide a method for producing hydrogen using the catalyst for producing hydrogen.

In order to solve the above problems, the present invention

porous carrier; Platinum supported in the pores of the porous carrier; and rhenium mixed with the platinum and supported in the pores.

According to the present invention, the porous carrier may be activated carbon or aluminum oxide (Al ₂ O ₃ ).

According to the present invention, the activated carbon may be selected from the group consisting of graphene oxide, carbon black, and Vulcan.

According to the present invention, the platinum and the rhenium may be supported at a weight ratio of 1:0.1-1.

The present invention also includes the steps of (a) supporting a platinum precursor solution and a rhenium precursor solution in the pores of a porous carrier; and (b) reducing the porous carrier on which the platinum precursor solution and the rhenium precursor solution are supported.

According to the present invention, step (a) includes supporting a mixed solution of a platinum precursor solution and a rhenium precursor solution in the pores of the porous carrier; Drying the porous carrier on which the mixed solution is supported; and calcining the dried porous carrier.

According to the present invention, step (a) includes supporting a platinum precursor solution in the pores of the porous carrier; Drying the porous carrier on which the platinum precursor solution is supported; baking the dried porous carrier; and supporting a rhenium precursor solution in the pores of the calcined porous carrier.

According to the present invention, step (a) includes supporting a rhenium precursor solution in the pores of the porous carrier; Drying the porous carrier on which the rhenium precursor solution is supported; baking the dried porous carrier; and supporting a platinum precursor solution in the pores of the calcined porous carrier.

According to the present invention, the catalyst for hydrogen production may contain platinum and rhenium at a weight ratio of 1:0.1-1.

According to the present invention, step (a) may be performed by incipient wetness impregnation.

According to the present invention, the reduction in step (b) may be performed at 300 to 600° C. in a mixed gas atmosphere of hydrogen and nitrogen.

The present invention also includes the steps of mixing the catalyst for hydrogen production and a liquid organic hydrogen carrier (Liquid Organic Hydrogen Carrier, LOHC); and performing a dehydrogenation reaction after the mixing.

According to the present invention, the liquid organic hydrogen storage includes perhydro-Dibenzyltoluene, cyclohexane, methyl cyclohexane, decalin, benzyl toluene, It may be selected from the group consisting of dibenzyl toluene, perhydro-N-ethylcarbazole, and 2-[(N-methylcyclohexyl)methyl]piperidine.

According to the present invention, the dehydrogenation reaction can be performed at a temperature of 250 to 300 ° C. for 2 to 4 hours.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to this, terms or words used in this specification and claims should not be interpreted in their usual, dictionary meaning, and the inventor may appropriately define the concept of the term in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is.

According to the present invention, by supporting a mixture of platinum and rhenium on a porous carrier, the dehydrogenation activity is significantly improved even at low temperatures, making it possible to effectively obtain hydrogen from a liquid organic hydrogen storage body.

Figure 1 is a graph showing the degree of dehydrogenation of catalysts for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 of the present invention.
Figure 2 is a graph showing the degree of dehydrogenation of catalysts for hydrogen production prepared according to Examples 5 to 8 and Comparative Examples 3 to 5 of the present invention.
Figure 3 is a graph showing the degree of dehydrogenation of catalysts for hydrogen production prepared according to Examples 3, 9, 10, Comparative Examples 1, 6, and 7 of the present invention.
Figure 4 shows the results of 455 nm Raman spectroscopy analysis of catalysts for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 of the present invention.
Figure 5 shows spherical aberration-corrected scanning transmission electron microscopy (Cs corredcted STEM) images of catalysts for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 of the present invention.
Figure 6 shows line profiling of platinum and rhenium on catalyst particles in a mono- and double aberration-corrected transmission electron microscope (Dluble Cs & monochromated-TEM) image of the catalyst for hydrogen production prepared according to Example 3 of the present invention. ) shows the results.
Figure 7 shows Pt 4d XPS data of catalysts for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 of the present invention.
Figure 8 shows Re 4f XPS data of catalysts for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 of the present invention.
Figure 9 shows the Pt L ₃ -edge XANES spectrum of the catalyst for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 of the present invention.
Figure 10 shows the Re L ₃ -edge XANES spectrum of the catalyst for hydrogen production prepared according to Examples 1 to 4 and Comparative Example 2 of the present invention.
Figure 11 is a graph showing the results of comparing the dehydrogenation degree of the catalyst for hydrogen production prepared according to Example 6 of the present invention and a conventionally reported catalyst.

Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. In general, the nomenclature used herein is well known and commonly used in the art.

The present invention seeks to provide a catalyst for producing hydrogen with improved dehydrogenation activity even at low temperatures by additionally introducing rhenium as a co-catalyst to a catalyst carrying platinum, a method for producing the same, and a method for producing hydrogen using the same.

To this end, the present invention first provides a porous carrier; Platinum supported in the pores of the porous carrier; and rhenium mixed with the platinum and supported in the pores.

At this time, the porous carrier is a porous member with a large number of pores on the surface, and accommodates platinum and rhenium. Pore may be formed in the size of micropore or mesopore. In general, micropores are defined as 2 nm or less, and mesopores are defined as having a size of more than 2 nm but less than 50 nm. However, in the present invention, this is not necessarily limited, and any size that allows a mixture of platinum and rhenium to be supported is sufficient.

In addition, the porous carrier is preferably activated carbon or aluminum oxide (Al ₂ O ₃ ), and the activated carbon may be selected from the group consisting of graphene oxide, carbon black, and Vulcan. In addition, the aluminum oxide preferably has θ-, δ-, γ-, and α- phases, and more preferably has a γ-phase.

In addition, as can be seen from the results of the following examples, it is preferable that the platinum and the rhenium are supported at a weight ratio of 1:0.1-1. As can be seen from the results of the following examples, if the weight ratio of the supported platinum and rhenium is outside the above range, the activity of the catalyst according to the present invention may decrease. In addition, when the platinum and the rhenium are mixed in the above weight ratio range and supported on a porous carrier, the dehydrogenation activity is significantly improved even at low temperatures due to the interaction between the platinum and rhenium, so it can be usefully used in hydrogen production. .

In addition, the platinum-rhenium is preferably supported in an amount of 1 to 10% by weight based on the total weight of the porous carrier.

Hereinafter, a method for producing a catalyst for hydrogen production according to the invention will be described. Here, the details regarding the catalyst for hydrogen production have been described above, and the description of overlapping matters will be omitted or only briefly described.

The method for producing a catalyst for hydrogen production according to the present invention includes the steps of (a) supporting a platinum precursor solution and a rhenium precursor solution in the pores of a porous carrier; and (b) reducing the porous carrier on which the platinum precursor solution and the rhenium precursor solution are supported.

To prepare the catalyst for hydrogen production according to the present invention, first (a) a platinum precursor solution and a rhenium precursor solution are supported in the pores of a porous carrier. At this time, it may be desirable to use a porous carrier dried at a temperature of 100 to 150° C. in order to remove water molecules remaining in the pores and increase the efficiency of supporting platinum and rhenium inside the pores of the carrier. In addition, when supporting the platinum precursor solution and the rhenium precursor solution, the platinum precursor solution and the rhenium precursor solution are mixed and supported simultaneously, the rhenium precursor solution is supported and then the platinum precursor solution is supported, or the platinum precursor solution is supported and then the rhenium precursor solution is supported. It can hold a solution.

To this end, step (a) includes supporting a mixed solution of a platinum precursor solution and a rhenium precursor solution in the pores of the porous carrier; Drying the porous carrier on which the mixed solution is supported; and calcining the dried porous carrier. At this time, the drying is preferably performed at a temperature range of 100 to 150°C for 8 to 24 hours, and the firing is preferably performed at a temperature range of 200 to 400°C for 30 minutes to 3 hours.

In addition, step (a) includes supporting a platinum precursor solution in the pores of the porous carrier; Drying the porous carrier on which the platinum precursor solution is supported; baking the dried porous carrier; and supporting a rhenium precursor solution in the pores of the calcined porous carrier. At this time, the drying is preferably performed at a temperature range of 100 to 150°C for 8 to 24 hours, and the firing is preferably performed at a temperature range of 200 to 400°C for 30 minutes to 3 hours.

In addition, step (a) includes supporting a rhenium precursor solution in the pores of the porous carrier; Drying the porous carrier on which the rhenium precursor solution is supported; baking the dried porous carrier; and supporting a platinum precursor solution in the pores of the calcined porous carrier. At this time, the drying is preferably performed for 8 to 24 hours at a temperature range of 100 to 150°C, and the firing is preferably performed for 30 minutes to 3 hours at a temperature range from 200 to 400°C.

In addition, platinum and rhenium supported on the porous carrier through step (a) are preferably supported at a weight ratio of 1:0.1-1. In addition, the sum of the platinum and rhenium supported is preferably 1 to 10% by weight based on the total weight of the porous carrier. As can be seen from the results of the following examples, if the weight ratio of the supported platinum and rhenium is outside the above range, the activity of the catalyst according to the present invention may decrease.

Additionally, step (a) may be performed by incipient wetness impregnation. In the case of support according to the initial wet support method, the support process may be repeated several times to ensure that the platinum precursor solution and the rhenium precursor solution are sufficiently supported, and a drying process may be performed for each support. Here, the porous carrier is preferably activated carbon or aluminum oxide (Al ₂ O ₃ ), and the activated carbon may be selected from the group consisting of graphene oxide, carbon black, and Vulcan. In addition, the aluminum oxide preferably has θ-, δ-, γ-, and α- phases, and may more preferably have a γ-phase. In addition, the platinum precursor solution refers to a platinum chloride group and a platinum nitrate salt, and is not particularly limited as long as it is a salt that can provide platinum, but is, for example, selected from the group consisting of platinum chloride, potassium hexachloroplatinate, chloroplatinic acid, and tetraammineplatinum nitrate. You can use anything that works. In addition, the rhenium precursor solution refers to the rhenium chloride group, rhenium hydroxide, and rhenium ammonium salt, and is not particularly limited as long as it is a salt that can provide rhenium, but is, for example, selected from the group consisting of perrhenic acid, ammonium perrhenatae, and rhenium chloride. can be used.

Next, in step (b), the porous carrier on which the platinum precursor solution and the rhenium precursor solution are supported is reduced using a mixed gas of hydrogen and nitrogen, specifically, H ₂ /N ₂ at a volume ratio of 5 to 20%. It is preferably carried out at 300 to 600°C for 30 minutes to 3 hours under a gas atmosphere. Through the above reduction step, the platinum-rhenium catalyst for hydrogen production according to the present invention is finally produced.

The present invention also includes the steps of mixing the catalyst for hydrogen production and a liquid organic hydrogen carrier (Liquid Organic Hydrogen Carrier, LOHC); and performing a dehydrogenation reaction after the mixing.

At this time, the liquid organic hydrogen storage is perhydro-Dibenzyltoluene, cyclohexane, methyl cyclohexane, decalin, benzyl toluene, and dibenzyltoluene. (dibenzyl toluene), perhydro-N-ethylcarbazole, and 2-[(N-methylcyclohexyl)methyl]piperidine, preferably perhydro- It may be dibenzyltoluene (perhydro-Dibenzyltoluene).

According to the present invention, the dehydrogenation reaction is preferably performed at a temperature of 250 to 300°C for 2 to 4 hours.

[Example]

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Example 1. After depositing platinum, rhenium supported 2Pt0 . 2Re / Al ₂ O ₃ Preparation of catalyst

(1) Preparation of platinum and rhenium precursor solution

A platinum precursor solution was prepared by mixing 0.399 ml of distilled water and 0.0397 g of tetraammineplatinum nitrate in a 5 ml vial and stirring for 10 minutes using an ultrasonic disperser. Then, 0.399 ml of distilled water and 1.606 ㎕ of perrhenic acid solution were mixed in a 5 ml vial and then ultrasonicated. A rhenium precursor solution was prepared by stirring for 10 minutes using a disperser.

(2) Production of γ-phase alumina

γ-phase alumina was prepared by calcining 1 to 20 g of boehmite (AlOOH) at 600°C for 4 hours in an air atmosphere.

(3) Production of γ-phase alumina loaded with platinum

The platinum precursor solution was supported on 1 g of the alumina using an initial wetness impregnation method. Afterwards, it was dried at 120°C for 12 hours and then heat treated at 300°C for 2 hours in an air atmosphere in a kiln.

(4) Preparation of 2Pt0.2Re/Al ₂ O ₃ catalyst with rhenium added as cocatalyst

The rhenium precursor solution was supported on the γ-phase alumina on which the platinum was supported using an initial wet deposition method. Afterwards, it was dried at 120°C for 12 hours and then reduced at 450°C for 1 hour under a 10% H ₂ /N ₂ gas atmosphere to produce a platinum-rhenium catalyst (2Pt0.2Re/Al ₂ O ₃ ) for hydrogen production according to the present invention. Manufactured. The catalyst was stored under vacuum atmosphere.

Example 2. 2Pt0.4Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst (2Pt0.4Re/Al ₂ O ₃ ) for hydrogen production according to the present invention was prepared using the same method as Example 1, except that 3.211 ㎕ of perrhenic acid solution was used.

Example 3. 2Pt0.8Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst (2Pt0.8Re/Al ₂ O ₃ ) for hydrogen production according to the present invention was prepared using the same method as Example 1, except that 6.422 ㎕ of perrhenic acid solution was used.

Example 4. 2Pt1.6Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst (2Pt1.6Re/Al ₂ O ₃ ) for hydrogen production according to the present invention was prepared using the same method as Example 1, except that 12.844 ㎕ of perrhenic acid solution was used.

Example 5. 4.8Pt0.5Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst for hydrogen production according to the present invention (4.8Pt0.5Re/Al ₂ O ₃ ) was prepared.

Example 6. 4.2Pt1.0Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst for hydrogen production according to the present invention (4.2Pt1.0Re/Al ₂ O ₃ ) was prepared.

Example 7. 3.6Pt1.8Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst for hydrogen production according to the present invention (3.6Pt1.8Re/Al ₂ O ₃ ) was prepared.

Example 8. 2.7Pt2.7Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

The platinum-rhenium catalyst for hydrogen production according to the present invention (2.7Pt2.7Re/Al ₂ O ₃ ) was prepared.

Example 9. co-2Pt0.8Re/Al carrying platinum and rhenium simultaneously ₂ O ₃ Preparation of catalyst

A platinum-rhenium precursor solution was prepared by mixing 0.399 ml of distilled water, 0.0510 g of chloroplatinic acid instead of tetraammineplatinum nitrate, and 6.422 ㎕ of perrhenic acid in a 5 ml vial and stirring for 10 minutes using an ultrasonic disperser.

The platinum-rhenium precursor solution was supported on 1 g of the alumina using an incipient wetness impregnation. After drying at 120°C for 12 hours, heat treatment at 300°C for 2 hours in an air atmosphere in a kiln, and then reduced at 450°C for 1 hour in a 10% H ₂ /N ₂ gas atmosphere to produce hydrogen according to the present invention. A platinum-rhenium catalyst (co-2Pt0.8Re/Al ₂ O ₃ ) was prepared.

Example 10. 0.8Re-cal-2Pt/Al loaded with rhenium and then loaded with platinum ₂ O ₃ Preparation of catalyst

By changing the process order of (3) and (4) of Example 1, rhenium-supported γ-phase alumina was manufactured, and then the tungsten precursor solution was supported by the initial wetting method. The same method as Example 1. A rhenium-platinum catalyst (0.8Re-cal-2Pt/Al ₂ O ₃ ) for hydrogen production was prepared by supporting rhenium and then supporting platinum.

Comparative example One. 2Pts / Al ₂ O ₃ Preparation of catalyst

A platinum catalyst (2Pt/Al ₂ O ₃ ) for hydrogen production without rhenium was prepared using the same method as Example 1, except that a rhenium precursor solution was not used.

Comparative Example 2. 2Pt3.2Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst (2Pt3.2Re/Al ₂ O ₃ ) for hydrogen production was prepared using the same method as in Example 1, except that 25.689 ㎕ of perrhenic acid solution was used.

Comparative Example 3. 5Pt/Al ₂ O ₃ Preparation of catalyst

A platinum catalyst (5Pt/Al ₂ O ₃ ) for hydrogen production without rhenium was prepared using the same method as Example 1, except that 0.0992 g of tetraammineplatinum nitrate was used, except that the rhenium precursor solution was not used.

Comparative Example 4. 1.8Pt3.4Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst (1.8Pt3.4Re/Al ₂ O ₃ ) for hydrogen production was prepared using the same method as in Example 1, except that 0.0341 g of tetraammineplatinum nitrate and 26.341 ㎕ of perrhenic acid solution were used. did.

Comparative Example 5. 1.4Pt3.8Re/Al loaded with platinum and then loaded with rhenium ₂ O ₃ Preparation of catalyst

A platinum-rhenium catalyst (1.4Pt3.8Re/Al ₂ O ₃ ) for hydrogen production was prepared using the same method as in Example 1, except that 0.0257 g of tetraammineplatinum nitrate and 29.750 ㎕ of perrhenic acid solution were used. did.

Comparative Example 6. 0.8Re-dry-2Pt/Al in which rhenium was deposited and then platinum was deposited, but no heat treatment process was performed when rhenium was deposited. ₂ O ₃ Preparation of catalyst

The same method as Example 1 was used except that 0.0397 g of tetraammineplatinum nitrate and 6.422 ㎕ of perrhenic acid solution were used, but the heat treatment process at 300°C for 2 hours in (3) of Example 1 was not performed. A rhenium-platinum catalyst (0.8Re-dry-2Pt/Al ₂ O ₃ ) for hydrogen production was prepared.

Comparative Example 7. 1Re/Al ₂ O ₃ Preparation of catalyst

A rhenium catalyst (1Re/Al ₂ O ₃ ) for hydrogen production without platinum was prepared using the same method as in Example 1, except that 8.028 ㎕ of a rhenium precursor solution perrhenic acid solution was used instead of a platinum precursor solution. Manufactured.

Experiment example 1. Measurement of dehydrogenation ability of catalyst according to the loading ratio of platinum and rhenium

(1) In order to confirm the catalyst performance according to the supporting ratio of platinum and rhenium, the dehydrogenation ability of the catalyst for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 was measured.

Specifically, 5 g of perhydro-dibenzyltoluene as a reactant was charged into a 100 ml 3-neck flask, and each of the catalysts according to Examples 1 to 4 and Comparative Examples 1 to 2 was added at a ratio of active metal to reactant of 0.10. It was filled to a % molar ratio. Inside the reaction equipment, a purging process was performed for 10 minutes using 100 sccm ultra-high purity nitrogen. To adjust the reaction temperature to 270°C, it was heated with stirring at 700 rpm for 30 minutes, and after reaching a steady state, it was maintained for 3 hours and 30 minutes to proceed with the dehydrogenation reaction. The amount of hydrogen generated during the dehydrogenation reaction was cooled to 25°C through two coolers and then recorded in real time using a mass flow meter. After completion of the reaction, the reactor was cooled to room temperature using a natural cooling method. The volume of hydrogen recorded by the mass flow meter was quantified in moles using the van der Waals equation, and the degree of dehydrogenation was calculated by comparing it to the total amount of hydrogen that can be produced by perhydro-dibenzyltoluene, and the results are shown in Figure 1 and Table below. It is shown in 1.

Pt wt.% Re wt.% Dehydrogenation degree (%) 2Pts 2.4 - 65.82 2Pt0.2Re 2.3 0.26 71.33 2Pt0.4Re 2.4 0.59 72.03 2Pt0.8Re 2.3 1.10 73.75 2Pt1.6Re 2.2 2.23 73.74 2Pt3.2Re 2.2 4.23 65.0

As shown in Table 1 and Figure 1 below, when platinum and rhenium are supported on a porous carrier at a weight ratio of 1:0.1 to 1:0.8 (Examples 1 to 4), rhenium is not supported (Comparative Example 1), it was confirmed that even when rhenium was supported, the dehydrogenation degree of the catalyst was significantly improved compared to when the content exceeded the above range (Comparative Example 2), and among them, Example 3, that is, when platinum and rhenium were supported at a weight ratio of 1:0.4 In this case, it was confirmed that the dehydrogenation degree of the catalyst was the best. Through the above results, the catalysts of Examples 1 to 4, in which platinum and rhenium were supported on a porous carrier at a weight ratio of 1:0.1 to 1:0.8 according to the present invention, can be usefully used as a catalyst for hydrogen production compared to other catalysts. It was confirmed that it was possible.

(2) Next, the weight of the supported metal was fixed at about 5 wt%, and in order to check the catalyst performance according to the supported ratio of platinum and rhenium, Examples 5 to 8 and Comparative Examples 3 to 5 were used. The dehydrogenation ability of the catalyst for hydrogen production prepared according to was measured.

Specifically, 5 g of perhydro-dibenzyltoluene as a reactant was charged into a 100 ml 3-neck flask, and each of the catalysts according to Examples 5 to 8 and Comparative Examples 3 to 5 was prepared at a ratio of active metal to reactant of 0.10. It was filled to a % molar ratio. The inside of the reaction equipment was purged using 100 sccm ultra-high purity nitrogen for 10 minutes. To adjust the reaction temperature to 270°C, it was heated with stirring at 700 rpm for 30 minutes, and after reaching a steady state, it was maintained for 3 hours and 30 minutes to proceed with the dehydrogenation reaction. The amount of hydrogen generated during the dehydrogenation reaction was cooled to 25°C through two coolers and then recorded in real time using a mass flow meter. After completion of the reaction, the reactor was cooled to room temperature using a natural cooling method. The volume of hydrogen recorded by the mass flow meter was quantified in moles using the van der Waals equation, and the degree of dehydrogenation was calculated by comparing it to the total amount of hydrogen that can be produced by perhydro-dibenzyltoluene. The results are shown in Figure 2 and the table below. It is shown in 2.

Pt wt.% Re wt.% Dehydrogenation degree (%) 5Pts 5.3 - 60.4 4.8Pt0.5Re 4.8 0.5 68.2 4.2Pt1.0Re 4.2 1.0 74.4 3.6Pt1.8Re 3.6 1.8 69.5 2.7Pt2.7Re 2.7 2.7 65.0 1.8Pt3.4Re 1.8 3.4 46.8 1.4Pt3.8Re 1.4 3.8 31.3

As shown in Table 2 and Figure 2 below, when platinum and rhenium are supported on a porous carrier at a weight ratio of about 1:0.1 to 1:1 (Examples 5 to 8), rhenium is not supported (compare Example 3), it was confirmed that even when rhenium was supported, the degree of dehydrogenation of the catalyst was significantly improved compared to when the content exceeded the above range (Comparative Examples 4 and 5), and among them, the degree of dehydrogenation of the catalyst according to Example 6 was the best. Confirmed. From the above results, the catalysts of Examples 5 to 8, in which platinum and rhenium were supported on a porous carrier at a weight ratio of about 1:0.1 to 1:1 according to the present invention, were more useful as catalysts for hydrogen production than other catalysts. It has been confirmed that this can be done.

Experiment example 2. Measurement of the dehydrogenation ability of the catalyst according to the loading order of platinum and rhenium and whether the calcination process is performed.

In order to confirm catalyst performance according to the loading order of platinum and rhenium and whether or not the sintering process was performed during loading, hydrogen production catalysts prepared according to Examples 3, 9, 10, Comparative Example 1, Comparative Example 6, and Comparative Example 7 were used. The dehydrogenation ability of the catalyst was measured. The measurement was conducted in the same manner as in Experimental Example 1, and the measurement results are shown in Table 3 and Figure 3 below.

Pt wt.% Re wt.% Dehydrogenation degree (%) 2Pts 2.4 - 65.82 co-2Pt0.8Re 2 0.8 66.96 0.8Re-cal-2Pt 2 0.8 72.90 0.8Re-dry-2Pt 2 0.8 22.13 2Pt-cal-0.8Re 2 0.8 73.75 1Re - One 1.82

As shown in Table 3 above and Figure 3 below, when platinum and rhenium were supported regardless of the loading order during catalyst preparation, the dehydrogenation ability was significantly improved compared to the catalyst supported only with platinum or rhenium. In the case of the catalyst that did not undergo the firing process (Comparative Example 6), it was confirmed that the dehydrogenation ability was significantly reduced compared to other catalysts.

Experiment example 3. Raman spectrum measurement

In order to confirm the phase of rhenium present on the surface of the synthesized platinum-rhenium catalyst, the 455 nm Raman spectrum of the catalyst for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 was measured. and the results are shown in Figure 4 below.

As shown in the results in Figure 4, the ν (Re=O) Peak was found to increase as the amount of rhenium increased, showing that the main species of rhenium present in the platinum _- rhenium catalyst was ReO Stretching ν (Re-O-Re) was constant in the peak area (400-800 cm ^-1 ), but was found to increase slightly in Examples 3 to 4 and Comparative Example 2, which is due to the formation of ReO _x clusters. It is judged to be caused by Considering that the dehydrogenation degree test results of Experimental Example 1 showed that the catalyst activity was improved starting from Examples 1 and 2 in which a small amount of rhenium was added, the catalyst activity improvement occurred even before the ReO _x cluster was formed. Therefore, it is believed that the formation _{of ReO}

Experiment example 4. STEM image measurements

In order to confirm the size of the metal and the positions of platinum and rhenium on the surface of the synthesized catalyst, the surface of the catalyst for hydrogen production prepared according to Examples 1 to 4 and Comparative Examples 1 to 2 was subjected to a scanning transmission electron microscope ( Images were taken using Scanning Transmission Electron Microscopy (STEM), and the results are shown in Figures 5 and 6 below.

As shown in Figure 5, the particles commonly observed in all catalysts were identified as platinum, and most were found to be similar in size. In addition, the ReOx monomer species, which was not observed in the catalyst of Comparative Example 1 in which rhenium was not added, was found to increase as the amount of rhenium added (Examples 1 to 4, Comparative Example 2), and the amount of rhenium added was the highest. In many of the catalysts of Comparative Example 2, _ReO In addition, through the results in Figure 6, it was confirmed that the catalyst of the present invention has a structure in which rhenium is wrapped around platinum particles between 1 and 2 nm.

Experiment example 5. XPS analyze

In order to confirm changes in the surface electronic structure of platinum and rhenium, (XPS) was measured, and the results are shown in Figures 7, 8, and Tables 4 and 5 below.

Binding Energy (eV) Pt ⁰ 4d _{5 /2} Pt ⁰ 4d _{3 /2} 2Pts 314.6 331.2 2Pt0.2Re 314.55 331.19 2Pt0.4Re 314.52 331.18 2Pt0.8Re 314.49 331.17 2Pt1.6Re 314.49 331.17 2Pt3.2Re 314.58 331.2

Binding Energy (eV) Re ⁺⁷ 4f _{7 /2} Re ⁺⁷ 4f _{5 /2} 2Pts - - 2Pt0.2Re 47.49 48.37 2Pt0.4Re 47.49 48.46 2Pt0.8Re 47.50 48.52 2Pt1.6Re 47.51 48.61 2Pt3.2Re 47.52 48.66

Through the results in Table 4 and Figure 7 below, the binding energy center value for Pt ⁰ 4d _{5 / 2} and Pt ⁰ 4d _{3 /2} gradually decreased from Comparative Example 1 to Examples 1 to 4 due to the addition of rhenium. As confirmed to increase in Comparative Example 2, it was confirmed that platinum became rich in electrons due to electron donating, causing a shift toward low binding energy, and then losing electrons again in Comparative Example 2 to shift to high binding energy. In addition, through the results in Table 5 and Figure 8 below, the binding energy center values for Re ^{+ 7} 4d _{7 / 2} and Re ^{+ 7} 4d _{5 /2} were determined by the addition of rhenium in Examples 1 to 4 and Comparative Example 2. As it was confirmed that it increased to , it was confirmed that electron donating occurred in rhenium and electrons were lost and shifted to high binding energy.

Through the above results, when rhenium is used as a co-catalyst according to the present invention, electron donation from rhenium to platinum appears, which makes the surface of platinum rich in electrons, increasing reactivity, and consequently increasing the activity of the catalyst. It was confirmed that there was improvement.

Experiment example 6. XANES analyze

Additionally , in order to confirm changes in the surface electronic structures _of platinum and _rhenium , Ray absorption fine structure (XAFS) was measured. The X-ray absorption near edge structure (XANES) region of the XAFS data was analyzed, and the results are shown in Figures 9 and 10 below.

9, as the amount of rhenium increases in Comparative Example 1 and Examples 1 to 4, the rising edge of Pt L ₃ -edge shifts toward low binding energy, and toward high binding energy in Comparative Example 2. As it was confirmed that a shift occurred, it was confirmed that platinum gains electrons and becomes electronically rich, in the same manner as the XPS results. Through Figure 10, the amount of rhenium in Examples 1 to 4 and Comparative Example 2 As this increases, the rising edge of Re L ₃ -edge was confirmed to shift in the direction of high binding energy, and it was confirmed that electrons were moving from rhenium to platinum, similar to the XPS results.

Therefore, through the above results, the same as the results of Experimental Example 5, when rhenium is used as a cocatalyst according to the present invention, electron donation from rhenium to platinum appears, and this causes the electron-rich state of the platinum surface to become reactive. It was confirmed that this increases, and as a result, the activity of the catalyst is improved.

Experiment example 7. Comparison of dehydrogenation degree with conventional catalyst

In order to compare performance with the previously reported catalyst, the dehydrogenation ability of the hydrogen production catalyst prepared according to Example 6 and the previously reported catalyst were measured. The measurement was conducted in the same manner as in Experimental Example 1, and the measurement results are shown in Table 6 and Figure 11 below.

catalyst Dehydrogenation degree (%) 4.2Pt1.0Re/Al ₂ O ₃ 74.4 Pt/Al ₂ O ₃ (5 wt.%) ^[1] 44 Pt/Al ₂ O ₃ (5 wt.%) ^[2] 40 Pt/Al ₂ O ₃ (0.5 wt.%) 51 Pt/Al ₂ O ₃ (2.5 wt.%) 57 Pt/C (5 wt.%) ^[2] 55 Pt/C (5 wt.%) 57 Pt/SiO ₂ (5 wt.%) 52 Pd/Al ₂ O ₃ (0.5 wt.%) 8 Pd/C (5 wt.%) 16

[1] L. Shi et al., International Journal of Hydrogen Energy , 44(11) (2019) 5345; Reaction conditions: 0.03 mol LOHC, 0.3 mol.% catalyst (Metal/Reactant ratio), 3.5h., [2] N. Bruckner et al., ChemSusChem , 7 (2014) 229; Reaction conditions: 0.1 mol LOHC, 0.15 mol.% catalyst (Metal/Reactant ratio), 3.5h.

As shown in Table 6 and Figure 11 below, in the case of the catalyst (Example 6) in which platinum and rhenium were supported on an alumina carrier at a weight ratio of 4.2:1 according to the present invention, the degree of dehydrogenation was significantly higher than that of previously reported catalysts. It was confirmed that the catalyst according to the present invention was significantly improved, and it was confirmed that the catalyst according to the present invention can be usefully used as a catalyst for hydrogen production.

As the specific parts of the present invention have been described in detail above, it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. something to do. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (14)

As a catalyst for liquid organic hydrogen carrier (LOHC) dehydrogenation,
porous carrier; Platinum supported in the pores of the porous carrier; And rhenium mixed with the platinum and supported in the pores,
The platinum and the rhenium are supported at a weight ratio of 1:0.1-0.8,
A catalyst for dehydrogenation of a liquid organic hydrogen storage, characterized in that the liquid organic hydrogen storage is perhydro-Dibenzyltoluene. According to paragraph 1,
A catalyst for dehydrogenation of liquid organic hydrogen storage, characterized in that the porous carrier is activated carbon or aluminum oxide (Al ₂ O ₃ ). According to paragraph 2,
A catalyst for dehydrogenation of liquid organic hydrogen storage, characterized in that the activated carbon is selected from the group consisting of graphene oxide, carbon black, and Vulcan. delete A method for producing a catalyst for dehydrogenation of the liquid organic hydrogen reservoir of claim 1, comprising:
(a) supporting a platinum precursor solution and a rhenium precursor solution in the pores of a porous carrier; and
(b) reducing the porous carrier on which the platinum precursor solution and the rhenium precursor solution are supported,
A method for producing a catalyst for dehydrogenation of liquid organic hydrogen storage, characterized in that platinum and rhenium are supported at a weight ratio of 1:0.1-1. According to clause 5,
Step (a) includes supporting a mixed solution of a platinum precursor solution and a rhenium precursor solution in the pores of the porous carrier; Drying the porous carrier on which the mixed solution is supported; and calcining the dried porous carrier. According to clause 5,
Step (a) includes supporting a platinum precursor solution in the pores of the porous carrier; Drying the porous carrier on which the platinum precursor solution is supported; baking the dried porous carrier; and supporting a rhenium precursor solution in the pores of the calcined porous carrier. According to clause 5,
Step (a) includes supporting a rhenium precursor solution in the pores of the porous carrier; Drying the porous carrier on which the rhenium precursor solution is supported; baking the dried porous carrier; and supporting a platinum precursor solution in the pores of the calcined porous carrier. delete According to clause 5,
A method for producing a catalyst for dehydrogenation of liquid organic hydrogen storage, characterized in that step (a) is performed by incipient wetness impregnation. According to clause 6,
A method for producing a catalyst for dehydrogenation of liquid organic hydrogen storage, characterized in that the reduction in step (b) is performed at 300 to 600 ° C. in a mixed gas atmosphere of hydrogen and nitrogen. Mixing the catalyst according to claim 1 and a liquid organic hydrogen carrier (LOHC); and
A method for producing hydrogen comprising performing a dehydrogenation reaction after mixing. According to clause 12,
A method for producing hydrogen, wherein the liquid organic hydrogen storage material is perhydro-Dibenzyltoluene. According to clause 12,
A method for producing hydrogen, characterized in that the dehydrogenation reaction is performed for 2 to 4 hours at a temperature of 250 to 300 ° C.