KR20160027370A

KR20160027370A - Unsupported hydrolysis-catalyst and it's manufacturing method

Info

Publication number: KR20160027370A
Application number: KR1020140113750A
Authority: KR
Inventors: 박권필; 나일채
Original assignee: 주식회사 씨엔엘에너지
Priority date: 2014-08-29
Filing date: 2014-08-29
Publication date: 2016-03-10

Abstract

The present invention relates to a hydrolysis catalyst used in a reaction for generating hydrogen by hydrolysis of a hydrogen compound. The hydrolysis catalyst has a problem of high loss and time-consuming process in the process of supporting a catalyst on a support, . The present invention by mixing the aqueous solution with stirring to precipitate CoCl ₂ aqueous solution to separate the layers, and the non-supported Co-B catalyst prepared by firing dried after washing, and NaH ₂ PO ₂ and CoCl ₂ aqueous solution of NaBH ₄ Co- P aqueous solution to prepare a non-supported Co-PB catalyst prepared by stirring the aqueous NaBH ₄ solution and the aqueous solution of Co-P to precipitate the separated layer, washing, drying and firing the same, .

Description

Unsupported hydrolysis catalyst, it's manufacturing method and use method,

More particularly, the present invention relates to a non-supported hydrolysis catalyst which is provided as a non-supported catalyst as a catalyst for hydrolysis of NaBH ₄ and is effective in a continuous reactor, And a method of using the same.

Fuel cells that use hydrogen as an alternative energy source in the future are currently being studied because of their high energy efficiency and environmental friendliness. PEMFC (PEMFC) is the most suitable portable fuel cell that uses hydrogen as a fuel among fuel cell types. It is difficult to store and supply hydrogen as a fuel.

There are many ways to store and supply hydrogen, but in many ways chemical hydrides are the most likely method. Chemical hydrides include CaH ₂ , MgH ₂ , C ₁₀ H ₁₈ , NH ₃ BH ₃ , and NaBH ₄ . Of these, NH ₃ BH ₃ (Amoniaborane, AB) has recently been attracting much attention due to its high hydrogen storage capacity of 19.6 wt%, but a high hydrogen release temperature (above 100 ° C.) and reaction byproducts (borazine, ammonia, diborane) Which causes the performance degradation. Due to the additional device to prevent this, the hydrogen generating system has a low hydrogen storage capacity.

Chemical hydrides consider a wide variety of conditions, including safety, non-flammability, non-toxicity, high hydrogen storage capacity, and the reaction products should not affect the PEMFC. As a hydrogen source for mobile fuel cells, NaBH ₄ is being studied and developed as a chemical hydride satisfying severe conditions. NaBH ₄ has a high hydrogen storage capacity of 10.6 wt% and the reaction product borax is environmentally friendly and can be reproduced as a reactant.

Since the rate of hydrolysis of NaBH ₄ is slow, use a catalyst to improve the rate of hydrogen generation and add NaOH for stability during storage of NaBH ₄ . The hydrolysis reaction formula is as shown in Equation (1).

(1)

The catalysts used in the formula (1) were initially developed with noble metal catalysts such as Pt, Pd and Ru, but were not suitable for practical use because they were noble metals. The transition metal such as Mg, Ni, Co is inexpensive and the catalytic activity for the NaBH ₄ hydrolysis reaction and the catalyst production method are also studied because of the advantages that are easy because they use the chemical reduction method.

When hydrolysis is carried out with these catalysts, 2 mol of H ₂ O does not react with 1 mol of NaBH ₄ as shown in equation (1) but actually 4 to 10 mol of H ₂ O reacts to generate NaBO ₂ hydrate The hydrogen storage capacity is reduced. NaBH ₄ When 1 mol is reacted with 4 mol of H ₂ O, the hydrogen storage capacity becomes 7.3 wt%, and when it reacts with 10 mol, it decreases to 3.7 wt%. Therefore, it is necessary to increase the NaBH ₄ concentration in the aqueous solution to increase the hydrogen storage capacity.

Many of the above-mentioned various NaBH ₄ hydrolysis catalysts were tested in an aqueous solution of NaBH _{4 in an} amount of less than 10 wt% and used in powder form. However, in the present invention, a high concentration of 20 to 25 wt% Respectively.

Further, in controlling the temperature and the reaction by-product recovery problem in a batch reactor because the need to use a continuous flow reactor to fix the catalyst to the support decompose the NaBH ₄ singer.

However, there is a problem in that the cost of the catalyst for the hydrolysis reaction of NaBH ₄ is increased and the economical efficiency is decreased because the catalyst is loaded with a large amount of time in the process of supporting the catalyst on the support.

Korean Patent Laid-Open No. 10-2011-006050 (June 08, 2011)

In order to solve the problem that the cost of the catalyst for the hydrolysis reaction of NaBH ₄ is increased due to a large loss and time in the process of supporting the catalyst on the support, A non-supported hydrolysis catalyst which can be effectively used in a continuous reactor by producing an unsupported catalyst, and a method for producing and using the catalyst.

Non-supported Co-B and Co-PB catalysts are provided as hydrolysis catalysts for non-supported NaBH _{4 according} to the present invention.

The process for preparing the catalyst according to the present invention is as follows.

The Co-B catalyst,

A first step of preparing an aqueous solution of NaBH _{4 and} an aqueous solution of CoCl ₂ at a molar ratio of 5: 2: 1;

A second step in which the NaBH ₄ aqueous solution is slowly added to an aqueous solution of CoCl ₂ and stirred to react;

Adding the NaBH ₄ aqueous solution, stirring, and allowing the mixture to stand to form a precipitate layer;

The precipitated layer is vacuum filtered, washed with distilled water, pulverized, and then dried at room temperature.

The Co-P-B catalyst,

An eleventh step of preparing an aqueous solution of Co-P by mixing NaH ₂ PO ₂ aqueous solution and CoCl ₂ aqueous solution at a molar ratio of 2 to 0.5: 1;

(B) preparing NaBH ₄ aqueous solution and Co-P aqueous solution at a molar ratio of 5: 2: 1;

The NaBH ₄ aqueous solution is slowly added to the aqueous solution of Co-P to stir and react;

The Co-B catalyst and the Co-PB catalyst are prepared by the above-mentioned method and then calcined at 200 to 400 ° C for 2 to 4 hours in an N ₂ atmosphere.

As the method of using the non-supported hydrolysis catalyst,

A certain amount of the non-supported catalysts prepared by the above-described method is used in a bag to fix the inside of the hydrogen generating reactor. A hydrophilic surface, synthetic fiber, or Ni mesh is used as the sealing material so that the NaBH ₄ aqueous solution penetrates well into the bag and the by-product aqueous solution can be discharged well out of the bag.

Put 1/2 to 1/5 of the catalyst particles in the sealing space and sew the rim by stitching or the like so that the catalyst particles do not come out. When the catalyst comes into contact with oxygen and moisture in the air, its activity decreases due to oxidation reaction or the like. Therefore, the catalyst bag is put into a plastic bag and nitrogen purge is performed to remove oxygen and moisture, and then the plastic bag is sealed with an adhesive or the like.

Before the catalytic reaction, the plastic bag is opened and the catalyst bag is put into the reactor so that it can be used.

NaBH _{4 according} to the present invention In the hydrolysis catalytic process, the amount of raw material reagent was reduced to about 1/400 compared with the conventional method, the production method was simple, and the manufacturing process time was shortened, thereby improving the economical efficiency. It is also possible to generate hydrogen using a high concentration NaBH ₄ solution, and the yield of hydrogen generation is not reduced compared with the conventional catalyst, and the catalyst loss rate is also smaller than that of the conventional catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a process flow diagram of a non-supported Co-B production process according to the present invention.
Fig. 2 is a process for manufacturing a non-supported Co-PB according to the present invention. Fig.
3 is a SEM photograph drawing,
(a) Co-B, (b) Co-B magnification, (c) Co-PB, and (d) Co-PB magnification.
FIG. 4 is an illustration of yield and hydrogen evolution rates for 20% NaBH ₄ , Co-B catalysts.
Figure 5 is an illustration of yield and hydrogen evolution rates for 20% NaBH ₄ , Co-PB catalyst.
FIG. 6 is an illustration of a yield and hydrogen evolution rate for a 25% NaBH ₄ , Co-B catalyst.
Figure 7 is an illustration of yield and rate of hydrogen evolution in a 25% NaBH ₄ , Co-PB catalyst.
8 is NaBH ₄ An example of catalyst loss rate at each concentration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As the hydrolysis catalyst of the non-supported NaBH _{4 according} to the present invention, there is provided a non-supported Co-B or Co-PB catalyst. The process for preparing the catalyst according to the present invention is as follows.

1 is a view showing a non-supported Co-B manufacturing process according to the present invention. As shown therein,

(S1) for preparing an aqueous solution of NaBH _{4 and} an aqueous solution of CoCl ₂ at a molar ratio of 5 to 2: 1, and a second step (S2) for stirring and reacting the NaBH ₄ aqueous solution slowly with the aqueous solution of CoCl ₂ , ), and a fourth step of the NaBH ₄ aqueous solution and the step 3 (S3) both with stirring and after adding the value of the phase separation when the sediment has been formed, the sediment vacuum filtration, washing using distilled water and pulverized, and then room temperature drying (S4) to produce a Co-B catalyst.

The present invention also provides a fifth step (S5) of producing the Co-B catalyst by the method of the first to fourth steps (S1 to S4) and then calcining at 200 to 400 ° C for 2 to 4 hours in an N ₂ atmosphere .

2 is a view showing a process for producing a non-supported Co-P-B catalyst according to the present invention. As shown therein,

NaH ₂ PO ₂ solution and CoCl 2 - 0.5 ₂ aqueous solution in a molar ratio: 5, the second step 11 are mixed to be the first to make the Co-P solution (S11) with the aqueous solution and Co-P solution of the NaBH ₄ in a molar ratio ~ 2:01 stirring be added both to each manufacturing step 12 (S12), and the NaBH steps of claim 13 for agitating in response while applying a _fourth aqueous solution gradually to the Co-P solution (S13) with, the NaBH ₄ solution, which is (S14) of separating the precipitate layer when the precipitate layer is formed, and a step (S15) of washing the precipitated layer with distilled water after vacuum filtration, followed by pulverization and drying at room temperature, PB catalyst.

The method further includes a step S16 of producing the Co-PB catalyst by the manufacturing method of the eleventh to fifteenth steps (S11 to S15) and then firing at 200 to 400 ° C for 2 to 4 hours in an N ₂ atmosphere .

Meanwhile, a method of using the non-supported catalysts prepared by the above-mentioned production method is used by putting a certain amount into a catalyst bag for fixing in the hydrogen generation reactor.

In the catalytic bag, a hydrophilic surface, synthetic fiber, or Ni mesh is used as the sealing material so that the NaBH ₄ aqueous solution penetrates well into the bag and the by-product aqueous solution can be discharged well out of the bag.

The catalyst particle size is made 0.7 to 1.2 .mu.m, and the size of the pores is 0.5 to 1.02 .mu.m so that the aqueous solution passes but the catalyst does not escape.

Put 1/2 to 1/5 of the catalyst particles in the sealing space and sew the rim by stitching or the like so that the catalyst particles do not come out.

Also, when the catalyst comes into contact with oxygen and moisture in the air, its activity decreases due to oxidation reaction or the like. Therefore, the catalyst bag is put into a plastic bag, and nitrogen purge is performed to remove oxygen and moisture. Then, the plastic bag is sealed with an adhesive or the like.

Example 1)

In the same manner as the constitution of the invention, the catalyst was prepared as follows.

The Co-B catalyst,

An aqueous solution of NaBH _{4 and} an aqueous solution of CoCl _{2 were} prepared in a molar ratio of 3: 1, and the NaBH ₄ aqueous solution was gradually added to the aqueous solution of CoCl ₂ to react. After the NaBH ₄ aqueous solution is added, the mixture is further stirred for about 10 minutes and left to stand. Leave for about 30 minutes to separate the layers once they are formed. The precipitate layer is vacuum filtered, washed with distilled water, pulverized and then dried at room temperature.

The Co-P-B catalyst,

Creating a Co-P solution were mixed to be a 1, 3 of an aqueous solution and Co-P aqueous solution of NaBH ₄ in a molar ratio:: NaH ₂ PO ₂ solution and CoCl 1 to ₂ aqueous solution in a molar ratio producing be 1 and the NaBH ₄ solution slowly Co-P aqueous solution while stirring. The production method is the same as that of the Co-b catalyst production method.

The Co-B catalyst and the Co-PB catalyst were prepared by the above method and then calcined at 300 ° C for 3 hours in an N ₂ atmosphere.

The Co-B / FeCrAlloy catalyst,

An FeCrAlloy alloy having a size of 1.0 X 3 cm to 2.0 X 5 cm and an aqueous solution of 1.0 mol of CoCl ₂ .6H ₂ O and an aqueous solution of NaBH ₄ 3mol aqueous solution was injected alternately at intervals of 10 seconds, followed by washing with distilled water. These catalysts were BET analyzed and the results are summarized in the table below.

The Co-P-B / FeCrAlloy catalyst,

An FeCrAlloy alloy of the same size was immersed in an aqueous solution of 1 mol of CoCl ₂ · 6H ₂ O and 1 mol of NaH ₂ PO ₂ · H ₂ O, and an aqueous solution of 3 mol of NaBH ₄ at intervals of 10 seconds, followed by washing with distilled water. These catalysts were BET analyzed and the results are summarized in the table below.

As a result of BET analysis of the catalyst Co-PB
unsupported Co-B
unsupported Co-PB
/ FeCrAlloy Co-B
/ FeCrAlloy BET (m ² / g) 10.35 75.70 22.31 4.08 Pore diameter (A) 160.97 108.46 57.89 576.48

As shown in the SEM photograph of FIG. 3, the Co-B catalyst having no supported Co-B catalyst may have a large BET area. However, as shown in (a) of FIG. The non-supported Co-PB had a relatively small BET area of 10.35 m ² / g, but the NaBH ₄ hydrolysis reaction proceeded at a very high rate at 60-100 ° C. 3 (a) is a 50.0 μm photograph of Co-B, and (b) is an enlarged view of 1.00 μm of Co-B. (c) is a 50.0um photographic view of Co-PB, and (d) is a 1.00um magnified view of Co-PB.

Example 2)

In the batch reactor, the NaBH ₄ concentration was adjusted to 40% (by weight) and NaOH was adjusted to 1.0% (weight), and then the Co-B catalyst prepared in Example 1 was placed in the fiber bag to carry out the hydrolysis reaction. The reactor was heat exchanged to a temperature of 80 to 90 ° C and the amount of generated hydrogen was measured by a mass flow meter (MFM).

The hydrogen generation rate is the same as the yield rate and hydrogen generation rate in NaBH ₄ 20% Co-B catalyst of FIG. As shown in FIG. 4, the hydrogen yield was measured to be about 0.6 L / min until 18 minutes and the cumulative hydrogen volume was measured until all the NaBH ₄ was consumed. As a result, a high yield of 98.4% was obtained.

Example 3)

In the batch reactor, NaBH ₄ concentration of 40% (weight) and NaOH 1.0% (weight) were carried out. Then, the Co-PB catalyst prepared in Example 1) was added to 20 g of the fiber bag for hydrolysis. Heat exchange was performed so that the temperature of the reactor was 80 to 90 ° C, and the amount of generated hydrogen was measured by a mass flow meter (MFM).

The hydrogen generation rate is the same as the yield rate and the hydrogen generation rate in NaBH ₄ 20%, Co-PB catalyst of FIG. 5. As shown in FIG. 5, the hydrogen yield was measured to be about 0.8 L / min until 10 minutes and the cumulative hydrogen volume was measured until all the NaBH ₄ was consumed. As a result, a high yield of 98.5% was obtained.

Example 4)

In the batch reactor, the NaBH ₄ concentration was adjusted to 45% (weight) and the NaOH was adjusted to 1.0% (weight), and then the Co-B catalyst prepared in Example 1) was added to the fiber bag to carry out the hydrolysis reaction.

Heat exchange was performed so that the temperature of the reactor was 80 to 90 ° C, and the amount of generated hydrogen was measured by a mass flow meter (MFM).

The hydrogen generation rate is the same as the yield rate and the hydrogen generation rate in NaBH ₄ 25% Co-B catalyst of FIG. 6. But as shown in FIG. 6, it tends to decrease rather than being constant. This is because the reaction increases the viscosity by the produced by-products, making contact with the catalyst and NaBH ₄ difficult. The hydrogen yield was calculated by measuring the cumulative hydrogen volume until all the NaBH ₄ was consumed. The hydrogen yield was 97.0%, which was lower than the 20% yield of NaBH ₄ but higher than the supported catalyst.

Example 5)

NaBH ₄ concentration of 45% (by weight) was added to the batch reactor to make NaOH 1.0% (weight), and then the Co-PB catalyst prepared in Example 1) was added to 20 g of the fiber bag for hydrolysis. Heat exchange was performed so that the temperature of the reactor was 80 to 90 ° C, and the amount of generated hydrogen was measured by a mass flow meter (MFM).

The hydrogen generation rate is the same as the yield rate and the hydrogen generation rate in the NaBH ₄ 25% Co-PB catalyst of FIG.

But is not kept constant as shown in FIG. 7, but shows a tendency to decrease. This is also due to the fact that the viscosity increases due to the by-produced reaction and the contact between the catalyst and NaBH ₄ becomes difficult. The hydrogen yield was calculated by measuring the cumulative hydrogen volume until all of the NaBH ₄ was consumed. The hydrogen yield was 95.3%, which was lower than the yield of 20% NaBH ₄ .

Example 6)

The durability of the non-supported catalyst was measured and compared. The amount of catalyst remaining after hydrolysis of the 20-30% NaBH ₄ aqueous solution with the Co-B catalyst and the Co-PB catalyst was measured in the batch reactor.

8 is NaBH ₄ Fig. 5 is a graph showing the catalyst loss rate at each concentration. Fig. As shown in FIG. 8, as the NaBH ₄ concentration increases, the catalyst loss rate increases. The higher the concentration of NaBH ₄ , the higher the loss of catalyst due to the increase of by-product viscosity due to the lack of water.

When NaBH _{4 is} 20% and 25%, the Co-B catalyst loss is higher than that of Co-PB catalyst. The non-supported Co-B non-supported catalyst particle is small and the rate of exiting the catalyst bag is higher than that of the non-supported Co-PB catalyst. By-product viscosities were high at NaBH ₄ 30%, indicating that the particle size of the Co-B catalyst or Co-PB catalyst was not affected by the loss rate.

S1 to S5: Co-B manufacturing process
S11 to S16: Co-PB manufacturing process

Claims

A method for producing a hydrolytic catalyst for use in a reaction for generating hydrogen by hydrolyzing a hydrogen compound,
A first step of preparing an aqueous solution of NaBH _{4 and} an aqueous solution of CoCl ₂ at a molar ratio of 5: 2: 1;
A second step in which the NaBH ₄ aqueous solution is slowly added to an aqueous solution of CoCl ₂ and stirred to react;
Adding the NaBH ₄ aqueous solution, stirring, and allowing the mixture to stand to form a precipitate layer;
The precipitated layer was vacuum filtered, washed with distilled water, pulverized and then dried at room temperature.
Characterized in that a non-supported Co-B catalyst is prepared by the method as described above.

The method according to claim 1,
Wherein the Co-B catalyst is calcined at 200 to 400 ° C for 2 to 4 hours in an N ₂ atmosphere after the Co-B catalyst is prepared by the above-described production method.

A method for producing a hydrolytic catalyst for use in a reaction for generating hydrogen by hydrolyzing a hydrogen compound,
An eleventh step of preparing an aqueous solution of Co-P by mixing NaH ₂ PO ₂ aqueous solution and CoCl ₂ aqueous solution at a molar ratio of 2 to 0.5: 1;
(B) preparing NaBH ₄ aqueous solution and Co-P aqueous solution at a molar ratio of 5: 2: 1;
The NaBH ₄ aqueous solution is slowly added to the aqueous solution of Co-P to stir and react;
Adding the NaBH ₄ aqueous solution, stirring, and allowing the mixture to stand to form a precipitate layer;
The precipitated layer was vacuum filtered, washed with distilled water, pulverized, and then dried at room temperature.
Characterized in that a non-supported Co-PB catalyst is prepared.

The method of claim 3,
Wherein the Co-PB catalyst is calcined at 200 to 400 ° C for 2 to 4 hours in an N ₂ atmosphere after the Co-PB catalyst is prepared by the above-described production method.

A hydrolysis catalyst used in a reaction for generating hydrogen by hydrolyzing a hydrogen compound,
The non-supported hydrolysis catalyst according to claim 1, wherein the catalyst is a non-supported Co-B catalyst.

A hydrolysis catalyst used in a reaction for generating hydrogen by hydrolyzing a hydrogen compound,
The non-supported hydrolysis catalyst according to claim 3, wherein the catalyst is a non-supported Co-PB catalyst.

In the method of using the non-supported hydrolysis catalyst,
The non-supported hydrolysis catalyst prepared by the process of any one of claims 1 to 4 is used in a catalyst bag,
The catalyst pouch may be formed,
A hydrophilic surface, a synthetic fiber, or an Ni mesh is used so that the hydrolyzed aqueous solution can be well penetrated into the bag and the by-product aqueous solution can be well discharged out of the bag,
The catalyst bag was placed in a plastic bag, and nitrogen purge was performed to remove oxygen and moisture. Then, the plastic bag was sealed and stored,
A method for using a non-supported hydrolysis catalyst, characterized in that a plastic bag is blown off before a catalytic reaction and a catalyst bag is put into a reactor.