JPS61222901A - Porous material for hydrogen occlusion - Google Patents

Abstract

PURPOSE:To provide a porous material for hydrogen occlusion, composed of a hydrogen-occlusion alloy powder and a specific synthetic resin, having open- cell network structure with uniform pore-size distribution, having excellent gas-permeability and uniform thermal conductivity and the heat absorption and generation caused by the occlusion and release of hydrogen. CONSTITUTION:20-50wt% synthetic resin having a tensile modulus of <=1,000kg/cm<2> (e.g. PVA) is dissolved in hot water. A pore-forming material such as starch, soluble salt, etc., is added to the solution and mixed homogeneously, and then 80-50wt% hydrogen-occlusion alloy powder having particle diameter of 1-500mum (e.g. TiFe) is added and uniformly mixed to the solution. The obtained mixture is added with an aldehyde and an acid catalyst, poured into a frame having a definite shape and cured at 40-80 deg.C. A hydrogen- occluding porous material having an apparent density of 0.3-3.0g/cm<3>, a porosity of 50-90wt%, an average pore diameter of 1-500mum and containing interconnected macropore network can be produced by this process.

Description

[Detailed Description of the Invention] Hydrogen energy is a clean energy with few resource constraints and no risk of polluting the natural environment. It is also easy to store and can be used as thermal energy, chemical energy,
Direct power generation using fuel cells, etc.

In recent years, there has been a lot of interest in the development of technology for using it, as it has excellent properties such as a wide range of applications.

Among the recent developments in hydrogen utilization technology, especially water.

Elementary storage alloys have attracted attention as materials that not only transport and store hydrogen, but also have energy conversion functions.

For example, iflMg-Ni system, La-Ni system, T(-Fe-
Many alloys have been developed, including Mn@ and Mitsushmetal-Nt. The properties required of these hydrogen storage alloys vary somewhat depending on the purpose of use, but the following properties are generally required.

(1) It is easy to form i-character and has a large amount of hydrogen storage.

(2) It has a high hydrogen absorption and release rate and has an appropriate dissociation pressure.

(3) High thermal conductivity.

(4) Even when hydrogen is absorbed and released repeatedly, the alloy hardly becomes pulverized.

However, currently developed hydrogen storage alloys
A change in volume occurs when absorbing and desorbing hydrogen.

Repeated occlusion and release results in pulverization, which poses a major practical problem. That is, due to the pulverization phenomenon of the alloy,
Cracks occur due to localized load on the container, pipes and valves become clogged due to pulverized particles of the original alloy, thermal conduction
Various problems occur, such as lowering J and slowing down the rate of hydrogen adsorption and release, localized filling of the alloy, uneven heat generation and heat absorption, and uneven temperature. The current situation is a major obstacle to commercialization.

The present inventors completed the present invention as a result of intensive research to solve the above-mentioned problem 1.The purpose of the present invention is to solve the problems caused by the pulverization of hydrogen storage alloys and to solve the problems of hydrogen gas. The object of the present invention is to provide a hydrogen storage porous material that is capable of collecting, purifying, and efficiently utilizing hydrogen energy.

The hydrogen storage porous body of the present invention has a hydrogen storage alloy powder of 50 to 8
0% by weight, tensile modulus 1,000 N/cI! Consists of 20-5011% of the following synthetic resin, apparent density 0.3
~3.0#/CI&, porosity 50-85% by weight.

It is a porous body having continuous network macropores with an average pore diameter of 1 to 500 μm, and has a tensile modulus of elasticity of 1. The synthetic resin raw material of OOOkQ/d is obtained by mixing and reacting with a total pore forming material, a blowing agent, a curing catalyst, etc.

The hydrogen storage alloy powder used for manufacturing the hydrogen storage porous body of the present invention is not particularly limited, and examples include TiFe, TiFe, etc.
6. gMnO,1, TiMn1. s, Feoy94T
io, 5eZro, o+Nbo, o4, MmN i 4
．． 5 people i o, s, MmN i 4.1! IF e
Q, B5, LaNi5, MgzNi, TiMn14
．． OaNi 5%LaNi 4.7AJo,a,M
mN i 4.5 Mn o, s, MmN i t 5
Alo, s, Tioo 6.5 F e O,5,
T io oo, 5unJ3.5, MmNi 5. Furthermore, Lm (Lantern Rich Mitsushi Metal) -Ni
Alloys such as Lm-Mn type and Lm-Mn type can be used. These hydrogen storage alloys are mixed with synthetic resin raw materials in the form of powder, and to obtain a good mixing state, K is 1. The size of the alloy powder particles is usually in the range of 1 to 500 μm, more preferably 5 μm. ~100 μm, most preferably 10
~50 μm.

The synthetic resin used in the present invention has a tensile modulus of 1.000 #
/cd or less Synthetic resin 1 For example, poly(vinyl formal, polyvinyl benzal, etc.) or polyurethane resin. It can absorb stress, prevent fine particles from falling off, and maintain its shape as a hydrogen-absorbing porous body.

Polyvinyl acetal resin is obtained by mixing polyvinyl alcohol and an aldehyde as a crosslinking agent with an Ik acid catalyst and reacting it.Formaldehyde, acetaldehyde, butyraldehyde, benzaldehyde, etc. can be used as the crosslinking agent. In addition, as a catalyst, oxalic acid, formic acid, acetic acid, propionic acid, tgI acid,
lactic acid, maleic acid.

Organic acids such as malonic acid, vinyl acetic acid, and para-toluenesulfone-ugly benzenesulfonic acid are suitable.

A porous polyvinyl acetal body can be produced by mixing a pore-forming material such as starch or responsive salts when mixing these raw materials.

Polyurethane is obtained by mixing polyisocyanate and polyol together with a catalyst and reacting the mixture, and a porous polyurethane body is obtained by adding a blowing agent.

As the polyisocyanate, for example, tolylene diisocyanate (TI), diphenylmethane diisocyanate (MDI), or modified MDI can be used. Polyols include polyether compounds and polyester compounds. Polyether compounds are the addition polymerization of ethylene oxide or propylene oxide to polyhydric alcohols such as glycerin, sorbitol, trimethylpropane, and sucrose. Polyester compounds are , adipic acid, phthalic anhydride, dimer acid, and other polyhydric acids and polyhydric alcohols. As the catalyst used for the reaction between polyisocyanate and polyol, amine compounds such as triethylenediamine, NN-dimethylcyclohexylamine, and trimethylpiperazine, and organometallic compounds such as stannath octoate and dibutyltin laurate can be used. In addition, as a blowing agent, fluorocarbon
11. Methyl chloride, nitroalkane, etc. can be used,
Further, as an additive, a cell oven agent such as a silicone dispersant, a paraffin dispersant, or a dimethylpolysiloxane-polyoxyalkylene copolymer may be added.

In order to produce a hydrogen storage porous body from the hydrogen storage alloy powder and the above-mentioned synthetic resin raw material, the following procedure may be performed.

If the synthetic plum fat is poly and nil acecool.

Dissolve a specified amount of polyvinyl alcohol as a synthetic resin raw material in warm water, add pore-forming materials such as starch and soluble salts, and mix uniformly. After adjusting the viscosity of the mixed liquid so that the metal powder does not settle, dissolve the specified amount. Add the hydrogen storage alloy powder and mix evenly.

An aldehyde as a crosslinking agent and an acid catalyst may be added and a curing reaction may be carried out at a temperature of about 40 to 80° C. in a mold having a predetermined shape. In addition to polyvinyl alcohol, synthetic resin raw materials include phenol formaldehyde resin, melamine resin, etc. It is better to add a small amount of 15 pieces without impairing the properties of polyvinyl alcohol resin. If the synthetic resin raw material is polyurethane, water and water can be added. The liols, catalyst, and hydrogen storage alloy powder are thoroughly mixed, and then a surfactant is added to the dispersion.

A foaming agent and other additives are added and thoroughly mixed, and then polyisocyanate is added to the mixture and stirred and mixed uniformly. A hydrogen-absorbing porous body is obtained by casting the thus obtained mixed composition into a mold of a predetermined shape, causing reaction and foaming.

The composition of the hydrogen storage porous body of the present invention is that the hydrogen storage alloy powder is usually 50 to 80% by weight, preferably 55 to 75% by weight;
Most preferably 60-75 weight tensile modulus 1,00
0#/- or less synthetic resin is usually 20 to 50% by weight, preferably 25 to 45% by weight, and most preferably 25 to 40% by weight.

When the content of hydrogen-absorbing alloy powder is less than 50%, the hydrogen-absorbing capacity of the hydrogen-absorbing alloy decreases because the amount of alloy powder is small and the proportion of alloy powder buried in the inner layer of the porous resin matrix increases. decreases, which is undesirable, and
It is also undesirable for applications such as heat storage materials for heat pumps because it causes a decrease in the amount of heat absorbed and a decrease in thermal conductivity.

If the content of the hydrogen-absorbing alloy powder exceeds 80 hydrogen atoms, the proportion of the porous resin matrix is too small to absorb the internal stress that occurs when the alloy is pulverized by repeated hydrogen absorption and release. Cracks may occur in the hydrogen-absorbing porous body, and in extreme cases, this may lead to breakage, and furthermore, the pulverized alloy powder may fall off from the porous body, which is undesirable.

The synthetic resin used in the present invention is a synthetic resin with a tensile modulus of 1.000 phantom/c11 or less, such as polyvinyl acetal such as polyvinyl formal or polyvinyl benzal, or polyurethane. It is possible to absorb the internal stress caused by the pulverization of the hydrogen storage alloy, completely prevent the fine particles from falling off, and provide the hydrogen storage porous body with good shape retention. In addition, both polyvinyl acetal and polyurethane can be easily made into porous bodies having a network-like continuous air atmosphere.
It is most preferable because it has good retention of the alloy fine powder and because of compounding, there is little deterioration in the hydrogen storage alloy.

Moreover, the hydrogen storage porous body of the present invention usually has an apparent appearance! ! Jt
0.3-3. Of/cd, porosity 50-90% f, preferred, apparent 'alt 0.40-2.5 f/
d porosity 60-85%, most preferably apparent density go, so ~ 2.3f/cd porosity 65-150%, when the unit volume is above 9. If the amount is too small, the practicality as a hydrogen storage porous body is poor. Also, the apparent density is 3. Of/lxl' or if the porosity is too small, less than about 50%, the gas permeability in the hydrogen storage porous body will decrease and cracks will easily occur in the porous body, which will reduce the advantages of the porous body. I don't like it because it gets lost.

Comparing polyvinyl acetal and polyurethane, which are suitable as the synthetic resin of the present invention, it was found that polyvinyl acetal has superior gas permeability compared to polyurethane, and the reduction in hydrogen storage capacity due to the composite of hydrogen storage alloy powder is less likely to occur. Less is preferable.

Further, there are various types of polyurethane such as soft, semi-hard, and hard polyurethanes, and among these, soft polyurethane is preferred. Flexible polyurethane has a greater elongation than polyvinyl acetate, and therefore has the advantage of providing better shape retention.

Furthermore, the average pore diameter of the hydrogen storage porous material of the present invention is usually 1 to 5.
00 μm, preferably 10-300 μm, most preferably 15-300 μm.

Does the hydrogen-absorbing porous material obtained by the present invention have the longed-for shape retention? This problem can be solved by repeatedly absorbing and releasing hydrogen. In addition, the hydrogen storage porous material is a porous material containing continuous pores with a uniform pore size distribution, and has good gas permeability and uniform thermal conductivity. The hydrogen storage porous material of the present invention has such characteristics that heat absorption and heat absorption are uniform and local heat accumulation does not occur.

It can be used for hydrogen separation and purification, hydrogen storage, or as a heat storage material for heat pumps, exhaust heat utilization heating and cooling systems, hydrogen compressors, etc.

The present invention will be specifically explained below using Examples.

Example 1 Polyvinyl alcohol (·P, V A ) with polymerization 11700 and saponification ff 99%? After dispersing and dissolving in a predetermined amount of water and heating, an aqueous dispersion of potato starch having a predetermined particle size was added and mixed with stirring while heating to 65° C. or higher.

Add a predetermined amount of hydrogen-absorbing alloy powder caNi5 (Japan Heavy and Chemical Industry (recipe product, particle size: reed) 00mesh) to this mixed solution.
was added and thoroughly stirred and mixed, and further water for preparing liquid IAI was added to adjust the mixed liquid volume to 10 kg. The starch concentration in the mixture was 3.0% by weight.

After cooling the above mixture to below 40'C,
Maleic acid aqueous solution 70o1 and 37% by weight
Formalin 9001-Additionally, after further stirring, the inner diameter 2
The mold was poured into a 50 x 250 x 250 cod vinyl chloride resin mold, allowed to harden in a 60°C hot water bath for 48 hours, then taken out and washed in the shower for 48 hours. Furthermore, the sample was
After drying at °C for 24 hours, a hydrogen-absorbing porous body containing mesh-like continuous pores was obtained.The weight ji of the hydrogen-absorbing porous body was measured, and the amount of polyvinyl formal was determined by considering the amount of CaNi5 alloy powder mixed in advance. Calculated. After measuring the various physical properties of the hydrogen storage porous material obtained in this way, it was placed in a stainless steel container and
After holding the sample under a reduced pressure of Torr for 1 hour, an activation process was performed in a hydrogen gas atmosphere of 20 atm, and the hydrogen absorption amount of the sample was measured. After hydrogen absorption and release were repeated 50 times, the sample was taken out and observed for damage. The results are shown in Table 1.

As is clear from Table 11, 0aNis powder 50-80
A good hydrogen-absorbing porous material was obtained using a device with a heavy weight ratio Example 2 Polypropylene ether polyol 2001, triethylenediamine If, silicone dispersant L-520 (Nippon Unicar (egg product) 20 f 1 blowing agent Freon 11 (
After uniformly mixing 20 fI of Mitsui Chemicals (egg products) and 10 F of water, a predetermined amount of hydrogen storage alloy powder and LaN are added to the mixture.
i4. yAlo, a (Japan Heavy Chemical Industry (egg product 1 particle size, knee N-100 mesh)) was added and thoroughly stirred and mixed.

Furthermore, tolylene diisocyanate TDI-
80,220ft-additionally stirred and mixed, and this mixture t2
Cast into a stainless steel mold of 00x200x250m,
After reacting for 10 minutes and demolding, it was dried at 70'Q for 48 hours to obtain a hydrogen-absorbing porous body.9 The weight of the hydrogen-absorbing porous body was measured, and the LaNi4. Calculate the amount of polyurethane by considering the amount of yAlo and a alloy powder. Furthermore, in the same manner as in Example 1, various physical properties and hydrogen storage amount of the hydrogen storage porous body were measured, and whether hydrogen was stored or released? The entire state of the sample was observed after 50 repetitions. The results are shown in Table 2.

(hereinafter referred to as Serihaku)

Claims (3)

[Claims] (1) Hydrogen storage alloy powder 50-80% by weight, synthetic resin with tensile modulus of 1,000kg/cm^3 or less 20-50%
Consists of weight%, apparent density 0.3-3.0kg/cm^
3. Porosity 50-90% by weight, average pore diameter 1-500μ
A hydrogen storage porous material having continuous macropores in the form of a network of m. (2) The hydrogen storage porous body according to claim (1), wherein the synthetic resin is polyvinyl acetal or polyurethane. (3) The hydrogen-absorbing porous body according to claim (1), wherein the hydrogen-absorbing alloy powder has a particle size of 500 μm or less.