Hydrogen preparing apparatus

3 4

reforming means, comprising a porous substrate and a DETAILED DESCRIPTION OF THE

hydrogen separating film which is formed on a predeter- INVENTION

mined surface portion of the porous substrate and which Next> ^ present invention be described in more

selectively separates hydrogen. detail with reference to embodiments on the basis of the

In the above-mentioned hydrogen preparing apparatus, 5 attached drawings, but the scope of the present invention

the hydrogen separating means is preferably supported in an should not be limited to these embodiments,

overhung state in a container having an inlet for a hydro- mG 1 is a schematic view showing one embodiment of

carbon and/or a hydrocarbon containing an oxygen atom, an the hydrogen preparing apparatus of the present invention,

outlet for separated hydrogen and another outlet for a gas 10 Reference numeral 1 is a wholly cylindrical porous

from which hydrogen has been separated. In addition, the io subs(ratei and this substrate 1 is in the state of a monolithic

hydrogen preparing apparatus is suitably equipped with a structure m which a plurality of cylindrical through-holes 2

cushion means for absorbing the expansion of the hydrogen ^ formed ^ ±e poKS of the substrate h a steam reforming

separating means. catalyst of Cu or the like for the hydrocarbon is supported,

In the present invention, the reforming catalyst is sup- thereby forming reforming catalyst layers 3. The diameter of

ported in the pores of the porous substrate or on the 15 the pores in this substrate 1 is required to be suitably

honeycomb carrier, and therefore the surface area of the controlled in consideration of the catalytic area and the

catalyst per unit volume of the apparatus can be increased, porosity. On the inner surfaces of the cylindrical through

whereby the necessary volume of a reaction apparatus can holes 2, hydrogen separating films 4 of Pd or aPd—-Ag alloy

be nnnimized. Moreover, the porous substrate can be formed ^ formed. The hydrogen permeability of the hydrogen

into a monolithic structure having through-holes, and the 20 separating films 4 is inversely proportional to the thickness

hydrogen separating films can be formed on the inner 0f these films, and so the hydrogen separating films are

surfaces of the through-holes which extend through the preferably as thin as possible. Specifically, the thickness of

porous substrate, whereby the area of the hydrogen separat- these films is suitably in the range of 1 to 20 urn. The

ing films per unit area of the porous substrate can be hydrogen separating films 4 can be formed by a chemical

increased. The above-mentioned monolithic structure means 25 plating method or a gaseous phase method, but on the inner

an integral structure in which a plurality of the through-holes surfaces of the through-holes 2, fine pore layers having a

are provided through the porous substrate. In the present p0re diameter of 0.01 to 0.5 urn, preferably 0.05 to 0.2 urn

invention, even when the reforming catalyst is supported in are formed in compliance with the formation conditions of

the pores of the porous substrate, its porosity can be the hydrogen separating films.

maintained, and thus, needless to say, a gas can pass through 30 ^ porous substrate 1 is received in a container 5 to

the porous substrate. manufacture the hydrogen preparing apparatus.

In addition, in the hydrogen preparing apparatus of the Reference numeral 6 is an inlet for a material gas of

present invention, the porous substrate or the honeycomb methanol and steam, numeral 7 is an outlet for a permeated

carrier can be used, whereby the breakage of the catalyst by 35 hydrogen gas, and 8 is an outlet for an unpermeated gas.

vibration can be prevented. In consequence, the apparatus Furthermore, reference numerals 9 and 10 are flanges, which

can be mounted on a car or the like and can suitably be can be made of a dense material such as a ceramic or a metal,

combined with a fuel battery. In the case that the hydrogen End surfaces 11 of the cylindrical through-holes 2 on the

preparing apparatus is applied to the car, methanol or ethanol sjde of the inlet 6 for the material gas and end surfaces 12

is preferable as the hydrocarbon which is the fuel to be ^ of tne porous substrate 1 on the side of the outlet 7 for the

reformed, because this kind of hydrocarbon is suitable for permeated hydrogen gas are airtightly sealed with a sealant

storage and transport. In order to lower the reforming sucn as a glass or a brazing material,

temperature, methanol is preferable. Moreover, as the fuel ^ the hydrogen preparing apparatus, the material gas A of

battery, there can be used the phosphate type and the solid methanol and steam is introduced into the apparatus through

polymeric type fuel batteries, but the solid polymeric type 45 ^ gas Met 6 and ^ fed t0 me reformmg

fuel battery is more preferable, because its operation tern- catalyst layers 3 of the porous substrate 1 through the flange

perature is as low as 100° C. or less and it is small-sized and „ Qn ^ reformmg catalyst layers 3> a reaction gas com

lightweight. prising hydrogen, carbon monoxide and carbon dioxide is

BRIEF DESCRIPTION OF THE DRAWINGS generated by the above-mentioned reforming reaction. Of

50 the reaction gas produced on the reforming catalyst layers 3,

FIG. 1 is a schematic view showing one embodiment of a predetermined amount of a hydrogen gas alone permeates

a hydrogen preparing apparatus regarding the present mven- through foe hydrogen separating films 4 formed on the inner

tloxi- surfaces of the cylindrical through-holes 2 (a permeated

FIG. 2 is a schematic view showing another embodiment hydrogen gas B), whereby the hydrogen gas can be sepa

of the hydrogen preparing apparatus regarding the present 55 rated fr0m the reaction gas, and the hydrogen gas is then

invention. discharged from the apparatus through tne flange 10 and the

FIG. 3 is a schematic view showing still another embodi- outlet 7. Furthermore, of the mixed gas of the reaction gas

ment of the hydrogen preparing apparatus regarding the and an unreacted gas, an unpermeated gas C which has not

present invention. permeated through the hydrogen separating films 4 is dis

FIG. 4 is a schematic view showing a further embodiment 60 charged from the apparatus through the outlet 8 for the

of the hydrogen preparing apparatus regarding the present unpermeated gas.

invention. FIGS. 2, 3 and 4 are schematic views showing other

FIG. 5 is one example of a hydrogen preparation flow embodiments of the hydrogen preparing apparatus regarding

chart into which the hydrogen preparing apparatus of the the present invention.

present invention is incorporated. 65 The hydrogen preparing apparatus in FIG. 1 has the

FIG. 6 is a schematic view showing another example of structure in which the material gas A is introduced into the

a porous substrate. reforming catalyst layers 3 through the end surface of the 5 6

porous substrate 1, but in the hydrogen preparing apparatus and by decreasing distances a and b between the outer wall

shown in FIG. 2, the material gas A is introduced into the of the porous substrate 1 and the inner wall of the container

reforming catalyst layers 3 through the outer periphery of 5. The distances a and b are each preferably in the range of

the porous substrate 1. 0-1 t0 10 mm- In order to further heighten the diffusion

In FIG. 2, the porous substrate 1 has a wholly cylindrical 5 efficiency, the space between the outer wall of the porous

shape and is in the state of a monolithic structure in which sl*.strate 1 and «j£inner ^.ftne container 5 ^ be ffled

a plurality of the cylindrical through-holes 2 are formed, as wlth a ceranuc fiber or ^ llke

in the case of FIG. 1. In the pores of the substrate 1, a steam A. Jne prepanng apparatus shown f FIG. 3 is

reforming catalyst of Cu or the like for the hydrocarbon is ^erent from ^ aPP^tuses in FIGS. 1 and 2 in that a

supported, thereby forming reforming catalyst layers 3. io reforming catalyst is supported on the surface of a honey

zL . . , - comb earner 13 arranged on the upstream side of the porous

The container 5 is constituted of a container body IS and M^ 1 tQ fQm mfomyi catal t k 14 mstead of

a hd 16, and it has an inlet 6 for the material gas A, an outlet ortin ±e steam reforming catalyst m ^ pores of ^

7 for the separated hydrogen gas B and another outlet 8 for T Jj-*.- J _i ,« j.,

F v, porous substrate 1. In addition, end surfaces 15 of the porous

an unpermeated gas C. substrate 1 on the side of the outlet 6 for the material gas are

The container body 15 is cylindrical and has a bottom, an sealed witn a sealant) so mat ^ outlet 7 for me separated

upper opening, the inlet 6 for the material gas on its outer hydrogen gas and the outlet 8 for the unpermeated gas are

periphery, and the outlet 8 for the unpermeated gas. In arranged inversely to the case of FIG. 1.

addition the container body 15 has an outward lug 17 ^ me h ^ ^ shown ^ nG 3 me

around the outer peripheral edge of the opening. ^ gas A fa int0 the apparatus through me

On the other hand, the lid 16 has a lower opening, the outlet 6 for material gaS5 and further fed to the reforming

outlet 7 for the separated hydrogen gas B at its central catalyst layers 14 of the honeycomb carrier 13, in which a

position, and an outward lug 18 around the outer peripheral reaction gas comprising hydrogen, carbon monoxide and

edge of the opening. carbon dioxide is produced. The thus produced reaction gas

The flanges 9, 10 are made of a ceramic or a metal and 25 is ied to the porous substrate 1, and a hydrogen gas alone is

have a disc shape, and it is further equipped with a plurality separated from the reaction gas via the hydrogen separating

of circular projections having the same diameter as that of films 4 formed on the inner surfaces of the cylindrical

the through-holes 2 of the porous substrate 1. The flange 9 through-holes 2. The separated hydrogen gas flows as the

has orifices 19 at the centers of the above-mentioned pro- permeated hydrogen gas B out of the outlet 7 through the

jections. The flanges 9, 10 are stuck and fixed to the end 3Q pores 0f the porous substrate 1. Of the mixed gas of the

surfaces of the porous substrate 1, with the projections being reaction gas and an unreacted gas, the unpermeated gas C

inserted into the through-holes 2 of the porous substrate 1. which has not permeated through the hydrogen separating

For a bond between the flanges 9, 10 and the porous films 4 is discharged from the apparatus through the outlet

substrate 1, a heat-resistant inorganic bonding agent can be g for the unpermeated gas.

used, and examples of suitable bonding agents include a 35 hydrogen preparing apparatus shown in FIG. 4, the

cement, a mortar and the like having a thermal expansion reforming catalyst is supported on the surface of the hon

coefficient similar to that of the flanges 9,10, and a glass and eycomb carrier 13 arranged on the upstream side of the

a brazing material having a transition point of 550° C. or porous substrate 1 to form reforming catalyst layers 14

more- instead of supporting the steam reforming catalyst in the

The outer peripheral edge of the flange 9 is airtightly w pores 0f me porous substrate 1, as shown in FIG. 3.

nipped by a gasket or the like and the lugs 17,18 of the lid However, the apparatus of FIG. 4 is different from that of

16 and the container body 15, and the peripheral edge is YIG. 3 in that the porous substrate 1 is supported in an

further fastened and fixed by fixing members 32. overhung state via the flange 9 in the container 5 and a

Furthermore, if necessary, the outer peripheral edge can be cushion means for absorbing the expansion of the porous

fixed by welding. 45 substrate 1 is provided.

In this way, one end of the porous substrate 1 is fixed in ^ order to feed the material gas A to the interior of the

an overhung state to the container 5 via the flange 9. One end cylindrical through-holes 2, the material gas is introduced

of each of the through-holes 2 is connected to the outlet 7 for through the ends of the through-holes and the unpermeated

the separated hydrogen gas B via the orifices 19 of the flange gas is discharged through the other ends thereof. Therefore,

9, and the other ends of the through-holes 2 are airtightly 50 it is required that a hydrogen separator is supported at one

sealed by the flange 10. end m me overhung state in the container 15, and the other

The material gas A is introduced into the hydrogen end of the hydrogen separator is connected to the outlet of

preparing apparatus through the inlet 6 and further fed to the the container. Therefore, the hydrogen manufacturing appa

reforming catalyst layers 3 of the porous substrate 1. A ratus might be damaged by the difference in thermal expan

hydrogen gas component in a reaction gas produced on the 55 sion between the hydrogen separator and the container,

reforming catalyst layers 3 selectively permeates through the However, the outer periphery of the container body 15 can

hydrogen separating films 4, and then flows into the through- be constituted in a bellowslike form to absorb the expansion

holes 2. The separated hydrogen gas B passes through the lid 0f the porous substrate 1 in its axial direction, whereby the

16 and flows out of the outlet 7. The unpermeated gas C hydrogen manufacturing apparatus can be prevented from

flows out of the outlet 8. 60 being damaged by the difference in thermal expansion

The porous substrate 1 can be supported at only one end between the container 5 and the porous substrate 1. The

in the container 5 to absorb, the difference in thermal bellowslike portion suffers the pressure of the permeated

expansion between the container 5 and the porous substrate gas, but this pressure is low, usually in the range of from

1 at a high temperature. Furthermore, the diffusion efficiency negative pressure to 2 kg/cm2 which is lower as compared

of the material gas A into the porous substrate 1 can be 65 with the pressure of the material gas, i.e., several kg/cm2 to

heightened by arranging the outlet 8 for the unpermeated gas 10 kg/cm2, and therefore the force which functions to extend

C on the opposite side of the inlet 6 for the material gas A the bellows can be ignored.