JPS61295205A - Reactor for reforming methanol - Google Patents

Abstract

PURPOSE:To supply necessary heat for reforming with high efficiency and to make a device portable by arranging catalyst layers for reforming methanol and catalyst layers for the combustion of fuel gas alternately and by using a three dimensional reticular metal for the carrier of the combustion catalyst. CONSTITUTION:Catalyst layers 2 for the combustion of fuel gas and catalyst layers 3 for the reforming of methanol are arranged alternately in a reactor main body 1 interposing partition walls 4. The combustion catalyst layers 2 are formed by packing the combustion catalyst supported on a three-dimensional reticular metal such as sponge metal, etc. The combustion catalyst layers 2 are allowed to contact closely to partition walls 4 separating combustion reaction chamber 9 from reforming reaction chambers 10 or to the main body 1. Decomposing zones are held by this mechanism at high temp., and conversion of methanol is improved. Further, the concentration of CO in the produced gas is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a methanol reforming reactor that reformes methanol together with steam to generate hydrogen, and more specifically, a methanol reforming reactor for generating hydrogen for fuel cell power generation or general industrial use. The present invention relates to a methanol reforming reactor which efficiently promotes the reforming reaction between methanol and steam as a supply source, and which can be made compact and portable as a hydrogen supply device.

[Conventional technology]

BACKGROUND ART Conventionally, as methanol reforming reactors, there have been known a one-burner type reactor equipped with a burner as a heat source, and a catalytic type reactor having a reforming catalyst layer and a combustion catalyst layer. Catalytic type reactors have a double-tube structure with a reforming catalyst packed inside and a combustion catalyst packed outside.
Also known are structures in which reforming catalysts and combustion catalysts are alternately arranged in a flat plate shape.

[Problem that the invention seeks to solve]

However, single-burner type reactors have a burner as a heating source, so they are not suitable as compact and portable types, and catalytic type reactors mainly use a pellet-shaped ceramic carrier as the catalyst. Therefore, there was a problem that the heat required for the reforming reaction could not be efficiently supplied.

The present invention was made in view of the above points, and an object of the present invention is to provide a methanol reforming reactor that can efficiently supply the heat necessary for the reforming reaction, and is compact and suitable for transport. It is.

[Means and operations for solving the problems] The methanol reforming reactor of the first invention will be described with reference to the drawings. In a methanol reforming reactor in which methanol is reformed with steam to generate hydrogen, the fuel gas combustion catalyst layer 2 is filled with a combustion catalyst having a three-dimensional network metal as a carrier. It is characterized by being formed by

Further, in the methanol reforming reactor of the second invention, if explained with reference to the drawings, methanol reforming catalyst layers 3 and fuel gas combustion catalyst layers 2 are arranged alternately, and methanol is mixed with steam. In a methanol reforming reactor for reforming and generating hydrogen, a methanol reforming catalyst layer 13 and a fuel gas combustion catalyst layer 2 were formed by filling a catalyst with a three-dimensional network metal as a carrier. It is characterized by

In the present invention, platinum may be used as a catalyst only at the inlet of the fuel gas combustion catalyst layer 2, and a binary catalyst of a methanol combustion catalyst and a hydrogen combustion catalyst is used as the fuel gas combustion catalyst. In this case, it is desirable to support platinum as a methanol combustion catalyst and palladium as a hydrogen combustion catalyst on the same carrier.

The present invention will be explained in detail below. FIG. 1 shows an example of the methanol reforming reactor of the present invention.

A catalyst layer 2 for fuel gas combustion and a catalyst layer 3 for methanol reforming are alternately arranged within the reactor main body 1 with partition walls 4 interposed therebetween, thereby configuring a reactor for methanol reforming.

The combustion catalyst layer 2 is formed by being filled with a combustion catalyst using a three-dimensional mesh metal carrier such as a spongy metal or wire wool, and a partition wall 4 partitions the combustion reaction chamber 9 and the reforming reaction chamber IO.
Or it is in close contact with main body 1.

5 is a fuel gas conduit into which fuel gas and oxygen-containing gas are introduced, 6 is a reforming material conduit into which reforming materials (methanol and hydrogen) are introduced, 7 is a combustion exhaust gas pipe, and 8 is a reformed gas pipe.

The fuel gas introduced from the fuel gas pipe 5, that is, hydrogen or methanol in the waste gas from the fuel cell hydrogen electrode, and oxygen in the waste gas from the fuel cell oxygen electrode react to cause the following exothermic reaction (combustion). occurs, and heat is supplied to the reforming reaction chamber through the partition wall 4 as a heat transfer wall.

H2+ 1/202→H20△H=-68,31ad/
mol (1) CH30H+3/20□-2H20+O
○2ΔH=-17771 cal/mol (2) The catalyst species used here include Pt, Pd%Ru, which is generally well known as a catalyst for combustion of hydrogen and methanol.
○2, Co3O4, Nip, MnO2, etc. may be used, but P is effective in low-temperature ignition of methanol.
A Pd binary catalyst is desirable because it is relatively low cost and effective for hydrogen combustion. However, even though it is a binary catalyst, the supported form of the catalyst does not need to be composed of a binary catalyst of Pt and Pd all over the three-dimensional network metal as a carrier; It is sufficient if pt is supported only in the inlet portion alone or as a binary system with Pd. The reasons for this are: (1) PT is excellent in low-temperature ignitability of methanol, and the temperature can be raised at the time of startup of the reforming reactor only by supplying methanol and air to the combustion reaction chamber.

(2) Although PT is also effective as a hydrogen combustion catalyst, P
dO is more effective, and the price of Pd is 1/2 to 1/3 that of Pt, leading to cost reduction.

This is because it has the following advantages.

Also, N1 and N1-0r as carriers for combustion catalysts.

Spongy metals such as Cu are generally known,
In particular, the reasons for limiting the metal to a three-dimensional network are as follows: (1) Heat obtained by combustion of hydrogen or methanol can be used more effectively for the methanol reforming reaction. In other words, the three-dimensional mesh metal such as a spongy metal serving as a catalyst carrier serves as a heat transfer medium to transfer heat to the partition wall between the reforming reaction chamber and the reforming reaction chamber. For this purpose, it is desirable that the catalyst and the partition wall are in close contact with each other, and it is more effective to make the partition wall and the three-dimensional mesh metal come into close contact with each other by brazing or the like.

(2) The combustion reaction in the combustion chamber is performed more uniformly than with normal pellet catalysts, no hot spots are formed, and the temperature can be made uniform, leading to prevention of deterioration of the catalyst.

(3) It is also possible to equalize the temperature in the reforming reaction chamber, promoting the reforming reaction and at the same time suppressing the production of CO (-carbon oxide).

(4) The catalyst is not destroyed even by the vibrations of the reforming reactor, leading to expanded applications.

etc. can be mentioned.

On the other hand, the reforming catalyst is a pellet-shaped catalyst of CuO, Al2O3, ZnO, Cr2O3, which is effective for the reforming reaction between methanol and steam, or a combination thereof, or a catalyst supported on a three-dimensional network metal such as a spongy metal. is charged, and after reduction, a hydrogen-rich gas is produced by the reaction of methanol and steam.

When methanol is reacted with water vapor at a temperature of 200'C or higher in the presence of the reforming catalyst, a fuel gas containing hydrogen and carbon dioxide as main components is obtained.

This reaction proceeds as an endothermic reaction as shown in equation (3).

OH, OH+H20→CO2+ 3H2ΔH=+11.
81 al/mol (3) This reaction is considered to be a two-stage reaction of the following methanol decomposition reaction (4) and the resulting Co water gas shift reaction (5).

0H30H-+CO+2H2ΔH=+21.61a+l
/mol (4)00+H2O-,00□+H2,d
= -9,8 mol/mol (5) Here, the decomposition reaction of methanol is endothermic, and the shift reaction of CO is exothermic. ) formula is disadvantageous at high temperatures. However, as a hydrogen source for fuel cells, it goes without saying that it is desirable for the hydrogen concentration in the produced gas to be as high as possible, and since CO in the produced gas can poison the electrodes used in fuel cells, It is desirable to reduce this as much as possible. Therefore, it is desirable that the temperature of the reforming reactor be as high as possible near the source gas inlet (decomposition reaction zone) and as low as possible near the product gas outlet (shift reaction zone).

From the above point of view, platinum may be used as a catalyst only at the inlet of the fuel gas combustion catalyst layer 20, and as shown in FIG. It may be provided in 1/3 to 1/2 of the combustion reaction chamber 9. 11 is a porous support.

Furthermore, the reforming catalyst layer 3 and the combustion catalyst layer 2 may be formed by filling a catalyst with a three-dimensional network metal as a carrier. In this case, there is an advantage that thermal efficiency is further improved.

Figure 3 shows the reforming reactor 1 of the present invention configured as described above.
2 is used as a hydrogen supply device for the fuel cell 13. 14 is a pure water supply pump, 15 is a methanol-p supply pump, 16 is a raw material vaporizer, 17 is a raw material preheater, 18
19 is an air supply blower, 19 is a cooling air circulation blower, 20 is a mixer, 21 is a cooling section, 22 is an oxygen electrode, and 23 is a hydrogen electrode.

At startup, methanol is sent to the combustion catalyst layer 2 through the mixer 20 through the line 24, where it is combusted and heated, and then water' from the fuel cell 13; off-gas from the X electrode 23 is sent through the line 24.
5, the fuel is switched and supplied to the combustion catalyst layer 2 via the mixer 20, and steady operation is performed.

〔Example〕

Next, Examples of the present invention and the results of experiments using the methanol reforming reactor of the present invention will be explained.

Example methanol reforming catalyst: CuO: 80 mol%, zn
o: l Q Molk%, Al2O3: 10 motL
A reforming reaction chamber was filled with Berett catalyst 11 having a particle size of 5 mm and having a composition of 1.5 t%. On the other hand, the combustion chamber is filled with a combustion catalyst supporting Pt in a spongy metal base material (Celmet manufactured by Sumitomo Electric), and the reforming reaction chamber: 3 layers and the combustion chamber: 4 layers are arranged alternately as shown in Figure 1. A stacked methanol reforming reactor was constructed.

When starting a reforming reaction using steam and methanol using this reforming reactor, the reforming reaction chamber KN2:
10 vol%-N2: Reduction was carried out by gradually increasing the temperature from room temperature to 250'C in a reducing gas stream consisting of 9 Q vol%. Next, after cooling the reformer to room temperature (approximately 20°C), SV = 5 based on the amount of catalyst packed in the combustion reaction chamber side.
Air was flowed at a rate of 0,0001/A, methanol was supplied into the air flow, and the temperature rise of the combustion catalyst layer was confirmed. Thereafter, the amount of methanol supplied was gradually increased within a range of methanol concentration of 5 vol % or less, and the temperature of the combustion reaction chamber was set at about 250°C. At the same time, a mixed gas of methanol and steam was supplied to the reforming reaction chamber under N20/CH30H conditions via a separately installed evaporator, and N2: approx.
After confirming that %H2-rich gas was generated,
Combustion reaction chamber side 02 concentration: N2 so that it becomes 18 VOI%
- The fuel gas was switched from methanol to N2 Ganu, adjusted by an air mixture. At this time, N2 is supplied from a separately provided cylinder, and SV = 50.000 1/H
Adjusted to.

Furthermore, depending on the amount of hydrogen gas supplied from the cylinder, the temperature at the exit of the reforming reaction chamber of the reforming reactor is set to 200 to 220'C, and the composition of the produced gas is measured using a wet gas meter using a wet gas meter. The methanol conversion rate and CO concentration in the produced gas were determined, and the following results were obtained. At this time, at the same time, the inlet of the combustion reaction chamber,
The temperature at the outlet and the temperature at the inlet and outlet of the reforming reaction chamber were measured.

1st time 2nd time reforming reaction chamber inlet temperature ('C) 260 270
Reforming reaction chamber outlet temperature (°C) 205 215
Combustion reaction chamber inlet temperature ('C) 860 880 Combustion reaction chamber outlet temperature ('C) 210 220 Methanol conversion rate (%) 100 100 C○ concentration in produced gas (%) 0.5 0.9 Determined from the reaction This value is almost close to the equilibrium calculated value.

〔Effect of the invention〕

As described above, the methanol reforming reactor of the present invention uses a combustion catalyst, or a combustion catalyst and a reforming catalyst, based on a three-dimensional mesh metal such as a spongy metal with high thermal conductivity or wire wool. By using a catalyst as a material, the methanol decomposition reaction can be accelerated by intensively supplying combustion heat to the methanol decomposition zone and maintaining a high temperature.

On the other hand, in the downstream part of the reactor (near the produced gas outlet), most of the heat accompanying the combustion of fuel gas is consumed as the heat necessary for decomposing methanol, so the temperature is relatively low (approximately 200 m
°C) to promote the C○ shift reaction equation (5), it becomes possible to lower the CO concentration in the generated gas to the equilibrium value of equation (5).

Although the temperature difference between the inlet and outlet of the reforming reaction chamber varies depending on conditions such as the amount of raw material supplied, it is possible to maintain a temperature difference of around 100°C. It can be said that the reforming reactor has excellent heat transfer because the temperature difference between the side and the reforming reaction chamber side is around 150°C, but it is within several degrees Celsius on the reactor outlet side. These features of the present invention can be summarized as follows.

(1) It becomes possible to maintain the decomposition zone at a high temperature, and it becomes possible to significantly improve the methanol conversion rate.

(2) By lowering the temperature of the 00 shift reaction zone, the shift reaction almost reaches an equilibrium value, making it possible to reduce the CO concentration in the produced gas.

(3) The heat produced during combustion is efficiently used in the reforming reaction, improving the thermal efficiency of the power generation system.

(4) The reformer can be made more compact, leading to improved portability and lower costs.

Another feature of the present invention is that when a binary catalyst composed of Pt-Pd is employed, the startup time of the methanol reforming reactor and even the fuel cell can be significantly shortened, and the fuel cell It is possible to simplify the power generation system. That is, when starting up the conventional reforming reactor and fuel cell, a separate starting burner is provided and the temperature is raised by methanol combustion gas. However, when a binary catalyst consisting of Pt-Pd is used in the reactor of the present invention, air containing methanol vapor is simply supplied to the combustion reaction chamber side of the reforming reactor at startup, and the combustion catalyst is activated. An oxidation reaction occurs, making it easier to raise the temperature of the reforming reactor, and further, by supplying the combustion gas generated in the reforming reactor to the fuel cell, it becomes possible to raise the temperature of the fuel cell. In other words, it can be started easily without the need for a special starting burner. However, in order to achieve this, a combustion catalyst is required that simultaneously ignites stable Hβ combustion and ignites even in air containing dilute methanol at room temperature.
Teasing is especially effective. However, Pt is expensive and Pd is more effective for H2 combustion.
It is advantageous to employ a binary t-Pd catalyst. In other words, by supporting a portion of the spongy metal base material with PT and the remaining portion with Pd, a relatively low-cost catalyst that has both the properties of igniting methanol at room temperature and combusting H2 during startup can be created. Obtainable. However, the Pd catalyst works effectively as a methanol combustor when the temperature rises to a certain degree, so
As a PT catalyst, it is sufficient that the inlet of the reforming reactor serves as a methanol ignition source at startup, and a small amount of fuel is sufficient.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of the methanol reforming reactor of the present invention, Fig. 2 is an explanatory diagram showing another example of the reactor of the present invention, and Fig. 3 is an explanatory diagram showing an example of the reactor for methanol reforming of the present invention. This is a flow sheet when used as a hydrogen supply device. l...Reactor main body, 2...Catalyst layer for fuel gas combustion,
3... Catalyst layer for methanol reforming, 4... Partition wall, 5...
... Fuel gas conduit, 6... Reforming raw material conduit, 7... Combustion exhaust gas pipe, 8... Reformed gas pipe, 9... Combustion reaction chamber, 10... Reforming reaction chamber, 11 ...Porous support, 12
... Reforming reactor, 13... Fuel cell, 14...
Pure water supply pump, 15...methanol supply pump, 1
6... Raw material vaporizer, 17... Raw material preheater, 18...
・Air supply blower, 19... Cooling air circulation blower, 2
0... Mixer, 21... Cooling section, 22... Oxygen electrode, 23... Hydrogen electrode, 24... Line, 25... Line

Claims (1)

[Scope of Claims] 1. A methanol reforming reactor in which methanol reforming catalyst layers and fuel gas combustion catalyst layers are arranged alternately to reform methanol together with steam and generate hydrogen,
A reactor for methanol reforming, characterized in that a fuel gas combustion catalyst layer is formed by filling a combustion catalyst with a three-dimensional network metal as a carrier. 2. A methanol reforming reactor in which methanol reforming catalyst layers and fuel gas combustion catalyst layers are arranged alternately to reform methanol together with steam and generate hydrogen,
A methanol reforming reactor, characterized in that a methanol reforming catalyst layer and a fuel gas combustion catalyst layer are formed by filling a catalyst with a three-dimensional network metal as a carrier. 3. The methanol reforming reactor according to claim 1 or 2, wherein platinum is used as a catalyst only at the inlet of the fuel gas combustion catalyst layer. 4. The methanol reforming reactor according to claim 1 or 2, which uses a binary catalyst of a methanol combustion catalyst and a hydrogen combustion catalyst as the fuel gas combustion catalyst. 5. The methanol reforming reactor according to claim 4, wherein platinum is supported as a methanol combustion catalyst and palladium is supported as a hydrogen combustion catalyst on the same carrier.