JPS6291402A - Methanol reformer - Google Patents

Abstract

PURPOSE:To prolong the life of a catalyst and to keep the reforming efficiency at a high level by packing the catalysts having different activities in the raw gas inlet part and the outlet part for the gaseous reaction product of the catalyst bed in a reformer in reforming methanol with steam. CONSTITUTION:The catalyst resistant to heat and having activity at high temp. is packed in the raw gas inlet part of the catalyst bed in the reformer and the catalyst having activity at low temp. is packed in the outlet part of the gaseous reaction product in the steam-reforming of methanol. A Cu-Cr-Zn catalyst is used as the catalyst resistant to heat and having activity at high temp. and a Cu-Zn catalyst is preferably used as the catalyst having activity at low temp. Since the catalysts are packed in such a way, the temp. distribution at the inlet part is raised as high as possible and that at the outlet part is lowered as low as possible, and the above-mentioned effect can be obtained.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is incorporated into a fuel cell system to
The present invention relates to a fuel reformer that hydrogenates water mixed gas to reform it into thigas and supplies it to a fuel cell.

[Prior art and its problems]

In order to use methanol as a fuel for fuel cells, it is necessary to gasify the liquid raw material, hydrogenate it, reform it to thigas, and send it to the fuel cell.For this purpose, the fuel cell system requires a fuel reformer. is included. Here, a conventional fuel cell system of this type will be explained with reference to FIG. In the figure, 1 is a fuel cell, and 2 is a raw material tank 7 containing a liquid raw material mixed with methanol and water, which is a vaporizer. A fuel reformer 3, which is the object of the invention, is installed as an intermediary. Such a fuel reformer □3 is burner 4
A reforming reaction tube 6 is built into the combustion chamber of the furnace vessel 5 equipped with a fuel cell 1, which converts fuel gas into hydrogen through a contact reaction with a catalyst and reformes it into gas. Supply 4.

This heat is used to reform the gas and vaporize the methanol/water mixture. Reference numeral 8 is a liquid fuel supply pump, 9 is a blower that supplies air as an oxidant reaction gas to the fuel cell 1, and 10 is a blower that sends air for cooling the fuel cell.

Incidentally, the steam reforming reaction of methanol occurs under milder conditions than the steam reforming of methane, butane, and the like. Generally %200-300℃, water vapor.

It is carried out under the conditions of a methanol molar ratio of 1.0 to 2.0, and is said to consist of the following two-stage elementary reaction.

CH30H-+CO+2H2...Song/Song ■C
O+H20kon”02+H2・・・・・・・・・・
・・・・・・・・・・・・■CH30H10H20→ CO
2+3Hz ・・・・・・・・・・・・・・・・・・
... ■■ is an endothermic reaction, ■ is an exothermic reaction, and in total, ■ is an endothermic reaction. For this reason, the methanol reformer is either an external heat exchange type isothermal reactor that supplies heat from the outside of a reaction tube filled with a catalyst, or a methanol reformer that is used as a raw material.
There are adiabatic reactors that heat the water mixed gas above the reaction temperature and provide reaction energy with sensible heat, and there are reactors that are intermediate between the two. In an isothermal reactor, thermal energy must be exchanged between the catalyst layer and the outside, and temperature distribution tends to occur in the radial direction of the packed bed, and energy cannot be transferred if the radius is increased beyond a certain radius.

Further, a drawback of the adiabatic reactor is that the activity of the Cu-Zn catalyst filled inside the reactor rapidly deteriorates when the temperature exceeds 300°C. (In Figure 2, characteristic a indicates the catalyst life characteristic of the Cu-Zn catalyst.) In other words, the thermal energy that the methanol/water mixed raw material gas can bring in as sensible heat depends on the H20/MeOH-e Al ratio. However, when H207Me OH = 2, it is about 10% of the energy required for reforming. H20/M
Increasing the molar ratio of eOH to 2 or more can shift the equilibrium of the reaction (2) to the right, but energy for vaporizing water must be provided in the vaporizer, and the reformed gas There is a drawback that the internal 82 partial pressure decreases, resulting in a decrease in battery characteristics and a decrease in the efficiency of the entire system.

[Purpose of the invention]

The purpose of the present invention is to make a single isothermal type reactor closer to an adiabatic type by making the inlet portion of the catalyst bed a catalyst that can withstand higher temperatures, simplify the structure of the catalyst packed bed portion, and reduce the temperature of the inlet portion of the catalyst bed. The purpose is to make the reforming reaction more advantageous and reduce the frequency of catalyst replacement by increasing the

[Key points of the invention]

In a methanol reformer using a packed bed catalyst reactor, the inlet part of the catalyst packed bed for the methanol/water mixed raw material gas is filled with a heat-resistant catalyst that can be used even at high temperatures, and the outlet part is filled with a heat-resistant catalyst that can be used even at high temperatures. By charging a harsh catalyst at a low temperature, the CO concentration in the reformed gas is kept low, the methanol reforming rate is not reduced, and the life of the catalyst is extended.

[Embodiments of the invention]

FIG. 1 shows the configuration of a fuel reformer according to an embodiment of the present invention, and members corresponding to those in FIG. 3 are given the same reference numerals. That is, the burner 4 is located in the upper center of the furnace vessel 5.
is installed, and a combustion chamber 14 partitioned by an intermediate partition wall 13 is defined below it.

The lower end of the combustion chamber 14 communicates with a chamber defined on the outer periphery of the partition wall 14, and the upper portion of the chamber communicates via a combustion exhaust gas manifold 15 with an exhaust pipe 16 leading to a chimney. Note that the burner 4 is equipped with a fuel cell off-gas supply pipe 17.
and a combustion air supply pipe 18 are connected.

Further, a plurality of reforming reaction tubes 6 connected to the circumference of the fuel gas manifold B and filled with a reforming catalyst in a metal pipe are arranged around the outer circumference of the combustion chamber 14, and each reforming reaction tube 6
is connected at its upper end to a reformed gas supply pipe B which leads to the fuel cell via a reformed gas manifold.

With the above configuration, the combustion gas combusted in the burner 4 descends in the combustion chamber 14 as indicated by the chain arrow G, wraps around from the lower end of the chamber to the outer peripheral chamber of the partition wall 13, and is reformed in the process of rising from there. Heat is exchanged with the reaction tube 6, and the exhaust gas is exhausted from the exhaust pipe 16 through the manifold 15 to the outside of the thread. On the other hand, after being vaporized in the vaporizer 7, the liquid raw material enters the reforming reaction tube 6 via the supply pipe 21 and the manifold n as shown by arrow F.

In the reforming reaction tube 6, the gasified fuel gas undergoes a reforming reaction through contact with the catalysts 23a and Z3b at high temperature, converting into hydrogen, and becoming a hot reformed gas. After that, it is sent to the fuel cell body.

In such a methanol reforming reactor, a Cu-Cr-Zn catalyst 23b, which has poor activity at low temperatures but is heat resistant, is loaded up to the height of the lower third of the reforming reaction tube 6,
The remaining upper two-thirds of the height is filled with a Cu-Zn catalyst 23a which has excellent activity at low temperatures but poor heat resistance, and the reforming reaction is carried out at the same operating temperature. The life characteristics are shown in Figure 2. As is clear from the figure, the deterioration of the methanol reforming rate is smaller in case b than in case a.

〔Effect of the invention〕

As explained above, according to the present invention, a Cu-Cr-Zn-based catalyst has poor activity at low temperatures but is heat resistant, and a Cu-Zn-based catalyst has excellent activity at low temperatures but has poor heat resistance. By using a catalyst, the temperature distribution of the catalyst layer is actively made higher at the inlet and lower at the outlet, which increases the life of the reforming catalyst and maintains a high reforming rate. I was able to do that.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a methanol reforming reactor according to the present invention;
FIG. 2 is a graph showing changes over time in the methanol reforming rate using the reforming reactor of the present invention and the conventional reforming reactor, and FIG. 3 is a system flow diagram showing a fuel cell power generation device using steam reformed methanol gas. 3... Reformer, 4... Burner, 5... Furnace vessel,
6... Reforming reaction tube, Oa... Cu-Zn based catalyst, 2
3b...Cu-Cr-Zn based catalyst. Sai 1 Illustration Sai 2 Illustration

Claims (1)

[Claims] 1) In a methanol reforming reactor in which a raw material gas consisting of methanol and water vapor is passed through a catalyst packed bed to be reformed into a hydrogen-rich gas, the raw material for the catalyst bed in the methanol reforming reactor is A methanol reforming reactor characterized in that the gas inlet section is filled with a heat-resistant catalyst that is active at high temperatures, and the outlet section is filled with a catalyst that is active at low temperatures. 2) In the product described in claim 1, the heat-resistant catalyst that is active at high temperatures is a Cu-Cr-Zn catalyst, and the catalyst that is active at low temperatures is a Cu-Zn catalyst. methanol reforming reactor.