JP2852320B2 - Method for removing carbon monoxide from reformed gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for efficiently removing carbon monoxide in a reformed gas generated by a reforming reaction of methanol. When a reformed gas is used as a fuel gas of a fuel cell having a low operating temperature such as a polymer electrolyte fuel cell, it is necessary to remove carbon monoxide poisoning a fuel cell electrode to an allowable value. The present invention provides a method for efficiently removing carbon monoxide in a reformed gas so that the reformed gas can be suitably used as the fuel gas.

[0002]

2. Description of the Related Art A reformed gas generated by a methanol reforming reaction contains about 1% of carbon monoxide.
When this is used as a fuel gas for a polymer electrolyte fuel cell, 10 ppm of carbon monoxide is used due to its low operating temperature.
Need to be removed. Many methods have been proposed for the removal, such as a select oxo method and a membrane separation method. In the selectoxo method, it is necessary to mix air or the like in the fuel gas, and in the membrane separation method, the pressure on the fuel gas side needs to be maintained at a high pressure of several tens of bars.

[0003] Hydrogen refining by the methanation method is widely used in refineries and the like. After pretreatment of reformed gas, not only carbon monoxide but also carbon dioxide is reduced to a concentration of about several percent. This is a method for simultaneously removing both components in an adiabatic reactor, and is intended to produce high-purity hydrogen.

In the method of removing carbon monoxide by the select oxo method, which has been proposed as a pretreatment of a fuel gas for a polymer electrolyte fuel cell, it is necessary to mix an oxidizing agent such as air into the fuel gas. Care must be taken when adjusting the parameters. Further, in the hydrogen purification by the membrane separation method, the pressure on the fuel gas side needs to be maintained at a high pressure of several tens of bars, and high-pressure equipment is required.

[0005]

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to prevent the above-described problems of the select oxo method and the membrane separation method from occurring, and to prevent the use of an oxidizing agent or the like for the reformed gas. It is an object of the present invention to provide a method capable of efficiently removing carbon monoxide in a reformed gas without requiring the use of additives or equipment for high pressure.

[0006]

Means for Solving the Problems When comparing the methanation reaction between carbon monoxide and carbon dioxide in a reformed gas, the present inventors proceed with the methanation reaction of carbon monoxide with much higher priority. Focusing on this fact, a methanation reaction test using a Ni-based catalyst was performed on the reformed gas resulting from the methanol reforming reaction, and as a result, the concentration of carbon monoxide was reduced to the reference value by appropriately adjusting the set temperature. The inventors have found that it can be reduced, and completed the present invention.

In the method for removing carbon monoxide from a reformed gas according to the present invention, carbon monoxide in a reformed gas generated by a methanol reforming reaction is removed by a methanation reaction in the presence of a Ni-based catalyst. In the method, the set temperature is set to 2
The space velocity (SV value) is in the range of 40 to 250 ° C and 300 to
The carbon monoxide is preferentially subjected to a methanation reaction while being maintained in the range of 500 h ^-1 , and the catalyst particles are mixed with ceramic balls or the Ni content in the catalyst is adjusted to generate heat by the reaction. And the reaction temperature is maintained in the above range.

[0008] Set temperature range 2 for the methanation reaction
The temperature of 40 to 250 ° C. is included in the temperature range of 200 ° C. or higher at which nickel carbonyl which is toxic to the human body is not generated and 250 ° C. or lower which is the heat source temperature of the reformer.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The method according to the invention is illustrated by the flow sheet of FIG. In FIG. 1, first, methanol and steam are introduced into a reformer (1) to perform a methanol reforming reaction. A heat medium circulation type reactor is used as the reformer (1), and is heated by a heat medium, for example, exhaust gas sent from a combustor (4) described later as a heat source. Reformer
The reformed gas from (1) is about 1% carbon monoxide, about 22%.
% Carbon dioxide and about 10% water vapor. This reformed gas is introduced into the carbon monoxide remover (2) for performing a methanation reaction without any pretreatment. In this embodiment, a heat medium circulating reactor is employed as the carbon monoxide remover (2) to facilitate temperature control. The carbon monoxide remover (2) is filled with a Ni-based catalyst.
In the carbon monoxide remover (2), set the temperature to 240 to 2
50 ° C range, space velocity (SV value) 300-500h
Maintaining each in the range of ^-1 , carbon monoxide in the reformed gas is preferentially reacted by the methanation reaction, and its concentration is reduced to a specified value or less. The Ni content in the catalyst is about 20% by weight, and this content is determined so as to suppress the heat generation due to the methanation reaction and maintain the reaction temperature in the above range.

Thus, the reformed gas from which carbon monoxide has been removed is extracted from the bottom of the carbon monoxide remover (2), sent to a polymer electrolyte fuel cell, and supplied to the fuel gas.

The heat medium discharged from the reformer (1) is passed through a carbon monoxide remover (2), and then returned to a combustor (4) by a heat medium circulation pump (3), where fuel is removed. The temperature is raised by burning off-gas from the battery and sent to the reformer (1) again as a heat source. By passing at least a part of the heat medium through a short circuit that does not pass through the carbon monoxide remover (2),
The temperature of the carbon monoxide remover (2) can be maintained in the above range.

FIG. 2 is a graph showing the result of removing the concentration of carbon monoxide in the reformed gas by the methanation reaction.

From this graph, it is possible to change the set temperature from 240 to 250.
It can be confirmed that the carbon monoxide concentration in the reformed gas can be reduced to 10 ppm or less by performing the methanation reaction while maintaining the range of ° C and the space velocity (SV value) within the range of 300 to 500 h- ^1. Was.

Further, the catalyst particles are mixed with a ceramic ball three times in weight, and the mixture is mixed with a carbon monoxide remover.
By filling in (2), heat generation due to the methanation reaction is suppressed, and the set temperature is set to 250 ° C and the space velocity (SV
Value) was maintained at 300 h ^-1 , respectively, except that the same operation was performed. The temperature change of the catalyst layer in this case is shown in the graph of FIG.

From this graph, it was confirmed that the catalyst particles can be diluted with the ceramic balls as described above to suppress a rise in the temperature of the catalyst packed bed by about 20 ° C. at the maximum.

[0016]

According to the method for removing carbon monoxide from reformed gas according to the present invention, the set temperature is in the range of 240 to 250 ° C.
Since the space velocity (SV value) is maintained in the range of 300 to 500 h ^-1 and carbon monoxide is preferentially subjected to the methanation reaction, the use of additives such as an oxidizing agent in the reformed gas and equipment for high pressure is used. , The carbon monoxide in the reformed gas can be efficiently removed, and the apparatus for removing carbon monoxide can be simplified.

Further, by mixing the catalyst particles with the ceramic balls or adjusting the Ni content in the catalyst, the heat generation due to the above reaction can be effectively suppressed, and the reaction temperature can be appropriately maintained in the above range. . Therefore, it is possible to reliably suppress the occurrence of a side reaction from carbon dioxide to carbon monoxide due to an unnecessary increase in the temperature of the catalyst packed bed.

[Brief description of the drawings]

FIG. 1 is a flow sheet illustrating the method according to the present invention.

FIG. 2 is a graph showing a relationship between a set temperature and a carbon monoxide concentration.

FIG. 3 is a graph showing a relationship between a catalyst layer length and a temperature.

[Explanation of symbols]

 (1): Reformer (2): Carbon monoxide remover (3): Heat medium circulation pump (4): Combustor

Continuation of the front page (72) Inventor Rikio Shinohara 5-3-28 Nishikujo, Konohana-ku, Osaka-shi Inside Tachibashi Shipbuilding Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C01B 3/58 B01J 23/755 C10L 3/10 H01M 8/06 H01M 8/10

Claims (2)

(57) [Claims] 1. A method for removing carbon monoxide in a reformed gas generated by a methanol reforming reaction by a methanation reaction in the presence of a Ni-based catalyst, wherein a set temperature is in a range of 240 to 250 ° C. Speed 300-500h
^The carbon dioxide is preferentially subjected to a methanation reaction while maintaining each in the range of ^-1 , and the heat generated by the above reaction is reduced by mixing the catalyst particles with ceramic balls or adjusting the Ni content in the catalyst. A method for removing carbon monoxide from a reformed gas, wherein the reaction temperature is kept within the above range while suppressing the reaction temperature. 2. The method according to claim 1, wherein the reformed gas is a gas for use as a fuel gas in a polymer electrolyte fuel cell of a marine electric propulsion system.