JPS6036302A - Separation of hydrogen from gaseous mixture containing hydrogen - Google Patents

Abstract

PURPOSE:To enable the operation of an electrochemical hydrogen separator using an ion exchange resin at high current density, by sufficiently humidifying the hydrogen-containing mixed gas supplied to the anode. CONSTITUTION:The ion exchange resin membrane 1 prepared by introducing sulfonic acid group to a perfluorocarbon resin base is integrated at one surface with the anode 2 and at the other surface with the cathode 3, and is furnished with charge-collecting mesh anode and cathode 4, 5, the terminal plates 6, 7 for the anode and cathode, and the cell frame 8. A gaseous mixture of H2 and N2 is humidified in the humidifying tank 9 to nearly the saturated state, and supplied to the apparatus through the gas inlet 10. When a DC current is passed between the anode 2 and the cathode 3, the selective ionization of H takes place at the anode 2, and at the same time, H2 is generated at the cathode 3. The generated H2 is discharged from the outlet 11, and the residual gas left after the removal of H2 at the anode 2 is discharged through the outlet 12. The separation apparatus can be operated at high current density by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of separating hydrogen from a mixed gas containing hydrogen using an electrochemical method, and its object is to reduce the operating current W! of an electrochemical cell. lff
The purpose is to increase the hydrogen separation rate to increase the hydrogen separation rate.

The operation of separating hydrogen from a hydrogen-containing gas mixture is extremely important in the chemical industry, and is being developed or put into practical use in hopes of finding applications that are currently lacking. (1) Purge gas for 7monium synthesis hydrogen recovery from ). f. (2) recovery of a-filtered hydrogen in the purge gas of a hydrogen production plant; (3) recovery of hydrogen in the waste gas used for petroleum desulfurization.

Conventionally, as the hydrogen recovery operation described above, a method using selective separation of hydrogen using a non-porous polymeric membrane such as a polydimethylsiloxane copolymer membrane has been put into practical use. However, the drawback is that the purity of the hydrogen separated by this membrane separation method is generally not that high.

Although it has not yet been put into practical use, an electrochemical method has already been developed to make the separated hydrogen highly pure. In other words, in the electrochemical method, a gas diffusion pot called a hydrogen tank in a fuel cell is used as a cathode.
An electrochemical cell is constructed by placing a metal similar to that used in water electrolysis as the negative surface, and using a water bath solution of sulfuric acid, perchloric acid, or potassium hydroxide as the electrolyte, and containing hydrogen on the cathode side. When a mixed gas is supplied and a direct current is passed between the positive and negative electrodes, on the anode side, 1(2-1-2oir -42HgQ + 2e (7
Jl/potassium electrolyte) (1) or H2→2[+ 26- (acidic electrolyte) (2), selective electrolytic oxidation of hydrogen occurs, and on the cathode side, the above (Equation 11 or ( 2) A reaction in the opposite direction of the equation occurs,
Highly pure hydrogen gas can be obtained.

The reason why this electrochemical method has not been put to practical use so far is that as long as the above-mentioned aqueous electrolyte is used, the operating current density is at most 100-20. OmA/ci, the reaction rate is slow and the reaction rate is very low.In contrast, recently developed polymers based on F-containing polymers such as f'L1-perfluorocarbons and sulfonic acid-based polymers have been developed in recent years. By introducing a cation-exchange group such as cation-exchange group, using an ion-exchange resin membrane as an electrolyte, and integrally bonding anode and anode electrodes to this membrane, applying T-co fuel cell technology, it is possible to operate at a higher current density. The possibility of an electrochemical separation device for hydrogen has emerged.

However, the inventors of the present invention have conducted various experiments and discovered that this method of ion exchange (using a lipid membrane) has one drawback. In other words, in an electrochemical hydrogen separation device containing an ion exchange resin, the anode reaction is as shown in equation (2) above, but the hydrogen ions (H+) generated in equation (2) move from the In side to the cathode side. When moving, water is depleted at the interface between the ion exchange resin membrane and the ion exchange resin membrane, which is accompanied by several moles of water molecules, making it difficult to operate at a continuous high current density. I discovered the fruit.

The present invention was made based on this discovery, and the hydrogen-containing mixed gas to be supplied to the anode side is sufficiently p1.
Wetting allows operation at large wL flow densities.

Hereinafter, an example of an embodiment of the present invention will be described in detail. [Schematic cross-sectional structure of a vapor chemical hydrogen separation device is shown.]

tllll, t based on perfluorocarbon, with sulfoiso acid group introduced 1. It is an ion exchange resin membrane,
The positive order (2) is attached to one side, and the VA temporary ta+ is integrally attached to the pond side. I'm here. The anode (2) is made of platinum and is joined by electroless plated plate, and the cathode (3) is made of platinum plated plate.
Mixture of powder and polytetrafluoroethylene 1
It consists of ~ and is joined by the hold breath method. (4)
is the positive (Tora current collector network), (5) is the Amata current collector network, and (6) is the anode terminal plate.

(7) is a negative terminal board, and (8) is a cell frame.

A mixed gas of hydrogen and nitrogen at a mixing ratio of 1:3 is humidified pII.
+9+ humidifies until saturated, and the mixed gas inlet (
10). When a current of 1 current is passed between the positive electrode (2) and the negative electrode (3), a selective ionization reaction of hydrogen occurs at the positive electrode (2), and at the same time hydrogen is generated in the negative layer (3). This generated hydrogen is led out from the hydrogen outlet (11). On the other hand, hydrogen is removed at the anode (2) and the remaining gas is led out from the remaining gas outlet (12).

When generated from the cathode, the purity of hydrogen is 99.99%.

Let me explain the effect of non-invention.

Comparing the relationship between the current density and cell voltage of an electrochemical hydrogen separation device (n, y obtained in the above example without using humidification) and that obtained in the case of no particular humidification as in the conventional case (Bl), the second
The result will be as shown in the figure.

In other words, only by humidifying as in the present invention, 1000
It can be seen that it is possible to operate at a flow rate of up to 1500 mA/d, which is about the same as that of one car.

By humidifying a mixed gas containing hydrogen, it is possible to operate at a high current density, in other words, to separate hydrogen more efficiently, and its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an electrochemical hydrogen separator according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of an electrochemical hydrogen separator according to an embodiment of the present invention and a conventional product (11). It is a diagram showing a comparison of the relationship between the current WI degree and the cell voltage. ■...Ion exchange JhRilRL, 2...
・Anode. 8... cathode, 4... cathode current collection network, 5...
...Cathode current collector network, 6...Anode terminal plate, 7
・・・・・・Terminal board, 8・・・Cell frame, 9・・Moisture n. 10...Mixed gas inlet, 11...Hydrogen outlet. I2...Residual gas outlet.

Claims (1)

[Claims] Hydrogen is attached to the anode side of an electrochemical cell, which is made of a fluorine-containing 10,000-molecule molecule and has a cation exchange group introduced into it.The cathode is integrally bonded to one side of a hydrogen ion transfer type ion exchange resin membrane, and the anode is bonded to the other side. By humidifying a mixed gas containing A method for separating hydrogen from a hydrogen-containing gas mixture characterized by a filter.