JPS6036303A - Production of mixed gas containing hydrogen in definite concentration - Google Patents

Abstract

PURPOSE:To produce a hydrogen-containing mixed gas having a hydrogen concentration of high industrial value, by removing hydrogen at the anode of an electrochemical hydrogen-separation apparatus using an ion exchange resin, and utilizing the residual gas left after the separation of hydrogen. CONSTITUTION:An ion exchange resin membrane 1 prepared by introducing sulfonic acid group to a perfluorocarbon resin base is integrated at one surface with the cathode 2 and at the other surface with the anode 3, and is furnished with the charge collectors 4, 5 for the anode and cathode, the terminal plates 6, 7 for the anode and cathode, and the cell frame 8. The primary mixed gas having relatively high H2 concentration and humidified to the saturated state is introduced into the cell through the gas inlet 9, and a DC current is passed through the terminal plates 6, 7. H is ionized at the electrode 3, and H2 is generated at the electrode 2. The generated H2 is discharged through the outlet 10. The secondary mixed gas having relatively low hydrogen concentration and left after the partial consumption of H2 at the electrode 3 is discharged through the outlet 11. Since the H2 concentration of the objective gas is a function of the H2 concentration of the primary mixed gas, the rate of feeding and the operating electrical current, the variables are controlled to attain a constant H2 concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of converting a mixed gas containing a relatively high concentration of hydrogen to a mixed gas containing a relatively low concentration of hydrogen at a predetermined concentration. The present invention relates to a method for producing M, and its purpose is to provide a method for efficiently and easily producing a mixed gas containing hydrogen at a predetermined concentration using an electrochemical method.

In recent years, there has been active research into methods for producing basic chemicals using carbon monoxide and other raw materials, which is referred to as ``CI chemistry''1. In this "C1 chemistry", an important issue is how to adjust the mixing ratio of -carbon oxide and hydrogen to a desired value.

For example, the mixing ratio of carbon monoxide and hydrogen in coke oven gas is 1:10, but this mixing ratio is 1:31C.
From an industrial perspective, how to produce synthetic natural gas called L1-8NG is extremely complicated.

Conventionally, the mainstream methods for separating hydrogen from a Fr-containing mixed gas have been the sample separation method using a porous membrane and the molecular sieve method, but these methods are still technologically mature. However, the running costs are not necessarily cheap either.

On the other hand, Langer and Elaldeman (5ci
ence 142 + 225 (1968)) is a mixed gas containing hydrogen, such as 24% methane, 3% ethylene, and 18% carbon monoxide.

It has been reported that hydrogen can be selectively separated from city gas, which consists of 55% hydrogen, using an electrochemical method.

This electrochemical method uses a gas diffusion electrolyte, so-called hydrogen oxide, which is commonly used in fuel cells.
0, negative (゛・Using a hydrogen generating layer for water electrolysis, a hydrogen-containing gas mixture is supplied to the anode of an electrochemical cell using sulfuric acid as the electrolyte.

When a direct current is passed between the positive electrodes at a current density of about 60 mA/cd, only hydrogen is selectively ionized as shown in equation (1), which is missing in the 4th order, and 11.2 → 2H" + 2e- (1) It utilizes the principle that hydrogen of considerably high purity cannot be obtained by applying equation 21 to the negative side.

211+2e -1 (2(2+) This chemical oxygen separation method has the advantage that it has better selectivity for hydrogen separation than the aforementioned bee separation method or molecular tube method.

The present invention uses this electrochemical hydrogen separation method to obtain a predetermined fA
The aim is to obtain a mixed gas containing 30% of hydrogen.

In the electrochemical hydrogen separation method, the hydrogen separation rate is proportional to the N current flowing, and the power consumption needs to be improved in proportion to the operation t8E. From this point of view, Langer's
The performance of the electrochemical element separation device (60 mA/cm@, m density, 990 mV electrician) seen in the experimental results cannot be expected to be put to practical use.

On the other hand, in recent years, ion exchange resins using fluorine-containing polymers such as perfluorocarbons and introducing cation exchange groups such as sulfonic acid groups and carboxylic acid groups into them have been developed to create ion exchange resins that transfer f7-me ions. A fuel cell and a water electrolyzer that use a membrane as an electrolyte and exhibit excellent f-copolarization characteristics have been developed.1 Combining the hydrogen problem of this type of fuel cell with the hydrogen generating electrode of a water electrolyzer, it is possible to improve practicality. Expect some electrochemical hydrogen separation equipment.

The present invention has been made with this point in mind as one of the points of view.

On the other hand, the above-mentioned 1.anger et al. uses high purity hydrogen generated from the cathode side as the target object, and does not pay any consideration to the remaining gas after the hydrogen is separated and removed at the cathode side. In other words, Langer et al. view electrochemical hydrogen separation devices only as hydrogen concentrators or hydrogen generators.

On the other hand, in the present invention, the hydrogen generated from the anode side is rather a by-product, and the main purpose of the present invention is to focus on the reaction on the partition side (7. The aim is to obtain a hydrogen-containing mixed gas with a high hydrogen concentration, and this is where the bold 4C feature of the present invention lies.
A matching gas containing relatively high hydrogen is supplied to the anode side of an electrochemical cell in which the cathode and anode are integrally bonded to this membrane. If by passing a direct current through the vapor chemical cell, some of the hydrogen in the mixed gas is transferred to the cathode side, and the remaining mixed gas containing relatively low concentration hydrogen is obtained from the 1st electrode side. The hydrogen concentration of the mixed gas containing relatively low-concentration hydrogen as the target gas derived from the anode side is higher than that of relatively high-concentration hydrogen as the partial gas supplied to the cathode side. It is a function of the hydrogen concentration of the containing gas, the supply rate and the operating current.

However, in order to make the hydrogen concentration of the IC gas derived from the electrode plate side reach the desired value, it is necessary to accurately control the operating parameters as described above. To manage the hydrogen concentration of the target gas, detect the hydrogen concentration of the target gas with a hydrogen concentration meter, and determine the current value to be applied or the current value to be applied so that the hydrogen concentration reaches the desired value.
A simple method is to control the tlEffi value. For example, if the hydrogen concentration in the target deriving gas is too high than the desired value, you can reduce the current value or the applied electrons; on the other hand, if it is too low, the current value or increase the applied voltage. Such a method of controlling the hydrogen concentration is also one of the important features of the present invention.The heart of the electrochemical hydrogen separation device of the present invention is that the cathode and the anode are integrally bonded to the ion exchange resin membrane to form a composite body. be. The ion-exchange resin membrane is made by introducing a cationic group, preferably a sulfonic acid group or a carboxylic acid group, or both into a -7 elemental polymer, preferably a perfluorocarbon.
I can't use this thing. The cathode is formed by bonding platinum to an ion exchange resin membrane using an electroless plating method, or by bonding a mixture of platinum plate and polytetrafluoroethylene to an ion exchange resin membrane using a hot pressing method. It is better. The anode is preferably made of a mixture of catalytic metal and polytetrafluoroethylene, and is bonded to the ion exchange resin membrane by hot pressing. Platinum is used as the melting medium. It is important to use a material that is not easily poisoned by carbon monoxide.

It may also be effective to form a layer of a mixture of carbon powder and polytetrafluoroethylene on top of the mixed layer of catalyst metal and polytetrafluoroethylene. When bonding to a resin membrane using the photo-nodobreath method, sulfonic acid groups are introduced into ion exchange resin powder or styrene-divinylbenzene copolymer, which is based on perfluorocarbon and has cation exchange groups introduced. It is also an effective method to mix an ion exchange resin powder formed by the above into the tW layer. When such a method is adopted, the contact area between the electrode and the ion exchange resin that is the electrolyte becomes larger, so generally each polarization and polarization of the electrode plate is
Characteristics are improved.

When a vapor chemical hydrogen separation device is operated using such a bonded body, the hydrogen ions (H+) generated at the anode according to the above equation (1) pass through the ion exchange resin membrane from the anode side to the cathode side. However, at this time, the hydrogen ions are accompanied by several moles of water molecules, resulting in a shortage of water at the interface between the anode and the ion exchange resin, deteriorating the polarization characteristics of the electrochemical hydrogen separation device. . An effective way to prevent this phenomenon is to sufficiently humidify the mixed gas containing hydrogen with a relatively high hydrogen concentration that should not be supplied to the corners. Such humidification operation is one of the important features of the present invention, and on the other hand, the ion exchange resin membrane used in the present invention functions as an electrolyte only after it becomes hydrated.
It is important that the water is as pure as possible; if metal ions are included in the gas supplied from the anode side, hydrogen ions in the ion exchange resin may be replaced with metal ions. The reactions according to the above-mentioned equations (1+ and (2)) rapidly slow down.However, if metal is mixed in the gas supplied, it is necessary to remove it as much as possible.

An electrochemical hydrogen separation device is usually constructed from a plurality of electrochemical cells, but the feed gas may be fed to the plurality of electrochemical cells in parallel or in series, in other words in a multi-stage manner. Although a method of sequentially reducing the hydrogen concentration may be adopted, the former method is preferable because it allows each electrochemical cell to operate equally.

An embodiment of the present invention will be described in detail below.

Fig. 1 is a schematic cross-sectional structure diagram of a unit electrochemical cell that constitutes a part of a 111% chemical hydrogen separation device according to an embodiment of the present invention, and Fig. 2 is a schematic cross-sectional diagram of a unit electrochemical cell that constitutes a part of a 111% chemical hydrogen separation device according to an embodiment of the present invention. A complete system diagram is shown below.

In Figure 1, (1) is an ion exchange resin membrane made of perfluorocarbon as a base and introduced with sulfonic acid groups, (2) is a cathode made of platinum, and (8) is platinum black powder and styrene-divinyl. r, l[, which consists of a mixture layer of ion exchange resin powder obtained by introducing a sulfonic acid group into a benzene copolymer and polytetrafluoroethylene. The cathode (2) is bonded to the ion exchange resin membrane tl+ by an electroless plating method, and the anode (3) is bonded to the ion exchange resin membrane (1+) by a hot press method.

(4) is an anode current collector made of expanded metal of titanium plated with platinum, and (5) is an anode current collector made of expanded metal of titanium plated with platinum. A cathode gas chamber is located in the gap between the cathode current collector (4).
Isaka current collector (an anode gas chamber is formed in a 5 inch gap. (6) is a cathode terminal plate made of a titanium plate.

(7) is an anode terminal plate made of a titanium plate. (8) is a cell frame made of polypropylene.

In this electrochemical cell, a part of the mixed gas that is humidified to saturation and contains a relatively high concentration of hydrogen is supplied to the gas supply port (9).
The cathode terminal plate (6) and the anode terminal plate (7) are
), when a current is passed from an external power supply between the
), a hydrogen ionization reaction occurs, and a hydrogen generation reaction occurs at the cathode 2], and this hydrogen is led out from the hydrogen outlet (10). On the other hand, some hydrogen is consumed at the anode (3): n, r,:
The remaining mixed gas containing hydrogen at a relatively low concentration is led out from the secondary gas outlet (11).

Next, in FIG. 2, (13) is an electrochemical hydrogen separation apparatus in which a plurality of electrochemical cells of the unit shown in FIG. 1 are assembled. - Coke oven gas with a volume ratio of carbon oxide and hydrogen of 1:10 is first humidified to saturation at 14 °C, -
The next gas is distributed by the gas manifold (15) and supplied to the electrochemical hydrogen separator (13). When the current is applied tL, some hydrogen in the coke oven gas is separated and the hydrogen gas manifold (1
At the same time, hydrogen is consumed from the coke oven gas and synthetic natural gas with a volume ratio of carbon monoxide to hydrogen of 3 is collected and extracted in the secondary waste manifold (■8). reactor.

The secondary gas manifold (18) has a hydrogen concentration i (1
9) is installed, and this hydrogen! The interrogator (19) detects hydrogen in the secondary gas manifold (■8), and the signal is sent to the controller (16), which detects carbon monoxide and hydrogen in the secondary gas manifold (18). The electrochemical 7
The "6L flow value supplied to the elementary I4 device bench (13) is controlled by the controller (16).

An example of specific operating conditions for the system shown in FIG. 2 will be briefly described.

First, the Tcomi vapor chemical hydrogen separation device used is L
The unit of action area of dm2 is 1.
It consists of 6 cells stacked and F-coll. This electrochemical hydrogen separator was supplied with 1 QNm of coke oven gas for 1 hour to bring the dew point to 60°C with mW, and was operated with a DC current of 100 A. The voltage of the hydrogen separator (connected in series to the electric model) is 4.8
Atsufko in V. The amount of 7 to 39 gas derived from the hydrogen guide U40 is 5.4 Nm per hour per hour, and the amount of synthetic natural gas obtained from the secondary gas outlet is [hour per hour per 3 .(i Nm and one piece.

As detailed above, the present invention provides a very simple method for producing a mixed gas containing a relatively low concentration of hydrogen from a mixed gas containing a relatively high concentration of hydrogen, and its industrial value is Extremely large.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional structure diagram of a unit electrochemical cell that constitutes a part of an electrochemical hydrogen separation device according to an embodiment of the present invention;
FIG. 2 shows a system diagram of a system for producing synthetic natural gas from coke oven gas according to an embodiment of the present invention. ■...Ion exchange resin membrane, 2...Cathode. 3... Intestine arrangement, 4... Anode current collector,
5... Anode current collector, 6... Negative terminal board, 7
・・・−・Anode terminal plate. 8...Cell frame, 9...-z gas supply port. 10...Hydrogen outlet, 11...Secondary gas outlet. 13...Par direct gas chemical hydrogen separation equipment, 14...
··humidifier. I5...-Next gas manifold, 16...
...Controller, [7...Hydrogen gas manifold. [8... Secondary gas manifold, 19...
...Hydrogen concentration meter.

Claims (1)

[Scope of Claims] 1. A cathode is integrally bonded to one side of a hydrogen iodine transfer type ion exchange resin membrane which is based on a fluorine-containing polymer and has a cation exchange group introduced thereto, and a cathode is integrally bonded to the other side. It consists of a bonded body, a cathode gas chamber, an anode gas chamber, a hydrogen outlet, a supply port for a mixed gas containing a relatively high concentration of hydrogen, and an outlet for a mixed gas containing a relatively low concentration of hydrogen. In the filtration electrochemical hydrogen separation device, a mixed gas containing a relatively high concentration of hydrogen is humidified and supplied from the supply port of the mixed gas containing a relatively still high concentration of hydrogen, and the electrochemical By passing a direct current between the cathode and the rfIJ electrode of a commercial hydrogen separator, a portion of the hydrogen in the mixed solution containing a relatively high concentration of hydrogen is electrochemically transferred from the anode side to the cathode side. hydrogen is extracted from the hydrogen outlet, and the remaining mixed gas containing hydrogen at a relatively low concentration is extracted from the outlet for the mixed gas containing hydrogen at a relatively low concentration. A method of producing a mixed gas containing #1 degree hydrogen. 2. Detect the hydrogen concentration in the mixed gas containing relatively low concentration of hydrogen derived from the outlet of the mixed gas containing relatively low concentration of hydrogen with a hydrogen concentration meter, and check that the hydrogen concentration of the derived gas is A mixed gas containing hydrogen at a concentration as set forth in claim 1 is obtained by controlling the current value to be applied or the tFE value to be applied to the electrochemical hydrogen separation device so as to have a predetermined degree a degree. How to manufacture.