JP6895561B2 - Desulfurizer for fuel gas - Google Patents

Description

The present invention relates to a desulfurizer for fuel gas.

Fuel gases such as city gas, liquefied petroleum (LP) gas, and natural gas contain lower hydrocarbon gases such as methane, ethane, propane, and butane, so they can only be used as industrial fuels and household fuels. It is also used as a raw material for the production of hydrogen.

In the steam reforming method, which is one of the industrial production methods of hydrogen, the above-mentioned lower hydrocarbon gas is reformed by adding steam in the presence of a catalyst to reform the hydrogen as a main component. Generate gas. However, when the catalyst used in the steam reforming method is poisoned by a sulfur compound, the catalytic function deteriorates.
For example, in the case of a fuel cell system, not only the catalyst of the reformer but also the electrode catalyst in the power generation cell is affected by poisoning by the sulfur compound. Therefore, the sulfur compound contained in the fuel gas can be reduced as much as possible in advance. It is desirable to remove it. Generally, in a fuel cell system, sulfur compounds contained in a fuel gas are removed using a desulfurizer.

As the desulfurization method, a room temperature adsorption desulfurization method, a hydrodesulfurization method and the like are known. The room temperature adsorption desulfurization method is a desulfurization method in which a gas is circulated in a container filled with a desulfurization agent at room temperature, and a sulfur compound contained in the gas is physically or chemically adsorbed on the surface of the desulfurization agent. , It is often used because it is easier to operate than the hydrodesulfurization method.

As a desulfurization technique of the room temperature adsorption desulfurization method, many techniques of using a metal-supported zeolite as a desulfurization agent have been reported.
For example, as a desulfurizing agent that simultaneously adsorbs and removes sulfides and mercaptans in fuel gas such as city gas, LP gas, and natural gas, an adsorbent for removing sulfur compounds in which silver is supported on Y-zeolite by ion exchange ( So-called silver-supported zeolites) have been reported (see, for example, Patent Document 1).
In addition, a multi-stage desulfurization method has been reported in which a part of the sulfur compound to be adsorbed and removed is removed by a silver-supported zeolite, and then the remaining sulfur compound is removed by another adsorbent (for example, a metal oxide). (See, for example, Patent Documents 2 and 3).
Furthermore, a multi-stage desulfurization method has been reported in which a part of the sulfur compound to be adsorbed and removed is removed by another adsorbent (for example, activated carbon impregnated with nickel), and then the remaining sulfur compound is removed by silver-supported zeolite. (See, for example, Patent Document 4).

Japanese Patent No. 4026700 Japanese Patent No. 4479589 Japanese Unexamined Patent Publication No. 2015-135789 Japanese Patent No. 3895134

By the way, various kinds of sulfur compounds are contained in the fuel gas. For example, methyl mercaptan (MM: methyl mercaptan), ethyl mercaptan (EM: ethyl mercaptan), and tert-butyl mercaptan (TBM: tertiary-butyl) are added to fuel gas for the purpose of detecting leakage. Mercaptans such as mercaptan), sulfides such as dimethyl sulfide (DMS: dimethyl sulfide), diethyl sulfide (DES: dimethyl sulfide), dimethyl disulfide (DMDS): dimethyl disulfide), and thiophenes such as tetrahydrothiophene (THT). Contains sulfur compounds such as.
Commonly added odorants are TBM, DMS, and THT. For example, in city gas, both TBM and DMS are often used. The concentration of these odorants contained in the fuel gas is about several ppm.
Note that in the city gas, as sulfur compounds other than odorant, hydrogen sulfide (H 2 _S), those derived from raw materials such as carbonyl sulfide (COS), be included such as those mixed while flowing through a conduit There is also.

When the sulfur compounds to be adsorbed are diverse, such as mercaptans, sulfides, thiophenes, etc., if all of these sulfur compounds are to be adsorbed and removed only by the silver-supported zeolite described in Patent Document 1, silver-supported A large amount of zeolite is required. Since the raw material of silver-supported zeolite is expensive, the desulfurization cost increases as the amount used increases.
On the other hand, in the multi-stage desulfurization method described in Patent Documents 2 to 4, by combining the silver-supported zeolite and another adsorbent, only the silver-supported zeolite described in Patent Document 1 is used. The amount of silver-supported zeolite used can be reduced as compared with the desulfurization method. However, when a plurality of types of sulfur compounds are contained in the fuel gas, the amount of silver-supported zeolite used cannot be reduced so much.

Considering that the spread of household fuel cell systems has become realistic in recent years, as a desulfurizer for fuel gas, it adsorbs a plurality of types of sulfur compounds contained in the fuel gas at a lower cost. It can be said that it is necessary that it can be removed and that it can be miniaturized.

The present invention has been made in view of the above circumstances, can efficiently adsorb and remove a plurality of types of sulfur compounds contained in a fuel gas, and desulfurize using a conventional silver-supported zeolite. It is an object of the present invention to provide a desulfurizer for fuel gas, which can reduce the amount of silver-supported zeolite used and can realize the miniaturization of the desulfurizer as compared with the vessel.

Specific means for solving the above problems include the following embodiments.
<1> A first desulfurization section including a first desulfurization agent and a second desulfurization section provided downstream of the first desulfurization section in the gas flow direction and having a second desulfurization agent are provided. The first desulfurizing agent contains activated charcoal and a metal adhered to the activated charcoal, the metal is a combination of copper and nickel, and the amount of the impregnated copper is the total amount of the first desulfurizing agent. It is in the range of 2.0% by mass to 8.0% by mass with respect to the mass, and the amount of nickel attached is 2.0% by mass to 8.0 with respect to the total mass of the first desulfurizing agent. The second desulfurizing agent is a desulfurizer for fuel gas containing nickel supported by silver, which is in the range of% by mass.
<2> The desulfurizer for fuel gas according to <1>, wherein the amount of nickel attached is in the range of 20% by mass to 80% by mass with respect to the total mass of the metal attached to the activated carbon.
<3> The desulfurizer for fuel gas according to <1> or <2>, wherein the ratio of the amount of nickel attached to the amount of copper attached is in the range of 0.30 to 2.70 on a mass basis.

According to the present invention, a plurality of types of sulfur compounds contained in a fuel gas can be efficiently adsorbed and removed, and the amount of silver-supported zeolite used is compared with that of a conventional desulfurizer using silver-supported zeolite. A desulfurizer for fuel gas is provided, which can reduce the amount of waste and can realize the miniaturization of the desulfurizer.

It is a schematic block diagram which shows the desulfurizer for fuel gas which concerns on this embodiment. It is the schematic of the desulfurizer used for the evaluation test of an Example. It is a graph which shows the structure of the desulfurizer designed based on the result of the evaluation test of an Example. It is the schematic of the experimental apparatus used for the evaluation test of an Example.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. can do.

The numerical range indicated by using "~" in the present specification means a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Good. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
In the present specification, the amount of each component in the desulfurizing agent is the total amount of the plurality of substances present in the desulfurizing agent unless otherwise specified, when a plurality of substances corresponding to each component are present in the desulfurizing agent. Means.

[Fuel gas desulfurizer]
The desulfurizer for fuel gas of the present invention has a first desulfurization section provided with a first desulfurization agent and a second desulfurization section provided with a second desulfurization agent, which is arranged downstream in the gas flow direction of the first desulfurization section. The first desulfurizing agent comprises, and the first desulfurizing agent comprises activated charcoal and a metal impregnated with the activated charcoal, wherein the metal is at least one selected from the group consisting of copper, nickel, tungsten, and molybdenum. , And the second desulfurizing agent is a desulfurizer containing silver-supported zeolite (silver-supported zeolite).
According to the desulfurizer for fuel gas of the present invention, a plurality of types of sulfur compounds contained in the fuel gas can be efficiently adsorbed and removed, and compared with a conventional desulfurizer using silver-supported zeolite, The amount of silver-supported zeolite used can be reduced, and the desulfurizer can be downsized.
The reason why the desulfurizer for fuel gas of the present invention can exert such an effect is not clear, but the present inventors speculate as follows.

The desulfurizer for fuel gas of the present invention has a first desulfurization section provided with a first desulfurization agent and a second desulfurization section provided with a second desulfurization agent, which is arranged downstream in the gas flow direction of the first desulfurization section. The fuel gas containing a sulfur compound supplied to the desulfurizer for fuel gas is provided with a second desulfurizing agent after being circulated in the first desulfurizing section provided with the first desulfurizing agent. Distribute the desulfurized part of 2.
The first desulfurization agent is a desulfurization agent in which copper and a specific metal (that is, at least one selected from the group consisting of nickel, tungsten, and molybdenum) are impregnated with activated carbon, and has excellent desulfurization performance. , Multiple types of sulfur compounds contained in the fuel gas can be efficiently adsorbed and removed. Therefore, the first desulfurizing agent is contained in the fuel gas in a smaller amount than, for example, as compared with the conventional desulfurizing agent in which only nickel is impregnated with the activated carbon described in Patent Document 4 (Patent No. 3895134). It is possible to adsorb and remove a plurality of types of sulfur compounds contained therein.
The first desulfurizing agent is particularly excellent in the ability to adsorb mercaptans (particularly TBM), which are the main sulfur compounds contained in city gas.

By the way, the fuel gas may contain thiophenes as sulfur compounds. Thiophenes may be oxidized on the desulfurizing agent to become thiophenes that are difficult to remove by adsorption. The first desulfurizing agent is a desulfurizing agent in which copper and a specific metal (that is, at least one selected from the group consisting of nickel, tungsten, and molybdenum) are impregnated with activated carbon in the fuel gas. Even when a sulfur compound capable of producing thiophene is contained in, thiophene is difficult to be produced.

For example, when the first desulfurizing agent is a desulfurizing agent in which copper and nickel are impregnated with activated carbon, the oxidizing power of copper is suppressed by nickel, and as a result, thiophene can be produced in the fuel gas. It is considered that the production of thiophene is suppressed even when the compound is contained.
Further, in the first desulfurizing agent, it is considered that most of the metal is attached to the activated carbon as a compound containing a metal element (oxide, inorganic acid salt, organic acid salt, etc., particularly oxide). When the first desulfurizing agent is a desulfurizing agent in which a combination of copper and tungsten or a combination of copper and molybdenum is impregnated with activated carbon, the oxide of tungsten and the oxide of molybdenum have many oxygen deficiencies. Therefore, it is considered that the production of thiophene is suppressed by adsorbing sulfur, which is a sulfur compound capable of producing thiophene, in the defective portion.

Examples of thiophenes that can produce thiophene by a reaction such as oxidation include thiophenes such as tetrahydrothiophene (THT), 2-methylthiophene, benzothiophene, dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene. Kind.

In addition, various types of sulfur compounds are contained in the fuel gas, and it is difficult to adsorb and remove them at the same time. Silver-supported zeolite is known to have an excellent ability to adsorb sulfur compounds, but a large amount is required to adsorb all of a plurality of types of sulfur compounds. Since the raw material of silver-supported zeolite is expensive, we want to reduce the amount used as much as possible.
In the desulfurizer for fuel gas of the present invention, as a desulfurizing agent (that is, the first desulfurizing agent) used in the first desulfurizing part through which the fuel gas first flows, copper and a specific metal are impregnated on the activated charcoal. By selecting the desulfurizing agent, the type and amount of the sulfur compound in the fuel gas flowing through the first desulfurizing part is reduced by the first desulfurizing agent. Therefore, in the second desulfurization section arranged downstream in the gas flow direction of the first desulfurization section, the amount of the second desulfurization agent required for adsorbing the sulfur compound, that is, the silver-supporting zeolite is reduced. Can be done. Moreover, in the first desulfurizing agent, the production of thiophene, which is difficult to remove by adsorption, is suppressed, so that it is not necessary to increase the amount of silver zeolite.

That is, in the hydrodesulfurizer for fuel gas of the present invention, as the desulfurizing agent, activated carbon in which copper and a specific metal are impregnated and silver-supported zeolite are selected, and the fuel gas is copper and a specific metal. By using a multi-stage desulfurization type desulfurizer in which silver-supported zeolite is circulated after being circulated in the activated coal impregnated with the metal, the amount of silver-supported zeolite used can be reduced, and the number of metals contained in the fuel gas can be reduced. Species of sulfur compounds can be efficiently adsorbed and removed. Further, since the activated carbon in which copper and a specific metal are impregnated is excellent in the adsorption performance of the sulfur compound, it is possible to adsorb and remove a plurality of types of sulfur compounds contained in the fuel gas with a relatively small amount. Therefore, in the desulfurizer for fuel gas of the present invention, the total amount of the desulfurizing agent used can be reduced. As a result, the desulfurizer can be miniaturized.

The desulfurizer for fuel gas of the present invention is excellent in that the sulfur concentration (so-called leaked sulfur concentration) leaking from the desulfurizing agent (that is, the first desulfurizing agent and the second desulfurizing agent) is 0.5 ppb or less. It can also have an effect.

Hereinafter, the desulfurizer for fuel gas of the present invention will be described in detail.

First, the desulfurizer for fuel gas according to this embodiment will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a fuel gas desulfurizer according to the present embodiment.
The fuel gas desulfurizer 1 according to the present embodiment is arranged downstream of the first desulfurization section 10 including the first desulfurization agent and the gas flow direction of the first desulfurization section 10, and includes a second desulfurization agent. A second desulfurization unit 20 is provided. The first desulfurization agent (not shown) included in the first desulfurization unit 10 contains activated carbon and a metal attached to the activated carbon, and the metals include copper, nickel, tungsten, and the like. And at least one selected from the group consisting of molybdenum. The second desulfurizing agent (not shown) included in the second desulfurizing unit 20 contains silver-supported zeolite (silver-supported zeolite).
In the fuel gas desulfurizer 1 according to the present embodiment, the fuel gas containing a sulfur compound flows in the direction of the arrow shown in FIG. That is, after the fuel gas containing the sulfur compound supplied to the desulfurizer 1 for fuel gas has passed through the first desulfurization unit 10 including the first desulfurization agent, the second desulfurization unit including the second desulfurization agent. By circulating 20, a plurality of types of sulfur compounds contained in the fuel gas are adsorbed and removed by the first desulfurizing agent and the second desulfurizing agent.

The fuel gas containing a sulfur compound supplied to the desulfurizer 1 for fuel gas first circulates in the first desulfurization section 10 provided with the first desulfurization agent. Since the first desulfurizing agent can efficiently adsorb a plurality of types of sulfur compounds contained in the fuel gas, it exhibits excellent adsorption ability with a relatively small amount of use. Most of the sulfur compounds in the fuel gas flowing through the first desulfurization section 10 including the first desulfurization agent are removed by the first desulfurization agent, and then the second desulfurization containing the second desulfurization agent. Distribute part 20. The second desulfurizing agent only needs to be able to remove sulfur compounds that cannot be completely adsorbed by the first desulfurizing agent, and since the amount of sulfur compounds (for example, thiophene) that can be produced by the first desulfurizing agent is small, the second desulfurizing agent is used. Desulfurizing agents do not require large amounts. As a result, a plurality of types of sulfur compounds contained in the fuel gas can be efficiently adsorbed and removed, and the amount of silver-supported zeolite used is reduced as compared with a conventional desulfurizer using silver-supported zeolite. At the same time, the desulfurizer can be miniaturized.

[First desulfurization section]
The first desulfurization section includes a first desulfurization agent.
In the first desulfurization section, most of the plurality of sulfur compounds contained in the fuel gas are removed by the first desulfurization agent.

<First desulfurizing agent>
The first desulfurizing agent comprises activated carbon and a metal attached to the activated carbon, the metal comprising a combination of copper and at least one selected from the group consisting of nickel, tungsten and molybdenum. ..
By having the above-mentioned structure, the first desulfurizing agent can efficiently adsorb and remove a plurality of types of sulfur compounds contained in the fuel gas.

(Activated carbon)
The first desulfurizing agent contains at least one type of activated carbon.
As the activated carbon, activated carbon usually used in the art can be used without particular limitation.

Examples of raw materials for activated carbon include coconut shells, coal (anthracite, bituminous coal, etc.), wood flour, peat charcoal, bamboo charcoal, and the like.
Among these, coconut shell is preferable as a raw material for activated carbon from the viewpoint of having a small average pore diameter and a small content of impurities.

The activated carbon is preferably activated carbon treated with an inorganic acid. When the activated carbon is treated with an inorganic acid, impurities are removed, the specific surface area is improved, and the surface of the activated carbon is made hydrophilic, so that the dispersity of the impregnated metal can be further improved.
Examples of the inorganic acid for treating activated carbon include hydrochloric acid, nitric acid, sulfuric acid and the like.

The shape of the activated carbon is not particularly limited, and examples thereof include granular, columnar (for example, columnar), fibrous, honeycomb, and crushed.
Among these, as the shape of the activated carbon, for example, from the viewpoint of cost, at least one shape selected from the group consisting of granular, columnar, and crushed is preferable, and fine powder having a high density is used. From the viewpoint of not containing, at least one shape selected from granular and columnar is more preferable.

When the shape of the activated carbon is granular, the average particle size of the activated carbon is, for example, from the viewpoint of preventing gas drift and the mesh spacing of the desulfurizing agent outflow prevention filter when the gas flow rate is 10 L (liter) / min or less. , 0.5 mm or more and 5.0 mm or less, and more preferably 1.0 mm or more and 3.0 mm or less.
In the present specification, the "average particle size" means a volume average particle size (Mv), and is a value measured by using a laser diffraction / scattering type particle size distribution measuring device.

^{The specific surface area of the activated carbon is preferably 600 m 2} / g or more, and more preferably 1300 m ² / g or more, for example, from the viewpoint of improving the dispersity of the impregnated metal.
In the present specification, the "specific surface area" is a value measured by the BET method.

The average pore diameter of the activated carbon is preferably 0.9 nm or more and 2.0 nm or less, and preferably 0.9 nm or more and 1.5 nm or less, from the viewpoint that the pore diameter matches the molecular diameter of the sulfur compound, for example. More preferred.
In the present specification, the "average pore diameter" is a value measured by the nitrogen gas adsorption method.

(metal)
The first desulfurizing agent contains a metal impregnated with the activated carbon described above, and the metal is at least selected from the group consisting of copper (Cu), nickel (Ni), tungsten (W), and molybdenum (Mo). Includes one and a combination of.
Most of the above metals attached to the activated carbon are considered to be contained as compounds containing metal elements (oxides, inorganic acid salts, organic acid salts, etc.), but may be contained as a simple substance of the metal. ..

The metal may include a combination of copper and at least one selected from the group consisting of nickel, tungsten, and molybdenum, and the metal to be combined with copper may be one kind alone or two kinds. The above combination may be used. The metal may be a combination of copper and nickel, a combination of copper and tungsten, or a combination of copper and molybdenum.
For example, from the viewpoint of more efficiently adsorbing and removing sulfur compounds contained in the fuel gas, the metal preferably contains a combination of copper and tungsten, or a combination of copper and molybdenum, and copper and tungsten. It is more preferable to include the combination of.
For example, when the fuel gas contains a sulfur compound capable of producing thiophene, it is preferable to include a combination of copper and nickel as the metal from the viewpoint of significantly suppressing the production of thiophene.
The metal may be a combination of copper, nickel and tungsten, a combination of copper, nickel and molybdenum, a combination of copper, tungsten and molybdenum, and copper. It may be a combination of nickel, tungsten and molybdenum.

The amount of copper attached is, for example, preferably 1.0% by mass or more and 20.0% by mass or less, and 2.0% by mass or more and 15.0% by mass or less, based on the total mass of the first desulfurizing agent. It is more preferable that it is 2.0% by mass or more and 8.0% by mass or less.
When the metal to be combined with copper is nickel, the amount of nickel attached is preferably, for example, 1.0% by mass or more and 20.0% by mass or less with respect to the total mass of the first desulfurizing agent. It is more preferably 0% by mass or more and 15.0% by mass or less, and further preferably 2.0% by mass or more and 8.0% by mass or less.
When the metal to be combined with copper is tungsten, the amount of tungsten attached is preferably, for example, 1.0% by mass or more and 20.0% by mass or less with respect to the total mass of the first desulfurizing agent. It is more preferably 0% by mass or more and 15.0% by mass or less, and further preferably 2.0% by mass or more and 8.0% by mass or less.
When the metal to be combined with copper is molybdenum, the amount of molybdenum attached is preferably, for example, 1.0% by mass or more and 20.0% by mass or less with respect to the total mass of the first desulfurizing agent. It is more preferably 0% by mass or more and 15.0% by mass or less, and further preferably 2.0% by mass or more and 8.0% by mass or less.

When the metal to be combined with copper is nickel, the ratio of the amount of nickel attached to the amount of copper attached (nickel attachment amount / copper attachment amount) shall be in the range of 0.20 to 2.70 on a mass basis. Is more preferable, the range is more preferably 0.25 to 2.50, further preferably the range is 0.30 to 2.00, and particularly preferably the range of 0.30 to 1.00. ..
When the ratio of the amount of nickel attached to the amount of copper attached is within the above range, the sulfur compound contained in the fuel gas can be more efficiently adsorbed and removed, and thiophene can be generated in the fuel gas. When a sulfur compound is contained, the production of thiophene can be further suppressed.

When the metal to be combined with copper is tungsten, the ratio of the amount of tungsten attached to the amount of copper attached (tungsten attachment amount / copper attachment amount) shall be in the range of 0.10 to 0.60 on a mass basis. Is preferable, and the range is more preferably 0.15 to 0.60.
When the ratio of the amount of tungsten attached to the amount of copper attached is within the above range, the sulfur compound contained in the fuel gas can be more efficiently adsorbed and removed, and thiophene can be generated in the fuel gas. When a sulfur compound is contained, the production of thiophene can be further suppressed.
From the viewpoint of more efficiently adsorbing and removing sulfur compounds contained in the fuel gas, the ratio of the amount of tungsten attached to the amount of copper attached (tungsten attachment amount / copper attachment amount) is 0 on a mass basis. More preferably, it is in the range of .15 to 0.55.
From the viewpoint of further suppressing the formation of thiophene, the ratio of the amount of tungsten attached to the amount of copper attached (tungsten attachment amount / copper attachment amount) is in the range of 0.25 to 0.60 on a mass basis. Is more preferable.

When the metal to be combined with copper is molybdenum, the ratio of the amount of molybdenum attached to the amount of copper attached (molybdenum attachment amount / copper attachment amount) shall be in the range of 0.15 to 2.00 on a mass basis. Is preferable, and the range is more preferably 0.15 to 1.80.
When the ratio of the amount of molybdenum attached to the amount of copper attached is within the above range, the sulfur compound contained in the fuel gas can be more efficiently adsorbed and removed, and thiophene can be generated in the fuel gas. When a sulfur compound is contained, the production of thiophene can be further suppressed.
From the viewpoint of more efficiently adsorbing and removing sulfur compounds contained in the fuel gas, the ratio of the amount of molybdenum attached to the amount of copper attached (molybdenum attachment amount / copper attachment amount) is 0 on a mass basis. More preferably, it is in the range of .15 to 1.60.
From the viewpoint of further suppressing the formation of thiophene, the ratio of the amount of molybdenum attached to the amount of copper attached (molybdenum attachment amount / copper attachment amount) is in the range of 0.20 to 1.60 on a mass basis. Is more preferable, and the range of 0.30 to 1.60 is particularly preferable.

When the metal attached to the activated carbon contains copper and nickel, the amount of copper attached is preferably, for example, 20% by mass or more and 80% by mass or less with respect to the total mass of the metal attached to the activated carbon. It is more preferably mass% or more and 80% by mass or less, further preferably 40% by mass or more and 80% by mass or less, and particularly preferably 40% by mass or more and 65% by mass or less.
Further, the amount of nickel attached is preferably, for example, 20% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 70% by mass or less, based on the total mass of the metal attached to the activated carbon. It is more preferably 20% by mass or more and 60% by mass or less, and particularly preferably 35% by mass or more and 60% by mass or less.

When the metal attached to the activated carbon contains copper and tungsten, the amount of copper attached is preferably, for example, 50% by mass or more and 85% by mass or less with respect to the total mass of the metal attached to the activated carbon. More preferably, it is by mass% or more and 75% by mass or less.
Further, the amount of tungsten attached is preferably, for example, 15% by mass or more and 50% by mass or less, and more preferably 25% by mass or more and 50% by mass or less, based on the total mass of the metal attached to the activated carbon. preferable.

When the metal attached to the activated carbon contains copper and molybdenum, the amount of copper attached is preferably, for example, 30% by mass or more and 85% by mass or less with respect to the total mass of the metal attached to the activated carbon. More preferably, it is by mass% or more and 85% by mass or less.
Further, the amount of molybdenum attached is preferably, for example, 15% by mass or more and 70% by mass or less, and more preferably 15% by mass or more and 65% by mass or less, based on the total mass of the metal attached to the activated carbon. preferable.

In the present specification, the amount of metal attached to the activated carbon (that is, the amount of attachment) is a value measured by ICP (Inductively Coupled Plasma) emission spectroscopy. As the measuring device, for example, Optima 8000 (product name) manufactured by Perkin-Elmer can be preferably used. However, the measuring device is not limited to this.

(Other ingredients)
The first desulfurizing agent contains, if necessary, activated carbon, copper, and other components other than at least one selected from the group consisting of nickel, tungsten, and molybdenum, as long as the effects of the present invention are not impaired. But it may be.
The first desulfurizing agent may contain a metal other than copper, nickel, tungsten, and molybdenum as an unavoidable component as long as the effects of the present invention are not impaired.

~ Shape of the first desulfurizing agent ~
The shape of the first desulfurizing agent is not particularly limited and can be appropriately selected depending on the intended purpose.
Examples of the shape of the first desulfurizing agent include granular, columnar (for example, columnar), fibrous, honeycomb, and crushed shapes.
Among these, as the shape of the first desulfurizing agent, for example, from the viewpoint of cost, at least one shape selected from the group consisting of granular, columnar, and crushed is preferable, and the shape has high density and From the viewpoint of not containing fine powder, at least one shape selected from granular and columnar is more preferable.

-Manufacturing method of the first desulfurizing agent-
The method for producing the first desulfurizing agent is not particularly limited, and a known method can be adopted as a method for adhering a metal to activated carbon to produce the first desulfurizing agent.

An example of the method for producing the first desulfurizing agent will be described. The first desulfurizing agent can be produced, for example, by the following method. However, the method for producing the first desulfurizing agent is not limited to this.
(1) A solution (impregnation solution) in which a metal compound containing a metal element to be impregnated with activated carbon is dissolved or dispersed in a solvent is prepared.
(2) The activated carbon is immersed in the impregnated solution.
(3) The activated carbon immersed in the impregnated solution is dried to remove the solvent.
(4) The dried activated carbon after immersion is calcined to form a metal oxide or the like on the activated carbon to obtain a metal-impregnated carbon (first desulfurizing agent).
By the above method, the first desulfurizing agent can be produced.

Examples of the metal compound for preparing the impregnating solution include metal salts such as metal nitrate, metal acetate, metal sulfate, metal chloride and metal phosphate.
Specifically, copper nitrate trihydrate, copper acetate monohydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate, 12-tangstrate n hydrate, ammonium molybdate tetrahydrate. And so on.

The solvent for preparing the impregnation solution is not particularly limited, and is limited to water, an acidic aqueous solution (nitrite aqueous solution, etc.), a basic aqueous solution (ammonia aqueous solution, etc.), an alcohol solvent (methanol, ethanol, n-propanol, etc.), and a ketone. Examples thereof include based solvents (acetone, methyl ethyl ketone, etc.), ether solvents (diethyl ether, etc.), ester solvents (ethyl acetate, butyl acetate, etc.), hydrocarbon solvents (toluene, etc.) and the like.
Among these, water is preferable as the solvent for preparing the impregnating solution from the viewpoint that it does not remain after firing.
In the preparation of the impregnation solution, one type of solvent may be used alone, or two or more types may be mixed and used.

The concentration of the metal compound in the impregnating solution is not particularly limited, and can be appropriately set depending on, for example, the type of the metal compound, the amount of the metal attached to the activated carbon, the type of the activated carbon, and the like.

The immersion temperature is not particularly limited and can be, for example, in the range of 10 ° C to 80 ° C.
The immersion time is also not particularly limited, and can be, for example, in the range of 5 minutes to 2 hours.

The drying method is not particularly limited, and examples thereof include a method of drying by heating.
The heating temperature is not particularly limited and can be, for example, in the range of 50 ° C. to 150 ° C.

The firing temperature is preferably in the range of 150 ° C. to 300 ° C. from the viewpoint of promoting the decomposition of the metal compound and suppressing the ignition of the metal-impregnated coal, for example.
The firing time is not particularly limited, and can be, for example, in the range of 1 hour to 24 hours.

[Second desulfurization section]
The second desulfurization section is arranged downstream in the gas flow direction of the first desulfurization section described above, and includes a second desulfurization agent.
In the second desulfurization section, the sulfur compound that cannot be completely adsorbed by the first desulfurization agent and the sulfur compound (for example, thiophene) that can be produced by the first desulfurization agent are adsorbed and removed by the second desulfurization agent.
Since the type and amount of the sulfur compound in the fuel gas flowing through the first desulfurization section is reduced by the first desulfurization agent, the second desulfurization agent does not require a large amount to be used.

<Second desulfurization agent>
The second desulfurizing agent contains silver-supported zeolite (silver-supported zeolite).
Since the second desulfurizing agent contains silver-supported zeolite, it is possible to adsorb and remove sulfur compounds that cannot be completely adsorbed by the first desulfurizing agent and sulfur compounds (for example, thiophene) that can be produced by the first desulfurizing agent. it can.

(Silver-supported zeolite)
Silver zeolite is a zeolite on which silver (Ag) is supported, and can efficiently adsorb and remove a plurality of types of sulfur compounds contained in the fuel gas regardless of the water concentration in the fuel gas.
The zeolite is not particularly limited, and examples thereof include X-type zeolite, Y-type zeolite, and β-type zeolite.
Among these, as the zeolite, for example, a Y-type zeolite is preferable from the viewpoint of desulfurization performance, and a β-type zeolite is particularly preferable when the water concentration is high.

The amount of silver supported is preferably 3% by mass or more with respect to the mass of zeolite, for example, from the viewpoint of desulfurization performance.
The upper limit of the amount of silver carried is not particularly limited, and can be, for example, 20% by mass or less.

(Other ingredients)
The second desulfurizing agent may contain zeolite and other components other than silver, if necessary, as long as the effects of the present invention are not impaired.
Other components include a binder as a molding material. Examples of the binder include alumina, silica, clay minerals and the like.
The second desulfurizing agent may contain a metal other than silver as an unavoidable component as long as the effects of the present invention are not impaired.

~ Shape of the second desulfurizing agent ~
The shape of the second desulfurizing agent is not particularly limited and can be appropriately selected depending on the intended purpose.
Examples of the shape of the second desulfurizing agent include a granular shape, a columnar shape (for example, a columnar shape), a honeycomb shape, and a crushed shape.
Among these, as the shape of the second desulfurizing agent, for example, from the viewpoint of cost, at least one shape selected from the group consisting of granular, columnar, and crushed is preferable, and the shape has high density and From the viewpoint of not containing fine powder, at least one shape selected from granular and columnar is more preferable.

-Manufacturing method of the second desulfurizing agent-
The method for producing the second desulfurizing agent is not particularly limited, and a known method can be adopted as a method for supporting silver on zeolite, and the second desulfurizing agent can be produced. Examples of the method for supporting silver on zeolite include an ion exchange method.

As the second desulfurizing agent, a commercially available product can be used. As an example of a commercially available second desulfurizing agent, FKS-A (trade name, shape: granular, type of zeolite: Y-type zeolite, silver carrying amount: 14% by mass with respect to the mass of zeolite, JGC Catalysts and Chemicals). Co., Ltd.).

[Use of desulfurizer for fuel gas]
The desulfurizer for fuel gas of the present invention is a desulfurizer applied for the purpose of removing sulfur compounds contained in fuel gas used as fuel, and for example, sulfur compounds can be used in a temperature range of 0 ° C to 60 ° C. A desulfurizer used for so-called room temperature adsorption desulfurization method, which removes sulfur compounds in the fuel gas by contacting them with the containing fuel gas and physically or chemically adsorbing the sulfur compounds on the surface of the desulfurization agent. is there.

Examples of the fuel gas containing a sulfur compound include city gas, LP gas, natural gas, digestion gas, exhaust gas and the like. The desulfurizer for fuel gas of the present invention can be applied to any of these fuel gases.

Fuel gas desulfurizer of the present invention, the fuel gas hydrogen sulfide _(H 2 S) contained in, carbonyl sulfide (COS), mercaptans [methyl mercaptan (MM), ethyl mercaptan (EM), tert-butyl mercaptan ( TBM), etc.], sulfides [dimethyl sulfide (DMS), diethyl sulfide (DES), dimethyl disulfide (DMDS), etc.], thiophenes [tetrahydrothiophene (THT), etc.] and various sulfur compounds are efficiently adsorbed and removed. As compared with the conventional desulfurizer using silver-supported zeolite, the amount of silver-supported zeolite used can be reduced and the desulfurizer can be miniaturized. Therefore, for example. It is suitable as a desulfurizer in the pretreatment stage (that is, a room temperature adsorption desulfurizer) in a fuel cell system using fuel gas such as city gas, LP gas, natural gas, digestion gas, and exhaust gas.
Since the desulfurizer for fuel gas of the present invention can reduce the amount of silver-supported zeolite used, it can be used as a desulfurizer in a household fuel cell system, which is particularly required to reduce the cost and size of the desulfurizer. , Suitable for use.

[Manufacturing method of desulfurizer for fuel gas]
The desulfurizer for fuel gas of the present invention can be produced, for example, by filling a predetermined container with a first desulfurizing agent and a second desulfurizing agent in order.
Examples of the material of the container include stainless steel (SUS) and resin.
Examples of the shape of the container include a cylindrical shape and a square tubular shape.
The filling densities of the first desulfurizing agent and the second desulfurizing agent in the container can be appropriately set in consideration of the adsorption amount of the sulfur compound contained in the fuel gas, the pressure loss, and the like.

The desulfurizer for fuel gas of the present invention may be provided with a filter or the like for preventing the second desulfurizing agent from scattering on the downstream side in the gas flow direction of the container.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.
In this embodiment, in order to determine the breakthrough time at an early stage, the test is performed under the condition that the concentration and the flow rate at the time of the test are accelerated, and the test conditions are different from the actual use conditions.

In the following examples, a tert- butyl mercaptan represented by "TBM", dimethyl sulfide is referred to as "DMS", denoted hydrogen sulfide and "H _{2 S",} denoted methyl mercaptan and "MM", Dimethyl disulfide is referred to as "DMDS", tetrahydrothiophene is referred to as "THT", and carbonyl sulfide is referred to as "COS".

[Manufacturing of first desulfurizing agent]
[Manufacturing Example 1]
19 parts by mass of copper nitrate trihydrate and 25 parts by mass of nickel nitrate hexahydrate were dissolved in 500 parts by mass of water to obtain an impregnated solution. The resulting impregnation solution, coconut shell activated carbon treated with an inorganic acid (trade name: particulate Shirasagi _{C 2X,} shape: cylindrical, specific surface ^{area: 1200m 2 / g~1500m 2 / g} , manufactured by Osaka Gas Chemicals Co.) 100 parts by mass was immersed for 5 minutes. The soaked coconut shell activated carbon was placed in a flask provided in a rotary evaporator (model number: N1110 type, manufactured by Tokyo Rika Kikai Co., Ltd.). The soaked coconut shell activated carbon was dried under reduced pressure at 50 ° C. for 120 minutes without sudden boiling while rotating the flask and stirring. The soaked coconut shell activated carbon that has been dried is taken out from the flask, placed in a hot air circulation dryer (model number: FS-60W, manufactured by Tokyo Glass Instruments Co., Ltd.), and fired at a firing temperature of 150 ° C. for 15 hours under air circulation. , A metal-impregnated carbon (that is, a desiccant) in which copper and nickel were impregnated with the coconut shell activated carbon was obtained. The obtained metal-impregnated charcoal was crushed using an agate mortar and then sieved through a sieve having a mesh size of 0.35 μm to 0.75 μm to obtain a first desulfurizing agent A.
The amount of copper and nickel attached to the first desulfurizing agent A was measured by ICP emission spectroscopic analysis using Optima 8000 (product name) manufactured by Perkin-Elmer. As a result, the total mass of the first desulfurizing agent A was measured. It was 3.3% by mass and 3.1% by mass, respectively. The ratio of the amount of nickel attached to the amount of copper attached in the first desulfurizing agent A (nickel attachment amount / copper attachment amount) is 0.94 on a mass basis.

[Manufacturing Example 2]
A coconut palm was obtained in the same manner as in Production Example 1 except that an impregnated solution was obtained by dissolving 38 parts by mass of copper nitrate trihydrate and 25 parts by mass of nickel nitrate hexahydrate in 500 parts by mass of water. A metal-imposed coal (that is, a desulfurizing agent) in which copper and nickel were impregnated with the shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain a first desulfurizing agent B.
The amount of copper and nickel attached to the first desulfurizing agent B was measured by the same method as that of the first desulfurizing agent A, and found to be 6.9 masses with respect to the total mass of the first desulfurizing agent B. % And 2.8% by mass. The ratio of the amount of nickel attached to the amount of copper attached in the first desulfurizing agent B (nickel attachment amount / copper attachment amount) is 0.41 on a mass basis.

[Manufacturing Example 3]
A palm was obtained in the same manner as in Production Example 1 except that an impregnated solution was obtained by dissolving 19 parts by mass of copper nitrate trihydrate and 50 parts by mass of nickel nitrate hexahydrate in 500 parts by mass of water. A metal-imposed coal (that is, a desulfurizing agent) in which copper and nickel were impregnated with the shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain the first desulfurizing agent C.
When the amount of copper and nickel attached to the first desulfurizing agent C was measured by the same method as that of the first desulfurizing agent A, it was 2.7 masses with respect to the total mass of the first desulfurizing agent C. % And 5.5% by mass. The ratio of the amount of nickel attached to the amount of copper attached in the first desulfurizing agent C (nickel attachment amount / copper attachment amount) is 2.04 on a mass basis.

[Manufacturing Example 4]
A palm was obtained in the same manner as in Production Example 1 except that an impregnated solution was obtained by dissolving 19 parts by mass of copper nitrate trihydrate and 43 parts by mass of nickel nitrate hexahydrate in 500 parts by mass of water. A metal-imposed coal (that is, a desulfurizing agent) in which copper and nickel were impregnated with the shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain the first desulfurizing agent D.
The amount of copper and nickel attached to the first desulfurizing agent D was measured by the same method as that of the first desulfurizing agent A, and found to be 2.8 masses with respect to the total mass of the first desulfurizing agent D. % And 7.3% by mass. The ratio of the amount of nickel attached to the amount of copper attached in the first desulfurizing agent D (nickel attachment amount / copper attachment amount) is 2.61 on a mass basis.

[Manufacturing Example 5]
Production Example 1 except that an impregnated solution was obtained by dissolving 38 parts by mass of copper nitrate trihydrate and 7.5 parts by mass of 12-tangstronic acid n-hydrate in 500 parts by mass of water. Similarly, a metal-imposed coal (that is, a desulfurizing agent) in which copper and tungsten were impregnated with the coconut shell activated carbon was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain a first desulfurizing agent E.
When the amount of copper and tungsten attached to the first desulfurizing agent E was measured by the same method as that of the first desulfurizing agent A, it was 7.1 masses with respect to the total mass of the first desulfurizing agent E, respectively. % And 1.4% by mass. The ratio of the amount of tungsten attached to the amount of copper attached in the first desulfurizing agent E (the amount of tungsten attached / the amount of copper attached) is 0.20 on a mass basis.

[Manufacturing Example 6]
The same as in Production Example 1 except that 38 parts by mass of copper nitrate trihydrate and 16 parts by mass of 12-tangstophosphate n hydrate were dissolved in 500 parts by mass of water to obtain an impregnated solution. Then, a metal-imposed coal (that is, a desulfurizing agent) in which copper and tungsten were impregnated with the coconut shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain the first desulfurizing agent F.
The amount of copper and tungsten attached to the first desulfurizing agent F was measured by the same method as that of the first desulfurizing agent A, and found to be 6.8 masses with respect to the total mass of the first desulfurizing agent F. % And 4.0% by mass. The ratio of the amount of tungsten attached to the amount of copper attached in the first desulfurizing agent F (tungsten attachment amount / copper attachment amount) is 0.59 on a mass basis.

[Manufacturing Example 7]
The same as in Production Example 1 except that an impregnated solution was obtained by dissolving 38 parts by mass of copper nitrate trihydrate and 9.4 parts by mass of ammonium molybdate tetrahydrate in 500 parts by mass of water. Then, a metal-imposed coal (that is, a desulfurizing agent) in which copper and molybdenum were impregnated with the coconut shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain the first desulfurizing agent G.
When the amount of copper and molybdenum attached to the first desulfurizing agent G was measured by the same method as that of the first desulfurizing agent A, it was 7.8 masses with respect to the total mass of the first desulfurizing agent G. % And 2.0% by mass. The ratio of the amount of molybdenum attached to the amount of copper attached in the first desulfurizing agent G (molybdenum attachment amount / copper attachment amount) was 0.26 on a mass basis.

[Manufacturing Example 8]
The same as in Production Example 1 except that an impregnated solution was obtained by dissolving 19 parts by mass of copper nitrate trihydrate and 9.4 parts by mass of ammonium molybdate tetrahydrate in 500 parts by mass of water. Then, a metal-imposed coal (that is, a desulfurizing agent) in which copper and molybdenum were impregnated with the coconut shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain the first desulfurizing agent H.
The amount of copper and molybdenum attached to the first desulfurizing agent H was measured by the same method as that of the first desulfurizing agent A, and found to be 3.9 masses with respect to the total mass of the first desulfurizing agent H. % And 2.2% by mass. The ratio of the amount of molybdenum attached to the amount of copper attached to the first desulfurizing agent H (molybdenum attachment amount / copper attachment amount) was 0.56 on a mass basis.

[Manufacturing Example 9]
In the same manner as in Production Example 1, 19 parts by mass of copper nitrate trihydrate and 19 parts by mass of ammonium molybdate tetrahydrate were dissolved in 500 parts by mass of water to obtain an impregnated solution. A metal-impregnated coal (that is, a desulfurizing agent) in which copper and molybdenum were impregnated with coconut shell activated charcoal was obtained. The obtained metal-impregnated coal was crushed and sized in the same manner as in Production Example 1 to obtain the first desulfurizing agent I.
When the amount of copper and molybdenum attached to the first desulfurizing agent I was measured by the same method as that of the first desulfurizing agent A, it was found to be 3.4 masses with respect to the total mass of the first desulfurizing agent I. % And 5.2% by mass. The ratio of the amount of molybdenum attached to the amount of copper attached in the first desulfurizing agent I (molybdenum attachment amount / copper attachment amount) was 1.53 on a mass basis.

[Performance evaluation of the first desulfurizing agent]
-Preparation of desulfurizer for evaluation test-
Using the first desulfurizing agents A to I obtained above, a desulfurizer for evaluation test was prepared. As shown in FIG. 2, the cylindrical tube 100 (inner diameter: 8.0 mm) was filled with the desulfurizing agent 200 so that the packed layer height was 38 mm. The filling amount of the desulfurizing agent is about 2 cm ³ . The cylindrical tube 100 has a perforated plate 300 at the outlet portion.
For comparison, commercially available activated carbon for desulfurization [trade name: Granular Shirasagi NCC, coconut shell activated carbon treated with inorganic acid with nickel attached (nickel attachment amount: total mass of coconut shell activated carbon treated with inorganic acid) relative, 10% to 20% by weight), shape: crushed shape, specific surface ^{area: 900m 2 / g~1100m 2 / g} , with Osaka gas Chemicals Co., Ltd.], in the same manner as described above, evaluation test A desulfurizer for use was prepared.

-Measurement of adsorption amount of sulfur compounds-
The desulfurizer for evaluation test prepared above was placed in a constant temperature bath, and the inside of the tank was kept warm at 60 ° C. Then, a test gas prepared by adding a sulfur compound having the composition shown in Table 1 below to the desulfurized city gas 13A was flowed into the desulfurizer for evaluation test at a flow rate of 1.0 L / min. The dew point temperature of the test gas is −60 ° C. The test gas flows in the direction of the arrow shown in FIG.

The test gas was flowed until a breakthrough point (breakthrough standard: 28.6 mg / m ^{3) of all sulfur compounds was confirmed.} Then, the amount of each sulfur compound adsorbed on the desulfurizing agent is calculated from the time from when the test gas is passed until the break point of each sulfur compound is confirmed, the flow rate of the test gas, and the composition of the test gas. did.
The breakthrough point of the sulfur compound was confirmed by collecting the gas discharged from the outlet of the desulfurizer for evaluation test every 3 hours and detecting the peak attributed to each sulfur compound by using gas chromatography. ..
The measurement conditions for gas chromatography are as follows.

(Measurement condition)
Gas chromatography system: GC-2014A (model number) manufactured by Shimadzu Access Co., Ltd.
Detector: Hydrogen flame ionization detector Analytical column: Shimalite 80/100 AW-AMDS-ST (trade name: 4.1 m x 3.2 mm ID, manufactured by Shinwa Kako Co., Ltd.)
Injection amount: 3 mL
Column temperature: 170 ° C

As a representative, the measurement results of the adsorption amounts of TBM, THT, and DMDS are shown in Table 2 below.
The higher the value of the total adsorption amount of the three types of TBM, THT, and DMDS, the more excellent the desulfurizing agent has in adsorbing the sulfur compound.

-Measurement of thiophene production concentration-
In the measurement of the adsorption amount of the sulfur compound described above, the thiophene concentration in the gas collected from the outlet of the desulfurizer for evaluation test every 3 hours until the breakthrough point of TBM or MM is confirmed is determined by the TBM or MM. The thiophene production concentration was converted into the average concentration of the time to the earlier of the breakthrough points.
The concentration of thiophene produced was measured by the absolute calibration curve method by gas chromatography. The measurement conditions for gas chromatography are the same as the measurement conditions for measuring the adsorption amount of the sulfur compound described above. The calibration curve was prepared using standard thiophene under the above-mentioned measurement conditions of gas chromatography.
The measurement results of the thiophene production concentration are shown in Table 2 below.

In Table 2, the first desulfurizing agent A is referred to as "A". Similarly, the first desulfurizing agents B to I are also referred to as "B" to "I", respectively.
In Table 2, granular Shirasagi NCC, which is a commercially available activated carbon for desulfurization, is referred to as “NCC”.
In Table 2, the value of "adsorption amount" is the value obtained by dividing the amount of the sulfur compound adsorbed on the first desulfurizing agent up to the breakthrough point by the mass of the first desulfurizing agent before adsorption. The value (unit: mass% S) converted into sulfur element is shown.
In Table 2, the ratio (mass basis) of the amount of nickel, tungsten, or molybdenum attached to the amount of copper attached in the first desulfurizing agent is referred to as "adhesion ratio (Ni, W, Mo / Cu)".

[Design of desulfurizer]
-Setting the amount of the first desulfurizing agent-
The amount of the first desulfurizing agent was set based on the result of the adsorption amount of TBM shown in Table 2.
More specifically, the desulfurized city gas ^{13A, 7.0mg / m 3 ~14.0mg /} m 3 of ^{TBM, 0.7mg / m 3 ~2.8mg /} m 3 of THT, and 1.4 mg / When the test gas to which DMDS of ^{m 3 to} 7.0 mg / m ^{3 is added is flowed so that the amount of flowing gas is 5000 m 3} , all of the TBM contained in the test gas can be adsorbed. The amount of the desulfurizing agent in 1 was calculated according to the following formula (1) based on the result of the adsorbed amount of TBM shown in Table 2.
Amount of first desulfurizing agent [cm ³ ] = concentration of TBM in test gas [mg / m ³ ] × amount of flowing gas of test gas [m ³ ] ÷ (adsorption amount of TBM shown in Table 2 [mass] % S] / 100) ÷ 1000 ÷ specific gravity of the first desulfurizing agent [g / cm ³ ] ... Equation (1)

With the amount of the first desulfurizing agent set above, the amount of THT and DMDS that cannot be completely adsorbed, and the amount of thiophene produced are determined according to the following formulas (2), (3), and (4), respectively. , Calculated. In the following formulas (2), (3), and (4), the amount [cm ³ ] of the first desulfurizing agent calculated above was converted into g (gram) units and used. .. The conversion formula is shown in formula (1A).
Amount of first desulfurizing agent [g] = amount of first desulfurizing agent [cm ³ ] × specific gravity of first desulfurizing agent [g / cm ³ ] ... Equation (1A)
Amount of THT [mg] = Concentration of THT in test gas [mg / m ³ ] x Amount of flowing gas of test gas [m ³ ] -Amount of first desulfurizing agent [g] x 1000 x (Table 2) Amount of THT adsorbed [mass% S] / 100) ... Equation (2)
Amount of DMDS [mg] = Concentration of DMDS in test gas [mg / m ³ ] x Amount of circulating gas in test gas [m ³ ] -Amount of first desulfurizing agent [g] x 1000 x (Table 2) DMDS adsorption amount [mass% S] / 100) ... Equation (3)
Amount of thiophene produced [mg] = Concentration of thiophene produced shown in Table 2 [mg / m ³ ] x Amount of circulating gas of test gas [m ³ ] -Amount of first desulfurizing agent [g] x 1000 x (Table) Adsorption amount of thiophene shown in 2 [mass% S] / 100) ... Equation (4)

-Setting the amount of the second desulfurizing agent-
As the second desulfurizing agent, a commercially available silver-supported zeolite (trade name: FKS-A, shape: granular, type of zeolite: Y-type zeolite, silver-supported amount: 14% by mass based on the mass of zeolite, JGC Catalysts and Chemicals). A desulfurizer for evaluation test was prepared using (Co., Ltd.). As shown in FIG. 2, the cylindrical tube 100 (inner diameter: 8.0 mm) was filled with the desulfurizing agent 200 so that the packed layer height was 38 mm. The filling amount of the desulfurizing agent is about 2 cm ³ . The cylindrical tube 100 has a perforated plate 300 at the outlet portion.
The desulfurizer for evaluation test prepared above was placed in a constant temperature bath, and the inside of the tank was kept warm at 60 ° C. Then, in the desulfurizer for evaluation test, 0.7 mg / m ^{3 to} 2.8 mg / m ³ of THT and 1.4 mg / m ^{3 to} 7.0 mg / m ³ of DMDS were added to the desulfurized city gas 13A. and 0.05mg ^{/ m 3} ~0.50mg ^/ m 3 thiophene test gas added was flowed at a flow rate of 1.0 L / min. The dew point temperature of the test gas is −60 ° C. The test gas flows in the direction of the arrow shown in FIG.

For all sulfur compounds, run the test gas until a break point (THT and DMDS break criteria: 28.6 mg / m ³ , thiophene break criteria: 28.6 mg / m ^{3) is confirmed.} did. Then, based on the time from the flow of the test gas to the confirmation of the breakthrough point of each sulfur compound, the flow rate of the test gas, and the composition of the test gas, the adsorption of each sulfur compound on the second desulfurizing agent. The amount was calculated.
The breakthrough point of the sulfur compound was confirmed by collecting the gas discharged from the outlet of the desulfurizer for evaluation test every 3 hours and detecting the peak attributed to each sulfur compound by using gas chromatography. .. The measurement conditions for gas chromatography are the same as the measurement conditions for measuring the adsorption amount of the sulfur compound described above.
The measurement results of the adsorption amounts of THT, DMDS, and thiophene in the second desulfurizing agent are shown in Table 3 below.

In Table 3, the value of "adsorption amount" is obtained by dividing the amount of the sulfur compound adsorbed on the second desulfurizing agent by the breaking point by the mass of the desulfurizing agent before adsorption, and converting the obtained value into the sulfur element. The converted value (unit: mass% S) is shown.

It was set based on the result of the adsorption amount of THT, DMDS, and thiophene in the second desulfurizing agent shown in Table 3 and the result of the adsorption amount of TBM in the first desulfurizing agent shown in Table 2 calculated above. The amount of the second desulfurizing agent was set based on the amount of THT and DMDS that could not be completely adsorbed by the first desulfurizing agent and the amount of thiophene produced. Specifically, it was set as follows.
First, the amounts of THT and DMDS that cannot be completely adsorbed by the amount of the first desulfurizing agent set above, and the amount of the second desulfurizing agent required for adsorbing the thiophene produced are determined by the following formulas (5) and formulas, respectively. It was calculated according to (6) and the formula (7).
Amount of second desulfurizing agent required for adsorption of THT [cm ³ ] = Amount of THT calculated by the formula (2) [mg] ÷ (Adsorption amount of THT [mass% S] / 100 shown in Table 3) ÷ 1000 ÷ Specific gravity of the second desulfurizing agent [g / cm ³ ] ・ ・ ・ Equation (5)
Amount of second desulfurizing agent required for adsorption of DMDS [cm ³ ] = amount of DMDS calculated by equation (2) [mg] ÷ (adsorption amount of DMDS shown in Table 3 [mass% S] / 100) ÷ 1000 ÷ Specific gravity of the second desulfurizing agent [g / cm ³ ] ・ ・ ・ Equation (6)
Amount of second desulfurizing agent required for thiophene adsorption [cm ³ ] = Amount of thiophene calculated by equation (2) [mg] ÷ (Amount of thiophene adsorbed [mass% S] / 100 shown in Table 3) ÷ 1000 ÷ Specific gravity of the second desulfurizing agent [g / cm ³ ] ・ ・ ・ Equation (7)

Of the amounts of the second desulfurizing agent calculated by the formulas (5), (6), and (7), the largest amount was set as the amount of the second desulfurizing agent.
The amount of the second desulfurizing agent set in this way is the THT and DMDS that cannot be completely adsorbed by the first desulfurizing agent when thiophene is produced by the first desulfurizing agent, and the first desulfurizing agent. It is an amount capable of adsorbing all of the produced thiophene, and when thiophene is not produced by the first desulfurizing agent, all of THT and DMDS that cannot be completely adsorbed by the first desulfurizing agent can be adsorbed. The amount.

The configurations of the desulfurizer designed based on the above results are shown in Tables 4 and 5 below.

As shown in Table 5 and FIG. 3, the desulfurizers of Examples 1 to 9 have a lower amount of silver-supported zeolite as the second desulfurizing agent as compared with the desulfurizer of Comparative Example 1. Was done.
Further, in the desulfurizers of Examples 1 to 9, the amount of the desulfurizing agent in the entire desulfurizer could be set lower than that of the desulfurizer of Comparative Example 1.
From these results, according to the present invention, the amount of expensive silver-supported zeolite used can be reduced, and the amount of desulfurizing agent used as a whole can be reduced. Therefore, the cost and size of the desulfurizer can be reduced. Is considered to be possible.

<Evaluation of leak sulfur amount>
An evaluation test of the amount of leaked sulfur was carried out using an experimental device as shown in FIG.
The experimental apparatus shown in FIG. 4 includes the desulfurizer 1 of Example 1 and the reformer 400 (reformer catalyst: ruthenium-supported catalyst, reformer temperature: 450 ° C. (upper part) arranged downstream in the gas flow direction of the desulfurizer 1). ), 680 ° C (lower part)).
City gas 13A was flowed into the desulfurizer 1 at a flow rate of 1.0 L / min, and water was flowed at a flow rate of ^{2.6 cm 3 / min in front of the reformer 400.} City gas 13A and water flow in the direction of the arrow shown in FIG. After flowing city gas 13A into the desulfurizer 1 for 3000 hours, the amount of sulfur leaked from the desulfurizer 1 was measured by quantifying the sulfur content adhering to the reforming catalyst in the reformer 400.
Sulfur content adhering to the reforming catalyst is carbon / sulfur analyzer (product name: EMIA-920V2, measurement method: combustion in oxygen stream (high frequency heating furnace method) -infrared absorption method, lower limit of quantification: 0.002% by mass, Measured using HORIBA).
As a result, the amount of leaked sulfur obtained from the amount of circulating gas of the city gas 13A and the total amount of sulfur in the city gas 13A was 0.32 ppb, and the amount of leaked sulfur in a conventional general desulfurizer (about several ppb, For example, it is very small compared to Reference Material 1 (see "European Expansion of Fuel Cell Units" by Hiroshi Tatsui et al., Panasonic Technical Journal Vol. 60, No. 2, Nov. 2014, p72, Table 1). It became clear.

1 ... Desulfurizer, 10 ... 1st desulfurization part, 20 ... 2nd desulfurization part, 100 ... Cylindrical tube, 200 ... Desulfurizing agent, 300 ... Dish, 400 ...・ ・ Reformer

Claims (3)

A first desulfurization section including a first desulfurization agent and a second desulfurization section provided downstream of the first desulfurization section in the gas flow direction and having a second desulfurization agent are provided.
The first desulfurizing agent contains activated carbon and a metal attached to the activated carbon.
The metal is a combination of copper and nickel.
The amount of copper attached is in the range of 2.0% by mass to 8.0% by mass with respect to the total mass of the first desulfurizing agent, and the amount of nickel attached is the amount of the first desulfurizing agent. It is in the range of 2.0% by mass to 8.0% by mass with respect to the total mass.
The second desulfurizing agent is a desulfurizer for fuel gas containing zeolite on which silver is supported. The desulfurizer for fuel gas according to claim 1, wherein the amount of nickel attached is in the range of 20% by mass to 80% by mass with respect to the total mass of the metal attached to the activated carbon. The desulfurizer for fuel gas according to claim 1 or 2, wherein the ratio of the amount of nickel attached to the amount of copper attached is in the range of 0.30 to 2.70 on a mass basis.

Images