JP2022000297A - Desulfurizer for fuel gas - Google Patents

Abstract

To provide a desulfurizer for fuel gas which can efficiently adsorb and remove a plurality of kinds of sulfur compounds contained in the fuel gas, which, as compared to the conventional desulfurizer using only silver-carrying zeolite as a desulfurizing agent, can reduce the amount of the silver-carrying zeolite used, and which can achieve the size reduction of the desulfurizer.SOLUTION: A desulfurizer for fuel gas includes: a first desulfurizing part including a first desulfurizing agent; and a second desulfurizing part which is arranged downstream of the first desulfurizing part in a gas flow direction and includes a second desulfurizing agent. The first desulfurizing agent contains active carbon and metals loaded on the active carbon. The metals are copper and nickel. The second desulfurizing agent contains zeolite on which silver is carried. A ratio between a volume X of the first desulfurizing agent and a volume Y of the second desulfurizing agent satisfies: X:Y=45:55 to 68:32.SELECTED DRAWING: Figure 1

Description

The present disclosure 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, and are therefore only used as industrial fuels, household fuels, etc. 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 is deteriorated.
For example, in the case of a fuel cell system, not only the catalyst in the reformer but also the electrode catalyst in the power generation cell is affected by the poisoning by the sulfur compound. Therefore, the sulfur compound contained in the fuel gas is not included. It is desirable to remove as much as possible in advance. Generally, in a fuel cell system, sulfur compounds contained in a fuel gas are removed by using a desulfurizer.

As the desulfurization method, for example, a room temperature adsorption desulfurization method and a hydrodesulfurization method 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 the sulfur compound contained in the gas is physically or chemically adsorbed on the surface of the desulfurization agent. .. The room temperature adsorption desulfurization method is widely used because it is easier to operate than the hydrodesulfurization method.

As the desulfurization technique of the room temperature adsorption desulfurization method, for example, a technique of using activated carbon on which a metal is supported (also referred to as "imposition") and a technique of using a zeolite on which a metal is supported are known.
For example, Patent Document 1 discloses a technique of using activated carbon impregnated with copper and nickel as metals (so-called metal-impregnated activated carbon) as a desulfurizing agent that efficiently adsorbs and removes sulfur compounds contained in fuel gas. ing.
Patent Document 2 describes a Y-type zeolite (so-called silver-supported zeolite) in which silver is supported by ion exchange as a desulfurizing agent that simultaneously adsorbs and removes sulfides and mercaptans in fuel gas such as city gas, LP gas, and natural gas. A technique for utilizing (zeolite) is disclosed.

Japanese Patent No. 6632279 Japanese Patent No. 4026700

By the way, various kinds of sulfur compounds are contained in the fuel gas. For example, mercaptans such as methyl mercaptan (MM: methyl mercaptan) and tert-butyl mercaptan (TBM: tertiary-butyl mercaptan) and dimethyl sulfide are added to the fuel gas for the purpose of detecting leakage. (DMS: dimethyl sulfide), sulfides such as dimethyl disulfide (DMDS: dimethyl disulfide), thiophenes such as tetrahydrothiophene (THT), and sulfur compounds such as cyclohexene (CH: cyclohexene) are contained.
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.
Further, during 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 there are a wide variety of sulfur compounds to be adsorbed, if all of these sulfur compounds are to be adsorbed and removed only with the metal-impregnated activated carbon described in Patent Document 1 or the silver-supported zeolite described in Patent Document 2, these A large amount of desulfurizing agent is required. In particular, since the raw material of silver-supported zeolite is expensive, the desulfurization cost increases as the amount used increases.

Considering that the spread of household fuel cell systems has become realistic in recent years, it is included in fuel gas more efficiently and at lower cost for desulfurizers for fuel gas. It is required that a plurality of types of sulfur compounds can be adsorbed and removed, and that the size can be reduced.

This disclosure has been made in view of the above circumstances.
The problem to be solved by one embodiment of the present disclosure is the conventional desulfurization that can efficiently adsorb and remove a plurality of types of sulfur compounds contained in the fuel gas and uses only silver-supported desulfurization as a desulfurization agent. 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 as compared with the vessel and can realize the miniaturization of the desulfurizer.

Specific means for solving the above problems include the following embodiments.
<1> A first desulfurization section provided with a first desulfurization agent and a second desulfurization section provided downstream of the first desulfurization section in the gas flow direction and provided with a second desulfurization agent are provided.
The first desulfurizing agent contains activated carbon and a metal impregnated with the activated carbon.
The above metals are copper and nickel.
The second desulfurizing agent comprises a silver-supported zeolite.
A fuel gas desulfurizer in which the ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is X: Y = 45: 55-68: 32.
<2> The first desulfurizing agent is the desulfurizer for fuel gas according to <1>, wherein the ratio of the amount of nickel attached to the amount of copper attached is 0.30 to 2.70 on a mass basis. ..
<3> The first desulfurizing agent has a copper content of 2.0% by mass to 8.0% by mass with respect to the total mass of the first desulfurizing agent <1> or <2>. Desulfurizer for fuel gas as described in.
<4> In the first desulfurizing agent, the amount of nickel attached is 2.0% by mass to 8.0% by mass with respect to the total mass of the first desulfurizing agent <1> to <3>. The desulfurizer for fuel gas according to any one of the above.

According to one embodiment of the present disclosure, 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 only silver-supported desulfurization as a desulfurizing agent. Therefore, a desulfurizer for fuel gas, which can reduce the amount of silver-supported zeolite used and can realize the miniaturization of the desulfurizer, is provided.

It is a schematic block diagram which shows the desulfurizer for fuel gas which concerns on this embodiment. In the evaluation test of the example, the adsorption amount of COS [unit: mass% S] and the ratio of the volume of the first desulfurizing agent to the total volume of the first desulfurizing agent and the second desulfurizing agent [unit:%]. It is a graph which shows the relationship of. The amount of various sulfur compounds (TBM, MM, and DMS) adsorbed in the evaluation test of the examples [unit: mass% S], and all the sulfur compounds adsorbed at the time of the first fracture. A graph showing the relationship between the total adsorption amount of sulfur compounds [unit: mass% S] and the ratio of the volume of the first desulfurizing agent to the total volume of the first desulfurizing agent and the second desulfurizing agent [unit:%]. Is.

Hereinafter, the desulfurizer for fuel gas disclosed in the present disclosure will be described in detail. The description of the requirements set forth below may be based on the exemplary embodiments of the present disclosure, but the present disclosure is not limited to such embodiments and is within the scope of the purposes of the present disclosure. Can be implemented with appropriate changes.

The numerical range indicated by using "~" in the present disclosure means a range including the numerical values before and after "~" as the lower limit value and the upper limit value, respectively.
In the numerical range described stepwise in the present disclosure, 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 the numerical range described in another stepwise description.
Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present disclosure, 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 desulfurization device for fuel gas of the present disclosure is arranged in 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 contained an activated charcoal and a metal adhering to the activated charcoal, the metals were copper and nickel, and the second desulfurizing agent was silver. The ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent containing zeolite (also referred to as “silver-supported zeolite”) is X: Y = 45: 55-68: 32. Is.
According to the desulfurizer for fuel gas of the present disclosure, a conventional desulfurizer capable of efficiently adsorbing and removing a plurality of types of sulfur compounds contained in the fuel gas and using only silver-supported zeolite as a desulfurizing agent is used. In comparison, the amount of silver-supported zeolite used can be reduced, and the desulfurizer can be downsized.
Although it is not clear why the desulfurizer for fuel gas of the present disclosure can exert such an effect, the present inventor speculates as follows.

The desulfurization device for fuel gas of the present disclosure is arranged in 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 through the first desulfurizing section provided with the first desulfurizing agent. Distribute the desulfurized part of.
The first desulfurizing agent is a desulfurizing agent in which activated carbon is impregnated with a specific metal, that is, copper and nickel, and has excellent desulfurization performance. Therefore, according to the first desulfurizing agent, the sulfur compound contained in the fuel gas can be adsorbed and removed with a relatively small amount of use. The first desulfurizing agent is particularly excellent in the adsorptive ability of mercaptans (particularly TBM), which are the main sulfur compounds contained in the city gas.
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 be excellent in the ability to adsorb sulfur compounds, but a large amount is required to adsorb all of a plurality of types of sulfur compounds only on silver-supported zeolite. Since the raw material of silver-supported zeolite is expensive, we want to reduce the amount used as much as possible.

In the desulfurization device for fuel gas of the present disclosure, by selecting a desulfurizing agent in which copper and nickel are impregnated with activated carbon as the first desulfurizing agent used in the first desulfurizing part through which the fuel gas first flows, the first method is used. The type and amount of the sulfur compound in the fuel gas flowing through the desulfurization portion of 1 is reduced by the first desulfurization agent. Therefore, in the second desulfurization section located downstream in the gas flow direction of the first desulfurization section, it is possible to reduce the amount of the second desulfurization agent required for adsorbing the sulfur compound, that is, the silver-supported zeolite. Will be. In addition, in the desulfurizer for fuel gas of the present disclosure, by setting the ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent within a specific range, a plurality of desulfurizing agents contained in the fuel gas are contained. Species of sulfur compounds can be efficiently adsorbed and removed.
That is, in the desulfurizer for fuel gas of the present disclosure, activated carbon impregnated with a specific metal such as copper and nickel (also referred to as "specified metal impregnated activated carbon") and silver-supported zeolite are selected as the desulfurizing agent. A multi-stage desulfurization method is used in which the fuel gas is distributed to a desulfurizer equipped with a specified metal-impregnated activated carbon as a desulfurizing agent and then distributed to a desulfurizer equipped with a silver-supported zeolite as a desulfurizing agent, and the specified metal-impregnated activated carbon is used. By setting the ratio of the volume of silver-supported zeolite to the volume of silver-supported zeolite within a specific range, the amount of silver-supported zeolite used can be reduced while efficiently adsorbing and removing multiple types of sulfur compounds contained in the fuel gas. be able to. Further, since the specified metal-impregnated activated carbon is excellent in the adsorption performance of sulfur compounds, it is possible to adsorb and remove a plurality of types of sulfur compounds contained in the fuel gas in a relatively small amount. Therefore, in the desulfurizer for fuel gas of the present disclosure, the amount of the desulfurizing agent used as a whole can be reduced, and as a result, the desulfurizer can be miniaturized.

Hereinafter, the desulfurizer for fuel gas disclosed in the present disclosure 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 desulfurizer for fuel gas according to the present embodiment. It should be noted that each element in FIG. 1 focuses on clearly showing the principle of the present disclosure, and is not necessarily an accurate scale.
The fuel gas desulfurizer 1 according to the present embodiment is arranged in a first desulfurization section 10 including a first desulfurization agent and downstream in 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 impregnated with the activated carbon, and the metals are copper and nickel. The second desulfurizing agent (not shown) included in the second desulfurization unit 20 contains silver-supported zeolite (silver-supported zeolite). The ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is set in a specific range of X: Y = 45: 55-68: 32.
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, the fuel gas containing the sulfur compound supplied to the desulfurizer 1 for fuel gas has flowed through the first desulfurization section 10 provided with the first desulfurization agent, and then the second desulfurization section provided with the second desulfurization agent. By circulating 20, a plurality of types of sulfur compounds contained in the fuel gas are adsorbed by the first desulfurizing agent and the second desulfurizing agent and removed.

The fuel gas containing the sulfur compound supplied to the desulfurization device 1 for fuel gas first flows through the first desulfurization unit 10 provided with the first desulfurization agent. The first desulfurizing agent is a desulfurizing agent capable of efficiently adsorbing a plurality of types of sulfur compounds contained in a fuel gas, and exhibits excellent adsorption ability with a relatively small amount of use. In the fuel gas flowing through the first desulfurization section 10 provided with the first desulfurizing agent, at least a part of the sulfur compound contained in the fuel gas is adsorbed and removed by the first desulfurizing agent, and then the second desulfurizing agent is used. A second desulfurization unit 20 comprising the above is distributed. The second desulfurizing agent does not require a large amount of use as long as it can adsorb a sulfur compound that cannot be completely adsorbed by the first desulfurizing agent. In addition, in the fuel gas desulfurizer 1, the ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is in a specific range of X: Y = 45: 55-68: 32. It has excellent removal efficiency of multiple types of sulfur compounds contained in fuel gas. As described above, according to the fuel gas desulfurizer 1 according to the present embodiment, a plurality of types of sulfur compounds contained in the fuel gas can be efficiently adsorbed and removed, and desulfurization using a conventional silver-supported zeolite is used. Compared with the vessel, the amount of silver-supported zeolite used can be reduced, and the desulfurization vessel can be downsized.

[First desulfurization section]
The first desulfurization unit includes a first desulfurization agent.
In the first desulfurization section, at least a part of the plurality of sulfur compounds contained in the fuel gas is adsorbed and removed by the first desulfurization agent.

<First desulfurizing agent>
The first desulfurizing agent contains activated carbon and a metal impregnated with the activated carbon, and the metals are copper and nickel.
According to the first desulfurizing agent, a plurality of types of sulfur compounds contained in the fuel gas can be efficiently adsorbed and removed.

(Activated carbon)
The first desulfurizing agent contains at least one type of activated carbon.
The activated carbon is not particularly limited, and for example, activated carbon usually used in the technical field of desulfurization agent can be used without particular limitation.

Examples of the raw material of activated carbon include palm husks, coal (anthracite, bituminous coal, etc.), wood flour, pete charcoal, and bamboo charcoal.
Among these, as a raw material for activated carbon, for example, coconut shell is preferable 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, and sulfuric acid.

The shape of the activated carbon is not particularly limited, and examples thereof include a granular shape, a columnar shape (eg, a columnar shape), a fibrous shape, a honeycomb shape, and a crushed shape.
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 shapes is preferable, and crushed shapes are more preferable.

When the shape of the activated carbon is granular, columnar, or crushed, and the gas flow rate is 10 L (liter) / min or less, the average particle size of the activated carbon is, for example, to prevent the outflow of gas and the outflow of desulfurizing agent. From the viewpoint, it is preferably 0.3 mm to 5.0 mm, more preferably 0.3 mm to 3.0 mm, and even more preferably 0.3 mm to 1.0 mm.
In the present disclosure, 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 1000 m ² / g or more, for example, from the viewpoint of improving the dispersity of the impregnated metal.
In the present disclosure, 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 to 2.0 nm, more preferably 0.9 nm to 1.5 nm, for example, from the viewpoint of having a pore diameter suitable for the molecular diameter of the sulfur compound. ..
In the present disclosure, 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 metals are copper and nickel.
Most of the metal impregnated in the activated carbon is considered to be contained as a compound containing a metal element (oxide, inorganic acid salt, organic acid salt, etc.), but may be contained as a single metal.

The amount of copper attached is, for example, preferably 1.0% by mass to 20.0% by mass, preferably 2.0% by mass to 15.0% by mass, based on the total mass of the first desulfurizing agent. More preferably, it is more preferably 2.0% by mass to 8.0% by mass.
The amount of nickel attached is, for example, preferably 1.0% by mass to 20.0% by mass, preferably 2.0% by mass to 15.0% by mass, based on the total mass of the first desulfurizing agent. More preferably, it is more preferably 2.0% by mass to 8.0% by mass.

The amount of copper attached is, for example, preferably 20% by mass to 80% by mass, more preferably 30% by mass to 80% by mass, and 40% by mass, based on the total mass of the metal attached to the activated carbon. It is more preferably% to 80% by mass, and particularly preferably 40% to 65% by mass.
The amount of nickel attached is, for example, preferably 20% by mass to 80% by mass, more preferably 20% by mass to 70% by mass, and 20% by mass, based on the total mass of the metal attached to the activated carbon. It is more preferably% to 60% by mass, and particularly preferably 35% by mass to 60% by mass.

The ratio of the amount of nickel attached to the amount of copper attached (nickel attachment amount / copper attachment amount) is preferably 0.30 to 2.70, preferably 0.30 to 2.50, on a mass basis. More preferably, it is more preferably 0.30 to 2.00, and particularly preferably 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.

In the present disclosure, the amount of metal impregnated in activated carbon (that is, the amount impregnated) 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 may contain activated carbon and components other than copper and nickel (so-called other components), if necessary, as long as the effects of the desulfurizer for fuel gas of the present disclosure are not impaired. good.
The first desulfurizing agent may contain a metal other than copper and nickel as an unavoidable component.

-Manufacturing method of the first desulfurizing agent-
The method for producing the first desulfurizing agent is not particularly limited.
The first desulfurizing agent can be produced by adopting a known method as a method of impregnating activated carbon with a metal.

An example of the method for producing the first desulfurizing agent will be described. The first desulfurizing agent can be produced, for example, according to the following procedures (1) to (4). However, the method for producing the first desulfurizing agent is not limited to this.

(1) A solution (so-called impregnated solution) is prepared in which a metal compound containing an element of a metal (that is, copper and nickel) to be impregnated with activated carbon is dissolved or dispersed in a solvent.
(2) Immerse activated carbon in the impregnated solution.
(3) The activated carbon immersed in the impregnated solution is dried to remove the solvent.
(4) The activated carbon that has been dried and soaked 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 procedure, the first desulfurizing agent can be produced.

The metal compound for preparing the impregnating solution is not particularly limited, and examples thereof include metal salt compounds such as metal nitrate, metal acetate, metal sulfate, metal chloride, and metal phosphate.
Specific examples of the metal compound for preparing the impregnating solution include copper nitrate trihydrate, copper acetate monohydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate, and 12-tangstophosphate n-water. Japanese products and ammonium molybdate tetrahydrate can be mentioned.

The solvent for preparing the impregnating solution is not particularly limited, and is, for example, water, an acidic aqueous solution (eg, nitrate aqueous solution), a basic aqueous solution (eg, ammonia aqueous solution), an alcohol solvent (eg, methanol, ethanol, and the like). n-propanol), ketone solvents (eg acetone, methyl ethyl ketone), ether solvents (eg diethyl ether), ester solvents (eg ethyl acetate and butyl acetate), hydrocarbon solvents (eg toluene), etc. Examples include solvents.
Among these, as the solvent for preparing the impregnating solution, for example, water is preferable from the viewpoint that it does not remain after firing.

In preparing the impregnating solution, only one kind of solvent may be used, or two or more kinds of solvents may be used.

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

The immersion temperature is not particularly limited and can be, for example, 10 ° C to 80 ° C.
The soaking time is not particularly limited and may be, for example, 5 minutes to 2 hours.

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

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

As the first desulfurizing agent, a commercially available product can be used.
As an example of a commercially available product of the first desulfurizing agent, HC-814NOB [trade name, shape: granular, raw material of activated carbon: coconut shell, treatment of activated carbon: nitrate treatment, particle size of activated carbon: 1.18 mm to 2.36 mm ( 97.6% by mass), less than 1.18 mm (2.4% by mass), specific surface area of activated carbon: 1200 m ² / g, average pore diameter of activated carbon: 1.1 nm, type of impregnated metal: copper and nickel, desulfurizing agent The amount of copper attached to the total mass of the activated carbon: 5.7% by mass, the amount of nickel attached to the total mass of the desulfurizing agent: 6.8% by mass, manufactured by Turmicol Co., Ltd.].
In the present disclosure, the commercially available product may be used as it is as the first desulfurization agent, but for example, the commercially available product may be crushed and then sized and used as the first desulfurization agent.

[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 is adsorbed by the second desulfurization agent and removed.
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 comprises a silver-supported zeolite (ie, a silver-supported zeolite).
The second desulfurizing agent adsorbs a sulfur compound that cannot be completely adsorbed by the first desulfurizing agent.

(Silver-supported zeolite)
Silver zeolite is a zeolite in 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 type of zeolite is not particularly limited.
Examples of the zeolite 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.
When the water concentration in the fuel gas is high, β-type zeolite is preferable as the zeolite.

The amount of silver carried is not particularly limited, but 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 can be, for example, 20% by mass or less.

(Other ingredients)
The second desulfurizing agent may contain components other than zeolite and silver (so-called other components), if necessary, as long as the effects of the desulfurizer for fuel gas of the present disclosure are not impaired.
Other components include a binder as a molding material.
Examples of the binder include alumina, silica, clay minerals and the like.
Further, the second desulfurizing agent may contain a metal other than silver as an unavoidable component as long as the effect of the desulfurizing device for fuel gas of the present disclosure is 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 granular, columnar (eg, columnar), honeycomb-like, and crushed shapes.
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 for example, the shape is high and the density is high. From the viewpoint of containing no 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.
The second desulfurizing agent can be produced by adopting a known method as a method for supporting silver on zeolite.
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, zeolite type: Y-type zeolite, silver carrier amount: 14% by mass with respect to the mass of zeolite, Nikki catalyst chemical formation Made by Co., Ltd.].

-Ratio of the volume X of the first desulfurizing agent and the volume Y of the second desulfurizing agent-
The ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is X: Y = 45: 55-68: 32, and X: Y = 48: 52 to 65:35. Is preferable, X: Y = 50:50 to 62:38 is more preferable, and X: Y = 53: 47 to 60:40 is even more preferable.
In the fuel gas desulfurizer of the present disclosure, when the ratio (X: Y) of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is within the above range, there are a plurality of types in the fuel gas. There is a tendency that the sulfur compound can be efficiently adsorbed and removed.

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

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

Fuel gas desulfurizer of the present disclosure, _{(S H} 2) hydrogen sulfide contained in the fuel gas, carbonyl sulfide (COS), cyclohexene (CH), mercaptans [Example: Methyl mercaptan (MM) and tert- butyl mercaptan (TBM)], sulfides [eg, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)], thiophenes [eg, tetrahydrothiophene (THT)], and various sulfur compounds can be efficiently adsorbed and removed. Moreover, 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, city gas and LP. 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 gas, natural gas, digestive gas, and exhaust gas.
Since the desulfurizer for fuel gas of the present disclosure can reduce the amount of silver-supported zeolite used, it is particularly suitable as a desulfurizer in a household fuel cell system, which is required to reduce the cost and size of the desulfurizer. It is preferably used.

[Manufacturing method of desulfurizer for fuel gas]
In the desulfurizer for fuel gas of the present disclosure, for example, the ratio of the first desulfurizing agent and the second desulfurizing agent to the volume X of the first desulfurizing agent and the volume Y of the second desulfurizing agent is X: Y. It can be produced by filling predetermined containers in order so that the ratio is 45:55 to 68:32.
Examples of the material of the container include materials such as 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 disclosure may be provided with a filter for preventing the second desulfurizing agent from scattering on the downstream side in the gas flow direction of the container.

Hereinafter, the desulfurizer for fuel gas of the present disclosure will be described in more detail with reference to Examples. The present disclosure is not limited to the following examples as long as the gist is not exceeded.
In this embodiment, in order to determine the breakthrough time at an early stage, the test is performed under the conditions where 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, tert-butyl mercaptan is referred to as "TBM", cyclohexene is referred to as "CH", dimethyl sulfide is referred to as "DMS", dimethyl disulfide is referred to as "DMDS", and tetrahydrothiophene is referred to as tetrahydrothiophene. It was described as "THT", carbonyl sulfide was described as "COS", methyl mercaptan was described as "MM", and hydrogen sulfide was described as "H ₂ S".

[Manufacturing of desulfurizer for evaluation test]
(Manufacturing Example A)
Commercially available metal-impregnated carbon [trade name: HC-814NOB, shape: crushed, raw material for activated carbon: coconut shell, treatment of activated carbon: nickel treatment, particle size of activated carbon: 1.18 mm to 2.36 mm (97.6% by mass)) , Less than 1.18 mm (2.4% by mass), Specific surface area of activated carbon: 1200 m ² / g, Average pore diameter of activated carbon: 1.1 nm, Type of impregnated metal: Copper and nickel, Copper to total mass of desulfurizing agent Amount of attachment: 5.7% by mass, amount of nickel attached to the total mass of desulfurizing agent: 6.8% by mass, ratio of the amount of nickel attached to the amount of copper attached in the desulfurizing agent (nickel attachment amount / copper attachment amount) ): 1.19 (based on mass), manufactured by Turmicol Co., Ltd.] was crushed using a Menou dairy pot, then sieved and sized, and the particle size was in the range of 0.35 mm to 0.71 mm. A desulfurizing agent was obtained. Next, the test tube (shape: cylindrical shape, inner diameter: 10.5 mm, length: 150 mm) is filled with the first desulfurizing agent so that the height of the packed bed is 34.7 mm, and the first A desulfurized part was prepared. The filling amount of the first desulfurizing agent is 3.0 cm ³ . A perforated plate was placed at the outlet of the test tube on the downstream side in the gas flow direction as a filter for preventing the scattering of the first desulfurizing agent.
As described above, the filling amount of the first desulfurization agent, and loading of the second desulfurizing agent were prepared respectively 3.0 cm ³ and 0.0 cm ³ at a production example A desulfurizer for evaluation test.

(Manufacturing Example B)
Commercially available silver-supported zeolite as a second desulfurizing agent in a test tube (shape: cylindrical, inner diameter: 10.5 mm, length: 150 mm) [trade name: FKS-A, shape: granular, type of zeolite: Y-type zeolite, supported amount of silver: 14% by mass based on the mass of zeolite, manufactured by Nikki Catalyst Kasei Co., Ltd.] was filled so that the height of the packed bed was 34.7 mm, and the second desulfurized portion. Was produced. The filling amount of the second desulfurizing agent is 3.0 cm ³ . A perforated plate was placed at the outlet of the test tube on the downstream side in the gas flow direction as a filter for preventing the second desulfurizing agent from scattering.
As described above, the filling amount of the first desulfurization agent, and loading of the second desulfurizing agent were prepared respectively 0.0 cm ³ and 3.0 cm ³ at a production example desulfurizer for evaluation test B.

[Evaluation of sulfur compound adsorption performance]
The sulfur compound adsorption performance was evaluated using fluid analysis simulation technology. Specifically, after constructing a desulfurizer model using general-purpose thermo-fluid analysis software (thermal-fluid analysis software: "Fluent" (registered trademark), version: 13.0, manufactured by ANSYS, USA), the first By simulating the results when the ratio of the volume of the first desulfurizing agent to the volume of the second desulfurizing agent is changed, the ratio of the volume of the first desulfurizing agent to the volume of the second desulfurizing agent can be determined. The effect on the sulfur compound adsorption performance of the desulfurizer was evaluated.
First, in order to construct a model of the desulfurizer, the following tests were performed on each of the evaluation test desulfurizer of Production Example A and the evaluation test desulfurizer of Production Example B produced above.
The desulfurization device for evaluation test was placed in a constant temperature bath, and the inside of the tank was kept warm at 25.0 ° 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 0.5 L / min. The dew point temperature of the test gas is −60.0 ° C. The test gas flows through the first desulfurization section and then through the second desulfurization section. The space velocity (SV) is 10000 L / hr, and the linear velocity (LV) is 9.62 cm / sec.

The test gas was flowed until a break point (breakage standard: 20 ppb) of all the sulfur compounds in the test gas was confirmed. Then, the amount of each sulfur compound adsorbed on the desulfurizing agent is calculated from the time from the flow of the test gas 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 breaking point of the sulfur compound is confirmed by collecting the gas discharged from the outlet of the desulfurizer for evaluation test every 3 hours and detecting the peak belonging to each sulfur compound by gas chromatography. did. The measurement conditions for gas chromatography are as follows.

(For sulfur compounds other than COS)
-Measurement conditions-
Gas chromatography system: GC-2014A [Model number, manufactured by Shimadzu Corporation]
Detector: Hydrogen flame ionization detector Analytical column: Shimalite 80/100 AW-AMDS-ST [Product name, size: 4.1 m x 3.2 mm I. D. , Made by Shinwa Kako Co., Ltd.]
Column temperature: 170 ° C
Injection amount: 3 mL
Data processing device: HP Z220 SFF Workstation

(In the case of COS)
-Measurement conditions-
Gas chromatography system: Agilent 7890B GC [trade name, manufactured by Agilent Technologies, Inc.]
Detector: Agent 8355 Chemiluminescent Sulfur Detector (SCD) [Product name, manufactured by Agilent Technologies, Inc.]
Analytical column: Agilent J & W DB-sulfur SCD [Product name, size: 60 m x 0.320 mm I. D. 4.20 μm, manufactured by Agilent Technologies, Inc.]
Column temperature: After holding at 60 ° C. for 7 minutes, the temperature is raised to 240 ° C. at a heating rate of 15 ° C./min, and then held at 240 ° C. for 5 minutes.
Injection amount: 2 mL
Split ratio: 5: 1
Data processing device: HP Z220 SFF Workstation

A model of the desulfurizer was constructed based on the amount of each sulfur compound adsorbed on the desulfurizing agent in the evaluation test desulfurizer of Production Example A and the evaluation test desulfurizer of Production Example B calculated above. Then, using the constructed desulfurizer model, the amount of each sulfur compound adsorbed on the desulfurizing agent when the ratio of the volume of the first desulfurizing agent to the volume of the second desulfurizing agent is changed is calculated by simulation. did.

Table 2 below shows the measurement results and simulation results of the adsorption amount of sulfur compounds. In Table 2, as representatives, the amount of COS, TBM, MM, and DMS adsorbed (unit: mass% S), and all the sulfur compounds adsorbed at the time of the first breakthrough. The measurement result and the simulation result of the total adsorption amount (unit: mass% S) of the sulfur compound are shown.
Further, the relationship between the amount of COS adsorbed (unit: mass% S) and the ratio of the volume of the first desulfurizing agent to the total volume of the first desulfurizing agent and the second desulfurizing agent (unit:%) is shown in FIG. The relationship between the amount of TBM adsorbed (unit: mass% S) and the ratio of the volume of the first desulfurizing agent to the total volume of the first desulfurizing agent and the second desulfurizing agent (unit:%), MM. Relationship between the adsorbed amount (unit: mass% S) and the ratio of the volume of the first desulfurizing agent to the total volume of the first desulfurizing agent and the second desulfurizing agent (unit:%), the adsorbed amount of DMS (unit:%) The relationship between the unit: mass% S) and the ratio of the volume of the first desulfurizing agent to the total volume of the first desulfurizing agent and the second desulfurizing agent (unit:%), and the sulfur compound that initially broke. The total adsorbed amount (unit: mass% S) of all the sulfur compounds adsorbed at the time of the breakthrough and the volume of the first desulfurizing agent with respect to the total volume of the first desulfurizing agent and the second desulfurizing agent. The relationship with the ratio (unit:%) is shown in FIG.

In Table 2, "-" in the column of the production example of the desulfurizer means that the desulfurizer is constructed by simulation.
In FIG. 3, the “total S adsorption amount” means “the total adsorption amount of all the sulfur compounds adsorbed at the time when the sulfur compound that first broke is broken”.

In Table 2, the value of "adsorption amount" is the amount of the sulfur compound adsorbed on the first desulfurizing agent and the second desulfurizing agent up to the breaking point, and the first desulfurizing agent and the first desulfurizing agent before adsorbing the sulfur compound. The value obtained by dividing by the total mass of the second desulfurizing agent and converting the obtained value into a sulfur element (unit: mass% S) is shown.
Specifically, the "adsorption amount" is calculated by the following formula.
In the formula below, "ntp" is an abbreviation for "normal temperature pressure".

Adsorption amount [Unit: Mass% S] = Concentration of sulfur compound in test gas [mgS / m ³ ] x Flow rate of test gas [Unit: m ³ (ntp)] ÷ 1st desulfurization agent and 2nd Total mass of desulfurizing agent [Unit: mg] x 100

As shown in Table 2, FIG. 2, and FIG. 3, a first desulfurization section including a first desulfurization agent and a second desulfurization section arranged downstream in the gas flow direction of the first desulfurization section are provided. A second desulfurization section is provided, the first desulfurizing agent contains activated charcoal and a metal impregnated with the activated charcoal, the metals are copper and nickel, and the second desulfurizing agent is silver. According to the desulfurizer, the ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is X: Y = 45: 55-68: 32. For example, it was possible to efficiently adsorb and remove a plurality of types of sulfur compounds from the sulfur compounds in the test gas. From this result, according to the present disclosure, 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. It is thought that it can be realized.

1 ... Fuel gas desulfurizer, 10 ... 1st desulfurization section, 20 ... 2nd desulfurization section

Claims (4)

A first desulfurization section provided with a first desulfurization agent and a second desulfurization section provided downstream of the first desulfurization section in the gas flow direction and containing a second desulfurization agent are provided.
The first desulfurizing agent contains activated carbon and a metal impregnated with the activated carbon.
The metals are copper and nickel.
The second desulfurizing agent comprises a silver-supported zeolite.
A fuel gas desulfurizer in which the ratio of the volume X of the first desulfurizing agent to the volume Y of the second desulfurizing agent is X: Y = 45: 55-68: 32. The desulfurizer for fuel gas according to claim 1, wherein the first desulfurizing agent has a ratio of the amount of nickel attached to the amount of copper attached 0.30 to 2.70 on a mass basis. The first desulfurizing agent according to claim 1 or 2, wherein the amount of copper attached to the first desulfurizing agent is 2.0% by mass to 8.0% by mass with respect to the total mass of the first desulfurizing agent. Desulfurizer for fuel gas. The first desulfurizing agent is any one of claims 1 to 3, wherein the amount of nickel attached is 2.0% by mass to 8.0% by mass with respect to the total mass of the first desulfurizing agent. The desulfurizer for fuel gas according to item 1.

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