WO2004080588A1

WO2004080588A1 - Desulfurizing agent and method for production thereof, method for desulfurization, and method for producing hydrogen for fuel cell

Info

Publication number: WO2004080588A1
Application number: PCT/JP2004/003032
Authority: WO
Inventors: Michihiro Ishimori; Masafumi Katsuta; Tetsuji Suzuki; Koichiro Furusawa
Original assignee: Waseda University
Priority date: 2003-03-11
Filing date: 2004-03-09
Publication date: 2004-09-23
Also published as: JP2004290955A; JP4625970B2; TW200500135A

Abstract

A desulfurizing agent, characterized in that it is represented by the general formula: ZnFe2O4/SiO2/a molybdenum compound (MoS2 and/or MoO3), or ZnFe2O4/SiO2/a molybdenum compound (MoS2 and/or MoO3)/a titanium compound(TiO2); a method for producing the desulfurizing agent; a desulfurizing method which comprises contacting a sulfur-containing compound with the desulfurizing agent; and a method for producing a highly pure and highly desulfurized hydrogen gas which comprises the desulfurization using the desulfurizing agent followed by a reforming treatment. The desulfurizing agent exhibits high performance capability and allows sulfur to be removed from a sulfur-containing compound instantaneously in an one stage process with high efficiency, and also can be regenerated and used repeatedly. Further, the desulfurization using the desulfurizing agent can be temporarily stopped. The above method for producing hydrogen can be employed for producing a hydrogen gas for use in a fuel cell on a large scale at a low cost.

Description

Description Desulfurizing agent and method for producing the same,

Desulfurization method and method for producing hydrogen for fuel cell

The present invention relates to a desulfurizing agent, a method for producing the same, a method for producing desulfurization, and a method for producing hydrogen for a fuel cell, and in particular, can efficiently remove sulfur from various sulfur-containing compounds such as organic sulfur-containing compounds. A method for producing a desulfurizing agent and an economical and efficient desulfurizing agent, a desulfurizing method using the desulfurizing agent, and a method for producing high-purity hydrogen and advanced desulfurized hydrogen for a fuel cell using the desulfurizing agent About. Background art

In recent years, fuel cells have been spotlighted at home and abroad as a highly efficient energy conversion technology with excellent environmental properties.

Depending on the type of electrolyte used, this fuel cell is available in a phosphoric acid type, a molten carbonate type, a solid oxide type, a solid polymer type, etc. Particularly, solid polymer fuel cells operate at low temperatures. As a result, it is drawing attention as a power source for next-generation fuel cell vehicles.

Fuel cells can efficiently convert chemical energy into electric energy by electrochemically reacting hydrogen and oxygen. However, hydrogen as a raw material source must have high purity.

Such hydrogen sources include methanol, liquefied natural gas, city gas, and synthetic liquid fuels.

(GT L), Biofuel, Waste plastic oil, Petroleum naphtha, Gasoline, Light Petroleum hydrocarbon compounds such as oil can be obtained.Especially as petroleum hydrocarbon compounds are easy to store and handle, and the supply facilities at gas stations and other facilities are provided, which is an advantageous source of hydrogen. is there.

However, petroleum-based hydrocarbon compounds have the disadvantage of having a high sulfur content.- 'In this case, sulfur corrodes the fuel cell electrodes. Must be removed to tens of ppb levels, but it has not yet been established to effectively cleave the CS bond in addition to the HS bond in sulfur compounds to achieve high desulfurization efficiency.

Further, fuel oil is generally subjected to reforming treatment such as steam reforming, partial reforming, and autothermal reforming, but the reforming catalyst is poisoned by sulfur content. Therefore, it is necessary to highly desulfurize the sulfur content in fuel oil.

Currently used desulfurization methods for hydrogen sulfide (H ₂ S) include a wet method and a dry method. The wet method has a problem that the desulfurization temperature is low and the energy loss is large, while the dry method has a small energy loss and a high desulfurization temperature, and is currently commercially available (particularly, No resulfurization method has been developed yet.

Commonly used dry desulfurization agents include iron oxide and zinc oxide. Iron oxide as a conventional dry desulfurization agent does not have a very high ability to remove sulfur compounds, and therefore iron oxide should be used in fuel cells that have a significant decrease in performance due to the presence of sulfur compounds, such as fuel cells. It does not have sufficient performance as a desulfurizing agent.

In addition, zinc oxide used as a desulfurizing agent has a poor absorption capacity for sulfur compounds, is difficult to regenerate, and cannot be used repeatedly.

On the other hand, hydrogen production methods using advanced natural gas desulfurization include natural gas reforming. There is a way. Hydrogen reformed from natural gas and highly desulfurized can be used for fuel cells and the like. Conventional methods for producing such highly desulfurized hydrogen include flowing natural gas into a desulfurization apparatus, precision desulfurizing hydrogen sulfide with zinc oxide or the like to obtain highly desulfurized natural gas, and then modifying the resulting highly desulfurized natural gas. High-desulfurized hydrogen is obtained by feeding the gas into the gasifier.

However, zinc oxide and the like used in such conventional methods for desulfurizing natural gas are discarded and cannot be reused. If the concentration of hydrogen sulfide in natural gas is high (30 to 1000 ppm), perform crude desulfurization using MDEA (amine) before performing precision desulfurization. Required, and the process becomes complicated. In order to solve such problems, Japanese Patent Application Laid-Open No. Hei 4-74526 discloses a method for producing zinc ferrite used as a desulfurizing agent. Zinc ferrite, which is used as a desulfurizing agent, is intended to improve the efficiency of removing sulfur compounds and increase its absorption capacity by being made into a zinc-iron ferric binary oxide.

However, when used in the desulfurization step, the zinc fluoride desulfurizing agent decomposes the desulfurizing agent or deposits carbon inside the desulfurizing agent to block pores of the desulfurizing agent for diffusing the sulfur compound gas, Desulfurization efficiency is reduced by producing by-products not involved in desulfurization. Also, the desulfurization performance of the desulfurizing agent after regeneration will be significantly reduced.

Further, Z n F e ₂ 〇 ₄ _ S i O ₂ was added to the silica to zinc ferrite as desulfurizing agent has been proposed. Such desulfurization agent, although more desulfurization performance is improved on the addition of Z n F e ₂ 〇 ₄ fc S I_〇 _2, desulfurization performance after regeneration will be significantly reduced, it is filed difficult to repeatedly use Was.

Further, JP-A-2003-643866 discloses a desulfurizing agent having a catalytically active metal supported on a zeolite carrier as a desulfurizing agent for removing sulfur compounds in a fuel gas. However, such desulfurizing agents desulfurize sulfur compounds by adsorption from fuel gas, and it is difficult to apply such desulfurizing agents to liquid fuels. The desulfurization performance of the steel significantly deteriorated, and it was difficult to use it repeatedly.

Accordingly, an object of the present invention is to provide an ultra-high-performance desulfurizing agent capable of instantaneously removing sulfur from a sulfur-containing compound with high efficiency in a one-step process (conventionally a three-step process) and capable of repeated regeneration. It is to be.

Another object of the present invention is to provide a method for producing a desulfurizing agent capable of economically and efficiently producing such a desulfurizing agent.

Still another object of the present invention is to provide a desulfurization method capable of efficiently and efficiently removing a sulfur component in a sulfur-containing compound using the desulfurizing agent of the present invention.

Still another object of the present invention is to use a desulfurizing agent of the present invention to highly efficiently remove a sulfur component in a sulfur-containing compound and to perform a reforming treatment to obtain a high-purity hydrogen for a fuel cell. It is an object of the present invention to provide a method for producing a large amount of highly desulfurized hydrogen at low cost. Disclosure of the invention

The present inventors have conducted research to solve the above-mentioned problems, and as a result, a desulfurizing agent having a specific composition can efficiently cut various sulfur bonds such as a hydrogen-sulfur bond and a carbon-sulfur bond to improve desulfurization performance. At the same time, they have found that a desulfurizing agent whose desulfurization performance does not deteriorate even after repeated use after regeneration can be obtained, and have reached the present invention.

The desulfurizing agent of the present invention has the following general formula:

Z n Fe ₂ 0 ₄ ZS i〇Nomolybdenum compound

(Wherein, the molybdenum compound represents Mo S ₂ and Z or Mo O 3). The desulfurizing agent of the present invention has the following general formula:

_{_{Z n F e 2 0 4 /}} S i O 2 molybdenum compound / titanium compound

(Wherein, the molybdenum compound, the M o S ₂ and / or M o O _3, also titanium compounds show T 1_Rei ₂₎ characterized in that it comprises a compound represented by.

The method for producing a desulfurizing agent of the present invention have the formula: zinc ferrite silica represented by _{_{Z n F e 2 0 4 ZS}} i 0 2, molybdenum compounds (molybdenum compound, M o S ₂ and / Or Mo 3), or a molybdenum compound and a titanium compound (a titanium compound shows Ti ₂ ), pulverize and mix, and add a molding aid to the resulting mixture. It is characterized by firing.

The desulfurization method of the present invention is characterized in that when desulfurizing from a sulfur-containing compound, the desulfurizing agent of the present invention is desulfurized by contact with the sulfur-containing compound. Preferably, in the above desulfurization method, it is desirable that the used desulfurizing agent is regenerated by acidification and the regenerated desulfurizing agent is used repeatedly.

Alternatively, in the above desulfurization method, it is desirable to temporarily stop the contact between the desulfurizing agent and the sulfur-containing compound, and then contact the desulfurizing agent and the sulfur-containing compound again.

Further, the method for producing hydrogen for a fuel cell according to the present invention is characterized in that the sulfur-containing compound is brought into contact with the desulfurizing agent of the present invention to desulfurize the sulfur-containing compound, and then subjected to steam reforming.

The desulfurizing agent of the present invention is a high-performance desulfurizing agent capable of repetitive desulfurization regeneration. By using such a desulfurizing agent, it is possible to highly efficiently remove a sulfur content in a sulfur-containing compound and perform a reforming treatment. As a result, high-purity hydrogen and highly desulfurized hydrogen can be easily produced economically. Therefore, in fields where the allowable sulfide concentration in hydrogen gas is extremely severe, such as fuel cells such as scale acid fuel cells and polymer electrolyte fuel cells, in which the electrodes and catalysts are susceptible to degradation due to the reaction with hydrogen sulfate, etc. Can also be used very effectively. Further, the method for producing a desulfurizing agent of the present invention enables the desulfurizing agent of the present invention to be produced economically and efficiently.

INDUSTRIAL APPLICABILITY The desulfurization method of the present invention is capable of highly efficiently removing the sulfur content in a sulfur-containing compound and has a level of 100 ppb or less. For example, a natural gas such as city gas or LP gas has a level of 30 ppb or less. Until the sulfur concentration can be reduced. In addition, by using the desulfurizing agent of the present invention, the desulfurization start time is shortened, but excellent desulfurization performance is achieved, such as intermittent use in which desulfurization reaction is temporarily stopped and re-desulfurization reaction is repeated during desulfurization. have. That is, desulfurization can be easily started and stopped.

Furthermore, the desulfurizing agent of the present invention is used to highly efficiently remove the sulfur content of the sulfur-containing compound and perform a reforming treatment, thereby reducing a large amount of high-purity hydrogen for fuel cells and highly desulfurized hydrogen. It enables production at a low cost. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a desulfurizing agent of the present invention _{_{(ZnFe 2 0 4 / S i}} 0 2 / Mo0 3) diagram showing the relationship of the desulfurization characteristics of time and the concentration of hydrogen sulfide (ppm) of (desulfurizing agent: Oxidation regeneration method; hydrogen sulfide concentration: gas at the desulfurization unit outlet).

Figure 2 is a desulfurizing agent of the present invention (ZnFe ₂ 〇 _{_{4 / S i 0 2 / MoS}} 2) diagram showing the relationship of the desulfurization characteristics of time and the concentration of hydrogen sulfide (ppm) of (desulfurizing agent: Oxidation regeneration method; hydrogen sulfide concentration: gas at the desulfurization unit outlet).

Fig. 3 is an enlarged view (hydrogen sulfide concentration; ppb) of part of Fig. 2. Figure 4 is a desulfurization cycle times and hydrogen sulfide absorption the relationship between the (experimental value Z theory) is a diagram showing the desulfurization agent of the present invention _{_{(ZnFe 2 0 4 / S i}} 0 2 Mo0 3). Figure 5 shows the relationship between the number of desulfurization cycles and the amount of hydrogen sulfide absorbed (experimental / theoretical values). Is a diagram showing the desulfurization agent of the present invention _{_{(ZnF e 2 0 4 / S}} i 0 2 / Mo S 2). Figure 6 is a desulfurization characteristics of the desulfurization agent of the present invention _{_{(ZnFe 2 0 4 XS i 0}} 2 / MoS 2), the relationship between time and concentration of hydrogen sulfide (ppb) and dimethyl sulphates id Concentration (ppm) (Desulfurizing agent: oxidation regeneration method; sulfide hydrogen concentration and dimethyl sulfide concentration: gas at the desulfurizer outlet).

Figure 7 is a desulfurization characteristics of the desulfurization agent of the present invention _{_{(ZnFe 2 0 4 "S i}} 0 2 / MoS 2), the relationship between the time and the methane concentration (ppm) and dimethyl sulphates id Concentration (ppm) (Desulfurizing agent: oxidation regeneration method; methane concentration and dimethylsulfide concentration: gas at the exit of the desulfurization unit).

Figure 8 is a desulfurizing agent of the present invention (ZnFe ₂ 0 ₄ ZS I_〇 _{_₂} ZMoS ₂ ZTi0 ₂₎ diagram showing the relationship of the desulfurization characteristics of time and the concentration of hydrogen sulfide (ppb) of (desulfurizing agent: oxidizing Regeneration method; hydrogen sulfide concentration: gas at the desulfurization unit outlet).

Figure 9 is a desulfurizing agent (ZnFe ₂ 0 ₄ ZS I_〇 ₂ ZMOS ₂ Bruno T I_〇 ₂₎ time desulfurization characteristics and methane concentration (ppm) and of dimethyl sulphates id concentration of the present invention (pp m) (Desulfurizing agent: oxidation regeneration method; methane concentration and dimethyl sulfide concentration: gas at the desulfurization unit outlet).

Figure 10 is a desulfurizing agent (ZnFe ₂ 〇 _{_{4 ZS i 0 2 / M o}} S 2 / T i 0 2) Time and hydrogen sulfide concentration desulfurization characteristics of (PP b) and dimethyl sulfide concentration of the present invention (p pm) (desulfurization agent: oxidation regeneration system; hydrogen sulfide concentration and dimethyl sulfide concentration: gas at the desulfurization unit outlet).

FIG. 11 is a desulfurization agent _{_{(ZnFe 2 0 4 / S i}} 0 2 / Mo S 2 / T i 0 2) the desulfurization characteristic time and methane concentration (ppm) and dimethyl sulfide concentration of the present invention (ppb) This is a diagram showing the relationship (desulfurizing agent: desulfurization reaction suspension method; methane concentration and dimethylsulfide concentration: gas at the desulfurization unit outlet). FIG. 12 is a desulfurization agent of the present invention _{_{(ZnFe 2 0 4 / S i}} 0 2 / UoS 2 / T i 0 2) the desulfurization characteristic time and the concentration of hydrogen sulfide (ppb) and dimethyl sulphates id Concentration (pp b ) (Desulfurizing agent: method for temporarily stopping the desulfurization reaction; hydrogen sulfide concentration and dimethyl sulfide concentration: gas at the exit of the desulfurization unit). BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described based on the following preferred examples.

A preferred desulfurizing agent of the present invention has the following general formula:

_{_{ZnFe 2 0 4 / S i 0}} 2 / molybdenum compound

(Wherein molybdenum compounds show Mo S ₂ and Z or Mo 0 _3), or, ZnFe ₂ 〇 ₄ / S i 0 ₂ Z molybdenum compound / titanium compound

(Wherein, the molybdenum compound, the MoS ₂ and Z or MO0 _3, also titanium compounds show T I_〇 ₂₎ a compound represented by.

Mo S ₂ and / or MO0 ₃ is a molybdenum compound in the above formulas, the carbon of the sulfur-containing compounds - has a function of sulfur bonds as a catalyst for cutting out the _{_{hydrogenation, Z nFe 2 0 4 / S}} i 0 has a function as the _second structural stability I匕剤, especially to allow the maintenance of high performance of a desulfurizing agent after regeneration.

Mo S ₂ and Z or Mo_〇 as these structures stabilizers _3, T I_〇 ₂ to stabilize the bond with similarly sigma 11 6 ₂ 0 ₄ and 3 i 0 ₂ and, the reproduction process after the desulfurization Has a function of preventing agglomeration of zinc ferrite.

If necessary, by using a combination of the T i 0 ₂ as Mo S ₂ and / or Mo 0 ₃ and a carrier, repeated pause and re-reaction of the significant reduction and desulfurization reaction of the desulfurization start time Intermittent use is also possible. That is, high-efficiency desulfurization can be started instantaneously, desulfurization can be stopped, and desulfurization can be restarted easily. The method for producing the desulfurizing agent of the present invention will be described below.

The production method is as follows: a precursor of iron oxide and zinc oxide is mixed with a precursor of silicon oxide, and iron, zinc and silicon components are contained in the form of τ-oxide by coprecipitation or homogeneous precipitation. the precipitate was allowed to form, filtered, dried and washed, by firing, further by grinding if necessary, ZnFe ₂ 0 ₄ - producing S I_〇 _2.

The form of addition of silicon is not particularly limited as long as zinc, iron and silicon can interact with each other.

The mixing ratio of zinc and iron (Zn: Fe) is not particularly limited, but the molar ratio is 1: 2 to 1: 4, preferably 1: 2 to 1: 3, in terms of desulfurization efficiency with respect to the amount of desulfurizing agent used. Is preferred.

Also, the amount of silicon oxide added is not particularly limited, but the weight ratio (S i 0 ₂ / ZnFe ₂ 0 ₄ ) of 211 6 ₂ 〇 ₄ to 3 i 0 ₂ may be 1 Z4 to 2Z 1. It is preferable from the viewpoint of the desulfurization performance of the obtained desulfurizing agent.

As a precursor of iron oxide or zinc oxide, for example, a water-soluble salt such as nitrate, sulfate and chloride can be used. In addition, as silicon, as a precursor of silicon oxide, silicate, colloidal silicide, amorphous silicide, or the like can be used.

Specifically, after stirring an aqueous solution in which these iron precursor, zinc precursor, and silicon precursor are mixed, a hydroxide is formed by a coprecipitation method using ammonia or the like or a uniform precipitation method using urea or the like. As a precipitate. Sodium hydroxide and potassium hydroxide can also be used as other additives for obtaining the precipitate. This precipitate is aged, washed, filtered, dried, and fired at a temperature of, for example, 300 to 900 ° C. If necessary, by Kona碎the obtained baked _{_{product, Z n F e 2 0 4}} - producing S i O _2. Then, the resulting ZnFe ₂ 0 ₄ - a Mo S ₂ and Z or MO0 ₃ as a structural stabilizer to the S i 0 ₂ calcined product, further adding T i 0 _2. The mixtures were mixed Kona碎and calcined by adding a molding aid to the mixture obtained, the present invention _{_{ZnF e 2 0 4 - S i}} 0 2 - molybdenum compound, or, ZnFe ₂ 0 ₄ -S i 0 ₂ _ molybdenum compound one titanium compound (wherein, the molybdenum compound, a Mo S ₂ and / or Mo_〇 _3, also titanium compounds show T I_〇 ₂₎ obtained.

The amount of Mo S ₂ , Mo 0 ₃ , and even T i 0 ₂ to be added is not particularly limited, but preferably the total addition amount is 1 to 3 times the weight of ZnFe ₂ 0 ₄ —S i 0 ₂ The degree is preferred from the viewpoint that the desulfurizing performance of the obtained desulfurizing agent is maintained even after regeneration.

If the addition of T i 0 _2, its weight 1-5 times the molybdenum compound are preferred from the viewpoint of reactivity of the desulfurizing agent.

When molding the desulfurizing agent, organic substances such as methylcellosolve, polyethylene glycol, polyvinyl alcohol, starch, and lignin can be used as a molding aid.

Further, it is also possible to add an inorganic agent such as glass fiber, carbon fiber, metal fiber and the like to mold.

Next, firing is performed at a temperature of 400 to 700 ° C., and firing and forming into any desired shape such as, for example, granular, pellet, spherical, cylindrical, 82-cam, plate, etc. ₂ 〇 ₄ one S I_〇 ₂ - molybdenum compound, or, ZnFe ₂ 0 ₄ -S I_〇 _2-molybdenum compound one titanium compound (molybdenum compound, 03 ₂ and or MO0 _3, also titanium compound T i 0 ₂ Is obtained).

By bringing the desulfurizing agent of the present invention thus obtained into contact with an organic sulfur-containing compound such as natural gas, city gas, or LP gas, or a sulfur-containing compound such as H ₂ S, these sulfur-containing compounds are obtained. From the sulfur content. Specifically, for example, natural gas, city gas, LP gas, or the like is heated and vaporized, and the desulfurizing agent of the present invention is vapor-desulfurized with hydrogen together with hydrogen to thereby desulfurize sulfur. As the hydrogen used here, it is natural that hydrogen obtained by a hydrogen production process described later may be circulated and used.

The desulfurization conditions are not particularly limited, and various settings can be made depending on the properties of the organic sulfur-containing compound.However, it is preferable that the temperature is 300 to 60 ° C and the pressure is in the range of normal pressure to IMPaG. It is desirable because of the reactivity of the desulfurizing agent and the economics of the desulfurization equipment.

Gasoline, a typical example of liquid fuels containing organic sulfur-containing compounds, contains many sulfur sulfides, such as thiophenes, mercaptans, and sulfides, and the binding energy of C-S bonds in them The properties are similar to dimethyl sulfide (R ₂ S), and the reaction to hydrocrack the sulfur compounds in gasoline into hydrogen sulfide and hydrocarbons should be considered in terms of the molecular size of the sulfur compounds. However, it is basically the same as the desulfurization reaction of dimethyl sulfide.

The desulfurization method of the present invention is effective for desulfurization of an organic sulfur-containing compound.

Such a mechanism is represented by, for example, the following mechanism (where R represents a hydrocarbon group).

Desulfurization (C-S bond breaking, H ₂ S generation)

(Catalyst: molybdenum compound);

RSH + H ₂ → RH + H ₂ S

R ₂ S + H ₂ → RH + H ₂ S

Desulfurization (H ₂ S absorption);

_{_{_{H 2 S + ZnFe 2 0 4}}} + H 2 -> ZnS + Fe S + H 2 0

As described above, the desulfurizing agent of the present invention comprises a desulfurizer (C-S bond) Since the cleavage and H ₂ S generation) reactions and the desulfurization (H ₂ S absorption) reaction can proceed simultaneously, the desulfurization method of the present invention removes the organic sulfur compounds in the organic sulfur-containing compounds in a step. This is an ultra-high-performance desulfurization method that enables the sulfur concentration of organic sulfur-containing compounds with a sulfur concentration of 1000 pm or more to be reduced to 100 ppb or less.

In the conventional desulfurization technology, the organic sulfur compound in the organic sulfur-containing compound is usually removed in the following three reaction steps.

(1) Hydrocracking reaction process (C_S bond cleavage, H ₂ S formation reaction): Use of hydrogenation catalyst

(2) H ₂ S removal reaction process (crude desulfurization, H ₂ S absorption reaction): Use MDEA (amine)

(3) H ₂ S removal reaction process (precision desulfurization, H ₂ S absorption reaction): use of zinc oxide, etc. The desulfurization method of the present invention uses a super-high This is a high-performance desulfurization method, and is a highly efficient method compared to conventional desulfurization methods. In addition, since the desulfurization method of the present invention is a high-performance desulfurizer, catalyst poisoning in the downstream reforming process (for hydrogen production) is eliminated or greatly reduced. Furthermore, since it is a renewable desulfurizing agent, it can be evaluated as excellent in terms of environmental preservation, resource reuse, system compactness, and economic efficiency.

The sulfur-containing compound that can be used in the desulfurization method of the present invention is not particularly limited as long as it can perform gas-phase desulfurization. Natural gas, city gas, alcohol, ether, LPG, naphtha, gasoline, kerosene, gas oil And various organic sulfur-containing compounds such as coal liquefied oil, and sulfur compounds such as hydrogen sulfide. It is also applicable to high-grade desulfurization and high-purification of by-product hydrogen from petroleum refining, steel industry, and hydrogen-based gas obtained from hydrogen-producing bacteria from organic waste.

In addition, the desulfurizing agent of the present invention, after being used as a desulfurizing agent, It can be regenerated by oxidation, and the regenerated desulfurizing agent can be used repeatedly. Even by such repeated use, the desulfurization performance is not deteriorated but rather improved. Also, in the desulfurization reaction, intermittent use in which pause and re-desulfurization reaction are repeated is possible, and excellent desulfurization performance can be exhibited.

This is because, as described above, the structure of the desulfurization agent of the present invention, Mo S ₂ and Mo O _3, and T i 0 ₂ is Z nFe ₂ 0 ₄ and S i 0 be used as the titanium compound for use as a molybdenum compound _This is because it has a function of stabilizing the bond with ₂ and preventing aggregation of zinc ferrite in the regeneration treatment after desulfurization.

Also, initially, when the _{_{_{ZnFe 2 0 4 ZS i 0 2}}} ZMo 0 3 desulfurization agent, desulfurization reaction - but (C S bond hydrogenation cleavage reaction) was prevented somewhat by the molybdenum compounds will sulphide, It is thought that the desulfurization reaction is activated.

On the other hand, in the case of _{_{ZnFe 2 0 4 / S i 0}} 2 / Mo S 2 based desulfurizing agent, as in the case of the / MO0 ₃ desulfurization agent, and more to exhibit excellent desulfurization performance each time repeating the desulfurization , ZnF e ₂ 〇 _{_{4 ZS i 0 2 / Mo S}} 2 and Z n F e ₂ 〇 _{_{4 / S i 0 2 / M}} o0 3 desulfurization agent of the present invention, repeating the desulfurization, molybdenum oxide or molybdenum sulfide Thus, the molybdenum compound itself is considered to contribute to the desulfurization regeneration reaction without interfering with the desulfurization reaction.

It is considered that the titanium compound (Ti ₂ ) used as a carrier has a function of promptly performing the above reaction.

The desulfurization performance of the regenerated desulfurization agent obtained in this way shows better desulfurization performance than that of a newly prepared desulfurization agent. For example, dimethylsulfide is below the detection limit (30 ppb or less; equilibrium theoretical). 1 ppb or less) and hydrogen sulfide can be reduced to 3 O ppb or less.

Further, the method for producing high-purity hydrogen of the present invention, in particular, the method for producing hydrogen for a fuel cell, comprises: After the desulfurization step, high-purity hydrogen or highly desulfurized hydrogen can be produced by steam reforming and CO modification.

Such a mechanism is represented by the following mechanism.

Steam reforming _{_{C n H 2n + 2 + H}} 2 0 → H 2 + CO + C0 2

CO-modified _{_{CO + H 2 0 → H 2}} + C0 2

In the present invention, advanced desulfurization is carried out in a desulfurization unit, and then the gas discharged from the desulfurization unit is passed through a reforming unit, and a part of the H ₂ gas reformed and generated in the reforming unit is, for example, about 5% By returning the hydrogen gas to the upstream of the desulfurization unit, the desulfurized material flowing into the desulfurization unit is highly desulfurized as a hydrogen reducing atmosphere, and this highly desulfurized product is sent to the reforming unit to achieve the advanced desulfurization. Desulfurized hydrogen is obtained.

As described above, when the desulfurizing agent of the present invention is used, the decomposition of sulfur compounds such as organic sulfur-containing compounds and the absorption of hydrogen sulfide can be simultaneously advanced. For example, natural gas, city gas, LP gas, etc. Pure hydrogen or highly desulfurized hydrogen can be obtained easily and economically.

Therefore, high-purity hydrogen can be obtained even in fields where the allowable sulfide concentration in hydrogen gas is severe, such as phosphoric acid fuel cells and solid polymer fuel cells whose electrodes are easily degraded by reaction with hydrogen sulfide, etc. Therefore, it is very effective in industry. Further, it can be easily applied to a fuel cell such as a molten carbonate fuel cell or a solid electrolyte fuel cell. Example

The present invention will be described more specifically with reference to the following examples, comparative examples, and test examples, but the present invention is not limited to these examples.

Example 1

About 22.3 g of zinc nitrate hexahydrate, about 60.6 g of iron (III) nitrate nonahydrate, About 30.1 g of the toroidal silica and 150 ml of distilled water were added and mixed with stirring. About 35 ml of ammonia was added to the obtained mixed solution to adjust the pH of the solution to 7, and a hydroxide was coprecipitated.

The obtained hydroxide is aged for 1 hour, filtered, washed 5 times with pure water, dried with 12 O: for 12 hours, then heated in an electric furnace to 80 Ot in 3 hours, and then 800 ° C in calcined 5 hours, and pulverized in a mortar, ZnFe ₂ 0 ₄ - was obtained S i 0 _2.

Then, ZnF e ₂ 0 ₄ obtained - against S i 0 _2, twice the Mo 0 ₃ was added pressure by weight, the lignin as a molding aid were added 5% of the total weight, the mortar And mixed. The material obtained by mixing is shaped into an evening bullet using a tablet press, dried, and then baked at 500 ° C for 1 hour. 7 00 and classified into m, to obtain a ZnFe ₂ 〇 ₄ / S I_〇 ₂ / MoO ₃ desulfurization agent of the present invention. Example 2

Was used in place of the M O_〇 ₃ of Example 1 to M o S ₂ were obtained in the same manner _{_{Z n F e 2 0 4 /}} S I_〇 ₂ ZMOS ₂ desulfurization agent of the present invention. Example 3

Instead the Mo_〇 ₃ of Example 1 Mo S ₂ and T i 0 _2, weight against the ZnFe _₂ 0 ₄ -S i 0 ₂ is, MoS ₂ 0.5 times, Ding 1_Rei ₂ 1.5 except for adding so as to be doubled in the same manner to obtain _{_{ZnF e 2 0 4 ZS i 0}} 2 ZMo S 2 T i 0 2 desulfurization agent of the present invention. Test example

<Desulfurization test, regeneration test and desulfurization reaction suspension test> Using the desulfurizing agents obtained in Examples 1, 2, and 3, a desulfurization test, a regeneration test, and a test for temporarily stopping the desulfurization reaction were performed using the following fixed-bed flow reactor. Reaction tube: quartz glass;

Inner diameter 7.6mm Outer diameter 10.0mm Length 40.0mm

(1) Desulfurization test conditions

Pressure Normal pressure

Temperature 450

Gas composition H ^ S concentration l O O O ppm

H ₂ 20% by volume

N _2. Balance (80% by volume)

Gas composition 2 (CH ₃ ) ₂ S concentration 100 p pm

H ₂ 20% by volume

N ₂ balance (80% by volume)

Gas flow 10 Oml / min

Desulfurizing agent sample weight 600mg

(2) Regeneration test conditions

Pressure Normal pressure

450. C

Gas composition 3 Oxidation regeneration (60 minutes)

〇 ₂ 2% by volume

N ₂ 98% by volume

Gas flow 100 m1 / min

Desulfurizer sample weight 600 mg (3) Desulfurization reaction suspension test conditions

Pressure Normal pressure

Temperature 450

Gas composition 2 (desulfurization reaction: once 60 minutes)

(CH ₃ ) ₂ S concentration 100 p pm

H ₂ 20% by volume

N ₂ balance (80% by volume)

Gas composition 4 (pause: once for 5 minutes)

N ₂ 100% by volume

Gas flow 100 m 1 Z min

Desulfurizer sample weight 600mg Test Example 1 (Gas composition 1; ^ S)

The desulfurizing agent obtained in Example 1 and Example 2 was desulfurized under the above desulfurization conditions (desulfurization temperature: 450, desulfurization gas composition 1; H ₂ S), and then oxidized and regenerated under the above regeneration conditions and repeated. A desulfurization test was carried out, and the H ₂ S concentration at the outlet of the fixed-bed flow reactor tube was measured with a gas chromatograph (device number: G2800-FPD, manufactured by Yanagimoto Seisakusho) having an FPD detector. The results are shown in FIGS. 1 and 2, respectively. Further, FIG. 3 shows a partially enlarged precise measurement of FIG. 2 (? 1 ₂ 3 the concentration of scale Ichiru 1) 111 13 obtained by changing the).

Fig. 4 shows the relationship between the number of desulfurization cycles of the desulfurizing agent of Example 1 and the amount of absorbed hydrogen sulfide, and Fig. 5 shows the relationship between the number of desulfurization cycles of the desulfurizing agent of Example 2 and the amount of absorbed hydrogen sulfide. Show the person in charge. The experimental values are based on the area of the graphs in Figs. 1 and 2 (Fig. Theoretical absorption values were calculated on the assumption ZnFe ₂ 〇 ₄ 3 mol, Fe ₂ 〇 ₃ 2 moles, 211_Rei and absorbs 1 mol of 1 ^ ₂ S.

In _{_{particular, Z n F e 2 0 4}} / S I_〇 _₂ ZMo S ₂ and _{_{Z nF e 2 0 4 / S}} i 0 2 / Mo0 3 based desulfurizing agent, H ₂ S absorption capacity and aspects superior to desulfurizing agent With each increase in the number of desulfurization regeneration treatments, the measured H ₂ S absorption value becomes higher than the theoretical value, and it can be seen that the high-performance desulfurization maintenance time of 1 ppm or less is longer.

This indicates that the desulfurizing agents of the present invention obtained in Example 1 and Example 2 have more and more excellent desulfurization performance even after the regeneration treatment.

The desulfurization agent of Example 1 and Example 2 were able to maintain excellent desulfurization performance after regeneration, the binding of zinc ferrite and silica as described above is stabilized by Mo 0 ₃ and Mo S _2, zinc ferrite It is considered that the aggregation of was prevented.

In addition, the measured H ₂ S absorption value was higher than the theoretical value.This result indicates that in addition to the desulfurization reaction formula 1 conventionally assumed as the desulfurization reaction mechanism, the desulfurization reaction as shown in reaction formula 2 is also performed. It is considered to indicate that

Reaction formula 1

ZnFe ₂ 0 ₄ + 3H ₂ S + H ₂

→ ZnS + 2Fe S + 4H ₂₀

Reaction formula 2

_{_{_{ZnF e 2 0 4 + 4H 2}}} S

→ ZnS + Fe S + Fe S ₂ + 4H ₂₀

According to Fig. 3, although the desulfurization performance is slightly inferior in the first run, the desulfurization performance in the second and subsequent runs after repeated desulfurization regeneration is as low as 3 O ppb or less for sulfur compounds. It turns out that it becomes possible. Test Example 2 (Gas composition 2; (CHJ ₉ S)

A desulfurization test and regeneration test were performed in the same manner as in Test Example 1 except that the desulfurizing agent was changed to the desulfurizing agent obtained in Example 2 and the desulfurizing gas composition was changed to desulfurizing gas composition 2; (CH ₃ ) ₂ S. I did it. At the outlet of the reaction tube, H ₂ S concentration and CH ₄ concentration were measured. The results are shown in FIGS. 6 and 7, respectively.

From Fig. 6, it is possible to desulfurize dimethyl sulfide to 100 ppb or less, and from Fig. 6, it can be seen that hydrogen sulfide generated by decomposition of dimethyl sulfate is also desulfurized to 100 ppb or less immediately. Understand. This is evident from the fact that methane generated when sulphide dimethyl is decomposed is detected (Fig. 7).

Furthermore, it takes about 40 minutes from the start of desulfurization for the dimethyl sulfide concentration to be 100 ppb or less. Therefore, the desulfurizing agent of the present invention is not modified until it undergoes catalytic denaturation with hydrogen sulfide. It is considered that the S bond can be cleaved with high efficiency.

Next, the desulfurization agent obtained in Example 3 was subjected to a desulfurization test, a regeneration test, and a desulfurization reaction suspension test. Test Example 3 (Gas composition 1; H ₉ S)

A desulfurization test and a regeneration test were performed in the same manner as in Test Example 1 except that the desulfurizing agent was replaced with the desulfurizing agent obtained in Example 3. Fig. 8 shows the results.

FIG. 8 shows the scale of the H ₂ S concentration in ppb, as in FIG. 3, and the minimum H ₂ S concentration in Example 3 was set at 100% in the same manner as in Examples 1 and 2. It is possible to reduce to ppb. Test Example 4 (Gas composition 2; (CH,), S) A desulfurization test and a regeneration test were performed in the same manner as in Test Example 2 except that the desulfurizing agent was replaced with the desulfurizing agent obtained in Example 3. The results are shown in FIGS. 9 and 10, respectively.

From Figs. 9 and 10, dimethyl sulfide was less than 3 ppm after 5 minutes from the start of desulfurization, and was hardly detected after 15 minutes.On the other hand, methane generated by decomposition of dimethyl sulfide was 15 minutes. After that, almost 200 ppm was quantitatively detected. Also, H ₂ S becomes less than 200 ρpb after 10 to 20 minutes. _{_{These, ZnFe 2 0 4 / S i}} 0 2 / MoS 2 ZT i 0 2 of Example 3 from ZnFe ₂ 0 ₄ / S I_〇 ₂ ZMOS ₂ of Example 2, after the start of desulfurization, in a very short period of time It is understood that the sulfuric acid dimethyl is effectively desulfurized. Test Example 5 (temporary suspension test for desulfurization reaction)

Using the desulfurizing agent of Example 3, a desulfurization reaction suspension test was performed. In the desulfurization reaction suspension test, the desulfurization gas composition was desulfurized with gas composition 2; (CH ₃ ) ₂ S for 60 minutes, and then gas composition 4; N ₂ was flowed for 5 minutes, and it was in the reaction tube. The desulfurization reaction was temporarily stopped by flowing out dimethyl sulfide, and then the desulfurization gas composition was changed to gas composition 2 again, and the desulfurization reaction was further performed for 60 minutes. Thereafter, the suspension and the desulfurization reaction were repeated in the same manner.

The results are shown in FIGS.

According to Figs. 11 and 12, when the desulfurization reaction is temporarily stopped and then desulfurized again, the desulfurization reaction is in a steady state immediately after the start of desulfurization, and the desulfurization is performed efficiently. Accordingly, it can be understood that the desulfurizing agent of the present invention can be used intermittently in which a temporary stop and re-reaction are repeated in a desulfurization reaction, and exhibits excellent desulfurization performance. The desulfurizing agent used in this experiment was the one used in the oxidation regeneration experiment (Figs. 9 and 10). Dimethyl sulfide is detected in a small amount 5 minutes after the start of the first desulfurization, but 15 minutes After that, it was not detected, and it was not detected at all after the second time (detection limit: 3 O ppb). On the other hand, H ₂ S is less than 100 ppb after 15 minutes from the start of the first desulfurization, and is about 30 ppb immediately after the start of the desulfurization in the third time. Industrial applicability

The desulfurizing agent of the present invention is a high-performance desulfurizing agent capable of repetitive desulfurization regeneration. By using such a desulfurizing agent, it is possible to highly efficiently remove a sulfur content in a sulfur-containing compound and perform a reforming treatment. As a result, high-purity hydrogen and highly desulfurized hydrogen can be easily produced economically. Therefore, even in fields where the allowable sulfide concentration in hydrogen gas is extremely severe, such as in phosphoric acid fuel cells and polymer electrolyte fuel cells, where electrodes and catalysts are liable to degrade due to reaction with hydrogen sulfide, etc. It can be used effectively.

Further, the method for producing a desulfurizing agent of the present invention enables the desulfurizing agent of the present invention to be produced economically and efficiently.

The desulfurization method using the desulfurizing agent of the present invention can remove sulfur components in a sulfur-containing compound with high efficiency and at a level of 100 ppb or less, such as natural gas, city gas, and LP gas. From this, the sulfur concentration can be reduced to a level of 30 ppb or less. In addition, this desulfurization method can provide excellent desulfurization performance, such as a short desulfurization start time and intermittent use in which desulfurization reaction is temporarily stopped and re-desulfurization reaction is repeated. That is, starting and stopping of desulfurization can be easily performed.

The “oxidation regeneration method” enables the desulfurization agent to be oxidized when the desulfurization performance of the desulfurization agent is reduced, thereby allowing the desulfurization agent to regenerate its desulfurization performance to the initial state.

In addition, the “temporary desulfurization reaction suspension method” is used to instantaneously perform advanced desulfurization of substances to be desulfurized. The desulfurization can be easily stopped. After the suspension of the desulfurization reaction (processing), when the next substance to be desulfurized arrives, the advanced desulfurization can be performed again immediately. During the suspension of the desulfurization reaction, safety can be ensured by replacing the desulfurization unit with nitrogen.

Furthermore, the desulfurizing agent of the present invention is used to highly efficiently remove the sulfur content of the sulfur-containing compound and perform a reforming treatment, thereby reducing a large amount of high-purity hydrogen for fuel cells and highly desulfurized hydrogen. Enables production at low cost.

Claims

The scope of the claims

1-the following general formula:

ZnFe ₂ 0 ₄ Si 0 ₂ / molybdenum compound

(Wherein, the molybdenum compound represents Mo S ₂ and Z or Mo O 3).

2. The following general formula:

ZnFe ₂ 0 ₄ / S I_〇 ₂ molybdenum compound / titanium compound '

(Wherein, the molybdenum compound, a Mo S ₂ and Z or MO0 _3, also titanium compounds show T i 0 ₂₎ desulfurizing agent which comprises a compound represented by.

3. In producing the desulfurizing agent in the range paragraph 1 or 2, wherein according to the following equation: zinc ferrite silica represented by _{_{ZnFe 2 0 4 / S i 0}} 2, molybdenum compounds (molybdenum compound shows Mo S ₂ and Z or Mo_〇 _3), or molybdenum compound and a titanium compound (titanium compound, T I_〇 shows a ₂₎ and the pulverized mixture was added, the resulting mixture into a molding aid A method for producing a desulfurizing agent, characterized by adding and baking.

4. A method for desulfurizing a sulfur-containing compound, which comprises desulfurizing the sulfur-containing compound by bringing the desulfurizing agent according to claim 1 into contact with the sulfur-containing compound.

5. The desulfurization method according to claim 4, wherein the used desulfurizing agent is regenerated by oxidizing, and the regenerated desulfurizing agent is used repeatedly.

6. The desulfurization method according to claim 4, wherein the contact between the desulfurizing agent and the sulfur-containing compound is temporarily stopped, and then the desulfurizing agent is contacted with the sulfur-containing compound again. 徵 Desulfurization method for sulfur compounds.

7. Hydrogen for fuel cells, characterized by subjecting the sulfur-containing compound to desulfurization according to claim 1 or 2 to desulfurize the sulfur-containing compound and then subjecting the sulfur-containing compound to reforming treatment. Production method.