JP4961102B2 - Method for producing zeolite and adsorbent for removing sulfur compound containing the zeolite - Google Patents

Description

  The present invention relates to a method for producing a silver ion exchanged zeolite with less destruction of zeolite crystals, an adsorbent for removing a sulfur compound containing the silver ion exchanged zeolite, and a hydrocarbon fuel or dimethyl ether fuel desulfurized using the adsorbent. The present invention relates to a method for effectively producing hydrogen usable for a fuel cell and a fuel cell system using the hydrogen.

In recent years, new energy technology has attracted attention due to environmental problems, and fuel cells are attracting attention as one of the new energy technologies.
This fuel cell converts chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen, and has a feature of high energy use efficiency. Or, practical research has been actively conducted for automobiles.
For this fuel cell, types such as a phosphoric acid type, a molten carbonate type, a solid oxide type, and a solid polymer type are known depending on the type of electrolyte used.
On the other hand, as a hydrogen source, liquefied natural gas mainly composed of methanol and methane, city gas mainly composed of this natural gas, synthetic liquid fuel using natural gas as a raw material, and petroleum-based systems such as LPG, naphtha and kerosene The use of hydrocarbons has been studied.

When producing hydrogen using these gaseous or liquid hydrocarbons, generally, there is a method of treating the hydrocarbons by partial oxidation reforming, autothermal reforming or steam reforming in the presence of a reforming catalyst. It is used.
When reforming hydrocarbon fuels such as LPG, city gas, and kerosene to produce hydrogen for fuel, the sulfur content in the fuel is reduced to 0.1 ppm or less in order to suppress poisoning of the reforming catalyst. Is required.
Further, when propylene, butene, etc. are used as a raw material for petrochemical products, the sulfur content is required to be reduced to 0.1 ppm or less in order to prevent poisoning of the catalyst.
In the LPG, dimethyl sulfide (DMS), 2-methyl-2-propanethiol (MPT), methyl added as a odorant in addition to methanethiol, carbonyl sulfide (COS) or the like as a sulfur compound. Ethyl sulfide and the like are included.
Recently, a plan to use dimethyl ether as a fuel is underway.
Although this dimethyl ether itself does not contain a sulfur compound, the addition of the above odorant has been studied intentionally in order to prevent leakage.

Various adsorbents that adsorb and remove sulfur compounds in hydrocarbon fuels such as LPG and city gas are known, but conventional adsorbents do not have sufficient adsorption capacity and need to be replaced frequently for long-term use. is there.
For example, as a sulfur compound removing adsorbent, a zeolite-based desulfurization agent in which polyvalent metal ions other than alkaline earth metals (Mn, Fe, Co, Ni, Cu, Sn, and Zn) are exchanged (see, for example, Patent Document 1) A desulfurization agent (for example, see Patent Document 2) in which Ag, Cu, Zn, Fe, Co, Ni, etc. are supported on a hydrophobic zeolite by ion exchange, or Ag or Cu on Y-type zeolite, β-zeolite or X-type zeolite. A desulfurizing agent supporting slag (see, for example, Patent Document 3) is disclosed.
All of these desulfurizing agents are described as performing ion exchange using nitrate, acetate, and chloride.
However, when ion exchange is performed by such a method, it is actually difficult to sufficiently increase the loading amount by one ion exchange.
Therefore, it is necessary to repeatedly perform ion exchange in order to increase the loading amount, and even if a metal-exchanged zeolite having a large loading amount is prepared in this manner, the adsorption performance of the sulfur compound is not sufficient.
Moreover, the desulfurization agent (for example, refer patent document 4) containing the metal ion exchange zeolite manufactured using the solution containing a metal ammine complex ion is disclosed.
However, in this method, if an attempt is made to increase the supported amount of Ag to 5% by mass or more in order to improve the performance of the desulfurizing agent, crystal destruction of the zeolite may occur, and the performance may not be sufficient.

JP-A-6-306377 JP 2001-286753 A JP 2001-305123 A JP 2004-168648 A

  The present invention has been made under such circumstances, and it can be suitably used as an adsorbent for removing sulfur compounds that can efficiently remove sulfur compounds in hydrocarbon fuels or dimethyl ether fuels to a low concentration even at room temperature. A method for producing ion exchange zeolite, an adsorbent for removing a sulfur compound containing the silver ion exchange zeolite, and a hydrogen fuel usable for a fuel cell from a hydrocarbon fuel or dimethyl ether fuel desulfurized using the adsorbent are effectively used. It is an object of the present invention to provide a method for producing the fuel cell and a fuel cell system using the hydrogen.

As a result of intensive studies to achieve the above object, the inventors of the present invention use a solution containing silver ammine complex ions, and a zeolite ion-exchanged at pH 4 to 9 has a silver metal loading in one operation. And has a high adsorption performance for sulfur compounds compared to a silver ion-supported zeolite desulfurization agent obtained at a pH of more than 9, and there is little crystal destruction of the zeolite. It has been found that hydrogen that can be used for fuel cells can be effectively obtained by reforming the hydrocarbon fuel or dimethyl ether fuel desulfurized using the same.
The present invention has been completed based on such findings.

That is, the present invention
1. A method for producing a silver ion-exchanged zeolite, comprising using a solution containing silver ammine complex ions and carrying silver by an ion exchange method at a pH of 4 to 9,
2. The method for producing a silver ion-exchanged zeolite according to 1 above, wherein the silver ammine complex ion is prepared using ammonia and / or ammonium nitrate,
3. The method for producing a silver ion-exchanged zeolite according to 1 or 2 above, wherein the zeolite is at least one selected from HY type and USY type zeolites and β zeolites,
4). The method for producing a silver ion-exchanged zeolite according to any one of the above 1 to 3, wherein the silver loading is 5 to 30% by mass as silver metal,
5. The method for producing a silver ion-exchanged zeolite according to any one of the above 1 to 4, wherein the zeolite is a molded zeolite,
6). An adsorbent comprising the silver ion-exchanged zeolite obtained by the method according to any one of 1 to 5 above,
7). A catalyst comprising the silver ion-exchanged zeolite obtained by the method according to any one of 1 to 5 above,
8). An adsorbent for removing a sulfur compound in a hydrocarbon fuel or dimethyl ether fuel, comprising the silver ion-exchanged zeolite obtained by the method according to any one of 1 to 5 above.
9. 9. The sulfur compound removal according to 8 above, wherein the hydrocarbon fuel is at least one hydrocarbon compound selected from LPG, city gas, natural gas, naphtha, kerosene, light oil or ethane, ethylene, propane, propylene, butane and butene. Adsorbent,
10. After the sulfur compound in the hydrocarbon fuel or dimethyl ether fuel is desulfurized using the sulfur compound removing adsorbent according to 8 or 9, the desulfurized fuel is used as a partial oxidation reforming catalyst, an autothermal reforming catalyst, or A method for producing hydrogen, characterized by contacting with a steam reforming catalyst;
11. The method for producing hydrogen according to 10 above, wherein the partial oxidation reforming catalyst, autothermal reforming catalyst or steam reforming catalyst is a ruthenium-based or nickel-based catalyst,
12 The present invention provides a fuel cell system using hydrogen produced by the method described in 10 or 11 above.

  According to the present invention, a silver ion-exchanged zeolite that has been subjected to silver ion exchange at a pH of 5 to 9 using a solution containing silver ammine complex ions has little destruction of zeolite crystals even when the silver loading is 5% by mass or more. The adsorbent containing exchanged zeolite can remove sulfur compounds very efficiently even at room temperature.

The method for producing a silver ion-exchanged zeolite of the present invention is a method in which a silver metal exchange is performed at pH 4 to 9 using a solution containing silver ammine complex ions and the silver metal is supported on the zeolite.
In the present invention, as the zeolite, at least one selected from those having FAU, BEA, MOR, MTW, GME, OFF, MFI, MEL, FER, TON, and LTA structures can be used.
Among these, zeolites having FAU and BEA structures are preferred, and HY type and USY type zeolites are particularly preferred as FAU structures, and β zeolite is preferred as a BEA structure from the viewpoint of adsorption performance.
Hereinafter, the manufacturing method of a silver ion exchange zeolite is demonstrated.
As a solution containing silver ammine complex ions, a solution in which water-soluble silver ammine complex ions are dissolved in water or a silver compound such as silver nitrate, silver carbonate, silver acetate, silver sulfate and silver chloride is dissolved in water. An excess of aqueous ammonia can be added to or dissolved in aqueous ammonia to form a silver ammine complex ion.
In addition, ammonium nitrate, urea, amines and the like can be added in the formation of silver ammine complex ions.
In particular, ammonia and / or ammonium nitrate is preferably used.

In order to prepare the silver ion exchanged zeolite in the present invention, first, zeolite is added to a solution containing silver ammine complex ions and stirred, and if necessary, ammonia or amine or the like, and nitric acid is optionally added to adjust the pH to 4 to 4. The ion exchange treatment is carried out at a temperature in the range of 9 to 0 to 90 ° C., preferably 20 to 70 ° C., preferably for about 1 to several hours, preferably with stirring.
When the pH of the solution containing silver ammine complex ions is 4 or more, the supported amount of silver can be increased, and when the pH is 9 or less, the zeolite crystals are hardly broken.
Next, the solid is separated by a means such as filtration, washed with water, and then dried at a temperature of 500 ° C. or lower (preferably about 50 to 200 ° C.).
This ion exchange treatment can be repeated.
Next, the target silver ion-exchanged zeolite is obtained by firing at a temperature of 500 ° C. or less (preferably about 200 to 500 ° C.) for several hours.
The supported amount of silver in the silver ion-exchanged zeolite thus obtained is preferably in the range of 5 to 30% by mass as silver, and particularly preferably in the range of 10 to 30% by mass.
Further, the silver ion-exchanged zeolite as described above can be used after being molded by an ordinary method such as extrusion molding, tableting molding, rolling granulation, spray drying and the like using an appropriate binder.
In addition, a pre-formed zeolite can be used after performing silver ion exchange in the present method.
Zeolite is preferably molded zeolite rather than powder, and the smaller the particle size, the more preferable.

The crystallinity of the silver ion exchanged zeolite produced by the above method can be measured by X-ray diffraction, for example, by the relative intensity of the X-ray diffraction peak (XRD) of the silver ion exchanged zeolite and the untreated zeolite. Can show.
That is, since this relative strength differs depending on the size of the zeolite crystal and the exchanged metal species, it does not directly indicate the degree of crystallinity, but it can be compared for those obtained by exchanging the same metal.
Specifically, among the X-ray diffraction peaks, 3 to 10 peaks having high intensity and good separation in the main peak range (2θ = 10 to 40 °) are selected, and the average of the relative intensity of each peak is selected. Shown by value.
[Conditions for X-ray diffraction measurement]
Cu-Kα ray: wavelength λ = 1.5406Å, output: 40 kV, 40 mA
Optical system: reflection method; 2θ · θ continuous scan, DS, SS slit: 1 °
RS slit: 0.3 mm, step interval: 0.02 °, scan speed: 1 ° / min

  In addition, the silver ion exchanged zeolite produced by the above method is not only an adsorbent for removing sulfur compounds, but also the production of ethylene oxide by oxidation of ethylene, the production of formaldehyde by dehydrogenation of methanol, and the production of nitrogen oxides from exhaust gas. It is suitably used for adsorbents such as catalysts for removal, adsorption of various hydrocarbons, adsorption of hydrocarbons in automobile exhaust gas, adsorption of sulfur compounds, selective adsorption of nitrogen in the air, and the like.

The sulfur compound-removing adsorbent containing silver ion-exchanged zeolite obtained as described above is applied to hydrocarbon fuel or dimethyl ether fuel.
Here, examples of the hydrocarbon fuel include LPG, city gas, natural gas, naphtha, kerosene, light oil, or at least one hydrocarbon compound selected from ethane, ethylene, propane, propylene, butane, and butene. Can do.
The concentration of the sulfur compound in the hydrocarbon gas to which the adsorbent of the present invention is applied is preferably 0.001 to 10,000 ppm by volume, and particularly preferably 0.1 to 100 ppm by volume.
As desulfurization conditions, the temperature is usually selected in the range of −50 to 150 ° C., and the GHSV is selected in the range of 100 to 1,000,000 h ⁻¹ .
When the desulfurization temperature exceeds 150 ° C., adsorption of sulfur compounds is difficult to occur.
A preferred temperature is in the range of −50 to 120 ° C., more preferably −20 to 100 ° C.
Also preferred GHSV is 100～100,000H ^-1, more preferably from 100~50,000h ^-1.
Moreover, when using liquid fuel, the density | concentration of a sulfur compound has preferable 0.001-10,000 mass ppm, and 0.1-100 mass ppm is especially preferable.
As desulfurization conditions, the temperature is usually selected in the range of −50 to 150 ° C., and the WHSV is selected in the range of 0.1 to 1,000 h ⁻¹ .

The silver ion-exchanged zeolite of the present invention can be produced by silver ion exchange of zeolite at pH 4 to 9 using a solution containing silver ammine complex ions, and has a large amount of silver metal supported by a single ion exchange treatment. There is little crystal destruction.
Moreover, the adsorbent containing the silver ion-exchanged zeolite of the present invention is superior in desulfurization performance than the adsorbent containing silver ion-exchanged zeolite that has been subjected to silver ion exchange at a pH exceeding 9.
Next, in the method for producing hydrogen that can be used in the fuel cell of the present invention, the sulfur compound in the hydrocarbon fuel or dimethyl ether fuel is desulfurized using the adsorbent of the present invention, and then the desulfurized fuel. To produce hydrogen.

At this time, methods such as partial oxidation reforming, autothermal reforming, and steam reforming can be used as reforming methods.
In this reforming method, the concentration of the sulfur compound in the desulfurized hydrocarbon fuel or dimethyl ether fuel is preferably 0.1 ppm by volume or less, particularly preferably 0.005 ppm by volume or less, from the viewpoint of the life of each reforming catalyst. preferable.
The partial oxidation reforming is a method for producing hydrogen by a partial oxidation reaction of hydrocarbons, and in the presence of a partial oxidation reforming catalyst, usually a reaction pressure of normal pressure to 5 MPa, a reaction temperature of 400 to 1,100 ° C. The reforming reaction is carried out under the conditions of GHSV 1,000 to 100,000 h ⁻¹ and oxygen (O ₂ ) / carbon ratio 0.2 to 0.8.
Autothermal reforming is a method in which partial oxidation reforming and steam reforming are combined. In the presence of an autothermal reforming catalyst, the reaction pressure is usually from normal pressure to 5 MPa, and the reaction temperature is from 400 to 1,100. The reforming reaction is carried out under the conditions of ° C., oxygen (O ₂ ) / carbon ratio of 0.1 to 1, steam / carbon ratio of 0.1 to 10, and GHSV of 1,000 to 100,000 h ⁻¹ .
Furthermore, steam reforming is a method for producing hydrogen by bringing steam into contact with a hydrocarbon, usually in the presence of a steam reforming catalyst, at a reaction pressure of normal pressure to 3 MPa, a reaction temperature of 200 to 900 ° C., steam. The reforming reaction is performed under the conditions of / carbon ratio of 1.5 to 10 and GHSV of 1,000 to 100,000 h ⁻¹ .

In the present invention, the partial oxidation reforming catalyst, autothermal reforming catalyst, and steam reforming catalyst can be appropriately selected from conventionally known catalysts, but are particularly ruthenium-based and nickel-based. A catalyst is preferred.
Moreover, as a support | carrier of these catalysts, the support | carrier containing at least 1 type chosen from manganese oxide, a cerium oxide, and a zirconia can be mentioned preferably.
The carrier may be a carrier composed of only these metal oxides, or may be a carrier obtained by adding the above metal oxide to another refractory porous inorganic oxide such as alumina.

The present invention also provides a fuel cell system using hydrogen obtained by the production method.
The fuel cell system of the present invention will be described below with reference to FIG.
FIG. 1 is a schematic flowchart showing an example of the fuel cell system of the present invention.
According to FIG. 1, the fuel in the fuel tank 21 flows into the desulfurizer 23 via the fuel pump 22.
The desulfurizer can be filled with the adsorbent of the present invention.
The fuel desulfurized by the desulfurizer 23 is mixed with water from the water tank through the water pump 24, then introduced into the vaporizer 1, vaporized, and then mixed with the air sent out from the air blower 35 to the reformer 31. It is sent.
The reformer 31 is filled with the above-described reforming catalyst, and from the fuel mixture (mixed gas containing water vapor, oxygen and hydrocarbon fuel or oxygen-containing hydrocarbon fuel) fed into the reformer 31, Hydrogen or synthesis gas is produced by any of the reforming reactions described above.

The hydrogen or synthesis gas thus produced is reduced through the CO converter 32 and the CO selective oxidizer 33 to such an extent that the CO concentration does not affect the characteristics of the fuel cell.
Examples of the catalyst used in these reactors include an iron-chromium catalyst, a copper-zinc catalyst or a noble metal catalyst in the CO converter 32, and a ruthenium catalyst, a platinum catalyst or a noble metal catalyst in the CO selective oxidation furnace 33. The mixture etc. can be mentioned.
The fuel cell 34 is a solid polymer fuel cell having a polymer electrolyte 34C between a negative electrode 34A and a positive electrode 34B.
The hydrogen-rich gas obtained by the above method is introduced into the negative electrode side, and the air sent from the air blower 35 is introduced into the positive electrode side after performing appropriate humidification treatment as necessary (humidifier not shown). Is done.
At this time, a reaction in which hydrogen gas becomes protons and releases electrons proceeds on the negative electrode side, and a reaction in which oxygen gas obtains electrons and protons to become water proceeds on the positive electrode side, and a direct current is generated between both electrodes 34A and 34B. To do.
Platinum black, activated carbon-supported Pt catalyst or Pt-Ru alloy catalyst is used for the negative electrode, and platinum black, Pt catalyst supported on activated carbon is used for the positive electrode.

The surplus hydrogen can be used as fuel by connecting the burner 31A of the reformer 31 to the negative electrode 34A side.
Further, in the steam separator 36 connected to the positive electrode 34B side, water and exhaust gas generated by the combination of oxygen and hydrogen in the air supplied to the positive electrode 34B side are separated, and the water is used to generate water vapor. Can be used.
In the fuel cell 34, since heat is generated with power generation, an exhaust heat recovery device 37 can be attached to recover the heat for effective use.
The exhaust heat recovery device 37 includes a heat exchanger 37A that takes away the heat generated during the reaction, a heat exchanger 37B that exchanges heat taken by the heat exchanger 37A with water, a cooler 37C, and these heat exchanges. The hot water obtained in the heat exchanger 37B can be effectively used in other facilities. The pumps 37A and 37B and the pump 37D circulate the refrigerant to the cooler 37C.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Example 1
A commercially available HY-type zeolite molding (manufactured by Tosoh, HSZ-320HOD1A) was crushed to a particle size of 0.5 to 1 mm.
394 g of silver nitrate was dissolved in 2.5 L of water, and 276 g of ammonium nitrate and 220 g of 30% by mass ammonia water were added thereto to obtain a silver ammine complex ion solution.
1 kg of the zeolite was charged into the silver ammine complex ion solution.
This solution was stirred and subjected to silver ion exchange treatment for 6 hours.
The pH of the solution at this time was 6.8.
Thereafter, the solid matter was collected by filtration, washed with water, dried at 120 ° C., and further subjected to calcination treatment at 400 ° C. for 3 hours to obtain a silver ion-exchanged Y-type zeolite.
The silver content was 11.2% by mass.
X-ray diffraction measurement was performed, and X-ray diffraction intensity of untreated HY-type zeolite was measured for three peaks of Miller indices (5, 3, 3), (6, 4, 2), (5, 5, 5). When the average value was compared with (XRD), the strength ratio of this product was 65%.
The results are shown in Table 1.

Example 2
Silver ion exchange treatment was performed in the same manner as in Example 1 except that a commercially available β zeolite molded product (HSZ-930HODA manufactured by Tosoh Corp.) was used to obtain a particle size of 0.5 to 1 mm. β zeolite was obtained.
The pH of the silver ion exchange treatment was 6.0, and the silver content was 11.5% by mass.
X-ray diffraction measurement was performed, and the three peaks of Miller indices (3, 0, 2), (3, 0, 6), (2, 1, 4) When the average values were compared, the strength ratio of this product was 61%.
The results are shown in Table 1.

Comparative Example 1
In Example 1, silver ion exchange treatment was performed in the same manner as in Example 1 except that 440 g of 30% by mass of ammonia water was added without adding ammonium nitrate to obtain silver ion exchanged Y-type zeolite.
The pH of the silver ion exchange treatment was 9.6, and the silver content was 12.7% by mass.
X-ray diffraction measurement was performed, and X-ray diffraction intensity of untreated HY-type zeolite was measured for three peaks of Miller indices (5, 3, 3), (6, 4, 2), (5, 5, 5). When the average value was compared, the strength ratio of this product was 29%.
The results are shown in Table 1.

Test example 1
The silver ion exchange zeolites of Examples 1 and 2 and Comparative Example 1 were molded to 0.5 to 1 mm, and 1 cm ³ of an adsorbent was filled in a desulfurization tube having an inner diameter of 9 mm.
The adsorbent temperature is 20 ° C. at normal pressure, and propane gas containing 20 ppm by volume (total 40 ppm by volume) of dimethyl sulfide (DMS) and 2-methyl-2-propanethiol (MPT) is used at normal pressure, GHSV (gas It was made to circulate on the condition of space-time velocity 20,000h < ^-1 >.
The concentration of each sulfur compound in the desulfurization pipe outlet gas was measured every hour by SCD (Sulfur Chemiluminescence Detector) gas chromatography.
Table 1 shows the time for each sulfur compound concentration to exceed 0.1 ppm by volume.

As can be seen from a comparison between Examples 1 and 2 and Comparative Example 1, the zeolite subjected to silver ion exchange at pH 4 to 9 according to the present invention has a crystal destruction of the zeolite in contrast to the zeolite subjected to silver ion exchange at a pH exceeding 9. Few.
In addition, the silver ion-exchanged zeolite of the present invention is superior in desulfurization performance at almost the same silver loading.

It is a schematic flowchart which shows an example of the fuel cell system of this invention.

Explanation of symbols

1: Vaporizer 2: Fuel cell system 20: Hydrogen production system 21: Fuel tank 23: Desulfurizer 31: Reformer 31A: Boiler 32: CO converter 33: CO selective oxidizer 34: Fuel cell 34A: Negative electrode 34B: Cathode 34C: Polymer electrolyte 36: Steam separator 37: Waste heat recovery device 37A: Heat exchanger 37B: Heat exchanger 37C: Cooler

Claims (9)

Contains silver ammine complex ions obtained by dissolving water-soluble silver ammine complex ions in water, dissolving silver compounds in water and adding excess ammonia water thereto, or dissolving silver compounds in ammonia water A method for producing a silver ion-exchanged zeolite, comprising using a solution and carrying silver by an ion exchange method at a pH of 4 to 9.   The method for producing a silver ion-exchanged zeolite according to claim 1, wherein the silver ammine complex ion is prepared using ammonia and / or ammonium nitrate.   The method for producing a silver ion-exchanged zeolite according to claim 1 or 2, wherein the zeolite is at least one selected from HY type, USY type zeolite, and β zeolite.   The method for producing a silver ion-exchanged zeolite according to any one of claims 1 to 3, wherein the silver loading is 5 to 30% by mass as silver metal.   The method for producing a silver ion-exchanged zeolite according to any one of claims 1 to 4, wherein the zeolite is a molded zeolite.   An adsorbent for removing sulfur compounds in hydrocarbon fuel or dimethyl ether fuel, comprising the silver ion exchanged zeolite obtained by the method according to any one of claims 1 to 5.   7. The sulfur compound according to claim 6, wherein the hydrocarbon fuel is at least one hydrocarbon compound selected from LPG, city gas, natural gas, naphtha, kerosene, light oil or ethane, ethylene, propane, propylene, butane and butene. Removal adsorbent.   A sulfur compound removal adsorbent according to claim 6 or 7 is used to desulfurize a sulfur compound in a hydrocarbon fuel or dimethyl ether fuel, and the desulfurized fuel is used as a partial oxidation reforming catalyst or an autothermal reforming catalyst. Or the manufacturing method of hydrogen characterized by making it contact with a steam reforming catalyst.   The method for producing hydrogen according to claim 8, wherein the partial oxidation reforming catalyst, the autothermal reforming catalyst, or the steam reforming catalyst is a ruthenium-based or nickel-based catalyst.

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