JP2006290987A - Liquefied petroleum gas for lp gas fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a petroleum gas for an LP gas fuel cell that permits enhancement of desulfurizing effects by efficient performances of a desulfurizing agent even with a minimum use amount of the desulfurizing agent thereby preventing damages of a reforming catalyst in a reforming device for the manufacture of hydrogen arranged downstream of a desulfurizing device to permit stable operations of the reforming device and stable electric power generation. <P>SOLUTION: The liquefied petroleum gas for the LP gas fuel cell comprises at most 3 vol% of 2C hydrocarbon compounds and at most 3 vol% of 4C hydrocarbon compounds and has a total sulfur concentration of at most 10 mass ppm and a sulfur content originating from methyl mercaptan of at most 3 mass ppm, the rest being 3C hydrocarbon compounds. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquefied petroleum gas fuel suitable for an LP gas fuel cell system and a desulfurization method thereof.

  In recent years, due to the growing sense of crisis for the global environment in the future, development of an energy supply system that is friendly to the earth has been demanded. From the viewpoint of high energy efficiency and clean exhaust gas, fuel such as fuel cells and hydrogen engines can be used as fuel. The system is in the limelight. In particular, as a method of supplying hydrogen to the fuel cell, in addition to a method of directly supplying hydrogen in the form of compression or liquefaction, a supply method by reforming of an oxygen-containing fuel such as methanol and a hydrocarbon-based fuel such as naphtha. Is known (for example, see Non-Patent Document 1). Among these, the method of directly supplying hydrogen has an advantage that it can be used as a fuel as it is, but it has a problem in storability and mountability when used in a vehicle or the like because it is a gas at room temperature. On the other hand, the production of hydrogen by reforming hydrocarbon fuels such as liquefied petroleum gas has attracted attention due to the fact that the existing fuel supply infrastructure can be used and the total energy efficiency is high.

In Patent Document 1, as a fuel for a fuel cell system, isoparaffin in a saturated component having a saturated component of 60 mol% or more, an olefin component of 40 mol% or less, a butadiene component of 0.5 mol% or less, and a carbon number of 4 or more is disclosed. There is disclosed a fuel for a fuel cell system comprising a hydrocarbon compound that is 0.1 mol% or more and is a gas at normal temperature.
In addition, the properties of liquefied petroleum gas used as household fuel are usually 80% or more by volume of hydrocarbon compounds having 3 carbon atoms, 5% by volume or less of hydrocarbon compounds having 2 carbon atoms, and carbon number. The content of the hydrocarbon compound 4 is 25% by volume or less. In the liquefied petroleum gas fuel, various sulfur compounds are usually contained in several ppm to several tens of ppm. Moreover, when liquefied petroleum gas is supplied by a natural vaporization supply system, as the amount of liquefied petroleum gas in the cylinder increases, the sulfur concentration in the supplied liquefied petroleum gas increases, and the supplied fuel gas is heavy. The number of hydrocarbon compounds increases. For this reason, the amount of hydrogen generated in the reformer is reduced, and an operation for increasing the gas supply amount to the fuel cell is necessary to obtain necessary power, which hinders stable operation. In addition, sulfur compounds need to be removed because they become catalyst poisons for the catalysts charged in the reformers intended for hydrogen production for fuel cells or the catalysts used in fuel cells. In general, a desulfurizer filled with a desulfurization agent for removing sulfur compounds in the fuel gas is installed upstream of the reformer. Focusing on the performance of LP gas fuel cells, the current situation is that almost no investigation has been made on the composition of liquefied petroleum gas suitable for LP gas fuel cells.

Masaki Ikematsu, “Engine Technology”, Sankai-do Co., Ltd., January 2001, Vol. 3, No. 1, p. 35 International Publication No. 02/000813 Pamphlet

  The present invention has been made in view of such a situation, and even when a minimum amount of a desulfurizing agent is used, the desulfurizing agent functions efficiently, the desulfurizing effect is improved, and hydrogen production is arranged downstream from the desulfurizer. An object of the present invention is to provide a liquefied petroleum gas for a fuel cell and a desulfurization method thereof that can prevent damage to the reforming catalyst in the reformer for use, and can stably operate the reformer and generate stable power. To do.

As a result of intensive studies to achieve the above object, the present inventors have found that liquefied petroleum gas having a specific composition can solve the above problems, and have completed the present invention based on this finding.
That is, the present invention
(1) The content of hydrocarbon compound having 2 carbon atoms is 3% by volume or less, the content of hydrocarbon compound having 4 carbon atoms is 3% by volume or less, the total sulfur concentration is 10 mass ppm or less, and the sulfur concentration of methyl mercaptan Is a liquefied petroleum gas for LP gas fuel cells, comprising 3 ppm by mass or less and the balance comprising a hydrocarbon compound having 3 carbon atoms,
(2) The liquefied petroleum gas for LP gas fuel cells according to (1) above, wherein the sulfur concentration of methyl mercaptan is 2 mass ppm or less,
(3) The liquefied petroleum gas for LP gas fuel cells according to (2), wherein the total sulfur concentration is 7 mass ppm or less and the sulfur concentration of methyl mercaptan is 2 mass ppm or less,
(4) The liquefied petroleum gas for an LP gas fuel cell according to (3), wherein the total sulfur concentration is 5 mass ppm or less and the sulfur concentration of methyl mercaptan is 2 mass ppm or less,
(5) A desulfurization method, wherein the liquefied petroleum gas for an LP gas fuel cell according to any one of (1) to (4) above is naturally vaporized and then desulfurized using a desulfurizing agent.
(6) The desulfurization method according to (5), wherein the desulfurization agent is a desulfurization agent containing zeolite and / or a desulfurization agent composed of at least one selected from metal elements, metal oxides, and metal component-supported oxides,
(7) The desulfurization agent containing zeolite is together with zeolite, Ag component, Cu component, Ni component, Zn component, Mn component, Fe component, Co component, Si component, Al component, alkali metal component, alkaline earth metal component, and The desulfurization method according to (6) above, which comprises at least one metal component selected from the group consisting of rare earth metal components,
(8) The desulfurization method according to the above (6) or (7), wherein the zeolite has a beta (BEA) and / or faujasite (FAU) structure,
(9) A desulfurization agent comprising at least one selected from metal elements, metal oxides and metal component-supported oxides is an Ag component, a Cu component, a Ni component, a Zn component, a Mn component, an Fe component, a Co component, Si The desulfurization method according to (6) above, comprising at least one metal component selected from the group consisting of a component, an Al component, an alkali metal component, an alkaline earth metal component, and a rare earth metal component,
It is.

  According to the present invention, the desulfurization agent in the desulfurizer functions efficiently even with the use of a minimum desulfurization agent, the desulfurization effect is improved, and the reformer for hydrogen production disposed downstream from the desulfurizer is used. It is possible to provide a liquefied petroleum gas for a LP gas fuel cell and a desulfurization method that can prevent damage to the reforming catalyst and enable stable operation of the reformer and stable power generation.

Hereinafter, the present invention will be described in more detail.
In the present invention, the liquefied petroleum gas used as fuel has a content of hydrocarbon compound having 2 carbon atoms of 3% by volume or less, a content of hydrocarbon compound of 4 carbon atoms of 3% by volume or less, and a total sulfur concentration of 10%. This is a liquefied petroleum gas for an LP gas fuel cell comprising a mass ppm or less, a sulfur concentration of methyl mercaptan of 3 mass ppm or less, and the balance comprising a hydrocarbon compound having 3 carbon atoms.

The hydrocarbon compound having 3 carbon atoms is a paraffin and / or olefin having 3 carbon atoms, and the hydrocarbon compound having 2 carbon atoms is also a paraffin and / or olefin having 2 carbon atoms. The hydrocarbon compound having 4 carbon atoms is at least one hydrocarbon compound selected from paraffins, olefins and diolefins having 4 carbon atoms.
When the content of the hydrocarbon compound having 3 carbon atoms is preferably 96% by volume or more and less than 96% by volume, when such a liquefied petroleum gas is used as a hydrogen raw material for a fuel cell in a vaporization supply system, The composition fluctuation of the hydrocarbon compound becomes large, and it may be difficult to adjust the supply amount of the fuel gas corresponding to the predetermined power amount. Further, when steam is added during reforming, the steam / carbon ratio may fluctuate and the operation of the reformer may become unstable.
When the content of hydrocarbon compounds having 4 carbon atoms exceeds 3% by volume, when such liquefied petroleum gas is used as a hydrogen raw material for fuel cells in the vaporization supply system, the composition of hydrocarbon compounds having 4 carbon atoms is used at the end of the cylinder use. May increase, and hydrogen may not be generated enough to obtain a predetermined power in the reformer.
The composition for each carbon number is measured by the analysis method described in JIS K2240 “Liquefied petroleum gas 5.9 composition analysis method”.

The total sulfur concentration in the liquefied petroleum gas of the present invention is 10 mass ppm or less, preferably 7 mass ppm or less, more preferably 5 mass ppm or less. If the total sulfur concentration exceeds 10 ppm by mass, the amount of desulfurizing agent used will increase and the size of the desulfurizer will become excessively large, which will be restricted by the size of the fuel cell system itself and will be economically disadvantageous. Become.
The sulfur concentration of methyl mercaptan is 3 ppm by mass or less, preferably 2 ppm by mass or less. If it exceeds 3 mass ppm, the influence on the desulfurizing agent is large, and as a result, the amount of the desulfurizing agent to be used is increased, and the size of the fuel cell system itself is restricted, and this is economically disadvantageous.
The sulfur concentration is measured by a gas chromatography method equipped with an SCD detector (Sulfur Chemiluminescence Detector). For example, the measurement is performed under the following conditions. Separation column: DB-1, length: 60 m, membrane pressure: 5 μm, ID: 0.32 mm, split ratio: 1: 5, carrier gas: helium, flow rate: 23 ml / min, temperature: held at 40 ° C. for 4 minutes The temperature is raised to 200 ° C. at 10 ° C./min and held at 200 ° C. for 15 minutes.

  The type of the fuel cell using the liquefied petroleum gas of the present invention is not particularly limited, and examples thereof include a solid oxide fuel cell (SOFC), a solid polymer fuel cell (PEFC), and a phosphoric acid fuel cell (PAFC). The present invention is applicable to any fuel cell such as a molten carbonate fuel cell (MCFC).

  There is no restriction | limiting in particular about the manufacturing method of liquefied petroleum gas. For example, there are a method in which gas components produced as a by-product from oil fields and natural gas fields are refined and compressed, and a method in which crude oil is refined. In the process of refining crude oil, liquefied petroleum gas components obtained from crude oil atmospheric distillation equipment and liquefied petroleum gas components obtained from naphtha catalytic reforming equipment, catalytic cracking equipment, hydrocracking equipment, hydrodesulfurization equipment, etc. are distilled and separated. Thereafter, the sulfur component is removed and further liquefied and separated to obtain liquefied petroleum gas at the primary base of desired purity. The removal of the sulfur component is performed by a method appropriately selected from hydrodesulfurization, soda cleaning, amine cleaning, and Marlox.

  Usually, in liquefied petroleum gas used as fuel for fuel cells, a small amount of sulfur component not removed in the crude oil refining process and sulfur component added as odorant, for example, mercaptans such as methyl mercaptan, carbonyl sulfide And sulfur compounds such as hydrogen sulfide, sulfides, disulfide, thiophene and hydrothiophenes. When hydrogen for fuel cells is produced by reforming liquefied petroleum gas, it is required to reduce these sulfur compounds as much as possible in order to prevent poisoning of the catalyst as described above. Therefore, the liquefied petroleum gas desulfurization treatment of the present invention is performed using a conventionally known desulfurization agent. One kind of desulfurization agent may be used, or a combination of desulfurization agents having different adsorption characteristics for each sulfur compound may be used. In order to maximize performance, it is desirable to use liquefied petroleum gas or the like having as low a sulfur content as possible.

In the desulfurization method of the present invention, the liquefied petroleum gas is desulfurized using a desulfurizing agent. As this desulfurization agent, a desulfurization agent containing zeolite and / or a desulfurization agent composed of at least one selected from metal elements, metal oxides and metal component-supported oxides is preferable.
The desulfurizing agent containing the zeolite (hereinafter sometimes referred to as desulfurizing agent A) is not particularly limited, and conventionally known desulfurizing agents can be used. As the desulfurizing agent A, for example, using a zeolite combined with one or more of β-type, X-type, Y-type zeolite, etc. as a carrier, Ag component, Cu component, Ni component, Zn component, Mn component, Examples thereof include those carrying at least one metal component selected from an Fe component, a Co component, an alkali metal component, an alkaline earth metal component, and a rare earth metal component. Here, preferred examples of the alkali metal component include potassium and sodium, examples of the alkaline earth metal component include calcium and magnesium, and examples of the rare earth metal component include lanthanum and cerium. Among these metal components, an Ag component and / or a Cu component are particularly preferable.

The desulfurizing agent A can be prepared by supporting the metal component on the zeolite. Specifically, an aqueous solution containing a water-soluble compound of the target metal component is brought into contact with the zeolite by a stirring method, an impregnation method, a distribution method, etc., and then appropriately washed with water and then dried and fired. Is obtained.
The content of the metal component in the desulfurizing agent A thus obtained is usually 1 to 40% by mass, preferably 5 to 30% by mass as the metal element.

A desulfurization agent comprising at least one selected from metal elements, metal oxides and metal component-supported oxides (hereinafter sometimes referred to as desulfurization agent B) is an Ag component, a Cu component, a Ni component, a Zn component, or a Mn component. Preferable examples include those carrying at least one metal component selected from among Fe component, Co component, Si component, Al component, alkali metal component, alkaline earth metal component and rare earth metal component. Here, preferred examples of the alkali metal component include potassium and sodium, examples of the alkaline earth metal component include calcium and magnesium, and examples of the rare earth metal component include lanthanum and cerium.
The desulfurization agent B is preferably a porous inorganic oxide support on which each of the above metal components is supported, and in particular, one in which at least one of an Ag component, a Cu component, a Ni component, and a cerium component is supported is preferable. . Each metal component can be supported by a normal supporting method such as a coprecipitation method or an impregnation method.

Examples of the porous inorganic oxide support include at least one selected from silica, alumina, silica-alumina, titania, zirconia, magnesia, ceria, diatomaceous earth, clay, clay, or zinc oxide, and among these, the alumina support A silica-alumina support is preferred.
Below, the preparation method of the Ni-Cu type | system | group desulfurization agent which uses the suitable silica alumina as a support | carrier as this desulfurization agent B is demonstrated.
In the desulfurizing agent B, from the viewpoint of desulfurization performance and mechanical strength of the desulfurizing agent, the supported total metal content (as oxide) is usually 5 to 90% by mass, and the support is 95 to 10% by mass. The range is preferable, and the total metal content (as oxide) is 40 to 90% by mass, more preferably 70 to 90% by mass when supported by the coprecipitation method, and 5 to 5 when supported by the impregnation method. It is preferable that it is 40 mass%.
First, an acidic aqueous solution or aqueous dispersion containing a nickel source, a copper source and an aluminum source, and a basic aqueous solution containing a silicon source and an inorganic base are prepared. Examples of the nickel source used in the former acidic aqueous solution or aqueous dispersion include nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, nickel carbonate and hydrates thereof, and examples of the copper source include copper chloride, Examples thereof include copper nitrate, copper sulfate, copper acetate, and hydrates thereof. These nickel sources and copper sources may be used alone or in combination of two or more.

  Examples of the aluminum source include hydrated alumina such as pseudo boehmite, boehmite alumina, bayerite, and gypsite, and γ-alumina. Among these, pseudo boehmite, boehmite alumina, and γ-alumina are preferable. These can be used in the form of powder or sol. Moreover, this aluminum source may be used alone or in combination of two or more.

On the other hand, the silicon source used in the basic aqueous solution is not particularly limited as long as it is soluble in an alkaline aqueous solution and becomes silica upon firing. For example, orthosilicic acid, metasilicic acid, and their sodium salts A potassium salt, water glass, etc. are mentioned. These may be used singly or in combination of two or more, but water glass which is a kind of sodium silicate hydrate is particularly suitable.
The inorganic base is preferably an alkali metal carbonate or hydroxide, and examples thereof include sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide. These may be used alone or in combination of two or more, but sodium carbonate alone or a combination of sodium carbonate and sodium hydroxide is particularly suitable. The amount of the inorganic base used is advantageously selected so that, when the acidic aqueous solution or aqueous dispersion and the basic aqueous solution are mixed in the next step, the mixed solution is substantially neutral to base. .
In addition, the inorganic base may be used in the total amount for the preparation of the basic aqueous solution, or a part thereof may be added to the acidic aqueous solution or the mixture of the aqueous dispersion and the basic aqueous solution in the next step. May be.

The acidic aqueous solution or aqueous dispersion thus prepared and the basic aqueous solution are each heated to about 50 to 90 ° C., and then both are mixed. After mixing, if necessary, an aqueous solution containing an inorganic base heated to 50 to 90 ° C. is further added, and the mixture is stirred at a temperature of about 50 to 90 ° C. for about 0.5 to 3 hours to react. To complete.
Next, the produced solid is sufficiently washed and separated into solid and liquid, or the produced solid is separated into solid and liquid and then washed sufficiently, and then this solid is obtained at a temperature of about 80 to 150 ° C. by a known method. Dry at a temperature of The dried product thus obtained is preferably fired at a temperature in the range of 200 to 400 ° C. to obtain a desulfurizing agent B in which nickel and copper are supported on a support. When the firing temperature is out of the above range, it is difficult to obtain a Ni—Cu desulfurizing agent having desired performance.

Next, a method for preparing a silver-supported desulfurizing agent using alumina as a carrier suitable as the desulfurizing agent B will be described.
From the viewpoint of desulfurization performance, the supported amount of silver is preferably in the range of 5 to 30% by mass. An aqueous solution containing a silver source is prepared. Examples of the silver source include silver nitrate, silver acetate, and silver sulfate. These silver sources may be used alone or in combination. Examples of the alumina include γ-type, φ-type, χ-type, δ-type, and η-type alumina, and γ-type, χ-type, and η-type are preferably used. An aqueous solution containing the above silver source is impregnated and supported on alumina, dried at a temperature of about 80 to 150 ° C., and then baked at a temperature of about 200 to 400 ° C., thereby desulfurizing agent B having silver supported on an alumina carrier. Is obtained.

In addition, as conditions for the desulfurization treatment using the desulfurizing agent in the present invention, the temperature is usually selected in the range of −20 to 100 ° C., and the GHSV (gas space velocity) is 100 to 10,000 h ⁻¹ , preferably It is selected in the range of 100 to 2,000 h ⁻¹ , more preferably 100 to 1,000 h ⁻¹ .

Next, in the method for producing hydrogen used in the fuel cell system of the present invention, the desulfurized liquefied petroleum gas is converted into a partial oxidation reforming catalyst, an autothermal reforming catalyst, a steam reforming catalyst, or a carbon dioxide reforming catalyst. By contacting them, hydrogen is produced by partial oxidation reforming, autothermal reforming, steam reforming or carbon dioxide reforming, respectively.
In this reforming treatment, the concentration of the sulfur compound in the desulfurized liquefied petroleum gas is preferably 0.05 mass ppm or less, particularly preferably 0.02 mass ppm or less, from the viewpoint of the life of each reforming catalyst. .
The partial oxidation reforming is a method for producing hydrogen by a partial oxidation reaction of a hydrocarbon compound of liquefied petroleum gas, and in the presence of a partial oxidation reforming catalyst, the reaction pressure is usually normal pressure to 5 MPa · G. The reforming reaction is carried out under the conditions of a reaction temperature of 400 to 1,100 ° C., a GHSV of 1,000 to 100,000 h ⁻¹ , and an oxygen (O ₂ ) / carbon molar ratio of 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 · G, and the reaction temperature is from 400 to 1. , 100 ° C., oxygen (O ₂ ) / carbon molar ratio 0.1 to 1, steam / carbon molar ratio 0.1 to 10, and GHSV 1,000 to 100,000 h ⁻¹ .

Further, steam reforming is a method for producing hydrogen by bringing a hydrocarbon compound into contact with steam, and in the presence of a steam reforming catalyst, usually a reaction pressure of normal pressure to 3 MPa · G, a reaction temperature of 200 to 900. The reforming reaction is performed under the conditions of ° C., steam / carbon molar ratio of 1.5 to 10, and GHSV of 1,000 to 100,000 h ⁻¹ .
Carbon dioxide reforming is a method for producing hydrogen by causing a reaction between a hydrocarbon compound and carbon dioxide. The reaction conditions for hydrogen production are usually 200 to 1,300 ° C., preferably 400. It is -1200 degreeC, More preferably, it is 500-900 degreeC. The carbon dioxide / carbon molar ratio is usually 0.1 to 5, preferably 0.1 to 3. When steam is added, the steam / carbon molar ratio is usually 0.1 to 10, preferably 0.4 to 4. When oxygen is added, the oxygen / carbon molar ratio is usually 0.1 to 1, preferably 0.2 to 0.8. The reaction pressure is usually 0 to 10 MPa · G, preferably 0 to 5 MPa · G, more preferably 0 to 3 MPa · G. About GHSV, it is the same as that of the case of the said steam reforming.

  As the partial oxidation reforming catalyst, autothermal reforming catalyst, steam reforming catalyst and carbon dioxide reforming catalyst, any of the conventionally known catalysts can be appropriately selected and used. Nickel-based catalysts are 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 reaction system for the above reforming reaction may be either a continuous flow system or a batch system, but a continuous flow system is preferred.

The reaction format is not particularly limited, and any of a fixed bed type, a moving bed type and a fluidized bed type can be adopted, but a fixed bed type is preferred. There is no restriction | limiting in particular also as a form of a reactor, For example, a tubular reactor etc. can be used.
Hydrogen can be obtained by performing the steam reforming reaction, autothermal reforming reaction, partial oxidation reforming reaction, carbon dioxide reforming reaction of hydrocarbon compounds using the reforming catalyst under the above conditions. It is preferably used in a hydrogen production process of a fuel cell.

A fuel cell system using liquefied petroleum gas for a fuel cell according to the present invention is manufactured by a desulfurizer equipped with a desulfurizing agent, a reformer equipped with a reforming catalyst, a CO shift catalyst, and the like, and the reformer. And a fuel cell using hydrogen as a fuel. This fuel cell system will be described with reference to FIG.
The fuel in the liquefied petroleum gas cylinder 21 is introduced into the desulfurizer 23 via the fuel supply line 22 by a vaporization method. The desulfurizer 23 is filled with the desulfurizing agent A and / or the desulfurizing agent B, for example. The fuel desulfurized by the desulfurizer 23 is mixed with water from the water tank via the water pump 24 and then sent to the reformer 31 together with the air sent from the air blower 35. The reformer 31 is filled with a reforming catalyst, and hydrogen is produced from the fuel mixture (mixed gas containing hydrocarbon compound, water vapor and oxygen) sent to the reformer 31 by any of the reforming reactions described above. Is manufactured. Reference numeral 38 denotes a fuel gas flow rate adjusting valve.

  The hydrogen produced in this way is reduced to the extent that the CO concentration does not reach the characteristics of the fuel cell through the CO converter 32 and the CO selective oxidizer 33. Examples of catalysts used in these reactors include an iron-chromium-based catalyst, a copper-zinc-based catalyst, or a noble metal-based catalyst for the CO converter 32, and a ruthenium-based catalyst, platinum for the CO selective oxidizer 33. Examples thereof include a system catalyst or a mixed catalyst thereof. When the CO concentration in the hydrogen produced by the reforming reaction is low, the CO converter 32 and the CO selective oxidizer 33 may not be attached.

The fuel cell 34 is an example of a polymer electrolyte fuel cell including 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 if necessary (humidifier not shown). Is done.
At this time, a reaction in which hydrogen gas becomes protons and emits 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. In that case, platinum black or an activated carbon-supported Pt catalyst or Pt-Ru alloy catalyst is used for the negative electrode, and platinum black or an activated carbon-supported Pt catalyst 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, an air / water separator 36 is 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 water is used for generation of water vapor. can do. Since heat is generated in the fuel cell 34 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 is attached to the fuel cell 34 to deprive the heat generated during the reaction, a heat exchanger 37A, a heat exchanger 37B for exchanging the heat deprived by the heat exchanger 37A with water, 37C and a pump 37D that circulates the refrigerant to the heat exchangers 37A and 37B and the cooler 37C, and the hot water obtained in the heat exchanger 37B can be effectively used in other facilities.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Table 1 shows the properties of the liquefied petroleum gases 1 to 6 used.

(1) Preparation of Desulfurizing Agent A 200 g of a 500 ° C. burned product of β-type zeolite (“HSZ-930NHA” manufactured by Tosoh Corporation) and 35 g of silver nitrate (made by Wako Pure Chemical Industries, Ltd., special grade) were dissolved in 1000 ml of water. The solution was added to the aqueous solution and stirred for 4 hours for ion exchange. Thereafter, the solid was washed with water, collected by filtration, dried at 120 ° C. for 12 hours with a blower, and calcined at 400 ° C. for 3 hours to obtain a desulfurization agent A containing 6% by mass of Ag.

(2) Preparation of desulfurizing agent B Nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) 730.2 g and copper sulfate pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) 151.3 g was dissolved in 8 liters of water heated to 80 ° C., and 16.0 g of pseudo boehmite (catalyst chemical industry, “C-AP”, 67% by mass as Al ₂ O ₃ ) was added to 16.0 g. After mixing, 300 ml of 0.5 mol / liter sulfuric acid aqueous solution was added to adjust the pH to 2 (Preparation Solution A). Further, 600.0 g of sodium carbonate was dissolved in 8 liters of water heated to 80 ° C., and 180.2 g of water glass (manufactured by Nippon Chemical Industry Co., Ltd., “J-1”, Si concentration 29 mass%) was added. (Preparation solution B). The preparation liquid A and the preparation liquid B were mixed while being kept at 80 ° C. and stirred for 1 hour. Thereafter, the precipitated cake is washed with 60 liters of water, filtered, dried at 120 ° C. for 12 hours in a blow dryer, and further calcined at 350 ° C. for 3 hours, whereby Ni 50 mass% and Cu 13 mass%. A desulfurizing agent B containing was obtained.

Example 1 (LP-1, A)
3 ml of desulfurizing agent A was weighed and charged into a stainless steel reactor having a diameter of 0.8 cm. The liquefied petroleum gas 1 was evaporated by a natural vaporization method, and supplied at GHSV (gas space velocity) 7,500 h ⁻¹ (acceleration test with about 20 times GHSV compared with normal use) and 20 ° C. under normal pressure. An automatic sampling device was provided at the outlet of the desulfurizer, and each sulfur compound was analyzed by gas chromatography equipped with an SCD detector (Sulfur Chemiluminescence Detector) every 2 hours. The analysis was performed under the following conditions. Separation column: DB-1, length: 60 m, membrane pressure: 5 μm, ID: 0.32 mm, split ratio: 1: 5, carrier gas: helium, flow rate: 23 ml / min, temperature: held at 40 ° C. for 4 minutes The temperature was raised to 200 ° C. at 10 ° C./min and held at 200 ° C. for 15 minutes. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 80 hours.

Example 2 (LP-2, A)
The same experiment as in Example 1 was performed except that liquefied petroleum gas 2 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 104 hours.

Example 3 (LP-3, A)
An experiment similar to Example 1 was performed except that liquefied petroleum gas 3 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 140 hours.

Comparative Example 1 (LP-4, A)
An experiment similar to Example 1 was performed except that liquefied petroleum gas 4 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 18 hours.

Comparative Example 2 (LP-5, A)
An experiment similar to Example 1 was performed except that liquefied petroleum gas 5 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 46 hours.

Comparative Example 3 (LP-6, A)
An experiment similar to Example 1 was performed except that liquefied petroleum gas 6 was used as a raw material. As a result, the total sulfur concentration was maintained at 0.5 ppm or less until 50 hours.

Example 4 (LP-1, B)
An experiment similar to Example 1 was performed except that the desulfurizing agent B was used. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 76 hours.

Example 5 (LP-2, B)
An experiment similar to Example 2 was performed except that the desulfurizing agent B was used. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 98 hours.

Example 6 (LP-3, B)
An experiment similar to that of Example 3 was performed except that the desulfurizing agent B was used. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 142 hours.

Comparative Example 4 (LP-4, B)
An experiment similar to Example 4 was performed except that liquefied petroleum gas 4 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 24 hours.

Comparative Example 5 (LP-5, B)
An experiment similar to Example 4 was performed except that liquefied petroleum gas 5 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 48 hours.

Comparative Example 6 (LP-6, B)
The same experiment as in Example 4 was performed except that liquefied petroleum gas 6 was used as a raw material. As a result, the sulfur concentration was maintained at 0.5 ppm or less until 48 hours.

It is an example of the general | schematic flowchart of the fuel cell system of this invention.

Explanation of symbols

1: Fuel cell system 11: Water supply pipe 12: Fuel introduction pipe 20: Hydrogen production system 21: Liquefied petroleum gas cylinder 22: Fuel supply line 23: Desulfurizer 24: Water pump 31: Reformer 31A: Reformer burner 32: CO converter 33: CO selective oxidizer 34: Fuel cell 34A: Fuel cell negative electrode 34B: Fuel cell positive electrode 34C: Fuel cell polymer electrolyte 35: Air blower 36: Air / water separator 37: Waste heat recovery device 37A: Heat exchanger 37B: Heat exchanger 37C: Cooler 37D: Refrigerant circulation pump 38: Flow control valve

Claims (9)

  The content of hydrocarbon compounds having 2 carbon atoms is 3% by volume or less, the content of hydrocarbon compounds having 4 carbon atoms is 3% by volume or less, the total sulfur concentration is 10 mass ppm or less, and the sulfur concentration of methyl mercaptan is 3 masses. A liquefied petroleum gas for an LP gas fuel cell having a ppm or less and the balance comprising a hydrocarbon compound having 3 carbon atoms.   The liquefied petroleum gas for an LP gas fuel cell according to claim 1, wherein the methyl mercaptan has a sulfur concentration of 2 ppm by mass or less.   The liquefied petroleum gas for an LP gas fuel cell according to claim 2, wherein the total sulfur concentration is 7 mass ppm or less and the sulfur concentration of methyl mercaptan is 2 mass ppm or less.   The liquefied petroleum gas for an LP gas fuel cell according to claim 3, wherein the total sulfur concentration is 5 mass ppm or less, and the sulfur concentration of methyl mercaptan is 2 mass ppm or less.   A desulfurization method comprising desulfurization treatment using a desulfurizing agent after the liquefied petroleum gas for an LP gas fuel cell according to any one of claims 1 to 4 is naturally vaporized.   6. The desulfurization method according to claim 5, wherein the desulfurization agent is a desulfurization agent containing zeolite and / or a desulfurization agent composed of at least one selected from metal elements, metal oxides and metal component-supported oxides.   The desulfurizing agent containing zeolite is selected from the group consisting of Ag component, Cu component, Ni component, Zn component, Mn component, Fe component, Co component, alkali metal component, alkaline earth metal component and rare earth metal component together with zeolite. The desulfurization method according to claim 6, comprising at least one metal component.   The desulfurization method according to claim 6 or 7, wherein the zeolite has a beta (BEA) and / or faujasite (FAU) structure.   A desulfurization agent comprising at least one selected from metal elements, metal oxides and metal component-supported oxides is an Ag component, Cu component, Ni component, Zn component, Mn component, Fe component, Co component, Si component, Al The desulfurization method according to claim 6, comprising at least one metal component selected from the group consisting of a component, an alkali metal component, an alkaline earth metal component, and a rare earth metal component.

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