JP2006316154A - Liquefied petroleum gas for lp gas fuel cell, its desulfurization method and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquefied petroleum gas for LP gas fuel cells, a desulfurization method for the gas and a fuel cell system to use a hydrogen-containing gas produced by reforming a liquefied petroleum gas desulfurized by the desulfurization method. <P>SOLUTION: The liquefied petroleum gas for LP gas fuel cells has a 2C paraffin and olefin content of ≤3 vol.%, a 4C paraffin, olefin and diolefin content of ≤3 vol.%, a sulfur concentration of ≤10 mass ppm, and the residual amount of 3C paraffin and olefin. The total content of the above olefins and diolefins is ≤0.9 vol.%. The invention further provides a fuel cell system to use a hydrogen-containing gas produced by reforming a liquefied petroleum gas desulfurized by the desulfurization treatment of the liquefied petroleum gas with a desulfurization agent. <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, a desulfurization method thereof, and a fuel cell system using a hydrogen-containing gas obtained by reforming using a liquefied petroleum gas subjected to desulfurization treatment. .

  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 20% by volume or less, and the sulfur concentration is 150 ppm by mass or less.
As methods for supplying these liquefied petroleum gas to gas equipment, there are a natural vaporization method and an evaporation method using a heat source. In the evaporation method, the amount of liquefied petroleum gas used is sequentially evaporated to generate a supply gas, so that the composition of the hydrocarbon compound in the cylinder and the supply gas are almost the same.
On the other hand, the natural vaporization system has a characteristic that the sulfur concentration in the supplied gas increases as the amount of liquefied petroleum gas in the cylinder increases, so it is difficult to completely desulfurize. In addition, since hydrocarbon compounds with a low boiling point filled in the cylinder are more likely to evaporate, the hydrocarbon compounds supplied to the fuel cell system gradually become heavier with the use of liquefied petroleum gas in the cylinder. As a result, when such a fuel gas is used, the amount of hydrogen generated decreases, and an operation of increasing the amount of gas supplied to the fuel cell in order to obtain the required power has been required.
However, there is no means to accurately measure the supply amount following the change in the composition of the liquefied petroleum gas, the fuel supply amount for obtaining the desired power amount is estimated, and the supply according to this approximate value is performed. Furthermore, it was necessary to take a method of feeding back the amount of electric power obtained to the supply amount and gradually adjusting the supply amount.
Patent Document 2 contains a desulfurization agent layer containing zeolite and at least one selected from the group consisting of metal elements, metal oxides, and metal component-supported oxides as a method for removing sulfur compounds in gaseous hydrocarbon compounds. A method for removing sulfur compounds using a desulfurizer combined with a desulfurizing agent layer is disclosed. This combination of desulfurizing agent layers is effective to some extent as a desulfurization technique for hydrocarbon gas containing various sulfur compounds, but the difference in desulfurization performance due to the composition of hydrocarbon compounds in liquefied petroleum gas has not been clarified.

  Further, if a small amount of sulfur compound leaks downstream from the desulfurizer, the reforming catalyst in the reformer on the downstream side is damaged, and a predetermined amount of hydrogen continuously supplied to the fuel cell cannot be obtained. Therefore, when the reforming catalyst is damaged, it is necessary to remove and replace the reformer, and replacement of the expensive reformer is extremely disadvantageous industrially. Therefore, it is important to prevent the sulfur compound from leaking out from the desulfurizer, even if it is a trace amount. Further, in the production of hydrogen used in fuel cells, the desulfurizer needs to be installed in the fuel cell system, particularly in fuel cells systems for general households and small-scale businesses where downsizing is desired. Therefore, further downsizing of the desulfurizer is required.

Masaki Ikematsu, “Engine Technology”, Sankai-do Co., Ltd., January 2001, Vol. 3, No. 1, p. 35 International Publication No. 02/000813 Pamphlet International Publication No. 04/058927 Pamphlet

  The present invention has been made in view of such a situation, and even if it is supplied by a natural vaporization supply system as a fuel for an LP gas type fuel cell system, it is hardly affected by the composition change of the supply gas, and is minimized. Even when using a desulfurizing agent, the desulfurizing agent functions efficiently, improving the desulfurizing effect, preventing damage to the reforming catalyst in the reformer for hydrogen production arranged downstream from the desulfurizer, and improving the stability. Liquefied petroleum gas for LP gas fuel cells that enables operation of a gasifier and stable generation of electricity, desulfurization method thereof, and hydrogen obtained by reforming liquefied petroleum gas desulfurized by the desulfurization method An object of the present invention is to provide a fuel cell system using a contained gas.

As a result of intensive studies to achieve the above object, the present inventors have devised a liquefied petroleum gas having a specific composition in which the total content of olefins and diolefins in the fuel gas is not more than a specific value. Based on this finding, the present invention has been completed.
That is, the present invention
(1) The content of carbon 2 paraffins and olefins is 3% by volume or less, the content of carbon 4 paraffins, olefins and diolefins is 3% by volume or less, the sulfur concentration is 10 mass ppm or less, and the balance is carbon number Liquefied petroleum gas for an LP gas fuel cell, which is supplied by a natural vaporization supply system, wherein the total content of the olefin and diolefin is 0.9 vol% or less,
(2) The content of olefins having 2 carbon atoms is 0.1 vol% or less, the content of olefins having 3 carbon atoms is 0.3 vol% or less, and the content of olefins and diolefins having 4 carbon atoms is 0.5 vol% or less. Liquefied petroleum gas for LP gas fuel cells supplied by the natural vaporization supply method described in (1) above,
(3) The liquefied petroleum gas for LP gas fuel cells supplied by the natural vaporization supply method according to the above (1) or (2), wherein the content of the diolefin having 4 carbon atoms is 0.03% by volume or less,

(4) The liquefied petroleum gas for an LP gas fuel cell supplied by the natural vaporization supply method described in any one of (1) to (3) above is desulfurized using a desulfurizing agent. Desulfurization method,
(5) The desulfurization method according to the above (4), 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,
(6) The group in which the desulfurizing agent including zeolite is composed of zeolite, 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 The desulfurization method according to the above (5), which contains at least one metal component selected from
(7) The desulfurization method according to the above (5) or (6), wherein the zeolite has a beta (BEA) and / or faujasite (FAU) structure,
(8) A desulfurization agent composed of 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 The desulfurization method according to (5) 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,

(9) The liquefied petroleum gas desulfurized by the desulfurization method according to any one of (4) to (8) above is reformed, and the hydrogen-containing gas obtained thereby is used. LP gas type fuel cell system,
It is.

  According to the present invention, the desulfurization agent in the desulfurizer functions efficiently even with the use of a minimum desulfurization agent, and the desulfurization effect is improved, so that in the reformer for hydrogen production disposed downstream from the desulfurizer. Liquefied petroleum gas for LP gas type fuel cells that can prevent damage to the reforming catalyst and enables stable operation of the reformer and stable power generation, its desulfurization method, and desulfurized by the desulfurization method A fuel cell system using a hydrogen-containing gas obtained by reforming liquefied petroleum gas can be provided.

Hereinafter, the present invention will be described in more detail.
In the present invention, the liquefied petroleum gas used as a fuel has a carbon number 2 paraffin and olefin content of 3% by volume or less, a carbon number 4 paraffin, olefin and diolefin content of 3% by volume or less, and a sulfur concentration of 10 mass. This is a liquefied petroleum gas for an LP gas fuel cell having a ppm or less, the balance being paraffin and olefin having 3 carbon atoms, and a total content of the olefin and diolefin being 0.9% by volume or less.

When the content of paraffins and olefins having 3 carbon atoms is preferably 96% by volume or more and less than 96% by volume, when such liquefied petroleum gas is used as a hydrogen raw material for a fuel cell in a vaporization supply system, Variations in the composition of the hydrocarbon compound may increase, making it difficult to adjust the gas flow rate. 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 paraffins, olefins and diolefins with 4 carbon atoms exceeds 3% by volume, if such liquefied petroleum gas is used as a hydrogen raw material for fuel cells in the vaporization supply system, hydrocarbons with 4 carbon atoms will be used at the end of the cylinder. The composition of the compound may increase, and sufficient hydrogen may not be generated to obtain a predetermined power in the reformer.
Further, the total content of olefins and diolefins in the liquefied petroleum gas is required to be 0.9% by volume or less from the viewpoint of suppressing the deterioration of the desulfurization agent due to the accumulation of coke. Preferably, the content is 0.1% by volume or less, the content of olefins having 3 carbon atoms is 0.3% by volume or less, and the content of olefins and diolefins having 4 carbon atoms is 0.5% by volume or less. In particular, it is preferable that the content of the C4-diolefin having a remarkable coke accumulation is 0.03% by volume or less.
Liquefied petroleum gas containing olefins and diolefins exceeding these ranges has a large effect on desulfurization agent performance, resulting in an increase in the amount of desulfurization agent used and an excessive increase in the size of the desulfurizer. In addition to being restricted by the size of the battery system itself, it is economically disadvantageous.
The composition for each carbon number is measured by the analysis method described in JIS K 2240 “Liquefied petroleum gas 5.9 composition analysis method”.

The sulfur concentration in the liquefied petroleum gas of the present invention is 10 mass ppm or less, preferably 5 mass ppm or less, more preferably 3 mass ppm or less. If it exceeds 10 ppm by mass, the amount of desulfurizing agent to be used increases, and the size of the desulfurizer becomes excessively large, which is not only economically disadvantageous but also limited by the size of the fuel cell system itself.
The sulfur concentration is a concentration measured by JIS K 2240 “Liquefied petroleum gas 5.5 or 5.6 sulfur content test method”.

  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 with crude oil atmospheric distillation equipment and liquefied petroleum gas components obtained with naphtha catalytic reforming equipment and catalytic cracking equipment are separated by distillation, then sulfur components are removed and further distilled. By separating, liquefied petroleum gas at the primary base of desired purity can be obtained. 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 a sulfur component added as an odorant, such as mercaptans such as methyl mercaptan, carbonyl sulfide, etc. Sulfur compounds such as hydrogen sulfide, sulfides, disulfides, thiophenes, 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. In order to maximize the performance of the desulfurizing agent to be used, it is preferable to use liquefied petroleum gas having a sulfur content as low as possible. For this purpose, carbonyl sulfide that is difficult to desulfurize compared to other sulfur compounds is used. It is preferable to use a material having as little content as possible.
Moreover, the desulfurization agent to be used may be a single type or a combination of desulfurization agents having different adsorption characteristics for each sulfur compound. 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. As the zeolite, those having a beta (BEA) and / or faujasite (FAU) structure are particularly preferable. Preferred examples of the alkali metal component include potassium and sodium, preferred alkaline earth metal components include calcium and magnesium, and preferred rare earth metal components 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 desulfurizing 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, white clay, clay, or zinc oxide, and among these, the silica support An alumina carrier and a silica-alumina carrier are preferable.
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 a liquefied petroleum gas for an LP gas fuel cell according to the present invention includes a desulfurizer provided with a desulfurizing agent, a reformer provided with a reforming catalyst, a CO shift catalyst, and the like, and the reformer And a fuel cell using hydrogen produced 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 pressure control 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.

(1) Preparation of desulfurizing agent A 500 g of 500 ° C. calcined product of β-type zeolite (“HSZ-930NHA” manufactured by Tosoh Corporation) and 350 g of silver nitrate (made by Wako Pure Chemical Industries, Ltd., special grade) in 10 liters of water The solution was put into a dissolved 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 7300 g of nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) and 1513 g of copper sulfate pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) After being dissolved in 80 liters of water heated to 80 ° C., 160 g of pseudo boehmite (Catalyst Chemical Industries, Ltd., “C-AP”, 67% by mass as Al ₂ O ₃ ) was mixed. The pH was adjusted to 2 by adding 3 liters of 5 mol / liter sulfuric acid aqueous solution (preparation solution A). Further, 6000 g of sodium carbonate was dissolved in 80 liters of water heated to 80 ° C., and 1802 g of water glass (manufactured by Nippon Chemical Industry Co., Ltd., “J-1”, Si concentration: 29 mass%) was added (preparation). Liquid 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 600 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.
(3) Reforming catalyst A commercially available ruthenium-based reforming catalyst was used.
(4) The properties of the used liquefied petroleum gases 1 to 4 are shown in Table 1.

Examples 1 and 2 and Comparative Examples 1 and 2
Liquefied petroleum gases 1 to 4 having the properties shown in Table 1 below were vaporized by a natural vaporization method, reduced to 0.08 MPa by a regulator (pressure control valve), and supplied to a desulfurization test apparatus. After passing through a dehydrator filled with 300 ml of molecular sieve 3A in the desulfurization test apparatus, the water content was reduced to 3 ppm by mass or less, and then passed through a desulfurizer filled with 300 ml of desulfurizing agent A and 150 ml of desulfurizing agent B, The concentration was desulfurized to 0.05 ppm by mass or less. A standard gas (manufactured by Takachiho Chemical Co., Ltd.) was introduced into this desulfurized liquefied petroleum gas so that dimethyl sulfide and tertiary butyl mercaptan would each contain 2.5 mass ppm of sulfur, and a fuel gas was prepared and tested. It was used for. In addition, it confirmed that the composition of the hydrocarbon compound in the said regulator exit and the said desulfurizer exit corresponded. The raw material gas thus prepared is passed through a desulfurizer filled with 15 ml of the desulfurizing agent A or B, and the sulfur concentration at the desulfurizer outlet is periodically analyzed, and the sulfur concentration reaches 0.1 mass ppm. The time to break (breakthrough time) was measured. The pressure is normal pressure, the flow rate is 1.4 liters / minute, and the temperature is 20 ° C. The results are shown in Table 2.
Further, liquefied petroleum gas 1, 2, 4 having the same composition as in Table 1 below was supplied to a 1 kW class LP gas type polymer electrolyte fuel cell (PEFC) system. This system is equipped with a desulfurizer filled with 300 ml of desulfurizing agent A and 150 ml of desulfurizing agent B. The reformer is filled with 600 ml of a commercially available reforming catalyst, 1 liter of a commercially available shift catalyst, and 0.25 liter of a commercially available selective oxidation catalyst. The flow rate of liquefied petroleum gas 1, 2, and 4 was adjusted to 1.8 liters / min with a thermal mass flow controller (manufactured by Okura Riken), and liquefied petroleum gas 1, 2, and 4 were supplied to the fuel cell system. The operating conditions of the reformer are a reformer outlet temperature of 700 ° C. and a pressure of 0.03 MPa · G. The amount of water supplied was adjusted so that the steam / carbon molar ratio at the beginning of the supply of liquefied petroleum gas was 1/3. When the amount of liquefied petroleum gas used reached 0.5 mass% and 98 mass%, the current value was set to 33.3 A and the voltage was measured. As a result, 39.0 V and 38.5 V (Example 1), respectively. ), 39.0 V and 38.3 V (Example 2) and 38.5 V and 36.0 V (Comparative Example 2).

組成はＪＩＳ Ｋ ２２４０ ５．９の「組成分析法」に従い分析した。但し、同法の５．９．８に規定される数値の算出は、オレフィン、ジオレフィンについては小数点３桁まで算出し、小数点２桁にまとめた。

The composition was analyzed according to “Composition analysis method” of JIS K 2240 5.9. However, in the calculation of numerical values stipulated in 5.9.8 of the same method, olefins and diolefins were calculated up to 3 decimal places and summarized to 2 decimal places.

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: Pressure control valve

Claims (9)

  Paraffins with 2 carbon atoms and olefin content of 3% by volume or less, paraffins with 4 carbon atoms, olefin and diolefin content of 3% by volume or less, sulfur concentration of 10 mass ppm or less, and the remainder with 3 carbon atoms. A liquefied petroleum gas for an LP gas fuel cell, which is supplied by a natural vaporization supply system, wherein the total content of the olefin and diolefin is 0.9% by volume or less.   The content of carbon 2 olefins is 0.1% by volume or less, the content of carbon 3 olefins is 0.3% by volume or less, and the content of carbon 4 olefins and diolefins is 0.5% by volume or less. Item 2. A liquefied petroleum gas for an LP gas type fuel cell supplied by the natural vaporization supply method according to Item 1.   The liquefied petroleum gas for an LP gas fuel cell supplied by the natural vaporization supply system according to claim 1 or 2, wherein the content of the diolefin having 4 carbon atoms is 0.03% by volume or less.   A desulfurization method, wherein the liquefied petroleum gas for an LP gas fuel cell supplied by the natural vaporization supply system according to any one of claims 1 to 3 is desulfurized using a desulfurizing agent.   The desulfurization method according to claim 4, 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 5, comprising at least one metal component.   The desulfurization method according to claim 5 or 6, 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 5, 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. An LP gas fuel cell system characterized by using a hydrogen-containing gas obtained by reforming a liquefied petroleum gas desulfurized by the desulfurization method according to any one of claims 4 to 8. .

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