JP2001294874A - Fuel oil for kerosene-based fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fuel oil for a kerosene-based fuel cell capable of efficiently removing contained sulfur to an ultralow concentration, reducing the load on a desulfurizing agent, and prolonging the life of a steam reforming catalyst in the stage of hydrogen production. SOLUTION: This fuel oil for the kerosene-based fuel cell satisfies conditions represented by the following formula (1): 0.256×[content of an alkyldibenzothiophene (wt.ppm) in the fuel oil]+1.103×[a polycyclic aromatic hydrocarbon compound (vol.%) in the fuel oil]-2.615<=2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel oil for a kerosene fuel cell, and more particularly to a fuel oil for a kerosene fuel cell capable of efficiently removing sulfur to an extremely low concentration. The present invention relates to a fuel oil for a kerosene-based fuel cell, which can reduce the load on the fuel cell and extend the life of the steam reforming catalyst.

[0002]

2. Description of the Related Art In recent years, new energy technologies have been spotlighted due to environmental problems, and fuel cells have attracted attention as one of the new energy technologies. This fuel cell converts chemical energy into electric energy by electrochemically reacting hydrogen and oxygen, and has the feature of high energy use efficiency.
Practical research is being actively conducted for industrial or automotive use. As the fuel cell, types such as a phosphoric acid type, a molten carbonate type, a solid oxide type, and a solid polymer type are known according to 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 natural gas, synthetic liquid fuel composed of natural gas as raw material, and petroleum LP
The use of petroleum hydrocarbons such as G, naphtha, and kerosene is being studied. When fuel cells are used for consumer or automotive applications, the above petroleum hydrocarbons, especially kerosene, are liquid at normal temperature and normal pressure, are easy to store and handle, and have a supply system such as gas stations and dealers. Is advantageous as a hydrogen source.

[0003] However, petroleum hydrocarbons have a problem that they have a higher sulfur content than methanol and natural gas fuels. When hydrogen is produced using this petroleum hydrocarbon, a method is generally used in which the hydrocarbon is subjected to steam reforming or partial oxidation reforming treatment in the presence of a reforming catalyst. In such a reforming treatment, since the reforming catalyst is poisoned by the sulfur content in the hydrocarbon, the hydrocarbon is desulfurized to reduce the sulfur content from the viewpoint of the catalyst life. It is important that the content be 0.2 ppm by weight or less. Many studies have been made on the desulfurization method of petroleum hydrocarbons, and various studies have been made mainly from the viewpoint of desulfurization catalysts. The review was not yet fully undertaken. In particular, at the time of desulfurizing petroleum hydrocarbons, no knowledge has been obtained as to a factor which indicates whether the petroleum hydrocarbons are easily or not easily desulfurized by a usual desulfurizing agent. Conventional petroleum hydrocarbons, particularly kerosene, are still insufficient to efficiently desulfurize the sulfur contained therein using a normal desulfurizing agent.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made under such circumstances, and is a fuel oil for a kerosene-based fuel cell which can efficiently remove a contained sulfur content to an extremely low concentration. It is another object of the present invention to provide a fuel oil for a kerosene-based fuel cell that can reduce the load on a desulfurizing agent and extend the life of a steam reforming catalyst in a hydrogen production stage.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that specific components in kerosene, particularly alkyldibenzothiophene, bicyclic aromatic hydrocarbon compounds, Polycyclic aromatic hydrocarbon compounds such as polycyclic aromatic hydrocarbon compounds with three or more rings are factors that control the degree of difficulty of desulfurization, and those whose content is within a specified range are the performance of desulfurizing agents. And can be used as a fuel oil for fuel cells, and the desulfurization treatment of fuel oil by steam reforming has the effect of extending the service life of the steam reforming catalyst. It has been found that hydrogen can be obtained efficiently. The present invention has been completed based on such findings. That is, the present invention provides a fuel oil for a kerosene-based fuel cell that satisfies the condition represented by the following formula (1). 0.256 × [content of alkyldibenzothiophene in fuel oil (weight ppm)] + 1.103 × [polycyclic aromatic hydrocarbon compound in fuel oil (volume%)] − 2.615 ≦ 2 (1)

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The fuel oil for a kerosene fuel cell of the present invention satisfies the condition represented by the above formula (1).
That is, 0.256 × [content of alkyldibenzothiophene in fuel oil (weight ppm)] + 1.103 × [polycyclic aromatic hydrocarbon compound in fuel oil (volume%)] − 2.61
The value F calculated in 5 is 2 or less. When the value of F is more than 2, the above-mentioned object of the present invention cannot be achieved, for example, desulfurization to a low sulfur concentration is difficult and application to fuel oil for fuel cells is difficult. From this point, the above value is preferably 1.5 or less, more preferably 1 or less.

In the present invention, any fuel oil that satisfies the condition represented by the above formula (1) can achieve the above object of the present invention. In particular, the alkyldibenzothiophene in the fuel oil is used. Is preferably 15 wt ppm or less, more preferably 10 wt ppm or less, in order to achieve the object of the present invention. If this value exceeds the above range, desulfurization to a low sulfur concentration may not be easy and application to fuel oil for fuel cells may be difficult. The alkyldibenzothiophenes targeted in the present invention include those whose alkyl group is a methyl group, an ethyl group, a propyl group, or a butyl group.

In the present invention, the content of the bicyclic aromatic hydrocarbon compound in the polycyclic aromatic hydrocarbon compound is preferably 2.0% by volume or less. When the content of the bicyclic aromatic hydrocarbon compound exceeds 2.0% by volume, desulfurization to a low sulfur concentration is not easy, and application to a fuel oil for a fuel cell is difficult. From such a point, the content of the bicyclic aromatic hydrocarbon compound is preferably 1.5% by volume or less, more preferably
1.0% by volume or less. Further, the fuel oil for a fuel cell of the present invention preferably contains not more than 0.2% by volume of a polycyclic aromatic hydrocarbon compound having three or more rings. When the content of the polycyclic aromatic hydrocarbon compound having three or more rings exceeds 0.2% by volume,
In some cases, desulfurization to a low sulfur concentration is not easy, and application to fuel oil for fuel cells may be difficult. From such a point, it is more preferable that the fuel oil for a fuel cell of the present invention does not substantially contain a polycyclic aromatic hydrocarbon compound having three or more rings.
In the present invention, examples of the tricyclic or higher polycyclic aromatic hydrocarbon compound include anthracene and phenanthrene. Further, the fuel oil of the present invention also contains a monocyclic aromatic hydrocarbon compound such as diethylbenzene and tetralin. The content of these compounds in the fuel oil is not particularly limited, but is preferably 20 to reduce coking in the reforming reaction.
It is preferable that it is not more than the volume%.

In order to prepare a fuel oil satisfying the formula (1) of the present invention, for example, a raw oil is generally subjected to a hydrorefining method which is industrially practiced (for example, nuclear hydrogenation, hydrocracking, etc.). Method. In this case, as a catalyst, usually, a mixture of transition metals such as nickel, cobalt, molybdenum, and tungsten in an appropriate ratio was supported on a carrier containing alumina as a main component in the form of a metal, oxide, or sulfide. Things are used. The reaction conditions are, for example, a reaction temperature of 250 to 400 ° C., a pressure of 2 to 10 MPa · G, a hydrogen / oil molar ratio of 2 to 10, a liquid hourly space velocity (LHSV) of 1 to 5
Conditions such as h ^-1 are used. The fuel oil for a kerosene-based fuel cell of the present invention is preferably applied to JIS No. 1 kerosene having a sulfur content of 80 ppm by weight or less. This JIS
No. 1 kerosene is obtained by desulfurizing crude kerosene obtained by distilling crude oil under normal pressure. The crude kerosene usually has a high sulfur content,
As it is, it does not become JIS No. 1 kerosene, and it is necessary to reduce the sulfur content. As a method of reducing the sulfur content, desulfurization treatment is preferably performed by a hydrorefining method that is generally carried out industrially. In this case, as a desulfurization catalyst, a mixture of transition metals such as nickel, cobalt, molybdenum, and tungsten in an appropriate ratio is usually supported on a carrier containing alumina as a main component in the form of a metal, oxide, or sulfide. Things are used. The reaction conditions are, for example, a reaction temperature of 250 to 400 ° C., a pressure of 2 to 10 MPa · G, a hydrogen / oil molar ratio of 2 to 10, a liquid hourly space velocity (LHSV) of 1 to 5
Conditions such as h ^-1 are used.

The properties of the fuel oil for a fuel cell of the present invention, such as boiling point fraction, flash point, smoke point, etc., are specified in the range of kerosene specified by Japanese Industrial Standards (JIS), especially JIS No. 1 kerosene. Those in the range are preferably used. As the desulfurizing agent used for desulfurizing the fuel oil for a kerosene-based fuel cell of the present invention, any desulfurizing agent usually used for desulfurizing a fuel oil for a fuel cell can be used. As a carrier for such a desulfurizing agent, for example, a porous carrier is preferable, and a porous inorganic oxide is particularly preferable. Such materials include, for example, silica, alumina, silica-alumina, titania, zirconia, magnesia, zinc oxide,
Examples include clay, clay, and diatomaceous earth. These may be used alone or in combination of two or more. Among these, silica-alumina is particularly preferred. As a metal component supported on these carriers, nickel is particularly suitable. If necessary, other metals such as copper, cobalt, iron, manganese, and chromium may be mixed. The supported amount of the nickel component is preferably 30% by weight or more based on the total amount of the desulfurizing agent.
If the amount is less than 30% by weight, sufficient desulfurization performance may not be exhibited. On the other hand, if the supported amount is too large, the ratio of the carrier is reduced, which causes a decrease in the mechanical strength and desulfurization performance of the desulfurizing agent. In consideration of desulfurization performance and mechanical strength, the more preferable amount of the nickel component is in the range of 40 to 80% by weight, and the more preferable amount of the nickel component is in the range of 50 to 70% by weight.

As a method for desulfurizing kerosene, which is a fuel oil for a fuel cell of the present invention, for example, the following method can be used. First, in a desulfurization tower filled with a desulfurizing agent,
Hydrogen is supplied in advance, and the desulfurizing agent is reduced at a temperature of about 150 to 400 ° C. Next, the fuel oil for a fuel cell of the present invention, for example, kerosene No. 1 is passed through the desulfurization tower in the liquid phase in an upward or downward flow, and the temperature is from normal temperature to about 400 ° C., the normal pressure is about 1 MPa · G, LHSV 0.02 to 1
The desulfurization treatment is performed under the condition of about 0 h ^-1 . At this time, if necessary, a small amount of hydrogen may be allowed to coexist. By appropriately selecting the desulfurization conditions within the above range, kerosene having a significantly reduced sulfur content can be obtained. The desulfurized fuel oil for a fuel cell is brought into contact with a steam reforming catalyst to produce hydrogen for a fuel cell.

The steam reforming catalyst used in the present invention is not particularly limited, and any one can be appropriately selected and used from known catalysts conventionally known as hydrocarbon steam reforming catalysts. . As such a steam reforming catalyst, for example, a catalyst in which a noble metal such as nickel, zirconium, ruthenium, rhodium, and platinum is supported on a suitable carrier can be exemplified. One of the above-mentioned supported metals may be supported, or two or more may be supported in combination. Among these catalysts, those supporting ruthenium (hereinafter referred to as ruthenium-based catalyst) are preferable, and have a large effect of suppressing carbon deposition during the steam reforming reaction. In the case of this ruthenium-based catalyst, the amount of supported ruthenium is preferably in the range of 0.05 to 20% by weight based on the carrier. If the supported amount is less than 0.05% by weight, the steam reforming activity may not be sufficiently exhibited.
If the amount exceeds the above, the effect of improving the catalytic activity is not so much recognized in spite of the supported amount, which is rather economically disadvantageous. Taking into account the catalytic activity and economic efficiency, the more preferable amount of the supported ruthenium is 0.05 to 15% by weight, particularly 0.1 to 0.1% by weight.
A range of 1 to 2% by weight is preferred.

When ruthenium is supported, it can be supported in combination with another metal, if desired. Examples of the other metal include zirconium, cobalt, and magnesium. When carrying a combination of ruthenium and zirconium, the supported amount of zirconium in the carrier reference as ZrO _2, usually 0.5 to 20 wt%, preferably from 0.5 to 15 wt%, more preferably 1
-15% by weight. When ruthenium and cobalt are supported in combination, the supported amount of cobalt is such that the atomic ratio of cobalt to ruthenium is usually 0.01 to 30, preferably 0.1 to 30, and more preferably 0.1 to 10. Is chosen to be Furthermore, when carrying ruthenium and magnesium in combination,
The loading amount of magnesium is usually 0.5 to 20% by weight, preferably 0.5 to 15% by weight based on the carrier as MgO,
More preferably, it is selected in the range of 1 to 15% by weight. On the other hand, as the carrier, an inorganic oxide is preferred, and specific examples thereof include alumina, silica, zirconia, magnesia, and a mixture thereof. Of these, alumina and zirconia are particularly preferred.

One preferred embodiment of the steam reforming catalyst is a catalyst in which ruthenium is supported on zirconia. This zirconia is a simple zirconia (ZrO ₂ )
Alternatively, stabilized zirconia containing a stabilizing component such as magnesia may be used. As the stabilized zirconia, those containing magnesia, yttria, ceria, and the like are preferable. Another preferred embodiment of the steam reforming catalyst is a catalyst in which, in addition to ruthenium and zirconium, or ruthenium and zirconium, cobalt and / or magnesium are further supported on an alumina carrier. As the alumina, α-alumina which is particularly excellent in heat resistance and mechanical strength is preferable. As the reaction conditions in the steam reforming treatment, the ratio S / C (molar ratio) between steam and carbon derived from fuel oil such as kerosene is usually 2 to 5, preferably 2 to 4, more preferably 2 to 3. Is selected in the range. If the S / C molar ratio is less than 2, the amount of generated hydrogen may decrease. If the S / C molar ratio exceeds 5, an excessive amount of steam is required, heat loss is large, and the efficiency of hydrogen production is unpreferably reduced.

Further, the inlet temperature of the steam reforming catalyst layer is set to 63
It is preferable to carry out steam reforming at a temperature of 0 ° C. or lower, more preferably 600 ° C. or lower. If the inlet temperature exceeds 630 ° C., the thermal decomposition of kerosene is promoted, and carbon is deposited on the catalyst or the reaction tube wall via generated radicals, which may make operation difficult. The catalyst layer outlet temperature is not particularly limited.
A range from 50 to 800C is preferred. The catalyst layer outlet temperature is 6
If the temperature is lower than 50 ° C., the amount of generated hydrogen may not be sufficient. If the temperature exceeds 800 ° C., the reactor may require a heat-resistant material, which is not economically preferable. The reaction pressure is usually in the range of normal pressure to 3 MPa, preferably normal pressure to 1 MPa, and the LHSV is usually in the range of 0.1 to 100 h ^-1 , preferably 0.2 to 50 h ^-1 . In the method for producing hydrogen, the CO obtained by the steam reforming is used.
Has an adverse effect on hydrogen production,
It is preferable to remove CO as O ₂ . In this way, hydrogen for a fuel cell can be efficiently produced.

[0016]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Preparation Example 1 Preparation of nickel-based desulfurizing agent 50.9 g of nickel chloride was dissolved in 500 ml of water, and 0.6 g of a carrier (alumina) was added thereto.
A solution (A) was prepared by adding 20 ml of an aqueous nitric acid solution having a concentration of mol / liter to adjust the pH to 1. On the other hand, water 5
After dissolving 33.1 g of sodium carbonate in 00 ml, 11.7 g of water glass (SiO ₂ concentration: 29% by weight) was added to prepare solution (B). Next, after the above solution (A) and solution (B) were heated to 80 ° C., respectively, they were instantaneously mixed, and the mixture was kept at 80 ° C. for 1 hour.
Stirred for hours. Thereafter, the product was thoroughly washed with 60 liters of distilled water, filtered, and then the solid was removed.
Dry for 12 hours in a blast dryer at 20 ° C, then 300 ° C
For 1 hour to obtain a desulfurizing agent in which 63% by weight of nickel was supported on a silica-alumina carrier.

[0017] The desulfurization performance of the fuel oil for a fuel cell was evaluated according to the following method. <Desulfurization Performance> 15 ml of the desulfurizing agent prepared in Preparation Example 1 is charged into a stainless steel reaction tube having an inner diameter of 17 mm. Next, the temperature was raised to 120 ° C. in a hydrogen stream under normal pressure, and the temperature was maintained for 1 hour.
By holding for a time, the desulfurizing agent is activated. next,
The temperature of the reaction tube was maintained at 150 ° C., and JIS No. 1 kerosene having a sulfur concentration shown in Table 1 was added under normal pressure to LHSV10.
At h- ¹ , supply to the reaction tube is started. After 5 hours, the sulfur concentration in the treated kerosene was analyzed according to JIS K2541 (microcoulometric titration method) to evaluate the desulfurization performance.
The content of alkyldibenzothiophene in kerosene is
The GC-AED method (gas chromatograph with an atomic emission detector) was used, and the content of the polycyclic aromatic hydrocarbon compound was measured using ASTM D2425 mass spectrometry.
In the GC-AED method, pure dibenzothiophene was first mixed with kerosene to determine the retention time of dibenzothiophene, and all peaks detected after this time were regarded as alkyldibenzothiophenes. The concentration of alkyldibenzothiophene was determined by the following equation. Alkyl dibenzothiophene concentration (ppm by weight) = total sulfur concentration in kerosene x (area value of alkyl dibenzothiophene determined by GC-AED / total sulfur compound area value determined by GC-AED)

Examples 1 to 3 and Comparative Example 1 JIS No. 1 kerosene having the composition and properties shown in Table 1 was used, and each was subjected to a desulfurization test. The results are shown in Table 1. Example 4 15 ml of the same desulfurizing agent used in the evaluation of desulfurization performance was charged into a stainless steel reaction tube having an inner diameter of 17 mm. Next, the temperature was raised to 120 ° C. in a hydrogen stream under normal pressure, and the temperature was maintained for 1 hour.
By holding for a time, the desulfurizing agent was activated. next,
The temperature of the reaction tube was maintained at 150 ° C., and the kerosene used in Example 1 was passed through the reaction tube at LHSV 2 h ⁻¹ under normal pressure. Further, a ruthenium-based reforming catalyst (ruthenium loading 0.5 wt. %) Steam reforming treatment was performed by a reformer filled with 30 ml. The reforming conditions were as follows: pressure: atmospheric pressure, steam / carbon (S / C) molar ratio 2.5, LHS
V: 1.0 h ^-1 , inlet temperature: 500 ° C., outlet temperature: 75
0 ° C. As a result, the conversion at the outlet of the reformer after the elapse of 200 hours was 100%. The sulfur content of the desulfurized kerosene during this reaction period was 0.2 ppm by weight or less. The conversion rate is expressed by the formula: conversion rate (%) = 100 × B / A (where A is the total amount of carbon in the supplied kerosene (molar flow rate) and B is the reformer outlet gas per hour. This is the total carbon amount (molar flow rate) of the C1 compound in the formula (1). The analysis is based on a gas chromatography method.

Comparative Example 2 In Example 4, a desulfurization treatment and a steam reforming treatment of kerosene were performed in the same manner as in Example 3, except that the kerosene used in Comparative Example 1 was used. As a result, the conversion at the outlet of the reformer was less than 100% after 30 hours, and oil droplets were confirmed at the outlet of the reformer after 47 hours. In addition, 75 hours and 10
After 5 hours, the sulfur content in the desulfurized kerosene was 4.6 ppm by weight and 11 ppm by weight, respectively.

[0020]

[Table 1]

[0021]

According to the fuel oil for a kerosene-based fuel cell of the present invention, by satisfying the condition represented by the formula (1), the contained sulfur can be efficiently removed to an extremely low concentration, and The load on the desulfurizing agent can be reduced, and the life of the steam reforming catalyst in the hydrogen production stage can be prolonged.

Continuation of front page (72) Inventor Kazuhito Saito 1280 Kamiizumi, Sodegaura-shi, Chiba F-term (reference) 5H027 AA02 BA01 BA16

Claims (5)

[Claims] 1. A fuel oil for a kerosene-based fuel cell that satisfies the condition represented by the following formula (1). 0.256 × [content of alkyldibenzothiophene in fuel oil (weight ppm)] + 1.103 × [polycyclic aromatic hydrocarbon compound in fuel oil (volume%)] − 2.615 ≦ 2 (1) 2. The fuel oil according to claim 1, wherein the content of the alkyldibenzothiophene in the fuel oil is 15 ppm by weight or less. 3. The fuel oil according to claim 1, wherein the content of the alkyldibenzothiophene in the fuel oil is 10 ppm by weight or less. 4. The fuel oil according to claim 1, wherein the content of the bicyclic aromatic hydrocarbon compound in the fuel oil is 2.0% by volume or less. 5. The fuel oil according to claim 1, wherein the content of the polycyclic aromatic hydrocarbon compound having three or more rings is not more than 0.2% by volume.
The fuel oil according to any one of the above.