JP2001262164A - Fuel oil for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide fuel oil for a fuel cell suitable for transportation of automobile, etc., capable of efficiently producing hydrogen, not exerting a bad influence on a reforming catalyst and a fuel cell electrode, having a slight deterioration of a reforming catalyst, etc. SOLUTION: This fuel oil for a fuel cell contains >=20 vol.% naphthene component, especially comprises a desulfurized heavy naphtha containing >=20 vol.% naphthene component as a main component.

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 producing hydrogen used in a fuel cell, and more particularly, to a fuel oil for transportation of a fuel cell comprising a petroleum hydrocarbon such as a gasoline fraction.

[0002]

2. Description of the Related Art In general, hydrogen is used as fuel for fuel cells. Examples of such hydrogen include those using hydrogen gas as it is, those using hydrogen obtained by reforming or decomposing methanol or the like, and those using room temperature. There have been proposed, for example, those using hydrogen obtained from city gas containing methane as a main component and LPG containing propane as a main component, which is gaseous at normal pressure. However, if hydrogen gas is used as it is, it is difficult to handle it because it is a gas itself, and methanol has problems such as low energy density, high cost, and lack of infrastructure. Yes, plus city gas and LPG
However, there is a problem that its use is limited in a region, and it is difficult to handle. Especially, when it is used as a fuel for a fuel cell for transportation such as for an automobile, there is a large practical problem. That is, in recent years, a fuel cell vehicle using a fuel cell having high energy efficiency and a small environmental load as a power source has attracted attention, and development of a fuel cell used for the fuel cell vehicle has been demanded. On the other hand, gasoline or a petroleum hydrocarbon fraction constituting the same, which has been conventionally used as a fuel for an internal combustion engine of an automobile or the like, has advantages such as being usually liquid and having a high energy density. It is thought that it can be used effectively for batteries. In addition, the infrastructure for such gasoline fractions is well developed.

[0003]

However, the gasoline fraction is not easily reformed compared to methanol or the like due to catalyst coke deterioration or catalyst poisoning.
There is also a problem that the life of the reforming catalyst is relatively short. The present invention has been made to solve the above problems.
That is, the present invention provides a fuel cell that can efficiently produce hydrogen, has little deterioration of the reforming catalyst without adversely affecting the reforming catalyst and the fuel cell electrode, and is suitable for transportation of automobiles and the like. It is intended to provide a fuel oil for use.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have found that the above object of the present invention is achieved by using a gasoline fraction having a specific composition and properties as the fuel oil for the fuel cell. It has been found that it can be achieved. The present invention has been completed based on such findings. That is,
The present invention relates to a fuel oil for a fuel cell, characterized by containing a naphthene content of 20% by volume or more, and in particular, a fuel cell mainly containing desulfurized heavy naphtha containing a naphthene content of 20% by volume or more. It relates to fuel oil for use.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention relates to a fuel oil for a fuel cell, comprising a naphthene content of 20% by volume or more, and more particularly to a fuel cell for transportation comprising a desulfurized heavy naphtha containing a naphthene content of 20% by volume or more. Pertaining to fuel oil for industrial use. The desulfurized heavy naphtha used here (hereinafter referred to as DH
N) is a petroleum hydrocarbon fraction composed of C ₆ -C ₁₀ normal paraffins, isoparaffins, naphthenes and the like. Such DHN is usually obtained by fractionating crude oil as heavy naphtha using a normal-pressure distillation apparatus and desulfurizing it using a naphtha desulfurization apparatus, or fractionating crude oil using a normal-pressure distillation apparatus as full-range naphtha and using a naphtha desulfurization apparatus. It is obtained by fractionating heavy naphtha after desulfurization.

DHN used in the fuel oil of the present invention contains at least 20% by volume of a naphthene component. When the naphthene component is less than 20% by volume, the effect of the present invention, particularly, The effect of suppressing deterioration cannot be obtained. From this viewpoint, the naphthene content is preferably 30% by volume or more, and more preferably 40% by volume or more. DHN containing such a naphthene content of 20% by volume or more can be prepared by a conventionally known method, for example, by using a naphthenic base crude oil as a crude oil before atmospheric distillation, or by subjecting benzene in DHN to hydrogenation treatment or more heavy treatment. It can be obtained by a method such as hydrocracking of a solid fraction. Further, as a substrate which may be used in a fuel oil of the present invention, LPG, after hydrogenation of C ₅ -C ₇ fraction obtained by distillation of the fraction obtained was naphtha and pyrolysis, benzene, The remaining fraction obtained by extracting toluene and xylene is used. These have a naphthenic content of 45-6.
It contains 5% by volume.

The DHN used in the present invention contains normal paraffin and isoparaffin as paraffin components, and the weight ratio of isoparaffin / normal paraffin is 1 or more, further 1.5 or more, especially 2.5 or more. Is preferred. When the above ratio is within this range, the effects unique to the present invention, such as little deterioration of the reforming catalyst, are likely to be obtained. Such isoparaffin-rich DHN is DH
It can be obtained by isomerization of N or separation and removal of normal paraffin by a molecular sieve.

The fuel oil of the present invention preferably has a sulfur content of 1 ppm by weight or less, more preferably 0.5% by weight pp.
m, particularly preferably 0.1 ppm by weight or less. If the sulfur content is higher than the above range, sulfur poisoning of the catalyst may occur, and problems such as deterioration of the reforming catalyst and the partial oxidation catalyst may occur. In the present invention, in order to obtain a fuel oil having a low sulfur content as described above, deep-desulfurized heavy naphtha can be used as DHN. Here, the deep desulfurized heavy naphtha means that the sulfur content of the DHN is 0.
It refers to one that has been treated so as to have a concentration of 5 ppm or less, further 0.1 ppm or less. The deep desulfurization heavy naphtha, for example,
1.0-2.5M in the presence of a catalyst commonly used in naphtha desulfurization equipment such as Co.Mo/alumina, Ni.W / alumina
Under a pressure of Pa, a temperature of 250 to 350 ° C., a liquid hourly space velocity (L
HSV) 3-10 hr ^-1 , hydrogen / feed oil 50-150 m
It can be obtained by reacting a feed oil with hydrogen under the condition of ³ / kl.

[0009] The deep desulfurized heavy naphtha in the present invention is a DHN obtained by performing the desulfurization treatment once or more times.
Can further be obtained by performing adsorptive desulfurization using the following specific catalyst. That is, examples of the catalyst that can be used for the adsorptive desulfurization include activated carbon, activated carbon fiber, silica gel, hydrophobic silica, zeolite, metal-exchanged zeolite, alkali / alkaline earth metal oxide, hydroxide, and sulfite hydrate. Or a salt of a compound such as
b, Sn, Fe, Ni, Co, Mn, Cr, Cu, Zn
Such metals, oxides thereof, mixtures thereof, composite oxides or these are silica, alumina, silica-alumina,
Those supported on a carrier such as titania, zirconia, zinc oxide, terra alba, diatomaceous earth, and clay;
Examples thereof include those supporting an alkaline earth metal, a rare earth metal such as Ce, La, and Y. Also, Pt,
What carried noble metals, such as Pd, Rh, and Ru, on the above-mentioned carrier can also be used.

DHN used in the present invention preferably has a carbon atom / hydrogen atom ratio of less than 0.55. The smaller this value is, the more excellent the hydrogen generation efficiency is, and the less adversely affects the reforming catalyst and the fuel cell electrode. The aromatic content in DHN is preferably 10% by weight or less, more preferably 8% by weight or less. When the aromatic content exceeds the above amount, the efficiency of hydrogen generation may be poor. Further, the fuel oil for a fuel cell of the present invention has a vapor pressure
It is preferably 0.098 MPa or less. The vapor pressure is 0.
When the pressure exceeds 098 MPa, the tank strength needs to be increased, or the release of hydrocarbons into the atmosphere becomes a problem, which may be undesirable. Therefore, in the present invention, the vapor pressure is more preferably in the range of 0 to 0.098 MPa.

The DHN according to the present invention is suitable for producing hydrogen for fuel cells because it has characteristics such as high purity of hydrogen produced by the method and a small decrease in hydrogen partial pressure. In particular, it is suitable as a fuel cell for transporting automobiles and the like because it is liquid. In order to generate hydrogen from DHN, DHN is first desulfurized as required. As the desulfurization method, usually, a hydrodesulfurization method is used, and the method is Co-Mo /
Using a hydrodesulfurization catalyst such as alumina or Ni-Mo / alumina and a hydrogen sulfide adsorbent such as ZnO,
This is carried out under a pressure of MPa and a temperature of 200 to 400 ° C.
Next, the desulfurized DHN is subjected to steam reforming and / or partial oxidation as required. ADVANTAGE OF THE INVENTION According to this invention, the fuel oil which can produce hydrogen efficiently without carbon deposition on a steam reforming catalyst etc. can be obtained.

Although there is no particular limitation on the method of steam reforming,
Usually, the following method is used. First, the steam reforming catalyst used in this hydrogen production method is not particularly limited, but as the supported metal, Ni, zirconium or ruthenium (Ru), rhodium (Rh), platinum (Pt)
And those using a noble metal such as These supported metals may be used alone or in combination of two or more. Among the supported metals, Ru is particularly desirable, and has a large effect of suppressing carbon deposition during the steam reforming reaction. The supported amount of Ru is 0.05 to 20 based on the carrier.
% By weight, more preferably 0.05 to 15% by weight.
If the supported amount is less than 0.05% by weight, the activity of the steam reforming reaction may be extremely reduced, and if it exceeds 20% by weight, a remarkable increase in the activity is hardly obtained.

Further, as a specific example of the combination of the supported metals, a combination of supporting Ru and zirconium may be mentioned. Ru and zirconium may be supported simultaneously or separately. The content of zirconium is 0.5 to 20% by weight, based on the carrier, in terms of ZrO ₂ ,
0.5 to 15% by weight is preferred. In the case of this type of supported metal, a metal further added with cobalt and / or magnesium is mentioned as a preferable one. Here, the content of cobalt is expressed as an atomic ratio of cobalt / ruthenium of 0.1.
The content of magnesium is preferably from 0.1 to 30, more preferably from 0.1 to 30, and the content of magnesium is 0.1 in terms of magnesia (MgO).
The content is preferably 5 to 20% by weight, more preferably 0.5 to 15% by weight. On the other hand, as a carrier of the catalyst used for steam reforming, an inorganic oxide is used, and specific examples thereof include alumina, silica, zirconia, magnesia, and a mixture thereof. Of these, alumina and zirconia are particularly preferred.

One of the preferred embodiments of the steam reforming catalyst is a catalyst in which Ru is supported on zirconia. This zirconia may be simple zirconia (ZrO ₂ ) or stabilized zirconia containing a stabilizing component such as magnesia. As the stabilized zirconia, those containing magnesia, yttria, ceria, and the like are preferable. As another preferable embodiment of the steam reforming catalyst, R
Examples of the catalyst include, in addition to u and zirconium, or Ru and zirconium, a catalyst in which cobalt and / or magnesium are further supported on an alumina carrier. As alumina, α-alumina which is particularly excellent in heat resistance and mechanical strength is preferable. Next, in the production of hydrogen, steam reforming is performed in a state where the ratio S / C (molar ratio) between steam (S) and carbon (C) derived from DHN is 2 to 5, and further 2 to 4. The method is preferred. If steam reforming is performed in a high S / C (molar ratio) of 5 or more, excess steam needs to be produced, resulting in large heat loss and reduced hydrogen production efficiency. Further, if the S / C is less than 2, the amount of generated hydrogen may decrease.

Further, in the production of hydrogen, it is preferable to carry out steam reforming while maintaining the inlet temperature of the steam reforming catalyst layer at 630 ° C. or lower. Since the inlet temperature of the steam reforming catalyst layer tends to increase due to the addition of oxygen, it is necessary to control the temperature. If the inlet temperature exceeds 630 ° C,
This is because thermal decomposition of the raw material hydrocarbon 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
Although not particularly limited, the reaction is preferably performed at 650 to 800 ° C. If the outlet temperature of the catalyst layer is lower than 650 ° C., the amount of generated hydrogen is not sufficient, and in order to react at a temperature exceeding 800 ° C., the reactor may need to be made of a heat-resistant material in particular.
This is because it is not economically preferable.

In the production of hydrogen, the reaction pressure is from normal pressure to normal pressure.
The pressure is preferably 3 MPa, more preferably normal pressure to 1 MPa. The flow rate of DHN was 0.1 LHSV.
１００100 h ⁻¹ . In the production of hydrogen, DHN can efficiently produce hydrogen even when used in producing hydrogen by combining the steam reforming and partial oxidation. The partial oxidation reaction is preferably performed under a catalyst in which a noble metal such as ruthenium or nickel is supported on a heat-resistant oxide, at a reaction pressure of normal pressure to 5 MPa, a reaction temperature of 400 to 1,100.
° C, oxygen / carbon ratio 0.2-0.8, LHSV 0.1-1
00h ^-1 . When steam is added, S
Performed at a / C ratio of 0.4 to 4. In the production method of the hydrogen, since the CO obtained by the steam reforming adversely affect the hydrogen production, CO this as CO ₂ by reaction
Is preferably removed.

[0017]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Example 1 A hydrogen production experiment was carried out as follows using DHN (composition shown in Table 1) obtained by subjecting high naphthenic crude oil to distillation processing using a batch type still having 15 theoretical stages. A coking test was performed on the catalyst after the reaction. The results are shown in Table 1.

Hydrogen Production Experiment Two fixed bed flow reactors were connected, desulfurization was performed in the first stage under the following conditions, and steam reforming was performed in the second stage. (First stage) Desulfurization Catalyst: Co-Mo (first stage) / ZnO (second stage) Conditions: normal pressure, temperature 330 ° C., LHSV = 1.3 h ⁻¹ (second stage) Reforming catalyst: α-alumina powder with water 20% by weight was added, and the mixture was mixed and compression-molded with a kneader to obtain a cylindrical molded body having a diameter of 5 mm and a length of 5 mm. After drying at 200 ° C. for 3 hours, it was calcined at 1280 ° C. for 26 hours to obtain an alumina carrier. On the other hand, in an aqueous solution of zirconium oxychloride (ZrO (OH) Cl) (2.5 g in terms of ZrO ₂ ), 0.66 g of ruthenium trichloride (RuCl ₃ / nH ₂ O) (containing 38% of Ru), cobalt nitrate 2.47 g of (Co (NO ₃ ) · 36H ₂ O) and 6.36 g of magnesium nitrate (Mg (NO ₃ ) · 26H ₂ O) were added and stirred until dissolved. The total amount of the solution was 10 cc. This solution was impregnated with 50 g of the above alumina carrier (pore filling method), dried at 120 ° C. for 5 hours, calcined at 500 ° C. for 2 hours, and further adjusted to a particle size of 16 to 32 mesh. This catalyst has 0.5% by weight of Ru, 5% by weight of Zr in terms of zirconia, 1.0% by weight of Co, and 2% by weight of Mg in terms of magnesia on a carrier basis. Conditions: steam / carbon ratio 1.5, LHSV of feed oil = 2.5 h ^-1 , normal pressure, catalyst layer inlet temperature 500 ° C., catalyst layer outlet temperature 700 ° C. The eye catalyst was extracted and the carbon deposition rate on the catalyst was measured and calculated as follows. Carbon deposition rate (%) = length of carbon deposited portion / length of total catalyst

Comparative Example 1 Hydrogen production of DHN (composition shown in Table 1) obtained by distilling a low naphthenic crude oil with a batch type still having 15 theoretical stages in the same manner as in Example 1 Experiments and coking tests were performed. The results are shown in Table 1.

[0020]

[Table 1]

[0021]

As described in detail above, the present invention provides
By using a fuel oil containing a naphthene content of 20% by volume or more, particularly a fuel oil composed of desulfurized heavy naphtha having a naphthene content of 20% by volume or more, hydrogen used for a fuel cell can be efficiently produced, It is possible to provide a fuel oil for a fuel cell suitable for transportation of automobiles and the like, which causes little deterioration of the reforming catalyst without adversely affecting the reforming catalyst and the fuel cell electrode.

Claims (6)

[Claims] 1. A fuel oil for a fuel cell containing a naphthene content of 20% by volume or more. 2. A fuel cell fuel oil containing a naphthene content of 30% by volume or more. 3. A fuel oil for a fuel cell mainly comprising desulfurized heavy naphtha containing a naphthene content of 20% by volume or more. 4. The fuel oil for a fuel cell according to claim 3, which contains a naphthene component in an amount of 30% by volume or more. 5. The fuel oil for a fuel cell according to claim 1, which contains a sulfur content of 0.5 ppm by weight or less. 6. The fuel oil for a fuel cell according to claim 1, which contains a sulfur content of 0.1 ppm by weight or less.