JP2001262161A - Fuel oil for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a 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 less deterioration of a reforming catalyst, etc. SOLUTION: This fuel oil for a fuel cell is characterized by comprising a deep-desulfurized light naphtha.

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 transporting a fuel cell comprising a 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 in that its use is limited in a region, and it is difficult to handle. Especially, when it is used for a fuel cell for transportation such as an automobile, there is a serious problem in practice. 2. Description of the Related Art In recent years, fuel cell vehicles powered by fuel cells having high energy efficiency and low environmental load have attracted attention, and the development of fuel cells used for these vehicles has been demanded. On the other hand,
Gasoline or a hydrocarbon fraction constituting it, which has been conventionally used as a fuel for internal combustion engines of automobiles and the like, is usually liquid and has advantages such as high energy density, and is effectively used for fuel cells. It is considered possible.
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.
In other words, the present invention is directed to a fuel cell suitable for transportation of automobiles and the like, which can efficiently produce hydrogen and has little deterioration of the reforming catalyst without adversely affecting the reforming catalyst and the fuel cell electrode. It aims to provide fuel oil.

[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 provides a method for producing hydrogen from (1) a fuel oil for fuel cells containing deep desulfurized light naphtha, and (2) hydrogen from the fuel oil for fuel cells described in (1) above without performing desulfurization treatment. And (3) a reformer for hydrogen production without using a desulfurizer, which uses the fuel oil for a fuel cell according to the above (1).

[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, which contains lightly-desulfurized light naphtha. Here, the "desulfurized light naphtha" is either normal paraffins C ₄ -C _7, isoparaffins, is composed of naphthene, usually fractionated as light naphtha crude oil in atmospheric distillation unit, desulfurization in naphtha desulfurization apparatus Alternatively, the crude oil is obtained by fractionating crude oil as full-range naphtha with a normal-pressure distillation apparatus, desulfurizing the crude oil with a naphtha desulfurization apparatus, and then fractionating light naphtha.

In the present invention, "depth-desulfurized light naphtha" refers to the above desulfurized light naphtha having a sulfur content of 0.5 ppm by weight or less, preferably 0.1 ppm by weight or less, more preferably 0.05 ppm by weight. In the following, it refers to a naphtha that has been further treated so as to have a concentration of preferably 0.02 ppm by weight or less, or a desulfurized naphtha which is desulfurized under more severe conditions than a normal desulfurization treatment. If the sulfur content is larger than the above value, the reforming catalyst is poisoned with sulfur, which causes problems such as deterioration of the reforming catalyst and the partial oxidation catalyst, which is not preferable. The deep desulfurized light naphtha is, for example, Co.Mo/alumina, Ni.
W / Alumina, etc., in the presence of a catalyst commonly used in naphtha desulfurization equipment, under a pressure of 1.0 to 2.5 MPa, at a temperature of 250 to 3
It can be obtained by reacting a raw oil with hydrogen under the conditions of 50 ° C., a liquid hourly space velocity (LHSV) of 3 to 10 hr ⁻¹ , and hydrogen / raw oil of 50 to 150 m ³ / kl.

[0007] The deep desulfurized light naphtha in the present invention can be prepared, for example, by repeating the desulfurized light naphtha obtained by the above method again or a plurality of times within the range of the above desulfurization method. Further, the deep desulfurized light naphtha of the present invention can be obtained by further subjecting the desulfurized light naphtha obtained by the above one or more desulfurization treatments to adsorption 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,
Compound salts such as alkali / alkaline earth metal oxides, hydroxides and sulfite hydrates, or Pb, Sn, F
e, metals such as Ni, Co, Mn, Cr, Cu, Zn, oxides thereof, mixtures thereof, composite oxides or these are silica, alumina, silica-alumina, titania, zirconia, zinc oxide, clay, diatomaceous earth; Examples thereof include those supported on a carrier such as clay, and those further supported thereon, such as alkali / alkaline earth metals and rare earth metals such as Ce, La, and Y. Also, Pt, Pd, Rh,
What carried noble metal, such as Ru, on the said support can also be used.

Here, the above Pb, Sn, Fe, Ni, C
As a metal such as o and Cu or a noble metal such as Pt, Pd, Rh, and Ru, it is preferable to use a metal that has been subjected to a reduction treatment in advance. Examples of the catalyst that can be used for the above-mentioned adsorptive desulfurization include Pb, Sn, Fe, Ni, Co, Mn,
Preferably, Cr, Cu, Zn are used alone or in combination on a carrier. Further, those obtained by adding a rare earth metal such as an alkali / alkaline earth metal and Ce, La, Y to these can also be preferably used.
As these metals, those which have been previously subjected to a reduction treatment are preferably used, and those which have been treated and stabilized with carbon dioxide gas or the like can also be used. In the present invention, deep desulfurized light naphtha is obtained by subjecting desulfurized light naphtha which does not reach deep desulfurized light naphtha (for example, having a sulfur content exceeding 0.5 ppm by weight) to adsorption desulfurization with the above various catalysts. This is also one preferred embodiment.

[0009] The fuel oil for a fuel cell of the present invention contains the above-mentioned deep desulfurized light naphtha, but preferably contains at least 10% by volume, more preferably at least 50% by volume.
It is preferred to contain. If the content of deep desulfurized light naphtha is less than the above range, the reforming catalyst may be deteriorated, which is not preferable. As the fuel oil of the present invention, it is possible to use a fuel oil which contains depth-desulfurized light naphtha having various sulfur contents as appropriate according to the purpose at the above-mentioned content and, if necessary, is mixed with another base material. In the fuel oil for a fuel cell according to the present invention, a base material that can be mixed with the above-mentioned deep desulfurized light naphtha can be used in combination. As such a mixable base material, alkylate (ALK) is used. , Methyl tertiary butyl ether (M
TBE), isopentane, desulfurized light naphtha (excluding the deep desulfurized light naphtha of the present invention), and desulfurized heavy naphtha.

The fuel oil for a fuel cell of the present invention obtained as described above has a sulfur content of 1 wt ppm or less for the same reason as the sulfur content of the deep desulfurized light naphtha.
Further, it is preferably 0.5 ppm by weight or less, particularly preferably 0.1% by weight or less, particularly preferably 0.05% by weight or less. The fuel oil for a fuel cell of the present invention preferably has an aromatic content of 1% by weight or less. If 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 of 0.098MPa.
It is preferable that it is not more than a. Vapor pressure is 0.098MPa
When the pressure exceeds, 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 0 to 0.0.
More preferably, it is in the range of 98 MPa.

The fuel oil for a fuel cell of the present invention has characteristics such as high purity of hydrogen produced by the method and a small decrease in hydrogen partial pressure, and is suitable for producing hydrogen for a fuel cell. 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 fuel oil for a fuel cell, the fuel oil is usually first desulfurized as required. As the desulfurization method, usually, hydrodesulfurization method is used,
The method is Co-Mo / alumina or Ni-Mo /
Using a hydrodesulfurization catalyst such as alumina and a hydrogen sulfide adsorbent such as ZnO, at a pressure of normal pressure to 5 MPa and a temperature of 200 to
This is performed at 400 ° C. In the present invention, since the above-mentioned deep desulfurized light naphtha is used, it is also possible to omit the above desulfurization step depending on the amount of such deep desulfurized light naphtha used.

Next, the fuel oil desulfurized as required is subjected to steam reforming and / or partial oxidation. 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. The method of steam reforming is not particularly limited, but is usually performed by the following method. The steam reforming catalyst used in this hydrogen production method is not particularly limited, but the following is preferably used. First, Ni, zirconium or ruthenium (Ru), rhodium (Rh), platinum (P
Noble metals such as t). These may be used alone or in combination of two or more. Among these, a catalyst supporting Ru is particularly desirable, and has a large effect of suppressing carbon deposition during the steam reforming reaction. The supported amount of Ru is preferably 0.05 to 20% by weight, more preferably 0.05 to 15% by weight based on the carrier. If the supported amount is less than 0.05% by weight, the activity of the steam reforming reaction may extremely decrease, which is not preferable. 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 a preferred embodiment of the steam reforming catalyst, a catalyst in which Ru and zirconium, or in addition to Ru and zirconium, cobalt and / or magnesium is further supported on an alumina carrier can be mentioned. As alumina, α-alumina which is particularly excellent in heat resistance and mechanical strength is preferable. Next, in the production of hydrogen, the ratio S / C (molar ratio) between steam (S) and carbon (C) derived from fuel oil is 2 to 2.
5, and more preferably a method of performing steam reforming in the state of 2-4. If steam reforming is performed in a high S / C (molar ratio) of 5 or more, excess steam must be produced, resulting in a large heat loss and reduced hydrogen production efficiency. Also, S / C is 2
If it is less than, the amount of generated hydrogen is undesirably reduced.

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. Also, the flow rate of the fuel oil is 0.1 LHSV.
１００100 h ⁻¹ . In the production of hydrogen, even when the fuel oil is used in producing hydrogen by combining the steam reforming and partial oxidation, hydrogen can be produced efficiently. 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.

In the above-described method for producing hydrogen, the fuel oil for a fuel cell of the present invention containing deep desulfurized light naphtha is used as the fuel oil. At this time, as described above, it is possible to omit the desulfurization treatment in the desulfurization step depending on the content of the deep desulfurized light naphtha. Therefore, as a reformer for hydrogen production used for producing hydrogen as described above, a reformer without a desulfurizer may be used in some cases. That is, a reformer for hydrogen production is generally a desulfurizer that performs the above-described desulfurization step on fuel oil, and then performs a steam reforming and / or partial oxidation step on the desulfurized fuel oil to obtain hydrogen. And a reformer for performing the step of removing the CO from the reformed gas. In the present invention, it is possible to provide a reformer for hydrogen production that can introduce fuel oil directly into a reformer without providing the above desulfurizer by using deep desulfurized light naphtha as fuel oil. it can.

[0018]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Examples 1-4 and Comparative Examples 1-2 Deep desulfurized light naphtha A-C and desulfurized light naphtha D (collectively referred to as "DLN") were prepared by the following method, and Table 1 was prepared using these. A fuel oil having the composition described in Example 1 was prepared. Using these fuel oils, a hydrogen production experiment was performed as shown below, and a coking test was performed on the catalyst after the reaction. In addition, in this Example, the sulfur content was measured according to the method described in JIS-K2541.

(1) Deep desulfurized light naphtha A (sulfur content
0.5 ppm by weight) Catalyst: Co.Mo/alumina Reaction tower operating conditions: pressure 1.5 MPa, temperature 300 ° C., LH
SV 6.3 hr ^-1 , hydrogen / feed oil ratio 90 m ³ / kl Fractionation conditions: 23 trays, overhead pressure 0.10 MPa, overhead temperature 73 ° C., reflux ratio 0.26 (2) deep desulfurized light naphtha B (Sulfur content 0.1 weight pp
m) Catalyst: Co · Mo / alumina Reaction column operating conditions: pressure 1.5 MPa, temperature 320 ° C., LH
SV 6.3 hr ^-1 , hydrogen / feed oil ratio 90 m ³ / kl Fractionation conditions: 23 trays, overhead pressure 0.10 MPa, overhead temperature 73 ° C., reflux ratio 0.26 (3) Depth desulfurization light naphtha C (Sulfur content 0.008 wt ppm) The above desulfurized light naphtha B was charged in a 20 cc reactor filled with Ni / diatomaceous earth (Ni content 50% by weight) as an adsorption catalyst, at normal pressure, at a temperature of 140 ° C, and at an LHSV of 0.2 hr ^-1 Adsorption desulfurization was performed under the following conditions. (4) Desulfurized light naphtha D (sulfur content: 4.8 weight ppm) Catalyst: Co.Mo/alumina Reaction tower operating conditions: pressure 1.5 MPa, temperature 270 ° C., LH
SV 6.3 hr ^-1 , hydrogen / feed oil ratio 90 m ³ / kl Fractional distillation conditions: 23 plates, tower pressure 0.10 MPa, tower temperature 73 ° C., reflux ratio 0.26

Hydrogen production experiment Steam reforming was performed using a fixed bed flow reactor. Catalyst: 20% by weight of water was added to α-alumina powder, mixed and kneaded in a kneader to form 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, an aqueous solution of zirconium oxychloride (ZrO (OH) Cl) (ZrO
To 2.5g) in O ₂ terms, 3 ruthenium chloride (RuCl
_{3 / nH 2 O) (Ru38} % containing) 0.66 g, cobalt nitrate _{(Co (NO 3) · 36H} 2 O) 2.47g and nitric acid magnesium _{(Mg (NO 3) · 26H} 2 O) 6.3
6 g was added and stirred until dissolved. The total volume of the solution is 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 a Ru of 0.5 on a carrier basis.
% By weight, Zr is 5% by weight in terms of zirconia, and Co is 1.
0% by weight and 2% by weight of Mg in terms of magnesia. Conditions: steam / carbon ratio 2.5, LHSV of feed oil = 5
h ⁻¹ , normal pressure, catalyst layer inlet temperature 500 ° C., catalyst layer outlet temperature 750 ° C. A reaction tube was filled with a reforming catalyst, and under the above conditions, the conversion of the catalyst life (steam reforming) was less than 100%. Evaluated by time. The results are shown in Table 1.

[0021]

[Table 1]

[0022]

As described in detail above, the present invention provides
By using fuel oil for fuel cells containing deep desulfurized light naphtha, it is possible to efficiently produce hydrogen used for fuel cells, and to use reforming catalysts without adversely affecting reforming catalysts and fuel cell electrodes. It is possible to provide a fuel oil for a fuel cell which has little deterioration and is suitable for transportation of automobiles and the like.

Claims (9)

[Claims] 1. A fuel oil for a fuel cell, comprising lightly-desulfurized light naphtha. 2. The fuel oil for a fuel cell according to claim 1, wherein the deep-desulfurized light naphtha contains 0.5 ppm by weight or less of sulfur. 3. The fuel oil for a fuel cell according to claim 1, wherein the deep desulfurized light naphtha contains 0.1 ppm by weight or less of sulfur. 4. Depth desulfurized light naphtha is 0.05 wt ppm
The fuel oil for a fuel cell according to any one of claims 1 to 3, comprising the following sulfur: 5. The fuel oil for a fuel cell according to claim 1, wherein the fuel oil contains at least 10% by volume of deep desulfurized light naphtha and 1 ppm by weight or less of sulfur. 6. The fuel oil according to claim 1, wherein the fuel oil contains at least 50% by volume of deep desulfurized light naphtha and 1 ppm by weight or less of sulfur. 7. The fuel oil according to claim 1, wherein the fuel oil contains at least 50% by volume of deep desulfurized light naphtha and 0.1 wt ppm or less of sulfur. . 8. A method for producing hydrogen from the fuel oil for a fuel cell according to claim 1 without performing desulfurization treatment. 9. A reformer for hydrogen production using the fuel oil for a fuel cell according to claim 1 and having no desulfurizer.