WO2001077267A1

WO2001077267A1 - Fuel for use in fuel cell system

Info

Publication number: WO2001077267A1
Application number: PCT/JP2001/003096
Authority: WO
Inventors: Kenichirou Saitou; Iwao Anzai; Osamu Sadakane; Michiro Matsubara
Original assignee: Nippon Oil Corporation
Priority date: 2000-04-10
Filing date: 2001-04-10
Publication date: 2001-10-18
Also published as: AU4689001A; JP4598897B2

Abstract

A fuel for use in a fuel cell system which contains hydrocarbon compounds having four carbon atoms in an amount of 15 vol % or less, hydrocarbon compounds having five carbon atoms in an amount of 5 vol % or more, hydrocarbon compounds having six carbon atoms in an amount of 10 vol % or more. The fuel exhibits an increased energy output generated per it s weight and per amount of CO2 formed, an improved fuel consumption, a decreased evaporative emission, good handling properties such as good storage stability and a suitable flash point, and reduced calories required for preheating. Further, the fuel allows a fuel cell system using the fuel to keep its initial performance for a long period of time, since it reduces the deterioration of a fuel cell system including a reforming catalyst, a water gas shift reaction catalyst, a carbon monoxide removal catalyst and a fuel cell stack.

Description

Description Fuel technology for fuel cell systems

The present invention relates to a fuel used for a fuel cell system. Background art

In recent years, with the growing sense of crisis for the future global environment, there has been a demand for the development capability of earth-friendly energy supply systems. In particular, reduction of CO 2 to prevent global warming, THC (unreacted carbon in exhaust gas), NOx, PM (particulate matter in exhaust gas: soot, fuel, lubricating oil The ability to achieve a high degree of reduction of harmful substances such as high-boiling points and unburned components of polymers) Specific examples of such a system include an automobile power system that replaces the conventional Otto-diesel system or a power generation system that replaces thermal power.

Thus we have the energy efficiency close to the ideal, it is basically a fuel cell that does not leave waste only H ₂ 0 and C 0 ₂ is, it is expected that the most promising system to meet the needs of 'society. To achieve such a system, it is indispensable to develop not only equipment technology but also the optimal fuel for it.

Conventionally, hydrogen, methanol, and hydrocarbon fuels have been considered as fuels for fuel cell systems.

As a fuel for fuel cell systems, hydrogen is advantageous for tables that do not require a special reformer, but because it is a gas at room temperature, it has problems with storage and mounting on vehicles, etc. Special equipment is required. Also, there is a high risk of ignition, so care must be taken when handling.

On the other hand, methanol is advantageous in that it can be relatively easily reformed to hydrogen, but its power generation per weight is small and it must be handled with care because it is toxic. In addition, since it is corrosive, special equipment is required for storage and supply.

In this way, the fuel for fully utilizing the performance of the fuel cell system has not yet been developed. Not issued. In particular, as the fuel for a fuel cell system, it is often the power generation amount per weight, C 0 ₂ generation amount per power generation force s larger, good fuel economy force S of the entire fuel cell system, evaporative emission (evaporative Emissions, reformed hornworm medium, water gas shift reaction catalyst, carbon monoxide removal catalyst, fuel cell stack, etc., with low deterioration of the fuel cell system, long initial performance, and short system startup time Good handling properties such as storage stability and bow I fire point are required.

In the fuel cell system, since it is important to keep the fuel and reformer at a given temperature, the amount of heat required (the amount of heat that balances the amount of preheat and the amount of heat absorbed and absorbed by the reaction) is subtracted from the amount of power generated. Power generation capacity ^ The power generation capacity of the entire fuel cell system. Therefore, the temperature required for reforming the fuel is low, the power s and the preheating power s are small, which is advantageous.In addition, the starting time of the system is ⁵ ', which is advantageous.The weight required for preheating the fuel is also reduced. It is also necessary that the calorific power is small. Insufficient preheating can result in high levels of unreacted hydrocarbons (THC) in the exhaust gas, not only reducing power generation per weight but also causing air pollution. Conversely, when the same system is operated at the same temperature, the THC in the exhaust gas is small and the conversion rate to hydrogen is high.

In view of such circumstances, an object of the present invention is to provide a fuel suitable for a fuel cell system satisfying the above-mentioned required properties in a well-balanced manner. Disclosure of the invention

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a fuel containing a specific amount of a hydrocarbon compound having a specific carbon number is suitable for a fuel cell system.

That is, the fuel for a fuel cell system according to the present invention is:

(1) The content of hydrocarbon compounds having 4 carbon atoms is 15% by volume or less, the content of hydrocarbon compounds having 5 carbon atoms is 5% by volume or more, and the content of hydrocarbon compounds having 6 carbon atoms is contained. The amount is 10% by volume or more.

The fuel containing the specified amount of the hydrocarbon compound having the specified number of carbon atoms further includes: Those satisfying such additional requirements are more preferable.

(2) Fuel for a fuel cell system having a sulfur content of 50 mass ppm or less.

(3) A fuel for a fuel cell system having a saturated content of 30% by volume or more.

(4) Fuel for a fuel cell system having an olefin content of 35% by volume or less.

(5) A fuel for a fuel cell system having an aromatic content of 50% by volume or less.

(6) Fuel for a fuel cell system in which the proportion of paraffin in the saturated content is 60% by volume or more.

(7) Fuel for fuel cell systems in which the proportion of branched paraffin in the paraffin content is 30% by volume or more. Brief description of the drawings.

FIG. 1 is a flowchart of a steam reforming fuel cell system used for evaluating fuel for a fuel cell system according to the present invention. FIG. 2 is a flowchart of a partial oxidation fuel cell system used for evaluating fuel for a fuel cell system of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the contents of the present invention will be described in more detail.

In the present invention, the amount of the hydrocarbon compound having a specific carbon number is as follows. The content of hydrocarbon compounds with 4 carbon atoms (V (C ₄ )) indicates the content of hydrocarbon compounds with 4 carbon atoms based on the total amount of fuel, and keeps the amount of evaporative gas (evaporation) low. From the point of handling, such as the flash point, it is necessary to have a capacity of 15% by volume or less. It is necessary to have a force of 10% by volume or less. Is most preferred.

The content of the hydrocarbon compounds having 5 carbon atoms (V (C ₅₎₎ indicates the content of hydrocarbon compounds having a carbon number of 5 relative to the fuel total amount, it is often the power generation amount per weight, CO ₂ occurs It is necessary to be at least 5% by volume because power generation per unit is large and fuel efficiency of the fuel cell system as a whole is low. It is more preferably at least 20% by volume, still more preferably at least 20% by volume, and even more preferably at least 25% by volume. Most preferably, it is 30% by volume or more.

The content of hydrocarbon compounds with 6 carbon atoms (V (C ₆ )) indicates the content of hydrocarbon compounds with 6 carbon atoms based on the total fuel amount, indicating that the amount of power generation per weight is large and that CO ₂ Because of the large amount of power generation per unit and the good fuel efficiency of the fuel cell system as a whole, it is necessary to have a capacity of at least 10% by volume, preferably at least 15% by volume, preferably at least 20% by volume. And more preferably at least 25% by volume, and most preferably at least 30% by volume.In the present invention, the content of the hydrocarbon compound having 7 and 8 carbon atoms is preferred. is not particularly limited about the, since power generation force heard per C0 ₂ generation amount, usually the total amount of fuel based on the total amount _{_{(V (C 7 + C 8}} )) as the force element Mashiku of less than 20 volume% used Can be

In the present invention, there is no particular restriction as to the content of the number 10 and higher hydrocarbons I arsenide compound carbon, C0 ₂ generation amount per power generation force s greater fuel economy mosquito Sina overall fuel cell system and Iko, etc. the deterioration of 3ji reforming catalyst can last reduced initial resistance capability s long, the total amount of the number of 10 or more hydrocarbon compounds carbon based fuel total amount (V (C ₁₀ +)) is 20% by volume or less S is preferred, more preferably 10% by volume or less, and most preferably 5% by volume or less.

The above-mentioned V (C ₄ ), V (C ₅ ), V (C ₆ λ, V (C ₇ + C ₈ ) ^ V (C ₁₀ +) are determined by the gas chromatography method shown below. In other words, the column is a methyl silicon capillary column, helium or nitrogen is used as the carrier gas, and a hydrogen ionization detector (FID) is used as the detector. 0.5 to: I. 5 ml Zmin, split ratio 1: 50 to 1: 250, inlet temperature 150 to 250 ° C, initial column temperature—10 to 10 ° C, final column temperature 150 to 250 ° C, It is a value measured at a detector temperature of 150 to 250 ° C.

Although there is no limitation on the sulfur content of the fuel of the present invention, the deterioration of the fuel cell system such as a reforming catalyst, a water gas shift reaction catalyst, a carbon monoxide removal catalyst, a fuel cell stack, etc. is small, and the initial capacity is long. Because it can be maintained for a long time, it should be 50 mass ppm or less based on the total fuel amount. Is more preferably 10 mass ppm or less, still more preferably 1 mass ppm or less, and still more preferably 0.1 mass ppm or less.

Here, when the sulfur content is 1 mass ppm or more, it means the sulfur content measured by JISK 2541 "Crude oil and petroleum products-sulfur content test method", and when it is less than 1 mass ppm, ASTM D4045-96 It means the sulfur content measured by "Standard Test Method for Sul fur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry".

In the present invention, the content of each of the saturated component, the olefin component and the aromatic component is not limited, but the saturated component (V (S)) is 30% by volume or more, and the olefin component (V (0)) is 35% by volume. % Or less, and the aromatic content (V (Ar)) is preferably 50% by volume or less. Hereinafter, these will be individually described.

V (S) is often power generation amount per weight, C0 ₂ generation per generation amount that large heard, good fuel economy force of the entire fuel cell system, THC force s' less that in the exhaust gas, Since the system startup time power S is short, it is preferable that the capacity be 30% by volume or more, more preferably 40% by volume or more, even more preferably 50% by volume or more, and 60% by volume or more. Is still more preferred, 70% by volume or more is even more preferred, 80% by volume or more is even more preferred, and 90% by volume or more is even more preferred. More than 95% by volume is most preferable.

V (0) is often power generation amount per weight, C0 ₂ generation per generation amount that large heard, the deterioration of the reforming catalyst can last reduced initial resistance capability for a long time, that good storage stability For example, the force is preferably 35% by volume or less, more preferably 25% by volume or less, still more preferably 20% by volume or less, and even more preferably 15% by volume or less. Preferably, it is 10% by volume or less.

V (Ar): high power generation per weight, high power generation per CO ₂ generation, good fuel economy as a whole fuel cell system, low THC power in exhaust gas, system Startup time power S is short, power generation per weight is large Since the deterioration of the reforming catalyst is small and the initiality ability can be maintained for a long time, it is preferable that the capacity is 50% by volume or less, more preferably 45% by volume or less, and 40% by volume or less. Is still more preferably 35% by volume or less, still more preferably 30% by volume or less, even more preferably 20% by volume or less, and 10% by volume or less. % Or less, more preferably 5% by volume or less.

It is most preferable because the preferable range of the sulfur content and the preferable range of the aromatic content are satisfied while the deterioration of the reforming catalyst is small and the initial performance can be maintained for a long time.

The above V (S), V (0) and V (A r) are all values measured by the fluorescent indicator adsorption method of JIS K 2 536 “Petroleum products-hydrocarbon type test method”.

Further, in the present invention is not in any way limit for the percentage of the paraffin component in the saturated component of the fuel, it is often the power generation amount per weight, C 0 such as power per ₂ emissions it large heard force> et al The ratio of the paraffin content in the saturated component is preferably at least 60% by volume, more preferably at least 65% by volume, even more preferably at least 70% by volume, and at least 75% by volume. % Or more, still more preferably 80% by volume or more, still more preferably 85% by volume or more, and even more preferably 90% by volume or more. Is even more preferred, and is more preferably 95% by volume or more.

The above-mentioned saturated content and paraffin content are values determined by the above-described gas chromatography method.

Further, no limitation is a bur often power per weight for the percentage of branched paraffins in the paraffinic fraction, that the power generation per C 0 ₂ generation amount is large, overall fuel consumption of a fuel cell system Power S Good, low THC in exhaust gas, short system startup time ⁵ ', etc., it is preferable that the ratio of branched paraffin in paraffin is 30% by volume or more, 50% %, More preferably at least 70% by volume, and most preferably at least 70% by volume.

The above paraffin content and the amount of branched paraffin are determined by the gas chromatography This is a value determined by the luffy method.

There is no particular limitation on the method for producing the fuel of the present invention. Specifically, for example, light naphtha obtained by atmospheric distillation of crude oil, heavy naphtha obtained by atmospheric distillation of crude oil, desulfurized light naphtha obtained by desulfurizing light naphtha, desulfurized heavy obtained by desulfurizing heavy naphtha Alkylates and alkylates obtained by adding (alkylating) lower olefins to isomerized gasoline obtained by converting naphtha and light naphtha to isoparaffin with an isomerizer, and to hydrocarbons such as isobutane. Desulfurized alkylate, desulfurized hydrocarbons such as isobutane and desulfurized low-olefin, low-sulfur alkylate, reformed gasoline obtained by catalytic reforming, and aromatics from female gasoline. Rough rice as extracted residue, light fraction of three gasoline, [medium heavy fraction of high quality gasoline, heavy fraction of reformed gasoline, catalytic cracking method, hydrogenation Cracked gasoline obtained by cracking, cracked gasoline light fraction, cracked gasoline heavy fraction, desulfurized cracked gasoline obtained by desulfurizing cracked gasoline, desulfurized light cracked gasoline obtained by desulfurizing cracked gasoline light fraction, cracked GTL (Gas to Liquids) J obtained by F-T (Fischer-Tropsch) synthesis after cracking heavy sulfur cracked gasoline, natural gas, etc., which is obtained by desulfurizing a heavy fraction of gasoline, into natural gas and carbon monoxide It is produced by using one or more base materials such as light fractions, desulfurized LPG obtained by desulfurizing LPG, etc. In addition, one or more base materials of the above-mentioned base materials are mixed. It can also be produced later by desulfurization by means of hydrogen or adsorption.

Among them, preferred as a base material for producing the fuel of the present invention are desulfurized hydrocarbons such as light naphtha, desulfurized light naphtha, isomerized gasoline, desulfurized alkylate obtained by desulfurizing an alkylate, and desulfurized isobutane. Low sulfur alkylates by low-grade olefins, desulfurized light cracked gasoline obtained by desulfurizing the light fraction of cracked gasoline, light fraction of GTL, and desulfurized LPG obtained by desulfurizing LPG.

The fuel for the fuel cell system of the present invention includes a colorant for identification, an antioxidant for improving oxidative stability, a metal deactivator, a corrosion inhibitor for corrosion prevention, and cleanliness of the fuel line. Additives such as a detergent for maintaining the lubrication and a lubricity improver for improving the lubricity can be added. However, since the deterioration of the reforming catalyst is small and the initial injection capacity S ′ can be maintained for a long time, the colorant is preferably 1 Oppm or less, more preferably 5 ppm or less. For similar reasons, the antioxidant is preferably at most 300 ppm, more preferably at most 200 ppm, even more preferably at most 100 ppm, most preferably at most 1 Opp-m. For the same reason, the metal deactivator is preferably 50 ppm or less, more preferably 30 ppm or less, still more preferably 1 Oppm or less, and most preferably 5 ppm or less. Similarly, since the deterioration of the reforming catalyst is small and the initial performance can be maintained for a long time, the corrosion inhibitor is preferably 5 Oppm or less, more preferably 3 Oppm or less, still more preferably 1 Oppm or less, and most preferably 5 ppm or less. preferable. For the same reason, the detergent is preferably at most 300 ppm, more preferably at most 200 pm, most preferably at most 1,00 ppm. For the same reason, the lubricity improver is preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less.

The fuel of the present invention is used as a fuel for a fuel cell system. The fuel cell system according to the present invention includes a fuel reformer, a carbon monoxide purifying device, a fuel cell, and the like, and the fuel of the present invention is suitably used for any fuel cell system.

The fuel reformer is for reforming the fuel to obtain hydrogen, which is the fuel of the fuel cell. As a reformer, specifically, for example,

(1) A steam reforming reformer that mixes heated and vaporized fuel with steam and reacts by heating in a catalyst such as copper, nickel, platinum, ruthenium, etc., to obtain a product containing hydrogen as a main component.

(2) A partially oxidized reformer that mixes heated and vaporized fuel with air and reacts with or without a catalyst such as copper, nickel, platinum, ruthenium, etc. to obtain a product containing hydrogen as a main component.

(3) The heated and vaporized fuel is mixed with steam and air, and the partial oxidation reforming of (2) is performed in the former stage of the catalyst layer of copper, nickel, platinum, ruthenium, etc., and in the latter stage, the partial oxidation reaction (1) The steam reforming of (1) is carried out by using the heat generation to obtain a product comprising hydrogen as a main component.

And the like. The carbon monoxide purifier removes carbon monoxide contained in the gas generated by the above reformer and becomes a catalyst poison of the fuel cell.

(1) An aqueous solution that mixes reformed gas and heated vaporized steam and reacts in a catalyst such as copper, nickel, platinum, and ruthenium to obtain carbon dioxide and hydrogen as products from carbon monoxide and steam. Gas shift reactor,

(2) A selective oxidation reactor that converts carbon monoxide into carbon dioxide by mixing the reformed gas with compressed air and reacting it in a catalyst such as platinum or ruthenium is mentioned. used.

Specific examples of fuel cells include solid polymer fuel cells (PEFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC). ) And the like. .

Further, the fuel cell system as described above is used for electric vehicles, conventional hybrid vehicles of an engine and electricity, portable power sources, distributed power sources, home power sources, and cogeneration systems. , Example

Table 1 shows the properties and the like of each base material used for each fuel in the examples and comparative examples.

The heat capacity and latent heat of vaporization were determined by the content of each component determined by the gas chromatography method described above, and by the 'I Vo l ■ of the Technical Data Data Book 1 e um Ref in · 1, Chap. 1 Gene ra 1 Data, Table 1 C 1 ”was calculated based on the numerical value per unit weight for each component.

Table 2 shows the properties of each fuel used in Examples and Comparative Examples. Table 1

Replacement form (Rule 26) Table 1 (continued)

Replacement form (Rule 26) 鹏 screw ¾ i ；

Mixing ratio LPG 17% Desulfurized light naphtha 100% 80%

100% isomerized gasoline

Light reformed gasoline 20%

Medium heavy reformed gasoline 30% 15% Heavy reformed gasoline 70% 68% Property Sulfur content ¾ ppm 0.1 0.1 0.3 0.3 0.5 Carbon number ratio

Carbon number 4% by volume 5.4 7.9 2.4 0.0 16.6 Carbon number 5% by volume 42.2 43.7 43.6 0.0 0.0 Carbon number 6% by volume 49.2 45.7 53.6 0.2 0.1 Carbon number 7% by volume 3.1 2.5 0.3 10.9 5.4 Carbon number 8% by volume 0.1 0.1 0.1 14.4 7.2 Carbon number 7 + 8% by volume 3.2 2.6 0.4 25.3 12.6 Carbon number 9 Volume% 0.0 0.0 0.0 51.8 48.4 Carbon number 10 or more Volume% 0.0 0.0 0.0 22.8 21.9 Composition

Saturation content% 98.9 98.5 99.9 1.6 17.9 Olefin content% 0.0 0.4 0.1 0.0 0.1 Aromatic content% 1.1 1.1 0.0 98.3 82.0 Paraffin content% in saturation 92.6 93.9 98.4 98.2 99.9 Branching / raffin content in paraffin % 37.2 42.6 83.5 54.8 35.9 Density g / cm3 0.6564 0.6549 0.6475 0.8804 0.8316 Net calorific value kJ / kg 44820 44850 44798 41180 41738 Heat capacity (liquid) kJ / kg- ° C 2.197 2.203 2.197 1.704 1.780 Heat capacity (gas) kJ / kg- ° C 1.569 1.572 1.582 1.219 1.274 Latent heat of vaporization kJ / kg 344.4 345.1 332.8 319.8 323.3

For each of these fuels, a fuel cell system evaluation test, evaporative gas test, and storage stability test were performed.

Fuel cell system evaluation test

(1) Steam reforming type

The fuel and water were vaporized by electric heating, and led to a reformer filled with a noble metal catalyst and maintained at a specified temperature with an electric heater to generate a reformed gas rich in hydrogen.

The temperature of the reformer is the lowest temperature at which reforming is performed completely in the initial stage of the test.

(The lowest temperature at which the reformed gas does not contain THC and S).

The reformed gas is led to a carbon monoxide treatment unit (water gas shift reaction) together with water vapor, and 3i (converts carbon monoxide in the raw gas to carbon dioxide), and the generated gas is led to a polymer electrolyte fuel cell to generate electricity. Done.

Shown to ₀ Furochiya one bets in Figure 1 of the steam reforming type fuel cell system used for evaluation

(2) Partial oxidation type

The fuel was gasified by electric heating, and the preheated air was charged with a precious metal catalyst and led to a reformer maintained at 110 ° C with an electric heater to generate hydrogen-rich reformed gas. .

The reformed gas is led to a carbon monoxide treatment device (water gas shift reaction) together with water vapor to convert carbon monoxide in the reformed gas into carbon dioxide, and the generated gas is guided to a polymer electrolyte fuel cell to generate electricity. Was.

Figure 2 shows a flowchart of the partial oxidation fuel cell system used for the evaluation.

(3) Evaluation method

Evaluation H _2, CO in the reformed gas generated from the reformer immediately after the start of the test, were measured for C 0 _2, THC amount. Similarly, the evaluation test immediately after the start of H ₂ in the reformed gas generated from the carbon monoxide processor, CO, C 0 _2, THC amount measured immediately after the evaluation test start was performed on and start 1 0 0 hour after the fuel cell We measured the amount of power generation, fuel consumption, and the amount of CO ₂ emitted from the fuel cell. The amount of heat (preheat amount) required to guide each fuel to a predetermined reformer temperature was calculated from the heat capacity and latent heat of vaporization.

In addition, based on these measured values' calculated values and fuel calorific value, the performance degradation rate of the three female catalysts (power generation 100 hours after the start of the test Z power generation immediately after the start of the test), thermal efficiency (power generation immediately after the start of the test) Z fuel calorific value) and preheat amount ratio (preheat amount Z power generation amount) were calculated. Evaporative gas test

A sample filling hose was attached to the filler port of a 20-litre gasoline carrying can, and the attachment part was completely sealed. Each liter was filled with 5 liters of fuel while the vent valve of the can was open. After filling, the air vent valve was closed and left for 30 minutes. After standing, an activated carbon adsorption device was attached to the tip of the air release valve, and the valve was opened. Immediately, 10 liters of each fuel were supplied from the filler port. Five minutes after refueling, leaving the air release valve open, the activated carbon was allowed to absorb steam, and then the weight increase of the activated carbon was measured. The test was performed at a constant temperature of 25 ° C.

Storage stability test

Each fuel was filled with oxygen in a pressure-resistant sealed container, heated to 100 ° C, left for 24 hours while maintaining the temperature, and evaluated by the real gum test method specified in JISK2261 .

Table 3 shows the measured values and calculated values.

鹏鹉 ¾ I

Table 3

1) Minimum temperature at which THC is not contained in the reformed gas

2) Electric energy / fuel calorific value

3) The amount of heat required to bring the fuel to the specified reformer temperature

4) Preheating amount Z electric energy

Industrial applicability

As described above, the fuel for a fuel cell system according to the present invention is a fuel that can obtain high-output electric energy with a small performance deterioration ratio and that satisfies various performances for a fuel cell.

Claims

The scope of the claims

1. The content of hydrocarbon compounds having 4 carbon atoms is 15% by volume or less, the content of hydrocarbon compounds having 5 carbon atoms is 5% by volume or more, and the content of hydrocarbon compounds having 6 carbon atoms is 1. For a fuel cell system having a content of 10% by volume or more.

2. The fuel for a fuel cell system according to claim 1, wherein the sulfur content is 50 mass ppm or less.

3. The fuel for a fuel cell system according to claim 1, wherein the saturated content is 30% by volume or more.

4. The fuel for a fuel cell system according to any one of claims 1 to 3, wherein the olefin content is 35% by volume or less.

5. The fuel for a fuel cell system according to any one of claims 1 to 4, wherein the aromatic component is 50% by volume or less.

6. The fuel for a fuel cell system according to any one of claims 1 to 5, wherein the proportion of the paraffin component in the saturated component is 60% by volume or more. ,

7. The fuel for a fuel cell system according to any one of claims 1 to 6, wherein the proportion of the branched paraffin in the paraffin content is 30% by volume or more.