JP5420455B2 - Method for producing adsorptive desulfurization agent, hydrocarbon oil desulfurization method, and fuel cell system - Google Patents

Description

  The present invention relates to a method for producing an adsorbing desulfurizing agent for hydrocarbon oil, a method for desulfurizing hydrocarbon oil using the adsorbing desulfurizing agent produced by the method, and a fuel cell system, and in particular, mesoporous silica with a modified surface. And a hydrocarbon oil desulfurization method using the adsorptive desulfurization agent.

And CO ₂ gas as a greenhouse gas, from the viewpoint of reducing the emissions of automotive exhaust gases, such as NO _x, further reduction of sulfur content in the fuel oil has been strongly desired by society. In Japan, sulfur has already been regulated to 10 mass ppm or less since 2007 for diesel and gasoline since 2008. On the other hand, recent technological innovations in fuel cells are remarkable. When the hydrogen source is determined for petroleum-based fuel, if the sulfur content in the fuel oil is not reduced to the ppb level, the fuel cell reformer and the electrode catalyst are poisoned by the sulfur content, and the fuel cell system Thus, the desired life is not obtained. Against this background, desulfurization technology for obtaining ultra-low sulfur petroleum fuel oil has been actively researched.

  Most of the difficult desulfurization compounds that are difficult to remove by conventional hydrodesulfurization methods are thiophenes, benzothiophenes, and dibenzothiophenes. In the case of kerosene, the ratio of thiophenes and benzothiophenes is particularly large, and the ratio of thiophenes and benzothiophenes to the total sulfur compounds is often 70% or more as the sulfur content. On the other hand, there is a demand for a method that can be easily and efficiently desulfurized by a simple operation. For example, no reduction treatment or hydrogen is required, no pressure is required, and room temperature to about 150 ° C. Therefore, a desulfurization agent that can efficiently remove dibenzothiophenes at a relatively low temperature is desired.

  On the other hand, activated carbon having a specific pore structure, particularly fibrous activated carbon, has been reported to have high removal performance against dibenzothiophenes contained in light oil and kerosene (see Patent Document 1). However, since the fibrous activated carbon is cottony, the packing density cannot be increased, and therefore, the adsorption performance per unit volume is not high, and the manufacturing process is complicated and the manufacturing cost is extremely high and not economical. Exists.

  In addition, an activated carbon-based desulfurization agent using cheap biomass such as rice husk and having a large number of mesopores and high adsorption desulfurization performance of dibenzothiophenes has been reported (see Patent Documents 2 and 3). However, the activated carbon-based desulfurization agent has a problem that the adsorptive desulfurization performance is not high when the concentration of dibenzothiophenes is low, and the adsorptive desulfurization performance of thiophenes and benzothiophenes is low.

Further, a hydrocarbon oil containing at least one sulfur compound selected from the group consisting of thiophenes, benzothiophenes and dibenzothiophenes, or a hydrocarbon oil further containing an aromatic hydrocarbon, a solid acid and / or A hydrocarbon oil desulfurization method (see Patent Document 4) in which desulfurization is performed by contacting activated carbon carrying a transition metal oxide is also reported. However, in general, there is a problem that solid acids do not have a pore distribution that is favorable for adsorptive desulfurization of hydrocarbon oils. Further, zeolites such as faujasite type have a large specific surface area of about 300 to 600 m ² / g as measured by the nitrogen adsorption method, but the entrance to the crystal pores is as small as about 7 mm, so that thiophenes having many alkyl groups, Benzthiophenes or dibenzothiophenes are difficult to enter into the crystal pores, and the inside of the crystal pores are not effectively used as adsorption sites for these sulfur compounds. On the other hand, solid superacids such as sulfate radical alumina can control the pore structure to some extent, but they have uniform mesopores suitable for the entry of sulfur compounds and are derived from micropores that serve as adsorption sites. The high specific surface area to be obtained has not been achieved.

Further, an adsorptive desulfurization agent in which copper chloride (CuCl) is introduced into mesoporous silica has been studied (Non-patent Document 1). However, the effect of introducing Cu ⁺ was limited even for thiophene which is small in molecule and easy to adsorb and remove.

International Publication No. 2003/097771 JP 2007-284337 A JP 2009-072712 A International Publication No. 2005/073348

W. Dai, Y .; Zhou, S .; Li, W.L. Li, W.L. Su, Y. Sun, L.L. Zhou; Ind. Eng. Chem. Res. , 45 (23), 7892-7896 (2006)

  Therefore, the present invention is suitable as a desulfurization agent for hydrocarbon oil in stationary fuel cell systems such as home use, has a high specific surface area, has uniform mesopores, and has a high adsorptive desulfurization performance. It is an object to provide a manufacturing method.

  As a result of intensive investigations to achieve the above-mentioned object, the present inventor has modified a mesoporous silica having uniform mesopores but having no acid sites by supporting the metal oxide and / or by acid treatment. By forming dots, it was found that adsorption removal of thiophenes, benzothiophenes, or dibenzothiophenes having a large number of alkyl groups contained in hydrocarbon oil became possible, and the present invention was completed.

That is, the present invention includes the following inventions.
(1) a specific surface area of 300~1,000m ² / g, besides, the mesoporous silica having an average pore diameter of 30～100A, hydrocarbon oil to form an acid point and modified by carrying the metal oxide A method for producing an adsorbing desulfurizing agent for hydrocarbon oils , wherein the metal oxide is alumina or zirconia .
(2) Production of the adsorptive desulfurization agent for hydrocarbon oil according to (1) , wherein the metal oxide is supported on the mesoporous silica and modified by acid treatment to form acid sites. Method.
(3) The method for producing an adsorptive desulfurization agent for hydrocarbon oil according to (2) above , wherein the acid treatment is carried out at 750 to 1,000 ° C. after impregnation with sulfuric acid.
(4) A hydrocarbon oil containing at least one sulfur compound selected from the group consisting of thiophenes, benzothiophenes and dibenzothiophenes was produced by the method according to any one of (1) to (3) above. A hydrocarbon oil desulfurization method comprising desulfurization by contacting with an adsorption desulfurization agent for hydrocarbon oil.
(5) The hydrocarbon oil desulfurization method according to (4), wherein the hydrocarbon oil is brought into contact with the adsorptive desulfurization agent at a temperature of 100 ° C. or lower.
(6) A desulfurization means for desulfurizing hydrocarbon oil by the method described in (4) or (5) above and a fuel cell, and the hydrocarbon oil desulfurized by the desulfurization means is used as a raw fuel for the fuel cell A fuel cell system.

  According to the method for producing an adsorptive desulfurization agent for hydrocarbon oil of the present invention, an adsorptive desulfurization agent having a high specific surface area and having uniform mesopores can be obtained. Further, with such an adsorbing desulfurization agent, hydrocarbon oil containing at least one sulfur compound selected from the group consisting of thiophenes, benzothiophenes and dibenzothiophenes can be efficiently removed at a low temperature from room temperature to about 100 ° C. Can be desulfurized. Further, by using it for desulfurization of hydrocarbon oil such as kerosene, which is the raw fuel of the fuel cell, there are advantages that the startup and maintenance of the fuel cell become relatively easy and the fuel cell system can be simplified.

[Mesoporous silica]
The mesoporous silica used in the present invention is a substance having a uniform and regular mesopore with a diameter of 20 to 500 mm made of silicon dioxide (silica). In addition, since the pore wall of mesoporous silica is formed of amorphous silica, mesoporous silica does not have solid acidity.

  In the preparation of mesoporous silica, generally, a surfactant micelle is used as a template (structure directing agent), and the surrounding of the micelle is coated with a silica component to form a regular silica skeleton, followed by firing. The internal surfactant is removed, leaving only the silica skeleton, and regular mesopores are formed. Here, various types are synthesized by changing the type of the surfactant, and the MCM series, the SBA series, and the like are known.

The SBA series is synthesized using a block copolymer polymer that is self-organized as a template, and can be controlled to have a relatively large pore diameter of about 50 to 100 mm. Furthermore, since it has a micropore of 20 mm or less, the specific surface area is large. Typically, there is SBA-15, which has a specific surface area of about 500 to 1,000 m ² / g and a mesopore of about 40 to 80 mm. Its production method is described in the literature (for example, D. Zhao, J. Feng, Q. Huo, N. Melosh, GH Fredrickson, BF Chemmelka and GD Stacky; Science, 279, 548-552 ( 1998), D. Zhao, Q. Huo, J. Feng, BF Chmelka and GD Stucky; J. Am. Chem. Soc., 120, 6024-6036 (1998)). .

In addition, the specific surface area Sa [m ² / g] and the total pore volume Va [ml / g] are usually measured by a nitrogen adsorption method. The nitrogen adsorption method is simple and commonly used, and is described in various documents. Examples of such documents include Kazuhiro Hagio: Shimazu review, 48 (1), 35-49 (1991), ASTM (American Society for Testing and Materials) Standard Test Method D 4365-95, and the like. The average pore diameter D [Å] is expressed by the following formula (1):
D = 4 × Va / Sa × 10 ⁴ (1)
Is required.

The mesoporous silica used in the present invention has a specific surface area of 300 to 1,000 m ² / g, an average pore diameter of 30 to 100 mm, a specific surface area of preferably 450 to 650 m ² / g, and an average pore diameter of 45-60 inches is preferred. When the specific surface area of mesoporous silica used as a raw material is smaller than 300 m ² / g, the produced adsorptive desulfurization agent has few sulfur compound adsorption sites and high desulfurization performance cannot be obtained. On the other hand, when the specific surface area of the mesoporous silica used as a raw material is larger than 1,000 m ² / g, the produced adsorbing desulfurization agent is a sulfur compound having a relatively large molecule such as thiophenes, benzothiophenes, or dibenzothiophenes. There are many pores with extremely small diameters that cannot enter, and the performance of these sulfur compounds as adsorptive desulfurization agents is not high. If the average pore size of mesoporous silica used as a raw material is smaller than 30 mm, the produced adsorbent desulfurization agent inhibits diffusion of sulfur compounds of relatively large molecules such as thiophenes, benzothiophenes, or dibenzothiophenes. When the concentration of the sulfur compound is high, the pores are clogged, and adsorption sites that are not utilized are generated. On the other hand, when the average pore diameter of mesoporous silica used as a raw material is larger than 80 mm, the sulfur compound is adsorbed only up to a distance of about 20 mm from the pore wall. Is not efficient.

[Give acid properties to solid surfaces]
Since the pore walls of the mesoporous silica are formed of amorphous silica, the solid surface does not have acid properties. Therefore, the adsorptive power of thiophenes, benzothiophenes, or dibenzothiophenes contained in the hydrocarbon oil is extremely weak. On the other hand, the present inventors have found that it is effective to modify the surface of the pore wall to impart acid properties in order to increase the adsorption power of these sulfur compounds. Here, as a modification method for imparting acid properties, (1) a method of supporting a metal oxide having solid acid properties such as alumina and zirconia, and / or (2) firing after treatment with an acid such as sulfuric acid. Thus, a method of forming a hydroxyl group is effective.
Whether or not the acid property can be imparted can be confirmed by measuring the acid strength (H ₀ ). The acid strength (H ₀ ) is defined by the ability of an acid point on the catalyst surface to give a proton to a base or the ability to receive an electron pair from a base, and is expressed by a pKa value. It can be measured by a method such as a method. For example, the acid strength of the solid acid catalyst can be directly measured using an acid-base conversion indicator having a known pKa value. Neutral red (H ₀ value: +6.8), 4- (phenylazo) -1-naphthylamine (PANA) (H ₀ value: +4.0), p-dimethylaminoazobenzene (butter yellow) (H ₀ value: +3. 3), 4- (phenylazo) diphenylamine (4-PADPA) (H ₀ value: +1.5), dicinnamylideneacetone (H ₀ value: −3.0), benzylideneacetophenone (chalcone) (H ₀ value: − 5.6), anthraquinone (H ₀ value: -8.2), p-nitrotoluene (H ₀ value: -10.5), 2,4-dinitrotoluene (H ₀ value: -12.8), etc. When the catalyst is immersed in a solution of cyclohexane, benzene or sulfuryl chloride and the indicator is changed to an acidic color on the catalyst surface, the value is equal to or less than the pKa value at which the indicator changes to an acidic color.

[Supporting metal oxide]
The mesoporous silica is impregnated with an impregnating liquid containing a metal component and calcined, whereby the metal oxide can be supported on the mesoporous silica. Type of metals are aluminum, zirconium can impart solid acidity, particularly aluminum and zirconium, the kind of the metal salt is much less expensive.

  An aqueous solution of metal salts can be used as the impregnating solution, and any salt can be used as long as it is a water-soluble salt such as nitrate, sulfate, chloride, organic acid salt. In addition, since the influence of a residual component is little, the aqueous solution of nitrate is especially preferable.

  The firing temperature after the impregnation is not less than the temperature at which the metal salt is decomposed to become a metal oxide, but is usually preferably in the range of 400 to 600 ° C. If the temperature is lower than 400 ° C., decomposition of the metal component may be insufficient. On the other hand, at a temperature higher than 600 ° C., the specific surface area is significantly reduced.

  The amount of metal oxide supported may be an amount that does not block the pores, but is preferably in the range of 5 to 50% by mass, particularly 10 to 40% by mass. When the loading amount is less than 5% by mass, many exposed silica surfaces remain, and the effect of imparting acid properties is not sufficient. On the other hand, when the loading amount is more than 50% by mass, the pores are blocked and the diffusion of the sulfur compound may be inhibited.

[Acid treatment]
The acid treatment may be performed by impregnating an aqueous acid solution and baking. In addition, since it can acid-treat more uniformly, it is especially preferable to dry at about 150-500 degreeC before an acid treatment. Further, the temperature of the aqueous solution during the acid treatment is preferably 0 to 80 ° C, more preferably 5 to 35 ° C.

  As the type of acid, any acid such as sulfuric acid, nitric acid, hydrochloric acid, and organic acid can be used. Sulfuric acid and nitric acid are preferred because they are less affected by residual components. In addition, sulfuric acid is particularly preferable because sulfate radicals can be formed after loading the metal oxide.

  Although the arbitrary density | concentrations can use the density | concentration of an acid, the range of 0.5-8N (normal), especially 1-4N is preferable. When the concentration is less than 0.5N, the effect of acid treatment is small. On the other hand, when the concentration is higher than 8N, damage to the amorphous silica pore walls is increased.

  The amount of the acid impregnated is preferably determined by measuring the water absorption rate of mesoporous silica or metal oxide-supported mesoporous silica and setting the volume to 1 to 5 times, preferably 1.5 to 3 times the water absorption rate, because the acid treatment can be performed uniformly.

  After the impregnation, aging is performed for 3 to 48 hours, preferably 12 to 24 hours. If the time is shorter than 3 hours, the progress of the acid treatment may be insufficient. On the other hand, if the time is longer than 48 hours, the damage to the amorphous silica pore walls is increased. The temperature of the aqueous solution at the time of aging is the same as that during acid treatment, and is preferably 0 to 80 ° C, more preferably 5 to 35 ° C.

  It is more preferable to dry at about 110 to 150 ° C. after aging because the damage of rapid water evaporation during firing is reduced.

  The calcination temperature after impregnating the acid needs to be equal to or higher than the temperature at which the acid decomposes, and is particularly preferably in the range of 750 to 1,000 ° C. At temperatures below 750 ° C., the formation of acid sites is insufficient, and a very small diameter such that sulfur compounds of relatively large molecules such as thiophenes, benzothiophenes, or dibenzothiophenes cannot enter. Many holes remain. On the other hand, at a temperature higher than 1,000 ° C., the specific surface area is significantly reduced.

Metal oxide loading of the present invention, or a specific surface area of mesoporous silica adsorptive desulfurization agent to form with modified acid sites by treating a metal oxide-bearing and acids, 300~900m ² / g, in particular 350~700m A range of ² / g is preferred. When the specific surface area is less than 300 m ² / g, there are few sulfur compound adsorption sites, and high desulfurization performance cannot be obtained. On the other hand, when the specific surface area is greater than 900 m ² / g, there are many pores with extremely small diameters that cannot enter sulfur compounds of relatively large molecules such as thiophenes, benzothiophenes, or dibenzothiophenes. The performance of sulfur compounds as adsorptive desulfurization agents is not high. The average pore diameter of the mesoporous silica-based adsorptive desulfurization agent is preferably in the range of 30 to 80 mm, particularly 40 to 70 mm. When the average pore diameter is smaller than 30 mm, diffusion of sulfur compounds of relatively large molecules such as thiophenes, benzothiophenes, or dibenzothiophenes is inhibited, and pores are blocked when the concentration of sulfur compounds is high. As a result, adsorption sites that are not utilized are generated. On the other hand, if the average pore diameter is larger than 80 mm, the sulfur compound is adsorbed only to a distance of about 20 mm from the pore wall, so that a useless space increases in the pores, which is not efficient. The pore volume of the mesoporous silica-based adsorptive desulfurization agent is preferably in the range of 0.3 to 1.1 ml / g. When the pore volume is smaller than 0.3 ml / g, an adsorptive desulfurization agent having a high specific surface area and a large average pore diameter cannot be obtained. On the other hand, when the pore volume is larger than 1.1 ml / g, the bulk density of the adsorptive desulfurization agent is small, and the adsorptive desulfurization performance per unit volume is lowered.

[Desulfurization method of hydrocarbon oil]
In the hydrocarbon oil desulfurization method of the present invention, the mesoporous silica-based adsorptive desulfurization agent produced by the method of the present invention is brought into contact with the hydrocarbon oil to adsorb and remove sulfur compounds contained in the hydrocarbon oil. In addition, you may combine with another kind of adsorption desulfurization agent.

As a condition for contacting, normal pressure to 1.0 MPaG is preferable, normal pressure to 0.1 MPaG is more preferable, and 0.001 to 0.03 MPaG is particularly preferable. Flow rate is preferably 0.001～100Hr ^-1 at a liquid hourly space velocity (LHSV), 0.01~10hr ^-1 are more preferred. The apparent linear velocity is 1 × 10 ⁻⁷ to 1 × 10 ⁻¹ m / sec, further 5 × 10 ⁻⁷ to 1 × 10 ⁻² m / sec, particularly 1 × 10 ⁻⁶ to 1 × 10 ^{− 3} m / sec is preferred. If the apparent linear velocity is high, the moving speed of the liquid phase itself passing through the packed bed of adsorbent is faster than the adsorption speed (moving speed from the liquid phase to the solid phase), and the liquid phase reaches the outlet of the adsorbing layer. By this time, the adsorbate cannot be completely removed, and the problem that the hydrocarbon oil flows out from the outlet while containing the adsorbate that is not removed easily occurs. Conversely, if the apparent linear velocity is low, the cross-sectional area of the adsorbent layer is relatively large, so the hydrocarbon oil dispersion state is poor, and the hydrocarbon passes through a cross section perpendicular to the flow direction of the adsorbent layer. The oil flow rate (flow rate) is likely to be uneven, and the adsorbate adsorbed in the cross section of the adsorbent layer is likely to be unevenly distributed (unevenness), so the load on the adsorbent becomes uneven and desulfurization is sufficiently efficient. I can't.

  The temperature at which adsorptive desulfurization is carried out (that is, the temperature at which the adsorbent adsorbent and hydrocarbon oil are brought into contact with each other) is preferably 100 ° C. or less, more preferably in the range of −30 to 100 ° C., and particularly preferably in the range of 0 to 80 ° C. . At a temperature lower than −30 ° C., the diffusion rate of the adsorbed substance (adsorbate) in the hydrocarbon oil is remarkably small, and it takes a long time to be adsorbed. Moreover, since the viscosity of hydrocarbon oil becomes high, the pressure loss in a desulfurizer becomes large and it is necessary to make the inlet pressure of a desulfurizer high. Generally, the temperature at which adsorptive desulfurization is performed is particularly preferably 0 ° C. or higher. On the other hand, when the temperature is higher than 100 ° C., the adsorption of dibenzothiophenes is physical adsorption, so that the adsorption amount at equilibrium is remarkably reduced. The higher the temperature, the higher the adsorption rate, but the amount of dibenzothiophene adsorbed at the time of equilibrium decreases, so 80 ° C. or less is particularly preferable.

  In addition, when hydrocarbon oil is used as a hydrogen source for a fuel cell or the like, sulfur contained in the hydrocarbon must be strictly removed because it is a catalyst poison of the reforming catalyst in the hydrogen production process. On the other hand, the adsorptive desulfurization agent produced by the method of the present invention can reduce the sulfur compound to a very small concentration. Therefore, if the adsorptive desulfurization agent produced by the method of the present invention is used, hydrogen can be produced and supplied to the fuel cell without poisoning the reforming catalyst for producing hydrogen.

[Hydrocarbon oil]
The hydrocarbon oil to which the adsorptive desulfurizing agent produced by the method of the present invention is applied is a hydrocarbon oil containing at least one sulfur compound selected from the group consisting of thiophenes, benzothiophenes and dibenzothiophenes. Specific examples of the hydrocarbon oil include kerosene and light oil, and particularly kerosene for fuel cells that needs to be highly desulfurized (at a depth).

  For qualitative and quantitative analysis of these sulfur compounds, Gas Chromatograph (GC) -Flame Photometric Detector (FPD), GC-Atomic Emission Detector (AED), GC- Sulfur Chemiluminescence Detector (SCD), GC-Inductively Coupled Plasma Mass Spectrometer (ICP-MS), etc. can be used, but GC-ICP is used for mass ppb level analysis. -MS is most preferable (see JP 2006-145219 A).

Kerosene is a hydrocarbon oil mainly composed of hydrocarbons having about 12 to 16 carbon atoms, density (15 ° C.) of 0.79 to 0.85 g / cm ³ , and boiling point range of about 150 to 320 ° C. Kerosene contains a lot of paraffinic hydrocarbons, but contains about 0 to 30% by volume of aromatic hydrocarbons and about 0 to 5% by volume of polycyclic aromatics. In general, No. 1 kerosene defined in Japanese Industrial Standard JIS K2203 is used as a fuel for lighting, heating, and kitchen. The No. 1 kerosene has a flash point of 40 ° C. or higher, a 95% distillation temperature of 270 ° C. or lower, a sulfur content of 0.008% by mass or lower, a smoke point of 23 mm or higher (21 mm or higher for cold weather), copper plate corrosion (50 ° C., 3 hours) 1 or less, color (Saebold) +25 or more. Kerosene usually contains a sulfur content of several ppm to 80 ppm by mass and a nitrogen content of several ppm to 10 ppm by mass.

The light oil is a hydrocarbon oil mainly composed of hydrocarbons having about 16 to 20 carbon atoms, a density (15 ° C.) of 0.82 to 0.88 g / cm ³ , and a boiling point range of about 140 to 390 ° C. The light oil contains a lot of paraffinic hydrocarbons, but also contains about 10 to 30% by volume of aromatic hydrocarbons and about 1 to 10% by volume of polycyclic aromatics. The light oil contains a sulfur content from several ppm to 100 ppm by mass and a nitrogen content from several ppm to several tens of ppm.

Thiophenes are heterocyclic compounds containing one or more sulfur atoms as hetero atoms, and the heterocyclic ring is a 5-membered or 6-membered ring and has aromaticity (the heterocyclic ring has two or more double bonds). And a sulfur compound in which the heterocyclic ring is not condensed with the benzene ring and derivatives thereof, and a compound in which the heterocyclic rings are condensed. Thiophene, also called thiofuran, is a sulfur compound having a molecular weight of 84.1 that can be represented by the molecular formula C ₄ H ₄ S. Other typical thiophenes, methylthiophene (thiotolene, molecular formula C ₅ H ₆ S, molecular weight 98.2), thiopyran (penthiophene, molecular formula C ₅ H ₆ S, molecular weight 98.2), thiophthene (molecular formula C ₆ H ₄ S ₂ , molecular weight 140), tetraphenylthiophene (thionesal, molecular formula C ₂₀ H ₂₀ S, molecular weight 388), dithienylmethane (molecular formula C ₉ H ₈ S ₂ , molecular weight 180) and derivatives thereof.

Benzothiophenes are heterocyclic compounds containing one or more sulfur atoms as heteroatoms, and the heterocyclic ring is a five-membered or six-membered ring and has aromaticity (two or more double bonds in the heterocyclic ring). And a sulfur compound in which the heterocyclic ring is condensed with one benzene ring and derivatives thereof. Benzothiophene, also called thionaphthene or thiocoumarone, is a sulfur compound having a molecular weight of 134, which can be represented by the molecular formula C ₈ H ₆ S. Other representative benzothiophenes include methylbenzothiophene, dimethylbenzothiophene, trimethylbenzothiophene, tetramethylbenzothiophene, pentamethylbenzothiophene, hexamethylbenzothiophene, methylethylbenzothiophene, dimethylethylbenzothiophene, trimethylethyl Benzothiophene, tetramethylethylbenzothiophene, pentamethylethylbenzothiophene, methyldiethylbenzothiophene, dimethyldiethylbenzothiophene, trimethyldiethylbenzothiophene, tetramethyldiethylbenzothiophene, methylpropylbenzothiophene, dimethylpropylbenzothiophene, trimethylpropylbenzothiophene , Tetramethylpropylbenzothiophene, penta Chill propyl benzothiophene, methyl ethyl propyl benzothiophene, dimethyl ethyl propyl benzothiophene, trimethyl ethylpropyl benzothiophene, alkyl benzothiophenes such as tetramethyl-ethylpropyl benzothiophene, Chiakuromen (Benzochia -γ- pyran, molecular formula C ₉ H ₈ S, Molecular weight 148), dithiaphthalene (molecular formula C ₈ H ₆ S ₂ , molecular weight 166) and derivatives thereof.

Dibenzothiophenes are heterocyclic compounds containing one or more sulfur atoms as heteroatoms, and the heterocyclic ring is a five-membered or six-membered ring and has aromaticity (two or more double bonds in the heterocyclic ring). And a sulfur compound in which a heterocyclic ring is condensed with two benzene rings and derivatives thereof. Dibenzothiophene is also referred to as diphenylene sulfide, biphenylene sulfide, or diphenylene sulfide, and is a sulfur compound having a molecular weight of 184 that can be represented by the molecular formula C ₁₂ H ₈ S. 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene are well known as difficult desulfurization compounds in hydrodesulfurization. Other representative dibenzothiophenes include trimethyldibenzothiophene, tetramethyldibenzothiophene, pentamethyldibenzothiophene, hexamethyldibenzothiophene, heptamethyldibenzothiophene, octamethyldibenzothiophene, methylethyldibenzothiophene, dimethylethyldibenzothiophene, Trimethylethyldibenzothiophene, tetramethylethyldibenzothiophene, pentamethylethyldibenzothiophene, hexamethylethyldibenzothiophene, heptamethylethyldibenzothiophene, methyldiethyldibenzothiophene, dimethyldiethyldibenzothiophene, trimethyldiethyldibenzothiophene, tetramethyldiethyldibenzothiophene, Pentamethyldiethyldibenzo Offene, hexamethyldiethyldibenzothiophene, heptamethyldiethyldibenzothiophene, methylpropyldibenzothiophene, dimethylpropyldibenzothiophene, trimethylpropyldibenzothiophene, tetramethylpropyldibenzothiophene, pentamethylpropyldibenzothiophene, hexamethylpropyldibenzothiophene, heptamethylpropyl Alkyl dibenzothiophenes such as dibenzothiophene, methylethylpropyldibenzothiophene, dimethylethylpropyldibenzothiophene, trimethylethylpropyldibenzothiophene, tetramethylethylpropyldibenzothiophene, pentamethylethylpropyldibenzothiophene, hexamethylethylpropyldibenzothiophene, thianthre (Diphenylene disulfide, molecular formula C ₁₂ H ₈ S _2, molecular weight 216), thioxanthene (dibenzo thiopyran, diphenylmethane sulfide, molecular formula C ₁₃ H ₁₀ S, molecular weight 198) include and derivatives thereof.

[Fuel cell system]
The fuel cell system of the present invention comprises a desulfurization means for desulfurizing hydrocarbon oil by the above-described method and a fuel cell, and uses the hydrocarbon oil desulfurized by the desulfurization means as a raw fuel of the fuel cell. . Here, as the desulfurization means, a known desulfurizer can be used. For example, the hydrocarbon oil is desulfurized by filling the desulfurizer with the above-described adsorptive desulfurization agent and circulating the hydrocarbon oil. In addition to the desulfurization means and the fuel cell, the fuel cell system of the present invention usually includes a reforming means for reforming the desulfurized hydrocarbon oil to generate a reformed gas containing hydrogen. Electric power is generated by a fuel cell using quality gas. Here, the reforming means is usually filled with a known reforming catalyst.

  As described above, when hydrocarbon oil is used as the raw fuel (hydrogen source) of the fuel cell, sulfur contained in the hydrocarbon oil becomes a catalyst poison of the reforming catalyst in the hydrogen production process. Since the desulfurization method can reduce the sulfur compound to a very small concentration, by incorporating desulfurization means according to the method into the fuel cell system, hydrogen can be produced without poisoning the reforming catalyst for hydrogen production. Can be supplied to. Therefore, the fuel cell system of the present invention can be particularly suitably applied when kerosene or light oil is used as an onboard reformed fuel in a fuel cell vehicle. The fuel cell system of the present invention may be stationary or movable (for example, a fuel cell vehicle). In the fuel cell system of the present invention, the hydrocarbon oil that is a raw fuel for generating hydrogen used in the fuel cell is preferably kerosene or light oil, and kerosene is particularly preferred.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Synthesis of SBA-15]
SBA-15, a mesoporous silica, was synthesized according to the method described in Zhao et al. Amphiphilic triblock copolymer [poly (ethylene glycol) -block-poly (propylene glycol) -block-poly (ethylene glycol), ethylene oxide (EO): propylene oxide (PO): ethylene oxide (EO) = 20 : 70:20, average molecular weight 5,800] Pluronic P-123 (manufactured by Aldrich) was used as a structure directing agent. Further, tetraethyl orthosilicate (TEOS) was used as a silica source. The mass ratio of the copolymer, TEOS, hydrogen chloride and water was 4.0: 8.5: 4.1: 54.5. The copolymer was dissolved in hydrochloric acid (hydrogen chloride and water) and stirred for 4 hours. Then, while stirring the solution, TEOS was added and the temperature was raised to 40 ° C. After aging at 40 ° C. for 24 hours, the contents were transferred to a polypropylene container and heated at 100 ° C. for 24 hours in an air atmosphere to polymerize silica. Further, the precipitated solid was filtered, washed with water, and dried at 100 ° C. overnight. Finally, baking was performed at 500 ° C. for 6 hours in an air atmosphere. The obtained SBA-15 (mesoporous silica) had a specific surface area of 900 m ² / g and an average pore diameter of 51 mm.

[Preparation of alumina-supported SBA-15]
For 100 parts by mass of SBA-15, 44 parts by mass of Al (NO ₃ ) ₃ .9H ₂ O (99.9%, manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in ion-exchanged water and stirred at 60 ° C. The SBA-15 was impregnated and supported. Firing at 500 ° C. for 6 hours gave mesoporous silica-based desulfurization agent A carrying 12% by mass of alumina with respect to SBA-15.

[Preparation of sulfuric acid-treated SBA-15]
SBA-15 was previously dried at 400 ° C. for 1 hour under air flow. 1.1 g of SBA-15 was impregnated with 20 ml of 2N (1 mol / L) sulfuric acid aqueous solution of 7.0 ml (2.3 times the water absorption of 3.0 ml / g) and aged at 20 ° C. for 16 hours. did. After drying at 130 ° C. for 16 hours in an air atmosphere, firing was performed at 900 ° C. for 1 hour under air flow to obtain a mesoporous silica desulfurizing agent B.

[Preparation of sulfate radical-alumina-supported SBA-15]
For 2Og of mesoporous silica-based desulfurization agent A (alumina-supported mesoporous silica), 12.6ml (2.1 times the water absorption of 3.0ml / g) of 2N (1mol / L) sulfuric acid aqueous solution at 20 ° C Impregnation and aging at 20 ° C. for 16 hours. After drying at 130 ° C. for 16 hours in an air atmosphere, calcination was performed at 900 ° C. for 1 hour under air flow to obtain a mesoporous silica-based desulfurization agent C supporting sulfate radical alumina.

(Measurement of acid strength)
The acid strength was measured by the indicator method. Using benzene as a solvent, p-dimethylaminoazobenzene (H ₀ value: +3.3, indicator A), dicinnamylideneacetone (H ₀ value, −3.0, indicator B), anthraquinone (H ₀ value: − 8.2, Indicator C) and p-nitrotoluene (H ₀ value, -10.5, Indicator D) were dissolved. The sample was weighed in an amount of 0.05 g in a 3.5 mL screw tube bottle and dried in a dryer at 150 ° C. for 21 hours. The indicator was quickly added to the screw tube bottle removed from the dryer. The screw tube bottle to which the indicator was added was capped and shaken well, and the color change was observed. The results are shown in Table 1. In addition, the case where there was no change was marked as x, and the case where there was a change was marked as ◯. The acid strength was higher in the order of mesoporous silica-based desulfurizing agent A> mesoporous silica-based desulfurizing agent C> mesoporous silica-based desulfurizing agent B> SAB-15.

[Immersion desulfurization experiment]
SAB-15 dried at 400 ° C. (Comparative Example 1), mesoporous silica-based desulfurizing agent A (Example 1), mesoporous silica-based desulfurizing agent B ( Reference Example 1 ), and mesoporous silica-based desulfurizing agent C (Example 3) ) Was used to conduct immersion desulfurization experiments in kerosene.

The mass ratio (liquid-solid ratio) of kerosene to each desulfurizing agent was set to 30, 120 and 240, and the desulfurizing agent was immersed in kerosene and allowed to stand at 10 ° C. for 10 days or more to obtain an adsorption equilibrium state. Then, kerosene was taken out and the sulfur content was analyzed by combustion oxidation-ultraviolet fluorescence method. From the sulfur content of kerosene before and after immersion, the following formula (2):
Desulfurization rate [%] = 100 × (S1-S2) / S1 (2)
The ratio of the sulfur content adsorbed and removed by the above was calculated as the desulfurization rate [%]. In the formula, S1 and S2 indicate the sulfur content of kerosene before and after soaking, respectively.

  Kerosene (manufactured by Japan Energy) has a boiling range of 158.0 to 271.5 ° C, a 5% distillation point of 170.5 ° C, a 10% distillation point of 175.5 ° C, a 20% distillation point of 183.0 ° C, 30% distillation point 190.0 ° C, 40% distillation point 197.5 ° C, 50% distillation point 206.0 ° C, 60% distillation point 215.0 ° C, 70% distillation point 224.0 ° C, 80% distillation point 234.0 ° C, 90% distillation point 248.0 ° C, 95% distillation point 259.5 ° C, 97% distillation point 269.0 ° C, density (15 ° C) 0.7940 g / ml 16.9 vol% aromatic content, 83.1 vol% saturation content, 6.2 mass ppm sulfur content, 1 mass ppb sulfur content derived from light sulfur compounds (lighter sulfur compounds than thiophene), thiophenes and Benzothiophenes (heavier than thiophene and thiophene and 4-methyldibenzothiophene Sulfur content derived from a lighter sulfur compound than a molecular weight of 198) 5.0 ppm by mass, dibenzothiophenes (sulfur compounds heavier than 4-methyldibenzothiophene and 4-methyldibenzothiophene, heavy with a molecular weight of 198 or more A sulfur content derived from a sulfur compound) of 1.2 mass ppm and a nitrogen content of 1 mass ppm or less was used.

  Table 1 shows the desulfurization rate of the total sulfur content and the desulfurization rate of the heavy sulfur compound as a result of the immersion type desulfurization experiment.

  From Table 1, it can be seen that the mesoporous silica-based desulfurization agent produced by the method of the present invention can obtain a higher desulfurization rate than kerosene containing thiophenes, benzothiophenes and dibenzothiophenes than the comparative example.

〔Test method〕
Note that the physical properties of the desulfurizing agent and kerosene, which are not particularly described above, were measured according to the following test methods.
Distillation property: Measured according to JIS K2254.
Density (15 ° C.): Measured according to JIS K2249.
Hydrocarbon component composition (aromatic content, saturated content, olefin content): Measured according to JPI-5S-49-97.
Sulfur content (total sulfur content): analyzed by combustion oxidation-ultraviolet fluorescence method.
Sulfur compound type analysis (sulfur content in fractions lighter than thiophene, thiophenes and benzothiophenes, dibenzothiophenes): analyzed by GC-ICP-MS.
Nitrogen content: Measured according to the microcoulometric titration method described in JIS K2609.
-Alumina content: An alkali-melted sample was dissolved in an acidic solution and analyzed with ICP-AES (inductively coupled plasma emission spectrometer).
Specific surface area: measured by a nitrogen adsorption method and calculated by a BET (Brunouer-Emmett-Teller) method.
-Pore volume: measured by a nitrogen adsorption method.

Claims (6)

A specific surface area of 300~1,000m ² / g, besides, the mesoporous silica having an average pore diameter of 30～100A, hydrocarbon oil adsorbent for desulfurization of forming acid point was modified by carrying the metal oxide In the method for producing the agent,
The method for producing an adsorptive desulfurization agent for hydrocarbon oil , wherein the metal oxide is alumina or zirconia . The method for producing an adsorptive desulfurization agent for hydrocarbon oil according to claim 1, wherein the mesoporous silica is supported by the metal oxide and modified by acid treatment to form acid sites . The method for producing an adsorptive desulfurization agent for hydrocarbon oil according to claim 2 , wherein the acid treatment is performed at 750 to 1,000 ° C after impregnation with sulfuric acid.   A hydrocarbon oil containing at least one sulfur compound selected from the group consisting of thiophenes, benzothiophenes and dibenzothiophenes, produced by the method according to any one of claims 1 to 3, for adsorptive desulfurization for hydrocarbon oils A hydrocarbon oil desulfurization method comprising desulfurization by contact with an agent.   The hydrocarbon oil desulfurization method according to claim 4, wherein the hydrocarbon oil is brought into contact with the adsorptive desulfurization agent at a temperature of 100 ° C or lower.   A desulfurization means for desulfurizing a hydrocarbon oil by the method according to claim 4 or 5, and a fuel cell, wherein the hydrocarbon oil desulfurized by the desulfurization means is used as a raw fuel of the fuel cell. Fuel cell system.