JP4580071B2 - Desulfurization agent for petroleum hydrocarbons and method for producing hydrogen for fuel cells - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a desulfurizing agent for petroleum hydrocarbons and a method for producing hydrogen for fuel cells. More specifically, the present invention can efficiently remove sulfur content in petroleum hydrocarbons to 0.2 ppm by weight or less, and has a long life, and uses this desulfurization agent. The present invention relates to a method for producing hydrogen for fuel cells by subjecting petroleum hydrocarbons desulfurized to steam reforming.
[0002]
[Prior art]
In recent years, new energy technology has attracted attention due to environmental problems, and fuel cells are attracting attention as one of the new energy technologies. This fuel cell converts chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen, and has a feature of high energy use efficiency. Alternatively, research into practical use is actively conducted for automobiles and the like.
For this fuel cell, types such as a phosphoric acid type, a molten carbonate type, a solid oxide type, and a solid polymer type are known depending on the type of electrolyte used. On the other hand, as a hydrogen source, liquefied natural gas mainly composed of methanol and methane, city gas mainly composed of this natural gas, synthetic liquid fuel using natural gas as a raw material, and petroleum-based LPG, naphtha, kerosene, etc. The use of hydrocarbons has been studied.
[0003]
When fuel cells are used for consumer use or automobiles, the above petroleum hydrocarbons are easy to store and handle and have a supply system such as a gas station or a dealer. As advantageous.
However, petroleum-based hydrocarbons have a problem that the sulfur content is higher than that of methanol or natural gas-based ones. When hydrogen is produced using this petroleum-based hydrocarbon, generally, a method of subjecting the hydrocarbon to steam reforming or partial oxidation reforming in the presence of a reforming catalyst is used. In such a reforming treatment, the reforming catalyst is poisoned by the sulfur content in the hydrocarbon. Therefore, from the viewpoint of catalyst life, the hydrocarbon is subjected to a desulfurization treatment, and the sulfur content is usually reduced. It is important to make it 0.2 ppm or less.
[0004]
As a desulfurization method for petroleum hydrocarbons, many studies have been made so far. For example, a hydrodesulfurization catalyst such as Co-Mo / alumina or Ni-Mo / alumina and a hydrogen sulfide adsorbent such as ZnO are usually used. There is known a method of hydrodesulfurization at a temperature of 200 to 400 ° C. under a pressure of 5 to 5 MPa. This method is a method in which hydrodesulfurization is performed under severe conditions and the sulfur content is removed by hydrogen sulfide, and since it is difficult to reduce the sulfur content to 0.2 ppm by weight or less, the raw material for fuel cells It is difficult to apply to the manufacture of
On the other hand, a nickel-based adsorbent is known as a desulfurizing agent that can adsorb and remove the sulfur content in kerosene under mild conditions without performing a hydrorefining treatment to reduce the sulfur content to 0.2 ppm by weight or less. (Japanese Patent Publication Nos. 6-65602, 7-115842, 7-115843, JP-A-1-188405, 2-275701, 2-204301, (Hei 5-70780, Hei 6-80972, Hei 6-91173, Hei 6-228570).
These nickel-based adsorbents are advantageous to be applied as desulfurization agents to petroleum-based hydrocarbons for fuel cells, but none of them is at a practical level in terms of lifetime as desulfurization agents. In addition, the actual conditions are not clear about the design conditions of adsorbents suitable for petroleum hydrocarbon desulfurization.
[0005]
[Problems to be solved by the invention]
Under such circumstances, the present invention can efficiently remove sulfur in petroleum hydrocarbons to 0.2 ppm by weight or less, and has a long life and is industrially advantageous for desulfurization of petroleum hydrocarbons. It is an object of the present invention to provide an agent and a method for producing hydrogen for a fuel cell by subjecting a petroleum hydrocarbon desulfurized using the desulfurizing agent to steam reforming.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found that a desulfurization agent having a hydrogen adsorption amount of a specific value or more can meet the purpose as a petroleum hydrocarbon desulfurization agent, And it discovered that hydrogen for fuel cells was obtained efficiently by carrying out the hydro-reforming process of the petroleum hydrocarbon which carried out the desulfurization process using this desulfurization agent.
The present invention has been completed based on such findings.
That is, the present invention provides a petroleum hydrocarbon desulfurization agent characterized in that a metal component is supported on a carrier and the hydrogen adsorption amount is 0.4 mmol / g or more.
The present invention also provides a method for producing hydrogen for fuel cells, characterized in that petroleum hydrocarbon is desulfurized using the petroleum hydrocarbon desulfurizing agent and then contacted with a steam reforming catalyst. It is.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The petroleum hydrocarbon desulfurization agent of the present invention has a metal component supported on a carrier and has a hydrogen adsorption amount of 0.4 mmol / g or more. When the hydrogen adsorption amount is less than 0.4 mmol / g, sufficient desulfurization performance is not exhibited and the object of the present invention cannot be achieved. The upper limit of the hydrogen adsorption amount is not particularly limited. However, since it is difficult to produce a very large amount, the hydrogen adsorption amount is in the range of 0.4 to 0.9 mmol / g from the viewpoint of desulfurization performance and production. The range of 0.6 to 0.8 mmol / g is particularly preferable.
[0008]
The hydrogen adsorption amount is a value measured by the following method.
Fill a quartz test tube with 100 mg of desulfurizing agent. Under normal pressure, the temperature is raised to 120 ° C. in a helium gas flow and maintained for 1 hour, and then the helium gas is replaced with hydrogen gas. The temperature is further increased and maintained at 380 ° C. for 1 hour to activate the desulfurizing agent. Next, hydrogen adsorbed at 300 ° C. is removed under vacuum (3 × 10 ⁻³ Torr), and hydrogen adsorption measurement is performed at 20 ° C. The hydrogen adsorption amount was calculated from the pressure change of the introduced hydrogen.
[0009]
In the present invention, as the carrier, a porous carrier is preferable, and a porous inorganic oxide is particularly preferable. Examples of such materials include silica, alumina, silica-alumina, titania, zirconia, magnesia, zinc oxide, white clay, clay, and diatomaceous earth. These may be used alone or in combination of two or more. Of these, silica-alumina is particularly preferred.
Nickel is particularly suitable as a metal component to be supported on these carriers. Moreover, you may mix other metals, such as copper, cobalt, iron, manganese, and chromium, with this nickel as needed.
In the present invention, the supported amount of nickel is preferably 40% by weight or more as metallic nickel based on the total amount of the desulfurizing agent. If the supported amount is less than 40% by weight, sufficient desulfurization performance may not be exhibited. On the other hand, if the loading amount is too large, the proportion of the carrier decreases, which causes a decrease in the mechanical strength and desulfurization performance of the desulfurizing agent. Considering desulfurization performance and mechanical strength, a more preferable loading amount of this nickel metal is in the range of 50 to 70% by weight.
[0010]
The method for supporting the metal component on the carrier is not particularly limited, and any known method such as an impregnation method, a coprecipitation method, or a kneading method can be employed.
A desulfurization agent in which nickel is supported on an alumina-silica support, which is a preferable desulfurization agent of the present invention, can be produced by, for example, a coprecipitation method as shown below.
In this coprecipitation method, first, an acidic aqueous solution or acidic aqueous dispersion containing a nickel source and an aluminum source, and a basic aqueous solution containing a silicon source and an inorganic base are prepared. Examples of the nickel source used in the former acidic aqueous solution or acidic aqueous dispersion include nickel chloride, nickel nitrate, nickel sulfate, and hydrates thereof. Examples of the aluminum source include aluminum hydrates such as aluminum nitrate, pseudoboehmite, boehmite alumina, bayerite, and dibsite, and γ-alumina.
[0011]
On the other hand, the silicon source used in the basic aqueous solution is not particularly limited as long as it is soluble in an alkaline aqueous solution and becomes silica upon firing. For example, orthosilicic acid, metasilicic acid and their sodium salts A potassium salt, water glass, etc. are mentioned. Examples of the inorganic base include alkali metal carbonates and hydroxides.
Next, the acidic aqueous solution or aqueous dispersion thus prepared and the basic aqueous solution are each heated to about 50 to 90 ° C., mixed together, and further maintained at a temperature of about 50 to 90 ° C. To complete the reaction.
Next, the produced solid is sufficiently washed and separated into solid and liquid, or the produced solid is separated into solid and liquid and washed sufficiently, and then this solid is obtained at a temperature of about 80 to 150 ° C. by a known method. Dry at a temperature of A desulfurization agent in which nickel is supported on a silica-alumina carrier is obtained by firing the dried product thus obtained, preferably at a temperature in the range of 200 to 400 ° C. At this time, the type and amount of raw materials to be used, reaction conditions, firing conditions, and the like are selected so that the carrier having the above-described hydrogen adsorption amount is formed and the nickel loading amount becomes a desired value.
[0012]
The desulfurizing agent of the present invention is used as a desulfurizing agent for petroleum hydrocarbons, particularly kerosene. Among kerosene, it is preferable to apply to JIS No. 1 kerosene having a sulfur content of 80 ppm by weight or less. This JIS No. 1 kerosene is obtained by desulfurizing crude kerosene obtained by atmospheric distillation of crude oil. The crude kerosene usually has a high sulfur content, and as such, does not become a JIS No. 1 kerosene, and it is necessary to reduce the sulfur content. As a method for reducing the sulfur content, it is preferable to perform a desulfurization treatment by a hydrorefining method which is generally carried out industrially. In this case, as a desulfurization catalyst, a mixture of transition metals such as nickel, cobalt, molybdenum, tungsten and the like, usually mixed in an appropriate ratio, is supported on a carrier mainly composed of alumina in the form of metal, oxide, sulfide or the like. Things are used. As the reaction conditions, for example, the reaction temperature is 250 to 400 ° C., the pressure is 2 to 10 MPa · G, the hydrogen / oil molar ratio is 2 to 10, and the liquid hourly space velocity (LHSV) is ^{1 to 5} h ⁻¹ .
[0013]
As a method for desulfurizing petroleum hydrocarbons using the sulfur agent of the present invention, for example, the following methods can be used.
First, hydrogen is supplied in advance to the desulfurization tower filled with the desulfurization agent of the present invention, and the desulfurization agent is reduced at a temperature of about 150 to 400 ° C. Next, kerosene No. 1 is preferably passed through the desulfurization tower in an upward or downward flow, and desulfurized under conditions of a temperature of about 130 to 230 ° C., a normal pressure of about ¹ MPa · G, and an LHSV of about 10 h ⁻¹ or less. . At this time, if necessary, a small amount of hydrogen may coexist. By appropriately selecting the desulfurization conditions within the above range, a petroleum hydrocarbon having a sulfur content of 0.2 ppm by weight or less can be obtained.
The method for producing hydrogen for fuel cells of the present invention is a method for producing hydrogen by bringing the petroleum-based hydrocarbon thus desulfurized into contact with a steam reforming catalyst.
[0014]
There is no restriction | limiting in particular as a steam reforming catalyst used in the method of this invention, From the well-known thing conventionally known as a steam reforming catalyst of hydrocarbon, arbitrary things can be selected suitably and can be used. Examples of such a steam reforming catalyst include those in which a noble metal such as nickel, zirconium, ruthenium, rhodium or platinum is supported on a suitable carrier. One of the above supported metals may be supported, or a combination of two or more may be supported. Among these catalysts, those supporting ruthenium (hereinafter referred to as ruthenium catalysts) are preferable, and the effect of suppressing carbon deposition during the steam reforming reaction is great.
In the case of this ruthenium catalyst, the supported amount of ruthenium is preferably in the range of 0.05 to 20% by weight based on the carrier. If the supported amount is less than 0.05% by weight, the steam reforming activity may not be sufficiently exerted. On the other hand, if the supported amount exceeds 20% by weight, the effect of improving the catalytic activity is not so much recognized for the supported amount. Disadvantageous. Considering catalytic activity and economy, the more preferable amount of ruthenium supported is 0.05 to 15% by weight, and particularly preferably 0.1 to 2% by weight.
[0015]
When this ruthenium is supported, it can be supported in combination with other metals as desired. Examples of the other metal include zirconium, cobalt, and magnesium. When ruthenium and zirconium are supported in combination, the supported amount of zirconium is usually 0.5 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 15% by weight, based on the carrier as ZrO _2. It is selected in the range. In the case of supporting ruthenium and cobalt in combination, the amount of cobalt supported is such that the atomic ratio of cobalt to ruthenium is usually 0.01 to 30, preferably 0.1 to 30, and more preferably 0.1 to 10. It is selected to be. Furthermore, when supporting a combination of ruthenium and magnesium, the supported amount of magnesium is usually 0.5 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 15% by weight, based on the carrier as MgO. It is selected in the range.
[0016]
On the other hand, the support is preferably an inorganic oxide, and specifically includes alumina, silica, zirconia, magnesia, and a mixture thereof. Of these, alumina and zirconia are particularly suitable.
One preferred embodiment of the steam reforming catalyst used in the present invention is a catalyst in which ruthenium is supported on zirconia. This zirconia may be zirconia (ZrO ₂ ) as a support or may be stabilized zirconia containing a stabilizing component such as magnesia. As this stabilized zirconia, those containing magnesia, yttria, ceria and the like are suitable.
Another preferred embodiment of the steam reforming catalyst used in the present invention is a catalyst in which cobalt and / or magnesium is supported on an alumina carrier in addition to ruthenium and zirconium, or ruthenium and zirconium. . As the alumina, α-alumina excellent in heat resistance and mechanical strength is particularly preferable.
As reaction conditions in the steam reforming treatment, the ratio S / C (molar ratio) between steam and carbon derived from petroleum hydrocarbon is usually 1.5 to 10, preferably 1.5 to 5, and more preferably. It is selected in the range of 2-4. If the S / C molar ratio is less than 1.5, the amount of hydrogen produced may decrease, and if it exceeds 10, excessive steam is required, heat loss is large, and the efficiency of hydrogen production is unfavorable.
[0017]
Further, it is preferable to perform the steam reforming while keeping the inlet temperature of the steam reforming catalyst layer at 630 ° C. or lower, more preferably 600 ° C. or lower. When the inlet temperature exceeds 630 ° C., thermal decomposition of petroleum hydrocarbons is promoted, and carbon may be deposited on the catalyst or reaction tube wall via the generated radicals, which may make operation difficult. The catalyst layer outlet temperature is not particularly limited, but is preferably in the range of 650 to 800 ° C. If the catalyst layer outlet temperature is less than 650 ° C, the amount of hydrogen produced may not be sufficient. If it exceeds 800 ° C, the reaction apparatus may require a heat-resistant material, which is economically undesirable.
The reaction pressure is usually in the range of normal pressure to 3 MPa, preferably normal pressure to 1 MPa, and LHSV is usually in the range of 0.1 to 100 h ⁻¹ , preferably 0.2 to 50 h ⁻¹ .
In the method for producing hydrogen, CO obtained by the steam reforming has an adverse effect on hydrogen generation. Therefore, it is preferable to remove CO as CO ₂ by reaction.
In this way, hydrogen for fuel cells can be produced efficiently.
[0018]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the desulfurization performance of the desulfurization agent obtained in each example was evaluated according to the following method.
<Desulfurization performance>
A stainless steel reaction tube having an inner diameter of 17 mm is filled with 15 ml of a desulfurizing agent. Next, the temperature is raised to 120 ° C. in a hydrogen stream under normal pressure, held for 1 hour, further heated, and held at 380 ° C. for 1 hour to activate the desulfurizing agent.
Next, the temperature of the reaction tube is maintained at 150 ° C., and supply of JIS No. 1 kerosene having a sulfur content concentration of 65 ppm by weight to the reaction tube at LHSV3h ⁻¹ under normal pressure is started. The sulfur content in the required kerosene after 50 hours has been analyzed to evaluate the desulfurization performance.
The distillation properties of JIS No. 1 kerosene used are as follows.
Initial distillation temperature: 152 ° C
10% distillation temperature: 169 ° C
30% distillation temperature: 184 ° C
50% distillation temperature: 203 ° C
70% distillation temperature: 224 ° C
90% distillation temperature: 254 ° C
95% distillation temperature: 266 ° C
End point: 276 ° C
[0019]
Example 1
Dissolve 50.9 g of nickel chloride in 500 ml of water, add 0.6 g of carrier alumina (pseudo boehmite) to this, add 20 ml of 1 mol / liter nitric acid aqueous solution, and adjust to pH 1, (A) A liquid was prepared.
On the other hand, after 33.1 g of sodium carbonate was dissolved in 500 ml of water, 11.7 g of water glass (SiO ₂ concentration 29% by weight) was added to prepare a liquid (B).
Next, each of the liquids (A) and (B) was heated to 80 ° C., and both were mixed instantaneously, and stirred for 1 hour while maintaining the temperature of the mixed liquid at 80 ° C. Thereafter, the product is sufficiently washed with 60 liters of distilled water, filtered, and then the solid is dried in a 120 ° C. blower dryer for 12 hours and further subjected to a baking treatment at 300 ° C. for 1 hour to obtain silica. -A desulfurization agent having 63% by weight of nickel supported on an alumina support was obtained.
The hydrogen adsorption amount of this desulfurizing agent was 0.75 mmol / g, and the sulfur content in kerosene after 50 hours of desulfurization was 0.2 ppm by weight.
[0020]
Example 2
Water (500 ml) 62.3 g of nickel nitrate was dissolved, 4 g of carrier (silica powder) was added thereto, 20 ml of 1 mol / liter nitric acid aqueous solution was added to adjust to pH 1, and the solution (A) was prepared.
On the other hand, 33.1 g of sodium carbonate was dissolved in 500 ml of water to prepare solution (B).
Thereafter, the same operation as in Example 1 was performed to obtain a desulfurization agent in which 60% by weight of nickel was supported on a silica support.
The hydrogen adsorption amount of this desulfurizing agent was 0.50 mmol / g, and the sulfur content in kerosene after 50 hours of desulfurization was 0.2 ppm by weight.
[0021]
Comparative Example 1
A desulfurizing agent was produced according to the examples described in JP-B-6-65602.
That is, 62.3 g of nickel nitrate was dissolved in 500 ml of water, and 4 g of a carrier (diatomaceous earth) was added thereto to prepare a liquid (A).
On the other hand, 33.1 g of sodium carbonate was dissolved in 500 ml of water to prepare solution (B).
Thereafter, the same operation as in Example 1 was performed to obtain a desulfurization agent in which 67% by weight of nickel was supported on a diatomaceous earth support.
The hydrogen adsorption amount of this desulfurizing agent was 0.32 mmol / g, and the sulfur content in kerosene after 50 hours of desulfurization was 15.2 ppm by weight.
[0022]
Example 3
15 ml of the desulfurizing agent obtained in Example 1 was filled into a stainless steel reaction tube having an inner diameter of 17 mm. Next, the temperature was raised to 120 ° C. in a hydrogen stream under normal pressure, held for 1 hour, further heated, and held at 380 ° C. for 1 hour to activate the desulfurizing agent.
The temperature of the reaction tube was maintained at 0.99 ° C., the JIS1 No. kerosene the sulfur concentration of 65 wt ppm, normal pressure, is passed through the reaction tube at LHSV3h ^-1, further, ruthenium-based reforming catalyst downstream ( Steam reforming treatment was carried out using a reformer filled with 30 ml of a ruthenium support amount of 0.5% by weight.
The reforming treatment conditions are pressure: atmospheric pressure, water vapor / carbon (S / C) molar ratio 2.5, LHSV: 1.5 h ⁻¹ , inlet temperature: 500 ° C., outlet temperature: 750 ° C.
As a result, the conversion rate at the reformer outlet after 150 hours was 100%.
The conversion rate is the formula conversion rate (%) = 100 × B / A
[However, A is the total carbon amount (molar flow rate) in the supplied kerosene per hour, and A = CO + CO ₂ + CH ₄ + 2 × C ₂ fraction + 3 × C ₃ fraction + 4 × C ₄ fraction + 5 × C ₅ fraction B is the total carbon content (molar flow rate) in the reformer outlet gas per hour, B = CO + CO ₂ + CH ₄ . ]
Is a value calculated by The analysis is based on gas chromatography.
Comparative Example 2
In Example 3, kerosene desulfurization treatment and steam reforming treatment were performed in the same manner as in Example 3 except that the desulfurization agent obtained in Comparative Example 1 was used.
As a result, after 24 hours, the conversion rate at the reformer outlet was less than 100%, and oil droplets were confirmed at the reformer outlet after 30 hours.
[0023]
【The invention's effect】
The desulfurization agent for petroleum hydrocarbons of the present invention can efficiently adsorb and remove sulfur content in petroleum hydrocarbons to 0.2 ppm by weight or less, and has a long life. Moreover, hydrogen for fuel cells can be produced effectively by subjecting petroleum hydrocarbons desulfurized using this desulfurizing agent to steam reforming.

Claims (5)

A desulfurization for petroleum hydrocarbons characterized in that nickel is supported on a porous support by 40 wt% or more as metallic nickel based on the total amount of the desulfurizing agent , and the hydrogen adsorption amount is 0.4 mmol / g or more. Agent. The desulfurization agent according to claim 1, wherein the carrier is at least one selected from silica, alumina, silica-alumina, titania, zirconia, magnesia, zinc oxide, clay, clay and diatomaceous earth. The desulfurizing agent according to claim 1 or 2, wherein the petroleum hydrocarbon is kerosene. A method for producing hydrogen for a fuel cell, comprising desulfurizing petroleum hydrocarbons using the desulfurizing agent according to any one of claims 1 to 3 and then contacting with a steam reforming catalyst. The method for producing hydrogen for a fuel cell according to claim 4, wherein the steam reforming catalyst is a ruthenium-based catalyst.