JPWO2007074938A1 - Raw material oil composition for carbon material for electric storage and raw material coal - Google Patents

Abstract

As a raw material oil for the production of activated carbon or needle coke for an electric double layer capacitor electrode, an initial boiling point of 300 ° C. or more obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50 A first heavy oil having a mass fraction of not less than 0.3% and a sulfur content of not more than 0.3% by mass; A heavy oil composition is provided.

Description

  The present invention relates to a raw material oil composition for carbon materials for electricity storage and needle coke, and raw material coal. In particular, the present invention relates to a raw material oil composition and raw material charcoal that provide activated carbon that can easily remove residual alkali metal as activated carbon for an electric double layer capacitor electrode. The present invention also relates to a raw material oil composition and raw material coal suitable for needle coke.

In recent years, carbon materials have been widely used in the field of electric power. As such a carbon material for power storage, for example, activated carbon having a relatively large surface area is used for an electrode of an electric double layer capacitor, and coke having a relatively small surface area is used as a negative electrode of a lithium ion secondary battery. Yes. In particular, electric double layer capacitors are attracting attention as backup power supplies, auxiliary power supplies, etc., and development focusing on the performance of activated carbon as an electrode for electric double layer capacitors has been widely made. Electric double layer capacitors using activated carbon as a polarizable electrode are excellent in electrostatic capacity, so that demand for electric device electrode applications and the like is growing rapidly with the development of the electronics field. Recently, in addition to the miniaturization of conventional memory backup power supplies, development of large-capacity products that can be used for auxiliary power supplies such as motors has been carried out.
As a method for producing these activated carbons, the carbonaceous material is subjected to a gas activation treatment or a chemical activation treatment, for example, an alkali activation treatment using an alkali metal hydroxide as an activation aid, and then an alkali metal or heavy metal from the activation treatment product. In order to remove water, neutralization washing with a strong acid such as hydrochloric acid, nitric acid or sulfuric acid is generally performed.
With the demand for higher performance of electric double layer capacitors, there has been a need to further reduce the residual alkali metal in activated carbon for electric double layer capacitor electrodes. However, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2005-123462), even if the alkali metal can be removed up to a certain level by repeated washing with water and pickling, it is difficult to remove it further. . For this reason, an electric double layer capacitor using a carbon material after alkali activation has an initial capacitor capacity, but has a problem of deterioration over time such that the capacitor capacity greatly decreases when used for a long time.
On the other hand, from the viewpoint of the cleaning operation, the cleaning operation is as simple as possible, that is, it is desirable that the number of times of cleaning is as small as possible in terms of cost. In Patent Document 2 (International Publication No. 2004-011371 pamphlet), an easily activated graphitized carbonaceous material is subjected to an alkali activation treatment, and the obtained activation treatment product is used as hot water, carbonated water, hot hydrochloric acid, aqueous ammonia, hot hydrochloric acid. In addition, although it is described that activated carbon is obtained by washing in order of hot water, since the washing operation is complicated, development of activated carbon having a structure in which residual alkali metal is easily removed has been strongly desired.
On the other hand, needle coke used for the aggregate of graphite electrodes for electric steelmaking is generally manufactured using petroleum heavy oil or coal tar as a raw material. In the process of producing a graphite electrode, first, coke grains and a binder pitch are blended at a predetermined ratio, heat-combined, and then extruded to produce a raw electrode. The raw electrode is fired, graphitized, and then processed to obtain a graphite electrode product.
Since the graphite electrode is used under severe conditions such as a high temperature atmosphere, it is desired that the coefficient of thermal expansion (CTE) is low. That is, the smaller the coefficient of thermal expansion, the smaller the electrode consumption during electric steelmaking, and the cost of electric steelmaking can be reduced.
In addition, the graphitization is a process of heat treatment at about 3000 ° C., and a method using a direct current type furnace (LWG furnace) is common, but when graphitization is performed using an LWG furnace, the rate of temperature rise Therefore, the gas generation speed increases, and an abnormal expansion phenomenon called puffing is likely to occur. When puffing occurs, the electrode is reduced in density, and in some cases, the electrode is damaged.
Therefore, methods for controlling the coefficient of thermal expansion and the quality of puffing during the manufacture of needle coke have been studied, and various methods have been proposed. For example, in Patent Document 3 (Japanese Patent Laid-Open No. 5-105881), an oligomer whose polymerization degree is adjusted is added to a de-QI pitch from which a quinoline insoluble matter is substantially removed from a coal tar-based raw material, and a delayed coking method is used as it is. A method of coking is disclosed. Patent Document 4 (JP-A-5-163491) describes a range in which coal tar heavy oil and petroleum heavy oil have a nitrogen content of 1.0 wt% or less and a sulfur content of 1.4 wt% or less. The raw oil is prepared by mixing the raw oil into a delayed coker, and the raw coke is calcined in the temperature range of 700 to 900 ° C. and cooled once. After that, the method of calcination again in the temperature range of 1200 to 1600 ° C. is disclosed. In Patent Document 5 (Japanese Patent Laid-Open No. 5-202362), when producing coal tar by rapid pyrolysis of coal, the pyrolysis temperature in the reactor is kept at 750 ° C. or higher, and A method is disclosed in which a liquid product is obtained by setting the residence time in the reactor to 5 seconds or less, and the liquid product or pitch contained therein is carbonized. Patent Document 6 (Japanese Patent Application Laid-Open No. 7-3267) discloses a raw material oil obtained by mixing a petroleum heavy oil alone or a mixture of a coal tar heavy oil from which the quinoline insoluble component has been previously removed with the petroleum heavy oil. As a petroleum-based heavy oil, a method using a pre-adjusted so that the content of particles such as ash is in the range of 0.05 wt% to 1 wt% is disclosed. ing.
However, even with the methods described in Patent Documents 3 to 6, the effect of reducing the thermal expansion coefficient or suppressing puffing is not necessarily sufficient, and the quality of the obtained coke is as an aggregate of graphite electrodes for electric steelmaking. The actual situation is that the required level has not yet been reached.

The present inventors have extensively studied from the viewpoint of raw material oil that is a raw material of activated carbon, combined with specific raw material oils, coking them, and then activated carbon obtained by alkali activation of the resulting raw carbon is washed In some cases, it was found that the cleaning liquid can easily enter and exit, and as a result, the residual alkali content in the activated carbon can be reduced and the cleaning operation can be simplified.
Furthermore, the inventors of the present invention have a needle coke obtained by further calcining a raw material coal obtained by coking a raw material oil composition combined with such a specific raw material oil, the coefficient of thermal expansion is sufficiently small, and It was found that puffing is sufficiently suppressed.
In the present invention, “coking coal” refers to a carbide used as a raw material for activated carbon or needle coke, obtained by coking a raw oil such as heavy oil or residual oil.
That is, the present invention has an initial boiling point of 300 ° C. or higher obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0.3% by mass or less. It contains a first heavy oil and a second heavy oil having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less. The present invention relates to a raw material composition for raw coal.
Moreover, this invention relates to the raw material coal obtained by carrying out the coking process of the said raw material oil composition at 300-800 kPa and 400-600 degreeC.
The present invention also relates to activated carbon obtained by activating the raw coal or the raw coal heat-treated product obtained by heat-treating the raw coal at 550 to 900 ° C. under normal pressure with an alkali metal hydroxide.
The present invention also relates to an electric double layer capacitor using the activated carbon as an electrode material.
Furthermore, this invention relates to the needle coke obtained by calcining the said raw coal at 800-1600 degreeC.
[The invention's effect]
Activated carbon obtained by alkali activation of the raw coal obtained by coking the raw oil composition of the present invention obtained by mixing a specific heavy oil is easy for the cleaning solution to enter and exit, and as a result, even in the same cleaning operation Since the amount of the remaining alkali metal is reduced, the cycle characteristics of the electric double layer capacitor using it as an electrode material are improved. Moreover, since the washing operation is simplified, the activated carbon can be manufactured at a lower cost, and its industrial value is extremely large. Further, needle coke obtained by further calcining the raw coal obtained by coking the raw oil composition of the present invention has a sufficiently small coefficient of thermal expansion, and puffing is sufficiently suppressed.

Hereinafter, the present invention will be described in detail.
The raw material composition for raw coal of the present invention is a raw material composition suitable for producing raw material coal for activated carbon or needle coke, and is a heavy oil having specific properties obtained by distillation under reduced pressure of petroleum. (Hereinafter referred to as first heavy oil) and a mixture of heavy oil (hereinafter referred to as second heavy oil) having specific properties obtained by fluid catalytic cracking of hydrocarbon oil.
The first heavy oil according to the present invention has an initial boiling point of 300 ° C. or higher obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0%. .3 heavy oil or less heavy oil.
Examples of petroleums that are raw oils of the first heavy oil include crude oil, atmospheric distillation residue obtained by distillation of crude oil, and mixed oils thereof.
The treatment conditions when the above raw material oil (petroleum) is distilled under reduced pressure are not particularly limited as long as the boiling point, asphaltene content, saturated content and sulfur content of the obtained first heavy oil satisfy the above conditions respectively. Is preferably 30 kPa or less, and the temperature is preferably 400 ° C. or more.
Among the heavy oils obtained as residual oils when distilled under reduced pressure in this way, the heavy oil satisfying the above-mentioned conditions for the boiling point, asphaltene content, saturated content and sulfur content is the first heavy oil according to the present invention. Used as
In other words, the first boiling point of the first heavy oil needs to be 300 ° C. or higher, and preferably 350 ° C. or higher. When the initial boiling point is less than 300 ° C., the yield of the raw coal is reduced, and the raw coal is in an amorphous structure, and the amount of residual alkali metal in the activated carbon obtained by alkali activation of the raw coal is large. It is not preferable. The upper limit of the initial boiling point is preferably 450 ° C. or lower, more preferably 400 ° C. or lower.
The asphaltene content of the first heavy oil needs to be 12% by mass or less, preferably 10% by mass or less, more preferably 9% by mass or less. When the asphaltene content exceeds 12% by mass, early coking proceeds, the resulting raw coal has a coke structure with poor crystallinity, and the amount of residual alkali metal in the activated carbon obtained by activating the raw coal is increased. It is not preferable, and the coefficient of thermal expansion of needle coke obtained by calcination of the raw coal is increased. The lower limit of the asphaltene content is 0% by mass.
Further, the saturated content of the first heavy oil needs to be 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more. When the saturated content is less than 50% by mass, the orientation of the mesophase is deteriorated, and the obtained raw coal becomes a coke structure with poor crystallinity, which is not preferable, and the thermal expansion coefficient of needle coke obtained by calcining the raw coal Is unfavorable because of the high. The upper limit of the saturated content is preferably 85% by mass or less, and more preferably 80% by mass or less.
Further, the sulfur content of the first heavy oil needs to be 0.3% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less. If the sulfur content exceeds 0.3% by mass, there is a tendency to induce early coking, and the resulting raw coal has a coke structure with poor crystallinity, and the amount of residual alkali metal in the activated carbon obtained by alkali activation of the raw coal Is not preferable, and puffing of needle coke obtained by calcination of the raw coal cannot be sufficiently suppressed.
The second heavy oil according to the present invention is a heavy oil having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less.
Here, “fluid catalytic cracking” means a process of cracking a high-boiling fraction using a solid acid catalyst or the like. The fluid catalytic cracking apparatus used for such treatment is also called an FCC (Fluidized Catalytic Cracking) apparatus.
The hydrocarbon oil that is the raw material oil of the second heavy oil is not particularly limited as long as it can obtain a heavy oil whose initial boiling point and sulfur content satisfy the above conditions by fluid catalytic cracking, A hydrocarbon oil having a density at 15 ° C. of 0.8 g / cm ³ or more is preferred.
Such hydrocarbon oils include straight-run gas oil, vacuum gas oil, desulfurized gas oil, desulfurized vacuum gas oil, atmospheric distillation residual oil, vacuum distillation residual oil, shale oil, tar sand bitumen, orinocotal, coal liquefied oil, Examples include hydrorefined products and mixtures thereof. In the present invention, vacuum gas oil and desulfurized vacuum gas oil are particularly preferably used.
The conditions for fluid catalytic cracking are not particularly limited as long as it is possible to obtain a heavy oil whose initial boiling point and sulfur content satisfy the above conditions. For example, the reaction temperature is 480 to 550 ° C., the total pressure is 1 to 3 kg. / Cm ² G (98 to 294 kPa gauge pressure), catalyst / oil ratio of 1 to 20 wt / wt, and contact time of 1 to 10 seconds are preferable.
Examples of the catalyst used for fluid catalytic cracking include a silica / alumina catalyst, a zeolite catalyst, or a catalyst in which a metal such as platinum is supported on these catalysts. A commercial item may be used for these catalysts.
The initial boiling point of the second heavy oil thus obtained is required to be 150 ° C. or higher, preferably 200 ° C. or higher, more preferably 220 ° C. or higher. If the initial boiling point is lower than 150 ° C., the yield of raw coal is reduced, and the resulting raw coal has an amorphous structure, and the remaining alkali metal in the activated carbon obtained by alkali activation of the raw coal is obtained. This is not preferable because the amount increases, and the thermal expansion coefficient of needle coke obtained by calcining the raw coal is increased. The upper limit of the initial boiling point is preferably 350 ° C. or lower, more preferably 300 ° C. or lower.
Further, the sulfur content of the second heavy oil needs to be 0.5% by mass or less, preferably 0.4% by mass or less, more preferably 0.3% by mass or less. If the sulfur content exceeds 0.5 mass%, there is a tendency to induce early coking, and the resulting raw coal has a coke structure with poor crystallinity, and the remaining alkali metal in the activated carbon obtained by alkali activation of the raw coal This is not preferable because the amount increases, and puffing of needle coke obtained by calcining the raw coal cannot be sufficiently suppressed.
The nitrogen content of the second heavy oil is not particularly limited, but is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and further preferably 0.1% by mass or less. . When the nitrogen content is more than 0.2% by mass, the needle coke puffing cannot be sufficiently suppressed.
The raw material oil composition of the present invention is obtained by mixing the first heavy oil and the second heavy oil described above.
As a mixing ratio of the first heavy oil and the second heavy oil, when the activated carbon used for the electrode material for the electric double layer capacitor is manufactured, the content ratio of the first heavy oil is preferably 10 to 10%. It mix | blends so that it may become 80 mass%, More preferably, it is 20-70 mass%, More preferably, it is 30-60 mass%. When producing coke for needle coke, the mixing ratio of the first heavy oil and the second heavy oil is preferably 1 to 50% by mass of the first heavy oil, More preferably, it is 5-50 mass%, and it is still more preferable that it is 15-50 mass%.
Next, the raw material oil composition of the present invention is subjected to coking (carbonization) treatment.
Examples of the method for coking the raw material oil composition include a delayed coking method, a visbreaking method, a flexi coking method, a yurika process, and H-Oil. Among these, the delayed coking method is particularly preferable.
In the delayed coking method, the raw material oil composition is placed in a delayed coker and heat treated under pressure. The pressure of the delayed coker is preferably 300 to 800 kPa. The temperature is preferably 400 to 600 ° C, more preferably 450 to 550 ° C, and the time is preferably 24 to 72 hours, more preferably 36 to 60 hours.
By the coking process, carbide (raw coke) that becomes raw coal is obtained.
In the present invention, the raw material oil composition of the present invention containing the first heavy oil and the second heavy oil has a mosaic structure ratio of 10 μm or less of 5% or less when heat-treated at 500 ° C. It is desirable to provide raw coal that is preferably 2% or less. Here, a small proportion of a mosaic structure of 10 μm or less in the raw coal means that the growth state of liquid crystal called mesophase is good. The mesophase is an intermediate product produced by thermal decomposition and polycondensation accompanying heat treatment of the feedstock oil, and a series of aromatic rings developed along the same plane.
The method for measuring the mosaic structure in the raw coal is as described in “Basics of Carbonization Engineering”, Yuzo Sanada and Sugirou Otani (Ohm), page 147.
Conventionally, when a raw material oil contains a large amount of a saturated component, particularly an aliphatic component, a cross-linking reaction occurs in addition to the polymerization and polycondensation of aromatic components during coking. It is considered that the structure does not grow and the crystallinity is inferior, and as a result, the coefficient of thermal expansion of needle coke is considered to increase, and the amount of residual alkali metal in the activated carbon is considered to increase. In view of this point, it is a surprising result that even when the saturated content of the first heavy oil is 50% by mass or more, a coke having a mosaic structure of 10 μm or less and 5% or less can be obtained.
The raw coal obtained by the coking process can be converted into activated carbon by an alkali activation treatment. Moreover, in carrying out the alkali activation treatment, it is also preferably employed that the raw coal is heat treated at 550 to 900 ° C., preferably 600 to 850 ° C. under an inert atmosphere and normal pressure, and then subjected to the alkali activation treatment.
In the present invention, the activated carbon thus obtained is used as an electrode material for an electric double layer capacitor.
As a method for activating the raw coal or the raw material for heat treatment of raw material carbon, an activation furnace is used to heat the raw material coal or the raw material for heat treatment of raw material coal at 500 to 1200 ° C. together with a metal hydroxide in an atmosphere of nitrogen gas or inert gas. A method can be mentioned. Specific examples of the metal hydroxide include alkali metal hydroxides such as potassium hydroxide, sodium hydroxide and lithium hydroxide, and alkaline earth metal hydroxides such as magnesium hydroxide and barium hydroxide. be able to. Moreover, not only 1 type but 2 or more types can also be used in combination. Of these, potassium hydroxide is particularly preferable because it can efficiently form micropores.
The amount of the raw coal or raw material heat treated carbon and metal hydroxide can be 1 / 0.5 to 1/10 in the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide, Preferably it is 1/1 to 1/5.
By setting the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide to 1 / 0.5 or less, it is possible to sufficiently form micropores in the activated carbon and obtain activated carbon having a sufficient surface area. it can. Moreover, by making the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide to 1/10 or more, the activation reaction can be efficiently performed without lowering the bulk density.
In addition, in the activation reaction, water or the like may coexist in addition to the raw coal or the raw material heat-treated with the raw coal and the metal hydroxide.
In the activation of the raw coal or the raw material for heat treatment of raw coal, the activation temperature may be, for example, in the range of 500 to 1200 ° C, preferably 600 to 1000 ° C, more preferably 600 to 800 ° C. Can do. When the activation temperature is in the above range, activated carbon having sufficient fine pores can be obtained efficiently. The activation treatment time can be appropriately selected in relation to conditions such as temperature, and can include 3 to 6 hours, for example.
Examples of the inert gas at the time of activation include inert gas and nitrogen gas. For example, it is preferable to supply such that the oxygen concentration in the activation atmosphere can be maintained at 100 ppm by volume or less.
The cleaning of the activated material is a cleaning in which the activated material is washed with a cleaning liquid to perform solid-liquid separation. The activated material is immersed in the cleaning liquid and mixed with the cleaning liquid by stirring and heating as necessary, and then the cleaning liquid is removed. The method of doing can be mentioned. As the cleaning liquid, water and an aqueous acid solution are preferably used. For example, cleaning with water, cleaning with an aqueous acid solution, and further cleaning with water can be used in appropriate combination. Preferred examples of the acid aqueous solution include hydrohalic acids such as hydrochloric acid, hydroiodic acid, and hydrobromic acid, and inorganic acids such as sulfuric acid and carbonic acid. Examples of the concentration of the acid aqueous solution include 0.01 to 3N. Cleaning with these cleaning liquids can be repeated a plurality of times as necessary.
After the final washing of the washing step using the washing liquid, solid-liquid separation is performed from the washing liquid, and heating, air drying, and the like are performed as appropriate to remove moisture and obtain dried activated carbon.
The activated carbon obtained by alkali activation of the raw coal obtained by coking the raw material oil composition of the present invention is characterized by less residual alkali metal when washed by the same washing operation compared to conventional activated carbon. Have. The reason why the residual alkali metal is reduced is that the raw coal according to the present invention has a crystal structure in which the metal hydroxide of the activator is easy to enter and escape, and the obtained activated carbon is infiltrated with the cleaning liquid and This is considered to be due to the crystal structure that facilitates escape.
In addition to this, when the activated carbon according to the present invention is used for an electrode of an electric double layer capacitor, it is easy for electrolyte ions to enter and exit during charge and discharge, and the capacitance retention rate in the cycle characteristic test is improved. .
The electric double layer capacitor of the present invention uses activated carbon obtained by activating the raw coal or raw material heat-treated from the raw oil composition of the present invention as an electrode material.
The electrode of the electric double layer capacitor of the present invention is not particularly limited as long as it contains the above activated carbon, but may contain a binder, a conductive agent, etc., and is integrated with the current collector. It may be what you did.
As the binder, known ones can be used, and specifically, fluorinations such as polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and fluoroolefin / vinyl ether copolymer cross-linked polymers. Examples thereof include polymers, celluloses such as carboxymethyl cellulose, vinyl polymers such as polyvinyl pyrrolidone and polyvinyl alcohol, and polyacrylic acid. Specifically, the content of the binder in the electrode material may be 0.1 to 30% by mass.
Specific examples of the conductive agent include powders such as carbon black, acetylene black, and powdered graphite. As content in the electrode material of a electrically conductive agent, the range of 1-50 mass% is preferable, More preferably, it is 2-30 mass%.
In order to produce an electrode using these materials, for example, a method of adding the activated carbon, the binder, and a conductive agent to a solvent that dissolves the binder and applying the slurry as a slurry to a sheet-like current collector, Examples thereof include a method in which the activated carbon, the binder, and the conductive agent are kneaded without using a solvent and pressure-molded at room temperature or under heating.
As the current collector, known materials and shapes can be used, and specific examples include metals such as aluminum, titanium, tantalum, and nickel, and alloys such as stainless steel.
The electric double layer capacitor of the present invention can be produced as a unit cell in which a pair of electrodes are provided with a positive electrode and a negative electrode facing each other through a separator and immersed in an electrolyte solution. As the separator, unemployed cloth made of polypropylene fiber or glass fiber, cellulose paper, or the like can be used.
As the electrolytic solution, an aqueous electrolytic solution or a non-aqueous electrolytic solution can be used, but it is preferable to use a non-aqueous electrolytic solution. Examples of the non-aqueous electrolyte include those obtained by dissolving an electrolyte in an organic solvent. Specific examples of the solvent include propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, and 3-methylsulfolane. Such as sulfolane derivatives, 1,2-dimethoxyethane, etc., dimethoxyethane, acetonitrile, glutaronotolyl, valeronitrile, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, methyl formate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc. Can be used alone or in combination of two or more. Examples of the electrolyte of the electrolytic solution include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, and quaternary phosphonium salts. _{C 2 H 5) 4 NBF 4} , (C 2 H 5) 3 (CH 3) NBF 4, (C 2 H 5) 4 PBF 4, (C 2 H 5) 3 (CH 3) PBF 4 and the like Can do. The electrolyte concentration in the electrolytic solution can be 0.1 to 5 mol / L, and preferably 0.5 to 5 mol / L.
As the shape of the electric double layer capacitor of the present invention, for example, a coin type and a pair of electrodes in which a pair of electrodes of a sheet shape or a disk shape having a thickness of 50 to 500 μm are housed in a metal case via a separator. Examples thereof include a wound type wound through a separator, and a laminated type in which a pair of electrodes provided via a separator are provided in multiple layers.
In the electric double layer capacitor of the present invention, since the activated carbon is used as an electrode material, cycle characteristics are improved, and excellent durability and excellent capacity retention are exhibited.
In addition, the raw coal of the present invention obtained by coking the raw oil composition containing the first heavy oil and the second heavy oil is further calcined in a rotary kiln, a shaft furnace, or the like. Thus, needle coke can be obtained. The temperature during calcination is preferably 800 to 1600 ° C, more preferably 1000 to 1500 ° C. The calcination time is usually 1 to 10 hours, preferably 2 to 6 hours.
The needle coke of the present invention preferably has a sulfur content of 0.5% by mass or less and a nitrogen content of 0.1% by mass or less.
The needle coke of the present invention has a coefficient of thermal expansion that is sufficiently small and puffing is sufficiently suppressed.
As a method for suppressing puffing, the use of an anti-puffing agent (puffing inhibitor) is conventionally known. In this method, the anti-puffing agent becomes an impurity and the quality of the electrode (especially thermal expansion coefficient, density, etc.) May be adversely affected. In contrast, the needle coke of the present invention is very useful in that puffing can be sufficiently suppressed without using an anti-puffing agent and the thermal expansion coefficient of the needle coke can be sufficiently reduced.
The needle coke of the present invention is suitably used as an aggregate of a graphite electrode for electric steelmaking. As a method for producing a graphite electrode product using the needle coke of the present invention, a raw material obtained by adding an appropriate amount of binder pitch to the needle coke of the present invention is heated and mixed, and then extruded to obtain a raw electrode. The method of processing after baking and graphitizing an electrode is mentioned.
In the present invention, “sulfur content” means a value measured in accordance with JIS K2541 in the case of oil, and a value measured in accordance with JIS M 8813 in the case of coke. The “nitrogen content” means a value measured according to JIS K 2609 in the case of oil, and a value measured according to JIS M 8813 in the case of coke. Further, “saturated content” and “asphaltene content” mean values measured using a thin layer chromatograph.

  The raw material oil composition for raw coal of the present invention is suitably used for producing activated carbon for electric double layer capacitor electrodes and also for producing needle coke.

＜実施例３＞
減圧蒸留残渣油Ａと流動接触分解残油Ａとを質量比１：１で混合して原料油組成物Ｃを調製した。この原料油組成物Ｃを試験管に入れ、４００ｋＰａ、５００℃で４０時間熱処理を行いコークス化した。生成した原料炭Ｃを市販の樹脂に埋め込み偏光顕微鏡で観察したところ、１０μｍ以下のモザイク組織は３．５質量％であった。
次に、生成した原料炭Ｃを１０００℃で５時間焼成してか焼コークス（ニードルコークス）を得た。得られたか焼コークスの硫黄分、窒素分及び嵩比重を表２に示す。
また、か焼コークスに石炭系のバインダーピッチを３０質量％加え、押し出し成形器で円柱状のピースを作製した。このピースをマッフル加熱炉を用いて１０００℃で１時間焼成し、焼成後の熱膨張係数を測定した。さらに、ピースを室温から２８００℃まで熱処理し、この過程での膨張の度合いをパッフィングとして測定した。得られた結果を表２に示す。
＜実施例４＞
減圧蒸留残渣油Ａと流動接触分解残油Ａとを質量比１：５で混合して原料油組成物Ｄを調製した。この原料油組成物Ｄを試験管に入れ、４００ｋＰａ、５００℃で４０時間熱処理を行いコークス化した。生成した原料炭Ｄを市販の樹脂に埋め込み偏光顕微鏡で観察したところ、１０μｍ以下のモザイク組織は２．５質量％であった。
次に、生成した原料炭Ｄを１０００℃で５時間焼成してか焼コークスを得た。得られたか焼コークスの硫黄分、窒素分及び嵩比重を表２に示す。
このか焼コークスを用いた以外は実施例３と同様の方法で、円柱状のピースを作製して熱膨張係数およびパッフィングを測定した。その結果を表２に示す。
＜実施例５＞
減圧蒸留残渣油Ａと流動接触分解残油Ａとを質量比１：３で混合して原料油組成物Ｅを調製した。この原料油組成物Ｅを試験管に入れ、４００ｋＰａ、５００℃で４０時間熱処理を行いコークス化した。生成した原料炭Ｅを市販の樹脂に埋め込み偏光顕微鏡で観察したところ、１０μｍ以下のモザイク組織は３．０質量％であった。
次に、生成した原料炭Ｅを１０００℃で５時間焼成してか焼コークスを得た。得られたか焼コークスの硫黄分、窒素分及び嵩比重を表２に示す。
このか焼コークスを用いた以外は実施例３と同様の方法で、円柱状のピースを作製して熱膨張係数およびパッフィングを測定した。その結果を表２に示す。
＜比較例３＞
減圧蒸留残渣油Ａを試験管に入れ、４００ｋＰａ、５００℃で４０時間熱処理を行いコークス化した。次に、生成した原料炭を１０００℃で５時間焼成してか焼コークスを得た。得られたか焼コークスの硫黄分、窒素分及び嵩比重を表２に示す。
このか焼コークスを用いた以外は実施例３と同様の方法で、円柱状のピースを作製して熱膨張係数およびパッフィングを測定した。その結果を表２に示す。
＜比較例４＞
流動接触分解残油Ａを試験管に入れ、４００ｋＰａ、５００℃で４０時間熱処理を行いコークス化した。次に、生成した原料炭を１０００℃で５時間焼成してか焼コークスを得た。得られたか焼コークスの硫黄分、窒素分及び嵩比重を表２に示す。
このか焼コークスを用いた以外は実施例３と同様の方法で、円柱状のピースを作製して熱膨張係数およびパッフィングを測定した。その結果を表２に示す。
＜比較例５＞
硫黄分０．２質量％、窒素分０．３質量％、飽和分４０質量％の低硫黄原油を減圧蒸留し、初留点４１０℃、アスファルテン分１２質量％、飽和分４０質量％、硫黄分０．２質量％、窒素分０．３質量％の減圧蒸留残渣油（以下、「減圧残渣油Ｂ」という。）を得た。この減圧残渣油Ｂを試験管に入れ、４００ｋＰａ、５００℃で４０時間熱処理を行いコークス化した。生成した原料炭を市販の樹脂に埋め込み偏光顕微鏡で観察したところ、１０μｍ以下のモザイク組織は１８％であった。
次に、生成した原料炭を１０００℃で５時間焼成してか焼コークスを得た。得られたか焼コークスの硫黄分、窒素分及び嵩比重を表２に示す。
このか焼コークスを用いた以外は実施例３と同様の方法で、円柱状のピースを作製して熱膨張係数およびパッフィングを測定した。その結果を表２に示す。

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.
<Example 1>
(1) Preparation of raw material oil composition First, an atmospheric distillation residual oil (density 0.92 g / cm ³ , sulfur content 0.35 mass%) was subjected to a heating furnace outlet temperature of 350 ° C. and a pressure of 1.3 kPa. Distilled under reduced pressure, with an initial boiling point of 410 ° C., an asphaltene content of 9% by mass, a saturation content of 61% by mass, a sulfur content of 0.1% by mass, and a nitrogen content of 0.3% by mass (hereinafter referred to as “vacuum distillation residue oil” A ”).
This vacuum distillation residue oil A was put into a test tube and heat-treated at normal pressure and 500 ° C. for 3 hours to be coke. When the produced coke was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 15% by mass.
Further, desulfurized vacuum gas oil (sulfur content: 500 mass ppm, density: 0.88 g / cm ^{3 at} 15 ° C.) is subjected to fluid catalytic cracking to obtain fluid catalytic cracking residual oil (hereinafter referred to as “fluid catalytic cracking residual oil A”). It was. The initial boiling point of the obtained fluid catalytic cracking residual oil A is 210 ° C., the sulfur content is 0.1% by mass, the nitrogen content is 0.1% by mass, the asphaltene content is 0% by mass, and the saturated content is 34% by mass. Met.
This fluid catalytic cracking residual oil A was put in a test tube and heat treated at normal pressure and 500 ° C. for 3 hours to be coke. When the produced coke was embedded in a commercially available resin and observed with a polarizing microscope, the presence of a mosaic structure of 10 μm or less was not recognized.
(2) Preparation of raw coal Next, vacuum distillation residual oil A and fluid catalytic cracking residual oil A were mixed at a mass ratio of 3: 7 to obtain raw oil composition A. This raw material oil composition A was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke to obtain coke (raw coal A). When the produced raw coal A was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.5% by mass.
(3) Activation of coking coal 1 part by mass of coking coal A and 2.5 parts by mass of potassium hydroxide (KOH) are mixed, put in a nickel reaction vessel, heated at 750 ° C. for 1 hour under nitrogen, and activated. Processed.
After the activation treatment, the reaction mixture inside the reaction vessel was cooled to 300 ° C., and carbon dioxide was passed instead of nitrogen to deactivate the metal potassium. Thereafter, 20 kg of water was added to 2 kg of the reaction product, stirred at room temperature for 1 hour, and filtered under pressure. This operation was performed twice. Subsequently, 20 kg of 0.3N hydrochloric acid was added, stirred for 3 hours, and filtered under pressure. An additional 20 kg of water was added, and the mixture was stirred for 1 hour and filtered under pressure. This operation was also performed twice. The obtained solid was dried at 130 ° C. to obtain activated carbon for an electric double layer capacitor. Table 1 shows the specific surface area, residual potassium amount and true specific gravity of the activated carbon.
(4) Production of electric double layer capacitor Activated carbon (0.8 g) obtained above, Ketjen black (0.1 g), and polytetrafluoroethylene (0.1 g) were mixed in a mortar. This mixture was sandwiched between two 0.1 mm thick triacetate films and rolled by passing 20 times between nip rolls having a width of 160 mm, an upper and lower roll interval of 0.7 mm, and a pressure of 23.0 MPa. Two circles having a diameter of 16 mm were punched out from the rolled sheet to obtain carbon electrodes. The carbon electrode was dried in a vacuum dryer for 2 hours.
A cellulose separator having a thickness of 50 μm is sandwiched between two electrodes impregnated with an electrolyte (1 mol of (C ₂ H ₅ ) ₃ (CH ₃ ) NBF ₄ dissolved in 1 liter of propylene carbonate) It enclosed in the coin cell made from SUS316 of diameter 20mm. In this case, a current collector carbon coating applied to the surface of a 20 μm thick aluminum foil was used as a current collector, and the paint side was sandwiched between the carbon electrode and the cell so as to face the carbon electrode.
Table 1 shows the capacitance and cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles) of the electric double layer capacitor cell thus fabricated.
<Example 2>
The vacuum distillation residue oil A and the fluid catalytic cracking residue oil A were mixed at a mass ratio of 6: 4 to obtain a raw material oil composition B. This raw material oil composition B was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke to obtain raw coal B. Except that 1 part by mass of raw coal B and 2.5 parts by mass of potassium hydroxide (KOH) were mixed, put into a nickel reaction vessel, heated at 750 ° C. for 1 hour under nitrogen, and subjected to activation treatment. The same operation as in Example 1 was performed to obtain activated carbon for an electric double layer capacitor. Table 1 shows the specific surface area, residual potassium amount and true specific gravity of the activated carbon. Moreover, the electric double layer capacitor was produced by the same operation as Example 1 using the said activated carbon. Table 1 shows the capacitance of the electric double layer capacitor cell and the cycle characteristics (capacitance retention rate after repeated charging and discharging 1000 times).
<Comparative Example 1>
Only fluid catalytic cracking residual oil A obtained in Example 1 was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke, and then subjected to alkali activation treatment in the same manner as in Example 1 to obtain An electric double layer capacitor was fabricated using activated carbon. Table 1 shows the specific surface area of activated carbon, the amount of residual potassium, the true specific gravity, the capacitance of the electric double layer capacitor cell, and the cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles).
<Comparative example 2>
Only the vacuum distillation residue oil A obtained in Example 1 was subjected to heat treatment at 400 kPa and 500 ° C. for 40 hours to be coke, and then subjected to alkali activation treatment in the same manner as in Example 1 to obtain activated carbon An electric double layer capacitor was fabricated using Table 1 shows the specific surface area of activated carbon, the amount of residual potassium, the true specific gravity, the capacitance of the electric double layer capacitor cell, and the cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles).
As apparent from Table 1, by using the raw material oil composition of the present invention obtained by mixing the vacuum distillation residue oil and the fluid catalytic cracking residue oil, the amount of potassium remaining in the obtained activated carbon is greatly reduced. As a result, the electrostatic capacity retention rate of the electric double layer capacitor using the same can be improved.

<Example 3>
The raw material oil composition C was prepared by mixing the vacuum distillation residual oil A and the fluid catalytic cracking residual oil A at a mass ratio of 1: 1. This raw material oil composition C was put in a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw carbon C was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.5% by mass.
Next, the produced raw coal C was fired at 1000 ° C. for 5 hours to obtain calcined coke (needle coke). Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
Further, 30% by mass of a coal-based binder pitch was added to calcined coke, and a cylindrical piece was produced with an extruder. This piece was fired at 1000 ° C. for 1 hour using a muffle heating furnace, and the thermal expansion coefficient after firing was measured. Furthermore, the piece was heat-treated from room temperature to 2800 ° C., and the degree of expansion in this process was measured as puffing. The obtained results are shown in Table 2.
<Example 4>
The raw material oil composition D was prepared by mixing the vacuum distillation residue oil A and the fluid catalytic cracking residue oil A at a mass ratio of 1: 5. This raw material oil composition D was put in a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw carbon D was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 2.5% by mass.
Next, the produced raw coal D was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.
<Example 5>
The raw material oil composition E was prepared by mixing the vacuum distillation residual oil A and the fluid catalytic cracking residual oil A at a mass ratio of 1: 3. This raw material oil composition E was put in a test tube and heat treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw coal E was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.0% by mass.
Next, the produced raw coal E was calcined at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.
<Comparative Example 3>
The vacuum distillation residue oil A was put into a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. Next, the produced raw coal was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.
<Comparative example 4>
The fluid catalytic cracking residual oil A was put into a test tube and heat treated at 400 kPa and 500 ° C. for 40 hours to be coke. Next, the produced raw coal was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.
<Comparative Example 5>
Low-sulfur crude oil with a sulfur content of 0.2% by mass, nitrogen content of 0.3% by mass and saturation content of 40% by mass is distilled under reduced pressure, initial boiling point 410 ° C., asphaltene content of 12% by mass, saturation content of 40% by mass, sulfur content A vacuum distillation residue oil (hereinafter referred to as “vacuum residue oil B”) having 0.2 mass% and nitrogen content of 0.3 mass% was obtained. This reduced-pressure residue oil B was put in a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw carbon was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 18%.
Next, the produced raw coal was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.

  The present invention relates to a raw material oil composition for carbon materials for electricity storage and needle coke, and raw material coal. In particular, the present invention relates to a raw material oil composition and raw material charcoal that provide activated carbon that can easily remove residual alkali metal as activated carbon for an electric double layer capacitor electrode. The present invention also relates to a raw material oil composition and raw material coal suitable for needle coke.

Recently, carbon materials have been widely used in a charge reservoir field. As such a carbon material for power storage, for example, activated carbon having a relatively large surface area is used for an electrode of an electric double layer capacitor, and coke having a relatively small surface area is used as a negative electrode of a lithium ion secondary battery. Yes. In particular, electric double layer capacitors are attracting attention as backup power supplies, auxiliary power supplies, etc., and development focusing on the performance of activated carbon as an electrode for electric double layer capacitors has been widely made. Electric double layer capacitors using activated carbon as a polarizable electrode are excellent in electrostatic capacity, so that demand for electric device electrode applications and the like is growing rapidly with the development of the electronics field. Recently, in addition to the miniaturization of conventional memory backup power supplies, development of large-capacity products that can be used for auxiliary power supplies such as motors has been carried out.
As a method for producing these activated carbons, the carbonaceous material is subjected to a gas activation treatment or a chemical activation treatment, for example, an alkali activation treatment using an alkali metal hydroxide as an activation aid, and then an alkali metal or heavy metal from the activation treatment product. In order to remove water, neutralization washing with a strong acid such as hydrochloric acid, nitric acid or sulfuric acid is generally performed.
With the demand for higher performance of electric double layer capacitors, there has been a need to further reduce the residual alkali metal in activated carbon for electric double layer capacitor electrodes. However, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2005-123462), even if the alkali metal can be removed up to a certain level by repeated washing with water and pickling, it is difficult to remove it further. . For this reason, an electric double layer capacitor using a carbon material after alkali activation has an initial capacitor capacity, but has a problem of deterioration over time such that the capacitor capacity greatly decreases when used for a long time.

On the other hand, from the viewpoint of the cleaning operation, the cleaning operation is as simple as possible, that is, it is desirable that the number of times of cleaning is as small as possible in terms of cost. In Patent Document 2 (International Publication No. 2004-011371 pamphlet), an easily activated graphitized carbonaceous material is subjected to an alkali activation treatment, and the obtained activation treatment product is used as hot water, carbonated water, hot hydrochloric acid, aqueous ammonia, hot hydrochloric acid. In addition, although it is described that activated carbon is obtained by washing in order of hot water, since the washing operation is complicated, development of activated carbon having a structure in which residual alkali metal is easily removed has been strongly desired.
On the other hand, needle coke used for the aggregate of graphite electrodes for electric steelmaking is generally manufactured using petroleum heavy oil or coal tar as a raw material. In the process of producing a graphite electrode, first, coke grains and a binder pitch are blended at a predetermined ratio, heat-combined, and then extruded to produce a raw electrode. The raw electrode is fired, graphitized, and then processed to obtain a graphite electrode product.
Since the graphite electrode is used under severe conditions such as a high temperature atmosphere, it is desired that the coefficient of thermal expansion (CTE) is low. That is, the smaller the coefficient of thermal expansion, the smaller the electrode consumption during electric steelmaking, and the cost of electric steelmaking can be reduced.
In addition, the graphitization is a process of heat treatment at about 3000 ° C., and a method using a direct current type furnace (LWG furnace) is common, but when graphitization is performed using an LWG furnace, the rate of temperature rise Therefore, the gas generation speed increases, and an abnormal expansion phenomenon called puffing is likely to occur. When puffing occurs, the electrode is reduced in density, and in some cases, the electrode is damaged.

Therefore, methods for controlling the coefficient of thermal expansion and the quality of puffing during the manufacture of needle coke have been studied, and various methods have been proposed. For example, in Patent Document 3 (Japanese Patent Laid-Open No. 5-105881), an oligomer whose polymerization degree is adjusted is added to a de-QI pitch from which a quinoline insoluble matter is substantially removed from a coal tar-based raw material, and a delayed coking method is used as it is. A method of coking is disclosed. Patent Document 4 (JP-A-5-163491) describes a range in which coal tar heavy oil and petroleum heavy oil have a nitrogen content of 1.0 wt% or less and a sulfur content of 1.4 wt% or less. The raw oil is prepared by mixing the raw oil into a delayed coker, and the raw coke is calcined in the temperature range of 700 to 900 ° C. and cooled once. After that, the method of calcination again in the temperature range of 1200 to 1600 ° C. is disclosed. In Patent Document 5 (Japanese Patent Laid-Open No. 5-202362), when producing coal tar by rapid pyrolysis of coal, the pyrolysis temperature in the reactor is kept at 750 ° C. or higher, and A method is disclosed in which a liquid product is obtained by setting the residence time in the reactor to 5 seconds or less, and the liquid product or pitch contained therein is carbonized. Patent Document 6 (Japanese Patent Application Laid-Open No. 7-3267) discloses a raw material oil obtained by mixing a petroleum heavy oil alone or a mixture of a coal tar heavy oil from which the quinoline insoluble component has been previously removed with the petroleum heavy oil. As a petroleum-based heavy oil, a method using a pre-adjusted so that the content of particles such as ash is in the range of 0.05 wt% to 1 wt% is disclosed. ing.
However, even with the methods described in Patent Documents 3 to 6, the effect of reducing the thermal expansion coefficient or suppressing puffing is not necessarily sufficient, and the quality of the obtained coke is as an aggregate of graphite electrodes for electric steelmaking. The actual situation is that the required level has not yet been reached.
JP 2005-123462 A International Publication No. 2004-011371 Pamphlet JP-A-5-105881 JP-A-5-163491 JP-A-5-202362 Japanese Patent Laid-Open No. 7-3267

The present inventors have extensively studied from the viewpoint of raw material oil that is a raw material of activated carbon, combined with specific raw material oils, coking them, and then activated carbon obtained by alkali activation of the resulting raw carbon is washed In some cases, it was found that the cleaning liquid can easily enter and exit, and as a result, the residual alkali content in the activated carbon can be reduced and the cleaning operation can be simplified.
Furthermore, the inventors of the present invention have a needle coke obtained by further calcining a raw material coal obtained by coking a raw material oil composition combined with such a specific raw material oil, the coefficient of thermal expansion is sufficiently small, and It was found that puffing is sufficiently suppressed.
In the present invention, “coking coal” refers to a carbide used as a raw material for activated carbon or needle coke, obtained by coking a raw oil such as heavy oil or residual oil.

That is, the present invention has an initial boiling point of 300 ° C. or higher obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0.3% by mass or less. It contains a first heavy oil and a second heavy oil having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less. The present invention relates to a raw material composition for raw coal.
Moreover, this invention relates to the raw material coal obtained by carrying out the coking process of the said raw material oil composition at 300-800 kPa and 400-600 degreeC.
The present invention also relates to activated carbon obtained by activating the raw coal or the raw coal heat-treated product obtained by heat-treating the raw coal at 550 to 900 ° C. under normal pressure with an alkali metal hydroxide.
The present invention also relates to an electric double layer capacitor using the activated carbon as an electrode material.
Furthermore, this invention relates to the needle coke obtained by calcining the said raw coal at 800-1600 degreeC.

  Activated carbon obtained by alkali activation of the raw coal obtained by coking the raw oil composition of the present invention obtained by mixing a specific heavy oil is easy for the cleaning solution to enter and exit, and as a result, even in the same cleaning operation Since the amount of the remaining alkali metal is reduced, the cycle characteristics of the electric double layer capacitor using it as an electrode material are improved. Moreover, since the washing operation is simplified, the activated carbon can be manufactured at a lower cost, and its industrial value is extremely large. Further, needle coke obtained by further calcining the raw coal obtained by coking the raw oil composition of the present invention has a sufficiently small coefficient of thermal expansion, and puffing is sufficiently suppressed.

Hereinafter, the present invention will be described in detail.
The raw material composition for raw coal of the present invention is a raw material composition suitable for producing raw material coal for activated carbon or needle coke, and is a heavy oil having specific properties obtained by distillation under reduced pressure of petroleum. (Hereinafter referred to as first heavy oil) and a mixture of heavy oil (hereinafter referred to as second heavy oil) having specific properties obtained by fluid catalytic cracking of hydrocarbon oil.

The first heavy oil according to the present invention has an initial boiling point of 300 ° C. or higher obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0%. .3 heavy oil or less heavy oil.
Examples of petroleums that are raw oils of the first heavy oil include crude oil, atmospheric distillation residue obtained by distillation of crude oil, and mixed oils thereof.
The treatment conditions when the above raw material oil (petroleum) is distilled under reduced pressure are not particularly limited as long as the boiling point, asphaltene content, saturated content and sulfur content of the obtained first heavy oil satisfy the above conditions respectively. Is preferably 30 kPa or less, and the temperature is preferably 400 ° C. or more.
Among the heavy oils obtained as residual oils when distilled under reduced pressure in this way, the heavy oil satisfying the above-mentioned conditions for the boiling point, asphaltene content, saturated content and sulfur content is the first heavy oil according to the present invention. Used as
In other words, the first boiling point of the first heavy oil needs to be 300 ° C. or higher, and preferably 350 ° C. or higher. When the initial boiling point is less than 300 ° C., the yield of the raw coal is reduced, and the raw coal is in an amorphous structure, and the amount of residual alkali metal in the activated carbon obtained by alkali activation of the raw coal is large. It is not preferable. The upper limit of the initial boiling point is preferably 450 ° C. or lower, more preferably 400 ° C. or lower.

The asphaltene content of the first heavy oil needs to be 12% by mass or less, preferably 10% by mass or less, more preferably 9% by mass or less. When the asphaltene content exceeds 12% by mass, early coking proceeds, the resulting raw coal has a coke structure with poor crystallinity, and the amount of residual alkali metal in the activated carbon obtained by activating the raw coal is increased. It is not preferable, and the coefficient of thermal expansion of needle coke obtained by calcination of the raw coal is increased. The lower limit of the asphaltene content is 0% by mass.
Further, the saturated content of the first heavy oil needs to be 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more. When the saturated content is less than 50% by mass, the orientation of the mesophase is deteriorated, and the obtained raw coal becomes a coke structure with poor crystallinity, which is not preferable, and the thermal expansion coefficient of needle coke obtained by calcining the raw coal Is unfavorable because of the high. The upper limit of the saturated content is preferably 85% by mass or less, and more preferably 80% by mass or less.
Further, the sulfur content of the first heavy oil needs to be 0.3% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less. If the sulfur content exceeds 0.3% by mass, there is a tendency to induce early coking, and the resulting raw coal has a coke structure with poor crystallinity, and the amount of residual alkali metal in the activated carbon obtained by alkali activation of the raw coal Is not preferable, and puffing of needle coke obtained by calcination of the raw coal cannot be sufficiently suppressed.

The second heavy oil according to the present invention is a heavy oil having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less.
Here, “fluid catalytic cracking” means a process of cracking a high-boiling fraction using a solid acid catalyst or the like. The fluid catalytic cracking apparatus used for such treatment is also called an FCC (Fluidized Catalytic Cracking) apparatus.
The hydrocarbon oil that is the raw material oil of the second heavy oil is not particularly limited as long as it can obtain a heavy oil whose initial boiling point and sulfur content satisfy the above conditions by fluid catalytic cracking, A hydrocarbon oil having a density at 15 ° C. of 0.8 g / cm ³ or more is preferred.
Such hydrocarbon oils include straight-run gas oil, vacuum gas oil, desulfurized gas oil, desulfurized vacuum gas oil, atmospheric distillation residual oil, vacuum distillation residual oil, shale oil, tar sand bitumen, orinocotal, coal liquefied oil, Examples include hydrorefined products and mixtures thereof. In the present invention, vacuum gas oil and desulfurized vacuum gas oil are particularly preferably used.
The conditions for fluid catalytic cracking are not particularly limited as long as it is possible to obtain a heavy oil whose initial boiling point and sulfur content satisfy the above conditions. For example, the reaction temperature is 480 to 550 ° C., the total pressure is 1 to 3 kg. / Cm ² G (98 to 294 kPa gauge pressure), catalyst / oil ratio of 1 to 20 wt / wt, and contact time of 1 to 10 seconds are preferable.
Examples of the catalyst used for fluid catalytic cracking include a silica / alumina catalyst, a zeolite catalyst, or a catalyst in which a metal such as platinum is supported on these catalysts. A commercial item may be used for these catalysts.

The initial boiling point of the second heavy oil thus obtained is required to be 150 ° C. or higher, preferably 200 ° C. or higher, more preferably 220 ° C. or higher. If the initial boiling point is lower than 150 ° C., the yield of raw coal is reduced, and the resulting raw coal has an amorphous structure, and the remaining alkali metal in the activated carbon obtained by alkali activation of the raw coal is obtained. This is not preferable because the amount increases, and the thermal expansion coefficient of needle coke obtained by calcining the raw coal is increased. The upper limit of the initial boiling point is preferably 350 ° C. or lower, more preferably 300 ° C. or lower.
Further, the sulfur content of the second heavy oil needs to be 0.5% by mass or less, preferably 0.4% by mass or less, more preferably 0.3% by mass or less. If the sulfur content exceeds 0.5 mass%, there is a tendency to induce early coking, and the resulting raw coal has a coke structure with poor crystallinity, and the remaining alkali metal in the activated carbon obtained by alkali activation of the raw coal This is not preferable because the amount increases, and puffing of needle coke obtained by calcining the raw coal cannot be sufficiently suppressed.
The nitrogen content of the second heavy oil is not particularly limited, but is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and further preferably 0.1% by mass or less. . When the nitrogen content is more than 0.2% by mass, the needle coke puffing cannot be sufficiently suppressed.

The raw material oil composition of the present invention is obtained by mixing the first heavy oil and the second heavy oil described above.
As a mixing ratio of the first heavy oil and the second heavy oil, when the activated carbon used for the electrode material for the electric double layer capacitor is manufactured, the content ratio of the first heavy oil is preferably 10 to 10%. It mix | blends so that it may become 80 mass%, More preferably, it is 20-70 mass%, More preferably, it is 30-60 mass%. When producing coke for needle coke, the mixing ratio of the first heavy oil and the second heavy oil is preferably 1 to 50% by mass of the first heavy oil, More preferably, it is 5-50 mass%, and it is still more preferable that it is 15-50 mass%.

Next, the raw material oil composition of the present invention is subjected to coking (carbonization) treatment.
Examples of the method for coking the raw material oil composition include a delayed coking method, a visbreaking method, a flexi coking method, a yurika process, and H-Oil. Among these, the delayed coking method is particularly preferable.
In the delayed coking method, the raw material oil composition is placed in a delayed coker and heat treated under pressure. The pressure of the delayed coker is preferably 300 to 800 kPa. The temperature is preferably 400 to 600 ° C, more preferably 450 to 550 ° C, and the time is preferably 24 to 72 hours, more preferably 36 to 60 hours.
By the coking process, carbide (raw coke) that becomes raw coal is obtained.

In the present invention, the raw material oil composition of the present invention containing the first heavy oil and the second heavy oil has a mosaic structure ratio of 10 μm or less of 5% or less when heat-treated at 500 ° C. It is desirable to provide raw coal that is preferably 2% or less. Here, a small proportion of a mosaic structure of 10 μm or less in the raw coal means that the growth state of liquid crystal called mesophase is good. The mesophase is an intermediate product produced by thermal decomposition and polycondensation accompanying heat treatment of the feedstock oil, and a series of aromatic rings developed along the same plane.
The method for measuring the mosaic structure in the raw coal is as described in “Basics of Carbonization Engineering”, Yuzo Sanada and Sugirou Otani (Ohm), page 147.
Conventionally, when a raw material oil contains a large amount of a saturated component, particularly an aliphatic component, a cross-linking reaction occurs in addition to the polymerization and polycondensation of aromatic components during coking. It is considered that the structure does not grow and the crystallinity is inferior, and as a result, the coefficient of thermal expansion of needle coke is considered to increase, and the amount of residual alkali metal in the activated carbon is considered to increase. In view of this point, it is a surprising result that even when the saturated content of the first heavy oil is 50% by mass or more, a coke having a mosaic structure of 10 μm or less and 5% or less can be obtained.

The raw coal obtained by the coking process can be converted into activated carbon by an alkali activation treatment. Moreover, in carrying out the alkali activation treatment, it is also preferably employed that the raw coal is heat treated at 550 to 900 ° C., preferably 600 to 850 ° C. under an inert atmosphere and normal pressure, and then subjected to the alkali activation treatment.
In the present invention, the activated carbon thus obtained is used as an electrode material for an electric double layer capacitor.
As a method for activating the raw coal or the raw material for heat treatment of raw material carbon, an activation furnace is used to heat the raw material coal or the raw material for heat treatment of raw material coal at 500 to 1200 ° C. together with a metal hydroxide in an atmosphere of nitrogen gas or inert gas. A method can be mentioned. Specific examples of the metal hydroxide include alkali metal hydroxides such as potassium hydroxide, sodium hydroxide and lithium hydroxide, and alkaline earth metal hydroxides such as magnesium hydroxide and barium hydroxide. be able to. Moreover, not only 1 type but 2 or more types can also be used in combination. Of these, potassium hydroxide is particularly preferable because it can efficiently form micropores.

The amount of the raw coal or raw material heat treated carbon and metal hydroxide can be 1 / 0.5 to 1/10 in the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide, Preferably it is 1/1 to 1/5.
By setting the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide to 1 / 0.5 or less, it is possible to sufficiently form micropores in the activated carbon and obtain activated carbon having a sufficient surface area. it can. Moreover, by making the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide to 1/10 or more, the activation reaction can be efficiently performed without lowering the bulk density.
In addition, in the activation reaction, water or the like may coexist in addition to the raw coal or the raw material heat-treated with the raw coal and the metal hydroxide.

In the activation of the raw coal or the raw material for heat treatment of raw coal, the activation temperature may be, for example, in the range of 500 to 1200 ° C, preferably 600 to 1000 ° C, more preferably 600 to 800 ° C. Can do. When the activation temperature is in the above range, activated carbon having sufficient fine pores can be obtained efficiently. The activation treatment time can be appropriately selected in relation to conditions such as temperature, and can include 3 to 6 hours, for example.
Examples of the inert gas at the time of activation include inert gas and nitrogen gas. For example, it is preferable to supply such that the oxygen concentration in the activation atmosphere can be maintained at 100 ppm by volume or less.

The cleaning of the activated material is a cleaning in which the activated material is washed with a cleaning liquid to perform solid-liquid separation. The activated material is immersed in the cleaning liquid and mixed with the cleaning liquid by stirring and heating as necessary, and then the cleaning liquid is removed. The method of doing can be mentioned. As the cleaning liquid, water and an aqueous acid solution are preferably used. For example, cleaning with water, cleaning with an aqueous acid solution, and further cleaning with water can be used in appropriate combination. Preferred examples of the acid aqueous solution include hydrohalic acids such as hydrochloric acid, hydroiodic acid, and hydrobromic acid, and inorganic acids such as sulfuric acid and carbonic acid. Examples of the concentration of the acid aqueous solution include 0.01 to 3N. Cleaning with these cleaning liquids can be repeated a plurality of times as necessary.
After the final washing of the washing step using the washing liquid, solid-liquid separation is performed from the washing liquid, and heating, air drying, and the like are performed as appropriate to remove moisture and obtain dried activated carbon.

The activated carbon obtained by alkali activation of the raw coal obtained by coking the raw material oil composition of the present invention is characterized by less residual alkali metal when washed by the same washing operation compared to conventional activated carbon. Have. The reason why the residual alkali metal is reduced is that the raw coal according to the present invention has a crystal structure in which the metal hydroxide of the activator is easy to enter and escape, and the obtained activated carbon is infiltrated with the cleaning liquid and This is considered to be due to the crystal structure that facilitates escape.
In addition to this, when the activated carbon according to the present invention is used for an electrode of an electric double layer capacitor, it is easy for electrolyte ions to enter and exit during charge and discharge, and the capacitance retention rate in the cycle characteristic test is improved. .

The electric double layer capacitor of the present invention uses activated carbon obtained by activating the raw coal or raw material heat-treated from the raw oil composition of the present invention as an electrode material.
The electrode of the electric double layer capacitor of the present invention is not particularly limited as long as it contains the above activated carbon, but may contain a binder, a conductive agent, etc., and is integrated with the current collector. It may be what you did.
As the binder, known ones can be used, and specifically, fluorinations such as polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and fluoroolefin / vinyl ether copolymer cross-linked polymers. Examples thereof include polymers, celluloses such as carboxymethyl cellulose, vinyl polymers such as polyvinyl pyrrolidone and polyvinyl alcohol, and polyacrylic acid. Specifically, the content of the binder in the electrode material may be 0.1 to 30% by mass.
Specific examples of the conductive agent include powders such as carbon black, acetylene black, and powdered graphite. As content in the electrode material of a electrically conductive agent, the range of 1-50 mass% is preferable, More preferably, it is 2-30 mass%.
In order to produce an electrode using these materials, for example, a method of adding the activated carbon, the binder, and a conductive agent to a solvent that dissolves the binder and applying the slurry as a slurry to a sheet-like current collector, Examples thereof include a method in which the activated carbon, the binder, and the conductive agent are kneaded without using a solvent and pressure-molded at room temperature or under heating.
As the current collector, known materials and shapes can be used, and specific examples include metals such as aluminum, titanium, tantalum, and nickel, and alloys such as stainless steel.

  The electric double layer capacitor of the present invention can be produced as a unit cell in which a pair of electrodes are provided with a positive electrode and a negative electrode facing each other through a separator and immersed in an electrolyte solution. As the separator, unemployed cloth made of polypropylene fiber or glass fiber, cellulose paper, or the like can be used.

As the electrolytic solution, an aqueous electrolytic solution or a non-aqueous electrolytic solution can be used, but it is preferable to use a non-aqueous electrolytic solution. Examples of the non-aqueous electrolyte include those obtained by dissolving an electrolyte in an organic solvent. Specific examples of the solvent include propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, and 3-methylsulfolane. Such as sulfolane derivatives, 1,2-dimethoxyethane, etc., dimethoxyethane, acetonitrile, glutaronotolyl, valeronitrile, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, methyl formate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc. Can be used alone or in combination of two or more. Examples of the electrolyte of the electrolytic solution include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, and quaternary phosphonium salts. _{C 2 H 5) 4 NBF 4} , (C 2 H 5) 3 (CH 3) NBF 4, (C 2 H 5) 4 PBF 4, (C 2 H 5) 3 (CH 3) PBF 4 and the like Can do. The electrolyte concentration in the electrolytic solution can be 0.1 to 5 mol / L, and preferably 0.5 to 5 mol / L.

As the shape of the electric double layer capacitor of the present invention, for example, a coin type and a pair of electrodes in which a pair of electrodes of a sheet shape or a disk shape having a thickness of 50 to 500 μm are housed in a metal case via a separator. Examples thereof include a wound type wound through a separator, and a laminated type in which a pair of electrodes provided via a separator are provided in multiple layers.
In the electric double layer capacitor of the present invention, since the activated carbon is used as an electrode material, cycle characteristics are improved, and excellent durability and excellent capacity retention are exhibited.

In addition, the raw coal of the present invention obtained by coking the raw oil composition containing the first heavy oil and the second heavy oil is further calcined in a rotary kiln, a shaft furnace, or the like. Thus, needle coke can be obtained. The temperature during calcination is preferably 800 to 1600 ° C, more preferably 1000 to 1500 ° C. The calcination time is usually 1 to 10 hours, preferably 2 to 6 hours.
The needle coke of the present invention preferably has a sulfur content of 0.5% by mass or less and a nitrogen content of 0.1% by mass or less.
The needle coke of the present invention has a coefficient of thermal expansion that is sufficiently small and puffing is sufficiently suppressed.
As a method for suppressing puffing, the use of an anti-puffing agent (puffing inhibitor) is conventionally known. In this method, the anti-puffing agent becomes an impurity and the quality of the electrode (especially thermal expansion coefficient, density, etc.) May be adversely affected. In contrast, the needle coke of the present invention is very useful in that puffing can be sufficiently suppressed without using an anti-puffing agent and the thermal expansion coefficient of the needle coke can be sufficiently reduced.

The needle coke of the present invention is suitably used as an aggregate of a graphite electrode for electric steelmaking. As a method for producing a graphite electrode product using the needle coke of the present invention, a raw material obtained by adding an appropriate amount of binder pitch to the needle coke of the present invention is heated and mixed, and then extruded to obtain a raw electrode. The method of processing after baking and graphitizing an electrode is mentioned.
In the present invention, “sulfur content” means a value measured in accordance with JIS K2541 in the case of oil, and a value measured in accordance with JIS M 8813 in the case of coke. The “nitrogen content” means a value measured according to JIS K 2609 in the case of oil, and a value measured according to JIS M 8813 in the case of coke. Further, “saturated content” and “asphaltene content” mean values measured using a thin layer chromatograph.

  The raw material oil composition for raw coal of the present invention is suitably used for producing activated carbon for electric double layer capacitor electrodes and also for producing needle coke.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.

<Example 1>
(1) Preparation of raw material oil composition First, an atmospheric distillation residual oil (density 0.92 g / cm ³ , sulfur content 0.35 mass%) was subjected to a heating furnace outlet temperature of 350 ° C. and a pressure of 1.3 kPa. Distilled under reduced pressure, with an initial boiling point of 410 ° C., an asphaltene content of 9% by mass, a saturation content of 61% by mass, a sulfur content of 0.1% by mass, and a nitrogen content of 0.3% by mass (hereinafter referred to as “vacuum distillation residue oil” A ”).
This vacuum distillation residue oil A was put into a test tube and heat-treated at normal pressure and 500 ° C. for 3 hours to be coke. When the produced coke was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 15% by mass.
Further, desulfurized vacuum gas oil (sulfur content: 500 mass ppm, density: 0.88 g / cm ^{3 at} 15 ° C.) is subjected to fluid catalytic cracking to obtain fluid catalytic cracking residual oil (hereinafter referred to as “fluid catalytic cracking residual oil A”). It was. The initial boiling point of the obtained fluid catalytic cracking residual oil A is 210 ° C., the sulfur content is 0.1% by mass, the nitrogen content is 0.1% by mass, the asphaltene content is 0% by mass, and the saturated content is 34% by mass. Met.
This fluid catalytic cracking residual oil A was put in a test tube and heat treated at normal pressure and 500 ° C. for 3 hours to be coke. When the produced coke was embedded in a commercially available resin and observed with a polarizing microscope, the presence of a mosaic structure of 10 μm or less was not recognized.

(2) Preparation of raw coal Next, vacuum distillation residual oil A and fluid catalytic cracking residual oil A were mixed at a mass ratio of 3: 7 to obtain raw oil composition A. This raw material oil composition A was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke to obtain coke (raw coal A). When the produced raw coal A was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.5% by mass.

(3) Activation of coking coal 1 part by mass of coking coal A and 2.5 parts by mass of potassium hydroxide (KOH) are mixed, put in a nickel reaction vessel, heated at 750 ° C. for 1 hour under nitrogen, and activated. Processed.
After the activation treatment, the reaction mixture inside the reaction vessel was cooled to 300 ° C., and carbon dioxide was passed instead of nitrogen to deactivate the metal potassium. Thereafter, 20 kg of water was added to 2 kg of the reaction product, stirred at room temperature for 1 hour, and filtered under pressure. This operation was performed twice. Subsequently, 20 kg of 0.3N hydrochloric acid was added, stirred for 3 hours, and filtered under pressure. An additional 20 kg of water was added, and the mixture was stirred for 1 hour and filtered under pressure. This operation was also performed twice. The obtained solid was dried at 130 ° C. to obtain activated carbon for an electric double layer capacitor. Table 1 shows the specific surface area, residual potassium amount and true specific gravity of the activated carbon.

(4) Production of electric double layer capacitor Activated carbon (0.8 g) obtained above, Ketjen black (0.1 g), and polytetrafluoroethylene (0.1 g) were mixed in a mortar. This mixture was sandwiched between two 0.1 mm thick triacetate films and rolled by passing 20 times between nip rolls having a width of 160 mm, an upper and lower roll interval of 0.7 mm, and a pressure of 23.0 MPa. Two circles having a diameter of 16 mm were punched out from the rolled sheet to obtain carbon electrodes. The carbon electrode was dried in a vacuum dryer for 2 hours.
A cellulose separator having a thickness of 50 μm is sandwiched between two electrodes impregnated with an electrolytic solution (one mole of (C ₂ H ₅ ) ₃ (CH ₃ ) NBF ₄ dissolved in 1 liter of propylene carbonate) It was enclosed in a SUS316 coin cell having a diameter of 20 mm. In this case, a current collector carbon coating applied to the surface of a 20 μm thick aluminum foil was used as a current collector, and the paint side was sandwiched between the carbon electrode and the cell so as to face the carbon electrode.
Table 1 shows the capacitance and cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles) of the electric double layer capacitor cell thus fabricated.

<Example 2>
The vacuum distillation residue oil A and the fluid catalytic cracking residue oil A were mixed at a mass ratio of 6: 4 to obtain a raw material oil composition B. This raw material oil composition B was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke to obtain raw coal B. Except that 1 part by mass of raw coal B and 2.5 parts by mass of potassium hydroxide (KOH) were mixed, put into a nickel reaction vessel, heated at 750 ° C. for 1 hour under nitrogen, and subjected to activation treatment. The same operation as in Example 1 was performed to obtain activated carbon for an electric double layer capacitor. Table 1 shows the specific surface area, residual potassium amount and true specific gravity of the activated carbon. Moreover, the electric double layer capacitor was produced by the same operation as Example 1 using the said activated carbon. Table 1 shows the capacitance of the electric double layer capacitor cell and the cycle characteristics (capacitance retention rate after repeated charging and discharging 1000 times).

<Comparative Example 1>
Only fluid catalytic cracking residual oil A obtained in Example 1 was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke, and then subjected to alkali activation treatment in the same manner as in Example 1 to obtain An electric double layer capacitor was fabricated using activated carbon. Table 1 shows the specific surface area of activated carbon, the amount of residual potassium, the true specific gravity, the capacitance of the electric double layer capacitor cell, and the cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles).

<Comparative example 2>
Only the vacuum distillation residue oil A obtained in Example 1 was subjected to heat treatment at 400 kPa and 500 ° C. for 40 hours to be coke, and then subjected to alkali activation treatment in the same manner as in Example 1 to obtain activated carbon An electric double layer capacitor was fabricated using Table 1 shows the specific surface area of activated carbon, the amount of residual potassium, the true specific gravity, the capacitance of the electric double layer capacitor cell, and the cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles).

  As apparent from Table 1, by using the raw material oil composition of the present invention obtained by mixing the vacuum distillation residue oil and the fluid catalytic cracking residue oil, the amount of potassium remaining in the obtained activated carbon is greatly reduced. As a result, the electrostatic capacity retention rate of the electric double layer capacitor using the same can be improved.

<Example 3>
The raw material oil composition C was prepared by mixing the vacuum distillation residual oil A and the fluid catalytic cracking residual oil A at a mass ratio of 1: 1. This raw material oil composition C was put in a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw carbon C was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.5% by mass.
Next, the produced raw coal C was fired at 1000 ° C. for 5 hours to obtain calcined coke (needle coke). Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
Further, 30% by mass of a coal-based binder pitch was added to calcined coke, and a cylindrical piece was produced with an extruder. This piece was fired at 1000 ° C. for 1 hour using a muffle heating furnace, and the thermal expansion coefficient after firing was measured. Furthermore, the piece was heat-treated from room temperature to 2800 ° C., and the degree of expansion in this process was measured as puffing. The obtained results are shown in Table 2.

<Example 4>
The raw material oil composition D was prepared by mixing the vacuum distillation residue oil A and the fluid catalytic cracking residue oil A at a mass ratio of 1: 5. This raw material oil composition D was put in a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw carbon D was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 2.5% by mass.
Next, the produced raw coal D was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.

<Example 5>
The raw material oil composition E was prepared by mixing the vacuum distillation residual oil A and the fluid catalytic cracking residual oil A at a mass ratio of 1: 3. This raw material oil composition E was put in a test tube and heat treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw coal E was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.0% by mass.
Next, the produced raw coal E was calcined at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.

<Comparative Example 3>
The vacuum distillation residue oil A was put into a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. Next, the produced raw coal was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.

<Comparative example 4>
The fluid catalytic cracking residual oil A was put into a test tube and heat treated at 400 kPa and 500 ° C. for 40 hours to be coke. Next, the produced raw coal was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.

<Comparative Example 5>
Low-sulfur crude oil with a sulfur content of 0.2% by mass, nitrogen content of 0.3% by mass and saturation content of 40% by mass is distilled under reduced pressure, initial boiling point 410 ° C., asphaltene content of 12% by mass, saturation content of 40% by mass, sulfur content A vacuum distillation residue oil (hereinafter referred to as “vacuum residue oil B”) having 0.2 mass% and nitrogen content of 0.3 mass% was obtained. This reduced-pressure residue oil B was put in a test tube and heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke. When the produced raw carbon was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 18%.
Next, the produced raw coal was fired at 1000 ° C. for 5 hours to obtain calcined coke. Table 2 shows the sulfur content, nitrogen content and bulk specific gravity of the obtained calcined coke.
A cylindrical piece was prepared in the same manner as in Example 3 except that this calcined coke was used, and the thermal expansion coefficient and puffing were measured. The results are shown in Table 2.

The present invention is a power storage for carbon material YoHara fuel oil composition as well as to the raw material coal. In particular, the present invention relates to a raw material oil composition and raw material charcoal that provide activated carbon that can easily remove residual alkali metals as activated carbon for electric double layer capacitor electrodes.

Recently, carbon materials have been widely used in a charge reservoir field. As such a carbon material for power storage, for example, activated carbon having a relatively large surface area is used for an electrode of an electric double layer capacitor, and coke having a relatively small surface area is used as a negative electrode of a lithium ion secondary battery. Yes. In particular, electric double layer capacitors are attracting attention as backup power supplies, auxiliary power supplies, etc., and development focusing on the performance of activated carbon as an electrode for electric double layer capacitors has been widely made. Electric double layer capacitors using activated carbon as a polarizable electrode are excellent in electrostatic capacity, so that demand for electric device electrode applications and the like is growing rapidly with the development of the electronics field. Recently, in addition to the miniaturization of conventional memory backup power supplies, development of large-capacity products that can be used for auxiliary power supplies such as motors has been carried out.
As a method for producing these activated carbons, the carbonaceous material is subjected to a gas activation treatment or a chemical activation treatment, for example, an alkali activation treatment using an alkali metal hydroxide as an activation aid, and then an alkali metal or heavy metal from the activation treatment product. In order to remove water, neutralization washing with a strong acid such as hydrochloric acid, nitric acid or sulfuric acid is generally performed.
With the demand for higher performance of electric double layer capacitors, there has been a need to further reduce the residual alkali metal in activated carbon for electric double layer capacitor electrodes. However, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2005-123462), even if the alkali metal can be removed up to a certain level by repeated washing with water and pickling, it is difficult to remove it further. . For this reason, an electric double layer capacitor using a carbon material after alkali activation has an initial capacitor capacity, but has a problem of deterioration over time such that the capacitor capacity greatly decreases when used for a long time.

On the other hand, from the viewpoint of the cleaning operation, the cleaning operation is as simple as possible, that is, it is desirable that the number of times of cleaning is as small as possible in terms of cost. In Patent Document 2 (International Publication No. 2004-011371 pamphlet), an easily activated graphitized carbonaceous material is subjected to an alkali activation treatment, and the obtained activation treatment product is used as hot water, carbonated water, hot hydrochloric acid, aqueous ammonia, hot hydrochloric acid. In addition, although it is described that activated carbon is obtained by washing in order of hot water, since the washing operation is complicated, development of activated carbon having a structure in which residual alkali metal is easily removed has been strongly desired.
JP 2005-123462 A International Publication No. 2004-011371 Pamphlet

The present inventors have extensively studied from the viewpoint of raw material oil that is a raw material of activated carbon, combined with specific raw material oils, coking them, and then activated carbon obtained by alkali activation of the resulting raw carbon is washed In some cases, it was found that the cleaning liquid can easily enter and exit, and as a result, the residual alkali content in the activated carbon can be reduced and the cleaning operation can be simplified.
Note that the "coking coal" in the present invention, a feedstock such as heavy oil and residual oil obtained by coking processes, refers to a carbide as a raw material for activated carbon.

That is, the present invention has an initial boiling point of 300 ° C. or more obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0.3% by mass or less. 10 to 80% by mass of the first heavy oil, the second heavy oil 90 to 20 having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less. The present invention relates to a raw material oil composition for activated carbon for activated carbon , characterized by comprising:
Moreover, this invention relates to the raw material coal obtained by carrying out the coking process of the said raw material oil composition at 300-800 kPa and 400-600 degreeC.
The present invention also relates to activated carbon obtained by activating the raw coal or the raw coal heat-treated product obtained by heat-treating the raw coal at 550 to 900 ° C. under normal pressure with an alkali metal hydroxide.
The present invention also relates to an electric double layer capacitor using the activated carbon as an electrode material.

  Activated carbon obtained by alkali activation of the raw coal obtained by coking the raw oil composition of the present invention obtained by mixing a specific heavy oil is easy for the cleaning solution to enter and exit, and as a result, even in the same cleaning operation Since the amount of the remaining alkali metal is reduced, the cycle characteristics of the electric double layer capacitor using it as an electrode material are improved. Moreover, since the washing operation is simplified, the activated carbon can be manufactured at a lower cost, and its industrial value is extremely large.

Hereinafter, the present invention will be described in detail.
The raw material composition for raw coal of the present invention is a raw material composition suitable for producing raw material coal for activated carbon, and is a heavy oil (hereinafter referred to as No. 1) having specific properties obtained by distillation under reduced pressure of petroleum. 1) and a heavy oil having a specific property obtained by fluid catalytic cracking of hydrocarbon oil (hereinafter referred to as a second heavy oil).

The first heavy oil according to the present invention has an initial boiling point of 300 ° C. or higher obtained as a residual oil when petroleum is distilled under reduced pressure, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0%. .3 heavy oil or less heavy oil.
Examples of petroleums that are raw oils of the first heavy oil include crude oil, atmospheric distillation residue obtained by distillation of crude oil, and mixed oils thereof.
The treatment conditions when the above raw material oil (petroleum) is distilled under reduced pressure are not particularly limited as long as the boiling point, asphaltene content, saturated content and sulfur content of the obtained first heavy oil satisfy the above conditions respectively. Is preferably 30 kPa or less, and the temperature is preferably 400 ° C. or more.
Among the heavy oils obtained as residual oils when distilled under reduced pressure in this way, the heavy oil satisfying the above-mentioned conditions for the boiling point, asphaltene content, saturated content and sulfur content is the first heavy oil according to the present invention. Used as
In other words, the first boiling point of the first heavy oil needs to be 300 ° C. or higher, and preferably 350 ° C. or higher. When the initial boiling point is less than 300 ° C., the yield of the raw coal is reduced, and the raw coal is in an amorphous structure, and the amount of residual alkali metal in the activated carbon obtained by alkali activation of the raw coal is large. It is not preferable. The upper limit of the initial boiling point is preferably 450 ° C. or lower, more preferably 400 ° C. or lower.

The asphaltene content of the first heavy oil needs to be 12% by mass or less, preferably 10% by mass or less, more preferably 9% by mass or less. When the asphaltene content exceeds 12% by mass, early coking proceeds, and the resulting raw coal has a coke structure with poor crystallinity, and the amount of residual alkali metal in the activated carbon obtained by activating the raw coal is increased. It is not preferable. The lower limit of the asphaltene content is 0% by mass.
Further, the saturated content of the first heavy oil needs to be 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more. If the saturated content is less than 50% by mass, the orientation of the mesophase is deteriorated, and the obtained raw coal has a coke structure with poor crystallinity, which is not preferable. The upper limit of the saturated content is preferably 85% by mass or less, and more preferably 80% by mass or less.
Further, the sulfur content of the first heavy oil needs to be 0.3% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less. If the sulfur content exceeds 0.3% by mass, there is a tendency to induce early coking, and the resulting raw coal has a coke structure with poor crystallinity, and the amount of residual alkali metal in the activated carbon obtained by alkali activation of the raw coal Increases and is not preferable.

The second heavy oil according to the present invention is a heavy oil having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less.
Here, “fluid catalytic cracking” means a process of cracking a high-boiling fraction using a solid acid catalyst or the like. The fluid catalytic cracker used for such treatment is FCC (Fluidized
Also called Catalytic Cracking equipment.
The hydrocarbon oil that is the raw material oil of the second heavy oil is not particularly limited as long as it can obtain a heavy oil whose initial boiling point and sulfur content satisfy the above conditions by fluid catalytic cracking, A hydrocarbon oil having a density at 15 ° C. of 0.8 g / cm ³ or more is preferred.
Such hydrocarbon oils include straight-run gas oil, vacuum gas oil, desulfurized gas oil, desulfurized vacuum gas oil, atmospheric distillation residual oil, vacuum distillation residual oil, shale oil, tar sand bitumen, orinocotal, coal liquefied oil, Examples include hydrorefined products and mixtures thereof. In the present invention, vacuum gas oil and desulfurized vacuum gas oil are particularly preferably used.
The conditions for fluid catalytic cracking are not particularly limited as long as it is possible to obtain a heavy oil whose initial boiling point and sulfur content satisfy the above conditions. For example, the reaction temperature is 480 to 550 ° C., the total pressure is 1 to 3 kg. / Cm ² G (98 to 294 kPa gauge pressure), catalyst / oil ratio of 1 to 20 wt / wt, and contact time of 1 to 10 seconds are preferable.
Examples of the catalyst used for fluid catalytic cracking include a silica / alumina catalyst, a zeolite catalyst, or a catalyst in which a metal such as platinum is supported on these catalysts. A commercial item may be used for these catalysts.

The initial boiling point of the second heavy oil thus obtained is required to be 150 ° C. or higher, preferably 200 ° C. or higher, more preferably 220 ° C. or higher. In addition, when the initial boiling point is less than 150 ° C., the yield of the raw coal decreases, and the obtained raw coal has an amorphous structure, and the remaining alkali metal in the activated carbon obtained by alkali activation of the raw coal The amount increases, which is not preferable. The upper limit of the initial boiling point is preferably 350 ° C. or lower, more preferably 300 ° C. or lower.
Further, the sulfur content of the second heavy oil needs to be 0.5% by mass or less, preferably 0.4% by mass or less, more preferably 0.3% by mass or less. If the sulfur content exceeds 0.5 mass%, there is a tendency to induce early coking, and the resulting raw coal has a coke structure with poor crystallinity, and the remaining alkali metal in the activated carbon obtained by alkali activation of the raw coal This is not preferable because the amount increases, and puffing of needle coke obtained by calcining the raw coal cannot be sufficiently suppressed.
The nitrogen content of the second heavy oil is not particularly limited, but is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and further preferably 0.1% by mass or less. .

The raw material oil composition of the present invention is obtained by mixing the first heavy oil and the second heavy oil described above.
As a mixing ratio of the first heavy oil and the second heavy oil, the content ratio of the first heavy oil is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and still more preferably. It mix | blends so that it may become 30-60 mass%.

Next, the raw material oil composition of the present invention is subjected to coking (carbonization) treatment.
Examples of the method for coking the raw material oil composition include a delayed coking method, a visbreaking method, a flexi coking method, a yurika process, and H-Oil. Among these, the delayed coking method is particularly preferable.
In the delayed coking method, the raw material oil composition is placed in a delayed coker and heat treated under pressure. The pressure of the delayed coker is preferably 300 to 800 kPa. The temperature is preferably 400 to 600 ° C, more preferably 450 to 550 ° C, and the time is preferably 24 to 72 hours, more preferably 36 to 60 hours.
By the coking process, carbide (raw coke) that becomes raw coal is obtained.

In the present invention, the raw material oil composition of the present invention containing the first heavy oil and the second heavy oil has a mosaic structure ratio of 10 μm or less of 5% or less when heat-treated at 500 ° C. It is desirable to provide raw coal that is preferably 2% or less. Here, a small proportion of a mosaic structure of 10 μm or less in the raw coal means that the growth state of liquid crystal called mesophase is good. The mesophase is an intermediate product produced by thermal decomposition and polycondensation accompanying heat treatment of the feedstock oil, and a series of aromatic rings developed along the same plane.
The method for measuring the mosaic structure in the raw coal is as described in “Basics of Carbonization Engineering”, Yuzo Sanada and Sugirou Otani (Ohm), page 147.
Conventionally, when a raw material oil contains a large amount of a saturated component, particularly an aliphatic component, a cross-linking reaction occurs in addition to the polymerization and polycondensation of aromatic components during coking. It is considered that the structure does not grow and the crystallinity is inferior, and as a result, the coefficient of thermal expansion of needle coke is considered to increase, and the amount of residual alkali metal in the activated carbon is considered to increase. In view of this point, it is a surprising result that even when the saturated content of the first heavy oil is 50% by mass or more, a coke having a mosaic structure of 10 μm or less and 5% or less can be obtained.

The raw coal obtained by the coking process can be converted into activated carbon by an alkali activation treatment. Moreover, in carrying out the alkali activation treatment, it is also preferably employed that the raw coal is heat treated at 550 to 900 ° C., preferably 600 to 850 ° C. under an inert atmosphere and normal pressure, and then subjected to the alkali activation treatment.
In the present invention, the activated carbon thus obtained is used as an electrode material for an electric double layer capacitor.
As a method for activating the raw coal or the raw material for heat treatment of raw material carbon, an activation furnace is used to heat the raw material coal or the raw material for heat treatment of raw material coal at 500 to 1200 ° C. together with a metal hydroxide in an atmosphere of nitrogen gas or inert gas. A method can be mentioned. Specific examples of the metal hydroxide include alkali metal hydroxides such as potassium hydroxide, sodium hydroxide and lithium hydroxide, and alkaline earth metal hydroxides such as magnesium hydroxide and barium hydroxide. be able to. Moreover, not only 1 type but 2 or more types can also be used in combination. Of these, potassium hydroxide is particularly preferable because it can efficiently form micropores.

The amount of the raw coal or raw material heat treated carbon and metal hydroxide can be 1 / 0.5 to 1/10 in the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide, Preferably it is 1/1 to 1/5.
By setting the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide to 1 / 0.5 or less, it is possible to sufficiently form micropores in the activated carbon and obtain activated carbon having a sufficient surface area. it can. Moreover, by making the mass ratio of raw coal or raw material heat treated carbon / metal hydroxide to 1/10 or more, the activation reaction can be efficiently performed without lowering the bulk density.
In addition, in the activation reaction, water or the like may coexist in addition to the raw coal or the raw material heat-treated with the raw coal and the metal hydroxide.

In the activation of the raw coal or the raw material for heat treatment of raw coal, the activation temperature may be, for example, in the range of 500 to 1200 ° C, preferably 600 to 1000 ° C, more preferably 600 to 800 ° C. Can do. When the activation temperature is in the above range, activated carbon having sufficient fine pores can be obtained efficiently. The activation treatment time can be appropriately selected in relation to conditions such as temperature, and can include 3 to 6 hours, for example.
Examples of the inert gas at the time of activation include inert gas and nitrogen gas. For example, it is preferable to supply such that the oxygen concentration in the activation atmosphere can be maintained at 100 ppm by volume or less.

The cleaning of the activated material is a cleaning in which the activated material is washed with a cleaning liquid to perform solid-liquid separation. The activated material is immersed in the cleaning liquid and mixed with the cleaning liquid by stirring and heating as necessary, and then the cleaning liquid is removed. The method of doing can be mentioned. As the cleaning liquid, water and an aqueous acid solution are preferably used. For example, cleaning with water, cleaning with an aqueous acid solution, and further cleaning with water can be used in appropriate combination. Preferred examples of the acid aqueous solution include hydrohalic acids such as hydrochloric acid, hydroiodic acid, and hydrobromic acid, and inorganic acids such as sulfuric acid and carbonic acid. Examples of the concentration of the acid aqueous solution include 0.01 to 3N. Cleaning with these cleaning liquids can be repeated a plurality of times as necessary.
After the final washing of the washing step using the washing liquid, solid-liquid separation is performed from the washing liquid, and heating, air drying, and the like are performed as appropriate to remove moisture and obtain dried activated carbon.

The activated carbon obtained by alkali activation of the raw coal obtained by coking the raw material oil composition of the present invention is characterized by less residual alkali metal when washed by the same washing operation compared to conventional activated carbon. Have. The reason why the residual alkali metal is reduced is that the raw coal according to the present invention has a crystal structure in which the metal hydroxide of the activator is easy to enter and escape, and the obtained activated carbon is infiltrated with the cleaning liquid and This is considered to be due to the crystal structure that facilitates escape.
In addition to this, when the activated carbon according to the present invention is used for an electrode of an electric double layer capacitor, it is easy for electrolyte ions to enter and exit during charge and discharge, and the capacitance retention rate in the cycle characteristic test is improved. .

The electric double layer capacitor of the present invention uses activated carbon obtained by activating the raw coal or raw material heat-treated from the raw oil composition of the present invention as an electrode material.
The electrode of the electric double layer capacitor of the present invention is not particularly limited as long as it contains the above activated carbon, but may contain a binder, a conductive agent, etc., and is integrated with the current collector. It may be what you did.
As the binder, known ones can be used, and specifically, fluorinations such as polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and fluoroolefin / vinyl ether copolymer cross-linked polymers. Examples thereof include polymers, celluloses such as carboxymethyl cellulose, vinyl polymers such as polyvinyl pyrrolidone and polyvinyl alcohol, and polyacrylic acid. Specifically, the content of the binder in the electrode material may be 0.1 to 30% by mass.
Specific examples of the conductive agent include powders such as carbon black, acetylene black, and powdered graphite. As content in the electrode material of a electrically conductive agent, the range of 1-50 mass% is preferable, More preferably, it is 2-30 mass%.
In order to produce an electrode using these materials, for example, a method of adding the activated carbon, the binder, and a conductive agent to a solvent that dissolves the binder and applying the slurry as a slurry to a sheet-like current collector, Examples thereof include a method in which the activated carbon, the binder, and the conductive agent are kneaded without using a solvent and pressure-molded at room temperature or under heating.
As the current collector, known materials and shapes can be used, and specific examples include metals such as aluminum, titanium, tantalum, and nickel, and alloys such as stainless steel.

  The electric double layer capacitor of the present invention can be produced as a unit cell which is provided with a pair of electrodes as a positive electrode and a negative electrode facing each other through a separator and immersed in an electrolytic solution. As the separator, unemployed cloth made of polypropylene fiber or glass fiber, cellulose paper, or the like can be used.

As the electrolytic solution, an aqueous electrolytic solution or a non-aqueous electrolytic solution can be used, but it is preferable to use a non-aqueous electrolytic solution. Examples of the non-aqueous electrolyte include those obtained by dissolving an electrolyte in an organic solvent. Specific examples of the solvent include propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, and 3-methylsulfolane. Such as sulfolane derivatives, 1,2-dimethoxyethane, etc., dimethoxyethane, acetonitrile, glutaronotolyl, valeronitrile, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, methyl formate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc. Can be used alone or in combination of two or more. Examples of the electrolyte of the electrolytic solution include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, and quaternary phosphonium salts. _{C 2 H 5) 4 NBF 4} , (C 2 H 5) 3 (CH 3) NBF 4, (C 2 H 5) 4 PBF 4, (C 2 H 5) 3 (CH 3) PBF 4 and the like Can do. The electrolyte concentration in the electrolytic solution can be 0.1 to 5 mol / L, and preferably 0.5 to 5 mol / L.

As the shape of the electric double layer capacitor of the present invention, for example, a coin type and a pair of electrodes in which a pair of electrodes of a sheet shape or a disk shape having a thickness of 50 to 500 μm are housed in a metal case via a separator. Examples thereof include a wound type wound through a separator, and a laminated type in which a pair of electrodes provided via a separator are provided in multiple layers.
In the electric double layer capacitor of the present invention, since the activated carbon is used as an electrode material, cycle characteristics are improved, and excellent durability and excellent capacity retention are exhibited.

  In the present invention, “sulfur content” means a value measured in accordance with JIS K2541 in the case of oil, and a value measured in accordance with JIS M 8813 in the case of coke. The “nitrogen content” means a value measured according to JIS K 2609 in the case of oil, and a value measured according to JIS M 8813 in the case of coke. Further, “saturated content” and “asphaltene content” mean values measured using a thin layer chromatograph.

Coking coal raw material oil composition of the present invention is used in the prime suitable as a activated carbon production for an electric double layer capacitor electrode.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.

<Example 1>
(1) Preparation of raw material oil composition First, an atmospheric distillation residual oil (density 0.92 g / cm ³ , sulfur content 0.35 mass%) was subjected to a heating furnace outlet temperature of 350 ° C. and a pressure of 1.3 kPa. Distilled under reduced pressure, with an initial boiling point of 410 ° C., an asphaltene content of 9% by mass, a saturation content of 61% by mass, a sulfur content of 0.1% by mass, and a nitrogen content of 0.3% by mass (hereinafter referred to as “vacuum distillation residue oil” A ”).
This vacuum distillation residue oil A was put into a test tube and heat-treated at normal pressure and 500 ° C. for 3 hours to be coke. When the produced coke was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 15% by mass.
Further, desulfurized vacuum gas oil (sulfur content: 500 mass ppm, density: 0.88 g / cm ^{3 at} 15 ° C.) is subjected to fluid catalytic cracking to obtain fluid catalytic cracking residual oil (hereinafter referred to as “fluid catalytic cracking residual oil A”). It was. The initial boiling point of the obtained fluid catalytic cracking residual oil A is 210 ° C., the sulfur content is 0.1% by mass, the nitrogen content is 0.1% by mass, the asphaltene content is 0% by mass, and the saturated content is 34% by mass. Met.
This fluid catalytic cracking residual oil A was put in a test tube and heat treated at normal pressure and 500 ° C. for 3 hours to be coke. When the produced coke was embedded in a commercially available resin and observed with a polarizing microscope, the presence of a mosaic structure of 10 μm or less was not recognized.

(2) Preparation of raw coal Next, vacuum distillation residual oil A and fluid catalytic cracking residual oil A were mixed at a mass ratio of 3: 7 to obtain raw oil composition A. This raw material oil composition A was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke to obtain coke (raw coal A). When the produced raw coal A was embedded in a commercially available resin and observed with a polarizing microscope, the mosaic structure of 10 μm or less was 3.5% by mass.

(3) Activation of coking coal 1 part by mass of coking coal A and 2.5 parts by mass of potassium hydroxide (KOH) are mixed, put in a nickel reaction vessel, heated at 750 ° C. for 1 hour under nitrogen, and activated. Processed.
After the activation treatment, the reaction mixture inside the reaction vessel was cooled to 300 ° C., and carbon dioxide was passed instead of nitrogen to deactivate the metal potassium. Thereafter, 20 kg of water was added to 2 kg of the reaction product, stirred at room temperature for 1 hour, and filtered under pressure. This operation was performed twice. Subsequently, 20 kg of 0.3N hydrochloric acid was added, stirred for 3 hours, and filtered under pressure. An additional 20 kg of water was added, and the mixture was stirred for 1 hour and filtered under pressure. This operation was also performed twice. The obtained solid was dried at 130 ° C. to obtain activated carbon for an electric double layer capacitor. Table 1 shows the specific surface area, residual potassium amount and true specific gravity of the activated carbon.

(4) Production of electric double layer capacitor Activated carbon (0.8 g) obtained above, Ketjen black (0.1 g), and polytetrafluoroethylene (0.1 g) were mixed in a mortar. This mixture was sandwiched between two 0.1 mm thick triacetate films and rolled by passing 20 times between nip rolls having a width of 160 mm, an upper and lower roll interval of 0.7 mm, and a pressure of 23.0 MPa. Two circles having a diameter of 16 mm were punched out from the rolled sheet to obtain carbon electrodes. The carbon electrode was dried in a vacuum dryer for 2 hours.
A cellulose separator having a thickness of 50 μm is sandwiched between two electrodes impregnated with an electrolytic solution (one mole of (C ₂ H ₅ ) ₃ (CH ₃ ) NBF ₄ dissolved in 1 liter of propylene carbonate) It was enclosed in a SUS316 coin cell having a diameter of 20 mm. In this case, a current collector carbon coating applied to the surface of a 20 μm thick aluminum foil was used as a current collector, and the paint side was sandwiched between the carbon electrode and the cell so as to face the carbon electrode.
Table 1 shows the capacitance and cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles) of the electric double layer capacitor cell thus fabricated.

<Example 2>
The vacuum distillation residue oil A and the fluid catalytic cracking residue oil A were mixed at a mass ratio of 6: 4 to obtain a raw material oil composition B. This raw material oil composition B was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke to obtain raw coal B. Except that 1 part by mass of raw coal B and 2.5 parts by mass of potassium hydroxide (KOH) were mixed, put into a nickel reaction vessel, heated at 750 ° C. for 1 hour under nitrogen, and subjected to activation treatment. The same operation as in Example 1 was performed to obtain activated carbon for an electric double layer capacitor. Table 1 shows the specific surface area, residual potassium amount and true specific gravity of the activated carbon. Moreover, the electric double layer capacitor was produced by the same operation as Example 1 using the said activated carbon. Table 1 shows the capacitance of the electric double layer capacitor cell and the cycle characteristics (capacitance retention rate after repeated charging and discharging 1000 times).

<Comparative Example 1>
Only fluid catalytic cracking residual oil A obtained in Example 1 was heat-treated at 400 kPa and 500 ° C. for 40 hours to be coke, and then subjected to alkali activation treatment in the same manner as in Example 1 to obtain An electric double layer capacitor was fabricated using activated carbon. Table 1 shows the specific surface area of activated carbon, the amount of residual potassium, the true specific gravity, the capacitance of the electric double layer capacitor cell, and the cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles).

<Comparative example 2>
Only the vacuum distillation residue oil A obtained in Example 1 was subjected to heat treatment at 400 kPa and 500 ° C. for 40 hours to be coke, and then subjected to alkali activation treatment in the same manner as in Example 1 to obtain activated carbon An electric double layer capacitor was fabricated using Table 1 shows the specific surface area of activated carbon, the amount of residual potassium, the true specific gravity, the capacitance of the electric double layer capacitor cell, and the cycle characteristics (capacitance retention rate after 1000 charge / discharge cycles).

  As apparent from Table 1, by using the raw material oil composition of the present invention obtained by mixing the vacuum distillation residue oil and the fluid catalytic cracking residue oil, the amount of potassium remaining in the obtained activated carbon is greatly reduced. As a result, the electrostatic capacity retention rate of the electric double layer capacitor using the same can be improved.

Claims (9)

A first heavy oil having an initial boiling point of 300 ° C. or higher, an asphaltene content of 12% by mass or less, a saturation content of 50% by mass or more, and a sulfur content of 0.3% by mass or less obtained as a residual oil when petroleum is distilled under reduced pressure. And a second heavy oil having an initial boiling point of 150 ° C. or higher obtained by fluid catalytic cracking of hydrocarbon oil and a sulfur content of 0.5% by mass or less. Composition. The feed oil composition according to claim 1, wherein the petroleum is crude oil, atmospheric distillation residue obtained by distillation of crude oil, or a mixed oil thereof. The hydrocarbon oil is atmospheric distillation residue, vacuum distillation residue, shale oil, tar sand bitumen, orinocotal, coal liquefied oil, heavy oil obtained by hydrorefining these, straight-run gas oil, vacuum gas oil, desulfurized gas oil The feed oil composition according to claim 1, which is a desulfurized vacuum gas oil. The raw material oil composition according to claim 1, wherein the raw material oil composition gives a raw coal having a mosaic structure of 10 µm or less of 5% or less when heat-treated at 500 ° C. Coking coal obtained by coking the raw material oil composition according to any one of claims 1 to 4 at 300 to 800 kPa and 400 to 600 ° C. 6. Activated carbon obtained by activating the raw material charcoal according to claim 5 or a raw material heat-treated material obtained by heat-treating the raw material coal at 550 to 900 ° C. under normal pressure with an alkali metal hydroxide. An electric double layer capacitor using the activated carbon according to claim 6 as an electrode material. Needle coke obtained by calcining the raw coal according to claim 5 at 800 to 1600 ° C. The needle coke according to claim 8, wherein the sulfur content is 0.5 mass% or less and the nitrogen content is 0.1 mass% or less.