JP5777449B2 - Nitrogen-containing carbon material, method for producing the same, and electrode for fuel cell - Google Patents

Description

  The present invention relates to a nitrogen-containing carbon material, a method for producing the same, and a fuel cell electrode.

  Conventionally, carbon materials have been mainly used as adsorbents, etc., but they have basic properties such as physical properties of electronic materials such as conductivity, high thermal conductivity, low thermal expansion coefficient, lightness, and heat resistance. A wide range of applications has been studied. In particular, the chemical function has recently attracted attention and has been studied in the fields of a negative electrode for a lithium ion secondary battery, an electrode for a capacitor, an electrode for a polymer electrolyte fuel cell, a catalyst for a chemical reaction, and the like.

  Such a carbon material has been conventionally produced by carbonization using coconut shell, coal coke, coal or petroleum pitch, furan resin, phenol resin, or the like as a raw material.

  In recent years, attempts have been made to further expand the range of physical properties of carbon materials by incorporating other elements into such carbon materials. Under these circumstances, a carbon material doped with nitrogen atoms (hereinafter referred to as “nitrogen-containing carbon material”) has recently been used to develop oxygen reduction activity, so that an electrode for a polymer electrolyte fuel cell, a catalyst for a chemical reaction, etc. (See, for example, Patent Document 1).

International Publication No. 2008/123380

  However, in the conventional nitrogen-containing carbon material, the oxygen reduction activity in the electrode reaction is insufficient. Therefore, the present invention has been made in view of the above circumstances, and a nitrogen-containing carbon material having a high oxygen reduction activity in an electrode reaction, a method for producing the same, and an electrode for a fuel cell are compared with conventional nitrogen-containing carbon materials. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have performed a predetermined treatment in a step of carbonizing a precursor (a precursor of a nitrogen-containing carbon material) containing azulmic acid and a transition metal. The nitrogen-containing carbon material finally obtained has been found to exhibit high oxygen reduction activity as compared with conventional nitrogen-containing carbon materials in applications such as fuel cell electrodes, and has led to the present invention.

That is, the present invention is as follows.
[1] A step of carbonizing a precursor of a nitrogen-containing carbon material containing azulmic acid and iron, wherein the step includes a first step of performing a first heat treatment on the precursor, and a step of performing the first heat treatment. a second step of removing at least a portion of the iron from the precursor that is, have a, and a third step of performing a second heat treatment to the precursor at least partially removing the iron, the In the third step, the method for producing a nitrogen-containing carbon material , wherein the atmosphere around the precursor is an ammonia-containing gas atmosphere .
[2] The manufacturing method according to [1], further including a fourth step of pulverizing the precursor between the first step and the third step.
[3] The manufacturing method according to [1] or [2], wherein in the first step, the atmosphere around the precursor is an inert gas atmosphere.
[4] In the third step, the ammonia-containing gas atmosphere of pure ammonia gas, or pure ammonia gas What ammonia-containing gas atmosphere der diluted with an inert gas, the precursor around the gas in circulation are the method according to any one of [1] to [3].

  According to the present invention, it is possible to provide a nitrogen-containing carbon material having a high oxygen reduction activity in an electrode reaction, a method for producing the same, and a fuel cell electrode as compared with conventional nitrogen-containing carbon materials.

It is process drawing for demonstrating an example of the manufacturing method of the nitrogen containing carbon material which concerns on this invention.

  Hereinafter, a form for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary.

  FIG. 1 is a process diagram for explaining a method for producing a nitrogen-containing carbon material of the present embodiment. As shown in FIG. 1, the manufacturing method of the nitrogen-containing carbon material of this embodiment has process S14 which carbonizes the precursor of nitrogen-containing carbon material. Furthermore, in the method for producing a nitrogen-containing carbon material of the present embodiment, prior to step S14, step S10 for producing azulmic acid by polymerizing a raw material containing hydrocyanic acid, and step S12 for producing a precursor containing azulmic acid and a transition metal. And have. In the present specification, “azurmic acid” means a general term for polymers obtained by polymerizing hydrocyanic acid (hydrogen cyanide). Hereinafter, each process is explained in full detail.

  First, in step S10, a raw material mainly containing hydrocyanic acid is polymerized to obtain azulmic acid. The cyanic acid used in step S10 is not particularly limited, and those produced by a known method can be used. For example, hydrocyanic acid is by-produced in a method for producing acrylonitrile or methacrylonitrile by a gas phase catalytic reaction in which propylene, isobutylene, tert-butyl alcohol, propane or isobutane is reacted with ammonia or an oxygen-containing gas in the presence of a catalyst. For this reason, the hydrocyanic acid used by process S10 can be obtained very cheaply. Since the above-mentioned gas phase contact reaction is a conventionally known reaction, the reaction condition may be any known one. However, in order to increase the production of by-product hydrocyanic acid, it is also possible to supply a raw material that produces hydrocyanic acid by an ammoxidation reaction, such as methanol, to a reactor for synthesizing acrylonitrile or methacrylonitrile.

  Further, hydrocyanic acid produced by the Andrewsso method in which methane, which is the main component of natural gas, is reacted with ammonia and an oxygen-containing gas in the presence of a catalyst can also be used. Since this production method also uses methane as a raw material, it is a method by which hydrocyanic acid can be obtained at a very low cost.

  Of course, the method for producing hydrocyanic acid may be a laboratory production method using soda hydride or the like. However, the use of the above industrially produced hydrocyanic acid enables the production of hydrocyanic acid in large quantities and at low cost. To preferred.

  In step S10, a raw material mainly containing hydrocyanic acid is polymerized to obtain azulmic acid which is a black to brown polymer. Here, from the viewpoint of obtaining high-purity azulmic acid, the abundance ratio of the polymerizable substance other than hydrocyanic acid is preferably 40% by mass or less, more preferably 10% by mass with respect to the total amount of raw materials mainly containing hydrocyanic acid. % Or less, more preferably 5% by mass or less, and particularly preferably 1% by mass or less. In other words, the abundance ratio of hydrocyanic acid in the polymerizable material in the raw material is preferably 60% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and 99% by mass or more. Is particularly preferred.

  Azulmic acid can be produced by polymerizing hydrocyanic acid and optionally a small amount of other polymerizable substances in various ways. As a polymerization method, for example, a method of heating liquefied hydrocyanic acid or an aqueous solution of hydrocyanic acid, a method of leaving them for a long time, a method of adding a base to them, a method of irradiating them with light, a method of emitting high energy to them , Methods of performing various discharges in the presence thereof, and methods of electrolysis of an aqueous potassium cyanide solution. In addition, for example, Angew. Chem. 72, 379-384 (1960) and references cited therein, and known methods described in Vacuum Science, Volume 16, 64-72 (1969) and references cited therein.

In the method of adding a base to liquefied hydrocyanic acid or aqueous hydrocyanic acid and polymerizing hydrocyanic acid in the presence of the base, examples of the base include sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, organic base, ammonia. Ammonia water is exemplified. Examples of the organic base include primary amine (R ¹ NH ₂ ), secondary amine (R ¹ R ² NH), tertiary amine (R ¹ R ² R ³ N), and quaternary ammonium salt (R ¹ R ² R). ³ R ⁴ N ⁺ ). Here, R < ¹ >, R < ² >, R < ³ >, and R < ⁴ > show the C1-10 alkyl group, phenyl group, cyclohexyl group, and these groups obtained by combining these, which may be the same or different from each other. R ¹ , R ² , R ³ and R ⁴ may further have a substituent. Of these organic bases, aliphatic or cycloaliphatic tertiary amines are preferred. Examples of such tertiary amine include trimethylamine, triethylamine, tripropylamine, tributylamine, dicyclohexylmethylamine, tetramethylammonium hydroxide, N-methylpyrrolidine, 1,8-diazabicyclo [5.4.0]. Undec-7-ene (DBU). The said base is used individually by 1 type or in combination of 2 or more types.

  Among the polymerization methods of cyanic acid, from the viewpoint of not containing a metal component in the polymerization stage, it is preferable to heat liquefied hydrocyanic acid or aqueous hydrocyanic acid, leave them for a long time, irradiate them with light, Radiation is a method of polymerizing them in the presence of ammonia or an organic base.

  Further, in the purification process of cyanic acid by-produced in the ammoxidation process of propylene or the like, deposits may be generated in the purifier, and this deposit often contains a high proportion of azulmic acid. It is also possible to use azulmic acid recovered from this deposit.

  Since azulmic acid is a polymer of hydrocyanic acid, the ratio of (molar fraction of carbon) :( molar fraction of nitrogen) :( molar fraction of hydrogen) is ideally 1: 1: 1. However, depending on the production method, for example, since the added base is incorporated into the polymer chain or partially hydrolyzed in the aqueous solution, the composition depends on the polymerization conditions. And may be different. From the viewpoint of increasing the nitrogen residual ratio after carbonization of the nitrogen-containing carbon material, (molar fraction of nitrogen element) / (molar fraction of carbon element) in azulmic acid is preferably 0.2 to 1.2, more preferably. Is 0.3 to 1.1, particularly preferably 0.4 to 1.0. Further, from the viewpoint of increasing the carbonization yield, (molar fraction of hydrogen element) / (molar fraction of carbon element) is preferably 0.2 to 2.0, more preferably 0.5 to 1.5. Yes, particularly preferably 0.7 to 1.2. As a method for adjusting the mole fraction of each element, for example, when polymerization is performed under anhydrous conditions, deammonification due to hydrolysis is suppressed, and (mol fraction of nitrogen element) / (mol fraction of carbon element), (hydrogen (Mole fraction of element) / (Mole fraction of carbon element) increases. In addition, in the polymerization method using a base, since a part of the added base is taken into azulmic acid, the molar fraction of each element in the generated azurmic acid can be finely adjusted by changing the base used. The composition of azulmic acid can be measured using a CHN analyzer.

  Next, in step S12, a precursor containing azulmic acid and a transition metal, that is, a precursor of a nitrogen-containing carbon material is manufactured. A method for producing the precursor is not particularly limited, but a method in which the precursor is produced by mixing azulmic acid and the raw material of the transition metal in a solvent and then removing the solvent from the mixture is preferable. When azulmic acid and the transition metal raw material are mixed in a solvent, a part or all of azulmic acid may or may not be dissolved.

  Transition metals include Ti (titanium), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), and Cu (copper) from the viewpoint of carbonization promotion effect. ), Y (yttrium), Zr (zirconium), Nb (niobium), Mo (molybdenum), Tc (technetium), Ru (ruthenium), Rh (rhodium), Pd (palladium), Ag (silver), Ta (tantalum) ), W (tungsten), Re (rhenium), Ir (iridium), Pt (platinum), Au (gold) and lanthanoid elements. More preferred are Fe, Co, Ni, Pd, Pt, Au, La and Ce, further preferred are Pt, Fe, Co and Ni, particularly preferred are Fe and Co, and most preferred is Fe. . These transition metals can be contained in the precursor alone or in combination of two or more.

  The raw material of the transition metal is not particularly limited, and examples thereof include transition metal complexes, inorganic acid salts, organic acid salts, and other transition metal compounds, and more specifically, for example, transition metal oxalate salts. , Hydroxides, oxides, nitrites, nitrates, acetates, ammonium salts, carbonates, chlorides, bromides, alkoxides, acetylacetonates, phthalocyanines and porphyrins.

  Examples of the raw material when the transition metal is iron include iron complexes, iron inorganic acid salts, iron organic acid salts, and other iron compounds. More specifically, for example, iron (II) Phthalocyanine, iron (III) acetylacetonate, iron (II) methoxide, iron (III) ethoxide, iron (III) isopropoxide, bis (cyclopentadienyl) iron, bis (methylcyclopentadienyl) iron, bis (Ethylcyclopentadienyl) iron, bis (isopropylcyclopentadienyl) iron, bis (tetramethylcyclopentadienyl) iron, ferric chloride, ferric citrate, ferric phosphide, tartaric acid Iron, ferrous fumarate, ammonium hexacyanoferrate (II), ammonium hexacyanoferrate (II) ammonium iron (III), ammonium iron oxalate (III) Japanese products, ammonium iron (III) sulfate, iron (III) ammonium sulfate, bis (cyclopentadienyl) iron, ferric chloride, iron ethylenediaminetetraacetate, ammonium iron citrate, ferric nitrate, iron (II) acetate And iron (II) fumarate, iron (II) gluconate, iron oxalate and iron (III) hydroxide. Among these, from the viewpoint of obtaining a nitrogen-containing carbon material having better oxygen reduction activity in the electrode reaction, iron complexes and iron inorganic acid salts are preferable, and iron (II) phthalocyanine and iron nitrate are more preferable. The raw materials for iron are used singly or in combination of two or more.

  Examples of the raw material when the transition metal is nickel include nickel complexes, nickel inorganic acid salts, nickel organic acid salts, and other nickel compounds. More specifically, for example, nickel (II) Phthalocyanine, nickel (II) trifluoroacetylacetonate, bis (cyclopentadienyl) nickel, bis (isopropylcyclopentadienyl) nickel, bis (pentamethylcyclopentadienyl) nickel, bis (tetramethylcyclopentadienyl) ) Nickel, nickel borate, nickel hydroxyacetate, nickel naphthenate, bis (ethylcyclopentadienyl) nickel, nickel (II) ammonium sulfate, bis (1,5-cyclooctadiene) nickel, bis (tetramethylcyclopenta) Dienyl) , Hexaamminenickel (II) bromide, nickel (II) chloride, nickel (II) acetate tetrahydrate, nickel (II) acetylacetonate, nickel ammonium sulfate, nickel (II) chloride, nickel bromide, Nickel (II) carbonate, nickel (II) formate, nickel (II) hexafluoroacetylacetonate, nickel (II) oxide, nickel (II) hydroxyacetate, nickel (II) lactate, nickel (II) naphthenate, nickel nitrate And nickel (II) oxalate, nickel (II) 2,4-pentandionate, nickel sulfate, nickel amidosulfate and nickel hydroxide. Among these, from the viewpoint of obtaining a nitrogen-containing carbon material having better oxygen reduction activity in the electrode reaction, a nickel complex and an inorganic acid salt of nickel are preferable, and nickel (II) phthalocyanine and nickel nitrate are more preferable. The nickel raw materials may be used alone or in combination of two or more.

  Examples of the raw material when the transition metal is cobalt include a cobalt complex, a cobalt inorganic acid salt, a cobalt organic acid salt, and other cobalt compounds, and more specifically, for example, cobalt (II). Phthalocyanine, cobalt (II) trifluoroacetylacetonate, bis (cyclopentadienyl) cobalt, bis (isopropylcyclopentadienyl) cobalt, bis (pentamethylcyclopentadienyl) cobalt, bis (tetramethylcyclopentadienyl) ) Cobalt, cobalt borate, cobalt hydroxyacetate, cobalt naphthenate, bis (ethylcyclopentadienyl) cobalt, cobalt (II) ammonium sulfate, bis (1,5-cyclooctadiene) cobalt, bis (tetramethylcyclopenta) Dienyl) Hexaamminecobalt (II) bromide, hexaamminecobalt (II) chloride, cobalt (II) acetate tetrahydrate, cobalt (II) acetylacetonate, cobalt ammonium sulfate, cobalt (II) chloride, cobalt bromide, Cobalt carbonate (II), cobalt formate (II), hexafluoroacetylacetonato cobalt (II), cobalt oxide (II), cobalt cobalt hydroxide (II), cobalt lactate (II), cobalt nitrate, cobalt oxalate (II) , 2,4-pentanedioic acid cobalt (II), cobalt sulfate, amido cobalt sulfate, and cobalt hydroxide. Among these, from the viewpoint of obtaining a nitrogen-containing carbon material having better oxygen reduction activity in the electrode reaction, a cobalt complex and an inorganic acid salt of cobalt are preferable, and cobalt (II) phthalocyanine and cobalt nitrate are more preferable. More preferred is cobalt nitrate. Cobalt raw materials are used singly or in combination of two or more.

  Examples of the raw material when the transition metal is platinum include platinum complexes, platinum compounds having a halogen atom, and other platinum compounds. More specifically, for example, platinum (II) acetylacetonate, hexabromo Ammonium platinate (IV), ammonium hexachloroplatinate (IV), ammonium tetrachloroplatinate (II), bis (acetylacetonate) platinum (II), bis (ethylenediamine) platinum (II) chloride, chloroplatinic acid hexahydrate Japanese chloroplatinic acid hexahydrate, dichlorodiammine platinum (II), tetrachlorodiammine platinum (IV), 1,1-cyclobutanedicarboxylatodiammine platinum (II), diammine dichloroplatinum (II), diammonium nitrite Platinum (II), dichlorobis (benzonitrile) platinum (II , Hexachloroplatinic acid (IV) dihydrogen, hexabromoplatinic acid (IV) dihydrogen, hexahydrooxoplatinic acid (IV), diphenyl (1,5-cyclooctadiene) platinum (II), hexahydroxoplatinum (IV) acid Platinum (II) bromide, platinum (II) chloride, platinum (II) hexafluoroacetylacetonate, tetraammineplatinum (II) chloride, tetraammineplatinum bicarbonate (II), tetraammineplatinum (II) hydroxide, tetraamineplatinum nitrate Examples thereof include (II), tetraamineplatinum (II) tetrachloroplatinum (II) acid and hexahydroxoplatinum nitrate aqueous solution. Platinum materials may be used alone or in combination of two or more.

  As the solvent, a solvent having high affinity with azulmic acid is preferable. Examples of such a solvent include an organic solvent and water, and a solution in which a solute other than azulmic acid is dissolved in these solvents, for example, a basic aqueous solution or an acidic aqueous solution may be used. Among these, polar solvents tend to have higher affinity with azulmic acid. A solvent is used individually by 1 type or in combination of 2 or more types.

  As the organic solvent, a polar solvent is preferable. Polar solvents include chloroform, ethyl acetate, tetrahydrofuran, methylene chloride, acetone, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, acetic acid, 1-butanol, 2-propanol, 1-propanol, ethanol, methanol, formic acid and amino Examples thereof include a solvent having a group. A primary amine can be illustrated as a solvent which has an amino group. Specifically, as a solvent having an amino group, ammonia; methylamine, ethylamine, propylamine, isopropylamine, butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, triethylamine Monoamines such as decylamine, tetradecylamine, pentadecylamine, cetylamine, cyclopropylamine, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, aniline, toluidine, benzylamine, naphthylamine, allylamine; ethylenediamine, trimethylenediamine, Tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-dia Diamines such as nooctane, 1,9-diaminononane, 1,10-diaminodecane, phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethyleneexamine; and 1,2,3-triaminopropane, tri Examples include triamines such as aminobenzene, triaminophenol and melamine.

  Among these, as the solvent having an amino group, ethylenediamine, trimethylenediamine, tetramethylenediamine, and 1,2,3-triaminopropane are preferable, and ethylenediamine is more preferable.

  Examples of the basic aqueous solution include an aqueous solution of a primary amine, an aqueous solution of an alkali metal, an aqueous solution of an alkaline earth metal, and an aqueous solution of a quaternary ammonium salt. Examples of the primary amine aqueous solution include ammonia aqueous solution, methylamine aqueous solution, ethylamine aqueous solution, propylamine aqueous solution, isopropylamine aqueous solution, butylamine aqueous solution, amylamine aqueous solution, hexylamine aqueous solution and the like; ethylenediamine aqueous solution, trimethylenediamine aqueous solution, Examples include diamine aqueous solutions such as tetramethylene diamine aqueous solutions; and triamine aqueous solutions such as melamine aqueous solutions. Examples of the alkali metal aqueous solution include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution. Examples of the alkaline earth metal aqueous solution include a calcium hydroxide aqueous solution and a barium hydroxide aqueous solution. Examples thereof include tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrapropylammonium hydroxide aqueous solution and tetrabutylammonium hydroxide aqueous solution. Among these, preferable basic aqueous solutions are ammonia aqueous solution, ethylenediamine aqueous solution, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution and tetraethylammonium hydroxide aqueous solution, and more preferably ethylenediamine aqueous solution.

  Examples of the acidic aqueous solution include a sulfuric acid aqueous solution, a nitric acid aqueous solution, a hydrochloric acid aqueous solution, and a phosphoric acid aqueous solution. Among these, a sulfuric acid aqueous solution is preferable.

  The mixing ratio of the azurmic acid and the transition metal raw material is not particularly limited, but the mass ratio of the transition metal raw material to the azulmic acid is preferably 0.001 to 10, more preferably 0.005 to 1. Preferably, it is 0.01-1 more preferably. When the transition metal mass ratio is 0.001 or more, the precursor tends to be more sufficiently carbonized. When the transition metal mass ratio is 10 or less, the transition metal is used for removing the transition metal after carbonization. There is a tendency to reduce the amount of acid.

  Prior to adding azulmic acid to the solvent, it is preferable to grind azulmic acid in advance with a ball mill or the like from the viewpoint of ease of mixing.

  What is necessary is just to determine the ratio of an azurmic acid and a solvent according to solubility, the ratio to dilute, and a mixing method. For example, the amount of the solvent is preferably 1 to 10,000 times, more preferably 10 to 100 times, by mass ratio with respect to the amount of azulmic acid. By setting the mass ratio to 1 or more, the solubility of azulmic acid in the solvent tends to be improved. By setting the mass ratio to 10,000 or less, energy consumed when removing the solvent can be suppressed. There is a tendency.

  Although it may react with azulmic acid depending on the type of solvent, it may be reacted as long as it is in a dissolved state as a whole. That is, in a liquid obtained by mixing azurmic acid and a transition metal raw material in a solvent (a part or all of azulmic acid may be dissolved or not dissolved), A method for producing a nitrogen-containing carbon material via a mode including a form in which at least a part of a solvent is reacted is also in the category of this embodiment. In step S10, azurmic acid can also be obtained by polymerizing hydrocyanic acid in a solvent such as water, but a liquid (azurmine) containing azurmic acid generated in the solvent used at this time as it is. The acid may be partly or wholly dissolved or not dissolved in the precursor). That is, the transition metal raw material may be added to and mixed with the liquid in a state in which the azulmic acid generated in the solvent is contained as it is. The produced azulmic acid is often poorly soluble in a solvent, but it can also be dissolved by adding an acid and / or base thereto.

  Although the solvent temperature at the time of mixing an azurmic acid and a transition metal in a solvent is not specifically limited, It is preferable that it is more than the melting | fusing point of a solvent, and below the boiling point or decomposition temperature of a solvent. Examples of the mixing time include 1 minute to 100 hours. The mixing time is preferably 10 minutes to 20 hours, more preferably 30 minutes to 2 hours. During mixing, it is preferable to shake, stir or apply ultrasonic waves.

  As a method for removing a solvent from a mixture obtained by mixing azulmic acid and a transition metal raw material in a solvent, a method for removing the solvent by volatilizing the solvent by heating the mixture under normal pressure or reduced pressure, and a mixture Can be exemplified by a method of removing the solvent by spray drying.

  Thus, a precursor (a precursor of a nitrogen-containing carbon raw material) is obtained.

  Next, in step S14, the precursor is carbonized. In step S14, the precursor is carbonized by applying heat treatment to the precursor a plurality of times to synthesize a nitrogen-containing carbon material. At this time, at least a part of the transition metal is removed from the precursor between the heat treatments (hereinafter also referred to as “interval between heat treatments”) (hereinafter, this treatment is also simply referred to as “removal treatment”). Further, the transition metal may be further removed after the final heat treatment. Here, “carbonization” means that the content ratio of the carbon element to the total of the nitrogen element, hydrogen element, and carbon element contained in the finally obtained nitrogen-containing carbon material is the nitrogen element and hydrogen element contained in the precursor. This means a treatment that is higher than the carbon element content relative to the total carbon element.

  Each time heat treatment is repeated, it is considered that a nitrogen-containing carbon material is partially generated in the precursor. Therefore, after the heat treatment is performed once or more, chemically, the “precursor” and the “nitrogen-containing carbon material” It becomes an intermediate state. However, in the present invention, for the sake of convenience, such an intermediate state is also referred to as a “precursor”.

  In the removal treatment, as a method of removing at least a part of the transition metal, a method of bringing the precursor into contact with a solvent is preferable. Examples of the solvent used for this include acids typified by sulfuric acid, nitric acid, hydrogen chloride and phosphoric acid, and aqueous solutions of those acids. Among these, an aqueous solution is preferable from the viewpoint of handling. When contacting the precursor using an aqueous acid solution as the solvent, the pH of the solvent is preferably 4 or less, more preferably 3 or less, from the viewpoint of more efficiently removing the transition metal. It is particularly preferred. What is necessary is just to adjust the acid concentration in the aqueous solution of acid so that it may become such pH. The temperature of the acid or the aqueous acid solution is not particularly limited, but it is preferably 0 to 100 ° C., and preferably 10 to 50 ° C. from the viewpoint of efficiently removing the acid or the aqueous acid solution in a stable state. It is more preferable. Examples of the method of bringing the precursor into contact with the solvent include a method of immersing the precursor in the solvent and a method of spraying (spraying) the solvent onto the precursor. When the precursor is immersed in the solvent, it is preferable to rock the precursor and / or the solvent by stirring or the like so as to wash the precursor because the transition metal removal efficiency is further improved.

  Prior to the removal treatment, the efficiency of removing the transition metal can be further increased by pulverizing the precursor (hereinafter also simply referred to as “pulverization treatment”). In this case, from the viewpoint of increasing the efficiency of removing the transition metal, it is pulverized until the average particle diameter of the precursor (volume-based median diameter: 50% D) becomes 0.001 to 100 μm, and classified as necessary. preferable. In order to grind to this extent, dry and wet ball mills, bead mills, jet mills, hammer mills and the like can be used. However, since the precursor before heat treatment is soft and difficult to grind, it is preferable to grind the precursor that has been heat-treated at least once. In addition, if the nitrogen-containing carbon material after the completion of all the heat treatments is pulverized, a new surface may be exposed due to the pulverization, so that the physical properties of the nitrogen-containing carbon material may become uneven. It is preferable to carry out. The classification can be performed by a known method used for carbon materials and nitrogen-containing carbon materials.

  If the precursor is heat-treated at least three times, it is possible to perform the removal treatment between all heat treatments, but the removal treatment may be performed between any heat treatments, and removal is performed between all heat treatments. There is no need to do any processing. For example, (1) the pulverization treatment may be performed after the first heat treatment, the removal treatment may be performed after the second heat treatment, and then the third heat treatment may be performed, or (2) the pulverization treatment may be performed after the first heat treatment. After performing the removal process in this order, a second heat treatment may be performed. Further, since the removal process may be repeated a plurality of times, it is not always necessary to remove all the transition metals from the precursor by a single removal process.

  More specifically, when the heat treatment is performed twice and the removal treatment is performed between the heat treatments, the pulverization treatment is performed between the first heat treatment and the removal treatment, between the first heat treatment and the removal treatment, before the first heat treatment. It can be carried out in any one or more stages during the heat treatment and after the second heat treatment.

  In addition, when the heat treatment is performed twice and the removal treatment is performed between the heat treatment and after the second heat treatment, the pulverization treatment is performed between the first heat treatment and the first removal treatment before the first heat treatment. Can be performed in one or more stages between the first removal treatment and the second heat treatment, between the second heat treatment and the second removal treatment, and after the second removal treatment. It is.

  Further, when the heat treatment is performed three times, the removal treatment is performed at any one or more stages between the first heat treatment and the second heat treatment, and between the second heat treatment and the third heat treatment. In addition, it may be performed after the third heat treatment. In this case, the pulverization process can be performed between any of the heat treatments and the removal process, or between the heat treatments where the removal process is not performed, and can be performed after the last heat treatment or the removal process.

  It is considered that the transition metal in which the valence has been changed by the heat treatment is removed by performing the removal treatment after performing the heat treatment at least once. For example, when the transition metal contained in the precursor is iron, since the transition metal source is usually a salt, iron exists in a divalent or trivalent state in the precursor before heat treatment. When this precursor is subjected to heat treatment, some of the iron is reduced to zero valence, but the present inventors assume that this reduced iron affects the subsequent heat treatment. When the heat treatment is further advanced in the presence of a transition metal in a reduced state, not limited to iron, the transition metal acts on nitrogen in the precursor, or the ratio of nitrogen contained in the resulting nitrogen-containing carbon material decreases. There was a tendency to end up. Therefore, substances that affect the reaction during the heat treatment (transition metals or substances derived from them) are synthesized by performing the heat treatment stepwise and synthesizing the nitrogen-containing carbon material while removing the generated transition metal in the reduced state between the heat treatments. ) Is excluded from the precursor, and it is possible to obtain a nitrogen-containing carbon material having a high nitrogen content.

  The heat treatment may be any treatment that heats the precursor in the gas phase, and the temperature (maximum temperature) of the heat treatment, the temperature pattern, and the atmosphere around the precursor during the heat treatment can be changed for each heat treatment. The number of heat treatments is preferably 2 to 20 times, more preferably 2 to 10 times, and further preferably 2 to 5 times, from the viewpoint of the properties of the obtained nitrogen-containing carbon material and the process. preferable. Although the apparatus used for heat processing is not specifically limited, For example, a rotary furnace, a tunnel furnace, a tubular furnace, a fluidized-fired furnace is mentioned. The temperature of the heat treatment is preferably increased every time the stage of the heat treatment proceeds from the viewpoint of proceeding carbonization while keeping the nitrogen element content in the precursor high. Although not limited to the following, for example, when the heat treatment is performed twice, the temperature in the second heat treatment is preferably higher than the temperature in the first (first stage) heat treatment. Is preferably 400 to 690 ° C, more preferably 450 to 670 ° C, and still more preferably 500 to 650 ° C. In this case, the ultimate temperature of the second (second stage) heat treatment is preferably 700 to 1200 ° C, more preferably 720 to 1100 ° C, and further preferably 750 to 1050 ° C.

  As the gas in the ambient atmosphere of the precursor during the heat treatment, an inert gas and an activation gas can be selected as appropriate, and one or more kinds can be used. Although not limited to the following gases, for example, examples of the inert gas include nitrogen gas and rare gases (for example, argon gas, helium gas, and neon gas), and examples of the activation gas include air, hydrogen gas, water vapor, and one gas. Examples thereof include carbon oxide gas, carbon dioxide gas, methane gas, oxygen gas, nitric oxide gas, ammonia gas and those diluted with the above inert gas. The activation gas is preferably pure ammonia gas or ammonia-containing gas obtained by diluting pure ammonia with an inert gas from the viewpoint of high nitrogen content of the obtained nitrogen-containing carbon material. Further, the pressure of the gas phase during the heat treatment may be any of normal pressure, pressurization, and reduced pressure (for example, 10 kPa or less, preferably in a vacuum). The gas around the precursor may be stationary or distributed, but is preferably distributed from the viewpoint of the yield of the nitrogen-containing carbon material. Under an inert gas atmosphere, although the specific surface area of the obtained nitrogen-containing carbon material is relatively small, the gasification reaction of azulmic acid in the precursor hardly occurs and carbonization proceeds at a high yield. On the other hand, when the precursor is preferably heat-treated once in an inert gas atmosphere and carbonized to some extent, and then heat-treated in an ammonia-containing gas atmosphere, nitrogen content with a large specific surface area is maintained while maintaining a high nitrogen content. It becomes easy to obtain a carbon material. Therefore, it is preferable to first heat the precursor in an inert gas atmosphere and then perform the heat treatment in an ammonia-containing gas atmosphere.

  The heat treatment time is preferably 10 seconds to 100 hours, more preferably 5 minutes to 50 hours, still more preferably 15 minutes to 20 hours, and particularly preferably 30 minutes to 10 hours per heat treatment. The pressure during the heat treatment is preferably 0.01 to 5 MPa, more preferably 0.05 to 1 MPa, still more preferably 0.08 to 0.3 MPa, and particularly preferably 0.09 to 0.15 MPa. . When the pressure is 5 MPa or less, it is possible to more effectively suppress the nitrogen-containing carbon material from being composed of sp3 orbits and having a low conductivity diamond structure, and when the pressure is 0.01 MPa or more, the airtightness of the equipment Maintenance becomes easier.

  The nitrogen-containing carbon material obtained through each step up to the final heat treatment may contain a transition metal. In the nitrogen-containing carbon material, a part of the transition metal may contribute to the enhancement of the function of the nitrogen-containing carbon material in some form. However, most of the transition metals do not have such an effect, but rather may deteriorate the performance of the nitrogen-containing carbon material. For example, when the iron complex is reduced during the heat treatment to become metallic iron, there is an effect of promoting desorption of nitrogen from the nitrogen-containing carbon material. Therefore, although the removal process is performed between heat treatments, it is preferable to perform the removal process even after the final heat treatment. Also in the removal treatment performed after the final heat treatment, acids represented by sulfuric acid, nitric acid, hydrogen chloride and phosphoric acid and aqueous solutions of these acids can be exemplified, and an aqueous solution of an acid is preferable. The acid concentration in the aqueous acid solution is preferably 1 to 98% by mass, more preferably 10 to 90% by mass, and still more preferably 20 to 80%. The mixing ratio of the acid or the aqueous solution thereof to the nitrogen-containing carbon material containing a transition metal is preferably 1 to 100,000, more preferably 10 to 10,000 in terms of mass ratio. The temperature of the acid or aqueous acid solution in this removal treatment is preferably 0 to 100 ° C, more preferably 10 to 50 ° C.

  From the above viewpoint, the transition metal concentration in the final nitrogen-containing carbon material is preferably 20% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less. .

  The nitrogen-containing carbon material of the present embodiment can be adjusted so as to have a desired average particle diameter depending on its use. When a nitrogen-containing carbon material is used as an electrode, it is preferable to appropriately adjust the average particle diameter ((volume-based median diameter: 50% D)) in order to efficiently exhibit the performance as an electrode. Specifically, in order to improve the specific activity of the electrode, it is preferable that the average particle diameter is small, and the viewpoint that suppresses that the particles are densely aggregated and mass transport is inhibited (for example, solid polymer type) When used as a positive electrode catalyst of a fuel cell, it is preferable that the average particle diameter is large from the viewpoint of preventing oxygen molecules from becoming difficult to be supplied to the active site. From this viewpoint, the average particle diameter of the nitrogen-containing carbon material is preferably 1 nm or more and 100 μm or less, more preferably 5 nm or more and 10 μm or less, and 10 nm or more and 1 μm or less. In general, since azulmic acid and precursor are not melted by heat treatment, the average particle size can be adjusted by granulating or pulverizing azulmic acid and / or precursor before the carbonization step. The precursor may be pulverized during the heat treatment during the carbonization process, or the nitrogen-containing carbon material may be pulverized after the carbonization process, particularly when the average particle diameter of the nitrogen-containing carbon material is 1 μm or less. Although pulverization is suitable, azurmic acid and precursors before heat treatment are highly sticky or soft, and nitrogen-containing carbon material after carbonization process has high hardness. It is preferable to pulverize the precursor from the viewpoint of pulverizing after reducing the tackiness and softness of the precursor as much as possible. The precursor after heat treatment at an ultimate temperature of 200 to 1000 ° C., more preferably 300 to 900 ° C., and even more preferably 400 to 800 ° C. is pulverized. Examples of a method of granulating with a spray dryer when drying a liquid containing an acid and a raw material of a transition metal include, but are not limited to the following methods, but include, for example, a precursor or a nitrogen-containing material. Examples thereof include a method of pulverizing a carbon material with a ball mill, a bead mill, a jet mill or the like.

  The nitrogen-containing carbon material of the present embodiment can also be used, for example, as an exhaust gas purification catalyst that oxidizes harmful substances such as nitric oxide, carbon monoxide, and aromatic hydrocarbons, and a selective oxidation catalyst for benzyl alcohols. It is. In this case, the average particle diameter (volume-based median diameter: 50% D) is preferably 0.1 μm or more and 100 μm or less from the viewpoint of efficiently exhibiting the performance as a catalyst and preventing the loss of the catalyst. More preferably, it is 0.5 μm or more and 30 μm or less.

For electrode or catalyst applications, the specific surface area of the nitrogen-containing carbon material measured by the BET method is preferably in the range of 30 to 2500 m ² / g. By setting the specific surface area to 30 m ² / g or more, various activities can be further enhanced, and by setting the specific surface area to 2500 m ² / g or less, it is easier to synthesize a nitrogen-containing carbon material having such a specific surface area. It becomes. A more preferable range of the specific surface area measured by the BET method is 50 to 1000 m ² / g. In order to increase the specific surface area, chemical activation using potassium hydroxide, sodium hydroxide, zinc chloride, phosphoric acid, etc., and gas activation using carbon dioxide, hydrogen, water vapor, etc. are performed as in the case of general carbon materials. Although it can be used, gas activation using the above ammonia-containing gas or oxygen-containing gas is preferable from the viewpoint of maintaining a high nitrogen content in the nitrogen-containing carbon material.

  The nitrogen-containing carbon material of this embodiment preferably has an atomic ratio (N / C) of nitrogen atoms to carbon atoms of 0.005 to 0.6. In addition, in an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, the diffraction angle (2θ) has a peak at a position of 24.0 to 26.5 °, and the half width of the peak is 7.5 ° or less. Is preferable. When these are within the above numerical range, the nitrogen-containing carbon material can more effectively and reliably exhibit the effects of the present invention.

  The above (N / C) is more preferably 0.04 or more, further preferably 0.05 or more, and particularly preferably 0.06 or more. The (N / C) is more preferably 0.5 or less, still more preferably 0.4 or less, and particularly preferably 0.3 or less.

  The diffraction angle (2θ) is more preferably 25.0 to 26.7 °, still more preferably 25.4 to 26.5 °, and particularly preferably 25.6 to 26.4 °. Has a peak in position. The full width at half maximum of the peak is more preferably 7 ° or less, still more preferably 6 ° or less, and particularly preferably 5 ° or less. The half width of the peak is more preferably 0.001 ° or more, still more preferably 0.01 ° or more, and particularly preferably 0.04 ° or more.

  By increasing the temperature in the heat treatment in the carbonization step to the above-described level, the crystal growth of the nitrogen-containing carbon material becomes more sufficient, the full width at half maximum is further narrowed, and the X-ray diffraction peak comes to be in the above range. Alternatively, the full width at half maximum and the X-ray diffraction peak can be controlled within the above-described range by further firing the nitrogen-containing carbon material obtained as described above at a high temperature of 1200 to 1500 ° C., for example. is there.

  For example, a nitrogen-containing carbon material is prepared, and this is 200 Ncc / min. The temperature was raised to 1000 ° C. over 60 minutes in a nitrogen stream and held at 1000 ° C. for 1 hour, whereby the X-ray diffraction angle (2θ) had a peak at a position of 24.0 to 26.5 °, A nitrogen-containing carbon material having a half width of the peak of 7.5 ° or less can be obtained.

  As can be inferred from the above, when examining the X-ray diffraction peak of a nitrogen-containing carbon material whose firing history is unknown, the X-ray diffraction measurement is performed without firing the test piece of the nitrogen-containing carbon material, and a predetermined diffraction peak is obtained. Is not shown, the test piece was 200 Ncc / min. It is preferable to examine the X-ray diffraction peak after the temperature is raised to 1000 ° C. in a nitrogen flow of 60 minutes and held at 1000 ° C. for 1 hour.

  The nitrogen-containing carbon material of the present embodiment can be used as a material for various electrodes such as a fuel cell electrode typified by a solid polymer type and a metal-air battery electrode, and the activity as the electrode is conventional nitrogen. It is high compared with the contained carbon material. In addition, the nitrogen-containing carbon material of the present embodiment can be used as a catalyst for various chemical reactions, and its activity as a catalyst is higher than that of a conventional nitrogen-containing carbon material.

  The method for producing the electrode containing the nitrogen-containing carbon material of the present embodiment, that is, including the same, is not particularly limited, and can be produced by a general method similar to the conventional carbon material. For example, an electrode can be produced by mixing a nitrogen-containing carbon material and a proton conductive material in a solvent to form a paste, applying the paste directly to the proton conductive membrane, and then drying the applied layer. . Any proton-conducting material can be used as long as it can transmit protons. Nafion (trade name, manufactured by DuPont), Flemion (trade name, manufactured by Asahi Glass), Aciplex (trade name, Asahi Kasei E) And fluorine-containing ion exchange resins having a sulfonic acid group, such as Materials). As the proton conductive membrane, a membrane made of the same material as the proton conductive substance can be used. As a method for producing an electrode, not only a method of directly applying a paste to a proton conductive membrane, but also an electrode is produced by applying a paste on a sheet such as a tetrafluoroethylene sheet, and then the electrode is applied to the proton conductive membrane. A transfer method can also be adopted.

  As a raw material of azulmic acid, hydrocyanic acid obtained as a by-product when a raw material such as propylene or propane reacts in the production of a basic raw material such as acrylonitrile can be used. The method for producing a nitrogen-containing carbon material from azulmic acid produced by heat treating cyanic acid has a small number of steps and a relatively high yield. Therefore, it can be said that it is a method for producing a nitrogen-containing carbon material in order to save resources and energy. Therefore, even when used for an electrode of a fuel cell and a fuel cell obtained by using this electrode, it can be manufactured efficiently and inexpensively with resource saving and energy saving, which is very useful industrially.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said this embodiment. The present invention can be variously modified without departing from the gist thereof.

  EXAMPLES The present invention will be described in more detail with reference to examples of the present invention below, but these are illustrative and the present invention is not limited to the following examples. Those skilled in the art can make various modifications to the embodiments described below and implement the present invention, and such modifications are included in the claims of the present application.

The analysis method was as follows.
<Analysis method>
(Electrochemical measurement)
The measurement method of linear sweep voltammetry by the electrode manufacturing method and the rotating electrode method (using a rotating ring disk electrode device “RRDE-1” manufactured by Nisshi Kogyo) is shown below. First, 5 mg of a nitrogen-containing carbon material is weighed into a vial, and a glass bead is filled with a spatula, 5% by mass of Nafion (trade name) dispersion (manufactured by Sigma Aldrich Japan) is 50 μL, ion-exchanged water and ethanol. 150 μL of each was added, and the mixture was irradiated with ultrasonic waves for 20 minutes to prepare a slurry. 4 μL of this slurry was weighed, applied onto the glassy carbon of the rotating electrode, and dried under saturated steam. The dried rotating electrode was the working electrode, the reversible hydrogen electrode (RHE) was the reference electrode, and the carbon electrode was the counter electrode. 0.5M sulfuric acid was used as an electrolyte solution, and oxygen was bubbled through the electrolyte solution for 30 minutes, and then the electrochemical measurement was performed by sweeping from 1.1 V to 0 V at a sweep speed of 1 mV / s and a rotation speed of 1500 rpm.

<Production example of azulmic acid>
An aqueous solution in which 150 g of hydrocyanic acid was dissolved in 350 g of water was prepared. While stirring, 120 g of a 25% aqueous ammonia solution was added to the aqueous solution over 10 minutes, and the resulting mixture was heated to 35 ° C. Polymerization started and a blackish brown polymer started to precipitate, and the temperature gradually increased to 45 ° C. From 2 hours after the start of polymerization, a 30% by mass aqueous solution of hydrocyanic acid was further added at a rate of 200 g / h, and 800 g was added over 4 hours. During the addition of the aqueous hydrocyanic acid solution, the reaction temperature was controlled to be kept at 50 ° C. The mixture was further stirred at this temperature for 100 hours. The resulting black precipitate was separated by filtration to obtain black azulmic acid. At this time, the yield of azulmic acid with respect to hydrocyanic acid was 96%. The obtained black azulmic acid was washed with water and then dried at 120 ° C. for 4 hours in a dryer.

[Comparative Example 1]
<Precursor preparation>
To the 1 L eggplant-shaped flask were added 6.0 g of azulmic acid after drying, 0.55 g of iron (III) nitrate nonahydrate and 400 g of pure water, and the mixture was stirred in an oil bath at 90 ° C. for 1 hour. Then, the solvent was removed with a rotary evaporator and dried at 80 ° C. for 8 hours with a vacuum dryer to obtain a precursor.

<Synthesis of nitrogen-containing carbon materials>
1.0 g of the obtained precursor was placed on a quartz boat, which was placed in a quartz tubular furnace having an inner diameter of 36 mm, and the furnace was heated from room temperature to 600 at room temperature over 60 minutes under a nitrogen flow of atmospheric pressure and 1 NL / min. The temperature was raised to 0 ° C. and kept at 600 ° C. for 5 hours. After cooling to room temperature, this was pulverized and classified with a planetary ball mill (manufactured by Fritsch, trade name “Pulverisete-7”) to adjust the average particle size to about 2 μm. Thereafter, the precursor after classification is immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a part of iron from the precursor, and finally the nitrogen-containing carbon material 0.29 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Comparative Example 2]
<Synthesis of nitrogen-containing carbon materials>
1.0 g of the precursor prepared in “Preparation of Precursor” of Comparative Example 1 was placed on a quartz boat, accommodated in a quartz tube furnace having an inner diameter of 36 mm, and the inside of the furnace was fed with nitrogen at atmospheric pressure and 1 NL / min. The temperature was raised from room temperature to 800 ° C. over 80 minutes and kept at 800 ° C. for 1 hour. After cooling to room temperature, this was pulverized and classified with a planetary ball mill (manufactured by Fritsch, trade name “Pulverisete-7”) to adjust the average particle size to about 2 μm. Thereafter, the precursor after classification is immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a part of iron from the precursor, and finally the nitrogen-containing carbon material 0.15 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Example 1]
<Synthesis of nitrogen-containing carbon materials>
As a precursor, 0.29 g of a nitrogen-containing carbon material synthesized by the same method as “Synthesis of nitrogen-containing carbon material” in Comparative Example 1 was used. It was placed on a quartz boat and housed in a quartz tube furnace having an inner diameter of 36 mm. The inside of the furnace was heated from room temperature to 800 ° C. over 20 minutes under an atmospheric pressure, 1 NL / min ammonia gas flow. It was kept for 1 hour. After cooling to room temperature, this was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a portion of the iron, and finally the nitrogen-containing carbon material 0.04 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Example 2]
<Synthesis of nitrogen-containing carbon materials>
As a precursor, 0.20 g of a nitrogen-containing carbon material synthesized by the same method as “Synthesis of nitrogen-containing carbon material” in Example 1 was used. It was placed on a quartz boat and housed in a quartz tube furnace having an inner diameter of 36 mm, and the temperature inside the furnace was increased from room temperature to 1000 ° C. over 20 minutes under the flow of ammonia gas at atmospheric pressure and 1 NL / min. It was kept for 1 hour. After cooling to room temperature, this was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a portion of the iron, and finally the nitrogen-containing carbon material 0.05 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Comparative Example 3]
<Precursor preparation>
To a 1 L eggplant-shaped flask, 80 g of ethylenediamine and 200 g of pure water were added and stirred to prepare an ethylenediamine aqueous solution. Thereto was added 6.0 g of the dried azulmic acid, and the mixture was stirred in an oil bath at 90 ° C. for 1 hour. Next, 1.8 g of iron phthalocyanine was added thereto and again stirred in an oil bath at 90 ° C. for 1 hour. Then, the solvent was removed with a rotary evaporator and dried at 80 ° C. for 8 hours with a vacuum dryer to obtain a precursor.

<Synthesis of nitrogen-containing carbon materials>
1.0 g of the obtained precursor was placed on a quartz boat, which was placed in a quartz tube furnace having an inner diameter of 36 mm, and the inside of the furnace was heated from room temperature to 800 ° C. over 80 minutes under nitrogen flow at atmospheric pressure and 1 NL / min. The temperature was raised to 0 ° C. and kept at 800 ° C. for 5 hours. After cooling to room temperature, this was pulverized and classified with a planetary ball mill (manufactured by Fritsch, trade name “Pulverisete-7”) to adjust the average particle size to about 2 μm. Thereafter, the precursor after classification is immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a part of iron from the precursor, and finally the nitrogen-containing carbon material 0.36 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Example 3]
<Synthesis of nitrogen-containing carbon materials>
1.0 g of the precursor prepared in “Preparation of Precursor” of Comparative Example 3 was placed on a quartz boat, accommodated in a quartz tube furnace having an inner diameter of 36 mm, and nitrogen flow in the furnace at atmospheric pressure and 1 NL / min. The temperature was raised from room temperature to 600 ° C. over 60 minutes and kept at 600 ° C. for 5 hours. After cooling to room temperature, this was pulverized and classified with a planetary ball mill (manufactured by Fritsch, trade name “Pulverisete-7”) to adjust the average particle size to about 2 μm. Thereafter, the precursor after classification was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours, and then filtered three times to remove at least a part of iron from the precursor. Further, the precursor after the removal treatment was placed in a quartz boat in a total amount and accommodated in a quartz tube furnace having an inner diameter of 36 mm, and the inside of the furnace was heated from room temperature to 800 ° C. over 20 minutes under an ammonia gas flow of atmospheric pressure and 1 NL / min. And kept at 800 ° C. for 1 hour. After cooling to room temperature, this was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a portion of the iron, and finally the nitrogen-containing carbon material 0.05 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Comparative Example 4]
<Precursor preparation>
Into a 1 L eggplant-shaped flask, 6.0 g of azulmic acid, 0.93 g of cobalt (II) nitrate hexahydrate and 400 g of pure water were added, and the mixture was stirred in a 90 ° C. oil bath for 1 hour. Then, the solvent was removed with a rotary evaporator and dried at 80 ° C. for 8 hours with a vacuum dryer to obtain a precursor.

<Synthesis of nitrogen-containing carbon materials>
1.0 g of the obtained precursor was placed on a quartz boat, which was placed in a quartz tubular furnace having an inner diameter of 36 mm, and the furnace was heated from room temperature to 600 at room temperature over 60 minutes under a nitrogen flow of atmospheric pressure and 1 NL / min. The temperature was raised to 0 ° C. and kept at 600 ° C. for 5 hours. After cooling to room temperature, a planetary ball mill by grinding and classifying at (Fritsch, Ltd., trade name "Pulverisette-7"), to adjust the average particle size of about 2 [mu] m. Thereafter, the precursor after classification is immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a part of cobalt from the precursor, and finally the nitrogen-containing carbon material 0.30 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[ Comparative Example 5 ]
<Synthesis of nitrogen-containing carbon materials>
1.0 g of the precursor prepared in “Precursor synthesis” of Comparative Example 4 was placed on a quartz boat, and it was housed in a quartz tube furnace having an inner diameter of 36 mm, and the inside of the furnace was supplied with nitrogen at atmospheric pressure and 1 NL / min. The temperature was raised from room temperature to 600 ° C. over 60 minutes and kept at 600 ° C. for 5 hours. After cooling to room temperature, this was pulverized and classified with a planetary ball mill (manufactured by Fritsch, trade name “Pulverisete-7”) to adjust the average particle size to about 2 μm. Thereafter, at least a part of the cobalt was removed by immersing the classified precursor in concentrated hydrochloric acid and filtering. Furthermore, the precursor after the removal treatment was placed in a quartz boat in a total amount, and the temperature was raised from room temperature to 800 ° C. over 20 minutes in a quartz tube furnace having an inner diameter of 36 mm under a nitrogen flow of atmospheric pressure and 1 NL / min. It was kept at 800 ° C. for 1 hour. After cooling to room temperature, this was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours, and then filtered three times to remove at least a part of cobalt , and finally the nitrogen-containing carbon material was removed. 0.04 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

[Example 4 ]
<Synthesis of nitrogen-containing carbon materials>
1.0 g of the precursor prepared in the same manner as “Synthesis of Precursor” in Comparative Example 1 was placed on a quartz boat and accommodated in a quartz tubular furnace having an inner diameter of 36 mm, which was passed through nitrogen at an atmospheric pressure of 1 NL / min. The temperature was raised from room temperature to 500 ° C. over 60 minutes and kept at 500 ° C. for 5 hours. After cooling to room temperature, this was pulverized and classified with a planetary ball mill (manufactured by Fritsch, trade name “Pulverisete-7”) to adjust the average particle size to about 2 μm. Thereafter, the precursor after classification was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to obtain 0.29 g of a precursor from which at least a part of iron had been removed. 0.29 g of this precursor was placed on a quartz boat, accommodated in a quartz tube furnace having an inner diameter of 36 mm, and the inside of the furnace was heated from room temperature to 800 ° C. over 20 minutes under the flow of ammonia gas at atmospheric pressure and 1 NL / min. And kept at 800 ° C. for 1 hour. After cooling to room temperature, this was immersed in 400 mL of 33% by mass hydrochloric acid, stirred for 2 hours and then filtered three times to remove at least a portion of the iron, and finally the nitrogen-containing carbon material 0.04 g was obtained. The electrochemical measurement was performed on the obtained nitrogen-containing carbon material. Table 1 shows currents when the potential is 0.5V.

  The nitrogen-containing carbon material of the present invention is useful as a catalyst for a chemical reaction in addition to various electrodes such as an electrode for a fuel cell and an electrode for a metal-air battery. Further, the method for producing a nitrogen-containing carbon material of the present invention can use a polymer of cyanuric acid produced as a by-product in the production of basic raw materials such as acrylonitrile, has a small number of steps, and has a carbonization yield. high. Therefore, it is useful as a production method that saves resources and energy.

Claims (4)

Having a step of carbonizing a precursor of a nitrogen-containing carbon material containing azulmic acid and iron ,
The step includes a first step of performing a first heat treatment on the precursor, a second step of removing at least a part of the iron from the precursor subjected to the first heat treatment, and at least a portion of the iron . a third step of performing second heat treatment on a part has been removed the precursor, was closed,
In the third step, the atmosphere around the precursor is an ammonia-containing gas atmosphere.
A method for producing a nitrogen-containing carbon material.   The manufacturing method according to claim 1, further comprising a fourth step of pulverizing the precursor between the first step and the third step.   The manufacturing method according to claim 1, wherein in the first step, the atmosphere around the precursor is an inert gas atmosphere. In the third step, the ammonia-containing gas atmosphere of pure ammonia gas, or pure ammonia gas What ammonia-containing gas atmosphere der diluted with an inert gas, the precursor around the gas is circulated, wherein Item 4. The method according to any one of Items 1 to 3.