JP6315831B2 - Method for hydrolysis of cellulose - Google Patents

Description

  The present invention relates to a carbonaceous material containing amorphous carbon and a method for producing the same. Moreover, this invention relates to the solid acid and adsorbent which consist of the said carbonaceous material. Furthermore, this invention relates to the hydrolysis method using the solid acid which consists of said carbonaceous material as a catalyst.

  Amorphous carbon is used in various fields because it has excellent thermal and chemical stability and can be produced at low cost. Amorphous carbon generally refers to carbon that does not have a clear crystal structure, such as diamond or graphite. Amorphous carbon can be obtained by a method of carbonizing an organic substance under relatively mild conditions.

  By the way, in recent years, a technique for adding a new function to a carbonaceous material by chemically treating the carbonaceous material such as amorphous carbon is known.

  Patent Documents 1 and 2 disclose that amorphous carbon into which sulfo groups are introduced can be obtained by heat-treating polycyclic aromatic hydrocarbons such as naphthalene, anthracene, perylene, coronene in concentrated sulfuric acid or fuming sulfuric acid. Is described.

  Patent Document 3 describes that amorphous carbon can be obtained by using cellulose as an organic substance and carbonizing the cellulose at 450 ° C. for 5 hours. It is described that amorphous carbon into which a sulfo group is introduced can be obtained by heat-treating the amorphous carbon in concentrated sulfuric acid or fuming sulfuric acid. It is described that this amorphous carbon having a sulfo group introduced is thermally and chemically stable and acts as a solid acid.

  In a carbonaceous material having an acidic functional group (acid point) such as a sulfo group, the utility value increases as the acid point increases. For example, when a carbonaceous material into which a sulfo group has been introduced is used as an acid catalyst, if the acid point increases, the active point in the catalytic reaction increases and the utility value as an acid catalyst increases. Further, when a carbonaceous material having a sulfo group introduced therein is used as an adsorbent, the adsorbing point increases as the acid point increases, resulting in an excellent adsorbent. Therefore, development of a carbonaceous material having a higher acid point has been desired.

Japanese Patent Laid-Open No. 2004-238111 International Publication No. 2005/029508 JP 2009-268960 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a carbonaceous material containing amorphous carbon and having a high acid point, and a method for producing the same.

The above-mentioned problem is a method for hydrolyzing cellulose using as a catalyst a solid acid made of a carbonaceous material containing amorphous carbon; the amorphous carbon includes a graphene sheet;
The carbonaceous material has a sulfo group, the ratio of sulfur atom to carbon atom (S / C) is 0.005 to 0.15, and peaks in the range of 175 to 200 ° C. in the ammonia temperature programmed desorption method. The acid point number determined from the amount of ammonia desorbed at 100 to 400 ° C. is 30 μmol / g or more, and the total pore volume determined by the BJH method is 0.02 to 1 cm ³ / g. It is solved by providing a method for hydrolyzing cellulose, characterized in that the average pore diameter is 2 to 30 nm and the total ratio of metal atoms to carbon atoms (Metal / C) is 0.5 or less. The In addition, the above-described problem is a method for hydrolyzing cellulose using a solid acid composed of a carbonaceous material containing amorphous carbon as a catalyst ; the amorphous carbon includes a graphene sheet, and the carbonaceous material has a sulfo group. The ratio of sulfur atoms to carbon atoms (S / C) is 0.005 to 0.15, and in the ammonia temperature programmed desorption method, the peak temperature is in the range of 175 to 200 ° C, and the temperature is 100 to 400 ° C. The number of acid points determined from the amount of ammonia desorbed in the above is 30 μmol / g or more, metal oxide particles are dispersed in the amorphous carbon matrix, and the total ratio of metal atoms to carbon atoms This can also be solved by providing a method for hydrolyzing cellulose, wherein (Metal / C) is 0.001 to 0.5.

At this time, the ratio of hydrogen atoms to carbon atoms (H / C) is preferably less than 1 .

It is also preferable that the coercive force is 500 Oe or less and the saturation magnetization is 0.1 emu / g or more.

  According to the present invention, it is possible to provide a carbonaceous material containing amorphous carbon and having many acid points, and a method for producing the same.

It is the figure which showed the result of the differential scanning calorimetry of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the result of the differential scanning calorimetry of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the scanning electron micrograph (SEM image) of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the scanning electron micrograph (SEM image) of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the transmission electron micrograph (TEM image) of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the transmission electron micrograph (TEM image) of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the transmission electron micrograph (TEM image) of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the transmission electron micrograph (TEM image) of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the transmission electron micrograph (TEM image) of the carbonaceous material of Example 2 after a sulfonation process. It is the figure which showed the transmission electron micrograph (TEM image) of the carbonaceous material of Example 5 after a sulfonation process. It is the figure which showed the pore distribution curve analyzed by the BJH method of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the pore distribution curve analyzed by BJH method of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the pore distribution curve analyzed by the BJH method of the carbide | carbonized_material of Example 6 before a sulfonation process. It is the figure which showed the pore distribution curve analyzed by HK method of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the pore distribution curve analyzed by HK method of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the qualitative analysis result by the powder X-ray diffraction method of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the qualitative analysis result by the powder X ray diffraction method of the carbide | carbonized_material of Example 6 before a sulfonation process. It is the figure which showed the result of the X-ray photoelectron spectroscopy wide scan measurement of the carbide | carbonized_material of Example 1 before a sulfonation process. It is the figure which showed the result of the X-ray photoelectron spectroscopy wide scan measurement of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the result of the X-ray photoelectron spectroscopy narrow scan measurement ( _O1s ) of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the result of the X-ray photoelectron spectroscopy narrow scan measurement ( _C1s ) of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the result of the X-ray photoelectron spectroscopy narrow scan measurement ( _Fe2p ) of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the result of the X-ray photoelectron spectroscopy narrow scan measurement ( _S2p ) of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the analysis result by Mossbauer spectroscopy of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the infrared spectroscopy measurement result of the carbonaceous material of Example 1 after sulfonation treatment and the carbide | carbonized_material of Example 1 before sulfonation treatment. It is the figure which showed the result of the ¹³ C-NMR measurement of the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the measurement result by the ammonia thermal desorption method of the carbonaceous material of Examples 1-5 after a sulfonation process. It is the figure which showed the result of the Raman spectroscopic measurement of the carbide | carbonized_material of Example 1 before a sulfonation process, and the carbonaceous material of Example 1 after a sulfonation process. It is the figure which showed the magnetization curve of the carbonaceous material of Example 1 after sulfonation treatment and the carbide | carbonized_material of Example 1 before sulfonation treatment. It is the figure which showed the magnetization curve of the carbonaceous material of Examples 1-5 after a sulfonation process. It is the figure which showed the magnetization curve of the carbide | carbonized_material of Example 6 before a sulfonation process. It is the figure which showed the magnetization curve of the carbide | carbonized_material of Example 8 before a sulfonation process. It is the figure which showed collectively the magnetization curve of FIG. It is the figure which showed the result of the liquid chromatography measurement of the cellulose hydrolysis reaction product which used the carbonaceous material of Example 1 after a sulfonation process as an acid catalyst.

  The carbonaceous material of the present invention contains amorphous carbon. Here, amorphous carbon generally refers to a substance made of carbon that does not have a clear crystal structure, such as diamond or graphite. It can be confirmed by measurement by X-ray diffraction that the carbonaceous material of the present invention contains amorphous carbon. Amorphous carbon does not detect a sharp peak in X-ray diffraction, or even if a peak is detected, the shape of the peak is broad. For example, in the case of the carbonaceous material obtained in the Examples of the present application, a broad peak is observed in the powder X-ray diffraction pattern near the half width (2θ) of 10 to 30 °, and the carbonaceous material contains amorphous carbon. It can be seen that it does not contain carbon with a clear crystal structure.

In the carbonaceous material of the present invention, amorphous carbon includes a graphene sheet. Here, the graphene sheet has a structure in which aromatic rings are condensed and connected on a two-dimensional plane. When the carbonaceous material includes a graphene sheet, a peak called a D band due to a carbon atom having a dangling bond is detected in the vicinity of 1350 cm ^{−1 in} the Raman spectrum.

  The average size of the graphene sheet can be calculated based on the ratio (D / G) of the D band peak intensity to the G band peak intensity by Raman spectrum. For example, in the carbonaceous material obtained in the example of the present application, the ratio (D / G) was about 0.8, and the average size of the graphene sheet contained therein was about 1 nm. In general, a small ratio (D / G) indicates that the graphene sheet is large in size, and the resulting amorphous carbon has a homogeneous and stable structure. On the other hand, when the ratio (D / G) is large, the resulting amorphous carbon is chemically active. The ratio (D / G) is preferably 0.1 to 2.25, and more preferably 0.5 to 2.0.

  The carbonaceous material of the present invention has a sulfo group, and the ratio of sulfur atom to carbon atom (S / C) is 0.005 to 0.15. When the ratio of sulfur atoms to carbon atoms is less than 0.005, the amount of sulfo groups (acidic functional groups) introduced into the carbonaceous material decreases, and a carbonaceous material having many acid sites cannot be obtained. On the other hand, if the ratio of the sulfur atom to the carbon atom exceeds 0.15, the graphene sheet does not grow, and a carbonaceous material containing amorphous carbon cannot be obtained. In addition to the sulfo group, the carbonaceous material of the present invention may have other acidic functional groups such as a carboxyl group and a hydroxyl group.

  The carbonaceous material of the present invention has a peak temperature in the range of 175 to 200 ° C. in the ammonia temperature-programmed desorption method, and has an acid score of 30 μmol / g or more determined from the amount of ammonia desorbed at 100 to 400 ° C. It is characterized by being. Conventionally, it is known that a solid acid in which a sulfo group is introduced into amorphous carbon can be obtained by carbonizing and sulfonating cellulose. The carbonaceous material of the present invention is characterized by having more acid sites than conventional solid acids. When the acid point is less than 30 μmol / g, when the carbonaceous material of the present invention is used as a solid acid or an adsorbent, there is a possibility that excellent performance cannot be obtained. The acid point is preferably 50 μmol / g or more, and more preferably 100 μmol / g or more. On the other hand, the upper limit of the acid score is not particularly limited, but the acid score is usually 1000 μmol / g or less.

Here, ammonia temperature desorption method (hereinafter, may be abbreviated as NH ₃ -TPD method) and, after adsorbing the ammonia to the solid sample, continuously heated by controlling a constant heating rate The amount of ammonia desorbed and the desorption temperature are measured. In the NH ₃ -TPD method, ammonia adsorbed at a weak acid site is desorbed at a low temperature, and ammonia adsorbed at a strong acid site is desorbed at a high temperature. Therefore, the acid strength of the solid sample can be measured from the peak temperature, and the acid point number of the solid sample can be measured from the total amount of desorbed ammonia.

  The carbonaceous material of the present invention preferably has a ratio of hydrogen atoms to carbon atoms (H / C) of less than 1. When the ratio (H / C) is 1 or more, carbonization becomes insufficient, and amorphous carbon may not be obtained. The ratio (H / C) is more preferably 0.8 or less. On the other hand, the ratio (H / C) is preferably 0.1 or more. When the ratio (H / C) is less than 0.1, the graphene sheet in the carbonaceous material grows too much and is chemically stabilized, and acidic functional groups such as sulfo groups can be introduced into the carbonaceous material. May be difficult. The ratio (H / C) is more preferably 0.2 or more.

In the carbonaceous material of the present invention, the total pore volume determined by the BJH method is preferably 0.02 to 1 cm ³ / g. When the total pore volume is less than 0.02 cm ³ / g, it may be difficult to introduce acidic functional groups such as sulfo groups into the carbonaceous material. On the other hand, if the total pore volume exceeds 1 cm ³ / g, the mechanical strength of the carbonaceous material may be reduced.

  In the carbonaceous material of the present invention, the average pore diameter determined by the BJH method is preferably 2 to 30 nm. When the average pore diameter is less than 2 nm, it may be difficult to introduce acidic functional groups such as sulfo groups into the carbonaceous material. On the other hand, if the average pore diameter exceeds 30 nm, the mechanical strength of the carbonaceous material may decrease.

It is also preferred that the carbonaceous material of the present invention has a BET specific surface area of 10 to 300 m ² / g. If the BET specific surface area is less than 10 m ² / g, it may be difficult to introduce acidic functional groups such as sulfo groups into the carbonaceous material, while if the BET specific surface area exceeds 300 m ² / g, carbon The mechanical strength of the quality material may be reduced.

In the present invention, in order to obtain a carbonaceous material having many acid points, it is preferable to carbonize a mixture of a water-soluble metal salt and a water-soluble polysaccharide and then to perform a sulfonation treatment. In the carbonaceous material obtained at this time, metal oxide particles are preferably dispersed in an amorphous carbon matrix. Metal oxide is not particularly limited, iron, cobalt, nickel, chromium, manganese, magnesium, vanadium, yttrium, titanium, zirconium, ruthenium, rhodium, palladium, silver, cadmium, indium, aluminum, tin, sodium, lithium, Beryllium, potassium, calcium, scandium, rubidium, strontium, gallium, copper, molybdenum, zinc, cesium, platinum, gold, iridium, thorium, thallium, bismuth, lead, mercury, cerium, lanthanum, tungsten, niobium, neodymium, barium, Examples thereof include oxides such as gadolinium, samarium, and dysprodium. In particular, when particles that react with magnetic force, such as oxides of iron, cobalt, nickel, chromium, manganese, barium, gadolinium, samarium, dysprodium, are dispersed in an amorphous carbon matrix, carbon is generated by an external magnetic field. The movement of the quality material can be controlled. When the oxide is iron oxide, the type of iron oxide is not particularly limited, but examples include magnetite (Fe ₃ O ₄ ), hematite (α-Fe ₂ O ₃ ), and maghemite (γ-Fe ₂ O ₃ ). The The amorphous carbon matrix may contain a sulfate, and examples thereof include iron (III) sulfate (Fe ₂ (SO ₄ ) ₃ ).

  The oxide particles are preferably fine. The average particle size of the oxide particles is preferably 2 to 100 nm, and more preferably 5 to 50 nm. Here, the average particle diameter of the oxide particles is obtained by taking a transmission electron micrograph (TEM image) of the carbonaceous material and measuring the diameter of the particles in the obtained photograph. If the particles are not circular, the equivalent circle diameter is the diameter.

  In the carbonaceous material of the present invention, when metal oxide particles are dispersed in an amorphous carbon matrix, the total ratio of metal atoms to carbon atoms (Metal / C) is 0.001 to 0.5. It is preferable that If the ratio of metal atoms to carbon atoms (Metal / C) is less than 0.001, the acid score may be lowered. In addition, when the metal atom is iron, cobalt, nickel, chromium, manganese, barium, gadolinium, samarium, dysprodium or the like, the carbonaceous material is insufficiently magnetized, and it may be difficult to control the movement by an external magnetic field. The total ratio of metal atoms to carbon atoms (Metal / C) is preferably 0.005 or more, and more preferably 0.01 or more. On the other hand, if the total ratio of metal atoms to carbon atoms (Metal / C) exceeds 0.5, it may be difficult to introduce acidic functional groups such as sulfo groups into the carbonaceous material. The ratio of the total number of metal atoms to carbon atoms (Metal / C) is preferably 0.25 or less, and more preferably 0.1 or less.

  When the metal oxide particles contained in the carbonaceous material are metal oxides that react with magnetic force, it is preferable that the coercive force is small, that is, soft magnetism. Specifically, the coercive force is preferably 500 Oe or less, more preferably 200 Oe or less, and further preferably 100 Oe or less. When the coercive force exceeds 500 Oe, residual magnetization increases, and carbonaceous materials may be magnetically aggregated. Therefore, it is preferable that hysteresis is hardly seen in the magnetization curve of the carbonaceous material of the present invention.

  The saturation magnetization of the carbonaceous material is preferably 0.1 emu / g or more. When the saturation magnetization is less than 0.1 emu / g, the responsiveness of the carbonaceous material to an external magnetic field is not preferable. The saturation magnetization is more preferably 2 emu / g or more. On the other hand, the upper limit of saturation magnetization is not particularly limited as long as it does not impair the effects of the present invention, but is usually 100 emu / g or less.

  The production method of the carbonaceous material of the present invention is not particularly limited, but the preferred production method includes a first step of mixing a water-soluble metal salt and a water-soluble polysaccharide in the presence of water. The second step of carbonizing the mixture obtained in the first step and the third step of sulfonating the carbide obtained in the second step are provided.

  The metal salt used in the first step is not particularly limited as long as it is a water-soluble metal salt. The cation component of the metal salt is not particularly limited, and iron, cobalt, nickel, chromium, manganese, magnesium, vanadium, yttrium, titanium, zirconium, ruthenium, rhodium, palladium, silver, cadmium, indium, aluminum, tin, sodium, Lithium, beryllium, potassium, calcium, scandium, rubidium, strontium, gallium, copper, molybdenum, zinc, cesium, platinum, gold, iridium, thorium, thallium, bismuth, lead, mercury, cerium, lanthanum, tungsten, niobium, neodymium, Examples include ions such as barium, gadolinium, samarium, dysprodium. Above all, when the cation component of the metal salt is an ion such as iron, cobalt, nickel, chromium, manganese, barium, gadolinium, samarium, dysprodium, etc., an oxide that can control the movement of the carbonaceous material by an external magnetic field Particles can be formed. The anion component of the metal salt is not particularly limited, and examples thereof include nitrate ion, chloride ion, sulfate ion, phosphate ion, carbonate ion, borate ion, and carboxylic acid. Among these, as the anion component of the metal salt, nitrate ions are preferable because the decomposition temperature is low and the anion component does not remain after decomposition. In the first step, one type of metal salt can be used alone, or two types of metal salts can be used in combination.

  The polysaccharide used in the first step is not particularly limited as long as it is a water-soluble polysaccharide. Examples of the polysaccharide include cellulose derivatives and salts thereof, starch, dextrin and the like. Among these, a cellulose derivative and a salt thereof are preferable, and a salt of a cellulose derivative is more preferable. Preferred examples of the cellulose derivative include carboxymethyl cellulose, and examples of the salt include alkali metal salts. When a water-soluble polysaccharide is used in the first step, it can be dissolved in water when a carbonaceous material is synthesized. By dissolving the metal salt in the aqueous solution in which the polysaccharide is dissolved, the metal oxide particles can be dispersed in the amorphous carbon matrix by a subsequent carbonization treatment. Therefore, when obtaining a carbonaceous material in which metal oxide particles are dispersed in an amorphous carbon matrix, it is preferable to use a water-soluble polysaccharide.

  The mixing operation in the first step is not particularly limited. The polysaccharide powder may be added to and mixed with the metal salt aqueous solution, or the metal salt powder may be added to and mixed with the polysaccharide aqueous solution. Metal salt powder and polysaccharide powder may be added to water and mixed. Further, an aqueous solution of a metal salt and an aqueous solution of a polysaccharide may be mixed. The kind of water used at this time is not limited, and not only sufficiently purified water such as ion exchange water and distilled water but also tap water can be used.

  Next, in the second step, the mixture obtained in the first step is carbonized to obtain a carbide. The carbonization treatment is preferably performed by heating in an inert gas atmosphere such as argon gas or nitrogen gas. It is also preferable to carbonize the mixture obtained in the first step after drying in advance to remove moisture. The drying method is not particularly limited, and heat drying, reduced pressure drying, or the like can be employed. Although the drying temperature at the time of heat-drying will not be specifically limited if it is the temperature which can remove the water | moisture content in a mixture, It is suitable that it is 40 degreeC or more. When the drying temperature is less than 40 ° C., there is a possibility that water in the mixture cannot be sufficiently removed. The drying temperature is more preferably 60 ° C. or higher. Further, the drying temperature is usually 100 ° C. or less from the viewpoint of energy consumption and cost. The drying temperature at this time is a set temperature in the drying apparatus used for drying the mixture. The drying time is set in relation to the drying temperature, but may be set as appropriate so that water in the mixture can be sufficiently removed.

  The heating temperature in the second step is not particularly limited as long as the carbonization of the mixture proceeds, but is preferably 80 ° C. or higher. When the heating temperature is less than 80 ° C., the carbonization of the polysaccharide may be insufficient. Further, when a carbonaceous material in which metal oxide particles are dispersed in an amorphous carbon matrix is to be produced, if the heating temperature is less than 80 ° C., the metal salt may not be oxidized. The heating temperature at this time is a set temperature in the heating device used for carbonization of the mixture. The mixture obtained in the first step depends on the dry state and the type of metal salt used, but when heated to 80 ° C. or higher, self-combustion starts and the temperature of the mixture itself reaches 400 ° C. or higher to cause carbonization. be able to. The heating temperature is more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher. On the other hand, it is also preferable that the heating temperature is 1000 ° C. or lower. When the heating temperature exceeds 1000 ° C., the graphene sheet in the carbonaceous material grows too much as a result of the progress of carbonization, which may make it difficult to introduce sulfo groups in the subsequent third step. From the viewpoint of energy consumption and cost, the heating temperature is more preferably 800 ° C. or less, and more preferably 600 ° C. or less. The heating time is set in relation to the heating temperature, but may be set as appropriate so that the carbonization of the polysaccharide proceeds sufficiently.

  Moreover, a heating apparatus is not specifically limited, Any heating apparatus of an electric heating type, a hot air type, and a direct fire type can be used. In addition, a dust collector may be connected to the heating device in order to separate the gas generated by carbonization of the mixture from the solid particles contained in the gas. The dust collector is not particularly limited, and examples thereof include a cyclone dust collector and a filter dust collector. From the viewpoint of uniformity of carbonization treatment and continuous productivity of carbides, it is preferable to industrially use a rotary kiln to carbonize the mixture. Further, the generated gas is preferably exhausted after being previously washed with water or the like.

  The particle size of the carbide obtained in the second step is usually about several μm to several hundred μm, but it can be made finer by pulverization. In addition, a water-soluble metal salt or a water-soluble polysaccharide as a raw material may remain in the carbide obtained in the second step. Therefore, a step of washing carbide may be further added between the second step and the third step. By washing the carbide, metal salts and the like are removed, and a carbide having a larger specific surface area can be obtained.

  The method for washing the carbide is not particularly limited, such as a method of bringing water and carbide into contact with each other and extracting a metal salt contained in the carbide, a method of mixing water and carbide and then filtering using a filter medium, etc. Is mentioned. A Soxhlet extractor or the like can be used for extraction, and a Kiriyama funnel, a Buchner funnel, or the like can be used for filtration. Although the washing | cleaning liquid used for washing | cleaning is not specifically limited, Distilled water, ion-exchange water, etc. can be used. Further, an aqueous solution containing a small amount of acid such as hydrochloric acid or acetic acid may be used in order to efficiently remove metal salts and the like.

  Next, in the third step, the carbide obtained in the second step is sulfonated to obtain the carbonaceous material of the present invention. The sulfonation treatment method in the third step is not particularly limited as long as it is a method capable of introducing a sulfo group into the carbide, and examples thereof include a method using fuming sulfuric acid or concentrated sulfuric acid. At this time, it is preferable to treat with a mixed solution of fuming sulfuric acid and concentrated sulfuric acid, and heating is also preferable. The particle size of the carbonaceous material thus obtained is usually about several μm to several hundred μm, but it can be made finer by pulverization. Moreover, the carbonaceous material of a desired particle size can also be obtained by sieving using a sieve etc.

  A preferred embodiment of the present invention is a solid acid made of the above carbonaceous material. Since the carbonaceous material of the present invention has many strong acid sites on the surface, it becomes an excellent solid acid. In the carbonaceous material of the present invention, when metal oxide particles that react with magnetic force are dispersed in an amorphous carbon matrix, the movement of the carbonaceous material can be controlled by an external magnetic field. Therefore, it can also be used as a solid acid whose movement can be controlled by an external magnetic field.

  A preferred embodiment of the present invention is a cellulose hydrolysis method characterized by hydrolyzing cellulose using the solid acid as a catalyst. Using the carbonaceous material of the present invention as a catalyst, it was confirmed that when cellulose was hydrolyzed (saccharified), cellulose was hydrolyzed to produce disaccharide cellobiose and monosaccharide glucose. . Furthermore, it was also confirmed that organic acids such as levoglucosan and formic acid, which are glucose degradation products, were produced. Further, in the above hydrolysis experiment, when metal oxide particles that react with magnetic force are dispersed in an amorphous carbon matrix, a stirrer is not put in a container containing cellulose and a carbonaceous material. It was also confirmed that the carbonaceous material can be stirred by an external magnetic field.

  A preferred embodiment of the present invention is an adsorbent made of the above carbonaceous material. Since the carbonaceous material of the present invention is porous and has many acid sites on its surface, it becomes an excellent adsorbent. The substance to be adsorbed on the carbonaceous material is not particularly limited, and examples thereof include alkali metal ions such as cesium ions, alkaline earth metal ions such as strontium ions, basic molecules such as methylene blue, and iodine. Since the carbonaceous material of the present invention has many strong acid sites (acidic functional groups) on the surface, an alkaline substance is suitable as the substance to be adsorbed.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
Iron (III) nitrate nonahydrate the _{(Fe (NO 3) 3 ·} 9H 2 O) 0.500g to obtain an aqueous solution of iron nitrate dissolved in water 100 ml. 1.0 g of powdered sodium carboxymethylcellulose (manufactured by Wako Pure Chemical Industries, Ltd., model number: 039-01335, hereinafter sometimes abbreviated as CMC · Na) is added to the obtained aqueous solution and stirred to obtain a gel-like precipitate. I got a thing. And it dried at 60 degreeC for about 5 days using the constant temperature drying furnace until the water | moisture content of the obtained gel-like deposit was lost. Thereafter, the dried precipitate was transferred to a three-necked flask, and carbonized by heating at 200 ° C. for 1 hour in a nitrogen atmosphere in the three-necked flask to obtain a carbide.

Then, 5 g of the obtained carbide was put into a mixed solution of 75 ml of fuming sulfuric acid (SO ₃ concentration 20%) and 75 ml of concentrated sulfuric acid (concentration 96%), and stirred in a three-necked flask at 80 ° C. for 10 hours in a nitrogen atmosphere. And then sulfonated. Thereafter, the obtained carbide was washed with 3000 ml of distilled water and dried at 105 ° C. to obtain 5 g of a carbonaceous material.

Examples 2-5
The amount of iron (III) nitrate nonahydrate dissolved in 100 ml of water was 0.125 g (Example 2), 0.250 g (Example 3), 1.00 g (Example 4), 1.50 g (Example). After changing to 5) to obtain a carbide, a carbide was obtained in the same manner as in Example 1 except that the carbide was washed with distilled water for 6 hours or more using a Soxhlet extractor and then dried. And after sulfonating like Example 1, it washed and dried and obtained carbonaceous material.

Example 6
Iron (III) nitrate nonahydrate the _{(Fe (NO 3) 3 ·} 9H 2 O) 0.500g to obtain an aqueous solution of iron nitrate dissolved in water 100 ml. Its cobalt (II) nitrate hexahydrate solution _{(Co (NO 3) 2 ·} 6H 2 O) was added and mixed 1.5 g. To the obtained aqueous solution, 1.0 g of powdery CMC · Na (manufactured by Wako Pure Chemical Industries, Ltd., model number: 039-01335) was added and stirred to obtain a gel-like precipitate. And it dried at 65 degreeC for about 5 days using the constant temperature drying furnace until the water | moisture content of the obtained gel-like deposit was lost. Thereafter, the dried precipitate was pulverized in an agate mortar. The pulverized precipitate was transferred to a three-necked flask and heated in a nitrogen atmosphere at 250 ° C. for 1 hour in the three-necked flask to obtain a carbide.

Then, 3.000 g of the obtained carbide was put in a mixed solution of 75 ml of fuming sulfuric acid (SO ₃ concentration 20%) and 75 ml of concentrated sulfuric acid (concentration 96%), and 10 ° C. at 80 ° C. under a nitrogen atmosphere in a three-necked flask. The mixture was stirred for hours and subjected to sulfonation treatment. Thereafter, the obtained carbide was washed with 3000 ml of distilled water and dried at 105 ° C. to obtain 3.000 g of a carbonaceous material.

Example 7
Carbide was obtained in the same manner as in Example 6 except that the amount of cobalt nitrate (II) hexahydrate dissolved in the aqueous iron nitrate solution was changed to 0.5 g. Then, 1.955 g of the obtained carbide was put into a mixed solution of 75 ml of fuming sulfuric acid (SO ₃ concentration 20%) and 76 ml of concentrated sulfuric acid (concentration 96%), and 10 ° C. at 80 ° C. in a three-necked flask in a nitrogen atmosphere. The mixture was stirred for hours and subjected to sulfonation treatment. Thereafter, the obtained carbide was washed with 3000 ml of distilled water and dried at 105 ° C. to obtain 1.955 g of a carbonaceous material.

Example 8
Iron (III) nitrate nonahydrate the _{(Fe (NO 3) 3 ·} 9H 2 O) 0.500g to obtain an aqueous solution of iron nitrate dissolved in water 100 ml. Its nickel (II) nitrate hexahydrate solution _{(Ni (NO 3) 2 ·} 6H 2 O) was added and mixed 1.5 g. To the obtained aqueous solution, 1.0 g of powdery CMC · Na (manufactured by Wako Pure Chemical Industries, Ltd., model number: 039-01335) was added and stirred to obtain a gel-like precipitate. And it dried at 65 degreeC for about 5 days using the constant temperature drying furnace until the water | moisture content of the obtained gel-like deposit was lost. Thereafter, the dried precipitate was pulverized in an agate mortar. The pulverized precipitate was transferred to a three-necked flask and heated in a nitrogen atmosphere at 250 ° C. for 1 hour in the three-necked flask to obtain a carbide.

Example 9
Carbide was obtained in the same manner as in Example 8 except that the amount of nickel (II) nitrate hexahydrate dissolved in the aqueous iron nitrate solution was changed to 0.5 g. Then, 3.4168 g of the obtained carbide was put into a mixed solution of fuming sulfuric acid (SO ₃ concentration 20%) 100 ml and concentrated sulfuric acid (concentration 96%) 100 ml, and in a three-neck flask at 80 ° C. in a nitrogen atmosphere. The mixture was stirred for hours and subjected to sulfonation treatment. Thereafter, the obtained carbide was washed with 3000 ml of distilled water and dried at 105 ° C. to obtain 3.4168 g of a carbonaceous material.

[Differential scanning thermal analysis]
In Example 1, 3.554 mg of the carbide before the sulfonation treatment and 3.586 mg of the carbonaceous material after the sulfonation treatment were each measured in an air atmosphere using a differential heat / thermogravimetry apparatus (TG / DTA). Differential scanning calorimetry was performed under the temperature rising condition of ° C / min. The results are shown in FIGS. 1 and 2, respectively. As shown in FIG. 1, in the carbide before the sulfonation treatment, an exothermic peak considered to be caused by oxidative decomposition was confirmed at around 330 ° C. and 420 ° C. Further, as shown in FIG. 2, in the carbonaceous material after the sulfonation treatment, an exothermic peak considered to be caused by oxidative decomposition was confirmed at around 390 ° C. and 400 ° C. As the differential heat / thermogravimetric measuring apparatus, “TG8120” manufactured by Rigaku Corporation was used.

[SEM observation]
Using a scanning electron microscope apparatus (SEM), an electron micrograph (SEM image) was taken for each of the carbide of Example 1 before the sulfonation treatment and the carbonaceous material of Example 1 after the sulfonation treatment. FIG. 3 is an electron micrograph (SEM image) of the carbide before the sulfonation treatment, and FIG. 4 is an electron micrograph (SEM image) of the carbonaceous material after the sulfonation treatment. From the obtained photographs, all the samples were confirmed to have many holes of several nm to several tens of nm. As the scanning electron microscope apparatus, “S-3000N” manufactured by Hitachi High-Technologies Corporation was used.

[TEM observation]
Using a transmission electron microscope (TEM), the carbide of Example 1 before sulfonation, the carbonaceous material of Example 1 after sulfonation, the carbonaceous material and sulfone of Example 2 after sulfonation An electron micrograph (TEM image) was taken for each carbonaceous material of Example 5 after the chemical treatment. 5 and 6 are electron micrographs (TEM images) of the carbide of Example 1 before the sulfonation treatment. 7 and 8 are electron micrographs (TEM images) of the carbonaceous material of Example 1 after the sulfonation treatment. FIG. 9 is an electron micrograph (TEM image) of the carbonaceous material of Example 2 after sulfonation, and FIG. 10 is an electron micrograph (TEM image) of the carbonaceous material of Example 5 after sulfonation. ). From the obtained photograph, it was found that particles of about 5 to 50 nm were present in any sample. Here, when the particles were not circular, the equivalent circle diameter was taken as the diameter. As the transmission electron microscope apparatus, “EM002BF” manufactured by Topcon Techno House Co., Ltd. was used.

[Measurement of specific surface area, pore volume, pore diameter]
Using a specific surface area / pore distribution measuring apparatus, the carbonized materials of Examples 1 to 5 before sulfonation, the carbonaceous materials and sulfones of Examples 1 to 5 after sulfonation by the nitrogen adsorption method (BET method) An adsorption isotherm was measured for each of the carbides of Example 6 before the crystallization treatment. Each sample was analyzed by the BJH (Barrett, Joyner, and Halenda) method, and the average pore diameter and total pore volume were calculated. The results are summarized in Table 1. In Table 1, as the carbonaceous material of Example 1 after the sulfonation treatment, a carbonaceous material having a particle size of 150 μm or less obtained by sieving using a sieve was used.

  FIG. 11 is a pore distribution curve analyzed by the BJH method for the carbide of Example 1 before sulfonation. FIG. 12 is a pore distribution curve analyzed by the BJH method for the carbonaceous material of Example 1 after sulfonation treatment. FIG. 13 is a pore distribution curve analyzed by the BJH method for the carbide of Example 6 before the sulfonation treatment.

  Further, from the analysis by the HK (Horvath-Kawazoe Method) method, the pore widths of the carbide of Example 1 before the sulfonation treatment and the carbonaceous material of Example 1 after the sulfonation treatment were calculated. Was about 0.8 nm. FIG. 14 is a pore distribution curve obtained by analyzing the carbide before sulfonation with the HK method. FIG. 15 is a pore distribution curve obtained by analyzing the carbonaceous material after the sulfonation treatment by the HK method. As the specific surface area / pore distribution measuring apparatus, “NOVE 4200e” manufactured by Quantachrome Instruments was used.

[Analysis by powder X-ray diffraction method]
Using an X-ray diffractometer, qualitative analysis was performed on the carbide of Example 1 before sulfonation and the carbonaceous material of Example 1 after sulfonation by powder X-ray diffraction using Cu-Kα rays. . The result is shown in FIG. As shown in FIG. 16, a broad peak was confirmed when the half width (2θ) was in the vicinity of 10 to 30 °, and it was found that all the samples contained amorphous carbon in which graphene sheets were randomly assembled. As shown in FIG. 16, it can be seen that the peak at a half width (2θ) of 45 to 50 ° is derived from sodium carbonate (Na ₂ CO ₃ ), and the carbide before the sulfonation treatment is sodium carbonate (Na ₂ CO ₃ ) It was found to contain. In addition, as shown in FIG. 16, it can be seen that the broad peak having a half width (2θ) of about 10 to 30 ° is derived from iron (III) sulfate and amorphous carbon, and the carbonaceous material after sulfonation treatment is sulfuric acid. It was found to further contain iron (III). In addition, in each sample, peaks were confirmed at half-value widths (2θ) of around 30 °, 35 °, 43 °, 53 °, 57 °, and 63 °, and it was also found that magnetite (Fe ₃ O ₄ ) was contained. In addition, in each sample, peaks were confirmed at half-value widths (2θ) of around 33 °, 35 °, 40 °, and 63 °, and it was also found that maghemite (γ-Fe ₂ O ₃ ) was contained.

Using an X-ray diffractometer, qualitative analysis was performed on the carbide of Example 6 before the sulfonation treatment by powder X-ray diffraction using Cu—Kα rays. The result is shown in FIG. As shown in FIG. 17, peaks derived from cobalt oxide (Co ₃ O ₄ , CoO), maghemite (γ-Fe ₂ O ₃ ), and Fe ₃ Co ₇ were observed. Moreover, the peak derived from the simple substance of cobalt was also confirmed. As the X-ray diffractometer, “RINT 2500HF” manufactured by Rigaku Corporation was used.

Using an X-ray photoelectron spectrometer, wide scan measurement was performed on the carbide of Example 1 before sulfonation and the carbonaceous material of Example 1 after sulfonation by X-ray photoelectron spectroscopy. FIG. 18 shows the measurement results of carbide before sulfonation. FIG. 19 shows the measurement results of the carbonaceous material after the sulfonation treatment. From the obtained results, the elements detected by the wide scan measurement were C _1s (carbon), N _1s (nitrogen), O _1s (oxygen), Fe _2p (iron), and Na _1s (sodium). Further, S _2p (sulfur) was also confirmed in the carbonaceous material after the sulfonation treatment.

Moreover, the measurement by narrow scan was also performed about the carbide | carbonized_material of Example 1 before a sulfonation process, and each carbonaceous material of Example 1 after a sulfonation process. As a result, from the O _1s spectrum, a peak derived from maghemite (γ-Fe ₂ O ₃ ), a peak derived from an organic compound, a peak derived from SO ₃ and SO _4, and a peak derived from Na ₂ CO _3. Were confirmed. Furthermore, peaks derived from C—C (H), C—O, C═O, and —CO ₃ were confirmed from the C _1s spectrum. The presence of maghemite (γ-Fe ₂ O ₃ ) was confirmed from the value of the binding energy of the main peak of the Fe _2p spectrum. The presence of iron (III) sulfate (Fe ₂ (SO ₄ ) ₃ ) was confirmed in the carbonaceous material after the sulfonation treatment. Further, the carbonaceous material after the sulfonation treatment was also confirmed to have peaks derived from SO ₄ and SO ₃ H groups of iron (III) sulfate in the S _2p spectrum. The results are shown in FIGS. As the X-ray photoelectron spectrometer, “Quantera SXM” manufactured by ULVAC-PHI Co., Ltd. was used.

[Analysis by Mossbauer spectroscopy]
Using a Mossbauer spectrometer, a Mossbauer spectrum was measured for each of the carbide of Example 1 before the sulfonation treatment and the carbonaceous material of Example 1 after the sulfonation treatment by Mossbauer spectroscopy. The results are shown in FIG. As shown in FIG. 24, as a result of measurement at room temperature (293K), a broad apparent singlet peak was observed as a main peak near the center of the spectrum in all samples. A broad magnetic splitting peak was observed in the carbide before the sulfonation treatment. In the carbonaceous material after the sulfonation treatment, no magnetic splitting peak was observed, but a very broad absorption that seemed to extend the singlet peak was also observed. Each sample is greatly different from the component (γ-Fe ₂ O ₃ or Fe ₃ O ₄ ) expected to be contained from the measurement result by the powder X-ray diffraction method, and it is found that the paramagnetic component occupies most. It was. Considering from transmission electron micrographs, it was found that superparamagnetic material (particle size of 10 nm or less) was present in any sample. Moreover, in order to observe a magnetic splitting peak, it measured at liquid nitrogen temperature (78K). As a result, the magnetic splitting peak became the main component in the carbide before the sulfonation treatment. In the carbonaceous material after the sulfonation treatment, the paramagnetic component remains the paramagnetic component, but the magnetic splitting peak can be clearly seen.

The carbide before the sulfonation treatment was analyzed on the assumption that all of the peaks were due to magnetic fission. As a result, the spectrum of the carbide before the sulfonation treatment could be interpreted as a substantially single magnetic component (γ-Fe ₂ O ₃ ). The carbonaceous material after the sulfonation treatment is considered to contain iron (III) sulfate (Fe ₂ (SO ₄ ) ₃ ) in addition to γ-Fe ₂ O ₃ . The parameters of Fe ₂ (SO ₄ ) ₃ Mossbauer are IS = 0.39 mm / s, QS = 0.60 mm / s at room temperature, and show magnetic splitting of 550 kOe at 1.8 K. In addition, since the Neel point of Fe ₂ (SO ₄ ) ₃ is 30K, it is considered to be consistent with the result of this measurement because it is paramagnetic at 78K.

[Elemental analysis]
Elemental analysis by the combustion method was performed for each of the carbides of Examples 1 to 7 before the sulfonation treatment and the carbonaceous materials of Examples 1 to 5 after the sulfonation treatment (Analysis A). In addition, using the X-ray photoelectron spectrometer, quantitative analysis by narrow scan measurement was also performed on the carbide of Example 1 before sulfonation treatment and the carbonaceous material of Example 1 after sulfonation treatment (Analysis B). . The results are shown in Table 2.

[Analysis by infrared spectroscopy]
Using a Fourier transform infrared spectrometer (FT-IR), infrared spectroscopy measurement was performed on the carbide of Example 1 before sulfonation and the carbonaceous material of Example 1 after sulfonation by the KBr method. It was. The results are shown in FIG. As shown in FIG. 25, a peak due to OH bending was observed at 1595 to 1603 cm ⁻¹ . Further, the carbonaceous material after sulfonation treatment, the SO ₃ to 1041cm ^-1, a peak due to stretching of the O = S = O is confirmed respectively 1377 cm ^-1, the peak due to bending of OH to 1595～1603Cm ^-1 Was also confirmed. As the Fourier transform infrared spectrometer, “Nicolet 6700 FT-IR” manufactured by Thermo Fisher Scientific Co., Ltd. was used.

[Analysis by nuclear magnetic resonance method]
Furthermore, the structure of the carbonaceous material of Example 1 after the sulfonation treatment was determined by a nuclear magnetic resonance method using a nuclear magnetic resonance apparatus. ^{A 13} C DD / MAS (Dipolar Decoupling / Magic Angle Spinning) NMR spectrum is shown in FIG. As shown in FIG. 26, there is a peak derived from carbon having an aromatic ring near a chemical shift of 130 ppm, carbon having a sulfo group bonded to about 140 ppm, carbon having a hydroxyl group bonded to about 155 ppm, and carbon having a carboxyl group bonded to about 185 ppm. Each was observed. As a result, it was found that the carbonaceous material after the sulfonation treatment has aromatic carbon, a sulfo group (SO ₃ H group), a carboxyl group (COOH group), and a hydroxyl group (OH group). Further, since no signal appeared at 0 to 100 ppm, it was also found that sp ³ carbon was hardly contained. As the nuclear magnetic resonance apparatus, “JNM-ECX400” manufactured by JEOL Ltd. was used.

[Measurement of acid points]
Using a fully automatic temperature programmed desorption spectrometer, the acid point strength and acid point number of the carbonaceous materials of Examples 1 to 5 after sulfonation were measured by the ammonia temperature programmed desorption method. Specifically, the strength and the number of acid points of the carbonaceous material were measured according to the following procedures (pretreatment), (ammonia adsorption treatment), and (ammonia desorption treatment). As a fully automatic temperature programmed desorption spectrometer, “TPD-1-ATw” manufactured by Nippon Bell Co., Ltd. was used.

(Preprocessing)
(1) A cell was filled with 0.05 g of a carbonaceous material.
(2) While supplying helium to the cell at a flow rate of 50 mL / min, the temperature was increased to 400 ° C. at a temperature increase rate of 10 ° C./min.
(3) When the temperature in the cell reached 400 ° C., helium was left for 1 hour while supplying the helium at a flow rate of 50 mL / min while maintaining the temperature.

(Ammonia adsorption treatment)
(1) The temperature in the cell was lowered to 100 ° C. Then, while maintaining the temperature, helium containing 0.5% by volume of ammonia was supplied into the cell at a flow rate of 100 mL / min for 30 minutes.
(2) While maintaining the temperature in the cell at 100 ° C., helium was supplied at a flow rate of 50 mL / min for 30 minutes to remove ammonia in the cell.

(Ammonia desorption treatment)
(1) While supplying helium into the cell at a flow rate of 50 mL / min, the temperature was increased to 400 ° C. at a rate of temperature increase of 10 ° C./min to desorb ammonia adsorbed on the carbonaceous material. The ammonia desorbed at this time was quantified by detecting the peak of NH ₂ ⁺ (m / z = 16) using a quadrupole mass spectrometer.

  The measurement results are shown in FIG. In FIG. 27, the horizontal axis indicates the temperature during the ammonia desorption treatment, and the vertical axis indicates the ammonia desorption amount converted per carbonaceous material weight. Table 3 shows the sum of the peak temperature value and the amount of ammonia desorbed during the ammonia desorption treatment.

As control examples, the strength and the number of acid points of the carbon solid acid described in Examples of JP-A-2009-268960 were also measured. Specifically, the microcrystalline cellulose was heat-treated (carbonized) under a nitrogen gas flow, and then naturally cooled to obtain carbonized microcrystalline cellulose. Subsequently, the obtained carbonized microcrystalline cellulose was put into a mixed solution of sulfuric acid and fuming sulfuric acid, and was subjected to heat treatment (sulfonation treatment) under a nitrogen gas flow. Next, after sufficiently washing with water vapor, drying was performed to obtain a carbon solid acid of a control example. According to the NH ₃ -TPD method described above, the strength and the number of acid points of the carbon solid acid of the control example were measured. The measurement results are indicated by broken lines in FIG. Table 3 shows the sum of the peak temperature value and the amount of ammonia desorbed during the ammonia desorption treatment.

In the NH ₃ -TPD method, ammonia adsorbed at a weak acid site is desorbed at a low temperature, and ammonia adsorbed at a strong acid site is desorbed at a high temperature. That is, in Table 3, the peak temperature value indicates the strength of the acid point. The total ammonia desorption amount indicates the adsorption point of ammonia existing on the sample surface, that is, the number of acid points.

  As shown in FIG. 27 and Table 3, the strength of the acid point of the carbonaceous material after the sulfonation treatment of this example was almost the same as that of the carbon solid acid of the control example. On the other hand, the total amount of desorbed ammonia was higher for the carbonaceous material of this example than for the carbon solid acid of the control example. From this result, it was found that the carbonaceous material of this example had more acid sites than the carbon solid acid of the control example. It was also found that the number of acid points varies depending on the amount of iron nitrate dissolved in water when the carbonaceous material is synthesized. In this example, when 1.00 g of iron nitrate was dissolved in 100 ml of water to obtain a carbonaceous material (Example 4), the acid point was the highest.

[Analysis by Raman spectroscopy]
Using a Raman spectrometer, Raman measurement was performed on the carbide of Example 1 before the sulfonation treatment and the carbonaceous material of Example 1 after the sulfonation treatment. The results are shown in FIG. As shown in FIG. 28, a peak called G band around 1580 cm ^-1 is a peak called D band around 1350 cm ^-1 was confirmed, respectively. The G band is a peak caused by vibrations in the hexagonal lattice of carbon atoms, and the D band is a peak caused by carbon atoms having dangling bonds such as amorphous carbon. Therefore, the larger the intensity ratio of the D band / G band, the larger the size of the graphene sheet included in the sample. The ratio of the D band to the peak intensity of the G band was about 0.8, and based on this, it was found that the average size of the graphene sheets contained in the carbide and the carbonaceous material was both about 1 nm. As a Raman spectrometer, “T-64000” manufactured by Jobin Yvon was used.

[Measurement of magnetic properties]
Using a vibrating sample magnetometer, 11.00 mg of the carbide of Example 1 before sulfonation and 8.21 mg of the carbonaceous material of Example 1 after sulfonation were packed in an acrylic holder, and the magnetic properties were measured. did. As a result, as shown in FIG. 29, the coercive force of the carbide before the sulfonation treatment was about 100 Oe. The coercive force of the carbonaceous material after the sulfonation treatment was about 30 Oe. And it was found that almost no hysteresis was observed in any of the magnetic curves, and it was soft magnetic. The saturation magnetization of the carbide before the sulfonation treatment was about 12 emu / g, and the saturation magnetization of the carbonaceous material after the sulfonation treatment was about 6 emu / g. The magnetic properties of the carbonaceous materials of Examples 2 to 5 after the sulfonation treatment were also examined. The numerical values obtained by the measurement are shown in Table 4, and the magnetic curves are shown together in FIG. As shown in Table 4 and FIG. 30, the carbon material of Example 4 had the highest saturation magnetization value.

  A magnetic property was measured by packing 63.84 mg of the carbide of Example 6 before sulfonation in an acrylic holder. As a result, as shown in FIG. 31, the coercive force of the carbide of Example 6 before the sulfonation treatment was about 330.60 Oe, and the saturation magnetization was about 34.84 emu / g. 82.57 mg of the carbide of Example 8 before sulfonation was packed in an acrylic holder, and the magnetic properties were measured. As a result, as shown in FIG. 32, the carbonaceous material of Example 8 before the sulfonation treatment had a coercive force of about 119.30 Oe and a saturation magnetization of about 26.15 emu / g. Table 4 shows the numerical values obtained by the measurement. FIG. 33 is a summary of FIGS. 29, 31, and 32. As the vibrating sample magnetometer, “VSM-15” manufactured by Toei Kogyo Co., Ltd. was used.

  Experiments on hydrolysis (saccharification) of cellulose using the carbonaceous material of Example 1 after sulfonation as an acid catalyst were conducted. 30 mg of the carbonaceous material, 30 mg of microcrystalline cellulose (trade name Avicel (Cellulose microcrystalline for column chromatography) manufactured by MERCK), and 0.3 ml of water are sealed in a vial (manufactured by Nichiden Kagaku Glass Co., Ltd., model number: SVF-). 12 and a volume of 12 ml), and a stirring bar was put into the sealed vial.

  Then, the above-mentioned sealed vial is immersed in a silicone oil bath (manufactured by As One Co., Ltd., model number: EO-200) installed on a strong magnetic stirrer (manufactured by Tokyo Glass Instrument Co., Ltd., model number: F-205D). The cellulose was hydrolyzed at a stirring speed of 400 rpm for 3 hours. Thereafter, the amount of glucose contained in the reaction solution in the sealed vial was measured by high performance liquid chromatography (manufactured by JASCO Corporation, model number: LC-2000 plus). The results are shown in FIG. As shown in FIG. 34, it was found that microcrystalline cellulose is hydrolyzed and glucose (Glucose) is produced by using a carbonaceous material after sulfonation as a catalyst. At this time, the amount of glucose produced was 0.211 mg. Cellobiose, xylose (Xylose), levoglucosan (Levoglucosan) and formic acid (Formic acid) were also confirmed. From this result, it was found that the carbonaceous material of Example 1 after the sulfonation treatment functions as a solid acid.

  Further, the cellulose hydrolysis (saccharification) experiment using the carbonaceous material of Example 7 after the sulfonation treatment and the carbonaceous material of Example 9 after the sulfonation treatment as an acid catalyst was performed under the same conditions as described above. It was. As a result, it was found that microcrystalline cellulose was hydrolyzed and glucose (Glucose) was produced in any experiment. Therefore, it was found that both the carbonaceous material of Example 7 after the sulfonation treatment and the carbonaceous material of Example 9 after the sulfonation treatment function as a solid acid.

Claims (4)

A method for hydrolyzing cellulose using as a catalyst a solid acid comprising a carbonaceous material comprising amorphous carbon;
The amorphous carbon includes a graphene sheet;
The carbonaceous material has a sulfo group;
The ratio of sulfur atoms to carbon atoms (S / C) is 0.005 to 0.15,
In the ammonia temperature-programmed desorption method, the peak temperature is in the range of 175 to 200 ° C., and the acid point determined from the amount of ammonia desorbed at 100 to 400 ° C. is 30 μmol / g or more,
The total pore volume determined by the BJH method is 0.02 to 1 cm ³ / g, the average pore diameter is 2 to 30 nm, and the total ratio of metal atoms to carbon atoms (Metal / C) is 0. A method for hydrolyzing cellulose, which is 5 or less . A method for hydrolyzing cellulose using as a catalyst a solid acid comprising a carbonaceous material comprising amorphous carbon;
The amorphous carbon includes a graphene sheet;
The carbonaceous material has a sulfo group;
The ratio of sulfur atoms to carbon atoms (S / C) is 0.005 to 0.15,
In the ammonia temperature-programmed desorption method, the peak temperature is in the range of 175 to 200 ° C., and the acid point determined from the amount of ammonia desorbed at 100 to 400 ° C. is 30 μmol / g or more,
Metal oxide particles are dispersed in the amorphous carbon matrix, and the total ratio of metal atoms to carbon atoms (Metal / C) is 0.001 to 0.5. Method for hydrolysis of cellulose. The method for hydrolyzing cellulose according to claim 2, wherein the carbonaceous material has a coercive force of 500 Oe or less and a saturation magnetization of 0.1 emu / g or more . The method for hydrolyzing cellulose according to any one of claims 1 to 3, wherein a ratio of hydrogen atoms to carbon atoms (H / C) in the carbonaceous material is less than 1 .

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