JP2011241104A - Method for producing nanocarbon, multiporous composite metal oxide for producing nanocarbon and apparatus for producing nanocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing high quality nanocarbon in a large amount and at low cost.SOLUTION: The nanocarbon can be more inexpensively produced using a catalyst-assisted chemical vapor deposition method by continuously feeding a multiporous composite metal oxide and a hydrocarbon gas from a hopper 25 for feeding a catalyst to a screw conveyor 22 as a reaction tube placed in an electric oven 21 having a catalyst-activating zone 21a heated at 400-1,000°C, a nanocarbon-synthesizing zone 21b and a cooling zone 21c, and continuously taking out the synthesized nanocarbon from a discharge hopper 26. According to the invention, the method and an apparatus for producing the high quality nanocarbon in a large amount at low cost are obtained. In addition, the nanocarbon can be produced at lower cost, as energy can be recovered by effectively using the hydrogen gas generated in the nanocarbon synthesizing zone for power generation by a fuel cell 28b.

Description

  The present invention relates to a method for continuously producing a large amount, low cost, and high quality nanocarbon efficiently, a porous composite metal oxide for the production of the continuous nanocarbon, and a continuous nanocarbon. It relates to a manufacturing apparatus.

  Nanocarbon includes carbon black, nanocarbon fiber, carbon nanotube, multi-walled carbon nanotube (MWCNT), cup stack tube, carbon nanohorn and the like. These nanocarbons have various excellent physical properties such as chemical stability, high electron conductivity, high electron emission ability, and high elastic modulus. Nanocarbons are expected to be used in various applications such as field emission electron-emitting devices, probes for scanning probe microscopes, catalysts, structural reinforcement materials, battery electrodes, and sensor materials using the physical properties described above. ing.

  As a method for producing these nanocarbons, an arc discharge method, a laser evaporation method, a chemical vapor deposition method and the like are known. As one of mass production methods of carbon nanotubes, a fluid catalytic method is known. The fluid catalyst method is a method in which raw material hydrocarbons such as benzene and toluene in which catalyst fine particles are dispersed are sent together with hydrogen to a reactor heated to about 1000 ° C. and reacted to obtain MWCNT. On the other hand, carbon black is used for fillers, pigments, etc., and is produced by instantly carbonizing raw material hydrocarbons at a high temperature of 300-1800 ° C. for a few ms to form black fine particles having a diameter of 7-500 nm. Is done. As the manufacturing method, furnace method, channel method, acetylene method, thermal method, lamp method and the like are used.

  For example, Patent Document 1 below relates to the invention of “Method and Apparatus for Producing Carbon Nanotubes” and uses a chemical vapor deposition method (CVD method) that is easy to operate, and the efficiency of a solid catalyst and a carbon-containing compound at 500 to 1200 ° C. In order to make good contact, the reaction tube installed in the heating furnace is rotated to stir the solid catalyst, and the solid catalyst can be uniformly contacted with the solid catalyst and the carbon-containing compound. And an example in which carbon nanotubes can be produced more efficiently by using a device that continuously supplies raw material carbon-containing compounds and continuously extracts the generated carbon nanotubes.

  An apparatus 80 for producing carbon nanotubes disclosed in the following Patent Document 1 includes a cylindrical reaction tube 81 that rotates around an axis that is slightly inclined with respect to the horizontal or horizontal, for example, as shown in FIG. Was maintained at a predetermined temperature in the heating furnace 82, and before or after the reaction tube 81, a supply port 84 for introducing a solid catalyst with a screw pump 83, a supply port 85 for introducing a carbon-containing compound, and carbon nanotubes adhered. A product take-out port 86 for taking out the solid catalyst and an exhaust port 87 are provided. According to the apparatus 80 for producing the carbon nanotube, the solid catalyst and the carbon-containing compound can be continuously supplied into the reaction tube 81, and the solid catalyst is agitated by rotating the reaction tube 81, thereby improving the efficiency. It is an apparatus that can be produced well and that can continuously mass-produce carbon nanotubes.

  In Patent Document 1 below, the solid catalyst may be any catalyst as long as the catalyst metal is supported on the surface of the solid support. The solid support may be either an organic substance or an inorganic substance. Inorganic materials are preferable, and silica, alumina, magnesium oxide, titanium oxide, silicate, diatomaceous earth, aluminosilicate, layered compound, zeolite, activated carbon, graphite, etc. can be used as the inorganic solid support, among which catalytic metals It is indicated that an inorganic porous material that can be uniformly supported is preferable, and that among zeolites, zeolite is preferable in that the pore diameter and the skeleton composition are uniform.

  Patent Document 2 below relates to the invention of “a continuous production method and production apparatus for carbon nanotubes”, and uses a chemical vapor deposition method (CVD method) that is easy to operate, and a carbon-containing compound and a solid catalyst held on a carrier device. The carbon nanotube is produced by bringing the solid catalyst held in the conveying device into contact with the carbon-containing compound in the temperature zone heated to 500 to 940 ° C. in the heating furnace to produce carbon nanotubes. In the figure, carbon nanotubes held by the transfer device that has passed through the container are continuously collected.

  An apparatus 90 for producing carbon nanotubes shown in the following Patent Document 2 is provided with an endless belt type belt conveyor as a conveying apparatus 91 as shown in FIG. 13, for example, and contains carbon before or after the solid catalyst heating furnace 92. A supply port 93 for introducing a compound and an exhaust port 94 are provided, and an inert gas curtain 95 is provided as a function for preventing the inflow of the atmospheric gas, so that the inflow of the atmospheric gas into the heating furnace 92 can be prevented. A supply port 96 for introducing a solid catalyst is provided in front of the furnace 92, and the solid catalyst is held in advance in a container 97 and conveyed to the heating furnace 92. As a result, the carbon-containing compound can be supplied to the solid catalyst held in the transport device 91. The transfer device 91 is provided with, for example, three temperature regions that can be independently controlled: a temperature rising region 92a, a reaction region 92b, and a cooling region 92c, and the temperature range of the heating furnace 92 is also the temperature rising region 92a and reaction region 92b. The cooling area 92c can be controlled independently.

  The solid catalyst used in the invention shown in the following Patent Document 2 is not particularly limited as long as the catalyst metal is supported on the surface of the solid support, and the solid support may be organic or inorganic. In view of the above, an inorganic substance is preferable, and as an inorganic solid support, silica, alumina, magnesium oxide, titanium oxide, silicate, diatomaceous earth, aluminosilicate, layered compound, zeolite, activated carbon, graphite, etc. can be used, It has been shown that an inorganic porous body capable of uniformly supporting the catalyst metal is preferable, and that the zeolite is preferable in that the pore diameter and the skeleton composition are uniform among the inorganic porous bodies.

  Zeolite is a crystalline inorganic oxide having a pore size of molecular size, and the molecular size generally means a range of about 0.2 to 2 nm, crystalline silicate, crystalline It is a crystalline microporous material composed of aluminosilicate, crystalline metallosilicate, crystalline aluminophosphate, crystalline metalloaluminophosphate, or the like.

Further, Patent Document 3 below relates to the invention of “Method for mass production of multi-walled carbon nanotubes”, in which an unreduced and unsupported precursor of a supported metal catalyst is used in situ for the catalyst. Process for selective mass production of multi-walled carbon nanotubes from catalytic cracking of hydrocarbons, comprising reducing in situ under conditions that allow for production in water and production of said nanotubes, and recovering the resulting nanotubes The invention is disclosed. The unsupported precursor used here is a Co _x Mg _{(1-x) 2} O solid solution, and the hydrocarbon is acetylene gas diluted with a carrier gas.

  Patent Document 4 listed below relates to the invention of “Catalyst for Vapor Deposition Method Carbon Fiber Production and Method for Producing Carbon Fiber”, and at least a water-soluble Group 8 metal compound as a catalyst for carbon fiber production by the vapor phase growth method. A catalyst for vapor phase growth carbon fiber production containing a group 8 metal oxide, which is obtained by firing a mixture containing an organic compound, wherein the amorphous group 8 metal oxide in the group 8 metal oxide is 10 An example is shown in which the weight ratio is 85% by weight or more and the crystalline metal oxide in the total metal oxide is 85% by weight or less.

  In this case, the molar ratio between the Group 8 metal compound and the metal compound other than Group 8 may be 10 mol% or more, particularly 15 mol% or more, particularly 20 with respect to the total metal equivalent. The upper limit is preferably 50 mol% or less, more preferably 40 mol% or less. In addition, the “carbon fiber” in the invention disclosed in the following Patent Document 4 means a carbon fiber called a carbon nanofiber (carbon nanotube) having a diameter of 1 μm or less.

  On the other hand, hydrogen gas is a basic raw material used in the production of basic chemicals and is an important form of primary energy. Currently, most of industrial hydrogen gas is produced by a steam reforming method or a partial oxidation method from a carbonaceous raw material such as naphtha or natural gas. For example, in the steam reforming method, a relatively light hydrocarbon raw material such as naphtha grade light oil, natural gas (methane), and refined petroleum offgas (methane, propane, butane) is used at a high temperature of 5 to 20 atmospheres and 700 to 850 ° C. The catalyst is reacted with water vapor on the catalyst to generate a synthesis gas which is a mixture of carbon monoxide, carbon dioxide and hydrogen. In the partial oxidation method, hydrocarbon is reacted with oxygen or air and water vapor at normal pressure to 50 atm and about 1300 ° C. to generate synthesis gas which is a mixture of hydrogen and carbon monoxide.

  In recent years, a method has been developed for obtaining hydrogen gas together with nanocarbon by bringing a hydrocarbon feedstock into contact with a catalyst at a high temperature. For example, Patent Document 5 below relates to the invention of “use of a method for producing hydrogen” and relates to hydrogen gas and nanocarbon by bringing a hydrocarbon-containing supply gas supplied into contact with a catalyst in a reformer at a gas station. A method is shown in which the produced hydrogen gas is stored and shipped to consumers for distribution. Here, hytan (for example, natural gas or methane) is used as the hydrocarbon raw material, and at least one selected from Group VIII transition elements, preferably Fe, Ni, Co, and Mo, as the catalyst, and alkaline earth metal oxidation And a composite catalyst containing at least one selected from silicon, silicon oxide.

In the invention as shown in Patent Document 5, Co containing SiO _2, Ni and Fe catalyst, or Ni, a powder of a hydroxide or oxide containing Fe and Ni / Fe is water, an alcohol, Obtained by precipitating SiO ₂ "on" a metal hydroxide dispersed in acetone or any other suitable solvent. SiO ₂ is deposited directly on the hydroxide by adding a base (eg, NH ₃ / H ₂ O) to decompose tetraoxysilane (TEOS). In a further form, substoichiometric SiO ₂ —Ni (OH) ₂ , SiO ₂ —Fe (OH) _3, or SiO ₂ —Ni / Fe hydroxide can be directly or simultaneously added to the base. Is obtained in one step by precipitation. Even in that case, it should be noted that the main component of the composite catalyst is a Group VIII transition metal, which is at least in a proportion exceeding 50 mol%, preferably exceeding 80 mol%, more preferably exceeding 90 mol%. Exists.

  This catalyst is exposed to a reducing atmosphere before use, and only the transition metal component is reduced to a metal. This composite catalyst is first led to the preheating zone, heated to an operating temperature of 500 to 1000 ° C. in the heating zone, the feed gas is decomposed into hydrogen gas and nanocarbon, and then cooled in the cooling zone. Since the obtained gas contains not only hydrogen gas but also undecomposed hydrocarbon gas, the hydrogen gas is separated by a PSA plant or the like and used for use as necessary. .

JP 2003-252613 A JP 2003-238125 A JP 2003-206117 A JP 2006-181477 A Special table 2009-513466 gazette

  According to the inventions disclosed in Patent Documents 1 and 2 above, it is possible to produce a large amount of carbon nanotubes continuously. However, the solid catalyst is obtained by previously supporting a catalyst metal on a solid support. Yes. In the case where such a catalytic metal is previously supported on a solid support, the catalytic metal changes with the passage of time after the production of the solid catalyst, so that it is difficult to produce carbon nanotubes with stable physical properties and the yield is not stable. There is. In addition, the catalytic activity of the solid catalyst increases as the amount of the catalytic metal increases, but it is difficult to uniformly support a large amount of metal, and the catalytic activity decreases when the catalytic metals overlap. For this reason, the amount of catalyst metal supported is usually about 10% by mass, and only about 20% by mass at most can be supported, making it difficult to increase the yield.

  Further, according to the invention shown in the above-mentioned Patent Document 3, as a catalyst, a metal catalyst that has not been previously reduced and that is not supported and an acetylene gas is used. Since reduction and multi-walled carbon nanotube formation are performed simultaneously, pre-reduction in the gas phase or addition of hydrogen is not required for unsupported precursors, and multi-walled carbon nanotubes are selected at low temperatures It is said that there is an effect that it can be produced in large quantities.

However, Patent Document 3 only shows an example using acetylene as a hydrocarbon raw material, and magnesium nitrate hexahydrate (10 mmol), cobalt nitrate hexahydrate (6 mmol), and citric acid are used as catalysts. Only examples using a Co _0.4 Mg _0.6 O solid solution prepared by calcination at 700 ° C. for 5 hours under nitrogen flow using an acid (10 mmol) are shown, and the calcination is performed during the preparation of the catalyst. It has been shown that catalytic activity does not occur when run in. Furthermore, Patent Document 3 does not disclose anything about whether other hydrocarbon raw materials or catalysts having other compositions can be used, and for producing a large number of multi-walled carbon nanotubes. No specific manufacturing apparatus configuration is shown.

  In addition, according to the invention disclosed in Patent Document 4 above, as a catalyst, the amorphous group 8 metal oxide in the group 8 metal oxide is 10% by weight or more, and the crystalline metal oxide in the total metal oxide is used. An example in which the product is 85% by weight or less is shown, and the molar ratio between the group 8 metal compound and the metal compound other than group 8 is that of the group 8 metal relative to the total amount in terms of metal. It is said that it is preferably 50 mol% or less, particularly 40 mol% or less. This catalyst is used after being previously activated in a reducing atmosphere or in contact with a carbon fiber raw material gas together with a reducing gas. However, the above-mentioned Patent Document 4 does not show any specific configuration of a manufacturing apparatus for producing carbon fiber.

In the invention disclosed in Patent Document 5, the catalyst is sequentially transferred to a preheating section, a heating section, and a cooling section, first led to the preheating section, and then heated to an operating temperature of 500 to 1000 ° C. in the heating section. As a result, the supply gas is decomposed into hydrogen gas and nanocarbon, so that nanocarbon can be continuously produced in large quantities, and hydrogen gas can be supplied to consumers. However, since the composite catalyst used in the invention disclosed in Patent Document 5 is exposed to a reducing atmosphere before use and only the transition metal component is reduced to metal, the above-mentioned Patent Documents 1 and 2 are used. The same problem as that of the invention shown in FIG. Further, the form of a composite catalyst as shown in Patent Document 5 manufacturing cost since separating the catalyst particles is increased by SiO ₂ particles produced by expensive TEOS in the case of SiO _2. Further, there is a problem that a dangerous chemical such as hydrogen fluoride must be used to separate the synthesized nanocarbon and the composite catalyst.

  The present invention has been made to solve the above-described problems of the prior art, and is an efficient method for continuously producing a large amount, low cost, and high quality nanocarbon. An object of the present invention is to provide a porous composite metal oxide for production and an apparatus for producing continuous nanocarbon.

  The above object of the present invention can be achieved by the following configurations. That is, the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method according to the present invention comprises a porous composite metal oxidation in a reaction tube installed in a furnace having a catalyst activation zone, a nanocarbon synthesis zone and a cooling zone. In the catalyst activation zone, an active catalyst body in which a part of the porous composite metal oxide is metalized with a hydrocarbon gas or a separately supplied reducing gas is obtained in the catalyst activation zone. It is characterized by continuously synthesizing nanocarbon by contacting hydrocarbon gas and active catalyst in the carbon synthesis zone, and taking out the resulting composite of nanocarbon and active catalyst from the reaction tube through the cooling zone. To do.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, a porous composite metal oxide is used as a material before obtaining an activated catalyst. The porous composite metal oxide is not a material on which the catalyst is supported on the surface of the carrier like the conventional catalyst, but is a homogeneous compound. Moreover, since the porous composite metal oxide is a chemically stable compound, it is difficult to deteriorate even if it is stored after production.

  In the continuous nanocarbon production method by the catalyst-assisted chemical vapor deposition method of the present invention, a hydrocarbon gas or a reducing gas separately supplied in the catalyst activation zone for the porous composite metal oxide. Thus, an active catalyst body in which a part of the porous composite metal oxide is metallized is obtained and brought into contact with the hydrocarbon gas and the active catalyst body in the nanocarbon synthesis zone. When such a configuration is adopted, the active catalyst body in which a part of the porous composite metal oxide obtained in the catalyst activation zone is metallized is immediately converted into a hydrocarbon gas in the nanocarbon synthesis zone with good catalytic activity. Therefore, the composite of nanocarbon and active catalyst can be synthesized with high efficiency. In addition, from the composite of nanocarbon obtained by the continuous nanocarbon production method by the catalyst-assisted chemical vapor deposition method of the present invention and the active catalyst body, the nanocarbon can be easily prepared in the same manner as in the conventional example. Carbon can be separated.

  Moreover, in the continuous nanocarbon production method by the catalyst-assisted chemical vapor deposition method of the present invention, the porous composite metal oxidation is performed in a reaction tube installed in a furnace having a catalyst activation zone, a nanocarbon synthesis zone, and a cooling zone. Since the nanocarbon is generated by continuously supplying the product and the hydrocarbon gas, it is possible to obtain a very high purity hydrogen gas in the nanocarbon synthesis zone, and by effectively using this hydrogen gas, Cost reduction can be achieved. In addition, since the catalyst activation zone can be made at a lower temperature than the nanocarbon synthesis zone, it is difficult for the carbon to be formed as a by-product in the catalyst activation zone, and moreover, nanocarbon is generated intensively in the nanocarbon synthesis zone. Therefore, a composite of high quality nanocarbon and an active catalyst can be continuously produced.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the porous composite metal oxide is at least one first type selected from magnesium, calcium, strontium, and barium. A porous composite metal oxide composed of an oxide of the metal and an oxide of at least one second metal selected from manganese, iron, cobalt, nickel, copper, molybdenum, and tungsten, The content ratio of the second type metal oxide is preferably 50 to 95% by mass with respect to the total mass of the porous composite metal oxide.

  The oxide of the first type metal in the porous composite metal oxide used in the present invention is difficult to be reduced by a hydrocarbon gas or a reducing gas, but the oxide of the second type metal is a hydrocarbon gas. In addition, the second metal that is easily reduced to a metal by reduction with a reducing gas is well known as a catalyst for producing nanocarbon. Therefore, according to the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the reduced second type metal superoxide while maintaining the porosity by the first type metal oxide. Since the fine particles are isolated, the catalyst for nanocarbon production having good catalytic activity is obtained.

  In this case, as the porous composite metal oxide, a water-soluble compound of at least one first metal selected from magnesium, calcium, strontium, and barium, and manganese, iron, cobalt, nickel, copper, molybdenum, tungsten A water-soluble compound of at least one second metal selected from the group consisting of tartaric acid, cysteine, arginine, glycine, alanine and leucine, an organic compound having a melting point of 200 ° C. to 300 ° C., and water. What was mixed and produced by baking at 400 to 700 degreeC in the air can be used.

  The porous composite metal oxide used in the present invention comprises a water-soluble compound of a first type metal, a water-soluble compound of a second type metal, an organic compound having a melting point of 200 ° C. to 300 ° C., water Are mixed and fired in air at 400 ° C. to 700 ° C., so that the organic compound contains a water-soluble compound of the first type metal and a water-soluble compound of the second type metal. Since it is burned, gasified and foamed, a porous composite metal oxide can be easily obtained. If the melting point of the organic compound is less than 200 ° C., it evaporates before foaming and good porosity cannot be obtained, and if the melting point exceeds 300 ° C., carbon remains after firing, which is not preferable. Furthermore, when the firing temperature is 400 ° C. or lower, the carbon component of the organic compound raw material remains, and when it is 700 ° C. or higher, the oxide crystal grains become coarse. More preferably, it is 500 degreeC-700 degreeC.

Further, in the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the porous composite metal oxide is a porous sintered body of particles having a particle diameter of 10 to 200 nm, It is preferable to use one having a bulk density of 0.05 to 0.5 g / cm ³ and a BET specific surface area of 5 to 100 m ² / g.

When the porous composite metal oxide used in the present invention has the above-mentioned physical properties, it is easy to handle, and a composite of high-quality nanocarbon and an active catalyst is easily formed. It becomes possible to manufacture continuously. In addition, it is difficult to stably produce a porous composite metal oxide having a particle size of 10 nm or less, and a particle size of 200 nm or more is not preferable because large-sized nanocarbon is synthesized. The particle size of the porous composite metal oxide is more preferably 20 nm to 80 nm. For the same reason, the BET specific surface area is preferably 10 to 50 m ² / g.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the hydrocarbon gas is selected from methane, ethane, ethylene, acetylene, propane, propylene, isoprene, and n-butane. At least one kind can be used.

  According to the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, since a wide range of materials can be used as the raw material hydrocarbon gas, the range of design is widened.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the hydrocarbon gas is preferably supplied from the cooling zone to the nanocarbon synthesis zone. Moreover, it is preferable to add water vapor | steam or a humid reducing gas with the said hydrocarbon gas.

  According to the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, when the hydrocarbon gas is supplied from the cooling zone to the nanocarbon synthesis zone, the active catalyst and the generated nanocarbon are produced in the cooling zone. Since heat can be recovered from the carbon and the hydrocarbon gas can be preheated, the thermal efficiency is improved, and in the nanocarbon synthesis zone, the reaction proceeds rapidly when it comes into contact with the active catalyst, so that side reactions are unlikely to occur. A composite of high quality nanocarbon and an active catalyst can be continuously produced. In addition, if the process is managed so that the reaction is completed in the nanocarbon synthesis zone controlled at an appropriate temperature, nanocarbon is not synthesized in the cooling zone, and a high purity hydrogen atmosphere is created in the catalyst activation zone. A catalyst for producing nanocarbon having good catalytic activity is obtained from the porous composite metal oxide. Furthermore, by adding water vapor or humid reducing gas together with the hydrocarbon gas, it works to suppress the formation of amorphous carbon and has the effect of extending the life of the catalyst activity.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the catalyst activation zone and the nanocarbon synthesis zone are heated to 500 to 1000 ° C., and the pressure in the reaction tube is 0. It is preferable to be in the range of 1 to 10 kPa.

  The temperature range of the catalyst activation zone is preferably not less than the temperature at which part of the porous composite metal oxide is metallized and not more than the temperature of the nanocarbon synthesis zone. The temperature of the nanocarbon synthesis zone is not less than the temperature at which hydrocarbons are thermally decomposed and not more than the maximum temperature at which nanocarbon is preferentially synthesized on the catalyst. When the pressure in the reaction tube is limited as described above, side reactions are less likely to occur, and a complex of high-quality nanocarbon and an active catalyst can be continuously produced.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the separately supplied reducing gas may be hydrogen gas, ammonia gas, or hydrogen produced in the nanocarbon synthesis zone. It is preferable to use gas.

  When the reducing gas supplied to the catalyst activation zone is hydrogen gas, ammonia gas, or hydrogen gas generated in the nanocarbon synthesis zone, the catalyst activation zone has nano catalyst with good catalytic activity from the porous composite metal oxide. Since it becomes a catalyst for carbon production, it becomes possible to continuously produce higher quality nanocarbon and active catalyst composites.

  Further, in the continuous nanocarbon production method by the catalyst-assisted chemical vapor deposition method of the present invention, the gas components of the catalyst activation zone, the nanocarbon synthesis zone and the cooling zone in the reaction tube are analyzed, It is preferable that the hydrogen gas concentration in the catalyst activation zone is 80% or more by controlling the flow rate of the hydrocarbon gas.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, by analyzing the gas components in the catalyst activation zone, the nanocarbon synthesis zone, and the cooling zone, an appropriate hydrocarbon gas flow rate is obtained. If the process is controlled so that the reaction is terminated in the nanocarbon synthesis zone by controlling, the nanocarbon is not synthesized in the cooling zone, and the atmosphere of high purity hydrogen is formed in the catalyst activation zone, resulting in porous composite metal oxidation. It becomes a catalyst for producing nanocarbon having good catalytic activity from the product. In the catalyst activation zone, the lower the hydrocarbon concentration and the higher the hydrogen concentration, the smaller the amount of by-produced nanocarbons, so that higher quality nanocarbon and active catalyst composites can be produced continuously. become. The analysis of the gas component is preferably performed on hydrocarbon gas, hydrogen gas, and water vapor.

In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the bulk density of the composite of the obtained nanocarbon and the active catalyst is 0.05 to 0.5 g / It is preferable to be cm ³ .

In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, it depends on the bulk density of the porous composite metal oxide and the stirring conditions at the time of synthesis, but at 0.05 g / cm ³ or less, The yield is poor due to scattering during the synthesis, and the uniformity of synthesis is insufficient at 0.5 g / cm ³ or more. By setting the bulk density of the resulting composite of nanocarbon and active catalyst within the above-mentioned numerical range, it is possible to continuously produce a composite of higher quality nanocarbon and active catalyst. become.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the reaction tube is a screw conveyor, a rotary kiln, or a belt conveyor arranged in a tubular body, and the porous composite It is preferable to continuously produce a composite of the nanocarbon and the active catalyst while moving the metal oxide in the order of the catalyst activation zone, the nanocarbon synthesis zone, and the cooling zone.

  By using a screw conveyor, a rotary kiln or a belt conveyor arranged in a tubular body, the porous composite metal oxide is brought into contact with a predetermined reaction gas while being sequentially stirred and moved in the catalyst activation zone, nanocarbon synthesis zone and cooling zone. Therefore, a composite of the nanocarbon and the active catalyst can be continuously produced.

  In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the nanocarbon may be carbon black, nanofiber, multi-wall nanotube, or cup stack tube.

In the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, the hydrogen gas generated in the nanocarbon synthesis zone is at least one selected from a fuel cell, a turbine, and an engine. It is preferable to use it for power generation.

  According to the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method of the present invention, very high purity hydrogen gas can be obtained in the nanocarbon synthesis zone, and this hydrogen gas can be used for power generation. As a result, it is possible to achieve a reduction in cost when producing a composite of nanocarbon and an active catalyst.

  Furthermore, the porous composite metal oxide of the present invention is a porous composite metal oxide for use in the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method described above, An oxide of at least one first metal selected from magnesium, calcium, strontium, barium and at least one second metal selected from manganese, iron, cobalt, nickel, copper, molybdenum, tungsten. An oxide, and the content ratio of the oxide of the second type metal is 50 to 95% by mass with respect to the total mass of the porous complex metal oxide. It is a range.

  The oxide of the first type metal in the porous composite metal oxide of the present invention is hardly reduced by a hydrocarbon gas or a reducing gas, but the oxide of the second type metal is a hydrocarbon gas or a reducing gas. The second type of metal that is easily reduced to a metal by the above-described method is well known as a catalyst for producing nanocarbon. Therefore, according to the porous composite metal oxide of the present invention, while maintaining the porosity by the oxide of the first type metal, the reduced second type metal exists on the surface thereof, A catalyst for producing nanocarbon having good catalytic activity can be obtained.

In the porous composite metal oxide of the present invention, the porous composite metal oxide is a porous sintered body of particles having a particle diameter of 10 to 200 nm and has a bulk density of 0.05 to 0.00. It is preferably 5 g / cm ³ and a BET specific surface area of 5 to 100 m ² / g.

  As the porous composite metal oxide of the present invention, if it has the above-mentioned physical properties, it is easy to handle and easily produces a composite of high-quality nanocarbon and active catalyst continuously. It becomes a porous composite metal oxide that can be made.

  Furthermore, the continuous nanocarbon production apparatus using the catalyst-assisted chemical vapor deposition method of the present invention includes a furnace capable of individually controlling the temperature of each of the catalyst activation zone, the nanocarbon synthesis zone, and the cooling zone, A reaction tube installed across the catalyst activation zone, the nanocarbon synthesis zone and the cooling zone, and means for continuously supplying porous composite metal oxide particles to the catalyst activation zone in the reaction tube And means for transferring the porous composite metal oxide particles from the catalyst activation zone in the reaction tube to the outside of the reaction tube through the nanocarbon synthesis zone and the cooling zone, and the cooling zone in the reaction tube Means for supplying a hydrocarbon gas or a mixed gas of a hydrocarbon gas and a reducing gas disposed on the side, and the porous composite of the catalyst activation zone. Characterized in that it comprises a recovery means of gases disposed in means side for supplying the metal oxide particles.

  Further, in the continuous nanocarbon production apparatus by the catalyst-assisted chemical vapor deposition method of the present invention, means for supplying a reducing gas to the nanocarbon synthesis zone side of the catalyst activation zone in the reaction tube is further provided. Is preferably formed.

  In the continuous nanocarbon production apparatus using the catalyst-assisted chemical vapor deposition method of the present invention, the reaction tube is preferably a screw conveyor or a rotary kiln.

  In the continuous nanocarbon production apparatus using the catalyst-assisted chemical vapor deposition method of the present invention, a belt conveyor may be disposed inside the reaction tube.

  Further, in the continuous nanocarbon production apparatus according to the catalyst-assisted chemical vapor deposition method of the present invention, the gas recovery means includes a fuel cell, a turbine to which a generator is connected, and an engine to which the generator is connected. It may be connected to at least one selected.

  According to the continuous nanocarbon production apparatus by the catalyst-assisted chemical vapor deposition method of the present invention, the continuous nanocarbon production method by the catalyst-assisted chemical vapor deposition method of the present invention can be easily carried out. become able to.

It is the schematic of the nanocarbon manufacturing apparatus used in Examples 1-19 and Comparative Examples 1-12. It is a graph showing the temperature change in the reaction tube of FIG. FIG. 10 is a schematic view of a screw conveyor type nanocarbon production apparatus used in Example 20. 4 is an image observed by FE-SEM of the porous composite metal oxide obtained in Example 20. FIG. It is the schematic of the nanocarbon manufacturing apparatus of the combined system of the rotary kiln and the screw conveyor used in Example 21. 2 is an image observed by FE-SEM of the porous composite metal oxide obtained in Example 21. FIG. 2 is an image observed by FE-SEM of a composite of nanocarbon and an active catalyst obtained in Example 21. FIG. It is the image which changed the magnification of FIG. FIG. 6 is an image observed by a transmission electron microscope of cup-stacked nanocarbon separated in Example 21. FIG. FIG. 10 is a schematic view of a belt conveyor type nanocarbon manufacturing apparatus used in Example 22. FIG. 12 is a block diagram of a nanocarbon production apparatus of Example 23. It is the schematic of the apparatus which manufactures the conventional carbon nanotube. It is the schematic of the apparatus which manufactures another conventional carbon nanotube.

  Hereinafter, the form for implementing this invention using various Examples and a comparative example is demonstrated. However, the examples shown below are a method for producing continuous nanocarbon by a catalyst-assisted chemical vapor deposition method, a porous composite metal oxide, and a catalyst-assisted chemical vapor phase to embody the technical idea of the present invention. It is intended to exemplify an apparatus for producing continuous nanocarbon by a growth method, and is not intended to limit the present invention to this embodiment, and the present invention departs from the technical idea shown in the claims. The present invention can be equally applied to various modifications without any change.

[Examples 1 to 19 and Comparative Examples 1 to 12]
[Production of porous composite metal oxides]
Using magnesium nitrate, calcium nitrate, strontium nitrate as the water-soluble compound of the first type metal, nickel nitrate, ferric nitrate, cobalt nitrate, and ammonium molybdate as the water-soluble compound of the second type metal, The mixing ratio is variously changed corresponding to Examples 1 to 19 and Comparative Examples 1 to 12, and the organic compound is a composition that is 100 g of 25 mass% L-alanine and 19 mass% ion-exchanged water. Mix and stir with a magnetic stirrer. This composition was transferred to a stainless steel container and placed in a firing furnace maintained at 700 ° C. After 16 minutes, a ceramic composite porous metal oxide was obtained. This was pulverized to obtain a porous composite metal oxide for producing nanocarbons corresponding to Examples 1 to 19 and Comparative Examples 1 to 12 by using 400 μm mesh-passed powder. The composition of the obtained porous composite metal oxide is summarized in Table 1.

[Production of nanocarbon]
First, the nanocarbon production efficiency of the porous composite metal oxide corresponding to each of Examples 1 to 19 and Comparative Examples 1 to 12 was confirmed using the nanocarbon production apparatus shown in FIG. In the nanocarbon production apparatus 10, a quartz glass tube having a diameter of 40 mm as a reaction tube 12 is disposed in an electric furnace 11, and a stainless steel rotating drum container 13 having a diameter of 35 mm is disposed in the reaction tube 12. . The electric furnace 11 is controlled to a predetermined temperature by a program temperature control device 14, and the rotating drum container 13a is rotated at a predetermined rotational speed by a motor 13b.

  Here, 0.2 g of porous composite metal oxide powder 16 having a composition corresponding to each of Examples 1 to 19 and Comparative Examples 1 to 12 is inserted into a stainless steel rotating drum container 13a, and the motor 13b is used. The rotary drum container 13a was rotated at a rotation speed of 2 rpm, and the porous composite metal oxide powder 16 was stirred. Then, in order to reproduce the temperature history of the catalyst activation zone, the nanocarbon synthesis zone, and the cooling zone, the temperature in the reaction tube 12 is changed with time by the program temperature controller 14 as shown in FIG. In the time zone corresponding to the activation zone, the temperature is raised from 200 ° C. to 700 ° C. over 30 minutes, and in the time zone corresponding to the nanocarbon synthesis zone, it is maintained in the temperature range of 700 ° C. ± 10 ° C. for 30 minutes. In the corresponding time zone, the temperature was lowered from 700 ° C. to 300 ° C. over 10 minutes.

  In the time zone corresponding to the catalyst activation zone, a reducing gas (nitrogen-5% hydrogen) 18 is passed through the humidifier 19 to generate an active catalyst body in which a part of the porous composite metal oxide is metallized. did. Next, when the temperature reached 700 ° C. ± 10 ° C., the reducing gas 18 was replaced with a propane gas which is a hydrocarbon gas 17. The flow rates of the reducing gas 18 and the hydrocarbon gas 17 were adjusted so that the pressure was about 1 kPa while measuring the pressure in the reaction tube 12 with the pressure gauge 15. At this time, nanocarbon is synthesized around the active catalyst body, and at the same time, hydrogen gas is generated. After synthesizing nanocarbon for 30 minutes, the hydrocarbon gas was switched to the nitrogen-5% hydrogen mixed gas in the time zone corresponding to the cooling zone.

  When the temperature of the rotating drum container 13a becomes 200 ° C. or lower, the sample in the rotating drum container 13a is taken out into the atmosphere, and the active catalyst bodies corresponding to Examples 1 to 19 and Comparative Examples 1 to 12 are The total mass of the composite in which nanocarbon was synthesized was measured. The thus measured “(mass of nanocarbon composite) / (mass of composite metal oxide)” is shown together with the composition of the porous composite metal oxide in Table 1. In Table 1, “(mass of nanocarbon composite) / (mass of composite metal oxide)” is (mass of nanocarbon composite) = (mass of active catalyst body + mass of nanocarbon). The numerical value substantially corresponds to the synthesis rate (yield) of nanocarbon.

  From the results shown in Table 1, the following can be understood. That is, in any case of Comparative Examples 1-4 and Examples 1-5, Comparative Examples 5-8, Examples 6-10, Comparative Examples 9-12, and Examples 11-15, the second type metal The yield of nanocarbon increases as the oxide content increases, and particularly when the content of the second metal oxide is 50% by mass or more, the second metal oxide. The yield of nanocarbon is significantly increased as compared with the case where the content ratio of is 40% by mass or less. However, when the content ratio of the second metal oxide exceeds 80% by mass, the yield of nanocarbon slightly decreases. Such a tendency is the case where the second type metal is nickel or iron, and even when the first type metal is magnesium or calcium. Shows a similar trend.

  Also, the composite metal oxide of Example 16 in which the second type metal is nickel and iron, the composite metal oxide of Example 17 in which nickel and cobalt are also used, and the composite metal oxide in Example 18 in which nickel and molybdenum are also used. In addition, the composite metal oxide of Example 19 in which the second type metal is nickel and the first type metal is strontium oxide (SrO) has a content ratio of the second type metal of 60% by mass. From the above, the yield of nanocarbon is as high as 15 or more.

Of these, magnesium oxide (MgO), calcium oxide (CaO), and strontium oxide (SrO), which are oxides of the first type metal, are not reduced by reducing gas such as hydrogen gas at 700 ° C. It is clear that it exists as it is. In addition, nickel oxide (NiO), iron oxide (FeO), cobalt oxide (CoO), and molybdenum trioxide (MoO ₃ ), which are oxides of the second type of metal, can be easily obtained by reducing gas such as hydrogen gas at 700 ° C. It is clear that they are present as the corresponding metals.

  Therefore, considering the composition of the known nanocarbon production catalyst, the first type metal is selected from magnesium, calcium, strontium, and barium conventionally used as a support for the catalyst for nanocarbon production. At least one can be used, and the second metal is selected from manganese, iron, cobalt, nickel, copper, molybdenum, and tungsten, which are conventionally used as metal catalysts for producing nanocarbons. It can be seen that at least one can be used. Note that both the first type metal and the second type metal may be water-soluble salts in order to facilitate the production of the porous composite metal oxide.

  For example, as the water-soluble salt of the first type metal, for example, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate or the like can be used. Further, as the water-soluble salt of the second type metal, manganese chloride, ferric nitrate, cobalt nitrate, nickel nitrate, copper sulfate, 6 ammonium molybdate, ammonium tungstate, and the like can be used.

  Moreover, although the example which used L-alanine as an organic compound was shown here, since this organic compound is a substance which lose | disappears in the case of baking and contributes to the porosity of a composite metal oxide, it has a similar physical property. An organic compound, for example, one or more selected from tartaric acid, cysteine, arginine, glycine, alanine, and leucine and having a melting point of 200 ° C. to 300 ° C. may be used. If the melting point of the organic compound is less than 200 ° C., a composite metal oxide having good porosity cannot be obtained, and if the melting point exceeds 300 ° C., carbon remains in the composite metal oxide after firing, which is not preferable.

  As an example of hydrocarbon gas, propane was used here, but not only propane but also methane, ethane, ethylene, acetylene, propylene, isoprene, which are commonly used as raw materials for producing nanocarbons. N-butane or the like can be used. When using a hydrocarbon gas other than propane, the temperature of the catalyst activation zone and the nanocarbon synthesis zone is appropriately selected within 500 to 1000 ° C. according to the thermal decomposition temperature of each hydrocarbon, In order to smoothly advance the reaction in which the hydrocarbon gas is converted into nanocarbon and hydrogen gas around the active catalyst body, the pressure in the reaction tube may be controlled in the range of 0.1 to 10 kPa.

The porous composite metal oxide is preferably produced by firing in the air at 400 to 700 ° C. When the firing temperature is 400 ° C. or lower, the carbon component of the raw material remains in the composite metal oxide, and when it is 700 ° C. or higher, the crystal grains of the composite metal oxide are coarsened. A more preferable firing temperature is 500 ° C to 700 ° C. The porous composite metal oxide is a porous sintered body having a particle diameter of 10 to 200 nm, a bulk density of 0.05 to 0.5 g / cm ³ , and a BET specific surface area of 5 to 100 m ² /. It is preferable that it is g. It is difficult to stably produce a porous composite metal oxide having a particle size of 10 nm or less, and a large-sized nanocarbon is synthesized with a porous composite metal oxide having a particle size of 200 nm or more. The particle size of the porous composite metal oxide is more preferably 20 nm to 80 nm. For the same reason, the BET specific surface area is more preferably 10 to 50 m ² / g.

  In view of mass synthesis of nanocarbon, the synthesis rate (nanocarbon composite / complex metal oxide) is preferably 5 or more. In the method disclosed in the above-described prior art, the proportion of the catalyst metal is preferably 40% or less with respect to the entire catalyst particles composed of the catalyst metal and the catalyst carrier. On the other hand, as shown in Table 1, according to the present invention, in the content range of the oxide of the second metal of 50 to 95 mass% with respect to the composite metal oxide, the synthesis rate (nanocarbon composite Body / complex metal oxide) is achieved.

In addition, it is estimated that the reason why large-scale synthesis of nanocarbon can be realized as described above is as follows.
(1) The catalyst used is a porous composite metal oxide prepared by firing in air a mixture of a water-soluble compound of the first type metal, a water-soluble compound of the second type metal, an organic compound and water. thing.
(2) In the catalyst activation zone, an active catalyst body in which ultrafine particles of catalyst metal are produced is produced by reducing and metalizing the oxide of the second type of the porous composite metal oxide. thing.
(3) The produced active catalyst body is transported to the nanocarbon synthesis zone, and comes into contact with the hydrocarbon gas supplied in opposition, so that nanocarbon grows around the active catalyst body with the catalyst metal ultrafine particles at the head. thing.
In this way, nanocarbon grows around the active catalyst body with the catalyst metal ultrafine particles at the head, thereby producing a composite of nanocarbon and active catalyst body having a bulk density of 0.05 to 0.5 g / cm ^3. Is done. As a result, the nanocarbon was not scattered during the synthesis, and the mass production of the nanocarbon became possible while ensuring safety and hygiene.

[Example 20]
As Example 20, a screw conveyor system was adopted as a large-scale mass production apparatus using a catalyst-assisted chemical vapor deposition method. The screw conveyor type nanocarbon production apparatus used in Example 20 is shown in FIG. In this screw conveyor type nanocarbon manufacturing apparatus 20, a screw conveyor 22 is arranged in an electric furnace 21. The screw conveyor 22 is rotated at a predetermined constant speed by a motor 23. The electric furnace 21 is controlled by the temperature control device 24 so as to have a predetermined temperature for each of the catalyst activation zone 21a, the nanocarbon synthesis zone 21b, and the cooling zone 21c along the length direction of the screw conveyor 22. Has been.

  A catalyst supply hopper 25 made of porous composite metal oxide is disposed at the inlet end 22a of the screw conveyor 22, and a discharge hopper 26 of a composite of nanocarbon and active catalyst is disposed at the outlet end 22b. Is arranged. The outlet end 22b of the screw conveyor 22 is connected to a hydrocarbon gas supply pipe 27a, a reducing gas supply pipe 27b, and a steam or humidified reducing gas supply pipe 27d, and also connected to the inlet end 22a. An exhaust gas pipe 27c is connected to the catalyst supply hopper 25, and this exhaust gas pipe 27c is connected to a known fuel cell system 28b using hydrogen gas as fuel through a hydrogen recovery system 28a. Here, illustration of various valves is omitted (hereinafter, the same applies to other embodiments). Further, various sensing means 29 are appropriately provided to measure the temperature, gas concentration and pressure in the screw conveyor 22. Normally, the temperature and gas concentration are measured in the catalyst activation zone 21a, the nanocarbon synthesis zone 21b, and the cooling zone 21c, and the pressure is measured in the cooling zone 21c.

[Production of porous composite metal oxides]
In Example 20, a porous composite metal oxide used as a catalyst was produced as follows. First, 6% by mass of calcium nitrate as the water-soluble compound of the first type metal, 44% by mass of iron nitrate as the water-soluble compound of the second type of metal, 25% by mass of alanine as the organic compound, and 19% by mass % Ion exchanged water was mixed at a ratio of 100 g and stirred with a magnetic stirrer. This composition was transferred to a stainless steel container and placed in a firing furnace maintained at 750 ° C. in an air atmosphere. After 16 minutes, a ceramic composite porous metal oxide was obtained. This powder was pulverized and passed through a mesh of 400 μm and used as a porous composite metal oxide for producing nanocarbon. The image observed by the field emission scanning electron microscope (FE-SEM) of the porous composite metal oxide used in Example 20 thus produced is shown in FIG.

[Manufacturing preparation process]
In the nanocarbon production apparatus 20 of Example 20, the temperature was controlled so that the temperature of the nanocarbon synthesis zone 21b of the electric furnace 21 was 750 ° C. ± 5 ° C. by the temperature controller 24. At this time, the inside of the screw conveyor 22 was replaced with an inert gas, nitrogen gas, until the oxygen concentration became 1% or less.

[Supply of porous composite metal oxide]
The porous composite metal oxide powder produced as described above was supplied from the catalyst supply hopper 25 to the inlet end 22a of the screw conveyor 22 at a constant and constant speed of 50 g / hr. At this time, a nitrogen-5% hydrogen mixed gas, which is a reducing gas, was supplied from the outlet end 22 b of the screw conveyor 22 to the screw conveyor 22 from the reducing gas supply pipe 27 b. Thereby, an active catalyst body in which a part of FeO of the FeO—CaO porous body, which is a porous composite metal oxide, is metallized is generated at least in the catalyst activation zone 21a.

[Synthesis of nanocarbon]
Next, it is confirmed that the powder of the porous composite metal oxide has come near the outlet end 22b of the screw conveyor 22, and nitrogen-5% hydrogen which is a reducing gas flowing from the reducing gas supply pipe 27b. The mixed gas was switched to the hydrocarbon gas supply pipe 27a, and methane gas as hydrocarbon gas was allowed to flow. Further, the pressure in the screw conveyor 22 was set in a range of 0.1 to 10 kPa so that the reaction smoothly progressed around the active catalyst body. At this time, the steam or the humid reducing gas may be added to the methane gas from the steam or the humid reducing gas supply pipe 27d.

  As a result, the active catalyst body generated in the catalyst activation zone 21a is conveyed to the nanocarbon synthesis zone 21b while moving by the screw conveyor 22, and comes into contact with methane gas, which is a hydrocarbon gas supplied in opposition. Nanocarbon is synthesized around the active catalyst body, and hydrogen gas is generated at the same time. The residence time of the composite of nanocarbon and active catalyst in the nanocarbon synthesis zone 21b is set to 30 minutes.

  During the nanocarbon synthesis, the concentration of methane, hydrogen, and water vapor in the catalyst activation zone 21a, nanocarbon synthesis zone 21b, and cooling zone 21c is analyzed, and the flow rate of methane gas as hydrocarbon gas is controlled. The hydrogen gas concentration in the gasification zone 21a was controlled to be 80% or more. As a result, in the catalyst activation zone 21a, an active catalyst body in which part of FeO of the FeO-CaO porous body, which is a porous composite metal oxide, is metallized continuously by hydrogen gas generated during nanocarbon synthesis. Is done.

[Nanocarbon and hydrogen gas emissions]
The composite in which nanocarbon is synthesized on the active catalyst is accumulated in the discharge hopper 26 via the cooling zone 21c while moving by the screw conveyor 22. On the other hand, the generated hydrogen gas and water vapor are guided to the hydrogen recovery system 28a, where the hydrogen is separated and further effectively used in the fuel cell system 28b.

  The discharge rate of the composite of nanocarbon and active catalyst produced in Example 20 was 600 g / hr. As a result of observing the structure of the synthesized nanocarbon with a transmission electron microscope, it was a multi-layered parallel type nanotube.

[Example 21]
As Example 21, a combined use of a rotary kiln and a screw conveyor was adopted as a large-scale mass production apparatus using a catalyst-assisted chemical vapor deposition method. The nanocarbon manufacturing apparatus used in Example 21 will be described with reference to FIG. In the nanocarbon manufacturing apparatus 30 that employs the combined use of the rotary kiln and screw conveyor, a rotary kiln 32 is disposed in an electric furnace 31. The rotary kiln 32 is rotated at a predetermined constant speed by a motor (not shown). The electric furnace 31 is controlled by the temperature control device 34 so as to have a predetermined temperature for each of the catalyst activation zone 31a, the nanocarbon synthesis zone 31b, and the cooling zone 31c along the length direction of the rotary kiln 32. ing.

  A dust collection hopper 32c is provided at the inlet end 32a of the rotary kiln 32, and a discharge hopper 36 of a composite of nanocarbon and active catalyst is disposed at the outlet end 32b. A screw conveyor 33 is disposed from the inlet end 32a of the rotary kiln 32 to the catalyst activation zone 31a. A catalyst supply hopper 35 made of a porous composite metal oxide is disposed at an inlet end 33 a of the screw conveyor 33, and an outlet end 33 b is opened in the rotary kiln 32.

  A hydrocarbon gas supply pipe 37 a and an inert gas supply pipe 37 b (here, an inert gas supply pipe 37 b is connected to the hydrocarbon gas supply pipe 37 a are connected to the outlet end 32 b of the rotary kiln 32. And an exhaust gas pipe 37c is connected to the dust recovery hopper 32c connected to the inlet end 32a. A reducing gas or inert gas supply pipe 37d is connected to the outlet end 33b of the screw conveyor 33, and an exhaust gas pipe 37e is connected to the catalyst supply hopper 35 disposed at the inlet end 33a. The exhaust gas pipes 37c and 37e are both connected to a well-known fuel cell system 38b using hydrogen gas as fuel through a hydrogen recovery system 38a. Furthermore, various sensing means 39 are provided as appropriate to measure the temperature, gas concentration and pressure in the rotary kiln 32.

  The diameter of the rotary kiln 32 is 150 mm, and the lengths of the catalyst activation zone 31a, the nanocarbon synthesis zone 31b, and the cooling zone 31c are 250 mm, 200 mm, and 250 mm, respectively. The operating conditions of the rotary kiln 32 and the screw conveyor 33 were selected so that the holding ratio occupied by the composite was 10% and the synthesis amount was 0.2 kg / hr.

[Production of porous composite metal oxides]
In Example 21, a porous composite metal oxide used as a catalyst was produced as follows. First, 8% by mass of magnesium nitrate as the water-soluble compound of the first type metal, 42% by mass of nickel nitrate as the water-soluble compound of the second type of metal, 55% by mass of glycine as the organic compound, and 19% by mass % Ion exchanged water was mixed at a ratio of 100 g and stirred with a magnetic stirrer. This composition was transferred to a stainless steel container and placed in a firing furnace maintained at 670 ° C. in an air atmosphere. After 16 minutes, a ceramic composite porous metal oxide was obtained. This powder was pulverized and passed through a mesh of 400 μm and used as the porous composite metal oxide for producing nanocarbon of Example 21. The image observed by FE-SEM of the porous composite metal oxide thus obtained is shown in FIG.

[Manufacturing preparation process]
In the nanocarbon production apparatus 30 of Example 21, the temperature was controlled so that the temperature of the nanocarbon synthesis zone 31b of the electric furnace 31 was 670 ° C. ± 5 ° C. by the temperature controller 34. At this time, the inert gas nitrogen gas is supplied to the inside of the rotary kiln 32 and the screw conveyor 33 from the inert gas supply pipe 37b and the reducing gas or inert gas supply pipe 37d to 1% or less. Substitution was performed until the oxygen concentration reached.

[Supply of porous composite metal oxide]
The porous composite metal oxide powder produced as described above was supplied from the catalyst supply hopper 35 to the inlet end 33a of the screw conveyor 33 at a constant and constant speed of 12 g / hr. At this time, the reducing gas supply pipe 37b supplies the reducing gas nitrogen-5% mixed gas through the reducing gas or inert gas supply pipe 37d to the screw conveyor 33 from the outlet end 33b of the screw conveyor 33. did. Thereby, an active catalyst body in which a part of NiO of the NiO-MgO porous body, which is a porous composite metal oxide, is metallized is generated at least in the catalyst activation zone 31a.

[Synthesis of nanocarbon]
Next, after confirming that the powder of the porous composite metal oxide has come to the vicinity of the outlet end 33b of the screw conveyor 33, the hydrocarbon gas is replaced with the inert gas supplied from the inert gas supply pipe 37b. The butane gas, which is a hydrocarbon gas, was supplied from the supply pipe 37a at a rate of 110 L / hr so as to face the supply direction of the active catalyst body. The pressure in the rotary kiln 32 was set to a range of 0.1 to 10 kPa so that the reaction smoothly progressed around the butane gas active catalyst body. At this time, the steam or the humid reducing gas may be added to the butane gas from the steam or the humid reducing gas supply pipe 37f.

  Thereby, the active catalyst body generated in the catalyst activation zone 31a is conveyed to the nanocarbon synthesis zone 31b while moving by the rotary kiln 32, and comes into contact with butane gas which is a hydrocarbon gas supplied in an opposing manner. Nanocarbon is synthesized around the active catalyst body, and at the same time, hydrogen gas is generated at a rate of 540 L / hr. The residence time of the composite of nanocarbon and active catalyst in the nanocarbon synthesis zone 31b is set to 30 minutes.

  During the nanocarbon synthesis, the concentration of methane, hydrogen, and water vapor in the catalyst activation zone 31a, the nanocarbon synthesis zone 31b, and the cooling zone 31c is analyzed, and the flow rate of methane gas as the hydrocarbon gas is controlled, thereby increasing the catalyst activity. The hydrogen gas concentration in the gasification zone 31a was controlled to be 80% or more. As a result, in the catalyst activation zone 31a, an active catalyst body in which part of FeO of the FeO-CaO porous body, which is a porous composite metal oxide, is metallized continuously by hydrogen gas generated during nanocarbon synthesis. Is done.

[Nanocarbon and hydrogen gas emissions]
The composite in which nanocarbon is synthesized on the active catalyst is accumulated in the discharge hopper 36 by the rotary kiln 32 through the cooling zone 31c while moving. On the other hand, the generated hydrogen gas and water vapor are led to the hydrogen recovery system 38a, where the hydrogen is separated and further effectively used in the fuel cell system 38b. Images observed by the FE-SEM in which the magnification of the composite of the nanocarbon thus obtained and the active catalyst body was changed are shown in FIG. 7 and FIG.

  The discharge rate of the composite of nanocarbon and active catalyst produced in Example 21 was 0.25 kg / hr. As a result of continuous operation for 24 hours a day for 15 days, 89 kg of a composite was obtained. As a result of observing the structure of the synthesized nanocarbon with a transmission electron microscope, it was a cup-stacked nanotube as shown in FIG.

[Example 22]
As Example 22, a belt conveyor system was adopted as a large-scale mass production apparatus using a catalyst-assisted chemical vapor deposition method. The nanocarbon production apparatus used in Example 22 will be described with reference to FIG. In the nanocarbon manufacturing apparatus 40 employing this belt conveyor system, a belt conveyor 43 is disposed in a reaction tube 42 disposed in an electric furnace 41. The belt conveyor 43 is driven at a predetermined constant speed by a motor (not shown). The electric furnace 41 is controlled by the temperature controller 44 so that the catalyst activation zone 41a, the nanocarbon synthesis zone 41b, and the cooling zone 41c are individually set at predetermined temperatures along the length of the reaction tube 42. Has been.

  A catalyst supply hopper 45 is provided on the belt conveyor 43 on the inlet end 42a side of the reaction tube 42, and on the outlet end 42b side, a discharge hopper 46 for the composite of nanocarbon and active catalyst together with the brush 43a. Is arranged. The outlet end 42b of the belt conveyor 43 is connected to a hydrocarbon gas supply pipe 47a, a reducing gas or inert gas supply pipe 47b, and a steam or humidified reducing gas supply pipe 47d. An exhaust gas pipe 47 c is connected to the connected catalyst supply hopper 45. These exhaust gas pipes 47c are connected to a well-known fuel cell system 48b using hydrogen gas as fuel through a hydrogen recovery system 48a. Furthermore, various sensing means 59 are provided as appropriate in order to measure the temperature, gas concentration and pressure in the belt conveyor 43.

[Production of porous composite metal oxides]
6% by weight magnesium nitrate as the water-soluble compound of the first metal, 48% by weight of cobalt nitrate as the water-soluble compound of the second metal, 25% by weight of leucine as the organic compound, and 15% by weight of It stirred with the magnetic stirrer in the ratio used as the composition of ion-exchange water 100g. This composition was transferred to a stainless steel container and placed in a firing furnace maintained at 750 ° C. A porous composite metal oxide ceramicized after 16 minutes was produced. The powder was pulverized and passed through a mesh of 400 μm to form a porous composite metal oxide for producing nanocarbon.

[Manufacturing preparation process]
Then, the temperature was controlled by the temperature controller 44 so that the temperature of the nanocarbon synthesis zone 41b of the electric furnace 41 was 750 ° C. ± 5 ° C. At this time, the inside of the reaction tube 42 was replaced by supplying an inert gas nitrogen gas from the reducing gas or inert gas supply piping 47b until the oxygen concentration became 1% or less.

[Supply of porous composite metal oxide]
The above-mentioned porous composite metal oxide powder was supplied from the catalyst supply hopper 45 onto the belt conveyor 43 on the inlet end 42a side of the reaction tube 42 at a constant and constant speed of 50 g / hr. At this time, a nitrogen-5% hydrogen mixed gas as a reducing gas was supplied from a reducing gas or inert gas supply pipe 47b. As a result, an active catalyst body in which a part of CoO of the CoO—MgO porous body, which is a porous composite metal oxide, is metalized at least in the catalyst activation zone 41a is generated.

[Synthesis of nanocarbon]
Next, after confirming that the powder of the porous composite metal oxide has come near the outlet end 42b side of the reaction tube 42, the hydrocarbon is replaced with the inert gas supplied from the inert gas supply pipe 47b. Methane gas, which is a hydrocarbon gas, was caused to flow through the gas supply pipe 47a so as to face the supply direction of the active catalyst body. Further, the pressure in the reaction tube 42 was set to a range of 0.1 to 10 kPa so that the reaction smoothly progressed around the active catalyst body of methane gas. At this time, the steam or the humid reducing gas may be added to the methane gas from the steam or the humid reducing gas supply pipe 47d.

  Thereby, the active catalyst body generated in the catalyst activation zone 41a is conveyed to the nanocarbon synthesis zone 41b while moving by the belt conveyor 43, and comes into contact with methane gas, which is a hydrocarbon gas supplied in opposition. Nanocarbon is synthesized around the active catalyst body, and hydrogen gas is generated at the same time. The residence time of the composite of nanocarbon and active catalyst in the nanocarbon synthesis zone 41b is set to 30 minutes.

  During the nanocarbon synthesis, the concentration of methane, hydrogen and water vapor in the catalyst activation zone 41a, the nanocarbon synthesis zone 41b and the cooling zone 41c is analyzed, and the flow rate of methane gas as the hydrocarbon gas is controlled. The hydrogen gas concentration in the gasification zone 41a was controlled to be 80% or more. Thereby, in the catalyst activation zone 41a, an active catalyst body in which a part of CoO of the CoO-MgO porous body, which is a porous composite metal oxide, is metallized continuously by hydrogen gas generated during nanocarbon synthesis. Is done.

[Nanocarbon and hydrogen gas emissions]
The composite in which nanocarbon is synthesized on the active catalyst is moved by the belt conveyor 43 to the outlet end 42b side of the reaction tube 42 via the cooling zone 41c while moving, and is removed from the belt conveyor 43 by the brush 43a. It is scraped off and accumulated in the discharge hopper 46. On the other hand, the generated hydrogen gas and water vapor are guided to the hydrogen recovery system 48a, where the hydrogen is separated and further effectively used in the fuel cell system 48b.

  The discharge rate of the composite of nanocarbon and active catalyst produced in Example 22 was 600 g / hr. As a result of observing the structure of the synthesized nanocarbon with a transmission electron microscope, it was a multi-walled parallel nanotube.

[Example 23]
In the large-scale mass production apparatuses 20, 30, and 40 using the catalyst-assisted chemical vapor deposition method shown in Examples 20 to 22, energy is recovered by using the generated hydrogen gas in a fuel cell and recovering it as electric power. In this example, nanocarbon can be produced at low cost. However, in order to mass-produce nanocarbon, not only a large amount of hydrogen gas but also a large amount of unreacted hydrocarbon and waste heat are recovered. Therefore, in Example 23, using FIG. 11, catalyst-assisted chemistry capable of producing nanocarbon at a lower cost by utilizing such generated hydrogen gas, unreacted hydrocarbon and waste heat. A large-scale mass production apparatus 50 using a chemical vapor deposition method will be described.

  A large-scale mass production apparatus 50 using the catalyst-assisted chemical vapor deposition method of Example 23 includes a nanocarbon generation unit 51 and a utilization unit 70 for the generated hydrogen gas, unreacted hydrocarbons, waste heat, and the like. ing. The nanocarbon generation unit 51 includes a reaction path 52 for synthesizing nanocarbon, a porous composite metal oxide system 53 for synthesizing and supplying a porous composite metal oxide, a reducing gas and water vapor or a humidified reducing gas supply system. 54, an inert gas and hydrocarbon gas supply system 55, a nanocarbon recovery system 56 for recovering the composite of the generated nanocarbon and the active catalyst, and nanocarbon from the composite of the nanocarbon and the active catalyst Separating nanocarbon quality improvement system 57, nanocarbon storage system 58 for storing separated nanocarbon, and various sensing means 59 for detecting temperature, gas concentration and pressure in reaction path 52, and these And a control system 60 for controlling the operation of each means. In addition, since each structure of the nanocarbon production | generation part 51 is the same as that of the case of the large-scale mass-production apparatuses 20, 30, and 40 using the catalyst-assisted chemical vapor deposition method shown in Examples 20-22, the details The detailed explanation is omitted.

  The nanocarbon generation unit 51 further includes a hydrogen gas / byproduct gas switching unit 61 for switching between hydrogen gas and byproduct gas and sending them to the utilization unit 70. The gas containing high-concentration hydrogen supplied from the hydrogen gas / by-product gas switching unit 61 to the utilization unit 70 such as unreacted hydrocarbons and waste heat passes through a hydrogen gas recovery system 62a such as PSA, for example. The hydrogen gas is separated, the solid content is removed by a filter system 62b such as a bag filter, a part thereof is highly purified by a hydrogen purification system 62c using, for example, palladium, and the remaining part is directly microgas. Power supplied to the turbine system 63 and supplied to power generation is converted into AC power 63b by the power conversion system 63a and used as power for various devices.

  Further, the highly purified hydrogenated hydrogen gas is supplied to the fuel electrode of the fuel cell system 64, and the electric power generated in the fuel cell system 64 is converted into AC power 64b by the power conversion system 64a, and the power of various devices. The heat generated in the fuel cell system 64 is recovered by exchanging heat with water by the waste heat recovery system 64c, and the hot water or steam obtained by the waste heat recovery system 64c is stored in the hot water storage tank 64d. It is stored and used for various purposes in the form of warm water or water vapor 64e. The fuel cell system 64 is also provided with an air supply system 64f for supplying oxygen to the air electrode.

  In addition, components including hydrocarbon gas supplied to the utilization unit 70 such as unreacted hydrocarbons and waste heat supplied from the hydrogen gas / by-product gas switching unit 61 are concentrated in the exhaust gas recovery system 65. After that, it is burned in the exhaust gas combustion system 65a, and the heat generated at this time is supplied to the nanocarbon generator 51 and used as, for example, a preheating system 66 for firing the porous composite metal oxide. The control system 60 is also used to control various means of the utilization unit 70 such as unreacted hydrocarbons and waste heat. Thus, according to the large-scale mass production apparatus 50 using the catalyst-assisted chemical vapor deposition method of Example 23, the generated hydrogen gas, unreacted hydrocarbons and waste heat are also used to further reduce the mass production apparatus 50. Nanocarbon can be produced at low cost.

  DESCRIPTION OF SYMBOLS 10, 20, 30, 40 ... Nanocarbon production apparatus 11 ... Electric furnace 12 ... Reaction tube 13a ... Rotary drum container 13b ... Motor 14 ... Program temperature controller 15 ... Pressure gauge 16 ... Porous composite metal oxide powder 21, 31, 41 ... Electric furnace 21a, 31a, 41a ... Catalyst activation zone 21b, 31b, 41b ... Nanocarbon synthesis zone 21c, 31c, 41c ... Cooling zone 24, 34, 44 ... Temperature controller 29, 39, 49 ... Various sensing methods

Claims (20)

In a continuous nanocarbon production method by catalyst-assisted chemical vapor deposition,
A porous composite metal oxide and a hydrocarbon gas are continuously supplied into a reaction tube installed in a furnace having a catalyst activation zone, a nanocarbon synthesis zone, and a cooling zone. In the catalyst activation zone, the hydrocarbon gas Alternatively, an active catalyst body in which a part of the porous composite metal oxide is metalized by a reducing gas supplied separately is obtained, and the hydrocarbon gas and the active catalyst body are brought into contact with each other in the nanocarbon synthesis zone to form nanocarbon. And a composite of the obtained nanocarbon and the active catalyst is taken out from the reaction tube through the cooling zone, and the continuous nanocarbon is obtained by a catalyst-assisted chemical vapor deposition method. Production method. As the porous composite metal oxide,
An oxide of at least one first metal selected from magnesium, calcium, strontium, barium;
An oxide of at least one second metal selected from manganese, iron, cobalt, nickel, copper, molybdenum, tungsten;
A porous composite metal oxide composed of
2. The catalyst according to claim 1, wherein the content ratio of the oxide of the second metal is in the range of 50 to 95 mass% with respect to the total mass of the porous composite metal oxide. Continuous nanocarbon production method by assisted chemical vapor deposition. As the porous composite metal oxide,
A water-soluble compound of at least one first metal selected from magnesium, calcium, strontium, barium;
A water-soluble compound of at least one second metal selected from manganese, iron, cobalt, nickel, copper, molybdenum, tungsten;
One or more organic compounds of tartaric acid, cysteine, arginine, glycine, alanine, leucine with a melting point of 200 ° C. to 300 ° C.,
water and,
The method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method according to claim 2, wherein the mixture is prepared by mixing and calcination in air at 400 ° C. to 700 ° C. The porous composite metal oxide is a porous sintered body having a particle diameter of 10 to 200 nm, a bulk density of 0.05 to 0.5 g / cm ³ , and a BET specific surface area of 5 to 100 m ² / g. The method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method according to claim 1, wherein   The catalyst-assisted chemical vapor deposition method according to claim 1, wherein the hydrocarbon gas is at least one selected from methane, ethane, ethylene, acetylene, propane, propylene, isoprene, and n-butane. A continuous method for producing nanocarbon.   The catalyst according to claim 1, wherein the hydrocarbon gas is supplied from the cooling zone to the nanocarbon synthesis zone, and water vapor or a humid reducing gas is added together with the hydrocarbon gas. Continuous nanocarbon production method by assisted chemical vapor deposition.   The catalyst-assisted chemistry according to claim 1, wherein the catalyst activation zone and the nanocarbon synthesis zone are heated to 500 to 1000 ° C so that the pressure in the reaction tube is in the range of 0.1 to 10 kPa. Of continuous nanocarbon by chemical vapor deposition.   2. The continuous gas-assisted chemical vapor deposition method according to claim 1, wherein the separately supplied reducing gas is hydrogen gas, ammonia gas, or hydrogen gas generated in the nanocarbon synthesis zone. A method for producing nanocarbon.   The gas composition of the catalyst activation zone, the nanocarbon synthesis zone and the cooling zone in the reaction tube is analyzed, and the hydrogen gas concentration in the catalyst activation zone is controlled to 80% by controlling the flow rate of the hydrocarbon gas. The method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method according to claim 1, wherein 2. The catalyst-assisted chemical vapor phase according to claim 1, wherein a bulk density of the obtained composite of nanocarbon and active catalyst is 0.05 to 0.5 g / cm ^3. A process for producing continuous nanocarbon by a growth method.   The reaction tube is composed of a screw conveyor, a rotary kiln, or a belt conveyor disposed in a tubular body, and the porous composite metal oxide is continuously moved while moving in the order of the catalyst activation zone, the nanocarbon synthesis zone, and the cooling zone. 2. The method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method according to claim 1, wherein a composite of the nanocarbon and the active catalyst is produced.   The method of claim 1, wherein the nanocarbon is carbon black, nanofiber, multi-wall nanotube, or cup stack tube.   The hydrogen gas generated in the nanocarbon synthesis zone is supplied to at least one selected from a fuel cell, a turbine, and an engine and used for power generation. Of continuous nanocarbon by the catalyst-assisted chemical vapor deposition method. A porous composite metal oxide for use in the method for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method according to any one of claims 1 to 13,
An oxide of at least one first metal selected from magnesium, calcium, strontium, barium;
An oxide of at least one second metal selected from manganese, iron, cobalt, nickel, copper, molybdenum, tungsten;
A porous composite metal oxide composed of
The content ratio of the oxide of the second type metal is in the range of 50 to 95% by mass with respect to the total mass of the porous composite metal oxide. The porous composite metal oxide is a porous sintered body having a particle diameter of 10 to 200 nm, a bulk density of 0.05 to 0.5 g / cm ³ , and a BET specific surface area of 5 to 100 m ² / g. The porous composite metal oxide according to claim 14, wherein In continuous nanocarbon production equipment by catalyst-assisted chemical vapor deposition,
Furnaces that can be individually temperature controlled for each of the catalyst activation zone, the nanocarbon synthesis zone, and the cooling zone;
A reaction tube installed across the catalyst activation zone, the nanocarbon synthesis zone and the cooling zone in the furnace;
Means for continuously supplying porous composite metal oxide particles to the catalyst activation zone in the reaction tube;
Means for transferring the porous composite metal oxide particles from the catalyst activation zone in the reaction tube to the outside of the reaction tube through the nanocarbon synthesis zone and the cooling zone;
Means for supplying a hydrocarbon gas or a mixed gas of a hydrocarbon gas and a reducing gas disposed on the cooling zone side in the reaction tube;
A gas recovery means disposed on the catalyst activation zone on the side of supplying the porous composite metal oxide particles;
An apparatus for producing continuous nanocarbon by a catalyst-assisted chemical vapor deposition method.   The catalyst-assisted chemical vapor deposition method according to claim 16, further comprising means for supplying a reducing gas to the nanocarbon synthesis zone side of the catalyst activation zone in the reaction tube. By continuous nanocarbon production equipment.   The apparatus for producing continuous nanocarbon according to claim 16, wherein the reaction tube is a screw conveyor or a rotary kiln.   The continuous nanocarbon production apparatus according to claim 16, wherein a belt conveyor is disposed in the reaction tube.   The gas recovery means is connected to at least one selected from a fuel cell, a turbine to which a generator is connected, and an engine to which a generator is connected. An apparatus for producing continuous nanocarbon by the catalyst-assisted chemical vapor deposition method described in 1.