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  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
  • B01J37/0027—Powdering
  • B01J37/0045—Drying a slurry, e.g. spray drying
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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/16—Reducing
  • B01J37/18—Reducing with gases containing free hydrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
  • B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
  • B82B3/0004—Apparatus specially adapted for the manufacture or treatment of nanostructural devices or systems or methods for manufacturing the same
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  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y40/00—Manufacture or treatment of nanostructures
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  • C01—INORGANIC CHEMISTRY
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  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/158—Carbon nanotubes
  • C01B32/16—Preparation
  • C01B32/162—Preparation characterised by catalysts
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
  • D01F9/127—Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
  • D01F9/127—Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
  • D01F9/1271—Alkanes or cycloalkanes
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
  • D01F9/127—Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
  • D01F9/1273—Alkenes, alkynes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/18—Carbon
  • B01J21/185—Carbon nanotubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/74—Iron group metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
  • B01J37/0027—Powdering
  • B01J37/0036—Grinding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/009—Preparation by separation, e.g. by filtration, decantation, screening
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• the invention relates to a process for the preparation of a catalyst for the production of carbon nanotubes, the use of the catalyst for the production of
• the catalyst is based on at least two metals from the
• Carbon nanotubes are understood to mean mainly cylindrical carbon tubes with a diameter between 3 and 100 nm, the length being a multiple, at least 20 times, of the diameter. Carbon nanotubes are referred to below for brevity as "CNT.” These tubes consist of layers of ordered carbon atoms and have a different nucleus in morphology.These carbon nanotubes are also referred to as “carbon fibrils” or “hollow carbon fibers.” The described carbon nanotubes have Due to their dimensions and their special properties, they are of technical importance for the production of composite materials, with significant potential in electronics, energy and other applications.
• Carbon nanotubes are a well-known material for a long time. Although Iijima in 1991 (S. Iijima, Nature 354, 56-58, 1991) is generally referred to as the discoverer of nanotubes, these materials, especially fibrous graphite materials having multiple layers of graphite, have been known for some time. So z. B. in the 70s and early 80s, the deposition of very fine fibrous carbon from the catalytic decomposition of hydrocarbons described (GB 1469930A1, 1977 and EP 56004 A2, 1982, Tates and Baker). However, carbon filaments made from short-chain hydrocarbons are no longer characterized in terms of their diameter. The production of carbon nanotubes with diameters smaller than 100 nm is described, inter alia, also in EP 205 556 Bl or WO A 86/03455.
• CCVD Catalytic Carbon Vapor Deposition
• metals metal oxides or decomposable or reducible metal components.
• metals such as Fe, Mo, Ni, V, Mn, Sn, Co, Cu and others are mentioned in the prior art.
• the catalysts described in the prior art have the disadvantage that the expenses for the preparation of the heterogeneous catalyst are relatively high.
• sufficient dispersion of the primary crystallites contributing to growth must be ensured. This can be done, for example, as known in heterogeneous catalysis, by impregnation with comparatively low contents of active metals [Handbook of Heterogeneous Catalysis, Vol. 1, 1997, Chap. 2.2.].
• Here is ensured by the comparatively low surface concentration of catalytically active metal sufficient dispersion and thus the small diameter of the active metal cluster.
• WO 2006/050903 A2 has disclosed a process for preparing a catalyst for the production of CNT, in which the precursor compounds for the catalyst are subjected to an alkaline precipitation reaction and the catalyst is elaborately prepared further from the precipitated mixed hydroxides. Because of the numerous local parameters in the precipitates and impregnations, it is further known that scale-up of production is associated with great difficulty, so that in practice catalysts having a broad distribution of metal cluster diameters are usually obtained.
• a narrow particle diameter distribution is important in order to reproducibly obtain the desired diameter of the carbon nanomaterials in the product.
• WO 2007/093337 A2 describes the preparation of a catalyst by means of a continuous precipitation in a micromixer. Although very small metal cluster diameter or at the same time a very narrow distribution of the diameters are achieved, but the process requires complex filtration and washing steps to produce a highly active catalyst.
• a further disadvantage in the preparation of the catalysts of the prior art is that by wet-chemical preparation as precipitation or a loss of active components must be accepted. Most of the solutions are difficult to work up due to the high dilutions in which the catalytically active metals are produced.
• a complicated further problem is the shape of the resulting catalysts. Should these be used in a process in which the catalyst particles or catalyst / Kohlenstoffhanomaterialagglomerate or carbon agglomerates are moved by the flow of a fluid within the reactor or the solids content of the reactor is moved, so a defined particle size distribution is necessary, often only within narrow limits allowed a failure-prone and efficient reactor operation.
• the particle size here denotes the size of an occupied carrier or the mixture of carrier and active metals used in the reaction.
• additional process steps such as e.g. Comminution or agglomeration and classification necessary. In the latter case, the yield of catalyst from precipitation reactions can be significantly reduced. There is also a risk that impurities, e.g. from equipment or other batches affect the quality of the material.
• CNT catalysts having a defined particle size are required when using the catalysts for the reaction in a fluidized bed, a circulating fluidized bed, a moving bed, as well as for other reasons in the fixed bed (to reduce the pressure loss across the catalyst bed), in the floating reactor, Dust / cloud cloud reactor, downer or riser.
• the particle velocity and thus, as a rule, the mixing or residence time in the reactor depend on the particle diameter, therefore the narrowest possible particle size distribution is of technical advantage.
• the object of the present invention is to develop a process for the preparation of catalysts for CNT production, which avoids the disadvantages of the known processes and in particular works in an energy-efficient manner, in an efficient manner, the starting materials in catalyst preparation exploited, preferably the waste produced in the catalyst production or wastewater to be treated and thus minimized the steps in the production of the solid catalyst and in particular allows adjustment of an advantageous particle size of the catalyst.
• the recycling of such catalyst material into the production process should be possible, which does not occur, for example, in the range of the desired particle size distribution.
• the catalyst obtained should also preferably be usable in the reactor types described above, especially in moving beds such as fluidized beds.
• suitable catalysts can be prepared in an unexpectedly simple manner by spray drying or spray agglomeration from salt solutions of the active metals and support materials in predominantly or completely dissolved form.
• the present invention relates to a process for preparing a catalyst based on at least two catalytically active metals from the series: cobalt, manganese, iron, nickel and molybdenum for the production of carbon nanotubes with the steps:
• step c) optionally grinding the mixture obtained from step b) and, optionally, post-drying the mixture obtained from step b) at a temperature of 60 to 500 ° C.
• step d) if appropriate, classifying the mixture obtained from step b) or c) to obtain a granulate having a particle diameter in the range from 30 to 100 ⁇ m, preferably from 40 to 70 ⁇ m,
• step d) optionally further drying of the granules obtained from step d) at a temperature of 60 to 500 ° C.
• step f) calcination of the granules obtained from step e) in the presence of an oxygen-containing gas, in particular in the presence of air, at a temperature of 200 to 900 0 C, preferably 250 to 800 0 C, particularly preferably 300 to 700 0 C, in a Treatment time of at least 0.5 h, preferably 1 to 24 h, more preferably 2 to 16 h, with removal of the decomposition gases and obtaining the catalyst,
• step f) optionally subsequent reduction of the catalyst from step f) by means of reducing gases, in particular with hydrogen, in particular at a temperature of 250 to 750 ° C.,
• a solvent and possibly suspended particles no longer suspended are, for example, water, alcohols, low-boiling aliphatic and aromatic hydrocarbons, generally carbon-containing solvents, for example nitromethane or supercritical CO 2 . Due to the ease of use of known techniques, preference is given to alcoholic or aqueous solvents or mixtures thereof. Particularly preferred are aqueous solvents.
• Suitable precursors for the catalytically active materials and vehicles are preferably those compounds which can be dissolved in the solvent or solvent mixture used and which, after removal of the solvent, can be thermally decomposed to the corresponding catalyst compound (i.e., metal oxides).
• Suitable compounds are, for example, inorganic salts, for example: the hydroxides, carbonates, nitrates and the like, as well as oxalates or salts of the lower carboxylic acids, in particular acetates or derivatives, and organometallic compounds, e.g. Acetylacetonate, the metals cobalt, manganese, iron, molybdenum and nickel, wherein the metals may be present in any possible oxidation state.
• one or more carrier components may also be added to the solution as a non-soluble solid to obtain suspensions.
• the particle size of the solid is advantageously smaller than the particle diameter of the catalyst agglomerates obtained by the overall process.
• particulate matter from the classification in step d) ie particles whose diameter is below a specified specification range
• the particulate matter particles acting as nucleation nuclei and the overall yield being recycled by recycling the particulate matter of the method is increased.
• the maximum temperature of the gaseous mixture of drying gas discharged from the dryer used for the treatment during spray granulation or spray drying Solvent is chosen so that it does not come in the exit from the dryer to form sticky phases of the resulting in the spray granulation or spray drying solid.
• the gas inlet temperature of the drying gas for drying should be as high as possible in order to achieve the highest possible drying performance.
• the gas inlet temperature can be selected in the range 150 - 600 0 C. If no safety concerns or
• the preferred drying gas inlet temperature in the range 300-500 0 C.
• the drying gas is preferably air or inert gas, in particular nitrogen used.
• liquid wet material for example, a solution or suspension
• spray drying is a short-term drying process with a residence time of just under 1 sec 30 seconds
• the drops are usually below 500 .mu.m, in laboratory apparatus with correspondingly small residence times ⁇ 50 .mu.m.Da at least for longer spray towers with particle diameters above 100-200 ⁇ m coarse dry material can be generated, as it is known from granulation technologies speaks One also frequently uses spray granulation, but also downstream agglomeration pr ozesse, which may also be integrated in the cone area of the spray tower, possible [cf. Gehrmann et al., "Dryer”, Chem.Ing. Tech
• the atomization of the moist material can be done with so-called.
• Two-fluid nozzles which are preferably used at low throughput and to obtain small drops.
• This atomizing gas usually compressed air or nitrogen, abandoned.
• the former is usually operated with larger gas volumes up to gas throughputs of 2 kg of gas per kg wet material, in order to achieve droplet sizes below 50 microns.
• smaller gas throughputs of about 0.1 kg of gas per kg of moist material usually suffice.
• disk atomizers which are operated at a speed in the region of 20,000 rpm and peripheral speeds of 100 m / s and more. Both technologies, Two-fluid nozzle and disc, are particularly suitable for smaller droplet diameter ⁇ 100 ⁇ m. Although coarser droplets can be produced by corresponding reduction of gas quantity or speed, but a fine fraction is unavoidable. Narrower droplet distributions can usually be achieved by single-fluid nozzles in which the atomization energy is provided by increased pre-pressure of the moist material. At a pressure of approx. 5 to 20 bar, coarser drops with a diameter d 50 > 100 ⁇ m can be set.
• the single-fluid nozzle is particularly suitable for high throughputs, as it dispenses with the relatively expensive compressed gas, but is sensitive to throughput fluctuations. For large-scale use, the single-fluid nozzle seems advantageous. On the development scale, however, the two-fluid nozzles have prevailed rather.
• the residual moisture of the spray-dried product can be adjusted within certain limits, depending on the product-specific drying behavior, by the exhaust gas temperature of the dryer
• the gas inlet temperature is set as high as possible, since the temperature difference in the dryer also determines the throughput.
• the product takes during drying due to the evaporative cooling to the gas temperature significantly lower steady-state, usually from 40-100 0 C, depending on the solvent loading in the drying gas.
• the dry material then very quickly assumes the local gas temperature, so that the product leaves the dryer at approximately exhaust gas temperature. If overdrying does not need to be feared and gluing of the dry material through higher temperatures and the associated melting processes need not be feared, a higher exhaust gas temperature can be tolerated in order to temper the product at the same time. However, a corresponding reduction in throughput must be accepted. Therefore, if necessary, any necessary tempering is followed in suitable apparatuses. A use of the waste heat from the heat treatment for the drying is conceivable and can reduce the total energy consumption.
• the solid material obtained in step b) has little or no residual moisture remaining and is classified as described in step d).
• unwanted coarse material or fine material can be sorted out and fed back into the processes according to step a) or b).
• a shaping treatment is exceptionally possible in addition, for example by pressing, tableting or agglomeration of the intermediate product, if the desired shape in the subsequent CNT production process has not yet been achieved. However, this is usually not necessary. It is possible to insert further procedural steps, eg dedusting, compaction or especially drying and milling of the intermediate before classification.
• the milling and drying (optional step c)) can usually be dispensed with, since the intermediate product is usually obtained in the desired particle size from the spray-drying process after step b). Preference is given to a classification and reuse of the fraction of the intermediate product which has a size outside the desired particle size range, without additional solids treatment or shaping. In the case of fine dust (ie the proportion of particles whose diameter is below the specification limit), this reuse is possible and preferred without further treatment by recycling to the preparation of the solution (step a)); for the coarse material (ie particles whose diameter is above the specifcation limit) a comminution step before reuse will generally not be avoidable.
• step e) The optionally classified catalytically active intermediate from step c) or b) is then optionally after-dried (step e)) and then calcined (step f)).
• step f) batchwise or continuous methods can be used.
• decomposition products for example NO x
• the drying according to step e) is preferably carried out at a temperature of 150 to 300 0 C with temperature-stable catalyst intermediates which do not form adhesive phases by melting operations, and is preferably in the range 80-120 0 C in temperature-sensitive catalyst intermediates, which tend to form adhesive phases.
• the calcination temperature can be increased or decreased continuously or stepwise.
• step b) can be combined and directly spray-pyrolyzed material obtained. It may also be necessary due to the moisture levels to be set and Abreaktionsgrade to be decomposed precursors, downstream of a further calcining behind a Sprühpyrolyseteil whose waste heat can be used in the spray drying.
• the described thermal treatment (calcination according to step f)) can be carried out, for example, in fixed beds, tray ovens, fluidized beds and moving beds, rotary kilns, risers, downers, circulating systems.
• the calcination time is also dependent on the choice of the reactor and is adjusted accordingly.
• a reduction may optionally be advantageous. This can be carried out separately or in situ by adding a fluid containing a reducing agent, in particular hydrogen, in the reactors described above for step e).
• the solvent for step a) is preferably selected from at least one solvent of the series: water, alcohols, low-boiling, aliphatic and aromatic hydrocarbons, nitromethane or supercritical CO 2 , preferably water and alcohols, or possible mixtures thereof.
• the final drying e) is carried out at a temperature of 80 to 120 ° C. in order to prevent melting.
• low exhaust gas temperatures and high residual moistures must already be used for such products to avoid melting processes and the corresponding formation of sticky phases, so that after-drying is generally unavoidable.
• the drying e) is carried out at a temperature of 150 to 300 0 C to remove bound water in the form of Hydrathüllen already before calcination. This is possible if the material does not tend to stick as described above.
• the classification d) is particularly preferably carried out so that a granulate having a particle size in the range of 40 to 70 microns is obtained.
• the mean catalyst particle diameter is chosen according to the desired size of the CNT agglomerates to be produced.
• the narrowest possible particle size distribution is particularly advantageous for the use of the catalyst in a fluidized bed, since usually only a relatively narrow speed window exists in which the heavier large CNT agglomerates in the reactor are not yet defluidized and at the same time the fine catalyst particles are not upwardly out of the reactor Bed be discharged, a stationary operation of the reactor is thus possible without special repatriation measures.
• the precursor compounds are selected from hydroxides, carbonates, nitrates, oxalates or other salts of lower carboxylic acids, in particular acetates, the metals Co, Mn, Fe, Ni and Mo. More preferably, the precursor compounds comprise hydroxides, carbonates or nitrates, in particular nitrates at least of cobalt and manganese.
• precursor compounds for a catalyst support selected from the group of metal compounds of: alkaline earth metals (eg magnesium, calcium), aluminum, silicon, titanium, cerium and lanthanum are preferred Hydroxides, carbonates or nitrates of alkaline earth metals, aluminum, silicon, titanium and titanium, in step a) dissolved in the solvent and / or suspended.
• alkaline earth metals eg magnesium, calcium
• aluminum, silicon, titanium, cerium and lanthanum are preferred Hydroxides, carbonates or nitrates of alkaline earth metals, aluminum, silicon, titanium and titanium, in step a) dissolved in the solvent and / or suspended.
• the spray granulation or spray drying according to step b) is preferably carried out using a single-substance atomizing nozzle or a two-component atomizing nozzle with the addition of inert gas or air during the atomization.
• the energy required to produce the droplets (surface energy) is obtained only from the liquid which is conveyed with a high pre-pressure and a correspondingly high speed through a small nozzle opening.
• the energy required to produce the drops is not or not exclusively obtained from the liquid, but additionally, under high pressure, a gas is brought into contact with the liquid jet.
• the liquid pre-pressure can then be considerably lower than in the case of single atom atomization or completely eliminated.
• the choice of the appropriate method for a given atomization task also depends on the desired throughput rates. The exact operating parameters can usually be determined after carrying out appropriate preliminary tests, since the mutual dependencies of the parameters are complex.
• the pressure difference across the nozzle is from 5 * 10 5 to 300 * 10 5 Pa (5 to 300 bar), preferably 20 * 10 5 to 100 * 10 5 Pa (20 to 100 bar), more preferably 40 * 10 5 to 70 * 10 5 Pa (40 to 70 bar).
• this step is carried out with the addition of inert gas or air, wherein the ratio of gas mass flow to liquid mass flow is from 0.1 to 1 to 2 to 1.
• the smaller amounts of air can be achieved mainly in two-fluid nozzles with internal mixing and liquid pre-pressure and save in addition to the savings of compressed gas the risk of nozzle clogging. In two-fluid nozzles with external mixing, the risk of blockage of the nozzle is lower, but more atomizing gas must normally be used.
• An alternative further preferred method is characterized in that to remove the solvent in step b) a disc atomizer is used, which is operated at a speed of the atomizer disk in the range of 2000 to 20,000 rpm, in particular depending on the diameter of the disc, with a peripheral speed of 50 - 150m / s.
• the advantage of disk atomization is the saving of compressed gas and liquid pressure as well as a broad local distribution of the droplet spray in the spray tower with only one atomizing device.
• the invention also provides a catalyst for the production of carbon nanotubes, which is obtained from the process according to the invention.
• the catalyst material obtained by the catalyst preparation method according to the invention can in principle for the production of nanostructured, at least in one spatial direction also nanoscale carbon materials, in particular carbon nanotubes, by decomposition of carbonaceous gases or mixtures thereof at elevated temperature in the presence or absence of inert gases, that is the decomposition reaction not chemically directly involved gases are used in the described reactor types. Since the catalyst preparation process of the present invention makes available active catalytic materials for a wide range of applications, a wide range of reaction parameters, e.g.
• Reaction temperature 300 ° C-2500 ° C
• concentrations one or more carbon-containing educt gases which form nanoscale carbon materials under the selected conditions
• residence time residence time of the catalytically active material, the mixtures of catalytically active material and nanoscale carbon materials and the carbon nanotubes consisting mainly of carbon
• An admixed inert gas, hydrogen or the carbon-containing educt gas can be recycled in the process.
• the carbon-containing educt gas may be compounds with any
• Heteroatoms such as nitrogen, sulfur, included. There may be certain, in the deposition incorporation of heteroatoms into the carbon structure of the nanomaterials generating substances are separately added to the process.
• the invention relates to the process for the production of fibrous
• Carbon materials in particular of carbon nanotubes with an average single diameter of 2-60 nm and an aspect ratio length: diameter (L: D)> 10 by decomposition of hydrocarbons with and without heteroatoms, in particular C 1 - to C 5 -
• Alkane or C 2 - to C 5 alkenes on a catalyst in the presence of inert gas and optionally hydrogen at a temperature of 450 to 1200 ° C in a fixed bed or a fluidized bed, preferably a fluidized bed, as well as workup and purification of the resulting carbon nanotubes, characterized characterized in that a catalyst is used which is obtained from the catalyst preparation process according to the invention.
• the invention also relates to the use of the catalyst obtained from the catalyst preparation process according to the invention for the production of carbon nanotubes or agglomerates of carbon nanotubes.
• the carbon nanotubes obtained by the processes according to the invention consist essentially of largely concentric graphite layers with low-defect tube sections or have a herringbone or helix structure and have an unfilled or filled core.
• the carbon nanotubes are particularly preferably obtained in the form of agglomerates, the agglomerates in particular having a mean diameter in the range of 0.5 to 2 mm.
• a further preferred method is characterized in that the carbon nanotubes have an average diameter of 3 to 100 nm, preferably 3 to 80 nm, particularly preferably 5 to 25 nm.
• the carbon nanomaterials obtainable by the CNT preparation process according to the invention are suitable for use as additives in polymers, in particular for mechanical
• Carbon hemp materials can also be used as gas and energy storage material, for Coloring and used as a flame retardant. Due to the good electrical conductivity, the carbon nanomaterials produced according to the invention can be used as electrode material or for the production of conductor tracks and conductive structures. It is also possible to use the carbon nanotubes according to the invention as emitters in displays.
• the carbon nanomaterials are preferred in polymer composite materials, ceramic or metal composite materials for improving the electrical or thermal conductivity and mechanical properties, for the production of conductive coatings and composite materials, as a dye, in batteries, capacitors, displays (eg Fiat Screen Displays) or Light sources, as a field effect transistor, as a storage medium z. As for hydrogen or lithium, in membranes z. B.
• Carbon nanomaterial which was prepared using catalyst prepared according to the invention according to Example 2 (TEM: FA.
• Carbon nanomaterial which was prepared using catalyst prepared according to the invention according to Example 2 (TEM: FA.
• FIG. 3 shows a scanning electron microscope photograph of carbon nanomaterial which was produced using catalyst prepared according to the invention according to Example 3 (REM: FA, FEI SFEGSEM Sirion 100 T, method according to FIG.
• Example 2 Use of the catalyst described in Example 1 in the synthesis of carbonaceous nanomaterials in a fixed bed reactor
• the catalysts were tested in a fixed bed apparatus on a laboratory scale. For this purpose, a defined amount of catalyst from Example 1 in a heated from the outside by a heat transfer quartz tube was presented with an inner diameter of 9 mm.
• the temperature of the solid beds was controlled by a PID control of the electrically heated heat carrier.
• the temperature of the catalyst bed or of the catalyst / nanotube mixture was determined by a thermocouple surrounded by an inert quartz capillary. Feed gases and inert diluent gases were fed into the reactor via electronically controlled mass flow controllers.
• the catalyst samples were first heated in a stream of hydrogen and inert gas to the reaction temperature of 650 0 C. After reaching the reaction temperature, the educt gas ethene was switched on.
• the total volume flow was adjusted to 110 mLN min-1.
• the loading of the catalyst with the educt gases was carried out for a period of 100-120 minutes usually until complete deactivation of the catalyst. Thereafter, the amount of deposited carbon was determined by weighing. The structure and morphology of the deposited carbon was determined by means of SEM and / or TEM analyzes.
• yield (total) mcat, 0) / mCat, 0th
• Yield (total) mcat, 0) / mCat, 0th
• the yield of the catalyst prepared in Example I was 25.385 gCNT / gKAT.
• Example 3 Use of the catalyst described under Example 1 in the synthesis of carbonaceous nanomaterials in a fluidized bed
• the catalysts were tested batchwise in a pilot plant fluidized bed apparatus.
• the catalyst can be added via a lock system.
• the supply of catalyst and removal of product or product and catalyst can be carried out batchwise or quasi-continuously.
• the reactor is electrically heated and equipped with commercial mass flow controllers
• the bed temperature of the bed located in the reactor can with
• thermocouples Help of several thermocouples are measured and regulated.
• a grain fraction of 32-80 ⁇ m was produced by sieving from the material produced in Example 1.
• T 650 0 C (heating in N 2 ) and controlled during the experiment.
• the catalyst was mixed with a small amount of carbon nanotubes.
• a reactant stream of 4 LN / min of nitrogen and 36 LN / min of ethylene was adjusted and the reaction was continued until an incipient decline in the conversion was observed.
• reaction space was rendered inert and the material removed and fed new catalyst. From a total of 45 g of added catalyst so 1514 g carbon nanotubes were prepared, this corresponds to a yield of 33.64 g Carbon dioxide tubes per gram of catalyst added to the reactor.
• the carbon footprint error was less than 4%.
• gaseous by-products small amounts (selectivity in each case less than 8%) ethane and methane were detected by gas chromatography.
• the catalyst prepared by the spraying process according to the invention is distinguished from the prior art by a simple, time-saving and cost-saving preparation and a high activity of the catalyst according to the invention and by a high quality of the carbon nanotubes produced therewith.

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