Classifications

• • 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
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/03—Precipitation; Co-precipitation
  • B01J37/031—Precipitation
• • 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
  • B01J37/16—Reducing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • 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
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/158—Carbon nanotubes
  • C01B32/16—Preparation
  • C01B32/162—Preparation characterised by catalysts

Definitions

• the invention relates to a novel process for the preparation of catalysts for the production of carbon nanotubes in agglomerated form, which are characterized by a low bulk density.
• the catalytically active centers are present in clusters in addition to the non-active LDH or spinel structures. At most, a small amount of Co (Fe, Ni) ( ⁇ 5%) is connected to the AI (Interface). High reduction temperatures, especially in hydrogen, therefore only accelerate the sintering of the supported Co clusters (Fe, Ni clusters), leading to thicker CNTs and further reduced activity, provided that the Co cluster size (Fe, Ni) is the maximum for CNT Synthesis exceeds suitable size.
• WO 86/003455 A1 discloses that the supported catalysts described there are not or only slightly active despite hydrogen pretreatment at 900 ° C. In the case of supported catalysts, the decomposition of the catalyst particles by the growth proceeds distinctly differently from the growth of unsupported catalysts, so that the disclosure there provides no teaching for the further optimization of unsupported catalysts.
• the invention also relates to the co-precipitated catalysts prepared by this process comprising a reduction step, and to a process for producing carbon nanotubes in which the catalysts according to the invention are used, and the carbon nanotubes with low bulk densities and high yields produced by this CNT production process in high yields Purity.
• even CNTs can be prepared in a ratio Q> 8, 9, 10, 11 or 12 g * L 2 / g 3 .
• the precipitation can be carried out batchwise or continuously.
• metal salt solution and, if appropriate, the precipitation reagent and further components are mixed by means of conveying apparatuses in a mixer having a high mixing intensity.
• Preference is given to using static mixers, Y mixers, multilamination mixers, valve mixers, micromixers, (two-component jet mixers and other similar mixers known to the person skilled in the art.
• a preferred transition metal combination is based on the components manganese and cobalt, optionally with the addition of molybdenum.
• the addition made of one or more metal components are all transition metals, preferably on the elements Fe, Ni, Cu, W, V, Cr, Sn based metal components.
• Another preferred embodiment of the catalyst preferably contains 2-98 mol% Fe and 2-98 mol% Mo based on the content of active components in metallic form. Particularly preferred is a content of 5-90 mol%> Fe and 2-90 mol%> Mo, more preferably a content of 7-80 mol%> Fe and 2-75 mol%> Mo. The sum the proportions of Fe and Mo do not necessarily result in 100 mol%, inasmuch as further elements are added as mentioned above. An addition of 0.2-50 mol% of one or more further metal components is preferred.
• the mixed catalysts produced by co-precipitation are reduced according to the invention (reduction step, reductive calcination).
• the reduction can be carried out at pressures of from 20 mbar to 40 bar, preferably from 1 to 20 bar, more preferably from 1 to 4 bar. Also preferred is a range of 100 mbar to normal pressure (about 1 atm or 1013 mbar).
• a Combination of oxidative, inert and reductive calcination performed to reduce the sintering of cobalt and adjust the phase at higher temperatures.
• the conditions mentioned above for the individual steps can be set.
• the catalyst after the reduction step is again mixed with a thin oxide layer, e.g. passivated with oxygen gas or an oxygen-containing gas or gas mixture.
• a thin oxide layer e.g. passivated with oxygen gas or an oxygen-containing gas or gas mixture.
• This passivation is preferably carried out by passing over up to 5% by volume of oxygen, preferably 0.001-5,000% by volume, of oxygen-containing gas or gas mixture at room temperature for at least 10 minutes, for example about or at least 15 minutes. and then gradually increasing the oxygen content in the gas mixture to 20 vol .-% oxygen.
• the time to increase the oxygen content to 20% by volume can also be chosen longer, without damaging the catalyst.
• the production of carbon nanotubes can be carried out in different reactor types. Examples include solid-bed reactors, tubular reactors, rotary tubular reactors, moving bed reactors, reactors with a bubbling, turbulent or irradiated fluidized bed, called internally or externally circulating fluidized beds. It is also possible to place the catalyst in a particle-filled reactor falling, for example, under the above classes. These particles may be inert particles and / or consist entirely or partially of a further catalytically active material. These particles can also be agglomerates of carbon nanotubes.
• the process can be carried out, for example, continuously or batchwise, with continuous or discontinuous reference to both the supply of the catalyst and the removal of the carbon nanotubes formed with the spent catalyst.
• the reduction step further succeeds in reactivating catalysts which have been calcined and inactivated by high temperatures in an oxidative atmosphere, i. With the reduction can be activated "dead glow" catalyst again.
• the percolation curve corresponds to the curve that results from the application of specific resistance of a composite as a function of the degree of filling of the matrix (for example, a polymer) with CNT.
• the resistance is usually very high for non-conductive Matrice initially. As the degree of filling increases, guide paths of CNT in the composite increasingly form.
• a CNT bed template of about 30 cm unexpanded height was first introduced to ensure good mixing.
• the reactor was then made inert with nitrogen and heated to a temperature of 650 ° C.
• An amount of 24 g of catalyst 1 according to Example 1 was then metered in.
• the uncalcined, dried catalyst of Example 3 was subjected to the following calcining series in a tube furnace: i) reductive calcination in H 2 at 700 ° C for 1 h, ii) inert calcination in N 2 at 850 ° C for 2 h and after cooling to Room temperature used directly in the CNT synthesis.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Nanotechnology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Composite Materials (AREA)
• Catalysts (AREA)
• Carbon And Carbon Compounds (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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Publications (2)

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Citations (12)

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• 2010
  • 2010-02-16 DE DE102010008173A patent/DE102010008173A1/de not_active Withdrawn
• 2011
  • 2011-02-14 WO PCT/EP2011/052086 patent/WO2011101300A2/de not_active Ceased
  • 2011-02-14 JP JP2012553273A patent/JP2013519515A/ja not_active Withdrawn
  • 2011-02-14 CN CN2011800097730A patent/CN102770206A/zh active Pending
  • 2011-02-14 US US13/579,007 patent/US20130039839A1/en not_active Abandoned
  • 2011-02-14 EP EP11704211A patent/EP2536502A2/de not_active Withdrawn
  • 2011-02-14 KR KR1020127021267A patent/KR20130026419A/ko not_active Withdrawn

Patent Citations (13)

Non-Patent Citations (5)

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