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Novel carbonization process of PAN-nanofiber mats with enhanced surface area and porosity


Kurzfassung

This innovative carbonization process of carbon precursor fibers creates in a fast and energy saving manner carbon fibers (CF) which are highly porous (small pore diameters from 0.1 to 10 nm) and have a high surface area (100 to 2500 m2/g). The pyrolysis step needs only minutes or even seconds.

No additional additives like pore-providing templates, catalytic compounds or corrosive liquids are required. However, filler materials like pigments, dyes, graphene nanoplatelets or metal- and semiconductor nanoparticles can be admixed to vary the performance of the produced carbon fibers, e.g. to increase electrical conductivity. Overall, this technology combines conventional carbonization and activation treatments into one process and is more economical by saving time, costs and resources compared to already known thermal carbonization methods.

Applications of carbon fibers are known in the art. Electric applications like super caps and electrodes or filtration and adsorption for gas, water and solvent purification might be preferable.


Hintergrund

This innovative carbonization process of carbon precursor fibers creates in a fast and energy saving manner carbon fibers (CF) which are highly porous (small pore diameters) and have a high surface area. 

Filler materials like pigments, dyes, graphene nano-platelets or metal- and semiconductor nanoparticles can be admixed to vary the performance of the produced carbon fibers, e.g. to increase electrical conductivity. Applications of carbon fibers are known in the art. However, electric applications like super caps and electrodes or filtration and adsorption for gas, water and solvent purification will be preferable.


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Problemstellung

In general, the process to manufacture carbon fibers uses two steps. First, the stabilization step, which converts the precursor polymer into an infusible structure in an oxidizing atmosphere and second, the pyrolysis step (i.e. graphitization). The pyrolysis usually requires temperatures between 700 °C and 4000 °C to gain the desired graphitic structures. Although varying alternative procedures exist, all known thermal carbonization steps are time-consuming and use energy consuming large ovens.  Therein the fibers are subject to thermal gradients, resulting in slow release of the gaseous carbonization byproducts, generating undesired and smooth carbon fiber surfaces. Furthermore, additional chemical activation steps to improve the surface area require large amounts of corrosive liquids. 

In summary, the known manufacturing processes for carbon fibers of today suffer from inhomogeneous pyrolysis and require additional treatment steps or additional compounds/catalysts.


Lösung

Inventors at DWI, Aachen have developed a novel technology to manufacture carbon fibers of increased purity, which have in addition a high surface area and wherein a high porosity of the carbon fibers is already induced during carbonization and pyrolysis (i.e. graphitization). At the same time, neither an additional activation step nor additional compounds are needed. 

The innovative process uses IR lasers (alternatively microwave or assisted plasma heating can be used) allowing for precise, homogenous transfer of energy into the fleece and causing very fast blowout of the gaseous carbonization byproducts. By using IR lasers, ovens become obsolete.

Overall, this technology combines conventional carbonization and activation treatments into one process and is more economical by saving time, costs and resources compared to already known thermal carbonization methods.


Vorteile

  • Fast pyrolysis step within minutes or even seconds
  • Energy saving
  • Nanometer sized pore diameters  from  0.1 to 10 nm
  • High surface area from 100 to 2500 m2/g
  • Increased purity, i.e. carbon content
  • No additional additives like pore-providing templates, catalytic compounds or corrosive liquids needed
  • Filler materials like metal- and semiconductor nanoparticles or graphene nanoplatelets can be mixed in to vary the performance of the carbon fibers 
  • Process uses  PAN, pitch, cellulose or lignin derived precursor material

Anwendungsbereiche

Efficient production of carbon fibers

  • highly porous
  • high surface area

Service

Technologie-Lizenz-Büro GmbH is responsible for the commercialization of this technology and assists companies in obtaining licenses.


Technologie-Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

Dr. Frank Schlotter
+ 49 721 790 040
fschlotter@tlb.de
www.tlb.de
Adresse
Ettlinger Straße 25
76137 Karlsruhe



Entwicklungsstand

Funktionsnachweis


Patentsituation

  • EP anhängig

Stichworte

carbon fiber, carbonization process, high purity, high surface area, pyrolysis, PAN, pitch

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