Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
  • C10G1/10—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal from rubber or rubber waste
• • 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
  • C01B32/158—Carbon nanotubes
  • C01B32/16—Preparation
  • C01B32/162—Preparation characterised by catalysts
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/12—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by dry-heat treatment only
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
  • C10G1/002—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal in combination with oil conversion- or refining processes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L8/00—Fuels not provided for in other groups of this subclass
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• This invention relates to a process for disposing of and recycling organic waste materials, particularly waste plastics materials which is suitable for the conversion of such materials into reusable materials of high added value; in particular the invention relates to a process which uses waste plastics materials and converts them into carbon nanotubes.
• EP-A-I 522 355 describes a process for obtaining carbon-containing material, essentially carbon black, from the pyrolysis of wastes.
• the carbon black so obtained can be converted into activated carbon and carbon nanotubes by conventionally known methods, such as electric arc and laser ablation.
• US 6 444 864 describes a process for the recycling of polymer waste materials with the production of nanotubes through the Plasma Enhanced Chemical Vapour Deposition (PECVD) technique.
• PECVD Plasma Enhanced Chemical Vapour Deposition
• use is made of the plasma effect produced between two electrodes by means of radio frequencies or microwaves to bring about decomposition of the carbon-containing precursors and as a consequence, under suitable conditions, the formation of nanotubes.
• the process described there makes it necessary to reduce the polymer waste to a powder, and this is delivered in the powdered state to the electric arc where pyrolysis and nanotube formation take place simultaneously.
• One disadvantage of this procedure lies in the fact that the polymer, as often happens, contains fillers, and these remain mixed with the nanotubes, making it necessary to use particularly expensive and complex procedures to recover the nanotubes.
• the PECVD process has disadvantages such as the inability to operate on a large scale, the need to operate with quite stringent process parameters which do not allow any flexibility in production/conversion, and also a reagent conversion yield and a rate of deposition which are unsatisfactory.
• US 2006/062 714 describes a process in which the carbon nanotubes are produced by burning an organically-modified montmorillonite (organoclay) composite in air in the presence of a mesoporous nickel-based catalyst, that is a supported catalyst.
• organically-modified montmorillonite (organoclay) composite in air in the presence of a mesoporous nickel-based catalyst, that is a supported catalyst.
• supported catalysts nevertheless has many disadvantages such as low contact surface area, high sensitivity to poisoning reagents and also, because these catalysts become inactive in a short time, only a low efficiency and low flexibility batch process can be developed.
• the abovementioned process also requires the polymer to be premixed with organoclay and catalyst, which cannot be applied to thermosetting plastics materials (such as epoxy resins, polyurethanes, etc.), that is to those materials which are most advantageous for pyrolytic recycling. Premixing with extruders constitutes an additional cost.
• large quantities of hydrofluoric acid, which is highly toxic, and sulphuric acid need to be used in order to recover the carbon nanotubes, making the method potentially highly polluting.
• WO2006/033457 describes a process for the production of nanotubes which uses a vegetable oil as a source of carbon, in which the oil is sprayed onto a metal catalyst supported on a silica gel, aluminium, magnesia, silica-alumina and zeolite support.
• One object of the invention is to provide a technically and economically advantageous process for converting waste plastics materials into carbon nanotubes.
• Another object of the invention is that of providing a process which can be used in the context of conventional processes for the heat treatment of plastics and organic wastes which makes it possible to use advantageously products resulting from the aforesaid heat treatment, with the production of a material such as carbon nanotubes having a high added value.
• Another object of the invention is to provide a process which can be operated continuously, in a controllable and flexible way, and with a high efficiency of conversion of the reagents into carbon nanotubes.
• the object of the invention is a process for recycling waste plastics materials comprising a stage of pyrolysing the said plastics materials and a stage of converting the gaseous pyrolysis products into carbon nanotubes, characterised in that the stage of converting the gaseous products is carried out through vapour phase chemical deposition in inert gas with the help of unsupported organometallic catalyst.
• the pyrolysis stage may be carried out using conventional techniques for the treatment of wastes, using temperatures between 300°C and 800°C, to convert the material from the solid state into gaseous substances comprising aromatic and aliphatic compounds, and liquid products (pyrolysis oil), with the formation of a waste which depending upon the nature of the plastics materials used essentially comprises carbon black, inorganic fillers (calcium carbonate, talc, etc.) and metals.
• the pyrolysis is preferably performed in a nitrogen atmosphere, and the temperature conditions are determined according to the nature of the waste plastics materials used with a view to maximising the generation of gaseous compounds of an aromatic nature.
• the pyrolysis conditions may be selected to maximise the production of aromatic polycyclic hydrocarbons which in conventional processes for the pyrolysis of organic wastes constitute an undesired component, in that they are of a toxic nature, while their presence in the process according to the invention is instead advantageous in that it is useful for improving the yield of carbon nanotubes.
• the process according to the invention has the considerable advantage that it uses such hydrocarbons as a useful and advantageous raw material for the production of nanotubes.
• the pyrolysis temperature lies between 300°C and 800°C.
• temperatures between 350°C and 45O 0 C are preferable for polymer wastes in which epoxy resins constitute the fraction of greatest relative weight.
• gaseous hydrocarbon flow obtained from pyrolysis may be subjected to a stage of catalytic reforming before being delivered to the stage of conversion into nanotubes, in order to increase the aromatic component.
• the stage of vapour phase chemical deposition for producing nanotubes can be carried out continuously, feeding the carbon-containing gases obtained into an environment maintained at the pyrolysis temperature for such carbon-containing gases, preferably through a carrier flow of inert gas.
• organometallic catalyst is injected into the flow of carbon-containing gas or directly into the environment in which these gases are converted into nanotubes.
• the organometallic catalyst used is typically ferrocene in the liquid state, or may be ferrocene in a liquid organic solvent.
• the conversion reactor may be a continuous reactor, for example a tubular reactor (of the horizontal flow type, for example), in which the nanotubes produced are deposited on a solid substrate, for example a substrate of silica (SiO 2 ) or silicon (Si).
• the conversion temperature is generally between 650°C and 900°C.
• the rate of deposition is relatively low (for example 100 nm/s at 700 0 C), while the conversion yield is low (30% by weight), but the intrinsic quality of the nanotubes is better, as confirmed by HR-TEM, SEM and RAMAN analyses.
• the rate of deposition is higher (500 nm/s at 900 0 C), the conversion yield is high (50% by weight), but the intrinsic quality of the nanotubes is poorer, as confirmed by the analyses indicated above.
• Unconverted gases mainly consisting of aliphatic hydrocarbons, are removed from the conversion reactor. These gases can be used as a fuel in a heat generator, where the heat produced may be used to heat the conversion reactor and/or the pyrolysis reactor.
• the process according to the invention makes it possible to convert organic wastes into nanotubes, particularly: a) wastes of polymeric materials of a thermoplastic nature, also including mixtures thereof b) wastes of polymeric materials of a thermosetting nature, elastomers included, also including mixtures thereof c) materials of a wood-cellulose nature, deriving from wastes from the processes for upgrading biomasses
• thermosetting fraction Predominates
• the polymer wastes may comprise: a) polymer wastes deriving from electronic wastes, having for example the following formulation as a percentage by weight:
• inorganic fillers mainly silica c
• silica c polymer wastes deriving from urban solid wastes, having for example the following percentage formulation by weight:
• Pyrolysis zone The reagents come from a pyrolysis chamber where a sample obtained by shredding printed circuits has been heated to 600°C in a flow of nitrogen (100 ml/min).
• the nanotubes are collected through filtering or a separating cyclone.

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Cited By (5)

Citations (3)

• 2007
  • 2007-12-20 IT ITTO20070923 patent/ITTO20070923A1/it unknown
• 2008
  • 2008-12-19 WO PCT/IB2008/055447 patent/WO2009081362A1/en active Application Filing

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