EA042394B1 - OBTAINING A NETWORK FROM CRYSTALLINE CARBON STRUCTURES - Google Patents

Description

The present invention relates to the field of obtaining grids from crystalline carbon structures with improved properties and is directed to new methods for obtaining such grids from structures. The present invention relates in particular to the field of carbon black production.

State of the art

The carbon black industry is focused on the production of allotropic forms of carbon, mainly differing from graphite and amorphous carbon in its physical arrangement, for use in the production of rubber products such as tires and the like, in printing, electronics and cable coatings, in the production of varnishes and paints, including applications for use in which the reinforcing and/or pigmentary properties of carbon black are desired.

In the field of obtaining carbon black, various methods or technologies are known. Carbon black is mainly produced by partial combustion processes, starting with a carbonaceous gas such as methane or acetylene. Such a process is sometimes referred to as a carbon black furnace process and uses a furnace containing a burner or combustion chamber followed by a reactor. The kiln process is typically characterized by low oxygen levels, low densities, short residence times and high temperatures. As a first step in the carbon black furnace process, the hydrocarbons are atomized at typical temperatures of 1200 to 1900° C., as described in Ullmanns Encyklopadie der technischen Chemie, Volume 14, page 637-640 (1977). For this, a zone having a high energy density is created by burning fuel gas or liquid fuel with oxygen or air, and carbon black raw materials are introduced into it. Carbon black feedstocks are atomized under these hot combustion conditions; oxygen levels are generally supplied at a ratio of two volumes of carbon black feedstock to about one volume of oxygen, to achieve full oxygen consumption in the combustion process. The structure and/or porosity of the final carbon black product can be affected by the presence of alkali metal or alkaline earth metal ions during carbon black formation, and for this reason, such additives are often added in the form of aqueous solutions that are sprayed over agglomerates of carbon black starting materials. The reaction is only completed by injecting water (quenching) and the carbon black is collected at a temperature of about 200-250°C and separated from the exhaust gases by conventional separators or filters. Due to the low bulk density, the resulting carbon black is then granulated, for example transferred to a pelletizer with the addition of water, to which small amounts of pelletizing aids may be added. In chronological order, and by no means limiting the scope of carbon black furnace technology, US 2,672,402, US 4,292,291, US 4,636,375, WO 2000/032701 and US 2004/0248731 describe conventional or conventional carbon black production. Their contents are hereby incorporated by reference herein. It should be noted that there are also alternative methods such as the lamp black method, the thermal black method, the acetylene black method and channel black, all of which are variants of the method described above, with some type of carbon black being produced at the end. The most innovative is the plasma method for producing carbon black, with the advantages of eliminating direct carbon dioxide emissions and reducing fossil fuel consumption. In general, these methods for producing carbon black under oxygen deficiency are very similar except for finding different ways to obtain pyrolysis temperature conditions. To date, however, the industry is still struggling to produce carbon black using oxygen-deficient reduction methods with parameters comparable to carbon black produced by conventional partial combustion.

GB 1514130 (1976) also describes a process for producing carbon black from liquid hydrocarbons by partial combustion and cracking of hydrocarbons in a furnace plant. An emulsion of water and liquid hydrocarbons is introduced into the combustion zone of the furnace, with the intended use of water to optimize the atomization of hydrocarbons. The method of thermal atomization of liquid hydrocarbons, which themselves can only partially evaporate, is associated with the explosive evaporation of water at the moment when the emulsion passes through the hot combustion zone. The process results in a higher yield of carbon black and shorter reaction times. The type of emulsion that could be used is not described. The various structures are not reported.

US 3494740 (1970) also describes the production of carbon black by introducing into the reaction zone of a carbon black furnace an additive containing a metal selected from the group consisting of nickel, vanadium, iron, cobalt and mixtures thereof, in an amount ranging from 1 to 80 parts by weight per million parts by weight of the hydrocarbon feedstock into said furnace. The metal may be introduced in water, in oil, or in emulsion to realize uniform dispersion in the hydrocarbon feedstock. The properties of carbon black are discussed in Table. 1. The type of emulsion that could be used is not described. The various structures are not reported.

US 2015/064099 relates to processes for producing carbon black using preheated soot control feedstocks. Water is used for quenching.

- 1 042394

The essence of the invention

The authors have found that well-established reductive (pyrolysis) or oxidative (combustion) processes for producing carbon black can be used to produce networks of crystalline carbon structures having all kinds of advantageously improved electrical, mechanical, and thermal properties by introducing the concept of single-phase emulsification using thermodynamically stable microemulsions. water/oil type or bi-continuous type, with nanoparticles of metal catalyst, for conventional (furnace) production of carbon black. Thus, the present invention relates to a method for producing networks of crystalline carbon structures by providing a thermodynamically stable single phase emulsion containing an oil, preferably C14 or higher, more preferably a carbon black starting material oil, water, and at least one surfactant. substance as well as metal catalyst nanoparticles, and exposing the emulsion, preferably emulsified carbon black raw materials, carbon black production process, carbonizing said carbon black raw materials at elevated temperatures above 600° C., preferably above 700° C., more than preferably above 900°C, even more preferably above 1000°C, most preferably above 1100°C, preferably up to 3000°C, more preferably up to 2500°C, in particular up to 2000°C.

In the text and claims, a single-phase emulsion is a water-in-oil (water/oil) microemulsion or a bicontinuous microemulsion containing metal catalyst nanoparticles.

In an aspect, the present invention relates to the use of such a single-phase emulsion, preferably emulsified carbon black raw materials (i.e., a single-phase emulsion containing carbon black raw materials) to carbonize the emulsion in a carbon black manufacturing process, preferably in a carbon black furnace manufacturing process, thus obtaining networks of crystalline carbon structures. The emulsion is preferably pulverized and atomized in a reactor at the above elevated temperatures. Again, it has been found that the single phase emulsion should be a water/oil microemulsion or a bicontinuous microemulsion containing metal catalyst nanoparticles.

As viewed through the eyes of one skilled in the art, the use of water should be at least minimized, and preferably eliminated, in the reaction sector in the conventional carbon black process to obtain adequate yield and preferred carbon black spherical structures where water is further used only to complete the carbon black reaction in the reactor. At best, water is sometimes used as a carrier in the spraying of alkali metal and alkaline earth metal ions over the carbon black material, where the porosity of the carbon black product can be fine-tuned to suit market needs in the final stages of the sintering process. Depending on the source, the carbon black feedstock may actually even be dehydrated before entering the process to increase fuel density and optimize atomization. With such widespread reluctance to use water, let alone more, in conventional carbon black production, except for the purpose of quenching in the final stages, the idea of emulsifying carbon black feedstocks prior to atomization is beyond the imagination of those skilled in the art. However, the authors found that replacing the conventional production of carbon black by atomization with a stable single-phase emulsion containing oil of carbon black starting materials in the reactor has a significant impact, in which a new crystalline carbon material is obtained, consisting of a network of structures, usually nanofibers, instead of the usual amorphous carbon black based on aggregates of spherical particles. The crystalline carbon structures of the networks are so different in morphology that they have properties that are different from and even superior to carbon black aggregates, some of which are further discussed below.

Without wishing to be bound by any theory, the authors believe that the orientation and structuring of the surfactant, oil phase and aqueous phase molecules together with the metal catalyst nanoparticles induce a network formation process that is unique to this new material and method. Metal catalyst nanoparticles have been found to be the most important. The micro and macro structures of emulsions (either water in oil or bicontinuous) are thought to act as a precursor/sketch for the final network of carbon structures from which the carbon containing fractions (oil phase and surfactant) will form fibers and compounds, while the water fraction assists in oil/surfactant phase orientation and network porosity. The presence of a metal catalyst facilitates the carbonization of the carbon components in a fiber structure instead of the spherical orientation usually obtained. A mixture of immiscible oil and water phases will not produce these structures, ie without the presence of a metal catalyst in a thermodynamically stable matrix. After the atomization of the emulsion at high temperatures, the carbonization process instantly freezes the carbon fractions in their emulsion structure in the presence of

- 2 042394 metal catalyst, while the water evaporates, leaving a grid of (nano)fibers. In this process, the inventors have found the key to obtaining carbon starting materials, ie oil, such as carbon black starting materials, in the form of a single-phase emulsion, as described above, for the atomization process. The authors have also found that mixtures of water and starting materials or otherwise thermodynamically unstable emulsions alone are detrimental to the process and will not produce networks of crystalline carbon structures. Additional evidence is provided below.

The authors also found that single-phase emulsions subjected to atomization and subsequent carbonization should contain metal nanoparticles that act as catalysts in the formation of these crystal networks. An increased concentration of metal catalyst nanoparticles further increases the yield. The most important is the use of bicontinuous microemulsions or water in oil (water/oil) microemulsions, where the emulsions contain metal catalyst nanoparticles, these emulsions contain an oil/surfactant continuous phase, thus already forming a network structure. Bicontinuous microemulsions are most preferred.

Brief description of the drawings

Fig. 1A is a diagram of a continuous furnace method for producing carbon black of the present invention, which includes, along the axis of the reactor 3, a combustion zone 3a, a reaction zone 3b and a completion zone 3c, by generating a hot exhaust gas stream a1 in the combustion zone by burning fuel a in an oxygen-containing gas b and passing the exhaust gases a1 from the combustion zone 3a to the reaction zone 3b, spraying (atomizing) a single-phase emulsion c in the reaction zone 3b containing hot exhaust gases, carbonizing said emulsion at an elevated temperature, and quenching or stopping the reaction in the zone 3c by completing injection of water d to obtain grids e of crystalline carbon structures according to the present invention.

Fig. 1B is a diagram of a semi-continuous process for producing carbon black, where a single phase emulsion c is atomized with a nozzle 4 at the top of the reactor 3 in a reactor zone 3b at elevated temperatures, said emulsion is carbonized at an elevated temperature in a reactor zone 3b, and a network of crystalline carbon structures e collected at the bottom of the reactor. In addition, there are two gas inlets that enter the reactor from above for adding an inert gas f, preferably nitrogen, to control and/or reduce oxygen levels, and for introducing a carbonaceous gas g, preferably acetylene or ethylene, into the reactor.

Fig. 2A and 2B are SEM (scanning electron microscope) images of carbon black and grids of carbon structures, respectively.

Fig. 3 shows an SEM image of networks of crystalline carbon structures obtained in a bicontinuous microemulsion with 100 mM FeCl ₃ metal catalyst.

Fig. 4 shows the modulus of elasticity according to ISO 527 for carbon meshes (squares) and for glass fibers (circles), it shows the mechanical strength of the crystal meshes, which is comparable to the parameters of the fibers. Carbon black has not been found to impart any reinforcing properties to the composite.

Fig. 5 shows the volume resistance of various compounds (polyamide PA6: squares; PET: circles) obtained under various loads of nets of crystalline carbon structures prepared using the recipe according to example 1.

Embodiments of the invention

1. A method for producing networks of crystalline carbon structures in a reactor 3, which contains a reaction zone 3b and a completion zone 3c, by injecting a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles into the reaction zone 3b, which is at a temperature above 600 °C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably up to 3000°C, more preferably up to 2500°C, most preferably up to 2000°C , to form nets of crystalline carbon structures e, moving these nets e to the completion zone 3c and quenching or stopping the formation of nets of crystalline carbon structures in the completion zone by injecting water d.

2. The method according to Embodiment 1, wherein said reactor is a carbon black furnace reactor 3, which comprises, along the axis of the reactor 3, a combustion zone 3a, a reaction zone 3b and a completion zone 3c, by obtaining a hot exhaust gas stream a1 in the zone combustion by burning fuel in oxygen-containing gas b and passing exhaust gases a1 from combustion zone 3a to reaction zone 3b, spraying water-in-oil microemulsion or bicontinuous microemulsion c containing metal catalyst nanoparticles in reaction zone 3b containing hot exhaust gases, carbonizing said emulsion at temperatures above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably up to 3000°C, more

- 3 042394 preferably up to 2500° C., most preferably up to 2000° C., and quenching or stopping the reaction in the completion zone 3c by injecting water d to obtain networks e of crystalline carbon structures.

3. The method according to any of the previous embodiments, where the oil phase in the emulsion is aromatic and/or aliphatic, preferably it contains at least 50 wt.% compounds C14 or higher, relative to the total weight of the oil phase.

4. The method according to any of the previous embodiments, wherein said emulsion contains at least 1 mM of metal catalyst nanoparticles, preferably having an average particle size between 1 and 100 nm.

5. A network of crystalline carbon structures, which can be obtained using the method according to any of the previous embodiments, where these carbon structures are chemically linked together using a variety of compounds, including Y- and H-connections.

6. The mesh according to embodiment 5 having at least one, preferably at least two, more preferably at least three, most preferably all of the following properties:

(i) an iodine number (IAN) of at least 250 mg/g according to ASTM D1510;

(ii) a nitrogen adsorption surface area (N2SA) of at least 250 m ² /g according to ASTM D6556;

(iii) a statistical surface area (STSA) of at least 120 m ² /g according to ASTM D6556;

(iv) an oil absorption number (OAN) of at least 150 ^cc /100 g according to ASTM D2414.

7. Mesh according to embodiment 5 or 6, wherein said structures have an average thickness of 1-400 nm, preferably between 5 and 350 nm, more preferably up to 100 nm, in one embodiment, between 50 and 100 nm, and/or an average length in the range of 10,010,000 nm, preferably 200-5000 nm, more preferably 500-5000 nm; and/or where the structures have an average aspect ratio of length to thickness of at least 2.

8. Composite containing networks of carbon structures according to any one of embodiments 5-7, further containing one or more polymers, for example, to impart mechanical strength, electrical conductivity or thermal conductivity of the specified polymer-based composite, and where these networks are in any amount within the range 1-70 wt.%, preferably 10-50 wt.%, more preferably between 20 and 40 wt.% in relation to the total weight of the polymer in the composite.

9. The composite of Embodiment 8 having an E modulus increasing with mesh concentration as measured according to ISO 527.

10. The use of emulsified carbon black raw materials in a carbon black manufacturing process, preferably a carbon black furnace manufacturing process, to produce networks of crystalline carbon structures.

11. A process for the semi-continuous production of networks of crystalline carbon structures in a reactor 3, wherein a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles is injected from the top of the reactor 3, preferably by atomization using an aerosol inlet 4, to produce an aerosol, and where said gauzes e are formed at an elevated temperature of at least 600°C, preferably 700-1200°C and deposited at the bottom of the reactor, and where the elevated temperature is obtained using pyrolysis (e.g. a heat source outside the reactor, using N2 depleted in oxygen) or by combustion (a heat source inside the reactor using air or oxygen).

12. A process for the continuous production of networks of crystalline carbon structures in a reactor 3, wherein a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles is injected from the top of the reactor 3, said reactor being preferably a thermal carbon black reactor, preferably by means of spraying using an aerosol inlet 4 to produce an aerosol, and where said networks e are formed at an elevated temperature of at least 600°C, preferably 700-1200°C, and deposited at the bottom of the reactor, and where the elevated temperature is obtained using combustion (heat source inside the reactor, using air or oxygen), but where the emulsion is injected only under pyrolysis conditions.

Detailed description

The present invention can best be described as a modified method for producing carbon black, where modified is understood to mean that an appropriate oil, preferably an oil containing at least 14 C atoms (>C14), such as a carbon black feedstock oil (CBFS), is fed into the reaction zone of the carbon black reactor as part of a single-phase emulsion, which is a thermodynamically stable microemulsion containing metal catalyst nanoparticles. The emulsion is preferably fed into the reaction zone by spraying, thus atomizing the emulsion to droplets. Although the process can be carried out in batch or semi-continuous mode, the modified method

- 4 042394 way to obtain carbon black is preferably carried out as a continuous process. A single-phase emulsion is a microemulsion containing metal catalyst nanoparticles. A preferred single phase emulsion contains CBFS oil, and may be referred to as emulsified CBFS in the context of the present invention.

In one embodiment, the present invention relates to a method for producing networks of crystalline carbon structures according to the present invention in a reactor 3, which contains a reaction zone 3b and a completion zone 3c, by injecting a single-phase emulsion c, which is a microemulsion containing nanoparticles of a metal catalyst, preferably , an emulsion containing CBFS according to the present invention, into the reaction zone 3b, which is at a temperature above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100° C, preferably up to 3000° C., more preferably up to 2500° C., most preferably up to 2000° C., producing networks e of crystalline carbon structures, transferring these networks e to the completion zone 3c and quenching or stopping the formation of networks of crystalline carbon structures in the completion zone by water injection d. The single phase emulsion is preferably sprayed into the reaction zone. Referring to Fig. 1A.

In a preferred embodiment, the present invention relates to a process for producing networks of crystalline carbon structures of the present invention in a carbon black furnace reactor 3, which comprises, along the axis of the reactor 3, a combustion zone 3a, a reaction zone 3b and a completion zone 3c, by providing flow of hot exhaust gases a1 in the combustion zone by burning the fuel a in an oxygen-containing gas b and passing the exhaust gases a1 from the combustion zone 3a to the reaction zone 3b, spraying (atomizing) a single-phase emulsion c according to the present invention, preferably a microemulsion containing nanoparticles of a metal catalyst, preferably, an emulsion containing CBFS in the reaction zone 3b containing hot exhaust gases, carbonizing said emulsion at elevated temperatures (above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000° C, more preferably above 1100°C, preferably up to 3000°C, more preferably up to 2500°C, most preferably up to 2000°C), and abrupt cooling or suspension of the reaction (i.e. the formation of networks of crystalline carbon structures e) in zone 3c completion by water injection d. The reaction zone 3b contains at least one inlet (preferably a nozzle) for introducing the emulsion, preferably by means of atomization. Referring to Fig. 1A.

The residence times of the emulsion in the reaction zone of the carbon black furnace reactor can be relatively short, preferably in the range of 1-1000 ms, more preferably 10-100 ms.

In accordance with conventional methods for producing carbon black, the oil phase may be aromatic and/or aliphatic, preferably containing at least 50 wt.% compounds C14 or higher, more preferably at least 70 wt.% compounds C14 or higher (in relation to the total mass of oil). A list of typical oils that can be used to make stable emulsions, but are not limited to, include carbon black feedstock (CBFS) oils, phenolic oils, anthracene oils, fatty acids (short-medium-long chain), fatty acid esters. acids and paraffins. The oil is preferably a C14 compound or higher. In one embodiment, the oil preferably has high aromaticity. In the art, aromaticity is preferably characterized in terms of the Bureau of Mines Correlation Index (BMCI). The oil preferably has a BMCI >50. In one embodiment, the oil has low aromaticity, preferably it has a BMCI <15.

CBFS is an economically attractive source of oil in the context of the present invention, and is preferably a mixture of heavy hydrocarbons containing predominantly C14-C50 compounds, the sum of C14-C50 compounds is preferably at least 50 wt.%, more preferably at least , 70 wt.% of the starting materials. Some of the most important feedstocks used to produce carbon black include clarified slurry in oil (CSO) from liquid catalytic cracking of gas oils, ethylene cracker residue from steam cracking of naphtha and coal oils. The presence of paraffins (<C15) severely limits their usefulness and higher aromaticity is preferred. The concentration of aromatic compounds determines the rate at which carbon nuclei form. Carbon black feedstocks preferably have high BMCIs so that they can produce high yields with minimal heat input, thereby reducing production costs. In the preferred embodiment, and in accordance with current CBFS specifications, oils, including blends of oils, have a BMCI value greater than 120. While one of skill in the art will have no problem understanding what a suitable CBFS is, purely as a guide, note that in terms of The BMCI value for CBFS is preferably greater than 120, even more preferably greater than 132. The amount of asphaltene in the oil is preferably less than 10% by weight, preferably less than 5.0% by weight of the CBFS. CBFS

- 5 042394 preferably has a low sulfur content, since sulfur adversely affects the quality of the product, leads to a decrease in yield and causes corrosion of equipment.

Preferably, the sulfur content in the oil according to ASTM D1619 is less than 8.0 wt.%, preferably less than 4.0 wt.%, more preferably less than 2.0 wt.%.

The emulsion, preferably the CBFS-containing emulsion, is a single phase emulsion, which is understood to mean that the oil phase and the water phase optically appear as one miscible mixture without visually showing physical separation of oil, water or surfactant. The single phase emulsion may be a macroemulsion or a microemulsion and may be either kinetically or thermodynamically stable. The process by which the emulsion is completely broken down (coalescence), i.e. the system separates into bulk oil and water phases, is generally considered to be controlled by four different droplet loss mechanisms, i.e. Brownian flocculation, stratification, sedimentation flocculation and disproportionation.

A stable single phase emulsion in the context of the present invention is understood to mean that the emulsion does not show physical separation visible to the naked eye, preferably this is reflected in terms of an emulsion showing no change in pH greater than 1.0 pH unit and/or an emulsion showing no change in viscosity greater than 20%, for a period of time that exceeds the time of obtaining a network of carbon structures. The term stable can mean thermodynamically stable or kinetically stable (when energy is added, for example, through agitation). In practice, a single phase emulsion is considered stable if no separation is optically observed, i.e. the single phase is maintained for a period of at least 1 minute after the emulsion has been prepared. Thus, it is preferred that the emulsion maintain its pH within 1.0 pH units and/or its viscosity with a change of less than 20% over a period of time of at least 1 minute, preferably at least 5 minutes after preparation. While long term stability is preferred for handling purposes, note that the preparation process can still benefit from using emulsions that are stable for relatively short periods of time, 1 minute, preferably 5 minutes. By adding energy (agitation), the stability of the emulsion can be extended, and short-term stability can be extended using in-line agitation. Although macroemulsions are not thermodynamically stable and they always revert to their original, immiscible separate oil and water phases, the rate of degradation can be slow enough to make them kinetically stable throughout the production process.

As long as a stable, single-phase emulsion is obtained, the amounts of water and oil are not limited in any way, but it is noted that reducing the amount of water (and increasing the amount of oil) improves the yield. The water content is generally between 5 and 50% by weight of the emulsion, preferably in the range of 10-40% by weight, even more preferably up to 30% by weight, more preferably 10-20% by weight of the emulsion. Although higher amounts of water can be considered, this will come at the expense of output. Without wishing to be bound by any theory, the authors believe that the form and morphology of the networks thus obtained are attributed to the aqueous phase.

The choice of surfactant(s) is not considered to be a limiting factor, provided that the combination of oil, water, and surfactant(s) results in a stable microemulsion as defined above herein. As an additional guide for the person skilled in the art, the surfactant can be selected based on the hydrophobicity or hydrophilicity of the system, ie the hydrophilic-lipophilic balance (HLB). The HLB of a surfactant is a measure of the degree to which it is hydrophilic or lipophilic, determined by calculating values for different regions of the molecule according to the Griffin or Davies method. The appropriate HLB value depends on the type of oil and the amount of oil and water in the emulsion, and can be readily determined by one skilled in the art based on the requirement to maintain a thermodynamically stable, single phase emulsion as defined above. It has been found that an emulsion containing greater than 50 wt% oil, preferably having less than 30 wt% aqueous phase, would be best stabilized with a surfactant having an HLB value greater than 7, preferably greater than 8, more preferably greater than 9, most preferably above 10. On the other hand, an emulsion with at most 50 wt% oil would be best stabilized with a surfactant having an HLB value below 12, preferably below 11, more preferably below 10, most preferably below 9, in particular below 8. The surfactant is preferably chosen to be compatible with the oil phase. In the case where the oil is an emulsion containing CBFS, with that CBFS, a highly aromatic surfactant is preferred, while an oil with a low BMCI, such as one having a BMCI <15, would be best stabilized using aliphatic surfactants. -active substances. The surfactant(s) may be cationic, anionic or non-ionic, or a mixture thereof. One or more non-ionic surfactants are preferred for enhancing

- 6 042394 strokes, since no residual ions will remain in the final product. To obtain a clean tail gas stream, the surfactant structure preferably contains little sulfur and nitrogen, preferably no sulfur and nitrogen. Non-limiting examples of typical non-ionic surfactants that can be used to form stable emulsions are the commercially available Tween, Span, Hypermer, Pluronic, Emulan, Neodol, Triton X, and Tergitol series.

In the context of the present invention, a microemulsion is a dispersion consisting of water, oil (preferably CBFS), and surfactant(s) which is a single optically isotropic and thermodynamically stable liquid with dispersed domain diameters ranging from approximately 1 to 500 nm, preferably 1 to 100 nm, typically 10 to 50 nm. In a microemulsion, the dispersed phase domains are either globular (i.e. droplets) or they are interconnected (to form a bicontinuous microemulsion). In a preferred embodiment, the surfactant tails form a continuous network in the oil phase of a water-in-oil (water/oil) emulsion or in a bicontinuous emulsion. The water domains should contain a metal catalyst, preferably having an average particle size between 1 and 100 nm.

The single phase emulsion, ie a water/oil microemulsion or a bicontinuous microemulsion, preferably a bicontinuous microemulsion, further comprises metal catalyst nanoparticles preferably having an average particle size between 1 and 100 nm. A person skilled in the art will find clear guidance in the field of carbon nanotubes (CNT) regarding the production and use of these types of nanoparticles. These metal nanoparticles have been found to improve networking in terms of both speeds and yields and reproducibility. Methods for preparing the corresponding metal nanoparticles are found in Vinciguerra et al. Growth mechanisms in chemical vapor deposited carbon nanotubes Nanotechnology (2003) 14, 655; Perez Cabero et al. Growing mechanism of CNTs: kinetic approach J. Catal. (2004) 224, 197-205; Gavillet et al. Microscopic mechanisms for catalyst assisted growth of single-wall carbon nanotubes Carbon. (2002) 40, 1649-1663 and Amelinckx et al. A formation mechanism for catalytically grown helix-shaped graphite nanotubes Science (1994) 265, 635-639, their contents regarding the production of metal nanoparticles are incorporated herein by reference.

The metal catalyst nanoparticles are used in a bicontinuous or water/oil microemulsion, preferably in a bicontinuous or water/oil microemulsion containing CBFS. In one embodiment, a bicontinuous microemulsion is most preferred. Preferably, the homogeneity of the metal particles in said (bicontinuous) microemulsion is controlled by mixing a first (bicontinuous) microemulsion in which the aqueous phase contains a metal complex salt that can be reduced to the final metal particles and a second (bicontinuous) microemulsion in which the aqueous phase contains a reducing agent. , which can restore the specified salt of the metal complex; when mixed, the metal complex is reduced, thus forming metal particles. The controlled environment of the (bicontinuous) emulsion stabilizes the particles against sintering or Ostwald ripening. The size, concentration and lifetime of the catalyst particles are easily controlled. Adjusting the average metal particle size in the above range, for example, by changing the molar ratio of metal precursor and reducing agent, is considered a routine procedure. Increasing the relative amount of reducing agent produces finer particles. The metal particles thus obtained are monodispersed, the deviations from the average particle size are preferably within 10%, more preferably within 5%. Also, the present technology does not place restrictions on the real metal precursor, provided that it can be recovered. Non-limiting examples of effective types of catalysts are noble metals (Pt, Pd, Au, Ag), elements of the iron family (Fe, Co and Ni), Ru and Cu. Suitable metal complexes are, but are not limited to, (i) platinum precursors such as H ₂ PtCl ₆ ; H ₂ PtCl ₆ .xH ₂ O; K ₂ PtCl ₄ ; K ₂ PtCl ₄ .xH ₂ O; Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ; Pt(C ₅ H ₇ O ₂ ) ₂ , (ii) ruthenium precursors such as Ru(NO)(NO ₃ ) ₃ ; Ru(dip) ₃ Cl ₂ [dip=4,7-diphenyl-1,10-phenanthroline]; RuCl ₃ or (iii) palladium precursors such as Pd(NO ₃ ) ₂ or (iv) nickel precursors such as NiCl ₂ or NiCl ₂ .xH ₂ O; Ni(NO ₃ ) ₂ ; Ni(NO ₃ ) ₂ .xH ₂ O; Ni(CH ₃ COO) ₂ ; Ni(CH ₃ COO) ₂ .xH ₂ O; Ni(AOT) ₂ [AOT=bis(2-ethylhexyl)sulfosuccinate]. Non-limiting reducing agents that can be used are hydrogen gas, sodium boron hydride, sodium bisulfate, hydrazine or hydrazine hydrate, ethylene glycol, methanol and ethanol. Also suitable for use are citric acid and dodecylamine. The type of metal precursor is not an important part of the present invention. The metal of the particles of the (bicontinuous) microemulsion is preferably selected from the group consisting of Pt, Pd, Au, Ag, Fe, Co, Ni, Ru and Cu, and mixtures thereof, to control the morphology of the networks of carbon structures eventually formed. The metal nanoparticles remain embedded within these structures, where the metal particles are physically attached to the structures. Although not

- 7 042394 there is no minimum concentration of metal particles at which these networks are formed, in fact, networks are formed using a modified method for producing carbon black of the present invention, it was found that the yield increases with the concentration of metal particles. In a preferred embodiment, the active metal concentration is at least 1 mM, preferably at least 5 mM, preferably at least 10 mM, more preferably at least 15 mM, more preferably at least 20 mM, in particular at least least 25 mm, most preferably up to 3500 mm, preferably up to 3000 mm. In one embodiment, the metal nanoparticles are up to 250 mM. These are the catalyst concentrations relative to the amount of the aqueous phase of the (bicontinuous) microemulsion.

The atomization of the single phase emulsion, preferably the emulsion c containing CBFS, is preferably realized by atomization, using a nozzle system 4 which allows the emulsion droplets to come into contact with the hot exhaust gases a1 in the reaction zone 3b, resulting in conventional carbonization, networking and subsequent agglomeration to obtain networks e of the crystalline carbon structures of the present invention. The injection step preferably comprises raising temperatures above 600°C, preferably between 700 and 3000°C, more preferably between 900 and 2500°C, more preferably between 1100 and 2000°C.

In another but related aspect of the present invention, the present invention relates to a process for the semi-continuous production of networks of crystalline carbon structures of the present invention in a reactor 3, where the single phase emulsion c of the present invention is injected from the top of the reactor 3, preferably by spraying using inlet 4 for an aerosol, to obtain an aerosol, and wherein said grids e are formed at a temperature of at least 600°C, preferably 700-1200°C, and are deposited in the lower part of the reactor furnace. Elevated temperature and reaction conditions can be achieved using pyrolysis (eg, a heat source outside the reactor, using oxygen depleted N2) or by combustion (a heat source inside the reactor, using air or oxygen). In another embodiment, for a semi-continuous process, it is convenient to work with gaseous carbonaceous feedstocks above their cracking temperature, for example, methane, ethane, propane, butane, ethylene, acetylene and propylene, carbon monoxide, oxidized hydrocarbons such as methanol; with aromatic hydrocarbons such as toluene, benzene and naphthalene, and with mixtures of the above substances, for example carbon monoxide and methane. Referring to Fig. 1b. Typical residence times are increased over the preferred carbon black furnace process, with emulsion residence times in the reactor typically on the order of 1 hour to 7 days, more preferably 8 hours to 3 days. A single-phase emulsion is, as defined above, a water-in-oil (water/oil) microemulsion or a bi-continuous microemulsion containing metal catalyst nanoparticles.

In this regard, the present invention also relates to a process for the continuous production of nets of crystalline carbon structures in a reactor 3, where the single phase emulsion c of the present invention is injected from the top of the reactor 3, said reactor preferably being a thermal carbon black reactor, preferably by means of spraying using the aerosol inlet 4 to produce an aerosol, wherein said nets e are formed at an elevated temperature of at least 600° C., preferably 700-1200° C., and are deposited at the bottom of the reactor, and the elevated temperature is obtained from using combustion (heat source inside the reactor, using air or oxygen), but the emulsion is injected only under pyrolysis conditions. In another embodiment, a continuous pyrolysis process comprising an initial combustion step conveniently handles gaseous carbonaceous feedstocks above their cracking temperature, such as methane, ethane, propane, butane, ethylene, acetylene and propylene, carbon monoxide, oxygenated hydrocarbons, such as methanol; with aromatic hydrocarbons such as toluene, benzene and naphthalene, and with mixtures of the above substances, for example carbon monoxide and methane. Referring to Fig. 1b. The residence time of the emulsion in the reactor is preferably in the range from 1 to 600 seconds, more preferably from 5 to 60 seconds. A single phase emulsion, as defined above, is a water-in-oil (water/oil) microemulsion or a bicontinuous microemulsion containing metal catalyst nanoparticles.

According to the above-described semi-continuous and continuous processes of the present invention, networks with crystalline carbon structures (i.e., networks of crystalline carbon structures) can be produced. In a related aspect, the present invention thus relates to networks of crystalline carbon structures obtained or obtained using the method of the present invention. The term carbon structures is understood to include sp2-based crystalline allotropic forms of carbon, i.e. substances in which a carbon atom is bonded to adjacent three carbon atoms in a hexagonal structure, including graphene, fullerene, carbon nanofibers, and carbon nanotubes. The method of the present invention makes it possible to grow networks of crystalline carbon structures formed from carbon structures.

- 8 042394 round, which are chemically connected to each other using a variety of compounds, including Y- and H compounds. In the context of the present invention, the mesh is preferably understood to comprise at least 3, preferably at least 5, more preferably at least 10, more preferably at least 100, more preferably at least 500 chemically bonded nodes.

The meshes preferably have at least one, preferably at least two, more preferably at least three, most preferably all of the following properties:

(i) an iodine number (IAN) of at least 250 mg/g, more preferably at least 300 mg/g, preferably 300-1000 mg/g according to ASTM D1510;

(ii) a nitrogen adsorption surface area (N2SA) of at least 250 m ² /g, more preferably at least 300 m ² /g, preferably 300-1000 m ² /g, according to ASTM D6556;

(iii) a statistical surface area (STSA) of at least 120 m ² /g, more preferably at least 150 m ² /g, preferably 150-1000 m ² /g, according to ASTM D6556;

(iv) an oil absorption number (OAN) of at least 150 cc/100 g, preferably 150-500 ^cc /100 g according to ASTM D2414;

Where

IAN = iodine number: the number of grams of iodine adsorbed per kilogram of carbon black under given conditions, as defined in ASTM D1510;

N2SA=nitrogen adsorption surface area: total carbon black surface area which is calculated from nitrogen adsorption data using BET theory, according to ASTM D6556;

STSA=statistical surface area: the outer surface area of carbon black, which is calculated from nitrogen adsorption data using de Boer theory and carbon black model according to ASTM D6556; And

OAN = oil absorption number: the number of cubic centimeters of dibutyl phthalate (DBP) or paraffin oil absorbed by 100 g of carbon black under given conditions.

The OAN value is proportional to the degree of structural level of carbon black, determined according to ASTM D2414.

For each parameter from IAN, N2SA (or NSA), STSA and OAN - all typical characterization parameters for carbon black materials - meshes show superior properties over conventional carbon black. The meshes of the present invention are preferably characterized by at least one parameter, preferably at least two, more preferably all of the parameters (i), (ii) and (iii), as these are typical ways of characterizing the surface area properties of materials. In one embodiment, the meshes exhibit at least one of (i), (ii) and (iii) and furthermore correspond to (iv).

These network-forming structures can be described as nanofibers that are continuous (i.e., non-hollow), preferably having an average diameter or thickness of 1-400 nm, more preferably between 5 and 350 nm, more preferably up to 100 nm, in in one embodiment, 50-100 nm, compared to an average particle size of 8-500 nm for spherical carbon black particles. In one embodiment, the average fiber length (i.e., the average distance between two connections) is preferably in the range of 100-10000 nm, more preferably 200-5000 nm, more preferably 500-5000 nm, as can be determined, for example, with using SEM. Alternatively, the nanofibers or structures may preferably be described in terms of an average fiber length to thickness aspect ratio of at least 2, preferably at least 3, more preferably at least 4, most preferably at least 5; this provides a sharp contrast to the amorphous (physically associated) aggregates formed from spherical particles produced in conventional carbon black production. The grid aggregates of the carbon structures of the present invention typically have dimensions on the order of 0.1-100 µm, preferably 1-50 µm, as observed by laser diffraction and dynamic light scattering analysis.

The present invention also relates to a composite containing networks of carbon structures of the present invention, additionally containing one or more polymers, for example, to impart mechanical strength, electrical conductivity or thermal conductivity of the specified polymer-based composite. Meshes can be added in any amount adapted to the desired characteristics, for example, 1-70 wt.%, more preferably 10-50 wt.%, even more preferably in the range of 20-40 wt.%, relative to the total weight of the polymer in the composite . In one aspect, the composite exhibits a mesh concentration dependent modulus (E-modulus, i.e. increase with mesh concentration), for example, as measured according to ISO 527.

Examples

Example 1A. Obtaining a grid from crystalline carbon structures.

Prepare 100 gallons (38 liters) of starting materials consisting of

a) slurries in carbon black oil (CBO or CBFS oil);

b) an aqueous phase containing 3500 mm metal precursor salt (FeCl ₃ );

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c) an aqueous phase containing a reducing agent (3650 mm citric acid);

d) surfactant (TritonX; HLB 13.4).

The exact composition of the microemulsions (a+b+d) and (a+c+d) is detailed below.

Emulsion NWO Water / Weight1 ₃ Water/SA TritonX a+b+d 70% 10% 0% 20% a+c+d 70% 0% 10% 20%

Both microemulsions (a+b+d), (a+c+d) are added to each other and a single-phase microemulsion is obtained by stirring, and said microemulsion is stable for more than 1 hour, which is longer than the entire duration of the experiment.

Meshes obtained in this way have the following characteristics:

IAN=382.5 mg/g, according to ASTM D1510;

N2SA=350 m ² /g (ASTM D6556);

STSA=160.6 m ² /g (ASTM D6556);

OAN=170 cm ³ /100 g (ASTM D2414).

Example 2 Carbon black versus mesh.

The carbon nets according to example 1 are compared with conventional carbon black obtained using (a). Standard grade carbon black typically has a nitrogen adsorption surface area (NSA or N2SA) varying up to 150 m ² /g (N100 grade rubber carbon black).

The morphology of the carbon networks is assessed using scanning electron microscopy (SEM). It has been found that the constituent elements of the carbon network are chemically covalently bonded continuous carbon (nano) fibers with an average fiber diameter below 100 nm. On the other hand, the constituent elements of carbon black are granules in which graphite layers are organized in a spherical shape (diameter 8-300 nm). SEM images of the carbon black and the constituent elements of the carbon grids are shown in FIG. 2A and 2B, respectively. It has been found that the carbon networks are organized into 1-100 µm aggregates, while the carbon black aggregates generally fall within the 85-500 nm range.

Example 3. Exposure to metal nanoparticles.

The concentration of the metal catalyst affects the final reaction yields: three bicontinuous microemulsions are prepared, 20 g each, from isopropyl palmitate (35 wt.%), butanol (11.25 wt.%), Tween 80 (33.75 wt.%), water (20 wt.%). While the first batch is prepared without any metal nanoparticles, two batches contain 50 and 200 mM metal nanoparticles from FeCl ₃ (relative to citric acid and FeCl ₃ in a ratio of 10:1). Each of the emulsions is stable throughout the duration of the experiments. The experiment without metal nanoparticles is carried out at least 10 times.

In each case, the emulsions are introduced into the middle part of the quartz tube of the thermal horizontal tubular reactor. The reactor is heated to 750° C. (3 K/min) under a nitrogen flow of 130 cc ^/ min (N.O.) and maintained for 90 minutes at the same temperature. After the first 60 minutes, the nitrogen gas flow is reduced to 100 cm ³ /min (N.O.) and the ethylene gas stream is added at 100 cm ³ /min (N.O.). During the last 30 minutes at 750° C., ethylene is removed by purging from nitrogen at 130 cc ^/ min (N.O.) for the last 30 minutes and then the reactor is cooled down.

Grids from carbon structures are obtained only with the help of metal nanoparticles. In none of the ten experiments without metal nanoparticles, networks are found. A study done in the presence of 200 mM FeCl ₃ shows an increase in the yield of nets from carbon structures compared to the results reported for 50 mM FeCl ₃ .

SEM image of networks obtained using a bicontinuous microemulsion based on isopropyl palmitate (35 wt.%), butanol (11.25 wt.%), Tween 80 (33.75 wt.%) and water (20 wt.%), s 100 mM of Fe nanoparticles is shown in Fig. 3.

Example 4. E-module plot in PA6.

Carbon mesh powder, such as prepared according to the recipe of example 1, is compounded at various loads (10, 20, 30, 40 wt.%) in Polyamide 6 (Akulon F223D), by means of a twin screw extruder (L/D=38, D=25 mm ) and compared with glass fiber (Chopvantage 3540) compounded at loads of 10, 20, 30 wt.%, under the same conditions. E modulus is measured according to ISO 527, on specimens dried as molded tensile test bars. The results are shown graphically in FIG. 4 and show the performance of carbon meshes, which is comparable to glass fiber. Carbon black has not been found to provide significant reinforcement for thermoplastics, at any concentration.

Example 5 Conductivity plot of PA6 and PET.

Volume resistance is measured on various compounds prepared with a carbon mesh prepared using the recipe according to example 1, at various loads of Polyamide 6 (Akulon F223D) and PET (Ramapet N1), by means of a twin screw extruder (L/D=38, D=25 mm).

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The results are shown graphically in FIG. 5. The percolation curves show good dosage control in the static dissipative range and that high conductivity characteristics are achieved at high loads. In contrast, the percolation threshold of carbon black for conductive applications is found at lower dosages, i.e., <20 wt.%, and dosage control in the static dissipative range is unsatisfactory. In addition, carbon mesh compounds do not delaminate up to a load of 30% by weight, while carbon black compounds are known to delaminate even at low fill rates.

Example 6. Mechanical strength.

Carbon nanofiber networks (low IAN, high crystallinity) produced by the modified carbon black production process of the present invention have been found to improve the mechanical properties of thermoplastic (and shrink) polymer resins. The addition of 10 wt% carbon nanofiber networks to the polypropylene copolymer results in a 15% increase in tensile strength (at break) and a 16% increase in modulus of elasticity compared to a pure polymer reference. The Brabender©Plasticorder© is used to mix enough carbon nanofiber and polypropylene meshes at 210°C and 80 rpm. Specimens are pressure molded and examined using an Instron 3366 10 kN tensile tester at 23°C, RH (relative humidity) 50%.______________________________________________

10% CarbonX/PP Young's modulus (tensile stress at 0.05% 0.25%) Tensile stress at tensile strength (zero slope) Tensile strain at tensile strength (zero slope) Tensile stress at break (automatic load shedding) Tensile Strain at Break (Automatic Load Relief) (MPa) (MPa) (%) (MPa) (%) Mean Ah 1459.99 20.05 7.68 19.76 9.80 Standard deviation 149.72 1.13 0.20 1.14 0.91 10.3% 5.6% 2.6% 5.8% 9.3% RR standard Young's modulus (tensile stress at 0.05% 0.25%) (MPa) Tensile stress at ultimate strength (zero slope) (MPa) Tensile strain at tensile strength (zero slope) (%) Tensile stress at break (automatic load shedding) (MPa) Tensile Strain at Break (Auto Load Relief) (%) Mean Ah 1258.35 18.95 8.76 17.14 13.54 Standard deviation 141.14 1.17 0.89 1.37 4.30 11.2% 6.2% 10.2% 8.0% 31.7%

Example 7 Preparation with a Plasma Reactor.

Carbon nanofiber nets are produced by using plasma instead of burning carbon gas. The gaseous plasma used is nitrogen (N2) at 60 kW, with an initial plasma flow rate of 12 Nm ³ /h. The flow rate of argon is set at 0.6 Nm ³ /h. The flow rate of the starting materials (emulsion) is set at 2.5 kg/h. GC measurements are made to monitor H2 and carbon conversion progress. The injection temperature is set at 1400°C, the approximate residence time is 4 seconds. The collected material has a density of 0.13 g/cm ² and shows the presence of carbon nanofiber networks observed by SEM and TEM, see figures. The average fiber diameter was determined to be 70 nm, while the length between knots was 5-10 fiber diameters.

Claims (12)

1. A method for producing networks of crystalline carbon structures in a carbon black furnace reactor 3 comprising a reaction zone 3b and a completion zone 3c by injecting a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles into a reaction zone 3b having a temperature above 600°C and up to 3000°C, with the formation of networks e of crystalline carbon structures, moving the networks e to the completion zone 3c and abrupt cooling or suspension of the formation of networks of crystalline carbon structures in the completion zone by injecting water d, and the oil phase in the emulsion is an aroma - 11 042394 tic and/or aliphatic and contains at least 50 wt.% compounds C14 or higher, relative to the total weight of the oil phase. 2. The method according to claim 1, wherein the reactor 3 further comprises a combustion zone 3a, wherein the combustion zone 3a, the reaction zone 3b, and the termination zone 3c are located along the axis of the reactor 3, and wherein the method further comprises obtaining a hot exhaust gas stream a1 in the combustion zone by combustion fuel in oxygen-containing gas b and passing the exhaust gases a1 from the combustion zone 3a to the reaction zone 3b, spraying a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles in the reaction zone 3b containing hot exhaust gases, carbonizing the emulsion at a temperature above 600 °C to 3000°C and quenching or stopping the reaction in the completion zone 3c by injecting water d to obtain networks of crystalline carbon structures e. 3. The method according to any one of the preceding claims, wherein the temperature in zone 3b of the reactor is above 1100 and up to 2000°C. 4. The method according to any one of the preceding claims, wherein the emulsion contains at least 1 mM metal catalyst nanoparticles. 5. The method of claim 4, wherein the metal catalyst nanoparticles have an average particle size between 1 and 100 nm. 6. A network of crystalline carbon structures obtainable by the method of any one of the preceding claims, wherein the carbon structures are chemically bonded to each other by a variety of compounds, including Y and H compounds, where the structures have an average thickness of 1-400 nm and/or an average length in the range of 100-10000 nm and/or where the structures have an average aspect ratio of length to thickness of at least 2. 7. Mesh according to claim 6, wherein the structures have an average thickness between 5 and 100 nm and/or an average length between 100-5000 nm. 8. A composite containing nets of carbon structures according to any one of claims 6, 7, additionally containing one or more thermoplastic and heat-shrinkable polymer resins, to impart mechanical strength, electrical conductivity or thermal conductivity to the polymer-based composite, and where the nets are in an amount in the range 1-70 wt.% relative to the total weight of the polymer in the composite. 9. Composite according to claim 8, wherein the networks are in an amount between 20 and 40% by weight, based on the total weight of the polymer in the composite. 10. The composite of claim 9 having an E value of modulus increasing with network concentration as measured according to ISO 527. 11. A method for semi-continuous production of networks of crystalline carbon structures in a reactor 3, wherein a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles is injected from the top of the reactor 3 by spraying using an aerosol inlet 4 to produce an aerosol, and where the networks e is formed at an elevated temperature between 700-1200° C. and deposited at the bottom of the reactor, and where the elevated temperature is obtained using pyrolysis or by combustion, the oil phase in the emulsion being aromatic and/or aliphatic and containing at least 50 wt. compounds C14 or higher, relative to the total weight of the oil phase. 12. A method for producing networks of crystalline carbon structures in a reactor 3, where a water-in-oil microemulsion or a bicontinuous microemulsion c containing metal catalyst nanoparticles is injected from the top of the reactor 3, where the reactor is a thermal carbon black reactor, by spraying using an inlet 4 for an aerosol to produce an aerosol, and where the nets e are formed at an elevated temperature between 700-1200° C. and deposited at the bottom of the reactor, and where the elevated temperature is obtained by an initial combustion step using a heat source inside the reactor using air or oxygen, and where the emulsion is injected exclusively under pyrolysis conditions, and the oil phase in the emulsion is aromatic and/or aliphatic and contains at least 50 wt.% compounds C14 or higher, relative to the total weight of the oil phase.