Classifications

• • 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
  • C01B32/182—Graphene
  • C01B32/184—Preparation
• • 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
  • C01B32/182—Graphene
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2204/00—Structure or properties of graphene
  • C01B2204/04—Specific amount of layers or specific thickness

Definitions

• the present disclosure generally relates to the technical field of synthesis of graphene, synthetic graphite, and other carbon allotropes.
• graphene rather refers to a class of nanomaterials that includes; nanoplatelets (GNP), few-layer graphene (FLG), single-layer graphene (SLG), multilayer graphene (MLG), graphene oxide (GO), reduced graphene oxide (RGO), etc.
• GNP nanoplatelets
• FLG few-layer graphene
• SSG single-layer graphene
• MLG multilayer graphene
• GO graphene oxide
• RGO reduced graphene oxide
• FIG. 1 shows a basic process flow and system embodiment
• FIG. 2 illustrates a reaction vessel embodiment under the present disclosure
• FIG. 3 shows a detailed cross sectional view of the reaction vessel wall
• FIG. 4 shows a modified reaction vessel embodiment incorporating a vortex
• Figs. 5A-5N show SEM images of the sample (ER-01) treated at 900-950°C using unrecyclable plastics (HDPE, PET, PP, Styrene, PVC) and tires (waste plastics) as a carbon precursor and aluminum alloys as catalyst;
• unrecyclable plastics HDPE, PET, PP, Styrene, PVC
• tires waste plastics
• Figs. 6A-6N show TEM images of the sample (ER-01) treated at 900-950°C using unrecyclable plastics as carbon precursor and aluminum alloys as catalyst. Images (j) and (n) show diffraction results (SAED) of the graphene sheets; [00019] Fig. 7 shows a Raman spectra of sample ER-01 treated at 900-950°C using waste plastic as carbon precursor and aluminum alloy as catalyst;
• Fig. 8 shows Thermal Gravimetric (TGA) results of sample ER-01 in synthetic air
• Fig. 9 shows TGA results of sample ER-01 in argon
• FIG. 10 shows XPS spectra of carbon for sample ER-01
• FIGs. 11A-11H show SEM images of the sample ER-02 treated at about 900-1100°C using natural gas as carbon precursor and aluminum alloy as catalyst;
• Fig. 12 shows SEM mapping images of the sample ER-02 treated at about 900-1100°C using natural gas as carbon precursor and aluminum alloy as catalyst;
• Figs. 13A-13F show TEM images of the sample ER-02 treated at 900 to 1100°C using natural gas as carbon precursor and an aluminum alloy as catalyst;
• Fig. 14 shows a Raman spectrum of sample treated at about 900-1100°C using natural gas as carbon precursor and aluminum alloy as catalyst;
• FIG. 16 shows SEM mapping of the sample ER-03 treated at about 900- 950°C using HDPE as carbon precursor and aluminum alloy as catalyst;
• Fig. 17 shows the EDS spectrum of the analyzed area
• Figs. 18A-18C represent the EDS mapping of carbon, oxygen, and sulfur
• Fig. 19 shows the Raman spectrum of sample treated at about 900-950°C using HDPE as carbon precursor and aluminum alloy as catalyst;
• Fig. 20 shows TGA results of sample ER-03
• Fig. 21 shows a method embodiment under the present disclosure.
• Fig. 22 shows a method embodiment under the present disclosure.
• Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges.
• the present disclosure provides various processes and systems to recycle plastics, electronics, munitions, coal, coke or propellants and/or produce graphene, graphite and other carbon allotropes.
• Various embodiments may utilize a molten aluminum or molten aluminum alloy bath.
• Certain embodiments utilize a molten aluminum bath as the reactant.
• the ground feedstock may be introduced below the surface of the molten aluminum bath and react with the aluminum to decompose the feed stock.
• elemental carbon, sulfur, copper, iron, and rare earth and heavy metals and molecular hydrogen, nitrogen, methane, and other hydrocarbons can be removed from the molten bath.
• the products can be sold and the nitrogen is either vented to the atmosphere or captured.
• Certain embodiments may provide one or more of the following technical advantages. Advantages can include (re)capture of a variety of materials, all of which can be reused and/or sold. This can make the described embodiments a truly “green” and zero waste solution.
• Certain embodiments utilize a molten metal as the primary reactant, such as aluminum or an aluminum alloy bath.
• the aluminum can also be alloyed with other elements including, but not limited to, zinc, iron, copper, silicon and calcium. Other metals and metal alloys such as calcium and silicon are also envisioned.
• the flue gas stream which contains oxygen containing greenhouse gases produced by combustion processes, is passed through the aluminum alloy bath to remove the oxygen-containing gases from the flue gas stream.
• excess heat can be generated and can be used to facilitate other processes such as cogeneration of power.
• the excess heat generated by the process is a function of the makeup of the carbon precursor feedstock or gases in the feed.
• the feed stock contains other compounds, those compounds can also be decomposed or captured.
• the process will produce an aluminum salt, in this case aluminum chloride.
• the present disclosure also provides methods and systems for capturing heavy metals, such as, but not limited to mercury or rare earth metals, which are often found in consumer electronics or munitions.
• the molten metal bath breaks down the metal compounds as they are introduced into the molten metal bath.
• the heavy metals settle to the bottom of the reaction vessels and are removed from the reaction vessel. While some aluminum may be entrained in the heavy metals that are removed from the bottom of the reaction vessel, the aluminum can be removed and refined and the heavy metals can be captured.
• FIG. 1 shows one possible embodiment 100 under the present disclosure.
• ground material is introduced below the surface of the molten metal bath 103 using an injection feed system 101 through feed line 102.
• the elemental material such as carbon, sulfur and the like, is captured 104, less dense secondary compounds are removed from the surface of bath 105, and denser secondary compounds are removed from the bottom of the bath 106. While this has been described as a method to recycle plastics, electronics, munitions or propellants, use of this method to recycle other organic compounds, such as, but not limited to rubbers, coal, coke, oils and tars are also contemplated.
• FIG. 2 shows a further possible process flow embodiment 200. While the process described discusses processing recycling plastics, electronics, munitions, propellants, and other materials can be processed.
• the ground feed stock is introduced into the treatment process through blower feed line 211.
• Blower 210 which may be another type of injector, is used to inject the ground feed stock into reaction vessel 220 through injection line 212.
• Injection line 212 introduces the ground feed stock, which is entrained in an inert gas such as nitrogen, or an active gas such as but not limited to Hydrogen, propylene, natural gas, below the surface of the molten aluminum compound 226. Injection line 212 must be sufficiently below the surface of the molten aluminum compound 226 to allow for sufficient mixing.
• the heavy products of the reaction typically the heavy metals described above will settle out in the reaction vessel.
• the reaction vessel typically has a sloped bottom, however other designs such conical bottoms and the like can be utilized.
• Collection lines 223, 224, and 225 allow for heavy metals of different densities to be removed.
• the heavy products can be continuously removed or a batch removal process can be used.
• Reaction vessel 220 also includes an aluminum feed line 221, which is used to supply additional aluminum compound to replace that consumed by the reaction with the ground feed stock. Additional heat may be required during start-up, for example.
• Heater 227 is provided for this purpose. Heater 227 can be any type of heater, including radiative, inductive, and convective. For example, heater 227 would be a microwave heater or a radio frequency heater wherein the frequency is tuned for the metal alloy used.
• the heat generated by the process is preferably removed.
• Section A which is shown in more detail in Figure 3, shows one way the heat can be removed from the process.
• the reaction vessel 220 is lined with a refractory material 310, which protects the vessel wall 320.
• Cooling plate 330 is attached to the vessel wall 320 and cooling media (e.g., air, water, other fluid)is circulated in the channels created between the cooling plant 330 and the vessel wall 320.
• Insulation 340 surrounds the cooling plate to maximize heat recovery, as well as for safety purposes.
• FIG. 2 a steam turbine electric generation process is represented.
• the cooling water is introduced thorough cooling feed 228.
• the steam generated is then sent via steam line 229 to steam turbine 232.
• the steam passes through the turbine and as it condenses, turns the turbine blades of turbine 232.
• Turbine 232 is coupled to generator 231.
• this steam turbine-electric generator process is well known in the art. And any steam turbine-electric generator process could be utilized.
• the reaction can also produce elemental carbon, elemental sulfur, molecular nitrogen and molecular hydrogen, or other materials. These can be removed from the reaction vessel using blower 250. Blower 250 can e.g., pull high temperature elemental carbon, elemental sulfur, molecular nitrogen and molecular hydrogen from the reaction vessel 220 through heat exchanger feed line 241 into heat exchanger 240. Heat exchanger 240 will then cool this material to enable further processing. Any hydrocarbons that are produced may also be condensed in heat exchanger 240. These liquid hydrocarbons can be collected for further use or sale.
• Heat exchanger 240 can be any heat exchanger, however in the preferred embodiment, heat exchanger 240 is a forced air heat exchanger, however other heat exchangers, are also envisioned.
• the process stream then leaves the heat exchanger through line 242 and passes through blower 250 and blower discharge line 252 into two cyclone separators.
• the first separator 260 separates out carbon from process stream.
• the carbon is collected though separation line 263.
• the remaining process stream proceeds to the second separator 270, which separates out sulfur from the process stream.
• the sulfur may be removed using a cold finger as the stream is cooled to less than 444 degrees Celsius.
• the sulfur is collected through separation line 273.
• the remaining process stream which may include gaseous nitrogen and hydrogen, is then separated in cryo unit 280. In this unit, the gas stream is cooled further and to allow the components to be separated.
• FIG 4 shows a modified process flow 400 using a vortex entry.
• the modified process enables recycling of e.g., plastics, electronics, coal, coke, munitions or propellants.
• the ground feed stock is introduced into the treatment process through line fed by a vortex 402.
• the vortex 402 is formed within a ceramic bowl 415 by pumping in molten aluminum or aluminum alloy.
• the molten aluminum or aluminum alloy may be added through a new aluminum input line 404, or it may be recirculated from the aluminum bath using a pump 406.
• the ground feed stock (which may include any of the materials above that need to be recycled) may then be introduced into the ceramic bowl 415 through a gravity feed 405.
• the ground feed stock mixes with the molten aluminum or aluminum alloy and the mixture is pulled to the bottom of the bowl from the rotation of the vortex 402.
• the bottom of the ceramic bowl 415 may have a connecting line 408 to the aluminum bath, and the mixture of ground feed stock and molten aluminum or aluminum alloy enters the aluminum bath from the connecting line 408.
• Other aspects of the modified process flow 400 are similar to that shown with the flow in Figure 2.
• the vortex entry illustrated in Figure 4 allows for some benefits over other injection systems.
• the vortex allows better mixing of the ground feed stock with the molten aluminum or aluminum alloy, which allows the recycling reactions to occur more efficiently.
• the temperature of the mixture has an opportunity to equalize, and the temperature may be relatively close to the temperature of the molten aluminum within the bath. Accordingly, there is less localized cooling, and a more consistent temperature gradient, at the entry injection point when the vortex entry is used.
• FIG. 1 A doping process may occur as result of presence of oxygen during the graphene synthesis.
• the system may be designed to vary the residence time of the carbon precursor to allow for the synthesis of various graphite or graphene structures.
• Various different metal catalysts e.g., Mg, Fe, Co
• Embodiments of the reactor are currently designed to operate at relatively low pressures of about 3-5psi gauge. It is envisioned that the reactor may be run at higher pressure up to several atmospheres.
• a carrier gas may or may not be used during the process.
• This carrier gas can be any of the short chain hydrocarbons, nitrogen, or hydrogen.
• An inert gas may or may not be used during the process.
• nitrogen is used in some example embodiments as an inert gas, but argon or the other inert gases can be used.
• Hydrogen may or may not be a byproduct of the reaction. Further micronization, pulverizing or jet milling might be used to fine process any product materials and outputs.
• Example 1 For Example 1, a mix of unrecyclable grinded plastic waste was inserted into the reactor with an aluminum alloy. An inert gas (e.g., nitrogen) was used as carrier to transport the graphene from the reaction chamber to the collecting container. The temperature range at the reaction chamber was kept between 600°C to 950°C.
• the sample ER-01 included unrecyclable plastics (e.g., HDPE, PET, PP, Styrene, PVC) and tires (waste plastics). These served as a carbon precursor and aluminum alloys were used as catalyst.
• unrecyclable plastics e.g., HDPE, PET, PP, Styrene, PVC
• tires waste plastics
• Figures 5A-5N show scanning electron microscopy (SEM) images of the sample ER-01 after manual grinding.
• the sample was dispersed in methanol, sonicated by an ultrasound bath for 5 minutes, and drop-casted on a Si/SiO2 wafer.
• the images show particles aggregates above 5 pm whereas higher resolution images (x250,000) show small flakes below 100 nm.
• Figure 6A-6N show transmission electron microscopy (TEM) images of graphene sheets and ribbons (ER-01) after dispersion in methanol for 10 minutes by ultrasonicating bath. A drop of the sample was deposited on a nickel TEM grid coated with lacey carbon.
• Figures 6A-6N show graphene flakes (images A-F) and sheets (images G-N). The graphene sheets have up to three turbostratic layers according with Selected Area Electron Diffraction SAED (images J, N).
• Figures 8 and 9 show thermal gravimetric analysis (ER-01) for air and argon. Thermal gravimetric analysis was performed using synthetic air, using ⁇ 4 mg ramp from 30°C to 950°C, heating rate of 10°C/minute. One analysis was done in synthetic air while the other was done in argon.
• the lines in Figure 8 show the thermal decomposition profile of graphene (sample ER-01) in air. The temperature of degradation of the graphene starts at about 55O°C whereas the complete degradation happens at about 700°C. There is almost total degradation of the sample.
• the line in Figure 9 shows the thermal decomposition profile of graphene (sample ER- 01) in argon. The temperature of degradation of the graphene starts at about 720°C whereas the end of the degradation happens at about 950°C There is a residue of 70% after the temperature treatment.
• Example 2 natural gas was inserted into the reactor with aluminum alloy.
• An inert gas e.g., nitrogen
• the temperature range at the reaction chamber was kept between 900°C to 1100°C.
• the total reaction time was 120 min. Variations of the synthesis regarding the temperature I reaction time are as it follows, initial 60 minutes at temperature range of 900°C to 950°C, followed by a ramp up to ⁇ 1100°C.
• the material was kept at temperature plateau of ⁇ 990°C to 1100°C for 30 minutes. After that the temperature was kept between 900°C to 920°C for 30 minutes.
• Figures 11 A- 11H show SEM images of sulfur-graphene flakes from sample ER-02.
• the sample was dispersed in methanol, sonicated by ultrasound bath for 5 minutes, and drop-casted on a Si/SiO2 wafer.
• the results show graphene flakes, and nanorods.
• Figure 12 shows SEM mapping images of sulfur-graphene flakes from sample ER-02.
• the sample was dispersed in methanol, sonicated by ultrasound bath for 5 minutes, and drop-casted on a Si/SiO2 wafer.
• the mapping was obtained according with the initial EDS spectrum of the area obtained from image 13A.
• Figure 12 shows the image of the area for mapping.
• Figures 13A-13F show TEM images of sulfur-graphene from sample ER- 02. These TEM images of the sample ER-02 were collected after dispersion in methanol for 10 minutes by ultrasonicating bath for 10 minutes. A drop of the sample was deposited on a nickel TEM grid coated with lacey carbon. Figures 13A-13F show graphene flakes and small particles of carbon/sulfur.
• Figure 14 shows Raman spectroscopy results of sulfur-graphene for sample ER-02.
• the Raman spectrum was acquired using a 532 nm laser line, acquisition time of 10 seconds, 10 to 15 acquisitions.
• the spectrum shows peaks from 161 cm-1 to 434 cm-1 which represent the contributions of stretching modes (v) related to -S-S-, polymerized -S-S-, as well as nanorods (ZnS?).
• the peak at 654 cm-1 represents (v) of -C-S- bond.
• the D band at 1343 cm-1 which corresponds to a shifted breathing mode of k point phonons of Alg symmetry.
• the D band arises from certain defects such as vacancies, grain boundaries, etc.
• the G band at 1600 cm-1 corresponds to the E2g phonon of the sp2 C atoms.
• Two other bands were observed at 2660 and 2890 cm-1 which represent the 2D band and S3 band respectively.
• the 2D band is observed to be broadened, attributed to the fact that the prepared graphene contains few layers with some defects.
• Example 3 high density polyethylene (HDPE) was inserted into the reactor with aluminum alloy.
• An inert gas e.g., nitrogen
• HOPG highly oriented pyrolytic graphite
• Figures 15A-15I show SEM images of highly oriented pyrolytic graphite (HOPG) like from sample ER-03.
• the sample was dispersed in methanol, sonicated by ultrasound bath for 5 minutes, and drop-casted on a Si/SiO2 wafer.
• the HOPG like material showed graphitic flakes embedded in round graphitic structures.
• Figures 16, 17, and 18A-18F show SEM mapping images of HOPG like material from sample ER-03.
• the sample was dispersed in methanol, sonicated by ultrasound bath for 5 minutes, and drop-casted on a Si/SiO2 wafer.
• the mapping was obtained according with the initial EDS spectrum of the area obtained from image 23(a).
• Figure 16 shows the image of the area to be mapped.
• Figure 17 shows the EDS spectrum of the analyzed area.
• Figures 18A-18C represent the EDS mapping of carbon in Figure 18A, oxygen in Figure 18B, and sulfur in Figure 18C.
• Figure 19 shows Raman spectroscopy results of HOPG-like for sample ER- 03.
• the Raman spectrum was acquired using a 532 nm laser line, acquisition time of 10 seconds, 10 -15 acquisitions.
• the spectrum shows a D band at 1358 cm-1.
• the D band arises from certain defects such as vacancies, grain boundaries, etc.
• the G band at 1601 cm-1 corresponds to the E2g phonon of the sp2 C atoms.
• the peaks above 2500 cm-1 correspond to the spectral signature of highly oriented pyrolytic graphite (HOPG) like structure.
• HOPG highly oriented pyrolytic graphite
• Figure 20 shows a thermal gravimetric analysis of sample ER-03.
• the thermal gravimetric analysis was performed using synthetic air, using ⁇ 4 mg ramp from 30°C to 1000°C, heating rate of 10°C/minute.
• Figure 20 shows the thermal decomposition profile of sample ER-03 in air.
• the temperature of degradation of the graphene is at about 555°C. According with the data above, 96.21% of the sample decomposes at 555°C. A small degradation below 2% is observed in about 200°C which can be attributed to equipment calibration or amorphous carbon.
• Method 2600 comprises a method for manufacturing carbon material.
• Step 2610 is mixing a carbon precursor with a catalyst in a controlled oxygen free environment, where the reaction is carried-out at a range from about 600°C to 1400°C.
• Method 2600 can comprise multiple variations and embodiments and/or additional and/or alternative steps.
• Method 2800 comprises a method of synthesizing carbon.
• Step 2810 is mixing a feed stock with molten aluminum.
• Step 2820 is injecting the molten aluminum and feed stock mixture into a reaction vessel containing further molten aluminum, wherein the injection occurs below the surface of the molten aluminum in the reaction vessel.
• Step 2830 is reacting the feed stock with the molten aluminum, such that one or more carbon-containing products are formed.
• Method 2800 can comprise multiple alternative embodiments with additional or alternative steps.
• the terms “approximately,” “about,” and “substantially,” as used herein, represent an amount or condition close to the specific stated amount or condition that still performs a desired function or achieves a desired result.
• the terms “approximately,” “about,” and “substantially” may refer to an amount or condition that deviates by less than 10%, or by less than 5%, or by less than 1%, or by less than 0.1%, or by less than 0.01% from a specifically stated amount or condition.
• references in the specification to "one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
• first and second etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments.
• the term “and/or” includes any and all combinations of one or more of the associated listed terms.
• systems, devices, products, kits, methods, and/or processes, according to certain embodiments of the present disclosure may include, incorporate, or otherwise comprise properties or features (e.g., components, members, elements, parts, and/or portions) described in other embodiments disclosed and/or described herein. Accordingly, the various features of certain embodiments can be compatible with, combined with, included in, and/or incorporated into other embodiments of the present disclosure. Thus, disclosure of certain features relative to a specific embodiment of the present disclosure should not be construed as limiting application or inclusion of said features to the specific embodiment. Rather, it will be appreciated that other embodiments can also include said features, members, elements, parts, and/or portions without necessarily departing from the scope of the present disclosure.
• any feature herein may be combined with any other feature of a same or different embodiment disclosed herein.
• various well-known aspects of illustrative systems, methods, apparatus, and the like are not described herein in particular detail in order to avoid obscuring aspects of the example embodiments. Such aspects are, however, also contemplated herein.

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