Carbon catalyst separation

Abstract

A method for separating carbon material from a catalyst in a carbon generation process, such as a CARGEN process, is provided. The method includes preparing a solution, mixing the solution with both carbon and a catalyst to form a supernatant mixture and a precipitate, and filtering the supernatant mixture from the precipitate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to U.S. Provisional Patent Application No. 63 / 365,061, filed May 20, 2022, the entire contents of which are incorporated herein. Background Art

[0003] Catalysts are used with industrial processes such as natural gas reforming to convert organic compounds into synthesis gas (syngas), which is an important feedstock for the production of value-added chemicals. Carbon generation / production may occur in such industrial processes and carbon may form on the catalyst, resulting in catalyst deactivation. Therefore, a carbon catalyst separation process is needed to improve, for example, catalyst utilization and carbon generation / production and its recovery. Summary of the invention

[0004] The present disclosure generally relates to a carbon catalyst separation process and system. The processes and systems of the present disclosure are intended to improve existing processes, systems and equipment for separating carbon catalyst materials. As disclosed herein, for example, the present technology provides processes and systems that address common difficulties in carbon and synthesis gas production. According to one embodiment, higher carbon recoveries can be achieved through the carbon catalyst separation process. In addition, for example, the carbon catalyst separation process allows for the reuse of catalysts, which can minimize the cost of obtaining sometimes expensive catalyst materials.

[0005] In view of the present disclosure, and without limiting the scope of the present disclosure in any way, in one aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, a method for separating a carbon material from a catalyst in a carbon generation process includes preparing a solution, mixing the solution with a carbon material and a catalyst in a solid-liquid mixer to produce a supernatant mixture and a precipitate, and filtering the supernatant mixture from the precipitate.

[0006] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the carbon generation process comprises a CARGEN process.

[0007] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the catalyst is a material selected from the group consisting of lime dolomite, coal, and combinations thereof.

[0008] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution comprises hydrochloric acid and nitric acid.

[0009] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution comprises sulfuric acid and nitric acid.

[0010] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution comprises hydrochloric acid, nitric acid, and methanol.

[0011] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the maximum volume concentration of methanol is 50%.

[0012] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution comprises sulfuric acid and methanol.

[0013] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the maximum volume concentration of methanol is 50%.

[0014] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution comprises sodium hydroxide.

[0015] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution comprises sodium hydroxide and methanol.

[0016] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the maximum volume concentration of methanol is 50%.

[0017] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the volume concentration of the solution is 5% or less.

[0018] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the molar concentration of the solution is six or less.

[0019] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution is mixed with the carbon material and the catalyst at 50°C.

[0020] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution is mixed with the carbon material and the catalyst for three hours.

[0021] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution is mixed with the carbon material and the catalyst for ten minutes.

[0022] In another aspect of the disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the solution is mixed with the carbon material and the catalyst for one hour.

[0023] In another aspect of the present disclosure, which aspect may be combined with any other aspect described herein unless otherwise stated, the method for separating a carbon material from a catalyst for a carbon generation process further comprises mixing the solution with the carbon material and the catalyst by sonication to produce a supernatant mixture and a precipitate.

[0024] In another aspect of the present disclosure, which may be combined with any other aspect described herein unless otherwise stated, the method for separating carbon material from a catalyst for a carbon generation process also includes mixing the supernatant mixture with the carbon material and the catalyst in a solid-liquid mixer to produce a precipitate and filtering the supernatant mixture from the precipitate.

[0025] In another aspect of the present disclosure, which may be combined with any other aspect described herein unless otherwise stated, the method for separating carbon material from a catalyst for a carbon generation process further comprises mixing the supernatant mixture with the carbon material and the catalyst by sonication to produce a precipitate.

[0026] Additional features and advantages are described in and will be apparent from the following detailed description and accompanying drawings. The features and advantages described herein are not exhaustive, and in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the accompanying drawings and description. In addition, any particular embodiment need not have all of the advantages described herein, and each advantageous embodiment is expressly contemplated to be claimed separately. Furthermore, it should be noted that the language used in the specification is selected primarily for readability and instructional purposes, and does not limit the scope of the subject matter of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A process flow diagram depicting the operation of a carbon generating reactor (CARGEN) in accordance with the present subject matter is shown.

[0028] Figure 2 A method for enhancing CO according to the present invention is shown. 2 Process flow diagram for operation of a fixed dual reactor setup.

[0029] Figure 3 A process flow diagram depicting the operation of a solid carbon / catalyst recovery unit in accordance with the present inventive subject matter is shown.

[0030] Figure 4 The mixture exiting the mixer comprising supernatant and solid precipitate according to the inventive subject matter is illustrated.

[0031] Figure 5 A method of separating solid carbon from a catalyst according to the present inventive subject matter is illustrated.

[0032] Figure 6 Indicates the basis Figure 5 A method for separating solid carbon from a catalyst, which further comprises the step of recovering a supernatant mixture from the precipitate.

[0033] Figure 7 Indicates the basis Figure 6 A method for separating solid carbon from a catalyst, which also includes sonication and a further filtering step. DETAILED DESCRIPTION

[0034] The present disclosure generally relates to carbon catalyst separation. More specifically, according to one embodiment, the present disclosure relates to carbon catalyst separation required due to the generation / production of carbon on the catalyst used in industrial processes such as the CARGEN process, which is disclosed in, for example, US20230039945A1, WO2021125990A1, EP4076735A1, CN115279490A, US11591213B2 and AU2018249486B2, the entire contents of which are incorporated herein by reference.

[0035] CARGEN technology, previously disclosed in patents US11591213B2 and AU2018249486B2, represents a breakthrough in the field of natural gas reforming. The innovative process catalytically converts greenhouse gases such as natural gas and carbon dioxide into synthesis gas and solid carbon.

[0036] Synthesis gas, which mainly consists of hydrogen and carbon monoxide, is a key raw material for the production of various high-value chemicals. It should be noted that it plays an important role in the synthesis of hydrocarbon fractions such as liquid transportation fuels produced via Fischer-Tropsch synthesis, as well as methanol and dimethyl ether.

[0037] On the other hand, the solid carbon produced by the CARGEN process exists in different forms, including carbon nanotubes, carbon black, graphene, graphene oxide and graphite. Such solid carbon is an important precursor with a wide range of applications, such as making cement, rubber, reinforced polymers and concrete. In addition, for example, such solid carbon plays a key role in the electronics industry for the production of batteries, conductors, chips and various other electronic components.

[0038] The catalyst materials used in the CARGEN process disclosed in, for example, US20230039945A1, WO2021125990A1, EP4076735A1, and CN115279490A are specifically designed to provide high activity and selectivity for solid carbon formation, especially carbon in the form of carbon nanotubes, while maintaining long-term stability operation. The carbon nanotubes produced in the CARGEN process follow a tip growth mechanism, in which the catalyst material is at the tip of the growing carbon nanotube. Compared with the total amount of the catalyst material comprising the active metal phase and the support material, only a small part of the active metal phase is carried at the tip of the carbon nanotube, and the rest is retained in the body, serving as a site for synthesis gas production. After the carbon nanotubes are formed, it is necessary to separate the bulk catalyst material to recover and improve the purity of the produced carbon nanotubes. This article describes such a process for the carbon-catalyst separation process, which cooperates with the core principles of the catalyst and CARGEN technology.

[0039] In one embodiment, the carbon catalyst separation process involves the generation / production and recovery of high purity carbon materials (e.g., carbon nanotubes) while enabling catalyst recovery and recycling. By implementing this process, the production of high quality carbon materials (e.g., carbon nanotubes) is achieved, thereby promoting sustainability and resource efficiency within the CARGEN framework according to one embodiment.

[0040] For example, as disclosed in US11591213B2 and AU2018249486B2, the dual reactor system provides enhanced carbon dioxide utilization for chemical and fuel processes while ensuring CO 2 Fixation (e.g., using CO 2 The amount is less than the CO generated during this process 2 The first reactor is CH 4 +CO 2 The second reactor converts CH 4 +CO 2 In view of global concerns about greenhouse gas emissions, unlike conventional single-reactor reformer systems, this system enhances the total CO 2 Fixed. From CO 2 From a life cycle assessment ("LCA") and process integration perspective, the present subject matter helps to reduce CO emissions in methane reforming under fixed conditions. 2 Utilization simultaneously produces both solid carbon and syngas, the latter of which is an important feedstock for the production of a variety of value-added chemicals and ultra-clean liquid fuels.

[0041] For example, as disclosed in US11591213B2 and AU2018249486B2, the combined reforming process in the subject matter of the present invention aims to convert methane (or any other volatile organic compound) into CO 2 and optionally other oxidants such as O 2 , H 2 O or both react to produce synthesis gas.As provided herein, the optimum operating conditions of the temperature and pressure of the two reactors can be determined using thermodynamic equilibrium analysis.Any thermodynamically feasible reaction all shows that the reaction can be carried out, provided that the obstacles associated with the process are solved via the development of efficient catalysts and reactor orientation.

[0042] For example, as disclosed in US11591213B2 and AU2018249486B2, the subject matter of the present invention aims to optimize the operating conditions to make CO 2 This maximizes carbon formation in the first reactor, the carbon generation reactor (CARGEN), in the presence of limited oxygen to drive the reaction from heat. Since partial combustion or partial oxidation reactions are exothermic reactions, the CARGEN reactor involves CO 2 There are two main reactions for fixation. The first reaction involves the conversion of CO 2 to carbon. The second reaction involves partial oxidation using a portion of the methane (or any other VOC) for partial combustion to produce energy and other products. The energy provided by partial oxidation is more efficient than any other form of heat transfer because it is generated in situ in the process.

[0043] For example, as disclosed in US11591213B2 and AU2018249486B2, the CARGEN reactor can be operated at low temperature and low pressure / high pressure conditions, while the combined reformer (second reactor) can be operated at high temperature and low pressure / high pressure conditions. By taking advantage of the pressure and temperature swings between the two reactor units, the CO 2 Improvements are made in both fixed and dual reactor setups with reduced overall energy requirements. The inventive subject matter also utilizes the work and energy extraction processes associated with the pressure changes between the two reactors (such as turbines, expanders, etc.) to at least partially overcome the burden of pre-compression of the feed gas. Thus, the distinct unique synergy between the two reactors is beneficial in saving carbon credits, as well as improving the sustainability of the overall process. In addition to the syngas generated from the second reactor (the reforming reactor), the inventive process also produces solid carbon or carbonaceous material from the first reactor (the CARGEN reactor). This as CO 2The carbonaceous products produced as part of the fixation process have industrial value, wherein the carbonaceous products include, for example, carbon nanotubes, including multi-walled carbon nanotubes. In particular, the carbonaceous products can serve as starting materials to produce a number of value-added chemicals that can, for example, generate a large amount of revenue for a processing plant. Non-limiting examples of valuable chemicals include activated carbon, carbon black, carbon fibers, different grades of graphite, soil materials, etc. For example, as a total CO 2 As part of the capture process, the material can also be added to structural materials such as cement and concrete, as well as to road tars or wax preparations.

[0044] The present subject matter includes utilizing a dry reforming process to convert carbon dioxide into synthesis gas and carbon, as disclosed, for example, in US11591213B2 and AU2018249486B2. The present subject matter uses a dual reactor setup or system to enhance CO 2 The reaction scheme is divided into two processes in separate reactors connected in series. The first reaction aims to capture CO2 in the form of solid carbon, while the other reaction aims to convert CO 2 The present invention provides a method for converting CO into synthesis gas. 2 Fixed system approach.

[0045] For example, as disclosed in US11591213B2 and AU2018249486B2, the proposed scheme shows that CO is heated under autothermal low temperature conditions in the first reactor of a dual reactor arrangement. 2 Subsequent removal of solid carbon from the system (first reactor) enhances CO conversion in the second reactor by thermodynamically driving the reaction forward. 2 to synthesis gas. 2 From a Life Cycle Assessment (“LCA”) perspective, removing carbon from a system is highly beneficial.

[0046] There have been many studies devoted to developing a new type of catalyst category, which is intended to resist the formation of carbon on the catalyst surface, and thus protect the catalyst from deactivation, thereby reducing downtime. However, such catalysts are very expensive and affect the overall economy of the process. For example, the subject matter of the present invention disclosed in US20230039945A1, WO2021125990A1, EP4076735A1 and CN115279490A is more economical because it uses a catalyst in the first reactor instead, with the formation of carbon as the target or promoting the formation of carbon, such as the formation of carbon nanotubes, including the formation of multi-walled carbon nanotubes. As a non-limiting example, the catalyst may include a metal (including a metal oxide) (e.g., Fe, Ni, Co, etc. and their oxides) and supported on a catalyst support material such as alumina, titania, silica, zeolite, inorganic clay, etc., and as further described in, for example, US20230039945A1, WO2021125990A1, EP4076735A1 and CN115279490A, which are incorporated herein by reference as described above.

[0047] For example, as disclosed in US11591213B2 and AU2018249486B2, after the reaction in the first reactor, the solid carbon is filtered. The remaining product gas is fed to a second reactor (combined reformer) at a higher temperature dedicated to producing high-quality synthesis gas. Thermodynamic analysis of the results of operating the second reactor shows that no carbon is formed. Compared with the conventional reformer setting, this drives the reaction to be carried out at a much lower energy requirement (about 50 kJ less) and at a relatively lower temperature. A substantial increase in the synthesis gas yield ratio is also observed, which is not only beneficial to Fischer-Tropsch synthesis (which requires about 2:1 H 2 :CO ratio) and is beneficial for hydrogen production (which requires high H 2 :CO ratio).

[0048] For example, as disclosed in US11591213B2 and AU2018249486B2, in addition to obtaining a higher H 2 In addition to the advantage of a 10:CO ratio, a significant increase in methane and carbon dioxide conversion is observed at much lower operating temperatures. If a conventional reforming setup is used, such an effect would only be achieved at higher temperatures (almost 250°C). The advantage of removing carbon in the first reformer helps to significantly reduce the operating temperature in the second reactor. Therefore, for obtaining similar levels of methane and carbon dioxide conversion with zero carbon deposition, the subject matter of the present invention is much more energy efficient than a conventional single reactor setup operating at higher temperatures.

[0049] Figure 1A conceptual process flow diagram depicting the operation of the carbon generator (CARGEN) reactor or first reactor in a dual reactor system of the present teachings is shown. A compression unit 5 receives methane 1, carbon dioxide 2, oxygen 3, and steam 4 inputs. The compression unit 5 provides an output 6 of the compressed feed gas mixture to the CARGEN reactor 7. The CARGEN reactor 7 outputs unreacted gas 10, which enters a cyclone separator or electrostatic precipitator 12, producing unreacted methane 1, carbon dioxide 2, steam 14, and recovered solid carbon 13. The solid carbon / catalyst recovery unit 8 receives inputs of spent catalyst and solid carbon 11 from the CARGEN reactor 7 and recovered solid carbon 15 from the cyclone separator or electrostatic precipitator 12. The recovered catalyst is regenerated and fed back to the CARGEN reactor 6, and the carbon is discarded to a discarded carbon and catalyst collector 9.

[0050] Figure 2 is a non-limiting example of a dual reactor system according to the present subject matter. Figure 2 A compression unit 5 is shown receiving inputs of methane 1, carbon dioxide 2, oxygen 3, and steam 4. The compression unit 5 provides an output 6 of the compressed feed gas mixture to a CARGEN reactor 7. According to one embodiment, a work / energy recovery unit 12 may be provided. The CARGEN reactor 7 may provide an output 10 of unreacted gas at high pressure from the CARGEN reactor to the work / energy recovery unit 12.

[0051] The work / energy recovery unit 12 may then output the extracted work / energy 13 and provide a feed to the cyclone / electrostatic precipitator 14. The cyclone / electrostatic precipitator 14 provides an output of recovered solid carbon 15 to the solid carbon / catalyst recovery unit 8. The solid carbon / catalyst recovery unit 8 regenerates the catalyst (removes carbon from the catalyst) and provides the catalyst back to the CARGEN reactor 7. Any carbon and / or catalyst to be discarded is directed to the discarded carbon / catalyst collector 9. The cyclone / electrostatic precipitator 14 also outputs unreacted methane, carbon dioxide, and / or steam to the heat exchanger unit 16. From the heat exchanger unit 16, the high temperature and low pressure gas 17 is directed to the reformer reactor or second reactor 20. Additional feeds of methane, oxygen, and steam 18 are combined with the high temperature, low pressure gas from the heat exchanger unit 17 to serve as the feed gas 19 to the reformer reactor 20. The reformer reactor 20 then outputs a high temperature synthesis gas 21 to the heat exchanger unit 16. The heat exchanger unit 16 outputs a low temperature syngas 22 .

[0052] The carbon catalyst separation process of the present invention as shown by the solid carbon / catalyst recovery unit 8 can improve the quality of the carbon produced during the carbon generation process. The process of the present invention also provides a way to recover unused catalyst (e.g., unused CARGEN catalyst) present in the bulk phase for subsequent operating cycles. Since the carbon catalyst separation process of the present invention is an additional feature that can be used during carbon generation / production, the process of the present invention has the same commercialization potential as carbon generation / production processes such as the CARGEN process. For example, the carbon catalyst process of the present invention can improve the overall economic efficiency of the carbon generation / production process (e.g., the CARGEN process) by reducing the cost of catalyst materials that will be recycled back after separation. According to one embodiment, the method of carbon / catalyst separation is essential to, for example, the CARGEN process, and can achieve significant catalyst cost reductions while improving the quality of the carbon material produced.

[0053] According to one embodiment of the present disclosure, a method for separating a mixture of carbon and bulk catalyst associated with a CARGEN process is provided. The method enables recovery of loaded / unloaded catalyst from a carbon / catalyst mixture produced by a CARGEN process. In this regard, the carbon catalyst separation process of the present invention can enable the catalyst material to be recycled for subsequent operating cycles, such as during the operation of the CARGEN process. For example, the method utilizes a mixture of an acid or base and an organic solvent to remove active catalyst particles present in the bulk phase of a powder mixture. The method also optionally utilizes sonication technology to improve recovery. The present disclosure also provides a method for continuously operating a CARGEN reactor and a catalyst / carbon separation process according to one embodiment.

[0054] Figure 3 The solid carbon / catalyst recovery unit 8 is illustrated. The solid carbon / catalyst recovery unit 8 comprises a solid-liquid mixer 24 which receives input of spent catalyst and solid carbon 11 from the CARGEN reactor 7 and recovered solid carbon 15 from the cyclone separator or electrostatic precipitator 12 and prepared solution 23 .

[0055] The solution 23 prepared can be various chemical mixtures. The solution 23 can be prepared in any manner known to those of ordinary skill in the art. This can include mixing the components in a container. The following paragraphs identify some non-limiting exemplary solution 23 mixtures.

[0056] A first example of solution 23 includes a mixture of dilute acids including hydrochloric acid and nitric acid. The hydrochloric acid and nitric acid may be diluted by adding water to solution 23. In this example, the hydrochloric acid and nitric acid do not exceed 5% of the volume of the total solution 23.

[0057] A second example of solution 23 includes a mixture of sulfuric acid and water. By mixing sulfuric acid in water, the sulfuric acid is diluted. Sulfuric acid can be limited to 5% of the volume of the total solution 23.

[0058] A third example of solution 23 includes a mixture of dilute acid including hydrochloric acid and nitric acid and methanol. The mixture can also be diluted by adding water. The acid strength of the solution or the amount of hydrochloric acid and nitric acid added can be limited to 5% by volume. Finally, the amount of methanol does not exceed 50% of the volume of the total solution 23.

[0059] A fourth example of solution 23 includes a mixture of dilute acid including sulfuric acid and methanol. The mixture can also be diluted by adding water. The acid strength of the solution or the amount of sulfuric acid added can be limited to 5% by volume. Finally, the amount of methanol does not exceed 50% of the volume of the total solution 23.

[0060] A fifth example of solution 23 includes an alkaline sodium hydroxide and water mixture. Sodium hydroxide can produce a strongly alkaline solution with a molar concentration of up to 6.

[0061] A sixth example of solution 23 includes an alkaline mixture of sodium hydroxide, methanol, and water. Sodium hydroxide can produce a strongly alkaline solution with a molar concentration of up to 6. The amount of methanol does not exceed 50% of the volume of the total solution 23.

[0062] return Figure 3 , the solid-liquid mixer 24 receives inputs of spent catalyst and solid carbon 11 from the CARGEN reactor 7 and recovered solid carbon 15 from the cyclone separator or electrostatic precipitator 12 and the prepared solution 23. As further described below, the amount of each input is limited to optimally promote the reaction. The solid-liquid mixer 24 can be any type of mixer known to those of ordinary skill in the art, including but not limited to a tank mixer or a drum mixer. The mixing conditions of the solid-liquid mixer 24 are carefully controlled so that the temperature of the mixer 24 and the time spent in the reactor are predetermined by the method described below.

[0063] In one embodiment, the stream 25 from the solid-liquid mixer is directed to the filter 27. In another embodiment, the stream 26 from the solid-liquid mixer is directed to the acoustic processor 31 before filtering. The acoustic processor 31 further mixes the stream by applying ultrasonic waves to the mixture. In one embodiment, the acoustic processor 31 can be operated at a variable frequency optimized for the detachment of carbon. This allows the materials to interact more efficiently in the solution 23 to remove the catalyst material. The acoustic processor 31 can be any acoustic processor 31 known to those of ordinary skill in the art, including but not limited to a probe acoustic processor or a bath acoustic processor.

[0064] The overall mixing process of the solid-liquid mixer 24 and in one embodiment the acoustic processor 31 produces a stream comprising a supernatant 33 and a solid precipitate 34. This output stream is Figure 4 . The solid precipitate 34 is mainly carbon. The suspended supernatant 33 mainly contains the catalyst and compounds from the initially prepared solution 23. The supernatant 33 can be further processed to further extract the catalyst.

[0065] Once the mixing process is complete, the stream 25 or 32 including the supernatant 33 and the solid precipitate 34 enters the filter 27. The filter 27 can be any filter 27 known to those of ordinary skill in the art, including but not limited to membrane filtration, cyclone filtration, or electrostatic precipitator. The filtration conditions of the filter 27 are carefully controlled so that the temperature of the mixer 24 and the time spent in the reactor are predetermined by the method described below.

[0066] The recovered catalyst is regenerated and fed back to the CARGEN reactor 6, and the carbon is discarded to the discarded carbon and catalyst collector 9. Any carbon and / or catalyst to be discarded is directed to the discarded carbon / catalyst collector 9. From the filter 27, the precipitate 34 is directed to the discarded carbon / catalyst collector 9 as stream 30 or to the solid-liquid mixer 24 as stream 29. The precipitate 34 may pass through the sonicator 31 and the solid-liquid mixer 24 until no further catalyst can be recovered. The supernatant 33 stream is directed to the CARGEN reactor 7 as stream 28 or to the solid-liquid mixer 24 as stream 29.

[0067] therefore, Figure 5 A method 100 for separating solid carbon and catalyst is generally provided in the present invention. In a first step 102, a solution 23 is prepared. In a second mixing step 104, the solution 23 is mixed with inputs of spent catalyst and solid carbon 11 from a CARGEN reactor 7 and recovered solid carbon 15 from a cyclone separator or electrostatic precipitator 12 to produce a supernatant mixture 33 and a precipitate 34. In a third filtering step 104, the supernatant mixture 33 is filtered from the precipitate 34. Alternatively, in some embodiments, such as Figure 6 In the embodiment shown in , method 100 further includes step 108 of recycling supernatant mixture 33 to mixing step 104 .

[0068] Figure 7A method 100 is illustrated, which includes sonication. In a first step 102, a solution 23 is prepared. In a second mixing step 104, the solution 23 is mixed with inputs of spent catalyst and solid carbon 11 from a CARGEN reactor 7 and recovered solid carbon 15 from a cyclone separator or electrostatic precipitator 12 to produce a supernatant mixture 33 and a precipitate 34. This mixing step 104 is performed in a solid-liquid mixer 24. In a third filtering step 104, the supernatant mixture 33 is filtered from the precipitate 34. From the third filtering step 106, the supernatant mixture 33 may be recycled to the solid-liquid mixing step 104 or may instead be redirected to a sonication mixing step 110 to produce more supernatant mixture 33 and further produce precipitate 34 by mixing with the solution, carbon material, and catalyst by ultrasonic waves. In a fifth filtering step 104, the supernatant mixture 33 is filtered again from the precipitate 34. Finally, the supernatant mixture 33 may be recycled again by mixing it with carbon material and catalyst 108, 114. It may then be directed to the solid-liquid mixer 24 or the sonicator 31.

[0069] The following provides a further description of the carbon catalyst separation process of the present invention according to one embodiment. It should be understood that the carbon catalyst separation process of the present invention is not limited to the following process details, but may include one or more of the following process details and may be performed in any suitable manner and order: (1) a step of preparing a dilute acid mixture containing hydrochloric acid and nitric acid with an acid strength of no more than 5% by volume in water; (2) a step of preparing a dilute sulfuric acid mixture with an acid strength of no more than 5% by volume in water; (3) a step of preparing a mixture of a dilute acid containing hydrochloric acid and nitric acid and an organic solvent, methanol (MeOH), wherein the acid strength does not exceed 5% of the total volume and the methanol does not exceed 50% of the total volume; (4) a step of preparing a mixture of a dilute acid containing sulfuric acid and an organic solvent, methanol (MeOH), wherein the acid strength does not exceed 5% of the total volume and the methanol does not exceed 50% of the total volume; (5) a step of preparing a strong alkaline solution of sodium hydroxide (NaOH) with a strength of up to 6 mol / L; (6) a strong alkaline solution of sodium hydroxide (NaOH) and an organic solvent, methanol, wherein the alkaline strength does not exceed 6 mol / L and the methanol does not exceed 50% of the total volume; (7) a solid-liquid mixing step, wherein, for example, a 100 mg sample of the carbon / catalyst mixture is mixed with 10 mL 5 volume % hydrochloric acid and nitric acid solution at 50°C for 3 hours; (8) a filtration step to separate the supernatant from the solid carbon, and the supernatant can be further processed to recover valuable catalyst materials; (9) a solid-liquid mixing step, in which a 100 mg sample of the carbon / catalyst mixture is mixed with 10 mL of a 5 volume % sulfuric acid solution at 50°C for 3 hours; (10) a filtration step to separate the supernatant from the solid carbon, and the supernatant can be further processed to recover valuable catalyst materials; (11) a solid-liquid mixing step, in which a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of a 5 volume % hydrochloric acid and nitric acid solution and 5 mL of MeOH solution at 50°C for 3 hours; (12) a filtration step to separate the supernatant from the solid carbon, and the supernatant can be further processed to recover valuable catalyst materials; (13) a solid-liquid mixing step, in which a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of a 5 volume % sulfuric acid and 5 mL MeOH solution is mixed at 50°C for 3 hours; (14) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (15) a solid-liquid mixing step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of NaOH solution at 50°C for 10 minutes; (16) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (17) a solid-liquid mixing step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of NaOH solution and 5 mL of MeOH solution at 50°C for 10 minutes;(18) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (19) a solid-liquid mixing and sonication step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 10 mL of a 5 volume % solution of hydrochloric acid and nitric acid at 50°C for 1 hour; (20) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (21) a solid-liquid mixing and sonication step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 10 mL of a 5 volume % solution of sulfuric acid at 50°C for 1 hour; (22) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (23) a solid-liquid mixing and sonication step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of a 5 volume % solution of hydrochloric acid and nitric acid and 5 mL The MeOH solution is mixed at 50°C for 1 hour; (24) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (25) a solid-liquid mixing and sonication step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of a 5 volume % sulfuric acid solution and 5 mL of a MeOH solution at 50°C for 1 hour; (26) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (27) a solid-liquid mixing and sonication step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of a NaOH solution at 50°C for 10 minutes; (28) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials; (29) a solid-liquid mixing and sonication step, wherein a 100 mg sample of the carbon / catalyst mixture is mixed with 5 mL of a NaOH solution and 5 mL The MeOH solution is mixed at 50°C for 10 minutes; and (30) a filtration step to separate the supernatant from the solid carbon, wherein the supernatant can be further processed to recover valuable catalyst materials.

[0070] It should be understood that the process details mentioned above need not be followed in the exact order, but may be interchanged as desired and / or based on the operational, philosophical or guiding principles employed, when combined in an appropriate manner where applicable.

[0071] According to one embodiment, the carbon catalyst separation process of the present invention can be carried out in a continuous operation mode, as may be required during the process. The continuous operation mode can promote improvements in the quality of the carbon material. In one embodiment, the continuous operation mode is integrated into the CARGEN technology to continuously recover the catalyst material and further process it to mix with the supplemental catalyst. In one embodiment, the sonication system can be operated at variable frequencies that are optimized for the detachment of carbon materials (e.g., carbon nanotubes) so that the solvent and acid interact efficiently to remove the catalyst material. In one embodiment, the precipitate can be subjected to several stages of sonication and solvent separation until the catalyst can no longer be further recovered.

[0072] According to one embodiment of the carbon catalyst separation process of the present invention, the recovery of catalyst materials has been tested. For example, an inductively coupled plasma ("ICP") test was performed to determine the percentage of material recovery associated with the catalyst. For example, it was inferred that a maximum nickel metal recovery of 72% could be achieved using a mixed solution of dilute nitric acid and hydrochloric acid. A similar recovery of 72% nickel was also achieved with a sulfuric acid system. For aluminum support recovery, for example, a 6 mol / L NaOH solution sonicated for 1 hour provided a maximum recovery of 25%. It was also found that a sulfuric acid system could recover up to 11% of the aluminum as well as the above-mentioned 72% of the nickel. For both nickel and aluminum recovery, for example, a 5% dilute sulfuric acid system showed the desired recovery of both nickel and aluminum.

[0073] Scanning electron microscopy ("SEM") studies were performed on filtered carbon samples from all tests. Imaging was performed at 100 KX resolution at 500 nm particle range. This study was performed to evaluate whether the carbon catalyst separation treatment adversely affects the morphology of the carbon material (e.g., carbon nanotubes ("CNTs")). It was observed that the samples treated with NaOH significantly damaged the carbon material (e.g., CNT material). On the other hand, the carbon samples treated with sulfuric acid were observed to be highly intact, while the carbon samples treated with nitric acid showed some damage to the carbon material structure (e.g., CNT structure). From an imaging perspective, the sulfuric acid-based system provides ideal recovery without actually damaging the carbon material structure (e.g., CNT structure).

[0074] Raman analysis can be performed to determine the distortion factor (D / G ratio). This analysis enables the inference of carbon catalyst separation processes that do not affect the carbon material structure (eg, CNT structure).

[0075] The above methods may be performed in any order, and the above methods may include more, fewer, or other steps.

[0076] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the subject matter of the present invention and without diminishing its intended advantages. Accordingly, such changes and modifications are intended to be covered by the claims.

Claims

1. A method for separating carbon material from a catalyst in a carbon generation process, the method include: Prepare solutions; mixing the solution with the carbon material and the catalyst in a solid-liquid mixer to produce a supernatant mixture and a precipitate; as well as The supernatant mixture was filtered from the precipitate.

2. The method of claim 1, wherein the carbon generation process comprises a CARGEN process.

3. The method of claim 1, wherein the catalyst comprises a metal supported on a catalyst support material.

4. The method of claim 1, wherein the solution comprises hydrochloric acid and nitric acid.

5. The method of claim 1, wherein the solution comprises sulfuric acid and nitric acid.

6. The method of claim 1, wherein the solution comprises hydrochloric acid, nitric acid, and methanol.

7. The method of claim 6, wherein the maximum volume concentration of methanol is 50%.

8. The method of claim 1, wherein the solution comprises sulfuric acid and methanol.

9. The method of claim 8, wherein the maximum volume concentration of methanol is 50%.

10. The method of claim 1, wherein the solution comprises sodium hydroxide.

11. The method of claim 1, wherein the solution comprises sodium hydroxide and methanol.

12. The method of claim 11, wherein the maximum volume concentration of methanol is 50%.

13. The method of claim 1, wherein the volume concentration of the solution is 5% or less.

14. The method of claim 1, wherein the molar concentration of the solution is 6 or less.

15. The method of claim 1, wherein the solution is mixed with the carbon material and the catalyst at a temperature of up to 50°C.

16. The method of claim 15, wherein the solution is mixed with the carbon material and the catalyst for up to three hours.

17. The method of claim 15, wherein the solution is mixed with the carbon material and the catalyst for up to ten minutes.

18. The method of claim 15, wherein the solution is mixed with the carbon material and the catalyst for up to one hour.

19. The method of claim 1, further comprising mixing the solution with the carbon material and the catalyst by sonication to produce the supernatant mixture and the precipitate.

20. The method according to claim 1, further comprising: include: mixing the supernatant mixture with the carbon material and the catalyst in the solid-liquid mixer to produce the precipitate; as well as The supernatant mixture was filtered from the precipitate.

21. The method of claim 20, further comprising mixing the supernatant mixture with the carbon material and the catalyst by sonication to produce the precipitate.

22. The method of claim 1, wherein the method is operated in a continuous mode to facilitate improvement in the quality of the carbon material.

23. The method according to claim 22, further comprising: include: continuously recovering the catalyst to provide make-up catalyst; as well as The catalyst is mixed with the supplemental catalyst.

24. The method of claim 19, wherein the sonicator configured to mix the solution with the carbon material and the catalyst by sonication is operated at a variable frequency optimized for detachment of the carbon material so that efficient interaction of solvent and acid removes the catalyst material.

25. The method according to claim 1, further comprising: include: mixing the precipitate with the carbon material and the catalyst to produce the supernatant mixture and the filtered precipitate; as well as The supernatant mixture was filtered from the filtered precipitate.

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