Method and apparatus for purifying carbon product

Abstract

The application relates to a method and an apparatus for purifying a carbon product, in which the carbon product (2) is fed to a purification unit (3) in which the carbon product is treated by an acid to form a purified carbon product (4). The purified carbon product (4) is discharged from the purification unit (3). Further, an acid solution (5) is discharged from the purification unit (3), and the acid solution is recirculated.

Description

[0001] METHOD AND APPARATUS FOR PURIFYING CARBON PRODUCT

[0002] FIELD

[0003] The application relates to a method defined in claim 1 and an apparatus def ined in claim 12 for purifying a carbon product .

[0004] BACKGROUND

[0005] It is known different methods and devices for producing carbon, and also hydrogen, from hydrocarbons , such as methane . Further, it is known to produce solid carbon . Typically, methane splitting processes are used to form hydrogen and carbon .

[0006] Traditional methods of thermo-catalytic methane splitting focus on hydrogen production while the carbon, which represents of mass converted, is contaminated with metal catalyst . Typically, the carbon is oxidi zed with air or steam for regenerating the catalyst , and thus emitting CO2 and losing decarboni zation benefits .

[0007] OBJECTIVE

[0008] An obj ective is to alleviate the disadvantages mentioned above . In particular, the obj ective is to disclose a novel type of method for purifying a carbon product . Further, the obj ective is to disclose an improved process for methane decomposition or splitting . Further, the obj ective is to achieve an effective process for forming solid carbon products and / or hydrogen . Further, the obj ective is to provide an effective process to recover metals and catalyst .

[0009] SUMMARY

[0010] The method and apparatus are characteri zed by what are presented in the claims . The method for purifying a carbon product , wherein the carbon product is fed to a purification unit in which the carbon product is treated by an acid to form a purified carbon product , the purified carbon product and an acid solution are discharged from the purification unit , and the acid solution is recirculated .

[0011] The apparatus for purifying a carbon product comprises at least one purification unit in which the carbon product is treated by an acid to form a purified carbon product , means for discharging the purified carbon product and an acid solution from the purification unit , and at least one circulation device for recirculating the acid solution .

[0012] DETAILED DESCRIPTION

[0013] The method for purifying a carbon product comprises feeding the carbon product to a purification unit in which the carbon product is treated by an acid to form a purified carbon product , wherein the acid is a weak organic acid; discharging the purified carbon product from the purification unit ; and discharging an acid solution from the purification unit and recirculating the acid solution . Preferably metals , such as metals of catalyst , and the carbon product can be separated during the process , e . g . during or after a thermocatalytic methane splitting process .

[0014] An apparatus for purifying a carbon product comprises at least one purification unit in which the carbon product is treated by a weak organic acid to form a purified carbon product , means for discharging the purified carbon product from the purification unit , and means for discharging an acid solution from the purification unit , and at least one circulation device for recirculating the acid solution . In this context, the carbon product may be any carbon product comprising allotrope of carbon. In one embodiment, the carbon product comprises an allotrope of carbon, e.g. graphite, graphitic carbon, graphite fibers, graphene, carbon nanotube, carbon nanofiber, single wall carbon nanotubes, multiwalled carbon nanotubes, carbon nano onions, carbon nano shells, carbon micro shells, and / or amorphous carbon. In one embodiment, the allotrope of carbon comprises at least graphite, graphitic carbon, graphite fibers and / or graphene. In one embodiment, the allotrope of carbon comprises at least carbon nanofibers, carbon nanotubes and / or graphite. In one embodiment, the carbon product contains graphite and / or carbon black. In one embodiment, the carbon product is formed as a reaction product in the solid form. Preferably, the carbon product in solid form consists essentially of carbon, such as the allotrope of carbon. Further, the carbon product may contain metal or metal particles from the catalyst used in the process.

[0015] In the purification unit the carbon product is treated at least by the acid, and preferably metal is extracted from the carbon product to the acid solution. When the acid solution comprises metals, conductivity of the solution may be increased. In one embodiment, the purification unit comprises an electrochemical purification. In one embodiment, the purification unit is an electrochemical purification unit, in which the carbon product is treated by the acid to form the purified carbon product. In one embodiment, the electrochemical purification unit comprises at least one electrochemical purification device. In one embodiment, the electrochemical purification device comprises an electrolytic cell containing graphite rods. In one embodiment, the electrochemical purification device comprises at least one power supply. In one embodiment, the electrochemical purification device comprises a power supply capable of measuring voltage and current up to 20 A and 60 V. In one embodiment heat, preferably mild heat, is used or utilized during the purification in the purification unit. In one embodiment, the purification is carried out using the acid and the heat. In one embodiment, the purification is carried out using the acid and the heat, without an electrochemical purification. In one embodiment, the purification unit comprises a thermal bath. In one embodiment, the thermal bath is used at temperature of 20 - 100 °C. In one embodiment, the temperature is 20 - 100 °C during the purification. In one embodiment, the temperature is 40 - 80 °C, in one embodiment 50 - 70 °C, and in one embodiment 55 - 65 °C, during the purification. In one embodiment, the temperature is 20 - 60 °C, in one embodiment 20 - 40 °C, and in one embodiment 23 - 30 °C, during the purification, when the electrochemical purification is used. In one embodiment, the electrochemical purification is used when the purification is carried out at lower temperatures. In one embodiment, the carbon product is filtered after a metal extraction in the purification unit.

[0016] The acid used in the purification can be selected depending on the process and process conditions. In one embodiment, the acid is selected from the group consisting of a weak acid, etching solution, acid mixture or any combination thereof. Preferably, the acid is the weak organic acid. In one embodiment, the acid contains only C (carbon) , H (hydrogen) and 0 (oxygen) . Preferably, the acid comprises a limited oxidation of the carbon, preferably solid carbon, such as carbon product. In one embodiment, the acid is the etching solution. In one embodiment, the acid is the acid mixture. In one embodiment, the acid mixture comprises organic acid and mineral acid. In one embodiment, the acid consists of mainly the organic acid and further contain the mineral acid. Further, preferably the acid is selected so that the acid is environment-friendly and / or biodegradable. Using weak organic acids reduces an amount of water needed for washing the carbon product, such as solid carbon, compared to mineral strong acids. In one embodiment, the acid is a solution of formic acid, acetic acid, oxalic acid, citric acid or the like, or any combination thereof. The acid concentration may be selected depending on the acid selected. In one embodiment, the acid is formic acid. In one embodiment, the formic acid for the purification can be produced by using hydrogen formed in the production of carbon product, e.g. in splitting process, decomposition or thermocatalytic decomposition. Then, less energy is required for an acid production, and lower carbon footprint can be achieved. In one embodiment, the formic acid is formed by synthesizing by a direct hydrogenation of CO2, i.e. H2 + CO2 -> HCOOH.

[0017] In one embodiment, means for discharging the purified carbon product from the purification unit is selected from the group consisting of outlet, pipe, discharge pipe, tube, or any combination thereof. In one embodiment, means for discharging an acid solution from the purification unit is selected from the group consisting of outlet, pipe, discharge pipe, tube, or any combination thereof.

[0018] In one embodiment, the acid solution is supplied to a separation unit in which the acid solution is treated to separate an acid, such as an acid fraction. Further, in one embodiment, metal or metals can be separated from the acid solution in the separation unit. In one embodiment, the acid is separated by distilling in the separation unit to form an acid distillate. In one embodiment, the acid, such as acid fraction or acid distillate, is recirculated to the purification unit. In one embodiment, the apparatus comprises a separation unit in which the acid solution is treated to separate an acid, such as an acid fraction, and optionally metal ( s ) . In one embodiment , the separation unit comprises at least one separating device for separating at least the acid from the acid solution . In one embodiment, the apparatus comprises at least one circulation device for recirculating the acid to the purification unit . In one embodiment , the method comprises supplying the acid solution to a separation unit in which the acid solution is treated by distilling to separate an acid distillate , and recirculating the acid distillate to the purification unit . In one embodiment , the apparatus comprises a separation unit in which the acid solution is treated by distilling to separate an acid distillate , and at least one circulation device for recirculating the acid distillate to the purification unit . In one embodiment , the separation unit comprises a separating device in which the acid can be separated by distilling . In one embodiment , the separation unit comprises a distillation device, e . g . distillation column, as the separating device . In one embodiment, an acid such as fresh acid can be added to the recirculated acid fraction or acid distillate . In one embodiment , the apparatus comprises at least one acid feeder for feeding an acid such as fresh acid to the recirculated acid fraction or acid distillate . Then the fresh acid can be fed to the purification unit . In one embodiment, heat is supplied to the acid circulation . In one embodiment, the apparatus comprises at least one inlet for supplying heat to the acid circulation or to the recirculated acid fraction or acid distillate .

[0019] In one embodiment , metal compounds are separated from the acid solution in the separation unit . In one embodiment, metal formate, metal acetate, metal oxalate , citrate , other metal compound or any combination thereof are separated from the acid solution in the separation unit. In one embodiment, metal compounds are separated as a solid fraction.

[0020] In one embodiment, the acid solution is supplied to a precipitation unit. In one embodiment, the apparatus comprises at least one precipitation apparatus in the precipitation unit. Preferably, in the precipitation, the acid solution is treated by precipitating, and metal (s) or metal compound (s) , e.g. metal salts, hydroxides and / or carbonates, can be separated and / or recovered from the acid solution. The metal salts, hydroxides and carbonates can comprise metals, e.g. catalyst metals and optionally other metals. Suitable additive, such as a base, e.g. hydroxides or carbonates, can be added during the precipitation and / or to the precipitation apparatus for improving the precipitation and / or for neutralizing an acid. In one embodiment, the additive e.g. hydroxides or carbonates is added to the precipitation. In one embodiment, the method comprises supplying at least a part of the acid solution to the precipitation unit in which the acid solution is treated by precipitating. In one embodiment, the method comprises supplying at least a part of the acid solution to the precipitation unit in which the acid solution is treated by precipitating to separate metal salts, hydroxides and / or carbonates. In one embodiment, the acid solution is fed or circulated to the precipitation unit. In one embodiment, the apparatus further comprises the precipitation unit in which the acid solution is treated by precipitating to separate metal salts, hydroxides and / or carbonates. The precipitation unit may comprise one or more precipitation apparatus. In one embodiment, the precipitation unit comprises at least one precipitation apparatus and also at least one second separating device. In one embodiment, the second separating device is based on filtration. In one embodiment, the second separating device is a filtration device or filter. In one embodiment, metal salts, hydroxides and carbonates are separated in the second separating device. In one embodiment, metal salts, hydroxides and carbonates are separated in the precipitation apparatus. In one embodiment, the separated fraction is dried.

[0021] In one embodiment, the apparatus comprises at least one circulation device for circulating the acid solution from the purification unit, e.g. to the separation unit or to the precipitation unit. In one embodiment, the circulation device for circulating the acid solution from the purification unit, e.g. to the separation unit or to the precipitation unit, is selected from the group consisting of recirculation device, circulating device, pipe, pipework, pump, or any combination thereof. In one embodiment, circulation device for recirculating the acid, such as the acid fraction or the acid distillate, to the purification unit is selected from the group consisting of recirculation device, circulating device, pipe, pump, or any combination thereof.

[0022] In one embodiment, the method further comprises washing the purified carbon product. In one embodiment, the purified carbon product is washed, e.g. by water. The purified carbon product can be dried after washing. In one embodiment, the purified carbon product is washed and dried in a washing unit. In one embodiment, a metal leachate is separated from the purified carbon in the washing, such as in the washing unit. In one embodiment, the metal leachate comprises washing liquid, e.g. washing water. In one embodiment, the method comprises washing the purified carbon product to separate the metal leachate from the purified carbon. In one embodiment, washing liquid, e.g. water, used for washing the carbon product is supplied to form the metal leachate. In one embodiment, the apparatus comprises a washing unit for washing the purified carbon product to separate the metal leachate from the purified carbon. The washing unit may comprise one or more washing device for washing carbon product. Any suitable washing device, washer or scrubber or the like may be used as the washing device. In one embodiment, drying can be performed in the washing unit, e.g. in the washing device. In one embodiment, the apparatus comprises a drying device, e.g. after the washing device, for drying the purified carbon product.

[0023] In one embodiment, the metal leachate is supplied to the acid solution. In one embodiment, the metal leachate is supplied to the acid solution from the washing unit or washing device. In one embodiment, the metal leachate is supplied to the acid solution from the drying, such as from the drying device. In one embodiment, the apparatus comprises means for supplying the metal leachate to the acid solution. In one embodiment, the means for supplying the metal leachate may comprise pipe, tube, pump, other suitable device, or any combination thereof. In this context, the metal leachate comprises at least metals, e.g. catalyst metals and optionally other metals.

[0024] In one embodiment, the acid solution, which comprises the metal leachate, or its portion is fed to the precipitation unit in which the acid solution is treated by precipitating. In one embodiment, the acid solution, which comprises the metal leachate, or its portion is fed to the separation unit.

[0025] In one embodiment, the purified carbon product is further treated after the washing, such as after the washing unit, e.g. for upgrading the carbon product. In one embodiment, the purified carbon product is further treated in a further refinement unit. In one embodiment, graphite and / or carbon black is formed from the purified carbon product. In one embodiment, the apparatus comprises at least one refinement device for further treating the purified carbon product after the washing unit. In one embodiment, the refinement is based on electromagnetic separation, gravity separation, thermal upgrading, or any combination thereof.

[0026] In one embodiment, the carbon product formed in a methane splitting is purified to form the purified carbon product. In one embodiment, the carbon product formed in a thermal splitting, such as a thermal methane splitting, is purified to form the purified carbon product. In one embodiment, the thermal splitting is selected from the group consisting of a methane splitting, catalysed methane splitting, thermo-catalytic splitting, methane thermo-catalytic splitting, catalysed pyrolysis, catalysed hydrocarbon pyrolysis, catalysed methane pyrolysis, catalytic hydrocarbon decomposition, catalytic methane decomposition, thermocatalytic methane decomposition, chemical vapor deposition, other reaction, or any combination thereof.

[0027] The carbon product may contain catalyst from the process, e.g. the splitting process, in which the carbon product is produced. The catalyst means any catalyst, which comprises at least catalytic active material, e.g. metal or metal-based catalyst material. In one embodiment, the catalyst contains at least a metal or metals, e.g. metal alloy. The catalyst may contain one or more components. In one embodiment, the metal of the catalyst is selected from the group consisting of iron, manganese, nickel, copper, aluminium, titanium, cobalt, chromium, silicon, or an oxide thereof, or any combination thereof. In one embodiment, the catalyst comprises at least two catalytically active metals, wherein the two catalytically active metals are selected from the group consisting of iron, manganese, nickel, copper, aluminium, titanium, cobalt, chromium, silicon, and any combination thereof. In one embodiment, the catalyst comprises iron, manganese, nickel, copper, and / or aluminium. In one embodiment, the catalyst comprises at least iron. In one embodiment, the catalyst comprises a metal alloy. Thus, the carbon product may comprise the same metal (s) .

[0028] The metals can be removed from the carbon product by the purification, as presented. In one embodiment, the carbon product may comprise iron, calcium, magnesium, manganese, copper, nickel and / or aluminium as impurities, and at least a part of the impurities is removed from the carbon product in the purification process. In one embodiment, the carbon product comprises at least iron as the impurity, and the iron is removed from the carbon product in the purification process.

[0029] In one embodiment, the carbon product is purified such that the carbon product contains carbon of more than 85 % by weight, in one embodiment more than 90 % by weight, and in one embodiment more than 95 % by weight.

[0030] The separated metals and / or catalyst can be reused in the same process or in a desired process. In one embodiment, the separated metals or catalyst can be treated, e.g. by heating, regenerating and / or cleaning, before the reuse. In one embodiment, the separated metals are recovered and used in a suitable process to form a desired product. In one embodiment, the separated metals are used to form desired compounds. In one embodiment, the metals are used to form metal salts, hydroxides and / or carbonates. In one embodiment, the metals are used to form metal formates, acetates, oxalates, citrates or the like. In one embodiment, the separated metal or metals can be reused in a catalyst, i.e. metals are used to form the catalyst, or as a catalyst and / or as catalyst precursors. In one embodiment, the separated metals are reused as the catalyst or catalyst precursors.

[0031] In one embodiment, the method or apparatus is used in connection with a hydrocarbon decomposition or methane decomposition. In one embodiment, the method or apparatus is used in a methane splitting, catalysed methane splitting, thermo-catalytic splitting, methane thermo-catalytic splitting, catalysed pyrolysis , catalysed hydrocarbon pyrolysis , catalysed methane pyrolysis , catalytic hydrocarbon decomposition, catalytic methane decomposition, thermocatalytic methane decomposition, chemical vapor deposition, other reaction, or any combination thereof .

[0032] Thanks to the invention, an effective method and apparatus can be provided to purify carbon products . Metals , such as catalyst , can be separated from the carbon product during the purification process . The catalyst and metal can be recovered and reused or converted into valuable commercial products instead of producing waste . Further, the cleaned carbon product can be upgraded and refined, and valuable products can be produced . Thus , an effective method and process can be provided to produce solid carbon products and hydrogen . Further, the invention provides a sustainable method to purify the carbon product produced through methane splitting .

[0033] The invention offers a possibility to achieve purified carbon product with good properties easily . Further, the invention allows the purification of high carbon product volumes . The method and apparatus of the invention can be easily implemented as a post-treatment in actual carbon lines . Further, the purification of the carbon product is fast and environmentally friendly process . Especially, the carbon product can be purified environmentally friendly, when the organic acids are used .

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate some embodiments of the invention and together with the description help to explain the principle of the invention. In the drawings:

[0036] Fig. 1 shows a process for purifying a carbon product according to one embodiment, and

[0037] Fig. 2 shows test results relating to an effect of electricity and temperature on a carbon purity level (TC (%) ) .

[0038] EXAMPLES

[0039] In the purification process a carbon product (2) can be purified and metals can be recovered. Fig. 1 presents one example of the process.

[0040] The process of Fig. 1 comprises a purification of the carbon product (2) formed in a methane splitting (1) , such as a methane thermo-catalytic splitting reactor. Further, hydrogen (21) is formed in the methane splitting. The carbon product is fed from the methane splitting to a purification unit (3) in which the carbon product is treated by an acid, e.g. weak organic acid, etching solution or acid mixture, to form a purified carbon product (4) . According to one example, the acid can be a solution of formic acid, acetic acid, oxalic acid or citric acid. The purification unit can comprise an electrochemical purification, e.g. electrochemical purification device which comprises an electrolytic cell containing graphite rods. The purified carbon product (4) is discharged from the purification unit (3) . Also, an acid solution (5) is discharged from the purification unit (3) , and the acid solution is recirculated.

[0041] In pathway A, the acid solution (5) is fed to a separation unit (6) in which the acid solution is treated to separate an acid fraction (7) . Further, metal (s) or metal compound(s) (8) may be separated in the separation unit. According to one example, the separation unit comprises distillation, such as distillation device. Then the acid can be separated by distilling in the separation unit to form an acid distillate. In the distillation, the unreacted acid of the acid solution is evaporated. The acid fraction (7) , such as acid distillate, can be recirculated to the purification unit (3) , e.g. by at least one circulation device. Fresh acid may be added to the recirculated acid fraction (7) via an acid inlet (10) . Further, heat (9) may be supplied to the acid circulation. The metals comprising metals of the methane splitting catalyst may be recovered as solid metal compounds, e.g. metal formates, metal acetates, metal oxalates, citrates or other compounds. The organometallic salts may be precipitated and separated as a solid fraction, and an organometallic solution may be reused, e.g. as a catalyst precursor.

[0042] In pathway B, the acid solution (5) is fed to a precipitation unit (11) which comprises a precipitation apparatus. In the precipitation, the acid solution is alkalized to precipitate the solid fraction. Metal (s) or metal compound(s) (12) , e.g. metal salts, hydroxides and carbonates, can be separated and recovered. An additive (13) , e.g. hydroxides or carbonates can be added to the precipitation apparatus for raising pH and for improving the precipitation. Metal (s) or metal compound(s) (12) , e.g. metal salts, hydroxides and carbonates, may be separated by filtration. The separated fraction may be dried and reused, e.g. as a chemical by-product, or calcined and reused, e.g. as a catalyst precursor.

[0043] The purified carbon product (4) is washed in a washing unit (14) after the purification unit to form a washed purified carbon product (15) . The washing unit may comprise one or more washing device for washing carbon product. Further, the purified carbon product can be dried after the washing in the washing unit (14) or by a separate drying device. A metal leachate (16) , comprising at least catalyst metals and optionally other metals is separated from the purified carbon in the washing unit. The metal leachate (16) is supplied to the acid solution (5) . The acid solution (5) , which comprises the metal leachate, or its portion is fed to the precipitation unit (11) according to pathway B or to the separation unit (6) according to pathway A.

[0044] The washed purified carbon product (15) can be further treated after the washing unit (14) for upgrading the carbon product in a further refinement unit (17) , comprising at least one refinement device. The washed purified carbon product can be upgraded to form a desired product (18) , e.g. graphite or carbon black. A residue fraction (19,20) may be recirculated to the purification unit or to other use / process.

[0045] Example 1

[0046] In this example, the carbon product comprising graphite was purified in the purification unit by using a weak organic acid and heat. The carbon product comprised at least iron as an impurity.

[0047] In the first test, the carbon product was treated at temperature of 60 - 65 °C during the purification. In the second test, the carbon product was treated at temperature of 20 - 25 °C during the purification, in which also the electrochemical treatment was used.

[0048] It was observed that the iron can be removed from the carbon product during the purification and the high purity carbon product can be formed.

[0049] Example 2

[0050] In this example, the purification of the carbon product was examined.

[0051] The tests were performed such that 70 g of the carbon product, comprising graphitic carbon and further some metals, e.g. Fe, as impurity, was washed with formic acid using a 1 to 10 mass / volume ratio. The temperature was monitored using a normal thermometer while voltage and current were monitored with a laboratory power supply unit . Graphite rods were used as anode and cathode electrodes due to their conductivity and inertness . At the beginning of the experiment , the voltage was set to 20 V and kept constant throughout the experiments . The current and temperature values were measured every 10 min . An increase in the current correlated to the leachate increase in the solution was detected . The experiment was considered ready when a drop in the current was noticed .

[0052] Different tests were carried out at two target temperatures : 60 ° C and 25 ° C . The solution temperature is kept constant at 25 ° C to separate the temperature and electricity effects on the leaching extraction performance .

[0053] It was observed that the electricity improved a removal of metal from the carbon product at low temperature , such as at 25 ° C . Further, it was observed that the higher temperature improved a removal of metal from the carbon product . The effect of electricity and temperature on the carbon purity level ( TC ( % ) ) is presented in Fig . 2 .

[0054] Further, it was observed that the metals , e . g . Fe , can be removed effectively from the carbon product . For example , removal efficiency of Fe was 93 . 6 % .

[0055] The method and apparatus are suitable in different embodiments for purifying different carbon products . Further, the invention is suitable in different embodiments for producing improved carbon products .

[0056] The invention is not limited merely to the examples referred to above ; instead, many variations are possible within the scope of the inventive idea defined by the claims .

Claims

CLAIMS1. A method for purifying a carbon product, c h a r a c t e r i z e d in that the method comprises- feeding the carbon product (2) to a purification unit (3) in which the carbon product is treated by an acid to form a purified carbon product (4) , wherein the acid is a weak organic acid;- discharging the purified carbon product (4) from the purification unit (3) ; and- discharging an acid solution (5) from the purification unit (3) , and recirculating the acid solution.

2. The method according to claim 1, c h a r a c t e r i z e d in that the method further comprises: supplying the acid solution (5) to a separation unit (6) in which the acid solution is treated by distilling to separate an acid distillate, and recirculating the acid distillate to the purification unit (3) .

3. The method according to claim 1 or 2, c h a r a c t e r i z e d in that the method further comprises: washing the purified carbon product (4) to separate a metal leachate (16) from the purified carbon.

4. The method according to claim 3, c h a r a c t e r i z e d in that the metal leachate (16) is supplied to the acid solution (5) .

5. The method according to any one of claims 1 to 4, c h a r a c t e r i z e d in that the method further comprises: supplying at least a part of the acid solution (5) to a precipitation unit (11) in which the acid solution is treated by precipitating to separate metal salts, hydroxides and / or carbonates (12) .

6. The method according to any one of claims 1 to 5, c h a r a c t e r i z e d in that metal compounds (8) are separated from the acid solution (5) in a separation unit ( 6) .

7. The method according to any one of claims 1 to 6, c h a r a c t e r i z e d in that the purification unit (3) comprises an electrochemical purification.

8. The method according to any one of claims 1 to 7, c h a r a c t e r i z e d in that the carbon product(2) formed in a thermal splitting is purified to form the purified carbon product.

9. The method according to any one of claims 1 to 8, c h a r a c t e r i z e d in that the acid is selected from the group consisting of a weak acid, etching solution, acid mixture or any combination thereof.

10. The method according to any one of claims 1 to 9, c h a r a c t e r i z e d in that heat is used during the purification in the purification unit (3) .

11. The method according to any one of claims 1 to 10, c h a r a c t e r i z e d in that the purified carbon product is further treated after the washing.

12. An apparatus for purifying a carbon product, c h a r a c t e r i z e d in that the apparatus comprises at least one purification unit (3) in which the carbon product (2) is treated by a weak organic acid to form a purified carbon product (4) , means for discharging the purified carbon product from the purification unit, and means for discharging an acid solution (5) from the purification unit, and at least one circulation device for recirculating the acid solution.

13. The apparatus according to claim 12, c h a r a c t e r i z e d in that the apparatus further comprises a separation unit (6) in which the acid solution is treated by distilling to separate an acid distillate, and at least one circulation device for recirculating the acid distillate to the purification unit(3) .

14. The apparatus according to claim 12 or 13, c h a r a c t e r i z e d in that the apparatus further comprises a washing unit (14) for washing the purifiedcarbon product (4) to separate a metal leachate (16) from the purified carbon product.

15. The apparatus according to claim 14, c h a r a c t e r i z e d in that the apparatus comprises means for supplying the metal leachate (16) to the acid solution (5) .

16. The apparatus according to any one of claims 12 to 15, c h a r a c t e r i z e d in that the apparatus further comprises a precipitation unit (11) in which the acid solution (5) is treated by precipitating to separate metal salts, hydroxides and / or carbonates (12) .

17. The apparatus according to any one of claims 12 to 16, c h a r a c t e r i z e d in that the apparatus comprises at least one refinement device (17) for further treating the purified carbon product after the washing unit (14) .

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