A process for the preparation of a carbon product

Abstract

The invention relates generally to a process for the preparation of a carbon product having a high degree of graphitization in a high yield, comprising the steps of preparing a mixture comprising a carbohydrate or hydrocarbon containing starting material, a salt and a microwave or induction radiation absorbing material, preferably conductive carbon and wherein the salt comprises one or more salts selected from the group consisting of ZnCl2, MnCl2, FeCl3, AlCl3, MgCl2, CaCl3, SbCl2, and carbonising the carbon containing starting material to form the carbon product by heating with microwaves or induction radiation, preferably at temperatures between 200 and 1000°C in an atmosphere free of oxygen (O2), in an open reactor evaporating and removing water present or formed during carbonisation, converting the carbon containing starting material to the carbon product having a degree of graphitization of at least 45%, separating the carbon product from the one or more salts and preferably also post treating the carbon product to functionalise and / or further deoxygenate the carbon product. The invention also relates to the carbon product obtainable by the process and to use of the carbon product for the production of graphenes, carbon fibers and electronic applications.

Description

A PROCESS FOR THE PREPARATION OF A CARBON PRODUCTBACKGROUND OF THE INVENTION

[0001] The invention relates generally to a process for the preparation of a carbon product by carbonising a carbon containing starting material, preferably carbohydrate or hydrocarbon. The invention also relates to the carbon product obtainable by the process and to the use of the carbon product according to the invention for the manufacture of value-added carbon products such as graphene-oxides and graphenes.2. Description of the Related Art

[0002] In recent times the carbonisation of biomass has received a lot of interest because it does not produce a lot of CO2 or carbon containing volatiles compared to pyrolysis processes and in particular when compared to burning biomass. The carbon captured in the carbon product will not contribute to the global warming. The carbon efficiency of the process defines how much of the carbon in the carbon containing start material will be captured and not emitted to the atmosphere. Furthermore, the carbon product can have various different useful properties depending on the physico-chemical properties of the carbon product.

[0003] The carbon product can for example be used as soil improver or as absorbent in various processes. However, in recent times the interest has increased significantly in carbon for electronics purposes, such as conductive carbon in electrodes, in capacitors or in batteries.

[0004] Carbon materials produced from a biobased feedstock are sometimes also called biochar, even though the carbon material is not char. Biochar is the charcoal-like carbon product obtained when biomass, such as wood, manure or leaves, is heated in an oxygen deficient environment, i.e. pyrolysis. When biochar is chemically or physically activated, it is called activated or active carbon. Known physically activation processes include treatment with steam of carbon dioxide. Known chemical activation processes include treatment with phosphoric acid, zinc chloride, potassium or sodium hydroxide and potassium or sodium carbonate. Owing to the large surface area, high porosity and easy surface modification biochar and active carbon are widely applied as adsorbents.

[0005] Biochar is also well known for its agriculture amendment value for increasing crop yields, and as a form of activated carbon in water filtration and toxin remediation applications. It is also important as a carbon sequestration strategy as recognized by the UN Intergovernmental Panel on Climate Change (IPCC). The feedstock used, and quality produced of bio-chars can vary widely but it is possible through well-controlled pyrolysis technologies to create bio-chars that can be considered engineerable in their properties and serve as a new sustainable carbon platform. Such carbons would be suitable for more sophisticated applications like replacing the graphite and activated carbon electrode materials in high demand energy storage devices including Li-Ion batteries, and supercapacitors.

[0006] The summit of interest is to produce graphene, because it has high strength (200 times stronger than steel in perfect crystalline form) and super high electrical conductivity (5.8 times higher than copper compared on weight basis) and thermal conductivity. These properties promise application of graphene in many different applications such as anti-corrosion coatings and paints, efficient and precise sensors, faster and efficient electronics, energy storage (batteries), flexible displays, efficient solar panels, faster DNA sequencing, drug delivery, and more. Graphene has been described as potentially disruptive technology. However, graphene can be produced by methods that often are complex, expensive and have low production yields.

[0007] A process of particular interest starts from graphite (crystalline carbon) that occurs in nature Graphite comprises crystalline stacks of two-dimensional graphene (G) or graphene oxide (GO) layers. To obtain graphene as single layers the stack of layers in the graphite must be exfoliated. It is known to prepare graphene from graphite by the redox method wherein the interlayer distance in graphite is increased by first oxidizing the graphite to insert oxygen-containing groups in order to be able to exfoliate to single-layer structure (of GO) and then remove these oxygen groups by reductants to recover the original carbon plane with purely in-plane sp2 orbitals (reduced GO). These redox methods are known as Hummer’s method, Staudenmaier’s method or Brodie’s method.

[0008] Carbon can also be produced by carbonisation of carbon containing (bio-)material. It is desired that the carbonisation results in a carbon product having a high content of graphite, i.e. a high degree of graphitisation. The degree of graphitisation during carbonisation is characterised by the ratio of sp2 and sp3 characteristic peaks as can be determined by Raman in a method as described below: in graphene or graphene oxide layers the carbon atoms have a sp2 orbital hybridisation, as opposed to other carbon atoms having sp3 orbital hybridisation. Therefore, the ratio can be considered as a measure for the degree of graphitisation. A way of expressing the degree of graphitization (DOG) is lg / (ld+lg) wherein Ig and Id are respectively Raman adsorption intensities in band G at 1580 cm-1and Band D in the range of 1330-1340 cm-1which are representative of adsorption of sp2 carbon present in graphene layers and sp3 carbon present as defects in the graphene layers.

[0009] Ahmed A. MOOSA et. al. present (in Turk J Chem (2021) 45: 493-519) a review article on Graphene preparation and graphite exfoliation. Different graphene preparation methods include chemical vapor deposition on layers of transition metals, epitaxial growth on SiC, arc discharge, unzipping carbon nanotubes and oxidation of graphite to graphene-oxide (GO) with strong acids and strong oxidants to intercalate the graphite followed by exfoliation in water to single sheet GO and reduction of the GO to graphene. These methods are too intricate and complicated to be commercially relevant.

[0010] JP2022136860A describes an electric double layer capacitor (EDLC) as electricity storage device that comprises electrodes coated with activated carbon with a large surface area as collector, obtained by carbonisation of rice husk or coconut shell. Various different methods have beeninvestigated to optimize the carbon properties to achieve optimum properties, which include capacity, long cycle life, durability. Such capacitors using activated carbon attempts are described in WO2018 / 092721 , J P 2005-243933, JP 2014-165435, JP 2005-243933, JP 2007-67034 and JP 2016- 18808.

[0011] Sam et al in Synthesis of biomass-based carbon aerogels in energy and sustainability in Carbohydrate Research 491 (2020) describe carbon aerogel materials with very high surface area produced from biomass and their use i.a. as electrical conductor and supercapacitors. The fabrication procedure of carbon aerogels generally comprises four main steps i.e., sol-gel polymerization, aging, drying and carbonization. Biomass is converted to carbon aerogels in a process comprising a gelation or hydrothermal step of cellulose in water in an autoclave placed in an oven at a relatively high temperature, followed by a solvent exchange step, where the water in the hydrogel is replaced with an organic solvent such as acetone, and a (freeze-)drying step, where the organic solvent is extracted without collapsing the structure to form the cellulose aerogel, followed by carbonisation of the cellulose aerogel to a carbon aerogel by high-temperature pyrolysis (usually between 600 °C and 1000 °C) under an inert gas (typically nitrogen). The process is complex, costly and has low productivity, so impractical at large industrial scale required for example for batteries.

[0012] WO2017 / 205960 discloses a method for production of activated carbon with high surface area without using strong acids or environmentally unfriendly ZnCh The process comprises synergistic activation using a first and a second salt, by mixing a carbon precursor with the first salt, preferably an alkali salt, and a second salt, preferably a salt comprising P and O, N and O or S and O, and activating the mixture by raising the temperature to a temperature preferably between about 150 °C to about 1000 °C, for example preheating at 200-700°C and activating at 800-1000°C.

[0013] WO2018 / 141911 (corresponding to EP3577064) discloses a process for converting hydrocarbons, preferably a lower hydrocarbon such as methane, to produce hydrogen by contacting the hydrocarbons with a molten salt (ZnCh hydrate) at a temperature above 250°C, preferably above 500°C and wherein the hydrocarbons are cracked to produce hydrogen.

[0014] WO2016 / 087186 discloses a process for the conversion of cellulose biomass, comprising three steps: mixing a molten salt hydrate such as ZnCh hydrate with the biomass, at least partially hydrolysing the cellulose to monomer saccharides (such as glucose) and oligosaccharides, separating and converting the separated monomer- and oligosaccharides in a thermo-catalytic process, such as pyrolysis, catalytic pyrolysis, HTU or solvo-thermal conversion to make deoxygenated saccharides or pyrolysis oil.

[0015] WO2022 / 207757 discloses a process for converting waste material comprising a cellulose containing part and typically also a non-cellulosic material such as polymer material. The process involves contacting with a molten salt at low temperature below 125°C to dissolve cellulose in the molten salt and separating the solution from non-dissolved compounds. The cellulose is separatedfrom the solution. The non-dissolved non-cellulosic material and optional cellulose degradation products are carbonised. Carbonisation of cellulose itself is not described.

[0016] EP4206305 (corresponding to WO2023126410A1) describes a process to convert a carbon containing material, optionally containing a thermoplastic polymer material, in an anhydrous hydratable molten salt at temperatures between 200 °C to 500 °C and about ambient pressure in absence of oxygen and in presence of steam wherein the hydratable molten salt is rehydrated to phase separate the formed carbon phase and wherein the rehydrated molten salt is heated to form anhydrous molten and steam for use in the carbonisation step.

[0017] US2012 / 108827 describes a process comprising hydrolysing cellulose to sugars and hydrogenating and dehydrating sugars in ZnCL molten salt to produce fuel additives.

[0018] US2013 / 245252 describes a process comprising hydrolysing cellulose to glucose, hydrogenating to form sorbitol and after dehydrating to isosorbide in ZnCL molten salt

[0019] Zhu Hongli et al describe in a publication with the title "Low temperature carbonization of cellulose nanocrystals for high performance carbon anode of sodium-ion batteries" (NANO ENERGY, vol. 33, 1 March 2017, pages 37-44) a process wherein cellulose is first hydrolised in 60% sulfuric acid, and then the nanocellulose is isolated, cast to a film and subsequently heated at 240 °C for 8 h in air and carbonised at 1000°C (>2hrs) at which graphitisation occurred.

[0020] Matsagar Babasaheb et al describe in a publication with the title "Recent progress in the development of biomass-derived nitrogen-doped porous carbon" (Journal of Materials Chemistry A, vol. 9, no. 7, 1 January 2021 , pages 3703-3728) several preparation methods of nitrogen doped porous carbon (NPC) from biomass, such as Hydrothermal carbonization (HTC), pyrolysis, template directed synthesis process using a biomass containing such as aminoacids or N-containing carbohydrate, i.e. glucosamine. Biomass-derived NPCs were also obtained using chemical activation methods using chemical activation agents, such as KOH, NaOH, ZnCI2, K2CO3, KHCO3, H3PO4, and AICI3 at temperature typically in the range of 400 to 900 °C.

[0021] Liu Wu-Jun et al describe in a publication with the title "High-Yield Harvest of Nanofibers / Mesoporous Carbon Composite by Pyrolysis of Waste Biomass and Its Application for High Durability Electrochemical Energy Storage", Environmental Science & Technology, vol. 48, no. 23, 17 November 2014, pages 13951-13959) a process wherein sawdust was milled and preloaded with FeCI3 solution and dried. The obtained material was fast pyrolised at 873-1073 K (600 - 800C); volatiles were condensed in ethanol to produce bio-oil and solids M-NMCC were obtained (magnetic nanofiber / mesoporous carbon composites).

[0022] Xiaoxia Bai et al describe in a publication with the title "Hierarchical Porous Carbon with Interconnected Ordered Pores from Biowaste for High-Performance Supercapacitor Electrodes" ( NANOSCALE RESEARCH LETTERS, BIOMED CENTRAL LTD, LONDON, UK, vol. 15, no. 1 , 21 April 2020 (2020-04-21), pages 1-10) a process using biowastes as precursors for the preparation ofvalue-added nanomaterials; in particular using lignosulphonate as the precursor for preparation of capacitors. The process uses a silica template wherein lignosulphonate is loaded and carbonised at 900°C.

[0023] Sukamana et al described “Effect of ZnCI2 on properties of graphene produced from palm empty fruit bunch (Materials Science and Engineering 778 (2020) page 1 - 9) the production of graphene from waste from the production of palm oil by contacting empty fruit bunch with ZnCI2 and FeCI3, drying at 80 - 100°C and heating at 900°C.

[0024] Li Sun et al described in “ From coconut shell to porous graphene-like nanosheets for high- power supercapacitors (J. Mater. Chem. A, 2013, 1 ,6462) the synthesis of porous graphene-like nanosheets (PGNSs) with a large surface area via an easy and cost-effective SAG (simultaneous activation-graphitization) route from renewable biomass waste coconut shell using graphitic catalyst precursor (FeCI3) and activating agent (ZnCI2). The PGNSs possess good electrical conductivity due to the high graphitic degree. Coconut shell was mixed with 9 g of ZnCI2 in 50 mL of 3 M ferric trichloride (FeCI3) solution. Following an evaporation step at 80°C for 2 h under stirring and then drying at 100 °C in a conventional oven, the carbon precursor was obtained. Subsequently, the activation and graphitization process of the carbon precursor was carried out in a tubular furnace under a N2 atmosphere by heating the sample at a rate of 5 °C min-1up to 900 °C for 1 h.

[0025] EP3985072 (corresponding to US11859089) describes a process for producing crystalline carbon black by injecting a water-in-oil micro-emulsion comprising carbon components, metal catalyst nanoparticles and water into the reaction zone which is at a temperature of above 600 °C, preferably even above 1100 °C and quenching.

[0026] Libin Tang et al describe (in Journal of Materials Chemistry, 2012, 22, 5676-5683) the bottom-up synthesis of large-scale graphene oxide nanosheets wherein graphene oxide nanosheets (GONs) were grown using a hydrothermal method starting from glucose, sugar and fructose in a 50 mL Teflon-lined autoclave at growth temperatures ranging from 160 to 220 °C in growth period of 70 to 660 min followed by thermal annealing under nitrogen atmosphere at temperatures ranging from 450 to 1300 °C.

[0027] Daniele Perondi et al describe (in Microporous and Mesoporous Materials 323 (2021) 111217) the preparation of graphene-like porous carbon nanosheets GPCNs involving simultaneous pyrolysis and activation of carbon precursors in molten salt to generate GPCNs. In the FeCh / ZnCh system, the iron component facilitates the generation of GPCNs by forming a complanate carburized phase in the pyrolysis process, and ZnCh activates the formed carbon to produce a porous structure. Several types of metal-molten salts, such as LiCI / KCI, KCI / ZnCh, and FeCh / ZnCh systems have been developed to synthesize nanosheets. Cellulose, FeCh.H2O and ZnCh are mixed, evaporated for 2 hours at 80°C, dried at 100°C and subsequently pyrolised in a pyrolytic reactor at a temperature from 700 - 1000°C.

[0028] S. Saqib Shams et al describe (in Materials Letters 161 , (2015), 476-479) the synthesis of graphene from biomass using one-step pyrolysis wherein under flowing nitrogen atmosphere, camphor leaves were heated to 1200 °C at10°C / min and then cooled down to room temperature wherein the camphor leaves were reduced to few layer graphene.

[0029] Deepti Krishnan et al describe (in ACS nano VOL. 8, NO. 1 ,449-457, 2014) Graphene Oxide Assisted Hydrothermal Carbonization of Carbon Hydrates. The process comprises hydrothermal carbonization (HTC) of glucose or cellulose in an autoclave at temperatures of about 200°C under autogenic pressure in the presence of Graphene oxide (GO) to alter the morphology of its HTC product, resulting in more conductive carbon materials with higher degree of carbonization. The carbon yield is about 10 wt %. The product is subsequently annealed in a microwave to increase graphitization and conductivity.

[0030] Muhammad Taqi provides (in BioResources 15(4), 9756-9785) a review on Biobased graphene derived from biomass wastes. The methods involve thermal treatment of the biomass, such as pyrolysis, carbonisation and graphitisation and are all involve high and even very high temperatures.

[0031] Dohyung Kang et al describe (in Applied Catalysis B: Environmental Volume 254, 5 October 2019, Pages 659-666) Catalytic methane pyrolysis in molten MnCh-KCI wherein methane is decomposed to produce molecular hydrogen and solid carbon catalyzed by contact with molten KCkMnCh mixtures in a bubble column reactor from 700 to 1050 °C. The best carbon product obtained from the molten MnCl2(67)-KCI(33) comprises stacks of more than 30 layers of graphene having an l(D) / l(G) ratio of about 0.6 compared to carbon product obtained from KCI(100) having an I (D) / l (G) ratio of 1 .37 corresponding to amorphous carbon.

[0032] The prior art processes generally have one or more problems of being complex and expensive, having low production yields or producing low quality carbon material. Thus, there is a particular need for an improved process that is less expensive, has a good yield, preferably is scalable to high production volumes and produces good quality carbon material that can be used for example for the manufacture of electronic materials, for example for electrodes and capacitors, for producing Graphene, Graphene Oxide and Carbon Fibers.SUMMARY DESCRIPTION OF THE INVENTION

[0033] The present invention addresses these problems by providing a process for the preparation of a carbon product having a high degree of graphitization, comprising the steps of a. preparing a mixture comprising a carbon containing starting material, a salt and a microwave or induction radiation absorbing material, preferably a conductive carbon, i. wherein the carbon containing starting material is a carbohydrate or hydrocarbon containing starting material,ii. wherein the salt comprises one or more salts selected from the group consisting of ZnCh, MnCh, FeCh, AICH, MgCh.CaCh, SbCh, b. Carbonising the carbon containing starting material to form the carbon product i. by heating with microwaves or induction radiation, ii. preferably at temperatures between 200 and 1000°C, more preferably between 300 and 800°C, even more preferably between 400 and 600°C,Hi. in an atmosphere free of oxygen (O2), iv. in an open reactor evaporating and removing water present or formed during carbonisation, v. converting the carbon containing starting material to the carbon product having a degree of graphitization DOG of at least 45% wherein degree of graphitization is defined as lg / (ld+lg) wherein Ig and Id are respectively Raman adsorption intensities in band G at 1580 cm- 1and Band D in the range of 1330-1340 cm-1, c. Separating the carbon product from the one or more salts.

[0034] It was surprisingly found that the process of the invention produces a carbon product having a high degree of graphitization (DOG) and a low oxygen content and a high porosity with a very high carbon yield. The carbon yield CY of the obtained carbon product is defined as the dry weight of the carbon product relative to the theoretical amount of carbon in the carbon containing starting material, which can be calculated from the molecule formula or measured. The carbon yield CY in the process of the invention is very high and carbon yields of over 70, or 80 or even over 90% have been achieved, which also implies that the process produces very low amounts of carbondioxide and very low amounts of below liquid hydrocarbons. The energy consumption of the process is relatively low due to the energy efficiency of microwave heating in the presence of a microwave or induction radiation absorbing material such as conductive carbon. The process thus is very environmentally friendly. Conductive carbon is the preferred microwave or induction radiation absorbing material because the end-product of the process of the invention is a conductive carbon that can be used in step a) of the process.

[0035] A further advantage of the process is that the carbon product can relatively easily be recovered by washing out the salt, which is easy compared to prior art carbonisation or pyrolysis processes as the carbonisation product of the invention has a low liquid hydrocarbons residue and there is no need to for additional separation or cleaning steps for side product.

[0036] In the carbonisation process a bio-based material can advantageously be used that has a high oxygen content, which is normally a disadvantage as the oxygen needs to be removed for most purposes (like bio-oil), but for the present envisaged use as precursor for carbon, functionalized carbon and graphene materials it is actually not a problem but an advantage.

[0037] An advantage of the process of the invention is that it has the flexibility to produce a range of carbon products with properties that can vary between wide ranges and can easily be tailored to meet the requirements in a wide range of different applications as will be described below.

[0038] The inventors have found that the carbon product obtained by the process of the invention having a very high degree of graphitization of at least 45% is a very suitable starting material for production of graphene because the carbon product has very little defects in the graphene oxide sheets.

[0039] The carbon product of the invention contains oxygen groups (GO sheets) originating from the used carbon containing starting material and does not need to be oxidised to be exfoliated as in the above-described redox method of Hummer, Staudenmaier or Brodie. This is an advantage because the prior art oxidation method introduces defects in the graphite sheets, which will deteriorate properties in the eventually obtained reduced graphene-oxide. The advantage of the carbon product of the invention is that the oxidation step is not necessary, and fewer defects are created in the layer structure, which has the potential to create a reduced graphene-oxide with properties that are closer to pure graphene.

[0040] The optionally exfoliated carbon product can be further subjected to a posttreatment to reduce the oxygen content and convert the graphene-oxide GO to graphene (G) and to increase conductivity and capacitance. This is also called the deoxygenation step. The thus obtained carbon product of the invention can have conductivity (CO), capacitance (CA) and porosity on par with commercial products that are more difficult and expensive to produce; for example Standard EDLC- Capacitors Kuraray YP-50F (has CO = 20 S / m and CA=32.5 F / g and Iodine number I = 1600, and Methylene Blue number MB = 600).

[0041] Typically, the carbon product has an oxygen content OC (i.e. bound oxygen atoms for example in hydroxyl, ether or carboxylic groups) between 1 and 20 wt%. A high oxygen content in the carbon product provides for hydrophilic and reactive properties. Such carbon material was found to be a good precursor material for several applications. It can easily be dispersed in water, can absorb and form film on polar surface, can bind ions, such as metal ions, and thus can be modified and functionalized relatively easily. A relatively high oxygen content is also desired for adhesion on polar surfaces, for example for use in metal electrodes or capacitors.

[0042] On the other hand, in some applications where high conductivity is desired the oxygen content OC is preferably low; typically, below 20 wt%, below 10 wt% or even below 5 wt%. Such relatively low OC, high DOG and high conductivity is achieved in particular when the carbonisation is done in anhydrous molten salt and in particular when using microwave heating in combination with a conductive carbon mixed into the carbon containing start material.

[0043] The invention therefore also relates to a carbon product obtainable by the process according to the invention; in particular to a carbon product having a DOG of at least 45%, preferably at least 50%, more preferably at least 55%

[0044] Accordingly, the invention also relates to the use of carbon products according to the invention as a precursor for the manufacture of Graphene Oxide Graphene or Carbon Fibers.

[0045] Accordingly, the invention also relates to the use of carbon products according to the invention for the manufacture of electrode materials or electrodes, wherein optionally residual molten salt used in the carbonisation step is used as electrolyte.DETAILED DESCRIPTION OF THE INVENTION

[0046] In the process of the invention the salt preferably is a metal halide salt in hydrated or anhydrous form, wherein the metal preferably is Zinc, Aluminum, Antimony, Manganese, Calcium, Iron or Magnesium or combinations thereof and the halide is chloride or bromide or combinations thereof, preferably ZnCh, MnCh, FeCh, AlCh, MgCh.CaCh, SbCh, These molten salts are hydratable and have appropriate low melting temperature, in particular in hydrated state. The molten salts, in particular ZnCh, have catalytic properties for the carbonisation process. It was found that the molten salts, in particular ZnCh, create high surface areas in the carbon product, which is beneficial for adsorption properties and as collector for electrode materials. An advantage of using a molten salt as the solvent in the process of the invention is that it is easy to recycle the salt after separation of the carbon product back to the step a).

[0047] The term molten salt is used to indicate that the salt is used at an elevated temperature where it changes to the liquid state and can act as a ionic solvent, which implies that the temperature is above the melting temperature in case of a pure salt or above a eutectic melting point in case of a mixture of salts or, in case of a hydrated salt, the temperature where the salt dissolves in its hydrated water. In all cases reference is made to a molten salt.

[0048] The most preferred salt is ZnCh. Preferably the one or more salts comprise at least 50 wt.%, more preferably at least 70 wt% even more preferably at least 80 wt% and most preferably at least 90 wt% ZnCh relative to the total amount of salts, with the remainder of the molten salt being one or more other metal halide salts, preferably AlCh, MnCh, SbCh, MgCh, CaCh or FeCh and more preferably FeCh Most easy and preferred is that only ZnCh is used as the salt. Extra acid (preferably HCI, in case of Zinc-chloride) may be added to promote carbonisation.

[0049] Preferably the carbon containing starting material comprises a hydrocarbon selected from the group of paraffins, ethylene- or propylene containing polymers and lignin or, more preferably, the carbon containing starting material comprises a carbohydrate selected from the group of monosaccharides, oligosaccharides, polysaccharides and most preferably cellulose or glucose ormixtures thereof and preferably in an amount of at least 50, 70, 80 or even at least 90 wt% relative to the total weight of the carbon containing starting material.

[0050] The carbon containing starting material can in principle be any biomass source, for example from a waste stream. Preferably, the carbon containing starting material is carbohydrate containing starting material preferably wood, saw-dust, paper, cotton or empty fruit bunch, which is preferably finely comminuted to increase contact with the salt. A preferred bio-source can be wood comprising cellulose and lignin.

[0051] Most preferred are carbohydrates as starting material because in molten hydrated salt, in particular in ZnCh, carbohydrates carbonize easily by splitting off water and surprisingly form a carbon product with a well-developed graphite structure as exemplified by the high degree of graphitization (DOG), with good porosity and leaving some oxygen in the formed carbon product. Suitable carbohydrates can be selected from the group of monosaccharides, oligosaccharides, polysaccharides or mixtures thereof. Most preferred are cellulose and glucose.

[0052] In step a) a mixture is prepared comprising a carbon containing starting material, a salt and a microwave or induction radiation absorbing material, preferably a conductive carbon. This can be done in several ways. In a first general embodiment a microwave or induction radiation absorbing material, preferably a conductive carbon, is added and mixed with the carbon containing starting material and the salt. In a second general embodiment a microwave or induction radiation absorbing material is formed in-situ in a partial carbonisation pre-treatment in the presence of water (wet pretreat) and the resulting dried partially carbonized mixture is fed to carbonisation step b).

[0053] In particular, the mixture of the carbon containing starting material, the salt and the microwave or induction radiation absorbing material, preferably a conductive carbon, is prepared by a) adding a microwave or induction radiation absorbing material, preferably a conductive carbon, to a mixture of the carbon containing starting material and the salt, or by b) mixing the carbon product obtained by step b) or c) of the process of the invention with the carbon containing starting material and the salt, or by c) partially carbonising the carbon containing starting material, preferably a carbohydrate containing starting material, forming the microwave or induction radiation absorbing material, in-situ by i. preparing a slurry of a mixture comprising the carbon containing starting material and the salt in water and heating the slurry at a temperature between 50 and 150°C to partially carbonise the carbon containing starting material, ii. wherein the amount of water in the slurry is preferably at least 50 wt% relative to the total weight of the slurry,iii. drying the slurry, preferably at a temperature between 50 and 150°C, before carbonisation step b); or by d) carbonising a carbohydrate containing starting material forming radiation absorbing material, in situ by a first wet carbonisation step comprising i. Contacting the carbohydrate containing starting material with a hydrated salt wherein the hydrated salt comprises one or more hydrated salts selected from the group consisting of ZnCh, MnCh, FeCH, AlCh, MgCh, CaCh, SbCh hydrates, wherein preferably the water content is more than 1 wt% and preferably below 30wt%, ii. Carbonising the carbohydrate containing starting material in mixture with the hydrated molten salt by heating at temperatures between 100 and 300°C, preferably between 125 and 275°C, more preferably between 150 and 250°C in a closed reactor system, preferably in an oven or with microwaves, in an atmosphere free of oxygen (O2), wherein either1 . the carbonisation is partial and the obtained mixture of salt and carbohydrates, that are partially carbonized to in situ form radiation absorbing material, is dried and subjected to carbonisation step b) of the process of the invention OR2. the carbonisation is done to form a carbon product having a degree of graphitization DOG of at least 45%, preferably at least 55% and an oxygen content between 20 and 40 wt%, followed by separating and drying the obtained carbon product and optionally subjecting to a deoxygenation step to reduce oxygen content to form a highly conductive carbon product and then adding that highly conductive carbon product to the carbon containing starting material and salt in step a) of the process of the invention.

[0054] It has been observed that mixtures obtained in the wet pretreat preparation steps c) and d) described above did not need addition of radiation absorbing material to be heated by microwave radiation in carbonisation step b) even after drying. It is believed that in these preparation steps partial carbonisation takes place wherein conductive carbon is formed in-situ; this is supported by the brownish colour of the partially carbonised mixture.

[0055] The carbon containing starting material can be dry mixed with the salt or can be wet mixed with the salt and water followed by drying, which can help to increase the contact with the salt. This can be done at room temperature. Alternatively, the carbon containing starting material can directly be contacted with molten salt at elevated temperature. The mixture is preferably substantially dry when subjected to the carbonisation temperature in step b). Some small amount of water can be tolerated as it will evaporate in the open reactor system when heating to the carbonisation temperature in step b). A too high initial amount of water results in foaming and poor control of the process. The mixturecomprising the carbon containing starting material, the salt and the radiation absorbing material preferably comprises less than 5 wt% water relative to the total weight of the mixture, preferably less than 2 wt% and more preferably less than 1 wt% water and in case the water content in the mixture is higher than 5 wt%, the mixture is dried before the carbonisation step, preferably at a temperature below 120°C.

[0056] The amount of carbon containing starting material preferably is between 5 and 80 wt.%, preferably between 10 and 70 wt, more preferably between 30 and 60 wt% relative to the total weight of carbon containing starting material and the salt and wherein the conductive carbon is preferably present in an amount between 5 and 30 wt%, preferably between 7 and 28 wt% more preferably between 10 and 25 wt% relative to the weight of the carbon containing starting material.

[0057] The ratio of the salt and the carbon containing starting material preferably is between 0.5 and 50, preferably between 0.5 and 30, more preferably between 1 and 10. The ratio of the radiation absorbing material, preferably conductive carbon, to the carbon containing starting material is between 0.01 and 1 , preferably between 0.05 and 0.5, more preferably between 0.07 and 0.2 and most preferably the ratios of the carbon containing starting material to the salt to the radiation absorbing material, preferably conductive carbon are around 1 :1 :0.1 .

[0058] Optionally (and preferably) a carbon seed material is added to the carbon containing start material to seed and accelerate the carbonisation process. A suitable seed material is graphene-oxide or carbon black. Graphene-oxide works well but is too expensive, so carbon black is preferred. In the process of the invention, the conductive carbon and the seed material can be different materials but preferably are one and the same material: conductive carbon such as carbon black. As described above, the carbon seed material as well as the conductive carbon is the carbon product obtained by the process of the invention having high degree of graphitization or DOG>45% or preferably above 50% that is in-part recycled to the process step a). In case carbon product obtained by process of the invention is used as seed and as conductive carbon, the upper limit is not critical because it is the same as the envisaged end carbon product but is preferably low in view of process efficiency.

[0059] In step b), the carbon containing starting material is carbonised to form the carbon product in mixture with the molten salt by heating with microwaves or induction radiation in the presence of radiation absorbing material, preferably conductive carbon as adsorbent for the electromagnetic waves of the microwave or for the magnetic fields in induction heating. Microwave heating and induction heating are fundamentally different in how they generate and transfer heat, but both microwave heating and induction heating can generate heat in the presence of a conductive carbon in the mixture. Hereafter, descriptions of microwave heating similarly apply to induction heating.

[0060] The microwave heating provides extremely fast en efficient internal heating of the carbon containing material. The temperatures quickly rise to temperatures between 200 and 1000°C, preferably between 300 and 800°C, more preferably between 400 and 600°C. It can easily beestablished that the temperature is above 600°C because then the carbonising product glows. The temperature can be measured contactless with an infrared thermometer or with a thermocouple that is shielded against the microwaves effect on the metal. The heating can be done in two or more stages at increasing temperature levels with increasing microwave power. The carbonisation is done in an open reactor evaporating and removing water present or formed during carbonisation. Surprisingly it was found that carbonisation to a high degree of graphitization, typically with DOG above 45% or 50%, took place in a very short time; typically already between 5 and 15 minutes, and with a very high carbon retention; typically over 80 or even over 90%. That means that most carbon is graphitized and very little carbon byproduct is formed, such as CO2 and liquid hydrocarbons, which is also indicative of low defects in the structure of the obtained product. The carbonisation is done in an atmosphere free of oxygen (oxygen here means molecular oxygen or Chto avoid combustion of the carbon. The mixture in carbonisation step b) is preferably heated with microwaves at a power between 120 and 1000 W, preferably between 200 and 500W, preferably for a time between 5 and 30 minutes. In general, the microwave radiation power needed to heat the sample is dependent on the equipment, the sample size and the amount of radiation adsorbing material. If the power is too low for the specific sample, the time required to achieve the desired degree conversion will be longer. The required microwave power and time for a given sample and equipment can be established by a making a calibration curve of the power and time against the obtained DOG and / or oxygen content.

[0061] The amount of microwave absorbing material is chosen to have an effective transfer of heat in the carbon product. The microwave absorbing material is preferably mixed and as homogeneously dispersed as possible. Good results are obtained when the weight ratio of microwave absorbing material and hydrated salt solvent is between 0.05 and 0.5, preferably between 0.18 and 0.3 and more preferably between 0.15 and 0.25. In this embodiment the heating is very efficient, and carbonisation time can be less than 1 hours, preferably even less than 0.5 hours. Very low oxygen contents and very high conductivity can be obtained when using longer microwave times and higher microwave energy. A microwave energy between 50 and 500 W can suitably be used to mildly heat the mixture for carbonisation in a time frame between 5 and 30 minutes. A microwave energy between 500 and 1000W can suitably be used to heat the mixture for further carbonisation to very low oxygen content. The degree and speed of carbonisation also depend on temperature and time and are chosen in combination to convert the carbon containing starting material to the carbon product to a degree of graphitization DOG of at least 45%, preferably at least 55%, more preferably at least 60% and even more preferably at least 65%.

[0062] After the carbonisation step b) the formed carbon product is separated from the molten salt in step c). The separation is preferably done by addition of water to precipitate carbon product that is still dissolved in the molten salt and to extract the salt from the carbon product by dissolving it in the water. Water is also preferred to separate the salt from the carbon product because it can more easily be removed to recover and recycle the molten salt to step a). Cold water is preferred in the first addition of water as it also quickly cools the molten salt.

[0063] Preferably, the salt is further separated from the carbon product by washing with water, preferably at a temperature between 50 and 90 °C. Washing is preferably done in multiple steps depending on the required purity of the carbon material. Preferably, one or more solid separation steps are performed either by centrifugation and / or by filtration after each washing step. Typically, a washing cycle comprises washing the carbon product by stirring in water at a temperature between 50 and 90 °C for a time preferably between 1 and 60 minutes, filtering, and washing the separated carbon product on the filter; this washing cycle is preferably repeated one or more times until the Zinc concentration is below 0.5wt%, preferably below 0.2 wt% and more preferably below 0.1 wt%. Another suitable method is washing by refluxing in water in a Soxhlet type of extraction.

[0064] More preferably, the carbon product is separated from the one or more salts by washing with acidified water, preferably having a pH below 4, preferably below 3, more preferably below 2 and most preferably below 1 . It was found advantageous to wash with acidic washing water to improve the efficiency of the washing step and to prevent precipitation of metal salts, for example ZnOHCI, after dilution with water. Any liquid carbons that may be formed will mainly be carboxylic acids that remain in the salt and wash water. It was observed that the washing water was clear which is indicative that the carbonisation is proceeding without producing organic products and char as occurs in pyrolysis process. Reversely, when brownish discoloration of the wash water is observed it is indicative that the carbonisation did not go well and that the product yield and carbon yield is low.

[0065] The separation and washing can optionally be done by addition of an organic anti-solvent that causes the carbon- product to separate from the molten salt followed by separating the precipitated or coagulated carbon product for example by filtration. Suitable organic anti-solvents are C1 to C8 alcohols and ketones, in particular the alcohols of the group of straight chain and branched chain C1 to C4 alcohols, such as methanol, ethanol, propanol, and iso-propanol. Particularly suitable ketones include the C3 to C5 ketones such as acetone and methylethylketone (MEK). Preferred organic coagulation agents are acetone, ethanol and t-butyl alcohol. Such organic anti-solvents can be used after cooling, preferably after the first addition of water to more completely separate carbon product from the salt and enhance extraction of liquid hydrocarbons from the carbon product. Optionally, the organic anti-solvent is used in a mixture with water for washing the carbon product and / or is used alternating with water washing steps.

[0066] After separation and optional washing the carbon product is dried by heating, preferably at a temperature between 80 and 150 °C, more preferably between 80 and 120°C, to obtain the carbon product. This product is preferably milled to a fine powder.

[0067] In a special embodiment the washing is stopped before completely removing the salt to intentionally leave a residual amount of the salt in the formed carbon product, wherein the amount of residual salt is between 0.01 - 20 wt%, preferably 0.02 - 15 wt%, more preferably 0.5 - 10 wt% of the total weight, optionally comprising a further step wherein the residual metal-halide salt is converted to it’s metal-oxide and / or metal hydroxide, preferably by addition of a strong base, which preferably isKOH or NaOH, preferably ZnCh converted to ZnO and / or Zn(OH)2. Optionally, the salt is exchanged with another salt, preferably before drying to modify the properties of the carbon product.

[0068] The carbon yield CY of the obtained carbon product (dried), defined as the dry weight of the separated carbon product relative to the theoretical amount of carbon in the carbon containing starting material, is preferably at least 40 wt%, preferably at least 45 wt% and more preferably at least 50 wt%, but a CY of at least 60, 70 or even 80 wt% is achievable. The relative graphitization yield, defined as the wt.% percentage of carbon in the starting carbon material that is converted to graphitized carbon product (DOG x CY) is at least 20%, preferably at least 25%, more preferably at least 30 % and most preferably at least 4%. The MB number and I number can vary in wide ranges typically the I number is 200-2000 and the MB-number is 100-700.Post-treatment step d)

[0069] The high DOG and oxygen content OC makes the product suitable for production of conductive carbon, in particular graphenes, which have very interesting uses. The OC of the obtained carbon product can also be used to functionalize the carbon product. Thus, in a preferred embodiment, the carbon product obtained in the process step b) or c) is preferably post-treated in one or more further steps d) that may comprise 1) a step to reduce the oxygen content (deoxygenation post-treatment), preferably by heating, optionally with reducing agent wherein the oxygen content can be reduced for example for enhancing electrical conductivity and / or 2) a functionalization step wherein the carbon product is modified to contain one or more heteroatoms, preferably sulfur, nitrogen or metals. These embodiments will be described in more detail below.Deoxygenation post-treatment step d)

[0070] The inventors have found that the carbon product obtained by the process of the invention having a DOG of at least 45%, preferably at least 55 % and an oxygen content in the range between 1 and 20 wt% is a very suitable starting material for making graphene type of product. Thus, it is preferred that the carbon product obtained in process steps b) or c) of the invention is subjected to a post-treatment step d) to reduce the oxygen content of the carbon product, optionally after having been exfoliated.

[0071] In known prior art processes, graphene is prepared by the redox method wherein the interlayer distance in graphite is increased by first oxidizing the graphite to insert oxygen-containing groups in order to be able to exfoliate to obtain single-layer structure (of GO) and then remove these oxygen groups by reductants to recover the original carbon plane with purely in-plane sp2 orbitals (reduced GO). This is known as Hummers method, Staudenmaier’s method or Brodie’s method. The oxidation method introduces defects in the graphite sheet, which will also deteriorate properties.

[0072] The advantage of the carbon product of the invention is that it already has a relatively high degree of graphitization and relatively high oxygen content when it originates from carbohydrates that comprises a lot of oxygen, so with this carbon product no oxidation step is necessary for exfoliationand less defects are created in the layer structure, which has the potential to create a reduced graphene-oxide with properties that are closer to pure graphene.

[0073] Exfoliation can be done in several known ways. A preferred way is Liquid phase exfoliation wherein the carbon product is dispersed in a suitable chemical environment (e.g., in an organic solvent or in a mixture of water and surfactant). A surfactant or dispersing agent is used to match the surface tension of the solvent to the carbon product. Suitable surfactants are N-methyl-2-pyrrolidone (NMP), ortho-dichlorobenzene and dimethylformamide. The exfoliation is generally driven by mechanical force provided by, e.g., ultrasound or a blender. Examples of methods for liquid phase exfoliation can be found in Nature Materials 13 p. 624-630 (2014) and Nature Nanotechnology 3, p. 563 - 568 (2008). Exfoliation can also be done by electrochemical cathodic treatment. Examples of methods for electrochemical expansion can be found in WO2012120264 A1 .

[0074] The inventors further found that increasing the conductivity by the post-heating deoxygenation step can reduce the porosity and capacitance. However, it was found that the porosity and capacitance are reduced to a lesser extend if the carbon product to be subjected to the postheating step has a relatively low oxygen content and preferably when the deoxygenation treatment is relatively mild. This is exemplified in the examples in Table 1 . Therefore, the invention also relates to a process wherein the carbon product obtained by the step b) or c) has a DOG of at least 45%, preferably at least 55%, more preferably at least 60% and even more preferably at least 65% and an oxygen content between 1 and 20 wt%, preferably between 2 and 15 wt%, more preferably between 2 and 10 wt% and even more preferably between 2 and 5 wt% and, for the purpose to increase the conductivity, the process comprises a deoxygenation post-treatment step d) wherein the oxygen content of the carbon product is reduced to below 5 wt%, preferably below 3 wt% and more preferably below 2 wt% wherein preferably the deoxygenation post-treatment step d) is a post-heating step. The obtained carbon product has a high conductivity (CO>20 S / m) combined with good capacitance (CA>15, preferably >20 F / g) and good porosity as reflected by the relatively high I and MB number.

[0075] Suitable known deoxygenation post-treatment processes are chemical reduction, thermal reduction, hydrothermal / solvothermal reduction, electrochemical reduction or photocatalytic reduction. Preferably a post-heating treatment (thermal reduction) is used to deoxygenate the carbon product obtained in step b) or c). Another suitable deoxygenation post-treatment is Chemical reduction because it is relatively easy to set a mild deoxygenation condition by choice of an appropriate concentration and reducing power. In this process reducing agents are added to a suspension of the (preferably exfoliated) carbon product. Suitable reductants are hydrazine / hydrazine hydrate, ammonia, sodium borohydride (NaBH4), hydroiodic acid (HI), sodium dithionite, metal salts (e.g., SnCL), organic reducing agents such as gallic acid, Ethylenediamine, Sodium citrate, L-cysteine and L-ascorbic acid (vitamin C).Deoxygenation by Post-heating

[0076] The separated and optionally washed and dried carbon product is preferably heated in a further heating step d) to a temperature above 200°C, preferably above 250°C, more preferably above 300°C preferably in oxygen free atmosphere, in an oven or preferably by microwave heating. This process will result in a high yield of graphene-like carbon having high porosity, a high capacitance and a high conductivity that can meet industry standards of conductive carbon.

[0077] In view of achieving high conductivity, it is preferred that the thermal reduction (deoxygenation) is done by post-heating the carbon product at a temperature between 300°C and 1500°C, preferably 400°C to 1000°C, more preferably 500°C to 900°C in oxygen free atmosphere, preferably in an open reactor, by heating in an oven or by heating with microwave or induction radiation. The upper limit in heating temperature is preferably high in view of speed of conversion but is chosen sufficiently low to not cause too many defects in the graphene structure. The reduction of oxygen content can also be achieved by increasing the time of exposure to the heating.

[0078] It is preferred that the carbon product is subjected to a post-heating step d) by microwave radiation, preferably at a power between 100 and 1000 Watt per 10 - 100 gr sample and preferably for a time between 1 and 60 minutes, more preferably between 1 and 40 minutes and even more preferably between 1 and 20 minutes. In a preferred embodiment multistep post-heating is used in two or more step wherein the temperature and / or the power of the microwave radiation is increased; for example the temperature in a first heating step is below 800°C, preferably below 700°C or even below 600°C and the temperature in the subsequent heating step is higher than the temperature in the first heating step but below 1000°C, preferably below 900°C or below 800°C. Alternatively, the microwave radiation power in a first heating step is between 120 and 400W per 10 - 100 gr sample and the power in the subsequent heating step is higher than in the first step and preferably between 300 and 800 W per 10 - 100 gr sample.

[0079] A particular embodiment of the process if the invention is the carbonisation of wood, for example in the form of saw dust. Wood comprises lignin and cellulose that can both be carbonised with high CY, to a high DOG and converted to a carbon product with high porosity, CA and CO. The process for the carbonisation of wood preferably comprises forming a mixture of the carbon containing material, the salt, preferably ZnCh optionally in combination with FeCh, and optionally also a microwave absorbing material, preferably recycled carbon product obtained by the process of the invention, and subjecting the mixture to a wet pretreat, preferably the wet pretreat option c) as described above, followed by drying, carbonising the obtained dried mixture to one or more postheating steps with microwave radiation, washing the product to remove the salt and subjecting the obtained separated dried carbon product to one or more post-heating steps with microwave radiation to deoxygenate to a CO above 10, preferably 15 S / m whilst maintaining an I number >1200 and an MB number >350.

[0080] The post-heating may reduce the carbon yield CY and the DOG, but the CY and the DOG of the post-heated carbon product are still surprisingly high. Preferably, the CY is still at least 50 wt%,preferably at least 60 wt% more preferably least 70, and even more preferably at least 80 wt% and the DOG is still above 40%. The post-treated carbon product obtained in step d) also has a very good porosity characterised by an MB number of at least 200, preferably at least 300, more preferably at least 400 and most preferably at least 600 and an I number of at least 500, preferably at least 800, more preferably at least 1000 even more preferably at least 1200 and most preferably at least 1600. Porosity is important for use in capacitors.

[0081] The invention also relates to a carbon product obtainable by the process according to anyone of the embodiments of the process of the invention described above. In particular, the invention relates to the carbon product obtainable by the process having before post-treatment step d), a DOG of at least 45%, preferably at least 55 % and an oxygen atom content between 1 and 20 wt%, preferably between 1 and 10 wt%, more preferably between 1 and 5 wt%, optionally comprising a residual fraction of the metal halide salt and / or it’s metal-oxide or metal hydroxide as electrolyte, preferably ZnCh and / or ZnO or Zn(OH)2.

[0082] The invention also relates to the use of the carbon product according to any of the embodiments of invention as a precursor for the manufacture of Graphene-oxide, Graphene, or Carbon Fibers.

[0083] The invention also relates to the carbon product obtainable by the process of the invention after post-treatment step d), comprising a. an oxygen atom content between 0 and 5 wt%, preferably between 0 and 3 wt%, more preferably between 0 and 1 wt%, b. a conductivity of at least 20, preferably at least 50, 75 or even at least 100 S / m, c. a capacitance of at least 15, preferably at least 20, more preferably at least 25 F / g d. an MB number of at least 200, preferably at least 300, more preferably at least 400 and most preferably at least 600 and e. an I number of at least 500, preferably at least 800, more preferably at least 1000 even more preferably at least 1200 and most preferably at least 1600.

[0084] The invention also relates to the use of the above carbon product for the manufacture of electrode materials or electrodes, capacitors and conductors.

[0085] The carbon product of the invention, especially the carbon product with somewhat higher OC (higher than about 5 or 10 wt%), can be functionalized relatively easily in view of different uses of the carbon product; for example to improve the amount or specificity of absorption of target molecules. This can be done in further steps comprising; a functionalization step wherein the carbon product is modified to contain one or more heteroatoms, preferably sulfur, nitrogen or metals,wherein preferably a functional compound comprising such heteroatoms is added after the carbonisation step to absorb in the carbon product and bind or react with oxygen in the carbon product, for example by impregnation of a solution of such functional compound and optionally drying optionally followed by a treatment, preferably a heat treatment at temperature above 350°C, to bind the functional compound in the carbon, and / or optionally to reduce the oxygen content, preferably by heating, optionally with reducing agent wherein the surface area and / or oxygen content can be reduced for example for enhancing electrical conductivity.

[0086] Alternatively, the functionalization step can be done by adding a functional compound before the carbonisation step b); these functional compounds are preferably sulfur and / or nitrogen containing organic compounds that also carbonize during the carbonisation step. Metal containing functional compounds are preferably added to the carbon product after carbonisation.

[0087] The invention also relates to functionalized carbon product obtainable by the process described above.

[0088] The carbon product obtained by the process is a powder having granular carbon particles. The carbon product can be shaped in ways known in the art (granulating, extruding, compacting etc). In a special embodiment the shaping is done before carbonisation by shaping the mixture of the carbon containing start material and molten salt into a shape and then carbonising. For example, a mixture of cellulose and molten salt can be spun to a fiber and subsequently carbonized according to the process of the invention followed by (optionally partly) removing the salt.

[0089] Alternatively, and more easily, the shaping is done after carbonisation. Carbon fibers can be made by spinning the mixture of the carbonized carbon product in the molten salt after carbonisation step b), optionally after mixing with a binder, into a water bath wherein the molten salt is removed to obtain a fiber comprising the carbon product of the invention, which then can be subjected to further treatments as described above, for example functionalization and heating.

[0090] Alternatively, and more easily, the shaping is done after carbonisation and separating step c) and optionally after washing step d). For example, the carbon product obtained after step c) or d) (optionally dried and further heated or functionalized) comprises a low amount of water forming a paste like mixture that can readily be shaped and subsequently dried or heated at high temperature for example as defined in step e) to increase the hardness of the shaped carbon product and increase conductivity. Optionally the carbon product is mixed with a binder material before shaping.

[0091] The invention also relates to the use of the carbon material obtainable by the abovedescribed processes for the manufacture of electrode materials or electrodes, wherein optionally residual salt is used as electrolyte.

[0092] Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art.

[0093] Further modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention. The invention is further illustrated by the following examples.

[0094] The invention is illustrated by the experiments described below.DESCRIPTION OF EXPERIMENTSDegree of graphitisation by Raman spectroscopy

[0095] Analyses were performed in a Horiba-Jobin Yvon iHR320 system with a Symphony detector coupled with an Olympus microscope. The laser used was HeNe (632.8 nm), with approximately 10 mW of power. Raman spectroscopy analysis was conducted to evaluate the degree of graphitization of materials produced. From Raman spectra the ratio of ID / IG bands were determined. Band D is usually found in the range of 1330-1340 cm- 1 and is linked to sp3 carbon that is not present in graphene layers whereas band G in 1580 cm- 1 is linked to sp2 carbon that is present in graphene layers. A lower ID / IG ratio implies a carbon product having high graphitization, having higher amount of graphene (or graphene oxide) and a more orderly graphite structure.Measurement of oxygen content and C and H content

[0096] The oxygen content is defined as the weight percentage of oxygen atoms in the obtained carbon product divided by the weight of the carbon product, wherein the weight of the oxygen atoms is calculated from the mole percentage Oxygen atoms.

[0097] The Oxygen analysis was carried out on a Fisons instrument (now Thermo) elemental analyser model EA1108 configured for Oxygen analysis. The technique used is the Unterzaucher pyrolysis method. The analysis was perfomed externally by Measurelabs, Helsinki, Finland

[0098] A Flash 2000 (Interscience) instrument was employed to analyze the elemental composition (C, H, and O mass fraction) of solid carbon samples. In this analysis, the samples were completely oxidized in O2 and the [C], [H] mass fraction were calculated directly based on the amount of CO2 and H2O formed, and the [O] mass fraction was obtained by difference.Measurement of methylene blue numberWeigh 0, 2, 4, 6, 8, 10 g of a methylene blue solution^ mg / g) in a 15 ml vial and fill it up with D- water to a total weight of 10g, and homogenize it.Measure the transmission on a photometer(520nm) in a cuvette and plot the transmission against the methylene blue concentration as a standard curve.10 mg(d.b.) of carbon material is weighed into a 10 ml glass tube.10 g of methylene blue solution and a mini magnetic stirrer are added. Sample is stirred for 24 hrs.200 mg of sample solution is weighed in a cuvette through a Syringe filter (0.45micron). Demi water is added until the content of cuvette is 4.0 gram.Homogenize content of cuvette.% Transmission is measured on Photometer (520nm) against demi water as blank(100%T). Amount of MB remaining (g / g) is read on the X-axis of the standard curve.

[0099] The methylene blue (MB) number is calculated as MB number (mg / g) = m(1000- C) / (A*B / 100) wherein A = g Carbon sample B = wt% solids Carbon sample (120°C / 2 hrs) and C = Amount of MB remaining in solution read from the standard curve(mg)Measurement of Iodine number

[0100] The Iodine number is measured according to ASTM D 4607.

[0101] The methylene blue number and the iodine number determination are simple measurements that can be used for estimation of surface area and pore volume of activated carbons. The methylene blue molecule is relatively big and is mainly adsorbed in mesopores. However, a small portion is also found in larger micropores. The smaller iodine molecule makes penetration in micropores possible. A high methylene blue number implies a high volume and surface area in mesopores. A high iodine number implies a high volume and surface area in micropores. The surface area, the micropore volume and the total pore volume of activated carbons can be estimated by iodine and methylene blue numbers using multiple regression as demonstrated by Cleiton A. Nunes e Mario C. Guerreiro in Quim. Nova, Vol. 34, No. 3, 472-476, 2011 with the title: “ESTIMATION OF SURFACE AREA AND PORE VOLUME OF ACTIVATED CARBONS BY METHYLENE BLUE AND IODINE NUMBERS”Measurement of yield

[0102] The carbon yield CY is defined as the measured weight of dried carbon product divided by the calculated weight of carbon in the carbon containing start material from which the carbon product is obtained.Measurement of the concentration of zinc in the filtrate

[0103] The concentration of zinc in the filtrate was measured with a titration with EDTA 0.1 N with Eriochromeblack-T as indicator. Procedure: Transfer zinc solution to Erlenmeyer flask; dilute to about 100 mL with distilled water, if necessary; add 2 mL of pH 10 ammonia buffer solution; add a pinch of Eriochrome Black T ground with sodium chloride (100 mg of indicator plus 20 g of analytical grade NaCI); titrate with EDTA solution till the color changes to blue and calculate the moles of Zinc ions.Measurement of Conductivity

[0104] The conductivity is measured in general as follows: 1-2 gram of Carbon sample is placed into a vertical PVC tube with a steel plate as bottom. Then a bolt is screwed through a nut compacting the carbon sample between the steel plate bottom and the bolt. The bolt is tightened by hand until hand locked. The electric resistance (Ohm) is measured between two electrodes placed on both sides of the carbon sample on the bolt and on the bottom of the cylinder. The electrical resistance, length and diameter of the Carbon bed is measured. The Conductivity in S / m is calculated with the formula below.Conductivity(SZm) = L / ((Ri-Ro)*3.14*(d / O.5)2)L= length of compressed carbon bed d= diameter of compressed carbon bed Ri= Electrical resistance of compressed carbon bed Ro=Electrical resistance of nut and bolt without carbon bedMeasurement of Capacitance

[0105] Capacitance was measured on a homemade symmetric EDLC system by bringing about 100 mg of carbon material containing about 6wt% of PVA glue on a 100cm2nickel plate by using a 20% carbon / 1 ,2%PVA slurry in demi water. Plates are dried at 70°C and are pressed together(1 ,9Nm) after drying with a paper layer in between and placed in a 1 M Na2SO4 in water electrolyte.

[0106] After 800 cycles of charge / discharge curves (30s Charge at 1.3V, 60 s discharge over 100 Ohm) the Capacitance was measured expressed as F / g and compared to a commercial standard Kuraray YP-50F. Capacitance of Kuraray YP-50F was measured 33 F / g.Materials used

[0107] ZnCh anhydrous(from Sigma, 31650-M); Cellulose (from Sigma C6288); graphene oxide (from Merck 763705); graphite flakes (from Sigma, 332461); FeCI3 anhydrous (from laboratorium discounter.nl, CAS No. [7705-08-0]); Glucose (from Merck G8270).Comparative Examples CA - CB

[0108] Comparative example CA and CB are Raman measurements on commercially available samples: CA: crystalline layered carbon (Pure Graphite from Sigma, 332461) and CB: amorphous carbon (from Kuraray) was measured with as described above.Comparative examples CD - CE

[0109] Comparative examples CA and CB show the boundaries of a very high and very low degree of graphitization (DOG) of commercial “pure” graphite having DOG = 0.88 and “amorphous” active carbon having DOG = 0.33. The DOG value is expected to range between that of the “pure” graphite and amorphous carbon, so the higher the DOG the more it looks like pure graphite. It is a qualitative value of the amount of graphite formed in the carbon product but is not to be taken quantitative.Comparative examples CD - CE represent data taken from literature described above: Ref 1 is Dohyung Kang, Ref 2 is Perondi, Ref.3 is Deepti Krishan. These prior art references also describe graphitisation processes and report Raman measurements from which the DOG can be derived (wherein DOG is 1 / (1 +ld / lg)). Prior art Ref 1 describes carbonisation of methane in eutectic salts at extremely high temperatures and very long times resulting in low CY and low DOG. Prior art Ref 2 describes carbonisation of cellulose in eutectic salts in an oven. Despite the high temperatures and very long time the carbon yield CY is low and the DOG is not very high. Prior art Ref 3 describes Graphene Oxide Assisted carbonisation of cellulose by microwave heating without use of a salt. The graphene oxide is too expensive to be practically feasible and nevertheless the CY was only 10 wt% which is very low compared to the present invention and the conductivity is low compared to obtained values of the measured carbon products of the invention.Example Ex1

[0110] A reaction mixture was prepared by mixing 10 g of Glucose, 10 g of anhydrous ZnCh and 2 g of VXC-72R (Carbon-Black) in a 150 ml Pyrex beaker. Over this beaker a 600ml Pyrex beaker was placed and the air in the beakers was replaced with Nitrogen. This set-up was heated in a microwave oven at low heating rate (100 Watt) for 10 min. During this time a Carbon-foam was formed caused by the reaction between the different components and the expulsion of steam formed by the carbonization of the glucose. After cooling down the carbon foam was milled for 30 sec in a coffee mill and mixed with 5 times the sample weight of D-water and stirred for 15 min at 50°C. Then the obtained product was filtered over a 0.45-micron nylon filter and washed with 10 times the sample weight of D-water. The Filter cake was mixed with 5 bed-volumes of Demi water, and the pH was adjusted to<2 and stirred for 15 min at 50°C. Then the obtained product was filtered over a 0.45- micron nylon filter and washed with 10 times the sample weight of D-water. The Filter cake was again mixed with 5 bed-volumes of Demi water, and the pH was adjusted to <1 , and stirred for 15 min at 50°C. Then the obtained product was filtered over a 0.45-micron nylon filter and washed with 10 times the sample weight of D-water. All filtrates were clear. The Washed filter-cake was dried at 120°C until constant weight, l-number of the dried carbon product was 370 mg / g, the MB-n umber was 199 mg / g, the Conductivity was 8.4 S / m, the Oxygen content was 14 wt%, the DOG was 0.59, and the Carbon yield was 80 wt%.Example Ex1a and Ex1b

[0111] 2 g of the end-product of Ex1 was weighed in a 10 ml tube with a loose cap. Air in tube was replaced with Nitrogen. The tube was placed in a microwave oven and was heated for 30 sec at 800 Watt to produce carbon product Ex1 a. A consecutive interval of microwave heating was applied on carbon product Ex1 a for 60 sec at 800 Watt to produce carbon product Ex1 b. The temperature in Ex1 , 1 a and 1 b was measured using an Infrared camera; the highest temperature in Ex1 was 200°C. The highest temperature in the additional microwave heat treatment in Ex1 a and Ex 1 b was 300°C.Conductivity was 9.4 S / m, Oxygen content was 9 wt%, DOG was 0.63, and Carbon yield was 75 wt% for sample a. Conductivity was 72.9 S / m, Oxygen content was <5 wt%, DOG was 0.67. for sample b.

[0112] It is noted that the carbon yield after post-heating in this and all following examples is the cumulative carbon yield after the first carbonisation step and the post-heating step; i.e the weight of the carbon product after post-heating post-heating divided by the theoretical carbon content in the carbon containing starting material.Example Ex2

[0113] A reaction mixture of 30g Glucose, 30g ZnCh and 6g VXC-72R (Carbon-Black) was prepared and homogenized with a spatula for 1 minute in a 500 ml Quartz beaker with a loose tap, to ensure that gas could escape but no oxygen would get in. The air in the beaker was replaced by Nitrogen. Carbonization, milling, washing, and drying was carried out according to the method as described in Ex1 with the exception that MW power was 350W for 10 min. All filtrates were clear. I- number of the dried carbon was 600 mg / g, MB-number was 231 mg / g, Conductivity was 4 S / m, Oxygen content was 2.8 wt%, and Carbon yield was 92 wt%.Example Ex2a, b, c,

[0114] Respectively 3.0, 3.9, and 1 .8 g of the end product of Ex2 was weighed in a 50 ml Quartz beaker. Air in beaker was replaced by Nitrogen, and heated in a MW for respectively 3, 6, and 15 min at 350W. After 3 min the sample began to glow indicating a temperature between the 600 and 900°C. DOG of sample a was 0.51 . l-number was 760 mg / g, MB-number was 262 mg / g, Conductivity was 19 S / m, Oxygen content was 0.9 wt%, and Carbon yield was 84 wt% for sample Ex2a. l-number was 750 mg / g, MB-number was 228 mg / g, Conductivity was 46 S / m, Oxygen content was 0.8 wt%, and Carbon yield was 84 wt% for sample Ex2b. l-number was 750 mg / g, MB-number was 228 mg / g, Conductivity was 46 S / m, Oxygen content was 0.8 wt%, and Carbon yield was 78 wt% for sample Ex2c. Capacitance was respectively 14.7, 16.7, and 22.0 F / g for simple Ex2a, b, and c.Example Ex2d, e,

[0115] Respectively 2.1 , and 1 .5 g of the end product of Ex2 was weighed in a 50 ml Quartz beaker. Air in beaker was replaced by Nitrogen and heated in an oven for 90 min (including 30 min heating up) at respectively 600 and 800°C under nitrogen, l-number was 750 mg / g, MB-number was 228 mg / g, Conductivity was 46 S / m, Oxygen content was 2.8 wt%, and Carbon yield was 80 wt% for sample Ex2d. l-number was 780 mg / g, MB-number was 257 mg / g, Conductivity was 62 S / m, and Carbon yield was 75 wt% for sample Ex2e. Capacitance was 1 1 F / g for sample Ex2d.

[0116] Ex2 shows that in the first carbonisation step a very high CY and low OC could be obtained. After post-heating (Ex2a-c) with microwaves for a time as short as 3-12 minutes resulted in very high conductivity whilst also achieving a high porosity (high I and MB number) and capacitance CA. Ex2a- 2c compare MW heating with oven heating in Ex2d-e. This shows that oven post-heating can also result in good properties but after much longer times. Ex2d compared to Ex2e shows that a heating temperature in the oven is preferably higher than 600°C or even 700°C for at least 60 min, preferably at least 75 minutes.Example Ex3

[0117] A reaction mixture of 30g Glucose, 30g FeCH and 6g VXC-72R (Carbon-Black) was prepared and homogenized with the speed-mixer for 30 sec. Sample was placed in a 500 ml Quartz beaker. Air in beaker was replaced by Nitrogen, and sample was carbonized, milled, washed and dried according to the method described in Ex2. Filtrates were clear but greenish due to iron chloride salts, l-number of the dried carbon was 485 mg / g, MB-numberwas 113 mg / g, Conductivity was 4.6 S / m, DOG was 0.52, and Carbon yield was 85 wt%.

[0118] Ex3 shows that the process also works with FeCh as the salt although the carbon yield and porosity is lower.Example Ex4

[0119] A reaction mixture of 15g Glucose, 17g ZnCh and 3g VXC-72R (Carbon-Black) was prepared and homogenized with a spatula for 1 minute in a 500 ml Quartz beaker under nitrogen. Sample was carbonized for 45 min at 700°C in an oven and milled, washed, and dried according to the method described in Ex2. Filtrates were clear, l-number of dried carbon was 920 mg / g, MB- number was 324mg / g, Conductivity was 16 S / m, DOG was 0.51 , and Carbon yield was 56 wt%. Capacitance was 18.5 F / g.

[0120] Ex4 is a comparative example because heating is done with an oven instead of with microwaves. Ex4 shows that a reasonably good DOG and CO can be obtained but the carbon yield is low CY.Example Ex5

[0121] A reaction mixture of 10g Glucose, and 1g VXC-72R (Carbon-Black) was prepared and homogenized with a spatula for 1 minute in a 50 ml Quartz beaker under nitrogen. Sample was carbonized, milled, washed, and dried according to the method described in Ex2, but only 5 min at 230W MW. Filtration was bad and filtrate was brown, l-number of dried carbon was 90 mg / g, MB- number was <10 mg / g, Conductivity was 19 S / m, and Carbon yield was only 25 wt%.

[0122] Ex5 is a comparative example because the mixture contains no salt. The microwave heating at 230W gives brownish filtrate and a very low carbon yield.Example Ex6

[0123] Carbonization, milling, washing, and drying was carried out as described in Ex2, except with 120 W MW for 16 min. All filtrates were clear, l-number of the dried carbon was 275 mg / g, MB-number was 123 mg / g, Conductivity was 0.8 S / m, Oxygen content was 18.7 wt%, DOG was 0.67, and Carbon yield was 81 wt%.

[0124] Compared to Ex1 and Ex3, the Mw power was lower and the time was longer. The carbon yield and the DOG level was good, but the oxygen content was much higher, and the conductivity was also lower.Example Ex6a-c,

[0125] Respectively 5.0, 5.0, and 1 .4 g of the end product of Ex6 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen, and heated in a MW for respectively 0.5, 1 , and 2 min at 700W. After 1 min the sample began to glow indicating a temperature between the 600 and 900°C. l-number was 264 mg / g, Conductivity was 2.7 S / m, and Carbon yield was 80 wt% for sample Ex6a. l-number was 500 mg / g, MB-numberwas 60 mg / g, Conductivity was 11 S / m, and Carbon yield was 71 wt% for sample Ex6b. l-number was 700 mg / g, MB-numberwas <10 mg / g, Conductivity was 130 S / m, and Carbon yield was 68 wt% for sample Ex6c. Capacitance of sample Ex6c was 8.0 F / g.

[0126] Ex6a-c show that on post-heating, the mesopores collapse which is also detrimental to capacitance. The CO can be high after long go high but at expensive of CY and CA. This shows in comparison with Ex1 the preference that the oxygen content of the carbon product obtained afterthe carbonisation step is low (preferably <10 or even below 5 wt%) because the post-heating (at high power of 700 W) results in damaging of the structure.Example Ex7

[0127] A reaction mixture of 30g Glucose, 30g ZnCh and 3g Ketjenblack EC-600-JD was prepared and homogenized with the speed-mixer for 30 sec and carbonized, milled and washed / filtered, and dried like described in Ex2. All filtrates were clear, l-number of the dried carbon was 1200 mg / g, MB- number was 347 mg / g, Conductivity was 2.3 S / m, DOG was 0.53, and Carbon yield was 79 wt%.Example Ex7a

[0128] 8.0 g of the end product of Ex7 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen and heated in a MW for 20 min at 350W. After a few min the sample began to glow indicating a temperature between the 600 and 900°C. l-number was 1150 mg / g, MB- number was 327 mg / g, Conductivity was 146 S / m, DOG was 0.43, and Carbon yield was 63 wt% for sample Ex7a. Capacitance was 25.0 F / g.

[0129] Ex7 is comparable to Ex2 and Ex6 except that different carbon black was used having a higher conductivity, so less of it is needed. The CY was significantly lower, but l / MB (porosity) was higher. It is observed that low yield correlates with high porosity. Then on relatively mild post-heating at 350W (Ex7a) a carbon product is obtained having high porosity, and also high CO and CA.Example Ex8

[0130] Ex 7 was copied with the only difference that instead of 3g Ketjenblack we have added 3g of the end-product of Ex7a. All filtrates were clear, l-number of the dried carbon was 1200 mg / g, Conductivity was 0.07 S / m, and Carbon yield was 87 wt%.Example Ex8a

[0131] 8.0 g of the end product of Ex8 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen and heated in a MW for 20 min at 350W. After a few min the sample began to glow indicating a temperature between the 600 and 900°C. l-number was 1250 mg / g, MB- number was 351 mg / g, Conductivity was 95 S / m, DOG was 0.52, and Carbon yield was 70 wt% for sample Ex8a. Capacitance was 25.5 F / g.

[0132] Example 8 differs from Ex7 only in that, instead of purchased conductive carbon, the carbon product obtained by the carbonisation process of the invention can be used as the microwave absorbing material. The CY was even a bit higher. Post-heating experiment Ex8a shows good CO and CA and porosity.Example Ex9

[0133] A reaction mixture of 20g Sawdust, 23g ZnCI2 and 4g VXC-72R (Carbon-Black) was prepared and homogenized with the speed-mixer for 30 sec and carbonized, milled, washed / filtered, and dried like described in Ex2. All filtrates were clear. Conductivity was 0.65 S / m, DOG was 0.53, and Carbon yield was 83 wt%.Example Ex9a

[0134] 8.6 g of the end product of Ex9 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen and heated in a MW for 20 min at 350W. After a few min the sample began to glow indicating a temperature between the 600 and 900°C. l-number was 530 mg / g, MB- number was 192 mg / g, Conductivity was 76 S / m, DOG was 0.52, and Carbon yield was 66 wt%. Capacitance was 10.0 F / g.

[0135] Ex9 shows that good CY and DOG could be achieved also for wood as a starting material. After post-heating a good CO and reasonably good CA and porosity is obtained.Example Ex10

[0136] 7.5 g Sawdust is mixed with 22.5g ZnCh, 30g FeCH, and 75g Demi water into a homogeneous mixture in a 250ml Pyrex beaker. Mixture is stirred for 2 hrs at 80°C on a hotplate. When too much water is evaporated to maintain stirring, then a small amount of water was added to compensate for the evaporated water. Then the beaker is placed in a fan oven at 120°C for 2 hrs where the slurry is converted in partly carbonized thick foamy sludge. The sludge is brought into a 500 ml Quartz beaker with a loose tap and air inside was replaced with Nitrogen. Beaker was heated for 45 minutes in a MW at 230W to slowly evaporate the excess of water, and then for 10 min at 350W. After cooling down the carbon foam was milled for 30 s in a coffee mill and mixed with 5 times the sample weight of D-water and stirred for 30 min at 80°C. Then filtered over a 0.45 micron nylon filter and washed with 10 times the sample weight of D-water. Filter cake was mixed with 5 bed-volumes ofDemi water and the pH was adjusted to< 1 and stirred for 30 min at 80°C. Then filtered over a 0.45 micron nylon filter and washed with 10 times the sample weight of D-water. Filter cake was mixed with 5 bed-volumes of Demi water and the pH was adjusted to<1 and stirred for 30 min at 80°C. Then filtered over a 0.45 micron nylon filter and washed with 10 times the sample weight of D-water.Filtercake was dried until constant weight in a fan oven at 120°C. l-numberwas 2000 mg / g, MB- number was 614 mg / g, Conductivity was 1.2 S / m, and Carbon yield was 62 wt%.Example Ex10a

[0137] 0.7 g of the end product of Ex10 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen and heated in a MW for 5 min at 120W, 5 min 350W, and finally 1 min 700W. Only at 700Wthe sample began to glow indicating a temperature between the 600 and 900°C. l-number was 2150 mg / g, MB-number was 685 mg / g, Conductivity was 10.4 S / m, and Carbon yield was 59 wt%.Example Ex11

[0138] 7.5 g Sawdust is mixed with 22.5g ZnCh, 30g FeCH, 1 .5g VXC-72R (Carbon-Black) and 75g Demi water into a homogeneous mixture in a 250ml Pyrex beaker. Mixture is stirred for 2 hrs at 80°C on a hotplate. When too much water is evaporated to maintain stirring, then a small amount of water was added to compensate for the evaporated water. Then the beaker is placed in a fan oven at 120°C for 2 hrs where the slurry is converted in partly carbonized thick foamy sludge. The sludge is brought into a 500 ml Quartz beaker with a loose tap and air inside was replaced with Nitrogen.Beaker was heated for 20 minutes in a MW at 230Wto slowly evaporate the excess of water, and then for 10 min at 350W. Sample was milled, washed and dried as described for Ex10. l-number was 1190 mg / g, MB-number was 373 mg / g, Conductivity was 1 .5 S / m, and Carbon yield was 62 wt%.Example Ex11a

[0139] 1 .3 g of the end product of Ex11 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen and heated in a MW for 2.5 min at 700W. After 1 min the sample began to glow indicating a temperature between the 600 and 900°C. l-numberwas 1240 mg / g, MB-number was 400 mg / g, Conductivity was 21 S / m, and Carbon yield was 57 wt%.Example Ex12

[0140] 7.5 g Sawdust is mixed with 45g ZnCI2, and 115g Demi water into a homogeneous mixture in a 250ml Pyrex beaker. Mixture is stirred for 2 hrs at 80°C on a hotplate. When too much water is evaporated to maintain stirring, then a small amount of water was added to compensate for the evaporated water. Then the beaker is placed in a fan oven at 120°C for 2 hrs where the slurry is converted in partly carbonized thick sludge (no foam). The sludge is brought into a 500 ml Quartz beaker with a loose tap and air inside was replaced with Nitrogen. Beaker was heated for 20 minutes in a MW at 230Wto slowly evaporate the excess of water, and then for 5 min at 700W. Sample was milled, washed and dried as described for Ex10. l-numberwas 1437 mg / g, MB-number was 434 mg / g, Conductivity was 0.2 S / m, and Carbon yield was 69 wt%.Example Ex12a

[0141] 1 .2 g of the end product of Ex12 was weighed in a 50 ml Quartz beaker with loose tap, air was replaced with Nitrogen and heated in a MW for 5 min at 700W. After 1 min the sample began to glow indicating a temperature between the 600 and 900°C. l-numberwas 1350 mg / g, MB-number was 404 mg / g, Conductivity was 17.5 S / m, and Carbon yield was 60 wt%.

[0142] Examples Ex10 -Ex12 differ from previous examples in that they use a wet Pretreat in ZnCL or ZnCh / FeCh with and without added conductive carbon. It was found that addition of conductive carbon is not necessary when using a wet pretreat step. It is believed that in the wet pretreat microwave absorbing material is formed. The yield is relatively low and the porosity is high in the carbonisation step. Then in the post-heating step a mild post-heating results in retaining very high porosity which is good for high capacitance and also a high CO could be obtained. Longer postheating will further increase the CO. Ex10-12 show better properties than Ex9, which shows the benefit of a wet pretreat.ref 1 is Dohyung Kang, ref 2 is Perondi, ref.3 is Deepti Krishan, CB is Cabot VXC 72R, CB(1 ) is Kejenblack EC-600JD, CB(2) is CP-2 endproduct

[0143] The examples further show that the process of the invention has the advantage that it operates very fast and efficiently and does not rely on seeding with the very expensive GO and nevertheless results in a carbon product with desirable properties and can be flexibly adapted to produce the properties in view of the envisaged applications. The examples of the invention show that a very high degree of graphitization can be achieved, with a very high carbon yield a high porosity as reflected by the I and MB number and that also a very high conductivity and capacitance can be reached.

Claims

WHAT IS CLAIMED IS:

1. A process for the preparation of a carbon product having a high degree of graphitization, comprising the steps of a. preparing a mixture comprising a carbon containing starting material, a salt and a microwave or induction radiation absorbing material, preferably conductive carbon, i. wherein the carbon containing starting material is a carbohydrate or hydrocarbon containing starting material, ii. wherein the salt comprises one or more salts selected from the group consisting of ZnCL, MnCL, FeCh, AlCh, MgCh, CaCh, SbCh,, b. Carbonising the carbon containing starting material to form the carbon product i. by heating with microwaves or induction radiation, ii. preferably at temperatures between 200 and 1000°C, preferably between 300 and 800°C, more preferably between 400 and 600°C,Hi. in an atmosphere free of oxygen (O2), iv. in an open reactor evaporating and removing water present or formed during carbonisation, v. converting the carbon containing starting material to the carbon product having a degree of graphitization DOG of at least 45% wherein degree of graphitization is defined as lg / (ld+lg) wherein Ig and Id are respectively Raman adsorption intensities in band G at 1580 cm- 1and Band D in the range of 1330-1340 cm-1, c. Separating the carbon product from the one or more salts.

2. The process according to claim 1 , wherein the one or more salts comprise at least 50 wt.%, more preferably at least 70 wt%, even more preferably at least 80 wt% and most preferably at least 95 wt% ZnCh relative to the total amount of salts, with the remainder of the salt being one or more other metal halide salts, preferably AlCh, MnCh, SbCh, MgCh, CaCh or FeCh and more preferably FeCh.

3. The process according to anyone of claims 1 or 2, wherein the carbon containing starting material comprises a hydrocarbon selected from the group of paraffins, ethylene- or propylene containing polymers and lignin or, more preferably, the carbon containing starting material comprises a carbohydrate selected from the group of monosaccharides, oligosaccharides, polysaccharides and most preferably cellulose or glucose or mixtures thereof and preferably in an amount of at least 50, 70, 80 or even at least 90 wt% relative to the total weight of the carbon containing starting material.

4. The process according to claim 3, wherein the carbon containing starting material is carbohydrate containing starting material preferably wood, saw-dust, paper, cotton or empty fruit bunch, preferably finely comminuted.

5. The process according to anyone of claims 1 - 4, wherein in step a) the mixture comprising the carbon containing starting material, the salt and the radiation absorbing material, preferably conductive carbon, comprises less than 5 wt% water relative to the total weight of the mixture, preferably less than 2 wt% and more preferably less than 1 wt% water and preferably the mixture is dried at a temperature below 120°C before the carbonisation step in case the water content in the mixture is higher than 5 wt%.

6. The process according to anyone of claims 1 - 5, wherein the mixture of the carbon containing starting material, the salt and the radiation absorbing material, preferably conductive carbon, is prepared by a. adding a conductive carbon to a mixture of the carbon containing starting material and the salt, or by b. mixing carbon product obtained by step b) or c) of the process of claim 1 with a mixture of the carbon containing starting material and the salt, c. partially carbonise the carbon containing starting material, preferably carbohydrate containing starting material, forming the radiation absorbing material in-situ by i. reparing a slurry of a mixture comprising the carbon containing starting material and the salt in water and heating the slurry at a temperature between 50 and 150°C to partially carbonise the carbon containing starting material, ii. wherein the amount of water in the slurry is preferably at least 50 wt% relative to the total weight of the slurry,Hi. drying the slurry before carbonisation step b). d. carbonise a carbohydrate containing starting material forming radiation absorbing material in situ by a first wet carbonisation step comprising i. Contacting the carbohydrate containing starting material with a hydrated salt wherein the hydrated salt comprises one or more hydrated salts selected from the group consisting of ZnCh, MnCh, FeCh, AlCh, MgCh.CaCH, SbCh hydrates, wherein preferably the water content is more than 1 wt% and preferably below 30wt%, ii. Carbonising the carbohydrate containing starting material in mixture with the hydrated molten salt by heating at temperatures between 100 and 300°C, preferably between 125 and 275°C, more preferably between 150 and 250°Cin a closed reactor system, preferably in an oven or with microwaves, in an atmosphere free of oxygen (O2), wherein either11.1) the carbonisation is partial and the obtained mixture of salt and carbohydrates that are partially carbonized to in situ form radiation absorbing material is dried before carbonisation step b) OR11.2) the carbonisation is done to form a carbon product having a degree of graphitization DOG of at least 45%, preferably at least 55% and an oxygen content between 20 and 40 wt%, followed by separating and drying the obtained carbon product, then optionally subjecting to a deoxygenation step to reduce oxygen content and then adding the obtained dried carbon product to the carbon containing starting material and salt.

7. The process according to anyone of claims 1 - 6, wherein the amount of carbon containing starting material is between 5 and 80 wt.%, preferably between 10 and 70 wt, more preferably between 30 and 60 wt% relative to the total weight of carbon containing starting material and the salt and wherein the conductive carbon is preferably present in an amount between 5 and 30 wt%, preferably between 7 and 28 wt% more preferably between 10 and 25 wt% relative to the weight of the carbon containing starting material.

8. The process according to anyone of claims 1 to 7, wherein a. a ratio of the salt and the carbon containing starting material is between 0.5 and 50, preferably between 0.5 and 30, more preferably between 1 and 10, b. a ratio of the conductive carbon to the carbon containing starting material is between 0.01 and 1 , preferably between 0.05 and 0.5, more preferably between 0.07 and 0.2 c. most preferably the ratios of the carbon containing starting material to the salt to the conductive carbon are around 1 :1 :0.1 .

9. The process according to anyone of claims 1 - 8, wherein after the carbonisation step b) the carbon product is separated from the one or more salts by washing with water, preferably at a temperature between 50 and 90 °C and preferably by refluxing in water in a Soxhlet type of extraction.

10. The process according to anyone of claim 9, wherein after the carbonisation step b) the carbon product is separated from the one or more salts by washing with water with acidified water, preferably having a pH below 4, preferably below 3, more preferably below 2 and most preferably below 1 .11 .The process according to claim 9 or 10, wherein the washing is stopped before completely removing the salt to intentionally leave a residual amount of the metal-halide salt in the formed carbon product , wherein the amount of residual salt is between 0.01 - 20 wt%, preferably 0.02 - 15 wt%, more preferably 0.5 - 10 wt% of the total weight, optionally comprising a further step wherein the residual metal-halide salt is converted to it’s metaloxide and / or metal hydroxide, preferably by addition of a strong base, which preferably is KOH or NaOH, preferably ZnCh converted to ZnO and / or Zn(OH)2.

12. The process according to anyone of claims 1 - 11 , wherein the carbon product obtained in process of anyone of claims 1 - 11 is subjected to a post-treatment step d) to reduce the oxygen content of the carbon product, optionally after having been exfoliated.

13. The process according to claim 12, wherein the carbon product obtained in process of anyone of claims 1 - 11 has an oxygen content between 1 and 10 wt%, preferably between 1 and 15 wt%, more preferably between 1 and 10 wt% and even more preferably between 1 and 5 wt% and in post-treatment step d) the oxygen content of the carbon product is reduced to below 5 wt%, preferably below 3 wt% and more preferably below 2 wt% and most preferably below 1 wt%.

14. The process according to claim 13, wherein the method to reduce oxygen content in posttreatment step d) is chemical reduction, thermal reduction, hydrothermal / solvothermal reduction, electrochemical reduction or photocatalytic reduction, preferably the thermal reduction is done by post-heating the, preferably washed and dried, carbon product to a temperature above 200°C, preferably above 250°C, more preferably above 300°C, more preferably at a temperature between 300°C and 1500°C, even more preferably 400°C to 1000°C, and most preferably 500°C to 900°C in oxygen free atmosphere in an open reactor, by heating in an oven or by heating with microwave or induction radiation.

15. The process according to anyone of claims 1 - 11 , wherein the carbon product obtained in process of anyone of claims 1 - 11 is subjected to a post-heating step d) by microwave radiation, at a power between 100 and 1000 Watt and preferably for a time between 1 and 20 minutes, either in one step at a power between 500 and 1000 Watt or in two or more steps using a power between100 and 500 W in a first step and a power between 500 and 1000 W in a subsequent step.

16. The process according to anyone of claims 1 - 15, wherein the carbon yield CY of the obtained carbon product, defined as the dry weight of the carbon product relative to the theoretical amount of carbon in the carbon containing starting material, is at least 40 wt%, preferably at least 50 wt% more preferably least 60, even more preferably at least 70 wt%.

17. The process according to anyone of claims 12 - 16, wherein the carbon product obtained in step d) has an MB number of at least 200, preferably at least 300, more preferably at least 400 and mostpreferably at least 600 and an I number of at least 500, preferably at least 800, more preferably at least 1000 even more preferably at least 1200 and most preferably at least 1600.

18. A carbon product obtainable by the process according to anyone of claims 1 - 17.

19. The carbon product obtainable by the process of anyone of claim 1 - 11 , having before posttreatment step d), a DOG of at least 45%, preferably at least 55 % and an oxygen atom content between 0 and 20 wt%, preferably between 0 and 10 wt%, more preferably between 0 and 5 wt%, optionally comprising a residual fraction of the metal halide salt and / or it’s metaloxide or metal hydroxide as electrolyte, preferably ZnCh and / or ZnO or Zn(OH)220. The carbon product obtainable by the process of anyone of claims 12 or 17, having after posttreatment step d), a. an oxygen atom content between 0 and 5 wt%, preferably between 0 and 3 wt%, more preferably between 0 and 1 wt%, b. a conductivity of at least 20, preferably at least 50, 75 or even at least 100 S / m, c. a capacitance of at least 15, preferably at least 20, more preferably at least 25 F / g d. an MB number of at least 200, preferably at least 300, more preferably at least 400 and most preferably at least 600 and e. an I number of at least 500, preferably at least 800, more preferably at least 1000 even more preferably at least 1200 and most preferably at least 1600.

21. Use of the carbon product according to claim 19 as a precursor for the manufacture of Graphene Oxide, Graphene or Carbon Fibers, or the use of the carbon product according to claim 20 for the manufacture of electrode materials or electrodes, capacitors, batteries, or conductors.

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