Method for converting carbon-containing materials in a hydratable molten salt bath - Patents.com

Abstract

The present invention relates to a method for converting carbon-containing materials, such as synthetic polymers and / or hydrocarbons, contained in waste materials and providing an effective carbonization to produce carbon and optionally hydrogen, comprising contacting and mixing the carbon-containing material with a hydratable molten salt and converting in a carbonization reactor to a reaction mixture containing a converted gas and a non-volatile converted product, which is solid carbon, recovering the converted gas and adding water or steam to the reaction mixture to rehydrate the molten salt, whereby phase separation occurs to form a non-volatile carbon-containing phase and a rehydrated molten salt phase, separating and dehydrating the molten salt phase, recycling the dehydrated molten salt and returning the steam.

Description

2. Background of the Invention

[0001] FIELD OF THEINVENTION The present invention relates to a method for converting carbon-containing materials, preferably waste materials containing hydrocarbons, such as waste oil or refinery residues, and / or synthetic polymers, preferably thermoplastic polymer-containing waste (TPW), which produces valuable, (re)usable carbon materials.

[0002] 2. Description of Related Art

[0002] In view of the environmental problems caused by plastics and the difficulty of recycling plastics, much research and development effort has been expended on converting plastics into fuels, hydrogen, carbon, and the like.

[0003]

[0003] US2015 / 0001061 describes a pyrolysis process for converting plastics to oil, including a premelt reactor to melt the plastics, pyrolysis, evaporation, and selective condensation, which produces a final, in-spec oil product.

[0004]

[0004] US2012 / 0261247 describes a pyrolysis method in which plastic materials are processed into granules or flakes, heated to melt them, and then introduced into a pyrolysis reactor to pyrolyze the molten materials to provide pyrolysis gas; the pyrolysis gas is led to a contactor having a set of liquefaction device elements, where some long-chain gas components are condensed in the elements, and the condensed long-chain materials are returned for further pyrolysis to achieve pyrolysis, and short-chain gas components are discharged from the contactor in gaseous form; the pyrolysis gas from the contactor is distilled in a distillation column to provide one or more fuel products.

[0005]

[0005] US7758729 describes a waste to fuel (WTF) process which includes a vacuum system for removing vapors from a pyrolysis heat treatment chamber which includes a series of staged temperature set points, each stage corresponding to the vaporization temperature of an individual by-product of the plastic material, and in which an inert gas is evacuated in the treatment chamber at each temperature set point to selectively remove the individual by-product corresponding to the temperature set point.

[0006]

[0006] Alamer, A., and Awaji, M., in the title "Molten Salt Pyrolysis of Waste Polystyrene" (2014), a graduate thesis from Worcester Polytechnic Institute, describe a single-pot pyrolysis technique of waste polystyrene by utilizing a eutectic molten salt mixture to achieve high styrene yields under various conditions. Molten salts are used here because they make good heat transfer media with low viscosity and eutectic molten salts have low melting temperatures. The method uses helium as an inert gas to avoid combustion and process hazards. Alamer et al. focus only on the pyrolysis step to study the effects of ternary mixture composition, temperature, etc. on pyrolysis and do not describe an economically feasible method for recovering hydrogen and carbon from such a process.

[0007]

[0007] US4104056 describes a method for effectively using coal as a fuel, which includes alternating hydrogenation and oxidation of coal in a molten salt. The method includes dissolving coal in the molten salt, introducing steam under hydrogenation conditions to produce volatile hydrocarbons using a very short residence time to prevent thermal decomposition, and then adding an oxidizing gas to the molten salt containing the dissolved non-volatile residue under fuel oxidation conditions to produce heat. The molten salt used here is a eutectic molten salt mixture containing a eutectic mixture of zinc chloride and other metal halides.

[0008]

[0008] WO2020 / 248914 describes the pyrolysis of waste plastics by directly heating them with a hot liquid to undergo a pyrolysis reaction in the hot liquid at 200°C to 500°C to produce pyrolysis oil (by condensation of pyrolysis gases in a liquefier) ​​and slag. The hot liquid is a molten metal or metal alloy, in particular lead or a lead alloy. Zinc chloride is also mentioned.

[0009]

[0009] CN110538637 describes a method for converting polyethylene terephthalate plastic into carbonaceous nanostructured material, in which in step a) a salt or salt mixture is used to heat the plastic, and then in step b) washing and desalting are carried out to obtain a carbonaceous nanostructured material. The obtained carbonaceous nanostructured material is then heated in a protective rare gas atmosphere or in a molten salt medium at a temperature of 450°C to 1300°C to obtain a nanostructured carbon material. The salt mentioned is ZnCl at a heating temperature of 270 to 450°C. 2 Includes.

[0010]

[0010] WO2018141911A describes a method for converting hydrocarbons into hydrogen and a separate carbon phase, in which the hydrocarbons, in particular natural gas, are contacted with a molten salt at very high temperatures, above 500°C.

[0011]

[0011] US2014 / 135510 describes a method for converting polysaccharides, particularly lignocellulosic biomass materials, in inorganic molten salt hydrates into platform chemicals, comprising the steps of dissolving, hydrolyzing to monosaccharides, hydrogenating to sugar alcohols, and dehydrating to anhydrosugars.

[0012] Chambers et al., in their paper entitled "Polymer waste reclamation by pyrolysis in molten salts" (1984), Industrial & Engineering Chemistry Process Design And Development, 23(4), 648-654, describe a method for pyrolysis of polymer waste feed derived from the reclamation of automobile shredder waste, including shredded tires, plastics, and other wastes, using molten salts as the pyrolysis medium at temperatures between 380 and 570°C. The method involves grinding in liquid nitrogen. The method uses dry nitrogen as the inert gas to avoid combustion and process hazards. Therefore, the method is expensive and not practical. The resulting products are mostly chars, which are low-value products. Chambers focuses only on the pyrolysis process to study the effects of molten salt type, temperature, etc. on pyrolysis, and does not describe an economically feasible method for converting waste to hydrogen and carbon from such a process.

[0013]

[0013] The described processes have one or more of the following disadvantages: they require very high energy inputs, they may only be economically feasible at economies of scale requiring huge investments, they have unacceptable environmental impacts, they form valuable products in low yields; in particular, the yields of hydrogen and carbon are relatively low, and toxins such as diolefins, nitrosamines, polycyclic aromatic compounds, etc. may also be formed, which may end up in the gas, liquid, or aqueous phases, leading to extra costs derived from treating these toxin streams.

[0014] The object of the present invention is to provide an efficient carbonization method for converting waste feeds containing carbon-containing materials, preferably synthetic polymers and / or hydrocarbons, to produce good yields of hydrogen and carbon in an economically and environmentally attractive manner, while reducing CO 2 No or minimal CO emissions 2 This causes CO 2The goal is to provide a way to make overall emissions negative. Summary of the Invention

[0015] The present invention relates to a method for converting a carbon-containing material, the method comprising the steps of: a. contacting and mixing a carbon-containing material with a hydratable molten salt; b. Carbonizing the carbon-containing material in molten salt under carbonization conditions i. At a temperature T1 of 200° C. to 500° C., preferably 200° C. to 400° C., more preferably 200° C. to 350° C., ii. at a pressure of preferably less than 50 bar, more preferably less than 15 bar, even more preferably less than 10 bar, and most preferably less than 1 bar; iii. There is no oxygen; iv. the hydratable molten salt is at least partially dehydrated; v. The presence of water vapor as an inert gas vi. forming a reaction mixture comprising the converted gas and non-volatile converted products comprising carbon in the molten salt; converting in a reactor under c. recovering the converted gas from an outlet of the reactor, optionally assisted by purging with water vapor, optionally cooling the converted gas to condense the water vapor, and recovering a dry converted gas; d. adding water or steam to the reaction mixture to cool the reaction mixture and rehydrate the molten salt, thereby causing phase separation to form a non-volatile carbon phase and an at least partially rehydrated molten salt phase; e. separating the non-volatile carbon phase from the at least partially rehydrated molten salt phase; f. heating the resulting partially rehydrated molten salt phase to form at least partially dehydrated molten salt and water vapor, preferably in step b) or in a separate step; g. using the at least partially dehydrated molten salt phase in step a) or b); h. Preferably, in the process, the water vapor obtained in step f) is preferably used for purging oxygen from the reactor in step a) and / or for hydrating the molten salt in step d), These problems are addressed by providing a method comprising the steps of: i. optionally separating inorganic matter in a separation step, wherein inorganic solids are separated from the molten salt by density difference, preferably after step a) and before step b).

[0016] It has been found that in the process of the present invention, carbon-containing materials are effectively and efficiently converted to carbon, and, depending on the type of carbon-containing material, also to hydrogen, which are valuable products. The resulting dry converted gas is H 2 %, preferably less than 5 wt. %, and even more preferably less than 3 wt. % of hydrocarbons having 2 or more carbon atoms, which differs from pyrolysis processes which primarily result in higher hydrocarbons (including primarily C5-C20 hydrocarbons) that are liquid at room temperature after condensation.

[0017] The advantage of the method of the invention over other methods of converting carbonaceous waste, such as pyrolysis or steam cracking, is that the method can be carried out at low pressures and relatively low temperatures. Pyrolysis is typically carried out at temperatures above 450° C., producing liquid oil and gas. Steam cracking pyrolysis is carried out at temperatures above 350° C. and high pressures up to 20 bar, producing liquid oil and gas. Hydrothermal conversion methods are carried out at temperatures above 300° C. and pressures above 100 bar, producing mainly solid carbon. The method of the invention can be carried out at significantly lower temperatures, even as low as 200-300° C., and in principle does not require overpressure in the carbonization reactor in step b) for the carbonization process in molten salt. Some overpressure is preferred only to prevent oxygen from entering the reactor.

[0018]

[0018] The process must be carried out in the absence of oxygen to avoid reactions with the hydrogen gas produced, which would reduce the yield of the desired hydrogen gas product, and for safety reasons. An advantage of the process of the present invention is that water vapor can be used as an inert gas. Water vapor is generated in the process by dehydrating the molten salt, condensed and reused. Thus, there is no need to use a separate inert gas, making the process simpler and cheaper. Preferably, before the conversion step b), oxygen is purged from the reactor with water vapor, and preferably also from the carbon-containing material.

[0019]

[0019] A feature of the present invention is that a hydratable molten salt is used as the only solvent medium in the process, with different degrees of hydration (different water content) in different steps of the process to provide molten salt solvents with different solvent qualities. This avoids having to use different solvents, which would make the process more complex and expensive. The hydratable molten salt and water can be recycled and reused in the process, providing a process with less environmental impact, both in terms of emissions and energy consumption.

[0020] The possibility of easily changing the solvent quality can also be used to adapt it to different feeds; for example, polymeric materials, such as those in TPW, have been found to be more difficult to carbonize than hydrocarbon materials. Thus, polymeric materials are preferably carbonized in molten salts with a very low water content, more preferably in anhydrous molten salts and at somewhat higher temperatures. Hydrocarbon materials, such as oils, can be carbonized in molten salts with a relatively high water content at lower temperatures, which is more economical in terms of energy consumption. This makes the method of the present invention very flexible for converting different types of feeds and reduces the need for pre-separation and washing steps, which are often too expensive to be cost-effective.

[0021]

[0021] A further advantage is that the process is less sensitive to water in the waste feed, which is a major advantage over previous processes that require drying after washing. Water in the waste feed hydrates the hydratable molten salt and / or is lost as water vapor from the carbonization reactor used in the process. The water content in the hydratable molten salt in step b) can be reduced by adding anhydrous molten salt.

[0022] It has been found that the present process prevents the emission of heteroatom impurities in waste streams, and in particular the emission of nitrogen and sulfur impurities as NOx and SOx gases which are very harmful to the environment and / or require additional gas cleaning steps. In the process of the present invention, the impurities are captured in the carbon produced, which may in fact have additional economic value in certain applications.

[0023] The process of the present invention also allows for the easy removal of heteroatom impurities, such as halogens, which may be present in certain plastic additives, such as flame retardants, or halogenated polymers, such as PVC.

[0024]

[0024] In particular, in the method of the present invention, it has been found that thermoplastic polymer-containing waste feed (TPW) is very efficiently carbonized in low water content molten salts, especially in anhydrous hydratable molten salts (AMS). The inventors have found that thermoplastic polymers (hereinafter also referred to as plastics) cannot be easily converted in hydrated molten salts because when the plastic melts, it tends to phase separate from the molten salt before carbonization, resulting in impaired heat transfer. TPW can be efficiently mixed, dissolved or dispersed in low water content molten salts or AMS, giving very good heat transfer efficiency. The metals of the molten salt and any additional metals dissolved in the molten salt can also provide a catalytic effect on the carbonization conversion.

[0025] Another advantage of the method of the invention is that it is relatively easy to separate inorganic contaminants from the carbonaceous waste. Thus, if the carbonaceous feed contains inorganic materials, these are preferably removed in an inorganic separation step i) in which inorganic solids are separated from the molten salt by density differences, preferably after step a) and before the carbonization step b). The hydratable molten salt has a density (approximately 0.5-1.5 g / cm) significantly greater than the density of the carbonaceous material. 3 ), the carbon-containing material floats on the molten salt separate from the denser inorganic matter, which can then be relatively easily removed with the same molten salt solvent medium used in the remainder of the method.

[0026] The method includes the steps of: 2 and carbon and any H with minimal or no production of liquid oil and / or tar. 2 The absence of tar is an important advantage compared to pyrolysis and / or vaporization methods. The exact value depends on the type of feedstock. Also, a minimal amount of toxic by-products is formed, which is also an important advantage compared to pyrolysis methods, where many small molecules (such as dioxins) are generated in the oil and water phases. In the method of the invention, these small material molecules are sufficiently converted to carbon and / or absorbed by the carbon formed in a manner that acts as an activated carbon adsorbent. The method of the invention allows for an easy and effective separation of the carbon generated by hydrating the molten salt.

[0027] The features and advantages of the present invention may be understood with reference to the following drawings. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of the method of the present invention. [Diagram 2]

[0029] FIG. 2 is a further schematic diagram of a continuous process. [Diagram 3]

[0030] FIG. 3 is a schematic diagram of heat flow in the method of FIG. Detailed Description of the Invention

[0029]

[0031] The present invention relates to a method for converting carbon-containing materials, preferably carbon-containing materials in a waste feed, preferably a waste feed comprising thermoplastic polymers (TPW) and / or a waste feed comprising hydrocarbons (HCW). Hereinafter, the carbon-containing material is also referred to as the feed or waste feed of the method.

[0030]

[0032] In a particularly advantageous embodiment of the invention, the carbonaceous waste feed is a thermoplastic polymer-containing waste (TPW), preferably comprising at least 50 wt.%, more preferably at least 60 wt.% thermoplastic polymer (TP). In addition to TP, the waste stream may also comprise organic materials different from TP, such as biopolymers, e.g. cellulose, hemicellulose, or thermosetting polymer materials. These organic materials can also be converted in the process of the invention, but they may produce undesirable by-products, e.g. chars, reducing the yield and purity of the carbon and hydrogen obtained, and additional purification steps may be required. Although thermoplastic polymers are more easily converted, the process can also convert crosslinked or vulcanized polymers. An important example of such a waste material feed is used tires. However, in order to maximize the yield of the converted products in the process and to avoid process complications and additional purification steps, the TPW preferably comprises as much thermoplastic polymer as possible. The cleaner and more homogeneous the feed, the better. Preferably, the TPW comprises at least 60 wt.%, 70 wt.%, 80 wt.%, or even more preferably at least 90 wt.% TP, and preferably less than 40 wt.%, more preferably less than 30 wt.%, even more preferably less than 20 wt.% thermosetting polymer, and preferably less than 20 wt.% other waste feed components.

[0031]

[0033] The TPW used in the present invention typically comprises one or more TPs selected from the group consisting of polypropylene, polyethylene, polyester, polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, or mixtures, copolymers, blends, or composites thereof, preferably TPs that do not contain heteroatoms O, N, or halogens, and most preferably polyolefins, taking into consideration maximizing the yield and purity of the conversion products.

[0032]

[0034] In another embodiment, the carbon-containing waste feed comprises hydrocarbons (HCW). Examples of hydrocarbon-containing waste feeds are oils, fuels, waxes, residues from oil refineries that are not pure enough to be used for their original intended purpose and further refining steps are not economically feasible. Obviously, the feed can also include both thermoplastic polymers and hydrocarbon waste materials. Examples of hydrocarbon sources are waste fossil fuel residues and tars, tar, pyrolysis oils, etc.

[0033]

[0035] The raw waste stream is preferably pretreated to remove most of the non-organic (inorganic) materials, e.g. metals, sand, etc. Hydrocarbons do not need to be removed. Organic materials from bio-based feedstocks, e.g. carbohydrates, proteins, cellulose, lignin, sugars, etc., can be converted in the process, but are not preferred. It is primarily worth separating them and recycling or reusing them. Furthermore, carbohydrates produce water during carbonization, which is not a problem but is not preferred in the process. Thus, preferably, the waste feed is purified to contain at least 60 wt% TPW and / or hydrocarbons. If municipal waste is used in the process according to the invention, it is preferably washed to remove metal parts, sand, glass, etc., and / or dried to remove water. If the waste feed contains solids, e.g. plastics, it is preferably reduced in size as much as practically possible to increase contact with the hydratable molten salt.

[0034]

[0036] The method of converting the feed includes providing a reactor and a feed, and preferably purging oxygen from the reactor and the feed with water vapor.

[0035]

[0037] Step a) of the method involves contacting and mixing the carbon-containing material with the hydratable molten salt. The contacting can be carried out in a separate step or directly in the carbonization reactor. The contacting is preferably under high shear conditions for efficient contacting, preferably in a stirred reactor.

[0036]

[0038] Step b) involves converting the carbon-containing material in the molten salt in a reactor under carbonization conditions at a temperature T1 between 200°C and 500°C, preferably between 200°C and 400°C, more preferably between 200°C and 350°C. Feeds that are more difficult to carbonize, such as polymer waste materials, are preferably carbonized at somewhat higher temperatures. In TPW, the temperature is preferably between 220°C and 450°C, more preferably between 220°C and 400°C, even more preferably between 220°C and 350°C. The conversion temperature is low compared to prior art pyrolysis processes, which is a great advantage in reducing the energy costs and the complexity of the process. A particular further advantage is that hydrogen production is promoted at low temperatures. Low temperatures are also favorable in terms of energy consumption, while high temperatures are favorable in terms of yield and speed. The optimal balance can be found by the skilled person in each case, depending on the specific composition and the final desired product.

[0037]

[0039] In principle, no overpressure is required in the carbonization reactor in step b) for the carbonization process in the molten salt. Some overpressure is preferred to prevent oxygen from entering the reactor, but preferably not more than 1-5 bar. The pressure is typically autogenous; i.e. the pressure resulting from the evaporation of water under carbonization conditions; not due to the application of external pressure. The water that evaporates during carbonization is typically removed via a pressure valve at the outlet of the carbonization reactor. For process economic reasons, the pressure is preferably not more than 50 bar, since the process can function at higher pressures, but would require expensive and unnecessary special equipment. For process economic reasons, the pressure is preferably less than 15 bar, more preferably less than 10 bar, even more preferably less than 8 or 5 bar, most preferably less than 1 bar (gauge pressure). The time of exposure to carbonization conditions is significantly longer than in pyrolysis processes. The time depends on several factors, such as the nature and size of the feed, the type of reactor used, the mixing efficiency, etc. The time is chosen to be long enough to achieve substantially complete conversion (eg, greater than 90 or 95% of the feed) to carbon and converted gases at the indicated temperature.

[0038]

[0040] In the case of zinc chloride, at high temperatures above about 290° C. and at the low pressures used in the process, the hydratable molten salt remains substantially anhydrous. Residual moisture present in the feed or water formed during the carbonization process does not hydrate the molten salt at low pressure and high temperature conditions, but evaporates as water vapor, which is removed from the reactor. During the carbonization of the organic waste in the molten salt melt, water vapor can be used as an inert gas medium, which makes the process simple and cost-effective compared to prior art processes that must use nitrogen or helium as inert gas. A particular advantage is that water vapor can be easily and continuously separated from the conversion gas by condensation, for example in a heat exchanger, and recycled in the process, which represents an environmental and cost advantage.

[0039]

[0041] The process according to the invention, step b), produces a converted gas, which in step c) is recovered from the outlet of the reactor, optionally assisted by purging with water vapor. The composition of the converted gas depends on the nature of the carbon-containing material. Hydrocarbons are converted to carbon and hydrogen. Carbohydrates are converted to carbon and water, forming little or no hydrogen. The converted gas recovered in step c) is cooled to condense the water vapor to recover water, and depending on the nature of the carbon-containing material, a dry converted gas is also recovered. The resulting dry converted gas is then condensed with H 2 %, preferably less than 5 wt. %, and even more preferably less than 3 wt. % of hydrocarbons having 2 or more carbon atoms, which differs from pyrolysis processes which primarily result in higher hydrocarbons (including primarily C5-C20 hydrocarbons) that are liquid at room temperature after condensation.

[0040]

[0042] Step d) involves adding water or steam to the carbon-containing reaction mixture to cool the reaction mixture and rehydrate the molten salt, whereby phase separation occurs between a phase containing non-volatile conversion products including carbon (referred to as NVC or carbon phase) and an at least partially rehydrated molten salt phase, optionally followed by further cooling by external cooling means. The low density, hydrophobic carbon phase floats to the surface of the more hydrophilic rehydrated molten salt (referred to as HMS) and can be easily removed. The cooling and hydration step d) is not only important to create the phase separation, but also to avoid the self-combustion of the NVC when it is separated in step e) and comes into contact with the outside air.

[0041]

[0043] Step e) comprises separating the NVC phase from the at least partially rehydrated molten salt phase. The cooling and separation steps d) and e) comprise one or more cooling and separation steps. Preferably, the reaction mixture is cooled and hydrated to a temperature TI below 200°C, preferably below 150°C. At the low temperature TI, the solid or liquid carbon phase is separated from the molten salt. The advantage of the low temperature separation step is a high yield of separated NVC. Low temperatures are also good for lowering the risk of carbon burning when in contact with air; therefore, for safety reasons, even lower temperatures, for example below 100°C, are preferred. The possibility of lowering the melting temperature of the molten salt by hydrating the anhydrous molten salt to form a molten salt hydrate, is a particular advantage of using a hydratable molten salt. Compared to a dehydrated molten salt, the low temperature, combined with the change in the solvent quality of the rehydrated molten salt, makes it relatively easy to separate the solid or liquid carbon phase.

[0042]

[0044] Cooling to a low temperature TI is preferred in terms of NVC yield. However, cooling to a relatively high temperature Th is preferred in terms of energy consumption. In an alternative embodiment, at least a part of the reaction mixture is cooled to a temperature Th above 200° C., preferably above 250° C. or even above 300° C., and optionally subjected to pressure, which is preferably applied with steam. The advantage of said high-temperature separation step is that less cooling requires less energy input in the subsequent dehydration and reheating steps. Moreover, the high temperature may allow the separation of NVC fractions with a different composition than the NVC separated after direct cooling to a low-temperature TI below 200° C.

[0043]

[0045] The reaction mixture can be cooled from the carbonization temperature T1 in one step, but also in two or more steps; a step means a temperature interval. For example, a first cooling step can be performed to a relatively high temperature Th, followed by a waiting period, for example to allow phase separation, a transfer to another reactor, a separation step or a purification step, followed by a second further cooling step.

[0044]

[0046] It may be a disadvantage that at high temperatures Th not all NVC will separate from the molten salt. Therefore, when a high temperature Th is used, it is preferably followed by a lower temperature separation step. Optionally, only a portion of the reaction mixture is cooled to a temperature Th and the remaining portion is cooled to TI.

[0045]

[0047] In a further alternative embodiment, two or more subsequent cooling and separation steps are applied at different temperatures, preferably initially at a high temperature Th and then at a low temperature TI, to obtain two or more different NVC fractions with different compositions. The advantage of this alternative process is that two or more different NVC fractions with different compositions can be obtained with high quality products.

[0046]

[0048] After separation of the NVC phase from the rehydrated molten salt phase, the resulting at least partially rehydrated molten salt phase produced in step e) is heated to at least partially dehydrate the molten salt, which can be done in a separate heating step or directly under carbonization conditions in carbonization step b) or during contacting step a).

[0047]

[0049] Preferably, the heating in step f) is to a temperature T2 above 250° C., preferably above 300° C. However, too long exposure to high temperatures risks thermal decomposition of the molten salt with substantial formation of HCl, HClO, etc. It is therefore preferred to apply a vacuum and use lower temperatures in step f), which can be more conveniently performed in a separate heating step. The inventors have shown that the dehydration of zinc chloride under (deep) vacuum and at relatively mild temperatures leads to ZnCl without the formation of substantial amounts of HCl. 2It has been found that the at least partially rehydrated molten salt can be dehydrated and concentrated to nearly 100%. Thus, in step f), the at least partially rehydrated molten salt is preferably dehydrated by applying heating and vacuum at a pressure of less than 100 Pa (medium vacuum), more preferably less than 0.1 Pa (high vacuum), even more preferably less than 0.0001 Pa (ultra-high vacuum), preferably at a temperature of less than 175°C, more preferably less than 150°C, and more than 100°C, preferably more than 120°C, optionally adding a metal oxide before or during heating, the metal being preferably the same as that of the molten salt. As an alternative or in addition to applying a vacuum and low temperatures, the formation of HCl (or HBr) can be suppressed by adding a metal oxide that reacts with HCl or HBr; in the case of a zinc chloride molten salt, zinc oxide is preferably added.

[0048]

[0050] A particular advantage is that the solvents for all steps are molten salts with different water contents, which only require the addition and removal of water, which can be used as inert purge gas as steam and can also be recycled. Thus, step g) comprises using the at least partially dehydrated molten salt obtained in step f) in step a) or b), and step h) comprises using the steam obtained in step f) in the method, preferably for purging oxygen from the reactor in step a) and / or for hydrating the molten salt in step d).

[0049]

[0051] In the method according to the invention, the hydratable molten salt is a hydratable metal halide salt, the metal being preferably zinc, aluminum, antimony, manganese, calcium, iron, or magnesium or a combination thereof, preferably ZnCl 2 , FeCl 3 , MgCl 2 , MnCl 2 , CaCl 2 or their bromine analogues or blends thereof. All of these compounds are (re)hydratable, and the number of hydrated water molecules in the structure (with the formula metal halide·nH 2O) can be changed. In terms of catalytic properties, the carbonization process uses ZnCl 2 , FeCl 3 , and MnCl 2 AlCl is preferred. 3 is possible, but less suitable since it already forms a gas at temperatures below 500° C. Most preferably, the hydratable molten salt is at least 70 wt.%, more preferably at least 80 wt.%, even more preferably at least 90 wt.%, and most preferably at least 95 wt.% ZnCl 2 and the remainder of the hydratable molten salt preferably comprises one or more other metal halide salts, preferably MgCl 2 , MnCl 2 , AlCl 3 , SbCl 3 , or FeCl 3 It is.

[0050]

[0052] ZnCl 2 ZnCl has a very low vapor pressure and is therefore a very suitable medium for carbonization at high temperatures. The fact that the pressure hardly increases when the temperature is increased is due to the 2 This is a particular advantage of the method using AlCl. The pressure is much lower and therefore the investment in equipment is smaller. This is in contrast to other molten salts, e.g. AlCl, which have a much higher vapor pressure. 3 Therefore, the pressure is less critical and for reasons of convenience, atmospheric or ambient pressure is preferred during the conversion step b). Higher pressures may be used but are preferably less than 10 bar.

[0051]

[0053] In the process according to the invention, the molten salt in step b) preferably comprises less than 20 wt.%, preferably less than 10 wt.%, more preferably less than 5 wt.%, even more preferably less than 3 wt.%, most preferably less than 1 wt.% of water of hydration based on the total weight of the molten salt and water, a low water content being preferred for example to increase the carbonization conversion power required to carbonize the polymer, whereas a high water content is preferred on the other hand with respect to less energy consumption, in particular since less water needs to be removed in step f). The rehydrated molten salt formed in step e) preferably comprises 10-60 wt.%, more preferably 15-50 wt.%, even more preferably 15-35 wt.% of water, the wt.% being based on the total weight of the molten salt, preferably the molten salt is ZnCl 2 The rehydrated molten salt contains at least 10 wt %, more preferably at least 20 wt %, even more preferably at least 25 wt % or 30 wt % more water (wt % is based on the total weight of the molten salt and water) than the dehydrated molten salt of step b) in order to change the solvent quality of the molten salt.

[0052]

[0054] In the method according to the invention, a solid carbon source or its precursor is preferably added in steps a), b) and / or d) as a seed to promote the conversion and / or separation of the carbon phase from the molten salt phase. It is believed that the solid carbon may catalyze the conversion reaction and nucleate the formation and growth of the carbon phase. Examples of solid carbon sources are charcoal, carbon black, carbon fibers, carbon nanofibers, etc. The solid source precursor is a compound that is directly converted in the molten salt to a solid carbon source, e.g. cellulose or lignin.

[0053]

[0055] In a useful embodiment, the converted gas recovered in step c) is further separated into water and dry converted gas, which is 2 , and minimal amounts of C1-C4, CO, and CO 2 This may include generation. The exact generation figure depends on the type of feedstock. 2And / or if pure carbon production is optimized, the cellulose is removed from the TPW beforehand. 2 Sulfur can be captured to avoid the formation of S. The water separated in step d) may be used in a hydration step, AMS converted to HMS or used as steam to purge oxygen from the reactor.

[0054]

[0056] In the process according to the invention, the molten salt further preferably comprises one or more dehydrogenation catalyst metals in catalytic amounts different from the metals in the molten salt, preferably selected from the group of Ni, Fe, Zn or Cu, preferably added in the form of a metal-organic complex, such as a metal alkyl, metal oxide or metal-chloride complex, in an amount of said metal preferably less than 10 mol %, preferably less than 5 mol % or even less than 3 mol % relative to the moles of metal in the molten salt, in order to increase the hydrogen yield in the process, the one or more dehydrogenation catalysts being preferably FeCl 3 , NiCl 2 , CuCl 2 , Fe 2 O 3 The dehydrogenation catalyst is selected from the group consisting of ZnCl, NiO, and CuO, and one or more dehydrogenation catalyst metals are optionally supported on a solid carbon source or a precursor thereof. The use of dehydrogenation catalysts is particularly preferred as it allows for the use of relatively low conversion temperatures. Most preferred are ZnCl, which contains Ni or Fe metal ions as the dehydrogenation catalyst metal. 2 It is particularly preferred to use Fe as the active metal which allows for magnetic separation of the active metal catalyst from the carbon source.

[0055]

[0057] Optionally, the one or more dehydrogenation catalytic metals are supported on a solid carbon source or a precursor thereof. The solid carbon source or a precursor thereof for use as a seed or as a support for the one or more dehydrogenation catalytic metals during the reaction and / or separation steps is the same or a different compound selected from carbon fibers, lignin, cellulosic fibers, carbon nanofibers, or carbon nanotubes.

[0056]

[0058] Alternatively, one or more dehydrogenation catalytic metals may be added to the carbon-containing material feed prior to contact with the hydratable molten salt in the reactor.

[0057]

[0059] In the case where the feed contains significant amounts of heteroatoms, such as N, O, S, P, or halogens, the process may further comprise the steps of: converting the heteroatom-containing impurities formed during the conversion step b); in particular one or more of the halogens, CO 2 , S.O. x , NO x Preferably, one or more reactants are added to the molten salt to convert the impurities. Preferably, the reactants react with the impurities to form a precipitate, which can then be separated. Preferably, the reactants are metal compounds, more preferably metal oxides or metal hydroxides, even more preferably zinc oxide, magnesium oxide, iron oxide, or nickel oxide, and are free of halogens, CO 2 , S.O. x , or NO x to form one or more metal halides, carbonates, sulfates, or nitrates. If the heteroatom is a halogen, e.g., from a PVC polymer, the halogen gas formed during the conversion (e.g., Cl 2 ) is converted to a metal halide along with the metal oxide, which can be separated or becomes part of the molten salt used in the process and does not need to be separated.

[0058]

[0060] For example, oxygen-containing compounds decompose to CO 2 , which can be captured by metal oxides to produce metal carbonates. PVC or halogen-based flame retardants in the TPW produce halogens when in contact with the molten salt. These halogens can react with the metal oxides to reduce toxic halogen emissions. In a preferred embodiment, the reactant is zinc oxide, which reacts with chlorine formed in the decomposition of PVC to produce ZnCl. 2which is the preferred molten salt and can then be used in the process. If the contaminant heteroatom contains Br or F, the reactant zinc oxide can be reacted to produce the reaction product ZnBr 2 or ZnF 2 and ZnCl, respectively. Bromide can be removed by adding MgO. In the most preferred embodiment, the molten salt used in the process is zinc chloride, and in the process of converting halogen-containing TPW, particularly halogen-containing TP, zinc oxide is added as a reactant to form zinc chloride. In the case of sulfur-containing mixtures, it decomposes to SO x Zn halides can be converted to Zn(OH) by contacting with NaOH to give Zn(OH) 2 (ZnCl 2 +NaOH = Zn(OH) 2 +NaCl), which can be precipitated and separated. When the resulting zinc hydroxide is heated, it causes the formation of zinc oxide, which can be used as a reactant in the process.

[0059]

[0061] In an alternative embodiment, when the waste feed contains biological waste material containing carbohydrates, such as cellulose, it is advantageous to separate and remove the carbohydrates first. Firstly, this is because it produces another valuable product, but also because carbohydrates are less favored in carbonization processes because they produce water. Thus, in the method according to the invention, the at least partially rehydrated molten salt produced in step d) and separated in step e) is used in a separate step e.1) for the separation of bio-organic waste, preferably bio-organic waste containing cellulose, hemicellulose and / or lignin, at a temperature below 300°C, preferably below 250°C, preferably before being dehydrated in step f). The at least partially rehydrated molten salt produced in step d) and separated in step e) can be used to carbonize the bio-organic waste separately, since it can be carbonized more easily at low temperatures and high water content.

[0060]

[0062] In the process according to the invention, the NVC phase separated in step e) is washed with water at a temperature below 100° C. to dissolve and remove the molten salt residues, the wash water being preferably recycled to step d).

[0061]

[0063] The energy required in the process for heating and conversion is preferably generated by combustion of the hydrogen produced in the process. The advantage of this process is that the energy obtained by conversion of the TPW is generally higher than the energy required for the process itself.

[0062]

[0064] It is a particular advantage of the method that the solid carbon phase separated from the molten salt in step e) can produce or can be used to produce valuable high quality carbon materials. Preferably, the carbon phase can produce or can be used to produce activated carbon (i.e. adsorbents), soil enhancement compounds, electronic materials, carbon fibers, carbon nanofibers or carbon nanofiber precursors, graphene or graphene precursors (i.e. materials). The formed product after isolation can also be used as a seed in the same method.

[0063]

[0065] The present invention relates to a carbon-containing feed, preferably a waste feed comprising a synthetic polymer, preferably a thermoplastic polymer-containing waste (TPW) and / or a hydrocarbon waste (HCW), wherein the carbon-containing feed, preferably the TPW, 1) providing a carbon-containing feed and a hydratable molten salt and at least partially converting the carbon-containing feed in the molten salt in a carbonization reactor to form a converted gas and carbon; 2) passing the converted gas from the carbonization reactor to a liquefaction device to condense the water vapor and separate the dry converted gas, and transferring a portion of the molten salt containing carbon to a separation reactor; 3) adding water or water vapor to the carbon-containing molten salt in a separation reactor to cool and rehydrate the molten salt to form a phase-separated non-volatile carbon phase and an at least partially rehydrated molten salt phase; 4) separating and transferring the at least partially rehydrated molten salt phase from the separation reactor; 5) optionally using the at least partially rehydrated molten salt phase from the separation reactor for separation or carbonization of bio-organic waste and separating the at least partially rehydrated molten salt after use in this process; 6) transferring the at least partially rehydrated molten salt to a heating reactor, heating the at least partially rehydrated molten salt phase to dehydrate it to an at least partially dehydrated molten salt and water vapor, and recycling the at least partially dehydrated molten salt back to the carbonization reactor or transferring the at least partially rehydrated molten salt directly to the carbonization reactor, heating the at least partially rehydrated molten salt phase in the carbonization reactor to dehydrate it to an at least partially dehydrated molten salt and water vapor; 7) optionally removing impurities from the at least partially dehydrated or at least partially rehydrated molten salt before recycling it back to the carbonization reactor; 8) continuously or semi-continuously removing the non-volatile carbon phase from the separation reactor, optionally followed by washing the non-volatile carbon phase with water to remove molten salt residues, optionally followed by recycling a portion of the non-volatile carbon phase or a portion of the solid carbon isolated from the separated non-volatile carbon phase back into the carbonization reactor as seeds to promote conversion and / or separation of the non-volatile carbon; 9) Optionally, the inorganic matter is converted in a continuous process comprising separating the inorganic matter from a mixture of carbon-containing feed in molten salt by density difference prior to carbonization.

[0064] Preferably, at least a part of the conversion in step b) is carried out in a mixer exhibiting very high shear rates, such as a static mixer.

[0065] Description of exemplary embodiments

[0066] FIG. 1 is a schematic diagram of an embodiment of the process of the present invention, in which a thermoplastic waste feed TPW is fed to a preheater PH1, oxygen is purged with water vapor ST, the temperature is raised to a temperature Tp that melts the TP in the TPW feed and forms a polymer melt Pm, and AMS is heated under a water vapor atmosphere ([H 2 O]) is preheated in preheater PH2. Alternatively, TPW and AMS can be mixed and heated in a different order or fed directly to reactor R1.

[0066]

[0067] The polymer melt Pm and the preheated AMS are mixed and fed into the first reactor R1 via a feeding unit F (e.g. an extruder or an in-line mixer), where TP is converted into a conversion gas G1, which mainly contains hydrogen and water vapor and is released at the top. The reaction mixture containing AMS and non-volatile conversion products is transferred to a separation reactor R2.

[0067]

[0068] In reactor R2, water or steam is added to the reaction mixture to cool the reaction mixture and convert the AMS to hydrated molten salt (HMS) and form phase separated NVC and HMS phases. Preferably, recycled steam or condensed steam is used from gas separator CR, and the steam in gas G1 is condensed to separate the water and produce water-free converted gas G2.

[0068]

[0069] The HMS phase is separated and transferred from the second reactor R2 for recycling. Optionally, at least a portion of the HMS phase is transferred from the second reactor R2 to a third reactor R3 for separation or carbonization of bio-organic waste (BOC), e.g. cellulose-containing waste, as known in the art. Preferably, in this reaction step, cellulose can be dissolved in HMS, a solution of cellulose in HMS is separated, and then cellulose is precipitated and separated, e.g. by adding an anti-solvent. Alternatively, BOC can be carbonized in reactor R3. Also, after this step, the HMS phase is separated for recycling after use. In this way, the waste stream containing TP and BOC is efficiently converted into useful products after separation of TP and BOC.

[0069]

[0070] The NVC phase from the second reactor R2 can be separated continuously or semi-continuously, optionally followed by washing the NVC phase with water to remove molten salt residues, and optionally followed by recycling a portion of the NVC phase, or a portion of the solid carbon isolated from the separated NVC phase, back to the first reactor as seeds to promote conversion and / or separation of NVC (not shown in FIG. 1 ).

[0070]

[0071] The HMS phase from R2 and / or R3 is transferred to the fourth reactor R4 and converted back to AMS and water vapor by heating (T) the recycled spent HMS phase, after which the AMS is recycled back to the first reactor R1 either directly to R1 or indirectly via preheater PH2 and / or feed unit F. The water vapor generated in R4 can be used to purge PH1, PH2, or other reactors, or is recycled to the CR in gas stream G1.

[0071]

[0072] Optionally, in the fifth reactor R5, a base B can be added to (a part of) the recycled HMS phase coming from reactors R2 and / or R3 and / or to (a part of) the AMS coming from reactor R4 in order to convert the metals of the molten metal salts to metal oxides, which are separated and transferred to R1. The metal oxides RE act as reactants RE to capture the heteroatom-containing impurities formed in reactor R1. In a preferred embodiment in which the molten salt is zinc chloride, zinc oxide is formed as RE in R5. Optionally (not shown in FIG. 1), instead of or in addition to this optional step in R5, another reactant RE can be added separately to reactor R1 to capture the heteroatom-containing impurities formed in the first reactor R1.

[0072]

[0073] Figure 2 shows that the hydrocarbon feed is primarily composed of carbon [C] and H 2 , C.H. 4 , CO 2 FIG. 1 is a schematic diagram of an embodiment of a simplified practical embodiment of the process of the present invention, in which a converted gas containing 1. Carbon-containing feed mixed with molten salt hydrate 2. Removal of inorganic matter by optional pretreatment 3. Carbonization reactor 4. Molten salt-containing carbon phase 5.Regenerated molten salt 6. Carbon Separation Compartment 7. Gases produced by carbonization (including water vapor) 8. Water and dry carbon gas; mainly H 2 , C.H. 4 , CO 2 Liquefaction equipment to separate 9. Water collector 10. Recycle of water (or steam) to the reactor section 11. Pressure control, as shown.

[0073]

[0074] FIG. 3 is a schematic diagram of the same embodiment of the process of FIG. 2 with the heat flows indicated: Q1 = reactor heating, Q2 = feed heating, Q3 = gas cooling and water condensation, and Q4 = cooling of the effluent from the carbonization reactor.

[0074]

[0075] The invention is further illustrated by the experiments described below.

[0075] Experiment 1

[0076] Lignin (0.5 gr) 70 wt% ZnCl 2 (ZnCl 2 and total weight of water of hydration) 2 The mixture was mixed with 16 gr of hydrate and placed in a Hastelloy tubular reactor (16 ml volume). The mixture was stirred continuously during the experiment. The air in the reactor was replaced with nitrogen by three alternating cycles of applying a vacuum and pressurizing with 8 bar of nitrogen. The reactor was closed at atmospheric pressure and placed in a heated oven. The temperature of the reactor was increased to 290°C and the reactor was maintained at this temperature for 90 minutes. The reactor was removed from the oven and cooled to room temperature. The gas phase was removed from the reactor by releasing the pressure built up by the water vapor and analyzed using gas chromatography and mass spectrometry. The carbon phase was separated by adding water and ZnCl 2 The results are shown in Table 1. 2 and carbon yields are in weight percent based on the feed weight. 0% liquid hydrocarbons means that no condensed liquid hydrocarbons were observed after cooling to room temperature of 22°C.

[0076] Experiments 2-8 Experiments 2-8 were carried out in the same manner as described in experiment 1, except that the carbon-containing material, carbonization time and temperature, and molten salt water content were varied as described in Table 1. Anhydrous ZnCl 2 The molten salt contained no water.

[0077] [Table 1]

[0078] Experiments have shown that very high yields of carbon can be obtained at very low temperatures for different types of feed. Experiments have shown that it is easier to convert bio-based materials (lignin, cellulose, and sugars) than polymers, but the latter were well converted at somewhat higher temperatures. At temperatures above 290°C, the molten salts dehydrated, and at temperatures above 320°C, the molten salts were anhydrous. Carbohydrates produce mainly carbon and water, so H 2 The yield is low. Good H from the carbonization of polyethylene 2 The yield was obtained. The experiment shows the feasibility of the present invention.

[0079]

[0078] In addition to those described above, further modifications may be made to the structures and techniques described herein without departing from the spirit and scope of the present invention. Thus, although specific embodiments have been described, these are merely examples and are not intended to limit the scope of the present invention.

Claims

1. 1. A method for converting a carbon-containing material, comprising the steps of: a. contacting and mixing the carbon-containing material with a hydratable molten salt; b. subjecting the carbon-containing material in the molten salt to carbonization conditions i. at a temperature T1 between 200° C. and 500° C., preferably between 200° C. and 400° C., more preferably between 200° C. and 350° C.; and ii. at a pressure of preferably less than 50 bar, more preferably less than 15 bar, even more preferably less than 10 bar, and most preferably less than 1 bar; iii. There is no oxygen; iv. the hydratable molten salt is at least partially dehydrated; v. The presence of water vapor as an inert gas; vi. forming a reaction mixture comprising the converted gas and non-volatile conversion products comprising carbon in said molten salt; converting in a reactor under c) recovering the converted gas from an outlet of said reactor, optionally assisted by purging with water vapor, optionally cooling said converted gas to condense said water vapor, and recovering a dry converted gas; d. adding water or steam to the reaction mixture to cool the reaction mixture and rehydrate the molten salt, thereby causing phase separation to form a non-volatile carbon phase and an at least partially rehydrated molten salt phase; e. separating the non-volatile carbon phase from the at least partially rehydrated molten salt phase; f. heating the resulting partially rehydrated molten salt phase to form at least partially dehydrated molten salt and water vapor, preferably in step a), in step b), or in a separate step; g. Using the at least partially dehydrated molten salt phase in step a) or b). h. Preferably, the method further comprises using the water vapor obtained in step f) preferably for purging oxygen from the reactor and the carbon-containing material in step a) and / or for hydrating the molten salt in step d); i. Optionally separating inorganic matter in a separation step, where inorganic solids are separated from said molten salt by density difference, preferably after step a) and before step b). The method includes:

2. 2. The method of claim 1, wherein the carbon-containing material is a waste material containing hydrocarbons, preferably waste oil or refinery residues, and / or a synthetic polymer, preferably a thermoplastic polymer.

3. 3. The method of claim 1 or 2, wherein the carbon-containing material is a thermoplastic waste (TPW) comprising at least 50 wt.%, more preferably at least 60 wt.%, 70 wt.%, 80 wt.%, or even more preferably at least 90 wt.% thermoplastic polymer (TP) and preferably less than 40 wt.%, more preferably less than 30 wt.%, even more preferably less than 20 wt.% thermosetting polymer, preferably also less than 20 wt.% other waste feed components, the thermoplastic polymer waste preferably comprising one or more thermoplastic polymers selected from the group consisting of polypropylene, polyethylene, polyester, polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, or mixtures, copolymers, blends, or composites thereof, preferably comprising a thermoplastic polymer not containing heteroatoms O, N, or halogens, most preferably a polyolefin.

4. The hydratable molten salt is a hydratable metal halide salt, the metal being preferably zinc, aluminum, antimony, manganese, calcium, iron, or magnesium or a combination thereof, preferably ZnCl ２ , FeCl ３ , MgCl ２ , MnCl ２ , CaCl ２ or their bromine analogs or blends thereof, and most preferably, the molten salt comprises at least 70 wt. %, more preferably at least 80 wt. %, even more preferably at least 90 wt. %, and most preferably at least 95 wt. % ZnCl ２ and the remainder of the molten salt preferably comprises one or more other metal halide salts, preferably AlCl ３ , MnCl ２ , SbCl ３ , or FeCl ３ The method according to any one of claims 1 to 3,

5. - in step b), the molten salt comprises less than 20 wt. %, preferably less than 10 wt. %, more preferably less than 5 wt. %, even more preferably less than 1 wt. % of water of hydration relative to the total weight of the molten salt and water, in step e), the rehydrated molten salt contains 10 to 60 wt. %, preferably 15 to 50 wt. %, more preferably 15 to 35 wt. % water, A method according to any one of claims 1 to 4, wherein the rehydrated molten salt phase contains at least 10 wt. %, preferably at least 20 wt. %, more preferably at least 30 wt. % more water than the dehydrated molten salt phase.

6. The cooling and separation steps d) and e) comprise one or more cooling and separation steps, preferably - cooling said reaction mixture to a temperature TI below 200°C, preferably below 150°C, and allowing it to hydrate, or cooling at least a portion of said reaction mixture to a temperature Th above 200° C., preferably above 250° C. or even above 300° C., optionally subjecting it to pressure, this pressure preferably being applied with water vapor, or The method according to any one of claims 1 to 5, wherein two or more subsequent cooling and separation steps are applied at different temperatures, preferably initially step iii) is applied at a high temperature Th and then step ii) is applied at a low temperature TI, obtaining two or more different NVC fractions differing in composition.

7. 7. The method according to any of the claims 1 to 6, wherein the at least partially rehydrated molten salt phase obtained in step e) is heated in step f) to a temperature above 250°C, preferably above 300°C in order to dehydrate the molten salt, or the at least partially rehydrated molten salt in step f) is dehydrated by applying heating and vacuum at a pressure below 100 Pa, more preferably below 0.1 Pa, even more preferably below 0.0001 Pa, preferably at a temperature below 175°C, more preferably below 150°C and above 100°C, preferably above 120°C, optionally adding a metal oxide before or during heating, the metal being preferably the same as that of the molten salt.

8. 8. The method according to any one of claims 1 to 7, wherein the at least partially rehydrated molten salt phase obtained in step e) is recycled to the reactor of step b) and the heating of the rehydrated molten salt in step f) is carried out in a carbonization reactor to form a dehydrated molten salt.

9. 9. The method according to any one of claims 1 to 8, wherein a solid carbon source or a precursor thereof is preferably added in steps a), b) and / or d) as a seed to promote the conversion and / or separation of a carbon phase from the molten salt phase.

10. 10. The process according to any one of claims 1 to 9, wherein the converted gas recovered in step c) is cooled to condense the water vapor to recover water and a dry converted gas, the dry converted gas comprising less than 10 wt. %, preferably less than 5 wt. %, even more preferably less than 3 wt. % of hydrocarbons having 2 or more carbon atoms.

11. The molten salt of step b) further comprises one or more dehydrogenation catalyst metals in catalytic amounts different from the metals in the molten salt, preferably selected from the group of Ni, Fe, Zn or Cu, preferably added in the form of a metal-organic complex, such as a metal alkyl, metal oxide or metal-chloride complex, in order to increase the hydrogen yield in the process, preferably in an amount of less than 10 mol %, preferably less than 5 mol % or even less than 3 mol % of said metal relative to the moles of metal in the molten salt, the one or more dehydrogenation catalysts being preferably FeCl ３ , NiCl ２ , CuCl ２ , Fe ２ O ３ 11. The method of claim 1, wherein the one or more dehydrogenation catalytic metals are selected from the group of: MnO, NiO, and CuO, and the one or more dehydrogenation catalytic metals are optionally supported on a solid carbon source or a precursor thereof.

12. In step a) or b), one or more reactants are added to the molten salt to react with heteroatom-containing impurities present or formed during carbonization conversion step b), preferably the one or more impurities are halogens, CO ２ 12. The method according to any one of claims 1 to 11, wherein the reactants are selected from the group consisting of: , SOx and NOx, and the reactants form a precipitate which can be separated, which reactants are preferably metal compounds, more preferably metal oxides or metal hydroxides, even more preferably zinc oxide, magnesium oxide, iron oxide or nickel oxide, and form one or more metal halides, metal carbonates, metal sulfates or metal nitrates, or preferably the heteroatom is a halogen and converts with a metal oxide, preferably zinc oxide, to a metal halide, preferably zinc halide, which is part of the molten salt used in the method and does not need to be separated.

13. 13. The method according to any one of claims 1 to 12, wherein the at least partially rehydrated molten salt phase obtained in step e) is used in a further step e.1) for separation or carbonization of bio-organic waste, preferably bio-organic waste containing cellulose, hemicellulose and / or lignin, at a temperature below 300°C, preferably below 250°C, before being dehydrated and used in step a) or b).

14. 14. The method according to any one of claims 1 to 13, wherein the non-volatile carbon phase obtained in step e) is washed with water at a temperature below 100°C to dissolve and remove the residues of the molten salt, preferably recycling the wash water to step d).

15. The carbon-containing feed, preferably TPW, 1) providing a carbon-containing feed and a hydratable molten salt and at least partially converting the carbon-containing feed in the molten salt in a carbonization reactor to form a converted gas and carbon; 2) passing the converted gas from the carbonization reactor to a liquefaction system to condense water vapor and separate a dry converted gas and transfer a portion of the molten salt containing the carbon to a separation reactor; 3) adding water or steam to the carbon-containing molten salt in the separation reactor to cool and rehydrate the molten salt to form a phase-separated non-volatile carbon phase and an at least partially rehydrated molten salt phase; 4) separating and transferring the at least partially rehydrated molten salt phase from the separation reactor; 5) optionally using the at least partially rehydrated molten salt phase from the separation reactor for separation or carbonization of bio-organic waste, and separating the at least partially rehydrated molten salt after use in this process; 6) transferring the at least partially rehydrated molten salt to a heating reactor and heating the at least partially rehydrated molten salt phase to dehydrate it to an at least partially dehydrated molten salt and water vapor and recycling the at least partially dehydrated molten salt back to the carbonization reactor or transferring the at least partially rehydrated molten salt directly to a carbonization reactor and heating the at least partially rehydrated molten salt phase in the carbonization reactor to dehydrate it to an at least partially dehydrated molten salt and water vapor; 7) Optionally removing impurities from the at least partially dehydrated molten salt or the at least partially rehydrated molten salt before recycling it back to the carbonization reactor. 8) continuously or semi-continuously removing the non-volatile carbon phase from the separation reactor, optionally followed by washing the non-volatile carbon phase with water to remove residues of the molten salt, and optionally followed by recycling a portion of the non-volatile carbon phase or a portion of solid carbon isolated from the separated non-volatile carbon phase back into the carbonization reactor as seeds to promote the conversion and / or separation of the non-volatile carbon; 9) Optionally, inorganic matter is separated from the mixture of carbon-containing feed in the molten salt by density difference prior to carbonization; The method according to any one of claims 1 to 14, wherein the conversion is carried out in a continuous process comprising in succession

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