Process for the production of synthesis gas from carbonaceous waste material

Abstract

A process for the production of syngas from carbonaceous waste material and CO2, comprising the following phases: phase a) comprising reaction [R1], in which carbon dioxide is reacted with carbonaceous material to obtain carbon monoxide according to the following reaction scheme: [R1] CO2 + C = 2CO; phase b) to obtain syngas by producing H2 and adding it to the carbon monoxide obtained in phase a), wherein phase b) comprises at least one of the following phases: b1) to obtain carbon dioxide and hydrogen by reacting the carbon monoxide from the previous phase with water vapour according to the following reaction scheme: [R2] CO + H2O = CO2 + H2; b2) to produce hydrogen by means of electrolysis of water, which is added to the carbon monoxide from phase a). The invention also relates to units for carrying out phases a) and b1) and to the relative plants comprising the aforementioned units.

Description

Technical Field

[0001] This invention relates to a method for producing syngas from CO2 and waste carbonaceous materials. Background Technology

[0002] In industrial processes, CO2 reuse typically involves the use of large quantities of hydrogen or hydrogen-rich molecules in reactions such as full hydrogenation, such as the Sabatier reaction or methanation (Che, M., 1912 Nobel Prize in Chemistry, Sabatier: Organic Chemistry or Catalysis, Catalysis Today, 218–219, 162–171, 2013) to obtain methane; dry reforming reactions (Vita et al., Methanolsynthesis from biogas: A thermodynamic analysis, Renewable Energy, 118, 673–684, 2018) to obtain intermediate syngas for the synthesis of high-value-added chemicals such as methanol and dimethyl ether; or reactions with hydrogen sulfide (Manenti, CO2 as feedstock: A new pathway to syngas, Computer Aided Chemical Engineering, 37, 1049–1054, 2015).

[0003] As is well known, one of the issues concerning the circular economy involves the reuse of carbon-containing materials, such as those contained in rubber dust, coke, residual biomass, and carbon-containing materials obtained from processing waste. Summary of the Invention

[0004] The applicant has now discovered a method for producing syngas that uses CO2 as a starting material, does not require large amounts of hydrogen, and uses waste carbonaceous materials without relying on large amounts of hydrogen.

[0005] The method for forming the subject matter of this invention includes the following stages:

[0006] - Stage a), comprising reaction [R1], wherein a carbon-containing material is reacted with carbon dioxide to produce carbon monoxide according to the following reaction scheme:

[0007] [R1] CO2 + C = 2CO;

[0008] -In stage b), hydrogen is produced and added to the carbon monoxide obtained in stage a) to obtain syngas.

[0009] The characteristic is that stage b) includes at least one of the following stages:

[0010] b1) According to the following reaction scheme, carbon monoxide from the previous stage reacts with water vapor to obtain carbon dioxide and hydrogen:

[0011] [R2] CO + H2O = CO2 + H2

[0012] b2) Hydrogen is produced by the electrolysis of water and added to the carbon monoxide from stage a).

[0013] A further object of the present invention is the unit for stages a) and b1), and the related device comprising said unit. Attached Figure Description

[0014] Figure 1 A preferred schematic configuration of the device 1 according to the invention is shown for performing stages a) and b1) of the method of the invention in both the presence and absence of oxygen when the carbon-containing material is in a solid state.

[0015] Figure 2B This shows that when stage a) is carried out in the presence of oxygen... Figure 1 The process takes place in Unit 1.1, where the lower section A and the upper section B are divided into different regions based on what happens inside them.

[0016] Figure 2A Then it shows, as Figure 2B The graph shown is a curve of the height of the gas and carbonaceous solid material in container 1.1 as a function of temperature during the process.

[0017] Figure 3 A block diagram of a preferred embodiment of the method of the present invention is shown.

[0018] Figure 4B It shows when in Figure 1 When the method of the present invention is carried out in unit 1.1, wherein stage a) is carried out in the absence of oxygen, the lower section A and the upper section B are divided into different regions according to what happens inside them.

[0019] Figure 4A It shows that in such Figure 4B The graph shown is a function of temperature for the height of the gas and carbonaceous solid material in unit 1.1 during the process.

[0020] Figure 5 A block diagram of a preferred embodiment of the method of the present invention is shown.

[0021] Figure 6 A block diagram of the method of the present invention is shown.

[0022] Figure 7 A block diagram of a preferred embodiment of the method of the present invention is shown.

[0023] Figure 8 A block diagram of a preferred embodiment of the method of the present invention is shown.

[0024] Figure 9 A block diagram of one embodiment of the method of the present invention is shown.

[0025] Figure 10A and Figure 10B Two block diagrams are shown for two preferred embodiments of the method of the present invention. Detailed Implementation

[0026] For the purposes of this invention, the term "comprising" does not exclude the possibility that the methods and apparatus according to the invention may each comprise multiple stages or multiple components not listed after the definition.

[0027] The terms “consist” or “composed of” exclude this possibility.

[0028] For the purposes of this invention, residues or waste carbon-containing materials refer to waste materials containing a large amount of elemental or bound carbon (preferably >30%, more preferably >50%, and even more preferably >80%), such as rubber dust, coke, residual biomass, and organic material processing waste.

[0029] Elemental carbon refers to carbon that is covalently bonded to heteroatoms other than carbon (such as H, O, P, S, N, etc.).

[0030] Non-volatile carbon-containing materials refer to materials that do not react with CO2 in [R1], contain ash as the main component and have an elemental carbon content of less than 30%, preferably less than 20%, and even more preferably less than 10%.

[0031] Biot number (Bi) refers to:

[0032]

[0033] ·h is the coefficient for heat exchange with the outside (W / m) 2 / K)

[0034] • L is the characteristic length, which is usually chosen to be equal to the equivalent diameter (m) of the solid;

[0035] λ is the thermal conductivity of the solid.

[0036] Equivalent diameter refers to the diameter of an imaginary spherical particle that has the same geometric, optical, electrical, or aerodynamic behavior as a real non-spherical particle.

[0037] For the purposes of this invention, in synthesis gas, S and SN refer to:

[0038] S = H2 / CO

[0039] SN = (H2 – CO2) / (CO + CO2)

[0040] The reaction [R1] is better known as the reverse Boudouard reaction.

[0041] The reaction [R2] is better known as the Fontana reaction or the water gas shift reaction.

[0042] When the method of the present invention provides a stage b) including stage b1), the method of the present invention is also referred to in the present invention by the acronym RBF (Reverse Boudouard Fontana).

[0043] The electrolytic cell used in stage b2) is preferably a solid oxide electrolytic cell, also referred to by the acronym SOEC (Solid Oxide Electrolytic Cell). However, other electrolytic cells, such as polymer electrolytic cells or cryogenic electrolytic cells, may also be used.

[0044] The definition of self-heating technology refers to a process that, apart from the start-up phase, is self-sustaining in terms of energy.

[0045] This occurs when, in the method of the present invention, stage a) is carried out in the presence of oxygen or an oxygen-containing mixture.

[0046] The temperature at which the reaction [R1] is carried out is at least 600°C, preferably at least 700°C, more preferably at least 800°C, and under optimal conditions at least 900°C.

[0047] The temperature of reaction [R2] is equal to or lower than the temperature of [R1], preferably not lower than 620°C, and more preferably not lower than 650°C.

[0048] The temperature of stage b1) is 100°C to 900°C [R1], preferably 500°C to 900°C, more preferably 700°C to 900°C, and optimally at 828°C (Hillestad et al., 2018, Improving carbon efficiency and profitability of the biomassto liquid process with hydrogen from renewable power, Fuel, 234, 1431-1451).

[0049] The method of the present invention is preferably carried out at a pressure of 1 to 200 bar, more preferably 1 to 100 bar, and more preferably 20 to 100 bar, and uses steam or water under similar pressure conditions.

[0050] In the method according to the invention, stage a) can be carried out with or without oxygen.

[0051] When stage a) is carried out in the presence of oxygen in the method according to the invention, the entire method is self-heating because, especially in the RBF process, it utilizes the enthalpy of the effluent leaving reaction [R1] to ensure the self-heating of the electrolyzer and reaction R2, with a significant energy advantage.

[0052] Sometimes, in the method according to the invention, when stage a) is carried out in the presence of oxygen and operated at a temperature above 700°C, preferably above 800°C, it is not necessary to completely add the required amount of CO2, because in stage a) CO2 is formed by oxidation according to the following reaction:

[0053] [R4] C + O2 = CO2

[0054] This process can be carried out in an endothermic mode, which occurs in stage a) of the method of the present invention when oxygen is absent, in which case an external CO2 source is always used, for example, by electricity, solar concentrating, or simply by utilizing the high temperature at which it leaves the kiln or furnace.

[0055] When stage b) in the method according to the invention includes or consists of stage b1), it is preferably shown as an object of the invention and its preferred embodiment is illustrated in Figure 1 It is carried out in another device.

[0056] Specifically, device 1 includes a unit consisting of a generally cylindrical sealed container 1.1, which is formed by an upper section B and a lower section A separated from each other by a dust collector 1.3, wherein:

[0057] The upper section B of stage b1) of the method of the present invention includes:

[0058] · Fixed catalyst bed 1.4,

[0059] • Gas outlet 1.10 is configured on the side above the catalyst bed 1.2.

[0060] • A water inlet 1.11 is configured on the side and a water distributor 1.12 is configured inside the upper section B, parallel to the dust collector 1.3 and above the dust collector 1.3. At the top of the upper section B, the inlet 1.13 is used to load fresh catalyst, and at the side, an outlet 1.14 is configured on the side in the upper section B to allow the removal of waste catalyst.

[0061] The lower segment A, in which stage a) of the method according to the invention occurs, includes:

[0062] • Device 1.7 for introducing fresh carbonaceous residue material,

[0063] • A bed of non-volatile carbonaceous residue material, 1.5m thick;

[0064] • A grid or perforated plate 1.6 for separating the non-volatile carbonaceous residue material and allowing it to be removed by means of a hopper 1.16 disposed below the grid or perforated plate and connected to an outlet 1.15 disposed at the bottom of the lower section A.

[0065] • An inlet 1.17 for CO2 gas and possibly O2 gas is located below the grille 1.6.

[0066] The device 1 according to the invention further includes:

[0067] - A fan 8 is directly connected to a heating unit 9, which in turn is directly connected to an inlet 1.17 for the reaction gases (CO2 and possibly oxygen) located on the bottom side of the lower section A of the container 1.1.

[0068] exist Figure 1 In the preferred embodiment shown, the fresh carbonaceous material used as the reactant is a solid, and therefore the device for loading it into the lower section of the container is a screw conveyor 1.7, preferably facing upwards, to avoid premature degradation caused by hot flue gas from below.

[0069] On the other hand, when the fresh carbonaceous residue material has a paste-like or fluid consistency, it is loaded into the container using a slurry pump and loading line, and distributed inside the lower section A using a distributor or sprayer.

[0070] When the method is carried out in device 1, stage a) is carried out in the presence of oxygen, in a self-heating mode and using fresh solid carbonaceous material, and the method includes the following operational stages.

[0071] In the lower section A, fresh solid carbonaceous material is fed into the head of the lower section by means of a screw conveyor 1.7 and gradually descends, coming into contact with the hot gas rising through the lower section A under different thermal conditions, exchanging heat and mass, so that in the uppermost part of the lower section, any moisture present in the fresh solid carbonaceous material is finally removed. In the lower part, the dried carbonaceous material is further heated and rapidly encounters increasingly hot gas, where a reaction [R1] occurs. The hot gas containing CO2 causes the carbonaceous material to completely or partially volatilize, converting it completely or partially into CO, and itself into CO. In the last part of the lower section, the non-volatile carbonaceous residue material undergoes thermal reversal towards the gas due to a high Biot number, becoming hotter inside than outside, heating the gas, and depositing on the grid 1.6.

[0072] In section A, carbon dioxide and oxygen are blown into fan 8 and preheated in heating unit 9, which is used only to start the equipment (1). Gases supplied from below through opening (1.17) enter the lower section (A) of container 1.1, rise countercurrently to contact the carbon-containing hot solid material, and are further heated to the temperature required to activate the exothermic oxidation reaction.

[0073] [R3] C + 0.5O2 = CO

[0074] When CO2 is generated in situ in lower section A without being supplied, reaction [R3] combines with the exothermic oxidation reaction:

[0075] [R4] C + O2 = CO2

[0076] The exothermic reaction [R3], which may be associated with reaction [R4], can heat the gas to a temperature higher than that of the solid particles until the oxygen is completely consumed and a sufficiently high temperature is reached, at least 500°C, more preferably at least 600°C, and even more preferably 700°C, to allow the endothermic reaction [R1] to occur, after which the gas slowly begins to cool by transferring heat to the carbon-containing fresh material entering the head of the lower section B.

[0077] The gas exiting from the lower section A passes through the dust collector 1.3 and, once filtered, enters the upper section B, where the reaction [R2] occurs, producing hydrogen and partially reforming carbon monoxide into CO2, such that the effluent exits at a temperature not lower than 620°C, thereby allowing the reaction to shift appropriately to the right or permitting partial reforming of CO2 from CO to produce hydrogen with the same stoichiometry as [R2].

[0078] The catalyst used in section B is selected from conventional types, such as iron, chromium, or other transition metals.

[0079] Figure 2BThis is a schematic representation of the process when stage a) is carried out in the presence of oxygen, and the above method occurs in unit 1.1 of device 1. For this purpose, lower section A and upper section B are divided into different regions based on what happens inside them. Specifically, 1.4 represents the region in lower section A of container 1.1 where carbon dioxide reduction occurs.

[0080] In region 1.4, different areas can be distinguished from the bottom up. The first area cools the solid and releases heat, denoted as solid cooling (SOLID COOLING) and gas preheating (GAS PREHEATING). The area shown above in the diagram represents oxidation, where exothermic oxidation reactions [R3] and [R4] occur. Heat is generated by raising the gas temperature to, for example, the temperature at which the reverse Bouduard reaction is activated in the area above, denoted as [R1]. In the area above the reaction [R1], denoted as solid preheating (SOLID PREHEATING) and gas cooling (GAS COOLING), the gas is cooled by transferring heat and preheating the fresh solid carbonaceous material introduced into the area.

[0081] Figure 2A The height (in meters) of the gas and carbonaceous solid material in container 1.1 as a function of temperature (in °C) is shown in qualitative diagram form when the system is operating using the method described above. Starting from the bottom, it is highlighted how the direct contact between the solid particles and the solid-gas phase contributes to increasing the temperature of the gas introduced from the bottom. Once the appropriate ignition temperature is reached, typically at a distance of one meter from the bottom of the unit, oxygen is activated and begins to oxidize some of the solid and some of the thermally volatile substances, allowing the gas to exceed the temperature of the solid as the unit rises. The peak temperature (hot spot) is obtained from the gas when the oxygen is completely consumed along the rising path of the unit. By further raising the unit from the peak temperature, the gas gradually heats the solid, gradually loses heat and lowers its temperature until it reaches the optimal conditions for moving to the upper region.

[0082] In the new zone, water (by means of an atomizer) or steam can be supplied to correct the temperature if necessary to achieve optimal conditions for the reaction [R2], which occurs under substantially thermal equilibrium or mild exothermic / endothermic conditions depending on the selected temperature. The dashed section represents the temperature of the gas in section B of the container if it comes into contact with a spray of water or steam at a lower temperature than that of the catalytic bed 1.2 (where the Fontana reaction occurs).

[0083] Under preferred conditions, the reaction [R2] is carried out at about 620-650 °C and occurs under weakly exothermic conditions.

[0084] However, in certain implementation modes, only a portion of the airflow from the underlying zone can be supplied to the overlying zone, with the remainder bypassed to the outside, in order to push the reaction [R2] to its maximum potential, up to a low temperature, even equal to 200-250°C. The bypass and exhaust airflow from the unit head can then be mixed externally.

[0085] Phase a) of the method, which is the subject of this invention, involves the use of a carbonaceous residue material with a paste-like consistency in the presence of oxygen, and can be carried out in apparatus 1. In this case, fresh carbonaceous material is fed into a distributor (which sprays it from top to bottom) by means of a slurry pump and a loading line and distributed inside the lower section A. These droplets encounter gases rising through the lower section A under different thermal conditions, exchanging heat and mass, such that in the upper part of the lower section, any moisture present in the fresh carbonaceous solid material is eventually removed. In the lower part, the dried carbonaceous material is further heated and rapidly encounters increasingly hot gases, and reaction R1 occurs in this region, where the hot gas containing CO2 causes the carbonaceous material to completely or partially volatilize, converting it completely or partially into CO, and itself into CO. In the final part of the lower section, the non-volatile carbonaceous residue undergoes thermal reversal, is cooled by heated gases, and deposits on grid 1.5.

[0086] Similarly, in this case, regarding the gas phase, in the lower section A, carbon dioxide and oxygen are blown together into the fan 8 and preheated in the heating unit 9 (in this case, the heating unit 9 is only used to start the device 1), and supplied from below through the opening 1.17 into the interior of the lower section A. They rise countercurrently and encounter the hot solid material, and are heated to the temperature that activates the exothermic oxidation reaction.

[0087] [R3] C + 0.5O2 = CO

[0088] When CO2 is generated in situ in lower section B without being supplied, reaction [R3] combines with the exothermic oxidation reaction:

[0089] [R4] C + O2 = CO2

[0090] In this case, the exothermic reaction [R3], which may be associated with reaction [R4], can also heat the gas to a temperature higher than that of the solid particles until the oxygen is completely consumed and a sufficiently high temperature is reached, preferably at least 500°C, more preferably at least 600°C, and even more preferably 700°C, to allow the endothermic reaction [R1] to occur, after which the gas slowly begins to cool by transferring heat to the carbon-containing fresh material entering the head of the lower section A.

[0091] The gas exiting from the lower section A passes through the dust collector 1.3, and is filtered into the upper section B, where the reaction [R2] occurs, producing hydrogen and partially reforming carbon monoxide into CO2, so that the effluent exits at a temperature not lower than 620°C, thereby shifting the reaction appropriately to the right.

[0092] According to another embodiment of the method of the invention performed in apparatus 1, the following situation can be provided: the carbonaceous material in droplet or spray form can move in an equicurrent manner according to techniques known to a skilled person in the operation of a spray dryer (DiPretoro, Manenti, 2020). In this case, the gas gradually cools, providing heat to the droplets, while the droplets themselves maintain their constant temperature, equal to the evaporation temperature of the liquid, until evaporation is complete. The solid after drying the solvent behaves in the same way as the solid raw material, volatilizing and heating according to its own physicochemical properties (Biot number).

[0093] The RBF process, when carried out in endothermic mode, or when stage a) is carried out in the absence of oxygen using fresh solid carbonaceous material and in device 1, includes the following operating modes.

[0094] In the lower section A, fresh solid carbonaceous material is fed to the head of the lower section A by means of a screw conveyor 7 and gradually descends, coming into contact with the hot gas rising through the lower section (A) under different thermal conditions, exchanging heat and mass, so that in the uppermost part of the lower section, any moisture that may be present in the fresh solid carbonaceous material is removed. In the lower part, the dried carbonaceous material is rapidly heated further, encountering increasingly hot gas and reacting in this area [R1], where the hot gas containing CO2 causes the carbonaceous material to completely or partially volatilize, completely or partially converting it into CO, and itself into CO. In the last part of the lower section, the non-volatile carbonaceous material undergoes thermal reversal towards the gas due to the high Biot number, the inside is hotter than the outside, heating the gas, and is deposited on the grid (6) as carbonaceous residue material.

[0095] In the lower section A, before contacting the fresh carbon-containing material, CO2 is externally heated by heating unit 9 until it reaches a temperature of not less than 650°C, preferably equal to at least 700°C, more preferably above 800°C, and even more preferably above 900°C. From the first contact with the solid, the gas begins to cool in a monotonous manner, transferring heat to the fresh carbon-containing material.

[0096] The gas exiting from the lower section A passes through the dust collector 1.3, and is filtered into the upper section B, where a reaction [R2] occurs, producing hydrogen and partially reforming carbon monoxide into CO2, so that the effluent exits at a temperature not lower than 620°C.

[0097] Figure 4B This indicates that when stage a) takes place in the absence of oxygen... Figure 1 The diagram of container 1.1 shows that the lower section A and the upper section B are divided into different areas according to what happens inside them.

[0098] In the same attached figure, the area designated 1.4 in the lower section A of container 1.1 is also divided into corresponding areas for reverse Bourdon and solid preheating. In both cases, the already heated CO2 is cooled by transferring heat to the solids to allow the reaction to take place in the lower part [R1] and the fresh solids leaving the screw conveyor 1.7 are preheated in the upper part. Non-volatile residues are deposited on the grid 1.6. Figure 4A The height (in meters) of the gas and carbonaceous solid material in unit 1.1 is shown as a function of temperature (in °C) in the form of a graph. Starting from the bottom, note that the CO2 stream has a continuously decreasing temperature due to the endothermic nature of the reaction [R1] and the heat exchange between the hot CO2 and the cooler solid. Conversely, the solid gradually descending into the unit becomes hotter, gradually encounters the hotter gas, and evaporates at a gradually faster rate. Similarly, in this case, the dashed line represents the temperature of the gas in section B of the container if it comes into contact with a spray of water or water vapor at a lower temperature than that of the catalytic bed 1.2 where the Fontana reaction occurs.

[0099] The RBF process, in other words, the method of the present invention, when it further includes stage b1), can provide: CO2 that is not reacted in stage a) and therefore not reacted in reaction [R1], as well as CO2 formed in reaction [R2], which can be removed by conventional techniques at the end of reaction [R1] and at the end of reaction [R2], or removed only at the end of reaction [R2] and recycled to stage a) upstream of reaction [R1].

[0100] The same applies when this method is performed in device 1 and unit 1.1.

[0101] In fact, when needed, the gas can leave unit 1.1, undergo not only purification but also heat treatment, and then be returned to the unit.

[0102] This type of method is shown in its preferred form as follows: Figure 3 middle.

[0103] Conventional separation techniques include those using amine absorption, softening, scrubbing, water column, pressure swing adsorption, etc.

[0104] exist Figure 3In the embodiment of the method of the present invention shown, it is carried out in a self-heating mode and therefore in the presence of oxygen in stage a). In reaction [R1], hot CO2 volatilizes the carbonaceous material and partially oxidizes it to CO according to reaction [R1], and CO2 is reduced by an equimolar amount according to the same reaction [R1]. The hot gas stream leaving the reaction zone [R1] containing CO and CO2 is purified from CO2 using the conventional techniques described above. The removed CO2 is recycled upstream of stage a), where the CO purified in stage b1) reacts with water or steam according to reaction [R2] to produce H2 and CO2, the latter of which is separated from the syngas using conventional techniques and recycled upstream of stage a).

[0105] exist Figure 3 It is also envisioned that the final stage of purification would also allow for the removal of water formed in reaction [R2].

[0106] According to a preferred embodiment of the RBF process carried out in the absence of oxygen when the reaction [R1] in stage a) is carried out at a temperature greater than or equal to 900°C, the gas stream leaving stage a) has a low or no CO2 content, in which case CO2 removal is carried out only on the gas leaving reaction [R2].

[0107] exist Figure 5 Furthermore, it is envisioned that during this purification stage, water is also removed from the reaction products and recycled to stage b1) upstream of reaction [R2].

[0108] The method of the present invention may include both stage b1) and stage b2).

[0109] The Fontana reaction [R2] is typically carried out under mild conditions to avoid excessively increasing the CO2 content in the final syngas mixture. This means that the RBF process yields syngas with low S and SN values, which is not optimal for the primary synthesis of high-value chemicals such as methanol and dimethyl ether (Bozzano, G., Manenti, F., Efficient methanol synthesis: Perspectives, technologies and optimization strategies, Progress in Energy and Combustion Science, 2016, 56, pp. 71–105).

[0110] The water electrolysis stage b2) allows the ratio of S to SN to be adjusted to be higher, even reaching a value of SN to S = 2.

[0111] Therefore, the object of the present invention is a method in which, in addition to stage b1), stage b2) is also performed, thereby feeding water vapor into the electrolyzer, where pure oxygen and hydrogen are generated, and adding hydrogen and unreacted water to the gas leaving the reaction [R2].

[0112] A preferred embodiment of this method is shown in Figure 6 In stage a), the reaction proceeds in the absence of oxygen. The thermal CO2 in reaction [R1] is reduced to CO, and the effluent leaving stage a) is preferably purified after the addition of hydrogen from water electrolysis and the removal of unreacted water vapor, wherein CO2 is removed and fed into stage a). In this purification stage, the water formed in reaction [R2] is also preferably removed.

[0113] The method of the present invention can involve the case where stage b) consists only of stage b2).

[0114] This category also includes, for example Figure 7 The method according to the invention, wherein stage a) is carried out in the absence of oxygen, in reaction [R1], thermal CO2 is reduced to CO by volatilization and oxidation of a portion of the carbon present in the solid and / or liquid residue. The conversion occurs with partial or complete reduction of CO2. At the outlet of reaction [R1], the CO stream is mixed with hydrogen from the electrolyzer until an optimal S ratio is achieved. A downstream purification stage may be used to remove residual or excess CO2 depending on the intended use of the syngas. CO2 is recycled to stage a).

[0115] In this case, preferably, unreacted water in the electrolyzer is also removed and recycled back to the front of the electrolyzer, thus upstream of stage b2).

[0116] Another embodiment of the method of the present invention is described in Figure 8 Phase b) is identical only to phase b2) which is carried out under self-heating conditions.

[0117] The pure oxygen produced in the electrolyzer is supplied to stage a) for thermal self-support. CO2 and carbonaceous residue react according to the reverse Bourdon reaction [R1]. The effluent leaving stage a) is directly mixed with hydrogen from the electrolyzer in stage b2). The resulting gas mixture is sent for purification to remove CO2 (which is recycled back to stage a) and water (which is recycled back to the electrolyzer). The amounts of oxygen and hydrogen produced by the electrolyzer are stoichiometrically unsuitable for the purposes described above. To obtain, for example, the amount of hydrogen required to completely reduce CO and CO2 leaking from the unit, a higher amount of oxygen than the unit itself requires in the volatile matter removal section, taking into account the stoichiometry of the electrolysis reaction, is needed to thermally support itself. In other words, the nature of the invention would result in an excess of oxygen production if all the hydrogen required for the complete conversion of the gaseous effluent into chemicals were to be produced by electrolysis, taking into account the stoichiometry of the electrolysis reaction itself.

[0118] Figure 9 It shows the relationship with Figure 8 Another implementation of a similar method provided in [the text] only provides stage b2 in self-heating mode. Again, in this case, oxygen generated in the electrolyzer is fed into stage a). However, this method is similar to... Figure 8 The difference shown is that it does not provide a purification stage, and therefore does not even provide CO2 or water recycling to the electrolyzer or stage a).

[0119] Figure 10a illustrates a preferred embodiment in which stage b) coincides only with stage b2) in which oxygen is recycled to stage a), and this embodiment only provides the removal of water from the hydrogen before mixing it with the effluent from reaction [R1]. The removed water is recycled upstream of the electrolyzer.

[0120] Figure 10b describes the relationship with Figure 10A The same method is shown, the only difference being that in this case, only carbon-containing materials are supplied in stage a); therefore, there is no CO2 formed in situ by reacting with oxygen at high temperature according to [R4].

Claims

1. A method for producing syngas from carbonaceous residue materials, comprising the following stages: - Stage a), comprising reaction [R1], wherein a carbon-containing material is reacted with carbon dioxide according to the following reaction scheme to obtain carbon monoxide: [R1] CO2 + C = 2CO; -In stage b), hydrogen is produced and added to the carbon monoxide obtained in stage a) to obtain syngas. Phase b) includes at least one of the following phases: b1) According to the following reaction scheme, carbon monoxide from the previous stage is reacted with water vapor to obtain carbon dioxide and hydrogen: [R2] CO + H2O = CO2 + H2 b2) Hydrogen is produced by the electrolysis of water and added to the carbon monoxide from stage a).

2. The method according to claim 1, wherein the temperature at which the reaction [R1] is carried out is preferably at least 600°C, at least 700°C, preferably at least 800°C, and preferably at least 900°C.

3. The method according to claim 1 or 2, wherein the temperature of the reaction [R2] is preferably not less than 620°C, and more preferably not less than 650°C.

4. The method according to any one of claims 1 to 3, wherein the temperature range of stage b2) is 100°C to 900°C, preferably 500°C to 900°C, more preferably 800°C to 900°C.

5. The method according to any one of claims 1 to 4, wherein it is carried out at a pressure of 1 bar to 200 bar, preferably 1 bar to 100 bar, more preferably 20 bar to 100 bar, and includes the use of steam or water under similar pressure conditions.

6. The method according to any one of claims 1 to 5, wherein stage a) is carried out in the presence or absence of oxygen.

7. The method according to claim 6, wherein it is carried out in the presence of oxygen, and in stage a), the CO2 used in reaction [R1] is formed in situ according to the following reaction: [R4] C + O2 = CO2 Therefore, in stage a), carbon-containing materials are supplied in the absence of CO2.

8. The method of claim 6, wherein it is carried out in the absence of oxygen, and an external source of carbon dioxide is used in stage a).

9. The method according to any one of claims 1 to 8, wherein stage b) comprises or consists of stage b1).

10. An apparatus (1) comprising: - Unit (1.1), which consists of a generally cylindrical sealed container, the sealed container comprising an upper section (B) and a lower section (A) separated from each other by a dust collector (1.3), wherein: Upper section (B) includes: • Fixed catalytic bed (1.4), • A gas outlet (1.10) is arranged on the side above the catalyst bed (2). • A water inlet (1.11) is configured on the side, and a water distributor (1.12) is configured inside the upper section (B), parallel to the dust collector (1.3) and above the dust collector (1.3). • An inlet (1.13) at the top of the upper section (B) for loading fresh catalyst, and an outlet (1.14) on the side of the upper section to allow removal of spent catalyst. The next section (A) includes: • A device for introducing fresh carbon-containing materials (1.7) • A bed of non-volatile carbonaceous residue material (1.5); • A grid or perforated plate (1.6) for separating the non-volatile carbonaceous residue material and allowing it to be removed by means of a hopper (1.16) disposed below the grid or perforated plate and connected to an outlet (1.15) disposed at the bottom of the lower section (B); • An inlet (1.17) for the reactant gases (CO2 and possibly O2) is configured below the grid or perforated plate (1.6); - A blower (8) is directly connected to a heating unit (9), which is in turn connected to an inlet (1.17) for reaction gases located at the bottom of the lower section (A) of the unit (1.1).

11. The apparatus according to claim 10, wherein when the carbon-containing fresh material is solid, the means (1.7) for distributing it is a screw conveyor, and when the carbon-containing fresh material has a fluid consistency, a slurry pump connected to the loading line is used and a distributor or sprayer is used to distribute the carbon-containing material inside the lower section (A).

12. The method of claim 9, wherein stage a) is carried out in the apparatus of claim 10 or 11 in the presence of oxygen, comprising the following operational stages: 1-Lower Section (A) 1.1 Solid carbon-containing materials As the solid carbon-containing fresh material is fed into the head of the lower section (A) via the screw conveyor (1.7) and gradually descends, it comes into contact with the gas rising through the lower section (A) under different thermal conditions, exchanging heat and mass, so that in the highest part of the lower section, any moisture present in the solid carbon-containing fresh material is finally removed. In the lower part, the carbon-containing dry material is rapidly further heated and encounters increasingly hot gas, and a [R1] reaction occurs in this area, in which the hot gas containing CO2 causes the carbon-containing material to completely or partially volatilize, converting it completely or partially into CO, and itself into CO. In the last part of the lower region, the non-volatile carbon-containing residue material undergoes thermal reversal compared to the gas, the interior of the carbon-containing material is hotter than the exterior, heating the gas and depositing on the grid 1.

5. 1.2 Gaseous materials Carbon dioxide and oxygen are blown into the blower (8) and preheated in the heating unit (9), which is used only to start the equipment (1) in this case. They are supplied from below through the opening (1.17) into the lower section (A). They rise countercurrently and encounter the hot solid material, and are heated to the temperature that activates the exothermic oxidation reaction. [R3] C + 0.5O2 = CO When CO2 is not supplied but is generated in situ in the lower section (B), reaction [R3] combines with the exothermic oxidation reaction: [R4] C + O2 = CO2 The exothermic reaction [R3] may be associated with reaction [R4], which can heat the gas to a temperature higher than that of the solid particles until the oxygen is completely consumed and a sufficiently high temperature is reached, at least 600°C, preferably 700°C, more preferably 800°C, or even more preferably 900°C, to allow the endothermic reaction [R1] to occur, after which the gas begins to cool by transferring heat to the carbon-containing fresh material entering the head of the lower section (B); 2-Upper Section (B) The gas exiting from the lower section (A) passes through the dust collector (1.3), thereby filtering it into the upper section (B), where a reaction [R2] occurs, in which hydrogen is produced and CO2 is partially reformed, such that the effluent exits at a temperature not lower than 620°C, preferably 650°C.

13. The method of claim 9, wherein it is carried out in the apparatus of claim 10 or 11 in the presence of oxygen. Includes the following stages: 1-Lower Section (A) 1.1 Carbon-containing materials in paste form When the carbon-containing fresh material has a paste-like consistency, it enters the lower section (A) by means of a slurry pump and a loading line, and is distributed by means of a distributor in the form of spray or droplets from above and gradually falls down, coming into contact with the hot air rising through the lower section (A) under different thermal conditions, exchanging heat and mass, so that in the upper part of the lower section, any moisture present in the paste-like carbon-containing fresh material is finally removed. In the lower part, the carbon-containing dried material is further heated and rapidly encounters increasingly hot gas, and a [R1] reaction occurs in this area, in which the hot gas containing CO2 causes the carbon-containing material to completely or partially volatilize, completely or partially converting it into CO, and reducing the CO2 in the gas to CO. In the last part of the lower region, the non-volatile carbon-containing material undergoes thermal reversal relative to the gas, becoming hotter inside than outside, heating the gas, and is deposited on the grid (5) as a residue material containing ash. 1.2 Gaseous materials Carbon dioxide and oxygen are blown into the blower (7) and preheated in the heating unit (8) used only for starting the equipment (1). They are supplied from below through the inlet (1.17), rise counter-currently through the lower section, and encounter the hot carbonaceous material in paste form, and are heated until an exothermic oxidation reaction is activated. [R3] C + 0.5O2 = CO When CO2 is not preheated or supplied, but is generated in situ in the lower section (B), reaction R3 combines with the exothermic oxidation reaction: [R4] C + O2 = CO2 The exothermic reaction [R3] may be associated with reaction [R4], which can heat the gas to a temperature higher than that of the granules in paste form until the oxygen is completely consumed and a sufficiently high temperature is reached, at least 600°C, preferably at least 700°C, more preferably at least 800°C, and even more preferably 900°C, to allow the endothermic reaction [R1] to occur, after which the gas begins to cool slowly by transferring heat to the carbon-containing fresh material entering the head of the lower section (A); 2-Upper Section (B) The gas leaving the lower section (A) passes through the dust collector (1.3), thereby filtering it into the upper section (B), where a reaction [R2] occurs, producing hydrogen and partially reforming CO2, so that the effluent leaves at a temperature not lower than 620°C, preferably 650°C.

14. The method of claim 9, carried out in the absence of oxygen in the apparatus of claim 10 or 11, comprising the following steps: 1-Lower Section (A) 1.1-Solid carbon-containing materials When the carbon-containing fresh material is in a solid state, it is fed to the head of the lower section (A) by a screw conveyor (7) and gradually descends, coming into contact with the hot gas rising through the lower section (A) under different thermal conditions, exchanging heat and mass, so that in the upper part of the lower section, any moisture present in the solid carbon-containing fresh material is eventually removed, and in the lower part, the carbon-containing dry material is rapidly heated further, encountering increasingly hot gas and reacting in this area [R1], the hot gas containing CO2 causes the carbon-containing material to completely or partially volatilize, completely or partially converting it into CO, CO2 present in the CO gas, in the lower part of the lower area, the carbon-containing material that has not been completely volatilized undergoes thermal reversal compared to the gas, the inside of the carbon-containing material is hotter than the outside (high Biot number), heating the gas, and is deposited on the grid (6) as a non-volatile residue material; 1.2-Gaseous materials Before coming into contact with the carbon-containing fresh material, CO2 is heated externally by the heating unit (9) until it reaches a temperature of not less than 650°C, preferably equal to at least 700°C, more preferably above 800°C, and even more preferably above 900°C. Then, in the upper part of the lower section, the gas begins to cool by transferring heat to the carbon-containing fresh material. 2-Upper Section (B) The gas leaving the lower section (A) passes through the dust collector (3), thereby filtering it into the upper section (B), where a reaction [R2] occurs, producing hydrogen and partially reforming carbon monoxide into CO2, so that the effluent leaves at a temperature not lower than 620°C, preferably 650°C.

15. The method according to any one of claims 9, 12-13, carried out in the presence of oxygen, wherein in stage a), thermal CO2 volatilizes the carbonaceous material and partially oxidizes it to CO according to reaction [R1], and CO2 is reduced by an equimolar amount according to the same reaction [R1], the hot gas stream leaving the reaction zone [R1] containing CO and CO2 is purified from CO2 by conventional techniques, the separated CO2 is recycled to the upstream of stage a), the purified CO reacts with water or steam according to reaction [R2] to produce H2 and CO2, which are separated from the syngas by conventional techniques and recycled to the upstream of stage a).

16. The method according to any one of claims 9 or 14, wherein when stage a) is carried out in the absence of oxygen and reaction [R1] is carried out at a temperature greater than or equal to 900°C, the gas stream leaving stage a) is CO2-poor or CO2-free, in which case CO2 removal is performed only on the gas leaving reaction [R2].

17. The method according to any one of claims 1 to 9, 12 to 16, wherein stage b) comprises stage b1) and stage b2), or consists of stage b1) and stage b2).

18. The method according to claim 17, wherein stage a) is carried out in the absence of oxygen, and stage b2) is carried out to increase S and SN in the syngas, whereby steam is also fed into an electrolyzer to generate pure oxygen and hydrogen, hydrogen from which unreacted steam may have been removed is added to the gas leaving reaction [R2] and sent for purification to remove CO2, and CO2 is recycled to stage a) before reaction [R1] occurs.

19. The method according to any one of claims 1 to 8, wherein stage b) includes stage b2) or consists of stage b2).

20. The method according to claim 19, wherein stage a) is carried out in the absence of oxygen, in reaction [R1], thermal CO2 is reduced to CO by partially volatilizing and oxidizing the carbon present in the solid and / or liquid residue, while CO2 is partially or completely reduced.

21. The method of claim 19, wherein oxygen formed in the electrolysis of water is supplied to stage a), and hydrogen that may be purified from water is added downstream of reaction [R1].

22. The method according to claim 20 or 21, wherein the gas mixture leaving reaction [R1] and containing hydrogen from electrolysis is purified to remove CO2, and the CO2 is recycled to stage a).

23. The method according to claims 21 and 22, wherein only carbon-containing materials are supplied in stage a), and the CO2 used in reaction [R1] is formed in situ according to the following reaction: [R4] C + O2 = CO2.

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