Process for methanol production

Abstract

The invention relates to a method for methanol production, wherein the method comprises the steps of: (a) supplying one or more gaseous input streams to a plasma reactor, wherein the one or more gaseous input streams comprise at least CO2, H2O and CH4; (b) igniting a plasma in the plasma reactor, thereby reacting the CO2, H2O and CH4 and forming a synthesis gas comprising CO and H2; (c) supplying the synthesis gas to a methanol reactor, wherein the CO and H2 in the synthesis gas are at least partially converted to methanol in the methanol reactor.

Description

Technical Field

[0001] This invention relates to a method for optimizing syngas for methanol production. Background Technology

[0002] Dry reforming of methane (DRM) in an atmospheric pressure plasma reactor has been studied as a promising alternative to traditional methods. However, the syngas produced by DRM has a low H2 / CO ratio, which limits its use in fuel production.

[0003] WO2020223789 describes a method in which carbon dioxide, methane, and steam react at high temperatures (bi-reforming of methane) to form syngas, which can then be used in a methanol production facility. However, it has been found that the disclosure of WO2020223789 does not adequately address the aforementioned problems.

[0004] Furthermore, the implementation of this process in plasma reactors has not been fully explored. The type of plasma reactor and its operating power level can significantly affect the performance and energy efficiency of this process. Summary of the Invention

[0005] The present invention and its embodiments are intended to provide solutions to one or more of the aforementioned disadvantages. Therefore, the present invention relates to the method according to claim 1. Preferred embodiments of the apparatus are shown in any one of claims 2 to 15.

[0006] This invention relates to a method for producing methanol using a plasma reactor. The method includes supplying a gaseous input stream containing CO2, H2O, and CH4 to the plasma reactor, igniting the plasma to react the gas and form syngas. The inventors have discovered that, in order to obtain optimal syngas for fuel production, it is advantageous for the total amount of H2O in the input gas stream to be at least 40% by volume.

[0007] This specific ratio is important because it optimizes syngas formation, thereby facilitating subsequent methanol production. In this case, the syngas is a favorable mixture for methanol synthesis due to the H2 to CO volume ratio being close to 2 and the absence of soot generation (ideal conditions for methanol production). Therefore, the method provides an innovative approach to methanol production that utilizes a plasma reactor and a specific gas input ratio to optimize the process.

[0008] This invention provides an efficient, cost-effective, and resource-optimized method. By utilizing waste biogas as a single gaseous input stream and eliminating the need for biogas purification steps, this invention transforms waste into value and contributes to a more sustainable and circular economy.

[0009] The method for methanol production described in the embodiments provides a sustainable and efficient solution for converting greenhouse gases into valuable commodity precursors.

[0010] The method for producing methanol of the present invention offers several advantages over conventional methods. Using biogas as a source not only provides a renewable and sustainable method for methanol production but also reduces the environmental impact associated with conventional fossil fuel-based methods. By eliminating the separation stages typically required in conventional methods, the present invention also reduces energy consumption and costs associated with methanol production. Detailed Implementation

[0011] Unless otherwise defined, all terms used in disclosing this invention (including technical and scientific terms) have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Definitions of terms are incorporated to provide further guidance and to better understand the teachings of this invention.

[0012] As used herein, the following terms have the following meanings: As used herein, the terms “gliding arc (GA),” “glow discharge (GD),” “radio frequency plasma (RF),” “microwave plasma (MW),” “inductively coupled plasma (ICP),” “capacitor-coupled plasma (CCP),” and “dielectric barrier discharge (DBD)” refer to plasma generating apparatuses as will be understood by those skilled in the art.

[0013] As used herein, “a,” “an,” and “the / said” refer to both singular and plural entities, unless the context clearly indicates otherwise. For example, “a compartment” refers to one or more compartments.

[0014] As used herein, the term "about" refers to measurable values ​​(e.g., parameters, quantities, durations of time, etc.) and is intended to cover variations of up to + / -20%, preferably up to + / -10%, more preferably up to + / -5%, even more preferably up to + / -1%, and still more preferably up to + / -0.1%, provided that such variations are suitable for carrying out the disclosed invention. However, it should be understood that the value modified by "about" is itself specifically disclosed.

[0015] As used herein, “comprise”, “comprising”, “comprises” and “comprised of” are synonymous with “include”, “including”, “includes” or “contain”, and are inclusive or open-ended terms that indicate the presence of the following content (e.g., components) but do not exclude or preclude the presence of other parts, features, elements, members or steps known in the art or disclosed herein that are not mentioned.

[0016] Furthermore, the terms first, second, third, etc., in the specification and claims are used to distinguish similar elements and are not necessarily used to describe order or chronological sequence, unless otherwise stated. It should be understood that such terms are interchangeable where appropriate, and the embodiments of the invention described herein can operate in a sequence different from that described or shown herein.

[0017] The range of values ​​expressed in terms of endpoints includes all numbers and fractions contained within that range, as well as the endpoints themselves.

[0018] Unless otherwise defined, the expressions “weight%”, “weight percentage”, “%wt”, or “wt%” used throughout the instructions refer to the relative weight of each component with respect to the total weight of the formulation. The expressions “vol%”, “vol%”, and “volume percentage” also apply.

[0019] The meaning of the terms “one or more” or “at least one” (e.g., one or more or at least one member of a group of members) is clear in itself; as a further example, the term specifically includes referring to any one of the members, or referring to any two or more of the members, such as any ≥3, ≥4, ≥5, ≥6 or ≥7 of the members, or even all of the members.

[0020] Unless otherwise defined, all terms used in disclosing this invention (including technical and scientific terms) have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Definitions of terms used in this specification are incorporated to provide further guidance and to better understand the teachings of this invention. The terms or definitions used herein are for illustrative purposes only.

[0021] Throughout this specification, the terms "one embodiment" or "an embodiment" refer to a specific feature, structure, or characteristic described in connection with that embodiment being included in at least one embodiment of the invention. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment, but may refer to the same one. Furthermore, as will be apparent to those skilled in the art from this disclosure, specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Moreover, while some embodiments described herein include features not included in other embodiments, combinations of features from different embodiments are intended to fall within the scope of the invention and form different embodiments, as understood by those skilled in the art. For example, in the appended claims, any claimed embodiments can be used in any combination.

[0022] In a first aspect, the present invention relates to a method for hydrocarbon production, preferably methanol production.

[0023] The method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O, and CH4; and b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2.

[0024] In a preferred embodiment, the one or more gaseous input streams include: - A total amount of at least 40% by volume of H2O; or - A total amount of at least 30% by volume of H2O, wherein the specific energy input of the plasma reactor is at least 200 kJ / mol.

[0025] In a preferred embodiment, the volume ratio of the total amount of CH4 to the total amount of CO2 contained in the gaseous input stream is at least 1.8, preferably at least 2, and more preferably at least 2.5.

[0026] The syngas obtained by this method has been proven to be highly suitable for methanol production. Therefore, in another preferred embodiment, the method includes step c): supplying the syngas to a Fischer-Tropsch reactor, preferably a methanol reactor.

[0027] In a particularly preferred embodiment, the method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor.

[0028] In the plasma reactor, ignition of the plasma causes the CO2, H2O, and CH4 to react and form syngas. It has been shown that the conversion of CO2 and CH4 in the plasma reactor (dry methane reforming (A)) yields low-quality syngas containing CO and H2: the H2 to CO molecule ratio is only 0.5-0.6, which limits its use in fuel production.

[0029] (A)

[0030] By adding water vapor (gas phase) to the gas mixture, the inventors have been able to alter the H2 / CO ratio. When water is present in the mixture, methane steam reforming (B) occurs in addition to dry methane reforming. This combination is known as BRM (double methane reforming (C)).

[0031] (B) (C) When the resulting syngas is preferably used to produce methanol according to reaction (D), the optimal molar ratio of CO to H2 in the syngas is 1:2.

[0032] (D)

[0033] Reaction (D) shows that a CO to H2 molar ratio of 1:2 is the optimal mixture for methanol synthesis. Although reaction (C) indicates that a molar ratio of 3:2:1 (stoichiometric ratio) of methane, water vapor (gas phase), and carbon dioxide should be used to obtain a CO to H2 molar ratio of 1:2, the inventors have now discovered that a stoichiometric ratio of 3:2:1 (16.6% CO2 - 50% CH4 - 33.3% H2O) results in excessive soot generation.

[0034] The inventors have discovered that soot generation can be reduced by increasing the specific energy input (SEI) (i.e., higher power or lower flow rate) or by increasing the amount of water vapor supplied to the plasma reactor.

[0035] In one implementation, the method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor. The one or more gaseous input streams contain at least 40% by volume H2O.

[0036] In one implementation, the method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor. The one or more gaseous input streams contain at least 30% by volume of H2O, and the specific energy input (SEI) of the plasma reactor is at least 200 kJ / mol.

[0037] In one embodiment, the one or more gaseous input streams contain a total amount of at least 20% by volume, preferably at least 25% by volume, more preferably at least 30% by volume, even more preferably at least 35% by volume, even more preferably at least 40% by volume, even more preferably at least 45% by volume of H2O.

[0038] In one embodiment, the one or more gaseous input streams contain a total amount of 20% to 70% by volume, preferably 25% to 65% by volume, more preferably 30% to 50% by volume, even more preferably 35% to 50% by volume, even more preferably 40% to 50% by volume of H2O.

[0039] In one embodiment, the one or more gaseous input streams contain a total amount of H2O ranging from 20% to 70% by volume, preferably from 25% to 65% by volume, more preferably from 30% to 50% by volume, even more preferably from 30% to 45% by volume, and even more preferably from 30% to 40% by volume.

[0040] This specific input optimizes syngas formation, thereby facilitating subsequent methanol production. In this case, the syngas is a favorable mixture for methanol synthesis due to the H2 to CO volume ratio being close to 2 and the absence of soot generation, representing ideal conditions for methanol production. Therefore, the method provides a route for methanol production that utilizes a plasma reactor and a specific gas input ratio to optimize the process.

[0041] This system facilitates the direct and immediate conversion of the main inputs (i.e., CO2, H2O, and CH4) into syngas. This eliminates the need for any preparatory steps or temporary storage, improves process efficiency, and ensures continuous flow throughout the process. Its performance advantages have been observed to exceed those achieved by operating at stoichiometric ratios, making it an enhanced, flexible, and environmentally friendly alternative to traditional gas reforming methods.

[0042] In a preferred embodiment, the one or more gaseous input streams contain a total amount of at least 10% by volume, preferably at least 20% by volume, more preferably at least 30% by volume, even more preferably at least 35% by volume, even more preferably at least 40% by volume of CH4.

[0043] In a preferred embodiment, the one or more gaseous input streams contain a total amount of CH4 ranging from 10% to 70% by volume, preferably from 20% to 60% by volume, more preferably from 30% to 50% by volume, even more preferably from 35% to 45% by volume, and even more preferably from 40% to 45% by volume.

[0044] In a preferred embodiment, the one or more gaseous input streams contain a total amount of at least 5% by volume, preferably at least 10% by volume, of CO2.

[0045] In a preferred embodiment, the one or more gaseous input streams contain a total amount of 5% to 50% by volume, preferably 10% to 40% by volume, more preferably 10% to 30% by volume, and even more preferably 10% to 20% by volume of CO2.

[0046] In a preferred embodiment, the volume ratio of the total amount of H2O contained in one or more gaseous input streams to the total amount of CO2 and CH4 is at least 0.4, preferably at least 0.6, and more preferably at least 0.8.

[0047] In a particularly preferred embodiment, the method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor. The volume ratio of the total amount of CH4 to the total amount of CO2 contained in the gaseous input stream is at least 1.8, preferably at least 2, and more preferably at least 2.5, and the volume ratio of the total amount of H2O contained in one or more gaseous input streams to the total amount of CO2 and CH4 is at least 0.4, preferably at least 0.8.

[0048] In a particularly preferred embodiment, the volume ratio of the total amount of CO2, CH4 and H2O contained in the one or more gaseous input streams is 0.9-1.1:2.8-3.0:3.1-3.3 or 0.9-1.1:1.8-2.0:2.3-2.5.

[0049] In a particularly preferred embodiment, the method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor. The gaseous input stream contains 35% to 45% CH4, 10% to 20% CO2, and 40% to 50% H2O.

[0050] In a particularly preferred embodiment, a gaseous input stream, wherein the gaseous input stream is biogas, is supplied to the plasma reactor. In this embodiment, methane, carbon dioxide, and water vapor are all present in the biogas and are supplied to the plasma reactor.

[0051] The biogas input stream is a renewable energy source, typically produced from raw materials such as biological waste, feces, municipal solid waste, sewage, and green waste. This biogas is generated through an anaerobic digestion process by microorganisms within a biochamber or bioreactor. The resulting gas composition is primarily a mixture of CH4, CO2, and trace amounts of H2O, H2S, and H2. In this preferred embodiment, the composition of the biogas used can vary, but it typically consists mainly of CH4, CO2, and trace amounts of H2O.

[0052] Typically, gas mixtures are purified through separation stages (such as distillation or pressure swing adsorption). This removes undesirable products such as CO2 and H2O. This approach increases costs because the separation process can be energy-intensive. Furthermore, CO2 gas is emitted, which is undesirable. While CO2 gas can be captured, this further increases the price of the CH4 product.

[0053] The inventors have now found a solution to this problem by eliminating the separation stage and replacing it with a specific plasma reactor that facilitates both dry and steam reforming of methane (also known as methane dual reforming).

[0054] Therefore, in this preferred embodiment, the method is characterized by supplying a single gaseous input stream, specifically biogas, in step a. This embodiment is particularly advantageous in terms of efficiency and resource optimization. The present invention allows for the direct use of biogas, thereby improving overall process efficiency. It eliminates the need for biogas purification steps, which typically require significant energy input and increase production costs. By eliminating these steps, the present invention not only saves energy but also reduces the overall cost of methanol production.

[0055] Furthermore, this invention converts waste biogas into valuable methanol, thereby achieving greater resource optimization. Biogas, typically composed of methane, carbon dioxide, and trace amounts of water, hydrogen sulfide, and hydrogen, is generally considered a waste product. However, using this invention, this waste product is converted into a valuable compound—methanol—which has numerous industrial applications. This not only increases the value of biogas but also helps reduce waste and promote a circular economy.

[0056] It should be understood that, in this specific embodiment, when a single gaseous input stream (specifically biogas) is supplied to the plasma reactor in step a, the above-mentioned proportions and compositions of one or more gaseous input streams also apply. For example, "the gaseous input stream contains at least 30% by volume of H2O" is equivalent to "the biogas contains at least 30% by volume of H2O".

[0057] In a particularly preferred embodiment, the method includes the following steps: a. Supplying a gaseous input stream to the plasma reactor, wherein the gaseous input stream is biogas, and wherein the gaseous input stream contains at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor.

[0058] The biogas used in this embodiment preferably has a relatively high water content compared to typical biogas containing only trace amounts of H2O. Preferably, the biogas contains at least 30% by volume, or even at least 40% by volume, of H2O.

[0059] Biogas with high water content can be generated from feedstocks or waste materials with high moisture content. The water content in biogas is largely influenced by the moisture content of the substrate used in the anaerobic digestion process.

[0060] In a preferred embodiment, the biogas is produced from food waste, sewage sludge, agricultural waste, animal manure, or aquatic biomass.

[0061] - Food waste: Food scraps and waste from households, restaurants, and the food processing industry typically have a high moisture content. After anaerobic digestion, the resulting biogas can contain a significant amount of water vapor.

[0062] - Sewage sludge: Anaerobic digestion of sewage sludge (the semi-solid material left after sewage treatment) can also produce biogas with high water content. This is because sewage sludge usually contains a high percentage of water.

[0063] - Agricultural waste: Certain types of agricultural waste (such as vegetable waste, green plant material, and fruit waste) have a high moisture content. When these materials undergo anaerobic digestion, the resulting biogas often has a high water vapor content.

[0064] - Animal manure: Manure from livestock such as cattle, pigs, and poultry contains a large amount of water. Anaerobic digestion of these materials not only produces biogas rich in methane, but also biogas containing a large amount of water vapor due to the initial moisture in the manure.

[0065] - Aquatic biomass: Materials such as algae and aquatic plants have high water content. When these biomass materials are used as feedstock for biogas production, the resulting gas can have a high water vapor content.

[0066] In another or other particularly preferred embodiment, two or more gaseous input streams are supplied to the plasma reactor, one of which is biogas and the other is pure CO2 or pure H2O. The term "pure" should be understood as "essentially made from...". Water containing small amounts of contaminants is therefore still considered "pure H2O". Preferably, "pure" means at least 85% by volume, more preferably at least 90% by volume, more preferably at least 95% by volume, and most preferably at least 99% by volume.

[0067] This implementation offers the advantage of allowing the addition of supplemental CO2 or H2O streams to achieve the desired chemical equilibrium, potentially leading to more efficient and effective methanol production. This implementation provides a significant advantage in terms of method flexibility because it can accommodate multiple gaseous input streams. This is particularly advantageous because it allows for the optimization of syngas yield and quality.

[0068] This implementation method is particularly useful when the biogas contains too little water or carbon dioxide. The inventors have discovered that the addition of water vapor promotes methane double reforming, thereby providing a more favorable syngas composition for subsequent fuel production.

[0069] If the biogas source contains too much CH4, which is detrimental to efficient operation, additional CO2 can be introduced during the capture stage. Conversely, if the biogas source contains insufficient H2O, additional H2O can be introduced.

[0070] In a particularly preferred embodiment, the method includes the following steps: a. Supplying two or more gaseous input streams to the plasma reactor, wherein the gaseous input streams contain at least CO2, H2O and CH4, and one of the gaseous input streams is biogas and the other gaseous input stream is CO2 or H2O, preferably H2O; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a Fischer-Tropsch reactor, preferably a methanol reactor.

[0071] In a particularly preferred embodiment, two or more gaseous input streams are supplied to the plasma reactor, one of which is biogas and the other is pure H2O (water vapor). In this embodiment, adding pure H2O as a separate gaseous input stream helps optimize the yield and quality of the syngas. Biogas typically contains only trace amounts of water, but the inventors have found that a larger amount of steam is preferred for obtaining the optimal syngas composition.

[0072] Water is preferably introduced into the reactor in the form of steam, which may come from a water tank or an equivalent water source. The water can be supplied via heated piping. In a preferred embodiment of the invention, the method includes using H2O from a liquid water tank. The liquid water from the tank is converted into steam, for example, via a boiler and / or heated steam piping.

[0073] The size of the water tank can vary depending on the scale of the operation, but preferably the tank is large enough to hold the sufficient amount of water required for continuous operation. The tank can be constructed from any suitable material capable of withstanding the heat and pressure involved in the conversion process.

[0074] In the preferred embodiment, pure H2O is dry steam (>100°C), but alternatively, wet steam (about 100°C) can also be used for operation.

[0075] It should be understood that, in this specific embodiment, when pure steam or carbon dioxide is supplied together with biogas in step a, the proportions and compositions of the one or more gaseous input streams described above also apply. For example, "the volume ratio of the total amount of H2O contained in the one or more gaseous input streams to the total amount of CO2 and CH4 is at least 0.3" will refer to the total amount of these components in the two streams.

[0076] Various types of plasma reactors exist in the art for plasma-based gas conversion. The plasma reactor according to this disclosure is designed for efficient and stable operation in glow discharge mode, which is typically characterized by a lower plasma temperature compared to arc discharge mode. More specifically, the plasma reactor according to this disclosure is designed to generate stable glow discharge plasma to achieve high gas conversion performance, such as for the conversion of greenhouse gases. As mentioned above, reactions of particular interest are the DRM process for the simultaneous conversion of carbon dioxide and methane. While the plasma reactor according to this disclosure is particularly well-suited for operation in glow discharge mode, it may also operate in spark, arc, or transition discharge modes depending on specific operating settings (e.g., the power supply used) and gas flow patterns.

[0077] The plasma reactor used in this invention is preferably an atmospheric pressure plasma reactor, because they typically operate at atmospheric pressure.

[0078] In a preferred embodiment, the plasma reactor operates at atmospheric pressure.

[0079] In another or other embodiment, the plasma reactor is operated at a temperature of 2500K to 5000K, more preferably 3000K to 4500K, and most preferably about 3500K. This high temperature is preferably used to promote the reaction that leads to the formation of syngas.

[0080] In a preferred embodiment, the plasma reactor includes a plasma generating device selected from the following list: - Glide arc (GA) - Glow discharge (GD) - Radio frequency plasma (RF) - Microwave Plasma (MW) - Inductively Coupled Plasma (ICP) - Capacitively Coupled Plasma (CCP) - Dielectric barrier discharge (DBD).

[0081] In a more preferred embodiment, the plasma reactor includes a plasma generating device selected from the following list: - Glide arc (GA) - Glow discharge (GD) - Radio frequency plasma (RF) - Microwave Plasma (MW) - Dielectric barrier discharge (DBD).

[0082] Each of these reactor types possesses unique characteristics that can be used to improve the efficiency and effectiveness of the methane double reforming (BRM) process. In even more preferred embodiments, the plasma reactor includes a plasma generation device, which is a sliding arc (GA). Sliding arc reactors maintain stable discharge even at high flow rates. This characteristic is particularly advantageous in the case of BRM, where the flow rate of the gas mixture can be adjusted to optimize syngas production.

[0083] In another preferred embodiment, the plasma reactor includes a plasma generation device selected from sliding arc (GA) or glow discharge (GD) plasmas. These plasma types are particularly well-suited for direct plasma-driven gas reforming processes, including dry methane reforming (DRM), oxygen methane reforming, and double methane reforming (BRM). They can operate efficiently at atmospheric pressure while maintaining stable plasma conditions, enabling the high-conversion conversion of methane and carbon dioxide into syngas. Sliding arc and glow discharge plasmas promote efficient electron-driven dissociation of CH4 and CO2, facilitating the production of syngas in various reforming pathways without the need for catalysts. These plasma systems provide a versatile approach to reforming reactions, allowing optimization of the syngas composition by adjusting the CO2, O2, or H2O content in the input stream while maintaining high process efficiency and scalability.

[0084] Preferably, the plasma reactor is a closed-loop plasma reactor. A closed-loop plasma reactor ensures that the plasma discharge is confined to a controlled reaction environment, preventing undesirable interactions with external surfaces and maintaining consistent reaction conditions. More preferably, the plasma reactor is a closed-loop atmospheric pressure sliding arc or closed-loop atmospheric pressure glow discharge reactor. Compared to other types of plasma reactors, these reactor configurations have shown significantly higher conversion rates under direct plasma, non-catalytic conditions. Atmospheric pressure operation eliminates the need for a vacuum system, simplifies reactor design, and reduces energy consumption and maintenance requirements.

[0085] Furthermore, sliding arc (GA) and glow discharge (GD) plasma reactors offer several advantages over radio frequency (RF) and microwave (MW) plasma reactors. Specifically, GA and GD reactors exhibit simpler operating setups and require fewer specialized components (such as the complex impedance matching networks or waveguides necessary for RF and MW plasma systems). This simplicity translates into lower capital costs, easier scalability, and greater robustness for continuous operation. Additionally, GA and GD plasmas inherently generate moderate electron temperatures, which can efficiently drive DRM reactions without excessive energy loss, improving process sustainability.

[0086] By utilizing closed-loop atmospheric pressure sliding arc or glow discharge plasma reactors, this invention achieves an optimal balance between conversion efficiency, process stability, and system simplicity. These reactors enable a robust and scalable approach to direct plasma DRM, mitigating known challenges associated with plasma-catalyzed systems and maximizing the advantages of non-catalytic syngas production.

[0087] In a preferred embodiment, the plasma reactor is a closed-type atmospheric pressure glow discharge or sliding arc reactor, wherein the cathode-anode distance (defined as the shortest distance between the cathode and anode) is at least 10 mm, more preferably at least 20 mm, even more preferably at least 30 mm, even more preferably at least 40 mm, even more preferably at least 50 mm, even more preferably at least 60 mm, and most preferably at least 80 mm. In another preferred embodiment, the cathode-anode distance is at most 100 mm, more preferably at most 90 mm, even more preferably at most 80 mm, even more preferably at most 70 mm, even more preferably at most 60 mm, and most preferably at most 50 mm.

[0088] Increasing the distance between the anode and cathode raises the breakdown voltage in the plasma reactor, resulting in higher energy consumption per molecule of reformed gas. This increased energy input enhances the dissociation of CH4 and CO2, thereby improving conversion efficiency and syngas yield. A longer cathode-anode distance also prolongs the interaction time of the gases within the plasma region, which positively impacts the formation of CO and H2. However, excessive distance can lead to plasma discharge instability and increased electrode wear. Maintaining the cathode-anode distance within an optimized range of 50 mm to 80 mm allows for a balance between energy consumption, conversion efficiency, and plasma reactor stability, contributing to a robust and scalable reforming process.

[0089] In a preferred embodiment, the method involves causing the plasma reactor to operate at a rate of 1 L / min to 10 L / min. 6 Running at a flow rate of L / min.

[0090] In this embodiment, the plasma reactor is designed to handle a wide range of gas flow rates, thus making the system adaptable. Flow rate is a parameter in the operation of the plasma reactor that directly affects the residence time of the gas in the reactor, and consequently, the efficiency of the reforming reaction. The ability to operate at low flow rates (e.g., 1 L / min) makes this method suitable for small-scale operations where the amount of influent gas (e.g., biogas) produced is limited. Conversely, flow rates up to 10 L / min... 6 The ability to operate at high flow rates of L / min makes this method suitable for large-scale operations that generate large amounts of inlet gas (e.g., biogas).

[0091] In a more preferred embodiment, the plasma reactor is at 10 3 L / min to 10 5 Operating at a flow rate of L / min provides a balance between the residence time of the gas in the reactor and the efficiency of the reforming reaction.

[0092] The ability to operate the plasma reactor at varying flow rates allows this method to adapt to variable compositions of the influent gas stream (e.g., biogas). The composition of the biogas can vary depending on its source and the anaerobic digestion process. By adjusting the flow rate, this method can accommodate these variations while still producing syngas with the desired composition. This adaptability makes this method a versatile approach for producing methanol from biogas.

[0093] In a preferred embodiment, the specific energy input of the plasma reactor is at least 150 kJ / mol, preferably at least 200 kJ / mol.

[0094] In a preferred embodiment of the invention, the method is optimized by ensuring that the volume ratio of CO to H2 in the syngas obtained from the dual reforming process is 1.5 to 2.5, preferably 1.9 to 2.1. This optimal ratio is beneficial not only to the efficiency of methanol synthesis but also to the overall process efficiency and environmental impact. In a preferred embodiment of the invention, the method is optimized by ensuring that the volume ratio of H2 to CO in the syngas obtained from the dry reforming process is 1.0 to 3.0, preferably 1.2 to 2.8, more preferably 1.5 to 2.5, even more preferably 1.7 to 2.3, even more preferably 1.8 to 2.2, even more preferably 1.85 to 2.15, and most preferably 1.9 to 2.1. This optimal range is crucial for ensuring the efficiency of methanol synthesis and other hydrocarbon conversion processes, and is also crucial for optimizing the overall energy balance and environmental impact of the reforming process.

[0095] At the wider end of the range, when the H2 / CO ratio is 2.5 to 3.0, the syngas contains excess hydrogen, which can lead to poor carbon utilization and promote side reactions, such as the formation of methane via the Sabatier reaction. While higher hydrogen content can be advantageous for hydrogenation, additional CO supplementation or recycling is typically required to achieve the stoichiometric ratio needed for methanol production.

[0096] Conversely, when the H2 / CO ratio drops below 1.5, the syngas becomes hydrogen-poor, which can lead to incomplete methanol synthesis and increase the proportion of unreacted CO in the output stream.

[0097] As previously described, the dual reforming process involves the reaction of methane and carbon dioxide in a plasma reactor in the presence of steam. The resulting syngas is a mixture of carbon monoxide and hydrogen, which is subsequently preferably used for methanol production. Due to reaction (D), the optimal ratio for methanol synthesis is generally considered to be approximately 2:1.

[0098] The syngas produced by this process has a higher value than that obtained through the method described in WO2020223789. Due to its higher value, it can be directly used in the synthesis of fuel products such as methanol, thereby reducing the need for additional processing stages. This efficient utilization of syngas not only improves the overall productivity of the method but also reduces operating costs.

[0099] Methane dual reforming (BRM) can be enhanced by using catalysts that promote the conversion of methane, carbon dioxide, and water into syngas (H2 and CO). Catalysts suitable for BRM typically include transition metal-based catalysts such as nickel (Ni), cobalt (Co), and iron (Fe), as well as noble metals such as platinum (Pt), palladium (Pd), rhodium (Rh), and ruthenium (Ru), often supported on materials such as alumina (Al2O3), cerium oxide (CeO2), zirconium oxide (ZrO2), or magnesium oxide (MgO). These catalysts help lower the activation energy of the reaction, increase conversion efficiency, and enhance selectivity for syngas formation. While noble metals generally offer greater stability and resistance to carbon deposition, their high cost makes nickel-based catalysts a more common choice due to their cost-effectiveness, despite their susceptibility to deactivation.

[0100] Preferably, the plasma reactor itself does not contain a catalyst. In a particularly preferred embodiment, the plasma reactor does not contain a fixed-bed catalyst. In another preferred embodiment, the plasma reactor does not contain a catalyst. Plasma-based BRMs operate under high-energy conditions that promote the dissociation of methane, carbon dioxide, and water without a catalyst. A known limitation of catalytic BRMs is catalyst deactivation, which can occur due to carbon deposition (coking), sintering of active metal sites, or poisoning by sulfur or other contaminants. While the presence of water in the BRM helps mitigate coking by promoting the oxidation pathway that converts deposited carbon to CO and H2, catalyst deactivation remains a significant problem, leading to persistent fluctuations in the H2 / CO ratio of the resulting syngas. Such fluctuations have profound implications for downstream processes, particularly in methanol synthesis, where precise control of the syngas composition is crucial. Furthermore, while plasma-catalytic reactors hold significant potential for reaction enhancement, they are extremely difficult to operate in a continuous, stable, controlled, and scalable manner due to the complex interactions between the plasma-generated material and the catalyst surface.

[0101] More preferably, if a catalyst is used, it is placed downstream of the plasma reactor to optimize the composition of the syngas after plasma conversion. Even more preferably, the plasma and catalyst are contained separately to ensure a stable and controlled process, minimizing the risk of catalyst degradation caused by direct plasma exposure. This application aims to overcome the known problems of catalytic BRM by focusing on direct plasma BRM. This method eliminates the limitations associated with catalyst deactivation in the main conversion step, providing a more robust and stable approach for syngas production. The challenges associated with plasma-catalytic reactors can be partially mitigated by employing a two-stage system in which a catalytic reactor is connected in series after direct plasma BRM. In this configuration, the catalytic BRM reactor is primarily used to refine conversion efficiency and improve selectivity for the desired syngas composition. Furthermore, more preferably, a liquid trap is included between the plasma reactor and the catalytic reactor. This feature helps reduce catalyst deactivation by trapping condensate, heavy hydrocarbons, or other contaminants that could poison the catalyst. Advantageously, most of the BRM is carried out in a non-catalytic environment, which significantly extends catalyst lifetime and ensures a more stable and predictable syngas output.

[0102] In a preferred embodiment, the syngas produced in the plasma reforming step preferably comprises at least 90% by volume, more preferably at least 95% by volume, even more preferably at least 98% by volume, even more preferably at least 99.0% by volume, even more preferably at least 99.5% by volume, and most preferably up to 99.9% by volume of CH4, CO2, CO, H2, and H2O. More preferably, the syngas consists essentially of CH4, CO2, CO, H2, and H2O; even more preferably, it consists essentially of CO, H2, and H2O, thereby minimizing the presence of unreacted CH4 and CO2. In another preferred embodiment, the amount of byproducts (including heavier hydrocarbons and oxygen-containing compounds) is at most 2% by weight, more preferably at most 1% by weight, even more preferably at most 0.5% by weight, even more preferably at most 0.2% by weight, even more preferably at most 0.1% by weight, and most preferably at most 0.05% by weight. Reforming reactors typically produce byproducts such as higher hydrocarbons and oxygen-containing hydrocarbons. In the two-stage reactor setup of the present invention, these byproducts should be minimized as much as possible to prevent operational problems in downstream processing. In particular, the formation of hydrocarbons such as acetylene (C2H2) and ethylene (C2H4) should be avoided, as these compounds significantly promote coking and reactor fouling, leading to instability in the plasma reactor and subsequent Fischer-Tropsch (FT) or methanol reactors. Advantageously, the inventors have discovered that direct plasma BRM in sliding arc and glow discharge reactors can keep the total amount of hydrocarbons and unwanted byproducts below 1%, significantly reducing the risk of carbon deposition and increasing reactor life. The presence of water in the BRM further helps limit coke formation by promoting the oxidative pathway for removing deposited carbon. This low byproduct formation allows for seamless coupling with downstream FT or methanol reactors, ensuring stable operation and high syngas conversion efficiency. By carefully controlling plasma conditions and the water-to-carbon ratio, the present invention enables the production of clean, high-purity syngas compositions optimized for further processing while minimizing process inefficiencies associated with unwanted side reactions.

[0103] In step c) of the method, the resulting syngas is supplied to a Fischer-Tropsch reactor (FT reactor).

[0104] A Fischer-Tropsch reactor, or FT reactor, is a chemical reactor used for Fischer-Tropsch synthesis, the process of converting syngas (a mixture of carbon monoxide (CO) and hydrogen (H2)) into liquid hydrocarbons, ranging from light fuels such as gasoline to heavier waxy substances. This reactor is designed to promote catalytic reactions under controlled temperature and pressure conditions, optimizing the conversion of syngas into hydrocarbons.

[0105] In a particularly preferred embodiment, the FT reactor is a methanol reactor, such that the resulting syngas is supplied to the methanol reactor in step b), wherein the CO and H2 in the syngas are at least partially converted into methanol in the methanol reactor.

[0106] In a particularly preferred embodiment, the method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a methanol reactor, wherein the CO and H2 in the syngas are at least partially converted into methanol in the methanol reactor.

[0107] The FT reactor is designed to operate under conditions favorable to the conversion of syngas into desired fuel products, such as methanol. The temperature in the FT reactor is preferably from 150°C to 350°C, more preferably from 200°C to 300°C, and most preferably from 220°C to 300°C. The pressure in the methanol reactor can be from 20 to 200 bar, more preferably from 50 to 100 bar.

[0108] In another preferred embodiment, heat generated by the FT reactor is used to generate and sustain water vapor. The FT reactor may be equipped with a heat exchanger or water jacket that directly generates water vapor. This reduces costs by avoiding the use of heated pipelines and boilers. Alternatively, waste heat can also be recovered from the plasma reactor in an equivalent manner.

[0109] In a preferred embodiment, the method involves using H2O from a liquid water tank. In the current embodiment, the liquid water from this tank is converted into water vapor using heat recovered from the FT reactor. This embodiment offers a significant advantage in terms of energy efficiency because it reuses heat generated by the FT reactor that would otherwise be wasted to convert water into water vapor. This reduces the overall energy consumption of the process and contributes to a more sustainable and environmentally friendly methanol production method.

[0110] The use of heat recovered from the FT reactor in this conversion process eliminates the need for additional energy input, which would be required if water vapor were generated separately. This results in significant energy savings and improves the overall efficiency of the process.

[0111] In a preferred embodiment, heat recovered from the methanol reactor is transferred to water in a tank, raising its temperature and vaporizing it into water vapor. The water vapor is then introduced into a plasma reactor, where it participates in a double reforming reaction.

[0112] In another preferred embodiment, the liquid water tank is connected to the methanol reactor via a heat exchanger or a similar device that facilitates heat transfer from the reactor to the water. The heat exchanger can be designed to maximize heat transfer efficiency and minimize heat loss to the environment. This further contributes to the energy efficiency of the system and the overall sustainability of the methanol production process.

[0113] This invention specifically relates to a two-step process for methanol production, wherein the first step comprises plasma double reforming (BRM) of methane to produce syngas comprising CO, H2, and H2O; and the second step comprises feeding the syngas into a separate Fischer-Tropsch reactor (preferably a methanol reactor) to convert the syngas into methanol. This dual-reactor setup offers significant advantages over a single-reactor configuration, particularly in terms of process flexibility, efficiency, and product separation.

[0114] A key advantage of this two-step approach is the ability to independently optimize the operating conditions of each reactor. Plasma double reforming of methane is most efficient at or near atmospheric pressure, as higher pressures disrupt plasma formation and reduce conversion efficiency. In contrast, the methanol reactor operates optimally at elevated pressures (preferably above 50 bar) to enhance methanol synthesis kinetics and improve single-pass conversion. By maintaining separate reactors, each stage can be individually fine-tuned for maximum efficiency without compromising the conditions required for the other step. Furthermore, the inclusion of water in the double reforming step allows for greater flexibility in adjusting the H2 / CO ratio, thereby further optimizing the syngas composition to suit downstream methanol production requirements.

[0115] Another key benefit is the improved ability to separate and recycle unreacted gases. The methanol reactor produces both liquid methanol and a gaseous fraction containing unreacted CO, H2, and byproducts such as CO2 and H2O. In this invention, the methanol reactor output can be effectively separated into liquid and gas phases, allowing the gaseous fraction to be recycled back to the methanol reactor for further improved conversion efficiency. This gas recirculation is not feasible in a single-reactor setup because plasma dual integration and methanol synthesis would occur in the same environment, leading to low reactant utilization and product dilution.

[0116] Furthermore, separating the plasma dual-stage integration step from the methanol synthesis step provides greater operational stability and scalability. The dual-reactor system allows for better control of the syngas composition and reduces H2 / CO ratio fluctuations that can negatively impact methanol yield. Moreover, by decoupling the two stages, each reactor can be designed with materials and configurations best suited to its respective reaction conditions, thereby extending reactor life and reducing maintenance requirements. The presence of water in the BRM further helps limit carbon deposition, reducing fouling in both reactors and enhancing long-term system stability. This modular approach ultimately improves process efficiency, enhances methanol yield, and provides a more robust and scalable pathway for sustainable methanol production.

[0117] In another or further preferred embodiment, the method incorporates a recovery step in which water is recovered from the fuel production process itself and reused for dual reforming in the biogas reactor. This preferred embodiment of the method (which incorporates the recovery and reuse of water from the methanol production process for biogas dual reforming) represents a significant advancement in the field of sustainable chemical processing. This method not only improves process efficiency but also helps conserve water resources and reduce operating costs. In another preferred embodiment, the system optionally includes a liquid trap or separator fluidly connected between the plasma dual reforming (BRM) reactor and the methanol reactor. More preferably, the syngas passes through the plasma reactor to the methanol reactor, while a small liquid fraction is separated. Such a separation stage is incorporated before introducing the syngas into the methanol reactor to remove liquid components and solid impurities. Preferably, the liquid trap or separator is configured to separate condensate, unreacted hydrocarbons, and any entrained particulate matter that may form during plasma dual reforming. More preferably, the separator is designed to operate passively, relying on phase behavior differences rather than requiring additional energy-intensive separation processes.

[0118] Advantageously, this intermediate separation step reduces the accumulation of liquid and solid impurities within the methanol production loop, thereby limiting the accumulation of undesirable byproducts that would otherwise require complex downstream purification. While BRM inherently contains water during reforming, excess liquid water can negatively impact methanol synthesis conditions. By removing excess condensate before the syngas enters the methanol reactor, this implementation ensures the H2 / CO ratio remains within the preferred range for methanol synthesis while preventing reactor condition fluctuations that could lead to catalyst deactivation. Furthermore, separating any entrained hydrocarbons or solid impurities reduces reactor fouling, extends catalyst lifetime, and minimizes the risk of deactivation associated with coke or heavy hydrocarbon deposition.

[0119] These benefits can be achieved without a comprehensive gas purification stage, thus avoiding the high energy costs typically associated with conventional gas-liquid separation units. Therefore, introducing a liquid trap or separator provides an efficient, low-energy solution for maintaining reactor performance, ensuring process stability, and improving overall methanol production efficiency in BRM-based systems.

[0120] In a preferred embodiment, the FT reactor (more preferably a methanol reactor) is a fixed-bed catalytic reactor configured for hydrogenating carbon monoxide and carbon dioxide to methanol. The reactor preferably includes a reaction chamber containing a heterogeneous catalyst, wherein the catalyst is preferably selected from copper-based catalysts, more preferably Cu / ZnO / Al₂O₃, and even more preferably modified Cu / ZnO-based catalysts with enhanced thermal stability and resistance to deactivation. The methanol reactor is preferably designed to operate at elevated pressures to optimize conversion efficiency and maintain catalyst performance over extended operating periods.

[0121] In a preferred embodiment, the methanol reactor is operated at a pressure of at least 50 bar, more preferably at least 70 bar, even more preferably at least 80 bar, even more preferably at least 90 bar, and most preferably 90 to 100 bar. Operating at high pressure increases the conversion of syngas to methanol by shifting the reaction equilibrium towards methanol synthesis, thereby improving single-pass efficiency. In another preferred embodiment, the methanol reactor is operated at a temperature of at least 150°C, more preferably at least 180°C, even more preferably at least 200°C, even more preferably at least 220°C, and most preferably 220 to 280°C. These temperatures ensure optimal catalytic activity while minimizing undesirable side reactions (e.g., excess water formation or catalyst sintering).

[0122] In a second aspect, the present invention can be described as a method for optimizing syngas. In this document, the embodiments of steps a) and b) as described above correspond to embodiments of this method.

[0123] The method includes the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O, and CH4; and b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2.

[0124] In a particularly preferred embodiment, the one or more gaseous input streams contain at least 40% by volume of H2O.

[0125] The volume ratio of CO to H2 in the synthesis gas is preferably 1.5 to 2.5.

[0126] The invention will now be described in more detail with reference to non-limiting embodiments.

[0127] Embodiments and accompanying drawings

[0128] To better illustrate the features of the invention, several preferred applications based on the invention for inspecting the condition of slurry used in mechanical connections are described below by way of example (in no way limiting its potential applications), wherein: Figure 1 An embodiment of the present invention is illustrated.

[0129] Water vapor, methane, and carbon dioxide are supplied to plasma reactor 101, where methane double reforming is carried out according to reaction (C) to obtain syngas 102 containing CO and H2.

[0130] (C)

[0131] When the resulting syngas is preferably used to produce methanol according to reaction (D), the optimal molar ratio of CO to H2 in the syngas is 1:2.

[0132] (D)

[0133] Reaction (D) indicates that a CO to H2 molar ratio of 1:2 is the optimal mixture for methanol synthesis. Reaction (B) indicates that a molar ratio of methane, water vapor (gas phase), and carbon dioxide of 3:2:1 should be used to achieve a CO to H2 molar ratio of 1:2.

[0134] However, the inventors have discovered that a stoichiometric ratio of 3:2:1 (16.6% CO2 - 50% CH4 - 33.3% H2O) leads to excessive soot generation.

[0135] Materials and Methods

[0136] CH4 and CO2 (both 99.9% by volume) were purchased from Air Liquide, and the flow rates of both gases were regulated using a Bronkhorst thermal mass flow controller. Both gases were mixed with deionized water before entering the plasma reactor. The H2O container was heated via a silicone oil bath placed above a heated plate stirrer (IKA RCT basic). The precise flow rate of the H2O vapor (and its input ratio) was regulated by maintaining the oil bath at a specific temperature. The calculation of the H2O vapor flow rate (in mol / min) is provided in Section S1. For each selected oil bath and H2O vapor temperature, the stainless steel gas line between the H2O container and the reactor inlet was heated to approximately 10°C above the oil bath temperature to prevent H2O condensation and to introduce a homogeneous CO2-CH4-H2O gas mixture into the plasma. This is why we refer to the H2O input as “vapor” rather than “steam”: no heterogeneous H2O droplets enter the plasma reactor. The output gas mixture is introduced into a cold trap and carbon filter before entering a heated sample gas line connected to an Agilent dual-channel 990 MicroGC for analyzing the dried gas mixture.

[0137] 1. Ash generation and plasma stability

[0138] Table 1 clearly shows that under the current conditions, a significant amount of soot generation occurs when the CH4 fraction exceeds approximately 42% by volume (Comparative Example 1, Examples 4, 5, 8, and 9). However, the specific energy input (SEI, i.e., power divided by the total input flow rate) also has an effect. Specifically, we also tested the 14-41-45 (CO2-CH4-H2O) mixture at the same total input flow rate (3 Ls / min) but with a higher plasma power (400 W instead of 300 W). Under these conditions, the plasma was significantly more stable.

[0139] Table 1

[0140] At the same CH4 input fraction, we also observed that stability varied with the CO2:H2O ratio. For example, both mixtures in Table 1 had 36 vol% CH4, but the mixture with only 19 vol% CO2 and 45 vol% H2O (Example 12) was significantly more stable (no soot was observed on the reactor wall, and plasma power was stable at constant current and inter-electrode distance), while in the mixture with 36 vol% CO2 and only 28 vol% H2O (Example 3), soot formation (and its effect on plasma power) was clearly visible. Therefore, this is highly advantageous compared to DRM (where the CH4 fraction is >35 vol%), in which soot formation is suppressed only under very specific conditions (e.g., below atmospheric pressure and reverse eddy current dynamics).

[0141] 2. Effect of CO2:CH4 ratio

[0142] refer to Figure 7 The conversion and yield (%) of reactants and products, and the conversion and formation rate (mmol / min), are shown as functions of the CO2:CH4 input ratio at a 45% volume H2O input fraction. X H Y The combined yield and formation rate of the detected small molecule hydrocarbons, which consist of (in descending order) C2H2, C2H4, C2H6 and C3H8 (i.e., n-propane).

[0143] In terms of yield and production rate, CO showed a clear decreasing trend, while H2 showed an increasing trend. This can obviously be explained by the higher conversion rates of CH4 and H2O and the lower conversion rate of CO2. Therefore, the syngas ratio (SR, H2 / CO) increased to 2.03 (see [link to syngas analysis]). Figure 6 b) This exceeds twice the value when the CO2:CH4 input ratio is 1.86, achieving the desired target for further downstream production of high-value-added oxygenated compounds (such as methanol).

[0144] Clearly, shifting the CO2:CH4 ratio towards a higher CH4 content is advantageous. At the highest CH4 fraction, almost all performance parameters (except CO2 conversion) are optimal, and the most important objectives (i.e., SR of 2 and energy consumption below 412 kJ / mol) are achieved. The ideal stoichiometric BRM reaction requires an input CO2-CH4-H2O mixture of 1–3–2, while our optimal results were obtained at a ratio of 1–2.9–3.2. However, reducing the H2O content from 45 vol% to 33 vol% (as required by the optimal stoichiometry) compromises plasma stability due to excessive soot generation (see Table 1: conditions shown in red).

[0145] Table 2 shows that a higher SEI significantly improved conversion and product yield, while SR, EC, and EE only slightly decreased. However, an SR of 1.94 is still sufficiently high for further methanol synthesis.

[0146] Table 2

[0147] Compared to pure DRM, the addition of H2O helps to counteract soot formation, resulting in more stable plasma conditions. A mixture of 14–41–45 vol% (CO2-CH4-H2O) yielded the best overall results in terms of plasma stability and performance parameters. Specifically, at an SEI of 210 kJ / mol, we achieved CO2 and CH4 conversions of 49% and 74% (based on converted reactants), respectively, at an EC of 390 kJ / mol, which is below the targets defined to make plasma-based syngas production competitive with other technologies. Furthermore, we achieved CO and H2 yields of 59% and 49%, respectively, and a SR of 2, which is ideal for further methanol synthesis.

[0148] In a specific embodiment of the present invention, such as Figure 2 As shown, the incoming gaseous input stream is a biogas input stream. Biogas typically contains methane, carbon dioxide, and water. Exemplary biogas mixtures are shown in Table 3.

[0149] Table 3

[0150] Typically, in existing technologies, biogas is purified through a separation stage (e.g., distillation or pressure swing adsorption). This removes undesirable products such as CO2 and H2O. This method increases cost because the separation process can be energy-intensive. Furthermore, CO2 gas is emitted, which is undesirable. While CO2 gas can be captured, this further increases the price of the CH4 product.

[0151] The inventors have now found a solution to this problem by omitting the separation stage and replacing it with a plasma reactor, such as... Figure 2 As shown, the plasma reactor promotes the dry reforming and steam reforming of methane, also known as the methane dual reforming according to reaction (1). Figure 2 A biogas input stream 203 containing methane, carbon dioxide, and water is shown being supplied to a plasma reactor 201. The resulting output gas mixture is a syngas 202 containing H2 and CO. The proportion of these products in the syngas is preferably about 2.

[0152] The plasma reactor is preferably an atmospheric pressure reactor, which raises the gas temperature to 3000K-5000K, more preferably 2500K-3500K, and even more preferably 2600K. The advantages of the plasma system lie in the complete electrification of the process and the direct heating of the gas.

[0153] Further preferred embodiments of the present invention are shown in Figure 3 The inventors have found that, although biogas typically contains water, the addition of another water source is beneficial. Typically, biogas contains 0-10% by volume of water; however, the inventors have found that higher amounts are preferred. Preferably, the gaseous input stream contains 30 to 50% by volume of water, more preferably 35 to 50% by volume, and most preferably about 45% by volume. The water can be introduced into the plasma reactor 301 in the form of steam from a water tank or equivalent water source 304. The water can be maintained in steam form via a heated conduit 305, which can be constructed on a resistance heating wire. Dry steam (>100°C, water vapor) is preferred for operation, but wet steam (about 100°C) can also be used. Biogas 303 is simultaneously supplied to the plasma reactor 301, where syngas 302 comprising H2 and CO is formed. The proportion of these products in the syngas is preferably about 2. In another preferred embodiment, the water source 304 can be a chemical process that generates waste steam.

[0154] In even a more preferred embodiment of the invention, the synthesis gas stream can be directly converted into fuel or olefins 407 via a Fischer-Tropsch reactor 406. This is shown in Figure 4 In this context, numbers 401 to 405 correspond to numbers 301 to 305. Methanol (MeOH) production is particularly attractive to the chemical and shipping industries.

[0155] Furthermore, the complete use of biogas to produce fuel via electrified reactors opens up the possibility of designating the product as either biofuel or e-fuel. This offers a significant advantage in terms of market adaptability within the context of fossil fuel emission reduction efforts.

[0156] In another or further preferred embodiment of the invention, such as Figure 5 As shown, the heat generated by the FT reactor 506 can be used to generate and sustain steam. The FT reactor 506 can be equipped with a heat exchanger or water jacket 509 that directly generates steam. Water can be supplied cold 508, heated 509, and supplied to the plasma reactor via heated piping 505. In this way, the use of a boiler is avoided, thereby reducing another cost. Figure 5 In this context, numbers 501 to 504 and 507 correspond to numbers 401 to 404 and 407. Alternatively, waste heat can also be recovered from the plasma reactor in an equivalent manner.

[0157] In another or further preferred embodiment of the invention, water can be extracted from the FT reactor 606 itself. Water is a known byproduct of the FT process and typically contains trace amounts of hydrocarbons. Typically, water is separated from the hydrocarbon components by distillation column 610 and heated via heat exchanger 611 using heat from the FT reactor 606. This... Figure 6 An example is shown in the image. This implementation is particularly useful in water-scarce areas. Figure 6 In the text, the numbers 601 through 603, 607, and 609 correspond to the numbers 501 through 503, 507, and 509.

[0158] This invention is by no means limited to the embodiments described and / or shown in the figures. Rather, the method according to the invention can be implemented in many different ways without departing from the scope of the invention.

Claims

1. A method for producing methanol, wherein the method comprises the following steps: a. Supplying one or more gaseous input streams to the plasma reactor, wherein the one or more gaseous input streams contain at least CO2, H2O and CH4; b. Ignite the plasma in the plasma reactor, thereby causing the CO2, H2O and CH4 to react and form a synthesis gas containing CO and H2; c. The syngas is supplied to a methanol reactor, wherein the CO and H2 in the syngas are at least partially converted into methanol in the methanol reactor. The feature is that the one or more gaseous input streams contain at least 40% by volume of H2O.

2. The method for methanol production as claimed in claim 1, wherein the specific energy input of the plasma reactor is at least 150 kJ / mol, preferably at least 200 kJ / mol.

3. The method for methanol production as claimed in any of the preceding claims, wherein the volume ratio of the total amount of CH4 to the total amount of CO2 contained in the one or more gaseous input streams is at least 2, preferably at least 3.

4. The method for methanol production as claimed in any of the preceding claims, wherein the volume ratio of the total amount of H2O contained in the one or more gaseous input streams to the total amount of CO2 and CH4 is at least 0.4, preferably at least 0.

8.

5. The method for methanol production as claimed in any of the preceding claims, wherein the volume ratio of the total amount of CO2, the total amount of CH4, and the total amount of H2O contained in the one or more gaseous input streams is 0.9-1.1:2.8-3.0:3.1-3.

3.

6. The method for methanol production as described in any of the preceding claims, wherein the plasma reactor is an atmospheric pressure glow discharge plasma reactor.

7. The method for methanol production as claimed in any of the preceding claims, wherein the plasma reactor operates at a power level of 300 W to 500 MW.

8. The method for methanol production as claimed in any of the preceding claims, wherein the volume ratio of H2 to CO in the synthesis gas is 1.9 to 2.

1.

9. The method for methanol production as claimed in claim 1, wherein the volume ratio of the total amount of CO2, CH4 and H2O contained in the one or more gaseous input streams is 0.9-1.1:2.8-3.0:3.1-3.3, wherein the specific energy input of the plasma reactor is at least 200 kJ / mol, and wherein the plasma reactor is an atmospheric pressure glow discharge plasma reactor.

10. The method for methanol production as claimed in any of the preceding claims, wherein a gaseous input stream is supplied in step a, and wherein the gaseous input stream is biogas.

11. The method for methanol production as claimed in any of the preceding claims, wherein in step a, two or more gaseous input streams are supplied, one of which is biogas and the other is pure CO2 or pure H2O.

12. The method for methanol production as claimed in any of the preceding claims, wherein in step a, two or more gaseous input streams are supplied, one of which is biogas and the other is pure H2O.

13. The method for methanol production as claimed in claim 12, wherein the H2O is derived from a liquid water tank, wherein the liquid water is converted into water vapor using heat recovered from the methanol reactor.

14. The method for methanol production as claimed in claim 12, wherein the H2O is derived from a liquid water tank, wherein the liquid water is converted into water vapor using heat recovered from the plasma reactor.

15. The method for methanol production as described in claim 12, wherein the H2O is recovered from the methanol production process.

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