WO2025196271A1

WO2025196271A1 - Method for methanol production

Info

Publication number: WO2025196271A1
Application number: PCT/EP2025/057803
Authority: WO
Inventors: Annemie BOGAERTS; Georgi TRENCHEV
Original assignee: Universiteit Antwerpen
Current assignee: Universiteit Antwerpen
Priority date: 2024-03-21
Filing date: 2025-03-21
Publication date: 2025-09-25
Anticipated expiration: 2026-09-21

Abstract

The current 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 and CH4, b) igniting a plasma in the plasma reactor, thereby dry reforming said CH4 to form a syngas comprising CO and H2, c) supplying said syngas to a methanol reactor, wherein said CO and H2 in the syngas are at least partially converted to a liquid phase comprising at least methanol, wherein said plasma outlet and said methanol reactor inlet are fluidly connected, and in that said gaseous input streams comprise a total amount of CH4 and a total amount of CO2 in a volume ratio of at least 2.

Description

METHOD FOR METHANOL PRODUCTION

FIELD OF THE INVENTION

The present invention relates to a method for optimizing syngas for use in methanol production.

BACKGROUND

Methanol, also known as methyl alcohol (CH3OH or MeOH), is a widely utilized commodity chemical with diverse applications across various industries. Its lightweight and flammable nature make it suitable for applications ranging from industrial processes to being considered an alternative fuel for combustion engines.

In recent years, the escalating levels of greenhouse gases, such as carbon dioxide (CO2) and hydrogen carrier (methane), have become significant environmental concerns. The heightened awareness of climate change and the potential release of frozen hydrogen carrier deposits in the Arctic have accentuated the need for innovative solutions to mitigate the impact of these potent greenhouse gases on the environment. Notably, methane is approximately ten times more potent as a greenhouse gas than carbon dioxide.

The conventional methods of addressing greenhouse gas emissions often involve separate capture and conversion processes, leading to increased complexity, energy consumption, and costs. Consequently, there is a demand for an integrated and efficient system capable of simultaneously capturing, separating, and converting a mixture of CO2 and a hydrogen carrier into a valuable and environmentally friendly end product.

The present invention targets at solving at least one of the aforementioned disadvantages.

SUMMARY OF THE INVENTION

The present invention and embodiments thereof serve to provide a solution to one or more of above-mentioned disadvantages. To this end, the present invention relates to a method according to claim 1. Preferred embodiments of the method are shown in any of the claims 2 to 11. In a second aspect, the present invention relates to a system according to claim 12.

Preferred embodiments of the system are shown in any of the claims 11 to 15.

The direct fluid connection between the plasma reactor outlet and the methanol reactor inlet in this system offers significant benefits for the conversion process of greenhouse gases into methanol. This configuration ensures a seamless and continuous flow of the synthesized gas (syngas) from the plasma reactor, where CO2 and a hydrogen carrier are converted into a mixture of H2, and CO, directly into the methanol reactor for immediate conversion into methanol. This direct linkage minimizes the exposure of the syngas to atmospheric contaminants and reduces the risk of gas composition changes between stages, which can occur due to cooling or interaction with external environments. It enhances the efficiency of the overall process by maintaining optimal temperatures and pressure conditions conducive to the chemical reactions involved, thereby increasing the yield and purity of the methanol produced. Furthermore, it simplifies the system design, reducing the need for additional piping, valves, and intermediate storage, which, in turn, lowers capital and operational costs. The integration of these reactors into a single, streamlined process flow leverages the high reactivity and energy efficiency of plasma-assisted conversion, leading to a more compact, efficient, and environmentally friendly methanol production system.

In a third aspect the present invention relates to a use according to claim 15.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

As used herein, the following terms have the following meanings:

"A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment. "About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/- 20% or less, preferably +/-10% or less, more preferably +/-5% or less, even more preferably +/-1% or less, and still more preferably +/-0.1% or less of and from the specified value, in so far such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

"Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

The expression "% by weight", "weight percent", "%wt" or "wt%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the teaching of the present invention. The terms or definitions used herein are provided solely to aid in the understanding of the invention.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

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

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 CO? and a hydrogen source, and b. igniting a plasma in the plasma reactor, thereby allowing the CO2 and the hydrogen source to react and form syngas comprising CO and H₂.

The ignition of the plasma in the plasma reactor allows the CO2 and hydrogen source to react and form syngas. The conversion of CO2 and the hydrogen source in a plasma reactor results in a syngas with CO and H₂ according to reaction (A).

CH₄ + co₂ -► 2CO + 2H₂

The expression "hydrogen source" as used herein refers to any molecule that can release hydrogen atoms under specific conditions (here, in a plasma reactor) to participate in a chemical reaction, specifically for the purpose of producing syngas from CO2. In a preferred embodiment said hydrogen source is a hydrocarbon chosen from the list of: methane, ethane, propane, butane ..., preferably methane (CH₄). If the hydrogen source is methane, a dry reforming of methane (B) takes place in the plasma reactor.

In a particularly preferred embodiment, 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 CO? and CH₄, and b. igniting a plasma in the plasma reactor, thereby dry reforming the CH₄ and form syngas comprising CO and H₂.

The syngas obtained from this method has been proven to be ideal for hydrocarbon production, preferably methanol production. It is therefore that in a further preferred embodiment, the method comprises the step of c) supplying said syngas to a Fischer-Tropsch reactor, preferably a methanol reactor.

In a particularly preferred embodiment, 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 and hydrogen source, preferably CH₄, b. igniting a plasma in the plasma reactor, thereby allowing the CO2 and hydrogen source, preferably CH₄, to react and form syngas comprising CO and H₂, c. supplying said syngas to a Fischer-Tropsch reactor, preferably a methanol reactor.

The ignition of the plasma in the plasma reactor allows the CO2 and CH₄ to react and form syngas. The conversion of CO2 and CH₄ (dry reforming of methane) in a plasma reactor results in a syngas with CO and H₂ according to reaction (B).

CH₄ + co₂ -► 2CO + 2H₂ (B)

When the resulting syngas is preferentially used for the production of methanol according to reaction (C), a molar ratio of CO and H₂ of 1 :2 in the syngas is optimal. co + 2H₂ -► CH₃OH (C) Reaction (C) shows that a molar ratio of CO and H₂ of 1:2 is the optimal mixture for methanol synthesis.

The inventors have found that the gaseous input streams comprise advantageously a total amount of CH₄ and a total amount of CO₂ in a volume ratio of at least 2.

Controlling the input hydrogen source fraction offers high-sensitivity, rough control.

This particular ratio is significant as it optimizes the formation of syngas, thus enhancing the subsequent production of methanol. The syngas, in this case, is an advantageous mixture for methanol synthesis, due to the volume ratio of H₂ and CO approaching 2 without soot formation, which is an ideal condition for the production of methanol. The method, therefore, presents an innovative approach to the production of methanol, utilizing a plasma reactor and a specific ratio of gaseous inputs to optimize the process.

The system facilitates the direct and instant conversion of primary inputs, namely CO₂ and CH₄, into syngas. This omits any requirement for prior steps or temporary storage, boosting the efficiency of the process and uninterrupted flow in the entire procedure. The performance benefits have been seen to surpass those achieved with stoichiometric ratios, translating into an enhanced, flexible and environmentally friendly alternative to traditional gas reforming methods.

In a preferred embodiment, said one or more gaseous input streams comprise a total amount of CH₄ of at least 20 vol%, preferably at least 30 vol%, more preferably at least 40 vol%, even more preferably at least 50 vol%, even more preferably at least 60 vol%, even more preferably at least 65 vol%.

In a preferred embodiment, said one or more gaseous input streams comprise a total amount of CH₄ of between 20 and 80 vol%, preferably between 30 and 80 vol%, more preferably between 40 and 80 vol%, even more preferably of between 50 and 80 vol%, even more preferably between 60 and 80 vol%, even more preferably between 65 and 80 vol%.

In a preferred embodiment, said one or more gaseous input streams comprise a total amount of CO₂ of at most 60 vol%, preferably at most 50 vol%, more preferably at most 40 vol%, even more preferably at most 35 vol%. In a preferred embodiment, said one or more gaseous input streams comprise a total amount of CO? of between 20 and 60 vol%, preferably between 20 and 50 vol%, more preferably between 20 and 40 vol%, even more preferably of between 20 and 35 vol%, even more preferably between 20 and 35 vol%.

In a preferred embodiment, said one or more gaseous input streams comprise a total amount of water of at most 20 vol%, preferably at most 10 vol%, more preferably at most 5 vol%, even more preferably at most 2 vol%, even more preferably at most 1 vol%, even more preferably at most 0.5 vol%. Most preferably, the gaseous input stream is substantially free of water. Controlling the water content in the gaseous input stream is particularly advantageous in the context of dry reforming of methane (DRM), as excessive water can interfere with the reaction kinetics and promote unwanted side reactions and altering the desired H2 to CO ratio. Maintaining a low water content ensures that the DRM reaction proceeds efficiently, enhancing syngas quality and optimizing the production of methanol or other hydrocarbons downstream. Moreover, a lower water content reduces the risk of catalyst deactivation and minimizes the need for additional separation steps, thereby improving the overall process efficiency.

In an alternative embodiment, the one or more gaseous input streams may comprise a controlled amount of water, preferably at least 0.01 vol%, more preferably at least 0.05 vol%, even more preferably at least 0.1 vol%, even more preferably at least 1 vol%, and most preferably between 0.1 vol% and 10 vol%. The presence of a controlled amount of water in the gaseous input stream can be beneficial in mitigating the formation of solid carbon (soot), which is a known challenge in dry reforming of methane. Water in the input stream promotes oxidation pathways that help suppress carbon deposition on reactor surfaces and within the plasma zone, preventing catalyst deactivation and reactor fouling. Even minimal amounts of solid carbon can have a disproportionately negative impact on plasma stability, as carbon particulates may accumulate within the plasma reactor, altering the electrical conductivity of the discharge and leading to localized disruptions in the plasma field. Such instability can reduce conversion efficiency, increase energy consumption, and ultimately necessitate more frequent reactor maintenance.

In a preferred embodiment, said one or more gaseous input streams comprise a total amount of water of at most 1 vol%, preferably at most 0.5 vol%, more preferably at most 0.1 vol%, even more preferably at most 1000 ppm, even more preferably at most 500 ppm, and most preferably at most 100 ppm. Maintaining an extremely low water content in the gaseous input stream is particularly advantageous in the context of direct-plasma methane reforming, including dry reforming of methane (DRM), as even trace amounts of water can significantly influence reaction pathways.

An increase in water content leads to a higher concentration of OH radicals in the plasma, which promotes H2O formation pathways at the expense of H2 production and facilitates recombination with CO, thereby reducing CO yield. As a result, increasing concentrations of OH radicals directly decrease syngas production efficiency, lowering both H2 and CO yields in plasma-driven reforming processes. While these effects can be mitigated by the use of catalysts that selectively drive the desired reaction pathways, catalytic systems introduce additional challenges, including coking, sintering, and deactivation over time. By ensuring an ultra-low water content in the gaseous input stream, the present method advantageously maximizes syngas yield, preserves long-term reactor stability, and reduces the need for complex catalyst regeneration or additional purification steps.

It is clear that the inclusion of water in the gaseous input stream introduces a tradeoff in direct-plasma methane reforming. On the one hand, water plays a beneficial role in suppressing solid carbon formation, thereby mitigating issues such as plasma instability, reactor fouling, and electrode degradation. Additionally, the presence of water shifts the H2/CO ratio upwards, which can be advantageous for downstream applications such as methanol synthesis, where a higher hydrogen content is often preferred. However, these benefits come at a significant cost. Increased water content leads to a higher concentration of OH radicals in the plasma, which promotes recombination pathways that reduce the yields of both H2 and CO. This shift in reaction pathways decreases overall syngas production efficiency, as more energy is consumed in forming H2O rather than driving the desired dissociation of CH4 and CO2. Consequently, while water can improve process stability and selectivity under certain conditions, excessive amounts severely compromise yield and energy efficiency. Achieving the optimal balance between these competing effects is critical in optimizing direct-plasma DRM, ensuring that carbon suppression benefits are realized without sacrificing overall process performance.

In an alternative embodiment, the one or more gaseous input streams may further comprise oxygen, preferably at least 0.01 vol%, more preferably at least 0.1 vol%, even more preferably at least 1 vol%, more preferably at least 3 vol%, more preferably at least 5 vol%, more preferably at least 7 vol, more preferably at least 10 vol%, most preferably between 0.1 vol% and 10.0 vol%. In a further embodiment, the one or more gaseous input streams may further comprise oxygen in an amount of at most 30 vol%, preferably at most 20 vol%, more preferably at most 15 vol%, even more preferably at most 10 vol%, even more preferably at most 7 vol%, and most preferably at most 5 vol%. This controlled addition of oxygen facilitates oxy-reforming of methane, a process that integrates dry reforming (DRM) and partial oxidation (POM), improving syngas production efficiency while reducing carbon deposition. Oxy-reforming of methane involves the reaction of methane with both CO2 and O2, leading to the formation of CO and H2 through complementary reaction pathways. The presence of oxygen promotes partial oxidation of methane, which provides additional heat to sustain endothermic dry reforming reactions, thereby enhancing overall energy efficiency. Moreover, oxygen plays a crucial role in limiting the formation of solid carbon (soot), as it enables oxidation reactions that convert carbon deposits into CO and CO2, reducing reactor fouling and plasma instability. However, excessive oxygen leads to undesirable full oxidation of methane, producing CO2 and H2O instead of the desired syngas components.

In a preferred embodiment, the CO2 is captured in the form of adsorption, cryogenic distillation membranes or chemical looping.

Utilizing CO2 captured from these origins (adsorption, cryogenic distillation, membranes, or chemical looping) in the methanol production process presents a synergy of environmental and economic benefits. This approach leverages CO2, a potent greenhouse gas, as a raw material, effectively turning an environmental liability into a valuable feedstock. By integrating CO2 capture and utilization directly into methanol production, this strategy not only reduces the carbon footprint of industrial and agricultural processes but also enhances the overall efficiency and sustainability of methanol manufacturing. It aligns with circular economy principles by recycling carbon emissions back into useful products, thereby mitigating climate change impacts while meeting the growing demand for methanol as a fuel and industrial chemical. This integration also opens pathways for industries to achieve carbon neutrality or negativity by valorizing emissions that would otherwise contribute to atmospheric CO2 levels, making it a beneficial addition to current methanol production methodologies.

In a preferred embodiment, the hydrogen source is chosen from the list of: fossil fuel, biogas, synthesis gas, or gas mixtures from CO2 hydrogenation. Selecting a hydrogen source from fossil fuels, biogas, synthesis gas, or gas mixtures from CO? hydrogenation for methanol production significantly enhances the environmental profile of the process. By incorporating renewable and low-carbon hydrogen sources such as biogas and synthesis gas, the method reduces reliance on fossil fuels and decreases greenhouse gas emissions. Biogas, for instance, utilizes organic waste, turning it into a valuable resource, thereby contributing to waste reduction and promoting sustainability. Synthesis gas can be produced from renewable energy sources, further lowering the carbon footprint of the methanol production process. Additionally, using gas mixtures from CO2 hydrogenation not only utilizes CO2 as a raw material, preventing its release into the atmosphere, but also promotes carbon recycling. This approach directly aligns with global environmental goals by offering a cleaner, more sustainable pathway for methanol production, emphasizing the reduction of carbon emissions and the efficient use of resources in industrial processes.

In a particularly preferred embodiment, one gaseous input stream is supplied to the plasma reactor, wherein said gaseous input stream is biogas. In this embodiment, the methane and carbon dioxide are all present in said biogas and supplied to the plasma reactor.

The biogas input stream is a renewable energy source, typically produced from raw materials such as bio waste, manure, municipal waste, sewage, green waste, etc. This biogas is produced through a process of anaerobic digestion by microorganisms inside a bio chamber or a bio-reactor. The resulting gas composition is a mixture of primarily CH₄, CO2, and traces of H₂O, H₂S, and H₂. Within this preferred embodiment, the biogas used may vary in its composition, but typically consists of a mixture of primarily CH₄, CO2, with traces of H₂O.

Typically, the gas mixture is purified by a separation stage, such as a distillation stage or a pressure-swing adsorption stage. In this way, the undesirable products such as CO2 and H₂O are removed. This solution adds costs, as the separation process can be energy intensive. Moreover, CO2 gas is discharged, which is undesirable. The CO2 gas can be captured, but this will further increase the price of the CH₄ product.

The inventors have now found a method that resolves this problem by skipping the separation stage and replacing it with a specific plasma reactor, which facilitates dry reforming. In this preferred embodiment, the method is thus characterized by the supply of a single gaseous input stream in step a, which is specifically a biogas. This embodiment is particularly advantageous in terms of efficiency and resource optimization. The invention allows for the direct utilization of biogas, thereby improving the overall efficiency of the process. It bypasses the need for biogas upgrading steps, which typically require significant energy input and add to the production costs. By eliminating these steps, the invention not only saves energy but also reduces the overall cost of methanol production.

Furthermore, the invention turns waste biogas into valuable methanol, leading to greater resource optimization. Biogas, which is typically composed of methane, carbon dioxide, and traces of water, hydrogen sulfide, and hydrogen, is often considered a waste product. However, with this invention, such a waste product is transformed into a valuable chemical compound, methanol, which has numerous industrial applications. This not only adds value to the biogas but also contributes to waste reduction and promotes a circular economy.

It is to be understood that in this specific embodiment, wherein a single gaseous input stream in step a, which is specifically a biogas, is supplied to the plasma reactor, the above mentioned ratios and compositions of the one or more gaseous input streams apply equally. For example, "wherein said gaseous input streams comprise a total amount of CH₄ and a total amount of CO? in a volume ratio of at least 2" would be equal to "wherein said biogas comprises a total amount CH₄ and a total amount of CO2 in a volume ratio of at least 2".

In a particularly preferred embodiment, the method comprises the steps of: a. supplying a gaseous input stream to a plasma reactor, wherein the gaseous input stream is a biogas, and wherein the gaseous input stream comprises at least CO2 and CH₄, b. igniting a plasma in the plasma reactor, thereby dry reforming the CH₄ to form syngas comprising CO and H₂, c. supplying said syngas to a Fischer-Tropsch reactor, preferably a methanol reactor, wherein said biogas comprises a total amount of CH₄ and a total amount of CO2 in a volume ratio of at least 2. In a preferred embodiment, the biogas is produced from food waste, sewage sludge, agricultural waste, animal manure, or aquatic biomass.

Food Waste: Food scraps and waste from households, restaurants, and food processing industries often have high moisture levels. When anaerobically digested, the resulting biogas can contain significant amounts of water vapor.

Sewage Sludge: The anaerobic digestion of sewage sludge, which is the semi-solid material that remains after sewage treatment, can also produce biogas with a high water content. This is because sewage sludge typically contains a high percentage of water.

- Agricultural Waste: Certain types of agricultural waste, such as vegetable waste, green plant material, and fruit waste, have high moisture contents. When these materials undergo anaerobic digestion, the produced biogas tends to have a higher water vapor content.

- Animal Manure: Manure from livestock such as cows, pigs, and poultry contains a significant amount of water. Anaerobic digestion of these materials not only produces methane-rich biogas but also biogas with considerable water vapor due to the initial moisture present in the manure.

- Aquatic Biomass: Materials such as algae and aquatic plants have high water content. When these biomasses are used as feedstock for biogas production, the resulting gas can have a high level of water vapor.

In the event that the biogas source contains too much CH₄ for efficient operation, additional CCh can be introduced from a capture stage.

Various types of plasma reactors for performing plasma-based gas conversion exist in the art. The plasma reactor according to the present disclosure is designed for efficient and stable operation in a glow discharge regime, which is generally characterized by lower plasma temperatures when compared to the arc discharge regime. More specifically, the plasma reactor according to the present disclosure is designed to generate a stable glow discharge plasma for obtaining a high gas conversion performance, for instance for the conversion of greenhouse gases. As discussed above, a reaction of particular interest is the DRM process for converting at the same time carbon dioxide and methane. Although the plasma reactor according to the present disclosure is particularly suited for operating in a glow discharge regime, depending on particular operational settings, e.g. power supply used, and gas flow regimes, the plasma reactor might also operate in an spark, arc or transitional discharge regime.

The plasma reactors that are used in the present invention, are preferably atmospheric pressure plasma reactors as they typically operate at atmospheric pressure.

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

In another or a further embodiment, the plasma reactor operates at a temperature to between 2500K and 5000K, more preferably between 3000K and 4500K, and most preferably around 3500K. This high temperature is preferred for facilitating the reactions that lead to the formation of syngas.

In a preferred embodiment, the plasma reactor comprises plasma generating means, said means chosen from the list of:

- gliding arc (GA) glow discharge radiofrequency plasma (RF) microwave plasma (MW) inductively coupled plasma (ICP)

- capacitive coupled plasma (CCP) dielectric barrier discharge (DBD).

In a more preferred embodiment, the plasma reactor comprises plasma generating means, said means chosen from the list of:

- gliding arc (GA) glow discharge radiofrequency plasma (RF) microwave plasma (MW) dielectric barrier discharge (DBD).

Each of these reactor types possesses unique characteristics that can be harnessed to enhance the efficiency and effectiveness of the bi-reforming of methane (BRM) process. In an even more preferred embodiment, the plasma reactor comprises plasma generating means, said means being gliding arc (GA). The gliding arc reactor has the ability to maintain a stable discharge even at high flow rates. This characteristic is particularly advantageous in the context of BRM, where the flow rates of the gas mixtures can be adjusted to optimize the production of syngas. In another more preferred embodiment, the plasma reactor comprises plasma generating means, said means selected from gliding arc (GA) or glow discharge (GD). These plasma types are particularly well-suited for direct plasma-driven gas reforming processes, including dry reforming of methane (DRM), oxy-reforming of methane, and bi-reforming of methane (BRM). Their ability to operate efficiently at atmospheric pressure while maintaining stable plasma conditions enables high conversion of methane and carbon dioxide into syngas. Gliding arc and glow discharge plasmas promote effective electron-driven dissociation of CH4 and CO2, facilitating syngas production across different reforming pathways without requiring catalysts. These plasma systems provide a versatile approach to reforming reactions, allowing for optimized syngas composition by adjusting CO2, O2, or H2O content in the input stream while maintaining high process efficiency and scalability. Preferably, the plasma reactor is a contained plasma reactor. A contained plasma reactor ensures that the plasma discharge is confined within a controlled reaction environment, preventing unwanted interactions with external surfaces and maintaining consistent reaction conditions. More preferably, the plasma reactor is a contained, atmospheric gliding arc or contained, atmospheric glow discharge reactor. These reactor configurations have demonstrated significantly higher conversions under direct-plasma, non-catalytic conditions compared to other plasma reactor types. The atmospheric operation eliminates the need for vacuum systems, simplifying reactor design while reducing energy consumption and maintenance requirements.

Furthermore, gliding arc and glow discharge plasma reactors offer several advantages over radiofrequency (RF) and microwave (MW) plasma reactors. Specifically, GA and GD reactors exhibit much simpler operational setups, requiring fewer specialized components, such as complex impedance matching networks or waveguides, which are essential for RF and MW plasma systems. This simplicity translates to lower capital costs, easier scalability, and enhanced robustness for continuous operation. Moreover, GA and GD plasmas inherently generate moderate electron temperatures, which can drive the DRM reaction efficiently without excessive energy losses, improving process sustainability.

By utilizing a contained, atmospheric gliding arc or glow discharge plasma reactor, the present 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 the known challenges associated with plasma-catalytic systems and maximizing the advantages of non-catalytic syngas production. In a preferred embodiment, the plasma reactor is a contained atmospheric glow discharge or gliding arc reactor, wherein the cathode-anode distance, defined as the shortest distance between the cathode and the 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. Increasing the distance between the anode and the 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, leading to improved conversion efficiency and a higher syngas yield. A longer cathode-anode distance also extends the interaction time of the gas within the plasma zone, which positively influences the formation of CO and H2. However, an excessive distance can cause instability in the plasma discharge and increased electrode wear. By maintaining the cathode-anode distance within the optimized range of 50 mm to 80 mm, a balance is achieved between energy consumption, conversion efficiency, and plasma reactor stability, contributing to a robust and scalable reforming process.

In a preferred embodiment, the method involves operating the plasma reactor at a flow rate between 1 and 10⁶ L/min.

The plasma reactor, in this embodiment, is designed to handle a wide range of gas flow rates, thereby enabling the adaptability of the system. The 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 therefore, the efficiency of the reforming reactions. The ability to operate at low flow rates, such as 1 L/min, allows for the method to be used in small-scale operations where the production of the incoming gas streams, such as biogas, is limited. Conversely, the ability to operate at high flow rates, up to 10⁶ L/min, allows for the method to be used in large-scale operations where large volumes of incoming gas streams, such as biogas, are produced.

In a more preferred embodiment, the plasma reactor is operated at a flow rate between 10³ and 10⁵ L/min, which provides balance between the residence time of the gas in the reactor and the efficiency of the reforming reactions. The ability to operate the plasma reactor at different flow rates allows for the method to be adaptable to the varying composition of the incoming streams, for example biogas. The composition of the biogas can vary depending on the source of the biogas and the anaerobic digestion process. By adjusting the flow rate, the method can accommodate these variations and still produce syngas with the desired composition. This adaptability makes the method a versatile solution for the production of methanol from biogas.

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

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

At the broader end of the range, with H2/CO ratios between 2.5 and 3.0, the syngas contains an excess of hydrogen, which may lead to suboptimal carbon utilization and favor side reactions such as methane formation via the Sabatier reaction. While a higher hydrogen content can be advantageous for hydrogenation reactions, it generally necessitates additional CO supplementation or recycling to achieve the correct stoichiometry for methanol production.

Conversely, when the H2/CO ratio falls below 1.5, the syngas becomes hydrogendeficient, which can lead to incomplete methanol synthesis and an increased fraction of unreacted CO in the output stream.

The dry reforming process, as previously described, involves the reaction of methane and carbon dioxide in a plasma reactor. The resulting syngas, a mixture of carbon monoxide and hydrogen, is then preferably used in the production of methanol. The optimal ratio for methanol synthesis is generally considered to be around 2: 1, because of reaction (C).

Dry reforming of methane (DRM) can be enhanced through the use of catalysts that promote the conversion of methane and carbon dioxide into syngas (H2 and CO). Suitable catalysts for DRM typically include transition metal-based catalysts such as nickel (Ni), cobalt (Co), iron (Fe), and noble metals such as platinum (Pt), palladium (Pd), rhodium (Rh), and ruthenium (Ru), often supported on materials like alumina (AI2O3), ceria (CeO2), zirconia (ZrO2), or magnesium oxide (MgO). These catalysts aid in lowering the activation energy of the reaction, improving conversion efficiency, and enhancing selectivity toward syngas formation. While noble metals generally offer higher stability and resistance to carbon deposition, they are expensive, making nickel-based catalysts a more common choice due to their costeffectiveness despite their susceptibility to deactivation.

Preferably, no catalysts are present in the plasma reactor itself. In a particular preferred embodiment, the plasma reactor does not comprise a fixed-bed catalyst. In a further preferred embodiment, the plasma reactor does not comprise a catalyst. Plasma-based DRM operates through highly energetic conditions that facilitate the dissociation of methane and carbon dioxide without the need for catalysts.

A known limitation of catalytic DRM is catalyst deactivation, which can occur due to carbon deposition (coking), sintering of active metal sites, or poisoning by sulfur or other contaminants. Catalyst deactivation leads to continuous fluctuations in the resulting H2/CO ratio of the syngas, which has a profound impact on downstream processes, particularly in methanol synthesis, where precise control over the syngas composition is crucial. Additionally, while plasma-catalytic reactors hold significant potential in terms of reaction enhancement, they are extremely challenging to operate continuously in a stable, controlled, and scalable manner due to the complex interactions between plasma-generated species and the catalyst surface.

More preferably, if a catalyst is employed, it is used downstream of the plasma reactor to optimize syngas composition post-plasma conversion. Even more preferably, the plasma is contained separately from the catalyst to ensure a stable and controlled process, minimizing the risk of catalyst degradation caused by direct plasma exposure. The present application seeks to overcome the known issues of catalytic DRM by focusing on direct plasma DRM. This approach eliminates the constraints associated with catalyst deactivation in the primary conversion step, providing a more robust and stable method for syngas production. The challenges linked to plasma-catalytic reactors can be partially mitigated by employing a two- stage system where direct plasma DRM is followed by a catalytic reactor in series. In this configuration, the catalytic DRM reactor is primarily utilized to refine conversion efficiency and improve selectivity toward the desired syngas composition. Furthermore, more preferably, a liquid trap is included between the plasma reactor and the catalytic reactor. This feature aids in reducing catalyst deactivation by capturing condensed water, heavy hydrocarbons, or other contaminants that could poison the catalyst. Advantageously, the majority of DRM is conducted in a non-catalytic environment, which significantly prolongs catalyst lifetime and ensures a more stable and predictable syngas output.

In a preferred embodiment, the syngas produced in the plasma reforming step preferably comprises CH4, CO2, CO, and H2 in a combined amount of at least 90 vol%, more preferably at least 95 vol%, even more preferably at least 98 vol%, even more preferably at least 99.0 vol%, even more preferably at least 99.5 vol%, and most preferably up to 99.9 vol%. In another preferred embodiment, the syngas preferably comprises CH4, CO2, CO, H2, and H2O in a combined amount of at least 90 vol%, more preferably at least 95 vol%, even more preferably at least 98 vol%, even more preferably at least 99.0 vol%, even more preferably at least 99.5 vol%, and most preferably up to 99.9 vol%. More preferably, the syngas essentially consists of CH4, CO2, CO, H2, and H2O, and even more preferably, it essentially consists of CH4, CO2, CO, and H2, minimizing the presence of extraneous species. In a further preferred embodiment, the amount of byproducts, including heavier hydrocarbons and oxygenated compounds, is at most 2 wt.%, more preferably at most 1 wt.%, even more preferably at most 0.5 wt.%, even more preferably at most 0.2 wt.%, even more preferably at most 0.1 wt.%, and most preferably at most 0.05 wt.%.

Reforming reactors typically generate byproducts such as water, C2+ hydrocarbons, and oxygenated hydrocarbons. In the two-stage reactor setup of the present invention, these byproducts should be minimized as much as possible to prevent operational issues in downstream processing. In particular, the formation of hydrocarbons such as ethyne (C2H2) and ethene (C2H4) should be avoided, as these compounds contribute significantly to coking and reactor fouling, leading to instability in both the plasma reactor and the subsequent Fischer-Tropsch (FT) or methanol reactor.

Advantageously, the inventors have found that direct-plasma DRM in gliding arc and glow discharge reactors can maintain the total amount of hydrocarbons and liquid fractions below 1%, significantly reducing the risk of carbon deposition and improving reactor longevity. This low byproduct formation allows for seamless coupling with downstream FT reactors or methanol reactors, ensuring stable operation and high syngas conversion efficiency. By carefully controlling plasma conditions, the present invention enables a clean, high-purity syngas composition optimized for further processing, while minimizing process inefficiencies associated with undesired side reactions.

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

A "Fischer-Tropsch reactor" or "FT reactor" refers to a chemical reactor used for conducting the Fischer-Tropsch synthesis, a process that converts syngas— a mixture of carbon monoxide (CO) and hydrogen (H₂)— into liquid hydrocarbons, ranging from light fuels like gasoline to heavier waxy substances. This reactor is designed to facilitate the catalytic reaction under controlled conditions of temperature and pressure, optimizing the conversion of syngas to hydrocarbons.

The present invention is particularly directed toward a two-step process for methanol production, wherein the first step comprises plasma reforming of methane to produce syngas comprising CO and H2, and the second step involves feeding the syngas to a separate Fischer-Tropsch reactor, preferably a methanol reactor, to convert the syngas into methanol. This two-reactor setup provides significant advantages over single-reactor configurations, particularly in terms of process flexibility, efficiency, and product separation.

A key advantage of this two-step approach is the ability to independently optimize the operating conditions of each reactor. Plasma reforming of methane is most effectively conducted at or near atmospheric pressure, as higher pressures can destabilize 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 increase single-pass conversion rates. By maintaining separate reactors, each stage can be individually finetuned to achieve maximum efficiency without compromising the conditions required for the other step.

Another major benefit is the improved ability to separate and recycle unreacted gases. The methanol reactor produces both liquid-phase methanol and a gaseous fraction comprising unreacted CO, H2, and byproducts such as CO2. In the present invention, the output stream of the methanol reactor can be efficiently separated into liquid and gaseous phases, allowing the gaseous fraction to be recycled back to the methanol reactor to further increase conversion efficiency. This type of gas recycling is not feasible in a single-reactor setup, where plasma reforming and methanol synthesis would occur in the same environment, leading to inefficient reactant utilization and product dilution.

Furthermore, separating the plasma reforming step from the methanol synthesis step provides greater operational stability and scalability. The two-reactor system allows for better control of syngas composition, reducing fluctuations in the H2/CO ratio that could negatively impact methanol yield. Additionally, by decoupling these two stages, each reactor can be designed with materials and configurations that best suit its respective reaction conditions, leading to improved reactor longevity and reduced maintenance requirements. This modular approach ultimately enhances process efficiency, improves methanol yield, and provides a more robust and scalable pathway for sustainable methanol production.

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

In a particularly preferred embodiment, 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, and CH4, b. igniting a plasma in the plasma reactor, thereby allowing the CO₂, H₂O and CH4 to react and form syngas comprising CO and H₂, and c. supplying said syngas to a methanol reactor, wherein said CO and H₂ in the syngas are at least partially converted to methanol in said methanol reactor.

The FT reactor is designed to operate at conditions that favor the conversion of syngas to the desired fuel products, such as methanol. The temperature in the FT reactor is preferably between 150°C and 350°C, more preferably between 200°C and 300°C, and most preferably between 220 and 300°C. The pressure in the methanol reactor can be between 20 and 200 bar, more preferably between 50 and 100 bar. The output stream of the FT reactor comprises the liquid fuel products and optionally unreacted gas products. In case of the methanol reactor, the output of the methanol reactor comprises at least methanol, and optionally unreacted gas products such as CO, CO? and H₂.

In a preferred embodiment, an output stream comprising said methanol is extracted from said methanol reactor, wherein said output stream is supplied to a separation drum, wherein unreacted gaseous products such as CO₂, CO and H₂ are separated from said liquid phase.

The separation drum exploits the differences in physical properties (like boiling point, density) between these components to separate the gaseous phase from the liquid phase. The effluent output stream of the reactor is fed, preferably by fluid connection, into a separation drum, a vessel designed to allow the mixed stream to settle and separate into two distinct phases:

• top Layer (Gas Phase): this layer contains the unreacted gases and possibly some vapors of the product (methanol) and byproducts (like water).

• bottom Layer (Liquid Phase): this layer primarily consists of liquid methanol, and optionally water and any heavier compounds present in the mixture.

In a further preferred embodiment, the gas phase, rich in unreacted hydrogen, carbon monoxide, and carbon dioxide, is recycled back to the methanol reactor for further conversion. This recycling process helps in improving the overall conversion efficiency by giving the unreacted gases another chance to react.

In a further preferred embodiment, said liquid phase is supplied to a separation column, wherein said methanol is separated from said liquid phase. The methanol is separated from other liquid products in said liquid phase.

The liquid phase, comprising at least methanol is preferably sent to a distillation column or another separation unit. Here, methanol is separated from water and any other impurities to produce a high-purity methanol product.

In a further or another preferred embodiment, said liquid phase further comprises water, wherein said liquid phase is supplied to a separation unit, and wherein at least said water and said methanol are separated. The invention could, in another aspect, be described as a method for optimizing syngas. Herein the embodiments of step a) and b) as described above correspond to the embodiments of this method.

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, and b. igniting a plasma in the plasma reactor, thereby allowing the CO2, H₂O and CH₄ to react and form syngas comprising CO and H₂.

In a particularly preferred embodiment, said one or more gaseous input streams comprise a total amount of CH₄ and a total amount of CO2 in a volume ratio of at least 2.

The syngas has preferably a H₂ to CO volume ratio of between 1.5 and 2.5.

In a second aspect, the invention relates to a system for hydrocarbon production, preferably methanol production.

The system preferably comprises: a plasma reactor comprising a plasma reactor chamber with a plasma zone, the plasma reactor being configured to ignite a plasma in the plasma zone, the plasma reactor further comprising a plasma inlet for a gaseous input stream and a plasma outlet for a gaseous output stream; and a methanol reactor comprising a reactor chamber, the methanol reactor further comprising a methanol reactor inlet for a gaseous input stream and a methanol reactor outlet for an at least partially liquid output stream.

In a particularly preferred embodiment, said plasma outlet is fluidly connected to said methanol reactor inlet.

In another preferred embodiment, the system optionally comprises a liquid-trap or separation drum fluidly connected between the plasma reactor and the methanol reactor. More preferably, the syngas passes through from the plasma reactor to the methanol reactor; but the minor liquid fraction is separated. The inclusion of such a separation stage serves to remove liquid-phase components and solid impurities prior to introducing the syngas into the methanol reactor. Preferably, the liquid-trap or separation drum is configured to separate condensed water, unreacted hydrocarbons, and any entrained particulates that may form during plasma reforming. More preferably, the separation drum is designed to operate passively, relying on differences in phase behavior rather than requiring additional energy- intensive separation processes.

Advantageously, this intermediate separation step reduces the accumulation of liquid and solid impurities within the methanol production loop, thereby limiting the buildup of undesirable byproducts that could otherwise require complex downstream purification. By removing contaminants before the syngas enters the methanol reactor, this embodiment significantly reduces reactor fouling, extends catalyst lifetime, and minimizes deactivation risks associated with the deposition of coke or heavy hydrocarbons. Additionally, the removal of excess water prior to methanol synthesis ensures that the H2/CO ratio remains within the preferred range, optimizing methanol yield and selectivity. These benefits are achieved without necessitating a full-scale gas cleanup stage, thereby avoiding the high energy costs typically associated with conventional gas-liquid separation units. As a result, the incorporation of a liquid-trap or separation drum provides an efficient, low-energy solution to maintaining reactor performance, ensuring process stability, and improving overall methanol production efficiency. In a preferred embodiment, the methanol reactor is a fixed-bed catalytic reactor configured for the hydrogenation of carbon monoxide and carbon dioxide into methanol. The reactor preferably comprises a reaction chamber containing a heterogeneous catalyst, wherein said catalyst is preferably selected from copperbased catalysts, more preferably Cu/ZnO/AhOs, even more preferably a modified Cu/ZnO-based catalyst with enhanced thermal stability and resistance to deactivation. The methanol reactor is preferably designed to operate under elevated pressures to optimize conversion efficiency and maintain catalyst performance over extended operational periods.

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 between 90 and 100 bar. Operating at high pressures enhances the conversion of syngas to methanol by shifting the reaction equilibrium toward methanol synthesis, thereby improving single-pass efficiency. In a further 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 between 220°C and 280°C. These temperatures ensure optimal catalytic activity while minimizing undesirable side reactions, such as excessive water formation or catalyst sintering.

In a preferred embodiment, said system comprises further a separation drum fluidly connected to said reactor outlet, wherein said drum separation stage comprises a drum outlet for a gaseous output stream, and a drum outlet for a liquid output stream.

The inclusion of a separation drum, fluidly connected to the reactor outlet, introduces an intermediate step in the system, enhancing the separation of gaseous and liquid phases produced during the methanol synthesis process. This separation drum, equipped with outlets for both gaseous and liquid output streams, allows for the efficient partitioning of unreacted gases from the produced methanol and water mixture. This separation is crucial for recycling gases back to the methanol reactor, thereby improving the overall efficiency and yield of the methanol production process by ensuring that as much of the reactant gases as possible are converted into methanol. In a preferred embodiment, said drum outlet for a gaseous output stream is fluidly connected to a methanol reactor inlet of said methanol reactor. The gaseous output stream from the drum is fluidly connected back to the methanol reactor inlet. This configuration is advantageous because it enables the recycling of unreacted gases directly into the reactor for further conversion. This recycling loop significantly enhances the process's efficiency, minimizing waste and reducing the need for fresh feedstock, leading to a more sustainable and cost-effective operation.

In a preferred embodiment, said drum outlet for a liquid output stream is fluidly connected to an inlet of a separation column suitable for separating liquid synthesis products. This extends the system's functionality by connecting the drum outlet for the liquid output stream to an inlet of a separation column, which is specifically designed to separate methanol from the liquid phase. This arrangement ensures that the methanol-water mixture is efficiently purified, with methanol being isolated to meet product quality standards. The direct connection between the drum and the separation column streamlines the process flow, reducing potential losses or contamination of the product stream, and ensures that the highest possible purity of methanol is achieved. This step is critical for producing commercial-grade methanol, suitable for various applications, including fuel, solvents, and industrial chemicals, enhancing the system's versatility and marketability of the produced methanol.

The present invention will be now described in more details, referring to examples that are not limitative.

EXAMPLES AND DESCRIPTION OF FIGURES

With as a goal illustrating better the properties of the invention the following presents, as an example and limiting in no way other potential applications, a description of a number of preferred applications of the method for examining the state of the grout used in a mechanical connection based on the invention, wherein:

Figure 1 schematically describes an embodiment of the invention.

Methane and carbon dioxide are supplied to a plasma reactor 101, wherein the dry reforming of methane is carried out following reaction (B), and a syngas 102 comprising CO and H₂ is obtained.

CH₄ + CO₂ -► 2CO + 2H₂ (B) CO2 and the hydrogen carrier can be captured from industrial and agriculture processes. The capture technology is considered as background, and can include the following methods:

• Adsorption (chemical, physical)

• Adsorption (pressure swing adsorption (PSA), metal organic frameworks (MOF))

• Cryogenic distillation

• Membranes

• Chemical looping

When the resulting syngas is preferentially used for the production of methanol according to reaction (D), a molar ratio of CO and H2 of 1 :2 in the syngas is optimal. co + 2H₂ -► CH₃OH (C)

The production of methanol according to an embodiment of the current invention is shown in figure 2. In the plasma unit 201, a mixture of hydrogen source 204 and CO₂ 203 is fed. In this embodiment of the invention, the syngas stream 202 can be converted directly to fuels or olefins 207 via a Fischer-Tropsch reactor 206. Production of methanol (MeOH) is particularly attractive for the chemical and maritime shipping industry.

In the methanol reactor, the following reactions take place under controlled pressure and temperature:

C0₂ + 3H₂ -> CH3OH + H₂0 AH = -50 kJ/mol

CO + 2H₂ -> CH₃OH AH = -91 kJ/mol

CO₂ + H₂ -> CO + H₂O AH = 41 kJ/mol

As it can be seen, water is an unwanted product in the final stream. Furthermore, the feed gas does not convert completely to liquids, for which a separation drum is used - all unreacted gas is fed back to the reactor. Then, the mixture of MeOH and water is fed into a separation (distillation) column, which separates the final product into 2 streams - clean MeOH and excess water. This is shown in figure 3.

In the plasma unit 301, a mixture of hydrogen source 304 and CO₂ 303 is fed. In this embodiment of the invention, the syngas stream 302 can be converted directly to fuels or olefins 307 via a Fischer-Tropsch reactor 306. The products from the FT reactor 306 are supplied to a separation drum 308 to separate the unreacted gas 309, which is supplied back to the FT reactor 306. The unreacted gas can for example comprise CO2, CO and/or H₂. The mixture of methanol and water 313 is fed into a separation column 310, which separates the final product into a water stream 311 and a methanol stream 312.

It is clear that the method according to the invention, and its applications, are not limited to the presented examples.

Claims

1. 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 CO? and CH₄, b. igniting a plasma in the plasma reactor, thereby dry reforming said CH₄ to form a syngas comprising CO and H₂, c. supplying said syngas to a methanol reactor, wherein said CO and H₂ in the syngas are at least partially converted to a liquid phase comprising at least methanol, characterized in that, said plasma reactor and said methanol reactor are fluidly connected, and in that said gaseous input streams comprise a total amount of CH₄ and a total amount of CO₂ in a volume ratio of at least 2.

2. Method according to claim 1, wherein the methanol reactor is operated at a pressure of between 50 and 100 bar.

3. Method according to any of the previous claims, wherein the methanol reactor is operated at a temperature of between 220 and 300 °C.

4. Method according to any of the previous claims, wherein an output stream comprising said methanol is extracted from said methanol reactor and wherein said output stream is supplied to a separation drum, wherein unreacted gaseous products such as CO₂, CO and H₂ are separated from said liquid phase.

5. Method according to claim 4, wherein said un-reacted gaseous products are recycled to the plasma reactor.

6. Method according to claim 4 or 5, wherein said liquid phase is supplied to a separation column, wherein said methanol is separated from said liquid phase.

7. Method according to any of the previous claims, wherein said liquid phase further comprises water.

8. Method for methanol production according to any of the previous claims, wherein said syngas has a H₂ to CO volume ratio of between 1.5 and 2.5.

9. Method according to any of the previous claims, wherein said liquid phase further comprises water, and wherein said liquid phase is supplied to a separation unit, wherein at least said water and said methanol are separated.

10. Method according to any of the previous claims, wherein said CO₂ is captured in the form of adsorption, cryogenic distillation membranes or chemical looping.

11. Method according to any of the previous claims, wherein said gaseous input stream comprises CH₄ sourced from the list of: fossil fuel, biogas, synthesis gas, or gas mixtures from CO? hydrogenation.

12. A system for methanol production, comprising: a plasma reactor comprising a plasma reactor chamber with a plasma zone, the plasma reactor being configured to ignite a plasma in the plasma zone, the plasma reactor further comprising a plasma inlet for a gaseous input stream and a plasma outlet for a gaseous output stream; a methanol reactor comprising a reactor chamber, the methanol reactor further comprising a methanol reactor inlet for a gaseous input stream and a methanol reactor outlet for a liquid output stream, characterized in that said plasma outlet is fluidly connected to said methanol reactor inlet.

13. System according to claim 12, wherein said system comprises further a separation drum fluidly connected to said methanol reactor outlet, wherein said separation drum comprises a drum outlet for a gaseous output stream, and a drum outlet for a liquid output stream.

14. System according to claim 13, wherein said drum outlet for a gaseous output stream is fluidly connected to a methanol reactor inlet of said methanol reactor.

15. System according to claim 13 or 14, wherein said drum outlet for a liquid output stream is fluidly connected to an inlet of a separation column suitable for separating methanol from a liquid phase.

16. Use of a system according to any of claims 12 to 15 for production of methanol.