WO2021239811A1

WO2021239811A1 - Gas to methanol with coproduction of hydrogen

Info

Publication number: WO2021239811A1
Application number: PCT/EP2021/064050
Authority: WO
Inventors: Romuald COUPAN; Christophe Thille; Jean-Pierre Dath; Walter Vermeiren
Original assignee: Total Se
Priority date: 2020-05-29
Filing date: 2021-05-26
Publication date: 2021-12-02

Abstract

The disclosure relates in its first aspect to a process for converting a stream comprising methane into methanol. Said process comprises the steps of (a) providing a first stream (1, 7) comprising methane; (b) providing a second stream (13) comprising oxygen; (c) contacting said first stream (1, 7) with said second stream (13) under oxidation reaction conditions to obtain a third stream (15) comprising at least methanol and water; (d) separating water from said third stream (15) to recover a water stream (21; 33) and a fourth stream (49) comprising methanol; (e) subjecting at least a part of said water stream (21; 33) from step (d) to an electrolysis step to produce said second stream (13) and a hydrogen stream (43); and optionally, (f) recovering methanol from said fourth stream (49). The second aspect of the disclosure relates to an installation for carrying out the process of the first aspect.

Description

GAS TO METHANOL WITH COPRODUCTION OF HYDROGEN

Field of the disclosure

The present disclosure relates to the production of methanol from natural gas.

Technical background

Methanol is widely used in different applications such as the production of dimethyl ether, which may be used in aerosols or as an alternative fuel for diesel engines; the transesterification of triglycerides to produce biodiesel; or as a solvent or a fuel for engines. Also, methanol can be used as feedstock in processes such as Methanol-to-Gasoline (MTG), Methanol-to-Olefins (MTO), and Methanol-to-Propylene (MTP). The conversion of methanol (MTG, MTO, MTP) can be summarized by the chemical equation (I): n CHsOH ®· CnH_2n + n H₂0 (I)

With regards to the interesting potential of methanol and the need for producing it, natural gas is an available fossil resource that can be valorised as feedstock for the petrochemical industry and that is cheap. Accordingly, the conversion of light alkanes present in the natural gas into products like syngas, methanol, olefins or aromatics is highly valuable. Oxygen-based processes are the current practice for natural gas conversion. However, processes involving the presence of oxygen leads unavoidably to the formation of carbon dioxide and water in the final product streams as shown in the chemical equation (II):

CH₄ + 2 0₂ C0₂ + 2 H₂0 (II)

The carbon efficiency of any processes contacting alkanes and oxygen does not exceed 75%.

Among the commercial processes, one can highlight the following reforming processes: Steam Methane Reforming (SMR), Auto-Thermal Reforming (ATR), Dry Methane Reforming (DMR), Partial Oxidation Reforming (POX), as exemplified by the chemical equations (lll)-(V):

Synthesis gas (i.e. a mixture of carbon monoxide and hydrogen) can be further converted to methanol in the Gas-to-Methanol process (GTM), as indicated in the chemical equation (VI): GTM : CO + 2 H₂ ®· CH₃OH (VI)

However, the issue with the formation of carbon dioxide and water is then their further transformation into valuable chemicals (such as the conversion of water into hydrogen and the reaction of the hydrogen with the carbon dioxide to form various useful chemical) is highly demanding in energy. There is thus a need for reactivation of these compounds at low energy costs.

For example, W02008/143940 describes an improved continuous process for converting methane, natural gas, and other hydrocarbon feedstocks into one or more of methanol, higher hydrocarbons, amines, or other products which comprises continuously cycling through hydrocarbon halogenation, product formation, product separation, notably from coke, and electrolytic regeneration of halogen combined with hydrogen production. The formation of the coke has an impact on the stability of the catalyst, which must be regenerated when a drop in the conversion is observed.

The document US2012/0226080 discloses a process to generate methanol. The process starts by providing water (such as seawater) and performing electrolysis of said water. The hydrogen that is produced is reacted with a stream of carbon dioxide to form a first methanol portion. The oxygen that is produced can be reacted with a stream of hydrocarbons to form a second methanol portion. A seawater desalination system might be provided to improve the working of the electrolysis reaction.

As the chemical market is still growing, there is a need for competitive gas to methanol processes with improved energy and/or carbon efficiency.

Summary of the disclosure

According to a first aspect, the disclosure provides for a process for converting a stream comprising methane into methanol, said process being remarkable in that it comprises the following steps: a) providing a first stream comprising methane (CFU); b) providing a second stream which is an oxygen-rich (0₂-rich) stream; c) contacting said first stream with said second stream under oxidation reaction conditions to obtain a third stream comprising at least methanol (CH₃OH) and water (H₂O); d) separating water from said third stream to recover a water stream and a fourth stream comprising methanol; e) subjecting at least a part of said water stream recovered from step (d) to an electrolysis step to produce an oxygen stream and a hydrogen (H₂) stream, wherein the oxygen stream is recycled into the second stream; f) optionally, recovering a methanol stream from said fourth stream. Surprisingly, this process wherein a direct methane to methanol (DMTM) process is combined with water electrolysis allows gaining in energy efficiency since not only methanol is produced from methane, but also hydrogen. Hydrogen is a valuable product having several uses such as carbon-free energy or as feedstock.

The implementation of an electrolysis step has allowed converting one of the side products indicated in equation (II), namely water, obtained from the oxidation of methane, into one valuable compound which is hydrogen. The water collected as a side product is pure and does not need further treatment (such as cation removing treatment) to be used with an electrolysis membrane. This renders the whole process cheaper and cost-efficient.

Also, the loop of recycling of the oxygen-rich stream allows limiting the needs of reactants. Since no catalyst is needed and since the oxygen-rich stream is recycled back to step c), the process can be performed anywhere and, for example, on the place wherein natural gas comprising methane is extracted. Natural gas is then easily transformed into a liquid (i.e. methanol) that is easier to transport for further transformation.

As will be described in detail, the other side product indicated in equation (II), namely CO2, can also be collected and converted into methanol, rendering the process carbon-efficient in that no or little CO2 is released into the atmosphere.

The disclosure provides a process wherein one or more of the side products of equation (II) are collected and further converted. This further conversion is easy and cost-effective the stream of water and CO2 generated from the reaction (II) are pure streams, devoid of contaminants such as sulphur or cations. The management of the side-products optimizes the whole process and increases its efficiency.

In an embodiment, step (a) of providing a first stream comprising methane comprises providing a natural gas comprising methane at a content of at least 75 mol.% based on the total molar content of said natural gas, preferably at least 80 mol.%, more preferably at least 90 mol.%, and even more preferably of at least 95 mol.% of methane based on the total molar content of said natural gas. For example, the first stream is a methane stream.

For example, step (a) of providing a first stream comprising methane comprises a sub-step of purifying the natural gas to remove sulphur and/or nitrogen. Optionally, step (a) of providing a first stream comprising methane comprises a sub-step of purifying the natural gas to remove oxygen, carbon dioxide and/or carbon monoxide. The removal of oxygen, carbon dioxide and/or carbon monoxide is performed when the content of these components is or become too high, for example, due to the presence of a recycling loop. Advantageously, step (b) of providing a second stream which is an oxygen-rich stream is performed at the start of the process to initiate the conversion of methane into methanol and is stopped or at least reduced as soon as step (e) recycles at least 50 vol.% of the oxygen- rich stream, preferably at least 70 vol.%, more preferably at least 80 vol.%, even more preferably at least 90 vol.%, most preferably at least 95 vol.%. Even most preferably, step (b) of providing a second stream which is an oxygen-rich stream is performed at the start of the process to initiate the conversion of methane into methanol and is stopped as soon as step (e) recycles the whole of the oxygen-rich stream. Indeed, the recycle stream which is an oxygen stream will replace all or part of the original oxygen-rich stream provided to initiate the reaction. The original oxygen-rich stream is air or is produced by an air-conversion unit. Alternatively, a stream of water is directed into a water electrolysis unit of the installation to produce an oxygen stream and a hydrogen stream wherein the oxygen stream initiates the conversion of methane into methanol.

With preference, step (c) is carried out in the absence of a catalyst. The fact that no catalyst is needed for the oxidation of methane into methanol in the presence of an oxygen-rich stream allows having a cost-effective and simple process. Besides, there is no need for maintenance of the catalyst, such as activation steps and/or replacement of the catalyst in the reactors due to deactivation. This also suppresses the need for recycling the catalyst.

One or more of the following features can advantageously further define the step (c) of the present process which is carried out in the absence of a catalyst:

- The oxidation reaction conditions of step (c) comprise a temperature ranging between 300°C and 600°C, preferably between 320°C and 550°C, more preferably between 350°C and 500°C, even more preferably between 370°C and 480°C, most preferably between 390°C and 470°C.

- The oxidation reaction conditions of step (c) comprise a pressure ranging from 4.0 MPa to 20.0 MPa, preferably from 4.5 MPa to 12.0 MPa, more preferably from 5.0 MPa to 12.0 MPa, even more preferably from 5.5 MPa to 8.0 MPa.

- The oxidation reaction conditions of step (c) comprise oxygen to methane ratio ranging between 0.020:1 and 0.20:1, preferably between 0.020:1 and 0.15:1; more preferably between 0.025:1 and 0.10:1 , and even more preferably between 0.030:1 and 0.06:1.

One or more of the following features can advantageously further define step (e) of subjecting said water stream from step (d) to an electrolysis step:

Step (e) is carried out at a temperature ranging between 50°C and 1000°C, preferably from 100°C to 800°C, more preferably from 200°C to 600°C. Step (e) is carried out at a temperature of at least 50°C, preferably at least 100°C, more preferably at least 150°C, even more preferably at least 200°C; and/or of at most 1000°C, preferably of at most 900°C, more preferably of at most 800°C, even more preferably of at most 700°C.

Step (e) is carried out at a pressure ranging between 0.1 MPa and 20.0 MPa, preferably from 1.0 MPa to 15.0 MPa, more preferably from 5.0 MPa to 10.0 MPa.

In a preferred embodiment, the fourth stream further comprises carbon dioxide and the process further comprises a step of recovering said carbon dioxide conducted after step (d) to recover a carbon oxides stream comprising at least carbon dioxide and a remaining stream comprising at least methanol.

This embodiment of the process that includes the valorisation of the carbon oxides allows improving the carbon efficiency of the process since the CO2, which is the second main side- products exemplified in equation (II), can be recovered and reused for other purposes, such as for further production of methanol.

Accordingly, with preference, the process further comprises a step of contacting said carbon oxides stream with a hydrogen stream in presence of one or more catalysts under reaction conditions to produce methanol and water. With preference, said hydrogen stream is the hydrogen stream produced in step (e) and/or the methanol and water produced in said additional step are recycled with the third stream obtained in step (c).

In a preferred embodiment, the process further comprises a step of contacting said carbon oxides stream with a hydrogen stream in presence of one or more catalysts under reaction conditions to produce methanol and water wherein said hydrogen stream is the hydrogen stream produced in step (e) and wherein the methanol and water produced in said additional step are mixed with the third stream obtained in step (c).

Wth this configuration, the carbon oxides stream comprising at least carbon dioxide, which has been recovered is reused in the process itself to enhance the production of methanol. It is also noted that the other side products illustrated in equation (II), namely water, is used to be converted into hydrogen by electrolysis, which, at its turn, is reused in the process itself to convert the carbon dioxide into methanol and subsequently increases the yield of the methanol.

In an embodiment, the process further comprises the step of separating the remaining stream into a gaseous stream comprising carbon monoxide, hydrogen and unreacted methane. Wth preference, the process further comprises a step of recovering from the gaseous stream unreacted methane to form a methane stream which is optionally recycled into step (c) and/or a step of recovering from the gaseous stream carbon monoxide and/or hydrogen, to form a stream comprising carbon monoxide and/or hydrogen, said stream comprising carbon monoxide and/or hydrogen is optionally mixed with said carbon oxides stream.

With this configuration, the carbon monoxide, which is also formed during the oxidation of methane by oxygen, is, at its turn, recovered and can be reused along the carbon dioxide to improve the yield in methanol.

Whichever embodiment is chosen, said one or more catalysts of the step of contacting said carbon oxides stream with a hydrogen stream are preferably one or more catalysts selected from the list comprising indium oxide catalyst, Cu-Zn/AhCh, Cu-Zn0-Ga₂0₃/SiC>₂, Cu-ZnO- Al203/ZrC>2, ZnO, Au/ZnO, Au/Fe2C>3, Au/TiC>2, Au/ZrC>2, Au/l_a2C>3, Au/ZnFe2C>4, Fe2C>3, Au/Fe2C>3, Cu/ZnO, CeC>2, T1O2, ZrC>2, La2C>3, ZnFe2C>3, and a combination thereof, preferably indium oxide catalyst and/or Cu-ZnO-AhCh/ZrC^.

Whichever the preferred embodiment is chosen, with preference, the reaction conditions of the step of contacting said carbon oxides stream with a hydrogen stream comprises one or more of: a molar ratio CO/CO2 ranging between 0:1 and 2:1; preferably between 0.25:1 and 1.75:1; more preferably between 0.5:1 and 1.5:1. a molar ratio H2/(CO+CC>2) ranging between 3 and 15; preferably between 4 and 14, more preferably between 5 and 13, more preferably between 7 and 11. a temperature ranging between 200°C and 250°C; preferably between 210°C and 240°C, more preferably between 220°C and 230°C. a pressure ranging between 6.0 MPa and 8.0 MPa, preferably between 6.5 MPa and 7.5 MPa.

In an embodiment, the fourth stream and the optional remaining stream comprising methanol further comprise unreacted methane, and the process further comprises a liquid-gas separation step conducted on the fourth stream or the remaining stream when present, to recover a liquid stream comprising at least methanol and a gaseous stream comprising at least unreacted methane, and a step of recycling the unreacted methane into the first stream. Wth preference, the gaseous stream comprising at least unreacted methane further comprises one or more selected from carbon dioxide, carbon monoxide and hydrogen, and the step of recycling the unreacted methane into the first stream comprises a sub-step of separating unreacted methane from the one or more selected from carbon dioxide, carbon monoxide and hydrogen to provide an unreacted methane stream and recycling the unreacted methane stream into the first stream.

In an embodiment, the process further comprises the step of separating the remaining stream into a liquid stream comprising methanol and formaldehyde. With preference, the process further comprises a step of recovering by distillation of the liquid stream a methanol stream and/or a formaldehyde stream, the water stream recovered from step (d) being optionally mixed with said liquid stream before said step of recovering by distillation of the liquid stream and/or before step (e).

According to a second aspect, the present disclosure provides for an installation for carrying out the process for converting a stream comprising methane into methanol according to the first aspect, said installation being remarkable in that it comprises

- a methane conversion unit;

- a product separation unit; and

- a water electrolysis unit; wherein the methane conversion unit, the product separation unit and the water electrolysis unit are fluidically connected in series, the product separation unit being downstream of said methane conversion unit and upstream of said water electrolysis unit; and wherein said product separation unit comprises a first distillation column in connexion with a line to conduct a water stream exiting from said first distillation column to said water electrolysis unit, and another line to recover a fourth stream comprising at least methanol exiting from said first distillation column.

Wth preference, the product separation unit comprises at least one additional distillation column arranged downstream the first distillation column to perform one or more product separations on the fourth stream.

Wth preference, said installation further comprises a pressurization unit disposed upstream of said methane conversion unit.

In an embodiment, said installation further comprises within the product separation unit a CO₂- separator. Wth preference, said installation further comprises a carbon oxides valorisation unit disposed downstream of said CC>₂-separator, the installation comprising a line directing a CO₂ stream exiting said CC>₂-separator to said carbon oxides valorisation unit.

In an embodiment, the installation further comprises a methane separator within the product separation unit. With preference, the installation comprises a line recycling a methane stream exiting said methane separator to said methane conversion unit and/or the installation further comprises a carbon oxides valorisation unit disposed downstream of said methane separator, the installation comprising a line directing a stream comprising carbon monoxide and/or hydrogen exiting said methane separator to said carbon oxides valorisation unit.

For example, the installation further comprises a carbon oxides valorisation unit disposed downstream of the product separation unit, and one or more of the following features can be used to further define the installation:

- the water electrolysis unit comprises a line to conduct a hydrogen stream exiting said water electrolysis unit to said carbon oxides valorisation unit.

- the carbon oxides valorisation unit comprises a syngas-to-methanol reactor; with preference, said syngas-to-methanol reactor comprises a line to conduct a stream comprising at least methanol and/or water into the product separation unit.

Description of the figures

Figure 1 illustrates the installation of the present disclosure according to a first embodiment;

Figure 2 illustrates the installation of the present disclosure according to a second embodiment wherein the installation comprises a carbon oxides valorisation unit.

Detailed description

For the disclosure, the following definitions are given:

The feed stream of the process, i.e., the first stream comprising methane, is a gaseous stream, preferably natural gas and/or other methane-rich hydrocarbon sources. The first stream can be treated in an outside battery limit (OSBL) plant where the majority of one or more selected from sulphur-containing compounds and/or nitrogen are removed. The efficiency of the conversion of the feed stream can further be enhanced by an optional step of removing at least a part of the oxygen, carbon dioxide and/or carbon monoxide present in the feed stream; or at least a part of the carbon dioxide and/or carbon monoxide present in the feed stream.

Zeolite codes (e.g., MFL.) are defined according to the “Atlas of Zeolite Framework Types", 6^th revised edition, 2007, Elsevier, to which the present application also refers.

The Si/AI atomic ratio corresponds to the content of S1O₂ divided by the content of AI₂O₃ taking into account the fact there are two atoms of aluminium for one atom of silicon. The silicon to aluminium molar ratio (also stated as SAR) corresponds to the molar content of S1O₂ divided by the molar content of AI₂O₃ notwithstanding the proportion of the Si atoms over the Al atoms in the chemical formula of the zeolite. Therefore, the value of the SAR or Si/AI molar ratio always corresponds to twice the value of the Si/AI atomic ratio.

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms "comprising", "comprises" and "comprised of" also include the term “consisting of”.

The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g., 1 to 5 can include 1 , 2, 3, 4, 5 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the recited endpoint values themselves (e.g., from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

The particular features, structures, characteristics or embodiments 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.

The process and the installation for carrying out the process will be jointly described by reference to figures 1 and 2.

The disclosure provides a process and an installation for the conversion of natural gas into methanol.

The process of the present disclosure is a process for converting a stream comprising methane into methanol, said process being remarkable in that it comprises the following steps: a) providing a first stream (1, 7) comprising methane; b) providing a second stream 13 which is an oxygen-rich stream; c) contacting said first stream (1 , 7) with said second stream 13 under oxidation reaction conditions to obtain a third stream 15 comprising at least methanol and water; d) separating water from said third stream 15 to recover a water stream (21; 33) and a fourth stream 49 comprising methanol; e) subjecting at least a part of said water stream (21 ; 33) recovered from step (d) to an electrolysis step to produce an oxygen stream 95 and a hydrogen stream (43, 47) wherein the oxygen stream 95 is recycled into the second stream 13; f) optionally, recovering a methanol stream 31 from said fourth stream 49.

The feed stream of the process The first stream (1, 7) is the feed stream of the process. According to the disclosure, the first stream (1 , 7) is or comprises natural gas. For example, the first stream (1 , 7) is a natural gas comprising methane. For example, the first stream (1, 7) is a natural gas comprising methane at a content of at least 75 mol.% of the total molar content of said natural gas; preferably at least 85 mol.%, more preferably at least 90 mol.%, and even more preferably of at least 95 mol.% of methane.

The first stream (1 , 7) can also comprise C2+ hydrocarbons. The C2+ hydrocarbons present in the first stream (1 , 7) may include, for example, C2-C5 alkanes. As used herein, the term “C2-C5 alkanes” refers to ethane, propane, butane, pentane, or mixtures thereof.

The first stream 1 can be conveyed into a pressurization unit 93, which comprises a compressor 3 which generates a pressurized first stream 7. For example, the pressure reached by the first stream 1 is ranging from 4.0 MPa to 20.0 MPa, preferably from 4.5 MPa to 12.0 MPa, more preferably from 5.0 MPa to 12.0 MPa, even more preferably from 5.5 MPa to 8.0 MPa. It is interesting to note that a pressurized stream of natural gas can straightforwardly be used in the process of the present disclosure, avoiding the need to transport such a gaseous stream and to pressurize it. In compressor 3, an amount of gas can be purged to recover a fuel gas stream 5.

Advantageously, the first stream 1 and/or the pressurized first stream 7 is directed to a heat exchanger 9, for example, disposed within the pressurization unit 93 as shown in figures 1 and 2, so that the first stream (1 , 7) comprising methane reaches the required temperature for conversion before entering into the methane conversion unit 85. For example, the temperature of the first stream (1 , 7) comprising methane is ranging between 300°C and 600°C, preferably between 320°C and 550°C, more preferably between 350°C and 500°C, even more preferably between 370°C and 480°C, most preferably between 390°C and 470°C.

Conversion of the methane in the methane conversion unit 85

Within the methane conversion unit 85, the first stream (1 , 7) comprising methane enters into the direct methane to methanol reactor 11, i.e., DMTM reactor 11, where the first stream (1, 7) comprising methane is put into contact with a second stream 13 which is an oxygen-rich stream. For example, the second stream 13 comprises at least 75 mol.% of oxygen based on the total molar content of the second stream 13, preferably at least 85 mol.%, more preferably at least 95 mol.%, even more preferably at least 99 mol.%. Most preferably, the second stream 13 comprises only oxygen. In the DMTM reactor 11, the pressure range is advantageously kept at the same level as it was set by compressor 3, namely ranging from 4.0 MPa to 20.0 MPa, preferably from 4.5 MPa to 12.0 MPa, more preferably from 5.0 MPa to 12.0 MPa, even more preferably from 5.5 MPa to 8.0 MPa. Similarly, the temperature is also advantageously kept at the same level it was set by the heat exchanger 9, namely ranging between 300°C and 600°C, preferably between 320°C and 550°C, more preferably between 350°C and 500°C, even more preferably between 370°C and 480°C, most preferably between 390°C and 470°C. Alternatively, when no compressor nor heat exchanger are placed upstream to the DMTM reactor 11 , the pressure and/or the temperature can be brought by the DMTM reactor 11 itself to this pressure range and/or to this temperature range.

The oxidation of methane into methanol in the DMTM reactor 11 is preferably performed in the absence of a catalyst.

Advantageously, the oxidation of methane into methanol in the DMTM reactor 11 is performed with oxygen to methane ratio ranging between 0.020:1 and 0.20:1, preferably between 0.020:1 and 0.15:1; more preferably between 0.025:1 and 0.10:1 ; and even more preferably between 0.030:1 and 0.06:1.

The conversion of methane into methanol provides a third stream 15, comprising at least methanol and water. For example, the third stream 15 can also comprise formaldehyde, carbon dioxide, carbon monoxide, hydrogen and unreacted methane. The conversion of methane is limited to about 3%-10% to ensure a selectivity to oxygenate of 45%-55%. The third stream 15 is then conveyed into the product separation unit 87 where it can be processed to recover among other a methanol stream 31 and/or, in a preferred embodiment, to valorise its different components, such as water, carbon dioxide and/or carbon monoxide, and subsequently increases the conversion of methane and the yield in methanol of the overall process.

Advantageously, step (b) of providing a second stream 13 which is an oxygen-rich stream is performed at the start of the process to initiate the conversion of methane into methanol and is stopped as soon as step (e) recycles at least 50 vol.% of the oxygen-rich stream. The second stream 13 is a start-up feed of oxygen. More preferably, step (b) of providing a second stream which is an oxygen-rich stream is performed at the start of the process to initiate the conversion of methane into methanol and is stopped as soon as step (e) recycles the whole of the oxygen-rich stream. With preference, said second stream 13 has a molar flow rate, considering a methane feedstock flowrate of 175 t/h, ranging between 250 t/h and 300 t/h, more preferably between 260 t/h and 290 t/h, even more preferably between 270 t/h and 280 t/h. Alternatively (not shown), a stream of water is directed into a water electrolysis unit of the installation to produce an oxygen stream and a hydrogen stream wherein the oxygen stream initiates the conversion of methane into methanol.

Separation of water and co-production of hydrogen

The product separation unit 87 can comprise one or more distillation columns, such as a water separator 19 disposed at the inlet of the product separation unit 87.

The third stream 15 can be advantageously directed into one or more heat exchangers 17 before entering the product separation unit 87, so that one or more temperature adjusting steps can be performed onto the third stream 15 before it enters the product separation unit 87. The third stream 15 is thus directed into the water separator 19 working at a temperature below 80°C, to recover a fourth stream 49 comprising methanol and a water stream 21. The fourth stream 49 comprising methanol may also comprise one or more of formaldehyde, carbon dioxide, carbon monoxide, hydrogen and unreacted methane. The fourth stream 49 comprising methanol is a gaseous stream. Optionally, one or more of methanol, formaldehyde, carbon dioxide, carbon monoxide, hydrogen and unreacted methane can be recovered in additional distillation columns (61, 23, 29) or specific separators such as a C0₂-separator 53 of the product separation unit 87 (see the section below about the recovery of the products).

At least a part of the water stream 21 can be then conveyed into a water electrolysis unit 89, which comprises an electrolysis cell 37. However, to recover any products that can have been solubilized into the water stream 21 (for example any oxygenates such as formaldehyde and/or methanol) and/or to improve the working of the water electrolysis unit 89, the water stream 21 is preferably subjected to additional separation step using distillation (see below). For example, electrolysis cell 37 can be any state-of-the-art water electrolyser, such as an alkaline electrolysis cell, a proton-exchange membrane electrolysis cell or a solid oxide electrolysis cell. In there, the electrolysis reaction of water can be carried out under pressure conditions ranging from 0.1 MPa to 20.0 MPa, preferably from 1.0 MPa to 15.0 MPa, more preferably from 5.0 MPa to 10.0 MPa, and under temperature conditions ranging from 50°C and 1000°C, preferably from 100°C to 800°C, more preferably from 200°C to 600°C. Thus, thanks to an energy stream 39, consisting preferentially of non-fossil renewable energy (i.e., green electricity coming from solar energy and/or wind energy), water is split into an oxygen stream 95 and a hydrogen stream (43, 47). The oxygen stream 95 is recycled in the second stream 13 and therefore directed to the methane conversion unit 85. This recycling loop increases the efficiency of the process and limits the costs since the oxygen needed to perform the oxidation reaction is generated from one of the products (namely water) generated in the DMTM reactor 11.

Before being conveyed into electrolysis cell 37, the water stream 21 can be directed to one or more heat exchangers 41 to be subjected to one or more temperature adjusting steps to reach the required level of temperature for the electrolysis reaction.

The hydrogen stream 43 can be optionally dried in a dryer system 45 to produce a dried hydrogen stream 47. For example, the dryer system 45 is a desiccant. For example, the desiccant can be a molecular sieve, such as one or more zeolite from the LTA family. Among the LTA family, zeolites from LTA-3A, LTA-4A and/or LTA-5A can be selected.

To recover the methanol generated in the DMTM reactor 11, the fourth stream 49 recovered from the water separator 19 can be further separated, for example by one or more separation steps that can be carried out by distillation. A methanol stream 31 can thus be isolated among other interesting products (see below section about the separation and recovery of methanol).

In accordance with the embodiment illustrated in figure 1 , the fourth stream 49 further comprises unreacted methane, and the process further comprises one or more further separation step. The one or more further separation steps preferably include a liquid-gas separation step conducted on the fourth stream 49 using a second distillation column 61 to recover a liquid stream 63 comprising at least methanol and a gaseous stream 65 comprising at least unreacted methane, and a step of recycling the unreacted methane into the first stream (1, 7). The gaseous stream (65) comprising at least unreacted methane further comprise one or more selected from carbon dioxide, carbon monoxide and hydrogen, and the step of recycling the unreacted methane into the first stream (1 , 7) comprises a sub-step of separating unreacted methane from the one or more selected from carbon dioxide, carbon monoxide and hydrogen to provide an unreacted methane stream 71 and recycling the unreacted methane stream 71 into the first stream (1 , 7).

In accordance with the embodiment illustrated in figure 2, the fourth stream 49 is treated to remove CO2 before performing the one or more further separation step, and preferably before performing the liquid-gas separation step conducted on the fourth stream 49 using a second distillation column 61 to recover a liquid stream 63 comprising at least methanol and a gaseous stream 65 comprising at least unreacted methane.

Separation of carbon oxides and valorisation into methanol In the preferred embodiment, carbon oxides, such as carbon dioxide and/or carbon monoxide, present in the fourth stream 49 can be further extracted and reused to improve the methanol production and subsequently increase the overall yield of the present process.

The fourth stream 49 is thus advantageously routed to a CC>2-separator 53, disposed downstream of the water separator 19 in the product separation unit 87. The CC separator 53 is advantageously placed upstream of the additional distillation columns (61, 23, 29). For example, the CC>₂-separator53 can be an absorption column using amine solvents. Optionally, one or more heat exchangers 51 are disposed between the water separator 19 and the 00₂- separator 53 so that one or more temperature adjusting steps can be performed onto the fourth stream 49 before it reaches the C0₂-separator 53. The C0₂-separator can advantageously comprise a C02-amine absorber that works at a temperature ranging between 30°C and 50°C, preferably between 35°C and 45°C and/or at a pressure ranging between 0.5 MPa and 20.0 MPa, preferably between 1.0 MPa and 10.0 MPa. The amine solvent of the C02-separator can optionally be regenerated through an amine regenerator that advantageously can work at a temperature comprised between 110°C and 130°C, preferably between 115°C and 125°C and/or at a pressure ranging between 0.10 MPa and 0.20 MPa, preferably between 0.12 MPa and 0.18 MPa. A CC>2-containing stream 55 can thus be recovered from the CC>2-separator 53. The remaining stream 57 exiting the CC>2-separator 53 comprises preferably less than 3.0 mol.% of carbon dioxide based on the total molar content of said remaining stream 57, preferably less than 2.0 mol.%, more preferably less than 1.0 mol.%, even more preferably less than 0.1 mol%, most preferably devoid of carbon dioxide. Said remaining stream 57 comprises at least methanol and comprises optionally one or more selected from formaldehyde carbon monoxide, hydrogen, unreacted methane. The remaining stream 57 can be further separated, for example by one or more separation steps that can be carried out by distillation in one or more additional separation columns (61, 23, 29). Optionally, one or more heat exchangers 59 are disposed between the C0₂-separator 53 and the one or more additional distillation columns (61, 23, 29), so that one or more temperature adjusting steps can be performed onto the remaining stream 57 before it reaches the one or more additional distillation columns (61 , 23, 29). A methanol stream 31 can thus be isolated (see below section about the separation and recovery of methanol).

A second distillation column 61 of the product separation unit 87 is preferably placed downstream of the CC>2-separator 53 (i.e. , the first distillation column). The second distillation column 61 is advantageously working at a temperature ranging between -80°C to -20°C, preferably between -70°C and -30°C, and/or at a pressure ranging between 2.5 MPa and 3.5 MPa, preferably between 2.7 MPa and 3.3 MPa. The remaining stream 57 is separated into a gaseous stream 65 and a liquid stream 63. The gaseous stream 65 comprises carbon monoxide, hydrogen and unreacted methane. After advantageously conveying the gaseous stream 65 to one or more heat exchangers 67 so that one or more temperature adjusting steps can be performed onto the gaseous stream 65, the gaseous stream 65 can be conveyed to a methane separator 69.

A methane stream 71 can be thus recovered and is optionally directed into the methane conversion unit 85 (not shown) and/or into the compressor 3 (not shown) and/or mixed with the first stream 1 comprising methane as shown in figures 1 and 2. This allows recycling the methane which has not been converted into methanol within the DMTM reactor 11.

From the methane separator 69, it is also possible to recover a stream 73 comprising carbon monoxide and/or hydrogen.

The CO2 stream 55 and/or the stream 73 comprising carbon monoxide and/or hydrogen can exit the product separation unit 87 and be conveyed into a carbon oxides valorisation unit 91.

In the carbon oxides valorisation unit 91 , the CO2 stream 55 and/or the stream 73 comprising carbon monoxide and/or hydrogen are advantageously combined to form a carbon oxides stream 77 that can be preferably directed into a compressor 75. The compressor 75 allows to pressurize the CO2 stream 55 and/or the stream 73 comprising carbon monoxide and/or hydrogen at a pressure ranging between 6.0 MPa and 8.0 MPa, preferably between 6.5 MPa and 7.5 MPa. Therefore, the carbon oxides stream 77 exiting the compressor 75 can be preferably pressurized.

The carbon oxides stream 77, comprising carbon dioxide, carbon monoxide and/or hydrogen, can be then directed into a syngas-to-methanol reactor 81 within the carbon oxides valorisation unit 91. Optionally, the carbon oxides stream 77 can be conveyed into one or more heat exchangers 79, so that one or more temperature adjusting steps can be carried out for the carbon oxides stream 77 to reach a temperature comprises between 200°C and 250°C, preferably between 210°C and 240°C, before it reaches the syngas-to-methanol reactor 81.

The syngas-to-methanol reactor 81 is provided with one or more catalysts, preferably selected from the list comprising indium oxide catalyst, Cu-Zn/AhCh, Cu-Zn0-Ga₂0₃/SiC>₂, Cu-ZnO- Al203/ZrC>2, ZnO, Au/ZnO, Au/Fe2C>3, AU/T1O2, Au/ZrC>2, Au/l_a2C>3, Au/ZnFe2C>4, Fe2C>3, Au/Fe2C>3, Cu/ZnO, CeC>2, T1O2, ZrC>2, La2C>3, ZnFe2C>3, and a combination thereof, preferably indium oxide catalyst or Cu-ZnO-AhCh/ZrC^. In the case where the indium oxide catalyst is selected, said indium oxide catalyst is preferably under the form of Ih2q3. Indium oxide catalysts, upon standard reaction conditions, are not deactivated when being in presence of a high concentration of carbon dioxide. Advantageously, indium oxide catalyst can further comprise a catalyst support. Indium oxide in the form of Ih2q3 deposited on a catalyst support and their method of preparation are known and described for example in WO2017/118572 and in WO2017/118573 which are incorporated by reference.

In an embodiment, the catalyst support of the catalyst comprises at least one selected from silica (S1O2), alumina (AI2O3), gallium oxide (Ga2C>3), cerium oxide (CeC>2), vanadium oxide (V₂O₅), chromium oxide (C^Ch), zirconium dioxide (ZrC>2), titanium dioxide ( PO2), magnesium oxide (MgO), zinc oxide (ZnO), tin oxide (SnC>2), carbon black (C), and combinations thereof. Preferably, the catalyst support of the catalyst comprises at least one selected from zinc oxide (ZnO), zirconium dioxide (Zr0₂)and titanium dioxide ( PO2) ora combination thereof; and more preferably the catalyst support of the catalyst is or comprises zirconium dioxide. When the catalyst support comprises zirconium dioxide (Zr02), the zirconium dioxide can be monoclinic, tetragonal, or cubic.

In an embodiment, the catalyst support of the catalyst is zirconium dioxide or a combination of zirconium dioxide with another catalyst support in which zirconium dioxide is contained in an amount of at least 10 wt.%, preferably at least 50 wt.%, more preferably at least 80 wt.%, and even more preferably at least 90 wt.% based on the total weight of the catalyst support, the other catalyst support is selected from silica (S1O₂), alumina (AI₂O₃), gallium oxide (Ga₂C>₃), cerium oxide (Ce0₂), vanadium oxide (V₂O₅), chromium oxide (( 203), titanium dioxide ( PO₂), magnesium oxide (MgO), zinc oxide (ZnO), tin oxide (Sn0₂), carbon black (C), and combinations thereof; preferably the other catalyst support is selected from zinc oxide (ZnO), titanium dioxide ( PO₂), and combinations thereof.

The surface area (i.e BET surface area) of the one or more catalysts provided in the syngas- to-methanol reactor 81 is determined by N2 sorption analysis according to ASTM D3663 - 03 and is advantageously in the range of about 5 m²g ¹ to about 400 m² g^_1, such as from 30 m² g ¹ to about 200 m² g^_1.

With preference, the catalyst is or comprises an indium oxide catalyst in the form of particles having an average crystal size of less than 20 nm as determined by X-Ray Diffraction, preferably less than 15 nm, more preferably less than 12 nm, even more preferably less than 10 nm. The catalyst comprises an active phase and the active phase can be combined with a catalyst support or other support medium through, for example, impregnation, such that the catalyst can be coated on, deposited on, impregnated on or otherwise placed adjacent to the catalyst support. For example, a supported catalyst can be synthesized by an impregnation step followed by a calcination step. The catalyst can be provided in technical shapes such as extrudates, granules, spheres, monoliths, or pellets and might contain additives such as lubricants, peptizers, plasticizers, porogens, binders, and/or fillers.

In a preferred embodiment, when the catalyst is indium oxide catalyst, the catalyst is or comprises indium oxide in the form of Ih2q3 and at least one metal, wherein both indium oxide and the at least one metal are deposited on a support. With preference, at least one metal is selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), platinum (Pt), copper (Cu), nickel (Ni), cobalt (Co), gold (Au), iridium (Ir), and any combination thereof; preferably a metal selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), platinum (Pt), copper (Cu), and any combination thereof; more preferably, a metal selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), platinum (Pt), and any combination thereof; even more preferably, a metal selected from palladium (Pd) and/or platinum (Pt), and most preferably the metal is palladium (Pd).

Wth preference, said at least one metal is in an oxidized form.

Wth preference, the average particle size of the one or more metal phase is less than 5 nm as determined by Scanning Transmission Electronic Microscopy - Energy-Dispersive X-Ray Spectroscopy (STEM-EDX), more preferably less than 4 nm, even more preferably less than 2 nm.

In an embodiment, the catalyst is a calcined supported catalyst and comprises from 0.01 to 10 wt.% of the at least one metal based on the total weight of the calcined supported catalyst.

Wth preference, the catalyst is a calcined supported catalyst and comprises at least 0.05 wt.% of the at least one metal based on the total weight of the calcined supported catalyst, preferably at least 0.1 wt.%, more preferably at least 0.3 wt.%, even more preferably at least 0.5 wt.%, and most preferably at least 0.7 wt.%.

Wth preference, the catalyst is a calcined supported catalyst and comprises at most 10.0 wt.% of the at least one metal based on the total weight of the calcined supported catalyst, preferably at most 7.0 wt.%, more preferably at most 5.0 wt.%, even more preferably at most 2.0 wt.%, and most preferably at most 1.0 wt.%. In one embodiment, said catalyst is or comprises indium oxide in the form of Ih2q3 and is optionally mixed with at least one alkaline earth metal, wherein both indium oxide and the at least one alkaline earth metal are deposited on a support.

With preference, said at least one alkaline earth metal is selected from beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), and any combination thereof.

Wth preference, the catalyst is a calcined supported catalyst and comprises from 0.01 to 10.0 wt.% of at least one alkaline earth metal based on the total weight of the calcined supported catalyst.

Advantageously, the catalyst is a calcined supported catalyst and comprises at least 0.05 wt.% of the at least one alkaline earth metal based on the total weight of the calcined supported catalyst, preferably at least 0.1 wt.%, more preferably at least 0.3 wt.%, even more preferably at least 0.5 wt.%, and most preferably at least 0.7 wt.%.

Advantageously, the catalyst is a calcined supported catalyst and comprises at most 10.0 wt.% of the at least one alkaline earth metal based on the total weight of the calcined supported catalyst, preferably at most 7.0 wt.%, more preferably at most 5.0 wt.%, even more preferably at most 2.0 wt.%, and most preferably at most 1.0 wt.%.

Before reaction, the one or more catalysts provided in the syngas-to-methanol reactor 81 can be activated in situ by raising the temperature to at least 260°C in a flow of a gaseous feed stream for activation selected from inert gases, hydrogen, carbon monoxide, carbon dioxide or a mixture thereof.

The reaction conditions implemented within the syngas-to-methanol reactor 81 can advantageously comprise a molar ratio CO/CO2 ranging between 0:1 (absence of carbon monoxide) and 2:1 , preferably between 0.5:1 and 1.5:1; a temperature comprised between 200°C and 250°C, preferably between 210°C and 240°C; and/or a pressure ranging between 6.0 MPa and 8.0 MPa, preferably between 6.5 MPa and 7.5 MPa.

In a preferred embodiment, the hydrogen stream 47 exiting the water electrolysis unit 89 can be used as the source of hydrogen to the conversion reaction occurring within the syngas-to- methanol reactor 81 or more preferably as a complementary source of hydrogen in case of the carbon oxides stream 77 already comprises hydrogen. Alternatively, in a less preferred embodiment (not shown), an external source of hydrogen can be used to feed the syngas-to- methanol reactor 81. The molar ratio H2/(CO+CC>2) in the syngas-to-methanol reactor 81 is thus ranging between 3 and 15, preferably between 5 and 13, more preferably between 7 and 11.

The stream 83 exiting the syngas-to-methanol reactor 81 comprises therefore at least methanol and water, and can also comprise unreacted carbon dioxide, unreacted carbon monoxide and/or unreacted hydrogen. To increase the efficiency of the overall process, stream 83 can be directed into the product separation unit 87, in particular into the water separator 19, or as shown in figures 1 and 2, be mixed with the third stream 15 exiting from the DMTM reactor 11. With this configuration, the carbon oxides, namely carbon dioxide and carbon monoxide, formed in the methane conversion unit 85 in the absence of a catalyst, have not been wasted because they have been further converted into methanol thanks to the use of one or more catalysts. Furthermore, the water exiting the DMTM reactor 11 has also been recovered and split into hydrogen within the water electrolysis unit 89 that has not been wasted either but used as a feed to the syngas-to-methanol reactor 81.

Separation and recovery of the methanol

The remaining stream 57, which comprises at least carbon monoxide, hydrogen, unreacted methane, methanol and formaldehyde, can be further separated, for example by one or more separation steps that can be carried out by distillation.

The liquid stream 63 recovered from the remaining stream 57 comprises methanol and optionally formaldehyde.

The liquid stream 63 can be combined with at least a part of the water stream 21 exiting the water separator 19, preferably in the third distillation column 23 which is downstream of the second distillation column 61. This allows the recovery of any oxygenates, such as formaldehyde and/or methanol, which have been solubilized within the water. This configuration implying the combination of at least a part of or preferably the totality of the water stream 21 with the liquid stream 63 is, therefore, an advantageous way to avoid losing oxygenates in the present process. Additionally, this allows the water electrolysis unit to work better since the water stream 33 entering the water electrolysis unit 89 comprises in this case fewer impurities that could hamper the working of the water electrolysis unit 89.

The third distillation column 23 allows the separation of formaldehyde, when present, from the liquid stream 63, to recover a formaldehyde stream 25 and a stream 27 comprising methanol and preferably water. To do so, the third distillation column 23 is advantageously working at a temperature ranging between -20°C and -40°C, preferably between -25°C and -35°C; and/or at a pressure ranging between 0.1 MPa and 1.0 MPa, preferably between 0.3 MPa and 0.8 MPa.

Stream 27 comprising methanol and preferably water is then directed into a fourth distillation column 29, in which a methanol stream 31 can be recovered. To do so, the fourth distillation column 29 is advantageously working a temperature ranging between 60°C and 80°C, preferably between 65°C and 75°C; and/or at a pressure ranging between 0.1 MPa and 1.0 MPa, preferably between 0.3 MPa and 0.8 MPa.

The remaining water stream 33 exiting the fourth distillation column can be conveyed out of the product separation unit 87 towards the water electrolysis unit 89 to feed the electrolysis cell 37, optionally through one or more heat exchangers 35 so that one or more adjusting steps can be performed onto the remaining water stream 33 before it reaches the electrolysis cell 37.

Test and determination methods

The energy efficiency (EE) is defined as the ratio between the heat value of the products related to the sum of the heat value of the reactants and the net energy consumed in the process.

The carbon efficiency (CE) is defined as the molar ratio between the amount of carbon products related to the carbon reactant consumed.

If we consider all the valorizable products that can be generated from the process of the present disclosure, EE and CE are written as equations (VII) and (VIII), where HHV is the higher heating value, F is the molar flow rate, and w_c is the carbon molar fraction.

Example

The advantages of the present disclosure are illustrated by the following examples. However, it is understood that the disclosure is by no means limited to specific examples. T able 1 shows the results in term of molar flow rate obtained via a simulation thanks to ASPEN PLUS V9 software between installation devoid of water electrolysis unit and installations according to the disclosure, namely comprising at least one water electrolysis unit.

Table 1 : Molar flow rate (t/h) of four different installations for carrying out a process for converting a stream comprising methane into methanol

* A start-up feed of oxygen is provided, corresponding to a molar flow rate of 271 t/h, to launch the process. This start-up feed of oxygen is provided as the second stream 13 of the process of the disclosure.

** recycled from the products Table 1 shows that the addition of a water electrolysis unit 89 in an installation of the type shown in figure 1 allows increasing significantly the energy efficiency by producing hydrogen. The energy efficiency has been determined to be 70%. It appears indeed that the hydrogen has a heating value of 142 MJ/kg, which is about three times higher than the heating values of the methane feedstock which is 56 MJ/kg. Besides the production of hydrogen, the water electrolysis unit 89 also produced oxygen which can be recycled into the second stream 13, subsequently replacing the need for the start-up feed. Furthermore, the addition of a carbon oxide valorisation unit 91 to an installation already comprising a water electrolysis unit 89 has allowed establishing an installation of the type shown in figure 2. Such installation has achieved not only an elevated energy efficiency (72%) compared to the one devoid of water electrolysis unit but also a very high carbon efficiency (85%).

Claims

1. A process for converting a stream comprising methane into methanol, said process being characterized in that it comprises the following steps: a) providing a first stream (1 ; 7) comprising methane; b) providing a second stream (13) which is an oxygen-rich stream; c) contacting said first stream (1, 7) with said second stream (13) under oxidation reaction conditions to obtain a third stream (15) comprising at least methanol and water; d) separating water from said third stream (15) to recover a water stream (21; 33) and a fourth stream (49) comprising methanol; e) subjecting at least a part of said water stream (21; 33) recovered from step (d) to an electrolysis step to produce an oxygen stream (95) and a hydrogen stream (43; 47), wherein the oxygen stream (95) is recycled into the second stream (13); f) optionally, recovering a methanol stream (31) from said fourth stream (49).

2. The process according to claim 1 , characterized in that step (c) is carried out in the absence of a catalyst.

3. The process according to claim 2, characterized in that the oxidation reaction conditions of step (c) comprise a temperature ranging between 300°C and 600°C.

4. The process according to claim 2 or 3, characterized in that the oxidation reaction conditions of step (c) comprise a pressure ranging from 4.0 MPa to 20.0 MPa.

5. The process according to any one of claims 2 to 4, characterized in that the oxidation reaction conditions of step (c) comprise oxygen to methane ratio ranging between 0.02:1 and 0.20:1, preferably between 0.03:1 and 0.06:1.

6. The process according to any one of claims 1 to 5, characterized in that the step (e) of subjecting said water stream (21 ; 33) from step (d) to an electrolysis step is carried out under a temperature ranging between 50°C and 1000°C.

7. The process according to any one of claims 1 to 6, characterized in that the step (e) of subjecting said water stream (21 ; 33) from step (d) to an electrolysis step is carried out under a pressure ranging between 0.1 MPa and 20.0 MPa.

8. The process according to any one of claims 1 to 7, characterized in that the fourth stream (49) further comprises carbon dioxide and the process further comprises a step of recovering said carbon dioxide conducted after step (d) to recover a carbon oxides stream (77) comprising at least carbon dioxide and a remaining stream (57) comprising at least methanol.

9. The process according to claim 8, characterized in that it further comprises a step of contacting said carbon oxides stream (77) with a hydrogen stream (47) in presence of one or more catalysts under reaction conditions to produce methanol and water.

10. The process according to claim 9, characterized in that said hydrogen stream (47) is the hydrogen stream produced in step (e).

11. The process according to claim 9 or 10, characterized in that the methanol and water produced in said additional step are recycled with the third stream (15) obtained in step (c).

12. The process according to any one of claims 9 to 11, characterized in that said one or more catalysts of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) are one or more catalysts selected from the list comprising indium oxide catalyst, Cu-Zn/AhCh, Cu-Zn0-Ga203/SiC>2, Cu-ZnO-AhCh/ZrC^, ZnO, Au/ZnO, Au/Fe2C>3, AU/T1O2, Au/ZrC>2, Au/l_a2C>3, Au/ZnFe2C>4, Fe2C>3, Au/Fe2C>3, Cu/ZnO, CeC>2, T1O2, ZrC>2, La2C>3, ZnFe2C>3, and a combination thereof.

13. The process according to any one of claims 9 to 12, characterized in that said one or more catalysts of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) are or comprise indium oxide catalyst.

14. The process according to any one of claims 9 to 13, characterized in that said one or more catalysts of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) are or comprise Cu-ZnO-AhCh/ZrC^.

15. The process according to any one of claims 9 to 14, characterized in that said one or more catalysts of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) are or comprise a mixture of indium oxide catalyst and Cu- Zn0-Al203/ZrC>2.

16. The process according to any one of claims 9 to 15, characterized in that the reaction conditions of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) comprises a molar ratio CO/CO2 ranging between 0:1 and 2:1.

17. The process according to any one of claims 9 to 16, characterized in that the reaction conditions of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) comprises a molar ratio H2/(CO+CC>2) ranging between 3 and 15.

18. The process according to any one of claims 9 to 17, characterized in that the reaction conditions of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) comprises a temperature ranging between 200°C and 250°C.

19. The process according to any one of claims 9 to 18, characterized in that the reaction conditions of the step of contacting said carbon oxides stream (77) with a hydrogen stream (47) comprises a pressure ranging between 6.0 MPa and 8.0 MPa.

20. The process according to any one of claims 1 to 19, characterized in that the fourth stream (49) and the optional remaining stream (57) comprising methanol further comprises unreacted methane, and the process further comprises a liquid-gas separation step conducted on the fourth stream (49) or the remaining stream (57) when present, to recover a liquid stream (63) comprising at least methanol and a gaseous stream (65) comprising at least unreacted methane, and a step of recycling the unreacted methane into the first stream (1, 7).

21. The process according to claim 20, characterized in that the gaseous stream (65) comprising at least unreacted methane further comprises one or more selected from carbon dioxide, carbon monoxide and hydrogen, and the step of recycling the unreacted methane into the first stream (1, 7) comprises a sub-step of separating unreacted methane from the one or more selected from carbon dioxide, carbon monoxide and hydrogen to provide an unreacted methane stream (71) and recycling the unreacted methane stream (71) into the first stream (1, 7).

22. The process according to any one of claims 1 to 21 , characterized in that step (a) of providing a first stream (1; 7) comprising methane comprises providing a natural gas comprising methane at a content of at least 75 mol.% of the total molar content of said natural gas.

23. The process according to any one of claims 1 to 22, characterized in that step (a) of providing a first stream (1; 7) comprising methane comprises a sub-step of purifying the natural gas to remove sulphur.

24. The process according to any one of claims 1 to 23, characterized in that step (a) of providing a first stream (1; 7) comprising methane comprises a sub-step of purifying the natural gas to remove nitrogen.

25. Installation for carrying out the process for converting a stream comprising methane into methanol according to any one of claims 1 to 24, said installation being characterized in that it comprises

- a methane conversion unit (85);

- a product separation unit (87); and

- a water electrolysis unit (89); wherein the methane conversion unit (85), the product separation unit (87) and the water electrolysis unit (89) are fluidically connected in series, the product separation unit (87) being downstream of said methane conversion unit (85) and upstream of said water electrolysis unit (89); and wherein said product separation unit (87) comprises a first distillation column (19) in connexion with a line to conduct a water stream (21) exiting from said first distillation column (19) to said water electrolysis unit (89), and another line to recover a fourth stream (49) comprising at least methanol exiting from said first distillation column (19).

26. Installation according to claim 25, characterized in that the product separation unit (87) comprises at least one additional distillation column (31, 23, 29) arranged downstream the first distillation column (19) to perform one or more product separations on the fourth stream (49).

27. Installation according to claim 25 or 26, characterized in that said installation further comprises within the product separation unit (87) a CC>2-separator (53).

28. Installation according to claim 27, characterized in that said installation further comprises a carbon oxides valorisation unit (91) disposed downstream of said CO2- separator (53), the installation comprising a line directing a CO2 stream (55) exiting said CC>2-separator (53) to said carbon oxides valorisation unit (91).

29. Installation according to any one of claims 25 to 28, characterized in that said installation further comprises a methane separator (69) within the product separation unit (87).

30. Installation according to claim 29, characterized in that the installation comprises a line recycling a methane stream (71) exiting said methane separator (69) to said methane conversion unit (85).

31. Installation according to claim 29 or 30, characterized in that the installation further comprises a carbon oxides valorisation unit (91) disposed downstream of said methane separator (69), the installation comprising a line directing a stream (53) comprising carbon monoxide and/or hydrogen exiting said methane separator (69) to said carbon oxides valorisation unit (91).

32. Installation according to any one of claims 25 to 31, wherein the installation comprises a carbon oxides valorisation unit (91) disposed downstream of the product separation unit (87), characterized in that the water electrolysis unit (89) comprises a line to conduct a hydrogen stream (47) exiting said water electrolysis unit (89) to said carbon oxides valorisation unit (91).

33. Installation according to any one of claims 25 to 32, wherein the installation comprises a carbon oxides valorisation unit (91) disposed downstream of the product separation unit (87), characterized in that the carbon oxides valorisation unit (91) comprises a syngas-to-methanol reactor (81).

34. Installation according to claim 33, characterized in that said syngas-to-methanol reactor (81) comprises a line to conduct a stream (83) comprising at least methanol and/or water into the product separation unit (87).

35. Installation according to any one of claims 25 to 34, characterized in that said installation further comprises a pressurization unit (93) disposed upstream of said methane conversion unit (85).