Process for producing dimethyl ether and hydrogen from methane using solid metal oxide reactants

Abstract

The present invention relates to a process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the steps of: a) providing a gaseous feed stream comprising methane; b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX); c) separating the following from the effluent stream obtained in step b): (i) a methyl halide (MeX) stream; and (ii) a hydrogen halide (HX) stream; d) reacting the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s)) under reaction conditions effective to produce metal halide (MX) and dimethyl ether (DME); and e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising halogen reactants (X2).

Description

Technical Field

[0001] The present invention generally relates to processes and systems for producing dimethyl ether. Specifically, the present invention relates to processes and systems for producing dimethyl ether and hydrogen from a gas stream comprising or consisting of methane. The process is particularly characterized in that it utilizes a solid metal oxide reactant to form dimethyl ether and uses electrolysis to produce hydrogen gas. Background Art

[0002] Dimethyl ether (DME, CH3OCH3) is a colorless, non-toxic, non-corrosive, non-carcinogenic, and environmentally friendly chemical. DME has a boiling point of −25°C and is a gas under ambient conditions. However, DME can be easily handled as a liquid and stored in pressurized tanks, much like liquefied petroleum gas (LPG).

[0003] There are several applications for dimethyl ether, such as aerosols, propellants, chemical feedstocks, transportation fuels, or refrigerants. For example, today dimethyl ether is primarily used as an aerosol propellant in spray cans to replace banned CFC gases.

[0004] Another major application of DME is its use as a feedstock for the synthesis of other products such as dimethyl sulfate, methyl acetate and light olefins. DME can also be converted into acetic acid by carbonylation.

[0005] DME can also be used as a direct, cleaner fuel substitute for conventional diesel. In addition, DME is an important chemical intermediate in the production of widely used chemicals such as diethyl sulfate, methyl acetate or olefins. DME is considered an ultra-clean transportation fuel because it has a high cetane number (about 60), a low boiling point (-25°C) and a high oxygen content (35 wt%), which allows for rapid vaporization and higher combustion quality (smokeless operation and 90% less NOx emissions) compared to other alternative CO2-based fuels.

[0006] DME is usually produced via two main ways: the first is the indirect route, where DME is obtained by dehydration of methanol; the second is the direct route, where DME is produced directly from synthesis gas (hydrogen and carbon monoxide) in a single stage thanks to a bifunctional catalyst.

[0007] In the indirect pathway, the first step involves catalytic hydrogenation of synthesis gas to methanol (CO / CO + 3H → CH OH + H O), and the second step involves catalytic dehydration of methanol to produce DME (2CH OH → CH OCH + H O) on an acid catalyst. The major problem with this two-step DME synthesis is the strong thermodynamic limitations of the methanol synthesis step, which results in low gas conversion (15-25%) per pass, and therefore high recirculation rates, and high capital and operating costs. In addition, CO and CO are typically carried privately from the process for synthesizing methanol from synthesis gas as well as many other light and heavy by-products and methanol product. By-products are the result of the more complicated series of reactions that occur when the three reaction gases interact with each other and the catalytic surface. Most of the subsequent energy and costs in conventional methanol production plants are directed to these by-products because they must be separated from methanol product.

[0008] In the early 1990s, researchers began to investigate the direct synthesis of DME from syngas in a process where the methanol synthesis step was coupled in situ with the dehydration step in a single reactor ( The direct synthesis of DME allows for increased conversion levels in each step, up to 90%, which translates into significant savings in capital investment and production costs for DME. In fact, it is estimated that direct synthesis reduces DME production costs by 20-30% compared to the traditional two-step process.

[0009] However, direct synthesis of DME from syngas requires an efficient hybrid bifunctional catalytic system that combines a CO / CO2 hydrogenation function for methanol synthesis with an acidic function for methanol dehydration. Furthermore, the production of syngas itself typically involves cracking natural gas, which is very energy-intensive because the reaction is endothermic and typically occurs at high temperatures.

[0010] Document US2002 / 0198416 discloses a process in which methane reacts with bromine to form CH Br and HBr. These components then react with metal oxides to form a mixture of DME and metal bromide. In the first approach, CH Br and HBr react with the metal oxides in a converter to form DME. In the second approach, HBr first reacts with the metal oxides to form metal bromide and water. The metal bromide is then regenerated into the metal oxide in a regenerator. Then, water, CH Br and CH 4 are fed into a separator, where, after separation, CH Br is fed to a reactor to react with the regenerated metal oxide to produce DME.

[0011] Therefore, in view of the above, there is a need in the art to provide an improved process for producing DME. In particular, there is a need in the art for a DME production process that can operate under milder production process conditions, avoiding working at high temperatures and / or high pressures (which require excessive energy to maintain these temperatures and / or pressures).

[0012] There is also a need in the art for DME production processes involving lower CO / CO2 emissions.

[0013] There is a further need in the art for a DME production process that allows for the production of DME via different strategies, in particular not starting from a synthesis gas route.

[0014] It was therefore an object of the present invention to provide a process for producing DME which allows to meet at least some of the above-mentioned needs. Summary of the Invention

[0015] According to the present invention, an improved process for producing dimethyl ether and hydrogen from methane is provided.

[0016] In a first aspect, the present invention provides a process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the following steps:

[0017] a) providing a gaseous feed stream comprising methane;

[0018] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX), and hydrogen halide (HX), optionally polyhalogenated alkane, and optionally unreacted methane;

[0019] c) separating from the effluent stream obtained in step b) the following:

[0020] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0021] (ii) hydrogen halide (HX) stream;

[0022] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0023] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a stream of gaseous hydrogen (H2) and a stream comprising the halogen reactant (X2).

[0024] In particular, the present invention provides a process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the following steps:

[0025] a) providing a gaseous feed stream comprising methane;

[0026] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX), optionally polyhalogenated alkane, and optionally unreacted methane;

[0027] c) separating from the effluent stream obtained in step b) the following:

[0028] i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0029] ii) an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream;

[0030] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0031] e) decomposing said aqueous hydrogen halide (HX) stream or said hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2);

[0032] wherein in step c) the hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising said hydrogen halide with an aqueous absorbent or by distillation, thereby forming an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream, respectively.

[0033] In some embodiments, the process further comprises the step of separating the polyhalogenated alkanes formed in step b) from the effluent stream, preferably before separating the methyl halide (MeX) stream and the hydrogen halide stream from the effluent stream.

[0034] In some embodiments, the present invention provides a process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the steps of:

[0035] a) providing a gaseous feed stream comprising methane;

[0036] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX), and hydrogen halide (HX), polyhalogenated alkanes, and optionally unreacted methane;

[0037] c) separating from the effluent stream obtained in step b) the following:

[0038] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0039] (ii) a hydrogen halide (HX) stream; and

[0040] (iii) polyhalogenated alkane streams;

[0041] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0042] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a stream of gaseous hydrogen (H2) and a stream comprising the halogen reactant (X2).

[0043] In some embodiments, the polyhalogenated alkane comprises polyhalogenated methane and optionally polyhalogenated C 2+ Alkanes.

[0044] In some embodiments, the halogen reactant is selected from bromine (Br2), chlorine (Cl2), fluorine (F2), iodine (I2) and astatine (At2), and is preferably bromine (Br2).

[0045] In some embodiments, in step c), a hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising the hydrogen halide with an aqueous absorbent, preferably an aqueous hydrogen halide (HX) solution, thereby forming an aqueous hydrogen halide (HX) stream.

[0046] In some embodiments, C 2+ The alkyl monohalide is formed in step b).

[0047] In some embodiments, the process comprises separating the C formed in step b) of the process from the effluent stream. 2+ and preferably the process comprises separating the C alkyl monohalide formed in step b) from the effluent stream before separating the methyl halide (MeX) stream and the hydrogen halide stream from the effluent stream. 2+ Alkyl monohalides.

[0048] In some embodiments, the gaseous feed stream comprises at least 75.0 vol% methane, and preferably at least 80.0 vol% methane, preferably at least 85.0 vol% methane, preferably at least 90.0 vol% methane, preferably at least 95.0 vol% methane, preferably at least 98.0 vol% methane, preferably at least 99.0 vol% methane, preferably at least 99.9 vol% methane, based on the total volume of the gaseous feed stream.

[0049] In some embodiments, the gaseous feed stream used in step a) of the process is essentially free of sulfur species, for example, it contains less than 1.0 mol%, or less than 0.5 mol%, or less than 0.1 mol%, or less than 0.01 mol%, or less than 0.001 mol%, or less than 0.0001 mol%, or less than 0.00001 mol% of sulfur species.

[0050] In some embodiments, the solid metal oxide (MO) (s) ) is a metal hydroxide provided on a solid support, preferably wherein the support is a silica or alumina support.

[0051] In some embodiments, the process further comprises the following steps:

[0052] f) Regeneration of metal halide (MX) into metal oxide (MO) (s) ) and a halogen reactant (X2), and preferably by contacting the metal halide (MX) with steam and oxygen (O2) or air to form a metal oxide (MO) and a halogen reactant (X2).

[0053] In some embodiments, the process further comprises the step of returning the halogen reactant (X2) obtained in step e) and / or step f) to step b) of the process.

[0054] In some embodiments, the gaseous hydrogen (H2) stream produced in step e) comprises at least 90.0 mol%, eg, at least 95.0 mol%, or at least 99.0 mol%, or at least 99.5 mol%, or at least 99.9 mol% hydrogen.

[0055] In some embodiments, the process further comprises the following steps:

[0056] - removing unreacted methane from the dimethyl ether produced in step d), preferably by distilling the unreacted methane, and

[0057] - Optionally, the removed unreacted methane is recycled or fed into step a) and / or step b) of the process.

[0058] In a second aspect, the present invention provides a system for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising:

[0059] - a halogenation reactor (1) configured to react a gaseous feed stream comprising methane with at least one halogen reactant (X2) to form an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX) and optionally unreacted methane,

[0060] - a separation system (2) fluidly connected to the halogenation reactor (1) and configured to receive an effluent stream from the halogenation reactor (1) and configured to separate a hydrogen halide (HX) stream and a methyl halide (MeX) stream from the effluent stream;

[0061] - a dimethyl ether synthesis reactor (3) fluidically connected to the separation system (2) and configured to receive a methyl halide (MeX) stream from the separation system (2) and to combine the methyl halide (MeX) stream with a solid metal oxide (MO (s) ) to form a metal halide (MX) and dimethyl ether (DME); and

[0062] - an electrolysis unit (4) comprising at least one electrolysis cell and a power source for supplying electric current to the electrolysis cell, the electrolysis cell being fluidically connected to the separation system (2) and configured to receive a hydrogen halide (HX) stream and to decompose the hydrogen halide (HX) stream into a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2);

[0063] - a feed stream supply system (5) for supplying a gaseous feed stream comprising methane to the halogenation reactor (1);

[0064] - a halogen supply system (6) for supplying a halogen reactant (X2) to the halogenation reactor (1);

[0065] - an effluent collection system (10) configured to collect an effluent stream from the halogenation reactor (1) and to feed the collected effluent stream to the separation system (2);

[0066] - a dimethyl ether recovery system (7) configured to recover a stream containing dimethyl ether (DME) from the dimethyl ether synthesis reactor (3);

[0067] - a hydrogen recovery system (8) configured to recover a gaseous hydrogen (H2) stream from the electrolysis unit (4);

[0068] - a halogen recovery system (9) configured to recover the halogen reactant (X2) from the electrolysis unit (4);

[0069] - a hydrogen halide transfer system (12) configured to collect a hydrogen halide (HX) stream from the separation system (2) and supply the collected hydrogen halide (HX) stream to the electrolysis unit (4);

[0070] - a methyl halide transfer system (11) configured to collect a methyl halide (MeX) stream from the separation system (2) and supply the collected methyl halide (MeX) stream to a dimethyl ether synthesis reactor (3),

[0071] - Optionally, an absorbent supply line (17) for supplying an aqueous absorbent, preferably an aqueous hydrogen halide (HX) solution, to the separation system (2);

[0072] - optionally, a polyhalogenated alkane removal unit configured to receive the effluent stream from the halogenation reactor (1) and to remove polyhalogenated alkanes from the effluent stream; and,

[0073] - Optionally, C 2+ an alkyl monohalide removal unit configured to receive an effluent stream from the halogenation reactor (1) and remove C 2+ Alkyl monohalides.

[0074] The present process advantageously allows the production of a substantially pure dimethyl ether stream, e.g., substantially free of methanol (MeOH) and preferably other alcohols and / or ethers. The process of the present invention avoids any direct CO emissions and exhibits improved selectivity for the production of dimethyl ether. Furthermore, the present process also allows the production of a substantially pure stream of hydrogen gas as a by-product, which can be further used in numerous downstream applications.

[0075] The present invention also provides a process for producing dimethyl ether without the use of synthesis gas. According to the present invention, dimethyl ether and hydrogen are produced directly from methane, without the need to produce synthesis gas. The methane used in the process can come from renewable resources, making the production of dimethyl ether and the base chemicals produced from it more environmentally friendly.

[0076] The process is also highly efficient because it allows for the recycling (reuse) of reactants and reaction products in the same process, thereby reducing waste and / or pollution.

[0077] Furthermore, the process also allows the production of hydrogen by electrolytic decomposition of a hydrogen halide stream.Thus, at least part of the energy used in the present process is based on electrical energy, which can be obtained from renewable sources.

[0078] The independent and dependent claims set out particular and preferred features of the invention. Features in the dependent claims may be combined with features in the independent claim or other dependent claims as appropriate.

[0079] The present invention will now be further described. In the following paragraphs, different aspects of the present invention will be defined in more detail. Unless otherwise expressly stated, each aspect so defined can be combined with any other one or more aspects. In particular, any feature that is indicated as preferred or advantageous can be combined with any other one or more features that are indicated as preferred or advantageous. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 A process according to one embodiment of the invention and a system according to an embodiment of the invention are depicted.

[0081] Figure 2 A process according to another embodiment of the invention and a system according to an embodiment of the invention are depicted. DETAILED DESCRIPTION

[0082] In describing the present invention, the terms used should be interpreted in accordance with the following definitions, unless the context dictates otherwise.

[0083] Unless otherwise defined, all terms, including technical and scientific terms, used in disclosing the present invention have the meanings commonly understood by one of ordinary skill in the art to which the present invention belongs. Further guidance, including term definitions, is provided to better understand the teachings of the present invention.

[0084] In the following paragraphs, different aspects of the present invention will be defined in more detail. Unless otherwise expressly stated, each aspect so defined may be combined with any other aspect or aspects. In particular, any feature indicated as preferred or advantageous may be combined with any other feature or features indicated as preferred or advantageous.

[0085] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily all refer to the same embodiment, but may all refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, as will be apparent to those skilled in the art from this disclosure. Furthermore, while some embodiments described herein include some features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the invention and to form different embodiments, as will be appreciated by those skilled in the art.

[0086] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," or "containing," "contains," and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or process steps. It will be understood that the terms "comprising," "comprises," and "comprised of" as used herein include the terms "consisting of," "consists," and "consists of."

[0087] As used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, "a step" means one step or more than one step.

[0088] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0089] Numerical ranges expressed by endpoints include all integers and, where appropriate, fractions contained within the range (when referring to, for example, the number of elements, 1 to 5 may include 1, 2, 3, 4, and when referring to, for example, measurements, 1.5, 2, 2.75, and 3.80 may also be included). The expression of endpoints also includes the 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 subranges contained therein.

[0090] As used herein, the term "about" when referring to a measurable value (e.g., a parameter, amount, duration, etc.) is intended to encompass variations of the specified value, or + / - 10% or less, preferably + / - 5% or less, more preferably + / - 1% or less, as long as these variations are suitable for practicing the disclosed invention. It should be understood that the value to which the modifier "about" refers is itself also specifically and preferably disclosed.

[0091] The terms "wt%", "vol%" or "mol%" refer to the weight percent of a component, the volume percent of a component or the mole percent of a component, respectively, based on the total weight, total volume, or total moles including the component.

[0092] When describing the present invention, the terms used should be interpreted in accordance with the following definitions, unless the context dictates otherwise.

[0093] Whenever the term "substituted" is used herein, it is intended to indicate that one or more hydrogens on the atom indicated by the expression "substituted" are replaced with a group selected from the group indicated, provided that the normal valence of the indicated atom is not exceeded and that the substitution produces a chemically stable compound, i.e., a compound sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture.

[0094] The term "alkyl" as a group or part of a group refers to a group of formula C n H 2n+1 wherein n is a number greater than or equal to 1. The alkyl group may be linear or branched and may be substituted as described herein. Generally, the alkyl groups of the present invention contain 1 to 20 carbon atoms, preferably 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1, 2, 3, 4, 5, 6 carbon atoms. When a subscript is used after a carbon atom herein, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term "C 1 -20 "Alkyl", as a group or part of a group, refers to a group of formula -C n H 2n+1 wherein n is a number from 1 to 20. Thus, for example, C 1-20Alkyl groups include all linear or branched alkyl groups having 1 to 20 carbon atoms and thus include, for example, methyl, ethyl, n-propyl, isopropyl, 2-methylethyl, butyl and its isomers (e.g., n-butyl, isobutyl, and tert-butyl); pentyl and its isomers, hexyl and its isomers, heptyl and its isomers, octyl and its isomers, nonyl and its isomers, decyl and its isomers, undecyl and its isomers, dodecyl and its isomers, tridecyl and its isomers, tetradecyl and its isomers, pentadecyl and its isomers, hexadecyl and its isomers, heptadecyl and its isomers, octadecyl and its isomers, etc. For example, C 1-10 Alkyl includes all linear or branched alkyl groups having 1 to 10 carbon atoms and thus includes, for example, methyl, ethyl, n-propyl, isopropyl, 2-methylethyl, butyl and its isomers (e.g., n-butyl, isobutyl and tert-butyl); pentyl and its isomers, hexyl and its isomers, heptyl and its isomers, octyl and its isomers, nonyl and its isomers, decyl and its isomers, etc. For example, C 1-6 Alkyl groups include all linear or branched alkyl groups having 1 to 6 carbon atoms, and thus include, for example, methyl, ethyl, n-propyl, isopropyl, 2-methylethyl, butyl and its isomers (e.g., n-butyl, isobutyl, and tert-butyl); pentyl and its isomers, hexyl and its isomers, etc. In some embodiments, non-limiting examples of alkyl groups include, for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, 2,2-dimethyl-propyl, hexyl, 2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3-pentyl, 2-methyl-2-hexyl, octyl, 4-methyl-3-heptyl, nonyl, decyl, undecyl, and dodecyl.

[0095] As used herein and unless otherwise indicated, the term "halo" or "halogen" as a group or part of a group refers collectively to any atom selected from fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At).

[0096] Preferred statements (features) and embodiments and uses of the present invention are described below. Unless otherwise expressly stated to the contrary, each statement and embodiment of the invention so defined may be combined with any other statement and / or embodiment. In particular, any feature indicated as preferred or advantageous may be combined with any other feature or features or statements indicated as preferred or advantageous. To this end, the present invention is particularly captured (covered) by one or more of the following numbered statements and embodiments and any one or any combination of any other aspects and / or embodiments.

[0097] 1. A process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the following steps:

[0098] a) providing a gaseous feed stream comprising methane;

[0099] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX), optionally polyhalogenated alkane, and optionally unreacted methane;

[0100] c) separating from the effluent stream obtained in step b) the following:

[0101] i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0102] ii) hydrogen halide (HX) stream;

[0103] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0104] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2).

[0105] 2. A process according to statement 1, wherein the process comprises the step of recovering a stream comprising dimethyl ether and optionally unreacted methane after step d).

[0106] 3. A process according to statement 1 or 2, wherein the process further comprises the step of separating the polyhalogenated alkanes formed in step b) from the effluent stream, preferably before separating the methyl halide (MeX) stream and the hydrogen halide stream from the effluent stream.

[0107] 4. A process for producing dimethyl ether (DME) and hydrogen (H2) from methane, preferably a process according to any one of statements 1 to 3, comprising the following steps:

[0108] a) providing a gaseous feed stream comprising methane;

[0109] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX), polyhalogenated alkanes, and optionally unreacted methane;

[0110] c) separating from the effluent stream obtained in step b) the following:

[0111] i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0112] ii) a hydrogen halide (HX) stream; and

[0113] iii) a polyhalogenated alkane stream;

[0114] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0115] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a stream of gaseous hydrogen (H2) and a stream comprising the halogen reactant (X2).

[0116] 5. A process according to statement 4, wherein the process comprises the step of recovering a stream comprising dimethyl ether and optionally unreacted methane after step d).

[0117] 6. A process according to any one of statements 1 to 5, wherein the polyhalogenated alkanes comprise polyhalogenated methanes and optionally polyhalogenated C 2+ Alkanes.

[0118] 7. A process according to any one of statements 1 to 6, wherein the halogen reactant is selected from bromine (Br2), chlorine (Cl2), fluorine (F2), iodine (I2) and astatine (At2).

[0119] 8. A process according to any of the preceding statements, wherein the halogen reactant is bromine (Br2).

[0120] 9. The process according to any of the preceding statements, wherein steps b) and d) are carried out in separate reaction steps, preferably in separate reactors or separate reaction zones.

[0121] 10. Process according to any of the preceding statements, wherein the temperature during step b) is at least 150°C, preferably at least 200°C, preferably at least 250°C, preferably at least 300°C, preferably at least 350°C, preferably at least 380°C.

[0122] 11. Process according to any of the preceding statements, wherein the temperature during step b) is at most 900°C, preferably at most 800°C, preferably at most 700°C, preferably at most 600°C, preferably at most 550°C, preferably at most 520°C.

[0123] 12. Process according to any of the preceding statements, wherein the temperature during step b) is at least 150°C to at most 900°C, preferably at least 200°C to at most 800°C, preferably at least 250°C to at most 700°C, preferably at least 300°C to at most 600°C, preferably at least 350°C to at most 550°C, preferably at least 380°C to at most 520°C.

[0124] 13. The process according to any of the preceding statements, wherein the pressure during step b) is at least 1.0 bar, preferably at least 1.5 bar, preferably at least 2.0 bar, preferably at least 2.5 bar, preferably at least 3.0 bar, preferably at least 5.0 bar, preferably at least 10.0 bar.

[0125] 14. The process according to any of the preceding statements, wherein the pressure during step b) is at most 50.0 bar, preferably at most 45.0 bar, preferably at most 40.0 bar, preferably at most 35.0 bar, preferably at most 30.0 bar, preferably at most 25.0 bar, preferably at most 20.0 bar.

[0126] 15. The process according to any of the preceding statements, wherein the pressure during step b) is at least 1.0 bar to at most 50.0 bar, preferably at least 1.5 bar to at most 45.0 bar, preferably at least 2.0 bar to at most 40.0 bar, preferably at least 2.5 bar to at most 35.0 bar, preferably at least 3.0 bar to at most 30.0 bar, preferably at least 5.0 bar to at most 25.0 bar, preferably at least 10.0 bar to at most 20.0 bar.

[0127] 16. A process according to any of the preceding statements, wherein in step b), the gaseous feed stream is contacted with the halogen reactant (X2) for at least 0.1 minutes to a maximum of 2.0 minutes, preferably at least 0.2 minutes to a maximum of 1.7 minutes, preferably at least 0.5 minutes to a maximum of 1.5 minutes, preferably at least 0.7 minutes to a maximum of 1.2 minutes.

[0128] 17. The process according to any of the preceding statements, wherein in step c), a hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising the hydrogen halide with an aqueous absorbent capable of absorbing the hydrogen halide (HX), and preferably an aqueous hydrogen halide (HX) solution, thereby forming an aqueous hydrogen halide (HX) stream.

[0129] 18. A process according to any one of the preceding statements, wherein polyhalogenated alkanes are formed during step b), preferably wherein the polyhalogenated alkanes formed during step b) comprise polyhalogenated methane and optionally polyhalogenated C 2+ Alkanes.

[0130] 19. A process according to any one of the preceding statements, wherein the polyhalogenated alkanes formed in step b) of the process comprise dihalomethanes (CH2X2).

[0131] 20. A process according to any one of the preceding statements, wherein the process comprises the step of separating the polyhalogenated alkanes formed in step b) from the effluent stream, thereby producing a polyhalogenated alkanes stream, and preferably the process comprises separating the polyhalogenated alkanes formed in step b) from the effluent stream before separating the hydrogen halide from the effluent stream.

[0132] 21. A process according to any one of the preceding statements, wherein the polyhalogenated alkanes formed in step b) of the process are separated from the effluent stream by distillation.

[0133] 22. A process according to any one of the preceding statements, wherein the polyhalogenated alkanes formed in step b) of the process are used as a polyhalogenated methane stream and a polyhalogenated C 2+ The alkane stream is separated from the effluent stream, preferably by distillation.

[0134] 23. A process according to any one of the preceding statements, wherein C 2+ The alkyl monohalide is formed in step b).

[0135] 24. The process according to any one of the preceding statements, wherein the process comprises separating the C formed in step b) of the process from the effluent stream. 2+ Alkyl monohalide step.

[0136] 25. A process according to any one of the preceding statements, wherein the process comprises separating the C formed in step b) from the effluent stream before separating the hydrogen halide from the effluent stream. 2+ Alkyl monohalides.

[0137] 26. The process according to any one of the preceding statements, wherein the process comprises separating the C2+ alkyl monohalide formed in step b) from the effluent stream after separating the polyhalogenated alkanes from the effluent stream.

[0138] 27. A process for producing dimethyl ether (DME) and hydrogen (H2) from methane, preferably a process for producing dimethyl ether (DME) and hydrogen (H2) from methane according to any of the preceding statements, comprising the following steps:

[0139] a) providing a gaseous feed stream comprising methane;

[0140] b) reacting the gaseous feed stream with at least one halogen reactant (X2) in an effective manner to produce a reaction mixture comprising methyl halide (MeX), and hydrogen halide (HX), polyhalogenated alkanes, C 2+ reacting an alkyl monohalide and optionally an effluent stream of unreacted methane under reaction conditions;

[0141] c) separating the following substreams from the effluent stream obtained in step b):

[0142] c1) polyhalogenated alkane stream;

[0143] c2)C 2+ an alkyl monohalide stream;

[0144] c3) a hydrogen halide (HX) stream; and

[0145] c4) a methyl halide (MeX) stream, which optionally comprises unreacted methane;

[0146] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0147] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2).

[0148] 28. A process according to statement 27, wherein the process further comprises the step of recovering a stream of methanol and optionally unreacted methane after step d).

[0149] 29. A process according to any one of the preceding statements, wherein the C formed in step b) of the process 2+ The alkyl monohalide is separated from the effluent stream by distillation.

[0150] 30. The process according to any one of the preceding statements, wherein the methyl halide (MeX) stream separated in step c) is a gaseous stream.

[0151] 31. The process according to any one of the preceding statements, wherein the methyl halide (MeX) stream separated in step c) is essentially free of polyhalogenated alkanes.

[0152] 32. A process according to any one of the preceding statements, wherein the methyl halide (MeX) stream separated in step c) is substantially free of C 2+ Alkyl monohalides.

[0153] 33. Process according to any of the preceding statements, wherein the hydrogen halide (HX) stream obtained in step c) is dry.

[0154] 34. The process according to any of the preceding statements, wherein step c) comprises separating from the effluent stream:

[0155] (i) a methyl halide (MeX) stream, optionally containing unreacted methane and optionally C 2+ Alkyl monohalides;

[0156] (ii) a hydrogen halide (HX) stream; and,

[0157] (iii) an optional polyhalogenated alkane stream, which may include a polyhalogenated methane stream and a polyhalogenated C 2+ Alkane flow.

[0158] 35. A process according to any one of the preceding statements, wherein the methyl halide (MeX) stream comprises unreacted methane.

[0159] 36. A process according to any one of the preceding statements, wherein the methyl halide (MeX) stream comprises C 2+ Alkyl monohalides.

[0160] 37. The process according to any of the preceding statements, wherein step c) comprises separating from the effluent stream:

[0161] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane;

[0162] (ii) a hydrogen halide (HX) stream; and,

[0163] (iii) a polyhalogenated alkane stream comprising a polyhalogenated methane stream and optionally a polyhalogenated C 2+ an alkane stream; and,

[0164] (iv) Optional C 2+ Alkyl monohalide stream.

[0165] 38. A process according to any of the preceding statements, wherein the gaseous feed stream comprises at least 75.0 volume % methane, preferably at least 80.0 volume % methane, preferably at least 85.0 volume % methane, preferably at least 90.0 volume % methane, preferably at least 95.0 volume % methane, preferably at least 98.0 volume % methane, preferably at least 99.0 volume % methane, preferably at least 99.9 volume % methane, based on the total volume of the gaseous feed stream.

[0166] 39. A process according to any of the preceding statements, wherein the gaseous feed stream comprises natural gas, biogas, refinery gas, or any mixture thereof.

[0167] 40. A process according to any of the preceding statements, wherein the gaseous feed stream used in step a) of the process is essentially free of sulfur species, for example it contains less than 1.0 mol%, or less than 0.5 mol%, or less than 0.1 mol%, or less than 0.01 mol%, or less than 0.001 mol%, or less than 0.0001 mol%, or less than 0.00001 mol% of sulfur species.

[0168] 41. A process according to any one of the preceding statements, wherein the solid metal oxide (MO) (s) ) is a metal hydroxide provided on a solid support, preferably wherein the support is a silica or alumina support.

[0169] 42. A process according to any of the preceding statements, wherein the metal oxide is selected from the list comprising or consisting of calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), copper oxide (CuO), and any mixture thereof.

[0170] 43. The process according to any of the preceding statements, wherein the metal oxide is calcium oxide (CaO), magnesium oxide (MgO), or a mixture thereof, preferably, the metal oxide is a mixture of calcium oxide (CaO) and magnesium oxide (MgO).

[0171] 44. A process according to any one of the preceding statements, wherein in step d) a methyl halide (MeX) is reacted with a solid metal oxide (MO (s) ) for at least 0.1 minutes to at most 100.0 minutes, preferably at least 0.2 minutes to at most 75.0 minutes, preferably at least 0.5 minutes to at most 60.0 minutes, preferably at least 1.0 minutes to at most 45.0 minutes, preferably at least 2.0 minutes to at most 30.0 minutes, preferably at least 3.0 minutes to at most 15.0 minutes, preferably at least 4.0 minutes to at most 10.0 minutes, preferably at least 4.0 minutes to at most 6.0 minutes.

[0172] 45. The process according to any of the preceding statements, wherein the temperature during step d) is at least 50°C, preferably at least 70°C, preferably at least 80°C, preferably at least 90°C, preferably at least 100°C, preferably at least 120°C.

[0173] 46. ​​The process according to any of the preceding statements, wherein the temperature during step d) is at most 500°C, preferably at most 450°C, preferably at most 400°C, preferably at most 350°C, preferably at most 300°C, preferably at most 250°C.

[0174] 47. The process according to any of the preceding statements, wherein the temperature during step d) is at least 50°C to at most 500°C, preferably at least 70°C to at most 450°C, preferably at least 80°C to at most 400°C, preferably at least 90°C to at most 350°C, preferably at least 100°C to at most 300°C, preferably at least 120°C to at most 250°C.

[0175] 48. The process according to any of the preceding statements, wherein the pressure during step d) is at least 1.0 bar, preferably at least 1.2 bar, preferably at least 1.5 bar, preferably at least 1.7 bar, preferably at least 2.0 bar, preferably at least 5.0 bar, preferably at least 10.0 bar.

[0176] 49. The process according to any of the preceding statements, wherein the pressure during step d) is at most 40.0 bar, preferably at most 35.0 bar, preferably at most 30.0 bar, preferably at most 25.0 bar, preferably at most 20.0 bar, preferably at most 15.0 bar, preferably at most 10.0 bar.

[0177] 50. The process according to any of the preceding statements, wherein the pressure during step d) is at least 1.0 bar to at most 40.0 bar, preferably at least 1.2 bar to at most 35.0 bar, preferably at least 1.5 bar to at most 30.0 bar, preferably at least 1.7 bar to at most 25.0 bar, preferably at least 2.0 bar to at most 20.0 bar, preferably at least 5.0 bar to at most 20.0 bar, preferably at least 10.0 bar to at most 15.0 bar.

[0178] 51. A process according to any one of the preceding statements, wherein polyhalogenated methanes are converted to methanol, preferably by hydrogenating the polyhalogenated methanes to form methyl halides, followed by reacting the methyl halides with a solid metal oxide (MOH (s) ) under reaction conditions effective to produce the corresponding alcohol.

[0179] 52. A process according to any of the preceding statements, wherein polyhalomethanes are converted to DME, preferably by hydrogenating the polyhalomethanes to form methyl halides and subsequently contacting the methyl halides with a solid metal oxide under reaction conditions effective to produce DME.

[0180] 53. The process according to any one of the preceding statements, wherein the process further comprises the following steps:

[0181] f) Regenerating the metal halide (MX) into a metal oxide (MO) and a halogen reactant (X2).

[0182] 54. The process according to any of the preceding statements, wherein the metal halide (MX) is regenerated in step f) by contacting the metal halide (MX) with steam and oxygen (O2) or air, thereby forming a metal hydroxide (MOH) and a halogen reactant (X2).

[0183] 55. The process according to any of the preceding statements, wherein the temperature during step f) is at least 150°C, preferably at least 200°C, preferably at least 250°C, preferably at least 300°C, preferably at least 350°C, preferably at least 400°C.

[0184] 56. Process according to any of the preceding statements, wherein the temperature during step f) is at most 1600°C, preferably at most 1400°C, preferably at most 1200°C, preferably at most 1000°C, preferably at most 800°C, preferably at most 600°C.

[0185] 57. The process according to any of the preceding statements, wherein the temperature during step f) is at least 150°C to at most 1600°C, preferably at least 200°C to at most 1400°C, preferably at least 250°C to at most 1200°C, preferably at least 300°C to at most 1000°C, preferably at least 350°C to at most 800°C, preferably at least 400°C to at most 600°C.

[0186] 58. The process according to any of the preceding statements, wherein the pressure during step f) is at least 0.5 bar, preferably at least 0.8 bar, preferably at least 0.9 bar, preferably at least 1.0 bar, preferably at least 1.1 bar, preferably at least 5.0 bar, preferably at least 10.0 bar.

[0187] 59. The process according to any of the preceding statements, wherein the pressure during step f) is at most 50.0 bar, preferably at most 45.0 bar, preferably at most 40.0 bar, preferably at most 35.0 bar, preferably at most 30.0 bar, preferably at most 25.0 bar, preferably at most 20.0 bar, preferably at most 15.0 bar.

[0188] 60. The process according to any of the preceding statements, wherein the pressure during step f) is at least 0.5 bar to at most 50.0 bar, preferably at least 0.8 bar to at most 45.0 bar, preferably at least 0.9 bar to at most 40.0 bar, preferably at least 1.0 bar to at most 35.0 bar, preferably at least 1.1 bar to at most 30.0 bar, preferably at least 5.0 bar to at most 25.0 bar, preferably at least 10.0 bar to at most 20.0 bar, preferably at least 10.0 bar to at most 15.0 bar.

[0189] 61. The process according to any one of the preceding statements, further comprising the step of returning the halogen reactant (X2) obtained in step e) and / or step f) to step b) of the process.

[0190] 62. The process according to any of the preceding statements, wherein the halogen reactant (X2) obtained in step e) and / or step f) is purified before being fed to step b), and preferably purified by condensation of the halogen reactant (X2).

[0191] 63. Process according to any of the preceding statements, wherein the halogen reactant (X2) obtained in step e) and / or step f) is dried, preferably over molecular sieves, before being fed to step b).

[0192] 64. A process according to any one of the preceding statements, wherein step e) of the process comprises supplying an aqueous solution of hydrogen halide (HX) to an electrolytic cell comprising a positive electrode and a negative electrode, and electrolytically decomposing the hydrogen halide by maintaining a potential between the electrodes of about 0.5 to 2.5 V.

[0193] 65. A process according to any one of the preceding statements, wherein step e) of the process comprises supplying an aqueous solution of hydrogen halide (HX) to an electrolytic cell comprising a positive electrode and a negative electrode and reacting the HX solution by maintaining a current between the electrodes of about 100 to 800 mA / cm 2 The hydrogen halide is electrolytically decomposed by a current density of 1000 nm.

[0194] 66. A process according to any of the preceding statements, wherein the electrolysis cell is a polymer electrolyte membrane cell (PEM) containing at least a proton conducting membrane.

[0195] 67. The process according to any of the preceding statements, wherein the hydrogen halide is decomposed in step e) at a temperature of 20 to 95°C.

[0196] 68. The process according to any of the preceding statements, wherein the hydrogen halide is decomposed in step e) at a pressure of 1 to 50 bar.

[0197] 69. A process according to any of the preceding statements, wherein the gaseous hydrogen (H2) stream produced in step e) comprises at least 90.0 mol%, e.g., at least 95.0 mol%, or at least 99.0 mol%, or at least 99.5 mol%, or at least 99.9 mol% hydrogen.

[0198] 70. A process for producing dimethyl ether (DME) and hydrogen (H2) from methane according to any one of the preceding statements, comprising the steps of:

[0199] a) providing a gaseous feed stream comprising methane,

[0200] b) reacting the gaseous feed stream with bromide (Br2) under reaction conditions effective to produce an effluent stream comprising methyl bromide (MeBr) and hydrogen bromide (HBr), and wherein the effluent stream optionally comprises unreacted methane and optionally polybrominated alkanes;

[0201] c) separating from the effluent stream obtained in b) the following:

[0202] (i) a methyl bromide (MeBr) stream, optionally comprising unreacted methane, and

[0203] (ii) a hydrogen bromide (HBr) stream;

[0204] (iii) optionally, a polybrominated alkane stream;

[0205] d) mixing the methyl bromide (MeBr) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce metal bromide (MBr) and dimethyl ether (DME); and,

[0206] e) decomposing the hydrogen bromide (HBr) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising bromine (Br2), and

[0207] f) optionally, regenerating the metal bromide (MBr) into a metal oxide (MO) and bromine (Br2), preferably by contacting the metal bromide (MBr) with oxygen (O2) or air, thereby forming the metal oxide (MO) and bromine (Br2), and

[0208] g) optionally, returning the bromine (Br2) obtained in step e) and / or step f) to step b) of the process, and

[0209] h) Optionally, after step d), a stream comprising dimethyl ether and optionally unreacted methane is recovered.

[0210] 71. A process according to any of the preceding statements, wherein the process further comprises the step of removing unreacted methane from the effluent stream, preferably distilling the unreacted methane.

[0211] 72. A process according to any one of the preceding statements, wherein the process further comprises the step of removing unreacted methane from the methyl halide (MeX) stream, preferably distilling the unreacted methane.

[0212] 73. The process according to any one of the preceding statements, wherein the process further comprises the step of removing unreacted methane from the dimethyl ether produced in step d), preferably distilling the unreacted methane.

[0213] 74. The process according to any of the preceding statements, wherein the removed unreacted methane is recycled or fed to step a) and / or step b) of the process.

[0214] 75. A process according to any of the preceding statements, wherein the process is a continuous process.

[0215] 76. A system for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising:

[0216] - a halogenation reactor (1) configured to react a gaseous feed stream comprising methane with at least one halogen reactant (X2) to form an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX) and optionally unreacted methane,

[0217] - a separation system (2) fluidly connected to the halogenation reactor (1) and configured to receive an effluent stream from the halogenation reactor (1) and configured to separate a hydrogen halide (HX) stream and a methyl halide (MeX) stream from the effluent stream;

[0218] - a dimethyl ether synthesis reactor (3) fluidically connected to the separation system (2) and configured to receive a methyl halide (MeX) stream from the separation system (2) and to combine the methyl halide (MeX) stream with a solid metal oxide (MO (s) ) to form a metal halide (MX) and dimethyl ether (DME); and

[0219] - an electrolysis unit (4) comprising at least one electrolysis cell and a power source for supplying electric current to the electrolysis cell, the electrolysis cell being fluidically connected to the separation system (2) and configured to receive a hydrogen halide (HX) stream and to decompose the hydrogen halide (HX) stream into a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2);

[0220] - a feed stream supply system (5) for supplying a gaseous feed stream comprising methane to the halogenation reactor (1);

[0221] - a halogen supply system (6) for supplying a halogen reactant (X2) to the halogenation reactor (1);

[0222] - an effluent collection system (10) configured to collect an effluent stream from the halogenation reactor (1) and to feed the collected effluent stream to the separation system (2);

[0223] - a dimethyl ether recovery system (7) configured to recover a stream containing dimethyl ether (DME) from the dimethyl ether synthesis reactor (3);

[0224] - a hydrogen recovery system (8) configured to recover a gaseous hydrogen (H2) stream from the electrolysis unit (4);

[0225] - a halogen recovery system (9) configured to recover the halogen reactant (X2) from the electrolysis unit (4);

[0226] - a hydrogen halide transfer system (12) configured to collect a hydrogen halide (HX) stream from the separation system (2) and supply the collected hydrogen halide (HX) stream to the electrolysis unit (4);

[0227] - a methyl halide transfer system (11) configured to collect a methyl halide (MeX) stream from the separation system (2) and supply the collected methyl halide (MeX) stream to a dimethyl ether synthesis reactor (3),

[0228] - Optionally, an absorbent supply line (12) for supplying an aqueous absorbent, preferably an aqueous hydrogen halide (HX) solution, to the separation system (2);

[0229] - optionally, a polyhalogenated alkane removal unit configured to receive the effluent stream from the halogenation reactor (1) and to remove polyhalogenated alkanes from the effluent stream, and,

[0230] - Optionally, C 2+ an alkyl monohalide removal unit configured to receive an effluent stream from the halogenation reactor (1) and remove C 2+ Alkyl monohalides.

[0231] In a first aspect, the present invention provides a process for producing dimethyl ether (DME) and hydrogen (H2) from methane. The process comprises, in particular, the following steps:

[0232] a) providing a gaseous feed stream comprising methane;

[0233] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX), and wherein the effluent stream optionally comprises unreacted methane;

[0234] c) separating from the effluent stream obtained in step b) the following:

[0235] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0236] (ii) hydrogen halide (HX) stream;

[0237] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0238] The hydrogen halide (HX) stream separated in step c) is decomposed by electrolysis under conditions effective to produce a stream of gaseous hydrogen (H2) and a stream comprising the halogen reactant (X2).

[0239] Specifically, the present invention provides a process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the following steps:

[0240] a) providing a gaseous feed stream comprising methane;

[0241] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX), and hydrogen halide (HX), optionally polyhalogenated alkane, and optionally unreacted methane;

[0242] c) separating from the effluent stream obtained in step b) the following:

[0243] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0244] (ii) an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream;

[0245] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0246] e) decomposing the aqueous hydrogen halide (HX) stream, or the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2);

[0247] wherein in step c) the hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising said hydrogen halide with an aqueous absorbent or by distillation, thereby forming an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream, respectively.

[0248] More specifically, a process for producing dimethyl ether (DME) and hydrogen (H2) from methane according to an embodiment of the present invention includes the following steps:

[0249] a) providing a gaseous feed stream comprising methane;

[0250] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX), hydrogen halide (HX), optionally polyhalogenated alkane, and optionally unreacted methane;

[0251] c) separating from the effluent stream obtained in step b) the following:

[0252] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and,

[0253] (ii) hydrogen halide (HX) stream;

[0254] (iii) optionally, a polyhalogenated alkane stream;

[0255] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and,

[0256] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2),

[0257] f) regenerating the metal halide (MX) into a metal oxide (MO) and a halogen reactant (X2), preferably by contacting the metal halide (MX) with oxygen (O2) or air, thereby forming a metal oxide (MO) and a halogen reactant (X2); and

[0258] g) Optionally, returning the halogen reactant (X2) obtained in step e) and / or step f) to step b) of the process.

[0259] According to the present invention, steps b) and d) are preferably carried out in separate reaction steps, preferably in separate reactors or separate reaction zones.The process of the present invention is preferably a continuous process.

[0260] The present invention provides a process for producing a stream of dimethyl ether and hydrogen starting from a gaseous feed stream comprising or consisting essentially of methane (e.g. biogas or natural gas). In other words, the present invention provides a process for producing dimethyl ether from a gaseous stream comprising methane (not synthesis gas).

[0261] The present process comprises reacting a gaseous feed stream with at least one halogen reactant to form a methyl halide and a hydrogen halide, followed by reacting the produced methyl halide in the presence of a solid metal oxide to form a metal halide and dimethyl ether. The present process is further characterized in that it comprises the steps of separating the methyl halide produced by reacting the gaseous feed stream with the halogen reactant from other halogen-containing compounds (and in particular from the hydrogen halide produced in this step), and then subjecting the produced methyl halide to an ether synthesis reaction in the presence of the solid metal oxide. Such a separation step upstream of the ether synthesis step advantageously and unexpectedly allows for efficient conversion of the methyl halide stream into a dimethyl ether stream with minimal or no production of undesirable by-products, such as, for example, methanol (MeOH).

[0262] In addition, the present process also provides the following steps: wherein the separated hydrogen halide can be electrolytically treated to decompose into separate streams of hydrogen and halogen reactant, thereby producing a valuable by-product, i.e. hydrogen. In addition, the collected halogen reactant can be advantageously reused in the present process.

[0263] The present process thus provides an efficient process for converting methane to dimethyl ether, wherein hydrogen is produced as an industrially relevant by-product.

[0264] The first step of the process involves providing a gaseous feed stream comprising methane.

[0265] The terms "gaseous feed stream" and "reactant gas" are used synonymously herein and refer to a gaseous stream comprising methane.

[0266] In some embodiments of the process according to the invention, the gaseous feed stream used may also comprise C 2+ Alkanes.

[0267] The term "alkane" refers to an organic compound that is either a non-cyclic saturated hydrocarbon or a cyclic saturated hydrocarbon. As used herein, an alkane may be linear, branched, or cyclic (but not aromatic). Preferably, the alkane is linear or branched. In a preferred embodiment, the alkane is a non-cyclic saturated hydrocarbon and satisfies the following formula C i H(2i+2) , where i is an integer. Examples are methane, ethane, propane, butane, pentane and hexane.

[0268] As used herein, the term "C 2+ "Alkanes" are intended to mean alkanes having greater than two carbon atoms. In some embodiments, C 2+ Alkanes are C 2-6 Alkanes, i.e. alkanes containing two to six carbon atoms, thus for example C2, C3, C4, C5, C6 alkanes, and any mixtures thereof. When a subscript is used after a carbon atom herein, the subscript refers to the number of carbon atoms that the named group may contain. 2+ Examples of alkanes are ethane, propane, butane, pentane, hexane, and mixtures of two or more of these.

[0269] For example, in some embodiments, the gaseous feed stream employed may comprise a mixture of methane and ethane, or a mixture of methane and propane, or a mixture of methane, ethane, and propane.

[0270] Preferably, the gaseous feed stream comprising methane used in the present process comprises at least 75.0% by volume of methane, preferably at least 80.0% by volume of methane, preferably at least 85.0% by volume of methane, preferably at least 90.0% by volume of methane, preferably at least 95.0% by volume of methane, preferably at least 98.0% by volume of methane, preferably at least 99.0% by volume of methane, preferably at least 99.9% by volume of methane, based on the total volume of the gaseous feed stream.

[0271] Optionally, the gaseous feed stream applied in the process according to the invention may also contain hydrogen. Preferably, the molar ratio of this optional hydrogen to methane in the gaseous feed stream may be in the range of about 1:4 to 0:1.

[0272] Optionally, the gaseous feed stream used in the process according to the present invention may also contain small amounts of other components selected from oxygen, nitrogen or carbon dioxide. Preferably, such other components may be present in an amount of less than 2.0 mol%, such as less than 1.5 mol%, or less than 1.0 mol%, or less than 0.5 mol%, based on the total gaseous feed stream. In some embodiments, the composition of the gaseous feed stream is comparable to that of natural gas or biogas, or a mixture thereof.

[0273] In some embodiments, the gaseous feed stream used in step a) of the process comprises natural gas, biogas, refinery gas (i.e., a gaseous fraction from a crude oil refinery), or any mixture thereof. Preferably, the gaseous feed stream comprises natural gas and / or biogas.

[0274] In some embodiments of the process according to the present invention, the gaseous feed stream gas used in step a) of the process is natural gas. The term "natural gas" refers to a multi-component gas obtained from a crude oil well (associated gas) or from an underground gas-bearing formation (non-associated gas). The composition and pressure of natural gas can vary significantly. A typical natural gas stream contains methane as a significant component. Natural gas may also contain ethane, higher molecular weight hydrocarbons (e.g., C2+ alkanes), acid gases (e.g., carbon dioxide, hydrogen sulfide, carbonyl sulfide, carbon disulfide, and mercaptans), and small amounts of contaminants such as water, nitrogen, iron sulfide, wax, and crude oil. As used herein, "natural gas" may also include gas obtained from the regasification of liquefied natural gas, which has been purified to remove contaminants (e.g., water, acid gases) and most of the higher molecular weight hydrocarbons (e.g., C2+ alkanes). 12+ Conventional methods may be used to remove impurities and / or adjust the relative amounts of hydrocarbon compounds present in the gaseous feed stream.

[0275] In some embodiments of the process according to the present invention, the gaseous feed stream used in step a) of the process is biogas or biomethane produced from biogas. The term "biogas" refers to a multi-component gas consisting primarily of methane and carbon dioxide, produced by anaerobic digestion or by methanogenesis from feedstocks such as, but not limited to, agricultural waste, manure, municipal waste, plant material, sewage, green waste, or food waste. Biogas can be purified to remove carbon dioxide, oxygen, sulfur, and / or silicon-containing compounds to produce biomethane, which can be used as the gaseous feed stream in the process.

[0276] In some embodiments, the natural gas may be of fossil origin. In some embodiments, the natural gas may be of renewable origin. Natural gas of renewable origin includes, for example, gas produced from existing waste streams and various renewable and sustainable biomass sources (including but not limited to animal waste, crop residues and food waste, organic waste from cattle farms and farms), as well as gas produced from the biological decomposition of naturally occurring organic waste in facilities such as wastewater treatment plants and landfills. In some embodiments, the natural gas may comprise a combination of natural gas from fossil sources and natural gas from renewable sources.

[0277] Preferably, the gaseous feed stream used in step a) of the process is substantially free of sulfur species, for example, it contains less than 1.0 mol%, or less than 0.5 mol%, or less than 0.1 mol%, or less than 0.01 mol%, or less than 0.001 mol%, or less than 0.0001 mol%, or less than 0.00001 mol% of sulfur species. In an embodiment, the gaseous feed stream is free of sulfur species. For example, sulfur species may be species in the form of H2S, COS, CS2. If desired, desulfurization can be achieved by adsorption and / or absorption.

[0278] In some other embodiments of the process according to the present invention, the gaseous feed stream consists of methane.

[0279] Step b) of the process of the present invention comprises reacting a gaseous feed stream as defined herein with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX). The effluent stream may optionally contain unreacted methane.

[0280] The halogen reactant used in this step of the process can be selected from bromine (Br ), chlorine (Cl ), fluorine (F ) and iodine (I ), and is preferably bromine. In particular, the collection of bromine in processes e) and f) requires less energy, reactants and / or equipment.

[0281] Therefore, in a preferred embodiment, the present invention provides a process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the steps of:

[0282] a) providing a gaseous feed stream comprising methane;

[0283] b) reacting the gaseous feed stream with bromine (Br2) under reaction conditions effective to produce an effluent stream comprising methyl bromide (MeBr), hydrogen bromide (HBr), and wherein the effluent stream optionally comprises unreacted methane;

[0284] c) separating hydrogen bromide (HBr) from the effluent stream to recover a methyl bromide (MeBr) stream;

[0285] d) mixing the methyl bromide (MeBr) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce metal bromide (MBr) and dimethyl ether (DME);

[0286] e) decomposing the hydrogen bromide (HBr) separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising bromine (Br2);

[0287] f) optionally, regenerating the metal bromide (MBr) into a metal oxide (MO) and bromine (Br2); and,

[0288] g) Optionally, returning the bromine (Br2) obtained in step e) and / or step f) to step b) of the process.

[0289] Preferably, the halogen reactant, such as bromine, is introduced directly into the reaction zone. The halogen reactant can be introduced into the reaction zone in a liquid state. The halogen reactant can be introduced into the reaction zone in pure form or dissolved in an aqueous hydrogen halide solution.

[0290] According to the present process, step b) of the process is preferably carried out at a temperature during step b) of at least 150° C., preferably at least 200° C., preferably at least 250° C., preferably at least 300° C., preferably at least 350° C., preferably at least 380° C. According to the present process, step b) of the process is preferably carried out at a temperature during step b) of at most 900° C., preferably at most 800° C., preferably at most 700° C., preferably at most 600° C., preferably at most 550° C., preferably at most 520° C.

[0291] For example, in the present process, preferred temperature conditions for the reaction between the feed stream comprising methane and the halogen reactant are comprised between 150° C. and 900° C., preferably comprised between 200° C. and 800° C., preferably comprised between 250° C. and 700° C., preferably comprised between 300° C. and 600° C., preferably comprised between 350° C. and 550° C., preferably comprised between 380° C. and 520° C. In some embodiments, the exothermic nature of the reaction is sufficient to maintain the temperature during the reaction.

[0292] According to the present process, step b) of the process is carried out at a reaction pressure of at least 1.0 bar, preferably at least 1.5 bar, preferably at least 2.0 bar, preferably at least 2.5 bar, preferably at least 3.0 bar, preferably at least 5.0 bar, preferably at least 10.0 bar. According to the present process, step b) of the process is carried out at a reaction pressure of at most 50.0 bar, preferably at most 45.0 bar, preferably at most 40.0 bar, preferably at most 35.0 bar, preferably at most 30.0 bar, preferably at most 25.0 bar, preferably at most 20.0 bar.

[0293] For example, preferred pressure conditions for the reaction between the feed stream comprising methane and the halogen reactant in the present process include between 1.0 bar and 50.0 bar, preferably between 1.5 bar and 45.0 bar, preferably between 2.0 bar and 40.0 bar, preferably between 2.5 bar and 35.0 bar, preferably between 3.0 bar and 30.0 bar, preferably between 5.0 bar and 25.0 bar, and preferably between 10.0 bar and 20.0 bar.

[0294] In some embodiments of the present process, the feed stream comprising methane and the halogen reactant are used in a methane / halogen molar ratio comprised between 2 / 1 and 7 / 1, preferably between 3 / 1 and 6 / 1, preferably between 4 / 1 and 5 / 1.

[0295] The time required for the gaseous feed stream to react with the halogen will vary depending on the specific feed material used, the halogen used, and the reaction temperature. In an example, the gaseous feed stream is contacted with the halogen reactant (X2) in step b) at a temperature between 380°C and 520°C, at a pressure between 10 bar and 20 bar, and for at least 0.1 minute to a maximum of 2.0 minutes.

[0296] The effluent stream obtained from the reaction step b) mainly comprises methyl halide and hydrogen halide. The effluent stream may also contain a certain amount of unreacted methane. At the same time, depending on the composition of the initial gaseous feed stream used in the process, the effluent stream may contain a certain amount of C 2+ Alkyl monohalides and / or a certain amount of polyhalogenated alkanes, such as polyhalogenated methane and / or polyhalogenated C 2+ Alkanes, which have been formed during reaction step b).

[0297] In a next step, the process of the present invention comprises separating the following from the effluent stream obtained in step b): a methyl halide (MeX) stream and a hydrogen halide (HX) stream. The methyl halide stream is then further reacted with a solid metal oxide (in step d) of the process), while the hydrogen halide stream is electrolyzed (in step e) of the process).

[0298] In a preferred embodiment, in step c) of the process, the hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising the hydrogen halide with an aqueous absorbent capable of absorbing the hydrogen halide (HX). For example, the hydrogen halide (HX) stream can be separated from the effluent stream in a separation system (e.g., in a quench column), preferably by contacting the gaseous effluent stream with a suitable aqueous absorbent, preferably in countercurrent contact.

[0299] Preferably, the aqueous absorbent used in step c) of the process is an aqueous hydrogen halide (HX) solution.

[0300] In some preferred embodiments of the present invention, the aqueous absorbent used in the process is an aqueous hydrogen halide (HX) solution, wherein the halogen anion used in the solution, such as a bromide anion, is the same halogen as the halogen reactant used in step b) of the process, such as bromine. Therefore, in some preferred embodiments, the halogen reactant used in step a) is bromide (Br2), and the hydrogen halide solution used in step c) is a hydrogen bromide (HBr) solution.

[0301] Preferably, the hydrogen halide solution as applied during separation step c) contains a weight fraction of hydrogen halide (HX) of at least 10.0 wt.-% to at most 40.0 wt.-%, for example at least 15.0 wt.-% to at most 35.0 wt.-%, or at least 20.0 wt.-% to at most 30.0 wt.-%, or at least 25.0 wt.-% to at most 30.0 wt.-%, wherein the wt.-% are expressed based on the total hydrogen halide solution.

[0302] In some embodiments of the process of the present invention, the effluent stream may comprise additional components in addition to methyl halide, hydrogen halide and optionally unreacted methane, depending on the composition of the initial gaseous feed stream used in the process.

[0303] In some embodiments of the process of the present invention, polyhalogenated alkanes are formed in step b) and are present in the effluent stream obtained after step b).

[0304] As used herein, the term "polyhalogenated alkane" is an alkane in which more than one hydrogen atom is replaced by a halogen atom (X), wherein X is preferably selected from Br, Cl, F, I and At, more preferably X is Br. As used herein, "polyhalogenated alkane" preferably refers to a polyhalogenated alkane such as a polyhalogenated C1-C6 alkane, preferably a polyhalogenated C1-C4 alkane, preferably a polyhalogenated C1-C3 alkane. When a subscript is used after a carbon atom herein, the subscript refers to the number of carbon atoms that the named group may contain.

[0305] In some embodiments, the term "polyhalogenated alkane" refers to a compound having the following formula (I):

[0306]

[0307] in:

[0308] -n is an integer, and n≥1, preferably 1≤n≥6; preferably 1≤n≥4; preferably 1≤n≥3;

[0309] - m is an integer, and m≥2; preferably 2≤m≥4, preferably 2≤m≥3; and,

[0310] -X is selected from Br, Cl, F, I and At, preferably X is Br.

[0311] In some embodiments, the polyhalogenated alkane comprises a polyhalogenated C1 alkane.

[0312] In some embodiments, the polyhalogenated alkane comprises a polyhalogenated C 2+ Alkanes.

[0313] In some embodiments, the polyhalogenated alkane comprises a polyhalogenated C1 alkane and a polyhalogenated C 2+ Alkanes.

[0314] The terms "polyhalogenated C1 alkane" and "polyhalogenated methane" are used interchangeably herein and are intended to mean a C1 alkane in which more than one hydrogen atom is replaced by a halogen atom (X), wherein X is preferably selected from Br, Cl, F, I and At, more preferably wherein X is Br.

[0315] In some embodiments, the terms "polyhalogenated C1 alkane" and "polyhalogenated methane" refer to compounds having the following formula (II):

[0316]

[0317] in:

[0318] - p is an integer, and p≥2; preferably 2≤p≥4, preferably 2≤p≥3; and,

[0319] -X is selected from Br, Cl, F, I and At, and preferably X is Br.

[0320] In some preferred embodiments, the "polyhalogenated methane" is selected from CH2X2, CHX2 and CX4, and any mixture thereof, wherein X is as defined above. For example, the polyhalogenated methane formed in step b) of the process includes dihalogenated methane (CH2X2). Preferred examples of polyhalogenated methanes include, but are not limited to, CH2Br2, CHBr3 and CBr4.

[0321] As used herein, the term "polyhalogenated C 2+ "Alkanes" refer to the following C 2+ Alkanes: wherein more than one hydrogen atom is replaced by a halogen atom (X), wherein X is preferably selected from Br, Cl, F, I and At, more preferably X is Br. Preferably, the polyhalogenated C 2+ Alkanes preferably refer to polyhalogenated C 2+ Alkanes such as polyhalogenated C2-C6 alkanes, preferably polyhalogenated C2-C4 alkanes, preferably polyhalogenated C2-C3 alkanes.

[0322] In some embodiments, the polyhalogenated C 2+ "Alkanes" refer to compounds having the following formula (III):

[0323]

[0324] in:

[0325] -q is an integer and q≥2, preferably 2≤q≥6; preferably 2≤q≥4; preferably 2≤q≥3;

[0326] - r is an integer and r≥2; preferably 2≤r≥4, preferably 2≤r≥3; and,

[0327] -X is selected from Br, Cl, F, I and At, preferably X is Br.

[0328] For example, the polyhalogenated C 2+ The alkanes may include polyhalogenated C2 alkanes (eg, dibromoethane) and / or polyhalogenated C3 alkanes (eg, dibromopropane).

[0329] In some embodiments of the process of the present invention, C 2+ Alkyl monohalides are also formed in step b) and are present in the effluent stream obtained after step b).

[0330] The term "C 2+ Alkyl monohalide" and "monohalogenated C 2+ "Alkanes" are used interchangeably herein and refer to the following C 2+ Alkanes: wherein a single hydrogen atom is replaced by a halogen atom (X), wherein X is preferably selected from Br, Cl, F, I and At, more preferably wherein X is Br. Preferably, the monohalogenated C 2+ Alkanes preferably refer to monohalogenated C 2+ For example, monohalogenated C2-C6 alkane, preferably monohalogenated C2-C4 alkane, preferably monohalogenated C2-C3 alkane.

[0331] In other words, the term "C 2+ Alkyl monohalide" and "monohalogenated C 2+ "Alkanes" refer to compounds having the following formula (IV):

[0332]

[0333] in:

[0334] -s is an integer, and s≥2; preferably 2≤s≥6; preferably 2≤s≥4; preferably 2≤s≥3, and,

[0335] -X is selected from Br, Cl, F, I and At, preferably X is Br.

[0336] For example, the C formed in step b) of the process 2+The alkyl monohalide may include a C2 alkyl monohalide (eg, ethyl bromide) and / or a C3 alkyl monohalide (eg, n-propyl bromide).

[0337] In view of this, the present process may include separating the polyhalogenated alkanes and / or C 2+ Thus, in some embodiments, step c) in the process of the present invention comprises separating from the effluent stream obtained in step b) the following:

[0338] - a methyl halide (MeX) stream; which optionally contains unreacted methane and / or optionally C 2+ Alkyl monohalides;

[0339] - a hydrogen halide (HX) stream; and

[0340] - Polyhalogenated alkane streams.

[0341] In some embodiments, C 2+ The alkyl monohalide is separated from the effluent stream in a separate stream, namely at C 2+ in the alkyl monohalide stream.

[0342] In some embodiments, it is preferred to separate the polyhalogenated alkane stream from the effluent stream by distillation, as follows:

[0343] - a stream which can be further separated, preferably by distillation, into a polyhalogenated methane stream and a polyhalogenated C 2+ an alkane stream; or

[0344] -Polyhalogenated methane streams and polyhalogenated C 2+ Alkane flow.

[0345] In some embodiments, step c) comprises a single separation step of the effluent stream, i.e., the effluent stream is separated in one step. In some embodiments, step c) comprises two separation steps, i.e., a hydrogen halide (HX) separation step and a polyhalogenated alkane separation step. In some embodiments, step c) comprises three separation steps, i.e., a hydrogen halide (HX) separation step, a polyhalogenated alkane separation step, and a C 2+ Alkyl monohalide separation step.

[0346] In one example, step c) in the process of the present invention comprises separating from the effluent stream obtained in step b) the following:

[0347] - a methyl halide (MeX) stream; which optionally contains unreacted methane and / or optionally contains C 2+ Alkyl monohalides;

[0348] - a hydrogen halide (HX) stream; and,

[0349] - Polyhalogenated alkane streams.

[0350] In a further example, step c) in the process of the present invention comprises separating from the effluent stream obtained in step b) the following:

[0351] - a methyl halide (MeX) stream; which optionally contains unreacted methane and / or optionally contains C 2+ Alkyl monohalides;

[0352] - a hydrogen halide (HX) stream; and,

[0353] - a polyhalogenated methane stream; and,

[0354] -Polyhalogenated C 2+ Alkane flow.

[0355] In a further example, step c) in the process of the present invention comprises separating from the effluent stream obtained in step b) the following:

[0356] - a methyl halide (MeX) stream; which optionally comprises unreacted methane;

[0357] - a hydrogen halide (HX) stream; and,

[0358] -C 2+ Alkyl monohalide stream.

[0359] In a further example, step c) in the process of the present invention comprises separating from the effluent stream obtained in step b) the following:

[0360] - a methyl halide (MeX) stream; which optionally comprises unreacted methane;

[0361] - Hydrogen halide (HX) logistics;

[0362] - a polyhalogenated alkane stream; and,

[0363] -C 2+ Alkyl monohalide stream.

[0364] In a further example, step c) in the process of the present invention comprises separating from the effluent stream obtained in step b) the following:

[0365] - a methyl halide (MeX) stream; which optionally comprises unreacted methane;

[0366] - Hydrogen halide (HX) logistics;

[0367] - Polyhalogenated methane streams;

[0368] -Polyhalogenated C 2+an alkane stream; and,

[0369] -C 2+ Alkyl monohalide stream.

[0370] Separation of polyhalogenated alkanes from the effluent stream has the following advantages: it allows recovery of a purified methyl halide (MeX) stream that contains less or no other polyhalogenated alkanes, such as polyhalogenated methanes and / or polyhalogenated C 2+ Alkanes, and thus such a purified methyl halide (MeX) stream can be advantageously converted into a stream of methanol without producing significant amounts of non-alcohol products other than alkanes. In this way, methanol can be produced with less than 10.000 ppm, preferably less than 7.000 ppm, preferably less than 5.000 ppm, preferably less than 3.000 ppm, preferably less than 2.000 ppm, preferably less than 1.000 ppm of non-alcohol products other than alkanes.

[0371] In particular, a preferred process for producing methanol (MeOH) and hydrogen (H2) from methane according to the present invention comprises the following steps:

[0372] a) providing a mixture comprising methane and optionally C 2+ a gaseous feed stream of an alkane;

[0373] b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX), hydrogen halide (HX), and wherein the effluent stream optionally comprises unreacted methane; C 2+ Alkyl monohalides and / or polyhalogenated alkanes, such as polyhalogenated methanes and / or polyhalogenated C 2+ Alkanes;

[0374] c) separating from the effluent stream obtained in step b) the following:

[0375] (i) a methyl halide (MeX) stream, optionally comprising unreacted methane;

[0376] (ii) hydrogen halide (HX) stream;

[0377] (iii) an optional polyhalogenated alkane stream, which may include a polyhalogenated methane stream and / or a polyhalogenated C 2+ an alkane stream; and,

[0378] (iv) Optional C 2+ Alkyl monohalide stream.

[0379] d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s)) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME);

[0380] e) decomposing the hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2);

[0381] f) optionally, regenerating the metal halide (MX) into a metal oxide (MO) and a halogen reactant (X2);

[0382] g) optionally, returning the halogen reactant (X2) obtained in step e) and / or step f) to step b) of the process; and

[0383] h) optionally, the polyhalogenated alkane stream and / or C2 + The alkyl monohalide stream is converted to its corresponding alcohol.

[0384] Preferably, the polyhalogenated alkanes formed in step b) of the process are separated from the effluent stream by distillation. For example, the polyhalogenated alkane stream or the polyhalogenated methane stream and the polyhalogenated C 2+ The alkane stream is separated from the effluent stream. Preferably, distillation is the preferred separation technique due to the large difference in molecular weight and therefore boiling point between polyhalogenated alkanes and monohalogenated compounds. Preferably, the polyhalogenated alkanes are separated from the effluent stream, and then the monohalogenated compounds (i.e., methyl halides, hydrogen halides, and C 2+ alkyl monohalide) is separated from the effluent stream.

[0385] In some preferred embodiments of the present invention, the process comprises the step of separating the polyhalogenated alkanes formed in step b) from the effluent stream to produce a polyhalogenated alkanes stream, whereby the polyhalogenated alkanes formed in step b) are separated from the effluent stream before separating the hydrogen halide from the effluent stream.

[0386] Preferably, the C formed in step b) of the process is distilled 2+ The alkyl monohalide is separated from the effluent stream. For example, the C 2+ An alkyl monohalide stream is separated from the effluent.

[0387] In some preferred embodiments of the present invention, the process comprises the following steps: 2+ Alkyl monohalide is separated from the effluent stream to produce C 2+ alkyl monohalide stream, thereby separating the hydrogen halide from the effluent stream Before, the C formed in step b) 2+ The alkyl monohalide is separated from the effluent stream, preferably by distillation.

[0388] In some embodiments, the process comprises combining a polyhalogenated methane stream with a polyhalogenated C 2+ The alkane stream is separated in a separate step and / or in a separate separation column. Alternatively, the process may comprise separating the polyhalogenated methane stream and the polyhalogenated C 2+ The alkane stream is separated in a single step and / or in a single separation column.

[0389] In some embodiments, the process includes separating the polyhalogenated alkane stream and the methyl halide stream in separate steps and / or in separate separation towers. Alternatively, the process may include separating the polyhalogenated alkane stream and the methyl halide stream in a single step and / or in a single separation tower.

[0390] The methyl halide (MeX) stream separated in step c) is preferably a gaseous stream.

[0391] In step c) hydrogen halide (HX) and optionally a polyhalogenated alkane stream and / or C 2+ After the alkyl monohalide stream is separated, the present process allows for the recovery of a stream comprising primarily methyl halide (MeX). Preferably, the separated methyl halide stream comprises at least 75.0 mol%, such as at least 80.0 mol%, or at least 85.0 mol%, or at least 90.0 mol% methyl halide, based on the total amount of the stream. However, it should be noted that the separated methyl halide stream may still contain a certain amount of unreacted methane.

[0392] Preferably, the methyl halide (MeX) stream separated in step c) is substantially free of hydrogen halide. In this context, the term "substantially free of hydrogen halide" is intended to mean that the amount of hydrogen halide in the stream is less than 10.00 mol%, such as less than 8.00 mol%, or less than 5.00 mol%, or less than 3.00 mol%, or less than 1.00 mol%, or less than 0.10 mol%, preferably less than 0.05 mol%, preferably less than 0.01 mol%, based on the total amount of the stream.

[0393] According to the present invention, the methyl halide (MeX) stream separated in step c) is also preferably "substantially free" of polyhalogenated alkanes. "Substantially free of polyhalogenated alkanes" in this context means that the methyl halide (MeX) stream obtained in step c) contains less than 1.0 mol %, such as less than 0.1 mol %, preferably less than 0.5 mol % of polyhalogenated alkanes, as defined herein.

[0394] According to the present invention, the methyl halide (MeX) stream separated in step c) is also preferably "substantially free" of polyhalogenated methanes. "Substantially free of polyhalogenated methanes" in this context means that the methyl halide (MeX) stream obtained in step c) contains less than 1.0 mol %, such as less than 0.1 mol %, preferably less than 0.5 mol % of polyhalogenated methanes, as defined herein.

[0395] According to the present invention, the methyl halide (MeX) stream separated in step c) is also preferably "substantially free" of polyhalogenated C 2+ Preferably, in this context, "substantially free of polyhalogenated C 2+ By "alkanes" is meant that the methyl halide (MeX) stream obtained in step c) contains less than 1.0 mol %, such as less than 0.1 mol %, preferably less than 0.5 mol % of polyhalogenated C 2+ Alkanes, as defined herein.

[0396] According to the present invention, the methyl halide (MeX) stream separated in step c) is also preferably "essentially free" of C 2+ Preferably, "substantially free of C 2+ "Alkyl monohalide" means that the methyl halide (MeX) stream obtained in step c) contains less than 1.0 mol %, such as less than 0.1 mol %, preferably less than 0.5 mol % of C 2+ Alkyl monohalide, as defined herein.

[0397] In the next step, the methyl halide (MeX) stream separated in step c) of the process is mixed with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME).

[0398] Examples of suitable metal oxides for use in the present process include, but are not limited to, metal oxides selected from the list comprising or consisting of calcium oxide (CaO), magnesium oxide (MgO), barium oxide (BaO), copper oxide (CuO), and any mixtures thereof.

[0399] Preferred examples of the solid metal oxide may be calcium oxide (CaO), magnesium oxide (MgO), or a mixture thereof. Preferably, the metal oxide is a mixture of calcium oxide (CaO) and magnesium oxide (MgO).

[0400] As used herein, the term "solid" refers to a metal oxide provided on a solid support, such as a silica or alumina support, more preferably a silica support. Preferably, the solid support is impregnated with the metal oxide. Preferably, the solid support is impregnated with a solution of the metal oxide and the impregnated solid support is then dried.

[0401] Step d) of the process of the present invention is preferably carried out at a temperature of at least 50°C, preferably at least 70°C, preferably at least 80°C, preferably at least 90°C, preferably at least 100°C, preferably at least 150°C. Step d) of the process of the present invention is preferably carried out at a temperature of at most 500°C, preferably at most 450°C, preferably at most 400°C, preferably at most 350°C, preferably at most 300°C, preferably at most 250°C. For example, preferred temperature conditions for reaction step d) include between 50°C and 500°C, preferably between 70°C and 450°C, preferably between 80°C and 400°C, preferably between 90°C and 350°C, preferably between 100°C and 300°C, preferably between 120°C and 250°C. In some embodiments, the temperature in step d) can be achieved by heat integration, for example, by utilizing heat harvested during the exothermic reaction in step b).

[0402] Step d) of the process of the present invention is preferably carried out at a reaction pressure of at least 1.0 bar, preferably at least 1.2 bar, preferably at least 1.5 bar, preferably at least 1.7 bar, preferably at least 2.0 bar, preferably at least 5.0 bar, preferably at least 10.0 bar. Step d) of the process of the present invention is preferably carried out at a reaction pressure of at most 40.0 bar, preferably at most 35.0 bar, preferably at most 30.0 bar, preferably at most 25.0 bar, preferably at most 20.0 bar, preferably at most 15.0 bar, preferably at most 10.0 bar. For example, preferred pressure conditions for reaction step d) include between 1.0 bar and 40.0 bar, preferably between 1.2 bar and 35.0 bar, preferably between 1.5 bar and 30.0 bar, preferably between 1.7 bar and 25.0 bar, preferably between 2.0 bar and 20.0 bar, preferably between 5.0 bar and 20.0 bar, preferably between 10.0 bar and 15.0 bar.

[0403] Preferably, the process of the present invention comprises reacting in step d) a methyl halide (MeX) with a solid metal oxide (MO (s) ) is reacted for at least 0.1 minutes to at most 100.0 minutes, preferably at least 0.2 minutes to at most 75.0 minutes, preferably at least 0.5 minutes to at most 60.0 minutes, preferably at least 1.0 minutes to at most 45.0 minutes, preferably at least 2.0 minutes to at most 30.0 minutes, preferably at least 3.0 minutes to at most 15.0 minutes, preferably at least 4.0 minutes to at most 10.0 minutes, preferably at least 4.0 minutes to at most 6.0 minutes.

[0404] In an example, the methyl halide is contacted with the solid metal oxide in step d) at a temperature between 120 and 250° C., at a pressure between 10 and 15 bar, and for at least 4 minutes and at most 6.0 minutes.

[0405] According to the present invention, it is preferred that step d) of the process is carried out in the absence of water.

[0406] The reaction product from reaction step d) comprises predominantly dimethyl ether (dimethyl ether stream) and metal halide (MX). In the reaction output, there are optionally also residual amounts of unreacted methane.

[0407] After step d), a stream comprising dimethyl ether may be recovered. Preferably, such a recovered dimethyl ether stream comprises, based on the total amount of the stream, at least 75.0 mol%, e.g., at least 80.0 mol%, or at least 85.0 mol%, or at least 95.0 mol% of dimethyl ether. However, it will be noted that the recovered methyl halide stream may still contain a certain amount of unreacted methane.

[0408] By separating the hydrogen halide from the effluent stream obtained after step b) of the process of the present invention, the present process allows the "purified" methyl halide stream to be subjected to the ether synthesis reaction in the presence of a solid metal oxide in step d). Thus, the separation step applied in step c) allows the reaction of the hydrogen halide on the solid metal oxide in step d) to be avoided. In this way, the present process avoids the conversion of hydrogen halide (HX) into metal halide (MX) and water during step d) of the process. Instead, the hydrogen halide (HX) present in the effluent stream after reaction step b) is further decomposed (in step e) into:

[0409] - a substantially pure hydrogen gas stream which makes more economic sense than water; and

[0410] - a halogen reactant, which can advantageously be reused in step b) of the process.

[0411] By separating the hydrogen halide from the effluent stream in step c), the production of "wet dimethyl ether" in step d) is also prevented; thus, the need for further drying of the dimethyl ether obtained in the process is avoided. Moreover, in the absence of hydrogen halide in the methyl halide stream supplied in step d), the solid metal oxide used in step d) of the process is still optimally suited for converting the methyl halide to dimethyl ether and does not undergo side reactions with such hydrogen halide. Furthermore, by preventing the formation of metal halide (MX) due to interaction with hydrogen halide, the need / frequency of regenerating the metal halide formed in step d) into solid metal oxide (which is necessary for converting the methyl halide to dimethyl ether) is greatly reduced.

[0412] The hydrogen halide stream obtained in step c) of the process is subjected to decomposition to release hydrogen and halogen for recovery. The halogen reactant may be recycled to steps a) and / or b) of the process, for example added to the feed stream supplied in step a) and / or supplied separately during reaction step b).

[0413] The preferred way to decompose the hydrogen halide is electrolysis. Therefore, this step of the process of the present invention is preferably carried out in an electrolysis cell, preferably in a polymer electrolyte membrane cell (PEM) containing at least a proton-conducting membrane. Polymer electrolyte membrane (PEM) electrolysis is well known in the art and includes cells equipped with a solid polymer electrolyte (SPE) that is responsible for the conduction of protons, the separation of gaseous products, and the electrical insulation of the electrodes.

[0414] In some embodiments of the invention, step e) of the process comprises the steps of supplying an aqueous solution of hydrogen halide to an electrolytic cell (such as defined herein) comprising a positive electrode and a negative electrode, and electrolytically decomposing the hydrogen halide by maintaining a potential between the electrodes of about 0.5 to 2.5 V.

[0415] In some embodiments of the present invention, step e) of the process comprises the steps of supplying an aqueous solution of hydrogen halide to an electrolytic cell (as defined herein) comprising a positive electrode and a negative electrode, and electrolytically decomposing the hydrogen halide by maintaining a current density between the electrodes of about 100 to 800 mA / cm2.

[0416] The potential required to decompose the hydrogen halide solution decreases as the temperature of the aqueous solution increases. It is particularly preferred to conduct the electrolytic decomposition at a temperature of about 20 to 95° C., and preferably about 40 to 80° C. The pressure in the electrolytic decomposition zone is maintained high enough to maintain the aqueous hydrogen halide in the liquid phase. Generally, the pressure will be in the range of about 0.1 to 5 MPa (1-50 bar).

[0417] The gaseous hydrogen (H ) stream produced in step e) of the process comprises at least 90.0 mol %, e.g., at least 95.0 mol %, or at least 99.0 mol %, or at least 99.5 mol %, or at least 99.9 mol % hydrogen. The hydrogen obtained by the process according to the invention can be used in downstream applications. For example, it can be used for ammonia synthesis, for hydrogenation purposes, for chemical synthesis, or for energy generation by combustion in a gas turbine (with or without additional hydrocarbon fuels). The produced hydrogen can also be used as a chemical feedstock to reduce dependence on oil and natural gas.

[0418] The halogen reactant (X2) produced in step e) of the process may be reused in step b) of the process, for example after suitable pretreatment such as purification and / or drying.

[0419] In some preferred embodiments, the halogen reactant (X2) obtained in step e) is purified, for example by condensation, before being returned to step b).

[0420] In some preferred embodiments, the halogen reactant (X2) obtained in step e) is dried before being returned to step b). Preferably, the halogen reactant (X2) is dried over a molecular sieve. Preferably, before the halogen reactant (X2) is returned to step b), the amount of water in the halogen reactant (X2) is at most 2000 ppm, preferably at most 1500 ppm, preferably at most 1000 ppm, preferably at most 750 ppm, preferably at most 500 ppm, wherein ppm is expressed as the weight of water relative to the total weight of the halogen reactant.

[0421] In some embodiments of the present invention, the process of the present invention further comprises the following step f): regenerating the metal halide (MX) formed in step d) into a metal oxide (MO) and a halogen reactant (X2).

[0422] The terms "regeneration" and "conversion" are used as synonyms in this context. The process preferably comprises recovering the metal oxide and the halogen reactant by contacting the metal halide (MX) obtained in step d) of the process with a regeneration agent capable of forming MO and the halogen reactant (X2).

[0423] The "regeneration agent" used in step f) of the process may include oxygen or air. For example, the process preferably comprises recovering the metal oxide and halogen reactant by contacting the metal halide (MX) obtained in step d) of the process with oxygen or air to form MO and the halogen reactant (X2). The specific amount of air or oxygen may depend on the particle size, the loading of the metal oxide on the solid support, and the selected regeneration temperature. Preferably, an excess of air or oxygen is used.

[0424] According to the present invention, it is preferred that step f) of the process is carried out at a temperature of at least 150° C., preferably at least 200° C., preferably at least 250° C., preferably at least 300° C., preferably at least 350° C., preferably at least 400° C. It is preferred that step f) of the process is carried out at a temperature of at most 1600° C., preferably at most 1400° C., preferably at most 1200° C., preferably at most 1000° C., preferably at most 800° C., preferably at most 600° C. For example, the temperature during step f) of the process is from at least 150° C. to at most 1600° C., preferably from at least 200° C. to at most 1400° C., preferably from at least 250° C. to at most 1200° C., preferably from at least 300° C. to at most 1000° C., preferably from at least 350° C. to at most 800° C., preferably from at least 400° C. to at most 600° C. Preferably, the temperature during step f) is maintained by the exothermic reaction in step f) and optionally by providing steam.

[0425] According to the present invention, it is preferred that step f) of the process is carried out at a pressure of at least 0.5 bar, preferably at least 0.8 bar, preferably at least 0.9 bar, preferably at least 1.0 bar, preferably at least 1.1 bar, preferably at least 5.0 bar, preferably at least 10.0 bar during step f). Preferably, step f) of the process is carried out at a pressure of at most 50.0 bar, preferably at most 45.0 bar, preferably at most 40.0 bar, preferably at most 35.0 bar, preferably at most 30.0 bar, preferably at most 25.0 bar, preferably at most 20.0 bar during step f). For example, the reaction pressure during step f) is from at least 0.5 bar to at most 50.0 bar, preferably from at least 0.8 bar to at most 45.0 bar, preferably from at least 0.9 bar to at most 40.0 bar, preferably from at least 1.0 bar to at most 35.0 bar, preferably from at least 1.1 bar to at most 30.0 bar, preferably from at least 5.0 bar to at most 25.0 bar, preferably from at least 10.0 bar to at most 20.0 bar, preferably from at least 10.0 bar to at most 15.0 bar.

[0426] In an example, the temperature during step b) is at least 300°C and at most 600°C, and the pressure during step b) is at least 5.0 bar and at most 30.0 bar. In another example, the temperature during step b) is between 380°C and 520°C, and the pressure during step b) is between 10.0 bar and 20.0 bar. In an example, the temperature during step d) is at least 100°C and at most 300°C, and the pressure during step d) is at least 2.0 bar and at most 20.0 bar. In another example, the temperature during step d) is between 120°C and 250°C, and the pressure during step d) is between 10.0 bar and 15.0 bar. In an example, the temperature during step f) is at least 300°C and at most 1000°C, and the pressure during step f) is at least 1.1 bar and at most 30.0 bar. In a further example, the temperature during step f) is comprised between 400°C and 600°C, and the pressure during step f) is comprised between 10.0 bar and 15.0 bar.

[0427] In some cases, the metal halide formed in step d) can be separated from the metal oxide to proceed to step f). During step d), it can also happen that the amount of solid metal oxide is depleted while the amount of metal halide on the solid support increases, thereby forming a mixture of metal oxide and metal halide on the solid support. In such a case, the mixture of metal oxide and metal halide formed on the solid support during step d) can be subjected to a regeneration step f).

[0428] The regeneration of the metal halide (MX) formed in step d) to metal oxide cannot be carried out simultaneously with the conversion of the methyl halide to dimethyl ether during this step. Therefore, in some embodiments, a portion of the solid support (e.g., a mixture comprising a metal halide and a metal oxide) can be separated or isolated from the reactor or reaction zone for regeneration in step f), while another portion is used to carry out step d). For example, multiple beds of solid metal oxide can be used so that one bed can be used for the formation of dimethyl ether in step d) while the other beds are regenerated in step g). In such embodiments, the reactor bed can alternatively undergo regeneration according to step f). The metal oxide obtained by the regeneration step can be reused in the process as the solid metal oxide in step d).

[0429] Regeneration results in the formation of a gaseous effluent comprising the halogen reactant, oxygen and optionally nitrogen. Preferably, the halogen reactant (X2) is isolated from the gaseous effluent by condensing the halogen reactant (X2) from the gaseous effluent. The halogen reactant obtained can also be reused in step b) of the process, for example after a suitable pretreatment (such as purification and / or drying).

[0430] In some preferred embodiments, the halogen reactant (X2) obtained in step f) is purified, for example by condensation, before being returned to step b).

[0431] In some preferred embodiments, the halogen reactant (X2) obtained in step f) is dried before returning to step b). Preferably, the halogen reactant (X2) is dried over a molecular sieve. Preferably, before the halogen reactant (X2) is returned to step b), the amount of water in the halogen reactant (X2) is at most 2000 ppm, preferably at most 1500 ppm, preferably at most 1000 ppm, preferably at most 750 ppm, preferably at most 500 ppm, wherein ppm is expressed as the weight of water relative to the total weight of the halogen reactant.

[0432] In some embodiments of the process according to the invention, polyhalogenated methanes are formed during step b) and may be separated during step c), as described above. In some embodiments, the process of the invention therefore further comprises the step of converting the polyhalogenated methanes (e.g. separated in step c)) into methanol, preferably by hydrogenating the polyhalogenated methanes to form methyl halides, followed by reacting the methyl halides with a solid metal hydroxide (MOH (s) ) under reaction conditions effective to produce the corresponding methanol.

[0433] Examples of suitable metal hydroxides for use in the present process include, but are not limited to, metal hydroxides selected from the list comprising or consisting of potassium hydroxide (KOH), sodium hydroxide (NaOH), barium hydroxide (Ba(OH)2), cesium hydroxide (CsOH), strontium hydroxide (Sr(OH)2), calcium hydroxide (Ca(OH)2), lithium hydroxide (LiOH), rubidium hydroxide (RbOH), magnesium hydroxide (Mg(OH)2), and any mixtures thereof. Preferred examples of solid metal hydroxides may be alkali metal hydroxides, such as preferably potassium hydroxide (KOH), lithium hydroxide (LiOH), sodium hydroxide (NaOH), or any mixtures thereof. A particularly preferred example is potassium hydroxide (KOH).

[0434] As used herein, the term "solid" refers to a metal hydroxide provided on a solid support, such as a silica or alumina support, more preferably a silica support. Preferably, the solid support is impregnated with the metal hydroxide. Preferably, the solid support is impregnated with a solution of the metal hydroxide and the impregnated solid support is then dried.

[0435] Examples of suitable reaction conditions include, for example, contacting the methyl halide with the solid metal hydroxide at a temperature between 120 and 250° C., at a pressure between 10 and 15 bar, and for at least 4 minutes and up to 6.0 minutes.

[0436] In some embodiments of the process according to the present invention, polyhalogenated methane is formed during step b) and may be separated during step c), as described above. In some embodiments, the process of the present invention therefore further comprises the step of converting the polyhalogenated methane (e.g., separated in step c)) into DME, preferably by hydrogenating the polyhalogenated methane to form a methyl halide, and subsequently contacting the methyl halide with a solid metal oxide, preferably a solid metal oxide as defined herein, under reaction conditions effective to produce DME, preferably under reaction conditions as defined herein.

[0437] In some embodiments of the present invention, unreacted methane may still be present in the effluent stream obtained in step b) of the process. In some embodiments of the present invention, unreacted methane may still be present in the methyl halide stream obtained in step c) of the process. In some embodiments of the present invention, unreacted methane may still be present in the stream of dimethyl ether obtained in step d) of this process. The remaining unreacted methane can be removed from the corresponding stream, for example, by distillation. In some preferred embodiments of the present invention, such removed unreacted methane can be recycled or fed to step a) and / or step b) of the process.

[0438] The present invention provides a system for producing dimethyl ether and hydrogen from methane, comprising:

[0439] - a halogenation reactor (1) configured to react a gaseous feed stream comprising methane with at least one halogen reactant (X2) to form an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX) and optionally unreacted methane,

[0440] - a separation system (2) fluidly connected to the halogenation reactor (1) and configured to receive an effluent stream from the halogenation reactor (1) and configured to separate a hydrogen halide (HX) stream and a methyl halide (MeX) stream from the effluent stream;

[0441] - a dimethyl ether synthesis reactor (3) fluidly connected to the separation system (2) and configured to receive a methyl halide stream from the separation system (2) and react the methyl halide stream with a solid metal oxide to form a metal halide (MX) and dimethyl ether (DME); and

[0442] - an electrolysis unit (4) comprising at least one electrolysis cell and a power source for supplying electric current to the electrolysis cell, the electrolysis cell being fluidly connected to the separation system (2) and configured to receive a hydrogen halide stream and to decompose the hydrogen halide stream into a gaseous hydrogen stream and a stream comprising a halogen reactant.

[0443] As used herein, the term "fluidically connected" or "fluidically connected" is used as a synonym in this article and is intended to refer to a connection between two components (or units or devices, etc.) of a system given herein such that a fluid can flow from one component (e.g., unit, device, reactor, etc.) to another through the connection. Preferably, two fluidically connected components are connected such that the outlet of a first component is connected to the inlet of a second component via a pipe, conduit, or series of pipes or conduits. Other components (e.g., separators, dryers, condensers, etc.) may be fluidically connected between the two fluidically connected components.

[0444] The terms "supply means" or "supply system" are used herein as synonyms and refer to a suitable system allowing the supply of streams, or reaction products, or reactants, and include, for example, pipes, conduits, supply lines, inlet lines, connecting lines, etc.

[0445] The term "recovery device" or "recovery system" is used herein as a synonym and refers to a suitable system that allows for the recovery of a stream or reaction products or reactants and includes, for example, pipes, recovery lines, outlet lines, connecting lines, etc. A "recovery device" or "recovery system" may include a separation device.

[0446] The term "transfer device" or "transfer system" is also used as a synonym in this document and refers to a suitable system that allows the transfer (transport) of streams or reaction products or reactants (for example, from one unit or reactor to another unit or reactor), and includes, for example, pipes, conduits, collection lines, outlet lines, connecting lines, etc.

[0447] The halogenation reactor (1) used in the system of the present invention can be any type of reactor suitable for allowing a gaseous feed stream comprising methane to react with a halogen reactant under appropriate conditions to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX).

[0448] In some preferred embodiments, the separation system (2) used in the system of the present invention comprises a quench tower or consists of a quench tower. In a preferred embodiment of the present invention, the separation system (preferably a quench tower) is equipped with an inlet system configured to supply an absorbent as defined herein to the system or tower.

[0449] The dimethyl ether synthesis reactor (3) used in the system of the present invention can be any type of reactor that is suitable for containing the solid metal oxide defined herein and allowing the (gaseous) methyl halide stream to react with the solid metal oxide under appropriate conditions to produce metal halide (MX) and dimethyl ether (DME).

[0450] In the example, the dimethyl ether synthesis reactor (3) is a swing-bed reactor. As used herein, the term "swing-bed reactor" is a reactor comprising at least two beds for containing solid metal oxides, the beds being arranged so that one bed can be regenerated while the other bed can be used to convert metal halides into dimethyl ether.

[0451] In another embodiment, the dimethyl ether synthesis reactor (3) comprises at least one, preferably at least two fluidized beds. In particular, when there are at least two fluidized beds, one bed can be stopped and regenerated while the other bed is still used to convert methyl halide into dimethyl ether.

[0452] The electrolysis unit (4) for use in the present invention comprises at least one electrolysis cell and a power supply for supplying electric current to the electrolysis cell. A particularly suitable electrolysis cell is a polymer electrolyte membrane cell (PEM) comprising at least one proton conducting membrane. One of the greatest advantages of PEM electrolysis is its ability to operate at high current densities. This can lead to reduced operating costs. Polymer electrolytes allow PEM electrolysis cells to operate with very thin membranes (~100-200 μm) while still allowing high voltages, resulting in low ohmic losses, which are primarily caused by proton conduction across the membrane (0.1 S / cm) and compressed hydrogen output. Due to its solid structure, polymer electrolyte membranes advantageously provide very high product gas purity.

[0453] The system according to the present invention may further comprise

[0454] - a feed stream supply system (5) for supplying a gaseous feed stream comprising methane to the halogenation reactor (1); and

[0455] - A halogen supply system (6) for supplying halogen reactant to the halogenation reactor (1).

[0456] Such a system for supplying reactants to the halogenation reactor may comprise an inlet line (conduit), which is optionally equipped with a control device to control the flow rate of the reactant stream to the reaction zone. In a preferred embodiment of the invention, separate devices (separate inlet lines or conduits) may be provided for each reactant in the process (i.e., being a gaseous feed stream and a halogen reactant separately).

[0457] The system according to the present invention may further comprise an effluent recovery system (10), such as a conduit or pipeline, configured to recover the effluent stream from the halogenation reactor (1) and adapted to feed the recovered effluent stream to a downstream separation system (2).

[0458] The system according to the present invention may further comprise

[0459] a hydrogen halide transfer system (12) configured to withdraw a hydrogen halide stream from the separation system (2) and to supply the withdrawn hydrogen halide stream to the electrolysis unit (4); and

[0460] - a methyl halide transfer system (11) configured to collect a methyl halide stream from the separation system (2) and supply the collected methyl halide stream to the dimethyl ether synthesis reactor (3).

[0461] Such a system for supplying reactants to or withdrawing reactants from the separation system may comprise an inlet line (conduit, pipe, pipeline), optionally provided with control means, for example for controlling the flow rate of the reactants to the reaction zone.

[0462] The system according to the present invention may further comprise an absorbent supply line (17) for supplying an aqueous absorbent, preferably an aqueous hydrogen halide (HX) solution, to the separation system (2). The absorbent supply line is, for example, an inlet line for supplying an absorbent, such as an aqueous hydrogen halide solution, to the separation zone.

[0463] The system according to the invention may also comprise a system for separately collecting the gaseous hydrogen stream and the stream containing the halogen reactant from the electrolysis unit. Such a system comprises in particular:

[0464] - a hydrogen recovery system (8) configured to recover a gaseous hydrogen stream from the electrolysis unit (4);

[0465] - a halogen recovery system (9) configured to recover the halogen reactant from the electrolysis unit (4);

[0466] Such a system for supplying reactants to or withdrawing reactants from the separation system may comprise an inlet line (conduit, pipe, pipeline), optionally provided with control means, eg for controlling the flow rate of the reactants to the reaction zone.

[0467] Optionally, the system of the present invention may be provided with means (20) (e.g., a transfer line or conduit) for returning the stream of halogen reactant collected from the electrolysis unit, or at least a portion thereof, to the halogenation reactor. This allows the halogen reactant to be reused in the system.

[0468] In some preferred embodiments, the means (20) for returning the stream of halogen reactant withdrawn from the electrolysis unit (4) or a portion thereof to the halogenation reactor (1) comprises one or more connecting lines (connecting pipes).

[0469] In some embodiments, the one or more connecting lines for returning the stream of halogen reactant to the halogenation reactor may be provided with one or more driers (e.g., molecular sieves) suitable for drying the stream of halogen reactant before feeding it to the halogenation reactor.

[0470] In some embodiments, the one or more connecting lines for returning the stream of halogen reactant to the halogenation reactor may be provided with one or more purification devices (such as, for example, one or more condensers) suitable for purifying the stream of halogen reactant before feeding the stream to the halogenation reactor.

[0471] Furthermore, the system of the present invention comprises a dimethyl ether recovery system (7) configured to recover a stream containing dimethyl ether from the dimethyl ether synthesis reactor (3).

[0472] In some embodiments of the present invention, polyhalogenated alkanes may be formed in step b) of the process. Such polyhalogenated alkanes may, for example, comprise methyl dihalide (CH2X2). Therefore, the system according to the present invention may, in some embodiments, comprise a polyhalogenated alkanes removal unit configured to receive an effluent stream from the halogenation reactor (1) and remove polyhalogenated alkanes from the effluent stream, thereby producing a polyhalogenated alkanes stream and a methyl halide stream.

[0473] Preferably, such a polyhalogenated alkane removal unit is arranged downstream of the halogenation reactor (1) and upstream of the separation system (2) and is connected, preferably fluidly connected, to the halogenation reactor (1) and the separation system (2), for example via connecting lines (15, 16).

[0474] The polyhalogenated alkane removal unit may, for example, comprise:

[0475] a separation system (13), such as a separation (e.g., distillation) column, configured to receive the effluent stream from the halogenation reactor (1) and to separate a polyhalogenated alkane stream from the effluent stream,

[0476] a supply system (15), such as a supply line or pipeline, configured to supply the effluent stream from the halogenation reactor (1) to the separation column, and

[0477] - A polyhalogenated alkane recovery system (14), such as an outlet line or pipeline, configured to recover the polyhalogenated alkane stream from the separation system (13).

[0478] The polyhalogenated alkane removal unit preferably further comprises a device (such as a transfer line or pipeline) for collecting a product stream (e.g., a product stream comprising methyl halide and hydrogen halide) from which the polyhalogenated alkanes defined herein have been removed. Preferably, such a device is configured to transfer the collected product stream to a downstream separation system to further separate the product stream, e.g., into a separate methyl halide stream and a separate hydrogen halide stream.

[0479] In some embodiments, the polyhalogenated alkane removal unit is capable of separating polyhalogenated alkanes from the effluent stream into a polyhalogenated methane stream and a polyhalogenated C 2+ In some embodiments, the polyhalogenated alkane removal unit includes a polyhalogenated methane outlet and a polyhalogenated C 2+ Alkane export.

[0480] In some embodiments of the invention, C as defined herein 2+ Alkyl monohalide may be formed in step b) of the process. Thus, in some embodiments, the system according to the present invention may further comprise C 2+ an alkyl monohalide removal unit configured to receive an effluent stream from the halogenation reactor (1) and remove C 2+ Alkyl monohalides.

[0481] In some embodiments, such C 2+ The alkyl monohalide removal unit is disposed downstream of the halogenation reactor (1) and upstream of the separation system (2), and is connected, preferably fluidly connected, to the halogenation reactor (1) and the separation system (2), for example, via a connecting line.

[0482] In some embodiments, C 2+ The alkyl monohalide removal unit may include, for example,

[0483] - a separation system, such as a separation (eg, distillation) column, configured to receive the effluent stream from the halogenation reactor (1) and to separate C from the effluent stream; 2+ Alkyl monohalide stream,

[0484] a supply system, such as a supply line or pipeline, configured to supply the effluent stream from the halogenation reactor (1) to the separation system, and

[0485] -C 2+ Alkyl monohalide recovery system, such as an outlet line or pipeline, configured to extract the alkyl monohalide from the C 2+ Alkyl separation system collects C 2+ Alkyl monohalide stream.

[0486] C 2+The alkyl monohalide removal unit preferably further comprises means, such as a transfer line or pipeline, for collecting a product stream (e.g., a product stream comprising methyl halide and hydrogen halide) from which C 2+ Preferably, such an apparatus is configured to transfer the recovered product stream to a downstream separation system for further separation of the product stream, for example into a separate methyl halide stream and a separate hydrogen halide stream.

[0487] In some embodiments of the present invention, the system further comprises

[0488] a supply line (18) configured to supply a regeneration agent as defined herein to the dimethyl ether synthesis reactor (3), said regeneration agent being capable of converting the metal halide (MX) formed in said dimethyl ether synthesis reactor into a metal oxide (MO) and a halogen reactant (X2);

[0489] - an outlet line (19) configured to remove from the dimethyl ether synthesis reactor an effluent stream comprising the halogen reactant (X2) produced during said conversion reaction.

[0490] By providing the above named elements, the present system enables the regeneration (harvesting) of solid metal oxide within the same system. This avoids the need for a delivery system for supplying fresh solid metal oxide to the system and process and therefore also improves process sustainability and efficiency.

[0491] Optionally, the system of the present invention may be further provided with a separating device for separating the halogen reactant from the effluent stream comprising the halogen reactant (X2) produced during the conversion (regeneration) reaction. Suitable separating devices for separating the halogen reactant from the effluent stream may include, but are not limited to, one or more condensers.

[0492] In some preferred embodiments, the system further provides a device (19, 20) for returning the logistics of the halogen reactant collected from the dimethyl ether synthesis reactor (3) to the halogenation reactor (1). In some preferred embodiments, the device (19) for returning the halogen reactant collected from the dimethyl ether synthesis reactor (3) to the halogenation reactor (1) includes one or more connecting pipelines (connecting pipes). In some embodiments, the one or more connecting pipelines for returning the logistics of the halogen reactant to the halogenation reactor may be provided with one or more dryers (such as molecular sieves, etc.), which are suitable for drying the logistics of the halogen reactant before the logistics is fed to the halogenation reactor. In some embodiments, the one or more connecting pipelines for returning the logistics of the halogen reactant to the halogenation reactor may be provided with one or more purification devices (such as, for example, one or more condensers), which are suitable for purifying the logistics of the halogen reactant before the logistics is fed to the halogenation reactor.

[0493] In some embodiments of the present invention, unreacted methane may still be present in the effluent stream obtained in step b) of the process. In some embodiments of the present invention, unreacted methane may still be present in the methyl halide stream obtained in step c) of the process. In some embodiments of the present invention, unreacted methane may still be present in the dimethyl ether stream obtained in steps d) and / or f) of the present process. The remaining unreacted methane can be removed from the corresponding stream, for example by distillation. Therefore, the present system further provides the following apparatus: such as a distillation tower, etc., for removing, preferably distilling, unreacted methane from the above-mentioned stream. In a particularly preferred embodiment of the present invention, the following system is provided: wherein the distillation tower is configured to be fluidically connected to the dimethyl ether collection system (7).

[0494] The following examples are only used to illustrate the present invention and should not be construed as limiting its scope in any way. Although the present invention is only illustrated in some of its forms, it will be apparent to those skilled in the art that the present invention is not limited thereto, but is prone to various changes and modifications without departing from the scope of the present invention.

[0495] Example

[0496] Example 1

[0497] refer to Figure 1 , the following examples illustrate embodiments of processes according to the present invention, and systems for carrying out such embodiments according to the present invention.

[0498] Figure 1The system shown in FIG comprises a halogenation reactor ( 1 ), a separation system ( 2 ), a dimethyl ether synthesis reactor ( 3 ) and an electrolysis unit ( 4 ).

[0499] According to this embodiment, a gaseous feed stream comprising methane is introduced into a halogenation reactor (1) via a feed stream supply line (5). A halogen reactant (e.g., Br2) is also introduced into the halogenation reactor (1) via a separate halogen reactant supply line (6). The gaseous feed stream comprising methane reacts with the halogen reactant (X2) in the halogenation reactor to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX). Optionally, unreacted methane remains in the effluent stream.

[0500] The effluent stream obtained leaves the halogenation reactor (1) through a suitable collection pipeline (10) and is fed to a separation system (2) arranged downstream of the halogenation reactor via the pipeline. In the separation system, the effluent stream is further separated into a hydrogen halide (HX) stream and a methyl halide (MeX) stream; the hydrogen halide (HX) stream is collected from the separation unit and fed to the electrolysis unit (4) via a suitable connecting pipeline (12), and the methyl halide (MeX) stream is collected from the separation system and fed to the dimethyl ether synthesis reactor (3) via a suitable connecting pipeline (11).

[0501] In the dimethyl ether synthesis reactor (3), a methyl halide (MeX) stream reacts with a solid metal oxide, thereby forming dimethyl ether (DME). A stream comprising dimethyl ether can be recovered from the dimethyl ether synthesis reactor (3) via a dimethyl ether recovery line (7).

[0502] In the electrolysis unit (4), the hydrogen halide (HX) stream flowing out of the separation system is further decomposed into a stream of hydrogen gas (H2) and a stream of halogen reactant (X2); the stream of hydrogen gas (H2) is removed from the electrolysis unit via an outlet pipeline (8), and the stream of halogen reactant (X2) is removed from the electrolysis unit via an outlet pipeline (9).

[0503] Example 2

[0504] refer to Figure 2 The following examples illustrate another embodiment of a process according to the present invention, as well as a system for carrying out such an embodiment according to the present invention.

[0505] Figure 1 The system shown in FIG comprises a halogenation reactor (1), a separation system (2), a dimethyl ether synthesis reactor (3), an electrolysis unit (4) and a polyhalogenated alkane removal unit (13).

[0506] A gaseous feed stream containing about 100 mol% (CH4) of methane is introduced into the halogenation reactor (1) via a feed stream supply line (5) at a flow rate of about 1604 kg / hr. A halogen reactant (X2), in this case bromine (Br2), is introduced into the halogenation reactor (1) via a halogen reactant supply line (6) at a rate of about 5274 kg / hr. The halogenation reactor (1) is maintained at a temperature of about 300-600°C and a pressure of 5 to 30 bar.

[0507] An effluent stream comprising unreacted methane (CH), hydrogen halide (HX), methyl halide (MeX), and polyhalogenated alkanes (e.g., CHX) is withdrawn from the halogenation reactor (1) via outlet (15) and fed to a polyhalogenated alkane removal unit comprising a separation column (13). The separation column separates polyhalogenated alkanes (e.g., CHX) (e.g., CHBr) from the effluent stream and removes polyhalogenated alkanes (e.g., CHX) from the system via a polyhalogenated alkane outlet line (14) at a rate of approximately 860 kg / hr.

[0508] A residual gaseous stream substantially free of polyhalogenated alkanes (e.g., CH2X2) is withdrawn from the polyhalogenated alkane removal unit (13) and then fed via connecting line (16) to a separation system (2) comprising a quench tower. In the quench tower, the residual gaseous stream is contacted with an aqueous absorbent, specifically, in this example, a 26.7 wt% aqueous HBr solution, at a flow rate of approximately 13,800 kg / hr. The absorbent captures gaseous hydrogen halide (HX) from the effluent stream, and the resulting solution exits the separation system (2) as a liquid stream via a hydrogen halide outlet line (12).

[0509] The remaining gaseous stream, essentially comprising methyl halide (MeX), and optionally some unreacted methane (CH4), leaves the separation system (2) via outlet line (17) and is fed to the DME synthesis reactor (3). In this embodiment, the DME synthesis reactor (3) is a swing bed reactor filled with a porous γ-alumina (MO (s) The dimethyl ether synthesis reactor (3) is maintained at a temperature of about 100-300°C and a pressure of 2 to 30 bar.

[0510] In the dimethyl ether synthesis reactor (3), methyl halide (MeX) is converted into dimethyl ether (DME), which is collected together with optional unreacted methane (CH4) through a dimethyl ether outlet (7). Dimethyl ether is produced at a rate of about 740 kg / hr and can be separated from unreacted methane by techniques known in the art, such as distillation using a distillation column.

[0511] The hydrogen halide (HX) liquid stream leaving the separation system is sent to the electrolysis unit (4) via the hydrogen halide outlet line (12), wherein the hydrogen halide (HX) decomposes into hydrogen gas (H2) and halogen reactant (X2), in this embodiment Br2. The hydrogen gas (H2) produced can be collected via the hydrogen gas outlet line (8) and optionally dried. The halogen reactant (X2) produced can also be collected via the outlet line (9), optionally dried, and returned to the halogenation reactor (1) for reuse.

[0512] According to the present process, it is possible that the reactants (in this embodiment, calcium magnesium oxide (MO (s) )) is depleted, i.e., excessive (MX (s) In such a case, the reactor bed can be regenerated by treatment with a regeneration agent (18) comprising air (comprising O2 and N2) at a temperature of 300 to 1000°C and a pressure of 1.1 to 30 bar. This regeneration treatment results in the formation of a metal oxide (MO) and a halogen reactant (X2).

[0513] The gaseous effluent generated during such a regeneration process comprises nitrogen (N2), oxygen (O2) and halogen reactant (X2) and can leave the hydrogenation reactor (3) via an effluent outlet (19). The halogen reactant (X2) can then be separated from the effluent, for example by condensation, dried, and returned to the halogenation reactor (1) for reuse in the system.

[0514] Example 3

[0515] This example illustrates a halogenation step that can be used in the process of the present invention.

[0516] In this example, the experimental setup consisted of a quartz reactor and a glass syringe (Sigma Aldrich) for liquid bromine supply. A methane supply (5.0, Praxair) with a Bronkhorst mass flow controller was established.

[0517] The feed rate was maintained to give a residence time of about 0.01 seconds for the reactants in the heated zone of the reactor and a CH4 / Br2 molar ratio of about 3 / 1. The heated zone of the reactor was maintained at a temperature of about 370°C and a pressure of about 3 bar.

[0518] The effluent from the reactor was then first passed through a cold trap (10° C.) to condense CH 2 Br 2 produced during the reaction and traces of unreacted bromine.

[0519] In this experiment, the effluent from the reactor was passed through an aqueous caustic bubbler to remove the major amount of HBr, and the remaining stream was then sent to an Agilent GC with a SilicaPlot column and a FID detector for analysis.

[0520] Based on the GC data, the conversion of methane to methyl bromide (with CH2Br2 as a byproduct) was calculated using the following formula:

[0521]

[0522]

[0523]

[0524] x(CH4) = 29%,

[0525] s(CH3Br) = 89%,

[0526] s(CH2Br2)=9%.

[0527] Where n = molar mass, x = conversion, and s = selectivity

[0528] Example 4

[0529] The following examples illustrate the dimethyl ether synthesis reaction steps that can be used in the process of the present invention.

[0530] In this embodiment, the experimental setting includes the use of a vertical quartz reactor (20 mm ID) connected to a GC. Methyl bromide (>99.9%, Mebrom) is fed by a piston pump. The reactor is filled with 240 grams of a mixed calcium magnesium oxide sample deposited on porous gamma-alumina, pre-calcined before testing. During the entire experiment, the temperature of the reactor remains at 120°C and 5.5 bar. During the experiment, the flow velocity of 25 g / h of CH Br and the flow velocity of 280 mL / min of N 2 are used. During the 4-hour run, CH Br appears to be stable to the conversion of dimethyl ether.

[0531] Based on the GC data, the conversion of methyl bromide to dimethyl ether was calculated using the following formula:

[0532]

[0533]

[0534] Where x(CH3Br) is greater than 45%, and s(DME) = 83%; where n = molar amount, x = conversion, and s = selectivity.

Claims

1. A process for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising the following steps: a) providing a gaseous feed stream comprising methane; b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX), optionally polyhalogenated alkane, and optionally unreacted methane; c) separating from the effluent stream obtained in step b) the following: i) a methyl halide (MeX) stream, optionally comprising unreacted methane; and, ii) an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream; d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and, e) decomposing said aqueous hydrogen halide (HX) stream or said hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2); Wherein, in step c), the hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising said hydrogen halide with an aqueous absorbent or by distillation, thereby forming an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream, respectively.

2. The process according to claim 1, wherein the process further comprises the step of separating the polyhalogenated alkanes formed in step b) from the effluent stream.

3. The process of claim 2, wherein the step of separating the polyhalogenated alkanes is performed before separating the methyl halide (MeX) stream and the hydrogen halide stream from the effluent stream.

4. The process for producing dimethyl ether (DME) and hydrogen (H2) from methane according to claim 1, comprising the following steps: a) providing a gaseous feed stream comprising methane; b) reacting the gaseous feed stream with at least one halogen reactant (X2) under reaction conditions effective to produce an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX), polyhalogenated alkanes, and optionally unreacted methane; c) separating from the effluent stream obtained in step b) the following: i) a methyl halide (MeX) stream, which optionally comprises unreacted methane; and, ii) an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream; iii) a polyhalogenated alkane stream; d) mixing the methyl halide (MeX) stream separated in step c) with a solid metal oxide (MO (s) ) under reaction conditions effective to produce a metal halide (MX) and dimethyl ether (DME); and, e) decomposing said aqueous hydrogen halide (HX) stream or said hydrogen halide (HX) stream separated in step c) by electrolysis under conditions effective to produce a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2); Wherein, in step c), the hydrogen halide (HX) stream is separated from the effluent stream by contacting the effluent stream comprising said hydrogen halide with an aqueous absorbent or by distillation, thereby forming an aqueous hydrogen halide (HX) stream or a hydrogen halide (HX) stream, respectively.

5. The process according to any one of claims 1 to 4, wherein the polyhalogenated alkanes comprise polyhalogenated methane and optionally polyhalogenated C 2+ Alkane.

6. A process according to any one of claims 1 to 5, wherein the halogen reactant is selected from bromine (Br2), chlorine (Cl2), fluorine (F2), iodine (I2) and astatine (At2).

7. A process according to any one of claims 1 to 6, wherein the halogen reactant is bromine (Br2).

8. The process according to any one of claims 1 to 7, wherein the aqueous absorbent used in step c) is an aqueous hydrogen halide (HX) solution.

9. The process according to any one of claims 1 to 8, wherein C 2+ The alkyl monohalide is formed during step b).

10. The process according to any one of claims 1 to 9, wherein the process comprises separating the C formed in step b) of the process from the effluent stream. 2+ Alkyl monohalide step.

11. The process according to claim 10, wherein the process comprises separating the C formed in step b) from the effluent stream before separating the methyl halide (MeX) stream and the hydrogen halide stream from the effluent stream. 2+ Alkyl monohalides.

12. The process of any one of claims 1 to 11, wherein the gaseous feed stream comprises at least 75.0 vol. % methane, based on the total volume of the gaseous feed stream.

13. The process of any one of claims 1 to 12, wherein the gaseous feed stream comprises at least 99.9 vol. % methane, based on the total volume of the gaseous feed stream.

14. The process according to any one of claims 1 to 13, wherein the gaseous feed stream used in step a) of the process is substantially free of sulphur species.

15. The process according to any one of claims 1 to 14, wherein the gaseous feed stream used in step a) of the process contains less than 1.0 mol% of sulfur species.

16. The process according to any one of claims 1 to 15, wherein the gaseous feed stream used in step a) of the process contains less than 0.00001 mol% of sulfur species.

17. The process according to any one of claims 1 to 16, wherein the solid metal oxide (MO (s) ) is a metal oxide provided on a solid support.

18. The process of claim 17, wherein the solid support is a silica or alumina support.

19. The process according to any one of claims 1 to 18, wherein the process further comprises the following steps: f) regenerating the metal halide (MX) into a metal oxide (MO) and a halogen reactant (X2), thereby forming a metal oxide (MO) and a halogen reactant (X2).

20. The process according to claim 19, wherein step (f) is performed by contacting the metal halide (MX) with oxygen (O2) or air.

21. The process according to any one of claims 1 to 20, further comprising the step of returning the halogen reactant (X2) obtained in step e) and / or step f) of the process to step b).

22. The process according to any one of claims 1 to 21, wherein the gaseous hydrogen (H2) stream produced in step e) comprises at least 90.0 mol% hydrogen.

23. The process according to any one of claims 1 to 22, wherein the gaseous hydrogen (H2) stream produced in step e) comprises at least 99.9 mol% hydrogen.

24. The process according to any one of claims 1 to 23, wherein the process further comprises the step of removing unreacted methane from the dimethyl ether produced in step d).

25. The process of claim 24, wherein the step of removing unreacted methane from the dimethyl ether produced in step d) is a step of distilling unreacted methane from the dimethyl ether produced in step d).

26. The process of claim 24 or 25, wherein the process further comprises the step of recycling or feeding the removed unreacted methane into step a) and / or step b) of the process.

27. A system for producing dimethyl ether (DME) and hydrogen (H2) from methane, comprising: - a halogenation reactor (1) configured to react a gaseous feed stream comprising methane with at least one halogen reactant (X2) to form an effluent stream comprising methyl halide (MeX) and hydrogen halide (HX) and optionally unreacted methane, - a separation system (2) fluidly connected to the halogenation reactor (1) and configured to receive an effluent stream from the halogenation reactor (1) and configured to separate a hydrogen halide (HX) stream and a methyl halide (MeX) stream from the effluent stream; - a dimethyl ether synthesis reactor (3) which is fluidically connected to the separation system (2) and is configured to receive a methyl halide (MeX) stream from the separation system (2) and to combine the methyl halide (MeX) stream with a solid metal oxide (MO (s) ) to form a metal halide (MX) and dimethyl ether (DME); and - an electrolysis unit (4) comprising at least one electrolysis cell and a power source for supplying electric current to the electrolysis cell, the electrolysis cell being fluidically connected to the separation system (2) and configured to receive a hydrogen halide (HX) stream and to decompose the hydrogen halide (HX) stream into a gaseous hydrogen (H2) stream and a stream comprising a halogen reactant (X2); - a feed stream supply system (5) for supplying a gaseous feed stream comprising methane to the halogenation reactor (1); - a halogen supply system (6) for supplying a halogen reactant (X2) to the halogenation reactor (1); - an effluent collection system (10) configured to collect an effluent stream from the halogenation reactor (1) and feed the collected effluent stream to the separation system (2); - a dimethyl ether recovery system (7) configured to recover a stream containing dimethyl ether (DME) from the dimethyl ether synthesis reactor (3); - a hydrogen recovery system (8) configured to recover a gaseous hydrogen (H2) stream from the electrolysis unit (4); - a halogen recovery system (9) configured to recover the halogen reactant (X2) from the electrolysis unit (4); - a hydrogen halide transfer system (12) configured to collect a hydrogen halide (HX) stream from the separation system (2) and supply the collected hydrogen halide (HX) stream to the electrolysis unit (4); - a methyl halide transfer system (11) configured to collect a methyl halide (MeX) stream from the separation system (2) and supply the collected methyl halide (MeX) stream to a dimethyl ether synthesis reactor (3).

28. The system according to claim 27, wherein the system further comprises an absorbent supply line (17) for supplying aqueous absorbent to the separation system (2).

29. The system of claim 28, wherein the aqueous absorbent is an aqueous hydrogen halide (HX) solution.

30. The system according to any one of claims 27 to 29, wherein the system further comprises a polyhalogenated alkane removal unit configured to receive the effluent stream from the halogenation reactor (1) and remove polyhalogenated alkanes from the effluent stream.

31. The system according to any one of claims 27 to 30, wherein the system further comprises C 2+ an alkyl monohalide removal unit configured to receive an effluent stream from the halogenation reactor (1) and remove C 2+ Alkyl monohalides.

Images