C ₂ H ₆ + C0 ₂ QUENCH REACTIONS

TECHNICAL FIELD

[0001] The present disclosure relates to methods of producing olefins, more specifically methods of producing ethylene by integrating hydrocarbon pyrolysis with thermal quenching via endothermic reactions.

BACKGROUND

[0002] Hydrocarbons, and specifically olefins such as ethylene, can be typically used to produce a wide range of products, for example, polymers used in break-resistant containers and packaging materials. Currently, for industrial scale applications, ethylene is produced by heating natural gas condensates and petroleum distillates, which include ethane and higher hydrocarbons, and the produced ethylene is separated from a product mixture by using gas separation processes. However, some ethylene production processes also yield a large amount of carbon dioxide. Thus, there is an ongoing need for the development of processes for the production of olefins such as ethylene, as well as a reduction in carbon dioxide emissions.

BRIEF SUMMARY

[0003] Disclosed herein is a process for producing ethylene comprising (a) introducing a fuel gas stream and an oxidant gas to a combustion zone to produce a combustion product, (b) introducing a first reactant mixture comprising hydrocarbons and at least a portion of the combustion product to a first reaction zone to produce a pyrolysis reaction product via a pyrolysis reaction, wherein the combustion product heats the hydrocarbons to a first temperature effective for the pyrolysis reaction, and wherein the pyrolysis reaction product comprises unconverted hydrocarbons, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (¾), carbon dioxide (C0 ₂ ), and optionally ethylene (C ₂ H ₄ ), (c) cooling at least a portion of the pyrolysis reaction product in a quench zone to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature, and wherein the second temperature is lower than the first temperature, (d) introducing a second reactant mixture comprising ethane (C ₂ H ₆ ) and at least a portion of the cooled pyrolysis reaction product to a second reaction zone to produce a second product mixture, wherein the second reaction zone excludes a catalyst, wherein at least a portion of C ₂ H ₆ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ , wherein at least a portion of the C0 ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO, wherein the second product mixture comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , and unconverted hydrocarbons, wherein an amount of C ₂ H ₄ in the second product mixture is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, wherein the second product mixture is characterized by a third temperature, and wherein the third temperature is lower than the second temperature, (e) separating at least a portion of the second product mixture into an ethylene and acetylene stream and a carbon dioxide stream, wherein the ethylene and acetylene stream comprises C ₂ H ₄ , C ₂ H ₂ , CO, H ₂ , and unconverted hydrocarbons and (f) recycling at least a portion of the carbon dioxide stream to the second reaction zone.

[0004] Also disclosed herein is a process for producing ethylene and methanol comprising (a) introducing a fuel gas stream and an oxidant gas to a combustion zone to produce a combustion product, (b) separating a natural gas stream into methane (CH ₄ ) and ethane (C ₂ H ₆ ), (c) introducing a first reactant mixture comprising at least a portion of the CH ₄ and at least a portion of the combustion product to a first reaction zone to produce a pyrolysis reaction product via a pyrolysis reaction, wherein the combustion product heats the CH ₄ to a first temperature of equal to or greater than about 2,500 °C, wherein the first reaction zone excludes a catalyst, and wherein the pyrolysis reaction product comprises unconverted methane, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (H ₂ ), carbon dioxide (C0 ₂ ), and optionally ethylene (C ₂ H ₄ ), (d) cooling at least a portion of the pyrolysis reaction product in a quench zone to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature of from about 800 °C to about 1,000 °C, (e) introducing a second reactant mixture comprising at least a portion of the C ₂ H ₆ and at least a portion of the cooled pyrolysis reaction product to a second reaction zone to produce a second product mixture, wherein the second reaction zone excludes a catalyst, wherein at least a portion of C ₂ H ₆ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ , wherein at least a portion of the C0 ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO, wherein the second product mixture comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , unconverted methane, and unconverted ethane, wherein an amount of C ₂ H ₄ in the second product mixture is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, and wherein the second product mixture is characterized by a third temperature of less than about 200 °C, (f) separating at least a portion of the second product mixture into an ethylene and acetylene stream and a carbon dioxide stream, wherein the ethylene and acetylene stream comprises C ₂ H ₄ , C ₂ H ₂ , CO, H ₂ , unconverted methane, and unconverted ethane, (g) recycling at least a portion of the carbon dioxide stream to the second reaction zone, (h) introducing at least a portion of the ethylene and acetylene stream and a polar aprotic solvent to a third reaction zone to produce a third reaction zone effluent via hydrogenation to C ₂ H ₄ of at least a portion of the C ₂ H ₂ in the ethylene and acetylene stream, wherein the third reaction zone comprises an acetylene hydrogenation catalyst, wherein the third reaction zone effluent comprises C ₂ H ₄ , CO, H ₂ , unconverted methane, and unconverted ethane, and wherein an amount of C ₂ H ₄ in the third reaction zone effluent is greater than an amount of C ₂ H ₄ in the ethylene and acetylene stream, (i) separating at least a portion of the third reaction zone effluent into an ethylene stream, a syngas stream, an unconverted methane stream, and an unconverted ethane stream, wherein the syngas stream comprises H ₂ and CO and (j) introducing at least a portion of the syngas stream to a fourth reaction zone comprising a methanol production catalyst to produce a methanol stream.

[0005] Further disclosed herein is a process for producing ethylene comprising (a) combusting methane (CH ₄ ) and oxygen (0 ₂ ) to produce a combustion product at a first temperature of equal to or greater than about 2,500 °C, (b) pyrolyzing CH ₄ in the presence of at least a portion of the combustion product in a first reaction zone at the first temperature of equal to or greater than about 2,500 °C to produce a pyrolysis reaction product, wherein the pyrolysis reaction product comprises unconverted methane, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (H ₂ ), carbon dioxide (C0 ₂ ), and optionally ethylene (C ₂ H ₄ ), (c) cooling at least a portion of the pyrolysis reaction product from the first temperature of equal to or greater than about 2,500 °C to a second temperature effective for endothermic reactions of C ₂ H ₆ dehydrogenation and C0 ₂ hydrogenation to produce a cooled pyrolysis reaction product, wherein the second temperature is from about 800 °C to about 1 ,000 °C, and wherein the cooled pyrolysis reaction product comprises unconverted methane, C ₂ H ₂ , CO, H ₂ , C0 ₂ , and optionally C ₂ H ₄ , (d) at a temperature of from about 800 °C to about 1 ,000 °C, concurrently (i) dehydrogenating ethane (C ₂ H ₆ ) to produce C ₂ H ₄ and H ₂ ; (ii) hydrogenating at least a portion of C0 ₂ present in the cooled pyrolysis reaction product to produce CO; and (iii) comproportionating C ₂ H ₆ and at least a portion of the C ₂ H ₂ present in the cooled pyrolysis reaction product to produce C ₂ H ₄ ; wherein (i), (ii), and (iii) yield a combined reaction product, and wherein the combined reaction product comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , unconverted methane, and unconverted ethane and (e) separating C ₂ H ₄ from the combined reaction product. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] For a detailed description of the preferred aspects of the disclosed methods, reference will now be made to the accompanying drawing in which:

[0007] Figure 1 displays a schematic of an ethylene production system.

DETAILED DESCRIPTION

[0008] Disclosed herein are processes for producing ethylene comprising (a) introducing a fuel gas stream and an oxidant gas to a combustion zone to produce a combustion product; (b) introducing a first reactant mixture comprising hydrocarbons and at least a portion of the combustion product to a first reaction zone to produce a pyrolysis reaction product via a pyrolysis reaction, wherein the combustion product heats the hydrocarbons to a first temperature effective for the pyrolysis reaction, and wherein the pyrolysis reaction product comprises unconverted hydrocarbons, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (H ₂ ), carbon dioxide (C0 ₂ ), and optionally ethylene (C ₂ H ₄ ); (c) cooling at least a portion of the pyrolysis reaction product in a quench zone to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature, and wherein the second temperature is lower than the first temperature; (d) introducing a second reactant mixture comprising ethane (C ₂ H ₆ ) and at least a portion of the cooled pyrolysis reaction product to a second reaction zone to produce a second product mixture, wherein the second reaction zone excludes a catalyst, wherein at least a portion of C ₂ H ₆ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ , wherein at least a portion of the C0 ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO, wherein the second product mixture comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , and unconverted hydrocarbons, wherein an amount of C ₂ H ₄ in the second product mixture is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, wherein the second product mixture is characterized by a third temperature, and wherein the third temperature is lower than the second temperature; (e) separating at least a portion of the second product mixture into an ethylene and acetylene stream and a carbon dioxide stream, wherein the ethylene and acetylene stream comprises C ₂ H ₄ , C ₂ H ₂ , CO, H ₂ , and unconverted hydrocarbons; and (f) recycling at least a portion of the carbon dioxide stream to the second reaction zone.

[0009] Hydrocarbons pyrolysis (e.g., methane pyrolysis) generally converts methane at elevated temperatures (e.g., greater than about 2,000 °C) to a mixture of acetylene, carbon monoxide and hydrogen. Oxidative pyrolysis of methane is accompanied by exothermic oxidation reactions, according to reactions (1) and (2):

CH ₄ + 1.50 ₂ = CO + 2H ₂ 0 (ΔΗ = -1 14 kcal/mol; exothermic) (1) CH ₄ + 20 ₂ = C0 ₂ + 2H ₂ 0 (ΔΗ = -192 kcal/mol; exothermic) (2)

[0010] The heat generated by reactions (1) and (2) can be further used for cracking of methane, according to reaction (3):

2CH ₄ = C ₂ H ₂ + 3H ₂ (ΔΗ = 45 kcal/mol; endothermic) (3)

[0011] The processes disclosed herein integrate methane pyrolysis with hydrogenation of carbon dioxide produced as outlined in reaction (2) to carbon monoxide according to reaction (4), which carbon dioxide hydrogenation occurs simultaneously with ethane dehydrogenation to ethylene, according to reaction (5):

H ₂ + C0 ₂ = CO + H ₂ 0 (4) C ₂ H ₆ = C ₂ H ₄ + H ₂ (5)

[0012] Ethane dehydrogenation (reaction (5)) generally requires elevated temperatures for high conversion of ethane, such as temperatures above 700 °C. As will be appreciated by one of skill in the art, and with the help of this disclosure, both reactions (4) and (5) are endothermic reactions. Since reactions (4) and (5) require heat input, reactions (4) and (5) can utilize a portion of the heat produced by reactions (1) and (2). Carbon dioxide hydrogenation reaction (4) is a reversible reaction, which leads to the production of a product mixture (e.g., second product mixture) comprising carbon monoxide and water, as well as carbon dioxide and hydrogen, in addition to ethylene produced by reaction (5), unreacted ethane, and acetylene produced via reaction (3). The hydrogen produced via reaction (5) can drive the carbon dioxide hydrogenation according to reaction (4), which is a reverse water gas shift reaction.

[0013] Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as modified in all instances by the term "about." Various numerical ranges are disclosed herein. Because these ranges are continuous, they include every value between the minimum and maximum values. The endpoints of all ranges reciting the same characteristic or component are independently combinable and inclusive of the recited endpoint. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations. The endpoints of all ranges directed to the same component or property are inclusive of the endpoint and independently combinable. The term "from more than 0 to an amount" means that the named component is present in some amount more than 0, and up to and including the higher named amount.

[0014] The terms "a," "an," and "the" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. As used herein the singular forms "a," "an," and "the" include plural referents.

[0015] As used herein, "combinations thereof is inclusive of one or more of the recited elements, optionally together with a like element not recited, e.g., inclusive of a combination of one or more of the named components, optionally with one or more other components not specifically named that have essentially the same function. As used herein, the term "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0016] Reference throughout the specification to "an aspect," "another aspect," "other aspects," "some aspects," and so forth, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the aspect is included in at least an aspect described herein, and may or may not be present in other aspects. In addition, it is to be understood that the described element(s) can be combined in any suitable manner in the various aspects.

[0017] As used herein, the terms "inhibiting" or "reducing" or "preventing" or "avoiding" or any variation of these terms, include any measurable decrease or complete inhibition to achieve a desired result.

[0018] As used herein, the term "effective," means adequate to accomplish a desired, expected, or intended result.

[0019] As used herein, the terms "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "include" and "includes") or "containing" (and any form of containing, such as "contain" and "contains") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0020] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art.

[0021] Compounds are described herein using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash ("-") that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through the carbon of the carbonyl group.

[0022] Referring to Figure 1, an ethylene production system 1000 is disclosed. The ethylene production system 1000 generally comprises a combustion zone 1 10; a first reaction zone 120 (e.g., pyrolysis or cracking zone); a quench zone 130; a second reaction zone 140 (e.g., ethane dehydrogenation and carbon dioxide hydrogenation endothermic quench reactions zone); a first separation unit 200; a third reaction zone 300 (e.g., liquid phase hydrogenation reaction zone); and a second separation unit 400. As will be appreciated by one of skill in the art, and with the help of this disclosure, ethylene production system components shown in Figure 1 can be in fluid communication with each other (as represented by the connecting lines indicating a direction of fluid flow) through any suitable conduits (e.g., pipes, streams, etc.).

[0023] In an aspect, the process for producing ethylene as disclosed herein can comprise introducing a fuel gas stream 10 (e.g., methane stream) and an oxidant gas 1 1 to the combustion zone 1 10 to produce a combustion product.

[0024] Impurities and contaminants can be removed from the fuel gas stream 10 and/or a hydrocarbon stream 15 prior to introducing to the combustion zone 110 and/or the first reaction zone 120, respectively. In some aspects, the fuel gas stream 10 and the hydrocarbon stream 15 can be the same (e.g., can comprise the same hydrocarbons, for example can be portions of the same gas stream feedstock). In other aspects, the fuel gas stream 10 and the hydrocarbon stream 15 can be the different (e.g., can comprise different hydrocarbons, for example originating from different upstream sources). In yet other aspects, a portion (e.g., stream 15) of the fuel gas stream 10 can be fed to the first reaction zone 120 to provide hydrocarbons thereto.

[0025] The fuel gas stream 10 and/or the hydrocarbon stream 15 can comprise methane (CH ₄ ), ethane (C ₂ H ₆ ), propane, natural gas, natural gas liquids, associated gas, well head gas, enriched gas, heavy hydrocarbons, petcoke, naphtha, heavy oil, heavy oil residue, and the like, or combinations thereof. Generally, natural gas is a naturally occurring hydrocarbon gas mixture comprising mostly methane, but commonly including varying amounts of other higher alkanes, such as ethane, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, helium, etc. Heavy oil residues generally comprise polyalkylbenzenes such as polyethylbenzenes (PEBs), and well as multi-ring compounds. Petcoke generally refers to a carbonaceous solid produced in oil refinery coker units or other cracking processes. Heavy hydrocarbons generally comprise hydrocarbons which are solid or extremely viscous at standard processing conditions, and can include materials such as, but not limited to, asphaltenes, tars, paraffin waxes, coke, refining residues, and other similar residual hydrocarbon materials. Heavy hydrocarbons can include any material that comprises a majority of hydrocarbon materials with a molecular weight range of about 700 to 2,000,000 Daltons. Heavy oil generally refers to heavy crude, oils sands bitumen, bottom of the barrel and residue left over from refinery processes (e.g., visbreaker bottoms), and any other lower quality material that contains a substantial quantity of high boiling hydrocarbon fractions (e.g., that boil at or above 343 °C, or alternatively at or above about 524 °C). Nonlimiting examples of heavy oil feedstocks include, but are not limited to, Lloydminster heavy oil, Cold Lake bitumen, Athabasca bitumen, atmospheric tower bottoms, vacuum tower bottoms, residuum (or "resid"), resid pitch, vacuum residue, and nonvolatile liquid fractions that remain after subjecting crude oil, bitumen from tar sands, liquefied coal, oil shale, or coal tar feedstocks to distillation, hot separation, and the like; and that contain higher boiling fractions and/or asphaltenes. Naptha generally comprises flammable liquid hydrocarbon mixtures.

[0026] In an aspect, the process for producing ethylene as disclosed herein can comprise separating a natural gas stream into CH ₄ (e.g., a methane stream, such as stream 10, stream 15) and C ₂ H ₆ (e.g., an ethane stream, such as ethane stream 14); wherein the natural gas stream can comprise natural gas, shale gas, associated gas, well head gas, enriched gas, and the like, or combinations thereof. Ethane can be recovered from the natural gas stream by using any suitable methodology, for example by distillation, wherein a deethanizer distillation column is employed.

[0027] The combustion zone 110 can comprise a burner, such as an in-line burner; a furnace; or combinations thereof; wherein the fuel gas stream 10 is burned (e.g., combusted) with the oxidant gas 11 to produce the combustion product. The oxidant gas 1 1 can comprise oxygen, purified oxygen, air, oxygen-enriched air, and the like, or combinations thereof. In some aspects, the oxidant gas is oxygen-enriched, such as oxygen-enriched air, to minimize NO _x production in the combustion zone 1 10. As will be appreciated by one of skill in the art, and with the help of this disclosure, NO _x products can be acidic and as such would necessitate downstream removal. Water or steam can be further introduced to the combustion zone 1 10 to lower and thereby control a combustion product temperature. Combustion products generally comprise combustion products produced according to reactions (1) and (2), such as carbon monoxide (CO), carbon dioxide (C0 ₂ ), water (H ₂ 0), as well as some unconverted hydrocarbons (e.g., hydrocarbons that were present in the fuel gas stream and did not combust), such as unconverted methane. The combustion reactions (1) and (2) occurring in the combustion zone 110 can provide for a combustion temperature of equal to or greater than about 2,000 °C, which combustion temperature can be about the same as the first temperature in the first reaction zone 120. Depending on the configuration of the combustion zone 1 10 and of the first reaction zone 120, the combustion product may not be isolatable, and it might be introduced as produced to the first reaction zone 120.

[0028] In an aspect, the process for producing ethylene as disclosed herein can comprise introducing a first reactant mixture comprising hydrocarbons (e.g., hydrocarbon stream 15) and at least a portion of the combustion product to the first reaction zone 120 to produce a pyrolysis reaction product via a pyrolysis reaction (e.g., reaction (3)), wherein the combustion product heats the hydrocarbons to a first temperature effective for the pyrolysis reaction. As will be appreciated by one of skill in the art, and with the help of this disclosure, a reactant mixture (e.g., first reactant mixture, second reactant mixture) may comprise one or more reactive components (e.g., one or more hydrocarbons, such as CH ₄ ; C ₂ H ₆ ; 0 ₂ ; C0 ₂ ; hydrogen (H ₂ ); etc.) and one or more inert components (e.g., a diluent, such as nitrogen, water, etc.), and the one or more reactive components of the reactant mixture may react in order to form one or more reaction products (e.g., acetylene (C ₂ H ₂ ), CO, etc.). The pyrolysis reaction product comprises unconverted hydrocarbons (e.g., unconverted methane), C ₂ H ₂ , CO, H ₂ , C0 ₂ , and optionally ethylene (C ₂ H ₄ ). The pyrolysis reaction product further comprises H ₂ 0.

[0029] The first reaction zone 120 excludes a catalyst. As will be appreciated by one of skill in the art, and with the help of this disclosure, while there are catalytic processes for hydrocarbon pyrolysis (e.g., methane pyrolysis), the current disclosure does not utilize a catalyst for hydrocarbon pyrolysis; the hydrocarbon pyrolysis as disclosed herein is thermal in contrast to catalyzed.

[0030] In some aspects, a reactor (e.g., a first reactor) can contain both the combustion zone 110 and the first reaction zone 120. In other aspects, a furnace can contain the combustion zone 110; and a reactor (e.g., a first reactor) can contain the first reaction zone 120 and can be configured to receive the combustion product from the furnace comprising the combustion zone 110. A diluent such as an inert gas (e.g., nitrogen, argon, helium, etc.) and/or steam can be further introduced to the first reaction zone 120. [0031] The hydrocarbon stream 15 can be further pre-heated in pre-heaters (e.g., electrical heaters, heat exchangers, etc.) before being heated to the first temperature (e.g., temperature effective for the pyrolysis reaction) by direct heat exchange through contact with the combustion product. A temperature of the combustion product can be a temperature effective to reach a pyrolysis reaction temperature (e.g., first temperature, first reaction zone temperature) of equal to or greater than about 2,000 °C, alternatively equal to or greater than about 2,250 °C, alternatively equal to or greater than about 2,500 °C, alternatively from about 2,000 °C to about 4,000 °C, alternatively from about 2,500 °C to about 4,000 °C, or alternatively about 2,500 °C. As will be appreciated by one of skill in the art, and with the help of this disclosure, higher temperatures in the first reaction zone 120 favor alkyne (e.g., acetylene) formation, while lower temperatures in the first reaction zone 120 favor olefin or alkene (e.g., ethylene) formation.

[0032] In an aspect, the first reaction zone 120 can be characterized by a residence time effective to allow for the conversion of at least a portion of the first reactant mixture to acetylene, for example according to reaction (3). The first reaction zone 120 can be characterized by a residence time of from about 0.1 milliseconds (ms) to 100 ms, alternatively from about 0.5 ms to about 80 ms, or alternatively from about 1 ms to about 50 ms.

[0033] Suppression or reduction of reactions leading to products other than the desired products (e.g., alkynes, acetylene) may be required to achieve the desired products. This may be accomplished by adjusting the reaction temperature, pressure, and/or quenching after a desired residence time. In some aspects, the hydrocarbon stream 15 that is introduced to the first reaction zone 120 can be characterized by a pressure of from about 1 bar to about 20 bar (e.g., from about 100 kPa to about 2,000 kPa), to achieve the desired products.

[0034] The combustion zone 1 10 and/or the first reaction zone 120 can be designed to accommodate one or more gas feed streams (e.g., fuel gas stream 10, hydrocarbon stream 15), which may employ natural gas combined with other gas components including, but not limited to hydrogen, carbon monoxide, carbon dioxide, ethane, and ethylene. The combustion zone 1 10 can be designed to accommodate one or more oxidant gas streams (e.g., oxidant gas 11), such as an oxygen stream and an oxygen-containing stream, for example an air stream, which employ unequal oxidant concentrations for purposes of temperature or composition control. As will be appreciated by one of skill in the art, and with the help of this disclosure, the combustion zone 1 10 and the first reaction zone 120 may comprise a single device or multiple devices. Each device of the combustion zone 1 10 and the first reaction zone 120 may comprise one or more sections. Products from the combustion zone 1 10 are communicated to the first reaction zone 120 via the combustion product stream. Depending on the type and configuration of the combustion zone 110 and the first reaction zone 120 used, the combustion product stream may not be isolatable (for example, in configurations where the combustion zone 1 10 and the first reaction zone 120 are contained within a common vessel or reactor, such as a first reactor).

[0035] In an aspect, the process for producing ethylene as disclosed herein can comprise cooling at least a portion of the pyrolysis reaction product in the quench zone 130 to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature, and wherein the second temperature is lower than the first temperature. The cooled pyrolysis reaction product can comprise unconverted hydrocarbons (e.g., unconverted methane), C2H2, CO, H ₂ , C0 ₂ , H ₂ 0, and optionally C ₂ H ₄ . As will be appreciated by one of skill in the art, and with the help of this disclosure, cooling the pyrolysis reaction product is necessary for subsequent process steps, such as water removal, separation and recovery of carbon dioxide (e.g., a carbon dioxide stream to be recycled to the second reaction zone), liquid phase hydrogenation of acetylene, etc.; as such process steps cannot take place at temperatures in excess of 2,000 °C. Without wishing to be limited by theory, although the reactions taking place in the second reaction zone 140 are endothermic, cooling the pyrolysis reaction product is necessary for the endothermic reactions (4) and (5) that take place in the second reaction zone 140, as temperatures in excess of 2,000 °C could be too high to obtain the desired reaction products with the desired conversions and selectivities.

[0036] In an aspect, at least a portion of the pyrolysis reaction product can be cooled from the first temperature of equal to or greater than about 2,000 °C to a second temperature effective for endothermic reactions of C ₂ H ₆ dehydrogenation and C0 ₂ hydrogenation to produce a cooled pyrolysis reaction product, wherein the second temperature can be from about 700 °C to about 1,000 °C.

[0037] In an aspect, the second temperature can be from about 700 °C to about 1 ,000 °C, alternatively from about 800 °C to about 1,000 °C, or alternatively from about 850 °C to about 950 °C.

[0038] In some aspects, to stop pyrolysis reactions occurring in the first reaction zone 120, prevent undesired reverse reactions, or prevent further reactions that form carbon and hydrocarbon compounds other than the desired products, rapid cooling or "quenching" of pyrolysis reaction products can be employed. In an aspect, the pyrolysis reaction product is quenched in the quench zone 130 prior to exiting the quench zone 130 as the cooled pyrolysis reaction product. The quench zone 130 can employ any suitable quenching methods, for example introducing a quenching fluid (e.g., quenching fluid 13) to the quenching zone 130 (e.g., spraying the quenching fluid; heat exchanging (direct and/or indirect) with the quenching fluid), wherein the quenching fluid can comprise steam, water, hydrocarbons, oil, or liquid product; conveying the product stream (e.g., pyrolysis reaction product) through or into water, natural gas feed, or liquid products; exchanging heat between the product stream (e.g., pyrolysis reaction product) and other streams, such as fuel gas stream 10 and/or hydrocarbon stream 15, thus preheating these other streams and cooling the product stream to a temperature effective for quenching; generating steam, for example by introducing water to the quench zone 130, and recovering steam from the quench zone 130; volume expanding the product stream (e.g., pyrolysis reaction product), which can encompass quenching by converting thermal energy into kinetic energy of the expanding gas (e.g., product stream), such as for example in a Joule Thomson expander (wherein gases cool upon volume expansion via a Joule Thomson effect), in a choke nozzle (which can allow for expanding a gas, wherein the expanding gas can be cooled via a Joule Thomson effect and/or heat exchange with a cooling fluid), in a turbo-expander (wherein work or energy is extracted from an expanding pressurized gas, for example by powering a turbine, resulting in a lower temperature of the expanded gas), etc.; or combinations thereof. In aspects where the quenching fluid 13 comprises water, at least a portion of the quenching fluid 13 can be converted to steam 13a in the quench zone 130. As will be appreciated by one of skill in the art, and with the help of this disclosure, the quench zone 130 may be incorporated within a pyrolysis reactor (e.g., a first reactor), may comprise a separate vessel or device from the pyrolysis reactor, or both. Pyrolysis units for the production of acetylene and ethylene from hydrocarbons are described in more detail in U.S. Patent Nos. 5,824,834; 5,789,644; and 8,445,739; and U.S. Patent Application No. 2010/0167134 Al ; each of which is incorporated by reference herein in its entirety.

[0039] In an aspect, a first reactor can comprise the first reaction zone 120. In some aspects, the first reactor can further comprise the combustion zone 1 10, the quench zone 130, or both the combustion zone 110 and the quench zone 130. In other aspects, the first reactor can comprise the first reaction zone 120 and optionally the combustion zone 110, but not the quench zone 130. In aspects where the first reactor does not comprise the quench zone 130, a second vessel or reactor can comprise the quench zone 130.

[0040] In an aspect, the process for producing ethylene as disclosed herein can comprise introducing a second reactant mixture comprising C ₂ H ₆ (e.g., ethane stream 14) and at least a portion of the cooled pyrolysis reaction product to the second reaction zone 140 to produce a second product mixture 20, wherein at least a portion of C ₂ H ₆ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ (reaction (5)), wherein at least a portion of the C0 ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO (reaction (4)), wherein the second product mixture comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , and unconverted hydrocarbons (e.g., unconverted methane, unconverted ethane), wherein an amount of C ₂ H ₄ in the second product mixture 20 is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, wherein the second product mixture is characterized by a third temperature, and wherein the third temperature is lower than the second temperature.

[0041] In an aspect, the second reaction zone 140 excludes a catalyst. As will be appreciated by one of skill in the art, and with the help of this disclosure, while there are catalytic processes (e.g., with manganese and chromium based catalysts) for C ₂ H ₆ dehydrogenation to C ₂ H ₄ (reaction (5)), as well as C0 ₂ hydrogenation to CO (reaction (4)), the current disclosure does not utilize a catalyst for the conversion of ethane to ethylene and/or carbon dioxide to carbon monoxide in the second reaction zone 140; the conversion of ethane to ethylene and/or carbon dioxide to carbon monoxide as disclosed herein is thermal in contrast to catalyzed.

[0042] In an aspect, the third temperature can be less than about 200 °C, alternatively less than about 100 °C, alternatively from about 20 °C to about 200 °C, alternatively from about 20 °C to about 100 °C, alternatively from about 25 °C to about 50 °C, or alternatively room temperature (e.g, ambient temperature). A reduction in temperature from the second temperature to the third temperature is due to endothermic reactions occurring in the second reaction zone 140, wherein the endothermic reactions comprise the C ₂ H ₆ dehydrogenation reaction to C ₂ H ₆ (reaction (5)) and the hydrogenation reaction of C0 ₂ to CO (reaction (4)). Without wishing to be limited by theory, the reduction in temperature from the second temperature to the third temperature in the second reaction zone 140 is due to quenching of thermal energy (e.g., heat) via endothermic reactions (e.g., reactions (4) and (5)) (e.g., endothermic quench). As will be appreciated by one of skill in the art, and with the help of this disclosure, the quench zone 130 employs a decrease in temperature (e.g., from the first temperature to the second temperature), which results in quenching or stopping the pyrolysis reactions occurring in the first reaction zone 120; and the second reaction zone 140 employs quenching of thermal energy (e.g., endothermic quenching) which further reduces the temperature of the pyrolysis reaction product concurrently with enabling the occurrence of reactions (4) and (5) by providing the necessary energy input via quenched thermal energy.

[0043] In an aspect, at least a portion of ethane of the second reactant mixture can undergo a cracking reaction to produce ethylene in the second reaction zone 140, according to reaction (5). Generally, a cracking reaction refers to a reaction by which a saturated hydrocarbon or mixture of saturated hydrocarbons is broken down into smaller molecules and/or unsaturated molecules. In the case of ethane cracking, C ₂ I¾ is converted to C ₂ H ₄ and H ₂ according to reaction (5). Ethane cracking can provide for an increased amount of H ₂ in the second reaction zone 140, which in turn can provide for at least a portion of the H ₂ necessary to hydrogenate C0 ₂ in the second reaction zone 140, which overall can lead to a higher amount of syngas (H ₂ and CO) in the second product mixture 20. Cracking can be done in the presence of steam, and in this case it can be referred to as "steam cracking." As will be appreciated by one of skill in the art, and with the help of this disclosure, steam for cracking can be supplied by the second reactant mixture that contains at least a portion of the water from the cooled pyrolysis reaction product. Further, as will be appreciated by one of skill in the art, and with the help of this disclosure, steam for cracking can be supplied by the C0 ₂ hydrogenation reaction (reaction (4)). As will be appreciated by one of skill in the art, and with the help of this disclosure, if water from the cooled pyrolysis reaction product and/or water produced by the C0 ₂ hydrogenation reaction is not sufficient for the needs of the steam cracking, additional steam can be introduced into the second reaction zone 140 as necessary. In an aspect, steam can be optionally introduced to the second reaction zone 140, for example via a dedicated steam feed line to the second reaction zone 140 and/or via addition to an existing feed stream (e.g., ethane and/or C0 ₂ stream) to the second reaction zone 140. In some aspects, at least a portion of the steam stream 13a produced in the quench zone 130 can be used in the second reaction zone 140 as necessary.

[0044] In an aspect, at least a portion of the carbon dioxide of the second reactant mixture can undergo a hydrogenation reaction to carbon monoxide in the second reaction zone 140 according to reaction (4). C0 ₂ hydrogenation can provide for an increased amount of CO in the second reaction zone 140, which overall can lead to a higher amount of syngas (H ₂ and CO) in the second product mixture. The amount of hydrogen present in the second reaction zone 140 will determine the H ₂ /CO molar ratio in the second product mixture, as can be seen from reactions (6) and (7):

3H ₂ + C0 ₂ = CO + 2H ₂ + H ₂ 0 (6) 4H ₂ + C0 ₂ = CO + 3H ₂ + H ₂ 0 (7) Reaction (4) is an equilibrium controlled reaction which depends on the H ₂ /C0 ₂ ratio, as it can be seen from reactions (6) and (7).

[0045] The C ₂ H ₆ dehydrogenation to C ₂ H ₄ (reaction (5)) produces H ₂ , wherein at least a portion of the H ₂ from the C ₂ ¾ dehydrogenation reaction (reaction (5)) can be used for the hydrogenation reaction of C0 ₂ to CO (reaction (4)). An overall reaction for the C ₂ ¾ dehydrogenation to C ₂ H ₄ and the hydrogenation reaction of C0 ₂ to CO can be written as follows, according to reaction (8):

C ₂ H ₆ + C0 ₂ = C ₂ H ₄ + CO + H ₂ 0 (8) As will be appreciated by one of skill in the art, and with the help of this disclosure, reaction (8) does not account for H ₂ , as the H ₂ produced by C ₂ H ₆ dehydrogenation can be consumed by C0 ₂ hydrogenation.

[0046] In an aspect, a portion of C ₂ ¾ of the second reactant mixture and a portion of C ₂ H ₂ of the second reactant mixture can undergo a comproportionation reaction to C ₂ H ₄ , according to reaction (9):

C ₂ H ₆ + C ₂ H ₂ = 2C ₂ H ₄ (9) Generally, a comproportionation reaction, also known as a synproportionation reaction, refers to a chemical reaction wherein two reactants (e.g., C ₂ ¾ and C ₂ H ₂ ), each containing the same element (e.g., carbon (C)) but with a different oxidation number, form a product in which the element involved (e.g., C) reaches the same oxidation number in the final product (e.g., C ₂ H ₄ ). C ₂ H ₆ and C ₂ H ₂ comproportionation to C ₂ H ₄ is described in more detail in U.S. Patent No. 8,013,196, which is incorporated by reference herein in its entirety.

[0047] In an aspect, the second reactant mixture present in the second reaction zone can comprise at least a portion of the cooled pyrolysis reaction product and supplemental C ₂ H ₆ and supplemental C0 ₂ .

[0048] In some aspects, the supplemental C ₂ H ₆ can comprise ethane supplied by ethane stream 14 (e.g., fresh C ₂ H ₆ ), from a source other than C ₂ H ₆ recovered downstream of the second reaction zone 140. In other aspects, the supplemental C ₂ ¾ can comprise C ₂ ¾ recovered downstream of the second reaction zone 140 (e.g., separated from a third reaction zone effluent 40 in the second separation unit 400), such as recovered C ₂ ¾ stream 43, as will be described in more detail later herein. In yet other aspects, the supplemental C ₂ ¾ can comprise both (i) fresh C ₂ ¾ (e.g., ethane stream 14); and C ₂ ¾ recovered downstream of the second reaction zone 140.

[0049] In some aspects, the supplemental CO ₂ can comprise CO ₂ recovered from the second product mixture 20 (e.g., CO ₂ stream 35), as will be described in more detail later herein. In other aspects, the supplemental CO ₂ can comprise CO ₂ (e.g., fresh CO ₂ stream 35a) from a source other than the CO ₂ recovered from the second product mixture 20. In yet other aspects, the supplemental CO ₂ can comprise both (i) CO ₂ recovered from the second product mixture 20 (e.g., CO ₂ stream 35); and (ii) fresh CO ₂ (e.g., fresh CO ₂ stream 35a).

[0050] In some aspects, the supplemental ethane and the supplemental CO ₂ can be introduced to the second reaction zone 140 via a common stream. For example, the CO ₂ stream 35 and the ethane stream 14 can be introduced to the second reaction zone 140 via a common stream. In other aspects, the supplemental ethane and the supplemental C(¾ can be introduced to the second reaction zone 140 via separate (e.g., distinct, different) streams. For example, the CO ₂ stream 35 and the ethane stream 14 can be introduced to the second reaction zone 140 via separate (e.g., distinct, different) streams.

[0051] The second reactant mixture can be characterized by a CO ₂ /C ₂ H6 molar ratio of from about 0.8:1 to about 2.0: 1, alternatively from about 1.0: 1 to about 2.0:1, alternatively from about 1.5:1 to about 2.0: 1, alternatively from about 1.6: 1 to about 1.7:1, or alternatively from about 1.2:1 to about 1.45: 1.

[0052] In an aspect, the supplemental ethane and supplemental CO ₂ can be introduced to the second reaction zone 140 at a CO ₂ /C ₂ H6 molar ratio of from about 0.8: 1 to about 2.0: 1, alternatively from about 1.0:1 to about 2.0: 1, alternatively from about 1.5:1 to about 2.0:1, alternatively from about 1.6: 1 to about 1.7:1, or alternatively from about 1.2: 1 to about 1.45: 1.

[0053] In aspects where the CO ₂ recovered from the second product mixture 20 (e.g., CO ₂ stream 35) is not enough for the amount of CO ₂ necessary to be introduced to the second reaction zone 140 and/or the CO ₂ recovered from the second product mixture 20 (e.g., CO ₂ stream 35) cannot provide for the desired CO ₂ /C ₂ H6 molar ratio (e.g., from about 0.8:1 to about 2.0: 1) in the second reactant mixture, fresh C0 ₂ (e.g., fresh C0 ₂ stream 35a) can be introduced to the second reaction zone 140.

[0054] In aspects where the C ₂ H ₆ recovered downstream of the second reaction zone 140 (e.g., recovered C ₂ H ₆ stream 43) is not enough for the amount of C ₂ H ₆ necessary to be introduced to the second reaction zone 140 and/or the C ₂ H ₆ recovered downstream of the second reaction zone 140 (e.g., recovered C ₂ H ₆ stream 43) cannot provide for the desired C0 ₂ /C ₂ H6 molar ratio (e.g., from about 0.8: 1 to about 2.0: 1) in the second reactant mixture, fresh C ₂ H ₆ (e.g., ethane stream 14) can be introduced to the second reaction zone 140.

[0055] In an aspect, an C ₂ H ₆ conversion in the second reaction zone 140 can be equal to or greater than about 65%, alternatively from about 65% to about 80%, or alternatively from about 70% to about 75%. For purposes of the disclosure herein, the conversion of a reagent is a % conversion based on moles converted. For example, the ethane conversion in the second reaction zone 140 can be calculated by using the following equation:

wherein ( _Μ = number of moles of C from C ₂ H ₆ that entered the second reaction zone 140, both from ethane stream 14 and/or recovered C ₂ H ₆ stream 43, and from the cooled pyrolysis reaction product; and wherein _υ ⁼ number of moles of C from C ₂ H ₆ that was recovered

^L 2 ^H 6

from the second reaction zone 140 (e.g., via the second product mixture 20).

[0056] In an aspect, a C0 ₂ conversion in the second reaction zone 140 can be equal to or greater than about 55%, alternatively from about 55% to about 75%, or alternatively from about 60% to about 65%. The C0 ₂ conversion can be calculated by using the following equation:

100%

wherein ( in

co ₂ number of moles of C from C0 ₂ that entered the second reaction zone both from the cooled pyrolysis reaction product, and from recycled C0 ₂ (e.g., recycled C0 ₂ stream

35) and/or fresh C0 ₂ (e.g., fresh C0 ₂ stream 35a); and wherein ( out

co ₂ number of moles of C from C0 ₂ that was recovered from the second reaction zone 140 (e.g., via the second product mixture 20).

[0057] In some aspects, a common reactor can comprise both the first reaction zone 120 and the second reaction zone 140. The common reactor that comprises both the first reaction zone 120 and the second reaction zone 140 can further comprise the quench zone 130 and optionally the combustion zone 1 10. The common reactor can be an autothermal reactor.

[0058] In other aspects, the first reactor can comprise the first reaction zone 120, and a second reactor can comprise the second reaction zone 140. In such aspects, the second reactor can further comprise the quench zone 130. The first reactor and/or second reactor can be autothermal reactors.

[0059] In an aspect, the process for producing ethylene as disclosed herein can comprise separating in the first separation unit 200 at least a portion of the second product mixture 20 into an ethylene and acetylene stream 30 and a carbon dioxide stream 35, wherein the ethylene and acetylene stream 30 comprises C ₂ H ₄ , C ₂ H ₂ , CO, H ₂ , and unconverted hydrocarbons (e.g., unconverted methane, unconverted ethane).

[0060] In some aspects, at least a portion of the second product mixture 20 can be further compressed (e.g., via a compressor) to produce a compressed second product mixture, followed by optionally feeding at least a portion of the compressed second product mixture to a water removal unit, prior to introducing at least a portion of the second product mixture 20 to the first separation unit 200. Generally, compressing a gas mixture that contains water to increase its pressure will lead to the water condensing at the increased pressure at an increased temperature as compared to a temperature where water of an otherwise similar gas mixture condenses at pressure lower than the increased pressure. The compressed second product mixture can be further introduced to a water removal unit (e.g., a water quench vessel and/or a cooling tower), where the compressed second product mixture can be further cooled to promote water condensation and removal.

[0061] In some aspects, least a portion of C0 ₂ can be separated from the second product mixture 20 to yield the C0 ₂ stream 35 by using a C0 ₂ separator. The C0 ₂ separator can comprise C0 ₂ removal by amine (e.g., monoethanolamine) absorption, (e.g., amine scrubbing), pressure swing adsorption, temperature swing adsorption, gas separation membranes (e.g., porous inorganic membranes, palladium membranes, polymeric membranes, zeolites, etc.), and the like, or combinations thereof. In an aspect, the C0 ₂ separator can comprise C0 ₂ removal by amine absorption.

[0062] In an aspect, at least a portion of the C0 ₂ stream 35 can be recycled to the second reaction zone 140. In some aspects, the C0 ₂ stream 35 (e.g., recycled C0 ₂ stream 35) can be further contacted with additional carbon dioxide (e.g., fresh C0 ₂ stream 35a) prior to introducing to the second reaction zone 140.

[0063] In some aspects, the separation unit 200 can employ distillation and/or cryogenic distillation to produce the ethylene and acetylene stream 30.

[0064] In an aspect, the process for producing ethylene as disclosed herein can comprise (i) introducing at least a portion of the ethylene and acetylene stream 30 and a polar aprotic solvent to the third reaction zone 300 (e.g., a liquid phase hydrogenation reactor), wherein the third reaction zone 300 comprises an acetylene hydrogenation catalyst; and (ii) allowing at least a portion of the C ₂ H ₂ in the ethylene and acetylene stream 30 to undergo hydrogenation to C ₂ H ₄ to produce a third reaction zone effluent 40, wherein the third reaction zone effluent 40 comprises C ₂ H ₄ , CO, H ₂ , and unconverted hydrocarbons (e.g., unconverted methane, unconverted ethane), and wherein an amount of C ₂ H ₄ in the third reaction zone effluent 40 is greater than an amount of C ₂ H ₄ in the ethylene and acetylene stream 30. At least a portion of the H ₂ in the ethylene and acetylene stream 30 hydrogenates at least a portion of the C ₂ H ₂ of the ethylene and acetylene stream 30 to produce C ₂ H ₄ .

[0065] Nonlimiting examples of polar aprotic solvents suitable for use in the present disclosure include N-methyl-2-pyrrolidone (NMP), Ν,Ν-dimethylformamide (DMF), acetone, tetrahydrofuran (THF), dimethylsulfoxide (DMSO), and the like, or combinations thereof.

[0066] The third reaction zone 300 can comprise any suitable liquid phase hydrogenation reactor, such as a fixed bed catalytic reactor (typically operated adiabatically); and/or a tubular reactor (typically operated isothermally). Generally, the liquid phase hydrogenation reactor comprises an acetylene hydrogenation catalyst, such as a palladium (Pd) based catalyst, which can be supported on alumina, zeolites, etc. The acetylene hydrogenation catalyst can further comprise other metals, such as platinum, silver, nickel, etc. In an aspect, the acetylene hydrogenation catalyst can comprise PCI/AI ₂ O ₃ . Liquid phase hydrogenation of acetylene processes are described in more detail in U.S. Patent No. 4,128,595, which is incorporated by reference herein in its entirety.

[0067] In an aspect, the process for producing ethylene as disclosed herein can comprise separating in the second separation unit 400 at least a portion of the third reaction zone effluent 40 into an ethylene stream 42, a syngas stream 41, and an unconverted hydrocarbons stream; wherein the syngas stream 41 comprises H ₂ and CO; and wherein the unconverted hydrocarbons stream comprises unconverted methane and unconverted ethane. The syngas stream 41 can be characterized by a H ₂ /CO molar ratio of from about 1 : 1 to about 2: 1 , alternatively from about 1.1 : 1 to about 1.95:1, or alternatively from about 1.2: 1 to about 1.9: 1. In some aspects, the second separation unit 400 can employ distillation and/or cryogenic distillation to produce the ethylene stream 42, the syngas stream 41, and the unconverted hydrocarbons stream.

[0068] In an aspect, the process for producing ethylene as disclosed herein can further comprise separating at least a portion of the unconverted hydrocarbons stream into a recovered ethane stream 43 (e.g., unconverted ethane stream) and an unconverted methane stream, for example via distillation and/or cryogenic distillation. In an aspect, at least a portion 43 a of the recovered ethane stream 43 can be recycled to the second reaction zone 140, for example via ethane stream 14. In an aspect, at least a portion of the unconverted methane stream can be recycled to the combustion zone 1 10 and/or the first reaction zone 120, for example via stream 10 and/or stream 15, respectively.

[0069] In an aspect, at least a portion of the ethylene stream 42 can be polymerized to produce a polymer product, such as polyethylene, an ethylene copolymer, ethylene oligomers, etc.

[0070] In an aspect, at least a portion of the syngas stream 41 can be further used for methanol production, olefin synthesis, hydrocarbonylation reactions, and the like, or combinations thereof.

[0071] In some aspects, at least a portion of the syngas stream 41 can be introduced to a fourth reaction zone (e.g., methanol production unit) comprising a methanol production catalyst to produce a methanol stream. The methanol production unit can comprise any reactor suitable for a methanol synthesis reaction from CO and H ₂ , such as for example an isothermal reactor, an adiabatic reactor, a slurry reactor, a cooled multi tubular reactor, and the like, or combinations thereof. Nonlimiting examples of methanol production catalysts suitable for use in the methanol production unit in the current disclosure include Cu, Cu/ZnO, Cu/Th0 ₂ , Cu/Zn/Al ₂ 03, Cu/ZnO/Al ₂ 03, Cu/Zr, and the like, or combinations thereof.

[0072] In an aspect, a process for producing ethylene as disclosed herein can comprise (a) introducing a fuel gas stream and an oxidant gas to a combustion zone to produce a combustion product; (b) introducing a first reactant mixture comprising hydrocarbons (e.g., methane) and at least a portion of the combustion product to a first reaction zone to produce a pyrolysis reaction product via a pyrolysis reaction, wherein the combustion product heats the hydrocarbons to a first temperature of equal to or greater than about 2,500 °C, wherein the first reaction zone excludes a catalyst, and wherein the pyrolysis reaction product comprises unconverted hydrocarbons (e.g., unconverted methane), C ₂ H ₂ , CO, H ₂ , C0 ₂ , and optionally C ₂ H ₄ ; (c) cooling at least a portion of the pyrolysis reaction product in a quench zone to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature of from about 800 °C to about 1,000 °C; (d) introducing a second reactant mixture comprising C ₂ H ₆ and at least a portion of the cooled pyrolysis reaction product to a second reaction zone to produce a second product mixture, wherein the second reaction zone excludes a catalyst, wherein the second reactant mixture is characterized by a C0 ₂ /C ₂ H6 molar ratio of from about 0.8: 1 to about 2: 1, wherein at least a portion of C ₂ H ₆ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ , wherein at least a portion of the C0 ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO, wherein the second product mixture comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , and unconverted hydrocarbons (e.g., unconverted methane, unconverted ethane), wherein an amount of C ₂ H ₄ in the second product mixture is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, and wherein the second product mixture is characterized by a third temperature of less than about 200 °C; (e) separating at least a portion of the second product mixture into an ethylene and acetylene stream and a carbon dioxide stream, wherein the ethylene and acetylene stream comprises C ₂ H ₄ , C ₂ H ₂ , CO, H ₂ , and unconverted hydrocarbons (e.g., unconverted methane, unconverted ethane); (f) recycling at least a portion of the carbon dioxide stream to the second reaction zone; (g) introducing at least a portion of the ethylene and acetylene stream and a polar aprotic solvent to a third reaction zone to produce a third reaction zone effluent via hydrogenation to C ₂ H ₄ of at least a portion of the C ₂ H ₂ in the ethylene and acetylene stream, wherein the third reaction zone comprises an acetylene hydrogenation catalyst, wherein the third reaction zone effluent comprises C ₂ H ₄ , CO, H ₂ , and unconverted hydrocarbons (e.g., unconverted methane, unconverted ethane), and wherein an amount of C ₂ H ₄ in the third reaction zone effluent is greater than an amount of C ₂ H ₄ in the ethylene and acetylene stream; (h) separating at least a portion of the third reaction zone effluent into an ethylene stream, a syngas stream, an unconverted methane stream, and an unconverted ethane stream, wherein the syngas stream comprises H ₂ and CO; (i) introducing at least a portion of the syngas stream to a fourth reaction zone comprising a methanol production catalyst to produce a methanol stream; (j) recycling at least a portion of the unconverted methane stream to the first reaction zone and/or the combustion zone; and (k) recycling at least a portion of the unconverted ethane stream to the second reaction zone. In such an aspect, a C0 ₂ conversion in the second reaction zone can be equal to or greater than about 55%, and a C ₂ H ₆ conversion in the second reaction zone can be equal to or greater than about 65%.

[0073] In an aspect, a process for producing ethylene as disclosed herein can comprise (a) combusting methane (CH ₄ ) and oxygen (0 ₂ ) to produce a combustion product at a first temperature of equal to or greater than about 2,500 °C; (b) pyrolyzing CH ₄ in the presence of at least a portion of the combustion product in a first reaction zone at the first temperature of equal to or greater than about 2,500 °C to produce a pyrolysis reaction product, wherein the pyrolysis reaction product comprises unconverted methane, C ₂ H ₂ , CO, H ₂ , C0 ₂ , and optionally C ₂ H ₄ ; (c) cooling at least a portion of the pyrolysis reaction product from the first temperature of equal to or greater than about 2,500 °C to a second temperature effective for endothermic reactions of C ₂ H ₆ dehydrogenation and C0 ₂ hydrogenation to produce a cooled pyrolysis reaction product, wherein the second temperature is from about 800 °C to about 1,000 °C, and wherein the cooled pyrolysis reaction product comprises unconverted methane, C ₂ H ₂ , CO, H ₂ , C0 ₂ , and optionally C ₂ H ₄ ; (d) at a temperature of from about 800 °C to about 1,000 °C in a common reaction zone (e.g., second reaction zone), concurrently (i) dehydrogenating ethane (C ₂ H ₆ ) to produce C ₂ H ₄ and H ₂ ; (ii) hydrogenating at least a portion of C0 ₂ present in the cooled pyrolysis reaction product to produce CO; and (iii) comproportionating C ₂ H ₆ and at least a portion of the C ₂ H ₂ present in the cooled pyrolysis reaction product to produce C ₂ H ₄ ; wherein (i), (ii), and (iii) yield a combined reaction product, and wherein the combined reaction product comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , unconverted methane, and unconverted ethane; (e) separating C ₂ H ₄ from the combined reaction product; (f) hydrogenating at least a portion of the C ₂ H ₂ of the combined reaction product to produce C ₂ H ₄ ; wherein hydrogenating occurs in liquid phase in the presence of a polar aprotic solvent; (g) separating syngas from the combined reaction product, wherein the syngas comprises CO and H ₂ ; and (h) converting at least a portion of the syngas to methanol.

[0074] In an aspect, a process for producing ethylene as disclosed herein can advantageously display improvements in one or more process characteristics when compared to an otherwise similar process that does not integrate hydrocarbon pyrolysis with other processes for producing desired products, such as carbon dioxide hydrogenation and ethane dehydrogenation. Thermal conversion of methane to acetylene, with subsequent thermal conversion of carbon dioxide to CO, as well as ethane dehydrogenation to ethylene advantageously improve the overall process efficiency for the conversion of natural gas to ethylene. The ethane dehydrogenation to ethylene and the carbon dioxide hydrogenation can advantageously use a portion of the combustion heat generated during pyrolysis, and can advantageously cool a pyrolysis product (e.g., cooled pyrolysis reaction product), such that the pyrolysis product can be further subjected to separation processes that enable the recovery of ethylene.

[0075] A synthesis gas (e.g., H ₂ and CO) to methanol conversion process as disclosed herein can increase further the overall efficiency of the process by producing methanol from the H ₂ and CO obtained from hydrocarbon pyrolysis, as well as C0 ₂ hydrogenation. The methanol can be advantageously used as a liquid fuel, and can be easily transported, as compared to transporting gases. Additional advantages of the process for producing ethylene as disclosed herein can be apparent to one of skill in the art viewing this disclosure.

EXAMPLES

[0076] The subject matter having been generally described, the following examples are given as particular embodiments of the disclosure and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification of the claims to follow in any manner.

EXAMPLE 1

[0077] The combustion and pyrolysis of methane was investigated at high temperature in a pyrolysis unit, and the products after pyrolysis were quenched to room temperature. The combustion and pyrolysis was conducted via three steps: (i) the combustion of fuel gases in a combustion chamber; (ii) mixing of cracking feed (e.g., methane separated from natural gas/field gas/shale gas) with the products of combustion in a mixing section; followed by (iii) the cracking or pyrolysis of the above mixture from step (ii) in a reactor section. The combustion chamber produced hot gases with a temperature of about 2,500 °C. The hot gases produced in the combustion chamber were mixed with the cracking feed (e.g., natural gas feed) which was optionally preheated to 300-500 °C. The combustion gases transferred heat to the cracking feed by direct contact and the feed underwent pyrolysis. Major products from pyrolysis included acetylene (C ₂ H ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ), and hydrogen (¾). However ethylene (C ₂ H ₄ ), and water (mostly from the combustion chamber) were also formed. The products were quenched by water spray to <300 °C.

[0078] A sample from the quenched products was injected into a gas chromatograph (GC), which analyzed the composition of the quenched products. The results of the GC runs are displayed in Table 1.

Table 1

[0079] The data in Table 1 provides a typical composition of various gas streams produced in the methane combustion and pyrolysis as disclosed herein. As can be seen from data in Table 1 , a C ₂ yield of about 34% was achieved. The achieved C ₂ yield is high by comparison with the maximum C ₂ yield (less than 24%, as outlined in J. Chem. Soc, Chem. Commun., 1992, p. 1546, which is incorporated by reference herein in its entirety) that can be obtained via catalytic oxidative methane coupling.

[0080] Carbon dioxide was separated from the pyrolysis products; was mixed with ethane (e.g., separated from natural gas/field gas/shale gas); and was introduced to the pyrolysis unit in a quench zone, wherein the pyrolysis products were cooled both by water quench and by endothermic reactions of carbon dioxide hydrogenation and ethane dehydrogenation to ethylene. Conversion of ethane in the quench zone was about 75%, and the carbon dioxide conversion in the quench zone was about 60%.

[0081] For the purpose of any U.S. national stage filing from this application, all publications and patents mentioned in this disclosure are incorporated herein by reference in their entireties, for the purpose of describing and disclosing the constructs and methodologies described in those publications, which might be used in connection with the methods of this disclosure. Any publications and patents discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention.

[0082] In any application before the United States Patent and Trademark Office, the Abstract of this application is provided for the purpose of satisfying the requirements of 37 C.F.R. § 1.72 and the purpose stated in 37 C.F.R. § 1.72(b) "to enable the United States Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure." Therefore, the Abstract of this application is not intended to be used to construe the scope of the claims or to limit the scope of the subject matter that is disclosed herein. Moreover, any headings that can be employed herein are also not intended to be used to construe the scope of the claims or to limit the scope of the subject matter that is disclosed herein. Any use of the past tense to describe an example otherwise indicated as constructive or prophetic is not intended to reflect that the constructive or prophetic example has actually been carried out.

[0083] The present disclosure is further illustrated by the following examples, which are not to be construed in any way as imposing limitations upon the scope thereof. On the contrary, it is to be clearly understood that resort can be had to various other aspects, embodiments, modifications, and equivalents thereof which, after reading the description herein, can be suggest to one of ordinary skill in the art without departing from the spirit of the present invention or the scope of the appended claims.

ADDITIONAL DISCLOSURE

[0084] A first aspect, which is a process for producing ethylene comprising (a) introducing a fuel gas stream and an oxidant gas to a combustion zone to produce a combustion product; (b) introducing a first reactant mixture comprising hydrocarbons and at least a portion of the combustion product to a first reaction zone to produce a pyrolysis reaction product via a pyrolysis reaction, wherein the combustion product heats the hydrocarbons to a first temperature effective for the pyrolysis reaction, and wherein the pyrolysis reaction product comprises unconverted hydrocarbons, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (¾), carbon dioxide (C0 ₂ ), and optionally ethylene (C ₂ H ₄ ); (c) cooling at least a portion of the pyrolysis reaction product in a quench zone to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature, and wherein the second temperature is lower than the first temperature; (d) introducing a second reactant mixture comprising ethane (C ₂ H ₆ ) and at least a portion of the cooled pyrolysis reaction product to a second reaction zone to produce a second product mixture, wherein the second reaction zone excludes a catalyst, wherein at least a portion of C ₂ H ₆ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ , wherein at least a portion of the C0 ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO, wherein the second product mixture comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , and unconverted hydrocarbons, wherein an amount of C ₂ H ₄ in the second product mixture is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, wherein the second product mixture is characterized by a third temperature, and wherein the third temperature is lower than the second temperature; (e) separating at least a portion of the second product mixture into an ethylene and acetylene stream and a carbon dioxide stream, wherein the ethylene and acetylene stream comprises C ₂ H ₄ , C ₂ H ₂ , CO, H ₂ , and unconverted hydrocarbons; and (f) recycling at least a portion of the carbon dioxide stream to the second reaction zone.

[0085] A second aspect, which is the process of the first aspect, wherein the first reaction zone further excludes a catalyst.

[0086] A third aspect, which is the process of any one of the first and the second aspects, wherein a common reactor comprises both the first reaction zone and the second reaction zone.

[0087] A fourth aspect, which is the process of the third aspect, wherein the common reactor further comprises the quench zone and the combustion zone.

[0088] A fifth aspect, which is the process of any one of the first and the second aspects, wherein a first reactor comprises the first reaction zone, and wherein a second reactor comprises the second reaction zone. [0089] A sixth aspect, which is the process of the fifth aspect, wherein the first reactor further comprises the combustion zone.

[0090] A seventh aspect, which is the process of any one of the fifth and the sixth aspects, wherein the second reactor further comprises the quench zone.

[0091] An eighth aspect, which is the process of any one of the first through the seventh aspects, wherein the recycled carbon dioxide stream is further contacted with additional carbon dioxide during step (f).

[0092] A ninth aspect, which is the process of any one of the first through the eighth aspects, wherein the recycled carbon dioxide stream and the C ₂ ¾ are introduced to the second reaction zone via a common stream.

[0093] A tenth aspect, which is the process of any one of the first through the ninth aspects, wherein the carbon dioxide stream is separated from the second product mixture by amine absorption.

[0094] An eleventh aspect, which is the process of any one of the first through the tenth aspects, wherein the C ₂ H ₆ dehydrogenation reaction further produces H ₂ , and wherein at least a portion of the H ₂ from the C ₂ H ₆ dehydrogenation reaction is used for the hydrogenation reaction of C0 ₂ to CO.

[0095] A twelfth aspect, which is the process of any one of the first through the eleventh aspects, wherein a portion of C ₂ H ₆ of the second reactant mixture and a portion of C ₂ H ₂ of the second reactant mixture undergo a comproportionation reaction to C ₂ H ₄ .

[0096] A thirteenth aspect, which is the process of any one of the first through the twelfth aspects further comprising (i) introducing at least a portion of the ethylene and acetylene stream and a polar aprotic solvent to a third reaction zone, wherein the third reaction zone comprises an acetylene hydrogenation catalyst; (ii) allowing at least a portion of the C ₂ H ₂ in the ethylene and acetylene stream to undergo hydrogenation to C ₂ H ₄ to produce a third reaction zone effluent, wherein the third reaction zone effluent comprises C ₂ H ₄ , CO, H ₂ , and unconverted hydrocarbons, and wherein an amount of C ₂ H ₄ in the third reaction zone effluent is greater than an amount of C ₂ H ₄ in the ethylene and acetylene stream; and (iii) separating at least a portion of the third reaction zone effluent into an ethylene stream, a syngas stream, and an unconverted hydrocarbons stream, wherein the syngas stream comprises H ₂ and CO. [0097] A fourteenth aspect, which is the process of the thirteenth aspect, wherein the step (iii) of separating at least a portion of the third reaction zone effluent further comprises separating a recovered ethane stream from the unconverted hydrocarbons stream.

[0098] A fifteenth aspect, which is the process of the fourteenth aspect, wherein at least a portion of the recovered ethane stream is recycled to the second reaction zone as the C ₂ H ₆ .

[0099] A sixteenth aspect, which is the process of any one of the first through the fifteenth aspects, wherein the polar aprotic solvent comprises N-methyl-2-pyrrolidone (NMP), N,N- dimethylformamide (DMF), acetone, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), or combinations thereof.

[00100] A seventeenth aspect, which is the process of any one of the first through the sixteenth aspects, wherein the acetylene hydrogenation catalyst comprises palladium (Pd).

[00101] An eighteenth aspect, which is the process of any one of the first through the seventeenth aspects, wherein the syngas stream is characterized by a H ₂ /CO molar ratio of from about 1 : 1 to about 2: 1.

[00102] A nineteenth aspect, which is the process of any one of the first through the eighteenth aspects further comprising introducing at least a portion of the syngas stream to a fourth reaction zone comprising a methanol production catalyst to produce a methanol stream.

[00103] A twentieth aspect, which is the process of the nineteenth aspect, wherein the methanol production catalyst comprises Cu, Cu/ZnO, Cu/Th0 ₂ , Cu/Zn/Al ₂ 0 ₃ , Cu/ZnO/Al ₂ 0 ₃ , Cu/Zr, or combinations thereof.

[00104] A twenty-first aspect, which is the process of any one of the first through the twentieth aspects, wherein at least a portion of the C ₂ H ₆ of the second reaction mixture is separated from natural gas, shale gas, associated gas, well head gas, enriched gas, or combinations thereof.

[00105] A twenty-second aspect, which is the process of any one of the first through the twenty-first aspects, wherein the first temperature is equal to or greater than about 2,000 °C.

[00106] A twenty-third aspect, which is the process of any one of the first through the twenty- second aspects, wherein the second temperature is from about 700 °C to about 1,000 °C.

[00107] A twenty-fourth aspect, which is the process of any one of the first through the twenty-third aspects, wherein the third temperature is from about 20 °C to about 200 °C. [00108] A twenty-fifth aspect, which is the process of any one of the first through the twenty- fourth aspects, wherein a reduction in temperature from the second temperature to the third temperature is due to endothermic reactions occurring in the second reaction zone, wherein the endothermic reactions comprise the C ₂ H ₆ dehydrogenation reaction and the hydrogenation reaction of C0 ₂ to CO.

[00109] A twenty-sixth aspect, which is the process of any one of the first through the twenty- fifth aspects, wherein the step (c) of cooling at least a portion of the pyrolysis reaction product in a quench zone further comprises introducing a quenching fluid to the quench zone, wherein the quenching fluid comprises water, hydrocarbons, oil, or combinations thereof.

[00110] A twenty-seventh aspect, which is the process of the twenty-sixth aspect, wherein the quenching fluid comprises water, and wherein at least a portion of the quenching fluid is converted to steam during step (c).

[00111] A twenty-eighth aspect, which is the process of any one of the first through the twenty-seventh aspects, wherein the second reactant mixture is characterized by a C0 ₂ to C ₂ H ₆ molar ratio of from about 0.8: 1 to about 2: 1.

[00112] A twenty-ninth aspect, which is the process of any one of the first through the twenty- eighth aspects, wherein a C0 ₂ conversion in the second reaction zone is equal to or greater than about 55%.

[00113] A thirtieth aspect, which is the process of any one of the first through the twenty- ninth aspects, wherein a C ₂ H ₆ conversion in the second reaction zone is equal to or greater than about 65%.

[00114] A thirty-first aspect, which is the process of any one of the first through the thirtieth aspects, wherein a portion of the fuel gas stream is fed to the first reaction zone to provide the hydrocarbons thereto.

[00115] A thirty-second aspect, which is the process of any one of the first through the thirty- first aspects, wherein the fuel gas stream and/or the hydrocarbons comprise methane, ethane, propane, natural gas, natural gas liquids, associated gas, well head gas, enriched gas, heavy hydrocarbons, petcoke, naphtha, heavy oil, heavy oil residue, or combinations thereof.

[00116] A thirty-third aspect, which is the process of any one of the first through the thirty- second aspects, wherein the oxidant gas comprises oxygen, purified oxygen, air, oxygen- enriched air, or combinations thereof. [00117] A thirty-fourth aspect, which is a process for producing ethylene and methanol comprising (a) introducing a fuel gas stream and an oxidant gas to a combustion zone to produce a combustion product; (b) separating a natural gas stream into methane (CH ₄ ) and ethane (C ₂ ¾); (c) introducing a first reactant mixture comprising at least a portion of the CH ₄ and at least a portion of the combustion product to a first reaction zone to produce a pyrolysis reaction product via a pyrolysis reaction, wherein the combustion product heats the CH ₄ to a first temperature of equal to or greater than about 2,500 °C, wherein the first reaction zone excludes a catalyst, and wherein the pyrolysis reaction product comprises unconverted methane, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (¾), carbon dioxide (CO ₂ ), and optionally ethylene (C ₂ H ₄ ); (d) cooling at least a portion of the pyrolysis reaction product in a quench zone to produce a cooled pyrolysis reaction product, wherein the cooled pyrolysis reaction product is characterized by a second temperature of from about 800 °C to about 1,000 °C; (e) introducing a second reactant mixture comprising at least a portion of the C ₂ ¾ and at least a portion of the cooled pyrolysis reaction product to a second reaction zone to produce a second product mixture, wherein the second reaction zone excludes a catalyst, wherein at least a portion of C ₂ ¾ of the second reactant mixture undergoes a dehydrogenation reaction to produce C ₂ H ₄ , wherein at least a portion of the CO ₂ of the second reactant mixture undergoes a hydrogenation reaction to CO, wherein the second product mixture comprises C ₂ H ₄ , CO, ¾, C ₂ H ₂ , CO ₂ , unconverted methane, and unconverted ethane, wherein an amount of C ₂ H ₄ in the second product mixture is greater than an amount of C ₂ H ₄ in the pyrolysis reaction product, and wherein the second product mixture is characterized by a third temperature of less than about 200 °C; (f) separating at least a portion of the second product mixture into an ethylene and acetylene stream and a carbon dioxide stream, wherein the ethylene and acetylene stream comprises C ₂ H ₄ , C ₂ H ₂ , CO, ¾, unconverted methane, and unconverted ethane; (g) recycling at least a portion of the carbon dioxide stream to the second reaction zone; (h) introducing at least a portion of the ethylene and acetylene stream and a polar aprotic solvent to a third reaction zone to produce a third reaction zone effluent via hydrogenation to C ₂ H ₄ of at least a portion of the C ₂ H ₂ in the ethylene and acetylene stream, wherein the third reaction zone comprises an acetylene hydrogenation catalyst, wherein the third reaction zone effluent comprises C ₂ H ₄ , CO, ¾, unconverted methane, and unconverted ethane, and wherein an amount of C ₂ H ₄ in the third reaction zone effluent is greater than an amount of C ₂ H ₄ in the ethylene and acetylene stream; (i) separating at least a portion of the third reaction zone effluent into an ethylene stream, a syngas stream, an unconverted methane stream, and an unconverted ethane stream, wherein the syngas stream comprises H ₂ and CO; and (j) introducing at least a portion of the syngas stream to a fourth reaction zone comprising a methanol production catalyst to produce a methanol stream.

[00118] A thirty-fifth aspect, which is the process of the thirty-fourth aspect, wherein at least a portion of the unconverted methane stream is recycled to the step (c) as the CH ₄ .

[00119] A thirty-sixth aspect, which is the process of any one of the thirty-fourth and the thirty-fifth aspects, wherein at least a portion of the unconverted ethane stream is recycled to the step (e) as the C ₂ H ₆ .

[00120] A thirty-seventh aspect, which is the process of any one of the thirty-fourth through the thirty-sixth aspects, wherein the second reactant mixture is characterized by a C0 ₂ to C ₂ H ₆ molar ratio of from about 0.8: 1 to about 2: 1.

[00121] A thirty-eighth aspect, which is a process for producing ethylene comprising (a) combusting methane (CH ₄ ) and oxygen (0 ₂ ) to produce a combustion product at a first temperature of equal to or greater than about 2,500 °C; (b) pyrolyzing CH ₄ in the presence of at least a portion of the combustion product in a first reaction zone at the first temperature of equal to or greater than about 2,500 °C to produce a pyrolysis reaction product, wherein the pyrolysis reaction product comprises unconverted methane, acetylene (C ₂ H ₂ ), carbon monoxide (CO), hydrogen (H ₂ ), carbon dioxide (C0 ₂ ), and optionally ethylene (C ₂ H ₄ ); (c) cooling at least a portion of the pyrolysis reaction product from the first temperature of equal to or greater than about 2,500 °C to a second temperature effective for endothermic reactions of C ₂ H ₆ dehydrogenation and C0 ₂ hydrogenation to produce a cooled pyrolysis reaction product, wherein the second temperature is from about 800 °C to about 1,000 °C, and wherein the cooled pyrolysis reaction product comprises unconverted methane, C ₂ H ₂ , CO, H ₂ , C0 ₂ , and optionally C ₂ H ₄ ; (d) at a temperature of from about 800 °C to about 1,000 °C, concurrently (i) dehydrogenating ethane (C ₂ H ₆ ) to produce C ₂ H ₄ and H ₂ ; (ii) hydrogenating at least a portion of C0 ₂ present in the cooled pyrolysis reaction product to produce CO; and (iii) comproportionating C ₂ H ₆ and at least a portion of the C ₂ H ₂ present in the cooled pyrolysis reaction product to produce C ₂ H ₄ ; wherein (i), (ii), and (iii) yield a combined reaction product, and wherein the combined reaction product comprises C ₂ H ₄ , CO, H ₂ , C ₂ H ₂ , C0 ₂ , unconverted methane, and unconverted ethane; and (e) separating C ₂ H ₄ from the combined reaction product. [00122] A thirty-ninth aspect, which is the process of the thirty-eighth aspect further comprising hydrogenating at least a portion of the C ₂ H ₂ of the combined reaction product to produce C ₂ H ₄ ; wherein hydrogenating occurs in liquid phase in the presence of a polar aprotic solvent.

[00123] A fortieth aspect, which is the process of any one of the thirty-eighth and the thirty- ninth aspects further comprising separating syngas from the combined reaction product, wherein the syngas comprises CO and H ₂ .

[00124] A forty-first aspect, which is the process of the fortieth aspect further comprising converting at least a portion of the syngas to methanol.

[00125] While embodiments of the disclosure have been shown and described, modifications thereof can be made without departing from the spirit and teachings of the invention. The embodiments and examples described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention.

[00126] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an embodiment of the present invention. Thus, the claims are a further description and are an addition to the detailed description of the present invention. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference.