CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/796,255, filed January 24, 2019, which is hereby incorporated by reference in its entirety.

FIELD OF INVENTION

[0002] The present disclosure is directed processes for conversion of synthesis gas into methanol.

BACKGROUND OF THE INVENTION

[0003] Synthesis gas, commonly referred to as syngas, can be converted into methanol. The effluent from a methanol synthesis reactor can be subjected to one or more separation processes to recover various compounds therein. An ongoing need exists for efficient processes for the production of methanol, including the separation of one or more compounds from the effluent from a methanol synthesis reactor.

SUMMARY OF THE INVENTION

[0004] Disclosed herein is a process for producing methanol comprising (a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream, wherein the syngas comprises hydrogen (¾), carbon monoxide (CO), and carbon dioxide (CO2), wherein the methanol reactor is characterized by a methanol reactor pressure, wherein the methanol reactor is characterized by a methanol reactor temperature, and wherein the methanol reactor effluent stream comprises methanol, water, ¾, CO, CO2, and wax compounds, (b) separating at least a portion of the methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream, wherein the first separating unit is characterized by a first separating unit temperature, wherein the liquid stream comprises methanol, water, and wax compounds, and wherein the first vapor stream comprises ¾, CO, CO2, methanol, and water, (c) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream, wherein the second separating unit is characterized by a second separating unit temperature, wherein the wax stream comprises at least a portion of the wax compounds of the liquid stream, and wherein the second vapor stream comprises methanol and water, (d) separating at least a portion of the first vapor stream in a third separating unit into a crude methanol stream and a third vapor stream, wherein the third separating unit is characterized by a third separating unit temperature, wherein the crude methanol stream comprises methanol and water, and wherein the third vapor stream comprises ¾, CO, and CO2, and (e) recovering at least a portion of the methanol from the crude methanol stream and/or the second vapor stream.

[0005] Also disclosed herein is a process for producing methanol comprising (a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream, wherein the syngas comprises hydrogen (¾), carbon monoxide (CO), and carbon dioxide (CO2), wherein the methanol reactor is characterized by a methanol reactor pressure, wherein the methanol reactor is characterized by a methanol reactor temperature, and wherein the methanol reactor effluent stream comprises methanol, water, ¾, CO, CO2, and wax compounds, (b) cooling at least a portion of the methanol reactor effluent stream in a first heat exchanger to yield a cooled methanol reactor effluent stream, (c) separating at least a portion of the cooled methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream, wherein the first separating unit is characterized by a first separating unit temperature, wherein the liquid stream comprises methanol, water, and wax compounds, and wherein the first vapor stream comprises ¾, CO, CO2, methanol, and water, (d) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream, wherein the second separating unit is characterized by a second separating unit temperature, wherein the wax stream comprises at least a portion of the wax compounds of the liquid stream, and wherein the second vapor stream comprises methanol and water, (e) cooling at least a portion of the first vapor stream in a second heat exchanger to yield a cooled first vapor stream, (f) separating at least a portion of the cooled first vapor stream in a third separating unit into a cmde methanol stream and a third vapor stream, wherein the third separating unit is characterized by a third separating unit temperature, wherein the crude methanol stream comprises methanol and water, and wherein the third vapor stream comprises ¾, CO, and CO2, (g) contacting at least a portion of the crude methanol stream and at least a portion of the second vapor stream to form a combined crude methanol stream, (h) separating at least a portion of the combined crude methanol stream in a distillation unit into a methanol stream and a water stream, wherein the distillation unit comprises one or more distillation columns, (i) recycling equal to or greater than about 80 wt.% of the third vapor stream, based on the total weight of the third vapor stream, to the methanol reactor, and (j) optionally heating at least a portion of the syngas in the first heat exchanger and/or the second heat exchanger to yield heated syngas, wherein at least a portion of the heated syngas is fed to the methanol reactor in step (a).

[0006] In the context of the present invention at least twenty embodiments are described. Embodiment 1 relates to a process for producing methanol. The process includes the steps of (a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream; wherein the syngas contains hydrogen (¾), carbon monoxide (CO), and carbon dioxide (CO2); wherein the methanol reactor is characterized by a methanol reactor pressure; wherein the methanol reactor is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream contains methanol, water, ¾, CO, CO2, and wax compounds; (b) separating at least a portion of the methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream; wherein the first separating unit is characterized by a first separating unit temperature; wherein the liquid stream contains methanol, water, and wax compounds; and wherein the first vapor stream contains ¾, CO, CO2, methanol, and water; (c) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream; wherein the second separating unit is characterized by a second separating unit temperature; wherein the wax stream contains at least a portion of the wax compounds of the liquid stream; and wherein the second vapor stream contains methanol and water; (d) separating at least a portion of the first vapor stream in a third separating unit into a cmde methanol stream and a third vapor stream; wherein the third separating unit is characterized by a third separating unit temperature; wherein the cmde methanol stream contains methanol and water; and wherein the third vapor stream contains ¾, CO, and CO2; and (e) recovering at least a portion of the methanol from the cmde methanol stream and/or the second vapor stream. Embodiment 2 is the process of embodiment 1, wherein a first portion of the third vapor stream is recycled to the methanol reactor; and wherein a second portion of the third vapor stream is purged and/or used as fuel. Embodiment 3 is the process of embodiment 2, wherein the first portion of the third vapor stream is from about 50 wt.% to about 100 wt.%; and wherein the second portion of the third vapor stream is from about 0 wt.% to about 50 wt.%. Embodiment 4 is the process of any of embodiments 1 to 3, further comprising (i) cooling at least a portion of the methanol reactor effluent stream in a first heat exchanger to yield a cooled methanol reactor effluent stream, wherein at least a portion of the cooled methanol reactor effluent stream is introduced to the first separating unit in step (b); and/or (ii) cooling at least a portion of the first vapor stream in a second heat exchanger to yield a cooled first vapor stream, wherein at least a portion of the cooled first vapor stream is introduced to the third separating unit in step (d). Embodiment 5 is the process of embodiment 4 further comprising heating at least a portion of the syngas in the first heat exchanger and/or the second heat exchanger to yield heated syngas, wherein at least a portion of the heated syngas is fed to the methanol reactor in step (a). Embodiment 6 is the process of any of embodiments 1 to 5, wherein the first separating unit and/or the third separating unit operate at a pressure that is about the same as the methanol reactor pressure. Embodiment 7 is the process of any of embodiments 1 to 6, wherein the methanol reactor pressure is from about 40 barg to about 100 barg. Embodiment 8 is the process of any of embodiments 1 to 7, wherein the second separating unit operates at a second separating unit pressure, and wherein the second separating unit pressure is lower than the methanol reactor pressure. Embodiment 9 is the process of embodiment 8, wherein the second separating unit pressure is less than about 30 barg. Embodiment 10 is the process of any of embodiments 1 to 9, wherein the methanol reactor temperature is greater than the first separating unit temperature; wherein the first separating unit temperature is equal to or greater than the second separating unit temperature; and wherein the third separating unit temperature is less than first separating unit temperature and/or the second separating unit temperature. Embodiment 11 is the process of any of embodiments 1 to 10, wherein the methanol reactor temperature is from about 170 °C to about 250 °C. Embodiment 12 is the process of any of embodiments 1 to 11, wherein the first separating unit temperature is from about 100 °C to about 180 °C. Embodiment 13 is the process of any of embodiments 1 to 12, wherein the second separating unit temperature is from about 80 °C to about 160 °C. Embodiment 14 is the process of any of embodiments 1 to 13, wherein the third separating unit temperature is from about 20 °C to about 75 °C. Embodiment 15 is the process of any of embodiments 1 to 14, wherein the wax compounds contains C20 ₊ compounds, C20 ₊ hydrocarbons, C20 ₊ alcohols, C20 ₊ ethers, or combinations thereof. Embodiment 16 is the process of any of embodiments 1 to 15, further including the step of (1) contacting at least a portion of the crude methanol stream and at least a portion of the second vapor stream to form a combined crude methanol stream; and (2) separating at least a portion of the combined crude methanol stream in a distillation unit into a methanol stream and a water stream, wherein the distillation unit includes one or more distillation columns.

[0007] Embodiment 17 is a process for producing methanol. The process includes the steps of (a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream; wherein the syngas contains hydrogen (¾), carbon monoxide (CO), and carbon dioxide (CO2); wherein the methanol reactor is characterized by a methanol reactor pressure; wherein the methanol reactor is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream contains methanol, water, ¾, CO, CO2, and wax compounds; (b) cooling at least a portion of the methanol reactor effluent stream in a first heat exchanger to yield a cooled methanol reactor effluent stream; (c) separating at least a portion of the cooled methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream; wherein the first separating unit is characterized by a first separating unit temperature; wherein the liquid stream contains methanol, water, and wax compounds; and wherein the first vapor stream contains ¾, CO, CO2, methanol, and water; (d) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream; wherein the second separating unit is characterized by a second separating unit temperature; wherein the wax stream contains at least a portion of the wax compounds of the liquid stream; and wherein the second vapor stream contains methanol and water; (e) cooling at least a portion of the first vapor stream in a second heat exchanger to yield a cooled first vapor stream; (f) separating at least a portion of the cooled first vapor stream in a third separating unit into a crude methanol stream and a third vapor stream; wherein the third separating unit is characterized by a third separating unit temperature; wherein the crude methanol stream contains methanol and water; and wherein the third vapor stream contains ¾, CO, and CO2; (g) contacting at least a portion of the crude methanol stream and at least a portion of the second vapor stream to form a combined crude methanol stream; (h) separating at least a portion of the combined crude methanol stream in a distillation unit into a methanol stream and a water stream, wherein the distillation unit includes one or more distillation columns; (i) recycling equal to or greater than about 80 wt.% of the third vapor stream, based on the total weight of the third vapor stream, to the methanol reactor; and (j) optionally heating at least a portion of the syngas in the first heat exchanger and/or the second heat exchanger to yield heated syngas, wherein at least a portion of the heated syngas is fed to the methanol reactor in step (a). Embodiment 18 is the process of embodiment 17, wherein the methanol reactor pressure is from about 80 barg to about 100 barg; wherein the first separating unit and/or the third separating unit operate at a pressure that is about the same as the methanol reactor pressure; and wherein the second separating unit operates at a second separating unit pressure of less than about 20 barg. Embodiment 19 is the process of embodiment 18, wherein at least a portion of the wax stream is in liquid phase at the second separating unit temperature and at the second separating unit pressure. Embodiment 20 is the process of any of embodiments 17-19, wherein the methanol reactor temperature is from about 190 °C to about 230 °C; wherein the first separating unit temperature is from about 120 °C to about 160 °C; wherein the second separating unit temperature is from about 100 °C to about 140 °C; wherein the first separating unit temperature is equal to or greater than the second separating unit temperature; and wherein the third separating unit temperature is from about 25 °C to about 65 °C.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a detailed description of the preferred aspects of the disclosed methods, reference will now be made to the accompanying drawing in which:

[0009] Figure 1 is a process flow diagram of a methanol production process 100 in accordance with the present disclosure.

[0010] Figure 2 is a process flow diagram of a methanol production process 200 in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Disclosed herein is a process for producing methanol comprising (a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream; wherein the syngas comprises hydrogen (¾), carbon monoxide (CO), and carbon dioxide (CO2); wherein the methanol reactor is characterized by a methanol reactor pressure; wherein the methanol reactor is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream comprises methanol, water, ¾, CO, CO2, and wax compounds; (b) separating at least a portion of the methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream; wherein the first separating unit is characterized by a first separating unit temperature; wherein the liquid stream comprises methanol, water, and wax compounds; and wherein the first vapor stream comprises ¾, CO, CO2, methanol, and water; (c) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream; wherein the second separating unit is characterized by a second separating unit temperature; wherein the wax stream comprises at least a portion of the wax compounds of the liquid stream; and wherein the second vapor stream comprises methanol and water; (d) separating at least a portion of the first vapor stream in a third separating unit into a crude methanol stream and a third vapor stream; wherein the third separating unit is characterized by a third separating unit temperature; wherein the crude methanol stream comprises methanol and water; and wherein the third vapor stream comprises ¾, CO, and CO2; and (e) recovering at least a portion of the methanol from the crude methanol stream and/or the second vapor stream.

[0012] Further disclosed herein is a process for producing methanol comprising: (a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream; wherein the syngas comprises hydrogen (H2), carbon monoxide (CO), and carbon dioxide (C02); wherein the methanol reactor is characterized by a methanol reactor pressure; wherein the methanol reactor is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream comprises methanol, water, H2, CO, C02, and wax compounds; (b) cooling at least a portion of the methanol reactor effluent stream in a first heat exchanger to yield a cooled methanol reactor effluent stream; (c) separating at least a portion of the cooled methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream; wherein the first separating unit is characterized by a first separating unit temperature; wherein the liquid stream comprises methanol, water, and wax compounds; and wherein the first vapor stream comprises H2, CO, C02, methanol, and water; (d) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream; wherein the second separating unit is characterized by a second separating unit temperature; wherein the wax stream comprises at least a portion of the wax compounds of the liquid stream; and wherein the second vapor stream comprises methanol and water; (e) cooling at least a portion of the first vapor stream in a second heat exchanger to yield a cooled first vapor stream; (f) separating at least a portion of the cooled first vapor stream in a third separating unit into a cmde methanol stream and a third vapor stream; wherein the third separating unit is characterized by a third separating unit temperature; wherein the cmde methanol stream comprises methanol and water; and wherein the third vapor stream comprises H2, CO, and C02; (g) contacting at least a portion of the cmde methanol stream and at least a portion of the second vapor stream to form a combined cmde methanol stream; (h) separating at least a portion of the combined cmde methanol stream in a distillation unit into a methanol stream and a water stream, wherein the distillation unit comprises one or more distillation columns; (i) recycling equal to or greater than about 80 wt.% of the third vapor stream, based on the total weight of the third vapor stream, to the methanol reactor; and (j) optionally heating at least a portion of the syngas in the first heat exchanger and/or the second heat exchanger to yield heated syngas, wherein at least a portion of the heated syngas is fed to the methanol reactor in step (a).

[0013] Figure 1 is a process flow diagram of an embodiment of methanol production process 100. Referring to Figure 1, syngas (i.e., synthesis gas) feed stream 5 comprising hydrogen, carbon monoxide, and carbon dioxide is fed to methanol reactor 10 to produce methanol reactor effluent stream 12 comprising methanol (MeOH), water (FhO), hydrogen (Fh), carbon monoxide (CO), carbon dioxide (CO2), and wax compounds. The syngas stream 5 may also comprise water and methane. The methanol reactor effluent stream 12 is passed through a first heat exchanger 15, wherein stream 12 is cooled to yield a cooled methanol reactor effluent stream 17. First heat exchanger 15 can be any suitable equipment that is configured to enable indirect heat exchange with one or more process streams such as syngas feed stream 5, whereby syngas feed stream 5 is preheated (and methanol reactor effluent stream 12 is cooled) prior to introduction into methanol reactor 10. In an aspect, first heat exchanger 15 is a shell and tube heat exchanger. In an aspect, the methanol reactor 10 can be characterized by a pressure of from about 40 barg to about 100 barg, alternatively of from about 70 barg to about 100 barg, alternatively from about 75 barg to about 95 barg, or alternatively from about 80 barg to about 85 barg. In an aspect, the methanol reactor 10 can be characterized by a temperature of from about 170 °C to about 250 °C. In an aspect, the methanol reactor 10 temperature is greater than the first separating unit temperature.

[0014] The terms“wax compounds” or“wax” as used herein refers to any compound present in the methanol reactor effluent stream that can be a solid at about room temperature (e.g., at about 25 °C) and ambient pressure (e.g., about 14.7 psia). The term“wax compounds” includes compounds (e.g., hydrocarbons comprising carbon and hydrogen and/or higher alcohols) having equal to or greater than about 6 carbon atoms (e.g., C6+ compounds), having equal to or greater than about 7 carbon atoms (e.g., C7+ compounds), having equal to or greater than about 8 carbon atoms (e.g., C8+ compounds), having equal to or greater than about 9 carbon atoms (e.g., C9+ compounds), having equal to or greater than about 10 carbon atoms (e.g., C10+ compounds), having equal to or greater than about 15 carbon atoms (e.g., 05+ compounds), having equal to or greater than about 20 carbon atoms (e.g., C20+ compounds), or combinations thereof. The term“wax compounds” includes hydrocarbon wax, paraffins (e.g., paraffin oil, paraffin wax), and higher alcohols (e.g., C6+ alcohols). Hydrocarbon wax includes long chain alkanes, cycloalkanes (e.g., naphthenes), and combinations thereof, for example compounds represented by the formula C„H2 _/i+ 2, where n ranges from about 10 to about 100, alternatively from about 20 to about 80, alternatively from about 20 to about 50, alternatively from about 20 to about 40. Paraffin oil includes a mixture of hydrocarbon compounds having from about 10 carbon atoms (CIO) to about 20 carbon atoms (C20). Paraffin wax includes a mixture of hydrocarbon compounds having from about 20 carbon atoms (C20) to about 40 carbon atoms (C40) and a melting point in a range of from about 37 °C to about 68 °C, alternatively in a range of from about 46 °C to about 68 °C. In an aspect, the wax compounds comprise C20+ compounds, for example C20+ hydrocarbons, C20+ alcohols, C20+ ethers, or combinations thereof. In an aspect, the wax compounds are gaseous upon exiting the methanol reactor (e.g., in methanol reactor effluent stream 12), and may become solid as the effluent stream temperature lowers downstream from the methanol reactor.

[0015] The methanol reactor 10 can comprise any reactor suitable for a methanol synthesis reaction from CO and ¾ and optionally CO2, such as for example an isothermal reactor, an adiabatic reactor, a trickle bed reactor, a fluidized bed reactor, a slurry reactor, a loop reactor, a cooled multi tubular reactor, and the like, or combinations thereof.

[0016] Generally, CO and ¾ can be converted into methanol (CH3OH), for example as represented by equation (1):

CO + H ₂ CH3OH (1)

CO2 and ¾ can also be converted to methanol, for example as represented by equation (2):

C0 ₂ + 3H ₂ CH3OH + H2O (2)

[0017] Methanol synthesis from CO, CO2 and ¾ is a catalytic process, and is most often conducted in the presence of copper based catalysts. The methanol reactor can comprise a methanol production catalyst, such as any suitable commercial catalyst used for methanol synthesis. Nonlimiting examples of methanol production catalysts suitable for use in the methanol reactor in the current disclosure include Cu, Cu/ZnO, Cu/Th02, Cu/Zn/A1203, Cu/Zn0/A1203, Cu/Zr, and the like, or combinations thereof.

[0018] Syngas stream 5 can be produced conventionally by steam reforming of natural gas (steam methane reforming or SMR), although other hydrocarbon sources can be used for syngas production, such as refinery off-gases, naphtha feedstocks, heavy hydrocarbons, coal, biomass, etc. SMR is an endothermic process and requires significant energy input to drive the reaction forward. Conventional endothermic technologies such as SMR produce syngas with a hydrogen content greater than the required content for methanol synthesis. Generally, SMR produces syngas with an M ratio ranging from 2.6 to 2.98, wherein the M ratio is a molar ratio defined as (H2-C0 ₂ )/(C0+C0 ₂ ).

[0019] In an autothermal reforming (ATR) process, a portion of the natural gas is burned as fuel to drive the conversion of natural gas to syngas resulting in relatively low hydrogen and high CO2 concentrations. Conventional methanol production plants utilize a combined reforming (CR) technology that pairs SMR with autothermal reforming (ATR) to reduce the amount of hydrogen present in syngas. ATR produces a syngas with a hydrogen content lower than the required content for methanol synthesis. Generally, ATR produces syngas with an M ratio ranging from 1.7 to 1.84. In the CR technology, the natural gas feed volumetric flowrate to the SMR and the ATR can be adjusted to achieve an overall syngas M ratio of 2.0 to 2.06. Further, CR syngas has a hydrogen content greater than the required content for methanol synthesis. Furthermore, SMR is a highly endothermic process, and the endothermicity of the SMR technology requires burning fuel to drive the syngas synthesis. Consequently, the SMR technology reduces the energy efficiency of the methanol synthesis process.

[0020] Syngas can also be produced by catalytic partial oxidation (CPO or CPOx) of natural gas. CPO processes employ partial oxidation of hydrocarbon feeds to syngas comprising CO and ¾. The CPO process is exothermic, thus eliminating the need for external heat supply. The composition of the produced syngas may not be suitable for methanol synthesis, for example, owing to a reduced hydrogen content. However, the hydrogen content of syngas produced by CPO can be optimized for the product of methanol, for example as described in detail in U.S. Pat. App. No. 62/787,574 filed January 2, 2019 and entitled “Hydrogen Enrichment in Syngas Produced via Catalytic Partial Oxidation” and U.S. Pat. App. No. 62/787,598 filed January 2, 2019 and entitled“Methanol Production Process”, each of which is incorporated by reference in its entirety. In an aspect, syngas feed stream 5 is produced via a CPO process and has a hydrogen to carbon monoxide (H2/CO) molar ratio of greater than about 2.0; an M ratio of equal to or greater than about 1.7, where M ratio is a molar ratio defined as (H2-C02)/(C0+C02); or both.

[0021] In an aspect, the syngas feed stream 5 can be compressed, e.g., in a single compression stage, prior to introducing at least a portion thereof to the methanol reactor 10.

[0022] Referring to Figure 1, cooled methanol reactor effluent stream 17 is fed to a first separating unit 20 to produce a first vapor stream 22 comprising gaseous phase ¾, CO, CO2, H2O, and methanol and a liquid stream 24 comprising liquid phase methanol, H2O, and wax compounds. First separating unit 20 can be any suitable equipment that is configured to separate the components of the cooled methanol reactor effluent stream 17 (e.g., MeOH, H2O, ¾, CO, CO2, and wax compounds) into the first vapor stream 22 comprising gaseous phase ¾, CO, CO2, H2O and the liquid stream 24 comprising liquid phase methanol, H2O, and wax compounds. In an aspect, the first separating unit 20 comprises a gas-liquid separator, such as a vapor-liquid separator, flash drum, knock-out drum, knock-out pot, compressor suction drum, etc. In an aspect, first separating unit 20 is a vapor-liquid separator, for example a flash drum, having an operating temperature in a range of from about 100 °C to about 180 °C and an operating pressure of from about 70 barg to about 100 barg. In an aspect, the first separating unit 20 operates at a first separating unit pressure that is about the same as the methanol reactor 10 pressure. In an aspect, the first separating unit temperature is equal to or greater than the second separating unit temperature. [0023] Liquid stream 24 is fed to a second separating unit 25 to produce a second vapor stream 27 comprising gaseous phase H2O and methanol and wax stream 29 comprising liquid phase wax compounds. Second separating unit 25 can be any suitable equipment that is configured to separate the components of the liquid stream 24 (e.g., MeOH, H2O, and wax compounds) into the second vapor stream 27 comprising gaseous phase H2O and methanol and the wax stream 29 comprising liquid phase wax compounds. In an aspect, the second separating unit 25 comprises a gas-liquid separator, such as a vapor-liquid separator, flash drum, knock-out drum, knock-out pot, compressor suction drum, etc. In an aspect, second separating unit 25 is a vapor-liquid separator, for example a flash drum, having an operating temperature in a range of from about 80 °C to about 160 °C and an operating pressure of less than about 30 barg, alternatively from less than about 30 barg to about 0 barg. In an aspect, the second separating unit operates at a second separating unit pressure, and wherein the second separating unit pressure is lower than the methanol reactor 10 pressure.

[0024] First vapor stream 22 is passed through a second heat exchanger 30, wherein stream 22 is cooled to yield a cooled first vapor stream 32. Second heat exchanger 30 can be any suitable equipment that is configured to enable indirect heat exchange with one or more process streams such as syngas feed stream 5, whereby syngas feed stream 5 is preheated (and first vapor stream 22 is cooled) prior to introduction into methanol reactor 10. In an aspect, second heat exchanger 30 is a shell and tube heat exchanger.

[0025] The cooled first vapor stream 32 is fed to a third separating unit 35 to produce a third vapor stream 37 comprising gaseous phase ¾, CO, and CO2 and a crude methanol stream 24 comprising liquid phase methanol and H2O. Third separating unit 35 can be any suitable equipment that is configured to separate the components of the cooled first vapor stream 32 (e.g., MeOH, H2O, ¾, CO, CO2) into the third vapor stream 37 comprising gaseous phase ¾, CO, CO2 and the crude methanol stream 39 comprising liquid phase methanol and H2O. In an aspect, the third separating unit 35 comprises a gas-liquid separator, such as a vapor-liquid separator, flash drum, knock-out drum, knock-out pot, compressor suction drum, etc. In an aspect, third separating unit 35 is a vapor-liquid separator, for example a flash drum, having an operating temperature in a range of from about 20 °C to about 75 °C and an operating pressure of from about 70 barg to about 100 barg. In an aspect, the third separating unit 35 operates at a third separating unit pressure that is about the same as the methanol reactor 10 pressure. In an aspect, the third separating unit temperature is less than first separating unit temperature and/or the second separating unit temperature. [0026] A methanol product stream 42 can be produced by separating methanol from the second vapor stream 27, the crude methanol stream 39, or both. For example, the second vapor stream 27, the crude methanol stream 39, or both can be fed together or separately to distillation unit 40 to produce methanol product stream 42 and water stream 44. As shown in Figure 1, the second vapor stream 27 and combined with the crude methanol stream 39 to form combined methanol stream 41 comprising methanol and water, and combined methanol stream 41 is fed to distillation unit 40 to produce methanol product stream 42 and water stream 44. The distillation unit 40 can be any suitable equipment that is configured to separate the methanol and water, for example one or more distillation columns.

[0027] All or a portion of the third vapor stream 37 comprising Fh, CO, and CO2 can be recycled to the methanol reactor 10. For example, a first portion of third vapor stream 37 is recycled via recycle vapor stream 46 to methanol reactor 10. Third vapor stream 37 can be fed directly to methanol reactor 10, or all or a portion of third vapor stream 37 can be combined with syngas feed stream 5 and the combined stream 47 fed to the methanol reactor 10. Furthermore, all or a portion of the third vapor stream 37 comprising Fh, CO, and CO2 can be purged from the process 100, for example to assist in limiting the buildup of CO2 in the process via recycle vapor stream 46. In an aspect, a first portion of third vapor stream 37 is recycled via recycle vapor stream 46 to methanol reactor 10 and a second portion of third vapor stream 37 is purged from process 100 via a purge vapor stream 49. In an aspect, the first portion of the third vapor stream is from about 50 wt.% to about 100 wt.%, alternatively from about 75 wt.% to about 100 wt.%, alternatively from about 90 wt.% to about 100 wt.%,; and the second portion of the third vapor stream is from about 0 wt.% to about 50 wt.%, alternatively from about 0 wt.% to about 25 wt.%, alternatively from about 0 wt.% to about 10 wt.%. In an aspect, purge vapor stream 49 may be combusted, for example as a fuel gas.

[0028] The process 100 for producing methanol as shown in Figure 1 comprises (a) feeding syngas stream 5 to the methanol reactor 10 to produce a methanol reactor effluent stream 12; wherein the syngas stream 5 comprises hydrogen (Fh), carbon monoxide (CO), and carbon dioxide (CO2); wherein the methanol reactor 10 is characterized by a methanol reactor pressure; wherein the methanol reactor 10 is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream 12 comprises methanol, water, Fh, CO, CO2, and wax compounds; (b) cooling at least a portion of the methanol reactor effluent stream 12 in a first heat exchanger 15 to yield a cooled methanol reactor effluent stream 17; (c) separating at least a portion of the cooled methanol reactor effluent stream 17 in a first separating unit 20 into a liquid stream 24 and a first vapor stream 22; wherein the first separating unit 20 is characterized by a first separating unit temperature; wherein the liquid stream 24 comprises methanol, water, and wax compounds; and wherein the first vapor stream 22 comprises ¾, CO, CO2, methanol, and water; (d) separating at least a portion of the liquid stream 24 in a second separating unit 25 into a wax stream 29 and a second vapor stream 27; wherein the second separating unit 25 is characterized by a second separating unit temperature; wherein the wax stream 28 comprises at least a portion of the wax compounds of the liquid stream 24; and wherein the second vapor stream 27 comprises methanol and water; (e) cooling at least a portion of the first vapor stream 22 in a second heat exchanger 30 to yield a cooled first vapor stream 32; (f) separating at least a portion of the cooled first vapor stream 32 in a third separating unit 35 into a crude methanol stream 39 and a third vapor stream 37; wherein the third separating unit 35 is characterized by a third separating unit temperature; wherein the cmde methanol stream 39 comprises methanol and water; and wherein the third vapor stream 37 comprises ¾, CO, and CO2; (g) contacting at least a portion of the cmde methanol stream 39 and at least a portion of the second vapor stream 27 to form a combined cmde methanol stream 41; (h) separating at least a portion of the combined cmde methanol stream 41 in a distillation unit 40 into a methanol stream 42 and a water stream 44, wherein the distillation unit 40 comprises one or more distillation columns; (i) recycling equal to or greater than about 80 wt.% of the third vapor stream 37, based on the total weight of the third vapor stream 37, to the methanol reactor 10 via recycle vapor stream 46; and (j) optionally heating at least a portion of the syngas stream 5 in the first heat exchanger and/or the second heat exchanger to yield a preheated syngas stream, wherein at least a portion of the preheated syngas stream is fed to the methanol reactor. Within methanol process 100, the methanol reactor pressure can be from about 80 barg to about 100 barg; the first separating unit and/or the third separating unit can operate at a pressure that is about the same as the methanol reactor pressure; the second separating unit can operate at a second separating unit pressure of less than about 20 barg; at least a portion of the wax stream can be in liquid phase at the second separating unit temperature and at the second separating unit pressure; the methanol reactor temperature can be from about 190 °C to about 230 °C; the first separating unit temperature can be from about 120 °C to about 160 °C; the second separating unit temperature can be from about 100 °C to about 140 °C; the first separating unit temperature can be equal to or greater than the second separating unit temperature; and the third separating unit temperature can be from about 25 °C to about 65 °C.

[0029] Figure 2 is a process flow diagram of a methanol production process 200 in accordance with the present disclosure, the pertinent details of which are described by the figure itself. Figure 2 shows an embodiment comprising three flash drums, wherein the first flash drum operates at a temperature and pressure as described herein (e.g., temperature of about 140 °C and pressure of about 91 barg), the second flash drum operates at a temperature and pressure as described herein (e.g„ temperature of about 120 °C and pressure of about 3.5 barg), and the third flash drum operates at a temperature and pressure as described herein.

[0030] The presently disclosed process advantageously removes the wax compounds, and thereby avoids fouling of downstream process equipment upon cooling and solidification of the wax compounds. Accordingly, as the need to clean waxy solids from process equipment is greatly reduced, likewise costly process downtime is greatly reduced.

ADDITIONAL DISCLOSURES

[0031] The following are nonlimiting specific embodiments in accordance with the present disclosure:

[0032] A first aspect which is a process for producing methanol comprising:

(a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream; wherein the syngas comprises hydrogen (Eb), carbon monoxide (CO), and carbon dioxide (CO2); wherein the methanol reactor is characterized by a methanol reactor pressure; wherein the methanol reactor is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream comprises methanol, water, Eb, CO, CO2, and wax compounds;

(b) separating at least a portion of the methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream; wherein the first separating unit is characterized by a first separating unit temperature; wherein the liquid stream comprises methanol, water, and wax compounds; and wherein the first vapor stream comprises Eb, CO, CO2, methanol, and water;

(c) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream; wherein the second separating unit is characterized by a second separating unit temperature; wherein the wax stream comprises at least a portion of the wax compounds of the liquid stream; and wherein the second vapor stream comprises methanol and water;

(d) separating at least a portion of the first vapor stream in a third separating unit into a crude methanol stream and a third vapor stream; wherein the third separating unit is characterized by a third separating unit temperature; wherein the crude methanol stream comprises methanol and water; and wherein the third vapor stream comprises ¾, CO, and CO2; and

(e) recovering at least a portion of the methanol from the crude methanol stream and/or the second vapor stream.

[0033] A second aspect which is the process of the first aspect, wherein a first portion of the third vapor stream is recycled to the methanol reactor; and wherein a second portion of the third vapor stream is purged and/or used as fuel.

[0034] A third aspect which is the process of the second aspect, wherein the first portion of the third vapor stream is from about 50 wt.% to about 100 wt.%; and wherein the second portion of the third vapor stream is from about 0 wt.% to about 50 wt.%.

[0035] A fourth aspect which is the process of any of the first to the third aspects further comprising (i) cooling at least a portion of the methanol reactor effluent stream in a first heat exchanger to yield a cooled methanol reactor effluent stream, wherein at least a portion of the cooled methanol reactor effluent stream is introduced to the first separating unit in step (b); and/or (ii) cooling at least a portion of the first vapor stream in a second heat exchanger to yield a cooled first vapor stream, wherein at least a portion of the cooled first vapor stream is introduced to the third separating unit in step (d).

[0036] A fifth aspect which is the process of the fourth aspect further comprising heating at least a portion of the syngas in the first heat exchanger and/or the second heat exchanger to yield heated syngas, wherein at least a portion of the heated syngas is fed to the methanol reactor in step (a).

[0037] A sixth aspect which is the process of any of the first to the fifth aspects, wherein the first separating unit and/or the third separating unit operate at a pressure that is about the same as the methanol reactor pressure.

[0038] A seventh aspect which is the process of any of the first to the sixth aspects, wherein the methanol reactor pressure is from about 40 barg to about 100 barg.

[0039] An eighth aspect which is the process of any of the first to the seventh aspects, wherein the second separating unit operates at a second separating unit pressure, and wherein the second separating unit pressure is lower than the methanol reactor pressure.

[0040] A ninth aspect which is the process of the eighth aspect, wherein the second separating unit pressure is less than about 30 barg.

[0041] A tenth aspect which is the process of any of the first to the ninth aspects, wherein the methanol reactor temperature is greater than the first separating unit temperature; wherein the first separating unit temperature is equal to or greater than the second separating unit temperature; and wherein the third separating unit temperature is less than first separating unit temperature and/or the second separating unit temperature.

[0042] An eleventh aspect which is the process of any of the first to the tenth aspects, wherein the methanol reactor temperature is from about 170 °C to about 250 °C.

[0043] A twelfth aspect which is the process of any of the first to the eleventh aspects, wherein the first separating unit temperature is from about 100 °C to about 180 °C.

[0044] A thirteenth aspect which is the process of any of the first to the twelfth aspects, wherein the second separating unit temperature is from about 80 °C to about 160 °C.

[0045] A fourteenth aspect which is the process of any of the first to the thirteenth aspects, wherein the third separating unit temperature is from about 20 °C to about 75 °C.

[0046] A fifteenth aspect which is the process of any of the first to the fourteenth aspects, wherein the wax compounds comprise C20 ₊ compounds, C20 ₊ hydrocarbons, C20 ₊ alcohols, C20 ₊ ethers, or combinations thereof.

[0047] A sixteenth aspect which is the process of any of the first to the fifteenth aspects further comprising (1) contacting at least a portion of the crude methanol stream and at least a portion of the second vapor stream to form a combined crude methanol stream; and (2) separating at least a portion of the combined crude methanol stream in a distillation unit into a methanol stream and a water stream, wherein the distillation unit comprises one or more distillation columns.

[0048] A seventeenth aspect which is a process for producing methanol comprising:

(a) feeding syngas to a methanol reactor to produce a methanol reactor effluent stream; wherein the syngas comprises hydrogen (¾), carbon monoxide (CO), and carbon dioxide (CO2); wherein the methanol reactor is characterized by a methanol reactor pressure; wherein the methanol reactor is characterized by a methanol reactor temperature; and wherein the methanol reactor effluent stream comprises methanol, water, ¾, CO, CO2, and wax compounds;

(b) cooling at least a portion of the methanol reactor effluent stream in a first heat exchanger to yield a cooled methanol reactor effluent stream;

(c) separating at least a portion of the cooled methanol reactor effluent stream in a first separating unit into a liquid stream and a first vapor stream; wherein the first separating unit is characterized by a first separating unit temperature; wherein the liquid stream comprises methanol, water, and wax compounds; and wherein the first vapor stream comprises ¾, CO, CO2, methanol, and water; (d) separating at least a portion of the liquid stream in a second separating unit into a wax stream and a second vapor stream; wherein the second separating unit is characterized by a second separating unit temperature; wherein the wax stream comprises at least a portion of the wax compounds of the liquid stream; and wherein the second vapor stream comprises methanol and water;

(e) cooling at least a portion of the first vapor stream in a second heat exchanger to yield a cooled first vapor stream;

(f) separating at least a portion of the cooled first vapor stream in a third separating unit into a crude methanol stream and a third vapor stream; wherein the third separating unit is characterized by a third separating unit temperature; wherein the crude methanol stream comprises methanol and water; and wherein the third vapor stream comprises ¾, CO, and CO2;

(g) contacting at least a portion of the crude methanol stream and at least a portion of the second vapor stream to form a combined crude methanol stream;

(h) separating at least a portion of the combined crude methanol stream in a distillation unit into a methanol stream and a water stream, wherein the distillation unit comprises one or more distillation columns;

(i) recycling equal to or greater than about 80 wt.% of the third vapor stream, based on the total weight of the third vapor stream, to the methanol reactor; and

(j) optionally heating at least a portion of the syngas in the first heat exchanger and/or the second heat exchanger to yield heated syngas, wherein at least a portion of the heated syngas is fed to the methanol reactor in step (a).

[0049] An eighteenth aspect which is the process of the seventeenth aspect, wherein the methanol reactor pressure is from about 80 barg to about 100 barg; wherein the first separating unit and/or the third separating unit operate at a pressure that is about the same as the methanol reactor pressure; and wherein the second separating unit operates at a second separating unit pressure of less than about 20 barg.

[0050] A nineteenth aspect which is the process of claim 18, wherein at least a portion of the wax stream is in liquid phase at the second separating unit temperature and at the second separating unit pressure.

[0051] A twentieth aspect which is the process of any of the seventeenth to the nineteenth aspects, wherein the methanol reactor temperature is from about 190 °C to about 230 °C; wherein the first separating unit temperature is from about 120 °C to about 160 °C; wherein the second separating unit temperature is from about 100 °C to about 140 °C; wherein the first separating unit temperature is equal to or greater than the second separating unit temperature; and wherein the third separating unit temperature is from about 25 °C to about 65 °C.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.