VARANASI NAGA SANYASI RAO (IN)
DITTRICH CHRISTOPH JOHANNES (NL)
| WO2014173791A1 | 2014-10-30 |
| GB709035A | 1954-05-12 | |||
| US6239057B1 | 2001-05-29 |
| CLAIMS What is claimed is: 1. A method of Ci to C4 hydrocarbon dehydroaromatization, comprising: passing a first stream comprising a first portion of Ci to C4 hydrocarbons and an oxidant comprising oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section; combining the second stream with a second portion of the Ci to C4 hydrocarbons to form a third stream; passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed; and removing the fourth stream from the dehydroaromatization catalyst bed; wherein the third stream has a temperature of 400°C to l,000°C. 2. The method of Claim 1, wherein the combustion section and the dehydroaromatization catalyst bed are in a single reactor. 3. The method of any of the preceding claims, wherein the Ci to C4 hydrocarbons comprise methane, ethane, propane, or a combination comprising at least one of the foregoing. 4. The method of any of the preceding claims, wherein the oxygen is present in the first stream an amount of 1 mole % to 10 mole %, preferably 1 mole % to 5 mole %, or 2 mole % to 5 mole %, based on the total moles present in the first stream. 5. The method of any of the preceding claims, wherein the first stream has a temperature of 400°C to 700°C prior to passing through the combustion section. 6. The method of any of the preceding claims, wherein the combustion reaction occurs in the absence of a catalyst in the combustion section. 7. The method of any of the preceding claims, wherein the combustion reaction occurs in an oxidation catalyst bed. 8. The method of any of Claims 1-5 and 7, wherein combustion section comprises an oxidation catalyst comprising platinum, redox-active oxides of iron, vanadium, nickel, ruthenium, rhodium, palladium, or a combination comprising at least one of the foregoing. 9. The method of any of the preceding claims, wherein the second stream has a temperature of 350°C to l,000°C after exiting the combustion zone. 10. The method of any of the preceding claims, wherein the third stream has a temperature of 500°C to 850°C. 11. The method of any of the preceding claims, wherein the at least one of the dehydroaromatization catalyst bed and the oxidation catalyst bed is a fixed bed. 12. The method of any of the preceding claims, wherein at least one of the dehydroaromatization catalyst bed and the oxidation catalyst bed comprises a monolith coated with a catalyst. 13. The method of any of the preceding claims, wherein the third stream comprises hydrocarbons, carbon dioxide, water, hydrogen, carbon monoxide, hydrogen, or a combination comprising at least one of the foregoing. 14. The method of any of the preceding claims, wherein the third stream comprises 85 mole % to 98 mole % of to C4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, 100 parts per million by moles to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen. 15. The method of any of the preceding claims, wherein the dehydroaromatization catalyst bed comprises a catalytic metal and a support, wherein the catalytic metal comprises at least one of molybdenum, gallium, calcium, zinc, or nickel, and wherein the support comprises at least one of zeolite Y, zeolite X, mordenite, ZSM-5, HZSM-5, ALPO-5, VPI-5, FSM-16, MCM-22, or MCM-41, preferably molybdenum and ZSM-5, or platinum, gallium, and ZSM-5. 16. The method of any of the preceding claims, wherein the fourth stream comprises aromatics, hydrogen, to C4 hydrocarbons, or a combination comprising at least one of the foregoing. 17. The method of any of the preceding claims, wherein the second stream comprises an amount of water of less than or equal to or 2.0 mole %, preferably 100 ppm to 2.0 mole %, or 0.5 mole% to 2.0 mol%, or 0.5 mole % to 1.5 mole %, based on the total moles present in the second stream; and wherein the third stream comprises 85 mole % to 98 mole % of methane; or wherein the second stream comprises an amount of water of 100 ppm to 5.0 mole %, preferably 2.0 mole% to 4.5 mole%, based on the total moles present in the second stream; and wherein the third stream comprises 85 mole % to 98 mole % of ethane, butane, and propane. 18. A method of Ci to C4 hydrocarbon dehydroaromatization, comprising: passing a first stream comprising a first portion of Ci to C4 hydrocarbons and oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section; combining the second stream with a second portion of the to C4 hydrocarbons to form a third stream; passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed; and removing the fourth stream from the dehydroaromatization catalyst bed; wherein the first stream has a temperature of 400°C to 700°C prior to passing through the combustion section; and wherein the oxygen is present in the first stream an amount of 1 mole % to 10 mole%, preferably 1 mole % to 5 mole %, or 2 mole % to 5 mole %, based on the total moles present in the first stream; and wherein the second stream has a temperature of 350°C to l,000°C after exiting the combustion zone; and wherein the third stream has a temperature of 400°C to l,000°C; and wherein the third stream comprises 85 mole % to 98 mole % of to C4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, 100 parts per million by moles to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen. 19. A system for to C4 hydrocarbon dehydroaromatization, comprising: a combustion section, through which a first stream comprising a first portion of to C4 hydrocarbons and oxygen can be passed and a combustion reaction occurs to produce a second stream that exits the combustion section; and a dehydroaromatization catalyst bed through which a third stream formed by combining the second stream and a second portion of the to C4 hydrocarbons can be passed and a dehydroaromatization reaction occurs to produce a fourth stream that exits the dehydroaromatization catalyst bed. 20. The system of Claim 19, wherein the combustion section and the dehydroaromatization catalyst bed are in a single reactor. |
BACKGROUND
[0001] Dehydroaromatization of gaseous Ci to C 4 hydrocarbons in the presence of a dehydroaromatization catalyst is a promising route for production of benzene. In the dehydroaromatization reaction, dehydroaromatization catalysts can be used to convert the Ci to C 4 hydrocarbons to aromatics, such as benzene. The dehydroaromatization reaction is highly endothermic and the thermodynamics of the reaction limit the conversion of Ci to C 4 hydrocarbons to aromatics, even at elevated temperatures of 400°C to l,000°C. For instance, at a temperature of 500°C to 800°C, the conversion of Ci to C 4 hydrocarbons to aromatics can be limited to 10 mole % to 70 mole % for the dehydroaromatization reaction. As such, heat management can present challenges. For instance, heating the feed to the reaction temperatures of 500°C to 800°C can result in high energy duties and/or metallurgical challenges, for example, due to the high reaction temperatures, special metallurgy can be required. These disadvantages can be significant in commercial scale dehydroaromatization processes.
[0002] Therefore, it would be desirable to provide improved methods for
dehydroaromatization of Ci to C 4 hydrocarbons to produce benzene.
SUMMARY
[0003] Disclosed, in various embodiments, are methods of Ci to C 4 hydrocarbon dehydroaromatization.
[0004] A method of Ci to C 4 hydrocarbon dehydroaromatization includes: passing a first stream comprising a first portion of Ci to C 4 hydrocarbons and an oxidant comprising oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section; combining the second stream with a second portion of the Ci to C 4 hydrocarbons to form a third stream; passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed; and removing the fourth stream from the dehydroaromatization catalyst bed; wherein the third stream has a temperature of 400°C to l,000°C.
[0005] A method of Ci to C 4 hydrocarbon dehydroaromatization includes: passing a first stream comprising a first portion of Ci to C 4 hydrocarbons and oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section; combining the second stream with a second portion of the to C 4 hydrocarbons to form a third stream; passing the third stream through a
dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed; and removing the fourth stream from the dehydroaromatization catalyst bed; wherein the first stream has a temperature of 400°C to 700°C prior to passing through the combustion section, and wherein the oxygen is present in the first stream an amount of 1 mole % to 10 mole %, preferably 1 mole % to 5 mole % or 2 mole % to 5 mole %, based on the total moles present in the first stream; and wherein the second stream has a temperature of 350°C to l,000°C after exiting the combustion zone; and wherein the third stream has a temperature of 400°C to l,000°C; and wherein the third stream comprises 85 mole % to 98 mole % of Ci to C 4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, up to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen; and wherein the dehydroaromatization reaction has a conversion from at least one of the foregoing methane, ethane, propane, butane, of 1 mole % to 80 mole %.
[0006] A system for Ci to C 4 hydrocarbon dehydroaromatization includes: a combustion section, through which a first stream comprising a first portion of Ci to C 4 hydrocarbons and oxygen can be passed and a combustion reaction occurs to produce a second stream that exits the combustion section; and a dehydroaromatization catalyst bed through which a third stream formed by combining the second stream and a second portion of the Ci to C 4 hydrocarbons can be passed and a dehydroaromatization reaction occurs to produce a fourth stream that exits the dehydroaromatization catalyst bed.
[0007] These and other features and characteristics are more particularly described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The following is a brief description of the drawing which are presented for the purpose of illustrating the exemplary embodiments disclosed herein and not for the purpose of limiting the same.
[0009] FIG. 1 is a schematic diagram representing a reactor for Ci to C 4 hydrocarbon dehydroaromatization.
[0010] The above described and other features are exemplified by the following detailed description, examples, and claims. DETAILED DESCRIPTION
[0011] Disclosed herein are methods for Ci to C 4 hydrocarbon dehydroaromatization. Desirably, the methods improve the heat management (e.g., heat supply) in Ci to C 4 hydrocarbon dehydroaromatization reactions. Prior processes suffered from conversions of gaseous Ci to C 4 hydrocarbons to aromatics that can be lower that desired due to
thermodynamic limitations and heat management to provide heat to the dehydroaromatization reaction can involve high energy inputs. By including a combustion reaction of a first stream comprising a first portion of Ci to C 4 hydrocarbons and an oxidant to produce a second stream, which can be combined with a second portion of the Ci to C 4 hydrocarbons, a third stream at a temperature of 400°C to l,000°C can be formed. This third stream can pass through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction can occur can convert Ci to C 4 hydrocarbon to aromatics. In this manner, heat management to provide the feed at or near the dehydroaromatization reaction temperature can be simplified and efficiently achieved.
[0012] A method of Ci to C 4 hydrocarbon dehydroaromatization includes passing a first stream comprising a first portion of Ci to C 4 hydrocarbons and an oxidant comprising oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section, combining the second stream with a second portion of the Ci to C 4 hydrocarbons to form a third stream, passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed, and removing the fourth stream from the dehydroaromatization catalyst bed. The third stream can have a temperature of 400°C to l,000°C, for example, 450°C to 950°C, or 450°C to 850°C, or 500°C to 850°C, preferably, 500°C to 800°C. When the Ci to C 4 hydrocarbons comprise greater than or equal to 75 mole %, for example, greater than or equal to 80 mole %or greater than or equal to 90 mole %, methane, the third stream can have a temperature of 600°C to l,000°C, for example, 650°C to 950°C, or 650°C to 850°C, or 700°C to 850°C, preferably, 700°C to 800°C. When the Ci to C 4 hydrocarbons comprise greater than or equal to 75 mole %, for example, greater than or equal to 80 mole %, or greater than or equal to 90 mole %, ethane, butane, propane, or a combination comprising at least one of the foregoing, the third stream can have a temperature of 400°C to 800°C, for example, 450°C to 750°C, or 450°C to 650°C, or 500°C to 650°C, preferably, 500°C to 600°C. [0013] The gaseous to C 4 hydrocarbons can include methane, ethane, propane, butane, or a combination comprising at least one of the foregoing. A first portion of the to C 4 hydrocarbons can be mixed with an oxidant to obtain a first stream.
[0014] For methane dehydroaromatization, the first stream can include methane in an amount of, for example, greater than or equal to 90 mole %, in particular, 90 mole % to 95 mole %, and C 2 to C 5 hydrocarbons, for example, in an amount of 5 mole % to 10 mole %, based on the total moles present in the first stream. For ethane dehydroaromatization, the first stream can include ethane in an amount of, for example, greater than or equal to 90 mole %, in particular, 90 mole % to 95 mole %, and and C 3 to C 5 hydrocarbons, for example, in an amount of 5 mole % to 10 mole %, based on the total moles present in the first stream.
For propane dehydroaromatization, the first stream can include propane in an amount of, for example, greater than or equal to 90 mole %, in particular, 90 mole % to 95 mole %, and Ci, C 2 , C 4 , and C 5 hydrocarbons, for example, in an amount of 5 mole % to 10 mole %, based on the total moles present in the first stream. For butane dehydroaromatization, the first stream can include butane in an amount of, for example, greater than or equal to 90 mole %, in particular, 90 mole % to 95 mole %, and Ci to C 3 and C 5 hydrocarbons, for example, in an amount of 5 mole % to 10 mole %, based on the total moles present in the first stream.
[0015] The oxidant can be an oxygen-containing compound that is capable of combusting the gaseous Ci to C 4 hydrocarbons under the combustion reaction conditions.
The oxidant can be, for example, hydrogen peroxide (H 2 0 2 ), dioxygen (0 2 ), ozone (0 3 ), an anthraquinone, a C 2-32 alkyl peroxide, a C 2-32 alkyl hydroperoxide, a C 3-32 ketone peroxide, a C 2-32 diacyl peroxide, a C 2-22 diperoxy ketal, a C 2-32 peroxyester, a C 2-32 peroxydicarbonate, a C 2-32 peroxy acid, a C 6-32 perbenzoic acid, a C 2-32 peracid, a periodinane, a periodate, or a combination comprising at least one of the foregoing.
[0016] Examples of oxidants include 2-butanone peroxide, cyclohexanone peroxide, benzoyl peroxide, lauryl peroxide, di-ieri-butyl peroxide, ieri-butyl cumyl peroxide, dicumyl peroxide, ieri-butyl hydroperoxide, cumene hydroperoxide, / <? / -butyl peroxybenzoate, tert- amyl peroxybenzoate, ieri-butyl peroxyoctoate, 2,2-di(/er/-butylperoxy)butane,
2,2-di(/er/-butylperoxy)octane, 2, 5-dimethylhexane-2, 5-dihydroperoxide,
2.5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(/er/-butylperoxy)hexane,
2.5-dimethyl-2,5-di(/er/-butylperoxy)hex-3-yne, l,4-di(/er/-butylperoxyisopropyl)benzene, 1, 3-di(/er/-butylperoxyisopropyl)benzene, di(ieri-butylperoxy) isophthalate, performic acid, peracetic acid, perpropionic acid, perbutyric acid, perisovaleric acid, perheptanoic acid, perbenzoic acid, m-chloroperbenzoic acid, monoperphthalic acid, p-methoxyperbenzoic acid, m-nitroperbenzoic acid, oc-pernaphthoic acid, b-pernaphthoic acid, bis-trimethylsilyl peroxide, bis-trimethylsilyl peroxide trimethylsilyl triphenylsilyl peroxide, potassium peroxymonosulfate, potassium permanganate, iodosylbenzene, iodosobenzene diacetate, or a combination comprising at least one of the foregoing.
[0017] The oxidant can be present in the first stream an amount of 1 mole % to 10 mole %, for example, 1 mole % to 5 mole %, or 2 mole % to 5 mole %, based on the total moles present in the first stream.
[0018] The first stream can be heated prior to being passed through the combustion section by a heat exchanger or other heating devices. Heating of the first stream can be accomplished in a furnace using flue gas generated on the shell side using hydrocarbon combustion. The temperature of the first stream can be heated to the auto-ignition temperature of the first stream. Desirably, the first stream can have a temperature of 200°C to 700°C, for example, 400°C to 700°C, prior to passing through the combustion section. For example, when the to C 4 hydrocarbons comprise greater than or equal to 75 mole %, for example, greater than or equal to 80 mole % or greater than or equal to 90 mole %, methane, the first stream can have a temperature of 400°C to 700°C, for example, 600°C to 700°C, prior to passing through the combustion section, and when the Ci to C 4 hydrocarbons comprise greater than or equal to 75 mole %, for example, greater than or equal to 80 mole % or greater than or equal to 90 mole %, ethane, butane, propane, or a combination comprising at least one of the foregoing, the first stream can have a temperature of 200°C to 500°C, for example, 400°C to 500°C, prior to passing through the combustion section.
[0019] The combustion section in which the combustion reaction occurs can be a free flame combustion section (e.g., a burner) or a combustion reactor. The combustion reaction can occur in the absence of a catalyst in the combustion section. Desirably, the combustion reaction occurs in an oxidation catalyst bed. The oxidation catalyst be can be a fixed bed or a monolith. The combustion section can include an oxidation catalyst comprising platinum, redox-active oxides of iron, vanadium, nickel, ruthenium, rhodium, palladium, or a combination comprising at least one of the foregoing.
[0020] Optionally, the first stream can be combined with hydrogen prior to passing through the combustion section. The hydrogen can be obtained from the fourth stream from the dehydroaromatization catalyst bed. The combustion section can include a fixed bed or monolith of a combustion catalyst that causes combustion of hydrogen (e.g., over gaseous Ci to C 4 hydrocarbons). [0021] The use of a fixed bed or monolith of a combustion catalyst or an oxidation catalyst allows the first stream to be at a temperature lower than the auto ignition temperature of the first stream, prior to passing through the combustion section. A combustion reaction can occur in the combustion section according to Formulae (l)-(4):
CH 4 + l.50 2 C0 + 2H 2 0 Formula (1)
C 2 H 6 + 2.50 2 2CO + 3H 2 0 Formula (2)
C 3 H 8 + 3.50 2 3CO + 4H 2 0 Formula (3)
C 4 H 10 + 4.50 2 4CO + 5H 2 0 Formula (4)
[0022] The combustion reaction produces a second stream that exits the combustion section. After exiting the combustion section, the second stream can have a temperature of 500°C to l,200°C. For example, when the to C 4 hydrocarbons comprise greater than or equal to 75 mole %, for example, greater than or equal to 80 mole % or greater than or equal to 90 mole %, methane, the second stream can have a temperature of 700°C to l,200°C, and when the Ci to C 4 hydrocarbons comprise greater than or equal to 75 mole %, for example, greater than or equal to 80 mole % or greater than or equal to 90 mole %, ethane, butane, propane, or a combination comprising at least one of the foregoing, the second stream can have a temperature of 500°C to l,000°C. The temperature of the second stream can depend on the amount of oxygen in the first stream. Desirably, the oxygen concentration can be a limiting reactant in the combustion reaction to produce carbon monoxide. The second stream can further include oxygen, Ci to C 5 hydrocarbons (i.e., hydrocarbons with 1 to 5 carbon atoms), water, or a combination comprising at least one of the foregoing.
[0023] Water can remove coke from the dehydroaromatization catalyst bed to improve stability of the dehydroaromatization catalyst bed compared to a
dehydroaromatization reaction in which the feed does not include water. For methane dehydroaromatization, a small amount water of less than or equal to or 2.0 mole %
(preferably 100 parts per million by moles (ppm) to 2.0 mole %, or 0.5 mole% to 2.0 mol%, 0.5 mole % to 1.5 mole %), based on the total moles present in the second stream can improve stability of the dehydroaromatization catalyst bed and stability of the
dehydroaromatization reaction. For dehydroaromatization of ethane, propane, butane, or a combination comprising at least one of the foregoing, an amount water of 100 ppm to 5.0 mole %, (preferably 2.0 mole% to 4.5 mole%), based on the total moles present in the second stream, can improve stability of the dehydroaromatization catalyst bed and stability of the dehydroaromatization reaction. The catalyst can be sensitive to water present in the second stream. If greater than 2.0 mole % of water for methane dehydroaromatization, or greater than 5.0 mole % of water for dehydroaromatization of ethane, propane, butane, or a combination comprising at least one of the foregoing, is present in the second stream, de- alumination can occur on the catalyst (e.g., on the zeolite) and this can permanently damage the catalyst.
[0024] The amount of water in the second stream can be controlled by adjusting the oxygen in the first stream. For instance, decreasing the amount of oxygen in the first stream can decrease the amount of water in the second stream prior to combining with the second portion of the to C 4 hydrocarbons to form a third stream. The temperature of the first stream can also be adjusted to control the amount of water in the second stream. The amount of water formed in the second stream is proportional to the amount of oxygen added to the first stream. If a lower amount of oxygen is added, the temperature of the first stream is heated to a higher temperature before entering the reactor. The oxygen concentration should desirably be optimized to control the water formation and temperature.
[0025] As the methane dehydroaromatization catalyst bed can be sensitive to water content, optionally the method can further include passing the second stream through a water-gas shift section. Sensitive to water content generally refers to the fact that the catalyst can be sensitive to water present in the first stream. The catalyst can tolerate up to 2.0 mole % of water without adverse consequences for methane dehydroaromatization, and up to 5.0 mole % of water without adverse consequences for dehydroaromatization of ethane, propane, butane, or a combination comprising at least one of the foregoing. If the water content exceeds this amount, de-alumination can occur on the catalyst (e.g., on the zeolite) which can permanently damage the catalyst.
[0026] The methane dehydroaromatization catalyst bed can include a heterogeneous catalyst. Desirably, the dehydroaromatization catalyst bed includes a catalytic metal and a support, wherein the catalytic metal comprises molybdenum, gallium, calcium, zinc, nickel, iron, copper, cobalt, rhodium, ruthenium, or a combination comprising at least one of the foregoing, and wherein the support comprises zeolite Y, zeolite X, mordenite, ZSM-5, HZSM-5, ALPO-5, VPI-5, FSM-16, MCM-22, MCM-41, or a combination comprising at least one of the foregoing. In particular, the methane dehydroaromatization catalyst bed can include molybdenum and ZSM-5.
[0027] The catalyst bed for dehydroaromatization of ethane, propane, butane, or a combination comprising at least one of the foregoing can include a heterogeneous catalyst. Desirably, the dehydroaromatization catalyst bed includes a catalytic metal and a support, wherein the catalytic metal comprises platinum, molybdenum, gallium, calcium, zinc, nickel, iron, copper, cobalt, rhodium, ruthenium, or a combination comprising at least one of the foregoing, and wherein the support comprises zeolite Y, zeolite X, mordenite, ZSM-5, HZSM-5, ALPO-5, VPI-5, FSM-16, MCM-22, MCM-41, or a combination comprising at least one of the foregoing. In particular, the C 2 - C 4 catalyst bed(s) can comprise gallium and ZSM-5, preferably platinum, gallium and ZSM-5.
[0028] In the water-gas shift section, a water-gas shift reaction of the carbon monoxide and hydrogen in the second stream occurs, producing carbon dioxide and hydrogen such that the second stream can include to C 5 hydrocarbons, carbon monoxide, carbon dioxide, water, hydrogen, oxygen, or a combination comprising at least one of the foregoing. The water-gas shift reaction can be according to Formula (5):
CO + H 2 0 C0 2 + ¾ Formula (5)
[0029] The hydrogen can be separated from the second stream and removed or combined with the first stream prior to passing through the combustion section.
[0030] The water-gas shift reaction is exothermic and produces heat such that, for a first stream comprising methane, the second stream exits the water-gas shift section with a temperature of 300°C to l,500°C, for example, 550°C to l,000°C, and for a first stream comprising ethane, propane, butane, or a combination comprising at least one of the foregoing the second stream exits the water-gas shift section with a temperature of, for example, 500°C to 700°C.
[0031] The method can further include combining the second stream with a second portion of the to C 4 hydrocarbons to form a third stream. The third stream can include hydrocarbons, carbon dioxide, water, hydrogen, carbon monoxide, or a combination comprising at least one of the foregoing. The third stream can include 85 mole % to 98 mole % of Ci to C 4 hydrocarbons, for example, 90 mole % to 95 mole % of Ci to C 4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, 100 parts per million by moles to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen, based on the total moles present in the third stream, with the total percentage of components of the third stream equaling 100 mole %. The carbon dioxide, for example, in an amount of 0.5 mole % to 5 mole %, based on the total moles present in the third stream, can reduce coke formation (i.e., coking) on the methane dehydroaromatization catalyst bed. [0032] For methane dehydroaromatization, a temperature of the third stream can be 660°C to l,000°C. A temperature of the dehydroaromatization reaction can be 660°C to l,000°C, preferably 700°C to 900°C, and a pressure of the dehydroaromatization reaction can be 101 kiloPascals to 1013 kiloPascals (kPa), preferably, 101 to 709 kiloPascals (1 to 10 atmospheres, preferably, 1 to 7 atmospheres). For dehydroaromatization of ethane, propane, butane, or a combination comprising at least one of the foregoing, temperature of the third stream can be 450°C to 800°C. A temperature of the dehydroaromatization reaction can be 450°C to 800°C, preferably 500°C to 700°C, and a pressure of the dehydroaromatization reaction can be 101 kiloPascals to 1013 kiloPascals, preferably, 101 to 709 kiloPascals (1 to 10 atmospheres, preferably, 1 to 7 atmospheres).
[0033] In the dehydroaromatization catalyst bed, a dehydroaromatization reaction occurs, producing a fourth stream that exits the dehydroaromatization catalyst bed. The fourth stream can include aromatics, hydrogen, to C 4 hydrocarbons, or a combination comprising at least one of the foregoing. The aromatics can include benzene, naphthalene, or a combination comprising at least one of the foregoing. The dehydroaromatization reaction has a conversion from methane, ethane, propane, butane, or a combination comprising at least one of the foregoing, of 1 mole % to 80 mole %; i.e., the amount of the to C 4
hydrocarbons converted during the process. For example, the dehydroaromatization reaction has a conversion from methane of 1 % to 20 mole %, for example, 5 mole % to 20 mole % or 10 mole % to 20 mole %, and the dehydroaromatization reaction has a conversion (from ethane, propane, butane, or a combination comprising at least one of the foregoing) of, for example, 20 mole % to 75 mole %, 20 mole % to 65 mole %, or 20 mole % to 55 mole %. Conversion is calculated as
(Moles of C x hydrocarbons in)-(Moles of C x hydrocarbons out )
(Moles of C x hydrocarbons in) X 100% = Conversion wherein x is 1 for methane, 2 for ethane, 3 for propane, and 4 for butane.
[0034] The combustion section and the dehydroaromatization catalyst bed can be in separate reactors. Desirably, the combustion section and the dehydroaromatization catalyst bed can be in a single reactor. At least one of the dehydroaromatization catalyst bed and the oxidation catalyst bed can be a fixed bed, a monolith coated with a catalyst, or a combination comprising at least one of the foregoing. Several catalyst layers of (optionally) combustion catalyst, (optionally) water-gas shift catalyst and alkane dehydroaromatization catalyst can be arranged in series with staged dosing of oxygen upstream of each combustion catalyst layer or burner nozzle. This limits the difference between the feed inlet temperature and the maximum temperature after passing the burning section while still obtaining high conversion Selective combustion of hydrogen in a series of layered catalyst beds consumes by-product hydrogen from the second layered catalyst bed onwards, and thereby increases the attainable equilibrium conversion of the lower alkane feed
[0035] Desirably, a method of to C 4 hydrocarbon dehydroaromatization can include passing a first stream comprising a first portion of Ci to C 4 hydrocarbons and oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section, combining the second stream with a second portion of the Ci to C 4 hydrocarbons to form a third stream, passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed, and removing the fourth stream from the dehydroaromatization catalyst bed. The first stream has a temperature of 400°C to 700°C prior to passing through the combustion section. The oxygen is present in the first stream in an amount of 1 mole % to 10 mole %, for example, 1 mole % to 5 mole % or 2 mole % to 5 mole %, based on the total moles present in the first stream. The second stream has a temperature of 350°C to l,000°C after exiting the combustion zone. The third stream has a temperature of 400°C to l,000°C and includes 85 mole % to 98 mole % of Ci to C 4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, 100 parts per million by moles to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen, based on the total moles present in the third stream, with the total percentage of components of the third stream equaling 100 mole %. The dehydroaromatization reaction has a conversion from methane, ethane, propane, butane, or a combination comprising at least one of the foregoing, of 1 mole % to 80 mole %.
[0036] A system for Ci to C 4 hydrocarbon dehydroaromatization includes a combustion section, through which a first stream comprising a first portion of Ci to C 4 hydrocarbons and oxygen can be passed and a combustion reaction occurs to produce a second stream that exits the combustion section, and a dehydroaromatization catalyst bed through which a third stream formed by combining the second stream and a second portion of the Ci to C 4 hydrocarbons can be passed and a dehydroaromatization reaction occurs to produce a fourth stream that exits the dehydroaromatization catalyst bed.
[0037] Desirably, the combustion section and the dehydroaromatization catalyst bed are in a single reactor. [0038] A more complete understanding of the components, processes, and
apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures (also referred to herein as“FIG.”) are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.
[0039] In the method illustrated in FIG.l, a first stream 2 including a first portion of Ci to C 4 hydrocarbons and an oxidant including oxygen can be passed through a combustion section 10. A combustion reaction occurs in the combustion section 10 producing a second stream 4' that exits the combustion section. The second stream 4' passes through a water-gas shift section 20 where a water-gas shift reaction of carbon monoxide and hydrogen in the second stream 4' occurs, producing carbon dioxide and hydrogen.
[0040] The second stream 4" can be combined with a second portion of Ci to C 4 hydrocarbons 22 to from a third stream 24. The third stream 24 can be passed through a dehydroaromatization catalyst bed 30, where a dehydroaromatization reaction occurs to produce a fourth stream 32 that exits the dehydroaromatization catalyst bed 30.
[0041] The methods of the present disclosure address the heat management (e.g., heat supply) challenges of Ci to C 4 hydrocarbon dehydroaromatization while improving the stability of the dehydroaromatization catalyst bed due to the production of carbon dioxide and water to be passed through in the dehydroaromatization catalyst bed.
[0042] This disclosure is further illustrated by the following examples, which are non-limiting.
EXAMPLES
Example 1
[0043] A simulated method of methane dehydroaromatization was carried out as shown in FIG. 1. Oxygen was present in the first stream 2 in an amount of 2 mole % and methane was present in the first stream 2 in an amount of 98 mole %, based on the total moles present in the first stream 2. The first stream 2 had a temperature of 650°C, prior to passing through the combustion section 10. The second stream 4' exiting the combustion section 10 had a temperature of 748°C. The second stream 4' had a composition as summarized in Table la.
[0044] The second stream 4" exiting the water-gas shift section 20 had a temperature of 752 C. The third stream 24 had a composition as summarized in Table lb.
[0045] The first stream was heated in a furnace using flue gas generated on the shell side using hydrocarbon combustion. The first stream was heated to 650°C. A temperature of the third stream was 752°C. A temperature of the dehydroaromatization reaction including a catalyst comprising Mo/ZSM-5 was 750°C, and a pressure of the dehydroaromatization reaction was 101 KiloPascals (1 atmosphere). The conversion of methane was 10 mole % ((96.7 moles Ci hydrocarbon in - 87.0 moles Ci hydrocarbon out) / (96.7 moles Ci hydrocarbon in)). The fourth stream 32 exiting the dehydroaromatization reactor had a composition as summarized in Table lc.
Example 2
[0046] A simulated method of ethane dehydroaromatization was carried out as shown in FIG. 1. Oxygen was present in the first stream 2 in an amount of 2.5 mole % and ethane was present in the first stream 2 in an amount of 97.5 mole %, based on the total moles present in the first stream 2. The first stream 2 had a temperature of 450°C, prior to passing through the combustion section 10. The second stream 4' exiting the combustion section 10 had a temperature of 533°C. The second stream 4' had a composition as summarized in Table 2a.
[0047] The second stream 4" exiting the water-gas shift section 20 had a temperature of 539 C. The third stream 24 had a composition as summarized in Table 2b.
[0048] The first stream was heated in a furnace using flue gas generated on the shell side using hydrocarbon combustion. The first stream was heated to 450°C. A temperature of the third stream was 539°C. A temperature of the dehydroaromatization reaction including a catalyst comprising Pt-Ga/ZSM-5 was 550°C, and a pressure of the dehydroaromatization reaction was 101 KiloPascals (1 atmosphere). The conversion of ethane was 50 mole % ((96.5 moles C 2 hydrocarbon in - 48.3 C 2 hydrocarbon out) / (96.5 moles C 2 hydrocarbon in)). The fourth stream 32 exiting the dehydroaromatization reactor had a composition as summarized in Table 2c.
Example 3
[0049] A simulated method of propane dehydroaromatization was carried out as shown in FIG. 1. Oxygen was present in the first stream 2 in an amount of 3.5 mole % and propane was present in the first stream 2 in an amount of 96.5 mole %, based on the total moles present in the first stream 2. The first stream 2 had a temperature of 450°C, prior to passing through the combustion section 10. The second stream 4' exiting the combustion section 10 had a temperature of 53l°C. The second stream 4' had a composition as summarized in Table 3 a.
[0050] The second stream 4" exiting the water-gas shift section 20 had a temperature of 537 C. The third stream 24 had a composition as summarized in Table 3b.
[0051] The first stream was heated in a furnace using flue gas generated on the shell side using hydrocarbon combustion. The first stream was heated to 450°C. A temperature of the third stream was 537°C. A temperature of the dehydroaromatization reaction including a catalyst comprising Pt-Ga/ZSM-5 was 530°C, and a pressure of the dehydroaromatization reaction was 101 KiloPascals (1 atmosphere). The conversion of propane was 60 mole % ((95.5 moles C 3 hydrocarbon in - 38.2 C 3 hydrocarbon out) / (95.5 moles C 3 hydrocarbon in)). The fourth stream 32 exiting the dehydroaromatization reactor had a composition as summarized in Table 3c.
Example 4
[0052] A simulated method of butane dehydroaromatization was carried out as shown in FIG. 1. Oxygen was present in the first stream 2 in an amount of 4.5 mole % and butane was present in the first stream 2 in an amount of 95.5 mole %, based on the total moles present in the first stream 2. The first stream 2 had a temperature of 450°C, prior to passing through the combustion section 10. The second stream 4' exiting the combustion section 10 had a temperature of 530°C. The second stream 4' had a composition as summarized in Table 4a.
[0053] The second stream 4" exiting the water-gas shift section 20 had a temperature of 536 C. The third stream 24 had a composition as summarized in Table 4b.
[0054] The first stream was heated in a furnace using flue gas generated on the shell side using hydrocarbon combustion. The first stream was heated to 450°C. A temperature of the third stream was 536°C. A temperature of the dehydroaromatization reaction including a catalyst comprising Pt-Ga/ZSM-5 was 530°C, and a pressure of the dehydroaromatization reaction was 101 KiloPascals (1 atmosphere). The conversion of butane was 70 mole % ((94.5 moles C 4 hydrocarbon in - 28.4 moles C 4 hydrocarbon out) / (94.5 moles C 4 hydrocarbon in)). The fourth stream 32 exiting the dehydroaromatization reactor had a composition as summarized in Table 4c.
[0055] The processes disclosed herein include(s) at least the following aspects:
[0056] Aspect 1: A method of Ci to C 4 hydrocarbon dehydroaromatization, comprising: passing a first stream comprising a first portion of Ci to C 4 hydrocarbons and an oxidant comprising oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section; combining the second stream with a second portion of the Ci to C 4 hydrocarbons to form a third stream; passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed; and removing the fourth stream from the dehydroaromatization catalyst bed; wherein the third stream has a temperature of 400°C to l,000°C.
[0057] Aspect 2: The method of Aspect 1, wherein the combustion section and the dehydroaromatization catalyst bed are in a single reactor.
[0058] Aspect 3: The method of any of the preceding aspects, wherein the Ci to C 4 hydrocarbons comprise methane, ethane, propane, or a combination comprising at least one of the foregoing.
[0059] Aspect 4: The method of any of the preceding aspects, wherein the oxygen is present in the first stream an amount of 1 mole % to 10 mole %, preferably 1 mole % to 5 mole % or 2 mole % to 5 mole %, based on the total moles present in the first stream.
[0060] Aspect 5: The method of any of the preceding aspects, wherein the first stream has a temperature of 400°C to 700°C prior to passing through the combustion section.
[0061] Aspect 6: The method of any of the preceding aspects, wherein the combustion reaction occurs in the absence of a catalyst in the combustion section. [0062] Aspect 7: The method of any of the preceding aspects, wherein the
combustion reaction occurs in an oxidation catalyst bed.
[0063] Aspect 8: The method of any of Aspects 1-5 and 7, wherein combustion section comprises an oxidation catalyst comprising platinum, redox-active oxides of iron, vanadium, nickel, ruthenium, rhodium, palladium, or a combination comprising at least one of the foregoing.
[0064] Aspect 9: The method of any of the preceding aspects, wherein the second stream has a temperature of 350°C to l,000°C after exiting the combustion zone.
[0065] Aspect 10: The method of any of the preceding aspects, wherein the third stream has a temperature of 500°C to 850°C.
[0066] Aspect 11: The method of any of the preceding aspects, wherein the at least one of the dehydroaromatization catalyst bed and the oxidation catalyst bed is a fixed bed.
[0067] Aspect 12: The method of any of the preceding aspects, wherein at least one of the dehydroaromatization catalyst bed and the oxidation catalyst bed comprises a monolith coated with a catalyst.
[0068] Aspect 13: The method of any of the preceding aspects, wherein the third stream comprises hydrocarbons, carbon dioxide, water, hydrogen, carbon monoxide, hydrogen, or a combination comprising at least one of the foregoing.
[0069] Aspect 14: The method of any of the preceding aspects, wherein the third stream comprises 85 mole % to 98 mole % of Ci to C 4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, 100 parts per million by moles to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen.
[0070] Aspect 15: The method of any of the preceding aspects, wherein the dehydroaromatization catalyst bed comprises a catalytic metal and a support, wherein the catalytic metal comprises at least one of molybdenum, gallium, calcium, zinc, or nickel, and wherein the support comprises at least one of zeolite Y, zeolite X, mordenite, ZSM-5, HZSM-5, ALPO-5, VPI-5, FSM-16, MCM-22, or MCM-41, preferably the catalytic metal comprises molybdenum and ZSM-5, or preferably the catalytic metal comprises platinum, gallium, and ZSM-5.
[0071] Aspect 16: The method of any of the preceding aspects, wherein the fourth stream comprises aromatics, hydrogen, Ci to C 4 hydrocarbons, or a combination comprising at least one of the foregoing. [0072] Aspect 17: The method of any of the preceding aspects, wherein the dehydroaromatization reaction has a conversion from methane, ethane, propane, butane, or a combination comprising at least one of the foregoing of 1 mole % to 80 mole %.
[0073] Aspect 18: The method of any of the preceding aspects, wherein the second stream comprises an amount of water of less than or equal to or 2.0 mole %, preferably 100 ppm to 2.0 mole %, or 0.5 mole% to 2.0 mol%, or 0.5 mole % to 1.5 mole %, based on the total moles present in the second stream; wherein the third stream comprises 75 mole % to 98 mole %, preferably 85 mole % to 98 mole %, of methane, based on the total moles present in the second stream; and preferably wherein the dehydroaromatization catalyst bed comprises molybdenum and ZSM-5.
[0074] Aspect 19: The method of any of Aspects 1 - 17, wherein the second stream comprises an amount of water of 100 ppm to 5.0 mole %, preferably 2.0 mole% to 4.5 mole%, based on the total moles present in the second stream; wherein the third stream comprises 75 mole % to 98 mole %, preferably 85 mole % to 98 mole %, of ethane, butane, and propane, based on the total moles present in the second stream; and preferably wherein the dehydroaromatization catalyst bed comprises platinum, gallium, and ZSM-5.
[0075] Aspect 20: The method of Aspect 19, wherein the third stream comprises 75 mole % to 98 mole %, preferably 85 mole % to 98 mole %, of ethane, based on the total moles present in the second stream.
[0076] Aspect 21: The method of Aspect 19, wherein the third stream comprises 75 mole % to 98 mole %, preferably 85 mole % to 98 mole %, of butane, based on the total moles present in the second stream.
[0077] Aspect 22: The method of Aspect 19, wherein the third stream comprises 75 mole % to 98 mole %, preferably 85 mole % to 98 mole %, of propane, based on the total moles present in the second stream.
[0078] Aspect 23: A method of to C 4 hydrocarbon dehydroaromatization, comprising: passing a first stream comprising a first portion of Ci to C 4 hydrocarbons and oxygen through a combustion section, wherein a combustion reaction occurs producing a second stream that exits the combustion section; combining the second stream with a second portion of the to C 4 hydrocarbons to form a third stream; passing the third stream through a dehydroaromatization catalyst bed, wherein a dehydroaromatization reaction occurs producing a fourth stream that exits the dehydroaromatization catalyst bed; and removing the fourth stream from the dehydroaromatization catalyst bed; wherein the first stream has a temperature of 400°C to 700°C prior to passing through the combustion section, and wherein the oxygen is present in the first stream an amount of 1 mole % to 10 mole %, preferably 1 mole % to 5 mole % or 2 mole % to 5 mole %, based on the total moles present in the first stream; and wherein the second stream has a temperature of 350°C to l,000°C after exiting the combustion zone; and wherein the third stream has a temperature of 400°C to l,000°C; and wherein the third stream comprises 85 mole % to 98 mole % of to C 4 hydrocarbons, 0.5 mole % to 5 mole % carbon dioxide, 100 parts per million by moles to 5.0 mole % water, 0.5 mole % to 5 mole % or 1 mole % to 5 mole % hydrogen. Preferably wherein the dehydroaromatization reaction has a conversion from methane, ethane, propane, butane, or a combination comprising at least one of the foregoing, of 1 mole % to 80 mole %.
[0079] Aspect 24: A system for to C 4 hydrocarbon dehydroaromatization, comprising: a combustion section, through which a first stream comprising a first portion of Ci to C 4 hydrocarbons and oxygen can be passed and a combustion reaction occurs to produce a second stream that exits the combustion section; and a dehydroaromatization catalyst bed through which a third stream formed by combining the second stream and a second portion of the Ci to C 4 hydrocarbons can be passed and a dehydroaromatization reaction occurs to produce a fourth stream that exits the dehydroaromatization catalyst bed.
[0080] Aspect 25: The system of Aspect 24, wherein the combustion section and the dehydroaromatization catalyst bed are in a single reactor.
[0081] In general, the invention may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The invention may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present invention. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of“less than or equal to 25 wt%, or 5 wt% to 20 wt%,” is inclusive of the endpoints and all intermediate values of the ranges of“5 wt% to 25 wt%,” etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. “Combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms “first,”“second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to denote one element from another. The terms“a” and“an” and“the” herein do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or.” The suffix“(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the film(s) includes one or more films). Reference throughout the specification to“one embodiment”, “another embodiment”,“an embodiment”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. It is noted that the
composition of all streams herein total 100 mole%.
[0082] The modifier“about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). The notation“+ 10%” means that the indicated measurement can be from an amount that is minus 10% to an amount that is plus 10% of the stated value. The terms“front”,“back”,“bottom”, and/or“top” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation.“Optional” or“optionally” means that the
subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A“combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.
[0083] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.
[0084] While particular embodiments have been described, alternatives,
modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.
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