Conversion of Ethanol to Isobutanol

Abstract

A method for isobutanol synthesis is described. Ethanol and syngas (synthesis gas) are reacted in a first reaction zone in the presence of a multiphase catalyst. The product of the first reaction can be separated into one or more streams comprising methanol and propanol. The methanol and propanol from the first reaction are reacted in the presence of a second catalyst to form isobutanol in a second reaction zone.

Description

BACKGROUND OF THE INVENTION

[0001] Ethanol is mainly used as a gasoline additive for improving combustion efficiency. Isobutanol can be considered a second-generation biofuel. Isobutanol is an organic solvent and a raw material in the manufacture of isobutyl acetate and isobutyl esters. It can also be directly blended with gasoline to improve the octane number and combustion efficiency or used as a pure alternative fuel. Compared with ethanol, isobutanol has a relatively higher energy density and lower volatility. In addition, it does not easily absorb water from the air, preventing corrosion of engines and pipelines. It also has a higher octane number than ethanol, resulting in less engine knocking.

[0002] Although isobutanol has many potential uses, its synthesis is currently limited. Isobutanol can be prepared by the carbonylation of propylene. This method involves reacting propylene with carbon monoxide and hydrogen to form isobutyraldehyde, and then hydrogenating isobutyraldehyde to isobutanol. For example, U.S. Patent No. 2,564,130 discloses a method for preparing n-butanol and isobutanol from a mixture containing propylene, CO, and H2 in the presence of a cobalt-containing catalyst at 225°C to 300°C. Although this carbonylation method is currently used to prepare butanol, it is not energy-efficient due to the high energy required to produce propylene and synthesis gas (syngas). It is also expensive due to the cost of propylene. In addition, when isobutanol is used as a gasoline additive, it is expected that the demand for it will significantly increase the demand for propylene, making the method even more expensive.

[0003] Alternatively, the direct synthesis of isobutanol from the more abundant and cheaper syngas has been widely studied. Syngas containing carbon monoxide and hydrogen is mainly prepared by the reforming or partial oxidation of natural gas and light hydrocarbons, or the gasification of coal and biomass at high temperatures. It can also be prepared by the gasification of municipal solid waste. Carbon monoxide and hydrogen react on alkali metal-promoted ZnO- and CuO-ZnO-based catalysts at high temperature and pressure to prepare methanol and isobutanol, with methane and light hydrocarbons as the main by-products. For example, U.S. Patent No. 5,767,166 discloses a method for preparing isobutanol from syngas on an alkali metal-promoted Zn-Cr oxide catalyst in a single reactor. A similar method is disclosed in Chinese Patent Publication No. 103,272,609, in which a CuO-ZnO-ZrO2 catalyst promoted by alkali metals and rare earth metal oxides is used.

[0004] Although the direct synthesis of isobutanol from syngas has been widely studied, it is generally associated with poor isobutanol selectivity and productivity. During operation, lower temperatures result in higher methanol selectivity, while higher temperatures tend to produce more methane and light hydrocarbons. Therefore, it is difficult to achieve high isobutanol selectivity and yield on alkali metal-promoted ZnO and CuO-ZnO catalysts.

[0005] Therefore, there is a need for a method that can overcome the above obstacles and achieve a high isobutanol productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a diagram of an embodiment of a method for preparing isobutanol from ethanol and syngas according to the present invention.

[0007] Figure 2 is a diagram of another embodiment of a method for preparing isobutanol from ethanol and syngas according to the present invention.

[0008] DESCRIPTION

[0009] New routes for isobutanol synthesis have been developed. It involves a first reaction between ethanol and syngas (synthesis gas) in the presence of a heterogeneous catalyst to prepare an alcohol mixture containing methanol, propanol, and butanol. The syngas is a gas mixture composed of hydrogen, carbon monoxide, and sometimes a small amount of carbon dioxide. The product of the first reaction can be separated into one or more streams containing methanol and propanol. Methanol and propanol from the first reaction are reacted in the presence of a second catalyst to form isobutanol in a second reaction.

[0010] The first step of the method is to react ethanol and syngas to prepare propanol. The reaction is as follows:

[0011] C2H5OH + 2CO + H2 = C3H7OH + CO2 (1)

[0012] C2H5OH + CO + 2H2 = C3H7OH + H2O (2)

[0013] Methanol is also prepared as a by-product from the syngas:

[0014] CO + 2H2 = CH3OH (3)

[0015] The reaction mixture from the first reaction zone can be separated into a gas stream and a liquid stream in a gas-liquid separator. The gas stream can contain CO2, light hydrocarbons, and unreacted CO and H2. The unreacted CO and H2 will be separated and recycled to the first reaction zone.

[0016] The liquid bottom stream contains the mixed alcohols separated in the liquid separation zone. The liquid separation zone may include one or more distillation columns. In one embodiment, the liquid bottom stream is separated into individual streams of methanol, ethanol, propanol, isobutanol, and n-butanol. A portion of the methanol stream and the propanol stream may be sent to a second reaction zone where they react in the presence of a second catalyst to produce isobutanol. The remaining portion of the methanol stream and the unreacted ethanol stream may be recycled to the first reaction zone. Optionally, the remaining portion of the methanol stream may be collected as a by-product. The isobutanol stream is collected as a product, while the n-butanol stream is collected as a by-product.

[0017] The reaction of propanol and methanol in the second reaction zone may be carried out in the presence of an inert gas (such as N2 and Ar), CO, H2, or a combination thereof. The reaction is as follows:

[0018] C3H7OH + CH3OH = i-C4H9OH + H2O (4)

[0019] The reaction mixture prepared in the second reaction zone may be recycled to the liquid separation zone for alcohol separation, recycling, and product collection. Optionally, it may also be introduced into a second liquid separation zone for alcohol separation. In this embodiment, methanol is collected as a by-product or recycled to the first reaction zone; ethanol is recycled to the first reaction zone; propanol is recycled to the second reaction zone; and isobutanol is collected as a product.

[0020] One aspect of the present invention is a method for producing isobutanol. In one embodiment, the method includes: reacting ethanol with syngas in a first reaction zone in the presence of a multiphase catalyst under first reaction conditions to produce a first reaction mixture containing methanol and propanol; separating the first reaction mixture into at least a methanol stream containing methanol, an ethanol stream containing ethanol, and a propanol stream containing propanol; introducing the methanol stream and the propanol stream into a second reaction zone; and reacting methanol and propanol in the second reaction zone in the presence of a second catalyst under second reaction conditions to produce a second reaction mixture containing isobutanol.

[0021] In some embodiments, the multiphase catalyst comprises at least one of the following: elements selected from Cu, Ag, Au, Zn, Rh, Pd, Pt, Cr, Mn, Fe, Co, Ni, Al, Si, Zr, Ti, and combinations thereof; alkali metal oxides and salts, alkaline earth metal oxides and salts, rare earth metal oxides and salts, and combinations thereof.

[0022] In some embodiments, the multiphase catalyst comprises at least one of an alkali metal oxide-doped Cu catalyst, an alkali metal oxide-doped Zn catalyst, an alkali metal oxide-doped Pd catalyst, and combinations thereof.

[0023] In some embodiments, the multiphase catalyst comprises a catalyst based on K2O / CuZnAlO x or a catalyst based on K2O / CuZnCrO x

[0024] In some embodiments, the second catalyst comprises at least one element from Group IA, IIA, IIIA, IVA, VA, IV, IB, IIB, VIB, VIIB, or VIIIB of the periodic table and combinations thereof.

[0025] In some embodiments, the second catalyst comprises at least one of the following: MgO, MgO-Al2O3, CuO-MgO-Al2O3, Mg-PO4, Ca-PO4, Sr-PO4, magnetically metal oxide-doped zeolites, and combinations thereof.

[0026] In some embodiments, separating the first reaction mixture into at least the methanol stream, the ethanol stream, and the propanol stream comprises: separating the first reaction mixture into an overhead gas stream and a liquid bottom stream comprising at least methanol, ethanol, and propanol in a gas-liquid separation zone; and separating the liquid bottom stream into at least the methanol stream, the ethanol stream, the propanol stream, an isobutanol stream comprising isobutanol, and a n-butanol stream comprising n-butanol in a liquid separation zone.

[0027] In some embodiments, the method further comprises: separating the overhead gas stream into a first gas stream comprising CO2 and light hydrocarbons and a recycle synthesis gas stream comprising CO and H2; and recycling the recycle synthesis gas stream to the first reaction zone.

[0028] In some embodiments, separating the liquid bottom stream comprises using an adsorption process or a distillation process.

[0029] In some embodiments, the second reaction mixture further comprises unreacted methanol and unreacted propanol, and further comprises: recycling the second reaction mixture to the liquid separation zone.

[0030] ​In some embodiments, the second reaction mixture further comprises unreacted methanol and unreacted propanol, and further includes: separating the second reaction mixture in a second liquid separation zone into an unreacted methanol stream comprising unreacted methanol, an unreacted propanol stream comprising unreacted propanol, a second isobutanol stream comprising isobutanol, and a second n-butanol stream comprising n-butanol; and optionally combining the isobutanol stream with the second isobutanol stream.

[0031] In some embodiments, the method further includes: recycling the unreacted methanol stream to the first reaction zone; and recycling the unreacted propanol stream to the second reaction zone.

[0032] In some embodiments, the method further includes: recycling the ethanol stream to the first reaction zone.

[0033] In some embodiments, the first reaction conditions include at least one of the following: a temperature in the range of about 200 °C to about 500 °C; a pressure in the range of about 0.1 MPa to about 30 MPa; 0.1 mol% to 50 mol% ethanol and a balance of syngas having a H2 to CO ratio in the range of about 5:1 to about 1:5; or a gas hourly space velocity in the range of about 100 to about 500,000 liters of gas per kilogram of catalyst per hour (L / kg-h).

[0034] In some embodiments, the second reaction conditions include at least one of the following: a temperature in the range of about 100 °C to about 500 °C; a pressure in the range of about 0.1 MPa to about 15 MPa; 0.1 mol% to 99 mol% methanol and 0.1 mol% to 99 mol% propanol; or a gas hourly space velocity in the range of about 100 to about 300,000 liters of gas per kilogram of catalyst per hour (L / kg-h).

[0035] Another aspect of the present invention is a method for producing isobutanol. In one embodiment, the method includes: reacting ethanol with syngas in a first reaction zone in the presence of a multiphase catalyst under first reaction conditions to prepare a first reaction mixture comprising methanol and propanol; separating the first reaction mixture into an overhead gas stream and a liquid bottom stream comprising at least methanol, ethanol, propanol, isobutanol, and n-butanol; separating the liquid bottom stream in a liquid separation zone into at least a methanol stream comprising methanol, an ethanol stream comprising ethanol, a propanol stream comprising propanol, an isobutanol stream comprising isobutanol, and an n-butanol stream comprising n-butanol; introducing at least a portion of the methanol stream and the propanol stream into a second reaction zone; and reacting methanol and propanol in the second reaction zone in the presence of a second catalyst under second reaction conditions to prepare a second reaction mixture comprising isobutanol.

[0036] In some embodiments, the method further comprises: recycling the second reaction mixture to the liquid separation zone; and optionally at least one of the following: recycling the ethanol stream to the first reaction zone; and recycling a second portion of the methanol stream to the first reaction zone.

[0037] In some embodiments, the method further comprises: separating the second reaction mixture in a second liquid separation zone into an unreacted methanol stream comprising unreacted methanol, an unreacted propanol stream comprising unreacted propanol, a second isobutanol stream comprising isobutanol, and a second n-butanol stream comprising n-butanol.

[0038] In some embodiments, the method further comprises: separating the top gas stream into a first gas stream comprising CO2 and light hydrocarbons and a recycle syngas stream comprising CO and H2; and recycling the recycle syngas stream to the first reaction zone.

[0039] In some embodiments, the first reaction conditions include at least one of the following: a temperature in the range of about 200 °C to about 500 °C; a pressure in the range of about 0.1 MPa to about 30 MPa; 0.1 mol% to 50 mol% ethanol and a balance of syngas having a H2 to CO ratio in the range of about 5:1 to about 1:5; or a gas hourly space velocity in the range of about 100 to about 500,000 liters of gas per kilogram of catalyst per hour (L / kg-h); or wherein the second reaction conditions include at least one of the following: a temperature in the range of about 100 °C to about 500 °C; a pressure in the range of about 0.1 MPa to about 15 MPa; 0.1 mol% to 99 mol% methanol and 0.1 mol% to 99 mol% propanol; or a gas hourly space velocity in the range of about 100 to about 300,000 liters of gas per kilogram of catalyst per hour (L / kg-h).

[0040] Figure 1 An embodiment of a method 100 for preparing isobutanol is shown. An ethanol stream 105 and a syngas stream 110 are fed to a first reaction zone 115 comprising at least one reactor and associated equipment.

[0041] Ethanol from any suitable source can be used. Ethanol is typically prepared by fermentation of sugars and starches and by hydration of ethylene. In addition, other processes such as fermentation of syngas and conversion of biomass to ethanol are also being commercialized. With rapid technological development, ethanol can be produced from a wide variety of feedstocks such as traditional crops or fossil feedstocks, whole lignocellulosic biomass, and waste materials. This diversification of feedstocks for ethanol production will allow the demand for ethanol not to compete with food.

[0042] Syngas from any suitable source can be used. Syngas can be prepared by reforming, partial oxidation of natural gas and light hydrocarbons, or gasification of coal or biomass at high temperatures. It can also be prepared by gasification of municipal solid waste. Accordingly, the method can be applied to the process of converting coal, natural gas, biomass, and / or waste into isobutanol. The syngas typically has a molar ratio of H2 to CO in the range of about 5:1 to about 1:5 or about 3:1 to about 1:3.

[0043] The first reaction zone 115 typically contains 0.1 mol% to 50 mol% ethanol and 50 mol% to 99.9 mol% syngas, or 1 mol% to 25 mol% ethanol and 75 mol% to 99 mol% syngas. Ethanol and syngas react in the presence of a multiphase catalyst to prepare a first reaction mixture containing methanol and propanol. The first reaction mixture may also contain butanol, CO2, light hydrocarbons, H2O, unreacted ethanol, and syngas.

[0044] Suitable catalysts for the first reaction include, but are not limited to, Cu, Ag, Au, Zn, Rh, Pd, Pt, Cr, Mn, Fe, Co, Ni, Al, Si, Zr, Ti, alkali metal oxides and salts, alkaline earth metal oxides and salts, rare earth metal oxides and salts, or combinations thereof. In some embodiments, a Cu catalyst promoted with an alkali metal oxide, a Zn catalyst promoted with an alkali metal oxide, and a Pd catalyst promoted with an alkali metal oxide are used. An example of a suitable catalyst is a catalyst based on K2O / CuZnAlO x catalyst.

[0045] The reaction conditions in the first reaction zone 115 can include at least one of the following: a reaction temperature in the range of about 200 °C to about 500 °C or 250 °C to 450 °C; a pressure in the range of about 0.1 MPa to about 30 MPa or 0.5 MPa to 15 MPa; or a gas hourly space velocity in the range of about 100 to about 500,000 or 1000 to 200,000 liters of gas per kilogram of catalyst per hour (L / kg-h).

[0046] The first reaction mixture 120 from the first reaction zone can be sent to a gas-liquid separation zone 125 and separated into an overhead gas stream 130 and a liquid bottom stream 135. Suitable gas-liquid separation zones 125 include, but are not limited to, condensate tanks and reactors.

[0047] The top gas stream 130 typically contains one or more of H2, CO, CO2, and light hydrocarbons. The top gas stream 130 can be separated in the gas separation zone 140 into a recycle synthesis gas stream 145 containing H2 and CO and a gas stream 150 containing CO2 and light hydrocarbons. The recycle synthesis gas stream 145 can be recycled to the first reaction zone 115. The gas stream 150 can be used as a fuel gas to provide energy for the process of converting ethanol to isobutanol. Suitable gas separation zones 140 include, but are not limited to, membrane separation processes and adsorption-desorption processes.

[0048] The liquid bottom stream 135 typically contains methanol, ethanol, propanol, isobutanol, and n-butanol. The liquid bottom stream 135 can be separated in the liquid separation zone 155. Suitable liquid separation zones 155 include, but are not limited to, an adsorption zone including one or more adsorption beds and a distillation zone including one or more distillation columns.

[0049] In one embodiment, the liquid bottom stream 135 can be separated into a methanol stream 160 containing methanol, an ethanol stream 165 containing ethanol, a propanol stream 170 containing propanol, an isobutanol stream 175 containing isobutanol, and an n-butanol stream 180 containing n-butanol. The methanol stream 160 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% methanol. The ethanol stream 165 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% ethanol. The propanol stream 170 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% propanol. The isobutanol stream 175 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% isobutanol. The n-butanol stream 180 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% n-butanol.

[0050] The methanol stream 160 can be divided into two parts 185, 190. The first part 185 of the methanol stream 160 and the propanol stream 170 can be mixed to prepare a methanol-propanol stream 195. The molar ratio of propanol to methanol can be adjusted to meet the requirements in the second reaction zone 200.

[0051] A second portion 190 of the methanol stream 160 can be collected as a by-product (not shown) or mixed with the ethanol stream 165 to form a methanol-ethanol stream 205. The methanol-ethanol stream 205 can be recycled to the first reaction zone 115.

[0052] The isobutanol stream 175 is collected as a product, while the n-butanol stream 180 is collected as a by-product.

[0053] The methanol-propanol stream 195 can be sent to a second reaction zone 200 where they are reacted in the presence of a second catalyst to produce a second reaction mixture 210 comprising isobutanol. In the second reaction zone 200, there can be 0.1 mol% to 99.9 mol% methanol and 0.1 mol% to 99.9 mol% propanol, or 5 mol% to 95 mol% methanol and 5 mol% to 95 mol% propanol, or 10 mol% to 90 mol% methanol and 10 mol% to 90 mol% propanol, or 20 mol% to 80 mol% methanol and 20 mol% to 80 mol% propanol, or 25 mol% to 75 mol% methanol and 25 mol% to 75 mol% propanol, or 30 mol% to 75 mol% methanol and 25 mol% to 70 mol% propanol, or 40 mol% to 75 mol% methanol and 25 mol% to 60 mol% propanol, or 50 mol% to 75 mol% methanol and 25 mol% to 50 mol% propanol. The second reaction mixture 210 can also contain water, unreacted methanol, and unreacted propanol.

[0054] The second reaction can be carried out in the presence of an inert gas (such as N2 and Ar), CO, H2, or a combination thereof.

[0055] The second catalyst comprises at least one element from groups IA, IIA, IIIA, IVA, VA, IV, IB, IIB, VIB, VIIB, and VIIIB of the periodic table. Suitable catalysts include, but are not limited to, MgO, MgO-Al2O3, CuO-MgO-Al2O3, Mg-PO4, Ca-PO4, Sr-PO4, alkali metal zeolites, or combinations thereof. The second catalyst can be heterogeneous or homogeneous.

[0056] The second reaction conditions in the second reaction zone 200 include one or more of the following: a temperature in the range of 100 °C to 500 °C, or 150 °C to 450 °C; a pressure in the range of 0.1 MPa to about 15 MPa, or 0.1 MPa to 10 MPa; or a gas hourly space velocity in the range of about 100 to about 300000, or 1000 to about 150000 liters of gas per kilogram of catalyst per hour (L / kg-h).

[0057] The second reaction mixture 210 mainly containing butanol and unreacted methanol and propanol from the second reaction zone 200 can be sent to the liquid separation zone 155.

[0058] Figure 2 Another embodiment of the method 250 for producing isobutanol is shown. The same numbers as Figure 1 in are used to identify the corresponding streams and equipment.

[0059] In this embodiment, the second reaction mixture 210 from the second reaction zone 200 is sent to the second liquid separation zone 255. Suitable second liquid separation zones 255 include, but are not limited to, an adsorption zone including one or more adsorption beds and a distillation zone including one or more distillation columns.

[0060] The second reaction mixture 210 is separated into a second methanol stream 260, a second propanol stream 265, a second isobutanol stream 270, and a second n-butanol stream 275. The second methanol stream 260 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% methanol. The second propanol stream 265 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% propanol. The second isobutanol stream 270 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% isobutanol. The second n-butanol stream 275 can contain at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 98%, or at least 99% n-butanol.

[0061] The second methanol stream 260 can be combined with the methanol-ethanol stream 205 and sent to the first reaction zone 115.

[0062] The second propanol stream 265 is combined with the methanol-propanol stream 195 and sent to the second reaction zone 200.

[0063] The second isobutanol stream 270 is combined with the isobutanol stream 175 to form a combined isobutanol stream 280. The combined isobutanol stream 280 is collected as a product.

[0064] The second n-butanol stream 275 is combined with the n-butanol stream 180 to form a combined n-butanol stream 285, which is collected as a by-product. Examples

[0065] Example 1

[0066] The CuO-ZnO-Al2O3 catalyst was prepared by a conventional co-precipitation method. Then, K2O was impregnated on the surface by the incipient wetness impregnation method. The catalyst has a composition of 3% K2O, 62% CuO, 25% ZnO, and 10% Al2O3. The catalyst was tested in a tubular reactor under the conditions of 340 °C, 100 atm, 43% H2, 43% CO, 5% C2H5OH, 9% N2, and a gas hourly space velocity of 4000 ml / g-h. A CO conversion rate of 33% and an ethanol conversion rate of 83% were achieved. The yields of methanol, propanol, and isobutanol were 201 g / kg-h, 173 g / kg-h, and 24 g / kg-h, respectively. Apparently, ethanol was mainly converted to propanol (173 g / kg-h) by reacting with syngas.

[0067] Example 2

[0068] The CuO-ZnO-Cr2O3 catalyst was prepared by a conventional co-precipitation method. Then, K2O was impregnated on the surface by the incipient wetness impregnation method. The catalyst has a composition of 3% K2O, 58% CuO, 30% ZnO, and 9% Cr2O3. The catalyst was tested in a tubular reactor under the conditions of 370 °C, 100 atm, 43.5% H2, 43.5% CO, 3.5% C2H5OH, 9.5% N2, and a gas hourly space velocity of 4000 m1 / g-h. A CO conversion rate of 32% and an ethanol conversion rate of 93% were achieved. The yields of methanol, propanol, isobutanol, and n-butanol were 89 g / kg-h, 118 g / kg-h, 51 g / kg-h, and 16 g / kg-h, respectively. Apparently, ethanol was mainly converted to propanol (118 g / kg-h) by reacting with syngas.

[0069] Example 3

[0070] The CuO-MgO-Al2O3 catalyst was prepared by a conventional co-precipitation method. The catalyst has a composition of 0.1% CuO, 61.2% MgO, and 38.7% Al2O3. The catalyst was tested in a tubular reactor under the conditions of 387 °C, 1 atm, 7.8% C3H7OH, 41.1% CH3OH, the balance N2, and a gas hourly space velocity of 4000 ml / g-h. An 85% C3H7OH conversion rate and a 40% CH3OH conversion rate were achieved. The isobutanol yield was 352 g / kg-h. Apparently, propanol was converted to isobutanol by reacting with methanol.

[0071] Example 4

[0072] The CuO-MgO-Al2O3 catalyst was prepared by a conventional co-precipitation method. The catalyst has a composition of 16.7% CuO, 51.0% MgO and 32.3% Al2O3. The catalyst was tested in a tubular reactor under the conditions of 322 °C, 1 atm, 7.8% C3H7OH, 41.1% CH3OH, the balance N2 and a gas hourly space velocity of 4000 ml / g-h. A C3H7OH conversion of 88% and a CH3OH conversion of 54% were achieved. The isobutanol yield was 257 g / kg-h. Apparently, propanol was converted to isobutanol by reacting with methanol.

[0073] As used herein, the term "zone" refers to an area that includes one or more equipment items. A zone can include one or more sub-zones. Equipment items can include, for example, one or more reactors or reactor vessels, heaters, exchangers, pipes, pumps, compressors, and controllers. In addition, equipment items such as reactors, dryers, or vessels can include one or more zones or sub-zones.

[0074] As used herein, the term "about" means within 10%, or within 5%, or within 1% of a value.

[0075] Although at least one exemplary embodiment has been presented in the foregoing detailed description of the present invention, it should be understood that there are numerous variations. It should also be understood that the one or more exemplary embodiments are merely examples and are not intended to limit the scope, application, or configuration of the present invention in any way. Instead, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiments of the present invention. It should be understood that various changes can be made to the functions and arrangements of the elements described in the exemplary embodiments without departing from the scope of the present invention set forth in the appended claims.

Claims

1. A method for producing isobutanol, comprising: reacting ethanol with syngas in a first reaction zone in the presence of a multiphase catalyst under first reaction conditions to produce a first reaction mixture comprising methanol and propanol; wherein the multiphase catalyst comprises a catalyst based on K2O / CuZnAlO x or K2O / CuZnCrO x ; and wherein the first reaction conditions include at least one of the following: a temperature in the range of 200 °C to 500 °C; a pressure in the range of 0.1 MPa to 30 MPa; 0.1 mol% to 50 mol% ethanol and a balance of syngas having a ratio of H2 to CO in the range of 5:1 to 1:5; or a gas hourly space velocity in the range of 100 to 500000 liters of gas per kilogram of catalyst per hour (L / kg-h); separating the first reaction mixture into at least a methanol stream comprising methanol, an ethanol stream comprising ethanol, and a propanol stream comprising propanol; introducing the methanol stream and the propanol stream into a second reaction zone; and reacting methanol and propanol in the second reaction zone in the presence of a second catalyst under second reaction conditions to produce a second reaction mixture comprising isobutanol; wherein the second catalyst comprises at least one element from Group IA, IIA, IIIA, IVA, VA, IV, IB, IIB, VIB, VIIB, or VIIIB of the periodic table and combinations thereof; and wherein the second reaction conditions include at least one of the following: a temperature in the range of 100 °C to 500 °C; a pressure in the range of 0.1 MPa to 15 MPa; 0.1 mol% to 99 mol% methanol and 0.1 mol% to 99 mol% propanol; or a gas hourly space velocity in the range of 100 to 300000 liters of gas per kilogram of catalyst per hour (L / kg-h).

2. The method according to claim 1, wherein the second catalyst comprises at least one element from Groups IA and IIA of the periodic table, Al, Cu, Zn, Cr, Sr, and combinations thereof.

3. The method according to any one of claims 1 to 2, wherein the second catalyst comprises at least one of the following: MgO, MgO - Al2O3, CuO - MgO - Al2O3, Mg - PO4, Ca - PO4, Sr - PO4, alkali metal oxide-doped zeolites, and combinations thereof.

4. The method according to any one of claims 1 to 2, wherein separating the first reaction mixture into at least the methanol stream, the ethanol stream, and the propanol stream comprises: separating the first reaction mixture into a top gas stream and a liquid bottom stream comprising at least methanol, ethanol, and propanol in a gas-liquid separation zone; separating the liquid bottom stream into at least the methanol stream, the ethanol stream, the propanol stream, an isobutanol stream comprising isobutanol, and a n-butanol stream comprising n-butanol in a liquid separation zone.

5. The method according to claim 4, further comprising: separating the top gas stream into a first gas stream comprising CO2 and light hydrocarbons and a recycle syngas stream comprising CO and H2; and recycling the recycle syngas stream to the first reaction zone.

6. The method according to claim 4, wherein separating the bottom liquid stream comprises using an adsorption process or a distillation process.

7. The method according to claim 4, wherein the second reaction mixture further comprises unreacted methanol and unreacted propanol, and further comprises: Recycling the second reaction mixture to the liquid separation zone.

8. The method according to claim 4, wherein the second reaction mixture further comprises unreacted methanol and unreacted propanol, and further comprises: Separating the second reaction mixture in a second liquid separation zone into an unreacted methanol stream comprising unreacted methanol, an unreacted propanol stream comprising unreacted propanol, a second isobutanol stream comprising isobutanol, and a second n-butanol stream comprising n-butanol; and Optionally combining the isobutanol stream with the second isobutanol stream.

9. The method according to claim 8, further comprising: Recycling the unreacted methanol stream to the first reaction zone; and Recycling the unreacted propanol stream to the second reaction zone.

10. The method according to any one of claims 1 to 2, further comprising: Recycling the ethanol stream to the first reaction zone.

11. A method for producing isobutanol, comprising: Reacting ethanol with syngas in a first reaction zone in the presence of a multiphase catalyst under first reaction conditions to produce a first reaction mixture comprising methanol and propanol; wherein the multiphase catalyst comprises a catalyst based on K2O / CuZnAlO x or K2O / CuZnCrO x ; and Wherein the first reaction conditions include at least one of the following: a temperature in the range of 200 °C to 500 °C; a pressure in the range of 0.1 MPa to 30 MPa; 0.1 mol% to 50 mol% ethanol and a balance of syngas having a ratio of H2 to CO in the range of 5:1 to 1:5; or a gas hourly space velocity in the range of 100 to 500,000 liters of gas per kilogram of catalyst per hour (L / kg-h); Separating the first reaction mixture into a top gas stream and a bottom liquid stream comprising at least methanol, ethanol, propanol, isobutanol, and n-butanol; Separating the bottom liquid stream in a liquid separation zone into at least a methanol stream comprising methanol, an ethanol stream comprising ethanol, a propanol stream comprising propanol, an isobutanol stream comprising isobutanol, and an n-butanol stream comprising n-butanol; Introducing at least a portion of the methanol stream and the propanol stream into a second reaction zone; Reacting methanol and propanol in the second reaction zone in the presence of a second catalyst under second reaction conditions to produce a second reaction mixture comprising isobutanol; Wherein the second catalyst comprises at least one element from Group IA, IIA, IIIA, IVA, VA, IV, IB, IIB, VIB, VIIB, or VIIIB of the periodic table and combinations thereof; and Wherein the second reaction conditions include at least one of the following: a temperature in the range of 100 °C to 500 °C; a pressure in the range of 0.1 MPa to 15 MPa; 0.1 mol% to 99 mol% methanol and 0.1 mol% to 99 mol% propanol; or a gas hourly space velocity in the range of 100 to 300,000 liters of gas per kilogram of catalyst per hour (L / kg-h).

12. The method according to claim 11, further comprising: Recycling the second reaction mixture to the liquid separation zone; And Optionally at least one of the following: Recycling the ethanol stream to the first reaction zone; And Recycling a second portion of the methanol stream to the first reaction zone.

13. The method according to claim 11, further comprising: Separating the second reaction mixture in a second liquid separation zone into an unreacted methanol stream containing unreacted methanol, an unreacted propanol stream containing unreacted propanol, a second isobutanol stream containing isobutanol, and a second n-butanol stream containing n-butanol.

14. The method according to claim 11, further comprising: Separating the top gas stream into a first gas stream containing CO2 and light hydrocarbons and a recycle synthesis gas stream containing CO and H2; and Recycling the recycle synthesis gas stream to the first reaction zone.

15. The method according to claim 11, Wherein the second catalyst comprises at least one element selected from Groups IA and IIA of the Periodic Table, Al, Cu, Zn, Cr, Sr, and combinations thereof.

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