A method and system for producing higher carbon alcohols

Abstract

This invention relates to the field of higher alcohol preparation technology and discloses a method and system for producing higher alcohols. Under the action of a catalyst, a mixed liquid of hydrocarbons, aldehydes, alcohols and water is produced. After hydrogenation, the aldehydes are converted into alcohols. After processing through a splitting tower, mixed higher alcohols are obtained. Then, a first separation process is performed to obtain mixed higher alcohols with a yield of ≥98%. Finally, a second distillation process is performed to obtain single higher alcohols with a purity of >99%.

Description

Technical Field

[0001] This invention relates to the field of higher alcohol preparation technology, and specifically to a method and system for producing higher alcohols. Background Technology

[0002] Higher alcohols generally refer to alcohol compounds containing six or more carbon atoms. They can be classified according to their uses into plasticizer alcohols (C6-C11), detergent alcohols (C12-C20), and higher alkanols (C21-C34), etc. Plasticizer alcohols are one of the raw materials for plasticizers, which have excellent plasticizing properties and can be used as plasticizers for polyvinyl chloride, nitrocellulose, polystyrene, ethyl cellulose, nitrile rubber, etc., improving the processability and usability of soft plastic products such as artificial leather and wallpaper. Detergent alcohols are one of the raw materials for detergents and surfactants. Detergents made from higher alcohols have a wide washing range, strong detergency, are easily biodegradable, and produce less pollution, and can be formulated into various high-performance surfactants. Higher alkanols with longer carbon chains have important physiological activities and are widely used in functional foods, nutritional preparations, pharmaceuticals, cosmetics, and high-grade animal feed.

[0003] Existing technologies for producing higher alcohols mainly include the natural oil hydrogenation method, the higher olefin hydroformylation method, and the hydrocarbon aluminum method. The natural oil hydrogenation method uses natural oils such as coconut oil, palm oil, and cashew nut shell oil as raw materials, producing higher alcohols through high-pressure hydrogenation. Higher alcohols produced using this method are of good quality and biocompatibility; however, the natural oil raw materials are mainly produced in tropical Southeast Asian countries, making large-scale production difficult. The higher olefin hydroformylation method uses long-chain α-olefins separated from petrochemical and coal-to-oil products as raw materials. Under the action of a cobalt carbonyl catalyst, hydroformylation produces long-chain higher aldehydes, which are then simply hydrogenated to obtain long-chain higher alcohols. Although this method can eliminate dependence on natural oil raw materials, the quality of the long-chain higher alcohols is relatively poor, and the proportion of n-alcohols and iso-alcohols in the product is low, requiring the separation of iso-alcohol byproducts. Furthermore, it has relatively high energy consumption and cost. The hydrocarbon-based aluminum method is a chemical synthesis method for producing long-chain higher alcohols using petroleum derivatives as raw materials. It uses triethylaluminum catalysts, and ethylene feedstock undergoes triethylaluminum chain growth reactions and processes such as oxidation, hydrolysis, and distillation to produce higher alcohols. This method has disadvantages such as high consumption of triethylaluminum catalyst, high cost, poor production flexibility, long process flow, and complex technology. In addition, hydrocarbon-based aluminum is highly flammable and explosive, posing a great safety hazard.

[0004] Therefore, how to adjust and improve the production methods of higher alcohols to obtain higher alcohols with high yield and high purity is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention provides a method for producing higher alcohols to solve the problem of poor quality of higher alcohols in the prior art.

[0006] In a first aspect, the present invention provides a method for producing higher alcohols, comprising the following steps:

[0007] (1) Under the action of a catalyst, CO reacts with H2 to produce a mixture of aldehydes, alcohols and hydrocarbons;

[0008] (2) The aldehyde-alcohol-hydrocarbon mixture is subjected to a first distillation process to obtain the overhead liquid;

[0009] (3) The liquid at the top of the column is hydrogenated, and the hydrogenated product is separated by a cutting column to obtain light fraction, middle fraction and heavy fraction; wherein the cutting temperature of the light fraction and the middle fraction is T1, and the cutting temperature of the middle fraction and the heavy fraction is T2, where T2 > T1;

[0010] (4) The middle fraction is subjected to a first separation process to obtain a mixture of higher alcohols and a mixture of hydrocarbons;

[0011] (5) The mixed higher alcohols are subjected to a second distillation process to obtain single-component higher alcohols.

[0012] In some alternative implementations, step (2) further includes obtaining the bottom liquid after the first distillation process.

[0013] In some optional embodiments, the bottom liquid, the light fraction, the heavy fraction and the mixed hydrocarbons are further subjected to hydrogenation saturation treatment, followed by dehydration to obtain straight-chain alkane oil.

[0014] In some alternative implementations, step (1) further includes reacting CO with H2 to obtain residual gas.

[0015] In some optional embodiments, the residual gas is further subjected to washing, heat exchange, and a first separation treatment; the liquid after the first separation treatment is separated by a coalescer to obtain low-carbon hydrocarbon light oil and synthetic water respectively; the low-carbon hydrocarbon light oil is subjected to the hydrogenation treatment; the gas after the first separation treatment is compressed, a portion of which is returned to the reactor in step (1) as the main circulating gas, and the remaining portion is subjected to low-temperature oil washing treatment to obtain liquefied gas; the gas after low-temperature oil washing is subjected to pressure swing adsorption to obtain fuel gas, hydrogen and carbon monoxide, and the hydrogen and carbon monoxide are returned to the reactor in step (1) as external circulating gas.

[0016] In some optional embodiments, the synthesis water is further subjected to a third distillation process, and the resulting overhead liquid is subjected to a low-carbon aldehyde hydrogenation process and a low-carbon alcohol separation process to obtain C1-C5 alcohol and C6 alcohol, wherein the C6 alcohol is returned to the second distillation process in step (5).

[0017] In some alternative embodiments, the second distillation process includes precision distillation and / or extractive distillation.

[0018] In some alternative embodiments, the hydrogen-to-carbon ratio of the mixture of CO, H2, the internal circulating gas, and the external circulating gas is 2.0-2.8.

[0019] In some alternative embodiments, the reaction temperature is 170°C-300°C, the reaction pressure is 2.0 MPaG-6.0 MPaG, and the space velocity is 1800 h⁻¹. -1 -6000h -1 .

[0020] In some alternative embodiments, the catalyst for the hydrogenation treatment includes a nickel-based catalyst.

[0021] In some alternative implementations, 115℃<T1≤140℃, 230℃≤T2≤450℃.

[0022] In a second aspect, the present invention provides a system for the production method described in the first aspect, comprising:

[0023] The first distillation unit has its inlet connected to the liquid outlet of the reactor; the first distillation unit includes a top liquid outlet and a bottom liquid outlet;

[0024] The hydrogenation unit has its inlet connected to the overhead liquid outlet of the first distillation unit.

[0025] A cutting column, the inlet of which is connected to the outlet of the hydrogenation unit; the cutting column includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet;

[0026] The first separation unit has its inlet connected to the middle fraction outlet of the cutting tower; the first separation unit includes a mixed alcohol outlet and a mixed hydrocarbon outlet;

[0027] The inlet of the second distillation unit is connected to the mixed alcohol outlet of the first separation unit.

[0028] In some alternative embodiments, the first distillation unit further includes a bottom liquid outlet.

[0029] In some alternative embodiments, a hydrogenation saturation device is also included, the inlet of which is connected to the bottom liquid outlet of the first distillation unit, the light fraction outlet and the heavy fraction outlet of the cutting column, and the mixed hydrocarbon outlet of the first separation unit, respectively.

[0030] In some alternative embodiments, a washing device is also included, the inlet of which is connected to the gas outlet of the reactor;

[0031] A heat exchange device, the inlet of which is connected to the outlet of the washing device;

[0032] The second separation device has its inlet connected to the outlet of the heat exchange device; the separation device includes a liquid outlet and a gas outlet.

[0033] A coalescer, the inlet of which is connected to the liquid outlet of the second separation unit; the coalescer includes a low-carbon hydrocarbon light oil outlet and a synthetic water outlet, the low-carbon hydrocarbon light oil outlet being connected to the inlet of the hydrogenation unit;

[0034] A compression device, the inlet of which is connected to the gas outlet of the second separation device, and the outlet of which is connected to the gas inlet of the reactor;

[0035] A cryogenic oil washing device, the inlet of which is connected to the outlet of the compression device; the cryogenic oil washing device includes a gas outlet and a liquefied gas outlet;

[0036] The pressure swing adsorption device has its inlet connected to the gas outlet of the cryogenic oil washing device; the pressure swing adsorption device includes a fuel gas outlet, a hydrogen outlet, and a carbon monoxide outlet, and the hydrogen outlet and the carbon monoxide outlet are connected to the gas inlet of the reactor.

[0037] In some alternative embodiments, a third distillation unit is also included, the inlet of which is connected to the synthesis water outlet of the coalescer; the third distillation unit includes an overhead liquid outlet and a bottom liquid outlet;

[0038] The inlet of the low-carbon aldehyde hydrogenation unit is connected to the overhead liquid outlet of the third distillation unit.

[0039] The inlet of the low-carbon alcohol separation unit is connected to the outlet of the low-carbon aldehyde hydrogenation unit.

[0040] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0041] 1. The method for producing higher alcohols provided by the present invention includes the following steps: under the action of a catalyst, CO and H2 react to obtain an aldehyde-alcohol-hydrocarbon mixture; the aldehyde-alcohol-hydrocarbon mixture is subjected to a first distillation treatment to obtain a top liquid; the top liquid is subjected to hydrogenation treatment, and the hydrogenation product is separated by a cutting column to obtain a light fraction, a middle fraction, and a heavy fraction; wherein the cutting temperature of the light fraction and the middle fraction is T1, and the cutting temperature of the middle fraction and the heavy fraction is T2, where T2 > T1; the middle fraction is subjected to a first separation treatment to obtain a mixed higher alcohol and a mixed hydrocarbon; the mixed higher alcohol is subjected to a second distillation treatment to obtain a single-component higher alcohol. This invention produces a mixed liquid of hydrocarbons, aldehydes, alcohols and water under the action of a catalyst. After hydrogenation, the aldehydes are converted into alcohols. Then, a light oil cutting process is used to obtain a mixed higher alcohol with a boiling point of T1-T2. A first separation process is then used to obtain a mixed higher alcohol with a yield of ≥98%. Finally, a second distillation process is used to obtain a single higher alcohol with a purity of >99%.

[0042] The present invention has a short process flow, low investment, low energy consumption, and near-zero CO2 emissions, and has very good prospects for industrialization. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is the high-carbon alcohol production system in this embodiment of the invention;

[0045] Explanation of reference numerals in the attached figures:

[0046] Reactor 01, Washing device 02, Heat exchanger 03, Second separation device 04, Coalescer 05, Compression device 06, First distillation device 07, Low-temperature oil washing device 08, Pressure swing adsorption device 09, Hydrogenation device 10, Cutting tower 11, First separation device 12, Second distillation device 13, Hydrogenation saturation device 14, Third distillation device 15, Low-carbon aldehyde hydrogenation device 16, Low-carbon alcohol separation device 17. Detailed Implementation

[0047] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0048] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0049] To address the problems existing in the aforementioned related technologies, according to a first aspect of the present invention, a method for producing higher alcohols is provided, comprising the following steps:

[0050] (1) Under the action of a catalyst, CO reacts with H2 to produce a mixture of aldehydes, alcohols and hydrocarbons;

[0051] (2) The aldehyde-alcohol-hydrocarbon mixture is subjected to a first distillation process to obtain the overhead liquid;

[0052] (3) The liquid at the top of the column is hydrogenated, and the hydrogenated product is separated by a cutting column to obtain light fraction, middle fraction and heavy fraction; wherein the cutting temperature of the light fraction and the middle fraction is T1, and the cutting temperature of the middle fraction and the heavy fraction is T2, where T2 > T1;

[0053] (4) The middle fraction is subjected to a first separation process to obtain a mixture of higher alcohols and a mixture of hydrocarbons;

[0054] (5) The mixed higher alcohols are subjected to a second distillation process to obtain single-component higher alcohols.

[0055] It should be noted that the raw material of this invention is syngas, the main components of which include CO and H2.

[0056] It should be noted that the middle fraction includes a mixture of mixed higher alcohols and mixed hydrocarbons with boiling points T1 to T2;

[0057] It should be noted that the liquid at the top of the column is hydrogenated to convert the aldehydes into alcohols. Then, after separation by a splitting column, alcohols within the target carbon number range and hydrocarbons with corresponding boiling points are separated. The first separation process is then performed to separate the mixed higher alcohols and mixed hydrocarbons. The recovery rate of the mixed higher alcohols is >98%. The mixed higher alcohols are then subjected to a second distillation process to obtain single-component higher alcohols with a purity >99%.

[0058] It should be noted that the cutting tower separates light oil into different fractions according to the boiling point range through distillation. In this invention, 115℃<T1≤140℃, 230℃≤T2≤450℃.

[0059] It should be noted that in the hydrogenation process, liquid-phase hydrogenation is used, and the hydrogenation catalyst includes at least one of the nickel-based catalysts. The hydrogenation catalyst has high selectivity, only hydrogenating aldehydes to convert them into alcohols, and the alcohols cannot be further hydrogenated.

[0060] The preparation method of the nickel-based catalyst in this invention, referring to Example 1 of Chinese Patent Document CN111215107A, includes the following steps: Under reaction conditions of 100°C, 95g Ni(NO3)2·6H2O, 17.8g Mg(NO3)2·6H2O, 0.74g Co(NO3)2·6H2O, and 2.98g Ca(NO3)2·4H2O are dissolved in 0.5L of boiling water. Under reaction conditions of 100°C, in a reactor equipped with a stirrer, 75g Na2CO3 is dissolved in 0.7L of boiling water. Under rapid stirring, a solution containing Ni(NO3)2-Mg(NO3)2-Co(NO3)2-Ca(NO3)2 is poured into the Na2CO3 solution at a rate of 5 mL / s. After pouring in the Ni-Mg-Co-Ca solution, 11.5g of ammonia-treated diatomaceous earth powder is quickly added, and the reaction mixture is stirred for 5 minutes. The filter cake was then filtered, and washed with hot water at 80°C. The conductivity of the outflowing wash water was measured, and washing was stopped when the conductivity decreased to 1800 μs. Under reaction conditions of 50°C, the filter cake was placed in 0.3 L of 0.25 wt% NaOH solution, and the reaction suspension was stirred for 3 hours. The filter cake was then filtered, and dried in a drying oven at 60°C for 5 hours, 80°C for 5 hours, and 120°C for 10 hours until constant weight was achieved. The catalyst was then prepared through granulation and tableting processes.

[0061] It should be noted that in the first separation process, aromatic hydrocarbons, hydrocarbons, and alcohols are used as solvents, preferably aromatic hydrocarbons; wherein, aromatic hydrocarbons include at least one of benzene, toluene, and xylene; hydrocarbons include at least one of pentane, hexane, and heptane; and alcohols include at least one of ethylene glycol, isopropanol, and butanol.

[0062] In some alternative implementations, the second distillation process includes precision distillation and / or extractive distillation, preferably precision distillation, combined with a heat pump process to shorten the process and reduce energy consumption.

[0063] In some optional embodiments, step (2) after the first distillation process includes obtaining a bottom liquid, and then subjecting the bottom liquid, the light fraction, the heavy fraction and the mixed hydrocarbons to a hydrogenation saturation treatment step, and after dehydration, obtaining straight-chain alkane oil.

[0064] It should be noted that the bottom liquid, light fraction, heavy fraction and the mixed hydrocarbons are subjected to a hydrogenation saturation treatment step to convert the aldehydes and alcohols therein into hydrocarbons and water. After dehydration, straight-chain alkane oil is obtained, which can be further separated or used directly as a product.

[0065] In some optional embodiments, in step (1), the reaction of CO and H2 further includes obtaining residual gas, which is then washed, heat-exchanged, and subjected to a second separation treatment. The liquid after the second separation treatment is separated by a coalescer to obtain low-carbon hydrocarbon light oil and synthetic water, respectively. The low-carbon hydrocarbon light oil is subjected to the hydrogenation treatment. The gas after the second separation treatment is compressed, and a portion of it is returned to the reactor in step (1) as the main circulating gas. The remaining portion is subjected to low-temperature oil washing treatment to obtain liquefied gas. The gas after low-temperature oil washing is subjected to pressure swing adsorption to obtain fuel gas, hydrogen and carbon monoxide. The hydrogen and carbon monoxide are returned to the reactor in step (1) as external circulating gas.

[0066] It should be noted that the slurry bed reactor is equipped with an internal filter to trap the cobalt-based catalyst inside the reactor. The liquid product generated by the reaction flows out of the reactor through the internal filter. The material inside the reactor exists in a gas-liquid-solid three-phase state. The reaction conditions are: temperature 170℃-300℃, pressure 2.0MPaG-6.0MPaG, and space velocity 1800h⁻¹. -1 -6000h -1 In the reaction, syngas is converted into hydrocarbons, alcohols, aldehydes, and water. Alcohols and aldehydes account for more than 50 wt% of the total organic matter. Unconverted syngas and the C1-C4 light hydrocarbons generated in the reaction exit from the top of the reactor. The gas is washed by a scrubbing device to remove solid catalyst particles entrained in the gas. The catalyst particles are returned to the reactor. The gas at the top of the scrubbing device is cooled to 40°C through heat exchange, and low-carbon hydrocarbon light oil and syngas water are precipitated. These are separated by a separator. The low-carbon hydrocarbon light oil and syngas water are separated by a coalescer to achieve oil-water separation. The gas phase at the top of the separator enters the gas compressor. After being pressurized, a portion is returned to the reactor as recirculated gas to maintain the reactor space velocity. The remaining portion enters the low-temperature oil washing treatment to recover the C2-C4 components in the gas and obtain liquefied petroleum gas (LPG). The gas collected from the low-temperature oil washing unit enters the pressure swing adsorption (PSA) unit to separate high-purity hydrogen, CO, and fuel gas. The hydrogen and CO are returned to the reactor as recirculated gas, effectively adjusting the hydrogen-carbon ratio at the inlet of the slurry bed reactor and maintaining the balance of C1-C4 hydrocarbons in the recirculated gas.

[0067] It should be noted that low-temperature oil washing treatment is carried out under low temperature (-40℃ to 10℃) and pressurized (1MPa-5MPa) conditions, using solvent oil (wash oil) to selectively absorb heavy hydrocarbons (carbon atoms ≥3) and impurities in the gas. Subsequently, solvent regeneration and heavy hydrocarbon recovery are achieved by heating or depressurization.

[0068] The slurry bed reactor produces a low amount of CO2 during the reaction process, with the CO2 content in the circulating gas being less than 0.1%. A decarbonization unit can be set up before the circulating gas enters the low-temperature oil washing unit. Preferably, no decarbonization unit is set up to shorten the process and reduce investment.

[0069] In some optional embodiments, after the synthetic water undergoes a third distillation process, the resulting overhead liquid is subjected to a low-carbon aldehyde hydrogenation process and a low-carbon alcohol separation process to obtain C1-C5 alcohols and C6 alcohols, with the C6 alcohols being returned to the second distillation process.

[0070] It should be noted that the synthetic water contains aldehydes and C1-C6 alcohols. After the third distillation process, the aldehydes and alcohols are separated from the water. Then, the low-carbon aldehydes are hydrogenated to convert them into alcohols. The low-carbon alcohols are then separated to separate the C1-C5 low-carbon alcohols from the C6 high-carbon alcohols. The C6 alcohols are returned to the second distillation process, and the C1-C5 low-carbon alcohols are used as the product.

[0071] This invention describes a one-step process for producing higher alcohols using syngas in the presence of a cobalt-based catalyst, and separates C6-C11 individual higher alcohols, straight-chain alkane oils, liquefied petroleum gas (LPG), and fuel gas.

[0072] It should be noted that the particle size of the cobalt-based catalyst of the present invention is 20μm-180μm. The preparation method of the cobalt-based catalyst, referring to Example 1 of Chinese Patent Document CN112892543A, includes the following steps: 4.94g of cobalt nitrate hexahydrate, 0.91g of zinc nitrate hexahydrate, and 0.23g of manganese acetate tetrahydrate are dissolved in 10g of water to prepare an impregnation solution. 8.73g of activated carbon support is impregnated with this impregnation solution at room temperature (298K) and then air-dried for about 10 hours until there is no free-flowing moisture on the catalyst surface. It is then dried in a 313K oven for 24 hours, removed, and calcined in argon atmosphere at a gradually increasing temperature to 573K for 20 hours to obtain dry-based catalyst precursor A. Then, 0.074g of sodium nitrate is dissolved in 10g of water to prepare an impregnation solution. The dry-based catalyst precursor A was impregnated with the impregnation solution at room temperature (298 K) and then air-dried for about 10 hours until no free-flowing moisture remained on the catalyst surface. It was then dried in a 313 K oven for 24 hours. After removal, it was calcined in argon atmosphere at a gradually increasing temperature to 573 K for 20 hours to obtain the dry-based catalyst precursor B. The dry-based catalyst precursor B was then placed into a fixed-bed reactor with a diameter of 9 mm, with a packing volume of 2 mL and a space velocity of 2000 h⁻¹. -1 The catalyst was gradually heated to 673K ​​in hydrogen for 15 hours for reduction, and then cooled to 423K.

[0073] In a second aspect, the present invention provides a system for the production method described in the first aspect, comprising:

[0074] The first distillation unit has its inlet connected to the liquid outlet of the reactor; the first distillation unit includes a top liquid outlet and a bottom liquid outlet;

[0075] The hydrogenation unit has its inlet connected to the overhead liquid outlet of the first distillation unit.

[0076] A cutting column, the inlet of which is connected to the outlet of the hydrogenation unit; the cutting column includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet;

[0077] The first separation unit has its inlet connected to the middle fraction outlet of the cutting tower; the first separation unit includes a mixed alcohol outlet and a mixed hydrocarbon outlet;

[0078] The inlet of the second distillation unit is connected to the mixed alcohol outlet of the first separation unit.

[0079] In some alternative embodiments, a hydrogenation saturation device is also included, the inlet of which is connected to the bottom liquid outlet of the first distillation unit, the light fraction outlet and the heavy fraction outlet of the cutting column, and the mixed hydrocarbon outlet of the first separation unit, respectively.

[0080] In some alternative embodiments, a scrubbing device is also included, the inlet of which is connected to the gas outlet of the reactor.

[0081] The heat exchanger has its inlet connected to the outlet of the washing device.

[0082] The second separation device has its inlet connected to the outlet of the heat exchange device; the second separation device includes a liquid outlet and a gas outlet.

[0083] A coalescer, the inlet of which is connected to the liquid outlet of the second separation unit; the coalescer includes a low-carbon hydrocarbon light oil outlet and a synthetic water outlet, the low-carbon hydrocarbon light oil outlet being connected to the inlet of the hydrogenation unit;

[0084] A compression device, the inlet of which is connected to the gas outlet of the second separation device, and the outlet of which is connected to the gas inlet of the reactor;

[0085] A cryogenic oil washing device, the inlet of which is connected to the outlet of the compression device; the cryogenic oil washing device includes a gas outlet and a liquefied gas outlet;

[0086] The pressure swing adsorption device has its inlet connected to the gas outlet of the cryogenic oil washing device; the pressure swing adsorption device includes a fuel gas outlet, a hydrogen outlet, and a carbon monoxide outlet, and the hydrogen outlet and the carbon monoxide outlet are connected to the gas inlet of the reactor.

[0087] In some alternative embodiments, a third distillation unit is also included, the inlet of which is connected to the synthesis water outlet of the coalescer; the third distillation unit includes an overhead liquid outlet and a bottom liquid outlet;

[0088] The inlet of the low-carbon aldehyde hydrogenation unit is connected to the overhead liquid outlet of the third distillation unit.

[0089] The inlet of the low-carbon alcohol separation unit is connected to the outlet of the low-carbon aldehyde hydrogenation unit.

[0090] It should be noted that the second distillation unit includes multiple distillation columns connected in series.

[0091] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0092] Example 1

[0093] like Figure 1 As shown, this embodiment provides a production system for higher alcohols, including a reactor 01, a washing device 02, a heat exchange device 03, a second separation device 04, a coalescer 05, a compression device 06, a first distillation device 07, a low-temperature oil washing device 08, a pressure swing adsorption device 09, a hydrogenation device 10, a cutting tower 11, a first separation device 12, a second distillation device 13, a hydrogenation saturation device 14, a third distillation device 15, a low-carbon aldehyde hydrogenation device 16, and a low-carbon alcohol separation device 17; specifically:

[0094] The washing device 02 has its inlet connected to the gas outlet of the reactor 01, and its solid outlet connected to the catalyst inlet of the reactor 01.

[0095] The inlet of heat exchange device 03 is connected to the gas outlet of washing device 02;

[0096] The second separation device 04 has its inlet connected to the liquid outlet of the heat exchange device 03; the second separation device 04 includes a liquid outlet and a gas outlet.

[0097] The coalescer 05 has its inlet connected to the liquid outlet of the second separation unit 04; the coalescer 05 includes a low-carbon hydrocarbon light oil outlet and a synthetic water outlet, and the low-carbon hydrocarbon light oil outlet is connected to the inlet of the hydrogenation unit 10.

[0098] The inlet of the compression device 06 is connected to the gas outlet of the second separation device 04, and its outlet is connected to the gas inlet of the reactor 01.

[0099] The low-temperature oil washing device 08 has its inlet connected to the outlet of the compression device 06; the low-temperature oil washing device 08 includes a gas outlet and a liquefied gas outlet.

[0100] The pressure swing adsorption device 09 has its inlet connected to the gas outlet of the low-temperature oil washing device 08; the pressure swing adsorption device 09 includes a fuel gas outlet, a hydrogen outlet and a carbon monoxide outlet, and the hydrogen outlet and carbon monoxide outlet are connected to the gas inlet of the reactor 01.

[0101] The first distillation unit 07 has its inlet connected to the liquid outlet of the reactor 01; the first distillation unit 07 includes a top liquid outlet and a bottom liquid outlet.

[0102] The hydrogenation unit 10 has its inlet connected to the overhead liquid outlet of the first distillation unit 07;

[0103] The cutting tower 11 has its inlet connected to the outlet of the hydrogenation unit 10. The cutting tower 11 includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet.

[0104] The first separation unit 12 has its inlet connected to the middle fraction outlet of the cutting tower 11; the first separation unit 12 includes a mixed alcohol outlet and a mixed hydrocarbon outlet;

[0105] The inlet of the second distillation unit 13 is connected to the mixed alcohol outlet of the first separation unit 12;

[0106] The hydrogenation saturation unit 14 has its inlet connected to the bottom liquid outlet of the first distillation unit 07, the light fraction outlet and the heavy fraction outlet of the cutting column 11, and the mixed hydrocarbon outlet of the first separation unit 12, respectively.

[0107] The third distillation unit 15 has its inlet connected to the synthesis water outlet of the coalescer 05; the third distillation unit 15 includes a top liquid outlet and a bottom liquid outlet.

[0108] The inlet of the low-carbon aldehyde hydrogenation unit 16 is connected to the top liquid outlet of the third distillation unit 15.

[0109] The inlet of the low-carbon alcohol separation unit 17 is connected to the outlet of the low-carbon aldehyde hydrogenation unit 16.

[0110] Example 2

[0111] Using the system of Example 1, this example provides a method for producing higher alcohols, comprising the following steps:

[0112] (1) The synthesis gas (hydrogen-to-carbon molar ratio of 2.05) and the circulating gas are combined and fed into a slurry bed reactor containing a cobalt-based catalyst with a particle size of 20μm-180μm. The volume ratio of circulating gas to synthesis gas is 20, the reaction temperature is 230℃, the reaction pressure is 3.0MPaG, and the space velocity is 2600h. -1 After the reaction is complete, a mixture of aldehydes, alcohols, and hydrocarbons and residual gas are obtained.

[0113] (2) The residual gas, including unconverted syngas and C1-C4 light hydrocarbons generated in the reaction, exits from the top of the reactor and enters a scrubbing tower to wash away solid catalyst particles entrained in the gas before returning it to the reactor. The gas at the top of the scrubbing tower is cooled to 40°C through heat exchange, and low-carbon hydrocarbon light oil and synthetic water are precipitated. After separation in a separator, the low-carbon hydrocarbon light oil and synthetic water are separated by a coalescing device to achieve oil-water separation, yielding low-carbon hydrocarbon light oil and synthetic water. The gas phase at the top of the separator enters the compressor, and after pressurization, a portion is returned to the reactor as the main circulating gas. The reactor space velocity is maintained by the reactor; the remaining gas enters the low-temperature oil washing unit at a temperature of -30℃ and a pressure of 2.0-4.0MPa. The solvent oil is light oil, which recovers the C2-C4 components (containing a small amount of C2, mainly C3-C4 components) from the gas to obtain liquefied gas; the gas collected from the low-temperature oil washing unit enters the pressure swing adsorption (PSA) unit 3 to separate high-purity H2, CO and fuel gas. H2 and CO are returned to the reactor as external circulation gas, and the hydrogen-to-carbon ratio of the feed at the slurry bed inlet is controlled at 2.12.

[0114] (3) An internal filter is provided inside the slurry bed reactor. The internal filter keeps the catalyst inside the reactor. The aldehyde-alcohol-hydrocarbon mixture generated by the reaction flows out of the reactor through the internal filter and is separated by the first distillation column to obtain the top liquid and bottom liquid.

[0115] (4) The low-carbon hydrocarbon light oil and the overhead liquid are combined and then fed into the light oil hydrogenation unit. The hydrogenation catalyst is a nickel-based catalyst, which converts the aldehydes into alcohols. Then, the light oil enters the light oil cutting unit at a temperature range of 140℃-245℃ to obtain light, middle, and heavy fractions. The light fraction includes mixed alcohols of C1-C5 and mixed hydrocarbons of C5-C8, the heavy fraction includes mixed alcohols of C12-C22 and mixed hydrocarbons of C14-C24, and the middle fraction includes mixed alcohols of C6-C11 and mixed hydrocarbons of C9-C13. The middle fraction is then fed into the light oil cutting unit. The mixture is introduced into an adsorption separation unit using toluene as the solvent to separate C6-C11 mixed alcohols and C8-C14 mixed hydrocarbons, yielding C9-C14 mixed hydrocarbons and C6-C11 mixed alcohols respectively. The recovery rate of the mixed alcohols is 98%. The mixed alcohols are then introduced into a second distillation unit, where precision distillation technology is used to separate individual higher alcohols of C6, C7, C8, C9, C10, and C11, with a product purity greater than 99%. C6-C11 higher alcohols account for 28% of the product. The products include higher alcohols, lower alcohols, liquefied petroleum gas, fuel gas, and straight-chain alkane oils.

[0116] (5) Combine the bottom liquid, light fraction, heavy fraction and C8-C14 mixed hydrocarbons obtained from the adsorption separation unit and enter the hydrogenation saturation unit to convert the aldehydes and alcohols in it into hydrocarbons and water. After dehydration, straight-chain alkane oil is obtained.

[0117] (6) The synthetic water obtained from the coalescing unit contains aldehydes and C1-C6 alcohols. It is first fed into the third distillation column for separation to separate the aldehydes and alcohols from the water. The top liquid of the column enters the low-carbon aldehyde hydrogenation unit to convert the aldehydes into alcohols. Then it enters the low-carbon alcohol separation unit to separate the C1-C5 low-carbon alcohols from C6. The C6 is returned to the second distillation to obtain C1-C5 low-carbon alcohols, which account for 6% of the product.

[0118] Example 3

[0119] This embodiment provides a method for producing higher alcohols, which is basically the same as the steps in Embodiment 1. The only difference is that in step (4), T1 in the cutting tower is controlled to be 150°C and T2 to be 360°C, to obtain light fraction, middle fraction and heavy fraction; wherein, the light fraction includes mixed alcohols of C1-C5 and mixed hydrocarbons of C5-C8, the heavy fraction includes mixed alcohols of C19-C22 and mixed hydrocarbons of C22-C24, the middle fraction includes mixed alcohols of C6-C18 and mixed hydrocarbons of C9-C21, and the C5-C18 higher alcohols account for 42% of the product.

[0120] Comparative Example 1

[0121] This comparative example provides a method for producing higher alcohols, which is basically the same as the steps in Example 1, except that the light oil cutting step (4) is omitted, and higher alcohols cannot be produced.

[0122] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for producing higher alcohols, characterized in that, The steps include: (1) Under the action of a catalyst, CO reacts with H2 to produce a mixture of aldehydes, alcohols and hydrocarbons; (2) The aldehyde-alcohol-hydrocarbon mixture is subjected to a first distillation process to obtain the overhead liquid; (3) The overhead liquid of the column is hydrogenated, and the hydrogenated product is separated by a cutting column to obtain light fraction, middle fraction and heavy fraction; wherein the cutting temperature of the light fraction and the middle fraction is T1, the cutting temperature of the middle fraction and the heavy fraction is T2, T2>T1; 115℃<T1≤140℃, 230℃≤T2≤450℃; (4) The middle fraction is subjected to a first separation process to obtain a mixture of higher alcohols and a mixture of hydrocarbons; (5) The mixed higher alcohols are subjected to a second distillation process to obtain single-component higher alcohols.

2. The method for producing higher alcohols according to claim 1, characterized in that, In step (2), after the first distillation process, the bottom liquid of the column is also obtained; It also includes hydrogenating and saturating the bottom liquid, the light fraction, the heavy fraction and the mixed hydrocarbons, and then dehydrating them to obtain straight-chain alkane oil.

3. The method for producing higher alcohols according to claim 1, characterized in that, In step (1), the reaction of CO with H2 also includes obtaining residual gas; The process also includes washing, heat exchange, and a second separation of the residual gas; the liquid after the second separation is separated by a coalescer to obtain low-carbon hydrocarbon light oil and synthetic water respectively; the low-carbon hydrocarbon light oil is subjected to the hydrogenation treatment; the gas after the second separation is compressed, a portion of which is returned to the reactor in step (1) as the main circulating gas, and the remaining portion is subjected to low-temperature oil washing to obtain liquefied gas; the gas after low-temperature oil washing is subjected to pressure swing adsorption to obtain fuel gas, hydrogen and carbon monoxide, and the hydrogen and carbon monoxide are returned to the reactor in step (1) as external circulating gas.

4. The method for producing higher alcohols according to claim 3, characterized in that, It also includes subjecting the synthetic water to a third distillation process, and then sequentially subjecting the resulting overhead liquid to low-carbon aldehyde hydrogenation and low-carbon alcohol separation processes to obtain C1-C5 alcohols and C6 alcohols, with the C6 alcohols being returned to the second distillation process in step (5).

5. The method for producing higher alcohols according to claim 1, characterized in that, The second distillation process includes precision distillation and / or extractive distillation.

6. The method for producing higher alcohols according to claim 3, characterized in that, The reaction was carried out at a temperature of 170℃-300℃, a pressure of 2.0 MPaG-6.0 MPaG, and a space velocity of 1800 h⁻¹. -1 -6000h -1 ; And / or, the catalyst for the hydrogenation treatment includes a nickel-based catalyst.

7. A system for the method of producing higher alcohols according to any one of claims 1-6, characterized in that, include: The first distillation unit has its inlet connected to the liquid outlet of the reactor; the first distillation unit includes an overhead liquid outlet. The hydrogenation unit has its inlet connected to the overhead liquid outlet of the first distillation unit. A cutting column, the inlet of which is connected to the outlet of the hydrogenation unit; the cutting column includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet; The first separation unit has its inlet connected to the middle fraction outlet of the cutting tower; the first separation unit includes a mixed alcohol outlet and a mixed hydrocarbon outlet; The inlet of the second distillation unit is connected to the mixed alcohol outlet of the first separation unit.

8. The production system for higher alcohols according to claim 7, characterized in that, The first distillation unit also includes a bottom liquid outlet; It also includes a hydrogenation saturation unit, the inlet of which is connected to the bottom liquid outlet of the first distillation unit, the light fraction outlet and the heavy fraction outlet of the cutting tower, and the mixed hydrocarbon outlet of the first separation unit, respectively.

9. The production system for higher alcohols according to claim 8, characterized in that, It also includes a washing device, the inlet of which is connected to the gas outlet of the reactor; A heat exchange device, the inlet of which is connected to the outlet of the washing device; The second separation device has its inlet connected to the outlet of the heat exchange device; the separation device includes a liquid outlet and a gas outlet. A coalescer, the inlet of which is connected to the liquid outlet of the second separation unit; the coalescer includes a low-carbon hydrocarbon light oil outlet and a synthetic water outlet, the low-carbon hydrocarbon light oil outlet being connected to the inlet of the hydrogenation unit; A compression device, the inlet of which is connected to the gas outlet of the second separation device, and the outlet of which is connected to the gas inlet of the reactor; A cryogenic oil washing device, the inlet of which is connected to the outlet of the compression device; the cryogenic oil washing device includes a gas outlet and a liquefied gas outlet; The pressure swing adsorption device has its inlet connected to the gas outlet of the cryogenic oil washing device; the pressure swing adsorption device includes a fuel gas outlet, a hydrogen outlet, and a carbon monoxide outlet, and the hydrogen outlet and the carbon monoxide outlet are connected to the gas inlet of the reactor.

10. The production system for higher alcohols according to claim 9, characterized in that, It also includes a third distillation unit, the inlet of which is connected to the synthesis water outlet of the coalescer; the third distillation unit includes a top liquid outlet and a bottom liquid outlet. The inlet of the low-carbon aldehyde hydrogenation unit is connected to the overhead liquid outlet of the third distillation unit. The inlet of the low-carbon alcohol separation unit is connected to the outlet of the low-carbon aldehyde hydrogenation unit.

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