High alcohol production method and system

Abstract

The invention relates to the technical field of high-carbon alcohol preparation, and discloses a high-carbon alcohol production method and system.The method comprises the steps that under the action of a catalyst, mixed liquid of hydrocarbons, aldehydes, alcohols and water is produced, the aldehydes are converted into the alcohols after hydrotreating, then the alcohols are treated through a cutting tower, and the mixed high-carbon alcohol is obtained; carrying out first separation treatment to obtain mixed high-carbon alcohol with the yield being greater than or equal to 98%; and finally, carrying out second rectification treatment to respectively obtain single high-carbon alcohol with the purity being greater than 99%.

Description

Technical Field

[0001] The present invention relates to the technical field of higher alcohol preparation, and particularly relates to a production method and system for higher alcohols. Background Art

[0002] Higher alcohols generally refer to alcohol compounds containing 6 or more carbon atoms, and can be classified into plasticizer alcohols (C6-C11), detergent alcohols (C12-C20), and higher alkanols (C21-C34) according to their uses. Among them, plasticizer alcohols are one of the raw materials for plasticizers. Plasticizers have excellent plasticizing properties and can be used as plasticizers for polyvinyl chloride, nitrocellulose, polystyrene, ethyl cellulose, nitrile rubber, etc., to improve 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 prepared from higher alcohols have a wide washing range, strong detergency, are easily biodegradable, and cause less pollution, and can be formulated into various surfactants with excellent properties. Higher alkanols with longer carbon chains have important physiological activities and are widely used in functional foods, nutritional preparations, medicines, cosmetics, and high-grade feeds.

[0003] In the prior art, the production methods of higher alcohols mainly include natural oil hydrogenation method, higher olefin hydroformylation method, and alkylaluminum method. The natural oil hydrogenation method uses natural oils such as coconut oil, palm oil, and cashew shell oil as raw materials, and generates higher alcohols through high-pressure hydrogenation. The higher alcohols produced by this method have good quality and biocompatibility, but natural oil raw materials are mainly produced in tropical countries in Southeast Asia, and it is difficult to achieve large-scale production. The higher olefin hydroformylation method uses long-chain α-olefins separated from the petrochemical industry and coal-to-oil products as raw materials, and under the action of a carbonyl cobalt catalyst, hydroformylates to produce long-chain higher aldehydes, and then simply hydrogenates to obtain long-chain higher alcohols. Although this method can get rid of the dependence on natural oil raw materials, the quality of long-chain higher alcohol products is poor, and the ratio of n-alcohol to iso-alcohol in the product is low. It is necessary to separate the iso-alcohol by-products, and at the same time, the relative energy consumption is high and the cost is high. The alkylaluminum method is a chemical synthesis method for producing long-chain higher alcohols using petroleum derivative products as raw materials. Using a triethylaluminum catalyst, ethylene raw materials are processed through triethylaluminum chain growth reaction, oxidation, hydrolysis, rectification and other processes to produce higher alcohols. This method has a large consumption of triethylaluminum catalyst, high cost, poor production flexibility, and has the disadvantages of long process flow and complex technology. Moreover, alkylaluminum is extremely flammable and explosive, posing a great safety hazard.

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

[0005] In view of this, the present invention provides a production method of 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: (1) Under the action of a catalyst, CO reacts with H2 to obtain a mixed solution of aldehyde, alcohol and hydrocarbon; (2) Perform a first rectification treatment on the mixed solution of aldehyde, alcohol and hydrocarbon to obtain a top liquid; (3) Perform a hydrogenation treatment on the top liquid. After the obtained hydrogenation product is separated by a cutting tower, light fractions, middle fractions and heavy fractions are obtained; 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, and T2 > T1; (4) Perform a first separation treatment on the middle fraction to obtain a mixed higher alcohol and a mixed hydrocarbon respectively; (5) Perform a second rectification treatment on the mixed higher alcohol to obtain higher alcohols with single components respectively.

[0007] In some alternative embodiments, in step (2), after the first rectification treatment, a bottom liquid is further obtained.

[0008] In some alternative embodiments, it further includes subjecting the bottom liquid, the light fraction, the heavy fraction and the mixed hydrocarbon to a hydrogenation saturation treatment, and after dehydration, a straight-chain paraffin oil product is obtained.

[0009] In some alternative embodiments, in step (1), the reaction of CO with H2 further includes obtaining residual gas.

[0010] In some alternative embodiments, it further includes washing, heat exchange and a first separation treatment on the residual gas; after the first separation treatment, the liquid is separated by a coalescer to obtain a low-carbon hydrocarbon light oil and synthesis water respectively; the low-carbon hydrocarbon light oil is subjected to the hydrogenation treatment, and after the first separation treatment, the gas is compressed, and a part of it is returned to the reactor in step (1) as the main recycle gas, and the remaining part is subjected to a 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 hydrogen and carbon monoxide are returned to the reactor in step (1) as the external recycle gas.

[0011] In some alternative embodiments, it further includes subjecting the synthesis water to a third rectification treatment, and the top liquid obtained is sequentially subjected to a low-carbon aldehyde hydrogenation treatment and a low-carbon alcohol separation treatment to obtain C1-C5 alcohols and C6 alcohols, and the C6 alcohols are returned to the second rectification treatment in step (5).

[0012] In some alternative embodiments, the second rectification treatment includes precision rectification and / or extractive rectification.

[0013] In some alternative embodiments, the hydrogen-carbon ratio after mixing CO, H2, the internal recycle gas, and the external recycle gas is 2.0 - 2.8.

[0014] In some alternative embodiments, the temperature of the reaction is 170°C - 300°C, the pressure of the reaction is 2.0 MPaG - 6.0 MPaG, and the space velocity is 1800 h -1 -6000 h -1 。

[0015] In some alternative embodiments, the catalyst for the hydrotreating includes a nickel-based catalyst.

[0016] In some alternative embodiments, 115°C < T1 ≤ 140°C, 230°C ≤ T2 ≤ 450°C.

[0017] In a second aspect, the present invention provides a system for the production method described in the first aspect, including: A first distillation unit, whose inlet is connected to the liquid outlet of the reactor; the first distillation unit includes a top liquid outlet and a bottom liquid outlet; A hydrogenation unit, whose inlet is connected to the top liquid outlet of the first distillation unit; A cut column, whose inlet is connected to the outlet of the hydrogenation unit; the cut column includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet; A first separation unit, whose inlet is connected to the middle fraction outlet of the cut column; the first separation unit includes a mixed alcohol outlet and a mixed hydrocarbon outlet; A second distillation unit, whose inlet is connected to the mixed alcohol outlet of the first separation unit.

[0018] In some alternative embodiments, the first distillation unit further includes a bottom liquid outlet.

[0019] In some alternative embodiments, it further includes a hydrogenation saturation unit, whose inlets are respectively connected to the bottom liquid outlet of the first distillation unit, the light fraction outlet and the heavy fraction outlet of the cut column, and the mixed hydrocarbon outlet of the first separation unit.

[0020] In some alternative embodiments, it further includes a washing unit, whose inlet is connected to the gas outlet of the reactor; A heat exchange unit, whose inlet is connected to the outlet of the washing unit; A second separation unit, whose inlet is connected to the outlet of the heat exchange unit; the separation unit includes a liquid outlet and a gas outlet; A coalescer, whose inlet is connected to the liquid outlet of the second separation unit; the coalescer includes a low-carbon hydrocarbon light oil outlet and a synthesis water outlet, and the low-carbon hydrocarbon light oil outlet is connected to the inlet of the hydrogenation unit; A compression device, whose inlet is connected to the gas outlet of the second separation device and whose outlet is connected to the gas inlet of the reactor; A low-temperature oil washing device, whose inlet is connected to the outlet of the compression device; the low-temperature oil washing device includes a gas outlet and a liquefied gas outlet; A pressure swing adsorption device, whose inlet is connected to the gas outlet of the low-temperature 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.

[0021] In some alternative embodiments, a third rectification device is further included, whose inlet is connected to the synthetic water outlet of the coalescer; the third rectification device includes a top liquid outlet and a bottom liquid outlet; A lower-carbon aldehyde hydrogenation device, whose inlet is connected to the top liquid outlet of the third rectification device; A lower-carbon alcohol separation device, whose inlet is connected to the outlet of the lower-carbon aldehyde hydrogenation device.

[0022] Compared with the prior art, the technical solution of the present invention has the following advantages: 1. The production method of higher-carbon alcohols provided by the present invention includes the following steps: under the action of a catalyst, CO reacts with H2 to obtain an aldehyde-alcohol-hydrocarbon mixture; the aldehyde-alcohol-hydrocarbon mixture is subjected to a first rectification treatment to obtain a top liquid; the top liquid is subjected to a hydrogenation treatment, and the obtained hydrogenation product is separated by a cutting tower 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, T2>T1; the middle fraction is subjected to a first separation treatment to respectively obtain a mixed higher-carbon alcohol and a mixed hydrocarbon; the mixed higher-carbon alcohol is subjected to a second rectification treatment to respectively obtain single-component higher-carbon alcohols. The present invention produces a mixed liquid of hydrocarbons, aldehydes, alcohols and water under the action of a catalyst. After hydrogenation treatment, the aldehyde substances are converted into alcohols, and then a mixed higher-carbon alcohol with a boiling point of T1-T2 is obtained through light oil cutting treatment. Then, a mixed higher-carbon alcohol with a yield ≥98% is obtained through the first separation, and finally, single higher-carbon alcohols with a purity >99% are respectively obtained through the second rectification treatment.

[0023] The process flow of the present invention is short, with low investment and low energy consumption, and nearly zero emission of CO2 is achieved, having very good industrialization prospects. Description of the Drawings

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required for the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0025] Figure 1 is the high-carbon alcohol production system in the embodiment of the present invention; Explanation of the reference numerals: Reactor 01, washing device 02, heat exchange device 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. Specific embodiments

[0026] The following embodiments are provided to better further understand the present invention, which is not limited to the best embodiment, and does not limit the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0027] For those not specifying specific experimental steps or conditions in the embodiments, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For reagents or instruments not specifying the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.

[0028] To solve the problems existing in the above-mentioned related technologies, according to the first aspect of the present invention, a method for producing high-carbon alcohol is provided, including the following steps: (1) Under the action of a catalyst, CO reacts with H2 to obtain an aldehyde-alcohol-hydrocarbon mixture; (2) Perform a first distillation treatment on the aldehyde-alcohol-hydrocarbon mixture to obtain a top liquid; (3) Perform a hydrogenation treatment on the top liquid. After the obtained hydrogenation product is separated by a cutting tower, light fractions, middle fractions, and heavy fractions are obtained; wherein, the cutting temperature of the light fractions and the middle fractions is T1, and the cutting temperature of the middle fractions and the heavy fractions is T2, and T2 > T1; (4) Perform a first separation treatment on the middle fractions to obtain a mixed high-carbon alcohol and a mixed hydrocarbon respectively; (5) Perform a second distillation treatment on the mixed high-carbon alcohol to obtain high-carbon alcohols with single components respectively.

[0029] It should be noted that the raw material of the present invention is syngas, and its main components include CO and H2.

[0030] It should be noted that the middle distillate includes a mixture of mixed higher carbon alcohols and mixed hydrocarbons with boiling points from T1 to T2; It should be noted that the top liquid is subjected to hydrogenation treatment to convert the aldehydes therein into alcohols. Then, after separation by a cutting tower, alcohols within the target carbon number range and hydrocarbons with corresponding boiling points are cut out, and then subjected to a first separation treatment to separate the mixed higher carbon alcohols and mixed hydrocarbons. The recovery rate of the mixed higher carbon alcohols is >98%, and the mixed higher carbon alcohols are subjected to a second rectification treatment to obtain higher carbon alcohols with a purity >99% of single components.

[0031] It should be noted that the cutting tower separates light oil into different distillates according to the boiling point range by distillation. In the present invention, 115°C < T1 ≤ 140°C and 230°C ≤ T2 ≤ 450°C.

[0032] It should be noted that in the hydrogenation treatment step, liquid-phase hydrogenation is adopted, and the hydrogenation catalyst includes at least one of nickel-based catalysts. The hydrogenation catalyst has high selectivity and only hydrogenates aldehydes into alcohols, and alcohols cannot be further hydrogenated.

[0033] In the present invention, the preparation method of the nickel-based catalyst refers to Example 1 of Chinese Patent Document CN111215107A and includes the following steps: At a reaction temperature of 100°C, 95 g of Ni(NO3)2·6H2O, 17.8 g of Mg(NO3)2·6H2O, 0.74 g of Co(NO3)2·6H2O, and 2.98 g of Ca(NO3)2·4H2O are dissolved in 0.5 liters of boiling water. At a reaction temperature of 100°C, 75 g of Na2CO3 is dissolved in 0.7 liters of boiling water in a reactor equipped with stirring. Under the condition of rapid stirring, the 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 the Ni - Mg - Co - Ca solution, 11.5 g of diatomaceous earth powder that has been subjected to ammonia treatment is quickly added, and the reaction mixture is stirred for 5 minutes. Subsequently, filtration is carried out, and the filter cake is washed with hot water at 80°C, and the conductivity of the outflowing washing water is detected. When the conductivity drops to 1800 μs, the washing is stopped. At a reaction temperature of 50°C, the filter cake is placed in 0.3 liters of 0.25 wt% NaOH solution, and the reaction suspension is stirred for 3 hours. Subsequently, filtration is carried out, and the filter cake is placed in a drying oven and dried at 60°C for 5 hours, at 80°C for 5 hours, and at 120°C for 10 hours until constant weight. The catalyst is prepared through granulation and tableting processes.

[0034] It should be noted that in the first separation treatment, aromatic hydrocarbons, hydrocarbons, and alcohols are used as solvents, preferably aromatic hydrocarbons; among them, aromatic hydrocarbons include at least one of benzene, toluene, and xylene; hydrocarbons include at least one of pentane, hexane, and heptane; alcohols include at least one of ethylene glycol, isopropyl alcohol, and butanol.

[0035] In some alternative embodiments, the second rectification treatment includes precision rectification and / or extractive rectification, preferably precision rectification, combined with a heat pump process to shorten the process and reduce energy consumption.

[0036] In some alternative embodiments, in step (2), after the first rectification treatment, it further includes obtaining a bottoms liquid, and performing a hydrotreating step on the bottoms liquid, the light fraction, the heavy fraction, and the mixed hydrocarbons, and after dehydration, obtaining a straight-chain alkane oil product.

[0037] It should be noted that the hydrotreating step is performed on the bottoms liquid, the light fraction, the heavy fraction, and the mixed hydrocarbons to convert aldehydes and alcohols therein into hydrocarbons and water, and after dehydration, a straight-chain alkane oil product is obtained, which can be further separated or directly used as a product.

[0038] In some alternative embodiments, in step (1), when CO reacts with H2, it also includes obtaining a residual gas. After washing, heat exchange, and a second separation treatment of the residual gas, after the liquid after the second separation treatment is separated by a coalescer, a light oil of low-carbon hydrocarbons and synthesis water are respectively obtained; the light oil of low-carbon hydrocarbons is subjected to the hydrotreating; after the gas after the second separation treatment is compressed, a part of it is returned as the main recycle gas to the reactor in step (1), and the remaining part is subjected to a cryogenic oil wash treatment to obtain liquefied gas; the gas after the cryogenic oil wash is subjected to pressure swing adsorption to obtain fuel gas, hydrogen, and carbon monoxide, and hydrogen and carbon monoxide are returned as the external recycle gas to the reactor in step (1).

[0039] It should be noted that an internal filter is provided inside the slurry bed reactor to block the cobalt-based catalyst inside the reactor, and the liquid-phase product generated by the reaction flows out of the reactor through the internal filter. The materials inside the reactor are in a gas-liquid-solid three-phase state, at a reaction temperature of 170°C - 300°C, a reaction pressure of 2.0 MPaG - 6.0 MPaG, and a space velocity of 1800 h -1 -6000 h -1In the following reaction, syngas is converted to hydrocarbons, alcohols, aldehydes and water. Among them, alcohols and aldehydes account for more than 50 wt% of the total amount of organic substances. The unreacted syngas and the C1-C4 light hydrocarbons generated by the reaction come out from the top of the reactor, and the solid catalyst particles entrained in the gas are removed by a washing device. The catalyst particles are returned to the reactor. The overhead gas of the washing device is cooled to 40 °C by heat exchange, and light oil of low-carbon hydrocarbons and synthesis water will precipitate. After separation by a separation tank, the light oil of low-carbon hydrocarbons and synthesis water are separated by a coalescer to achieve oil-water separation; the gas phase at the top of the separation tank enters a gas compressor, and after pressurization, a part is returned to the reactor as recycle gas to ensure the space velocity of the reactor; the remaining part enters the low-temperature oil washing treatment to recover the C2-C4 components in the gas and obtain liquefied gas; the gas taken out from the low-temperature oil washing unit enters a pressure swing adsorption (PSA) to separate high-purity hydrogen, CO and fuel gas. Hydrogen and CO are returned to the reactor as recycle gas to effectively adjust the hydrogen-carbon ratio at the inlet of the slurry bed reactor and maintain the balance of C1-C4 hydrocarbons in the recycle gas.

[0040] It should be noted that the low-temperature oil washing treatment is carried out under low temperature (-40 °C to 10 °C) and pressure (1 MPa - 5 MPa) conditions, and the solvent oil (washing oil) is used to selectively absorb the heavy hydrocarbons (carbon atoms ≥ 3) and impurities in the gas, and then the solvent is regenerated and the heavy hydrocarbons are recovered by heating or decompression analysis.

[0041] During the reaction process in the slurry bed reactor, the CO2 generation amount is relatively low, and the CO2 content in the recycle gas is less than 0.1%. Before the recycle gas enters the low-temperature oil washing unit, a decarbonization unit can be set. Preferably, no decarbonization unit is set to shorten the process and reduce the investment.

[0042] In some alternative embodiments, after the synthesis water is subjected to the third rectification treatment, the overhead liquid obtained is successively subjected to low-carbon aldehyde hydrogenation treatment and low-carbon alcohol separation treatment to obtain C1-C5 alcohols and C6 alcohols, and the C6 alcohols are returned to the second rectification treatment.

[0043] It should be noted that the synthesis water contains aldehydes and C1-C6 alcohols. After the third rectification treatment, the aldehydes and alcohols are separated from the water, and then the low-carbon aldehyde hydrogenation treatment is carried out to convert the aldehydes into alcohols, and then the low-carbon alcohol separation treatment is carried out to separate the C1-C5 low-carbon alcohols from the C6 high-carbon alcohols. The C6 is returned to the second rectification treatment, and the C1-C5 low-carbon alcohols are used as products.

[0044] The present invention uses syngas to produce higher alcohols in one step in the presence of a cobalt-based catalyst, and separates and obtains single higher alcohols of C6-C11, straight-chain alkane oil products, liquefied gas and fuel gas.

[0045] It should be noted that the particle size of the cobalt-based catalyst of the present invention is 20 μm - 180 μm. The preparation method of the cobalt-based catalyst refers to Example 1 of Chinese Patent Document CN112892543A and includes the following steps: Dissolve 4.94 g of cobalt nitrate hexahydrate, 0.91 g of zinc nitrate hexahydrate, and 0.23 g of manganese acetate tetrahydrate in 10 g of water to prepare an impregnation solution. Impregnate 8.73 g of activated carbon support with this impregnation solution at room temperature of 298 K and then air-dry for about 10 hours. After there is no flowing water on the catalyst surface, place it in an oven at 313 K and dry for 24 h. After taking it out, gradually heat it to 573 K in argon and calcine for 20 hours to obtain the dry-based catalyst precursor A. Then dissolve 0.074 g of sodium nitrate in 10 g of water to prepare an impregnation solution. Impregnate the dry-based catalyst precursor A with this impregnation solution at room temperature of 298 K and then air-dry for about 10 hours. After there is no flowing water on the catalyst surface, place it in an oven at 313 K and dry for 24 h. After taking it out, gradually heat it to 573 K in argon and calcine for 20 hours to obtain the dry-based catalyst precursor B. Take out the dry-based catalyst precursor B and load it into a fixed-bed reactor with a diameter of 9 mm, with a filling amount of 2 mL and an airspeed of 2000 h -1 . The catalyst is gradually heated to 673 K in hydrogen and reduced for 15 hours, and then cooled to 423 K.

[0046] In a second aspect, the present invention provides a system for the production method described in the first aspect, including: A first rectification device, whose inlet is connected to the liquid outlet of the reactor; the first rectification device includes a top liquid outlet and a bottom liquid outlet; A hydrogenation device, whose inlet is connected to the top liquid outlet of the first rectification device; A cutting column, whose inlet is connected to the outlet of the hydrogenation device; the cutting column includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet; A first separation device, whose inlet is connected to the middle fraction outlet of the cutting column; the first separation device includes a mixed alcohol outlet and a mixed hydrocarbon outlet; A second rectification device, whose inlet is connected to the mixed alcohol outlet of the first separation device.

[0047] In some alternative embodiments, it further includes a hydrogenation saturation device, whose inlets are respectively connected to the bottom liquid outlet of the first rectification device, the light fraction outlet and the heavy fraction outlet of the cutting column, and the mixed hydrocarbon outlet of the first separation device.

[0048] In some alternative embodiments, it further includes a washing device, whose inlet is connected to the gas outlet of the reactor; A heat exchange device, whose inlet is connected to the outlet of the washing device; A second separation device, whose inlet is connected to the outlet of the heat exchange device; the second separation device includes a liquid outlet and a gas outlet; A coalescer, whose inlet is connected to the liquid outlet of the second separation device; the coalescer includes a light oil outlet of low-carbon hydrocarbons and a synthetic water outlet, and the light oil outlet of low-carbon hydrocarbons is connected to the inlet of the hydrogenation device; A compression device, whose inlet is connected to the gas outlet of the second separation device and whose outlet is connected to the gas inlet of the reactor; A low-temperature oil washing device, whose inlet is connected to the outlet of the compression device; the low-temperature oil washing device includes a gas outlet and a liquefied gas outlet; A pressure swing adsorption device, whose inlet is connected to the gas outlet of the low-temperature 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.

[0049] In some alternative embodiments, a third rectification device is further included, whose inlet is connected to the synthetic water outlet of the coalescer; the third rectification device includes a top liquid outlet and a bottom liquid outlet; A low-carbon aldehyde hydrogenation device, whose inlet is connected to the top liquid outlet of the third rectification device; A low-carbon alcohol separation device, whose inlet is connected to the outlet of the low-carbon aldehyde hydrogenation device.

[0050] It should be noted that the second rectification device includes a plurality of rectification towers connected in series.

[0051] The present invention will be further described in detail below with reference to specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present invention.

[0052] Embodiment 1 As Figure 1 shown, the present 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 rectification 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 rectification device 13, a hydrogenation saturation device 14, a third rectification device 15, a low-carbon aldehyde hydrogenation device 16, and a low-carbon alcohol separation device 17; specifically: A washing device 02, whose inlet is connected to the gas outlet of the reactor 01 and whose solid outlet is connected to the catalyst inlet of the reactor 01; A heat exchange device 03, whose inlet is connected to the gas outlet of the washing device 02; A second separation device 04, whose inlet is connected to the liquid outlet of the heat exchange device 03; the second separation device 04 includes a liquid outlet and a gas outlet; A coalescer 05, whose inlet is connected to the liquid outlet of the second separation device 04; the coalescer 05 includes a light oil outlet for low-carbon hydrocarbons and a synthetic water outlet, and the light oil outlet for low-carbon hydrocarbons is connected to the inlet of a hydrogenation device 10; A compression device 06, whose inlet is connected to the gas outlet of the second separation device 04, and whose outlet is connected to the gas inlet of the reactor 01; A low-temperature oil washing device 08, whose inlet is 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; A pressure swing adsorption device 09, whose inlet is 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 the carbon monoxide outlet are connected to the gas inlet of the reactor 01; A first rectification device 07, whose inlet is connected to the liquid outlet of the reactor 01; the first rectification device 07 includes a top liquid outlet and a bottom liquid outlet; A hydrogenation device 10, whose inlet is connected to the top liquid outlet of the first rectification device 07; A cutting column 11, whose inlet is connected to the outlet of the hydrogenation device 10; the cutting column 11 includes a light fraction outlet, a middle fraction outlet, and a heavy fraction outlet; A first separation device 12, whose inlet is connected to the middle fraction outlet of the cutting column 11; the first separation device 12 includes a mixed alcohol outlet and a mixed hydrocarbon outlet; A second rectification device 13, whose inlet is connected to the mixed alcohol outlet of the first separation device 12; A hydrogenation saturation device 14, whose inlets are respectively connected to the bottom liquid outlet of the first rectification device 07, the light fraction outlet and the heavy fraction outlet of the cutting column 11, and the mixed hydrocarbon outlet of the first separation device 12; A third rectification device 15, whose inlet is connected to the synthetic water outlet of the coalescer 05; the third rectification device 15 includes a top liquid outlet and a bottom liquid outlet; A low-carbon aldehyde hydrogenation device 16, whose inlet is connected to the top liquid outlet of the third rectification device 15; A low-carbon alcohol separation device 17, whose inlet is connected to the outlet of the low-carbon aldehyde hydrogenation device 16.

[0053] Example 2 Using the system of Example 1, this example provides a method for producing higher alcohols, including the following steps: (1) Combine the synthesis gas (molar ratio of hydrogen to carbon is 2.05) with the recycle gas and enter a slurry bed reactor filled with a cobalt-based catalyst with a particle size of 20 μm - 180 μm. The volume ratio of the recycle gas to the synthesis gas is 20, the reaction temperature is 230 °C, the reaction pressure is 3.0 MPaG, and the space velocity is 2600 h -1 , after the reaction ends, an aldehyde-alcohol-hydrocarbon mixture and residual gas are obtained; (2) The residual gas includes unreacted syngas and C1-C4 light hydrocarbons generated by the reaction. It comes out from the top of the reactor and enters the scrubbing tower to wash away the solid catalyst particles entrained in the gas and then returns 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 synthesis water are precipitated. After separation in a separation tank, the low-carbon hydrocarbon light oil and synthesis water are separated through a coalescer to achieve oil-water separation, obtaining low-carbon hydrocarbon light oil and synthesis water. The gas phase at the top of the separation tank enters a compressor. After pressurization, a part of it returns to the reactor as the main recycle gas to ensure the reactor space velocity; the remaining part enters a low-temperature oil washing unit with a temperature of -30 °C and a pressure of 2.0 - 4.0 MPa. The solvent oil is light oil to recover C2-C4 components (containing a small amount of C2, mainly C3-C4 components) in the gas, obtaining liquefied gas; the gas taken out from the low-temperature oil washing unit enters a pressure swing adsorption (PSA) unit 3 to separate high-purity H2, CO, and fuel gas. H2 and CO return to the reactor as the external recycle gas to control the hydrogen-carbon ratio of the feed at the inlet of the slurry bed to be 2.12; (3) An internal filter is provided inside the slurry bed reactor. The internal filter blocks the catalyst inside the reactor, and the aldehyde-alcohol-hydrocarbon mixture generated by the reaction flows out of the reactor through the internal filter and is separated in the first distillation column to obtain overhead liquid and bottom liquid; (4) The low-carbon hydrocarbon light oil and the overhead liquid are combined and then enter the light oil hydrogenation unit. The hydrogenation catalyst is a nickel-based catalyst to convert the aldehydes therein into alcohols, and then enter the light oil cutting unit with a temperature range of 140 °C - 245 °C to obtain light fractions, middle fractions, and heavy fractions; among them, the light fraction includes a mixture of C1-C5 alcohols and C5-C8 hydrocarbons, the heavy fraction includes a mixture of C12-C22 alcohols and C14-C24 hydrocarbons, the middle fraction includes a mixture of C6-C11 alcohols and C9-C13 hydrocarbons. Then the middle fraction enters the adsorption separation unit with toluene as the solvent to separate the mixture of C6-C11 alcohols and C8-C14 hydrocarbons, obtaining a mixture of C9-C14 hydrocarbons and a mixture of C6-C11 alcohols respectively. The recovery rate of the mixed alcohols is 98%. The mixed alcohols enter the second distillation device and are separated by precise distillation technology to obtain single high-carbon alcohols of C6, C7, C8, C9, C10, and C11 with a product purity greater than 99%; the C6-C11 high-carbon alcohols account for 28% of the product. The product includes high-carbon alcohols, low-carbon alcohols, liquefied gas, fuel gas, and straight-chain alkane oils; (5) The bottom liquid, light fraction, heavy fraction, and the C8-C14 hydrocarbon mixture obtained from the adsorption separation unit are combined and enter the hydrogenation saturation unit to convert the aldehydes and alcohols therein into hydrocarbons and water. After dehydration, straight-chain alkane oils are obtained; The synthetic water separated by the coalescer contains aldehydes and C1-C6 alcohols, which first enter the third distillation column for separation to separate the aldehydes and alcohols from the water. The overhead liquid enters the low-carbon aldehyde hydrogenation unit to convert the aldehydes into alcohols, and then enters the low-carbon alcohol separation unit to separate C1-C5 low-carbon alcohols from C6. The C6 is returned to the second distillation column to obtain C1-C5 low-carbon alcohols, and the C1-C5 low-carbon alcohols account for 6% of the product.

[0054] Example 3 This example provides a method for producing higher alcohols, which is basically the same as the steps in Example 1, except that in step (4), T1 in the cutting column is controlled at 150 °C and T2 is controlled at 360 °C to obtain light fractions, middle fractions, and heavy fractions; among them, the light fractions include a mixture of C1-C5 alcohols and a mixture of C5-C8 hydrocarbons, the heavy fractions include a mixture of C19-C22 alcohols and a mixture of C22-C24 hydrocarbons, the middle fractions include a mixture of C6-C18 alcohols and a mixture of C9-C21 hydrocarbons, and the C5-C18 higher alcohols account for 42% of the product.

[0055] Comparative Example 1 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 in step (4) is omitted, and higher alcohols cannot be produced.

[0056] Obviously, the above examples are only for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for producing higher alcohols, characterized in that, It includes the following steps: (1) Under the action of a catalyst, CO reacts with H2 to obtain a mixture of aldehyde, alcohol and hydrocarbon; (2) Perform a first rectification treatment on the aldehyde, alcohol and hydrocarbon mixture to obtain a top liquid; (3) Perform a hydrogenation treatment on the top liquid. After the obtained hydrogenation product is separated by a cutting tower, light fraction, middle fraction and heavy fraction are obtained. Among them, 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; (4) Perform a first separation treatment on the middle fraction to obtain a mixture of higher carbon alcohols and a mixture of hydrocarbons respectively; (5) Perform a second rectification treatment on the mixture of higher carbon alcohols to obtain single-component higher carbon alcohols respectively.

2. The method for producing higher alcohols according to claim 1, characterized in that, In step (2), after the first rectification treatment, it further includes obtaining a bottom liquid; It further includes performing a hydrogenation saturation treatment on the bottom liquid, the light fraction, the heavy fraction and the mixture of hydrocarbons, and after dehydration, obtaining a straight-chain alkane oil product.

3. The method for producing a higher alcohol according to claim 1, wherein, In step (1), the reaction of CO with H2 further includes obtaining residual gas; It further includes performing washing, heat exchange and a second separation treatment on the residual gas; after the liquid after the second separation treatment is separated by a coalescer, light oil of low-carbon hydrocarbons and synthesis water are obtained respectively; the light oil of low-carbon hydrocarbons is subjected to the hydrogenation treatment, and after the gas after the second separation treatment is compressed, a part of it is returned to the reactor in step (1) as the main circulating gas, and the remaining part is subjected to a low-temperature oil washing treatment to obtain liquefied gas; the gas after the low-temperature oil washing is subjected to pressure swing adsorption to obtain fuel gas, hydrogen and carbon monoxide, and hydrogen and carbon monoxide are returned to the reactor in step (1) as the external circulating gas.

4. The method for producing higher alcohols according to claim 3, characterized in that, It further includes performing a third rectification treatment on the synthesis water, and the top liquid obtained is successively subjected to a hydrogenation treatment of low-carbon aldehyde and a separation treatment of low-carbon alcohol to obtain C1-C5 alcohol and C6 alcohol, and the C6 alcohol is returned to the second rectification treatment in step (5).

5. The method for producing a higher alcohol according to claim 1, characterized in that, The second rectification treatment includes precision rectification and / or extractive rectification.

6. The method for producing higher alcohols according to claim 3, characterized in that, The hydrogen-carbon ratio after mixing CO, H2, the internal circulating gas and the external circulating gas is 2.0 - 2.8; And / or, the temperature of the reaction is 170°C - 300°C, the pressure of the reaction is 2.0 MPaG - 6.0 MPaG, and the space velocity is 1800 h -1 -6000 h -1 ; and / or, the catalyst for the hydrogenation treatment includes a nickel-based catalyst; and / or, 115°C < T1 ≤ 140°C, 230°C ≤ T2 ≤ 450°C.

7. A system for the method for producing higher alcohols according to any one of claims 1-6, characterized in that, It includes: A first rectification device, whose inlet is connected to the liquid outlet of the reactor; the first rectification device includes a top liquid outlet; A hydrogenation device, whose inlet is connected to the top liquid outlet of the first rectification device; A cutting tower, whose inlet is connected to the outlet of the hydrogenation device; the cutting tower includes a light fraction outlet, a middle fraction outlet and a heavy fraction outlet; A first separation device, whose inlet is connected to the middle fraction outlet of the cutting tower; the first separation device includes a mixed alcohol outlet and a mixed hydrocarbon outlet; A second rectification device, whose inlet is connected to the mixed alcohol outlet of the first separation device.

8. The production system of higher alcohols according to claim 7, characterized in that, The first rectification device further includes a bottom liquid outlet; It further includes a hydrogenation saturation device, whose inlets are respectively connected to the bottom liquid outlet of the first rectification device, the light fraction outlet and the heavy fraction outlet of the cutting tower, and the mixed hydrocarbon outlet of the first separation device.

9. The production system of higher alcohols according to claim 8, characterized in that, It further includes a washing device, whose inlet 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; A second separation device, the inlet of which is 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 device; the coalescer includes a light oil outlet for low-carbon hydrocarbons and a synthetic water outlet, and the light oil outlet for low-carbon hydrocarbons is connected to the inlet of the hydrogenation device; 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 low-temperature oil washing device, the inlet of which is connected to the outlet of the compression device; the low-temperature oil washing device includes a gas outlet and a liquefied gas outlet; A pressure swing adsorption device, the inlet of which is connected to the gas outlet of the low-temperature 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 of higher alcohols according to claim 9, characterized in that, It further includes a third rectification device, the inlet of which is connected to the synthetic water outlet of the coalescer; the third rectification device includes a top liquid outlet and a bottom liquid outlet; A low-carbon aldehyde hydrogenation device, the inlet of which is connected to the top liquid outlet of the third rectification device; A low-carbon alcohol separation device, the inlet of which is connected to the outlet of the low-carbon aldehyde hydrogenation device.

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