Production system and method for preparing high carbon aldehydes by hydroformylation of alkenes and alkanes via Fischer-Tropsch synthesis

Abstract

A production system and method for preparing high-carbon aldehydes by hydroformylation of alkenes via Fischer-Tropsch synthesis are disclosed. The system includes: a reaction unit for hydroformylation of raw olefins, an aqueous catalyst solution, and syngas to obtain a product mixture; a separation unit for separating the product mixture to obtain crude aldehydes, an aqueous catalyst solution, and tail gas; and a tail gas treatment unit for separating hydrogen from the tail gas and transferring it to the reaction unit. The volume ratio of hydrogen to carbon monoxide in the syngas is 1.3–4:1. This invention increases the hydrogen partial pressure and the amount of hydrogen dissolved in the reaction solution by increasing the volume ratio of hydrogen in the syngas. This reduces the formation of rhodium, a polycarbonyl metal, during the reaction, thereby inhibiting the loss of rhodium from the aqueous catalyst solution to the organic phase. This ensures that the aqueous catalyst solution maintains good catalytic activity in multiple production cycles. Furthermore, a higher hydrogen volume ratio significantly improves the selectivity of straight-chain aldehydes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Fischer-Tropsch synthesis olefin alkyne hydroformylation, and in particular to a production system and method for preparing high-carbon aldehyde based on Fischer-Tropsch synthesis olefin alkyne hydroformylation. BACKGROUND

[0002] Olefin hydroformylation has good chemical selectivity and regioselectivity, and can introduce a chemically active aldehyde group in the molecule of a compound, which can further generate alcohol, acid, amine, unsaturated aldehyde and other compounds through hydrogenation, oxidation, reductive amination, condensation and other reactions. Therefore, the hydroformylation reaction is widely used in the synthesis process of bulk chemicals, such as plasticizer alcohol (C6-C10), detergent alcohol (C12-C16), industrial solvent, and fine chemicals for pharmaceuticals, cosmetics and personal care products.

[0003] In recent years, with the maturity and gradual expansion of the Fischer-Tropsch coal-to-oil project, Fischer-Tropsch synthetic oil has reached a scale of tens of millions of tons. The intermediate products of coal-based Fischer-Tropsch synthesis contain a large amount of linear alpha-olefins, such as the linear alpha-olefins in Fischer-Tropsch oil wash naphtha, which have a mass fraction of up to 69%. The method of hydroformylation to produce high-carbon aldehyde is the most effective way to solve the problem of outlet of tens of millions of tons of Fischer-Tropsch synthetic oil and effectively utilize the linear alpha-olefins to produce high-value-added fine chemicals. Through simple rectification cutting, C5 and above single-carbon hydrocarbon components are obtained, and the alpha-olefins therein are directly used to react with synthesis gas under the action of a catalyst to synthesize high-carbon aldehyde, which is then hydrogenated to produce high-carbon alcohol.

[0004] Currently, the industrial production of high-carbon aldehyde based on Fischer-Tropsch synthesis olefin alkyne hydroformylation mainly adopts a homogeneous catalytic process. For example, patent CN113087601A discloses a method for preparing linear aldehyde with high selectivity based on Fischer-Tropsch olefin hydroformylation. This method uses oil-soluble ligand BISBI and rhodium precursor to catalyze Fischer-Tropsch high-carbon olefin hydroformylation to prepare intermediate product aldehyde. Although the normal-to-isomer ratio can reach more than 20, the separation of catalyst and product needs to use salt precipitation and high-vacuum rectification, which has the problems of complicated separation process and high cost.

[0005] The olefin hydroformylation reaction in a water-organic heterogeneous catalytic system can better solve the separation problem of catalyst and product, and the recycling of catalyst can effectively reduce the cost. At present, in the heterogeneous catalytic system, the mature bisphosphine ligand BISBIS can effectively improve the regioselectivity of aldehyde, but due to the long synthesis route and poor thermal stability, the industrial application is still difficult. The water-soluble rhodium phosphine (Rh / TPPTS) catalytic system uses TPPTS as the phosphine ligand, which can effectively reduce the cost of phosphine ligand and has good olefin conversion rate, but the normal-isomer ratio is low, the straight-chain aldehyde selectivity is poor, and at the same time, the loss amount of rhodium in the catalyst aqueous solution is large, which causes the increase of production cost and the decrease of reaction speed. SUMMARY

[0006] One object of the present application is to provide a production system for preparing high-carbon aldehyde based on Fischer-Tropsch synthesis olefin hydroformylation, which uses a water-soluble rhodium phosphine (Rh / TPPTS) catalytic system. The synthesis gas used in the hydroformylation reaction in the reaction unit has a high hydrogen-carbon volume ratio, which not only improves the proportion of straight-chain aldehyde in the product, but also effectively inhibits the loss amount of rhodium in the catalyst aqueous solution. At the same time, the excess hydrogen gas is recovered by using a tail gas treatment unit, which improves the utilization rate of hydrogen gas and realizes the industrial production of high-carbon aldehyde based on Fischer-Tropsch synthesis olefin hydroformylation.

[0007] The present application is realized by the following technical solutions:

[0008] The production system for preparing high-carbon aldehyde by Fischer-Tropsch synthesis olefin hydroformylation comprises:

[0009] A reaction unit for hydroformylation reaction of raw material olefin, catalyst aqueous solution, and synthesis gas comprising hydrogen and carbon monoxide to obtain a product mixture;

[0010] A separation unit for separating the product mixture to obtain crude aldehyde, catalyst aqueous solution, and tail gas, and delivering the catalyst aqueous solution to the reaction unit;

[0011] A tail gas treatment unit for separating hydrogen in the tail gas and delivering the hydrogen to the reaction unit;

[0012] Wherein, the volume ratio of hydrogen and carbon monoxide in the synthesis gas is 1.5-3:1.

[0013] In the technical solution, the production system is used for preparing high-carbon aldehyde by Fischer-Tropsch synthesis olefin hydroformylation. The Fischer-Tropsch synthesis olefin is cut by separation to obtain single-carbon hydrocarbon compounds, and the alpha-olefin in each single-carbon hydrocarbon compound is directly used to produce high-carbon aldehyde by hydroformylation reaction.

[0014] In the technical solution, the production system comprises three main parts: a reaction unit, a separation unit and a tail gas treatment unit. In the reaction unit, the raw material olefin after separation and cutting of the Fischer-Tropsch synthesis olefin-alkane mixture is mixed with the aqueous catalyst solution and the synthesis gas, and a product mixture is obtained by performing a hydroformylation reaction under high temperature and high pressure. After cooling, the product mixture enters the separation unit to stand and stratify, and the lower layer of the liquid phase is the aqueous phase, the upper layer is the organic phase, and the upper layer of the liquid phase is the gas phase. The main component of the organic phase is the crude aldehyde obtained by the hydroformylation reaction of the olefin; the main component of the aqueous phase is the aqueous catalyst solution, which can be transported back to the reaction unit through a pipeline and added to the reaction system for recycling; the tail gas of the gas phase contains unreacted hydrogen, carbon monoxide, inert gas, water and a small amount of organic matter, and the tail gas is treated by the tail gas treatment unit to obtain hydrogen and release gas, which is transported back to the reaction unit through a pipeline and used as part of the synthesis gas for recycling. By using the water-soluble heterogeneous catalyst system, the aqueous catalyst solution and the crude aldehyde in the product mixture can be quickly separated, which can significantly improve the separation efficiency, prolong the service life of the catalyst and reduce the production cost compared with the traditional separation of the organic phase and the aqueous phase by using extraction, direct high-temperature distillation and the like.

[0015] In the heterogeneous catalyst system, the form of the active species rhodium phosphine complex in the olefin hydroformylation reaction will dynamically change, one of which is the oil-soluble metal rhodium polycarbonyl complex, which has poor catalytic activity and will reduce the reaction rate of the olefin hydroformylation reaction. Moreover, the oil-soluble metal rhodium polycarbonyl complex will cause the loss of rhodium from the aqueous phase to the organic phase, resulting in a decrease in the effectiveness of the aqueous catalyst solution during the recycling reaction.

[0016] In the technical solution, the synthesis gas has a high hydrogen to carbon volume ratio. Specifically, the volume ratio of hydrogen to carbon monoxide in the synthesis gas is 1.3-4:1. Through research, it is found that setting the volume ratio of hydrogen to carbon monoxide in the synthesis gas to 1.3-4:1 can increase the hydrogen partial pressure in the reaction system and the amount of hydrogen dissolved in the reaction liquid, thereby reducing the generation of metal rhodium polycarbonyl complex during the reaction, inhibiting the loss of rhodium in the aqueous catalyst solution to the organic phase, and ensuring that the aqueous catalyst solution can maintain good catalytic activity during recycling production. In addition, after the volume ratio of hydrogen is increased, the selectivity of linear aldehyde will be significantly improved, and more high-carbon linear aldehyde can be obtained, which is desirable for the Fischer-Tropsch synthesis olefin-alkane hydroformylation reaction. In one or more embodiments, the synthesis gas can be prepared from coal, natural gas or carbon dioxide. Preferably, the volume ratio of hydrogen to carbon monoxide in the synthesis gas is 1.5-2.6:1, and more preferably, the volume ratio is 2-2.6:1.

[0017] Further, the aqueous catalyst solution comprises a rhodium catalyst, a water-soluble phosphine ligand and a cosolvent, wherein the content of the rhodium catalyst is 50-300 ppm, the concentration of the water-soluble phosphine ligand is 6%-10% by weight, and the concentration of the cosolvent is 40-70% by weight. In the technical solution, the aqueous catalyst solution comprises a rhodium catalyst, a water-soluble phosphine ligand and a cosolvent. In some embodiments, the rhodium catalyst is one or more of RhCl3·nH2O, Rh2(CH3COO)4, Rh(acac)(CO)2 and HRh(CO)(TPPTS)3, and acac is an acetylacetone anion. In one or more preferred embodiments, the rhodium catalyst is Rh(acac)(CO)2 and / or HRh(CO)(TPPTS)3. In some preferred embodiments, the water-soluble phosphine ligand is TPPTS, i.e. sodium triphenylphosphine-3,3',3''-sulfonate. In some preferred embodiments, the cosolvent is one or more of methanol, isopropanol, butanol and liquid polyethylene glycol.

[0018] Further, the volume ratio of the aqueous catalyst solution to the raw olefin is 2-6:1. When the volume ratio of the aqueous catalyst solution to the raw olefin is too low, the water-oil contact area is reduced, further reducing the catalytic reaction activity. When the volume ratio of the aqueous catalyst solution to the raw olefin is too high, although the oil-water contact area is increased, the unit production capacity of the olefin hydroformylation reaction to prepare aldehydes and / or alcohols is reduced, reducing the efficiency of industrial production. Preferably, the volume ratio of the aqueous catalyst solution to the raw olefin is 3-5:1.

[0019] As a preferred embodiment of the present application, the reaction unit comprises a reactor and a static mixer, and the static mixer is used to mix the raw olefin, the aqueous catalyst solution, the synthesis gas and deliver them into the reactor for the hydroformylation reaction.

[0020] In the technical solution, the reaction unit comprises a reactor and a static mixer, and the outlet of the static mixer is connected to the inlet of the tank reactor through a pipeline. The raw olefin, the aqueous catalyst solution, hydrogen and carbon monoxide can be effectively dispersed and mixed in the static mixer, which can on the one hand intensify the highly dispersed and mixed three phases of gas phase, water phase and organic phase, and strengthen the mass transfer between the water-organic two phases, so that the reaction mixture can quickly undergo the hydroformylation reaction after entering the reactor. On the other hand, more importantly, since the hydrogen volume fraction in the synthesis gas is large, the use of the static mixer can greatly promote the solubility of hydrogen in the reaction liquid, thereby better inhibiting the generation of oil-soluble metal rhodium carbonyl, stabilizing the active species of the rhodium phosphine complex, further inhibiting the amount of catalyst deactivation and loss to the organic phase, and ensuring the long-term stability and service life of the catalyst without the need for reactivation.

[0021] As another preferred embodiment of the present application, the tail gas treatment unit comprises a membrane separation device, which comprises a demister, a filter and a membrane separator connected in sequence, wherein the demister is communicated with the separation unit through the second pipeline, and the permeation side of the membrane separator is communicated with the reaction unit through the fourth pipeline.

[0022] In the technical solution, the tail gas treatment unit comprises a membrane separation device, and the demister of the membrane separation device is communicated with the phase separator of the separation unit through the second pipeline. After being treated by the separation unit, the tail gas contains unreacted excess hydrogen, inert gas, water, a small amount of organic matter and the like. The demister is used to eliminate the foam formed by the olefins, alkanes and other impurities in the tail gas. The filter is used to reduce the solid-phase impurities and water in the tail gas. The permeation side of the membrane separator is connected to the reaction unit through the fourth pipeline. The hydrogen entering the permeation side can reconstitute the synthesis gas together with the carbon monoxide after being transported through the fourth pipeline, and then enter the reaction unit to participate in the hydroformylation reaction. The remaining release gas on the non-permeation side of the tail gas mainly contains inert gas and other substances, which are released after subsequent treatment. In the technical solution, in view of the high hydrogen volume ratio in the synthesis gas, the membrane separation device is used in the tail gas treatment unit to recover the excess hydrogen. 95% of the hydrogen can be recovered and recycled for the hydroformylation reaction, which effectively reduces the production cost and reduces the hydrogen content in the release gas.

[0023] Further, the separation unit comprises a phase separator and a first water cooler between the phase separator and the reactor. The organic phase outlet of the phase separator is connected with an extraction unit through the first pipeline. The top of the phase separator is communicated to the tail gas treatment unit through the second pipeline. The bottom of the phase separator is communicated to the reaction unit through the third pipeline.

[0024] In the technical solution, the product mixture after the reaction is cooled by the first water cooler and then enters the phase separator for standing. The phase separator is preferably a chromatograph. The gas phase in the product mixture enters the demister of the tail gas treatment unit through the top of the phase separator and the second pipeline. The water phase in the lower layer of the product mixture is pumped into the static mixer of the reaction unit through the third pipeline. The organic phase in the upper layer of the product mixture is connected to the extraction unit inside or outside the system through the first pipeline.

[0025] As a preferred embodiment of the extraction unit in the present application, specifically, the extraction unit comprises an extraction column and a falling film evaporator. The crude aldehyde flows from bottom to top in the extraction column, and is mixed and extracted with the buffer flowing from top to bottom in countercurrent. The product aldehyde after extraction is discharged from the top of the extraction column. The buffer after extraction is transported to the falling film evaporator through the bottom of the extraction column. The falling film evaporator is used to concentrate the buffer after extraction. The top of the falling film evaporator is communicated with the extraction column. The bottom of the falling film evaporator is communicated with the reaction unit through the fifth pipeline.

[0026] In the technical solution, the extraction unit comprises an extraction tower and a falling film evaporator. The extraction tower preferably adopts a packed tower. The upper organic phase in the phase separator, i.e. the crude aldehyde, is pumped into the lower part of the extraction tower through the first pipeline, enters the second chamber of the extraction tower, and flows from bottom to top in the extraction tower, and finally is discharged through the top of the extraction tower. After the buffer solution enters the first chamber in the upper part of the extraction tower, it flows from top to bottom, fully contacts and mixes with the organic phase in the packed tower, and extracts the catalyst in the organic phase. The buffer solution after extraction is transported from the bottom of the extraction tower to the falling film evaporator for concentration. The heavy components obtained by concentration contain rhodium catalysts, which can be returned to the reaction unit through the fifth pipeline. The light components obtained by concentration are mainly water, de-buffering agents, and form a buffer solution which enters the first chamber of the extraction tower. The rhodium catalysts lost to the organic phase can be further extracted by the extraction tower and the falling film evaporator, and the loss of rhodium catalysts in the reaction system is reduced.

[0027] Further, the buffer solution comprises 0.02-0.5% water-soluble phosphine ligand and 0.5-1.5% disodium hydrogen phosphate, and the pH value of the buffer solution is 8-9. In the technical solution, the buffer solution can not only extract the rhodium catalysts entrained in the crude aldehyde, but also the water-soluble phosphine ligand TPPTS in the buffer solution can coordinate with the rhodium catalysts with poor water solubility such as [HRh(CO)3TPPTS] to form rhodium catalysts with good water solubility such as [HRh(CO)2TPPTS2], further reducing the content of rhodium catalysts in the crude aldehyde. In addition, maintaining the pH value of the buffer solution at 8-9 is beneficial to improving the solubility of the ligand and the rhodium catalyst in water, and preferably, the pH value of the buffer solution is 8.2-8.7.

[0028] Another object of the present application is to provide a production method for preparing high-carbon aldehydes based on Fischer-Tropsch synthesis alkenes hydroformylation based on any one of the aforementioned production systems. The method specifically comprises the following steps:

[0029] Under certain pressure and temperature, a reaction system composed of raw material alkenes, catalyst aqueous solution and synthesis gas undergoes hydroformylation reaction to obtain a product mixture;

[0030] The product mixture is cooled and settled to separate into crude aldehyde, catalyst aqueous solution and tail gas. The lower catalyst aqueous solution and hydrogen in the tail gas are returned to the reaction system after treatment and recovery, and the upper crude aldehyde is extracted by a buffer solution to obtain product aldehyde;

[0031] The buffer solution after extraction is concentrated, the light components distilled out are used to form the buffer solution for extracting the crude aldehyde again, and the heavy components at the bottom of the tank are returned to the reaction system;

[0032] The buffer solution comprises 0.02-0.5% water-soluble phosphine ligand and 0.5-1.5% disodium hydrogen phosphate, and the pH value of the buffer solution is 8-9.

[0033] Further, the reaction temperature of the hydroformylation reaction is 90-120 DEG C, and the reaction pressure is 1.0-4.0 MPa. Preferably, the reaction temperature is 105-110 DEG C, and the pressure is 1.5-2.5 MPa. In some embodiments, the reaction time is 2-6 hours.

[0034] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0035] 1. By increasing the volume ratio of hydrogen in the synthesis gas, the present application increases the hydrogen partial pressure in the reaction system and the amount of hydrogen dissolved in the reaction liquid, which can reduce the generation of metal rhodium polycarbonyl in the reaction process, thereby inhibiting the loss of rhodium in the aqueous catalyst solution to the organic phase, ensuring that the aqueous catalyst solution can maintain good catalytic activity in multiple cycle production. In addition, a higher volume ratio of hydrogen can significantly improve the selectivity of linear aldehydes.

[0036] 2. The static mixer can not only strengthen the high dispersion and mixing of the gas phase-water phase-organic phase three phases, strengthen the mass transfer between the water-organic two phases, and facilitate the hydrogen formylation reaction after the reaction system enters the reactor, but also greatly promote the solubility of hydrogen in the reaction liquid due to the large volume ratio of hydrogen in the synthesis gas, thereby better inhibiting the generation of oil-soluble metal rhodium polycarbonyl, stabilizing the active species of rhodium phosphine complex, and further inhibiting the amount of catalyst deactivation and loss to the organic phase.

[0037] 3. The present application adopts a membrane separation device to recover excess hydrogen in the tail gas treatment unit according to the high volume ratio of hydrogen in the synthesis gas, which can recover 95% of the hydrogen for recycling in the hydroformylation reaction, effectively reducing the production cost and the hydrogen content in the released gas.

[0038] 4. The extraction column and falling film evaporator can further extract the rhodium catalyst lost to the organic phase, reducing the loss of rhodium catalyst in the reaction system. Moreover, the buffer solution used in the extraction column not only has the ability to extract the catalyst, but also contains water-soluble phosphine ligand TPPTS, which can coordinate with the rhodium catalyst with poor water solubility such as [HRh(CO)3TPPTS] to form rhodium catalyst with better water solubility such as [HRh(CO)2TPPTS2], further reducing the rhodium catalyst content in the crude aldehyde, and the pH value of the buffer solution 8-9 is also conducive to improving the solubility of the ligand and the rhodium catalyst in water.

[0039] 5. The water-soluble heterogeneous catalyst system used in the present application can realize the rapid separation of the catalyst aqueous solution and the crude aldehyde in the product mixture, and the production method has the advantages of simple process, high raw material utilization rate, high selectivity of linear aldehydes, effectively reducing the production cost, and great industrial value. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0041] Figure 1 Structure diagram of production system of specific embodiment of the application;

[0042] Figure 2 Structure diagram of membrane separation device in specific embodiment of the application;

[0043] Figure 3 Structure diagram of extraction tower in specific embodiment of the application;

[0044] Figure 4 Flow chart of production method in specific embodiment of the application.

[0045] Markings in the drawings and corresponding names of parts:

[0046] 1-reactor, 2-phase separator, 3-membrane separation device, 31-membrane separator, 32-filter, 33-foam remover, 34-heater, 35-second water cooler, 36-third water cooler, 4-extraction tower, 41-first chamber, 42-second chamber, 5-falling film evaporator, 6-static mixer, 7-gas compressor, 8-first water cooler, 9-circulating pump, 10-discharge pump, 11-first pipeline, 12-second pipeline, 13-third pipeline, 14-fourth pipeline, 15-fifth pipeline. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given below in combination with embodiments and drawings, and the schematic embodiments of the present application and the description thereof are only used to explain the present application, but not to limit the present application.

[0048] All raw materials of the present application are not particularly limited in source, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art. All raw materials of the present application are not particularly limited in purity, and the present application preferably adopts analytical purity or conventional purity requirements in the field of fine chemicals.

[0049] All raw materials of the present application are of conventional grade and abbreviation in the art, and each grade and abbreviation is clear and explicit in its relevant field of use. Those skilled in the art can purchase or prepare them by conventional methods according to the grade, abbreviation and corresponding use.

[0050] Example 1:

[0051] AsFigure 1 The production system for preparing high carbon aldehyde by Fischer-Tropsch synthesis olefin alkyne hydroformylation, comprising:

[0052] a reaction unit for carrying out hydroformylation reaction of raw material olefin, catalyst aqueous solution, and synthesis gas comprising hydrogen and carbon monoxide to obtain a product mixture;

[0053] a separation unit for separating the product mixture to obtain crude aldehyde, catalyst aqueous solution, and tail gas, and delivering the catalyst aqueous solution to the reaction unit;

[0054] a tail gas treatment unit for separating hydrogen in the tail gas, and delivering the hydrogen to the reaction unit;

[0055] wherein the volume ratio of hydrogen to carbon monoxide in the synthesis gas is 1.3-4:1.

[0056] The present embodiment adopts a heterogeneous catalytic system, which can realize rapid separation of catalyst aqueous solution and crude aldehyde in the product mixture, and can significantly improve separation efficiency, prolong catalyst life, and reduce production cost compared to traditional separation of organic phase and aqueous phase by extraction, direct high distillation, etc. The production system comprises three main parts: a reaction unit, a separation unit, and a tail gas treatment unit. As shown in Figure 1 The reaction unit comprises a reactor 1, and raw material olefin after separation and cutting of Fischer-Tropsch synthesis olefin alkyne mixture is subjected to hydroformylation reaction with catalyst aqueous solution and synthesis gas in the reactor 1 under protection of inert atmosphere at high temperature and high pressure to obtain a product mixture. The reactor 1 is in communication with a phase separator 2, and the product mixture is allowed to stand and separate into layers in the phase separator 2, with the lower layer being an aqueous phase and the upper layer being an organic phase, and the upper part of the liquid phase being a gas phase. The main component of the organic phase is crude aldehyde obtained by olefin hydroformylation reaction; the main component of the aqueous phase is catalyst aqueous solution, which can be delivered back to the reactor 1 through a third pipeline 13 and added to the reaction system for recycling; the tail gas of the gas phase comprises unreacted hydrogen, inert gas, water, a small amount of organic matter, etc., and the top of the phase separator 2 is connected to a membrane separation device 3 through a second pipeline 12, and the tail gas is treated by the membrane separation device 3 to obtain hydrogen and release gas, and the hydrogen is delivered back to the reaction unit through a fourth pipeline 14 for recycling as part of the synthesis gas.

[0057] In some preferred embodiments, the separation unit comprises the phase separator 2, and a first water cooler 8 between the phase separator 2 and the reactor 1, the organic phase outlet of the phase separator 2 is connected to an extraction unit through a first pipeline 11, the top of the phase separator 2 is connected to the tail gas treatment unit through a second pipeline 12, and the bottom of the phase separator 2 is connected to the reaction unit through a third pipeline 13.

[0058] In this embodiment, the production system is used for the hydroformylation of Fischer-Tropsch alkenes to prepare higher carbon aldehydes. After separation and cleavage, the Fischer-Tropsch alkenes yield single-carbon hydrocarbon compounds. The α-olefins within these single-carbon hydrocarbon compounds are then directly utilized to produce higher carbon aldehydes via hydroformylation. In some embodiments, the Fischer-Tropsch alkene mixture is selected from C5-C20 alkenes, preferably from C5-C10 alkenes. In one or more embodiments, after separation and cleavage, the mixture of alkenes with the same number of carbon atoms contains 40-80% α-olefins, preferably 65-72% α-olefins, with the remainder being alkanes with the same number of carbon atoms or oxygen-containing hydrocarbons with similar boiling points.

[0059] In one or more embodiments, the syngas may be produced from coal, natural gas or carbon dioxide.

[0060] In this embodiment, the volume ratio of hydrogen to carbon monoxide in the syngas is set to 1.3–4:1, preferably 1.5–3:1. This increases the partial pressure of hydrogen in the reaction system and the amount of hydrogen dissolved in the reaction solution, reducing the formation of polycarbonyl metal rhodium during the reaction and thus inhibiting the loss of rhodium from the catalyst aqueous solution to the organic phase. This ensures that the catalyst aqueous solution maintains good catalytic activity in multiple production cycles. Furthermore, increasing the volume ratio of hydrogen significantly improves the selectivity of straight-chain aldehydes, resulting in more high-carbon straight-chain aldehydes. Preferably, the volume ratio of hydrogen to carbon monoxide in the syngas is 1.5–2.6:1, and more preferably, it is 2–2.6:1.

[0061] In some embodiments, the aqueous catalyst solution comprises a rhodium catalyst, a water-soluble phosphine ligand, and a co-solvent, wherein the rhodium catalyst content is 50–300 ppm, the concentration of the water-soluble phosphine ligand is 6%–10% wt, and the concentration of the co-solvent is 40–70% wt. In some embodiments, the rhodium catalyst is one or more of RhCl3·nH2O, Rh2(CH3COO)4, Rh(acac)(CO)2, and HRh(CO)(TPPTS)3, where acac is an acetylacetone anion. In one or more preferred embodiments, the rhodium catalyst is Rh(acac)(CO)2 and / or HRh(CO)(TPPTS)3. In some preferred embodiments, the water-soluble phosphine ligand is TPPTS, i.e., sodium triphenylphosphine tri-m-sulfonate. In some preferred embodiments, the co-solvent is one or more of methanol, isopropanol, butanol, and liquid polyethylene glycol.

[0062] In some preferred embodiments, the mass ratio of the catalyst aqueous solution to the raw material olefin is 2 to 6:1, preferably 3 to 5:1.

[0063] Example 2:

[0064] Based on Example 1, such as Figure 1 As shown, the reaction unit includes a reactor 1 and a static mixer 6. The static mixer 6 is used to mix the raw material olefin, the catalyst aqueous solution, and the synthesis gas and deliver them to the reactor 1 for hydroformylation reaction.

[0065] Static mixers enhance the dispersion and mixing of the gas-aqueous-organic phases, improving mass transfer between the water and organic phases and facilitating rapid hydroformylation after the reaction system enters the reactor. More importantly, due to the large volume of hydrogen in the syngas, static mixers significantly increase its solubility in the reaction liquid, thereby better suppressing the formation of oil-soluble polycarbonyl rhodium, stabilizing the active species of the rhodium-phosphine complex, and further inhibiting catalyst deactivation and loss into the organic phase. This ensures long-term catalyst stability and lifespan without the need for regeneration or activation processes.

[0066] The static mixer can be an existing static mixer used in industrial production. In one or more embodiments, the static mixer includes a cylinder welded from helical blades, the cylinder having a double channel within which the helical blades are placed. The double channels of adjacent units are offset by 90°, and a fluid redistribution chamber is provided between adjacent units. In some embodiments, the dispersion degree of the static mixer is 1–4 μm.

[0067] Example 3:

[0068] Based on the above embodiments, such as Figure 1 and Figure 2 As shown, the exhaust gas treatment unit includes a membrane separation device 3, which includes a demister 33, a filter 32, and a membrane separator 31 connected in sequence. The demister 33 is connected to the separation unit via a second pipeline 12, and the permeate side of the membrane separator 31 is connected to the reaction unit via a fourth pipeline 14.

[0069] In this embodiment, considering the high hydrogen volume ratio in the synthesis gas, a membrane separation device is used in the tail gas treatment unit to recover excess hydrogen. This device can recover 95% of the hydrogen and recycle it for use in the hydroformylation reaction, effectively reducing production costs and the hydrogen content in the released gas.

[0070] In one or more embodiments, a heater for heating the exhaust gas is provided between the filter and the membrane separator to facilitate hydrogen separation by the membrane separator. A second water cooler is connected to the exhaust end on the permeate side of the membrane separator to reduce the temperature of the hydrogen, and a third water cooler is connected to the exhaust end on the non-permeate side of the membrane separator to reduce the temperature of the released gas.

[0071] In one or more embodiments, a gas compressor is also provided on the fourth pipeline.

[0072] Example 4:

[0073] Based on the above embodiments, such as Figure 1 As shown, the extraction unit includes an extraction tower 4 and a falling film evaporator 5. The extraction tower 4 is used for the crude aldehyde to flow from bottom to top and be mixed countercurrently with the buffer solution flowing from top to bottom for extraction. The extracted aldehyde product is discharged from the top of the extraction tower 4, and the extracted buffer solution is transported to the falling film evaporator 5 from the bottom of the extraction tower 4. The falling film evaporator 5 is used to concentrate the extracted buffer solution. The top of the falling film evaporator 5 is connected to the extraction tower 4, and the bottom of the falling film evaporator 5 is connected to the reaction unit via the fifth pipeline 15.

[0074] In this embodiment, as Figure 3 As shown, the upper layer of crude aldehyde in the phase separator is pumped into the second chamber 42 at the bottom of the extraction tower via the first pipeline, and flows upward in the extraction tower, finally exiting from the top of the extraction tower. The buffer solution, after entering the first chamber 41 at the top of the extraction tower, flows downward and fully contacts and mixes with the crude aldehyde in the packed tower, extracting the catalyst from the crude aldehyde. The extracted buffer solution is transported from the bottom of the extraction tower to the falling film evaporator for concentration via a pipeline. The concentrated heavy component contains rhodium catalyst and can be returned to the reaction unit via the fifth pipeline. The concentrated light component is mainly water, and after removing the buffer pack, it forms a buffer solution, which enters the first chamber 41 of the extraction tower.

[0075] In one or more embodiments, the packing material inside the extraction tower is stainless steel Pall rings.

[0076] In some preferred embodiments, the buffer solution comprises 0.02–0.5% water-soluble phosphine ligand and 0.5–1.5% disodium hydrogen phosphate, and the pH of the buffer solution is 8–9. This buffer solution not only extracts the rhodium catalyst entrained in the crude aldehyde, but the water-soluble phosphine ligand TPPTS in the buffer solution can also coordinate with poorly water-soluble rhodium catalysts such as [HRh(CO)3TPPTS] to form more water-soluble rhodium catalysts such as [HRh(CO)2TPPTS2], further reducing the rhodium catalyst content in the crude aldehyde. Furthermore, maintaining the pH of the buffer solution at 8–9 is beneficial for improving the solubility of the ligand and rhodium catalyst in water; preferably, the pH of the buffer solution is 8.2–8.7.

[0077] Example 5:

[0078] like Figure 4 The Fischer-Tropsch synthesis method for preparing higher carbon aldehydes by hydroformylation of alkenes, using the production system of any of the above embodiments, includes the following steps:

[0079] Under certain pressure and temperature, a reaction system consisting of raw material olefins, catalyst aqueous solution and synthesis gas undergoes a hydroformylation reaction to obtain a mixture of products.

[0080] The product mixture was cooled and allowed to stand for phase separation to obtain crude aldehyde, catalyst aqueous solution and tail gas. The catalyst aqueous solution in the lower layer and the hydrogen in the tail gas were treated and recovered and returned to the reaction system. The crude aldehyde in the upper layer was extracted with buffer solution to obtain product aldehyde.

[0081] After extraction, the buffer solution is concentrated, and the light component is distilled off to form a buffer solution for extracting the crude aldehyde again, while the heavy component at the bottom of the vessel is returned to the reaction system.

[0082] The buffer solution comprises 0.02–0.5% water-soluble phosphine ligand and 0.5–1.5% disodium hydrogen phosphate, and the pH value of the buffer solution is 8–9.

[0083] The hydroformylation reaction is carried out at a temperature of 90–120 °C and a pressure of 1.0–4.0 MPa.

[0084] In this embodiment, the reaction system formed by the raw material olefin, catalyst aqueous solution, and syngas is mixed in a static mixer and then fed into a reactor for hydroformylation to obtain a product mixture. After cooling, the product mixture is allowed to separate into phases in a phase separator. The tail gas enters the tail gas treatment unit, where it is treated by a demister, filter, and membrane separator to recover excess unreacted hydrogen, which is then compressed back into the reaction system as part of the syngas. The lower layer of catalyst aqueous solution is circulated back to the static mixer to contact and mix with the raw material olefin and syngas. The upper layer of crude aldehyde is thoroughly mixed with buffer solution in an extraction tower to further remove the rhodium catalyst from the crude aldehyde, resulting in a high carbon aldehyde with a high positive-to-negative ratio. The extracted rhodium catalyst is concentrated and returned to the reaction system as part of the catalyst aqueous solution. The concentrated light component is then prepared again as buffer solution for cyclic extraction of crude aldehyde.

[0085] In some preferred embodiments, the hydroformylation reaction is carried out at a temperature of 105–110°C and at a pressure of 1.5–2.5 MPa. In some embodiments, the reaction time is 1–6 hours.

[0086] Examples 6 to 8:

[0087] The raw materials for the Fischer-Tropsch synthesis of alkenes and alkanes used in Examples 6-8 are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] The above-mentioned Fischer-Tropsch synthesis mixture of alkenes and alkanes was separated and cut to obtain single-carbon hydrocarbon compounds, as shown in Table 2.

[0092] Table 2

[0093] Table Carbon number Alpha-olefins / % Alkanes / % C5 70.5 27.3 C6 67.3 28 C7 69.8 25.7 C8 71.7 25.2 C9 71.1 25.8

[0094] Example 6:

[0095] Prepare a 10L catalyst aqueous solution with a rhodium content of 250mg / L and a water-soluble ligand concentration of 8%wt. Add 6L of the catalyst aqueous solution to the hydroformylation reactor and 4L to the phase separator. Replace the air with nitrogen and perform pressure testing and leak detection. Then, heat the static mixer to 110℃ using external heating, and maintain the internal temperature of the hydroformylation reactor at 110℃.

[0096] The olefin feedstock contains 71.7% 1-octene and 25.2% octane. The synthesis gas is a mixture of H2:CO in a volume ratio of 2:1, wherein the molar ratio of carbon monoxide to 1-octene is 1.05:1.

[0097] The raw material olefins, synthesis gas, and catalyst aqueous solution are mixed uniformly in a static mixer before entering the hydroformylation reactor. The pressure inside the hydroformylation reactor is controlled at 2.0 MPa by a back pressure valve at the top of the phase separator. After the reaction is completed, the gas-liquid mixture containing high-carbon aldehydes is cooled in a cooler and then enters the phase separator for static phase separation.

[0098] The catalyst aqueous solution in the lower layer of the phase separator is continuously circulated back to the static mixer 6 by the catalyst circulation pump 9 to contact and mix with the raw material olefins and syngas. The organic phase in the upper layer of the phase separator is the obtained high-carbon aldehyde crude aldehyde product. The tail gas at the top of the phase separator enters the membrane separation device to separate and recover excess hydrogen. After passing through the gas compressor 7, it is mixed with the syngas in the static mixer 6. The released gas is an intermittently emitted inert gas.

[0099] Analysis and detection method for hydroformylation reaction tail gas: GC-2000Ⅱ gas chromatograph; Column 1: 2m × 2mm, used to separate inorganic and organic gases in the tail gas into two groups; Column 2: 0.4m × 2mm, used to further separate hydrogen, carbon monoxide, N2 and carbon dioxide, methane, etc., in the inorganic gases; Column 3: 0.25m × 2mm, used to separate alkanes, alkenes, etc., in the organic portion of the tail gas. Column temperature: 65℃; Carrier gas and flow rate: Ar; Flow rate of column 1 and column 3: 20ml / min; Flow rate of column 2: 25ml / min; FID flame ionization detector temperature: 200℃; FID hydrogen flow rate: 25ml / min; FID air flow rate: 350ml / min; TCD thermal conductivity detector temperature: 180℃; TCD thermal conductivity cell current: 70mA.

[0100] The flow rate of the hydroformylation reaction tail gas discharged from the phase separator is 150 L / h, the temperature is 40℃, the pressure is 2.0 MPa, and the hydrogen content is 63.35%. The flow rate of the recovery gas entering the fourth pipeline is 125 L / h, the temperature is 80℃, the pressure is 0.6 MPa, and the hydrogen content is 86.92%. The flow rate of the release gas entering the post-treatment unit is 25 L / h, the temperature is 80℃, the pressure is 1.9 MPa, and the hydrogen content is 16.34%. The calculated hydrogen recovery rate is 95.7%.

[0101] The residence time of the raw material olefin in the reaction device is 90 minutes, the volume flow ratio of the catalyst aqueous solution to the olefin is controlled at 3:1 to 5:1, and the reaction is continuously operated for 48 hours.

[0102] Sampling and analysis of hydroformylation products of Fischer-Tropsch synthesis: The hydroformylation products were identified as the corresponding aldehydes by NMR and high-resolution mass spectrometry. The detection program used Agilent GC-8860 gas chromatograph for quantitative analysis, with an SE-30 capillary column, ψ0.25×30mm, and a flame ionization detector.

[0103] In this embodiment, the conversion rate of 1-octene by hydroformylation was 85%, the selectivity of nonanal reached 88%, and the selectivity of straight-chain aldehydes reached 91%.

[0104] Example 7:

[0105] The difference between this embodiment and Example 6 is that the raw material olefin is a mixture of nonene and alkane, wherein the content of 1-nonene is 71.1% and that of nonane is 25.8%. The hydroformylation reaction pressure is controlled at 1.7 MPa and the reaction is carried out continuously for 48 hours. Sampling analysis shows that the conversion rate of the 1-nonene hydroformylation reaction is 83%, the selectivity of decanal is 87%, and the selectivity of straight-chain aldehydes reaches 95%.

[0106] Example 8:

[0107] The difference between this embodiment and Example 6 is that the raw material olefin is a mixture of pentene and alkane, wherein the content of 1-pentene is 70.5% and pentane is 27.3%, the hydroformylation reaction pressure is controlled at 2.0 MPa, and it is continuously run for 72 hours. Sampling analysis showed that the conversion rate of the 1-pentene hydroformylation reaction was 93%, the selectivity of hexanal was 87%, and the selectivity of straight-chain aldehydes reached 92%.

[0108] Examples 9-15:

[0109] The difference between Examples 9-15, Comparative Example 1 and Example 6 lies in the different volume ratios of hydrogen and carbon monoxide in the synthesis gas. The volume ratios of hydrogen and carbon monoxide were adjusted, and each example / comparative example was run continuously for 12 hours. The rhodium content in the crude aldehyde was analyzed by atomic absorption spectroscopy. The experimental results are shown in Table 3.

[0110] Table 3

[0111]

[0112]

[0113] Table 3 shows that increasing the hydrogen-to-carbon volume ratio in the syngas is beneficial for the formation of straight-chain aldehydes. When the hydrogen-to-carbon volume ratio in the syngas reaches 2.2, the positive-to-negative ratio reaches 19.3, and the selectivity of straight-chain aldehydes reaches 95.1%. Simultaneously, a higher hydrogen-to-carbon volume ratio in the syngas significantly suppresses the loss of rhodium from the catalyst aqueous solution. When the hydrogen-to-carbon volume ratio is greater than 1.5, the rhodium content in the crude aldehyde is only 40–50 ppb. Therefore, in this heterogeneous catalytic system, a higher hydrogen volume ratio allows the Fischer-Tropsch synthesis of alkenes and alkanes to not only produce highly selective straight-chain aldehydes but also effectively suppress the loss of rhodium from the catalyst aqueous solution. Furthermore, excess hydrogen is recovered through a membrane separation device and recycled back to the hydroformylation reactor via a gas compressor to continue the hydroformylation reaction, achieving efficient utilization of syngas, reducing tail gas emissions, further reducing raw material costs, and improving raw material utilization.

[0114] The terms "first," "second," etc., used in this document (e.g., first chamber, second chamber; first pipeline, second pipeline, etc.) are merely for clarity of description and are not intended to restrict any order or emphasize importance. Furthermore, the term "connection" used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

[0115] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the production of higher aldehydes by hydroformylation of Fischer-Tropsch olefins and paraffins, characterized in that, The production method comprises the following steps: a reaction unit for carrying out a hydroformylation reaction of raw material olefin, aqueous catalyst solution and synthesis gas comprising hydrogen and carbon monoxide to obtain a product mixture; a separation unit for separating the product mixture to obtain crude aldehyde, aqueous catalyst solution and tail gas, and conveying the aqueous catalyst solution to the reaction unit; a tail gas treatment unit for separating hydrogen in the tail gas and conveying the hydrogen to the reaction unit; wherein the volume ratio of hydrogen to carbon monoxide in the synthesis gas is 2.2-2.6:1; the aqueous catalyst solution comprises a rhodium catalyst, a water-soluble phosphine ligand and a cosolvent, wherein the content of the rhodium catalyst is 50-300 ppm, the concentration of the water-soluble phosphine ligand is 6%-10%wt, and the concentration of the cosolvent is 40-70%wt, wherein the cosolvent is one or more of methanol, isopropanol, butanol and liquid polyethylene glycol; the tail gas treatment unit comprises a membrane separation device (3) comprising a defoamer (33), a filter (32) and a membrane separator (31) connected in sequence, wherein the defoamer (33) is communicated with the separation unit through a second pipeline (12), and the permeation side of the membrane separator (31) is communicated with the reaction unit through a fourth pipeline (14); the reaction temperature of the hydroformylation reaction is 90-120℃, and the reaction pressure is 1.0-4.0 MPa.

2. The Fischer-Tropsch synthesis olefin / paraffin hydroformylation process for the production of higher aldehydes according to claim 1, characterized in that, The volume ratio of the aqueous catalyst solution to the raw material olefin is 2-6:

1.

3. The Fischer-Tropsch synthesis olefin / paraffin hydroformylation process for the production of higher aldehydes according to claim 1 or 2, characterized in that, The reaction unit comprises a reactor (1) and a static mixer (6), and the static mixer (6) is used for mixing the raw material olefin, the aqueous catalyst solution and the synthesis gas and conveying them into the reactor (1) for the hydroformylation reaction.

4. The Fischer-Tropsch olefin / paraffin hydroformylation process for the production of higher aldehydes according to claim 3, characterized in that, The separation unit comprises a phase separator (2) and a first water cooler (8) located between the phase separator (2) and the reactor (1), the organic phase outlet of the phase separator (2) is connected with an extraction unit through a first pipeline (11), the top of the phase separator (2) is communicated with the tail gas treatment unit through a second pipeline (12), and the bottom of the phase separator (2) is communicated with the reaction unit through a third pipeline (13).

5. The Fischer-Tropsch synthesis olefin / paraffin hydroformylation process for the production of higher aldehydes according to claim 4, characterized in that, The extraction unit comprises an extraction column (4) and a falling film evaporator (5), the crude aldehyde flows from bottom to top in the extraction column (4), is mixed and extracted with a buffer flowing from top to bottom in countercurrent, the extracted product aldehyde is discharged from the top of the extraction column (4), the extracted buffer is conveyed to the falling film evaporator (5) from the bottom of the extraction column (4), the falling film evaporator (5) is used for concentrating the extracted buffer, the top of the falling film evaporator (5) is communicated with the extraction column (4), and the bottom of the falling film evaporator (5) is communicated with the reaction unit through a fifth pipeline (15).

6. The Fischer-Tropsch synthesis olefin / paraffin hydroformylation process for the production of higher aldehydes according to claim 5, characterized in that, The buffer comprises 0.02-0.5% of a water-soluble phosphine ligand and 0.5-1.5% of disodium hydrogen phosphate, and the pH value of the buffer is 8-9.

7. The Fischer-Tropsch synthesis olefin / paraffin hydroformylation process for the production of higher aldehydes according to claim 1, characterized in that, The production method comprises the following steps: under certain pressure and temperature, a reaction system composed of raw material olefin, aqueous catalyst solution and synthesis gas undergoes a hydroformylation reaction to obtain a product mixture; The product mixture is cooled and allowed to separate into a crude aldehyde, a catalyst aqueous solution and tail gas. The hydrogen in the catalyst aqueous solution and tail gas is recovered and returned to the reaction system after treatment. The crude aldehyde is extracted with a buffer solution to obtain the product aldehyde. The buffer solution after extraction is concentrated, and the light components distilled out are used to form a buffer solution for extracting the crude aldehyde again. The heavy components at the bottom of the reactor are returned to the reaction system.

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