A method for separating a catalyst for the carbonylation of propylene to butyraldehyde

Abstract

The present invention provides a method for separating a catalyst for the carbonylation of propylene to butyraldehyde, which relates to the technical field of chemical synthesis. The separation method of the present invention includes: the material after the propylene carbonylation reaction with propylene and syngas as raw materials is subjected to flash separation and evaporation in a low-pressure evaporator, and then a gas-phase material is obtained from the collection tank of the low-pressure evaporator and a liquid-phase catalyst solution is output; the gas-phase material is condensed and subjected to gas-liquid separation to output crude butyraldehyde, and the non-condensable gas is returned to the liquid distribution chamber of the low-pressure evaporator; wherein, the catalyst is triphenylphosphine silicated carbonyl rhodium acetylacetonate, and the operating temperature of the low-pressure evaporator is 85-95 °C. The present invention prevents the catalyst from deactivating at high temperature to extend the service life of the catalyst and reduce the process cost by controlling the circulating air volume and evaporation temperature; the present invention simplifies the process flow and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and particularly relates to a method for separating a catalyst for the carbonylation of propylene to butyraldehyde. Background Art

[0002] Butanol and octanol are important raw materials for organic chemicals, fine chemicals, and chemical auxiliaries, and are widely used in the synthesis of lubricants, solvents, defoamers, additives, antioxidants, etc., as well as in industries such as photography, printing and dyeing, and paper sizing. Both can be produced by the oxo process in the same set of equipment, so they are commonly referred to as butyraldehyde and octanol. The wide range of uses of butyraldehyde and octanol has led to a year-on-year increase in their consumption and production.

[0003] At present, the process of producing butyraldehyde by propylene carbonylation reaction is the most widely used in the production of butyraldehyde and octanol. In this process, using the product n-butyraldehyde as a solvent, propylene and syngas react under the action of a catalyst to produce n-butyraldehyde and isobutyraldehyde. The reaction formula is as follows:

[0004]

[0005] Propane and butanol are by-products in this reaction process. After the reaction is completed, the catalyst is separated from the butyraldehyde solution through an evaporation process, and the separated catalyst can be recycled; the n- / isobutyraldehyde after evaporation and condensation can first be hydrogenated to produce n-butanol and isobutanol, and the n-butanol and isobutanol products are obtained through rectification separation; secondly, the n- / isobutyraldehyde can also be separated into n-butyraldehyde and isobutyraldehyde through an isomerization column. Isobutyraldehyde is used as a by-product, and n-butyraldehyde is condensed and dehydrated under the catalysis of sodium hydroxide to produce octenal, and octenal is hydrogenated to produce crude octanol, and the product octanol is obtained through rectification.

[0006] In the overall process, how to improve the yield and conversion rate of the propylene carbonylation reaction is an important link restricting the scale-up of the butyraldehyde and octanol production process. The key points of the propylene carbonylation process lie in improving the conversion rate of raw materials, reducing the occurrence of side reactions, as well as improving the catalytic efficiency of the catalyst, reducing waste liquid discharge, and reducing energy consumption. For example, a large number of studies have been carried out in these aspects in patents such as CN113041962A, CN117049953A, CN114618396A, CN107759640A, CN117563262A, etc. Among them, the catalyst used in the propylene carbonylation process is an important production cost. In recent years, the separation and recovery of the catalyst from the post-reaction materials have become the research focus in the production of butyraldehyde and octanol. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention discloses a method for separating a catalyst for the carbonylation of propylene to butyraldehyde. During the process of separating the catalyst from the material after the propylene carbonylation reaction, this method can effectively maintain the activity of the catalyst, reduce catalyst loss, and improve process economy; the process flow of this method is simple and is conducive to large-scale industrial production.

[0008] To achieve the above technical objectives, the present invention proposes a method for separating a catalyst for the carbonylation of propylene to butyraldehyde, which includes: the material after the propylene carbonylation reaction using propylene and syngas as raw materials, after flash separation and evaporation in a low-pressure evaporator, a gas-phase material is obtained from the collection tank of the low-pressure evaporator and a liquid-phase catalyst solution is output; the gas-phase material is condensed and subjected to gas-liquid separation to output crude butyraldehyde, and the non-condensable gas is returned to the liquid distribution chamber of the low-pressure evaporator; wherein, the catalyst is triphenylphosphine acetylacetonate rhodium carbonyl silicate, and the operating temperature of the low-pressure evaporator is 85-95 °C.

[0009] In the prior art, the material after the propylene carbonylation reaction is separated from the catalyst and the catalyst solution is returned to the reactor through high- and low-pressure evaporation. The specific process includes: the material after the reaction output from the reaction kettle is input to the top of the high-pressure evaporator, the product butyraldehyde is vaporized and condensed and then enters the propylene absorption tower, and the crude butyraldehyde output from the bottom of the propylene absorption tower enters the stripping tower to separate the propylene and propane dissolved therein to obtain a butyraldehyde product; the catalyst solution concentrated in the high-pressure evaporator is cooled and then enters the low-pressure evaporator, where it is further separated, concentrated, cooled and returned to the reactor. The gas product output from the low-pressure evaporator is condensed and then enters the condensate receiving tank of the low-pressure evaporator. The separated non-condensable gas is discharged to the flare, and the condensate crude butyraldehyde is added to the propylene absorption tower. The overall process involves multiple devices and equipment including a high-pressure evaporator, a propylene absorption tower, a stripping tower, and a low-pressure evaporator. The process flow is relatively complex, the equipment maintenance and repair costs are high, and the pressure of the high-pressure evaporator is generally about 0.7 MPa, which easily causes the catalyst to deactivate.

[0010] The above technical solution uses a specific rhodium acetylacetonate triphenylphosphine silylcarbonyl to catalyze the carbonylation of propylene. After the reaction, the unreacted raw materials can be separated through a flash separation process. This part of the raw materials will return to the upstream reaction process after condensation and separation; this process not only simplifies the equipment, but also the operating pressure of the flash process is lower than that of the high-pressure evaporator, which is beneficial to maintaining the catalytic activity of the catalyst. In addition, the liquid-phase material obtained by flash separation is a concentrated catalyst solution. After this part of the material is further concentrated by a low-pressure evaporator, the obtained catalyst solution can be directly returned to the upstream reaction process for recycling after condensation; the gas-phase material obtained by low-pressure evaporation is condensed and separated by gas-liquid separation, and the obtained non-condensable gas is input into the liquid distribution chamber at the upper part of the low-pressure evaporator as circulating gas, thereby promoting the reduction of the liquid film thickness in the low-pressure evaporator to accelerate evaporation, and at the same time reducing and controlling the evaporation temperature to 85-90 °C, which can prevent the rhodium acetylacetonate triphenylphosphine silylcarbonyl catalyst from deactivating at high temperatures and extend the service life of the catalyst; the recycling and utilization of non-condensable gas is environmentally friendly and energy consumption is saved; the liquid-phase material obtained by the second gas-phase condensation and gas-liquid separation is crude butyraldehyde.

[0011] The above technical solution simplifies the equipment, is easier to operate, can improve the operating efficiency of the low-pressure evaporator and obtain a higher liquid output, and can reduce the supplement amount of the overall process catalyst in the actual process, that is, extend the service life of the catalyst and further reduce the process cost of propylene carbonylation. The examples and comparative examples of the present invention illustrate the operating technical effects of the above technical solution.

[0012] In a further example of the present invention, the control conditions of the catalyst, the operation of the low-pressure evaporator, the flash separation operation, etc. in the above technical solution were explored to optimize the overall process effect.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses a flash separation process combined with a low-pressure evaporation process to separate the products and the catalyst in the material after the propylene carbonylation reaction. By circulating the non-condensable gas obtained by low-pressure evaporation to the liquid distribution chamber of the low-pressure evaporator, the efficiency of low-pressure evaporation is improved by controlling the circulating air volume and evaporation temperature, and thereby the evaporation temperature of the low-pressure evaporation is reduced, further preventing the catalyst from deactivating at high temperatures and extending the service life of the propylene carbonylation reaction catalyst, and reducing the process cost. The present invention simplifies the high- and low-pressure evaporation equipment of the traditional propylene carbonylation reaction, has stronger operability, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1A structural diagram showing a catalyst separation method for the carbonylation of propylene to butyraldehyde according to the present invention is presented.

[0016] Among them, the above-mentioned drawings include the following reference numerals:

[0017] 1 - Flash tank, 2 - Separation tank, 3 - Low-pressure evaporator, 4 - Collection tank, 5 - Condensate receiving tank, 6 - Compressor. Detailed implementation manners

[0018] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.

[0019] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0020] The present invention provides a catalyst separation method for the carbonylation of propylene to butyraldehyde. The method includes the material after the propylene carbonylation reaction using propylene and syngas as raw materials. After flash separation and evaporation in the low-pressure evaporator 3, the gas-phase material is obtained from the collection tank 4 of the low-pressure evaporator 3 and the liquid-phase catalyst solution is output; the gas-phase material is condensed and separated by gas-liquid to output crude butyraldehyde, and the non-condensable gas is returned to the liquid distribution chamber of the low-pressure evaporator 3; among them, the catalyst is triphenylphosphine silicated carbonyl rhodium acetylacetonate, and the operating temperature of the low-pressure evaporator 3 is 85 - 95 °C.

[0021] Figure 1 A structural diagram showing a catalyst separation method for the carbonylation of propylene to butyraldehyde according to the present invention is presented. As Figure 1As shown, the material after the propylene carbonylation reaction is fed into the flash tank 1 for flash separation. After flash concentration, the gaseous material is output from the gas outlet of the flash tank 1, condensed by the condenser and then undergoes gas-liquid separation in the separation tank 2. Unreacted raw materials (such as propylene, syngas, etc.) are separated as gas phase and returned to the upstream reaction process for recycling. The obtained liquid phase is a solution containing butyraldehyde; the liquid phase material obtained after flash evaporation in the flash tank 1 is fed into the low-pressure evaporator 3 for further evaporation; the gaseous material obtained from the collection tank 4 of the low-pressure evaporator 3 is condensed by the condenser and then fed into the condensate receiving tank 5 for gas-liquid separation. The obtained non-condensable gas will be returned to the liquid distribution chamber above the low-pressure steam to regulate the efficiency of low-pressure falling film evaporation. At the same time, it can promote the regulation and reduce the temperature of low-pressure evaporation, avoid the inactivation of the catalyst due to high temperature, thereby prolonging the service life of the catalyst and saving process costs; the liquid phase obtained from the gas-liquid separation in the condensate receiving tank 5 is crude butyraldehyde, and this crude butyraldehyde will be fed into the downstream for subsequent treatment. The liquid phase material obtained from the collection tank 4 of the low-pressure evaporator 3 is a catalyst solution, and this catalyst solution can be directly returned to the upstream reaction process and / or a part of it is fed into the downstream catalyst washing process, etc., to realize the recycling of the catalyst.

[0022] Optionally, the catalyst is prepared by the following method: S1, methanol is added to an aqueous solution of rhodium trichloride with a concentration of 25wt%-30wt%, and the volume addition amount of methanol is 5-10 ml / g based on the mass of rhodium trichloride; S2, the reaction solution in step S1 is heated to 40-50 °C, then carbon monoxide is introduced, and stirring is carried out for 3-8 h; S3, sodium acetylacetonate is added to the reaction solution and stirred for reaction, and the molar ratio of sodium acetylacetonate to rhodium element is (3-5):1; then triphenylphosphine and an organosilicon compound are added, and after reacting for 2-4 h, the rhodium carbonyl silicated triphenylphosphine acetylacetonate is obtained; wherein, the mass ratio of triphenylphosphine, the organosilicon compound to the rhodium element is (5-8):(2-5):1, and the organosilicon compound is octaphenylcyclotetrasiloxane or triisopropylsilane.

[0023] On the premise of fully considering the influence of the electronic effect and steric hindrance effect of the transition metal and phosphorus-containing ligand in the catalyst on the catalytic effect, in order to improve the activity and stability of the reaction (i.e., increase the reaction conversion rate), and the selectivity of the reaction (i.e., increase the reaction yield), while selecting rhodium as the transition metal in the catalytic system, silicon element is introduced into the phosphorus-containing ligand. Its electronegativity is weaker, its volume is larger, and it has 3d empty orbitals, which can accept electrons to form coordination, making the catalytic system have a stronger electronic effect; the conversion rate of the propylene carbonylation reaction catalyzed by the acetylacetonetri(phenylphosphine)siliconylrhodium catalyst is greater than 96.8%, and the yield is greater than 95.7%. In addition, the acetylacetonetri(phenylphosphine)siliconylrhodium catalyst efficiently catalyzes the propylene carbonylation reaction within the temperature control range of 70-90 °C. The lower catalytic temperature can reduce the operating energy consumption of the process and save the process cost.

[0024] Further optionally, the preparation method of the catalyst further includes: S4, after cooling the reaction material in step (3), filtering, and drying the obtained filter cake after washing to obtain the acetylacetonetri(phenylphosphine)siliconylrhodium product. In the washing operation, deionized water, an alcohol solvent (such as ethanol), or a hydrocarbon solvent (such as n-hexane) can be optionally used for washing; low-temperature drying, vacuum drying, or other drying methods can be optionally used for the drying operation.

[0025] The present invention optimizes the operating temperature of the low-pressure evaporator 3 based on a large amount of experimental data. Optionally, the operating temperature of the low-pressure evaporator 3 is 85 °C. At this operating temperature, it is beneficial to maintain the activity of the catalyst, increase the liquid output of the low-pressure evaporator 3, and improve the separation efficiency.

[0026] Optionally, the operating pressure of the low-pressure evaporator 3 is 65-70 kPa. By optimizing the operating pressure of the low-pressure evaporator 3, it can synergistically promote the control of the operating temperature of the low-pressure evaporator 3, which is beneficial to reducing the evaporation temperature, improving the separation efficiency, and saving energy consumption.

[0027] Optionally, the non-condensable gas is compressed by the compressor 6 and then returned to the liquid distribution chamber of the low-pressure evaporator 3. Among them, the circulating air volume per unit output of the crude butyraldehyde is 45-195 Nm³ / h·t, that is, the circulating air volume per output of 1 ton of the crude butyraldehyde is 45-195 Nm³ / h; preferably 95-195 Nm³ / h, and more preferably 140-160 Nm³ / h. Figure 1 An example is shown in which the non-condensable gas is compressed by the compressor 6 and then returned to the low-pressure evaporator 3.

[0028] Optionally, in order to facilitate maintaining the pressure of the low-pressure evaporator 3, in actual operation, a part of the non-condensable gas can be circulated back to the low-pressure evaporator 3 to facilitate regulating the circulation amount of the non-condensable gas, and further regulating the low-pressure evaporation efficiency; the exhausted non-condensable gas can be optionally connected to the fuel gas pipeline network or input into other processes.

[0029] Optionally, based on a large amount of experimental data, the evaporation capacity of the low-pressure evaporator 3 is 31.05 - 31.3 t / h. By returning the non-condensable gas, the operating temperature of the low-pressure evaporator 3 can be regulated to a lower and appropriate control range. At the same time, a higher evaporation capacity of the low-pressure evaporator 3 (the output of crude butyraldehyde) can be obtained, improving the catalyst separation efficiency of the overall method.

[0030] Optionally, the flash separation process is carried out in the flash tank 1 for separating unreacted raw materials from the post-reaction materials; the gaseous materials obtained by flashing are unreacted raw materials, which are output from the gas phase outlet of the flash tank 1, condensed, separated, and then returned to the upstream reaction process; the liquid materials obtained by flashing are input into the low-pressure evaporator 3; wherein, the operating pressure of the flash tank 1 is 0.4 - 0.45 MPa, and the operating temperature is 75 - 85 °C; the optimization of the flash pressure in the present invention can increase the evaporation rate. Controlling the flash pressure and temperature within an appropriate range can regulate the concentration effect and prevent overheating from damaging the activity of the catalyst.

[0031] Further optionally, the heating temperature of the flash tank 1 is 120 - 124 °C; further optionally, combined with Figure 1 , after the gaseous materials obtained by flashing are condensed, gas-liquid separation is carried out in the separation tank 2, and the unreacted materials are output from the gas phase outlet of the separation tank 2. Further optionally, a first branch for discharging purge gas is provided on the pipeline connecting the gas phase outlet of the separation tank 2. Through the first branch, part of the by-products and unreacted substances, such as propane, propylene, etc., can be discharged in due time and in appropriate amounts, which is beneficial to the regulation of the upstream reaction process and the effective recovery of propylene and the reduction of the accumulation of propane in the overall process route; further optionally, the first branch can be optionally connected to the fuel gas pipeline network or other processes.

[0032] The propylene carbonylation reaction described in the present invention includes the reaction of propylene with syngas under the action of a catalyst to obtain butyraldehyde. Optionally, in the propylene carbonylation reaction, the feed molar ratio of propylene to syngas is 1:(2 - 3), and the molar ratio of hydrogen to carbon monoxide in the syngas is 1:(1 - 1.05); the concentration of the catalyst is 15 - 25 ppm. Optionally, the reaction temperature of the propylene carbonylation reaction is 70 - 90 °C, and the reaction pressure is 1.5 - 1.8 MPa.

[0033] It should be noted that in the present invention, the material after the propylene carbonylation reaction is fed into the upper part of the low-pressure evaporator 3 and input into the liquid distribution chamber; in the liquid distribution chamber, the material to be evaporated is evenly distributed onto the surfaces of the downcomers in the evaporation chamber to promote uniform falling film, thereby helping to improve the heat exchange efficiency and prevent local overheating.

[0034] It should be noted that the present invention does not limit the specific structures of the equipment such as the flash tank 1, the separation tank 2, the collection tank 4, and the condensate receiving tank 5. They can be selected as container-type equipment, and further can be equipment provided with a demister and a butyraldehyde circulation spray pipe at the top of the container, so as to effectively prevent the loss of the catalyst during the separation process; the present invention does not limit the specific structure of the used low-pressure evaporator 3. It can be selected as an effective thin-film forming vertical falling film evaporator. Those skilled in the art can select flash tanks 1, separation tanks 2, collection tanks 4, condensate receiving tanks 5, and low-pressure evaporators 3 with appropriate structures according to needs, and this does not limit the protection scope of the present invention.

[0035] Example 1

[0036] This example shows the process of a catalyst separation method for the production of butyraldehyde from propylene carbonylation under specific working conditions. It should be noted that this implementation is only a better demonstration and does not limit the protection scope of the present invention.

[0037] Specifically, in the reaction process, 20.722 t / h of propylene is input into the reactor. The molar ratio of propylene to syngas is 1:2, and the molar ratio of hydrogen to carbon monoxide in the syngas is 1:1.05; n-butyraldehyde is used as the solvent, and the catalyst used is tris(triphenylphosphine)rhodium carbonyl silicate acetylacetonate. The reaction temperature is 70 - 90 °C, and the reaction pressure is 1.5 - 1.8 MPa; the material after the reaction is completed contains propylene, propane, n-butyraldehyde, isobutyraldehyde, additives, trimers, etc., with a pressure of 1.5 MPa and a temperature of 80 °C.

[0038] The preparation method of the tris(triphenylphosphine)rhodium carbonyl silicate acetylacetonate catalyst is as follows:

[0039] S1, Add methanol to the 28 wt% rhodium trichloride aqueous solution. The volume addition amount of methanol is 8 ml / g based on the mass of rhodium trichloride.

[0040] S2, Heat the reaction solution in step S1 to 40 - 50 °C, then introduce carbon monoxide, stir, and maintain for 6 h.

[0041] S3, Then add sodium acetylacetonate to the reaction solution and stir to react. The molar ratio of sodium acetylacetonate to rhodium element is 4:1; then add triphenylphosphine and triisopropylsilane. The mass ratio of triphenylphosphine, organosilicon compound to rhodium element is 6.7:3.3:1. After reacting for 2 - 4 h, the tris(triphenylphosphine)rhodium carbonyl silicate acetylacetonate is obtained.

[0042] After the reaction material passes through the flash tank 1 for flashing, the obtained gas-phase material is condensed and separated and then returned to the upstream reaction process, and the obtained liquid-phase material is input into the low-pressure evaporator 3. Among them, the operating pressure of the flash tank 1 is 0.45 MPa, the temperature is 80 °C, and a concentrated catalyst solution with an outlet pressure of 1.2 - 1.5 MPa is output from the flash tank 1, and this part of the solution is input into the low-pressure evaporator 3.

[0043] In this embodiment, the operating temperature of the low-pressure evaporator 3 is 95 °C, the circulating air volume of the compressor 6 connected to its top is 1500 Nm³ / h, and the evaporation amount (the amount of the output catalyst solution) of the low-pressure evaporator 3 is 31.3 t / h. By recycling the separated catalyst solution subsequently, the supplementary amount of the catalyst in this embodiment is 115 g / week.

[0044] Examples 2 - 10

[0045] Based on the catalyst separation method for the carbonylation of propylene to butyraldehyde shown in Example 1, the catalyst separation processes for the carbonylation of propylene to butyraldehyde under different working conditions are shown in Examples 2 - 10. The technological processes and parameter controls of these examples are the same as those of Example 1, except that different circulating air volumes of the compressor 6 and operating temperatures of the low-pressure evaporator 3 are adopted. Table 1 shows the specific parameter control ranges, evaporation amounts, and catalyst supplementary amounts of Examples 2 - 10.

[0046] Comparative Example 1

[0047] This comparative example shows a catalyst separation method for the material after the carbonylation reaction of propylene to butyraldehyde. This method is the same as the technological process and parameter control of Example 1, except that the non-condensable gas separated from the condensate receiving tank 5 is not returned to the liquid distribution chamber of the low-pressure evaporator 3 in this comparative example. The specific evaporation temperature, evaporation amount, and catalyst supplementary amount are shown in Table 1.

[0048] Table 1

[0049]

[0050] The optimal catalytic temperature of the catalyst used in this embodiment is 70-90°C. During the separation process of the materials after the propylene carbonylation reaction to produce butyraldehyde, if the separation temperature is higher than 95°C, it may cause the inactivation of the catalyst. It can be confirmed from Table 1 that when the evaporation amount of the low-pressure evaporator 3 is the same, the evaporation temperature of Comparative Example 1 without the non-condensable gas circulation technical feature reaches 98°C, which is significantly higher than the control temperature of 85-95°C in Examples 1-10; further, it is found during the recycling of the catalyst solution that the supplementary amount of the catalyst in Comparative Example 1 is higher than that in the technical solutions of Examples 1-10, which proves that the separation of the catalyst at a higher temperature in Comparative Example 1 destroys the activity of the catalyst and reduces the overall service life of the catalyst. And the supplementary amount of the catalyst in the embodiment of the present invention is significantly lower than that in Comparative Example 1. Considering that the preparation cost of the catalyst using rhodium element as the active component in the propylene carbonylation reaction is relatively high, the technical solution of the present invention has better economic benefits, which will play an important advantage in large-scale industrial production.

[0051] In addition, by analyzing Examples 1-10, it can be confirmed that when the circulating air volume of the compressor 6 is controlled at 1500-6000 Nm³ / h for production, that is, the circulation volume is 45-195 Nm³ / h·t relative to the unit of the crude butyraldehyde (evaporation amount), and the operating temperature of the low-pressure evaporator 3 is 85-95°C, the evaporation amount of the low-pressure evaporator 3 can be effectively guaranteed to reach 31.05-31.3 t / h, and the weekly supplementary amount of the catalyst can be controlled within 110 g; combined with the simpler equipment and process flow of the present invention compared with the prior art, the catalyst separation method for propylene carbonylation to produce butyraldehyde of the present invention has excellent operability and economy. Further, when the air volume of the compressor 6 is controlled at 3000-6000 Nm³ / h, that is, the circulation volume is 95-195 Nm³ / h·t relative to the unit of the crude butyraldehyde (evaporation amount), the evaporation temperature can be reduced and controlled at 85-90°C (such as Examples 4-10), which is more conducive to maintaining the activity of the catalyst. At this time, the evaporator can still maintain a relatively high evaporation amount and the weekly supplementary amount of the catalyst can be maintained within 112 g / week. When the air volume of the compressor 6 is controlled above 4500 m³ / h, the evaporation temperature can be reduced and controlled at about 85°C (such as Examples 7-10), which is more conducive to maintaining the activity of the catalyst. At this time, the evaporator can still maintain a relatively high evaporation amount and the weekly supplementary amount of the catalyst can be maintained within 110 g / week; surprisingly, when the circulating air volume rises above 4500 Nm³ / h, the evaporation temperature is maintained at 85°C, the supplementary amount of the catalyst no longer decreases, but the evaporation amount shows a gradually decreasing trend. Therefore, for economic consideration, the circulating air volume of the compressor 6 in the technical solution of the present invention is more preferably set at 4500-5000 Nm³ / h, that is, the circulation volume is 140-160 Nm³ / h·t relative to the unit of the crude butyraldehyde (evaporation amount), and the operating temperature of the low-pressure evaporator 3 is 85°C.

[0052] It should be noted that the above content is a further detailed description of the present invention in combination with specific implementation manners, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple improvements can still be made, and all should be regarded as belonging to the scope of protection of the present invention.

Claims

1. A method for separating a catalyst for carbonylation of propylene to butyraldehyde, characterized in that: The material after propylene carbonylation reaction with propylene and synthesis gas as raw materials is flash separated and evaporated in a low-pressure evaporator, and a gas phase material is obtained from the collecting tank of the low-pressure evaporator and a liquid phase catalyst solution is output; the gas phase material is condensed and separated into gas and liquid, and crude butyraldehyde is output, and the non-condensable gas is returned to the liquid distribution chamber of the low-pressure evaporator; wherein the catalyst is triphenylphosphosiliconate carbonyl rhodium acetylacetonate, and the operating temperature of the low-pressure evaporator is 85-95°C; The catalyst is prepared by the following preparation method: S1, adding methanol to a 25wt%-30wt% aqueous solution of rhodium trichloride, wherein the volume of methanol added is 5-10mL / g based on the mass of rhodium trichloride; S2, heating the reaction solution of step S1 to 40-50°C, then introducing carbon monoxide, stirring, and maintaining for 3-8 hours; S3, adding sodium acetylacetone to the reaction solution and stirring for reaction, wherein the molar ratio of the sodium acetylacetone to the rhodium element is (3-5):1; then adding triphenylphosphine and an organosilicon compound, reacting for 2-4 hours to obtain the acetylacetonate triphenylphosphine carbonyl rhodium; The mass ratio of triphenylphosphine, organosilicon compound and rhodium element is (5-8): (2-5): 1, and the organosilicon compound is octaphenylcyclotetrasiloxane or triisopropylsilane; The operating pressure of the low-pressure evaporator is 65-70 kPa; the non-condensable gas is compressed by the compressor and returned to the liquid distribution chamber of the low-pressure evaporator, wherein the circulating air volume for each ton of the crude butyraldehyde output is 45-195 Nm³ / h.

2. The method for separating the catalyst for carbonylation of propylene to butyraldehyde according to claim 1, characterized in that: The operating temperature of the low-pressure evaporator is 85-90°C.

3. The method for separating the catalyst for carbonylation of propylene to butyraldehyde according to claim 1, characterized in that: A portion of the non-condensable gas is input into the gas pipeline network.

4. The method for separating the catalyst for preparing butyraldehyde by carbonylation of propylene according to claim 1, characterized in that: The evaporation capacity of the low-pressure evaporator is 31.05-31.3 t / h.

5. The method for separating the catalyst for preparing butyraldehyde by carbonylation of propylene according to claim 1, characterized in that: The flash separation process is carried out in a flash tank, which is used to separate unreacted raw materials from the reacted materials; the gaseous material obtained by flash evaporation is the unreacted raw material, which is output from the gas phase outlet of the flash tank, condensed, separated and returned to the upstream reaction process; the liquid material obtained by flash evaporation is input into the low-pressure evaporator; wherein the operating pressure of the flash tank is 0.4~0.45MPa, and the operating temperature is 75~85°C.

6. The method for separating the catalyst for preparing butyraldehyde by carbonylation of propylene according to claim 1, characterized in that: The feed molar ratio of propylene to synthesis gas in the propylene carbonylation reaction is 1:(2-3), the molar ratio of hydrogen to carbon monoxide in the synthesis gas is 1:(1-1.05); and the concentration of the catalyst is 15-25 ppm.

7. The method for separating the catalyst for carbonylation of propylene to butyraldehyde according to claim 6, characterized in that: The reaction temperature of the propylene carbonylation reaction is 70-90° C., and the reaction pressure is 1.5-1.8 MPa.

Images