An energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step

Abstract

The present invention discloses an energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step. The present invention proposes a new distillation process for a six-tower distillation process of a one-step MIBK production device for acetone using a Pd-loaded cation exchange resin catalyst, which reduces one extraction tower and one MIBK light component tower; from the process point of view, the present invention greatly simplifies the process; from the cost point of view, the present invention saves the construction cost of two towers; from the energy consumption point of view, the present invention can save the steam consumption of a reboiler of a MIBK light component tower, saving energy and reducing consumption; from the control point of view, the present invention cancels the MIBK light component tower that is most prone to fluctuations, making the entire distillation system more stable and easier to control.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production processes, and in particular to an energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step. Background Art

[0002] Methyl isobutyl ketone (MIBK) is a colorless, stable, and widely used medium-boiling-point solvent. It is mainly used as a solvent for nitrocellulose, polyvinyl chloride, polyvinyl acetate, polystyrene, epoxy resin, natural and synthetic rubber, paint, coating, and degreasing, and a colorant for color film. It is also used as an extractant for penicillin fermentation broth and a separator for some organic salts. It is also the main raw material for rubber antioxidant 4020 and some organic syntheses. Because it has a wide range of applications, it has a huge market demand.

[0003] At present, the mainstream process technology for synthesizing MIBK is the acetone one-step method, and the distillation process used by most chemical companies that use the acetone one-step method to produce MIBK is a six-tower distillation process (until the product MIBK is obtained). For example, the Chinese patent application number 201510551606.9 "A Production Process for Methyl Isobutyl Ketone" provides a typical distillation process for synthesizing MIBK from acetone in one step, such as Figure 1 As shown, the process comprises the following steps: a. the product solution after adding alkali enters into an acetone light component tower for separation, the output solution at the bottom of the tower enters into an acetone recovery tower for rectification, the acetone recovery tower is operated under negative pressure, the output acetone at the top of the tower is recycled into a fixed bed reactor, the output crude MIBK at the bottom of the tower enters into a phase separator for separation of crude MIBK and aqueous phase, the separated crude MIBK enters into a downstream process for further separation, and the aqueous phase enters into an acetone dehydration tower for dehydration; b. the crude MIBK enters into a MIBK light component tower for rectification, water and isopropanol are output from the top of the tower, water-rich products are output from the side line of the tower, heavy components are output from the bottom of the tower, the heavy components enter into a finished MIBK tower for purification, and the finished MIBK tower side line outputs finished MIBK. In addition, the Chinese patent application number 201310151579.7, "A Methyl Isobutyl Ketone Production Process and Equipment", provides a relatively simple distillation process designed for the new crude product composition after the use of a new catalyst B621, such as Figure 2As shown, it includes the following steps: a. The product solution is sent to the light component tower for separation, and the bottom kettle liquid enters the acetone tower for separation; b. The acetone tower pressure is controlled to be slightly negative pressure, and the heavy component obtained at the bottom of the tower is sent to the dehydration tower for dehydration; c. The light component obtained at the top of the dehydration tower is sent to the wastewater tower for treatment to obtain an organic light component; the product obtained at the bottom of the dehydration tower is sent to the product tower for purification, and the product methyl isobutyl ketone is obtained at the top of the product tower. The distillation process provided by the above two patents is that the former has a lengthy process, high energy consumption, difficult control, and easy fluctuations, which affects the purity of the product; the latter has more by-products, high operating temperature and pressure, high energy consumption and material consumption, and the latter distillation process is only applicable to the reaction unit using B621 catalyst, while the catalyst used by most MIBK manufacturers is Pd-loaded cation exchange resin. Therefore, for most MIBK manufacturers, these patents do not have reference significance for technical transformation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the technical defects of the existing one-step acetone MIBK distillation process and provide an energy-saving one-step acetone MIBK distillation process. The present invention provides a MIBK distillation process method suitable for MIBK manufacturers using a Pd-loaded cation exchange resin catalyst, which has a simple process, low energy consumption, convenient control and high safety.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] An energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step comprises the following steps:

[0007] (1) The crude product from the acetone one-step reaction unit first enters a light-removal tower, which is an extractive distillation tower. The extractant is water, and the extractant comes from the aqueous phase of the phase separator of the acetone removal tower. The extractive distillation solves the azeotropic problem of 2-methylpentane and acetone. Acetone no longer leaves the top of the light-removal tower with 2-methylpentane. At this time, the top of the light-removal tower is an azeotropic mixture of 2-methylpentane and water, and the top material is subsequently sent to the phase separator. Since water and 2-methylpentane are completely immiscible, the organic phase after phase separation is 2-methylpentane with a purity of 99.8%, which can be directly sold as a by-product. The aqueous phase is water with a low organic matter content, which is directly sent to wastewater treatment. The bottom liquid of the light-removal tower is sent to the acetone removal tower.

[0008] (2) The bottom liquid of the light-removal tower is sent to the deacetone tower for rectification; acetone with a purity of 99.5% is taken out from the top of the deacetone tower, and the acetone is recycled to the reaction unit to continue to participate in the reaction; a phase separator is provided in the middle of the stripping section of the deacetone tower to draw out all the liquid phase in the tower and introduce it into the phase separator for phase separation. After phase separation, the organic phase returns to the tower, and part of the water phase is cooled by the cooler and refluxed to the light-removal tower as an extractant, and the remaining water phase is sent to the dehydration tower; the mass fraction of water in the middle of the stripping section of the deacetone tower is relatively high, so after phase separation, from the perspective of material balance, The water sent into the distillation system can be completely discharged; in addition, since a large amount of water is discharged, the azeotropic reaction of water and isopropanol (azeotropic temperature 80°C) and water and MIBK (azeotropic temperature 88°C) can be greatly reduced, so that the isopropanol, water and MIBK that were previously difficult to separate can now be well separated; therefore, the discharge from the bottom of the deacetone tower is MIBK and other heavier components, and all isopropanol leaves with the water phase of the phase separator; the bottom liquid of the deacetone tower can be directly sent to the MIBK product tower for distillation and separation to obtain the MIBK product;

[0009] (3) The bottom liquid of the acetone removal tower is sent to the MIBK product tower for rectification; a MIBK product with a purity of 99.5% is taken out from the top of the MIBK product tower, and heavy components are taken out from the bottom of the tower;

[0010] (4) Part of the water phase from the acetone removal tower is sent to a dehydration tower for dehydration; the top of the dehydration tower is a mixture of organic light components, and the bottom of the tower is water with a low organic content, which is sent to wastewater treatment.

[0011] Preferably, in step (1), the acetone one-step method uses a Pd-loaded cation exchange resin as a catalyst.

[0012] Preferably, in step (1), the crude reaction product comprises acetone, MIBK, water, 2-methylpentane, isopropanol, diisobutyl ketone, mesitylene, mesitylene oxide, and oligomers.

[0013] More preferably, the crude reaction product comprises, by mass percentage, 69.98% to 70.60% acetone, 22.18% to 22.75% MIBK, 5.32% to 5.50% water, 0.31% to 0.34% 2-methylpentane, 0.42% to 0.46% isopropanol, 0.38% to 0.45% diisobutyl ketone, 0.50% to 0.83% mesitylene, 0.01% to 0.02% mesityl oxide, and 0.03% to 0.06% oligomers.

[0014] Preferably, in step (1), the light-removal tower is operated at normal pressure, the top pressure is 0-10 KPaG, the top temperature is 37-42°C, the bottom pressure is 23-35 KPaG, and the bottom temperature is 65-72°C.

[0015] Preferably, in step (2), the deacetone tower is operated at negative pressure, the tower top pressure is -35 to -25 KPaG, the tower top temperature is 44 to 50°C, the tower bottom pressure is -10 to 0 KPaG, and the tower bottom temperature is 112 to 118°C.

[0016] Preferably, in step (2), 41.0 wt% to 42.0 wt% of the aqueous phase is cooled in a cooler and then refluxed to the lightness removal tower as an extractant, and the remaining aqueous phase is sent to a dehydration tower.

[0017] More preferably, 41.0 wt% to 42.0 wt% of the water phase is cooled to 38 to 39° C. in a cooler and then refluxed to the lightness removal tower as an extractant.

[0018] Preferably, in step (3), the MIBK product tower is operated at normal pressure, the top pressure is 0-10 KPaG, the top temperature is 115-120°C, the bottom pressure is 15-29 KPaG, and the bottom temperature is 168-178°C.

[0019] Preferably, in the step (3), the bottoms liquid of the MIBK product tower is sent to a DIBK tower to recover diisobutyl ketone DIBK.

[0020] Preferably, in step (4), the dehydration tower is operated at normal pressure, the top pressure is 0-10 KPaG, the top temperature is 75-85°C, the bottom pressure is 3-15 KPaG, and the bottom temperature is 100-105°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Most of the existing distillation processes for synthesizing methyl isobutyl ketone (MIBK) from acetone in one step are too lengthy. Although a small part of the distillation processes are relatively simple, they are only for the new B621 catalyst and are not suitable for the current mainstream production device using a Pd-loaded cation exchange resin catalyst. The present invention proposes a new distillation process for a six-tower distillation process of an acetone one-step MIBK production device using a Pd-loaded cation exchange resin catalyst, thereby reducing one extraction tower and one MIBK light component tower. From the perspective of the process, the present invention greatly simplifies the process. From the perspective of cost, the present invention saves the construction cost of two towers. From the perspective of energy consumption, the present invention can save the steam consumption of a reboiler of a MIBK light component tower, thereby saving energy and reducing consumption. From the perspective of control, the present invention cancels the MIBK light component tower which is most prone to fluctuations, thereby making the entire distillation system more stable and easier to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the distillation process flow chart of the existing mainstream acetone one-step method to synthesize MIBK;

[0024] Figure 2 This is a distillation process flow chart for synthesizing MIBK from acetone in one step using B621 catalyst;

[0025] Figure 3 The distillation process flow chart of energy-saving acetone one-step synthesis of MIBK in Examples 1 to 3 of the present invention is shown. DETAILED DESCRIPTION

[0026] In order to better understand the content of the present invention, further description is given below in conjunction with specific embodiments and accompanying drawings. It should be understood that these embodiments are only used to further illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content described in the present invention, those skilled in the art may make some non-essential changes or adjustments to the present invention, which still belong to the protection scope of the present invention.

[0027] Example 1

[0028] An energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step, such as Figure 3 As shown, the following steps are included:

[0029] (1) The crude product of the reaction from the acetone one-step reaction unit using a Pd-supported cation exchange resin as a catalyst (composition: 70.32 wt% of acetone, 22.18 wt% of MIBK, 5.50 wt% of water, 0.31 wt% of 2-methylpentane, 0.42 wt% of isopropanol, 0.38 wt% of diisobutyl ketone, 0.83 wt% of mesitylene, 0.02 wt% of mesityl oxide, and 0.04 wt% of oligomers) first enters a lightness removal column, which is an extractive distillation column. The extractant is water, which is derived from the aqueous phase of the phase separator of the acetone removal column. The lightness removal column is operated at normal pressure, and the top pressure is 3.5 KPaG. The top temperature is 38.5°C, the bottom pressure is 26.5KpaG, and the bottom temperature is 68.3°C; the extractive distillation solves the azeotropic problem of 2-methylpentane and acetone, and acetone no longer leaves the top of the light-removing tower with 2-methylpentane. At this time, the top of the light-removing tower is an azeotropic mixture of 2-methylpentane and water (mainly composed of 96.77wt% of 2-methylpentane, 3.05wt% of water, 0.12wt% of isopropanol, 0.04wt% of acetone, and MIBK 0.02wt%), and the top material is subsequently sent to a phase separator; since water and 2-methylpentane are completely immiscible, the organic phase after phase separation is 2-methylpentane with a purity of 99.8%, which can be directly sold as a by-product; the aqueous phase is water with a low organic content (mainly composed of 99.93wt% water, 0.04wt% acetone, and 0.02wt% isopropanol), which is directly sent to wastewater treatment; the bottom liquid of the light removal tower (mainly composed of 67.84wt% acetone, 8.80wt% water, 21.46wt% MIBK, 0.68wt% isopropanol, 0.36wt% diisobutyl ketone, 0.8wt% mesitylene, 0.02wt% mesityl oxide, and 0.04wt% oligomer) is sent to a deacetone tower;

[0030] (2) The bottom liquid of the light-removing tower is sent to the deacetone tower for rectification. The deacetone tower is operated at negative pressure, with a top pressure of -25.5 KPaG, a top temperature of 47.9°C, a bottom pressure of -1.5 KPaG, and a bottom temperature of 116.5°C. Acetone with a purity of 99.5% is extracted from the top of the deacetone tower, and the acetone is recycled back to the reaction unit to continue to participate in the reaction. A phase separator is provided in the middle of the stripping section of the deacetone tower to draw out all the liquid phase in the tower and introduce the phase separator for phase separation. After phase separation, the organic phase (mainly composed of MIBK71.01wt%, isopropanol20.51wt%, water6.98wt%, acetone0.65wt%, diisobutyl ketone0.24wt%, mesitylene0.56wt%, mesityl oxide0.02wt%, oligomer0.02wt%) was returned to the tower, and 41.3wt% of the aqueous phase (mainly composed of water90.75wt%, isopropanol7.13wt%, MIBK 1.76wt%, acetone 0.35wt%, mesityl oxide 0.01%) was cooled to 38°C by a cooler and then refluxed to the lightness removal tower as an extractant, and the remaining 58.7wt% of water phase was sent to the dehydration tower; the mass fraction of water in the middle of the stripping section of the deacetone tower was high, so after phase separation, from the perspective of material balance, the water sent to the distillation system can be completely discharged; in addition, since a large amount of water is discharged, the boiling point of water and isopropanol (azeotropic temperature 80°C) and water and MIBK (azeotropic temperature 88°C) can be greatly reduced. Azeotropic reaction makes it possible to separate isopropanol, water and MIBK, which were difficult to separate before, very well. Therefore, the discharge from the acetone removal tower is MIBK and other heavier components (mainly composed of 94.56wt% MIBK, 1.63wt% diisobutyl ketone, 3.55wt% mesitylene, 0.08wt% mesityl oxide and 0.17wt% oligomers), and all isopropanol leaves with the water phase of the phase separator. The acetone removal tower bottom liquid can be directly sent to the MIBK product tower for distillation separation to obtain the MIBK product.

[0031] (3) The bottom liquid of the deacetone tower is sent to the MIBK product tower for rectification. The MIBK product tower is operated at normal pressure, with a top pressure of 2.5 KPaG, a top temperature of 117.1°C, a bottom pressure of 19 KPaG, and a bottom temperature of 171.2°C. The MIBK product tower produces a MIBK product with a purity of 99.5% at the top, and produces heavy components (mainly composed of 63.80 wt% of mesitylene, 32.04 wt% of diisobutyl ketone, 0.50 wt% of MIBK, 0.23 wt% of mesityl oxide, and 3.43 wt% of oligomers) at the bottom. If there is a need, a DIBK tower can be added to recover diisobutyl ketone (DIBK);

[0032] (4) The remaining water phase of the acetone removal tower is sent to a dehydration tower for dehydration. The dehydration tower is operated at normal pressure, with a tower top pressure of 3.5 KPaG, a tower top temperature of 80.4° C., a tower bottom pressure of 7.5 KPaG, and a tower bottom temperature of 101.8° C.; the tower top of the dehydration tower is an organic light component mixture (mainly composed of 63.48 wt% of isopropanol, 17.74 wt% of water, 15.63 wt% of MIBK, 3.10 wt% of acetone, and 0.04 wt% of mesityl oxide), and the tower bottom is water with a low organic matter content (mainly composed of 99.992 wt% of water), which is sent to wastewater treatment.

[0033] Example 2

[0034] An energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step, such as Figure 3 As shown, the following steps are included:

[0035] (1) The crude product (composition: acetone 70.60 wt%, MIBK 22.32wt%, water 5.38wt%, 2-methylpentane 0.34wt%, isopropanol 0.42wt%, diisobutyl ketone 0.40wt%, mesitylene 0.50wt%, mesitylene oxide 0.01wt%, oligomer 0.03wt%) first enters a lightness removal tower, which is an extractive distillation tower. The extractant is water, and the extractant comes from the aqueous phase of the phase separator of the acetone removal tower. The lightness removal tower is operated at normal pressure, with a tower top pressure of 5KPaG, a tower top temperature of 39.3°C, a tower bottom pressure of 28.9KPaG, and a tower bottom temperature of 68.8°C. The extractive distillation solves the azeotropic problem of 2-methylpentane and acetone, and acetone no longer leaves the tower top with 2-methylpentane. At this time, the top of the lightness removal tower is produced as an azeotropic mixture of 2-methylpentane and water (mainly composed of 96 .66wt%, water 3.20wt%, isopropanol 0.12wt%, MIBK0.02wt%), and the top material is subsequently sent to a phase separator; since water and 2-methylpentane are completely immiscible, the organic phase after phase separation is 2-methylpentane with a purity of 99.8%, which can be directly sold as a by-product; the aqueous phase is water with a low organic content (mainly composed of water 99.95wt% and isopropanol 0.04wt%), which is directly sent to wastewater treatment; the bottom liquid of the light removal tower (mainly composed of acetone 68.11wt%, water 8.70wt%, MIBK21.60wt%, isopropanol 0.68wt%, diisobutyl ketone 0.39wt%, mesitylene 0.48wt%, mesityl oxide 0.01wt%, and oligomer 0.03wt%) is sent to a deacetone tower;

[0036] (2) The bottom liquid of the light-removing tower is sent to the deacetone tower for rectification. The deacetone tower is operated at negative pressure, with a top pressure of -30.5 KPaG, a top temperature of 46.1°C, a bottom pressure of -6.5 KPaG, and a bottom temperature of 114.4°C. Acetone with a purity of 99.5% is extracted from the top of the deacetone tower, and the acetone is recycled back to the reaction unit to continue to participate in the reaction. A phase separator is provided in the middle of the stripping section of the deacetone tower to draw out all the liquid phase in the tower and introduce the phase separator for phase separation. After phase separation, the organic phase (mainly composed of MIBK72.33wt%, isopropanol20.24wt%, water6.74wt%, acetone0.07wt%, diisobutyl ketone0.25wt%, mesitylene0.34wt%, mesityl oxide0.01wt%, oligomer0.02wt%) was returned to the tower, and 41.9wt% of the aqueous phase (mainly composed of water91.17wt%, isopropanol7.05wt%, MIBK 1.74wt%, acetone 0.04wt%) is cooled to 39°C by a cooler and then refluxed to the light-removing tower as an extractant, and the remaining 58.1wt% of the water phase is sent to the dehydration tower; the mass fraction of water in the middle position of the stripping section of the deacetone tower is relatively high, so after phase separation, from the perspective of material balance, the water sent to the distillation system can be completely discharged; in addition, since a large amount of water is discharged, the azeotropic reaction of water and isopropanol (azeotropic temperature 80°C) and water and MIBK (azeotropic temperature 88°C) can be greatly reduced, so that the isopropanol, water and MIBK that were originally difficult to separate can now be well separated; therefore, the deacetone tower kettle discharge is MIBK and the remaining heavier components (mainly composed of MIBK 95.94wt%, diisobutyl ketone 1.73wt%, mesitylene 2.16wt%, mesitylene oxide 0.04wt%, oligomer 0.13wt%), and all isopropanol leaves with the water phase of the phase separator; the bottom liquid of the deacetone tower can be directly sent to the MIBK product tower for distillation and separation to obtain the MIBK product;

[0037] (3) The bottom liquid of the deacetone tower is sent to the MIBK product tower for rectification. The MIBK product tower is operated at normal pressure, with a top pressure of 6.2 KPaG, a top temperature of 118.4°C, a bottom pressure of 23.7 KPaG, and a bottom temperature of 173.2°C. The MIBK product with a purity of 99.5% is produced from the top of the MIBK product tower, and heavy components (mainly composed of 50.78 wt% of mesitylene, 44.98 wt% of diisobutyl ketone, 0.50 wt% of MIBK, 0.12 wt% of isopropyl acetate, and 3.60 wt% of oligomers) are produced from the bottom of the tower. If there is a demand, a DIBK tower can be added to recover diisobutyl ketone DIBK;

[0038] (4) The remaining water phase of the acetone removal tower is sent to a dehydration tower for dehydration. The dehydration tower is operated at normal pressure, with a tower top pressure of 7.1 KPaG, a tower top temperature of 81.9° C., a tower bottom pressure of 11.9 KPaG, and a tower bottom temperature of 103.0° C. The top of the dehydration tower is an organic light component mixture (mainly composed of 64.67 wt% of isopropanol, 18.99 wt% of water, 15.98 wt% of MIBK, 0.34 wt% of acetone, and 0.02 wt% of mesityl oxide), and the bottom is water with a low organic matter content (mainly composed of 99.995 wt% of water), which is sent to wastewater treatment.

[0039] Example 3

[0040] An energy-saving distillation process for synthesizing methyl isobutyl ketone from acetone in one step, such as Figure 3 As shown, the following steps are included:

[0041] (1) The crude product from the one-step acetone reaction unit using a Pd-supported cation exchange resin as a catalyst (composition: 69.98 wt% acetone, 22.75 wt% MIBK, 5.32 wt% water, 0.32 wt% 2-methylpentane, 0.46 wt% isopropanol, 0.45 wt% diisobutyl ketone, 0.65 wt% mesitylene, 0.01 wt% mesityl oxide, 0.06 wt% oligomer) first enters a lightness removal column, which is an extractive distillation column. The extractant is water, which is derived from the aqueous phase of the phase separator of the acetone removal column. The lightness removal column is operated at normal pressure, and the top pressure is 6.8 K. The extractive distillation solves the azeotropic problem of 2-methylpentane and acetone. Acetone no longer leaves the top of the light-removing tower with 2-methylpentane. At this time, the top of the light-removing tower produces an azeotropic mixture of 2-methylpentane and water (mainly composed of 96.80wt% 2-methylpentane, 3.05wt% water, 0.13wt% isopropanol, and MIBK 0.02wt%), and the top material is subsequently sent to a phase separator; since water and 2-methylpentane are completely immiscible, the organic phase after phase separation is 2-methylpentane with a purity of 99.8%, which can be directly sold as a by-product; the aqueous phase is water with a low organic content (mainly composed of 99.95wt% water and 0.04wt% isopropanol), which is directly sent to wastewater treatment; the bottom liquid of the light removal tower (mainly composed of 67.50wt% acetone, 8.61wt% water, 22.01wt% MIBK, 0.74wt% isopropanol, 0.43wt% diisobutyl ketone, 0.63wt% mesitylene, 0.01wt% mesityl oxide, and 0.06wt% oligomer) is sent to a deacetone tower;

[0042] (2) The bottom liquid of the light-removing tower is sent to the deacetone tower for rectification. The deacetone tower is operated at negative pressure, with a top pressure of -32.5 KPaG, a top temperature of 45.3°C, a bottom pressure of -8.5 KPaG, and a bottom temperature of 113.8°C. Acetone with a purity of 99.5% is extracted from the top of the deacetone tower, and the acetone is recycled back to the reaction unit to continue to participate in the reaction. A phase separator is provided in the middle of the stripping section of the deacetone tower to draw out all the liquid phase in the tower and introduce the phase separator for phase separation. After phase separation, the organic phase (mainly composed of MIBK 69.66wt%, isopropanol 22.44wt%, water 7.07wt%, acetone 0.05wt%, diisobutyl ketone 0.28wt%, mesitylene 0.45wt%, mesityl oxide 0.01wt%, oligomer 0.04wt%) was returned to the tower, and 42.0wt% of the aqueous phase (mainly composed of water 90.46wt%, isopropanol 7.75wt%, MIBK 1.76wt%, acetone 0.03wt%) is cooled to 39°C by a cooler and then refluxed to the light-removing tower as an extractant, and the remaining 58.0wt% of the water phase is sent to the dehydration tower; the mass fraction of water in the middle position of the stripping section of the deacetone tower is relatively high, so after phase separation, from the perspective of material balance, the water sent to the distillation system can be completely discharged; in addition, since a large amount of water is discharged, the azeotropy of water and isopropanol (azeotropic temperature 80°C) and water and MIBK (azeotropic temperature 88°C) can be greatly reduced, so that the isopropanol, water and MIBK that were originally difficult to separate can now be well separated; therefore, the deacetone tower kettle discharge is MIBK and the remaining heavier components (mainly composed of MIBK 95.09wt%, diisobutyl ketone 1.89wt%, mesitylene 2.72wt%, mesitylene oxide 0.04wt%, oligomer 0.25wt%), and all isopropanol leaves with the water phase of the phase separator; the bottom liquid of the deacetone tower can be directly sent to the MIBK product tower for distillation and separation to obtain the MIBK product;

[0043] (3) The bottom liquid of the deacetone tower is sent to the MIBK product tower for rectification. The MIBK product tower is operated at normal pressure, with a top pressure of 8.2 KPaG, a top temperature of 119.0°C, a bottom pressure of 25.7 KPaG, and a bottom temperature of 174.1°C. A MIBK product with a purity of 99.5% is produced from the top of the MIBK product tower, and heavy components (mainly composed of 53.12 wt% of mesitylene, 40.62 wt% of diisobutyl ketone, 0.50 wt% of MIBK, 0.11 wt% of isopropyl acetate, and 5.65 wt% of oligomers) are produced from the bottom of the tower. If there is a need, a DIBK tower can be added to recover diisobutyl ketone (DIBK);

[0044] (4) The remaining water phase of the acetone removal tower is sent to a dehydration tower for dehydration. The dehydration tower is operated at normal pressure, with a tower top pressure of 8.6 KPaG, a tower top temperature of 82.2° C., a tower bottom pressure of 13.4 KPaG, and a tower bottom temperature of 103.3° C. The top of the dehydration tower is an organic light component mixture (mainly composed of 66.37 wt% of isopropanol, 18.37 wt% of water, 15.02 wt% of MIBK, 0.22 wt% of acetone, and 0.02 wt% of mesityl oxide), and the bottom is water with a low organic matter content (mainly composed of 99.996 wt% of water), which is sent to wastewater treatment.

[0045] The above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by a person skilled in the art within the spirit and scope of the present invention shall also fall within the protection scope of the present invention.

Claims

1. A distillation process for synthesizing methyl isobutyl ketone from acetone in one step, characterized in that: The steps include: (1) The crude product from the acetone one-step reaction unit first enters a light-removal tower, which is an extractive distillation tower. The extractant is water, which comes from the aqueous phase of the phase separator of the acetone removal tower. The overhead product of the light-removal tower is an azeotrope of 2-methylpentane and water, and the overhead material is subsequently sent to the phase separator. The organic phase after phase separation is high-purity 2-methylpentane, and the aqueous phase is water with a low organic content. (2) the bottom liquid of the lightness removal tower is sent to the acetone removal tower for rectification, and high-purity acetone is extracted from the top of the acetone removal tower, and the acetone is circulated back to the reaction unit to continue to participate in the reaction; a phase separator is provided in the middle position of the stripping section of the acetone removal tower, and all the liquid phase in the tower is drawn out and introduced into the phase separator for phase separation. After the phase separation, the organic phase is returned to the tower, and part of the water phase is cooled by the cooler and refluxed to the lightness removal tower as an extractant, and the remaining water phase is sent to the dehydration tower; The output from the acetone removal tower is MIBK and other heavier components, while all isopropanol leaves with the water phase of the phase separator. (3) The bottom liquid of the acetone removal tower is sent to the MIBK product tower for rectification, and a high-purity MIBK product is produced from the top of the MIBK product tower, and heavy components are produced from the bottom of the tower; (4) Part of the water phase of the acetone removal tower is sent to a dehydration tower for dehydration. The top of the dehydration tower is a mixture of organic light components, and the bottom of the tower is water with a low organic content; In the step (1), the acetone one-step method uses a Pd-loaded cation exchange resin as a catalyst.

2. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step as claimed in claim 1, characterized in that: In the step (1), the crude reaction product includes acetone, MIBK, water, 2-methylpentane, isopropanol, diisobutyl ketone, mesitylene, mesitylene oxide, and oligomers.

3. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step as claimed in claim 2, characterized in that: Measured by mass percentage, the crude reaction product includes 69.98% to 70.60% of acetone, 22.18% to 22.75% of MIBK, 5.32% to 5.50% of water, 0.31% to 0.34% of 2-methylpentane, 0.42% to 0.46% of isopropanol, 0.38% to 0.45% of diisobutyl ketone, 0.50% to 0.83% of mesitylene, 0.01% to 0.02% of mesityl oxide, and 0.03% to 0.06% of oligomers.

4. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step according to claim 1, characterized in that: In the step (1), the light-removal tower is operated at normal pressure, the tower top pressure is 0-10 KPaG, the tower top temperature is 37-42°C, the tower bottom pressure is 23-35 KPaG, and the tower bottom temperature is 65-72°C.

5. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step according to claim 1, characterized in that: In the step (2), the deacetone tower is operated under negative pressure, the tower top pressure is -35 to -25 KPaG, the tower top temperature is 44 to 50°C, the tower bottom pressure is -10 to 0 KPaG, and the tower bottom temperature is 112 to 118°C.

6. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step according to claim 1, characterized in that: In the step (2), 41.0 wt% to 42.0 wt% of the aqueous phase is cooled in a cooler and then refluxed to the lightness removal tower as an extractant, and the remaining aqueous phase is sent to a dehydration tower.

7. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step according to claim 1, characterized in that: In the step (3), the MIBK product tower is operated at normal pressure, the tower top pressure is 0-10 KPaG, the tower top temperature is 115-120°C, the tower bottom pressure is 15-29 KPaG, and the tower bottom temperature is 168-178°C.

8. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step according to claim 1, characterized in that: In the step (3), the bottom liquid of the MIBK product tower is sent to a DIBK tower to recover diisobutyl ketone (DIBK).

9. The distillation process for synthesizing methyl isobutyl ketone from acetone in one step according to claim 1, characterized in that: In the step (4), the dehydration tower is operated at normal pressure, the top pressure is 0-10 KPaG, the top temperature is 75-85°C, the bottom pressure is 3-15 KPaG, and the bottom temperature is 100-105°C.

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