Method and device for recovering solvent in production of MIBK (methyl isobutyl ketone) from acetone

Abstract

The invention relates to a method and a device for recovering a solvent in production of MIBK (Methyl Isobutyl Ketone) from acetone, belonging to the technical field of separation. Comprising the following steps: feeding a material containing acetone, isopropanol, MIBK and water into an acetone-removing rectifying tower for separation, and distilling out acetone from the tower top; feeding a tower kettle material of the acetone rectifying tower into a dehydration rectifying tower for separation, and distilling out water from the tower top; feeding MIBK and isopropanol gas phase into a membrane at the top of the tower, removing the membrane and dehydrating; the separation of isopropyl alcohol and MIBK is carried out on an interception side material MIBK separation rectifying tower of the dehydration separation membrane, MIBK is obtained from a tower kettle, and isopropyl alcohol is obtained from a side line at a feeding position. The separation of acetone, isopropanol, MIBK and water can be realized, and the recovered solvent is obtained.

Description

Technical Field

[0001] The invention relates to a method and a device for recovering a solvent in producing MIBK from acetone, belonging to the technical field of separation. Background Art

[0002] Methyl isobutyl ketone (MIBK) is an important chemical raw material, widely used in fine chemical products, rubber antioxidants, surfactants, pharmaceutical intermediates and other fields. The acetone one-step method is one of the main industrial methods for producing MIBK. Its basic principle involves acetone and isopropanol undergoing condensation, dehydration and hydrogenation steps under the action of a catalyst to produce MIBK. In this process, the conversion rate of acetone is about 30% and the selectivity of MIBK is about 94%. However, in addition to the target product MIBK, the process also produces a variety of by-products, including water, isopropanol and diisobutyl ketone (DIBK). The presence of these by-products makes the separation of the reaction products complicated.

[0003] Since acetone, isopropanol, MIBK and water have similar boiling points, they tend to form azeotropes, which increases the difficulty of separation. Traditional distillation technology is difficult to effectively separate these components because they form constant boiling mixtures under normal conditions. Therefore, special separation technology is required to achieve effective separation of these components. Summary of the invention

[0004] The invention provides a solvent recovery method applied to the production of MIBK from acetone, which can separate acetone, isopropanol, MIBK and water to obtain a recovered solvent.

[0005] The technical solution is:

[0006] A method for recovering solvent in the production of MIBK from acetone comprises the following steps:

[0007] The material containing acetone, isopropanol, MIBK and water is sent to a deacetone distillation tower for separation, and acetone is distilled out from the top of the tower;

[0008] The bottom material of the acetone distillation tower is sent to the dehydration distillation tower for separation;

[0009] The top material of the dehydration distillation tower is dehydrated through a dehydration separation membrane;

[0010] The interception side material of the dehydration separation membrane is separated into a MIBK separation distillation tower for isopropanol and MIBK, and MIBK is obtained in the tower bottom, and isopropanol is obtained by discharging a side line above the tower feed position.

[0011] The material containing acetone, isopropanol, MIBK and water comprises: 6-8% acetone, 50-55% isopropanol, 18-22% MIBK methyl isobutyl ketone, 15-25% water, and the rest are impurities.

[0012] In the deacetone distillation tower, the operating pressure is atmospheric pressure, the tower bottom temperature range is 50-62°C, and the tower top temperature range is 80-95°C.

[0013] The number of plates of the deacetone distillation tower is 20-45, the feed position is 15-22, and the reflux ratio is 15-25; and water extractant is added at the position of the 5th to 15th plate.

[0014] The bottom temperature of the dehydration distillation tower is 130-140°C, the top temperature is 105-120°C, the pressure is 150-200kPa, and the reflux ratio is 0.8-1.4.

[0015] The dehydration distillation tower has 12-25 plates and 7-13 feed positions.

[0016] The materials of the dehydration separation membrane are NaA molecular sieve, polyvinyl alcohol, ZSM-5 zeolite membrane, MOR molecular sieve, and NaY molecular sieve.

[0017] The pressure range of the permeate side of the dehydration separation membrane is 500-4000Pa absolute pressure, and the feed temperature range is 70-120°C.

[0018] The number of plates of the MIBK separation distillation tower is 15-40; the feed position is 10-28 plates, the top temperature of the MIBK separation distillation tower is 70-85°C, and the bottom temperature is 110-130°C.

[0019] The solvent recovery device in the production of MIBK from acetone includes:

[0020] The acetone removal distillation tower is used to distill and separate materials containing acetone, isopropanol, MIBK and water, so that acetone is distilled from the top of the tower;

[0021] A dehydration distillation tower is connected to the bottom of the deacetone distillation tower and is used to distill and separate the materials in the bottom of the tower so that water can be discharged from the bottom of the tower;

[0022] A dehydration separation membrane is connected to the bottom of the dehydration distillation tower and is used to perform membrane dehydration on the bottom material;

[0023] The MIBK separation distillation tower is connected to the interception side of the dehydration separation membrane and is used to separate MIBK and isopropanol from the intercepted material, and MIBK is obtained in the tower bottom.

[0024] The number of plates of the deacetone distillation tower is 20-45, and the feed position is 15-22.

[0025] An extractant inlet is provided at the top of the deacetone distillation tower for supplying water extractant. The extractant inlet is located at the 5th to 15th tower plates.

[0026] The dehydration separation membrane is made of NaA molecular sieve, polyvinyl alcohol, ZSM-5 zeolite membrane, MOR molecular sieve and NaY molecular sieve.

[0027] The number of plates of the dehydration distillation tower is 15-40; the number of plates at the feed position is 10-28.

[0028] The number of plates of the MIBK separation distillation tower is 15-30.

[0029] The tower bottom of the dehydration separation membrane is connected to the extractant addition port, and the obtained water is reused as the extractant.

[0030] The invention also comprises a reboiler for heating the material entering the dehydration separation membrane.

[0031] It also includes a negative pressure device connected to the permeate side of the dehydration separation membrane and used for making the permeate side have negative pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the flow chart of this patent.

[0033] Figure 2 It is the device diagram of this patent. DETAILED DESCRIPTION

[0034] The solvent material processed in this patent is obtained from the production of MIBK from acetone, and its main components are: synthetic liquid components: acetone 6-8%, isopropanol 50-55%, MIBK methyl isobutyl ketone 18-22%, water 15-25%, and the rest are impurities. In the following examples, the material components (mass percentage) include: acetone 7.01%, isopropanol 52.96%, MIBK methyl isobutyl ketone 19.88%, water 20%, and the rest are impurities.

[0035] The core of the device of this patent is four processing units, which are equipped with four solvent recovery systems, namely, the deacetone distillation recovery system, the pre-membrane dehydration tower system, the membrane dehydration system, and the post-membrane isopropanol and MIBK recovery system.

[0036] The main process steps are:

[0037] 1) The mother liquor is pumped to the lower middle part of the deacetone tower, and acetone is distilled from the top; an appropriate amount of extraction water is introduced into the upper part of the tower to prevent isopropanol from being carried to the top of the tower by water, and acetone is distilled out of the tower bottom as much as possible.

[0038] 2) The bottom material of the acetone removal tower is sent to the isopropanol and MIBK membrane coupling tower for dehydration. The gas phase at the top of the tower enters the membrane device to remove moisture, and the anhydrous isopropanol and MIBK gas phases are further separated in the post-membrane tower.

[0039] 3) Isopropyl alcohol product is produced from the side line of the tower after the membrane, MIBK product is produced from the bottom of the tower, and the water, acetone and isopropyl alcohol enriched at the top of the tower are refluxed into the feed buffer tank for re-separation.

[0040] 1. Acetone removal distillation recovery system

[0041] The mother liquor from the tank area is transported by the mother liquor transfer pump, passes through the preheater, and after heat exchange with the bottom liquid of the pre-membrane tower, enters the middle and lower part of the deacetone tower. After heat exchange, part of the bottom liquid of the pre-membrane tower returns to the extraction water tank, and part goes to the bottom liquid cooler of the pre-membrane tower. The bottom liquid entering the extraction water tank is input into the middle part of the tower by the extraction water pump as the extractant of the deacetone tower. Fresh process water is input into the middle and upper part of the deacetone tower by the process water pump. The heat source of the tower bottom consists of two parts. The main reboiler is provided by 0.4MPa, 153℃ saturated water vapor, and the waste heat reboiler is provided by the top steam of the pre-membrane tower. The deacetone tower is operated continuously at normal pressure, and the operating temperature is 58~90℃.

[0042] After the deacetone tower is operated stably with full reflux, acetone / a small amount of isopropanol vapor at about 58°C is extracted from the top of the tower, and condensed by 32-42°C circulating cooling water in the first condenser at the top of the tower, and condensed by 7-17°C low-temperature water in the second condenser at the top of the tower. After the top gas is condensed, it enters the reflux tank, and the reflux liquid is partially returned to the tower through the reflux pump. Part of the acetone product is cooled to about 45°C by the top cooler and then sent to the designated location. The bottom liquid is isopropanol and MIBK aqueous solution, which is input into the middle of the pre-membrane dehydration tower through the bottom pump.

[0043] 2. Pre-membrane dehydration tower distillation recovery system

[0044] The isopropanol / MIBK / water solution from the deacetone tower is pumped into the middle of the pre-membrane dehydration tower by the tower bottom pump. The tower is pressurized and operated continuously, with an operating pressure of 0.2-0.35 MPaG and an operating temperature of 112-135°C. The heat source of the tower bottom is provided by saturated water vapor at 0.5 MPa and 159°C.

[0045] After the pre-membrane dehydration tower is fully refluxed and operated stably, isopropanol / MIBK / water vapor at about 112°C is extracted from the top of the tower, which is partially condensed by 32-42°C circulating cooling water in the top condenser. Part of the top gas enters the membrane system for further treatment, and part of it enters the reflux tank after condensation and is transported back to the top of the tower by the reflux pump. The bottom liquid is a mixture of heavy components and water, which is transported to the preheater of the deacetone tower by the bottom pump. After heat exchange with the raw materials, part of it goes to the extraction water tank, and part of it goes back to the bottom cooler, cooled to about 45°C, and then goes to the designated location.

[0046] 3. Membrane dehydration system

[0047] The isopropanol / MIBK vapor phase steam with a water content of ≤20wt.% that meets the membrane entry requirements is superheated by the heater E7301 and enters the membrane separation unit M7301-M7312 in the form of superheated steam. The operating pressure of the whole set of equipment is about 0.2-0.35MPa(G). The membrane separation unit is composed of 12 membrane modules in series. The water in the raw material and a small amount of isopropanol / MIBK permeate from the upstream side to the downstream side through the membrane module. The product on the upstream side of the membrane is the isopropanol / MIBK finished product steam with a water content of less than 0.06wt.%, which is removed from the membrane and then treated in the tower;

[0048] The downstream side of the membrane adopts the method of vacuum extraction and condensation to form a vapor partial pressure difference between the components on the upstream and downstream sides of the membrane. The pressure on the permeate side is 4 / 1.2 / 0.8 KPa. The permeate vapor on the downstream side of the membrane enters the permeate condenser under the suction of the vacuum machine. The condensed permeate accumulates in the permeate tank. When the permeate tank is at a high level, an alarm is issued, and the negative pressure pump is automatically started for full reflux. After 30 seconds, the pneumatic ball valve at the pump outlet is started to discharge the permeate. When the permeate tank is at a low level, an alarm is issued, the pneumatic ball valve is automatically closed, and the negative pressure pump is automatically stopped after 30 seconds. The permeate is transported to the extraction water tank for use via the negative pressure pump.

[0049] 4. Post-membrane isopropanol and MIBK recovery system

[0050] The steam from the finished membrane product enters the middle of the tower after the membrane in the form of gas phase. The tower is operated continuously at normal pressure and the operating temperature is 82-121°C. The heat source of the tower kettle is provided by 0.5MPa, 159°C saturated water vapor.

[0051] After the post-membrane product tower is operated stably with full reflux, isopropanol / acetone vapor at about 82°C is extracted from the top of the tower. After passing through the first-level condenser and the second-level condenser at the top of the tower, it flows by gravity to the reflux tank, part of which returns to the tower, and part of which is extracted to the feed buffer tank to continue to recover the isopropanol. The isopropanol product is extracted from the upper side of the tower, cooled to about 45°C by the intermediate cooler, and flows by gravity to the isopropanol buffer tank, which is transported by the isopropanol transfer pump. The isopropanol that meets the recycling requirements goes to the designated location, and the isopropanol that does not meet the recycling requirements returns to the feed buffer tank to continue to recover the isopropanol. The tower bottom is the MIBK product that meets the recycling requirements, which is transported by the tower bottom pump, cooled to 45°C by the tower bottom cooler, and sent to the designated location.

[0052] After the separation process of this patent, the following purities of solvents and materials can be obtained:

[0053] Required Products Quality control requirements wt.% acetone Purity ≥99% (excluding water), water ≤5% Isopropyl alcohol Purity ≥99.9% (excluding water), water ≤0.1% MIBK Isopropyl alcohol wt.% ≤ 2%, water ≤ 4%

[0054] Example 1

[0055] The mixed material containing acetone, isopropanol, MIBK and water is first sent to a deacetone tower for distillation and deacetone treatment, the tower bottom temperature is maintained at 55-58°C, the tower top temperature is maintained at 88-90°C, the pressure is normal pressure, the number of tower plates is 33, the feed position is at the 17th tower plate, after the total reflux operation is stable, the reflux ratio is set to 18, and at the same time, part of water is added to the upper part of the tower as an extractant, and acetone is evaporated from the top of the tower; the bottom liquid is mainly composed of: water 28.1%, isopropanol 51.6%, MIBK 19.1%, acetone 0.8%; the purity of the top acetone is 99.1%;

[0056] The bottom liquid mainly contains an aqueous solution of isopropanol, MIBK and acetone, which is then sent to a dehydration tower for preliminary dehydration. The feed position is in the middle of the tower, the number of plates is 20, the bottom temperature is 132°C, the top temperature is 110°C, the pressure is 200kPaG, the reflux ratio is 1, and the gas phase composition at the top of the tower is 68.2% isopropanol, 28.5% MIBK, 3.2% water, and 0.4% acetone;

[0057] The top gas phase is sent to the NaA molecular sieve membrane for dehydration. The feed temperature is 92-95°C, the absolute pressure on the permeate side is 800 Pa, and the permeate side contains 95.7% water. The water content on the interception side drops to 0.02%. It contains 73.02% isopropanol, 26.77% MIBK, and 0.2% acetone.

[0058] The dehydrated material on the interception side is sent to the MIBK separation tower for distillation separation with isopropanol. The number of tower plates is 32, the tower top temperature is 73°C, the feed position is the 22nd tower plate, the tower bottom temperature is 118°C, isopropanol is produced on the 3rd tower plate, and MIBK is produced from the tower bottom; the purity of the product isopropanol reaches 99.3%, and the purity of MIBK is 99.2%.

[0059] Example 2

[0060] The mixed material containing acetone, isopropanol, MIBK and water is first sent to a deacetone tower for distillation and deacetone treatment, the tower bottom temperature is maintained at 58-60°C, the tower top temperature is maintained at 90-92°C, the pressure is normal pressure, the number of tower plates is 34, the feed position is at the 18th tower plate, after the total reflux operation is stable, the reflux ratio is set to 20, and at the same time, part of water is added to the upper part of the tower as an extractant, and acetone is evaporated from the top of the tower; the bottom liquid is mainly composed of: water 28.6%, isopropanol 51.4, MIBK 19.7%, acetone 0.7%; the purity of the acetone at the top of the tower is 99.2%;

[0061] The bottom liquid mainly contains isopropanol and MIBK aqueous solution, which is then sent to the dehydration tower for preliminary dehydration. The feed position is in the middle of the tower, the number of plates is 22, the bottom temperature is 130°C, the top temperature is 108°C, the pressure is 200kPaG, the reflux ratio is 1, and the top gas phase is 68.4% isopropanol, 28.7% MIBK, 2.8% water, and 0.3% acetone;

[0062] The gas phase at the top of the tower is sent to the NaA molecular sieve membrane for dehydration. The feed temperature is 92-95°C, the absolute pressure on the permeate side is 1400 Pa, and the permeate side contains 95.1% water, while the water content on the interception side drops to 0.02%, isopropanol 73.25%, MIBK 26.63%, and acetone 0.2%.

[0063] The dehydrated material on the interception side is sent to the MIBK separation tower for distillation separation with isopropanol. The number of tower plates is 30, the tower top temperature is 71°C, the feed position is the 20th tower plate, the tower bottom temperature is 120°C, isopropanol is produced on the 3rd tower plate, and MIBK is produced from the tower bottom; the purity of the product isopropanol reaches 99.4%, and the purity of MIBK is 99.3%.

Claims

1. A method for recovering solvent in the production of MIBK from acetone, characterized in that: The steps include: The material containing acetone, isopropanol, MIBK and water is sent to a deacetone distillation tower for separation, and acetone is distilled out from the top of the tower; The bottom material of the acetone distillation tower is sent to the dehydration distillation tower for separation; The top material of the dehydration distillation tower is dehydrated through a dehydration separation membrane; The interception side material of the dehydration separation membrane is separated into a MIBK separation distillation tower for isopropanol and MIBK, and MIBK is obtained in the tower bottom, and isopropanol is obtained by discharging a side line above the tower feed position.

2. The method for recovering solvent from MIBK produced by acetone according to claim 1, wherein: The material containing acetone, isopropanol, MIBK and water comprises: 6-8% acetone, 50-55% isopropanol, 18-22% MIBK methyl isobutyl ketone, 15-25% water, and the rest are impurities.

3. The method for recovering solvent in the production of MIBK by acetone according to claim 1, characterized in that: In the deacetone distillation tower, the operating pressure is atmospheric pressure, the tower bottom temperature range is 50-62°C, and the tower top temperature range is 80-95°C.

4. The method for recovering solvent in the production of MIBK by acetone according to claim 1, characterized in that: The number of plates of the deacetone distillation tower is 20-45, the feed position is 15-22, and the reflux ratio is 15-25; and water extractant is added at the position of the 5th to 15th plate.

5. The method for recovering solvent in the production of MIBK from acetone according to claim 1, characterized in that: The bottom temperature of the dehydration distillation tower is 130-140°C, the top temperature is 105-120°C, the pressure is 150-200kPa, and the reflux ratio is 0.8-1.

4.

6. The method for recovering solvent in the production of MIBK from acetone according to claim 1, characterized in that: The dehydration distillation tower has 12-25 plates and 7-13 feed positions.

7. The method for recovering solvent in the production of MIBK from acetone according to claim 1, characterized in that: The materials of the dehydration separation membrane are NaA molecular sieve, polyvinyl alcohol, ZSM-5 zeolite membrane, MOR molecular sieve, and NaY molecular sieve.

8. The method for recovering solvent in the production of MIBK from acetone according to claim 1, characterized in that: The pressure range of the permeate side of the dehydration separation membrane is 500-4000Pa absolute pressure, and the feed temperature range is 70-120°C.

9. The method for recovering solvent in the production of MIBK from acetone according to claim 1, characterized in that: The number of plates of the MIBK separation distillation tower is 15-40; the feed position is 10-28 plates, the top temperature of the MIBK separation distillation tower is 70-85°C, and the bottom temperature is 110-130°C.

10. A solvent recovery device for producing MIBK from acetone, characterized in that: include: The acetone removal distillation tower is used to distill and separate materials containing acetone, isopropanol, MIBK and water, so that acetone is distilled out from the top of the tower; an extractant addition port is provided at the top of the acetone removal distillation tower for supplying water extractant; A dehydration distillation tower is connected to the bottom of the deacetone distillation tower and is used to distill and separate the materials in the bottom of the tower so that water can be discharged from the bottom of the tower; A dehydration separation membrane is connected to the top of the dehydration distillation tower and is used to perform membrane dehydration on the materials in the bottom of the tower; The MIBK separation distillation tower is connected to the interception side of the dehydration separation membrane and is used to separate MIBK and isopropanol from the intercepted material, and MIBK is obtained in the tower bottom.

Images