Device and method for preparing methyl isoamyl ketone

Abstract

The present application provides a device and method for preparing methyl isoamyl ketone. In the method, acetone and isobutyraldehyde are reacted under the catalysis of a condensation catalyst and a hydrogenation catalyst in the presence of hydrogen to obtain the methyl isoamyl ketone, wherein the condensation catalyst comprises an organic base; and the molar ratio of the condensation catalyst to the isobutyraldehyde is (0.02-0.15):1. The MIAK obtained by the method has at least one of the advantages of high conversion rate, simple process flow, low production cost, easy separation of side reaction products, and high product purity.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and particularly relates to a device and a method for preparing methyl isoamyl ketone. Background Art

[0002] Methyl Isoamyl Ketone (MIAK), chemical name is 5-methyl-2-hexanone, is a colorless transparent liquid with light fragrance. It is mainly used as a solvent for cellulose acetate, acrylic resin, polyvinyl alcohol formal resin, etc. MIAK is also the main raw material for preparing p-phenylenediamine rubber antioxidants 7PPD, 77PD, TMPPD. At present, the main industrial method for synthesizing methyl isoamyl ketone at home and abroad is the isobutyraldehyde-acetone method, which can be synthesized by a two-step method or a one-step method of condensation hydrogenation.

[0003] The one-step condensation hydrogenation method for synthesizing methyl isoamyl ketone is to firstly subject the two raw materials to aldol condensation, and then to form the target product through dehydration and hydrogenation. Specifically, isobutyraldehyde and acetone undergo aldol condensation reaction under the catalysis of alkali or acid to form 4-hydroxy-5-methyl-2-hexanone, which is then dehydrated to form two isomers of 5-methyl-3-hexen-2-one and 5-methyl-4-hexen-2-one, and then both are hydrogenated to obtain the target product 5-methyl-2-hexanone. The reaction formula is as follows:

[0004]

[0005] However, since both raw materials contain α-H atoms, self-condensation and cross-condensation may occur during the condensation process. Multiple condensation reactions occur in the system, resulting in more side reactions, reduced selectivity of the target product, and complex post-processing.

[0006] Although the selectivity of the condensation process can be improved by selecting an alkaline condensation catalyst in the related art, what is mostly used is a water-soluble inorganic base, such as alkali metals or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, and sodium carbonate. On the one hand, the selectivity of the above-mentioned condensation catalyst to the condensation reaction is still limited, and on the other hand, the solubility in the raw materials (acetone and isobutyraldehyde) is relatively low. In order for the catalyst to fully contact the raw materials, it is necessary to introduce a large amount of aqueous solvents in the reaction system. However, the condensation product generated by the reaction is not soluble in water, so a two-phase system is gradually formed as the reaction proceeds, and precipitation will also occur when the alkali concentration is high. Therefore, it is usually necessary to stir vigorously during the reaction. In addition, the catalyst of strong alkalinity also increases the corrosion to the equipment, and in addition to the conditions such as violent stirring and reaction heating, the corrosion resistance of the production equipment is relatively high, and a large amount of alkaline waste water will also be produced.

[0007] Therefore, the current method and device for preparing methyl isoamyl ketone still need to be improved. Summary of the invention

[0008] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing methyl isoamyl ketone, so as to alleviate or even solve at least one of the above problems to at least a certain extent.

[0009] In order to achieve the above object, the present invention provides a method for preparing methyl isoamyl ketone. In the method, acetone and isobutyraldehyde are reacted under the catalysis of a condensation catalyst and a hydrogenation catalyst in the presence of hydrogen to obtain the methyl isoamyl ketone, the condensation catalyst comprises an organic base, and the molar ratio of the condensation catalyst to the isobutyraldehyde is (0.02-0.15):1.

[0010] The present invention uses an organic base as a catalyst for the aldol condensation reaction, the selectivity of the condensation reaction is stronger, and the condensation reaction of acetone and isobutyraldehyde itself can be more effectively avoided, thereby better improving the selectivity and reaction yield of the reaction. In addition, the condensation catalyst has good solubility in the reactant, so there is no need to introduce a large amount of aqueous solvent during the reaction process. After the reaction is completed, the organic base catalyst can be separated by adding water for extraction and repeatedly used, thereby better reducing the production cost.

[0011] Furthermore, the organic base includes at least one of triethylamine, ethylenediamine, pyridine, piperidine, pyrrolidine, and a quaternary ammonium base.

[0012] Wherein, further, the quaternary ammonium hydroxide comprises at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. Wherein, the quaternary ammonium hydroxide is soluble in water and organic solvents, has phase transfer catalysis, can more effectively inhibit the condensation reaction of acetone and isobutyraldehyde itself, can achieve satisfactory conversion rate and selectivity at a lower reaction temperature, so the reaction conditions are milder and the corrosion to the equipment is low. Specifically, the above-mentioned quaternary ammonium hydroxide has a stronger selectivity for 4-hydroxy-5-methyl-2-hexanone with a strong active methylene group, so that it is deprotonated and converted into a carbon anion, while the selectivity for isobutyraldehyde or acetone with relatively inactive methylene groups is slightly poor, so it is not easy to deprotonate them and convert them into a carbon anion, which can greatly improve the selectivity of the condensation reaction.

[0013] Furthermore, the condensation catalyst comprises an aqueous solution containing 3 to 15 wt % of the organic base.

[0014] Furthermore, the condensation catalyst comprises an aqueous solution containing 3 to 6 wt % of the organic base.

[0015] Furthermore, the condensation catalyst comprises an aqueous solution containing 10 to 15 wt % of the organic base.

[0016] For example, the condensation catalyst includes an aqueous solution containing 3 wt %, 5 wt %, 6 wt %, 10 wt %, 12 wt % or 15 wt % of the organic base.

[0017] When the content of the organic base in the condensation catalyst is within the above range, a better catalytic effect can be achieved, and the organic base can be subsequently recovered and reused by water extraction. Excessive or insufficient amounts of the organic base are not conducive to improving the yield of the target product.

[0018] Furthermore, the molar ratio of acetone to isobutyraldehyde is (1-5): 1. The content of acetone in the molar ratio can be any integer or non-integer from 1 to 5, such as 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0019] Furthermore, the molar ratio of the condensation catalyst to the isobutyraldehyde is (0.02-0.1):1, for example, 0.02:1, 0.025:1, 0.03:1, 0.035:1, 0.04:1 or 0.09:1.

[0020] Furthermore, the hydrogenation catalyst includes a carrier and an active metal supported on the carrier.

[0021] Furthermore, relative to the mass of the carrier, the mass percentage of the active metal is 0.1-5%, preferably 0.3-2%, for example, 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0022] In other words, the loading amount of the hydrogenation catalyst is 0.1 to 5%.

[0023] Preferably, the carrier comprises coconut shell activated carbon.

[0024] Preferably, the particle size of the carrier is 6 to 8 meshes.

[0025] Furthermore, the specific surface area of ​​the hydrogenation catalyst is not less than 1000 m 2 / g, thereby increasing the contact area between the reactants and the catalyst and promoting the catalytic effect.

[0026] Preferably, the active metal includes at least one of platinum, palladium, nickel and copper.

[0027] Among them, further, the particle size of the active metal is 3.5-10nm, preferably 3.5-6nm, and further preferably 3.5-5nm, for example, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10.

[0028] In which, further, the hydrogenation catalyst can be a palladium carbon catalyst; the loading amount of palladium can be 0.3-1.5%.

[0029] The inventors were surprised to find that the reason for the low selectivity of isobutyraldehyde in the related art is that on the one hand, the aforementioned raw materials undergo self-condensation side reactions, and on the other hand, the main product formed after dehydration is also prone to generate by-products due to low selectivity during hydrogenation reduction: the C=C double bond and the C=O double bond are conjugated in the molecular structure of the main product 5-methyl-3-hexene-2-one after dehydration. In a non-conjugated system, the C=C double bond is more susceptible to hydrogenation than the C=O double bond, and the C=C double bond can be obtained after hydrogenation reduction to obtain the MIAK product. However, due to the presence of the conjugated system, the hydrogenation reduction activity of the C=O double bond is improved, and it competes with the C=C double bond for hydrogenation, resulting in low selectivity of the target product. The inventors found that different active metals have different catalytic activation sites during hydrogenation reduction. Among active metals such as Pd, Pt, Ni, and Cu, Pd and Ni have higher selectivity for hydrogenation of the C=C double bond. Furthermore, the inventors have found that Pd metal has a high selectivity for catalyzing the hydrogenation of C=C double bonds, while it exhibits a low catalytic activity for C=O double bonds. Therefore, the palladium-carbon catalyst can better improve the selectivity of isobutyraldehyde to MIAK in the method, thereby improving the selectivity and conversion rate of the raw materials.

[0030] Furthermore, the reaction temperature is 50-150°C, preferably 65-145°C, for example 90°C, 98°C, 100°C, 105°C, 125°C or 145°C.

[0031] Furthermore, the pressure of the hydrogen is 1.0-4.0 MPa, preferably 2.0-3.0 MPa, for example 2.5 MPa.

[0032] Furthermore, the speeds at which the acetone, isobutyraldehyde and condensation catalyst are supplied to the reaction device are independently 0.1 to 3 mL / min.

[0033] Furthermore, the acetone and the isobutyraldehyde are supplied to the reaction device at a rate of 1.5 to 3 mL / min; and the condensation catalyst is supplied to the reaction device at a rate of 0.15 to 0.5 mL / min.

[0034] Furthermore, the reaction device of the reaction is a trickle bed reactor, and the reactants are heated at a liquid space velocity of 0.1 to 5.0 h -1 The tail gas is supplied to the reaction device at a flow rate of 0 to 200 mL / min.

[0035] Furthermore, the reactants are heated at a liquid space velocity of 2 to 4 h -1The tail gas is supplied to the reaction device; the tail gas flow rate is 30 to 150 mL / min.

[0036] Furthermore, the conversion rate of the isobutyraldehyde is not less than 98.8%.

[0037] Furthermore, the residual amount of isobutyraldehyde in the product is ≤1.2%.

[0038] Further, the content of methyl isobutyl ketone in the product is not higher than 1.5%, preferably not higher than 0.6%.

[0039] Further, the selectivity of the isobutyraldehyde to the methyl isoamyl ketone is not less than 82%, further, the selectivity of the isobutyraldehyde to the methyl isoamyl ketone is not less than 91%, and further, the selectivity of the isobutyraldehyde to the methyl isoamyl ketone is not less than 92%.

[0040] In another aspect of the present invention, the present invention provides a device for preparing methyl isoamyl ketone. The device comprises:

[0041] A raw material premixing unit, used to mix the raw materials required for synthesizing methyl isoamyl ketone;

[0042] a fixed bed reaction unit, in fluid communication with the raw material premixing unit;

[0043] Wherein, the fixed bed reaction unit is filled with a hydrogenation catalyst.

[0044] Further, the raw material premixing unit includes a first feed port, a second feed port, a third feed port and a premixed raw material outlet; the fixed bed reaction unit has a premixed raw material inlet, a reducing gas inlet and a methyl isoamyl ketone outlet, and the premixed raw material inlet is connected to the premixed raw material outlet. It should be noted that the specific structure of the raw material premixing unit is not particularly limited, for example, it may include but is not limited to structures such as a raw material storage tank, the first feed port, the second feed port, and the third feed port can be connected to the corresponding raw material storage tank, respectively, in order to feed according to a preset ratio, the corresponding raw material storage tank and the first feed port, the second feed port, and the third feed port can also be provided with a metering pump or other components for controlling the feeding amount. For example, the first feed port can be used for feeding acetone, the second feed port can be used for feeding isobutyraldehyde, and the third feed port can be used for feeding organic bases.

[0045] Preferably, a metering pump is provided between the premixed raw material inlet and the premixed raw material outlet, and the premixed raw material inlet is located at the top of the fixed bed reaction unit.

[0046] In which, further, the fixed bed reaction unit is a trickle bed reactor, the trickle bed reactor has a catalyst bed layer, and the catalyst bed layer has a heating element.

[0047] Furthermore, the device further comprises a recovery unit, which is connected to the fixed bed reaction unit and is used to recover methyl isobutyl ketone.

[0048] In another aspect of the present invention, the present invention provides a methyl isoamyl ketone obtained by the above method or the above device. In general, the MIAK obtained by the above method or device has at least one of the advantages of high conversion rate, simple process flow, low production cost, easy separation of side reaction products, and high product purity.

[0049] The present invention has at least one of the following beneficial effects:

[0050] The condensation catalyst can improve the selectivity of the aldol condensation and more effectively avoid the condensation reaction of acetone and isobutyraldehyde themselves;

[0051] Organic amines have good solubility in reactants (acetone and isobutyraldehyde), and there is no need to add a large amount of aqueous solvent, which can reduce the generation of alkaline wastewater;

[0052] Under the combined action of the condensation catalyst and the hydrogenation catalyst, the conversion rate of isobutyraldehyde is high, the content of methyl isobutyl ketone in the product is low, and the selectivity of isobutyraldehyde to methyl isoamyl ketone is also improved, so the post-treatment process is relatively simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0054] Figure 1 This is a schematic structural diagram of an apparatus for preparing methyl isoamyl ketone according to an embodiment of the present invention;

[0055] Figure 2 and Figure 3 The gas chromatography test results of the sample obtained in Example 1 of the present invention;

[0056] Figure 4 and Figure 5 This is the gas chromatography test result of the sample obtained in Example 2 of the present invention.

[0057] Explanation of the reference numerals: 100 - raw material premixing unit; 110 - first feed port; 120 - second feed port; 130 - third feed port; 140 - premixed raw material outlet; 200 - fixed bed reaction unit; 210 - premixed raw material inlet; 220 - reducing gas inlet; 230 - methyl isoamyl ketone outlet; 310 - reducing gas storage tank; 320 - carrier gas storage tank. DETAILED DESCRIPTION

[0058] In order to more clearly understand the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now further described in detail. It should be understood that the following specific embodiments are only exemplary, and the technical solution of the present invention is not limited to the specific embodiments listed below. As those skilled in the art can appreciate, the described embodiments can be modified in various ways without departing from the spirit or scope of the present application.

[0059] refer to Figure 1 The device for preparing methyl isoamyl ketone includes a raw material premixing unit 100 and a fixed bed reaction unit 200, wherein the raw material premixing unit 100 is used to mix the raw materials required for synthesizing methyl isoamyl ketone, and the raw materials may include acetone, isobutyraldehyde and a condensation catalyst, and the condensation catalyst includes an organic base. The fixed bed reaction unit 200 is fluidically connected to the raw material premixing unit 100, and is filled with a hydrogenation catalyst. The device is used to react acetone and isobutyraldehyde under the catalysis of a condensation catalyst and a hydrogenation catalyst in the presence of hydrogen to obtain the methyl isoamyl ketone.

[0060] Wherein, the raw material premixing unit 100 includes a first feed port 110, a second feed port 120, a third feed port 130 and a premixed raw material outlet 140, and the fixed bed reaction unit 200 has a premixed raw material inlet 210, a reducing gas inlet 220 and a methyl isoamyl ketone outlet 230, and the premixed raw material inlet 210 is connected to the premixed raw material outlet 140, and the fixed bed reaction unit 200 is filled with a hydrogenation catalyst. The first feed port 110 is used for feeding acetone, the second feed port 120 is used for feeding isobutyraldehyde, and the third feed port 130 is used for feeding organic bases. In other embodiments, the raw material premixing unit 100 may include only two feed ports (not shown in the figure) and a premixed raw material outlet 140. For example, the raw material premixing unit 100 can be used to mix acetone and isobutyraldehyde, and the organic base can be added to the fixed bed reaction unit 200 separately.

[0061] Among them, a metering pump is provided between the premixed raw material inlet 210 and the premixed raw material outlet 140, and the premixed raw material inlet 210 is located at the top of the fixed bed reaction unit 200. The reducing gas inlet 220 is connected to the reducing gas storage tank 310 and the carrier gas storage tank 320, and is used to supply reducing gas to the fixed bed reaction unit 200, or to introduce an inert carrier gas such as nitrogen to replace the oxygen contained in the fixed bed reaction device. The reducing gas inlet 220 and the premixed raw material inlet 210 are both located at the top of the fixed bed reaction unit 200, which can further improve the efficiency of the device in generating MIAK by reaction.

[0062] Among them, the fixed bed reaction unit 200 is a trickle bed reactor. The trickle bed reactor has a catalyst bed, and the catalyst bed has a heating element. More specifically, the trickle bed reactor can accommodate a spherical or sheet Pd / C catalyst with a volume of 40-50% of the liquid volume, and the catalyst bed is filled with inert fillers above and below, and the hydrogenation catalyst is filled in the middle of the inert fillers. In order to improve the heat conduction efficiency and the heat transfer effect, the catalyst bed can be heated in three stages, with a thyristor temperature control and a thermocouple as a temperature measuring element. The reaction product can be discharged and collected through the methyl isoamyl ketone outlet 230 located at the bottom of the fixed bed reaction unit 200. Specifically, the trickle bed reactor is made of a Φ22×500mm pressure-resistant stainless steel pipe, with threaded seals at both ends, and the volume of the reactor can accommodate approximately 100mL of liquid raw materials. The trickle bed reactor is filled with 50mL of spherical Pd / C catalyst, and the catalyst bed is filled with 50mL of inert fillers above and below.

[0063] The device also includes a recovery unit which is connected to the fixed bed reaction unit 200 and is used to recover methyl isobutyl ketone.

[0064] The method proposed in the present invention is described in detail below through specific examples. The methods used in the following examples are conventional methods unless otherwise specified, and the reagents used are commercially available reagents unless otherwise specified.

[0065] Example 1

[0066] A certain amount of solid granular palladium-carbon catalyst (specific surface area 1200 m 2 / g, the carrier is coconut shell activated carbon, the carrier particle size is 8 mesh, the palladium particle size is 3.5-5nm, and the palladium content is 0.3%), the catalyst bed filling height is 40cm, the hydrogen cylinder is opened to replace the air 6 times, the reaction device is heated, and after the temperature reaches 105°C, hydrogen is introduced and the tail gas is adjusted through the back pressure valve to control the hydrogen pressure to 2.5MPa, the tail gas flow rate is 30mL / min, and a 12% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump at a flow rate of 0.18mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a rate of 1.5mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution and isobutyraldehyde in the system is 0.04:1. The liquid air velocity of the reactants is 2.0h -1 The system pressure was 2.5 MPa, the reaction temperature was 105°C, and samples were taken for analysis after the reaction liquid reached the space velocity volume, that is, after the reaction lasted for 30 minutes.

[0067] It should be noted that, in the present invention, the term "liquid space velocity" is a parameter of the residence time of the reaction liquid in the reactor, and the reciprocal of the liquid space velocity is the residence time of the reactants in the reactor.

[0068] Gas chromatography (GC) was used to detect the components in the reaction liquid and the finished product (the reaction liquid was obtained by sequentially treating the water phase, the distillation tower and the dehydration tower). Figure 2 as well as Figure 3 , most of the components in the reaction liquid are excess acetone (RT (i.e., the time [min] shown on the horizontal axis of the figure) 3.003, peak area accounting for 40.11%) and MIAK (RT5.706, peak area accounting for 50.98%). The peak area of ​​MIAK in the finished product accounts for as high as 99.42%. According to GC determination, the conversion rate of isobutyraldehyde is 98.94%, the residual amount of isobutyraldehyde is ≤1.2%, the content of methyl isobutyl ketone (MIBK) is 0.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) is 92.12%.

[0069] Note: The calculation method of isobutylaldehyde (IBD) conversion and MIAK selectivity is:

[0070] Molar conversion of IBD = (moles of isobutyraldehyde in the raw material - moles of isobutyraldehyde in the product) / moles of isobutyraldehyde in the raw material;

[0071] The molar selectivity of MIAK = (the number of moles of MIAK in the product) / (the number of moles of isobutyraldehyde in the feed - the number of moles of isobutyraldehyde in the product).

[0072] Example 2

[0073] A certain amount of solid granular palladium-carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 0.5% and the carrier particle size is 7 mesh) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 98°C, hydrogen is introduced and the tail gas is adjusted by the back pressure valve. The hydrogen pressure is controlled to be 2.5MPa, and the tail gas flow rate is 60mL / min. A 10% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump, and the flow rate is 0.16mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 2.0mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution to isobutyraldehyde in the system is 0.025:1, and the liquid air velocity of the reactant is 2.6h- 1 The system pressure was 2.5 MPa, the reaction temperature was 98°C, and the reaction liquid was sampled and analyzed after reaching the liquid space velocity volume, that is, after reacting for 23 minutes.

[0074] Gas chromatography (GC) was used to detect the components in the reaction liquid and the finished product (the reaction liquid was obtained by sequentially treating the water phase, the distillation tower and the dehydration tower). Figure 4 as well as Figure 5 , most of the components in the reaction liquid are excess acetone (RT3.003, peak area accounts for 40.46%) and MIAK (RT5.706, peak area accounts for 52.27%). The peak area of ​​MIAK in the finished product accounts for as high as 99.22%. According to GC determination, the conversion rate of isobutyraldehyde is 99.95%, the residual amount of isobutyraldehyde is ≤0.1%, the content of methyl isobutyl ketone (MIBK) is 0.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) is 92.56%.

[0075] Example 3

[0076] A certain amount of solid granular palladium carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 1.5% and the carrier particle size is 7 mesh) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 90°C, hydrogen is introduced and the tail gas is adjusted through the back pressure valve. The hydrogen pressure is controlled to be 2.5MPa, and the tail gas flow rate is 100mL / min. A 5% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump at a flow rate of 0.2mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 1.5mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution to isobutyraldehyde in the system is 0.02:1, and the liquid air velocity of the reactant is 2.04h -1 The system pressure was 2.5 MPa, the reaction temperature was 90°C, and sampling and analysis were performed after the reaction liquid reached the space velocity volume, that is, after the reaction time of 29.4 min.

[0077] Gas chromatography (GC) was performed on the reaction liquid and the components in the finished product. According to GC determination, the isobutyraldehyde conversion rate was 99.9%, the residual amount of isobutyraldehyde was ≤0.1%, the content of methyl isobutyl ketone (MIBK) was 0.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 92.83%.

[0078] Example 4

[0079] A certain amount of solid granular palladium carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 1.0% and the carrier particle size is 6 mesh) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 100°C, hydrogen is introduced and the tail gas is adjusted through the back pressure valve. The hydrogen pressure is controlled to be 2.5MPa, and the tail gas flow rate is 40mL / min. A 3% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump, and the flow rate is 0.4mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 1.5mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution to isobutyraldehyde in the system is 0.02:1, and the liquid air velocity of the reactant is 2.28h -1 The system pressure was 2.5 MPa, the reaction temperature was 100°C, and samples were taken for analysis after the reaction liquid reached the space velocity volume, that is, after the reaction lasted for 26.4 minutes.

[0080] Gas chromatography (GC) was performed on the reaction liquid and the components in the finished product. According to GC determination, the isobutyraldehyde conversion rate was 99.98%, the residual amount of isobutyraldehyde was ≤0.1%, the content of methyl isobutyl ketone (MIBK) was 0.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 92.72%.

[0081] Example 5

[0082] A certain amount of solid granular palladium carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 0.8% and the carrier particle size is 6 mesh) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 145°C, hydrogen is introduced and the tail gas is adjusted through the back pressure valve. The hydrogen pressure is controlled to be 2.5MPa, and the tail gas flow rate is 150mL / min. A 15% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump at a flow rate of 0.3mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 1.5mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution to isobutyraldehyde in the system is 0.09:1, and the liquid air velocity of the reactant is 2.16h -1The system pressure was 2.5 MPa, the reaction temperature was 145°C, and samples were taken for analysis after the reaction liquid reached the space velocity volume, that is, after the reaction lasted for 27.6 minutes.

[0083] Gas chromatography (GC) was performed on the reaction liquid and the components in the finished product. According to GC determination, the isobutyraldehyde conversion rate was 99.90%, the residual amount of isobutyraldehyde was ≤0.1%, the content of methyl isobutyl ketone (MIBK) was 0.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 91.18%.

[0084] Example 6

[0085] A certain amount of solid granular palladium carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 0.3%) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 125°C, hydrogen is introduced and the tail gas is adjusted by the back pressure valve. The hydrogen pressure is controlled to be 2.0 MPa, and the tail gas flow rate is 30 mL / min. A 6% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump, and the flow rate is 0.38 mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 3.0 mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution to isobutyraldehyde in the system is 0.02:1, and the liquid air velocity of the reactants is 4.0 h -1 The system pressure was 2.0 MPa, the reaction temperature was 125°C, and the reaction liquid was sampled and analyzed after reaching the space velocity volume, that is, after reacting for 15 minutes.

[0086] Gas chromatography (GC) was performed on the reaction liquid and the components in the finished product. According to GC determination, the isobutyraldehyde conversion rate was 99.92%, the residual amount of isobutyraldehyde was ≤0.1%, the content of methyl isobutyl ketone (MIBK) was 0.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 92.98%.

[0087] Example 7

[0088] A certain amount of solid granular platinum carbon catalyst (the other parameters are the same as those in Example 1, except that the platinum content is 0.1%) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 90°C, hydrogen is introduced and the tail gas is adjusted through the back pressure valve. The hydrogen pressure is controlled to be 2.4MPa, and the tail gas flow rate is 60mL / min. A 3.0% tetramethylammonium hydroxide aqueous solution is injected into the system with a metering pump at a flow rate of 0.5mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 1.5mL / min. The molar ratio of tetramethylammonium hydroxide aqueous solution to isobutyraldehyde in the system is 0.03:1, and the liquid air velocity of the reactants is 2.4h -1 The system pressure was 2.4 MPa, the reaction temperature was 90°C, and sampling and analysis were performed after the reaction liquid reached the space velocity volume, that is, after the reaction lasted for 24.9 minutes.

[0089] The reaction liquid and components in the finished product were detected by gas chromatography (GC). GC determination showed that the isobutyraldehyde conversion rate was 100%, the methyl isoamyl alcohol (MIAC) content was 3.5%, the methyl isobutyl ketone (MIBK) content was 1.5%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 82%.

[0090] Comparative Example 1

[0091] A certain amount of solid granular palladium carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 0.5%) is loaded into the trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 120°C, hydrogen is introduced and the tail gas is adjusted by the back pressure valve. The hydrogen pressure is controlled to be 3.0 MPa, and the tail gas flow rate is 90 mL / min. A 3.5% sodium hydroxide aqueous solution is injected into the system with a metering pump, and the flow rate is 0.25 mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 1.5 mL / min. The molar ratio of sodium hydroxide aqueous solution to isobutyraldehyde in the system is 0.04:1, and the liquid air velocity of the reactant is 2.1 h -1 The system pressure was 3.0 MPa, the reaction temperature was 120°C, and samples were taken for analysis after the reaction liquid reached the space velocity volume, that is, after the reaction lasted for 28.6 minutes.

[0092] Gas chromatography (GC) was used to detect the components in the reaction liquid and the finished product. According to GC determination, the isobutyraldehyde conversion rate was 99.5%, the residual amount of isobutyraldehyde was ≤0.5%, the content of methyl isobutyl ketone (MIBK) was 0.52%, the unknown high-boiling point material was 2.62%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 87.5%.

[0093] Comparative Example 2

[0094] A certain amount of solid granular palladium-carbon catalyst (the other parameters are the same as those in Example 1, except that the palladium content is 0.5%) is loaded into a trickle bed reactor, and the catalyst bed filling height is 40 cm. The hydrogen cylinder is opened to replace the air 6 times, and the reaction device is heated. After the temperature reaches 130°C, hydrogen is introduced and the tail gas is adjusted through a back pressure valve. The hydrogen pressure is controlled to be 1.5MPa, and the tail gas flow rate is 60mL / min. Triethylammonium is injected into the system with a metering pump at a flow rate of 0.6mL / min. At the same time, a mixed solution of acetone and isobutyraldehyde (3:1 molar ratio) is pumped into the system at a speed of 1.5mL / min. The molar ratio of triethylamine to isobutyraldehyde in the system is 0.85:1, and the liquid air velocity of the reactants is 2.52h -1 The system pressure was 1.5 MPa, the reaction temperature was 130°C, and samples were taken for analysis after the reaction liquid reached the space velocity volume, that is, after the reaction lasted for 23.8 minutes.

[0095] Gas chromatography (GC) was performed on the reaction liquid and the components in the finished product. According to GC determination, the isobutyraldehyde conversion rate was 85%, the residual amount of isobutyraldehyde was ≤0.1%, the content of methyl isobutyl ketone (MIBK) was 1%, and the selectivity of isobutyraldehyde to methyl isoamyl ketone (MIAK) was 62%.

[0096] According to a specific embodiment of the present invention, the method for preparing MIAK can achieve a conversion rate of isobutyraldehyde of not less than 98.8%, a residual amount of isobutyraldehyde in the product can reach ≤1.2%, a content of methyl isobutyl ketone (MIBK) in the product is not higher than 1.5%, and the selectivity of isobutyraldehyde to the methyl isoamyl ketone is not lower than 82%. In addition, the side reaction product components in the reaction product are simple and easy to separate, a small amount of methyl isobutyl ketone is generated during the reaction, and the product is further separated and purified to obtain MIBK with a purity of more than 99%. The obtained MIBK has good quality and can be used in the antioxidant 6PPD position, that is, the discharge of three wastes is reduced, and the production cost can be further reduced. Further, the separation and purification can be to add water phase to the liquid after the reaction to obtain an aqueous phase and an organic phase. The aqueous phase contains an organic base, which can be used as a condensation catalyst for recycling. The organic phase enters a distillation tower for distillation treatment, recovers the unreacted acetone, and the acetone material obtained at the top of the tower is returned for recycling. The bottom material obtained from the distillation tower enters the dehydration tower for further processing, and MIBK with a purity of more than 99% can be obtained at the top of the tower. The bottom material of the dehydration tower has been dehydrated, and MIAK can be obtained by further distillation and other operations.

[0097] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive.

[0098] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing methyl isoamyl ketone, characterized in that: In the presence of hydrogen, acetone and isobutyraldehyde are reacted under the catalysis of a condensation catalyst and a hydrogenation catalyst to obtain the methyl isoamyl ketone. The condensation catalyst is a quaternary ammonium hydroxide aqueous solution, and the molar ratio of the quaternary ammonium hydroxide to the isobutylaldehyde is (0.02-0.15):1; The quaternary ammonium base is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

2. The method according to claim 1, characterized in that The method satisfies at least one of the following conditions: The condensation catalyst is an aqueous solution containing 3 to 15 wt % of the quaternary amine base; The molar ratio of the acetone to the isobutyraldehyde is (1-5):1; The molar ratio of the quaternary ammonium base to the isobutyraldehyde is (0.02-0.1):

1.

3. The method according to claim 1, characterized in that The condensation catalyst is an aqueous solution containing 3-6 wt % of the quaternary amine base.

4. The method according to claim 1, characterized in that: The condensation catalyst is an aqueous solution containing 10-15 wt % of the quaternary amine base.

5. The method according to claim 1, characterized in that The hydrogenation catalyst includes a carrier and an active metal supported on the carrier.

6. The method according to claim 5, characterized in that The hydrogenation catalyst satisfies at least one of the following conditions: The mass percentage of the active metal relative to the mass of the carrier is 0.1-5%; The carrier is coconut shell activated carbon; The particle size of the carrier is 6-8 mesh; The specific surface area of ​​the hydrogenation catalyst is not less than 1000 m 2 / g; The active metal is at least one of platinum, palladium, nickel and copper; The particle size of the active metal is 3.5-10 nm.

7. The method according to claim 5, characterized in that The particle size of the active metal is 3.5-6 nm.

8. The method according to claim 5, characterized in that The particle size of the active metal is 3.5-5 nm.

9. The method according to claim 1, characterized in that: The method satisfies at least one of the following conditions: The reaction temperature is 50-150°C; The pressure of the hydrogen is 1.0-4.0 MPa; The acetone, the isobutyraldehyde and the condensation catalyst are supplied to the reaction device at a rate of 0.1 to 3 mL / min, respectively and independently; The reaction device of the reaction is a trickle bed reactor, and the reactants are heated at a liquid space velocity of 0.1-5.0 h -1 The exhaust gas is supplied to the reaction device at a rate of 0 to 200 mL / min.

10. The method according to claim 1, characterized in that The reaction temperature is 65-145°C.

11. The method according to claim 1, characterized in that: The pressure of the hydrogen is 2.0-3.0 MPa.

12. The method according to claim 1, characterized in that The acetone and the isobutyraldehyde are supplied to the reaction device at a rate of 1.5 to 3 mL / min; the condensation catalyst is supplied to the reaction device at a rate of 0.15 to 0.5 mL / min.

13. The method according to claim 9, characterized in that The reactants are heated at a liquid space velocity of 2 to 4 h -1 The tail gas is supplied to the reaction device; the tail gas flow rate is 30-150 mL / min.

14. The method according to any one of claims 1 to 13, characterized in that: The method satisfies at least one of the following conditions: The conversion rate of the isobutyraldehyde is not less than 98.8%; The residual amount of isobutyraldehyde in the product is ≤1.2%; The content of methyl isobutyl ketone in the product is not higher than 1.5%; The selectivity of the isobutyraldehyde to the methyl isoamyl ketone is not less than 82%.

15. The method according to claim 14, characterized in that The content of methyl isobutyl ketone in the product is not higher than 0.6%.

16. The method according to claim 14, characterized in that The selectivity of the isobutyraldehyde to the methyl isoamyl ketone is not less than 91%.

17. The method according to claim 14, characterized in that The selectivity of the isobutyraldehyde to the methyl isoamyl ketone is not less than 92%.

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