Method for preparing multi-carbon methyl ketone from acetone

Abstract

The invention provides a method for preparing multi-carbon methyl ketone from acetone. According to the method, acetone or acetone reacts with corresponding aldehyde to obtain the multi-carbon methyl ketone, in order to improve the yield of the multi-carbon methyl ketone, acetone with the methanol content smaller than or equal to 250 ppm, preferably smaller than or equal to 200 ppm is used for reaction, and after acetone is recycled, the concentration of methanol entering a reactor is smaller than or equal to 1.5%, so that the selectivity of acetone relative to the multi-carbon methyl ketone is larger than or equal to 90%. The method is simple in technological process, good in product selectivity and high in device economy.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and in particular relates to a method for preparing multi-carbon methyl ketone from acetone. Technical Background

[0002] Methyl ketone compounds are commonly used organic synthesis intermediates. The preparation methods include olefin oxidation, alkyne hydration and aldehyde-ketone aldol condensation. Among them, methyl isobutyl ketone (MIBK) and methyl isoamyl ketone (MIAK) are widely used in fine chemicals, rubber antioxidants and other chemical fields. They are prepared by aldehyde-ketone aldol condensation in industry. Acetone can produce MIBK through condensation dehydration hydrogenation reaction, and acetone and isobutyraldehyde can produce MIAK through condensation dehydration hydrogenation reaction.

[0003] In addition, other methyl ketone compounds can also be prepared by this method, such as methyl isohexyl ketone (prepared from acetone and 3-methylbutanal), methyl isoheptyl ketone (prepared from acetone and 4-methylpentanal), methyl isooctyl ketone (prepared from acetone and 5-methylhexanal), and methyl isononyl ketone (prepared from acetone and 6-methylheptanal).

[0004] These methyl ketone compounds can be obtained through a one-step method and a multi-step method. The one-step method can react under the catalysis of a noble metal-acidic resin, and the multi-step method can undergo a condensation dehydration reaction under the catalysis of an acidic or alkaline catalyst, and then hydrogenate under the catalysis of a hydrogenation catalyst (such as platinum, palladium, nickel, copper, etc.) to obtain the product.

[0005] Patent CN200610045641.4 discloses a method for preparing a palladium / resin catalyst for one-step reaction of acetone to produce MIBK products; CN00110591.4 discloses a method for separating the reaction product of acetone to synthesize methyl isobutyl ketone to obtain qualified MIBK products. However, the effect of impurities in acetone on the reaction is not mentioned.

[0006] Patents CN202011199013.8 and CN202011635892.4 disclose a method for synthesizing methyl isoamyl ketone. The former patent uses a palladium / phosphonic acid resin catalyst to catalyze the reaction of acetone and isobutyraldehyde to generate methyl isoamyl ketone in a one-step process. The latter patent first catalyzes the condensation and dehydration of acetone and isobutyraldehyde through a phosphonic acid resin, and then hydrogenates through a hydrogenation catalyst to generate methyl isoamyl ketone. However, the single-pass conversion rate of acetone and isobutyraldehyde is low, and a large amount of MIBK is generated. Patent CN202310448388.0 discloses an apparatus and method for preparing methyl isoamyl ketone, which uses an organic base as a catalyst to catalyze the reaction of acetone and isobutyraldehyde, and then reacts under the catalysis of a hydrogenation catalyst to generate methyl isoamyl ketone. The selectivity of isobutyraldehyde to methyl isoamyl ketone is greater than 92%, but it requires a two-step reaction, and the process flow is complicated.

[0007] In view of the above problems, it is necessary to develop a new production method of methyl ketone compounds so that the product selectivity is high and the process flow is simple. Summary of the invention

[0008] The object of the present invention is to provide a method for preparing multi-carbon methyl ketone from acetone. The process flow of the present invention is simple and the product selectivity is high.

[0009] Another object of the present invention is to provide a method for preparing multi-carbon methyl ketones from acetone, wherein the product selectivity can be controlled.

[0010] The present invention is achieved through the following technical solutions:

[0011] A method for preparing a multi-carbon methyl ketone from acetone, wherein acetone is reacted by itself or with a corresponding aldehyde under the action of a catalyst to obtain a multi-carbon methyl ketone of the following formula:

[0012]

[0013] When n=1, that is, the product is methyl isobutyl ketone, the raw materials are acetone and hydrogen, and the reaction that occurs is as shown in Formula 1.

[0014]

[0015] When n=2, that is, the product is methyl isoamyl ketone, the raw materials are acetone and isobutyraldehyde, and the reaction that occurs is shown in Formula 2.

[0016]

[0017] When n=3-6, that is, when the product is the corresponding multi-carbon methyl ketone, the raw materials are acetone and the corresponding aldehyde, and the reaction that occurs is as shown in Formula 3.

[0019]

[0020] Usually, when n=1, in order to ensure the life of the catalyst and improve the product selectivity, the acetone per-pass conversion rate is generally controlled to be 10%-80%, and the unreacted acetone will be recycled by distillation; when n=2-6, in order to ensure the conversion rate of the aldehyde, it is necessary to keep the acetone in the raw material in excess, and the unreacted acetone will also be recycled by distillation. The acetone used in industry is generally a superior product with an acetone purity of ≥99.5%, but since most industrial acetone is produced by phenol-ketone devices and contains methanol, the inventors found that the presence of methanol will affect the conversion rate of acetone and the selectivity of multi-carbon methyl ketones. Since acetone and methanol are azeotropic, if the methanol content in acetone exceeds 250ppm, methanol will accumulate during the acetone recycling process, and the cumulative concentration exceeds 1.5%. Since methanol and acetone undergo aldol condensation under the action of the catalyst to form ketal or hemiketal, the α-H activity of acetone is reduced. On the one hand, it affects the condensation activity of acetone with other aldehydes and ketones, thereby affecting the single-pass conversion rate of the reaction; on the other hand, the reduced α-H activity of acetone makes it easier for acetone to undergo hydrogenation reaction with hydrogen adsorbed on the catalyst to form isopropanol, thereby affecting the selectivity of multi-carbon methyl ketones.

[0021] Therefore, in order to improve the yield of multi-carbon methyl ketone, the present invention uses acetone with a methanol content of less than or equal to 250 ppm, preferably less than or equal to 200 ppm, and more preferably less than 100 ppm for the reaction, and the methanol content in the acetone is greater than 0; in addition, the purity of the acetone is above 99%, preferably above 99.5%.

[0022] In the present invention, by controlling the content of methanol in acetone to be ≤250ppm, the methanol concentration entering the reactor after acetone reuse is made ≤1.5%, thereby making the selectivity of multi-carbon methyl ketone ≥90%. The method for controlling the methanol content in acetone can be: on the one hand, through reaction control, industrial acetone mainly comes from the phenol-ketone device, cumene and air undergo oxidation reaction to generate phenol and acetone, cumene will generate a small amount of dimethyl benzyl alcohol during oxidation, and dimethyl benzyl alcohol decomposition will produce acetophenone and methanol, so optimizing the reaction conditions (such as temperature, pressure, etc.) of the oxidation unit can reduce the generation of byproduct dimethyl benzyl alcohol, thereby reducing the generation of methanol. On the other hand, the methanol content can be controlled by a purification method, and the raw material acetone is subjected to extractive distillation to remove methanol therein, and pure water can be selected as the extractant.

[0023] In the present invention, the catalyst used is a metal-carrier bifunctional catalyst, wherein the metal is at least one of the noble metals, such as Pd, Pt, Ru, Rh, Ir, Os, preferably at least one of Pd, Pt and Ru; the carrier is a carrier containing acidic sites, such as acidic resins (such as sulfonic acid resins, phosphoric acid resins, etc.), acidic oxides (such as alumina, etc.), molecular sieves (such as Hβ molecular sieves, HZSM-5 molecular sieves, etc.), activated carbon, solid superacids (such as fluorosulfonic acid resins, etc.), clays, heteropolyacids (such as phosphotungstic heteropolyacids, etc.), diatomaceous earth, kaolin, etc.;

[0024] Preferably, based on the total mass of the catalyst, the content of the metal active component in the catalyst is 0.1wt%-2wt%, and the content of the carrier is 98wt%-99.9wt%;

[0025] In the present invention, the catalyst may be a commercial catalyst or a self-made catalyst, wherein the preparation method of the self-made catalyst is an impregnation method, preferably, the method comprises the following steps: preparing a hydrochloride or nitrate of an active component into an aqueous solution of a certain concentration to prepare a precursor solution; weighing a certain amount of a carrier, adding the carrier to the precursor solution, stirring at 10°C-80°C for 2h-10h, filtering the precipitate, washing it with deionized water, and drying it at 80°C-200°C for 2h-24h, preferably at a drying temperature of 100-150°C, to obtain a catalyst loaded with the corresponding active component;

[0026] In the present invention, preferably, the pore size of the catalyst is 0.1nm-50nm, and the specific surface area is 5m 2 / g-600m 2 / g.

[0027] In the present invention, the reactor used is a tank reactor or a fixed bed reactor, and the reaction can be a continuous reaction or an intermittent reaction. A continuous fixed bed reactor is preferred.

[0028] In the present invention, the reaction temperature is 70°C-250°C, preferably 90°C-200°C; the reaction pressure is 0.5MPa-5MPa, preferably 2MPa-5MPa; the space velocity of the reaction raw materials (excluding air) is 0.1h -1 -5h -1 , preferably 0.5h -1 -3h -1 ;;The hydrogen-to-oil ratio (molar ratio of hydrogen to organic components) is 0.1-5, preferably 0.5-3. Wherein, when n=2-6, the reaction raw materials are acetone and polycarbon aldehyde, and the molar ratio of acetone to polycarbon aldehyde is 1.01-3.

[0029] In the present invention, the reaction liquid first passes through a light-removal tower to remove light components generated during the reaction, such as 2-methylpentane, and then passes through an acetone recovery tower to recover unreacted acetone;

[0030] In the present invention, the lightness removal tower is operated under an absolute pressure of 50-500 KPa, preferably 100-200 KPa; the number of theoretical plates is 10-60 plates, preferably 20-50 plates; the feed position is the 5th to 40th plate (counted from top to bottom), preferably the 10th to 30th plate; the reflux ratio is 1-20, preferably 3-15; the tower top temperature is 10°C-150°C, and the tower bottom temperature is 30°C-150°C;

[0031] In the present invention, the acetone recovery tower is operated under an absolute pressure of 30-200 KPa, preferably 50-100 KPa; the number of theoretical plates is 20-60 plates, preferably 30-50 plates; the feed position is the 8th to 40th plate, preferably the 10th to 30th plate (counted from top to bottom); the reflux ratio is 0.1-5, preferably 0.5-2; the tower top temperature is 10°C-90°C, and the tower bottom temperature is 30°C-250°C.

[0032] Another aspect of the present invention provides a method for controlling the selectivity of multi-carbon methyl ketones. According to the above-mentioned reaction conditions, by adjusting the content of methanol in acetone, the selectivity of acetone to multi-carbon methyl ketones and the content of methanol in acetone meet the following formula:

[0033]

[0034] Where S is the selectivity of acetone to multi-carbon methyl ketone, unit %

[0035] a is the content of methanol in acetone, unit PPm, a≤250, preferably a≤200

[0036] x is the acetone conversion rate, unit is %, 10≤x≤80, preferably 30≤x≤80.

[0037] Compared with the prior art, the present invention has the following positive effects:

[0038] By controlling the methanol content in acetone, the methanol content in the acetone entering the reactor is controlled to be ≤1.5%, thereby reducing the influence of methanol on the α-H activity of acetone, thereby improving the acetone conversion rate; and the activity of direct hydrogenation of acetone can be appropriately inhibited, thereby improving the selectivity of multi-carbon methyl ketones. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0040] The main raw material information is as follows:

[0041]

[0042]

[0043] The device information is as follows:

[0044]

[0045] The gas chromatography analysis conditions are:

[0046] Analytical instrument: Shimadzu HP-PONA (specifications: 50m×0.2mm×0.5μm);

[0047] Gas phase analysis method: correction normalization method;

[0048] Gas phase analysis conditions: vaporization chamber temperature was 230°C, detector temperature was 300°C, and column temperature was programmed: 40°C, 8 min; 10°C / min to 240°C.

[0049] The catalyst compositions in each example are shown in Table 1, and the specific preparation methods are shown in each example.

[0050] Table 1 Catalyst composition in each example

[0051]

[0052] The conditions of the reactor in each example are shown in Table 2.

[0053] Table 2 Reactor conditions in each example

[0054] Example 2 Example 3 Example 4 Example 5 Reaction temperature, °C 180 70 100 250 Reaction pressure, Mpa 0.5 5 3 2 Hydrogen to oil ratio, mol / mol 0.1 5 1 2 <![CDATA[Space velocity, h -1 > 5 0.1 1.3 3 Acetone to aldehyde ratio, mol / mol 3 2 -- 1.01

[0055] The conditions of the lightness removal tower in each embodiment are shown in Table 3.

[0056] Table 3 Conditions of the light removal tower in each embodiment

[0057]

[0058]

[0059] The conditions of the acetone recovery tower in each embodiment are shown in Table 4.

[0060] Table 4 Acetone recovery tower conditions in each embodiment

[0061] Acetone recovery tower Example 2 Example 3 Example 4 Example 5 Pressure, KPa 30 200 80 100 Theoretical plate number 20 60 40 50 Feeding position 8 40 25 30 Reflux ratio 0.1 5 2 3 Tower top temperature, °C 24.4 76.5 49.4 55.9 Bottom temperature, ℃ 65.5 143.2 76.0 144.3

[0062] Example 1

[0063] 3.33 parts of PdCl2 were prepared into a 1% aqueous solution to prepare a precursor solution; 98 parts of alumina were weighed and added to the 1% PdCl2 aqueous solution, stirred at 10°C for 10 hours, the precipitate obtained by filtration was dried at 200°C for 2 hours, and then a catalyst powder loaded with PdCl2 was obtained; then tableting and crushing were performed, and the catalyst with a mesh size of 10-40 was sieved out to obtain catalyst 1.

[0064] 1.73 parts of PtCl4 were prepared into a 1% aqueous solution to prepare a precursor solution; 99 parts of activated carbon were weighed and added into a 1% PtCl4 aqueous solution, stirred at 80°C for 2 hours, the precipitate obtained by filtration was dried at 150°C for 15 hours, and then a catalyst powder loaded with PtCl4 was obtained; then the catalyst powder was pressed into tablets, crushed, and the catalyst with a mesh size of 10-40 was sieved out to obtain catalyst 2.

[0065] Catalyst 3 is purchased DuPont catalyst CH28, in which the palladium content is 0.7% (dry basis) and the carrier is sulfonic acid resin.

[0066] 0.21 parts of RuCl3 were prepared into a 1% aqueous solution to prepare a precursor solution; 99.9 parts of Hβ molecular sieve were weighed and added to the 1% RuCl3 aqueous solution, stirred at 60°C for 8 hours, the precipitate obtained by filtration was dried at 80°C for 24 hours, and then a catalyst powder loaded with RuCl3 was obtained; then tableting and crushing were performed, and the catalyst with a mesh size of 10-40 was sieved out to obtain catalyst 4.

[0067] Example 2

[0068] The fixed bed reactor was loaded with catalyst 1. The conditions of the reactor were as shown in Table 2. Acetone and 6-methylheptanal were introduced into the reactor in a molar ratio of 3:1, wherein the purity of acetone was 99.71% and the content of methanol was 100 ppm. After the reaction, a reaction solution 1 was obtained. The light components generated by the reaction were removed from the reaction solution 1 according to the conditions in Table 3, and then the unreacted acetone was recovered according to the conditions in Table 4. The final acetone conversion rate was 35.83%, and the selectivity of acetone to methyl isononyl ketone was 92.48%.

[0069] Example 3

[0070] The fixed bed reactor was loaded with catalyst 2. The conditions of the reactor were as shown in Table 2. Acetone and 4-methylvaleraldehyde were introduced into the reactor in a molar ratio of 2:1, wherein the purity of acetone was 99.78%, and the content of methanol was 200 ppm. After the reaction, a reaction solution 2 was obtained. The light components generated by the reaction were removed from the reaction solution 2 according to the conditions in Table 3, and then the unreacted acetone was recovered according to the conditions in Table 4. The final acetone conversion rate was 48.91%, and the selectivity of acetone to methyl isoheptyl ketone was 90.55%.

[0071] Example 4

[0072] The fixed bed reactor was loaded with catalyst 3. The conditions of the reactor were as shown in Table 2. Acetone entered the reactor, wherein the acetone purity was 99.63% and the methanol content was 50 ppm. After the reaction, reaction liquid 3 was obtained. The light components generated by the reaction were removed from the reaction liquid 3 according to the conditions in Table 3, and then the unreacted acetone was recovered according to the conditions in Table 4. The final acetone conversion rate was 38.72%, and the selectivity of acetone to methyl isobutyl ketone was 93.25%.

[0073] Example 5

[0074] The fixed bed reactor was loaded with catalyst 4. The conditions of the reactor were as shown in Table 2. Acetone and isobutyraldehyde were introduced into the reactor in a molar ratio of 1.01:1. The purity of acetone was 99.83%, and the content of methanol was 80 ppm. After the reaction, a reaction liquid 4 was obtained. The light components generated by the reaction were removed from the reaction liquid 4 according to the conditions in Table 3. Unreacted acetone was recovered according to the conditions in Table 4. The final acetone conversion rate was 78.18%, and the selectivity of acetone to methyl isoamyl ketone was 90.69%.

[0075] Comparative Example 1

[0076] Compared with Example 3, the acetone purity was 99.78%, the methanol content was 500 ppm, and other conditions were consistent with Example 3. The final acetone conversion rate was 28.73%, and the selectivity of acetone to methyl isoheptyl ketone was 87.82%.

[0077] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for preparing multi-carbon methyl ketone from acetone, characterized in that: Under the action of a catalyst, acetone reacts with itself or with the corresponding aldehyde to obtain a multi-carbon methyl ketone of the following formula: Where n = 1-6; The methanol content in the acetone is less than or equal to 250 ppm, preferably less than or equal to 200 ppm, and more preferably less than 100 ppm.

2. The method according to claim 1, characterized in that When n=1, that is, the product is methyl isobutyl ketone, the raw materials are acetone and hydrogen, and the reaction is shown in Formula 1: When n=2, that is, the product is methyl isoamyl ketone, the raw materials are acetone and isobutyraldehyde, and the reaction is shown in Formula 2: When n=3-6, that is, the product is the corresponding multi-carbon methyl ketone, the raw materials are acetone and the corresponding aldehyde, and the reaction is shown in Formula 3:

3. The method according to claim 1 or 2, characterized in that: The catalyst is a metal-support bifunctional catalyst, wherein the metal is at least one of Pd, Pt, Ru, Rh, Ir, Os, preferably at least one of Pd, Pt and Ru; the support is a support containing acidic sites, such as acidic resins (such as sulfonic acid resins, phosphoric acid resins, etc.), acidic oxides (such as alumina, etc.), molecular sieves (such as Hβ molecular sieves, HZSM-5 molecular sieves, etc.), activated carbon, solid superacids (such as fluorosulfonic acid resins, etc.), clays, heteropolyacids (such as phosphotungstic heteropolyacids, etc.), diatomaceous earth, and kaolin.

4. The method according to claim 3, characterized in that: Based on the total mass of the catalyst, the content of metal active components in the catalyst is 0.1wt%-2wt%, and the content of the carrier is 98wt%-99.9wt%.

5. The method according to any one of claims 1 to 4, characterized in that: The reaction temperature is 70°C-250°C, preferably 90°C-200°C; the reaction pressure is 0.5MPa-5MPa, preferably 2MPa-5MPa; the space velocity of the reaction raw materials is 0.1h -1 -5h -1 , preferably 0.5h -1 -3h -1 ; The hydrogen-to-oil ratio is 0.1-5, preferably 0.5-3; wherein, when n=2-6, the reaction raw materials are acetone and polycarbon aldehydes, and the molar ratio of acetone to polycarbon aldehydes is 1.01-3.

6. The method according to any one of claims 1 to 5, characterized in that: The reaction liquid first passes through a light component removal tower to remove light components generated during the reaction, and then passes through an acetone recovery tower to recover unreacted acetone.

7. The method according to claim 6, characterized in that The lightness removal tower is operated under an absolute pressure of 50-500 KPa, preferably 100-200 KPa; the theoretical number of plates is 10-60 plates, preferably 20-50 plates; the feed position is the 5th to 40th plate, preferably the 10th to 30th plate; the reflux ratio is 1-20, preferably 3-15; the tower top temperature is 10°C-150°C, and the tower bottom temperature is 30°C-150°C.

8. The method according to claim 6, characterized in that The acetone recovery tower is operated under an absolute pressure of 30-200 KPa, preferably 50-100 KPa; the theoretical plate number is 20-60 plates, preferably 30-50 plates; the feed position is the 8th to 40th plate, preferably the 10th to 30th plate; the reflux ratio is 0.1-5, preferably 0.5-2; the tower top temperature is 10°C-90°C, and the tower bottom temperature is 30°C-250°C.

9. A selective method for preparing a polycarbon methyl ketone, wherein acetone is reacted with itself or with a corresponding aldehyde in the presence of a catalyst to obtain a polycarbon methyl ketone of the following formula: Where n = 1-6; in, By adjusting the content of methanol in acetone, the selectivity of acetone to multi-carbon methyl ketones and the content of methanol in acetone conform to the following formula: Where S is the selectivity of acetone to multi-carbon methyl ketone, unit % a is the content of methanol in acetone, unit PPm, a≤250, preferably a≤200 x is the acetone conversion rate, unit is %, 10≤x≤80, preferably 30≤x≤80.

10. The method according to claim 9, wherein: The catalyst is a metal-support bifunctional catalyst, wherein the metal is at least one of Pd, Pt, Ru, Rh, Ir, and Os, preferably at least one of Pd, Pt, and Ru; the support is a support containing an acidic site, such as an acidic resin (such as a sulfonic acid resin, a phosphoric acid resin, etc.), an acidic oxide (such as alumina, etc.), a molecular sieve (such as an Hβ molecular sieve, an HZSM-5 molecular sieve, etc.), activated carbon, a solid superacid (such as a fluorosulfonic acid resin, etc.), clay, a heteropolyacid (such as a phosphotungstic heteropolyacid, etc.), diatomaceous earth, and kaolin; Based on the total mass of the catalyst, the content of metal active components in the catalyst is 0.1wt%-2wt%, and the content of the carrier is 98wt%-99.9wt%.

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