Preparation method of 2, 2-dimethoxypropane
Through the method of elimination of molecular sieve catalysts and addition reaction with acid catalysts, the problems of acetone consumption and entrainment loss in 2,2-dimethoxypropane production are solved, and the preparation of high-purity products and energy consumption are reduced.
Patent Information
- Application Number
- CN202411332284.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2024-12-27
AI Technical Summary
In the current production process of 2,2-dimethoxypropane, a large amount of acetone is used to remove excessive energy consumption of methanol, and there are problems of acetone loss and 2,2-dimethoxypropane entrainment loss.
Molecular sieve catalyst is used to eliminate azeotrope of 2,2-dimethoxypropane and methanol, and then the addition reaction is carried out under an acidic catalyst to reduce the use of acetone and side reactions, and obtain high-purity 2,2 by distillation. -Dimethoxypropane.
Reduces energy consumption, reduces acetone loss and entrainment loss of 2,2-dimethoxypropane, improves product purity and catalyst life, and simplifies post-treatment separation operations.
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Abstract
Description
Technical Field
[0001] The invention relates to a method for preparing 2,2-dimethoxypropane. Background Art
[0002] 2,2-Dimethoxypropane is an important fine chemical and a key intermediate for the synthesis of linalool series flavors and fragrances, vitamins A and E, and other pharmaceutical chemicals. It is often used as a protective agent, condensation agent, and dehydrating agent in organic synthesis.
[0003] The main synthesis method of 2,2-dimethoxypropane is the direct synthesis method of acetone and methanol. Acidic catalysts are used. The reaction system is in equilibrium. The conversion rate depends on the reaction temperature and the ratio of raw materials. The azeotropic ratio of methanol and 2,2-dimethoxypropane is 45 / 50. To obtain pure 2,2-dimethoxypropane, a large amount of acetone needs to be used for azeotropic distillation to remove methanol, which consumes a lot of energy and will also cause entrainment loss of 2,2-dimethoxypropane.
[0004] U.S. Patent No. 4775447 discloses a method for preparing pure 2,2-dimethoxypropane, wherein an acidic resin catalyst is used at 0-25°C to obtain a mixture of methanol, acetone and 2,2-dimethoxypropane, and most of the methanol is removed azeotropically by adding acetone, resulting in large acetone material loss, high energy consumption for azeotropic distillation, and low single-pass efficiency.
[0005] CN109206304B discloses a method for preparing pure 2,2-dimethoxypropane, which uses a reaction distillation method to obtain a crude mixture of methanol, acetone and 2,2-dimethoxypropane. Methanol is removed by membrane separation, and then acetone and 2,2-dimethoxypropane are separated by distillation to obtain 2,2-dimethoxypropane with a purity of 98.5%. This method has high separation energy consumption and large investment in membrane separation equipment.
[0006] CN109438196A discloses a method for preparing 2,2-dimethoxypropane by azeotropic condensation of multiple towers in series, wherein the reaction pressure is controlled at 700Pa-2000Pa, the reaction temperature of the tower bottom is between 2-18°C, the azeotropic product is collected at the top of the tower, and 2-5 plate distillation towers are used in series for separation to obtain 2,2-dimethoxypropane with a purity of more than 98%. The operating parameters of this method are difficult to control, and the equipment investment is large. Summary of the invention
[0007] In order to solve the problems of excessive energy consumption, unit consumption of acetone and entrainment loss of 2,2-dimethoxypropane in the production process of 2,2-dimethoxypropane in the prior art, the present invention provides a method for preparing 2,2-dimethoxypropane, which avoids unnecessary acetone consumption and entrainment loss of 2,2-dimethoxypropane and obtains high-purity 2,2-dimethoxypropane.
[0008] The present invention solves the above technical problems through the following technical solutions.
[0009] The present invention provides a method for preparing 2,2-dimethoxypropane, which comprises the following steps:
[0010] S1: Under the action of a molecular sieve catalyst, an azeotrope of 2,2-dimethoxypropane and methanol undergoes an elimination reaction to obtain an azeotrope of 2-methoxypropylene and methanol;
[0011] ;
[0012] S2: Under the action of an acidic catalyst, the azeotrope of 2-methoxypropylene and methanol undergoes an addition reaction with methanol to obtain 2,2-dimethoxypropane;
[0013] .
[0014] In step S1, the molecular sieve catalyst may be a conventional molecular sieve catalyst for such reactions in the art. Preferably, the molecular sieve catalyst is a modified molecular sieve catalyst, such as an acid-modified ZSM molecular sieve catalyst.
[0015] In one embodiment, in step S1, the mass percentage of 2,2-dimethoxypropane in the azeotrope of 2,2-dimethoxypropane and methanol is 40-70%, for example, 55%.
[0016] In one embodiment, in step S1, the azeotrope of 2,2-dimethoxypropane and methanol is prepared by the following steps:
[0017] S0: Under the catalysis of cationic acid resin, methanol and acetone undergo condensation reaction to obtain the azeotrope of 2,2-dimethoxypropane and methanol.
[0018] In step S0, the cationic acid resin may be a conventional cationic acid resin column for such reactions in the art, for example, a 732 cationic resin column.
[0019] The volume of the 732 cationic resin column may be 800-1500 mL, for example, 1000 mL.
[0020] In step S0, the molar ratio of methanol to acetone can be a conventional molar ratio for such reactions in the art, preferably (2-5):1, for example, 4:1, 3:1, 2.5:1, 5:1 or 2.8:1.
[0021] In one embodiment, in step S0, methanol and acetone are mixed and passed into a cationic acid resin column, and the flow rate of the mixture of methanol and acetone is 10-60 ml / min, for example, 50, 25, 30, 20 or 16.7 ml / min.
[0022] In step S0, the temperature of the condensation reaction can be a conventional temperature for such reactions in the art. Preferably, the temperature of the condensation reaction is -60--20°C, for example -60, -50, -40, -20 or -30°C.
[0023] In step S0, the progress of the condensation reaction can be monitored by conventional detection methods in the art (such as TLC, HPLC or GC). Generally, the completion of the acetone reaction is regarded as the end point of the reaction. Preferably, the reaction time of the condensation reaction is 15-60 min, such as 60, 50, 35, 40 or 20 min.
[0024] In step S0, after the condensation reaction is completed, the following post-processing steps may also be included:
[0025] (S0-1) removing the azeotrope of methanol and acetone by atmospheric distillation;
[0026] (S0-2) is further distilled at atmospheric pressure to obtain an azeotropic mixture of 2,2-methoxypropylene and methanol.
[0027] In one embodiment, in step (S0-1), the top temperature of the distillation is 55-56°C.
[0028] In one embodiment, in step (S0-2), the top temperature of the distillation is 59-61°C.
[0029] In one embodiment, in steps (S0-1) and (S0-2), the distillation is performed in a distillation column with a height of 1-1.5 m, for example, 1 m.
[0030] In one embodiment, in step S1, the elimination reaction is carried out in a solid bed, preferably, in a fixed bed filled with the molecular sieve catalyst, and the volume of the solid bed is 400-1000 mL, for example, 500 mL.
[0031] In one embodiment, in step S1, the flow rate of the azeotrope of 2,2-dimethoxypropane and methanol is 0.5-4 ml / min, for example, 1.8, 1.2, 1.1, 0.9 or 3.6 ml / min.
[0032] In step S1, the reaction temperature of the elimination reaction can be a conventional temperature for such reactions in the art. Preferably, the reaction temperature of the elimination reaction is 220-300°C.
[0033] In one embodiment, the reaction temperature of the elimination reaction is 260-265°C, 280-285°C, 240-245°C, 220-225°C or 295-300°C.
[0034] In step S1, the progress of the elimination reaction can be monitored by conventional detection methods in the art (such as TLC, HPLC or GC). Generally, the disappearance of 2,2-dimethoxypropane is taken as the end point of the reaction. Preferably, the reaction time of the elimination reaction is 30-120 s, for example, 30, 60, 90, 100 or 120 s.
[0035] In step S1, after the elimination reaction is completed, the following post-treatment step may be further included: obtaining an azeotrope of 2-methoxypropylene and methanol by atmospheric distillation.
[0036] In one embodiment, the top temperature of the atmospheric distillation is 31-33°C.
[0037] In step S2, the acidic catalyst may be a conventional acidic catalyst for such reactions in the art, such as one or more of phosphoric acids and their esters, sulfonic acids and their esters, ammonium halides, strong acid ammonium salts and organic carboxylic acids; preferably phosphoric acid, phosphorous acid, methanesulfonic acid, ammonium chloride or nonanoic acid.
[0038] In step S2, the amount of the acidic catalyst added can be the conventional amount used in this type of reaction in the art. Preferably, the mass ratio of the acidic catalyst to 2-methoxypropylene is (0.02-0.1):100, for example, 0.034:100 or 0.068:100.
[0039] In step S2, in the addition reaction, based on total methanol, the molar ratio of methanol to 2-methoxypropylene is (0.93-0.99):1, for example, 0.98, 0.97 or 0.95, wherein the total methanol includes the sum of the added methanol and the "methanol in the azeotrope of 2-methoxypropylene and methanol".
[0040] In one embodiment, in step S2, the mass percentage of 2-methoxypropylene in the azeotrope of 2-methoxypropylene and methanol is 90-98%, for example, 95%.
[0041] In one embodiment, in step S2, the addition reaction is carried out in an autoclave, and the volume of the autoclave is 800-1200 mL, for example, 1000 mL.
[0042] In step S2, the reaction temperature of the addition reaction can be a conventional temperature for such reactions in the art. Preferably, the reaction temperature of the addition reaction is 10-80°C, for example, 30-35°C, 45-50°C, 40-45°C or 70-80°C.
[0043] In step S2, the progress of the addition reaction can be monitored by conventional detection methods in the art (such as TLC, HPLC or GC). Generally, the end point of the reaction is when the added methanol is completely converted. Preferably, the reaction time of the addition reaction is 0.5-6h, for example, 1h or 2h.
[0044] In step S2, after the addition reaction is completed, the following post-processing steps may also be included:
[0045] (S2-1): cooling the obtained material and distilling it under normal pressure to recover 2-methoxypropylene;
[0046] (S2-2): Continue distillation under normal pressure to obtain 2,2-dimethoxypropane.
[0047] In one embodiment, the cooling temperature in the step (S2-1) is 25-35°C, for example, 30°C.
[0048] The top temperature of the atmospheric distillation in the step (S2-1) is 33-34°C, for example, 33°C.
[0049] The top temperature of the atmospheric distillation in the step (S2-2) is 82-83°C, for example 83°C.
[0050] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.
[0051] The reagents and raw materials used in the present invention are commercially available.
[0052] The positive and progressive effects of the present invention are:
[0053] (1) There is no need to add a large amount of acetone. The azeotropic separation system has residual methanol. Only the azeotropic product of methanol and 2,2-dimethoxypropane is collected. The acetone loss is small, the 2,2-dimethoxypropane distillation entrainment loss is small, and the energy consumption is low. (2) The azeotropic product of methanol and 2,2-dimethoxypropane is used for the elimination reaction. Methanol plays the role of a diluent and a protective agent. There are few side reactions such as polymerization and coking on the catalyst surface, and the catalyst life is long. (3) 2,2-dimethoxypropane is prepared using 2-methoxypropylene and methanol under acid catalyst. There is almost no side reaction. Only a small amount of raw material 2-methoxypropylene needs to be distilled to remove. The post-treatment separation and purification operation is simple, the energy consumption is low, and the obtained 2,2-dimethoxypropane is of high purity. DETAILED DESCRIPTION
[0054] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.
[0055] The catalyst information used in the following examples is as follows:
[0056] Modified ZSM molecular sieve catalyst: Add 500g of silica-alumina molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., ZSM-5) into 1L of 1% phosphoric acid aqueous solution (prepared with 85% phosphoric acid and purified water), soak at room temperature for 2h, filter out the soaking liquid, dry the obtained molecular sieve at 60℃ for 10h, and then calcine the obtained molecular sieve at 300℃ for 3h.
[0057] Example 1
[0058] Prepare a mixture of 1000g methanol and 453g acetone, with a molar ratio of methanol to acetone of 4, and pass it into a 732 cationic resin column pre-cooled to -60°C, with a resin column volume of 1000mL, a flow rate controlled at 50ml / min, a residence time controlled at 20min, and the material at the outlet of the resin column is neutralized with sodium bicarbonate and then transferred to a 1m high distillation column. First, perform atmospheric distillation, with the top temperature controlled at 55-56°C, and distill to remove 240g of methanol and acetone azeotrope (acetone content 88%), and then perform atmospheric distillation, with the top temperature controlled at 59-61°C, to obtain 782g of methanol and 2,2-dimethoxypropane azeotrope, and the gas phase detection shows that the 2,2-dimethoxypropane content is 55%, and the methanol content is 45%.
[0059] The above 2,2-dimethoxypropane azeotrope was pumped into a high-temperature fixed bed filled with a modified ZSM molecular sieve catalyst at a flow rate of 1.8 ml / min, the fixed bed volume was 500 mL, the fixed bed was preheated to 280-285°C, and the residence time was controlled at about 60 seconds. The outlet material was collected, and the gas phase showed that the conversion rate of 2,2-dimethoxypropane was 99%. Through atmospheric distillation, the top temperature was controlled at 31-33°C to obtain 310 g of 2-methoxypropylene and methanol azeotrope, wherein the 2-methoxypropylene content was 95% and the methanol content was 5%.
[0060] The 95% 2-methoxypropylene was transferred into a 1L autoclave, 113g methanol was added, the total amount of methanol (the sum of the additional methanol and the methanol contained in 2-methoxypropylene) accounted for 0.98 equivalents, and 0.1g 85% phosphoric acid was added as a catalyst. The temperature was raised to between 30-35°C and the reaction was carried out for 1h. The material was cooled to 30°C and transferred out. The methanol conversion rate was 100% by gas phase detection. The atmospheric distillation was carried out with the top temperature controlled at 33°C. 2-methoxypropylene was recovered and atmospheric distillation was continued until the top temperature reached 83°C. The system was collected until it was completely evaporated to dryness. 415g of 2,2-dimethoxypropane was obtained. The purity of the gas phase detection was 99.7%, the single-step yield was 99.3%, and the total yield of the three steps (based on acetone) was 48.3%.
[0061] Example 2
[0062] Prepare a mixture of 1000g methanol and 598g acetone, with a molar ratio of 3 between methanol and acetone, and pass it into a 732 cationic resin column pre-cooled to -40°C, with a resin column volume of 1000mL, a flow rate controlled at 25ml / min, a residence time controlled at 40min, and the material at the outlet of the resin column is neutralized with sodium bicarbonate and then transferred to a 1m high distillation column. First, perform atmospheric distillation, with the top temperature controlled at 55-56°C, and distill to remove 318g of methanol and acetone azeotrope (acetone / content 88%), and then perform atmospheric distillation, with the top temperature controlled at 59-61°C, to obtain 1043g of methanol and 2,2-dimethoxypropane azeotrope, and the gas phase detection shows that the 2,2-dimethoxypropane content is 55%, and the methanol content is 45%.
[0063] The above 2,2-dimethoxypropane azeotrope was pumped into a high-temperature fixed bed filled with a modified ZSM molecular sieve catalyst at a flow rate of 1.2 ml / min, the fixed bed volume was 500 mL, the fixed bed was preheated to 260-265°C, and the residence time was controlled at about 90 seconds. The outlet material was collected, and the gas phase showed that the conversion rate of 2,2-dimethoxypropane was 98.5%. Through atmospheric distillation, the top temperature was controlled at 31-33°C to obtain 412 g of 2-methoxypropylene and methanol azeotrope, wherein the 2-methoxypropylene content was 95% and the methanol content was 5%.
[0064] The 95% 2-methoxypropylene was transferred into a 1L autoclave, 148g methanol was added, the total amount of methanol (the sum of the additional methanol and the methanol contained in 2-methoxypropylene) accounted for 0.97 equivalents, and 0.2g phosphorous acid was added as a catalyst. The temperature was raised to 45-50°C and the reaction was carried out for 2h. The material was cooled to 30°C and transferred out. The methanol conversion rate was 100% by gas phase detection. The atmospheric distillation was carried out with the top temperature controlled at 33°C. 2-methoxypropylene was recovered and atmospheric distillation was continued until the top temperature reached 83°C. The system was collected until it was completely evaporated to dryness. 540g of 2,2-dimethoxypropane was obtained. The purity of the gas phase detection was 99.8%, the single-step yield was 99.4%, and the total yield of the three steps (based on acetone) was 48.1%.
[0065] Example 3
[0066] Prepare a mixture of 1000g methanol and 598g acetone, with a molar ratio of methanol to acetone of 2.5, and pass it into a 732 cationic resin column pre-cooled to -50°C, with a resin column volume of 1000mL, a flow rate controlled at 30ml / min, a residence time controlled at 35min, and the material at the outlet of the resin column is neutralized with sodium bicarbonate and then transferred to a 1m high distillation column. First, perform atmospheric distillation, with the top temperature controlled at 55-56°C, and distill to remove 410g of methanol and acetone azeotrope (acetone content 88%), and then perform atmospheric distillation, with the top temperature controlled at 59-61°C, to obtain 1181g of methanol and 2,2-dimethoxypropane azeotrope, and the gas phase detection shows that the 2,2-dimethoxypropane content is 55% and the methanol content is 45%.
[0067] The above 2,2-dimethoxypropane azeotrope was pumped into a high-temperature fixed bed filled with a modified ZSM molecular sieve catalyst at a flow rate of 1.1 ml / min, the fixed bed volume was 500 mL, the fixed bed was preheated to 240-245°C, and the residence time was controlled at about 100 s. The outlet material was collected, and the gas phase showed that the conversion rate of 2,2-dimethoxypropane was 98.0%. Through atmospheric distillation, the top temperature was controlled at 31-33°C to obtain 458 g of 2-methoxypropylene and methanol azeotrope, wherein the 2-methoxypropylene content was 95% and the methanol content was 5%.
[0068] The 95% 2-methoxypropylene was transferred into a 1L autoclave, and 161g of methanol was added. The total amount of methanol (the sum of the additional methanol and the methanol contained in 2-methoxypropylene) accounted for 0.95 equivalents. 0.1g of methanesulfonic acid was added as a catalyst. The temperature was raised to 40-45°C and the reaction was carried out for 1h. The material was cooled to 30°C and transferred out. The methanol conversion rate was 100% by gas phase detection. The atmospheric distillation was carried out with the top temperature controlled at 33°C. 2-methoxypropylene was recovered and atmospheric distillation was continued until the top temperature reached 83°C. The system was collected until it was completely evaporated to dryness. 593g of 2,2-dimethoxypropane was obtained. The purity of the gas phase detection was 99.7%, the single-step yield was 99.0%, and the total yield of the three steps (based on acetone) was 48.2%.
[0069] Example 4
[0070] Prepare a mixture of 1000g methanol and 363g acetone, with a molar ratio of 5 between methanol and acetone, and pass it into a 732 cationic resin column pre-cooled to -20°C, with a resin column volume of 1000mL, a flow rate controlled at 20ml / min, a residence time controlled at 50min, and the material at the outlet of the resin column is neutralized with sodium bicarbonate and then transferred to a 1m high distillation column. First, perform atmospheric distillation, with the top temperature controlled at 55-56°C, and distill to remove 410g of methanol and acetone azeotrope (acetone / content 88%), then perform atmospheric distillation, with the top temperature controlled at 59-61°C, to obtain 626g of methanol and 2,2-dimethoxypropane azeotrope, and the gas phase detection shows that the 2,2-dimethoxypropane content is 55% and the methanol content is 45%.
[0071] The above 2,2-dimethoxypropane azeotrope was pumped into a high-temperature fixed bed filled with a modified ZSM molecular sieve catalyst at a flow rate controlled at 0.9 ml / min. The fixed bed volume was 500 mL. The fixed bed was preheated to 220-225°C and the residence time was controlled at about 120 s. The outlet material was collected, and the gas phase showed that the conversion rate of 2,2-dimethoxypropane was 99.0%. Through atmospheric distillation, the top temperature was controlled at 31-33°C to obtain 248 g of 2-methoxypropylene and methanol azeotrope, wherein the 2-methoxypropylene content was 95% and the methanol content was 5%.
[0072] The 95% 2-methoxypropylene was transferred into a 1L autoclave, 90g methanol was added, the total amount of methanol (the sum of the additional methanol and the methanol contained in 2-methoxypropylene) accounted for 0.98 equivalents, and 0.2g ammonium chloride was added as a catalyst. The temperature was raised to 70-80°C, and the reaction was carried out for 1h. The material was cooled to 30°C and transferred out. The methanol conversion rate was 100% by gas phase detection. Atmospheric distillation was performed, and the top temperature was controlled at 33°C. 2-methoxypropylene was recovered, and atmospheric distillation was continued until the top temperature reached 83°C. The system was collected until it was completely evaporated to dryness, and 325g of 2,2-dimethoxypropane was obtained. The purity of the gas phase detection was 99.3%, the single-step yield was 97.2%, and the total yield of the three steps (based on acetone) was 47.7%.
[0073] Example 5
[0074] Prepare a mixture of 1000g methanol and 634g acetone, with a molar ratio of methanol to acetone of 2.8, and pass it into a 732 cationic resin column pre-cooled to -30°C, with a resin column volume of 1000mL, a flow rate controlled at 16.7ml / min, a residence time controlled at 60min, and the material at the outlet of the resin column is neutralized with sodium bicarbonate and then transferred to a 1m high distillation column. First, perform atmospheric distillation, with the top temperature controlled at 55-56°C, and distill to remove 410g of methanol and acetone azeotrope (acetone content 88%), and then perform atmospheric distillation, with the top temperature controlled at 59-61°C, to obtain 1095g of methanol and 2,2-dimethoxypropane azeotrope, and the gas phase detection shows that the 2,2-dimethoxypropane content is 55%, and the methanol content is 45%.
[0075] The above 2,2-dimethoxypropane azeotrope was pumped into a high-temperature fixed bed filled with a modified ZSM molecular sieve catalyst at a flow rate of 3.6 ml / min, the fixed bed volume was 500 mL, the fixed bed was preheated to 295-300°C, and the residence time was controlled at about 30 seconds. The outlet material was collected, and the gas phase showed that the conversion rate of 2,2-dimethoxypropane was 98.0%. Through atmospheric distillation, the top temperature was controlled at 31-33°C to obtain 430 g of 2-methoxypropylene and methanol azeotrope, wherein the 2-methoxypropylene content was 95% and the methanol content was 5%.
[0076] The 95% 2-methoxypropylene was transferred into a 1L autoclave, and 155g of methanol was added. The total amount of methanol (the sum of the additional methanol and the methanol contained in 2-methoxypropylene) accounted for 0.98 equivalents. 0.2g of nonanoic acid was added as a catalyst. The temperature was raised to 70-80°C and the reaction was carried out for 1h. The material was cooled to 30°C and transferred out. The methanol conversion rate was 100% by gas phase detection. The atmospheric distillation was carried out with the top temperature controlled at 33°C. 2-methoxypropylene was recovered and atmospheric distillation was continued until the top temperature reached 83°C. The system was collected until it was completely evaporated to dryness. 570g of 2,2-dimethoxypropane was obtained. The purity of the gas phase detection was 99.3%, the single-step yield was 98.3%, and the total yield of the three steps (based on acetone) was 47.3%.
[0077] Comparative Example 1
[0078] Prepare a mixture of 1000g methanol and 453g acetone, with a molar ratio of methanol to acetone of 4, and pass it into a 732 cationic resin column pre-cooled to -60°C. The volume of the resin column is 1000mL, the flow rate is controlled at 50ml / min, and the residence time is controlled at 20min. After the material at the outlet of the resin column is neutralized with sodium bicarbonate, it is transferred to a 1m high distillation column. Add 5200g acetone, first perform atmospheric distillation, control the top temperature at 55-56°C, distill to remove 6200g of methanol and acetone azeotrope (acetone content 88%, containing 1.2% 2,2-dimethoxypropane), continue atmospheric distillation until the top temperature reaches 83°C, start collecting until the system is completely evaporated to dryness, and obtain 355g of 2,2-dimethoxypropane, with a gas phase detection purity of 98.3% and a yield (based on acetone) of 43.7%.
[0079] Comparative Example 2
[0080] Prepare a mixture of 1000g methanol and 598g acetone, with a molar ratio of 3 between methanol and acetone, and pass it into a 732 cationic resin column pre-cooled to -40°C. The volume of the resin column is 1000mL, the flow rate is controlled at 25ml / min, and the residence time is controlled at 40min. After the material at the outlet of the resin column is neutralized with sodium bicarbonate, it is transferred to a 1m high distillation column. Add 4500g acetone, first perform atmospheric distillation, control the top temperature at 55-56°C, distill to remove 5500g of methanol and acetone azeotrope (acetone content 88%, containing 2.0% 2,2-dimethoxypropane), continue atmospheric distillation until the top temperature reaches 83°C, start collecting until the system is completely evaporated to dryness, and obtain 460g of 2,2-dimethoxypropane, with a gas phase detection purity of 98.1% and a yield (based on acetone) of 42.4%.
Claims
1. A method for preparing 2,2-dimethoxypropane, characterized in that: It includes the following steps: S1: Under the action of a molecular sieve catalyst, an azeotrope of 2,2-dimethoxypropane and methanol undergoes an elimination reaction to obtain an azeotrope of 2-methoxypropylene and methanol; ； S2: Under the action of an acidic catalyst, the azeotrope of 2-methoxypropylene and methanol undergoes an addition reaction with methanol to obtain 2,2-dimethoxypropane; 。 2. The method for preparing 2,2-dimethoxypropane according to claim 1, characterized in that: It meets one or more of the following conditions: (1) In step S1, the molecular sieve catalyst is a modified molecular sieve catalyst; (2) In step S1, the mass percentage of 2,2-dimethoxypropane in the azeotrope of 2,2-dimethoxypropane and methanol is 40-70%; (3) In step S1, the elimination reaction is carried out in a solid bed; (4) In step S1, the flow rate of the azeotrope of 2,2-dimethoxypropane and methanol is 0.5-4 ml / min; (5) In step S1, the reaction temperature of the elimination reaction is 220-300°C; (6) In step S1, the reaction time of the elimination reaction is 30-120 s; and (7) In step S1, after the elimination reaction is completed, the following post-treatment step is also included, in which an azeotrope of 2-methoxypropylene and methanol is obtained by atmospheric distillation.
3. The method for preparing 2,2-dimethoxypropane according to claim 2, characterized in that: It meets one or more of the following conditions: (1) In step S1, the molecular sieve catalyst is an acid-modified ZSM molecular sieve catalyst; (2) In step S1, the mass percentage of 2,2-dimethoxypropane in the azeotrope of 2,2-dimethoxypropane and methanol is 55%; (3) In step S1, the elimination reaction is carried out in a fixed bed filled with the molecular sieve catalyst, and the volume of the solid bed is 400-1000 mL, for example, 500 mL; (4) In step S1, the flow rate of the azeotrope of 2,2-dimethoxypropane and methanol is 1.8, 1.2, 1.1, 0.9 or 3.6 ml / min; (5) The reaction temperature of the elimination reaction is 260-265°C, 280-285°C, 240-245°C, 220-225°C or 295-300°C; (6) In step S1, the reaction time of the elimination reaction is 30, 60, 90, 100 or 120 seconds; and (7) The top temperature of the atmospheric distillation is 31-33°C.
4. The method for preparing 2,2-dimethoxypropane according to claim 1, characterized in that: In step S1, the azeotrope of 2,2-dimethoxypropane and methanol is prepared by the following steps: S0: Under the catalysis of cationic acid resin, methanol and acetone undergo condensation reaction to obtain the azeotrope of 2,2-dimethoxypropane and methanol.
5. The method for preparing 2,2-dimethoxypropane according to claim 4, characterized in that: It meets one or more of the following conditions: (1) In step S0, the cationic acid resin is a 732 cationic resin column; (2) In step S0, the molar ratio of methanol to acetone is (2-5):1; (3) In step S0, methanol and acetone are mixed and passed into a cationic acid resin column, and the flow rate of the mixture of methanol and acetone is 10-60 ml / min; (4) In step S0, the temperature of the condensation reaction is -60 to 20°C; (5) In step S0, the reaction time of the condensation reaction is 15-60 min; and (6) In step S0, after the condensation reaction is completed, the following post-treatment steps are also included: (S0-1) removing the azeotrope of methanol and acetone by atmospheric distillation; (S0-2) is further distilled at atmospheric pressure to obtain an azeotropic mixture of 2,2-methoxypropylene and methanol.
6. The method for preparing 2,2-dimethoxypropane according to claim 5, characterized in that: It meets one or more of the following conditions: (1) The volume of the 732 cationic resin column is 800-1500 mL, for example, 1000 mL; (2) In step S0, the molar ratio of methanol to acetone is 4:1, 3:1, 2.5:1, 5:1 or 2.8:1; (3) In step S0, methanol and acetone are mixed and passed into a cationic acid resin column, and the flow rate of the mixture of methanol and acetone is 50, 25, 30, 20 or 16.7 ml / min; (4) In step S0, the temperature of the condensation reaction is -60, -50, -40, -20 or -30°C; (5) In step S0, the reaction time of the condensation reaction is 60, 50, 35, 40 or 20 min; (6) In step (S0-1), the top temperature of the atmospheric distillation is 55-56°C; (7) In step (S0-2), the top temperature of the atmospheric distillation is 59-61°C; and (8) In steps (S0-1) and (S0-2), the atmospheric distillation is carried out in a distillation column with a height of 1-1.5 m, for example, 1 m.
7. The method for preparing 2,2-dimethoxypropane according to claim 1, characterized in that: It meets one or more of the following conditions: (1) In step S2, the acidic catalyst is one or more of phosphoric acid and its esters, sulfonic acid and its esters, ammonium halides, strong acid ammonium salts and organic carboxylic acids; (2) In step S2, the mass ratio of the acidic catalyst to 2-methoxypropylene is (0.02-0.1):100; (3) In step S2, in the addition reaction, the molar ratio of methanol to 2-methoxypropylene, calculated on the basis of total methanol, is (0.93-0.99):1, wherein the total methanol includes the sum of the added methanol and "methanol in the azeotrope of 2-methoxypropylene and methanol"; (4) In step S2, the mass percentage of 2-methoxypropylene in the azeotrope of 2-methoxypropylene and methanol is 90-98%; (5) In step S2, the addition reaction is carried out in an autoclave, and the volume of the autoclave is 800-1200 mL; (6) In step S2, the reaction temperature of the addition reaction is 10-80°C; and (7) In step S2, the reaction time of the addition reaction is 0.5-6h.
8. The method for preparing 2,2-dimethoxypropane according to claim 1, characterized in that: It meets one or more of the following conditions: (1) In step S2, the acidic catalyst is phosphoric acid, phosphorous acid, methanesulfonic acid, ammonium chloride or nonanoic acid; (2) In step S2, the mass ratio of the acidic catalyst to 2-methoxypropylene is 0.034:100 or 0.068:100; (3) In step S2, in the addition reaction, the molar ratio of methanol to 2-methoxypropylene is 0.98, 0.97 or 0.95 based on the total methanol, wherein the total methanol includes the sum of the added methanol and the methanol in the azeotrope of 2-methoxypropylene and methanol; (4) In step S2, the mass percentage of 2-methoxypropylene in the azeotrope of 2-methoxypropylene and methanol is 95%; (5) In step S2, the addition reaction is carried out in an autoclave, and the volume of the autoclave is 1000 mL; (6) In step S2, the reaction temperature of the addition reaction is 30-35°C, 45-50°C, 40-45°C or 70-80°C; and (7) In step S2, the reaction time of the addition reaction is 1 h or 2 h.
9. The method for preparing 2,2-dimethoxypropane according to claim 1, characterized in that: In step S2, after the addition reaction is completed, the following post-processing steps may also be included: (S2-1): cooling the obtained material and distilling it under normal pressure to recover 2-methoxypropylene; (S2-2): Continue distillation under normal pressure to obtain 2,2-dimethoxypropane.
10. The method for preparing 2,2-dimethoxypropane according to claim 9, characterized in that: It meets one or more of the following conditions: (1) In step (S2-1), the cooling temperature is 25-35°C, for example, 30°C; (2) the top temperature of the atmospheric distillation in step (S2-1) is 33-34°C, for example, 33°C; and (3) The top temperature of the atmospheric distillation in step (S2-2) is 82-83°C, for example, 83°C.