Method for catalytically synthesizing 1, 2-diol by using titanium silicalite molecular sieve

Abstract

The invention is suitable for the technical field of fine chemical engineering, and provides a method for catalytically synthesizing 1, 2-diol by using a titanium silicalite molecular sieve, which comprises the following steps: preparing methanol, a hydrogen peroxide solution and an alkaline additive into a homogeneous mixed solution, mixing the homogeneous mixed solution with a raw material olefin in a mixing tank, pumping into a fixed bed reactor, and carrying out a titanium silicalite molecular sieve catalytic epoxidation reaction to obtain 1, 2-diol. A 1, 2-alkylene oxide solution is generated; the method comprises the following steps: separating a 1, 2-alkylene oxide solution, recycling a substrate olefin and a solvent methanol, and carrying out hydration reaction on 1, 2-alkylene oxide and water in a fixed bed reactor under the action of an ion exchange resin catalyst to generate 1, 2-diol; and feeding the hydration product into a rectifying tower, and carrying out dehydration and impurity removal to obtain a high-purity odorless 1, 2-diol product. The method has the advantages of high product yield, no odor, inhibition of impurity generation, improvement of the product quality, simplification of the production process, no environmental pollution and realization of green production.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical industry, and in particular relates to a method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve. Background Art

[0002] 1,2-Diol (1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol) is an important fine chemical product. It is non-corrosive and miscible with a variety of organic compounds. It is mainly used in the cosmetics field as a moisturizing and bactericidal ingredient. It is also widely used in the fields of inks, pharmaceutical intermediates, etc.

[0003] At present, the technical route for the industrial-scale production of 1,2-diol is to use hydrogen peroxide as the oxidant and formic acid as the reaction medium to obtain peroxyformic acid in situ. Olefins (1-pentene, 1-hexene, 1-octene) are oxidized with formic acid to form the intermediate product 1,2-diol formate, and then the 1,2-diol product is obtained through processes such as hydrolysis, neutralization, extraction and distillation.

[0004] The main problems of this technical route are as follows: ① The oxidation reaction is an intermittent kettle reaction, the materials are seriously mixed, the operation process cannot be continuous, there are many side reactions, and the presence of performic acid makes the production safety risk high; ② A large amount of organic acid waste liquid, waste salt, etc. are produced, and the pressure of environmental protection treatment is high; ③ The participation of organic acids in the synthesis process makes the final product difficult to use in high-end cosmetics due to factors such as allergic reactions; ④ The final product has low purity, strong odor and low yield.

[0005] In recent years, researchers have tried to improve product yield and production efficiency by replacing reactors, introducing catalysts, adjusting process flows, etc., but there has still been no qualitative improvement.

[0006] Chinese patent publication number: CN 1465556 A, reports that 1-hexene is used as raw material, under the action of organic acid, peroxide is used as oxidant, and 1,2-hexanediol product is obtained through oxidation, deacidification, hydrolysis, separation and purification. However, the process of this route is complicated, difficult to continuously produce, and the yield is only 75%.

[0007] Chinese patent publication number: CN 107903146 ​​A, the catalyst MVO2dipic was introduced into the hexene epoxidation stage, so that the final 1,2-hexanediol yield reached more than 85%. The introduction of the catalyst only achieved an improvement in yield.

[0008] Chinese patent publication number: CN 103894126 A, invented a microchannel reactor. Although the reactor improves the mass transfer and heat transfer of materials, the catalytic system is still peroxyformic acid, and the hydrolysis is still carried out using sodium hydroxide solution, which cannot fundamentally achieve the greening of the reaction.

[0009] Chinese patent publication number: CN 106316783 A, uses a gas-liquid pipeline to prepare 1,2-hexanediol, with a purity greater than 99% and a yield of up to 88%, but uses dichloromethane as a solvent, which is highly toxic.

[0010] Chinese patent publication number: CN 110272329 A, proposes a synthesis route without the participation of formic acid. No hazardous material peroxyformic acid is formed during the reaction, and the safety risk of production is low; however, its hydrolysis reaction still uses p-toluenesulfonic acid or sodium hydroxide aqueous solution as a catalyst, and neutralization is still required after hydrolysis.

[0011] In summary, the current production of 1,2-diol generally uses organic acids, liquid alkalis and other raw materials, and environmental safety issues, product quality issues and intermittent reaction methods need to be solved urgently. Therefore, it is urgent to develop a method for synthesizing 1,2-diol catalyzed by titanium silicon molecular sieve to overcome the shortcomings in current practical applications. Summary of the invention

[0012] The object of the present invention is to provide a method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve, aiming to solve the problems mentioned in the above background technology.

[0013] The present invention is achieved by a method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve, comprising the following steps:

[0014] Step 1: Olefin epoxidation

[0015] Methanol, hydrogen peroxide solution and alkaline additive are prepared into a homogeneous mixed solution, which is mixed with raw olefin in a mixing tank and then injected into a fixed bed reactor for epoxidation reaction catalyzed by titanium silicon molecular sieve to generate 1,2-epoxyalkane solution;

[0016] Step 2: 1,2-Alkylene Oxide Hydration

[0017] After the 1,2-alkylene oxide solution is separated (i.e., the methanol, olefin, and alkylene oxide mixed solution are separated), the substrate olefin and the solvent methanol are recycled, and the 1,2-alkylene oxide and water react with each other in a fixed bed reactor under the action of an ion exchange resin catalyst to generate 1,2-diol;

[0018] Step 3: Purification of 1,2-diol

[0019] The hydration product is sent to a distillation tower for dehydration and impurity removal to obtain a high-purity, odorless 1,2-diol product.

[0020] According to a further technical solution, in step 1, the alkaline additive is one of ammonia water, alkaline ammonium salt, organic amine or a combination thereof, and the amount of the alkaline additive added is 0-0.01% of the mass of hydrogen peroxide.

[0021] In a further technical solution, in step 1, the raw material olefin is 1-pentene, 1-hexene or 1-octene.

[0022] According to a further technical solution, in step 1, the titanium silicalite catalyst is one or a combination of cylindrical or spherical titanium silicalite molecular sieves having an MFI or MWW topological structure.

[0023] A further technical solution is that in step one, the olefin epoxidation reaction is continuously carried out in a fixed bed reactor, and the feeding method is upper feeding and lower discharging or lower feeding and upper discharging; the reaction temperature is 5-80°C, the pressure is 0-50Bar, the mass space velocity is 0.5-6, the molar ratio of olefin to hydrogen peroxide raw materials is 1.2-2.0:1, and the mass of methanol added is 3-6 times the mass of hydrogen peroxide solution.

[0024] A further technical solution is that in step 1, the reaction temperature is 10-60°C, the mass space velocity is 1-5, the molar ratio of olefin to hydrogen peroxide raw materials is 1.5-2.0:1, and the mass of methanol added is 3-5 times the mass of hydrogen peroxide solution.

[0025] According to a further technical solution, in step 2, the ion exchange resin catalyst is a macroporous acidic ion exchange resin catalyst.

[0026] A further technical solution is that in step 2, the hydration reaction of 1,2-alkylene oxide is continuously carried out in a fixed bed reactor, and the feeding method is upper feeding and lower discharging or lower feeding and upper discharging; water and 1,2-alkylene oxide are introduced into the fixed bed reactor at a molar ratio of 15-30:1, the reaction temperature is 10-80°C, and the mass space velocity is 0.5-6.

[0027] According to a further technical solution, in step 2, the molar ratio of water to 1,2-epoxyalkane is 15-25:1, the hydration reaction temperature is 20-70°C, and the mass space velocity is 1-5.

[0028] The present invention provides a method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve, which has the following beneficial effects:

[0029] 1) The product yield of 1,2-diol is greater than 92%, and it is odorless. The introduction of alkaline additives further improves the selectivity of the epoxidation reaction, inhibits the formation of 1,2-diol methyl ether impurities, and improves product quality;

[0030] 2) Both the epoxidation reaction and the hydration reaction are fixed-bed continuous reactions, which realizes the continuous production of 1,2-diol, simplifies the production process and improves production efficiency;

[0031] 3) No salt-containing wastewater or acidic wastewater is discharged during the production process, no formic acid is used in the epoxidation reaction stage, and the reaction medium methanol can be recycled and reused after the epoxidation reaction is completed, which will not cause environmental pollution and realize green production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A process flow chart of the synthesis of 1,2-diol by catalysis of titanium silicon molecular sieve provided in an embodiment of the present invention;

[0033] Figure 2 It is the gas chromatogram of 1,2-epoxyhexane;

[0034] Figure 3 This is the gas chromatogram of 1,2-hexanediol. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0037] Example 1

[0038] like Figure 1-3 As shown, a method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve provided by one embodiment of the present invention comprises the following steps:

[0039] Step 1: Olefin epoxidation

[0040] Methanol, hydrogen peroxide solution and alkaline additive are prepared into a homogeneous mixed solution, which is mixed with raw olefin in a mixing tank and then injected into a fixed bed reactor for epoxidation reaction catalyzed by titanium silicon molecular sieve to generate 1,2-epoxyalkane solution;

[0041] Step 2: 1,2-Alkylene Oxide Hydration

[0042] After the 1,2-alkylene oxide solution is separated (i.e., the methanol, olefin, and alkylene oxide mixed solution are separated), the substrate olefin and the solvent methanol are recycled, and the 1,2-alkylene oxide and water react with each other in a fixed bed reactor under the action of an ion exchange resin catalyst to generate 1,2-diol;

[0043] Step 3: Purification of 1,2-diol

[0044] The hydration product is sent to a distillation tower for dehydration and impurity removal to obtain a high-purity, odorless 1,2-diol product.

[0045] Wherein, in step 1, the amount of alkaline additive added is 0% of the mass of hydrogen peroxide; the raw olefin is 1-pentene; the titanium silicon molecular sieve catalyst is a cylindrical molecular sieve with an MFI topological structure; the olefin epoxidation reaction is continuously carried out in a fixed bed reactor, and the feeding method is upper feeding and lower discharging; the reaction temperature is 5°C, the pressure is 0 Bar, the mass space velocity is 0.5, the molar ratio of olefin to hydrogen peroxide raw materials is 1.2:1, and the mass of methanol added is 3 times the mass of hydrogen peroxide solution.

[0046] In step 2, the ion exchange resin catalyst is a macroporous acidic ion exchange resin catalyst; the hydration reaction of 1,2-alkylene oxide is continuously carried out in a fixed bed reactor, and the feeding method is upper feeding and lower discharging; water and 1,2-alkylene oxide are introduced into the fixed bed reactor at a molar ratio of 15:1, the reaction temperature is 10°C, and the mass space velocity is 0.5.

[0047] Example 2

[0048] like Figure 1-3 As shown, the difference from Example 1 is that:

[0049] In step 1, the alkaline additive is ammonia water, and the amount of the alkaline additive added is 0.01% of the mass of hydrogen peroxide; the raw olefin is 1-hexene; the titanium silicalite molecular sieve catalyst is a spherical titanium silicalite molecular sieve with an MWW topological structure; the olefin epoxidation reaction is continuously carried out in a fixed bed reactor, and the feeding method is bottom feeding and top discharging; the reaction temperature is 80°C, the pressure is 50 Bar, the mass space velocity is 6, the molar ratio of olefin to hydrogen peroxide raw materials is 2.0:1, and the mass of methanol added is 6 times the mass of hydrogen peroxide solution.

[0050] In step 2, the hydration reaction of 1,2-alkylene oxide is continuously carried out in a fixed bed reactor, and the feeding method is bottom feeding and top discharging; water and 1,2-alkylene oxide are injected into the fixed bed reactor at a molar ratio of 30:1, the reaction temperature is 80°C, and the mass space velocity is 6.

[0051] Example 3

[0052] like Figure 1-3 As shown, the difference from Example 1 is that:

[0053] In step 1, the alkaline additive is an alkaline ammonium salt, and the amount of the alkaline additive added is 0.005% of the mass of hydrogen peroxide; the raw olefin is 1-octene; the titanium silicalite molecular sieve catalyst is a combination of a cylindrical molecular sieve with an MFI topological structure and a spherical titanium silicalite molecular sieve with an MWW topological structure; the reaction temperature is 10°C, the mass space velocity is 1, and the molar ratio of the olefin to the hydrogen peroxide raw materials is 1.5:1.

[0054] In step 2, the hydration reaction temperature is 20°C and the mass space velocity is 1.

[0055] Example 4

[0056] like Figure 1-3 As shown, the difference from Example 1 is that:

[0057] In step one, the alkaline additive is a combination of ammonia water and alkaline ammonium salt, and the amount of the alkaline additive added is 0.005% of the mass of hydrogen peroxide; the raw olefin is 1-hexene; the titanium silicalite molecular sieve catalyst is a combination of a cylindrical molecular sieve with an MFI topological structure and a spherical titanium silicalite molecular sieve with an MWW topological structure; the olefin epoxidation reaction is continuously carried out in a fixed bed reactor, and the feeding method is bottom feeding and top discharging; the reaction temperature is 60°C, the mass space velocity is 5, the molar ratio of the olefin to the hydrogen peroxide raw materials is 2.0:1, and the mass of the added methanol is 5 times the mass of the hydrogen peroxide solution.

[0058] In step 2, the hydration reaction of 1,2-epoxyalkylene is continuously carried out in a fixed bed reactor, and the feeding method is bottom feeding and top discharging; the molar ratio of water to 1,2-epoxyalkylene is 25:1, the hydration reaction temperature is 70°C, and the mass space velocity is 5.

[0059] The present invention selects the molar ratio of raw materials, mass space velocity, reaction temperature and the like as influencing factors of the selectivity of 1,2-epoxyhexane.

[0060] In Examples 1-7 shown in Table 1 below, 1-hexene, 30% hydrogen peroxide and methanol in a fixed ratio are injected into a fixed bed reactor at a mass space velocity of 3.0, the reaction temperature is controlled by adjusting the temperature of the circulating medium in the reactor interlayer, and the materials are collected after passing through the catalyst bed inside the reactor, and are separated and removed to remove hexene and methanol and then analyzed by gas chromatography.

[0061] Table 1 Selectivity of 1,2-epoxyhexane under different parameters of Examples 1-7

[0062]

[0063]

[0064] In Examples 8-13 shown in Table 2 below, a fixed ratio of 1-hexene, 30% hydrogen peroxide and methanol are injected into a fixed bed reactor, 27° C. circulating water is passed through the reactor interlayer, and the space velocity is changed by adjusting the flow rate of the horizontal feed pump. The materials are collected after passing through the catalyst bed inside the reactor, and are separated and removed Hexene and methanol and then analyzed by gas chromatography.

[0065] Table 2 Selectivity of 1,2-epoxyhexane under different parameters of Examples 8-13

[0066]

[0067] Examples 14-19 shown in Table 3 below are for preparing different proportions of 1-hexene, 30% hydrogen peroxide and methanol solution, which are pumped into a fixed bed reactor through a horizontal feed pump, and 27°C circulating water is passed through the reactor interlayer. The materials are collected after passing through the catalyst bed inside the reactor, and are separated to remove hexene and methanol and then analyzed by gas chromatography.

[0068] Table 3 Selectivity of 1,2-epoxyhexane under different parameters of Examples 14-19

[0069]

[0070]

[0071] The present invention selects the molar ratio of raw materials, mass space velocity, reaction temperature and the like as influencing factors of the selectivity and yield of 1,2-hexanediol.

[0072] In Examples 20-26 shown in Table 4 below, a certain molar ratio of water / 1.2-epoxyhexane is injected into a fixed bed reactor, a circulating medium of a certain temperature is passed through the reactor interlayer to control the reaction temperature, and the mass space velocity is controlled by two horizontal flow feed pumps connected to the water raw material tank and the 1.2-epoxyhexane raw material tank, respectively. The material is collected after passing through the catalyst bed inside the reactor, and the final product is obtained after dehydration and decontamination.

[0073] Table 4 1,2-hexanediol yield and 1,2-epoxyhexane selectivity of Examples 20-26 under different parameters

[0074]

[0075] The above embodiment of the present invention provides a method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve. The product yield of 1,2-diol is greater than 92%, and the product is odorless. The introduction of alkaline additives further improves the selectivity of the epoxidation reaction, inhibits the generation of 1,2-diol methyl ether impurities, and improves product quality. The epoxidation reaction and the hydration reaction are both fixed-bed continuous reactions, which realizes the continuous production of 1,2-diol, simplifies the production process, and improves production efficiency. No salt-containing wastewater or acidic wastewater is discharged during the production process, no formic acid is used in the epoxidation reaction stage, and the reaction medium methanol can be recovered and reused after the epoxidation reaction is completed, which will not cause environmental pollution and realize green production.

[0076] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve, characterized in that: The following steps are involved: Step 1: Olefin epoxidation Methanol, hydrogen peroxide solution and alkaline additive are prepared into a homogeneous mixed solution, which is mixed with raw olefin in a mixing tank and then injected into a fixed bed reactor for epoxidation reaction catalyzed by titanium silicon molecular sieve to generate 1,2-epoxyalkane solution; Step 2: 1,2-Alkylene Oxide Hydration After the 1,2-epoxyalkylene solution is separated, the substrate olefin and the solvent methanol are recycled, and the 1,2-epoxyalkylene and water react with the ion exchange resin catalyst in a fixed bed reactor to generate 1,2-diol; Step 3: Purification of 1,2-diol The hydration product is sent to a distillation tower for dehydration and impurity removal to obtain a high-purity, odorless 1,2-diol product.

2. The method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve according to claim 1, characterized in that: In step 1, the alkaline additive is one of ammonia water, alkaline ammonium salt, organic amine or a combination thereof, and the amount of the alkaline additive added is 0-0.01% of the mass of hydrogen peroxide.

3. The method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve according to claim 2, characterized in that: In step 1, the raw material olefin is 1-pentene, 1-hexene or 1-octene.

4. The method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve according to claim 3, characterized in that: In step 1, the titanium silicalite catalyst is one or a combination of cylindrical or spherical titanium silicalite with MFI or MWW topological structure.

5. The method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve according to claim 4, characterized in that: In step 1, the olefin epoxidation reaction is continuously carried out in a fixed bed reactor, and the feeding method is upper feeding and lower discharging or lower feeding and upper discharging; The reaction temperature is 5-80°C, the pressure is 0-50 Bar, the mass space velocity is 0.5-6, the molar ratio of olefin to hydrogen peroxide raw materials is 1.2-2.0:1, and the added mass of methanol is 3-6 times the mass of the hydrogen peroxide solution.

6. The method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve according to claim 5, characterized in that: In step 1, the reaction temperature is 10-60° C., the mass space velocity is 1-5, the molar ratio of olefin to hydrogen peroxide raw materials is 1.5-2.0:1, and the mass of methanol added is 3-5 times the mass of the hydrogen peroxide solution.

7. The method for synthesizing 1,2-diol catalyzed by titanium silicon molecular sieve according to any one of claims 1 to 6, characterized in that: In step 2, the ion exchange resin catalyst is a macroporous acidic ion exchange resin catalyst.

8. The method for synthesizing 1,2-diol by catalysis of titanium silicon molecular sieve according to claim 7, characterized in that: In step 2, the hydration reaction of 1,2-alkylene oxide is continuously carried out in a fixed bed reactor, and the feeding method is upper feeding and lower discharging or lower feeding and upper discharging; Water and 1,2-epoxyalkylene are introduced into a fixed bed reactor at a molar ratio of 15-30:1, the reaction temperature is 10-80°C, and the mass space velocity is 0.5-6.

9. The method for synthesizing 1,2-diol catalyzed by titanium silicon molecular sieve according to claim 8, characterized in that: In step 2, the molar ratio of water to 1,2-epoxyalkane is 15-25:1, the hydration reaction temperature is 20-70°C, and the mass space velocity is 1-5.

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