Method for continuously synthesizing 2-chloropropane

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a method for continuously synthesizing 2-chloropropane, which comprises the following steps: uniformly mixing preheated hydrogen chloride gas and vaporized isopropanol through a mixer, introducing into a fixed bed reactor filled with a solid catalyst, and contacting with the catalyst to start reaction to generate mixed gas containing 2-chloropropane; and carrying out gas-liquid separation on the mixed gas containing 2-chloropropane, and standing and layering the liquid phase to obtain the 2-chloropropane product on the upper layer. According to the method, the problem of continuous synthesis of 2-chloropropane is solved, the production efficiency is greatly improved, meanwhile, the problem that high-price special material equipment is needed in the reaction is solved, and the production cost is reduced. The problems of high reaction temperature, low selectivity and low yield are solved, the product purity of the reaction exceeds 99%, and the yield reaches more than 98.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for continuously synthesizing 2-chloropropane. Background Art

[0002] 2-Chloropropane, also known as isopropyl chloride and isopropyl chloride, is an important organic chemical raw material and an important organic intermediate synthetic body. Due to the active chlorine atom in its structure, it can react with aromatic amines, fatty amines, etc. to form corresponding amines. 2-Chloropropane can be used as an intermediate for the synthesis of medicines, pesticides, additives, etc., and can be used as one of the raw materials for the preparation of catalyst components for polypropylene. In addition, 2-chloropropane can be used as a paint diluent, a metal scrubber, etc. In different fields, it can also be transformed into various products and intermediates through a series of methods such as dehydrochlorination, amination, chlorination, pressurized hydrolysis, and laser conversion after fluorination. It has a wide range of uses. Therefore, the research on the refining and utilization of 2-chloropropane products has great market value potential.

[0003] The main synthesis technologies of 2-chloropropane include propylene and hydrogen chloride method, hydrochloric acid and isopropanol method or hydrogen chloride isopropanol method. The current mainstream technology is intermittent kettle reaction, which can only achieve high reaction yield and selectivity at a reaction temperature below 100°C. The intermittent reaction efficiency is low, and the water vapor generated by the reaction itself at low temperatures is easy to liquefy and react with hydrogen chloride to form hydrochloric acid, which corrodes the reactor, and it is necessary to spend a high price to purchase special materials and equipment.

[0004] Patent CN1596238A discloses a method for synthesizing 2-chloropropane. Under the conditions of temperature of 40-60°C and absolute pressure of 1-3 atmospheres, iron or pre-halogenated aluminum oxide is used as a catalyst to prepare 2-chloropropane by reacting propylene and hydrogen chloride, with a yield of 86%-94%. Although this method has a high yield and can achieve continuous synthesis, it has extremely strict requirements on the water content of the raw materials under pressurized and low-temperature reaction conditions, and requires the use of expensive anti-corrosion equipment. In addition, the reaction raw material propylene is very prone to explosion, which brings potential dangers to transportation, storage and production.

[0005] Patent CN109053364A discloses a method for synthesizing 2-chloropropane using hydrogen chloride gas and isopropanol. The reaction is carried out using a reactor, and the reaction rate can reach 92%. However, the method requires first evacuation, and then filling with inert gas to maintain pressure. Thereafter, alcohol and catalyst need to be added under pressure. Alcohol can be transported under pressure by a pump, but the catalyst is a solid particle and it is difficult to enter under pressure. In addition, after hydrogen chloride enters and during the reaction process, the pressure is maintained by inputting or removing inert gas. When the pressure is overloaded, the pressure is released and the material will also flow out, resulting in the inability to control the amount of material, and there are safety hazards. The method is complicated to operate, the process is difficult to control, and continuous production is not possible.

[0006] In addition, isopropanol and hydrochloric acid can be used to produce 2-chloropropane intermittently through a reactor, but this method has a low yield, complicated subsequent operations, and cannot be produced continuously. Summary of the invention

[0007] The object of the present invention is to provide a method for continuously synthesizing 2-chloropropane in view of the defects of the above method. The method uses isopropanol and hydrogen chloride as raw materials and utilizes a solid catalyst to continuously produce 2-chloropropane in a fixed bed reactor.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions: A method for continuously synthesizing 2-chloropropane comprises the following steps: (1) Preheated hydrogen chloride gas and vaporized isopropanol are mixed uniformly in a mixer, and then introduced into a fixed bed reactor loaded with a solid catalyst to start a reaction with the catalyst to generate a mixed gas containing 2-chloropropane; wherein the molar ratio of isopropanol to hydrogen chloride is 1:1-1.20, the reaction temperature is 120°C-180°C, and the reaction pressure is normal pressure; and the solid catalyst is a kaolin catalyst; (2) The mixed gas containing 2-chloropropane is separated into gas and liquid, and the liquid phase is allowed to stand and separate into layers. The upper layer is the 2-chloropropane product.

[0009] Preferably, the space velocity of the reaction in step (1) is 0.2-0.4 m / s. 3 ·h -1 Before the reaction, the hydrogen chloride gas is preheated to the reaction temperature, and the isopropanol is vaporized to the reaction temperature.

[0010] Preferably, the reaction temperature in step (1) is 140-170°C, more preferably 160-170°C.

[0011] Preferably, the molar ratio of isopropanol to hydrogen chloride in step (1) is 1:1.04-1.16, and more preferably 1:1.04-1.08. This molar ratio of reactants can ensure the highest yield and effectively control the amount of waste hydrochloric acid produced.

[0012] Preferably, the mixed gas containing 2-chloropropane in step (2) enters the gas-liquid separation tank in gaseous form from the bottom of the fixed bed reactor for condensation, and the liquid phase in the gas-liquid separation tank includes an aqueous phase and an organic phase, wherein the aqueous phase is mainly hydrochloric acid and unreacted alcohol, and the organic phase is 2-chloropropane and a small amount of by-products such as olefins and ethers; a very small amount of olefins and hydrogen chloride enter the tail gas absorption device. Subsequently, all the liquid phases in the gas-liquid separation tank enter the buffer tank for static stratification, and the main product in the upper layer is 2-chloropropane.

[0013] Preferably, the gas-liquid separation tank is made of 316L material, and the places in contact with the material are lined with fluorine. Preferably, the condensation temperature in the gas-liquid separation tank is -30°C to -15°C.

[0014] Preferably, the kaolin catalyst is composed of kaolin, sesbania powder, and nitric acid, wherein the mass percentage of sesbania powder is 2.5-3.0wt%, the mass percentage of nitric acid is 5-13wt%, and the rest is kaolin. Further preferably, the mass percentage of sesbania powder is 2.6-2.65wt%, and the mass percentage of nitric acid is 8-12wt%.

[0015] Preferably, the molar ratio of silicon to aluminum in the kaolin catalyst is 1-2.5:1, more preferably the molar ratio of silicon to aluminum is 1.25-2.5:1, and even more preferably the molar ratio of silicon to aluminum is 2-2.25:1.

[0016] Preferably, the kaolin catalyst is prepared by mixing sesbania powder, kaolin and nitric acid solution and then processing and molding. The concentration of the nitric acid solution is 15-30wt%, preferably 15-25wt%. The mass ratio of sesbania powder to kaolin is 0.01-0.1:1, preferably 0.02-0.06:1, and more preferably 0.03:1; the mass ratio of the sum of the mass of sesbania powder and kaolin to the nitric acid solution is 1:0.15-1.15, preferably 1:0.35-0.75.

[0017] The beneficial effects of the present invention are: The method for synthesizing 2-chloropropane of the present invention is a continuous method, which uses isopropanol and hydrogen chloride as raw materials and uses a solid catalyst to continuously react and synthesize 2-chloropropane in a fixed bed reactor. The present invention achieves high reaction yield and selectivity while ensuring a certain temperature to avoid equipment corrosion.

[0018] The invention solves the problem of continuous synthesis of 2-chloropropane, greatly improves production efficiency, and simultaneously solves the problem that the reaction requires expensive special material equipment, thereby reducing production costs.

[0019] The present invention prepares a simple and efficient catalyst through cheap and readily available kaolin, solves the efficiency problems of high reaction temperature, low selectivity and low yield. The product purity of the reaction exceeds 99% and the yield reaches more than 98.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The gas chromatogram of the product obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below by means of specific examples and in conjunction with the accompanying drawings. The raw materials used in the examples and comparative examples of the present invention can all be purchased.

[0022] In the present invention, the fixed bed reactor is a jacketed tubular reactor, and the inner diameter of the tube is Φ38mm×2200mm. The material of the fixed bed reactor is 316L. The loading amount of the solid catalyst in the fixed bed reactor is 1L, and the solid catalyst is evenly loaded into the fixed bed reactor using a funnel, and the side wall of the reactor is continuously knocked with a leather hammer during the loading process to make the catalyst loading uniform, so as to prevent the "bridging" phenomenon.

[0023] The kaolin catalyst of the present invention can be prepared by the following steps: 1) Grinding and mixing sesbania powder and kaolin in a mass ratio of 0.01-0.1:1 to obtain a mixed powder; 2) uniformly mixing the mixed powder obtained in step 1) and a nitric acid solution having a concentration of 15-30 wt% at a material mass ratio of 1:0.15-1.15; 3) The materials uniformly mixed in step 2) are further kneaded using a kneader, and then processed and shaped using an extruder, and then dried and calcined to obtain a kaolin catalyst.

[0024] Preferably, in step 1), the mass ratio of sesbania powder to kaolin is 0.02-0.06:1, more preferably 0.03:1. A ball mill is used for grinding, with a grinding speed of 500-1200 rpm and a grinding time of 20-50 minutes.

[0025] Preferably, the concentration of the nitric acid solution in step 2) is 15-25wt%, and the material mass ratio is 1:0.35-0.75.

[0026] Preferably, in step 3), the mixed material in step 2) is further kneaded using a kneading machine to increase the strength of the catalyst before molding. The kneading machine is a twin-screw kneading machine, and the kneading time is 0.5-1.5 hours. The extruder is a twin-screw extruder. The extruder extrude the material into catalysts of different shapes, and cut them into suitable lengths by a strip cutter at the front section of the extruder.

[0027] Preferably, the drying temperature in step 3) is 80-140°C, and the drying time is 8-24 hours; more preferably, the drying temperature is 95-115°C, and the drying time is 10-16 hours. The calcination temperature is 300-700°C, and the calcination time is 5-15 hours; more preferably, the calcination temperature is 400-600°C, and the calcination time is 6-12 hours.

[0028] Example 1 A method for continuously synthesizing 2-chloropropane, the specific steps are as follows: (1) Preparation of catalyst 400 g of kaolin with a silicon-aluminum molar ratio of 2.25:1 and 12 g of sesbania powder were added to a ball mill at 800 rpm and ground for 45 minutes; Then, 200 g of 20% nitric acid solution is evenly sprayed on the ground powder, and mixed while spraying; The mixed material was transferred to a kneader and further kneaded for 1.2 hours, and then processed into a rod-shaped catalyst with a four-leaf clover-shaped cross section using a twin-screw extruder, with a length of 5-6 mm and a maximum cross-sectional diameter of 4-5 mm; The formed catalyst was dried at 110° C. for 12 hours, placed in a muffle furnace, and calcined at 500° C. for 8 hours to obtain a finished catalyst.

[0029] (2) 1L (about 350g) of catalyst was loaded into a tubular reactor with a diameter of Φ38mm×2200mm. 120g of inert porcelain balls were added to the upper end of the tubular reactor to further mix and preheat the materials.

[0030] (3) Hydrogen chloride and isopropanol are preheated and vaporized to 160°C in a preheater and vaporizer, respectively, and then mixed in a mixer before entering a fixed bed reactor for reaction. The feed molar ratio of hydrogen chloride to isopropanol is 1.04:1, the reactor bed temperature is 160°C, and the reaction pressure is atmospheric pressure. The reaction space velocity is 0.32 m / s. 3 ·h -1 .

[0031] (4) The mixed gas after the reaction is discharged from the bottom of the reactor and enters the gas-liquid separation tank. After the gas-liquid separation, the liquid phase enters the buffer tank for static stratification. The upper liquid is the product 2-chloropropane. Its gas chromatogram is shown in Figure 1 shown.

[0032] Example 2 The difference from Example 1 is that the molar ratio of isopropanol to hydrogen chloride in step (3) is 1:1, and the other steps are the same as Example 1.

[0033] Example 3 The difference from Example 1 is that in step (3), the molar ratio of isopropanol to hydrogen chloride is 1:1.08, and the other steps are the same as Example 1.

[0034] Example 4 The difference from Example 1 is that the molar ratio of isopropanol to hydrogen chloride in step (3) is 1:1.12, and the other steps are the same as Example 1.

[0035] Example 5 The difference from Example 1 is that in step (3), the molar ratio of isopropanol to hydrogen chloride is 1:1.16, and the other steps are the same as Example 1.

[0036] Example 6 The difference from Example 1 is that the molar ratio of isopropanol to hydrogen chloride in step (3) is 1:1.2, and the other steps are the same as Example 1.

[0037] Example 7 The difference from Example 1 is that the bed temperature in step (3) is 125°C, and the other steps are the same as Example 1.

[0038] Example 8 The difference from Example 1 is that the bed temperature in step (3) is 140° C., and the other steps are the same as Example 1.

[0039] Example 9 The difference from Example 1 is that the bed temperature in step (3) is 150°C, and the other steps are the same as Example 1.

[0040] Example 10 The difference from Example 1 is that the bed temperature in step (3) is 170°C, and the other steps are the same as Example 1.

[0041] Embodiment 11 The difference from Example 1 is that the silicon-aluminum ratio of the kaolin used in step (1) is 1.25:1, and the other steps are the same as Example 1.

[0042] Example 12 The difference from Example 1 is that the silicon-aluminum ratio of the kaolin used in step (1) is 1.5:1, and the other steps are the same as Example 1.

[0043] Example 13 The difference from Example 1 is that the silicon-aluminum ratio of the kaolin used in step (1) is 1.75:1, and the other steps are the same as Example 1.

[0044] Embodiment 14 The difference from Example 1 is that the silicon-aluminum ratio of the kaolin used in step (1) is 2:1, and the other steps are the same as Example 1.

[0045] Embodiment 15 The difference from Example 1 is that the silicon-aluminum ratio of the kaolin used in step (1) is 2.5:1, and the other steps are the same as Example 1.

[0046] Example 16 The difference from Example 1 is that the concentration of nitric acid used in step (1) is 15 wt %. The other steps are the same as Example 1.

[0047] Embodiment 17 The difference from Example 1 is that the concentration of nitric acid used in step (1) is 25 wt %. The other steps are the same as Example 1.

[0048] Embodiment 18 The difference from Example 1 is that the concentration of nitric acid used in step (1) is 30 wt %. The other steps are the same as Example 1.

[0049] Comparative Example 1 The difference from Example 1 is that the molar ratio of isopropanol to hydrogen chloride in step (3) is 1:0.85, and the other steps are the same as Example 1.

[0050] Comparative Example 2 The difference from Example 1 is that the bed temperature in step (3) is 185°C, and the other steps are the same as Example 1.

[0051] Comparative Example 3 The difference from Example 1 is that the silicon-aluminum ratio of the kaolin used is 3:1, and the other steps are the same as Example 1.

[0052] Comparative Example 4 The difference from Example 1 is that 800 g of nitric acid solution with a mass concentration of 5 wt % is used, and the other steps are the same as those in Example 1.

[0053] Comparative Example 5 The difference from Example 1 is that 100 g of nitric acid solution with a mass concentration of 40 wt % is used, and the other steps are the same as those in Example 1.

[0054] Comparative Example 6 The difference from Example 1 is that the catalyst used is a purchased finished product of four-leaf clover rod-shaped pure silicon molecular sieve SBA-15, and the other steps are the same as Example 1.

[0055] Comparative Example 7 The difference from Example 1 is that the catalyst used is a purchased finished product, four-leaf clover rod-shaped Y-type molecular sieve with a silicon-aluminum ratio of 2.25:1, and the other steps are the same as Example 1.

[0056] Comparative Example 8 The difference from Example 1 is that the catalyst used is a purchased finished product, four-leaf clover stick-shaped pure alumina catalyst, and the other steps are the same as Example 1.

[0057] Comparative Example 9 The catalyst was prepared with reference to Example 1 of patent CN 118666633 A, and other conditions were the same as Example 1 of the present invention.

[0058] The yield of 2-chloropropane was calculated and the purity of the obtained product was tested. The reaction conditions and results of each product are shown in Table 1: Table 1 Reaction conditions and results

[0059] It can be seen from the experimental results in Table 1 that the catalyst yield of Example 1 can reach 98.91% and the purity can reach 99.679%. Compared with Comparative Examples 6, 7, and 8, it can be seen that the pure silicon molecular sieve (Comparative Example 6) has a weak catalytic activity for the reaction; and the molecular sieve containing silicon and aluminum has the same silicon-aluminum ratio as the kaolin catalyst, but the composition of the catalyst is different and the catalyst activity is also different. At high temperatures, Comparative Examples 7 and 8 are more likely to cause isopropanol to crack to produce propylene, resulting in a reduction in the yield and purity of 2-chloropropane, and the cost of both is also much higher than the kaolin catalyst described in the present invention. The catalyst of Comparative Example 9 has a good effect on the production of 1-chlorobutane in a fixed bed reactor, but it is not effective for the synthesis of 2-chloropropane because the catalyst makes it easy for isopropanol to crack into propylene, and the product yield and purity decrease.

[0060] The present invention controls the number and strength of the catalyst acid sites by controlling the composition of the kaolin catalyst, the content of silicon and aluminum, the concentration of nitric acid during the molding process, etc., and thus prepares a kaolin catalyst suitable for preparing 2-chloropropane at a relatively high temperature. The existing pure silicon catalyst has weak acidity and poor catalytic performance; the catalyst acidity of pure alumina is too strong, and the acidity of the silicon-aluminum molecular sieve is difficult to control. The cost of the kaolin catalyst of the present invention is lower than the above three. The present invention realizes the control of the catalyst and the acid strength and acid sites through simple, effective and low-cost raw materials, and develops a catalyst suitable for the catalyst at a relatively high temperature.

[0061] In summary, the method for synthesizing 2-chloropropane developed by the present invention not only realizes the continuous synthesis of 2-chloropropane by using isopropanol and hydrogen chloride in a fixed bed reactor, but also solves the problems of low high-temperature yield, low purity and corrosion of low-temperature equipment requiring replacement of expensive corrosion-resistant equipment. A safe, economical and efficient method for synthesizing 2-chloropropane is provided.

Claims

1. A method for continuously synthesizing 2-chloropropane, characterized in that: The following steps are involved: (1) Preheated hydrogen chloride gas and vaporized isopropanol are mixed uniformly in a mixer, and then introduced into a fixed bed reactor loaded with a solid catalyst to start a reaction with the catalyst to generate a mixed gas containing 2-chloropropane; wherein the molar ratio of isopropanol to hydrogen chloride is 1:1-1.20, the reaction temperature is 120°C-180°C, and the reaction pressure is normal pressure; and the solid catalyst is a kaolin catalyst; (2) The mixed gas containing 2-chloropropane is separated into gas and liquid, and the liquid phase is allowed to stand and separate into layers. The upper layer is the 2-chloropropane product.

2. The method for continuously synthesizing 2-chloropropane according to claim 1, characterized in that: The space velocity of the reaction in step (1) is 0.2~0.4m 3 ·h -1 .

3. The method for continuously synthesizing 2-chloropropane according to claim 1, characterized in that: The reaction temperature in step (1) is 140-170°C.

4. The method for continuously synthesizing 2-chloropropane according to claim 1, characterized in that: The molar ratio of isopropanol to hydrogen chloride in step (1) is 1:1.04-1.

16.

5. The method for continuously synthesizing 2-chloropropane according to any one of claims 3 or 4, characterized in that: The reaction temperature in step (1) is 160-170° C., and the molar ratio of isopropanol to hydrogen chloride is 1:1.04-1.

08.

6. The method for continuous synthesis of 2-chloropropane according to claim 1, characterized in that: The kaolin catalyst consists of kaolin, sesbania powder and nitric acid, wherein the mass percentage of the sesbania powder is 2.5-3.0wt%, the mass percentage of the nitric acid is 5-13wt%, and the rest is kaolin.

7. The method for continuously synthesizing 2-chloropropane according to claim 1, characterized in that: The molar ratio of silicon to aluminum in the kaolin catalyst is 1-2.5:

1.

8. The method for continuously synthesizing 2-chloropropane according to claim 7, characterized in that: The molar ratio of silicon to aluminum in the kaolin catalyst is 1.25-2.5:

1.

9. The method for continuously synthesizing 2-chloropropane according to claim 1, characterized in that: The kaolin catalyst is prepared by mixing sesbania powder, kaolin and nitric acid solution and then processing and molding.

10. The method for continuously synthesizing 2-chloropropane according to claim 9, characterized in that: The concentration of the nitric acid solution is 15-30wt%.

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