Method for preparing trichloroacetone by utilizing molecular sieve photocatalytic reaction

Abstract

The invention relates to the technical field of organic synthesis, and discloses a method for preparing trichloroacetone by utilizing a molecular sieve photocatalytic reaction. The method specifically comprises the steps that acetone is activated through a composite catalyst, chlorine is subjected to photocatalysis to form chlorine free radicals, alpha-H of acetone and the chlorine free radicals (Cl.) are catalyzed in micro-channels of a molecular sieve in a high-activity state to be subjected to a substitution reaction, the conversion rate and selectivity of the reaction can be remarkably improved through the molecular sieve catalyst, and more 1, 1, 3-trichloroacetone can be selectively obtained. A molecular sieve is used as a reaction medium, so that reaction liquid and chlorine are adsorbed in micro-pore channels and are in full contact to generate a rapid substitution reaction, and the influence of a gas-liquid barrier of a reaction kettle in a traditional one-pot method on reaction efficiency and homogeneity is avoided. The method for preparing the 1, 1, 3-trichloroacetone is high in efficiency, yield and purity, reaction progress parameters are easy to regulate and control, and the method is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for preparing trichloroacetone by utilizing a molecular sieve photocatalytic reaction. Background Art

[0002] 1,1,3-Trichloroacetone is a colorless, transparent, oily liquid at room temperature and pressure. It is commonly used as an intermediate in organic synthesis and pharmaceutical chemistry, and is mostly used for the structural modification of drug molecules and bioactive molecules.

[0003] 1,1,3-Trichloroacetone is a key intermediate in the production of folic acid. As an essential water-soluble B vitamin, folic acid plays a crucial role in many important physiological and metabolic functions, including nucleotide synthesis and homocysteine ​​remethylation. As a carrier of one-carbon units, folic acid is a crucial methyl group donor in the body, participating in cell growth and tissue repair, and is an essential nutrient for growth and reproduction. Therefore, folic acid plays a crucial role in rapid cell division and growth processes, such as infant development and pregnancy. Folic acid promotes the maturation of young cells in the bone marrow into normal red blood cells, thereby preventing anemia. Because folic acid plays a crucial role in neural tube formation, adequate pre-conception folic acid intake is crucial for normal fetal development. Folic acid deficiency during pregnancy can affect fetal nervous system development. Studies have shown that adequate folic acid supplementation during and before pregnancy can reduce the incidence of neural tube defects and cleft lip.

[0004] Currently, the 1,1,3-trichloroacetone produced on an industrial scale typically has a purity level below 65%, and contains a high number of side products. This results in a high level of impurities when used in folic acid production, making it difficult to meet the purity requirements of international pharmacopoeias. Furthermore, low-purity 1,1,3-trichloroacetone used in folic acid production produces wastewater with high chloride content, making it difficult to treat. Therefore, high-purity 1,1,3-trichloroacetone is urgently needed for folic acid production.

[0005] According to publicly available technology, the current method for preparing 1,1,3-trichloroacetone primarily utilizes acetone chlorination. The hydrogen atoms at the α-carbon of the acetone molecule, influenced by the carbonyl group, are highly susceptible to substitution reactions with halogen elements. Due to the high reactivity of chlorine, chlorination initially occurs at the α-carbon methyl group (position 1), producing monochloroacetone. Further chlorination, due to the electron-withdrawing effect of the Cl atom, makes the remaining hydrogen atoms at the 1-position methyl group more reactive and more easily replaced, yielding 1,1-dichloroacetone. Substitution of the other methyl group (position 3) is slower, resulting in less 1,3-dichloroacetone. Further chlorination using excess chlorine results in a higher yield of 1,1,1-trichloroacetone, resulting in poor selectivity for 1,1,3-trichloroacetone. This results in a low content and yield of 1,1,3-trichloroacetone.

[0006] Clearly, selectivity is a key factor in the chlorination process to produce 1,1,3-trichloroacetone. When monochloroacetone is further chlorinated, 1,1-dichloroacetone is the dominant product, resulting in a decrease in 1,3-dichloroacetone. Therefore, to increase the content and yield of 1,1,3-trichloroacetone, optimizing reaction conditions and using catalysts can improve the selectivity of the chlorination reaction of the target compound and reduce side reactions.

[0007] Patent document CN116283525B discloses a method for preparing 1,1,3-trichloroacetone. Acetone is used as the raw material and reacted with the chlorination reagent N-chlorosuccinimide under the catalysis of 1-methylpyrazole to produce 1,1,3-trichloroacetone. The reaction time is 9-12 hours, and the purity of 1,1,3-trichloroacetone is over 79.2%, with a yield of over 62.0%. While the use of a catalyst improves the yield and purity of 1,1,3-trichloroacetone, a significant amount of 1,1,1-trichloroacetone byproduct is still produced.

[0008] Patent document CN107602364B discloses a method for preparing 1,1,3-trichloroacetone by chlorinating acetone. Using triethylamine as a catalyst and an alcohol as a solvent, this method significantly improves the selectivity of chlorinating 1,1-dichloroacetone, increases the formation of 1,1,3-trichloroacetone, and suppresses the formation of 1,1,1-trichloroacetone. This method uses gas chromatography to monitor the reaction progress in both the first and second chlorination stages, which increases the difficulty and complexity of control.

[0009] Ideally, if more 1,3-dichloroacetone is produced during the second chlorination of acetone, the final 1,1,3-trichloroacetone content and yield would be significantly increased. Patent document CN100494147C discloses a method for preparing 1,3-dichloroacetone. Monochloroacetone is chlorinated in a strong acid and water using a platinum catalyst, resulting in acetone and 1,3-dichloroacetone. This method eliminates the formation of 1,1-dichloroacetone and offers high selectivity, but the catalyst costs are prohibitive, making industrial production difficult.

[0010] The existing method for preparing 1,1,3-trichloroacetone is a one-pot process, where chlorine gas is directly introduced into a stirred acetone solution. This reaction is difficult to control and inevitably results in the formation of various chlorinated ketone byproducts, such as 1,1,1-trichloroacetone, 1,1,3,3-tetrachloroacetone, and 1,1,1,3-tetrachloroacetone. Using catalysts alone to improve chlorination selectivity is extremely limited, resulting in low yield and purity of 1,1,3-trichloroacetone. Summary of the Invention

[0011] To address the problems of low purity, low yield, low preparation efficiency, and difficulty in stable control of batch production in the current preparation of 1,1,3-trichloroacetone, the present invention proposes a method for preparing trichloroacetone using a molecular sieve photocatalytic reaction. By increasing the activity of acetone and chlorine, the micropores of the molecular sieve serve as catalytic reaction channels, promoting the simultaneous replacement of chlorine free radicals (Cl·) and the hydrogen atoms of the two methyl groups of acetone, thereby improving the selectivity of the preparation of 1,1,3-trichloroacetone, enhancing the reaction efficiency and yield, and significantly reducing the generation of by-products.

[0012] To achieve the above object, the technical solution adopted by the present invention is:

[0013] A method for preparing trichloroacetone by using a molecular sieve photocatalytic reaction mainly comprises the following steps:

[0014] S1. Acetone and the composite catalyst were added to the reactor in a mass ratio of 100: (1-1.5), the stirring speed was adjusted to 50-80 rpm, and the stirring activation was performed for 15-20 min to obtain a pre-activated product; the composite catalyst was a composition of sodium ethoxide, N, N- dimethylacetamide and triethanolamine;

[0015] S2. Open the delivery valve and introduce the preactivated product from step S1 into a vertical reaction tower equipped with a molecular sieve. The preactivated product is completely adsorbed by the molecular sieve, which has a pore size of 6-10 angstroms. Chlorine gas activated by ultraviolet light is introduced into the bottom of the vertical reaction tower at a flow rate of 0.20-0.25 mol / min. The total amount of chlorine gas is measured at 2.5-3.0 times the molar amount of the preactivated product (acetone only). Chlorine gas gradually rises from the bottom of the vertical reaction tower and chlorinates the preactivated product in the micropores of the molecular sieve step by step.

[0016] S3. After ventilation is completed, continue the reaction for 0.5-1h. Check the density of the reaction liquid in each section. When it meets the standard, vacuum suction and desorption are performed, and trichloroacetone is collected in the receiving tank at the bottom of the vertical reaction tower.

[0017] Preferably, the composite catalyst is a composition of sodium ethoxide, N,N-dimethylacetamide, and triethanolamine in a mass ratio of 2:3:5. The alkaline composite catalyst is conducive to activating the α-H of acetone, and its hydrogen atoms are more easily activated and removed.

[0018] Preferably, an exhaust hole is provided on the upper part of the vertical reaction tower, which is connected to an external negative pressure absorption tank, so that the generated hydrogen chloride gas and a small amount of unreacted chlorine gas are immediately introduced into the absorption tank through the exhaust hole to form water absorption liquid and fix the discharge.

[0019] Preferably, the molecular sieve is a titanium silicalite molecular sieve with a pore size of 6-10 angstroms, in the form of microspheres with a diameter of 1-2 mm. Molecular sieves have a high specific surface area and a uniform microporous structure, providing a large number of active sites, thereby increasing the activity of the reactants. Titanium silicate molecular sieves attract chlorine molecules, making them more susceptible to substitution reactions with acetone.

[0020] Preferably, the molar ratio of the preactivated product (only acetone) to the chlorine introduced into the bottom of the tower is 1:2.8; if the chlorine dosage is too low, more dichloroacetone by-products will be produced. When the chlorine dosage is increased, deep chlorination products (such as 1,1,3,3-tetrachloroacetone and 1,1,1,3-tetrachloroacetone) will be formed, resulting in more impurities.

[0021] Preferably, the pressure of the chlorine gas introduced into the bottom of the tower is controlled at 0.01-0.05 MPa. By fine-tuning the flow rate and pressure of the chlorine gas, the rising speed of the chlorine gas from the bottom to the top of the tower is controlled, thereby controlling the reaction progress.

[0022] Preferably, the wavelength of the ultraviolet light source in step S2 is 365-450 nm; particularly preferably, a high-pressure mercury lamp is used to generate ultraviolet light with a wavelength of 404.7 nm and an optical power of 0.5-1.0 kW. After being irradiated by the ultraviolet light source, the chlorine gas enters the bottom of the tower, and the chlorine gas ultraviolet irradiation time is controlled to be 8-10 seconds.

[0023] Preferably, the vertical reaction tower is provided with one, two and three temperature control zones from bottom to top; the temperature control zones are temperature controlled by jackets and built-in circulating cooling pipes; the temperature control in the first section is 5-15°C, the temperature control in the second section is 20-30°C, and the temperature control in the third section is 45-50°C.

[0024] More preferably, the reaction liquid density is measured by sampling in the first, second, and third sections of the vertical reactor to serve as a basis for controlling the reaction progress. A preferred standard density of the reaction liquid is 1.43-1.48 g / mL. Once the reaction density in each section reaches the standard, vacuum desorption is initiated, and the crude acetone chlorination liquid is collected in a receiving tank at the bottom of the vertical reactor.

[0025] The traditional preparation of 1,1,3-trichloroacetone uses a one-pot method to pass chlorine gas into acetone. When the α-H on a methyl group of acetone is replaced by chlorine, the activity of the α-H at that point increases and it is more easily replaced, resulting in the production of 1,1-dichloroacetone, which in turn affects the selectivity of 1,1,3-trichloroacetone.

[0026] Unlike the one-pot method for preparing 1,1,3-trichloroacetone, this method uses a composite catalyst to reduce the activation energy of the hydrogen atoms on the acetone methyl groups, thereby increasing their activity and making them more readily available for chemical reactions. Simultaneously, chlorine gas undergoes photocatalytic homolysis into two chlorine radicals (Cl·), which selectively undergo substitution reactions with the lower-energy hydrogen atoms on the methyl groups. The molecular sieve's dispersing effect fully exposes the active sites of acetone, allowing the acetone to be fully dispersed within the molecular sieve. This allows for rapid substitution reactions with the chlorine radicals (Cl·), simultaneously replacing the hydrogen atoms on both methyl groups of acetone with the chlorine radicals (Cl·), thereby selectively producing more 1,3-dichloroacetone. In the presence of excess chlorine gas, the reaction rate is controlled, and all 1,3-dichloroacetone is converted to 1,1,3-trichloroacetone.

[0027] In particular, by causing chlorination substitution in the micropores of the molecular sieve, the gas-liquid barrier that affects mass transfer is broken through, the reaction efficiency is greatly improved, and the continuous, efficient and stable preparation of 1,1,3-trichloroacetone is achieved. The selectivity of the reaction is improved, the reaction progress is easily controlled, and the 1,1,3-trichloroacetone obtained is high in yield and purity.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention uses a composite catalyst to activate acetone and photocatalyze chlorine to form chlorine radicals (Cl·). In a highly active state, the α-H of acetone is brought into contact with the chlorine radicals (Cl·) to cause a rapid substitution reaction, thereby promoting the simultaneous substitution of the chlorine radicals (Cl·) and the α-H of the two methyl groups of acetone, thereby selectively obtaining more 1,1,3-trichloroacetone.

[0030] 2. The present invention catalyzes the substitution reaction within the micropores of the molecular sieve. The molecular sieve catalyst significantly improves the conversion rate and selectivity of the reaction. The molecular sieve acts as a reaction medium, allowing the reaction liquid and chlorine gas to be adsorbed within the micropores for full contact and rapid substitution reaction. This avoids the gas-liquid barrier in the reactor that affects reaction efficiency and homogeneity in traditional one-pot processes.

[0031] 3. The preparation method of the present invention has high preparation efficiency, high yield and high purity of 1,1,3-trichloroacetone, and easy control of reaction progress parameters, which is suitable for scale-up industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a simplified process flow diagram for preparing trichloroacetone using a molecular sieve photocatalytic reaction. The following diagram shows: 1 - reactor; 2 - vertical reaction tower; 3 - absorption tank; 4 - liquid chlorine storage tank; 5 - ultraviolet light source; 6 - material receiving tank. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0034] Example 1

[0035] As attached Figure 1 The process flow diagram of preparing trichloroacetone by using molecular sieve photocatalytic reaction is as follows: acetone and composite catalyst are premixed and activated in a reactor (1) to obtain a preactivated product; the preactivated product is transported to a vertical reaction tower (2) according to the reaction amount; the vertical reaction tower is equipped with a molecular sieve to adsorb the preactivated product; after the liquid chlorine storage tank (4) is buffered and depressurized, the chlorine is treated with ultraviolet light source (5) and enters the bottom of the tower; the chlorine gradually rises from the bottom of the vertical reaction tower and chlorinates the preactivated product step by step in the micro-pores of the molecular sieve; the hydrogen chloride gas generated by substitution and a small amount of unreacted chlorine are introduced into the absorption tank (3) through the exhaust hole to form a water absorption liquid and fixed discharge; the reaction liquid that meets the standards after the substitution reaction is desorbed by vacuum suction, and the trichloroacetone is collected in the collecting tank (6) at the bottom of the vertical reaction tower.

[0036] The specific implementation plan is:

[0037] S1. 580.8g of acetone and the composite catalyst were added to the reactor in a mass ratio of 100:1.2, the stirring speed was adjusted to 50rpm, and the mixture was stirred and activated for 20min to obtain a pre-activated product; the composite catalyst was a composition of sodium ethoxide, N,N-dimethylacetamide, and triethanolamine pre-formed in a mass ratio of 2:3:5;

[0038] S2. Open the transfer valve and introduce the preactivated product of step S1 into a vertical reaction tower equipped with molecular sieves. The preactivated product is completely adsorbed by the molecular sieves and naturally seeps downward. The vertical reaction tower is provided with one, two, and three temperature-controlled zones from bottom to top. The temperature-controlled zones are controlled by jackets and built-in circulating cooling pipes. The temperature of one section is 10°C, the temperature of the second section is 25°C, and the temperature of the third section is 50°C. The molecular sieve is a titanium silicalite microsphere molecular sieve having a pore size of 6-10 angstroms and a diameter of 1-2 mm.

[0039] After the liquid chlorine storage tank is buffered and depressurized, the chlorine is activated by ultraviolet light. The ultraviolet light source uses a high-pressure mercury lamp to generate ultraviolet light with a wavelength of 404.7nm, an optical power of 1.0kW, and an illumination time of 8 seconds. The ventilation flow rate is 0.22 mol / min and the pressure is controlled at 0.03MPa. The total amount of chlorine ventilation is measured at 2.8 times the molar amount of acetone. The chlorine gradually rises from the bottom of the vertical reaction tower and is chlorinated step by step in the micropores of the molecular sieve and the pre-activated material. The ventilation is completed after about 127 minutes.

[0040] S3. The reaction was continued for 30 minutes. The density of the reaction liquid in each stage was randomly checked. The density of the reaction liquid in the first stage was 1.48 g / mL, the density of the reaction liquid in the second stage was 1.48 g / mL, and the density of the reaction liquid in the third stage was 1.47 g / mL. The density of the reaction liquid met the standard. Vacuum desorption was performed and the product was collected in the receiving tank at the bottom of the vertical reaction tower to obtain 1552 g of 1,1,3-trichloroacetone with a purity of 72.4%, and a yield of 69.6%.

[0041] Example 2

[0042] The specific implementation plan is:

[0043] S1. 580.8g of acetone and the composite catalyst were added to the reactor in a mass ratio of 100:1.5, the stirring speed was adjusted to 50rpm, and the stirring was activated for 20min to obtain a pre-activated material; the composite catalyst was a pre-formed composition of sodium ethoxide, N,N-dimethylacetamide, and triethanolamine in a mass ratio of 2:3:5;

[0044] S2. Open the transfer valve and introduce the preactivated product of step S1 into a vertical reaction tower equipped with molecular sieves. The preactivated product is completely adsorbed by the molecular sieves and naturally seeps downward. The vertical reaction tower is provided with one, two, and three temperature-controlled zones from bottom to top. The temperature-controlled zones are controlled by jackets and built-in circulating cooling pipes. The temperature control section is 5°C, the temperature control section is 20°C, and the temperature control section is 45°C. The molecular sieve is a microsphere zeolite molecular sieve having a pore size of 7-10 angstroms and a diameter of 1-2 mm.

[0045] After the liquid chlorine storage tank is buffered and depressurized, the chlorine is activated by ultraviolet light. The ultraviolet light source uses a high-pressure mercury lamp to generate ultraviolet light with a wavelength of 404.7nm, an optical power of 1.0kW, and an illumination time of 10 seconds. The ventilation flow rate is 0.25 mol / min and the pressure is controlled at 0.05MPa. The total amount of chlorine ventilation is measured at 3.0 times the molar amount of acetone. The chlorine gradually rises from the bottom of the vertical reaction tower and is chlorinated step by step in the micropores of the molecular sieve and the pre-activated material. The ventilation is completed after about 120 minutes.

[0046] S3. The reaction was continued for 60 min. The density of the reaction liquid in each stage was randomly checked. The density of the reaction liquid in the first stage was 1.46 g / mL, the density of the reaction liquid in the second stage was 1.47 g / mL, and the density of the reaction liquid in the third stage was 1.44 g / mL. The density of the reaction liquid met the standard. The reaction liquid was desorbed by vacuum suction and collected in a material receiving tank at the bottom of the vertical reaction tower to obtain 1568 g of 1,1,3-trichloroacetone with a purity of 69.2%, and a yield of 67.2%.

[0047] Comparative Example 1

[0048] The process scheme of Example 1 was adopted, except that no composite catalyst was added to the acetone. 1576 g of 1,1,3-trichloroacetone with a purity of 63.2% was obtained, and the yield was 61.7%.

[0049] Comparative Example 2

[0050] The process scheme of Example 1 was adopted, except that sodium ethoxide was replaced by N,N-dimethylacetamide in the composite catalyst added to acetone. 1580 g of 1,1,3-trichloroacetone with a purity of 66.7% was obtained, and the yield was 65.3%.

[0051] Comparative Example 3

[0052] The process scheme of Example 1 was adopted, except that the molecular sieve was replaced with a large-pore zeolite molecular sieve with a pore size of 50-100 angstroms; 1633 g of 1,1,3-trichloroacetone with a purity of 57.7% was obtained, and the yield was 58.4%.

[0053] Comparative Example 4

[0054] The process scheme of Example 1 was adopted, except that the chlorine gas was not photocatalytically activated, to obtain 1583 g of 1,1,3-trichloroacetone with a purity of 64.0%, with a yield of 62.8%.

[0055] The purity and yield of 1,1,3-trichloroacetone obtained in each embodiment and comparative example are shown in Table 1.

[0056] Table 1:

[0057] Implementation Plan 1,1,3-Trichloroacetone content (%) 1,1,3-Trichloroacetone yield (%) Example 1 72.4 69.6 Example 2 69.2 67.2 Comparative Example 1 63.2 61.7 Comparative Example 2 66.7 65.3 Comparative Example 3 57.7 58.4 Comparative Example 4 64.0 62.8

[0058] The above describes the basic principles, main features, and advantages of the present invention. In particular, molecular sieves with pore sizes close to the size of acetone molecules effectively disperse acetone, increasing the probability of simultaneous replacement of both methyl groups of acetone with chlorine, greatly enhancing the selectivity of 1,1,3-trichloroacetone. As shown in Comparative Example 3, when a large-pore molecular sieve is used, the large pore size limits the dispersion of acetone, significantly reducing the yield of 1,1,3-trichloroacetone and deteriorating the selectivity.

[0059] Those skilled in the art should understand that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements shall fall within the scope of the present invention to be protected.

Claims

1. A method for preparing trichloroacetone by using molecular sieve photocatalytic reaction, characterized in that: It mainly includes the following steps: S1. Acetone and the composite catalyst were added to the reactor in a mass ratio of 100: (1-1.5), the stirring speed was adjusted to 50-80 rpm, and the stirring activation was performed for 15-20 min to obtain a pre-activated product; the composite catalyst was a composition of sodium ethoxide, N, N- dimethylacetamide and triethanolamine; S2. Open the delivery valve and introduce the preactivated material from step S1 into a vertical reaction tower equipped with a molecular sieve. The preactivated material is naturally infiltrated and completely adsorbed by the molecular sieve, wherein the molecular sieve has a pore size of 6-10 angstroms. Chlorine gas activated by ultraviolet light is introduced into the bottom of the vertical reaction tower at a flow rate of 0.20-0.25 mol / min. The total amount of chlorine gas is measured at 2.5-3.0 times the molar amount of acetone in the preactivated material. Chlorine gas gradually rises from the bottom of the vertical reaction tower and chlorinates the preactivated material step by step in the micropores of the molecular sieve. S3. After ventilation is completed, continue the reaction for 0.5-1h. Check the density of the reaction liquid in each section. After it meets the standard, vacuum suction and desorption are performed, and trichloroacetone is collected in the receiving tank at the bottom of the vertical reaction tower.

2. The method for preparing trichloroacetone by using molecular sieve photocatalytic reaction according to claim 1, characterized in that: The composite catalyst is a composition of sodium ethoxide, N,N-dimethylacetamide and triethanolamine in a mass ratio of 2:3:

5.

3. The method for preparing trichloroacetone by using molecular sieve photocatalytic reaction according to claim 1, characterized in that: The molecular sieve is a titanium silicate molecular sieve with a pore size of 6-10 angstroms; the titanium silicate molecular sieve is a microsphere particle with a diameter of 1-2 mm.

4. The method for preparing trichloroacetone by using molecular sieve photocatalytic reaction according to claim 1, characterized in that: An exhaust hole is provided on the upper part of the vertical reaction tower, which is connected to an external negative pressure absorption tank, so that the generated hydrogen chloride gas and a small amount of unreacted chlorine gas are immediately introduced into the absorption tank through the exhaust hole to form water absorption liquid.

5. The method for preparing trichloroacetone by using molecular sieve photocatalytic reaction according to claim 1, characterized in that: The pressure of chlorine gas introduced into the bottom of the vertical reaction tower is controlled at 0.01-0.05 MPa.

6. The method for preparing trichloroacetone by utilizing molecular sieve photocatalytic reaction according to claim 1, wherein: The wavelength of the ultraviolet light source in step S2 is 365-450 nm.

7. The method for preparing trichloroacetone by utilizing molecular sieve photocatalytic reaction according to claim 1, characterized in that: The vertical reaction tower is provided with one, two and three temperature control zones from bottom to top; the temperature of the first section is controlled at 5-15°C, the temperature of the second section is controlled at 20-30°C, and the temperature of the third section is controlled at 45-50°C.

8. The method for preparing trichloroacetone by using molecular sieve photocatalytic reaction according to claim 1, characterized in that: In step S3, the density of the reaction solution is detected, and the standard density of the reaction solution is 1.43-1.48 g / mL.

Images