Preparation method for acetaldehyde and dichloroethane

Abstract

The present invention relates to the technical field of chemical engineering. Disclosed is a preparation method for acetaldehyde and 1,2-dichloroethane. The preparation method of the present invention comprises: using ethylene glycol and hydrogen chloride as reaction raw materials, and under the action of a catalyst, using multiple stages of tank distillation reactors connected in series to perform reaction at a certain pressure and a certain temperature for continuous preparation of acetaldehyde and 1,2-dichloroethane. The method is characterized by using distillation reactors to continuously bring out the generated low-boiling-point acetaldehyde and dichloroethane, and connecting multiple tank distillation reactors in series to enhance the reaction effect, and the method is a novel method for efficiently producing acetaldehyde and 1,2-dichloroethane.

Description

A method for preparing acetaldehyde and ethylene dichloride Technical Field

[0001] The invention belongs to the technical field of chemical industry, and in particular relates to a method for preparing acetaldehyde and dichloroethane. Background Art

[0002] Acetaldehyde has important industrial applications and can be used to manufacture paraacetaldehyde, acetic acid, and synthetic rubber. Traditionally, acetaldehyde is primarily produced by ethylene oxidation. Ethylene dichloride is a key raw material for the production of vinyl chloride monomer, which is primarily used in the production of polyvinyl chloride. Currently, ethylene dichloride is primarily produced by ethylene chlorination. However, my country's petroleum resources are scarce, the price of industrial ethylene is constantly rising, and given my country's abundant coal and limited oil resources, the development of a coal-based method for producing acetaldehyde and ethylene dichloride holds great promise.

[0003] With the rapid development of coal-to-ethylene glycol production, ethylene glycol production is increasing and its price is declining. Therefore, developing downstream products of ethylene glycol and promoting its conversion into higher-value-added chemicals are of practical significance. Ethylene glycol undergoes dehydration in the presence of a strong acid catalyst to produce acetaldehyde. Ethylene glycol undergoes chlorination in the presence of a catalyst with hydrogen chloride to produce 2-chloroethanol and ethylene dichloride. Therefore, the direct and highly selective conversion of ethylene glycol and hydrogen chloride into acetaldehyde and ethylene dichloride is a technical challenge that urgently needs to be addressed in this field.

[0004] Summary of the Invention

[0005] In view of this, the purpose of the present invention is to address the deficiencies in the current technology and provide a method for preparing acetaldehyde and 1,2-dichloroethane using a multi-stage kettle series distillation reaction process; this method can continuously and efficiently catalyze the conversion of ethylene glycol to obtain a higher yield of acetaldehyde and 1,2-dichloroethane.

[0006] In one aspect, the present invention provides a method for preparing acetaldehyde and ethylene dichloride, comprising the following steps: reacting a raw material comprising ethylene glycol and hydrogen chloride with a catalyst in a multi-stage series-continuous distillation reactor to produce acetaldehyde and 1,2-dichloroethane;

[0007] wherein the feed molar ratio of the ethylene glycol to the hydrogen chloride is 1:0.1-4;

[0008] The reaction pressure is 0.1-1 MPa, and the reaction temperature is 150-350°C.

[0009] Optionally, the molar ratio of the ethylene glycol and hydrogen chloride feeds is selected from any value among 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5 and 10.0, or any range therebetween.

[0010] Optionally, the pressure is selected from any value among 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa and 1 MPa, or a range between any two values.

[0011] Optionally, the temperature is selected from any value among 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃ and 350℃, or any range between two of them.

[0012] Optionally, the multi-stage kettle-type series distillation reactor is composed of 2 to 20 kettle-type distillation reactors connected in series.

[0013] Optionally, the number of kettle distillation reactors in the multi-stage kettle series distillation reactor is selected from any value among 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or any range value between two of them.

[0014] Optionally, the series connection is that the discharge port of the previous stage kettle distillation reactor is connected to the feed port of the next stage kettle distillation reactor.

[0015] Optionally, a catalyst is provided in each of the multi-stage series-connected kettle distillation reactors.

[0016] Optionally, the raw materials containing ethylene glycol and hydrogen chloride enter from the feed port of the first end kettle distillation reactor in the multi-stage kettle distillation series reactor, and generate acetaldehyde and 1,2-dichloroethane after multi-stage catalytic reaction, and the acetaldehyde and 1,2-dichloroethane are output from the discharge port of the last end kettle distillation reactor in the multi-stage kettle distillation series reactor.

[0017] That is, the multi-stage kettle-type series distillation reactor includes multiple kettle-type distillation reactors connected in series, and the series connection is such that the discharge port of the previous kettle-type distillation reactor is connected to the feed port of the next kettle-type distillation reactor; each kettle-type distillation reactor is provided with a catalyst; raw materials containing ethylene glycol and hydrogen chloride are introduced into the feed port of the first kettle-type distillation reactor of the multi-stage kettle-type series distillation reactor; and the products acetaldehyde and 1,2-dichloroethane are output from the discharge port of the last kettle-type distillation reactor of the multi-stage kettle-type series distillation reactor.

[0018] Optionally, the kettle distillation reactor includes a reaction chamber, a reflux controller is provided at the upper part of the reaction chamber, and a gas distributor is provided at the lower part of the reaction chamber; a discharge port is provided at the top of the reaction chamber, and a feed port is provided at the bottom of the reaction chamber.

[0019] Optionally, the material of the reaction chamber, the reflux controller or the gas distributor is selected from one of Hastelloy, Monel, graphite lining, glass lining, enamel and polytetrafluoroethylene lining.

[0020] Optionally, the time for the raw materials comprising ethylene glycol and hydrogen chloride to contact and react with the catalyst in the multi-stage series-connected tank distillation reactor is 0.01 to 5 hours.

[0021] The above reaction time of the present invention is the total reaction time.

[0022] Optionally, the contact reaction time is independently selected from any value among 0.01h, 0.05h, 0.1h, 0.2h, 0.5h, 1.0h, 1.2h, 1.5h, 2.0h, 2.5h, 3.0h, 3.5h, 4.0h, 4.5h, 5.0h, or any range therebetween.

[0023] Optionally, the catalyst is a pure liquid phase catalyst system or a liquid-solid phase mixture catalyst system.

[0024] Optionally, the pure liquid phase catalyst system includes at least one of imidazole hydrochloride, pyridine hydrochloride, piperidine hydrochloride, triethylamine hydrochloride, trioctylamine hydrochloride and tetraalkylammonium chloride.

[0025] Optionally, the imidazole hydrochloride is selected from at least one of 1-methylimidazole hydrochloride, 1-ethyl-3-methylimidazole hydrochloride, 1-butyl-3-methylimidazole hydrochloride and 1-hexyl-3-methylimidazole chloride.

[0026] Optionally, the pyridine hydrochloride is selected from at least one of 2-chloromethylpyridine hydrochloride, 1-butylpyridine hydrochloride and 1-butyl-4-methylpyridinium chloride hydrochloride.

[0027] Optionally, the tetraalkylammonium chloride is selected from at least one of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride and tetrabutylammonium chloride.

[0028] Optionally, the liquid-solid mixture catalyst system consists of a liquid catalyst system and a solid porous material.

[0029] Optionally, the solid porous material is selected from one of carbon molecular sieve, mesoporous carbon, activated carbon, porous silica, porous silicon carbide and silicon-aluminum molecular sieve.

[0030] Optionally, the molecular sieve uses all-silicon molecular sieve or high-silicon molecular sieve;

[0031] Preferably, the high silicon molecular sieve is a molecular sieve with SiO2 / Al2O3≥100;

[0032] Optionally, the molecular sieve is at least one selected from MCM-41, SBA-15, silicalite-1, ZSM-5, Beta and mordenite.

[0033] Compared with the prior art, the advantages of this application include:

[0034] 1) The method for preparing dichloroethane using a multi-stage kettle-type serial distillation reaction process provided by the present invention can continuously and efficiently catalyze the conversion of ethylene glycol, and the yields of acetaldehyde and 1,2-dichloroethane are very high.

[0035] 2) The method for preparing acetaldehyde and 1,2-dichloroethane provided in the present invention has great economic benefits. It not only develops downstream products of ethylene glycol, but also is closely connected with the vinyl chloride industry.

[0036] 3) The method for preparing acetaldehyde and ethylene dichloride by a multi-stage series distillation reaction process of the present invention has a smaller capacity of a single reactor in the multi-stage series process when the total reaction volume is the same, making it easier to control mass and heat transfer and more precise reaction control. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic structural diagram of a multi-stage kettle-type series distillation reactor provided in an embodiment of the present invention;

[0038] FIG2 is a schematic structural diagram of a kettle-type distillation reactor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present application will be further described below in conjunction with specific embodiments. The following description is merely a few embodiments of the present application and does not limit the present application in any form. Although the present application discloses the preferred embodiments below, it is not intended to limit the present application. Any person skilled in the art who, without departing from the scope of the technical solution of the present application, makes slight changes or modifications using the above disclosed technical content is equivalent to an equivalent implementation case and falls within the scope of the technical solution.

[0040] Unless otherwise specified, the raw materials in the examples of this application were purchased from commercial channels and used directly without any special treatment.

[0041] The analysis method in the embodiment of the present invention is as follows:

[0042] The conversion of ethylene glycol in the embodiment of the present invention is calculated by the following method:

[0043] The gas chromatographic peak area is obtained by configuring the ethylene glycol content in the standard solution, and the peak area is used as the horizontal axis and the ethylene glycol concentration as the vertical axis to obtain a standard curve; further, the ethylene glycol concentration in the reaction solution after the reaction can be calculated, and the ethylene glycol conversion rate can be calculated based on the concentration.

[0044] In the embodiment of the present invention, the yield of 1,2-dichloroethane is calculated by the following method:

[0045] The gas chromatographic peak area is obtained by configuring the 1,2-dichloroethane content in the standard solution, and the peak area is used as the abscissa and the concentration of 1,2-dichloroethane is used as the ordinate to obtain a standard curve; further, the concentration of 1,2-dichloroethane in the reaction solution after the reaction can be calculated, and the yield of 1,2-dichloroethane can be calculated based on the concentration.

[0046] In the embodiment of the present invention, the yield of acetaldehyde is calculated by the following method:

[0047] The acetaldehyde content in the standard solution is configured to obtain the gas chromatographic peak area, and the peak area is used as the horizontal axis and the acetaldehyde concentration is used as the vertical axis to obtain a standard curve; further, the acetaldehyde concentration in the reaction solution after the reaction can be calculated, and the acetaldehyde yield can be calculated based on the concentration.

[0048] Conversion rate of ethylene glycol (%) = (mass of ethylene glycol after reaction / initial mass of ethylene glycol)*100%.

[0049] Yield of 1,2-dichloroethane (%) = (mass of 1,2-dichloroethane obtained by reaction * 62.06 / 98.96 * initial mass of ethylene glycol) * 100%.

[0050] Yield of acetaldehyde (%) = (mass of acetaldehyde obtained by reaction * 62.06 / 44.05 * initial mass of ethylene glycol) * 100%.

[0051] The gas chromatograph was Agilent 7890.

[0052] Reaction contact time = catalyst mass / mass flow rate of ethylene glycol

[0053] Comparative Example

[0054] 30g of pyridine hydrochloride catalyst was placed in a single-pot distillation reactor. The reactor was heated to 220°C and filled with hydrogen chloride to a pressure of 0.3 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the reactor's inlet at a molar ratio of 1:2. The ethylene glycol mass flow rate was 60g / h, and the reaction contact time with the catalyst was 0.5 hours. The reaction products, acetaldehyde and 1,2-dichloroethane, continuously flowed out of the reactor's outlet in gaseous form. Gas chromatography analysis revealed an ethylene glycol conversion of 72%, an acetaldehyde yield of 33%, and a 1,2-dichloroethane yield of 44%.

[0055] Example 1

[0056] The structure of a multi-stage series-connected kettle distillation reactor is shown in Figures 1 and 2. It comprises multiple series-connected kettle distillation reactors, with the discharge port of the preceding kettle distillation reactor connected to the feed port of the succeeding kettle distillation reactor. Each kettle distillation reactor is equipped with a catalyst. The kettle distillation reactor comprises a reaction chamber, with a reflux controller located in the upper portion and a gas distributor located in the lower portion. The top of the reaction chamber is provided with a discharge port, and the bottom of the reaction chamber is provided with a feed port. Ethylene glycol and hydrogen chloride feed gases are introduced into the feed port of the first kettle distillation reactor in the multi-stage series-connected kettle distillation reactor. The reaction products, acetaldehyde and 1,2-dichloroethane, are discharged from the discharge port of the last kettle distillation reactor in the multi-stage series-connected kettle distillation reactor.

[0057] 150g of pyridine hydrochloride catalyst was evenly distributed across five series-connected reactors. The reactors were heated to 220°C and filled with hydrogen chloride to a pressure of 0.3 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the inlet of the first reactor in the series of five reactors at a molar ratio of 1:2. The ethylene glycol mass flow rate was 300g / h, and the reaction contact time with the catalyst was 0.5 hours. The reaction products, acetaldehyde and 1,2-dichloroethane, were continuously discharged in gaseous form from the outlet of the last reactor in the series. Gas chromatography analysis revealed an ethylene glycol conversion of 99%, an acetaldehyde yield of 29%, and a 1,2-dichloroethane yield of 70%.

[0058] Example 2

[0059] 600g of triethylamine hydrochloride catalyst was evenly distributed across 20 series-connected reactors. The reactors were heated to 150°C and filled with hydrogen chloride to a pressure of 1 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the inlet of the first reactor in the series at a molar ratio of 1:4. The ethylene glycol mass flow rate was 120g / h, and the reaction contact time with the catalyst was 5 hours. The reaction products, acetaldehyde and 1,2-dichloroethane, continuously flowed out of the outlet of the last reactor in the series as gaseous products. Gas chromatography analysis revealed an ethylene glycol conversion of 100%, an acetaldehyde yield of 15%, and a 1,2-dichloroethane yield of 85%.

[0060] Example 3

[0061] 120g of piperidine hydrochloride and 120g of activated carbon catalyst were evenly distributed in eight series-connected reactor distillation reactors. The reactors were heated to 350°C and filled with hydrogen chloride to a pressure of 0.5 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the inlet of the first reactor in the series at a molar ratio of 1:0.1. The ethylene glycol mass flow rate was 24 kg / h, and the reaction contact time with the catalyst was 0.01 hour. The reaction products, acetaldehyde and 1,2-dichloroethane, were continuously discharged in gaseous form from the outlet of the last reactor in the series. Gas chromatography analysis revealed an ethylene glycol conversion of 90%, an acetaldehyde yield of 63%, and a 1,2-dichloroethane yield of 25%.

[0062] Example 4

[0063] 300g of 1-butyl-3-methylimidazole hydrochloride and 150g of a strongly acidic cation exchange resin catalyst were evenly distributed in fifteen series of autoclave distillation reactors. The reactors were heated to 200°C and filled with hydrogen chloride to a pressure of 0.1 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the inlet of the first reactor in the series of autoclave distillation reactors at a molar ratio of 1:1. The ethylene glycol mass flow rate was 450g / h, and the reaction contact time with the catalyst was 1 hour. The reaction products, acetaldehyde and 1,2-dichloroethane, were continuously discharged in gaseous form from the outlet of the last reactor in the series of autoclave distillation reactors. Gas chromatography analysis revealed an ethylene glycol conversion of 100%, an acetaldehyde yield of 45%, and a 1,2-dichloroethane yield of 55%.

[0064] Example 5

[0065] 55g of trioctylamine hydrochloride and 5g of ZSM-5 molecular sieve catalyst were evenly distributed in two series-connected batch distillation reactors. The reactors were heated to 300°C and filled with hydrogen chloride to a pressure of 0.7 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the inlet of the first reactor in the series at a molar ratio of 1:0.5. The ethylene glycol mass flow rate was 600g / h, and the reaction contact time with the catalyst was 0.1 hour. The reaction products, acetaldehyde and 1,2-dichloroethane, were continuously discharged in gaseous form from the outlet of the last reactor in the series. Gas chromatography analysis revealed an ethylene glycol conversion of 94%, an acetaldehyde yield of 53%, and a 1,2-dichloroethane yield of 38%.

[0066] Example 6

[0067] 250g of 1-ethyl-3-methylimidazole hydrochloride and 50g of a porous silica catalyst were evenly distributed in a series of ten autoclave distillation reactors. The reactors were heated to 250°C and filled with hydrogen chloride to a pressure of 0.2 MPa. Ethylene glycol and hydrogen chloride gas were continuously introduced into the inlet of the first reactor in the series of autoclave distillation reactors at a molar ratio of 1:3. The ethylene glycol mass flow rate was 150g / h, and the reaction contact time with the catalyst was 2 hours. The reaction products, acetaldehyde and 1,2-dichloroethane, were continuously discharged in gaseous form from the outlet of the last reactor in the series of autoclave distillation reactors. Gas chromatography analysis revealed an ethylene glycol conversion of 100%, an acetaldehyde yield of 23%, and a 1,2-dichloroethane yield of 77%.

[0068] The reaction results of Example 1 and the comparative example show that:

[0069] Under the same reaction conditions, the comparative example, using a single-stage still distillation reactor, achieved an ethylene glycol conversion of 72%, an acetaldehyde yield of 33%, and a 1,2-dichloroethane yield of 44%. In Example 1 of the present invention, using a five-stage series still distillation reactor, the ethylene glycol conversion was 99%, the acetaldehyde yield was 29%, and the 1,2-dichloroethane yield was 70%. Clearly, the use of the multi-stage series distillation reactor in Example 1 of the present invention increased the ethylene glycol conversion from 72% to 99%, and the 1,2-dichloroethane yield from 44% to 70%.

[0070] In Example 2 of the present invention, after using 20 stages of serial distillation reactors, the ethylene glycol conversion rate was 100%, the acetaldehyde yield was 15%, and the 1,2-dichloroethane yield was 85%.

[0071] In Example 3 of the present invention, after using 8-stage series distillation reactors, the ethylene glycol conversion rate was 90%, the acetaldehyde yield was 63%, and the 1,2-dichloroethane yield was 25%.

[0072] In Example 4 of the present invention, after using 15 stages of serial distillation reactors, the ethylene glycol conversion rate was 100%, the acetaldehyde yield was 45%, and the 1,2-dichloroethane yield was 55%.

[0073] In Example 5 of the present invention, after using two-stage series distillation reactors, the ethylene glycol conversion rate was 94%, the acetaldehyde yield was 53%, and the 1,2-dichloroethane yield was 38%.

[0074] In Example 6 of the present invention, after using 10 stages of series-connected distillation reactors, the ethylene glycol conversion rate was 100%, the acetaldehyde yield was 23%, and the 1,2-dichloroethane yield was 77%.

[0075] From the above experiments, it can be seen that the present invention can improve the ethylene glycol conversion rate and product yield by using 2 to 20 stages of series distillation reactors compared with a single-stage distillation reactor.

[0076] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing acetaldehyde and ethylene dichloride, characterized in that: The following steps are involved: The raw materials including ethylene glycol and hydrogen chloride are contacted with a catalyst in a multi-stage tank series distillation reactor to react and generate acetaldehyde and 1,2-dichloroethane; Wherein, the feed molar ratio of the ethylene glycol to the hydrogen chloride is 1:0.1-4; The reaction pressure is 0.1-1 MPa, and the reaction temperature is 150-350°C.

2. A method for preparing acetaldehyde and ethylene dichloride according to claim 1, characterized in that: The multi-stage kettle-type series distillation reactor is composed of 2 to 20 kettle-type distillation reactors connected in series.

3. A method for preparing acetaldehyde and ethylene dichloride according to claim 2, characterized in that: The series connection is that the discharge port of the previous stage kettle distillation reactor is connected with the feed port of the next stage kettle distillation reactor.

4. A method for preparing acetaldehyde and ethylene dichloride according to claim 2, characterized in that: Each of the multi-stage tank-type series distillation reactors is provided with a catalyst.

5. A method for preparing acetaldehyde and ethylene dichloride according to claim 1, characterized in that: The raw materials containing ethylene glycol and hydrogen chloride enter from the feed port of the first end tank distillation reactor in the multi-stage tank distillation series reactor, and generate acetaldehyde and 1,2-dichloroethane after multi-stage catalytic reaction. The acetaldehyde and 1,2-dichloroethane are output from the discharge port of the last end tank distillation reactor in the multi-stage tank distillation series reactor.

6. A method for preparing acetaldehyde and ethylene dichloride according to claim 2, characterized in that: The kettle distillation reactor comprises a reaction chamber, a reflux controller is arranged at the upper part of the reaction chamber, a gas distributor is arranged at the lower part of the reaction chamber; a discharge port is arranged at the top of the reaction chamber, and a feed port is arranged at the bottom of the reaction chamber.

7. A method for preparing acetaldehyde and ethylene dichloride according to claim 6, characterized in that: The material of the reaction chamber, the reflux controller or the gas distributor is selected from one of Hastelloy, Monel, graphite lining, glass lining, enamel and polytetrafluoroethylene lining.

8. A method for preparing acetaldehyde and ethylene dichloride according to claim 1, characterized in that: The time for the raw material containing ethylene glycol and hydrogen chloride to contact and react with the catalyst in the multi-stage tank-type series distillation reactor is 0.01 to 5 hours.

9. A method for preparing acetaldehyde and ethylene dichloride according to claim 1, characterized in that: The catalyst is a pure liquid phase catalyst system or a liquid-solid phase mixture catalyst system.

10. A method for preparing acetaldehyde and ethylene dichloride according to claim 9, characterized in that: The pure liquid phase catalyst system comprises at least one of imidazole hydrochloride, pyridine hydrochloride, piperidine hydrochloride, triethylamine hydrochloride, trioctylamine hydrochloride and tetraalkylammonium chloride.

11. A method for preparing acetaldehyde and ethylene dichloride according to claim 10, characterized in that: The imidazole hydrochloride is selected from at least one of 1-methylimidazole hydrochloride, 1-ethyl-3-methylimidazole hydrochloride, 1-butyl-3-methylimidazole hydrochloride and 1-hexyl-3-methylimidazole chloride.

12. A method for preparing acetaldehyde and ethylene dichloride according to claim 10, characterized in that: The pyridine hydrochloride is selected from at least one of 2-chloromethylpyridine hydrochloride, 1-butylpyridine hydrochloride and 1-butyl-4-methylpyridinium chloride hydrochloride.

13. A method for preparing acetaldehyde and ethylene dichloride according to claim 10, characterized in that: The tetraalkylammonium chloride is selected from at least one of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride and tetrabutylammonium chloride.

14. A method for preparing acetaldehyde and ethylene dichloride according to claim 9, characterized in that: The liquid-solid phase mixture catalyst system consists of a liquid phase catalyst system and a solid porous material.

15. A method for preparing acetaldehyde and ethylene dichloride according to claim 14, characterized in that: The solid porous material is selected from one of carbon molecular sieve, mesoporous carbon, activated carbon, porous silica, porous silicon carbide and silicon-aluminum molecular sieve.

16. A method for preparing acetaldehyde and ethylene dichloride according to claim 15, characterized in that: The molecular sieve uses all-silicon molecular sieve or high-silicon molecular sieve.

17. A method for preparing acetaldehyde and ethylene dichloride according to claim 16, characterized in that: The high-silicon molecular sieve is a molecular sieve with SiO2 / Al2O3≥100.

18. A method for preparing acetaldehyde and ethylene dichloride according to claim 15, characterized in that: The molecular sieve is at least one selected from MCM-41, SBA-15, silicalite-1, ZSM-5, Beta and mordenite.

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