Composite catalyst for preparing deuterated chloroform and preparation method thereof

Abstract

The invention relates to the field of catalysts, aims to solve the problems of low yield and low deuteration degree of existing catalysts, and provides a preparation method of a composite catalyst for preparing deuterated chloroform, and the preparation method comprises the following steps: S100, taking a molecular sieve-alumina-zinc oxide catalyst, dropwise adding a carbazole ethanol solution into the molecular sieve-alumina-zinc oxide catalyst, then dropwise adding N, N-dimethyl formamide, and carrying out a reaction for 2-4 hours; dissolving with an N, N-dimethylformamide solution to obtain a pre-reaction solution; s200, heating, crystallizing, filtering and drying the pre-reaction solution to obtain a dried product; and S300, obtaining the composite catalyst from the dried product under the induction of an electric field and a magnetic field. According to the invention, the selectivity and conversion efficiency of the molecular sieve, aluminum oxide and zinc oxide as catalysts are utilized, and the carbazole ethanol solution is combined, so that hydroxyl in carbazole ethanol can be partially condensed with residual oxyhydrogen bonds in the molecular sieve, aluminum oxide and zinc oxide except hydrogen bonds at a relatively high temperature to form firm chemical bonds; therefore, the deuteration degree, the purity and the yield of the deuterated chloroform are improved.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more specifically, to a composite catalyst for preparing deuterated chloroform and a method thereof. Background Technology

[0002] Deuterated reagents are essential chemical reagents in nuclear magnetic resonance (NMR) testing, with deuterated chloroform being the most widely used. Currently, the main method for preparing deuterated chloroform is the reaction of trichlorocarbonyl derivatives with heavy water under an alkaline catalyst. The literature (Preparation of Deuterated Solvents for Nuclear Magnetic Resonance Spectrometry. Analytical Chemistry, 1963, 35(10), 1560-1560) reports the synthesis of deuterated chloroform by reacting hexachloroacetone with heavy water under the catalyst of pyridine. However, experiments have revealed certain problems with this method using pyridine as a catalyst: 1) the degree of deuteration of the produced deuterated chloroform is not high, typically around 95%; 2) the reaction yield is not high, typically around 50-60%. 3) After the reaction is complete, chloroform needs to be distilled out, and some pyridine will also be distilled out at the same time, resulting in pyridine being mixed in with chloroform. Further separation and purification are required, which further reduces the yield. Summary of the Invention

[0003] The purpose of this invention is to provide a composite catalyst for preparing deuterated chloroform and its preparation method, thereby solving the problem of low yield and deuteration degree of existing catalysts when used to prepare deuterated chloroform.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A method for preparing a composite catalyst for deuterated chloroform includes the following steps:

[0006] S100. Take a molecular sieve-alumina-zinc oxide catalyst and add carbazole ethanol solution dropwise to it to obtain a pre-reaction solution;

[0007] S200. The pre-reaction solution is filtered and dried to obtain a dried product.

[0008] S300. The dried product is subjected to an electric field and a magnetic field to obtain a composite catalyst.

[0009] Vacuum drying can be used for the drying process.

[0010] Preferably, the molar ratio of the molecular sieve-alumina-zinc oxide catalyst to carbazole ethanol is 1:(1-2).

[0011] Preferably, the drying process is carried out at a temperature of 100-120°C for 7-9 hours.

[0012] Preferably, after the drying process in S200, a dried product is obtained, and then the dried product is sequentially subjected to hydraulic pressing and pulverization to obtain a 40-60 mesh dried product; the pressure of hydraulic pressing is 8-12 MPa, and the hydraulic time is 2-4 min.

[0013] Preferably, the solvent used in the reaction systems of S100 and S200 is heavy water.

[0014] Because the hydroxyl groups in water molecules can form strong hydrogen bonds with substances such as molecular sieves, they cannot be completely removed even after repeated washing. Therefore, this invention uses heavy water.

[0015] Preferably, S300 includes:

[0016] A100, the preproduct is calcined after being induced by an electric field to obtain the initial induced product;

[0017] A200. The initial induced product is calcined after magnetic field induction to obtain a composite catalyst.

[0018] Electric field induction can orient molecules, then calcination enhances the interaction between the carrier and the active component, followed by magnetic field induction using an electromagnet to promote ordered assembly, and finally calcination forms a magnetically responsive structure.

[0019] Preferably, the voltage induced by the electric field is 1-10 kV / cm, and the induction time is 1.8-2.4 h.

[0020] Preferably, the field strength induced by the magnetic field is 45-55T, and the induction time is 2-3h.

[0021] Preferably, the calcination temperature of A100 is 400-550℃ and the calcination time is 1.5-3h; the calcination temperature of A200 is 400-550℃ and the calcination time is 1.5-3h.

[0022] A composite catalyst prepared by the method described above.

[0023] The present invention has at least the following beneficial effects:

[0024] This invention utilizes the selectivity and conversion efficiency of molecular sieves, alumina, and zinc oxide as catalysts. Combined with carbazole ethanol solution, at higher temperatures, in addition to hydrogen bonding, the hydroxyl groups in carbazole ethanol can partially condense with the residual hydroxyl bonds in the molecular sieves, alumina, and zinc oxide to form relatively strong chemical bonds, exhibiting polarization effects. This improves the deuteration degree, purity, and yield of deuterated chloroform. Applying the composite catalyst provided by this invention to the preparation of deuterated chloroform overcomes the shortcomings of using pyridine, calcium oxide, anhydrous sodium carbonate, etc. as catalysts, and can produce deuterated chloroform with high deuteration degree, high purity, and high yield. Detailed Implementation

[0025] To make the objectives, methods, and advantages of the embodiments of the present invention clearer, the methods in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0026] Example 1: A method for preparing a composite catalyst for deuterated chloroform, comprising the following steps:

[0027] S100. Take the molecular sieve-alumina-zinc oxide catalyst and add carbazole ethanol solution dropwise while stirring. After the addition is complete, sonicate and disperse for 30 minutes to obtain the pre-reaction solution.

[0028] The molar ratio of the molecular sieve-alumina-zinc oxide catalyst to carbazole ethanol is 1:1;

[0029] S200. The pre-reaction solution undergoes a filtration process: the precipitate is filtered and washed using a circulating water multi-purpose vacuum pump until the filtrate is neutral. The precipitate obtained by filtration is then dried to obtain a dried product. The dried product is then sequentially subjected to hydraulic pressing and pulverization to obtain a 40-mesh dried product. The hydraulic pressing pressure is 8 MPa, and the hydraulic time is 2 min. The temperature of the drying process is 100℃, and the drying time is 7 h.

[0030] S300. The dried product is subjected to an electric field and a magnetic field to obtain a composite catalyst.

[0031] The S300 includes:

[0032] A100 and the pre-product were induced by an electric field using parallel plate electrodes and then calcined to obtain the initial induced product; the voltage for electric field induction was 1 kV / cm, the induction time was 1.8 h, the calcination temperature was 400 ℃, and the calcination time was 1.5 h.

[0033] A200. The initial induced product is calcined after being induced by an electromagnet using a magnetic field to obtain a composite catalyst. The magnetic field strength is 45T and the induction time is 2h. The calcination temperature is 400℃ and the calcination time is 1.5h.

[0034] Heavy water is used as the solvent in both the reaction systems of S100 and S200.

[0035] Example 2: A method for preparing a composite catalyst for deuterated chloroform, comprising the following steps:

[0036] S100. Take the molecular sieve-alumina-zinc oxide catalyst and add carbazole ethanol solution dropwise while stirring. After the addition is complete, sonicate and disperse for 30 minutes to obtain the pre-reaction solution.

[0037] The molar ratio of the molecular sieve-alumina-zinc oxide catalyst to carbazole ethanol is 1:2;

[0038] S200. The pre-reaction solution undergoes a filtration process: the precipitate is filtered and washed using a circulating water multi-purpose vacuum pump until the filtrate is neutral. The precipitate obtained by filtration is then dried to obtain a dried product. The dried product is then sequentially subjected to hydraulic pressing and pulverization to obtain a 60-mesh dried product. The hydraulic pressing pressure is 12 MPa, and the hydraulic time is 4 min. The temperature of the drying process is 120℃, and the drying time is 9 h.

[0039] S300. The dried product is subjected to an electric field and a magnetic field to obtain a composite catalyst.

[0040] The S300 includes:

[0041] A100 and the pre-product were induced by an electric field using parallel plate electrodes and then calcined to obtain the initial induced product; the voltage for electric field induction was 10 kV / cm, the induction time was 2.4 h, the calcination temperature was 550 ℃, and the calcination time was 3 h.

[0042] A200. The initial induced product is induced by a magnetic field using an electromagnet and then calcined to obtain a composite catalyst. The magnetic field strength is 55T and the induction time is 3h. The calcination temperature is 550℃ and the calcination time is 3h.

[0043] Heavy water is used as the solvent in both the reaction systems of S100 and S200.

[0044] Example 3: A method for preparing a composite catalyst for deuterated chloroform, comprising the following steps:

[0045] S100. Take the molecular sieve-alumina-zinc oxide catalyst and add carbazole ethanol solution dropwise while stirring. After the addition is complete, sonicate and disperse for 30 minutes to obtain the pre-reaction solution.

[0046] The molar ratio of the molecular sieve-alumina-zinc oxide catalyst to carbazole ethanol is 1:1;

[0047] S200, the pre-reaction solution undergoes a filtration process: the precipitate is filtered and washed using a circulating water multi-purpose vacuum pump until the filtrate is neutral. The precipitate obtained by filtration is then dried to obtain a dried product. The dried product is then sequentially subjected to hydraulic pressing and pulverization to obtain a 50-mesh dried product. The hydraulic pressing pressure is 10 MPa, and the hydraulic time is 3 min. The temperature of the drying process is 110℃, and the drying time is 8 h.

[0048] S300. The dried product is subjected to an electric field and a magnetic field to obtain a composite catalyst.

[0049] The S300 includes:

[0050] A100, the pre-product was induced by an electric field using parallel plate electrodes, and then calcined to obtain the initial induced product; the voltage for electric field induction was 8 kV / cm, the induction time was 2 h; the calcination temperature was 400℃, and the calcination time was 2 h.

[0051] A200. The initial induced product is induced by an electromagnet and then calcined to obtain a composite catalyst. The field strength of the magnetic field is 50T and the induction time is 2h. The calcination temperature is 400℃ and the calcination time is 2h.

[0052] Heavy water is used as the solvent in both the reaction systems of S100 and S200.

[0053] The preparation methods of the molecular sieve-alumina-zinc oxide catalysts in Examples 1-3 include:

[0054] Preparation of alumina-zinc oxide: A 1 mol / L sodium carbonate solution and a 1 mol / L nitrate mixture were added separately to 250 ml separatory funnels, then dropped into a three-necked flask in a constant-temperature water bath. Precipitation was carried out while stirring, maintaining a precipitation temperature of 70℃ and a pH of 7. After the solution was added, stirring continued for 20 min. The precipitate was then poured into a beaker and aged at room temperature for 10 h. After aging, the precipitate was filtered and washed using a circulating water vacuum pump until the filtrate was neutral. The filtered precipitate was then placed in an electric constant-temperature drying oven at 110℃ for 8 h. Finally, it was placed in a muffle furnace, heated from room temperature (20℃) to 400℃, and calcined at 400℃ for 4 h. After cooling to room temperature, the sample was compressed into tablets, pulverized using a powder pulverizer, and then sieved to obtain particles of 40–60 mesh.

[0055] Preparation of molecular sieve-alumina-zinc oxide: 1.2g of molecular sieve powder and 0.4g of the prepared alumina-zinc oxide powder were mixed at a mass ratio of 3:1, further mixed and ground in a mortar to obtain a 100-200 mesh powder. The powder was then transferred to a mold and compressed into sheets using a rocker press at 10MPa for 3 minutes. The compressed powder was ground again to disperse it into fine particles, and collected by sieving through a 30-50 mesh sieve to obtain blended particles. The blended particles were placed in a muffle furnace, heated from room temperature (20℃) to 550℃, calcined at 550℃ for 6 hours, and then cooled to room temperature. The sample was then pressed into tablets, pulverized using a powder pulverizer, and the 40-60 mesh blended particles were screened out for use as a molecular sieve-alumina-zinc oxide catalyst.

[0056] Application example: 36.54 g (25.4 ml, 0.138 mol) of hexachloroacetone and 3.71 g (0.025 mol) of composite catalyst (molecular sieve-alumina-zinc oxide-carbazole ethanol) prepared according to the preparation method provided in Example 3 were added to a 250 ml two-necked flask equipped with a water separator, reflux condenser and drying tube. While stirring, 5.53 g (5 ml, 0.276 mol) of heavy water was added dropwise. The reaction was carried out at 60 °C for 4 h, and then the temperature was raised to 90 °C. The reflux fraction was collected to obtain 20 g of colorless and transparent liquid.

[0057] The reaction yield was 95%, and the degree of deuteration was 99.80% (the degree of deuteration was consistent with that of heavy water, which was 99.8%).

[0058] Comparative Example 1: Preparation of deuterated chloroform under the action of a conventional catalyst, as detailed below:

[0059] According to the reference (Preparation of Deuterated Solvents for Nuclear Magnetic Resonance Spectrometry. Analytical Chemistry, 1963, 35(10), 1560-1560): 36.54 g (25.4 ml, 0.138 mol) of hexachloroacetone and 1.97 g (2 ml, 0.025 mol) of pyridine were added to a 250 ml two-necked flask equipped with a water separator, reflux condenser and drying tube. While stirring, 5.53 g (5 ml, 0.276 mol) of heavy water was added dropwise. The reaction was carried out at 60 °C for 4 h, and then the temperature was raised to 90 °C. The reflux fraction was collected to obtain 15 g of colorless and transparent liquid.

[0060] The reaction yield was 85%, and the degree of deuteration was 98.64% (99.8% for heavy water).

[0061] Comparative Example 2: The difference from the application example is that the preparation method of the composite catalyst does not include the S300 step.

[0062] The reaction yield was 85%, and the degree of deuteration was 98.70% (99.8% for heavy water).

[0063] Comparative Example 3: Preparation of deuterated chloroform under the action of carbazole ethanol catalyst, as detailed below:

[0064] 36.54 g (25.4 ml, 0.138 mol) of hexachloroacetone and 5.33 g (0.025 mol) of carbazole ethanol were added to a 250 ml two-necked flask equipped with a water separator, reflux condenser and drying tube. While stirring, 5.53 g (5 ml, 0.276 mol) of heavy water was added dropwise. The mixture was reacted at 60 °C for 4 h, and then the temperature was raised to 90 °C. The reflux fraction was collected to obtain 10 g of colorless and transparent liquid.

[0065] The reaction yield was 70%, and the degree of deuteration was 98.86% (99.8% for heavy water).

[0066] In summary, this invention uses inexpensive molecular sieves, sodium carbonate, aluminum nitrate, zinc nitrate, and carbazole ethanol as raw materials. The reaction is carried out under vacuum at 400°C, and a molecular sieve-alumina-zinc oxide-carbazole ethanol composite catalyst is obtained through precipitation, aging, molding, drying, and calcination. Applying this composite catalyst to the preparation of deuterated chloroform avoids the shortcomings of traditional pyridine catalysts. It has the following advantages: (1) The deuterated chloroform obtained has a high degree of deuteration, reaching 99.8%, meeting the requirements of NMR reagents; (2) The yield of the synthesis reaction is significantly increased, exceeding 90%, further saving raw materials and reducing production costs; (3) The deuterated chloroform product is very pure after distillation from the reactor, with no catalyst residue; (4) The catalyst preparation is simple, the raw materials are inexpensive, and it is suitable for industrial use.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite catalyst for preparing deuterated chloroform, characterized in that, Includes the following steps: S100. Take a molecular sieve-alumina-zinc oxide catalyst and add carbazole ethanol solution dropwise to it to obtain a pre-reaction solution; S200. The pre-reaction solution is filtered and dried to obtain a dried product. S300. The dried product is subjected to an electric field and a magnetic field to obtain a composite catalyst.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the molecular sieve-alumina-zinc oxide catalyst to carbazole ethanol is 1:(1-2).

3. The preparation method according to claim 1, characterized in that, The drying process is carried out at a temperature of 100-120℃ for 7-9 hours.

4. The preparation method according to claim 1, characterized in that, After the drying process in S200, a dried product is obtained. The dried product is then subjected to hydraulic pressing and pulverization in sequence to obtain a 40-60 mesh dried product. The pressure of the hydraulic pressing is 8-12 MPa, and the hydraulic time is 2-4 min.

5. The preparation method according to claim 1, characterized in that, Heavy water is used as the solvent in both the reaction systems of S100 and S200.

6. The preparation method according to any one of claims 1-5, characterized in that, The S300 includes: A100, the preproduct is calcined after being induced by an electric field to obtain the initial induced product; A200. The initial induced product is calcined after magnetic field induction to obtain a composite catalyst.

7. The preparation method according to claim 6, characterized in that, The voltage induced by the electric field is 1-10 kV / cm, and the induction time is 1.8-2.4 h.

8. The preparation method according to claim 6, characterized in that, The field strength induced by the magnetic field is 45-55T, and the induction time is 2-3h.

9. The preparation method according to claim 6, characterized in that, The A100 is calcined at a temperature of 400-550℃ for 1.5-3 hours; the A200 is calcined at a temperature of 400-550℃ for 1.5-3 hours.

10. A composite catalyst prepared by the method according to any one of claims 1-9.