Preparation method and application of catalyst for catalyzing deuterated methanol to directly synthesize deuterated dimethyl carbonate
By using the catalyst with the use of cymbal and iron salt as the main ingredient, through water and thermal synthesis technology, the problem of low catalytic efficiency of 氘 and carbon dioxide directly synthetic carbonate glycolic glycolin in existing technologies has achieved low catalytic efficiency of carbonate. The catalytic effect of sexual and high yield rates, and the stability of the catalyst is better.
Patent Information
- Application Number
- CN202410962610.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-18
- Publication Date
- 2025-01-21
AI Technical Summary
The prior art is difficult to efficiently catalyze the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate, and the activity, selectivity and stability of the catalyst are insufficient.
A catalyst with cerium and iron salt as the main components is used, and a catalyst with high activity and selectivity is formed through the mixing, post-treatment and hydrothermal synthesis of cerium solution and iron solution. The catalyst has good catalytic performance at lower temperatures and pressures.
A catalytic reactions with high selectivity and high yield rates have been achieved. The catalyst has almost no activity decreased in cycle use, the selectivity is maintained at more than 99%, and the stability is better.
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Figure CN119327467A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a preparation method and application of a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate. Background Art
[0002] Deuterated compounds are often used as solvents in nuclear magnetic resonance detection. Due to the difference in spin quantum numbers, deuterated compounds can be used as solvents in nuclear magnetic resonance hydrogen spectrum detection, which will not interfere with the detection of 1H, can avoid background interference caused by solvent H atoms, and improve the resolution and signal-to-noise ratio of NMR spectra. Deuterated compounds can also be used to explore reaction mechanisms. Since chemical bonds formed by D in molecules are usually more stable than chemical bonds formed by H, deuterium replaces certain specific CH bonds and compares the reaction rates before and after the replacement, that is, the KIE value, to determine whether the CH bond breakage is the rate-determining step. By replacing the reagents in the reaction with deuterated reagents, hydrogen bond formation, dissociation, and other processes that interact or are related to the solvent can be explored. In addition, deuterated compounds are often used as markers or tracers to track the transformation process of compounds in chemical reactions or biological processes. By introducing deuterated compounds into the compounds to be analyzed, their behavior and transformation pathways in the reaction can be tracked, so as to study reaction kinetics, metabolic pathways, etc., and further understand the reaction mechanism. By detecting whether there are unlabeled compounds and substrates labeled with four D atoms after the reaction, it is determined whether a ring-closing reaction and a double decomposition reaction occur.
[0003] With the increasing application of deuterated compounds in medicinal chemistry, analytical chemistry and materials science, exploring the synthesis strategies of deuterated compounds has become one of the current research hotspots. Summary of the invention
[0004] The present invention aims to provide a preparation method and application of a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate. The catalytic reaction of the present invention has a high yield and high selectivity.
[0005] The technical solution adopted by the present invention is as follows:
[0006] A method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate comprises the following steps:
[0007] 1) Preparation of cerium solution: dissolving cerium salt in deionized water to obtain a cerium solution;
[0008] 2) Preparation of iron solution: dissolving iron salt in deionized water, then adding sodium salt to the solution for post-treatment, and stirring well to obtain an iron solution;
[0009] 3) slowly adding the iron solution of step 2) dropwise to the cerium solution of step 1) under stirring, and continuing stirring;
[0010] 4) adding alkali to the mixed solution stirred evenly in step 3) to adjust the pH to >10 (the purpose of adjustment is to completely precipitate Ce and Fe ions and adjust the solution environment to a strong alkaline state), and heating and stirring;
[0011] 5) After the stirring is completed, the mixed solution is transferred to a hydrothermal synthesis reactor with a polytetrafluoroethylene liner, and the hydrothermal synthesis reactor is sealed and transferred to an oven for hydrothermal treatment;
[0012] 6) After the hydrothermal treatment, the solution is cooled to room temperature, centrifuged, washed, dried, calcined in a mixture of hydrogen and argon, and finally ground to obtain the target catalyst.
[0013] Furthermore, the cerium salt in step 1) is one or more of cerium chloride, cerium nitrate, cerium sulfate, and ammonium cerium nitrate, preferably cerium nitrate.
[0014] Furthermore, the iron salt in step 2) is one or more of ferric chloride, ferric nitrate, and ferric sulfate, preferably ferric chloride; the molar ratio of the iron salt to the cerium salt is 1:5-20, preferably 1:8-10.
[0015] Furthermore, the sodium salt in step 2) is one or more of sodium chloride, sodium dihydrogen phosphate, sodium sulfate, sodium formate, and sodium tungstate, preferably a mixture of sodium dihydrogen phosphate and sodium sulfate, and the molar ratio of sodium dihydrogen phosphate to sodium sulfate is 2-5:1, preferably 3.5-4:1; the molar ratio of the sodium salt to the cerium salt is 1:10-50, preferably 1:20-24.
[0016] Furthermore, in step 4), the heating temperature is 50-80° C., preferably 60° C., and the heating time is 20-40 min.
[0017] Furthermore, in step 5), the temperature of the hydrothermal treatment is 160-200° C., preferably 180-185° C., and the time of the hydrothermal treatment is 12-20 hours, preferably 16-18 hours.
[0018] Furthermore, in step 6), the volume flow ratio of hydrogen to argon is 1:2-4, preferably 1:3, and the calcination procedure is: after uniformly heating from room temperature to a constant temperature calcination temperature, the constant temperature is maintained for a period of time, the heating rate is 1-5°C / min, preferably 2°C / min, the constant temperature calcination temperature is 400-600°C, preferably 500°C, and the constant temperature calcination time is 3-6h.
[0019] The present invention also provides an application of the catalyst in the reaction of catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate, wherein the reaction raw materials include deuterated methanol and carbon dioxide gas, and specifically, the catalyst is placed in a stainless steel autoclave reactor, deuterated methanol is added, carbon dioxide is introduced for stirring reaction, and the deuterated methanol is converted into deuterated dimethyl carbonate. The reaction temperature is 130-150° C., the carbon dioxide pressure is 3.0-5.0 MPa, the stirring rate is 300-600 r / min, and the reaction time is 4-8 hours.
[0020] The beneficial effects of the present invention are as follows: the catalyst provided by the present invention has good activity at relatively low temperature and relatively low pressure, can realize high-selectivity catalytic direct esterification of deuterated methanol to synthesize deuterated dimethyl carbonate, the catalyst can be separated and recovered, the yield and selectivity are relatively high, and the stability is also good. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 is a SEM image of the catalyst of Example 1 of the present invention.
[0022] Figure 2 This is a TEM image of the catalyst of Example 1 of the present invention.
[0023] Figure 3 It is the N2 adsorption isotherm of the catalyst in Example 1 of the present invention at -196°C and the corresponding pore size distribution diagram. DETAILED DESCRIPTION
[0024] The technical solution of the present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.
[0025] Example 1
[0026] Weigh 8.68 g of cerium nitrate hexahydrate crystals (20 mmol) and dissolve them in 30 ml of deionized water, stir evenly to obtain a cerium solution; weigh 0.54 g of ferric chloride hexahydrate (2 mmol), 25 mg of sodium sulfate (0.176 mmol), and 78 mg of sodium dihydrogen phosphate (0.65 mmol) and dissolve them in 80 ml of water to obtain an iron solution.
[0027] The iron solution was slowly added drop by drop into the cerium solution under stirring, and stirred vigorously at 60°C for 30 min; under stirring, 0.01 mol / L NaOH solution was added to adjust the pH to 10, and stirred at 60°C for 0.5 hour; after stirring, the mixed solution was transferred to a hydrothermal synthesis reactor lined with polytetrafluoroethylene, and the hydrothermal synthesis reactor was sealed and placed in an oven for hydrothermal treatment at a temperature of 180°C for 16 hours; after cooling, the liquid precipitate was centrifuged, washed with deionized water and anhydrous ethanol, and dried at 80°C overnight; after drying, it was placed in a tubular furnace, and a mixture of hydrogen and argon with a volume ratio of 1:3 was introduced, and the temperature was raised to 500°C at a heating rate of 2°C / min, and then calcined at a constant temperature for 4 hours. After calcination, it was ground into powder and recorded as catalyst A. The SEM characterization results of the catalyst are shown as follows Figure 1 As shown, the TEM results are Figure 2 As shown, it can be seen that the catalyst presents an obvious spherical structure. The N2 adsorption isotherm of the catalyst at -196 °C and the corresponding pore size distribution are shown in Figure 3 As shown, it can be seen that the N2 adsorption isotherms all show hysteresis loops when the partial pressure (P / P0) is greater than 0.4, indicating the presence of mesopores in these samples, which is also confirmed by the pore size distribution, which helps to improve the reaction efficiency and adsorption capacity.
[0028] Example 2
[0029] The preparation of the catalyst was repeated in Example 1, except that the amount of ferric chloride hexahydrate was changed to 1.08 g, and was recorded as Catalyst B.
[0030] Example 3
[0031] The preparation of the catalyst was repeated in Example 1, except that the amount of ferric chloride hexahydrate was changed to 0.27 g, and was recorded as Catalyst C.
[0032] Example 4
[0033] The preparation of the catalyst was repeated in Example 1, except that 25 mg of sodium sulfate and 78 mg of sodium dihydrogen phosphate were replaced with 50 mg of sodium sulfate and 156 mg of sodium dihydrogen phosphate, which was recorded as catalyst D.
[0034] Example 5
[0035] The preparation of the catalyst was repeated in Example 1, except that 25 mg of sodium sulfate and 78 mg of sodium dihydrogen phosphate were replaced with 13 mg of sodium sulfate and 39 mg of sodium dihydrogen phosphate, which was recorded as Catalyst E.
[0036] Example 6
[0037] The preparation of the catalyst was repeated in Example 1, the only difference from Example 1 being that “no sodium salt was used”, and was recorded as Catalyst F.
[0038] Example 7
[0039] The preparation of the catalyst was repeated in Example 1, except that 25 mg of sodium sulfate and 78 mg of sodium dihydrogen phosphate were replaced with 121 mg of sodium bicarbonate, and the catalyst was recorded as Catalyst G.
[0040] Example 8
[0041] The preparation of the catalyst was repeated in Example 1, the only difference from Example 1 being that the temperature of the hydrothermal treatment was changed to 160° C., and was recorded as Catalyst H.
[0042] Example 9
[0043] The preparation of the catalyst was repeated as in Example 1, the only difference from Example 1 being that the temperature of the hydrothermal treatment was changed to 200 degrees Celsius, and was recorded as Catalyst I.
[0044] Example 10
[0045] The preparation of the catalyst was repeated in Example 1, except that the calcination atmosphere was changed to air, and the catalyst was recorded as Catalyst J.
[0046] Embodiment 11
[0047] The preparation of the catalyst was repeated as in Example 1, except that the constant temperature calcination temperature was changed to 300 degrees Celsius, and was recorded as catalyst K.
[0048] Example 12
[0049] The preparation of the catalyst was repeated as in Example 1, except that the constant temperature calcination temperature was changed to 400 degrees Celsius, and was recorded as catalyst L.
[0050] Example 13
[0051] The preparation of the catalyst was repeated in Example 1, the only difference from Example 1 being that the constant temperature calcination temperature was changed to 600 degrees Celsius, and was recorded as catalyst M.
[0052] Embodiment 14
[0053] The preparation of the catalyst was repeated in Example 1, except that the heating rate during calcination was changed to 1° C. / min, and was recorded as Catalyst N.
[0054] Embodiment 15
[0055] The preparation of the catalyst was repeated in Example 1, except that the heating rate during calcination was changed to 5° C. / min, and was recorded as Catalyst O.
[0056] 0.1 g of the catalyst of Examples 1-15 was respectively placed in a 50 ml stainless steel autoclave reactor, 10 ml of deuterated methanol was added, carbon dioxide was introduced to make the reactor pressure 3.5 MPa, the reaction temperature was 140° C., the stirring rate was 500 r / min, and the reaction time was 6 hours. After the reaction was completed, the liquid phase product was collected and analyzed by gas chromatograph (GC). The analysis results are shown in Table 1.
[0057] Table 1 Performance of the catalysts prepared in Examples 1-15
[0058]
[0059]
[0060] It can be seen from Table 1 that the catalyst of the present invention has good selectivity, especially Example 1, the yield is relatively high, and the selectivity reaches 99.99%.
[0061] The yield in Table 1 is the activity evaluation index of the catalyst, which is calculated based on the number of millimoles of DMC obtained per gram of catalyst, in units of mmol / g, and the calculation formula is as follows:
[0062]
[0063] Where: m DMC Indicates the mass of DMC in the product, in g, M DMC Indicates the molar mass of DMC in g / mol, m cat It represents the mass of the catalyst in g.
[0064] From the comparison of the catalytic results of the catalysts of Example 6 and Example 1 in Table 1, it can be seen that the incorporation of sodium salt during the preparation of the catalyst is beneficial to improving its catalytic activity. The reason may be that the incorporation of Na salt causes the reactant particles formed by etching to form more defects, thereby increasing the active sites of the catalyst.
[0065] Comparison of the catalytic results of the catalysts in Example 10 and Example 1 shows that the calcination atmosphere during catalyst preparation has a great influence on the catalytic activity. The catalyst prepared by calcination in a hydrogen-argon atmosphere has a catalytic effect that is approximately doubled relative to the catalyst calcined in air. In the catalyst prepared by calcination in a hydrogen-argon atmosphere of the present invention, hydrogen has a reducing effect and argon mainly has a protective gas effect. The reduction with hydrogen may change the interaction between the carrier and the metal component, as well as the electronic structure, thereby affecting the catalytic effect.
[0066] Cyclic stability test example
[0067] 0.1 g of the catalyst of Example 1 was placed in a stainless steel autoclave reactor containing 100 ml of solvent, 10 ml of deuterated methanol was added, carbon dioxide was introduced to make the reactor pressure 3.5 MPa, the reaction temperature was 140° C., the stirring rate was 500 r / min, and the reaction time was 6 hours. After each reaction, the solid-liquid mixture in the autoclave was centrifuged and the catalyst was washed and then used again. The catalyst was tested for cyclic stability, and the collected liquid products were analyzed by gas chromatograph (GC). The analysis results are shown in Table 2.
[0068] Table 2 Cyclic stability test results of catalysts
[0069] Cycle times Yield (mmol / g) Deuterated dimethyl carbonate selectivity (%) 1 16.31 99.99 2 16.22 99.98 3 15.99 99.99 4 15.89 99.99 5 16.17 99.99
[0070] It can be seen from Table 2 that after 5 cycles of testing, the catalytic activity of the catalyst hardly decreased during the cyclic use, the yield of deuterated dimethyl carbonate hardly changed much, and the selectivity was still maintained above 99%, showing good cyclic stability, providing reliability for long-term industrial applications, and having considerable advantages and potential application value.
[0071] The above description is only part of the embodiments of the present invention and is not intended to limit the present invention. All equivalent changes and modifications made according to the content of the present invention are within the protection scope of the present invention.
Claims
1. A method for preparing a catalyst for catalyzing deuterated methanol to directly synthesize deuterated dimethyl carbonate, characterized in that The steps include: 1) Preparation of cerium solution: dissolving cerium salt in deionized water to obtain cerium solution; 2) Preparation of iron solution: dissolve the iron salt in deionized water, then add sodium salt to the solution for post-treatment, stir well and evenly to obtain an iron solution; 3) slowly adding the iron solution of step 2) dropwise into the cerium solution of step 1) under stirring, and continuing stirring; 4) Add alkali to the mixed solution stirred evenly in step 3) to adjust the pH to > 10, and heat and stir; 5) After stirring, the mixed solution is transferred to a hydrothermal synthesis reactor with a polytetrafluoroethylene liner, and the hydrothermal synthesis reactor is sealed and transferred to an oven for hydrothermal treatment; 6) After the hydrothermal treatment, the solution is cooled to room temperature, centrifuged, washed, dried, calcined in a mixture of hydrogen and argon, and finally ground to obtain the target catalyst.
2. The method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate as claimed in claim 1, characterized in that The cerium salt in step 1) is one or more of cerium chloride, cerium nitrate, cerium sulfate, and ammonium cerium nitrate, preferably cerium nitrate.
3. The method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate as claimed in claim 1, characterized in that The iron salt in step 2) is one or more of ferric chloride, ferric nitrate, and ferric sulfate, preferably ferric chloride; The molar ratio of the iron salt to the cerium salt is 1:5-20, preferably 1:8-10.
4. The method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate as claimed in claim 1, characterized in that The sodium salt in step 2) is one or more of sodium chloride, sodium dihydrogen phosphate, sodium sulfate, sodium formate, and sodium tungstate, preferably a mixture of sodium dihydrogen phosphate and sodium sulfate, and the molar ratio of sodium dihydrogen phosphate to sodium sulfate is 2-5:1, preferably 3.5-4:1; The molar ratio of the sodium salt to the cerium salt is 1:10-50, preferably 1:20-24.
5. The method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate as claimed in claim 1, characterized in that In step 4), the heating temperature is 50-80°C, preferably 60°C, and the heating time is 20-40 minutes.
6. The method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate as claimed in claim 1, characterized in that In step 5), the temperature of the hydrothermal treatment is 160-200° C., preferably 180-185° C., and the time of the hydrothermal treatment is 12-20 hours, preferably 16-18 hours.
7. The method for preparing a catalyst for catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate as claimed in claim 1, characterized in that In step 6), the volume flow ratio of hydrogen to argon is 1:2-4, preferably 1:3, and the calcination procedure is: after uniformly heating from room temperature to a constant temperature calcination temperature, the constant temperature is maintained for a period of time, the heating rate is 1-5°C / min, preferably 2°C / min, the constant temperature calcination temperature is 400-600°C, preferably 500°C, and the constant temperature calcination time is 3-6h.
8. A catalyst prepared by the method as described in any one of claims 1 to 7.
9. Use of the catalyst as claimed in claim 8 in the reaction of catalyzing the direct esterification of deuterated methanol and carbon dioxide to synthesize deuterated dimethyl carbonate, characterized in that The reaction raw materials include deuterated methanol and carbon dioxide gas. Specifically, a catalyst is placed in a stainless steel autoclave reactor, deuterated methanol is added, and carbon dioxide is introduced for stirring reaction to convert the deuterated methanol into deuterated dimethyl carbonate.
10. The use according to claim 9, characterized in that The reaction temperature is 130-150°C, the carbon dioxide pressure is 3.0-5.0MPa, the stirring rate is 300-600r / min, and the reaction time is 4-8h.