阅读说明：本技术 一种苯酚和碳酸二甲酯制备苯甲醚的催化剂 (Catalyst for preparing anisole from phenol and dimethyl carbonate ) 是由 张海永 张璐 王永刚 许德平 于 2020-12-24 设计创作，主要内容包括：本发明提供一种苯酚和碳酸二甲酯制备苯甲醚的催化剂,其利用IIA族碱土金属盐和硝酸铝经氢氧化钠和碳酸钠共沉淀生成水滑石,焙烧后再以氟硅酸盐和/或氟铝酸盐对其进行插层改性获得。(The invention provides a catalyst for preparing anisole from phenol and dimethyl carbonate, which is prepared by coprecipitating alkaline earth metal salt of IIA family and aluminum nitrate with sodium hydroxide and sodium carbonate to generate hydrotalcite, roasting, and then carrying out intercalation modification on the hydrotalcite with fluosilicate and/or fluoroaluminate.)

1. A catalyst for synthesizing anisole from phenol and dimethyl carbonate is characterized in that group IIA alkaline earth metal salt and aluminum nitrate are subjected to coprecipitation by sodium hydroxide and sodium carbonate to generate hydrotalcite, and after roasting, the hydrotalcite is subjected to intercalation modification by fluosilicate and/or fluoroaluminate to obtain the catalyst.

2. The catalyst of claim 1, wherein the alkaline earth metal salt is one or more of a nitrate, chloride, sulfate of magnesium, calcium.

3. The catalyst of claim 1, wherein the intercalation modifier is one or more of sodium fluorosilicate, ammonium fluorosilicate, sodium fluoroaluminate, ammonium fluoroaluminate.

4. The catalyst according to claim 1, wherein the concentration of the fluorosilicate or fluoroaluminate solution is 0.0025 to 0.1mol/L, preferably 0.005 to 0.025 mol/L.

5. The catalyst according to claim 1, wherein the temperature for modifying the hydrotalcite-like compound by the fluosilicate or fluoroaluminate solution is between room temperature and 180 ℃, preferably between 30 and 120 ℃.

6. A preparation method of a catalyst for synthesizing anisole from phenol and dimethyl carbonate is characterized in that group IIA alkaline earth metal salt and aluminum nitrate are subjected to coprecipitation by sodium hydroxide and sodium carbonate to generate hydrotalcite, and after roasting, the hydrotalcite is subjected to intercalation modification by fluosilicate and/or fluoroaluminate to obtain the catalyst.

7. The method of claim 6, wherein the alkaline earth metal salt is one or more of a nitrate, chloride, sulfate salt of magnesium, calcium.

8. The method of claim 6, wherein the intercalation modifier is one or more of sodium fluorosilicate, ammonium fluorosilicate, sodium fluoroaluminate, ammonium fluoroaluminate.

9. A process according to claim 6 wherein the concentration of fluorosilicate or fluoroaluminate solution is from 0.0025 to 0.1mol/L, preferably from 0.005 to 0.025 mol/L.

10. The process according to claim 6, wherein the temperature for modifying the hydrotalcite-like compound with the fluorosilicate or fluoroaluminate solution is from room temperature to 180 ℃, preferably from 30 to 120 ℃.

Technical Field

The invention relates to a catalyst for preparing anisole from phenol and dimethyl carbonate, belonging to the field of chemistry.

Background

Anisole is an important organic chemical raw material, and has important application in the aspects of dyes, medicines, spices, resins, synthetic fibers and the like.

At present, anisole is produced by mainly using phenol and dimethyl sulfate as raw materials in the industry, dimethyl sulfate is a hypertoxic substance, a large amount of high-toxicity waste water and solid waste are generated, the environmental pollution is serious, and part of manufacturers are forced to limit production and stop production, so that the healthy development of downstream related industries is seriously influenced. Dimethyl carbonate is a novel green chemical raw material with low pollution and environmental friendliness, is used as a methylation reagent to react with phenol to synthesize anisole, is harmless to the environment, is non-toxic and pollution-free, and is widely concerned.

CN201911167801.6 discloses a catalyst for preparing anisole, which is prepared by mixing alkali metal or alkaline earth metal chloride salt and assistant metal chloride salt by dry mixing method, and is used for synthesizing anisole from phenol and dimethyl carbonate, such as CaCl2-AlCl3 or CaCl2-ZnCl2 mixture, etc., with good effect.

CN201911141907.9 discloses a method for synthesizing anisole by catalyzing Na-sodium hydroxide/gamma-Al 2O3, which takes solid super alkali Na-sodium hydroxide/gamma-Al 2O3 as a catalyst to catalyze phenol and dimethyl carbonate to react under the protection of nitrogen at 180-200 ℃ to synthesize anisole. CN201911141104.3 discloses that a graphene oxide supported sodium hydroxide-Al 2O3 catalyst is used for anisole synthesis, and the conversion rate is 97.13% and the selectivity is 92.36% after 6 hours of liquid phase reaction at 220 ℃. CN201911141883.7 discloses a KF/Mg2+ Fe3+ -LDHs catalyst and application thereof in catalytic synthesis of anisole, wherein carriers Mg2+ Fe3+ -LDHs are prepared by a urea method and a structure recovery method, and then the KF/Mg2+ Fe3+ -LDHs catalyst is prepared by an immersion method with absolute ethyl alcohol as a dispersing agent. Dimethyl carbonate and phenol are added into a hydrothermal reaction kettle according to the mol ratio of 2:1, a KF/Mg2+ Fe3+ -LDHs catalyst with the total mass of 3% is added, the reaction is carried out for 4 hours under the protection of nitrogen, the conversion rate can reach 97.94% at 200 ℃, and the selectivity is 95.32%.

CN200710062332.2 discloses a method for liquid-phase synthesis of anisole by catalyzing a mixed oxide Fy/M2+ 1-x (M3+) xOx-y/2 modified by fluorine, wherein M2+ is a divalent metal cation, M3+ is a trivalent metal cation, x is 0.2-0.45, and y is 0.05-0.2. The divalent metal salt and the trivalent metal salt generate precipitates under the action of hydroxide and fluoride, the catalyst is generated after roasting under the action of nitrogen, the phenol conversion rate is 93.67 percent and the anisole selectivity is 94.36 percent after the reaction is carried out for 16 hours at 220 ℃.

The above patents are almost all liquid phase reactions under low temperature conditions, or batch reactions in a reaction vessel under high pressure conditions. According to the characteristics of the reaction, the low temperature is favorable for the selectivity of anisole, but limits the conversion rate and the production and processing capacity of raw materials from the aspect of mechanics. The gas phase reaction at high temperature can improve the productivity of the reaction. CN200310123602.8 discloses a method for synthesizing p-methyl anisole by gas phase catalysis, wherein the catalyst is active carbon or X-type molecular sieve, but the effect of the catalyst is better after the catalyst is treated by fluoride or hydroxide of alkali metal.

Disclosure of Invention

The invention discloses a catalyst for preparing anisole from phenol and dimethyl carbonate, which is characterized in that group IIA alkaline earth metal salt and aluminum nitrate are subjected to coprecipitation by sodium hydroxide and sodium carbonate to generate hydrotalcite, and after roasting, the hydrotalcite is subjected to intercalation modification by fluosilicate and/or fluoroaluminate to obtain the catalyst.

According to a preferred embodiment, wherein the alkaline earth metal salt is one or more of a nitrate, chloride, sulphate of magnesium, calcium;

according to a preferred embodiment, wherein the intercalation modifier is one or more of sodium fluorosilicate, ammonium fluorosilicate, sodium fluoroaluminate, ammonium fluoroaluminate;

according to a preferred embodiment, the concentration of the fluorosilicate or fluoroaluminate solution is 0.0025 to 0.1mol/L, preferably 0.005 to 0.025 mol/L.

According to a preferred embodiment, the temperature for modifying the hydrotalcite-like compound with the fluorosilicate or fluoroaluminate solution is between room temperature and 180 ℃, preferably between 30 and 120 ℃.

The invention also discloses a preparation method of the catalyst for synthesizing anisole from phenol and dimethyl carbonate, which is characterized in that group IIA alkaline earth metal salt and aluminum nitrate are subjected to coprecipitation by sodium hydroxide and sodium carbonate to generate hydrotalcite, and after roasting, the hydrotalcite is subjected to intercalation modification by fluosilicate and/or fluoroaluminate to obtain the catalyst.

According to a preferred embodiment, wherein the alkaline earth metal salt is one or more of a nitrate, chloride, sulphate of magnesium, calcium;

according to a preferred embodiment, wherein the intercalation modifier is one or more of sodium fluorosilicate, ammonium fluorosilicate, sodium fluoroaluminate, ammonium fluoroaluminate;

according to a preferred embodiment, the concentration of the fluorosilicate or fluoroaluminate solution is 0.0025 to 0.1mol/L, preferably 0.005 to 0.025 mol/L.

According to a preferred embodiment, the temperature for modifying the hydrotalcite-like compound with the fluorosilicate or fluoroaluminate solution is between room temperature and 180 ℃, preferably between 30 and 120 ℃.

The technology prepares a novel hydrotalcite catalyst with better performance: the method is characterized in that a hydrotalcite-type layered composite oxide has the characteristic of memory effect, double salts such as ammonium fluoroaluminate or ammonium fluosilicate are used for carrying out structure reconstruction on MgAl and CaAl hydrotalcite, the double-salt anions are used for propping open layered plates of the hydrotalcite, ammonia escapes in a gaseous state after roasting, fluoroaluminate radicals are left between the layered plates to form pillared hydrotalcite, the spacing between the layered plates is enlarged, the diffusion rate of reactants is improved, and the acidity and alkalinity of a catalyst is adjusted. The acid-base amphoteric pillared hydrotalcite obtained by the method can effectively improve the effect of the catalyst. The production process has no equipment corrosion, is an environment-friendly catalyst and production process, and has good industrial application prospect.

Drawings

FIG. 1 is an SEM image of a sample obtained in example 1, and the surface of the sample is a silk-screen fibrous porous structure.

FIG. 2 acid base TPD of the catalyst obtained in example 2.

Detailed Description

The terms used in the present invention have the ordinary meaning in the art and are common words in the art. The substances and reactions involved in the present invention are those which are commonly known in the art or which are commercially available, unless otherwise specified.

According to the law of conservation of mass, after methyl in DMC exchanges with H in phenolic hydroxyl, DMC generates CO2 and water molecules, alkali nitrate, alkali chloride, fluorine salt and the like are all water-soluble substances, and alkali nitrate is very stable and generates soluble nitrite after high-temperature roasting, so that loss, inactivation and the like of active components in a system generated by water are difficult to avoid.

According to the reaction mechanism, the reaction requires an acid-base bifunctional catalyst. The literature reports that the MgAl hydrotalcite modified by ammonium fluoride is used for synthesizing anisole by a liquid phase method. Because the requirement of the reaction on shape-selective catalysis is not high under a proper acid-base ratio, the technology discloses a novel hydrotalcite catalyst with better performance on the basis that: the MgAl hydrotalcite is structurally reconstructed by ammonium fluoroaluminate, so that layered plates of the hydrotalcite are propped open by fluoroaluminate anions, ammonia escapes in a gaseous state after roasting, fluoroaluminate radicals are remained between the layered plates to form pillared hydrotalcite, the spacing between the layered plates is enlarged, the diffusion rate of reactants is improved, and the acidity and alkalinity of the catalyst is modulated. The acid-base amphoteric pillared hydrotalcite obtained by the method can effectively improve the effect of the catalyst.

The present inventors have made intensive studies and completed the present invention. The method comprises the following steps:

a. precipitating Mg salt or a mixture of Ca salt and Al salt with an alkali solution of carbonate and hydroxide to prepare layered composite metal hydroxide, and roasting to obtain hydrotalcite-like layered composite metal oxide.

b. The composite metal oxide is ion exchanged or structurally reconstructed in water solution of fluoroaluminate or fluorosilicate in beaker or hydrothermal condition, and fluoroaluminate or fluorosilicate ion is inserted between layers.

c. And roasting the modified hydrotalcite type composite metal oxide to obtain the catalyst.

Example 1

In beaker A, 100ml of solution A was prepared from 0.12mol of magnesium nitrate hexahydrate and 0.03mol of aluminum nitrate nonahydrate with deionized water, 100ml of solution B was prepared from 0.255mol of sodium hydroxide and 0.0648mol of anhydrous sodium carbonate with deionized water, and 100ml of deionized water was added in beaker C. After dissolution with stirring, solution a and solution B were pumped into beaker C at a rate using a peristaltic pump. After the completion of the reaction, the solution in the beaker C was stirred at room temperature for 10 hours while maintaining the pH at 9-11. And after stirring, filtering the slurry in the beaker C, and washing the slurry to be neutral by using deionized ions. And drying the obtained precipitate in an oven at 110 ℃ for 12h to obtain the product, namely the hydrotalcite-like material, which is recorded as Mg4 Al-LDH. And reserving for subsequent tests.

And (3) putting the Mg4Al-LDH into a muffle furnace for roasting, heating at the rate of 3 ℃/min, heating to 450 ℃ from room temperature, and roasting for 5 h. And after the calcination is finished, naturally cooling to room temperature, and recording as Mg4 Al-LDO.

0.1g of Mg4Al-LDO was taken to carry out gas phase alkylation of phenol with dimethyl carbonate. The molar ratio of phenol to dimethyl carbonate is 1:3, the feeding amount is 0.2ml/h, the reaction temperature is 350 ℃, the reaction time is 2.5h, nitrogen is used as a carrier gas, and the nitrogen flow is 10 ml/min. The product was absorbed in isopropanol at 0 ℃ and analyzed by gas chromatography to give 98.87% conversion and 82.93% selectivity. The SEM image of the resulting product is shown in FIG. 1.

Example 2

50ml of 0.1mol/L ammonium fluoroaluminate solution was added to 1g of Mg4 Al-LDH. Stirring was carried out at room temperature for 6 h. And after stirring, carrying out suction filtration, washing, drying and roasting to obtain a product, namely Mg4Al-LDO-0.1 FAl. A0.1 g sample was taken for gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 99.22% and a selectivity of 69.98%. The resulting catalyst has an acid base TPD shown in FIG. 2, and has a weak base content of 0.21mmol/g, a strong base content of 0.408mmol/g, a weak acid content of 0.084mmol/g, and a strong acid content of 0.305 mmol/g.

Example 3

And adding 1g of Mg4Al-LDH into 50ml of 0.025mol/L ammonium fluoroaluminate solution, stirring at room temperature for 6 hours, then carrying out suction filtration, washing, drying and roasting to obtain a product, namely Mg4Al-LDO-0.025 FAl. A sample of 0.1g was taken for the gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 99.04% and a selectivity of 83.4%.

Example 4

And adding 50ml of 0.01mol/L ammonium fluoroaluminate solution into 1g of Mg4Al-LDH, stirring at room temperature for 6 hours, then carrying out suction filtration, washing, drying and roasting to obtain a product, namely Mg4Al-LDO-0.01 FAl. A0.1 g sample was taken for the gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 98.63% and a selectivity of 93.78%.

Example 5

And adding 50ml of 0.005mol/L ammonium fluoroaluminate solution into 1g of Mg4Al-LDH, stirring at room temperature for 6 hours, then carrying out suction filtration, washing, drying and roasting to obtain a product, namely Mg4Al-LDO-0.005 FAl. A0.1 g sample was taken for the gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 98.49% and a selectivity of 90.13%.

Example 6

And adding 50ml of 0.0025mol/L ammonium fluoroaluminate solution into 1g of Mg4Al-LDH, stirring at room temperature for 6 hours, then carrying out suction filtration, washing, drying and roasting to obtain a product, namely Mg4Al-LDO-0.0025 FAl. A0.1 g sample was taken for gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 99.55% and a selectivity of 89.71%.

Example 7

Taking 1g of Mg4Al-LDH, adding 50ml of 0.01mol/L ammonium fluoroaluminate solution, carrying out hydrothermal treatment for 6h at 100 ℃, then carrying out suction filtration, washing, drying and roasting, and marking as Mg4Al-LDO-0.01 FAl-100. A0.1 g sample was taken for the gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 98.34% and a selectivity of 94.40%.

Example 8

Taking 1g Mg4Al-LDH, adding 50ml of 0.01mol/L ammonium fluoroaluminate solution, carrying out hydrothermal treatment for 6h at 180 ℃, then carrying out suction filtration, washing, drying and roasting, and marking as Mg4Al-LDO-0.01 FAl-180. A0.1 g sample was taken for gas phase alkylation of phenol with dimethyl carbonate under the same reaction conditions as in example 1, and the product was analyzed by gas chromatography to give a conversion of 98.77% and a selectivity of 85.31%.

The specific examples given in this detailed description of the invention are intended to be illustrative of the invention and are not intended to be limiting.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.