阅读说明：本技术 一种藜芦醚的制备方法 (Preparation method of veratrole ) 是由 王锐 范立耸 李俊平 于 2020-12-11 设计创作，主要内容包括：本发明公开了一种制备藜芦醚的方法,采用一种双层床催化剂,即SAPO分子筛与石墨烯负载镧-铈-硼按照一定的装填比例、顺序组装成混装催化剂。该催化剂能够高效地催化邻苯二酚与甲醇的反应,显著提高了该工艺中的藜芦醚选择性和收率,且具有较好的稳定性。(The invention discloses a method for preparing veratrole, which adopts a double-bed catalyst, namely a mixed catalyst which is formed by sequentially assembling SAPO molecular sieves and graphene loaded lanthanum-cerium-boron according to a certain filling proportion. The catalyst can efficiently catalyze the reaction of catechol and methanol, remarkably improves the selectivity and yield of veratrole in the process, and has good stability.)

1. A preparation method of veratrole is characterized in that catechol and methanol are used as raw materials, and the veratrole is prepared by etherification under the common catalysis of a metal catalyst and a molecular sieve catalyst;

the metal catalyst comprises active metal and a carrier, wherein the active metal comprises lanthanum, cerium and boron, and the carrier is graphene.

2. The method for preparing veratrole according to claim 1, wherein the loading amount of lanthanum element in the metal catalyst is 0.1-15 wt%, preferably 5-12 wt% of the carrier, and the molar ratio of lanthanum, cerium and boron is 1: 0.1-0.5: 0.1-0.5, preferably 1:0.2-0.3: 0.2-0.3.

3. The method for preparing veratrole according to claim 1, wherein the catalyst is prepared by grinding graphite oxide into powder, ultrasonically dispersing in deionized water for 1-3h, adding lanthanum salt, cerium salt and boron salt, adjusting pH to 5-6.5, stirring uniformly, adding sodium borohydride, reacting at room temperature for 6-12h, washing, drying and roasting;

preferably, after the reaction is finished, the catalyst is washed by ethanol water solution, dried at the temperature of 110-130 ℃ for 8-12h and then roasted at the temperature of 300-400 ℃ for 4-8h in nitrogen atmosphere.

4. The method for preparing veratrole according to claim 1, wherein the lanthanum salt is added in an amount of 0.1-15 wt%, preferably 5-12 wt% of the graphite oxide, the molar ratio of lanthanum, cerium and boron in the lanthanum salt, cerium salt and boron salt is 1: 0.1-0.5: 0.1-0.5, preferably 1:0.2-0.3: 0.2-0.3;

preferably, the lanthanum salt is selected from one or more of lanthanum phosphate, lanthanum nitrate, lanthanum acetate, lanthanum sulfate and lanthanum chloride, the cerium salt is selected from one or more of cerium phosphate, cerium nitrate, cerium acetate, cerium sulfate and cerium chloride, and the boron salt is selected from one or more of boron phosphate and boron trichloride.

5. The method for preparing veratrole according to claim 1, wherein the ratio of the molecular sieve catalyst to the metal catalyst to the mass is 1:0.8-1:2, preferably 1:0.9-1: 1.1;

preferably, the molecular sieve is a SAPO molecular sieve selected from one or more of SAPO5, SAPO11, SAPO17, SAPO18, SAPO34, SAPO35 and SAPO 44; preferably SAPO-34;

preferably, the molecular sieve is subjected to pretreatment by roasting at 850-900 ℃ in an air atmosphere for 10-12 h.

6. The method of claim 1, wherein said veratrole is selected from the group consisting of veratrole,

when the veratrole is prepared, a phosphorus-containing auxiliary agent is also added into the raw material liquid, wherein the addition amount of the phosphorus-containing auxiliary agent is 0.45-0.65 wt% of the total mass of catechol and methanol, and preferably 0.50-0.60 wt%;

preferably, the phosphorus-containing additive is: one or more of phosphoric acid, methyl phosphate, dimethyl phosphate, trimethyl phosphate, diethyl phosphate, triethyl phosphate, pyrophosphoric acid, metaphosphoric acid and polyphosphoric acid, and phosphoric acid and trimethyl phosphate are preferred.

7. The method for preparing veratrole according to claim 1, wherein the molar ratio of catechol to methanol is 1:3 to 1:10, preferably 1:5 to 1: 6.

8. the method for preparing veratrole according to claim 1, wherein the reaction temperature is 250 to 290 ℃, the pressure is normal pressure, and the mass space velocity of catechol relative to the total mass of the two catalysts is 0.1 to 0.3h^-1。

The technical field is as follows:

the invention relates to the field of fine chemical engineering, and particularly relates to a preparation method of veratrole.

Background art:

veratrole, also known as o-dimethyl ether, is an important fine chemical raw material, can be used as an important intermediate in medicine, pesticide and chemical synthesis, and is an important raw material for synthesizing essence and perfume and a raw material for synthesizing medicine. At present, the preparation of veratrole mainly has three process routes, and all uses pyrocatechol as a raw material. Among them, the first method utilizes catechol and dimethyl sulfate for methylation, which is also the most commonly used method in industry. But because dimethyl sulfate belongs to highly toxic chemicals, great harm is caused to human bodies and the environment by carelessness in the using process. The second method is to react catechol with sodium hydroxide to produce sodium salt, which is then reacted with chloromethane under certain pressure to obtain product, but the product has strict requirement on reaction condition, low yield and difficult separation. The third process adopts a catechol-methanol system, and the required raw materials have low toxicity and corrosivity and are cheap and easy to obtain. Compared with the former two processes, the process has the advantages of low toxicity and corrosivity of raw materials, low price, easy obtainment and higher economy, is an environment-friendly process, and is imperative for further development.

At present, the research of catechol-methanol system mainly focuses on catalyst optimization to improve the guaiacol selectivity, and the research on improving the veratrole selectivity is less. In the article "preparation and characterization of AlPxO catalyst and its catalytic performance in O-monoetherification reaction of catechol", bang prepared AlPxO (x ═ 0,0.33,0.5,1.0,1.5,2.0) catalyst by precipitation method, at 280 ℃, catechol conversion rate was 18.9 to 97.6%, guaiacol selectivity was 15.0 to 94.6%, veratrole selectivity was 0 to 4.8%, and maximum veratrole yield was 3.4%. In the US patent 005786520A, LaPO4/CsPO4/SmPO4 catalyst is adopted, under the condition of 270-360 ℃, the conversion rate of catechol is 14.1-97.5%, the selectivity of guaiacol is 64.5-100%, the selectivity of veratrole is 4.2-28.5%, and the highest yield of veratrole is 26.8%. In Journal of Molecular Catalysis A, Chemical 372(2013) 79-83, Ali Abedi Jafari adopts titanium modified lanthanide catalyst, changes the catalytic activity by adjusting the relative proportion of lanthanum and titanium, and under the condition of 255-300 ℃, the conversion rate of catechol is 67.1-84.3%, the selectivity of guaiacol is 63.6-90.9%, the selectivity of veratrole is 6.5-23.6%, and the highest yield of veratrole is 21.6%. In the above studies, the product is mainly guaiacol, veratrole selectivity is very low (< 28.5%), and the yield is only 26.8% at most. Therefore, how to develop a preparation method of veratrole to improve the selectivity and yield of veratrole in a catechol-methanol system is a main research direction at present.

The invention content is as follows:

the invention aims to provide a preparation method of veratrole, which comprises a high-efficiency catalyst used in a catechol-methanol system, namely an SAPO molecular sieve and a graphene loaded lanthanum-cerium-boron double-bed catalyst, and improves the selectivity and the yield of the veratrole.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for preparing veratrole comprises the steps of adopting catechol and methanol as raw materials, and carrying out etherification under the catalysis of a metal catalyst and a molecular sieve catalyst to obtain the veratrole.

The metal catalyst comprises active metal and a carrier, wherein the active metal comprises lanthanum, cerium and boron, and the carrier is graphene.

In the invention, the loading amount of lanthanum element in the metal catalyst is 0.1-15 wt%, preferably 5-12 wt% of the carrier, and the molar ratio of lanthanum, cerium and boron is 1: 0.1-0.5: 0.1-0.5, preferably 1:0.2-0.3: 0.2-0.3.

The invention also provides a preparation method of the catalyst, which comprises the steps of grinding graphite oxide into powder, ultrasonically dispersing the powder in deionized water for 1-3h, then adding lanthanum salt, cerium salt and boron salt, adjusting the pH value to 5-6.5, uniformly stirring, adding sodium borohydride, reacting at normal temperature for 6-12h, washing, drying and roasting.

Preferably, after the reaction is finished, the catalyst is washed by ethanol water solution, dried at the temperature of 110-130 ℃ for 8-12h and then roasted at the temperature of 300-400 ℃ for 4-8h in nitrogen atmosphere.

Preferably, the mass of the lanthanum element contained in the added lanthanum salt is 0.1-15 wt% of the mass of the graphite oxide, preferably 5-12%, and the molar ratio of the lanthanum element, the cerium element and the boron element in the lanthanum salt, the cerium salt and the boron salt is 1: 0.1-0.5: 0.1-0.5, preferably 1:0.2-0.3: 0.2-0.3.

Preferably, the lanthanum salt is selected from one or more of lanthanum phosphate, lanthanum nitrate, lanthanum acetate, lanthanum sulfate and lanthanum chloride, the cerium salt is selected from one or more of cerium phosphate, cerium nitrate, cerium acetate, cerium sulfate and cerium chloride, and the boron salt is selected from one or more of boron phosphate and boron trichloride;

preferably, the adding amount of the sodium borohydride is based on the reduction of all carbon-oxygen structures in the graphite oxide; the reduced graphite oxide forms a graphene structure.

The mass ratio of the molecular sieve catalyst to the metal catalyst is 1:0.8-1:2, preferably 1:0.9-1: 1.1;

the molecular sieve is preferably a SAPO molecular sieve selected from one or more of SAPO5, SAPO11, SAPO17, SAPO18, SAPO34, SAPO35, and SAPO 44; SAPO-34 is preferred.

Preferably, the molecular sieve is subjected to pretreatment by roasting at 850-900 ℃ in air for 10-12 h;

in some embodiments of the present invention, the activated SAPO molecular sieve and the metal catalyst are assembled into a dual-bed catalyst according to a certain loading ratio and sequence, and the dual-bed catalyst is loaded in the fixed bed reactor, wherein the loading sequence of the molecular sieve and the metal catalyst can be, but is not limited to, the molecular sieve is loaded in an upper bed layer, the metal catalyst is loaded in a lower bed layer, or the metal catalyst is loaded in an upper bed layer, and the molecular sieve is loaded in a lower bed layer;

in the invention, a phosphorus-containing auxiliary agent is also added into the raw material liquid during the preparation of veratrole, wherein the addition amount of the phosphorus-containing auxiliary agent is 0.45-0.65 wt% of the total mass of catechol and methanol, and preferably 0.50-0.60 wt%. The phosphorus-containing additive comprises: one or more of phosphoric acid, methyl phosphate, dimethyl phosphate, trimethyl phosphate, diethyl phosphate, triethyl phosphate, pyrophosphoric acid, metaphosphoric acid and polyphosphoric acid, and phosphoric acid and trimethyl phosphate are preferred.

In the invention, reaction raw materials are mixed solution of catechol, methanol and phosphorus-containing auxiliary agent, and the mixed raw materials are subjected to double-bed catalyst to obtain veratrole reaction solution;

in the invention, the molar ratio of catechol to methanol is 1: 3-1: 10, preferably 1: 5-1: 6.

in the invention, the reaction temperature is 250-290 ℃, the pressure is normal pressure, and the mass space velocity of catechol relative to the total mass of the two catalysts is 0.1-0.3 h^-1。

In the invention, reaction raw materials are fed from the upper layer of the catalyst and discharged from the bottom.

After the reaction is finished, the reaction solution is separated and purified in a rectification mode to obtain veratrole.

The invention has the beneficial effects that:

in the double-bed catalyst provided by the invention, two catalytic components play a synergistic role. Wherein, the SAPO molecular sieve can play a role in activating catechol and methanol and improve the reaction activity. In the graphene-loaded lanthanum-cerium-boron metal catalyst, the large specific surface area of the graphene enables active components of lanthanum, cerium and boron to be highly dispersed on a carrier, and the metal utilization rate is high. Lanthanum and cerium elements can improve the acidity and alkalinity of the catalyst, and are beneficial to the O alkylation reaction; boron inhibits coke formation to improve catalyst stability and life. The SAPO molecular sieve and the graphene loaded lanthanum-cerium-boron can play a synergistic role, and compared with the traditional catalyst in a catechol-methanol system, the double-bed catalyst greatly improves the selectivity and the yield of veratrole.

The catalyst of the invention has high activity and stability and can stably run for a long time. Compared with the traditional catalyst in a catechol-methanol system, the double-bed catalyst can greatly improve the veratrole yield, the yield reaches 35.7 percent, and the veratrole selectivity is about 40 percent.

Description of the drawings:

FIG. 1: example 4 life test curve of catalyst.

The specific implementation mode is as follows:

for a better understanding of the present invention, the contents of the present invention are further illustrated below with reference to examples, which are provided to illustrate the basic principles, main features and advantages of the present invention, but the present invention is not limited by the following examples.

Example 1

The preparation and filling of the double-layer catalyst comprise the following three parts:

pretreatment of SAPO molecular sieve

The SAPO series molecular sieves used in the embodiment of the invention are all roasted for 12h at 900 ℃ in the air atmosphere for pretreatment;

secondly, preparing a graphene-loaded lanthanum-cerium-boron catalyst:

grinding 10g of graphite oxide into powder, performing ultrasonic dispersion in deionized water for 1 hour, and then adding a certain amount of lanthanum phosphate, cerium phosphate and boron phosphate, wherein the lanthanum element in the lanthanum phosphate accounts for 12% of the mass of the graphite oxide, and the molar ratio of the lanthanum element to the cerium element to the boron element is 1: 0.5: 0.5, dropwise adding a sodium hydroxide solution until the pH value is 6.5, stirring uniformly, adding 20g of sodium borohydride, reacting for 12h at normal temperature, washing with an ethanol water solution, performing suction filtration, drying the obtained sample at 110 ℃ for 10h, and roasting in a 400 ℃ muffle furnace for 4h to obtain the graphene-loaded lanthanum-cerium-boron catalyst a.

Grinding 10g of graphite oxide into powder, performing ultrasonic dispersion in deionized water for 3 hours, and then adding a certain amount of lanthanum phosphate, cerium phosphate and boron phosphate, wherein the lanthanum element in the lanthanum phosphate accounts for 5% of the mass of the graphite oxide, and the molar ratio of the lanthanum element to the cerium element to the boron element is 1: 0.1: 0.1, dropwise adding a sodium hydroxide solution until the pH value is 5, stirring uniformly, adding 20g of sodium borohydride, reacting for 12h at normal temperature, washing with an ethanol water solution, performing suction filtration, drying the obtained sample for 8h at 130 ℃, and then roasting in a muffle furnace at 300 ℃ for 8h to obtain the graphene-loaded lanthanum-cerium-boron catalyst b.

Grinding 10g of graphite oxide into powder, performing ultrasonic dispersion in deionized water for 2 hours, and then adding a certain amount of lanthanum phosphate, cerium phosphate and boron phosphate, wherein the lanthanum element in the lanthanum phosphate accounts for 8% of the mass of the graphite oxide, and the molar ratio of the lanthanum element to the cerium element to the boron element is 1: 0.25: 0.25, dropwise adding a sodium hydroxide solution until the pH value is 6, stirring uniformly, adding 20g of sodium borohydride, reacting at normal temperature for 12 hours, washing with an ethanol water solution, performing suction filtration, drying the obtained sample at 120 ℃ for 12 hours, and then roasting in a muffle furnace at 350 ℃ for 6 hours to obtain the graphene-loaded lanthanum-cerium-boron catalyst c.

Three, two bed catalyst packing

Filling the pretreated SAPO34 molecular sieve and the catalyst c into an upper bed layer and a lower bed layer of a fixed bed respectively according to the mass ratio of 1:1 to obtain a double-bed-layer catalyst A;

filling the catalyst c and the pretreated SAPO35 molecular sieve into an upper bed layer and a lower bed layer of a fixed bed respectively according to the mass ratio of 1:1 to obtain a double-bed catalyst B;

filling the pretreated SAPO11 molecular sieve and the catalyst a into an upper bed layer and a lower bed layer of a fixed bed respectively according to the mass ratio of 1:0.9 to obtain a double-bed catalyst C;

filling the pretreated SAPO44 molecular sieve and the catalyst b into an upper bed layer and a lower bed layer of a fixed bed respectively according to the mass ratio of 1:1.1 to obtain a double-bed catalyst D;

the total mass of the double-bed catalyst is 5.0g, and reaction raw materials are fed from the upper layer of the catalyst.

Example 2

Adopting a double-bed catalyst C, taking a mixed solution of pyrocatechol, methanol and trimethyl phosphate as a raw material, wherein the molar ratio of the pyrocatechol to the methanol is 1:3, the content of the trimethyl phosphate is 0.45 percent of the total mass of the pyrocatechol and the methanol, the reaction temperature is 280 ℃, the pressure is normal pressure, and the mass space velocity of the pyrocatechol is 0.1h^-1And after the raw material feeding is stabilized for 3 hours, analyzing the product by adopting gas chromatography.

Example 3

Adopting a double-bed catalyst D, wherein the raw material is a mixed solution of catechol, methanol and diethyl phosphate, the molar ratio of catechol to methanol is 1:10, the content of diethyl phosphate is 0.65 percent of the total mass of catechol and methanol, the reaction temperature is 260 ℃, the pressure is normal pressure, and the mass space velocity of catechol is 0.3h^-1And after the raw material feeding is stabilized for 3 hours, analyzing the product by adopting gas chromatography.

Example 4

Adopting a double-bed catalyst A, taking a mixed solution of catechol, methanol and phosphoric acid as a raw material, wherein the molar ratio of catechol to methanol is 1:5, the content of phosphoric acid is 0.55 percent of the total mass of catechol and methanol, the reaction temperature is 290 ℃, the pressure is normal pressure, and the mass space velocity of catechol is 0.2h^-1And after the raw material feeding is stabilized for 3 hours, analyzing the product by adopting gas chromatography.

Example 5

Adopting a double-bed catalyst B, wherein the raw material is a mixed solution of catechol, methanol and triethyl phosphate, the molar ratio of the catechol to the methanol is 1:7, the content of the triethyl phosphate is 0.60 percent of the total mass of the catechol and the methanol, the reaction temperature is 270 ℃, the pressure is normal pressure, and the mass space velocity of the catechol isIs 0.25h^-1And after the raw material feeding is stabilized for 3 hours, analyzing the product by adopting gas chromatography.

Comparative example 1

The main difference between comparative example 1 and example 4 is that the catalyst uses La of equal mass_0.5Ti_0.5The reaction conditions were the same as in example 4 except that P was replaced. The La_0.5Ti_0.5The preparation method of the P catalyst comprises the following steps: dissolving 15.58g of lanthanum nitrate in water, and adjusting the pH value to 10 by using ammonia water; sequentially adding 28.4g of titanium tetraisopropoxide and 8.3g of phosphoric acid, stirring for 6h at 96 ℃, then washing to be neutral by using deionized water, drying at 130 ℃, and roasting for 2h at 600 ℃ to finally obtain La_0.5Ti_0.5And (3) a P catalyst.

The conversion, veratrole selectivity and yield of catechol obtained in the above examples and comparative examples are shown in Table 1.

TABLE 1 yield and purity of veratrole catalyzed by catalyst in various examples

Examples/comparative examples	Conversion ratio of catechol%	Veratrole Selectivity%	Veratrole yield%
				Example 2	81.6	39.1	31.9
Example 3	54.7	41.0	22.4
				Example 4	91.6	38.4	35.2
Example 5	71.0	40.2	28.5
				Comparative example 1	79.4	19.8	15.7

As can be seen from Table 1, when the molar ratio of catechol to methanol was 1:5, the phosphoric acid content was 0.55% of the total mass of catechol and methanol, the reaction temperature was 290 ℃, the pressure was atmospheric pressure, and the mass space velocity of catechol was 0.2h^-1Under the conditions of (1), the conversion rate of catechol in the lanthanide catalyst of the comparative example was 79.4%, the selectivity of veratrole was 19.8%, and the yield of veratrole was 15.7%. The double-bed catalyst adopted by the invention shows higher veratrole selectivity and yield, and particularly under the condition of the embodiment 4, the reaction effect is optimal, the conversion rate of catechol is 91.6%, the selectivity of veratrole is 38.4%, and the yield of veratrole is 35.2%.

After the catalyst of example 4 is continuously used for 1000 hours, the conversion rate of catechol is only reduced to 95.7% of the initial conversion rate, the yield of veratrole is reduced to 94.4% of the initial yield, and the yield is still maintained to be more than 33.5%. The double-layer catalyst has good stability.