CN110577470B - Method for catalyzing selective nitration of 2-naphthyl methyl ether by using zeolite molecular sieve - Google Patents
Method for catalyzing selective nitration of 2-naphthyl methyl ether by using zeolite molecular sieve Download PDFInfo
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Abstract
The invention discloses a method for catalyzing selective nitration of 2-naphthyl methyl ether by utilizing a zeolite molecular sieve, which comprises the following steps: s1: dissolving 6mmol of 2-naphthyl methyl ether in 10mL of dichloromethane, adding 5mL of acetic anhydride and 0.3 to 1.1g of zeolite molecular sieve catalyst, slowly adding 2mmol of aluminum nitrate under stirring, and stirring in a water bath at 25 ℃ for reaction for 12 hours; s2: after the reaction is finished, hydrolyzing acetic anhydride for 1h at 40 ℃; s3: after the hydrolysis is completed, extracting, washing and drying the solution obtained in the S2 after the reaction; s4: rotary evaporation to make it evaporate and crystallize to obtain crude extract. The zeolite molecular sieve is used for catalyzing selective nitration reaction of 2-naphthyl methyl ether for the first time, the ZSM-5 zeolite molecular sieve is selected to have the most obvious catalytic effect, when the ZSM-5 catalyst is 0.9g, the substrate conversion rate is higher and reaches 93.98%, the yield is 77.09%, and the isomerization ratio reaches 6.05%.
Description
Technical Field
The invention belongs to the field of fine chemical engineering, and particularly relates to a method for catalyzing selective nitration of 2-naphthyl methyl ether by using a zeolite molecular sieve.
Background
The products of the primary nitration of 2-naphthyl methyl ether comprise 1-nitro-2-naphthyl methyl ether and 3-nitro-2-naphthyl methyl ether, wherein the 1-nitro-2-naphthyl methyl ether is an intermediate of a plurality of organic syntheses and can be used for synthesizing medical drugs, pesticides, chemicals and dyes. With the development of aromatic nitration reaction research, high regioselective green nitration in non-acidic systems has become the main research direction of nitration researchers. Therefore, how to make the 2-naphthyl methyl ether generate nitro substitution at the alpha position to realize the green nitration with regioselectivity is a key means for improving the yield of the 1-nitro-2-naphthyl methyl ether and reducing byproducts.
The 2-naphthyl methyl ether nitration mechanism related by the scheme is as follows:
1) The reaction mechanism of nitrating 2-naphthyl methyl ether by a nitric acid/acetic anhydride system is as follows: in the reaction process, nitric acid and acetic anhydride firstly react to generate acetyl nitrate, and the substance is easily decomposed and activated into NO 2 + and NO 3 - ，NO 2 + Can partially attack aromatic hydrocarbon to generate nitration products, and the specific reaction process is as follows:
2) The reaction mechanism of the metal nitrate/acetic anhydride system nitration 2-naphthyl methyl ether is as follows: the metal nitrate can be decomposed into NO 2 The free radical is used for attacking some active aromatic hydrocarbons to generate products, and the specific reaction process is as follows:
the methoxy in the raw material is an o-para positioning group, when the methoxy is positioned on beta, the nitro is mainly positioned on alpha, so that the product is mainly 1-nitro-2-naphthyl methyl ether.
The method uses the zeolite molecular sieve for catalyzing the selective nitration of 2-naphthyl methyl ether for the first time, utilizes a nitric acid agent/acetic anhydride system to nitrify 1-methoxynaphthalene, and adopts a controlled variable method to explore the influence of different types of zeolite molecular sieve catalysts, the catalyst dosage and the catalyst recovery times on the selective nitration of 1-methoxynaphthalene.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method for catalyzing selective nitration of 2-naphthyl methyl ether by using a zeolite molecular sieve so as to realize high-selectivity nitro substitution of the 2-naphthyl methyl ether at an alpha position, further improve the yield of 1-methoxyl-4-nitronaphthalene and reduce side reactions. .
The technical scheme of the invention is summarized as follows:
a method for catalyzing selective nitration of 2-naphthyl methyl ether by utilizing zeolite molecular sieve comprises the following steps:
s1: putting 6mmol 2-naphthyl methyl ether into a dry 50mL round bottom flask, adding 10mL dichloromethane, slowly dissolving at 10 ℃ and low temperature, adding 5mL acetic anhydride after complete dissolution, shaking to completely mix, adding 0.3-1.1 g zeolite molecular sieve catalyst, slowly adding aluminum nitrate under stirring, and controlling the molar ratio of the 2-naphthyl methyl ether to the nitrate radical to be 1: stirring in water bath at 1,25 ℃ for reaction for 12h;
s2: after the reaction is finished, recovering the catalyst, adding 20mL of deionized water into the reaction system, heating to 40 ℃, and continuing the reaction for 1h to fully hydrolyze acetic anhydride into acetic acid;
s3: after the hydrolysis is completed, extracting, washing and drying the solution obtained in the S2 after the reaction;
s4: evaporating dichloromethane in the solution product obtained in the step S3 by using a rotary evaporator, evaporating and crystallizing the dichloromethane to obtain a crude extract, weighing the crude extract, and calculating the conversion rate, the yield and the isomerization ratio, wherein the conversion rate of the raw material reaches 85.20-100%, the yield reaches 69.88-82.02%, and the isomerization ratio reaches 1.56-6.09.
Preferably, the zeolite molecular sieve catalyst comprises a beta-25 type zeolite molecular sieve, a beta-60 type zeolite molecular sieve, a SAPO-11 type zeolite molecular sieve, a ZSM-5 type zeolite molecular sieve, a NaY type zeolite molecular sieve, siO 2 /Al 2 O 3 One or more of zeolite-type molecular sieves.
A method for catalyzing selective nitration of 2-naphthyl methyl ether by utilizing a zeolite molecular sieve comprises the following steps:
s1: putting 6mmol 2-naphthyl methyl ether into a dry 50mL round bottom flask, adding 10mL dichloromethane, slowly dissolving at 10 ℃ and low temperature, adding 5mL acetic anhydride after complete dissolution, shaking to completely mix, adding 0.9g ZSM-5 zeolite molecular sieve catalyst, slowly adding aluminum nitrate under stirring, and controlling the molar ratio of the 2-naphthyl methyl ether to the nitrate radical to be 1: stirring in water bath at 1,25 ℃ for reaction for 12h;
s2: after the reaction is finished, recovering the catalyst, adding 20mL of deionized water into the reaction system, heating to 40 ℃, and continuing the reaction for 1h to fully hydrolyze acetic anhydride into acetic acid;
s3: after the hydrolysis is completed, extracting, washing and drying the solution obtained in the S2 after the reaction;
s4: evaporating dichloromethane in the solution product obtained in the step S3 by using a rotary evaporator, evaporating and crystallizing the dichloromethane to obtain a crude extract, weighing the crude extract, and calculating the conversion rate, the yield and the isomerization ratio, wherein the conversion rate of the raw material reaches 93.98%, the yield reaches 77.09% and the isomerization ratio reaches 6.05.
Preferably, the catalyst recovery method specifically comprises: standing the solution after the reaction of the S2 for 24h, carrying out solid-liquid separation, washing the catalyst at the bottom by using distilled water and dichloromethane for 3 times respectively, and then putting the washed catalyst into a forced air drying oven to dry for 24h; when the catalyst is used again, the dried catalyst is calcined in a muffle furnace at 550 ℃ for at least 6 hours, and the recovery and reuse times of the catalyst are more than or equal to 3 times.
Preferably, the extraction, washing and drying processes are specifically as follows: after acetic anhydride is completely hydrolyzed, adding 10mL of dichloromethane into a round-bottom flask, oscillating for dissolving, extracting, pouring into a separating funnel, oscillating, standing and separating a lower layer solution, continuously adding 10mL of dichloromethane into an upper layer solution for separating, washing and separating the lower layer solution twice with 20mL of deionized water, adding 25mL of saturated sodium carbonate solution for alkali washing, washing and separating with 20mL of deionized water for 3 times, adding 2g of anhydrous sodium sulfate to make the obtained organic phase sand, and drying for 24 hours.
Preferably, the rotary evaporator has an evaporation temperature of 60 ℃ and a rotation rate of 30r/min.
The invention has the beneficial effects that:
1. the zeolite molecular sieve is used for catalyzing selective nitration of 2-naphthyl methyl ether for the first time, the ZSM-5 zeolite molecular sieve is selected to have the most obvious catalytic effect, which is related to the unique space pore channel structure and the hydrothermal stability of the ZSM-5 zeolite molecular sieve, when the ZSM-5 catalyst is 0.9g, the substrate conversion rate is higher and reaches 93.98%, the yield is 77.09%, the selectivity is also improved, the isomerization ratio reaches 6.05%, and the yield of 1-nitro-2-naphthyl methyl ether is obviously improved. The zeolite molecular sieve catalyst has a very regular crystal linear structure and has 'pore channels' similar to naphthalene molecules in size, the 'pore channels' enable the catalyst to have very high internal surface area and catalytic activity, and when a nitrating agent enters the inside of the molecular sieve, acid sites on the surfaces of the 'pore channels' form nitroxyl cations; in addition, zeolite molecular sieve catalysts with different pore sizes can allow substances smaller than the pore size to pass through, while substances without such a structure are blocked on the surface of the catalyst, so that the molecular sieve catalysts have special selective catalytic capability.
2. The zeolite molecular sieve catalyst can be repeatedly recycled for more than three times, and the activity and the surface property of the catalyst are not obviously changed.
3. The invention takes zeolite molecular sieve as a catalyst, adopts a nitrating agent acetic anhydride nitration system with mild nitration capability to catalyze the selective nitration of 2-naphthyl methyl ether, and avoids the defects of environmental pollution and poor regional selectivity caused by using a mixed acid system.
Drawings
FIG. 1 is a N2 adsorption-desorption isotherm of a ZSM-5 zeolite molecular sieve catalyst;
FIG. 2 is a pore size distribution curve of adsorption-desorption of ZSM-5 zeolite molecular sieve based catalyst N2;
FIG. 3 is a FT-IR analysis of a ZSM-5 zeolite molecular sieve catalyst in which (a) fresh catalyst, (b) recovered catalyst, (c) regenerated catalyst;
FIG. 4 is an XRD analysis of a ZSM-5 zeolite molecular sieve catalyst in which (a) fresh catalyst, (b) recovered catalyst, and (c) regenerated catalyst;
FIG. 5 is a TG plot of a recovered ZSM-5 zeolite molecular sieve;
FIG. 6 is a flow chart of the method of the present invention.
Detailed Description
The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.
EXAMPLES 1-5 exploring the optimum nitrating agent for nitration of 2-Naphthalenethyl Ether
Under the same other reaction conditions, different kinds of nitrating agents were added to carry out comparative experiments. The nitrating agents corresponding to examples 1 to 5 were aluminum nitrate, bismuth nitrate, magnesium nitrate, ferric nitrate, fuming nitric acid in this order, and the test methods were as follows:
6mmol of 2-naphthyl methyl ether, 10mL of dichloromethane and 5mL of acetic anhydride are sequentially weighed and put into a 50mL round-bottom flask to be completely mixed by oscillation, aluminum nitrate/bismuth nitrate/magnesium nitrate/ferric nitrate/fuming nitric acid are slowly added into the flask under the stirring state, and the molar ratio of the 2-naphthyl methyl ether to the nitrate is controlled to be 1:1, then placing the flask into a water bath with constant temperature of 25 ℃ and heat collection type heating stirrer for reaction for 12 hours.
Product post-treatment:
1) Hydrolysis, extraction, washing and drying: after acetic anhydride is completely hydrolyzed, adding 10mL of dichloromethane into a round-bottom flask, oscillating for dissolving, extracting, pouring into a separating funnel, oscillating, standing, separating a lower layer liquid, continuously adding 10mL of dichloromethane into the upper layer liquid for separating, washing and separating the lower layer liquid twice with 20mL of deionized water, adding 25mL of saturated sodium carbonate solution for alkali washing, washing and separating with 20mL of deionized water for 3 times, adding 2g of anhydrous sodium sulfate to enable the obtained organic phase to be sand-shaped, and drying for 24 hours.
2) Gas chromatography analysis: placing 2mL of dried product solution in sample bottles, sequencing the sample bottles, placing the sample bottles on an automatic sample injector, detecting the samples by using a PANNA 95 automatic sample injection gas chromatograph and a CATALOG 19091J-413 30mX0.320 mm chromatographic column, setting the temperature of a sample inlet to be 250 ℃, the split ratio to be 10, setting the temperature of a detector to be 250 ℃, and setting the temperature of the detector to be 10 2 The flow rate of (2) is 50.0mL/min, the flow rate of air is 250.0mL/min, the sample injection amount is 1 μ L, the initial temperature is 120 ℃, the holding time is 1min, the first-stage temperature is 180 ℃, the heating rate is 10 ℃/min, the holding time is 1min, the second-stage temperature is 240 ℃/min, and the holding time is 5min. The appropriate reaction conditions are selected according to the peak pattern displayed by the gas chromatograph and the content of each substance in the data recording solution.
3) Separation and purification: evaporating dichloromethane in the dried solution by using a rotary evaporator, evaporating and crystallizing to obtain a crude extract, setting the evaporation temperature to be 60 ℃ and the rotation rate to be 30r/min, then weighing, and calculating the conversion rate, the yield and the isomerization ratio.
The yield calculation method comprises the following steps: calculating the yield of each product according to the content of each component measured in the gas chromatograph by using the following formula:
wherein, ω is 1 Content of ingredient in the product
m 1 Actual production
m 0 Theoretical yield
Table 1 shows the effect of different nitrating agents on the selective nitration of 2-naphthyl methyl ether
TABLE 1 Effect of nitrating agent species on Selective nitration of 2-Naphthalenethyl Ether
The data in table 1 show that the conversion of aluminum nitrate is highest and the yield is also highest. Bismuth nitrate has the highest isomerization ratio, but the conversion and yield are very low. The isomerization ratio of other nitrating agents is higher than that of aluminum nitrate, but the conversion and yield are lower than that of aluminum nitrate. According to the comprehensive consideration of the conversion rate and the yield, aluminum nitrate is selected as a nitrating agent for the next reaction.
Examples 6 to 9 study the optimum molar ratio of 2-naphthylmethyl ether to nitrate in the nitration of 2-naphthylmethyl ether
On the basis of obtaining the optimal nitrating agent, the molar ratio of the 2-naphthyl methyl ether to the nitrate radical dosage is changed. The molar ratio of 2-naphthyl methyl ether to nitrate used in example 1 is 1.
Table 2 shows the influence of different molar ratios of 2-naphthylmethyl ether to nitrate on the selective nitration of 2-naphthylmethyl ether
TABLE 2 Effect of different molar ratios on 2-Naphthalenethyl Ether nitration Selectivity
As can be seen from the data in the above Table 2, the yield, conversion rate and isomerization ratio in the reaction result are increased with the increase of the amount of the nitrating agent, which indicates that the nitration reaction is more complete with the increase of the amount of the nitrating agent, but for better exploration of the influence of temperature, time and catalyst on the nitration selectivity of 2-naphthylmethyl ether, the following examples all adopt a molar ratio of 2-naphthylmethyl ether/nitrate of 1:1 under the condition of 1.
Examples 10 to 12 investigation of the optimum reaction temperature for the nitration of 2-naphthylmethyl ether
The reaction temperature of the system was varied according to the conditions determined above. The reaction temperature for example 1 was 25 ℃ and the reaction temperatures for examples 10 to 12 were 5 ℃, 15 ℃ and 35 ℃ in this order, and the test methods were as follows:
weighing 6mmol of 2-naphthyl methyl ether, 10mL of dichloromethane and 5mL of acetic anhydride in turn, putting the mixture into a 50mL round-bottom flask, oscillating the mixture to be completely mixed, slowly adding aluminum nitrate into the flask under the stirring state, and controlling the molar ratio of the 2-naphthyl methyl ether to the nitrate radical to be 1:1, then placing the flask into a water bath heat collection type heating stirrer with the constant temperature of 5 ℃/15 ℃/35 ℃ for reaction for 12 hours.
The product work-up was the same as in examples 1 to 5.
Table 3 shows the effect of different temperatures on the selective nitration of 2-naphthylmethyl ether
TABLE 3 Effect of different temperatures on the Selective nitration of 2-Naphthalenethyl Ether
From the data in Table 3 above, it can be seen that the nitrating agent is aluminum nitrate and the molar ratio of aluminum nitrate to 2-naphthyl methyl ether to nitrate is 1:1. time, solvent, etc. are not changed. The reaction is very weak at 5 ℃, the conversion rate is only 9.31 percent, and the reaction is not suitable for the nitration reaction under the condition; the conversion rate is increased along with the increase of the temperature, but the higher the temperature is, the more the reaction is in the direction of increasing the conversion rate; the conversion rate is highest when the temperature reaches 25 ℃, and reaches 91.93 percent; the conversion rate decreases somewhat when the temperature continues to rise to 35 ℃. It can be seen that the temperature has a strong influence on the reaction, and that both too high and too low temperatures are detrimental to the formation of the product. The data show that the optimum temperature is 25 ℃.
Examples 13 to 18 study of the influence of different kinds of zeolite molecular sieve catalysts on the selective nitration of 2-naphthylmethyl ether
According to the determined optimal conditions, different kinds of zeolite molecular sieve catalysts are respectively added into the reaction system, and the influence of the different kinds of zeolite molecular sieve catalysts on the reaction is researched. The catalysts corresponding to the embodiments 13 to 18 are beta-60, SAPO-11, ZSM-5, naY and SiO 2 /Al 2 O 3 Beta-25 catalyst, test method as follows:
6mmol of 2-naphthylmethyl ether, 10mL of dichloromethane and 5mL of acetic anhydride are weighed in turn and put into a 50mL round-bottom flask to be shaken for complete mixing, and then 0.5g of beta-60/SAPO-11/ZSM-5/NaY/SiO is added into the flask respectively 2 /Al 2 O 3 The catalyst is/beta-25, aluminum nitrate is slowly added into a flask under the stirring state, and the molar ratio of 2-naphthyl methyl ether to nitrate radical is controlled to be 1:1, putting the flask into a thermostatic water bath heat collection type heating stirrer at the temperature of 25 ℃ for reaction for 12 hours.
Product work-up was the same as in examples 1 to 5, except that catalyst recovery was carried out prior to hydrolysis of acetic acid, as follows: after the reaction is finished, standing the solution for 24h, carrying out solid-liquid separation, washing the catalyst at the bottom by using distilled water and dichloromethane for 3 times respectively, and then putting the washed catalyst into a forced air drying oven to dry for 24h; when the catalyst is used again, the dried catalyst is calcined in a muffle furnace at 550 ℃ for at least 6 hours, and the recovery and reuse times of the catalyst are more than or equal to 3 times.
Table 4 shows the effect of different zeolite molecular sieve catalysts on the selective nitration of 2-naphthyl methyl ether
TABLE 4 influence of different catalysts on the Selective nitration of 2-Naphthalenethyl Ether
As can be seen from the data in Table 4, the zeolite molecular sieves beta-25 and beta-60 have very good catalytic effects, completely disappear substrates, and completely proceed the reaction, but the isomerization ratios of the two catalysts are too low to be beneficial to the generation of a mononitration product, wherein the ZSM-5 catalyst has very obvious catalytic effects and the highest isomerization ratio, and the ZSM-5 zeolite molecular sieve has a unique spatial pore structure and hydrothermal stability. In comprehensive consideration, the ZSM-5 catalyst is selected optimally.
Examples 19 to 22 study the influence of different amounts of zeolite molecular sieve catalysts on the selective nitration of 2-naphthylmethyl ether
According to the determined conditions, ZSM-5 catalysts with different masses are added into the reaction system, and the influence of the catalyst dosage on the nitration reaction of the 2-naphthyl methyl ether is researched. The amount of the catalyst used in example 15 was 0.5g, and the amounts of the catalysts used in examples 21 to 26 were 0.3g, 0.7g, 0.9g and 1.1g, respectively, and the test methods and product workup were the same as in examples 13 to 18.
Table 5 shows the effect of different amounts of zeolite molecular sieve catalyst on the selective nitration of 2-naphthylmethyl ether
TABLE 5 influence of different amounts of catalyst on the Selective nitration of 2-Naphthalenethyl Ether
It can be seen from the data in table 5 that although the amount of ZSM-5 catalyst used was changed, the changes in conversion, yield and isomerization ratio were not significant. However, at 0.9g of ZSM-5 catalyst, the conversion and yield were slightly higher than the other amounts, so 0.9g of catalyst was chosen for the convenience of carrying out subsequent catalyst recovery experiments.
Examples 23 to 25 study on the influence of the number of times of recovery of zeolite molecular sieve catalyst on the selective nitration of 2-naphthylmethyl ether
According to the determined optimal conditions, ZSM-5 zeolite molecular sieve catalysts with recovery times are respectively added into the reaction system, and the influence of the recovery times of the zeolite molecular sieve catalysts on the reaction is researched. The catalyst recovery times for examples 23 to 25 were 1, 2, and 3 times in this order, and the test methods were as follows:
6mmol of 2-naphthyl methyl ether, 10mL of dichloromethane and 5mL of acetic anhydride are sequentially weighed and put into a 50mL round-bottom flask to be shaken and completely mixed, then 0.9g of ZSM-5 catalyst recovered for the first time/the second time/the third time is respectively added into the flask, and aluminum nitrate is slowly added into the flask under the stirring state, wherein the molar ratio of the 2-naphthyl methyl ether to the aluminum nitrate is 1:1, then placing the flask into a water bath with constant temperature of 25 ℃ and heat collection type heating stirrer for reaction for 12 hours.
Table 6 shows the effect of the ZSM-5 catalyst recovery times on the selective nitration of 2-naphthylmethyl ether
TABLE 6 influence of catalyst recycle and regeneration times on 2-naphthyl methyl ether selective nitration
As can be seen from Table 6, the catalytic results of three times of catalyst recovery are very small compared with those of the fresh catalyst, indicating that the ZSM-5 catalyst can be recycled at least three times in the aluminum nitrate/acetic anhydride system.
Examples 26 to 29 characterization and examination of ZSM-5 zeolite molecular sieves
Example 26N treatment of ZSM-5 zeolitic molecular sieves 2 Adsorption-desorption analysis
1)N 2 Adsorption-desorption analysis method and detection conditions: 0.1g of ZSM-5 zeolite molecular sieve catalyst is taken to be fresh, the uncalcined sample is recovered, the calcined and regenerated sample is recovered and placed in a sample tube, the sample is degassed for 12 hours in the instrument at 150 ℃, and then the sample detection is carried out in a specific surface area determinator.
2)N 2 Adsorption-desorption analysis results: FIG. 1 is a diagram of the N of a ZSM-5 zeolite molecular sieve 2 Adsorption-desorption isotherms, fig. 2 is a pore size distribution curve of the ZSM-5 zeolite molecular sieve, fig. 1 corresponds to fig. 2, and table 7 is a pore size distribution table of the ZSM-5 zeolite molecular sieve.
TABLE 7 pore size distribution Table for ZSM-5 zeolite molecular sieves
As can be seen from an analysis of the data in FIGS. 1-2 and Table 7, the specific surface area of the ZSM-5 catalyst after use is significantly reduced from the previous 356m 2 The ratio of/g to 297m 2 Per g, its pore volume also varied widely from 0.756cm 3 The/g is reduced to 0.609cm 3 The analysis is that the ZSM-5 catalyst adsorbs other products in the reaction system, and the materials in the reaction system cannot be dissociated by washing, so that the specific surface area and the pore volume of the ZSM-5 catalyst are reduced; the various characteristics of the calcined ZSM-5 catalyst and the fresh catalyst are slightly reduced, but the basic difference is not large, and the main reason of the method is probably that the calcination decomposes unwashed substances; but minor changes were made due to the acidic reaction environment which allowed the ZSM-5 catalyst to migrate through the silicon and deform or collapse the framework.
Example 27 FT-IR analysis of ZSM-5 zeolitic molecular sieves
1) FT-IR analysis method and detection conditions: a Fourier transform infrared spectrometer is adopted to perform performance analysis on a ZSM-5 zeolite molecular sieve catalyst which is fresh, recycled without calcination and recycled after calcination regeneration, KBr is put into an infrared oven to be roasted for 20min and then taken out, the KBr and the sample are uniformly mixed according to the proportion of 100, and then the mixture is ground in an agate mortar for 10min, sieved and tabletted. Setting the detection wavelength to 4000cm in the mid-infrared region -1 ～400cm -1 The sample transmittance was measured.
2) FT-IR analysis results: different ZSM-5 zeolite molecular sieve catalysts at 4000cm -1 -400cm -1 The IR spectra in the range are shown in FIG. 3, wherein (a) fresh catalyst, (b) recovered catalyst, and (c) regenerated catalyst. As can be seen from the figure, the ZSM-5 catalyst absorbs a trace amount of substances in the reaction system, so that the infrared spectrum of the catalyst has little difference; the recovered ZSM-5 catalyst (b) showed two new peaks respectively located at 1414cm on the spectrogram compared with the fresh catalyst (a) -1 And 1741cm -1 Wherein the former peak corresponds to the nitroaromatic compound and the latter corresponds to the carbonyl peak, and the analysis should be acetic acid; after the ZSM-5 catalyst is calcined in a muffle furnace at 550 ℃ for 6 hours, the adsorbed trace substances are dissociated, and the catalytic activity is recovered, which is shown in the difference between the regenerated spectrogram (c) and the fresh spectrogram (a)Are small.
EXAMPLE 28 XRD analysis of ZSM-5 Zeolite molecular sieves
1) XRD analysis method and detection conditions: an X-ray diffractometer is used for detecting samples of the ZSM-5 zeolite molecular sieve catalyst which are fresh, recycled without calcination and recycled after calcination, the voltage is set to be 20kV, the current is set to be 30mA, DS = SS =1 DEG, RS =0.2 DEG, the scanning angle of the instrument is 5-60 DEG, and the scanning step is 0.02 deg.
2) XRD analysis result: FIG. 4 is an XRD analysis of a ZSM-5 zeolite molecular sieve catalyst having (a) fresh catalyst, (b) recovered catalyst, and (c) regenerated catalyst. As can be seen from FIG. 4, the fresh ZSM-5 catalyst has characteristic peaks at 2 theta angles of 10.22 degrees, 16.9 degrees, 22.4 degrees and 24.22 degrees. After the catalyst is recovered and calcined in a muffle furnace at 550 ℃ for 6 hours, the difference between the intensity and the position of a characteristic peak and the ratio of the characteristic peak to the fresh catalyst is small, which shows that the crystal characteristic change of the regenerated ZSM-5 catalyst can be ignored, the three-dimensional space structure of the catalyst is not damaged, and the catalytic performance is basically the same as that of the fresh catalyst.
EXAMPLE 29 thermogravimetric analysis of ZSM-5 zeolite molecular sieve
1) Thermogravimetric analysis method and detection conditions: and (3) putting the recovered 15mg of ZSM-5 zeolite molecular sieve sample into a corundum crucible, setting the initial temperature to be 25 ℃, the final temperature to be 600 ℃, heating at the speed of 5 ℃/min, and performing thermogravimetric analysis (TGA) by using a microcomputer differential thermal balance.
2) Thermogravimetric analysis results: FIG. 5 is a TG diagram of a recovered ZSM-5 zeolite molecular sieve, and it can be seen from FIG. 5 that the recovered ZSM-5 catalyst has a slight weight loss phenomenon at 25-600 ℃, mainly because the ZSM-5 catalyst is a porous material, and can absorb water molecules free in the air and a small amount of organic substances in the reaction.
While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.
Claims (4)
1. A method for catalyzing selective nitration of 2-naphthyl methyl ether by utilizing a zeolite molecular sieve is characterized by comprising the following steps:
s1: putting 6mmol of 2-naphthyl methyl ether into a dry 50mL round-bottom flask, adding 10mL of dichloromethane, slowly dissolving at the low temperature of 10 ℃, adding 5mL of acetic anhydride after complete dissolution, shaking to completely mix the acetic anhydride, adding 0.9g of ZSM-5 zeolite molecular sieve catalyst, slowly adding aluminum nitrate under the stirring state, and controlling the molar ratio of the 2-naphthyl methyl ether to the nitrate radical to be 1: stirring in water bath at 1,25 ℃ for reaction for 12h;
s2: after the reaction is finished, recovering the catalyst, adding 20mL of deionized water into the reaction system, heating to 40 ℃, and continuing the reaction for 1h to fully hydrolyze acetic anhydride into acetic acid;
s3: after the hydrolysis is completed, extracting, washing and drying the solution obtained in the S2 after the reaction;
s4: evaporating dichloromethane in the solution product obtained in the step S3 by using a rotary evaporator, evaporating and crystallizing the dichloromethane to obtain a crude extract, weighing the crude extract, and calculating the conversion rate, the yield and the isomerization ratio, wherein the isomerization ratio is the content ratio of 1-nitro-2-naphthyl methyl ether to 3-nitro-2-naphthyl methyl ether, the conversion rate of the raw material reaches 93.98%, the yield reaches 77.09%, and the isomerization ratio reaches 6.05.
2. The method for catalyzing selective nitration of 2-naphthyl methyl ether by utilizing zeolite molecular sieve according to claim 1, wherein the catalyst recovery method specifically comprises: standing the solution after the reaction of the S2 for 24h, carrying out solid-liquid separation, washing the catalyst at the bottom by using distilled water and dichloromethane for 3 times respectively, and then putting the washed catalyst into a forced air drying oven to dry for 24h; when the catalyst is used again, the dried catalyst is calcined in a muffle furnace at 550 ℃ for at least 6h, and the recovery and reuse times of the catalyst are more than or equal to 3.
3. The method for catalyzing selective nitration of 2-naphthyl methyl ether by using zeolite molecular sieve according to claim 1, wherein the processes of extracting, washing and drying are as follows: after acetic anhydride is completely hydrolyzed, adding 10mL of dichloromethane into a round-bottom flask, oscillating for dissolving, extracting, pouring into a separating funnel, oscillating, standing and separating a lower layer solution, continuously adding 10mL of dichloromethane into an upper layer solution for separating, washing and separating the lower layer solution twice with 20mL of deionized water, adding 25mL of saturated sodium carbonate solution for alkali washing, washing and separating with 20mL of deionized water for 3 times, adding 2g of anhydrous sodium sulfate to make the obtained organic phase sand, and drying for 24 hours.
4. The method for catalyzing selective nitration of 2-naphthyl methyl ether by using zeolite molecular sieve as claimed in claim 1, characterized in that evaporation temperature of the rotary evaporator is 60 ℃ and rotation speed is 30r/min.
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