Titanium dioxide immobilized SO42-/ZrO2Catalyst, its preparation and use
阅读说明：本技术 一种二氧化钛固载SO42-/ZrO2催化剂及其制备和应用 (Titanium dioxide immobilized SO42-/ZrO2Catalyst, its preparation and use ) 是由 吴文良 尹新 杨江宇 严泽华 尹凯 徐伟伟 徐军 罗文利 陈国建 任应能 沈焕军 于 2021-10-09 设计创作，主要内容包括：本发明公开了一种二氧化钛固载SO-(4)～(2-)/ZrO-(2)催化剂及其制备和应用,属于多相催化技术领域,该二氧化钛固载SO-(4)～(2-)/ZrO-(2)催化剂,通过在无水乙醇中加入四叔丁氧基钛,氮气保护下搅拌再加入SBA-15分子筛,减压使乙醇完全挥发,样品研磨后煅烧冷却,用NaOH溶液反复洗涤,去离子水洗涤烘干后得到二氧化钛载体；在去离子水中,加入五水硝酸锆,使其充分溶解,再加入二氧化钛载体,搅拌将混合物烘干水分,预焙烧,预焙烧后样品置于H-(2)SO-(4)溶液中浸渍一定时间,抽滤煅烧,得介孔二氧化钛固载SO-(4)～(2-)/ZrO-(2)催化剂,催化剂催化性能良好,且能回收再用,还能避免产生废酸,有利于环境保护。(The invention discloses a titanium dioxide immobilized SO 4 2‑ /ZrO 2 A catalyst, a preparation method and an application thereof, belongs to the technical field of heterogeneous catalysis, and the titanium dioxide carries SO 4 2‑ /ZrO 2 Adding tetra-tert-butoxytitanium into absolute ethyl alcohol, stirring under the protection of nitrogen, adding an SBA-15 molecular sieve, decompressing to completely volatilize the ethyl alcohol, grinding a sample, calcining, cooling, repeatedly washing with NaOH solution, washing with deionized water and drying to obtain a titanium dioxide carrier; adding zirconium nitrate pentahydrate into deionized water to fully dissolve the zirconium nitrate pentahydrate, adding a titanium dioxide carrier, stirring to dry the mixture, pre-roasting, placing the pre-roasted sample in H 2 SO 4 Dipping in the solution for a certain time, filtering and calcining,obtaining mesoporous titanium dioxide immobilized SO 4 2‑ /ZrO 2 The catalyst has good catalytic performance, can be recycled, can avoid generating waste acid, and is beneficial to environmental protection.)
1. Titanium dioxide immobilized SO4 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: the method comprises the following steps:
step (1): adding titanium tetra-tert-butoxide into absolute ethyl alcohol, stirring under the protection of nitrogen, adding an SBA-15 molecular sieve, stirring at 25-50 ℃, reducing pressure until the ethyl alcohol is completely volatilized, grinding a sample, and calcining at 500-650 ℃; cooling to room temperature, repeatedly washing with NaOH solution to remove the SBA-15 template, washing with deionized water, and drying to obtain a titanium dioxide carrier;
step (2): adding zirconium nitrate pentahydrate into the deionized water washed in the step (1) to fully dissolve the zirconium nitrate pentahydrate, adding the titanium dioxide carrier prepared in the step (1), stirring, putting the mixture into a hot water bath to dry water, and pre-roasting at 110-130 ℃;
and (3): placing the sample pre-roasted in the step (2) in H2SO4Dipping in the solution, then carrying out suction filtration, and calcining at 500-650 ℃ to obtain the mesoporous titanium dioxide immobilized SO4 2-/ZrO2A catalyst.
2. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: the mass ratio of the tetra-tert-butoxytitanium to the SBA-15 molecular sieve in the step (1) is 1-3: 1.
3. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: in the step (1), the stirring time is 15-30 min under the protection of nitrogen, and the calcining time is 3-6 h.
4. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: in the step (1), the concentration of the NaOH solution is 1-3 mol/L, and the mass consumption of the NaOH solution is 6-10 times of that of the SBA-15 molecular sieve during each washing.
5. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: in the step (2), the mass ratio of the zirconium nitrate pentahydrate to the titanium dioxide carrier is 0.08-0.2: 1.
6. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: in the step (2), the mass consumption of the deionized water is 10-20 times of that of the titanium dioxide carrier.
7. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: in the step (2), the stirring time is 2-6 h, and the pre-roasting time is 8-16 h.
8. The titanium dioxide-supported SO according to claim 14 2-/ZrO2The preparation method of the catalyst is characterized by comprising the following steps: in the step (3), the concentration of the sulfuric acid is 0.3-0.7 mol/L, the mass amount of the sulfuric acid solution is 10-20 times of that of the pre-roasted sample, and the dipping time is 8-16 h.
9. A titania-supported SO prepared according to the method of any one of claims 1-84 2-/ZrO2A catalyst.
10. The titanium dioxide-supported SO of claim 94 2-/ZrO2The application of the catalyst in catalytic nitration reaction.
Technical Field
The invention relates to the technical field of heterogeneous catalysis, in particular to titanium dioxide immobilized SO4 2-/ZrO2The catalyst is heterogeneous catalyst and can be applied to catalyzing nitrification and denitrificationShould be used.
Background
Nitration is a reaction in which one or more nitro functional groups are introduced onto carbon atoms of an organic molecule, and nitro compounds, particularly nitroaromatics, are conveniently obtained by nitration. The nitroaromatic compound is an important fine chemical product and has wide application in the fields of medicines, pesticides, dyes, daily necessities, petrochemical industry and the like.
The aromatic compound is nitrated to obtain the nitroaromatic compound, and the commonly used nitrating agent is nitric acid. Generally, nitric acid is dissolved in sulfuric acid for nitration, and the nitration reaction of a nitric acid-sulfuric acid mixed acid system has the characteristics of high reaction speed and high nitration product yield, which is the most main method for industrially preparing the nitroaromatic compound. However, the disadvantages of the mixed nitric acid-sulfuric acid system are also obvious, on one hand, a large amount of waste acid and waste water are generated in the reaction, the environment is seriously polluted, and on the other hand, the selectivity of the nitration product is still to be improved. Therefore, research efforts have been ongoing around reducing environmental pollution caused by the nitration reaction and improving the selectivity of the nitrated product.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to:
(1) provides a titanium dioxide-immobilized SO4 2-/ZrO2A catalyst;
(2) a method for preparing the heterogeneous catalyst is provided;
(3) a method for using the heterogeneous catalyst prepared by the method for catalyzing nitration reaction is provided.
In order to solve the above problems, the present invention adopts the following technical solutions.
The invention aims to provide a titanium dioxide-immobilized SO4 2-/ZrO2The preparation method of the catalyst comprises the following steps:
step (1): adding titanium tetra-tert-butoxide into absolute ethyl alcohol, stirring under the protection of nitrogen, adding an SBA-15 molecular sieve, stirring at 25-50 ℃, reducing pressure until the ethyl alcohol is completely volatilized, grinding a sample, and calcining at 500-650 ℃; cooling to room temperature, repeatedly washing with NaOH solution to remove the SBA-15 template, washing with deionized water, and drying to obtain a titanium dioxide carrier;
step (2): adding zirconium nitrate pentahydrate into the deionized water washed in the step (1) to fully dissolve the zirconium nitrate pentahydrate, adding the titanium dioxide carrier prepared in the step (1), stirring, putting the mixture into a hot water bath to dry water, and pre-roasting at 110-130 ℃;
and (3): placing the sample pre-roasted in the step (2) in H2SO4Dipping in the solution, then carrying out suction filtration, and calcining at 500-650 ℃ to obtain the mesoporous titanium dioxide immobilized SO4 2-/ZrO2A catalyst.
Preferably, in the step (1), the mass ratio of the titanium tetra-tert-butoxide to the SBA-15 molecular sieve is 1-3: 1. The stirring time under the protection of nitrogen is preferably 15-30 min. The calcination time is preferably 3-6 h. Preferably, the concentration of the NaOH solution is 1-3 mol/L. The number of washing is preferably 3 to 5. The mass usage amount of the NaOH solution in each washing is preferably 6-10 times of that of the SBA-15 molecular sieve.
Preferably, in the step (2), the mass ratio of the zirconium nitrate pentahydrate to the titanium dioxide carrier is 0.08-0.2: 1. Preferably, the mass usage amount of the deionized water is 10-20 times of that of the titanium dioxide carrier. The stirring time is preferably 2-6 h. The pre-roasting time is preferably 8-16 h.
Preferably, in the step (3), the concentration of the sulfuric acid is preferably 0.3-0.7 mol/L. The mass usage amount of the sulfuric acid solution is preferably 10-20 times of that of the pre-roasted sample. The soaking time is preferably 8-16 h. The calcination time is preferably 3-7 h.
Preferably, the invention specifically recommends that the titanium dioxide is used for immobilizing SO4 2-/ZrO2The preparation method of the catalyst comprises the following steps: adding titanium tetra-tert-butoxide into absolute ethyl alcohol, stirring for 15-30 min under the protection of nitrogen, adding an SBA-15 molecular sieve, stirring at 25-50 ℃, decompressing until the ethyl alcohol is completely volatilized, grinding a sample, and calcining for 3-6 h at 500-650 ℃. After cooling to room temperature, using the molecular sieve with the mass 6-10 times of that of the SBA-15 molecular sieveWashing with 1-3 mol/L NaOH solution for 3-5 times, removing the SBA-15 template, washing with deionized water and drying to obtain a titanium dioxide carrier; adding zirconium nitrate pentahydrate into deionized water to be fully dissolved, adding the prepared titanium dioxide carrier, stirring for 2-6 h, putting the mixture into a hot water bath to dry water, and pre-roasting for 8-16 h at 110-130 ℃; placing the pre-roasted sample in H with the mass being 10-20 times of that of the sample and the concentration being 0.3-0.7 mol/L2SO4Dipping the solution for 8-16 h, filtering, and calcining at 500-650 ℃ for 3-7 h to obtain the titanium dioxide immobilized SO4 2-/ZrO2A catalyst; the mass ratio of the titanium tetra-tert-butoxide to the SBA-15 molecular sieve is 1-3: 1; the mass ratio of the zirconium nitrate pentahydrate to the titanium dioxide carrier is 0.08-0.2: 1; the mass of the deionized water for dissolving the zirconium nitrate pentahydrate is 10-20 times of that of the titanium dioxide carrier.
The second purpose of the invention is to provide a titanium dioxide-immobilized SO4 2-/ZrO2The catalyst is prepared by any one of the methods, and is used in the nitration reaction of chlorobenzene, and the result shows that the catalyst has good catalytic performance and can be conveniently recycled.
The third purpose of the invention is to provide a titanium dioxide-immobilized SO4 2-/ZrO2The application of the catalyst in catalytic nitration reaction, in particular to the nitration reaction of aromatic compounds.
Compared with the prior art, the invention has the advantages that:
the solid acid catalyst is used to replace the traditional sulfuric acid catalyst, so that the use of concentrated sulfuric acid is fundamentally avoided, waste acid is avoided, pollution caused by the waste acid is eliminated, and the environment protection is facilitated.
And (II) the selectivity of the product can be effectively improved.
And (III) the catalyst can be conveniently separated from the reaction system, and the catalyst can be reused.
Detailed Description
Example 1: SO immobilized on titanium dioxide4 2-/ZrO2Preparation of the catalyst
In 100 mL of anhydrous ethanol, 18.0g of tetra-tert-butoxytitanium was added, stirred for 15min under the protection of nitrogen, 6.0g of SBA-15 molecular sieve was added, the mixture was stirred at 40 ℃ and reduced in pressure until ethanol was completely volatilized, and the obtained sample was ground, transferred to a crucible, and calcined in a muffle furnace at 550 ℃ for 4 h. And cooling to room temperature, repeatedly washing for 4 times by using 2mol/L NaOH solution, wherein the using amount of the NaOH solution is 48g each time, completely removing the SBA-15 template, and washing and drying by using deionized water to obtain the titanium dioxide carrier.
3.86g of zirconium nitrate pentahydrate (9 mmol) is taken out of a beaker, 20 mL of deionized water is added and stirred to be fully dissolved, 3.2g of the prepared titanium dioxide carrier (60 mmol) is added and stirred for 4h, the mixture is put into a hot water bath to be dried, and the mixture is pre-roasted for 12h at 120 ℃.
3.0g of the above pre-calcined sample was placed in 45g of H of 0.5mol/L concentration2SO4Dipping the solution for 12h, filtering, calcining the solution for 5h at 550 ℃ to obtain the titanium dioxide immobilized SO4 2-/ZrO2A catalyst.
Example 2: SO immobilized on titanium dioxide4 2-/ZrO2Preparation of the catalyst
The preparation process is the same as that of example 1, the dosage of the zirconium nitrate pentahydrate is changed to 2.57g (6 mmol), the pre-roasting time is changed to 8h, and finally the titanium dioxide immobilized SO is obtained4 2-/ZrO2A catalyst.
Example 3: SO immobilized on titanium dioxide4 2-/ZrO2Preparation of the catalyst
The preparation process is the same as that of example 1, the dosage of the zirconium nitrate pentahydrate is changed to 5.15g (12 mmol), the pre-roasting time is changed to 16h, and finally the titanium dioxide immobilized SO is obtained4 2-/ZrO2A catalyst.
Example 4: SO immobilized on titanium dioxide4 2-/ZrO2Preparation of the catalyst
The preparation process was the same as example 1, except that 16g of tetra-tert-butoxytitanium was used, and the ethanol was completely volatilized at 40 deg.C under reduced pressure and normal temperature, to obtain SO-supported titanium dioxide4 2-/ZrO2A catalyst.
Example 5: SO immobilized on titanium dioxide4 2-/ZrO2Application of catalyst in nitration reaction
0.74g of titanium dioxide-supported SO was weighed4 2-/ZrO2The catalyst and 6.7g of fuming nitric acid (0.104 mol) were charged into a three-necked jacketed flask with a thermometer inserted, and stirred uniformly. Then, 10.6g of acetic anhydride (0.104 mol) is slowly dropped into the flask, and the temperature in the jacketed flask is controlled to be about 0 ℃. Within 1.5-2 h, 11.3g of chlorobenzene (0.1 mol) is dripped, and the temperature in the bottle is controlled to be about 0 ℃. After the dropwise addition, the reaction was continued for 1h at 0 ℃. The reaction was then heated to 50 ℃ and stirred for 4h, and samples were taken and monitored by GC, the results of which are shown in Table 1.
Table 1 Experimental results of catalysts in chlorobenzene nitration reaction in examples
Catalyst and process for preparing same
Chlorobenzene conversion (%)
P-chloronitrobenzene selectivity (%)
O-chloronitrobenzene selectivity (%)
Example 1
99.1
85.9
13.6
Example 2
98.2
80.6
18.9
Example 3
98.7
84.8
14.6
Example 4
99.0
83.5
15.4
Example 6: SO immobilized on titanium dioxide4 2-/ZrO2Application of catalyst in nitration reaction
The catalyst prepared in example 1 was used in the nitration of chlorobenzene, after the nitration was completed, the solid catalyst was separated by filtration and then reused in the nitration of chlorobenzene in the same manner as in example 5. Five recoveries gave the reaction results shown in table 2:
TABLE 2 recovery of titanium dioxide-bound SO4 2-/ZrO2Catalyst for nitration of chlorobenzene
Number of times of recovery
Chlorobenzene conversion (%)
P-chloronitrobenzene selectivity (%)
O-chloronitrobenzene selectivity (%)
1
99.2
85.8
13.7
2
99.0
85.5
13.9
3
98.7
85.1
14.3
4
98.4
84.7
14.7
5
98.1
84.4
14.9
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