CN115739176A - Preparation method of vacancy polyacid-based ionic liquid supported catalyst, product and application of product - Google Patents

Abstract

The invention discloses a preparation method of a vacancy polyacid based ionic liquid supported catalyst, a product and application thereof. The method has simple operation process, adopts heterogeneous catalyst, is easy to recover, and has better oxidation removal effect on thiophene sulfides in oil products. In particular, for dibenzothiophene, a small amount of hydrogen peroxide (H) is used ₂ O ₂ 30 wt%) as an oxidizing agent, can realize high-efficiency and rapid desulfurization under mild conditions. The catalyst has the characteristics of high catalytic efficiency, stable structure, good circulation stability and the like.

Description

A kind of preparation method and product of vacant multi-acid-based ionic liquid supported catalyst and its its application

technical field

The invention belongs to the field of material preparation and catalytic reaction, and specifically relates to a preparation method, product and application of a lack of polyacid-based ionic liquid-supported catalyst.

Background technique

With the continuous development of social modernization, the improper discharge of sulfur oxides (SOx) and sulfate particles from the combustion of a large number of sulfur-containing fuels has caused serious air pollution and acid rain, which has caused huge harm to human health. harm.

Therefore, improving fuel quality, producing clean fuel, and reducing sulfur emissions are one of the focuses of global attention. At present, domestic and foreign desulfurization processes mainly include hydrodesulfurization (HDS), oxidative desulfurization (ODS), extractive desulfurization (EDS), adsorption desulfurization (ADS) and other methods. Among them, the traditional hydrodesulfurization (HDS) technology is limited due to the need to consume a large amount of hydrogen, the harsh reaction conditions and the large investment in equipment, and it is difficult to remove thiophene sulfides in fuels, so it is not suitable for the current ultra-low fuel desulfurization goals. Oxidative desulfurization (ODS) is favored by people as a simple, efficient and most promising desulfurization technology because of its milder reaction conditions and no need to consume expensive hydrogen in the reaction process.

Polyoxometalates (POMs), as a class of metal oxide clusters, have great application potential in catalysis due to their rich structures and excellent redox properties. At the same time, their unique acidic, multifunctional and "pseudo-liquid phase" behaviors can be shown under mild conditions, and their acidic and redox properties can be adjusted in a wide range by changing their chemical composition. The advantages enable POMs to be used as solid acid catalysts and electron transfer catalysts in the study of catalytic oxidation desulfurization properties. For example, patent CN 113083368 A proposes a metal-organic framework-supported heteropolyacid oxidation desulfurization catalyst.

However, problems such as low specific surface area and easy solubility in organic solvents have limited the further application of polyoxometalates in oxidative desulfurization reactions.

Therefore, it is of great significance to develop a heterogeneous catalyst that can effectively improve its specific surface area and chemical stability under the premise of ensuring the oxidation activity of vacant polyacids.

Contents of the invention

The purpose of this section is to outline some aspects of embodiments of the invention and briefly describe some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and titles of this application, to avoid obscuring the purpose of this section, the abstract and titles, and such simplifications or omissions should not be used to limit the scope of the invention.

In view of the problems mentioned above and/or in the prior art, the present invention is proposed.

Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of a vacant polyacid-based ionic liquid-supported catalyst.

In order to solve the above-mentioned technical problems, the present invention provides the following technical scheme: a preparation method of a vacant polyacid-based ionic liquid-supported catalyst, comprising:

Preparation of vacant polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O;

Using ion exchange to obtain polyacid-based ionic liquid POMs-IL;

The vacant polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ was obtained by impregnation method.

As a preferred scheme of the preparation method of the vacant polyacid-based ionic liquid-supported catalyst of the present invention, wherein: the vacant polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O, which Preparation methods include,

Dissolve sodium tungstate in water and stir until the solid is completely dissolved;

Then add phosphoric acid dropwise to adjust the pH to 8.9-9.0, then add glacial acetic acid dropwise under stirring to produce a large amount of white precipitate, and finally measure the pH of the solution to be 7.5±0.3. ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O.

As a preferred solution of the preparation method of the vacant polyacid-based ionic liquid-supported catalyst of the present invention, wherein: the molar ratio of sodium tungstate to phosphoric acid is 6:1.

As a preferred version of the preparation method of the deficient polyacid-based ionic liquid supported catalyst of the present invention, wherein: the preparation method of the polyacid-based ionic liquid POMs-IL comprises:

Dissolve the vacant polyacid Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O in deionized water to form solution A;

Ionic liquid 1-hexadecyl-3-methylimidazolium chloride salt is dissolved in deionized water to form solution B;

Add solution B dropwise to solution A to form a precipitate, continue to stir for 1 h, filter with suction to obtain the precipitate, and dry at 60-100° C. for 6-24 h to obtain the POMs-IL precursor.

As a preferred solution of the preparation method of the vacant polyacid-based ionic liquid-supported catalyst of the present invention, wherein: the molar ratio of the vacant polyacid to the ionic liquid is 1:9.

As a preferred solution of the preparation method of the deficient polyacid-based ionic liquid-supported catalyst of the present invention, wherein: the preparation method of the deficient polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ includes,

Dissolve POMs-IL in acetonitrile, then add silica, and stir evenly;

Transfer to a hydrothermal reaction kettle, react at 60-100°C for 12-48h, cool down, and then stir and dry at 50°C to obtain a vacant polyacid-based ionic liquid-supported catalyst.

As a preferred scheme of the preparation method of the deficient polyacid-based ionic liquid-supported catalyst in the present invention, wherein: the solid-to-liquid ratio of POMs-IL, silicon dioxide and acetonitrile is 0.5g:1.5g:60mL.

As a preferred solution of the preparation method of the vacant polyacid-based ionic liquid-supported catalyst of the present invention, wherein: the hydrothermal reaction temperature is 80°C, and the reaction time is 24h; the silica is nano-silica, and its particle size is The size is 7-40nm.

Another object of the present invention is to overcome the deficiencies in the prior art, and provide a product prepared by a method for preparing a vacant polyacid-based ionic liquid-supported catalyst.

Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of the product prepared by the preparation method of the vacant polyacid-based ionic liquid-supported catalyst in the oxidative desulfurization of fuel oil.

Beneficial effects of the present invention:

The vacant polyacid-based ionic liquid supported catalyst prepared by the invention has high activity, high stability, can be recycled, and is harmless to the human body and the environment, and is an environmentally friendly material; compared with traditional catalysts, the present invention The prepared catalyst can completely remove difficult-to-remove thiophene sulfides in fuel oil in a short period of time; meanwhile, the preparation method adopted by the invention has mild conditions, no pollution, simple operation and meets environmental protection requirements.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort. in:

Fig. 1 is a schematic diagram of the formation process of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention.

Fig. 2 is an infrared spectrogram of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention.

Fig. 3 is a PXRD pattern of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention.

Figure 4 is the SEM photo of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention, A is the photo of the vacant polyacid Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O, and B is the vacancy Pictures of polyacid-based ionic liquids, panels C and D are pictures of supported catalysts.

Fig. 5 is an effect diagram of the performance investigation of the oxidative desulfurization of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention.

Fig. 6 is an effect diagram of the wide applicability of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention to different sulfides.

Fig. 7 is a cycle performance test chart of the vacant polyacid-based ionic liquid-supported catalyst prepared in the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and comprehensible, the specific implementation manners of the present invention will be described in detail below in conjunction with the embodiments of the specification.

In the following description, a lot of specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described here, and those skilled in the art can do it without departing from the meaning of the present invention. By analogy, the present invention is therefore not limited to the specific examples disclosed below.

Second, "one embodiment" or "an embodiment" referred to herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. "In one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

In the present invention, sodium tungstate, phosphoric acid, and glacial acetic acid all come from Aladdin Pharmaceutical Co., Ltd., 1-hexadecyl-3-methylimidazolium chloride salt comes from Shanghai Yuanye Biotechnology Co., Ltd., and nano-silica comes from Aladdin Pharmaceutical industry, CAS number: 112945-52-5, particle size: 7-40nm, specific surface area (BET): 100m ² /g. Other raw materials are common commercially available products.

Example 1

This embodiment provides a method for preparing a vacant polyacid-based ionic liquid-supported catalyst, and the specific steps are as follows:

(1) Preparation of vacant polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O:

Dissolve 120g of sodium tungstate in 150mL of water, stir until the solid is completely dissolved, then add 4.0mL of 0.06mol (85%) phosphoric acid dropwise to adjust the pH to 9.0;

Add 22.4mL (0.4mol) of glacial acetic acid drop by drop under stirring, resulting in a large amount of white precipitates. The pH of the solution is finally measured to be 7.5±0.3. The solution is stirred for 1 hour, and the precipitate is obtained by suction filtration, and dried to obtain Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O.

(2) Obtain POMs-IL by ion exchange method:

Dissolve 2.564g of vacant polyacid Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O in 100ml of deionized water to form solution A;

Dissolve 3.087g of ionic liquid 1-hexadecyl-3-methylimidazolium chloride salt in 100ml of deionized water to form solution B;

Add solution B dropwise to solution A to form a white precipitate, wherein the molar ratio of the vacant polyacid to the ionic liquid is 1:9;

Stirring was continued for 1 h, the precipitate was filtered out, washed several times until no Cl ^- was detected in the filtrate, the precipitate was obtained by suction filtration, and dried in a blast drying oven at 80°C for 12 h to obtain POMs-IL.

(3) Obtain POMs-IL/SiO ₂ by impregnation method:

Dissolve 0.5g of POMs-IL in 60mL of acetonitrile, then add 1.0g of nano-silica, stir the mixture at 50°C for 30min, then transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor , put it into a blast drying oven and react at 80°C for 24h;

After cooling down, stirring and drying at 50°C, the vacant polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ (1:2) was obtained.

The preparation process of the vacant polyacid-based ionic liquid-supported catalyst material is shown in Figure 1.

Example 2

This embodiment provides a method for preparing a vacant polyacid-based ionic liquid-supported catalyst, and the specific steps are as follows:

(1) Preparation of vacant polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O, which is the same as step (1) in Example 1.

(2) Obtain POMs-IL by ion exchange, which is the same as step (2) in Example 1.

(3) Obtain POMs-IL/SiO ₂ by impregnation method:

Dissolve 0.5g of POMs-IL in 60mL of acetonitrile, then add 1.5g of nano-silica, stir the mixture at 50°C for 30min, then transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor , put it into a blast drying oven and react at 80°C for 24h;

After cooling down, stirring and drying at 50°C, the vacant polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ (1:3) was obtained.

Example 3

This embodiment provides a method for preparing a vacant polyacid-based ionic liquid-supported catalyst, and the specific steps are as follows:

(1) Preparation of vacant polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O, which is the same as step (1) in Example 1.

(2) Obtain POMs-IL by ion exchange, which is the same as step (2) in Example 1.

(3) Obtain POMs-IL/SiO ₂ by impregnation method:

Dissolve 0.5g of POMs-IL in 60mL of acetonitrile, then add 2.0g of nano-silica, stir the mixture at 50°C for 30min, then transfer the mixture to a polytetrafluoroethylene-lined hydrothermal reactor , put it into a blast drying oven and react at 80°C for 24h;

After cooling down, stirring and drying at 50°C, the vacant polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ (1:4) was obtained.

From Figure 2, it can be clearly seen that the infrared characteristic peaks of polyoxometalates, ionic liquids and silica indicate that the supported catalysts were successfully prepared.

It can be clearly seen from Figure 3 that the X-ray diffraction peaks of silica are weaker due to the influence of the amorphous peaks of silica, which belong to polyoxometalates and ionic liquids.

From Figure 4, it can be clearly seen that the morphology change process during the preparation of the catalyst and the morphology characteristics of the catalyst after loading, it can be seen that the vacant polyacid PW ₉ has changed from the original regular crystal shape to a polyacid-based ionic liquid The surface waxy layer structure with good lipophilicity, and finally the small particle supported catalyst with high specific surface area.

Example 4

The oxidative desulfurization performance test of the supported catalyst prepared in Examples 1-3 specifically includes the following steps:

1. Simulated oil configuration

Add 0.290g of dibenzothiophene (DBT) and 0.315g of tetradecane into 100mL of n-octane, and ultrasonicate for 30min to prepare a 500ppm simulated sulfur-containing fuel.

Add 0.216g of benzothiophene (BT) and 0.315g of tetradecane into 100mL of n-octane, and ultrasonicate for 30min to prepare 500ppm simulated sulfur-containing fuel.

Add 0.341g of 4,6-dimethyldibenzothiophene (4.6-DMDBT) and 0.315g of tetradecane into 100mL of n-octane, and ultrasonicate for 30min to prepare a 500ppm simulated sulfur-containing fuel.

2. Fuel oil oxidation desulfurization experiment

A. Take 0.01g of the vacant polyacid-based ionic liquid-supported catalyst _prepared in Examples 1-3 and 32 μL of 30wt% _H2O2 into a 25mL round-bottomed flask containing 5mL of DBT simulated oil and keep stirring , under the condition of 50°C, stir the reaction for 5-30min.

After the reaction, the oily phase was filtered out. Then extract with acetonitrile, separate the upper oil phase, then analyze the sulfur content in the simulated oil by gas chromatography, and calculate the desulfurization rate.

The desulfurization rate calculation formula is:

After several experiments, it was found that, as shown in Figure 5, 0.01 g of vacant polyacid-based ionic liquid-supported catalyst (POMs-IL/SiO2 (1:3)) prepared in Example 2 was mixed with 24 μL of 30 wt% H ₂ O ₂ As an oxidant, the oxidative desulfurization effect is the best at 50°C for 10 minutes, and 100% desulfurization can be achieved.

Then, taking the catalyst POMs-IL/SiO2 (1:3) prepared in Example 2 as an example, its average desulfurization efficiency for BT and 4.6-DMDBT was tested, and the oxidative desulfurization performance diagram was drawn.

B, get respectively the catalyst POMs-IL/SiO ₂ (1:3) and 24 μ L of the catalyst POMs-IL/SiO prepared in embodiment _{2 2} O ₂ Join in the 25 mL round bottom flask that the 4.6-DMDBT simulation oil of 5 mL is housed and and Constantly stirring, under the condition of 50°C, stirring and reacting for 5-30min. After the reaction, the oily phase was filtered out. Then extract with acetonitrile, separate the upper oil phase, then analyze the sulfur content in the simulated oil by gas chromatography, and calculate the desulfurization rate.

C, respectively get the catalyst POMs-IL/SiO ₂ (1:3) and 24 μ L of the catalyst POMs-IL/SiO prepared by 0.01 g embodiment 2 O Join in the 25 mL round bottom flask of the BT simulation oil of 5 mL and keep stirring, at 50 Under the condition of ℃, stir the reaction for 5-30min. After the reaction, the oily phase was filtered out. Then extract with acetonitrile, separate the upper oil phase, then analyze the sulfur content in the simulated oil by gas chromatography, and calculate the desulfurization rate.

Taking the catalyst POMs-IL/SiO ₂ (1:3) prepared in Example 2 as an example, its oxidative desulfurization performance diagram for DBT, BT, and 4.6-DMDBT was drawn. The results are shown in Figure 6. The results show that the vacant polyacid-based ionic liquid-supported catalyst has a good removal effect on thiophene sulfides, and the thiophene sulfides can be basically removed in a relatively short period of time.

Example 5

Cyclic performance test of vacant polyacid-based ionic liquid-supported catalysts.

On the basis of the above-mentioned oxidative desulfurization performance testing experiment, taking the catalyst POMs-IL/SiO ₂ (1:3) prepared in Example 2 as an example, the catalyst was recycled 6 times, and its average desulfurization efficiency for DBT simulated oil was tested, The results are shown in Figure 7, after the vacant polyacid-based ionic liquid-supported catalyst was recycled for 6 times, it still had a high catalytic activity. It can be seen that the prepared vacant polyacid-based ionic liquid-supported catalyst has excellent cycle performance.

The invention combines the vacancy polyoxometalate and the ionic liquid through an ion exchange method to form a polyacid-based ionic liquid, and then loads the ionic liquid on nano silicon dioxide to successfully prepare a supported catalyst. The invention has a simple operation process, the catalyst is a heterogeneous catalyst, is easy to recover, and has better oxidation removal effect on thiophene sulfides in oil products. Especially for dibenzothiophene, when a small amount of hydrogen peroxide (H ₂ O ₂ , 30wt%) is used as the oxidant, efficient and rapid desulfurization can be achieved under mild conditions. The catalyst has the characteristics of high catalytic efficiency, stable structure, good cycle stability and the like.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A preparation method for a lack of polyacid-based ionic liquid supported catalyst, characterized in that: comprising, Preparation of vacant polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O; Using ion exchange to obtain polyacid-based ionic liquid POMs-IL; The vacant polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ was obtained by impregnation method. 2. The preparation method of the vacancy polyacid-based ionic liquid supported catalyst as claimed in claim 1, characterized in that: the vacancy polyoxometalate Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O, Its preparation method includes, Dissolve sodium tungstate in water and stir until the solid is completely dissolved; Then add phosphoric acid dropwise to adjust the pH to 8.9-9.0, add glacial acetic acid drop by drop under stirring to produce a large amount of white precipitate, and finally measure the pH of the solution to be 7.5±0.3, stir the solution for 1 hour, filter with suction to get the precipitate, dry, and finally get Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O. 3. The preparation method of the vacant polyacid-based ionic liquid supported catalyst as claimed in claim 2, characterized in that: the molar ratio of sodium tungstate to phosphoric acid is 6:1. 4. The preparation method of the vacant polyacid-based ionic liquid-supported catalyst according to any one of claims 1 to 3, characterized in that: the preparation method of the polyacid-based ionic liquid POMs-IL comprises: Dissolve the vacant polyacid Na ₉ [A-PW ₉ O ₃₄ ]·7H ₂ O in deionized water to form solution A; Ionic liquid 1-hexadecyl-3-methylimidazolium chloride salt is dissolved in deionized water to form solution B; Add solution B dropwise to solution A to form a precipitate, continue to stir for 1 h, filter with suction to obtain the precipitate, and dry at 60-100° C. for 6-24 h to obtain the POMs-IL precursor. 5. The preparation method of the vacant polyacid-based ionic liquid supported catalyst as claimed in claim 4, characterized in that: the molar ratio of the vacant polyacid to the ionic liquid is 1:9. 6. The preparation method of the vacant polyacid-based ionic liquid-supported catalyst according to any one of claims 1-3, 5, characterized in that: the vacant polyacid-based ionic liquid-supported catalyst POMs-IL/SiO ₂ , its preparation method, comprising, Dissolve POMs-IL in acetonitrile, then add silica, and stir evenly; Transfer to a hydrothermal reaction kettle, react at 60-100°C for 12-48h, cool down, and then stir and dry at 50°C to obtain a vacant polyacid-based ionic liquid-supported catalyst. 7. The preparation method of the vacant polyacid-based ionic liquid supported catalyst as claimed in claim 6, characterized in that: the solid-to-liquid ratio of POMs-IL, silicon dioxide and acetonitrile is 0.5g: 1.5g: 60mL. 8. The preparation method of the vacant polyacid-based ionic liquid supported catalyst as claimed in claim 7, characterized in that: the hydrothermal reaction temperature is 80°C, and the reaction time is 24h; the silica is nano silica, and its particle The diameter is 7-40nm. 9. The vacant polyacid-based ionic liquid-supported catalyst prepared by the preparation method described in any one of claims 1 to 8. 10. The application of the vacant polyacid-based ionic liquid-supported catalyst as claimed in claim 9 in the oxidative desulfurization of fuel oil.

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