Ammonium molybdate ionic liquid for removing organic sulfur in oil product as well as preparation method and application of ammonium molybdate ionic liquid

Abstract

The invention discloses ammonium molybdate ionic liquid for removing organic sulfur in an oil product as well as a preparation method and application of the ammonium molybdate ionic liquid. The compound ionic liquid desulfurizing agent comprises ammonium molybdate ionic liquid, an oxidizing agent and an extracting agent, the ionic liquid is 1-alkyl imidazole ammonium molybdate, wherein alkyl is saturated straight-chain alkane. The preparation method of the ammonium molybdate ionic liquid is wide in universality, excellent in performance and high in stability, can be used for removing organic sulfides such as thiophene, benzothiophene and dibenzothiophene in oil products, is suitable for purification treatment of liquid oil products such as petroleum, gasoline and lubricating oil containing organic sulfur, has high reaction activity, and can be used for preparing the liquid oil products. According to the present invention, the catalyst has characteristics of high desulfurization efficiency at the normal temperature, strong thermal stability and strong cycle performance, has the removal efficiency of 82.47% after the continuous catalysis cycle for 5 times, and can meet the requirement of the continuous stable operation to remove the thiophene sulfide in the oil product.

Description

Technical Field

[0001] The invention relates to the technical field of ionic liquid and organic molybdenum, and in particular to a preparation method of ammonium molybdate ionic liquid and application thereof in catalytic oxidation desulfurization. Background Art

[0002] Room temperature ionic liquids are molten salt systems composed of specific cations and anions that are liquid at room temperature or near room temperature. They have the advantages of extremely low vapor pressure, low melting point, high heat capacity and high stability. They have good solubility in inorganic compounds, organic compounds, metal organic compounds, etc. Their polarity and wettability can be adjusted by the length of the alkyl carbon chain and different anions, so they are also called "designable solvents". Since ionic liquids do not cause solvent loss and environmental pollution due to unit operations such as distillation when used for separation, ionic liquids are suitable for use in extraction processes. By coupling the reaction process with the extraction process through oxidation, a reactive extraction desulfurization method is designed to improve the single desulfurization efficiency. The principle is to oxidize sulfides into more polar sulfones through chemical reactions, break the distribution ratio of sulfides in the two phases, increase their distribution constant in the ionic liquid phase, and thus improve the ionic liquid extraction desulfurization efficiency. In practical applications, ionic liquid catalysts also face the problem of repeated use. Therefore, the study of ionic liquid catalysts with high catalytic performance and recyclability at room temperature is of great significance to the field of industrial desulfurization. Summary of the invention

[0003] The purpose of the present invention is to provide an ammonium molybdate ionic liquid for removing organic sulfur from oil products, a composite ionic liquid desulfurizer containing the ammonium molybdate ionic liquid, and applications thereof. The composite ionic liquid desulfurizer of the present invention has high catalytic performance and circulation performance.

[0004] To achieve the above object, the technical solution adopted by the present invention is: an ammonium molybdate ionic liquid for removing organic sulfur from oil products, wherein the ammonium molybdate ionic liquid is 1-alkyl imidazole ammonium molybdate salt, having the general structural formula shown in (I):

[0005]

[0006] Wherein, R is a saturated straight-chain alkane.

[0007] Preferably, R is methyl, ethyl, butyl or octyl.

[0008] A method for preparing ammonium molybdate ionic liquid for removing organic sulfur from oil products comprises the following steps:

[0009] 1) Using acetonitrile as solvent, methyl bromoacetate was slowly added dropwise to N-alkylimidazole, and the mixture was stirred continuously until the addition was complete. The mixture was heated to 80° C., refluxed for 8 h, cooled to room temperature, washed with n-hexane, rotary evaporated, and dried in vacuo to obtain intermediate 1.

[0010] 2) The intermediate 1 and diethanolamine were reacted at 70° C. for 14 h, cooled to room temperature, extracted with n-hexane, rotary evaporated, and vacuum dried to obtain the intermediate 2.

[0011] 3) Under nitrogen protection, molybdenum trioxide was slowly added to intermediate 2 with stirring, and an equal volume of toluene was added as a water-carrying agent. The temperature was raised to 120° C. and refluxed for 3 to 4 hours. After the reaction was completed, the mixture was filtered, distilled under reduced pressure, and dried in vacuum to obtain intermediate 3;

[0012] 4) Using acetone as solvent, the intermediate 3 and ammonium heptamolybdate were mixed, and the mixture was stirred at room temperature for 48 h. After the reaction was completed, the mixture was vacuum filtered, washed with n-hexane, rotary evaporated, and vacuum dried to obtain the target product.

[0013] Preferably, in molar ratio, intermediate 3:ammonium heptamolybdate=3:1.

[0014] The invention discloses an application of the ammonium molybdate ionic liquid as a catalyst in removing organic sulfur from oil products.

[0015] A composite ionic liquid desulfurizer for removing organic sulfur from oil products. The composite ionic liquid adopts the above-mentioned ammonium molybdate ionic liquid for removing organic sulfur from oil products, and comprises, by mass percentage, 0.25-1.25% of ammonium molybdate ionic liquid, 0.9-2.21% of oxidant, and the remainder of extractant.

[0016] Preferably, the oxidant is selected from C 4 HO 2 , H 2 O 2 、KMnO 4 and K 2 Cr 2 O 7 One of them.

[0017] More preferably, the oxidant is H 2 O 2 .

[0018] Preferably, the extractant is selected from one of acetonitrile, pyrrolidone, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), alcohols, and low eutectic solvents (DESs).

[0019] More preferably, the extractant is acetonitrile.

[0020] The invention discloses an application of the composite ionic liquid desulfurizing agent in removing organic sulfur from oil products.

[0021] Preferably, the method is as follows: add a composite ionic liquid desulfurizer to an oil product containing organic sulfur, and react at 30-70° C. with vigorous stirring for 2 hours.

[0022] In the present invention, preferably, the molar ratio of the oxidant to the sulfide in the oil product is O / S=6-10, preferably O / S=6.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The composite ionic liquid desulfurizer provided by the present invention has simple ingredients. The ionic liquid contains anions with catalytic oxidation desulfurization ability and has the characteristics of non-volatility, good thermal stability, and recyclability. The oxidant and the extractant are insoluble in the oil product, and the oil product is easy to separate.

[0025] 2. The composite ionic liquid desulfurizer provided by the present invention has high reaction activity, high desulfurization efficiency at room temperature, and strong cycle performance. After 5 consecutive cycles, the desulfurization rate is still as high as 82.47%, which can meet the continuous and stable operation of the desulfurization process.

[0026] 3. The composite ionic liquid desulfurizer provided by the present invention does not add any other chemical components that are hazardous wastes, and will not cause new environmental problems during the desulfurization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the 1-ethylimidazole diethanolamide molybdate ionic liquid synthesized in Example 1.

[0028] Figure 2 This is the Fourier infrared spectrum of the 1-ethylimidazole diethanolamide molybdate ionic liquid synthesized in Example 1.

[0029] Figure 3 This is a graph showing the effect of different ionic liquid catalysts on the desulfurization rate in Example 5.

[0030] Figure 4 This is a graph showing the effect of the amount of ionic liquid catalyst used on the desulfurization rate in Example 5.

[0031] Figure 5 This is a graph showing the effect of the amount of oxidant used on the desulfurization rate in Example 5.

[0032] Figure 6 This is a graph showing the effect of reaction temperature on desulfurization rate in Example 5.

[0033] Figure 7 This is a comparison chart of the desulfurization effects of different thiophene sulfur-containing compounds in Example 5.

[0034] Figure 8 This is the cycle performance diagram of the catalyst in Example 5.

[0035] Fig. 9This is the infrared spectrum analysis characterization diagram of benzothiophene oxide in Example 5. DETAILED DESCRIPTION

[0036] Example 1 1-ethyl imidazolyl ammonium molybdate ionic liquid (I) has the following structural formula:

[0037]

[0038] (II) The preparation method is as follows:

[0039] 1. Preparation of 1-ethyl-3-methylacetate imidazolium bromide ionic liquid:

[0040] Take N-ethylimidazole (9.613 g, 0.1 mol) and methyl bromoacetate (18.357 g, 0.12 mol), use 50 mL of acetonitrile as solvent, use a constant pressure funnel to slowly add methyl bromoacetate to N-ethylimidazole, stir continuously until the addition is complete, heat to 80 ° C, reflux reaction for 8 hours, the reaction is completed, wait for the liquid initial product to cool to room temperature, add an equal volume of n-hexane for washing, and remove the solvent and excess methyl bromoacetate by rotary evaporation. Repeat the washing and rotary evaporation steps 3 times, put the resulting product into a vacuum drying oven, and dry it at 80 ° C for 48 hours to obtain a brown-yellow viscous liquid, which is 1-ethyl-3-methylacetate imidazolium bromide ionic liquid for standby use.

[0041] 2. Preparation of 1-ethylimidazole diethanolamide ionic liquid

[0042] Take 1-ethyl-3-acetic acid methyl imidazolium bromide ionic liquid (24.91 g, 0.1 mol) and diethanolamine (26.285 g, 0.25 mol), react at 70°C for 14 h, cool to room temperature, add an equal volume of n-hexane and extract repeatedly 3 to 6 times, remove the solvent by rotary evaporation, put the resulting product into a vacuum drying oven, and vacuum dry it at 70°C for 48 h to obtain 1-ethylimidazole diethanolamide ionic liquid for standby use.

[0043] 3. Preparation of 1-ethylimidazole diethanolamide molybdate ionic liquid

[0044] Take 1-ethylimidazole diethanolamide ionic liquid (33.79 g, 0.1 mol) and molybdenum trioxide (17.275 g, 0.12 mol), under nitrogen protection, slowly add molybdenum trioxide to 1-ethylimidazole diethanolamide ionic liquid with stirring, add an equal volume of toluene as a water-carrying agent, heat to 120 ° C and reflux for 3.5 hours. After the reaction is completed, filter out the unreacted molybdenum trioxide, and remove the water-carrying agent toluene by vacuum distillation. The resulting product is placed in a vacuum drying oven and vacuum dried at 55 ° C for 48 hours to obtain an oily dark green transparent liquid, which is 1-ethylimidazole diethanolamide molybdate ionic liquid.

[0045] 4. 1-Ethyl imidazolyl ammonium molybdate ionic liquid

[0046] In a molar ratio of 3:1, ammonium heptamolybdate (19.601 g, 0.33 mol) was taken, and acetone was used as a solvent. The obtained 1-ethylimidazole diethanolamide molybdate ionic liquid (44.79 g, 0.1 mol) was mixed with ammonium heptamolybdate, and the reaction was stirred at room temperature for 48 hours. After the reaction was completed, vacuum filtration was performed to remove unreacted ammonium heptamolybdate, and the obtained transparent solution was further washed with an equal volume of n-hexane, and the solvent was removed by rotary evaporation. The obtained product was placed in a vacuum drying oven and vacuum dried at 70°C for 120 hours to obtain 1-ethylimidazole ammonium molybdate ionic liquid.

[0047] (III) Characterization

[0048] Figure 1 This is the H NMR spectrum of 1-ethylimidazole diethanolamide molybdate ionic liquid 1 H-NMR (D 2 O, 300MHz, 298K). Figure 1 The synthesis of 1-ethylimidazole diethanolamide molybdate ionic liquid was confirmed.

[0049] Figure 2 This is the Fourier transform infrared spectrum (FT-IR) of 1-ethylimidazole diethanolamide molybdate ionic liquid. Figure 2 The synthesis of 1-ethylimidazole diethanolamide molybdate ionic liquid was confirmed.

[0050] Example 2 1-Methylimidazolium ammonium molybdate ionic liquid (I) has the following structural formula:

[0051]

[0052] (II) The preparation method is as follows:

[0053] The preparation method is the same as that of Example 1, except that 0.1 mol of N-ethylimidazole is replaced by 0.1 mol of N-methylimidazole.

[0054] Example 3 1-Butyl imidazole ammonium molybdate ionic liquid (I) has the following structural formula:

[0055]

[0056] (II) The preparation method is as follows:

[0057] The preparation method is the same as that of Example 1, except that 0.1 mol of N-ethylimidazole is replaced by 0.1 mol of N-butylimidazole.

[0058] Example 4 1-octylimidazole ammonium molybdate ionic liquid (I) has the following structural formula:

[0059]

[0060] (II) The preparation method is as follows:

[0061] The preparation method is the same as that of Example 1, except that 0.1 mol of N-ethylimidazole is replaced by 0.1 mol of N-octylimidazole.

[0062] Example 5 A composite ionic liquid desulfurizer and a method for removing organic sulfur from oil products

[0063] Preparation of model oil (oil-T): Accurately weigh 0.3287 g of thiophene and dissolve it in n-octane. Use a 250 mL volumetric flask to make a thiophene model oil with a sulfur content of 500 mg / L for the following experiments.

[0064] Preparation of model oil (oil-BT): Accurately weigh 0.5242 g of benzothiophene and dissolve it in n-octane. Use a 250 mL volumetric flask to make a benzothiophene model oil with a sulfur content of 500 mg / L for the following experiments.

[0065] Preparation of model oil (oil-DBT): Accurately weigh 0.722 g of dibenzothiophene and dissolve it in n-octane. Use a 250 mL volumetric flask to make a dibenzothiophene model oil with a sulfur content of 500 mg / L for the following experiments.

[0066] (I) Effect of different alkyl-substituted ammonium molybdate ionic liquids on desulfurization rate

[0067] Preparation of composite ionic liquid desulfurizer and method for removing organic sulfur from oil products: add ammonium molybdate ionic liquid (100 mg) prepared in Example 1-4 and 30% hydrogen peroxide (240 μL, 266.4 mg) to the reaction container respectively, stir at room temperature for pretreatment for 10 min, then add acetonitrile (25 mL, 19500 mg) as an extractant, stir evenly, and obtain composite ionic liquid desulfurizer containing ammonium molybdate ionic liquids with different alkyl substitutions, with a mass percentage of 0.503% ammonium molybdate ionic liquid and a mass percentage of 1.341% hydrogen peroxide. Add 25 mL of model oil (oil-BT) to the composite ionic liquid desulfurizer obtained above, react at 60°C with vigorous stirring for 2 h, take the upper organic phase for sampling and analysis at intervals, and calculate the desulfurization rate.

[0068] Depend on Figure 3The results show that as the carbon chain of the cationic organic functional group in the ammonium molybdate ionic liquid increases, the catalytic effect first becomes better, and then basically tends to be consistent. The reason is that as the carbon chain of the cation of the catalyst ammonium molybdate ionic liquid increases, the emulsification effect of the catalyst and the model oil becomes stronger and stronger, and the catalysis is regarded as a homogeneous system to a certain extent. Therefore, the probability of the catalyst contacting the oxidized benzothiophene (BT) is greater than that of the catalyst with a short carbon chain. The ammonium molybdate ionic liquid with an octyl substituent has the best catalytic efficiency, and the desulfurization rate can reach 84.12%.

[0069] (II) Effect of the dosage of ammonium molybdate ionic liquid on the desulfurization rate

[0070] Preparation of composite ionic liquid desulfurizer and method for removing organic sulfur from oil products: 1-octylimidazole ammonium molybdate ionic liquid (49.54 mg, 99.33 mg, 149.37 mg, 199.66 mg, 250.21 mg) prepared in Example 4 and 30% hydrogen peroxide (240 μL, 266.4 mg) were added to the reaction container respectively, stirred at room temperature for 10 min, then acetonitrile (25 mL, 19500 mg) was added as an extractant, stirred evenly, and composite ionic liquid desulfurizers with a mass percentage of 1-octylimidazole ammonium molybdate ionic liquid of 0.25%, 0.5%, 0.75%, 1%, and 1.25% were obtained respectively. 25 mL of model oil (oil-BT) was added to the composite ionic liquid desulfurizer obtained above, and the reaction was carried out at 60°C under vigorous stirring for 2 h. The upper organic phase was sampled and analyzed at intervals to calculate the desulfurization rate.

[0071] Depend on Figure 4 The results show that when the mass percentage of the catalyst 1-octylimidazole ammonium molybdate ionic liquid is 0.25%, the desulfurization rate can only reach 81.55%, and the sulfur content in the system is still 92.25 mg / L, and the desulfurization rate is low. As the amount of catalyst increases, the desulfurization effect gradually increases. When the catalyst dosage is 0.75wt%, the desulfurization rate reaches 84.02% after 30 minutes of reaction, and the sulfur content in the system is 79.9 mg / L. When the reaction is 60 minutes, the desulfurization rate reaches 86.75%, and the sulfur content in the system is only 66.25 mg / L, achieving a good desulfurization effect. Continue to increase the amount of catalyst, the reaction time required for desulfurization is reduced, but considering the comprehensive reaction cost, the mass percentage of the preferred catalyst ammonium molybdate ionic liquid of the present invention is 0.75wt%.

[0072] (III) Effect of oxidant dosage on desulfurization rate

[0073] Preparation of composite ionic liquid desulfurizer and method for removing organic sulfur from oil products: 1-octylimidazole ammonium molybdate ionic liquid (149.37 mg) prepared in Example 4 and 30% hydrogen peroxide (80 μL, 160 μL, 240 μL, 320 μL, 400 μL) were added to the reaction container respectively, and the mixture was pretreated at room temperature for 10 min, and then acetonitrile (25 mL, 19500 mg) was added as an extractant, and stirred evenly to obtain composite ionic liquid desulfurizers with a hydrogen peroxide mass percentage of 0.45%, 0.90%, 1.34%, 1.78%, and 2.21%, respectively. 25 mL of model oil (oil-BT) was added to the composite ionic liquid desulfurizer obtained above, and the mixture was reacted at 60°C under vigorous stirring for 2 h. The upper organic phase was sampled and analyzed at intervals to calculate the desulfurization rate.

[0074] In oxidative extraction desulfurization, the amount of oxidant is an important part of the whole reaction, so studying the oxygen-sulfur ratio (O / S) is an essential task. Figure 5 It can be seen that when the amount of hydrogen peroxide is 80 μL, that is, O / S=2, the desulfurization rate can only reach 79.0%. The possible reasons for this phenomenon are as follows: due to the dispersion of hydrogen peroxide, the concentration of completely oxidized benzothiophene (BT) cannot be reached. As the oxygen-sulfur ratio (O / S) increases, the desulfurization rate increases significantly. When the amount of hydrogen peroxide is 240 μL, that is, O / S=6, the desulfurization rate reaches 86.75% in a reaction time of 60 min, and the sulfur content in the system is 66.25 mg / L, achieving a good desulfurization effect. Continuing to increase the amount of hydrogen peroxide will not have much benefit for the desulfurization of the system, but will cause a waste of hydrogen peroxide. Therefore, the mass percentage of hydrogen peroxide preferred in the present invention is 1.34%.

[0075] (IV) Effect of reaction temperature on desulfurization rate

[0076] Preparation of composite ionic liquid desulfurizer and method for removing organic sulfur from oil products: add 1-octylimidazole ammonium molybdate ionic liquid (149.37 mg) prepared in Example 4 and 30% hydrogen peroxide (240 μL, 266.4 mg) to the reaction container respectively, stir at room temperature for pretreatment for 10 min, then add acetonitrile (25 mL, 19500 mg) as an extractant, stir evenly, and obtain composite ionic liquid desulfurizers with a mass percentage of 0.75% of 1-octylimidazole ammonium molybdate ionic liquid and a mass percentage of 1.34% of hydrogen peroxide. Add 25 mL of model oil (oil-BT) to the composite ionic liquid desulfurizer obtained above, react for 2 h at 30°C, 40°C, 50°C, 60°C, and 70°C under vigorous stirring, take the upper organic phase for sampling and analysis at intervals, and calculate the desulfurization rate.

[0077] Depend on Figure 6It can be seen that as the temperature increases, the desulfurization rate also increases continuously. At 30°C, the desulfurization effect is poor and basically fails to meet the desulfurization requirements. When the reaction temperature is 60°C, it only takes 60 minutes to make the desulfurization rate reach a maximum of 86.92%. When the reaction temperature is 70°C, the catalytic oxidation rate is the highest before 30 minutes, but the desulfurization rate decreases after 60 minutes, which may be caused by the partial decomposition of hydrogen peroxide. Therefore, the preferred desulfurization temperature of the present invention is 60°C and the desulfurization time is 60 minutes.

[0078] (V) Comparison of desulfurization effects of different thiophene sulfur-containing compounds

[0079] Preparation of composite ionic liquid desulfurizer and method for removing organic sulfur from oil products: 1-octylimidazole ammonium molybdate ionic liquid (149.37 mg) prepared in Example 4 and 30% hydrogen peroxide (240 μL, 266.4 mg) were added to the reaction container respectively, stirred at room temperature for pretreatment for 10 min, then acetonitrile (25 mL, 19500 mg) was added as an extractant, stirred evenly, and composite ionic liquid desulfurizers with a mass percentage of 0.75% of 1-octylimidazole ammonium molybdate ionic liquid and a mass percentage of 1.34% of hydrogen peroxide were obtained. 25 mL of model oil (oil-T), model oil (oil-BT) and model oil (oil-DBT) were added to the composite ionic liquid desulfurizer obtained above, and the reaction was carried out at 60°C under vigorous stirring for 60 min. The upper organic phase was sampled and analyzed at intervals to calculate the desulfurization rate.

[0080] from Figure 7 It can be seen that under the same experimental conditions, the desulfurization rate of DBT can reach 94.77% when the reaction time is 1h, and the desulfurization rate of BT can also reach 86.92%, but T is only 43.59%. It shows that the existence form of sulfide in the simulated oil has a great influence on the removal effect, and the desulfurization rate of sulfide is in the order of DBT>BT>T. The reactivity of polycyclic sulfide increases with the increase of the π electron cloud density on the ring. The electron cloud density on dibenzothiophene is 5.758, the electron cloud density on benzothiophene is 5.739, and the electron cloud density on thiophene is the lowest at 5.696, resulting in the worst desulfurization effect.

[0081] (VI) Catalyst Cycling Performance

[0082] Under the optimal reaction conditions, the BT simulated oil was catalyzed for oxidative desulfurization. After the reaction was completed, the simulated oil phase was removed by pouring, and fresh simulated oil and hydrogen peroxide were added to the remaining ionic liquid phase for the next reaction. The cycle was repeated five times. As the number of cycles increased, the desulfurization rate decreased slightly to 82.47%, and white solid was observed. The results are as follows: Figure 8As shown, the generated white crystals were characterized by infrared spectroscopy. Fig. 9 shown.

[0083] like Fig. 9 By comparing with the infrared spectrum of benzothiophene, we can see that at 1288cm -1 and 1191cm -1 -SO 2 The characteristic absorption peak of benzothiophene sulfone (BTO) was obtained. 2 ).Depend on Figure 8 It can be seen that the desulfurization rate gradually decreases with the increase of the number of cycles. After the fifth cycle, the desulfurization rate becomes 82.47%. The reason for the above situation is that acetonitrile has good solubility for the product as an extractant, but any solvent has its saturated solubility for the solute, that is, in this system, the ionic liquid is basically saturated, and its solubility for the oxidation product decreases, so the sulfur content in the organic phase becomes higher. At the same time, with the increase of the number of cycles, the amount of hydrogen peroxide added is increasing, resulting in more and more water in the system, and the emulsification degree of the system is increasing. After emulsification, the mass transfer capacity in a small range decreases, which will cause incomplete oxidation, thereby causing a decrease in the desulfurization rate.

[0084] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. An ammonium molybdate ionic liquid for removing organic sulfur from oil products, characterized in that: The ammonium molybdate ionic liquid has the general structural formula shown in (I): Wherein, R is a saturated straight-chain alkane.

2. The ammonium molybdate ionic liquid for removing organic sulfur from oil products according to claim 1, characterized in that: The R is methyl, ethyl, butyl or octyl.

3. The method for preparing an ammonium molybdate ionic liquid for removing organic sulfur from oil products according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: 1) Using acetonitrile as solvent, slowly drop methyl bromoacetate into N-alkyl imidazole, stir until the dropwise addition is complete, heat to 80°C, reflux for 8h, cool to room temperature, wash with n-hexane, rotary evaporate, and vacuum dry to obtain intermediate 1; 2) React the intermediate 1 and diethanolamine at 70°C for 14 h, cool to room temperature, extract with n-hexane, and evaporate by rotary evaporation. Vacuum drying to obtain intermediate 2; 3) Under nitrogen protection, molybdenum trioxide was slowly added to intermediate 2 with stirring, and an equal volume of toluene was added as a water-carrying agent. The temperature was raised to 120° C. and refluxed for 3 to 4 hours. After the reaction was completed, the mixture was filtered, distilled under reduced pressure, and dried in vacuum to obtain intermediate 3; 4) Using acetone as solvent, the intermediate 3 and ammonium heptamolybdate were mixed, and the mixture was stirred at room temperature for 48 h. After the reaction was completed, the mixture was vacuum filtered, washed with n-hexane, rotary evaporated, and vacuum dried to obtain the target product.

4. The preparation method according to claim 3, characterized in that: In molar ratio, intermediate 3:ammonium heptamolybdate=3:

1.

5. Use of the ammonium molybdate ionic liquid according to claim 1 or 2 as a catalyst in removing organic sulfur from oil products.

6. A composite ionic liquid desulfurizer for removing organic sulfur from oil products, characterized in that: The composite ionic liquid desulfurizer adopts the ammonium molybdate ionic liquid for removing organic sulfur from oil products as claimed in claim 1 or 2, and comprises, by mass percentage, 0.25-1.25% of ammonium molybdate ionic liquid, 0.9-2.21% of oxidant, and the remainder of extractant.

7. The composite ionic liquid desulfurizer for removing organic sulfur from oil products according to claim 6, characterized in that: The oxidant is selected from one of C4HO2, H2O2, KMnO4 and K2Cr2O7.

8. The composite ionic liquid desulfurizer for removing organic sulfur from oil products according to claim 6, characterized in that: The extractant is selected from one of acetonitrile, pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, alcohols and low eutectic flux.

9. Use of the composite ionic liquid desulfurizer according to claim 6, 7 or 8 in removing organic sulfur from oil products.

10. The use according to claim 8, characterized in that: The method is as follows: add a composite ionic liquid desulfurizer to an oil product containing organic sulfur, and react at 30-70°C with vigorous stirring for 2 hours.

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