Confined Anderson polymetallic oxygen cluster solid phase compound and its application in deep desulfurization of diesel fuel

Abstract

The present invention discloses a confined Anderson polymetallic oxygen cluster solid phase compound and its application in deep desulfurization of diesel. The present invention uses 1,8-diazabicycloundecane-7-ene and N,N'-carbonyldiimidazole for modification, and after the introduction of imidazole, bromide ions are introduced by treating with n-butyl bromide, and then the polymetallic oxygen cluster is confined by an ion exchange method to obtain a confined Anderson polymetallic oxygen cluster solid phase compound. The solid phase compound of the present invention achieves the effect of heterogeneity of homogeneous catalysts. The solid phase compound of the present invention is used as a catalyst for deep desulfurization reaction of diesel. The preparation method of the present invention overcomes the shortcomings of polymetallic oxygen clusters that are easy to dissolve and difficult to recover, and shows high stability and high reusability, and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of heterogeneous catalysis and relates to a confined Anderson polymetallic oxygen cluster solid phase compound and its application in deep desulfurization of diesel. Background Art

[0002] In recent years, although renewable energy sources have been continuously developed, traditional fuels still dominate. After diesel is burned by motor vehicles, the sulfur in it is oxidized to form SOx, which can not only corrode the engine and reduce the engine's service life, but also cause acid rain and cause environmental pollution problems. Therefore, countries around the world have strictly regulated the sulfur content in diesel. Hydrodesulfurization technology (HDS) is the most widely used technology in industrial applications. It can effectively remove aliphatic organic sulfides. However, due to the influence of steric hindrance, the removal effect of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and its derivatives is poor, and the conditions are harsh, requiring high temperature and high pressure. Oxidative desulfurization (ODS) is a supplement or alternative to HDS deep desulfurization. It has attracted much attention due to its mild reaction conditions, high efficiency and low energy consumption. Using oxygen as an oxidant is environmentally friendly, but it is not easy to be activated under mild conditions. High temperature or the addition of sacrificial agents is required to obtain high oxidation performance. Anderson-type polymetallic oxygen clusters have high solubility in water and organic solutions, which makes catalyst recovery difficult. Previous work has found that Anderson-type polyoxometalates exhibit excellent desulfurization performance under mild conditions without the addition of sacrificial agents. This POM has a special planar structure in which the octahedral oxide of the central metal is surrounded by six edge-shared MO 6 (M=W or Mo) octahedron surrounded, each metal skeleton atom (W or Mo) has two terminal oxygen atoms, and has high catalytic activity. However, most Anderson-type polymetallic oxygen clusters are easily soluble in water and organic solutions, especially in the oxidative desulfurization system of heteropolyacids and low eutectic solvents. The heteropolyacid catalyst dissolves in the low eutectic solvent, which makes it difficult to recover and reuse the heteropolyacid catalyst. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a confined Anderson polymetallic oxygen cluster solid phase compound and its application in deep desulfurization of diesel.

[0004] To achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0005] A solid phase compound of a confined Anderson polyoxometallic cluster, wherein the preparation of the solid phase compound comprises the following steps:

[0006] 1) Add 2-aminoterephthalic acid, chromium nitrate and sodium hydroxide in excess deionized water in a mass ratio of 1-3:2-6:1 and stir until uniformly dispersed.o After hydrothermal reaction at C for 18-24 h, the intermediate I is obtained after filtration, washing and drying;

[0007] 2) The intermediate I and 1,8-diazabicycloundec-7-ene prepared in step 1) are added to excess toluene and dispersed evenly, and then N,N'-carbonyldiimidazole is added, stirred until the reaction is complete, and then filtered, washed, and dried to obtain intermediate II.

[0008] Wherein, the mass ratio of the intermediate I, 1,8-diazabicycloundec-7-ene and N,N'-carbonyldiimidazole prepared in step 1) is 1000:1-5:300-400;

[0009] 3) Disperse the intermediate II prepared in step 2) in toluene, slowly add n-butyl bromide at 0 °C, stir evenly, and heat at 70 o C and reflux until the reaction is complete, then filter, wash and dry to obtain intermediate III.

[0010] Wherein, the mass ratio of the intermediate II prepared in step 2) to n-butyl bromide is 1:0.1-0.5;

[0011] 4) After dissolving the Anderson polyoxometalate in acetonitrile, add the intermediate III prepared in step 3) and stir for 72 h until the reaction is complete. After filtering, washing and drying, the product is obtained.

[0012] Among them, Anderson polyoxometallic clusters are (NH 4 ) 3 Co(OH) 6 Mo 6 O 18 、Na 3 Fe(OH) 6 Mo 6 O 18 、Na 3 Cr(OH) 6 Mo 6 O 18 Any one of the above, the molar ratio of Anderson polyoxometalate to the intermediate III prepared in step 3) is 0.1-4:1.

[0013] Preferably, the Anderson polyoxometalate in step 4) is (NH 4 ) 3 Co(OH) 6 Mo 6 O 18 (CoMo 6 )、Na 3 Fe(OH) 6 Mo 6O 18 (FeMo 6 )、Na 3 Cr(OH) 6 Mo 6 O 18 (CrMo 6 )

[0014] Application of solid phase compounds of confined Anderson polyoxometallic clusters as catalysts for deep desulfurization of diesel.

[0015] The data in the specific examples effectively verify that the solid phase compound of the confined Anderson polyoxometallic cluster of the present invention can be used as a catalyst in an oxidative desulfurization system containing a low eutectic solvent, and can be used as a deep desulfurization catalyst for treating low-sulfur diesel.

[0016] Beneficial effects of the present invention

[0017] The solid phase compound of the confined Anderson polyoxometallic cluster of the present invention is applied in the oxidative desulfurization reaction with oxygen as an oxidant.

[0018] The solid phase compound of the confined Anderson polyoxometallic cluster prepared by the present invention is not miscible with the low eutectic solvent and the oil product, and the oil product can be well separated after the reaction is completed. In addition, the solid phase compound of the confined Anderson polyoxometallic cluster and the low eutectic solvent are incompatible with each other, and the catalyst can be effectively separated by adding acetonitrile. After the catalyst activity is reduced, the catalytic activity can be restored by simply washing with acetonitrile.

[0019] Moreover, since the solid phase compound of the confined Anderson polyoxometallic clusters not only confines the polyoxometallic clusters to the pores, but also the polyoxometallic clusters exchange ions with the bromide ions therein, generating electrostatic interactions, the stability of the solid phase compound of the confined Anderson polyoxometallic clusters is improved. Therefore, the solid phase compound of the confined Anderson polyoxometallic clusters of the present invention has excellent stability, and the catalytic activity remains unchanged even if the catalyst is washed with hot water.

[0020] The innovation of the present invention lies in the preparation of a solid-phase compound loaded with polyoxometallic clusters, which realizes the confinement and immobilization of soluble polyoxometallic clusters, not only overcoming the shortcomings of polyoxometallic clusters such as high solubility, low surface area, and difficulty in recovery, but also retaining the high catalytic activity of polyoxometallic clusters for oxidative desulfurization reactions, especially for the deep desulfurization of low-sulfur oil products. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 As catalyst (limited CoMo 6 Infrared spectrum during the synthesis of solid phase compounds.

[0022] FIG. 2 shows the recovery and utilization data of the catalyst in Example 1.

[0023] Figure 3 GC-FPD spectra of sulfides in the real oil product (commercial diesel I) of Example 1 before and after oxidative desulfurization. Implementation

[0024] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0025] Example 1: Limited Domain CoMo 6 Preparation of solid phase compound (1 / 10)

[0026] Preparation of intermediate I: 180 mg of 2-aminoterephthalic acid, 400 mg of chromium nitrate and 100 mg of sodium hydroxide were added to 7.5 mL of deionized water and stirred for 1 h. o C for 24 h, and the green solid product was collected by filtration. In order to remove the unreacted 2-ATPA, the crude product was heated to 40 °C with DMF at 60 °C. o C for 1 h, and then washed with ethanol at 70 o C for 3 h, 100 o C and dried under vacuum for 24 h to obtain intermediate I.

[0027] Preparation of intermediate II: 1 g of intermediate I and 3 mg of 1,8-diazabicycloundec-7-ene were added to 20 mL of toluene. After stirring at room temperature for 1 h, 357 mg of N,N'-carbonyldiimidazole was added and stirred at room temperature for 12 h. The solution was filtered, and the solid was washed three times with 100 mL of toluene and dried under vacuum at 100 °C for 12 h to obtain intermediate II.

[0028] Preparation of intermediate III: 1.2 g of intermediate II was added with 20 mL of toluene. 360 mg of n-butyl bromide was slowly added to the mixture at 0 °C and stirred for 1 h. o C for 24 h. The solution was filtered, and the solid was washed several times with 100 mL of toluene and then heated at 100 o C was dried in a vacuum oven for 12 h to obtain intermediate III.

[0029] Preparation of CoMo 6 Intermediate III (1 / 10): 0.01 mmol (NH 4 ) 3 Co(OH) 6 Mo 6 O 18Dissolved in 5 mL acetonitrile, then added 0.1 mmol of intermediate III, stirred for 72 h, washed with acetonitrile and filtered, 60 o C overnight drying to obtain the catalyst confined CoMo 6 Solid phase compound (1 / 10).

[0030] The infrared test results are as follows: Figure 1 As shown in the infrared image of the confined Anderson polyoxometallic cluster solid phase compound, in addition to the characteristic peaks of intermediate III, there are also (NH 4 ) 3 H 6 CoMo 6 O 24 The characteristic peaks of 580 and 655 cm -1 The characteristic peaks near the bridge bond Mo-O-Mo, 896 and 945 cm -1 The characteristic peaks near the end group belong to the vibration of Mo=O. This proves that the confined CoMo 6 Solid phase compounds.

[0031] 1. Application of oxidative desulfurization in model diesel (deep eutectic solvent and confined CoMo 6 Solid phase compound system)

[0032] Prepare the low eutectic solvent: mix p-toluenesulfonic acid and polyethylene glycol 4000 in a ratio of 1:2 (molar ratio) and heat to 80 o C, vigorously stir, and react for 1 h to obtain a deep eutectic solvent.

[0033] Desulfurization of diesel fuel: 4 g of deep eutectic solvent and 20 mL of model diesel fuel (dibenzothiophene dissolved in decahydronaphthalene, S: 500 ppm) were added to a 100 mL three-necked round-bottom flask, respectively, and placed in an oil bath at a temperature of 90 °C. o C, stirred and extracted for 30 min, and the catalyst CoMo was added to confine the 6 20 mg of solid phase compound (1 / 10) was placed in a round-bottom flask, oxygen flow rate was 60 mL / min, stirring and timing to start the reaction, stirring was stopped after 2 hours, and after standing and stratification, 0.5 mL of the upper diesel phase was sampled in a sample bottle. The sulfur content was determined by GC-FPD. The desulfurization rate reached 100%.

[0034] 2. Separation of deep eutectic solvent and catalyst

[0035] After the reaction is completed, the mixture is allowed to stand at room temperature, the upper clear oil phase is separated, and the lower eutectic solvent is mixed with the confined CoMo 6The mixture of solid phase compounds is transferred to a centrifuge tube, acetonitrile is added for centrifugation, washing, and separation by suction filtration to obtain a recovered catalyst. That is, compared with the prior art oxidative desulfurization system in which a low eutectic solvent and a heteropolyacid coexist, the present invention can effectively separate the low eutectic solvent from the confined Anderson polymetallic oxygen cluster solid phase compound.

[0036] After drying, the activity was restored. After being reused for 5 times, the sulfur content was measured by GC-FPD, and the desulfurization rate was still greater than 99%. Figure 2 As shown, it shows that the activity is restored after each separation and washing.

[0037] 3. Application of oxidative desulfurization in commercial diesel (deep desulfurization)

[0038] Desulfurization of real diesel: A 100 mL round-bottom flask was filled with a 1:1 volume ratio of a low eutectic solvent and real diesel (commercial diesel, sulfur content 82 ppm), and placed in an oil bath at a temperature of 90 °C. o C, stirred and extracted for 30 min, and 20 mg of catalyst confined CoMo was added 6 Solid phase compound (1 / 10) was placed in a round bottom flask, oxygen flow rate was 60 mL / min, stirring and timing to start the reaction, stirring was stopped after 8 hours, after standing and stratification, 0.5-1.0 mL of the upper diesel phase was sampled in a sample bottle. The sulfur content in the crude oil sample and the oxidized diesel was determined using a sulfur analyzer.

[0039] The results show that the oxidation desulfurization rate of commercial diesel can reach 99%. The GC-FPD spectra of sulfides before and after oxidation desulfurization are shown in Figure 3 , which means that the sulfide content of diesel with an initial sulfur content of 82 ppm drops rapidly after oxidative desulfurization treatment, and the sulfide can be almost completely removed. The sulfur content of diesel after desulfurization is 0.71ppm<1ppm, reaching the index standard of deep desulfurization, and the desulfurization rate is greater than 99%.

[0040] Example 2: Confined FeMo 6 Preparation of solid phase compound (3 / 10) and its desulfurization performance

[0041] The preparation of the catalyst was similar to that in Example 1. 4 ) 3 Co(OH) 6 Mo 6 O 18 Replace with Na 3 Fe(OH) 6 Mo 6 O 18 , the molar ratio of Anderson polyoxometalate to intermediate III is 3:10.

[0042] 1. Application of oxidative desulfurization in model diesel

[0043] The prepared deep eutectic solvent is the same as that in Example 1.

[0044] Desulfurization of diesel fuel: 4 g of deep eutectic solvent and 20 mL of model diesel fuel (dibenzothiophene dissolved in decahydronaphthalene, S: 500 ppm) were added to a 100 mL three-necked round-bottom flask, respectively, and placed in an oil bath at a temperature of 90 °C. o C, stirred and extracted for 30 min, and confined FeMo 6 20 mg of solid phase compound (3 / 10) was placed in a round-bottom flask, oxygen flow rate was 60 mL / min, stirring and timing to start the reaction, stirring was stopped after 3 hours, and after standing and stratification, 0.5 mL of the upper diesel phase was sampled in a sample bottle. The sulfur content was determined by GC-FPD. The desulfurization rate reached 100%.

[0045] 2. Separation of deep eutectic solvent and catalyst

[0046] After the reaction is completed, the mixture is allowed to stand at room temperature, the upper clear oil phase is separated and poured out by decantation, and the mixture of the lower low eutectic solvent and the catalyst is transferred to a centrifuge tube, acetonitrile is added for centrifugation, washing, and separation by suction filtration to obtain the recovered catalyst. 6 Effective separation of solid phase compounds.

[0047] After drying, the activity was restored. After being reused for 5 times, the sulfur content was measured by GC-FPD, and the desulfurization rate was greater than 96%, indicating that the activity was restored after each separation and cleaning.

[0048] 3. Application of oxidative desulfurization in commercial diesel (deep desulfurization)

[0049] Real diesel (commercial diesel, sulfur content 56 ppm), limited FeMo 6 Solid phase compound, other conditions are the same as those in Example 1 for deep desulfurization test. The sulfur content in the crude oil sample and the oxidized diesel is measured by a sulfur analyzer.

[0050] The results showed that the diesel with an initial sulfur content of 56 ppm had a sulfide content of 0.9 ppm after oxidative desulfurization treatment. The sulfur content of the diesel after desulfurization was less than 1 ppm, reaching the index standard for deep desulfurization.

[0051] Example 3: Confined CrMo 6 Preparation of solid phase compound (1 / 5) and its desulfurization performance

[0052] The preparation of the catalyst was similar to that in Example 1. 4 ) 3Co(OH) 6 Mo 6 O 18 Replace with Na 3 Cr(OH) 6 Mo 6 O 18 , the molar ratio of Anderson polyoxometalate to intermediate III is 1:5.

[0053] 1. Application of oxidative desulfurization in model diesel

[0054] The prepared deep eutectic solvent is the same as that in Example 1.

[0055] Desulfurization of diesel fuel: 4 g of deep eutectic solvent and 20 mL of model diesel fuel (dibenzothiophene dissolved in decahydronaphthalene, S: 500 ppm) were added to a 100 mL three-necked round-bottom flask, respectively, and placed in an oil bath at a temperature of 90 °C. o C, stirred and extracted for 30 min, and the catalyst was added to confine CrMo 6 20 mg of solid phase compound (1 / 5) was placed in a round-bottom flask, oxygen flow rate was 60 mL / min, stirring and timing to start the reaction, stirring was stopped after 2 hours, and after standing and stratification, 0.5 mL of the upper diesel phase was sampled in a sample bottle. The sulfur content was determined by GC-FPD. The desulfurization rate reached 100%.

[0056] 2. Separation of deep eutectic solvent and catalyst

[0057] After the reaction is completed, the mixture is allowed to stand at room temperature, the upper clear oil phase is separated and poured out by decantation, and the mixture of the lower low eutectic solvent and the catalyst is transferred to a centrifuge tube, acetonitrile is added for centrifugation, washing, and separation by suction filtration to obtain a recovered catalyst. That is, this example can also effectively separate the low eutectic solvent from the confined Anderson polymetallic oxygen cluster solid phase compound.

[0058] After drying, the activity was restored. After being reused for 5 times, the sulfur content was measured by GC-FPD, and the desulfurization rate was still greater than 99%, indicating that the activity was restored after each separation and cleaning.

[0059] 3. Application of oxidative desulfurization in commercial diesel (deep desulfurization)

[0060] Real diesel (commercial diesel, sulfur content 76 ppm), limited CrMo 6 Solid phase compound, other conditions are the same as those in Example 1 for deep desulfurization test. The sulfur content in the crude oil sample and the oxidized diesel is measured by a sulfur analyzer.

[0061] The results showed that the diesel with an initial sulfur content of 76 ppm had a sulfide content of 0.7 ppm after oxidative desulfurization treatment. The sulfur content of the diesel after desulfurization was less than 1 ppm, reaching the index standard for deep desulfurization.

[0062] The present invention introduces imidazole and bromide ions by a step-by-step modification method, and then confines the polyoxometallic clusters by an ion exchange method, thereby achieving the purpose of confining the Anderson polyoxometallic clusters and changing the phase. The above experiments show that the solid-phase compound of the confined Anderson polyoxometallic clusters of the invention has excellent catalytic performance in oxidative desulfurization reactions, exhibits high reusability, and has broad application prospects. Furthermore, the solid-phase compound of the confined Anderson polyoxometallic clusters of the present invention also has excellent stability, and the catalytic activity remains unchanged even if the catalyst is washed with hot water. The reason for the analysis is that the solid-phase compound of the confined Anderson polyoxometallic clusters not only confines the polyoxometallic clusters to the pores, but also the polyoxometallic clusters undergo ion exchange with the bromide ions therein, generating electrostatic interactions, thereby improving the stability of the solid-phase compound of the confined Anderson polyoxometallic clusters.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A solid phase compound of a confined Anderson polyoxometallic cluster, characterized in that The preparation of the solid phase compound comprises the following steps: 1) Add 2-aminoterephthalic acid, chromium nitrate and sodium hydroxide in excess deionized water in a mass ratio of 1-3:2-6:1 and stir until uniformly dispersed. o After hydrothermal reaction at C for 18-24 h, the intermediate I is obtained after filtration, washing and drying; 2) The intermediate I and 1,8-diazabicycloundec-7-ene prepared in step 1) are added to excess toluene and dispersed evenly, and then N,N'-carbonyldiimidazole is added, stirred until the reaction is complete, and then filtered, washed, and dried to obtain intermediate II. Wherein, the mass ratio of the intermediate I, 1,8-diazabicycloundec-7-ene and N,N'-carbonyldiimidazole prepared in step 1) is 1000:1-5:300-400; 3) Disperse the intermediate II prepared in step 2) in toluene, slowly add n-butyl bromide at 0 °C, stir evenly, and heat at 70 o C and reflux until the reaction is complete, then filter, wash and dry to obtain intermediate III. Wherein, the mass ratio of the intermediate II prepared in step 2) to n-butyl bromide is 1:0.1-0.5; 4) After dissolving the Anderson polyoxometalate in acetonitrile, add the intermediate III prepared in step 3) and stir for 72 h until the reaction is complete. After filtering, washing and drying, the product is obtained. Among them, Anderson polymetallic oxygen cluster is (NH4)3Co(OH)6Mo6O 18 、Na3Fe(OH)6Mo6O 18 、Na3Cr(OH)6Mo6O 18 Any one of the above, the molar ratio of Anderson polyoxometalate to the intermediate III prepared in step 3) is 0.1-4:

1.

2. The solid phase compound of confined Anderson polyoxometallic clusters according to claim 1, characterized in that: The Anderson polyoxometalate in step 4) is (NH4)3Co(OH)6Mo6O 18 、Na3Fe(OH)6Mo6O 18 、Na3Cr(OH)6Mo6O 18 Any one of .

3. Use of the solid phase compound of the confined Anderson polyoxometallic cluster according to claim 1 as a catalyst for deep desulfurization of diesel.

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