A method for separating and recovering sulfides in diesel oil

Abstract

The application provides a method for separating and recovering sulfides in diesel oil, and relates to the technical field of diesel desulfurization. The method comprises the step of oxidizing desulfurization of diesel oil and an oxidizing agent under the action of a molybdenum-based catalyst. The molybdenum-based catalyst is prepared by heating and dissolving phosphomolybdic acid and triethylene glycol monomethyl ether as raw materials at 80-110 DEG C. The molar ratio of the phosphomolybdic acid and the triethylene glycol monomethyl ether is 1:3000. The method is simple. The liquid molybdenum-based catalyst obtained by heating and dissolving phosphomolybdic acid (PMA) and triethylene glycol monomethyl ether (TEGOCH3) as raw materials is used for oxidizing desulfurization. The dibenzothiophene sulfides can be efficiently removed in a short time. The diesel desulfurization efficiency and desulfurization rate are improved. The ultra-deep desulfurization of diesel oil and the efficient conversion and recovery of sulfides are realized.

Description

Technical Field

[0001] This invention relates to the field of diesel desulfurization technology, and in particular to a method for separating and recovering sulfides from diesel fuel. Background Technology

[0002] In recent years, overcapacity in oil refining and insufficient supply of chemical raw materials have become prominent structural contradictions facing my country's petrochemical industry. To address this challenge, many refining and chemical enterprises have gradually adjusted their product structure, reducing the production of refined diesel oil and converting it into fine chemicals and high-value-added chemicals such as aromatics, olefins, and green solvents, which are in short supply in the market. However, the presence of sulfides in feedstock diesel oil not only causes corrosion of production equipment but also adversely affects the quality of end products.

[0003] The most widely used desulfurization method in industry is hydrodesulfurization (HDS), which can effectively remove sulfides such as thiophene, thiols, and sulfides. However, its removal efficiency for dibenzothiophene (DBT) and its derivatives is relatively low, significantly increasing energy consumption, hydrogen consumption, and carbon emissions, and also generating large amounts of toxic H2S. It is worth noting that DBT and its derivatives are high-value-added chemicals, showing great potential and broad application prospects in the biomedical and pharmaceutical fields; its oxidation product, sulfone, is even more expensive and is also widely used in drug synthesis, organic semiconductors, and luminescent materials.

[0004] Oxidative desulfurization (ODS), a typical non-hydrodesulfurization technology, can convert DBT and its derivatives into corresponding sulfones under mild conditions. Homogeneous catalysts containing redox ionic liquids and eutectic solvents can perform one-step conversion of sulfides in diesel fuel and separate sulfone products. However, currently reported homogeneous catalysts for diesel fuel desulfurization have reaction times as long as 1.0-2.0 h, resulting in slow reaction rates, low desulfurization efficiency and rate, and an inability to efficiently remove dibenzothiophene sulfides in a short time, thus limiting diesel fuel processing capacity.

[0005] Therefore, providing a method for efficient and deep desulfurization and sulfide recovery has become an urgent technical challenge. Summary of the Invention

[0006] This invention provides a method for separating and recovering sulfides from diesel fuel. This method improves the desulfurization efficiency and desulfurization rate of diesel fuel, realizes the clean, refined and high-value utilization of diesel fuel, and the efficient recovery and conversion of sulfides, which is in line with the concept of "molecular refining".

[0007] This invention provides a method for separating and recovering sulfides from diesel fuel, comprising the step of oxidizing and desulfurizing diesel fuel and an oxidant under the action of a molybdenum-based catalyst. The molybdenum-based catalyst is prepared by heating and dissolving phosphomolybdic acid and triethylene glycol monomethyl ether at 80-110°C, wherein the molar ratio of phosphomolybdic acid to triethylene glycol monomethyl ether is 1:3000.

[0008] This invention employs a liquid molybdenum-based homogeneous catalyst obtained by heating and dissolving phosphomolybdic acid (PMA) and triethylene glycol monomethyl ether (TEGOCH3) as raw materials for oxidative desulfurization of diesel fuel. The hydroxyl groups of TEGOCH3 form hydrogen bonds with the bridging oxygen atoms of PMA, anchoring them to the PMA surface and ensuring uniform dispersion of PMA. This also facilitates the coordination of the lone pair oxygen atoms (COC) in TEGOCH3 with the Mo center at high temperatures (80-110°C), resulting in partial terminal oxygen (Mo=O) formation in the PMA. d The loss of oxygen creates oxygen vacancies, and the corresponding Mo 6+ Reduced to Mo 5+ To form a mixed valence structure Mo 6+ / Mo 5+ This is beneficial for improving electron transfer capability, thereby enhancing catalyst activity.

[0009] The molybdenum-based catalyst used in this invention has low viscosity and good flowability, which is beneficial for mass transfer, resulting in a fast desulfurization rate. It exhibits high catalytic activity in the diesel oxidative desulfurization reaction, lowering the activation energy of the oxidation reaction and promoting the oxidation of sulfides (especially dibenzothiophenes). It can rapidly convert sulfides into corresponding sulfone compounds for removal and recovery, shortening the oxidative desulfurization time from the conventional 1.0-2.0 h to 2.0-30.0 min, significantly improving desulfurization efficiency and rate. This achieves highly efficient diesel desulfurization and efficient conversion and recovery of sulfides, conforming to the "molecular refining" concept. Figure 4 As shown, oxidants (such as tert-butyl hydroperoxide, TBHP) at catalytically active sites (Mo 5+ Under the action of these reactive oxygen species, DBT is activated to form reactive oxygen species. Under the action of these reactive oxygen species, DBT is oxidized to the corresponding sulfoxides, and then further oxidized to sulfones.

[0010] Preferably, the heating temperature is 100.0°C.

[0011] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the oxidative desulfurization temperature is 70.0~90.0℃, and the reaction time is 2.0~30.0 min. When using the molybdenum-based catalyst of the present invention for catalytic oxidative desulfurization, controlling the temperature within the above range results in stronger catalytic oxidation activity and optimal desulfurization effect. This not only effectively improves the desulfurization rate but also effectively shortens the oxidative desulfurization time to 2.0~30.0 min, thereby improving desulfurization efficiency.

[0012] Preferably, the reaction time for the oxidative desulfurization is 2.0 to 12.0 min.

[0013] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the heating time during the preparation of the molybdenum-based catalyst is 1.0~4.0 h. This avoids the reaction time being too short, which could lead to the depletion of Mo... 5+ Insufficient content also avoids excessively long reaction times and increased energy consumption.

[0014] Preferably, the heating time is 3.0 h.

[0015] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the oxidative desulfurization is carried out in a microchannel reactor, the flow rate of the mixture of diesel fuel and the molybdenum-based catalyst is 1.0~8.0 mL / min, and the flow rate of the oxidant is 0.1~0.3 mL / min.

[0016] This invention has found that the flow rates of the mixture and oxidant affect the desulfurization effect of diesel fuel. Controlling the flow rates of the mixture and oxidant within the aforementioned range can effectively improve the desulfurization rate. When the material flow rate is too slow, it easily leads to insufficient mixing of diesel fuel, molybdenum-based catalyst, and oxidant, reducing the desulfurization rate; while when the material flow rate is too fast, the residence time is shortened, preventing sufficient reaction. Furthermore, an excessively fast oxidant flow rate can lead to an excess of oxidant, introducing excessive water and byproducts from oxidant decomposition, hindering the oxidation of sulfides.

[0017] Preferably, the flow rate of the mixture is 2.0~8.0 mL / min.

[0018] In some optional embodiments of the present invention, the flow rate of the mixture is controlled by a dual-channel constant flow pump, the flow rate of the oxidant is controlled by a single-channel constant flow pump, and the pipeline for conveying the mixture and the oxidant is connected by a three-channel connector and conveyed to the microchannel reactor through the three-channel connector.

[0019] Preferably, the inner diameter of the three-channel connector is 2.0 mm.

[0020] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the channel diameter of the microchannel reactor is 0.8~2.0 mm, and / or the length of the delay pipe in the microchannel reactor is 10.0~50.0 m. This facilitates control of the desulfurization reaction time, i.e., the residence time. It avoids incomplete reaction due to too short a residence time, or reduced desulfurization efficiency due to too long a residence time.

[0021] Preferably, the microchannel reactor has a channel diameter of 1.0 mm and the delay pipe has a pipe length of 30.0 m.

[0022] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the volume ratio of diesel fuel to the molybdenum-based catalyst is 1:1 to 5. Too small a proportion of the molybdenum-based catalyst will prevent ultra-deep desulfurization, while too high a proportion will increase process costs and reduce economic efficiency.

[0023] Preferably, the volume ratio of the diesel fuel to the molybdenum-based catalyst is 1:1.

[0024] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the volume ratio of diesel fuel to oxidant is 5:3 to 40:1.

[0025] The method for separating and recovering sulfides from diesel fuel according to the present invention further includes: adding water to the sulfide-containing molybdenum-based catalyst obtained by oxidative desulfurization to obtain sulfides and a water-containing molybdenum-based catalyst, wherein the volume ratio of the sulfide-containing molybdenum-based catalyst to water is 1:1 to 5. By controlling the volume ratio within this range, the sulfides can be fully precipitated in water, thereby effectively separating the sulfides from the molybdenum-based catalyst and recovering them.

[0026] The method for separating and recovering sulfides in diesel fuel according to the present invention further includes: heating and evaporating the aqueous molybdenum-based catalyst to effectively remove water by evaporation, thereby achieving the purpose of recovering the molybdenum-based catalyst.

[0027] Preferably, the heating and evaporation temperature is 80.0~110.0℃ and the time is 3.0-5.0 h.

[0028] More preferably, the heating and evaporation temperature is 100.0°C.

[0029] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the oxidant is tert-butyl hydroperoxide.

[0030] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the concentration of tert-butyl hydroperoxide is 30-70 wt.%.

[0031] Preferably, the oxidant is 70 wt.% tert-butyl hydrogen peroxide. Studies have found that when using 70 wt.% tert-butyl hydrogen peroxide as the oxidant, better desulfurization effect can be obtained under the catalytic action of the molybdenum-based catalyst of the present invention, allowing sulfides to be fully removed and recycled.

[0032] According to the method for separating and recovering sulfides from diesel fuel provided by the present invention, the sulfur content in the diesel fuel is 50.0~3000.0 mg / L. The method of the present invention is more suitable when the sulfur content in the diesel fuel is within this range. The molybdenum-based catalyst of the present invention exhibits stronger catalytic activity for the oxidative desulfurization of diesel fuel, resulting in higher desulfurization efficiency and rate.

[0033] The beneficial effects of the method for separating and recovering sulfides in diesel fuel provided by the present invention include at least the following: The method of the present invention is simple and uses a liquid molybdenum-based catalyst obtained by heating and dissolving phosphomolybdic acid (PMA) and triethylene glycol monomethyl ether (TEGOCH3) as raw materials for oxidative desulfurization. It can efficiently remove dibenzothiophene sulfides in a short time, improve the desulfurization efficiency and desulfurization rate of diesel fuel, and realize ultra-deep desulfurization of diesel fuel as well as the efficient conversion and recovery of sulfides. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a structural diagram of the high-throughput continuous system used in the method of this invention.

[0036] Figure 2 These are the density and viscosity of PMA3000.

[0037] Figure 3 The Fourier transform infrared (FT-IR) spectra of the white precipitate recovered in Example 1 and reagent grade (98%) DBTO2 are shown.

[0038] Figure 4 This is a mechanism diagram of PMA3000 catalytic oxidation desulfurization.

[0039] Figure 5 It's TEGOCH3, PMA3000 UV-Vis spectrum of PMA3000.

[0040] Figure 6 It's TEGOCH3, PMA3000 Comparison of desulfurization effects between PMA3000 and PMA3000.

[0041] Figure 7 This is a graph showing the effect of temperature on the desulfurization performance of PMA3000.

[0042] Figure 8 This is a graph showing the effect of diesel fuel containing different sulfides on the desulfurization performance of PMA3000.

[0043] Figure label: 1: Diesel feedstock storage tank; 2: Molybdenum-based catalyst storage tank; 3: Oxidant storage tank; 4: Dual-channel constant flow pump; 5: Single-channel constant flow pump; 6: T-type three-channel connector; 7: Temperature control device; 8: Microchannel reactor; 9: Material receiver; 10: Storage tank. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0045] The method for separating and recovering sulfides from diesel fuel provided by this invention can be implemented using existing devices capable of performing the corresponding functions. For example, in the embodiments of this invention, a high-throughput continuous system can be used. This system is a multi-channel continuous microchannel reactor, the structure of which is as follows: Figure 1 As shown, it includes a raw material delivery system, a microchannel reactor 8, a material receiver 9 and a storage tank 10 connected in sequence by pipelines. The storage tank 10 is used to store the molybdenum-based catalyst containing sulfides after water is added.

[0046] The raw material delivery system includes a diesel feedstock storage tank 1, a molybdenum-based catalyst storage tank 2, an oxidant storage tank 3, a dual-channel constant flow pump 4, and a single-channel constant flow pump 5. The diesel feedstock storage tank 1 and the molybdenum-based catalyst storage tank 2 are connected to the dual-channel constant flow pump 4, and the oxidant storage tank 3 is connected to the single-channel constant flow pump 5. The dual-channel constant flow pump 4 and the single-channel constant flow pump 5 are connected by a T-type three-channel connector 6, which is connected to the delay pipeline of the microchannel reactor 8. The microchannel reactor 8 is placed inside a temperature control device 7, and its channel diameter is 1.0 mm, while the length of the delay pipeline is 30.0 m.

[0047] The following examples and comparative examples illustrate the working process of separating and recovering sulfides from diesel fuel using the above-mentioned high-throughput continuous system: the temperature control device 7 is turned on and heated to the oxidation desulfurization temperature, and diesel fuel, molybdenum-based catalyst, and oxidant are added to the diesel fuel storage tank 1, the molybdenum-based catalyst storage tank 2, and the oxidant storage tank 3, respectively. Diesel fuel in diesel feedstock storage 1 and molybdenum-based catalyst in molybdenum-based catalyst storage 2 are mixed by a dual-channel constant flow pump 4. The diesel fuel and molybdenum-based catalyst are then pumped by the dual-channel constant flow pump 4 to a T-type three-channel connector 6, where they come into contact with oxidant pumped by a single-channel constant flow pump 5. After contact, they enter the delayed pipeline of microchannel reactor 8 to complete sulfide conversion and removal. The reaction product enters material receiver 9, with desulfurized diesel fuel on top and sulfide-containing molybdenum-based catalyst on the bottom. The sulfide-containing molybdenum-based catalyst is then pumped to storage tank 10, where deionized water is added to precipitate the sulfides, resulting in sulfides and a water-containing molybdenum-based catalyst. The precipitated sulfides are then recycled. Finally, storage tank 10 is placed in an oven to heat and evaporate the deionized water. The resulting molybdenum-based catalyst can then be pumped to molybdenum-based catalyst storage 2 for recycling.

[0048] There are no special restrictions on the manufacturers of the raw materials used in the molybdenum-based catalyst of this invention. Among them, Keggin-type phosphomolybdic acid (reagent grade, Mo≥47%), phosphotungstic acid, and silicotungstic acid were purchased from Maclean's; triethylene glycol monomethyl ether (≥98%) was purchased from Aladdin. Other reagents or instruments not specified by manufacturers are all conventional products or instruments that can be purchased from legitimate channels.

[0049] The diesel fuel used in the following examples and comparative examples were 500.0 mg / L DBT model diesel fuel, 4-MDBT model diesel fuel, 4,6-DMDBT model diesel fuel, and 3000.0 mg / L DBT model diesel fuel, respectively; the preparation steps are as follows: DBT model diesel fuels with concentrations of 500.0 mg / L and 3000.0 mg / L: Dibenzothiophene was dissolved in dodecane to obtain model diesel fuels with concentrations of 500.0 mg / L and 3000.0 mg / L, respectively; 500.0 mg / L 4-MDBT model diesel: 4-methyldibenzothiophene was dissolved in dodecane to obtain a model diesel with a concentration of 500.0 mg / L; 500.0 mg / L 4,6-DMDBT model diesel: 4,6-dimethyldibenzothiophene was dissolved in dodecane to obtain a model diesel with a concentration of 500.0 mg / L.

[0050] This invention uses a total sulfur and total nitrogen elemental analyzer (multi EA 5100) to detect the sulfide content in diesel fuel and desulfurized diesel fuel (named desulfurized diesel fuel), and calculates the desulfurization rate using the following formula: Desulfurization rate (%) = (sulfur content in diesel fuel - sulfur content in desulfurized diesel fuel) / sulfur content in diesel fuel × 100%.

[0051] Example 1 This embodiment provides a method for separating and recovering sulfides from diesel fuel, including the following steps: (1) A mixture of 500.0 mg / L DBT model diesel and molybdenum-based catalyst (PMA3000) in a volume ratio of 1:1 was transported to a T-type three-channel connector by a dual-channel constant flow pump at a flow rate of 2 mL / min. After contacting with tert-butyl hydrogen peroxide (concentration of 70 wt.%) controlled by a single-channel constant flow pump at a flow rate of 0.1 mL / min, it was transported to a microchannel reactor. The oxidation desulfurization temperature was controlled at 70℃ and the reaction time was 11.21 min to carry out oxidation desulfurization and obtain desulfurization products. The upper layer of the desulfurization products was desulfurized diesel and the lower layer was molybdenum-based catalyst containing sulfides. (2) Add deionized water to the molybdenum-based catalyst containing sulfide at a volume ratio of 1:3. A white precipitate is precipitated. The white precipitate is centrifuged (10,000 rpm, 3 min), washed with water and filtered (3 times), and then dried (60℃) to recover the sulfide and the water-containing molybdenum-based catalyst. (3) The water-containing molybdenum-based catalyst is heated at 100°C for 4 h until the water evaporates to obtain the molybdenum-based catalyst, which is then recycled.

[0052] The preparation method of the molybdenum-based catalyst is as follows: Weigh 0.0608 g of Keggin-type phosphomolybdic acid (PMA) and 16.4200 g of triethylene glycol monomethyl ether at a molar ratio of 1:3000 into a 20 mL glass bottle. Heat the mixture in an oil bath to 100°C and stir for 3 h. Remove the bottle from the oil bath and cool to room temperature to obtain a molybdenum-based catalyst, named PMA3000. Its density and viscosity are as follows: Figure 2 As shown.

[0053] Figure 3 Both the white precipitate and reagent-grade (98%) DBTO2 showed characteristic peaks attributable to S=O in FT-IR, indicating that the white precipitate was DBTO2. This demonstrates that the molybdenum-based catalyst of this invention can effectively remove and recover dibenzothiophene sulfides from diesel fuel through catalytic oxidative desulfurization. The mechanism of its catalytic oxidative desulfurization is as follows: Figure 4 As shown.

[0054] Example 2 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the temperature for oxidative desulfurization is 80°C.

[0055] Example 3 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the oxidation desulfurization temperature is 80°C, the flow rate of the mixture controlled by the dual-channel constant flow pump is 4.0 mL / min, and the reaction time for oxidation desulfurization is 5.74 min.

[0056] Example 4 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the oxidation desulfurization temperature is 90°C, the flow rate of the mixture controlled by the dual-channel constant flow pump is 6.0 mL / min, and the reaction time for oxidation desulfurization is 3.86 min.

[0057] Example 5 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the oxidation desulfurization temperature is 90°C, the flow rate of the mixture controlled by the dual-channel constant flow pump is 8.0 mL / min, the flow rate of tert-butyl hydrogen peroxide controlled by the single-channel constant flow pump is 0.2 mL / min, and the reaction time for oxidation desulfurization is 2.87 min.

[0058] Example 6 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the oxidation desulfurization temperature is 90°C, the flow rate of the mixture controlled by the dual-channel constant flow pump is 8.0 mL / min, the flow rate of tert-butyl hydroperoxide controlled by the single-channel constant flow pump is 0.3 mL / min, and the reaction time for oxidation desulfurization is 2.83 min.

[0059] Example 7 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that the oxidation desulfurization temperature is 80°C and 500.0 mg / L of 4-MDBT model diesel fuel is used for oxidation desulfurization.

[0060] Example 8 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the oxidation desulfurization temperature is 80°C and oxidative desulfurization is performed using 4,6-DMDBT model diesel fuel with a sulfur content of 500.0 mg / L.

[0061] Example 9 This embodiment provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Embodiment 1, except that the oxidation desulfurization temperature is 90°C and DBT model diesel fuel with a sulfur content of 3000.0 mg / L is used for oxidation desulfurization.

[0062] Comparative Example 1 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that an equal volume of PMA3000 is replaced with PMA3000. ; PMA3000 The preparation method is as follows: phosphomolybdic acid and triethylene glycol monomethyl ether are dissolved at a molar ratio of 1:3000 at room temperature to obtain a molybdenum-based catalyst, named PMA3000. .

[0063] Comparative Example 2 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that PMA3000 is replaced by TEGOCH3 in equal volumes.

[0064] Comparative Example 3 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that the molar ratio of phosphomolybdic acid and triethylene glycol monomethyl ether is 1:5000 when preparing the molybdenum-based catalyst; the resulting molybdenum-based catalyst is named PMA5000.

[0065] Comparative Example 4 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that the molar ratio of phosphomolybdic acid and triethylene glycol monomethyl ether is 1:500 when preparing the molybdenum-based catalyst; the resulting molybdenum-based catalyst is named PMA500.

[0066] Comparative Example 5 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that when preparing the molybdenum-based catalyst, the content of triethylene glycol monomethyl ether is replaced with polyethylene glycol monomethyl ether 200; the resulting molybdenum-based catalyst is named PMA3000-200PEGOCH3.

[0067] Comparative Example 6 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that when preparing the molybdenum-based catalyst, the content of triethylene glycol monomethyl ether is replaced with polyethylene glycol monomethyl ether 550; the resulting molybdenum-based catalyst is named PMA3000-550PEGOCH3.

[0068] Comparative Example 7 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that when preparing the homogeneous catalyst, the Keggin-type phosphomolybdic acid is replaced with Keggin-type phosphotungstic acid (PWA); the resulting homogeneous catalyst is named PWA3000.

[0069] Comparative Example 8 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that when preparing the homogeneous catalyst, the Keggin-type phosphomolybdic acid is replaced with Keggin-type silicotungstic acid (SiWA); the resulting homogeneous catalyst is named SiWA3000.

[0070] Comparative Example 9 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that the heating temperature is 70°C when preparing the molybdenum-based catalyst.

[0071] Comparative Example 10 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that the temperature for oxidative desulfurization is 60°C.

[0072] Comparative Example 11 This comparative example provides a method for separating and recovering sulfides from diesel fuel, which is basically the same as that in Example 1, except that the oxidation desulfurization temperature is 90°C, the flow rate of the mixture controlled by the dual-channel constant flow pump is 10.0 mL / min, the flow rate of tert-butyl hydroperoxide controlled by the single-channel constant flow pump is 0.3 mL / min, and the reaction time for oxidation desulfurization is 2.29 min.

[0073] The desulfurization rate test results of diesel fuel obtained by the method in this embodiment are shown in Table 1:

[0074] The results of the comparative method for detecting the desulfurization rate of diesel fuel are shown in Table 2:

[0075] As shown in Table 1, Examples 1-9 use the method of the present invention to separate and recover sulfides from diesel fuel. The desulfurization rate of diesel fuel is as high as 98% or more, and the sulfur content in diesel fuel is no higher than 10.0 mg / L, achieving ultra-deep desulfurization and sulfide recovery.

[0076] The difference between Example 1, Comparative Example 1, and Comparative Example 2 is that the molybdenum-based catalysts used are PMA3000 and PMA3000, respectively. The UV-Vis spectra of these three molybdenum-based catalysts, including TEGOCH3, are shown below. Figure 5 As shown in the figure, the corresponding desulfurization effect comparison chart is as follows: Figure 6 As shown. By Figure 5 It can be seen that the PMA3000 exhibited Mo 5+ The characteristic peaks indicate that part of Mo 6+ It was restored. Therefore, PMA3000 is better than PMA3000. TEGOCH3 has a stronger electron transfer capability, making it highly active in catalytic oxidation reactions, thereby improving the desulfurization rate. Figure 6 As shown in Tables 1 and 2, the desulfurization rate of Example 1 is significantly higher than that of Comparative Example 1 and Comparative Example 2, and the sulfur content of the desulfurized diesel is significantly lower than that of Comparative Example 1 and Comparative Example 2.

[0077] Comparing Example 1 and Comparative Example 3-11, it can be seen that the desulfurization rate of Comparative Example 3-11 is lower than that of Example 1. This indicates that the molar ratio of phosphomolybdic acid and triethylene glycol monomethyl ether in the preparation of the molybdenum-based catalyst, as well as the heating temperature, need to be controlled within a suitable range to effectively improve the desulfurization rate. Furthermore, replacing either phosphomolybdic acid or triethylene glycol monomethyl ether with other substances cannot achieve the effect of ultra-deep desulfurization, and greatly reduces the desulfurization rate.

[0078] The effect of different oxidative desulfurization reaction temperatures (70℃ in Example 1 and 80℃ in Example 2, and 60℃ in Comparative Example 10) on the diesel desulfurization effect is as follows: Figure 7 As shown. The effects of diesel fuels containing different sulfides (DBT model diesel fuel of Example 1, 4-MDBT model diesel fuel of Example 7, and 4,6-DMDBT model diesel fuel of Example 8) on the diesel fuel desulfurization effect are as follows. Figure 8 As shown. By Figure 7 and Figure 8 It is known that good desulfurization effect can be achieved when the oxidation desulfurization temperature is between 70-80℃, and the method of the present invention can achieve ultra-deep desulfurization effect for diesel containing different sulfides, and its applicability is wide.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for separating and recovering sulfides from diesel fuel, characterized in that, The method includes the step of oxidizing and desulfurizing diesel fuel and oxidant under the action of a molybdenum-based catalyst, wherein the molybdenum-based catalyst is prepared by heating and dissolving phosphomolybdic acid and triethylene glycol monomethyl ether at 80~110°C, and the molar ratio of phosphomolybdic acid and triethylene glycol monomethyl ether is 1:3000. The oxidation desulfurization temperature is 70.0~90.0℃, and the reaction time is 2.0~30.0 min; The oxidative desulfurization is carried out in a microchannel reactor; The flow rate of the mixture of diesel oil and the molybdenum-based catalyst is 1.0~8.0 mL / min, and the flow rate of the oxidant is 0.1~0.3 mL / min.

2. The method for separating and recovering sulfides from diesel fuel according to claim 1, characterized in that, The heating time during the preparation of the molybdenum-based catalyst is 1.0~4.0 h.

3. The method for separating and recovering sulfides from diesel fuel according to claim 1 or 2, characterized in that, The microchannel reactor has a channel diameter of 0.8 to 2.0 mm, and / or the delay pipe in the microchannel reactor has a length of 10.0 to 50.0 m.

4. The method for separating and recovering sulfides from diesel fuel according to claim 1 or 2, characterized in that, The volume ratio of the diesel fuel to the molybdenum-based catalyst is 1:1 to 5.

5. The method for separating and recovering sulfides from diesel fuel according to claim 1 or 2, characterized in that, Also includes: Water is added to the molybdenum-based catalyst containing sulfides obtained by the aforementioned oxidative desulfurization to obtain sulfides and water-containing molybdenum-based catalysts, wherein the volume ratio of the molybdenum-based catalyst containing sulfides to water is 1:1~5.

6. The method for separating and recovering sulfides from diesel fuel according to claim 1 or 2, characterized in that, The oxidant is tert-butyl hydroperoxide.

7. The method for separating and recovering sulfides from diesel fuel according to claim 6, characterized in that, The concentration of the tert-butyl hydroperoxide is 30~70 wt.%.

8. The method for separating and recovering sulfides from diesel fuel according to claim 1 or 2, characterized in that, The sulfur content in the diesel fuel is 50.0~3000.0 mg / L.

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