Preparation method of oxygen vacancy-enriched double-phase tungsten oxide WO3H2O / WO2.72 and application of oxygen vacancy-enriched double-phase tungsten oxide WO3H2O / WO2.72 in olefin epoxidation
The oxygen vacancy-rich dual-phase tungsten oxide WO3·H2O/WO2.72 was prepared by solvothermal reaction, which solved the problem of complex oxygen vacancy regulation in tungsten oxide in the existing technology and achieved efficient olefin epoxidation catalysis, especially for chemically inactive olefins.
Patent Information
- Application Number
- CN202510967827.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-14
- Publication Date
- 2025-10-17
AI Technical Summary
The existing technology is complex and inefficient in the process of introducing oxygen vacancies into tungsten oxide. The existing methods are relatively complex and it is difficult to achieve the crystal form and phase transformation of tungsten oxide to regulate the oxygen vacancy concentration, and there is little research on tungsten oxide.
Oxygen vacancy-rich dual-phase tungsten oxide WO3·H2O/WO2.72 was prepared via a solvothermal reaction. By controlling the raw material ratio and synthesis time, a flower-like nano-hierarchical structure was formed to achieve a high concentration of oxygen vacancies and a large specific surface area. The optimal conditions were selected by combining typical olefin epoxidation reactions.
The simple and easy-to-operate regulation of oxygen vacancy concentration was achieved, and the activity of the tungsten oxide catalyst was improved, especially in the epoxidation reaction of olefins, which showed a highly efficient catalytic effect and also had significant catalytic activity for chemically inactive olefins.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of tungsten oxide catalysts, in particular to a preparation method of an oxygen vacancy-rich biphase tungsten oxide WO3•H2O / WO 2.72 and its application in olefin epoxidation. The deep blue biphase tungsten oxide WO3•H2O / WO 2.72 prepared by the present application has a flower-like nano hierarchical structure, in which WO3•H2O and WO 2.72 two phases coexist, the W 5+ content reaches 9-15%, the oxygen vacancy content reaches 15-25%, and the specific surface area is 35-90 m 2 / g. BACKGROUND
[0002] Metal oxides have an irreplaceable position in the field of heterogeneous catalysis due to their unique electronic structure, controllable surface active sites and environmentally friendly characteristics. Oxygen vacancies are key intrinsic defects of metal oxides, which can adjust the electronic structure and promote the adsorption and activation of reactants, that is, oxygen vacancies can act as active sites of metal oxides to promote the improvement of catalytic activity. Therefore, the method of introducing appropriate oxygen vacancies into metal oxides through defect engineering to improve the activity of catalysts has attracted more and more attention of researchers. So far, various methods for introducing oxygen vacancies have been developed, such as high-temperature pyrolysis, ion doping and high-energy ion bombardment. However, the implementation process of these methods is often complex, and it is of great significance to find a simpler and more effective method for introducing oxygen vacancies to control the activity of catalysts.
[0003] Metal oxide catalysts generally exist in the form of crystals, and the crystal form and phase of the crystals change with the environment. Different crystal forms and phases have different atomic structures, which means that the intrinsic oxygen vacancy concentration will change. Therefore, controlling the conditions to make the metal oxides dynamically restructure (crystal transformation) during the growth process and interrupting the process with more oxygen vacancies is likely to become a powerful means of introducing oxygen vacancies. Current studies have found that the transformation of TiO2 from anatase to rutile by electron beam irradiation or the transformation of ZrO2 from monoclinic to tetragonal phase at different temperatures increases the oxygen vacancies, indicating that the crystal transformation process can regulate the oxygen vacancies. However, there are few studies on introducing oxygen vacancies into tungsten oxides by crystal transformation, and the above-mentioned crystal transformation conditions of TiO2 and ZrO2 are still relatively harsh.
[0004] The stoichiometric form of tungsten oxide is WO3, which has multiple crystal forms such as hexagonal, monoclinic, orthorhombic and tetragonal. In addition, there are WO 2.72 , WO 2.8 , WO 2.83 and WO 2.9and WO3•0.33H2O, WO3•0.5H2O and WO3•2H2O. For such a polymorphous metal oxide, the application provides a simple and easy-to-operate method for changing the crystal type while changing the oxygen vacancy concentration, and the optimal oxygen vacancy concentration and crystal type are selected in combination with a typical epoxidation reaction to determine the optimal preparation conditions, which has practical significance for establishing the correspondence between the crystal structure of tungsten oxide and the oxygen vacancy and preparing a high-activity tungsten oxide-based epoxidation catalyst.
[0005] Therefore, in view of the purpose of introducing oxygen vacancies, the tungsten oxide catalyst is deeply researched, and the preparation process is focused on, and the tungsten oxide catalyst with rich oxygen vacancies is prepared by optimizing the proportion of raw materials and controlling the synthesis time in a simple step. SUMMARY
[0006] The application provides a preparation method of a dual-phase tungsten oxide WO3•H2O / WO 2.72 and application of the dual-phase tungsten oxide in olefin epoxidation.
[0007] The preparation method of the dual-phase tungsten oxide WO3•H2O / WO 2.72 of the application comprises the following steps: WCl6 and anhydrous ethanol are placed in a container in a proportion of 0.003-0.005:1 by mole ratio, and stirred until completely dissolved, the solution is transferred into a self-pressure reaction kettle, and is subjected to a solvent thermal reaction at 120-160 DEG C under the condition of dynamic stirring at 40-100 r / min for 7-11 h, and then is cooled to room temperature, centrifuged or suction filtered, and the obtained product is sequentially washed with pure water and anhydrous ethanol for 3-4 times, and is dried at 40-80 DEG C for 3-10 h, so that the dual-phase tungsten oxide WO3•H2O / WO 2.72 of the application with a flower-like nano hierarchical structure is obtained. 2.72 The two phases of WO3•H2O and WO 5+ coexist, the W content reaches 9-15%, the oxygen vacancy content reaches 15-25%, and the specific surface area is 35-90 m 2 / g.
[0008] In the application, the WCl6 is an analytical pure reagent with a mass fraction of ≥99.9%, and the anhydrous ethanol is an analytical pure reagent with a mass fraction of ≥99.5%.
[0009] Preferably, in the preparation method, the reaction temperature is 135-145 DEG C, the reaction time is 10 h, and the dynamic stirring rate is 45-60 r / min, so that the WO3•H2O and WO 2.72Two phases coexist. The stirring can use oil bath magnetic stirring, or the reaction kettle can be fixed in the homogeneous reactor to realize the rotation stirring.
[0010] Preferably, in the above preparation method, the drying temperature is 50-60 DEG C, and the drying time is 4-6 h.
[0011] The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO 2.72 In the application of olefin epoxidation reaction.
[0012] The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO 2.72 In the application of olefin epoxidation reaction, the dual-phase tungsten oxide WO3•H2O / WO 2.72 For the epoxidation reaction of cyclooctene, cyclohexene, 1-hexene, 1-octene, 1-decene, 1-dodecene.
[0013] The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO 2.72 In the application of olefin epoxidation reaction, the dual-phase tungsten oxide WO3•H2O / WO 2.72 For the epoxidation reaction of cyclooctene, specifically comprising the following steps: 10 ml acetonitrile is added in a 15 mL reaction kettle, then 30 mg dual-phase tungsten oxide WO3•H2O / WO 2.72 , 4 mmol cyclooctene and 4 mmol 30% H2O2 by mass fraction are added therein, after ultrasonic dispersion for 2 min, it is sealed, and is reacted for 6 h under the condition of 60 DEG C and 400 r / min water bath stirring, after natural cooling, the internal standard anisole is added for quantification by using a gas chromatograph, the conversion rate of cyclooctene is greater than 96%, and the selectivity of epoxycyclooctane is greater than 99%.
[0014] The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO 2.72 In the application of olefin epoxidation reaction, the dual-phase tungsten oxide WO3•H2O / WO 2.72 For the epoxidation reaction of 1-octene of chemical passivity, specifically comprising the following steps: 10 ml acetonitrile is added in a 15 mL reaction kettle, then 30 mg dual-phase tungsten oxide WO3•H2O / WO 2.72 , 4 mmol 1-octene and 4 mmol 30% H2O2 by mass fraction are added therein, after ultrasonic dispersion for 2 min, it is sealed, the reaction kettle is fixed on a homogeneous reactor, and is reacted for 4 h under the condition of 60 DEG C and 25 r / min rotation, after natural cooling, the internal standard anisole is added for quantification by using a gas chromatograph, the conversion rate of 1-octene is greater than 52%, and the selectivity of 1,2-epoxycyclooctane is greater than 61%.
[0015] The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO of the present invention 2.72 The preparation method is simple and the preparation principle is as follows: At a certain concentration and temperature, the tungsten source first forms a flower-like nanostructure of orthorhombic WO3•H2O phase with good crystallinity through solvothermal reaction (nanosheets self-assemble into flower-like structures); as the reaction time increases, WO3•H2O gradually loses its crystal water to form a monoclinic WO 2.72 Phase transition, crystal phase transition process, the flower-like hierarchical structure is also gradually changing, which is manifested in the appearance of nanoparticles (monoclinic WO) on the nanosheets (orthorhombic WO3•H2O). 2.72 ), when WO3•H2O is completely transformed into WO 2.72 When , the nanosheets are composed of nanoparticles.
[0016] Crystal phase and morphology transformation during the solvothermal preparation process: before 6 hours, it is a single orthorhombic WO3•H2O phase, and the morphology is a flower-like hierarchical structure assembled by nanosheets. After 6 hours, monoclinic WO 2.72 phase, namely WO3•H2O / WO 2.72 The duration of the two-phase coexistence with good olefin epoxidation catalytic activity was 7-11 h. During this stage, the morphology changed to the gradual appearance of nanoparticles on the nanosheets. At 12 h, WO3•H2O was completely converted into WO 2.72 At this time, the nanosheets are completely composed of nanoparticles, and the hierarchical structure has some collapse. 2.72 It is a coordination unsaturated structure, so the oxygen vacancies and W 5+ The content continues to increase.
[0017] Epoxidation activity: The epoxidation activity of the samples aged 2-12 h first increased and then decreased, reaching a peak at 10 h and then starting to decrease from 11 h. The main reason is that the sample aged 10 h has the largest specific surface area, high oxygen vacancy concentration and dual-phase WO3•H2O / WO 2.72 From 2 to 6 h, only a single phase of WO3•H2O with few oxygen vacancies and a small specific surface area was formed. From 6 to 7 h, although a dual phase was present, the oxygen vacancy content and specific surface area were still small. From 11 to 12 h, although more oxygen vacancies were present and the dual phase still existed, the structures of the two phases began to collapse, resulting in a smaller specific surface area. Therefore, the products at these times had lower activity. The products from 7 to 11 h had better catalytic activity for olefin epoxidation.
[0018] Compared with the prior art, the present invention has the following advantages: (1) Through a large number of experimental and theoretical studies, it was determined that the hydrated tungsten oxide WO3•H2O undergoes a phase transition during its preparation process. The preparation conditions are simple, easy to operate, and has good reproducibility. (2) In-depth study of the preparation process of WO3•H2O / WO 2.72 the time reaction conditions, and the relationship between the concentration of W 5+ and oxygen vacancy, it is clear that the high oxygen vacancy, large specific surface area and polycrystalline phase have a promoting effect on the olefin epoxidation reaction when the reaction time is 7-11 h, and the sample has the best catalytic effect on the olefin epoxidation reaction when the reaction time is 10 h; (3) The preparation of other dual-phase or multi-phase tungsten oxide and its catalytic activity provide a reference.
[0019] The present application obtains a dual-phase tungsten oxide with rich oxygen vacancies by changing the solvothermal synthesis time in the preparation of WO3•H2O through a simple solvothermal reaction, which is mild in conditions and simple in operation, realizes the change of oxygen vacancy concentration through the change of crystal type and phase, and forms a dual-phase tungsten oxide WO3•H2O / WO 2.72 The optimal preparation conditions are determined by combining the typical epoxidation reaction to select the optimal oxygen vacancy concentration and crystal type, which has a reference significance for establishing the corresponding relationship between the crystal structure of tungsten oxide and the oxygen vacancy, and preparing a high-activity epoxidation tungsten-based epoxidation catalyst, and is suitable for wide promotion. In addition, it is found through experimental research that the dual-phase tungsten oxide prepared by the method can also effectively promote the epoxidation of chemically inert olefins, which also points out the direction for the research of epoxidation catalysts for chemically inert olefins. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 The X-ray diffraction pattern of the dual-phase tungsten oxide WO3•H2O / WO 2.72 prepared in Example 1 is shown in the figure; Figure 2 The scanning electron microscope photo of the dual-phase WO3•H2O / WO 2.72 prepared in Example 1 is shown in the figure; Figure 3 The high-resolution transmission electron microscope photo of the dual-phase WO3•H2O / WO 2.72 prepared in Example 1 is shown in the figure; Figure 4 The X-ray diffraction pattern of the dual-phase tungsten oxide WO3•H2O / WO 2.72 prepared in Example 2 is shown in the figure; Figure 5 The scanning electron microscope photo of the dual-phase tungsten oxide WO3•H2O / WO 2.72 prepared in Example 2 is shown in the figure; Figure 6 The X-ray diffraction pattern of the dual-phase tungsten oxide WO3•H2O / WO 2.72 prepared in Example 3 is shown in the figure; Figure 7 The dual-phase tungsten oxide WO3•H2O / WO prepared in Example 1 in Example 4 2.72 Chromatogram at the end of the catalytic cyclooctene epoxidation reaction; Figure 8 The dual-phase tungsten oxide WO3•H2O / WO prepared in Example 1 in Example 4 2.72 Result diagram of catalytic epoxidation of cyclooctene; Figure 9 The dual-phase tungsten oxide WO3•H2O / WO prepared in Example 1 in Example 5 2.72 Result diagram of catalytic epoxidation of 1-octene; Figure 10 The dual-phase tungsten oxide WO3•H2O / WO prepared in Example 6 2.72 X-ray diffraction pattern of; Figure 11 The dual-phase tungsten oxide WO3•H2O / WO prepared in Example 7 2.72 X-ray diffraction pattern of; Figure 12 The dual-phase tungsten oxide WO3•H2O / WO prepared in Example 3 in Example 8 2.72 Results of catalytic epoxidation of 1-dodecene. DETAILED DESCRIPTION
[0021] In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments. The following embodiments are merely exemplary illustrations of the technical solution of the present invention and do not limit the present invention in any form. Example
[0022] The dual-phase tungsten oxide WO3•H2O / WO rich in oxygen vacancies in this embodiment 2.72 The preparation method comprises the following steps: 4 mmol WCl6 (1.58 g) and 60 ml anhydrous ethanol (1 mol) were placed in a beaker and magnetically stirred until completely dissolved. The solution was transferred to a 100 ml reactor and subjected to solvent thermal reaction at 140 °C with dynamic rotary stirring at 50 r / min for 10 h. After cooling to room temperature, the product was filtered and washed three times with pure water and anhydrous ethanol respectively. It was dried at 70 °C for 4 h to obtain a dark blue dual-phase tungsten oxide WO3•H2O / WO with a flower-like nano-hierarchical structure. 2.72 .
[0023] Take the dual-phase tungsten oxide WO3•H2O / WO prepared in this example 2.72 The results obtained by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy are as follows: Figure 1 、Figure 2 and Figure 3 It can be seen from Figure 1 that the 10h sample contains two crystal forms and crystal phases, which are orthorhombic WO3•H2O phase and monoclinic WO 2.72 phase respectively, wherein the (111), (200), (202), (222), (311) crystal faces belong to orthorhombic WO3•H2O; the (010) and (020) crystal faces belong to monoclinic WO 2.72 It can be seen from the diffraction intensities of (010) and (111) that the contents of the two crystal phases are equivalent at this time. Figure 2 It can be seen from Figure 3 that the selected area diffraction of the sample presents two sets of spots, wherein (111) and (200) belong to orthorhombic WO3•H2O, and (010) belongs to monoclinic WO 2.72 In addition, the A area is the particle on the nanosheet, and the lattice fringe spacing is 0.38 nm, which belongs to the (010) face of monoclinic WO 2.72 The lattice fringes of the base B and C areas are 0.34 nm and 0.26 nm respectively, which belong to the (111) and (200) faces of orthorhombic WO3•H2O respectively. The X-ray diffraction and high-resolution transmission electron microscopy results fully show that the product is a two-phase coexisting sample.
[0024] W 5+ and oxygen vacancy concentrations are characterized by X-ray photoelectron spectroscopy and calculated by peak area, and the W 5+ and oxygen vacancy concentrations of the two-phase product are 13.6% and 23.5% respectively, and the surface area calculated by nitrogen adsorption and desorption is 87.8 m 2 / g. Example
[0025] Take 3 mmol WCl6 (1.19 g) and 60 ml anhydrous ethanol (1 mol) in a beaker, and magnetically stir until completely dissolved. Transfer the solution into a 100 ml hydrothermal reactor, and keep dynamic rotation stirring at 70 r / min under solvothermal reaction at 150 ℃ for 9 h. After cooling to room temperature, suction filtration, and washing the obtained product with pure water and anhydrous ethanol for 3 times respectively, and drying at 60 ℃ for 7 h, a deep blue two-phase tungsten oxide WO3•H2O / WO 2.72 is obtained with flower-like nano hierarchical structure.
[0026] The product prepared in this example is studied by X-ray diffraction and scanning electron microscopy, and the obtained results are shown in Figure 4 and Figure 5 respectively. From Figure 4It can be seen that the product still exists in two phases (orthorhombic WO3•H2O phase and monoclinic WO 2.72 phase), and from the diffraction intensity of (010) and (111), it can be seen that the orthorhombic WO3•H2O is the main crystal phase.
[0027] The X-ray photoelectron spectroscopy characterization and peak area calculation of the obtained two-phase product show that the W 5+ and oxygen vacancy concentrations are 12.1% and 19.7%, respectively, and the surface area calculated by nitrogen adsorption and desorption is 50.6 m 2 / g. Embodiment
[0028] Take 5 mmol WCl6 (1.98 g) and 60 ml of anhydrous ethanol (1 mol) and place them in a beaker, magnetically stir until completely dissolved, and then transfer the solution to a 100 ml hydrothermal reactor. Keep the dynamic rotation stirring at 40 r / min under solvothermal reaction at 160 ℃ for 11 h. After cooling to room temperature, suction filtration, and then washing the obtained product with pure water and anhydrous ethanol for 3 times respectively, and drying at 80 ℃ for 3 h, a deep blue two-phase tungsten oxide WO3•H2O / WO 2.72 is obtained.
[0029] The X-ray diffraction results of the product prepared in this embodiment are shown in Figure 6 From the figure, it can be seen that the product still exists in two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 2.72 phase), and from the diffraction intensity of (010) and (111), it can be seen that the monoclinic WO 2.72 has become the main crystal phase, so the (111) face double peak (222) diffraction peak of the orthorhombic WO3•H2O no longer appears.
[0030] The X-ray photoelectron spectroscopy characterization and peak calculation of the obtained two-phase product show that the W 5+ and oxygen vacancy concentrations are 14.1% and 24.8%, respectively, and the surface area calculated by nitrogen adsorption and desorption is 68.4 m 2 / g. Embodiment
[0031] The two-phase tungsten oxide WO3•H2O / WO 2.72 prepared by the method of embodiment 1 is used for the epoxidation reaction of cyclooctene, which specifically includes the following steps: 10 ml of acetonitrile is added to a 15 mL reactor, and then 30 mg of two-phase tungsten oxide WO3•H2O / WO 2.72, 4 mmol of cyclooctene and 4 mmol of 30% H2O2 by mass were added, and after ultrasonic dispersion for 2 min, the reaction was closed, and the reaction was carried out at 60 ℃ under 400 r / min water bath stirring for 6 h. After natural cooling, an internal standard anisole was added for quantification by a gas chromatograph.
[0032] The chromatogram of the sample taken after the catalytic epoxidation reaction was completed is shown in Figure 7 , and the catalytic results are shown in Figure 8 . It can be seen that the dual-phase WO3•H2O / WO 2.72 The conversion rate of cyclooctene is greater than 96%, and the selectivity of epoxycyclooctane is greater than 99%. Example
[0033] The dual-phase tungsten oxide WO3•H2O / WO 2.72 prepared by the method of Example 1 was used for the epoxidation reaction of chemically passivated 1-octene, which specifically included the following steps: 10 ml of acetonitrile was added to a 15 mL reaction kettle, and then 30 mg of the dual-phase tungsten oxide WO3•H2O / WO 2.72 , 4 mmol of 1-octene and 4 mmol of 30% H2O2 by mass were added, and after ultrasonic dispersion for 2 min, the reaction was closed. The reaction kettle was fixed on a homogeneous reactor, and the reaction was carried out at 60 ℃ under 25 r / min rotation for 4 h. After natural cooling, an internal standard anisole was added for quantification by a gas chromatograph.
[0034] The catalytic epoxidation results are shown in Figure 9 . It can be seen that the dual-phase WO3•H2O / WO 2.72 of Example 1 has a conversion rate of 1-octene greater than 52% and a selectivity of 1,2-epoxycyclooctane greater than 61%, indicating that the dual-phase tungsten oxide WO3•H2O / WO 2.72 prepared by the method of the present application still has very good catalytic activity for the epoxidation catalytic reaction of chemically passivated olefins. Example
[0035] Take 3.5 mmol of WCl6 (1.38 g) and 60 ml of anhydrous ethanol (1 mol), and place them in a beaker. Stir magnetically until completely dissolved. Transfer the solution to a 100 ml hydrothermal reaction kettle. Perform solvothermal reaction at 130 ℃ under dynamic rotation stirring at 80 r / min for 7 h. After cooling to room temperature, perform suction filtration. Wash the obtained product with pure water and anhydrous ethanol for 3 times respectively. Dry at 60 ℃ for 8 h to obtain the deep blue dual-phase tungsten oxide WO3•H2O / WO 2.72 .
[0036] Take the product prepared in this example to perform X-ray diffraction, and the results are shown in Figure 10As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 2.72 As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 2.72 As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 5+ As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 2 / g. Example 3
[0037] Take 4.5 mmol WCl6 (1.78g), and 60 ml of anhydrous ethanol (1 mol), placed in a beaker, magnetic stirring to completely dissolved, the solution into 100 ml hydrothermal reactor, at 140 ℃, keep 60 r / min dynamic rotation stirring under solvothermal reaction 10 h, cooled to room temperature, suction filtration, the product obtained in turn with pure water and anhydrous ethanol were washed 3 times, 40 ℃ under drying 10 h, obtained with flower-like nano hierarchical structure of deep blue two-phase tungsten oxide WO3•H2O / WO 2.72 .
[0038] The X-ray diffraction results of the product prepared in this example are shown in Figure 11 As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 2.72 As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 5+ As shown in the figure, the product also has two crystal phases (orthorhombic WO3•H2O phase and monoclinic WO 2 / g. Example 3
[0039] The two-phase tungsten oxide WO3•H2O / WO 2.72 prepared by the method of example 3 is used for the epoxidation reaction of chemical passivity 1-dodecene, which specifically includes the following steps: in 15 mL of the reactor, 10 ml of acetonitrile is added, then 30 mg of two-phase tungsten oxide WO3•H2O / WO 2.72, 4 mmol of 1-dodecene and 4 mmol of 30% mass fraction H2O2 were added, and after ultrasonic dispersion for 2 min, the reaction kettle was fixed on a homogeneous reactor, and the reaction was carried out at 60 ℃ under the condition of 25 r / min rotation for 4 h. After natural cooling, an internal standard anisole was added for quantification by a gas chromatograph.
[0040] The catalytic epoxidation results are shown in Table 3. Figure 12 As can be seen from Table 3, the conversion rate of 1-dodecene is greater than 46.6%, and the selectivity of 1,2-epoxydodecane is greater than 67.1%. 2.72 The conversion rate of 1-dodecene is greater than 46.6%, and the selectivity of 1,2-epoxydodecane is greater than 67.1%.
Claims
1. Oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO 2.72 The preparation method is characterized in that The method comprises the following steps: placing WCl6 and anhydrous ethanol in a molar ratio of 0.003-0.005:1 in a container, stirring until completely dissolved, transferring the solution into a self-pressurized reactor, performing a solvent thermal reaction at 120-160°C and maintaining a dynamic stirring of 40-100 r / min for 7-11 hours, cooling to room temperature, centrifuging or filtering, washing the obtained product with pure water and anhydrous ethanol for 3-4 times respectively, and drying at 40-80°C for 3-10 hours to obtain a dark blue dual-phase tungsten oxide WO3•H2O / WO with a flower-like nano-hierarchical structure. 2.72 , among which WO3•H2O and WO 2.72 Two-phase coexistence, W 5+ The content reaches 9-15%, the oxygen vacancy content reaches 15-25%, and the specific surface area is 35-90 m 2 / g.
2. The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO according to claim 1 2.72 The preparation method is characterized in that: The WCl6 is an analytically pure reagent with a mass fraction of ≥99.9%, and the anhydrous ethanol is an analytically pure reagent with a mass fraction of ≥99.5%.
3. The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO according to claim 1 2.72 The preparation method is characterized in that: The molar ratio of WCl6 and anhydrous ethanol was 0.004:1, the reaction temperature was 135-145 ℃, the reaction time was 10 h, and the dynamic stirring rate was 45-60 r / min. The prepared WO3•H2O and WO 2.72 The two phases coexist.
4. The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO according to claim 1 2.72 The preparation method is characterized in that: The drying temperature is 50-60 ℃ and the drying time is 4-6 h.
5. Oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO 2.72 Application in olefin epoxidation.
6. The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO according to claim 5 2.72 The application in olefin epoxidation reaction is characterized by: The dual-phase tungsten oxide WO3•H2O / WO 2.72 Used for the epoxidation of cyclooctene, cyclohexene, 1-hexene, 1-octene, 1-decene, and 1-dodecene.
7. The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO according to claim 5 or 6 2.72 The application in olefin epoxidation reaction is characterized by: The dual-phase tungsten oxide WO3•H2O / WO 2.72 The epoxidation reaction of cyclooctene specifically includes the following steps: 10 ml of acetonitrile is added to a 15 mL reactor, and then 30 mg of dual-phase tungsten oxide WO3•H2O / WO 2.72 , 4 mmol of cyclooctene and 4 mmol of 30% H2O2 were added, After ultrasonic dispersion for 2 minutes, the mixture was sealed and reacted in a water bath at 60°C and 400 r / min for 6 hours. After natural cooling, internal standard anisole was added and quantified by gas chromatography. The conversion of cyclooctene was greater than 96%, and the selectivity of epoxycyclooctane was greater than 99%.
8. The oxygen vacancy-rich dual-phase tungsten oxide WO3•H2O / WO according to claim 5 or 6 2.72 The application in olefin epoxidation reaction is characterized by: The dual-phase tungsten oxide WO3•H2O / WO 2.72 The epoxidation reaction of chemically inactive 1-octene specifically includes the following steps: 10 ml of acetonitrile is added to a 15 mL reactor, and then 30 mg of dual-phase tungsten oxide WO3•H2O / WO 2.72 , 4 mmol of 1-octene and 4 mmol of 30% H2O2 were added, After ultrasonic dispersion for 2 minutes, the mixture was sealed and fixed on a homogeneous reactor. The reaction was carried out at 60°C and 25 r / min for 4 hours. After natural cooling, internal standard anisole was added and quantified by gas chromatography. The conversion of 1-octene was greater than 52%, and the selectivity of 1,2-epoxycyclooctane was greater than 61%.