A dumbbell-shaped Janus solid base catalyst, and a preparation method and application thereof
By preparing dumbbell-shaped Janus solid base catalysts, the problems of difficult separation and high energy consumption of homogeneous catalysts were solved, and efficient biodiesel production was achieved, which has good stability and environmental friendliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2024-03-27
- Publication Date
- 2026-06-05
AI Technical Summary
Existing homogeneous catalysts are difficult to separate and have high energy consumption, while traditional solid base catalysts have weak stability and are difficult to use efficiently in biodiesel production.
Dumbbell-shaped Janus solid base catalysts were prepared by emulsion polymerization. By loading organic bases onto dumbbell-shaped particles to form a core-shell structure, the catalysts achieved amphiphilicity and stability, making them suitable for static transesterification reactions.
This achieves efficient separation and recycling of catalysts, reduces energy consumption, increases biodiesel yield, and aligns with the concept of green environmental protection.
Smart Images
Figure CN118237079B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials, specifically to a dumbbell-shaped Janus solid base catalyst, its preparation method, and its application in the preparation of biodiesel. Background Technology
[0002] As is well known, the definition of organic bases is very broad. Generally, organic bases contain nitrogen atoms, such as amine compounds and nitrogen-containing heterocyclic compounds. From the perspective of the broad acid-base theory, alkali metal salts of alcohols, such as sodium methoxide and potassium ethoxide, and alkyl metal lithium compounds, such as phenyllithium, are all considered organic bases.
[0003] As research into organic bases deepens, their applications have become increasingly widespread, including the preparation of isotope-labeled compounds, ester depolymerization, and transesterification reactions. CN111468184A discloses a supported catalyst, its preparation method, and its applications. The preparation method includes a two-dimensional inorganic clay nanomaterial matrix and an organic base catalyst supported on the matrix. The catalyst synthesizes stable isotope-labeled compounds by reacting stable isotope-labeled CO2 gas with related compounds to prepare carbon-stable isotope-labeled compounds. The resulting compounds have catalysts that are not easily detached and can be reused. CN114797971B authorizes an organic base catalyst and a method for catalyzing the alcoholysis of polycaprolactone. The preparation method involves using an organic base as a catalyst in the polycaprolactone degradation system, which can achieve efficient depolymerization of polycaprolactone under relatively mild conditions to obtain methyl 6-hydroxyhexanoate, a small molecule product with high added value, thus realizing the recycling of waste poly(ε-caprolactone). CN112300378B authorizes an organic base catalyst and a method for its preparation, and a method for preparing polyether polyols using this catalyst. The method uses the organic base catalyst 1,3-bis(dialkylamino)-2-azapropane to prepare polyether polyols. The obtained product has low oligomer content and no metal ion residue. At the same time, in the process of preparing polyether amines using polyether polyols as raw materials, the catalyst has the advantages of long service life and good stability. In addition to homogeneous organic bases, CN116196912B authorizes a calcium-based solid base catalyst. This calcium-based solid base has a porous structure, enhanced acid resistance, and can fully contact oily reactants, providing sufficient basic active sites for the catalytic reaction. Applied to biodiesel production, it achieves a yield of 96% and can be recycled multiple times. CN103657717B authorizes a solid base catalyst for transesterification to diethyl carbonate, achieved by grafting a metal-organic base onto a support. This catalyst exhibits ideal catalytic performance, mild reaction conditions, and low operating costs.
[0004] This demonstrates the wide range of applications for organic base catalysts. While homogeneous catalysts provide an excellent reaction platform and yield high product yields, they often present separation challenges, increasing separation costs to some extent. Although conventional solid base catalysts solve the separation problem, their ability to stabilize the system is weak, requiring continuous energy input to maintain the reaction and increasing energy consumption.
[0005] Therefore, it is necessary to prepare a solid organic base catalyst with high efficiency, separation mechanism and good stability. Summary of the Invention
[0006] This invention provides a dumbbell-shaped Janus solid base catalyst, its preparation method, and its application in static catalytic transesterification to produce biodiesel.
[0007] The technical solution of the present invention is as follows:
[0008] In a first aspect, the present invention provides a method for preparing a dumbbell-shaped Janus solid base catalyst, comprising the following steps:
[0009] (1) Polystyrene latex containing polystyrene particles was prepared by emulsion polymerization; the average particle size of the polystyrene latex obtained in this step was between 100 nm and 135 nm.
[0010] (2) Using the polystyrene latex obtained in step (1), p-chloromethylstyrene, and divinylbenzene as reactants, the polystyrene particles with a core-shell structure are polymerized on the surface of the polystyrene particles by seed emulsion polymerization. The average particle size of the chlorinated polystyrene particles obtained in this step is between 130 nm and 165 nm.
[0011] (3) Preparation of dumbbell-shaped Janus particles
[0012] The chlorinated polystyrene, styrene, divinylbenzene and sodium dodecyl sulfate obtained in step (2) were dispersed in water and swollen at room temperature for 48-52 h. Then the system was heated to 78-82 °C and kept at that temperature for 2-2.5 h. After the system cooled to room temperature, hydroquinone aqueous solution and azobisisobutyronitrile styrene solution were added. Finally, the reaction was stirred at 78-82 °C for 8-10 h. The solid product was then centrifuged, washed (preferably with ethanol and deionized water in sequence), and freeze-dried to obtain dumbbell-shaped Janus particles.
[0013] The mass ratio of chlorinated polystyrene, styrene, divinylbenzene, sodium dodecyl sulfate, hydroquinone, and azobisisobutyronitrile is 1:5~7:0.35~0.45:0.5~0.7:0.003~0.004:0.03~0.04;
[0014] The mass ratio of chlorinated polystyrene to water is 1:35-40;
[0015] The concentration of hydroquinone aqueous solution is 5 mmol / L to 20 mmol / L, preferably 10 mmol / L to 20 mmol / L;
[0016] The mass ratio of azobisisobutyronitrile to solvent styrene in the styrene solution of the azobisisobutyronitrile is 1:43-45.
[0017] The dumbbell-shaped Janus particles obtained in this step have an average particle size between 245 nm and 320 nm.
[0018] (4) Preparation of dumbbell-shaped Janus solid base catalyst
[0019] The dumbbell-shaped Janus particles obtained in step (3) were ultrasonically dispersed in 1,4-dioxane, and organic base, tetrabutylammonium iodide and sodium hydroxide were added. The mixture was magnetically stirred at 58-62°C for 24-26 hours. After the mixture was finished, it was centrifuged and washed until neutral (preferably with ethanol). It was then freeze-dried to obtain dumbbell-shaped Janus solid base catalyst.
[0020] The mass ratio of dumbbell-shaped Janus particles, 1,4-dioxane, tetrabutylammonium iodide, and sodium hydroxide is 1:30-65:0.25-0.30:0.9-1.1.
[0021] The molar ratio of organic base to sodium hydroxide is 1:3.5 to 4.0;
[0022] The organic base is selected from trimethylamine, 1,1,4,4-tetramethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene or 1,8-diazabicyclo[5.4.0]undec-7-ene;
[0023] The dumbbell-shaped Janus solid base catalyst obtained in this step has an average particle size between 246 nm and 325 nm.
[0024] Preferably, the polystyrene latex is prepared by the following method:
[0025] Styrene, divinylbenzene, and sodium dodecyl sulfate were ultrasonically dispersed in deionized water. After purging with nitrogen to remove oxygen, the mixture was heated to 78–82°C. A potassium persulfate aqueous solution with a concentration of 0.0095 g / mL–0.0105 g / mL was added dropwise. After reacting for 8–12 hours, polystyrene latex was obtained. The mass ratio of styrene, divinylbenzene, sodium dodecyl sulfate, and potassium persulfate was 1:0.030–0.035:0.01–0.02:0.015–0.020, and the mass ratio of styrene to deionized water was 1:12–13.
[0026] Preferably, the chlorinated polystyrene is prepared by the following method:
[0027] Sodium dodecyl sulfate aqueous solution, polystyrene latex obtained in step (1), p-chloromethylstyrene and divinylbenzene were mixed, and nitrogen gas was passed through the mixture under stirring to remove oxygen. The mixture was then heated to 58-62°C. An aqueous solution of potassium persulfate and sodium bisulfite was added dropwise, and the reaction was continued for 4-12 hours. After that, the reaction mixture was centrifuged, washed with deionized water, and freeze-dried to obtain chlorinated polystyrene.
[0028] The mass ratio of polystyrene latex, p-chloromethylstyrene, divinylbenzene, sodium dodecyl sulfate, potassium persulfate, and sodium bisulfite is 1:0.09-0.15:0.0020-0.0035:0.0005-0.0010:0.0047-0.0065:0.0035-0.0050; the mass ratio of sodium dodecyl sulfate to deionized water in the sodium dodecyl sulfate aqueous solution is 1:35-45.
[0029] In the aqueous solution of potassium persulfate and sodium bisulfite, the mass ratio of potassium persulfate to solvent water is 1:50 to 150, preferably 1:50 to 100.
[0030] In a second aspect, the present invention provides a dumbbell-shaped Janus solid base catalyst prepared according to the preparation method described in the first aspect.
[0031] Thirdly, the present invention provides the application of the dumbbell-shaped Janus solid base catalyst in the static catalytic transesterification process for biodiesel production.
[0032] The static catalytic transesterification refers to the production of biodiesel through static transesterification of oils and alcohols. The oils can be vegetable oils (such as rapeseed oil, soybean oil, peanut oil, corn oil, cottonseed oil, etc.), animal oils (such as fish oil, lard, tallow, mutton tallow, etc.), or microbial oils. The alcohol is methanol or ethanol. Static transesterification means that the transesterification process is a static reaction process, without the need for high-speed stirring, ultrasound, or other equipment to enhance mass transfer.
[0033] In a specific embodiment of the present invention, the application is as follows: dumbbell-shaped Janus solid base catalyst is ultrasonically dispersed in alcohol, oil is added, and the mixture is sheared at high speed using a high-speed homogenizer to form an emulsion. The emulsion is then statically reacted in an oil bath at 50–70°C for 10–15 hours. The emulsion is centrifuged to break the emulsion, and the oil phase is dried in an oven to remove methanol, yielding biodiesel. The recovered catalyst is washed and dried with methanol for recycling.
[0034] This invention first prepares polystyrene latex via emulsion polymerization. Then, using seeded emulsion polymerization, it polymerizes chlorinated polystyrene particles with a core-shell structure on the surface of polystyrene microspheres. Next, using these chlorinated polystyrene particles as seeds, it swells to obtain Janus particles with chlorinated polystyrene at one end and pure polystyrene at the other. Finally, amination yields a dumbbell-shaped Janus solid base catalyst with a single-sided organic base supported. Compared with existing technologies, the advantages of this invention are:
[0035] 1. The dumbbell-shaped Janus solid base catalyst of the present invention loads organic base onto dumbbell-shaped solid particles, making the solid particles exhibit the characteristics of organic base. During use, it is insoluble in any phase, and after use, the catalyst can be separated simply by centrifugation. This perfectly solves the problem of difficult separation and recovery of homogeneous catalysts, reduces catalyst waste and separation energy consumption to a certain extent, lowers the risk of environmental pollution, and conforms to the concept of green and environmentally friendly development.
[0036] 2. The dumbbell-shaped Janus solid base catalyst of the present invention has a difference in hydrophilicity and hydrophobicity at both ends due to the immobilization of organic base on one side, and the particles are amphiphilic, which has a great advantage in stabilizing two-phase systems.
[0037] 3. When the catalyst of the present invention is applied to transesterification to prepare biodiesel, the biodiesel yield can reach more than 85%. Due to its good wettability and amphiphilicity, it does not require long-term energy input, thus reducing energy consumption. Attached Figure Description
[0038] Figure 1 The image shows a transmission electron microscopy (TEM) image of the dumbbell-shaped Janus solid base catalyst DB-JPP-TMA prepared in Example 1 of this invention.
[0039] Figure 2 Transmission microscopy image of the dumbbell-shaped Janus solid base catalyst DB-JPP-TMG prepared in Example 2 of this invention;
[0040] Figure 3 Transmission microscopy image of the dumbbell-shaped Janus solid base catalyst DB-JPP-TBD prepared in Example 3 of this invention;
[0041] Figure 4 Transmission microscopy image of the dumbbell-shaped Janus solid base catalyst DB-JPP-DBU prepared in Example 4 of this invention;
[0042] Figure 5 Transmission microscopy image of dumbbell-shaped Janus particles DB-JPP prepared in Comparative Example 1 of this invention;
[0043] Figure 6 Fourier transform infrared spectra of dumbbell-shaped Janus solid base catalysts DB-JPP-OBC (TMA, TMG, TBD, DBU) prepared in Examples 1-4 of this invention and dumbbell-shaped Janus solid particles DB-JPP prepared in Comparative Example 1.
[0044] Figure 7 The static water contact angles of the dumbbell-shaped Janus solid base catalyst DB-JPP-OBC (TMA, TMG, TBD, DBU) prepared in Examples 1-4 of this invention and the dumbbell-shaped Janus solid particles DB-JPP prepared in Comparative Example 1 are shown.
[0045] Figure 8 TEM image of dumbbell-shaped palladium-loaded Janus polymer particles (DB-JPP-Pd) prepared in Example 1 of this invention;
[0046] Figure 9 These are DLS images of the seven types of particles prepared in the examples;
[0047] Figure 10 This is a schematic diagram of a typical preparation process for the dumbbell-shaped Janus solid base catalyst prepared in this invention. Detailed Implementation
[0048] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0049] Example 1
[0050] (1) Preparation of polystyrene latex
[0051] 10.2 g styrene, 0.34 g divinylbenzene, and 0.13 g sodium dodecyl sulfate were ultrasonically dispersed in 130 mL deionized water. After purging with nitrogen for 30–45 min to remove oxygen, the mixture was heated to 80 °C, and potassium persulfate aqueous solution (0.2 g / 20 mL) was added dropwise. After reacting for 12 h, a 7.4 wt% polystyrene latex was obtained. The DLS diagram of the particles is shown in [Figure number missing]. Figure 9 .
[0052] (2) Preparation of chlorinated polystyrene
[0053] 0.1 g of sodium dodecyl sulfate was ultrasonically dispersed in 40 mL of water. 100 mL of the polystyrene latex obtained in step (1), 16 g of p-chloromethylstyrene, and 0.36 g of divinylbenzene were added. The mechanical stirring speed was set to 300 r / min. After purging with N2 for 60 min to remove oxygen, the temperature was raised to 60 °C. An aqueous solution of potassium persulfate and sodium bisulfite (0.68 g / 0.51 g / 40 mL) was added dropwise, and the reaction continued for 4 h. The product was then centrifuged, washed with deionized water, and freeze-dried to obtain chlorinated polystyrene particles. The DLS diagram is shown below. Figure 9 .
[0054] (3) Preparation of dumbbell-shaped Janus particles
[0055] 5 g of chlorinated polystyrene particles and 3.2 g of sodium dodecyl sulfate were ultrasonically dispersed in 195 mL of water. 30 g of styrene and 1.8 g of divinylbenzene were added, and the mixture swelled at room temperature for 48 h. The system was then heated to 80 °C and held at that temperature for 2 h. After cooling to room temperature, hydroquinone aqueous solution (16 mM, 10 mL) and a styrene solution of azobisisobutyronitrile (0.165 g / 7.25 g) were added. Finally, the mixture was stirred at 80 °C for 10 h. The solid product was then centrifuged, washed sequentially with ethanol and deionized water, and freeze-dried to obtain dumbbell-shaped Janus particles (DB-JPP). Their DLS diagram is shown below. Figure 9 .
[0056] (4) Preparation of dumbbell-shaped Janus solid base catalyst
[0057] 1 g of the dumbbell-shaped Janus particles obtained above were ultrasonically dispersed in 60 mL of 1,4-dioxane. 0.41 g of trimethylamine, 0.25 g of tetrabutylammonium iodide, and 1 g of sodium hydroxide were added. The mixture was magnetically stirred at 60 °C for 24 h. After stirring, the mixture was centrifuged and washed with ethanol until neutral. The mixture was then freeze-dried to obtain the dumbbell-shaped Janus solid base catalyst DB-JPP-TMA. Its DLS diagram is shown below. Figure 9 .
[0058] Transmission electron microscopy images of the particles are shown below. Figure 1 The particle size is approximately 287 nm. Infrared spectra are shown below. Figure 6 .Depend on Figure 6 The spectrum shows that at 1648cm -1 A CN peak appears at 1263 cm⁻¹. -1 The disappearance of the chloromethyl peak indicates successful grafting of the amino group. The static water contact angle is shown below. Figure 7 ,Depend on Figure 7 It can be seen that the static water contact angle of the dumbbell-shaped Janus solid base catalyst DB-JPP-TMA is 98°.
[0059] (5) Verify the one-sided grafting of TMA in DB-JPP-TMA
[0060] 0.6 g of DB-JPP-TMA was ultrasonically dispersed in an ethanol-water solution (25 wt%, 80 mL). H₂PdCl₄ aqueous solution (5 mM, 10 mL) was added dropwise to the suspension, and the mixture was stirred at room temperature for 3 h. The solid precipitate was obtained by centrifugation and washed three times with anhydrous ethanol. The product was then ultrasonically dispersed in an ethanol-water solution (25 wt%, 80 mL), and NaBH₄ aqueous solution (0.1 M, 25 mL) was added. The mixture was stirred at room temperature for 6 h. Dumbbell-shaped palladium-loaded Janus polymer particles (DB-JPP-Pd) were obtained by centrifugation, washing, and freeze-drying. DB-JPP-Pd was then imaged using TEM. Figure 8 As can be seen, Pd is fixed on only one side, which indirectly illustrates the unilateral grafting of organic base TMA.
[0061] Example 2
[0062] Repeat Example 1, except that in step (4) of Example 1, 0.41g of trimethylamine is replaced with 0.81g of 1,1,4,4-tetramethylguanidine.
[0063] The remaining steps are the same as in Example 1, and the dumbbell-shaped Janus solid base catalyst DB-JPP-TMG is finally obtained. Its DLS diagram is shown in [Figure 1]. Figure 9 .
[0064] Transmission electron microscopy images of the particles are shown below. Figure 2 The particle size is approximately 292 nm. Infrared spectra are shown below. Figure 6 .Depend on Figure 6 The spectrum shows that at 1648cm -1 A CN peak appears at 1263 cm⁻¹. -1 The disappearance of the chloromethyl peak indicates successful grafting of the guanidine group. The static water contact angle is shown below. Figure 7 ,Depend on Figure 7 It can be seen that the static water contact angle of the dumbbell-shaped Janus solid base catalyst DB-JPP-TMG is 92°.
[0065] Example 3
[0066] Repeat Example 1, except that in step (4) of Example 1, 0.41 g of trimethylamine is replaced with 0.97 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene.
[0067] The remaining steps are the same as in Example 1, and the dumbbell-shaped Janus solid base catalyst DB-JPP-TBD is finally obtained. Its DLS diagram is shown in [Figure 1]. Figure 9 .
[0068] Transmission electron microscopy images of the particles are shown below. Figure 3 The particle size is approximately 295 nm. Infrared spectra are shown below. Figure 6 .Depend on Figure 6 The spectrum shows that at 1648cm -1 A CN peak appears at 1263 cm⁻¹. -1 The disappearance of the chloromethyl peak indicates successful grafting of the cyclic guanidine group. The static water contact angle is shown below. Figure 7 ,Depend on Figure 7 It can be seen that the static water contact angle of the dumbbell-shaped Janus solid base catalyst DB-JPP-TBD is 88°.
[0069] Example 4
[0070] Repeat Example 1, except that in step (4) of Example 1, 0.41 g of trimethylamine is replaced with 1.07 g of 1,8-diazabicyclo[5.4.0]undec-7-ene.
[0071] The remaining steps are the same as in Example 1, and the dumbbell-shaped Janus solid base catalyst DB-JPP-DBU is finally obtained. Its DLS diagram is shown in [Figure 1]. Figure 9 .
[0072] Transmission electron microscopy images of the particles are shown below. Figure 4 The particle size is approximately 297 nm. Infrared spectra are shown below. Figure 6 .Depend on Figure 6 The spectrum shows that at 1648cm -1 A CN peak appears at 1263 cm⁻¹. -1 The disappearance of the chloromethyl peak indicates successful grafting of the amidine group. The static water contact angle is shown below. Figure 7 ,Depend on Figure 7 It can be seen that the static water contact angle of the dumbbell-shaped Janus solid base catalyst DB-JPP-DBU is 86°.
[0073] Comparative Example 1
[0074] Repeat Example 1, except that after step (3) in Example 1, the organic base loading treatment in step (4) is no longer performed, and dumbbell-shaped Janus particles DB-JPP are obtained.
[0075] Transmission electron microscopy images of the obtained particles are shown below. Figure 5 The particle size is approximately 285 nm. Infrared spectra are shown below. Figure 6 .Depend on Figure 6 The spectrum shows that at 1263 cm⁻¹ -1 The presence of a chloromethyl peak indicates the presence of chloromethyl groups. The static water contact angle is shown below. Figure 7 ,Depend on Figure 7 It can be seen that the static water contact angle of dumbbell-shaped Janus solid particles DB-JPP is 106°.
[0076] Application Examples 1-4
[0077] Four dumbbell-shaped Janus solid base catalysts prepared in Examples 1-4 were used for static transesterification to produce biodiesel: 0.69 g of dumbbell-shaped Janus solid base catalyst (5.5 wt% oil phase) was ultrasonically dispersed in 7.00 g of methanol, and 12.5 g of soybean oil was added. The mixture was then subjected to high-speed shearing using a high-speed homogenizer to form an emulsion, which was then reacted in a 60°C oil bath for 12 h. The emulsion was centrifuged to break the emulsion, and the oil phase was dried in an oven to remove methanol. The biodiesel yield was calculated using gas chromatography. The recovered catalyst was washed and dried with methanol for recycling. The methanol-to-oil molar ratio was 15:1.
[0078] As shown in Table 1, among the four dumbbell-shaped Janus solid base catalysts, the DB-JPP-TBD catalyst supported on 1,5,7-triazabicyclo[4.4.0]dec-5-ene exhibits the best catalytic performance.
[0079] Table 1. Effect of organic base groups in the catalyst on catalyst activity.
[0080]
[0081] Application Example 5
[0082] The catalyst from Example 3 was used for static transesterification to prepare biodiesel: 0.6875 g of dumbbell-shaped Janus solid base catalyst (5.5 wt% oil phase) was ultrasonically dispersed in 7.00 g of methanol. 12.5 g of soybean oil was added, and the mixture was homogenized using a high-speed homogenizer to form an emulsion. The emulsion was then reacted in a 60°C oil bath for 12 h. The emulsion was centrifuged to break the emulsion, and the oil phase was dried in an oven to remove methanol. The biodiesel yield was calculated using gas chromatography. After the reaction, the solid catalyst was recovered through centrifugation, washing, and drying for reuse. The catalyst activity after multiple cycles was compared.
[0083] Table 2 Effect of catalyst cycle number on catalyst activity
[0084]
[0085] As shown in Table 2, after 5 cycles, the catalyst activity was 97% of the initial activity. The prepared solid base catalyst exhibits high catalytic activity and good cycle stability.
[0086] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.
Claims
1. A method for preparing a dumbbell-shaped Janus solid base catalyst, characterized in that: The preparation method includes the following steps: (1) Polystyrene latex containing polystyrene particles was prepared by emulsion polymerization; the average particle size of the polystyrene particles in the polystyrene latex obtained in this step was between 100 nm and 135 nm. (2) Using the polystyrene latex obtained in step (1), p-chloromethylstyrene, and divinylbenzene as reactants, chlorinated polystyrene particles with a core-shell structure are generated on the surface of polystyrene particles by seed emulsion polymerization. The average particle size of the chlorinated polystyrene microspheres obtained in this step is between 130 nm and 165 nm. (3) Preparation of dumbbell-shaped Janus particles The chlorinated polystyrene, styrene, divinylbenzene and sodium dodecyl sulfate obtained in step (2) were dispersed in water and swollen at room temperature for 48-52 h. Then the system was heated to 78-82 °C and kept at that temperature for 2-2.5 h. After the system cooled to room temperature, hydroquinone aqueous solution and azobisisobutyronitrile styrene solution were added. Finally, the reaction was stirred at 78-82 °C for 8-10 h. The solid product was then centrifuged, washed and freeze-dried to obtain dumbbell-shaped Janus particles. The mass ratio of chlorinated polystyrene, styrene, divinylbenzene, sodium dodecyl sulfate, hydroquinone, and azobisisobutyronitrile is 1:5~7:0.35~0.45:0.5~0.7:0.003~0.004:0.03~0.04; The mass ratio of chlorinated polystyrene to water is 1:35-40; Hydroquinone aqueous solution concentration is 5 mmol / L to 20 mmol / L; The mass ratio of azobisisobutyronitrile to solvent styrene in the styrene solution of the azobisisobutyronitrile is 1:43-45. The dumbbell-shaped Janus particles obtained in this step have an average particle size between 245 nm and 320 nm. (4) Preparation of dumbbell-shaped Janus solid base catalyst The dumbbell-shaped Janus particles obtained in step (3) were ultrasonically dispersed in 1,4-dioxane, and organic base, tetrabutylammonium iodide and sodium hydroxide were added. The mixture was magnetically stirred at 58-62℃ for 24-26 hours. After the mixture was finished, it was centrifuged and washed until neutral, and then freeze-dried to obtain dumbbell-shaped Janus solid base catalyst. The mass ratio of dumbbell-shaped Janus particles, 1,4-dioxane, tetrabutylammonium iodide, and sodium hydroxide is 1:30-65:0.25-0.30:0.9-1.
1. The molar ratio of organic base to sodium hydroxide is 1:3.5 to 4.0; The organic base is selected from trimethylamine, 1,1,4,4-tetramethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene or 1,8-diazabicyclo[5.4.0]undec-7-ene; The dumbbell-shaped Janus solid base catalyst obtained in this step has an average particle size between 246 nm and 325 nm.
2. The preparation method according to claim 1, characterized in that: The polystyrene latex is prepared by the following method: Styrene, divinylbenzene, and sodium dodecyl sulfate were ultrasonically dispersed in deionized water. After purging with nitrogen to remove oxygen, the mixture was heated to 78–82°C. A potassium persulfate aqueous solution with a concentration of 0.0095 g / mL–0.0105 g / mL was added dropwise. After reacting for 8–12 hours, polystyrene latex was obtained. The mass ratio of styrene, divinylbenzene, sodium dodecyl sulfate, and potassium persulfate was 1:0.030–0.035:0.01–0.02:0.015–0.020, and the mass ratio of styrene to deionized water was 1:12–13.
3. The preparation method according to claim 1, characterized in that: The chlorinated polystyrene is prepared by the following method: Sodium dodecyl sulfate aqueous solution, polystyrene latex obtained in step (1), p-chloromethylstyrene and divinylbenzene were mixed, and nitrogen gas was passed through the mixture under stirring to remove oxygen. The mixture was then heated to 58-62°C. An aqueous solution of potassium persulfate and sodium bisulfite was added dropwise, and the reaction was continued for 4-12 hours. After that, the reaction mixture was centrifuged, washed with deionized water, and freeze-dried to obtain chlorinated polystyrene. The mass ratio of polystyrene latex, p-chloromethylstyrene, divinylbenzene, sodium dodecyl sulfate, potassium persulfate, and sodium bisulfite is 1:0.09-0.15:0.0020-0.0035:0.0005-0.0010:0.0047-0.0065:0.0035-0.0050; the mass ratio of sodium dodecyl sulfate to deionized water in the sodium dodecyl sulfate aqueous solution is 1:35-45. In the aqueous solution of potassium persulfate and sodium bisulfite, the mass ratio of potassium persulfate to solvent water is 1:50 to 150.
4. The preparation method according to claim 1, characterized in that: In step (3), the concentration of hydroquinone aqueous solution is 10 mmol / L to 20 mmol / L.
5. A dumbbell-shaped Janus solid base catalyst prepared by the preparation method according to any one of claims 1-4.
6. The application of the dumbbell-shaped Janus solid base catalyst as described in claim 5 in the static catalytic transesterification process for biodiesel production.
7. The application as described in claim 6, characterized in that: The static catalytic transesterification refers to the generation of biodiesel from oils and alcohols through static transesterification; the oils are vegetable oils, animal oils, or microbial oils; and the alcohols are methanol or ethanol.
8. The application as described in claim 7, characterized in that: The specific application is as follows: dumbbell-shaped Janus solid base catalyst is ultrasonically dispersed in alcohol, oil is added to it, the mixture is sheared at high speed using a high-speed homogenizer to form an emulsion, and then placed in an oil bath at 50-70°C for static reaction for 10-15 hours. The emulsion is centrifuged to break the emulsion, and the oil phase is dried in an oven to remove methanol, thus obtaining biodiesel.