Amphiphilic ester exchange catalyst as well as preparation method and application thereof
By designing a heterogeneous solid base catalyst with amphiphilic properties, and utilizing hydrophobic carbon materials and hydrophilic strong base weak acid salts to form a stable Pickering emulsion, the problems of slow reaction rate and high temperature were solved, enabling rapid, efficient, and environmentally friendly production of biodiesel.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-03
- Publication Date
- 2026-04-03
Smart Images
Figure CN121775876A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, specifically to an amphiphilic transesterification catalyst, its preparation method, and its application. Background Technology
[0002] Biodiesel is a fatty acid ester prepared from oils and small-molecule alcohols via transesterification. It exhibits combustion characteristics similar to petroleum diesel and is a renewable, biodegradable, and clean energy source that can replace fossil fuels. However, current industrial production of biodiesel faces numerous challenges, such as stringent requirements on the moisture and free fatty acid content of the feedstock, difficulties in product separation, and the generation of acidic and alkaline wastewater causing secondary environmental pollution. These issues hinder large-scale industrial production of biodiesel, and the root cause lies in the use of homogeneous base catalysts in its synthesis process. To address these problems, researchers are currently conducting extensive studies on using heterogeneous solid bases to replace traditional homogeneous solid bases in the preparation of biodiesel.
[0003] Heterogeneous solid bases are reusable and produce less acid and alkali waste liquid during the reaction process, making them a promising alternative to traditional homogeneous base catalysis for transesterification reactions. Currently, numerous solid bases have been studied for use in transesterification reactions. Alkaline earth metal oxides, strong base-weak acid salts, and supported catalysts with these bases as active centers all exhibit good catalytic activity. However, research also shows that slow reaction rates and high reaction temperatures remain key constraints on their industrial application. The primary reason for the slow reaction rate and high reaction temperature in transesterification reactions catalyzed by heterogeneous solid bases is that the addition of solid bases transforms the alcohol-oil liquid-liquid heterogeneous system into a liquid-liquid-solid ternary heterogeneous system. This not only reduces the effective contact area between the alcohol, oil, and catalyst but also prolongs the diffusion distance of active intermediates. Therefore, effectively improving the mixing homogeneity of the liquid-liquid-solid ternary heterogeneous system has become crucial for its industrial application.
[0004] Traditional methods such as mechanical stirring, ultrasound, adding co-soluble solvents, and utilizing supercritical fluids all have some effect on mixing liquid-liquid heterogeneous systems, but their effectiveness remains relatively limited when dealing with liquid-liquid-solid three-phase heterogeneous systems. In fact, amphiphilic solid particles can promote the formation of emulsions in liquid-liquid heterogeneous systems, commonly known as Pickering emulsions. In this emulsion, one liquid phase is uniformly dispersed in the other liquid phase as droplets, while the amphiphilic solid particles remain stably present at the phase interface between the two liquid phases. Given the properties of Pickering emulsions, if amphiphilic heterogeneous solid alkali particles can be designed and developed, it would not only effectively increase the alcohol-oil contact area but also shorten the diffusion distance of active intermediates, thus contributing to the rapid and efficient preparation of biodiesel. Based on this concept, our research group developed a heterogeneous solid base catalyst with high catalytic performance, using hydrophobic carbon materials as a support and hydrophilic strong base-weak acid salts as the active center. This catalyst not only enables the transesterification reaction of frying waste oil with methanol at room temperature, but also achieves a rapid reaction rate, with a biodiesel conversion rate of 90% in just 30 minutes. Furthermore, this catalyst exhibits excellent resistance to free fatty acids and water, making it a promising high-efficiency heterogeneous solid base catalyst for industrial application. Summary of the Invention
[0005] This invention addresses the problems of slow reaction rate and high reaction temperature in existing heterogeneous solid base catalytic transesterification reactions. By analogy with the structural characteristics of Pickering emulsion, a heterogeneous solid base catalyst with amphiphilic properties is developed.
[0006] The technical solution of this invention is implemented as follows: This invention provides an amphiphilic transesterification catalyst, which is composed of the following raw materials in parts by weight: 100-120 parts carbon powder, 10-40 parts active center, 70-100 parts dispersant, and an appropriate amount of modifier.
[0007] As a further improvement of the present invention, the carbon powder is one or more of coal-based activated carbon, coconut shell activated carbon, and wood-based activated carbon.
[0008] As a further improvement of the present invention, the active center is one or more of sodium fluoride, potassium fluoride, potassium acetate, sodium acetate, potassium phosphate, sodium phosphate, potassium carbonate, sodium carbonate, sodium formate, and potassium formate.
[0009] As a further improvement of the present invention, the dispersant is one or more of ethanol, methanol, propanol, tert-butanol, diethyl ether, ethyl acetate, benzene and deionized water.
[0010] As a further improvement of the present invention, the modifier is one or more of ethylene, acetylene, methane, ethane, and propane, or a combination thereof.
[0011] This invention further protects a method for preparing the above-mentioned amphiphilic transesterification catalyst, comprising the following steps: (1) Carbon powder pretreatment: Accurately weigh the carbon powder, calcine it under inert gas protection, and then cool it; (2) Active center loading: Accurately weigh the active center, add dispersant to dissolve it, add pretreated carbon powder, stir and mix, dry to obtain catalyst precursor; (3) Preparation of amphiphilic transesterification catalyst: The catalyst precursor was heated and calcined under inert gas protection, modified by introducing a modifier, and then switched to inert gas, cooled to room temperature, and ball-milled to obtain an amphiphilic transesterification catalyst.
[0012] As a further improvement of the present invention, the roasting temperature in step (1) is 500-900℃ and the time is 1-3h.
[0013] As a further improvement of the present invention, the stirring and mixing time in step (2) is 3-5 hours.
[0014] As a further improvement of the present invention, the heating and calcination in step (3) is to raise the temperature to 400-700℃ at 10℃ / min, the flow rate of the modifier in the modification is 200-500mL / min, the modification time is 3-5h, and the ball milling is 1-2h.
[0015] This invention further protects the application of the above-mentioned amphiphilic transesterification catalyst in transesterification reaction catalysis.
[0016] The present invention has the following beneficial effects: (1) The preparation process is simple and easy to operate. The preparation process does not use strong acids or strong alkalis, so it will not cause strong corrosion to the equipment, nor will it generate a large amount of acid and alkali wastewater, which is beneficial to environmental protection.
[0017] (2) From the perspective of the entire formula, all reagents and materials are conventional commercially available reagents and materials, which are conducive to industrial production and application.
[0018] (3) The active center of the obtained catalyst is a strong base weak acid salt, which is not affected by moisture and CO2 in the air and can maintain catalytic activity during long-term storage.
[0019] (4) The amphiphilic transesterification catalyst prepared by the present invention can form a stable emulsion in the heterogeneous system of oil and alcohol, effectively increasing the contact area between alcohol, oil and catalyst, and greatly improving the conversion rate and reaction rate of oil transesterification.
[0020] (5) The solid base catalyst obtained by the present invention not only enables the transesterification reaction to be carried out at room temperature, but also exhibits excellent reusability and resistance to free fatty acids and water. Studies have shown that even after being repeated 4 times, the transesterification conversion rate of frying waste oil still exceeds 85%. In addition, even with a water content of <1.1% and a free fatty acid content of <0.4% in the raw oil, the conversion rate of biodiesel can still exceed 90%. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a process flow diagram for the preparation of amphiphilic transesterification catalysts; Figure 2 SEM image of the amphiphilic transesterification catalyst; Figure 3 The diagram shows the emulsification effect of an amphiphilic transesterification catalyst on an alcohol-oil system. Detailed Implementation
[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1
[0024] like Figure 1 As shown, the amphiphilic transesterification catalyst of the present invention is composed of the following components by weight: 100 parts of coal-based powdered activated carbon, 15 parts of active center KF, 75 parts of dispersant, and ethylene modifier. The dispersant is a mixture of water and methanol in a volume ratio of 1:5.
[0025] The preparation method of the amphiphilic transesterification catalyst of the present invention includes the following steps: (1) Carbon powder pretreatment: Accurately weigh 100 parts of coal-based powdered activated carbon, place it in a vacuum tube furnace under nitrogen protection, calcine at 900℃ for 1 hour, and then cool naturally to room temperature.
[0026] (2) Active center loading: Accurately weigh 15 parts of active center KF, place it in a beaker, add 75 parts of dispersant by mass, and after it dissolves, add pretreated coal-based powdered activated carbon to the dispersant, mix for 3 hours under magnetic stirring, and then put it in an oven and dry it at 50°C to constant weight to obtain the catalyst precursor.
[0027] (3) Preparation of amphiphilic transesterification catalyst: The catalyst precursor was placed in a vacuum tube furnace and heated to 500℃ at 10℃ / min under nitrogen protection. Then, ethylene, a modifier, was introduced at this temperature at a flow rate of 350 mL / min for 5 h. After that, nitrogen was switched back to the furnace, and the temperature was allowed to cool naturally to room temperature. The catalyst was then milled in a planetary ball mill for 1.5 h to obtain an amphiphilic transesterification catalyst, such as... Figure 2 The figure shows the microstructure of the amphiphilic transesterification catalyst. As can be seen from the figure, after loading and modification with modifiers, a large number of whisker-like substances and particles appear on its surface. Among them, the whisker-like substances have hydrophobic effects, while the particles are active centers. The two work together to enable the catalyst to exhibit amphiphilic properties. Figure 3 As shown in the figure, methanol exists as micron-sized droplets in the continuous phase of the oil and fat, and there is a black boundary between them. This boundary is an amphiphilic transesterification catalyst. This distribution of alcohol-oil-catalyst helps the transesterification reaction to proceed rapidly.
[0028] The average particle diameter of the amphiphilic transesterification catalyst was determined to be 50 μm using a laser particle size analyzer, and its basicity was determined to be 10.3 using the Hammett indicator titration method. Using waste frying oil as raw material, at an alcohol-to-oil molar ratio of 10:1, a catalyst dosage of 10% of the oil weight, a reaction temperature of 25℃, and a reaction time of 30 min, the transesterification conversion rate reached 93.1%. The catalyst was washed twice with an equal volume of deionized water, resulting in a wash water pH of 7.10. Reuse experiments showed that even after four repetitions, the transesterification conversion rate still reached 90.2%. Example 2
[0029] like Figure 1 As shown, the amphiphilic transesterification catalyst of the present invention is composed of the following components by weight: 120 parts of coconut shell powder activated carbon, 20 parts of active center Na2CO3, 80 parts of dispersant, and acetylene as modifier. The dispersant is a mixed solution of water and ethanol in a volume ratio of 1:5.
[0030] The preparation method of the amphiphilic transesterification catalyst of the present invention includes the following steps: (1) Carbon powder pretreatment: Accurately weigh 100 parts of coconut shell powder activated carbon, place it in a vacuum tube furnace under nitrogen protection, calcine at 900℃ for 1 hour, and then cool naturally to room temperature.
[0031] (2) Active center loading: Accurately weigh 20 parts of active center Na2CO3, place it in a beaker, add 80 parts of dispersant by mass, and after it dissolves, add pretreated coconut shell powder activated carbon to the dispersant, mix under magnetic stirring for 5 hours, and then put it in an oven and dry it at 70°C to constant weight to obtain the catalyst precursor.
[0032] (3) Preparation of amphiphilic transesterification catalyst: The catalyst precursor was placed in a vacuum tube furnace and heated to 500°C at 10°C / min under nitrogen protection. Then, acetylene was introduced at this temperature at a flow rate of 500 mL / min for 3 hours. Nitrogen was then switched to nitrogen and the temperature was naturally cooled to room temperature. The catalyst was then placed in a planetary ball mill and ground for 2 hours to obtain an amphiphilic transesterification catalyst.
[0033] The average particle diameter of the amphiphilic transesterification catalyst was determined to be 38 μm using a laser particle size analyzer, and its basicity was determined to be 9.7 using the Hammett indicator titration method. Using waste frying oil as raw material, at an alcohol-to-oil molar ratio of 20:1, a catalyst dosage of 8% of the oil weight, a reaction temperature of 65℃, and a reaction time of 10 min, the transesterification conversion rate reached 94.2%. The catalyst was washed twice with an equal volume of deionized water at a pH of 6.92. Reuse experiments showed that even after five repetitions, the transesterification conversion rate still reached 90.7%. Example 3
[0034] like Figure 1 As shown, the amphiphilic transesterification catalyst of the present invention is composed of the following components by weight: 110 parts of wood-based powdered activated carbon, 20 parts of active center K2CO3, 100 parts of dispersant, and acetylene as modifier. The dispersant is a mixed solution of water, propanol, and ethanol in a volume ratio of 2:1:3.
[0035] The preparation method of the amphiphilic transesterification catalyst of the present invention includes the following steps: (1) Carbon powder pretreatment: Accurately weigh 100 parts of wood powder activated carbon, place it in a vacuum tube furnace under nitrogen protection, calcine at 700℃ for 1 hour, and then cool naturally to room temperature.
[0036] (2) Active center loading: Accurately weigh 20 parts of active center K2CO3, place it in a beaker, add 100 parts of dispersant by mass, and after it dissolves, add pretreated wood powder activated carbon to the dispersant, mix under magnetic stirring for 5 hours, and then put it in an oven and dry it at 70°C to constant weight to obtain the catalyst precursor.
[0037] (3) Preparation of amphiphilic transesterification catalyst: The catalyst precursor was placed in a vacuum tube furnace and heated to 500°C at 10°C / min under nitrogen protection. Then, acetylene was introduced at this temperature at a flow rate of 400 mL / min for 5 hours. Nitrogen was then introduced and the temperature was naturally cooled to room temperature. The catalyst was then placed in a planetary ball mill and ground for 2 hours to obtain an amphiphilic transesterification catalyst.
[0038] The average particle diameter of the amphiphilic transesterification catalyst was determined to be 51 μm using a laser particle size analyzer, and its basicity was determined to be 11.8 using the Hammett indicator titration method. Using frying waste oil as raw material, at an alcohol-to-oil molar ratio of 10:1, a catalyst dosage of 10% of the oil weight, a reaction temperature of 25℃, and a reaction time of 35 min, the transesterification conversion rate reached 95.32%. The catalyst was washed twice with an equal volume of deionized water, resulting in a wash water pH of 7.12. Reuse experiments showed that even after three repetitions, the transesterification conversion rate still reached 91.4%.
[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A transesterification catalyst with amphiphilic properties, characterized in that, It is composed of the following raw materials in parts by weight: 100-120 parts toner, 10-40 parts active center, 70-100 parts dispersant, and appropriate amount of modifier.
2. The transesterification catalyst with amphiphilic properties according to claim 1, characterized in that, The carbon powder is one or more of coal-based activated carbon, coconut shell activated carbon, and wood-based activated carbon.
3. The transesterification catalyst with amphiphilic properties according to claim 1, characterized in that, The active center is one or more of sodium fluoride, potassium fluoride, potassium acetate, sodium acetate, potassium phosphate, sodium phosphate, potassium carbonate, sodium carbonate, sodium formate, and potassium formate.
4. The transesterification catalyst with amphiphilic properties according to claim 1, characterized in that, The dispersant is one or more of ethanol, methanol, propanol, tert-butanol, diethyl ether, ethyl acetate, benzene, and deionized water.
5. The transesterification catalyst with amphiphilic properties according to claim 1, characterized in that, The modifier is one or more of ethylene, acetylene, methane, ethane, and propane, or a combination thereof.
6. A method for preparing an amphiphilic transesterification catalyst as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Carbon powder pretreatment: Accurately weigh the carbon powder, calcine it under inert gas protection, and then cool it; (2) Active center loading: Accurately weigh the active center, add dispersant to dissolve it, add pretreated carbon powder, stir and mix, dry to obtain catalyst precursor; (3) Preparation of amphiphilic transesterification catalyst: The catalyst precursor was heated and calcined under inert gas protection, modified by introducing a modifier, and then switched to inert gas, cooled to room temperature, and ball-milled to obtain an amphiphilic transesterification catalyst.
7. The preparation method according to claim 6, characterized in that, The roasting temperature in step (1) is 500-900℃ and the time is 1-3h.
8. The preparation method according to claim 6, characterized in that, The mixing time in step (2) is 3-5 hours.
9. The preparation method according to claim 6, characterized in that, In step (3), the heating and calcination is carried out at a rate of 10℃ / min to 400-700℃, the flow rate of the modifier is 200-500mL / min, the modification time is 3-5h, and the ball milling is 1-2h.
10. The application of an amphiphilic transesterification catalyst as described in any one of claims 1-5 in the catalysis of transesterification reactions.