Background and overview[1][2]
As an alkaline earth metal alkoxide, calcium methoxide has the advantages of strong alkalinity, low solubility in methanol, and long service life. It can be used to catalyze the ester methoxybutanol exchange reaction to prepare biodiesel.
Apply[1-4]
1. Preparation of biodiesel by transesterification of rapeseed oil catalyzed by calcium methoxide
Liu Xuejun and others studied the reaction performance of calcium methoxide solid alkali catalyst to catalyze the transesterification reaction of rapeseed oil and methanol to produce biodiesel. They analyzed the specific surface area, total pore volume, average pore size and thermal stability of calcium methoxide, and studied The effects of reaction temperature, catalyst dosage and alcohol-to-oil molar ratio on biodiesel yield were studied.
Analysis method:
The scanning electron microscope used a Hitachi JEOL JSM7401F microscope with an operating voltage of 1.0 kV. The specific surface area, total pore volume and average pore diameter were analyzed using a QuantachromeAutosorb-1-C physical-chemical adsorption instrument. The degassing temperature of the catalyst sample was 150 °C and the degassing time was 1.5 h. Thermogravimetric analysis
Use a TA-449C thermogravimetric analyzer from the German Netzsch Company to increase the temperature from 25 ℃ to 800 ℃ in an oxygen atmosphere at a heating rate of 10 ℃/min. The solubility of calcium methoxide in alcohol was measured using the HITACHIZ-5000 atomic absorption instrument. Before the test, first put the block calcium methoxide at the bottom of the test tube, slowly add alcohol, and after holding at the specified temperature for 2 hours, take 5mL of the solution and put it into 10 mL centrifuge tube, evaporate the alcohol at 85°C, then add 5 mL of ultrapure water containing 1% hydrochloric acid to dissolve calcium methoxide, and finally test the calcium ion concentration in the ultrapure water using the flame method in an atomic absorption instrument. The content and components of fatty acid methyl esters were analyzed using HP GC5890-Ⅱ gas chromatograph. The capillary column was HP-INNOWAX (30m×0.15 mm). Nitrogen was used as the carrier gas. The flow rate was 30 mL/min and the split ratio was 10:1. The gas chromatography inlet temperature is 240°C, and the detector temperature is 300°C. The internal standard was methyl heptadecanoate dissolved in n-hexane at a concentration of 4 mg/L. Take 4 μL of the treated sample each time, dissolve it in 300 μL n-hexane, then add 100 μL n-hexane solution with internal standard dissolved in it, mix evenly, and then take 2 μL and inject it into the chromatograph. The gas chromatograph automatically gives the content of each component and the yield of fatty acid methyl ester based on the standard curve drawn in advance with standards.
The calcium methoxide solid alkali catalyst has strong alkalinity, good thermal stability, and low solubility in alcohol. It mainly plays a heterogeneous catalytic role and can effectively catalyze the transesterification of rapeseed oil to produce biodiesel. The optimal process conditions are: catalyst dosage 2.0%, reaction temperature 65°C, alcohol to oil molar ratio 22:1, reaction time 2.5h. Under this process condition, the biodiesel yield can reach 95%.
2. CN201710902486.1 discloses a method for preparing cyclopropylamine intermediate methyl cyclopropanecarboxylate. First, in a sealed reaction kettle, methanol is added dropwise to calcium carbide to generate calcium methoxide and acetylene; then at 60°C At a temperature of ~120°C, γ-chlorobutyric acid methyl ester is added to calcium methoxide. During the reaction, the temperature is controlled to be constant, and the methanol produced during the reaction is collected, and then methyl cyclopropanecarboxylate is obtained through distillation. The method of the invention has a simple process, requires few types of raw materials required for production, and some raw materials can be reused. The product yield is high, the quality is good, and it is safe and environmentally friendly.
3. CN201410425204.X involves a method for preparing boron-10 acid using boron trifluoride-10. Using anhydrous methanol as the solvent, boron-10 trifluoride reacts with calcium methoxide to generate boron-10 acid trimethyl ester. After solid-liquid separation of the reaction product, the liquid phase mixture is hydrolyzed to obtain boron-10 acid. The method of the present invention is divided into two processes: esterification and hydrolysis. During the esterification process, methanol is used as the solvent, and boron-10 trifluoride and calcium methoxide are reacted to obtain a mixture of boron-10 acid trimethyl ester and methanol. The reaction product is distilled, and the distillate is hydrolyzed to obtain a mixed solution of boric acid, methanol and water. After concentration and crystallization, boron-10 acid is obtained. The solid by-product after distillation has a single content, and its main component is calcium fluoride. The yield of boron-10 acid obtained by this method reaches more than 95.2%, and the purity of boric acid detected by the detection method of GBT12684-2006 can reach more than 99.7%.
IV. CN201810814882.3 relates to a preparation method of diallyl terephthalate, adding dimethyl terephthalate to the reactor.Ester, propylene alcohol, calcium methoxide and/or calcium ethoxide, start stirring, raise the temperature to 90~145℃ for reaction, keep the temperature at the top of the distillation column between 60~95℃, keep the reaction, take samples and detect, diterephthalate Stop heating when the methyl ester content is less than 0.5%; cool down to below 100°C, add water and acid, continue to cool down to 60°C, and let it stand for layering; remove the layer, wash it with water, layer it into layers, raise the temperature, and remove a small amount of water by vacuum distillation to obtain benzene. Diallyl dicarboxylate. This method greatly improves the efficiency of the transesterification reaction, shortens the time of the transesterification reaction, does not require decolorization, has low product color, improves product quality, and the catalyst separation is simple, rapid and thorough, and reduces the cost of catalyst treatment; the overall process It is more simplified, more adaptable to advanced operating methods such as automated production, and improves the automation level of the overall process.
Preparation[2]
Calcium methoxide synthesis reaction: In a sealed reactor, add methanol dropwise to calcium carbide, where the molar ratio of calcium carbide to methanol is 1:2~6 to generate calcium methoxide.
Main reference materials
[1] Liu Xuejun, Pu Xianglan, Wang Yujun, Zhu Shenlin. Research on the preparation of biodiesel by transesterification of rapeseed oil catalyzed by calcium methoxide [J]. Petroleum Refining and Chemical Engineering, 2007(10):21-24.
[2] CN201710902486.1 Preparation method of cyclopropylamine intermediate methyl cyclopropanecarboxylate
[3] CN201410425204.X Method for preparing boron-10 acid using boron trifluoride-10
[4] CN201810814882.3 Preparation method of diene isoparaffin propyl terephthalate
