Process for preparing biodiesel

Abstract

The invention relates to a technique used for preparing biodiesel, which takes rough vegetable oil and industrial methanol as raw materials and employs compound basic catalyst to carry out ester exchange reaction, and reaction pressure is 0.2MPa to 0.5MPa, reaction temperature is 70 DEG C to 140 DEG C and reaction time is 3 to 50 minutes; the materials after reaction go through sedimentation, flash vaporization and rectification under vacuum and then treatment technique acquired biodiesel products. The preparation method of the invention can effectively improve the speed of the ester exchangereaction, shorten reaction time, does not need to refine the raw materials and has simple technique, furthermore, reaction condition is moderate, the catalyst quantity used is small, conversion ratiois high and post treatment does not produce a great deal of waste water. The highest conversion ratio of the raw materials reaches 99 percent, and the purity, dynamic viscosity, acid value, octane number, glycerin content, saponification number, etc. of the obtained biodiesel all meet to standards of 0 model biodiesel.

Description

technical field

[0001] The invention relates to a process for producing biodiesel by transesterification, in particular to a method for synthesizing biodiesel under alkali catalysis by using crude vegetable oil and industrial methanol as raw materials. Background technique

[0002] At present, biodiesel is mainly produced by the transesterification reaction of animal and vegetable oils and some short-chain hydrocarbons (methanol, ethanol, etc.) under acid, base catalysis, enzyme catalysis or supercritical conditions.

[0003] The traditional transesterification reaction uses strong acid and strong base homogeneous catalysts, and the reaction is carried out under the conditions of normal pressure and about 60°C (below the boiling point of methanol). The reaction conditions are mild, but the reaction time often takes more than 1 hour. The conversion rate of oil to reach 95%. Wherein strong acid is used as catalyst, because the reaction speed is slow, is generally used in the ...

Examples

Embodiment 1

[0025] Embodiment 1: single kettle batch operation synthetic biodiesel

[0026] First take 4.788kg KOH, 0.145kg NaOH and 0.067kg Ca(OH) 2 Prepare composite catalyst, mix 5kg composite catalyst and 209kg industrial methanol in a sealed reactor with stirring device, then charge 1000kg crude vegetable oil. Under the detection and control of the thermocouple and pressure instrument in the reactor, adjust the rotation speed of the reactor stirrer so that the temperature of the reactor reaches 130°C and the pressure reaches 0.4MPa within 10 minutes, and then water-cools to room temperature immediately. Transfer the mixture in the reactor to a settler and let it stand for 120 minutes. The mixture is divided into two layers: the lower layer is a glycerol layer, and the upper layer is a biodiesel layer. The biodiesel layer is subjected to vacuum distillation at 60° C. and a vacuum of 0.0967 MPa to remove methanol, and then continued at 220° C. to obtain a refined biodiesel product. T...

Embodiment 2

[0028] This example is based on a throughput of 1,600 kg / h. The main parameters are shown in Table 1 and Table 2, and the process flow is as follows figure 1 shown.

[0029] Compound the catalyst according to the method and ratio of Example 1, then configure the methanol / alkali solution in the ratio of catalyst to industrial methanol mass ratio of 2.3:100. The ratio of the amount is continuously added in the reactor 1 with stirring at a ratio of 6:1, the temperature in the kettle is 88° C., the pressure is 0.2 MPa, the residence time of the material is 4 minutes, and the conversion rate of vegetable oil reaches 39%. Immediately after the material is pressurized by the pump 2, it is continuously sent into the reactor 3 with stirring. The temperature in the reactor is 110° C., the pressure is 0.3 MPa, the residence time of the material is 4.3 minutes, and the conversion rate of vegetable oil reaches 78%. Then the material is continuously fed into the stirred reactor 5 after be...

Embodiment 3

[0036] This example is based on a throughput of 1,600 kg / h. process such as figure 2 shown. The operating parameters are shown in Table 3, Table 4, and Table 5.

[0037] Compound catalyst according to the method and ratio of Example 1, then configure methanol / alkali solution according to the ratio in Example 2, under normal temperature, methanol / alkali solution and crude vegetable oil are continuously in the ratio of 6:1 according to the amount of substance Add the pre-mixing mixer 13, after mixing evenly, the material is pressurized to 0.3MPa by the pump 14, and then exchanges heat with the reacted material in the first preheater 15, and the temperature rises to 70°C, and then enters the second preheater 16. The temperature rises to 130°C, and then the material is pressurized to 0.7MPa by the pump 17 and then enters the tubular reactor 18. A static mixer is used inside the tube to enhance heat transfer. The material stays in the reactor for 3 minutes, and the conversion ...

technical field

[0001] The invention relates to a process for producing biodiesel by transesterification, in particular to a method for synthesizing biodiesel under alkali catalysis by using crude vegetable oil and industrial methanol as raw materials. Background technique

[0002] At present, biodiesel is mainly produced by the transesterification reaction of animal and vegetable oils and some short-chain hydrocarbons (methanol, ethanol, etc.) under acid, base catalysis, enzyme catalysis or supercritical conditions.

[0003] The traditional transesterification reaction uses strong acid and strong base homogeneous catalysts, and the reaction is carried out under the conditions of normal pressure and about 60°C (below the boiling point of methanol). The reaction conditions are mild, but the reaction time often takes more than 1 hour. The conversion rate of oil to reach 95%. Wherein strong acid is used as catalyst, because the reaction speed is slow, is generally used in the ...

Examples

Embodiment 1

[0025] Embodiment 1: single kettle batch operation synthetic biodiesel

[0026] First take 4.788kg KOH, 0.145kg NaOH and 0.067kg Ca(OH) 2 Prepare composite catalyst, mix 5kg composite catalyst and 209kg industrial methanol in a sealed reactor with stirring device, then charge 1000kg crude vegetable oil. Under the detection and control of the thermocouple and pressure instrument in the reactor, adjust the rotation speed of the reactor stirrer so that the temperature of the reactor reaches 130°C and the pressure reaches 0.4MPa within 10 minutes, and then water-cools to room temperature immediately. Transfer the mixture in the reactor to a settler and let it stand for 120 minutes. The mixture is divided into two layers: the lower layer is a glycerol layer, and the upper layer is a biodiesel layer. The biodiesel layer is subjected to vacuum distillation at 60° C. and a vacuum of 0.0967 MPa to remove methanol, and then continued at 220° C. to obtain a refined biodiesel product. T...

Embodiment 2

[0028] This example is based on a throughput of 1,600 kg / h. The main parameters are shown in Table 1 and Table 2, and the process flow is as follows figure 1 shown.

[0029] Compound the catalyst according to the method and ratio of Example 1, then configure the methanol / alkali solution in the ratio of catalyst to industrial methanol mass ratio of 2.3:100. The ratio of the amount is continuously added in the reactor 1 with stirring at a ratio of 6:1, the temperature in the kettle is 88° C., the pressure is 0.2 MPa, the residence time of the material is 4 minutes, and the conversion rate of vegetable oil reaches 39%. Immediately after the material is pressurized by the pump 2, it is continuously sent into the reactor 3 with stirring. The temperature in the reactor is 110° C., the pressure is 0.3 MPa, the residence time of the material is 4.3 minutes, and the conversion rate of vegetable oil reaches 78%. Then the material is continuously fed into the stirred reactor 5 after be...

Embodiment 3

[0036] This example is based on a throughput of 1,600 kg / h. process such as figure 2 shown. The operating parameters are shown in Table 3, Table 4, and Table 5.

[0037] Compound catalyst according to the method and ratio of Example 1, then configure methanol / alkali solution according to the ratio in Example 2, under normal temperature, methanol / alkali solution and crude vegetable oil are continuously in the ratio of 6:1 according to the amount of substance Add the pre-mixing mixer 13, after mixing evenly, the material is pressurized to 0.3MPa by the pump 14, and then exchanges heat with the reacted material in the first preheater 15, and the temperature rises to 70°C, and then enters the second preheater 16. The temperature rises to 130°C, and then the material is pressurized to 0.7MPa by the pump 17 and then enters the tubular reactor 18. A static mixer is used inside the tube to enhance heat transfer. The material stays in the reactor for 3 minutes, and the conversion ...

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