CN101423472B - Method for improving oil and low carbon alcohol transesterification reaction rate and composition - Google Patents

Abstract

The invention relates to a method for improving transesterification reaction rate of grease and low-carbon alcohol ester, and provides a method for improving the reaction rate of an ester interchange method to produce biodiesel, which comprises the step of adding nonionic surfactant capable of reducing intermolecular interfacial energy between the grease and the lower alcohol in a reaction system. The invention also provides a composition for realizing the method, which comprises the following components: 0.1 to 50.0 percent of fatty alcohol-polyoxyethylene ether, 0.1 to 30.0 percent of alkyl phenol polyoxyethylene ether, 0.0 to 45.0 percent of polyoxyethylene hexitan fatty acid ester, 0.0 to 45.0 percent of hexitan fatty acid ester, 0.0 to 35.0 percent of castor oil polyethenoxy ether, 0.1 to 40.0 percent of triethanolamine, and 10 to 30 percent of multifunctional emulsifying agent. The method can remarkably improve the reaction rate of the ester interchange method.

Description

A method and composition for increasing the rate of transesterification reaction between oil and low-carbon alcohol

technical field

The invention relates to a method for increasing the reaction rate of transesterification between oil and low-carbon alcohol.

The invention also relates to compositions for carrying out the above methods.

Background technique

The world's energy shortage has become an indisputable fact. At present, the main method of industrial production of biodiesel is to produce low-carbon alcohol esters of fatty acids through the action of oil and low-carbon alcohols, which is the so-called "ester exchange method". However, how to improve the quality of biodiesel produced by transesterification (hereinafter referred to as biodiesel), reduce energy consumption, and save costs are still important research topics that countries all over the world pay attention to.

The production process directly affects the yield and quality of biodiesel. Studies have shown that there are five main factors affecting the yield and rate of biodiesel, which are: stirring intensity, catalyst dosage, molar ratio of oil to low-carbon alcohol, reaction time, and reaction temperature, among which stirring intensity has the greatest impact. It can be seen that the transesterification reaction belongs to the mass transfer control reaction. Therefore, when selecting the best process conditions, the stirring intensity should be satisfied as much as possible first. However, this will increase the power of the stirring device, thereby increasing the power consumption and the degree of wear of the stirring device, and increasing the production cost. In fact, even if the stirring speed is increased, the reaction time cannot be controlled within the optimal time (about 25 minutes) for the formation of the main reactant. The longer the production time, the more energy consumption and the high cost. Increasing the stirring speed is beneficial to improve the yield of transesterification reaction, because the more turbulent the material is, the greater the contact and collision probability between alcohol and oil molecules will be, and the reaction rate will also increase accordingly.

Contents of the invention

The purpose of the present invention is to provide a method for improving the reaction rate of producing biodiesel by transesterification. The method is to fully and finely disperse the low-carbon alcohol in the oil to form an "alcohol-in-oil microemulsion", reduce the interfacial energy between the oil and low-carbon alcohol molecules, and shorten the transesterification reaction time, or in the same During the reaction time, the conversion rate of the transesterification reaction is improved.

Therefore, the method for improving the reaction rate of producing biodiesel by transesterification method provided by the present invention is to add nonionic surfactant capable of reducing the interfacial energy between grease and lower alcohol molecules in the reaction system.

The function of adding surfactant is to fully and finely disperse lower alcohol in oil to form "alcohol-in-oil microemulsion".

In order to realize the above method, the applicant of the present invention specifically researched a composition to realize the above method.

The composition (m/m)% of the composition (m/m) for improving the transesterification reaction rate of oil and lower alcohols provided by the present invention is: 0.1-50.0% of fatty alcohol polyoxyethylene ether, 0.1-30.0% of alkylphenol polyoxyethylene ether, polyoxyethylene Sorbitan fatty acid ester 0.0-45.0%, sorbitan fatty acid ester 0.0-45.0%, castor oil polyoxyethylene ether 0.0-35.0%, triethanolamine 0.1-40.0%, multi-functional emulsifier 10-30% Wherein the concrete proportioning of multifunctional emulsifier is as follows:

Alkylbenzenesulfonic acid 30%

Laurylamide 25%

Polyterpenes 15%

N-cyclohexylthiophthalimide 15%

Phenol 15%

In the present invention, the above-mentioned composition capable of increasing the transesterification reaction rate of oils and lower alcohols is referred to as "quick-acting agent" or "quick-acting agent for transesterification reaction".

Fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, castor oil polyoxyethylene ether, triethanolamine, multifunctional emulsifier are all Excellent surfactant. Non-ionic surfactants RO-(CH ₂ CH ₂ O) _n H will not dissociate in water and highly hydrophilic alcohol solvents (methanol, ethanol, etc.), and their surface activity depends on the polarity of the molecule ( Hydrophilic) part and non-polar (lipophilic) part are shown. This kind of nonionic surfactant has good emulsifying and dispersing effects, and is stable in a wide pH range and temperature range. These surfactants contain alkyl groups or aryl groups with different carbon numbers, which constitute lipophilic and hydrophobic groups with different oily lengths, and respectively have hydrophilic and oil-repellent groups such as ester bonds, ether bonds, carboxyl groups, and alcohol amino groups. group.

The degree of lipophilicity and hydrophilicity of various surfactants varies, and they all have different hydrophilic and lipophilic values (HLB values). Adjust the content of each surfactant to change the HLB value of the quick-acting agent to suit different oils, and then promote the transesterification reaction between the oil and low-carbon alcohols.

These surfactants will be well coordinated and distributed at the oleyl-alcohol interface, the lipophilic group extends into the oil phase, and the hydrophilic group extends into the alcohol phase (alcohol and catalyst), thereby reducing the interfacial tension between the oil and alcohol phases, and the alcohol The phase (alcohol and catalyst) can be finely, uniformly and stably dispersed in the oil phase (vegetable oil or animal oil), forming an excellent alcohol-in-oil microemulsion. This micro-emulsion oil with quick-acting agent, under the process conditions such as suitable stirring intensity, catalyst consumption, the mol ratio of oil and methanol, reaction temperature, can shorten or shorten than the grease transesterification reaction time of no accelerator under the same conditions. Productivity increases.

Preparation method of quick-acting agent for transesterification reaction: according to the production formula of quick-acting agent, put the raw materials into the enamel or stainless steel reaction tank in turn, heat, when the temperature rises to 60-65 (≤65) ℃, start stirring, the stirring speed is 60r/min , Stop heating for about 40 minutes. When cooling to 40°C, stop stirring, and take samples for inspection according to the quick-acting agent product standard. After passing the test, it can be packaged for future use or stored for delivery.

The main performance indicators of transesterification quick-acting agent products:

1) Appearance: dark brown transparent homogeneous liquid;

2) Smell: no special bad smell;

3) pH value: (20°C, 0.2% quick-acting agent aqueous solution), 6.5-8.5;

4) Density: (20°C, g/cm ³ ), 0.98～0.99;

5) Cold resistance: (0±2°C, 24h), return to room temperature, no abnormal phenomenon;

6) Heat resistance: (40±2°C, 24h), return to room temperature, no abnormal phenomenon.

The quick-acting agent provided by the invention can obviously improve the reaction rate of the transesterification method.

Detailed ways

The application method and performance of the product will be described below in combination with the test process of adding the quick-acting transesterification agent to the fruit oil and soybean oil.

Example:

1. Deployment of quick-acting agent for transesterification

Proportion 1: 42 grams of fatty alcohol polyoxyethylene ether, 23 grams of alkylphenol polyoxyethylene ether, 11.5 grams of polyoxyethylene sorbitan fatty acid ester, 0.5 grams of sorbitan fatty acid ester, castor oil polyoxyethylene Vinyl ether 0.5 grams, triethanolamine 22.5 grams.

Proportion 2: 40 grams of fatty alcohol polyoxyethylene ether, 20 grams of alkylphenol polyoxyethylene ether, 14 grams of polyoxyethylene sorbitan fatty acid ester, 0.4 grams of sorbitan fatty acid ester, castor oil polyoxyethylene Vinyl ether 0.0 g, triethanolamine 22.5 g.

Operation: Pour the above materials into a material mixer placed in a constant temperature water bath, stir, and heat up to 60°C; stop heating when the material is a yellow transparent uniform liquid, continue to stir and cool to 40°C. Take out the above materials and mix them with the multi-functional emulsifier at a ratio of 7:3 to form an esterification quick-acting agent.

Explanation: According to different formulas, the quick-acting agents prepared by the ratio 1 and the ratio 2 are recorded as quick-acting agent a and quick-acting agent b respectively.

The ratio of each component in quick-acting agent a:

Fatty alcohol polyoxyethylene ether 29.40%, alkylphenol polyoxyethylene ether 16.10%, polyoxyethylene sorbitan fatty acid ester 8.05%, sorbitan fatty acid ester 0.35%, castor oil polyoxyethylene ether 0.35% , triethanolamine 15.75%, multifunctional emulsifier 30%.

The ratio of each component in quick-acting agent b:

Fatty alcohol polyoxyethylene ether 28.90%, alkylphenol polyoxyethylene ether 14.46%, polyoxyethylene sorbitan fatty acid ester 10.12%, sorbitan fatty acid ester 0.28%, castor oil polyoxyethylene ether 0.00% , triethanolamine 16.24%, multifunctional emulsifier 30%.

2. Test device

1) Instruments: 1 magnetic stirrer, 1 250ml three-necked bottle, 1 glass serpentine cooler, 1 250ml separating funnel, 1 thermometer;

2) Installation: Select the rubber stopper suitable for the three necks of the three-necked bottle, respectively press the middle neck and the tail pipe of the cooler, the side neck and the thermometer, and the liquid drop pipe of the separatory funnel to punch holes, and connect the latex pipes of the water inlet and outlet of the cooler; Install the three-necked bottle on the bracket on the magnetic stirrer, and put it into the magnetic rotor; install the thermometer and separating funnel on both necks.

3. Reaction system

Edible soybean oil and glabra fruit oil were used as raw material oils for the biodiesel reaction, and other reaction conditions were adjusted appropriately to investigate the effect of quick-acting agents on the transesterification reaction, see Table 1 for details.

Table 1 List of reaction systems

4. Test process

Adding quick-acting agent for transesterification reaction, alkali-catalyzed transesterification of soybean oil, glabra fruit oil and other oils to produce biodiesel, and comparing the conversion rate of oil and the yield of glycerol to analyze the effect of quick-acting agent in transesterification reaction. The specific operation steps are as follows:

Add the weighed oil phase (soybean oil, quick-acting agent) into the three-necked bottle, add the weighed alcohol phase (methanol, catalyst sodium methoxide) into the separatory funnel, and shake the sodium methoxide into methanol; open Switch on the magnetic stirrer and heat the oil phase in the three-neck flask at high gear; when the temperature rises to 65°C, turn on the cooling water of the cooler, magnetic stirring, and a separatory funnel, and add the alcohol phase to the oil phase. At this time, the material is cooled, and the heating rate is increased to make the temperature rise back to 60°C. And control it at 60±3°C, react for about 25 minutes, change to low gear or stop heating. Gradually cool the material to 50°C, and the reaction time is 40 minutes (or 30 minutes).

Cool the resulting material after the reaction to room temperature, pour it into a separatory funnel and let it stand, separate the products such as glycerol in the lower layer, weigh and record. Conversion was calculated by mass of glycerol or by analysis of methyl ester yield by gas chromatography.

5. Comparison of results

Table 1 has listed the conversion rate of the transesterification reaction of different reaction systems, and the results are as follows:

The impact of table 1 quick-acting agent on transesterification conversion rate

6. Result analysis

1) Comparing the transesterification conversion rates of systems A, B and C, the results show that the addition of quick-acting agents is beneficial to the improvement of the transesterification conversion rate and the shortening of the transesterification reaction time.

2) Comparing the transesterification conversion rates of systems A, B, C and D, E, F, the results show that the addition of quick-acting agents can promote the transesterification of different feedstock oils to a certain extent.

3) Comparing the transesterification conversion rates of systems D, E, and F, the results show that different oils should be added with a specific transesterification quick-acting agent suitable for the oil.

Claims (5)

1. a method that improves grease and low-carbon-ester transesterification reaction rate is characterized in that adding the nonionogenic tenside that can reduce grease and the intermolecular interfacial energy of lower alcohol in reaction system;

Wherein said nonionogenic tenside is a fatty alcohol-polyoxyethylene ether 0.1～50.0%, alkylphenol polyoxyethylene 0.1～30.0%, polyoxyethylene sorbitan fatty acid ester 0.0～45.0%, sorbitan fatty acid ester 0.0～45.0%, castor oil polyoxyethylene ether 0.0～35.0%, trolamine 0.1～40.0%, multi-functional emulsifier 10～30%; Wherein the concrete proportioning of multi-functional emulsifier is as follows:

Alkyl benzene sulphonate (ABS) 30%

Lauryl alcohol acid amides 25%

Poly terpenes 15%

N-cyclohexyl thio phthalimide 15%

Phenol 15%.

2. method according to claim 1, it is characterized in that fatty alcohol-polyoxyethylene ether 28--30%, alkylphenol polyoxyethylene 14--17%, polyoxyethylene sorbitan fatty acid ester 8--11%, sorbitan fatty acid ester 0.28--0.35%, castor oil polyoxyethylene ether 0--0.35%, trolamine 15--17%, multi-functional emulsifier 30%.

3. composition that improves grease and low-carbon-ester transesterification reaction rate is characterized in that comprising following component:

Fatty alcohol-polyoxyethylene ether 0.1～50.0%, alkylphenol polyoxyethylene 0.1～30.0%, polyoxyethylene sorbitan fatty acid ester 0.0～45.0%, sorbitan fatty acid ester 0.0～45.0%, castor oil polyoxyethylene ether 0.0～35.0%, trolamine 0.1～40.0%, multi-functional emulsifier 10～30%; Wherein the concrete proportioning of multi-functional emulsifier is as follows:

Alkyl benzene sulphonate (ABS) 30%

Lauryl alcohol acid amides 25%

Poly terpenes 15%

N-cyclohexyl thio phthalimide 15%

Phenol 15%.

4. composition according to claim 3, it is characterized in that fatty alcohol-polyoxyethylene ether 28--30%, alkylphenol polyoxyethylene 14--17%, polyoxyethylene sorbitan fatty acid ester 8--11%, sorbitan fatty acid ester 0.28--0.35%, castor oil polyoxyethylene ether 0--0.35%, trolamine 15--17%, multi-functional emulsifier 30%.

5. preparation is characterized in that each component is dropped into vessel in heating successively, when temperature rises to 60～65 ℃ as claim 3 or 4 described method for compositions, start stirring, stirring velocity is 60r/min, and controlled temperature is not higher than 65 ℃, stops heating about 40min; Stop when being cooled to 40 ℃ stirring, get final product.