阅读说明：本技术 一种基于生物柴油制备脂肪酸丁酯的连续化生产方法 (Continuous production method for preparing fatty acid butyl ester based on biodiesel ) 是由 聂勇 梁晓江 吴振宇 傅俊红 解庆龙 谈臻炫 吴凤娇 卢美贞 计建炳 于 2019-10-22 设计创作，主要内容包括：本发明公开了一种基于生物柴油制备脂肪酸丁酯的连续化生产方法,将n级依次串联的气液反应器作为反应装置,各级气液反应器内的温度均维持在反应温度,原料生物柴油与催化剂混合的反应混合液从第一级气液反应器流到第n级气液反应器,n股丁醇分别通入到各级气液反应器内与反应混合液进行酯交换反应,每一级气液反应器内均持续蒸出未反应的丁醇和副产甲醇混合蒸汽,将蒸出的丁醇和甲醇混合蒸汽进行分离、提纯,得到高纯甲醇和丁醇；对第n级气液反应器内流出的反应液,经后处理得到脂肪酸丁酯产品。本发明通过多级气液反应器串联的方式实现了脂肪酸丁酯的连续化生产,该生产方法具有工艺简单、安全高效、可连续生产高品质脂肪酸丁酯的优点。(The invention discloses a continuous production method for preparing fatty acid butyl ester based on biodiesel, which comprises the steps of taking n stages of gas-liquid reactors connected in series in sequence as a reaction device, maintaining the temperature in each stage of gas-liquid reactor at the reaction temperature, allowing reaction mixed liquid of raw material biodiesel and a catalyst to flow from a first stage of gas-liquid reactor to an nth stage of gas-liquid reactor, introducing n strands of butanol into each stage of gas-liquid reactor respectively to perform ester exchange reaction with the reaction mixed liquid, continuously evaporating unreacted butanol and byproduct methanol mixed steam in each stage of gas-liquid reactor, and separating and purifying the evaporated butanol and methanol mixed steam to obtain high-purity methanol and butanol; and (3) carrying out post-treatment on the reaction liquid flowing out of the nth stage gas-liquid reactor to obtain a fatty acid butyl ester product. The method realizes the continuous production of the fatty acid butyl ester by the mode of serially connecting the multi-stage gas-liquid reactors, and has the advantages of simple process, safety, high efficiency and capability of continuously producing the high-quality fatty acid butyl ester.)

1. A continuous production method for preparing fatty acid butyl ester based on biodiesel is characterized by comprising the following steps: the method takes n stages of gas-liquid reactors connected in series in sequence as a reaction device for continuously producing the fatty acid butyl ester, and comprises the following steps:

1) mixing raw material biodiesel with a non-acid catalyst to obtain a reaction mixed solution; the temperature in each stage of gas-liquid reactor is maintained at the reaction temperature, and the reaction mixed liquid flows from the first stage of gas-liquid reactor to the nth stage of gas-liquid reactor in a continuous feeding mode; the non-acid catalyst adopts sodium methoxide, potassium carbonate or butyl titanate;

simultaneously, dividing the butanol into n strands, respectively introducing the n strands of butanol into each stage of gas-liquid reactor to perform ester exchange reaction with the reaction mixed liquid, and continuously evaporating unreacted butanol and byproduct methanol mixed steam in each stage of gas-liquid reactor under the condition of reaction temperature;

2) mixing butanol and methanol mixed steam evaporated from each stage of gas-liquid reactor in the step 1), sending the mixture to a methanol rectification working section in a gas phase feeding mode for separation and purification so as to recover methanol components in the mixture, and obtaining high-purity methanol and recycled butanol; collecting reaction liquid flowing out of the nth stage gas-liquid reactor in the step 1), and carrying out post-treatment on the collected reaction liquid to obtain a fatty acid butyl ester product.

2. The continuous production method for preparing fatty acid butyl ester based on biodiesel according to claim 1, characterized in that: the n is an integer of 2 to 10, preferably 4 to 8.

3. The continuous production method for preparing fatty acid butyl ester based on biodiesel according to claim 1, characterized in that: the operation pressure in each stage of gas-liquid reactor is normal pressure, and the reaction temperature in each stage of gas-liquid reactor is within the range of 130-200 ℃.

4. The continuous production method for preparing fatty acid butyl ester based on biodiesel according to claim 1, characterized in that: the ratio of the molar flow rate of the biodiesel delivery to the molar flow rate of butanol introduced into the first-stage gas-liquid reactor is 0.5-0.7: 1, the ratio of the molar flow rate of the biodiesel to the molar flow rate of butanol introduced into the gas-liquid reactors at each middle stage is 1.5-3: 1, the ratio of the molar flow of the biodiesel to the molar flow of the butanol introduced into the nth stage gas-liquid reactor is 0.8-0.95: 1.

5. the continuous production method for preparing fatty acid butyl ester based on biodiesel according to claim 1, characterized in that: the gas-liquid reactor is a tower reactor, a kettle reactor or a supergravity bed reactor.

6. The continuous production method for preparing fatty acid butyl ester based on biodiesel as claimed in claim 1, wherein the collected reaction solution is post-treated by the steps of: flash evaporating the reaction liquid while the reaction liquid is hot to remove butanol components in the reaction liquid, and sending the residue after flash evaporation to a butyl ester rectification section for separation and purification to extract fatty acid butyl ester components in the reaction liquid, so as to obtain biological asphalt and fatty acid butyl ester products with purity of more than 99.5%; wherein, the butanol separated by flash evaporation is mixed with the recycled butanol obtained in the step 2) and then recycled for the ester exchange reaction process in the front n-1 stage gas-liquid reactor.

7. The continuous production method for preparing fatty acid butyl ester based on biodiesel according to claim 6, wherein the mixed solution of butanol separated by flash evaporation and recycled butanol obtained in step 2) is recorded as a recycled butanol product, and the specific recycling process of the recycled butanol product is as follows: dividing the recovered butanol product into n-1 strands, respectively introducing the n-1 strands into the first n-1-stage gas-liquid reactor to perform transesterification with the reaction mixed liquid, and additionally introducing 1 strand of fresh butanol into the nth gas-liquid reactor to perform transesterification with the reaction mixed liquid.

8. The continuous process for preparing butyl fatty acid ester based on biodiesel as claimed in claim 6, wherein the absolute pressure of the flash evaporation is 1500-5000 Pa.

9. The continuous production method of fatty acid butyl ester based on biodiesel according to claim 1, wherein the flow rate of butanol introduced into the nth stage gas-liquid reactor is greater than that of butanol introduced into the middle stage gas-liquid reactor and is less than that of butanol introduced into the first stage gas-liquid reactor.

Technical Field

The invention belongs to the technical field of fatty acid butyl ester preparation, and particularly relates to a continuous production method for preparing fatty acid butyl ester based on biodiesel.

Background

The fatty acid butyl ester is a light yellow transparent oily liquid at normal temperature, is an organic chemical intermediate with wide application, and can be used as biodiesel, lubricating oil, plasticizer and the like. At present, the preparation of the fatty acid butyl ester is mainly obtained by carrying out ester exchange reaction on natural animal and vegetable oil (such as soybean oil, rapeseed oil, peanut oil and the like) under the catalysis of concentrated sulfuric acid, the industrial process technology is mature, but the use process of the concentrated sulfuric acid catalyst is easy to cause partial carbonization of raw materials, so that the problems of product color deepening, purity reduction, yield reduction, complex post-treatment process, serious equipment corrosion, serious wastewater pollution and the like are caused, and the development of the industry is severely restricted. In addition, the current intermittent production mode of the fatty acid butyl ester has the defects of low efficiency, high energy consumption, low utilization rate of butanol, unstable product quality, great potential safety hazard and the like.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a continuous production method of fatty acid butyl ester, which is particularly suitable for continuously preparing the fatty acid butyl ester by using biodiesel.

The continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized by comprising the following steps of: the method takes n stages of gas-liquid reactors connected in series in sequence as a reaction device for continuously producing the fatty acid butyl ester, and comprises the following steps:

1) mixing raw material biodiesel with a non-acid catalyst to obtain a reaction mixed solution; the temperature in each stage of gas-liquid reactor is maintained at the reaction temperature, and the reaction mixed liquid flows from the first stage of gas-liquid reactor to the nth stage of gas-liquid reactor in a continuous feeding mode; simultaneously, dividing the butanol into n strands, respectively introducing the n strands of butanol into each stage of gas-liquid reactor to perform ester exchange reaction with the reaction mixed liquid, and continuously evaporating unreacted butanol and byproduct methanol mixed steam in each stage of gas-liquid reactor under the condition of reaction temperature;

2) mixing butanol and methanol mixed steam evaporated from each stage of gas-liquid reactor in the step 1), sending the mixture to a methanol rectification working section in a gas phase feeding mode for separation and purification so as to recover methanol components in the mixture, and obtaining high-purity methanol and recycled butanol; collecting reaction liquid flowing out of the nth stage gas-liquid reactor in the step 1), and carrying out post-treatment on the collected reaction liquid to obtain a fatty acid butyl ester product.

The continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized by comprising the following steps of: the n is an integer of 2 to 10, preferably 4 to 8.

The continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized by comprising the following steps of: the operation pressure in each stage of gas-liquid reactor is normal pressure, and the reaction temperature in each stage of gas-liquid reactor is within the range of 130-200 ℃.

The continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized by comprising the following steps of: the ratio of the molar flow rate of the biodiesel delivery to the molar flow rate of butanol introduced into the first-stage gas-liquid reactor is 0.5-0.7: 1, the ratio of the molar flow rate of the biodiesel to the molar flow rate of butanol introduced into the gas-liquid reactors at each middle stage is 1.5-3: 1, the ratio of the molar flow of the biodiesel to the molar flow of the butanol introduced into the nth stage gas-liquid reactor is 0.8-0.95: 1.

the continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized by comprising the following steps of: the gas-liquid reactor is a tower reactor, a kettle reactor or a supergravity bed reactor, and the tower reactor can adopt an absorption tower device.

The continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized in that the collected reaction liquid is subjected to post-treatment and comprises the following steps: flash evaporating the reaction liquid while the reaction liquid is hot to remove butanol in the reaction liquid, and sending the residue after flash evaporation to a butyl ester rectification section for separation and purification to extract the fatty acid butyl ester component in the reaction liquid, so as to obtain the biological asphalt and the fatty acid butyl ester product with the purity of more than 99.5 percent; wherein, the butanol separated by flash evaporation is mixed with the recycled butanol obtained in the step 2) and then recycled for the ester exchange reaction process in the front n-1 stage gas-liquid reactor.

The continuous production method for preparing fatty acid butyl ester based on biodiesel is characterized in that mixed liquid of butanol separated by flash evaporation and recycled butanol obtained in the step 2) is recorded as a recycled butanol product, and the specific recycling process of the recycled butanol product is as follows: dividing the recovered butanol product into n-1 strands, respectively introducing the n-1 strands into the first n-1-stage gas-liquid reactor to perform transesterification with the reaction mixed liquid, and additionally introducing 1 strand of fresh butanol into the nth gas-liquid reactor to perform transesterification with the reaction mixed liquid.

The continuous production method for preparing the fatty acid butyl ester based on the biodiesel is characterized in that the absolute pressure of flash evaporation is 1500-5000 Pa.

The continuous production method for preparing fatty acid butyl ester based on biodiesel is characterized in that the flow of butanol introduced into the nth stage of gas-liquid reactor is greater than that of butanol introduced into the middle stages of gas-liquid reactors and is less than that of butanol introduced into the first stage of gas-liquid reactor.

According to the method, the fatty acid butyl ester can be continuously produced under the action of the conventional ester exchange reaction catalyst, but in order to avoid the technical problem that concentrated sulfuric acid and other acidic catalysts seriously corrode equipment, the non-acid catalyst is applied to the continuous production method for preparing the fatty acid butyl ester based on the biodiesel, the non-acid catalyst can be sodium methoxide, potassium carbonate, butyl titanate and other catalysts, and the experiment for continuously producing the fatty acid butyl ester verifies that the continuous production process is stable in operation and the purity and the quality of the fatty acid butyl ester product are high.

By adopting the technology, compared with the prior art, the invention has the following beneficial effects:

1. the method realizes the continuous production of preparing the fatty acid butyl ester by the biodiesel in a mode of serially connecting the multistage gas-liquid reactors, and utilizes the multistage gas-liquid transesterification reaction for producing the fatty acid butyl ester in the multistage serially connected gas-liquid reactors;

2. the reactant butanol is fed into each stage of gas-liquid reactor according to the metering mode of 'big end at two ends and small end at middle' to carry out multi-stage gas-liquid transesterification reaction, thereby improving the utilization rate of butanol to the maximum extent, breaking the equilibrium limitation of the transesterification reaction and improving the conversion rate of fatty acid methyl ester. This is because: the first-stage gas-liquid transesterification reaction adopts large-flow butanol feeding, ensures that high-concentration fatty acid methyl ester in the reactor performs transesterification reaction at the maximum reaction rate, and timely and quickly discharges the byproduct methanol through butanol steam, thereby accelerating the reaction rate. When the reaction mixture flows into the last stage gas-liquid reactor, the conversion rate of the fatty acid methyl ester is high (i.e. the concentration of the fatty acid methyl ester in the reaction mixture is kept low). And introducing large-flow butanol into the last stage gas-liquid reactor to ensure that the low-concentration fatty acid methyl ester performs ester exchange reaction at the fastest speed, introducing fresh butanol into the last stage gas-liquid reactor at the moment to prevent the methanol in the recovered butanol product from being insufficiently removed, and raising the conversion rate of the low fatty acid methyl ester to a certain extent, and desorbing, entraining and discharging a small amount of methanol at the fastest speed through a large amount of butanol steam, so that the balance limit of the ester exchange reaction is broken, and the product yield of the fatty acid butyl ester is improved. The middle gas-liquid transesterification reaction at each stage adopts butanol with less flow to carry out the transesterification reaction, and because the consumption of the reactant butanol required by the middle transesterification reaction at each stage is greatly reduced, the utilization rate of the butanol is improved to the maximum extent under the condition of ensuring the consumption of the butanol required by the transesterification reaction, and the cost is saved;

3. the methanol rectification section is combined with butanol obtained by flash evaporation and then reused in other gas-liquid transesterification reactions except the last stage of gas-liquid transesterification reaction, so that the consumption of butanol is reduced, the cost is saved, and a byproduct methanol product with the purity of more than 99.5 percent is obtained; the mixed steam of methanol and butanol generated by the gas-liquid transesterification directly enters a methanol rectification working section in a gas phase feeding mode, and the mixed hot steam is directly rectified to recover the methanol component in the mixed hot steam, so that the rectification energy consumption can be obviously reduced;

4. the method can continuously and stably produce the fatty acid butyl ester product with the purity of more than 99.5 percent through the synergistic effect of the multistage gas-liquid ester exchange reaction series connection, the flash evaporation and the butyl ester rectification working section, and is suitable for industrial production.

Drawings

FIG. 1 is a process flow diagram of the continuous production method for preparing fatty acid butyl ester based on biodiesel according to the invention.

Detailed Description

The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.