Analysis of Process Steps for Production of n-Butyl Acrylate by Esterification of Acrylic Acid and n-Butanol

acrylic acid (acrylic acid) is an important organic compound, which is widely used in chemical industry, plastics, coatings, textiles and other fields. As an ester compound, n-butyl acrylate (acrylate) has good solubility and chemical stability, and is widely used in the fields of synthetic resins, plastic modifiers and ink solvents. In the process of producing n-butyl acrylate, esterification reaction is a commonly used method, in which the esterification reaction of acrylic acid and n-butanol (n-butanol) is the main process route. In this paper, the process steps of producing n-butyl acrylate by esterification of acrylic acid and n-butanol will be analyzed in detail, and the relevant technical points will be discussed.

The basic principle of 1. esterification reaction

esterification reaction is the reaction of acid and alcohol under the action of acidic catalyst to produce ester and water. Acrylic acid is an unsaturated carboxylic acid whose chemical structure contains a carboxylic acid group ( -COOH) and an unsaturated double bond ( -CH-CH -2-). n-Butanol is a saturated monohydric alcohol with the chemical structure CH₂ CH₂ CH₂ CHOH. In the esterification reaction, the carboxylic acid group of acrylic acid reacts with the hydroxyl group of n-butanol to produce n-butyl acrylate and water.

The chemical equation of the esterification reaction is:

$$ \text{CH}2 =\text{CH}\text{COOH} \text{CH}2\text{CH}2\text{CH}2\text{CH}2\text{OH} \xrightarrow{\text {catalyst}} \text{CH}2 =\text{CH}\text{COOCH}2\text{CH}2\text \text{CH}2\text{CH}3} \text{H}_2\text{O} $$

the esterification reaction is a reversible reaction, so it is necessary to improve the conversion and yield of the reaction by optimizing the reaction conditions.

Process steps of esterification of 2. acrylic acid with n-butanol

the process steps for the production of butyl acrylate by esterification of acrylic acid and n-butanol can be divided into the following main stages:

1. Preparation and pretreatment of raw materials

• purification of acrylic acid acrylic acid usually exists in solution or solid form and needs to be purified by distillation or crystallization to ensure its purity meets the reaction requirements.
• Purification of n-Butanol: n-Butanol needs to remove impurities and moisture, and is usually treated by distillation or filtration to avoid affecting the activity of the catalyst.
• Preparation of catalyst esterification reactions usually require acidic catalysts, such as sulfuric acid (H₂) or p-toluenesulfonic acid (p-toluenesulfonic acid). The catalyst needs to be prepared in advance, and its concentration and dosage should be controlled.

2. Control of reaction conditions

• reaction temperature the esterification reaction is usually carried out under heating conditions, and the reaction temperature is generally controlled between 80-120°C. Too high temperature may lead to increased side reactions, while too low temperature will reduce the reaction rate.
• reaction pressure: Since the esterification reaction is a reversible reaction, it usually needs to be carried out under a certain pressure to balance the reaction system. The reaction pressure is generally controlled at atmospheric pressure or slightly positive pressure.
• Raw material ratio: The molar ratio of acrylic acid to n-butanol needs to be formulated reasonably. Usually the molar ratio of acrylic acid to n-butanol is 1:2 to ensure the completeness of the reaction and the purity of the product.

3. Reaction and monitoring

• feeding and mixing: The purified acrylic acid, n-butanol and catalyst are added to the esterification reactor in proportion and mixed thoroughly.
• Reaction monitoring: Through online analyzer or sampling analysis, real-time monitoring of the reaction conversion rate, product concentration and side reactions to ensure that the reaction process is in the best state.
• Reaction termination: When the reaction reaches the expected conversion rate or product concentration, the reaction is stopped, and the subsequent product separation and purification are carried out.

4. Separation and purification of products

• aqueous and organic phase separation the n-butyl acrylate and water produced by the esterification reaction can be separated by layering, in which the organic phase is n-butyl acrylate, and the aqueous phase is water and unreacted alkyd substances.
• product refining: Through distillation, rectification or molecular distillation and other processes, to further remove impurities and low boiling point substances, improve the purity of n-butyl acrylate.
• By-product treatment: The water and unreacted raw materials generated by the reaction need to be recovered and treated to reduce resource waste and environmental pollution.

3. process optimization and quality control

in order to improve the yield and quality of n-butyl acrylate, process optimization and quality control are essential:

1. catalyst selection and optimization: Different catalysts have different effects on reaction activity and selectivity. The selection of efficient and stable catalysts can significantly improve the reaction efficiency and product quality.
2. optimization of reaction conditions: By adjusting the reaction temperature, pressure, raw material ratio and other parameters, the optimal reaction conditions are found to maximize the reaction conversion and product yield.
3. Improvement of Product Refining Process: The use of advanced separation and purification technologies, such as membrane separation, chromatographic separation, etc., can effectively improve the purity and quality of n-butyl acrylate.
4. Process Automation and Monitoring: By introducing automatic control system and online monitoring technology, the reaction process can be tracked in real time to ensure the stability and consistency of process parameters.

4. Summary

the esterification of acrylic acid and n-butanol to produce n-butyl acrylate is an efficient and economical process route, the core of which lies in the optimization of esterification reaction and the improvement of product separation technology. Through the rational selection of raw materials, catalysts and reaction conditions, and the optimization of each step in the reaction process, the yield and quality of n-butyl acrylate can be significantly improved, the production cost can be reduced, and the negative impact on the environment can be reduced.

With the continuous advancement of technology, the process of esterification of acrylic acid with n-butanol will be further improved to provide more high-quality n-butyl acrylate products for downstream applications.