Energy-saving high-purity process for continuous production of acetic ether

Abstract

The invention discloses an energy-saving high-purity process for continuous production of ethyl acetate, which comprises the following steps of: preheating raw materials, namely mixing acetic acid and absolute ethyl alcohol according to a molar ratio of 1: 1.1, carrying out heat exchange and preheating on a mixed solution, enabling the preheated mixed solution to enter an esterification tower, reacting under the catalysis of a catalyst in the esterification tower, condensing and splitting phases of azeotrope at the top of the tower, and carrying out condensation and phase splitting on the azeotrope at the bottom of the tower; the water phase is sent to a recovery tower, the ester phase partially reflows, the other ester phase is sent to a rectifying tower for purification, and tail gas is absorbed by a vacuum pump and a condenser and then enters an RTO system for treatment. Methanesulfonic acid is used as an esterification catalyst instead of sulfuric acid, so that side reactions and impurities are reduced, and the product purity is improved; and high-temperature gas generated by reaction is used for heat exchange cooling, so that raw material preheating energy is saved, energy required by cooling is also reduced, energy utilization is improved, and environmental protection is realized.

Description

Technical Field

[0001] This invention relates to the field of ethyl acetate production technology, specifically to an energy-saving and high-purity process for the continuous production of ethyl acetate. Background Technology

[0002] Acetate esters are widely used in coatings, adhesives, pharmaceuticals, electronic cleaning agents, and other industries, with stable and rapidly growing market demand. Current industrial production of ethyl acetate typically employs an esterification process catalyzed by homogeneous strong acids (such as sulfuric acid or p-toluenesulfonic acid). This process has the following drawbacks: 1. Reaction equilibrium limitation: Esterification is a reversible reaction, and water is difficult to remove in time, resulting in a low conversion rate of acetic acid (approximately 91%-92%). 2. High energy consumption: The reaction and distillation separation are carried out separately, resulting in high steam consumption and low energy utilization. 3. High levels of by-product impurities: Sulfuric acid catalysts are highly corrosive, leading to corrosion problems in by-products and equipment, which affects product purity; 4. Significant environmental pressure: The wastewater has a high content of residual organic matter and exceeds the COD standard, increasing the burden of wastewater treatment.

[0003] Therefore, there is an urgent need to develop a new process that can reduce energy consumption and improve environmental performance while ensuring high yield and high purity. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a process for the continuous production of ethyl acetate that ensures purity and is energy-saving and environmentally friendly.

[0005] To achieve the above objectives, the present invention provides an energy-saving and high-purity process for the continuous production of ethyl acetate, which adopts the following technical solution: An energy-saving and high-purity process for the continuous production of ethyl acetate includes the following steps: preheating the raw materials, including mixing acetic acid and anhydrous ethanol at a molar ratio of 1:1.1, followed by heat exchange preheating of the mixture, and then the preheated mixture enters an esterification tower, where the reaction is catalyzed by a catalyst. The azeotrope at the top of the tower is condensed and separated into phases, with the aqueous phase sent to a recovery tower, and the ester phase partially refluxed and partially sent to a distillation tower for purification. The tail gas is absorbed by a vacuum pump and a condenser before entering an RTO system for treatment.

[0006] A further improvement of the energy-saving and high-purity process for continuous production of ethyl acetate in this invention is that a first connecting pipe is provided above the esterification tower, the first connecting pipe is connected to a condensing structure, the condensing structure is connected to a phase separator, a mixing tank is provided next to the condensing structure, the mixing tank is connected to the condensing structure, and the condensing structure is also connected to an outlet pipe.

[0007] A further improvement of the energy-saving and high-purity process for continuous production of ethyl acetate in this invention is that a second connecting pipe is provided above the distillation column, the second connecting pipe is connected to a second condensing structure, a second mixing tank is provided next to the second condensing structure, the second mixing tank is connected to the second condensing structure, and the second condensing structure is also connected to a second liquid outlet pipe.

[0008] A further improvement of the energy-saving and high-purity process for continuous production of ethyl acetate in this invention is that an auxiliary condensing structure is provided between the condensing structure and the phase separator, and the auxiliary condensing structure is connected to the cooling water tank.

[0009] A further improvement of the energy-saving and high-purity process for continuous production of ethyl acetate in this invention is that the phase separator is connected to a fixed water tank, the cooling water tank is also connected to the fixed water tank, and the fixed water tank is connected to the steam generator.

[0010] A further improvement of the energy-saving and high-purity process for the continuous production of ethyl acetate in this invention is that the catalyst is 0.5% (wt.) methanesulfonic acid.

[0011] Compared with the prior art, the beneficial effects of the present invention are: This invention uses methanesulfonic acid instead of sulfuric acid as an esterification catalyst, reducing side reactions and impurities and improving product purity; it utilizes the high-temperature gas generated by the reaction for heat exchange and cooling, saving energy for raw material preheating and reducing the energy required for cooling, thus improving energy utilization and achieving environmental protection. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the structure of the present invention; In the diagram: 1 Esterification tower, 2 Mixing tank, 3 Preheating tank, 4 Condensation structure, 5 Auxiliary condensation structure, 6 Phase separator, 7 Distillation tower, 8 Second condensation structure, 9 Second mixing tank. Detailed Implementation

[0013] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0014] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0015] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0017] like Figure 1 As shown, an energy-saving and high-purity process for the continuous production of ethyl acetate includes the following steps: preheating the raw materials, including mixing acetic acid and anhydrous ethanol at a molar ratio of 1:1.1, followed by heat exchange preheating of the mixture, and then the preheated mixture enters esterification tower 1. The reaction is carried out under the catalysis of the catalyst in the esterification tower. The azeotrope at the top of the tower is condensed and separated into phases. The aqueous phase is sent to the recovery tower, and part of the ester phase is refluxed and part is sent to the distillation tower 7 for purification. The tail gas is absorbed by a vacuum pump and condenser and then enters the RTO system for treatment.

[0018] A first connecting pipe is provided above the esterification tower, which is connected to the condensing structure 4. The condensing structure is connected to the phase separator 6. A mixing tank 2 is provided next to the condensing structure, which is connected to the condensing structure 4. The condensing structure is also connected to a liquid outlet pipe, which is connected to a collection box. The collection box is circulated and connected to the mixing tank. The liquid outlet pipe is also connected to a preheating box 3, which is connected to the esterification tower.

[0019] A second connecting pipe is provided above the distillation column, and the second connecting pipe is connected to the second condensing structure 8. A second mixing tank 9 is provided next to the second condensing structure, and the second mixing tank is connected to the second condensing structure. The second condensing structure is also connected to a second liquid outlet pipe.

[0020] An auxiliary condensing structure is installed between the condensing structure and the phase separator, and the auxiliary condensing structure is connected to the cooling water tank.

[0021] The phase splitter is connected to the fixed water tank, the cooling water tank is also connected to the fixed water tank, and the fixed water tank is connected to the steam generator.

[0022] The catalyst is 0.5% (wt.) methanesulfonic acid.

[0023] This invention uses methanesulfonic acid instead of sulfuric acid as an esterification catalyst to reduce side reactions and impurities, improve product purity, and continuously remove by-product water along with the azeotrope at the top of the esterification tower, thereby breaking the reaction equilibrium and improving the conversion rate. On the other hand, the heat at the top of the esterification tower and the distillation tower is utilized to reduce steam consumption and save energy.

[0024] Compared with traditional processes, the acetic acid conversion rate of this invention is ≥ 98%, significantly higher than the 91-92% of traditional processes; the purity of the ethyl acetate product is ≥ 99.6%, and the electronic grade product can reach 99.9%; steam consumption is reduced by 20-30%, achieving energy saving and consumption reduction; COD in wastewater is reduced by about 40%, significantly alleviating environmental pressure; the process has strong adaptability and is suitable for the production of both general-grade and electronic-grade products.

[0025] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An energy efficient high purity process for continuous production of ethyl acetate characterized in that, The raw material is preheated by the following steps: acetic acid and anhydrous ethanol are mixed at a molar ratio of 1:1.1, then the mixture is preheated by heat exchange, then the preheated mixture enters the esterification tower, the catalyst in the tower catalyzes the reaction, the azeotrope at the top of the tower is condensed and separated, the water phase is sent back to the recovery tower, the ester phase is partially refluxed and partially sent to the rectification tower for purification, and the tail gas is absorbed by a vacuum pump and a condenser and then enters the RTO system for treatment.

2. An energy efficient high purity process for continuous production of ethyl acetate as claimed in claim 1, wherein, A first connecting pipe is arranged above the esterification tower, the first connecting pipe is connected to a condensing structure, the condensing structure is connected to a phase separator, a mixing tank is arranged beside the condensing structure, the mixing tank is connected to the condensing structure, and the condensing structure is further connected to a liquid outlet pipe.

3. An energy efficient high purity process for continuous production of ethyl acetate as claimed in claim 2, wherein, A second connecting pipe is arranged above the rectification tower, the second connecting pipe is connected to a second condensing structure, a second mixing tank is arranged beside the second condensing structure, the second mixing tank is connected to the second condensing structure, and the second condensing structure is further connected to a second liquid outlet pipe.

4. The energy-efficient high purity process for continuous production of ethyl acetate as claimed in claim 3, wherein, An auxiliary condensing structure is arranged between the condensing structure and the phase separator, and the auxiliary condensing structure is connected to a cooling water tank.

5. An energy efficient high purity process for continuous production of ethyl acetate as claimed in claim 4 wherein, The phase separator is connected to a fixed water tank, the cooling water tank is also connected to the fixed water tank, and the fixed water tank is connected to a steam generator.

6. An energy efficient high purity process for continuous production of ethyl acetate as claimed in claim 5 wherein, The catalyst is methyl sulfonic acid with a concentration of 0.5% (wt.).

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