Method for removing water in continuous esterifying process

Abstract

The invention discloses a method for removing water in a continuous esterifying process. According to the method, a used fixed bed reactor is partitioned into an upper segment, a middle segment and a lower segment, high-boiling-point substances are introduced into the fixed bed reactor from the upper segment, low-boiling-point substances are added from the lower segment, and the high-boiling-point substances and the low-boiling-point substances flow reversely in a fixed bed and are subjected to an esterification reaction under the action of a catalyst; carrier gas is introduced from the bottom of the fixed bed reactor, water generated in the esterification reaction and the low-boiling-point substances are introduced into a heat exchange along with the carrier gas from the top of the fixed bed, and a generated ester product is condensed and collected at the bottom of the fixed bed reactor; the water and low-boiling-point substances passing through the heat exchanger are introduced into a condenser for condensing, are introduced into a liquid recycling system in the form of liquid, and are introduced into a water-separating system to separate the low-boiling-point substances from the water. By adopting the method, water generated by the reaction is transferred out of a reaction system by using the carrier gas in order to promote the forward proceeding of the esterification reaction, so that continuous charging and discharging are ensured, the energy consumption is lowered, the product quality is stabilized, and a high-purity ester is obtained.

Description

technical field

[0001] The invention relates to a water removal process in the esterification reaction, in particular to a water removal method in the continuous esterification process. Background technique

[0002] Esterification is one of the most commonly used reactions in chemical production. Usually the corresponding ester is generated from acid or acid anhydride and alcohol under the action of acid catalyst. The traditional catalysts used are liquid inorganic acid compounds, such as sulfuric acid, hydrochloric acid, phosphoric acid, etc. When this type of catalyst is used, there are a series of problems such as catalyst corrosion equipment and post-treatment of spent catalyst. To solve this problem, research and development of solid acid catalysts, such as strong acid ion resins, solid superacids, molecular sieves, heteropolyacids, etc. The catalyst is fixed on the fixed-bed reactor, so that acid and alcohol can be fed continuously, reducing energy consumption, stab...

Examples

Embodiment 1

[0033] Preparation of ethyl laurate

[0034] Add D008 strongly acidic ion resin catalyst into the fixed bed reactor 6. Make lauric acid into 1 mol / L ethanol solution, add it from the upper part of the fixed bed reactor 6 at a rate of 1.0 mL / min, and add ethanol from the lower part of the fixed bed reactor at a rate of 0.5 mL / min. The carrier gas was nitrogen at a flow rate of 100 mL / min. The ethanol solution of lauric acid and the preheater temperature of ethanol are both 100°C, the temperature of the nitrogen preheater is 150°C, and the temperature of the fixed bed reactor is 100°C. The final yield of ethyl laurate is ≥99.2%.

Embodiment 2

[0036] Diethyl terephthalate

[0037] Add SO to the fixed bed reactor 4 2- / TiO 2Solid superacid catalyst. Terephthalic acid was made into a 1 mol / L ethanol solution, which was added at a rate of 1.0 mL / min from the upper part of the fixed-bed reactor, and ethanol was added at a rate of 1.0 mL / min from the lower part of the fixed-bed reactor. The carrier gas was argon with a flow rate of 15 mL / min. The temperature of the ethanol solution of terephthalic acid, ethanol and argon is all 120°C. The temperature of the fixed bed reactor was 120°C. The final conversion rate of terephthalic acid is ≥99.0%, and the selectivity of diethyl terephthalate is ≥98.5%.

Embodiment 3

[0039] Poly(hexanediol adipate)

[0040] Add H into the fixed bed reactor 3 PW 12 o 40 ·nH20 heteropolyacid catalyst. Mix adipic acid and hexanediol in equimolar amounts to prepare a dioxane solution with a single component concentration of 0.5 mol / L, and add it from the upper part of the fixed-bed reactor at a rate of 1.0 mL / min. The carrier gas was argon with a flow rate of 15 mL / min. The preheater temperature of the mixed solution was 150°C, and the preheating temperature of the argon gas was 200°C. The temperature of the fixed bed reactor was 150°C. The final reaction produces poly(hexanediol adipate) with a number average molecular weight of 2123.5.

technical field

[0001] The invention relates to a water removal process in the esterification reaction, in particular to a water removal method in the continuous esterification process. Background technique

[0002] Esterification is one of the most commonly used reactions in chemical production. Usually the corresponding ester is generated from acid or acid anhydride and alcohol under the action of acid catalyst. The traditional catalysts used are liquid inorganic acid compounds, such as sulfuric acid, hydrochloric acid, phosphoric acid, etc. When this type of catalyst is used, there are a series of problems such as catalyst corrosion equipment and post-treatment of spent catalyst. To solve this problem, research and development of solid acid catalysts, such as strong acid ion resins, solid superacids, molecular sieves, heteropolyacids, etc. The catalyst is fixed on the fixed-bed reactor, so that acid and alcohol can be fed continuously, reducing energy consumption, stab...

Examples

Embodiment 1

[0033] Preparation of ethyl laurate

[0034] Add D008 strongly acidic ion resin catalyst into the fixed bed reactor 6. Make lauric acid into 1 mol / L ethanol solution, add it from the upper part of the fixed bed reactor 6 at a rate of 1.0 mL / min, and add ethanol from the lower part of the fixed bed reactor at a rate of 0.5 mL / min. The carrier gas was nitrogen at a flow rate of 100 mL / min. The ethanol solution of lauric acid and the preheater temperature of ethanol are both 100°C, the temperature of the nitrogen preheater is 150°C, and the temperature of the fixed bed reactor is 100°C. The final yield of ethyl laurate is ≥99.2%.

Embodiment 2

[0036] Diethyl terephthalate

[0037] Add SO to the fixed bed reactor 4 2- / TiO 2Solid superacid catalyst. Terephthalic acid was made into a 1 mol / L ethanol solution, which was added at a rate of 1.0 mL / min from the upper part of the fixed-bed reactor, and ethanol was added at a rate of 1.0 mL / min from the lower part of the fixed-bed reactor. The carrier gas was argon with a flow rate of 15 mL / min. The temperature of the ethanol solution of terephthalic acid, ethanol and argon is all 120°C. The temperature of the fixed bed reactor was 120°C. The final conversion rate of terephthalic acid is ≥99.0%, and the selectivity of diethyl terephthalate is ≥98.5%.

Embodiment 3

[0039] Poly(hexanediol adipate)

[0040] Add H into the fixed bed reactor 3 PW 12 o 40 ·nH20 heteropolyacid catalyst. Mix adipic acid and hexanediol in equimolar amounts to prepare a dioxane solution with a single component concentration of 0.5 mol / L, and add it from the upper part of the fixed-bed reactor at a rate of 1.0 mL / min. The carrier gas was argon with a flow rate of 15 mL / min. The preheater temperature of the mixed solution was 150°C, and the preheating temperature of the argon gas was 200°C. The temperature of the fixed bed reactor was 150°C. The final reaction produces poly(hexanediol adipate) with a number average molecular weight of 2123.5.

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