Method for continuously refining dimethyl 2, 6-naphthalate

A technology of dimethyl naphthalate and xylene, which is applied in the field of continuous refining of dimethyl 2,6-naphthalate, can solve the problems of clogging of filter plates, deterioration of color and air pollution, etc., and achieve stable and smooth output. The effect of improving the material, yield and purity, and improving the operation efficiency

Pending Publication Date: 2022-07-29
CCTEG CHINA COAL RES INST
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

After the material is transferred to the suction filter device, when it encounters the filter plate at normal temperature, the material will partially condense and cause the filter plate to be blocked, which will lead to unstable and smooth discharge, low operating efficiency, and a high yield of 2,6-NDC lower
[0007] 2. The recrystallization method used in the purification of 2,6-NDC is complicated to operate, and consumes a large amount of recrystallization solvent. Usually, the adsorbent is added to the solvent, which consumes more adsorbent, and the adsorbent cannot be recycled. use
[0008] 3. At present, 2,6-NDC is purified by vacuum distillation. The distillation temperature is too high (>270°C), which will easily lead to decarboxylation and decomposition of 2,6-NDC, and generate methyl 2-naphthoate as a by-product. Color deterioration
[0009] 4. In the current intermittent operation mode, during the process of material transfer, the solvent will volatilize into the air and cause air pollution

Method used

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  • Method for continuously refining dimethyl 2, 6-naphthalate
  • Method for continuously refining dimethyl 2, 6-naphthalate
  • Method for continuously refining dimethyl 2, 6-naphthalate

Examples

Experimental program
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Effect test

Embodiment 1

[0068] The obtained crude 2,6-NDA (purity 98.0%) and anhydrous methanol were added to the esterification reactor. The mass ratio of 2,6-NDA to methanol was 1:7.5. Under the action of catalyst sulfuric acid (8% wt) , the esterification reaction was carried out at 170° C. and 2.4MPa (gauge pressure), and the reaction was carried out for 5 hours. After the reaction was completed, after cooling, washing with deionized water and suction filtration, the obtained yellow flaky crystal was crude 2,6-NDC, the yield was 98.0%, the purity was 95.0%, and the chromaticity was 120.

[0069] First, the crude 2,6-NDC in the feed storage tank is melted, and the feed is continuously pumped in the tower for continuous rectification. Each part of the rectification tower exposed to the air needs to be traced, and the trace temperature is 195 °C. The rectification is often carried out under reduced pressure, the operating pressure is 10 mbar, the temperature at the bottom of the column is 210-270 °C...

Embodiment 2

[0072] The obtained crude 2,6-NDA (purity 98.0%) and anhydrous methanol were added to the esterification reactor, the mass ratio of 2,6-NDA and methanol was 1:7.5, under the action of catalyst sulfuric acid (9% wt) , the esterification reaction was carried out at 160° C. and 2.2 MPa (gauge pressure) for 7 hours. After the reaction was completed, after cooling, washing with deionized water and suction filtration, the obtained yellow flaky crystal was crude 2,6-NDC, the yield was 97.0%, the purity was 95.0%, and the chromaticity was 120.

[0073] First, the crude 2,6-NDC in the feed storage tank is melted, and the feed is continuously pumped in the tower for continuous rectification. Each part of the rectification tower exposed to the air needs to be traced, and the trace temperature is 200°C. The rectification is often carried out under reduced pressure, the operating pressure is 12 mbar, the temperature at the bottom of the column is 210-270 °C, and the theoretical plate numbe...

Embodiment 3

[0076] The obtained crude 2,6-NDA (purity 98.0%) and anhydrous methanol were added to the esterification reactor. The mass ratio of 2,6-NDA to methanol was 1:7.5. Under the action of catalyst sulfuric acid (8% wt) , the esterification reaction was carried out at 160° C. and 2.2 MPa (gauge pressure) for 7 hours. After the reaction was completed, after cooling, washing with deionized water and suction filtration, the obtained yellow flaky crystal was crude 2,6-NDC, the yield was 97.0%, the purity was 95.0%, and the chromaticity was 120.

[0077] First, the crude 2,6-NDC in the feed storage tank is melted, and the feed is continuously pumped in the tower for continuous rectification. Each part of the rectification tower exposed to the air needs to be traced, and the trace temperature is 200°C. The rectification is often carried out under reduced pressure, the operating pressure is 15 mbar, the temperature at the bottom of the column is 210-270 °C, and the theoretical plate number...

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Abstract

The invention provides a method for continuously refining dimethyl 2, 6-naphthalate, which comprises the following steps of: melting crude dimethyl 2, 6-naphthalate, and continuously rectifying in a rectifying tower to obtain molten dimethyl 2, 6-naphthalate; the method comprises the following steps: adding a solvent into a reaction kettle, heating to boil, introducing molten dimethyl 2, 6-naphthalate into the reaction kettle, dissolving the molten dimethyl 2, 6-naphthalate with the solvent, heating to boil, carrying out suction filtration for the first time, and arranging an adsorption filtration device at a discharge port of the reaction kettle; liquid obtained after first suction filtration flows into a double-layer suction filtration device to be subjected to second suction filtration, recrystallized dimethyl 2, 6-naphthalate is obtained, and heat tracing heat preservation devices are additionally arranged on the rectifying tower, the reaction kettle and the double-layer suction filtration device. According to the scheme, the rectification and recrystallization processes are adopted to continuously refine the 2, 6-NDC, and the extracted 2, 6-NDC in a molten state directly enters the recrystallization process without being cooled and condensed into blocks, so that the operation efficiency is improved, the extracted 2, 6-NDC is good in color, the yield can reach 92%, and the purity can reach 99.95% or above.

Description

technical field [0001] The invention relates to the field of new coal chemical materials, in particular to a method for continuously refining dimethyl 2,6-naphthalenedicarboxylate. Background technique [0002] my country's coal reserves are abundant. In today's increasingly tight energy environment, as a measure to increase the comprehensive utilization of heavy components in coal, petroleum and other energy sources, it is of great significance to develop a high value-added route for naphthalene. Dimethyl 2,6 naphthalate (NDC) is a key intermediate for some high-end specialty polyesters, and its main purpose is to synthesize polyethylene 2,6 naphthalate (PEN). PEN material is an emerging functional polymer resin material with superior performance, mainly composed of 2,6 naphthalene dicarboxylic acid (2,6-NDA) or 2,6-NDC and ethylene glycol esterification or transesterification and then polycondensation. Compared with the widely used polyethylene terephthalate (PET) and pol...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C67/48C07C67/52C07C67/54C07C67/56C07C69/76
CPCC07C67/48C07C67/52C07C67/54C07C67/56C07C69/76
Inventor 毛学锋李恒钟金龙张笑然李军芳胡发亭王通
Owner CCTEG CHINA COAL RES INST
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