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Purifying method for 1,4-cyclohexanedimethanol

A technology of cyclohexanedimethanol and purification method, which is applied in the field of reducing saponification value during rectification, can solve the problems of reducing product yield, affecting economic benefits, restricting the development of downstream products, etc., and achieve the effect of improving product quality

Inactive Publication Date: 2016-07-06
KAILING CHEM ZHANGJIAGANG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The crude product of 1,4-cyclohexanedimethanol obtained by the current process can be obtained by rectification with a purity >99.9%, but at this time the saponification value of the product is relatively high, greater than 0.60mgKOH / g, which limits the development of its downstream products
In the existing purification process, in order to reduce the saponification value of the product, the method of increasing the number of plates is often increased by increasing the tower height, but this method often reduces the product yield and affects economic benefits

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0016] Put 1t of crude product of 1,4-cyclohexanedimethanol in the distillation tower kettle, adopt a rectification tower with a tower height of 15m and a tower diameter of 0.8m, raise the temperature of the rectification tower, and turn on the vacuum pump to make the vacuum degree of the tower reach -0.095~ -1MPa, the temperature at the bottom of the tower is 230°C, when the temperature at the top of the tower reaches 200°C, start to collect 1,4-cyclohexanedimethanol into the finished product tank, when the temperature at the top of the tower exceeds 205°C, stop the rectification, and get the product 0.945t , The yield is 94.5%. After testing, the product has a purity of 99.8%, a saponification value of 0.38 mgKOH / g, and a moisture content of 0.06%.

example 2

[0018] Put 1t of crude product of 1,4-cyclohexanedimethanol into the distillation tower kettle, adopt a rectification tower with a tower height of 22m and a tower diameter of 0.8m, raise the temperature of the rectification tower, and turn on the vacuum pump to make the vacuum degree of the tower reach -0.095~ -1MPa, the temperature at the bottom of the tower is 230°C, when the temperature at the top of the tower reaches 200°C, start to collect 1,4-cyclohexanedimethanol into the finished product tank, when the temperature at the top of the tower exceeds 205°C, stop the rectification to obtain the product 0.805t , The yield is 80.5%. After testing, the product has a purity of 99.9%, a saponification value of 0.19 mgKOH / g, and a moisture content of 0.06%.

example 3

[0020] Put 1t of crude product 1,4-cyclohexanedimethanol into the distillation column kettle, add 0.96kg of NaOH solid (the molar ratio of alkali to ester impurities = 1:1), and use a rectification system with a tower height of 15m and a tower diameter of 0.8m Tower, heat up the rectification tower, turn on the vacuum pump to make the vacuum degree of the tower reach -0.095~-1MPa, the temperature at the bottom of the tower is 240°C, when the temperature at the top of the tower reaches 195°C, start to collect 1,4-cyclohexanedimethanol into the finished product tank, when the tower top temperature exceeds 205°C, the rectification is stopped to obtain a product of 0.938t with a yield of 93.8%. After testing, the product has a purity of 99.8%, a saponification value of 0.37mgKOH / g, and a moisture content of 0.05%.

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Abstract

The invention discloses a purifying method for 1,4-cyclohexanedimethanol.The purifying method comprises the following steps that crude 1,4-cyclohexanedimethanol and sodium hydroxide are added in a rectifying column bottom; rectifying starts to be performed under the vacuum condition, the rectifying column bottom temperature is 220 DEG C-240 DEG C, and when the column top temperature reaches 190 DEG C-205 DEG C, fractions start to be collected; when the column top temperature exceeds 205 DEG C, rectifying is stopped.According to 1,4-cyclohexanedimethanol obtained through the purifying method, the saponification value of the product can be greatly decreased.

Description

technical field [0001] The invention relates to a rectification method, in particular to a method for reducing saponification value during rectification. Background technique [0002] 1,4-Cyclohexanedimethanol is mainly used in the production of various polyesters and copolyesters such as PETG, SPCT, PCTG and PCTA. 1,4-Cyclohexanedimethanol is esterified with terephthalic acid, which has the characteristics of dicarboxylic acid, and is used to produce polyester fiber after polycondensation. It has the characteristics of low relative density, high melting point, and good electrical properties; it adopts 1,4-cyclohexanedimethanol copolymerized modified polyethylene terephthalate resin, the crystallization rate of the product is slow, but also has good processing and physical properties, 1,4-cyclohexanedimethanol The largest use of methanol is the production of PETG (glycol-modified PET resin), which is used in the production of thermoformed food packaging containers, bottles ...

Claims

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Application Information

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IPC IPC(8): C07C29/80C07C31/27
CPCC07C29/80C07C31/276
Inventor 杨俊峰唐华友吕耀武
Owner KAILING CHEM ZHANGJIAGANG CO LTD