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Method for purifying C4 to C6 dibasic acid monomers from adipic acid byproduct mixed dibasic acid

A technology for mixing dibasic acid and dibasic acid dimethyl ester, which is applied in the field of purifying C4-C6 dibasic acid monomers, can solve the problems of high separation and purification operation cost, incomplete hydrolysis reaction, consumption of a large amount of magnesium oxide, etc. The effect of improving reaction efficiency and saving reaction steps

Active Publication Date: 2017-07-18
SHANGHAI HUAFON NEW MATERIAL R&D TECH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that succinic acid and adipic acid still have a certain solubility at 15-20°C, resulting in a low yield, and this method needs to consume a large amount of magnesium oxide and sulfuric acid, and the composite solvent used for extraction is in use. there will be losses
In addition, this process requires a large amount of catalyst, and the catalyst needs to be regenerated every time the raw material is replaced. The process is complicated, the catalyst is easily broken, and the hydrolysis reaction is incomplete, which limits the commercial application of this process.
[0012] In summary, the existing patent literature and journal literature report the method of using physical methods to purify the C4-C6 dibasic acids in the by-product mixed dibasic acids of adipic acid, which has the problems of poor product quality and low yield; In the process of esterification and hydrolysis by chemical methods, the solid catalyst used for esterification is easy to block pores and deactivate, the amount of resin catalyst used for hydrolysis is large, the hydrolysis is not complete, the product purity and yield are low, the single-pot reaction efficiency is low, and the reaction time is too long Long-term problems, high operating costs for separation and purification

Method used

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  • Method for purifying C4 to C6 dibasic acid monomers from adipic acid byproduct mixed dibasic acid
  • Method for purifying C4 to C6 dibasic acid monomers from adipic acid byproduct mixed dibasic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] Add 2000g of DBA and 2000g of methanol melted at 120°C to a 5L reaction kettle, add 1.23g of concentrated nitric acid, and perform esterification at 65°C for 24h.

[0056] Stand to separate layers, take the supernatant and distill:

[0057] First distill methanol and water: gradually heat up to 100°C under normal pressure, then gradually reduce the pressure to 30KPa, distill until no liquid comes out of the top of the tower, and distill 1630g of methanol and water;

[0058] Afterwards, the pressure was gradually reduced to 1KPa, and the distillate at the top temperature of 60-95°C was collected to obtain 1830g of dibasic acid dimethyl ester mixture, the main components of which were as follows:

[0059] Dimethyl succinate 23.98wt%,

[0060] Dimethyl glutarate 62.25wt%,

[0061] Dimethyl adipate 13.77wt%.

[0062] 420g remained at the bottom of the kettle.

Embodiment 2

[0064] 2285g of DBA slices and 1715g of methanol were added to a 5L reaction kettle, 6.15g of concentrated nitric acid was added, and esterified at 90°C for 16h.

[0065] Stand to separate layers, take the supernatant and distill:

[0066] First distill methanol and water: firstly under normal pressure, gradually raise the temperature to 100°C, then gradually reduce the pressure to 30KPa, distill until no liquid comes out from the top of the tower, distill out 1280g of methanol and water.

[0067] Afterwards, the pressure was gradually reduced to 5KPa, and the fraction at the top temperature of 85-125°C was collected to obtain 2050g of dibasic acid dimethyl ester mixture, the main components of which were as follows:

[0068] Dimethyl succinate 24.30wt%,

[0069] Dimethyl glutarate 60.05wt%,

[0070] Dimethyl adipate 15.65 wt%.

[0071] 600g remained at the bottom of the kettle.

Embodiment 3

[0073]Add 1600g of DBA slices and 6400g of methanol into a 10L reaction kettle, add 24.6g of concentrated nitric acid, and esterify at 72°C for 8h.

[0074] Stand to separate layers, take the supernatant and distill:

[0075] First distill methanol and water: firstly under normal pressure, gradually raise the temperature to 100°C, then gradually reduce the pressure to 30KPa, distill until no liquid comes out from the top of the tower, distill out 6050g of methanol and water.

[0076] Afterwards, the pressure was gradually reduced to 10KPa, and the fraction at the top temperature of 100-145°C was collected to obtain 1500g of dibasic acid dimethyl ester mixture, the main components of which were as follows:

[0077] Dimethyl succinate 24.30wt%,

[0078] Dimethyl glutarate 62.98wt%,

[0079] Dimethyl adipate 12.72wt%.

[0080] 290g remained at the bottom of the kettle.

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Abstract

The invention discloses a method for purifying C4 to C6 dibasic acid monomers from an adipic acid byproduct mixed dibasic acid. The method disclosed by the invention comprises the following steps: firstly, carrying out esterification reaction on the adipic acid byproduct mixed dibasic acid and methanol at pre-set temperature in the presence of a catalyst; distilling and separating out mixed dibasic acid dimethyl ester; rectifying to obtain dimethyl succinate, dimethyl glutarate and dimethyl adipate; carrying out hydrolysis reaction on the dimethyl monomers in a rectifying reactor in the presence of a hydrolysis catalyst by two sections; at the first section of the reaction, controlling the conversion ratio of a hydrolysis ester group to be 80 percent to 95 percent and directly utilizing tower top methanol to esterify; at the second section of the reaction, controlling the conversion ratio of the hydrolysis ester group to 99.9 percent or more and directly utilizing a mixture of the tower top methanol and water to hydrolyze raw materials. According to the method disclosed by the invention, the conversion ratio of the ester group and the reaction efficiency are improved; no waste liquid is generated in a hydrolysis process so that the method is a green and environment-friendly production process.

Description

technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a method for purifying C4-C6 dibasic acid monomers from adipic acid by-product mixed dibasic acids. Background technique [0002] With the continuous development of polyurethane and nylon industries, the production capacity and product quality of adipic acid as the main raw material have been greatly improved. A certain amount of C is by-produced in the industrial production process of adipic acid 4～6 The output of mixed dibasic acid (also known as nylon acid, DBA for short) is about 3% to 5% of that of adipic acid. Due to different manufacturers and batches of products, the composition of DBA and the purity of products are also different. Generally, C 4～6 The total dibasic acid content in the mixed dibasic acid is 95%-97%, of which succinic acid (C4) accounts for 20-30wt%, glutaric acid (C5) accounts for 50-65wt%, adipic acid (C6) accounts for 10% ~20wt%, and copp...

Claims

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Application Information

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IPC IPC(8): C07C51/09C07C55/10C07C55/12C07C55/14
CPCC07C51/09C07C67/08C07C67/54C07C55/10C07C55/12C07C55/14C07C69/40C07C69/42C07C69/44
Inventor 张元华王艳辉王乾龙刘鑫张羿新唐丽华高冰马宁唐劲松
Owner SHANGHAI HUAFON NEW MATERIAL R&D TECH CO LTD
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