CN-122029135-A - Method for recovering valuable substances from waste liquid

CN122029135ACN 122029135 ACN122029135 ACN 122029135ACN-122029135-A

Abstract

The present disclosure provides a method of recovering valuable substances from a waste liquid, comprising, in a treatment of the waste liquid generated during purification of a reaction product in a petrochemical process in which raw materials are reacted in the presence of a catalyst to prepare a reaction product, purifying the reaction product to collect the waste liquid containing unreacted raw materials, the catalyst, a material to be removed and water, and supplying the waste liquid to a valuable substance recovery tower, in which the waste liquid is distilled to recover an upper discharge stream containing the unreacted raw materials and the catalyst and cool a lower discharge stream containing the material to be removed and water, and supplying the cooled lower discharge stream from the valuable substance recovery tower to a layer separator to separate the stream into an aqueous layer and an organic layer, diverting and refluxing a part of the aqueous layer to an upper portion of the valuable substance recovery tower, and discharging the remaining aqueous layer.

Inventors

JIN XINGJUN
LI CHENGGUI
BAI JIXIU
LI MINXU
ZHAO CHENGZHI

Assignees

株式会社LG化学

Dates

Publication Date: 20260512
Application Date: 20250623
Priority Date: 20240912

Claims (12)

1. A method for recovering valuable substances from waste liquid, which comprises, in the treatment of waste liquid generated during purification of reaction products in a petrochemical process in which raw materials are reacted in the presence of a catalyst to produce reaction products, (S1) purifying the reaction product to collect a waste liquid containing unreacted raw materials, catalyst, material to be removed and water, and supplying the waste liquid to a valuable substance recovery column; (S2) distilling the waste liquid in the valuable material recovery column to recover an upper effluent stream comprising the unreacted feedstock and the catalyst and cooling a lower effluent stream comprising the material to be removed and water, and (S3) supplying cooled lower effluent stream from the valuable material recovery column to a layer separator to separate the stream into an aqueous layer and an organic layer, diverting and refluxing a portion of the aqueous layer to an upper portion of the valuable material recovery column, and discharging the remaining aqueous layer, Wherein the material to be removed comprises a water-miscible compound, and The water-miscible compounds include those compounds having a boiling point below that of water and a boiling point difference from the unreacted starting materials of from-10 ℃ to 10 ℃.
2. The method for recovering valuable substances from waste liquid according to claim 1, wherein the waste liquid supplied to the valuable substance recovery column contains 0.1 to 10% by weight of the unreacted raw material, 0.1 to 10% by weight of the catalyst, 40 to 75% by weight of the material to be removed, and 20 to 50% by weight of water.
3. The method for recovering valuable substances from waste liquid according to claim 1, wherein (S1) comprises: Purifying the reaction product to collect a first waste liquid comprising the unreacted raw material, the catalyst, the material to be removed and water, and supplying the first waste liquid to a volatile organic compound separation column; Distilling the first effluent in the VOC separation column to obtain a second effluent comprising the unreacted feedstock, the catalyst, the material to be removed and water as an upper effluent stream, and a wastewater comprising water as a lower effluent stream, and The second waste liquid is supplied to the valuable substance recovery tower.
4. A method of recovering valuable substances from a waste liquid according to claim 3, wherein the first waste liquid contains 0.05 to 5% by weight of the unreacted raw material, 0.05 to 5% by weight of the catalyst, 1 to 10% by weight of the material to be removed, and the remaining amount of water, relative to the total flow rate.
5. A method of recovering valuable substances from a waste stream according to claim 3, wherein the second waste stream comprises 0.1 to 10 wt.% of the unreacted starting material, 0.1 to 10 wt.% of the catalyst, 40 to 75 wt.% of the material to be removed and 20 to 50 wt.% of vaporized water, relative to the total weight flow.
6. The method for recovering valuable substances from waste liquid according to claim 1, wherein a flow rate ratio of a flow which is branched from the water layer and refluxed to an upper portion of the valuable substance recovery column is 80 to 95% by weight based on 100% by weight of a total flow rate of the water layer separated in the layer separator.
7. The method of recovering valuable substances from waste liquid according to claim 1, wherein the temperature of the lower effluent stream from the valuable substance recovery column before cooling is 65 ℃ to 100 ℃.
8. The method for recovering valuable substances from waste liquid according to claim 1, wherein the temperature of a portion of the stream refluxed to the upper portion of the valuable substance recovery column is 25 ℃ to 50 ℃.
9. The method for recovering valuable substances from waste liquid according to claim 1, Wherein the raw materials comprise isobutyraldehyde and formaldehyde, The unreacted starting materials include isobutyraldehyde, The catalyst comprises triethylamine.
10. The method for recovering a valuable substance from a waste stream according to claim 1, wherein the water-miscible compound comprises methanol.
11. The method for recovering valuable substances from waste liquid according to claim 1, wherein the upper discharge stream from the valuable substance recovery column containing the unreacted raw material and the catalyst recovered in (S2) is reused in the petrochemical process.
12. The method for recovering valuable substances from waste liquid according to claim 1, wherein the petrochemical process is a neopentyl glycol production process.

Description

Method for recovering valuable substances from waste liquid Technical Field Cross Reference to Related Applications The present application claims the priority benefit of korean patent application No. 10-2024-0125262 filed on 9/12 of 2024, the entire contents of which are incorporated herein as part of the specification. Technical Field The present application relates to a method of recovering valuable substances from waste liquid, and more particularly to a method of recovering organic materials other than materials to be removed as valuable substances from waste liquid produced in petrochemical processes. Background In conventional petrochemical processes, raw materials are reacted in the presence of a catalyst to produce a reaction product, and the reaction product is purified to produce a final product. Here, in the purification process, water and impurities contained in the raw materials, organic materials generated by the reaction of byproducts in the reaction process, and the like are separated and treated as waste liquid. As a representative petrochemical process, neopentyl glycol (NPG) can be produced by conducting an aldol condensation reaction of Isobutyraldehyde (IBAL) and Formaldehyde (FA) in the presence of a catalyst to form Hydroxypivalaldehyde (HPA) and conducting a hydrogenation reaction of hydroxypivalaldehyde. However, since formaldehyde is used in an aqueous solution state to ensure reactivity and fluidity, it contains a large amount of water, which is treated as wastewater after aldol condensation reaction. In addition, since formaldehyde contains a small amount of methanol, methanol is continuously introduced during the NPG production process, and isobutanol (i-BuOH) is produced as a byproduct of aldol condensation reaction. The alcohol is treated as waste oil after aldol condensation reaction. Here, unreacted raw materials and catalyst which have not been separated in the purification process are introduced into the waste liquid containing waste water and waste oil, but since their boiling points are close to those of methanol which is one of the materials to be removed, it is difficult to further recover valuable substances such as unreacted raw materials and catalyst from the waste liquid. In addition, the catalyst contained in the waste liquid and discarded may cause environmental pollution problems. Therefore, a method that is environmentally friendly and can further improve economic feasibility by further recovering valuable substances from waste liquid that is discarded should be introduced. Disclosure of Invention Technical problem In order to solve the problems mentioned in the background art, an object of the present disclosure is to provide a method of recovering valuable substances from waste liquid, which can effectively remove materials to be removed when recovering unreacted raw materials and catalyst from waste liquid. However, the objects to be solved in the present disclosure are not limited to the above objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description. Technical proposal In one general aspect, a method of recovering valuable substances from a waste liquid includes purifying a reaction product to collect a waste liquid including unreacted raw materials, a catalyst, materials to be removed, and water and supplying the waste liquid to a valuable substance recovery tower, distilling the waste liquid to recover an upper discharge stream including the unreacted raw materials and the catalyst and cooling a lower discharge stream including the materials to be removed and water, and supplying the cooled lower discharge stream from the valuable substance recovery tower to a layer separator to separate the stream into an aqueous layer and an organic layer, diverting and refluxing a portion of the aqueous layer to an upper portion of the valuable substance recovery tower, and discharging a remaining aqueous layer in a treatment of the waste liquid generated during purification of the reaction product in a petrochemical process in which the raw materials are reacted in the presence of the catalyst to prepare the reaction product. Advantageous effects According to the method of recovering valuable substances from waste liquid of the present disclosure, when waste liquid containing unreacted raw materials, catalyst, material to be removed and water is supplied to a valuable substance recovery tower and distilled, a part of water discharged to the lower part of the valuable substance recovery tower is supplied to the valuable substance recovery tower, thereby separating valuable substances (unreacted raw materials and catalyst) having similar boiling points and material to be removed by a difference in solubility in water. In addition, unreacted raw materials and catalyst separated from the valuable substances recovery column can be recycled to the petrochemical process and reused as raw materials. Therefo