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CN-121990876-A - Method for recovering tertiary butanol from toluene-and tertiary butanol-containing waste liquid

CN121990876ACN 121990876 ACN121990876 ACN 121990876ACN-121990876-A

Abstract

The invention relates to the technical field of multicomponent separation, and discloses a method for recovering tertiary butanol from toluene-tertiary butanol-containing waste liquid, which comprises (1) carrying out first rectification on the toluene-tertiary butanol-containing waste liquid to obtain a first gas phase material and water; the method comprises the steps of (1) condensing a first gas-phase material, then carrying out second rectification to obtain a second gas-phase material, wherein the operation temperature of the top of the first rectification is 3-5 ℃ higher than that of the top of the second rectification, the operation temperature of the bottom of the first rectification is 14-20 ℃ higher than that of the bottom of the second rectification, and (3) separating oil from water after condensing the second gas-phase material to obtain an oil phase and a water phase, returning the oil phase to the step (2) for second rectification again, and returning the water phase to the step (1) for first rectification again. The method can separate the tertiary butanol waste liquid containing different concentrations without introducing new components, and has the advantages of high separation recovery rate, high product purity and simple and convenient steps.

Inventors

  • XU BOHANG
  • WANG XIAOQIAN
  • YANG HONGXIA
  • ZHANG GUANGCHENG
  • WANG DING
  • HUANG DAN

Assignees

  • 中化环境科技工程有限公司

Dates

Publication Date
20260508
Application Date
20251218

Claims (10)

  1. 1. A process for recovering t-butanol from a toluene-and t-butanol-containing waste stream, the process comprising: (1) Carrying out first rectification on waste liquid containing toluene and tertiary butanol to obtain a first gas phase material and a first product, wherein the mass fraction of tertiary butanol in the waste liquid is 2.5-86 wt% based on the total mass of the waste liquid; (2) Condensing the first gas-phase material and then carrying out second rectification to obtain a second gas-phase material, wherein the operation temperature of the top of the first rectification is 2-5 ℃ higher than that of the top of the second rectification, and the operation temperature of the bottom of the first rectification is 14-20 ℃ higher than that of the bottom of the second rectification; (3) Condensing the second gas phase material, performing oil-water separation to obtain an oil phase and a water phase, returning the oil phase to the step (2) for performing second rectification again to obtain tertiary butanol, and returning the water phase to the step (1) for performing first rectification again.
  2. 2. The method of claim 1, wherein the mass fraction of t-butanol in the waste stream is 4.5wt% to 16wt% based on the total mass of the waste stream.
  3. 3. The method of claim 1, wherein the mass ratio of tertiary butanol to toluene in the waste stream is greater than 12:1.
  4. 4. A method according to claim 3, wherein the mass ratio of tertiary butanol to toluene in the waste stream is greater than 50:1.
  5. 5. The method according to claim 1, wherein in the step (1), the first rectification is performed in a first rectification column, a feed inlet of the first rectification column is positioned at an upper middle portion of the first rectification column, a theoretical plate number of the first rectification column is 10-60, a reflux ratio is 1-15, an operation pressure of the first rectification column is 0.09-0.2MPa, an operation temperature of a column top is 76-85 ℃, and an operation temperature of a column bottom is 95-100 ℃.
  6. 6. The process according to claim 5, wherein in the step (1), the theoretical plate number of the first rectifying column is 15 to 30 and the reflux ratio is 1.5 to 5.
  7. 7. The method according to claim 1, wherein in the step (2), the rectification is performed in a second rectification column, a feed inlet of the second rectification column is positioned at the upper middle part of the second rectification column, the theoretical plate number of the second rectification column is 10-60, the reflux ratio is 1-15, the operating pressure of the second rectification column is 0.09-0.2MPa, the operating temperature of the column top is 72-80 ℃, and the operating temperature of the column bottom is 78-85 ℃.
  8. 8. The process according to claim 7, wherein in the step (2), the theoretical plate number of the second rectification column is 15 to 30 and the reflux ratio is 1.5 to 5.
  9. 9. The method according to claim 1, wherein in the step (3), the oil-water separation is performed in an oil-water separator having an operating temperature of 40-60 ℃, an operating pressure of 0.09-0.2MPa, and a separation time of 5-120 minutes.
  10. 10. The method according to claim 9, wherein in the step (3), the oil-water separation is performed in an oil-water separator having an operating temperature of 45 to 55 ℃, an operating pressure of 0.1MPa, and a separation time of 30 to 60 minutes.

Description

Method for recovering tertiary butanol from toluene-and tertiary butanol-containing waste liquid Technical Field The invention relates to the technical field of multicomponent separation, in particular to a method for recovering tertiary butanol from toluene-tertiary butanol-containing waste liquid. Background Tertiary butanol is colorless crystals, and is a weak polar small molecular organic matter. The water-based organic light-emitting material is colorless volatile liquid in the presence of a small amount of water, has a camphor-like smell, is widely applied, and is mainly used as a gasoline additive, a solvent and an organic synthetic raw material. Under normal pressure, tert-butanol and water form an azeotrope system, however, for separation and purification of the azeotrope system, methods including azeotropic distillation, extractive distillation, adsorptive distillation, pervaporation, adsorption method, and the like have been reported. The methods have advantages and disadvantages, and the actual application needs to be comprehensively selected according to factors such as separation requirements, energy consumption cost, environmental protection indexes and the like. At present, most of upstream raw materials of the conventional azeotropic distillation process are high-concentration tertiary butanol aqueous solution prepared by an isobutene hydration method, and the feed composition of the upstream raw materials is close to the tertiary butanol-water azeotropic composition, so that the process can be directly applied. However, aiming at the common toluene-and-tertiary butanol-containing waste liquid in industrial scenes, the process has the remarkable limitations that on one hand, cyclohexane is required to be introduced as an entrainer to break azeotropic balance in the existing process, so that not only can new external components be introduced in the process to cause poor treatment effect on target waste liquid, but also new impurities can be additionally introduced to increase subsequent treatment burden, and on the other hand, if the process is adopted to separate tertiary butanol-water mixture, the tertiary butanol concentration is required to be pre-extracted to be close to azeotropic composition through a dehydration tower, and then the entrainer (cyclohexane) is added, the azeotropic distillation tower is used for separation, the recovery tower is used for purification and other multi-step operations, so that the investment cost of the whole process equipment is high, the whole process energy consumption is large, and the economical efficiency and the practicability are not ideal. Disclosure of Invention The invention aims to solve the problems of complicated separation method and poor separation effect of waste liquid containing toluene and tertiary butanol in the prior art, and provides a method for recovering tertiary butanol from the waste liquid containing toluene and tertiary butanol. In order to achieve the above object, the present invention provides a method for recovering t-butanol from a toluene-and t-butanol-containing waste liquid, comprising: (1) Carrying out first rectification on waste liquid containing toluene and tertiary butanol to obtain a first gas phase material and a first product, wherein the mass fraction of tertiary butanol in the waste liquid is 2.5-86 wt% based on the total mass of the waste liquid; (2) Condensing the first gas-phase material and then carrying out second rectification to obtain a second gas-phase material, wherein the operation temperature of the top of the first rectification is 2-5 ℃ higher than that of the top of the second rectification, and the operation temperature of the bottom of the first rectification is 14-20 ℃ higher than that of the bottom of the second rectification; (3) Condensing the second gas phase material, performing oil-water separation to obtain an oil phase and a water phase, returning the oil phase to the step (2) for performing second rectification again to obtain tertiary butanol, and returning the water phase to the step (1) for performing first rectification again. Through the technical scheme, the invention has the following advantages: (1) The method can efficiently separate the mixed solution containing the tertiary butanol with different concentrations (the feeding concentration of the tertiary butanol can be as low as 2.5wt percent), and the separation recovery rate is between 94 percent and 99.99 percent. (2) The method can realize the separation of tertiary butanol, toluene and water without introducing new components (impurities), and the purity of the separated product is higher, and the mass fraction of the tertiary butanol can reach more than 90 wt%. (3) The method can complete separation by only two rectifying towers, and has simple steps, less equipment investment and energy consumption. Detailed Description The endpoints and any values of the ranges disclosed herein are not limited to the precise range