Method for purifying isopropanol from isopropanol waste liquid

Abstract

The invention discloses a method for purifying isopropanol from isopropanol waste liquid. The method comprises the following steps: (1) primary rectification; (2) solid alkali dehydration; and (3) secondary rectification. Compared with a membrane separation method, the method provided by the invention has the advantages that membrane equipment does not need to be introduced, and the cost is greatly reduced; compared with an azeotropic distillation method, the method has the advantages that energy consumption is effectively reduced, an entrainer is not needed, expenditure is reduced, the problems of personal harm and environmental pollution do not exist in production operation, on the basis of existing distillation equipment, isopropanol is purified to the maximum extent in a simplest and most convenient mode to increase income, loss is low, and the method is suitable for industrial production. Other equipment does not need to be purchased, expenditure is reduced, and harm and pollution are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of isopropanol purification, and in particular to a method for purifying isopropanol from isopropanol waste liquid. Background Art

[0002] Isopropyl alcohol, also known as 2-propanol, is a common secondary alcohol. It is a colorless liquid known for its volatility and low boiling point (about 82.6°C). Its melting point is -89.5°C. Isopropyl alcohol is completely miscible in most solvents such as water, ethanol and chloroform, and can dissolve a variety of non-polar compounds, showing its characteristics as a multifunctional solvent. Isopropyl alcohol is an important chemical raw material and solvent, mainly used in pharmaceuticals, cosmetics, plastics, fragrances, coatings, etc. It can also be used as a chromatographic analysis standard and is used in the electronics industry and the oil and fat industry. In the recovery process of isopropyl alcohol waste liquid, it is necessary to separate isopropyl alcohol from water. The traditional separation of isopropyl alcohol-water azeotropes adopts azeotropic distillation and membrane separation. The azeotropic distillation method usually uses benzene as an azeotropic agent. This process has a large energy consumption, and the azeotropic agent has personal hazards and environmental pollution problems in production operations. The membrane separation method requires the introduction of membrane equipment, which is relatively costly. Therefore, there is an urgent need for a method for purifying isopropyl alcohol from isopropyl alcohol waste liquid that is low in energy consumption, low in cost, harmless, pollution-free and simple. Summary of the invention

[0003] The invention aims to provide a method for purifying isopropyl alcohol from isopropyl alcohol waste liquid. The method is simple and easy to operate, effectively saves and reduces energy consumption, does not require an entrainer, is harmless, pollution-free and reduces costs.

[0004] In order to solve the above problems, the present invention provides the following technical solutions:

[0005] The present invention provides a method for purifying isopropanol from isopropanol waste liquid, comprising the following steps:

[0006] (1) Primary distillation;

[0007] (2) Solid alkali dehydration;

[0008] (3) Secondary distillation.

[0009] Furthermore, the specific steps of the primary distillation are as follows: subjecting the isopropanol waste liquid to binary azeotropic distillation, collecting the fraction at 81.5-84° C., and obtaining crude isopropanol.

[0010] Furthermore, the water content of the isopropanol waste liquid is 60wt%.

[0011] Furthermore, the specific steps of the solid alkali dehydration are as follows: the obtained crude isopropanol is put into a dehydration tank, solid sodium hydroxide is added, stirred, allowed to stand, and separated into layers, the upper layer is isopropanol, a milky white turbid liquid, the lower layer is a sodium hydroxide solution, a colorless transparent liquid, and the isopropanol in the upper layer is taken for standby use.

[0012] Furthermore, the amount of solid sodium hydroxide added is 20-23% of the mass of crude isopropanol.

[0013] Furthermore, the stirring speed is 150-200 r / min and the time is 2-4 h.

[0014] Furthermore, the specific steps of the secondary distillation are as follows: the isopropyl alcohol taken from the upper layer is pumped into a distillation kettle for distillation, and the fraction at 75-82.5° C. is collected to obtain colorless and transparent finished isopropyl alcohol.

[0015] The beneficial effects of the present invention are:

[0016] Compared with the membrane separation method, the method provided by the present invention does not need to introduce membrane equipment, which greatly reduces costs; compared with the azeotropic distillation method, it effectively saves and reduces energy consumption and does not need an azeotropic agent, which reduces expenses, and there is no problem of personal harm and environmental pollution in production operations. The present invention increases profits by purifying isopropanol to the greatest extent in the simplest way on the basis of existing distillation equipment, and has less loss, does not need to purchase other equipment, reduces expenses, is harmless, and does not pollute. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with specific embodiments.

[0018] It should be noted that these embodiments are only used to illustrate the present invention rather than to limit the present invention. Simple improvements to the method based on the concept of the present invention all fall within the scope of protection claimed by the present invention.

[0019] Example 1

[0020] A method for purifying isopropanol from isopropanol waste liquid comprises the following steps:

[0021] (1) Primary distillation

[0022] The isopropanol waste liquid with a water content of 60 wt% is subjected to binary azeotropic distillation, and a fraction at 81.5-84° C. is collected to obtain crude isopropanol;

[0023] (2) Solid alkali dehydration

[0024] The obtained crude isopropanol was put into a dehydration tank, solid sodium hydroxide equivalent to 20% of the mass of the crude isopropanol was added, and the mixture was stirred at a speed of 150 r / min for 4 hours, and then allowed to stand for stratification. The upper layer was isopropanol, a milky white turbid liquid, and the lower layer was a sodium hydroxide solution, a colorless transparent liquid. The isopropanol in the upper layer was taken for later use;

[0025] (3) Secondary distillation

[0026] The isopropyl alcohol obtained from the upper layer is pumped into a distillation kettle for rectification, and the fraction at 75-82.5° C. is collected to obtain a colorless and transparent finished isopropyl alcohol.

[0027] Example 2

[0028] A method for purifying isopropanol from isopropanol waste liquid comprises the following steps:

[0029] (1) Primary distillation

[0030] The isopropanol waste liquid with a water content of 60 wt% is subjected to binary azeotropic distillation, and a fraction at 81.5-84° C. is collected to obtain crude isopropanol;

[0031] (2) Solid alkali dehydration

[0032] The obtained crude isopropanol was put into a dehydration tank, solid sodium hydroxide equivalent to 21% of the mass of the crude isopropanol was added, and the mixture was stirred at a speed of 180 r / min for 3 hours, and then allowed to stand for stratification. The upper layer was isopropanol, a milky white turbid liquid, and the lower layer was a sodium hydroxide solution, a colorless transparent liquid. The isopropanol in the upper layer was taken for later use;

[0033] (3) Secondary distillation

[0034] The isopropyl alcohol obtained from the upper layer is pumped into a distillation kettle for rectification, and the fraction at 75-82.5° C. is collected to obtain a colorless and transparent finished isopropyl alcohol.

[0035] Example 3

[0036] A method for purifying isopropanol from isopropanol waste liquid comprises the following steps:

[0037] (1) Primary distillation

[0038] The isopropanol waste liquid with a water content of 60 wt% is subjected to binary azeotropic distillation, and a fraction at 81.5-84° C. is collected to obtain crude isopropanol;

[0039] (2) Solid alkali dehydration

[0040] The obtained crude isopropanol was put into a dehydration tank, solid sodium hydroxide equivalent to 23% of the mass of the crude isopropanol was added, and the mixture was stirred at a speed of 200 r / min for 2 hours, and then allowed to stand for stratification. The upper layer was isopropanol, a milky white turbid liquid, and the lower layer was a sodium hydroxide solution, a colorless transparent liquid. The isopropanol in the upper layer was taken for later use;

[0041] (3) Secondary distillation

[0042] The isopropyl alcohol obtained from the upper layer is pumped into a distillation kettle for rectification, and the fraction at 75-82.5° C. is collected to obtain a colorless and transparent finished isopropyl alcohol.

[0043] The water content and yield of isopropanol obtained by the methods provided in Examples 1-3 are shown in the following table.

[0044] Moisture content (W / W%) Yield (W / W%) Example 1 3.84 35.1 Example 2 3.69 36.7 Example 3 3.76 36.0

[0045] As can be seen from the above table, the method for purifying isopropyl alcohol from isopropyl alcohol waste liquid provided by the present invention can significantly reduce the water content of isopropyl alcohol, and the water content of the obtained isopropyl alcohol is less than 4%, and the yield is greater than 35%, which can meet the use requirements. The present invention increases the income by purifying isopropyl alcohol to the greatest extent in the simplest way on the basis of the existing distillation equipment, and has less loss, no need to purchase other equipment, reduces expenses, is harmless, and is pollution-free.

[0046] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for purifying isopropanol from isopropanol waste liquid, characterized in that, The following steps are involved: (1) Primary distillation; (2) Solid alkali dehydration; (3) Secondary distillation.

2. A method for purifying isopropanol from isopropanol waste liquid according to claim 1, characterized in that: The specific steps of the primary distillation are as follows: subjecting the isopropanol waste liquid to binary azeotropic distillation, collecting the fraction at 81.5-84° C., and obtaining crude isopropanol.

3. A method for purifying isopropanol from isopropanol waste liquid according to claim 2, characterized in that: The water content of the isopropanol waste liquid is 60 wt %.

4. A method for purifying isopropanol from isopropanol waste liquid according to claim 2, characterized in that: The specific steps of the solid alkali dehydration are as follows: the obtained crude isopropanol is put into a dehydration tank, solid sodium hydroxide is added, stirred, allowed to stand, and separated into layers, wherein the upper layer is isopropanol, a milky white turbid liquid, and the lower layer is a sodium hydroxide solution, a colorless transparent liquid, and the isopropanol in the upper layer is taken for standby use.

5. A method for purifying isopropanol from isopropanol waste liquid according to claim 4, characterized in that: The amount of solid sodium hydroxide added is 20-23% of the mass of crude isopropanol.

6. A method for purifying isopropanol from isopropanol waste liquid according to claim 4, characterized in that: The stirring speed is 150-200 r / min and the time is 2-4 h.

7. A method for purifying isopropanol from isopropanol waste liquid according to claim 4, characterized in that: The specific steps of the secondary distillation are as follows: the isopropyl alcohol taken from the upper layer is pumped into a distillation kettle for distillation, and the fraction at 75-82.5° C. is collected to obtain a colorless and transparent finished isopropyl alcohol.