Application of molecular sieve: Purification of trace water in n-hexanol solvent

N-hexanol is a colorless and transparent liquid with a special aroma. Its molecular structure is CH3(CH2)5OH. It is used for organic solvents and organic synthesis raw materials, drug manufacturing and flavor preparation.

Preparation and impurity removal

N-hexanol is usually prepared by chemical synthesis and is widely used in industry due to its high efficiency and controllability. Hexane is converted into n-hexylaldehyde by oxidation reaction, and then n-hexylaldehyde is reduced to n-hexanol by hydrogenation reaction under the action of catalyst, or it is prepared by hexanoic acid catalytic hydrogenation reduction, etc.

Regardless of the preparation method, the obtained crude n-hexanol may contain impurities and further purification treatment is required.

About anhydrous purification treatment

In order to obtain anhydrous n-hexanol, the commonly used methods are:

1. Distillation: Using the difference between the boiling point of n-hexanol, which is about 157.88°C and the boiling point of other impurities, separation is carried out through a distillation tower to obtain n-hexanol with slightly higher purity.

2. Molecular sieve treatment: Using the adsorption properties of molecular sieves, trace water in n-hexanol is removed. This method can obtain anhydrous n-hexanol with extremely high purity.

Notes on the use of molecular sieves:

1. Select molecular sieves: First, you need to select a suitable molecular sieve. For removing water from n-hexanol, commonly used molecular sieve types include 3A and 4A, which have high adsorption capacity, especially for water molecules.

2. Build a system: According to experimental or production requirements, build a system including a n-hexanol storage tank, a molecular sieve adsorption column, a collection container, and necessary pipes and valves. Make sure all components are tightly connected and leak-free.

3. Fill the molecular sieve: Fill the molecular sieve evenly and tightly into the adsorption column to ensure its adsorption effect.

4. n-hexanol feeding: Slowly introduce n-hexanol into the adsorption column through a pipeline. During the inflow process, the flow rate should be controlled to avoid the contact time between n-hexanol and the molecular sieve being too short or too long, which affects the adsorption effect.

5. Adsorption process: When n-hexanol passes through the adsorption column, the trace amount of water in it will be adsorbed by the molecular sieve. According to the adsorption capacity of the molecular sieve and the water content in n-hexanol, the contact time between n-hexanol and the molecular sieve needs to be maintained for a period of time.

6. Collecting anhydrous n-hexanol: After adsorption by the molecular sieve, most of the water in the n-hexanol is removed, and anhydrous n-hexanol can be collected at this time.