The deep dehydration and drying of isopropanol solvent by molecular sieve requires a combination of the characteristics of molecular sieve and the physical and chemical properties of isopropanol. The following is a specific plan:

1. Molecular screening criteria

3A molecular sieve: with a pore size of about 0.3nm, it can only adsorb water molecules (with a diameter of about 0.28nm) and cannot adsorb isopropanol (with a molecular diameter of about 0.47nm). Suitable for drying small molecule alcohols such as ethanol and methanol, but ineffective for isopropanol.

4A molecular sieve: with a pore size of about 0.4nm, it can adsorb larger molecules such as water and isopropanol. Isopropanol molecules (0.47nm) can enter the pore channels of 4A molecular sieves to achieve deep drying.

2. Drying process parameters

Molecular sieve pretreatment: It needs to be activated at 250-300 ℃ for 3 hours to remove adsorbed moisture and impurities.

Dosage and processing time:

Industrial grade isopropanol (with a water content of ≥ 98%) can be treated with a 4A molecular sieve adsorption tower, with a molecular sieve dosage of 300L and a processing capacity of 0.5m ³/h, to obtain high-purity isopropanol with a water content of<100ppm.

Powdered 4A molecular sieve can be directly mixed and stirred with isopropanol, and separated by filtration after adsorption.

Regeneration method: The saturated 4A molecular sieve needs to be heated at 170-250 ℃ and purged with nitrogen to remove adsorbed water. After cooling, it can be recycled for use.

3. Operation precautions

Avoid azeotrope interference: Isopropanol forms an azeotrope with water (boiling point 82.3 ℃), which needs to be broken by molecular sieve adsorption instead of simple distillation.

Peroxide treatment: Isopropanol stored for a long time may contain peroxides, which need to be detected with starch potassium iodide reagent. If it appears blue, it needs to be removed by refluxing with stannous chloride.

Safe operation: Molecular sieves have good compatibility with isopropanol, but it is necessary to avoid open flames and high temperature environments to prevent organic solvent vapor explosions.