1. Structure and Composition:

Pore Size: The "3A" designation refers to its pore diameter of 3 angstroms (0.3 nm), achieved by exchanging sodium ions in zeolite A with larger potassium ions, reducing the pore size from ~4 A to 3 A.

Chemical Formula: Typically represented as K₁₂[(AlO₂)₁₂(SiO₂)₁₂]·xH₂O, where potassium ions occupy cationic sites in the aluminosilicate framework.

2. Key Properties:

Selectivity: Adsorbs molecules smaller than 3 A, such as water (2.6 A), while excluding larger molecules (e.g., hydrocarbons, CO₂).

High Adsorption Capacity: Effective for removing moisture from gases and liquids without interfering with larger components.

3. Applications:

Gas Drying: Used in natural gas processing, air compression systems, and refrigeration circuits to prevent moisture-related issues (e.g., ice formation, corrosion).

Electronics Manufacturing: Dries solvents, gases, and cleanroom environments to avoid contamination during semiconductor production.

Plastics Industry: Dries resin pellets before extrusion to prevent hydrolysis and product defects.

Static Applications: Suitable for non-continuous processes where scheduled regeneration is feasible.

4. Regeneration:

Thermal Process: Heated to 200–300°C to desorb water, restoring capacity. Often uses hot inert gas (e.g., nitrogen) for purging.

Dual-Bed Systems: Employed in continuous processes to allow alternating adsorption and regeneration.

5. Limitations:

Saturation Risk: Requires timely regeneration in high-humidity environments.

Size Exclusion: Ineffective for adsorbing molecules ≥3 A (e.g., CO₂, hydrocarbons).