The purification stage in cryogenic air separation is critical. Its core task is to remove low-temperature condensable components (such as H₂O, CO₂, and hydrocarbons) from air using a combination of molecular sieves and activated alumina, ensuring the safe and stable operation of subsequent distillation columns.
If improperly purified air enters the distillation process, it may lead to column freezing or even damage the equipment, resulting in significant downtime and economic losses. Therefore, molecular sieves and activated alumina are essential in removing moisture, CO₂, and hydrocarbons that may freeze under cryogenic conditions.
Functions and Selection of Adsorbents:
Activated Alumina (Al₂O₃):
Main Function: Preferentially adsorbs moisture (static adsorption capacity up to 15–20%), protecting molecular sieves from steam poisoning.
Advantages: High mechanical strength and temperature resistance (regeneration at ~200–300°C), making it ideal for pre-adsorption layers.
Molecular Sieves (e.g., 13X, 5A):
Selective Adsorption:
● 13X: Efficient for CO₂ (pore size 10Å, suitable for CO₂ kinetic diameter of 3.3Å) and larger molecules like propane (C₃H₈).
● 5A: Designed for smaller hydrocarbons like acetylene (C₂H₂) to reduce LOX zone explosion risks.
● Design Strategy: Often used in dual-layer beds (alumina + molecular sieve) or mixed beds to optimize adsorption kinetics and lifespan.
With over 30 years of experience, JOOZEO offers advanced activated alumina and molecular sieve solutions. By optimizing purification processes (e.g., adsorbent ratios and regeneration strategies), we help customers significantly improve air separation unit efficiency and reliability.
Post time: Jun-23-2025