Differences between 3A, 4A, and 5A Molecular Sieves

一、Differences in Pore Size

Pore size varies among molecular sieves, leading to differences in their filtration and separation capabilities. Simply put:

3A molecular sieves can only adsorb molecules smaller than 0.3 nanometers (nm);

4A molecular sieves require adsorbed molecules to be less than 0.4 nm;

The same principle applies to 5A molecular sieves (adsorbing molecules < 0.5 nm).

When used as a desiccant, a molecular sieve can adsorb at least 21% of its own weight in moisture.

二、Differences in Applications

3A Molecular Sieves are mainly used for drying petroleum cracking gas, olefins, refinery gas, and oilfield gas. They also serve as desiccants in industries such as chemicals, pharmaceuticals, and insulated glass. Typical applications include: drying liquids (e.g., ethanol), air drying in insulated glass, and refrigerant drying.

4A Molecular Sieves are primarily used for deep drying of gases and liquids such as air, natural gas, alkanes, and refrigerants; production and purification of argon; static drying of pharmaceutical packaging, electronic components, and perishable substances; and as dehydrating agents in paints, fuels, and coatings.

5A Molecular Sieves are mainly used for separating normal and isoparaffins; deep drying and purification of gases and liquids; separation of oxygen and nitrogen; and desulfurization of petroleum and liquefied petroleum gas (LPG). They can also act as adsorbents in dewaxing processes using steam as the desorbent.

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