Carbon molecular sieves (CMS) are part of the microporous material category known for their high adsorption capacity and selectivity towards various gases. They have an amorphous structure with a well-developed surface area and pore sizes similar to small molecule diameters. For instance, molecular sieves used to separate nitrogen from air have pore sizes ranging from 0.3 to 0.5 nm, distinguishing them from conventional carbonaceous adsorbents with broader pore size distributions.

The unique properties of molecular sieves make them valuable as adsorbents for gas mixture separation, particularly in air separation applications. Carbon-based molecular sieves have been instrumental in the commercialization of pressure swing adsorption (PSA) processes for nitrogen-air separation.

Their hydrophobic surface and resistance to acidic and basic environments enhance their suitability for gas separation. They have demonstrated effectiveness in separating gas mixtures with molecules differing in critical sizes by as little as 0.02 nm. The ability to tailor molecular sieve properties during preparation adds to their appeal as industrial adsorbents.

Characteristics Carbon Molecular Sieve 4A
Chemical formula Na2O • Al2O3 • 2SiO2 • 9/2H2O

Silica-Alumina ratio:        SiO2/ Al2O3 ≈ 2

CAS Number 70955-01-0
Other names zeolite
Molecular Weight 1704.65 gm
Appearance Cylindrical black solid, countless, extremely fine pore
Density 650-800 kg/m3



Carbon Molecular Sieve has emerged as a highly dependable drying agent used in a range of applications such as:

  • Dehumidifying refrigerants
  • Removing moisture from PU plastic or paint
  • Drying natural gas
  • Treating cracked gas
  • Drying glass units, whether filled with air or gas
  • Dehydrating highly polar compounds like methanol and ethanol
  • Removing moisture from unsaturated hydrocarbons such as ethylene, propylene, and butadiene

Environmental impact and sustainability of Carbon Molecular Sieve

Molecular sieves have a relatively low environmental impact compared to other adsorbent materials. This is due to several factors:

High Efficiency: Molecular sieves demonstrate excellent adsorption performance, allowing for more efficient separation and purification processes.

Regenerability: Molecular sieves can be regenerated and reused multiple times, reducing the need for frequent replacement and disposal.

Potential for Recycling and Reuse: After their useful life, molecular sieves can often be recycled or reused, further minimizing their environmental footprint.


This chemical is supplied in different-sized plastic drums