What is Carbon Molecular Sieve?

What is Carbon Molecular Sieve (CMS)?

Carbon Molecular Sieve (CMS), also known as CMS, is a microporous carbon adsorbent used to separate gases by molecular size and adsorption rate. In PSA Nitrogen Generation, CMS fills the vessels and selectively adsorbs oxygen from compressed air while nitrogen passes through as the product gas. As a result, PSA nitrogen systems commonly use two vessels that alternate between adsorption and regeneration to provide a continuous nitrogen supply.

CMS differs from standard activated carbon because its pore entrances are engineered to enable very selective gas separation. Therefore, CMS is widely used in onsite nitrogen generation systems where purity, repeatability, and compact system design are important.

Moreover, Carbon molecular sieves are available in different grades and pellet sizes to match nitrogen purity targets, flow rates, vessel dimensions, and operating conditions. Choosing the right CMS grade depends on the generator design and the required nitrogen specification.

How Does CMS Work in a Nitrogen Generator?

A PSA nitrogen generator uses compressed air as the feed gas. The air first passes through pretreatment, minimizing oil, water, and contaminants before entering the CMS bed. The clean compressed air then enters a vessel filled with carbon molecular sieve. CMS adsorbs oxygen under pressure and allows nitrogen to pass through as the product gas. When the bed nears saturation, the vessel depressurizes, releases the trapped gases, and prepares the CMS for the next cycle. A second vessel continues production while the first regenerates.

1. Adsorption: Compressed air enters a CMS packed vessel in a nitrogen generator.
2. Molecular sieving: Tiny pores in the carbon selectively capture oxygen and other small impurities.
3. Nitrogen output: Clean, high purity nitrogen exits the vessel.
4. Regeneration: The system depressurizes the CMS bed to release captured gases and prepare it for the next cycle.

Why CMS Used for PSA Nitrogen Generation?

SorbiTech™ Carbon molecular sieves used in PSA nitrogen generators because they enable efficient onsite nitrogen production without cryogenic separation. PSA systems using CMS widely used in industries that require a continuous nitrogen supply generated directly from compressed air.

Key Features of Carbon Molecular Sieves

The performance of CMS depends on its pore structure, adsorption characteristics, pellet strength, and resistance to contamination. Sources consistently describe CMS as a carbon material with micropores engineered for oxygen and nitrogen separation in PSA duty.

• Engineered micropore structure for oxygen and nitrogen separation
• Suitable pellet strength for PSA cycling
• Stable performance under proper inlet air treatment
• Available in multiple grades for different purity and flow requirements
• Designed for repeated adsorption and regeneration cycles

Carbon Molecular Sieve Applications

CMS most closely associated with PSA nitrogen generation, but the end uses of that nitrogen cover many industries. Industry sources report the use of nitrogen generators in metal processing, food packaging, electronics, pharmaceuticals, and other manufacturing environments.

Common industrial uses of nitrogen generated with CMS

• Food packaging
• Laser cutting
• Heat treatment
• Electronics manufacturing
• Pharmaceutical processing
• Chemical plants
• Tire inflation
• Inerting and blanketing
• Specialty industrial gas applications

How to Select the Right CMS Grade

Selecting the right carbon molecular sieve depends on your target nitrogen purity, vessel design, flow rate, cycle speed, and pellet size. SorbiTech™ offers different CMS grades to meet different PSA nitrogen generator requirements. Contact us today with your system details to get the best Carbon Molecular Sieve Grade for your application.