About gas-phase adsorbents

Sulfur gas adsorption function of silver zeolite

Silver zeolite exhibits highly efficient, selective, and durable removal performance for sulfur gases such as hydrogen sulfide (H₂S) and methyl mercaptan (CH₃SH). This is achieved through chemical adsorption, where silver ions strongly react with sulfur atoms.

Test example

In a removal test where an air stream (200 cc/min) containing 22 ppm of TBM (tert-butyl mercaptan), a typical odorant used in city gas, was passed through a silver zeolite column (0.7 g), the silver zeolite exhibited high removal efficiency by almost completely adsorbing the TBM during the initial stage.

Expected Applications

• Removal of odorants (TBM) in city gas
• Removal of sulfur-containing impurities in biogas
• Removal of sulfur-containing impurities in solvents

Adsorbable Sulfur Gases

• Hydrogen sulfide (H₂S)
• Mercaptans (CH₃SH, TBM)
• Sulfides (DMS, DMSD)

Hydrogen Adsorption Function of Silver Zeolite

High-vacuum insulated containers need to maintain a high level of vacuum inside the container for extended periods to ensure excellent thermal insulation performance. However, materials used for the container, such as carbon steel and stainless steel, gradually release outgassing (especially hydrogen gas), causing a decrease in vacuum level. Silver zeolite efficiently adsorbs and removes trace amounts of hydrogen gas generated under high vacuum conditions, contributing to the long-term stabilization of the vacuum environment.

Test Example

As a pretreatment, the silver zeolite was vacuum degassed at 350°C for 6 hours and then cooled to room temperature (25°C). Subsequently, the hydrogen (H₂) gas adsorption isotherm was measured using a BET apparatus.
As a result, a high hydrogen gas adsorption capacity of approximately 10 cc/g was confirmed under low pressure conditions at 20 Pa.

Expected Application

• Hydrogen getter material (for ultra-high vacuum insulated containers)

Radon Adsorption Function of Silver Zeolite (AgFER)

In underground particle physics experiments, radon-a radioactive noble gas-is a major source of background radiation, making its removal essential.
Conventional removal systems using activated carbon are large and costly in terms of installation space, creating a demand for more compact systems.
Silver zeolite adsorbs radon at a higher capacity than activated carbon, raising expectations for downsizing the equipment.

* Related literature: Study of Radon Removal Performance of SilverIon Exchanged Zeolite from Air for Underground Experiments

Test Example

Using pure air as the carrier gas, humidity was controlled with a cryogenic system at -70°C to -90°C. Radon from a radon source was passed through a U-shaped column filled with silver zeolite, and the radon concentration in the air was measured using a radon detector.
(Conducted by Kobe University)
The results confirmed that silver zeolite has approximately 1,000 times higher adsorption capacity compared to conventional activated carbon used as a radon adsorbent.

[2] Kobe u, Takagi_Mthesis(2024)

Expected Applications

• Neutrino observation facility (Kamiokande)

Nitrogen Adsorption Function of Copper Zeolite (CuZSM5)

It is required to efficiently adsorb and remove nitrogen gas, which hinders the performance maintenance of vacuum insulation materials, thereby preserving the insulation performance over the long term. Copper-supported zeolite (CuZSM5) exhibits high nitrogen adsorption performance even at room temperature and low pressure.

Test Example

As a pretreatment, the sample* was subjected to vacuum degassing at 500°C for 3 hours, then cooled to room temperature (25°C). Using a BET apparatus, the nitrogen adsorption isotherm was measured, and the amount of nitrogen gas adsorbed at a pressure of 10 Pa was determined.
The results showed that nitrogen adsorption increased with copper loading, and furthermore, by changing the copper loading method (Method C), the adsorption amount was dramatically enhanced.

• * Sample (adsorbent): Copper-loaded ZSM-5
• * Three types with different copper loading methods

Expected Applications

• Vacuum Insulation Panels (VIP) (refrigerators, freezers)
• Liquid fuel storage tanks

Iodine Adsorption Function of Silver Zeolite

Silver zeolite exhibits high adsorption performance for iodine ions, including radioactive iodine. Chemical adsorption is promoted through the strong binding between silver ions and iodine ions, enabling highly efficient and stable removal.

Test Example

A batch test was conducted by stirring an aqueous solution containing 100 ppm of iodine ions (30 ml) with silver zeolite (0.1 g) at 25°C for 2 hours at 200 rpm. As a result, the silver zeolite exhibited high adsorption performance.

Expected Application

• Treatment of radioactive iodine-contaminated water

Heavy Metal Ion Adsorption Function of Zeolite

Japan's tap water is among the highest quality in the world. However, in many regions across the globe, water pollution caused by harmful substances such as heavy metal ions and PFAS (per- and polyfluoroalkyl substances) remains a serious issue.
Zeolite has the ability to adsorb and remove cations, making it a promising material for purifying drinking water contaminated with heavy metal ions.

Test Example

A 500 mL solution containing metal ions at the concentrations shown in the table was treated with 50 mg of the heavy metal adsorption zeolite “LH210N.” The solution was stirred at 25°C for 24 hours, and the removal rate was calculated by comparing the residual metal ion concentrations with the initial concentrations.
As a result, LH210N demonstrated excellent removal performance for lead (Pb), copper (Cu), zinc (Zn), and cadmium (Cd).

Expected Application

• Water treatment filters