The hopcalite catalyst in carbon monoxide poisoning prevention masks

1. Why is a special CO gas mask needed?

Common toxic gases (such as chlorine and ammonia) can be filtered using adsorbents like activated carbon, but carbon monoxide has relatively unique properties . Its molecules are very stable and have low polarity, making physical adsorption ineffective and difficult for activated carbon to adsorb. Furthermore, carbon monoxide is a highly toxic gas to humans; its binding affinity to hemoglobin is 200-300 times that of oxygen, and even low concentrations can negatively impact human health .

2. Why the hopcalite catalyst?

01. As mentioned above, carbon monoxide is difficult to be physically adsorbed, so chemical conversion methods must be used to eliminate it . The reaction principle is catalytic oxidation .

02. This reaction usually occurs at room temperature, so a catalyst that can accelerate the catalytic oxidation of carbon monoxide at room temperature is needed, and the best choice on the market is the hopcalite catalyst.

03. Hopcalite catalyst is essentially a copper-manganese composite component, a transition metal oxide catalyst formulated in a certain proportion .

Its key feature is that it can efficiently catalytically oxidize CO into non-toxic CO₂ at room temperature (even below 0°C) , making it extremely cost-effective compared to precious metal catalysts such as platinum and palladium .

3. Principle and design of gas masks

01. Working principle of the hopcalite catalyst

The hopcalite catalyst in gas masks is typically in small granular form packed inside the filter canister . When CO-containing air flows through it ,

CO and O₂ diffuse to the catalyst surface . They are activated and transformed at the active sites of the hopcalite catalyst . CO reacts with O₂ on the surface to form CO₂ , which then desorbs from the catalyst surface and is expelled with exhaled gas. The entire process is completed instantaneously at room temperature, providing users with safe breathing gas.

02. Filter canister configuration design 

Pre-filter layer:

Typically located before the hopcalite layer, it serves two purposes: firstly , dehumidification , adsorbing water vapor from the air to prevent moisture from deactivating the catalyst; and secondly, dust removal , removing particulate matter to prevent clogging of the catalyst bed.

Catalyst layer:

It is the core component of the filter canister, namely the hopcalite catalyst , which is specifically designed for CO.

Post-adsorption layer:

It may contain activated carbon to remove other potentially present organic vapor toxins, thus providing comprehensive protection .

4. Gas masks are not a panacea

Limitations of use:

May be less effective in environments with very low oxygen levels .

Precautions for use:

01. "Water-sensitive," hopcalite catalyst rapidly deactivates upon contact with water or high humidity . Moisture reacts irreversibly with the active sites, leading to catalyst poisoning. Therefore , the filter canister must be sealed tightly to prevent moisture absorption, and its expiration date must be carefully observed.