How Water Helps Ru/MoOx Catalysts Clean Up Toxic Air

Breathing in chlorinated and oxygenated volatile organic compounds (CVOCs and OVOCs) can be dangerous. One way to get rid of these pollutants is by using catalysts that oxidize them. The challenge is keeping these catalysts working well over time. A team of researchers looked into this issue using a catalyst made of Ru/MoOx/HZSM-5 (where M can be W or Mo) to break down chlorobenzene (CB) and ethyl acetate (EA). They found that by adding MoOx to the mix, the catalyst could handle more structural hydroxyl groups and keep a balance in surface acidity. This made it more stable and effective, especially for dealing with CB and EA.

When water vapor was added to the mix, it boosted the catalyst's ability to clean up the pollutants and protected its active sites from being damaged by chlorine. The combination of the Mo-O(H)-Al structure in Ru/MoOx/HZSM-5 and the Si-OH-Al structure helped water get activated, creating bridging hydroxyl groups. These groups offer a proton-rich environment that speeds up the process of breaking down the pollutants. The researchers also noticed that water reacted with adsorbed oxygen species to create highly active hydroxyl radicals (OOH). These radicals help in the deep oxidation of pollutant intermediates, making the whole process more efficient. The study suggests that this approach can be a clever way to deal with multiple types of air pollutants under tough conditions.

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