Study of NO adsorption on activated carbons

Activated carbons (ACs) with varied porous textures and surface chemistry were studied for NO removal under different test conditions at temperatures below 100 °C. When oxygen is absent, there is almost no NO removal. When oxygen is present ACs act both as a catalyst for NO oxidation and as an adsorbent for NO adsorption. NO conversion is correlated with the presence of narrow micropores and is independent of surface area. ACs with an average micropore size around 7 Å exhibit the best NO removal capacity. NO rather than NO2 was observed to be the main adsorbed species during the initial period of adsorption. NO2 adsorption and NO2 gas release start only after the carbon surface was rapidly oxidized during the early stage of adsorption. The decomposition of NO2 formed through NO oxidation was believed to be responsible for the rapid carbon surface oxidation and NO chemisorption.