Interactions of NO2 and NO with carbonaceous adsorbents containing silver nanoparticles.

Interactions of NO(2) and NO (the product of NO(2) reduction by carbon) with biomass-based carbonaceous materials with silver nanoparticles deposited on the surface were studied. The surface of the materials was characterized using adsorption of nitrogen, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA). The results showed that the amount of NO(2) adsorbed, its conversion to NO, and the amount of NO released from the carbon surface depend on the carbon's content of silver. More silver results in a better performance of the adsorbent. The products of NO(2) interactions with silver include surface chelates such as Ag(2)-O-NO or Ag-O(2)-NO. Another element, active in the surface reactions with NO(2), is phosphorus. Both silver and phosphorus species are oxidized by NO(2). The product of NO(2) reduction, NO, is either retained on the carbon surface by its interactions with metallic silver or is further reduced to N(2)O or N(2). Besides silver, carbon support is also active in the reduction of NO(2) to NO. Carbon monoxide formed in such a processes can reduce silver oxide nanoparticles, and thus, it provides more metallic silver for interactions with NO.