NITROGEN MONOXIDE ADSORPTION AND CONTACT DECOMPOSITION PROPERTIES OF CO(II) COMPLEXES

We have carried out the feasibility study on the contact decomposition of NO by metal complexes such as metallotetraphenylporphyrins (MTPPs : M = Co (II), Cr (III), Zn (II), Ag (II:), Ru (II)) and Co (salen). F irstly, the NO adsorption properties of these metal complexes were eva luated by UV-vis and FT-IR spectroscopy. Among these complexes, both C oTPP and Co(salen) showed excellent NO adsorption ability. Two kinds o f NO- species adsorbed on the center metal ion were observed for both CoTPP and Co (salen), and a new peak (1528 cm(-1)) which was assigned to a bridging NO between two adjacent NO- molecules appeared gradually for Co(salen) by the exposure to NO at around 1000 ppm. In the case o f CoTPP, the bridging NO was observed by the exposure to NO of higher than 1 %. Secondly, the contact decomposition properties of NO were in vestigated using CoTPP and Co (salen). These complexes were impregnate d with porous glasses and employed as catalysts. Main decomposition sp ecies were N2O and N-2. The performance of the NO decomposition by Co( salen) was better than that of CoTPP. The maximum efficiency of NO dec omposition at 190 degrees C by Co(salen) was 84% for inlet gas (NO : 3 00 ppm, O-2 : 0.9%, in He). These results indicate that the NO contact decomposition is possible under O-2 coexistence condition without any reduction reagent.