MECHANISTIC STUDY OF THE HETEROGENEOUS CONVERSION OF NO2 INTO HONO AND N2O ON ACID SURFACES

The heterogeneous conversion of NO2 into HONO and N2O on acid surfaces has been investigated in an 11 1 Pyrex glass reactor under simulated atmospheric conditions and in a 64 1 quartz glass reactor at reduced p ressure. NO2, N2O and HONO were monitored with time by long-path tunab le IR diode laser absorption spectroscopy using single vibrational rot ational lines at 1641.0, 1254.47 and 1254.46 cm(-1), respectively. The experimental results show that NO, is heterogeneously converted on ac id surfaces into HONO and then into N2O. HONO formation in the reactio n system has been found to occur by the heterogeneous reaction of NO2 with adsorbed water on the surface and does not require NO. The experi mental findings indicate that the nitrosyl ion probably plays an impor tant role in converting HONO into N2O and HNO3. A mechanism is propose d which can explain the experimental findings.