The Interaction between Silver and N20 in Relation to the Oxidative Dehydrogenation of Methanol

The interaction of N20 with pure silver at temperatures up to 900°C has been studied using temperature-programmed reduction and desorption; the interaction is compared with that of oxygen with silver. The effect of addition of NZO, as well as of the complete replacement of oxygen by NzO, on the oxidative dehydrogenation of methanol on a silver catalyst has also been studied. It was found that the interaction of silver with N20 was much slower than that of 02; no atomic surface oxygen species were observed, probably because the formation of subsurface species was not complete; selective adsorption appears to take place on the surface defects and grain boundaries involved in the formation of the subsurface species. Addition of small amounts of N,O to the reaction mixture (CHIOH + 03 for the oxidative dehydrogenation of methanol had almost no influence on the conversion or on the product distribution measured. However, the conversions were considerably lower when oxygen was totally replaced by NZO; only above 600°C was the N20 exhausted. At the same level of conversion of the methanol, the amount of CO2 produced was lowered compared to the case of Oz. This is in agreement with the suggestion that CO, is formed via weakly bound surface oxygen. %, 1988 Academic Press, Inc.