Catalytic decomposition of nitrous oxide over calcined cobalt aluminum hydrotalcites

Catalytic decomposition of nitrous oxide has been carried out over calcined cobalt aluminum hydrotalcites of general formula [Co1-xAlx (OH)(2)[CO3](x/ 2) H2O where x = 0.25-0.33 at 50 Torr (1 Torr = 133 Pa) initial pressure of N2O in a static glass recirculatory reactor (130 cc) in the temperature ra nge 150-280 degrees C. All catalysts showed a first order dependence in N2O without significant oxygen inhibition. The activity increased with an incr ease in cobalt concentration present in the sample. The catalyst precursor synthesized under low supersaturation (LS) exhibited a higher activity than the precursor synthesized by sequential precipitation (SP) method. The obs erved trend in the activity is explained based on the surface concentration of cobalt, determined by XPS and matrix effects. Prior to catalytic studie s, the fresh and calcined samples were characterized by various physicochem ical techniques such as XRD, FT-IR, TG-DSC, TEM (with EDAX) and BET surface area measurements. (C) 1999 Elsevier Science B.V. All rights reserved.