Effect of potassium in calcined Co-Mn-Al layered double hydroxide on the catalytic decomposition of N2O

A series of catalysts was prepared by thermal treatment (500 degrees C) of the coprecipitated Co-Mn-Al layered double hydroxide (Co:Mn:Al molar ratio of 4:1:1) doped with various amount of potassium (0-3 wt%). Obtained spinel-like mixed oxides were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, BET surface area measurements, temperature-programmed H-2 reduction, and temperature-programmed CO2 and NH3 desorption. The prepared catalysts were tested for N2O decomposition to determine the effect of K addition on the catalytic activity in the presence of O-2, NOx and H2O. An optimum K content of ca. 0.9-1.6 wt% was found to achieve a high catalytic activity in the presence of O-2 and H2O, while the non-modified Co-Mn-Al mixed oxide was the most active catalyst in the presence of O-2 and NOx. The addition of potassium to the Co-Mn-Al mixed oxide apparently results in a modification of both electronic properties of active metals and acid-base function of the catalyst surface. (C) 2009 Elsevier B.V. All rights reserved.