Dry citrate-precursor synthesized nanocrystalline cobalt oxide as highly active catalyst for total oxidation of propane

A set of nanocrystalline cobalt oxide (Co3O4)-based catalysts have been prepared by means of an innovative soft reactive grinding (SRG) procedure. The catalysts exhibited excellent activities and high stabilities for propane catalytic combustion. Complete conversion has been achieved at reaction temperatures as low as 240 degrees C. Comparing with the highly active Co3O4 catalysts in the current literature, the catalysts in this work show exceptionally high specific rate for propane total oxidation (ca. 91.3 mmolc(3) m(-2) h(-1) at 200 degrees C). A correlation between the O-2-TPD results and the activity for Co3O4 reveals that a high concentration of superficial electrophilic oxygen (O-) species is important for achieving a high activity. The prominent lattice distortion induced by prolonged citrate-precursor grinding is suggested to play a key role in creating and maintaining a high density of surface defects, which leads to highly activity and stability of the cobalt spinel catalyst. (C) 2009 Elsevier Inc. All rights reserved.