A series of cobalt-magnesium oxide solid solution catalysts (CoMgO) have be
en prepared using urea combustion methods, and characterised by X-ray diffr
action (XRD) and laser Raman (LR). The catalytic activities for methane com
bustion have been tested in a continuous-flow microreactor. The Co content
has a significant effect on the activity of the cobalt-magnesium oxide soli
d solution catalysts. The catalysts containing 5 and 10% Co have the lowest
light-off temperature in methane combustion. In the preparation of cobalt-
magnesium oxide solid solution catalysts, higher urea to metal ratio favors
the formation of the catalysts with smaller crystal particles and leads to
a better catalytic performance for methane combustion. Addition of lanthan
um nitrate to the solution of Co and Mg nitrate depressed the formation of
the cobalt-magnesium oxide solid solution and decreased the activity of the
catalysts for methane combustion. The cobalt-magnesium oxide solid solutio
n catalysts are very stable when the calcination or reaction temperature is
no more than 900 degreesC. However, the catalytic activity decreases rapid
ly after high temperature (> 1000 degreesC) calcination, possibly due to si
ntering of the catalyst and thus decrease of the surface area.