Mesoporous Cu-Mn Hopcalite catalyst and its performance in low temperature ethylene combustion in a carbon dioxide stream

Complete combustion of trace amounts of ethylene in food grade CO2 over a Cu-Mn Hopcalite catalyst has been investigated. A mesoporous structure is identified in the catalyst. Low temperature calcined samples are found to be more active than the high temperature calcined ones. The presence Of Cu2+ and Mn3+ is essential for the high activity of the catalyst. The Cu-Mn catalyst without a third component deactivates quickly in the reaction stream. However, doping with Al or Mg individually and with Ni-Al or Mg-Al simultaneously increases the lifetime. In situ DRIFTS measurements provide evidence that hydroxyl groups form and adsorb on Mn species. With the doping of Al, Mg and Ni ions, the amount of hydroxyl groups adsorbed reduces and the stability improves. Doping with Al and Mg simultaneously gives the best stability. A synergetic effect between CuO and amorphous Cu-Mn oxide phases is also confirmed. (C) 2009 Elsevier B.V. All rights reserved.