Catalytic decomposition of nitrous oxide N 2O: a study for p-block-element lead in PbO—ZrO2/Al2O3 systems

PbO—ZrO₂ catalysts have been prepared by sequential impregnation/calcination onto Al₂O₃ support for high concentration N₂O (27.97 mol%) decomposition. The p-block-element involved material system has been investigated with GC, BET, DTA, XRD and catalytic activity evaluation. It is found that with an atomic ratio Pb:Zr = 1:6 the material system shows the best catalytic performance for the decomposition. The catalyst with this composition has a tetragonal phase of ZrO₂ over reaction temperatures. The catalytic activity observed can be attributed to the presence of Pb cations with mixed valence states in tetragonal ZrO₂ lattice. Doping gases such as H₂O, CO₂, and O₂ are also mixed into the N₂O and studied. It is found that N₂O adsorption is rate-limiting step for the decomposition reaction. The reaction can be described as first order with respect to partial pressure of N₂O, considering that decomposition product O₂ exhibits no inhibition effect on the reaction in high conversion region.