Catalytic decomposition of nitrous oxide N_2O: a study for p-block-element lead in PbO-ZrO_2/Al_2O_3 systems

摘要

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.