Experimental evidence and mechanism of the oxygen storage capacity in MnO2-Ce(1−x)ZrxO2/TiO2 catalyst for low-temperature SCR

The oxygen storage capacity of amorphous CeO 2 and its mechanism were investigated in a Zr-doped MnO x -CeO 2 /TiO 2 catalyst at low temperatures. The oxygen storage capacity of several catalysts was determined by the release of lattice oxygen upon reduction of Ce 4+ to Ce 3+ . We designed a temperature programmed reduction analysis using ammonia gas to measure the amount of lattice oxygen release and identify a decrease in reaction-onset temperature from 136 °C to 75 °C upon doping the catalyst with Zr. Additional reduction was observed in Zr-doped MnO x -CeO 2 /TiO 2 and this was attributed to an increase in temperature sensitivity of thermal vibrations of the first Ce–O coordination shell. The temperature dependence of the thermal vibrations was identified by examining the behavior of the Debye–Waller factor as a function of temperature with fitting the extended X-ray absorption fine structure.