DRIFTS-MS Investigation of Low-Temperature CO Oxidation on Cu-Doped Manganese Oxide Prepared Using Nitrate Aerosol Decomposition
Cu-doped manganese oxide (Cu–Mn2O4) prepared using aerosol decomposition was used as a CO oxidation catalyst. Cu was successfully doped into Mn2O4due to their nitrate precursors having closed thermal decomposition properties, which ensured the atomic ratio of Cu/(Cu + Mn) in Cu–Mn2O4close to that in their nitrate precursors. The 0.5Cu–Mn2O4catalyst of 0.48 Cu/(Cu + Mn) atomic ratio had the best CO oxidation performance, withT50andT90as low as 48 and 69 °C, respectively. The 0.5Cu–Mn2O4catalyst also had (1) a hollow sphere morphology, where the sphere wall was composed of a large number of nanospheres (about 10 nm), (2) the largest specific surface area and defects on the interfacing of the nanospheres, and (3) the highest Mn3+, Cu+, and Oads ratios, which facilitated oxygen vacancy formation, CO adsorption, and CO oxidation, respectively, yielding a synergetic effect on CO oxidation. DRIFTS-MS analysis results showed that terminal-type oxygen (M=O) and bridge-type oxygen (M-O-M) on 0.5Cu–Mn2O4were reactive at a low temperature, resulting in-good low-temperature CO oxidation performance. Water could adsorb on 0.5Cu–Mn2O4and inhibited M=O and M-O-M reaction with CO. Water could not inhibit O2decomposition to M=O and M-O-M. The 0.5Cu–Mn2O4catalyst had excellent water resistance at 150 °C, at which the influence of water (up to 5%) on CO oxidation could be completely eliminated.Keywords:doping;Cu–Mn2O4;CO oxidation;oxygen vacancy;water resistance;DRIFTS-MS
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