Study of the activity and selectivity of PtCZ and PtCZBa model catalysts in the reduction of NO by CO

Gas concentrations and selectivities concerning CO and NO consumptions for PtCZBa catalyst. Selet. NO=NOconsumed/(NOconsumed+COconsumed). Selet. CO=COconsumed/(NOconsumed+COconsumed). [Display omitted] •Model Pt–CZ mixed oxide catalysts for the reduction of NO by CO.•Selectivity to N2 above 450°C with significant N2O emissions at low temperatures.•Addition of barium oxide improved catalytic activity.•BaO increased the reducibility of the catalysts.•BaO inhibited the formation of Pt–O–Ce bonds, improving activity. The objective of this study was to evaluate model Pt catalysts supported on ceria–zirconia, with and without barium, for the reduction of NO by CO on stoichiometric conditions. The supports were named CZ and CZBa. The supports impregnated with Pt were named PtCZ and PtCZBa. The presence of Ba improved the reducibility of the catalysts, which probably contributed to ameliorate the catalytic activity. Lightoff curves showed two peaks of N2O: one at low temperature (250°C) and another at high temperature (425°C). The catalysts with Pt only reached significant activity and selectivity to N2 above 450°C. According to the literature, the reaction mechanism changes depending on the temperature. At low temperature, the mechanism of N2O production probably occurs by redox reactions with the metal promoting the creation of the oxygen vacancies over the CZ support by CO activation. Barium presence improve the activity and the N2 selectivity.