Selective catalytic reduction of N2O with CH4 on Ni-MOR: A comparison with Co-MOR and Fe-MOR catalysts

•Ni-MOR, Co-MOR and Fe-MOR are active for SCR of N2O with CH4 in the presence of O2.•Despite relative H+ and Na+ amount, the activity order is Fe-MOR > Ni-MOR > Co-MOR.•The CO2 selectivity is 100% on Ni-MOR and lower on Fe-MOR and Co-MOR.•Ni-MOR are promising catalysts for the simultaneous SCR of N2O and NOx using CH4.•On all catalysts FTIR showed isolated tmi with at least two coordinative vacancies.

The selective catalytic reduction of N2O with CH4 in the presence of excess O2 (CH4-SCRN2OCH4-SCRN2O) and CH4 + O2 reaction were studied on Ni-MOR, Co-MOR and Fe-MOR, prepared from H-MOR or Na-MOR, by ion-exchange or CVD.FTIR showed that transition metal ions (tmi) were well dispersed, mainly isolated with at least two coordinative vacancies. For CH4-SCRN2OCH4-SCRN2O, irrespective of Brønsted acid site and Na+ amount, catalysts were active in the order Fe-MOR > Ni-MOR > Co-MOR. Using a methane-poor mixture, on all samples CH4-SCRN2OCH4-SCRN2O consisted of two nearly independent reactions: CH4 + N2O and CH4 + O2. Using a methane-rich mixture, CH4-SCRN2OCH4-SCRN2O consisted of a CH4 + N2O + O2 reaction, whose stoichiometric ratios depended on the tmi. Whereas on Ni-MOR methane combustion occurred as side reaction, on Co-MOR and Fe-MOR no side reactions occurred. Accordingly, for CH4 + O2 Co-MOR and Fe-MOR were poorly active, whereas Ni-MOR were highly active.We conclude that in CH4-SCRN2OCH4-SCRN2O a monoatomic oxygen form activates methane on Co-MOR and Fe-MOR catalysts, whereas both a monoatomic oxygen form and a molecular oxygen form activate methane on Ni-MOR. Being active for the CH4-SCRN2OCH4-SCRN2O and CH4-SCRNOxCH4-SCRNOx and forming CO only in traces, Ni-MOR are promising catalysts for the simultaneous SCR of N2O and NOx using CH4 as reducing agent.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (255 K)Download as PowerPoint slide