The simultaneous selective catalytic reduction of N2O and NOXwith CH4 on Co- and Ni-exchanged mordenite

Co- or Ni-exchanged Na-MOR (Si/Al = 9.2) prepared by ion-exchange method were characterized by in situUV–vis DRS and FTIR. We studied the selective catalytic reduction with CH4in the presence of O2(CH4-SCR) for the simultaneous abatement of NO and N2O (CH4-SCRsim) and the related reactions: (i) abatementof N2O (CH4− SCRN2O), (ii) abatement of NO (CH4-SCRNO), (iii) N2O decomposition, and (iv) CH4combus-tion. The catalytic measurements were performed in a flow apparatus with GC analysis of reactants andproducts.FTIR characterization with CO of Ni-MOR identified isolated Ni2+and [Ni2+O Ni2+] dimers, bothmainly located in -sites. In Ni-MOR, the amount of isolated Ni2+and of dimers was comparable, whereasin Co-MOR isolated Co2+were more abundant than [Co2+O Co2+]. Transition metal ion (tmi) dimerswere easily reduced by CO to [tmi+ tmi+] yielding CO2. In situ UV–vis DRS characterization indicatedthat by heating in N2O, Co2+oxidized to Co3+O−, whereas Ni2+did not.Catalytic results for CH4-SCR