Selective catalytic reduction of NOx by H2 using proton conductors as catalyst supports

The selective catalytic reduction (SCR) of NOx by H2 was studied using proton-conducting Sn0.9In0.1P2O7 as a catalyst support at 50–350 °C. When a mixture of 800 ppm NO, 1400–8400 ppm H2, and 5% O2 in Ar was introduced to the Pt/C working electrode, NOx was reduced to N2 with N2 selectivity values >80%>80%. The reaction mechanism was shown to be based on a mixed potential at the Pt/C working electrode. This mechanism was also applicable to a Sn0.9In0.1P2O7-supported Pt catalyst. H2 SCR over the Pt/Sn0.9In0.1P2O7 catalyst was characterized by a wide operating temperature window (50–350 °C) and remarkable N2 selectivity values (>80%>80%). Catalyst performance could be further improved by the addition of Rh to Pt, in which NOx conversion was a maximum 1.4 times higher than that over the Pt/Sn0.9In0.1P2O7 catalyst and N2 selectivity was increased to >89%>89% at all temperatures tested.