Catalytic reduction of NO by methane using a Pt/C/polybenzimidazole/Pt/C fuel cell

The catalytic NO reduction by methane was studied using a (NO,CH₄,Ar),Pt|polybenzimidazole(PBI)–H₃PO₄|Pt,(H₂,Ar) fuel cell at 135 and 165°C. It has been found that, without any reducing agent (like CH₄), NO can be electrochemically reduced in the (NO, Ar), Pt/C|PBI–H₃PO₄|Pt/C, (H₂,Ar) fuel cell with participation of H⁺ or electrochemically produced hydrogen. When added, methane partially suppresses the electrochemical reduction of NO. Methane outlet concentration monitoring has shown the CH₄ participation in the chemical catalytic reduction, i.e., methane co-adsorption with NO inhibited the electrochemical NO reduction and introduced a dominant chemical path of the NO reduction. The products of the NO reduction with methane were N₂, C₂H₄, and water. The catalytic NO reduction by methane was promoted when the catalyst was negatively polarized (−0.2 V). Repeated negative polarization of the catalyst increased the NO conversion. Maximum NO conversion was 48%. This effect was explained as a result of the reaction of the electrochemically produced hydrogen.